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/shm.h>
14 #include <linux/mman.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 static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
32 unsigned long addr, unsigned long end, pgprot_t newprot,
33 int dirty_accountable)
38 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
39 arch_enter_lazy_mmu_mode();
42 if (pte_present(oldpte)) {
45 ptent = ptep_modify_prot_start(mm, addr, pte);
46 ptent = pte_modify(ptent, newprot);
49 * Avoid taking write faults for pages we know to be
52 if (dirty_accountable && pte_dirty(ptent))
53 ptent = pte_mkwrite(ptent);
55 ptep_modify_prot_commit(mm, addr, pte, ptent);
56 } else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
57 swp_entry_t entry = pte_to_swp_entry(oldpte);
59 if (is_write_migration_entry(entry)) {
61 * A protection check is difficult so
62 * just be safe and disable write
64 make_migration_entry_read(&entry);
65 set_pte_at(mm, addr, pte,
66 swp_entry_to_pte(entry));
69 } while (pte++, addr += PAGE_SIZE, addr != end);
70 arch_leave_lazy_mmu_mode();
71 pte_unmap_unlock(pte - 1, ptl);
74 static inline void change_pmd_range(struct vm_area_struct *vma, pud_t *pud,
75 unsigned long addr, unsigned long end, pgprot_t newprot,
76 int dirty_accountable)
81 pmd = pmd_offset(pud, addr);
83 next = pmd_addr_end(addr, end);
84 if (pmd_trans_huge(*pmd)) {
85 if (next - addr != HPAGE_PMD_SIZE)
86 split_huge_page_pmd(vma->vm_mm, pmd);
87 else if (change_huge_pmd(vma, pmd, addr, newprot))
91 if (pmd_none_or_clear_bad(pmd))
93 change_pte_range(vma->vm_mm, pmd, addr, next, newprot,
95 } while (pmd++, addr = next, addr != end);
98 static inline void change_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
99 unsigned long addr, unsigned long end, pgprot_t newprot,
100 int dirty_accountable)
105 pud = pud_offset(pgd, addr);
107 next = pud_addr_end(addr, end);
108 if (pud_none_or_clear_bad(pud))
110 change_pmd_range(vma, pud, addr, next, newprot,
112 } while (pud++, addr = next, addr != end);
115 static void change_protection_range(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(vma, pgd, addr, next, newprot,
133 } while (pgd++, addr = next, addr != end);
134 flush_tlb_range(vma, start, end);
137 void change_protection(struct vm_area_struct *vma, unsigned long start,
138 unsigned long end, pgprot_t newprot,
139 int dirty_accountable)
141 struct mm_struct *mm = vma->vm_mm;
143 mmu_notifier_invalidate_range_start(mm, start, end);
144 if (is_vm_hugetlb_page(vma))
145 hugetlb_change_protection(vma, start, end, newprot);
147 change_protection_range(vma, start, end, newprot, dirty_accountable);
148 mmu_notifier_invalidate_range_end(mm, start, end);
152 mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
153 unsigned long start, unsigned long end, unsigned long newflags)
155 struct mm_struct *mm = vma->vm_mm;
156 unsigned long oldflags = vma->vm_flags;
157 long nrpages = (end - start) >> PAGE_SHIFT;
158 unsigned long charged = 0;
161 int dirty_accountable = 0;
163 if (newflags == oldflags) {
169 * If we make a private mapping writable we increase our commit;
170 * but (without finer accounting) cannot reduce our commit if we
171 * make it unwritable again. hugetlb mapping were accounted for
172 * even if read-only so there is no need to account for them here
174 if (newflags & VM_WRITE) {
175 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
176 VM_SHARED|VM_NORESERVE))) {
178 if (security_vm_enough_memory_mm(mm, charged))
180 newflags |= VM_ACCOUNT;
185 * First try to merge with previous and/or next vma.
187 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
188 *pprev = vma_merge(mm, *pprev, start, end, newflags,
189 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
197 if (start != vma->vm_start) {
198 error = split_vma(mm, vma, start, 1);
203 if (end != vma->vm_end) {
204 error = split_vma(mm, vma, end, 0);
211 * vm_flags and vm_page_prot are protected by the mmap_sem
212 * held in write mode.
214 vma->vm_flags = newflags;
215 vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
216 vm_get_page_prot(newflags));
218 if (vma_wants_writenotify(vma)) {
219 vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
220 dirty_accountable = 1;
223 change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
225 vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
226 vm_stat_account(mm, newflags, vma->vm_file, nrpages);
227 perf_event_mmap(vma);
231 vm_unacct_memory(charged);
235 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
238 unsigned long vm_flags, nstart, end, tmp, reqprot;
239 struct vm_area_struct *vma, *prev;
241 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
242 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
243 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
246 if (start & ~PAGE_MASK)
250 len = PAGE_ALIGN(len);
254 if (!arch_validate_prot(prot))
259 * Does the application expect PROT_READ to imply PROT_EXEC:
261 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
264 vm_flags = calc_vm_prot_bits(prot);
266 down_write(¤t->mm->mmap_sem);
268 vma = find_vma(current->mm, start);
273 if (unlikely(grows & PROT_GROWSDOWN)) {
274 if (vma->vm_start >= end)
276 start = vma->vm_start;
278 if (!(vma->vm_flags & VM_GROWSDOWN))
282 if (vma->vm_start > start)
284 if (unlikely(grows & PROT_GROWSUP)) {
287 if (!(vma->vm_flags & VM_GROWSUP))
291 if (start > vma->vm_start)
294 for (nstart = start ; ; ) {
295 unsigned long newflags;
297 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
299 newflags = vm_flags | (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
301 /* newflags >> 4 shift VM_MAY% in place of VM_% */
302 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
307 error = security_file_mprotect(vma, reqprot, prot);
314 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
319 if (nstart < prev->vm_end)
320 nstart = prev->vm_end;
325 if (!vma || vma->vm_start != nstart) {
331 up_write(¤t->mm->mmap_sem);