[PATCH] mm: split highorder pages
[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/init.h>
51
52 #include <asm/pgalloc.h>
53 #include <asm/uaccess.h>
54 #include <asm/tlb.h>
55 #include <asm/tlbflush.h>
56 #include <asm/pgtable.h>
57
58 #include <linux/swapops.h>
59 #include <linux/elf.h>
60
61 #ifndef CONFIG_NEED_MULTIPLE_NODES
62 /* use the per-pgdat data instead for discontigmem - mbligh */
63 unsigned long max_mapnr;
64 struct page *mem_map;
65
66 EXPORT_SYMBOL(max_mapnr);
67 EXPORT_SYMBOL(mem_map);
68 #endif
69
70 unsigned long num_physpages;
71 /*
72  * A number of key systems in x86 including ioremap() rely on the assumption
73  * that high_memory defines the upper bound on direct map memory, then end
74  * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
75  * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
76  * and ZONE_HIGHMEM.
77  */
78 void * high_memory;
79 unsigned long vmalloc_earlyreserve;
80
81 EXPORT_SYMBOL(num_physpages);
82 EXPORT_SYMBOL(high_memory);
83 EXPORT_SYMBOL(vmalloc_earlyreserve);
84
85 int randomize_va_space __read_mostly = 1;
86
87 static int __init disable_randmaps(char *s)
88 {
89         randomize_va_space = 0;
90         return 0;
91 }
92 __setup("norandmaps", disable_randmaps);
93
94
95 /*
96  * If a p?d_bad entry is found while walking page tables, report
97  * the error, before resetting entry to p?d_none.  Usually (but
98  * very seldom) called out from the p?d_none_or_clear_bad macros.
99  */
100
101 void pgd_clear_bad(pgd_t *pgd)
102 {
103         pgd_ERROR(*pgd);
104         pgd_clear(pgd);
105 }
106
107 void pud_clear_bad(pud_t *pud)
108 {
109         pud_ERROR(*pud);
110         pud_clear(pud);
111 }
112
113 void pmd_clear_bad(pmd_t *pmd)
114 {
115         pmd_ERROR(*pmd);
116         pmd_clear(pmd);
117 }
118
119 /*
120  * Note: this doesn't free the actual pages themselves. That
121  * has been handled earlier when unmapping all the memory regions.
122  */
123 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
124 {
125         struct page *page = pmd_page(*pmd);
126         pmd_clear(pmd);
127         pte_lock_deinit(page);
128         pte_free_tlb(tlb, page);
129         dec_page_state(nr_page_table_pages);
130         tlb->mm->nr_ptes--;
131 }
132
133 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
134                                 unsigned long addr, unsigned long end,
135                                 unsigned long floor, unsigned long ceiling)
136 {
137         pmd_t *pmd;
138         unsigned long next;
139         unsigned long start;
140
141         start = addr;
142         pmd = pmd_offset(pud, addr);
143         do {
144                 next = pmd_addr_end(addr, end);
145                 if (pmd_none_or_clear_bad(pmd))
146                         continue;
147                 free_pte_range(tlb, pmd);
148         } while (pmd++, addr = next, addr != end);
149
150         start &= PUD_MASK;
151         if (start < floor)
152                 return;
153         if (ceiling) {
154                 ceiling &= PUD_MASK;
155                 if (!ceiling)
156                         return;
157         }
158         if (end - 1 > ceiling - 1)
159                 return;
160
161         pmd = pmd_offset(pud, start);
162         pud_clear(pud);
163         pmd_free_tlb(tlb, pmd);
164 }
165
166 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
167                                 unsigned long addr, unsigned long end,
168                                 unsigned long floor, unsigned long ceiling)
169 {
170         pud_t *pud;
171         unsigned long next;
172         unsigned long start;
173
174         start = addr;
175         pud = pud_offset(pgd, addr);
176         do {
177                 next = pud_addr_end(addr, end);
178                 if (pud_none_or_clear_bad(pud))
179                         continue;
180                 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
181         } while (pud++, addr = next, addr != end);
182
183         start &= PGDIR_MASK;
184         if (start < floor)
185                 return;
186         if (ceiling) {
187                 ceiling &= PGDIR_MASK;
188                 if (!ceiling)
189                         return;
190         }
191         if (end - 1 > ceiling - 1)
192                 return;
193
194         pud = pud_offset(pgd, start);
195         pgd_clear(pgd);
196         pud_free_tlb(tlb, pud);
197 }
198
199 /*
200  * This function frees user-level page tables of a process.
201  *
202  * Must be called with pagetable lock held.
203  */
204 void free_pgd_range(struct mmu_gather **tlb,
205                         unsigned long addr, unsigned long end,
206                         unsigned long floor, unsigned long ceiling)
207 {
208         pgd_t *pgd;
209         unsigned long next;
210         unsigned long start;
211
212         /*
213          * The next few lines have given us lots of grief...
214          *
215          * Why are we testing PMD* at this top level?  Because often
216          * there will be no work to do at all, and we'd prefer not to
217          * go all the way down to the bottom just to discover that.
218          *
219          * Why all these "- 1"s?  Because 0 represents both the bottom
220          * of the address space and the top of it (using -1 for the
221          * top wouldn't help much: the masks would do the wrong thing).
222          * The rule is that addr 0 and floor 0 refer to the bottom of
223          * the address space, but end 0 and ceiling 0 refer to the top
224          * Comparisons need to use "end - 1" and "ceiling - 1" (though
225          * that end 0 case should be mythical).
226          *
227          * Wherever addr is brought up or ceiling brought down, we must
228          * be careful to reject "the opposite 0" before it confuses the
229          * subsequent tests.  But what about where end is brought down
230          * by PMD_SIZE below? no, end can't go down to 0 there.
231          *
232          * Whereas we round start (addr) and ceiling down, by different
233          * masks at different levels, in order to test whether a table
234          * now has no other vmas using it, so can be freed, we don't
235          * bother to round floor or end up - the tests don't need that.
236          */
237
238         addr &= PMD_MASK;
239         if (addr < floor) {
240                 addr += PMD_SIZE;
241                 if (!addr)
242                         return;
243         }
244         if (ceiling) {
245                 ceiling &= PMD_MASK;
246                 if (!ceiling)
247                         return;
248         }
249         if (end - 1 > ceiling - 1)
250                 end -= PMD_SIZE;
251         if (addr > end - 1)
252                 return;
253
254         start = addr;
255         pgd = pgd_offset((*tlb)->mm, addr);
256         do {
257                 next = pgd_addr_end(addr, end);
258                 if (pgd_none_or_clear_bad(pgd))
259                         continue;
260                 free_pud_range(*tlb, pgd, addr, next, floor, ceiling);
261         } while (pgd++, addr = next, addr != end);
262
263         if (!(*tlb)->fullmm)
264                 flush_tlb_pgtables((*tlb)->mm, start, end);
265 }
266
267 void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
268                 unsigned long floor, unsigned long ceiling)
269 {
270         while (vma) {
271                 struct vm_area_struct *next = vma->vm_next;
272                 unsigned long addr = vma->vm_start;
273
274                 /*
275                  * Hide vma from rmap and vmtruncate before freeing pgtables
276                  */
277                 anon_vma_unlink(vma);
278                 unlink_file_vma(vma);
279
280                 if (is_hugepage_only_range(vma->vm_mm, addr, HPAGE_SIZE)) {
281                         hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
282                                 floor, next? next->vm_start: ceiling);
283                 } else {
284                         /*
285                          * Optimization: gather nearby vmas into one call down
286                          */
287                         while (next && next->vm_start <= vma->vm_end + PMD_SIZE
288                           && !is_hugepage_only_range(vma->vm_mm, next->vm_start,
289                                                         HPAGE_SIZE)) {
290                                 vma = next;
291                                 next = vma->vm_next;
292                                 anon_vma_unlink(vma);
293                                 unlink_file_vma(vma);
294                         }
295                         free_pgd_range(tlb, addr, vma->vm_end,
296                                 floor, next? next->vm_start: ceiling);
297                 }
298                 vma = next;
299         }
300 }
301
302 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
303 {
304         struct page *new = pte_alloc_one(mm, address);
305         if (!new)
306                 return -ENOMEM;
307
308         pte_lock_init(new);
309         spin_lock(&mm->page_table_lock);
310         if (pmd_present(*pmd)) {        /* Another has populated it */
311                 pte_lock_deinit(new);
312                 pte_free(new);
313         } else {
314                 mm->nr_ptes++;
315                 inc_page_state(nr_page_table_pages);
316                 pmd_populate(mm, pmd, new);
317         }
318         spin_unlock(&mm->page_table_lock);
319         return 0;
320 }
321
322 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
323 {
324         pte_t *new = pte_alloc_one_kernel(&init_mm, address);
325         if (!new)
326                 return -ENOMEM;
327
328         spin_lock(&init_mm.page_table_lock);
329         if (pmd_present(*pmd))          /* Another has populated it */
330                 pte_free_kernel(new);
331         else
332                 pmd_populate_kernel(&init_mm, pmd, new);
333         spin_unlock(&init_mm.page_table_lock);
334         return 0;
335 }
336
337 static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
338 {
339         if (file_rss)
340                 add_mm_counter(mm, file_rss, file_rss);
341         if (anon_rss)
342                 add_mm_counter(mm, anon_rss, anon_rss);
343 }
344
345 /*
346  * This function is called to print an error when a bad pte
347  * is found. For example, we might have a PFN-mapped pte in
348  * a region that doesn't allow it.
349  *
350  * The calling function must still handle the error.
351  */
352 void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr)
353 {
354         printk(KERN_ERR "Bad pte = %08llx, process = %s, "
355                         "vm_flags = %lx, vaddr = %lx\n",
356                 (long long)pte_val(pte),
357                 (vma->vm_mm == current->mm ? current->comm : "???"),
358                 vma->vm_flags, vaddr);
359         dump_stack();
360 }
361
362 static inline int is_cow_mapping(unsigned int flags)
363 {
364         return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
365 }
366
367 /*
368  * This function gets the "struct page" associated with a pte.
369  *
370  * NOTE! Some mappings do not have "struct pages". A raw PFN mapping
371  * will have each page table entry just pointing to a raw page frame
372  * number, and as far as the VM layer is concerned, those do not have
373  * pages associated with them - even if the PFN might point to memory
374  * that otherwise is perfectly fine and has a "struct page".
375  *
376  * The way we recognize those mappings is through the rules set up
377  * by "remap_pfn_range()": the vma will have the VM_PFNMAP bit set,
378  * and the vm_pgoff will point to the first PFN mapped: thus every
379  * page that is a raw mapping will always honor the rule
380  *
381  *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
382  *
383  * and if that isn't true, the page has been COW'ed (in which case it
384  * _does_ have a "struct page" associated with it even if it is in a
385  * VM_PFNMAP range).
386  */
387 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
388 {
389         unsigned long pfn = pte_pfn(pte);
390
391         if (vma->vm_flags & VM_PFNMAP) {
392                 unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT;
393                 if (pfn == vma->vm_pgoff + off)
394                         return NULL;
395                 if (!is_cow_mapping(vma->vm_flags))
396                         return NULL;
397         }
398
399         /*
400          * Add some anal sanity checks for now. Eventually,
401          * we should just do "return pfn_to_page(pfn)", but
402          * in the meantime we check that we get a valid pfn,
403          * and that the resulting page looks ok.
404          *
405          * Remove this test eventually!
406          */
407         if (unlikely(!pfn_valid(pfn))) {
408                 print_bad_pte(vma, pte, addr);
409                 return NULL;
410         }
411
412         /*
413          * NOTE! We still have PageReserved() pages in the page 
414          * tables. 
415          *
416          * The PAGE_ZERO() pages and various VDSO mappings can
417          * cause them to exist.
418          */
419         return pfn_to_page(pfn);
420 }
421
422 /*
423  * copy one vm_area from one task to the other. Assumes the page tables
424  * already present in the new task to be cleared in the whole range
425  * covered by this vma.
426  */
427
428 static inline void
429 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
430                 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
431                 unsigned long addr, int *rss)
432 {
433         unsigned long vm_flags = vma->vm_flags;
434         pte_t pte = *src_pte;
435         struct page *page;
436
437         /* pte contains position in swap or file, so copy. */
438         if (unlikely(!pte_present(pte))) {
439                 if (!pte_file(pte)) {
440                         swap_duplicate(pte_to_swp_entry(pte));
441                         /* make sure dst_mm is on swapoff's mmlist. */
442                         if (unlikely(list_empty(&dst_mm->mmlist))) {
443                                 spin_lock(&mmlist_lock);
444                                 if (list_empty(&dst_mm->mmlist))
445                                         list_add(&dst_mm->mmlist,
446                                                  &src_mm->mmlist);
447                                 spin_unlock(&mmlist_lock);
448                         }
449                 }
450                 goto out_set_pte;
451         }
452
453         /*
454          * If it's a COW mapping, write protect it both
455          * in the parent and the child
456          */
457         if (is_cow_mapping(vm_flags)) {
458                 ptep_set_wrprotect(src_mm, addr, src_pte);
459                 pte = *src_pte;
460         }
461
462         /*
463          * If it's a shared mapping, mark it clean in
464          * the child
465          */
466         if (vm_flags & VM_SHARED)
467                 pte = pte_mkclean(pte);
468         pte = pte_mkold(pte);
469
470         page = vm_normal_page(vma, addr, pte);
471         if (page) {
472                 get_page(page);
473                 page_dup_rmap(page);
474                 rss[!!PageAnon(page)]++;
475         }
476
477 out_set_pte:
478         set_pte_at(dst_mm, addr, dst_pte, pte);
479 }
480
481 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
482                 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
483                 unsigned long addr, unsigned long end)
484 {
485         pte_t *src_pte, *dst_pte;
486         spinlock_t *src_ptl, *dst_ptl;
487         int progress = 0;
488         int rss[2];
489
490 again:
491         rss[1] = rss[0] = 0;
492         dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
493         if (!dst_pte)
494                 return -ENOMEM;
495         src_pte = pte_offset_map_nested(src_pmd, addr);
496         src_ptl = pte_lockptr(src_mm, src_pmd);
497         spin_lock(src_ptl);
498
499         do {
500                 /*
501                  * We are holding two locks at this point - either of them
502                  * could generate latencies in another task on another CPU.
503                  */
504                 if (progress >= 32) {
505                         progress = 0;
506                         if (need_resched() ||
507                             need_lockbreak(src_ptl) ||
508                             need_lockbreak(dst_ptl))
509                                 break;
510                 }
511                 if (pte_none(*src_pte)) {
512                         progress++;
513                         continue;
514                 }
515                 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
516                 progress += 8;
517         } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
518
519         spin_unlock(src_ptl);
520         pte_unmap_nested(src_pte - 1);
521         add_mm_rss(dst_mm, rss[0], rss[1]);
522         pte_unmap_unlock(dst_pte - 1, dst_ptl);
523         cond_resched();
524         if (addr != end)
525                 goto again;
526         return 0;
527 }
528
529 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
530                 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
531                 unsigned long addr, unsigned long end)
532 {
533         pmd_t *src_pmd, *dst_pmd;
534         unsigned long next;
535
536         dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
537         if (!dst_pmd)
538                 return -ENOMEM;
539         src_pmd = pmd_offset(src_pud, addr);
540         do {
541                 next = pmd_addr_end(addr, end);
542                 if (pmd_none_or_clear_bad(src_pmd))
543                         continue;
544                 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
545                                                 vma, addr, next))
546                         return -ENOMEM;
547         } while (dst_pmd++, src_pmd++, addr = next, addr != end);
548         return 0;
549 }
550
551 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
552                 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
553                 unsigned long addr, unsigned long end)
554 {
555         pud_t *src_pud, *dst_pud;
556         unsigned long next;
557
558         dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
559         if (!dst_pud)
560                 return -ENOMEM;
561         src_pud = pud_offset(src_pgd, addr);
562         do {
563                 next = pud_addr_end(addr, end);
564                 if (pud_none_or_clear_bad(src_pud))
565                         continue;
566                 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
567                                                 vma, addr, next))
568                         return -ENOMEM;
569         } while (dst_pud++, src_pud++, addr = next, addr != end);
570         return 0;
571 }
572
573 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
574                 struct vm_area_struct *vma)
575 {
576         pgd_t *src_pgd, *dst_pgd;
577         unsigned long next;
578         unsigned long addr = vma->vm_start;
579         unsigned long end = vma->vm_end;
580
581         /*
582          * Don't copy ptes where a page fault will fill them correctly.
583          * Fork becomes much lighter when there are big shared or private
584          * readonly mappings. The tradeoff is that copy_page_range is more
585          * efficient than faulting.
586          */
587         if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
588                 if (!vma->anon_vma)
589                         return 0;
590         }
591
592         if (is_vm_hugetlb_page(vma))
593                 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
594
595         dst_pgd = pgd_offset(dst_mm, addr);
596         src_pgd = pgd_offset(src_mm, addr);
597         do {
598                 next = pgd_addr_end(addr, end);
599                 if (pgd_none_or_clear_bad(src_pgd))
600                         continue;
601                 if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
602                                                 vma, addr, next))
603                         return -ENOMEM;
604         } while (dst_pgd++, src_pgd++, addr = next, addr != end);
605         return 0;
606 }
607
608 static unsigned long zap_pte_range(struct mmu_gather *tlb,
609                                 struct vm_area_struct *vma, pmd_t *pmd,
610                                 unsigned long addr, unsigned long end,
611                                 long *zap_work, struct zap_details *details)
612 {
613         struct mm_struct *mm = tlb->mm;
614         pte_t *pte;
615         spinlock_t *ptl;
616         int file_rss = 0;
617         int anon_rss = 0;
618
619         pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
620         do {
621                 pte_t ptent = *pte;
622                 if (pte_none(ptent)) {
623                         (*zap_work)--;
624                         continue;
625                 }
626
627                 (*zap_work) -= PAGE_SIZE;
628
629                 if (pte_present(ptent)) {
630                         struct page *page;
631
632                         page = vm_normal_page(vma, addr, ptent);
633                         if (unlikely(details) && page) {
634                                 /*
635                                  * unmap_shared_mapping_pages() wants to
636                                  * invalidate cache without truncating:
637                                  * unmap shared but keep private pages.
638                                  */
639                                 if (details->check_mapping &&
640                                     details->check_mapping != page->mapping)
641                                         continue;
642                                 /*
643                                  * Each page->index must be checked when
644                                  * invalidating or truncating nonlinear.
645                                  */
646                                 if (details->nonlinear_vma &&
647                                     (page->index < details->first_index ||
648                                      page->index > details->last_index))
649                                         continue;
650                         }
651                         ptent = ptep_get_and_clear_full(mm, addr, pte,
652                                                         tlb->fullmm);
653                         tlb_remove_tlb_entry(tlb, pte, addr);
654                         if (unlikely(!page))
655                                 continue;
656                         if (unlikely(details) && details->nonlinear_vma
657                             && linear_page_index(details->nonlinear_vma,
658                                                 addr) != page->index)
659                                 set_pte_at(mm, addr, pte,
660                                            pgoff_to_pte(page->index));
661                         if (PageAnon(page))
662                                 anon_rss--;
663                         else {
664                                 if (pte_dirty(ptent))
665                                         set_page_dirty(page);
666                                 if (pte_young(ptent))
667                                         mark_page_accessed(page);
668                                 file_rss--;
669                         }
670                         page_remove_rmap(page);
671                         tlb_remove_page(tlb, page);
672                         continue;
673                 }
674                 /*
675                  * If details->check_mapping, we leave swap entries;
676                  * if details->nonlinear_vma, we leave file entries.
677                  */
678                 if (unlikely(details))
679                         continue;
680                 if (!pte_file(ptent))
681                         free_swap_and_cache(pte_to_swp_entry(ptent));
682                 pte_clear_full(mm, addr, pte, tlb->fullmm);
683         } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
684
685         add_mm_rss(mm, file_rss, anon_rss);
686         pte_unmap_unlock(pte - 1, ptl);
687
688         return addr;
689 }
690
691 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
692                                 struct vm_area_struct *vma, pud_t *pud,
693                                 unsigned long addr, unsigned long end,
694                                 long *zap_work, struct zap_details *details)
695 {
696         pmd_t *pmd;
697         unsigned long next;
698
699         pmd = pmd_offset(pud, addr);
700         do {
701                 next = pmd_addr_end(addr, end);
702                 if (pmd_none_or_clear_bad(pmd)) {
703                         (*zap_work)--;
704                         continue;
705                 }
706                 next = zap_pte_range(tlb, vma, pmd, addr, next,
707                                                 zap_work, details);
708         } while (pmd++, addr = next, (addr != end && *zap_work > 0));
709
710         return addr;
711 }
712
713 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
714                                 struct vm_area_struct *vma, pgd_t *pgd,
715                                 unsigned long addr, unsigned long end,
716                                 long *zap_work, struct zap_details *details)
717 {
718         pud_t *pud;
719         unsigned long next;
720
721         pud = pud_offset(pgd, addr);
722         do {
723                 next = pud_addr_end(addr, end);
724                 if (pud_none_or_clear_bad(pud)) {
725                         (*zap_work)--;
726                         continue;
727                 }
728                 next = zap_pmd_range(tlb, vma, pud, addr, next,
729                                                 zap_work, details);
730         } while (pud++, addr = next, (addr != end && *zap_work > 0));
731
732         return addr;
733 }
734
735 static unsigned long unmap_page_range(struct mmu_gather *tlb,
736                                 struct vm_area_struct *vma,
737                                 unsigned long addr, unsigned long end,
738                                 long *zap_work, struct zap_details *details)
739 {
740         pgd_t *pgd;
741         unsigned long next;
742
743         if (details && !details->check_mapping && !details->nonlinear_vma)
744                 details = NULL;
745
746         BUG_ON(addr >= end);
747         tlb_start_vma(tlb, vma);
748         pgd = pgd_offset(vma->vm_mm, addr);
749         do {
750                 next = pgd_addr_end(addr, end);
751                 if (pgd_none_or_clear_bad(pgd)) {
752                         (*zap_work)--;
753                         continue;
754                 }
755                 next = zap_pud_range(tlb, vma, pgd, addr, next,
756                                                 zap_work, details);
757         } while (pgd++, addr = next, (addr != end && *zap_work > 0));
758         tlb_end_vma(tlb, vma);
759
760         return addr;
761 }
762
763 #ifdef CONFIG_PREEMPT
764 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
765 #else
766 /* No preempt: go for improved straight-line efficiency */
767 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
768 #endif
769
770 /**
771  * unmap_vmas - unmap a range of memory covered by a list of vma's
772  * @tlbp: address of the caller's struct mmu_gather
773  * @vma: the starting vma
774  * @start_addr: virtual address at which to start unmapping
775  * @end_addr: virtual address at which to end unmapping
776  * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
777  * @details: details of nonlinear truncation or shared cache invalidation
778  *
779  * Returns the end address of the unmapping (restart addr if interrupted).
780  *
781  * Unmap all pages in the vma list.
782  *
783  * We aim to not hold locks for too long (for scheduling latency reasons).
784  * So zap pages in ZAP_BLOCK_SIZE bytecounts.  This means we need to
785  * return the ending mmu_gather to the caller.
786  *
787  * Only addresses between `start' and `end' will be unmapped.
788  *
789  * The VMA list must be sorted in ascending virtual address order.
790  *
791  * unmap_vmas() assumes that the caller will flush the whole unmapped address
792  * range after unmap_vmas() returns.  So the only responsibility here is to
793  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
794  * drops the lock and schedules.
795  */
796 unsigned long unmap_vmas(struct mmu_gather **tlbp,
797                 struct vm_area_struct *vma, unsigned long start_addr,
798                 unsigned long end_addr, unsigned long *nr_accounted,
799                 struct zap_details *details)
800 {
801         long zap_work = ZAP_BLOCK_SIZE;
802         unsigned long tlb_start = 0;    /* For tlb_finish_mmu */
803         int tlb_start_valid = 0;
804         unsigned long start = start_addr;
805         spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
806         int fullmm = (*tlbp)->fullmm;
807
808         for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
809                 unsigned long end;
810
811                 start = max(vma->vm_start, start_addr);
812                 if (start >= vma->vm_end)
813                         continue;
814                 end = min(vma->vm_end, end_addr);
815                 if (end <= vma->vm_start)
816                         continue;
817
818                 if (vma->vm_flags & VM_ACCOUNT)
819                         *nr_accounted += (end - start) >> PAGE_SHIFT;
820
821                 while (start != end) {
822                         if (!tlb_start_valid) {
823                                 tlb_start = start;
824                                 tlb_start_valid = 1;
825                         }
826
827                         if (unlikely(is_vm_hugetlb_page(vma))) {
828                                 unmap_hugepage_range(vma, start, end);
829                                 zap_work -= (end - start) /
830                                                 (HPAGE_SIZE / PAGE_SIZE);
831                                 start = end;
832                         } else
833                                 start = unmap_page_range(*tlbp, vma,
834                                                 start, end, &zap_work, details);
835
836                         if (zap_work > 0) {
837                                 BUG_ON(start != end);
838                                 break;
839                         }
840
841                         tlb_finish_mmu(*tlbp, tlb_start, start);
842
843                         if (need_resched() ||
844                                 (i_mmap_lock && need_lockbreak(i_mmap_lock))) {
845                                 if (i_mmap_lock) {
846                                         *tlbp = NULL;
847                                         goto out;
848                                 }
849                                 cond_resched();
850                         }
851
852                         *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
853                         tlb_start_valid = 0;
854                         zap_work = ZAP_BLOCK_SIZE;
855                 }
856         }
857 out:
858         return start;   /* which is now the end (or restart) address */
859 }
860
861 /**
862  * zap_page_range - remove user pages in a given range
863  * @vma: vm_area_struct holding the applicable pages
864  * @address: starting address of pages to zap
865  * @size: number of bytes to zap
866  * @details: details of nonlinear truncation or shared cache invalidation
867  */
868 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
869                 unsigned long size, struct zap_details *details)
870 {
871         struct mm_struct *mm = vma->vm_mm;
872         struct mmu_gather *tlb;
873         unsigned long end = address + size;
874         unsigned long nr_accounted = 0;
875
876         lru_add_drain();
877         tlb = tlb_gather_mmu(mm, 0);
878         update_hiwater_rss(mm);
879         end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
880         if (tlb)
881                 tlb_finish_mmu(tlb, address, end);
882         return end;
883 }
884
885 /*
886  * Do a quick page-table lookup for a single page.
887  */
888 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
889                         unsigned int flags)
890 {
891         pgd_t *pgd;
892         pud_t *pud;
893         pmd_t *pmd;
894         pte_t *ptep, pte;
895         spinlock_t *ptl;
896         struct page *page;
897         struct mm_struct *mm = vma->vm_mm;
898
899         page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
900         if (!IS_ERR(page)) {
901                 BUG_ON(flags & FOLL_GET);
902                 goto out;
903         }
904
905         page = NULL;
906         pgd = pgd_offset(mm, address);
907         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
908                 goto no_page_table;
909
910         pud = pud_offset(pgd, address);
911         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
912                 goto no_page_table;
913         
914         pmd = pmd_offset(pud, address);
915         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
916                 goto no_page_table;
917
918         if (pmd_huge(*pmd)) {
919                 BUG_ON(flags & FOLL_GET);
920                 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
921                 goto out;
922         }
923
924         ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
925         if (!ptep)
926                 goto out;
927
928         pte = *ptep;
929         if (!pte_present(pte))
930                 goto unlock;
931         if ((flags & FOLL_WRITE) && !pte_write(pte))
932                 goto unlock;
933         page = vm_normal_page(vma, address, pte);
934         if (unlikely(!page))
935                 goto unlock;
936
937         if (flags & FOLL_GET)
938                 get_page(page);
939         if (flags & FOLL_TOUCH) {
940                 if ((flags & FOLL_WRITE) &&
941                     !pte_dirty(pte) && !PageDirty(page))
942                         set_page_dirty(page);
943                 mark_page_accessed(page);
944         }
945 unlock:
946         pte_unmap_unlock(ptep, ptl);
947 out:
948         return page;
949
950 no_page_table:
951         /*
952          * When core dumping an enormous anonymous area that nobody
953          * has touched so far, we don't want to allocate page tables.
954          */
955         if (flags & FOLL_ANON) {
956                 page = ZERO_PAGE(address);
957                 if (flags & FOLL_GET)
958                         get_page(page);
959                 BUG_ON(flags & FOLL_WRITE);
960         }
961         return page;
962 }
963
964 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
965                 unsigned long start, int len, int write, int force,
966                 struct page **pages, struct vm_area_struct **vmas)
967 {
968         int i;
969         unsigned int vm_flags;
970
971         /* 
972          * Require read or write permissions.
973          * If 'force' is set, we only require the "MAY" flags.
974          */
975         vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
976         vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
977         i = 0;
978
979         do {
980                 struct vm_area_struct *vma;
981                 unsigned int foll_flags;
982
983                 vma = find_extend_vma(mm, start);
984                 if (!vma && in_gate_area(tsk, start)) {
985                         unsigned long pg = start & PAGE_MASK;
986                         struct vm_area_struct *gate_vma = get_gate_vma(tsk);
987                         pgd_t *pgd;
988                         pud_t *pud;
989                         pmd_t *pmd;
990                         pte_t *pte;
991                         if (write) /* user gate pages are read-only */
992                                 return i ? : -EFAULT;
993                         if (pg > TASK_SIZE)
994                                 pgd = pgd_offset_k(pg);
995                         else
996                                 pgd = pgd_offset_gate(mm, pg);
997                         BUG_ON(pgd_none(*pgd));
998                         pud = pud_offset(pgd, pg);
999                         BUG_ON(pud_none(*pud));
1000                         pmd = pmd_offset(pud, pg);
1001                         if (pmd_none(*pmd))
1002                                 return i ? : -EFAULT;
1003                         pte = pte_offset_map(pmd, pg);
1004                         if (pte_none(*pte)) {
1005                                 pte_unmap(pte);
1006                                 return i ? : -EFAULT;
1007                         }
1008                         if (pages) {
1009                                 struct page *page = vm_normal_page(gate_vma, start, *pte);
1010                                 pages[i] = page;
1011                                 if (page)
1012                                         get_page(page);
1013                         }
1014                         pte_unmap(pte);
1015                         if (vmas)
1016                                 vmas[i] = gate_vma;
1017                         i++;
1018                         start += PAGE_SIZE;
1019                         len--;
1020                         continue;
1021                 }
1022
1023                 if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
1024                                 || !(vm_flags & vma->vm_flags))
1025                         return i ? : -EFAULT;
1026
1027                 if (is_vm_hugetlb_page(vma)) {
1028                         i = follow_hugetlb_page(mm, vma, pages, vmas,
1029                                                 &start, &len, i);
1030                         continue;
1031                 }
1032
1033                 foll_flags = FOLL_TOUCH;
1034                 if (pages)
1035                         foll_flags |= FOLL_GET;
1036                 if (!write && !(vma->vm_flags & VM_LOCKED) &&
1037                     (!vma->vm_ops || !vma->vm_ops->nopage))
1038                         foll_flags |= FOLL_ANON;
1039
1040                 do {
1041                         struct page *page;
1042
1043                         if (write)
1044                                 foll_flags |= FOLL_WRITE;
1045
1046                         cond_resched();
1047                         while (!(page = follow_page(vma, start, foll_flags))) {
1048                                 int ret;
1049                                 ret = __handle_mm_fault(mm, vma, start,
1050                                                 foll_flags & FOLL_WRITE);
1051                                 /*
1052                                  * The VM_FAULT_WRITE bit tells us that do_wp_page has
1053                                  * broken COW when necessary, even if maybe_mkwrite
1054                                  * decided not to set pte_write. We can thus safely do
1055                                  * subsequent page lookups as if they were reads.
1056                                  */
1057                                 if (ret & VM_FAULT_WRITE)
1058                                         foll_flags &= ~FOLL_WRITE;
1059                                 
1060                                 switch (ret & ~VM_FAULT_WRITE) {
1061                                 case VM_FAULT_MINOR:
1062                                         tsk->min_flt++;
1063                                         break;
1064                                 case VM_FAULT_MAJOR:
1065                                         tsk->maj_flt++;
1066                                         break;
1067                                 case VM_FAULT_SIGBUS:
1068                                         return i ? i : -EFAULT;
1069                                 case VM_FAULT_OOM:
1070                                         return i ? i : -ENOMEM;
1071                                 default:
1072                                         BUG();
1073                                 }
1074                         }
1075                         if (pages) {
1076                                 pages[i] = page;
1077                                 flush_dcache_page(page);
1078                         }
1079                         if (vmas)
1080                                 vmas[i] = vma;
1081                         i++;
1082                         start += PAGE_SIZE;
1083                         len--;
1084                 } while (len && start < vma->vm_end);
1085         } while (len);
1086         return i;
1087 }
1088 EXPORT_SYMBOL(get_user_pages);
1089
1090 static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1091                         unsigned long addr, unsigned long end, pgprot_t prot)
1092 {
1093         pte_t *pte;
1094         spinlock_t *ptl;
1095
1096         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1097         if (!pte)
1098                 return -ENOMEM;
1099         do {
1100                 struct page *page = ZERO_PAGE(addr);
1101                 pte_t zero_pte = pte_wrprotect(mk_pte(page, prot));
1102                 page_cache_get(page);
1103                 page_add_file_rmap(page);
1104                 inc_mm_counter(mm, file_rss);
1105                 BUG_ON(!pte_none(*pte));
1106                 set_pte_at(mm, addr, pte, zero_pte);
1107         } while (pte++, addr += PAGE_SIZE, addr != end);
1108         pte_unmap_unlock(pte - 1, ptl);
1109         return 0;
1110 }
1111
1112 static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud,
1113                         unsigned long addr, unsigned long end, pgprot_t prot)
1114 {
1115         pmd_t *pmd;
1116         unsigned long next;
1117
1118         pmd = pmd_alloc(mm, pud, addr);
1119         if (!pmd)
1120                 return -ENOMEM;
1121         do {
1122                 next = pmd_addr_end(addr, end);
1123                 if (zeromap_pte_range(mm, pmd, addr, next, prot))
1124                         return -ENOMEM;
1125         } while (pmd++, addr = next, addr != end);
1126         return 0;
1127 }
1128
1129 static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1130                         unsigned long addr, unsigned long end, pgprot_t prot)
1131 {
1132         pud_t *pud;
1133         unsigned long next;
1134
1135         pud = pud_alloc(mm, pgd, addr);
1136         if (!pud)
1137                 return -ENOMEM;
1138         do {
1139                 next = pud_addr_end(addr, end);
1140                 if (zeromap_pmd_range(mm, pud, addr, next, prot))
1141                         return -ENOMEM;
1142         } while (pud++, addr = next, addr != end);
1143         return 0;
1144 }
1145
1146 int zeromap_page_range(struct vm_area_struct *vma,
1147                         unsigned long addr, unsigned long size, pgprot_t prot)
1148 {
1149         pgd_t *pgd;
1150         unsigned long next;
1151         unsigned long end = addr + size;
1152         struct mm_struct *mm = vma->vm_mm;
1153         int err;
1154
1155         BUG_ON(addr >= end);
1156         pgd = pgd_offset(mm, addr);
1157         flush_cache_range(vma, addr, end);
1158         do {
1159                 next = pgd_addr_end(addr, end);
1160                 err = zeromap_pud_range(mm, pgd, addr, next, prot);
1161                 if (err)
1162                         break;
1163         } while (pgd++, addr = next, addr != end);
1164         return err;
1165 }
1166
1167 pte_t * fastcall get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl)
1168 {
1169         pgd_t * pgd = pgd_offset(mm, addr);
1170         pud_t * pud = pud_alloc(mm, pgd, addr);
1171         if (pud) {
1172                 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1173                 if (pmd)
1174                         return pte_alloc_map_lock(mm, pmd, addr, ptl);
1175         }
1176         return NULL;
1177 }
1178
1179 /*
1180  * This is the old fallback for page remapping.
1181  *
1182  * For historical reasons, it only allows reserved pages. Only
1183  * old drivers should use this, and they needed to mark their
1184  * pages reserved for the old functions anyway.
1185  */
1186 static int insert_page(struct mm_struct *mm, unsigned long addr, struct page *page, pgprot_t prot)
1187 {
1188         int retval;
1189         pte_t *pte;
1190         spinlock_t *ptl;  
1191
1192         retval = -EINVAL;
1193         if (PageAnon(page))
1194                 goto out;
1195         retval = -ENOMEM;
1196         flush_dcache_page(page);
1197         pte = get_locked_pte(mm, addr, &ptl);
1198         if (!pte)
1199                 goto out;
1200         retval = -EBUSY;
1201         if (!pte_none(*pte))
1202                 goto out_unlock;
1203
1204         /* Ok, finally just insert the thing.. */
1205         get_page(page);
1206         inc_mm_counter(mm, file_rss);
1207         page_add_file_rmap(page);
1208         set_pte_at(mm, addr, pte, mk_pte(page, prot));
1209
1210         retval = 0;
1211 out_unlock:
1212         pte_unmap_unlock(pte, ptl);
1213 out:
1214         return retval;
1215 }
1216
1217 /*
1218  * This allows drivers to insert individual pages they've allocated
1219  * into a user vma.
1220  *
1221  * The page has to be a nice clean _individual_ kernel allocation.
1222  * If you allocate a compound page, you need to have marked it as
1223  * such (__GFP_COMP), or manually just split the page up yourself
1224  * (see split_page()).
1225  *
1226  * NOTE! Traditionally this was done with "remap_pfn_range()" which
1227  * took an arbitrary page protection parameter. This doesn't allow
1228  * that. Your vma protection will have to be set up correctly, which
1229  * means that if you want a shared writable mapping, you'd better
1230  * ask for a shared writable mapping!
1231  *
1232  * The page does not need to be reserved.
1233  */
1234 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page *page)
1235 {
1236         if (addr < vma->vm_start || addr >= vma->vm_end)
1237                 return -EFAULT;
1238         if (!page_count(page))
1239                 return -EINVAL;
1240         vma->vm_flags |= VM_INSERTPAGE;
1241         return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
1242 }
1243 EXPORT_SYMBOL(vm_insert_page);
1244
1245 /*
1246  * maps a range of physical memory into the requested pages. the old
1247  * mappings are removed. any references to nonexistent pages results
1248  * in null mappings (currently treated as "copy-on-access")
1249  */
1250 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1251                         unsigned long addr, unsigned long end,
1252                         unsigned long pfn, pgprot_t prot)
1253 {
1254         pte_t *pte;
1255         spinlock_t *ptl;
1256
1257         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1258         if (!pte)
1259                 return -ENOMEM;
1260         do {
1261                 BUG_ON(!pte_none(*pte));
1262                 set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
1263                 pfn++;
1264         } while (pte++, addr += PAGE_SIZE, addr != end);
1265         pte_unmap_unlock(pte - 1, ptl);
1266         return 0;
1267 }
1268
1269 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1270                         unsigned long addr, unsigned long end,
1271                         unsigned long pfn, pgprot_t prot)
1272 {
1273         pmd_t *pmd;
1274         unsigned long next;
1275
1276         pfn -= addr >> PAGE_SHIFT;
1277         pmd = pmd_alloc(mm, pud, addr);
1278         if (!pmd)
1279                 return -ENOMEM;
1280         do {
1281                 next = pmd_addr_end(addr, end);
1282                 if (remap_pte_range(mm, pmd, addr, next,
1283                                 pfn + (addr >> PAGE_SHIFT), prot))
1284                         return -ENOMEM;
1285         } while (pmd++, addr = next, addr != end);
1286         return 0;
1287 }
1288
1289 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1290                         unsigned long addr, unsigned long end,
1291                         unsigned long pfn, pgprot_t prot)
1292 {
1293         pud_t *pud;
1294         unsigned long next;
1295
1296         pfn -= addr >> PAGE_SHIFT;
1297         pud = pud_alloc(mm, pgd, addr);
1298         if (!pud)
1299                 return -ENOMEM;
1300         do {
1301                 next = pud_addr_end(addr, end);
1302                 if (remap_pmd_range(mm, pud, addr, next,
1303                                 pfn + (addr >> PAGE_SHIFT), prot))
1304                         return -ENOMEM;
1305         } while (pud++, addr = next, addr != end);
1306         return 0;
1307 }
1308
1309 /*  Note: this is only safe if the mm semaphore is held when called. */
1310 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1311                     unsigned long pfn, unsigned long size, pgprot_t prot)
1312 {
1313         pgd_t *pgd;
1314         unsigned long next;
1315         unsigned long end = addr + PAGE_ALIGN(size);
1316         struct mm_struct *mm = vma->vm_mm;
1317         int err;
1318
1319         /*
1320          * Physically remapped pages are special. Tell the
1321          * rest of the world about it:
1322          *   VM_IO tells people not to look at these pages
1323          *      (accesses can have side effects).
1324          *   VM_RESERVED is specified all over the place, because
1325          *      in 2.4 it kept swapout's vma scan off this vma; but
1326          *      in 2.6 the LRU scan won't even find its pages, so this
1327          *      flag means no more than count its pages in reserved_vm,
1328          *      and omit it from core dump, even when VM_IO turned off.
1329          *   VM_PFNMAP tells the core MM that the base pages are just
1330          *      raw PFN mappings, and do not have a "struct page" associated
1331          *      with them.
1332          *
1333          * There's a horrible special case to handle copy-on-write
1334          * behaviour that some programs depend on. We mark the "original"
1335          * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1336          */
1337         if (is_cow_mapping(vma->vm_flags)) {
1338                 if (addr != vma->vm_start || end != vma->vm_end)
1339                         return -EINVAL;
1340                 vma->vm_pgoff = pfn;
1341         }
1342
1343         vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1344
1345         BUG_ON(addr >= end);
1346         pfn -= addr >> PAGE_SHIFT;
1347         pgd = pgd_offset(mm, addr);
1348         flush_cache_range(vma, addr, end);
1349         do {
1350                 next = pgd_addr_end(addr, end);
1351                 err = remap_pud_range(mm, pgd, addr, next,
1352                                 pfn + (addr >> PAGE_SHIFT), prot);
1353                 if (err)
1354                         break;
1355         } while (pgd++, addr = next, addr != end);
1356         return err;
1357 }
1358 EXPORT_SYMBOL(remap_pfn_range);
1359
1360 /*
1361  * handle_pte_fault chooses page fault handler according to an entry
1362  * which was read non-atomically.  Before making any commitment, on
1363  * those architectures or configurations (e.g. i386 with PAE) which
1364  * might give a mix of unmatched parts, do_swap_page and do_file_page
1365  * must check under lock before unmapping the pte and proceeding
1366  * (but do_wp_page is only called after already making such a check;
1367  * and do_anonymous_page and do_no_page can safely check later on).
1368  */
1369 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1370                                 pte_t *page_table, pte_t orig_pte)
1371 {
1372         int same = 1;
1373 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1374         if (sizeof(pte_t) > sizeof(unsigned long)) {
1375                 spinlock_t *ptl = pte_lockptr(mm, pmd);
1376                 spin_lock(ptl);
1377                 same = pte_same(*page_table, orig_pte);
1378                 spin_unlock(ptl);
1379         }
1380 #endif
1381         pte_unmap(page_table);
1382         return same;
1383 }
1384
1385 /*
1386  * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
1387  * servicing faults for write access.  In the normal case, do always want
1388  * pte_mkwrite.  But get_user_pages can cause write faults for mappings
1389  * that do not have writing enabled, when used by access_process_vm.
1390  */
1391 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
1392 {
1393         if (likely(vma->vm_flags & VM_WRITE))
1394                 pte = pte_mkwrite(pte);
1395         return pte;
1396 }
1397
1398 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va)
1399 {
1400         /*
1401          * If the source page was a PFN mapping, we don't have
1402          * a "struct page" for it. We do a best-effort copy by
1403          * just copying from the original user address. If that
1404          * fails, we just zero-fill it. Live with it.
1405          */
1406         if (unlikely(!src)) {
1407                 void *kaddr = kmap_atomic(dst, KM_USER0);
1408                 void __user *uaddr = (void __user *)(va & PAGE_MASK);
1409
1410                 /*
1411                  * This really shouldn't fail, because the page is there
1412                  * in the page tables. But it might just be unreadable,
1413                  * in which case we just give up and fill the result with
1414                  * zeroes.
1415                  */
1416                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1417                         memset(kaddr, 0, PAGE_SIZE);
1418                 kunmap_atomic(kaddr, KM_USER0);
1419                 return;
1420                 
1421         }
1422         copy_user_highpage(dst, src, va);
1423 }
1424
1425 /*
1426  * This routine handles present pages, when users try to write
1427  * to a shared page. It is done by copying the page to a new address
1428  * and decrementing the shared-page counter for the old page.
1429  *
1430  * Note that this routine assumes that the protection checks have been
1431  * done by the caller (the low-level page fault routine in most cases).
1432  * Thus we can safely just mark it writable once we've done any necessary
1433  * COW.
1434  *
1435  * We also mark the page dirty at this point even though the page will
1436  * change only once the write actually happens. This avoids a few races,
1437  * and potentially makes it more efficient.
1438  *
1439  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1440  * but allow concurrent faults), with pte both mapped and locked.
1441  * We return with mmap_sem still held, but pte unmapped and unlocked.
1442  */
1443 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1444                 unsigned long address, pte_t *page_table, pmd_t *pmd,
1445                 spinlock_t *ptl, pte_t orig_pte)
1446 {
1447         struct page *old_page, *new_page;
1448         pte_t entry;
1449         int ret = VM_FAULT_MINOR;
1450
1451         old_page = vm_normal_page(vma, address, orig_pte);
1452         if (!old_page)
1453                 goto gotten;
1454
1455         if (PageAnon(old_page) && !TestSetPageLocked(old_page)) {
1456                 int reuse = can_share_swap_page(old_page);
1457                 unlock_page(old_page);
1458                 if (reuse) {
1459                         flush_cache_page(vma, address, pte_pfn(orig_pte));
1460                         entry = pte_mkyoung(orig_pte);
1461                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1462                         ptep_set_access_flags(vma, address, page_table, entry, 1);
1463                         update_mmu_cache(vma, address, entry);
1464                         lazy_mmu_prot_update(entry);
1465                         ret |= VM_FAULT_WRITE;
1466                         goto unlock;
1467                 }
1468         }
1469
1470         /*
1471          * Ok, we need to copy. Oh, well..
1472          */
1473         page_cache_get(old_page);
1474 gotten:
1475         pte_unmap_unlock(page_table, ptl);
1476
1477         if (unlikely(anon_vma_prepare(vma)))
1478                 goto oom;
1479         if (old_page == ZERO_PAGE(address)) {
1480                 new_page = alloc_zeroed_user_highpage(vma, address);
1481                 if (!new_page)
1482                         goto oom;
1483         } else {
1484                 new_page = alloc_page_vma(GFP_HIGHUSER, vma, address);
1485                 if (!new_page)
1486                         goto oom;
1487                 cow_user_page(new_page, old_page, address);
1488         }
1489
1490         /*
1491          * Re-check the pte - we dropped the lock
1492          */
1493         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1494         if (likely(pte_same(*page_table, orig_pte))) {
1495                 if (old_page) {
1496                         page_remove_rmap(old_page);
1497                         if (!PageAnon(old_page)) {
1498                                 dec_mm_counter(mm, file_rss);
1499                                 inc_mm_counter(mm, anon_rss);
1500                         }
1501                 } else
1502                         inc_mm_counter(mm, anon_rss);
1503                 flush_cache_page(vma, address, pte_pfn(orig_pte));
1504                 entry = mk_pte(new_page, vma->vm_page_prot);
1505                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1506                 ptep_establish(vma, address, page_table, entry);
1507                 update_mmu_cache(vma, address, entry);
1508                 lazy_mmu_prot_update(entry);
1509                 lru_cache_add_active(new_page);
1510                 page_add_new_anon_rmap(new_page, vma, address);
1511
1512                 /* Free the old page.. */
1513                 new_page = old_page;
1514                 ret |= VM_FAULT_WRITE;
1515         }
1516         if (new_page)
1517                 page_cache_release(new_page);
1518         if (old_page)
1519                 page_cache_release(old_page);
1520 unlock:
1521         pte_unmap_unlock(page_table, ptl);
1522         return ret;
1523 oom:
1524         if (old_page)
1525                 page_cache_release(old_page);
1526         return VM_FAULT_OOM;
1527 }
1528
1529 /*
1530  * Helper functions for unmap_mapping_range().
1531  *
1532  * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
1533  *
1534  * We have to restart searching the prio_tree whenever we drop the lock,
1535  * since the iterator is only valid while the lock is held, and anyway
1536  * a later vma might be split and reinserted earlier while lock dropped.
1537  *
1538  * The list of nonlinear vmas could be handled more efficiently, using
1539  * a placeholder, but handle it in the same way until a need is shown.
1540  * It is important to search the prio_tree before nonlinear list: a vma
1541  * may become nonlinear and be shifted from prio_tree to nonlinear list
1542  * while the lock is dropped; but never shifted from list to prio_tree.
1543  *
1544  * In order to make forward progress despite restarting the search,
1545  * vm_truncate_count is used to mark a vma as now dealt with, so we can
1546  * quickly skip it next time around.  Since the prio_tree search only
1547  * shows us those vmas affected by unmapping the range in question, we
1548  * can't efficiently keep all vmas in step with mapping->truncate_count:
1549  * so instead reset them all whenever it wraps back to 0 (then go to 1).
1550  * mapping->truncate_count and vma->vm_truncate_count are protected by
1551  * i_mmap_lock.
1552  *
1553  * In order to make forward progress despite repeatedly restarting some
1554  * large vma, note the restart_addr from unmap_vmas when it breaks out:
1555  * and restart from that address when we reach that vma again.  It might
1556  * have been split or merged, shrunk or extended, but never shifted: so
1557  * restart_addr remains valid so long as it remains in the vma's range.
1558  * unmap_mapping_range forces truncate_count to leap over page-aligned
1559  * values so we can save vma's restart_addr in its truncate_count field.
1560  */
1561 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
1562
1563 static void reset_vma_truncate_counts(struct address_space *mapping)
1564 {
1565         struct vm_area_struct *vma;
1566         struct prio_tree_iter iter;
1567
1568         vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
1569                 vma->vm_truncate_count = 0;
1570         list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
1571                 vma->vm_truncate_count = 0;
1572 }
1573
1574 static int unmap_mapping_range_vma(struct vm_area_struct *vma,
1575                 unsigned long start_addr, unsigned long end_addr,
1576                 struct zap_details *details)
1577 {
1578         unsigned long restart_addr;
1579         int need_break;
1580
1581 again:
1582         restart_addr = vma->vm_truncate_count;
1583         if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
1584                 start_addr = restart_addr;
1585                 if (start_addr >= end_addr) {
1586                         /* Top of vma has been split off since last time */
1587                         vma->vm_truncate_count = details->truncate_count;
1588                         return 0;
1589                 }
1590         }
1591
1592         restart_addr = zap_page_range(vma, start_addr,
1593                                         end_addr - start_addr, details);
1594         need_break = need_resched() ||
1595                         need_lockbreak(details->i_mmap_lock);
1596
1597         if (restart_addr >= end_addr) {
1598                 /* We have now completed this vma: mark it so */
1599                 vma->vm_truncate_count = details->truncate_count;
1600                 if (!need_break)
1601                         return 0;
1602         } else {
1603                 /* Note restart_addr in vma's truncate_count field */
1604                 vma->vm_truncate_count = restart_addr;
1605                 if (!need_break)
1606                         goto again;
1607         }
1608
1609         spin_unlock(details->i_mmap_lock);
1610         cond_resched();
1611         spin_lock(details->i_mmap_lock);
1612         return -EINTR;
1613 }
1614
1615 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
1616                                             struct zap_details *details)
1617 {
1618         struct vm_area_struct *vma;
1619         struct prio_tree_iter iter;
1620         pgoff_t vba, vea, zba, zea;
1621
1622 restart:
1623         vma_prio_tree_foreach(vma, &iter, root,
1624                         details->first_index, details->last_index) {
1625                 /* Skip quickly over those we have already dealt with */
1626                 if (vma->vm_truncate_count == details->truncate_count)
1627                         continue;
1628
1629                 vba = vma->vm_pgoff;
1630                 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
1631                 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
1632                 zba = details->first_index;
1633                 if (zba < vba)
1634                         zba = vba;
1635                 zea = details->last_index;
1636                 if (zea > vea)
1637                         zea = vea;
1638
1639                 if (unmap_mapping_range_vma(vma,
1640                         ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
1641                         ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
1642                                 details) < 0)
1643                         goto restart;
1644         }
1645 }
1646
1647 static inline void unmap_mapping_range_list(struct list_head *head,
1648                                             struct zap_details *details)
1649 {
1650         struct vm_area_struct *vma;
1651
1652         /*
1653          * In nonlinear VMAs there is no correspondence between virtual address
1654          * offset and file offset.  So we must perform an exhaustive search
1655          * across *all* the pages in each nonlinear VMA, not just the pages
1656          * whose virtual address lies outside the file truncation point.
1657          */
1658 restart:
1659         list_for_each_entry(vma, head, shared.vm_set.list) {
1660                 /* Skip quickly over those we have already dealt with */
1661                 if (vma->vm_truncate_count == details->truncate_count)
1662                         continue;
1663                 details->nonlinear_vma = vma;
1664                 if (unmap_mapping_range_vma(vma, vma->vm_start,
1665                                         vma->vm_end, details) < 0)
1666                         goto restart;
1667         }
1668 }
1669
1670 /**
1671  * unmap_mapping_range - unmap the portion of all mmaps
1672  * in the specified address_space corresponding to the specified
1673  * page range in the underlying file.
1674  * @mapping: the address space containing mmaps to be unmapped.
1675  * @holebegin: byte in first page to unmap, relative to the start of
1676  * the underlying file.  This will be rounded down to a PAGE_SIZE
1677  * boundary.  Note that this is different from vmtruncate(), which
1678  * must keep the partial page.  In contrast, we must get rid of
1679  * partial pages.
1680  * @holelen: size of prospective hole in bytes.  This will be rounded
1681  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
1682  * end of the file.
1683  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
1684  * but 0 when invalidating pagecache, don't throw away private data.
1685  */
1686 void unmap_mapping_range(struct address_space *mapping,
1687                 loff_t const holebegin, loff_t const holelen, int even_cows)
1688 {
1689         struct zap_details details;
1690         pgoff_t hba = holebegin >> PAGE_SHIFT;
1691         pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1692
1693         /* Check for overflow. */
1694         if (sizeof(holelen) > sizeof(hlen)) {
1695                 long long holeend =
1696                         (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1697                 if (holeend & ~(long long)ULONG_MAX)
1698                         hlen = ULONG_MAX - hba + 1;
1699         }
1700
1701         details.check_mapping = even_cows? NULL: mapping;
1702         details.nonlinear_vma = NULL;
1703         details.first_index = hba;
1704         details.last_index = hba + hlen - 1;
1705         if (details.last_index < details.first_index)
1706                 details.last_index = ULONG_MAX;
1707         details.i_mmap_lock = &mapping->i_mmap_lock;
1708
1709         spin_lock(&mapping->i_mmap_lock);
1710
1711         /* serialize i_size write against truncate_count write */
1712         smp_wmb();
1713         /* Protect against page faults, and endless unmapping loops */
1714         mapping->truncate_count++;
1715         /*
1716          * For archs where spin_lock has inclusive semantics like ia64
1717          * this smp_mb() will prevent to read pagetable contents
1718          * before the truncate_count increment is visible to
1719          * other cpus.
1720          */
1721         smp_mb();
1722         if (unlikely(is_restart_addr(mapping->truncate_count))) {
1723                 if (mapping->truncate_count == 0)
1724                         reset_vma_truncate_counts(mapping);
1725                 mapping->truncate_count++;
1726         }
1727         details.truncate_count = mapping->truncate_count;
1728
1729         if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
1730                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
1731         if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
1732                 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
1733         spin_unlock(&mapping->i_mmap_lock);
1734 }
1735 EXPORT_SYMBOL(unmap_mapping_range);
1736
1737 /*
1738  * Handle all mappings that got truncated by a "truncate()"
1739  * system call.
1740  *
1741  * NOTE! We have to be ready to update the memory sharing
1742  * between the file and the memory map for a potential last
1743  * incomplete page.  Ugly, but necessary.
1744  */
1745 int vmtruncate(struct inode * inode, loff_t offset)
1746 {
1747         struct address_space *mapping = inode->i_mapping;
1748         unsigned long limit;
1749
1750         if (inode->i_size < offset)
1751                 goto do_expand;
1752         /*
1753          * truncation of in-use swapfiles is disallowed - it would cause
1754          * subsequent swapout to scribble on the now-freed blocks.
1755          */
1756         if (IS_SWAPFILE(inode))
1757                 goto out_busy;
1758         i_size_write(inode, offset);
1759         unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
1760         truncate_inode_pages(mapping, offset);
1761         goto out_truncate;
1762
1763 do_expand:
1764         limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1765         if (limit != RLIM_INFINITY && offset > limit)
1766                 goto out_sig;
1767         if (offset > inode->i_sb->s_maxbytes)
1768                 goto out_big;
1769         i_size_write(inode, offset);
1770
1771 out_truncate:
1772         if (inode->i_op && inode->i_op->truncate)
1773                 inode->i_op->truncate(inode);
1774         return 0;
1775 out_sig:
1776         send_sig(SIGXFSZ, current, 0);
1777 out_big:
1778         return -EFBIG;
1779 out_busy:
1780         return -ETXTBSY;
1781 }
1782 EXPORT_SYMBOL(vmtruncate);
1783
1784 int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
1785 {
1786         struct address_space *mapping = inode->i_mapping;
1787
1788         /*
1789          * If the underlying filesystem is not going to provide
1790          * a way to truncate a range of blocks (punch a hole) -
1791          * we should return failure right now.
1792          */
1793         if (!inode->i_op || !inode->i_op->truncate_range)
1794                 return -ENOSYS;
1795
1796         mutex_lock(&inode->i_mutex);
1797         down_write(&inode->i_alloc_sem);
1798         unmap_mapping_range(mapping, offset, (end - offset), 1);
1799         truncate_inode_pages_range(mapping, offset, end);
1800         inode->i_op->truncate_range(inode, offset, end);
1801         up_write(&inode->i_alloc_sem);
1802         mutex_unlock(&inode->i_mutex);
1803
1804         return 0;
1805 }
1806 EXPORT_SYMBOL(vmtruncate_range);
1807
1808 /* 
1809  * Primitive swap readahead code. We simply read an aligned block of
1810  * (1 << page_cluster) entries in the swap area. This method is chosen
1811  * because it doesn't cost us any seek time.  We also make sure to queue
1812  * the 'original' request together with the readahead ones...  
1813  *
1814  * This has been extended to use the NUMA policies from the mm triggering
1815  * the readahead.
1816  *
1817  * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
1818  */
1819 void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma)
1820 {
1821 #ifdef CONFIG_NUMA
1822         struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL;
1823 #endif
1824         int i, num;
1825         struct page *new_page;
1826         unsigned long offset;
1827
1828         /*
1829          * Get the number of handles we should do readahead io to.
1830          */
1831         num = valid_swaphandles(entry, &offset);
1832         for (i = 0; i < num; offset++, i++) {
1833                 /* Ok, do the async read-ahead now */
1834                 new_page = read_swap_cache_async(swp_entry(swp_type(entry),
1835                                                            offset), vma, addr);
1836                 if (!new_page)
1837                         break;
1838                 page_cache_release(new_page);
1839 #ifdef CONFIG_NUMA
1840                 /*
1841                  * Find the next applicable VMA for the NUMA policy.
1842                  */
1843                 addr += PAGE_SIZE;
1844                 if (addr == 0)
1845                         vma = NULL;
1846                 if (vma) {
1847                         if (addr >= vma->vm_end) {
1848                                 vma = next_vma;
1849                                 next_vma = vma ? vma->vm_next : NULL;
1850                         }
1851                         if (vma && addr < vma->vm_start)
1852                                 vma = NULL;
1853                 } else {
1854                         if (next_vma && addr >= next_vma->vm_start) {
1855                                 vma = next_vma;
1856                                 next_vma = vma->vm_next;
1857                         }
1858                 }
1859 #endif
1860         }
1861         lru_add_drain();        /* Push any new pages onto the LRU now */
1862 }
1863
1864 /*
1865  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1866  * but allow concurrent faults), and pte mapped but not yet locked.
1867  * We return with mmap_sem still held, but pte unmapped and unlocked.
1868  */
1869 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
1870                 unsigned long address, pte_t *page_table, pmd_t *pmd,
1871                 int write_access, pte_t orig_pte)
1872 {
1873         spinlock_t *ptl;
1874         struct page *page;
1875         swp_entry_t entry;
1876         pte_t pte;
1877         int ret = VM_FAULT_MINOR;
1878
1879         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
1880                 goto out;
1881
1882         entry = pte_to_swp_entry(orig_pte);
1883 again:
1884         page = lookup_swap_cache(entry);
1885         if (!page) {
1886                 swapin_readahead(entry, address, vma);
1887                 page = read_swap_cache_async(entry, vma, address);
1888                 if (!page) {
1889                         /*
1890                          * Back out if somebody else faulted in this pte
1891                          * while we released the pte lock.
1892                          */
1893                         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1894                         if (likely(pte_same(*page_table, orig_pte)))
1895                                 ret = VM_FAULT_OOM;
1896                         goto unlock;
1897                 }
1898
1899                 /* Had to read the page from swap area: Major fault */
1900                 ret = VM_FAULT_MAJOR;
1901                 inc_page_state(pgmajfault);
1902                 grab_swap_token();
1903         }
1904
1905         mark_page_accessed(page);
1906         lock_page(page);
1907         if (!PageSwapCache(page)) {
1908                 /* Page migration has occured */
1909                 unlock_page(page);
1910                 page_cache_release(page);
1911                 goto again;
1912         }
1913
1914         /*
1915          * Back out if somebody else already faulted in this pte.
1916          */
1917         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1918         if (unlikely(!pte_same(*page_table, orig_pte)))
1919                 goto out_nomap;
1920
1921         if (unlikely(!PageUptodate(page))) {
1922                 ret = VM_FAULT_SIGBUS;
1923                 goto out_nomap;
1924         }
1925
1926         /* The page isn't present yet, go ahead with the fault. */
1927
1928         inc_mm_counter(mm, anon_rss);
1929         pte = mk_pte(page, vma->vm_page_prot);
1930         if (write_access && can_share_swap_page(page)) {
1931                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
1932                 write_access = 0;
1933         }
1934
1935         flush_icache_page(vma, page);
1936         set_pte_at(mm, address, page_table, pte);
1937         page_add_anon_rmap(page, vma, address);
1938
1939         swap_free(entry);
1940         if (vm_swap_full())
1941                 remove_exclusive_swap_page(page);
1942         unlock_page(page);
1943
1944         if (write_access) {
1945                 if (do_wp_page(mm, vma, address,
1946                                 page_table, pmd, ptl, pte) == VM_FAULT_OOM)
1947                         ret = VM_FAULT_OOM;
1948                 goto out;
1949         }
1950
1951         /* No need to invalidate - it was non-present before */
1952         update_mmu_cache(vma, address, pte);
1953         lazy_mmu_prot_update(pte);
1954 unlock:
1955         pte_unmap_unlock(page_table, ptl);
1956 out:
1957         return ret;
1958 out_nomap:
1959         pte_unmap_unlock(page_table, ptl);
1960         unlock_page(page);
1961         page_cache_release(page);
1962         return ret;
1963 }
1964
1965 /*
1966  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1967  * but allow concurrent faults), and pte mapped but not yet locked.
1968  * We return with mmap_sem still held, but pte unmapped and unlocked.
1969  */
1970 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
1971                 unsigned long address, pte_t *page_table, pmd_t *pmd,
1972                 int write_access)
1973 {
1974         struct page *page;
1975         spinlock_t *ptl;
1976         pte_t entry;
1977
1978         if (write_access) {
1979                 /* Allocate our own private page. */
1980                 pte_unmap(page_table);
1981
1982                 if (unlikely(anon_vma_prepare(vma)))
1983                         goto oom;
1984                 page = alloc_zeroed_user_highpage(vma, address);
1985                 if (!page)
1986                         goto oom;
1987
1988                 entry = mk_pte(page, vma->vm_page_prot);
1989                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1990
1991                 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1992                 if (!pte_none(*page_table))
1993                         goto release;
1994                 inc_mm_counter(mm, anon_rss);
1995                 lru_cache_add_active(page);
1996                 page_add_new_anon_rmap(page, vma, address);
1997         } else {
1998                 /* Map the ZERO_PAGE - vm_page_prot is readonly */
1999                 page = ZERO_PAGE(address);
2000                 page_cache_get(page);
2001                 entry = mk_pte(page, vma->vm_page_prot);
2002
2003                 ptl = pte_lockptr(mm, pmd);
2004                 spin_lock(ptl);
2005                 if (!pte_none(*page_table))
2006                         goto release;
2007                 inc_mm_counter(mm, file_rss);
2008                 page_add_file_rmap(page);
2009         }
2010
2011         set_pte_at(mm, address, page_table, entry);
2012
2013         /* No need to invalidate - it was non-present before */
2014         update_mmu_cache(vma, address, entry);
2015         lazy_mmu_prot_update(entry);
2016 unlock:
2017         pte_unmap_unlock(page_table, ptl);
2018         return VM_FAULT_MINOR;
2019 release:
2020         page_cache_release(page);
2021         goto unlock;
2022 oom:
2023         return VM_FAULT_OOM;
2024 }
2025
2026 /*
2027  * do_no_page() tries to create a new page mapping. It aggressively
2028  * tries to share with existing pages, but makes a separate copy if
2029  * the "write_access" parameter is true in order to avoid the next
2030  * page fault.
2031  *
2032  * As this is called only for pages that do not currently exist, we
2033  * do not need to flush old virtual caches or the TLB.
2034  *
2035  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2036  * but allow concurrent faults), and pte mapped but not yet locked.
2037  * We return with mmap_sem still held, but pte unmapped and unlocked.
2038  */
2039 static int do_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
2040                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2041                 int write_access)
2042 {
2043         spinlock_t *ptl;
2044         struct page *new_page;
2045         struct address_space *mapping = NULL;
2046         pte_t entry;
2047         unsigned int sequence = 0;
2048         int ret = VM_FAULT_MINOR;
2049         int anon = 0;
2050
2051         pte_unmap(page_table);
2052         BUG_ON(vma->vm_flags & VM_PFNMAP);
2053
2054         if (vma->vm_file) {
2055                 mapping = vma->vm_file->f_mapping;
2056                 sequence = mapping->truncate_count;
2057                 smp_rmb(); /* serializes i_size against truncate_count */
2058         }
2059 retry:
2060         new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
2061         /*
2062          * No smp_rmb is needed here as long as there's a full
2063          * spin_lock/unlock sequence inside the ->nopage callback
2064          * (for the pagecache lookup) that acts as an implicit
2065          * smp_mb() and prevents the i_size read to happen
2066          * after the next truncate_count read.
2067          */
2068
2069         /* no page was available -- either SIGBUS or OOM */
2070         if (new_page == NOPAGE_SIGBUS)
2071                 return VM_FAULT_SIGBUS;
2072         if (new_page == NOPAGE_OOM)
2073                 return VM_FAULT_OOM;
2074
2075         /*
2076          * Should we do an early C-O-W break?
2077          */
2078         if (write_access && !(vma->vm_flags & VM_SHARED)) {
2079                 struct page *page;
2080
2081                 if (unlikely(anon_vma_prepare(vma)))
2082                         goto oom;
2083                 page = alloc_page_vma(GFP_HIGHUSER, vma, address);
2084                 if (!page)
2085                         goto oom;
2086                 copy_user_highpage(page, new_page, address);
2087                 page_cache_release(new_page);
2088                 new_page = page;
2089                 anon = 1;
2090         }
2091
2092         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2093         /*
2094          * For a file-backed vma, someone could have truncated or otherwise
2095          * invalidated this page.  If unmap_mapping_range got called,
2096          * retry getting the page.
2097          */
2098         if (mapping && unlikely(sequence != mapping->truncate_count)) {
2099                 pte_unmap_unlock(page_table, ptl);
2100                 page_cache_release(new_page);
2101                 cond_resched();
2102                 sequence = mapping->truncate_count;
2103                 smp_rmb();
2104                 goto retry;
2105         }
2106
2107         /*
2108          * This silly early PAGE_DIRTY setting removes a race
2109          * due to the bad i386 page protection. But it's valid
2110          * for other architectures too.
2111          *
2112          * Note that if write_access is true, we either now have
2113          * an exclusive copy of the page, or this is a shared mapping,
2114          * so we can make it writable and dirty to avoid having to
2115          * handle that later.
2116          */
2117         /* Only go through if we didn't race with anybody else... */
2118         if (pte_none(*page_table)) {
2119                 flush_icache_page(vma, new_page);
2120                 entry = mk_pte(new_page, vma->vm_page_prot);
2121                 if (write_access)
2122                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2123                 set_pte_at(mm, address, page_table, entry);
2124                 if (anon) {
2125                         inc_mm_counter(mm, anon_rss);
2126                         lru_cache_add_active(new_page);
2127                         page_add_new_anon_rmap(new_page, vma, address);
2128                 } else {
2129                         inc_mm_counter(mm, file_rss);
2130                         page_add_file_rmap(new_page);
2131                 }
2132         } else {
2133                 /* One of our sibling threads was faster, back out. */
2134                 page_cache_release(new_page);
2135                 goto unlock;
2136         }
2137
2138         /* no need to invalidate: a not-present page shouldn't be cached */
2139         update_mmu_cache(vma, address, entry);
2140         lazy_mmu_prot_update(entry);
2141 unlock:
2142         pte_unmap_unlock(page_table, ptl);
2143         return ret;
2144 oom:
2145         page_cache_release(new_page);
2146         return VM_FAULT_OOM;
2147 }
2148
2149 /*
2150  * Fault of a previously existing named mapping. Repopulate the pte
2151  * from the encoded file_pte if possible. This enables swappable
2152  * nonlinear vmas.
2153  *
2154  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2155  * but allow concurrent faults), and pte mapped but not yet locked.
2156  * We return with mmap_sem still held, but pte unmapped and unlocked.
2157  */
2158 static int do_file_page(struct mm_struct *mm, struct vm_area_struct *vma,
2159                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2160                 int write_access, pte_t orig_pte)
2161 {
2162         pgoff_t pgoff;
2163         int err;
2164
2165         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2166                 return VM_FAULT_MINOR;
2167
2168         if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
2169                 /*
2170                  * Page table corrupted: show pte and kill process.
2171                  */
2172                 print_bad_pte(vma, orig_pte, address);
2173                 return VM_FAULT_OOM;
2174         }
2175         /* We can then assume vm->vm_ops && vma->vm_ops->populate */
2176
2177         pgoff = pte_to_pgoff(orig_pte);
2178         err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE,
2179                                         vma->vm_page_prot, pgoff, 0);
2180         if (err == -ENOMEM)
2181                 return VM_FAULT_OOM;
2182         if (err)
2183                 return VM_FAULT_SIGBUS;
2184         return VM_FAULT_MAJOR;
2185 }
2186
2187 /*
2188  * These routines also need to handle stuff like marking pages dirty
2189  * and/or accessed for architectures that don't do it in hardware (most
2190  * RISC architectures).  The early dirtying is also good on the i386.
2191  *
2192  * There is also a hook called "update_mmu_cache()" that architectures
2193  * with external mmu caches can use to update those (ie the Sparc or
2194  * PowerPC hashed page tables that act as extended TLBs).
2195  *
2196  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2197  * but allow concurrent faults), and pte mapped but not yet locked.
2198  * We return with mmap_sem still held, but pte unmapped and unlocked.
2199  */
2200 static inline int handle_pte_fault(struct mm_struct *mm,
2201                 struct vm_area_struct *vma, unsigned long address,
2202                 pte_t *pte, pmd_t *pmd, int write_access)
2203 {
2204         pte_t entry;
2205         pte_t old_entry;
2206         spinlock_t *ptl;
2207
2208         old_entry = entry = *pte;
2209         if (!pte_present(entry)) {
2210                 if (pte_none(entry)) {
2211                         if (!vma->vm_ops || !vma->vm_ops->nopage)
2212                                 return do_anonymous_page(mm, vma, address,
2213                                         pte, pmd, write_access);
2214                         return do_no_page(mm, vma, address,
2215                                         pte, pmd, write_access);
2216                 }
2217                 if (pte_file(entry))
2218                         return do_file_page(mm, vma, address,
2219                                         pte, pmd, write_access, entry);
2220                 return do_swap_page(mm, vma, address,
2221                                         pte, pmd, write_access, entry);
2222         }
2223
2224         ptl = pte_lockptr(mm, pmd);
2225         spin_lock(ptl);
2226         if (unlikely(!pte_same(*pte, entry)))
2227                 goto unlock;
2228         if (write_access) {
2229                 if (!pte_write(entry))
2230                         return do_wp_page(mm, vma, address,
2231                                         pte, pmd, ptl, entry);
2232                 entry = pte_mkdirty(entry);
2233         }
2234         entry = pte_mkyoung(entry);
2235         if (!pte_same(old_entry, entry)) {
2236                 ptep_set_access_flags(vma, address, pte, entry, write_access);
2237                 update_mmu_cache(vma, address, entry);
2238                 lazy_mmu_prot_update(entry);
2239         } else {
2240                 /*
2241                  * This is needed only for protection faults but the arch code
2242                  * is not yet telling us if this is a protection fault or not.
2243                  * This still avoids useless tlb flushes for .text page faults
2244                  * with threads.
2245                  */
2246                 if (write_access)
2247                         flush_tlb_page(vma, address);
2248         }
2249 unlock:
2250         pte_unmap_unlock(pte, ptl);
2251         return VM_FAULT_MINOR;
2252 }
2253
2254 /*
2255  * By the time we get here, we already hold the mm semaphore
2256  */
2257 int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2258                 unsigned long address, int write_access)
2259 {
2260         pgd_t *pgd;
2261         pud_t *pud;
2262         pmd_t *pmd;
2263         pte_t *pte;
2264
2265         __set_current_state(TASK_RUNNING);
2266
2267         inc_page_state(pgfault);
2268
2269         if (unlikely(is_vm_hugetlb_page(vma)))
2270                 return hugetlb_fault(mm, vma, address, write_access);
2271
2272         pgd = pgd_offset(mm, address);
2273         pud = pud_alloc(mm, pgd, address);
2274         if (!pud)
2275                 return VM_FAULT_OOM;
2276         pmd = pmd_alloc(mm, pud, address);
2277         if (!pmd)
2278                 return VM_FAULT_OOM;
2279         pte = pte_alloc_map(mm, pmd, address);
2280         if (!pte)
2281                 return VM_FAULT_OOM;
2282
2283         return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
2284 }
2285
2286 EXPORT_SYMBOL_GPL(__handle_mm_fault);
2287
2288 #ifndef __PAGETABLE_PUD_FOLDED
2289 /*
2290  * Allocate page upper directory.
2291  * We've already handled the fast-path in-line.
2292  */
2293 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2294 {
2295         pud_t *new = pud_alloc_one(mm, address);
2296         if (!new)
2297                 return -ENOMEM;
2298
2299         spin_lock(&mm->page_table_lock);
2300         if (pgd_present(*pgd))          /* Another has populated it */
2301                 pud_free(new);
2302         else
2303                 pgd_populate(mm, pgd, new);
2304         spin_unlock(&mm->page_table_lock);
2305         return 0;
2306 }
2307 #else
2308 /* Workaround for gcc 2.96 */
2309 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2310 {
2311         return 0;
2312 }
2313 #endif /* __PAGETABLE_PUD_FOLDED */
2314
2315 #ifndef __PAGETABLE_PMD_FOLDED
2316 /*
2317  * Allocate page middle directory.
2318  * We've already handled the fast-path in-line.
2319  */
2320 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2321 {
2322         pmd_t *new = pmd_alloc_one(mm, address);
2323         if (!new)
2324                 return -ENOMEM;
2325
2326         spin_lock(&mm->page_table_lock);
2327 #ifndef __ARCH_HAS_4LEVEL_HACK
2328         if (pud_present(*pud))          /* Another has populated it */
2329                 pmd_free(new);
2330         else
2331                 pud_populate(mm, pud, new);
2332 #else
2333         if (pgd_present(*pud))          /* Another has populated it */
2334                 pmd_free(new);
2335         else
2336                 pgd_populate(mm, pud, new);
2337 #endif /* __ARCH_HAS_4LEVEL_HACK */
2338         spin_unlock(&mm->page_table_lock);
2339         return 0;
2340 }
2341 #else
2342 /* Workaround for gcc 2.96 */
2343 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2344 {
2345         return 0;
2346 }
2347 #endif /* __PAGETABLE_PMD_FOLDED */
2348
2349 int make_pages_present(unsigned long addr, unsigned long end)
2350 {
2351         int ret, len, write;
2352         struct vm_area_struct * vma;
2353
2354         vma = find_vma(current->mm, addr);
2355         if (!vma)
2356                 return -1;
2357         write = (vma->vm_flags & VM_WRITE) != 0;
2358         if (addr >= end)
2359                 BUG();
2360         if (end > vma->vm_end)
2361                 BUG();
2362         len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE;
2363         ret = get_user_pages(current, current->mm, addr,
2364                         len, write, 0, NULL, NULL);
2365         if (ret < 0)
2366                 return ret;
2367         return ret == len ? 0 : -1;
2368 }
2369
2370 /* 
2371  * Map a vmalloc()-space virtual address to the physical page.
2372  */
2373 struct page * vmalloc_to_page(void * vmalloc_addr)
2374 {
2375         unsigned long addr = (unsigned long) vmalloc_addr;
2376         struct page *page = NULL;
2377         pgd_t *pgd = pgd_offset_k(addr);
2378         pud_t *pud;
2379         pmd_t *pmd;
2380         pte_t *ptep, pte;
2381   
2382         if (!pgd_none(*pgd)) {
2383                 pud = pud_offset(pgd, addr);
2384                 if (!pud_none(*pud)) {
2385                         pmd = pmd_offset(pud, addr);
2386                         if (!pmd_none(*pmd)) {
2387                                 ptep = pte_offset_map(pmd, addr);
2388                                 pte = *ptep;
2389                                 if (pte_present(pte))
2390                                         page = pte_page(pte);
2391                                 pte_unmap(ptep);
2392                         }
2393                 }
2394         }
2395         return page;
2396 }
2397
2398 EXPORT_SYMBOL(vmalloc_to_page);
2399
2400 /*
2401  * Map a vmalloc()-space virtual address to the physical page frame number.
2402  */
2403 unsigned long vmalloc_to_pfn(void * vmalloc_addr)
2404 {
2405         return page_to_pfn(vmalloc_to_page(vmalloc_addr));
2406 }
2407
2408 EXPORT_SYMBOL(vmalloc_to_pfn);
2409
2410 #if !defined(__HAVE_ARCH_GATE_AREA)
2411
2412 #if defined(AT_SYSINFO_EHDR)
2413 static struct vm_area_struct gate_vma;
2414
2415 static int __init gate_vma_init(void)
2416 {
2417         gate_vma.vm_mm = NULL;
2418         gate_vma.vm_start = FIXADDR_USER_START;
2419         gate_vma.vm_end = FIXADDR_USER_END;
2420         gate_vma.vm_page_prot = PAGE_READONLY;
2421         gate_vma.vm_flags = 0;
2422         return 0;
2423 }
2424 __initcall(gate_vma_init);
2425 #endif
2426
2427 struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
2428 {
2429 #ifdef AT_SYSINFO_EHDR
2430         return &gate_vma;
2431 #else
2432         return NULL;
2433 #endif
2434 }
2435
2436 int in_gate_area_no_task(unsigned long addr)
2437 {
2438 #ifdef AT_SYSINFO_EHDR
2439         if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
2440                 return 1;
2441 #endif
2442         return 0;
2443 }
2444
2445 #endif  /* __HAVE_ARCH_GATE_AREA */