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 <asm/uaccess.h>
26 #include <asm/pgtable.h>
27 #include <asm/cacheflush.h>
28 #include <asm/tlbflush.h>
31 static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
37 static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
38 unsigned long addr, unsigned long end, pgprot_t newprot,
39 int dirty_accountable)
44 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
45 arch_enter_lazy_mmu_mode();
48 if (pte_present(oldpte)) {
51 ptent = ptep_modify_prot_start(mm, addr, pte);
52 ptent = pte_modify(ptent, newprot);
55 * Avoid taking write faults for pages we know to be
58 if (dirty_accountable && pte_dirty(ptent))
59 ptent = pte_mkwrite(ptent);
61 ptep_modify_prot_commit(mm, addr, pte, ptent);
62 #ifdef CONFIG_MIGRATION
63 } else if (!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));
78 } while (pte++, addr += PAGE_SIZE, addr != end);
79 arch_leave_lazy_mmu_mode();
80 pte_unmap_unlock(pte - 1, ptl);
83 static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud,
84 unsigned long addr, unsigned long end, pgprot_t newprot,
85 int dirty_accountable)
90 pmd = pmd_offset(pud, addr);
92 next = pmd_addr_end(addr, end);
93 if (pmd_none_or_clear_bad(pmd))
95 change_pte_range(mm, pmd, addr, next, newprot, dirty_accountable);
96 } while (pmd++, addr = next, addr != end);
99 static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd,
100 unsigned long addr, unsigned long end, pgprot_t newprot,
101 int dirty_accountable)
106 pud = pud_offset(pgd, addr);
108 next = pud_addr_end(addr, end);
109 if (pud_none_or_clear_bad(pud))
111 change_pmd_range(mm, pud, addr, next, newprot, dirty_accountable);
112 } while (pud++, addr = next, addr != end);
115 static void change_protection(struct vm_area_struct *vma,
116 unsigned long addr, unsigned long end, pgprot_t newprot,
117 int dirty_accountable)
119 struct mm_struct *mm = vma->vm_mm;
122 unsigned long start = addr;
125 pgd = pgd_offset(mm, addr);
126 flush_cache_range(vma, addr, end);
128 next = pgd_addr_end(addr, end);
129 if (pgd_none_or_clear_bad(pgd))
131 change_pud_range(mm, pgd, addr, next, newprot, dirty_accountable);
132 } while (pgd++, addr = next, addr != end);
133 flush_tlb_range(vma, start, end);
137 mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
138 unsigned long start, unsigned long end, unsigned long newflags)
140 struct mm_struct *mm = vma->vm_mm;
141 unsigned long oldflags = vma->vm_flags;
142 long nrpages = (end - start) >> PAGE_SHIFT;
143 unsigned long charged = 0;
146 int dirty_accountable = 0;
148 if (newflags == oldflags) {
154 * If we make a private mapping writable we increase our commit;
155 * but (without finer accounting) cannot reduce our commit if we
156 * make it unwritable again.
158 if (newflags & VM_WRITE) {
159 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|
160 VM_SHARED|VM_NORESERVE))) {
162 if (security_vm_enough_memory(charged))
164 newflags |= VM_ACCOUNT;
169 * First try to merge with previous and/or next vma.
171 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
172 *pprev = vma_merge(mm, *pprev, start, end, newflags,
173 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
181 if (start != vma->vm_start) {
182 error = split_vma(mm, vma, start, 1);
187 if (end != vma->vm_end) {
188 error = split_vma(mm, vma, end, 0);
195 * vm_flags and vm_page_prot are protected by the mmap_sem
196 * held in write mode.
198 vma->vm_flags = newflags;
199 vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
200 vm_get_page_prot(newflags));
202 if (vma_wants_writenotify(vma)) {
203 vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
204 dirty_accountable = 1;
207 mmu_notifier_invalidate_range_start(mm, start, end);
208 if (is_vm_hugetlb_page(vma))
209 hugetlb_change_protection(vma, start, end, vma->vm_page_prot);
211 change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
212 mmu_notifier_invalidate_range_end(mm, start, end);
213 vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
214 vm_stat_account(mm, newflags, vma->vm_file, nrpages);
218 vm_unacct_memory(charged);
223 sys_mprotect(unsigned long start, size_t len, unsigned long prot)
225 unsigned long vm_flags, nstart, end, tmp, reqprot;
226 struct vm_area_struct *vma, *prev;
228 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
229 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
230 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
233 if (start & ~PAGE_MASK)
237 len = PAGE_ALIGN(len);
241 if (!arch_validate_prot(prot))
246 * Does the application expect PROT_READ to imply PROT_EXEC:
248 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
251 vm_flags = calc_vm_prot_bits(prot);
253 down_write(¤t->mm->mmap_sem);
255 vma = find_vma_prev(current->mm, start, &prev);
259 if (unlikely(grows & PROT_GROWSDOWN)) {
260 if (vma->vm_start >= end)
262 start = vma->vm_start;
264 if (!(vma->vm_flags & VM_GROWSDOWN))
268 if (vma->vm_start > start)
270 if (unlikely(grows & PROT_GROWSUP)) {
273 if (!(vma->vm_flags & VM_GROWSUP))
277 if (start > vma->vm_start)
280 for (nstart = start ; ; ) {
281 unsigned long newflags;
283 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
285 newflags = vm_flags | (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
287 /* newflags >> 4 shift VM_MAY% in place of VM_% */
288 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
293 error = security_file_mprotect(vma, reqprot, prot);
300 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
305 if (nstart < prev->vm_end)
306 nstart = prev->vm_end;
311 if (!vma || vma->vm_start != nstart) {
317 up_write(¤t->mm->mmap_sem);