Merge remote-tracking branch 'grant/devicetree/merge' into dt-fixes
[firefly-linux-kernel-4.4.55.git] / mm / mprotect.c
1 /*
2  *  mm/mprotect.c
3  *
4  *  (C) Copyright 1994 Linus Torvalds
5  *  (C) Copyright 2002 Christoph Hellwig
6  *
7  *  Address space accounting code       <alan@lxorguk.ukuu.org.uk>
8  *  (C) Copyright 2002 Red Hat Inc, All Rights Reserved
9  */
10
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>
30
31 #ifndef pgprot_modify
32 static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
33 {
34         return newprot;
35 }
36 #endif
37
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)
41 {
42         struct mm_struct *mm = vma->vm_mm;
43         pte_t *pte, oldpte;
44         spinlock_t *ptl;
45         unsigned long pages = 0;
46
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;
54
55                         if (!prot_numa) {
56                                 ptent = ptep_modify_prot_start(mm, addr, pte);
57                                 if (pte_numa(ptent))
58                                         ptent = pte_mknonnuma(ptent);
59                                 ptent = pte_modify(ptent, newprot);
60                                 updated = true;
61                         } else {
62                                 struct page *page;
63
64                                 ptent = *pte;
65                                 page = vm_normal_page(vma, addr, oldpte);
66                                 if (page) {
67                                         if (!pte_numa(oldpte)) {
68                                                 ptent = pte_mknuma(ptent);
69                                                 set_pte_at(mm, addr, pte, ptent);
70                                                 updated = true;
71                                         }
72                                 }
73                         }
74
75                         /*
76                          * Avoid taking write faults for pages we know to be
77                          * dirty.
78                          */
79                         if (dirty_accountable && pte_dirty(ptent)) {
80                                 ptent = pte_mkwrite(ptent);
81                                 updated = true;
82                         }
83
84                         if (updated)
85                                 pages++;
86
87                         /* Only !prot_numa always clears the pte */
88                         if (!prot_numa)
89                                 ptep_modify_prot_commit(mm, addr, pte, ptent);
90                 } else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
91                         swp_entry_t entry = pte_to_swp_entry(oldpte);
92
93                         if (is_write_migration_entry(entry)) {
94                                 pte_t newpte;
95                                 /*
96                                  * A protection check is difficult so
97                                  * just be safe and disable write
98                                  */
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);
104
105                                 pages++;
106                         }
107                 }
108         } while (pte++, addr += PAGE_SIZE, addr != end);
109         arch_leave_lazy_mmu_mode();
110         pte_unmap_unlock(pte - 1, ptl);
111
112         return pages;
113 }
114
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)
118 {
119         pmd_t *pmd;
120         unsigned long next;
121         unsigned long pages = 0;
122         unsigned long nr_huge_updates = 0;
123
124         pmd = pmd_offset(pud, addr);
125         do {
126                 unsigned long this_pages;
127
128                 next = pmd_addr_end(addr, end);
129                 if (pmd_trans_huge(*pmd)) {
130                         if (next - addr != HPAGE_PMD_SIZE)
131                                 split_huge_page_pmd(vma, addr, pmd);
132                         else {
133                                 int nr_ptes = change_huge_pmd(vma, pmd, addr,
134                                                 newprot, prot_numa);
135
136                                 if (nr_ptes) {
137                                         if (nr_ptes == HPAGE_PMD_NR) {
138                                                 pages += HPAGE_PMD_NR;
139                                                 nr_huge_updates++;
140                                         }
141                                         continue;
142                                 }
143                         }
144                         /* fall through */
145                 }
146                 if (pmd_none_or_clear_bad(pmd))
147                         continue;
148                 this_pages = change_pte_range(vma, pmd, addr, next, newprot,
149                                  dirty_accountable, prot_numa);
150                 pages += this_pages;
151         } while (pmd++, addr = next, addr != end);
152
153         if (nr_huge_updates)
154                 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
155         return pages;
156 }
157
158 static inline unsigned long change_pud_range(struct vm_area_struct *vma,
159                 pgd_t *pgd, unsigned long addr, unsigned long end,
160                 pgprot_t newprot, int dirty_accountable, int prot_numa)
161 {
162         pud_t *pud;
163         unsigned long next;
164         unsigned long pages = 0;
165
166         pud = pud_offset(pgd, addr);
167         do {
168                 next = pud_addr_end(addr, end);
169                 if (pud_none_or_clear_bad(pud))
170                         continue;
171                 pages += change_pmd_range(vma, pud, addr, next, newprot,
172                                  dirty_accountable, prot_numa);
173         } while (pud++, addr = next, addr != end);
174
175         return pages;
176 }
177
178 static unsigned long change_protection_range(struct vm_area_struct *vma,
179                 unsigned long addr, unsigned long end, pgprot_t newprot,
180                 int dirty_accountable, int prot_numa)
181 {
182         struct mm_struct *mm = vma->vm_mm;
183         pgd_t *pgd;
184         unsigned long next;
185         unsigned long start = addr;
186         unsigned long pages = 0;
187
188         BUG_ON(addr >= end);
189         pgd = pgd_offset(mm, addr);
190         flush_cache_range(vma, addr, end);
191         set_tlb_flush_pending(mm);
192         do {
193                 next = pgd_addr_end(addr, end);
194                 if (pgd_none_or_clear_bad(pgd))
195                         continue;
196                 pages += change_pud_range(vma, pgd, addr, next, newprot,
197                                  dirty_accountable, prot_numa);
198         } while (pgd++, addr = next, addr != end);
199
200         /* Only flush the TLB if we actually modified any entries: */
201         if (pages)
202                 flush_tlb_range(vma, start, end);
203         clear_tlb_flush_pending(mm);
204
205         return pages;
206 }
207
208 unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
209                        unsigned long end, pgprot_t newprot,
210                        int dirty_accountable, int prot_numa)
211 {
212         struct mm_struct *mm = vma->vm_mm;
213         unsigned long pages;
214
215         mmu_notifier_invalidate_range_start(mm, start, end);
216         if (is_vm_hugetlb_page(vma))
217                 pages = hugetlb_change_protection(vma, start, end, newprot);
218         else
219                 pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
220         mmu_notifier_invalidate_range_end(mm, start, end);
221
222         return pages;
223 }
224
225 int
226 mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
227         unsigned long start, unsigned long end, unsigned long newflags)
228 {
229         struct mm_struct *mm = vma->vm_mm;
230         unsigned long oldflags = vma->vm_flags;
231         long nrpages = (end - start) >> PAGE_SHIFT;
232         unsigned long charged = 0;
233         pgoff_t pgoff;
234         int error;
235         int dirty_accountable = 0;
236
237         if (newflags == oldflags) {
238                 *pprev = vma;
239                 return 0;
240         }
241
242         /*
243          * If we make a private mapping writable we increase our commit;
244          * but (without finer accounting) cannot reduce our commit if we
245          * make it unwritable again. hugetlb mapping were accounted for
246          * even if read-only so there is no need to account for them here
247          */
248         if (newflags & VM_WRITE) {
249                 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
250                                                 VM_SHARED|VM_NORESERVE))) {
251                         charged = nrpages;
252                         if (security_vm_enough_memory_mm(mm, charged))
253                                 return -ENOMEM;
254                         newflags |= VM_ACCOUNT;
255                 }
256         }
257
258         /*
259          * First try to merge with previous and/or next vma.
260          */
261         pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
262         *pprev = vma_merge(mm, *pprev, start, end, newflags,
263                         vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
264         if (*pprev) {
265                 vma = *pprev;
266                 goto success;
267         }
268
269         *pprev = vma;
270
271         if (start != vma->vm_start) {
272                 error = split_vma(mm, vma, start, 1);
273                 if (error)
274                         goto fail;
275         }
276
277         if (end != vma->vm_end) {
278                 error = split_vma(mm, vma, end, 0);
279                 if (error)
280                         goto fail;
281         }
282
283 success:
284         /*
285          * vm_flags and vm_page_prot are protected by the mmap_sem
286          * held in write mode.
287          */
288         vma->vm_flags = newflags;
289         vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
290                                           vm_get_page_prot(newflags));
291
292         if (vma_wants_writenotify(vma)) {
293                 vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
294                 dirty_accountable = 1;
295         }
296
297         change_protection(vma, start, end, vma->vm_page_prot,
298                           dirty_accountable, 0);
299
300         vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
301         vm_stat_account(mm, newflags, vma->vm_file, nrpages);
302         perf_event_mmap(vma);
303         return 0;
304
305 fail:
306         vm_unacct_memory(charged);
307         return error;
308 }
309
310 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
311                 unsigned long, prot)
312 {
313         unsigned long vm_flags, nstart, end, tmp, reqprot;
314         struct vm_area_struct *vma, *prev;
315         int error = -EINVAL;
316         const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
317         prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
318         if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
319                 return -EINVAL;
320
321         if (start & ~PAGE_MASK)
322                 return -EINVAL;
323         if (!len)
324                 return 0;
325         len = PAGE_ALIGN(len);
326         end = start + len;
327         if (end <= start)
328                 return -ENOMEM;
329         if (!arch_validate_prot(prot))
330                 return -EINVAL;
331
332         reqprot = prot;
333         /*
334          * Does the application expect PROT_READ to imply PROT_EXEC:
335          */
336         if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
337                 prot |= PROT_EXEC;
338
339         vm_flags = calc_vm_prot_bits(prot);
340
341         down_write(&current->mm->mmap_sem);
342
343         vma = find_vma(current->mm, start);
344         error = -ENOMEM;
345         if (!vma)
346                 goto out;
347         prev = vma->vm_prev;
348         if (unlikely(grows & PROT_GROWSDOWN)) {
349                 if (vma->vm_start >= end)
350                         goto out;
351                 start = vma->vm_start;
352                 error = -EINVAL;
353                 if (!(vma->vm_flags & VM_GROWSDOWN))
354                         goto out;
355         } else {
356                 if (vma->vm_start > start)
357                         goto out;
358                 if (unlikely(grows & PROT_GROWSUP)) {
359                         end = vma->vm_end;
360                         error = -EINVAL;
361                         if (!(vma->vm_flags & VM_GROWSUP))
362                                 goto out;
363                 }
364         }
365         if (start > vma->vm_start)
366                 prev = vma;
367
368         for (nstart = start ; ; ) {
369                 unsigned long newflags;
370
371                 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
372
373                 newflags = vm_flags;
374                 newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
375
376                 /* newflags >> 4 shift VM_MAY% in place of VM_% */
377                 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
378                         error = -EACCES;
379                         goto out;
380                 }
381
382                 error = security_file_mprotect(vma, reqprot, prot);
383                 if (error)
384                         goto out;
385
386                 tmp = vma->vm_end;
387                 if (tmp > end)
388                         tmp = end;
389                 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
390                 if (error)
391                         goto out;
392                 nstart = tmp;
393
394                 if (nstart < prev->vm_end)
395                         nstart = prev->vm_end;
396                 if (nstart >= end)
397                         goto out;
398
399                 vma = prev->vm_next;
400                 if (!vma || vma->vm_start != nstart) {
401                         error = -ENOMEM;
402                         goto out;
403                 }
404         }
405 out:
406         up_write(&current->mm->mmap_sem);
407         return error;
408 }