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372 lines
13 KiB
372 lines
13 KiB
#include <proc.h>
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#include <kmalloc.h>
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#include <string.h>
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#include <sync.h>
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#include <pmm.h>
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#include <error.h>
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#include <sched.h>
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#include <elf.h>
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#include <vmm.h>
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#include <trap.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <assert.h>
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/* ------------- process/thread mechanism design&implementation -------------
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(an simplified Linux process/thread mechanism )
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introduction:
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ucore implements a simple process/thread mechanism. process contains the independent memory sapce, at least one threads
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for execution, the kernel data(for management), processor state (for context switch), files(in lab6), etc. ucore needs to
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manage all these details efficiently. In ucore, a thread is just a special kind of process(share process's memory).
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------------------------------
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process state : meaning -- reason
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PROC_UNINIT : uninitialized -- alloc_proc
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PROC_SLEEPING : sleeping -- try_free_pages, do_wait, do_sleep
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PROC_RUNNABLE : runnable(maybe running) -- proc_init, wakeup_proc,
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PROC_ZOMBIE : almost dead -- do_exit
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-----------------------------
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process state changing:
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alloc_proc RUNNING
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+ +--<----<--+
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+ + proc_run +
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V +-->---->--+
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PROC_UNINIT -- proc_init/wakeup_proc --> PROC_RUNNABLE -- try_free_pages/do_wait/do_sleep --> PROC_SLEEPING --
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A + +
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| +--- do_exit --> PROC_ZOMBIE +
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+ +
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-----------------------wakeup_proc----------------------------------
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-----------------------------
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process relations
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parent: proc->parent (proc is children)
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children: proc->cptr (proc is parent)
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older sibling: proc->optr (proc is younger sibling)
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younger sibling: proc->yptr (proc is older sibling)
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-----------------------------
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related syscall for process:
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SYS_exit : process exit, -->do_exit
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SYS_fork : create child process, dup mm -->do_fork-->wakeup_proc
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SYS_wait : wait process -->do_wait
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SYS_exec : after fork, process execute a program -->load a program and refresh the mm
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SYS_clone : create child thread -->do_fork-->wakeup_proc
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SYS_yield : process flag itself need resecheduling, -- proc->need_sched=1, then scheduler will rescheule this process
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SYS_sleep : process sleep -->do_sleep
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SYS_kill : kill process -->do_kill-->proc->flags |= PF_EXITING
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-->wakeup_proc-->do_wait-->do_exit
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SYS_getpid : get the process's pid
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*/
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// the process set's list
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list_entry_t proc_list;
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#define HASH_SHIFT 10
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#define HASH_LIST_SIZE (1 << HASH_SHIFT)
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#define pid_hashfn(x) (hash32(x, HASH_SHIFT))
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// has list for process set based on pid
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static list_entry_t hash_list[HASH_LIST_SIZE];
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// idle proc
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struct proc_struct *idleproc = NULL;
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// init proc
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struct proc_struct *initproc = NULL;
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// current proc
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struct proc_struct *current = NULL;
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static int nr_process = 0;
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void kernel_thread_entry(void);
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void forkrets(struct trapframe *tf);
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void switch_to(struct context *from, struct context *to);
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// alloc_proc - alloc a proc_struct and init all fields of proc_struct
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static struct proc_struct *
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alloc_proc(void) {
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struct proc_struct *proc = kmalloc(sizeof(struct proc_struct));
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if (proc != NULL) {
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//LAB4:EXERCISE1 YOUR CODE
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/*
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* below fields in proc_struct need to be initialized
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* enum proc_state state; // Process state
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* int pid; // Process ID
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* int runs; // the running times of Proces
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* uintptr_t kstack; // Process kernel stack
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* volatile bool need_resched; // bool value: need to be rescheduled to release CPU?
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* struct proc_struct *parent; // the parent process
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* struct mm_struct *mm; // Process's memory management field
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* struct context context; // Switch here to run process
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* struct trapframe *tf; // Trap frame for current interrupt
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* uintptr_t cr3; // CR3 register: the base addr of Page Directroy Table(PDT)
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* uint32_t flags; // Process flag
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* char name[PROC_NAME_LEN + 1]; // Process name
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*/
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}
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return proc;
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}
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// set_proc_name - set the name of proc
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char *
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set_proc_name(struct proc_struct *proc, const char *name) {
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memset(proc->name, 0, sizeof(proc->name));
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return memcpy(proc->name, name, PROC_NAME_LEN);
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}
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// get_proc_name - get the name of proc
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char *
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get_proc_name(struct proc_struct *proc) {
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static char name[PROC_NAME_LEN + 1];
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memset(name, 0, sizeof(name));
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return memcpy(name, proc->name, PROC_NAME_LEN);
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}
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// get_pid - alloc a unique pid for process
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static int
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get_pid(void) {
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static_assert(MAX_PID > MAX_PROCESS);
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struct proc_struct *proc;
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list_entry_t *list = &proc_list, *le;
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static int next_safe = MAX_PID, last_pid = MAX_PID;
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if (++ last_pid >= MAX_PID) {
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last_pid = 1;
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goto inside;
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}
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if (last_pid >= next_safe) {
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inside:
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next_safe = MAX_PID;
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repeat:
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le = list;
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while ((le = list_next(le)) != list) {
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proc = le2proc(le, list_link);
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if (proc->pid == last_pid) {
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if (++ last_pid >= next_safe) {
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if (last_pid >= MAX_PID) {
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last_pid = 1;
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}
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next_safe = MAX_PID;
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goto repeat;
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}
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}
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else if (proc->pid > last_pid && next_safe > proc->pid) {
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next_safe = proc->pid;
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}
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}
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}
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return last_pid;
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}
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// proc_run - make process "proc" running on cpu
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// NOTE: before call switch_to, should load base addr of "proc"'s new PDT
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void
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proc_run(struct proc_struct *proc) {
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if (proc != current) {
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bool intr_flag;
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struct proc_struct *prev = current, *next = proc;
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local_intr_save(intr_flag);
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{
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current = proc;
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load_esp0(next->kstack + KSTACKSIZE);
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lcr3(next->cr3);
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switch_to(&(prev->context), &(next->context));
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}
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local_intr_restore(intr_flag);
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}
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}
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// forkret -- the first kernel entry point of a new thread/process
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// NOTE: the addr of forkret is setted in copy_thread function
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// after switch_to, the current proc will execute here.
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static void
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forkret(void) {
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forkrets(current->tf);
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}
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// hash_proc - add proc into proc hash_list
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static void
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hash_proc(struct proc_struct *proc) {
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list_add(hash_list + pid_hashfn(proc->pid), &(proc->hash_link));
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}
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// find_proc - find proc frome proc hash_list according to pid
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struct proc_struct *
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find_proc(int pid) {
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if (0 < pid && pid < MAX_PID) {
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list_entry_t *list = hash_list + pid_hashfn(pid), *le = list;
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while ((le = list_next(le)) != list) {
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struct proc_struct *proc = le2proc(le, hash_link);
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if (proc->pid == pid) {
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return proc;
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}
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}
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}
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return NULL;
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}
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// kernel_thread - create a kernel thread using "fn" function
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// NOTE: the contents of temp trapframe tf will be copied to
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// proc->tf in do_fork-->copy_thread function
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int
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kernel_thread(int (*fn)(void *), void *arg, uint32_t clone_flags) {
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struct trapframe tf;
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memset(&tf, 0, sizeof(struct trapframe));
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tf.tf_cs = KERNEL_CS;
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tf.tf_ds = tf.tf_es = tf.tf_ss = KERNEL_DS;
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tf.tf_regs.reg_ebx = (uint32_t)fn;
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tf.tf_regs.reg_edx = (uint32_t)arg;
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tf.tf_eip = (uint32_t)kernel_thread_entry;
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return do_fork(clone_flags | CLONE_VM, 0, &tf);
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}
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// setup_kstack - alloc pages with size KSTACKPAGE as process kernel stack
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static int
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setup_kstack(struct proc_struct *proc) {
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struct Page *page = alloc_pages(KSTACKPAGE);
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if (page != NULL) {
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proc->kstack = (uintptr_t)page2kva(page);
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return 0;
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}
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return -E_NO_MEM;
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}
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// put_kstack - free the memory space of process kernel stack
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static void
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put_kstack(struct proc_struct *proc) {
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free_pages(kva2page((void *)(proc->kstack)), KSTACKPAGE);
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}
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// copy_mm - process "proc" duplicate OR share process "current"'s mm according clone_flags
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// - if clone_flags & CLONE_VM, then "share" ; else "duplicate"
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static int
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copy_mm(uint32_t clone_flags, struct proc_struct *proc) {
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assert(current->mm == NULL);
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/* do nothing in this project */
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return 0;
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}
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// copy_thread - setup the trapframe on the process's kernel stack top and
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// - setup the kernel entry point and stack of process
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static void
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copy_thread(struct proc_struct *proc, uintptr_t esp, struct trapframe *tf) {
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proc->tf = (struct trapframe *)(proc->kstack + KSTACKSIZE) - 1;
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*(proc->tf) = *tf;
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proc->tf->tf_regs.reg_eax = 0;
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proc->tf->tf_esp = esp;
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proc->tf->tf_eflags |= FL_IF;
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proc->context.eip = (uintptr_t)forkret;
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proc->context.esp = (uintptr_t)(proc->tf);
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}
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/* do_fork - parent process for a new child process
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* @clone_flags: used to guide how to clone the child process
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* @stack: the parent's user stack pointer. if stack==0, It means to fork a kernel thread.
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* @tf: the trapframe info, which will be copied to child process's proc->tf
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*/
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int
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do_fork(uint32_t clone_flags, uintptr_t stack, struct trapframe *tf) {
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int ret = -E_NO_FREE_PROC;
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struct proc_struct *proc;
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if (nr_process >= MAX_PROCESS) {
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goto fork_out;
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}
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ret = -E_NO_MEM;
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//LAB4:EXERCISE2 YOUR CODE
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/*
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* Some Useful MACROs, Functions and DEFINEs, you can use them in below implementation.
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* MACROs or Functions:
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* alloc_proc: create a proc struct and init fields (lab4:exercise1)
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* setup_kstack: alloc pages with size KSTACKPAGE as process kernel stack
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* copy_mm: process "proc" duplicate OR share process "current"'s mm according clone_flags
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* if clone_flags & CLONE_VM, then "share" ; else "duplicate"
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* copy_thread: setup the trapframe on the process's kernel stack top and
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* setup the kernel entry point and stack of process
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* hash_proc: add proc into proc hash_list
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* get_pid: alloc a unique pid for process
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* wakeup_proc: set proc->state = PROC_RUNNABLE
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* VARIABLES:
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* proc_list: the process set's list
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* nr_process: the number of process set
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*/
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// 1. call alloc_proc to allocate a proc_struct
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// 2. call setup_kstack to allocate a kernel stack for child process
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// 3. call copy_mm to dup OR share mm according clone_flag
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// 4. call copy_thread to setup tf & context in proc_struct
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// 5. insert proc_struct into hash_list && proc_list
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// 6. call wakeup_proc to make the new child process RUNNABLE
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// 7. set ret vaule using child proc's pid
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fork_out:
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return ret;
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bad_fork_cleanup_kstack:
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put_kstack(proc);
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bad_fork_cleanup_proc:
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kfree(proc);
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goto fork_out;
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}
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// do_exit - called by sys_exit
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// 1. call exit_mmap & put_pgdir & mm_destroy to free the almost all memory space of process
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// 2. set process' state as PROC_ZOMBIE, then call wakeup_proc(parent) to ask parent reclaim itself.
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// 3. call scheduler to switch to other process
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int
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do_exit(int error_code) {
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panic("process exit!!.\n");
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}
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// init_main - the second kernel thread used to create user_main kernel threads
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static int
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init_main(void *arg) {
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cprintf("this initproc, pid = %d, name = \"%s\"\n", current->pid, get_proc_name(current));
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cprintf("To U: \"%s\".\n", (const char *)arg);
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cprintf("To U: \"en.., Bye, Bye. :)\"\n");
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return 0;
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}
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// proc_init - set up the first kernel thread idleproc "idle" by itself and
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// - create the second kernel thread init_main
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void
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proc_init(void) {
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int i;
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list_init(&proc_list);
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for (i = 0; i < HASH_LIST_SIZE; i ++) {
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list_init(hash_list + i);
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}
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if ((idleproc = alloc_proc()) == NULL) {
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panic("cannot alloc idleproc.\n");
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}
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idleproc->pid = 0;
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idleproc->state = PROC_RUNNABLE;
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idleproc->kstack = (uintptr_t)bootstack;
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idleproc->need_resched = 1;
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set_proc_name(idleproc, "idle");
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nr_process ++;
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current = idleproc;
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int pid = kernel_thread(init_main, "Hello world!!", 0);
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if (pid <= 0) {
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panic("create init_main failed.\n");
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}
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initproc = find_proc(pid);
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set_proc_name(initproc, "init");
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assert(idleproc != NULL && idleproc->pid == 0);
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assert(initproc != NULL && initproc->pid == 1);
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}
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// cpu_idle - at the end of kern_init, the first kernel thread idleproc will do below works
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void
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cpu_idle(void) {
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while (1) {
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if (current->need_resched) {
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schedule();
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}
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}
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}
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