Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
[platform/kernel/linux-rpi.git] / mm / memory.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/mm/memory.c
4  *
5  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
6  */
7
8 /*
9  * demand-loading started 01.12.91 - seems it is high on the list of
10  * things wanted, and it should be easy to implement. - Linus
11  */
12
13 /*
14  * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
15  * pages started 02.12.91, seems to work. - Linus.
16  *
17  * Tested sharing by executing about 30 /bin/sh: under the old kernel it
18  * would have taken more than the 6M I have free, but it worked well as
19  * far as I could see.
20  *
21  * Also corrected some "invalidate()"s - I wasn't doing enough of them.
22  */
23
24 /*
25  * Real VM (paging to/from disk) started 18.12.91. Much more work and
26  * thought has to go into this. Oh, well..
27  * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
28  *              Found it. Everything seems to work now.
29  * 20.12.91  -  Ok, making the swap-device changeable like the root.
30  */
31
32 /*
33  * 05.04.94  -  Multi-page memory management added for v1.1.
34  *              Idea by Alex Bligh (alex@cconcepts.co.uk)
35  *
36  * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
37  *              (Gerhard.Wichert@pdb.siemens.de)
38  *
39  * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
40  */
41
42 #include <linux/kernel_stat.h>
43 #include <linux/mm.h>
44 #include <linux/sched/mm.h>
45 #include <linux/sched/coredump.h>
46 #include <linux/sched/numa_balancing.h>
47 #include <linux/sched/task.h>
48 #include <linux/hugetlb.h>
49 #include <linux/mman.h>
50 #include <linux/swap.h>
51 #include <linux/highmem.h>
52 #include <linux/pagemap.h>
53 #include <linux/memremap.h>
54 #include <linux/ksm.h>
55 #include <linux/rmap.h>
56 #include <linux/export.h>
57 #include <linux/delayacct.h>
58 #include <linux/init.h>
59 #include <linux/pfn_t.h>
60 #include <linux/writeback.h>
61 #include <linux/memcontrol.h>
62 #include <linux/mmu_notifier.h>
63 #include <linux/swapops.h>
64 #include <linux/elf.h>
65 #include <linux/gfp.h>
66 #include <linux/migrate.h>
67 #include <linux/string.h>
68 #include <linux/debugfs.h>
69 #include <linux/userfaultfd_k.h>
70 #include <linux/dax.h>
71 #include <linux/oom.h>
72 #include <linux/numa.h>
73 #include <linux/perf_event.h>
74 #include <linux/ptrace.h>
75 #include <linux/vmalloc.h>
76
77 #include <trace/events/kmem.h>
78
79 #include <asm/io.h>
80 #include <asm/mmu_context.h>
81 #include <asm/pgalloc.h>
82 #include <linux/uaccess.h>
83 #include <asm/tlb.h>
84 #include <asm/tlbflush.h>
85
86 #include "pgalloc-track.h"
87 #include "internal.h"
88
89 #if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST)
90 #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
91 #endif
92
93 #ifndef CONFIG_NUMA
94 unsigned long max_mapnr;
95 EXPORT_SYMBOL(max_mapnr);
96
97 struct page *mem_map;
98 EXPORT_SYMBOL(mem_map);
99 #endif
100
101 /*
102  * A number of key systems in x86 including ioremap() rely on the assumption
103  * that high_memory defines the upper bound on direct map memory, then end
104  * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
105  * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
106  * and ZONE_HIGHMEM.
107  */
108 void *high_memory;
109 EXPORT_SYMBOL(high_memory);
110
111 /*
112  * Randomize the address space (stacks, mmaps, brk, etc.).
113  *
114  * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
115  *   as ancient (libc5 based) binaries can segfault. )
116  */
117 int randomize_va_space __read_mostly =
118 #ifdef CONFIG_COMPAT_BRK
119                                         1;
120 #else
121                                         2;
122 #endif
123
124 #ifndef arch_faults_on_old_pte
125 static inline bool arch_faults_on_old_pte(void)
126 {
127         /*
128          * Those arches which don't have hw access flag feature need to
129          * implement their own helper. By default, "true" means pagefault
130          * will be hit on old pte.
131          */
132         return true;
133 }
134 #endif
135
136 #ifndef arch_wants_old_prefaulted_pte
137 static inline bool arch_wants_old_prefaulted_pte(void)
138 {
139         /*
140          * Transitioning a PTE from 'old' to 'young' can be expensive on
141          * some architectures, even if it's performed in hardware. By
142          * default, "false" means prefaulted entries will be 'young'.
143          */
144         return false;
145 }
146 #endif
147
148 static int __init disable_randmaps(char *s)
149 {
150         randomize_va_space = 0;
151         return 1;
152 }
153 __setup("norandmaps", disable_randmaps);
154
155 unsigned long zero_pfn __read_mostly;
156 EXPORT_SYMBOL(zero_pfn);
157
158 unsigned long highest_memmap_pfn __read_mostly;
159
160 /*
161  * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
162  */
163 static int __init init_zero_pfn(void)
164 {
165         zero_pfn = page_to_pfn(ZERO_PAGE(0));
166         return 0;
167 }
168 early_initcall(init_zero_pfn);
169
170 void mm_trace_rss_stat(struct mm_struct *mm, int member, long count)
171 {
172         trace_rss_stat(mm, member, count);
173 }
174
175 #if defined(SPLIT_RSS_COUNTING)
176
177 void sync_mm_rss(struct mm_struct *mm)
178 {
179         int i;
180
181         for (i = 0; i < NR_MM_COUNTERS; i++) {
182                 if (current->rss_stat.count[i]) {
183                         add_mm_counter(mm, i, current->rss_stat.count[i]);
184                         current->rss_stat.count[i] = 0;
185                 }
186         }
187         current->rss_stat.events = 0;
188 }
189
190 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
191 {
192         struct task_struct *task = current;
193
194         if (likely(task->mm == mm))
195                 task->rss_stat.count[member] += val;
196         else
197                 add_mm_counter(mm, member, val);
198 }
199 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
200 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
201
202 /* sync counter once per 64 page faults */
203 #define TASK_RSS_EVENTS_THRESH  (64)
204 static void check_sync_rss_stat(struct task_struct *task)
205 {
206         if (unlikely(task != current))
207                 return;
208         if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
209                 sync_mm_rss(task->mm);
210 }
211 #else /* SPLIT_RSS_COUNTING */
212
213 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
214 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
215
216 static void check_sync_rss_stat(struct task_struct *task)
217 {
218 }
219
220 #endif /* SPLIT_RSS_COUNTING */
221
222 /*
223  * Note: this doesn't free the actual pages themselves. That
224  * has been handled earlier when unmapping all the memory regions.
225  */
226 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
227                            unsigned long addr)
228 {
229         pgtable_t token = pmd_pgtable(*pmd);
230         pmd_clear(pmd);
231         pte_free_tlb(tlb, token, addr);
232         mm_dec_nr_ptes(tlb->mm);
233 }
234
235 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
236                                 unsigned long addr, unsigned long end,
237                                 unsigned long floor, unsigned long ceiling)
238 {
239         pmd_t *pmd;
240         unsigned long next;
241         unsigned long start;
242
243         start = addr;
244         pmd = pmd_offset(pud, addr);
245         do {
246                 next = pmd_addr_end(addr, end);
247                 if (pmd_none_or_clear_bad(pmd))
248                         continue;
249                 free_pte_range(tlb, pmd, addr);
250         } while (pmd++, addr = next, addr != end);
251
252         start &= PUD_MASK;
253         if (start < floor)
254                 return;
255         if (ceiling) {
256                 ceiling &= PUD_MASK;
257                 if (!ceiling)
258                         return;
259         }
260         if (end - 1 > ceiling - 1)
261                 return;
262
263         pmd = pmd_offset(pud, start);
264         pud_clear(pud);
265         pmd_free_tlb(tlb, pmd, start);
266         mm_dec_nr_pmds(tlb->mm);
267 }
268
269 static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
270                                 unsigned long addr, unsigned long end,
271                                 unsigned long floor, unsigned long ceiling)
272 {
273         pud_t *pud;
274         unsigned long next;
275         unsigned long start;
276
277         start = addr;
278         pud = pud_offset(p4d, addr);
279         do {
280                 next = pud_addr_end(addr, end);
281                 if (pud_none_or_clear_bad(pud))
282                         continue;
283                 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
284         } while (pud++, addr = next, addr != end);
285
286         start &= P4D_MASK;
287         if (start < floor)
288                 return;
289         if (ceiling) {
290                 ceiling &= P4D_MASK;
291                 if (!ceiling)
292                         return;
293         }
294         if (end - 1 > ceiling - 1)
295                 return;
296
297         pud = pud_offset(p4d, start);
298         p4d_clear(p4d);
299         pud_free_tlb(tlb, pud, start);
300         mm_dec_nr_puds(tlb->mm);
301 }
302
303 static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
304                                 unsigned long addr, unsigned long end,
305                                 unsigned long floor, unsigned long ceiling)
306 {
307         p4d_t *p4d;
308         unsigned long next;
309         unsigned long start;
310
311         start = addr;
312         p4d = p4d_offset(pgd, addr);
313         do {
314                 next = p4d_addr_end(addr, end);
315                 if (p4d_none_or_clear_bad(p4d))
316                         continue;
317                 free_pud_range(tlb, p4d, addr, next, floor, ceiling);
318         } while (p4d++, addr = next, addr != end);
319
320         start &= PGDIR_MASK;
321         if (start < floor)
322                 return;
323         if (ceiling) {
324                 ceiling &= PGDIR_MASK;
325                 if (!ceiling)
326                         return;
327         }
328         if (end - 1 > ceiling - 1)
329                 return;
330
331         p4d = p4d_offset(pgd, start);
332         pgd_clear(pgd);
333         p4d_free_tlb(tlb, p4d, start);
334 }
335
336 /*
337  * This function frees user-level page tables of a process.
338  */
339 void free_pgd_range(struct mmu_gather *tlb,
340                         unsigned long addr, unsigned long end,
341                         unsigned long floor, unsigned long ceiling)
342 {
343         pgd_t *pgd;
344         unsigned long next;
345
346         /*
347          * The next few lines have given us lots of grief...
348          *
349          * Why are we testing PMD* at this top level?  Because often
350          * there will be no work to do at all, and we'd prefer not to
351          * go all the way down to the bottom just to discover that.
352          *
353          * Why all these "- 1"s?  Because 0 represents both the bottom
354          * of the address space and the top of it (using -1 for the
355          * top wouldn't help much: the masks would do the wrong thing).
356          * The rule is that addr 0 and floor 0 refer to the bottom of
357          * the address space, but end 0 and ceiling 0 refer to the top
358          * Comparisons need to use "end - 1" and "ceiling - 1" (though
359          * that end 0 case should be mythical).
360          *
361          * Wherever addr is brought up or ceiling brought down, we must
362          * be careful to reject "the opposite 0" before it confuses the
363          * subsequent tests.  But what about where end is brought down
364          * by PMD_SIZE below? no, end can't go down to 0 there.
365          *
366          * Whereas we round start (addr) and ceiling down, by different
367          * masks at different levels, in order to test whether a table
368          * now has no other vmas using it, so can be freed, we don't
369          * bother to round floor or end up - the tests don't need that.
370          */
371
372         addr &= PMD_MASK;
373         if (addr < floor) {
374                 addr += PMD_SIZE;
375                 if (!addr)
376                         return;
377         }
378         if (ceiling) {
379                 ceiling &= PMD_MASK;
380                 if (!ceiling)
381                         return;
382         }
383         if (end - 1 > ceiling - 1)
384                 end -= PMD_SIZE;
385         if (addr > end - 1)
386                 return;
387         /*
388          * We add page table cache pages with PAGE_SIZE,
389          * (see pte_free_tlb()), flush the tlb if we need
390          */
391         tlb_change_page_size(tlb, PAGE_SIZE);
392         pgd = pgd_offset(tlb->mm, addr);
393         do {
394                 next = pgd_addr_end(addr, end);
395                 if (pgd_none_or_clear_bad(pgd))
396                         continue;
397                 free_p4d_range(tlb, pgd, addr, next, floor, ceiling);
398         } while (pgd++, addr = next, addr != end);
399 }
400
401 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
402                 unsigned long floor, unsigned long ceiling)
403 {
404         while (vma) {
405                 struct vm_area_struct *next = vma->vm_next;
406                 unsigned long addr = vma->vm_start;
407
408                 /*
409                  * Hide vma from rmap and truncate_pagecache before freeing
410                  * pgtables
411                  */
412                 unlink_anon_vmas(vma);
413                 unlink_file_vma(vma);
414
415                 if (is_vm_hugetlb_page(vma)) {
416                         hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
417                                 floor, next ? next->vm_start : ceiling);
418                 } else {
419                         /*
420                          * Optimization: gather nearby vmas into one call down
421                          */
422                         while (next && next->vm_start <= vma->vm_end + PMD_SIZE
423                                && !is_vm_hugetlb_page(next)) {
424                                 vma = next;
425                                 next = vma->vm_next;
426                                 unlink_anon_vmas(vma);
427                                 unlink_file_vma(vma);
428                         }
429                         free_pgd_range(tlb, addr, vma->vm_end,
430                                 floor, next ? next->vm_start : ceiling);
431                 }
432                 vma = next;
433         }
434 }
435
436 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd)
437 {
438         spinlock_t *ptl;
439         pgtable_t new = pte_alloc_one(mm);
440         if (!new)
441                 return -ENOMEM;
442
443         /*
444          * Ensure all pte setup (eg. pte page lock and page clearing) are
445          * visible before the pte is made visible to other CPUs by being
446          * put into page tables.
447          *
448          * The other side of the story is the pointer chasing in the page
449          * table walking code (when walking the page table without locking;
450          * ie. most of the time). Fortunately, these data accesses consist
451          * of a chain of data-dependent loads, meaning most CPUs (alpha
452          * being the notable exception) will already guarantee loads are
453          * seen in-order. See the alpha page table accessors for the
454          * smp_rmb() barriers in page table walking code.
455          */
456         smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
457
458         ptl = pmd_lock(mm, pmd);
459         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
460                 mm_inc_nr_ptes(mm);
461                 pmd_populate(mm, pmd, new);
462                 new = NULL;
463         }
464         spin_unlock(ptl);
465         if (new)
466                 pte_free(mm, new);
467         return 0;
468 }
469
470 int __pte_alloc_kernel(pmd_t *pmd)
471 {
472         pte_t *new = pte_alloc_one_kernel(&init_mm);
473         if (!new)
474                 return -ENOMEM;
475
476         smp_wmb(); /* See comment in __pte_alloc */
477
478         spin_lock(&init_mm.page_table_lock);
479         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
480                 pmd_populate_kernel(&init_mm, pmd, new);
481                 new = NULL;
482         }
483         spin_unlock(&init_mm.page_table_lock);
484         if (new)
485                 pte_free_kernel(&init_mm, new);
486         return 0;
487 }
488
489 static inline void init_rss_vec(int *rss)
490 {
491         memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
492 }
493
494 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
495 {
496         int i;
497
498         if (current->mm == mm)
499                 sync_mm_rss(mm);
500         for (i = 0; i < NR_MM_COUNTERS; i++)
501                 if (rss[i])
502                         add_mm_counter(mm, i, rss[i]);
503 }
504
505 /*
506  * This function is called to print an error when a bad pte
507  * is found. For example, we might have a PFN-mapped pte in
508  * a region that doesn't allow it.
509  *
510  * The calling function must still handle the error.
511  */
512 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
513                           pte_t pte, struct page *page)
514 {
515         pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
516         p4d_t *p4d = p4d_offset(pgd, addr);
517         pud_t *pud = pud_offset(p4d, addr);
518         pmd_t *pmd = pmd_offset(pud, addr);
519         struct address_space *mapping;
520         pgoff_t index;
521         static unsigned long resume;
522         static unsigned long nr_shown;
523         static unsigned long nr_unshown;
524
525         /*
526          * Allow a burst of 60 reports, then keep quiet for that minute;
527          * or allow a steady drip of one report per second.
528          */
529         if (nr_shown == 60) {
530                 if (time_before(jiffies, resume)) {
531                         nr_unshown++;
532                         return;
533                 }
534                 if (nr_unshown) {
535                         pr_alert("BUG: Bad page map: %lu messages suppressed\n",
536                                  nr_unshown);
537                         nr_unshown = 0;
538                 }
539                 nr_shown = 0;
540         }
541         if (nr_shown++ == 0)
542                 resume = jiffies + 60 * HZ;
543
544         mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
545         index = linear_page_index(vma, addr);
546
547         pr_alert("BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
548                  current->comm,
549                  (long long)pte_val(pte), (long long)pmd_val(*pmd));
550         if (page)
551                 dump_page(page, "bad pte");
552         pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n",
553                  (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
554         pr_alert("file:%pD fault:%ps mmap:%ps readpage:%ps\n",
555                  vma->vm_file,
556                  vma->vm_ops ? vma->vm_ops->fault : NULL,
557                  vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
558                  mapping ? mapping->a_ops->readpage : NULL);
559         dump_stack();
560         add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
561 }
562
563 /*
564  * vm_normal_page -- This function gets the "struct page" associated with a pte.
565  *
566  * "Special" mappings do not wish to be associated with a "struct page" (either
567  * it doesn't exist, or it exists but they don't want to touch it). In this
568  * case, NULL is returned here. "Normal" mappings do have a struct page.
569  *
570  * There are 2 broad cases. Firstly, an architecture may define a pte_special()
571  * pte bit, in which case this function is trivial. Secondly, an architecture
572  * may not have a spare pte bit, which requires a more complicated scheme,
573  * described below.
574  *
575  * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
576  * special mapping (even if there are underlying and valid "struct pages").
577  * COWed pages of a VM_PFNMAP are always normal.
578  *
579  * The way we recognize COWed pages within VM_PFNMAP mappings is through the
580  * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
581  * set, and the vm_pgoff will point to the first PFN mapped: thus every special
582  * mapping will always honor the rule
583  *
584  *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
585  *
586  * And for normal mappings this is false.
587  *
588  * This restricts such mappings to be a linear translation from virtual address
589  * to pfn. To get around this restriction, we allow arbitrary mappings so long
590  * as the vma is not a COW mapping; in that case, we know that all ptes are
591  * special (because none can have been COWed).
592  *
593  *
594  * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
595  *
596  * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
597  * page" backing, however the difference is that _all_ pages with a struct
598  * page (that is, those where pfn_valid is true) are refcounted and considered
599  * normal pages by the VM. The disadvantage is that pages are refcounted
600  * (which can be slower and simply not an option for some PFNMAP users). The
601  * advantage is that we don't have to follow the strict linearity rule of
602  * PFNMAP mappings in order to support COWable mappings.
603  *
604  */
605 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
606                             pte_t pte)
607 {
608         unsigned long pfn = pte_pfn(pte);
609
610         if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) {
611                 if (likely(!pte_special(pte)))
612                         goto check_pfn;
613                 if (vma->vm_ops && vma->vm_ops->find_special_page)
614                         return vma->vm_ops->find_special_page(vma, addr);
615                 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
616                         return NULL;
617                 if (is_zero_pfn(pfn))
618                         return NULL;
619                 if (pte_devmap(pte))
620                         return NULL;
621
622                 print_bad_pte(vma, addr, pte, NULL);
623                 return NULL;
624         }
625
626         /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */
627
628         if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
629                 if (vma->vm_flags & VM_MIXEDMAP) {
630                         if (!pfn_valid(pfn))
631                                 return NULL;
632                         goto out;
633                 } else {
634                         unsigned long off;
635                         off = (addr - vma->vm_start) >> PAGE_SHIFT;
636                         if (pfn == vma->vm_pgoff + off)
637                                 return NULL;
638                         if (!is_cow_mapping(vma->vm_flags))
639                                 return NULL;
640                 }
641         }
642
643         if (is_zero_pfn(pfn))
644                 return NULL;
645
646 check_pfn:
647         if (unlikely(pfn > highest_memmap_pfn)) {
648                 print_bad_pte(vma, addr, pte, NULL);
649                 return NULL;
650         }
651
652         /*
653          * NOTE! We still have PageReserved() pages in the page tables.
654          * eg. VDSO mappings can cause them to exist.
655          */
656 out:
657         return pfn_to_page(pfn);
658 }
659
660 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
661 struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
662                                 pmd_t pmd)
663 {
664         unsigned long pfn = pmd_pfn(pmd);
665
666         /*
667          * There is no pmd_special() but there may be special pmds, e.g.
668          * in a direct-access (dax) mapping, so let's just replicate the
669          * !CONFIG_ARCH_HAS_PTE_SPECIAL case from vm_normal_page() here.
670          */
671         if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
672                 if (vma->vm_flags & VM_MIXEDMAP) {
673                         if (!pfn_valid(pfn))
674                                 return NULL;
675                         goto out;
676                 } else {
677                         unsigned long off;
678                         off = (addr - vma->vm_start) >> PAGE_SHIFT;
679                         if (pfn == vma->vm_pgoff + off)
680                                 return NULL;
681                         if (!is_cow_mapping(vma->vm_flags))
682                                 return NULL;
683                 }
684         }
685
686         if (pmd_devmap(pmd))
687                 return NULL;
688         if (is_huge_zero_pmd(pmd))
689                 return NULL;
690         if (unlikely(pfn > highest_memmap_pfn))
691                 return NULL;
692
693         /*
694          * NOTE! We still have PageReserved() pages in the page tables.
695          * eg. VDSO mappings can cause them to exist.
696          */
697 out:
698         return pfn_to_page(pfn);
699 }
700 #endif
701
702 static void restore_exclusive_pte(struct vm_area_struct *vma,
703                                   struct page *page, unsigned long address,
704                                   pte_t *ptep)
705 {
706         pte_t pte;
707         swp_entry_t entry;
708
709         pte = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot)));
710         if (pte_swp_soft_dirty(*ptep))
711                 pte = pte_mksoft_dirty(pte);
712
713         entry = pte_to_swp_entry(*ptep);
714         if (pte_swp_uffd_wp(*ptep))
715                 pte = pte_mkuffd_wp(pte);
716         else if (is_writable_device_exclusive_entry(entry))
717                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
718
719         set_pte_at(vma->vm_mm, address, ptep, pte);
720
721         /*
722          * No need to take a page reference as one was already
723          * created when the swap entry was made.
724          */
725         if (PageAnon(page))
726                 page_add_anon_rmap(page, vma, address, false);
727         else
728                 /*
729                  * Currently device exclusive access only supports anonymous
730                  * memory so the entry shouldn't point to a filebacked page.
731                  */
732                 WARN_ON_ONCE(!PageAnon(page));
733
734         if (vma->vm_flags & VM_LOCKED)
735                 mlock_vma_page(page);
736
737         /*
738          * No need to invalidate - it was non-present before. However
739          * secondary CPUs may have mappings that need invalidating.
740          */
741         update_mmu_cache(vma, address, ptep);
742 }
743
744 /*
745  * Tries to restore an exclusive pte if the page lock can be acquired without
746  * sleeping.
747  */
748 static int
749 try_restore_exclusive_pte(pte_t *src_pte, struct vm_area_struct *vma,
750                         unsigned long addr)
751 {
752         swp_entry_t entry = pte_to_swp_entry(*src_pte);
753         struct page *page = pfn_swap_entry_to_page(entry);
754
755         if (trylock_page(page)) {
756                 restore_exclusive_pte(vma, page, addr, src_pte);
757                 unlock_page(page);
758                 return 0;
759         }
760
761         return -EBUSY;
762 }
763
764 /*
765  * copy one vm_area from one task to the other. Assumes the page tables
766  * already present in the new task to be cleared in the whole range
767  * covered by this vma.
768  */
769
770 static unsigned long
771 copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
772                 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *dst_vma,
773                 struct vm_area_struct *src_vma, unsigned long addr, int *rss)
774 {
775         unsigned long vm_flags = dst_vma->vm_flags;
776         pte_t pte = *src_pte;
777         struct page *page;
778         swp_entry_t entry = pte_to_swp_entry(pte);
779
780         if (likely(!non_swap_entry(entry))) {
781                 if (swap_duplicate(entry) < 0)
782                         return -EIO;
783
784                 /* make sure dst_mm is on swapoff's mmlist. */
785                 if (unlikely(list_empty(&dst_mm->mmlist))) {
786                         spin_lock(&mmlist_lock);
787                         if (list_empty(&dst_mm->mmlist))
788                                 list_add(&dst_mm->mmlist,
789                                                 &src_mm->mmlist);
790                         spin_unlock(&mmlist_lock);
791                 }
792                 rss[MM_SWAPENTS]++;
793         } else if (is_migration_entry(entry)) {
794                 page = pfn_swap_entry_to_page(entry);
795
796                 rss[mm_counter(page)]++;
797
798                 if (is_writable_migration_entry(entry) &&
799                                 is_cow_mapping(vm_flags)) {
800                         /*
801                          * COW mappings require pages in both
802                          * parent and child to be set to read.
803                          */
804                         entry = make_readable_migration_entry(
805                                                         swp_offset(entry));
806                         pte = swp_entry_to_pte(entry);
807                         if (pte_swp_soft_dirty(*src_pte))
808                                 pte = pte_swp_mksoft_dirty(pte);
809                         if (pte_swp_uffd_wp(*src_pte))
810                                 pte = pte_swp_mkuffd_wp(pte);
811                         set_pte_at(src_mm, addr, src_pte, pte);
812                 }
813         } else if (is_device_private_entry(entry)) {
814                 page = pfn_swap_entry_to_page(entry);
815
816                 /*
817                  * Update rss count even for unaddressable pages, as
818                  * they should treated just like normal pages in this
819                  * respect.
820                  *
821                  * We will likely want to have some new rss counters
822                  * for unaddressable pages, at some point. But for now
823                  * keep things as they are.
824                  */
825                 get_page(page);
826                 rss[mm_counter(page)]++;
827                 page_dup_rmap(page, false);
828
829                 /*
830                  * We do not preserve soft-dirty information, because so
831                  * far, checkpoint/restore is the only feature that
832                  * requires that. And checkpoint/restore does not work
833                  * when a device driver is involved (you cannot easily
834                  * save and restore device driver state).
835                  */
836                 if (is_writable_device_private_entry(entry) &&
837                     is_cow_mapping(vm_flags)) {
838                         entry = make_readable_device_private_entry(
839                                                         swp_offset(entry));
840                         pte = swp_entry_to_pte(entry);
841                         if (pte_swp_uffd_wp(*src_pte))
842                                 pte = pte_swp_mkuffd_wp(pte);
843                         set_pte_at(src_mm, addr, src_pte, pte);
844                 }
845         } else if (is_device_exclusive_entry(entry)) {
846                 /*
847                  * Make device exclusive entries present by restoring the
848                  * original entry then copying as for a present pte. Device
849                  * exclusive entries currently only support private writable
850                  * (ie. COW) mappings.
851                  */
852                 VM_BUG_ON(!is_cow_mapping(src_vma->vm_flags));
853                 if (try_restore_exclusive_pte(src_pte, src_vma, addr))
854                         return -EBUSY;
855                 return -ENOENT;
856         }
857         if (!userfaultfd_wp(dst_vma))
858                 pte = pte_swp_clear_uffd_wp(pte);
859         set_pte_at(dst_mm, addr, dst_pte, pte);
860         return 0;
861 }
862
863 /*
864  * Copy a present and normal page if necessary.
865  *
866  * NOTE! The usual case is that this doesn't need to do
867  * anything, and can just return a positive value. That
868  * will let the caller know that it can just increase
869  * the page refcount and re-use the pte the traditional
870  * way.
871  *
872  * But _if_ we need to copy it because it needs to be
873  * pinned in the parent (and the child should get its own
874  * copy rather than just a reference to the same page),
875  * we'll do that here and return zero to let the caller
876  * know we're done.
877  *
878  * And if we need a pre-allocated page but don't yet have
879  * one, return a negative error to let the preallocation
880  * code know so that it can do so outside the page table
881  * lock.
882  */
883 static inline int
884 copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
885                   pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss,
886                   struct page **prealloc, pte_t pte, struct page *page)
887 {
888         struct page *new_page;
889
890         /*
891          * What we want to do is to check whether this page may
892          * have been pinned by the parent process.  If so,
893          * instead of wrprotect the pte on both sides, we copy
894          * the page immediately so that we'll always guarantee
895          * the pinned page won't be randomly replaced in the
896          * future.
897          *
898          * The page pinning checks are just "has this mm ever
899          * seen pinning", along with the (inexact) check of
900          * the page count. That might give false positives for
901          * for pinning, but it will work correctly.
902          */
903         if (likely(!page_needs_cow_for_dma(src_vma, page)))
904                 return 1;
905
906         new_page = *prealloc;
907         if (!new_page)
908                 return -EAGAIN;
909
910         /*
911          * We have a prealloc page, all good!  Take it
912          * over and copy the page & arm it.
913          */
914         *prealloc = NULL;
915         copy_user_highpage(new_page, page, addr, src_vma);
916         __SetPageUptodate(new_page);
917         page_add_new_anon_rmap(new_page, dst_vma, addr, false);
918         lru_cache_add_inactive_or_unevictable(new_page, dst_vma);
919         rss[mm_counter(new_page)]++;
920
921         /* All done, just insert the new page copy in the child */
922         pte = mk_pte(new_page, dst_vma->vm_page_prot);
923         pte = maybe_mkwrite(pte_mkdirty(pte), dst_vma);
924         if (userfaultfd_pte_wp(dst_vma, *src_pte))
925                 /* Uffd-wp needs to be delivered to dest pte as well */
926                 pte = pte_wrprotect(pte_mkuffd_wp(pte));
927         set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);
928         return 0;
929 }
930
931 /*
932  * Copy one pte.  Returns 0 if succeeded, or -EAGAIN if one preallocated page
933  * is required to copy this pte.
934  */
935 static inline int
936 copy_present_pte(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
937                  pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss,
938                  struct page **prealloc)
939 {
940         struct mm_struct *src_mm = src_vma->vm_mm;
941         unsigned long vm_flags = src_vma->vm_flags;
942         pte_t pte = *src_pte;
943         struct page *page;
944
945         page = vm_normal_page(src_vma, addr, pte);
946         if (page) {
947                 int retval;
948
949                 retval = copy_present_page(dst_vma, src_vma, dst_pte, src_pte,
950                                            addr, rss, prealloc, pte, page);
951                 if (retval <= 0)
952                         return retval;
953
954                 get_page(page);
955                 page_dup_rmap(page, false);
956                 rss[mm_counter(page)]++;
957         }
958
959         /*
960          * If it's a COW mapping, write protect it both
961          * in the parent and the child
962          */
963         if (is_cow_mapping(vm_flags) && pte_write(pte)) {
964                 ptep_set_wrprotect(src_mm, addr, src_pte);
965                 pte = pte_wrprotect(pte);
966         }
967
968         /*
969          * If it's a shared mapping, mark it clean in
970          * the child
971          */
972         if (vm_flags & VM_SHARED)
973                 pte = pte_mkclean(pte);
974         pte = pte_mkold(pte);
975
976         if (!userfaultfd_wp(dst_vma))
977                 pte = pte_clear_uffd_wp(pte);
978
979         set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);
980         return 0;
981 }
982
983 static inline struct page *
984 page_copy_prealloc(struct mm_struct *src_mm, struct vm_area_struct *vma,
985                    unsigned long addr)
986 {
987         struct page *new_page;
988
989         new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, addr);
990         if (!new_page)
991                 return NULL;
992
993         if (mem_cgroup_charge(new_page, src_mm, GFP_KERNEL)) {
994                 put_page(new_page);
995                 return NULL;
996         }
997         cgroup_throttle_swaprate(new_page, GFP_KERNEL);
998
999         return new_page;
1000 }
1001
1002 static int
1003 copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1004                pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
1005                unsigned long end)
1006 {
1007         struct mm_struct *dst_mm = dst_vma->vm_mm;
1008         struct mm_struct *src_mm = src_vma->vm_mm;
1009         pte_t *orig_src_pte, *orig_dst_pte;
1010         pte_t *src_pte, *dst_pte;
1011         spinlock_t *src_ptl, *dst_ptl;
1012         int progress, ret = 0;
1013         int rss[NR_MM_COUNTERS];
1014         swp_entry_t entry = (swp_entry_t){0};
1015         struct page *prealloc = NULL;
1016
1017 again:
1018         progress = 0;
1019         init_rss_vec(rss);
1020
1021         dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
1022         if (!dst_pte) {
1023                 ret = -ENOMEM;
1024                 goto out;
1025         }
1026         src_pte = pte_offset_map(src_pmd, addr);
1027         src_ptl = pte_lockptr(src_mm, src_pmd);
1028         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1029         orig_src_pte = src_pte;
1030         orig_dst_pte = dst_pte;
1031         arch_enter_lazy_mmu_mode();
1032
1033         do {
1034                 /*
1035                  * We are holding two locks at this point - either of them
1036                  * could generate latencies in another task on another CPU.
1037                  */
1038                 if (progress >= 32) {
1039                         progress = 0;
1040                         if (need_resched() ||
1041                             spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
1042                                 break;
1043                 }
1044                 if (pte_none(*src_pte)) {
1045                         progress++;
1046                         continue;
1047                 }
1048                 if (unlikely(!pte_present(*src_pte))) {
1049                         ret = copy_nonpresent_pte(dst_mm, src_mm,
1050                                                   dst_pte, src_pte,
1051                                                   dst_vma, src_vma,
1052                                                   addr, rss);
1053                         if (ret == -EIO) {
1054                                 entry = pte_to_swp_entry(*src_pte);
1055                                 break;
1056                         } else if (ret == -EBUSY) {
1057                                 break;
1058                         } else if (!ret) {
1059                                 progress += 8;
1060                                 continue;
1061                         }
1062
1063                         /*
1064                          * Device exclusive entry restored, continue by copying
1065                          * the now present pte.
1066                          */
1067                         WARN_ON_ONCE(ret != -ENOENT);
1068                 }
1069                 /* copy_present_pte() will clear `*prealloc' if consumed */
1070                 ret = copy_present_pte(dst_vma, src_vma, dst_pte, src_pte,
1071                                        addr, rss, &prealloc);
1072                 /*
1073                  * If we need a pre-allocated page for this pte, drop the
1074                  * locks, allocate, and try again.
1075                  */
1076                 if (unlikely(ret == -EAGAIN))
1077                         break;
1078                 if (unlikely(prealloc)) {
1079                         /*
1080                          * pre-alloc page cannot be reused by next time so as
1081                          * to strictly follow mempolicy (e.g., alloc_page_vma()
1082                          * will allocate page according to address).  This
1083                          * could only happen if one pinned pte changed.
1084                          */
1085                         put_page(prealloc);
1086                         prealloc = NULL;
1087                 }
1088                 progress += 8;
1089         } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
1090
1091         arch_leave_lazy_mmu_mode();
1092         spin_unlock(src_ptl);
1093         pte_unmap(orig_src_pte);
1094         add_mm_rss_vec(dst_mm, rss);
1095         pte_unmap_unlock(orig_dst_pte, dst_ptl);
1096         cond_resched();
1097
1098         if (ret == -EIO) {
1099                 VM_WARN_ON_ONCE(!entry.val);
1100                 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) {
1101                         ret = -ENOMEM;
1102                         goto out;
1103                 }
1104                 entry.val = 0;
1105         } else if (ret == -EBUSY) {
1106                 goto out;
1107         } else if (ret ==  -EAGAIN) {
1108                 prealloc = page_copy_prealloc(src_mm, src_vma, addr);
1109                 if (!prealloc)
1110                         return -ENOMEM;
1111         } else if (ret) {
1112                 VM_WARN_ON_ONCE(1);
1113         }
1114
1115         /* We've captured and resolved the error. Reset, try again. */
1116         ret = 0;
1117
1118         if (addr != end)
1119                 goto again;
1120 out:
1121         if (unlikely(prealloc))
1122                 put_page(prealloc);
1123         return ret;
1124 }
1125
1126 static inline int
1127 copy_pmd_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1128                pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1129                unsigned long end)
1130 {
1131         struct mm_struct *dst_mm = dst_vma->vm_mm;
1132         struct mm_struct *src_mm = src_vma->vm_mm;
1133         pmd_t *src_pmd, *dst_pmd;
1134         unsigned long next;
1135
1136         dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
1137         if (!dst_pmd)
1138                 return -ENOMEM;
1139         src_pmd = pmd_offset(src_pud, addr);
1140         do {
1141                 next = pmd_addr_end(addr, end);
1142                 if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
1143                         || pmd_devmap(*src_pmd)) {
1144                         int err;
1145                         VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, src_vma);
1146                         err = copy_huge_pmd(dst_mm, src_mm, dst_pmd, src_pmd,
1147                                             addr, dst_vma, src_vma);
1148                         if (err == -ENOMEM)
1149                                 return -ENOMEM;
1150                         if (!err)
1151                                 continue;
1152                         /* fall through */
1153                 }
1154                 if (pmd_none_or_clear_bad(src_pmd))
1155                         continue;
1156                 if (copy_pte_range(dst_vma, src_vma, dst_pmd, src_pmd,
1157                                    addr, next))
1158                         return -ENOMEM;
1159         } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1160         return 0;
1161 }
1162
1163 static inline int
1164 copy_pud_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1165                p4d_t *dst_p4d, p4d_t *src_p4d, unsigned long addr,
1166                unsigned long end)
1167 {
1168         struct mm_struct *dst_mm = dst_vma->vm_mm;
1169         struct mm_struct *src_mm = src_vma->vm_mm;
1170         pud_t *src_pud, *dst_pud;
1171         unsigned long next;
1172
1173         dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
1174         if (!dst_pud)
1175                 return -ENOMEM;
1176         src_pud = pud_offset(src_p4d, addr);
1177         do {
1178                 next = pud_addr_end(addr, end);
1179                 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
1180                         int err;
1181
1182                         VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, src_vma);
1183                         err = copy_huge_pud(dst_mm, src_mm,
1184                                             dst_pud, src_pud, addr, src_vma);
1185                         if (err == -ENOMEM)
1186                                 return -ENOMEM;
1187                         if (!err)
1188                                 continue;
1189                         /* fall through */
1190                 }
1191                 if (pud_none_or_clear_bad(src_pud))
1192                         continue;
1193                 if (copy_pmd_range(dst_vma, src_vma, dst_pud, src_pud,
1194                                    addr, next))
1195                         return -ENOMEM;
1196         } while (dst_pud++, src_pud++, addr = next, addr != end);
1197         return 0;
1198 }
1199
1200 static inline int
1201 copy_p4d_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1202                pgd_t *dst_pgd, pgd_t *src_pgd, unsigned long addr,
1203                unsigned long end)
1204 {
1205         struct mm_struct *dst_mm = dst_vma->vm_mm;
1206         p4d_t *src_p4d, *dst_p4d;
1207         unsigned long next;
1208
1209         dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
1210         if (!dst_p4d)
1211                 return -ENOMEM;
1212         src_p4d = p4d_offset(src_pgd, addr);
1213         do {
1214                 next = p4d_addr_end(addr, end);
1215                 if (p4d_none_or_clear_bad(src_p4d))
1216                         continue;
1217                 if (copy_pud_range(dst_vma, src_vma, dst_p4d, src_p4d,
1218                                    addr, next))
1219                         return -ENOMEM;
1220         } while (dst_p4d++, src_p4d++, addr = next, addr != end);
1221         return 0;
1222 }
1223
1224 int
1225 copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
1226 {
1227         pgd_t *src_pgd, *dst_pgd;
1228         unsigned long next;
1229         unsigned long addr = src_vma->vm_start;
1230         unsigned long end = src_vma->vm_end;
1231         struct mm_struct *dst_mm = dst_vma->vm_mm;
1232         struct mm_struct *src_mm = src_vma->vm_mm;
1233         struct mmu_notifier_range range;
1234         bool is_cow;
1235         int ret;
1236
1237         /*
1238          * Don't copy ptes where a page fault will fill them correctly.
1239          * Fork becomes much lighter when there are big shared or private
1240          * readonly mappings. The tradeoff is that copy_page_range is more
1241          * efficient than faulting.
1242          */
1243         if (!(src_vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
1244             !src_vma->anon_vma)
1245                 return 0;
1246
1247         if (is_vm_hugetlb_page(src_vma))
1248                 return copy_hugetlb_page_range(dst_mm, src_mm, src_vma);
1249
1250         if (unlikely(src_vma->vm_flags & VM_PFNMAP)) {
1251                 /*
1252                  * We do not free on error cases below as remove_vma
1253                  * gets called on error from higher level routine
1254                  */
1255                 ret = track_pfn_copy(src_vma);
1256                 if (ret)
1257                         return ret;
1258         }
1259
1260         /*
1261          * We need to invalidate the secondary MMU mappings only when
1262          * there could be a permission downgrade on the ptes of the
1263          * parent mm. And a permission downgrade will only happen if
1264          * is_cow_mapping() returns true.
1265          */
1266         is_cow = is_cow_mapping(src_vma->vm_flags);
1267
1268         if (is_cow) {
1269                 mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE,
1270                                         0, src_vma, src_mm, addr, end);
1271                 mmu_notifier_invalidate_range_start(&range);
1272                 /*
1273                  * Disabling preemption is not needed for the write side, as
1274                  * the read side doesn't spin, but goes to the mmap_lock.
1275                  *
1276                  * Use the raw variant of the seqcount_t write API to avoid
1277                  * lockdep complaining about preemptibility.
1278                  */
1279                 mmap_assert_write_locked(src_mm);
1280                 raw_write_seqcount_begin(&src_mm->write_protect_seq);
1281         }
1282
1283         ret = 0;
1284         dst_pgd = pgd_offset(dst_mm, addr);
1285         src_pgd = pgd_offset(src_mm, addr);
1286         do {
1287                 next = pgd_addr_end(addr, end);
1288                 if (pgd_none_or_clear_bad(src_pgd))
1289                         continue;
1290                 if (unlikely(copy_p4d_range(dst_vma, src_vma, dst_pgd, src_pgd,
1291                                             addr, next))) {
1292                         ret = -ENOMEM;
1293                         break;
1294                 }
1295         } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1296
1297         if (is_cow) {
1298                 raw_write_seqcount_end(&src_mm->write_protect_seq);
1299                 mmu_notifier_invalidate_range_end(&range);
1300         }
1301         return ret;
1302 }
1303
1304 static unsigned long zap_pte_range(struct mmu_gather *tlb,
1305                                 struct vm_area_struct *vma, pmd_t *pmd,
1306                                 unsigned long addr, unsigned long end,
1307                                 struct zap_details *details)
1308 {
1309         struct mm_struct *mm = tlb->mm;
1310         int force_flush = 0;
1311         int rss[NR_MM_COUNTERS];
1312         spinlock_t *ptl;
1313         pte_t *start_pte;
1314         pte_t *pte;
1315         swp_entry_t entry;
1316
1317         tlb_change_page_size(tlb, PAGE_SIZE);
1318 again:
1319         init_rss_vec(rss);
1320         start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1321         pte = start_pte;
1322         flush_tlb_batched_pending(mm);
1323         arch_enter_lazy_mmu_mode();
1324         do {
1325                 pte_t ptent = *pte;
1326                 if (pte_none(ptent))
1327                         continue;
1328
1329                 if (need_resched())
1330                         break;
1331
1332                 if (pte_present(ptent)) {
1333                         struct page *page;
1334
1335                         page = vm_normal_page(vma, addr, ptent);
1336                         if (unlikely(details) && page) {
1337                                 /*
1338                                  * unmap_shared_mapping_pages() wants to
1339                                  * invalidate cache without truncating:
1340                                  * unmap shared but keep private pages.
1341                                  */
1342                                 if (details->check_mapping &&
1343                                     details->check_mapping != page_rmapping(page))
1344                                         continue;
1345                         }
1346                         ptent = ptep_get_and_clear_full(mm, addr, pte,
1347                                                         tlb->fullmm);
1348                         tlb_remove_tlb_entry(tlb, pte, addr);
1349                         if (unlikely(!page))
1350                                 continue;
1351
1352                         if (!PageAnon(page)) {
1353                                 if (pte_dirty(ptent)) {
1354                                         force_flush = 1;
1355                                         set_page_dirty(page);
1356                                 }
1357                                 if (pte_young(ptent) &&
1358                                     likely(!(vma->vm_flags & VM_SEQ_READ)))
1359                                         mark_page_accessed(page);
1360                         }
1361                         rss[mm_counter(page)]--;
1362                         page_remove_rmap(page, false);
1363                         if (unlikely(page_mapcount(page) < 0))
1364                                 print_bad_pte(vma, addr, ptent, page);
1365                         if (unlikely(__tlb_remove_page(tlb, page))) {
1366                                 force_flush = 1;
1367                                 addr += PAGE_SIZE;
1368                                 break;
1369                         }
1370                         continue;
1371                 }
1372
1373                 entry = pte_to_swp_entry(ptent);
1374                 if (is_device_private_entry(entry) ||
1375                     is_device_exclusive_entry(entry)) {
1376                         struct page *page = pfn_swap_entry_to_page(entry);
1377
1378                         if (unlikely(details && details->check_mapping)) {
1379                                 /*
1380                                  * unmap_shared_mapping_pages() wants to
1381                                  * invalidate cache without truncating:
1382                                  * unmap shared but keep private pages.
1383                                  */
1384                                 if (details->check_mapping !=
1385                                     page_rmapping(page))
1386                                         continue;
1387                         }
1388
1389                         pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1390                         rss[mm_counter(page)]--;
1391
1392                         if (is_device_private_entry(entry))
1393                                 page_remove_rmap(page, false);
1394
1395                         put_page(page);
1396                         continue;
1397                 }
1398
1399                 /* If details->check_mapping, we leave swap entries. */
1400                 if (unlikely(details))
1401                         continue;
1402
1403                 if (!non_swap_entry(entry))
1404                         rss[MM_SWAPENTS]--;
1405                 else if (is_migration_entry(entry)) {
1406                         struct page *page;
1407
1408                         page = pfn_swap_entry_to_page(entry);
1409                         rss[mm_counter(page)]--;
1410                 }
1411                 if (unlikely(!free_swap_and_cache(entry)))
1412                         print_bad_pte(vma, addr, ptent, NULL);
1413                 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1414         } while (pte++, addr += PAGE_SIZE, addr != end);
1415
1416         add_mm_rss_vec(mm, rss);
1417         arch_leave_lazy_mmu_mode();
1418
1419         /* Do the actual TLB flush before dropping ptl */
1420         if (force_flush)
1421                 tlb_flush_mmu_tlbonly(tlb);
1422         pte_unmap_unlock(start_pte, ptl);
1423
1424         /*
1425          * If we forced a TLB flush (either due to running out of
1426          * batch buffers or because we needed to flush dirty TLB
1427          * entries before releasing the ptl), free the batched
1428          * memory too. Restart if we didn't do everything.
1429          */
1430         if (force_flush) {
1431                 force_flush = 0;
1432                 tlb_flush_mmu(tlb);
1433         }
1434
1435         if (addr != end) {
1436                 cond_resched();
1437                 goto again;
1438         }
1439
1440         return addr;
1441 }
1442
1443 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1444                                 struct vm_area_struct *vma, pud_t *pud,
1445                                 unsigned long addr, unsigned long end,
1446                                 struct zap_details *details)
1447 {
1448         pmd_t *pmd;
1449         unsigned long next;
1450
1451         pmd = pmd_offset(pud, addr);
1452         do {
1453                 next = pmd_addr_end(addr, end);
1454                 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1455                         if (next - addr != HPAGE_PMD_SIZE)
1456                                 __split_huge_pmd(vma, pmd, addr, false, NULL);
1457                         else if (zap_huge_pmd(tlb, vma, pmd, addr))
1458                                 goto next;
1459                         /* fall through */
1460                 } else if (details && details->single_page &&
1461                            PageTransCompound(details->single_page) &&
1462                            next - addr == HPAGE_PMD_SIZE && pmd_none(*pmd)) {
1463                         spinlock_t *ptl = pmd_lock(tlb->mm, pmd);
1464                         /*
1465                          * Take and drop THP pmd lock so that we cannot return
1466                          * prematurely, while zap_huge_pmd() has cleared *pmd,
1467                          * but not yet decremented compound_mapcount().
1468                          */
1469                         spin_unlock(ptl);
1470                 }
1471
1472                 /*
1473                  * Here there can be other concurrent MADV_DONTNEED or
1474                  * trans huge page faults running, and if the pmd is
1475                  * none or trans huge it can change under us. This is
1476                  * because MADV_DONTNEED holds the mmap_lock in read
1477                  * mode.
1478                  */
1479                 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1480                         goto next;
1481                 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1482 next:
1483                 cond_resched();
1484         } while (pmd++, addr = next, addr != end);
1485
1486         return addr;
1487 }
1488
1489 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1490                                 struct vm_area_struct *vma, p4d_t *p4d,
1491                                 unsigned long addr, unsigned long end,
1492                                 struct zap_details *details)
1493 {
1494         pud_t *pud;
1495         unsigned long next;
1496
1497         pud = pud_offset(p4d, addr);
1498         do {
1499                 next = pud_addr_end(addr, end);
1500                 if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1501                         if (next - addr != HPAGE_PUD_SIZE) {
1502                                 mmap_assert_locked(tlb->mm);
1503                                 split_huge_pud(vma, pud, addr);
1504                         } else if (zap_huge_pud(tlb, vma, pud, addr))
1505                                 goto next;
1506                         /* fall through */
1507                 }
1508                 if (pud_none_or_clear_bad(pud))
1509                         continue;
1510                 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1511 next:
1512                 cond_resched();
1513         } while (pud++, addr = next, addr != end);
1514
1515         return addr;
1516 }
1517
1518 static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
1519                                 struct vm_area_struct *vma, pgd_t *pgd,
1520                                 unsigned long addr, unsigned long end,
1521                                 struct zap_details *details)
1522 {
1523         p4d_t *p4d;
1524         unsigned long next;
1525
1526         p4d = p4d_offset(pgd, addr);
1527         do {
1528                 next = p4d_addr_end(addr, end);
1529                 if (p4d_none_or_clear_bad(p4d))
1530                         continue;
1531                 next = zap_pud_range(tlb, vma, p4d, addr, next, details);
1532         } while (p4d++, addr = next, addr != end);
1533
1534         return addr;
1535 }
1536
1537 void unmap_page_range(struct mmu_gather *tlb,
1538                              struct vm_area_struct *vma,
1539                              unsigned long addr, unsigned long end,
1540                              struct zap_details *details)
1541 {
1542         pgd_t *pgd;
1543         unsigned long next;
1544
1545         BUG_ON(addr >= end);
1546         tlb_start_vma(tlb, vma);
1547         pgd = pgd_offset(vma->vm_mm, addr);
1548         do {
1549                 next = pgd_addr_end(addr, end);
1550                 if (pgd_none_or_clear_bad(pgd))
1551                         continue;
1552                 next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
1553         } while (pgd++, addr = next, addr != end);
1554         tlb_end_vma(tlb, vma);
1555 }
1556
1557
1558 static void unmap_single_vma(struct mmu_gather *tlb,
1559                 struct vm_area_struct *vma, unsigned long start_addr,
1560                 unsigned long end_addr,
1561                 struct zap_details *details)
1562 {
1563         unsigned long start = max(vma->vm_start, start_addr);
1564         unsigned long end;
1565
1566         if (start >= vma->vm_end)
1567                 return;
1568         end = min(vma->vm_end, end_addr);
1569         if (end <= vma->vm_start)
1570                 return;
1571
1572         if (vma->vm_file)
1573                 uprobe_munmap(vma, start, end);
1574
1575         if (unlikely(vma->vm_flags & VM_PFNMAP))
1576                 untrack_pfn(vma, 0, 0);
1577
1578         if (start != end) {
1579                 if (unlikely(is_vm_hugetlb_page(vma))) {
1580                         /*
1581                          * It is undesirable to test vma->vm_file as it
1582                          * should be non-null for valid hugetlb area.
1583                          * However, vm_file will be NULL in the error
1584                          * cleanup path of mmap_region. When
1585                          * hugetlbfs ->mmap method fails,
1586                          * mmap_region() nullifies vma->vm_file
1587                          * before calling this function to clean up.
1588                          * Since no pte has actually been setup, it is
1589                          * safe to do nothing in this case.
1590                          */
1591                         if (vma->vm_file) {
1592                                 i_mmap_lock_write(vma->vm_file->f_mapping);
1593                                 __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1594                                 i_mmap_unlock_write(vma->vm_file->f_mapping);
1595                         }
1596                 } else
1597                         unmap_page_range(tlb, vma, start, end, details);
1598         }
1599 }
1600
1601 /**
1602  * unmap_vmas - unmap a range of memory covered by a list of vma's
1603  * @tlb: address of the caller's struct mmu_gather
1604  * @vma: the starting vma
1605  * @start_addr: virtual address at which to start unmapping
1606  * @end_addr: virtual address at which to end unmapping
1607  *
1608  * Unmap all pages in the vma list.
1609  *
1610  * Only addresses between `start' and `end' will be unmapped.
1611  *
1612  * The VMA list must be sorted in ascending virtual address order.
1613  *
1614  * unmap_vmas() assumes that the caller will flush the whole unmapped address
1615  * range after unmap_vmas() returns.  So the only responsibility here is to
1616  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1617  * drops the lock and schedules.
1618  */
1619 void unmap_vmas(struct mmu_gather *tlb,
1620                 struct vm_area_struct *vma, unsigned long start_addr,
1621                 unsigned long end_addr)
1622 {
1623         struct mmu_notifier_range range;
1624
1625         mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, vma->vm_mm,
1626                                 start_addr, end_addr);
1627         mmu_notifier_invalidate_range_start(&range);
1628         for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1629                 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1630         mmu_notifier_invalidate_range_end(&range);
1631 }
1632
1633 /**
1634  * zap_page_range - remove user pages in a given range
1635  * @vma: vm_area_struct holding the applicable pages
1636  * @start: starting address of pages to zap
1637  * @size: number of bytes to zap
1638  *
1639  * Caller must protect the VMA list
1640  */
1641 void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1642                 unsigned long size)
1643 {
1644         struct mmu_notifier_range range;
1645         struct mmu_gather tlb;
1646
1647         lru_add_drain();
1648         mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1649                                 start, start + size);
1650         tlb_gather_mmu(&tlb, vma->vm_mm);
1651         update_hiwater_rss(vma->vm_mm);
1652         mmu_notifier_invalidate_range_start(&range);
1653         for ( ; vma && vma->vm_start < range.end; vma = vma->vm_next)
1654                 unmap_single_vma(&tlb, vma, start, range.end, NULL);
1655         mmu_notifier_invalidate_range_end(&range);
1656         tlb_finish_mmu(&tlb);
1657 }
1658
1659 /**
1660  * zap_page_range_single - remove user pages in a given range
1661  * @vma: vm_area_struct holding the applicable pages
1662  * @address: starting address of pages to zap
1663  * @size: number of bytes to zap
1664  * @details: details of shared cache invalidation
1665  *
1666  * The range must fit into one VMA.
1667  */
1668 static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1669                 unsigned long size, struct zap_details *details)
1670 {
1671         struct mmu_notifier_range range;
1672         struct mmu_gather tlb;
1673
1674         lru_add_drain();
1675         mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1676                                 address, address + size);
1677         tlb_gather_mmu(&tlb, vma->vm_mm);
1678         update_hiwater_rss(vma->vm_mm);
1679         mmu_notifier_invalidate_range_start(&range);
1680         unmap_single_vma(&tlb, vma, address, range.end, details);
1681         mmu_notifier_invalidate_range_end(&range);
1682         tlb_finish_mmu(&tlb);
1683 }
1684
1685 /**
1686  * zap_vma_ptes - remove ptes mapping the vma
1687  * @vma: vm_area_struct holding ptes to be zapped
1688  * @address: starting address of pages to zap
1689  * @size: number of bytes to zap
1690  *
1691  * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1692  *
1693  * The entire address range must be fully contained within the vma.
1694  *
1695  */
1696 void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1697                 unsigned long size)
1698 {
1699         if (address < vma->vm_start || address + size > vma->vm_end ||
1700                         !(vma->vm_flags & VM_PFNMAP))
1701                 return;
1702
1703         zap_page_range_single(vma, address, size, NULL);
1704 }
1705 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1706
1707 static pmd_t *walk_to_pmd(struct mm_struct *mm, unsigned long addr)
1708 {
1709         pgd_t *pgd;
1710         p4d_t *p4d;
1711         pud_t *pud;
1712         pmd_t *pmd;
1713
1714         pgd = pgd_offset(mm, addr);
1715         p4d = p4d_alloc(mm, pgd, addr);
1716         if (!p4d)
1717                 return NULL;
1718         pud = pud_alloc(mm, p4d, addr);
1719         if (!pud)
1720                 return NULL;
1721         pmd = pmd_alloc(mm, pud, addr);
1722         if (!pmd)
1723                 return NULL;
1724
1725         VM_BUG_ON(pmd_trans_huge(*pmd));
1726         return pmd;
1727 }
1728
1729 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1730                         spinlock_t **ptl)
1731 {
1732         pmd_t *pmd = walk_to_pmd(mm, addr);
1733
1734         if (!pmd)
1735                 return NULL;
1736         return pte_alloc_map_lock(mm, pmd, addr, ptl);
1737 }
1738
1739 static int validate_page_before_insert(struct page *page)
1740 {
1741         if (PageAnon(page) || PageSlab(page) || page_has_type(page))
1742                 return -EINVAL;
1743         flush_dcache_page(page);
1744         return 0;
1745 }
1746
1747 static int insert_page_into_pte_locked(struct mm_struct *mm, pte_t *pte,
1748                         unsigned long addr, struct page *page, pgprot_t prot)
1749 {
1750         if (!pte_none(*pte))
1751                 return -EBUSY;
1752         /* Ok, finally just insert the thing.. */
1753         get_page(page);
1754         inc_mm_counter_fast(mm, mm_counter_file(page));
1755         page_add_file_rmap(page, false);
1756         set_pte_at(mm, addr, pte, mk_pte(page, prot));
1757         return 0;
1758 }
1759
1760 /*
1761  * This is the old fallback for page remapping.
1762  *
1763  * For historical reasons, it only allows reserved pages. Only
1764  * old drivers should use this, and they needed to mark their
1765  * pages reserved for the old functions anyway.
1766  */
1767 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1768                         struct page *page, pgprot_t prot)
1769 {
1770         struct mm_struct *mm = vma->vm_mm;
1771         int retval;
1772         pte_t *pte;
1773         spinlock_t *ptl;
1774
1775         retval = validate_page_before_insert(page);
1776         if (retval)
1777                 goto out;
1778         retval = -ENOMEM;
1779         pte = get_locked_pte(mm, addr, &ptl);
1780         if (!pte)
1781                 goto out;
1782         retval = insert_page_into_pte_locked(mm, pte, addr, page, prot);
1783         pte_unmap_unlock(pte, ptl);
1784 out:
1785         return retval;
1786 }
1787
1788 #ifdef pte_index
1789 static int insert_page_in_batch_locked(struct mm_struct *mm, pte_t *pte,
1790                         unsigned long addr, struct page *page, pgprot_t prot)
1791 {
1792         int err;
1793
1794         if (!page_count(page))
1795                 return -EINVAL;
1796         err = validate_page_before_insert(page);
1797         if (err)
1798                 return err;
1799         return insert_page_into_pte_locked(mm, pte, addr, page, prot);
1800 }
1801
1802 /* insert_pages() amortizes the cost of spinlock operations
1803  * when inserting pages in a loop. Arch *must* define pte_index.
1804  */
1805 static int insert_pages(struct vm_area_struct *vma, unsigned long addr,
1806                         struct page **pages, unsigned long *num, pgprot_t prot)
1807 {
1808         pmd_t *pmd = NULL;
1809         pte_t *start_pte, *pte;
1810         spinlock_t *pte_lock;
1811         struct mm_struct *const mm = vma->vm_mm;
1812         unsigned long curr_page_idx = 0;
1813         unsigned long remaining_pages_total = *num;
1814         unsigned long pages_to_write_in_pmd;
1815         int ret;
1816 more:
1817         ret = -EFAULT;
1818         pmd = walk_to_pmd(mm, addr);
1819         if (!pmd)
1820                 goto out;
1821
1822         pages_to_write_in_pmd = min_t(unsigned long,
1823                 remaining_pages_total, PTRS_PER_PTE - pte_index(addr));
1824
1825         /* Allocate the PTE if necessary; takes PMD lock once only. */
1826         ret = -ENOMEM;
1827         if (pte_alloc(mm, pmd))
1828                 goto out;
1829
1830         while (pages_to_write_in_pmd) {
1831                 int pte_idx = 0;
1832                 const int batch_size = min_t(int, pages_to_write_in_pmd, 8);
1833
1834                 start_pte = pte_offset_map_lock(mm, pmd, addr, &pte_lock);
1835                 for (pte = start_pte; pte_idx < batch_size; ++pte, ++pte_idx) {
1836                         int err = insert_page_in_batch_locked(mm, pte,
1837                                 addr, pages[curr_page_idx], prot);
1838                         if (unlikely(err)) {
1839                                 pte_unmap_unlock(start_pte, pte_lock);
1840                                 ret = err;
1841                                 remaining_pages_total -= pte_idx;
1842                                 goto out;
1843                         }
1844                         addr += PAGE_SIZE;
1845                         ++curr_page_idx;
1846                 }
1847                 pte_unmap_unlock(start_pte, pte_lock);
1848                 pages_to_write_in_pmd -= batch_size;
1849                 remaining_pages_total -= batch_size;
1850         }
1851         if (remaining_pages_total)
1852                 goto more;
1853         ret = 0;
1854 out:
1855         *num = remaining_pages_total;
1856         return ret;
1857 }
1858 #endif  /* ifdef pte_index */
1859
1860 /**
1861  * vm_insert_pages - insert multiple pages into user vma, batching the pmd lock.
1862  * @vma: user vma to map to
1863  * @addr: target start user address of these pages
1864  * @pages: source kernel pages
1865  * @num: in: number of pages to map. out: number of pages that were *not*
1866  * mapped. (0 means all pages were successfully mapped).
1867  *
1868  * Preferred over vm_insert_page() when inserting multiple pages.
1869  *
1870  * In case of error, we may have mapped a subset of the provided
1871  * pages. It is the caller's responsibility to account for this case.
1872  *
1873  * The same restrictions apply as in vm_insert_page().
1874  */
1875 int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr,
1876                         struct page **pages, unsigned long *num)
1877 {
1878 #ifdef pte_index
1879         const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1;
1880
1881         if (addr < vma->vm_start || end_addr >= vma->vm_end)
1882                 return -EFAULT;
1883         if (!(vma->vm_flags & VM_MIXEDMAP)) {
1884                 BUG_ON(mmap_read_trylock(vma->vm_mm));
1885                 BUG_ON(vma->vm_flags & VM_PFNMAP);
1886                 vma->vm_flags |= VM_MIXEDMAP;
1887         }
1888         /* Defer page refcount checking till we're about to map that page. */
1889         return insert_pages(vma, addr, pages, num, vma->vm_page_prot);
1890 #else
1891         unsigned long idx = 0, pgcount = *num;
1892         int err = -EINVAL;
1893
1894         for (; idx < pgcount; ++idx) {
1895                 err = vm_insert_page(vma, addr + (PAGE_SIZE * idx), pages[idx]);
1896                 if (err)
1897                         break;
1898         }
1899         *num = pgcount - idx;
1900         return err;
1901 #endif  /* ifdef pte_index */
1902 }
1903 EXPORT_SYMBOL(vm_insert_pages);
1904
1905 /**
1906  * vm_insert_page - insert single page into user vma
1907  * @vma: user vma to map to
1908  * @addr: target user address of this page
1909  * @page: source kernel page
1910  *
1911  * This allows drivers to insert individual pages they've allocated
1912  * into a user vma.
1913  *
1914  * The page has to be a nice clean _individual_ kernel allocation.
1915  * If you allocate a compound page, you need to have marked it as
1916  * such (__GFP_COMP), or manually just split the page up yourself
1917  * (see split_page()).
1918  *
1919  * NOTE! Traditionally this was done with "remap_pfn_range()" which
1920  * took an arbitrary page protection parameter. This doesn't allow
1921  * that. Your vma protection will have to be set up correctly, which
1922  * means that if you want a shared writable mapping, you'd better
1923  * ask for a shared writable mapping!
1924  *
1925  * The page does not need to be reserved.
1926  *
1927  * Usually this function is called from f_op->mmap() handler
1928  * under mm->mmap_lock write-lock, so it can change vma->vm_flags.
1929  * Caller must set VM_MIXEDMAP on vma if it wants to call this
1930  * function from other places, for example from page-fault handler.
1931  *
1932  * Return: %0 on success, negative error code otherwise.
1933  */
1934 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1935                         struct page *page)
1936 {
1937         if (addr < vma->vm_start || addr >= vma->vm_end)
1938                 return -EFAULT;
1939         if (!page_count(page))
1940                 return -EINVAL;
1941         if (!(vma->vm_flags & VM_MIXEDMAP)) {
1942                 BUG_ON(mmap_read_trylock(vma->vm_mm));
1943                 BUG_ON(vma->vm_flags & VM_PFNMAP);
1944                 vma->vm_flags |= VM_MIXEDMAP;
1945         }
1946         return insert_page(vma, addr, page, vma->vm_page_prot);
1947 }
1948 EXPORT_SYMBOL(vm_insert_page);
1949
1950 /*
1951  * __vm_map_pages - maps range of kernel pages into user vma
1952  * @vma: user vma to map to
1953  * @pages: pointer to array of source kernel pages
1954  * @num: number of pages in page array
1955  * @offset: user's requested vm_pgoff
1956  *
1957  * This allows drivers to map range of kernel pages into a user vma.
1958  *
1959  * Return: 0 on success and error code otherwise.
1960  */
1961 static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages,
1962                                 unsigned long num, unsigned long offset)
1963 {
1964         unsigned long count = vma_pages(vma);
1965         unsigned long uaddr = vma->vm_start;
1966         int ret, i;
1967
1968         /* Fail if the user requested offset is beyond the end of the object */
1969         if (offset >= num)
1970                 return -ENXIO;
1971
1972         /* Fail if the user requested size exceeds available object size */
1973         if (count > num - offset)
1974                 return -ENXIO;
1975
1976         for (i = 0; i < count; i++) {
1977                 ret = vm_insert_page(vma, uaddr, pages[offset + i]);
1978                 if (ret < 0)
1979                         return ret;
1980                 uaddr += PAGE_SIZE;
1981         }
1982
1983         return 0;
1984 }
1985
1986 /**
1987  * vm_map_pages - maps range of kernel pages starts with non zero offset
1988  * @vma: user vma to map to
1989  * @pages: pointer to array of source kernel pages
1990  * @num: number of pages in page array
1991  *
1992  * Maps an object consisting of @num pages, catering for the user's
1993  * requested vm_pgoff
1994  *
1995  * If we fail to insert any page into the vma, the function will return
1996  * immediately leaving any previously inserted pages present.  Callers
1997  * from the mmap handler may immediately return the error as their caller
1998  * will destroy the vma, removing any successfully inserted pages. Other
1999  * callers should make their own arrangements for calling unmap_region().
2000  *
2001  * Context: Process context. Called by mmap handlers.
2002  * Return: 0 on success and error code otherwise.
2003  */
2004 int vm_map_pages(struct vm_area_struct *vma, struct page **pages,
2005                                 unsigned long num)
2006 {
2007         return __vm_map_pages(vma, pages, num, vma->vm_pgoff);
2008 }
2009 EXPORT_SYMBOL(vm_map_pages);
2010
2011 /**
2012  * vm_map_pages_zero - map range of kernel pages starts with zero offset
2013  * @vma: user vma to map to
2014  * @pages: pointer to array of source kernel pages
2015  * @num: number of pages in page array
2016  *
2017  * Similar to vm_map_pages(), except that it explicitly sets the offset
2018  * to 0. This function is intended for the drivers that did not consider
2019  * vm_pgoff.
2020  *
2021  * Context: Process context. Called by mmap handlers.
2022  * Return: 0 on success and error code otherwise.
2023  */
2024 int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages,
2025                                 unsigned long num)
2026 {
2027         return __vm_map_pages(vma, pages, num, 0);
2028 }
2029 EXPORT_SYMBOL(vm_map_pages_zero);
2030
2031 static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2032                         pfn_t pfn, pgprot_t prot, bool mkwrite)
2033 {
2034         struct mm_struct *mm = vma->vm_mm;
2035         pte_t *pte, entry;
2036         spinlock_t *ptl;
2037
2038         pte = get_locked_pte(mm, addr, &ptl);
2039         if (!pte)
2040                 return VM_FAULT_OOM;
2041         if (!pte_none(*pte)) {
2042                 if (mkwrite) {
2043                         /*
2044                          * For read faults on private mappings the PFN passed
2045                          * in may not match the PFN we have mapped if the
2046                          * mapped PFN is a writeable COW page.  In the mkwrite
2047                          * case we are creating a writable PTE for a shared
2048                          * mapping and we expect the PFNs to match. If they
2049                          * don't match, we are likely racing with block
2050                          * allocation and mapping invalidation so just skip the
2051                          * update.
2052                          */
2053                         if (pte_pfn(*pte) != pfn_t_to_pfn(pfn)) {
2054                                 WARN_ON_ONCE(!is_zero_pfn(pte_pfn(*pte)));
2055                                 goto out_unlock;
2056                         }
2057                         entry = pte_mkyoung(*pte);
2058                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2059                         if (ptep_set_access_flags(vma, addr, pte, entry, 1))
2060                                 update_mmu_cache(vma, addr, pte);
2061                 }
2062                 goto out_unlock;
2063         }
2064
2065         /* Ok, finally just insert the thing.. */
2066         if (pfn_t_devmap(pfn))
2067                 entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
2068         else
2069                 entry = pte_mkspecial(pfn_t_pte(pfn, prot));
2070
2071         if (mkwrite) {
2072                 entry = pte_mkyoung(entry);
2073                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2074         }
2075
2076         set_pte_at(mm, addr, pte, entry);
2077         update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2078
2079 out_unlock:
2080         pte_unmap_unlock(pte, ptl);
2081         return VM_FAULT_NOPAGE;
2082 }
2083
2084 /**
2085  * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot
2086  * @vma: user vma to map to
2087  * @addr: target user address of this page
2088  * @pfn: source kernel pfn
2089  * @pgprot: pgprot flags for the inserted page
2090  *
2091  * This is exactly like vmf_insert_pfn(), except that it allows drivers
2092  * to override pgprot on a per-page basis.
2093  *
2094  * This only makes sense for IO mappings, and it makes no sense for
2095  * COW mappings.  In general, using multiple vmas is preferable;
2096  * vmf_insert_pfn_prot should only be used if using multiple VMAs is
2097  * impractical.
2098  *
2099  * See vmf_insert_mixed_prot() for a discussion of the implication of using
2100  * a value of @pgprot different from that of @vma->vm_page_prot.
2101  *
2102  * Context: Process context.  May allocate using %GFP_KERNEL.
2103  * Return: vm_fault_t value.
2104  */
2105 vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
2106                         unsigned long pfn, pgprot_t pgprot)
2107 {
2108         /*
2109          * Technically, architectures with pte_special can avoid all these
2110          * restrictions (same for remap_pfn_range).  However we would like
2111          * consistency in testing and feature parity among all, so we should
2112          * try to keep these invariants in place for everybody.
2113          */
2114         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
2115         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
2116                                                 (VM_PFNMAP|VM_MIXEDMAP));
2117         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2118         BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2119
2120         if (addr < vma->vm_start || addr >= vma->vm_end)
2121                 return VM_FAULT_SIGBUS;
2122
2123         if (!pfn_modify_allowed(pfn, pgprot))
2124                 return VM_FAULT_SIGBUS;
2125
2126         track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
2127
2128         return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
2129                         false);
2130 }
2131 EXPORT_SYMBOL(vmf_insert_pfn_prot);
2132
2133 /**
2134  * vmf_insert_pfn - insert single pfn into user vma
2135  * @vma: user vma to map to
2136  * @addr: target user address of this page
2137  * @pfn: source kernel pfn
2138  *
2139  * Similar to vm_insert_page, this allows drivers to insert individual pages
2140  * they've allocated into a user vma. Same comments apply.
2141  *
2142  * This function should only be called from a vm_ops->fault handler, and
2143  * in that case the handler should return the result of this function.
2144  *
2145  * vma cannot be a COW mapping.
2146  *
2147  * As this is called only for pages that do not currently exist, we
2148  * do not need to flush old virtual caches or the TLB.
2149  *
2150  * Context: Process context.  May allocate using %GFP_KERNEL.
2151  * Return: vm_fault_t value.
2152  */
2153 vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2154                         unsigned long pfn)
2155 {
2156         return vmf_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
2157 }
2158 EXPORT_SYMBOL(vmf_insert_pfn);
2159
2160 static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
2161 {
2162         /* these checks mirror the abort conditions in vm_normal_page */
2163         if (vma->vm_flags & VM_MIXEDMAP)
2164                 return true;
2165         if (pfn_t_devmap(pfn))
2166                 return true;
2167         if (pfn_t_special(pfn))
2168                 return true;
2169         if (is_zero_pfn(pfn_t_to_pfn(pfn)))
2170                 return true;
2171         return false;
2172 }
2173
2174 static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
2175                 unsigned long addr, pfn_t pfn, pgprot_t pgprot,
2176                 bool mkwrite)
2177 {
2178         int err;
2179
2180         BUG_ON(!vm_mixed_ok(vma, pfn));
2181
2182         if (addr < vma->vm_start || addr >= vma->vm_end)
2183                 return VM_FAULT_SIGBUS;
2184
2185         track_pfn_insert(vma, &pgprot, pfn);
2186
2187         if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot))
2188                 return VM_FAULT_SIGBUS;
2189
2190         /*
2191          * If we don't have pte special, then we have to use the pfn_valid()
2192          * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2193          * refcount the page if pfn_valid is true (hence insert_page rather
2194          * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
2195          * without pte special, it would there be refcounted as a normal page.
2196          */
2197         if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) &&
2198             !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
2199                 struct page *page;
2200
2201                 /*
2202                  * At this point we are committed to insert_page()
2203                  * regardless of whether the caller specified flags that
2204                  * result in pfn_t_has_page() == false.
2205                  */
2206                 page = pfn_to_page(pfn_t_to_pfn(pfn));
2207                 err = insert_page(vma, addr, page, pgprot);
2208         } else {
2209                 return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
2210         }
2211
2212         if (err == -ENOMEM)
2213                 return VM_FAULT_OOM;
2214         if (err < 0 && err != -EBUSY)
2215                 return VM_FAULT_SIGBUS;
2216
2217         return VM_FAULT_NOPAGE;
2218 }
2219
2220 /**
2221  * vmf_insert_mixed_prot - insert single pfn into user vma with specified pgprot
2222  * @vma: user vma to map to
2223  * @addr: target user address of this page
2224  * @pfn: source kernel pfn
2225  * @pgprot: pgprot flags for the inserted page
2226  *
2227  * This is exactly like vmf_insert_mixed(), except that it allows drivers
2228  * to override pgprot on a per-page basis.
2229  *
2230  * Typically this function should be used by drivers to set caching- and
2231  * encryption bits different than those of @vma->vm_page_prot, because
2232  * the caching- or encryption mode may not be known at mmap() time.
2233  * This is ok as long as @vma->vm_page_prot is not used by the core vm
2234  * to set caching and encryption bits for those vmas (except for COW pages).
2235  * This is ensured by core vm only modifying these page table entries using
2236  * functions that don't touch caching- or encryption bits, using pte_modify()
2237  * if needed. (See for example mprotect()).
2238  * Also when new page-table entries are created, this is only done using the
2239  * fault() callback, and never using the value of vma->vm_page_prot,
2240  * except for page-table entries that point to anonymous pages as the result
2241  * of COW.
2242  *
2243  * Context: Process context.  May allocate using %GFP_KERNEL.
2244  * Return: vm_fault_t value.
2245  */
2246 vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
2247                                  pfn_t pfn, pgprot_t pgprot)
2248 {
2249         return __vm_insert_mixed(vma, addr, pfn, pgprot, false);
2250 }
2251 EXPORT_SYMBOL(vmf_insert_mixed_prot);
2252
2253 vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2254                 pfn_t pfn)
2255 {
2256         return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, false);
2257 }
2258 EXPORT_SYMBOL(vmf_insert_mixed);
2259
2260 /*
2261  *  If the insertion of PTE failed because someone else already added a
2262  *  different entry in the mean time, we treat that as success as we assume
2263  *  the same entry was actually inserted.
2264  */
2265 vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
2266                 unsigned long addr, pfn_t pfn)
2267 {
2268         return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, true);
2269 }
2270 EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);
2271
2272 /*
2273  * maps a range of physical memory into the requested pages. the old
2274  * mappings are removed. any references to nonexistent pages results
2275  * in null mappings (currently treated as "copy-on-access")
2276  */
2277 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2278                         unsigned long addr, unsigned long end,
2279                         unsigned long pfn, pgprot_t prot)
2280 {
2281         pte_t *pte, *mapped_pte;
2282         spinlock_t *ptl;
2283         int err = 0;
2284
2285         mapped_pte = pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2286         if (!pte)
2287                 return -ENOMEM;
2288         arch_enter_lazy_mmu_mode();
2289         do {
2290                 BUG_ON(!pte_none(*pte));
2291                 if (!pfn_modify_allowed(pfn, prot)) {
2292                         err = -EACCES;
2293                         break;
2294                 }
2295                 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2296                 pfn++;
2297         } while (pte++, addr += PAGE_SIZE, addr != end);
2298         arch_leave_lazy_mmu_mode();
2299         pte_unmap_unlock(mapped_pte, ptl);
2300         return err;
2301 }
2302
2303 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2304                         unsigned long addr, unsigned long end,
2305                         unsigned long pfn, pgprot_t prot)
2306 {
2307         pmd_t *pmd;
2308         unsigned long next;
2309         int err;
2310
2311         pfn -= addr >> PAGE_SHIFT;
2312         pmd = pmd_alloc(mm, pud, addr);
2313         if (!pmd)
2314                 return -ENOMEM;
2315         VM_BUG_ON(pmd_trans_huge(*pmd));
2316         do {
2317                 next = pmd_addr_end(addr, end);
2318                 err = remap_pte_range(mm, pmd, addr, next,
2319                                 pfn + (addr >> PAGE_SHIFT), prot);
2320                 if (err)
2321                         return err;
2322         } while (pmd++, addr = next, addr != end);
2323         return 0;
2324 }
2325
2326 static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
2327                         unsigned long addr, unsigned long end,
2328                         unsigned long pfn, pgprot_t prot)
2329 {
2330         pud_t *pud;
2331         unsigned long next;
2332         int err;
2333
2334         pfn -= addr >> PAGE_SHIFT;
2335         pud = pud_alloc(mm, p4d, addr);
2336         if (!pud)
2337                 return -ENOMEM;
2338         do {
2339                 next = pud_addr_end(addr, end);
2340                 err = remap_pmd_range(mm, pud, addr, next,
2341                                 pfn + (addr >> PAGE_SHIFT), prot);
2342                 if (err)
2343                         return err;
2344         } while (pud++, addr = next, addr != end);
2345         return 0;
2346 }
2347
2348 static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2349                         unsigned long addr, unsigned long end,
2350                         unsigned long pfn, pgprot_t prot)
2351 {
2352         p4d_t *p4d;
2353         unsigned long next;
2354         int err;
2355
2356         pfn -= addr >> PAGE_SHIFT;
2357         p4d = p4d_alloc(mm, pgd, addr);
2358         if (!p4d)
2359                 return -ENOMEM;
2360         do {
2361                 next = p4d_addr_end(addr, end);
2362                 err = remap_pud_range(mm, p4d, addr, next,
2363                                 pfn + (addr >> PAGE_SHIFT), prot);
2364                 if (err)
2365                         return err;
2366         } while (p4d++, addr = next, addr != end);
2367         return 0;
2368 }
2369
2370 /*
2371  * Variant of remap_pfn_range that does not call track_pfn_remap.  The caller
2372  * must have pre-validated the caching bits of the pgprot_t.
2373  */
2374 int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr,
2375                 unsigned long pfn, unsigned long size, pgprot_t prot)
2376 {
2377         pgd_t *pgd;
2378         unsigned long next;
2379         unsigned long end = addr + PAGE_ALIGN(size);
2380         struct mm_struct *mm = vma->vm_mm;
2381         int err;
2382
2383         if (WARN_ON_ONCE(!PAGE_ALIGNED(addr)))
2384                 return -EINVAL;
2385
2386         /*
2387          * Physically remapped pages are special. Tell the
2388          * rest of the world about it:
2389          *   VM_IO tells people not to look at these pages
2390          *      (accesses can have side effects).
2391          *   VM_PFNMAP tells the core MM that the base pages are just
2392          *      raw PFN mappings, and do not have a "struct page" associated
2393          *      with them.
2394          *   VM_DONTEXPAND
2395          *      Disable vma merging and expanding with mremap().
2396          *   VM_DONTDUMP
2397          *      Omit vma from core dump, even when VM_IO turned off.
2398          *
2399          * There's a horrible special case to handle copy-on-write
2400          * behaviour that some programs depend on. We mark the "original"
2401          * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2402          * See vm_normal_page() for details.
2403          */
2404         if (is_cow_mapping(vma->vm_flags)) {
2405                 if (addr != vma->vm_start || end != vma->vm_end)
2406                         return -EINVAL;
2407                 vma->vm_pgoff = pfn;
2408         }
2409
2410         vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
2411
2412         BUG_ON(addr >= end);
2413         pfn -= addr >> PAGE_SHIFT;
2414         pgd = pgd_offset(mm, addr);
2415         flush_cache_range(vma, addr, end);
2416         do {
2417                 next = pgd_addr_end(addr, end);
2418                 err = remap_p4d_range(mm, pgd, addr, next,
2419                                 pfn + (addr >> PAGE_SHIFT), prot);
2420                 if (err)
2421                         return err;
2422         } while (pgd++, addr = next, addr != end);
2423
2424         return 0;
2425 }
2426
2427 /**
2428  * remap_pfn_range - remap kernel memory to userspace
2429  * @vma: user vma to map to
2430  * @addr: target page aligned user address to start at
2431  * @pfn: page frame number of kernel physical memory address
2432  * @size: size of mapping area
2433  * @prot: page protection flags for this mapping
2434  *
2435  * Note: this is only safe if the mm semaphore is held when called.
2436  *
2437  * Return: %0 on success, negative error code otherwise.
2438  */
2439 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2440                     unsigned long pfn, unsigned long size, pgprot_t prot)
2441 {
2442         int err;
2443
2444         err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
2445         if (err)
2446                 return -EINVAL;
2447
2448         err = remap_pfn_range_notrack(vma, addr, pfn, size, prot);
2449         if (err)
2450                 untrack_pfn(vma, pfn, PAGE_ALIGN(size));
2451         return err;
2452 }
2453 EXPORT_SYMBOL(remap_pfn_range);
2454
2455 /**
2456  * vm_iomap_memory - remap memory to userspace
2457  * @vma: user vma to map to
2458  * @start: start of the physical memory to be mapped
2459  * @len: size of area
2460  *
2461  * This is a simplified io_remap_pfn_range() for common driver use. The
2462  * driver just needs to give us the physical memory range to be mapped,
2463  * we'll figure out the rest from the vma information.
2464  *
2465  * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2466  * whatever write-combining details or similar.
2467  *
2468  * Return: %0 on success, negative error code otherwise.
2469  */
2470 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2471 {
2472         unsigned long vm_len, pfn, pages;
2473
2474         /* Check that the physical memory area passed in looks valid */
2475         if (start + len < start)
2476                 return -EINVAL;
2477         /*
2478          * You *really* shouldn't map things that aren't page-aligned,
2479          * but we've historically allowed it because IO memory might
2480          * just have smaller alignment.
2481          */
2482         len += start & ~PAGE_MASK;
2483         pfn = start >> PAGE_SHIFT;
2484         pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2485         if (pfn + pages < pfn)
2486                 return -EINVAL;
2487
2488         /* We start the mapping 'vm_pgoff' pages into the area */
2489         if (vma->vm_pgoff > pages)
2490                 return -EINVAL;
2491         pfn += vma->vm_pgoff;
2492         pages -= vma->vm_pgoff;
2493
2494         /* Can we fit all of the mapping? */
2495         vm_len = vma->vm_end - vma->vm_start;
2496         if (vm_len >> PAGE_SHIFT > pages)
2497                 return -EINVAL;
2498
2499         /* Ok, let it rip */
2500         return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2501 }
2502 EXPORT_SYMBOL(vm_iomap_memory);
2503
2504 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2505                                      unsigned long addr, unsigned long end,
2506                                      pte_fn_t fn, void *data, bool create,
2507                                      pgtbl_mod_mask *mask)
2508 {
2509         pte_t *pte, *mapped_pte;
2510         int err = 0;
2511         spinlock_t *ptl;
2512
2513         if (create) {
2514                 mapped_pte = pte = (mm == &init_mm) ?
2515                         pte_alloc_kernel_track(pmd, addr, mask) :
2516                         pte_alloc_map_lock(mm, pmd, addr, &ptl);
2517                 if (!pte)
2518                         return -ENOMEM;
2519         } else {
2520                 mapped_pte = pte = (mm == &init_mm) ?
2521                         pte_offset_kernel(pmd, addr) :
2522                         pte_offset_map_lock(mm, pmd, addr, &ptl);
2523         }
2524
2525         BUG_ON(pmd_huge(*pmd));
2526
2527         arch_enter_lazy_mmu_mode();
2528
2529         if (fn) {
2530                 do {
2531                         if (create || !pte_none(*pte)) {
2532                                 err = fn(pte++, addr, data);
2533                                 if (err)
2534                                         break;
2535                         }
2536                 } while (addr += PAGE_SIZE, addr != end);
2537         }
2538         *mask |= PGTBL_PTE_MODIFIED;
2539
2540         arch_leave_lazy_mmu_mode();
2541
2542         if (mm != &init_mm)
2543                 pte_unmap_unlock(mapped_pte, ptl);
2544         return err;
2545 }
2546
2547 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2548                                      unsigned long addr, unsigned long end,
2549                                      pte_fn_t fn, void *data, bool create,
2550                                      pgtbl_mod_mask *mask)
2551 {
2552         pmd_t *pmd;
2553         unsigned long next;
2554         int err = 0;
2555
2556         BUG_ON(pud_huge(*pud));
2557
2558         if (create) {
2559                 pmd = pmd_alloc_track(mm, pud, addr, mask);
2560                 if (!pmd)
2561                         return -ENOMEM;
2562         } else {
2563                 pmd = pmd_offset(pud, addr);
2564         }
2565         do {
2566                 next = pmd_addr_end(addr, end);
2567                 if (pmd_none(*pmd) && !create)
2568                         continue;
2569                 if (WARN_ON_ONCE(pmd_leaf(*pmd)))
2570                         return -EINVAL;
2571                 if (!pmd_none(*pmd) && WARN_ON_ONCE(pmd_bad(*pmd))) {
2572                         if (!create)
2573                                 continue;
2574                         pmd_clear_bad(pmd);
2575                 }
2576                 err = apply_to_pte_range(mm, pmd, addr, next,
2577                                          fn, data, create, mask);
2578                 if (err)
2579                         break;
2580         } while (pmd++, addr = next, addr != end);
2581
2582         return err;
2583 }
2584
2585 static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
2586                                      unsigned long addr, unsigned long end,
2587                                      pte_fn_t fn, void *data, bool create,
2588                                      pgtbl_mod_mask *mask)
2589 {
2590         pud_t *pud;
2591         unsigned long next;
2592         int err = 0;
2593
2594         if (create) {
2595                 pud = pud_alloc_track(mm, p4d, addr, mask);
2596                 if (!pud)
2597                         return -ENOMEM;
2598         } else {
2599                 pud = pud_offset(p4d, addr);
2600         }
2601         do {
2602                 next = pud_addr_end(addr, end);
2603                 if (pud_none(*pud) && !create)
2604                         continue;
2605                 if (WARN_ON_ONCE(pud_leaf(*pud)))
2606                         return -EINVAL;
2607                 if (!pud_none(*pud) && WARN_ON_ONCE(pud_bad(*pud))) {
2608                         if (!create)
2609                                 continue;
2610                         pud_clear_bad(pud);
2611                 }
2612                 err = apply_to_pmd_range(mm, pud, addr, next,
2613                                          fn, data, create, mask);
2614                 if (err)
2615                         break;
2616         } while (pud++, addr = next, addr != end);
2617
2618         return err;
2619 }
2620
2621 static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2622                                      unsigned long addr, unsigned long end,
2623                                      pte_fn_t fn, void *data, bool create,
2624                                      pgtbl_mod_mask *mask)
2625 {
2626         p4d_t *p4d;
2627         unsigned long next;
2628         int err = 0;
2629
2630         if (create) {
2631                 p4d = p4d_alloc_track(mm, pgd, addr, mask);
2632                 if (!p4d)
2633                         return -ENOMEM;
2634         } else {
2635                 p4d = p4d_offset(pgd, addr);
2636         }
2637         do {
2638                 next = p4d_addr_end(addr, end);
2639                 if (p4d_none(*p4d) && !create)
2640                         continue;
2641                 if (WARN_ON_ONCE(p4d_leaf(*p4d)))
2642                         return -EINVAL;
2643                 if (!p4d_none(*p4d) && WARN_ON_ONCE(p4d_bad(*p4d))) {
2644                         if (!create)
2645                                 continue;
2646                         p4d_clear_bad(p4d);
2647                 }
2648                 err = apply_to_pud_range(mm, p4d, addr, next,
2649                                          fn, data, create, mask);
2650                 if (err)
2651                         break;
2652         } while (p4d++, addr = next, addr != end);
2653
2654         return err;
2655 }
2656
2657 static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2658                                  unsigned long size, pte_fn_t fn,
2659                                  void *data, bool create)
2660 {
2661         pgd_t *pgd;
2662         unsigned long start = addr, next;
2663         unsigned long end = addr + size;
2664         pgtbl_mod_mask mask = 0;
2665         int err = 0;
2666
2667         if (WARN_ON(addr >= end))
2668                 return -EINVAL;
2669
2670         pgd = pgd_offset(mm, addr);
2671         do {
2672                 next = pgd_addr_end(addr, end);
2673                 if (pgd_none(*pgd) && !create)
2674                         continue;
2675                 if (WARN_ON_ONCE(pgd_leaf(*pgd)))
2676                         return -EINVAL;
2677                 if (!pgd_none(*pgd) && WARN_ON_ONCE(pgd_bad(*pgd))) {
2678                         if (!create)
2679                                 continue;
2680                         pgd_clear_bad(pgd);
2681                 }
2682                 err = apply_to_p4d_range(mm, pgd, addr, next,
2683                                          fn, data, create, &mask);
2684                 if (err)
2685                         break;
2686         } while (pgd++, addr = next, addr != end);
2687
2688         if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
2689                 arch_sync_kernel_mappings(start, start + size);
2690
2691         return err;
2692 }
2693
2694 /*
2695  * Scan a region of virtual memory, filling in page tables as necessary
2696  * and calling a provided function on each leaf page table.
2697  */
2698 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2699                         unsigned long size, pte_fn_t fn, void *data)
2700 {
2701         return __apply_to_page_range(mm, addr, size, fn, data, true);
2702 }
2703 EXPORT_SYMBOL_GPL(apply_to_page_range);
2704
2705 /*
2706  * Scan a region of virtual memory, calling a provided function on
2707  * each leaf page table where it exists.
2708  *
2709  * Unlike apply_to_page_range, this does _not_ fill in page tables
2710  * where they are absent.
2711  */
2712 int apply_to_existing_page_range(struct mm_struct *mm, unsigned long addr,
2713                                  unsigned long size, pte_fn_t fn, void *data)
2714 {
2715         return __apply_to_page_range(mm, addr, size, fn, data, false);
2716 }
2717 EXPORT_SYMBOL_GPL(apply_to_existing_page_range);
2718
2719 /*
2720  * handle_pte_fault chooses page fault handler according to an entry which was
2721  * read non-atomically.  Before making any commitment, on those architectures
2722  * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
2723  * parts, do_swap_page must check under lock before unmapping the pte and
2724  * proceeding (but do_wp_page is only called after already making such a check;
2725  * and do_anonymous_page can safely check later on).
2726  */
2727 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2728                                 pte_t *page_table, pte_t orig_pte)
2729 {
2730         int same = 1;
2731 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPTION)
2732         if (sizeof(pte_t) > sizeof(unsigned long)) {
2733                 spinlock_t *ptl = pte_lockptr(mm, pmd);
2734                 spin_lock(ptl);
2735                 same = pte_same(*page_table, orig_pte);
2736                 spin_unlock(ptl);
2737         }
2738 #endif
2739         pte_unmap(page_table);
2740         return same;
2741 }
2742
2743 static inline bool cow_user_page(struct page *dst, struct page *src,
2744                                  struct vm_fault *vmf)
2745 {
2746         bool ret;
2747         void *kaddr;
2748         void __user *uaddr;
2749         bool locked = false;
2750         struct vm_area_struct *vma = vmf->vma;
2751         struct mm_struct *mm = vma->vm_mm;
2752         unsigned long addr = vmf->address;
2753
2754         if (likely(src)) {
2755                 copy_user_highpage(dst, src, addr, vma);
2756                 return true;
2757         }
2758
2759         /*
2760          * If the source page was a PFN mapping, we don't have
2761          * a "struct page" for it. We do a best-effort copy by
2762          * just copying from the original user address. If that
2763          * fails, we just zero-fill it. Live with it.
2764          */
2765         kaddr = kmap_atomic(dst);
2766         uaddr = (void __user *)(addr & PAGE_MASK);
2767
2768         /*
2769          * On architectures with software "accessed" bits, we would
2770          * take a double page fault, so mark it accessed here.
2771          */
2772         if (arch_faults_on_old_pte() && !pte_young(vmf->orig_pte)) {
2773                 pte_t entry;
2774
2775                 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
2776                 locked = true;
2777                 if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2778                         /*
2779                          * Other thread has already handled the fault
2780                          * and update local tlb only
2781                          */
2782                         update_mmu_tlb(vma, addr, vmf->pte);
2783                         ret = false;
2784                         goto pte_unlock;
2785                 }
2786
2787                 entry = pte_mkyoung(vmf->orig_pte);
2788                 if (ptep_set_access_flags(vma, addr, vmf->pte, entry, 0))
2789                         update_mmu_cache(vma, addr, vmf->pte);
2790         }
2791
2792         /*
2793          * This really shouldn't fail, because the page is there
2794          * in the page tables. But it might just be unreadable,
2795          * in which case we just give up and fill the result with
2796          * zeroes.
2797          */
2798         if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
2799                 if (locked)
2800                         goto warn;
2801
2802                 /* Re-validate under PTL if the page is still mapped */
2803                 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
2804                 locked = true;
2805                 if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2806                         /* The PTE changed under us, update local tlb */
2807                         update_mmu_tlb(vma, addr, vmf->pte);
2808                         ret = false;
2809                         goto pte_unlock;
2810                 }
2811
2812                 /*
2813                  * The same page can be mapped back since last copy attempt.
2814                  * Try to copy again under PTL.
2815                  */
2816                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
2817                         /*
2818                          * Give a warn in case there can be some obscure
2819                          * use-case
2820                          */
2821 warn:
2822                         WARN_ON_ONCE(1);
2823                         clear_page(kaddr);
2824                 }
2825         }
2826
2827         ret = true;
2828
2829 pte_unlock:
2830         if (locked)
2831                 pte_unmap_unlock(vmf->pte, vmf->ptl);
2832         kunmap_atomic(kaddr);
2833         flush_dcache_page(dst);
2834
2835         return ret;
2836 }
2837
2838 static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2839 {
2840         struct file *vm_file = vma->vm_file;
2841
2842         if (vm_file)
2843                 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2844
2845         /*
2846          * Special mappings (e.g. VDSO) do not have any file so fake
2847          * a default GFP_KERNEL for them.
2848          */
2849         return GFP_KERNEL;
2850 }
2851
2852 /*
2853  * Notify the address space that the page is about to become writable so that
2854  * it can prohibit this or wait for the page to get into an appropriate state.
2855  *
2856  * We do this without the lock held, so that it can sleep if it needs to.
2857  */
2858 static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
2859 {
2860         vm_fault_t ret;
2861         struct page *page = vmf->page;
2862         unsigned int old_flags = vmf->flags;
2863
2864         vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2865
2866         if (vmf->vma->vm_file &&
2867             IS_SWAPFILE(vmf->vma->vm_file->f_mapping->host))
2868                 return VM_FAULT_SIGBUS;
2869
2870         ret = vmf->vma->vm_ops->page_mkwrite(vmf);
2871         /* Restore original flags so that caller is not surprised */
2872         vmf->flags = old_flags;
2873         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2874                 return ret;
2875         if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2876                 lock_page(page);
2877                 if (!page->mapping) {
2878                         unlock_page(page);
2879                         return 0; /* retry */
2880                 }
2881                 ret |= VM_FAULT_LOCKED;
2882         } else
2883                 VM_BUG_ON_PAGE(!PageLocked(page), page);
2884         return ret;
2885 }
2886
2887 /*
2888  * Handle dirtying of a page in shared file mapping on a write fault.
2889  *
2890  * The function expects the page to be locked and unlocks it.
2891  */
2892 static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf)
2893 {
2894         struct vm_area_struct *vma = vmf->vma;
2895         struct address_space *mapping;
2896         struct page *page = vmf->page;
2897         bool dirtied;
2898         bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
2899
2900         dirtied = set_page_dirty(page);
2901         VM_BUG_ON_PAGE(PageAnon(page), page);
2902         /*
2903          * Take a local copy of the address_space - page.mapping may be zeroed
2904          * by truncate after unlock_page().   The address_space itself remains
2905          * pinned by vma->vm_file's reference.  We rely on unlock_page()'s
2906          * release semantics to prevent the compiler from undoing this copying.
2907          */
2908         mapping = page_rmapping(page);
2909         unlock_page(page);
2910
2911         if (!page_mkwrite)
2912                 file_update_time(vma->vm_file);
2913
2914         /*
2915          * Throttle page dirtying rate down to writeback speed.
2916          *
2917          * mapping may be NULL here because some device drivers do not
2918          * set page.mapping but still dirty their pages
2919          *
2920          * Drop the mmap_lock before waiting on IO, if we can. The file
2921          * is pinning the mapping, as per above.
2922          */
2923         if ((dirtied || page_mkwrite) && mapping) {
2924                 struct file *fpin;
2925
2926                 fpin = maybe_unlock_mmap_for_io(vmf, NULL);
2927                 balance_dirty_pages_ratelimited(mapping);
2928                 if (fpin) {
2929                         fput(fpin);
2930                         return VM_FAULT_RETRY;
2931                 }
2932         }
2933
2934         return 0;
2935 }
2936
2937 /*
2938  * Handle write page faults for pages that can be reused in the current vma
2939  *
2940  * This can happen either due to the mapping being with the VM_SHARED flag,
2941  * or due to us being the last reference standing to the page. In either
2942  * case, all we need to do here is to mark the page as writable and update
2943  * any related book-keeping.
2944  */
2945 static inline void wp_page_reuse(struct vm_fault *vmf)
2946         __releases(vmf->ptl)
2947 {
2948         struct vm_area_struct *vma = vmf->vma;
2949         struct page *page = vmf->page;
2950         pte_t entry;
2951         /*
2952          * Clear the pages cpupid information as the existing
2953          * information potentially belongs to a now completely
2954          * unrelated process.
2955          */
2956         if (page)
2957                 page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
2958
2959         flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2960         entry = pte_mkyoung(vmf->orig_pte);
2961         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2962         if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
2963                 update_mmu_cache(vma, vmf->address, vmf->pte);
2964         pte_unmap_unlock(vmf->pte, vmf->ptl);
2965         count_vm_event(PGREUSE);
2966 }
2967
2968 /*
2969  * Handle the case of a page which we actually need to copy to a new page.
2970  *
2971  * Called with mmap_lock locked and the old page referenced, but
2972  * without the ptl held.
2973  *
2974  * High level logic flow:
2975  *
2976  * - Allocate a page, copy the content of the old page to the new one.
2977  * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2978  * - Take the PTL. If the pte changed, bail out and release the allocated page
2979  * - If the pte is still the way we remember it, update the page table and all
2980  *   relevant references. This includes dropping the reference the page-table
2981  *   held to the old page, as well as updating the rmap.
2982  * - In any case, unlock the PTL and drop the reference we took to the old page.
2983  */
2984 static vm_fault_t wp_page_copy(struct vm_fault *vmf)
2985 {
2986         struct vm_area_struct *vma = vmf->vma;
2987         struct mm_struct *mm = vma->vm_mm;
2988         struct page *old_page = vmf->page;
2989         struct page *new_page = NULL;
2990         pte_t entry;
2991         int page_copied = 0;
2992         struct mmu_notifier_range range;
2993
2994         if (unlikely(anon_vma_prepare(vma)))
2995                 goto oom;
2996
2997         if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
2998                 new_page = alloc_zeroed_user_highpage_movable(vma,
2999                                                               vmf->address);
3000                 if (!new_page)
3001                         goto oom;
3002         } else {
3003                 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
3004                                 vmf->address);
3005                 if (!new_page)
3006                         goto oom;
3007
3008                 if (!cow_user_page(new_page, old_page, vmf)) {
3009                         /*
3010                          * COW failed, if the fault was solved by other,
3011                          * it's fine. If not, userspace would re-fault on
3012                          * the same address and we will handle the fault
3013                          * from the second attempt.
3014                          */
3015                         put_page(new_page);
3016                         if (old_page)
3017                                 put_page(old_page);
3018                         return 0;
3019                 }
3020         }
3021
3022         if (mem_cgroup_charge(new_page, mm, GFP_KERNEL))
3023                 goto oom_free_new;
3024         cgroup_throttle_swaprate(new_page, GFP_KERNEL);
3025
3026         __SetPageUptodate(new_page);
3027
3028         mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm,
3029                                 vmf->address & PAGE_MASK,
3030                                 (vmf->address & PAGE_MASK) + PAGE_SIZE);
3031         mmu_notifier_invalidate_range_start(&range);
3032
3033         /*
3034          * Re-check the pte - we dropped the lock
3035          */
3036         vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
3037         if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
3038                 if (old_page) {
3039                         if (!PageAnon(old_page)) {
3040                                 dec_mm_counter_fast(mm,
3041                                                 mm_counter_file(old_page));
3042                                 inc_mm_counter_fast(mm, MM_ANONPAGES);
3043                         }
3044                 } else {
3045                         inc_mm_counter_fast(mm, MM_ANONPAGES);
3046                 }
3047                 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
3048                 entry = mk_pte(new_page, vma->vm_page_prot);
3049                 entry = pte_sw_mkyoung(entry);
3050                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3051
3052                 /*
3053                  * Clear the pte entry and flush it first, before updating the
3054                  * pte with the new entry, to keep TLBs on different CPUs in
3055                  * sync. This code used to set the new PTE then flush TLBs, but
3056                  * that left a window where the new PTE could be loaded into
3057                  * some TLBs while the old PTE remains in others.
3058                  */
3059                 ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
3060                 page_add_new_anon_rmap(new_page, vma, vmf->address, false);
3061                 lru_cache_add_inactive_or_unevictable(new_page, vma);
3062                 /*
3063                  * We call the notify macro here because, when using secondary
3064                  * mmu page tables (such as kvm shadow page tables), we want the
3065                  * new page to be mapped directly into the secondary page table.
3066                  */
3067                 set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
3068                 update_mmu_cache(vma, vmf->address, vmf->pte);
3069                 if (old_page) {
3070                         /*
3071                          * Only after switching the pte to the new page may
3072                          * we remove the mapcount here. Otherwise another
3073                          * process may come and find the rmap count decremented
3074                          * before the pte is switched to the new page, and
3075                          * "reuse" the old page writing into it while our pte
3076                          * here still points into it and can be read by other
3077                          * threads.
3078                          *
3079                          * The critical issue is to order this
3080                          * page_remove_rmap with the ptp_clear_flush above.
3081                          * Those stores are ordered by (if nothing else,)
3082                          * the barrier present in the atomic_add_negative
3083                          * in page_remove_rmap.
3084                          *
3085                          * Then the TLB flush in ptep_clear_flush ensures that
3086                          * no process can access the old page before the
3087                          * decremented mapcount is visible. And the old page
3088                          * cannot be reused until after the decremented
3089                          * mapcount is visible. So transitively, TLBs to
3090                          * old page will be flushed before it can be reused.
3091                          */
3092                         page_remove_rmap(old_page, false);
3093                 }
3094
3095                 /* Free the old page.. */
3096                 new_page = old_page;
3097                 page_copied = 1;
3098         } else {
3099                 update_mmu_tlb(vma, vmf->address, vmf->pte);
3100         }
3101
3102         if (new_page)
3103                 put_page(new_page);
3104
3105         pte_unmap_unlock(vmf->pte, vmf->ptl);
3106         /*
3107          * No need to double call mmu_notifier->invalidate_range() callback as
3108          * the above ptep_clear_flush_notify() did already call it.
3109          */
3110         mmu_notifier_invalidate_range_only_end(&range);
3111         if (old_page) {
3112                 /*
3113                  * Don't let another task, with possibly unlocked vma,
3114                  * keep the mlocked page.
3115                  */
3116                 if (page_copied && (vma->vm_flags & VM_LOCKED)) {
3117                         lock_page(old_page);    /* LRU manipulation */
3118                         if (PageMlocked(old_page))
3119                                 munlock_vma_page(old_page);
3120                         unlock_page(old_page);
3121                 }
3122                 if (page_copied)
3123                         free_swap_cache(old_page);
3124                 put_page(old_page);
3125         }
3126         return page_copied ? VM_FAULT_WRITE : 0;
3127 oom_free_new:
3128         put_page(new_page);
3129 oom:
3130         if (old_page)
3131                 put_page(old_page);
3132         return VM_FAULT_OOM;
3133 }
3134
3135 /**
3136  * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
3137  *                        writeable once the page is prepared
3138  *
3139  * @vmf: structure describing the fault
3140  *
3141  * This function handles all that is needed to finish a write page fault in a
3142  * shared mapping due to PTE being read-only once the mapped page is prepared.
3143  * It handles locking of PTE and modifying it.
3144  *
3145  * The function expects the page to be locked or other protection against
3146  * concurrent faults / writeback (such as DAX radix tree locks).
3147  *
3148  * Return: %0 on success, %VM_FAULT_NOPAGE when PTE got changed before
3149  * we acquired PTE lock.
3150  */
3151 vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf)
3152 {
3153         WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
3154         vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
3155                                        &vmf->ptl);
3156         /*
3157          * We might have raced with another page fault while we released the
3158          * pte_offset_map_lock.
3159          */
3160         if (!pte_same(*vmf->pte, vmf->orig_pte)) {
3161                 update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
3162                 pte_unmap_unlock(vmf->pte, vmf->ptl);
3163                 return VM_FAULT_NOPAGE;
3164         }
3165         wp_page_reuse(vmf);
3166         return 0;
3167 }
3168
3169 /*
3170  * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
3171  * mapping
3172  */
3173 static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
3174 {
3175         struct vm_area_struct *vma = vmf->vma;
3176
3177         if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
3178                 vm_fault_t ret;
3179
3180                 pte_unmap_unlock(vmf->pte, vmf->ptl);
3181                 vmf->flags |= FAULT_FLAG_MKWRITE;
3182                 ret = vma->vm_ops->pfn_mkwrite(vmf);
3183                 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
3184                         return ret;
3185                 return finish_mkwrite_fault(vmf);
3186         }
3187         wp_page_reuse(vmf);
3188         return VM_FAULT_WRITE;
3189 }
3190
3191 static vm_fault_t wp_page_shared(struct vm_fault *vmf)
3192         __releases(vmf->ptl)
3193 {
3194         struct vm_area_struct *vma = vmf->vma;
3195         vm_fault_t ret = VM_FAULT_WRITE;
3196
3197         get_page(vmf->page);
3198
3199         if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
3200                 vm_fault_t tmp;
3201
3202                 pte_unmap_unlock(vmf->pte, vmf->ptl);
3203                 tmp = do_page_mkwrite(vmf);
3204                 if (unlikely(!tmp || (tmp &
3205                                       (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3206                         put_page(vmf->page);
3207                         return tmp;
3208                 }
3209                 tmp = finish_mkwrite_fault(vmf);
3210                 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3211                         unlock_page(vmf->page);
3212                         put_page(vmf->page);
3213                         return tmp;
3214                 }
3215         } else {
3216                 wp_page_reuse(vmf);
3217                 lock_page(vmf->page);
3218         }
3219         ret |= fault_dirty_shared_page(vmf);
3220         put_page(vmf->page);
3221
3222         return ret;
3223 }
3224
3225 /*
3226  * This routine handles present pages, when users try to write
3227  * to a shared page. It is done by copying the page to a new address
3228  * and decrementing the shared-page counter for the old page.
3229  *
3230  * Note that this routine assumes that the protection checks have been
3231  * done by the caller (the low-level page fault routine in most cases).
3232  * Thus we can safely just mark it writable once we've done any necessary
3233  * COW.
3234  *
3235  * We also mark the page dirty at this point even though the page will
3236  * change only once the write actually happens. This avoids a few races,
3237  * and potentially makes it more efficient.
3238  *
3239  * We enter with non-exclusive mmap_lock (to exclude vma changes,
3240  * but allow concurrent faults), with pte both mapped and locked.
3241  * We return with mmap_lock still held, but pte unmapped and unlocked.
3242  */
3243 static vm_fault_t do_wp_page(struct vm_fault *vmf)
3244         __releases(vmf->ptl)
3245 {
3246         struct vm_area_struct *vma = vmf->vma;
3247
3248         if (userfaultfd_pte_wp(vma, *vmf->pte)) {
3249                 pte_unmap_unlock(vmf->pte, vmf->ptl);
3250                 return handle_userfault(vmf, VM_UFFD_WP);
3251         }
3252
3253         /*
3254          * Userfaultfd write-protect can defer flushes. Ensure the TLB
3255          * is flushed in this case before copying.
3256          */
3257         if (unlikely(userfaultfd_wp(vmf->vma) &&
3258                      mm_tlb_flush_pending(vmf->vma->vm_mm)))
3259                 flush_tlb_page(vmf->vma, vmf->address);
3260
3261         vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
3262         if (!vmf->page) {
3263                 /*
3264                  * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
3265                  * VM_PFNMAP VMA.
3266                  *
3267                  * We should not cow pages in a shared writeable mapping.
3268                  * Just mark the pages writable and/or call ops->pfn_mkwrite.
3269                  */
3270                 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
3271                                      (VM_WRITE|VM_SHARED))
3272                         return wp_pfn_shared(vmf);
3273
3274                 pte_unmap_unlock(vmf->pte, vmf->ptl);
3275                 return wp_page_copy(vmf);
3276         }
3277
3278         /*
3279          * Take out anonymous pages first, anonymous shared vmas are
3280          * not dirty accountable.
3281          */
3282         if (PageAnon(vmf->page)) {
3283                 struct page *page = vmf->page;
3284
3285                 /* PageKsm() doesn't necessarily raise the page refcount */
3286                 if (PageKsm(page) || page_count(page) != 1)
3287                         goto copy;
3288                 if (!trylock_page(page))
3289                         goto copy;
3290                 if (PageKsm(page) || page_mapcount(page) != 1 || page_count(page) != 1) {
3291                         unlock_page(page);
3292                         goto copy;
3293                 }
3294                 /*
3295                  * Ok, we've got the only map reference, and the only
3296                  * page count reference, and the page is locked,
3297                  * it's dark out, and we're wearing sunglasses. Hit it.
3298                  */
3299                 unlock_page(page);
3300                 wp_page_reuse(vmf);
3301                 return VM_FAULT_WRITE;
3302         } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
3303                                         (VM_WRITE|VM_SHARED))) {
3304                 return wp_page_shared(vmf);
3305         }
3306 copy:
3307         /*
3308          * Ok, we need to copy. Oh, well..
3309          */
3310         get_page(vmf->page);
3311
3312         pte_unmap_unlock(vmf->pte, vmf->ptl);
3313         return wp_page_copy(vmf);
3314 }
3315
3316 static void unmap_mapping_range_vma(struct vm_area_struct *vma,
3317                 unsigned long start_addr, unsigned long end_addr,
3318                 struct zap_details *details)
3319 {
3320         zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
3321 }
3322
3323 static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
3324                                             struct zap_details *details)
3325 {
3326         struct vm_area_struct *vma;
3327         pgoff_t vba, vea, zba, zea;
3328
3329         vma_interval_tree_foreach(vma, root,
3330                         details->first_index, details->last_index) {
3331
3332                 vba = vma->vm_pgoff;
3333                 vea = vba + vma_pages(vma) - 1;
3334                 zba = details->first_index;
3335                 if (zba < vba)
3336                         zba = vba;
3337                 zea = details->last_index;
3338                 if (zea > vea)
3339                         zea = vea;
3340
3341                 unmap_mapping_range_vma(vma,
3342                         ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
3343                         ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
3344                                 details);
3345         }
3346 }
3347
3348 /**
3349  * unmap_mapping_page() - Unmap single page from processes.
3350  * @page: The locked page to be unmapped.
3351  *
3352  * Unmap this page from any userspace process which still has it mmaped.
3353  * Typically, for efficiency, the range of nearby pages has already been
3354  * unmapped by unmap_mapping_pages() or unmap_mapping_range().  But once
3355  * truncation or invalidation holds the lock on a page, it may find that
3356  * the page has been remapped again: and then uses unmap_mapping_page()
3357  * to unmap it finally.
3358  */
3359 void unmap_mapping_page(struct page *page)
3360 {
3361         struct address_space *mapping = page->mapping;
3362         struct zap_details details = { };
3363
3364         VM_BUG_ON(!PageLocked(page));
3365         VM_BUG_ON(PageTail(page));
3366
3367         details.check_mapping = mapping;
3368         details.first_index = page->index;
3369         details.last_index = page->index + thp_nr_pages(page) - 1;
3370         details.single_page = page;
3371
3372         i_mmap_lock_write(mapping);
3373         if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
3374                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
3375         i_mmap_unlock_write(mapping);
3376 }
3377
3378 /**
3379  * unmap_mapping_pages() - Unmap pages from processes.
3380  * @mapping: The address space containing pages to be unmapped.
3381  * @start: Index of first page to be unmapped.
3382  * @nr: Number of pages to be unmapped.  0 to unmap to end of file.
3383  * @even_cows: Whether to unmap even private COWed pages.
3384  *
3385  * Unmap the pages in this address space from any userspace process which
3386  * has them mmaped.  Generally, you want to remove COWed pages as well when
3387  * a file is being truncated, but not when invalidating pages from the page
3388  * cache.
3389  */
3390 void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
3391                 pgoff_t nr, bool even_cows)
3392 {
3393         struct zap_details details = { };
3394
3395         details.check_mapping = even_cows ? NULL : mapping;
3396         details.first_index = start;
3397         details.last_index = start + nr - 1;
3398         if (details.last_index < details.first_index)
3399                 details.last_index = ULONG_MAX;
3400
3401         i_mmap_lock_write(mapping);
3402         if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
3403                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
3404         i_mmap_unlock_write(mapping);
3405 }
3406 EXPORT_SYMBOL_GPL(unmap_mapping_pages);
3407
3408 /**
3409  * unmap_mapping_range - unmap the portion of all mmaps in the specified
3410  * address_space corresponding to the specified byte range in the underlying
3411  * file.
3412  *
3413  * @mapping: the address space containing mmaps to be unmapped.
3414  * @holebegin: byte in first page to unmap, relative to the start of
3415  * the underlying file.  This will be rounded down to a PAGE_SIZE
3416  * boundary.  Note that this is different from truncate_pagecache(), which
3417  * must keep the partial page.  In contrast, we must get rid of
3418  * partial pages.
3419  * @holelen: size of prospective hole in bytes.  This will be rounded
3420  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
3421  * end of the file.
3422  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
3423  * but 0 when invalidating pagecache, don't throw away private data.
3424  */
3425 void unmap_mapping_range(struct address_space *mapping,
3426                 loff_t const holebegin, loff_t const holelen, int even_cows)
3427 {
3428         pgoff_t hba = holebegin >> PAGE_SHIFT;
3429         pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
3430
3431         /* Check for overflow. */
3432         if (sizeof(holelen) > sizeof(hlen)) {
3433                 long long holeend =
3434                         (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
3435                 if (holeend & ~(long long)ULONG_MAX)
3436                         hlen = ULONG_MAX - hba + 1;
3437         }
3438
3439         unmap_mapping_pages(mapping, hba, hlen, even_cows);
3440 }
3441 EXPORT_SYMBOL(unmap_mapping_range);
3442
3443 /*
3444  * Restore a potential device exclusive pte to a working pte entry
3445  */
3446 static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf)
3447 {
3448         struct page *page = vmf->page;
3449         struct vm_area_struct *vma = vmf->vma;
3450         struct mmu_notifier_range range;
3451
3452         if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags))
3453                 return VM_FAULT_RETRY;
3454         mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0, vma,
3455                                 vma->vm_mm, vmf->address & PAGE_MASK,
3456                                 (vmf->address & PAGE_MASK) + PAGE_SIZE, NULL);
3457         mmu_notifier_invalidate_range_start(&range);
3458
3459         vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3460                                 &vmf->ptl);
3461         if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
3462                 restore_exclusive_pte(vma, page, vmf->address, vmf->pte);
3463
3464         pte_unmap_unlock(vmf->pte, vmf->ptl);
3465         unlock_page(page);
3466
3467         mmu_notifier_invalidate_range_end(&range);
3468         return 0;
3469 }
3470
3471 /*
3472  * We enter with non-exclusive mmap_lock (to exclude vma changes,
3473  * but allow concurrent faults), and pte mapped but not yet locked.
3474  * We return with pte unmapped and unlocked.
3475  *
3476  * We return with the mmap_lock locked or unlocked in the same cases
3477  * as does filemap_fault().
3478  */
3479 vm_fault_t do_swap_page(struct vm_fault *vmf)
3480 {
3481         struct vm_area_struct *vma = vmf->vma;
3482         struct page *page = NULL, *swapcache;
3483         struct swap_info_struct *si = NULL;
3484         swp_entry_t entry;
3485         pte_t pte;
3486         int locked;
3487         int exclusive = 0;
3488         vm_fault_t ret = 0;
3489         void *shadow = NULL;
3490
3491         if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
3492                 goto out;
3493
3494         entry = pte_to_swp_entry(vmf->orig_pte);
3495         if (unlikely(non_swap_entry(entry))) {
3496                 if (is_migration_entry(entry)) {
3497                         migration_entry_wait(vma->vm_mm, vmf->pmd,
3498                                              vmf->address);
3499                 } else if (is_device_exclusive_entry(entry)) {
3500                         vmf->page = pfn_swap_entry_to_page(entry);
3501                         ret = remove_device_exclusive_entry(vmf);
3502                 } else if (is_device_private_entry(entry)) {
3503                         vmf->page = pfn_swap_entry_to_page(entry);
3504                         ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
3505                 } else if (is_hwpoison_entry(entry)) {
3506                         ret = VM_FAULT_HWPOISON;
3507                 } else {
3508                         print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
3509                         ret = VM_FAULT_SIGBUS;
3510                 }
3511                 goto out;
3512         }
3513
3514         /* Prevent swapoff from happening to us. */
3515         si = get_swap_device(entry);
3516         if (unlikely(!si))
3517                 goto out;
3518
3519         delayacct_set_flag(current, DELAYACCT_PF_SWAPIN);
3520         page = lookup_swap_cache(entry, vma, vmf->address);
3521         swapcache = page;
3522
3523         if (!page) {
3524                 if (data_race(si->flags & SWP_SYNCHRONOUS_IO) &&
3525                     __swap_count(entry) == 1) {
3526                         /* skip swapcache */
3527                         page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
3528                                                         vmf->address);
3529                         if (page) {
3530                                 __SetPageLocked(page);
3531                                 __SetPageSwapBacked(page);
3532
3533                                 if (mem_cgroup_swapin_charge_page(page,
3534                                         vma->vm_mm, GFP_KERNEL, entry)) {
3535                                         ret = VM_FAULT_OOM;
3536                                         goto out_page;
3537                                 }
3538                                 mem_cgroup_swapin_uncharge_swap(entry);
3539
3540                                 shadow = get_shadow_from_swap_cache(entry);
3541                                 if (shadow)
3542                                         workingset_refault(page, shadow);
3543
3544                                 lru_cache_add(page);
3545
3546                                 /* To provide entry to swap_readpage() */
3547                                 set_page_private(page, entry.val);
3548                                 swap_readpage(page, true);
3549                                 set_page_private(page, 0);
3550                         }
3551                 } else {
3552                         page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
3553                                                 vmf);
3554                         swapcache = page;
3555                 }
3556
3557                 if (!page) {
3558                         /*
3559                          * Back out if somebody else faulted in this pte
3560                          * while we released the pte lock.
3561                          */
3562                         vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3563                                         vmf->address, &vmf->ptl);
3564                         if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
3565                                 ret = VM_FAULT_OOM;
3566                         delayacct_clear_flag(current, DELAYACCT_PF_SWAPIN);
3567                         goto unlock;
3568                 }
3569
3570                 /* Had to read the page from swap area: Major fault */
3571                 ret = VM_FAULT_MAJOR;
3572                 count_vm_event(PGMAJFAULT);
3573                 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
3574         } else if (PageHWPoison(page)) {
3575                 /*
3576                  * hwpoisoned dirty swapcache pages are kept for killing
3577                  * owner processes (which may be unknown at hwpoison time)
3578                  */
3579                 ret = VM_FAULT_HWPOISON;
3580                 delayacct_clear_flag(current, DELAYACCT_PF_SWAPIN);
3581                 goto out_release;
3582         }
3583
3584         locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
3585
3586         delayacct_clear_flag(current, DELAYACCT_PF_SWAPIN);
3587         if (!locked) {
3588                 ret |= VM_FAULT_RETRY;
3589                 goto out_release;
3590         }
3591
3592         /*
3593          * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
3594          * release the swapcache from under us.  The page pin, and pte_same
3595          * test below, are not enough to exclude that.  Even if it is still
3596          * swapcache, we need to check that the page's swap has not changed.
3597          */
3598         if (unlikely((!PageSwapCache(page) ||
3599                         page_private(page) != entry.val)) && swapcache)
3600                 goto out_page;
3601
3602         page = ksm_might_need_to_copy(page, vma, vmf->address);
3603         if (unlikely(!page)) {
3604                 ret = VM_FAULT_OOM;
3605                 page = swapcache;
3606                 goto out_page;
3607         }
3608
3609         cgroup_throttle_swaprate(page, GFP_KERNEL);
3610
3611         /*
3612          * Back out if somebody else already faulted in this pte.
3613          */
3614         vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3615                         &vmf->ptl);
3616         if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
3617                 goto out_nomap;
3618
3619         if (unlikely(!PageUptodate(page))) {
3620                 ret = VM_FAULT_SIGBUS;
3621                 goto out_nomap;
3622         }
3623
3624         /*
3625          * The page isn't present yet, go ahead with the fault.
3626          *
3627          * Be careful about the sequence of operations here.
3628          * To get its accounting right, reuse_swap_page() must be called
3629          * while the page is counted on swap but not yet in mapcount i.e.
3630          * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
3631          * must be called after the swap_free(), or it will never succeed.
3632          */
3633
3634         inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3635         dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
3636         pte = mk_pte(page, vma->vm_page_prot);
3637         if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
3638                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
3639                 vmf->flags &= ~FAULT_FLAG_WRITE;
3640                 ret |= VM_FAULT_WRITE;
3641                 exclusive = RMAP_EXCLUSIVE;
3642         }
3643         flush_icache_page(vma, page);
3644         if (pte_swp_soft_dirty(vmf->orig_pte))
3645                 pte = pte_mksoft_dirty(pte);
3646         if (pte_swp_uffd_wp(vmf->orig_pte)) {
3647                 pte = pte_mkuffd_wp(pte);
3648                 pte = pte_wrprotect(pte);
3649         }
3650         set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
3651         arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte);
3652         vmf->orig_pte = pte;
3653
3654         /* ksm created a completely new copy */
3655         if (unlikely(page != swapcache && swapcache)) {
3656                 page_add_new_anon_rmap(page, vma, vmf->address, false);
3657                 lru_cache_add_inactive_or_unevictable(page, vma);
3658         } else {
3659                 do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
3660         }
3661
3662         swap_free(entry);
3663         if (mem_cgroup_swap_full(page) ||
3664             (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
3665                 try_to_free_swap(page);
3666         unlock_page(page);
3667         if (page != swapcache && swapcache) {
3668                 /*
3669                  * Hold the lock to avoid the swap entry to be reused
3670                  * until we take the PT lock for the pte_same() check
3671                  * (to avoid false positives from pte_same). For
3672                  * further safety release the lock after the swap_free
3673                  * so that the swap count won't change under a
3674                  * parallel locked swapcache.
3675                  */
3676                 unlock_page(swapcache);
3677                 put_page(swapcache);
3678         }
3679
3680         if (vmf->flags & FAULT_FLAG_WRITE) {
3681                 ret |= do_wp_page(vmf);
3682                 if (ret & VM_FAULT_ERROR)
3683                         ret &= VM_FAULT_ERROR;
3684                 goto out;
3685         }
3686
3687         /* No need to invalidate - it was non-present before */
3688         update_mmu_cache(vma, vmf->address, vmf->pte);
3689 unlock:
3690         pte_unmap_unlock(vmf->pte, vmf->ptl);
3691 out:
3692         if (si)
3693                 put_swap_device(si);
3694         return ret;
3695 out_nomap:
3696         pte_unmap_unlock(vmf->pte, vmf->ptl);
3697 out_page:
3698         unlock_page(page);
3699 out_release:
3700         put_page(page);
3701         if (page != swapcache && swapcache) {
3702                 unlock_page(swapcache);
3703                 put_page(swapcache);
3704         }
3705         if (si)
3706                 put_swap_device(si);
3707         return ret;
3708 }
3709
3710 /*
3711  * We enter with non-exclusive mmap_lock (to exclude vma changes,
3712  * but allow concurrent faults), and pte mapped but not yet locked.
3713  * We return with mmap_lock still held, but pte unmapped and unlocked.
3714  */
3715 static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
3716 {
3717         struct vm_area_struct *vma = vmf->vma;
3718         struct page *page;
3719         vm_fault_t ret = 0;
3720         pte_t entry;
3721
3722         /* File mapping without ->vm_ops ? */
3723         if (vma->vm_flags & VM_SHARED)
3724                 return VM_FAULT_SIGBUS;
3725
3726         /*
3727          * Use pte_alloc() instead of pte_alloc_map().  We can't run
3728          * pte_offset_map() on pmds where a huge pmd might be created
3729          * from a different thread.
3730          *
3731          * pte_alloc_map() is safe to use under mmap_write_lock(mm) or when
3732          * parallel threads are excluded by other means.
3733          *
3734          * Here we only have mmap_read_lock(mm).
3735          */
3736         if (pte_alloc(vma->vm_mm, vmf->pmd))
3737                 return VM_FAULT_OOM;
3738
3739         /* See comment in handle_pte_fault() */
3740         if (unlikely(pmd_trans_unstable(vmf->pmd)))
3741                 return 0;
3742
3743         /* Use the zero-page for reads */
3744         if (!(vmf->flags & FAULT_FLAG_WRITE) &&
3745                         !mm_forbids_zeropage(vma->vm_mm)) {
3746                 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
3747                                                 vma->vm_page_prot));
3748                 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3749                                 vmf->address, &vmf->ptl);
3750                 if (!pte_none(*vmf->pte)) {
3751                         update_mmu_tlb(vma, vmf->address, vmf->pte);
3752                         goto unlock;
3753                 }
3754                 ret = check_stable_address_space(vma->vm_mm);
3755                 if (ret)
3756                         goto unlock;
3757                 /* Deliver the page fault to userland, check inside PT lock */
3758                 if (userfaultfd_missing(vma)) {
3759                         pte_unmap_unlock(vmf->pte, vmf->ptl);
3760                         return handle_userfault(vmf, VM_UFFD_MISSING);
3761                 }
3762                 goto setpte;
3763         }
3764
3765         /* Allocate our own private page. */
3766         if (unlikely(anon_vma_prepare(vma)))
3767                 goto oom;
3768         page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
3769         if (!page)
3770                 goto oom;
3771
3772         if (mem_cgroup_charge(page, vma->vm_mm, GFP_KERNEL))
3773                 goto oom_free_page;
3774         cgroup_throttle_swaprate(page, GFP_KERNEL);
3775
3776         /*
3777          * The memory barrier inside __SetPageUptodate makes sure that
3778          * preceding stores to the page contents become visible before
3779          * the set_pte_at() write.
3780          */
3781         __SetPageUptodate(page);
3782
3783         entry = mk_pte(page, vma->vm_page_prot);
3784         entry = pte_sw_mkyoung(entry);
3785         if (vma->vm_flags & VM_WRITE)
3786                 entry = pte_mkwrite(pte_mkdirty(entry));
3787
3788         vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3789                         &vmf->ptl);
3790         if (!pte_none(*vmf->pte)) {
3791                 update_mmu_cache(vma, vmf->address, vmf->pte);
3792                 goto release;
3793         }
3794
3795         ret = check_stable_address_space(vma->vm_mm);
3796         if (ret)
3797                 goto release;
3798
3799         /* Deliver the page fault to userland, check inside PT lock */
3800         if (userfaultfd_missing(vma)) {
3801                 pte_unmap_unlock(vmf->pte, vmf->ptl);
3802                 put_page(page);
3803                 return handle_userfault(vmf, VM_UFFD_MISSING);
3804         }
3805
3806         inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3807         page_add_new_anon_rmap(page, vma, vmf->address, false);
3808         lru_cache_add_inactive_or_unevictable(page, vma);
3809 setpte:
3810         set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3811
3812         /* No need to invalidate - it was non-present before */
3813         update_mmu_cache(vma, vmf->address, vmf->pte);
3814 unlock:
3815         pte_unmap_unlock(vmf->pte, vmf->ptl);
3816         return ret;
3817 release:
3818         put_page(page);
3819         goto unlock;
3820 oom_free_page:
3821         put_page(page);
3822 oom:
3823         return VM_FAULT_OOM;
3824 }
3825
3826 /*
3827  * The mmap_lock must have been held on entry, and may have been
3828  * released depending on flags and vma->vm_ops->fault() return value.
3829  * See filemap_fault() and __lock_page_retry().
3830  */
3831 static vm_fault_t __do_fault(struct vm_fault *vmf)
3832 {
3833         struct vm_area_struct *vma = vmf->vma;
3834         vm_fault_t ret;
3835
3836         /*
3837          * Preallocate pte before we take page_lock because this might lead to
3838          * deadlocks for memcg reclaim which waits for pages under writeback:
3839          *                              lock_page(A)
3840          *                              SetPageWriteback(A)
3841          *                              unlock_page(A)
3842          * lock_page(B)
3843          *                              lock_page(B)
3844          * pte_alloc_one
3845          *   shrink_page_list
3846          *     wait_on_page_writeback(A)
3847          *                              SetPageWriteback(B)
3848          *                              unlock_page(B)
3849          *                              # flush A, B to clear the writeback
3850          */
3851         if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) {
3852                 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
3853                 if (!vmf->prealloc_pte)
3854                         return VM_FAULT_OOM;
3855                 smp_wmb(); /* See comment in __pte_alloc() */
3856         }
3857
3858         ret = vma->vm_ops->fault(vmf);
3859         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
3860                             VM_FAULT_DONE_COW)))
3861                 return ret;
3862
3863         if (unlikely(PageHWPoison(vmf->page))) {
3864                 if (ret & VM_FAULT_LOCKED)
3865                         unlock_page(vmf->page);
3866                 put_page(vmf->page);
3867                 vmf->page = NULL;
3868                 return VM_FAULT_HWPOISON;
3869         }
3870
3871         if (unlikely(!(ret & VM_FAULT_LOCKED)))
3872                 lock_page(vmf->page);
3873         else
3874                 VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
3875
3876         return ret;
3877 }
3878
3879 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3880 static void deposit_prealloc_pte(struct vm_fault *vmf)
3881 {
3882         struct vm_area_struct *vma = vmf->vma;
3883
3884         pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3885         /*
3886          * We are going to consume the prealloc table,
3887          * count that as nr_ptes.
3888          */
3889         mm_inc_nr_ptes(vma->vm_mm);
3890         vmf->prealloc_pte = NULL;
3891 }
3892
3893 vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
3894 {
3895         struct vm_area_struct *vma = vmf->vma;
3896         bool write = vmf->flags & FAULT_FLAG_WRITE;
3897         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
3898         pmd_t entry;
3899         int i;
3900         vm_fault_t ret = VM_FAULT_FALLBACK;
3901
3902         if (!transhuge_vma_suitable(vma, haddr))
3903                 return ret;
3904
3905         page = compound_head(page);
3906         if (compound_order(page) != HPAGE_PMD_ORDER)
3907                 return ret;
3908
3909         /*
3910          * Archs like ppc64 need additional space to store information
3911          * related to pte entry. Use the preallocated table for that.
3912          */
3913         if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
3914                 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
3915                 if (!vmf->prealloc_pte)
3916                         return VM_FAULT_OOM;
3917                 smp_wmb(); /* See comment in __pte_alloc() */
3918         }
3919
3920         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3921         if (unlikely(!pmd_none(*vmf->pmd)))
3922                 goto out;
3923
3924         for (i = 0; i < HPAGE_PMD_NR; i++)
3925                 flush_icache_page(vma, page + i);
3926
3927         entry = mk_huge_pmd(page, vma->vm_page_prot);
3928         if (write)
3929                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
3930
3931         add_mm_counter(vma->vm_mm, mm_counter_file(page), HPAGE_PMD_NR);
3932         page_add_file_rmap(page, true);
3933         /*
3934          * deposit and withdraw with pmd lock held
3935          */
3936         if (arch_needs_pgtable_deposit())
3937                 deposit_prealloc_pte(vmf);
3938
3939         set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
3940
3941         update_mmu_cache_pmd(vma, haddr, vmf->pmd);
3942
3943         /* fault is handled */
3944         ret = 0;
3945         count_vm_event(THP_FILE_MAPPED);
3946 out:
3947         spin_unlock(vmf->ptl);
3948         return ret;
3949 }
3950 #else
3951 vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
3952 {
3953         return VM_FAULT_FALLBACK;
3954 }
3955 #endif
3956
3957 void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr)
3958 {
3959         struct vm_area_struct *vma = vmf->vma;
3960         bool write = vmf->flags & FAULT_FLAG_WRITE;
3961         bool prefault = vmf->address != addr;
3962         pte_t entry;
3963
3964         flush_icache_page(vma, page);
3965         entry = mk_pte(page, vma->vm_page_prot);
3966
3967         if (prefault && arch_wants_old_prefaulted_pte())
3968                 entry = pte_mkold(entry);
3969         else
3970                 entry = pte_sw_mkyoung(entry);
3971
3972         if (write)
3973                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3974         /* copy-on-write page */
3975         if (write && !(vma->vm_flags & VM_SHARED)) {
3976                 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3977                 page_add_new_anon_rmap(page, vma, addr, false);
3978                 lru_cache_add_inactive_or_unevictable(page, vma);
3979         } else {
3980                 inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
3981                 page_add_file_rmap(page, false);
3982         }
3983         set_pte_at(vma->vm_mm, addr, vmf->pte, entry);
3984 }
3985
3986 /**
3987  * finish_fault - finish page fault once we have prepared the page to fault
3988  *
3989  * @vmf: structure describing the fault
3990  *
3991  * This function handles all that is needed to finish a page fault once the
3992  * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
3993  * given page, adds reverse page mapping, handles memcg charges and LRU
3994  * addition.
3995  *
3996  * The function expects the page to be locked and on success it consumes a
3997  * reference of a page being mapped (for the PTE which maps it).
3998  *
3999  * Return: %0 on success, %VM_FAULT_ code in case of error.
4000  */
4001 vm_fault_t finish_fault(struct vm_fault *vmf)
4002 {
4003         struct vm_area_struct *vma = vmf->vma;
4004         struct page *page;
4005         vm_fault_t ret;
4006
4007         /* Did we COW the page? */
4008         if ((vmf->flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
4009                 page = vmf->cow_page;
4010         else
4011                 page = vmf->page;
4012
4013         /*
4014          * check even for read faults because we might have lost our CoWed
4015          * page
4016          */
4017         if (!(vma->vm_flags & VM_SHARED)) {
4018                 ret = check_stable_address_space(vma->vm_mm);
4019                 if (ret)
4020                         return ret;
4021         }
4022
4023         if (pmd_none(*vmf->pmd)) {
4024                 if (PageTransCompound(page)) {
4025                         ret = do_set_pmd(vmf, page);
4026                         if (ret != VM_FAULT_FALLBACK)
4027                                 return ret;
4028                 }
4029
4030                 if (vmf->prealloc_pte) {
4031                         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
4032                         if (likely(pmd_none(*vmf->pmd))) {
4033                                 mm_inc_nr_ptes(vma->vm_mm);
4034                                 pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
4035                                 vmf->prealloc_pte = NULL;
4036                         }
4037                         spin_unlock(vmf->ptl);
4038                 } else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd))) {
4039                         return VM_FAULT_OOM;
4040                 }
4041         }
4042
4043         /* See comment in handle_pte_fault() */
4044         if (pmd_devmap_trans_unstable(vmf->pmd))
4045                 return 0;
4046
4047         vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4048                                       vmf->address, &vmf->ptl);
4049         ret = 0;
4050         /* Re-check under ptl */
4051         if (likely(pte_none(*vmf->pte)))
4052                 do_set_pte(vmf, page, vmf->address);
4053         else
4054                 ret = VM_FAULT_NOPAGE;
4055
4056         update_mmu_tlb(vma, vmf->address, vmf->pte);
4057         pte_unmap_unlock(vmf->pte, vmf->ptl);
4058         return ret;
4059 }
4060
4061 static unsigned long fault_around_bytes __read_mostly =
4062         rounddown_pow_of_two(65536);
4063
4064 #ifdef CONFIG_DEBUG_FS
4065 static int fault_around_bytes_get(void *data, u64 *val)
4066 {
4067         *val = fault_around_bytes;
4068         return 0;
4069 }
4070
4071 /*
4072  * fault_around_bytes must be rounded down to the nearest page order as it's
4073  * what do_fault_around() expects to see.
4074  */
4075 static int fault_around_bytes_set(void *data, u64 val)
4076 {
4077         if (val / PAGE_SIZE > PTRS_PER_PTE)
4078                 return -EINVAL;
4079         if (val > PAGE_SIZE)
4080                 fault_around_bytes = rounddown_pow_of_two(val);
4081         else
4082                 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
4083         return 0;
4084 }
4085 DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
4086                 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
4087
4088 static int __init fault_around_debugfs(void)
4089 {
4090         debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
4091                                    &fault_around_bytes_fops);
4092         return 0;
4093 }
4094 late_initcall(fault_around_debugfs);
4095 #endif
4096
4097 /*
4098  * do_fault_around() tries to map few pages around the fault address. The hope
4099  * is that the pages will be needed soon and this will lower the number of
4100  * faults to handle.
4101  *
4102  * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
4103  * not ready to be mapped: not up-to-date, locked, etc.
4104  *
4105  * This function is called with the page table lock taken. In the split ptlock
4106  * case the page table lock only protects only those entries which belong to
4107  * the page table corresponding to the fault address.
4108  *
4109  * This function doesn't cross the VMA boundaries, in order to call map_pages()
4110  * only once.
4111  *
4112  * fault_around_bytes defines how many bytes we'll try to map.
4113  * do_fault_around() expects it to be set to a power of two less than or equal
4114  * to PTRS_PER_PTE.
4115  *
4116  * The virtual address of the area that we map is naturally aligned to
4117  * fault_around_bytes rounded down to the machine page size
4118  * (and therefore to page order).  This way it's easier to guarantee
4119  * that we don't cross page table boundaries.
4120  */
4121 static vm_fault_t do_fault_around(struct vm_fault *vmf)
4122 {
4123         unsigned long address = vmf->address, nr_pages, mask;
4124         pgoff_t start_pgoff = vmf->pgoff;
4125         pgoff_t end_pgoff;
4126         int off;
4127
4128         nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
4129         mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
4130
4131         address = max(address & mask, vmf->vma->vm_start);
4132         off = ((vmf->address - address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
4133         start_pgoff -= off;
4134
4135         /*
4136          *  end_pgoff is either the end of the page table, the end of
4137          *  the vma or nr_pages from start_pgoff, depending what is nearest.
4138          */
4139         end_pgoff = start_pgoff -
4140                 ((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
4141                 PTRS_PER_PTE - 1;
4142         end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
4143                         start_pgoff + nr_pages - 1);
4144
4145         if (pmd_none(*vmf->pmd)) {
4146                 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm);
4147                 if (!vmf->prealloc_pte)
4148                         return VM_FAULT_OOM;
4149                 smp_wmb(); /* See comment in __pte_alloc() */
4150         }
4151
4152         return vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
4153 }
4154
4155 static vm_fault_t do_read_fault(struct vm_fault *vmf)
4156 {
4157         struct vm_area_struct *vma = vmf->vma;
4158         vm_fault_t ret = 0;
4159
4160         /*
4161          * Let's call ->map_pages() first and use ->fault() as fallback
4162          * if page by the offset is not ready to be mapped (cold cache or
4163          * something).
4164          */
4165         if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
4166                 if (likely(!userfaultfd_minor(vmf->vma))) {
4167                         ret = do_fault_around(vmf);
4168                         if (ret)
4169                                 return ret;
4170                 }
4171         }
4172
4173         ret = __do_fault(vmf);
4174         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4175                 return ret;
4176
4177         ret |= finish_fault(vmf);
4178         unlock_page(vmf->page);
4179         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4180                 put_page(vmf->page);
4181         return ret;
4182 }
4183
4184 static vm_fault_t do_cow_fault(struct vm_fault *vmf)
4185 {
4186         struct vm_area_struct *vma = vmf->vma;
4187         vm_fault_t ret;
4188
4189         if (unlikely(anon_vma_prepare(vma)))
4190                 return VM_FAULT_OOM;
4191
4192         vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
4193         if (!vmf->cow_page)
4194                 return VM_FAULT_OOM;
4195
4196         if (mem_cgroup_charge(vmf->cow_page, vma->vm_mm, GFP_KERNEL)) {
4197                 put_page(vmf->cow_page);
4198                 return VM_FAULT_OOM;
4199         }
4200         cgroup_throttle_swaprate(vmf->cow_page, GFP_KERNEL);
4201
4202         ret = __do_fault(vmf);
4203         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4204                 goto uncharge_out;
4205         if (ret & VM_FAULT_DONE_COW)
4206                 return ret;
4207
4208         copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
4209         __SetPageUptodate(vmf->cow_page);
4210
4211         ret |= finish_fault(vmf);
4212         unlock_page(vmf->page);
4213         put_page(vmf->page);
4214         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4215                 goto uncharge_out;
4216         return ret;
4217 uncharge_out:
4218         put_page(vmf->cow_page);
4219         return ret;
4220 }
4221
4222 static vm_fault_t do_shared_fault(struct vm_fault *vmf)
4223 {
4224         struct vm_area_struct *vma = vmf->vma;
4225         vm_fault_t ret, tmp;
4226
4227         ret = __do_fault(vmf);
4228         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4229                 return ret;
4230
4231         /*
4232          * Check if the backing address space wants to know that the page is
4233          * about to become writable
4234          */
4235         if (vma->vm_ops->page_mkwrite) {
4236                 unlock_page(vmf->page);
4237                 tmp = do_page_mkwrite(vmf);
4238                 if (unlikely(!tmp ||
4239                                 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
4240                         put_page(vmf->page);
4241                         return tmp;
4242                 }
4243         }
4244
4245         ret |= finish_fault(vmf);
4246         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
4247                                         VM_FAULT_RETRY))) {
4248                 unlock_page(vmf->page);
4249                 put_page(vmf->page);
4250                 return ret;
4251         }
4252
4253         ret |= fault_dirty_shared_page(vmf);
4254         return ret;
4255 }
4256
4257 /*
4258  * We enter with non-exclusive mmap_lock (to exclude vma changes,
4259  * but allow concurrent faults).
4260  * The mmap_lock may have been released depending on flags and our
4261  * return value.  See filemap_fault() and __lock_page_or_retry().
4262  * If mmap_lock is released, vma may become invalid (for example
4263  * by other thread calling munmap()).
4264  */
4265 static vm_fault_t do_fault(struct vm_fault *vmf)
4266 {
4267         struct vm_area_struct *vma = vmf->vma;
4268         struct mm_struct *vm_mm = vma->vm_mm;
4269         vm_fault_t ret;
4270
4271         /*
4272          * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND
4273          */
4274         if (!vma->vm_ops->fault) {
4275                 /*
4276                  * If we find a migration pmd entry or a none pmd entry, which
4277                  * should never happen, return SIGBUS
4278                  */
4279                 if (unlikely(!pmd_present(*vmf->pmd)))
4280                         ret = VM_FAULT_SIGBUS;
4281                 else {
4282                         vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm,
4283                                                        vmf->pmd,
4284                                                        vmf->address,
4285                                                        &vmf->ptl);
4286                         /*
4287                          * Make sure this is not a temporary clearing of pte
4288                          * by holding ptl and checking again. A R/M/W update
4289                          * of pte involves: take ptl, clearing the pte so that
4290                          * we don't have concurrent modification by hardware
4291                          * followed by an update.
4292                          */
4293                         if (unlikely(pte_none(*vmf->pte)))
4294                                 ret = VM_FAULT_SIGBUS;
4295                         else
4296                                 ret = VM_FAULT_NOPAGE;
4297
4298                         pte_unmap_unlock(vmf->pte, vmf->ptl);
4299                 }
4300         } else if (!(vmf->flags & FAULT_FLAG_WRITE))
4301                 ret = do_read_fault(vmf);
4302         else if (!(vma->vm_flags & VM_SHARED))
4303                 ret = do_cow_fault(vmf);
4304         else
4305                 ret = do_shared_fault(vmf);
4306
4307         /* preallocated pagetable is unused: free it */
4308         if (vmf->prealloc_pte) {
4309                 pte_free(vm_mm, vmf->prealloc_pte);
4310                 vmf->prealloc_pte = NULL;
4311         }
4312         return ret;
4313 }
4314
4315 int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
4316                       unsigned long addr, int page_nid, int *flags)
4317 {
4318         get_page(page);
4319
4320         count_vm_numa_event(NUMA_HINT_FAULTS);
4321         if (page_nid == numa_node_id()) {
4322                 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
4323                 *flags |= TNF_FAULT_LOCAL;
4324         }
4325
4326         return mpol_misplaced(page, vma, addr);
4327 }
4328
4329 static vm_fault_t do_numa_page(struct vm_fault *vmf)
4330 {
4331         struct vm_area_struct *vma = vmf->vma;
4332         struct page *page = NULL;
4333         int page_nid = NUMA_NO_NODE;
4334         int last_cpupid;
4335         int target_nid;
4336         pte_t pte, old_pte;
4337         bool was_writable = pte_savedwrite(vmf->orig_pte);
4338         int flags = 0;
4339
4340         /*
4341          * The "pte" at this point cannot be used safely without
4342          * validation through pte_unmap_same(). It's of NUMA type but
4343          * the pfn may be screwed if the read is non atomic.
4344          */
4345         vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
4346         spin_lock(vmf->ptl);
4347         if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
4348                 pte_unmap_unlock(vmf->pte, vmf->ptl);
4349                 goto out;
4350         }
4351
4352         /* Get the normal PTE  */
4353         old_pte = ptep_get(vmf->pte);
4354         pte = pte_modify(old_pte, vma->vm_page_prot);
4355
4356         page = vm_normal_page(vma, vmf->address, pte);
4357         if (!page)
4358                 goto out_map;
4359
4360         /* TODO: handle PTE-mapped THP */
4361         if (PageCompound(page))
4362                 goto out_map;
4363
4364         /*
4365          * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
4366          * much anyway since they can be in shared cache state. This misses
4367          * the case where a mapping is writable but the process never writes
4368          * to it but pte_write gets cleared during protection updates and
4369          * pte_dirty has unpredictable behaviour between PTE scan updates,
4370          * background writeback, dirty balancing and application behaviour.
4371          */
4372         if (!was_writable)
4373                 flags |= TNF_NO_GROUP;
4374
4375         /*
4376          * Flag if the page is shared between multiple address spaces. This
4377          * is later used when determining whether to group tasks together
4378          */
4379         if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
4380                 flags |= TNF_SHARED;
4381
4382         last_cpupid = page_cpupid_last(page);
4383         page_nid = page_to_nid(page);
4384         target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
4385                         &flags);
4386         if (target_nid == NUMA_NO_NODE) {
4387                 put_page(page);
4388                 goto out_map;
4389         }
4390         pte_unmap_unlock(vmf->pte, vmf->ptl);
4391
4392         /* Migrate to the requested node */
4393         if (migrate_misplaced_page(page, vma, target_nid)) {
4394                 page_nid = target_nid;
4395                 flags |= TNF_MIGRATED;
4396         } else {
4397                 flags |= TNF_MIGRATE_FAIL;
4398                 vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
4399                 spin_lock(vmf->ptl);
4400                 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
4401                         pte_unmap_unlock(vmf->pte, vmf->ptl);
4402                         goto out;
4403                 }
4404                 goto out_map;
4405         }
4406
4407 out:
4408         if (page_nid != NUMA_NO_NODE)
4409                 task_numa_fault(last_cpupid, page_nid, 1, flags);
4410         return 0;
4411 out_map:
4412         /*
4413          * Make it present again, depending on how arch implements
4414          * non-accessible ptes, some can allow access by kernel mode.
4415          */
4416         old_pte = ptep_modify_prot_start(vma, vmf->address, vmf->pte);
4417         pte = pte_modify(old_pte, vma->vm_page_prot);
4418         pte = pte_mkyoung(pte);
4419         if (was_writable)
4420                 pte = pte_mkwrite(pte);
4421         ptep_modify_prot_commit(vma, vmf->address, vmf->pte, old_pte, pte);
4422         update_mmu_cache(vma, vmf->address, vmf->pte);
4423         pte_unmap_unlock(vmf->pte, vmf->ptl);
4424         goto out;
4425 }
4426
4427 static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf)
4428 {
4429         if (vma_is_anonymous(vmf->vma))
4430                 return do_huge_pmd_anonymous_page(vmf);
4431         if (vmf->vma->vm_ops->huge_fault)
4432                 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
4433         return VM_FAULT_FALLBACK;
4434 }
4435
4436 /* `inline' is required to avoid gcc 4.1.2 build error */
4437 static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf)
4438 {
4439         if (vma_is_anonymous(vmf->vma)) {
4440                 if (userfaultfd_huge_pmd_wp(vmf->vma, vmf->orig_pmd))
4441                         return handle_userfault(vmf, VM_UFFD_WP);
4442                 return do_huge_pmd_wp_page(vmf);
4443         }
4444         if (vmf->vma->vm_ops->huge_fault) {
4445                 vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
4446
4447                 if (!(ret & VM_FAULT_FALLBACK))
4448                         return ret;
4449         }
4450
4451         /* COW or write-notify handled on pte level: split pmd. */
4452         __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
4453
4454         return VM_FAULT_FALLBACK;
4455 }
4456
4457 static vm_fault_t create_huge_pud(struct vm_fault *vmf)
4458 {
4459 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) &&                     \
4460         defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
4461         /* No support for anonymous transparent PUD pages yet */
4462         if (vma_is_anonymous(vmf->vma))
4463                 goto split;
4464         if (vmf->vma->vm_ops->huge_fault) {
4465                 vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
4466
4467                 if (!(ret & VM_FAULT_FALLBACK))
4468                         return ret;
4469         }
4470 split:
4471         /* COW or write-notify not handled on PUD level: split pud.*/
4472         __split_huge_pud(vmf->vma, vmf->pud, vmf->address);
4473 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
4474         return VM_FAULT_FALLBACK;
4475 }
4476
4477 static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
4478 {
4479 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
4480         /* No support for anonymous transparent PUD pages yet */
4481         if (vma_is_anonymous(vmf->vma))
4482                 return VM_FAULT_FALLBACK;
4483         if (vmf->vma->vm_ops->huge_fault)
4484                 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
4485 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
4486         return VM_FAULT_FALLBACK;
4487 }
4488
4489 /*
4490  * These routines also need to handle stuff like marking pages dirty
4491  * and/or accessed for architectures that don't do it in hardware (most
4492  * RISC architectures).  The early dirtying is also good on the i386.
4493  *
4494  * There is also a hook called "update_mmu_cache()" that architectures
4495  * with external mmu caches can use to update those (ie the Sparc or
4496  * PowerPC hashed page tables that act as extended TLBs).
4497  *
4498  * We enter with non-exclusive mmap_lock (to exclude vma changes, but allow
4499  * concurrent faults).
4500  *
4501  * The mmap_lock may have been released depending on flags and our return value.
4502  * See filemap_fault() and __lock_page_or_retry().
4503  */
4504 static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
4505 {
4506         pte_t entry;
4507
4508         if (unlikely(pmd_none(*vmf->pmd))) {
4509                 /*
4510                  * Leave __pte_alloc() until later: because vm_ops->fault may
4511                  * want to allocate huge page, and if we expose page table
4512                  * for an instant, it will be difficult to retract from
4513                  * concurrent faults and from rmap lookups.
4514                  */
4515                 vmf->pte = NULL;
4516         } else {
4517                 /*
4518                  * If a huge pmd materialized under us just retry later.  Use
4519                  * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead
4520                  * of pmd_trans_huge() to ensure the pmd didn't become
4521                  * pmd_trans_huge under us and then back to pmd_none, as a
4522                  * result of MADV_DONTNEED running immediately after a huge pmd
4523                  * fault in a different thread of this mm, in turn leading to a
4524                  * misleading pmd_trans_huge() retval. All we have to ensure is
4525                  * that it is a regular pmd that we can walk with
4526                  * pte_offset_map() and we can do that through an atomic read
4527                  * in C, which is what pmd_trans_unstable() provides.
4528                  */
4529                 if (pmd_devmap_trans_unstable(vmf->pmd))
4530                         return 0;
4531                 /*
4532                  * A regular pmd is established and it can't morph into a huge
4533                  * pmd from under us anymore at this point because we hold the
4534                  * mmap_lock read mode and khugepaged takes it in write mode.
4535                  * So now it's safe to run pte_offset_map().
4536                  */
4537                 vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
4538                 vmf->orig_pte = *vmf->pte;
4539
4540                 /*
4541                  * some architectures can have larger ptes than wordsize,
4542                  * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
4543                  * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic
4544                  * accesses.  The code below just needs a consistent view
4545                  * for the ifs and we later double check anyway with the
4546                  * ptl lock held. So here a barrier will do.
4547                  */
4548                 barrier();
4549                 if (pte_none(vmf->orig_pte)) {
4550                         pte_unmap(vmf->pte);
4551                         vmf->pte = NULL;
4552                 }
4553         }
4554
4555         if (!vmf->pte) {
4556                 if (vma_is_anonymous(vmf->vma))
4557                         return do_anonymous_page(vmf);
4558                 else
4559                         return do_fault(vmf);
4560         }
4561
4562         if (!pte_present(vmf->orig_pte))
4563                 return do_swap_page(vmf);
4564
4565         if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
4566                 return do_numa_page(vmf);
4567
4568         vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
4569         spin_lock(vmf->ptl);
4570         entry = vmf->orig_pte;
4571         if (unlikely(!pte_same(*vmf->pte, entry))) {
4572                 update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
4573                 goto unlock;
4574         }
4575         if (vmf->flags & FAULT_FLAG_WRITE) {
4576                 if (!pte_write(entry))
4577                         return do_wp_page(vmf);
4578                 entry = pte_mkdirty(entry);
4579         }
4580         entry = pte_mkyoung(entry);
4581         if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
4582                                 vmf->flags & FAULT_FLAG_WRITE)) {
4583                 update_mmu_cache(vmf->vma, vmf->address, vmf->pte);
4584         } else {
4585                 /* Skip spurious TLB flush for retried page fault */
4586                 if (vmf->flags & FAULT_FLAG_TRIED)
4587                         goto unlock;
4588                 /*
4589                  * This is needed only for protection faults but the arch code
4590                  * is not yet telling us if this is a protection fault or not.
4591                  * This still avoids useless tlb flushes for .text page faults
4592                  * with threads.
4593                  */
4594                 if (vmf->flags & FAULT_FLAG_WRITE)
4595                         flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
4596         }
4597 unlock:
4598         pte_unmap_unlock(vmf->pte, vmf->ptl);
4599         return 0;
4600 }
4601
4602 /*
4603  * By the time we get here, we already hold the mm semaphore
4604  *
4605  * The mmap_lock may have been released depending on flags and our
4606  * return value.  See filemap_fault() and __lock_page_or_retry().
4607  */
4608 static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
4609                 unsigned long address, unsigned int flags)
4610 {
4611         struct vm_fault vmf = {
4612                 .vma = vma,
4613                 .address = address & PAGE_MASK,
4614                 .flags = flags,
4615                 .pgoff = linear_page_index(vma, address),
4616                 .gfp_mask = __get_fault_gfp_mask(vma),
4617         };
4618         unsigned int dirty = flags & FAULT_FLAG_WRITE;
4619         struct mm_struct *mm = vma->vm_mm;
4620         pgd_t *pgd;
4621         p4d_t *p4d;
4622         vm_fault_t ret;
4623
4624         pgd = pgd_offset(mm, address);
4625         p4d = p4d_alloc(mm, pgd, address);
4626         if (!p4d)
4627                 return VM_FAULT_OOM;
4628
4629         vmf.pud = pud_alloc(mm, p4d, address);
4630         if (!vmf.pud)
4631                 return VM_FAULT_OOM;
4632 retry_pud:
4633         if (pud_none(*vmf.pud) && __transparent_hugepage_enabled(vma)) {
4634                 ret = create_huge_pud(&vmf);
4635                 if (!(ret & VM_FAULT_FALLBACK))
4636                         return ret;
4637         } else {
4638                 pud_t orig_pud = *vmf.pud;
4639
4640                 barrier();
4641                 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
4642
4643                         /* NUMA case for anonymous PUDs would go here */
4644
4645                         if (dirty && !pud_write(orig_pud)) {
4646                                 ret = wp_huge_pud(&vmf, orig_pud);
4647                                 if (!(ret & VM_FAULT_FALLBACK))
4648                                         return ret;
4649                         } else {
4650                                 huge_pud_set_accessed(&vmf, orig_pud);
4651                                 return 0;
4652                         }
4653                 }
4654         }
4655
4656         vmf.pmd = pmd_alloc(mm, vmf.pud, address);
4657         if (!vmf.pmd)
4658                 return VM_FAULT_OOM;
4659
4660         /* Huge pud page fault raced with pmd_alloc? */
4661         if (pud_trans_unstable(vmf.pud))
4662                 goto retry_pud;
4663
4664         if (pmd_none(*vmf.pmd) && __transparent_hugepage_enabled(vma)) {
4665                 ret = create_huge_pmd(&vmf);
4666                 if (!(ret & VM_FAULT_FALLBACK))
4667                         return ret;
4668         } else {
4669                 vmf.orig_pmd = *vmf.pmd;
4670
4671                 barrier();
4672                 if (unlikely(is_swap_pmd(vmf.orig_pmd))) {
4673                         VM_BUG_ON(thp_migration_supported() &&
4674                                           !is_pmd_migration_entry(vmf.orig_pmd));
4675                         if (is_pmd_migration_entry(vmf.orig_pmd))
4676                                 pmd_migration_entry_wait(mm, vmf.pmd);
4677                         return 0;
4678                 }
4679                 if (pmd_trans_huge(vmf.orig_pmd) || pmd_devmap(vmf.orig_pmd)) {
4680                         if (pmd_protnone(vmf.orig_pmd) && vma_is_accessible(vma))
4681                                 return do_huge_pmd_numa_page(&vmf);
4682
4683                         if (dirty && !pmd_write(vmf.orig_pmd)) {
4684                                 ret = wp_huge_pmd(&vmf);
4685                                 if (!(ret & VM_FAULT_FALLBACK))
4686                                         return ret;
4687                         } else {
4688                                 huge_pmd_set_accessed(&vmf);
4689                                 return 0;
4690                         }
4691                 }
4692         }
4693
4694         return handle_pte_fault(&vmf);
4695 }
4696
4697 /**
4698  * mm_account_fault - Do page fault accounting
4699  *
4700  * @regs: the pt_regs struct pointer.  When set to NULL, will skip accounting
4701  *        of perf event counters, but we'll still do the per-task accounting to
4702  *        the task who triggered this page fault.
4703  * @address: the faulted address.
4704  * @flags: the fault flags.
4705  * @ret: the fault retcode.
4706  *
4707  * This will take care of most of the page fault accounting.  Meanwhile, it
4708  * will also include the PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN] perf counter
4709  * updates.  However, note that the handling of PERF_COUNT_SW_PAGE_FAULTS should
4710  * still be in per-arch page fault handlers at the entry of page fault.
4711  */
4712 static inline void mm_account_fault(struct pt_regs *regs,
4713                                     unsigned long address, unsigned int flags,
4714                                     vm_fault_t ret)
4715 {
4716         bool major;
4717
4718         /*
4719          * We don't do accounting for some specific faults:
4720          *
4721          * - Unsuccessful faults (e.g. when the address wasn't valid).  That
4722          *   includes arch_vma_access_permitted() failing before reaching here.
4723          *   So this is not a "this many hardware page faults" counter.  We
4724          *   should use the hw profiling for that.
4725          *
4726          * - Incomplete faults (VM_FAULT_RETRY).  They will only be counted
4727          *   once they're completed.
4728          */
4729         if (ret & (VM_FAULT_ERROR | VM_FAULT_RETRY))
4730                 return;
4731
4732         /*
4733          * We define the fault as a major fault when the final successful fault
4734          * is VM_FAULT_MAJOR, or if it retried (which implies that we couldn't
4735          * handle it immediately previously).
4736          */
4737         major = (ret & VM_FAULT_MAJOR) || (flags & FAULT_FLAG_TRIED);
4738
4739         if (major)
4740                 current->maj_flt++;
4741         else
4742                 current->min_flt++;
4743
4744         /*
4745          * If the fault is done for GUP, regs will be NULL.  We only do the
4746          * accounting for the per thread fault counters who triggered the
4747          * fault, and we skip the perf event updates.
4748          */
4749         if (!regs)
4750                 return;
4751
4752         if (major)
4753                 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
4754         else
4755                 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
4756 }
4757
4758 /*
4759  * By the time we get here, we already hold the mm semaphore
4760  *
4761  * The mmap_lock may have been released depending on flags and our
4762  * return value.  See filemap_fault() and __lock_page_or_retry().
4763  */
4764 vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
4765                            unsigned int flags, struct pt_regs *regs)
4766 {
4767         vm_fault_t ret;
4768
4769         __set_current_state(TASK_RUNNING);
4770
4771         count_vm_event(PGFAULT);
4772         count_memcg_event_mm(vma->vm_mm, PGFAULT);
4773
4774         /* do counter updates before entering really critical section. */
4775         check_sync_rss_stat(current);
4776
4777         if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
4778                                             flags & FAULT_FLAG_INSTRUCTION,
4779                                             flags & FAULT_FLAG_REMOTE))
4780                 return VM_FAULT_SIGSEGV;
4781
4782         /*
4783          * Enable the memcg OOM handling for faults triggered in user
4784          * space.  Kernel faults are handled more gracefully.
4785          */
4786         if (flags & FAULT_FLAG_USER)
4787                 mem_cgroup_enter_user_fault();
4788
4789         if (unlikely(is_vm_hugetlb_page(vma)))
4790                 ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
4791         else
4792                 ret = __handle_mm_fault(vma, address, flags);
4793
4794         if (flags & FAULT_FLAG_USER) {
4795                 mem_cgroup_exit_user_fault();
4796                 /*
4797                  * The task may have entered a memcg OOM situation but
4798                  * if the allocation error was handled gracefully (no
4799                  * VM_FAULT_OOM), there is no need to kill anything.
4800                  * Just clean up the OOM state peacefully.
4801                  */
4802                 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
4803                         mem_cgroup_oom_synchronize(false);
4804         }
4805
4806         mm_account_fault(regs, address, flags, ret);
4807
4808         return ret;
4809 }
4810 EXPORT_SYMBOL_GPL(handle_mm_fault);
4811
4812 #ifndef __PAGETABLE_P4D_FOLDED
4813 /*
4814  * Allocate p4d page table.
4815  * We've already handled the fast-path in-line.
4816  */
4817 int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
4818 {
4819         p4d_t *new = p4d_alloc_one(mm, address);
4820         if (!new)
4821                 return -ENOMEM;
4822
4823         smp_wmb(); /* See comment in __pte_alloc */
4824
4825         spin_lock(&mm->page_table_lock);
4826         if (pgd_present(*pgd))          /* Another has populated it */
4827                 p4d_free(mm, new);
4828         else
4829                 pgd_populate(mm, pgd, new);
4830         spin_unlock(&mm->page_table_lock);
4831         return 0;
4832 }
4833 #endif /* __PAGETABLE_P4D_FOLDED */
4834
4835 #ifndef __PAGETABLE_PUD_FOLDED
4836 /*
4837  * Allocate page upper directory.
4838  * We've already handled the fast-path in-line.
4839  */
4840 int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
4841 {
4842         pud_t *new = pud_alloc_one(mm, address);
4843         if (!new)
4844                 return -ENOMEM;
4845
4846         smp_wmb(); /* See comment in __pte_alloc */
4847
4848         spin_lock(&mm->page_table_lock);
4849         if (!p4d_present(*p4d)) {
4850                 mm_inc_nr_puds(mm);
4851                 p4d_populate(mm, p4d, new);
4852         } else  /* Another has populated it */
4853                 pud_free(mm, new);
4854         spin_unlock(&mm->page_table_lock);
4855         return 0;
4856 }
4857 #endif /* __PAGETABLE_PUD_FOLDED */
4858
4859 #ifndef __PAGETABLE_PMD_FOLDED
4860 /*
4861  * Allocate page middle directory.
4862  * We've already handled the fast-path in-line.
4863  */
4864 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
4865 {
4866         spinlock_t *ptl;
4867         pmd_t *new = pmd_alloc_one(mm, address);
4868         if (!new)
4869                 return -ENOMEM;
4870
4871         smp_wmb(); /* See comment in __pte_alloc */
4872
4873         ptl = pud_lock(mm, pud);
4874         if (!pud_present(*pud)) {
4875                 mm_inc_nr_pmds(mm);
4876                 pud_populate(mm, pud, new);
4877         } else  /* Another has populated it */
4878                 pmd_free(mm, new);
4879         spin_unlock(ptl);
4880         return 0;
4881 }
4882 #endif /* __PAGETABLE_PMD_FOLDED */
4883
4884 int follow_invalidate_pte(struct mm_struct *mm, unsigned long address,
4885                           struct mmu_notifier_range *range, pte_t **ptepp,
4886                           pmd_t **pmdpp, spinlock_t **ptlp)
4887 {
4888         pgd_t *pgd;
4889         p4d_t *p4d;
4890         pud_t *pud;
4891         pmd_t *pmd;
4892         pte_t *ptep;
4893
4894         pgd = pgd_offset(mm, address);
4895         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
4896                 goto out;
4897
4898         p4d = p4d_offset(pgd, address);
4899         if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d)))
4900                 goto out;
4901
4902         pud = pud_offset(p4d, address);
4903         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
4904                 goto out;
4905
4906         pmd = pmd_offset(pud, address);
4907         VM_BUG_ON(pmd_trans_huge(*pmd));
4908
4909         if (pmd_huge(*pmd)) {
4910                 if (!pmdpp)
4911                         goto out;
4912
4913                 if (range) {
4914                         mmu_notifier_range_init(range, MMU_NOTIFY_CLEAR, 0,
4915                                                 NULL, mm, address & PMD_MASK,
4916                                                 (address & PMD_MASK) + PMD_SIZE);
4917                         mmu_notifier_invalidate_range_start(range);
4918                 }
4919                 *ptlp = pmd_lock(mm, pmd);
4920                 if (pmd_huge(*pmd)) {
4921                         *pmdpp = pmd;
4922                         return 0;
4923                 }
4924                 spin_unlock(*ptlp);
4925                 if (range)
4926                         mmu_notifier_invalidate_range_end(range);
4927         }
4928
4929         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
4930                 goto out;
4931
4932         if (range) {
4933                 mmu_notifier_range_init(range, MMU_NOTIFY_CLEAR, 0, NULL, mm,
4934                                         address & PAGE_MASK,
4935                                         (address & PAGE_MASK) + PAGE_SIZE);
4936                 mmu_notifier_invalidate_range_start(range);
4937         }
4938         ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
4939         if (!pte_present(*ptep))
4940                 goto unlock;
4941         *ptepp = ptep;
4942         return 0;
4943 unlock:
4944         pte_unmap_unlock(ptep, *ptlp);
4945         if (range)
4946                 mmu_notifier_invalidate_range_end(range);
4947 out:
4948         return -EINVAL;
4949 }
4950
4951 /**
4952  * follow_pte - look up PTE at a user virtual address
4953  * @mm: the mm_struct of the target address space
4954  * @address: user virtual address
4955  * @ptepp: location to store found PTE
4956  * @ptlp: location to store the lock for the PTE
4957  *
4958  * On a successful return, the pointer to the PTE is stored in @ptepp;
4959  * the corresponding lock is taken and its location is stored in @ptlp.
4960  * The contents of the PTE are only stable until @ptlp is released;
4961  * any further use, if any, must be protected against invalidation
4962  * with MMU notifiers.
4963  *
4964  * Only IO mappings and raw PFN mappings are allowed.  The mmap semaphore
4965  * should be taken for read.
4966  *
4967  * KVM uses this function.  While it is arguably less bad than ``follow_pfn``,
4968  * it is not a good general-purpose API.
4969  *
4970  * Return: zero on success, -ve otherwise.
4971  */
4972 int follow_pte(struct mm_struct *mm, unsigned long address,
4973                pte_t **ptepp, spinlock_t **ptlp)
4974 {
4975         return follow_invalidate_pte(mm, address, NULL, ptepp, NULL, ptlp);
4976 }
4977 EXPORT_SYMBOL_GPL(follow_pte);
4978
4979 /**
4980  * follow_pfn - look up PFN at a user virtual address
4981  * @vma: memory mapping
4982  * @address: user virtual address
4983  * @pfn: location to store found PFN
4984  *
4985  * Only IO mappings and raw PFN mappings are allowed.
4986  *
4987  * This function does not allow the caller to read the permissions
4988  * of the PTE.  Do not use it.
4989  *
4990  * Return: zero and the pfn at @pfn on success, -ve otherwise.
4991  */
4992 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
4993         unsigned long *pfn)
4994 {
4995         int ret = -EINVAL;
4996         spinlock_t *ptl;
4997         pte_t *ptep;
4998
4999         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
5000                 return ret;
5001
5002         ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
5003         if (ret)
5004                 return ret;
5005         *pfn = pte_pfn(*ptep);
5006         pte_unmap_unlock(ptep, ptl);
5007         return 0;
5008 }
5009 EXPORT_SYMBOL(follow_pfn);
5010
5011 #ifdef CONFIG_HAVE_IOREMAP_PROT
5012 int follow_phys(struct vm_area_struct *vma,
5013                 unsigned long address, unsigned int flags,
5014                 unsigned long *prot, resource_size_t *phys)
5015 {
5016         int ret = -EINVAL;
5017         pte_t *ptep, pte;
5018         spinlock_t *ptl;
5019
5020         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
5021                 goto out;
5022
5023         if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
5024                 goto out;
5025         pte = *ptep;
5026
5027         if ((flags & FOLL_WRITE) && !pte_write(pte))
5028                 goto unlock;
5029
5030         *prot = pgprot_val(pte_pgprot(pte));
5031         *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
5032
5033         ret = 0;
5034 unlock:
5035         pte_unmap_unlock(ptep, ptl);
5036 out:
5037         return ret;
5038 }
5039
5040 /**
5041  * generic_access_phys - generic implementation for iomem mmap access
5042  * @vma: the vma to access
5043  * @addr: userspace address, not relative offset within @vma
5044  * @buf: buffer to read/write
5045  * @len: length of transfer
5046  * @write: set to FOLL_WRITE when writing, otherwise reading
5047  *
5048  * This is a generic implementation for &vm_operations_struct.access for an
5049  * iomem mapping. This callback is used by access_process_vm() when the @vma is
5050  * not page based.
5051  */
5052 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
5053                         void *buf, int len, int write)
5054 {
5055         resource_size_t phys_addr;
5056         unsigned long prot = 0;
5057         void __iomem *maddr;
5058         pte_t *ptep, pte;
5059         spinlock_t *ptl;
5060         int offset = offset_in_page(addr);
5061         int ret = -EINVAL;
5062
5063         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
5064                 return -EINVAL;
5065
5066 retry:
5067         if (follow_pte(vma->vm_mm, addr, &ptep, &ptl))
5068                 return -EINVAL;
5069         pte = *ptep;
5070         pte_unmap_unlock(ptep, ptl);
5071
5072         prot = pgprot_val(pte_pgprot(pte));
5073         phys_addr = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
5074
5075         if ((write & FOLL_WRITE) && !pte_write(pte))
5076                 return -EINVAL;
5077
5078         maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
5079         if (!maddr)
5080                 return -ENOMEM;
5081
5082         if (follow_pte(vma->vm_mm, addr, &ptep, &ptl))
5083                 goto out_unmap;
5084
5085         if (!pte_same(pte, *ptep)) {
5086                 pte_unmap_unlock(ptep, ptl);
5087                 iounmap(maddr);
5088
5089                 goto retry;
5090         }
5091
5092         if (write)
5093                 memcpy_toio(maddr + offset, buf, len);
5094         else
5095                 memcpy_fromio(buf, maddr + offset, len);
5096         ret = len;
5097         pte_unmap_unlock(ptep, ptl);
5098 out_unmap:
5099         iounmap(maddr);
5100
5101         return ret;
5102 }
5103 EXPORT_SYMBOL_GPL(generic_access_phys);
5104 #endif
5105
5106 /*
5107  * Access another process' address space as given in mm.
5108  */
5109 int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf,
5110                        int len, unsigned int gup_flags)
5111 {
5112         struct vm_area_struct *vma;
5113         void *old_buf = buf;
5114         int write = gup_flags & FOLL_WRITE;
5115
5116         if (mmap_read_lock_killable(mm))
5117                 return 0;
5118
5119         /* ignore errors, just check how much was successfully transferred */
5120         while (len) {
5121                 int bytes, ret, offset;
5122                 void *maddr;
5123                 struct page *page = NULL;
5124
5125                 ret = get_user_pages_remote(mm, addr, 1,
5126                                 gup_flags, &page, &vma, NULL);
5127                 if (ret <= 0) {
5128 #ifndef CONFIG_HAVE_IOREMAP_PROT
5129                         break;
5130 #else
5131                         /*
5132                          * Check if this is a VM_IO | VM_PFNMAP VMA, which
5133                          * we can access using slightly different code.
5134                          */
5135                         vma = vma_lookup(mm, addr);
5136                         if (!vma)
5137                                 break;
5138                         if (vma->vm_ops && vma->vm_ops->access)
5139                                 ret = vma->vm_ops->access(vma, addr, buf,
5140                                                           len, write);
5141                         if (ret <= 0)
5142                                 break;
5143                         bytes = ret;
5144 #endif
5145                 } else {
5146                         bytes = len;
5147                         offset = addr & (PAGE_SIZE-1);
5148                         if (bytes > PAGE_SIZE-offset)
5149                                 bytes = PAGE_SIZE-offset;
5150
5151                         maddr = kmap(page);
5152                         if (write) {
5153                                 copy_to_user_page(vma, page, addr,
5154                                                   maddr + offset, buf, bytes);
5155                                 set_page_dirty_lock(page);
5156                         } else {
5157                                 copy_from_user_page(vma, page, addr,
5158                                                     buf, maddr + offset, bytes);
5159                         }
5160                         kunmap(page);
5161                         put_page(page);
5162                 }
5163                 len -= bytes;
5164                 buf += bytes;
5165                 addr += bytes;
5166         }
5167         mmap_read_unlock(mm);
5168
5169         return buf - old_buf;
5170 }
5171
5172 /**
5173  * access_remote_vm - access another process' address space
5174  * @mm:         the mm_struct of the target address space
5175  * @addr:       start address to access
5176  * @buf:        source or destination buffer
5177  * @len:        number of bytes to transfer
5178  * @gup_flags:  flags modifying lookup behaviour
5179  *
5180  * The caller must hold a reference on @mm.
5181  *
5182  * Return: number of bytes copied from source to destination.
5183  */
5184 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
5185                 void *buf, int len, unsigned int gup_flags)
5186 {
5187         return __access_remote_vm(mm, addr, buf, len, gup_flags);
5188 }
5189
5190 /*
5191  * Access another process' address space.
5192  * Source/target buffer must be kernel space,
5193  * Do not walk the page table directly, use get_user_pages
5194  */
5195 int access_process_vm(struct task_struct *tsk, unsigned long addr,
5196                 void *buf, int len, unsigned int gup_flags)
5197 {
5198         struct mm_struct *mm;
5199         int ret;
5200
5201         mm = get_task_mm(tsk);
5202         if (!mm)
5203                 return 0;
5204
5205         ret = __access_remote_vm(mm, addr, buf, len, gup_flags);
5206
5207         mmput(mm);
5208
5209         return ret;
5210 }
5211 EXPORT_SYMBOL_GPL(access_process_vm);
5212
5213 /*
5214  * Print the name of a VMA.
5215  */
5216 void print_vma_addr(char *prefix, unsigned long ip)
5217 {
5218         struct mm_struct *mm = current->mm;
5219         struct vm_area_struct *vma;
5220
5221         /*
5222          * we might be running from an atomic context so we cannot sleep
5223          */
5224         if (!mmap_read_trylock(mm))
5225                 return;
5226
5227         vma = find_vma(mm, ip);
5228         if (vma && vma->vm_file) {
5229                 struct file *f = vma->vm_file;
5230                 char *buf = (char *)__get_free_page(GFP_NOWAIT);
5231                 if (buf) {
5232                         char *p;
5233
5234                         p = file_path(f, buf, PAGE_SIZE);
5235                         if (IS_ERR(p))
5236                                 p = "?";
5237                         printk("%s%s[%lx+%lx]", prefix, kbasename(p),
5238                                         vma->vm_start,
5239                                         vma->vm_end - vma->vm_start);
5240                         free_page((unsigned long)buf);
5241                 }
5242         }
5243         mmap_read_unlock(mm);
5244 }
5245
5246 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
5247 void __might_fault(const char *file, int line)
5248 {
5249         /*
5250          * Some code (nfs/sunrpc) uses socket ops on kernel memory while
5251          * holding the mmap_lock, this is safe because kernel memory doesn't
5252          * get paged out, therefore we'll never actually fault, and the
5253          * below annotations will generate false positives.
5254          */
5255         if (uaccess_kernel())
5256                 return;
5257         if (pagefault_disabled())
5258                 return;
5259         __might_sleep(file, line, 0);
5260 #if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
5261         if (current->mm)
5262                 might_lock_read(&current->mm->mmap_lock);
5263 #endif
5264 }
5265 EXPORT_SYMBOL(__might_fault);
5266 #endif
5267
5268 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
5269 /*
5270  * Process all subpages of the specified huge page with the specified
5271  * operation.  The target subpage will be processed last to keep its
5272  * cache lines hot.
5273  */
5274 static inline void process_huge_page(
5275         unsigned long addr_hint, unsigned int pages_per_huge_page,
5276         void (*process_subpage)(unsigned long addr, int idx, void *arg),
5277         void *arg)
5278 {
5279         int i, n, base, l;
5280         unsigned long addr = addr_hint &
5281                 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
5282
5283         /* Process target subpage last to keep its cache lines hot */
5284         might_sleep();
5285         n = (addr_hint - addr) / PAGE_SIZE;
5286         if (2 * n <= pages_per_huge_page) {
5287                 /* If target subpage in first half of huge page */
5288                 base = 0;
5289                 l = n;
5290                 /* Process subpages at the end of huge page */
5291                 for (i = pages_per_huge_page - 1; i >= 2 * n; i--) {
5292                         cond_resched();
5293                         process_subpage(addr + i * PAGE_SIZE, i, arg);
5294                 }
5295         } else {
5296                 /* If target subpage in second half of huge page */
5297                 base = pages_per_huge_page - 2 * (pages_per_huge_page - n);
5298                 l = pages_per_huge_page - n;
5299                 /* Process subpages at the begin of huge page */
5300                 for (i = 0; i < base; i++) {
5301                         cond_resched();
5302                         process_subpage(addr + i * PAGE_SIZE, i, arg);
5303                 }
5304         }
5305         /*
5306          * Process remaining subpages in left-right-left-right pattern
5307          * towards the target subpage
5308          */
5309         for (i = 0; i < l; i++) {
5310                 int left_idx = base + i;
5311                 int right_idx = base + 2 * l - 1 - i;
5312
5313                 cond_resched();
5314                 process_subpage(addr + left_idx * PAGE_SIZE, left_idx, arg);
5315                 cond_resched();
5316                 process_subpage(addr + right_idx * PAGE_SIZE, right_idx, arg);
5317         }
5318 }
5319
5320 static void clear_gigantic_page(struct page *page,
5321                                 unsigned long addr,
5322                                 unsigned int pages_per_huge_page)
5323 {
5324         int i;
5325         struct page *p = page;
5326
5327         might_sleep();
5328         for (i = 0; i < pages_per_huge_page;
5329              i++, p = mem_map_next(p, page, i)) {
5330                 cond_resched();
5331                 clear_user_highpage(p, addr + i * PAGE_SIZE);
5332         }
5333 }
5334
5335 static void clear_subpage(unsigned long addr, int idx, void *arg)
5336 {
5337         struct page *page = arg;
5338
5339         clear_user_highpage(page + idx, addr);
5340 }
5341
5342 void clear_huge_page(struct page *page,
5343                      unsigned long addr_hint, unsigned int pages_per_huge_page)
5344 {
5345         unsigned long addr = addr_hint &
5346                 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
5347
5348         if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
5349                 clear_gigantic_page(page, addr, pages_per_huge_page);
5350                 return;
5351         }
5352
5353         process_huge_page(addr_hint, pages_per_huge_page, clear_subpage, page);
5354 }
5355
5356 static void copy_user_gigantic_page(struct page *dst, struct page *src,
5357                                     unsigned long addr,
5358                                     struct vm_area_struct *vma,
5359                                     unsigned int pages_per_huge_page)
5360 {
5361         int i;
5362         struct page *dst_base = dst;
5363         struct page *src_base = src;
5364
5365         for (i = 0; i < pages_per_huge_page; ) {
5366                 cond_resched();
5367                 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
5368
5369                 i++;
5370                 dst = mem_map_next(dst, dst_base, i);
5371                 src = mem_map_next(src, src_base, i);
5372         }
5373 }
5374
5375 struct copy_subpage_arg {
5376         struct page *dst;
5377         struct page *src;
5378         struct vm_area_struct *vma;
5379 };
5380
5381 static void copy_subpage(unsigned long addr, int idx, void *arg)
5382 {
5383         struct copy_subpage_arg *copy_arg = arg;
5384
5385         copy_user_highpage(copy_arg->dst + idx, copy_arg->src + idx,
5386                            addr, copy_arg->vma);
5387 }
5388
5389 void copy_user_huge_page(struct page *dst, struct page *src,
5390                          unsigned long addr_hint, struct vm_area_struct *vma,
5391                          unsigned int pages_per_huge_page)
5392 {
5393         unsigned long addr = addr_hint &
5394                 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
5395         struct copy_subpage_arg arg = {
5396                 .dst = dst,
5397                 .src = src,
5398                 .vma = vma,
5399         };
5400
5401         if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
5402                 copy_user_gigantic_page(dst, src, addr, vma,
5403                                         pages_per_huge_page);
5404                 return;
5405         }
5406
5407         process_huge_page(addr_hint, pages_per_huge_page, copy_subpage, &arg);
5408 }
5409
5410 long copy_huge_page_from_user(struct page *dst_page,
5411                                 const void __user *usr_src,
5412                                 unsigned int pages_per_huge_page,
5413                                 bool allow_pagefault)
5414 {
5415         void *src = (void *)usr_src;
5416         void *page_kaddr;
5417         unsigned long i, rc = 0;
5418         unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
5419         struct page *subpage = dst_page;
5420
5421         for (i = 0; i < pages_per_huge_page;
5422              i++, subpage = mem_map_next(subpage, dst_page, i)) {
5423                 if (allow_pagefault)
5424                         page_kaddr = kmap(subpage);
5425                 else
5426                         page_kaddr = kmap_atomic(subpage);
5427                 rc = copy_from_user(page_kaddr,
5428                                 (const void __user *)(src + i * PAGE_SIZE),
5429                                 PAGE_SIZE);
5430                 if (allow_pagefault)
5431                         kunmap(subpage);
5432                 else
5433                         kunmap_atomic(page_kaddr);
5434
5435                 ret_val -= (PAGE_SIZE - rc);
5436                 if (rc)
5437                         break;
5438
5439                 cond_resched();
5440         }
5441         return ret_val;
5442 }
5443 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
5444
5445 #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
5446
5447 static struct kmem_cache *page_ptl_cachep;
5448
5449 void __init ptlock_cache_init(void)
5450 {
5451         page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
5452                         SLAB_PANIC, NULL);
5453 }
5454
5455 bool ptlock_alloc(struct page *page)
5456 {
5457         spinlock_t *ptl;
5458
5459         ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
5460         if (!ptl)
5461                 return false;
5462         page->ptl = ptl;
5463         return true;
5464 }
5465
5466 void ptlock_free(struct page *page)
5467 {
5468         kmem_cache_free(page_ptl_cachep, page->ptl);
5469 }
5470 #endif