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
55 #include <asm/pgalloc.h>
56 #include <asm/uaccess.h>
57 #include <asm/tlb.h>
58 #include <asm/tlbflush.h>
59 #include <asm/pgtable.h>
60
61 #include <linux/swapops.h>
62 #include <linux/elf.h>
63
64 #ifndef CONFIG_NEED_MULTIPLE_NODES
65 /* use the per-pgdat data instead for discontigmem - mbligh */
66 unsigned long max_mapnr;
67 struct page *mem_map;
68
69 EXPORT_SYMBOL(max_mapnr);
70 EXPORT_SYMBOL(mem_map);
71 #endif
72
73 unsigned long num_physpages;
74 /*
75 * A number of key systems in x86 including ioremap() rely on the assumption
76 * that high_memory defines the upper bound on direct map memory, then end
77 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
78 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
79 * and ZONE_HIGHMEM.
80 */
81 void * high_memory;
82
83 EXPORT_SYMBOL(num_physpages);
84 EXPORT_SYMBOL(high_memory);
85
86 /*
87 * Randomize the address space (stacks, mmaps, brk, etc.).
88 *
89 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
90 * as ancient (libc5 based) binaries can segfault. )
91 */
92 int randomize_va_space __read_mostly =
93 #ifdef CONFIG_COMPAT_BRK
94 1;
95 #else
96 2;
97 #endif
98
99 static int __init disable_randmaps(char *s)
100 {
101 randomize_va_space = 0;
102 return 1;
103 }
104 __setup("norandmaps", disable_randmaps);
105
106
107 /*
108 * If a p?d_bad entry is found while walking page tables, report
109 * the error, before resetting entry to p?d_none. Usually (but
110 * very seldom) called out from the p?d_none_or_clear_bad macros.
111 */
112
113 void pgd_clear_bad(pgd_t *pgd)
114 {
115 pgd_ERROR(*pgd);
116 pgd_clear(pgd);
117 }
118
119 void pud_clear_bad(pud_t *pud)
120 {
121 pud_ERROR(*pud);
122 pud_clear(pud);
123 }
124
125 void pmd_clear_bad(pmd_t *pmd)
126 {
127 pmd_ERROR(*pmd);
128 pmd_clear(pmd);
129 }
130
131 /*
132 * Note: this doesn't free the actual pages themselves. That
133 * has been handled earlier when unmapping all the memory regions.
134 */
135 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
136 {
137 pgtable_t token = pmd_pgtable(*pmd);
138 pmd_clear(pmd);
139 pte_free_tlb(tlb, token);
140 tlb->mm->nr_ptes--;
141 }
142
143 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
144 unsigned long addr, unsigned long end,
145 unsigned long floor, unsigned long ceiling)
146 {
147 pmd_t *pmd;
148 unsigned long next;
149 unsigned long start;
150
151 start = addr;
152 pmd = pmd_offset(pud, addr);
153 do {
154 next = pmd_addr_end(addr, end);
155 if (pmd_none_or_clear_bad(pmd))
156 continue;
157 free_pte_range(tlb, pmd);
158 } while (pmd++, addr = next, addr != end);
159
160 start &= PUD_MASK;
161 if (start < floor)
162 return;
163 if (ceiling) {
164 ceiling &= PUD_MASK;
165 if (!ceiling)
166 return;
167 }
168 if (end - 1 > ceiling - 1)
169 return;
170
171 pmd = pmd_offset(pud, start);
172 pud_clear(pud);
173 pmd_free_tlb(tlb, pmd);
174 }
175
176 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
177 unsigned long addr, unsigned long end,
178 unsigned long floor, unsigned long ceiling)
179 {
180 pud_t *pud;
181 unsigned long next;
182 unsigned long start;
183
184 start = addr;
185 pud = pud_offset(pgd, addr);
186 do {
187 next = pud_addr_end(addr, end);
188 if (pud_none_or_clear_bad(pud))
189 continue;
190 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
191 } while (pud++, addr = next, addr != end);
192
193 start &= PGDIR_MASK;
194 if (start < floor)
195 return;
196 if (ceiling) {
197 ceiling &= PGDIR_MASK;
198 if (!ceiling)
199 return;
200 }
201 if (end - 1 > ceiling - 1)
202 return;
203
204 pud = pud_offset(pgd, start);
205 pgd_clear(pgd);
206 pud_free_tlb(tlb, pud);
207 }
208
209 /*
210 * This function frees user-level page tables of a process.
211 *
212 * Must be called with pagetable lock held.
213 */
214 void free_pgd_range(struct mmu_gather **tlb,
215 unsigned long addr, unsigned long end,
216 unsigned long floor, unsigned long ceiling)
217 {
218 pgd_t *pgd;
219 unsigned long next;
220 unsigned long start;
221
222 /*
223 * The next few lines have given us lots of grief...
224 *
225 * Why are we testing PMD* at this top level? Because often
226 * there will be no work to do at all, and we'd prefer not to
227 * go all the way down to the bottom just to discover that.
228 *
229 * Why all these "- 1"s? Because 0 represents both the bottom
230 * of the address space and the top of it (using -1 for the
231 * top wouldn't help much: the masks would do the wrong thing).
232 * The rule is that addr 0 and floor 0 refer to the bottom of
233 * the address space, but end 0 and ceiling 0 refer to the top
234 * Comparisons need to use "end - 1" and "ceiling - 1" (though
235 * that end 0 case should be mythical).
236 *
237 * Wherever addr is brought up or ceiling brought down, we must
238 * be careful to reject "the opposite 0" before it confuses the
239 * subsequent tests. But what about where end is brought down
240 * by PMD_SIZE below? no, end can't go down to 0 there.
241 *
242 * Whereas we round start (addr) and ceiling down, by different
243 * masks at different levels, in order to test whether a table
244 * now has no other vmas using it, so can be freed, we don't
245 * bother to round floor or end up - the tests don't need that.
246 */
247
248 addr &= PMD_MASK;
249 if (addr < floor) {
250 addr += PMD_SIZE;
251 if (!addr)
252 return;
253 }
254 if (ceiling) {
255 ceiling &= PMD_MASK;
256 if (!ceiling)
257 return;
258 }
259 if (end - 1 > ceiling - 1)
260 end -= PMD_SIZE;
261 if (addr > end - 1)
262 return;
263
264 start = addr;
265 pgd = pgd_offset((*tlb)->mm, addr);
266 do {
267 next = pgd_addr_end(addr, end);
268 if (pgd_none_or_clear_bad(pgd))
269 continue;
270 free_pud_range(*tlb, pgd, addr, next, floor, ceiling);
271 } while (pgd++, addr = next, addr != end);
272 }
273
274 #ifdef CONFIG_IA64
275 #define tlb_start_addr(tlb) (tlb)->start_addr
276 #define tlb_end_addr(tlb) (tlb)->end_addr
277 #else
278 #define tlb_start_addr(tlb) 0UL /* only ia64 really uses it */
279 #define tlb_end_addr(tlb) 0UL /* only ia64 really uses it */
280 #endif
281
282 void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
283 unsigned long floor, unsigned long ceiling)
284 {
285 #ifdef CONFIG_PREEMPT
286 struct vm_area_struct *unlink = vma;
287 int fullmm = (*tlb)->fullmm;
288
289 if (!vma) /* Sometimes when exiting after an oops */
290 return;
291 #ifndef CONFIG_PREEMPT_RT
292 if (vma->vm_next)
293 #endif
294 tlb_finish_mmu(*tlb, tlb_start_addr(*tlb), tlb_end_addr(*tlb));
295 /*
296 * Hide vma from rmap and vmtruncate before freeeing pgtables,
297 * with preemption enabled, except when unmapping just one area.
298 */
299 while (unlink) {
300 anon_vma_unlink(unlink);
301 unlink_file_vma(unlink);
302 unlink = unlink->vm_next;
303 }
304 #ifndef CONFIG_PREEMPT_RT
305 if (vma->vm_next)
306 #endif
307 *tlb = tlb_gather_mmu(vma->vm_mm, fullmm);
308 #endif
309 while (vma) {
310 struct vm_area_struct *next = vma->vm_next;
311 unsigned long addr = vma->vm_start;
312
313 #ifndef CONFIG_PREEMPT
314 /*
315 * Hide vma from rmap and vmtruncate before freeing pgtables
316 */
317 anon_vma_unlink(vma);
318 unlink_file_vma(vma);
319 #endif
320
321 if (is_vm_hugetlb_page(vma)) {
322 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
323 floor, next? next->vm_start: ceiling);
324 } else {
325 /*
326 * Optimization: gather nearby vmas into one call down
327 */
328 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
329 && !is_vm_hugetlb_page(next)) {
330 vma = next;
331 next = vma->vm_next;
332 #ifndef CONFIG_PREEMPT
333 anon_vma_unlink(vma);
334 unlink_file_vma(vma);
335 #endif
336 }
337 free_pgd_range(tlb, addr, vma->vm_end,
338 floor, next? next->vm_start: ceiling);
339 }
340 vma = next;
341 }
342 }
343
344 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
345 {
346 pgtable_t new = pte_alloc_one(mm, address);
347 if (!new)
348 return -ENOMEM;
349
350 spin_lock(&mm->page_table_lock);
351 if (!pmd_present(*pmd)) { /* Has another populated it ? */
352 mm->nr_ptes++;
353 pmd_populate(mm, pmd, new);
354 new = NULL;
355 }
356 spin_unlock(&mm->page_table_lock);
357 if (new)
358 pte_free(mm, new);
359 return 0;
360 }
361
362 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
363 {
364 pte_t *new = pte_alloc_one_kernel(&init_mm, address);
365 if (!new)
366 return -ENOMEM;
367
368 spin_lock(&init_mm.page_table_lock);
369 if (!pmd_present(*pmd)) { /* Has another populated it ? */
370 pmd_populate_kernel(&init_mm, pmd, new);
371 new = NULL;
372 }
373 spin_unlock(&init_mm.page_table_lock);
374 if (new)
375 pte_free_kernel(&init_mm, new);
376 return 0;
377 }
378
379 static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
380 {
381 if (file_rss)
382 add_mm_counter(mm, file_rss, file_rss);
383 if (anon_rss)
384 add_mm_counter(mm, anon_rss, anon_rss);
385 }
386
387 /*
388 * This function is called to print an error when a bad pte
389 * is found. For example, we might have a PFN-mapped pte in
390 * a region that doesn't allow it.
391 *
392 * The calling function must still handle the error.
393 */
394 void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr)
395 {
396 printk(KERN_ERR "Bad pte = %08llx, process = %s, "
397 "vm_flags = %lx, vaddr = %lx\n",
398 (long long)pte_val(pte),
399 (vma->vm_mm == current->mm ? current->comm : "???"),
400 vma->vm_flags, vaddr);
401 dump_stack();
402 }
403
404 static inline int is_cow_mapping(unsigned int flags)
405 {
406 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
407 }
408
409 /*
410 * This function gets the "struct page" associated with a pte.
411 *
412 * NOTE! Some mappings do not have "struct pages". A raw PFN mapping
413 * will have each page table entry just pointing to a raw page frame
414 * number, and as far as the VM layer is concerned, those do not have
415 * pages associated with them - even if the PFN might point to memory
416 * that otherwise is perfectly fine and has a "struct page".
417 *
418 * The way we recognize those mappings is through the rules set up
419 * by "remap_pfn_range()": the vma will have the VM_PFNMAP bit set,
420 * and the vm_pgoff will point to the first PFN mapped: thus every
421 * page that is a raw mapping will always honor the rule
422 *
423 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
424 *
425 * and if that isn't true, the page has been COW'ed (in which case it
426 * _does_ have a "struct page" associated with it even if it is in a
427 * VM_PFNMAP range).
428 */
429 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
430 {
431 unsigned long pfn = pte_pfn(pte);
432
433 if (unlikely(vma->vm_flags & VM_PFNMAP)) {
434 unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT;
435 if (pfn == vma->vm_pgoff + off)
436 return NULL;
437 if (!is_cow_mapping(vma->vm_flags))
438 return NULL;
439 }
440
441 #ifdef CONFIG_DEBUG_VM
442 /*
443 * Add some anal sanity checks for now. Eventually,
444 * we should just do "return pfn_to_page(pfn)", but
445 * in the meantime we check that we get a valid pfn,
446 * and that the resulting page looks ok.
447 */
448 if (unlikely(!pfn_valid(pfn))) {
449 print_bad_pte(vma, pte, addr);
450 return NULL;
451 }
452 #endif
453
454 /*
455 * NOTE! We still have PageReserved() pages in the page
456 * tables.
457 *
458 * The PAGE_ZERO() pages and various VDSO mappings can
459 * cause them to exist.
460 */
461 return pfn_to_page(pfn);
462 }
463
464 /*
465 * copy one vm_area from one task to the other. Assumes the page tables
466 * already present in the new task to be cleared in the whole range
467 * covered by this vma.
468 */
469
470 static inline void
471 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
472 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
473 unsigned long addr, int *rss)
474 {
475 unsigned long vm_flags = vma->vm_flags;
476 pte_t pte = *src_pte;
477 struct page *page;
478
479 /* pte contains position in swap or file, so copy. */
480 if (unlikely(!pte_present(pte))) {
481 if (!pte_file(pte)) {
482 swp_entry_t entry = pte_to_swp_entry(pte);
483
484 swap_duplicate(entry);
485 /* make sure dst_mm is on swapoff's mmlist. */
486 if (unlikely(list_empty(&dst_mm->mmlist))) {
487 spin_lock(&mmlist_lock);
488 if (list_empty(&dst_mm->mmlist))
489 list_add(&dst_mm->mmlist,
490 &src_mm->mmlist);
491 spin_unlock(&mmlist_lock);
492 }
493 if (is_write_migration_entry(entry) &&
494 is_cow_mapping(vm_flags)) {
495 /*
496 * COW mappings require pages in both parent
497 * and child to be set to read.
498 */
499 make_migration_entry_read(&entry);
500 pte = swp_entry_to_pte(entry);
501 set_pte_at(src_mm, addr, src_pte, pte);
502 }
503 }
504 goto out_set_pte;
505 }
506
507 /*
508 * If it's a COW mapping, write protect it both
509 * in the parent and the child
510 */
511 if (is_cow_mapping(vm_flags)) {
512 ptep_set_wrprotect(src_mm, addr, src_pte);
513 pte = pte_wrprotect(pte);
514 }
515
516 /*
517 * If it's a shared mapping, mark it clean in
518 * the child
519 */
520 if (vm_flags & VM_SHARED)
521 pte = pte_mkclean(pte);
522 pte = pte_mkold(pte);
523
524 page = vm_normal_page(vma, addr, pte);
525 if (page) {
526 get_page(page);
527 page_dup_rmap(page, vma, addr);
528 rss[!!PageAnon(page)]++;
529 }
530
531 out_set_pte:
532 set_pte_at(dst_mm, addr, dst_pte, pte);
533 }
534
535 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
536 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
537 unsigned long addr, unsigned long end)
538 {
539 pte_t *src_pte, *dst_pte;
540 spinlock_t *src_ptl, *dst_ptl;
541 int progress = 0;
542 int rss[2];
543
544 again:
545 rss[1] = rss[0] = 0;
546 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
547 if (!dst_pte)
548 return -ENOMEM;
549 src_pte = pte_offset_map_nested(src_pmd, addr);
550 src_ptl = pte_lockptr(src_mm, src_pmd);
551 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
552 arch_enter_lazy_mmu_mode();
553
554 do {
555 /*
556 * We are holding two locks at this point - either of them
557 * could generate latencies in another task on another CPU.
558 */
559 if (progress >= 32) {
560 progress = 0;
561 if (need_resched() ||
562 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
563 break;
564 }
565 if (pte_none(*src_pte)) {
566 progress++;
567 continue;
568 }
569 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
570 progress += 8;
571 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
572
573 arch_leave_lazy_mmu_mode();
574 spin_unlock(src_ptl);
575 pte_unmap_nested(src_pte - 1);
576 add_mm_rss(dst_mm, rss[0], rss[1]);
577 pte_unmap_unlock(dst_pte - 1, dst_ptl);
578 cond_resched();
579 if (addr != end)
580 goto again;
581 return 0;
582 }
583
584 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
585 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
586 unsigned long addr, unsigned long end)
587 {
588 pmd_t *src_pmd, *dst_pmd;
589 unsigned long next;
590
591 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
592 if (!dst_pmd)
593 return -ENOMEM;
594 src_pmd = pmd_offset(src_pud, addr);
595 do {
596 next = pmd_addr_end(addr, end);
597 if (pmd_none_or_clear_bad(src_pmd))
598 continue;
599 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
600 vma, addr, next))
601 return -ENOMEM;
602 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
603 return 0;
604 }
605
606 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
607 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
608 unsigned long addr, unsigned long end)
609 {
610 pud_t *src_pud, *dst_pud;
611 unsigned long next;
612
613 dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
614 if (!dst_pud)
615 return -ENOMEM;
616 src_pud = pud_offset(src_pgd, addr);
617 do {
618 next = pud_addr_end(addr, end);
619 if (pud_none_or_clear_bad(src_pud))
620 continue;
621 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
622 vma, addr, next))
623 return -ENOMEM;
624 } while (dst_pud++, src_pud++, addr = next, addr != end);
625 return 0;
626 }
627
628 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
629 struct vm_area_struct *vma)
630 {
631 pgd_t *src_pgd, *dst_pgd;
632 unsigned long next;
633 unsigned long addr = vma->vm_start;
634 unsigned long end = vma->vm_end;
635
636 /*
637 * Don't copy ptes where a page fault will fill them correctly.
638 * Fork becomes much lighter when there are big shared or private
639 * readonly mappings. The tradeoff is that copy_page_range is more
640 * efficient than faulting.
641 */
642 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
643 if (!vma->anon_vma)
644 return 0;
645 }
646
647 if (is_vm_hugetlb_page(vma))
648 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
649
650 dst_pgd = pgd_offset(dst_mm, addr);
651 src_pgd = pgd_offset(src_mm, addr);
652 do {
653 next = pgd_addr_end(addr, end);
654 if (pgd_none_or_clear_bad(src_pgd))
655 continue;
656 if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
657 vma, addr, next))
658 return -ENOMEM;
659 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
660 return 0;
661 }
662
663 static unsigned long zap_pte_range(struct mmu_gather *tlb,
664 struct vm_area_struct *vma, pmd_t *pmd,
665 unsigned long addr, unsigned long end,
666 long *zap_work, struct zap_details *details)
667 {
668 struct mm_struct *mm = tlb->mm;
669 pte_t *pte;
670 spinlock_t *ptl;
671 int file_rss = 0;
672 int anon_rss = 0;
673
674 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
675 arch_enter_lazy_mmu_mode();
676 do {
677 pte_t ptent = *pte;
678 if (pte_none(ptent)) {
679 (*zap_work)--;
680 continue;
681 }
682
683 (*zap_work) -= PAGE_SIZE;
684
685 if (pte_present(ptent)) {
686 struct page *page;
687
688 page = vm_normal_page(vma, addr, ptent);
689 if (unlikely(details) && page) {
690 /*
691 * unmap_shared_mapping_pages() wants to
692 * invalidate cache without truncating:
693 * unmap shared but keep private pages.
694 */
695 if (details->check_mapping &&
696 details->check_mapping != page->mapping)
697 continue;
698 /*
699 * Each page->index must be checked when
700 * invalidating or truncating nonlinear.
701 */
702 if (details->nonlinear_vma &&
703 (page->index < details->first_index ||
704 page->index > details->last_index))
705 continue;
706 }
707 ptent = ptep_get_and_clear_full(mm, addr, pte,
708 tlb->fullmm);
709 tlb_remove_tlb_entry(tlb, pte, addr);
710 if (unlikely(!page))
711 continue;
712 if (unlikely(details) && details->nonlinear_vma
713 && linear_page_index(details->nonlinear_vma,
714 addr) != page->index)
715 set_pte_at(mm, addr, pte,
716 pgoff_to_pte(page->index));
717 if (PageAnon(page))
718 anon_rss--;
719 else {
720 if (pte_dirty(ptent))
721 set_page_dirty(page);
722 if (pte_young(ptent))
723 SetPageReferenced(page);
724 file_rss--;
725 }
726 page_remove_rmap(page, vma);
727 tlb_remove_page(tlb, page);
728 continue;
729 }
730 /*
731 * If details->check_mapping, we leave swap entries;
732 * if details->nonlinear_vma, we leave file entries.
733 */
734 if (unlikely(details))
735 continue;
736 if (!pte_file(ptent))
737 free_swap_and_cache(pte_to_swp_entry(ptent));
738 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
739 } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
740
741 add_mm_rss(mm, file_rss, anon_rss);
742 arch_leave_lazy_mmu_mode();
743 pte_unmap_unlock(pte - 1, ptl);
744
745 return addr;
746 }
747
748 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
749 struct vm_area_struct *vma, pud_t *pud,
750 unsigned long addr, unsigned long end,
751 long *zap_work, struct zap_details *details)
752 {
753 pmd_t *pmd;
754 unsigned long next;
755
756 pmd = pmd_offset(pud, addr);
757 do {
758 next = pmd_addr_end(addr, end);
759 if (pmd_none_or_clear_bad(pmd)) {
760 (*zap_work)--;
761 continue;
762 }
763 next = zap_pte_range(tlb, vma, pmd, addr, next,
764 zap_work, details);
765 } while (pmd++, addr = next, (addr != end && *zap_work > 0));
766
767 return addr;
768 }
769
770 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
771 struct vm_area_struct *vma, pgd_t *pgd,
772 unsigned long addr, unsigned long end,
773 long *zap_work, struct zap_details *details)
774 {
775 pud_t *pud;
776 unsigned long next;
777
778 pud = pud_offset(pgd, addr);
779 do {
780 next = pud_addr_end(addr, end);
781 if (pud_none_or_clear_bad(pud)) {
782 (*zap_work)--;
783 continue;
784 }
785 next = zap_pmd_range(tlb, vma, pud, addr, next,
786 zap_work, details);
787 } while (pud++, addr = next, (addr != end && *zap_work > 0));
788
789 return addr;
790 }
791
792 static unsigned long unmap_page_range(struct mmu_gather *tlb,
793 struct vm_area_struct *vma,
794 unsigned long addr, unsigned long end,
795 long *zap_work, struct zap_details *details)
796 {
797 pgd_t *pgd;
798 unsigned long next;
799
800 if (details && !details->check_mapping && !details->nonlinear_vma)
801 details = NULL;
802
803 BUG_ON(addr >= end);
804 tlb_start_vma(tlb, vma);
805 pgd = pgd_offset(vma->vm_mm, addr);
806 do {
807 next = pgd_addr_end(addr, end);
808 if (pgd_none_or_clear_bad(pgd)) {
809 (*zap_work)--;
810 continue;
811 }
812 next = zap_pud_range(tlb, vma, pgd, addr, next,
813 zap_work, details);
814 } while (pgd++, addr = next, (addr != end && *zap_work > 0));
815 tlb_end_vma(tlb, vma);
816
817 return addr;
818 }
819
820 #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_RT)
821 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
822 #else
823 /*
824 * No preempt: go for improved straight-line efficiency
825 * on PREEMPT_RT this is not a critical latency-path.
826 */
827 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
828 #endif
829
830 /**
831 * unmap_vmas - unmap a range of memory covered by a list of vma's
832 * @tlbp: address of the caller's struct mmu_gather
833 * @vma: the starting vma
834 * @start_addr: virtual address at which to start unmapping
835 * @end_addr: virtual address at which to end unmapping
836 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
837 * @details: details of nonlinear truncation or shared cache invalidation
838 *
839 * Returns the end address of the unmapping (restart addr if interrupted).
840 *
841 * Unmap all pages in the vma list.
842 *
843 * We aim to not hold locks for too long (for scheduling latency reasons).
844 * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to
845 * return the ending mmu_gather to the caller.
846 *
847 * Only addresses between `start' and `end' will be unmapped.
848 *
849 * The VMA list must be sorted in ascending virtual address order.
850 *
851 * unmap_vmas() assumes that the caller will flush the whole unmapped address
852 * range after unmap_vmas() returns. So the only responsibility here is to
853 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
854 * drops the lock and schedules.
855 */
856 unsigned long unmap_vmas(struct mmu_gather **tlbp,
857 struct vm_area_struct *vma, unsigned long start_addr,
858 unsigned long end_addr, unsigned long *nr_accounted,
859 struct zap_details *details)
860 {
861 long zap_work = ZAP_BLOCK_SIZE;
862 unsigned long tlb_start = 0; /* For tlb_finish_mmu */
863 int tlb_start_valid = 0;
864 unsigned long start = start_addr;
865 spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
866 int fullmm = (*tlbp)->fullmm;
867
868 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
869 unsigned long end;
870
871 start = max(vma->vm_start, start_addr);
872 if (start >= vma->vm_end)
873 continue;
874 end = min(vma->vm_end, end_addr);
875 if (end <= vma->vm_start)
876 continue;
877
878 if (vma->vm_flags & VM_ACCOUNT)
879 *nr_accounted += (end - start) >> PAGE_SHIFT;
880
881 while (start != end) {
882 if (!tlb_start_valid) {
883 tlb_start = start;
884 tlb_start_valid = 1;
885 }
886
887 if (unlikely(is_vm_hugetlb_page(vma))) {
888 unmap_hugepage_range(vma, start, end);
889 zap_work -= (end - start) /
890 (HPAGE_SIZE / PAGE_SIZE);
891 start = end;
892 } else
893 start = unmap_page_range(*tlbp, vma,
894 start, end, &zap_work, details);
895
896 if (zap_work > 0) {
897 BUG_ON(start != end);
898 break;
899 }
900
901 tlb_finish_mmu(*tlbp, tlb_start, start);
902
903 if (need_resched() ||
904 (i_mmap_lock && spin_needbreak(i_mmap_lock))) {
905 if (i_mmap_lock) {
906 *tlbp = NULL;
907 goto out;
908 }
909 cond_resched();
910 }
911
912 *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
913 tlb_start_valid = 0;
914 zap_work = ZAP_BLOCK_SIZE;
915 }
916 }
917 out:
918 return start; /* which is now the end (or restart) address */
919 }
920
921 /**
922 * zap_page_range - remove user pages in a given range
923 * @vma: vm_area_struct holding the applicable pages
924 * @address: starting address of pages to zap
925 * @size: number of bytes to zap
926 * @details: details of nonlinear truncation or shared cache invalidation
927 */
928 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
929 unsigned long size, struct zap_details *details)
930 {
931 struct mm_struct *mm = vma->vm_mm;
932 struct mmu_gather *tlb;
933 unsigned long end = address + size;
934 unsigned long nr_accounted = 0;
935
936 lru_add_drain();
937 tlb = tlb_gather_mmu(mm, 0);
938 update_hiwater_rss(mm);
939 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
940 if (tlb)
941 tlb_finish_mmu(tlb, address, end);
942 return end;
943 }
944
945 /*
946 * Do a quick page-table lookup for a single page.
947 */
948 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
949 unsigned int flags)
950 {
951 pgd_t *pgd;
952 pud_t *pud;
953 pmd_t *pmd;
954 pte_t *ptep, pte;
955 spinlock_t *ptl;
956 struct page *page;
957 struct mm_struct *mm = vma->vm_mm;
958
959 page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
960 if (!IS_ERR(page)) {
961 BUG_ON(flags & FOLL_GET);
962 goto out;
963 }
964
965 page = NULL;
966 pgd = pgd_offset(mm, address);
967 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
968 goto no_page_table;
969
970 pud = pud_offset(pgd, address);
971 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
972 goto no_page_table;
973
974 pmd = pmd_offset(pud, address);
975 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
976 goto no_page_table;
977
978 if (pmd_huge(*pmd)) {
979 BUG_ON(flags & FOLL_GET);
980 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
981 goto out;
982 }
983
984 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
985 if (!ptep)
986 goto out;
987
988 pte = *ptep;
989 if (!pte_present(pte))
990 goto unlock;
991 if ((flags & FOLL_WRITE) && !pte_write(pte))
992 goto unlock;
993 page = vm_normal_page(vma, address, pte);
994 if (unlikely(!page))
995 goto unlock;
996
997 if (flags & FOLL_GET)
998 get_page(page);
999 if (flags & FOLL_TOUCH) {
1000 if ((flags & FOLL_WRITE) &&
1001 !pte_dirty(pte) && !PageDirty(page))
1002 set_page_dirty(page);
1003 mark_page_accessed(page);
1004 }
1005 unlock:
1006 pte_unmap_unlock(ptep, ptl);
1007 out:
1008 return page;
1009
1010 no_page_table:
1011 /*
1012 * When core dumping an enormous anonymous area that nobody
1013 * has touched so far, we don't want to allocate page tables.
1014 */
1015 if (flags & FOLL_ANON) {
1016 page = ZERO_PAGE(0);
1017 if (flags & FOLL_GET)
1018 get_page(page);
1019 BUG_ON(flags & FOLL_WRITE);
1020 }
1021 return page;
1022 }
1023
1024 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1025 unsigned long start, int len, int write, int force,
1026 struct page **pages, struct vm_area_struct **vmas)
1027 {
1028 int i;
1029 unsigned int vm_flags;
1030
1031 if (len <= 0)
1032 return 0;
1033 /*
1034 * Require read or write permissions.
1035 * If 'force' is set, we only require the "MAY" flags.
1036 */
1037 vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1038 vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1039 i = 0;
1040
1041 do {
1042 struct vm_area_struct *vma;
1043 unsigned int foll_flags;
1044
1045 vma = find_extend_vma(mm, start);
1046 if (!vma && in_gate_area(tsk, start)) {
1047 unsigned long pg = start & PAGE_MASK;
1048 struct vm_area_struct *gate_vma = get_gate_vma(tsk);
1049 pgd_t *pgd;
1050 pud_t *pud;
1051 pmd_t *pmd;
1052 pte_t *pte;
1053 if (write) /* user gate pages are read-only */
1054 return i ? : -EFAULT;
1055 if (pg > TASK_SIZE)
1056 pgd = pgd_offset_k(pg);
1057 else
1058 pgd = pgd_offset_gate(mm, pg);
1059 BUG_ON(pgd_none(*pgd));
1060 pud = pud_offset(pgd, pg);
1061 BUG_ON(pud_none(*pud));
1062 pmd = pmd_offset(pud, pg);
1063 if (pmd_none(*pmd))
1064 return i ? : -EFAULT;
1065 pte = pte_offset_map(pmd, pg);
1066 if (pte_none(*pte)) {
1067 pte_unmap(pte);
1068 return i ? : -EFAULT;
1069 }
1070 if (pages) {
1071 struct page *page = vm_normal_page(gate_vma, start, *pte);
1072 pages[i] = page;
1073 if (page)
1074 get_page(page);
1075 }
1076 pte_unmap(pte);
1077 if (vmas)
1078 vmas[i] = gate_vma;
1079 i++;
1080 start += PAGE_SIZE;
1081 len--;
1082 continue;
1083 }
1084
1085 if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
1086 || !(vm_flags & vma->vm_flags))
1087 return i ? : -EFAULT;
1088
1089 if (is_vm_hugetlb_page(vma)) {
1090 i = follow_hugetlb_page(mm, vma, pages, vmas,
1091 &start, &len, i, write);
1092 continue;
1093 }
1094
1095 foll_flags = FOLL_TOUCH;
1096 if (pages)
1097 foll_flags |= FOLL_GET;
1098 if (!write && !(vma->vm_flags & VM_LOCKED) &&
1099 (!vma->vm_ops || (!vma->vm_ops->nopage &&
1100 !vma->vm_ops->fault)))
1101 foll_flags |= FOLL_ANON;
1102
1103 do {
1104 struct page *page;
1105
1106 /*
1107 * If tsk is ooming, cut off its access to large memory
1108 * allocations. It has a pending SIGKILL, but it can't
1109 * be processed until returning to user space.
1110 */
1111 if (unlikely(test_tsk_thread_flag(tsk, TIF_MEMDIE)))
1112 return -ENOMEM;
1113
1114 if (write)
1115 foll_flags |= FOLL_WRITE;
1116
1117 cond_resched();
1118 while (!(page = follow_page(vma, start, foll_flags))) {
1119 int ret;
1120 ret = handle_mm_fault(mm, vma, start,
1121 foll_flags & FOLL_WRITE);
1122 if (ret & VM_FAULT_ERROR) {
1123 if (ret & VM_FAULT_OOM)
1124 return i ? i : -ENOMEM;
1125 else if (ret & VM_FAULT_SIGBUS)
1126 return i ? i : -EFAULT;
1127 BUG();
1128 }
1129 if (ret & VM_FAULT_MAJOR)
1130 tsk->maj_flt++;
1131 else
1132 tsk->min_flt++;
1133
1134 /*
1135 * The VM_FAULT_WRITE bit tells us that
1136 * do_wp_page has broken COW when necessary,
1137 * even if maybe_mkwrite decided not to set
1138 * pte_write. We can thus safely do subsequent
1139 * page lookups as if they were reads.
1140 */
1141 if (ret & VM_FAULT_WRITE)
1142 foll_flags &= ~FOLL_WRITE;
1143
1144 cond_resched();
1145 }
1146 if (pages) {
1147 pages[i] = page;
1148
1149 flush_anon_page(vma, page, start);
1150 flush_dcache_page(page);
1151 }
1152 if (vmas)
1153 vmas[i] = vma;
1154 i++;
1155 start += PAGE_SIZE;
1156 len--;
1157 } while (len && start < vma->vm_end);
1158 } while (len);
1159 return i;
1160 }
1161 EXPORT_SYMBOL(get_user_pages);
1162
1163 pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
1164 spinlock_t **ptl)
1165 {
1166 pgd_t * pgd = pgd_offset(mm, addr);
1167 pud_t * pud = pud_alloc(mm, pgd, addr);
1168 if (pud) {
1169 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1170 if (pmd)
1171 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1172 }
1173 return NULL;
1174 }
1175
1176 /*
1177 * This is the old fallback for page remapping.
1178 *
1179 * For historical reasons, it only allows reserved pages. Only
1180 * old drivers should use this, and they needed to mark their
1181 * pages reserved for the old functions anyway.
1182 */
1183 static int insert_page(struct mm_struct *mm, unsigned long addr, struct page *page, pgprot_t prot)
1184 {
1185 int retval;
1186 pte_t *pte;
1187 spinlock_t *ptl;
1188
1189 retval = mem_cgroup_charge(page, mm, GFP_KERNEL);
1190 if (retval)
1191 goto out;
1192
1193 retval = -EINVAL;
1194 if (PageAnon(page))
1195 goto out_uncharge;
1196 retval = -ENOMEM;
1197 flush_dcache_page(page);
1198 pte = get_locked_pte(mm, addr, &ptl);
1199 if (!pte)
1200 goto out_uncharge;
1201 retval = -EBUSY;
1202 if (!pte_none(*pte))
1203 goto out_unlock;
1204
1205 /* Ok, finally just insert the thing.. */
1206 get_page(page);
1207 inc_mm_counter(mm, file_rss);
1208 page_add_file_rmap(page);
1209 set_pte_at(mm, addr, pte, mk_pte(page, prot));
1210
1211 retval = 0;
1212 pte_unmap_unlock(pte, ptl);
1213 return retval;
1214 out_unlock:
1215 pte_unmap_unlock(pte, ptl);
1216 out_uncharge:
1217 mem_cgroup_uncharge_page(page);
1218 out:
1219 return retval;
1220 }
1221
1222 /**
1223 * vm_insert_page - insert single page into user vma
1224 * @vma: user vma to map to
1225 * @addr: target user address of this page
1226 * @page: source kernel page
1227 *
1228 * This allows drivers to insert individual pages they've allocated
1229 * into a user vma.
1230 *
1231 * The page has to be a nice clean _individual_ kernel allocation.
1232 * If you allocate a compound page, you need to have marked it as
1233 * such (__GFP_COMP), or manually just split the page up yourself
1234 * (see split_page()).
1235 *
1236 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1237 * took an arbitrary page protection parameter. This doesn't allow
1238 * that. Your vma protection will have to be set up correctly, which
1239 * means that if you want a shared writable mapping, you'd better
1240 * ask for a shared writable mapping!
1241 *
1242 * The page does not need to be reserved.
1243 */
1244 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page *page)
1245 {
1246 if (addr < vma->vm_start || addr >= vma->vm_end)
1247 return -EFAULT;
1248 if (!page_count(page))
1249 return -EINVAL;
1250 vma->vm_flags |= VM_INSERTPAGE;
1251 return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
1252 }
1253 EXPORT_SYMBOL(vm_insert_page);
1254
1255 /**
1256 * vm_insert_pfn - insert single pfn into user vma
1257 * @vma: user vma to map to
1258 * @addr: target user address of this page
1259 * @pfn: source kernel pfn
1260 *
1261 * Similar to vm_inert_page, this allows drivers to insert individual pages
1262 * they've allocated into a user vma. Same comments apply.
1263 *
1264 * This function should only be called from a vm_ops->fault handler, and
1265 * in that case the handler should return NULL.
1266 */
1267 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1268 unsigned long pfn)
1269 {
1270 struct mm_struct *mm = vma->vm_mm;
1271 int retval;
1272 pte_t *pte, entry;
1273 spinlock_t *ptl;
1274
1275 BUG_ON(!(vma->vm_flags & VM_PFNMAP));
1276 BUG_ON(is_cow_mapping(vma->vm_flags));
1277
1278 retval = -ENOMEM;
1279 pte = get_locked_pte(mm, addr, &ptl);
1280 if (!pte)
1281 goto out;
1282 retval = -EBUSY;
1283 if (!pte_none(*pte))
1284 goto out_unlock;
1285
1286 /* Ok, finally just insert the thing.. */
1287 entry = pfn_pte(pfn, vma->vm_page_prot);
1288 set_pte_at(mm, addr, pte, entry);
1289 update_mmu_cache(vma, addr, entry);
1290
1291 retval = 0;
1292 out_unlock:
1293 pte_unmap_unlock(pte, ptl);
1294
1295 out:
1296 return retval;
1297 }
1298 EXPORT_SYMBOL(vm_insert_pfn);
1299
1300 /*
1301 * maps a range of physical memory into the requested pages. the old
1302 * mappings are removed. any references to nonexistent pages results
1303 * in null mappings (currently treated as "copy-on-access")
1304 */
1305 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1306 unsigned long addr, unsigned long end,
1307 unsigned long pfn, pgprot_t prot)
1308 {
1309 pte_t *pte;
1310 spinlock_t *ptl;
1311
1312 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1313 if (!pte)
1314 return -ENOMEM;
1315 arch_enter_lazy_mmu_mode();
1316 do {
1317 BUG_ON(!pte_none(*pte));
1318 set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
1319 pfn++;
1320 } while (pte++, addr += PAGE_SIZE, addr != end);
1321 arch_leave_lazy_mmu_mode();
1322 pte_unmap_unlock(pte - 1, ptl);
1323 return 0;
1324 }
1325
1326 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1327 unsigned long addr, unsigned long end,
1328 unsigned long pfn, pgprot_t prot)
1329 {
1330 pmd_t *pmd;
1331 unsigned long next;
1332
1333 pfn -= addr >> PAGE_SHIFT;
1334 pmd = pmd_alloc(mm, pud, addr);
1335 if (!pmd)
1336 return -ENOMEM;
1337 do {
1338 next = pmd_addr_end(addr, end);
1339 if (remap_pte_range(mm, pmd, addr, next,
1340 pfn + (addr >> PAGE_SHIFT), prot))
1341 return -ENOMEM;
1342 } while (pmd++, addr = next, addr != end);
1343 return 0;
1344 }
1345
1346 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1347 unsigned long addr, unsigned long end,
1348 unsigned long pfn, pgprot_t prot)
1349 {
1350 pud_t *pud;
1351 unsigned long next;
1352
1353 pfn -= addr >> PAGE_SHIFT;
1354 pud = pud_alloc(mm, pgd, addr);
1355 if (!pud)
1356 return -ENOMEM;
1357 do {
1358 next = pud_addr_end(addr, end);
1359 if (remap_pmd_range(mm, pud, addr, next,
1360 pfn + (addr >> PAGE_SHIFT), prot))
1361 return -ENOMEM;
1362 } while (pud++, addr = next, addr != end);
1363 return 0;
1364 }
1365
1366 /**
1367 * remap_pfn_range - remap kernel memory to userspace
1368 * @vma: user vma to map to
1369 * @addr: target user address to start at
1370 * @pfn: physical address of kernel memory
1371 * @size: size of map area
1372 * @prot: page protection flags for this mapping
1373 *
1374 * Note: this is only safe if the mm semaphore is held when called.
1375 */
1376 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1377 unsigned long pfn, unsigned long size, pgprot_t prot)
1378 {
1379 pgd_t *pgd;
1380 unsigned long next;
1381 unsigned long end = addr + PAGE_ALIGN(size);
1382 struct mm_struct *mm = vma->vm_mm;
1383 int err;
1384
1385 /*
1386 * Physically remapped pages are special. Tell the
1387 * rest of the world about it:
1388 * VM_IO tells people not to look at these pages
1389 * (accesses can have side effects).
1390 * VM_RESERVED is specified all over the place, because
1391 * in 2.4 it kept swapout's vma scan off this vma; but
1392 * in 2.6 the LRU scan won't even find its pages, so this
1393 * flag means no more than count its pages in reserved_vm,
1394 * and omit it from core dump, even when VM_IO turned off.
1395 * VM_PFNMAP tells the core MM that the base pages are just
1396 * raw PFN mappings, and do not have a "struct page" associated
1397 * with them.
1398 *
1399 * There's a horrible special case to handle copy-on-write
1400 * behaviour that some programs depend on. We mark the "original"
1401 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1402 */
1403 if (is_cow_mapping(vma->vm_flags)) {
1404 if (addr != vma->vm_start || end != vma->vm_end)
1405 return -EINVAL;
1406 vma->vm_pgoff = pfn;
1407 }
1408
1409 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1410
1411 BUG_ON(addr >= end);
1412 pfn -= addr >> PAGE_SHIFT;
1413 pgd = pgd_offset(mm, addr);
1414 flush_cache_range(vma, addr, end);
1415 do {
1416 next = pgd_addr_end(addr, end);
1417 err = remap_pud_range(mm, pgd, addr, next,
1418 pfn + (addr >> PAGE_SHIFT), prot);
1419 if (err)
1420 break;
1421 } while (pgd++, addr = next, addr != end);
1422 return err;
1423 }
1424 EXPORT_SYMBOL(remap_pfn_range);
1425
1426 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
1427 unsigned long addr, unsigned long end,
1428 pte_fn_t fn, void *data)
1429 {
1430 pte_t *pte;
1431 int err;
1432 pgtable_t token;
1433 spinlock_t *uninitialized_var(ptl);
1434
1435 pte = (mm == &init_mm) ?
1436 pte_alloc_kernel(pmd, addr) :
1437 pte_alloc_map_lock(mm, pmd, addr, &ptl);
1438 if (!pte)
1439 return -ENOMEM;
1440
1441 BUG_ON(pmd_huge(*pmd));
1442
1443 token = pmd_pgtable(*pmd);
1444
1445 do {
1446 err = fn(pte, token, addr, data);
1447 if (err)
1448 break;
1449 } while (pte++, addr += PAGE_SIZE, addr != end);
1450
1451 if (mm != &init_mm)
1452 pte_unmap_unlock(pte-1, ptl);
1453 return err;
1454 }
1455
1456 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
1457 unsigned long addr, unsigned long end,
1458 pte_fn_t fn, void *data)
1459 {
1460 pmd_t *pmd;
1461 unsigned long next;
1462 int err;
1463
1464 pmd = pmd_alloc(mm, pud, addr);
1465 if (!pmd)
1466 return -ENOMEM;
1467 do {
1468 next = pmd_addr_end(addr, end);
1469 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
1470 if (err)
1471 break;
1472 } while (pmd++, addr = next, addr != end);
1473 return err;
1474 }
1475
1476 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
1477 unsigned long addr, unsigned long end,
1478 pte_fn_t fn, void *data)
1479 {
1480 pud_t *pud;
1481 unsigned long next;
1482 int err;
1483
1484 pud = pud_alloc(mm, pgd, addr);
1485 if (!pud)
1486 return -ENOMEM;
1487 do {
1488 next = pud_addr_end(addr, end);
1489 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
1490 if (err)
1491 break;
1492 } while (pud++, addr = next, addr != end);
1493 return err;
1494 }
1495
1496 /*
1497 * Scan a region of virtual memory, filling in page tables as necessary
1498 * and calling a provided function on each leaf page table.
1499 */
1500 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
1501 unsigned long size, pte_fn_t fn, void *data)
1502 {
1503 pgd_t *pgd;
1504 unsigned long next;
1505 unsigned long end = addr + size;
1506 int err;
1507
1508 BUG_ON(addr >= end);
1509 pgd = pgd_offset(mm, addr);
1510 do {
1511 next = pgd_addr_end(addr, end);
1512 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
1513 if (err)
1514 break;
1515 } while (pgd++, addr = next, addr != end);
1516 return err;
1517 }
1518 EXPORT_SYMBOL_GPL(apply_to_page_range);
1519
1520 /*
1521 * handle_pte_fault chooses page fault handler according to an entry
1522 * which was read non-atomically. Before making any commitment, on
1523 * those architectures or configurations (e.g. i386 with PAE) which
1524 * might give a mix of unmatched parts, do_swap_page and do_file_page
1525 * must check under lock before unmapping the pte and proceeding
1526 * (but do_wp_page is only called after already making such a check;
1527 * and do_anonymous_page and do_no_page can safely check later on).
1528 */
1529 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1530 pte_t *page_table, pte_t orig_pte)
1531 {
1532 int same = 1;
1533 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1534 if (sizeof(pte_t) > sizeof(unsigned long)) {
1535 spinlock_t *ptl = pte_lockptr(mm, pmd);
1536 spin_lock(ptl);
1537 same = pte_same(*page_table, orig_pte);
1538 spin_unlock(ptl);
1539 }
1540 #endif
1541 pte_unmap(page_table);
1542 return same;
1543 }
1544
1545 /*
1546 * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when
1547 * servicing faults for write access. In the normal case, do always want
1548 * pte_mkwrite. But get_user_pages can cause write faults for mappings
1549 * that do not have writing enabled, when used by access_process_vm.
1550 */
1551 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
1552 {
1553 if (likely(vma->vm_flags & VM_WRITE))
1554 pte = pte_mkwrite(pte);
1555 return pte;
1556 }
1557
1558 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1559 {
1560 /*
1561 * If the source page was a PFN mapping, we don't have
1562 * a "struct page" for it. We do a best-effort copy by
1563 * just copying from the original user address. If that
1564 * fails, we just zero-fill it. Live with it.
1565 */
1566 if (unlikely(!src)) {
1567 void *kaddr = kmap_atomic(dst, KM_USER0);
1568 void __user *uaddr = (void __user *)(va & PAGE_MASK);
1569
1570 /*
1571 * This really shouldn't fail, because the page is there
1572 * in the page tables. But it might just be unreadable,
1573 * in which case we just give up and fill the result with
1574 * zeroes.
1575 */
1576 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1577 memset(kaddr, 0, PAGE_SIZE);
1578 kunmap_atomic(kaddr, KM_USER0);
1579 flush_dcache_page(dst);
1580 } else
1581 copy_user_highpage(dst, src, va, vma);
1582 }
1583
1584 /*
1585 * This routine handles present pages, when users try to write
1586 * to a shared page. It is done by copying the page to a new address
1587 * and decrementing the shared-page counter for the old page.
1588 *
1589 * Note that this routine assumes that the protection checks have been
1590 * done by the caller (the low-level page fault routine in most cases).
1591 * Thus we can safely just mark it writable once we've done any necessary
1592 * COW.
1593 *
1594 * We also mark the page dirty at this point even though the page will
1595 * change only once the write actually happens. This avoids a few races,
1596 * and potentially makes it more efficient.
1597 *
1598 * We enter with non-exclusive mmap_sem (to exclude vma changes,
1599 * but allow concurrent faults), with pte both mapped and locked.
1600 * We return with mmap_sem still held, but pte unmapped and unlocked.
1601 */
1602 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1603 unsigned long address, pte_t *page_table, pmd_t *pmd,
1604 spinlock_t *ptl, pte_t orig_pte)
1605 {
1606 struct page *old_page, *new_page;
1607 pte_t entry;
1608 int reuse = 0, ret = 0;
1609 int page_mkwrite = 0;
1610 struct page *dirty_page = NULL;
1611
1612 old_page = vm_normal_page(vma, address, orig_pte);
1613 if (!old_page)
1614 goto gotten;
1615
1616 /*
1617 * Take out anonymous pages first, anonymous shared vmas are
1618 * not dirty accountable.
1619 */
1620 if (PageAnon(old_page)) {
1621 if (!TestSetPageLocked(old_page)) {
1622 reuse = can_share_swap_page(old_page);
1623 unlock_page(old_page);
1624 }
1625 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1626 (VM_WRITE|VM_SHARED))) {
1627 /*
1628 * Only catch write-faults on shared writable pages,
1629 * read-only shared pages can get COWed by
1630 * get_user_pages(.write=1, .force=1).
1631 */
1632 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
1633 /*
1634 * Notify the address space that the page is about to
1635 * become writable so that it can prohibit this or wait
1636 * for the page to get into an appropriate state.
1637 *
1638 * We do this without the lock held, so that it can
1639 * sleep if it needs to.
1640 */
1641 page_cache_get(old_page);
1642 pte_unmap_unlock(page_table, ptl);
1643
1644 if (vma->vm_ops->page_mkwrite(vma, old_page) < 0)
1645 goto unwritable_page;
1646
1647 /*
1648 * Since we dropped the lock we need to revalidate
1649 * the PTE as someone else may have changed it. If
1650 * they did, we just return, as we can count on the
1651 * MMU to tell us if they didn't also make it writable.
1652 */
1653 page_table = pte_offset_map_lock(mm, pmd, address,
1654 &ptl);
1655 page_cache_release(old_page);
1656 if (!pte_same(*page_table, orig_pte))
1657 goto unlock;
1658
1659 page_mkwrite = 1;
1660 }
1661 dirty_page = old_page;
1662 get_page(dirty_page);
1663 reuse = 1;
1664 }
1665
1666 if (reuse) {
1667 flush_cache_page(vma, address, pte_pfn(orig_pte));
1668 entry = pte_mkyoung(orig_pte);
1669 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1670 if (ptep_set_access_flags(vma, address, page_table, entry,1))
1671 update_mmu_cache(vma, address, entry);
1672 ret |= VM_FAULT_WRITE;
1673 goto unlock;
1674 }
1675
1676 /*
1677 * Ok, we need to copy. Oh, well..
1678 */
1679 page_cache_get(old_page);
1680 gotten:
1681 pte_unmap_unlock(page_table, ptl);
1682
1683 if (unlikely(anon_vma_prepare(vma)))
1684 goto oom;
1685 VM_BUG_ON(old_page == ZERO_PAGE(0));
1686 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
1687 if (!new_page)
1688 goto oom;
1689 cow_user_page(new_page, old_page, address, vma);
1690 __SetPageUptodate(new_page);
1691
1692 if (mem_cgroup_charge(new_page, mm, GFP_KERNEL))
1693 goto oom_free_new;
1694
1695 /*
1696 * Re-check the pte - we dropped the lock
1697 */
1698 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1699 if (likely(pte_same(*page_table, orig_pte))) {
1700 if (old_page) {
1701 page_remove_rmap(old_page, vma);
1702 if (!PageAnon(old_page)) {
1703 dec_mm_counter(mm, file_rss);
1704 inc_mm_counter(mm, anon_rss);
1705 }
1706 } else
1707 inc_mm_counter(mm, anon_rss);
1708 flush_cache_page(vma, address, pte_pfn(orig_pte));
1709 entry = mk_pte(new_page, vma->vm_page_prot);
1710 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1711 /*
1712 * Clear the pte entry and flush it first, before updating the
1713 * pte with the new entry. This will avoid a race condition
1714 * seen in the presence of one thread doing SMC and another
1715 * thread doing COW.
1716 */
1717 ptep_clear_flush(vma, address, page_table);
1718 set_pte_at(mm, address, page_table, entry);
1719 update_mmu_cache(vma, address, entry);
1720 lru_cache_add_active(new_page);
1721 page_add_new_anon_rmap(new_page, vma, address);
1722
1723 /* Free the old page.. */
1724 new_page = old_page;
1725 ret |= VM_FAULT_WRITE;
1726 } else
1727 mem_cgroup_uncharge_page(new_page);
1728
1729 if (new_page)
1730 page_cache_release(new_page);
1731 if (old_page)
1732 page_cache_release(old_page);
1733 unlock:
1734 pte_unmap_unlock(page_table, ptl);
1735 if (dirty_page) {
1736 if (vma->vm_file)
1737 file_update_time(vma->vm_file);
1738
1739 /*
1740 * Yes, Virginia, this is actually required to prevent a race
1741 * with clear_page_dirty_for_io() from clearing the page dirty
1742 * bit after it clear all dirty ptes, but before a racing
1743 * do_wp_page installs a dirty pte.
1744 *
1745 * do_no_page is protected similarly.
1746 */
1747 wait_on_page_locked(dirty_page);
1748 set_page_dirty_balance(dirty_page, page_mkwrite);
1749 put_page(dirty_page);
1750 }
1751 return ret;
1752 oom_free_new:
1753 page_cache_release(new_page);
1754 oom:
1755 if (old_page)
1756 page_cache_release(old_page);
1757 return VM_FAULT_OOM;
1758
1759 unwritable_page:
1760 page_cache_release(old_page);
1761 return VM_FAULT_SIGBUS;
1762 }
1763
1764 /*
1765 * Helper functions for unmap_mapping_range().
1766 *
1767 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
1768 *
1769 * We have to restart searching the prio_tree whenever we drop the lock,
1770 * since the iterator is only valid while the lock is held, and anyway
1771 * a later vma might be split and reinserted earlier while lock dropped.
1772 *
1773 * The list of nonlinear vmas could be handled more efficiently, using
1774 * a placeholder, but handle it in the same way until a need is shown.
1775 * It is important to search the prio_tree before nonlinear list: a vma
1776 * may become nonlinear and be shifted from prio_tree to nonlinear list
1777 * while the lock is dropped; but never shifted from list to prio_tree.
1778 *
1779 * In order to make forward progress despite restarting the search,
1780 * vm_truncate_count is used to mark a vma as now dealt with, so we can
1781 * quickly skip it next time around. Since the prio_tree search only
1782 * shows us those vmas affected by unmapping the range in question, we
1783 * can't efficiently keep all vmas in step with mapping->truncate_count:
1784 * so instead reset them all whenever it wraps back to 0 (then go to 1).
1785 * mapping->truncate_count and vma->vm_truncate_count are protected by
1786 * i_mmap_lock.
1787 *
1788 * In order to make forward progress despite repeatedly restarting some
1789 * large vma, note the restart_addr from unmap_vmas when it breaks out:
1790 * and restart from that address when we reach that vma again. It might
1791 * have been split or merged, shrunk or extended, but never shifted: so
1792 * restart_addr remains valid so long as it remains in the vma's range.
1793 * unmap_mapping_range forces truncate_count to leap over page-aligned
1794 * values so we can save vma's restart_addr in its truncate_count field.
1795 */
1796 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
1797
1798 static void reset_vma_truncate_counts(struct address_space *mapping)
1799 {
1800 struct vm_area_struct *vma;
1801 struct prio_tree_iter iter;
1802
1803 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
1804 vma->vm_truncate_count = 0;
1805 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
1806 vma->vm_truncate_count = 0;
1807 }
1808
1809 static int unmap_mapping_range_vma(struct vm_area_struct *vma,
1810 unsigned long start_addr, unsigned long end_addr,
1811 struct zap_details *details)
1812 {
1813 unsigned long restart_addr;
1814 int need_break;
1815
1816 /*
1817 * files that support invalidating or truncating portions of the
1818 * file from under mmaped areas must have their ->fault function
1819 * return a locked page (and set VM_FAULT_LOCKED in the return).
1820 * This provides synchronisation against concurrent unmapping here.
1821 */
1822
1823 again:
1824 restart_addr = vma->vm_truncate_count;
1825 if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
1826 start_addr = restart_addr;
1827 if (start_addr >= end_addr) {
1828 /* Top of vma has been split off since last time */
1829 vma->vm_truncate_count = details->truncate_count;
1830 return 0;
1831 }
1832 }
1833
1834 restart_addr = zap_page_range(vma, start_addr,
1835 end_addr - start_addr, details);
1836 need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
1837
1838 if (restart_addr >= end_addr) {
1839 /* We have now completed this vma: mark it so */
1840 vma->vm_truncate_count = details->truncate_count;
1841 if (!need_break)
1842 return 0;
1843 } else {
1844 /* Note restart_addr in vma's truncate_count field */
1845 vma->vm_truncate_count = restart_addr;
1846 if (!need_break)
1847 goto again;
1848 }
1849
1850 spin_unlock(details->i_mmap_lock);
1851 cond_resched();
1852 spin_lock(details->i_mmap_lock);
1853 return -EINTR;
1854 }
1855
1856 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
1857 struct zap_details *details)
1858 {
1859 struct vm_area_struct *vma;
1860 struct prio_tree_iter iter;
1861 pgoff_t vba, vea, zba, zea;
1862
1863 restart:
1864 vma_prio_tree_foreach(vma, &iter, root,
1865 details->first_index, details->last_index) {
1866 /* Skip quickly over those we have already dealt with */
1867 if (vma->vm_truncate_count == details->truncate_count)
1868 continue;
1869
1870 vba = vma->vm_pgoff;
1871 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
1872 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
1873 zba = details->first_index;
1874 if (zba < vba)
1875 zba = vba;
1876 zea = details->last_index;
1877 if (zea > vea)
1878 zea = vea;
1879
1880 if (unmap_mapping_range_vma(vma,
1881 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
1882 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
1883 details) < 0)
1884 goto restart;
1885 }
1886 }
1887
1888 static inline void unmap_mapping_range_list(struct list_head *head,
1889 struct zap_details *details)
1890 {
1891 struct vm_area_struct *vma;
1892
1893 /*
1894 * In nonlinear VMAs there is no correspondence between virtual address
1895 * offset and file offset. So we must perform an exhaustive search
1896 * across *all* the pages in each nonlinear VMA, not just the pages
1897 * whose virtual address lies outside the file truncation point.
1898 */
1899 restart:
1900 list_for_each_entry(vma, head, shared.vm_set.list) {
1901 /* Skip quickly over those we have already dealt with */
1902 if (vma->vm_truncate_count == details->truncate_count)
1903 continue;
1904 details->nonlinear_vma = vma;
1905 if (unmap_mapping_range_vma(vma, vma->vm_start,
1906 vma->vm_end, details) < 0)
1907 goto restart;
1908 }
1909 }
1910
1911 /**
1912 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
1913 * @mapping: the address space containing mmaps to be unmapped.
1914 * @holebegin: byte in first page to unmap, relative to the start of
1915 * the underlying file. This will be rounded down to a PAGE_SIZE
1916 * boundary. Note that this is different from vmtruncate(), which
1917 * must keep the partial page. In contrast, we must get rid of
1918 * partial pages.
1919 * @holelen: size of prospective hole in bytes. This will be rounded
1920 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
1921 * end of the file.
1922 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
1923 * but 0 when invalidating pagecache, don't throw away private data.
1924 */
1925 void unmap_mapping_range(struct address_space *mapping,
1926 loff_t const holebegin, loff_t const holelen, int even_cows)
1927 {
1928 struct zap_details details;
1929 pgoff_t hba = holebegin >> PAGE_SHIFT;
1930 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1931
1932 /* Check for overflow. */
1933 if (sizeof(holelen) > sizeof(hlen)) {
1934 long long holeend =
1935 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1936 if (holeend & ~(long long)ULONG_MAX)
1937 hlen = ULONG_MAX - hba + 1;
1938 }
1939
1940 details.check_mapping = even_cows? NULL: mapping;
1941 details.nonlinear_vma = NULL;
1942 details.first_index = hba;
1943 details.last_index = hba + hlen - 1;
1944 if (details.last_index < details.first_index)
1945 details.last_index = ULONG_MAX;
1946 details.i_mmap_lock = &mapping->i_mmap_lock;
1947
1948 spin_lock(&mapping->i_mmap_lock);
1949
1950 /* Protect against endless unmapping loops */
1951 mapping->truncate_count++;
1952 if (unlikely(is_restart_addr(mapping->truncate_count))) {
1953 if (mapping->truncate_count == 0)
1954 reset_vma_truncate_counts(mapping);
1955 mapping->truncate_count++;
1956 }
1957 details.truncate_count = mapping->truncate_count;
1958
1959 if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
1960 unmap_mapping_range_tree(&mapping->i_mmap, &details);
1961 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
1962 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
1963 spin_unlock(&mapping->i_mmap_lock);
1964 }
1965 EXPORT_SYMBOL(unmap_mapping_range);
1966
1967 /**
1968 * vmtruncate - unmap mappings "freed" by truncate() syscall
1969 * @inode: inode of the file used
1970 * @offset: file offset to start truncating
1971 *
1972 * NOTE! We have to be ready to update the memory sharing
1973 * between the file and the memory map for a potential last
1974 * incomplete page. Ugly, but necessary.
1975 */
1976 int vmtruncate(struct inode * inode, loff_t offset)
1977 {
1978 if (inode->i_size < offset) {
1979 unsigned long limit;
1980
1981 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1982 if (limit != RLIM_INFINITY && offset > limit)
1983 goto out_sig;
1984 if (offset > inode->i_sb->s_maxbytes)
1985 goto out_big;
1986 i_size_write(inode, offset);
1987 } else {
1988 struct address_space *mapping = inode->i_mapping;
1989
1990 /*
1991 * truncation of in-use swapfiles is disallowed - it would
1992 * cause subsequent swapout to scribble on the now-freed
1993 * blocks.
1994 */
1995 if (IS_SWAPFILE(inode))
1996 return -ETXTBSY;
1997 i_size_write(inode, offset);
1998
1999 /*
2000 * unmap_mapping_range is called twice, first simply for
2001 * efficiency so that truncate_inode_pages does fewer
2002 * single-page unmaps. However after this first call, and
2003 * before truncate_inode_pages finishes, it is possible for
2004 * private pages to be COWed, which remain after
2005 * truncate_inode_pages finishes, hence the second
2006 * unmap_mapping_range call must be made for correctness.
2007 */
2008 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
2009 truncate_inode_pages(mapping, offset);
2010 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
2011 }
2012
2013 if (inode->i_op && inode->i_op->truncate)
2014 inode->i_op->truncate(inode);
2015 return 0;
2016
2017 out_sig:
2018 send_sig(SIGXFSZ, current, 0);
2019 out_big:
2020 return -EFBIG;
2021 }
2022 EXPORT_SYMBOL(vmtruncate);
2023
2024 int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
2025 {
2026 struct address_space *mapping = inode->i_mapping;
2027
2028 /*
2029 * If the underlying filesystem is not going to provide
2030 * a way to truncate a range of blocks (punch a hole) -
2031 * we should return failure right now.
2032 */
2033 if (!inode->i_op || !inode->i_op->truncate_range)
2034 return -ENOSYS;
2035
2036 mutex_lock(&inode->i_mutex);
2037 down_write(&inode->i_alloc_sem);
2038 unmap_mapping_range(mapping, offset, (end - offset), 1);
2039 truncate_inode_pages_range(mapping, offset, end);
2040 unmap_mapping_range(mapping, offset, (end - offset), 1);
2041 inode->i_op->truncate_range(inode, offset, end);
2042 up_write(&inode->i_alloc_sem);
2043 mutex_unlock(&inode->i_mutex);
2044
2045 return 0;
2046 }
2047
2048 /*
2049 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2050 * but allow concurrent faults), and pte mapped but not yet locked.
2051 * We return with mmap_sem still held, but pte unmapped and unlocked.
2052 */
2053 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2054 unsigned long address, pte_t *page_table, pmd_t *pmd,
2055 int write_access, pte_t orig_pte)
2056 {
2057 spinlock_t *ptl;
2058 struct page *page;
2059 swp_entry_t entry;
2060 pte_t pte;
2061 int ret = 0;
2062
2063 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2064 goto out;
2065
2066 entry = pte_to_swp_entry(orig_pte);
2067 if (is_migration_entry(entry)) {
2068 migration_entry_wait(mm, pmd, address);
2069 goto out;
2070 }
2071 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2072 page = lookup_swap_cache(entry);
2073 if (!page) {
2074 grab_swap_token(); /* Contend for token _before_ read-in */
2075 page = swapin_readahead(entry,
2076 GFP_HIGHUSER_MOVABLE, vma, address);
2077 if (!page) {
2078 /*
2079 * Back out if somebody else faulted in this pte
2080 * while we released the pte lock.
2081 */
2082 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2083 if (likely(pte_same(*page_table, orig_pte)))
2084 ret = VM_FAULT_OOM;
2085 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2086 goto unlock;
2087 }
2088
2089 /* Had to read the page from swap area: Major fault */
2090 ret = VM_FAULT_MAJOR;
2091 count_vm_event(PGMAJFAULT);
2092 }
2093
2094 if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
2095 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2096 ret = VM_FAULT_OOM;
2097 goto out;
2098 }
2099
2100 mark_page_accessed(page);
2101 lock_page(page);
2102 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2103
2104 /*
2105 * Back out if somebody else already faulted in this pte.
2106 */
2107 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2108 if (unlikely(!pte_same(*page_table, orig_pte)))
2109 goto out_nomap;
2110
2111 if (unlikely(!PageUptodate(page))) {
2112 ret = VM_FAULT_SIGBUS;
2113 goto out_nomap;
2114 }
2115
2116 /* The page isn't present yet, go ahead with the fault. */
2117
2118 inc_mm_counter(mm, anon_rss);
2119 pte = mk_pte(page, vma->vm_page_prot);
2120 if (write_access && can_share_swap_page(page)) {
2121 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2122 write_access = 0;
2123 }
2124
2125 flush_icache_page(vma, page);
2126 set_pte_at(mm, address, page_table, pte);
2127 page_add_anon_rmap(page, vma, address);
2128
2129 swap_free(entry);
2130 if (vm_swap_full())
2131 remove_exclusive_swap_page(page);
2132 unlock_page(page);
2133
2134 if (write_access) {
2135 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
2136 if (ret & VM_FAULT_ERROR)
2137 ret &= VM_FAULT_ERROR;
2138 goto out;
2139 }
2140
2141 /* No need to invalidate - it was non-present before */
2142 update_mmu_cache(vma, address, pte);
2143 unlock:
2144 pte_unmap_unlock(page_table, ptl);
2145 out:
2146 return ret;
2147 out_nomap:
2148 mem_cgroup_uncharge_page(page);
2149 pte_unmap_unlock(page_table, ptl);
2150 unlock_page(page);
2151 page_cache_release(page);
2152 return ret;
2153 }
2154
2155 /*
2156 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2157 * but allow concurrent faults), and pte mapped but not yet locked.
2158 * We return with mmap_sem still held, but pte unmapped and unlocked.
2159 */
2160 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
2161 unsigned long address, pte_t *page_table, pmd_t *pmd,
2162 int write_access)
2163 {
2164 struct page *page;
2165 spinlock_t *ptl;
2166 pte_t entry;
2167
2168 /* Allocate our own private page. */
2169 pte_unmap(page_table);
2170
2171 if (unlikely(anon_vma_prepare(vma)))
2172 goto oom;
2173 page = alloc_zeroed_user_highpage_movable(vma, address);
2174 if (!page)
2175 goto oom;
2176 __SetPageUptodate(page);
2177
2178 if (mem_cgroup_charge(page, mm, GFP_KERNEL))
2179 goto oom_free_page;
2180
2181 entry = mk_pte(page, vma->vm_page_prot);
2182 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2183
2184 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2185 if (!pte_none(*page_table))
2186 goto release;
2187 inc_mm_counter(mm, anon_rss);
2188 lru_cache_add_active(page);
2189 page_add_new_anon_rmap(page, vma, address);
2190 set_pte_at(mm, address, page_table, entry);
2191
2192 /* No need to invalidate - it was non-present before */
2193 update_mmu_cache(vma, address, entry);
2194 unlock:
2195 pte_unmap_unlock(page_table, ptl);
2196 return 0;
2197 release:
2198 mem_cgroup_uncharge_page(page);
2199 page_cache_release(page);
2200 goto unlock;
2201 oom_free_page:
2202 page_cache_release(page);
2203 oom:
2204 return VM_FAULT_OOM;
2205 }
2206
2207 /*
2208 * __do_fault() tries to create a new page mapping. It aggressively
2209 * tries to share with existing pages, but makes a separate copy if
2210 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
2211 * the next page fault.
2212 *
2213 * As this is called only for pages that do not currently exist, we
2214 * do not need to flush old virtual caches or the TLB.
2215 *
2216 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2217 * but allow concurrent faults), and pte neither mapped nor locked.
2218 * We return with mmap_sem still held, but pte unmapped and unlocked.
2219 */
2220 static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2221 unsigned long address, pmd_t *pmd,
2222 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
2223 {
2224 pte_t *page_table;
2225 spinlock_t *ptl;
2226 struct page *page;
2227 pte_t entry;
2228 int anon = 0;
2229 struct page *dirty_page = NULL;
2230 struct vm_fault vmf;
2231 int ret;
2232 int page_mkwrite = 0;
2233
2234 vmf.virtual_address = (void __user *)(address & PAGE_MASK);
2235 vmf.pgoff = pgoff;
2236 vmf.flags = flags;
2237 vmf.page = NULL;
2238
2239 BUG_ON(vma->vm_flags & VM_PFNMAP);
2240
2241 if (likely(vma->vm_ops->fault)) {
2242 ret = vma->vm_ops->fault(vma, &vmf);
2243 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2244 return ret;
2245 } else {
2246 /* Legacy ->nopage path */
2247 ret = 0;
2248 vmf.page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
2249 /* no page was available -- either SIGBUS or OOM */
2250 if (unlikely(vmf.page == NOPAGE_SIGBUS))
2251 return VM_FAULT_SIGBUS;
2252 else if (unlikely(vmf.page == NOPAGE_OOM))
2253 return VM_FAULT_OOM;
2254 }
2255
2256 /*
2257 * For consistency in subsequent calls, make the faulted page always
2258 * locked.
2259 */
2260 if (unlikely(!(ret & VM_FAULT_LOCKED)))
2261 lock_page(vmf.page);
2262 else
2263 VM_BUG_ON(!PageLocked(vmf.page));
2264
2265 /*
2266 * Should we do an early C-O-W break?
2267 */
2268 page = vmf.page;
2269 if (flags & FAULT_FLAG_WRITE) {
2270 if (!(vma->vm_flags & VM_SHARED)) {
2271 anon = 1;
2272 if (unlikely(anon_vma_prepare(vma))) {
2273 ret = VM_FAULT_OOM;
2274 goto out;
2275 }
2276 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
2277 vma, address);
2278 if (!page) {
2279 ret = VM_FAULT_OOM;
2280 goto out;
2281 }
2282 copy_user_highpage(page, vmf.page, address, vma);
2283 __SetPageUptodate(page);
2284 } else {
2285 /*
2286 * If the page will be shareable, see if the backing
2287 * address space wants to know that the page is about
2288 * to become writable
2289 */
2290 if (vma->vm_ops->page_mkwrite) {
2291 unlock_page(page);
2292 if (vma->vm_ops->page_mkwrite(vma, page) < 0) {
2293 ret = VM_FAULT_SIGBUS;
2294 anon = 1; /* no anon but release vmf.page */
2295 goto out_unlocked;
2296 }
2297 lock_page(page);
2298 /*
2299 * XXX: this is not quite right (racy vs
2300 * invalidate) to unlock and relock the page
2301 * like this, however a better fix requires
2302 * reworking page_mkwrite locking API, which
2303 * is better done later.
2304 */
2305 if (!page->mapping) {
2306 ret = 0;
2307 anon = 1; /* no anon but release vmf.page */
2308 goto out;
2309 }
2310 page_mkwrite = 1;
2311 }
2312 }
2313
2314 }
2315
2316 if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
2317 ret = VM_FAULT_OOM;
2318 goto out;
2319 }
2320
2321 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2322
2323 /*
2324 * This silly early PAGE_DIRTY setting removes a race
2325 * due to the bad i386 page protection. But it's valid
2326 * for other architectures too.
2327 *
2328 * Note that if write_access is true, we either now have
2329 * an exclusive copy of the page, or this is a shared mapping,
2330 * so we can make it writable and dirty to avoid having to
2331 * handle that later.
2332 */
2333 /* Only go through if we didn't race with anybody else... */
2334 if (likely(pte_same(*page_table, orig_pte))) {
2335 flush_icache_page(vma, page);
2336 entry = mk_pte(page, vma->vm_page_prot);
2337 if (flags & FAULT_FLAG_WRITE)
2338 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2339 set_pte_at(mm, address, page_table, entry);
2340 if (anon) {
2341 inc_mm_counter(mm, anon_rss);
2342 lru_cache_add_active(page);
2343 page_add_new_anon_rmap(page, vma, address);
2344 } else {
2345 inc_mm_counter(mm, file_rss);
2346 page_add_file_rmap(page);
2347 if (flags & FAULT_FLAG_WRITE) {
2348 dirty_page = page;
2349 get_page(dirty_page);
2350 }
2351 }
2352
2353 /* no need to invalidate: a not-present page won't be cached */
2354 update_mmu_cache(vma, address, entry);
2355 } else {
2356 mem_cgroup_uncharge_page(page);
2357 if (anon)
2358 page_cache_release(page);
2359 else
2360 anon = 1; /* no anon but release faulted_page */
2361 }
2362
2363 pte_unmap_unlock(page_table, ptl);
2364
2365 out:
2366 unlock_page(vmf.page);
2367 out_unlocked:
2368 if (anon)
2369 page_cache_release(vmf.page);
2370 else if (dirty_page) {
2371 if (vma->vm_file)
2372 file_update_time(vma->vm_file);
2373
2374 set_page_dirty_balance(dirty_page, page_mkwrite);
2375 put_page(dirty_page);
2376 }
2377
2378 return ret;
2379 }
2380
2381 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2382 unsigned long address, pte_t *page_table, pmd_t *pmd,
2383 int write_access, pte_t orig_pte)
2384 {
2385 pgoff_t pgoff = (((address & PAGE_MASK)
2386 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2387 unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0);
2388
2389 pte_unmap(page_table);
2390 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2391 }
2392
2393
2394 /*
2395 * do_no_pfn() tries to create a new page mapping for a page without
2396 * a struct_page backing it
2397 *
2398 * As this is called only for pages that do not currently exist, we
2399 * do not need to flush old virtual caches or the TLB.
2400 *
2401 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2402 * but allow concurrent faults), and pte mapped but not yet locked.
2403 * We return with mmap_sem still held, but pte unmapped and unlocked.
2404 *
2405 * It is expected that the ->nopfn handler always returns the same pfn
2406 * for a given virtual mapping.
2407 *
2408 * Mark this `noinline' to prevent it from bloating the main pagefault code.
2409 */
2410 static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma,
2411 unsigned long address, pte_t *page_table, pmd_t *pmd,
2412 int write_access)
2413 {
2414 spinlock_t *ptl;
2415 pte_t entry;
2416 unsigned long pfn;
2417
2418 pte_unmap(page_table);
2419 BUG_ON(!(vma->vm_flags & VM_PFNMAP));
2420 BUG_ON(is_cow_mapping(vma->vm_flags));
2421
2422 pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK);
2423 if (unlikely(pfn == NOPFN_OOM))
2424 return VM_FAULT_OOM;
2425 else if (unlikely(pfn == NOPFN_SIGBUS))
2426 return VM_FAULT_SIGBUS;
2427 else if (unlikely(pfn == NOPFN_REFAULT))
2428 return 0;
2429
2430 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2431
2432 /* Only go through if we didn't race with anybody else... */
2433 if (pte_none(*page_table)) {
2434 entry = pfn_pte(pfn, vma->vm_page_prot);
2435 if (write_access)
2436 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2437 set_pte_at(mm, address, page_table, entry);
2438 }
2439 pte_unmap_unlock(page_table, ptl);
2440 return 0;
2441 }
2442
2443 /*
2444 * Fault of a previously existing named mapping. Repopulate the pte
2445 * from the encoded file_pte if possible. This enables swappable
2446 * nonlinear vmas.
2447 *
2448 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2449 * but allow concurrent faults), and pte mapped but not yet locked.
2450 * We return with mmap_sem still held, but pte unmapped and unlocked.
2451 */
2452 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2453 unsigned long address, pte_t *page_table, pmd_t *pmd,
2454 int write_access, pte_t orig_pte)
2455 {
2456 unsigned int flags = FAULT_FLAG_NONLINEAR |
2457 (write_access ? FAULT_FLAG_WRITE : 0);
2458 pgoff_t pgoff;
2459
2460 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2461 return 0;
2462
2463 if (unlikely(!(vma->vm_flags & VM_NONLINEAR) ||
2464 !(vma->vm_flags & VM_CAN_NONLINEAR))) {
2465 /*
2466 * Page table corrupted: show pte and kill process.
2467 */
2468 print_bad_pte(vma, orig_pte, address);
2469 return VM_FAULT_OOM;
2470 }
2471
2472 pgoff = pte_to_pgoff(orig_pte);
2473 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2474 }
2475
2476 /*
2477 * These routines also need to handle stuff like marking pages dirty
2478 * and/or accessed for architectures that don't do it in hardware (most
2479 * RISC architectures). The early dirtying is also good on the i386.
2480 *
2481 * There is also a hook called "update_mmu_cache()" that architectures
2482 * with external mmu caches can use to update those (ie the Sparc or
2483 * PowerPC hashed page tables that act as extended TLBs).
2484 *
2485 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2486 * but allow concurrent faults), and pte mapped but not yet locked.
2487 * We return with mmap_sem still held, but pte unmapped and unlocked.
2488 */
2489 static inline int handle_pte_fault(struct mm_struct *mm,
2490 struct vm_area_struct *vma, unsigned long address,
2491 pte_t *pte, pmd_t *pmd, int write_access)
2492 {
2493 pte_t entry;
2494 spinlock_t *ptl;
2495
2496 entry = *pte;
2497 if (!pte_present(entry)) {
2498 if (pte_none(entry)) {
2499 if (vma->vm_ops) {
2500 if (vma->vm_ops->fault || vma->vm_ops->nopage)
2501 return do_linear_fault(mm, vma, address,
2502 pte, pmd, write_access, entry);
2503 if (unlikely(vma->vm_ops->nopfn))
2504 return do_no_pfn(mm, vma, address, pte,
2505 pmd, write_access);
2506 }
2507 return do_anonymous_page(mm, vma, address,
2508 pte, pmd, write_access);
2509 }
2510 if (pte_file(entry))
2511 return do_nonlinear_fault(mm, vma, address,
2512 pte, pmd, write_access, entry);
2513 return do_swap_page(mm, vma, address,
2514 pte, pmd, write_access, entry);
2515 }
2516
2517 ptl = pte_lockptr(mm, pmd);
2518 spin_lock(ptl);
2519 if (unlikely(!pte_same(*pte, entry)))
2520 goto unlock;
2521 if (write_access) {
2522 if (!pte_write(entry))
2523 return do_wp_page(mm, vma, address,
2524 pte, pmd, ptl, entry);
2525 entry = pte_mkdirty(entry);
2526 }
2527 entry = pte_mkyoung(entry);
2528 if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {
2529 update_mmu_cache(vma, address, entry);
2530 } else {
2531 /*
2532 * This is needed only for protection faults but the arch code
2533 * is not yet telling us if this is a protection fault or not.
2534 * This still avoids useless tlb flushes for .text page faults
2535 * with threads.
2536 */
2537 if (write_access)
2538 flush_tlb_page(vma, address);
2539 }
2540 unlock:
2541 pte_unmap_unlock(pte, ptl);
2542 return 0;
2543 }
2544
2545 void pagefault_disable(void)
2546 {
2547 current->pagefault_disabled++;
2548 /*
2549 * make sure to have issued the store before a pagefault
2550 * can hit.
2551 */
2552 barrier();
2553 }
2554 EXPORT_SYMBOL(pagefault_disable);
2555
2556 void pagefault_enable(void)
2557 {
2558 /*
2559 * make sure to issue those last loads/stores before enabling
2560 * the pagefault handler again.
2561 */
2562 barrier();
2563 current->pagefault_disabled--;
2564 }
2565 EXPORT_SYMBOL(pagefault_enable);
2566
2567 /*
2568 * By the time we get here, we already hold the mm semaphore
2569 */
2570 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2571 unsigned long address, int write_access)
2572 {
2573 pgd_t *pgd;
2574 pud_t *pud;
2575 pmd_t *pmd;
2576 pte_t *pte;
2577
2578 __set_current_state(TASK_RUNNING);
2579
2580 count_vm_event(PGFAULT);
2581
2582 if (unlikely(is_vm_hugetlb_page(vma)))
2583 return hugetlb_fault(mm, vma, address, write_access);
2584
2585 pgd = pgd_offset(mm, address);
2586 pud = pud_alloc(mm, pgd, address);
2587 if (!pud)
2588 return VM_FAULT_OOM;
2589 pmd = pmd_alloc(mm, pud, address);
2590 if (!pmd)
2591 return VM_FAULT_OOM;
2592 pte = pte_alloc_map(mm, pmd, address);
2593 if (!pte)
2594 return VM_FAULT_OOM;
2595
2596 return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
2597 }
2598
2599 #ifndef __PAGETABLE_PUD_FOLDED
2600 /*
2601 * Allocate page upper directory.
2602 * We've already handled the fast-path in-line.
2603 */
2604 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2605 {
2606 pud_t *new = pud_alloc_one(mm, address);
2607 if (!new)
2608 return -ENOMEM;
2609
2610 spin_lock(&mm->page_table_lock);
2611 if (pgd_present(*pgd)) /* Another has populated it */
2612 pud_free(mm, new);
2613 else
2614 pgd_populate(mm, pgd, new);
2615 spin_unlock(&mm->page_table_lock);
2616 return 0;
2617 }
2618 #endif /* __PAGETABLE_PUD_FOLDED */
2619
2620 #ifndef __PAGETABLE_PMD_FOLDED
2621 /*
2622 * Allocate page middle directory.
2623 * We've already handled the fast-path in-line.
2624 */
2625 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2626 {
2627 pmd_t *new = pmd_alloc_one(mm, address);
2628 if (!new)
2629 return -ENOMEM;
2630
2631 spin_lock(&mm->page_table_lock);
2632 #ifndef __ARCH_HAS_4LEVEL_HACK
2633 if (pud_present(*pud)) /* Another has populated it */
2634 pmd_free(mm, new);
2635 else
2636 pud_populate(mm, pud, new);
2637 #else
2638 if (pgd_present(*pud)) /* Another has populated it */
2639 pmd_free(mm, new);
2640 else
2641 pgd_populate(mm, pud, new);
2642 #endif /* __ARCH_HAS_4LEVEL_HACK */
2643 spin_unlock(&mm->page_table_lock);
2644 return 0;
2645 }
2646 #endif /* __PAGETABLE_PMD_FOLDED */
2647
2648 int make_pages_present(unsigned long addr, unsigned long end)
2649 {
2650 int ret, len, write;
2651 struct vm_area_struct * vma;
2652
2653 vma = find_vma(current->mm, addr);
2654 if (!vma)
2655 return -1;
2656 write = (vma->vm_flags & VM_WRITE) != 0;
2657 BUG_ON(addr >= end);
2658 BUG_ON(end > vma->vm_end);
2659 len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
2660 ret = get_user_pages(current, current->mm, addr,
2661 len, write, 0, NULL, NULL);
2662 if (ret < 0)
2663 return ret;
2664 return ret == len ? 0 : -1;
2665 }
2666
2667 #if !defined(__HAVE_ARCH_GATE_AREA)
2668
2669 #if defined(AT_SYSINFO_EHDR)
2670 static struct vm_area_struct gate_vma;
2671
2672 static int __init gate_vma_init(void)
2673 {
2674 gate_vma.vm_mm = NULL;
2675 gate_vma.vm_start = FIXADDR_USER_START;
2676 gate_vma.vm_end = FIXADDR_USER_END;
2677 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
2678 gate_vma.vm_page_prot = __P101;
2679 /*
2680 * Make sure the vDSO gets into every core dump.
2681 * Dumping its contents makes post-mortem fully interpretable later
2682 * without matching up the same kernel and hardware config to see
2683 * what PC values meant.
2684 */
2685 gate_vma.vm_flags |= VM_ALWAYSDUMP;
2686 return 0;
2687 }
2688 __initcall(gate_vma_init);
2689 #endif
2690
2691 struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
2692 {
2693 #ifdef AT_SYSINFO_EHDR
2694 return &gate_vma;
2695 #else
2696 return NULL;
2697 #endif
2698 }
2699
2700 int in_gate_area_no_task(unsigned long addr)
2701 {
2702 #ifdef AT_SYSINFO_EHDR
2703 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
2704 return 1;
2705 #endif
2706 return 0;
2707 }
2708
2709 #endif /* __HAVE_ARCH_GATE_AREA */
2710
2711 /*
2712 * Access another process' address space.
2713 * Source/target buffer must be kernel space,
2714 * Do not walk the page table directly, use get_user_pages
2715 */
2716 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
2717 {
2718 struct mm_struct *mm;
2719 struct vm_area_struct *vma;
2720 struct page *page;
2721 void *old_buf = buf;
2722
2723 mm = get_task_mm(tsk);
2724 if (!mm)
2725 return 0;
2726
2727 down_read(&mm->mmap_sem);
2728 /* ignore errors, just check how much was successfully transferred */
2729 while (len) {
2730 int bytes, ret, offset;
2731 void *maddr;
2732
2733 ret = get_user_pages(tsk, mm, addr, 1,
2734 write, 1, &page, &vma);
2735 if (ret <= 0)
2736 break;
2737
2738 bytes = len;
2739 offset = addr & (PAGE_SIZE-1);
2740 if (bytes > PAGE_SIZE-offset)
2741 bytes = PAGE_SIZE-offset;
2742
2743 maddr = kmap(page);
2744 if (write) {
2745 copy_to_user_page(vma, page, addr,
2746 maddr + offset, buf, bytes);
2747 set_page_dirty_lock(page);
2748 } else {
2749 copy_from_user_page(vma, page, addr,
2750 buf, maddr + offset, bytes);
2751 }
2752 kunmap(page);
2753 page_cache_release(page);
2754 len -= bytes;
2755 buf += bytes;
2756 addr += bytes;
2757 }
2758 up_read(&mm->mmap_sem);
2759 mmput(mm);
2760
2761 return buf - old_buf;
2762 }
2763
2764 /*
2765 * Print the name of a VMA.
2766 */
2767 void print_vma_addr(char *prefix, unsigned long ip)
2768 {
2769 struct mm_struct *mm = current->mm;
2770 struct vm_area_struct *vma;
2771
2772 /*
2773 * Do not print if we are in atomic
2774 * contexts (in exception stacks, etc.):
2775 */
2776 if (preempt_count())
2777 return;
2778
2779 down_read(&mm->mmap_sem);
2780 vma = find_vma(mm, ip);
2781 if (vma && vma->vm_file) {
2782 struct file *f = vma->vm_file;
2783 char *buf = (char *)__get_free_page(GFP_KERNEL);
2784 if (buf) {
2785 char *p, *s;
2786
2787 p = d_path(&f->f_path, buf, PAGE_SIZE);
2788 if (IS_ERR(p))
2789 p = "?";
2790 s = strrchr(p, '/');
2791 if (s)
2792 p = s+1;
2793 printk("%s%s[%lx+%lx]", prefix, p,
2794 vma->vm_start,
2795 vma->vm_end - vma->vm_start);
2796 free_page((unsigned long)buf);
2797 }
2798 }
2799 up_read(¤t->mm->mmap_sem);
2800 }
2801
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