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