arm64: dts: imx8mm: Drop deprecated regulator-compatible from Variscite VAR-SOM-MX8MM
[linux-2.6-microblaze.git] / mm / mprotect.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  mm/mprotect.c
4  *
5  *  (C) Copyright 1994 Linus Torvalds
6  *  (C) Copyright 2002 Christoph Hellwig
7  *
8  *  Address space accounting code       <alan@lxorguk.ukuu.org.uk>
9  *  (C) Copyright 2002 Red Hat Inc, All Rights Reserved
10  */
11
12 #include <linux/pagewalk.h>
13 #include <linux/hugetlb.h>
14 #include <linux/shm.h>
15 #include <linux/mman.h>
16 #include <linux/fs.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 <linux/mmu_notifier.h>
25 #include <linux/migrate.h>
26 #include <linux/perf_event.h>
27 #include <linux/pkeys.h>
28 #include <linux/ksm.h>
29 #include <linux/uaccess.h>
30 #include <linux/mm_inline.h>
31 #include <linux/pgtable.h>
32 #include <linux/sched/sysctl.h>
33 #include <linux/userfaultfd_k.h>
34 #include <linux/memory-tiers.h>
35 #include <asm/cacheflush.h>
36 #include <asm/mmu_context.h>
37 #include <asm/tlbflush.h>
38 #include <asm/tlb.h>
39
40 #include "internal.h"
41
42 bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
43                              pte_t pte)
44 {
45         struct page *page;
46
47         if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE)))
48                 return false;
49
50         /* Don't touch entries that are not even readable. */
51         if (pte_protnone(pte))
52                 return false;
53
54         /* Do we need write faults for softdirty tracking? */
55         if (vma_soft_dirty_enabled(vma) && !pte_soft_dirty(pte))
56                 return false;
57
58         /* Do we need write faults for uffd-wp tracking? */
59         if (userfaultfd_pte_wp(vma, pte))
60                 return false;
61
62         if (!(vma->vm_flags & VM_SHARED)) {
63                 /*
64                  * Writable MAP_PRIVATE mapping: We can only special-case on
65                  * exclusive anonymous pages, because we know that our
66                  * write-fault handler similarly would map them writable without
67                  * any additional checks while holding the PT lock.
68                  */
69                 page = vm_normal_page(vma, addr, pte);
70                 return page && PageAnon(page) && PageAnonExclusive(page);
71         }
72
73         /*
74          * Writable MAP_SHARED mapping: "clean" might indicate that the FS still
75          * needs a real write-fault for writenotify
76          * (see vma_wants_writenotify()). If "dirty", the assumption is that the
77          * FS was already notified and we can simply mark the PTE writable
78          * just like the write-fault handler would do.
79          */
80         return pte_dirty(pte);
81 }
82
83 static unsigned long change_pte_range(struct mmu_gather *tlb,
84                 struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr,
85                 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
86 {
87         pte_t *pte, oldpte;
88         spinlock_t *ptl;
89         unsigned long pages = 0;
90         int target_node = NUMA_NO_NODE;
91         bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
92         bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
93         bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
94
95         tlb_change_page_size(tlb, PAGE_SIZE);
96
97         /*
98          * Can be called with only the mmap_lock for reading by
99          * prot_numa so we must check the pmd isn't constantly
100          * changing from under us from pmd_none to pmd_trans_huge
101          * and/or the other way around.
102          */
103         if (pmd_trans_unstable(pmd))
104                 return 0;
105
106         /*
107          * The pmd points to a regular pte so the pmd can't change
108          * from under us even if the mmap_lock is only hold for
109          * reading.
110          */
111         pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
112
113         /* Get target node for single threaded private VMAs */
114         if (prot_numa && !(vma->vm_flags & VM_SHARED) &&
115             atomic_read(&vma->vm_mm->mm_users) == 1)
116                 target_node = numa_node_id();
117
118         flush_tlb_batched_pending(vma->vm_mm);
119         arch_enter_lazy_mmu_mode();
120         do {
121                 oldpte = *pte;
122                 if (pte_present(oldpte)) {
123                         pte_t ptent;
124
125                         /*
126                          * Avoid trapping faults against the zero or KSM
127                          * pages. See similar comment in change_huge_pmd.
128                          */
129                         if (prot_numa) {
130                                 struct page *page;
131                                 int nid;
132                                 bool toptier;
133
134                                 /* Avoid TLB flush if possible */
135                                 if (pte_protnone(oldpte))
136                                         continue;
137
138                                 page = vm_normal_page(vma, addr, oldpte);
139                                 if (!page || is_zone_device_page(page) || PageKsm(page))
140                                         continue;
141
142                                 /* Also skip shared copy-on-write pages */
143                                 if (is_cow_mapping(vma->vm_flags) &&
144                                     page_count(page) != 1)
145                                         continue;
146
147                                 /*
148                                  * While migration can move some dirty pages,
149                                  * it cannot move them all from MIGRATE_ASYNC
150                                  * context.
151                                  */
152                                 if (page_is_file_lru(page) && PageDirty(page))
153                                         continue;
154
155                                 /*
156                                  * Don't mess with PTEs if page is already on the node
157                                  * a single-threaded process is running on.
158                                  */
159                                 nid = page_to_nid(page);
160                                 if (target_node == nid)
161                                         continue;
162                                 toptier = node_is_toptier(nid);
163
164                                 /*
165                                  * Skip scanning top tier node if normal numa
166                                  * balancing is disabled
167                                  */
168                                 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
169                                     toptier)
170                                         continue;
171                                 if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING &&
172                                     !toptier)
173                                         xchg_page_access_time(page,
174                                                 jiffies_to_msecs(jiffies));
175                         }
176
177                         oldpte = ptep_modify_prot_start(vma, addr, pte);
178                         ptent = pte_modify(oldpte, newprot);
179
180                         if (uffd_wp) {
181                                 ptent = pte_wrprotect(ptent);
182                                 ptent = pte_mkuffd_wp(ptent);
183                         } else if (uffd_wp_resolve) {
184                                 ptent = pte_clear_uffd_wp(ptent);
185                         }
186
187                         /*
188                          * In some writable, shared mappings, we might want
189                          * to catch actual write access -- see
190                          * vma_wants_writenotify().
191                          *
192                          * In all writable, private mappings, we have to
193                          * properly handle COW.
194                          *
195                          * In both cases, we can sometimes still change PTEs
196                          * writable and avoid the write-fault handler, for
197                          * example, if a PTE is already dirty and no other
198                          * COW or special handling is required.
199                          */
200                         if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) &&
201                             !pte_write(ptent) &&
202                             can_change_pte_writable(vma, addr, ptent))
203                                 ptent = pte_mkwrite(ptent);
204
205                         ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent);
206                         if (pte_needs_flush(oldpte, ptent))
207                                 tlb_flush_pte_range(tlb, addr, PAGE_SIZE);
208                         pages++;
209                 } else if (is_swap_pte(oldpte)) {
210                         swp_entry_t entry = pte_to_swp_entry(oldpte);
211                         pte_t newpte;
212
213                         if (is_writable_migration_entry(entry)) {
214                                 struct page *page = pfn_swap_entry_to_page(entry);
215
216                                 /*
217                                  * A protection check is difficult so
218                                  * just be safe and disable write
219                                  */
220                                 if (PageAnon(page))
221                                         entry = make_readable_exclusive_migration_entry(
222                                                              swp_offset(entry));
223                                 else
224                                         entry = make_readable_migration_entry(swp_offset(entry));
225                                 newpte = swp_entry_to_pte(entry);
226                                 if (pte_swp_soft_dirty(oldpte))
227                                         newpte = pte_swp_mksoft_dirty(newpte);
228                                 if (pte_swp_uffd_wp(oldpte))
229                                         newpte = pte_swp_mkuffd_wp(newpte);
230                         } else if (is_writable_device_private_entry(entry)) {
231                                 /*
232                                  * We do not preserve soft-dirtiness. See
233                                  * copy_one_pte() for explanation.
234                                  */
235                                 entry = make_readable_device_private_entry(
236                                                         swp_offset(entry));
237                                 newpte = swp_entry_to_pte(entry);
238                                 if (pte_swp_uffd_wp(oldpte))
239                                         newpte = pte_swp_mkuffd_wp(newpte);
240                         } else if (is_writable_device_exclusive_entry(entry)) {
241                                 entry = make_readable_device_exclusive_entry(
242                                                         swp_offset(entry));
243                                 newpte = swp_entry_to_pte(entry);
244                                 if (pte_swp_soft_dirty(oldpte))
245                                         newpte = pte_swp_mksoft_dirty(newpte);
246                                 if (pte_swp_uffd_wp(oldpte))
247                                         newpte = pte_swp_mkuffd_wp(newpte);
248                         } else if (pte_marker_entry_uffd_wp(entry)) {
249                                 /*
250                                  * If this is uffd-wp pte marker and we'd like
251                                  * to unprotect it, drop it; the next page
252                                  * fault will trigger without uffd trapping.
253                                  */
254                                 if (uffd_wp_resolve) {
255                                         pte_clear(vma->vm_mm, addr, pte);
256                                         pages++;
257                                 }
258                                 continue;
259                         } else {
260                                 newpte = oldpte;
261                         }
262
263                         if (uffd_wp)
264                                 newpte = pte_swp_mkuffd_wp(newpte);
265                         else if (uffd_wp_resolve)
266                                 newpte = pte_swp_clear_uffd_wp(newpte);
267
268                         if (!pte_same(oldpte, newpte)) {
269                                 set_pte_at(vma->vm_mm, addr, pte, newpte);
270                                 pages++;
271                         }
272                 } else {
273                         /* It must be an none page, or what else?.. */
274                         WARN_ON_ONCE(!pte_none(oldpte));
275                         if (unlikely(uffd_wp && !vma_is_anonymous(vma))) {
276                                 /*
277                                  * For file-backed mem, we need to be able to
278                                  * wr-protect a none pte, because even if the
279                                  * pte is none, the page/swap cache could
280                                  * exist.  Doing that by install a marker.
281                                  */
282                                 set_pte_at(vma->vm_mm, addr, pte,
283                                            make_pte_marker(PTE_MARKER_UFFD_WP));
284                                 pages++;
285                         }
286                 }
287         } while (pte++, addr += PAGE_SIZE, addr != end);
288         arch_leave_lazy_mmu_mode();
289         pte_unmap_unlock(pte - 1, ptl);
290
291         return pages;
292 }
293
294 /*
295  * Used when setting automatic NUMA hinting protection where it is
296  * critical that a numa hinting PMD is not confused with a bad PMD.
297  */
298 static inline int pmd_none_or_clear_bad_unless_trans_huge(pmd_t *pmd)
299 {
300         pmd_t pmdval = pmdp_get_lockless(pmd);
301
302         /* See pmd_none_or_trans_huge_or_clear_bad for info on barrier */
303 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
304         barrier();
305 #endif
306
307         if (pmd_none(pmdval))
308                 return 1;
309         if (pmd_trans_huge(pmdval))
310                 return 0;
311         if (unlikely(pmd_bad(pmdval))) {
312                 pmd_clear_bad(pmd);
313                 return 1;
314         }
315
316         return 0;
317 }
318
319 /* Return true if we're uffd wr-protecting file-backed memory, or false */
320 static inline bool
321 uffd_wp_protect_file(struct vm_area_struct *vma, unsigned long cp_flags)
322 {
323         return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma);
324 }
325
326 /*
327  * If wr-protecting the range for file-backed, populate pgtable for the case
328  * when pgtable is empty but page cache exists.  When {pte|pmd|...}_alloc()
329  * failed it means no memory, we don't have a better option but stop.
330  */
331 #define  change_pmd_prepare(vma, pmd, cp_flags)                         \
332         do {                                                            \
333                 if (unlikely(uffd_wp_protect_file(vma, cp_flags))) {    \
334                         if (WARN_ON_ONCE(pte_alloc(vma->vm_mm, pmd)))   \
335                                 break;                                  \
336                 }                                                       \
337         } while (0)
338 /*
339  * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to
340  * have separate change_pmd_prepare() because pte_alloc() returns 0 on success,
341  * while {pmd|pud|p4d}_alloc() returns the valid pointer on success.
342  */
343 #define  change_prepare(vma, high, low, addr, cp_flags)                 \
344         do {                                                            \
345                 if (unlikely(uffd_wp_protect_file(vma, cp_flags))) {    \
346                         low##_t *p = low##_alloc(vma->vm_mm, high, addr); \
347                         if (WARN_ON_ONCE(p == NULL))                    \
348                                 break;                                  \
349                 }                                                       \
350         } while (0)
351
352 static inline unsigned long change_pmd_range(struct mmu_gather *tlb,
353                 struct vm_area_struct *vma, pud_t *pud, unsigned long addr,
354                 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
355 {
356         pmd_t *pmd;
357         unsigned long next;
358         unsigned long pages = 0;
359         unsigned long nr_huge_updates = 0;
360         struct mmu_notifier_range range;
361
362         range.start = 0;
363
364         pmd = pmd_offset(pud, addr);
365         do {
366                 unsigned long this_pages;
367
368                 next = pmd_addr_end(addr, end);
369
370                 change_pmd_prepare(vma, pmd, cp_flags);
371                 /*
372                  * Automatic NUMA balancing walks the tables with mmap_lock
373                  * held for read. It's possible a parallel update to occur
374                  * between pmd_trans_huge() and a pmd_none_or_clear_bad()
375                  * check leading to a false positive and clearing.
376                  * Hence, it's necessary to atomically read the PMD value
377                  * for all the checks.
378                  */
379                 if (!is_swap_pmd(*pmd) && !pmd_devmap(*pmd) &&
380                      pmd_none_or_clear_bad_unless_trans_huge(pmd))
381                         goto next;
382
383                 /* invoke the mmu notifier if the pmd is populated */
384                 if (!range.start) {
385                         mmu_notifier_range_init(&range,
386                                 MMU_NOTIFY_PROTECTION_VMA, 0,
387                                 vma, vma->vm_mm, addr, end);
388                         mmu_notifier_invalidate_range_start(&range);
389                 }
390
391                 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
392                         if ((next - addr != HPAGE_PMD_SIZE) ||
393                             uffd_wp_protect_file(vma, cp_flags)) {
394                                 __split_huge_pmd(vma, pmd, addr, false, NULL);
395                                 /*
396                                  * For file-backed, the pmd could have been
397                                  * cleared; make sure pmd populated if
398                                  * necessary, then fall-through to pte level.
399                                  */
400                                 change_pmd_prepare(vma, pmd, cp_flags);
401                         } else {
402                                 /*
403                                  * change_huge_pmd() does not defer TLB flushes,
404                                  * so no need to propagate the tlb argument.
405                                  */
406                                 int nr_ptes = change_huge_pmd(tlb, vma, pmd,
407                                                 addr, newprot, cp_flags);
408
409                                 if (nr_ptes) {
410                                         if (nr_ptes == HPAGE_PMD_NR) {
411                                                 pages += HPAGE_PMD_NR;
412                                                 nr_huge_updates++;
413                                         }
414
415                                         /* huge pmd was handled */
416                                         goto next;
417                                 }
418                         }
419                         /* fall through, the trans huge pmd just split */
420                 }
421                 this_pages = change_pte_range(tlb, vma, pmd, addr, next,
422                                               newprot, cp_flags);
423                 pages += this_pages;
424 next:
425                 cond_resched();
426         } while (pmd++, addr = next, addr != end);
427
428         if (range.start)
429                 mmu_notifier_invalidate_range_end(&range);
430
431         if (nr_huge_updates)
432                 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
433         return pages;
434 }
435
436 static inline unsigned long change_pud_range(struct mmu_gather *tlb,
437                 struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr,
438                 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
439 {
440         pud_t *pud;
441         unsigned long next;
442         unsigned long pages = 0;
443
444         pud = pud_offset(p4d, addr);
445         do {
446                 next = pud_addr_end(addr, end);
447                 change_prepare(vma, pud, pmd, addr, cp_flags);
448                 if (pud_none_or_clear_bad(pud))
449                         continue;
450                 pages += change_pmd_range(tlb, vma, pud, addr, next, newprot,
451                                           cp_flags);
452         } while (pud++, addr = next, addr != end);
453
454         return pages;
455 }
456
457 static inline unsigned long change_p4d_range(struct mmu_gather *tlb,
458                 struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr,
459                 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
460 {
461         p4d_t *p4d;
462         unsigned long next;
463         unsigned long pages = 0;
464
465         p4d = p4d_offset(pgd, addr);
466         do {
467                 next = p4d_addr_end(addr, end);
468                 change_prepare(vma, p4d, pud, addr, cp_flags);
469                 if (p4d_none_or_clear_bad(p4d))
470                         continue;
471                 pages += change_pud_range(tlb, vma, p4d, addr, next, newprot,
472                                           cp_flags);
473         } while (p4d++, addr = next, addr != end);
474
475         return pages;
476 }
477
478 static unsigned long change_protection_range(struct mmu_gather *tlb,
479                 struct vm_area_struct *vma, unsigned long addr,
480                 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
481 {
482         struct mm_struct *mm = vma->vm_mm;
483         pgd_t *pgd;
484         unsigned long next;
485         unsigned long pages = 0;
486
487         BUG_ON(addr >= end);
488         pgd = pgd_offset(mm, addr);
489         tlb_start_vma(tlb, vma);
490         do {
491                 next = pgd_addr_end(addr, end);
492                 change_prepare(vma, pgd, p4d, addr, cp_flags);
493                 if (pgd_none_or_clear_bad(pgd))
494                         continue;
495                 pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot,
496                                           cp_flags);
497         } while (pgd++, addr = next, addr != end);
498
499         tlb_end_vma(tlb, vma);
500
501         return pages;
502 }
503
504 unsigned long change_protection(struct mmu_gather *tlb,
505                        struct vm_area_struct *vma, unsigned long start,
506                        unsigned long end, pgprot_t newprot,
507                        unsigned long cp_flags)
508 {
509         unsigned long pages;
510
511         BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
512
513         if (is_vm_hugetlb_page(vma))
514                 pages = hugetlb_change_protection(vma, start, end, newprot,
515                                                   cp_flags);
516         else
517                 pages = change_protection_range(tlb, vma, start, end, newprot,
518                                                 cp_flags);
519
520         return pages;
521 }
522
523 static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
524                                unsigned long next, struct mm_walk *walk)
525 {
526         return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
527                 0 : -EACCES;
528 }
529
530 static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
531                                    unsigned long addr, unsigned long next,
532                                    struct mm_walk *walk)
533 {
534         return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
535                 0 : -EACCES;
536 }
537
538 static int prot_none_test(unsigned long addr, unsigned long next,
539                           struct mm_walk *walk)
540 {
541         return 0;
542 }
543
544 static const struct mm_walk_ops prot_none_walk_ops = {
545         .pte_entry              = prot_none_pte_entry,
546         .hugetlb_entry          = prot_none_hugetlb_entry,
547         .test_walk              = prot_none_test,
548 };
549
550 int
551 mprotect_fixup(struct mmu_gather *tlb, struct vm_area_struct *vma,
552                struct vm_area_struct **pprev, unsigned long start,
553                unsigned long end, unsigned long newflags)
554 {
555         struct mm_struct *mm = vma->vm_mm;
556         unsigned long oldflags = vma->vm_flags;
557         long nrpages = (end - start) >> PAGE_SHIFT;
558         unsigned int mm_cp_flags = 0;
559         unsigned long charged = 0;
560         pgoff_t pgoff;
561         int error;
562
563         if (newflags == oldflags) {
564                 *pprev = vma;
565                 return 0;
566         }
567
568         /*
569          * Do PROT_NONE PFN permission checks here when we can still
570          * bail out without undoing a lot of state. This is a rather
571          * uncommon case, so doesn't need to be very optimized.
572          */
573         if (arch_has_pfn_modify_check() &&
574             (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
575             (newflags & VM_ACCESS_FLAGS) == 0) {
576                 pgprot_t new_pgprot = vm_get_page_prot(newflags);
577
578                 error = walk_page_range(current->mm, start, end,
579                                 &prot_none_walk_ops, &new_pgprot);
580                 if (error)
581                         return error;
582         }
583
584         /*
585          * If we make a private mapping writable we increase our commit;
586          * but (without finer accounting) cannot reduce our commit if we
587          * make it unwritable again. hugetlb mapping were accounted for
588          * even if read-only so there is no need to account for them here
589          */
590         if (newflags & VM_WRITE) {
591                 /* Check space limits when area turns into data. */
592                 if (!may_expand_vm(mm, newflags, nrpages) &&
593                                 may_expand_vm(mm, oldflags, nrpages))
594                         return -ENOMEM;
595                 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
596                                                 VM_SHARED|VM_NORESERVE))) {
597                         charged = nrpages;
598                         if (security_vm_enough_memory_mm(mm, charged))
599                                 return -ENOMEM;
600                         newflags |= VM_ACCOUNT;
601                 }
602         }
603
604         /*
605          * First try to merge with previous and/or next vma.
606          */
607         pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
608         *pprev = vma_merge(mm, *pprev, start, end, newflags,
609                            vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
610                            vma->vm_userfaultfd_ctx, anon_vma_name(vma));
611         if (*pprev) {
612                 vma = *pprev;
613                 VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY);
614                 goto success;
615         }
616
617         *pprev = vma;
618
619         if (start != vma->vm_start) {
620                 error = split_vma(mm, vma, start, 1);
621                 if (error)
622                         goto fail;
623         }
624
625         if (end != vma->vm_end) {
626                 error = split_vma(mm, vma, end, 0);
627                 if (error)
628                         goto fail;
629         }
630
631 success:
632         /*
633          * vm_flags and vm_page_prot are protected by the mmap_lock
634          * held in write mode.
635          */
636         vma->vm_flags = newflags;
637         if (vma_wants_manual_pte_write_upgrade(vma))
638                 mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE;
639         vma_set_page_prot(vma);
640
641         change_protection(tlb, vma, start, end, vma->vm_page_prot, mm_cp_flags);
642
643         /*
644          * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
645          * fault on access.
646          */
647         if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
648                         (newflags & VM_WRITE)) {
649                 populate_vma_page_range(vma, start, end, NULL);
650         }
651
652         vm_stat_account(mm, oldflags, -nrpages);
653         vm_stat_account(mm, newflags, nrpages);
654         perf_event_mmap(vma);
655         return 0;
656
657 fail:
658         vm_unacct_memory(charged);
659         return error;
660 }
661
662 /*
663  * pkey==-1 when doing a legacy mprotect()
664  */
665 static int do_mprotect_pkey(unsigned long start, size_t len,
666                 unsigned long prot, int pkey)
667 {
668         unsigned long nstart, end, tmp, reqprot;
669         struct vm_area_struct *vma, *prev;
670         int error;
671         const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
672         const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
673                                 (prot & PROT_READ);
674         struct mmu_gather tlb;
675         MA_STATE(mas, &current->mm->mm_mt, 0, 0);
676
677         start = untagged_addr(start);
678
679         prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
680         if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
681                 return -EINVAL;
682
683         if (start & ~PAGE_MASK)
684                 return -EINVAL;
685         if (!len)
686                 return 0;
687         len = PAGE_ALIGN(len);
688         end = start + len;
689         if (end <= start)
690                 return -ENOMEM;
691         if (!arch_validate_prot(prot, start))
692                 return -EINVAL;
693
694         reqprot = prot;
695
696         if (mmap_write_lock_killable(current->mm))
697                 return -EINTR;
698
699         /*
700          * If userspace did not allocate the pkey, do not let
701          * them use it here.
702          */
703         error = -EINVAL;
704         if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
705                 goto out;
706
707         mas_set(&mas, start);
708         vma = mas_find(&mas, ULONG_MAX);
709         error = -ENOMEM;
710         if (!vma)
711                 goto out;
712
713         if (unlikely(grows & PROT_GROWSDOWN)) {
714                 if (vma->vm_start >= end)
715                         goto out;
716                 start = vma->vm_start;
717                 error = -EINVAL;
718                 if (!(vma->vm_flags & VM_GROWSDOWN))
719                         goto out;
720         } else {
721                 if (vma->vm_start > start)
722                         goto out;
723                 if (unlikely(grows & PROT_GROWSUP)) {
724                         end = vma->vm_end;
725                         error = -EINVAL;
726                         if (!(vma->vm_flags & VM_GROWSUP))
727                                 goto out;
728                 }
729         }
730
731         if (start > vma->vm_start)
732                 prev = vma;
733         else
734                 prev = mas_prev(&mas, 0);
735
736         tlb_gather_mmu(&tlb, current->mm);
737         for (nstart = start ; ; ) {
738                 unsigned long mask_off_old_flags;
739                 unsigned long newflags;
740                 int new_vma_pkey;
741
742                 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
743
744                 /* Does the application expect PROT_READ to imply PROT_EXEC */
745                 if (rier && (vma->vm_flags & VM_MAYEXEC))
746                         prot |= PROT_EXEC;
747
748                 /*
749                  * Each mprotect() call explicitly passes r/w/x permissions.
750                  * If a permission is not passed to mprotect(), it must be
751                  * cleared from the VMA.
752                  */
753                 mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR;
754
755                 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
756                 newflags = calc_vm_prot_bits(prot, new_vma_pkey);
757                 newflags |= (vma->vm_flags & ~mask_off_old_flags);
758
759                 /* newflags >> 4 shift VM_MAY% in place of VM_% */
760                 if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) {
761                         error = -EACCES;
762                         break;
763                 }
764
765                 /* Allow architectures to sanity-check the new flags */
766                 if (!arch_validate_flags(newflags)) {
767                         error = -EINVAL;
768                         break;
769                 }
770
771                 error = security_file_mprotect(vma, reqprot, prot);
772                 if (error)
773                         break;
774
775                 tmp = vma->vm_end;
776                 if (tmp > end)
777                         tmp = end;
778
779                 if (vma->vm_ops && vma->vm_ops->mprotect) {
780                         error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags);
781                         if (error)
782                                 break;
783                 }
784
785                 error = mprotect_fixup(&tlb, vma, &prev, nstart, tmp, newflags);
786                 if (error)
787                         break;
788
789                 nstart = tmp;
790
791                 if (nstart < prev->vm_end)
792                         nstart = prev->vm_end;
793                 if (nstart >= end)
794                         break;
795
796                 vma = find_vma(current->mm, prev->vm_end);
797                 if (!vma || vma->vm_start != nstart) {
798                         error = -ENOMEM;
799                         break;
800                 }
801                 prot = reqprot;
802         }
803         tlb_finish_mmu(&tlb);
804 out:
805         mmap_write_unlock(current->mm);
806         return error;
807 }
808
809 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
810                 unsigned long, prot)
811 {
812         return do_mprotect_pkey(start, len, prot, -1);
813 }
814
815 #ifdef CONFIG_ARCH_HAS_PKEYS
816
817 SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
818                 unsigned long, prot, int, pkey)
819 {
820         return do_mprotect_pkey(start, len, prot, pkey);
821 }
822
823 SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
824 {
825         int pkey;
826         int ret;
827
828         /* No flags supported yet. */
829         if (flags)
830                 return -EINVAL;
831         /* check for unsupported init values */
832         if (init_val & ~PKEY_ACCESS_MASK)
833                 return -EINVAL;
834
835         mmap_write_lock(current->mm);
836         pkey = mm_pkey_alloc(current->mm);
837
838         ret = -ENOSPC;
839         if (pkey == -1)
840                 goto out;
841
842         ret = arch_set_user_pkey_access(current, pkey, init_val);
843         if (ret) {
844                 mm_pkey_free(current->mm, pkey);
845                 goto out;
846         }
847         ret = pkey;
848 out:
849         mmap_write_unlock(current->mm);
850         return ret;
851 }
852
853 SYSCALL_DEFINE1(pkey_free, int, pkey)
854 {
855         int ret;
856
857         mmap_write_lock(current->mm);
858         ret = mm_pkey_free(current->mm, pkey);
859         mmap_write_unlock(current->mm);
860
861         /*
862          * We could provide warnings or errors if any VMA still
863          * has the pkey set here.
864          */
865         return ret;
866 }
867
868 #endif /* CONFIG_ARCH_HAS_PKEYS */