Merge tag 'nfs-for-3.13-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs
[linux/fpc-iii.git] / mm / mprotect.c
blob26667971c824b08ca3dae7188a965e1e4efe0b79
1 /*
2 * mm/mprotect.c
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
9 */
11 #include <linux/mm.h>
12 #include <linux/hugetlb.h>
13 #include <linux/shm.h>
14 #include <linux/mman.h>
15 #include <linux/fs.h>
16 #include <linux/highmem.h>
17 #include <linux/security.h>
18 #include <linux/mempolicy.h>
19 #include <linux/personality.h>
20 #include <linux/syscalls.h>
21 #include <linux/swap.h>
22 #include <linux/swapops.h>
23 #include <linux/mmu_notifier.h>
24 #include <linux/migrate.h>
25 #include <linux/perf_event.h>
26 #include <asm/uaccess.h>
27 #include <asm/pgtable.h>
28 #include <asm/cacheflush.h>
29 #include <asm/tlbflush.h>
31 #ifndef pgprot_modify
32 static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
34 return newprot;
36 #endif
38 static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
39 unsigned long addr, unsigned long end, pgprot_t newprot,
40 int dirty_accountable, int prot_numa)
42 struct mm_struct *mm = vma->vm_mm;
43 pte_t *pte, oldpte;
44 spinlock_t *ptl;
45 unsigned long pages = 0;
47 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
48 arch_enter_lazy_mmu_mode();
49 do {
50 oldpte = *pte;
51 if (pte_present(oldpte)) {
52 pte_t ptent;
53 bool updated = false;
55 ptent = ptep_modify_prot_start(mm, addr, pte);
56 if (!prot_numa) {
57 ptent = pte_modify(ptent, newprot);
58 updated = true;
59 } else {
60 struct page *page;
62 page = vm_normal_page(vma, addr, oldpte);
63 if (page) {
64 if (!pte_numa(oldpte)) {
65 ptent = pte_mknuma(ptent);
66 updated = true;
72 * Avoid taking write faults for pages we know to be
73 * dirty.
75 if (dirty_accountable && pte_dirty(ptent)) {
76 ptent = pte_mkwrite(ptent);
77 updated = true;
80 if (updated)
81 pages++;
82 ptep_modify_prot_commit(mm, addr, pte, ptent);
83 } else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
84 swp_entry_t entry = pte_to_swp_entry(oldpte);
86 if (is_write_migration_entry(entry)) {
87 pte_t newpte;
89 * A protection check is difficult so
90 * just be safe and disable write
92 make_migration_entry_read(&entry);
93 newpte = swp_entry_to_pte(entry);
94 if (pte_swp_soft_dirty(oldpte))
95 newpte = pte_swp_mksoft_dirty(newpte);
96 set_pte_at(mm, addr, pte, newpte);
98 pages++;
101 } while (pte++, addr += PAGE_SIZE, addr != end);
102 arch_leave_lazy_mmu_mode();
103 pte_unmap_unlock(pte - 1, ptl);
105 return pages;
108 static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
109 pud_t *pud, unsigned long addr, unsigned long end,
110 pgprot_t newprot, int dirty_accountable, int prot_numa)
112 pmd_t *pmd;
113 unsigned long next;
114 unsigned long pages = 0;
115 unsigned long nr_huge_updates = 0;
117 pmd = pmd_offset(pud, addr);
118 do {
119 unsigned long this_pages;
121 next = pmd_addr_end(addr, end);
122 if (pmd_trans_huge(*pmd)) {
123 if (next - addr != HPAGE_PMD_SIZE)
124 split_huge_page_pmd(vma, addr, pmd);
125 else {
126 int nr_ptes = change_huge_pmd(vma, pmd, addr,
127 newprot, prot_numa);
129 if (nr_ptes) {
130 if (nr_ptes == HPAGE_PMD_NR) {
131 pages += HPAGE_PMD_NR;
132 nr_huge_updates++;
134 continue;
137 /* fall through */
139 if (pmd_none_or_clear_bad(pmd))
140 continue;
141 this_pages = change_pte_range(vma, pmd, addr, next, newprot,
142 dirty_accountable, prot_numa);
143 pages += this_pages;
144 } while (pmd++, addr = next, addr != end);
146 if (nr_huge_updates)
147 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
148 return pages;
151 static inline unsigned long change_pud_range(struct vm_area_struct *vma,
152 pgd_t *pgd, unsigned long addr, unsigned long end,
153 pgprot_t newprot, int dirty_accountable, int prot_numa)
155 pud_t *pud;
156 unsigned long next;
157 unsigned long pages = 0;
159 pud = pud_offset(pgd, addr);
160 do {
161 next = pud_addr_end(addr, end);
162 if (pud_none_or_clear_bad(pud))
163 continue;
164 pages += change_pmd_range(vma, pud, addr, next, newprot,
165 dirty_accountable, prot_numa);
166 } while (pud++, addr = next, addr != end);
168 return pages;
171 static unsigned long change_protection_range(struct vm_area_struct *vma,
172 unsigned long addr, unsigned long end, pgprot_t newprot,
173 int dirty_accountable, int prot_numa)
175 struct mm_struct *mm = vma->vm_mm;
176 pgd_t *pgd;
177 unsigned long next;
178 unsigned long start = addr;
179 unsigned long pages = 0;
181 BUG_ON(addr >= end);
182 pgd = pgd_offset(mm, addr);
183 flush_cache_range(vma, addr, end);
184 do {
185 next = pgd_addr_end(addr, end);
186 if (pgd_none_or_clear_bad(pgd))
187 continue;
188 pages += change_pud_range(vma, pgd, addr, next, newprot,
189 dirty_accountable, prot_numa);
190 } while (pgd++, addr = next, addr != end);
192 /* Only flush the TLB if we actually modified any entries: */
193 if (pages)
194 flush_tlb_range(vma, start, end);
196 return pages;
199 unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
200 unsigned long end, pgprot_t newprot,
201 int dirty_accountable, int prot_numa)
203 struct mm_struct *mm = vma->vm_mm;
204 unsigned long pages;
206 mmu_notifier_invalidate_range_start(mm, start, end);
207 if (is_vm_hugetlb_page(vma))
208 pages = hugetlb_change_protection(vma, start, end, newprot);
209 else
210 pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
211 mmu_notifier_invalidate_range_end(mm, start, end);
213 return pages;
217 mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
218 unsigned long start, unsigned long end, unsigned long newflags)
220 struct mm_struct *mm = vma->vm_mm;
221 unsigned long oldflags = vma->vm_flags;
222 long nrpages = (end - start) >> PAGE_SHIFT;
223 unsigned long charged = 0;
224 pgoff_t pgoff;
225 int error;
226 int dirty_accountable = 0;
228 if (newflags == oldflags) {
229 *pprev = vma;
230 return 0;
234 * If we make a private mapping writable we increase our commit;
235 * but (without finer accounting) cannot reduce our commit if we
236 * make it unwritable again. hugetlb mapping were accounted for
237 * even if read-only so there is no need to account for them here
239 if (newflags & VM_WRITE) {
240 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
241 VM_SHARED|VM_NORESERVE))) {
242 charged = nrpages;
243 if (security_vm_enough_memory_mm(mm, charged))
244 return -ENOMEM;
245 newflags |= VM_ACCOUNT;
250 * First try to merge with previous and/or next vma.
252 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
253 *pprev = vma_merge(mm, *pprev, start, end, newflags,
254 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
255 if (*pprev) {
256 vma = *pprev;
257 goto success;
260 *pprev = vma;
262 if (start != vma->vm_start) {
263 error = split_vma(mm, vma, start, 1);
264 if (error)
265 goto fail;
268 if (end != vma->vm_end) {
269 error = split_vma(mm, vma, end, 0);
270 if (error)
271 goto fail;
274 success:
276 * vm_flags and vm_page_prot are protected by the mmap_sem
277 * held in write mode.
279 vma->vm_flags = newflags;
280 vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
281 vm_get_page_prot(newflags));
283 if (vma_wants_writenotify(vma)) {
284 vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
285 dirty_accountable = 1;
288 change_protection(vma, start, end, vma->vm_page_prot,
289 dirty_accountable, 0);
291 vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
292 vm_stat_account(mm, newflags, vma->vm_file, nrpages);
293 perf_event_mmap(vma);
294 return 0;
296 fail:
297 vm_unacct_memory(charged);
298 return error;
301 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
302 unsigned long, prot)
304 unsigned long vm_flags, nstart, end, tmp, reqprot;
305 struct vm_area_struct *vma, *prev;
306 int error = -EINVAL;
307 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
308 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
309 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
310 return -EINVAL;
312 if (start & ~PAGE_MASK)
313 return -EINVAL;
314 if (!len)
315 return 0;
316 len = PAGE_ALIGN(len);
317 end = start + len;
318 if (end <= start)
319 return -ENOMEM;
320 if (!arch_validate_prot(prot))
321 return -EINVAL;
323 reqprot = prot;
325 * Does the application expect PROT_READ to imply PROT_EXEC:
327 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
328 prot |= PROT_EXEC;
330 vm_flags = calc_vm_prot_bits(prot);
332 down_write(&current->mm->mmap_sem);
334 vma = find_vma(current->mm, start);
335 error = -ENOMEM;
336 if (!vma)
337 goto out;
338 prev = vma->vm_prev;
339 if (unlikely(grows & PROT_GROWSDOWN)) {
340 if (vma->vm_start >= end)
341 goto out;
342 start = vma->vm_start;
343 error = -EINVAL;
344 if (!(vma->vm_flags & VM_GROWSDOWN))
345 goto out;
346 } else {
347 if (vma->vm_start > start)
348 goto out;
349 if (unlikely(grows & PROT_GROWSUP)) {
350 end = vma->vm_end;
351 error = -EINVAL;
352 if (!(vma->vm_flags & VM_GROWSUP))
353 goto out;
356 if (start > vma->vm_start)
357 prev = vma;
359 for (nstart = start ; ; ) {
360 unsigned long newflags;
362 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
364 newflags = vm_flags;
365 newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
367 /* newflags >> 4 shift VM_MAY% in place of VM_% */
368 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
369 error = -EACCES;
370 goto out;
373 error = security_file_mprotect(vma, reqprot, prot);
374 if (error)
375 goto out;
377 tmp = vma->vm_end;
378 if (tmp > end)
379 tmp = end;
380 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
381 if (error)
382 goto out;
383 nstart = tmp;
385 if (nstart < prev->vm_end)
386 nstart = prev->vm_end;
387 if (nstart >= end)
388 goto out;
390 vma = prev->vm_next;
391 if (!vma || vma->vm_start != nstart) {
392 error = -ENOMEM;
393 goto out;
396 out:
397 up_write(&current->mm->mmap_sem);
398 return error;