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517 lines
16 KiB
517 lines
16 KiB
#include <vmm.h>
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#include <sync.h>
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#include <string.h>
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#include <assert.h>
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#include <stdio.h>
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#include <error.h>
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#include <pmm.h>
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#include <x86.h>
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#include <swap.h>
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#include <kmalloc.h>
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/*
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vmm design include two parts: mm_struct (mm) & vma_struct (vma)
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mm is the memory manager for the set of continuous virtual memory
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area which have the same PDT. vma is a continuous virtual memory area.
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There a linear link list for vma & a redblack link list for vma in mm.
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---------------
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mm related functions:
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golbal functions
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struct mm_struct * mm_create(void)
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void mm_destroy(struct mm_struct *mm)
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int do_pgfault(struct mm_struct *mm, uint32_t error_code, uintptr_t addr)
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--------------
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vma related functions:
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global functions
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struct vma_struct * vma_create (uintptr_t vm_start, uintptr_t vm_end,...)
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void insert_vma_struct(struct mm_struct *mm, struct vma_struct *vma)
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struct vma_struct * find_vma(struct mm_struct *mm, uintptr_t addr)
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local functions
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inline void check_vma_overlap(struct vma_struct *prev, struct vma_struct *next)
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---------------
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check correctness functions
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void check_vmm(void);
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void check_vma_struct(void);
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void check_pgfault(void);
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*/
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static void check_vmm(void);
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static void check_vma_struct(void);
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static void check_pgfault(void);
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// mm_create - alloc a mm_struct & initialize it.
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struct mm_struct *
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mm_create(void) {
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struct mm_struct *mm = kmalloc(sizeof(struct mm_struct));
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if (mm != NULL) {
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list_init(&(mm->mmap_list));
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mm->mmap_cache = NULL;
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mm->pgdir = NULL;
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mm->map_count = 0;
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if (swap_init_ok) swap_init_mm(mm);
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else mm->sm_priv = NULL;
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set_mm_count(mm, 0);
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sem_init(&(mm->mm_sem), 1);
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}
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return mm;
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}
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// vma_create - alloc a vma_struct & initialize it. (addr range: vm_start~vm_end)
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struct vma_struct *
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vma_create(uintptr_t vm_start, uintptr_t vm_end, uint32_t vm_flags) {
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struct vma_struct *vma = kmalloc(sizeof(struct vma_struct));
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if (vma != NULL) {
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vma->vm_start = vm_start;
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vma->vm_end = vm_end;
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vma->vm_flags = vm_flags;
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}
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return vma;
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}
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// find_vma - find a vma (vma->vm_start <= addr <= vma_vm_end)
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struct vma_struct *
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find_vma(struct mm_struct *mm, uintptr_t addr) {
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struct vma_struct *vma = NULL;
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if (mm != NULL) {
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vma = mm->mmap_cache;
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if (!(vma != NULL && vma->vm_start <= addr && vma->vm_end > addr)) {
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bool found = 0;
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list_entry_t *list = &(mm->mmap_list), *le = list;
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while ((le = list_next(le)) != list) {
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vma = le2vma(le, list_link);
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if (addr < vma->vm_end) {
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found = 1;
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break;
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}
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}
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if (!found) {
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vma = NULL;
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}
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}
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if (vma != NULL) {
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mm->mmap_cache = vma;
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}
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}
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return vma;
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}
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// check_vma_overlap - check if vma1 overlaps vma2 ?
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static inline void
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check_vma_overlap(struct vma_struct *prev, struct vma_struct *next) {
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assert(prev->vm_start < prev->vm_end);
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assert(prev->vm_end <= next->vm_start);
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assert(next->vm_start < next->vm_end);
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}
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// insert_vma_struct -insert vma in mm's list link
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void
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insert_vma_struct(struct mm_struct *mm, struct vma_struct *vma) {
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assert(vma->vm_start < vma->vm_end);
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list_entry_t *list = &(mm->mmap_list);
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list_entry_t *le_prev = list, *le_next;
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list_entry_t *le = list;
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while ((le = list_next(le)) != list) {
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struct vma_struct *mmap_prev = le2vma(le, list_link);
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if (mmap_prev->vm_start > vma->vm_start) {
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break;
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}
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le_prev = le;
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}
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le_next = list_next(le_prev);
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/* check overlap */
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if (le_prev != list) {
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check_vma_overlap(le2vma(le_prev, list_link), vma);
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}
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if (le_next != list) {
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check_vma_overlap(vma, le2vma(le_next, list_link));
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}
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vma->vm_mm = mm;
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list_add_after(le_prev, &(vma->list_link));
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mm->map_count ++;
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}
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// mm_destroy - free mm and mm internal fields
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void
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mm_destroy(struct mm_struct *mm) {
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assert(mm_count(mm) == 0);
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list_entry_t *list = &(mm->mmap_list), *le;
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while ((le = list_next(list)) != list) {
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list_del(le);
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kfree(le2vma(le, list_link)); //kfree vma
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}
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kfree(mm); //kfree mm
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mm=NULL;
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}
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int
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mm_map(struct mm_struct *mm, uintptr_t addr, size_t len, uint32_t vm_flags,
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struct vma_struct **vma_store) {
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uintptr_t start = ROUNDDOWN(addr, PGSIZE), end = ROUNDUP(addr + len, PGSIZE);
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if (!USER_ACCESS(start, end)) {
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return -E_INVAL;
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}
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assert(mm != NULL);
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int ret = -E_INVAL;
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struct vma_struct *vma;
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if ((vma = find_vma(mm, start)) != NULL && end > vma->vm_start) {
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goto out;
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}
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ret = -E_NO_MEM;
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if ((vma = vma_create(start, end, vm_flags)) == NULL) {
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goto out;
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}
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insert_vma_struct(mm, vma);
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if (vma_store != NULL) {
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*vma_store = vma;
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}
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ret = 0;
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out:
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return ret;
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}
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int
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dup_mmap(struct mm_struct *to, struct mm_struct *from) {
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assert(to != NULL && from != NULL);
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list_entry_t *list = &(from->mmap_list), *le = list;
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while ((le = list_prev(le)) != list) {
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struct vma_struct *vma, *nvma;
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vma = le2vma(le, list_link);
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nvma = vma_create(vma->vm_start, vma->vm_end, vma->vm_flags);
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if (nvma == NULL) {
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return -E_NO_MEM;
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}
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insert_vma_struct(to, nvma);
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bool share = 0;
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if (copy_range(to->pgdir, from->pgdir, vma->vm_start, vma->vm_end, share) != 0) {
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return -E_NO_MEM;
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}
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}
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return 0;
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}
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void
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exit_mmap(struct mm_struct *mm) {
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assert(mm != NULL && mm_count(mm) == 0);
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pde_t *pgdir = mm->pgdir;
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list_entry_t *list = &(mm->mmap_list), *le = list;
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while ((le = list_next(le)) != list) {
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struct vma_struct *vma = le2vma(le, list_link);
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unmap_range(pgdir, vma->vm_start, vma->vm_end);
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}
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while ((le = list_next(le)) != list) {
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struct vma_struct *vma = le2vma(le, list_link);
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exit_range(pgdir, vma->vm_start, vma->vm_end);
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}
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}
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bool
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copy_from_user(struct mm_struct *mm, void *dst, const void *src, size_t len, bool writable) {
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if (!user_mem_check(mm, (uintptr_t)src, len, writable)) {
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return 0;
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}
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memcpy(dst, src, len);
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return 1;
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}
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bool
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copy_to_user(struct mm_struct *mm, void *dst, const void *src, size_t len) {
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if (!user_mem_check(mm, (uintptr_t)dst, len, 1)) {
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return 0;
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}
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memcpy(dst, src, len);
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return 1;
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}
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// vmm_init - initialize virtual memory management
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// - now just call check_vmm to check correctness of vmm
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void
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vmm_init(void) {
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check_vmm();
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}
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// check_vmm - check correctness of vmm
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static void
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check_vmm(void) {
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size_t nr_free_pages_store = nr_free_pages();
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check_vma_struct();
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check_pgfault();
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assert(nr_free_pages_store == nr_free_pages());
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cprintf("check_vmm() succeeded.\n");
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}
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static void
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check_vma_struct(void) {
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size_t nr_free_pages_store = nr_free_pages();
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struct mm_struct *mm = mm_create();
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assert(mm != NULL);
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int step1 = 10, step2 = step1 * 10;
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int i;
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for (i = step1; i >= 0; i --) {
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struct vma_struct *vma = vma_create(i * 5, i * 5 + 2, 0);
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assert(vma != NULL);
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insert_vma_struct(mm, vma);
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}
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for (i = step1 + 1; i <= step2; i ++) {
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struct vma_struct *vma = vma_create(i * 5, i * 5 + 2, 0);
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assert(vma != NULL);
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insert_vma_struct(mm, vma);
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}
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list_entry_t *le = list_next(&(mm->mmap_list));
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for (i = 0; i <= step2; i ++) {
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assert(le != &(mm->mmap_list));
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struct vma_struct *mmap = le2vma(le, list_link);
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assert(mmap->vm_start == i * 5 && mmap->vm_end == i * 5 + 2);
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le = list_next(le);
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}
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for (i = 0; i < 5 * step2 + 2; i ++) {
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struct vma_struct *vma = find_vma(mm, i);
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assert(vma != NULL);
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int j = i / 5;
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if (i >= 5 * j + 2) {
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j ++;
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}
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assert(vma->vm_start == j * 5 && vma->vm_end == j * 5 + 2);
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}
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mm_destroy(mm);
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assert(nr_free_pages_store == nr_free_pages());
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cprintf("check_vma_struct() succeeded!\n");
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}
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struct mm_struct *check_mm_struct;
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// check_pgfault - check correctness of pgfault handler
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static void
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check_pgfault(void) {
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size_t nr_free_pages_store = nr_free_pages();
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check_mm_struct = mm_create();
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assert(check_mm_struct != NULL);
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struct mm_struct *mm = check_mm_struct;
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pde_t *pgdir = mm->pgdir = boot_pgdir;
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assert(pgdir[0] == 0);
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struct vma_struct *vma = vma_create(0, PTSIZE, VM_WRITE);
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assert(vma != NULL);
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insert_vma_struct(mm, vma);
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uintptr_t addr = 0x100;
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assert(find_vma(mm, addr) == vma);
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int i, sum = 0;
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for (i = 0; i < 100; i ++) {
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*(char *)(addr + i) = i;
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sum += i;
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}
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for (i = 0; i < 100; i ++) {
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sum -= *(char *)(addr + i);
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}
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assert(sum == 0);
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page_remove(pgdir, ROUNDDOWN(addr, PGSIZE));
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free_page(pa2page(pgdir[0]));
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pgdir[0] = 0;
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mm->pgdir = NULL;
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mm_destroy(mm);
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check_mm_struct = NULL;
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assert(nr_free_pages_store == nr_free_pages());
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cprintf("check_pgfault() succeeded!\n");
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}
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//page fault number
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volatile unsigned int pgfault_num=0;
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/* do_pgfault - interrupt handler to process the page fault execption
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* @mm : the control struct for a set of vma using the same PDT
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* @error_code : the error code recorded in trapframe->tf_err which is setted by x86 hardware
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* @addr : the addr which causes a memory access exception, (the contents of the CR2 register)
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*
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* CALL GRAPH: trap--> trap_dispatch-->pgfault_handler-->do_pgfault
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* The processor provides ucore's do_pgfault function with two items of information to aid in diagnosing
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* the exception and recovering from it.
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* (1) The contents of the CR2 register. The processor loads the CR2 register with the
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* 32-bit linear address that generated the exception. The do_pgfault fun can
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* use this address to locate the corresponding page directory and page-table
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* entries.
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* (2) An error code on the kernel stack. The error code for a page fault has a format different from
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* that for other exceptions. The error code tells the exception handler three things:
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* -- The P flag (bit 0) indicates whether the exception was due to a not-present page (0)
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* or to either an access rights violation or the use of a reserved bit (1).
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* -- The W/R flag (bit 1) indicates whether the memory access that caused the exception
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* was a read (0) or write (1).
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* -- The U/S flag (bit 2) indicates whether the processor was executing at user mode (1)
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* or supervisor mode (0) at the time of the exception.
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*/
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int
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do_pgfault(struct mm_struct *mm, uint32_t error_code, uintptr_t addr) {
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int ret = -E_INVAL;
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//try to find a vma which include addr
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struct vma_struct *vma = find_vma(mm, addr);
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pgfault_num++;
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//If the addr is in the range of a mm's vma?
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if (vma == NULL || vma->vm_start > addr) {
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cprintf("not valid addr %x, and can not find it in vma\n", addr);
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goto failed;
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}
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//check the error_code
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switch (error_code & 3) {
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default:
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/* error code flag : default is 3 ( W/R=1, P=1): write, present */
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case 2: /* error code flag : (W/R=1, P=0): write, not present */
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if (!(vma->vm_flags & VM_WRITE)) {
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cprintf("do_pgfault failed: error code flag = write AND not present, but the addr's vma cannot write\n");
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goto failed;
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}
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break;
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case 1: /* error code flag : (W/R=0, P=1): read, present */
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cprintf("do_pgfault failed: error code flag = read AND present\n");
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goto failed;
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case 0: /* error code flag : (W/R=0, P=0): read, not present */
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if (!(vma->vm_flags & (VM_READ | VM_EXEC))) {
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cprintf("do_pgfault failed: error code flag = read AND not present, but the addr's vma cannot read or exec\n");
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goto failed;
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}
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}
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/* IF (write an existed addr ) OR
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* (write an non_existed addr && addr is writable) OR
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* (read an non_existed addr && addr is readable)
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* THEN
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* continue process
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*/
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uint32_t perm = PTE_U;
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if (vma->vm_flags & VM_WRITE) {
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perm |= PTE_W;
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}
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addr = ROUNDDOWN(addr, PGSIZE);
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ret = -E_NO_MEM;
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pte_t *ptep=NULL;
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/*LAB3 EXERCISE 1: YOUR CODE
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* Maybe you want help comment, BELOW comments can help you finish the code
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*
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* Some Useful MACROs and DEFINEs, you can use them in below implementation.
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* MACROs or Functions:
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* get_pte : get an pte and return the kernel virtual address of this pte for la
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* if the PT contians this pte didn't exist, alloc a page for PT (notice the 3th parameter '1')
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* pgdir_alloc_page : call alloc_page & page_insert functions to allocate a page size memory & setup
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* an addr map pa<--->la with linear address la and the PDT pgdir
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* DEFINES:
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* VM_WRITE : If vma->vm_flags & VM_WRITE == 1/0, then the vma is writable/non writable
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* PTE_W 0x002 // page table/directory entry flags bit : Writeable
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* PTE_U 0x004 // page table/directory entry flags bit : User can access
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* VARIABLES:
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* mm->pgdir : the PDT of these vma
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*
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*/
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#if 0
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/*LAB3 EXERCISE 1: YOUR CODE*/
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ptep = ??? //(1) try to find a pte, if pte's PT(Page Table) isn't existed, then create a PT.
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if (*ptep == 0) {
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//(2) if the phy addr isn't exist, then alloc a page & map the phy addr with logical addr
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}
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else {
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/*LAB3 EXERCISE 2: YOUR CODE
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* Now we think this pte is a swap entry, we should load data from disk to a page with phy addr,
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* and map the phy addr with logical addr, trigger swap manager to record the access situation of this page.
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*
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* Some Useful MACROs and DEFINEs, you can use them in below implementation.
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* MACROs or Functions:
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* swap_in(mm, addr, &page) : alloc a memory page, then according to the swap entry in PTE for addr,
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* find the addr of disk page, read the content of disk page into this memroy page
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* page_insert ： build the map of phy addr of an Page with the linear addr la
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* swap_map_swappable ： set the page swappable
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*/
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/*
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* LAB5 CHALLENGE ( the implmentation Copy on Write)
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There are 2 situlations when code comes here.
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1) *ptep & PTE_P == 1, it means one process try to write a readonly page.
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If the vma includes this addr is writable, then we can set the page writable by rewrite the *ptep.
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This method could be used to implement the Copy on Write (COW) thchnology(a fast fork process method).
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2) *ptep & PTE_P == 0 & but *ptep!=0, it means this pte is a swap entry.
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We should add the LAB3's results here.
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*/
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if(swap_init_ok) {
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struct Page *page=NULL;
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//(1）According to the mm AND addr, try to load the content of right disk page
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// into the memory which page managed.
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//(2) According to the mm, addr AND page, setup the map of phy addr <---> logical addr
|
|
//(3) make the page swappable.
|
|
//(4) [NOTICE]: you myabe need to update your lab3's implementation for LAB5's normal execution.
|
|
}
|
|
else {
|
|
cprintf("no swap_init_ok but ptep is %x, failed\n",*ptep);
|
|
goto failed;
|
|
}
|
|
}
|
|
#endif
|
|
ret = 0;
|
|
failed:
|
|
return ret;
|
|
}
|
|
|
|
bool
|
|
user_mem_check(struct mm_struct *mm, uintptr_t addr, size_t len, bool write) {
|
|
if (mm != NULL) {
|
|
if (!USER_ACCESS(addr, addr + len)) {
|
|
return 0;
|
|
}
|
|
struct vma_struct *vma;
|
|
uintptr_t start = addr, end = addr + len;
|
|
while (start < end) {
|
|
if ((vma = find_vma(mm, start)) == NULL || start < vma->vm_start) {
|
|
return 0;
|
|
}
|
|
if (!(vma->vm_flags & ((write) ? VM_WRITE : VM_READ))) {
|
|
return 0;
|
|
}
|
|
if (write && (vma->vm_flags & VM_STACK)) {
|
|
if (start < vma->vm_start + PGSIZE) { //check stack start & size
|
|
return 0;
|
|
}
|
|
}
|
|
start = vma->vm_end;
|
|
}
|
|
return 1;
|
|
}
|
|
return KERN_ACCESS(addr, addr + len);
|
|
}
|
|
|