add lab answers

labcodes_answer/lab1_result/Makefile

@@ -0,0 +1,250 @@
+PROJ	:= challenge
+EMPTY	:=
+SPACE	:= $(EMPTY) $(EMPTY)
+SLASH	:= /
+
+V       := @
+
+# try to infer the correct GCCPREFX
+ifndef GCCPREFIX
+GCCPREFIX := $(shell if i386-elf-objdump -i 2>&1 | grep '^elf32-i386$$' >/dev/null 2>&1; \
+	then echo 'i386-elf-'; \
+	elif objdump -i 2>&1 | grep 'elf32-i386' >/dev/null 2>&1; \
+	then echo ''; \
+	else echo "***" 1>&2; \
+	echo "*** Error: Couldn't find an i386-elf version of GCC/binutils." 1>&2; \
+	echo "*** Is the directory with i386-elf-gcc in your PATH?" 1>&2; \
+	echo "*** If your i386-elf toolchain is installed with a command" 1>&2; \
+	echo "*** prefix other than 'i386-elf-', set your GCCPREFIX" 1>&2; \
+	echo "*** environment variable to that prefix and run 'make' again." 1>&2; \
+	echo "*** To turn off this error, run 'gmake GCCPREFIX= ...'." 1>&2; \
+	echo "***" 1>&2; exit 1; fi)
+endif
+
+# try to infer the correct QEMU
+ifndef QEMU
+QEMU := $(shell if which qemu > /dev/null; \
+	then echo 'qemu'; exit; \
+	elif which i386-elf-qemu > /dev/null; \
+	then echo 'i386-elf-qemu'; exit; \
+	else \
+	echo "***" 1>&2; \
+	echo "*** Error: Couldn't find a working QEMU executable." 1>&2; \
+	echo "*** Is the directory containing the qemu binary in your PATH" 1>&2; \
+	echo "***" 1>&2; exit 1; fi)
+endif
+
+# eliminate default suffix rules
+.SUFFIXES: .c .S .h
+
+# delete target files if there is an error (or make is interrupted)
+.DELETE_ON_ERROR:
+
+# define compiler and flags
+
+HOSTCC		:= gcc
+HOSTCFLAGS	:= -g -Wall -O2
+
+CC		:= $(GCCPREFIX)gcc
+CFLAGS	:= -fno-builtin -Wall -ggdb -m32 -gstabs -nostdinc $(DEFS)
+CFLAGS	+= $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector)
+CTYPE	:= c S
+
+LD      := $(GCCPREFIX)ld
+LDFLAGS	:= -m $(shell $(LD) -V | grep elf_i386 2>/dev/null)
+LDFLAGS	+= -nostdlib
+
+OBJCOPY := $(GCCPREFIX)objcopy
+OBJDUMP := $(GCCPREFIX)objdump
+
+COPY	:= cp
+MKDIR   := mkdir -p
+MV		:= mv
+RM		:= rm -f
+AWK		:= awk
+SED		:= sed
+SH		:= sh
+TR		:= tr
+TOUCH	:= touch -c
+
+OBJDIR	:= obj
+BINDIR	:= bin
+
+ALLOBJS	:=
+ALLDEPS	:=
+TARGETS	:=
+
+include tools/function.mk
+
+listf_cc = $(call listf,$(1),$(CTYPE))
+
+# for cc
+add_files_cc = $(call add_files,$(1),$(CC),$(CFLAGS) $(3),$(2),$(4))
+create_target_cc = $(call create_target,$(1),$(2),$(3),$(CC),$(CFLAGS))
+
+# for hostcc
+add_files_host = $(call add_files,$(1),$(HOSTCC),$(HOSTCFLAGS),$(2),$(3))
+create_target_host = $(call create_target,$(1),$(2),$(3),$(HOSTCC),$(HOSTCFLAGS))
+
+cgtype = $(patsubst %.$(2),%.$(3),$(1))
+objfile = $(call toobj,$(1))
+asmfile = $(call cgtype,$(call toobj,$(1)),o,asm)
+outfile = $(call cgtype,$(call toobj,$(1)),o,out)
+symfile = $(call cgtype,$(call toobj,$(1)),o,sym)
+
+# for match pattern
+match = $(shell echo $(2) | $(AWK) '{for(i=1;i<=NF;i++){if(match("$(1)","^"$$(i)"$$")){exit 1;}}}'; echo $$?)
+
+# >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
+# include kernel/user
+
+INCLUDE	+= libs/
+
+CFLAGS	+= $(addprefix -I,$(INCLUDE))
+
+LIBDIR	+= libs
+
+$(call add_files_cc,$(call listf_cc,$(LIBDIR)),libs,)
+
+# -------------------------------------------------------------------
+# kernel
+
+KINCLUDE	+= kern/debug/ \
+			   kern/driver/ \
+			   kern/trap/ \
+			   kern/mm/
+
+KSRCDIR		+= kern/init \
+			   kern/libs \
+			   kern/debug \
+			   kern/driver \
+			   kern/trap \
+			   kern/mm
+
+KCFLAGS		+= $(addprefix -I,$(KINCLUDE))
+
+$(call add_files_cc,$(call listf_cc,$(KSRCDIR)),kernel,$(KCFLAGS))
+
+KOBJS	= $(call read_packet,kernel libs)
+
+# create kernel target
+kernel = $(call totarget,kernel)
+
+$(kernel): tools/kernel.ld
+
+$(kernel): $(KOBJS)
+	@echo + ld $@
+	$(V)$(LD) $(LDFLAGS) -T tools/kernel.ld -o $@ $(KOBJS)
+	@$(OBJDUMP) -S $@ > $(call asmfile,kernel)
+	@$(OBJDUMP) -t $@ | $(SED) '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > $(call symfile,kernel)
+
+$(call create_target,kernel)
+
+# -------------------------------------------------------------------
+
+# create bootblock
+bootfiles = $(call listf_cc,boot)
+$(foreach f,$(bootfiles),$(call cc_compile,$(f),$(CC),$(CFLAGS) -Os -nostdinc))
+
+bootblock = $(call totarget,bootblock)
+
+$(bootblock): $(call toobj,$(bootfiles)) | $(call totarget,sign)
+	@echo + ld $@
+	$(V)$(LD) $(LDFLAGS) -N -e start -Ttext 0x7C00 $^ -o $(call toobj,bootblock)
+	@$(OBJDUMP) -S $(call objfile,bootblock) > $(call asmfile,bootblock)
+	@$(OBJCOPY) -S -O binary $(call objfile,bootblock) $(call outfile,bootblock)
+	@$(call totarget,sign) $(call outfile,bootblock) $(bootblock)
+
+$(call create_target,bootblock)
+
+# -------------------------------------------------------------------
+
+# create 'sign' tools
+$(call add_files_host,tools/sign.c,sign,sign)
+$(call create_target_host,sign,sign)
+
+# -------------------------------------------------------------------
+
+# create ucore.img
+UCOREIMG	:= $(call totarget,ucore.img)
+
+$(UCOREIMG): $(kernel) $(bootblock)
+	$(V)dd if=/dev/zero of=$@ count=10000
+	$(V)dd if=$(bootblock) of=$@ conv=notrunc
+	$(V)dd if=$(kernel) of=$@ seek=1 conv=notrunc
+
+$(call create_target,ucore.img)
+
+# >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
+
+$(call finish_all)
+
+IGNORE_ALLDEPS	= clean \
+				  dist-clean \
+				  grade \
+				  touch \
+				  print-.+ \
+				  handin
+
+ifeq ($(call match,$(MAKECMDGOALS),$(IGNORE_ALLDEPS)),0)
+-include $(ALLDEPS)
+endif
+
+# files for grade script
+
+TARGETS: $(TARGETS)
+
+.DEFAULT_GOAL := TARGETS
+
+.PHONY: qemu qemu-nox debug debug-nox
+qemu: $(UCOREIMG)
+	$(V)$(QEMU) -parallel stdio -hda $< -serial null
+
+qemu-nox: $(UCOREIMG)
+	$(V)$(QEMU) -serial mon:stdio -hda $< -nographic
+TERMINAL        :=gnome-terminal
+debug: $(UCOREIMG)
+	$(V)$(QEMU) -S -s -parallel stdio -hda $< -serial null &
+	$(V)sleep 2
+	$(V)$(TERMINAL) -e "gdb -q -x tools/gdbinit"
+	
+debug-nox: $(UCOREIMG)
+	$(V)$(QEMU) -S -s -serial mon:stdio -hda $< -nographic &
+	$(V)sleep 2
+	$(V)$(TERMINAL) -e "gdb -q -x tools/gdbinit"
+
+.PHONY: grade touch
+
+GRADE_GDB_IN	:= .gdb.in
+GRADE_QEMU_OUT	:= .qemu.out
+HANDIN			:= proj$(PROJ)-handin.tar.gz
+
+TOUCH_FILES		:= kern/trap/trap.c
+
+MAKEOPTS		:= --quiet --no-print-directory
+
+grade:
+	$(V)$(MAKE) $(MAKEOPTS) clean
+	$(V)$(SH) tools/grade.sh
+
+touch:
+	$(V)$(foreach f,$(TOUCH_FILES),$(TOUCH) $(f))
+
+print-%:
+	@echo $($(shell echo $(patsubst print-%,%,$@) | $(TR) [a-z] [A-Z]))
+
+.PHONY: clean dist-clean handin packall
+clean:
+	$(V)$(RM) $(GRADE_GDB_IN) $(GRADE_QEMU_OUT)
+	-$(RM) -r $(OBJDIR) $(BINDIR)
+
+dist-clean: clean
+	-$(RM) $(HANDIN)
+
+handin: packall
+	@echo Please visit http://learn.tsinghua.edu.cn and upload $(HANDIN). Thanks!
+
+packall: clean
+	@$(RM) -f $(HANDIN)
+	@tar -czf $(HANDIN) `find . -type f -o -type d | grep -v '^\.*$$' | grep -vF '$(HANDIN)'`
+

labcodes_answer/lab1_result/boot/asm.h

@@ -0,0 +1,26 @@
+#ifndef __BOOT_ASM_H__
+#define __BOOT_ASM_H__
+
+/* Assembler macros to create x86 segments */
+
+/* Normal segment */
+#define SEG_NULLASM                                             \
+    .word 0, 0;                                                 \
+    .byte 0, 0, 0, 0
+
+#define SEG_ASM(type,base,lim)                                  \
+    .word (((lim) >> 12) & 0xffff), ((base) & 0xffff);          \
+    .byte (((base) >> 16) & 0xff), (0x90 | (type)),             \
+        (0xC0 | (((lim) >> 28) & 0xf)), (((base) >> 24) & 0xff)
+
+
+/* Application segment type bits */
+#define STA_X       0x8     // Executable segment
+#define STA_E       0x4     // Expand down (non-executable segments)
+#define STA_C       0x4     // Conforming code segment (executable only)
+#define STA_W       0x2     // Writeable (non-executable segments)
+#define STA_R       0x2     // Readable (executable segments)
+#define STA_A       0x1     // Accessed
+
+#endif /* !__BOOT_ASM_H__ */
+

labcodes_answer/lab1_result/boot/bootasm.S

@@ -0,0 +1,86 @@
+#include <asm.h>
+
+# Start the CPU: switch to 32-bit protected mode, jump into C.
+# The BIOS loads this code from the first sector of the hard disk into
+# memory at physical address 0x7c00 and starts executing in real mode
+# with %cs=0 %ip=7c00.
+
+.set PROT_MODE_CSEG,        0x8                     # kernel code segment selector
+.set PROT_MODE_DSEG,        0x10                    # kernel data segment selector
+.set CR0_PE_ON,             0x1                     # protected mode enable flag
+
+# start address should be 0:7c00, in real mode, the beginning address of the running bootloader
+.globl start
+start:
+.code16                                             # Assemble for 16-bit mode
+    cli                                             # Disable interrupts
+    cld                                             # String operations increment
+
+    # Set up the important data segment registers (DS, ES, SS).
+    xorw %ax, %ax                                   # Segment number zero
+    movw %ax, %ds                                   # -> Data Segment
+    movw %ax, %es                                   # -> Extra Segment
+    movw %ax, %ss                                   # -> Stack Segment
+
+    # Enable A20:
+    #  For backwards compatibility with the earliest PCs, physical
+    #  address line 20 is tied low, so that addresses higher than
+    #  1MB wrap around to zero by default. This code undoes this.
+seta20.1:
+    inb $0x64, %al                                  # Wait for not busy
+    testb $0x2, %al
+    jnz seta20.1
+
+    movb $0xd1, %al                                 # 0xd1 -> port 0x64
+    outb %al, $0x64
+
+seta20.2:
+    inb $0x64, %al                                  # Wait for not busy
+    testb $0x2, %al
+    jnz seta20.2
+
+    movb $0xdf, %al                                 # 0xdf -> port 0x60
+    outb %al, $0x60
+
+    # Switch from real to protected mode, using a bootstrap GDT
+    # and segment translation that makes virtual addresses
+    # identical to physical addresses, so that the
+    # effective memory map does not change during the switch.
+    lgdt gdtdesc
+    movl %cr0, %eax
+    orl $CR0_PE_ON, %eax
+    movl %eax, %cr0
+
+    # Jump to next instruction, but in 32-bit code segment.
+    # Switches processor into 32-bit mode.
+    ljmp $PROT_MODE_CSEG, $protcseg
+
+.code32                                             # Assemble for 32-bit mode
+protcseg:
+    # Set up the protected-mode data segment registers
+    movw $PROT_MODE_DSEG, %ax                       # Our data segment selector
+    movw %ax, %ds                                   # -> DS: Data Segment
+    movw %ax, %es                                   # -> ES: Extra Segment
+    movw %ax, %fs                                   # -> FS
+    movw %ax, %gs                                   # -> GS
+    movw %ax, %ss                                   # -> SS: Stack Segment
+
+    # Set up the stack pointer and call into C. The stack region is from 0--start(0x7c00)
+    movl $0x0, %ebp
+    movl $start, %esp
+    call bootmain
+
+    # If bootmain returns (it shouldn't), loop.
+spin:
+    jmp spin
+
+# Bootstrap GDT
+.p2align 2                                          # force 4 byte alignment
+gdt:
+    SEG_NULLASM                                     # null seg
+    SEG_ASM(STA_X|STA_R, 0x0, 0xffffffff)           # code seg for bootloader and kernel
+    SEG_ASM(STA_W, 0x0, 0xffffffff)                 # data seg for bootloader and kernel
+
+gdtdesc:
+    .word 0x17                                      # sizeof(gdt) - 1
+    .long gdt                                       # address gdt

labcodes_answer/lab1_result/boot/bootmain.c

@@ -0,0 +1,116 @@
+#include <defs.h>
+#include <x86.h>
+#include <elf.h>
+
+/* *********************************************************************
+ * This a dirt simple boot loader, whose sole job is to boot
+ * an ELF kernel image from the first IDE hard disk.
+ *
+ * DISK LAYOUT
+ *  * This program(bootasm.S and bootmain.c) is the bootloader.
+ *    It should be stored in the first sector of the disk.
+ *
+ *  * The 2nd sector onward holds the kernel image.
+ *
+ *  * The kernel image must be in ELF format.
+ *
+ * BOOT UP STEPS
+ *  * when the CPU boots it loads the BIOS into memory and executes it
+ *
+ *  * the BIOS intializes devices, sets of the interrupt routines, and
+ *    reads the first sector of the boot device(e.g., hard-drive)
+ *    into memory and jumps to it.
+ *
+ *  * Assuming this boot loader is stored in the first sector of the
+ *    hard-drive, this code takes over...
+ *
+ *  * control starts in bootasm.S -- which sets up protected mode,
+ *    and a stack so C code then run, then calls bootmain()
+ *
+ *  * bootmain() in this file takes over, reads in the kernel and jumps to it.
+ * */
+
+#define SECTSIZE        512
+#define ELFHDR          ((struct elfhdr *)0x10000)      // scratch space
+
+/* waitdisk - wait for disk ready */
+static void
+waitdisk(void) {
+    while ((inb(0x1F7) & 0xC0) != 0x40)
+        /* do nothing */;
+}
+
+/* readsect - read a single sector at @secno into @dst */
+static void
+readsect(void *dst, uint32_t secno) {
+    // wait for disk to be ready
+    waitdisk();
+
+    outb(0x1F2, 1);                         // count = 1
+    outb(0x1F3, secno & 0xFF);
+    outb(0x1F4, (secno >> 8) & 0xFF);
+    outb(0x1F5, (secno >> 16) & 0xFF);
+    outb(0x1F6, ((secno >> 24) & 0xF) | 0xE0);
+    outb(0x1F7, 0x20);                      // cmd 0x20 - read sectors
+
+    // wait for disk to be ready
+    waitdisk();
+
+    // read a sector
+    insl(0x1F0, dst, SECTSIZE / 4);
+}
+
+/* *
+ * readseg - read @count bytes at @offset from kernel into virtual address @va,
+ * might copy more than asked.
+ * */
+static void
+readseg(uintptr_t va, uint32_t count, uint32_t offset) {
+    uintptr_t end_va = va + count;
+
+    // round down to sector boundary
+    va -= offset % SECTSIZE;
+
+    // translate from bytes to sectors; kernel starts at sector 1
+    uint32_t secno = (offset / SECTSIZE) + 1;
+
+    // If this is too slow, we could read lots of sectors at a time.
+    // We'd write more to memory than asked, but it doesn't matter --
+    // we load in increasing order.
+    for (; va < end_va; va += SECTSIZE, secno ++) {
+        readsect((void *)va, secno);
+    }
+}
+
+/* bootmain - the entry of bootloader */
+void
+bootmain(void) {
+    // read the 1st page off disk
+    readseg((uintptr_t)ELFHDR, SECTSIZE * 8, 0);
+
+    // is this a valid ELF?
+    if (ELFHDR->e_magic != ELF_MAGIC) {
+        goto bad;
+    }
+
+    struct proghdr *ph, *eph;
+
+    // load each program segment (ignores ph flags)
+    ph = (struct proghdr *)((uintptr_t)ELFHDR + ELFHDR->e_phoff);
+    eph = ph + ELFHDR->e_phnum;
+    for (; ph < eph; ph ++) {
+        readseg(ph->p_va & 0xFFFFFF, ph->p_memsz, ph->p_offset);
+    }
+
+    // call the entry point from the ELF header
+    // note: does not return
+    ((void (*)(void))(ELFHDR->e_entry & 0xFFFFFF))();
+
+bad:
+    outw(0x8A00, 0x8A00);
+    outw(0x8A00, 0x8E00);
+
+    /* do nothing */
+    while (1);
+}
+

labcodes_answer/lab1_result/kern/debug/assert.h

@@ -0,0 +1,27 @@
+#ifndef __KERN_DEBUG_ASSERT_H__
+#define __KERN_DEBUG_ASSERT_H__
+
+#include <defs.h>
+
+void __warn(const char *file, int line, const char *fmt, ...);
+void __noreturn __panic(const char *file, int line, const char *fmt, ...);
+
+#define warn(...)                                       \
+    __warn(__FILE__, __LINE__, __VA_ARGS__)
+
+#define panic(...)                                      \
+    __panic(__FILE__, __LINE__, __VA_ARGS__)
+
+#define assert(x)                                       \
+    do {                                                \
+        if (!(x)) {                                     \
+            panic("assertion failed: %s", #x);          \
+        }                                               \
+    } while (0)
+
+// static_assert(x) will generate a compile-time error if 'x' is false.
+#define static_assert(x)                                \
+    switch (x) { case 0: case (x): ; }
+
+#endif /* !__KERN_DEBUG_ASSERT_H__ */
+

labcodes_answer/lab1_result/kern/debug/kdebug.c

@@ -0,0 +1,320 @@
+#include <defs.h>
+#include <x86.h>
+#include <stab.h>
+#include <stdio.h>
+#include <string.h>
+#include <kdebug.h>
+
+#define STACKFRAME_DEPTH 20
+
+extern const struct stab __STAB_BEGIN__[];  // beginning of stabs table
+extern const struct stab __STAB_END__[];    // end of stabs table
+extern const char __STABSTR_BEGIN__[];      // beginning of string table
+extern const char __STABSTR_END__[];        // end of string table
+
+/* debug information about a particular instruction pointer */
+struct eipdebuginfo {
+    const char *eip_file;                   // source code filename for eip
+    int eip_line;                           // source code line number for eip
+    const char *eip_fn_name;                // name of function containing eip
+    int eip_fn_namelen;                     // length of function's name
+    uintptr_t eip_fn_addr;                  // start address of function
+    int eip_fn_narg;                        // number of function arguments
+};
+
+/* *
+ * stab_binsearch - according to the input, the initial value of
+ * range [*@region_left, *@region_right], find a single stab entry
+ * that includes the address @addr and matches the type @type,
+ * and then save its boundary to the locations that pointed
+ * by @region_left and @region_right.
+ *
+ * Some stab types are arranged in increasing order by instruction address.
+ * For example, N_FUN stabs (stab entries with n_type == N_FUN), which
+ * mark functions, and N_SO stabs, which mark source files.
+ *
+ * Given an instruction address, this function finds the single stab entry
+ * of type @type that contains that address.
+ *
+ * The search takes place within the range [*@region_left, *@region_right].
+ * Thus, to search an entire set of N stabs, you might do:
+ *
+ *      left = 0;
+ *      right = N - 1;    (rightmost stab)
+ *      stab_binsearch(stabs, &left, &right, type, addr);
+ *
+ * The search modifies *region_left and *region_right to bracket the @addr.
+ * *@region_left points to the matching stab that contains @addr,
+ * and *@region_right points just before the next stab.
+ * If *@region_left > *region_right, then @addr is not contained in any
+ * matching stab.
+ *
+ * For example, given these N_SO stabs:
+ *      Index  Type   Address
+ *      0      SO     f0100000
+ *      13     SO     f0100040
+ *      117    SO     f0100176
+ *      118    SO     f0100178
+ *      555    SO     f0100652
+ *      556    SO     f0100654
+ *      657    SO     f0100849
+ * this code:
+ *      left = 0, right = 657;
+ *      stab_binsearch(stabs, &left, &right, N_SO, 0xf0100184);
+ * will exit setting left = 118, right = 554.
+ * */
+static void
+stab_binsearch(const struct stab *stabs, int *region_left, int *region_right,
+           int type, uintptr_t addr) {
+    int l = *region_left, r = *region_right, any_matches = 0;
+
+    while (l <= r) {
+        int true_m = (l + r) / 2, m = true_m;
+
+        // search for earliest stab with right type
+        while (m >= l && stabs[m].n_type != type) {
+            m --;
+        }
+        if (m < l) {    // no match in [l, m]
+            l = true_m + 1;
+            continue;
+        }
+
+        // actual binary search
+        any_matches = 1;
+        if (stabs[m].n_value < addr) {
+            *region_left = m;
+            l = true_m + 1;
+        } else if (stabs[m].n_value > addr) {
+            *region_right = m - 1;
+            r = m - 1;
+        } else {
+            // exact match for 'addr', but continue loop to find
+            // *region_right
+            *region_left = m;
+            l = m;
+            addr ++;
+        }
+    }
+
+    if (!any_matches) {
+        *region_right = *region_left - 1;
+    }
+    else {
+        // find rightmost region containing 'addr'
+        l = *region_right;
+        for (; l > *region_left && stabs[l].n_type != type; l --)
+            /* do nothing */;
+        *region_left = l;
+    }
+}
+
+/* *
+ * debuginfo_eip - Fill in the @info structure with information about
+ * the specified instruction address, @addr.  Returns 0 if information
+ * was found, and negative if not.  But even if it returns negative it
+ * has stored some information into '*info'.
+ * */
+int
+debuginfo_eip(uintptr_t addr, struct eipdebuginfo *info) {
+    const struct stab *stabs, *stab_end;
+    const char *stabstr, *stabstr_end;
+
+    info->eip_file = "<unknown>";
+    info->eip_line = 0;
+    info->eip_fn_name = "<unknown>";
+    info->eip_fn_namelen = 9;
+    info->eip_fn_addr = addr;
+    info->eip_fn_narg = 0;
+
+    stabs = __STAB_BEGIN__;
+    stab_end = __STAB_END__;
+    stabstr = __STABSTR_BEGIN__;
+    stabstr_end = __STABSTR_END__;
+
+    // String table validity checks
+    if (stabstr_end <= stabstr || stabstr_end[-1] != 0) {
+        return -1;
+    }
+
+    // Now we find the right stabs that define the function containing
+    // 'eip'.  First, we find the basic source file containing 'eip'.
+    // Then, we look in that source file for the function.  Then we look
+    // for the line number.
+
+    // Search the entire set of stabs for the source file (type N_SO).
+    int lfile = 0, rfile = (stab_end - stabs) - 1;
+    stab_binsearch(stabs, &lfile, &rfile, N_SO, addr);
+    if (lfile == 0)
+        return -1;
+
+    // Search within that file's stabs for the function definition
+    // (N_FUN).
+    int lfun = lfile, rfun = rfile;
+    int lline, rline;
+    stab_binsearch(stabs, &lfun, &rfun, N_FUN, addr);
+
+    if (lfun <= rfun) {
+        // stabs[lfun] points to the function name
+        // in the string table, but check bounds just in case.
+        if (stabs[lfun].n_strx < stabstr_end - stabstr) {
+            info->eip_fn_name = stabstr + stabs[lfun].n_strx;
+        }
+        info->eip_fn_addr = stabs[lfun].n_value;
+        addr -= info->eip_fn_addr;
+        // Search within the function definition for the line number.
+        lline = lfun;
+        rline = rfun;
+    } else {
+        // Couldn't find function stab!  Maybe we're in an assembly
+        // file.  Search the whole file for the line number.
+        info->eip_fn_addr = addr;
+        lline = lfile;
+        rline = rfile;
+    }
+    info->eip_fn_namelen = strfind(info->eip_fn_name, ':') - info->eip_fn_name;
+
+    // Search within [lline, rline] for the line number stab.
+    // If found, set info->eip_line to the right line number.
+    // If not found, return -1.
+    stab_binsearch(stabs, &lline, &rline, N_SLINE, addr);
+    if (lline <= rline) {
+        info->eip_line = stabs[rline].n_desc;
+    } else {
+        return -1;
+    }
+
+    // Search backwards from the line number for the relevant filename stab.
+    // We can't just use the "lfile" stab because inlined functions
+    // can interpolate code from a different file!
+    // Such included source files use the N_SOL stab type.
+    while (lline >= lfile
+           && stabs[lline].n_type != N_SOL
+           && (stabs[lline].n_type != N_SO || !stabs[lline].n_value)) {
+        lline --;
+    }
+    if (lline >= lfile && stabs[lline].n_strx < stabstr_end - stabstr) {
+        info->eip_file = stabstr + stabs[lline].n_strx;
+    }
+
+    // Set eip_fn_narg to the number of arguments taken by the function,
+    // or 0 if there was no containing function.
+    if (lfun < rfun) {
+        for (lline = lfun + 1;
+             lline < rfun && stabs[lline].n_type == N_PSYM;
+             lline ++) {
+            info->eip_fn_narg ++;
+        }
+    }
+    return 0;
+}
+
+/* *
+ * print_kerninfo - print the information about kernel, including the location
+ * of kernel entry, the start addresses of data and text segements, the start
+ * address of free memory and how many memory that kernel has used.
+ * */
+void
+print_kerninfo(void) {
+    extern char etext[], edata[], end[], kern_init[];
+    cprintf("Special kernel symbols:\n");
+    cprintf("  entry  0x%08x (phys)\n", kern_init);
+    cprintf("  etext  0x%08x (phys)\n", etext);
+    cprintf("  edata  0x%08x (phys)\n", edata);
+    cprintf("  end    0x%08x (phys)\n", end);
+    cprintf("Kernel executable memory footprint: %dKB\n", (end - kern_init + 1023)/1024);
+}
+
+/* *
+ * print_debuginfo - read and print the stat information for the address @eip,
+ * and info.eip_fn_addr should be the first address of the related function.
+ * */
+void
+print_debuginfo(uintptr_t eip) {
+    struct eipdebuginfo info;
+    if (debuginfo_eip(eip, &info) != 0) {
+        cprintf("    <unknow>: -- 0x%08x --\n", eip);
+    }
+    else {
+        char fnname[256];
+        int j;
+        for (j = 0; j < info.eip_fn_namelen; j ++) {
+            fnname[j] = info.eip_fn_name[j];
+        }
+        fnname[j] = '\0';
+        cprintf("    %s:%d: %s+%d\n", info.eip_file, info.eip_line,
+                fnname, eip - info.eip_fn_addr);
+    }
+}
+
+static __noinline uint32_t
+read_eip(void) {
+    uint32_t eip;
+    asm volatile("movl 4(%%ebp), %0" : "=r" (eip));
+    return eip;
+}
+
+/* *
+ * print_stackframe - print a list of the saved eip values from the nested 'call'
+ * instructions that led to the current point of execution
+ *
+ * The x86 stack pointer, namely esp, points to the lowest location on the stack
+ * that is currently in use. Everything below that location in stack is free. Pushing
+ * a value onto the stack will invole decreasing the stack pointer and then writing
+ * the value to the place that stack pointer pointes to. And popping a value do the
+ * opposite.
+ *
+ * The ebp (base pointer) register, in contrast, is associated with the stack
+ * primarily by software convention. On entry to a C function, the function's
+ * prologue code normally saves the previous function's base pointer by pushing
+ * it onto the stack, and then copies the current esp value into ebp for the duration
+ * of the function. If all the functions in a program obey this convention,
+ * then at any given point during the program's execution, it is possible to trace
+ * back through the stack by following the chain of saved ebp pointers and determining
+ * exactly what nested sequence of function calls caused this particular point in the
+ * program to be reached. This capability can be particularly useful, for example,
+ * when a particular function causes an assert failure or panic because bad arguments
+ * were passed to it, but you aren't sure who passed the bad arguments. A stack
+ * backtrace lets you find the offending function.
+ *
+ * The inline function read_ebp() can tell us the value of current ebp. And the
+ * non-inline function read_eip() is useful, it can read the value of current eip,
+ * since while calling this function, read_eip() can read the caller's eip from
+ * stack easily.
+ *
+ * In print_debuginfo(), the function debuginfo_eip() can get enough information about
+ * calling-chain. Finally print_stackframe() will trace and print them for debugging.
+ *
+ * Note that, the length of ebp-chain is limited. In boot/bootasm.S, before jumping
+ * to the kernel entry, the value of ebp has been set to zero, that's the boundary.
+ * */
+void
+print_stackframe(void) {
+     /* LAB1 YOUR CODE : STEP 1 */
+     /* (1) call read_ebp() to get the value of ebp. the type is (uint32_t);
+      * (2) call read_eip() to get the value of eip. the type is (uint32_t);
+      * (3) from 0 .. STACKFRAME_DEPTH
+      *    (3.1) printf value of ebp, eip
+      *    (3.2) (uint32_t)calling arguments [0..4] = the contents in address (unit32_t)ebp +2 [0..4]
+      *    (3.3) cprintf("\n");
+      *    (3.4) call print_debuginfo(eip-1) to print the C calling function name and line number, etc.
+      *    (3.5) popup a calling stackframe
+      *           NOTICE: the calling funciton's return addr eip  = ss:[ebp+4]
+      *                   the calling funciton's ebp = ss:[ebp]
+      */
+    uint32_t ebp = read_ebp(), eip = read_eip();
+
+    int i, j;
+    for (i = 0; ebp != 0 && i < STACKFRAME_DEPTH; i ++) {
+        cprintf("ebp:0x%08x eip:0x%08x args:", ebp, eip);
+        uint32_t *args = (uint32_t *)ebp + 2;
+        for (j = 0; j < 4; j ++) {
+            cprintf("0x%08x ", args[j]);
+        }
+        cprintf("\n");
+        print_debuginfo(eip - 1);
+        eip = ((uint32_t *)ebp)[1];
+        ebp = ((uint32_t *)ebp)[0];
+    }
+}
+

labcodes_answer/lab1_result/kern/debug/kdebug.h

@@ -0,0 +1,11 @@
+#ifndef __KERN_DEBUG_KDEBUG_H__
+#define __KERN_DEBUG_KDEBUG_H__
+
+#include <defs.h>
+
+void print_kerninfo(void);
+void print_stackframe(void);
+void print_debuginfo(uintptr_t eip);
+
+#endif /* !__KERN_DEBUG_KDEBUG_H__ */
+

labcodes_answer/lab1_result/kern/debug/kmonitor.c

@@ -0,0 +1,128 @@
+#include <stdio.h>
+#include <string.h>
+#include <trap.h>
+#include <kmonitor.h>
+#include <kdebug.h>
+
+/* *
+ * Simple command-line kernel monitor useful for controlling the
+ * kernel and exploring the system interactively.
+ * */
+
+struct command {
+    const char *name;
+    const char *desc;
+    // return -1 to force monitor to exit
+    int(*func)(int argc, char **argv, struct trapframe *tf);
+};
+
+static struct command commands[] = {
+    {"help", "Display this list of commands.", mon_help},
+    {"kerninfo", "Display information about the kernel.", mon_kerninfo},
+    {"backtrace", "Print backtrace of stack frame.", mon_backtrace},
+};
+
+#define NCOMMANDS (sizeof(commands)/sizeof(struct command))
+
+/***** Kernel monitor command interpreter *****/
+
+#define MAXARGS         16
+#define WHITESPACE      " \t\n\r"
+
+/* parse - parse the command buffer into whitespace-separated arguments */
+static int
+parse(char *buf, char **argv) {
+    int argc = 0;
+    while (1) {
+        // find global whitespace
+        while (*buf != '\0' && strchr(WHITESPACE, *buf) != NULL) {
+            *buf ++ = '\0';
+        }
+        if (*buf == '\0') {
+            break;
+        }
+
+        // save and scan past next arg
+        if (argc == MAXARGS - 1) {
+            cprintf("Too many arguments (max %d).\n", MAXARGS);
+        }
+        argv[argc ++] = buf;
+        while (*buf != '\0' && strchr(WHITESPACE, *buf) == NULL) {
+            buf ++;
+        }
+    }
+    return argc;
+}
+
+/* *
+ * runcmd - parse the input string, split it into separated arguments
+ * and then lookup and invoke some related commands/
+ * */
+static int
+runcmd(char *buf, struct trapframe *tf) {
+    char *argv[MAXARGS];
+    int argc = parse(buf, argv);
+    if (argc == 0) {
+        return 0;
+    }
+    int i;
+    for (i = 0; i < NCOMMANDS; i ++) {
+        if (strcmp(commands[i].name, argv[0]) == 0) {
+            return commands[i].func(argc - 1, argv + 1, tf);
+        }
+    }
+    cprintf("Unknown command '%s'\n", argv[0]);
+    return 0;
+}
+
+/***** Implementations of basic kernel monitor commands *****/
+
+void
+kmonitor(struct trapframe *tf) {
+    cprintf("Welcome to the kernel debug monitor!!\n");
+    cprintf("Type 'help' for a list of commands.\n");
+
+    if (tf != NULL) {
+        print_trapframe(tf);
+    }
+
+    char *buf;
+    while (1) {
+        if ((buf = readline("K> ")) != NULL) {
+            if (runcmd(buf, tf) < 0) {
+                break;
+            }
+        }
+    }
+}
+
+/* mon_help - print the information about mon_* functions */
+int
+mon_help(int argc, char **argv, struct trapframe *tf) {
+    int i;
+    for (i = 0; i < NCOMMANDS; i ++) {
+        cprintf("%s - %s\n", commands[i].name, commands[i].desc);
+    }
+    return 0;
+}
+
+/* *
+ * mon_kerninfo - call print_kerninfo in kern/debug/kdebug.c to
+ * print the memory occupancy in kernel.
+ * */
+int
+mon_kerninfo(int argc, char **argv, struct trapframe *tf) {
+    print_kerninfo();
+    return 0;
+}
+
+/* *
+ * mon_backtrace - call print_stackframe in kern/debug/kdebug.c to
+ * print a backtrace of the stack.
+ * */
+int
+mon_backtrace(int argc, char **argv, struct trapframe *tf) {
+    print_stackframe();
+    return 0;
+}
+

labcodes_answer/lab1_result/kern/debug/kmonitor.h

@@ -0,0 +1,13 @@
+#ifndef __KERN_DEBUG_MONITOR_H__
+#define __KERN_DEBUG_MONITOR_H__
+
+#include <trap.h>
+
+void kmonitor(struct trapframe *tf);
+
+int mon_help(int argc, char **argv, struct trapframe *tf);
+int mon_kerninfo(int argc, char **argv, struct trapframe *tf);
+int mon_backtrace(int argc, char **argv, struct trapframe *tf);
+
+#endif /* !__KERN_DEBUG_MONITOR_H__ */
+

labcodes_answer/lab1_result/kern/debug/panic.c

@@ -0,0 +1,49 @@
+#include <defs.h>
+#include <stdio.h>
+#include <intr.h>
+#include <kmonitor.h>
+
+static bool is_panic = 0;
+
+/* *
+ * __panic - __panic is called on unresolvable fatal errors. it prints
+ * "panic: 'message'", and then enters the kernel monitor.
+ * */
+void
+__panic(const char *file, int line, const char *fmt, ...) {
+    if (is_panic) {
+        goto panic_dead;
+    }
+    is_panic = 1;
+
+    // print the 'message'
+    va_list ap;
+    va_start(ap, fmt);
+    cprintf("kernel panic at %s:%d:\n    ", file, line);
+    vcprintf(fmt, ap);
+    cprintf("\n");
+    va_end(ap);
+
+panic_dead:
+    intr_disable();
+    while (1) {
+        kmonitor(NULL);
+    }
+}
+
+/* __warn - like panic, but don't */
+void
+__warn(const char *file, int line, const char *fmt, ...) {
+    va_list ap;
+    va_start(ap, fmt);
+    cprintf("kernel warning at %s:%d:\n    ", file, line);
+    vcprintf(fmt, ap);
+    cprintf("\n");
+    va_end(ap);
+}
+
+bool
+is_kernel_panic(void) {
+    return is_panic;
+}
+

labcodes_answer/lab1_result/kern/debug/stab.h

@@ -0,0 +1,54 @@
+#ifndef __KERN_DEBUG_STAB_H__
+#define __KERN_DEBUG_STAB_H__
+
+#include <defs.h>
+
+/* *
+ * STABS debugging info
+ *
+ * The kernel debugger can understand some debugging information in
+ * the STABS format.  For more information on this format, see
+ * http://sources.redhat.com/gdb/onlinedocs/stabs_toc.html
+ *
+ * The constants below define some symbol types used by various debuggers
+ * and compilers.  Kernel uses the N_SO, N_SOL, N_FUN, and N_SLINE types.
+ * */
+
+#define N_GSYM      0x20    // global symbol
+#define N_FNAME     0x22    // F77 function name
+#define N_FUN       0x24    // procedure name
+#define N_STSYM     0x26    // data segment variable
+#define N_LCSYM     0x28    // bss segment variable
+#define N_MAIN      0x2a    // main function name
+#define N_PC        0x30    // global Pascal symbol
+#define N_RSYM      0x40    // register variable
+#define N_SLINE     0x44    // text segment line number
+#define N_DSLINE    0x46    // data segment line number
+#define N_BSLINE    0x48    // bss segment line number
+#define N_SSYM      0x60    // structure/union element
+#define N_SO        0x64    // main source file name
+#define N_LSYM      0x80    // stack variable
+#define N_BINCL     0x82    // include file beginning
+#define N_SOL       0x84    // included source file name
+#define N_PSYM      0xa0    // parameter variable
+#define N_EINCL     0xa2    // include file end
+#define N_ENTRY     0xa4    // alternate entry point
+#define N_LBRAC     0xc0    // left bracket
+#define N_EXCL      0xc2    // deleted include file
+#define N_RBRAC     0xe0    // right bracket
+#define N_BCOMM     0xe2    // begin common
+#define N_ECOMM     0xe4    // end common
+#define N_ECOML     0xe8    // end common (local name)
+#define N_LENG      0xfe    // length of preceding entry
+
+/* Entries in the STABS table are formatted as follows. */
+struct stab {
+    uint32_t n_strx;        // index into string table of name
+    uint8_t n_type;         // type of symbol
+    uint8_t n_other;        // misc info (usually empty)
+    uint16_t n_desc;        // description field
+    uintptr_t n_value;      // value of symbol
+};
+
+#endif /* !__KERN_DEBUG_STAB_H__ */
+

labcodes_answer/lab1_result/kern/driver/clock.c

@@ -0,0 +1,45 @@
+#include <x86.h>
+#include <trap.h>
+#include <stdio.h>
+#include <picirq.h>
+
+/* *
+ * Support for time-related hardware gadgets - the 8253 timer,
+ * which generates interruptes on IRQ-0.
+ * */
+
+#define IO_TIMER1           0x040               // 8253 Timer #1
+
+/* *
+ * Frequency of all three count-down timers; (TIMER_FREQ/freq)
+ * is the appropriate count to generate a frequency of freq Hz.
+ * */
+
+#define TIMER_FREQ      1193182
+#define TIMER_DIV(x)    ((TIMER_FREQ + (x) / 2) / (x))
+
+#define TIMER_MODE      (IO_TIMER1 + 3)         // timer mode port
+#define TIMER_SEL0      0x00                    // select counter 0
+#define TIMER_RATEGEN   0x04                    // mode 2, rate generator
+#define TIMER_16BIT     0x30                    // r/w counter 16 bits, LSB first
+
+volatile size_t ticks;
+
+/* *
+ * clock_init - initialize 8253 clock to interrupt 100 times per second,
+ * and then enable IRQ_TIMER.
+ * */
+void
+clock_init(void) {
+    // set 8253 timer-chip
+    outb(TIMER_MODE, TIMER_SEL0 | TIMER_RATEGEN | TIMER_16BIT);
+    outb(IO_TIMER1, TIMER_DIV(100) % 256);
+    outb(IO_TIMER1, TIMER_DIV(100) / 256);
+
+    // initialize time counter 'ticks' to zero
+    ticks = 0;
+
+    cprintf("++ setup timer interrupts\n");
+    pic_enable(IRQ_TIMER);
+}
+

labcodes_answer/lab1_result/kern/driver/clock.h

@@ -0,0 +1,11 @@
+#ifndef __KERN_DRIVER_CLOCK_H__
+#define __KERN_DRIVER_CLOCK_H__
+
+#include <defs.h>
+
+extern volatile size_t ticks;
+
+void clock_init(void);
+
+#endif /* !__KERN_DRIVER_CLOCK_H__ */
+

labcodes_answer/lab1_result/kern/driver/console.c

@@ -0,0 +1,455 @@
+#include <defs.h>
+#include <x86.h>
+#include <stdio.h>
+#include <string.h>
+#include <kbdreg.h>
+#include <picirq.h>
+#include <trap.h>
+
+/* stupid I/O delay routine necessitated by historical PC design flaws */
+static void
+delay(void) {
+    inb(0x84);
+    inb(0x84);
+    inb(0x84);
+    inb(0x84);
+}
+
+/***** Serial I/O code *****/
+#define COM1            0x3F8
+
+#define COM_RX          0       // In:  Receive buffer (DLAB=0)
+#define COM_TX          0       // Out: Transmit buffer (DLAB=0)
+#define COM_DLL         0       // Out: Divisor Latch Low (DLAB=1)
+#define COM_DLM         1       // Out: Divisor Latch High (DLAB=1)
+#define COM_IER         1       // Out: Interrupt Enable Register
+#define COM_IER_RDI     0x01    // Enable receiver data interrupt
+#define COM_IIR         2       // In:  Interrupt ID Register
+#define COM_FCR         2       // Out: FIFO Control Register
+#define COM_LCR         3       // Out: Line Control Register
+#define COM_LCR_DLAB    0x80    // Divisor latch access bit
+#define COM_LCR_WLEN8   0x03    // Wordlength: 8 bits
+#define COM_MCR         4       // Out: Modem Control Register
+#define COM_MCR_RTS     0x02    // RTS complement
+#define COM_MCR_DTR     0x01    // DTR complement
+#define COM_MCR_OUT2    0x08    // Out2 complement
+#define COM_LSR         5       // In:  Line Status Register
+#define COM_LSR_DATA    0x01    // Data available
+#define COM_LSR_TXRDY   0x20    // Transmit buffer avail
+#define COM_LSR_TSRE    0x40    // Transmitter off
+
+#define MONO_BASE       0x3B4
+#define MONO_BUF        0xB0000
+#define CGA_BASE        0x3D4
+#define CGA_BUF         0xB8000
+#define CRT_ROWS        25
+#define CRT_COLS        80
+#define CRT_SIZE        (CRT_ROWS * CRT_COLS)
+
+#define LPTPORT         0x378
+
+static uint16_t *crt_buf;
+static uint16_t crt_pos;
+static uint16_t addr_6845;
+
+/* TEXT-mode CGA/VGA display output */
+
+static void
+cga_init(void) {
+    volatile uint16_t *cp = (uint16_t *)CGA_BUF;
+    uint16_t was = *cp;
+    *cp = (uint16_t) 0xA55A;
+    if (*cp != 0xA55A) {
+        cp = (uint16_t*)MONO_BUF;
+        addr_6845 = MONO_BASE;
+    } else {
+        *cp = was;
+        addr_6845 = CGA_BASE;
+    }
+
+    // Extract cursor location
+    uint32_t pos;
+    outb(addr_6845, 14);
+    pos = inb(addr_6845 + 1) << 8;
+    outb(addr_6845, 15);
+    pos |= inb(addr_6845 + 1);
+
+    crt_buf = (uint16_t*) cp;
+    crt_pos = pos;
+}
+
+static bool serial_exists = 0;
+
+static void
+serial_init(void) {
+    // Turn off the FIFO
+    outb(COM1 + COM_FCR, 0);
+
+    // Set speed; requires DLAB latch
+    outb(COM1 + COM_LCR, COM_LCR_DLAB);
+    outb(COM1 + COM_DLL, (uint8_t) (115200 / 9600));
+    outb(COM1 + COM_DLM, 0);
+
+    // 8 data bits, 1 stop bit, parity off; turn off DLAB latch
+    outb(COM1 + COM_LCR, COM_LCR_WLEN8 & ~COM_LCR_DLAB);
+
+    // No modem controls
+    outb(COM1 + COM_MCR, 0);
+    // Enable rcv interrupts
+    outb(COM1 + COM_IER, COM_IER_RDI);
+
+    // Clear any preexisting overrun indications and interrupts
+    // Serial port doesn't exist if COM_LSR returns 0xFF
+    serial_exists = (inb(COM1 + COM_LSR) != 0xFF);
+    (void) inb(COM1+COM_IIR);
+    (void) inb(COM1+COM_RX);
+
+    if (serial_exists) {
+        pic_enable(IRQ_COM1);
+    }
+}
+
+static void
+lpt_putc_sub(int c) {
+    int i;
+    for (i = 0; !(inb(LPTPORT + 1) & 0x80) && i < 12800; i ++) {
+        delay();
+    }
+    outb(LPTPORT + 0, c);
+    outb(LPTPORT + 2, 0x08 | 0x04 | 0x01);
+    outb(LPTPORT + 2, 0x08);
+}
+
+/* lpt_putc - copy console output to parallel port */
+static void
+lpt_putc(int c) {
+    if (c != '\b') {
+        lpt_putc_sub(c);
+    }
+    else {
+        lpt_putc_sub('\b');
+        lpt_putc_sub(' ');
+        lpt_putc_sub('\b');
+    }
+}
+
+/* cga_putc - print character to console */
+static void
+cga_putc(int c) {
+    // set black on white
+    if (!(c & ~0xFF)) {
+        c |= 0x0700;
+    }
+
+    switch (c & 0xff) {
+    case '\b':
+        if (crt_pos > 0) {
+            crt_pos --;
+            crt_buf[crt_pos] = (c & ~0xff) | ' ';
+        }
+        break;
+    case '\n':
+        crt_pos += CRT_COLS;
+    case '\r':
+        crt_pos -= (crt_pos % CRT_COLS);
+        break;
+    default:
+        crt_buf[crt_pos ++] = c;     // write the character
+        break;
+    }
+
+    // What is the purpose of this?
+    if (crt_pos >= CRT_SIZE) {
+        int i;
+        memmove(crt_buf, crt_buf + CRT_COLS, (CRT_SIZE - CRT_COLS) * sizeof(uint16_t));
+        for (i = CRT_SIZE - CRT_COLS; i < CRT_SIZE; i ++) {
+            crt_buf[i] = 0x0700 | ' ';
+        }
+        crt_pos -= CRT_COLS;
+    }
+
+    // move that little blinky thing
+    outb(addr_6845, 14);
+    outb(addr_6845 + 1, crt_pos >> 8);
+    outb(addr_6845, 15);
+    outb(addr_6845 + 1, crt_pos);
+}
+
+static void
+serial_putc_sub(int c) {
+    int i;
+    for (i = 0; !(inb(COM1 + COM_LSR) & COM_LSR_TXRDY) && i < 12800; i ++) {
+        delay();
+    }
+    outb(COM1 + COM_TX, c);
+}
+
+/* serial_putc - print character to serial port */
+static void
+serial_putc(int c) {
+    if (c != '\b') {
+        serial_putc_sub(c);
+    }
+    else {
+        serial_putc_sub('\b');
+        serial_putc_sub(' ');
+        serial_putc_sub('\b');
+    }
+}
+
+/* *
+ * Here we manage the console input buffer, where we stash characters
+ * received from the keyboard or serial port whenever the corresponding
+ * interrupt occurs.
+ * */
+
+#define CONSBUFSIZE 512
+
+static struct {
+    uint8_t buf[CONSBUFSIZE];
+    uint32_t rpos;
+    uint32_t wpos;
+} cons;
+
+/* *
+ * cons_intr - called by device interrupt routines to feed input
+ * characters into the circular console input buffer.
+ * */
+static void
+cons_intr(int (*proc)(void)) {
+    int c;
+    while ((c = (*proc)()) != -1) {
+        if (c != 0) {
+            cons.buf[cons.wpos ++] = c;
+            if (cons.wpos == CONSBUFSIZE) {
+                cons.wpos = 0;
+            }
+        }
+    }
+}
+
+/* serial_proc_data - get data from serial port */
+static int
+serial_proc_data(void) {
+    if (!(inb(COM1 + COM_LSR) & COM_LSR_DATA)) {
+        return -1;
+    }
+    int c = inb(COM1 + COM_RX);
+    if (c == 127) {
+        c = '\b';
+    }
+    return c;
+}
+
+/* serial_intr - try to feed input characters from serial port */
+void
+serial_intr(void) {
+    if (serial_exists) {
+        cons_intr(serial_proc_data);
+    }
+}
+
+/***** Keyboard input code *****/
+
+#define NO              0
+
+#define SHIFT           (1<<0)
+#define CTL             (1<<1)
+#define ALT             (1<<2)
+
+#define CAPSLOCK        (1<<3)
+#define NUMLOCK         (1<<4)
+#define SCROLLLOCK      (1<<5)
+
+#define E0ESC           (1<<6)
+
+static uint8_t shiftcode[256] = {
+    [0x1D] CTL,
+    [0x2A] SHIFT,
+    [0x36] SHIFT,
+    [0x38] ALT,
+    [0x9D] CTL,
+    [0xB8] ALT
+};
+
+static uint8_t togglecode[256] = {
+    [0x3A] CAPSLOCK,
+    [0x45] NUMLOCK,
+    [0x46] SCROLLLOCK
+};
+
+static uint8_t normalmap[256] = {
+    NO,   0x1B, '1',  '2',  '3',  '4',  '5',  '6',  // 0x00
+    '7',  '8',  '9',  '0',  '-',  '=',  '\b', '\t',
+    'q',  'w',  'e',  'r',  't',  'y',  'u',  'i',  // 0x10
+    'o',  'p',  '[',  ']',  '\n', NO,   'a',  's',
+    'd',  'f',  'g',  'h',  'j',  'k',  'l',  ';',  // 0x20
+    '\'', '`',  NO,   '\\', 'z',  'x',  'c',  'v',
+    'b',  'n',  'm',  ',',  '.',  '/',  NO,   '*',  // 0x30
+    NO,   ' ',  NO,   NO,   NO,   NO,   NO,   NO,
+    NO,   NO,   NO,   NO,   NO,   NO,   NO,   '7',  // 0x40
+    '8',  '9',  '-',  '4',  '5',  '6',  '+',  '1',
+    '2',  '3',  '0',  '.',  NO,   NO,   NO,   NO,   // 0x50
+    [0xC7] KEY_HOME,    [0x9C] '\n' /*KP_Enter*/,
+    [0xB5] '/' /*KP_Div*/,  [0xC8] KEY_UP,
+    [0xC9] KEY_PGUP,    [0xCB] KEY_LF,
+    [0xCD] KEY_RT,      [0xCF] KEY_END,
+    [0xD0] KEY_DN,      [0xD1] KEY_PGDN,
+    [0xD2] KEY_INS,     [0xD3] KEY_DEL
+};
+
+static uint8_t shiftmap[256] = {
+    NO,   033,  '!',  '@',  '#',  '$',  '%',  '^',  // 0x00
+    '&',  '*',  '(',  ')',  '_',  '+',  '\b', '\t',
+    'Q',  'W',  'E',  'R',  'T',  'Y',  'U',  'I',  // 0x10
+    'O',  'P',  '{',  '}',  '\n', NO,   'A',  'S',
+    'D',  'F',  'G',  'H',  'J',  'K',  'L',  ':',  // 0x20
+    '"',  '~',  NO,   '|',  'Z',  'X',  'C',  'V',
+    'B',  'N',  'M',  '<',  '>',  '?',  NO,   '*',  // 0x30
+    NO,   ' ',  NO,   NO,   NO,   NO,   NO,   NO,
+    NO,   NO,   NO,   NO,   NO,   NO,   NO,   '7',  // 0x40
+    '8',  '9',  '-',  '4',  '5',  '6',  '+',  '1',
+    '2',  '3',  '0',  '.',  NO,   NO,   NO,   NO,   // 0x50
+    [0xC7] KEY_HOME,    [0x9C] '\n' /*KP_Enter*/,
+    [0xB5] '/' /*KP_Div*/,  [0xC8] KEY_UP,
+    [0xC9] KEY_PGUP,    [0xCB] KEY_LF,
+    [0xCD] KEY_RT,      [0xCF] KEY_END,
+    [0xD0] KEY_DN,      [0xD1] KEY_PGDN,
+    [0xD2] KEY_INS,     [0xD3] KEY_DEL
+};
+
+#define C(x) (x - '@')
+
+static uint8_t ctlmap[256] = {
+    NO,      NO,      NO,      NO,      NO,      NO,      NO,      NO,
+    NO,      NO,      NO,      NO,      NO,      NO,      NO,      NO,
+    C('Q'),  C('W'),  C('E'),  C('R'),  C('T'),  C('Y'),  C('U'),  C('I'),
+    C('O'),  C('P'),  NO,      NO,      '\r',    NO,      C('A'),  C('S'),
+    C('D'),  C('F'),  C('G'),  C('H'),  C('J'),  C('K'),  C('L'),  NO,
+    NO,      NO,      NO,      C('\\'), C('Z'),  C('X'),  C('C'),  C('V'),
+    C('B'),  C('N'),  C('M'),  NO,      NO,      C('/'),  NO,      NO,
+    [0x97] KEY_HOME,
+    [0xB5] C('/'),      [0xC8] KEY_UP,
+    [0xC9] KEY_PGUP,    [0xCB] KEY_LF,
+    [0xCD] KEY_RT,      [0xCF] KEY_END,
+    [0xD0] KEY_DN,      [0xD1] KEY_PGDN,
+    [0xD2] KEY_INS,     [0xD3] KEY_DEL
+};
+
+static uint8_t *charcode[4] = {
+    normalmap,
+    shiftmap,
+    ctlmap,
+    ctlmap
+};
+
+/* *
+ * kbd_proc_data - get data from keyboard
+ *
+ * The kbd_proc_data() function gets data from the keyboard.
+ * If we finish a character, return it, else 0. And return -1 if no data.
+ * */
+static int
+kbd_proc_data(void) {
+    int c;
+    uint8_t data;
+    static uint32_t shift;
+
+    if ((inb(KBSTATP) & KBS_DIB) == 0) {
+        return -1;
+    }
+
+    data = inb(KBDATAP);
+
+    if (data == 0xE0) {
+        // E0 escape character
+        shift |= E0ESC;
+        return 0;
+    } else if (data & 0x80) {
+        // Key released
+        data = (shift & E0ESC ? data : data & 0x7F);
+        shift &= ~(shiftcode[data] | E0ESC);
+        return 0;
+    } else if (shift & E0ESC) {
+        // Last character was an E0 escape; or with 0x80
+        data |= 0x80;
+        shift &= ~E0ESC;
+    }
+
+    shift |= shiftcode[data];
+    shift ^= togglecode[data];
+
+    c = charcode[shift & (CTL | SHIFT)][data];
+    if (shift & CAPSLOCK) {
+        if ('a' <= c && c <= 'z')
+            c += 'A' - 'a';
+        else if ('A' <= c && c <= 'Z')
+            c += 'a' - 'A';
+    }
+
+    // Process special keys
+    // Ctrl-Alt-Del: reboot
+    if (!(~shift & (CTL | ALT)) && c == KEY_DEL) {
+        cprintf("Rebooting!\n");
+        outb(0x92, 0x3); // courtesy of Chris Frost
+    }
+    return c;
+}
+
+/* kbd_intr - try to feed input characters from keyboard */
+static void
+kbd_intr(void) {
+    cons_intr(kbd_proc_data);
+}
+
+static void
+kbd_init(void) {
+    // drain the kbd buffer
+    kbd_intr();
+    pic_enable(IRQ_KBD);
+}
+
+/* cons_init - initializes the console devices */
+void
+cons_init(void) {
+    cga_init();
+    serial_init();
+    kbd_init();
+    if (!serial_exists) {
+        cprintf("serial port does not exist!!\n");
+    }
+}
+
+/* cons_putc - print a single character @c to console devices */
+void
+cons_putc(int c) {
+    lpt_putc(c);
+    cga_putc(c);
+    serial_putc(c);
+}
+
+/* *
+ * cons_getc - return the next input character from console,
+ * or 0 if none waiting.
+ * */
+int
+cons_getc(void) {
+    int c;
+
+    // poll for any pending input characters,
+    // so that this function works even when interrupts are disabled
+    // (e.g., when called from the kernel monitor).
+    serial_intr();
+    kbd_intr();
+
+    // grab the next character from the input buffer.
+    if (cons.rpos != cons.wpos) {
+        c = cons.buf[cons.rpos ++];
+        if (cons.rpos == CONSBUFSIZE) {
+            cons.rpos = 0;
+        }
+        return c;
+    }
+    return 0;
+}
+

labcodes_answer/lab1_result/kern/driver/console.h

@@ -0,0 +1,11 @@
+#ifndef __KERN_DRIVER_CONSOLE_H__
+#define __KERN_DRIVER_CONSOLE_H__
+
+void cons_init(void);
+void cons_putc(int c);
+int cons_getc(void);
+void serial_intr(void);
+void kbd_intr(void);
+
+#endif /* !__KERN_DRIVER_CONSOLE_H__ */
+

labcodes_answer/lab1_result/kern/driver/intr.c

@@ -0,0 +1,15 @@
+#include <x86.h>
+#include <intr.h>
+
+/* intr_enable - enable irq interrupt */
+void
+intr_enable(void) {
+    sti();
+}
+
+/* intr_disable - disable irq interrupt */
+void
+intr_disable(void) {
+    cli();
+}
+

labcodes_answer/lab1_result/kern/driver/intr.h

@@ -0,0 +1,8 @@
+#ifndef __KERN_DRIVER_INTR_H__
+#define __KERN_DRIVER_INTR_H__
+
+void intr_enable(void);
+void intr_disable(void);
+
+#endif /* !__KERN_DRIVER_INTR_H__ */
+

labcodes_answer/lab1_result/kern/driver/kbdreg.h

@@ -0,0 +1,84 @@
+#ifndef __KERN_DRIVER_KBDREG_H__
+#define __KERN_DRIVER_KBDREG_H__
+
+// Special keycodes
+#define KEY_HOME            0xE0
+#define KEY_END             0xE1
+#define KEY_UP              0xE2
+#define KEY_DN              0xE3
+#define KEY_LF              0xE4
+#define KEY_RT              0xE5
+#define KEY_PGUP            0xE6
+#define KEY_PGDN            0xE7
+#define KEY_INS             0xE8
+#define KEY_DEL             0xE9
+
+
+/* This is i8042reg.h + kbdreg.h from NetBSD. */
+
+#define KBSTATP             0x64    // kbd controller status port(I)
+#define KBS_DIB             0x01    // kbd data in buffer
+#define KBS_IBF             0x02    // kbd input buffer low
+#define KBS_WARM            0x04    // kbd input buffer low
+#define BS_OCMD             0x08    // kbd output buffer has command
+#define KBS_NOSEC           0x10    // kbd security lock not engaged
+#define KBS_TERR            0x20    // kbd transmission error
+#define KBS_RERR            0x40    // kbd receive error
+#define KBS_PERR            0x80    // kbd parity error
+
+#define KBCMDP              0x64    // kbd controller port(O)
+#define KBC_RAMREAD         0x20    // read from RAM
+#define KBC_RAMWRITE        0x60    // write to RAM
+#define KBC_AUXDISABLE      0xa7    // disable auxiliary port
+#define KBC_AUXENABLE       0xa8    // enable auxiliary port
+#define KBC_AUXTEST         0xa9    // test auxiliary port
+#define KBC_KBDECHO         0xd2    // echo to keyboard port
+#define KBC_AUXECHO         0xd3    // echo to auxiliary port
+#define KBC_AUXWRITE        0xd4    // write to auxiliary port
+#define KBC_SELFTEST        0xaa    // start self-test
+#define KBC_KBDTEST         0xab    // test keyboard port
+#define KBC_KBDDISABLE      0xad    // disable keyboard port
+#define KBC_KBDENABLE       0xae    // enable keyboard port
+#define KBC_PULSE0          0xfe    // pulse output bit 0
+#define KBC_PULSE1          0xfd    // pulse output bit 1
+#define KBC_PULSE2          0xfb    // pulse output bit 2
+#define KBC_PULSE3          0xf7    // pulse output bit 3
+
+#define KBDATAP             0x60    // kbd data port(I)
+#define KBOUTP              0x60    // kbd data port(O)
+
+#define K_RDCMDBYTE         0x20
+#define K_LDCMDBYTE         0x60
+
+#define KC8_TRANS           0x40    // convert to old scan codes
+#define KC8_MDISABLE        0x20    // disable mouse
+#define KC8_KDISABLE        0x10    // disable keyboard
+#define KC8_IGNSEC          0x08    // ignore security lock
+#define KC8_CPU             0x04    // exit from protected mode reset
+#define KC8_MENABLE         0x02    // enable mouse interrupt
+#define KC8_KENABLE         0x01    // enable keyboard interrupt
+#define CMDBYTE             (KC8_TRANS|KC8_CPU|KC8_MENABLE|KC8_KENABLE)
+
+/* keyboard commands */
+#define KBC_RESET           0xFF    // reset the keyboard
+#define KBC_RESEND          0xFE    // request the keyboard resend the last byte
+#define KBC_SETDEFAULT      0xF6    // resets keyboard to its power-on defaults
+#define KBC_DISABLE         0xF5    // as per KBC_SETDEFAULT, but also disable key scanning
+#define KBC_ENABLE          0xF4    // enable key scanning
+#define KBC_TYPEMATIC       0xF3    // set typematic rate and delay
+#define KBC_SETTABLE        0xF0    // set scancode translation table
+#define KBC_MODEIND         0xED    // set mode indicators(i.e. LEDs)
+#define KBC_ECHO            0xEE    // request an echo from the keyboard
+
+/* keyboard responses */
+#define KBR_EXTENDED        0xE0    // extended key sequence
+#define KBR_RESEND          0xFE    // needs resend of command
+#define KBR_ACK             0xFA    // received a valid command
+#define KBR_OVERRUN         0x00    // flooded
+#define KBR_FAILURE         0xFD    // diagnosic failure
+#define KBR_BREAK           0xF0    // break code prefix - sent on key release
+#define KBR_RSTDONE         0xAA    // reset complete
+#define KBR_ECHO            0xEE    // echo response
+
+#endif /* !__KERN_DRIVER_KBDREG_H__ */
+

labcodes_answer/lab1_result/kern/driver/picirq.c

@@ -0,0 +1,86 @@
+#include <defs.h>
+#include <x86.h>
+#include <picirq.h>
+
+// I/O Addresses of the two programmable interrupt controllers
+#define IO_PIC1             0x20    // Master (IRQs 0-7)
+#define IO_PIC2             0xA0    // Slave (IRQs 8-15)
+
+#define IRQ_SLAVE           2       // IRQ at which slave connects to master
+
+// Current IRQ mask.
+// Initial IRQ mask has interrupt 2 enabled (for slave 8259A).
+static uint16_t irq_mask = 0xFFFF & ~(1 << IRQ_SLAVE);
+static bool did_init = 0;
+
+static void
+pic_setmask(uint16_t mask) {
+    irq_mask = mask;
+    if (did_init) {
+        outb(IO_PIC1 + 1, mask);
+        outb(IO_PIC2 + 1, mask >> 8);
+    }
+}
+
+void
+pic_enable(unsigned int irq) {
+    pic_setmask(irq_mask & ~(1 << irq));
+}
+
+/* pic_init - initialize the 8259A interrupt controllers */
+void
+pic_init(void) {
+    did_init = 1;
+
+    // mask all interrupts
+    outb(IO_PIC1 + 1, 0xFF);
+    outb(IO_PIC2 + 1, 0xFF);
+
+    // Set up master (8259A-1)
+
+    // ICW1:  0001g0hi
+    //    g:  0 = edge triggering, 1 = level triggering
+    //    h:  0 = cascaded PICs, 1 = master only
+    //    i:  0 = no ICW4, 1 = ICW4 required
+    outb(IO_PIC1, 0x11);
+
+    // ICW2:  Vector offset
+    outb(IO_PIC1 + 1, IRQ_OFFSET);
+
+    // ICW3:  (master PIC) bit mask of IR lines connected to slaves
+    //        (slave PIC) 3-bit # of slave's connection to master
+    outb(IO_PIC1 + 1, 1 << IRQ_SLAVE);
+
+    // ICW4:  000nbmap
+    //    n:  1 = special fully nested mode
+    //    b:  1 = buffered mode
+    //    m:  0 = slave PIC, 1 = master PIC
+    //        (ignored when b is 0, as the master/slave role
+    //         can be hardwired).
+    //    a:  1 = Automatic EOI mode
+    //    p:  0 = MCS-80/85 mode, 1 = intel x86 mode
+    outb(IO_PIC1 + 1, 0x3);
+
+    // Set up slave (8259A-2)
+    outb(IO_PIC2, 0x11);    // ICW1
+    outb(IO_PIC2 + 1, IRQ_OFFSET + 8);  // ICW2
+    outb(IO_PIC2 + 1, IRQ_SLAVE);       // ICW3
+    // NB Automatic EOI mode doesn't tend to work on the slave.
+    // Linux source code says it's "to be investigated".
+    outb(IO_PIC2 + 1, 0x3);             // ICW4
+
+    // OCW3:  0ef01prs
+    //   ef:  0x = NOP, 10 = clear specific mask, 11 = set specific mask
+    //    p:  0 = no polling, 1 = polling mode
+    //   rs:  0x = NOP, 10 = read IRR, 11 = read ISR
+    outb(IO_PIC1, 0x68);    // clear specific mask
+    outb(IO_PIC1, 0x0a);    // read IRR by default
+
+    outb(IO_PIC2, 0x68);    // OCW3
+    outb(IO_PIC2, 0x0a);    // OCW3
+
+    if (irq_mask != 0xFFFF) {
+        pic_setmask(irq_mask);
+    }
+}
+

labcodes_answer/lab1_result/kern/driver/picirq.h

@@ -0,0 +1,10 @@
+#ifndef __KERN_DRIVER_PICIRQ_H__
+#define __KERN_DRIVER_PICIRQ_H__
+
+void pic_init(void);
+void pic_enable(unsigned int irq);
+
+#define IRQ_OFFSET      32
+
+#endif /* !__KERN_DRIVER_PICIRQ_H__ */
+

labcodes_answer/lab1_result/kern/init/init.c

@@ -0,0 +1,104 @@
+#include <defs.h>
+#include <stdio.h>
+#include <string.h>
+#include <console.h>
+#include <kdebug.h>
+#include <picirq.h>
+#include <trap.h>
+#include <clock.h>
+#include <intr.h>
+#include <pmm.h>
+
+int kern_init(void) __attribute__((noreturn));
+
+static void lab1_switch_test(void);
+
+int
+kern_init(void) {
+    extern char edata[], end[];
+    memset(edata, 0, end - edata);
+
+    cons_init();                // init the console
+
+    const char *message = "(THU.CST) os is loading ...";
+    cprintf("%s\n\n", message);
+
+    print_kerninfo();
+
+    grade_backtrace();
+
+    pmm_init();                 // init physical memory management
+
+    pic_init();                 // init interrupt controller
+    idt_init();                 // init interrupt descriptor table
+
+    clock_init();               // init clock interrupt
+    intr_enable();              // enable irq interrupt
+
+    //LAB1: CAHLLENGE 1 If you try to do it, uncomment lab1_switch_test()
+    // user/kernel mode switch test
+    //lab1_switch_test();
+
+    /* do nothing */
+    while (1);
+}
+
+void __attribute__((noinline))
+grade_backtrace2(int arg0, int arg1, int arg2, int arg3) {
+    mon_backtrace(0, NULL, NULL);
+}
+
+void __attribute__((noinline))
+grade_backtrace1(int arg0, int arg1) {
+    grade_backtrace2(arg0, (int)&arg0, arg1, (int)&arg1);
+}
+
+void __attribute__((noinline))
+grade_backtrace0(int arg0, int arg1, int arg2) {
+    grade_backtrace1(arg0, arg2);
+}
+
+void
+grade_backtrace(void) {
+    grade_backtrace0(0, (int)kern_init, 0xffff0000);
+}
+
+static void
+lab1_print_cur_status(void) {
+    static int round = 0;
+    uint16_t reg1, reg2, reg3, reg4;
+    asm volatile (
+            "mov %%cs, %0;"
+            "mov %%ds, %1;"
+            "mov %%es, %2;"
+            "mov %%ss, %3;"
+            : "=m"(reg1), "=m"(reg2), "=m"(reg3), "=m"(reg4));
+    cprintf("%d: @ring %d\n", round, reg1 & 3);
+    cprintf("%d:  cs = %x\n", round, reg1);
+    cprintf("%d:  ds = %x\n", round, reg2);
+    cprintf("%d:  es = %x\n", round, reg3);
+    cprintf("%d:  ss = %x\n", round, reg4);
+    round ++;
+}
+
+static void
+lab1_switch_to_user(void) {
+    //LAB1 CHALLENGE 1 : TODO
+}
+
+static void
+lab1_switch_to_kernel(void) {
+    //LAB1 CHALLENGE 1 :  TODO
+}
+
+static void
+lab1_switch_test(void) {
+    lab1_print_cur_status();
+    cprintf("+++ switch to  user  mode +++\n");
+    lab1_switch_to_user();
+    lab1_print_cur_status();
+    cprintf("+++ switch to kernel mode +++\n");
+    lab1_switch_to_kernel();
+    lab1_print_cur_status();
+}
+

labcodes_answer/lab1_result/kern/libs/readline.c

@@ -0,0 +1,50 @@
+#include <stdio.h>
+
+#define BUFSIZE    1024
+static char buf[BUFSIZE];
+
+/* *
+ * readline - get a line from stdin
+ * @prompt:        the string to be written to stdout
+ *
+ * The readline() function will write the input string @prompt to
+ * stdout first. If the @prompt is NULL or the empty string,
+ * no prompt is issued.
+ *
+ * This function will keep on reading characters and saving them to buffer
+ * 'buf' until '\n' or '\r' is encountered.
+ *
+ * Note that, if the length of string that will be read is longer than
+ * buffer size, the end of string will be discarded.
+ *
+ * The readline() function returns the text of the line read. If some errors
+ * are happened, NULL is returned. The return value is a global variable,
+ * thus it should be copied before it is used.
+ * */
+char *
+readline(const char *prompt) {
+    if (prompt != NULL) {
+        cprintf("%s", prompt);
+    }
+    int i = 0, c;
+    while (1) {
+        c = getchar();
+        if (c < 0) {
+            return NULL;
+        }
+        else if (c >= ' ' && i < BUFSIZE - 1) {
+            cputchar(c);
+            buf[i ++] = c;
+        }
+        else if (c == '\b' && i > 0) {
+            cputchar(c);
+            i --;
+        }
+        else if (c == '\n' || c == '\r') {
+            cputchar(c);
+            buf[i] = '\0';
+            return buf;
+        }
+    }
+}
+

labcodes_answer/lab1_result/kern/libs/stdio.c

@@ -0,0 +1,78 @@
+#include <defs.h>
+#include <stdio.h>
+#include <console.h>
+
+/* HIGH level console I/O */
+
+/* *
+ * cputch - writes a single character @c to stdout, and it will
+ * increace the value of counter pointed by @cnt.
+ * */
+static void
+cputch(int c, int *cnt) {
+    cons_putc(c);
+    (*cnt) ++;
+}
+
+/* *
+ * vcprintf - format a string and writes it to stdout
+ *
+ * The return value is the number of characters which would be
+ * written to stdout.
+ *
+ * Call this function if you are already dealing with a va_list.
+ * Or you probably want cprintf() instead.
+ * */
+int
+vcprintf(const char *fmt, va_list ap) {
+    int cnt = 0;
+    vprintfmt((void*)cputch, &cnt, fmt, ap);
+    return cnt;
+}
+
+/* *
+ * cprintf - formats a string and writes it to stdout
+ *
+ * The return value is the number of characters which would be
+ * written to stdout.
+ * */
+int
+cprintf(const char *fmt, ...) {
+    va_list ap;
+    int cnt;
+    va_start(ap, fmt);
+    cnt = vcprintf(fmt, ap);
+    va_end(ap);
+    return cnt;
+}
+
+/* cputchar - writes a single character to stdout */
+void
+cputchar(int c) {
+    cons_putc(c);
+}
+
+/* *
+ * cputs- writes the string pointed by @str to stdout and
+ * appends a newline character.
+ * */
+int
+cputs(const char *str) {
+    int cnt = 0;
+    char c;
+    while ((c = *str ++) != '\0') {
+        cputch(c, &cnt);
+    }
+    cputch('\n', &cnt);
+    return cnt;
+}
+
+/* getchar - reads a single non-zero character from stdin */
+int
+getchar(void) {
+    int c;
+    while ((c = cons_getc()) == 0)
+        /* do nothing */;
+    return c;
+}
+

labcodes_answer/lab1_result/kern/mm/memlayout.h

@@ -0,0 +1,29 @@
+#ifndef __KERN_MM_MEMLAYOUT_H__
+#define __KERN_MM_MEMLAYOUT_H__
+
+/* This file contains the definitions for memory management in our OS. */
+
+/* global segment number */
+#define SEG_KTEXT    1
+#define SEG_KDATA    2
+#define SEG_UTEXT    3
+#define SEG_UDATA    4
+#define SEG_TSS        5
+
+/* global descrptor numbers */
+#define GD_KTEXT    ((SEG_KTEXT) << 3)        // kernel text
+#define GD_KDATA    ((SEG_KDATA) << 3)        // kernel data
+#define GD_UTEXT    ((SEG_UTEXT) << 3)        // user text
+#define GD_UDATA    ((SEG_UDATA) << 3)        // user data
+#define GD_TSS        ((SEG_TSS) << 3)        // task segment selector
+
+#define DPL_KERNEL    (0)
+#define DPL_USER    (3)
+
+#define KERNEL_CS    ((GD_KTEXT) | DPL_KERNEL)
+#define KERNEL_DS    ((GD_KDATA) | DPL_KERNEL)
+#define USER_CS        ((GD_UTEXT) | DPL_USER)
+#define USER_DS        ((GD_UDATA) | DPL_USER)
+
+#endif /* !__KERN_MM_MEMLAYOUT_H__ */
+

labcodes_answer/lab1_result/kern/mm/mmu.h

@@ -0,0 +1,174 @@
+#ifndef __KERN_MM_MMU_H__
+#define __KERN_MM_MMU_H__
+
+/* Eflags register */
+#define FL_CF            0x00000001    // Carry Flag
+#define FL_PF            0x00000004    // Parity Flag
+#define FL_AF            0x00000010    // Auxiliary carry Flag
+#define FL_ZF            0x00000040    // Zero Flag
+#define FL_SF            0x00000080    // Sign Flag
+#define FL_TF            0x00000100    // Trap Flag
+#define FL_IF            0x00000200    // Interrupt Flag
+#define FL_DF            0x00000400    // Direction Flag
+#define FL_OF            0x00000800    // Overflow Flag
+#define FL_IOPL_MASK    0x00003000    // I/O Privilege Level bitmask
+#define FL_IOPL_0        0x00000000    //   IOPL == 0
+#define FL_IOPL_1        0x00001000    //   IOPL == 1
+#define FL_IOPL_2        0x00002000    //   IOPL == 2
+#define FL_IOPL_3        0x00003000    //   IOPL == 3
+#define FL_NT            0x00004000    // Nested Task
+#define FL_RF            0x00010000    // Resume Flag
+#define FL_VM            0x00020000    // Virtual 8086 mode
+#define FL_AC            0x00040000    // Alignment Check
+#define FL_VIF            0x00080000    // Virtual Interrupt Flag
+#define FL_VIP            0x00100000    // Virtual Interrupt Pending
+#define FL_ID            0x00200000    // ID flag
+
+/* Application segment type bits */
+#define STA_X            0x8            // Executable segment
+#define STA_E            0x4            // Expand down (non-executable segments)
+#define STA_C            0x4            // Conforming code segment (executable only)
+#define STA_W            0x2            // Writeable (non-executable segments)
+#define STA_R            0x2            // Readable (executable segments)
+#define STA_A            0x1            // Accessed
+
+/* System segment type bits */
+#define STS_T16A        0x1            // Available 16-bit TSS
+#define STS_LDT            0x2            // Local Descriptor Table
+#define STS_T16B        0x3            // Busy 16-bit TSS
+#define STS_CG16        0x4            // 16-bit Call Gate
+#define STS_TG            0x5            // Task Gate / Coum Transmitions
+#define STS_IG16        0x6            // 16-bit Interrupt Gate
+#define STS_TG16        0x7            // 16-bit Trap Gate
+#define STS_T32A        0x9            // Available 32-bit TSS
+#define STS_T32B        0xB            // Busy 32-bit TSS
+#define STS_CG32        0xC            // 32-bit Call Gate
+#define STS_IG32        0xE            // 32-bit Interrupt Gate
+#define STS_TG32        0xF            // 32-bit Trap Gate
+
+/* Gate descriptors for interrupts and traps */
+struct gatedesc {
+    unsigned gd_off_15_0 : 16;        // low 16 bits of offset in segment
+    unsigned gd_ss : 16;            // segment selector
+    unsigned gd_args : 5;            // # args, 0 for interrupt/trap gates
+    unsigned gd_rsv1 : 3;            // reserved(should be zero I guess)
+    unsigned gd_type : 4;            // type(STS_{TG,IG32,TG32})
+    unsigned gd_s : 1;                // must be 0 (system)
+    unsigned gd_dpl : 2;            // descriptor(meaning new) privilege level
+    unsigned gd_p : 1;                // Present
+    unsigned gd_off_31_16 : 16;        // high bits of offset in segment
+};
+
+/* *
+ * Set up a normal interrupt/trap gate descriptor
+ *   - istrap: 1 for a trap (= exception) gate, 0 for an interrupt gate
+ *   - sel: Code segment selector for interrupt/trap handler
+ *   - off: Offset in code segment for interrupt/trap handler
+ *   - dpl: Descriptor Privilege Level - the privilege level required
+ *          for software to invoke this interrupt/trap gate explicitly
+ *          using an int instruction.
+ * */
+#define SETGATE(gate, istrap, sel, off, dpl) {            \
+    (gate).gd_off_15_0 = (uint32_t)(off) & 0xffff;        \
+    (gate).gd_ss = (sel);                                \
+    (gate).gd_args = 0;                                    \
+    (gate).gd_rsv1 = 0;                                    \
+    (gate).gd_type = (istrap) ? STS_TG32 : STS_IG32;    \
+    (gate).gd_s = 0;                                    \
+    (gate).gd_dpl = (dpl);                                \
+    (gate).gd_p = 1;                                    \
+    (gate).gd_off_31_16 = (uint32_t)(off) >> 16;        \
+}
+
+/* Set up a call gate descriptor */
+#define SETCALLGATE(gate, ss, off, dpl) {                \
+    (gate).gd_off_15_0 = (uint32_t)(off) & 0xffff;        \
+    (gate).gd_ss = (ss);                                \
+    (gate).gd_args = 0;                                    \
+    (gate).gd_rsv1 = 0;                                    \
+    (gate).gd_type = STS_CG32;                            \
+    (gate).gd_s = 0;                                    \
+    (gate).gd_dpl = (dpl);                                \
+    (gate).gd_p = 1;                                    \
+    (gate).gd_off_31_16 = (uint32_t)(off) >> 16;        \
+}
+
+/* segment descriptors */
+struct segdesc {
+    unsigned sd_lim_15_0 : 16;        // low bits of segment limit
+    unsigned sd_base_15_0 : 16;        // low bits of segment base address
+    unsigned sd_base_23_16 : 8;        // middle bits of segment base address
+    unsigned sd_type : 4;            // segment type (see STS_ constants)
+    unsigned sd_s : 1;                // 0 = system, 1 = application
+    unsigned sd_dpl : 2;            // descriptor Privilege Level
+    unsigned sd_p : 1;                // present
+    unsigned sd_lim_19_16 : 4;        // high bits of segment limit
+    unsigned sd_avl : 1;            // unused (available for software use)
+    unsigned sd_rsv1 : 1;            // reserved
+    unsigned sd_db : 1;                // 0 = 16-bit segment, 1 = 32-bit segment
+    unsigned sd_g : 1;                // granularity: limit scaled by 4K when set
+    unsigned sd_base_31_24 : 8;        // high bits of segment base address
+};
+
+#define SEG_NULL                                            \
+    (struct segdesc){0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
+
+#define SEG(type, base, lim, dpl)                        \
+    (struct segdesc){                                    \
+        ((lim) >> 12) & 0xffff, (base) & 0xffff,        \
+        ((base) >> 16) & 0xff, type, 1, dpl, 1,            \
+        (unsigned)(lim) >> 28, 0, 0, 1, 1,                \
+        (unsigned) (base) >> 24                            \
+    }
+
+#define SEG16(type, base, lim, dpl)                        \
+    (struct segdesc){                                    \
+        (lim) & 0xffff, (base) & 0xffff,                \
+        ((base) >> 16) & 0xff, type, 1, dpl, 1,            \
+        (unsigned) (lim) >> 16, 0, 0, 1, 0,                \
+        (unsigned) (base) >> 24                            \
+    }
+
+/* task state segment format (as described by the Pentium architecture book) */
+struct taskstate {
+    uint32_t ts_link;        // old ts selector
+    uintptr_t ts_esp0;        // stack pointers and segment selectors
+    uint16_t ts_ss0;        // after an increase in privilege level
+    uint16_t ts_padding1;
+    uintptr_t ts_esp1;
+    uint16_t ts_ss1;
+    uint16_t ts_padding2;
+    uintptr_t ts_esp2;
+    uint16_t ts_ss2;
+    uint16_t ts_padding3;
+    uintptr_t ts_cr3;        // page directory base
+    uintptr_t ts_eip;        // saved state from last task switch
+    uint32_t ts_eflags;
+    uint32_t ts_eax;        // more saved state (registers)
+    uint32_t ts_ecx;
+    uint32_t ts_edx;
+    uint32_t ts_ebx;
+    uintptr_t ts_esp;
+    uintptr_t ts_ebp;
+    uint32_t ts_esi;
+    uint32_t ts_edi;
+    uint16_t ts_es;            // even more saved state (segment selectors)
+    uint16_t ts_padding4;
+    uint16_t ts_cs;
+    uint16_t ts_padding5;
+    uint16_t ts_ss;
+    uint16_t ts_padding6;
+    uint16_t ts_ds;
+    uint16_t ts_padding7;
+    uint16_t ts_fs;
+    uint16_t ts_padding8;
+    uint16_t ts_gs;
+    uint16_t ts_padding9;
+    uint16_t ts_ldt;
+    uint16_t ts_padding10;
+    uint16_t ts_t;            // trap on task switch
+    uint16_t ts_iomb;        // i/o map base address
+};
+
+#endif /* !__KERN_MM_MMU_H__ */
+

labcodes_answer/lab1_result/kern/mm/pmm.c

@@ -0,0 +1,99 @@
+#include <defs.h>
+#include <x86.h>
+#include <mmu.h>
+#include <memlayout.h>
+#include <pmm.h>
+
+/* *
+ * Task State Segment:
+ *
+ * The TSS may reside anywhere in memory. A special segment register called
+ * the Task Register (TR) holds a segment selector that points a valid TSS
+ * segment descriptor which resides in the GDT. Therefore, to use a TSS
+ * the following must be done in function gdt_init:
+ *   - create a TSS descriptor entry in GDT
+ *   - add enough information to the TSS in memory as needed
+ *   - load the TR register with a segment selector for that segment
+ *
+ * There are several fileds in TSS for specifying the new stack pointer when a
+ * privilege level change happens. But only the fields SS0 and ESP0 are useful
+ * in our os kernel.
+ *
+ * The field SS0 contains the stack segment selector for CPL = 0, and the ESP0
+ * contains the new ESP value for CPL = 0. When an interrupt happens in protected
+ * mode, the x86 CPU will look in the TSS for SS0 and ESP0 and load their value
+ * into SS and ESP respectively.
+ * */
+static struct taskstate ts = {0};
+
+/* *
+ * Global Descriptor Table:
+ *
+ * The kernel and user segments are identical (except for the DPL). To load
+ * the %ss register, the CPL must equal the DPL. Thus, we must duplicate the
+ * segments for the user and the kernel. Defined as follows:
+ *   - 0x0 :  unused (always faults -- for trapping NULL far pointers)
+ *   - 0x8 :  kernel code segment
+ *   - 0x10:  kernel data segment
+ *   - 0x18:  user code segment
+ *   - 0x20:  user data segment
+ *   - 0x28:  defined for tss, initialized in gdt_init
+ * */
+static struct segdesc gdt[] = {
+    SEG_NULL,
+    [SEG_KTEXT] = SEG(STA_X | STA_R, 0x0, 0xFFFFFFFF, DPL_KERNEL),
+    [SEG_KDATA] = SEG(STA_W, 0x0, 0xFFFFFFFF, DPL_KERNEL),
+    [SEG_UTEXT] = SEG(STA_X | STA_R, 0x0, 0xFFFFFFFF, DPL_USER),
+    [SEG_UDATA] = SEG(STA_W, 0x0, 0xFFFFFFFF, DPL_USER),
+    [SEG_TSS]    = SEG_NULL,
+};
+
+static struct pseudodesc gdt_pd = {
+    sizeof(gdt) - 1, (uint32_t)gdt
+};
+
+/* *
+ * lgdt - load the global descriptor table register and reset the
+ * data/code segement registers for kernel.
+ * */
+static inline void
+lgdt(struct pseudodesc *pd) {
+    asm volatile ("lgdt (%0)" :: "r" (pd));
+    asm volatile ("movw %%ax, %%gs" :: "a" (USER_DS));
+    asm volatile ("movw %%ax, %%fs" :: "a" (USER_DS));
+    asm volatile ("movw %%ax, %%es" :: "a" (KERNEL_DS));
+    asm volatile ("movw %%ax, %%ds" :: "a" (KERNEL_DS));
+    asm volatile ("movw %%ax, %%ss" :: "a" (KERNEL_DS));
+    // reload cs
+    asm volatile ("ljmp %0, $1f\n 1:\n" :: "i" (KERNEL_CS));
+}
+
+/* temporary kernel stack */
+uint8_t stack0[1024];
+
+/* gdt_init - initialize the default GDT and TSS */
+static void
+gdt_init(void) {
+    // Setup a TSS so that we can get the right stack when we trap from
+    // user to the kernel. But not safe here, it's only a temporary value,
+    // it will be set to KSTACKTOP in lab2.
+    ts.ts_esp0 = (uint32_t)&stack0 + sizeof(stack0);
+    ts.ts_ss0 = KERNEL_DS;
+
+    // initialize the TSS filed of the gdt
+    gdt[SEG_TSS] = SEG16(STS_T32A, (uint32_t)&ts, sizeof(ts), DPL_KERNEL);
+    gdt[SEG_TSS].sd_s = 0;
+
+    // reload all segment registers
+    lgdt(&gdt_pd);
+
+    // load the TSS
+    ltr(GD_TSS);
+}
+
+/* pmm_init - initialize the physical memory management */
+void
+pmm_init(void) {
+    gdt_init();
+}
+

labcodes_answer/lab1_result/kern/mm/pmm.h

@@ -0,0 +1,7 @@
+#ifndef __KERN_MM_PMM_H__
+#define __KERN_MM_PMM_H__
+
+void pmm_init(void);
+
+#endif /* !__KERN_MM_PMM_H__ */
+

labcodes_answer/lab1_result/kern/trap/trap.c

@@ -0,0 +1,197 @@
+#include <defs.h>
+#include <mmu.h>
+#include <memlayout.h>
+#include <clock.h>
+#include <trap.h>
+#include <x86.h>
+#include <stdio.h>
+#include <assert.h>
+#include <console.h>
+#include <kdebug.h>
+
+#define TICK_NUM 100
+
+static void print_ticks() {
+    cprintf("%d ticks\n",TICK_NUM);
+#ifdef DEBUG_GRADE
+    cprintf("End of Test.\n");
+    panic("EOT: kernel seems ok.");
+#endif
+}
+
+/* *
+ * Interrupt descriptor table:
+ *
+ * Must be built at run time because shifted function addresses can't
+ * be represented in relocation records.
+ * */
+static struct gatedesc idt[256] = {{0}};
+
+static struct pseudodesc idt_pd = {
+    sizeof(idt) - 1, (uintptr_t)idt
+};
+
+/* idt_init - initialize IDT to each of the entry points in kern/trap/vectors.S */
+void
+idt_init(void) {
+     /* LAB1 YOUR CODE : STEP 2 */
+     /* (1) Where are the entry addrs of each Interrupt Service Routine (ISR)?
+      *     All ISR's entry addrs are stored in __vectors. where is uintptr_t __vectors[] ?
+      *     __vectors[] is in kern/trap/vector.S which is produced by tools/vector.c
+      *     (try "make" command in lab1, then you will find vector.S in kern/trap DIR)
+      *     You can use  "extern uintptr_t __vectors[];" to define this extern variable which will be used later.
+      * (2) Now you should setup the entries of ISR in Interrupt Description Table (IDT).
+      *     Can you see idt[256] in this file? Yes, it's IDT! you can use SETGATE macro to setup each item of IDT
+      * (3) After setup the contents of IDT, you will let CPU know where is the IDT by using 'lidt' instruction.
+      *     You don't know the meaning of this instruction? just google it! and check the libs/x86.h to know more.
+      *     Notice: the argument of lidt is idt_pd. try to find it!
+      */
+    extern uintptr_t __vectors[];
+    int i;
+    for (i = 0; i < sizeof(idt) / sizeof(struct gatedesc); i ++) {
+        SETGATE(idt[i], 0, GD_KTEXT, __vectors[i], DPL_KERNEL);
+    }
+    lidt(&idt_pd);
+}
+
+static const char *
+trapname(int trapno) {
+    static const char * const excnames[] = {
+        "Divide error",
+        "Debug",
+        "Non-Maskable Interrupt",
+        "Breakpoint",
+        "Overflow",
+        "BOUND Range Exceeded",
+        "Invalid Opcode",
+        "Device Not Available",
+        "Double Fault",
+        "Coprocessor Segment Overrun",
+        "Invalid TSS",
+        "Segment Not Present",
+        "Stack Fault",
+        "General Protection",
+        "Page Fault",
+        "(unknown trap)",
+        "x87 FPU Floating-Point Error",
+        "Alignment Check",
+        "Machine-Check",
+        "SIMD Floating-Point Exception"
+    };
+
+    if (trapno < sizeof(excnames)/sizeof(const char * const)) {
+        return excnames[trapno];
+    }
+    if (trapno >= IRQ_OFFSET && trapno < IRQ_OFFSET + 16) {
+        return "Hardware Interrupt";
+    }
+    return "(unknown trap)";
+}
+
+/* trap_in_kernel - test if trap happened in kernel */
+bool
+trap_in_kernel(struct trapframe *tf) {
+    return (tf->tf_cs == (uint16_t)KERNEL_CS);
+}
+
+static const char *IA32flags[] = {
+    "CF", NULL, "PF", NULL, "AF", NULL, "ZF", "SF",
+    "TF", "IF", "DF", "OF", NULL, NULL, "NT", NULL,
+    "RF", "VM", "AC", "VIF", "VIP", "ID", NULL, NULL,
+};
+
+void
+print_trapframe(struct trapframe *tf) {
+    cprintf("trapframe at %p\n", tf);
+    print_regs(&tf->tf_regs);
+    cprintf("  ds   0x----%04x\n", tf->tf_ds);
+    cprintf("  es   0x----%04x\n", tf->tf_es);
+    cprintf("  fs   0x----%04x\n", tf->tf_fs);
+    cprintf("  gs   0x----%04x\n", tf->tf_gs);
+    cprintf("  trap 0x%08x %s\n", tf->tf_trapno, trapname(tf->tf_trapno));
+    cprintf("  err  0x%08x\n", tf->tf_err);
+    cprintf("  eip  0x%08x\n", tf->tf_eip);
+    cprintf("  cs   0x----%04x\n", tf->tf_cs);
+    cprintf("  flag 0x%08x ", tf->tf_eflags);
+
+    int i, j;
+    for (i = 0, j = 1; i < sizeof(IA32flags) / sizeof(IA32flags[0]); i ++, j <<= 1) {
+        if ((tf->tf_eflags & j) && IA32flags[i] != NULL) {
+            cprintf("%s,", IA32flags[i]);
+        }
+    }
+    cprintf("IOPL=%d\n", (tf->tf_eflags & FL_IOPL_MASK) >> 12);
+
+    if (!trap_in_kernel(tf)) {
+        cprintf("  esp  0x%08x\n", tf->tf_esp);
+        cprintf("  ss   0x----%04x\n", tf->tf_ss);
+    }
+}
+
+void
+print_regs(struct pushregs *regs) {
+    cprintf("  edi  0x%08x\n", regs->reg_edi);
+    cprintf("  esi  0x%08x\n", regs->reg_esi);
+    cprintf("  ebp  0x%08x\n", regs->reg_ebp);
+    cprintf("  oesp 0x%08x\n", regs->reg_oesp);
+    cprintf("  ebx  0x%08x\n", regs->reg_ebx);
+    cprintf("  edx  0x%08x\n", regs->reg_edx);
+    cprintf("  ecx  0x%08x\n", regs->reg_ecx);
+    cprintf("  eax  0x%08x\n", regs->reg_eax);
+}
+
+/* trap_dispatch - dispatch based on what type of trap occurred */
+static void
+trap_dispatch(struct trapframe *tf) {
+    char c;
+
+    switch (tf->tf_trapno) {
+    case IRQ_OFFSET + IRQ_TIMER:
+        /* LAB1 YOUR CODE : STEP 3 */
+        /* handle the timer interrupt */
+        /* (1) After a timer interrupt, you should record this event using a global variable (increase it), such as ticks in kern/driver/clock.c
+         * (2) Every TICK_NUM cycle, you can print some info using a funciton, such as print_ticks().
+         * (3) Too Simple? Yes, I think so!
+         */
+        ticks ++;
+        if (ticks % TICK_NUM == 0) {
+            print_ticks();
+        }
+        break;
+    case IRQ_OFFSET + IRQ_COM1:
+        c = cons_getc();
+        cprintf("serial [%03d] %c\n", c, c);
+        break;
+    case IRQ_OFFSET + IRQ_KBD:
+        c = cons_getc();
+        cprintf("kbd [%03d] %c\n", c, c);
+        break;
+    //LAB1 CHALLENGE 1 : YOUR CODE you should modify below codes.
+    case T_SWITCH_TOU:
+    case T_SWITCH_TOK:
+        panic("T_SWITCH_** ??\n");
+        break;
+    case IRQ_OFFSET + IRQ_IDE1:
+    case IRQ_OFFSET + IRQ_IDE2:
+        /* do nothing */
+        break;
+    default:
+        // in kernel, it must be a mistake
+        if ((tf->tf_cs & 3) == 0) {
+            print_trapframe(tf);
+            panic("unexpected trap in kernel.\n");
+        }
+    }
+}
+
+/* *
+ * trap - handles or dispatches an exception/interrupt. if and when trap() returns,
+ * the code in kern/trap/trapentry.S restores the old CPU state saved in the
+ * trapframe and then uses the iret instruction to return from the exception.
+ * */
+void
+trap(struct trapframe *tf) {
+    // dispatch based on what type of trap occurred
+    trap_dispatch(tf);
+}
+

labcodes_answer/lab1_result/kern/trap/trap.h

@@ -0,0 +1,91 @@
+#ifndef __KERN_TRAP_TRAP_H__
+#define __KERN_TRAP_TRAP_H__
+
+#include <defs.h>
+
+/* Trap Numbers */
+
+/* Processor-defined: */
+#define T_DIVIDE                0    // divide error
+#define T_DEBUG                    1    // debug exception
+#define T_NMI                    2    // non-maskable interrupt
+#define T_BRKPT                    3    // breakpoint
+#define T_OFLOW                    4    // overflow
+#define T_BOUND                    5    // bounds check
+#define T_ILLOP                    6    // illegal opcode
+#define T_DEVICE                7    // device not available
+#define T_DBLFLT                8    // double fault
+// #define T_COPROC                9    // reserved (not used since 486)
+#define T_TSS                    10    // invalid task switch segment
+#define T_SEGNP                    11    // segment not present
+#define T_STACK                    12    // stack exception
+#define T_GPFLT                    13    // general protection fault
+#define T_PGFLT                    14    // page fault
+// #define T_RES                15    // reserved
+#define T_FPERR                    16    // floating point error
+#define T_ALIGN                    17    // aligment check
+#define T_MCHK                    18    // machine check
+#define T_SIMDERR                19    // SIMD floating point error
+
+#define T_SYSCALL               0x80 // SYSCALL, ONLY FOR THIS PROJ
+
+/* Hardware IRQ numbers. We receive these as (IRQ_OFFSET + IRQ_xx) */
+#define IRQ_OFFSET                32    // IRQ 0 corresponds to int IRQ_OFFSET
+
+#define IRQ_TIMER                0
+#define IRQ_KBD                    1
+#define IRQ_COM1                4
+#define IRQ_IDE1                14
+#define IRQ_IDE2                15
+#define IRQ_ERROR                19
+#define IRQ_SPURIOUS                31
+
+/* *
+ * These are arbitrarily chosen, but with care not to overlap
+ * processor defined exceptions or interrupt vectors.
+ * */
+#define T_SWITCH_TOU                120    // user/kernel switch
+#define T_SWITCH_TOK                121    // user/kernel switch
+
+/* registers as pushed by pushal */
+struct pushregs {
+    uint32_t reg_edi;
+    uint32_t reg_esi;
+    uint32_t reg_ebp;
+    uint32_t reg_oesp;            /* Useless */
+    uint32_t reg_ebx;
+    uint32_t reg_edx;
+    uint32_t reg_ecx;
+    uint32_t reg_eax;
+};
+
+struct trapframe {
+    struct pushregs tf_regs;
+    uint16_t tf_gs;
+    uint16_t tf_padding0;
+    uint16_t tf_fs;
+    uint16_t tf_padding1;
+    uint16_t tf_es;
+    uint16_t tf_padding2;
+    uint16_t tf_ds;
+    uint16_t tf_padding3;
+    uint32_t tf_trapno;
+    /* below here defined by x86 hardware */
+    uint32_t tf_err;
+    uintptr_t tf_eip;
+    uint16_t tf_cs;
+    uint16_t tf_padding4;
+    uint32_t tf_eflags;
+    /* below here only when crossing rings, such as from user to kernel */
+    uintptr_t tf_esp;
+    uint16_t tf_ss;
+    uint16_t tf_padding5;
+} __attribute__((packed));
+
+void idt_init(void);
+void print_trapframe(struct trapframe *tf);
+void print_regs(struct pushregs *regs);
+bool trap_in_kernel(struct trapframe *tf);
+
+#endif /* !__KERN_TRAP_TRAP_H__ */
+

labcodes_answer/lab1_result/kern/trap/trapentry.S

@@ -0,0 +1,44 @@
+#include <memlayout.h>
+
+# vectors.S sends all traps here.
+.text
+.globl __alltraps
+__alltraps:
+    # push registers to build a trap frame
+    # therefore make the stack look like a struct trapframe
+    pushl %ds
+    pushl %es
+    pushl %fs
+    pushl %gs
+    pushal
+
+    # load GD_KDATA into %ds and %es to set up data segments for kernel
+    movl $GD_KDATA, %eax
+    movw %ax, %ds
+    movw %ax, %es
+
+    # push %esp to pass a pointer to the trapframe as an argument to trap()
+    pushl %esp
+
+    # call trap(tf), where tf=%esp
+    call trap
+
+    # pop the pushed stack pointer
+    popl %esp
+
+    # return falls through to trapret...
+.globl __trapret
+__trapret:
+    # restore registers from stack
+    popal
+
+    # restore %ds, %es, %fs and %gs
+    popl %gs
+    popl %fs
+    popl %es
+    popl %ds
+
+    # get rid of the trap number and error code
+    addl $0x8, %esp
+    iret
+

labcodes_answer/lab1_result/libs/defs.h

@@ -0,0 +1,68 @@
+#ifndef __LIBS_DEFS_H__
+#define __LIBS_DEFS_H__
+
+#ifndef NULL
+#define NULL ((void *)0)
+#endif
+
+#define __always_inline inline __attribute__((always_inline))
+#define __noinline __attribute__((noinline))
+#define __noreturn __attribute__((noreturn))
+
+/* Represents true-or-false values */
+typedef int bool;
+
+/* Explicitly-sized versions of integer types */
+typedef char int8_t;
+typedef unsigned char uint8_t;
+typedef short int16_t;
+typedef unsigned short uint16_t;
+typedef int int32_t;
+typedef unsigned int uint32_t;
+typedef long long int64_t;
+typedef unsigned long long uint64_t;
+
+/* *
+ * Pointers and addresses are 32 bits long.
+ * We use pointer types to represent addresses,
+ * uintptr_t to represent the numerical values of addresses.
+ * */
+typedef int32_t intptr_t;
+typedef uint32_t uintptr_t;
+
+/* size_t is used for memory object sizes */
+typedef uintptr_t size_t;
+
+/* used for page numbers */
+typedef size_t ppn_t;
+
+/* *
+ * Rounding operations (efficient when n is a power of 2)
+ * Round down to the nearest multiple of n
+ * */
+#define ROUNDDOWN(a, n) ({                                          \
+            size_t __a = (size_t)(a);                               \
+            (typeof(a))(__a - __a % (n));                           \
+        })
+
+/* Round up to the nearest multiple of n */
+#define ROUNDUP(a, n) ({                                            \
+            size_t __n = (size_t)(n);                               \
+            (typeof(a))(ROUNDDOWN((size_t)(a) + __n - 1, __n));     \
+        })
+
+/* Return the offset of 'member' relative to the beginning of a struct type */
+#define offsetof(type, member)                                      \
+    ((size_t)(&((type *)0)->member))
+
+/* *
+ * to_struct - get the struct from a ptr
+ * @ptr:    a struct pointer of member
+ * @type:   the type of the struct this is embedded in
+ * @member: the name of the member within the struct
+ * */
+#define to_struct(ptr, type, member)                               \
+    ((type *)((char *)(ptr) - offsetof(type, member)))
+
+#endif /* !__LIBS_DEFS_H__ */
+

labcodes_answer/lab1_result/libs/elf.h

@@ -0,0 +1,40 @@
+#ifndef __LIBS_ELF_H__
+#define __LIBS_ELF_H__
+
+#include <defs.h>
+
+#define ELF_MAGIC    0x464C457FU            // "\x7FELF" in little endian
+
+/* file header */
+struct elfhdr {
+    uint32_t e_magic;     // must equal ELF_MAGIC
+    uint8_t e_elf[12];
+    uint16_t e_type;      // 1=relocatable, 2=executable, 3=shared object, 4=core image
+    uint16_t e_machine;   // 3=x86, 4=68K, etc.
+    uint32_t e_version;   // file version, always 1
+    uint32_t e_entry;     // entry point if executable
+    uint32_t e_phoff;     // file position of program header or 0
+    uint32_t e_shoff;     // file position of section header or 0
+    uint32_t e_flags;     // architecture-specific flags, usually 0
+    uint16_t e_ehsize;    // size of this elf header
+    uint16_t e_phentsize; // size of an entry in program header
+    uint16_t e_phnum;     // number of entries in program header or 0
+    uint16_t e_shentsize; // size of an entry in section header
+    uint16_t e_shnum;     // number of entries in section header or 0
+    uint16_t e_shstrndx;  // section number that contains section name strings
+};
+
+/* program section header */
+struct proghdr {
+    uint32_t p_type;   // loadable code or data, dynamic linking info,etc.
+    uint32_t p_offset; // file offset of segment
+    uint32_t p_va;     // virtual address to map segment
+    uint32_t p_pa;     // physical address, not used
+    uint32_t p_filesz; // size of segment in file
+    uint32_t p_memsz;  // size of segment in memory (bigger if contains bss）
+    uint32_t p_flags;  // read/write/execute bits
+    uint32_t p_align;  // required alignment, invariably hardware page size
+};
+
+#endif /* !__LIBS_ELF_H__ */
+

labcodes_answer/lab1_result/libs/error.h

@@ -0,0 +1,16 @@
+#ifndef __LIBS_ERROR_H__
+#define __LIBS_ERROR_H__
+
+/* kernel error codes -- keep in sync with list in lib/printfmt.c */
+#define E_UNSPECIFIED        1    // Unspecified or unknown problem
+#define E_BAD_PROC            2    // Process doesn't exist or otherwise
+#define E_INVAL                3    // Invalid parameter
+#define E_NO_MEM            4    // Request failed due to memory shortage
+#define E_NO_FREE_PROC        5    // Attempt to create a new process beyond
+#define E_FAULT                6    // Memory fault
+
+/* the maximum allowed */
+#define MAXERROR            6
+
+#endif /* !__LIBS_ERROR_H__ */
+

labcodes_answer/lab1_result/libs/printfmt.c

@@ -0,0 +1,340 @@
+#include <defs.h>
+#include <x86.h>
+#include <error.h>
+#include <stdio.h>
+#include <string.h>
+
+/* *
+ * Space or zero padding and a field width are supported for the numeric
+ * formats only.
+ *
+ * The special format %e takes an integer error code
+ * and prints a string describing the error.
+ * The integer may be positive or negative,
+ * so that -E_NO_MEM and E_NO_MEM are equivalent.
+ * */
+
+static const char * const error_string[MAXERROR + 1] = {
+    [0]                        NULL,
+    [E_UNSPECIFIED]            "unspecified error",
+    [E_BAD_PROC]            "bad process",
+    [E_INVAL]                "invalid parameter",
+    [E_NO_MEM]                "out of memory",
+    [E_NO_FREE_PROC]        "out of processes",
+    [E_FAULT]                "segmentation fault",
+};
+
+/* *
+ * printnum - print a number (base <= 16) in reverse order
+ * @putch:        specified putch function, print a single character
+ * @putdat:        used by @putch function
+ * @num:        the number will be printed
+ * @base:        base for print, must be in [1, 16]
+ * @width:         maximum number of digits, if the actual width is less than @width, use @padc instead
+ * @padc:        character that padded on the left if the actual width is less than @width
+ * */
+static void
+printnum(void (*putch)(int, void*), void *putdat,
+        unsigned long long num, unsigned base, int width, int padc) {
+    unsigned long long result = num;
+    unsigned mod = do_div(result, base);
+
+    // first recursively print all preceding (more significant) digits
+    if (num >= base) {
+        printnum(putch, putdat, result, base, width - 1, padc);
+    } else {
+        // print any needed pad characters before first digit
+        while (-- width > 0)
+            putch(padc, putdat);
+    }
+    // then print this (the least significant) digit
+    putch("0123456789abcdef"[mod], putdat);
+}
+
+/* *
+ * getuint - get an unsigned int of various possible sizes from a varargs list
+ * @ap:            a varargs list pointer
+ * @lflag:        determines the size of the vararg that @ap points to
+ * */
+static unsigned long long
+getuint(va_list *ap, int lflag) {
+    if (lflag >= 2) {
+        return va_arg(*ap, unsigned long long);
+    }
+    else if (lflag) {
+        return va_arg(*ap, unsigned long);
+    }
+    else {
+        return va_arg(*ap, unsigned int);
+    }
+}
+
+/* *
+ * getint - same as getuint but signed, we can't use getuint because of sign extension
+ * @ap:            a varargs list pointer
+ * @lflag:        determines the size of the vararg that @ap points to
+ * */
+static long long
+getint(va_list *ap, int lflag) {
+    if (lflag >= 2) {
+        return va_arg(*ap, long long);
+    }
+    else if (lflag) {
+        return va_arg(*ap, long);
+    }
+    else {
+        return va_arg(*ap, int);
+    }
+}
+
+/* *
+ * printfmt - format a string and print it by using putch
+ * @putch:        specified putch function, print a single character
+ * @putdat:        used by @putch function
+ * @fmt:        the format string to use
+ * */
+void
+printfmt(void (*putch)(int, void*), void *putdat, const char *fmt, ...) {
+    va_list ap;
+
+    va_start(ap, fmt);
+    vprintfmt(putch, putdat, fmt, ap);
+    va_end(ap);
+}
+
+/* *
+ * vprintfmt - format a string and print it by using putch, it's called with a va_list
+ * instead of a variable number of arguments
+ * @putch:        specified putch function, print a single character
+ * @putdat:        used by @putch function
+ * @fmt:        the format string to use
+ * @ap:            arguments for the format string
+ *
+ * Call this function if you are already dealing with a va_list.
+ * Or you probably want printfmt() instead.
+ * */
+void
+vprintfmt(void (*putch)(int, void*), void *putdat, const char *fmt, va_list ap) {
+    register const char *p;
+    register int ch, err;
+    unsigned long long num;
+    int base, width, precision, lflag, altflag;
+
+    while (1) {
+        while ((ch = *(unsigned char *)fmt ++) != '%') {
+            if (ch == '\0') {
+                return;
+            }
+            putch(ch, putdat);
+        }
+
+        // Process a %-escape sequence
+        char padc = ' ';
+        width = precision = -1;
+        lflag = altflag = 0;
+
+    reswitch:
+        switch (ch = *(unsigned char *)fmt ++) {
+
+        // flag to pad on the right
+        case '-':
+            padc = '-';
+            goto reswitch;
+
+        // flag to pad with 0's instead of spaces
+        case '0':
+            padc = '0';
+            goto reswitch;
+
+        // width field
+        case '1' ... '9':
+            for (precision = 0; ; ++ fmt) {
+                precision = precision * 10 + ch - '0';
+                ch = *fmt;
+                if (ch < '0' || ch > '9') {
+                    break;
+                }
+            }
+            goto process_precision;
+
+        case '*':
+            precision = va_arg(ap, int);
+            goto process_precision;
+
+        case '.':
+            if (width < 0)
+                width = 0;
+            goto reswitch;
+
+        case '#':
+            altflag = 1;
+            goto reswitch;
+
+        process_precision:
+            if (width < 0)
+                width = precision, precision = -1;
+            goto reswitch;
+
+        // long flag (doubled for long long)
+        case 'l':
+            lflag ++;
+            goto reswitch;
+
+        // character
+        case 'c':
+            putch(va_arg(ap, int), putdat);
+            break;
+
+        // error message
+        case 'e':
+            err = va_arg(ap, int);
+            if (err < 0) {
+                err = -err;
+            }
+            if (err > MAXERROR || (p = error_string[err]) == NULL) {
+                printfmt(putch, putdat, "error %d", err);
+            }
+            else {
+                printfmt(putch, putdat, "%s", p);
+            }
+            break;
+
+        // string
+        case 's':
+            if ((p = va_arg(ap, char *)) == NULL) {
+                p = "(null)";
+            }
+            if (width > 0 && padc != '-') {
+                for (width -= strnlen(p, precision); width > 0; width --) {
+                    putch(padc, putdat);
+                }
+            }
+            for (; (ch = *p ++) != '\0' && (precision < 0 || -- precision >= 0); width --) {
+                if (altflag && (ch < ' ' || ch > '~')) {
+                    putch('?', putdat);
+                }
+                else {
+                    putch(ch, putdat);
+                }
+            }
+            for (; width > 0; width --) {
+                putch(' ', putdat);
+            }
+            break;
+
+        // (signed) decimal
+        case 'd':
+            num = getint(&ap, lflag);
+            if ((long long)num < 0) {
+                putch('-', putdat);
+                num = -(long long)num;
+            }
+            base = 10;
+            goto number;
+
+        // unsigned decimal
+        case 'u':
+            num = getuint(&ap, lflag);
+            base = 10;
+            goto number;
+
+        // (unsigned) octal
+        case 'o':
+            num = getuint(&ap, lflag);
+            base = 8;
+            goto number;
+
+        // pointer
+        case 'p':
+            putch('0', putdat);
+            putch('x', putdat);
+            num = (unsigned long long)(uintptr_t)va_arg(ap, void *);
+            base = 16;
+            goto number;
+
+        // (unsigned) hexadecimal
+        case 'x':
+            num = getuint(&ap, lflag);
+            base = 16;
+        number:
+            printnum(putch, putdat, num, base, width, padc);
+            break;
+
+        // escaped '%' character
+        case '%':
+            putch(ch, putdat);
+            break;
+
+        // unrecognized escape sequence - just print it literally
+        default:
+            putch('%', putdat);
+            for (fmt --; fmt[-1] != '%'; fmt --)
+                /* do nothing */;
+            break;
+        }
+    }
+}
+
+/* sprintbuf is used to save enough information of a buffer */
+struct sprintbuf {
+    char *buf;            // address pointer points to the first unused memory
+    char *ebuf;            // points the end of the buffer
+    int cnt;            // the number of characters that have been placed in this buffer
+};
+
+/* *
+ * sprintputch - 'print' a single character in a buffer
+ * @ch:            the character will be printed
+ * @b:            the buffer to place the character @ch
+ * */
+static void
+sprintputch(int ch, struct sprintbuf *b) {
+    b->cnt ++;
+    if (b->buf < b->ebuf) {
+        *b->buf ++ = ch;
+    }
+}
+
+/* *
+ * snprintf - format a string and place it in a buffer
+ * @str:        the buffer to place the result into
+ * @size:        the size of buffer, including the trailing null space
+ * @fmt:        the format string to use
+ * */
+int
+snprintf(char *str, size_t size, const char *fmt, ...) {
+    va_list ap;
+    int cnt;
+    va_start(ap, fmt);
+    cnt = vsnprintf(str, size, fmt, ap);
+    va_end(ap);
+    return cnt;
+}
+
+/* *
+ * vsnprintf - format a string and place it in a buffer, it's called with a va_list
+ * instead of a variable number of arguments
+ * @str:        the buffer to place the result into
+ * @size:        the size of buffer, including the trailing null space
+ * @fmt:        the format string to use
+ * @ap:            arguments for the format string
+ *
+ * The return value is the number of characters which would be generated for the
+ * given input, excluding the trailing '\0'.
+ *
+ * Call this function if you are already dealing with a va_list.
+ * Or you probably want snprintf() instead.
+ * */
+int
+vsnprintf(char *str, size_t size, const char *fmt, va_list ap) {
+    struct sprintbuf b = {str, str + size - 1, 0};
+    if (str == NULL || b.buf > b.ebuf) {
+        return -E_INVAL;
+    }
+    // print the string to the buffer
+    vprintfmt((void*)sprintputch, &b, fmt, ap);
+    // null terminate the buffer
+    *b.buf = '\0';
+    return b.cnt;
+}
+

labcodes_answer/lab1_result/libs/stdarg.h

@@ -0,0 +1,12 @@
+#ifndef __LIBS_STDARG_H__
+#define __LIBS_STDARG_H__
+
+/* compiler provides size of save area */
+typedef __builtin_va_list va_list;
+
+#define va_start(ap, last)              (__builtin_va_start(ap, last))
+#define va_arg(ap, type)                (__builtin_va_arg(ap, type))
+#define va_end(ap)                      /*nothing*/
+
+#endif /* !__LIBS_STDARG_H__ */
+

labcodes_answer/lab1_result/libs/stdio.h

@@ -0,0 +1,24 @@
+#ifndef __LIBS_STDIO_H__
+#define __LIBS_STDIO_H__
+
+#include <defs.h>
+#include <stdarg.h>
+
+/* kern/libs/stdio.c */
+int cprintf(const char *fmt, ...);
+int vcprintf(const char *fmt, va_list ap);
+void cputchar(int c);
+int cputs(const char *str);
+int getchar(void);
+
+/* kern/libs/readline.c */
+char *readline(const char *prompt);
+
+/* libs/printfmt.c */
+void printfmt(void (*putch)(int, void *), void *putdat, const char *fmt, ...);
+void vprintfmt(void (*putch)(int, void *), void *putdat, const char *fmt, va_list ap);
+int snprintf(char *str, size_t size, const char *fmt, ...);
+int vsnprintf(char *str, size_t size, const char *fmt, va_list ap);
+
+#endif /* !__LIBS_STDIO_H__ */
+

labcodes_answer/lab1_result/libs/string.c

@@ -0,0 +1,367 @@
+#include <string.h>
+#include <x86.h>
+
+/* *
+ * strlen - calculate the length of the string @s, not including
+ * the terminating '\0' character.
+ * @s:        the input string
+ *
+ * The strlen() function returns the length of string @s.
+ * */
+size_t
+strlen(const char *s) {
+    size_t cnt = 0;
+    while (*s ++ != '\0') {
+        cnt ++;
+    }
+    return cnt;
+}
+
+/* *
+ * strnlen - calculate the length of the string @s, not including
+ * the terminating '\0' char acter, but at most @len.
+ * @s:        the input string
+ * @len:    the max-length that function will scan
+ *
+ * Note that, this function looks only at the first @len characters
+ * at @s, and never beyond @s + @len.
+ *
+ * The return value is strlen(s), if that is less than @len, or
+ * @len if there is no '\0' character among the first @len characters
+ * pointed by @s.
+ * */
+size_t
+strnlen(const char *s, size_t len) {
+    size_t cnt = 0;
+    while (cnt < len && *s ++ != '\0') {
+        cnt ++;
+    }
+    return cnt;
+}
+
+/* *
+ * strcpy - copies the string pointed by @src into the array pointed by @dst,
+ * including the terminating null character.
+ * @dst:    pointer to the destination array where the content is to be copied
+ * @src:    string to be copied
+ *
+ * The return value is @dst.
+ *
+ * To avoid overflows, the size of array pointed by @dst should be long enough to
+ * contain the same string as @src (including the terminating null character), and
+ * should not overlap in memory with @src.
+ * */
+char *
+strcpy(char *dst, const char *src) {
+#ifdef __HAVE_ARCH_STRCPY
+    return __strcpy(dst, src);
+#else
+    char *p = dst;
+    while ((*p ++ = *src ++) != '\0')
+        /* nothing */;
+    return dst;
+#endif /* __HAVE_ARCH_STRCPY */
+}
+
+/* *
+ * strncpy - copies the first @len characters of @src to @dst. If the end of string @src
+ * if found before @len characters have been copied, @dst is padded with '\0' until a
+ * total of @len characters have been written to it.
+ * @dst:    pointer to the destination array where the content is to be copied
+ * @src:    string to be copied
+ * @len:    maximum number of characters to be copied from @src
+ *
+ * The return value is @dst
+ * */
+char *
+strncpy(char *dst, const char *src, size_t len) {
+    char *p = dst;
+    while (len > 0) {
+        if ((*p = *src) != '\0') {
+            src ++;
+        }
+        p ++, len --;
+    }
+    return dst;
+}
+
+/* *
+ * strcmp - compares the string @s1 and @s2
+ * @s1:        string to be compared
+ * @s2:        string to be compared
+ *
+ * This function starts comparing the first character of each string. If
+ * they are equal to each other, it continues with the following pairs until
+ * the characters differ or until a terminanting null-character is reached.
+ *
+ * Returns an integral value indicating the relationship between the strings:
+ * - A zero value indicates that both strings are equal;
+ * - A value greater than zero indicates that the first character that does
+ *   not match has a greater value in @s1 than in @s2;
+ * - And a value less than zero indicates the opposite.
+ * */
+int
+strcmp(const char *s1, const char *s2) {
+#ifdef __HAVE_ARCH_STRCMP
+    return __strcmp(s1, s2);
+#else
+    while (*s1 != '\0' && *s1 == *s2) {
+        s1 ++, s2 ++;
+    }
+    return (int)((unsigned char)*s1 - (unsigned char)*s2);
+#endif /* __HAVE_ARCH_STRCMP */
+}
+
+/* *
+ * strncmp - compares up to @n characters of the string @s1 to those of the string @s2
+ * @s1:        string to be compared
+ * @s2:        string to be compared
+ * @n:        maximum number of characters to compare
+ *
+ * This function starts comparing the first character of each string. If
+ * they are equal to each other, it continues with the following pairs until
+ * the characters differ, until a terminating null-character is reached, or
+ * until @n characters match in both strings, whichever happens first.
+ * */
+int
+strncmp(const char *s1, const char *s2, size_t n) {
+    while (n > 0 && *s1 != '\0' && *s1 == *s2) {
+        n --, s1 ++, s2 ++;
+    }
+    return (n == 0) ? 0 : (int)((unsigned char)*s1 - (unsigned char)*s2);
+}
+
+/* *
+ * strchr - locates first occurrence of character in string
+ * @s:        the input string
+ * @c:        character to be located
+ *
+ * The strchr() function returns a pointer to the first occurrence of
+ * character in @s. If the value is not found, the function returns 'NULL'.
+ * */
+char *
+strchr(const char *s, char c) {
+    while (*s != '\0') {
+        if (*s == c) {
+            return (char *)s;
+        }
+        s ++;
+    }
+    return NULL;
+}
+
+/* *
+ * strfind - locates first occurrence of character in string
+ * @s:        the input string
+ * @c:        character to be located
+ *
+ * The strfind() function is like strchr() except that if @c is
+ * not found in @s, then it returns a pointer to the null byte at the
+ * end of @s, rather than 'NULL'.
+ * */
+char *
+strfind(const char *s, char c) {
+    while (*s != '\0') {
+        if (*s == c) {
+            break;
+        }
+        s ++;
+    }
+    return (char *)s;
+}
+
+/* *
+ * strtol - converts string to long integer
+ * @s:        the input string that contains the representation of an integer number
+ * @endptr:    reference to an object of type char *, whose value is set by the
+ *             function to the next character in @s after the numerical value. This
+ *             parameter can also be a null pointer, in which case it is not used.
+ * @base:    x
+ *
+ * The function first discards as many whitespace characters as necessary until
+ * the first non-whitespace character is found. Then, starting from this character,
+ * takes as many characters as possible that are valid following a syntax that
+ * depends on the base parameter, and interprets them as a numerical value. Finally,
+ * a pointer to the first character following the integer representation in @s
+ * is stored in the object pointed by @endptr.
+ *
+ * If the value of base is zero, the syntax expected is similar to that of
+ * integer constants, which is formed by a succession of:
+ * - An optional plus or minus sign;
+ * - An optional prefix indicating octal or hexadecimal base ("0" or "0x" respectively)
+ * - A sequence of decimal digits (if no base prefix was specified) or either octal
+ *   or hexadecimal digits if a specific prefix is present
+ *
+ * If the base value is between 2 and 36, the format expected for the integral number
+ * is a succession of the valid digits and/or letters needed to represent integers of
+ * the specified radix (starting from '0' and up to 'z'/'Z' for radix 36). The
+ * sequence may optionally be preceded by a plus or minus sign and, if base is 16,
+ * an optional "0x" or "0X" prefix.
+ *
+ * The strtol() function returns the converted integral number as a long int value.
+ * */
+long
+strtol(const char *s, char **endptr, int base) {
+    int neg = 0;
+    long val = 0;
+
+    // gobble initial whitespace
+    while (*s == ' ' || *s == '\t') {
+        s ++;
+    }
+
+    // plus/minus sign
+    if (*s == '+') {
+        s ++;
+    }
+    else if (*s == '-') {
+        s ++, neg = 1;
+    }
+
+    // hex or octal base prefix
+    if ((base == 0 || base == 16) && (s[0] == '0' && s[1] == 'x')) {
+        s += 2, base = 16;
+    }
+    else if (base == 0 && s[0] == '0') {
+        s ++, base = 8;
+    }
+    else if (base == 0) {
+        base = 10;
+    }
+
+    // digits
+    while (1) {
+        int dig;
+
+        if (*s >= '0' && *s <= '9') {
+            dig = *s - '0';
+        }
+        else if (*s >= 'a' && *s <= 'z') {
+            dig = *s - 'a' + 10;
+        }
+        else if (*s >= 'A' && *s <= 'Z') {
+            dig = *s - 'A' + 10;
+        }
+        else {
+            break;
+        }
+        if (dig >= base) {
+            break;
+        }
+        s ++, val = (val * base) + dig;
+        // we don't properly detect overflow!
+    }
+
+    if (endptr) {
+        *endptr = (char *) s;
+    }
+    return (neg ? -val : val);
+}
+
+/* *
+ * memset - sets the first @n bytes of the memory area pointed by @s
+ * to the specified value @c.
+ * @s:        pointer the the memory area to fill
+ * @c:        value to set
+ * @n:        number of bytes to be set to the value
+ *
+ * The memset() function returns @s.
+ * */
+void *
+memset(void *s, char c, size_t n) {
+#ifdef __HAVE_ARCH_MEMSET
+    return __memset(s, c, n);
+#else
+    char *p = s;
+    while (n -- > 0) {
+        *p ++ = c;
+    }
+    return s;
+#endif /* __HAVE_ARCH_MEMSET */
+}
+
+/* *
+ * memmove - copies the values of @n bytes from the location pointed by @src to
+ * the memory area pointed by @dst. @src and @dst are allowed to overlap.
+ * @dst        pointer to the destination array where the content is to be copied
+ * @src        pointer to the source of data to by copied
+ * @n:        number of bytes to copy
+ *
+ * The memmove() function returns @dst.
+ * */
+void *
+memmove(void *dst, const void *src, size_t n) {
+#ifdef __HAVE_ARCH_MEMMOVE
+    return __memmove(dst, src, n);
+#else
+    const char *s = src;
+    char *d = dst;
+    if (s < d && s + n > d) {
+        s += n, d += n;
+        while (n -- > 0) {
+            *-- d = *-- s;
+        }
+    } else {
+        while (n -- > 0) {
+            *d ++ = *s ++;
+        }
+    }
+    return dst;
+#endif /* __HAVE_ARCH_MEMMOVE */
+}
+
+/* *
+ * memcpy - copies the value of @n bytes from the location pointed by @src to
+ * the memory area pointed by @dst.
+ * @dst        pointer to the destination array where the content is to be copied
+ * @src        pointer to the source of data to by copied
+ * @n:        number of bytes to copy
+ *
+ * The memcpy() returns @dst.
+ *
+ * Note that, the function does not check any terminating null character in @src,
+ * it always copies exactly @n bytes. To avoid overflows, the size of arrays pointed
+ * by both @src and @dst, should be at least @n bytes, and should not overlap
+ * (for overlapping memory area, memmove is a safer approach).
+ * */
+void *
+memcpy(void *dst, const void *src, size_t n) {
+#ifdef __HAVE_ARCH_MEMCPY
+    return __memcpy(dst, src, n);
+#else
+    const char *s = src;
+    char *d = dst;
+    while (n -- > 0) {
+        *d ++ = *s ++;
+    }
+    return dst;
+#endif /* __HAVE_ARCH_MEMCPY */
+}
+
+/* *
+ * memcmp - compares two blocks of memory
+ * @v1:        pointer to block of memory
+ * @v2:        pointer to block of memory
+ * @n:        number of bytes to compare
+ *
+ * The memcmp() functions returns an integral value indicating the
+ * relationship between the content of the memory blocks:
+ * - A zero value indicates that the contents of both memory blocks are equal;
+ * - A value greater than zero indicates that the first byte that does not
+ *   match in both memory blocks has a greater value in @v1 than in @v2
+ *   as if evaluated as unsigned char values;
+ * - And a value less than zero indicates the opposite.
+ * */
+int
+memcmp(const void *v1, const void *v2, size_t n) {
+    const char *s1 = (const char *)v1;
+    const char *s2 = (const char *)v2;
+    while (n -- > 0) {
+        if (*s1 != *s2) {
+            return (int)((unsigned char)*s1 - (unsigned char)*s2);
+        }
+        s1 ++, s2 ++;
+    }
+    return 0;
+}
+

labcodes_answer/lab1_result/libs/string.h

@@ -0,0 +1,25 @@
+#ifndef __LIBS_STRING_H__
+#define __LIBS_STRING_H__
+
+#include <defs.h>
+
+size_t strlen(const char *s);
+size_t strnlen(const char *s, size_t len);
+
+char *strcpy(char *dst, const char *src);
+char *strncpy(char *dst, const char *src, size_t len);
+
+int strcmp(const char *s1, const char *s2);
+int strncmp(const char *s1, const char *s2, size_t n);
+
+char *strchr(const char *s, char c);
+char *strfind(const char *s, char c);
+long strtol(const char *s, char **endptr, int base);
+
+void *memset(void *s, char c, size_t n);
+void *memmove(void *dst, const void *src, size_t n);
+void *memcpy(void *dst, const void *src, size_t n);
+int memcmp(const void *v1, const void *v2, size_t n);
+
+#endif /* !__LIBS_STRING_H__ */
+

labcodes_answer/lab1_result/libs/x86.h

@@ -0,0 +1,191 @@
+#ifndef __LIBS_X86_H__
+#define __LIBS_X86_H__
+
+#include <defs.h>
+
+#define do_div(n, base) ({                                        \
+    unsigned long __upper, __low, __high, __mod, __base;        \
+    __base = (base);                                            \
+    asm("" : "=a" (__low), "=d" (__high) : "A" (n));            \
+    __upper = __high;                                            \
+    if (__high != 0) {                                            \
+        __upper = __high % __base;                                \
+        __high = __high / __base;                                \
+    }                                                            \
+    asm("divl %2" : "=a" (__low), "=d" (__mod)                    \
+        : "rm" (__base), "0" (__low), "1" (__upper));            \
+    asm("" : "=A" (n) : "a" (__low), "d" (__high));                \
+    __mod;                                                        \
+ })
+
+static inline uint8_t inb(uint16_t port) __attribute__((always_inline));
+static inline void insl(uint32_t port, void *addr, int cnt) __attribute__((always_inline));
+static inline void outb(uint16_t port, uint8_t data) __attribute__((always_inline));
+static inline void outw(uint16_t port, uint16_t data) __attribute__((always_inline));
+static inline uint32_t read_ebp(void) __attribute__((always_inline));
+
+/* Pseudo-descriptors used for LGDT, LLDT(not used) and LIDT instructions. */
+struct pseudodesc {
+    uint16_t pd_lim;        // Limit
+    uint32_t pd_base;        // Base address
+} __attribute__ ((packed));
+
+static inline void lidt(struct pseudodesc *pd) __attribute__((always_inline));
+static inline void sti(void) __attribute__((always_inline));
+static inline void cli(void) __attribute__((always_inline));
+static inline void ltr(uint16_t sel) __attribute__((always_inline));
+
+static inline uint8_t
+inb(uint16_t port) {
+    uint8_t data;
+    asm volatile ("inb %1, %0" : "=a" (data) : "d" (port));
+    return data;
+}
+
+static inline void
+insl(uint32_t port, void *addr, int cnt) {
+    asm volatile (
+            "cld;"
+            "repne; insl;"
+            : "=D" (addr), "=c" (cnt)
+            : "d" (port), "0" (addr), "1" (cnt)
+            : "memory", "cc");
+}
+
+static inline void
+outb(uint16_t port, uint8_t data) {
+    asm volatile ("outb %0, %1" :: "a" (data), "d" (port));
+}
+
+static inline void
+outw(uint16_t port, uint16_t data) {
+    asm volatile ("outw %0, %1" :: "a" (data), "d" (port));
+}
+
+static inline uint32_t
+read_ebp(void) {
+    uint32_t ebp;
+    asm volatile ("movl %%ebp, %0" : "=r" (ebp));
+    return ebp;
+}
+
+static inline void
+lidt(struct pseudodesc *pd) {
+    asm volatile ("lidt (%0)" :: "r" (pd));
+}
+
+static inline void
+sti(void) {
+    asm volatile ("sti");
+}
+
+static inline void
+cli(void) {
+    asm volatile ("cli");
+}
+
+static inline void
+ltr(uint16_t sel) {
+    asm volatile ("ltr %0" :: "r" (sel));
+}
+
+static inline int __strcmp(const char *s1, const char *s2) __attribute__((always_inline));
+static inline char *__strcpy(char *dst, const char *src) __attribute__((always_inline));
+static inline void *__memset(void *s, char c, size_t n) __attribute__((always_inline));
+static inline void *__memmove(void *dst, const void *src, size_t n) __attribute__((always_inline));
+static inline void *__memcpy(void *dst, const void *src, size_t n) __attribute__((always_inline));
+
+#ifndef __HAVE_ARCH_STRCMP
+#define __HAVE_ARCH_STRCMP
+static inline int
+__strcmp(const char *s1, const char *s2) {
+    int d0, d1, ret;
+    asm volatile (
+            "1: lodsb;"
+            "scasb;"
+            "jne 2f;"
+            "testb %%al, %%al;"
+            "jne 1b;"
+            "xorl %%eax, %%eax;"
+            "jmp 3f;"
+            "2: sbbl %%eax, %%eax;"
+            "orb $1, %%al;"
+            "3:"
+            : "=a" (ret), "=&S" (d0), "=&D" (d1)
+            : "1" (s1), "2" (s2)
+            : "memory");
+    return ret;
+}
+
+#endif /* __HAVE_ARCH_STRCMP */
+
+#ifndef __HAVE_ARCH_STRCPY
+#define __HAVE_ARCH_STRCPY
+static inline char *
+__strcpy(char *dst, const char *src) {
+    int d0, d1, d2;
+    asm volatile (
+            "1: lodsb;"
+            "stosb;"
+            "testb %%al, %%al;"
+            "jne 1b;"
+            : "=&S" (d0), "=&D" (d1), "=&a" (d2)
+            : "0" (src), "1" (dst) : "memory");
+    return dst;
+}
+#endif /* __HAVE_ARCH_STRCPY */
+
+#ifndef __HAVE_ARCH_MEMSET
+#define __HAVE_ARCH_MEMSET
+static inline void *
+__memset(void *s, char c, size_t n) {
+    int d0, d1;
+    asm volatile (
+            "rep; stosb;"
+            : "=&c" (d0), "=&D" (d1)
+            : "0" (n), "a" (c), "1" (s)
+            : "memory");
+    return s;
+}
+#endif /* __HAVE_ARCH_MEMSET */
+
+#ifndef __HAVE_ARCH_MEMMOVE
+#define __HAVE_ARCH_MEMMOVE
+static inline void *
+__memmove(void *dst, const void *src, size_t n) {
+    if (dst < src) {
+        return __memcpy(dst, src, n);
+    }
+    int d0, d1, d2;
+    asm volatile (
+            "std;"
+            "rep; movsb;"
+            "cld;"
+            : "=&c" (d0), "=&S" (d1), "=&D" (d2)
+            : "0" (n), "1" (n - 1 + src), "2" (n - 1 + dst)
+            : "memory");
+    return dst;
+}
+#endif /* __HAVE_ARCH_MEMMOVE */
+
+#ifndef __HAVE_ARCH_MEMCPY
+#define __HAVE_ARCH_MEMCPY
+static inline void *
+__memcpy(void *dst, const void *src, size_t n) {
+    int d0, d1, d2;
+    asm volatile (
+            "rep; movsl;"
+            "movl %4, %%ecx;"
+            "andl $3, %%ecx;"
+            "jz 1f;"
+            "rep; movsb;"
+            "1:"
+            : "=&c" (d0), "=&D" (d1), "=&S" (d2)
+            : "0" (n / 4), "g" (n), "1" (dst), "2" (src)
+            : "memory");
+    return dst;
+}
+#endif /* __HAVE_ARCH_MEMCPY */
+
+#endif /* !__LIBS_X86_H__ */
+

labcodes_answer/lab1_result/tools/function.mk

@@ -0,0 +1,95 @@
+OBJPREFIX	:= __objs_
+
+.SECONDEXPANSION:
+# -------------------- function begin --------------------
+
+# list all files in some directories: (#directories, #types)
+listf = $(filter $(if $(2),$(addprefix %.,$(2)),%),\
+		  $(wildcard $(addsuffix $(SLASH)*,$(1))))
+
+# get .o obj files: (#files[, packet])
+toobj = $(addprefix $(OBJDIR)$(SLASH)$(if $(2),$(2)$(SLASH)),\
+		$(addsuffix .o,$(basename $(1))))
+
+# get .d dependency files: (#files[, packet])
+todep = $(patsubst %.o,%.d,$(call toobj,$(1),$(2)))
+
+totarget = $(addprefix $(BINDIR)$(SLASH),$(1))
+
+# change $(name) to $(OBJPREFIX)$(name): (#names)
+packetname = $(if $(1),$(addprefix $(OBJPREFIX),$(1)),$(OBJPREFIX))
+
+# cc compile template, generate rule for dep, obj: (file, cc[, flags, dir])
+define cc_template
+$$(call todep,$(1),$(4)): $(1) | $$$$(dir $$$$@)
+	@$(2) -I$$(dir $(1)) $(3) -MM $$< -MT "$$(patsubst %.d,%.o,$$@) $$@"> $$@
+$$(call toobj,$(1),$(4)): $(1) | $$$$(dir $$$$@)
+	@echo + cc $$<
+	$(V)$(2) -I$$(dir $(1)) $(3) -c $$< -o $$@
+ALLOBJS += $$(call toobj,$(1),$(4))
+endef
+
+# compile file: (#files, cc[, flags, dir])
+define do_cc_compile
+$$(foreach f,$(1),$$(eval $$(call cc_template,$$(f),$(2),$(3),$(4))))
+endef
+
+# add files to packet: (#files, cc[, flags, packet, dir])
+define do_add_files_to_packet
+__temp_packet__ := $(call packetname,$(4))
+ifeq ($$(origin $$(__temp_packet__)),undefined)
+$$(__temp_packet__) :=
+endif
+__temp_objs__ := $(call toobj,$(1),$(5))
+$$(foreach f,$(1),$$(eval $$(call cc_template,$$(f),$(2),$(3),$(5))))
+$$(__temp_packet__) += $$(__temp_objs__)
+endef
+
+# add objs to packet: (#objs, packet)
+define do_add_objs_to_packet
+__temp_packet__ := $(call packetname,$(2))
+ifeq ($$(origin $$(__temp_packet__)),undefined)
+$$(__temp_packet__) :=
+endif
+$$(__temp_packet__) += $(1)
+endef
+
+# add packets and objs to target (target, #packes, #objs[, cc, flags])
+define do_create_target
+__temp_target__ = $(call totarget,$(1))
+__temp_objs__ = $$(foreach p,$(call packetname,$(2)),$$($$(p))) $(3)
+TARGETS += $$(__temp_target__)
+ifneq ($(4),)
+$$(__temp_target__): $$(__temp_objs__) | $$$$(dir $$$$@)
+	$(V)$(4) $(5) $$^ -o $$@
+else
+$$(__temp_target__): $$(__temp_objs__) | $$$$(dir $$$$@)
+endif
+endef
+
+# finish all
+define do_finish_all
+ALLDEPS = $$(ALLOBJS:.o=.d)
+$$(sort $$(dir $$(ALLOBJS)) $(BINDIR) $(OBJDIR)):
+	@$(MKDIR) $$@
+endef
+
+# --------------------  function end  --------------------
+# compile file: (#files, cc[, flags, dir])
+cc_compile = $(eval $(call do_cc_compile,$(1),$(2),$(3),$(4)))
+
+# add files to packet: (#files, cc[, flags, packet, dir])
+add_files = $(eval $(call do_add_files_to_packet,$(1),$(2),$(3),$(4),$(5)))
+
+# add objs to packet: (#objs, packet)
+add_objs = $(eval $(call do_add_objs_to_packet,$(1),$(2)))
+
+# add packets and objs to target (target, #packes, #objs, cc, [, flags])
+create_target = $(eval $(call do_create_target,$(1),$(2),$(3),$(4),$(5)))
+
+read_packet = $(foreach p,$(call packetname,$(1)),$($(p)))
+
+add_dependency = $(eval $(1): $(2))
+
+finish_all = $(eval $(call do_finish_all))
+

labcodes_answer/lab1_result/tools/gdbinit

@@ -0,0 +1,4 @@
+file bin/kernel
+target remote :1234
+break kern_init
+continue

labcodes_answer/lab1_result/tools/grade.sh

@@ -0,0 +1,348 @@
+#!/bin/sh
+
+verbose=false
+if [ "x$1" = "x-v" ]; then
+	verbose=true
+	out=/dev/stdout
+	err=/dev/stderr
+else
+	out=/dev/null
+	err=/dev/null
+fi
+
+## make & makeopts
+if gmake --version > /dev/null 2>&1; then
+	make=gmake;
+else
+	make=make;
+fi
+
+makeopts="--quiet --no-print-directory -j"
+
+make_print() {
+	echo `$make $makeopts print-$1`
+}
+
+## command tools
+awk='awk'
+bc='bc'
+date='date'
+grep='grep'
+rm='rm -f'
+sed='sed'
+
+## symbol table
+sym_table='obj/kernel.sym'
+
+## gdb & gdbopts
+gdb="$(make_print GCCPREFIX)gdb"
+gdbport='1234'
+
+gdb_in="$(make_print GRADE_GDB_IN)"
+
+## qemu & qemuopts
+qemu="$(make_print qemu)"
+
+qemu_out="$(make_print GRADE_QEMU_OUT)"
+
+if $qemu -nographic -help | grep -q '^-gdb'; then
+	qemugdb="-gdb tcp::$gdbport"
+else
+	qemugdb="-s -p $gdbport"
+fi
+
+## default variables
+default_timeout=30
+default_pts=5
+
+pts=5
+part=0
+part_pos=0
+total=0
+total_pos=0
+
+## default functions
+update_score() {
+	total=`expr $total + $part`
+	total_pos=`expr $total_pos + $part_pos`
+	part=0
+	part_pos=0
+}
+
+get_time() {
+	echo `$date +%s.%N 2> /dev/null`
+}
+
+show_part() {
+	echo "Part $1 Score: $part/$part_pos"
+	echo
+	update_score
+}
+
+show_final() {
+	update_score
+	echo "Total Score: $total/$total_pos"
+	if [ $total -lt $total_pos ]; then
+		exit 1
+	fi
+}
+
+show_time() {
+	t1=$(get_time)
+	time=`echo "scale=1; ($t1-$t0)/1" | $sed 's/.N/.0/g' | $bc 2> /dev/null`
+	echo "(${time}s)"
+}
+
+show_build_tag() {
+	echo "$1:" | $awk '{printf "%-24s ", $0}'
+}
+
+show_check_tag() {
+	echo "$1:" | $awk '{printf "  -%-40s  ", $0}'
+}
+
+show_msg() {
+	echo $1
+	shift
+	if [ $# -gt 0 ]; then
+		echo "$@" | awk '{printf "   %s\n", $0}'
+		echo
+	fi
+}
+
+pass() {
+	show_msg OK "$@"
+	part=`expr $part + $pts`
+	part_pos=`expr $part_pos + $pts`
+}
+
+fail() {
+	show_msg WRONG "$@"
+	part_pos=`expr $part_pos + $pts`
+}
+
+run_qemu() {
+	# Run qemu with serial output redirected to $qemu_out. If $brkfun is non-empty,
+	# wait until $brkfun is reached or $timeout expires, then kill QEMU
+	qemuextra=
+	if [ "$brkfun" ]; then
+		qemuextra="-S $qemugdb"
+	fi
+
+	if [ -z "$timeout" ] || [ $timeout -le 0 ]; then
+		timeout=$default_timeout;
+	fi
+
+	t0=$(get_time)
+	(
+		ulimit -t $timeout
+		exec $qemu -nographic $qemuopts -serial file:$qemu_out -monitor null -no-reboot $qemuextra
+	) > $out 2> $err &
+	pid=$!
+
+	# wait for QEMU to start
+	sleep 1
+
+	if [ -n "$brkfun" ]; then
+		# find the address of the kernel $brkfun function
+		brkaddr=`$grep " $brkfun\$" $sym_table | $sed -e's/ .*$//g'`
+		(
+			echo "target remote localhost:$gdbport"
+			echo "break *0x$brkaddr"
+			echo "continue"
+		) > $gdb_in
+
+		$gdb -batch -nx -x $gdb_in > /dev/null 2>&1
+
+		# make sure that QEMU is dead
+		# on OS X, exiting gdb doesn't always exit qemu
+		kill $pid > /dev/null 2>&1
+	fi
+}
+
+build_run() {
+	# usage: build_run <tag> <args>
+	show_build_tag "$1"
+	shift
+
+	if $verbose; then
+		echo "$make $@ ..."
+	fi
+	$make $makeopts $@ 'DEFS+=-DDEBUG_GRADE' > $out 2> $err
+
+	if [ $? -ne 0 ]; then
+		echo $make $@ failed
+		exit 1
+	fi
+
+	# now run qemu and save the output
+	run_qemu
+
+	show_time
+}
+
+check_result() {
+	# usage: check_result <tag> <check> <check args...>
+	show_check_tag "$1"
+	shift
+
+	# give qemu some time to run (for asynchronous mode)
+	if [ ! -s $qemu_out ]; then
+		sleep 4
+	fi
+
+	if [ ! -s $qemu_out ]; then
+		fail > /dev/null
+		echo 'no $qemu_out'
+	else
+		check=$1
+		shift
+		$check "$@"
+	fi
+}
+
+check_regexps() {
+	okay=yes
+	not=0
+	reg=0
+	error=
+	for i do
+		if [ "x$i" = "x!" ]; then
+			not=1
+		elif [ "x$i" = "x-" ]; then
+			reg=1
+		else
+			if [ $reg -ne 0 ]; then
+				$grep '-E' "^$i\$" $qemu_out > /dev/null
+			else
+				$grep '-F' "$i" $qemu_out > /dev/null
+			fi
+			found=$(($? == 0))
+			if [ $found -eq $not ]; then
+				if [ $found -eq 0 ]; then
+					msg="!! error: missing '$i'"
+				else
+					msg="!! error: got unexpected line '$i'"
+				fi
+				okay=no
+				if [ -z "$error" ]; then
+					error="$msg"
+				else
+					error="$error\n$msg"
+				fi
+			fi
+			not=0
+			reg=0
+		fi
+	done
+	if [ "$okay" = "yes" ]; then
+		pass
+	else
+		fail "$error"
+		if $verbose; then
+			exit 1
+		fi
+	fi
+}
+
+run_test() {
+	# usage: run_test [-tag <tag>] [-Ddef...] [-check <check>] checkargs ...
+	tag=
+	check=check_regexps
+	while true; do
+		select=
+		case $1 in
+			-tag)
+				select=`expr substr $1 2 ${#1}`
+				eval $select='$2'
+				;;
+		esac
+		if [ -z "$select" ]; then
+			break
+		fi
+		shift
+		shift
+	done
+	defs=
+	while expr "x$1" : "x-D.*" > /dev/null; do
+		defs="DEFS+='$1' $defs"
+		shift
+	done
+	if [ "x$1" = "x-check" ]; then
+		check=$2
+		shift
+		shift
+	fi
+
+	$make $makeopts touch > /dev/null 2>&1
+	build_run "$tag" "$defs"
+
+	check_result 'check result' "$check" "$@"
+}
+
+quick_run() {
+	# usage: quick_run <tag> [-Ddef...]
+	tag="$1"
+	shift
+	defs=
+	while expr "x$1" : "x-D.*" > /dev/null; do
+		defs="DEFS+='$1' $defs"
+		shift
+	done
+
+	$make $makeopts touch > /dev/null 2>&1
+	build_run "$tag" "$defs"
+}
+
+quick_check() {
+	# usage: quick_check <tag> checkargs ...
+	tag="$1"
+	shift
+	check_result "$tag" check_regexps "$@"
+}
+
+## kernel image
+osimg=$(make_print ucoreimg)
+
+## set default qemu-options
+qemuopts="-hda $osimg"
+
+## set break-function, default is readline
+brkfun=readline
+
+## check now!!
+
+quick_run 'Check Output'
+
+pts=10
+quick_check 'check ring 0'										\
+	'0: @ring 0'												\
+	'0:  cs = 8'												\
+	'0:  ds = 10'												\
+	'0:  es = 10'												\
+	'0:  ss = 10'
+
+quick_check 'check switch to ring 3'							\
+	'+++ switch to  user  mode +++'								\
+	'1: @ring 3'												\
+	'1:  cs = 1b'												\
+	'1:  ds = 23'												\
+	'1:  es = 23'												\
+	'1:  ss = 23'
+
+quick_check 'check switch to ring 0'							\
+	'+++ switch to kernel mode +++'								\
+	'2: @ring 0'												\
+	'2:  cs = 8'												\
+	'2:  ds = 10'												\
+	'2:  es = 10'												\
+	'2:  ss = 10'
+
+quick_check 'check ticks'										\
+	'++ setup timer interrupts'									\
+	'100 ticks'													\
+	'End of Test.'
+
+## print final-score
+show_final
+

labcodes_answer/lab1_result/tools/kernel.ld

@@ -0,0 +1,58 @@
+/* Simple linker script for the JOS kernel.
+   See the GNU ld 'info' manual ("info ld") to learn the syntax. */
+
+OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
+OUTPUT_ARCH(i386)
+ENTRY(kern_init)
+
+SECTIONS {
+	/* Load the kernel at this address: "." means the current address */
+	. = 0x100000;
+
+	.text : {
+		*(.text .stub .text.* .gnu.linkonce.t.*)
+	}
+
+	PROVIDE(etext = .);	/* Define the 'etext' symbol to this value */
+
+	.rodata : {
+		*(.rodata .rodata.* .gnu.linkonce.r.*)
+	}
+
+	/* Include debugging information in kernel memory */
+	.stab : {
+		PROVIDE(__STAB_BEGIN__ = .);
+		*(.stab);
+		PROVIDE(__STAB_END__ = .);
+		BYTE(0)		/* Force the linker to allocate space
+				   for this section */
+	}
+
+	.stabstr : {
+		PROVIDE(__STABSTR_BEGIN__ = .);
+		*(.stabstr);
+		PROVIDE(__STABSTR_END__ = .);
+		BYTE(0)		/* Force the linker to allocate space
+				   for this section */
+	}
+
+	/* Adjust the address for the data segment to the next page */
+	. = ALIGN(0x1000);
+
+	/* The data segment */
+	.data : {
+		*(.data)
+	}
+
+	PROVIDE(edata = .);
+
+	.bss : {
+		*(.bss)
+	}
+
+	PROVIDE(end = .);
+
+	/DISCARD/ : {
+		*(.eh_frame .note.GNU-stack)
+	}
+}

labcodes_answer/lab1_result/tools/sign.c

@@ -0,0 +1,43 @@
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/stat.h>
+
+int
+main(int argc, char *argv[]) {
+    struct stat st;
+    if (argc != 3) {
+        fprintf(stderr, "Usage: <input filename> <output filename>\n");
+        return -1;
+    }
+    if (stat(argv[1], &st) != 0) {
+        fprintf(stderr, "Error opening file '%s': %s\n", argv[1], strerror(errno));
+        return -1;
+    }
+    printf("'%s' size: %lld bytes\n", argv[1], (long long)st.st_size);
+    if (st.st_size > 510) {
+        fprintf(stderr, "%lld >> 510!!\n", (long long)st.st_size);
+        return -1;
+    }
+    char buf[512];
+    memset(buf, 0, sizeof(buf));
+    FILE *ifp = fopen(argv[1], "rb");
+    int size = fread(buf, 1, st.st_size, ifp);
+    if (size != st.st_size) {
+        fprintf(stderr, "read '%s' error, size is %d.\n", argv[1], size);
+        return -1;
+    }
+    fclose(ifp);
+    buf[510] = 0x55;
+    buf[511] = 0xAA;
+    FILE *ofp = fopen(argv[2], "wb+");
+    size = fwrite(buf, 1, 512, ofp);
+    if (size != 512) {
+        fprintf(stderr, "write '%s' error, size is %d.\n", argv[2], size);
+        return -1;
+    }
+    fclose(ofp);
+    printf("build 512 bytes boot sector: '%s' success!\n", argv[2]);
+    return 0;
+}
+

labcodes_answer/lab1_result/tools/vector.c

@@ -0,0 +1,28 @@
+#include <stdio.h>
+
+int
+main(void) {
+    printf(".text\n");
+    printf(".globl __alltraps\n");
+
+    int i;
+    for (i = 0; i < 256; i ++) {
+        printf(".globl vector%d\n", i);
+        printf("vector%d:\n", i);
+        if ((i < 8 || i > 14) && i != 17) {
+            printf("  pushl \\$0\n");
+        }
+        printf("  pushl $%d\n", i);
+        printf("  jmp __alltraps\n");
+    }
+    printf("\n");
+    printf("# vector table\n");
+    printf(".data\n");
+    printf(".globl __vectors\n");
+    printf("__vectors:\n");
+    for (i = 0; i < 256; i ++) {
+        printf("  .long vector%d\n", i);
+    }
+    return 0;
+}
+

labcodes_answer/lab2_result/Makefile

@@ -0,0 +1,261 @@
+PROJ	:= 5
+EMPTY	:=
+SPACE	:= $(EMPTY) $(EMPTY)
+SLASH	:= /
+
+V       := @
+
+# try to infer the correct GCCPREFX
+ifndef GCCPREFIX
+GCCPREFIX := $(shell if i386-ucore-elf-objdump -i 2>&1 | grep '^elf32-i386$$' >/dev/null 2>&1; \
+	then echo 'i386-ucore-elf-'; \
+	elif objdump -i 2>&1 | grep 'elf32-i386' >/dev/null 2>&1; \
+	then echo ''; \
+	else echo "***" 1>&2; \
+	echo "*** Error: Couldn't find an i386-ucore-elf version of GCC/binutils." 1>&2; \
+	echo "*** Is the directory with i386-ucore-elf-gcc in your PATH?" 1>&2; \
+	echo "*** If your i386-ucore-elf toolchain is installed with a command" 1>&2; \
+	echo "*** prefix other than 'i386-ucore-elf-', set your GCCPREFIX" 1>&2; \
+	echo "*** environment variable to that prefix and run 'make' again." 1>&2; \
+	echo "*** To turn off this error, run 'gmake GCCPREFIX= ...'." 1>&2; \
+	echo "***" 1>&2; exit 1; fi)
+endif
+
+# try to infer the correct QEMU
+ifndef QEMU
+QEMU := $(shell if which qemu > /dev/null; \
+	then echo 'qemu'; exit; \
+	elif which i386-ucore-elf-qemu > /dev/null; \
+	then echo 'i386-ucore-elf-qemu'; exit; \
+	else \
+	echo "***" 1>&2; \
+	echo "*** Error: Couldn't find a working QEMU executable." 1>&2; \
+	echo "*** Is the directory containing the qemu binary in your PATH" 1>&2; \
+	echo "***" 1>&2; exit 1; fi)
+endif
+
+# eliminate default suffix rules
+.SUFFIXES: .c .S .h
+
+# delete target files if there is an error (or make is interrupted)
+.DELETE_ON_ERROR:
+
+# define compiler and flags
+
+HOSTCC		:= gcc
+HOSTCFLAGS	:= -g -Wall -O2
+
+GDB		:= $(GCCPREFIX)gdb
+
+CC		:= $(GCCPREFIX)gcc
+CFLAGS	:= -fno-builtin -Wall -ggdb -m32 -gstabs -nostdinc $(DEFS)
+CFLAGS	+= $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector)
+CTYPE	:= c S
+
+LD      := $(GCCPREFIX)ld
+LDFLAGS	:= -m $(shell $(LD) -V | grep elf_i386 2>/dev/null)
+LDFLAGS	+= -nostdlib
+
+OBJCOPY := $(GCCPREFIX)objcopy
+OBJDUMP := $(GCCPREFIX)objdump
+
+COPY	:= cp
+MKDIR   := mkdir -p
+MV		:= mv
+RM		:= rm -f
+AWK		:= awk
+SED		:= sed
+SH		:= sh
+TR		:= tr
+TOUCH	:= touch -c
+
+TAR		:= tar
+ZIP		:= gzip
+
+OBJDIR	:= obj
+BINDIR	:= bin
+
+ALLOBJS	:=
+ALLDEPS	:=
+TARGETS	:=
+
+include tools/function.mk
+
+listf_cc = $(call listf,$(1),$(CTYPE))
+
+# for cc
+add_files_cc = $(call add_files,$(1),$(CC),$(CFLAGS) $(3),$(2),$(4))
+create_target_cc = $(call create_target,$(1),$(2),$(3),$(CC),$(CFLAGS))
+
+# for hostcc
+add_files_host = $(call add_files,$(1),$(HOSTCC),$(HOSTCFLAGS),$(2),$(3))
+create_target_host = $(call create_target,$(1),$(2),$(3),$(HOSTCC),$(HOSTCFLAGS))
+
+cgtype = $(patsubst %.$(2),%.$(3),$(1))
+objfile = $(call toobj,$(1))
+asmfile = $(call cgtype,$(call toobj,$(1)),o,asm)
+outfile = $(call cgtype,$(call toobj,$(1)),o,out)
+symfile = $(call cgtype,$(call toobj,$(1)),o,sym)
+
+# for match pattern
+match = $(shell echo $(2) | $(AWK) '{for(i=1;i<=NF;i++){if(match("$(1)","^"$$(i)"$$")){exit 1;}}}'; echo $$?)
+
+# >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
+# include kernel/user
+
+INCLUDE	+= libs/
+
+CFLAGS	+= $(addprefix -I,$(INCLUDE))
+
+LIBDIR	+= libs
+
+$(call add_files_cc,$(call listf_cc,$(LIBDIR)),libs,)
+
+# -------------------------------------------------------------------
+# kernel
+
+KINCLUDE	+= kern/debug/ \
+			   kern/driver/ \
+			   kern/trap/ \
+			   kern/mm/ \
+			   kern/libs/ \
+			   kern/sync/
+
+KSRCDIR		+= kern/init \
+			   kern/libs \
+			   kern/debug \
+			   kern/driver \
+			   kern/trap \
+			   kern/mm \
+			   kern/sync
+
+KCFLAGS		+= $(addprefix -I,$(KINCLUDE))
+
+$(call add_files_cc,$(call listf_cc,$(KSRCDIR)),kernel,$(KCFLAGS))
+
+KOBJS	= $(call read_packet,kernel libs)
+
+# create kernel target
+kernel = $(call totarget,kernel)
+
+$(kernel): tools/kernel.ld
+
+$(kernel): $(KOBJS)
+	@echo + ld $@
+	$(V)$(LD) $(LDFLAGS) -T tools/kernel.ld -o $@ $(KOBJS)
+	@$(OBJDUMP) -S $@ > $(call asmfile,kernel)
+	@$(OBJDUMP) -t $@ | $(SED) '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > $(call symfile,kernel)
+
+$(call create_target,kernel)
+
+# -------------------------------------------------------------------
+
+# create bootblock
+bootfiles = $(call listf_cc,boot)
+$(foreach f,$(bootfiles),$(call cc_compile,$(f),$(CC),$(CFLAGS) -Os -nostdinc))
+
+bootblock = $(call totarget,bootblock)
+
+$(bootblock): $(call toobj,boot/bootasm.S) $(call toobj,$(bootfiles)) | $(call totarget,sign)
+	@echo + ld $@
+	$(V)$(LD) $(LDFLAGS) -N -T tools/boot.ld $^ -o $(call toobj,bootblock)
+	@$(OBJDUMP) -S $(call objfile,bootblock) > $(call asmfile,bootblock)
+	@$(OBJCOPY) -S -O binary $(call objfile,bootblock) $(call outfile,bootblock)
+	@$(call totarget,sign) $(call outfile,bootblock) $(bootblock)
+
+$(call create_target,bootblock)
+
+# -------------------------------------------------------------------
+
+# create 'sign' tools
+$(call add_files_host,tools/sign.c,sign,sign)
+$(call create_target_host,sign,sign)
+
+# -------------------------------------------------------------------
+
+# create ucore.img
+UCOREIMG	:= $(call totarget,ucore.img)
+
+$(UCOREIMG): $(kernel) $(bootblock)
+	$(V)dd if=/dev/zero of=$@ count=10000
+	$(V)dd if=$(bootblock) of=$@ conv=notrunc
+	$(V)dd if=$(kernel) of=$@ seek=1 conv=notrunc
+
+$(call create_target,ucore.img)
+
+# >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
+
+$(call finish_all)
+
+IGNORE_ALLDEPS	= gdb \
+				  clean \
+				  distclean \
+				  grade \
+				  touch \
+				  print-.+ \
+				  handin
+
+ifeq ($(call match,$(MAKECMDGOALS),$(IGNORE_ALLDEPS)),0)
+-include $(ALLDEPS)
+endif
+
+# files for grade script
+
+targets: $(TARGETS)
+
+.DEFAULT_GOAL := targets
+
+QEMUOPTS = -hda $(UCOREIMG)
+
+.PHONY: qemu qemu-nox gdb debug debug-mon debug-nox
+qemu: targets
+	$(V)$(QEMU) -parallel stdio $(QEMUOPTS) -serial null
+
+qemu-nox: targets
+	$(V)$(QEMU) -serial mon:stdio $(QEMUOPTS) -nographic
+
+gdb:
+	$(V)$(GDB) -q -x tools/gdbinit
+
+debug: targets
+	$(V)$(QEMU) -S -s -parallel stdio $(QEMUOPTS) -serial null
+
+debug-mon: targets
+	$(V)$(QEMU) -S -s -monitor stdio $(QEMUOPTS) -parallel null -serial null
+
+debug-nox: targets
+	$(V)$(QEMU) -S -s -serial mon:stdio $(QEMUOPTS) -nographic
+
+.PHONY: grade touch
+
+GRADE_GDB_IN	:= .gdb.in
+GRADE_QEMU_OUT	:= .qemu.out
+HANDIN			:= lab2-handin.tar.gz
+
+TOUCH_FILES		:= kern/trap/trap.c
+
+MAKEOPTS		:= --quiet --no-print-directory
+
+grade:
+	$(V)$(MAKE) $(MAKEOPTS) clean
+	$(V)$(SH) tools/grade.sh
+
+touch:
+	$(V)$(foreach f,$(TOUCH_FILES),$(TOUCH) $(f))
+
+print-%:
+	@echo $($(shell echo $(patsubst print-%,%,$@) | $(TR) [a-z] [A-Z]))
+
+.PHONY: clean distclean handin
+clean:
+	$(V)$(RM) $(GRADE_GDB_IN) $(GRADE_QEMU_OUT)
+	$(V)$(RM) -r $(OBJDIR) $(BINDIR)
+
+distclean: clean
+	$(V)$(RM) $(HANDIN)
+
+handin: distclean
+	$(V)$(TAR) -cf - `find . -type f -o -type d | grep -v '^\.$$' | grep -v '/CVS/' \
+					| grep -v '/\.git/' | grep -v '/\.svn/' | grep -v "$(HANDIN)"` \
+					| $(ZIP) > $(HANDIN)
+

labcodes_answer/lab2_result/boot/asm.h

@@ -0,0 +1,26 @@
+#ifndef __BOOT_ASM_H__
+#define __BOOT_ASM_H__
+
+/* Assembler macros to create x86 segments */
+
+/* Normal segment */
+#define SEG_NULLASM                                             \
+    .word 0, 0;                                                 \
+    .byte 0, 0, 0, 0
+
+#define SEG_ASM(type,base,lim)                                  \
+    .word (((lim) >> 12) & 0xffff), ((base) & 0xffff);          \
+    .byte (((base) >> 16) & 0xff), (0x90 | (type)),             \
+        (0xC0 | (((lim) >> 28) & 0xf)), (((base) >> 24) & 0xff)
+
+
+/* Application segment type bits */
+#define STA_X       0x8     // Executable segment
+#define STA_E       0x4     // Expand down (non-executable segments)
+#define STA_C       0x4     // Conforming code segment (executable only)
+#define STA_W       0x2     // Writeable (non-executable segments)
+#define STA_R       0x2     // Readable (executable segments)
+#define STA_A       0x1     // Accessed
+
+#endif /* !__BOOT_ASM_H__ */
+

labcodes_answer/lab2_result/boot/bootasm.S

@@ -0,0 +1,107 @@
+#include <asm.h>
+
+# Start the CPU: switch to 32-bit protected mode, jump into C.
+# The BIOS loads this code from the first sector of the hard disk into
+# memory at physical address 0x7c00 and starts executing in real mode
+# with %cs=0 %ip=7c00.
+
+.set PROT_MODE_CSEG,        0x8                     # kernel code segment selector
+.set PROT_MODE_DSEG,        0x10                    # kernel data segment selector
+.set CR0_PE_ON,             0x1                     # protected mode enable flag
+.set SMAP,                  0x534d4150
+
+# start address should be 0:7c00, in real mode, the beginning address of the running bootloader
+.globl start
+start:
+.code16                                             # Assemble for 16-bit mode
+    cli                                             # Disable interrupts
+    cld                                             # String operations increment
+
+    # Set up the important data segment registers (DS, ES, SS).
+    xorw %ax, %ax                                   # Segment number zero
+    movw %ax, %ds                                   # -> Data Segment
+    movw %ax, %es                                   # -> Extra Segment
+    movw %ax, %ss                                   # -> Stack Segment
+
+    # Enable A20:
+    #  For backwards compatibility with the earliest PCs, physical
+    #  address line 20 is tied low, so that addresses higher than
+    #  1MB wrap around to zero by default. This code undoes this.
+seta20.1:
+    inb $0x64, %al                                  # Wait for not busy
+    testb $0x2, %al
+    jnz seta20.1
+
+    movb $0xd1, %al                                 # 0xd1 -> port 0x64
+    outb %al, $0x64
+
+seta20.2:
+    inb $0x64, %al                                  # Wait for not busy
+    testb $0x2, %al
+    jnz seta20.2
+
+    movb $0xdf, %al                                 # 0xdf -> port 0x60
+    outb %al, $0x60
+
+probe_memory:
+    movl $0, 0x8000
+    xorl %ebx, %ebx
+    movw $0x8004, %di
+start_probe:
+    movl $0xE820, %eax
+    movl $20, %ecx
+    movl $SMAP, %edx
+    int $0x15
+    jnc cont
+    movw $12345, 0x8000
+    jmp finish_probe
+cont:
+    addw $20, %di
+    incl 0x8000
+    cmpl $0, %ebx
+    jnz start_probe
+finish_probe:
+
+    # Switch from real to protected mode, using a bootstrap GDT
+    # and segment translation that makes virtual addresses
+    # identical to physical addresses, so that the
+    # effective memory map does not change during the switch.
+    lgdt gdtdesc
+    movl %cr0, %eax
+    orl $CR0_PE_ON, %eax
+    movl %eax, %cr0
+
+    # Jump to next instruction, but in 32-bit code segment.
+    # Switches processor into 32-bit mode.
+    ljmp $PROT_MODE_CSEG, $protcseg
+
+.code32                                             # Assemble for 32-bit mode
+protcseg:
+    # Set up the protected-mode data segment registers
+    movw $PROT_MODE_DSEG, %ax                       # Our data segment selector
+    movw %ax, %ds                                   # -> DS: Data Segment
+    movw %ax, %es                                   # -> ES: Extra Segment
+    movw %ax, %fs                                   # -> FS
+    movw %ax, %gs                                   # -> GS
+    movw %ax, %ss                                   # -> SS: Stack Segment
+
+    # Set up the stack pointer and call into C. The stack region is from 0--start(0x7c00)
+    movl $0x0, %ebp
+    movl $start, %esp
+    call bootmain
+
+    # If bootmain returns (it shouldn't), loop.
+spin:
+    jmp spin
+
+.data
+# Bootstrap GDT
+.p2align 2                                          # force 4 byte alignment
+gdt:
+    SEG_NULLASM                                     # null seg
+    SEG_ASM(STA_X|STA_R, 0x0, 0xffffffff)           # code seg for bootloader and kernel
+    SEG_ASM(STA_W, 0x0, 0xffffffff)                 # data seg for bootloader and kernel
+
+gdtdesc:
+    .word 0x17                                      # sizeof(gdt) - 1
+    .long gdt                                       # address gdt

labcodes_answer/lab2_result/boot/bootmain.c

@@ -0,0 +1,116 @@
+#include <defs.h>
+#include <x86.h>
+#include <elf.h>
+
+/* *********************************************************************
+ * This a dirt simple boot loader, whose sole job is to boot
+ * an ELF kernel image from the first IDE hard disk.
+ *
+ * DISK LAYOUT
+ *  * This program(bootasm.S and bootmain.c) is the bootloader.
+ *    It should be stored in the first sector of the disk.
+ *
+ *  * The 2nd sector onward holds the kernel image.
+ *
+ *  * The kernel image must be in ELF format.
+ *
+ * BOOT UP STEPS
+ *  * when the CPU boots it loads the BIOS into memory and executes it
+ *
+ *  * the BIOS intializes devices, sets of the interrupt routines, and
+ *    reads the first sector of the boot device(e.g., hard-drive)
+ *    into memory and jumps to it.
+ *
+ *  * Assuming this boot loader is stored in the first sector of the
+ *    hard-drive, this code takes over...
+ *
+ *  * control starts in bootasm.S -- which sets up protected mode,
+ *    and a stack so C code then run, then calls bootmain()
+ *
+ *  * bootmain() in this file takes over, reads in the kernel and jumps to it.
+ * */
+
+#define SECTSIZE        512
+#define ELFHDR          ((struct elfhdr *)0x10000)      // scratch space
+
+/* waitdisk - wait for disk ready */
+static void
+waitdisk(void) {
+    while ((inb(0x1F7) & 0xC0) != 0x40)
+        /* do nothing */;
+}
+
+/* readsect - read a single sector at @secno into @dst */
+static void
+readsect(void *dst, uint32_t secno) {
+    // wait for disk to be ready
+    waitdisk();
+
+    outb(0x1F2, 1);                         // count = 1
+    outb(0x1F3, secno & 0xFF);
+    outb(0x1F4, (secno >> 8) & 0xFF);
+    outb(0x1F5, (secno >> 16) & 0xFF);
+    outb(0x1F6, ((secno >> 24) & 0xF) | 0xE0);
+    outb(0x1F7, 0x20);                      // cmd 0x20 - read sectors
+
+    // wait for disk to be ready
+    waitdisk();
+
+    // read a sector
+    insl(0x1F0, dst, SECTSIZE / 4);
+}
+
+/* *
+ * readseg - read @count bytes at @offset from kernel into virtual address @va,
+ * might copy more than asked.
+ * */
+static void
+readseg(uintptr_t va, uint32_t count, uint32_t offset) {
+    uintptr_t end_va = va + count;
+
+    // round down to sector boundary
+    va -= offset % SECTSIZE;
+
+    // translate from bytes to sectors; kernel starts at sector 1
+    uint32_t secno = (offset / SECTSIZE) + 1;
+
+    // If this is too slow, we could read lots of sectors at a time.
+    // We'd write more to memory than asked, but it doesn't matter --
+    // we load in increasing order.
+    for (; va < end_va; va += SECTSIZE, secno ++) {
+        readsect((void *)va, secno);
+    }
+}
+
+/* bootmain - the entry of bootloader */
+void
+bootmain(void) {
+    // read the 1st page off disk
+    readseg((uintptr_t)ELFHDR, SECTSIZE * 8, 0);
+
+    // is this a valid ELF?
+    if (ELFHDR->e_magic != ELF_MAGIC) {
+        goto bad;
+    }
+
+    struct proghdr *ph, *eph;
+
+    // load each program segment (ignores ph flags)
+    ph = (struct proghdr *)((uintptr_t)ELFHDR + ELFHDR->e_phoff);
+    eph = ph + ELFHDR->e_phnum;
+    for (; ph < eph; ph ++) {
+        readseg(ph->p_va & 0xFFFFFF, ph->p_memsz, ph->p_offset);
+    }
+
+    // call the entry point from the ELF header
+    // note: does not return
+    ((void (*)(void))(ELFHDR->e_entry & 0xFFFFFF))();
+
+bad:
+    outw(0x8A00, 0x8A00);
+    outw(0x8A00, 0x8E00);
+
+    /* do nothing */
+    while (1);
+}
+

labcodes_answer/lab2_result/kern/debug/assert.h

@@ -0,0 +1,27 @@
+#ifndef __KERN_DEBUG_ASSERT_H__
+#define __KERN_DEBUG_ASSERT_H__
+
+#include <defs.h>
+
+void __warn(const char *file, int line, const char *fmt, ...);
+void __noreturn __panic(const char *file, int line, const char *fmt, ...);
+
+#define warn(...)                                       \
+    __warn(__FILE__, __LINE__, __VA_ARGS__)
+
+#define panic(...)                                      \
+    __panic(__FILE__, __LINE__, __VA_ARGS__)
+
+#define assert(x)                                       \
+    do {                                                \
+        if (!(x)) {                                     \
+            panic("assertion failed: %s", #x);          \
+        }                                               \
+    } while (0)
+
+// static_assert(x) will generate a compile-time error if 'x' is false.
+#define static_assert(x)                                \
+    switch (x) { case 0: case (x): ; }
+
+#endif /* !__KERN_DEBUG_ASSERT_H__ */
+

labcodes_answer/lab2_result/kern/debug/kdebug.c

@@ -0,0 +1,323 @@
+#include <defs.h>
+#include <x86.h>
+#include <stab.h>
+#include <stdio.h>
+#include <string.h>
+#include <sync.h>
+#include <kdebug.h>
+#include <kmonitor.h>
+#include <assert.h>
+
+#define STACKFRAME_DEPTH 20
+
+extern const struct stab __STAB_BEGIN__[];  // beginning of stabs table
+extern const struct stab __STAB_END__[];    // end of stabs table
+extern const char __STABSTR_BEGIN__[];      // beginning of string table
+extern const char __STABSTR_END__[];        // end of string table
+
+/* debug information about a particular instruction pointer */
+struct eipdebuginfo {
+    const char *eip_file;                   // source code filename for eip
+    int eip_line;                           // source code line number for eip
+    const char *eip_fn_name;                // name of function containing eip
+    int eip_fn_namelen;                     // length of function's name
+    uintptr_t eip_fn_addr;                  // start address of function
+    int eip_fn_narg;                        // number of function arguments
+};
+
+/* *
+ * stab_binsearch - according to the input, the initial value of
+ * range [*@region_left, *@region_right], find a single stab entry
+ * that includes the address @addr and matches the type @type,
+ * and then save its boundary to the locations that pointed
+ * by @region_left and @region_right.
+ *
+ * Some stab types are arranged in increasing order by instruction address.
+ * For example, N_FUN stabs (stab entries with n_type == N_FUN), which
+ * mark functions, and N_SO stabs, which mark source files.
+ *
+ * Given an instruction address, this function finds the single stab entry
+ * of type @type that contains that address.
+ *
+ * The search takes place within the range [*@region_left, *@region_right].
+ * Thus, to search an entire set of N stabs, you might do:
+ *
+ *      left = 0;
+ *      right = N - 1;    (rightmost stab)
+ *      stab_binsearch(stabs, &left, &right, type, addr);
+ *
+ * The search modifies *region_left and *region_right to bracket the @addr.
+ * *@region_left points to the matching stab that contains @addr,
+ * and *@region_right points just before the next stab.
+ * If *@region_left > *region_right, then @addr is not contained in any
+ * matching stab.
+ *
+ * For example, given these N_SO stabs:
+ *      Index  Type   Address
+ *      0      SO     f0100000
+ *      13     SO     f0100040
+ *      117    SO     f0100176
+ *      118    SO     f0100178
+ *      555    SO     f0100652
+ *      556    SO     f0100654
+ *      657    SO     f0100849
+ * this code:
+ *      left = 0, right = 657;
+ *      stab_binsearch(stabs, &left, &right, N_SO, 0xf0100184);
+ * will exit setting left = 118, right = 554.
+ * */
+static void
+stab_binsearch(const struct stab *stabs, int *region_left, int *region_right,
+           int type, uintptr_t addr) {
+    int l = *region_left, r = *region_right, any_matches = 0;
+
+    while (l <= r) {
+        int true_m = (l + r) / 2, m = true_m;
+
+        // search for earliest stab with right type
+        while (m >= l && stabs[m].n_type != type) {
+            m --;
+        }
+        if (m < l) {    // no match in [l, m]
+            l = true_m + 1;
+            continue;
+        }
+
+        // actual binary search
+        any_matches = 1;
+        if (stabs[m].n_value < addr) {
+            *region_left = m;
+            l = true_m + 1;
+        } else if (stabs[m].n_value > addr) {
+            *region_right = m - 1;
+            r = m - 1;
+        } else {
+            // exact match for 'addr', but continue loop to find
+            // *region_right
+            *region_left = m;
+            l = m;
+            addr ++;
+        }
+    }
+
+    if (!any_matches) {
+        *region_right = *region_left - 1;
+    }
+    else {
+        // find rightmost region containing 'addr'
+        l = *region_right;
+        for (; l > *region_left && stabs[l].n_type != type; l --)
+            /* do nothing */;
+        *region_left = l;
+    }
+}
+
+/* *
+ * debuginfo_eip - Fill in the @info structure with information about
+ * the specified instruction address, @addr.  Returns 0 if information
+ * was found, and negative if not.  But even if it returns negative it
+ * has stored some information into '*info'.
+ * */
+int
+debuginfo_eip(uintptr_t addr, struct eipdebuginfo *info) {
+    const struct stab *stabs, *stab_end;
+    const char *stabstr, *stabstr_end;
+
+    info->eip_file = "<unknown>";
+    info->eip_line = 0;
+    info->eip_fn_name = "<unknown>";
+    info->eip_fn_namelen = 9;
+    info->eip_fn_addr = addr;
+    info->eip_fn_narg = 0;
+
+    stabs = __STAB_BEGIN__;
+    stab_end = __STAB_END__;
+    stabstr = __STABSTR_BEGIN__;
+    stabstr_end = __STABSTR_END__;
+
+    // String table validity checks
+    if (stabstr_end <= stabstr || stabstr_end[-1] != 0) {
+        return -1;
+    }
+
+    // Now we find the right stabs that define the function containing
+    // 'eip'.  First, we find the basic source file containing 'eip'.
+    // Then, we look in that source file for the function.  Then we look
+    // for the line number.
+
+    // Search the entire set of stabs for the source file (type N_SO).
+    int lfile = 0, rfile = (stab_end - stabs) - 1;
+    stab_binsearch(stabs, &lfile, &rfile, N_SO, addr);
+    if (lfile == 0)
+        return -1;
+
+    // Search within that file's stabs for the function definition
+    // (N_FUN).
+    int lfun = lfile, rfun = rfile;
+    int lline, rline;
+    stab_binsearch(stabs, &lfun, &rfun, N_FUN, addr);
+
+    if (lfun <= rfun) {
+        // stabs[lfun] points to the function name
+        // in the string table, but check bounds just in case.
+        if (stabs[lfun].n_strx < stabstr_end - stabstr) {
+            info->eip_fn_name = stabstr + stabs[lfun].n_strx;
+        }
+        info->eip_fn_addr = stabs[lfun].n_value;
+        addr -= info->eip_fn_addr;
+        // Search within the function definition for the line number.
+        lline = lfun;
+        rline = rfun;
+    } else {
+        // Couldn't find function stab!  Maybe we're in an assembly
+        // file.  Search the whole file for the line number.
+        info->eip_fn_addr = addr;
+        lline = lfile;
+        rline = rfile;
+    }
+    info->eip_fn_namelen = strfind(info->eip_fn_name, ':') - info->eip_fn_name;
+
+    // Search within [lline, rline] for the line number stab.
+    // If found, set info->eip_line to the right line number.
+    // If not found, return -1.
+    stab_binsearch(stabs, &lline, &rline, N_SLINE, addr);
+    if (lline <= rline) {
+        info->eip_line = stabs[rline].n_desc;
+    } else {
+        return -1;
+    }
+
+    // Search backwards from the line number for the relevant filename stab.
+    // We can't just use the "lfile" stab because inlined functions
+    // can interpolate code from a different file!
+    // Such included source files use the N_SOL stab type.
+    while (lline >= lfile
+           && stabs[lline].n_type != N_SOL
+           && (stabs[lline].n_type != N_SO || !stabs[lline].n_value)) {
+        lline --;
+    }
+    if (lline >= lfile && stabs[lline].n_strx < stabstr_end - stabstr) {
+        info->eip_file = stabstr + stabs[lline].n_strx;
+    }
+
+    // Set eip_fn_narg to the number of arguments taken by the function,
+    // or 0 if there was no containing function.
+    if (lfun < rfun) {
+        for (lline = lfun + 1;
+             lline < rfun && stabs[lline].n_type == N_PSYM;
+             lline ++) {
+            info->eip_fn_narg ++;
+        }
+    }
+    return 0;
+}
+
+/* *
+ * print_kerninfo - print the information about kernel, including the location
+ * of kernel entry, the start addresses of data and text segements, the start
+ * address of free memory and how many memory that kernel has used.
+ * */
+void
+print_kerninfo(void) {
+    extern char etext[], edata[], end[], kern_init[];
+    cprintf("Special kernel symbols:\n");
+    cprintf("  entry  0x%08x (phys)\n", kern_init);
+    cprintf("  etext  0x%08x (phys)\n", etext);
+    cprintf("  edata  0x%08x (phys)\n", edata);
+    cprintf("  end    0x%08x (phys)\n", end);
+    cprintf("Kernel executable memory footprint: %dKB\n", (end - kern_init + 1023)/1024);
+}
+
+/* *
+ * print_debuginfo - read and print the stat information for the address @eip,
+ * and info.eip_fn_addr should be the first address of the related function.
+ * */
+void
+print_debuginfo(uintptr_t eip) {
+    struct eipdebuginfo info;
+    if (debuginfo_eip(eip, &info) != 0) {
+        cprintf("    <unknow>: -- 0x%08x --\n", eip);
+    }
+    else {
+        char fnname[256];
+        int j;
+        for (j = 0; j < info.eip_fn_namelen; j ++) {
+            fnname[j] = info.eip_fn_name[j];
+        }
+        fnname[j] = '\0';
+        cprintf("    %s:%d: %s+%d\n", info.eip_file, info.eip_line,
+                fnname, eip - info.eip_fn_addr);
+    }
+}
+
+static __noinline uint32_t
+read_eip(void) {
+    uint32_t eip;
+    asm volatile("movl 4(%%ebp), %0" : "=r" (eip));
+    return eip;
+}
+
+/* *
+ * print_stackframe - print a list of the saved eip values from the nested 'call'
+ * instructions that led to the current point of execution
+ *
+ * The x86 stack pointer, namely esp, points to the lowest location on the stack
+ * that is currently in use. Everything below that location in stack is free. Pushing
+ * a value onto the stack will invole decreasing the stack pointer and then writing
+ * the value to the place that stack pointer pointes to. And popping a value do the
+ * opposite.
+ *
+ * The ebp (base pointer) register, in contrast, is associated with the stack
+ * primarily by software convention. On entry to a C function, the function's
+ * prologue code normally saves the previous function's base pointer by pushing
+ * it onto the stack, and then copies the current esp value into ebp for the duration
+ * of the function. If all the functions in a program obey this convention,
+ * then at any given point during the program's execution, it is possible to trace
+ * back through the stack by following the chain of saved ebp pointers and determining
+ * exactly what nested sequence of function calls caused this particular point in the
+ * program to be reached. This capability can be particularly useful, for example,
+ * when a particular function causes an assert failure or panic because bad arguments
+ * were passed to it, but you aren't sure who passed the bad arguments. A stack
+ * backtrace lets you find the offending function.
+ *
+ * The inline function read_ebp() can tell us the value of current ebp. And the
+ * non-inline function read_eip() is useful, it can read the value of current eip,
+ * since while calling this function, read_eip() can read the caller's eip from
+ * stack easily.
+ *
+ * In print_debuginfo(), the function debuginfo_eip() can get enough information about
+ * calling-chain. Finally print_stackframe() will trace and print them for debugging.
+ *
+ * Note that, the length of ebp-chain is limited. In boot/bootasm.S, before jumping
+ * to the kernel entry, the value of ebp has been set to zero, that's the boundary.
+ * */
+void
+print_stackframe(void) {
+     /* LAB1 YOUR CODE : STEP 1 */
+     /* (1) call read_ebp() to get the value of ebp. the type is (uint32_t);
+      * (2) call read_eip() to get the value of eip. the type is (uint32_t);
+      * (3) from 0 .. STACKFRAME_DEPTH
+      *    (3.1) printf value of ebp, eip
+      *    (3.2) (uint32_t)calling arguments [0..4] = the contents in address (unit32_t)ebp +2 [0..4]
+      *    (3.3) cprintf("\n");
+      *    (3.4) call print_debuginfo(eip-1) to print the C calling function name and line number, etc.
+      *    (3.5) popup a calling stackframe
+      *           NOTICE: the calling funciton's return addr eip  = ss:[ebp+4]
+      *                   the calling funciton's ebp = ss:[ebp]
+      */
+    uint32_t ebp = read_ebp(), eip = read_eip();
+
+    int i, j;
+    for (i = 0; ebp != 0 && i < STACKFRAME_DEPTH; i ++) {
+        cprintf("ebp:0x%08x eip:0x%08x args:", ebp, eip);
+        uint32_t *args = (uint32_t *)ebp + 2;
+        for (j = 0; j < 4; j ++) {
+            cprintf("0x%08x ", args[j]);
+        }
+        cprintf("\n");
+        print_debuginfo(eip - 1);
+        eip = ((uint32_t *)ebp)[1];
+        ebp = ((uint32_t *)ebp)[0];
+    }
+}
+

labcodes_answer/lab2_result/kern/debug/kdebug.h

@@ -0,0 +1,12 @@
+#ifndef __KERN_DEBUG_KDEBUG_H__
+#define __KERN_DEBUG_KDEBUG_H__
+
+#include <defs.h>
+#include <trap.h>
+
+void print_kerninfo(void);
+void print_stackframe(void);
+void print_debuginfo(uintptr_t eip);
+
+#endif /* !__KERN_DEBUG_KDEBUG_H__ */
+

labcodes_answer/lab2_result/kern/debug/kmonitor.c

@@ -0,0 +1,132 @@
+#include <stdio.h>
+#include <string.h>
+#include <mmu.h>
+#include <trap.h>
+#include <kmonitor.h>
+#include <kdebug.h>
+
+/* *
+ * Simple command-line kernel monitor useful for controlling the
+ * kernel and exploring the system interactively.
+ * */
+
+struct command {
+    const char *name;
+    const char *desc;
+    // return -1 to force monitor to exit
+    int(*func)(int argc, char **argv, struct trapframe *tf);
+};
+
+static struct command commands[] = {
+    {"help", "Display this list of commands.", mon_help},
+    {"kerninfo", "Display information about the kernel.", mon_kerninfo},
+    {"backtrace", "Print backtrace of stack frame.", mon_backtrace},
+};
+
+/* return if kernel is panic, in kern/debug/panic.c */
+bool is_kernel_panic(void);
+
+#define NCOMMANDS (sizeof(commands)/sizeof(struct command))
+
+/***** Kernel monitor command interpreter *****/
+
+#define MAXARGS         16
+#define WHITESPACE      " \t\n\r"
+
+/* parse - parse the command buffer into whitespace-separated arguments */
+static int
+parse(char *buf, char **argv) {
+    int argc = 0;
+    while (1) {
+        // find global whitespace
+        while (*buf != '\0' && strchr(WHITESPACE, *buf) != NULL) {
+            *buf ++ = '\0';
+        }
+        if (*buf == '\0') {
+            break;
+        }
+
+        // save and scan past next arg
+        if (argc == MAXARGS - 1) {
+            cprintf("Too many arguments (max %d).\n", MAXARGS);
+        }
+        argv[argc ++] = buf;
+        while (*buf != '\0' && strchr(WHITESPACE, *buf) == NULL) {
+            buf ++;
+        }
+    }
+    return argc;
+}
+
+/* *
+ * runcmd - parse the input string, split it into separated arguments
+ * and then lookup and invoke some related commands/
+ * */
+static int
+runcmd(char *buf, struct trapframe *tf) {
+    char *argv[MAXARGS];
+    int argc = parse(buf, argv);
+    if (argc == 0) {
+        return 0;
+    }
+    int i;
+    for (i = 0; i < NCOMMANDS; i ++) {
+        if (strcmp(commands[i].name, argv[0]) == 0) {
+            return commands[i].func(argc - 1, argv + 1, tf);
+        }
+    }
+    cprintf("Unknown command '%s'\n", argv[0]);
+    return 0;
+}
+
+/***** Implementations of basic kernel monitor commands *****/
+
+void
+kmonitor(struct trapframe *tf) {
+    cprintf("Welcome to the kernel debug monitor!!\n");
+    cprintf("Type 'help' for a list of commands.\n");
+
+    if (tf != NULL) {
+        print_trapframe(tf);
+    }
+
+    char *buf;
+    while (1) {
+        if ((buf = readline("K> ")) != NULL) {
+            if (runcmd(buf, tf) < 0) {
+                break;
+            }
+        }
+    }
+}
+
+/* mon_help - print the information about mon_* functions */
+int
+mon_help(int argc, char **argv, struct trapframe *tf) {
+    int i;
+    for (i = 0; i < NCOMMANDS; i ++) {
+        cprintf("%s - %s\n", commands[i].name, commands[i].desc);
+    }
+    return 0;
+}
+
+/* *
+ * mon_kerninfo - call print_kerninfo in kern/debug/kdebug.c to
+ * print the memory occupancy in kernel.
+ * */
+int
+mon_kerninfo(int argc, char **argv, struct trapframe *tf) {
+    print_kerninfo();
+    return 0;
+}
+
+/* *
+ * mon_backtrace - call print_stackframe in kern/debug/kdebug.c to
+ * print a backtrace of the stack.
+ * */
+int
+mon_backtrace(int argc, char **argv, struct trapframe *tf) {
+    print_stackframe();
+    return 0;
+}
+

labcodes_answer/lab2_result/kern/debug/kmonitor.h

@@ -0,0 +1,19 @@
+#ifndef __KERN_DEBUG_MONITOR_H__
+#define __KERN_DEBUG_MONITOR_H__
+
+#include <trap.h>
+
+void kmonitor(struct trapframe *tf);
+
+int mon_help(int argc, char **argv, struct trapframe *tf);
+int mon_kerninfo(int argc, char **argv, struct trapframe *tf);
+int mon_backtrace(int argc, char **argv, struct trapframe *tf);
+int mon_continue(int argc, char **argv, struct trapframe *tf);
+int mon_step(int argc, char **argv, struct trapframe *tf);
+int mon_breakpoint(int argc, char **argv, struct trapframe *tf);
+int mon_watchpoint(int argc, char **argv, struct trapframe *tf);
+int mon_delete_dr(int argc, char **argv, struct trapframe *tf);
+int mon_list_dr(int argc, char **argv, struct trapframe *tf);
+
+#endif /* !__KERN_DEBUG_MONITOR_H__ */
+

labcodes_answer/lab2_result/kern/debug/panic.c

@@ -0,0 +1,49 @@
+#include <defs.h>
+#include <stdio.h>
+#include <intr.h>
+#include <kmonitor.h>
+
+static bool is_panic = 0;
+
+/* *
+ * __panic - __panic is called on unresolvable fatal errors. it prints
+ * "panic: 'message'", and then enters the kernel monitor.
+ * */
+void
+__panic(const char *file, int line, const char *fmt, ...) {
+    if (is_panic) {
+        goto panic_dead;
+    }
+    is_panic = 1;
+
+    // print the 'message'
+    va_list ap;
+    va_start(ap, fmt);
+    cprintf("kernel panic at %s:%d:\n    ", file, line);
+    vcprintf(fmt, ap);
+    cprintf("\n");
+    va_end(ap);
+
+panic_dead:
+    intr_disable();
+    while (1) {
+        kmonitor(NULL);
+    }
+}
+
+/* __warn - like panic, but don't */
+void
+__warn(const char *file, int line, const char *fmt, ...) {
+    va_list ap;
+    va_start(ap, fmt);
+    cprintf("kernel warning at %s:%d:\n    ", file, line);
+    vcprintf(fmt, ap);
+    cprintf("\n");
+    va_end(ap);
+}
+
+bool
+is_kernel_panic(void) {
+    return is_panic;
+}
+

labcodes_answer/lab2_result/kern/debug/stab.h

@@ -0,0 +1,54 @@
+#ifndef __KERN_DEBUG_STAB_H__
+#define __KERN_DEBUG_STAB_H__
+
+#include <defs.h>
+
+/* *
+ * STABS debugging info
+ *
+ * The kernel debugger can understand some debugging information in
+ * the STABS format.  For more information on this format, see
+ * http://sources.redhat.com/gdb/onlinedocs/stabs_toc.html
+ *
+ * The constants below define some symbol types used by various debuggers
+ * and compilers.  Kernel uses the N_SO, N_SOL, N_FUN, and N_SLINE types.
+ * */
+
+#define N_GSYM      0x20    // global symbol
+#define N_FNAME     0x22    // F77 function name
+#define N_FUN       0x24    // procedure name
+#define N_STSYM     0x26    // data segment variable
+#define N_LCSYM     0x28    // bss segment variable
+#define N_MAIN      0x2a    // main function name
+#define N_PC        0x30    // global Pascal symbol
+#define N_RSYM      0x40    // register variable
+#define N_SLINE     0x44    // text segment line number
+#define N_DSLINE    0x46    // data segment line number
+#define N_BSLINE    0x48    // bss segment line number
+#define N_SSYM      0x60    // structure/union element
+#define N_SO        0x64    // main source file name
+#define N_LSYM      0x80    // stack variable
+#define N_BINCL     0x82    // include file beginning
+#define N_SOL       0x84    // included source file name
+#define N_PSYM      0xa0    // parameter variable
+#define N_EINCL     0xa2    // include file end
+#define N_ENTRY     0xa4    // alternate entry point
+#define N_LBRAC     0xc0    // left bracket
+#define N_EXCL      0xc2    // deleted include file
+#define N_RBRAC     0xe0    // right bracket
+#define N_BCOMM     0xe2    // begin common
+#define N_ECOMM     0xe4    // end common
+#define N_ECOML     0xe8    // end common (local name)
+#define N_LENG      0xfe    // length of preceding entry
+
+/* Entries in the STABS table are formatted as follows. */
+struct stab {
+    uint32_t n_strx;        // index into string table of name
+    uint8_t n_type;         // type of symbol
+    uint8_t n_other;        // misc info (usually empty)
+    uint16_t n_desc;        // description field
+    uintptr_t n_value;      // value of symbol
+};
+
+#endif /* !__KERN_DEBUG_STAB_H__ */
+

labcodes_answer/lab2_result/kern/driver/clock.c

@@ -0,0 +1,45 @@
+#include <x86.h>
+#include <trap.h>
+#include <stdio.h>
+#include <picirq.h>
+
+/* *
+ * Support for time-related hardware gadgets - the 8253 timer,
+ * which generates interruptes on IRQ-0.
+ * */
+
+#define IO_TIMER1           0x040               // 8253 Timer #1
+
+/* *
+ * Frequency of all three count-down timers; (TIMER_FREQ/freq)
+ * is the appropriate count to generate a frequency of freq Hz.
+ * */
+
+#define TIMER_FREQ      1193182
+#define TIMER_DIV(x)    ((TIMER_FREQ + (x) / 2) / (x))
+
+#define TIMER_MODE      (IO_TIMER1 + 3)         // timer mode port
+#define TIMER_SEL0      0x00                    // select counter 0
+#define TIMER_RATEGEN   0x04                    // mode 2, rate generator
+#define TIMER_16BIT     0x30                    // r/w counter 16 bits, LSB first
+
+volatile size_t ticks;
+
+/* *
+ * clock_init - initialize 8253 clock to interrupt 100 times per second,
+ * and then enable IRQ_TIMER.
+ * */
+void
+clock_init(void) {
+    // set 8253 timer-chip
+    outb(TIMER_MODE, TIMER_SEL0 | TIMER_RATEGEN | TIMER_16BIT);
+    outb(IO_TIMER1, TIMER_DIV(100) % 256);
+    outb(IO_TIMER1, TIMER_DIV(100) / 256);
+
+    // initialize time counter 'ticks' to zero
+    ticks = 0;
+
+    cprintf("++ setup timer interrupts\n");
+    pic_enable(IRQ_TIMER);
+}
+

labcodes_answer/lab2_result/kern/driver/clock.h

@@ -0,0 +1,11 @@
+#ifndef __KERN_DRIVER_CLOCK_H__
+#define __KERN_DRIVER_CLOCK_H__
+
+#include <defs.h>
+
+extern volatile size_t ticks;
+
+void clock_init(void);
+
+#endif /* !__KERN_DRIVER_CLOCK_H__ */
+

labcodes_answer/lab2_result/kern/driver/console.c

@@ -0,0 +1,465 @@
+#include <defs.h>
+#include <x86.h>
+#include <stdio.h>
+#include <string.h>
+#include <kbdreg.h>
+#include <picirq.h>
+#include <trap.h>
+#include <memlayout.h>
+#include <sync.h>
+
+/* stupid I/O delay routine necessitated by historical PC design flaws */
+static void
+delay(void) {
+    inb(0x84);
+    inb(0x84);
+    inb(0x84);
+    inb(0x84);
+}
+
+/***** Serial I/O code *****/
+#define COM1            0x3F8
+
+#define COM_RX          0       // In:  Receive buffer (DLAB=0)
+#define COM_TX          0       // Out: Transmit buffer (DLAB=0)
+#define COM_DLL         0       // Out: Divisor Latch Low (DLAB=1)
+#define COM_DLM         1       // Out: Divisor Latch High (DLAB=1)
+#define COM_IER         1       // Out: Interrupt Enable Register
+#define COM_IER_RDI     0x01    // Enable receiver data interrupt
+#define COM_IIR         2       // In:  Interrupt ID Register
+#define COM_FCR         2       // Out: FIFO Control Register
+#define COM_LCR         3       // Out: Line Control Register
+#define COM_LCR_DLAB    0x80    // Divisor latch access bit
+#define COM_LCR_WLEN8   0x03    // Wordlength: 8 bits
+#define COM_MCR         4       // Out: Modem Control Register
+#define COM_MCR_RTS     0x02    // RTS complement
+#define COM_MCR_DTR     0x01    // DTR complement
+#define COM_MCR_OUT2    0x08    // Out2 complement
+#define COM_LSR         5       // In:  Line Status Register
+#define COM_LSR_DATA    0x01    // Data available
+#define COM_LSR_TXRDY   0x20    // Transmit buffer avail
+#define COM_LSR_TSRE    0x40    // Transmitter off
+
+#define MONO_BASE       0x3B4
+#define MONO_BUF        0xB0000
+#define CGA_BASE        0x3D4
+#define CGA_BUF         0xB8000
+#define CRT_ROWS        25
+#define CRT_COLS        80
+#define CRT_SIZE        (CRT_ROWS * CRT_COLS)
+
+#define LPTPORT         0x378
+
+static uint16_t *crt_buf;
+static uint16_t crt_pos;
+static uint16_t addr_6845;
+
+/* TEXT-mode CGA/VGA display output */
+
+static void
+cga_init(void) {
+    volatile uint16_t *cp = (uint16_t *)(CGA_BUF + KERNBASE);
+    uint16_t was = *cp;
+    *cp = (uint16_t) 0xA55A;
+    if (*cp != 0xA55A) {
+        cp = (uint16_t*)(MONO_BUF + KERNBASE);
+        addr_6845 = MONO_BASE;
+    } else {
+        *cp = was;
+        addr_6845 = CGA_BASE;
+    }
+
+    // Extract cursor location
+    uint32_t pos;
+    outb(addr_6845, 14);
+    pos = inb(addr_6845 + 1) << 8;
+    outb(addr_6845, 15);
+    pos |= inb(addr_6845 + 1);
+
+    crt_buf = (uint16_t*) cp;
+    crt_pos = pos;
+}
+
+static bool serial_exists = 0;
+
+static void
+serial_init(void) {
+    // Turn off the FIFO
+    outb(COM1 + COM_FCR, 0);
+
+    // Set speed; requires DLAB latch
+    outb(COM1 + COM_LCR, COM_LCR_DLAB);
+    outb(COM1 + COM_DLL, (uint8_t) (115200 / 9600));
+    outb(COM1 + COM_DLM, 0);
+
+    // 8 data bits, 1 stop bit, parity off; turn off DLAB latch
+    outb(COM1 + COM_LCR, COM_LCR_WLEN8 & ~COM_LCR_DLAB);
+
+    // No modem controls
+    outb(COM1 + COM_MCR, 0);
+    // Enable rcv interrupts
+    outb(COM1 + COM_IER, COM_IER_RDI);
+
+    // Clear any preexisting overrun indications and interrupts
+    // Serial port doesn't exist if COM_LSR returns 0xFF
+    serial_exists = (inb(COM1 + COM_LSR) != 0xFF);
+    (void) inb(COM1+COM_IIR);
+    (void) inb(COM1+COM_RX);
+
+    if (serial_exists) {
+        pic_enable(IRQ_COM1);
+    }
+}
+
+static void
+lpt_putc_sub(int c) {
+    int i;
+    for (i = 0; !(inb(LPTPORT + 1) & 0x80) && i < 12800; i ++) {
+        delay();
+    }
+    outb(LPTPORT + 0, c);
+    outb(LPTPORT + 2, 0x08 | 0x04 | 0x01);
+    outb(LPTPORT + 2, 0x08);
+}
+
+/* lpt_putc - copy console output to parallel port */
+static void
+lpt_putc(int c) {
+    if (c != '\b') {
+        lpt_putc_sub(c);
+    }
+    else {
+        lpt_putc_sub('\b');
+        lpt_putc_sub(' ');
+        lpt_putc_sub('\b');
+    }
+}
+
+/* cga_putc - print character to console */
+static void
+cga_putc(int c) {
+    // set black on white
+    if (!(c & ~0xFF)) {
+        c |= 0x0700;
+    }
+
+    switch (c & 0xff) {
+    case '\b':
+        if (crt_pos > 0) {
+            crt_pos --;
+            crt_buf[crt_pos] = (c & ~0xff) | ' ';
+        }
+        break;
+    case '\n':
+        crt_pos += CRT_COLS;
+    case '\r':
+        crt_pos -= (crt_pos % CRT_COLS);
+        break;
+    default:
+        crt_buf[crt_pos ++] = c;     // write the character
+        break;
+    }
+
+    // What is the purpose of this?
+    if (crt_pos >= CRT_SIZE) {
+        int i;
+        memmove(crt_buf, crt_buf + CRT_COLS, (CRT_SIZE - CRT_COLS) * sizeof(uint16_t));
+        for (i = CRT_SIZE - CRT_COLS; i < CRT_SIZE; i ++) {
+            crt_buf[i] = 0x0700 | ' ';
+        }
+        crt_pos -= CRT_COLS;
+    }
+
+    // move that little blinky thing
+    outb(addr_6845, 14);
+    outb(addr_6845 + 1, crt_pos >> 8);
+    outb(addr_6845, 15);
+    outb(addr_6845 + 1, crt_pos);
+}
+
+static void
+serial_putc_sub(int c) {
+    int i;
+    for (i = 0; !(inb(COM1 + COM_LSR) & COM_LSR_TXRDY) && i < 12800; i ++) {
+        delay();
+    }
+    outb(COM1 + COM_TX, c);
+}
+
+/* serial_putc - print character to serial port */
+static void
+serial_putc(int c) {
+    if (c != '\b') {
+        serial_putc_sub(c);
+    }
+    else {
+        serial_putc_sub('\b');
+        serial_putc_sub(' ');
+        serial_putc_sub('\b');
+    }
+}
+
+/* *
+ * Here we manage the console input buffer, where we stash characters
+ * received from the keyboard or serial port whenever the corresponding
+ * interrupt occurs.
+ * */
+
+#define CONSBUFSIZE 512
+
+static struct {
+    uint8_t buf[CONSBUFSIZE];
+    uint32_t rpos;
+    uint32_t wpos;
+} cons;
+
+/* *
+ * cons_intr - called by device interrupt routines to feed input
+ * characters into the circular console input buffer.
+ * */
+static void
+cons_intr(int (*proc)(void)) {
+    int c;
+    while ((c = (*proc)()) != -1) {
+        if (c != 0) {
+            cons.buf[cons.wpos ++] = c;
+            if (cons.wpos == CONSBUFSIZE) {
+                cons.wpos = 0;
+            }
+        }
+    }
+}
+
+/* serial_proc_data - get data from serial port */
+static int
+serial_proc_data(void) {
+    if (!(inb(COM1 + COM_LSR) & COM_LSR_DATA)) {
+        return -1;
+    }
+    int c = inb(COM1 + COM_RX);
+    if (c == 127) {
+        c = '\b';
+    }
+    return c;
+}
+
+/* serial_intr - try to feed input characters from serial port */
+void
+serial_intr(void) {
+    if (serial_exists) {
+        cons_intr(serial_proc_data);
+    }
+}
+
+/***** Keyboard input code *****/
+
+#define NO              0
+
+#define SHIFT           (1<<0)
+#define CTL             (1<<1)
+#define ALT             (1<<2)
+
+#define CAPSLOCK        (1<<3)
+#define NUMLOCK         (1<<4)
+#define SCROLLLOCK      (1<<5)
+
+#define E0ESC           (1<<6)
+
+static uint8_t shiftcode[256] = {
+    [0x1D] CTL,
+    [0x2A] SHIFT,
+    [0x36] SHIFT,
+    [0x38] ALT,
+    [0x9D] CTL,
+    [0xB8] ALT
+};
+
+static uint8_t togglecode[256] = {
+    [0x3A] CAPSLOCK,
+    [0x45] NUMLOCK,
+    [0x46] SCROLLLOCK
+};
+
+static uint8_t normalmap[256] = {
+    NO,   0x1B, '1',  '2',  '3',  '4',  '5',  '6',  // 0x00
+    '7',  '8',  '9',  '0',  '-',  '=',  '\b', '\t',
+    'q',  'w',  'e',  'r',  't',  'y',  'u',  'i',  // 0x10
+    'o',  'p',  '[',  ']',  '\n', NO,   'a',  's',
+    'd',  'f',  'g',  'h',  'j',  'k',  'l',  ';',  // 0x20
+    '\'', '`',  NO,   '\\', 'z',  'x',  'c',  'v',
+    'b',  'n',  'm',  ',',  '.',  '/',  NO,   '*',  // 0x30
+    NO,   ' ',  NO,   NO,   NO,   NO,   NO,   NO,
+    NO,   NO,   NO,   NO,   NO,   NO,   NO,   '7',  // 0x40
+    '8',  '9',  '-',  '4',  '5',  '6',  '+',  '1',
+    '2',  '3',  '0',  '.',  NO,   NO,   NO,   NO,   // 0x50
+    [0xC7] KEY_HOME,    [0x9C] '\n' /*KP_Enter*/,
+    [0xB5] '/' /*KP_Div*/,  [0xC8] KEY_UP,
+    [0xC9] KEY_PGUP,    [0xCB] KEY_LF,
+    [0xCD] KEY_RT,      [0xCF] KEY_END,
+    [0xD0] KEY_DN,      [0xD1] KEY_PGDN,
+    [0xD2] KEY_INS,     [0xD3] KEY_DEL
+};
+
+static uint8_t shiftmap[256] = {
+    NO,   033,  '!',  '@',  '#',  '$',  '%',  '^',  // 0x00
+    '&',  '*',  '(',  ')',  '_',  '+',  '\b', '\t',
+    'Q',  'W',  'E',  'R',  'T',  'Y',  'U',  'I',  // 0x10
+    'O',  'P',  '{',  '}',  '\n', NO,   'A',  'S',
+    'D',  'F',  'G',  'H',  'J',  'K',  'L',  ':',  // 0x20
+    '"',  '~',  NO,   '|',  'Z',  'X',  'C',  'V',
+    'B',  'N',  'M',  '<',  '>',  '?',  NO,   '*',  // 0x30
+    NO,   ' ',  NO,   NO,   NO,   NO,   NO,   NO,
+    NO,   NO,   NO,   NO,   NO,   NO,   NO,   '7',  // 0x40
+    '8',  '9',  '-',  '4',  '5',  '6',  '+',  '1',
+    '2',  '3',  '0',  '.',  NO,   NO,   NO,   NO,   // 0x50
+    [0xC7] KEY_HOME,    [0x9C] '\n' /*KP_Enter*/,
+    [0xB5] '/' /*KP_Div*/,  [0xC8] KEY_UP,
+    [0xC9] KEY_PGUP,    [0xCB] KEY_LF,
+    [0xCD] KEY_RT,      [0xCF] KEY_END,
+    [0xD0] KEY_DN,      [0xD1] KEY_PGDN,
+    [0xD2] KEY_INS,     [0xD3] KEY_DEL
+};
+
+#define C(x) (x - '@')
+
+static uint8_t ctlmap[256] = {
+    NO,      NO,      NO,      NO,      NO,      NO,      NO,      NO,
+    NO,      NO,      NO,      NO,      NO,      NO,      NO,      NO,
+    C('Q'),  C('W'),  C('E'),  C('R'),  C('T'),  C('Y'),  C('U'),  C('I'),
+    C('O'),  C('P'),  NO,      NO,      '\r',    NO,      C('A'),  C('S'),
+    C('D'),  C('F'),  C('G'),  C('H'),  C('J'),  C('K'),  C('L'),  NO,
+    NO,      NO,      NO,      C('\\'), C('Z'),  C('X'),  C('C'),  C('V'),
+    C('B'),  C('N'),  C('M'),  NO,      NO,      C('/'),  NO,      NO,
+    [0x97] KEY_HOME,
+    [0xB5] C('/'),      [0xC8] KEY_UP,
+    [0xC9] KEY_PGUP,    [0xCB] KEY_LF,
+    [0xCD] KEY_RT,      [0xCF] KEY_END,
+    [0xD0] KEY_DN,      [0xD1] KEY_PGDN,
+    [0xD2] KEY_INS,     [0xD3] KEY_DEL
+};
+
+static uint8_t *charcode[4] = {
+    normalmap,
+    shiftmap,
+    ctlmap,
+    ctlmap
+};
+
+/* *
+ * kbd_proc_data - get data from keyboard
+ *
+ * The kbd_proc_data() function gets data from the keyboard.
+ * If we finish a character, return it, else 0. And return -1 if no data.
+ * */
+static int
+kbd_proc_data(void) {
+    int c;
+    uint8_t data;
+    static uint32_t shift;
+
+    if ((inb(KBSTATP) & KBS_DIB) == 0) {
+        return -1;
+    }
+
+    data = inb(KBDATAP);
+
+    if (data == 0xE0) {
+        // E0 escape character
+        shift |= E0ESC;
+        return 0;
+    } else if (data & 0x80) {
+        // Key released
+        data = (shift & E0ESC ? data : data & 0x7F);
+        shift &= ~(shiftcode[data] | E0ESC);
+        return 0;
+    } else if (shift & E0ESC) {
+        // Last character was an E0 escape; or with 0x80
+        data |= 0x80;
+        shift &= ~E0ESC;
+    }
+
+    shift |= shiftcode[data];
+    shift ^= togglecode[data];
+
+    c = charcode[shift & (CTL | SHIFT)][data];
+    if (shift & CAPSLOCK) {
+        if ('a' <= c && c <= 'z')
+            c += 'A' - 'a';
+        else if ('A' <= c && c <= 'Z')
+            c += 'a' - 'A';
+    }
+
+    // Process special keys
+    // Ctrl-Alt-Del: reboot
+    if (!(~shift & (CTL | ALT)) && c == KEY_DEL) {
+        cprintf("Rebooting!\n");
+        outb(0x92, 0x3); // courtesy of Chris Frost
+    }
+    return c;
+}
+
+/* kbd_intr - try to feed input characters from keyboard */
+static void
+kbd_intr(void) {
+    cons_intr(kbd_proc_data);
+}
+
+static void
+kbd_init(void) {
+    // drain the kbd buffer
+    kbd_intr();
+    pic_enable(IRQ_KBD);
+}
+
+/* cons_init - initializes the console devices */
+void
+cons_init(void) {
+    cga_init();
+    serial_init();
+    kbd_init();
+    if (!serial_exists) {
+        cprintf("serial port does not exist!!\n");
+    }
+}
+
+/* cons_putc - print a single character @c to console devices */
+void
+cons_putc(int c) {
+    bool intr_flag;
+    local_intr_save(intr_flag);
+    {
+        lpt_putc(c);
+        cga_putc(c);
+        serial_putc(c);
+    }
+    local_intr_restore(intr_flag);
+}
+
+/* *
+ * cons_getc - return the next input character from console,
+ * or 0 if none waiting.
+ * */
+int
+cons_getc(void) {
+    int c = 0;
+    bool intr_flag;
+    local_intr_save(intr_flag);
+    {
+        // poll for any pending input characters,
+        // so that this function works even when interrupts are disabled
+        // (e.g., when called from the kernel monitor).
+        serial_intr();
+        kbd_intr();
+
+        // grab the next character from the input buffer.
+        if (cons.rpos != cons.wpos) {
+            c = cons.buf[cons.rpos ++];
+            if (cons.rpos == CONSBUFSIZE) {
+                cons.rpos = 0;
+            }
+        }
+    }
+    local_intr_restore(intr_flag);
+    return c;
+}
+

labcodes_answer/lab2_result/kern/driver/console.h

@@ -0,0 +1,11 @@
+#ifndef __KERN_DRIVER_CONSOLE_H__
+#define __KERN_DRIVER_CONSOLE_H__
+
+void cons_init(void);
+void cons_putc(int c);
+int cons_getc(void);
+void serial_intr(void);
+void kbd_intr(void);
+
+#endif /* !__KERN_DRIVER_CONSOLE_H__ */
+

labcodes_answer/lab2_result/kern/driver/intr.c

@@ -0,0 +1,15 @@
+#include <x86.h>
+#include <intr.h>
+
+/* intr_enable - enable irq interrupt */
+void
+intr_enable(void) {
+    sti();
+}
+
+/* intr_disable - disable irq interrupt */
+void
+intr_disable(void) {
+    cli();
+}
+

labcodes_answer/lab2_result/kern/driver/intr.h

@@ -0,0 +1,8 @@
+#ifndef __KERN_DRIVER_INTR_H__
+#define __KERN_DRIVER_INTR_H__
+
+void intr_enable(void);
+void intr_disable(void);
+
+#endif /* !__KERN_DRIVER_INTR_H__ */
+

labcodes_answer/lab2_result/kern/driver/kbdreg.h

@@ -0,0 +1,84 @@
+#ifndef __KERN_DRIVER_KBDREG_H__
+#define __KERN_DRIVER_KBDREG_H__
+
+// Special keycodes
+#define KEY_HOME            0xE0
+#define KEY_END             0xE1
+#define KEY_UP              0xE2
+#define KEY_DN              0xE3
+#define KEY_LF              0xE4
+#define KEY_RT              0xE5
+#define KEY_PGUP            0xE6
+#define KEY_PGDN            0xE7
+#define KEY_INS             0xE8
+#define KEY_DEL             0xE9
+
+
+/* This is i8042reg.h + kbdreg.h from NetBSD. */
+
+#define KBSTATP             0x64    // kbd controller status port(I)
+#define KBS_DIB             0x01    // kbd data in buffer
+#define KBS_IBF             0x02    // kbd input buffer low
+#define KBS_WARM            0x04    // kbd input buffer low
+#define BS_OCMD             0x08    // kbd output buffer has command
+#define KBS_NOSEC           0x10    // kbd security lock not engaged
+#define KBS_TERR            0x20    // kbd transmission error
+#define KBS_RERR            0x40    // kbd receive error
+#define KBS_PERR            0x80    // kbd parity error
+
+#define KBCMDP              0x64    // kbd controller port(O)
+#define KBC_RAMREAD         0x20    // read from RAM
+#define KBC_RAMWRITE        0x60    // write to RAM
+#define KBC_AUXDISABLE      0xa7    // disable auxiliary port
+#define KBC_AUXENABLE       0xa8    // enable auxiliary port
+#define KBC_AUXTEST         0xa9    // test auxiliary port
+#define KBC_KBDECHO         0xd2    // echo to keyboard port
+#define KBC_AUXECHO         0xd3    // echo to auxiliary port
+#define KBC_AUXWRITE        0xd4    // write to auxiliary port
+#define KBC_SELFTEST        0xaa    // start self-test
+#define KBC_KBDTEST         0xab    // test keyboard port
+#define KBC_KBDDISABLE      0xad    // disable keyboard port
+#define KBC_KBDENABLE       0xae    // enable keyboard port
+#define KBC_PULSE0          0xfe    // pulse output bit 0
+#define KBC_PULSE1          0xfd    // pulse output bit 1
+#define KBC_PULSE2          0xfb    // pulse output bit 2
+#define KBC_PULSE3          0xf7    // pulse output bit 3
+
+#define KBDATAP             0x60    // kbd data port(I)
+#define KBOUTP              0x60    // kbd data port(O)
+
+#define K_RDCMDBYTE         0x20
+#define K_LDCMDBYTE         0x60
+
+#define KC8_TRANS           0x40    // convert to old scan codes
+#define KC8_MDISABLE        0x20    // disable mouse
+#define KC8_KDISABLE        0x10    // disable keyboard
+#define KC8_IGNSEC          0x08    // ignore security lock
+#define KC8_CPU             0x04    // exit from protected mode reset
+#define KC8_MENABLE         0x02    // enable mouse interrupt
+#define KC8_KENABLE         0x01    // enable keyboard interrupt
+#define CMDBYTE             (KC8_TRANS|KC8_CPU|KC8_MENABLE|KC8_KENABLE)
+
+/* keyboard commands */
+#define KBC_RESET           0xFF    // reset the keyboard
+#define KBC_RESEND          0xFE    // request the keyboard resend the last byte
+#define KBC_SETDEFAULT      0xF6    // resets keyboard to its power-on defaults
+#define KBC_DISABLE         0xF5    // as per KBC_SETDEFAULT, but also disable key scanning
+#define KBC_ENABLE          0xF4    // enable key scanning
+#define KBC_TYPEMATIC       0xF3    // set typematic rate and delay
+#define KBC_SETTABLE        0xF0    // set scancode translation table
+#define KBC_MODEIND         0xED    // set mode indicators(i.e. LEDs)
+#define KBC_ECHO            0xEE    // request an echo from the keyboard
+
+/* keyboard responses */
+#define KBR_EXTENDED        0xE0    // extended key sequence
+#define KBR_RESEND          0xFE    // needs resend of command
+#define KBR_ACK             0xFA    // received a valid command
+#define KBR_OVERRUN         0x00    // flooded
+#define KBR_FAILURE         0xFD    // diagnosic failure
+#define KBR_BREAK           0xF0    // break code prefix - sent on key release
+#define KBR_RSTDONE         0xAA    // reset complete
+#define KBR_ECHO            0xEE    // echo response
+
+#endif /* !__KERN_DRIVER_KBDREG_H__ */
+

labcodes_answer/lab2_result/kern/driver/picirq.c

@@ -0,0 +1,86 @@
+#include <defs.h>
+#include <x86.h>
+#include <picirq.h>
+
+// I/O Addresses of the two programmable interrupt controllers
+#define IO_PIC1             0x20    // Master (IRQs 0-7)
+#define IO_PIC2             0xA0    // Slave (IRQs 8-15)
+
+#define IRQ_SLAVE           2       // IRQ at which slave connects to master
+
+// Current IRQ mask.
+// Initial IRQ mask has interrupt 2 enabled (for slave 8259A).
+static uint16_t irq_mask = 0xFFFF & ~(1 << IRQ_SLAVE);
+static bool did_init = 0;
+
+static void
+pic_setmask(uint16_t mask) {
+    irq_mask = mask;
+    if (did_init) {
+        outb(IO_PIC1 + 1, mask);
+        outb(IO_PIC2 + 1, mask >> 8);
+    }
+}
+
+void
+pic_enable(unsigned int irq) {
+    pic_setmask(irq_mask & ~(1 << irq));
+}
+
+/* pic_init - initialize the 8259A interrupt controllers */
+void
+pic_init(void) {
+    did_init = 1;
+
+    // mask all interrupts
+    outb(IO_PIC1 + 1, 0xFF);
+    outb(IO_PIC2 + 1, 0xFF);
+
+    // Set up master (8259A-1)
+
+    // ICW1:  0001g0hi
+    //    g:  0 = edge triggering, 1 = level triggering
+    //    h:  0 = cascaded PICs, 1 = master only
+    //    i:  0 = no ICW4, 1 = ICW4 required
+    outb(IO_PIC1, 0x11);
+
+    // ICW2:  Vector offset
+    outb(IO_PIC1 + 1, IRQ_OFFSET);
+
+    // ICW3:  (master PIC) bit mask of IR lines connected to slaves
+    //        (slave PIC) 3-bit # of slave's connection to master
+    outb(IO_PIC1 + 1, 1 << IRQ_SLAVE);
+
+    // ICW4:  000nbmap
+    //    n:  1 = special fully nested mode
+    //    b:  1 = buffered mode
+    //    m:  0 = slave PIC, 1 = master PIC
+    //        (ignored when b is 0, as the master/slave role
+    //         can be hardwired).
+    //    a:  1 = Automatic EOI mode
+    //    p:  0 = MCS-80/85 mode, 1 = intel x86 mode
+    outb(IO_PIC1 + 1, 0x3);
+
+    // Set up slave (8259A-2)
+    outb(IO_PIC2, 0x11);    // ICW1
+    outb(IO_PIC2 + 1, IRQ_OFFSET + 8);  // ICW2
+    outb(IO_PIC2 + 1, IRQ_SLAVE);       // ICW3
+    // NB Automatic EOI mode doesn't tend to work on the slave.
+    // Linux source code says it's "to be investigated".
+    outb(IO_PIC2 + 1, 0x3);             // ICW4
+
+    // OCW3:  0ef01prs
+    //   ef:  0x = NOP, 10 = clear specific mask, 11 = set specific mask
+    //    p:  0 = no polling, 1 = polling mode
+    //   rs:  0x = NOP, 10 = read IRR, 11 = read ISR
+    outb(IO_PIC1, 0x68);    // clear specific mask
+    outb(IO_PIC1, 0x0a);    // read IRR by default
+
+    outb(IO_PIC2, 0x68);    // OCW3
+    outb(IO_PIC2, 0x0a);    // OCW3
+
+    if (irq_mask != 0xFFFF) {
+        pic_setmask(irq_mask);
+    }
+}
+

labcodes_answer/lab2_result/kern/driver/picirq.h

@@ -0,0 +1,10 @@
+#ifndef __KERN_DRIVER_PICIRQ_H__
+#define __KERN_DRIVER_PICIRQ_H__
+
+void pic_init(void);
+void pic_enable(unsigned int irq);
+
+#define IRQ_OFFSET      32
+
+#endif /* !__KERN_DRIVER_PICIRQ_H__ */
+

labcodes_answer/lab2_result/kern/init/entry.S

@@ -0,0 +1,49 @@
+#include <mmu.h>
+#include <memlayout.h>
+
+#define REALLOC(x) (x - KERNBASE)
+
+.text
+.globl kern_entry
+kern_entry:
+    # reload temperate gdt (second time) to remap all physical memory
+    # virtual_addr 0~4G=linear_addr&physical_addr -KERNBASE~4G-KERNBASE 
+    lgdt REALLOC(__gdtdesc)
+    movl $KERNEL_DS, %eax
+    movw %ax, %ds
+    movw %ax, %es
+    movw %ax, %ss
+
+    ljmp $KERNEL_CS, $relocated
+
+relocated:
+
+    # set ebp, esp
+    movl $0x0, %ebp
+    # the kernel stack region is from bootstack -- bootstacktop,
+    # the kernel stack size is KSTACKSIZE (8KB)defined in memlayout.h
+    movl $bootstacktop, %esp
+    # now kernel stack is ready , call the first C function
+    call kern_init
+
+# should never get here
+spin:
+    jmp spin
+
+.data
+.align PGSIZE
+    .globl bootstack
+bootstack:
+    .space KSTACKSIZE
+    .globl bootstacktop
+bootstacktop:
+
+.align 4
+__gdt:
+    SEG_NULL
+    SEG_ASM(STA_X | STA_R, - KERNBASE, 0xFFFFFFFF)      # code segment
+    SEG_ASM(STA_W, - KERNBASE, 0xFFFFFFFF)              # data segment
+__gdtdesc:
+    .word 0x17                                          # sizeof(__gdt) - 1
+    .long REALLOC(__gdt)
+

labcodes_answer/lab2_result/kern/init/init.c

@@ -0,0 +1,104 @@
+#include <defs.h>
+#include <stdio.h>
+#include <string.h>
+#include <console.h>
+#include <kdebug.h>
+#include <picirq.h>
+#include <trap.h>
+#include <clock.h>
+#include <intr.h>
+#include <pmm.h>
+
+int kern_init(void) __attribute__((noreturn));
+
+static void lab1_switch_test(void);
+
+int
+kern_init(void) {
+    extern char edata[], end[];
+    memset(edata, 0, end - edata);
+
+    cons_init();                // init the console
+
+    const char *message = "(THU.CST) os is loading ...";
+    cprintf("%s\n\n", message);
+
+    print_kerninfo();
+
+    grade_backtrace();
+
+    pmm_init();                 // init physical memory management
+
+    pic_init();                 // init interrupt controller
+    idt_init();                 // init interrupt descriptor table
+
+    clock_init();               // init clock interrupt
+    intr_enable();              // enable irq interrupt
+
+    //LAB1: CAHLLENGE 1 If you try to do it, uncomment lab1_switch_test()
+    // user/kernel mode switch test
+    //lab1_switch_test();
+
+    /* do nothing */
+    while (1);
+}
+
+void __attribute__((noinline))
+grade_backtrace2(int arg0, int arg1, int arg2, int arg3) {
+    mon_backtrace(0, NULL, NULL);
+}
+
+void __attribute__((noinline))
+grade_backtrace1(int arg0, int arg1) {
+    grade_backtrace2(arg0, (int)&arg0, arg1, (int)&arg1);
+}
+
+void __attribute__((noinline))
+grade_backtrace0(int arg0, int arg1, int arg2) {
+    grade_backtrace1(arg0, arg2);
+}
+
+void
+grade_backtrace(void) {
+    grade_backtrace0(0, (int)kern_init, 0xffff0000);
+}
+
+static void
+lab1_print_cur_status(void) {
+    static int round = 0;
+    uint16_t reg1, reg2, reg3, reg4;
+    asm volatile (
+            "mov %%cs, %0;"
+            "mov %%ds, %1;"
+            "mov %%es, %2;"
+            "mov %%ss, %3;"
+            : "=m"(reg1), "=m"(reg2), "=m"(reg3), "=m"(reg4));
+    cprintf("%d: @ring %d\n", round, reg1 & 3);
+    cprintf("%d:  cs = %x\n", round, reg1);
+    cprintf("%d:  ds = %x\n", round, reg2);
+    cprintf("%d:  es = %x\n", round, reg3);
+    cprintf("%d:  ss = %x\n", round, reg4);
+    round ++;
+}
+
+static void
+lab1_switch_to_user(void) {
+    //LAB1 CHALLENGE 1 : TODO
+}
+
+static void
+lab1_switch_to_kernel(void) {
+    //LAB1 CHALLENGE 1 :  TODO
+}
+
+static void
+lab1_switch_test(void) {
+    lab1_print_cur_status();
+    cprintf("+++ switch to  user  mode +++\n");
+    lab1_switch_to_user();
+    lab1_print_cur_status();
+    cprintf("+++ switch to kernel mode +++\n");
+    lab1_switch_to_kernel();
+    lab1_print_cur_status();
+}
+

labcodes_answer/lab2_result/kern/libs/readline.c

@@ -0,0 +1,50 @@
+#include <stdio.h>
+
+#define BUFSIZE 1024
+static char buf[BUFSIZE];
+
+/* *
+ * readline - get a line from stdin
+ * @prompt:     the string to be written to stdout
+ *
+ * The readline() function will write the input string @prompt to
+ * stdout first. If the @prompt is NULL or the empty string,
+ * no prompt is issued.
+ *
+ * This function will keep on reading characters and saving them to buffer
+ * 'buf' until '\n' or '\r' is encountered.
+ *
+ * Note that, if the length of string that will be read is longer than
+ * buffer size, the end of string will be discarded.
+ *
+ * The readline() function returns the text of the line read. If some errors
+ * are happened, NULL is returned. The return value is a global variable,
+ * thus it should be copied before it is used.
+ * */
+char *
+readline(const char *prompt) {
+    if (prompt != NULL) {
+        cprintf("%s", prompt);
+    }
+    int i = 0, c;
+    while (1) {
+        c = getchar();
+        if (c < 0) {
+            return NULL;
+        }
+        else if (c >= ' ' && i < BUFSIZE - 1) {
+            cputchar(c);
+            buf[i ++] = c;
+        }
+        else if (c == '\b' && i > 0) {
+            cputchar(c);
+            i --;
+        }
+        else if (c == '\n' || c == '\r') {
+            cputchar(c);
+            buf[i] = '\0';
+            return buf;
+        }
+    }
+}
+

labcodes_answer/lab2_result/kern/libs/stdio.c

@@ -0,0 +1,78 @@
+#include <defs.h>
+#include <stdio.h>
+#include <console.h>
+
+/* HIGH level console I/O */
+
+/* *
+ * cputch - writes a single character @c to stdout, and it will
+ * increace the value of counter pointed by @cnt.
+ * */
+static void
+cputch(int c, int *cnt) {
+    cons_putc(c);
+    (*cnt) ++;
+}
+
+/* *
+ * vcprintf - format a string and writes it to stdout
+ *
+ * The return value is the number of characters which would be
+ * written to stdout.
+ *
+ * Call this function if you are already dealing with a va_list.
+ * Or you probably want cprintf() instead.
+ * */
+int
+vcprintf(const char *fmt, va_list ap) {
+    int cnt = 0;
+    vprintfmt((void*)cputch, &cnt, fmt, ap);
+    return cnt;
+}
+
+/* *
+ * cprintf - formats a string and writes it to stdout
+ *
+ * The return value is the number of characters which would be
+ * written to stdout.
+ * */
+int
+cprintf(const char *fmt, ...) {
+    va_list ap;
+    int cnt;
+    va_start(ap, fmt);
+    cnt = vcprintf(fmt, ap);
+    va_end(ap);
+    return cnt;
+}
+
+/* cputchar - writes a single character to stdout */
+void
+cputchar(int c) {
+    cons_putc(c);
+}
+
+/* *
+ * cputs- writes the string pointed by @str to stdout and
+ * appends a newline character.
+ * */
+int
+cputs(const char *str) {
+    int cnt = 0;
+    char c;
+    while ((c = *str ++) != '\0') {
+        cputch(c, &cnt);
+    }
+    cputch('\n', &cnt);
+    return cnt;
+}
+
+/* getchar - reads a single non-zero character from stdin */
+int
+getchar(void) {
+    int c;
+    while ((c = cons_getc()) == 0)
+        /* do nothing */;
+    return c;
+}
+

labcodes_answer/lab2_result/kern/mm/default_pmm.c

@@ -0,0 +1,294 @@
+#include <pmm.h>
+#include <list.h>
+#include <string.h>
+#include <default_pmm.h>
+
+/* In the first fit algorithm, the allocator keeps a list of free blocks (known as the free list) and,
+   on receiving a request for memory, scans along the list for the first block that is large enough to
+   satisfy the request. If the chosen block is significantly larger than that requested, then it is 
+   usually split, and the remainder added to the list as another free block.
+   Please see Page 196~198, Section 8.2 of Yan Wei Ming's chinese book "Data Structure -- C programming language"
+*/
+// LAB2 EXERCISE 1: YOUR CODE
+// you should rewrite functions: default_init,default_init_memmap,default_alloc_pages, default_free_pages.
+/*
+ * Details of FFMA
+ * (1) Prepare: In order to implement the First-Fit Mem Alloc (FFMA), we should manage the free mem block use some list.
+ *              The struct free_area_t is used for the management of free mem blocks. At first you should
+ *              be familiar to the struct list in list.h. struct list is a simple doubly linked list implementation.
+ *              You should know howto USE: list_init, list_add(list_add_after), list_add_before, list_del, list_next, list_prev
+ *              Another tricky method is to transform a general list struct to a special struct (such as struct page):
+ *              you can find some MACRO: le2page (in memlayout.h), (in future labs: le2vma (in vmm.h), le2proc (in proc.h),etc.)
+ * (2) default_init: you can reuse the  demo default_init fun to init the free_list and set nr_free to 0.
+ *              free_list is used to record the free mem blocks. nr_free is the total number for free mem blocks.
+ * (3) default_init_memmap:  CALL GRAPH: kern_init --> pmm_init-->page_init-->init_memmap--> pmm_manager->init_memmap
+ *              This fun is used to init a free block (with parameter: addr_base, page_number).
+ *              First you should init each page (in memlayout.h) in this free block, include:
+ *                  p->flags should be set bit PG_property (means this page is valid. In pmm_init fun (in pmm.c),
+ *                  the bit PG_reserved is setted in p->flags)
+ *                  if this page  is free and is not the first page of free block, p->property should be set to 0.
+ *                  if this page  is free and is the first page of free block, p->property should be set to total num of block.
+ *                  p->ref should be 0, because now p is free and no reference.
+ *                  We can use p->page_link to link this page to free_list, (such as: list_add_before(&free_list, &(p->page_link)); )
+ *              Finally, we should sum the number of free mem block: nr_free+=n
+ * (4) default_alloc_pages: search find a first free block (block size >=n) in free list and reszie the free block, return the addr
+ *              of malloced block.
+ *              (4.1) So you should search freelist like this:
+ *                       list_entry_t le = &free_list;
+ *                       while((le=list_next(le)) != &free_list) {
+ *                       ....
+ *                 (4.1.1) In while loop, get the struct page and check the p->property (record the num of free block) >=n?
+ *                       struct Page *p = le2page(le, page_link);
+ *                       if(p->property >= n){ ...
+ *                 (4.1.2) If we find this p, then it' means we find a free block(block size >=n), and the first n pages can be malloced.
+ *                     Some flag bits of this page should be setted: PG_reserved =1, PG_property =0
+ *                     unlink the pages from free_list
+ *                     (4.1.2.1) If (p->property >n), we should re-caluclate number of the the rest of this free block,
+ *                           (such as: le2page(le,page_link))->property = p->property - n;)
+ *                 (4.1.3)  re-caluclate nr_free (number of the the rest of all free block)
+ *                 (4.1.4)  return p
+ *               (4.2) If we can not find a free block (block size >=n), then return NULL
+ * (5) default_free_pages: relink the pages into  free list, maybe merge small free blocks into big free blocks.
+ *               (5.1) according the base addr of withdrawed blocks, search free list, find the correct position
+ *                     (from low to high addr), and insert the pages. (may use list_next, le2page, list_add_before)
+ *               (5.2) reset the fields of pages, such as p->ref, p->flags (PageProperty)
+ *               (5.3) try to merge low addr or high addr blocks. Notice: should change some pages's p->property correctly.
+ */
+free_area_t free_area;
+
+#define free_list (free_area.free_list)
+#define nr_free (free_area.nr_free)
+
+static void
+default_init(void) {
+    list_init(&free_list);
+    nr_free = 0;
+}
+
+static void
+default_init_memmap(struct Page *base, size_t n) {
+    assert(n > 0);
+    struct Page *p = base;
+    for (; p != base + n; p ++) {
+        assert(PageReserved(p));
+        p->flags = 0;
+        SetPageProperty(p);
+        p->property = 0;
+        set_page_ref(p, 0);
+        list_add_before(&free_list, &(p->page_link));
+    }
+    nr_free += n;
+    //first block
+    base->property = n;
+}
+
+static struct Page *
+default_alloc_pages(size_t n) {
+    assert(n > 0);
+    if (n > nr_free) {
+        return NULL;
+    }
+    list_entry_t *le, *len;
+    le = &free_list;
+
+    while((le=list_next(le)) != &free_list) {
+      struct Page *p = le2page(le, page_link);
+      if(p->property >= n){
+        int i;
+        for(i=0;i<n;i++){
+          len = list_next(le);
+          struct Page *pp = le2page(le, page_link);
+          SetPageReserved(pp);
+          ClearPageProperty(pp);
+          list_del(le);
+          le = len;
+        }
+        if(p->property>n){
+          (le2page(le,page_link))->property = p->property - n;
+        }
+        ClearPageProperty(p);
+        SetPageReserved(p);
+        nr_free -= n;
+        return p;
+      }
+    }
+    return NULL;
+}
+
+static void
+default_free_pages(struct Page *base, size_t n) {
+    assert(n > 0);
+    assert(PageReserved(base));
+
+    list_entry_t *le = &free_list;
+    struct Page * p;
+    while((le=list_next(le)) != &free_list) {
+      p = le2page(le, page_link);
+      if(p>base){
+        break;
+      }
+    }
+    //list_add_before(le, base->page_link);
+    for(p=base;p<base+n;p++){
+      list_add_before(le, &(p->page_link));
+    }
+    base->flags = 0;
+    set_page_ref(base, 0);
+    ClearPageProperty(base);
+    SetPageProperty(base);
+    base->property = n;
+    
+    p = le2page(le,page_link) ;
+    if( base+n == p ){
+      base->property += p->property;
+      p->property = 0;
+    }
+    le = list_prev(&(base->page_link));
+    p = le2page(le, page_link);
+    if(le!=&free_list && p==base-1){
+      while(le!=&free_list){
+        if(p->property){
+          p->property += base->property;
+          base->property = 0;
+          break;
+        }
+        le = list_prev(le);
+        p = le2page(le,page_link);
+      }
+    }
+
+    nr_free += n;
+    return ;
+}
+
+static size_t
+default_nr_free_pages(void) {
+    return nr_free;
+}
+
+static void
+basic_check(void) {
+    struct Page *p0, *p1, *p2;
+    p0 = p1 = p2 = NULL;
+    assert((p0 = alloc_page()) != NULL);
+    assert((p1 = alloc_page()) != NULL);
+    assert((p2 = alloc_page()) != NULL);
+
+    assert(p0 != p1 && p0 != p2 && p1 != p2);
+    assert(page_ref(p0) == 0 && page_ref(p1) == 0 && page_ref(p2) == 0);
+
+    assert(page2pa(p0) < npage * PGSIZE);
+    assert(page2pa(p1) < npage * PGSIZE);
+    assert(page2pa(p2) < npage * PGSIZE);
+
+    list_entry_t free_list_store = free_list;
+    list_init(&free_list);
+    assert(list_empty(&free_list));
+
+    unsigned int nr_free_store = nr_free;
+    nr_free = 0;
+
+    assert(alloc_page() == NULL);
+
+    free_page(p0);
+    free_page(p1);
+    free_page(p2);
+    assert(nr_free == 3);
+
+    assert((p0 = alloc_page()) != NULL);
+    assert((p1 = alloc_page()) != NULL);
+    assert((p2 = alloc_page()) != NULL);
+
+    assert(alloc_page() == NULL);
+
+    free_page(p0);
+    assert(!list_empty(&free_list));
+
+    struct Page *p;
+    assert((p = alloc_page()) == p0);
+    assert(alloc_page() == NULL);
+
+    assert(nr_free == 0);
+    free_list = free_list_store;
+    nr_free = nr_free_store;
+
+    free_page(p);
+    free_page(p1);
+    free_page(p2);
+}
+
+// LAB2: below code is used to check the first fit allocation algorithm (your EXERCISE 1) 
+// NOTICE: You SHOULD NOT CHANGE basic_check, default_check functions!
+static void
+default_check(void) {
+    int count = 0, total = 0;
+    list_entry_t *le = &free_list;
+    while ((le = list_next(le)) != &free_list) {
+        struct Page *p = le2page(le, page_link);
+        assert(PageProperty(p));
+        count ++, total += p->property;
+    }
+    assert(total == nr_free_pages());
+
+    basic_check();
+
+    struct Page *p0 = alloc_pages(5), *p1, *p2;
+    assert(p0 != NULL);
+    assert(!PageProperty(p0));
+
+    list_entry_t free_list_store = free_list;
+    list_init(&free_list);
+    assert(list_empty(&free_list));
+    assert(alloc_page() == NULL);
+
+    unsigned int nr_free_store = nr_free;
+    nr_free = 0;
+
+    free_pages(p0 + 2, 3);
+    assert(alloc_pages(4) == NULL);
+    assert(PageProperty(p0 + 2) && p0[2].property == 3);
+    assert((p1 = alloc_pages(3)) != NULL);
+    assert(alloc_page() == NULL);
+    assert(p0 + 2 == p1);
+
+    p2 = p0 + 1;
+    free_page(p0);
+    free_pages(p1, 3);
+    assert(PageProperty(p0) && p0->property == 1);
+    assert(PageProperty(p1) && p1->property == 3);
+
+    assert((p0 = alloc_page()) == p2 - 1);
+    free_page(p0);
+    assert((p0 = alloc_pages(2)) == p2 + 1);
+
+    free_pages(p0, 2);
+    free_page(p2);
+
+    assert((p0 = alloc_pages(5)) != NULL);
+    assert(alloc_page() == NULL);
+
+    assert(nr_free == 0);
+    nr_free = nr_free_store;
+
+    free_list = free_list_store;
+    free_pages(p0, 5);
+
+    le = &free_list;
+    while ((le = list_next(le)) != &free_list) {
+        struct Page *p = le2page(le, page_link);
+        count --, total -= p->property;
+    }
+    assert(count == 0);
+    assert(total == 0);
+}
+
+const struct pmm_manager default_pmm_manager = {
+    .name = "default_pmm_manager",
+    .init = default_init,
+    .init_memmap = default_init_memmap,
+    .alloc_pages = default_alloc_pages,
+    .free_pages = default_free_pages,
+    .nr_free_pages = default_nr_free_pages,
+    .check = default_check,
+};
+

labcodes_answer/lab2_result/kern/mm/default_pmm.h

@@ -0,0 +1,9 @@
+#ifndef __KERN_MM_DEFAULT_PMM_H__
+#define  __KERN_MM_DEFAULT_PMM_H__
+
+#include <pmm.h>
+
+extern const struct pmm_manager default_pmm_manager;
+
+#endif /* ! __KERN_MM_DEFAULT_PMM_H__ */
+

labcodes_answer/lab2_result/kern/mm/memlayout.h

@@ -0,0 +1,130 @@
+#ifndef __KERN_MM_MEMLAYOUT_H__
+#define __KERN_MM_MEMLAYOUT_H__
+
+/* This file contains the definitions for memory management in our OS. */
+
+/* global segment number */
+#define SEG_KTEXT   1
+#define SEG_KDATA   2
+#define SEG_UTEXT   3
+#define SEG_UDATA   4
+#define SEG_TSS     5
+
+/* global descrptor numbers */
+#define GD_KTEXT    ((SEG_KTEXT) << 3)      // kernel text
+#define GD_KDATA    ((SEG_KDATA) << 3)      // kernel data
+#define GD_UTEXT    ((SEG_UTEXT) << 3)      // user text
+#define GD_UDATA    ((SEG_UDATA) << 3)      // user data
+#define GD_TSS      ((SEG_TSS) << 3)        // task segment selector
+
+#define DPL_KERNEL  (0)
+#define DPL_USER    (3)
+
+#define KERNEL_CS   ((GD_KTEXT) | DPL_KERNEL)
+#define KERNEL_DS   ((GD_KDATA) | DPL_KERNEL)
+#define USER_CS     ((GD_UTEXT) | DPL_USER)
+#define USER_DS     ((GD_UDATA) | DPL_USER)
+
+/* *
+ * Virtual memory map:                                          Permissions
+ *                                                              kernel/user
+ *
+ *     4G ------------------> +---------------------------------+
+ *                            |                                 |
+ *                            |         Empty Memory (*)        |
+ *                            |                                 |
+ *                            +---------------------------------+ 0xFB000000
+ *                            |   Cur. Page Table (Kern, RW)    | RW/-- PTSIZE
+ *     VPT -----------------> +---------------------------------+ 0xFAC00000
+ *                            |        Invalid Memory (*)       | --/--
+ *     KERNTOP -------------> +---------------------------------+ 0xF8000000
+ *                            |                                 |
+ *                            |    Remapped Physical Memory     | RW/-- KMEMSIZE
+ *                            |                                 |
+ *     KERNBASE ------------> +---------------------------------+ 0xC0000000
+ *                            |                                 |
+ *                            |                                 |
+ *                            |                                 |
+ *                            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ * (*) Note: The kernel ensures that "Invalid Memory" is *never* mapped.
+ *     "Empty Memory" is normally unmapped, but user programs may map pages
+ *     there if desired.
+ *
+ * */
+
+/* All physical memory mapped at this address */
+#define KERNBASE            0xC0000000
+#define KMEMSIZE            0x38000000                  // the maximum amount of physical memory
+#define KERNTOP             (KERNBASE + KMEMSIZE)
+
+/* *
+ * Virtual page table. Entry PDX[VPT] in the PD (Page Directory) contains
+ * a pointer to the page directory itself, thereby turning the PD into a page
+ * table, which maps all the PTEs (Page Table Entry) containing the page mappings
+ * for the entire virtual address space into that 4 Meg region starting at VPT.
+ * */
+#define VPT                 0xFAC00000
+
+#define KSTACKPAGE          2                           // # of pages in kernel stack
+#define KSTACKSIZE          (KSTACKPAGE * PGSIZE)       // sizeof kernel stack
+
+#ifndef __ASSEMBLER__
+
+#include <defs.h>
+#include <atomic.h>
+#include <list.h>
+
+typedef uintptr_t pte_t;
+typedef uintptr_t pde_t;
+
+// some constants for bios interrupt 15h AX = 0xE820
+#define E820MAX             20      // number of entries in E820MAP
+#define E820_ARM            1       // address range memory
+#define E820_ARR            2       // address range reserved
+
+struct e820map {
+    int nr_map;
+    struct {
+        uint64_t addr;
+        uint64_t size;
+        uint32_t type;
+    } __attribute__((packed)) map[E820MAX];
+};
+
+/* *
+ * struct Page - Page descriptor structures. Each Page describes one
+ * physical page. In kern/mm/pmm.h, you can find lots of useful functions
+ * that convert Page to other data types, such as phyical address.
+ * */
+struct Page {
+    int ref;                        // page frame's reference counter
+    uint32_t flags;                 // array of flags that describe the status of the page frame
+    unsigned int property;          // the num of free block, used in first fit pm manager
+    list_entry_t page_link;         // free list link
+};
+
+/* Flags describing the status of a page frame */
+#define PG_reserved                 0       // the page descriptor is reserved for kernel or unusable
+#define PG_property                 1       // the member 'property' is valid
+
+#define SetPageReserved(page)       set_bit(PG_reserved, &((page)->flags))
+#define ClearPageReserved(page)     clear_bit(PG_reserved, &((page)->flags))
+#define PageReserved(page)          test_bit(PG_reserved, &((page)->flags))
+#define SetPageProperty(page)       set_bit(PG_property, &((page)->flags))
+#define ClearPageProperty(page)     clear_bit(PG_property, &((page)->flags))
+#define PageProperty(page)          test_bit(PG_property, &((page)->flags))
+
+// convert list entry to page
+#define le2page(le, member)                 \
+    to_struct((le), struct Page, member)
+
+/* free_area_t - maintains a doubly linked list to record free (unused) pages */
+typedef struct {
+    list_entry_t free_list;         // the list header
+    unsigned int nr_free;           // # of free pages in this free list
+} free_area_t;
+
+#endif /* !__ASSEMBLER__ */
+
+#endif /* !__KERN_MM_MEMLAYOUT_H__ */
+

labcodes_answer/lab2_result/kern/mm/mmu.h

@@ -0,0 +1,272 @@
+#ifndef __KERN_MM_MMU_H__
+#define __KERN_MM_MMU_H__
+
+/* Eflags register */
+#define FL_CF           0x00000001  // Carry Flag
+#define FL_PF           0x00000004  // Parity Flag
+#define FL_AF           0x00000010  // Auxiliary carry Flag
+#define FL_ZF           0x00000040  // Zero Flag
+#define FL_SF           0x00000080  // Sign Flag
+#define FL_TF           0x00000100  // Trap Flag
+#define FL_IF           0x00000200  // Interrupt Flag
+#define FL_DF           0x00000400  // Direction Flag
+#define FL_OF           0x00000800  // Overflow Flag
+#define FL_IOPL_MASK    0x00003000  // I/O Privilege Level bitmask
+#define FL_IOPL_0       0x00000000  //   IOPL == 0
+#define FL_IOPL_1       0x00001000  //   IOPL == 1
+#define FL_IOPL_2       0x00002000  //   IOPL == 2
+#define FL_IOPL_3       0x00003000  //   IOPL == 3
+#define FL_NT           0x00004000  // Nested Task
+#define FL_RF           0x00010000  // Resume Flag
+#define FL_VM           0x00020000  // Virtual 8086 mode
+#define FL_AC           0x00040000  // Alignment Check
+#define FL_VIF          0x00080000  // Virtual Interrupt Flag
+#define FL_VIP          0x00100000  // Virtual Interrupt Pending
+#define FL_ID           0x00200000  // ID flag
+
+/* Application segment type bits */
+#define STA_X           0x8         // Executable segment
+#define STA_E           0x4         // Expand down (non-executable segments)
+#define STA_C           0x4         // Conforming code segment (executable only)
+#define STA_W           0x2         // Writeable (non-executable segments)
+#define STA_R           0x2         // Readable (executable segments)
+#define STA_A           0x1         // Accessed
+
+/* System segment type bits */
+#define STS_T16A        0x1         // Available 16-bit TSS
+#define STS_LDT         0x2         // Local Descriptor Table
+#define STS_T16B        0x3         // Busy 16-bit TSS
+#define STS_CG16        0x4         // 16-bit Call Gate
+#define STS_TG          0x5         // Task Gate / Coum Transmitions
+#define STS_IG16        0x6         // 16-bit Interrupt Gate
+#define STS_TG16        0x7         // 16-bit Trap Gate
+#define STS_T32A        0x9         // Available 32-bit TSS
+#define STS_T32B        0xB         // Busy 32-bit TSS
+#define STS_CG32        0xC         // 32-bit Call Gate
+#define STS_IG32        0xE         // 32-bit Interrupt Gate
+#define STS_TG32        0xF         // 32-bit Trap Gate
+
+#ifdef __ASSEMBLER__
+
+#define SEG_NULL                                                \
+    .word 0, 0;                                                 \
+    .byte 0, 0, 0, 0
+
+#define SEG_ASM(type,base,lim)                                  \
+    .word (((lim) >> 12) & 0xffff), ((base) & 0xffff);          \
+    .byte (((base) >> 16) & 0xff), (0x90 | (type)),             \
+        (0xC0 | (((lim) >> 28) & 0xf)), (((base) >> 24) & 0xff)
+
+#else /* not __ASSEMBLER__ */
+
+#include <defs.h>
+
+/* Gate descriptors for interrupts and traps */
+struct gatedesc {
+    unsigned gd_off_15_0 : 16;      // low 16 bits of offset in segment
+    unsigned gd_ss : 16;            // segment selector
+    unsigned gd_args : 5;           // # args, 0 for interrupt/trap gates
+    unsigned gd_rsv1 : 3;           // reserved(should be zero I guess)
+    unsigned gd_type : 4;           // type(STS_{TG,IG32,TG32})
+    unsigned gd_s : 1;              // must be 0 (system)
+    unsigned gd_dpl : 2;            // descriptor(meaning new) privilege level
+    unsigned gd_p : 1;              // Present
+    unsigned gd_off_31_16 : 16;     // high bits of offset in segment
+};
+
+/* *
+ * Set up a normal interrupt/trap gate descriptor
+ *   - istrap: 1 for a trap (= exception) gate, 0 for an interrupt gate
+ *   - sel: Code segment selector for interrupt/trap handler
+ *   - off: Offset in code segment for interrupt/trap handler
+ *   - dpl: Descriptor Privilege Level - the privilege level required
+ *          for software to invoke this interrupt/trap gate explicitly
+ *          using an int instruction.
+ * */
+#define SETGATE(gate, istrap, sel, off, dpl) {               \
+        (gate).gd_off_15_0 = (uint32_t)(off) & 0xffff;      \
+        (gate).gd_ss = (sel);                                \
+        (gate).gd_args = 0;                                 \
+        (gate).gd_rsv1 = 0;                                 \
+        (gate).gd_type = (istrap) ? STS_TG32 : STS_IG32;    \
+        (gate).gd_s = 0;                                    \
+        (gate).gd_dpl = (dpl);                              \
+        (gate).gd_p = 1;                                    \
+        (gate).gd_off_31_16 = (uint32_t)(off) >> 16;        \
+    }
+
+/* Set up a call gate descriptor */
+#define SETCALLGATE(gate, ss, off, dpl) {                   \
+        (gate).gd_off_15_0 = (uint32_t)(off) & 0xffff;      \
+        (gate).gd_ss = (ss);                                \
+        (gate).gd_args = 0;                                 \
+        (gate).gd_rsv1 = 0;                                 \
+        (gate).gd_type = STS_CG32;                          \
+        (gate).gd_s = 0;                                    \
+        (gate).gd_dpl = (dpl);                              \
+        (gate).gd_p = 1;                                    \
+        (gate).gd_off_31_16 = (uint32_t)(off) >> 16;        \
+    }
+
+/* segment descriptors */
+struct segdesc {
+    unsigned sd_lim_15_0 : 16;      // low bits of segment limit
+    unsigned sd_base_15_0 : 16;     // low bits of segment base address
+    unsigned sd_base_23_16 : 8;     // middle bits of segment base address
+    unsigned sd_type : 4;           // segment type (see STS_ constants)
+    unsigned sd_s : 1;              // 0 = system, 1 = application
+    unsigned sd_dpl : 2;            // descriptor Privilege Level
+    unsigned sd_p : 1;              // present
+    unsigned sd_lim_19_16 : 4;      // high bits of segment limit
+    unsigned sd_avl : 1;            // unused (available for software use)
+    unsigned sd_rsv1 : 1;           // reserved
+    unsigned sd_db : 1;             // 0 = 16-bit segment, 1 = 32-bit segment
+    unsigned sd_g : 1;              // granularity: limit scaled by 4K when set
+    unsigned sd_base_31_24 : 8;     // high bits of segment base address
+};
+
+#define SEG_NULL                                            \
+    (struct segdesc) {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
+
+#define SEG(type, base, lim, dpl)                           \
+    (struct segdesc) {                                      \
+        ((lim) >> 12) & 0xffff, (base) & 0xffff,            \
+        ((base) >> 16) & 0xff, type, 1, dpl, 1,             \
+        (unsigned)(lim) >> 28, 0, 0, 1, 1,                  \
+        (unsigned) (base) >> 24                             \
+    }
+
+#define SEGTSS(type, base, lim, dpl)                        \
+    (struct segdesc) {                                      \
+        (lim) & 0xffff, (base) & 0xffff,                    \
+        ((base) >> 16) & 0xff, type, 0, dpl, 1,             \
+        (unsigned) (lim) >> 16, 0, 0, 1, 0,                 \
+        (unsigned) (base) >> 24                             \
+    }
+
+/* task state segment format (as described by the Pentium architecture book) */
+struct taskstate {
+    uint32_t ts_link;       // old ts selector
+    uintptr_t ts_esp0;      // stack pointers and segment selectors
+    uint16_t ts_ss0;        // after an increase in privilege level
+    uint16_t ts_padding1;
+    uintptr_t ts_esp1;
+    uint16_t ts_ss1;
+    uint16_t ts_padding2;
+    uintptr_t ts_esp2;
+    uint16_t ts_ss2;
+    uint16_t ts_padding3;
+    uintptr_t ts_cr3;       // page directory base
+    uintptr_t ts_eip;       // saved state from last task switch
+    uint32_t ts_eflags;
+    uint32_t ts_eax;        // more saved state (registers)
+    uint32_t ts_ecx;
+    uint32_t ts_edx;
+    uint32_t ts_ebx;
+    uintptr_t ts_esp;
+    uintptr_t ts_ebp;
+    uint32_t ts_esi;
+    uint32_t ts_edi;
+    uint16_t ts_es;         // even more saved state (segment selectors)
+    uint16_t ts_padding4;
+    uint16_t ts_cs;
+    uint16_t ts_padding5;
+    uint16_t ts_ss;
+    uint16_t ts_padding6;
+    uint16_t ts_ds;
+    uint16_t ts_padding7;
+    uint16_t ts_fs;
+    uint16_t ts_padding8;
+    uint16_t ts_gs;
+    uint16_t ts_padding9;
+    uint16_t ts_ldt;
+    uint16_t ts_padding10;
+    uint16_t ts_t;          // trap on task switch
+    uint16_t ts_iomb;       // i/o map base address
+} __attribute__((packed));
+
+#endif /* !__ASSEMBLER__ */
+
+// A linear address 'la' has a three-part structure as follows:
+//
+// +--------10------+-------10-------+---------12----------+
+// | Page Directory |   Page Table   | Offset within Page  |
+// |      Index     |     Index      |                     |
+// +----------------+----------------+---------------------+
+//  \--- PDX(la) --/ \--- PTX(la) --/ \---- PGOFF(la) ----/
+//  \----------- PPN(la) -----------/
+//
+// The PDX, PTX, PGOFF, and PPN macros decompose linear addresses as shown.
+// To construct a linear address la from PDX(la), PTX(la), and PGOFF(la),
+// use PGADDR(PDX(la), PTX(la), PGOFF(la)).
+
+// page directory index
+#define PDX(la) ((((uintptr_t)(la)) >> PDXSHIFT) & 0x3FF)
+
+// page table index
+#define PTX(la) ((((uintptr_t)(la)) >> PTXSHIFT) & 0x3FF)
+
+// page number field of address
+#define PPN(la) (((uintptr_t)(la)) >> PTXSHIFT)
+
+// offset in page
+#define PGOFF(la) (((uintptr_t)(la)) & 0xFFF)
+
+// construct linear address from indexes and offset
+#define PGADDR(d, t, o) ((uintptr_t)((d) << PDXSHIFT | (t) << PTXSHIFT | (o)))
+
+// address in page table or page directory entry
+#define PTE_ADDR(pte)   ((uintptr_t)(pte) & ~0xFFF)
+#define PDE_ADDR(pde)   PTE_ADDR(pde)
+
+/* page directory and page table constants */
+#define NPDEENTRY       1024                    // page directory entries per page directory
+#define NPTEENTRY       1024                    // page table entries per page table
+
+#define PGSIZE          4096                    // bytes mapped by a page
+#define PGSHIFT         12                      // log2(PGSIZE)
+#define PTSIZE          (PGSIZE * NPTEENTRY)    // bytes mapped by a page directory entry
+#define PTSHIFT         22                      // log2(PTSIZE)
+
+#define PTXSHIFT        12                      // offset of PTX in a linear address
+#define PDXSHIFT        22                      // offset of PDX in a linear address
+
+/* page table/directory entry flags */
+#define PTE_P           0x001                   // Present
+#define PTE_W           0x002                   // Writeable
+#define PTE_U           0x004                   // User
+#define PTE_PWT         0x008                   // Write-Through
+#define PTE_PCD         0x010                   // Cache-Disable
+#define PTE_A           0x020                   // Accessed
+#define PTE_D           0x040                   // Dirty
+#define PTE_PS          0x080                   // Page Size
+#define PTE_MBZ         0x180                   // Bits must be zero
+#define PTE_AVAIL       0xE00                   // Available for software use
+                                                // The PTE_AVAIL bits aren't used by the kernel or interpreted by the
+                                                // hardware, so user processes are allowed to set them arbitrarily.
+
+#define PTE_USER        (PTE_U | PTE_W | PTE_P)
+
+/* Control Register flags */
+#define CR0_PE          0x00000001              // Protection Enable
+#define CR0_MP          0x00000002              // Monitor coProcessor
+#define CR0_EM          0x00000004              // Emulation
+#define CR0_TS          0x00000008              // Task Switched
+#define CR0_ET          0x00000010              // Extension Type
+#define CR0_NE          0x00000020              // Numeric Errror
+#define CR0_WP          0x00010000              // Write Protect
+#define CR0_AM          0x00040000              // Alignment Mask
+#define CR0_NW          0x20000000              // Not Writethrough
+#define CR0_CD          0x40000000              // Cache Disable
+#define CR0_PG          0x80000000              // Paging
+
+#define CR4_PCE         0x00000100              // Performance counter enable
+#define CR4_MCE         0x00000040              // Machine Check Enable
+#define CR4_PSE         0x00000010              // Page Size Extensions
+#define CR4_DE          0x00000008              // Debugging Extensions
+#define CR4_TSD         0x00000004              // Time Stamp Disable
+#define CR4_PVI         0x00000002              // Protected-Mode Virtual Interrupts
+#define CR4_VME         0x00000001              // V86 Mode Extensions
+
+#endif /* !__KERN_MM_MMU_H__ */
+

labcodes_answer/lab2_result/kern/mm/pmm.c

@@ -0,0 +1,647 @@
+#include <defs.h>
+#include <x86.h>
+#include <stdio.h>
+#include <string.h>
+#include <mmu.h>
+#include <memlayout.h>
+#include <pmm.h>
+#include <default_pmm.h>
+#include <sync.h>
+#include <error.h>
+
+/* *
+ * Task State Segment:
+ *
+ * The TSS may reside anywhere in memory. A special segment register called
+ * the Task Register (TR) holds a segment selector that points a valid TSS
+ * segment descriptor which resides in the GDT. Therefore, to use a TSS
+ * the following must be done in function gdt_init:
+ *   - create a TSS descriptor entry in GDT
+ *   - add enough information to the TSS in memory as needed
+ *   - load the TR register with a segment selector for that segment
+ *
+ * There are several fileds in TSS for specifying the new stack pointer when a
+ * privilege level change happens. But only the fields SS0 and ESP0 are useful
+ * in our os kernel.
+ *
+ * The field SS0 contains the stack segment selector for CPL = 0, and the ESP0
+ * contains the new ESP value for CPL = 0. When an interrupt happens in protected
+ * mode, the x86 CPU will look in the TSS for SS0 and ESP0 and load their value
+ * into SS and ESP respectively.
+ * */
+static struct taskstate ts = {0};
+
+// virtual address of physicall page array
+struct Page *pages;
+// amount of physical memory (in pages)
+size_t npage = 0;
+
+// virtual address of boot-time page directory
+pde_t *boot_pgdir = NULL;
+// physical address of boot-time page directory
+uintptr_t boot_cr3;
+
+// physical memory management
+const struct pmm_manager *pmm_manager;
+
+/* *
+ * The page directory entry corresponding to the virtual address range
+ * [VPT, VPT + PTSIZE) points to the page directory itself. Thus, the page
+ * directory is treated as a page table as well as a page directory.
+ *
+ * One result of treating the page directory as a page table is that all PTEs
+ * can be accessed though a "virtual page table" at virtual address VPT. And the
+ * PTE for number n is stored in vpt[n].
+ *
+ * A second consequence is that the contents of the current page directory will
+ * always available at virtual address PGADDR(PDX(VPT), PDX(VPT), 0), to which
+ * vpd is set bellow.
+ * */
+pte_t * const vpt = (pte_t *)VPT;
+pde_t * const vpd = (pde_t *)PGADDR(PDX(VPT), PDX(VPT), 0);
+
+/* *
+ * Global Descriptor Table:
+ *
+ * The kernel and user segments are identical (except for the DPL). To load
+ * the %ss register, the CPL must equal the DPL. Thus, we must duplicate the
+ * segments for the user and the kernel. Defined as follows:
+ *   - 0x0 :  unused (always faults -- for trapping NULL far pointers)
+ *   - 0x8 :  kernel code segment
+ *   - 0x10:  kernel data segment
+ *   - 0x18:  user code segment
+ *   - 0x20:  user data segment
+ *   - 0x28:  defined for tss, initialized in gdt_init
+ * */
+static struct segdesc gdt[] = {
+    SEG_NULL,
+    [SEG_KTEXT] = SEG(STA_X | STA_R, 0x0, 0xFFFFFFFF, DPL_KERNEL),
+    [SEG_KDATA] = SEG(STA_W, 0x0, 0xFFFFFFFF, DPL_KERNEL),
+    [SEG_UTEXT] = SEG(STA_X | STA_R, 0x0, 0xFFFFFFFF, DPL_USER),
+    [SEG_UDATA] = SEG(STA_W, 0x0, 0xFFFFFFFF, DPL_USER),
+    [SEG_TSS]   = SEG_NULL,
+};
+
+static struct pseudodesc gdt_pd = {
+    sizeof(gdt) - 1, (uintptr_t)gdt
+};
+
+static void check_alloc_page(void);
+static void check_pgdir(void);
+static void check_boot_pgdir(void);
+
+/* *
+ * lgdt - load the global descriptor table register and reset the
+ * data/code segement registers for kernel.
+ * */
+static inline void
+lgdt(struct pseudodesc *pd) {
+    asm volatile ("lgdt (%0)" :: "r" (pd));
+    asm volatile ("movw %%ax, %%gs" :: "a" (USER_DS));
+    asm volatile ("movw %%ax, %%fs" :: "a" (USER_DS));
+    asm volatile ("movw %%ax, %%es" :: "a" (KERNEL_DS));
+    asm volatile ("movw %%ax, %%ds" :: "a" (KERNEL_DS));
+    asm volatile ("movw %%ax, %%ss" :: "a" (KERNEL_DS));
+    // reload cs
+    asm volatile ("ljmp %0, $1f\n 1:\n" :: "i" (KERNEL_CS));
+}
+
+/* *
+ * load_esp0 - change the ESP0 in default task state segment,
+ * so that we can use different kernel stack when we trap frame
+ * user to kernel.
+ * */
+void
+load_esp0(uintptr_t esp0) {
+    ts.ts_esp0 = esp0;
+}
+
+/* gdt_init - initialize the default GDT and TSS */
+static void
+gdt_init(void) {
+    // set boot kernel stack and default SS0
+    load_esp0((uintptr_t)bootstacktop);
+    ts.ts_ss0 = KERNEL_DS;
+
+    // initialize the TSS filed of the gdt
+    gdt[SEG_TSS] = SEGTSS(STS_T32A, (uintptr_t)&ts, sizeof(ts), DPL_KERNEL);
+
+    // reload all segment registers
+    lgdt(&gdt_pd);
+
+    // load the TSS
+    ltr(GD_TSS);
+}
+
+//init_pmm_manager - initialize a pmm_manager instance
+static void
+init_pmm_manager(void) {
+    pmm_manager = &default_pmm_manager;
+    cprintf("memory management: %s\n", pmm_manager->name);
+    pmm_manager->init();
+}
+
+//init_memmap - call pmm->init_memmap to build Page struct for free memory  
+static void
+init_memmap(struct Page *base, size_t n) {
+    pmm_manager->init_memmap(base, n);
+}
+
+//alloc_pages - call pmm->alloc_pages to allocate a continuous n*PAGESIZE memory 
+struct Page *
+alloc_pages(size_t n) {
+    struct Page *page=NULL;
+    bool intr_flag;
+    local_intr_save(intr_flag);
+    {
+        page = pmm_manager->alloc_pages(n);
+    }
+    local_intr_restore(intr_flag);
+    return page;
+}
+
+//free_pages - call pmm->free_pages to free a continuous n*PAGESIZE memory 
+void
+free_pages(struct Page *base, size_t n) {
+    bool intr_flag;
+    local_intr_save(intr_flag);
+    {
+        pmm_manager->free_pages(base, n);
+    }
+    local_intr_restore(intr_flag);
+}
+
+//nr_free_pages - call pmm->nr_free_pages to get the size (nr*PAGESIZE) 
+//of current free memory
+size_t
+nr_free_pages(void) {
+    size_t ret;
+    bool intr_flag;
+    local_intr_save(intr_flag);
+    {
+        ret = pmm_manager->nr_free_pages();
+    }
+    local_intr_restore(intr_flag);
+    return ret;
+}
+
+/* pmm_init - initialize the physical memory management */
+static void
+page_init(void) {
+    struct e820map *memmap = (struct e820map *)(0x8000 + KERNBASE);
+    uint64_t maxpa = 0;
+
+    cprintf("e820map:\n");
+    int i;
+    for (i = 0; i < memmap->nr_map; i ++) {
+        uint64_t begin = memmap->map[i].addr, end = begin + memmap->map[i].size;
+        cprintf("  memory: %08llx, [%08llx, %08llx], type = %d.\n",
+                memmap->map[i].size, begin, end - 1, memmap->map[i].type);
+        if (memmap->map[i].type == E820_ARM) {
+            if (maxpa < end && begin < KMEMSIZE) {
+                maxpa = end;
+            }
+        }
+    }
+    if (maxpa > KMEMSIZE) {
+        maxpa = KMEMSIZE;
+    }
+
+    extern char end[];
+
+    npage = maxpa / PGSIZE;
+    pages = (struct Page *)ROUNDUP((void *)end, PGSIZE);
+
+    for (i = 0; i < npage; i ++) {
+        SetPageReserved(pages + i);
+    }
+
+    uintptr_t freemem = PADDR((uintptr_t)pages + sizeof(struct Page) * npage);
+
+    for (i = 0; i < memmap->nr_map; i ++) {
+        uint64_t begin = memmap->map[i].addr, end = begin + memmap->map[i].size;
+        if (memmap->map[i].type == E820_ARM) {
+            if (begin < freemem) {
+                begin = freemem;
+            }
+            if (end > KMEMSIZE) {
+                end = KMEMSIZE;
+            }
+            if (begin < end) {
+                begin = ROUNDUP(begin, PGSIZE);
+                end = ROUNDDOWN(end, PGSIZE);
+                if (begin < end) {
+                    init_memmap(pa2page(begin), (end - begin) / PGSIZE);
+                }
+            }
+        }
+    }
+}
+
+static void
+enable_paging(void) {
+    lcr3(boot_cr3);
+
+    // turn on paging
+    uint32_t cr0 = rcr0();
+    cr0 |= CR0_PE | CR0_PG | CR0_AM | CR0_WP | CR0_NE | CR0_TS | CR0_EM | CR0_MP;
+    cr0 &= ~(CR0_TS | CR0_EM);
+    lcr0(cr0);
+}
+
+//boot_map_segment - setup&enable the paging mechanism
+// parameters
+//  la:   linear address of this memory need to map (after x86 segment map)
+//  size: memory size
+//  pa:   physical address of this memory
+//  perm: permission of this memory  
+static void
+boot_map_segment(pde_t *pgdir, uintptr_t la, size_t size, uintptr_t pa, uint32_t perm) {
+    assert(PGOFF(la) == PGOFF(pa));
+    size_t n = ROUNDUP(size + PGOFF(la), PGSIZE) / PGSIZE;
+    la = ROUNDDOWN(la, PGSIZE);
+    pa = ROUNDDOWN(pa, PGSIZE);
+    for (; n > 0; n --, la += PGSIZE, pa += PGSIZE) {
+        pte_t *ptep = get_pte(pgdir, la, 1);
+        assert(ptep != NULL);
+        *ptep = pa | PTE_P | perm;
+    }
+}
+
+//boot_alloc_page - allocate one page using pmm->alloc_pages(1) 
+// return value: the kernel virtual address of this allocated page
+//note: this function is used to get the memory for PDT(Page Directory Table)&PT(Page Table)
+static void *
+boot_alloc_page(void) {
+    struct Page *p = alloc_page();
+    if (p == NULL) {
+        panic("boot_alloc_page failed.\n");
+    }
+    return page2kva(p);
+}
+
+//pmm_init - setup a pmm to manage physical memory, build PDT&PT to setup paging mechanism 
+//         - check the correctness of pmm & paging mechanism, print PDT&PT
+void
+pmm_init(void) {
+    //We need to alloc/free the physical memory (granularity is 4KB or other size). 
+    //So a framework of physical memory manager (struct pmm_manager)is defined in pmm.h
+    //First we should init a physical memory manager(pmm) based on the framework.
+    //Then pmm can alloc/free the physical memory. 
+    //Now the first_fit/best_fit/worst_fit/buddy_system pmm are available.
+    init_pmm_manager();
+
+    // detect physical memory space, reserve already used memory,
+    // then use pmm->init_memmap to create free page list
+    page_init();
+
+    //use pmm->check to verify the correctness of the alloc/free function in a pmm
+    check_alloc_page();
+
+    // create boot_pgdir, an initial page directory(Page Directory Table, PDT)
+    boot_pgdir = boot_alloc_page();
+    memset(boot_pgdir, 0, PGSIZE);
+    boot_cr3 = PADDR(boot_pgdir);
+
+    check_pgdir();
+
+    static_assert(KERNBASE % PTSIZE == 0 && KERNTOP % PTSIZE == 0);
+
+    // recursively insert boot_pgdir in itself
+    // to form a virtual page table at virtual address VPT
+    boot_pgdir[PDX(VPT)] = PADDR(boot_pgdir) | PTE_P | PTE_W;
+
+    // map all physical memory to linear memory with base linear addr KERNBASE
+    //linear_addr KERNBASE~KERNBASE+KMEMSIZE = phy_addr 0~KMEMSIZE
+    //But shouldn't use this map until enable_paging() & gdt_init() finished.
+    boot_map_segment(boot_pgdir, KERNBASE, KMEMSIZE, 0, PTE_W);
+
+    //temporary map: 
+    //virtual_addr 3G~3G+4M = linear_addr 0~4M = linear_addr 3G~3G+4M = phy_addr 0~4M     
+    boot_pgdir[0] = boot_pgdir[PDX(KERNBASE)];
+
+    enable_paging();
+
+    //reload gdt(third time,the last time) to map all physical memory
+    //virtual_addr 0~4G=liear_addr 0~4G
+    //then set kernel stack(ss:esp) in TSS, setup TSS in gdt, load TSS
+    gdt_init();
+
+    //disable the map of virtual_addr 0~4M
+    boot_pgdir[0] = 0;
+
+    //now the basic virtual memory map(see memalyout.h) is established.
+    //check the correctness of the basic virtual memory map.
+    check_boot_pgdir();
+
+    print_pgdir();
+
+}
+
+//get_pte - get pte and return the kernel virtual address of this pte for la
+//        - if the PT contians this pte didn't exist, alloc a page for PT
+// parameter:
+//  pgdir:  the kernel virtual base address of PDT
+//  la:     the linear address need to map
+//  create: a logical value to decide if alloc a page for PT
+// return vaule: the kernel virtual address of this pte
+pte_t *
+get_pte(pde_t *pgdir, uintptr_t la, bool create) {
+    /* LAB2 EXERCISE 2: YOUR CODE
+     *
+     * If you need to visit a physical address, please use KADDR()
+     * please read pmm.h for useful macros
+     *
+     * Maybe you want help comment, BELOW comments can help you finish the code
+     *
+     * Some Useful MACROs and DEFINEs, you can use them in below implementation.
+     * MACROs or Functions:
+     *   PDX(la) = the index of page directory entry of VIRTUAL ADDRESS la.
+     *   KADDR(pa) : takes a physical address and returns the corresponding kernel virtual address.
+     *   set_page_ref(page,1) : means the page be referenced by one time
+     *   page2pa(page): get the physical address of memory which this (struct Page *) page  manages
+     *   struct Page * alloc_page() : allocation a page
+     *   memset(void *s, char c, size_t n) : sets the first n bytes of the memory area pointed by s
+     *                                       to the specified value c.
+     * DEFINEs:
+     *   PTE_P           0x001                   // page table/directory entry flags bit : Present
+     *   PTE_W           0x002                   // page table/directory entry flags bit : Writeable
+     *   PTE_U           0x004                   // page table/directory entry flags bit : User can access
+     */
+#if 0
+    pde_t *pdep = NULL;   // (1) find page directory entry
+    if (0) {              // (2) check if entry is not present
+                          // (3) check if creating is needed, then alloc page for page table
+                          // CAUTION: this page is used for page table, not for common data page
+                          // (4) set page reference
+        uintptr_t pa = 0; // (5) get linear address of page
+                          // (6) clear page content using memset
+                          // (7) set page directory entry's permission
+    }
+    return NULL;          // (8) return page table entry
+#endif
+    pde_t *pdep = &pgdir[PDX(la)];
+    if (!(*pdep & PTE_P)) {
+        struct Page *page;
+        if (!create || (page = alloc_page()) == NULL) {
+            return NULL;
+        }
+        set_page_ref(page, 1);
+        uintptr_t pa = page2pa(page);
+        memset(KADDR(pa), 0, PGSIZE);
+        *pdep = pa | PTE_U | PTE_W | PTE_P;
+    }
+    return &((pte_t *)KADDR(PDE_ADDR(*pdep)))[PTX(la)];
+}
+
+//get_page - get related Page struct for linear address la using PDT pgdir
+struct Page *
+get_page(pde_t *pgdir, uintptr_t la, pte_t **ptep_store) {
+    pte_t *ptep = get_pte(pgdir, la, 0);
+    if (ptep_store != NULL) {
+        *ptep_store = ptep;
+    }
+    if (ptep != NULL && *ptep & PTE_P) {
+        return pa2page(*ptep);
+    }
+    return NULL;
+}
+
+//page_remove_pte - free an Page sturct which is related linear address la
+//                - and clean(invalidate) pte which is related linear address la
+//note: PT is changed, so the TLB need to be invalidate 
+static inline void
+page_remove_pte(pde_t *pgdir, uintptr_t la, pte_t *ptep) {
+    /* LAB2 EXERCISE 3: YOUR CODE
+     *
+     * Please check if ptep is valid, and tlb must be manually updated if mapping is updated
+     *
+     * Maybe you want help comment, BELOW comments can help you finish the code
+     *
+     * Some Useful MACROs and DEFINEs, you can use them in below implementation.
+     * MACROs or Functions:
+     *   struct Page *page pte2page(*ptep): get the according page from the value of a ptep
+     *   free_page : free a page
+     *   page_ref_dec(page) : decrease page->ref. NOTICE: ff page->ref == 0 , then this page should be free.
+     *   tlb_invalidate(pde_t *pgdir, uintptr_t la) : Invalidate a TLB entry, but only if the page tables being
+     *                        edited are the ones currently in use by the processor.
+     * DEFINEs:
+     *   PTE_P           0x001                   // page table/directory entry flags bit : Present
+     */
+#if 0
+    if (0) {                      //(1) check if page directory is present
+        struct Page *page = NULL; //(2) find corresponding page to pte
+                                  //(3) decrease page reference
+                                  //(4) and free this page when page reference reachs 0
+                                  //(5) clear second page table entry
+                                  //(6) flush tlb
+    }
+#endif
+    if (*ptep & PTE_P) {
+        struct Page *page = pte2page(*ptep);
+        if (page_ref_dec(page) == 0) {
+            free_page(page);
+        }
+        *ptep = 0;
+        tlb_invalidate(pgdir, la);
+    }
+}
+
+//page_remove - free an Page which is related linear address la and has an validated pte
+void
+page_remove(pde_t *pgdir, uintptr_t la) {
+    pte_t *ptep = get_pte(pgdir, la, 0);
+    if (ptep != NULL) {
+        page_remove_pte(pgdir, la, ptep);
+    }
+}
+
+//page_insert - build the map of phy addr of an Page with the linear addr la
+// paramemters:
+//  pgdir: the kernel virtual base address of PDT
+//  page:  the Page which need to map
+//  la:    the linear address need to map
+//  perm:  the permission of this Page which is setted in related pte
+// return value: always 0
+//note: PT is changed, so the TLB need to be invalidate 
+int
+page_insert(pde_t *pgdir, struct Page *page, uintptr_t la, uint32_t perm) {
+    pte_t *ptep = get_pte(pgdir, la, 1);
+    if (ptep == NULL) {
+        return -E_NO_MEM;
+    }
+    page_ref_inc(page);
+    if (*ptep & PTE_P) {
+        struct Page *p = pte2page(*ptep);
+        if (p == page) {
+            page_ref_dec(page);
+        }
+        else {
+            page_remove_pte(pgdir, la, ptep);
+        }
+    }
+    *ptep = page2pa(page) | PTE_P | perm;
+    tlb_invalidate(pgdir, la);
+    return 0;
+}
+
+// invalidate a TLB entry, but only if the page tables being
+// edited are the ones currently in use by the processor.
+void
+tlb_invalidate(pde_t *pgdir, uintptr_t la) {
+    if (rcr3() == PADDR(pgdir)) {
+        invlpg((void *)la);
+    }
+}
+
+static void
+check_alloc_page(void) {
+    pmm_manager->check();
+    cprintf("check_alloc_page() succeeded!\n");
+}
+
+static void
+check_pgdir(void) {
+    assert(npage <= KMEMSIZE / PGSIZE);
+    assert(boot_pgdir != NULL && (uint32_t)PGOFF(boot_pgdir) == 0);
+    assert(get_page(boot_pgdir, 0x0, NULL) == NULL);
+
+    struct Page *p1, *p2;
+    p1 = alloc_page();
+    assert(page_insert(boot_pgdir, p1, 0x0, 0) == 0);
+
+    pte_t *ptep;
+    assert((ptep = get_pte(boot_pgdir, 0x0, 0)) != NULL);
+    assert(pa2page(*ptep) == p1);
+    assert(page_ref(p1) == 1);
+
+    ptep = &((pte_t *)KADDR(PDE_ADDR(boot_pgdir[0])))[1];
+    assert(get_pte(boot_pgdir, PGSIZE, 0) == ptep);
+
+    p2 = alloc_page();
+    assert(page_insert(boot_pgdir, p2, PGSIZE, PTE_U | PTE_W) == 0);
+    assert((ptep = get_pte(boot_pgdir, PGSIZE, 0)) != NULL);
+    assert(*ptep & PTE_U);
+    assert(*ptep & PTE_W);
+    assert(boot_pgdir[0] & PTE_U);
+    assert(page_ref(p2) == 1);
+
+    assert(page_insert(boot_pgdir, p1, PGSIZE, 0) == 0);
+    assert(page_ref(p1) == 2);
+    assert(page_ref(p2) == 0);
+    assert((ptep = get_pte(boot_pgdir, PGSIZE, 0)) != NULL);
+    assert(pa2page(*ptep) == p1);
+    assert((*ptep & PTE_U) == 0);
+
+    page_remove(boot_pgdir, 0x0);
+    assert(page_ref(p1) == 1);
+    assert(page_ref(p2) == 0);
+
+    page_remove(boot_pgdir, PGSIZE);
+    assert(page_ref(p1) == 0);
+    assert(page_ref(p2) == 0);
+
+    assert(page_ref(pa2page(boot_pgdir[0])) == 1);
+    free_page(pa2page(boot_pgdir[0]));
+    boot_pgdir[0] = 0;
+
+    cprintf("check_pgdir() succeeded!\n");
+}
+
+static void
+check_boot_pgdir(void) {
+    pte_t *ptep;
+    int i;
+    for (i = 0; i < npage; i += PGSIZE) {
+        assert((ptep = get_pte(boot_pgdir, (uintptr_t)KADDR(i), 0)) != NULL);
+        assert(PTE_ADDR(*ptep) == i);
+    }
+
+    assert(PDE_ADDR(boot_pgdir[PDX(VPT)]) == PADDR(boot_pgdir));
+
+    assert(boot_pgdir[0] == 0);
+
+    struct Page *p;
+    p = alloc_page();
+    assert(page_insert(boot_pgdir, p, 0x100, PTE_W) == 0);
+    assert(page_ref(p) == 1);
+    assert(page_insert(boot_pgdir, p, 0x100 + PGSIZE, PTE_W) == 0);
+    assert(page_ref(p) == 2);
+
+    const char *str = "ucore: Hello world!!";
+    strcpy((void *)0x100, str);
+    assert(strcmp((void *)0x100, (void *)(0x100 + PGSIZE)) == 0);
+
+    *(char *)(page2kva(p) + 0x100) = '\0';
+    assert(strlen((const char *)0x100) == 0);
+
+    free_page(p);
+    free_page(pa2page(PDE_ADDR(boot_pgdir[0])));
+    boot_pgdir[0] = 0;
+
+    cprintf("check_boot_pgdir() succeeded!\n");
+}
+
+//perm2str - use string 'u,r,w,-' to present the permission
+static const char *
+perm2str(int perm) {
+    static char str[4];
+    str[0] = (perm & PTE_U) ? 'u' : '-';
+    str[1] = 'r';
+    str[2] = (perm & PTE_W) ? 'w' : '-';
+    str[3] = '\0';
+    return str;
+}
+
+//get_pgtable_items - In [left, right] range of PDT or PT, find a continuous linear addr space
+//                  - (left_store*X_SIZE~right_store*X_SIZE) for PDT or PT
+//                  - X_SIZE=PTSIZE=4M, if PDT; X_SIZE=PGSIZE=4K, if PT
+// paramemters:
+//  left:        no use ???
+//  right:       the high side of table's range
+//  start:       the low side of table's range
+//  table:       the beginning addr of table
+//  left_store:  the pointer of the high side of table's next range
+//  right_store: the pointer of the low side of table's next range
+// return value: 0 - not a invalid item range, perm - a valid item range with perm permission 
+static int
+get_pgtable_items(size_t left, size_t right, size_t start, uintptr_t *table, size_t *left_store, size_t *right_store) {
+    if (start >= right) {
+        return 0;
+    }
+    while (start < right && !(table[start] & PTE_P)) {
+        start ++;
+    }
+    if (start < right) {
+        if (left_store != NULL) {
+            *left_store = start;
+        }
+        int perm = (table[start ++] & PTE_USER);
+        while (start < right && (table[start] & PTE_USER) == perm) {
+            start ++;
+        }
+        if (right_store != NULL) {
+            *right_store = start;
+        }
+        return perm;
+    }
+    return 0;
+}
+
+//print_pgdir - print the PDT&PT
+void
+print_pgdir(void) {
+    cprintf("-------------------- BEGIN --------------------\n");
+    size_t left, right = 0, perm;
+    while ((perm = get_pgtable_items(0, NPDEENTRY, right, vpd, &left, &right)) != 0) {
+        cprintf("PDE(%03x) %08x-%08x %08x %s\n", right - left,
+                left * PTSIZE, right * PTSIZE, (right - left) * PTSIZE, perm2str(perm));
+        size_t l, r = left * NPTEENTRY;
+        while ((perm = get_pgtable_items(left * NPTEENTRY, right * NPTEENTRY, r, vpt, &l, &r)) != 0) {
+            cprintf("  |-- PTE(%05x) %08x-%08x %08x %s\n", r - l,
+                    l * PGSIZE, r * PGSIZE, (r - l) * PGSIZE, perm2str(perm));
+        }
+    }
+    cprintf("--------------------- END ---------------------\n");
+}
+

labcodes_answer/lab2_result/kern/mm/pmm.h

@@ -0,0 +1,143 @@
+#ifndef __KERN_MM_PMM_H__
+#define __KERN_MM_PMM_H__
+
+#include <defs.h>
+#include <mmu.h>
+#include <memlayout.h>
+#include <atomic.h>
+#include <assert.h>
+
+// pmm_manager is a physical memory management class. A special pmm manager - XXX_pmm_manager
+// only needs to implement the methods in pmm_manager class, then XXX_pmm_manager can be used
+// by ucore to manage the total physical memory space.
+struct pmm_manager {
+    const char *name;                                 // XXX_pmm_manager's name
+    void (*init)(void);                               // initialize internal description&management data structure
+                                                      // (free block list, number of free block) of XXX_pmm_manager 
+    void (*init_memmap)(struct Page *base, size_t n); // setup description&management data structcure according to
+                                                      // the initial free physical memory space 
+    struct Page *(*alloc_pages)(size_t n);            // allocate >=n pages, depend on the allocation algorithm 
+    void (*free_pages)(struct Page *base, size_t n);  // free >=n pages with "base" addr of Page descriptor structures(memlayout.h)
+    size_t (*nr_free_pages)(void);                    // return the number of free pages 
+    void (*check)(void);                              // check the correctness of XXX_pmm_manager 
+};
+
+extern const struct pmm_manager *pmm_manager;
+extern pde_t *boot_pgdir;
+extern uintptr_t boot_cr3;
+
+void pmm_init(void);
+
+struct Page *alloc_pages(size_t n);
+void free_pages(struct Page *base, size_t n);
+size_t nr_free_pages(void);
+
+#define alloc_page() alloc_pages(1)
+#define free_page(page) free_pages(page, 1)
+
+pte_t *get_pte(pde_t *pgdir, uintptr_t la, bool create);
+struct Page *get_page(pde_t *pgdir, uintptr_t la, pte_t **ptep_store);
+void page_remove(pde_t *pgdir, uintptr_t la);
+int page_insert(pde_t *pgdir, struct Page *page, uintptr_t la, uint32_t perm);
+
+void load_esp0(uintptr_t esp0);
+void tlb_invalidate(pde_t *pgdir, uintptr_t la);
+
+void print_pgdir(void);
+
+/* *
+ * PADDR - takes a kernel virtual address (an address that points above KERNBASE),
+ * where the machine's maximum 256MB of physical memory is mapped and returns the
+ * corresponding physical address.  It panics if you pass it a non-kernel virtual address.
+ * */
+#define PADDR(kva) ({                                                   \
+            uintptr_t __m_kva = (uintptr_t)(kva);                       \
+            if (__m_kva < KERNBASE) {                                   \
+                panic("PADDR called with invalid kva %08lx", __m_kva);  \
+            }                                                           \
+            __m_kva - KERNBASE;                                         \
+        })
+
+/* *
+ * KADDR - takes a physical address and returns the corresponding kernel virtual
+ * address. It panics if you pass an invalid physical address.
+ * */
+#define KADDR(pa) ({                                                    \
+            uintptr_t __m_pa = (pa);                                    \
+            size_t __m_ppn = PPN(__m_pa);                               \
+            if (__m_ppn >= npage) {                                     \
+                panic("KADDR called with invalid pa %08lx", __m_pa);    \
+            }                                                           \
+            (void *) (__m_pa + KERNBASE);                               \
+        })
+
+extern struct Page *pages;
+extern size_t npage;
+
+static inline ppn_t
+page2ppn(struct Page *page) {
+    return page - pages;
+}
+
+static inline uintptr_t
+page2pa(struct Page *page) {
+    return page2ppn(page) << PGSHIFT;
+}
+
+static inline struct Page *
+pa2page(uintptr_t pa) {
+    if (PPN(pa) >= npage) {
+        panic("pa2page called with invalid pa");
+    }
+    return &pages[PPN(pa)];
+}
+
+static inline void *
+page2kva(struct Page *page) {
+    return KADDR(page2pa(page));
+}
+
+static inline struct Page *
+kva2page(void *kva) {
+    return pa2page(PADDR(kva));
+}
+
+static inline struct Page *
+pte2page(pte_t pte) {
+    if (!(pte & PTE_P)) {
+        panic("pte2page called with invalid pte");
+    }
+    return pa2page(PTE_ADDR(pte));
+}
+
+static inline struct Page *
+pde2page(pde_t pde) {
+    return pa2page(PDE_ADDR(pde));
+}
+
+static inline int
+page_ref(struct Page *page) {
+    return page->ref;
+}
+
+static inline void
+set_page_ref(struct Page *page, int val) {
+    page->ref = val;
+}
+
+static inline int
+page_ref_inc(struct Page *page) {
+    page->ref += 1;
+    return page->ref;
+}
+
+static inline int
+page_ref_dec(struct Page *page) {
+    page->ref -= 1;
+    return page->ref;
+}
+
+extern char bootstack[], bootstacktop[];
+
+#endif /* !__KERN_MM_PMM_H__ */
+

labcodes_answer/lab2_result/kern/sync/sync.h

@@ -0,0 +1,28 @@
+#ifndef __KERN_SYNC_SYNC_H__
+#define __KERN_SYNC_SYNC_H__
+
+#include <x86.h>
+#include <intr.h>
+#include <mmu.h>
+
+static inline bool
+__intr_save(void) {
+    if (read_eflags() & FL_IF) {
+        intr_disable();
+        return 1;
+    }
+    return 0;
+}
+
+static inline void
+__intr_restore(bool flag) {
+    if (flag) {
+        intr_enable();
+    }
+}
+
+#define local_intr_save(x)      do { x = __intr_save(); } while (0)
+#define local_intr_restore(x)   __intr_restore(x);
+
+#endif /* !__KERN_SYNC_SYNC_H__ */
+

labcodes_answer/lab2_result/kern/trap/trap.c

@@ -0,0 +1,197 @@
+#include <defs.h>
+#include <mmu.h>
+#include <memlayout.h>
+#include <clock.h>
+#include <trap.h>
+#include <x86.h>
+#include <stdio.h>
+#include <assert.h>
+#include <console.h>
+#include <kdebug.h>
+
+#define TICK_NUM 100
+
+static void print_ticks() {
+    cprintf("%d ticks\n",TICK_NUM);
+#ifdef DEBUG_GRADE
+    cprintf("End of Test.\n");
+    panic("EOT: kernel seems ok.");
+#endif
+}
+
+/* *
+ * Interrupt descriptor table:
+ *
+ * Must be built at run time because shifted function addresses can't
+ * be represented in relocation records.
+ * */
+static struct gatedesc idt[256] = {{0}};
+
+static struct pseudodesc idt_pd = {
+    sizeof(idt) - 1, (uintptr_t)idt
+};
+
+/* idt_init - initialize IDT to each of the entry points in kern/trap/vectors.S */
+void
+idt_init(void) {
+     /* LAB1 YOUR CODE : STEP 2 */
+     /* (1) Where are the entry addrs of each Interrupt Service Routine (ISR)?
+      *     All ISR's entry addrs are stored in __vectors. where is uintptr_t __vectors[] ?
+      *     __vectors[] is in kern/trap/vector.S which is produced by tools/vector.c
+      *     (try "make" command in lab1, then you will find vector.S in kern/trap DIR)
+      *     You can use  "extern uintptr_t __vectors[];" to define this extern variable which will be used later.
+      * (2) Now you should setup the entries of ISR in Interrupt Description Table (IDT).
+      *     Can you see idt[256] in this file? Yes, it's IDT! you can use SETGATE macro to setup each item of IDT
+      * (3) After setup the contents of IDT, you will let CPU know where is the IDT by using 'lidt' instruction.
+      *     You don't know the meaning of this instruction? just google it! and check the libs/x86.h to know more.
+      *     Notice: the argument of lidt is idt_pd. try to find it!
+      */
+    extern uintptr_t __vectors[];
+    int i;
+    for (i = 0; i < sizeof(idt) / sizeof(struct gatedesc); i ++) {
+        SETGATE(idt[i], 0, GD_KTEXT, __vectors[i], DPL_KERNEL);
+    }
+    lidt(&idt_pd);
+}
+
+static const char *
+trapname(int trapno) {
+    static const char * const excnames[] = {
+        "Divide error",
+        "Debug",
+        "Non-Maskable Interrupt",
+        "Breakpoint",
+        "Overflow",
+        "BOUND Range Exceeded",
+        "Invalid Opcode",
+        "Device Not Available",
+        "Double Fault",
+        "Coprocessor Segment Overrun",
+        "Invalid TSS",
+        "Segment Not Present",
+        "Stack Fault",
+        "General Protection",
+        "Page Fault",
+        "(unknown trap)",
+        "x87 FPU Floating-Point Error",
+        "Alignment Check",
+        "Machine-Check",
+        "SIMD Floating-Point Exception"
+    };
+
+    if (trapno < sizeof(excnames)/sizeof(const char * const)) {
+        return excnames[trapno];
+    }
+    if (trapno >= IRQ_OFFSET && trapno < IRQ_OFFSET + 16) {
+        return "Hardware Interrupt";
+    }
+    return "(unknown trap)";
+}
+
+/* trap_in_kernel - test if trap happened in kernel */
+bool
+trap_in_kernel(struct trapframe *tf) {
+    return (tf->tf_cs == (uint16_t)KERNEL_CS);
+}
+
+static const char *IA32flags[] = {
+    "CF", NULL, "PF", NULL, "AF", NULL, "ZF", "SF",
+    "TF", "IF", "DF", "OF", NULL, NULL, "NT", NULL,
+    "RF", "VM", "AC", "VIF", "VIP", "ID", NULL, NULL,
+};
+
+void
+print_trapframe(struct trapframe *tf) {
+    cprintf("trapframe at %p\n", tf);
+    print_regs(&tf->tf_regs);
+    cprintf("  ds   0x----%04x\n", tf->tf_ds);
+    cprintf("  es   0x----%04x\n", tf->tf_es);
+    cprintf("  fs   0x----%04x\n", tf->tf_fs);
+    cprintf("  gs   0x----%04x\n", tf->tf_gs);
+    cprintf("  trap 0x%08x %s\n", tf->tf_trapno, trapname(tf->tf_trapno));
+    cprintf("  err  0x%08x\n", tf->tf_err);
+    cprintf("  eip  0x%08x\n", tf->tf_eip);
+    cprintf("  cs   0x----%04x\n", tf->tf_cs);
+    cprintf("  flag 0x%08x ", tf->tf_eflags);
+
+    int i, j;
+    for (i = 0, j = 1; i < sizeof(IA32flags) / sizeof(IA32flags[0]); i ++, j <<= 1) {
+        if ((tf->tf_eflags & j) && IA32flags[i] != NULL) {
+            cprintf("%s,", IA32flags[i]);
+        }
+    }
+    cprintf("IOPL=%d\n", (tf->tf_eflags & FL_IOPL_MASK) >> 12);
+
+    if (!trap_in_kernel(tf)) {
+        cprintf("  esp  0x%08x\n", tf->tf_esp);
+        cprintf("  ss   0x----%04x\n", tf->tf_ss);
+    }
+}
+
+void
+print_regs(struct pushregs *regs) {
+    cprintf("  edi  0x%08x\n", regs->reg_edi);
+    cprintf("  esi  0x%08x\n", regs->reg_esi);
+    cprintf("  ebp  0x%08x\n", regs->reg_ebp);
+    cprintf("  oesp 0x%08x\n", regs->reg_oesp);
+    cprintf("  ebx  0x%08x\n", regs->reg_ebx);
+    cprintf("  edx  0x%08x\n", regs->reg_edx);
+    cprintf("  ecx  0x%08x\n", regs->reg_ecx);
+    cprintf("  eax  0x%08x\n", regs->reg_eax);
+}
+
+/* trap_dispatch - dispatch based on what type of trap occurred */
+static void
+trap_dispatch(struct trapframe *tf) {
+    char c;
+
+    switch (tf->tf_trapno) {
+    case IRQ_OFFSET + IRQ_TIMER:
+        /* LAB1 YOUR CODE : STEP 3 */
+        /* handle the timer interrupt */
+        /* (1) After a timer interrupt, you should record this event using a global variable (increase it), such as ticks in kern/driver/clock.c
+         * (2) Every TICK_NUM cycle, you can print some info using a funciton, such as print_ticks().
+         * (3) Too Simple? Yes, I think so!
+         */
+        ticks ++;
+        if (ticks % TICK_NUM == 0) {
+            print_ticks();
+        }
+        break;
+    case IRQ_OFFSET + IRQ_COM1:
+        c = cons_getc();
+        cprintf("serial [%03d] %c\n", c, c);
+        break;
+    case IRQ_OFFSET + IRQ_KBD:
+        c = cons_getc();
+        cprintf("kbd [%03d] %c\n", c, c);
+        break;
+    //LAB1 CHALLENGE 1 : YOUR CODE you should modify below codes.
+    case T_SWITCH_TOU:
+    case T_SWITCH_TOK:
+        panic("T_SWITCH_** ??\n");
+        break;
+    case IRQ_OFFSET + IRQ_IDE1:
+    case IRQ_OFFSET + IRQ_IDE2:
+        /* do nothing */
+        break;
+    default:
+        // in kernel, it must be a mistake
+        if ((tf->tf_cs & 3) == 0) {
+            print_trapframe(tf);
+            panic("unexpected trap in kernel.\n");
+        }
+    }
+}
+
+/* *
+ * trap - handles or dispatches an exception/interrupt. if and when trap() returns,
+ * the code in kern/trap/trapentry.S restores the old CPU state saved in the
+ * trapframe and then uses the iret instruction to return from the exception.
+ * */
+void
+trap(struct trapframe *tf) {
+    // dispatch based on what type of trap occurred
+    trap_dispatch(tf);
+}
+

labcodes_answer/lab2_result/kern/trap/trap.h

@@ -0,0 +1,91 @@
+#ifndef __KERN_TRAP_TRAP_H__
+#define __KERN_TRAP_TRAP_H__
+
+#include <defs.h>
+
+/* Trap Numbers */
+
+/* Processor-defined: */
+#define T_DIVIDE                0   // divide error
+#define T_DEBUG                 1   // debug exception
+#define T_NMI                   2   // non-maskable interrupt
+#define T_BRKPT                 3   // breakpoint
+#define T_OFLOW                 4   // overflow
+#define T_BOUND                 5   // bounds check
+#define T_ILLOP                 6   // illegal opcode
+#define T_DEVICE                7   // device not available
+#define T_DBLFLT                8   // double fault
+// #define T_COPROC             9   // reserved (not used since 486)
+#define T_TSS                   10  // invalid task switch segment
+#define T_SEGNP                 11  // segment not present
+#define T_STACK                 12  // stack exception
+#define T_GPFLT                 13  // general protection fault
+#define T_PGFLT                 14  // page fault
+// #define T_RES                15  // reserved
+#define T_FPERR                 16  // floating point error
+#define T_ALIGN                 17  // aligment check
+#define T_MCHK                  18  // machine check
+#define T_SIMDERR               19  // SIMD floating point error
+
+#define T_SYSCALL               0x80 // SYSCALL, ONLY FOR THIS PROJ
+
+/* Hardware IRQ numbers. We receive these as (IRQ_OFFSET + IRQ_xx) */
+#define IRQ_OFFSET              32  // IRQ 0 corresponds to int IRQ_OFFSET
+
+#define IRQ_TIMER               0
+#define IRQ_KBD                 1
+#define IRQ_COM1                4
+#define IRQ_IDE1                14
+#define IRQ_IDE2                15
+#define IRQ_ERROR               19
+#define IRQ_SPURIOUS            31
+
+/* *
+ * These are arbitrarily chosen, but with care not to overlap
+ * processor defined exceptions or interrupt vectors.
+ * */
+#define T_SWITCH_TOU                120    // user/kernel switch
+#define T_SWITCH_TOK                121    // user/kernel switch
+
+/* registers as pushed by pushal */
+struct pushregs {
+    uint32_t reg_edi;
+    uint32_t reg_esi;
+    uint32_t reg_ebp;
+    uint32_t reg_oesp;          /* Useless */
+    uint32_t reg_ebx;
+    uint32_t reg_edx;
+    uint32_t reg_ecx;
+    uint32_t reg_eax;
+};
+
+struct trapframe {
+    struct pushregs tf_regs;
+    uint16_t tf_gs;
+    uint16_t tf_padding0;
+    uint16_t tf_fs;
+    uint16_t tf_padding1;
+    uint16_t tf_es;
+    uint16_t tf_padding2;
+    uint16_t tf_ds;
+    uint16_t tf_padding3;
+    uint32_t tf_trapno;
+    /* below here defined by x86 hardware */
+    uint32_t tf_err;
+    uintptr_t tf_eip;
+    uint16_t tf_cs;
+    uint16_t tf_padding4;
+    uint32_t tf_eflags;
+    /* below here only when crossing rings, such as from user to kernel */
+    uintptr_t tf_esp;
+    uint16_t tf_ss;
+    uint16_t tf_padding5;
+} __attribute__((packed));
+
+void idt_init(void);
+void print_trapframe(struct trapframe *tf);
+void print_regs(struct pushregs *regs);
+bool trap_in_kernel(struct trapframe *tf);
+
+#endif /* !__KERN_TRAP_TRAP_H__ */
+

labcodes_answer/lab2_result/kern/trap/trapentry.S

@@ -0,0 +1,44 @@
+#include <memlayout.h>
+
+# vectors.S sends all traps here.
+.text
+.globl __alltraps
+__alltraps:
+    # push registers to build a trap frame
+    # therefore make the stack look like a struct trapframe
+    pushl %ds
+    pushl %es
+    pushl %fs
+    pushl %gs
+    pushal
+
+    # load GD_KDATA into %ds and %es to set up data segments for kernel
+    movl $GD_KDATA, %eax
+    movw %ax, %ds
+    movw %ax, %es
+
+    # push %esp to pass a pointer to the trapframe as an argument to trap()
+    pushl %esp
+
+    # call trap(tf), where tf=%esp
+    call trap
+
+    # pop the pushed stack pointer
+    popl %esp
+
+    # return falls through to trapret...
+.globl __trapret
+__trapret:
+    # restore registers from stack
+    popal
+
+    # restore %ds, %es, %fs and %gs
+    popl %gs
+    popl %fs
+    popl %es
+    popl %ds
+
+    # get rid of the trap number and error code
+    addl $0x8, %esp
+    iret
+

labcodes_answer/lab2_result/libs/atomic.h

@@ -0,0 +1,57 @@
+#ifndef __LIBS_ATOMIC_H__
+#define __LIBS_ATOMIC_H__
+
+/* Atomic operations that C can't guarantee us. Useful for resource counting etc.. */
+
+static inline void set_bit(int nr, volatile void *addr) __attribute__((always_inline));
+static inline void clear_bit(int nr, volatile void *addr) __attribute__((always_inline));
+static inline void change_bit(int nr, volatile void *addr) __attribute__((always_inline));
+static inline bool test_bit(int nr, volatile void *addr) __attribute__((always_inline));
+
+/* *
+ * set_bit - Atomically set a bit in memory
+ * @nr:     the bit to set
+ * @addr:   the address to start counting from
+ *
+ * Note that @nr may be almost arbitrarily large; this function is not
+ * restricted to acting on a single-word quantity.
+ * */
+static inline void
+set_bit(int nr, volatile void *addr) {
+    asm volatile ("btsl %1, %0" :"=m" (*(volatile long *)addr) : "Ir" (nr));
+}
+
+/* *
+ * clear_bit - Atomically clears a bit in memory
+ * @nr:     the bit to clear
+ * @addr:   the address to start counting from
+ * */
+static inline void
+clear_bit(int nr, volatile void *addr) {
+    asm volatile ("btrl %1, %0" :"=m" (*(volatile long *)addr) : "Ir" (nr));
+}
+
+/* *
+ * change_bit - Atomically toggle a bit in memory
+ * @nr:     the bit to change
+ * @addr:   the address to start counting from
+ * */
+static inline void
+change_bit(int nr, volatile void *addr) {
+    asm volatile ("btcl %1, %0" :"=m" (*(volatile long *)addr) : "Ir" (nr));
+}
+
+/* *
+ * test_bit - Determine whether a bit is set
+ * @nr:     the bit to test
+ * @addr:   the address to count from
+ * */
+static inline bool
+test_bit(int nr, volatile void *addr) {
+    int oldbit;
+    asm volatile ("btl %2, %1; sbbl %0,%0" : "=r" (oldbit) : "m" (*(volatile long *)addr), "Ir" (nr));
+    return oldbit != 0;
+}
+
+#endif /* !__LIBS_ATOMIC_H__ */
+

labcodes_answer/lab2_result/libs/defs.h

@@ -0,0 +1,68 @@
+#ifndef __LIBS_DEFS_H__
+#define __LIBS_DEFS_H__
+
+#ifndef NULL
+#define NULL ((void *)0)
+#endif
+
+#define __always_inline inline __attribute__((always_inline))
+#define __noinline __attribute__((noinline))
+#define __noreturn __attribute__((noreturn))
+
+/* Represents true-or-false values */
+typedef int bool;
+
+/* Explicitly-sized versions of integer types */
+typedef char int8_t;
+typedef unsigned char uint8_t;
+typedef short int16_t;
+typedef unsigned short uint16_t;
+typedef int int32_t;
+typedef unsigned int uint32_t;
+typedef long long int64_t;
+typedef unsigned long long uint64_t;
+
+/* *
+ * Pointers and addresses are 32 bits long.
+ * We use pointer types to represent addresses,
+ * uintptr_t to represent the numerical values of addresses.
+ * */
+typedef int32_t intptr_t;
+typedef uint32_t uintptr_t;
+
+/* size_t is used for memory object sizes */
+typedef uintptr_t size_t;
+
+/* used for page numbers */
+typedef size_t ppn_t;
+
+/* *
+ * Rounding operations (efficient when n is a power of 2)
+ * Round down to the nearest multiple of n
+ * */
+#define ROUNDDOWN(a, n) ({                                          \
+            size_t __a = (size_t)(a);                               \
+            (typeof(a))(__a - __a % (n));                           \
+        })
+
+/* Round up to the nearest multiple of n */
+#define ROUNDUP(a, n) ({                                            \
+            size_t __n = (size_t)(n);                               \
+            (typeof(a))(ROUNDDOWN((size_t)(a) + __n - 1, __n));     \
+        })
+
+/* Return the offset of 'member' relative to the beginning of a struct type */
+#define offsetof(type, member)                                      \
+    ((size_t)(&((type *)0)->member))
+
+/* *
+ * to_struct - get the struct from a ptr
+ * @ptr:    a struct pointer of member
+ * @type:   the type of the struct this is embedded in
+ * @member: the name of the member within the struct
+ * */
+#define to_struct(ptr, type, member)                               \
+    ((type *)((char *)(ptr) - offsetof(type, member)))
+
+#endif /* !__LIBS_DEFS_H__ */
+

labcodes_answer/lab2_result/libs/elf.h

@@ -0,0 +1,40 @@
+#ifndef __LIBS_ELF_H__
+#define __LIBS_ELF_H__
+
+#include <defs.h>
+
+#define ELF_MAGIC   0x464C457FU         // "\x7FELF" in little endian
+
+/* file header */
+struct elfhdr {
+    uint32_t e_magic;     // must equal ELF_MAGIC
+    uint8_t e_elf[12];
+    uint16_t e_type;      // 1=relocatable, 2=executable, 3=shared object, 4=core image
+    uint16_t e_machine;   // 3=x86, 4=68K, etc.
+    uint32_t e_version;   // file version, always 1
+    uint32_t e_entry;     // entry point if executable
+    uint32_t e_phoff;     // file position of program header or 0
+    uint32_t e_shoff;     // file position of section header or 0
+    uint32_t e_flags;     // architecture-specific flags, usually 0
+    uint16_t e_ehsize;    // size of this elf header
+    uint16_t e_phentsize; // size of an entry in program header
+    uint16_t e_phnum;     // number of entries in program header or 0
+    uint16_t e_shentsize; // size of an entry in section header
+    uint16_t e_shnum;     // number of entries in section header or 0
+    uint16_t e_shstrndx;  // section number that contains section name strings
+};
+
+/* program section header */
+struct proghdr {
+    uint32_t p_type;   // loadable code or data, dynamic linking info,etc.
+    uint32_t p_offset; // file offset of segment
+    uint32_t p_va;     // virtual address to map segment
+    uint32_t p_pa;     // physical address, not used
+    uint32_t p_filesz; // size of segment in file
+    uint32_t p_memsz;  // size of segment in memory (bigger if contains bss）
+    uint32_t p_flags;  // read/write/execute bits
+    uint32_t p_align;  // required alignment, invariably hardware page size
+};
+
+#endif /* !__LIBS_ELF_H__ */
+

labcodes_answer/lab2_result/libs/error.h

@@ -0,0 +1,16 @@
+#ifndef __LIBS_ERROR_H__
+#define __LIBS_ERROR_H__
+
+/* kernel error codes -- keep in sync with list in lib/printfmt.c */
+#define E_UNSPECIFIED       1   // Unspecified or unknown problem
+#define E_BAD_PROC          2   // Process doesn't exist or otherwise
+#define E_INVAL             3   // Invalid parameter
+#define E_NO_MEM            4   // Request failed due to memory shortage
+#define E_NO_FREE_PROC      5   // Attempt to create a new process beyond
+#define E_FAULT             6   // Memory fault
+
+/* the maximum allowed */
+#define MAXERROR            6
+
+#endif /* !__LIBS_ERROR_H__ */
+

labcodes_answer/lab2_result/libs/list.h

@@ -0,0 +1,163 @@
+#ifndef __LIBS_LIST_H__
+#define __LIBS_LIST_H__
+
+#ifndef __ASSEMBLER__
+
+#include <defs.h>
+
+/* *
+ * Simple doubly linked list implementation.
+ *
+ * Some of the internal functions ("__xxx") are useful when manipulating
+ * whole lists rather than single entries, as sometimes we already know
+ * the next/prev entries and we can generate better code by using them
+ * directly rather than using the generic single-entry routines.
+ * */
+
+struct list_entry {
+    struct list_entry *prev, *next;
+};
+
+typedef struct list_entry list_entry_t;
+
+static inline void list_init(list_entry_t *elm) __attribute__((always_inline));
+static inline void list_add(list_entry_t *listelm, list_entry_t *elm) __attribute__((always_inline));
+static inline void list_add_before(list_entry_t *listelm, list_entry_t *elm) __attribute__((always_inline));
+static inline void list_add_after(list_entry_t *listelm, list_entry_t *elm) __attribute__((always_inline));
+static inline void list_del(list_entry_t *listelm) __attribute__((always_inline));
+static inline void list_del_init(list_entry_t *listelm) __attribute__((always_inline));
+static inline bool list_empty(list_entry_t *list) __attribute__((always_inline));
+static inline list_entry_t *list_next(list_entry_t *listelm) __attribute__((always_inline));
+static inline list_entry_t *list_prev(list_entry_t *listelm) __attribute__((always_inline));
+
+static inline void __list_add(list_entry_t *elm, list_entry_t *prev, list_entry_t *next) __attribute__((always_inline));
+static inline void __list_del(list_entry_t *prev, list_entry_t *next) __attribute__((always_inline));
+
+/* *
+ * list_init - initialize a new entry
+ * @elm:        new entry to be initialized
+ * */
+static inline void
+list_init(list_entry_t *elm) {
+    elm->prev = elm->next = elm;
+}
+
+/* *
+ * list_add - add a new entry
+ * @listelm:    list head to add after
+ * @elm:        new entry to be added
+ *
+ * Insert the new element @elm *after* the element @listelm which
+ * is already in the list.
+ * */
+static inline void
+list_add(list_entry_t *listelm, list_entry_t *elm) {
+    list_add_after(listelm, elm);
+}
+
+/* *
+ * list_add_before - add a new entry
+ * @listelm:    list head to add before
+ * @elm:        new entry to be added
+ *
+ * Insert the new element @elm *before* the element @listelm which
+ * is already in the list.
+ * */
+static inline void
+list_add_before(list_entry_t *listelm, list_entry_t *elm) {
+    __list_add(elm, listelm->prev, listelm);
+}
+
+/* *
+ * list_add_after - add a new entry
+ * @listelm:    list head to add after
+ * @elm:        new entry to be added
+ *
+ * Insert the new element @elm *after* the element @listelm which
+ * is already in the list.
+ * */
+static inline void
+list_add_after(list_entry_t *listelm, list_entry_t *elm) {
+    __list_add(elm, listelm, listelm->next);
+}
+
+/* *
+ * list_del - deletes entry from list
+ * @listelm:    the element to delete from the list
+ *
+ * Note: list_empty() on @listelm does not return true after this, the entry is
+ * in an undefined state.
+ * */
+static inline void
+list_del(list_entry_t *listelm) {
+    __list_del(listelm->prev, listelm->next);
+}
+
+/* *
+ * list_del_init - deletes entry from list and reinitialize it.
+ * @listelm:    the element to delete from the list.
+ *
+ * Note: list_empty() on @listelm returns true after this.
+ * */
+static inline void
+list_del_init(list_entry_t *listelm) {
+    list_del(listelm);
+    list_init(listelm);
+}
+
+/* *
+ * list_empty - tests whether a list is empty
+ * @list:       the list to test.
+ * */
+static inline bool
+list_empty(list_entry_t *list) {
+    return list->next == list;
+}
+
+/* *
+ * list_next - get the next entry
+ * @listelm:    the list head
+ **/
+static inline list_entry_t *
+list_next(list_entry_t *listelm) {
+    return listelm->next;
+}
+
+/* *
+ * list_prev - get the previous entry
+ * @listelm:    the list head
+ **/
+static inline list_entry_t *
+list_prev(list_entry_t *listelm) {
+    return listelm->prev;
+}
+
+/* *
+ * Insert a new entry between two known consecutive entries.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ * */
+static inline void
+__list_add(list_entry_t *elm, list_entry_t *prev, list_entry_t *next) {
+    prev->next = next->prev = elm;
+    elm->next = next;
+    elm->prev = prev;
+}
+
+/* *
+ * Delete a list entry by making the prev/next entries point to each other.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ * */
+static inline void
+__list_del(list_entry_t *prev, list_entry_t *next) {
+    prev->next = next;
+    next->prev = prev;
+}
+
+#endif /* !__ASSEMBLER__ */
+
+#endif /* !__LIBS_LIST_H__ */
+

labcodes_answer/lab2_result/libs/printfmt.c

@@ -0,0 +1,340 @@
+#include <defs.h>
+#include <x86.h>
+#include <error.h>
+#include <stdio.h>
+#include <string.h>
+
+/* *
+ * Space or zero padding and a field width are supported for the numeric
+ * formats only.
+ *
+ * The special format %e takes an integer error code
+ * and prints a string describing the error.
+ * The integer may be positive or negative,
+ * so that -E_NO_MEM and E_NO_MEM are equivalent.
+ * */
+
+static const char * const error_string[MAXERROR + 1] = {
+    [0]                     NULL,
+    [E_UNSPECIFIED]         "unspecified error",
+    [E_BAD_PROC]            "bad process",
+    [E_INVAL]               "invalid parameter",
+    [E_NO_MEM]              "out of memory",
+    [E_NO_FREE_PROC]        "out of processes",
+    [E_FAULT]               "segmentation fault",
+};
+
+/* *
+ * printnum - print a number (base <= 16) in reverse order
+ * @putch:      specified putch function, print a single character
+ * @putdat:     used by @putch function
+ * @num:        the number will be printed
+ * @base:       base for print, must be in [1, 16]
+ * @width:      maximum number of digits, if the actual width is less than @width, use @padc instead
+ * @padc:       character that padded on the left if the actual width is less than @width
+ * */
+static void
+printnum(void (*putch)(int, void*), void *putdat,
+        unsigned long long num, unsigned base, int width, int padc) {
+    unsigned long long result = num;
+    unsigned mod = do_div(result, base);
+
+    // first recursively print all preceding (more significant) digits
+    if (num >= base) {
+        printnum(putch, putdat, result, base, width - 1, padc);
+    } else {
+        // print any needed pad characters before first digit
+        while (-- width > 0)
+            putch(padc, putdat);
+    }
+    // then print this (the least significant) digit
+    putch("0123456789abcdef"[mod], putdat);
+}
+
+/* *
+ * getuint - get an unsigned int of various possible sizes from a varargs list
+ * @ap:         a varargs list pointer
+ * @lflag:      determines the size of the vararg that @ap points to
+ * */
+static unsigned long long
+getuint(va_list *ap, int lflag) {
+    if (lflag >= 2) {
+        return va_arg(*ap, unsigned long long);
+    }
+    else if (lflag) {
+        return va_arg(*ap, unsigned long);
+    }
+    else {
+        return va_arg(*ap, unsigned int);
+    }
+}
+
+/* *
+ * getint - same as getuint but signed, we can't use getuint because of sign extension
+ * @ap:         a varargs list pointer
+ * @lflag:      determines the size of the vararg that @ap points to
+ * */
+static long long
+getint(va_list *ap, int lflag) {
+    if (lflag >= 2) {
+        return va_arg(*ap, long long);
+    }
+    else if (lflag) {
+        return va_arg(*ap, long);
+    }
+    else {
+        return va_arg(*ap, int);
+    }
+}
+
+/* *
+ * printfmt - format a string and print it by using putch
+ * @putch:      specified putch function, print a single character
+ * @putdat:     used by @putch function
+ * @fmt:        the format string to use
+ * */
+void
+printfmt(void (*putch)(int, void*), void *putdat, const char *fmt, ...) {
+    va_list ap;
+
+    va_start(ap, fmt);
+    vprintfmt(putch, putdat, fmt, ap);
+    va_end(ap);
+}
+
+/* *
+ * vprintfmt - format a string and print it by using putch, it's called with a va_list
+ * instead of a variable number of arguments
+ * @putch:      specified putch function, print a single character
+ * @putdat:     used by @putch function
+ * @fmt:        the format string to use
+ * @ap:         arguments for the format string
+ *
+ * Call this function if you are already dealing with a va_list.
+ * Or you probably want printfmt() instead.
+ * */
+void
+vprintfmt(void (*putch)(int, void*), void *putdat, const char *fmt, va_list ap) {
+    register const char *p;
+    register int ch, err;
+    unsigned long long num;
+    int base, width, precision, lflag, altflag;
+
+    while (1) {
+        while ((ch = *(unsigned char *)fmt ++) != '%') {
+            if (ch == '\0') {
+                return;
+            }
+            putch(ch, putdat);
+        }
+
+        // Process a %-escape sequence
+        char padc = ' ';
+        width = precision = -1;
+        lflag = altflag = 0;
+
+    reswitch:
+        switch (ch = *(unsigned char *)fmt ++) {
+
+        // flag to pad on the right
+        case '-':
+            padc = '-';
+            goto reswitch;
+
+        // flag to pad with 0's instead of spaces
+        case '0':
+            padc = '0';
+            goto reswitch;
+
+        // width field
+        case '1' ... '9':
+            for (precision = 0; ; ++ fmt) {
+                precision = precision * 10 + ch - '0';
+                ch = *fmt;
+                if (ch < '0' || ch > '9') {
+                    break;
+                }
+            }
+            goto process_precision;
+
+        case '*':
+            precision = va_arg(ap, int);
+            goto process_precision;
+
+        case '.':
+            if (width < 0)
+                width = 0;
+            goto reswitch;
+
+        case '#':
+            altflag = 1;
+            goto reswitch;
+
+        process_precision:
+            if (width < 0)
+                width = precision, precision = -1;
+            goto reswitch;
+
+        // long flag (doubled for long long)
+        case 'l':
+            lflag ++;
+            goto reswitch;
+
+        // character
+        case 'c':
+            putch(va_arg(ap, int), putdat);
+            break;
+
+        // error message
+        case 'e':
+            err = va_arg(ap, int);
+            if (err < 0) {
+                err = -err;
+            }
+            if (err > MAXERROR || (p = error_string[err]) == NULL) {
+                printfmt(putch, putdat, "error %d", err);
+            }
+            else {
+                printfmt(putch, putdat, "%s", p);
+            }
+            break;
+
+        // string
+        case 's':
+            if ((p = va_arg(ap, char *)) == NULL) {
+                p = "(null)";
+            }
+            if (width > 0 && padc != '-') {
+                for (width -= strnlen(p, precision); width > 0; width --) {
+                    putch(padc, putdat);
+                }
+            }
+            for (; (ch = *p ++) != '\0' && (precision < 0 || -- precision >= 0); width --) {
+                if (altflag && (ch < ' ' || ch > '~')) {
+                    putch('?', putdat);
+                }
+                else {
+                    putch(ch, putdat);
+                }
+            }
+            for (; width > 0; width --) {
+                putch(' ', putdat);
+            }
+            break;
+
+        // (signed) decimal
+        case 'd':
+            num = getint(&ap, lflag);
+            if ((long long)num < 0) {
+                putch('-', putdat);
+                num = -(long long)num;
+            }
+            base = 10;
+            goto number;
+
+        // unsigned decimal
+        case 'u':
+            num = getuint(&ap, lflag);
+            base = 10;
+            goto number;
+
+        // (unsigned) octal
+        case 'o':
+            num = getuint(&ap, lflag);
+            base = 8;
+            goto number;
+
+        // pointer
+        case 'p':
+            putch('0', putdat);
+            putch('x', putdat);
+            num = (unsigned long long)(uintptr_t)va_arg(ap, void *);
+            base = 16;
+            goto number;
+
+        // (unsigned) hexadecimal
+        case 'x':
+            num = getuint(&ap, lflag);
+            base = 16;
+        number:
+            printnum(putch, putdat, num, base, width, padc);
+            break;
+
+        // escaped '%' character
+        case '%':
+            putch(ch, putdat);
+            break;
+
+        // unrecognized escape sequence - just print it literally
+        default:
+            putch('%', putdat);
+            for (fmt --; fmt[-1] != '%'; fmt --)
+                /* do nothing */;
+            break;
+        }
+    }
+}
+
+/* sprintbuf is used to save enough information of a buffer */
+struct sprintbuf {
+    char *buf;          // address pointer points to the first unused memory
+    char *ebuf;         // points the end of the buffer
+    int cnt;            // the number of characters that have been placed in this buffer
+};
+
+/* *
+ * sprintputch - 'print' a single character in a buffer
+ * @ch:         the character will be printed
+ * @b:          the buffer to place the character @ch
+ * */
+static void
+sprintputch(int ch, struct sprintbuf *b) {
+    b->cnt ++;
+    if (b->buf < b->ebuf) {
+        *b->buf ++ = ch;
+    }
+}
+
+/* *
+ * snprintf - format a string and place it in a buffer
+ * @str:        the buffer to place the result into
+ * @size:       the size of buffer, including the trailing null space
+ * @fmt:        the format string to use
+ * */
+int
+snprintf(char *str, size_t size, const char *fmt, ...) {
+    va_list ap;
+    int cnt;
+    va_start(ap, fmt);
+    cnt = vsnprintf(str, size, fmt, ap);
+    va_end(ap);
+    return cnt;
+}
+
+/* *
+ * vsnprintf - format a string and place it in a buffer, it's called with a va_list
+ * instead of a variable number of arguments
+ * @str:        the buffer to place the result into
+ * @size:       the size of buffer, including the trailing null space
+ * @fmt:        the format string to use
+ * @ap:         arguments for the format string
+ *
+ * The return value is the number of characters which would be generated for the
+ * given input, excluding the trailing '\0'.
+ *
+ * Call this function if you are already dealing with a va_list.
+ * Or you probably want snprintf() instead.
+ * */
+int
+vsnprintf(char *str, size_t size, const char *fmt, va_list ap) {
+    struct sprintbuf b = {str, str + size - 1, 0};
+    if (str == NULL || b.buf > b.ebuf) {
+        return -E_INVAL;
+    }
+    // print the string to the buffer
+    vprintfmt((void*)sprintputch, &b, fmt, ap);
+    // null terminate the buffer
+    *b.buf = '\0';
+    return b.cnt;
+}
+

labcodes_answer/lab2_result/libs/stdarg.h

@@ -0,0 +1,12 @@
+#ifndef __LIBS_STDARG_H__
+#define __LIBS_STDARG_H__
+
+/* compiler provides size of save area */
+typedef __builtin_va_list va_list;
+
+#define va_start(ap, last)              (__builtin_va_start(ap, last))
+#define va_arg(ap, type)                (__builtin_va_arg(ap, type))
+#define va_end(ap)                      /*nothing*/
+
+#endif /* !__LIBS_STDARG_H__ */
+

labcodes_answer/lab2_result/libs/stdio.h

@@ -0,0 +1,24 @@
+#ifndef __LIBS_STDIO_H__
+#define __LIBS_STDIO_H__
+
+#include <defs.h>
+#include <stdarg.h>
+
+/* kern/libs/stdio.c */
+int cprintf(const char *fmt, ...);
+int vcprintf(const char *fmt, va_list ap);
+void cputchar(int c);
+int cputs(const char *str);
+int getchar(void);
+
+/* kern/libs/readline.c */
+char *readline(const char *prompt);
+
+/* libs/printfmt.c */
+void printfmt(void (*putch)(int, void *), void *putdat, const char *fmt, ...);
+void vprintfmt(void (*putch)(int, void *), void *putdat, const char *fmt, va_list ap);
+int snprintf(char *str, size_t size, const char *fmt, ...);
+int vsnprintf(char *str, size_t size, const char *fmt, va_list ap);
+
+#endif /* !__LIBS_STDIO_H__ */
+

labcodes_answer/lab2_result/libs/string.c

@@ -0,0 +1,367 @@
+#include <string.h>
+#include <x86.h>
+
+/* *
+ * strlen - calculate the length of the string @s, not including
+ * the terminating '\0' character.
+ * @s:      the input string
+ *
+ * The strlen() function returns the length of string @s.
+ * */
+size_t
+strlen(const char *s) {
+    size_t cnt = 0;
+    while (*s ++ != '\0') {
+        cnt ++;
+    }
+    return cnt;
+}
+
+/* *
+ * strnlen - calculate the length of the string @s, not including
+ * the terminating '\0' char acter, but at most @len.
+ * @s:      the input string
+ * @len:    the max-length that function will scan
+ *
+ * Note that, this function looks only at the first @len characters
+ * at @s, and never beyond @s + @len.
+ *
+ * The return value is strlen(s), if that is less than @len, or
+ * @len if there is no '\0' character among the first @len characters
+ * pointed by @s.
+ * */
+size_t
+strnlen(const char *s, size_t len) {
+    size_t cnt = 0;
+    while (cnt < len && *s ++ != '\0') {
+        cnt ++;
+    }
+    return cnt;
+}
+
+/* *
+ * strcpy - copies the string pointed by @src into the array pointed by @dst,
+ * including the terminating null character.
+ * @dst:    pointer to the destination array where the content is to be copied
+ * @src:    string to be copied
+ *
+ * The return value is @dst.
+ *
+ * To avoid overflows, the size of array pointed by @dst should be long enough to
+ * contain the same string as @src (including the terminating null character), and
+ * should not overlap in memory with @src.
+ * */
+char *
+strcpy(char *dst, const char *src) {
+#ifdef __HAVE_ARCH_STRCPY
+    return __strcpy(dst, src);
+#else
+    char *p = dst;
+    while ((*p ++ = *src ++) != '\0')
+        /* nothing */;
+    return dst;
+#endif /* __HAVE_ARCH_STRCPY */
+}
+
+/* *
+ * strncpy - copies the first @len characters of @src to @dst. If the end of string @src
+ * if found before @len characters have been copied, @dst is padded with '\0' until a
+ * total of @len characters have been written to it.
+ * @dst:    pointer to the destination array where the content is to be copied
+ * @src:    string to be copied
+ * @len:    maximum number of characters to be copied from @src
+ *
+ * The return value is @dst
+ * */
+char *
+strncpy(char *dst, const char *src, size_t len) {
+    char *p = dst;
+    while (len > 0) {
+        if ((*p = *src) != '\0') {
+            src ++;
+        }
+        p ++, len --;
+    }
+    return dst;
+}
+
+/* *
+ * strcmp - compares the string @s1 and @s2
+ * @s1:     string to be compared
+ * @s2:     string to be compared
+ *
+ * This function starts comparing the first character of each string. If
+ * they are equal to each other, it continues with the following pairs until
+ * the characters differ or until a terminanting null-character is reached.
+ *
+ * Returns an integral value indicating the relationship between the strings:
+ * - A zero value indicates that both strings are equal;
+ * - A value greater than zero indicates that the first character that does
+ *   not match has a greater value in @s1 than in @s2;
+ * - And a value less than zero indicates the opposite.
+ * */
+int
+strcmp(const char *s1, const char *s2) {
+#ifdef __HAVE_ARCH_STRCMP
+    return __strcmp(s1, s2);
+#else
+    while (*s1 != '\0' && *s1 == *s2) {
+        s1 ++, s2 ++;
+    }
+    return (int)((unsigned char)*s1 - (unsigned char)*s2);
+#endif /* __HAVE_ARCH_STRCMP */
+}
+
+/* *
+ * strncmp - compares up to @n characters of the string @s1 to those of the string @s2
+ * @s1:     string to be compared
+ * @s2:     string to be compared
+ * @n:      maximum number of characters to compare
+ *
+ * This function starts comparing the first character of each string. If
+ * they are equal to each other, it continues with the following pairs until
+ * the characters differ, until a terminating null-character is reached, or
+ * until @n characters match in both strings, whichever happens first.
+ * */
+int
+strncmp(const char *s1, const char *s2, size_t n) {
+    while (n > 0 && *s1 != '\0' && *s1 == *s2) {
+        n --, s1 ++, s2 ++;
+    }
+    return (n == 0) ? 0 : (int)((unsigned char)*s1 - (unsigned char)*s2);
+}
+
+/* *
+ * strchr - locates first occurrence of character in string
+ * @s:      the input string
+ * @c:      character to be located
+ *
+ * The strchr() function returns a pointer to the first occurrence of
+ * character in @s. If the value is not found, the function returns 'NULL'.
+ * */
+char *
+strchr(const char *s, char c) {
+    while (*s != '\0') {
+        if (*s == c) {
+            return (char *)s;
+        }
+        s ++;
+    }
+    return NULL;
+}
+
+/* *
+ * strfind - locates first occurrence of character in string
+ * @s:      the input string
+ * @c:      character to be located
+ *
+ * The strfind() function is like strchr() except that if @c is
+ * not found in @s, then it returns a pointer to the null byte at the
+ * end of @s, rather than 'NULL'.
+ * */
+char *
+strfind(const char *s, char c) {
+    while (*s != '\0') {
+        if (*s == c) {
+            break;
+        }
+        s ++;
+    }
+    return (char *)s;
+}
+
+/* *
+ * strtol - converts string to long integer
+ * @s:      the input string that contains the representation of an integer number
+ * @endptr: reference to an object of type char *, whose value is set by the
+ *          function to the next character in @s after the numerical value. This
+ *          parameter can also be a null pointer, in which case it is not used.
+ * @base:   x
+ *
+ * The function first discards as many whitespace characters as necessary until
+ * the first non-whitespace character is found. Then, starting from this character,
+ * takes as many characters as possible that are valid following a syntax that
+ * depends on the base parameter, and interprets them as a numerical value. Finally,
+ * a pointer to the first character following the integer representation in @s
+ * is stored in the object pointed by @endptr.
+ *
+ * If the value of base is zero, the syntax expected is similar to that of
+ * integer constants, which is formed by a succession of:
+ * - An optional plus or minus sign;
+ * - An optional prefix indicating octal or hexadecimal base ("0" or "0x" respectively)
+ * - A sequence of decimal digits (if no base prefix was specified) or either octal
+ *   or hexadecimal digits if a specific prefix is present
+ *
+ * If the base value is between 2 and 36, the format expected for the integral number
+ * is a succession of the valid digits and/or letters needed to represent integers of
+ * the specified radix (starting from '0' and up to 'z'/'Z' for radix 36). The
+ * sequence may optionally be preceded by a plus or minus sign and, if base is 16,
+ * an optional "0x" or "0X" prefix.
+ *
+ * The strtol() function returns the converted integral number as a long int value.
+ * */
+long
+strtol(const char *s, char **endptr, int base) {
+    int neg = 0;
+    long val = 0;
+
+    // gobble initial whitespace
+    while (*s == ' ' || *s == '\t') {
+        s ++;
+    }
+
+    // plus/minus sign
+    if (*s == '+') {
+        s ++;
+    }
+    else if (*s == '-') {
+        s ++, neg = 1;
+    }
+
+    // hex or octal base prefix
+    if ((base == 0 || base == 16) && (s[0] == '0' && s[1] == 'x')) {
+        s += 2, base = 16;
+    }
+    else if (base == 0 && s[0] == '0') {
+        s ++, base = 8;
+    }
+    else if (base == 0) {
+        base = 10;
+    }
+
+    // digits
+    while (1) {
+        int dig;
+
+        if (*s >= '0' && *s <= '9') {
+            dig = *s - '0';
+        }
+        else if (*s >= 'a' && *s <= 'z') {
+            dig = *s - 'a' + 10;
+        }
+        else if (*s >= 'A' && *s <= 'Z') {
+            dig = *s - 'A' + 10;
+        }
+        else {
+            break;
+        }
+        if (dig >= base) {
+            break;
+        }
+        s ++, val = (val * base) + dig;
+        // we don't properly detect overflow!
+    }
+
+    if (endptr) {
+        *endptr = (char *) s;
+    }
+    return (neg ? -val : val);
+}
+
+/* *
+ * memset - sets the first @n bytes of the memory area pointed by @s
+ * to the specified value @c.
+ * @s:      pointer the the memory area to fill
+ * @c:      value to set
+ * @n:      number of bytes to be set to the value
+ *
+ * The memset() function returns @s.
+ * */
+void *
+memset(void *s, char c, size_t n) {
+#ifdef __HAVE_ARCH_MEMSET
+    return __memset(s, c, n);
+#else
+    char *p = s;
+    while (n -- > 0) {
+        *p ++ = c;
+    }
+    return s;
+#endif /* __HAVE_ARCH_MEMSET */
+}
+
+/* *
+ * memmove - copies the values of @n bytes from the location pointed by @src to
+ * the memory area pointed by @dst. @src and @dst are allowed to overlap.
+ * @dst     pointer to the destination array where the content is to be copied
+ * @src     pointer to the source of data to by copied
+ * @n:      number of bytes to copy
+ *
+ * The memmove() function returns @dst.
+ * */
+void *
+memmove(void *dst, const void *src, size_t n) {
+#ifdef __HAVE_ARCH_MEMMOVE
+    return __memmove(dst, src, n);
+#else
+    const char *s = src;
+    char *d = dst;
+    if (s < d && s + n > d) {
+        s += n, d += n;
+        while (n -- > 0) {
+            *-- d = *-- s;
+        }
+    } else {
+        while (n -- > 0) {
+            *d ++ = *s ++;
+        }
+    }
+    return dst;
+#endif /* __HAVE_ARCH_MEMMOVE */
+}
+
+/* *
+ * memcpy - copies the value of @n bytes from the location pointed by @src to
+ * the memory area pointed by @dst.
+ * @dst     pointer to the destination array where the content is to be copied
+ * @src     pointer to the source of data to by copied
+ * @n:      number of bytes to copy
+ *
+ * The memcpy() returns @dst.
+ *
+ * Note that, the function does not check any terminating null character in @src,
+ * it always copies exactly @n bytes. To avoid overflows, the size of arrays pointed
+ * by both @src and @dst, should be at least @n bytes, and should not overlap
+ * (for overlapping memory area, memmove is a safer approach).
+ * */
+void *
+memcpy(void *dst, const void *src, size_t n) {
+#ifdef __HAVE_ARCH_MEMCPY
+    return __memcpy(dst, src, n);
+#else
+    const char *s = src;
+    char *d = dst;
+    while (n -- > 0) {
+        *d ++ = *s ++;
+    }
+    return dst;
+#endif /* __HAVE_ARCH_MEMCPY */
+}
+
+/* *
+ * memcmp - compares two blocks of memory
+ * @v1:     pointer to block of memory
+ * @v2:     pointer to block of memory
+ * @n:      number of bytes to compare
+ *
+ * The memcmp() functions returns an integral value indicating the
+ * relationship between the content of the memory blocks:
+ * - A zero value indicates that the contents of both memory blocks are equal;
+ * - A value greater than zero indicates that the first byte that does not
+ *   match in both memory blocks has a greater value in @v1 than in @v2
+ *   as if evaluated as unsigned char values;
+ * - And a value less than zero indicates the opposite.
+ * */
+int
+memcmp(const void *v1, const void *v2, size_t n) {
+    const char *s1 = (const char *)v1;
+    const char *s2 = (const char *)v2;
+    while (n -- > 0) {
+        if (*s1 != *s2) {
+            return (int)((unsigned char)*s1 - (unsigned char)*s2);
+        }
+        s1 ++, s2 ++;
+    }
+    return 0;
+}
+

labcodes_answer/lab2_result/libs/string.h

@@ -0,0 +1,25 @@
+#ifndef __LIBS_STRING_H__
+#define __LIBS_STRING_H__
+
+#include <defs.h>
+
+size_t strlen(const char *s);
+size_t strnlen(const char *s, size_t len);
+
+char *strcpy(char *dst, const char *src);
+char *strncpy(char *dst, const char *src, size_t len);
+
+int strcmp(const char *s1, const char *s2);
+int strncmp(const char *s1, const char *s2, size_t n);
+
+char *strchr(const char *s, char c);
+char *strfind(const char *s, char c);
+long strtol(const char *s, char **endptr, int base);
+
+void *memset(void *s, char c, size_t n);
+void *memmove(void *dst, const void *src, size_t n);
+void *memcpy(void *dst, const void *src, size_t n);
+int memcmp(const void *v1, const void *v2, size_t n);
+
+#endif /* !__LIBS_STRING_H__ */
+

labcodes_answer/lab2_result/libs/x86.h

@@ -0,0 +1,302 @@
+#ifndef __LIBS_X86_H__
+#define __LIBS_X86_H__
+
+#include <defs.h>
+
+#define do_div(n, base) ({                                          \
+            unsigned long __upper, __low, __high, __mod, __base;    \
+            __base = (base);                                        \
+            asm ("" : "=a" (__low), "=d" (__high) : "A" (n));       \
+            __upper = __high;                                       \
+            if (__high != 0) {                                      \
+                __upper = __high % __base;                          \
+                __high = __high / __base;                           \
+            }                                                       \
+            asm ("divl %2" : "=a" (__low), "=d" (__mod)             \
+                : "rm" (__base), "0" (__low), "1" (__upper));       \
+            asm ("" : "=A" (n) : "a" (__low), "d" (__high));        \
+            __mod;                                                  \
+        })
+
+#define barrier() __asm__ __volatile__ ("" ::: "memory")
+
+static inline uint8_t inb(uint16_t port) __attribute__((always_inline));
+static inline void insl(uint32_t port, void *addr, int cnt) __attribute__((always_inline));
+static inline void outb(uint16_t port, uint8_t data) __attribute__((always_inline));
+static inline void outw(uint16_t port, uint16_t data) __attribute__((always_inline));
+static inline void outsl(uint32_t port, const void *addr, int cnt) __attribute__((always_inline));
+static inline uint32_t read_ebp(void) __attribute__((always_inline));
+static inline void breakpoint(void) __attribute__((always_inline));
+static inline uint32_t read_dr(unsigned regnum) __attribute__((always_inline));
+static inline void write_dr(unsigned regnum, uint32_t value) __attribute__((always_inline));
+
+/* Pseudo-descriptors used for LGDT, LLDT(not used) and LIDT instructions. */
+struct pseudodesc {
+    uint16_t pd_lim;        // Limit
+    uintptr_t pd_base;      // Base address
+} __attribute__ ((packed));
+
+static inline void lidt(struct pseudodesc *pd) __attribute__((always_inline));
+static inline void sti(void) __attribute__((always_inline));
+static inline void cli(void) __attribute__((always_inline));
+static inline void ltr(uint16_t sel) __attribute__((always_inline));
+static inline uint32_t read_eflags(void) __attribute__((always_inline));
+static inline void write_eflags(uint32_t eflags) __attribute__((always_inline));
+static inline void lcr0(uintptr_t cr0) __attribute__((always_inline));
+static inline void lcr3(uintptr_t cr3) __attribute__((always_inline));
+static inline uintptr_t rcr0(void) __attribute__((always_inline));
+static inline uintptr_t rcr1(void) __attribute__((always_inline));
+static inline uintptr_t rcr2(void) __attribute__((always_inline));
+static inline uintptr_t rcr3(void) __attribute__((always_inline));
+static inline void invlpg(void *addr) __attribute__((always_inline));
+
+static inline uint8_t
+inb(uint16_t port) {
+    uint8_t data;
+    asm volatile ("inb %1, %0" : "=a" (data) : "d" (port) : "memory");
+    return data;
+}
+
+static inline void
+insl(uint32_t port, void *addr, int cnt) {
+    asm volatile (
+        "cld;"
+        "repne; insl;"
+        : "=D" (addr), "=c" (cnt)
+        : "d" (port), "0" (addr), "1" (cnt)
+        : "memory", "cc");
+}
+
+static inline void
+outb(uint16_t port, uint8_t data) {
+    asm volatile ("outb %0, %1" :: "a" (data), "d" (port) : "memory");
+}
+
+static inline void
+outw(uint16_t port, uint16_t data) {
+    asm volatile ("outw %0, %1" :: "a" (data), "d" (port) : "memory");
+}
+
+static inline void
+outsl(uint32_t port, const void *addr, int cnt) {
+    asm volatile (
+        "cld;"
+        "repne; outsl;"
+        : "=S" (addr), "=c" (cnt)
+        : "d" (port), "0" (addr), "1" (cnt)
+        : "memory", "cc");
+}
+
+static inline uint32_t
+read_ebp(void) {
+    uint32_t ebp;
+    asm volatile ("movl %%ebp, %0" : "=r" (ebp));
+    return ebp;
+}
+
+static inline void
+breakpoint(void) {
+    asm volatile ("int $3");
+}
+
+static inline uint32_t
+read_dr(unsigned regnum) {
+    uint32_t value = 0;
+    switch (regnum) {
+    case 0: asm volatile ("movl %%db0, %0" : "=r" (value)); break;
+    case 1: asm volatile ("movl %%db1, %0" : "=r" (value)); break;
+    case 2: asm volatile ("movl %%db2, %0" : "=r" (value)); break;
+    case 3: asm volatile ("movl %%db3, %0" : "=r" (value)); break;
+    case 6: asm volatile ("movl %%db6, %0" : "=r" (value)); break;
+    case 7: asm volatile ("movl %%db7, %0" : "=r" (value)); break;
+    }
+    return value;
+}
+
+static void
+write_dr(unsigned regnum, uint32_t value) {
+    switch (regnum) {
+    case 0: asm volatile ("movl %0, %%db0" :: "r" (value)); break;
+    case 1: asm volatile ("movl %0, %%db1" :: "r" (value)); break;
+    case 2: asm volatile ("movl %0, %%db2" :: "r" (value)); break;
+    case 3: asm volatile ("movl %0, %%db3" :: "r" (value)); break;
+    case 6: asm volatile ("movl %0, %%db6" :: "r" (value)); break;
+    case 7: asm volatile ("movl %0, %%db7" :: "r" (value)); break;
+    }
+}
+
+static inline void
+lidt(struct pseudodesc *pd) {
+    asm volatile ("lidt (%0)" :: "r" (pd) : "memory");
+}
+
+static inline void
+sti(void) {
+    asm volatile ("sti");
+}
+
+static inline void
+cli(void) {
+    asm volatile ("cli" ::: "memory");
+}
+
+static inline void
+ltr(uint16_t sel) {
+    asm volatile ("ltr %0" :: "r" (sel) : "memory");
+}
+
+static inline uint32_t
+read_eflags(void) {
+    uint32_t eflags;
+    asm volatile ("pushfl; popl %0" : "=r" (eflags));
+    return eflags;
+}
+
+static inline void
+write_eflags(uint32_t eflags) {
+    asm volatile ("pushl %0; popfl" :: "r" (eflags));
+}
+
+static inline void
+lcr0(uintptr_t cr0) {
+    asm volatile ("mov %0, %%cr0" :: "r" (cr0) : "memory");
+}
+
+static inline void
+lcr3(uintptr_t cr3) {
+    asm volatile ("mov %0, %%cr3" :: "r" (cr3) : "memory");
+}
+
+static inline uintptr_t
+rcr0(void) {
+    uintptr_t cr0;
+    asm volatile ("mov %%cr0, %0" : "=r" (cr0) :: "memory");
+    return cr0;
+}
+
+static inline uintptr_t
+rcr1(void) {
+    uintptr_t cr1;
+    asm volatile ("mov %%cr1, %0" : "=r" (cr1) :: "memory");
+    return cr1;
+}
+
+static inline uintptr_t
+rcr2(void) {
+    uintptr_t cr2;
+    asm volatile ("mov %%cr2, %0" : "=r" (cr2) :: "memory");
+    return cr2;
+}
+
+static inline uintptr_t
+rcr3(void) {
+    uintptr_t cr3;
+    asm volatile ("mov %%cr3, %0" : "=r" (cr3) :: "memory");
+    return cr3;
+}
+
+static inline void
+invlpg(void *addr) {
+    asm volatile ("invlpg (%0)" :: "r" (addr) : "memory");
+}
+
+static inline int __strcmp(const char *s1, const char *s2) __attribute__((always_inline));
+static inline char *__strcpy(char *dst, const char *src) __attribute__((always_inline));
+static inline void *__memset(void *s, char c, size_t n) __attribute__((always_inline));
+static inline void *__memmove(void *dst, const void *src, size_t n) __attribute__((always_inline));
+static inline void *__memcpy(void *dst, const void *src, size_t n) __attribute__((always_inline));
+
+#ifndef __HAVE_ARCH_STRCMP
+#define __HAVE_ARCH_STRCMP
+static inline int
+__strcmp(const char *s1, const char *s2) {
+    int d0, d1, ret;
+    asm volatile (
+        "1: lodsb;"
+        "scasb;"
+        "jne 2f;"
+        "testb %%al, %%al;"
+        "jne 1b;"
+        "xorl %%eax, %%eax;"
+        "jmp 3f;"
+        "2: sbbl %%eax, %%eax;"
+        "orb $1, %%al;"
+        "3:"
+        : "=a" (ret), "=&S" (d0), "=&D" (d1)
+        : "1" (s1), "2" (s2)
+        : "memory");
+    return ret;
+}
+
+#endif /* __HAVE_ARCH_STRCMP */
+
+#ifndef __HAVE_ARCH_STRCPY
+#define __HAVE_ARCH_STRCPY
+static inline char *
+__strcpy(char *dst, const char *src) {
+    int d0, d1, d2;
+    asm volatile (
+        "1: lodsb;"
+        "stosb;"
+        "testb %%al, %%al;"
+        "jne 1b;"
+        : "=&S" (d0), "=&D" (d1), "=&a" (d2)
+        : "0" (src), "1" (dst) : "memory");
+    return dst;
+}
+#endif /* __HAVE_ARCH_STRCPY */
+
+#ifndef __HAVE_ARCH_MEMSET
+#define __HAVE_ARCH_MEMSET
+static inline void *
+__memset(void *s, char c, size_t n) {
+    int d0, d1;
+    asm volatile (
+        "rep; stosb;"
+        : "=&c" (d0), "=&D" (d1)
+        : "0" (n), "a" (c), "1" (s)
+        : "memory");
+    return s;
+}
+#endif /* __HAVE_ARCH_MEMSET */
+
+#ifndef __HAVE_ARCH_MEMMOVE
+#define __HAVE_ARCH_MEMMOVE
+static inline void *
+__memmove(void *dst, const void *src, size_t n) {
+    if (dst < src) {
+        return __memcpy(dst, src, n);
+    }
+    int d0, d1, d2;
+    asm volatile (
+        "std;"
+        "rep; movsb;"
+        "cld;"
+        : "=&c" (d0), "=&S" (d1), "=&D" (d2)
+        : "0" (n), "1" (n - 1 + src), "2" (n - 1 + dst)
+        : "memory");
+    return dst;
+}
+#endif /* __HAVE_ARCH_MEMMOVE */
+
+#ifndef __HAVE_ARCH_MEMCPY
+#define __HAVE_ARCH_MEMCPY
+static inline void *
+__memcpy(void *dst, const void *src, size_t n) {
+    int d0, d1, d2;
+    asm volatile (
+        "rep; movsl;"
+        "movl %4, %%ecx;"
+        "andl $3, %%ecx;"
+        "jz 1f;"
+        "rep; movsb;"
+        "1:"
+        : "=&c" (d0), "=&D" (d1), "=&S" (d2)
+        : "0" (n / 4), "g" (n), "1" (dst), "2" (src)
+        : "memory");
+    return dst;
+}
+#endif /* __HAVE_ARCH_MEMCPY */
+
+#endif /* !__LIBS_X86_H__ */
+

labcodes_answer/lab2_result/tools/boot.ld

@@ -0,0 +1,15 @@
+OUTPUT_FORMAT("elf32-i386")
+OUTPUT_ARCH(i386)
+
+SECTIONS {
+    . = 0x7C00;
+
+    .startup : {
+        *bootasm.o(.text)
+    }
+
+    .text : { *(.text) }
+    .data : { *(.data .rodata) }
+    
+    /DISCARD/ : { *(.eh_*) }
+}

labcodes_answer/lab2_result/tools/function.mk

@@ -0,0 +1,95 @@
+OBJPREFIX	:= __objs_
+
+.SECONDEXPANSION:
+# -------------------- function begin --------------------
+
+# list all files in some directories: (#directories, #types)
+listf = $(filter $(if $(2),$(addprefix %.,$(2)),%),\
+		  $(wildcard $(addsuffix $(SLASH)*,$(1))))
+
+# get .o obj files: (#files[, packet])
+toobj = $(addprefix $(OBJDIR)$(SLASH)$(if $(2),$(2)$(SLASH)),\
+		$(addsuffix .o,$(basename $(1))))
+
+# get .d dependency files: (#files[, packet])
+todep = $(patsubst %.o,%.d,$(call toobj,$(1),$(2)))
+
+totarget = $(addprefix $(BINDIR)$(SLASH),$(1))
+
+# change $(name) to $(OBJPREFIX)$(name): (#names)
+packetname = $(if $(1),$(addprefix $(OBJPREFIX),$(1)),$(OBJPREFIX))
+
+# cc compile template, generate rule for dep, obj: (file, cc[, flags, dir])
+define cc_template
+$$(call todep,$(1),$(4)): $(1) | $$$$(dir $$$$@)
+	@$(2) -I$$(dir $(1)) $(3) -MM $$< -MT "$$(patsubst %.d,%.o,$$@) $$@"> $$@
+$$(call toobj,$(1),$(4)): $(1) | $$$$(dir $$$$@)
+	@echo + cc $$<
+	$(V)$(2) -I$$(dir $(1)) $(3) -c $$< -o $$@
+ALLOBJS += $$(call toobj,$(1),$(4))
+endef
+
+# compile file: (#files, cc[, flags, dir])
+define do_cc_compile
+$$(foreach f,$(1),$$(eval $$(call cc_template,$$(f),$(2),$(3),$(4))))
+endef
+
+# add files to packet: (#files, cc[, flags, packet, dir])
+define do_add_files_to_packet
+__temp_packet__ := $(call packetname,$(4))
+ifeq ($$(origin $$(__temp_packet__)),undefined)
+$$(__temp_packet__) :=
+endif
+__temp_objs__ := $(call toobj,$(1),$(5))
+$$(foreach f,$(1),$$(eval $$(call cc_template,$$(f),$(2),$(3),$(5))))
+$$(__temp_packet__) += $$(__temp_objs__)
+endef
+
+# add objs to packet: (#objs, packet)
+define do_add_objs_to_packet
+__temp_packet__ := $(call packetname,$(2))
+ifeq ($$(origin $$(__temp_packet__)),undefined)
+$$(__temp_packet__) :=
+endif
+$$(__temp_packet__) += $(1)
+endef
+
+# add packets and objs to target (target, #packes, #objs[, cc, flags])
+define do_create_target
+__temp_target__ = $(call totarget,$(1))
+__temp_objs__ = $$(foreach p,$(call packetname,$(2)),$$($$(p))) $(3)
+TARGETS += $$(__temp_target__)
+ifneq ($(4),)
+$$(__temp_target__): $$(__temp_objs__) | $$$$(dir $$$$@)
+	$(V)$(4) $(5) $$^ -o $$@
+else
+$$(__temp_target__): $$(__temp_objs__) | $$$$(dir $$$$@)
+endif
+endef
+
+# finish all
+define do_finish_all
+ALLDEPS = $$(ALLOBJS:.o=.d)
+$$(sort $$(dir $$(ALLOBJS)) $(BINDIR)$(SLASH) $(OBJDIR)$(SLASH)):
+	@$(MKDIR) $$@
+endef
+
+# --------------------  function end  --------------------
+# compile file: (#files, cc[, flags, dir])
+cc_compile = $(eval $(call do_cc_compile,$(1),$(2),$(3),$(4)))
+
+# add files to packet: (#files, cc[, flags, packet, dir])
+add_files = $(eval $(call do_add_files_to_packet,$(1),$(2),$(3),$(4),$(5)))
+
+# add objs to packet: (#objs, packet)
+add_objs = $(eval $(call do_add_objs_to_packet,$(1),$(2)))
+
+# add packets and objs to target (target, #packes, #objs, cc, [, flags])
+create_target = $(eval $(call do_create_target,$(1),$(2),$(3),$(4),$(5)))
+
+read_packet = $(foreach p,$(call packetname,$(1)),$($(p)))
+
+add_dependency = $(eval $(1): $(2))
+
+finish_all = $(eval $(call do_finish_all))
+

labcodes_answer/lab2_result/tools/gdbinit

@@ -0,0 +1,3 @@
+file bin/kernel
+target remote :1234
+break kern_init

labcodes_answer/lab2_result/tools/grade.sh

@@ -0,0 +1,340 @@
+#!/bin/sh
+
+verbose=false
+if [ "x$1" = "x-v" ]; then
+    verbose=true
+    out=/dev/stdout
+    err=/dev/stderr
+else
+    out=/dev/null
+    err=/dev/null
+fi
+
+## make & makeopts
+if gmake --version > /dev/null 2>&1; then
+    make=gmake;
+else
+    make=make;
+fi
+
+makeopts="--quiet --no-print-directory -j"
+
+make_print() {
+    echo `$make $makeopts print-$1`
+}
+
+## command tools
+awk='awk'
+bc='bc'
+date='date'
+grep='grep'
+rm='rm -f'
+sed='sed'
+
+## symbol table
+sym_table='obj/kernel.sym'
+
+## gdb & gdbopts
+gdb="$(make_print GDB)"
+gdbport='1234'
+
+gdb_in="$(make_print GRADE_GDB_IN)"
+
+## qemu & qemuopts
+qemu="$(make_print qemu)"
+
+qemu_out="$(make_print GRADE_QEMU_OUT)"
+
+if $qemu -nographic -help | grep -q '^-gdb'; then
+    qemugdb="-gdb tcp::$gdbport"
+else
+    qemugdb="-s -p $gdbport"
+fi
+
+## default variables
+default_timeout=30
+default_pts=5
+
+pts=5
+part=0
+part_pos=0
+total=0
+total_pos=0
+
+## default functions
+update_score() {
+    total=`expr $total + $part`
+    total_pos=`expr $total_pos + $part_pos`
+    part=0
+    part_pos=0
+}
+
+get_time() {
+    echo `$date +%s.%N 2> /dev/null`
+}
+
+show_part() {
+    echo "Part $1 Score: $part/$part_pos"
+    echo
+    update_score
+}
+
+show_final() {
+    update_score
+    echo "Total Score: $total/$total_pos"
+    if [ $total -lt $total_pos ]; then
+        exit 1
+    fi
+}
+
+show_time() {
+    t1=$(get_time)
+    time=`echo "scale=1; ($t1-$t0)/1" | $sed 's/.N/.0/g' | $bc 2> /dev/null`
+    echo "(${time}s)"
+}
+
+show_build_tag() {
+    echo "$1:" | $awk '{printf "%-24s ", $0}'
+}
+
+show_check_tag() {
+    echo "$1:" | $awk '{printf "  -%-40s  ", $0}'
+}
+
+show_msg() {
+    echo $1
+    shift
+    if [ $# -gt 0 ]; then
+        echo "$@" | awk '{printf "   %s\n", $0}'
+        echo
+    fi
+}
+
+pass() {
+    show_msg OK "$@"
+    part=`expr $part + $pts`
+    part_pos=`expr $part_pos + $pts`
+}
+
+fail() {
+    show_msg WRONG "$@"
+    part_pos=`expr $part_pos + $pts`
+}
+
+run_qemu() {
+    # Run qemu with serial output redirected to $qemu_out. If $brkfun is non-empty,
+    # wait until $brkfun is reached or $timeout expires, then kill QEMU
+    qemuextra=
+    if [ "$brkfun" ]; then
+        qemuextra="-S $qemugdb"
+    fi
+
+    if [ -z "$timeout" ] || [ $timeout -le 0 ]; then
+        timeout=$default_timeout;
+    fi
+
+    t0=$(get_time)
+    (
+        ulimit -t $timeout
+        exec $qemu -nographic $qemuopts -serial file:$qemu_out -monitor null -no-reboot $qemuextra
+    ) > $out 2> $err &
+    pid=$!
+
+    # wait for QEMU to start
+    sleep 1
+
+    if [ -n "$brkfun" ]; then
+        # find the address of the kernel $brkfun function
+        brkaddr=`$grep " $brkfun\$" $sym_table | $sed -e's/ .*$//g'`
+        (
+            echo "target remote localhost:$gdbport"
+            echo "break *0x$brkaddr"
+            echo "continue"
+        ) > $gdb_in
+
+        $gdb -batch -nx -x $gdb_in > /dev/null 2>&1
+
+        # make sure that QEMU is dead
+        # on OS X, exiting gdb doesn't always exit qemu
+        kill $pid > /dev/null 2>&1
+    fi
+}
+
+build_run() {
+    # usage: build_run <tag> <args>
+    show_build_tag "$1"
+    shift
+
+    if $verbose; then
+        echo "$make $@ ..."
+    fi
+    $make $makeopts $@ 'DEFS+=-DDEBUG_GRADE' > $out 2> $err
+
+    if [ $? -ne 0 ]; then
+        echo $make $@ failed
+        exit 1
+    fi
+
+    # now run qemu and save the output
+    run_qemu
+
+    show_time
+}
+
+check_result() {
+    # usage: check_result <tag> <check> <check args...>
+    show_check_tag "$1"
+    shift
+
+    # give qemu some time to run (for asynchronous mode)
+    if [ ! -s $qemu_out ]; then
+        sleep 4
+    fi
+
+    if [ ! -s $qemu_out ]; then
+        fail > /dev/null
+        echo 'no $qemu_out'
+    else
+        check=$1
+        shift
+        $check "$@"
+    fi
+}
+
+check_regexps() {
+    okay=yes
+    not=0
+    reg=0
+    error=
+    for i do
+        if [ "x$i" = "x!" ]; then
+            not=1
+        elif [ "x$i" = "x-" ]; then
+            reg=1
+        else
+            if [ $reg -ne 0 ]; then
+                $grep '-E' "^$i\$" $qemu_out > /dev/null
+            else
+                $grep '-F' "$i" $qemu_out > /dev/null
+            fi
+            found=$(($? == 0))
+            if [ $found -eq $not ]; then
+                if [ $found -eq 0 ]; then
+                    msg="!! error: missing '$i'"
+                else
+                    msg="!! error: got unexpected line '$i'"
+                fi
+                okay=no
+                if [ -z "$error" ]; then
+                    error="$msg"
+                else
+                    error="$error\n$msg"
+                fi
+            fi
+            not=0
+            reg=0
+        fi
+    done
+    if [ "$okay" = "yes" ]; then
+        pass
+    else
+        fail "$error"
+        if $verbose; then
+            exit 1
+        fi
+    fi
+}
+
+run_test() {
+    # usage: run_test [-tag <tag>] [-Ddef...] [-check <check>] checkargs ...
+    tag=
+    check=check_regexps
+    while true; do
+        select=
+        case $1 in
+            -tag)
+                select=`expr substr $1 2 ${#1}`
+                eval $select='$2'
+                ;;
+        esac
+        if [ -z "$select" ]; then
+            break
+        fi
+        shift
+        shift
+    done
+    defs=
+    while expr "x$1" : "x-D.*" > /dev/null; do
+        defs="DEFS+='$1' $defs"
+        shift
+    done
+    if [ "x$1" = "x-check" ]; then
+        check=$2
+        shift
+        shift
+    fi
+
+    $make $makeopts touch > /dev/null 2>&1
+    build_run "$tag" "$defs"
+
+    check_result 'check result' "$check" "$@"
+}
+
+quick_run() {
+    # usage: quick_run <tag> [-Ddef...]
+    tag="$1"
+    shift
+    defs=
+    while expr "x$1" : "x-D.*" > /dev/null; do
+        defs="DEFS+='$1' $defs"
+        shift
+    done
+
+    $make $makeopts touch > /dev/null 2>&1
+    build_run "$tag" "$defs"
+}
+
+quick_check() {
+    # usage: quick_check <tag> checkargs ...
+    tag="$1"
+    shift
+    check_result "$tag" check_regexps "$@"
+}
+
+## kernel image
+osimg=$(make_print ucoreimg)
+
+## set default qemu-options
+qemuopts="-hda $osimg"
+
+## set break-function, default is readline
+brkfun=readline
+
+## check now!!
+
+quick_run 'Check PMM'
+
+pts=20
+quick_check 'check pmm'                                         \
+    'memory management: default_pmm_manager'                     \
+    'check_alloc_page() succeeded!'                             \
+    'check_pgdir() succeeded!'                                  \
+    'check_boot_pgdir() succeeded!'
+
+pts=20
+quick_check 'check page table'                                  \
+    'PDE(0e0) c0000000-f8000000 38000000 urw'                   \
+    '  |-- PTE(38000) c0000000-f8000000 38000000 -rw'           \
+    'PDE(001) fac00000-fb000000 00400000 -rw'                   \
+    '  |-- PTE(000e0) faf00000-fafe0000 000e0000 urw'           \
+    '  |-- PTE(00001) fafeb000-fafec000 00001000 -rw'
+
+pts=10
+quick_check 'check ticks'                                       \
+    '++ setup timer interrupts'                                 \
+    '100 ticks'                                                 \
+    'End of Test.'
+
+## print final-score
+show_final
+

labcodes_answer/lab2_result/tools/kernel.ld

@@ -0,0 +1,58 @@
+/* Simple linker script for the ucore kernel.
+   See the GNU ld 'info' manual ("info ld") to learn the syntax. */
+
+OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
+OUTPUT_ARCH(i386)
+ENTRY(kern_entry)
+
+SECTIONS {
+    /* Load the kernel at this address: "." means the current address */
+    . = 0xC0100000;
+
+    .text : {
+        *(.text .stub .text.* .gnu.linkonce.t.*)
+    }
+
+    PROVIDE(etext = .); /* Define the 'etext' symbol to this value */
+
+    .rodata : {
+        *(.rodata .rodata.* .gnu.linkonce.r.*)
+    }
+
+    /* Include debugging information in kernel memory */
+    .stab : {
+        PROVIDE(__STAB_BEGIN__ = .);
+        *(.stab);
+        PROVIDE(__STAB_END__ = .);
+        BYTE(0)     /* Force the linker to allocate space
+                   for this section */
+    }
+
+    .stabstr : {
+        PROVIDE(__STABSTR_BEGIN__ = .);
+        *(.stabstr);
+        PROVIDE(__STABSTR_END__ = .);
+        BYTE(0)     /* Force the linker to allocate space
+                   for this section */
+    }
+
+    /* Adjust the address for the data segment to the next page */
+    . = ALIGN(0x1000);
+
+    /* The data segment */
+    .data : {
+        *(.data)
+    }
+
+    PROVIDE(edata = .);
+
+    .bss : {
+        *(.bss)
+    }
+
+    PROVIDE(end = .);
+
+    /DISCARD/ : {
+        *(.eh_frame .note.GNU-stack)
+    }
+}

labcodes_answer/lab2_result/tools/sign.c

@@ -0,0 +1,43 @@
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/stat.h>
+
+int
+main(int argc, char *argv[]) {
+    struct stat st;
+    if (argc != 3) {
+        fprintf(stderr, "Usage: <input filename> <output filename>\n");
+        return -1;
+    }
+    if (stat(argv[1], &st) != 0) {
+        fprintf(stderr, "Error opening file '%s': %s\n", argv[1], strerror(errno));
+        return -1;
+    }
+    printf("'%s' size: %lld bytes\n", argv[1], (long long)st.st_size);
+    if (st.st_size > 510) {
+        fprintf(stderr, "%lld >> 510!!\n", (long long)st.st_size);
+        return -1;
+    }
+    char buf[512];
+    memset(buf, 0, sizeof(buf));
+    FILE *ifp = fopen(argv[1], "rb");
+    int size = fread(buf, 1, st.st_size, ifp);
+    if (size != st.st_size) {
+        fprintf(stderr, "read '%s' error, size is %d.\n", argv[1], size);
+        return -1;
+    }
+    fclose(ifp);
+    buf[510] = 0x55;
+    buf[511] = 0xAA;
+    FILE *ofp = fopen(argv[2], "wb+");
+    size = fwrite(buf, 1, 512, ofp);
+    if (size != 512) {
+        fprintf(stderr, "write '%s' error, size is %d.\n", argv[2], size);
+        return -1;
+    }
+    fclose(ofp);
+    printf("build 512 bytes boot sector: '%s' success!\n", argv[2]);
+    return 0;
+}
+

labcodes_answer/lab2_result/tools/vector.c

@@ -0,0 +1,29 @@
+#include <stdio.h>
+
+int
+main(void) {
+    printf("# handler\n");
+    printf(".text\n");
+    printf(".globl __alltraps\n");
+
+    int i;
+    for (i = 0; i < 256; i ++) {
+        printf(".globl vector%d\n", i);
+        printf("vector%d:\n", i);
+        if ((i < 8 || i > 14) && i != 17) {
+            printf("  pushl $0\n");
+        }
+        printf("  pushl $%d\n", i);
+        printf("  jmp __alltraps\n");
+    }
+    printf("\n");
+    printf("# vector table\n");
+    printf(".data\n");
+    printf(".globl __vectors\n");
+    printf("__vectors:\n");
+    for (i = 0; i < 256; i ++) {
+        printf("  .long vector%d\n", i);
+    }
+    return 0;
+}
+

labcodes_answer/lab3_result/Makefile

@@ -0,0 +1,271 @@
+PROJ	:= 8
+EMPTY	:=
+SPACE	:= $(EMPTY) $(EMPTY)
+SLASH	:= /
+
+V       := @
+
+# try to infer the correct GCCPREFX
+ifndef GCCPREFIX
+GCCPREFIX := $(shell if i386-ucore-elf-objdump -i 2>&1 | grep '^elf32-i386$$' >/dev/null 2>&1; \
+	then echo 'i386-ucore-elf-'; \
+	elif objdump -i 2>&1 | grep 'elf32-i386' >/dev/null 2>&1; \
+	then echo ''; \
+	else echo "***" 1>&2; \
+	echo "*** Error: Couldn't find an i386-ucore-elf version of GCC/binutils." 1>&2; \
+	echo "*** Is the directory with i386-ucore-elf-gcc in your PATH?" 1>&2; \
+	echo "*** If your i386-ucore-elf toolchain is installed with a command" 1>&2; \
+	echo "*** prefix other than 'i386-ucore-elf-', set your GCCPREFIX" 1>&2; \
+	echo "*** environment variable to that prefix and run 'make' again." 1>&2; \
+	echo "*** To turn off this error, run 'gmake GCCPREFIX= ...'." 1>&2; \
+	echo "***" 1>&2; exit 1; fi)
+endif
+
+# try to infer the correct QEMU
+ifndef QEMU
+QEMU := $(shell if which qemu > /dev/null; \
+	then echo 'qemu'; exit; \
+	elif which i386-ucore-elf-qemu > /dev/null; \
+	then echo 'i386-ucore-elf-qemu'; exit; \
+	else \
+	echo "***" 1>&2; \
+	echo "*** Error: Couldn't find a working QEMU executable." 1>&2; \
+	echo "*** Is the directory containing the qemu binary in your PATH" 1>&2; \
+	echo "***" 1>&2; exit 1; fi)
+endif
+
+# eliminate default suffix rules
+.SUFFIXES: .c .S .h
+
+# delete target files if there is an error (or make is interrupted)
+.DELETE_ON_ERROR:
+
+# define compiler and flags
+
+HOSTCC		:= gcc
+HOSTCFLAGS	:= -g -Wall -O2
+
+GDB		:= $(GCCPREFIX)gdb
+
+CC		?= $(GCCPREFIX)gcc
+CFLAGS	:= -fno-builtin -Wall -ggdb -m32 -gstabs -nostdinc $(DEFS)
+CFLAGS	+= $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector)
+CTYPE	:= c S
+
+LD      := $(GCCPREFIX)ld
+LDFLAGS	:= -m $(shell $(LD) -V | grep elf_i386 2>/dev/null)
+LDFLAGS	+= -nostdlib
+
+OBJCOPY := $(GCCPREFIX)objcopy
+OBJDUMP := $(GCCPREFIX)objdump
+
+COPY	:= cp
+MKDIR   := mkdir -p
+MV		:= mv
+RM		:= rm -f
+AWK		:= awk
+SED		:= sed
+SH		:= sh
+TR		:= tr
+TOUCH	:= touch -c
+
+OBJDIR	:= obj
+BINDIR	:= bin
+
+ALLOBJS	:=
+ALLDEPS	:=
+TARGETS	:=
+
+include tools/function.mk
+
+listf_cc = $(call listf,$(1),$(CTYPE))
+
+# for cc
+add_files_cc = $(call add_files,$(1),$(CC),$(CFLAGS) $(3),$(2),$(4))
+create_target_cc = $(call create_target,$(1),$(2),$(3),$(CC),$(CFLAGS))
+
+# for hostcc
+add_files_host = $(call add_files,$(1),$(HOSTCC),$(HOSTCFLAGS),$(2),$(3))
+create_target_host = $(call create_target,$(1),$(2),$(3),$(HOSTCC),$(HOSTCFLAGS))
+
+cgtype = $(patsubst %.$(2),%.$(3),$(1))
+objfile = $(call toobj,$(1))
+asmfile = $(call cgtype,$(call toobj,$(1)),o,asm)
+outfile = $(call cgtype,$(call toobj,$(1)),o,out)
+symfile = $(call cgtype,$(call toobj,$(1)),o,sym)
+
+# for match pattern
+match = $(shell echo $(2) | $(AWK) '{for(i=1;i<=NF;i++){if(match("$(1)","^"$$(i)"$$")){exit 1;}}}'; echo $$?)
+
+# >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
+# include kernel/user
+
+INCLUDE	+= libs/
+
+CFLAGS	+= $(addprefix -I,$(INCLUDE))
+
+LIBDIR	+= libs
+
+$(call add_files_cc,$(call listf_cc,$(LIBDIR)),libs,)
+
+# -------------------------------------------------------------------
+# kernel
+
+KINCLUDE	+= kern/debug/ \
+			   kern/driver/ \
+			   kern/trap/ \
+			   kern/mm/ \
+			   kern/libs/ \
+			   kern/sync/ \
+			   kern/fs/
+
+KSRCDIR		+= kern/init \
+			   kern/libs \
+			   kern/debug \
+			   kern/driver \
+			   kern/trap \
+			   kern/mm \
+			   kern/sync \
+			   kern/fs
+
+KCFLAGS		+= $(addprefix -I,$(KINCLUDE))
+
+$(call add_files_cc,$(call listf_cc,$(KSRCDIR)),kernel,$(KCFLAGS))
+
+KOBJS	= $(call read_packet,kernel libs)
+
+# create kernel target
+kernel = $(call totarget,kernel)
+
+$(kernel): tools/kernel.ld
+
+$(kernel): $(KOBJS)
+	@echo + ld $@
+	$(V)$(LD) $(LDFLAGS) -T tools/kernel.ld -o $@ $(KOBJS)
+	@$(OBJDUMP) -S $@ > $(call asmfile,kernel)
+	@$(OBJDUMP) -t $@ | $(SED) '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > $(call symfile,kernel)
+
+$(call create_target,kernel)
+
+# -------------------------------------------------------------------
+
+# create bootblock
+bootfiles = $(call listf_cc,boot)
+$(foreach f,$(bootfiles),$(call cc_compile,$(f),$(CC),$(CFLAGS) -Os -nostdinc))
+
+bootblock = $(call totarget,bootblock)
+
+$(bootblock): $(call toobj,boot/bootasm.S) $(call toobj,$(bootfiles)) | $(call totarget,sign)
+	@echo + ld $@
+	$(V)$(LD) $(LDFLAGS) -N -T tools/boot.ld $^ -o $(call toobj,bootblock)
+	@$(OBJDUMP) -S $(call objfile,bootblock) > $(call asmfile,bootblock)
+	@$(OBJCOPY) -S -O binary $(call objfile,bootblock) $(call outfile,bootblock)
+	@$(call totarget,sign) $(call outfile,bootblock) $(bootblock)
+
+$(call create_target,bootblock)
+
+# -------------------------------------------------------------------
+
+# create 'sign' tools
+$(call add_files_host,tools/sign.c,sign,sign)
+$(call create_target_host,sign,sign)
+
+# -------------------------------------------------------------------
+
+# create ucore.img
+UCOREIMG	:= $(call totarget,ucore.img)
+
+$(UCOREIMG): $(kernel) $(bootblock)
+	$(V)dd if=/dev/zero of=$@ count=10000
+	$(V)dd if=$(bootblock) of=$@ conv=notrunc
+	$(V)dd if=$(kernel) of=$@ seek=1 conv=notrunc
+
+$(call create_target,ucore.img)
+
+# -------------------------------------------------------------------
+
+# create swap.img
+SWAPIMG		:= $(call totarget,swap.img)
+
+$(SWAPIMG):
+	$(V)dd if=/dev/zero of=$@ bs=1M count=128
+
+$(call create_target,swap.img)
+
+# >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
+
+$(call finish_all)
+
+IGNORE_ALLDEPS	= clean \
+				  dist-clean \
+				  grade \
+				  touch \
+				  print-.+ \
+				  handin
+
+ifeq ($(call match,$(MAKECMDGOALS),$(IGNORE_ALLDEPS)),0)
+-include $(ALLDEPS)
+endif
+
+# files for grade script
+
+TARGETS: $(TARGETS)
+
+.DEFAULT_GOAL := TARGETS
+
+QEMUOPTS = -hda $(UCOREIMG) -drive file=$(SWAPIMG),media=disk,cache=writeback
+
+.PHONY: qemu qemu-nox debug debug-nox
+qemu: $(UCOREIMG) $(SWAPIMG)
+	$(V)$(QEMU) -parallel stdio $(QEMUOPTS) -serial null
+
+qemu-nox: $(UCOREIMG) $(SWAPIMG)
+	$(V)$(QEMU) -serial mon:stdio $(QEMUOPTS) -nographic
+
+TERMINAL := gnome-terminal
+
+debug: $(UCOREIMG) $(SWAPIMG)
+	$(V)$(QEMU) -S -s -parallel stdio $(QEMUOPTS) -serial null &
+	$(V)sleep 2
+	$(V)$(TERMINAL) -e "$(GDB) -q -x tools/gdbinit"
+
+debug-nox: $(UCOREIMG) $(SWAPIMG)
+	$(V)$(QEMU) -S -s -serial mon:stdio $(QEMUOPTS) -nographic &
+	$(V)sleep 2
+	$(V)$(TERMINAL) -e "$(GDB) -q -x tools/gdbinit"
+
+.PHONY: grade touch
+
+GRADE_GDB_IN	:= .gdb.in
+GRADE_QEMU_OUT	:= .qemu.out
+HANDIN			:= proj$(PROJ)-handin.tar.gz
+
+TOUCH_FILES		:= kern/trap/trap.c
+
+MAKEOPTS		:= --quiet --no-print-directory
+
+grade:
+	$(V)$(MAKE) $(MAKEOPTS) clean
+	$(V)$(SH) tools/grade.sh
+
+touch:
+	$(V)$(foreach f,$(TOUCH_FILES),$(TOUCH) $(f))
+
+print-%:
+	@echo $($(shell echo $(patsubst print-%,%,$@) | $(TR) [a-z] [A-Z]))
+
+.PHONY: clean dist-clean handin packall
+clean:
+	$(V)$(RM) $(GRADE_GDB_IN) $(GRADE_QEMU_OUT)
+	-$(RM) -r $(OBJDIR) $(BINDIR)
+
+dist-clean: clean
+	-$(RM) $(HANDIN)
+
+handin: packall
+	@echo Please visit http://learn.tsinghua.edu.cn and upload $(HANDIN). Thanks!
+
+packall: clean
+	@$(RM) -f $(HANDIN)
+	@tar -czf $(HANDIN) `find . -type f -o -type d | grep -v '^\.*$$' | grep -vF '$(HANDIN)'`
+