4 * (C) Copyright 1994 Linus Torvalds
5 * (C) Copyright 2002 Christoph Hellwig
7 * Address space accounting code <alan@redhat.com>
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 <asm/uaccess.h>
25 #include <asm/pgtable.h>
26 #include <asm/cacheflush.h>
27 #include <asm/tlbflush.h>
29 static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
30 unsigned long addr, unsigned long end, pgprot_t newprot)
35 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
38 if (pte_present(oldpte)) {
41 /* Avoid an SMP race with hardware updated dirty/clean
42 * bits by wiping the pte and then setting the new pte
45 ptent = pte_modify(ptep_get_and_clear(mm, addr, pte), newprot);
46 set_pte_at(mm, addr, pte, ptent);
47 lazy_mmu_prot_update(ptent);
48 #ifdef CONFIG_MIGRATION
49 } else if (!pte_file(oldpte)) {
50 swp_entry_t entry = pte_to_swp_entry(oldpte);
52 if (is_write_migration_entry(entry)) {
54 * A protection check is difficult so
55 * just be safe and disable write
57 make_migration_entry_read(&entry);
58 set_pte_at(mm, addr, pte,
59 swp_entry_to_pte(entry));
64 } while (pte++, addr += PAGE_SIZE, addr != end);
65 pte_unmap_unlock(pte - 1, ptl);
68 static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud,
69 unsigned long addr, unsigned long end, pgprot_t newprot)
74 pmd = pmd_offset(pud, addr);
76 next = pmd_addr_end(addr, end);
77 if (pmd_none_or_clear_bad(pmd))
79 change_pte_range(mm, pmd, addr, next, newprot);
80 } while (pmd++, addr = next, addr != end);
83 static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd,
84 unsigned long addr, unsigned long end, pgprot_t newprot)
89 pud = pud_offset(pgd, addr);
91 next = pud_addr_end(addr, end);
92 if (pud_none_or_clear_bad(pud))
94 change_pmd_range(mm, pud, addr, next, newprot);
95 } while (pud++, addr = next, addr != end);
98 static void change_protection(struct vm_area_struct *vma,
99 unsigned long addr, unsigned long end, pgprot_t newprot)
101 struct mm_struct *mm = vma->vm_mm;
104 unsigned long start = addr;
107 pgd = pgd_offset(mm, addr);
108 flush_cache_range(vma, addr, end);
110 next = pgd_addr_end(addr, end);
111 if (pgd_none_or_clear_bad(pgd))
113 change_pud_range(mm, pgd, addr, next, newprot);
114 } while (pgd++, addr = next, addr != end);
115 flush_tlb_range(vma, start, end);
119 mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
120 unsigned long start, unsigned long end, unsigned long newflags)
122 struct mm_struct *mm = vma->vm_mm;
123 unsigned long oldflags = vma->vm_flags;
124 long nrpages = (end - start) >> PAGE_SHIFT;
125 unsigned long charged = 0;
129 if (newflags == oldflags) {
135 * If we make a private mapping writable we increase our commit;
136 * but (without finer accounting) cannot reduce our commit if we
137 * make it unwritable again.
139 * FIXME? We haven't defined a VM_NORESERVE flag, so mprotecting
140 * a MAP_NORESERVE private mapping to writable will now reserve.
142 if (newflags & VM_WRITE) {
143 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_SHARED))) {
145 if (security_vm_enough_memory(charged))
147 newflags |= VM_ACCOUNT;
152 * First try to merge with previous and/or next vma.
154 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
155 *pprev = vma_merge(mm, *pprev, start, end, newflags,
156 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
164 if (start != vma->vm_start) {
165 error = split_vma(mm, vma, start, 1);
170 if (end != vma->vm_end) {
171 error = split_vma(mm, vma, end, 0);
178 * vm_flags and vm_page_prot are protected by the mmap_sem
179 * held in write mode.
181 vma->vm_flags = newflags;
182 vma->vm_page_prot = protection_map[newflags &
183 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)];
184 if (vma_wants_writenotify(vma))
185 vma->vm_page_prot = protection_map[newflags &
186 (VM_READ|VM_WRITE|VM_EXEC)];
188 if (is_vm_hugetlb_page(vma))
189 hugetlb_change_protection(vma, start, end, vma->vm_page_prot);
191 change_protection(vma, start, end, vma->vm_page_prot);
192 vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
193 vm_stat_account(mm, newflags, vma->vm_file, nrpages);
197 vm_unacct_memory(charged);
202 sys_mprotect(unsigned long start, size_t len, unsigned long prot)
204 unsigned long vm_flags, nstart, end, tmp, reqprot;
205 struct vm_area_struct *vma, *prev;
207 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
208 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
209 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
212 if (start & ~PAGE_MASK)
216 len = PAGE_ALIGN(len);
220 if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM))
225 * Does the application expect PROT_READ to imply PROT_EXEC:
227 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
230 vm_flags = calc_vm_prot_bits(prot);
232 down_write(¤t->mm->mmap_sem);
234 vma = find_vma_prev(current->mm, start, &prev);
238 if (unlikely(grows & PROT_GROWSDOWN)) {
239 if (vma->vm_start >= end)
241 start = vma->vm_start;
243 if (!(vma->vm_flags & VM_GROWSDOWN))
247 if (vma->vm_start > start)
249 if (unlikely(grows & PROT_GROWSUP)) {
252 if (!(vma->vm_flags & VM_GROWSUP))
256 if (start > vma->vm_start)
259 for (nstart = start ; ; ) {
260 unsigned long newflags;
262 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
264 newflags = vm_flags | (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
266 /* newflags >> 4 shift VM_MAY% in place of VM_% */
267 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
272 error = security_file_mprotect(vma, reqprot, prot);
279 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
284 if (nstart < prev->vm_end)
285 nstart = prev->vm_end;
290 if (!vma || vma->vm_start != nstart) {
296 up_write(¤t->mm->mmap_sem);