《操作系统》的实验代码。
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#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__ */