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 <linux/ksm.h>
27 #include <asm/uaccess.h>
28 #include <asm/pgtable.h>
29 #include <asm/cacheflush.h>
30 #include <asm/tlbflush.h>
33 * For a prot_numa update we only hold mmap_sem for read so there is a
34 * potential race with faulting where a pmd was temporarily none. This
35 * function checks for a transhuge pmd under the appropriate lock. It
36 * returns a pte if it was successfully locked or NULL if it raced with
37 * a transhuge insertion.
39 static pte_t
*lock_pte_protection(struct vm_area_struct
*vma
, pmd_t
*pmd
,
40 unsigned long addr
, int prot_numa
, spinlock_t
**ptl
)
45 /* !prot_numa is protected by mmap_sem held for write */
47 return pte_offset_map_lock(vma
->vm_mm
, pmd
, addr
, ptl
);
49 pmdl
= pmd_lock(vma
->vm_mm
, pmd
);
50 if (unlikely(pmd_trans_huge(*pmd
) || pmd_none(*pmd
))) {
55 pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, addr
, ptl
);
60 static unsigned long change_pte_range(struct vm_area_struct
*vma
, pmd_t
*pmd
,
61 unsigned long addr
, unsigned long end
, pgprot_t newprot
,
62 int dirty_accountable
, int prot_numa
)
64 struct mm_struct
*mm
= vma
->vm_mm
;
67 unsigned long pages
= 0;
69 pte
= lock_pte_protection(vma
, pmd
, addr
, prot_numa
, &ptl
);
73 arch_enter_lazy_mmu_mode();
76 if (pte_present(oldpte
)) {
79 ptent
= ptep_modify_prot_start(mm
, addr
, pte
);
80 ptent
= pte_modify(ptent
, newprot
);
82 /* Avoid taking write faults for known dirty pages */
83 if (dirty_accountable
&& pte_dirty(ptent
) &&
84 (pte_soft_dirty(ptent
) ||
85 !(vma
->vm_flags
& VM_SOFTDIRTY
))) {
86 ptent
= pte_mkwrite(ptent
);
88 ptep_modify_prot_commit(mm
, addr
, pte
, ptent
);
90 } else if (IS_ENABLED(CONFIG_MIGRATION
)) {
91 swp_entry_t entry
= pte_to_swp_entry(oldpte
);
93 if (is_write_migration_entry(entry
)) {
96 * A protection check is difficult so
97 * just be safe and disable write
99 make_migration_entry_read(&entry
);
100 newpte
= swp_entry_to_pte(entry
);
101 if (pte_swp_soft_dirty(oldpte
))
102 newpte
= pte_swp_mksoft_dirty(newpte
);
103 set_pte_at(mm
, addr
, pte
, newpte
);
108 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
109 arch_leave_lazy_mmu_mode();
110 pte_unmap_unlock(pte
- 1, ptl
);
115 static inline unsigned long change_pmd_range(struct vm_area_struct
*vma
,
116 pud_t
*pud
, unsigned long addr
, unsigned long end
,
117 pgprot_t newprot
, int dirty_accountable
, int prot_numa
)
120 struct mm_struct
*mm
= vma
->vm_mm
;
122 unsigned long pages
= 0;
123 unsigned long nr_huge_updates
= 0;
124 unsigned long mni_start
= 0;
126 pmd
= pmd_offset(pud
, addr
);
128 unsigned long this_pages
;
130 next
= pmd_addr_end(addr
, end
);
131 if (!pmd_trans_huge(*pmd
) && pmd_none_or_clear_bad(pmd
))
134 /* invoke the mmu notifier if the pmd is populated */
137 mmu_notifier_invalidate_range_start(mm
, mni_start
, end
);
140 if (pmd_trans_huge(*pmd
)) {
141 if (next
- addr
!= HPAGE_PMD_SIZE
)
142 split_huge_page_pmd(vma
, addr
, pmd
);
144 int nr_ptes
= change_huge_pmd(vma
, pmd
, addr
,
148 if (nr_ptes
== HPAGE_PMD_NR
) {
149 pages
+= HPAGE_PMD_NR
;
153 /* huge pmd was handled */
157 /* fall through, the trans huge pmd just split */
159 this_pages
= change_pte_range(vma
, pmd
, addr
, next
, newprot
,
160 dirty_accountable
, prot_numa
);
162 } while (pmd
++, addr
= next
, addr
!= end
);
165 mmu_notifier_invalidate_range_end(mm
, mni_start
, end
);
168 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES
, nr_huge_updates
);
172 static inline unsigned long change_pud_range(struct vm_area_struct
*vma
,
173 pgd_t
*pgd
, unsigned long addr
, unsigned long end
,
174 pgprot_t newprot
, int dirty_accountable
, int prot_numa
)
178 unsigned long pages
= 0;
180 pud
= pud_offset(pgd
, addr
);
182 next
= pud_addr_end(addr
, end
);
183 if (pud_none_or_clear_bad(pud
))
185 pages
+= change_pmd_range(vma
, pud
, addr
, next
, newprot
,
186 dirty_accountable
, prot_numa
);
187 } while (pud
++, addr
= next
, addr
!= end
);
192 static unsigned long change_protection_range(struct vm_area_struct
*vma
,
193 unsigned long addr
, unsigned long end
, pgprot_t newprot
,
194 int dirty_accountable
, int prot_numa
)
196 struct mm_struct
*mm
= vma
->vm_mm
;
199 unsigned long start
= addr
;
200 unsigned long pages
= 0;
203 pgd
= pgd_offset(mm
, addr
);
204 flush_cache_range(vma
, addr
, end
);
205 set_tlb_flush_pending(mm
);
207 next
= pgd_addr_end(addr
, end
);
208 if (pgd_none_or_clear_bad(pgd
))
210 pages
+= change_pud_range(vma
, pgd
, addr
, next
, newprot
,
211 dirty_accountable
, prot_numa
);
212 } while (pgd
++, addr
= next
, addr
!= end
);
214 /* Only flush the TLB if we actually modified any entries: */
216 flush_tlb_range(vma
, start
, end
);
217 clear_tlb_flush_pending(mm
);
222 unsigned long change_protection(struct vm_area_struct
*vma
, unsigned long start
,
223 unsigned long end
, pgprot_t newprot
,
224 int dirty_accountable
, int prot_numa
)
228 if (is_vm_hugetlb_page(vma
))
229 pages
= hugetlb_change_protection(vma
, start
, end
, newprot
);
231 pages
= change_protection_range(vma
, start
, end
, newprot
, dirty_accountable
, prot_numa
);
237 mprotect_fixup(struct vm_area_struct
*vma
, struct vm_area_struct
**pprev
,
238 unsigned long start
, unsigned long end
, unsigned long newflags
)
240 struct mm_struct
*mm
= vma
->vm_mm
;
241 unsigned long oldflags
= vma
->vm_flags
;
242 long nrpages
= (end
- start
) >> PAGE_SHIFT
;
243 unsigned long charged
= 0;
246 int dirty_accountable
= 0;
248 if (newflags
== oldflags
) {
254 * If we make a private mapping writable we increase our commit;
255 * but (without finer accounting) cannot reduce our commit if we
256 * make it unwritable again. hugetlb mapping were accounted for
257 * even if read-only so there is no need to account for them here
259 if (newflags
& VM_WRITE
) {
260 if (!(oldflags
& (VM_ACCOUNT
|VM_WRITE
|VM_HUGETLB
|
261 VM_SHARED
|VM_NORESERVE
))) {
263 if (security_vm_enough_memory_mm(mm
, charged
))
265 newflags
|= VM_ACCOUNT
;
270 * First try to merge with previous and/or next vma.
272 pgoff
= vma
->vm_pgoff
+ ((start
- vma
->vm_start
) >> PAGE_SHIFT
);
273 *pprev
= vma_merge(mm
, *pprev
, start
, end
, newflags
,
274 vma
->anon_vma
, vma
->vm_file
, pgoff
, vma_policy(vma
));
282 if (start
!= vma
->vm_start
) {
283 error
= split_vma(mm
, vma
, start
, 1);
288 if (end
!= vma
->vm_end
) {
289 error
= split_vma(mm
, vma
, end
, 0);
296 * vm_flags and vm_page_prot are protected by the mmap_sem
297 * held in write mode.
299 vma
->vm_flags
= newflags
;
300 dirty_accountable
= vma_wants_writenotify(vma
);
301 vma_set_page_prot(vma
);
303 change_protection(vma
, start
, end
, vma
->vm_page_prot
,
304 dirty_accountable
, 0);
306 vm_stat_account(mm
, oldflags
, vma
->vm_file
, -nrpages
);
307 vm_stat_account(mm
, newflags
, vma
->vm_file
, nrpages
);
308 perf_event_mmap(vma
);
312 vm_unacct_memory(charged
);
316 SYSCALL_DEFINE3(mprotect
, unsigned long, start
, size_t, len
,
319 unsigned long vm_flags
, nstart
, end
, tmp
, reqprot
;
320 struct vm_area_struct
*vma
, *prev
;
322 const int grows
= prot
& (PROT_GROWSDOWN
|PROT_GROWSUP
);
323 prot
&= ~(PROT_GROWSDOWN
|PROT_GROWSUP
);
324 if (grows
== (PROT_GROWSDOWN
|PROT_GROWSUP
)) /* can't be both */
327 if (start
& ~PAGE_MASK
)
331 len
= PAGE_ALIGN(len
);
335 if (!arch_validate_prot(prot
))
340 * Does the application expect PROT_READ to imply PROT_EXEC:
342 if ((prot
& PROT_READ
) && (current
->personality
& READ_IMPLIES_EXEC
))
345 vm_flags
= calc_vm_prot_bits(prot
);
347 down_write(¤t
->mm
->mmap_sem
);
349 vma
= find_vma(current
->mm
, start
);
354 if (unlikely(grows
& PROT_GROWSDOWN
)) {
355 if (vma
->vm_start
>= end
)
357 start
= vma
->vm_start
;
359 if (!(vma
->vm_flags
& VM_GROWSDOWN
))
362 if (vma
->vm_start
> start
)
364 if (unlikely(grows
& PROT_GROWSUP
)) {
367 if (!(vma
->vm_flags
& VM_GROWSUP
))
371 if (start
> vma
->vm_start
)
374 for (nstart
= start
; ; ) {
375 unsigned long newflags
;
377 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
380 newflags
|= (vma
->vm_flags
& ~(VM_READ
| VM_WRITE
| VM_EXEC
));
382 /* newflags >> 4 shift VM_MAY% in place of VM_% */
383 if ((newflags
& ~(newflags
>> 4)) & (VM_READ
| VM_WRITE
| VM_EXEC
)) {
388 error
= security_file_mprotect(vma
, reqprot
, prot
);
395 error
= mprotect_fixup(vma
, &prev
, nstart
, tmp
, newflags
);
400 if (nstart
< prev
->vm_end
)
401 nstart
= prev
->vm_end
;
406 if (!vma
|| vma
->vm_start
!= nstart
) {
412 up_write(¤t
->mm
->mmap_sem
);
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