4 * (C) Copyright 1994 Linus Torvalds
5 * (C) Copyright 2002 Christoph Hellwig
7 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
8 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
12 #include <linux/hugetlb.h>
13 #include <linux/slab.h>
14 #include <linux/shm.h>
15 #include <linux/mman.h>
17 #include <linux/highmem.h>
18 #include <linux/security.h>
19 #include <linux/mempolicy.h>
20 #include <linux/personality.h>
21 #include <linux/syscalls.h>
22 #include <linux/swap.h>
23 #include <linux/swapops.h>
24 #include <linux/mmu_notifier.h>
25 #include <linux/migrate.h>
26 #include <asm/uaccess.h>
27 #include <asm/pgtable.h>
28 #include <asm/cacheflush.h>
29 #include <asm/tlbflush.h>
32 static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
38 static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
39 unsigned long addr, unsigned long end, pgprot_t newprot,
40 int dirty_accountable)
45 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
46 arch_enter_lazy_mmu_mode();
49 if (pte_present(oldpte)) {
52 ptent = ptep_modify_prot_start(mm, addr, pte);
53 ptent = pte_modify(ptent, newprot);
56 * Avoid taking write faults for pages we know to be
59 if (dirty_accountable && pte_dirty(ptent))
60 ptent = pte_mkwrite(ptent);
62 ptep_modify_prot_commit(mm, addr, pte, ptent);
63 } else if (PAGE_MIGRATION && !pte_file(oldpte)) {
64 swp_entry_t entry = pte_to_swp_entry(oldpte);
66 if (is_write_migration_entry(entry)) {
68 * A protection check is difficult so
69 * just be safe and disable write
71 make_migration_entry_read(&entry);
72 set_pte_at(mm, addr, pte,
73 swp_entry_to_pte(entry));
76 } while (pte++, addr += PAGE_SIZE, addr != end);
77 arch_leave_lazy_mmu_mode();
78 pte_unmap_unlock(pte - 1, ptl);
81 static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud,
82 unsigned long addr, unsigned long end, pgprot_t newprot,
83 int dirty_accountable)
88 pmd = pmd_offset(pud, addr);
90 next = pmd_addr_end(addr, end);
91 if (pmd_none_or_clear_bad(pmd))
93 change_pte_range(mm, pmd, addr, next, newprot, dirty_accountable);
94 } while (pmd++, addr = next, addr != end);
97 static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd,
98 unsigned long addr, unsigned long end, pgprot_t newprot,
99 int dirty_accountable)
104 pud = pud_offset(pgd, addr);
106 next = pud_addr_end(addr, end);
107 if (pud_none_or_clear_bad(pud))
109 change_pmd_range(mm, pud, addr, next, newprot, dirty_accountable);
110 } while (pud++, addr = next, addr != end);
113 static void change_protection(struct vm_area_struct *vma,
114 unsigned long addr, unsigned long end, pgprot_t newprot,
115 int dirty_accountable)
117 struct mm_struct *mm = vma->vm_mm;
120 unsigned long start = addr;
123 pgd = pgd_offset(mm, addr);
124 flush_cache_range(vma, addr, end);
126 next = pgd_addr_end(addr, end);
127 if (pgd_none_or_clear_bad(pgd))
129 change_pud_range(mm, pgd, addr, next, newprot, dirty_accountable);
130 } while (pgd++, addr = next, addr != end);
131 flush_tlb_range(vma, start, end);
135 mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
136 unsigned long start, unsigned long end, unsigned long newflags)
138 struct mm_struct *mm = vma->vm_mm;
139 unsigned long oldflags = vma->vm_flags;
140 long nrpages = (end - start) >> PAGE_SHIFT;
141 unsigned long charged = 0;
144 int dirty_accountable = 0;
146 if (newflags == oldflags) {
152 * If we make a private mapping writable we increase our commit;
153 * but (without finer accounting) cannot reduce our commit if we
154 * make it unwritable again.
156 if (newflags & VM_WRITE) {
157 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|
158 VM_SHARED|VM_NORESERVE))) {
160 if (security_vm_enough_memory(charged))
162 newflags |= VM_ACCOUNT;
167 * First try to merge with previous and/or next vma.
169 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
170 *pprev = vma_merge(mm, *pprev, start, end, newflags,
171 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
179 if (start != vma->vm_start) {
180 error = split_vma(mm, vma, start, 1);
185 if (end != vma->vm_end) {
186 error = split_vma(mm, vma, end, 0);
193 * vm_flags and vm_page_prot are protected by the mmap_sem
194 * held in write mode.
196 vma->vm_flags = newflags;
197 vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
198 vm_get_page_prot(newflags));
200 if (vma_wants_writenotify(vma)) {
201 vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
202 dirty_accountable = 1;
205 mmu_notifier_invalidate_range_start(mm, start, end);
206 if (is_vm_hugetlb_page(vma))
207 hugetlb_change_protection(vma, start, end, vma->vm_page_prot);
209 change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
210 mmu_notifier_invalidate_range_end(mm, start, end);
211 vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
212 vm_stat_account(mm, newflags, vma->vm_file, nrpages);
216 vm_unacct_memory(charged);
220 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
223 unsigned long vm_flags, nstart, end, tmp, reqprot;
224 struct vm_area_struct *vma, *prev;
226 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
227 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
228 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
231 if (start & ~PAGE_MASK)
235 len = PAGE_ALIGN(len);
239 if (!arch_validate_prot(prot))
244 * Does the application expect PROT_READ to imply PROT_EXEC:
246 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
249 vm_flags = calc_vm_prot_bits(prot);
251 down_write(¤t->mm->mmap_sem);
253 vma = find_vma_prev(current->mm, start, &prev);
257 if (unlikely(grows & PROT_GROWSDOWN)) {
258 if (vma->vm_start >= end)
260 start = vma->vm_start;
262 if (!(vma->vm_flags & VM_GROWSDOWN))
266 if (vma->vm_start > start)
268 if (unlikely(grows & PROT_GROWSUP)) {
271 if (!(vma->vm_flags & VM_GROWSUP))
275 if (start > vma->vm_start)
278 for (nstart = start ; ; ) {
279 unsigned long newflags;
281 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
283 newflags = vm_flags | (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
285 /* newflags >> 4 shift VM_MAY% in place of VM_% */
286 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
291 error = security_file_mprotect(vma, reqprot, prot);
298 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
303 if (nstart < prev->vm_end)
304 nstart = prev->vm_end;
309 if (!vma || vma->vm_start != nstart) {
315 up_write(¤t->mm->mmap_sem);