Remove internal use of 'write_access' in mm/memory.c
[linux-2.6.git] / mm / memory.c
1 /*
2  *  linux/mm/memory.c
3  *
4  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
5  */
6
7 /*
8  * demand-loading started 01.12.91 - seems it is high on the list of
9  * things wanted, and it should be easy to implement. - Linus
10  */
11
12 /*
13  * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14  * pages started 02.12.91, seems to work. - Linus.
15  *
16  * Tested sharing by executing about 30 /bin/sh: under the old kernel it
17  * would have taken more than the 6M I have free, but it worked well as
18  * far as I could see.
19  *
20  * Also corrected some "invalidate()"s - I wasn't doing enough of them.
21  */
22
23 /*
24  * Real VM (paging to/from disk) started 18.12.91. Much more work and
25  * thought has to go into this. Oh, well..
26  * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
27  *              Found it. Everything seems to work now.
28  * 20.12.91  -  Ok, making the swap-device changeable like the root.
29  */
30
31 /*
32  * 05.04.94  -  Multi-page memory management added for v1.1.
33  *              Idea by Alex Bligh (alex@cconcepts.co.uk)
34  *
35  * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
36  *              (Gerhard.Wichert@pdb.siemens.de)
37  *
38  * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
39  */
40
41 #include <linux/kernel_stat.h>
42 #include <linux/mm.h>
43 #include <linux/hugetlb.h>
44 #include <linux/mman.h>
45 #include <linux/swap.h>
46 #include <linux/highmem.h>
47 #include <linux/pagemap.h>
48 #include <linux/rmap.h>
49 #include <linux/module.h>
50 #include <linux/delayacct.h>
51 #include <linux/init.h>
52 #include <linux/writeback.h>
53 #include <linux/memcontrol.h>
54 #include <linux/mmu_notifier.h>
55 #include <linux/kallsyms.h>
56 #include <linux/swapops.h>
57 #include <linux/elf.h>
58
59 #include <asm/pgalloc.h>
60 #include <asm/uaccess.h>
61 #include <asm/tlb.h>
62 #include <asm/tlbflush.h>
63 #include <asm/pgtable.h>
64
65 #include "internal.h"
66
67 #ifndef CONFIG_NEED_MULTIPLE_NODES
68 /* use the per-pgdat data instead for discontigmem - mbligh */
69 unsigned long max_mapnr;
70 struct page *mem_map;
71
72 EXPORT_SYMBOL(max_mapnr);
73 EXPORT_SYMBOL(mem_map);
74 #endif
75
76 unsigned long num_physpages;
77 /*
78  * A number of key systems in x86 including ioremap() rely on the assumption
79  * that high_memory defines the upper bound on direct map memory, then end
80  * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
81  * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
82  * and ZONE_HIGHMEM.
83  */
84 void * high_memory;
85
86 EXPORT_SYMBOL(num_physpages);
87 EXPORT_SYMBOL(high_memory);
88
89 /*
90  * Randomize the address space (stacks, mmaps, brk, etc.).
91  *
92  * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
93  *   as ancient (libc5 based) binaries can segfault. )
94  */
95 int randomize_va_space __read_mostly =
96 #ifdef CONFIG_COMPAT_BRK
97                                         1;
98 #else
99                                         2;
100 #endif
101
102 static int __init disable_randmaps(char *s)
103 {
104         randomize_va_space = 0;
105         return 1;
106 }
107 __setup("norandmaps", disable_randmaps);
108
109
110 /*
111  * If a p?d_bad entry is found while walking page tables, report
112  * the error, before resetting entry to p?d_none.  Usually (but
113  * very seldom) called out from the p?d_none_or_clear_bad macros.
114  */
115
116 void pgd_clear_bad(pgd_t *pgd)
117 {
118         pgd_ERROR(*pgd);
119         pgd_clear(pgd);
120 }
121
122 void pud_clear_bad(pud_t *pud)
123 {
124         pud_ERROR(*pud);
125         pud_clear(pud);
126 }
127
128 void pmd_clear_bad(pmd_t *pmd)
129 {
130         pmd_ERROR(*pmd);
131         pmd_clear(pmd);
132 }
133
134 /*
135  * Note: this doesn't free the actual pages themselves. That
136  * has been handled earlier when unmapping all the memory regions.
137  */
138 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
139 {
140         pgtable_t token = pmd_pgtable(*pmd);
141         pmd_clear(pmd);
142         pte_free_tlb(tlb, token);
143         tlb->mm->nr_ptes--;
144 }
145
146 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
147                                 unsigned long addr, unsigned long end,
148                                 unsigned long floor, unsigned long ceiling)
149 {
150         pmd_t *pmd;
151         unsigned long next;
152         unsigned long start;
153
154         start = addr;
155         pmd = pmd_offset(pud, addr);
156         do {
157                 next = pmd_addr_end(addr, end);
158                 if (pmd_none_or_clear_bad(pmd))
159                         continue;
160                 free_pte_range(tlb, pmd);
161         } while (pmd++, addr = next, addr != end);
162
163         start &= PUD_MASK;
164         if (start < floor)
165                 return;
166         if (ceiling) {
167                 ceiling &= PUD_MASK;
168                 if (!ceiling)
169                         return;
170         }
171         if (end - 1 > ceiling - 1)
172                 return;
173
174         pmd = pmd_offset(pud, start);
175         pud_clear(pud);
176         pmd_free_tlb(tlb, pmd);
177 }
178
179 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
180                                 unsigned long addr, unsigned long end,
181                                 unsigned long floor, unsigned long ceiling)
182 {
183         pud_t *pud;
184         unsigned long next;
185         unsigned long start;
186
187         start = addr;
188         pud = pud_offset(pgd, addr);
189         do {
190                 next = pud_addr_end(addr, end);
191                 if (pud_none_or_clear_bad(pud))
192                         continue;
193                 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
194         } while (pud++, addr = next, addr != end);
195
196         start &= PGDIR_MASK;
197         if (start < floor)
198                 return;
199         if (ceiling) {
200                 ceiling &= PGDIR_MASK;
201                 if (!ceiling)
202                         return;
203         }
204         if (end - 1 > ceiling - 1)
205                 return;
206
207         pud = pud_offset(pgd, start);
208         pgd_clear(pgd);
209         pud_free_tlb(tlb, pud);
210 }
211
212 /*
213  * This function frees user-level page tables of a process.
214  *
215  * Must be called with pagetable lock held.
216  */
217 void free_pgd_range(struct mmu_gather *tlb,
218                         unsigned long addr, unsigned long end,
219                         unsigned long floor, unsigned long ceiling)
220 {
221         pgd_t *pgd;
222         unsigned long next;
223         unsigned long start;
224
225         /*
226          * The next few lines have given us lots of grief...
227          *
228          * Why are we testing PMD* at this top level?  Because often
229          * there will be no work to do at all, and we'd prefer not to
230          * go all the way down to the bottom just to discover that.
231          *
232          * Why all these "- 1"s?  Because 0 represents both the bottom
233          * of the address space and the top of it (using -1 for the
234          * top wouldn't help much: the masks would do the wrong thing).
235          * The rule is that addr 0 and floor 0 refer to the bottom of
236          * the address space, but end 0 and ceiling 0 refer to the top
237          * Comparisons need to use "end - 1" and "ceiling - 1" (though
238          * that end 0 case should be mythical).
239          *
240          * Wherever addr is brought up or ceiling brought down, we must
241          * be careful to reject "the opposite 0" before it confuses the
242          * subsequent tests.  But what about where end is brought down
243          * by PMD_SIZE below? no, end can't go down to 0 there.
244          *
245          * Whereas we round start (addr) and ceiling down, by different
246          * masks at different levels, in order to test whether a table
247          * now has no other vmas using it, so can be freed, we don't
248          * bother to round floor or end up - the tests don't need that.
249          */
250
251         addr &= PMD_MASK;
252         if (addr < floor) {
253                 addr += PMD_SIZE;
254                 if (!addr)
255                         return;
256         }
257         if (ceiling) {
258                 ceiling &= PMD_MASK;
259                 if (!ceiling)
260                         return;
261         }
262         if (end - 1 > ceiling - 1)
263                 end -= PMD_SIZE;
264         if (addr > end - 1)
265                 return;
266
267         start = addr;
268         pgd = pgd_offset(tlb->mm, addr);
269         do {
270                 next = pgd_addr_end(addr, end);
271                 if (pgd_none_or_clear_bad(pgd))
272                         continue;
273                 free_pud_range(tlb, pgd, addr, next, floor, ceiling);
274         } while (pgd++, addr = next, addr != end);
275 }
276
277 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
278                 unsigned long floor, unsigned long ceiling)
279 {
280         while (vma) {
281                 struct vm_area_struct *next = vma->vm_next;
282                 unsigned long addr = vma->vm_start;
283
284                 /*
285                  * Hide vma from rmap and vmtruncate before freeing pgtables
286                  */
287                 anon_vma_unlink(vma);
288                 unlink_file_vma(vma);
289
290                 if (is_vm_hugetlb_page(vma)) {
291                         hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
292                                 floor, next? next->vm_start: ceiling);
293                 } else {
294                         /*
295                          * Optimization: gather nearby vmas into one call down
296                          */
297                         while (next && next->vm_start <= vma->vm_end + PMD_SIZE
298                                && !is_vm_hugetlb_page(next)) {
299                                 vma = next;
300                                 next = vma->vm_next;
301                                 anon_vma_unlink(vma);
302                                 unlink_file_vma(vma);
303                         }
304                         free_pgd_range(tlb, addr, vma->vm_end,
305                                 floor, next? next->vm_start: ceiling);
306                 }
307                 vma = next;
308         }
309 }
310
311 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
312 {
313         pgtable_t new = pte_alloc_one(mm, address);
314         if (!new)
315                 return -ENOMEM;
316
317         /*
318          * Ensure all pte setup (eg. pte page lock and page clearing) are
319          * visible before the pte is made visible to other CPUs by being
320          * put into page tables.
321          *
322          * The other side of the story is the pointer chasing in the page
323          * table walking code (when walking the page table without locking;
324          * ie. most of the time). Fortunately, these data accesses consist
325          * of a chain of data-dependent loads, meaning most CPUs (alpha
326          * being the notable exception) will already guarantee loads are
327          * seen in-order. See the alpha page table accessors for the
328          * smp_read_barrier_depends() barriers in page table walking code.
329          */
330         smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
331
332         spin_lock(&mm->page_table_lock);
333         if (!pmd_present(*pmd)) {       /* Has another populated it ? */
334                 mm->nr_ptes++;
335                 pmd_populate(mm, pmd, new);
336                 new = NULL;
337         }
338         spin_unlock(&mm->page_table_lock);
339         if (new)
340                 pte_free(mm, new);
341         return 0;
342 }
343
344 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
345 {
346         pte_t *new = pte_alloc_one_kernel(&init_mm, address);
347         if (!new)
348                 return -ENOMEM;
349
350         smp_wmb(); /* See comment in __pte_alloc */
351
352         spin_lock(&init_mm.page_table_lock);
353         if (!pmd_present(*pmd)) {       /* Has another populated it ? */
354                 pmd_populate_kernel(&init_mm, pmd, new);
355                 new = NULL;
356         }
357         spin_unlock(&init_mm.page_table_lock);
358         if (new)
359                 pte_free_kernel(&init_mm, new);
360         return 0;
361 }
362
363 static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
364 {
365         if (file_rss)
366                 add_mm_counter(mm, file_rss, file_rss);
367         if (anon_rss)
368                 add_mm_counter(mm, anon_rss, anon_rss);
369 }
370
371 /*
372  * This function is called to print an error when a bad pte
373  * is found. For example, we might have a PFN-mapped pte in
374  * a region that doesn't allow it.
375  *
376  * The calling function must still handle the error.
377  */
378 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
379                           pte_t pte, struct page *page)
380 {
381         pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
382         pud_t *pud = pud_offset(pgd, addr);
383         pmd_t *pmd = pmd_offset(pud, addr);
384         struct address_space *mapping;
385         pgoff_t index;
386         static unsigned long resume;
387         static unsigned long nr_shown;
388         static unsigned long nr_unshown;
389
390         /*
391          * Allow a burst of 60 reports, then keep quiet for that minute;
392          * or allow a steady drip of one report per second.
393          */
394         if (nr_shown == 60) {
395                 if (time_before(jiffies, resume)) {
396                         nr_unshown++;
397                         return;
398                 }
399                 if (nr_unshown) {
400                         printk(KERN_ALERT
401                                 "BUG: Bad page map: %lu messages suppressed\n",
402                                 nr_unshown);
403                         nr_unshown = 0;
404                 }
405                 nr_shown = 0;
406         }
407         if (nr_shown++ == 0)
408                 resume = jiffies + 60 * HZ;
409
410         mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
411         index = linear_page_index(vma, addr);
412
413         printk(KERN_ALERT
414                 "BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
415                 current->comm,
416                 (long long)pte_val(pte), (long long)pmd_val(*pmd));
417         if (page) {
418                 printk(KERN_ALERT
419                 "page:%p flags:%p count:%d mapcount:%d mapping:%p index:%lx\n",
420                 page, (void *)page->flags, page_count(page),
421                 page_mapcount(page), page->mapping, page->index);
422         }
423         printk(KERN_ALERT
424                 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
425                 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
426         /*
427          * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
428          */
429         if (vma->vm_ops)
430                 print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
431                                 (unsigned long)vma->vm_ops->fault);
432         if (vma->vm_file && vma->vm_file->f_op)
433                 print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
434                                 (unsigned long)vma->vm_file->f_op->mmap);
435         dump_stack();
436         add_taint(TAINT_BAD_PAGE);
437 }
438
439 static inline int is_cow_mapping(unsigned int flags)
440 {
441         return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
442 }
443
444 /*
445  * vm_normal_page -- This function gets the "struct page" associated with a pte.
446  *
447  * "Special" mappings do not wish to be associated with a "struct page" (either
448  * it doesn't exist, or it exists but they don't want to touch it). In this
449  * case, NULL is returned here. "Normal" mappings do have a struct page.
450  *
451  * There are 2 broad cases. Firstly, an architecture may define a pte_special()
452  * pte bit, in which case this function is trivial. Secondly, an architecture
453  * may not have a spare pte bit, which requires a more complicated scheme,
454  * described below.
455  *
456  * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
457  * special mapping (even if there are underlying and valid "struct pages").
458  * COWed pages of a VM_PFNMAP are always normal.
459  *
460  * The way we recognize COWed pages within VM_PFNMAP mappings is through the
461  * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
462  * set, and the vm_pgoff will point to the first PFN mapped: thus every special
463  * mapping will always honor the rule
464  *
465  *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
466  *
467  * And for normal mappings this is false.
468  *
469  * This restricts such mappings to be a linear translation from virtual address
470  * to pfn. To get around this restriction, we allow arbitrary mappings so long
471  * as the vma is not a COW mapping; in that case, we know that all ptes are
472  * special (because none can have been COWed).
473  *
474  *
475  * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
476  *
477  * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
478  * page" backing, however the difference is that _all_ pages with a struct
479  * page (that is, those where pfn_valid is true) are refcounted and considered
480  * normal pages by the VM. The disadvantage is that pages are refcounted
481  * (which can be slower and simply not an option for some PFNMAP users). The
482  * advantage is that we don't have to follow the strict linearity rule of
483  * PFNMAP mappings in order to support COWable mappings.
484  *
485  */
486 #ifdef __HAVE_ARCH_PTE_SPECIAL
487 # define HAVE_PTE_SPECIAL 1
488 #else
489 # define HAVE_PTE_SPECIAL 0
490 #endif
491 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
492                                 pte_t pte)
493 {
494         unsigned long pfn = pte_pfn(pte);
495
496         if (HAVE_PTE_SPECIAL) {
497                 if (likely(!pte_special(pte)))
498                         goto check_pfn;
499                 if (!(vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)))
500                         print_bad_pte(vma, addr, pte, NULL);
501                 return NULL;
502         }
503
504         /* !HAVE_PTE_SPECIAL case follows: */
505
506         if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
507                 if (vma->vm_flags & VM_MIXEDMAP) {
508                         if (!pfn_valid(pfn))
509                                 return NULL;
510                         goto out;
511                 } else {
512                         unsigned long off;
513                         off = (addr - vma->vm_start) >> PAGE_SHIFT;
514                         if (pfn == vma->vm_pgoff + off)
515                                 return NULL;
516                         if (!is_cow_mapping(vma->vm_flags))
517                                 return NULL;
518                 }
519         }
520
521 check_pfn:
522         if (unlikely(pfn > highest_memmap_pfn)) {
523                 print_bad_pte(vma, addr, pte, NULL);
524                 return NULL;
525         }
526
527         /*
528          * NOTE! We still have PageReserved() pages in the page tables.
529          * eg. VDSO mappings can cause them to exist.
530          */
531 out:
532         return pfn_to_page(pfn);
533 }
534
535 /*
536  * copy one vm_area from one task to the other. Assumes the page tables
537  * already present in the new task to be cleared in the whole range
538  * covered by this vma.
539  */
540
541 static inline void
542 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
543                 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
544                 unsigned long addr, int *rss)
545 {
546         unsigned long vm_flags = vma->vm_flags;
547         pte_t pte = *src_pte;
548         struct page *page;
549
550         /* pte contains position in swap or file, so copy. */
551         if (unlikely(!pte_present(pte))) {
552                 if (!pte_file(pte)) {
553                         swp_entry_t entry = pte_to_swp_entry(pte);
554
555                         swap_duplicate(entry);
556                         /* make sure dst_mm is on swapoff's mmlist. */
557                         if (unlikely(list_empty(&dst_mm->mmlist))) {
558                                 spin_lock(&mmlist_lock);
559                                 if (list_empty(&dst_mm->mmlist))
560                                         list_add(&dst_mm->mmlist,
561                                                  &src_mm->mmlist);
562                                 spin_unlock(&mmlist_lock);
563                         }
564                         if (is_write_migration_entry(entry) &&
565                                         is_cow_mapping(vm_flags)) {
566                                 /*
567                                  * COW mappings require pages in both parent
568                                  * and child to be set to read.
569                                  */
570                                 make_migration_entry_read(&entry);
571                                 pte = swp_entry_to_pte(entry);
572                                 set_pte_at(src_mm, addr, src_pte, pte);
573                         }
574                 }
575                 goto out_set_pte;
576         }
577
578         /*
579          * If it's a COW mapping, write protect it both
580          * in the parent and the child
581          */
582         if (is_cow_mapping(vm_flags)) {
583                 ptep_set_wrprotect(src_mm, addr, src_pte);
584                 pte = pte_wrprotect(pte);
585         }
586
587         /*
588          * If it's a shared mapping, mark it clean in
589          * the child
590          */
591         if (vm_flags & VM_SHARED)
592                 pte = pte_mkclean(pte);
593         pte = pte_mkold(pte);
594
595         page = vm_normal_page(vma, addr, pte);
596         if (page) {
597                 get_page(page);
598                 page_dup_rmap(page, vma, addr);
599                 rss[!!PageAnon(page)]++;
600         }
601
602 out_set_pte:
603         set_pte_at(dst_mm, addr, dst_pte, pte);
604 }
605
606 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
607                 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
608                 unsigned long addr, unsigned long end)
609 {
610         pte_t *src_pte, *dst_pte;
611         spinlock_t *src_ptl, *dst_ptl;
612         int progress = 0;
613         int rss[2];
614
615 again:
616         rss[1] = rss[0] = 0;
617         dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
618         if (!dst_pte)
619                 return -ENOMEM;
620         src_pte = pte_offset_map_nested(src_pmd, addr);
621         src_ptl = pte_lockptr(src_mm, src_pmd);
622         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
623         arch_enter_lazy_mmu_mode();
624
625         do {
626                 /*
627                  * We are holding two locks at this point - either of them
628                  * could generate latencies in another task on another CPU.
629                  */
630                 if (progress >= 32) {
631                         progress = 0;
632                         if (need_resched() ||
633                             spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
634                                 break;
635                 }
636                 if (pte_none(*src_pte)) {
637                         progress++;
638                         continue;
639                 }
640                 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
641                 progress += 8;
642         } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
643
644         arch_leave_lazy_mmu_mode();
645         spin_unlock(src_ptl);
646         pte_unmap_nested(src_pte - 1);
647         add_mm_rss(dst_mm, rss[0], rss[1]);
648         pte_unmap_unlock(dst_pte - 1, dst_ptl);
649         cond_resched();
650         if (addr != end)
651                 goto again;
652         return 0;
653 }
654
655 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
656                 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
657                 unsigned long addr, unsigned long end)
658 {
659         pmd_t *src_pmd, *dst_pmd;
660         unsigned long next;
661
662         dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
663         if (!dst_pmd)
664                 return -ENOMEM;
665         src_pmd = pmd_offset(src_pud, addr);
666         do {
667                 next = pmd_addr_end(addr, end);
668                 if (pmd_none_or_clear_bad(src_pmd))
669                         continue;
670                 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
671                                                 vma, addr, next))
672                         return -ENOMEM;
673         } while (dst_pmd++, src_pmd++, addr = next, addr != end);
674         return 0;
675 }
676
677 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
678                 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
679                 unsigned long addr, unsigned long end)
680 {
681         pud_t *src_pud, *dst_pud;
682         unsigned long next;
683
684         dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
685         if (!dst_pud)
686                 return -ENOMEM;
687         src_pud = pud_offset(src_pgd, addr);
688         do {
689                 next = pud_addr_end(addr, end);
690                 if (pud_none_or_clear_bad(src_pud))
691                         continue;
692                 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
693                                                 vma, addr, next))
694                         return -ENOMEM;
695         } while (dst_pud++, src_pud++, addr = next, addr != end);
696         return 0;
697 }
698
699 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
700                 struct vm_area_struct *vma)
701 {
702         pgd_t *src_pgd, *dst_pgd;
703         unsigned long next;
704         unsigned long addr = vma->vm_start;
705         unsigned long end = vma->vm_end;
706         int ret;
707
708         /*
709          * Don't copy ptes where a page fault will fill them correctly.
710          * Fork becomes much lighter when there are big shared or private
711          * readonly mappings. The tradeoff is that copy_page_range is more
712          * efficient than faulting.
713          */
714         if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
715                 if (!vma->anon_vma)
716                         return 0;
717         }
718
719         if (is_vm_hugetlb_page(vma))
720                 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
721
722         if (unlikely(is_pfn_mapping(vma))) {
723                 /*
724                  * We do not free on error cases below as remove_vma
725                  * gets called on error from higher level routine
726                  */
727                 ret = track_pfn_vma_copy(vma);
728                 if (ret)
729                         return ret;
730         }
731
732         /*
733          * We need to invalidate the secondary MMU mappings only when
734          * there could be a permission downgrade on the ptes of the
735          * parent mm. And a permission downgrade will only happen if
736          * is_cow_mapping() returns true.
737          */
738         if (is_cow_mapping(vma->vm_flags))
739                 mmu_notifier_invalidate_range_start(src_mm, addr, end);
740
741         ret = 0;
742         dst_pgd = pgd_offset(dst_mm, addr);
743         src_pgd = pgd_offset(src_mm, addr);
744         do {
745                 next = pgd_addr_end(addr, end);
746                 if (pgd_none_or_clear_bad(src_pgd))
747                         continue;
748                 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
749                                             vma, addr, next))) {
750                         ret = -ENOMEM;
751                         break;
752                 }
753         } while (dst_pgd++, src_pgd++, addr = next, addr != end);
754
755         if (is_cow_mapping(vma->vm_flags))
756                 mmu_notifier_invalidate_range_end(src_mm,
757                                                   vma->vm_start, end);
758         return ret;
759 }
760
761 static unsigned long zap_pte_range(struct mmu_gather *tlb,
762                                 struct vm_area_struct *vma, pmd_t *pmd,
763                                 unsigned long addr, unsigned long end,
764                                 long *zap_work, struct zap_details *details)
765 {
766         struct mm_struct *mm = tlb->mm;
767         pte_t *pte;
768         spinlock_t *ptl;
769         int file_rss = 0;
770         int anon_rss = 0;
771
772         pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
773         arch_enter_lazy_mmu_mode();
774         do {
775                 pte_t ptent = *pte;
776                 if (pte_none(ptent)) {
777                         (*zap_work)--;
778                         continue;
779                 }
780
781                 (*zap_work) -= PAGE_SIZE;
782
783                 if (pte_present(ptent)) {
784                         struct page *page;
785
786                         page = vm_normal_page(vma, addr, ptent);
787                         if (unlikely(details) && page) {
788                                 /*
789                                  * unmap_shared_mapping_pages() wants to
790                                  * invalidate cache without truncating:
791                                  * unmap shared but keep private pages.
792                                  */
793                                 if (details->check_mapping &&
794                                     details->check_mapping != page->mapping)
795                                         continue;
796                                 /*
797                                  * Each page->index must be checked when
798                                  * invalidating or truncating nonlinear.
799                                  */
800                                 if (details->nonlinear_vma &&
801                                     (page->index < details->first_index ||
802                                      page->index > details->last_index))
803                                         continue;
804                         }
805                         ptent = ptep_get_and_clear_full(mm, addr, pte,
806                                                         tlb->fullmm);
807                         tlb_remove_tlb_entry(tlb, pte, addr);
808                         if (unlikely(!page))
809                                 continue;
810                         if (unlikely(details) && details->nonlinear_vma
811                             && linear_page_index(details->nonlinear_vma,
812                                                 addr) != page->index)
813                                 set_pte_at(mm, addr, pte,
814                                            pgoff_to_pte(page->index));
815                         if (PageAnon(page))
816                                 anon_rss--;
817                         else {
818                                 if (pte_dirty(ptent))
819                                         set_page_dirty(page);
820                                 if (pte_young(ptent) &&
821                                     likely(!VM_SequentialReadHint(vma)))
822                                         mark_page_accessed(page);
823                                 file_rss--;
824                         }
825                         page_remove_rmap(page);
826                         if (unlikely(page_mapcount(page) < 0))
827                                 print_bad_pte(vma, addr, ptent, page);
828                         tlb_remove_page(tlb, page);
829                         continue;
830                 }
831                 /*
832                  * If details->check_mapping, we leave swap entries;
833                  * if details->nonlinear_vma, we leave file entries.
834                  */
835                 if (unlikely(details))
836                         continue;
837                 if (pte_file(ptent)) {
838                         if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
839                                 print_bad_pte(vma, addr, ptent, NULL);
840                 } else if
841                   (unlikely(!free_swap_and_cache(pte_to_swp_entry(ptent))))
842                         print_bad_pte(vma, addr, ptent, NULL);
843                 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
844         } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
845
846         add_mm_rss(mm, file_rss, anon_rss);
847         arch_leave_lazy_mmu_mode();
848         pte_unmap_unlock(pte - 1, ptl);
849
850         return addr;
851 }
852
853 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
854                                 struct vm_area_struct *vma, pud_t *pud,
855                                 unsigned long addr, unsigned long end,
856                                 long *zap_work, struct zap_details *details)
857 {
858         pmd_t *pmd;
859         unsigned long next;
860
861         pmd = pmd_offset(pud, addr);
862         do {
863                 next = pmd_addr_end(addr, end);
864                 if (pmd_none_or_clear_bad(pmd)) {
865                         (*zap_work)--;
866                         continue;
867                 }
868                 next = zap_pte_range(tlb, vma, pmd, addr, next,
869                                                 zap_work, details);
870         } while (pmd++, addr = next, (addr != end && *zap_work > 0));
871
872         return addr;
873 }
874
875 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
876                                 struct vm_area_struct *vma, pgd_t *pgd,
877                                 unsigned long addr, unsigned long end,
878                                 long *zap_work, struct zap_details *details)
879 {
880         pud_t *pud;
881         unsigned long next;
882
883         pud = pud_offset(pgd, addr);
884         do {
885                 next = pud_addr_end(addr, end);
886                 if (pud_none_or_clear_bad(pud)) {
887                         (*zap_work)--;
888                         continue;
889                 }
890                 next = zap_pmd_range(tlb, vma, pud, addr, next,
891                                                 zap_work, details);
892         } while (pud++, addr = next, (addr != end && *zap_work > 0));
893
894         return addr;
895 }
896
897 static unsigned long unmap_page_range(struct mmu_gather *tlb,
898                                 struct vm_area_struct *vma,
899                                 unsigned long addr, unsigned long end,
900                                 long *zap_work, struct zap_details *details)
901 {
902         pgd_t *pgd;
903         unsigned long next;
904
905         if (details && !details->check_mapping && !details->nonlinear_vma)
906                 details = NULL;
907
908         BUG_ON(addr >= end);
909         tlb_start_vma(tlb, vma);
910         pgd = pgd_offset(vma->vm_mm, addr);
911         do {
912                 next = pgd_addr_end(addr, end);
913                 if (pgd_none_or_clear_bad(pgd)) {
914                         (*zap_work)--;
915                         continue;
916                 }
917                 next = zap_pud_range(tlb, vma, pgd, addr, next,
918                                                 zap_work, details);
919         } while (pgd++, addr = next, (addr != end && *zap_work > 0));
920         tlb_end_vma(tlb, vma);
921
922         return addr;
923 }
924
925 #ifdef CONFIG_PREEMPT
926 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
927 #else
928 /* No preempt: go for improved straight-line efficiency */
929 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
930 #endif
931
932 /**
933  * unmap_vmas - unmap a range of memory covered by a list of vma's
934  * @tlbp: address of the caller's struct mmu_gather
935  * @vma: the starting vma
936  * @start_addr: virtual address at which to start unmapping
937  * @end_addr: virtual address at which to end unmapping
938  * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
939  * @details: details of nonlinear truncation or shared cache invalidation
940  *
941  * Returns the end address of the unmapping (restart addr if interrupted).
942  *
943  * Unmap all pages in the vma list.
944  *
945  * We aim to not hold locks for too long (for scheduling latency reasons).
946  * So zap pages in ZAP_BLOCK_SIZE bytecounts.  This means we need to
947  * return the ending mmu_gather to the caller.
948  *
949  * Only addresses between `start' and `end' will be unmapped.
950  *
951  * The VMA list must be sorted in ascending virtual address order.
952  *
953  * unmap_vmas() assumes that the caller will flush the whole unmapped address
954  * range after unmap_vmas() returns.  So the only responsibility here is to
955  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
956  * drops the lock and schedules.
957  */
958 unsigned long unmap_vmas(struct mmu_gather **tlbp,
959                 struct vm_area_struct *vma, unsigned long start_addr,
960                 unsigned long end_addr, unsigned long *nr_accounted,
961                 struct zap_details *details)
962 {
963         long zap_work = ZAP_BLOCK_SIZE;
964         unsigned long tlb_start = 0;    /* For tlb_finish_mmu */
965         int tlb_start_valid = 0;
966         unsigned long start = start_addr;
967         spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
968         int fullmm = (*tlbp)->fullmm;
969         struct mm_struct *mm = vma->vm_mm;
970
971         mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
972         for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
973                 unsigned long end;
974
975                 start = max(vma->vm_start, start_addr);
976                 if (start >= vma->vm_end)
977                         continue;
978                 end = min(vma->vm_end, end_addr);
979                 if (end <= vma->vm_start)
980                         continue;
981
982                 if (vma->vm_flags & VM_ACCOUNT)
983                         *nr_accounted += (end - start) >> PAGE_SHIFT;
984
985                 if (unlikely(is_pfn_mapping(vma)))
986                         untrack_pfn_vma(vma, 0, 0);
987
988                 while (start != end) {
989                         if (!tlb_start_valid) {
990                                 tlb_start = start;
991                                 tlb_start_valid = 1;
992                         }
993
994                         if (unlikely(is_vm_hugetlb_page(vma))) {
995                                 /*
996                                  * It is undesirable to test vma->vm_file as it
997                                  * should be non-null for valid hugetlb area.
998                                  * However, vm_file will be NULL in the error
999                                  * cleanup path of do_mmap_pgoff. When
1000                                  * hugetlbfs ->mmap method fails,
1001                                  * do_mmap_pgoff() nullifies vma->vm_file
1002                                  * before calling this function to clean up.
1003                                  * Since no pte has actually been setup, it is
1004                                  * safe to do nothing in this case.
1005                                  */
1006                                 if (vma->vm_file) {
1007                                         unmap_hugepage_range(vma, start, end, NULL);
1008                                         zap_work -= (end - start) /
1009                                         pages_per_huge_page(hstate_vma(vma));
1010                                 }
1011
1012                                 start = end;
1013                         } else
1014                                 start = unmap_page_range(*tlbp, vma,
1015                                                 start, end, &zap_work, details);
1016
1017                         if (zap_work > 0) {
1018                                 BUG_ON(start != end);
1019                                 break;
1020                         }
1021
1022                         tlb_finish_mmu(*tlbp, tlb_start, start);
1023
1024                         if (need_resched() ||
1025                                 (i_mmap_lock && spin_needbreak(i_mmap_lock))) {
1026                                 if (i_mmap_lock) {
1027                                         *tlbp = NULL;
1028                                         goto out;
1029                                 }
1030                                 cond_resched();
1031                         }
1032
1033                         *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
1034                         tlb_start_valid = 0;
1035                         zap_work = ZAP_BLOCK_SIZE;
1036                 }
1037         }
1038 out:
1039         mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1040         return start;   /* which is now the end (or restart) address */
1041 }
1042
1043 /**
1044  * zap_page_range - remove user pages in a given range
1045  * @vma: vm_area_struct holding the applicable pages
1046  * @address: starting address of pages to zap
1047  * @size: number of bytes to zap
1048  * @details: details of nonlinear truncation or shared cache invalidation
1049  */
1050 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
1051                 unsigned long size, struct zap_details *details)
1052 {
1053         struct mm_struct *mm = vma->vm_mm;
1054         struct mmu_gather *tlb;
1055         unsigned long end = address + size;
1056         unsigned long nr_accounted = 0;
1057
1058         lru_add_drain();
1059         tlb = tlb_gather_mmu(mm, 0);
1060         update_hiwater_rss(mm);
1061         end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
1062         if (tlb)
1063                 tlb_finish_mmu(tlb, address, end);
1064         return end;
1065 }
1066
1067 /**
1068  * zap_vma_ptes - remove ptes mapping the vma
1069  * @vma: vm_area_struct holding ptes to be zapped
1070  * @address: starting address of pages to zap
1071  * @size: number of bytes to zap
1072  *
1073  * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1074  *
1075  * The entire address range must be fully contained within the vma.
1076  *
1077  * Returns 0 if successful.
1078  */
1079 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1080                 unsigned long size)
1081 {
1082         if (address < vma->vm_start || address + size > vma->vm_end ||
1083                         !(vma->vm_flags & VM_PFNMAP))
1084                 return -1;
1085         zap_page_range(vma, address, size, NULL);
1086         return 0;
1087 }
1088 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1089
1090 /*
1091  * Do a quick page-table lookup for a single page.
1092  */
1093 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1094                         unsigned int flags)
1095 {
1096         pgd_t *pgd;
1097         pud_t *pud;
1098         pmd_t *pmd;
1099         pte_t *ptep, pte;
1100         spinlock_t *ptl;
1101         struct page *page;
1102         struct mm_struct *mm = vma->vm_mm;
1103
1104         page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1105         if (!IS_ERR(page)) {
1106                 BUG_ON(flags & FOLL_GET);
1107                 goto out;
1108         }
1109
1110         page = NULL;
1111         pgd = pgd_offset(mm, address);
1112         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1113                 goto no_page_table;
1114
1115         pud = pud_offset(pgd, address);
1116         if (pud_none(*pud))
1117                 goto no_page_table;
1118         if (pud_huge(*pud)) {
1119                 BUG_ON(flags & FOLL_GET);
1120                 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1121                 goto out;
1122         }
1123         if (unlikely(pud_bad(*pud)))
1124                 goto no_page_table;
1125
1126         pmd = pmd_offset(pud, address);
1127         if (pmd_none(*pmd))
1128                 goto no_page_table;
1129         if (pmd_huge(*pmd)) {
1130                 BUG_ON(flags & FOLL_GET);
1131                 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1132                 goto out;
1133         }
1134         if (unlikely(pmd_bad(*pmd)))
1135                 goto no_page_table;
1136
1137         ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1138
1139         pte = *ptep;
1140         if (!pte_present(pte))
1141                 goto no_page;
1142         if ((flags & FOLL_WRITE) && !pte_write(pte))
1143                 goto unlock;
1144         page = vm_normal_page(vma, address, pte);
1145         if (unlikely(!page))
1146                 goto bad_page;
1147
1148         if (flags & FOLL_GET)
1149                 get_page(page);
1150         if (flags & FOLL_TOUCH) {
1151                 if ((flags & FOLL_WRITE) &&
1152                     !pte_dirty(pte) && !PageDirty(page))
1153                         set_page_dirty(page);
1154                 /*
1155                  * pte_mkyoung() would be more correct here, but atomic care
1156                  * is needed to avoid losing the dirty bit: it is easier to use
1157                  * mark_page_accessed().
1158                  */
1159                 mark_page_accessed(page);
1160         }
1161 unlock:
1162         pte_unmap_unlock(ptep, ptl);
1163 out:
1164         return page;
1165
1166 bad_page:
1167         pte_unmap_unlock(ptep, ptl);
1168         return ERR_PTR(-EFAULT);
1169
1170 no_page:
1171         pte_unmap_unlock(ptep, ptl);
1172         if (!pte_none(pte))
1173                 return page;
1174         /* Fall through to ZERO_PAGE handling */
1175 no_page_table:
1176         /*
1177          * When core dumping an enormous anonymous area that nobody
1178          * has touched so far, we don't want to allocate page tables.
1179          */
1180         if (flags & FOLL_ANON) {
1181                 page = ZERO_PAGE(0);
1182                 if (flags & FOLL_GET)
1183                         get_page(page);
1184                 BUG_ON(flags & FOLL_WRITE);
1185         }
1186         return page;
1187 }
1188
1189 /* Can we do the FOLL_ANON optimization? */
1190 static inline int use_zero_page(struct vm_area_struct *vma)
1191 {
1192         /*
1193          * We don't want to optimize FOLL_ANON for make_pages_present()
1194          * when it tries to page in a VM_LOCKED region. As to VM_SHARED,
1195          * we want to get the page from the page tables to make sure
1196          * that we serialize and update with any other user of that
1197          * mapping.
1198          */
1199         if (vma->vm_flags & (VM_LOCKED | VM_SHARED))
1200                 return 0;
1201         /*
1202          * And if we have a fault routine, it's not an anonymous region.
1203          */
1204         return !vma->vm_ops || !vma->vm_ops->fault;
1205 }
1206
1207
1208
1209 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1210                      unsigned long start, int len, int flags,
1211                 struct page **pages, struct vm_area_struct **vmas)
1212 {
1213         int i;
1214         unsigned int vm_flags = 0;
1215         int write = !!(flags & GUP_FLAGS_WRITE);
1216         int force = !!(flags & GUP_FLAGS_FORCE);
1217         int ignore = !!(flags & GUP_FLAGS_IGNORE_VMA_PERMISSIONS);
1218         int ignore_sigkill = !!(flags & GUP_FLAGS_IGNORE_SIGKILL);
1219
1220         if (len <= 0)
1221                 return 0;
1222         /* 
1223          * Require read or write permissions.
1224          * If 'force' is set, we only require the "MAY" flags.
1225          */
1226         vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1227         vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1228         i = 0;
1229
1230         do {
1231                 struct vm_area_struct *vma;
1232                 unsigned int foll_flags;
1233
1234                 vma = find_extend_vma(mm, start);
1235                 if (!vma && in_gate_area(tsk, start)) {
1236                         unsigned long pg = start & PAGE_MASK;
1237                         struct vm_area_struct *gate_vma = get_gate_vma(tsk);
1238                         pgd_t *pgd;
1239                         pud_t *pud;
1240                         pmd_t *pmd;
1241                         pte_t *pte;
1242
1243                         /* user gate pages are read-only */
1244                         if (!ignore && write)
1245                                 return i ? : -EFAULT;
1246                         if (pg > TASK_SIZE)
1247                                 pgd = pgd_offset_k(pg);
1248                         else
1249                                 pgd = pgd_offset_gate(mm, pg);
1250                         BUG_ON(pgd_none(*pgd));
1251                         pud = pud_offset(pgd, pg);
1252                         BUG_ON(pud_none(*pud));
1253                         pmd = pmd_offset(pud, pg);
1254                         if (pmd_none(*pmd))
1255                                 return i ? : -EFAULT;
1256                         pte = pte_offset_map(pmd, pg);
1257                         if (pte_none(*pte)) {
1258                                 pte_unmap(pte);
1259                                 return i ? : -EFAULT;
1260                         }
1261                         if (pages) {
1262                                 struct page *page = vm_normal_page(gate_vma, start, *pte);
1263                                 pages[i] = page;
1264                                 if (page)
1265                                         get_page(page);
1266                         }
1267                         pte_unmap(pte);
1268                         if (vmas)
1269                                 vmas[i] = gate_vma;
1270                         i++;
1271                         start += PAGE_SIZE;
1272                         len--;
1273                         continue;
1274                 }
1275
1276                 if (!vma ||
1277                     (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
1278                     (!ignore && !(vm_flags & vma->vm_flags)))
1279                         return i ? : -EFAULT;
1280
1281                 if (is_vm_hugetlb_page(vma)) {
1282                         i = follow_hugetlb_page(mm, vma, pages, vmas,
1283                                                 &start, &len, i, write);
1284                         continue;
1285                 }
1286
1287                 foll_flags = FOLL_TOUCH;
1288                 if (pages)
1289                         foll_flags |= FOLL_GET;
1290                 if (!write && use_zero_page(vma))
1291                         foll_flags |= FOLL_ANON;
1292
1293                 do {
1294                         struct page *page;
1295
1296                         /*
1297                          * If we have a pending SIGKILL, don't keep faulting
1298                          * pages and potentially allocating memory, unless
1299                          * current is handling munlock--e.g., on exit. In
1300                          * that case, we are not allocating memory.  Rather,
1301                          * we're only unlocking already resident/mapped pages.
1302                          */
1303                         if (unlikely(!ignore_sigkill &&
1304                                         fatal_signal_pending(current)))
1305                                 return i ? i : -ERESTARTSYS;
1306
1307                         if (write)
1308                                 foll_flags |= FOLL_WRITE;
1309
1310                         cond_resched();
1311                         while (!(page = follow_page(vma, start, foll_flags))) {
1312                                 int ret;
1313                                 ret = handle_mm_fault(mm, vma, start,
1314                                                 foll_flags & FOLL_WRITE);
1315                                 if (ret & VM_FAULT_ERROR) {
1316                                         if (ret & VM_FAULT_OOM)
1317                                                 return i ? i : -ENOMEM;
1318                                         else if (ret & VM_FAULT_SIGBUS)
1319                                                 return i ? i : -EFAULT;
1320                                         BUG();
1321                                 }
1322                                 if (ret & VM_FAULT_MAJOR)
1323                                         tsk->maj_flt++;
1324                                 else
1325                                         tsk->min_flt++;
1326
1327                                 /*
1328                                  * The VM_FAULT_WRITE bit tells us that
1329                                  * do_wp_page has broken COW when necessary,
1330                                  * even if maybe_mkwrite decided not to set
1331                                  * pte_write. We can thus safely do subsequent
1332                                  * page lookups as if they were reads. But only
1333                                  * do so when looping for pte_write is futile:
1334                                  * in some cases userspace may also be wanting
1335                                  * to write to the gotten user page, which a
1336                                  * read fault here might prevent (a readonly
1337                                  * page might get reCOWed by userspace write).
1338                                  */
1339                                 if ((ret & VM_FAULT_WRITE) &&
1340                                     !(vma->vm_flags & VM_WRITE))
1341                                         foll_flags &= ~FOLL_WRITE;
1342
1343                                 cond_resched();
1344                         }
1345                         if (IS_ERR(page))
1346                                 return i ? i : PTR_ERR(page);
1347                         if (pages) {
1348                                 pages[i] = page;
1349
1350                                 flush_anon_page(vma, page, start);
1351                                 flush_dcache_page(page);
1352                         }
1353                         if (vmas)
1354                                 vmas[i] = vma;
1355                         i++;
1356                         start += PAGE_SIZE;
1357                         len--;
1358                 } while (len && start < vma->vm_end);
1359         } while (len);
1360         return i;
1361 }
1362
1363 /**
1364  * get_user_pages() - pin user pages in memory
1365  * @tsk:        task_struct of target task
1366  * @mm:         mm_struct of target mm
1367  * @start:      starting user address
1368  * @len:        number of pages from start to pin
1369  * @write:      whether pages will be written to by the caller
1370  * @force:      whether to force write access even if user mapping is
1371  *              readonly. This will result in the page being COWed even
1372  *              in MAP_SHARED mappings. You do not want this.
1373  * @pages:      array that receives pointers to the pages pinned.
1374  *              Should be at least nr_pages long. Or NULL, if caller
1375  *              only intends to ensure the pages are faulted in.
1376  * @vmas:       array of pointers to vmas corresponding to each page.
1377  *              Or NULL if the caller does not require them.
1378  *
1379  * Returns number of pages pinned. This may be fewer than the number
1380  * requested. If len is 0 or negative, returns 0. If no pages
1381  * were pinned, returns -errno. Each page returned must be released
1382  * with a put_page() call when it is finished with. vmas will only
1383  * remain valid while mmap_sem is held.
1384  *
1385  * Must be called with mmap_sem held for read or write.
1386  *
1387  * get_user_pages walks a process's page tables and takes a reference to
1388  * each struct page that each user address corresponds to at a given
1389  * instant. That is, it takes the page that would be accessed if a user
1390  * thread accesses the given user virtual address at that instant.
1391  *
1392  * This does not guarantee that the page exists in the user mappings when
1393  * get_user_pages returns, and there may even be a completely different
1394  * page there in some cases (eg. if mmapped pagecache has been invalidated
1395  * and subsequently re faulted). However it does guarantee that the page
1396  * won't be freed completely. And mostly callers simply care that the page
1397  * contains data that was valid *at some point in time*. Typically, an IO
1398  * or similar operation cannot guarantee anything stronger anyway because
1399  * locks can't be held over the syscall boundary.
1400  *
1401  * If write=0, the page must not be written to. If the page is written to,
1402  * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1403  * after the page is finished with, and before put_page is called.
1404  *
1405  * get_user_pages is typically used for fewer-copy IO operations, to get a
1406  * handle on the memory by some means other than accesses via the user virtual
1407  * addresses. The pages may be submitted for DMA to devices or accessed via
1408  * their kernel linear mapping (via the kmap APIs). Care should be taken to
1409  * use the correct cache flushing APIs.
1410  *
1411  * See also get_user_pages_fast, for performance critical applications.
1412  */
1413 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1414                 unsigned long start, int len, int write, int force,
1415                 struct page **pages, struct vm_area_struct **vmas)
1416 {
1417         int flags = 0;
1418
1419         if (write)
1420                 flags |= GUP_FLAGS_WRITE;
1421         if (force)
1422                 flags |= GUP_FLAGS_FORCE;
1423
1424         return __get_user_pages(tsk, mm,
1425                                 start, len, flags,
1426                                 pages, vmas);
1427 }
1428
1429 EXPORT_SYMBOL(get_user_pages);
1430
1431 pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
1432                         spinlock_t **ptl)
1433 {
1434         pgd_t * pgd = pgd_offset(mm, addr);
1435         pud_t * pud = pud_alloc(mm, pgd, addr);
1436         if (pud) {
1437                 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1438                 if (pmd)
1439                         return pte_alloc_map_lock(mm, pmd, addr, ptl);
1440         }
1441         return NULL;
1442 }
1443
1444 /*
1445  * This is the old fallback for page remapping.
1446  *
1447  * For historical reasons, it only allows reserved pages. Only
1448  * old drivers should use this, and they needed to mark their
1449  * pages reserved for the old functions anyway.
1450  */
1451 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1452                         struct page *page, pgprot_t prot)
1453 {
1454         struct mm_struct *mm = vma->vm_mm;
1455         int retval;
1456         pte_t *pte;
1457         spinlock_t *ptl;
1458
1459         retval = -EINVAL;
1460         if (PageAnon(page))
1461                 goto out;
1462         retval = -ENOMEM;
1463         flush_dcache_page(page);
1464         pte = get_locked_pte(mm, addr, &ptl);
1465         if (!pte)
1466                 goto out;
1467         retval = -EBUSY;
1468         if (!pte_none(*pte))
1469                 goto out_unlock;
1470
1471         /* Ok, finally just insert the thing.. */
1472         get_page(page);
1473         inc_mm_counter(mm, file_rss);
1474         page_add_file_rmap(page);
1475         set_pte_at(mm, addr, pte, mk_pte(page, prot));
1476
1477         retval = 0;
1478         pte_unmap_unlock(pte, ptl);
1479         return retval;
1480 out_unlock:
1481         pte_unmap_unlock(pte, ptl);
1482 out:
1483         return retval;
1484 }
1485
1486 /**
1487  * vm_insert_page - insert single page into user vma
1488  * @vma: user vma to map to
1489  * @addr: target user address of this page
1490  * @page: source kernel page
1491  *
1492  * This allows drivers to insert individual pages they've allocated
1493  * into a user vma.
1494  *
1495  * The page has to be a nice clean _individual_ kernel allocation.
1496  * If you allocate a compound page, you need to have marked it as
1497  * such (__GFP_COMP), or manually just split the page up yourself
1498  * (see split_page()).
1499  *
1500  * NOTE! Traditionally this was done with "remap_pfn_range()" which
1501  * took an arbitrary page protection parameter. This doesn't allow
1502  * that. Your vma protection will have to be set up correctly, which
1503  * means that if you want a shared writable mapping, you'd better
1504  * ask for a shared writable mapping!
1505  *
1506  * The page does not need to be reserved.
1507  */
1508 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1509                         struct page *page)
1510 {
1511         if (addr < vma->vm_start || addr >= vma->vm_end)
1512                 return -EFAULT;
1513         if (!page_count(page))
1514                 return -EINVAL;
1515         vma->vm_flags |= VM_INSERTPAGE;
1516         return insert_page(vma, addr, page, vma->vm_page_prot);
1517 }
1518 EXPORT_SYMBOL(vm_insert_page);
1519
1520 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1521                         unsigned long pfn, pgprot_t prot)
1522 {
1523         struct mm_struct *mm = vma->vm_mm;
1524         int retval;
1525         pte_t *pte, entry;
1526         spinlock_t *ptl;
1527
1528         retval = -ENOMEM;
1529         pte = get_locked_pte(mm, addr, &ptl);
1530         if (!pte)
1531                 goto out;
1532         retval = -EBUSY;
1533         if (!pte_none(*pte))
1534                 goto out_unlock;
1535
1536         /* Ok, finally just insert the thing.. */
1537         entry = pte_mkspecial(pfn_pte(pfn, prot));
1538         set_pte_at(mm, addr, pte, entry);
1539         update_mmu_cache(vma, addr, entry); /* XXX: why not for insert_page? */
1540
1541         retval = 0;
1542 out_unlock:
1543         pte_unmap_unlock(pte, ptl);
1544 out:
1545         return retval;
1546 }
1547
1548 /**
1549  * vm_insert_pfn - insert single pfn into user vma
1550  * @vma: user vma to map to
1551  * @addr: target user address of this page
1552  * @pfn: source kernel pfn
1553  *
1554  * Similar to vm_inert_page, this allows drivers to insert individual pages
1555  * they've allocated into a user vma. Same comments apply.
1556  *
1557  * This function should only be called from a vm_ops->fault handler, and
1558  * in that case the handler should return NULL.
1559  *
1560  * vma cannot be a COW mapping.
1561  *
1562  * As this is called only for pages that do not currently exist, we
1563  * do not need to flush old virtual caches or the TLB.
1564  */
1565 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1566                         unsigned long pfn)
1567 {
1568         int ret;
1569         pgprot_t pgprot = vma->vm_page_prot;
1570         /*
1571          * Technically, architectures with pte_special can avoid all these
1572          * restrictions (same for remap_pfn_range).  However we would like
1573          * consistency in testing and feature parity among all, so we should
1574          * try to keep these invariants in place for everybody.
1575          */
1576         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1577         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1578                                                 (VM_PFNMAP|VM_MIXEDMAP));
1579         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1580         BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1581
1582         if (addr < vma->vm_start || addr >= vma->vm_end)
1583                 return -EFAULT;
1584         if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
1585                 return -EINVAL;
1586
1587         ret = insert_pfn(vma, addr, pfn, pgprot);
1588
1589         if (ret)
1590                 untrack_pfn_vma(vma, pfn, PAGE_SIZE);
1591
1592         return ret;
1593 }
1594 EXPORT_SYMBOL(vm_insert_pfn);
1595
1596 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1597                         unsigned long pfn)
1598 {
1599         BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
1600
1601         if (addr < vma->vm_start || addr >= vma->vm_end)
1602                 return -EFAULT;
1603
1604         /*
1605          * If we don't have pte special, then we have to use the pfn_valid()
1606          * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1607          * refcount the page if pfn_valid is true (hence insert_page rather
1608          * than insert_pfn).
1609          */
1610         if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
1611                 struct page *page;
1612
1613                 page = pfn_to_page(pfn);
1614                 return insert_page(vma, addr, page, vma->vm_page_prot);
1615         }
1616         return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
1617 }
1618 EXPORT_SYMBOL(vm_insert_mixed);
1619
1620 /*
1621  * maps a range of physical memory into the requested pages. the old
1622  * mappings are removed. any references to nonexistent pages results
1623  * in null mappings (currently treated as "copy-on-access")
1624  */
1625 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1626                         unsigned long addr, unsigned long end,
1627                         unsigned long pfn, pgprot_t prot)
1628 {
1629         pte_t *pte;
1630         spinlock_t *ptl;
1631
1632         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1633         if (!pte)
1634                 return -ENOMEM;
1635         arch_enter_lazy_mmu_mode();
1636         do {
1637                 BUG_ON(!pte_none(*pte));
1638                 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1639                 pfn++;
1640         } while (pte++, addr += PAGE_SIZE, addr != end);
1641         arch_leave_lazy_mmu_mode();
1642         pte_unmap_unlock(pte - 1, ptl);
1643         return 0;
1644 }
1645
1646 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1647                         unsigned long addr, unsigned long end,
1648                         unsigned long pfn, pgprot_t prot)
1649 {
1650         pmd_t *pmd;
1651         unsigned long next;
1652
1653         pfn -= addr >> PAGE_SHIFT;
1654         pmd = pmd_alloc(mm, pud, addr);
1655         if (!pmd)
1656                 return -ENOMEM;
1657         do {
1658                 next = pmd_addr_end(addr, end);
1659                 if (remap_pte_range(mm, pmd, addr, next,
1660                                 pfn + (addr >> PAGE_SHIFT), prot))
1661                         return -ENOMEM;
1662         } while (pmd++, addr = next, addr != end);
1663         return 0;
1664 }
1665
1666 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1667                         unsigned long addr, unsigned long end,
1668                         unsigned long pfn, pgprot_t prot)
1669 {
1670         pud_t *pud;
1671         unsigned long next;
1672
1673         pfn -= addr >> PAGE_SHIFT;
1674         pud = pud_alloc(mm, pgd, addr);
1675         if (!pud)
1676                 return -ENOMEM;
1677         do {
1678                 next = pud_addr_end(addr, end);
1679                 if (remap_pmd_range(mm, pud, addr, next,
1680                                 pfn + (addr >> PAGE_SHIFT), prot))
1681                         return -ENOMEM;
1682         } while (pud++, addr = next, addr != end);
1683         return 0;
1684 }
1685
1686 /**
1687  * remap_pfn_range - remap kernel memory to userspace
1688  * @vma: user vma to map to
1689  * @addr: target user address to start at
1690  * @pfn: physical address of kernel memory
1691  * @size: size of map area
1692  * @prot: page protection flags for this mapping
1693  *
1694  *  Note: this is only safe if the mm semaphore is held when called.
1695  */
1696 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1697                     unsigned long pfn, unsigned long size, pgprot_t prot)
1698 {
1699         pgd_t *pgd;
1700         unsigned long next;
1701         unsigned long end = addr + PAGE_ALIGN(size);
1702         struct mm_struct *mm = vma->vm_mm;
1703         int err;
1704
1705         /*
1706          * Physically remapped pages are special. Tell the
1707          * rest of the world about it:
1708          *   VM_IO tells people not to look at these pages
1709          *      (accesses can have side effects).
1710          *   VM_RESERVED is specified all over the place, because
1711          *      in 2.4 it kept swapout's vma scan off this vma; but
1712          *      in 2.6 the LRU scan won't even find its pages, so this
1713          *      flag means no more than count its pages in reserved_vm,
1714          *      and omit it from core dump, even when VM_IO turned off.
1715          *   VM_PFNMAP tells the core MM that the base pages are just
1716          *      raw PFN mappings, and do not have a "struct page" associated
1717          *      with them.
1718          *
1719          * There's a horrible special case to handle copy-on-write
1720          * behaviour that some programs depend on. We mark the "original"
1721          * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1722          */
1723         if (addr == vma->vm_start && end == vma->vm_end) {
1724                 vma->vm_pgoff = pfn;
1725                 vma->vm_flags |= VM_PFN_AT_MMAP;
1726         } else if (is_cow_mapping(vma->vm_flags))
1727                 return -EINVAL;
1728
1729         vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1730
1731         err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
1732         if (err) {
1733                 /*
1734                  * To indicate that track_pfn related cleanup is not
1735                  * needed from higher level routine calling unmap_vmas
1736                  */
1737                 vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
1738                 vma->vm_flags &= ~VM_PFN_AT_MMAP;
1739                 return -EINVAL;
1740         }
1741
1742         BUG_ON(addr >= end);
1743         pfn -= addr >> PAGE_SHIFT;
1744         pgd = pgd_offset(mm, addr);
1745         flush_cache_range(vma, addr, end);
1746         do {
1747                 next = pgd_addr_end(addr, end);
1748                 err = remap_pud_range(mm, pgd, addr, next,
1749                                 pfn + (addr >> PAGE_SHIFT), prot);
1750                 if (err)
1751                         break;
1752         } while (pgd++, addr = next, addr != end);
1753
1754         if (err)
1755                 untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
1756
1757         return err;
1758 }
1759 EXPORT_SYMBOL(remap_pfn_range);
1760
1761 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
1762                                      unsigned long addr, unsigned long end,
1763                                      pte_fn_t fn, void *data)
1764 {
1765         pte_t *pte;
1766         int err;
1767         pgtable_t token;
1768         spinlock_t *uninitialized_var(ptl);
1769
1770         pte = (mm == &init_mm) ?
1771                 pte_alloc_kernel(pmd, addr) :
1772                 pte_alloc_map_lock(mm, pmd, addr, &ptl);
1773         if (!pte)
1774                 return -ENOMEM;
1775
1776         BUG_ON(pmd_huge(*pmd));
1777
1778         arch_enter_lazy_mmu_mode();
1779
1780         token = pmd_pgtable(*pmd);
1781
1782         do {
1783                 err = fn(pte, token, addr, data);
1784                 if (err)
1785                         break;
1786         } while (pte++, addr += PAGE_SIZE, addr != end);
1787
1788         arch_leave_lazy_mmu_mode();
1789
1790         if (mm != &init_mm)
1791                 pte_unmap_unlock(pte-1, ptl);
1792         return err;
1793 }
1794
1795 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
1796                                      unsigned long addr, unsigned long end,
1797                                      pte_fn_t fn, void *data)
1798 {
1799         pmd_t *pmd;
1800         unsigned long next;
1801         int err;
1802
1803         BUG_ON(pud_huge(*pud));
1804
1805         pmd = pmd_alloc(mm, pud, addr);
1806         if (!pmd)
1807                 return -ENOMEM;
1808         do {
1809                 next = pmd_addr_end(addr, end);
1810                 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
1811                 if (err)
1812                         break;
1813         } while (pmd++, addr = next, addr != end);
1814         return err;
1815 }
1816
1817 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
1818                                      unsigned long addr, unsigned long end,
1819                                      pte_fn_t fn, void *data)
1820 {
1821         pud_t *pud;
1822         unsigned long next;
1823         int err;
1824
1825         pud = pud_alloc(mm, pgd, addr);
1826         if (!pud)
1827                 return -ENOMEM;
1828         do {
1829                 next = pud_addr_end(addr, end);
1830                 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
1831                 if (err)
1832                         break;
1833         } while (pud++, addr = next, addr != end);
1834         return err;
1835 }
1836
1837 /*
1838  * Scan a region of virtual memory, filling in page tables as necessary
1839  * and calling a provided function on each leaf page table.
1840  */
1841 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
1842                         unsigned long size, pte_fn_t fn, void *data)
1843 {
1844         pgd_t *pgd;
1845         unsigned long next;
1846         unsigned long start = addr, end = addr + size;
1847         int err;
1848
1849         BUG_ON(addr >= end);
1850         mmu_notifier_invalidate_range_start(mm, start, end);
1851         pgd = pgd_offset(mm, addr);
1852         do {
1853                 next = pgd_addr_end(addr, end);
1854                 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
1855                 if (err)
1856                         break;
1857         } while (pgd++, addr = next, addr != end);
1858         mmu_notifier_invalidate_range_end(mm, start, end);
1859         return err;
1860 }
1861 EXPORT_SYMBOL_GPL(apply_to_page_range);
1862
1863 /*
1864  * handle_pte_fault chooses page fault handler according to an entry
1865  * which was read non-atomically.  Before making any commitment, on
1866  * those architectures or configurations (e.g. i386 with PAE) which
1867  * might give a mix of unmatched parts, do_swap_page and do_file_page
1868  * must check under lock before unmapping the pte and proceeding
1869  * (but do_wp_page is only called after already making such a check;
1870  * and do_anonymous_page and do_no_page can safely check later on).
1871  */
1872 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1873                                 pte_t *page_table, pte_t orig_pte)
1874 {
1875         int same = 1;
1876 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1877         if (sizeof(pte_t) > sizeof(unsigned long)) {
1878                 spinlock_t *ptl = pte_lockptr(mm, pmd);
1879                 spin_lock(ptl);
1880                 same = pte_same(*page_table, orig_pte);
1881                 spin_unlock(ptl);
1882         }
1883 #endif
1884         pte_unmap(page_table);
1885         return same;
1886 }
1887
1888 /*
1889  * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
1890  * servicing faults for write access.  In the normal case, do always want
1891  * pte_mkwrite.  But get_user_pages can cause write faults for mappings
1892  * that do not have writing enabled, when used by access_process_vm.
1893  */
1894 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
1895 {
1896         if (likely(vma->vm_flags & VM_WRITE))
1897                 pte = pte_mkwrite(pte);
1898         return pte;
1899 }
1900
1901 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1902 {
1903         /*
1904          * If the source page was a PFN mapping, we don't have
1905          * a "struct page" for it. We do a best-effort copy by
1906          * just copying from the original user address. If that
1907          * fails, we just zero-fill it. Live with it.
1908          */
1909         if (unlikely(!src)) {
1910                 void *kaddr = kmap_atomic(dst, KM_USER0);
1911                 void __user *uaddr = (void __user *)(va & PAGE_MASK);
1912
1913                 /*
1914                  * This really shouldn't fail, because the page is there
1915                  * in the page tables. But it might just be unreadable,
1916                  * in which case we just give up and fill the result with
1917                  * zeroes.
1918                  */
1919                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1920                         memset(kaddr, 0, PAGE_SIZE);
1921                 kunmap_atomic(kaddr, KM_USER0);
1922                 flush_dcache_page(dst);
1923         } else
1924                 copy_user_highpage(dst, src, va, vma);
1925 }
1926
1927 /*
1928  * This routine handles present pages, when users try to write
1929  * to a shared page. It is done by copying the page to a new address
1930  * and decrementing the shared-page counter for the old page.
1931  *
1932  * Note that this routine assumes that the protection checks have been
1933  * done by the caller (the low-level page fault routine in most cases).
1934  * Thus we can safely just mark it writable once we've done any necessary
1935  * COW.
1936  *
1937  * We also mark the page dirty at this point even though the page will
1938  * change only once the write actually happens. This avoids a few races,
1939  * and potentially makes it more efficient.
1940  *
1941  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1942  * but allow concurrent faults), with pte both mapped and locked.
1943  * We return with mmap_sem still held, but pte unmapped and unlocked.
1944  */
1945 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1946                 unsigned long address, pte_t *page_table, pmd_t *pmd,
1947                 spinlock_t *ptl, pte_t orig_pte)
1948 {
1949         struct page *old_page, *new_page;
1950         pte_t entry;
1951         int reuse = 0, ret = 0;
1952         int page_mkwrite = 0;
1953         struct page *dirty_page = NULL;
1954
1955         old_page = vm_normal_page(vma, address, orig_pte);
1956         if (!old_page) {
1957                 /*
1958                  * VM_MIXEDMAP !pfn_valid() case
1959                  *
1960                  * We should not cow pages in a shared writeable mapping.
1961                  * Just mark the pages writable as we can't do any dirty
1962                  * accounting on raw pfn maps.
1963                  */
1964                 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1965                                      (VM_WRITE|VM_SHARED))
1966                         goto reuse;
1967                 goto gotten;
1968         }
1969
1970         /*
1971          * Take out anonymous pages first, anonymous shared vmas are
1972          * not dirty accountable.
1973          */
1974         if (PageAnon(old_page)) {
1975                 if (!trylock_page(old_page)) {
1976                         page_cache_get(old_page);
1977                         pte_unmap_unlock(page_table, ptl);
1978                         lock_page(old_page);
1979                         page_table = pte_offset_map_lock(mm, pmd, address,
1980                                                          &ptl);
1981                         if (!pte_same(*page_table, orig_pte)) {
1982                                 unlock_page(old_page);
1983                                 page_cache_release(old_page);
1984                                 goto unlock;
1985                         }
1986                         page_cache_release(old_page);
1987                 }
1988                 reuse = reuse_swap_page(old_page);
1989                 unlock_page(old_page);
1990         } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1991                                         (VM_WRITE|VM_SHARED))) {
1992                 /*
1993                  * Only catch write-faults on shared writable pages,
1994                  * read-only shared pages can get COWed by
1995                  * get_user_pages(.write=1, .force=1).
1996                  */
1997                 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
1998                         struct vm_fault vmf;
1999                         int tmp;
2000
2001                         vmf.virtual_address = (void __user *)(address &
2002                                                                 PAGE_MASK);
2003                         vmf.pgoff = old_page->index;
2004                         vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2005                         vmf.page = old_page;
2006
2007                         /*
2008                          * Notify the address space that the page is about to
2009                          * become writable so that it can prohibit this or wait
2010                          * for the page to get into an appropriate state.
2011                          *
2012                          * We do this without the lock held, so that it can
2013                          * sleep if it needs to.
2014                          */
2015                         page_cache_get(old_page);
2016                         pte_unmap_unlock(page_table, ptl);
2017
2018                         tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2019                         if (unlikely(tmp &
2020                                         (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2021                                 ret = tmp;
2022                                 goto unwritable_page;
2023                         }
2024                         if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2025                                 lock_page(old_page);
2026                                 if (!old_page->mapping) {
2027                                         ret = 0; /* retry the fault */
2028                                         unlock_page(old_page);
2029                                         goto unwritable_page;
2030                                 }
2031                         } else
2032                                 VM_BUG_ON(!PageLocked(old_page));
2033
2034                         /*
2035                          * Since we dropped the lock we need to revalidate
2036                          * the PTE as someone else may have changed it.  If
2037                          * they did, we just return, as we can count on the
2038                          * MMU to tell us if they didn't also make it writable.
2039                          */
2040                         page_table = pte_offset_map_lock(mm, pmd, address,
2041                                                          &ptl);
2042                         if (!pte_same(*page_table, orig_pte)) {
2043                                 unlock_page(old_page);
2044                                 page_cache_release(old_page);
2045                                 goto unlock;
2046                         }
2047
2048                         page_mkwrite = 1;
2049                 }
2050                 dirty_page = old_page;
2051                 get_page(dirty_page);
2052                 reuse = 1;
2053         }
2054
2055         if (reuse) {
2056 reuse:
2057                 flush_cache_page(vma, address, pte_pfn(orig_pte));
2058                 entry = pte_mkyoung(orig_pte);
2059                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2060                 if (ptep_set_access_flags(vma, address, page_table, entry,1))
2061                         update_mmu_cache(vma, address, entry);
2062                 ret |= VM_FAULT_WRITE;
2063                 goto unlock;
2064         }
2065
2066         /*
2067          * Ok, we need to copy. Oh, well..
2068          */
2069         page_cache_get(old_page);
2070 gotten:
2071         pte_unmap_unlock(page_table, ptl);
2072
2073         if (unlikely(anon_vma_prepare(vma)))
2074                 goto oom;
2075         VM_BUG_ON(old_page == ZERO_PAGE(0));
2076         new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2077         if (!new_page)
2078                 goto oom;
2079         /*
2080          * Don't let another task, with possibly unlocked vma,
2081          * keep the mlocked page.
2082          */
2083         if ((vma->vm_flags & VM_LOCKED) && old_page) {
2084                 lock_page(old_page);    /* for LRU manipulation */
2085                 clear_page_mlock(old_page);
2086                 unlock_page(old_page);
2087         }
2088         cow_user_page(new_page, old_page, address, vma);
2089         __SetPageUptodate(new_page);
2090
2091         if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2092                 goto oom_free_new;
2093
2094         /*
2095          * Re-check the pte - we dropped the lock
2096          */
2097         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2098         if (likely(pte_same(*page_table, orig_pte))) {
2099                 if (old_page) {
2100                         if (!PageAnon(old_page)) {
2101                                 dec_mm_counter(mm, file_rss);
2102                                 inc_mm_counter(mm, anon_rss);
2103                         }
2104                 } else
2105                         inc_mm_counter(mm, anon_rss);
2106                 flush_cache_page(vma, address, pte_pfn(orig_pte));
2107                 entry = mk_pte(new_page, vma->vm_page_prot);
2108                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2109                 /*
2110                  * Clear the pte entry and flush it first, before updating the
2111                  * pte with the new entry. This will avoid a race condition
2112                  * seen in the presence of one thread doing SMC and another
2113                  * thread doing COW.
2114                  */
2115                 ptep_clear_flush_notify(vma, address, page_table);
2116                 page_add_new_anon_rmap(new_page, vma, address);
2117                 set_pte_at(mm, address, page_table, entry);
2118                 update_mmu_cache(vma, address, entry);
2119                 if (old_page) {
2120                         /*
2121                          * Only after switching the pte to the new page may
2122                          * we remove the mapcount here. Otherwise another
2123                          * process may come and find the rmap count decremented
2124                          * before the pte is switched to the new page, and
2125                          * "reuse" the old page writing into it while our pte
2126                          * here still points into it and can be read by other
2127                          * threads.
2128                          *
2129                          * The critical issue is to order this
2130                          * page_remove_rmap with the ptp_clear_flush above.
2131                          * Those stores are ordered by (if nothing else,)
2132                          * the barrier present in the atomic_add_negative
2133                          * in page_remove_rmap.
2134                          *
2135                          * Then the TLB flush in ptep_clear_flush ensures that
2136                          * no process can access the old page before the
2137                          * decremented mapcount is visible. And the old page
2138                          * cannot be reused until after the decremented
2139                          * mapcount is visible. So transitively, TLBs to
2140                          * old page will be flushed before it can be reused.
2141                          */
2142                         page_remove_rmap(old_page);
2143                 }
2144
2145                 /* Free the old page.. */
2146                 new_page = old_page;
2147                 ret |= VM_FAULT_WRITE;
2148         } else
2149                 mem_cgroup_uncharge_page(new_page);
2150
2151         if (new_page)
2152                 page_cache_release(new_page);
2153         if (old_page)
2154                 page_cache_release(old_page);
2155 unlock:
2156         pte_unmap_unlock(page_table, ptl);
2157         if (dirty_page) {
2158                 /*
2159                  * Yes, Virginia, this is actually required to prevent a race
2160                  * with clear_page_dirty_for_io() from clearing the page dirty
2161                  * bit after it clear all dirty ptes, but before a racing
2162                  * do_wp_page installs a dirty pte.
2163                  *
2164                  * do_no_page is protected similarly.
2165                  */
2166                 if (!page_mkwrite) {
2167                         wait_on_page_locked(dirty_page);
2168                         set_page_dirty_balance(dirty_page, page_mkwrite);
2169                 }
2170                 put_page(dirty_page);
2171                 if (page_mkwrite) {
2172                         struct address_space *mapping = dirty_page->mapping;
2173
2174                         set_page_dirty(dirty_page);
2175                         unlock_page(dirty_page);
2176                         page_cache_release(dirty_page);
2177                         if (mapping)    {
2178                                 /*
2179                                  * Some device drivers do not set page.mapping
2180                                  * but still dirty their pages
2181                                  */
2182                                 balance_dirty_pages_ratelimited(mapping);
2183                         }
2184                 }
2185
2186                 /* file_update_time outside page_lock */
2187                 if (vma->vm_file)
2188                         file_update_time(vma->vm_file);
2189         }
2190         return ret;
2191 oom_free_new:
2192         page_cache_release(new_page);
2193 oom:
2194         if (old_page) {
2195                 if (page_mkwrite) {
2196                         unlock_page(old_page);
2197                         page_cache_release(old_page);
2198                 }
2199                 page_cache_release(old_page);
2200         }
2201         return VM_FAULT_OOM;
2202
2203 unwritable_page:
2204         page_cache_release(old_page);
2205         return ret;
2206 }
2207
2208 /*
2209  * Helper functions for unmap_mapping_range().
2210  *
2211  * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
2212  *
2213  * We have to restart searching the prio_tree whenever we drop the lock,
2214  * since the iterator is only valid while the lock is held, and anyway
2215  * a later vma might be split and reinserted earlier while lock dropped.
2216  *
2217  * The list of nonlinear vmas could be handled more efficiently, using
2218  * a placeholder, but handle it in the same way until a need is shown.
2219  * It is important to search the prio_tree before nonlinear list: a vma
2220  * may become nonlinear and be shifted from prio_tree to nonlinear list
2221  * while the lock is dropped; but never shifted from list to prio_tree.
2222  *
2223  * In order to make forward progress despite restarting the search,
2224  * vm_truncate_count is used to mark a vma as now dealt with, so we can
2225  * quickly skip it next time around.  Since the prio_tree search only
2226  * shows us those vmas affected by unmapping the range in question, we
2227  * can't efficiently keep all vmas in step with mapping->truncate_count:
2228  * so instead reset them all whenever it wraps back to 0 (then go to 1).
2229  * mapping->truncate_count and vma->vm_truncate_count are protected by
2230  * i_mmap_lock.
2231  *
2232  * In order to make forward progress despite repeatedly restarting some
2233  * large vma, note the restart_addr from unmap_vmas when it breaks out:
2234  * and restart from that address when we reach that vma again.  It might
2235  * have been split or merged, shrunk or extended, but never shifted: so
2236  * restart_addr remains valid so long as it remains in the vma's range.
2237  * unmap_mapping_range forces truncate_count to leap over page-aligned
2238  * values so we can save vma's restart_addr in its truncate_count field.
2239  */
2240 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
2241
2242 static void reset_vma_truncate_counts(struct address_space *mapping)
2243 {
2244         struct vm_area_struct *vma;
2245         struct prio_tree_iter iter;
2246
2247         vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
2248                 vma->vm_truncate_count = 0;
2249         list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
2250                 vma->vm_truncate_count = 0;
2251 }
2252
2253 static int unmap_mapping_range_vma(struct vm_area_struct *vma,
2254                 unsigned long start_addr, unsigned long end_addr,
2255                 struct zap_details *details)
2256 {
2257         unsigned long restart_addr;
2258         int need_break;
2259
2260         /*
2261          * files that support invalidating or truncating portions of the
2262          * file from under mmaped areas must have their ->fault function
2263          * return a locked page (and set VM_FAULT_LOCKED in the return).
2264          * This provides synchronisation against concurrent unmapping here.
2265          */
2266
2267 again:
2268         restart_addr = vma->vm_truncate_count;
2269         if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
2270                 start_addr = restart_addr;
2271                 if (start_addr >= end_addr) {
2272                         /* Top of vma has been split off since last time */
2273                         vma->vm_truncate_count = details->truncate_count;
2274                         return 0;
2275                 }
2276         }
2277
2278         restart_addr = zap_page_range(vma, start_addr,
2279                                         end_addr - start_addr, details);
2280         need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
2281
2282         if (restart_addr >= end_addr) {
2283                 /* We have now completed this vma: mark it so */
2284                 vma->vm_truncate_count = details->truncate_count;
2285                 if (!need_break)
2286                         return 0;
2287         } else {
2288                 /* Note restart_addr in vma's truncate_count field */
2289                 vma->vm_truncate_count = restart_addr;
2290                 if (!need_break)
2291                         goto again;
2292         }
2293
2294         spin_unlock(details->i_mmap_lock);
2295         cond_resched();
2296         spin_lock(details->i_mmap_lock);
2297         return -EINTR;
2298 }
2299
2300 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
2301                                             struct zap_details *details)
2302 {
2303         struct vm_area_struct *vma;
2304         struct prio_tree_iter iter;
2305         pgoff_t vba, vea, zba, zea;
2306
2307 restart:
2308         vma_prio_tree_foreach(vma, &iter, root,
2309                         details->first_index, details->last_index) {
2310                 /* Skip quickly over those we have already dealt with */
2311                 if (vma->vm_truncate_count == details->truncate_count)
2312                         continue;
2313
2314                 vba = vma->vm_pgoff;
2315                 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
2316                 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2317                 zba = details->first_index;
2318                 if (zba < vba)
2319                         zba = vba;
2320                 zea = details->last_index;
2321                 if (zea > vea)
2322                         zea = vea;
2323
2324                 if (unmap_mapping_range_vma(vma,
2325                         ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2326                         ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2327                                 details) < 0)
2328                         goto restart;
2329         }
2330 }
2331
2332 static inline void unmap_mapping_range_list(struct list_head *head,
2333                                             struct zap_details *details)
2334 {
2335         struct vm_area_struct *vma;
2336
2337         /*
2338          * In nonlinear VMAs there is no correspondence between virtual address
2339          * offset and file offset.  So we must perform an exhaustive search
2340          * across *all* the pages in each nonlinear VMA, not just the pages
2341          * whose virtual address lies outside the file truncation point.
2342          */
2343 restart:
2344         list_for_each_entry(vma, head, shared.vm_set.list) {
2345                 /* Skip quickly over those we have already dealt with */
2346                 if (vma->vm_truncate_count == details->truncate_count)
2347                         continue;
2348                 details->nonlinear_vma = vma;
2349                 if (unmap_mapping_range_vma(vma, vma->vm_start,
2350                                         vma->vm_end, details) < 0)
2351                         goto restart;
2352         }
2353 }
2354
2355 /**
2356  * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2357  * @mapping: the address space containing mmaps to be unmapped.
2358  * @holebegin: byte in first page to unmap, relative to the start of
2359  * the underlying file.  This will be rounded down to a PAGE_SIZE
2360  * boundary.  Note that this is different from vmtruncate(), which
2361  * must keep the partial page.  In contrast, we must get rid of
2362  * partial pages.
2363  * @holelen: size of prospective hole in bytes.  This will be rounded
2364  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
2365  * end of the file.
2366  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2367  * but 0 when invalidating pagecache, don't throw away private data.
2368  */
2369 void unmap_mapping_range(struct address_space *mapping,
2370                 loff_t const holebegin, loff_t const holelen, int even_cows)
2371 {
2372         struct zap_details details;
2373         pgoff_t hba = holebegin >> PAGE_SHIFT;
2374         pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2375
2376         /* Check for overflow. */
2377         if (sizeof(holelen) > sizeof(hlen)) {
2378                 long long holeend =
2379                         (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2380                 if (holeend & ~(long long)ULONG_MAX)
2381                         hlen = ULONG_MAX - hba + 1;
2382         }
2383
2384         details.check_mapping = even_cows? NULL: mapping;
2385         details.nonlinear_vma = NULL;
2386         details.first_index = hba;
2387         details.last_index = hba + hlen - 1;
2388         if (details.last_index < details.first_index)
2389                 details.last_index = ULONG_MAX;
2390         details.i_mmap_lock = &mapping->i_mmap_lock;
2391
2392         spin_lock(&mapping->i_mmap_lock);
2393
2394         /* Protect against endless unmapping loops */
2395         mapping->truncate_count++;
2396         if (unlikely(is_restart_addr(mapping->truncate_count))) {
2397                 if (mapping->truncate_count == 0)
2398                         reset_vma_truncate_counts(mapping);
2399                 mapping->truncate_count++;
2400         }
2401         details.truncate_count = mapping->truncate_count;
2402
2403         if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
2404                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2405         if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2406                 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2407         spin_unlock(&mapping->i_mmap_lock);
2408 }
2409 EXPORT_SYMBOL(unmap_mapping_range);
2410
2411 /**
2412  * vmtruncate - unmap mappings "freed" by truncate() syscall
2413  * @inode: inode of the file used
2414  * @offset: file offset to start truncating
2415  *
2416  * NOTE! We have to be ready to update the memory sharing
2417  * between the file and the memory map for a potential last
2418  * incomplete page.  Ugly, but necessary.
2419  */
2420 int vmtruncate(struct inode * inode, loff_t offset)
2421 {
2422         if (inode->i_size < offset) {
2423                 unsigned long limit;
2424
2425                 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
2426                 if (limit != RLIM_INFINITY && offset > limit)
2427                         goto out_sig;
2428                 if (offset > inode->i_sb->s_maxbytes)
2429                         goto out_big;
2430                 i_size_write(inode, offset);
2431         } else {
2432                 struct address_space *mapping = inode->i_mapping;
2433
2434                 /*
2435                  * truncation of in-use swapfiles is disallowed - it would
2436                  * cause subsequent swapout to scribble on the now-freed
2437                  * blocks.
2438                  */
2439                 if (IS_SWAPFILE(inode))
2440                         return -ETXTBSY;
2441                 i_size_write(inode, offset);
2442
2443                 /*
2444                  * unmap_mapping_range is called twice, first simply for
2445                  * efficiency so that truncate_inode_pages does fewer
2446                  * single-page unmaps.  However after this first call, and
2447                  * before truncate_inode_pages finishes, it is possible for
2448                  * private pages to be COWed, which remain after
2449                  * truncate_inode_pages finishes, hence the second
2450                  * unmap_mapping_range call must be made for correctness.
2451                  */
2452                 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
2453                 truncate_inode_pages(mapping, offset);
2454                 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
2455         }
2456
2457         if (inode->i_op->truncate)
2458                 inode->i_op->truncate(inode);
2459         return 0;
2460
2461 out_sig:
2462         send_sig(SIGXFSZ, current, 0);
2463 out_big:
2464         return -EFBIG;
2465 }
2466 EXPORT_SYMBOL(vmtruncate);
2467
2468 int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
2469 {
2470         struct address_space *mapping = inode->i_mapping;
2471
2472         /*
2473          * If the underlying filesystem is not going to provide
2474          * a way to truncate a range of blocks (punch a hole) -
2475          * we should return failure right now.
2476          */
2477         if (!inode->i_op->truncate_range)
2478                 return -ENOSYS;
2479
2480         mutex_lock(&inode->i_mutex);
2481         down_write(&inode->i_alloc_sem);
2482         unmap_mapping_range(mapping, offset, (end - offset), 1);
2483         truncate_inode_pages_range(mapping, offset, end);
2484         unmap_mapping_range(mapping, offset, (end - offset), 1);
2485         inode->i_op->truncate_range(inode, offset, end);
2486         up_write(&inode->i_alloc_sem);
2487         mutex_unlock(&inode->i_mutex);
2488
2489         return 0;
2490 }
2491
2492 /*
2493  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2494  * but allow concurrent faults), and pte mapped but not yet locked.
2495  * We return with mmap_sem still held, but pte unmapped and unlocked.
2496  */
2497 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2498                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2499                 unsigned int flags, pte_t orig_pte)
2500 {
2501         spinlock_t *ptl;
2502         struct page *page;
2503         swp_entry_t entry;
2504         pte_t pte;
2505         struct mem_cgroup *ptr = NULL;
2506         int ret = 0;
2507
2508         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2509                 goto out;
2510
2511         entry = pte_to_swp_entry(orig_pte);
2512         if (is_migration_entry(entry)) {
2513                 migration_entry_wait(mm, pmd, address);
2514                 goto out;
2515         }
2516         delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2517         page = lookup_swap_cache(entry);
2518         if (!page) {
2519                 grab_swap_token(); /* Contend for token _before_ read-in */
2520                 page = swapin_readahead(entry,
2521                                         GFP_HIGHUSER_MOVABLE, vma, address);
2522                 if (!page) {
2523                         /*
2524                          * Back out if somebody else faulted in this pte
2525                          * while we released the pte lock.
2526                          */
2527                         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2528                         if (likely(pte_same(*page_table, orig_pte)))
2529                                 ret = VM_FAULT_OOM;
2530                         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2531                         goto unlock;
2532                 }
2533
2534                 /* Had to read the page from swap area: Major fault */
2535                 ret = VM_FAULT_MAJOR;
2536                 count_vm_event(PGMAJFAULT);
2537         }
2538
2539         lock_page(page);
2540         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2541
2542         if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2543                 ret = VM_FAULT_OOM;
2544                 goto out_page;
2545         }
2546
2547         /*
2548          * Back out if somebody else already faulted in this pte.
2549          */
2550         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2551         if (unlikely(!pte_same(*page_table, orig_pte)))
2552                 goto out_nomap;
2553
2554         if (unlikely(!PageUptodate(page))) {
2555                 ret = VM_FAULT_SIGBUS;
2556                 goto out_nomap;
2557         }
2558
2559         /*
2560          * The page isn't present yet, go ahead with the fault.
2561          *
2562          * Be careful about the sequence of operations here.
2563          * To get its accounting right, reuse_swap_page() must be called
2564          * while the page is counted on swap but not yet in mapcount i.e.
2565          * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2566          * must be called after the swap_free(), or it will never succeed.
2567          * Because delete_from_swap_page() may be called by reuse_swap_page(),
2568          * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
2569          * in page->private. In this case, a record in swap_cgroup  is silently
2570          * discarded at swap_free().
2571          */
2572
2573         inc_mm_counter(mm, anon_rss);
2574         pte = mk_pte(page, vma->vm_page_prot);
2575         if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
2576                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2577                 flags &= ~FAULT_FLAG_WRITE;
2578         }
2579         flush_icache_page(vma, page);
2580         set_pte_at(mm, address, page_table, pte);
2581         page_add_anon_rmap(page, vma, address);
2582         /* It's better to call commit-charge after rmap is established */
2583         mem_cgroup_commit_charge_swapin(page, ptr);
2584
2585         swap_free(entry);
2586         if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2587                 try_to_free_swap(page);
2588         unlock_page(page);
2589
2590         if (flags & FAULT_FLAG_WRITE) {
2591                 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
2592                 if (ret & VM_FAULT_ERROR)
2593                         ret &= VM_FAULT_ERROR;
2594                 goto out;
2595         }
2596
2597         /* No need to invalidate - it was non-present before */
2598         update_mmu_cache(vma, address, pte);
2599 unlock:
2600         pte_unmap_unlock(page_table, ptl);
2601 out:
2602         return ret;
2603 out_nomap:
2604         mem_cgroup_cancel_charge_swapin(ptr);
2605         pte_unmap_unlock(page_table, ptl);
2606 out_page:
2607         unlock_page(page);
2608         page_cache_release(page);
2609         return ret;
2610 }
2611
2612 /*
2613  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2614  * but allow concurrent faults), and pte mapped but not yet locked.
2615  * We return with mmap_sem still held, but pte unmapped and unlocked.
2616  */
2617 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
2618                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2619                 unsigned int flags)
2620 {
2621         struct page *page;
2622         spinlock_t *ptl;
2623         pte_t entry;
2624
2625         /* Allocate our own private page. */
2626         pte_unmap(page_table);
2627
2628         if (unlikely(anon_vma_prepare(vma)))
2629                 goto oom;
2630         page = alloc_zeroed_user_highpage_movable(vma, address);
2631         if (!page)
2632                 goto oom;
2633         __SetPageUptodate(page);
2634
2635         if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
2636                 goto oom_free_page;
2637
2638         entry = mk_pte(page, vma->vm_page_prot);
2639         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2640
2641         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2642         if (!pte_none(*page_table))
2643                 goto release;
2644         inc_mm_counter(mm, anon_rss);
2645         page_add_new_anon_rmap(page, vma, address);
2646         set_pte_at(mm, address, page_table, entry);
2647
2648         /* No need to invalidate - it was non-present before */
2649         update_mmu_cache(vma, address, entry);
2650 unlock:
2651         pte_unmap_unlock(page_table, ptl);
2652         return 0;
2653 release:
2654         mem_cgroup_uncharge_page(page);
2655         page_cache_release(page);
2656         goto unlock;
2657 oom_free_page:
2658         page_cache_release(page);
2659 oom:
2660         return VM_FAULT_OOM;
2661 }
2662
2663 /*
2664  * __do_fault() tries to create a new page mapping. It aggressively
2665  * tries to share with existing pages, but makes a separate copy if
2666  * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
2667  * the next page fault.
2668  *
2669  * As this is called only for pages that do not currently exist, we
2670  * do not need to flush old virtual caches or the TLB.
2671  *
2672  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2673  * but allow concurrent faults), and pte neither mapped nor locked.
2674  * We return with mmap_sem still held, but pte unmapped and unlocked.
2675  */
2676 static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2677                 unsigned long address, pmd_t *pmd,
2678                 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
2679 {
2680         pte_t *page_table;
2681         spinlock_t *ptl;
2682         struct page *page;
2683         pte_t entry;
2684         int anon = 0;
2685         int charged = 0;
2686         struct page *dirty_page = NULL;
2687         struct vm_fault vmf;
2688         int ret;
2689         int page_mkwrite = 0;
2690
2691         vmf.virtual_address = (void __user *)(address & PAGE_MASK);
2692         vmf.pgoff = pgoff;
2693         vmf.flags = flags;
2694         vmf.page = NULL;
2695
2696         ret = vma->vm_ops->fault(vma, &vmf);
2697         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2698                 return ret;
2699
2700         /*
2701          * For consistency in subsequent calls, make the faulted page always
2702          * locked.
2703          */
2704         if (unlikely(!(ret & VM_FAULT_LOCKED)))
2705                 lock_page(vmf.page);
2706         else
2707                 VM_BUG_ON(!PageLocked(vmf.page));
2708
2709         /*
2710          * Should we do an early C-O-W break?
2711          */
2712         page = vmf.page;
2713         if (flags & FAULT_FLAG_WRITE) {
2714                 if (!(vma->vm_flags & VM_SHARED)) {
2715                         anon = 1;
2716                         if (unlikely(anon_vma_prepare(vma))) {
2717                                 ret = VM_FAULT_OOM;
2718                                 goto out;
2719                         }
2720                         page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
2721                                                 vma, address);
2722                         if (!page) {
2723                                 ret = VM_FAULT_OOM;
2724                                 goto out;
2725                         }
2726                         if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
2727                                 ret = VM_FAULT_OOM;
2728                                 page_cache_release(page);
2729                                 goto out;
2730                         }
2731                         charged = 1;
2732                         /*
2733                          * Don't let another task, with possibly unlocked vma,
2734                          * keep the mlocked page.
2735                          */
2736                         if (vma->vm_flags & VM_LOCKED)
2737                                 clear_page_mlock(vmf.page);
2738                         copy_user_highpage(page, vmf.page, address, vma);
2739                         __SetPageUptodate(page);
2740                 } else {
2741                         /*
2742                          * If the page will be shareable, see if the backing
2743                          * address space wants to know that the page is about
2744                          * to become writable
2745                          */
2746                         if (vma->vm_ops->page_mkwrite) {
2747                                 int tmp;
2748
2749                                 unlock_page(page);
2750                                 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2751                                 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2752                                 if (unlikely(tmp &
2753                                           (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2754                                         ret = tmp;
2755                                         goto unwritable_page;
2756                                 }
2757                                 if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2758                                         lock_page(page);
2759                                         if (!page->mapping) {
2760                                                 ret = 0; /* retry the fault */
2761                                                 unlock_page(page);
2762                                                 goto unwritable_page;
2763                                         }
2764                                 } else
2765                                         VM_BUG_ON(!PageLocked(page));
2766                                 page_mkwrite = 1;
2767                         }
2768                 }
2769
2770         }
2771
2772         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2773
2774         /*
2775          * This silly early PAGE_DIRTY setting removes a race
2776          * due to the bad i386 page protection. But it's valid
2777          * for other architectures too.
2778          *
2779          * Note that if FAULT_FLAG_WRITE is set, we either now have
2780          * an exclusive copy of the page, or this is a shared mapping,
2781          * so we can make it writable and dirty to avoid having to
2782          * handle that later.
2783          */
2784         /* Only go through if we didn't race with anybody else... */
2785         if (likely(pte_same(*page_table, orig_pte))) {
2786                 flush_icache_page(vma, page);
2787                 entry = mk_pte(page, vma->vm_page_prot);
2788                 if (flags & FAULT_FLAG_WRITE)
2789                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2790                 if (anon) {
2791                         inc_mm_counter(mm, anon_rss);
2792                         page_add_new_anon_rmap(page, vma, address);
2793                 } else {
2794                         inc_mm_counter(mm, file_rss);
2795                         page_add_file_rmap(page);
2796                         if (flags & FAULT_FLAG_WRITE) {
2797                                 dirty_page = page;
2798                                 get_page(dirty_page);
2799                         }
2800                 }
2801                 set_pte_at(mm, address, page_table, entry);
2802
2803                 /* no need to invalidate: a not-present page won't be cached */
2804                 update_mmu_cache(vma, address, entry);
2805         } else {
2806                 if (charged)
2807                         mem_cgroup_uncharge_page(page);
2808                 if (anon)
2809                         page_cache_release(page);
2810                 else
2811                         anon = 1; /* no anon but release faulted_page */
2812         }
2813
2814         pte_unmap_unlock(page_table, ptl);
2815
2816 out:
2817         if (dirty_page) {
2818                 struct address_space *mapping = page->mapping;
2819
2820                 if (set_page_dirty(dirty_page))
2821                         page_mkwrite = 1;
2822                 unlock_page(dirty_page);
2823                 put_page(dirty_page);
2824                 if (page_mkwrite && mapping) {
2825                         /*
2826                          * Some device drivers do not set page.mapping but still
2827                          * dirty their pages
2828                          */
2829                         balance_dirty_pages_ratelimited(mapping);
2830                 }
2831
2832                 /* file_update_time outside page_lock */
2833                 if (vma->vm_file)
2834                         file_update_time(vma->vm_file);
2835         } else {
2836                 unlock_page(vmf.page);
2837                 if (anon)
2838                         page_cache_release(vmf.page);
2839         }
2840
2841         return ret;
2842
2843 unwritable_page:
2844         page_cache_release(page);
2845         return ret;
2846 }
2847
2848 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2849                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2850                 unsigned int flags, pte_t orig_pte)
2851 {
2852         pgoff_t pgoff = (((address & PAGE_MASK)
2853                         - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2854
2855         pte_unmap(page_table);
2856         return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2857 }
2858
2859 /*
2860  * Fault of a previously existing named mapping. Repopulate the pte
2861  * from the encoded file_pte if possible. This enables swappable
2862  * nonlinear vmas.
2863  *
2864  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2865  * but allow concurrent faults), and pte mapped but not yet locked.
2866  * We return with mmap_sem still held, but pte unmapped and unlocked.
2867  */
2868 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2869                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2870                 unsigned int flags, pte_t orig_pte)
2871 {
2872         pgoff_t pgoff;
2873
2874         flags |= FAULT_FLAG_NONLINEAR;
2875
2876         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2877                 return 0;
2878
2879         if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
2880                 /*
2881                  * Page table corrupted: show pte and kill process.
2882                  */
2883                 print_bad_pte(vma, address, orig_pte, NULL);
2884                 return VM_FAULT_OOM;
2885         }
2886
2887         pgoff = pte_to_pgoff(orig_pte);
2888         return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2889 }
2890
2891 /*
2892  * These routines also need to handle stuff like marking pages dirty
2893  * and/or accessed for architectures that don't do it in hardware (most
2894  * RISC architectures).  The early dirtying is also good on the i386.
2895  *
2896  * There is also a hook called "update_mmu_cache()" that architectures
2897  * with external mmu caches can use to update those (ie the Sparc or
2898  * PowerPC hashed page tables that act as extended TLBs).
2899  *
2900  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2901  * but allow concurrent faults), and pte mapped but not yet locked.
2902  * We return with mmap_sem still held, but pte unmapped and unlocked.
2903  */
2904 static inline int handle_pte_fault(struct mm_struct *mm,
2905                 struct vm_area_struct *vma, unsigned long address,
2906                 pte_t *pte, pmd_t *pmd, unsigned int flags)
2907 {
2908         pte_t entry;
2909         spinlock_t *ptl;
2910
2911         entry = *pte;
2912         if (!pte_present(entry)) {
2913                 if (pte_none(entry)) {
2914                         if (vma->vm_ops) {
2915                                 if (likely(vma->vm_ops->fault))
2916                                         return do_linear_fault(mm, vma, address,
2917                                                 pte, pmd, flags, entry);
2918                         }
2919                         return do_anonymous_page(mm, vma, address,
2920                                                  pte, pmd, flags);
2921                 }
2922                 if (pte_file(entry))
2923                         return do_nonlinear_fault(mm, vma, address,
2924                                         pte, pmd, flags, entry);
2925                 return do_swap_page(mm, vma, address,
2926                                         pte, pmd, flags, entry);
2927         }
2928
2929         ptl = pte_lockptr(mm, pmd);
2930         spin_lock(ptl);
2931         if (unlikely(!pte_same(*pte, entry)))
2932                 goto unlock;
2933         if (flags & FAULT_FLAG_WRITE) {
2934                 if (!pte_write(entry))
2935                         return do_wp_page(mm, vma, address,
2936                                         pte, pmd, ptl, entry);
2937                 entry = pte_mkdirty(entry);
2938         }
2939         entry = pte_mkyoung(entry);
2940         if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
2941                 update_mmu_cache(vma, address, entry);
2942         } else {
2943                 /*
2944                  * This is needed only for protection faults but the arch code
2945                  * is not yet telling us if this is a protection fault or not.
2946                  * This still avoids useless tlb flushes for .text page faults
2947                  * with threads.
2948                  */
2949                 if (flags & FAULT_FLAG_WRITE)
2950                         flush_tlb_page(vma, address);
2951         }
2952 unlock:
2953         pte_unmap_unlock(pte, ptl);
2954         return 0;
2955 }
2956
2957 /*
2958  * By the time we get here, we already hold the mm semaphore
2959  */
2960 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2961                 unsigned long address, int write_access)
2962 {
2963         pgd_t *pgd;
2964         pud_t *pud;
2965         pmd_t *pmd;
2966         pte_t *pte;
2967         unsigned int flags = write_access ? FAULT_FLAG_WRITE : 0;
2968
2969         __set_current_state(TASK_RUNNING);
2970
2971         count_vm_event(PGFAULT);
2972
2973         if (unlikely(is_vm_hugetlb_page(vma)))
2974                 return hugetlb_fault(mm, vma, address, flags);
2975
2976         pgd = pgd_offset(mm, address);
2977         pud = pud_alloc(mm, pgd, address);
2978         if (!pud)
2979                 return VM_FAULT_OOM;
2980         pmd = pmd_alloc(mm, pud, address);
2981         if (!pmd)
2982                 return VM_FAULT_OOM;
2983         pte = pte_alloc_map(mm, pmd, address);
2984         if (!pte)
2985                 return VM_FAULT_OOM;
2986
2987         return handle_pte_fault(mm, vma, address, pte, pmd, flags);
2988 }
2989
2990 #ifndef __PAGETABLE_PUD_FOLDED
2991 /*
2992  * Allocate page upper directory.
2993  * We've already handled the fast-path in-line.
2994  */
2995 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2996 {
2997         pud_t *new = pud_alloc_one(mm, address);
2998         if (!new)
2999                 return -ENOMEM;
3000
3001         smp_wmb(); /* See comment in __pte_alloc */
3002
3003         spin_lock(&mm->page_table_lock);
3004         if (pgd_present(*pgd))          /* Another has populated it */
3005                 pud_free(mm, new);
3006         else
3007                 pgd_populate(mm, pgd, new);
3008         spin_unlock(&mm->page_table_lock);
3009         return 0;
3010 }
3011 #endif /* __PAGETABLE_PUD_FOLDED */
3012
3013 #ifndef __PAGETABLE_PMD_FOLDED
3014 /*
3015  * Allocate page middle directory.
3016  * We've already handled the fast-path in-line.
3017  */
3018 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3019 {
3020         pmd_t *new = pmd_alloc_one(mm, address);
3021         if (!new)
3022                 return -ENOMEM;
3023
3024         smp_wmb(); /* See comment in __pte_alloc */
3025
3026         spin_lock(&mm->page_table_lock);
3027 #ifndef __ARCH_HAS_4LEVEL_HACK
3028         if (pud_present(*pud))          /* Another has populated it */
3029                 pmd_free(mm, new);
3030         else
3031                 pud_populate(mm, pud, new);
3032 #else
3033         if (pgd_present(*pud))          /* Another has populated it */
3034                 pmd_free(mm, new);
3035         else
3036                 pgd_populate(mm, pud, new);
3037 #endif /* __ARCH_HAS_4LEVEL_HACK */
3038         spin_unlock(&mm->page_table_lock);
3039         return 0;
3040 }
3041 #endif /* __PAGETABLE_PMD_FOLDED */
3042
3043 int make_pages_present(unsigned long addr, unsigned long end)
3044 {
3045         int ret, len, write;
3046         struct vm_area_struct * vma;
3047
3048         vma = find_vma(current->mm, addr);
3049         if (!vma)
3050                 return -ENOMEM;
3051         write = (vma->vm_flags & VM_WRITE) != 0;
3052         BUG_ON(addr >= end);
3053         BUG_ON(end > vma->vm_end);
3054         len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
3055         ret = get_user_pages(current, current->mm, addr,
3056                         len, write, 0, NULL, NULL);
3057         if (ret < 0)
3058                 return ret;
3059         return ret == len ? 0 : -EFAULT;
3060 }
3061
3062 #if !defined(__HAVE_ARCH_GATE_AREA)
3063
3064 #if defined(AT_SYSINFO_EHDR)
3065 static struct vm_area_struct gate_vma;
3066
3067 static int __init gate_vma_init(void)
3068 {
3069         gate_vma.vm_mm = NULL;
3070         gate_vma.vm_start = FIXADDR_USER_START;
3071         gate_vma.vm_end = FIXADDR_USER_END;
3072         gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
3073         gate_vma.vm_page_prot = __P101;
3074         /*
3075          * Make sure the vDSO gets into every core dump.
3076          * Dumping its contents makes post-mortem fully interpretable later
3077          * without matching up the same kernel and hardware config to see
3078          * what PC values meant.
3079          */
3080         gate_vma.vm_flags |= VM_ALWAYSDUMP;
3081         return 0;
3082 }
3083 __initcall(gate_vma_init);
3084 #endif
3085
3086 struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
3087 {
3088 #ifdef AT_SYSINFO_EHDR
3089         return &gate_vma;
3090 #else
3091         return NULL;
3092 #endif
3093 }
3094
3095 int in_gate_area_no_task(unsigned long addr)
3096 {
3097 #ifdef AT_SYSINFO_EHDR
3098         if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3099                 return 1;
3100 #endif
3101         return 0;
3102 }
3103
3104 #endif  /* __HAVE_ARCH_GATE_AREA */
3105
3106 static int follow_pte(struct mm_struct *mm, unsigned long address,
3107                 pte_t **ptepp, spinlock_t **ptlp)
3108 {
3109         pgd_t *pgd;
3110         pud_t *pud;
3111         pmd_t *pmd;
3112         pte_t *ptep;
3113
3114         pgd = pgd_offset(mm, address);
3115         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3116                 goto out;
3117
3118         pud = pud_offset(pgd, address);
3119         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3120                 goto out;
3121
3122         pmd = pmd_offset(pud, address);
3123         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3124                 goto out;
3125
3126         /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3127         if (pmd_huge(*pmd))
3128                 goto out;
3129
3130         ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3131         if (!ptep)
3132                 goto out;
3133         if (!pte_present(*ptep))
3134                 goto unlock;
3135         *ptepp = ptep;
3136         return 0;
3137 unlock:
3138         pte_unmap_unlock(ptep, *ptlp);
3139 out:
3140         return -EINVAL;
3141 }
3142
3143 /**
3144  * follow_pfn - look up PFN at a user virtual address
3145  * @vma: memory mapping
3146  * @address: user virtual address
3147  * @pfn: location to store found PFN
3148  *
3149  * Only IO mappings and raw PFN mappings are allowed.
3150  *
3151  * Returns zero and the pfn at @pfn on success, -ve otherwise.
3152  */
3153 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3154         unsigned long *pfn)
3155 {
3156         int ret = -EINVAL;
3157         spinlock_t *ptl;
3158         pte_t *ptep;
3159
3160         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3161                 return ret;
3162
3163         ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3164         if (ret)
3165                 return ret;
3166         *pfn = pte_pfn(*ptep);
3167         pte_unmap_unlock(ptep, ptl);
3168         return 0;
3169 }
3170 EXPORT_SYMBOL(follow_pfn);
3171
3172 #ifdef CONFIG_HAVE_IOREMAP_PROT
3173 int follow_phys(struct vm_area_struct *vma,
3174                 unsigned long address, unsigned int flags,
3175                 unsigned long *prot, resource_size_t *phys)
3176 {
3177         int ret = -EINVAL;
3178         pte_t *ptep, pte;
3179         spinlock_t *ptl;
3180
3181         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3182                 goto out;
3183
3184         if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3185                 goto out;
3186         pte = *ptep;
3187
3188         if ((flags & FOLL_WRITE) && !pte_write(pte))
3189                 goto unlock;
3190
3191         *prot = pgprot_val(pte_pgprot(pte));
3192         *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3193
3194         ret = 0;
3195 unlock:
3196         pte_unmap_unlock(ptep, ptl);
3197 out:
3198         return ret;
3199 }
3200
3201 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3202                         void *buf, int len, int write)
3203 {
3204         resource_size_t phys_addr;
3205         unsigned long prot = 0;
3206         void __iomem *maddr;
3207         int offset = addr & (PAGE_SIZE-1);
3208
3209         if (follow_phys(vma, addr, write, &prot, &phys_addr))
3210                 return -EINVAL;
3211
3212         maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
3213         if (write)
3214                 memcpy_toio(maddr + offset, buf, len);
3215         else
3216                 memcpy_fromio(buf, maddr + offset, len);
3217         iounmap(maddr);
3218
3219         return len;
3220 }
3221 #endif
3222
3223 /*
3224  * Access another process' address space.
3225  * Source/target buffer must be kernel space,
3226  * Do not walk the page table directly, use get_user_pages
3227  */
3228 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
3229 {
3230         struct mm_struct *mm;
3231         struct vm_area_struct *vma;
3232         void *old_buf = buf;
3233
3234         mm = get_task_mm(tsk);
3235         if (!mm)
3236                 return 0;
3237
3238         down_read(&mm->mmap_sem);
3239         /* ignore errors, just check how much was successfully transferred */
3240         while (len) {
3241                 int bytes, ret, offset;
3242                 void *maddr;
3243                 struct page *page = NULL;
3244
3245                 ret = get_user_pages(tsk, mm, addr, 1,
3246                                 write, 1, &page, &vma);
3247                 if (ret <= 0) {
3248                         /*
3249                          * Check if this is a VM_IO | VM_PFNMAP VMA, which
3250                          * we can access using slightly different code.
3251                          */
3252 #ifdef CONFIG_HAVE_IOREMAP_PROT
3253                         vma = find_vma(mm, addr);
3254                         if (!vma)
3255                                 break;
3256                         if (vma->vm_ops && vma->vm_ops->access)
3257                                 ret = vma->vm_ops->access(vma, addr, buf,
3258                                                           len, write);
3259                         if (ret <= 0)
3260 #endif
3261                                 break;
3262                         bytes = ret;
3263                 } else {
3264                         bytes = len;
3265                         offset = addr & (PAGE_SIZE-1);
3266                         if (bytes > PAGE_SIZE-offset)
3267                                 bytes = PAGE_SIZE-offset;
3268
3269                         maddr = kmap(page);
3270                         if (write) {
3271                                 copy_to_user_page(vma, page, addr,
3272                                                   maddr + offset, buf, bytes);
3273                                 set_page_dirty_lock(page);
3274                         } else {
3275                                 copy_from_user_page(vma, page, addr,
3276                                                     buf, maddr + offset, bytes);
3277                         }
3278                         kunmap(page);
3279                         page_cache_release(page);
3280                 }
3281                 len -= bytes;
3282                 buf += bytes;
3283                 addr += bytes;
3284         }
3285         up_read(&mm->mmap_sem);
3286         mmput(mm);
3287
3288         return buf - old_buf;
3289 }
3290
3291 /*
3292  * Print the name of a VMA.
3293  */
3294 void print_vma_addr(char *prefix, unsigned long ip)
3295 {
3296         struct mm_struct *mm = current->mm;
3297         struct vm_area_struct *vma;
3298
3299         /*
3300          * Do not print if we are in atomic
3301          * contexts (in exception stacks, etc.):
3302          */
3303         if (preempt_count())
3304                 return;
3305
3306         down_read(&mm->mmap_sem);
3307         vma = find_vma(mm, ip);
3308         if (vma && vma->vm_file) {
3309                 struct file *f = vma->vm_file;
3310                 char *buf = (char *)__get_free_page(GFP_KERNEL);
3311                 if (buf) {
3312                         char *p, *s;
3313
3314                         p = d_path(&f->f_path, buf, PAGE_SIZE);
3315                         if (IS_ERR(p))
3316                                 p = "?";
3317                         s = strrchr(p, '/');
3318                         if (s)
3319                                 p = s+1;
3320                         printk("%s%s[%lx+%lx]", prefix, p,
3321                                         vma->vm_start,
3322                                         vma->vm_end - vma->vm_start);
3323                         free_page((unsigned long)buf);
3324                 }
3325         }
3326         up_read(&current->mm->mmap_sem);
3327 }
3328
3329 #ifdef CONFIG_PROVE_LOCKING
3330 void might_fault(void)
3331 {
3332         /*
3333          * Some code (nfs/sunrpc) uses socket ops on kernel memory while
3334          * holding the mmap_sem, this is safe because kernel memory doesn't
3335          * get paged out, therefore we'll never actually fault, and the
3336          * below annotations will generate false positives.
3337          */
3338         if (segment_eq(get_fs(), KERNEL_DS))
3339                 return;
3340
3341         might_sleep();
3342         /*
3343          * it would be nicer only to annotate paths which are not under
3344          * pagefault_disable, however that requires a larger audit and
3345          * providing helpers like get_user_atomic.
3346          */
3347         if (!in_atomic() && current->mm)
3348                 might_lock_read(&current->mm->mmap_sem);
3349 }
3350 EXPORT_SYMBOL(might_fault);
3351 #endif