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1 /*
2 * mm/mmap.c
3 *
4 * Written by obz.
5 *
6 * Address space accounting code <alan@redhat.com>
7 */
8
9 #include <linux/slab.h>
10 #include <linux/backing-dev.h>
11 #include <linux/mm.h>
12 #include <linux/shm.h>
13 #include <linux/mman.h>
14 #include <linux/pagemap.h>
15 #include <linux/swap.h>
16 #include <linux/syscalls.h>
17 #include <linux/capability.h>
18 #include <linux/init.h>
19 #include <linux/file.h>
20 #include <linux/fs.h>
21 #include <linux/personality.h>
22 #include <linux/security.h>
23 #include <linux/hugetlb.h>
24 #include <linux/profile.h>
25 #include <linux/module.h>
26 #include <linux/mount.h>
27 #include <linux/mempolicy.h>
28 #include <linux/rmap.h>
29
30 #include <asm/uaccess.h>
31 #include <asm/cacheflush.h>
32 #include <asm/tlb.h>
33 #include <asm/mmu_context.h>
34
35 #ifndef arch_mmap_check
36 #define arch_mmap_check(addr, len, flags) (0)
37 #endif
38
39 #ifndef arch_rebalance_pgtables
40 #define arch_rebalance_pgtables(addr, len) (addr)
41 #endif
42
43 static void unmap_region(struct mm_struct *mm,
44 struct vm_area_struct *vma, struct vm_area_struct *prev,
45 unsigned long start, unsigned long end);
46
47 /*
48 * WARNING: the debugging will use recursive algorithms so never enable this
49 * unless you know what you are doing.
50 */
51 #undef DEBUG_MM_RB
52
53 /* description of effects of mapping type and prot in current implementation.
54 * this is due to the limited x86 page protection hardware. The expected
55 * behavior is in parens:
56 *
57 * map_type prot
58 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
59 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
60 * w: (no) no w: (no) no w: (yes) yes w: (no) no
61 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
62 *
63 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
64 * w: (no) no w: (no) no w: (copy) copy w: (no) no
65 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
66 *
67 */
68 pgprot_t protection_map[16] = {
69 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
70 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
71 };
72
73 pgprot_t vm_get_page_prot(unsigned long vm_flags)
74 {
75 return protection_map[vm_flags &
76 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)];
77 }
78 EXPORT_SYMBOL(vm_get_page_prot);
79
80 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
81 int sysctl_overcommit_ratio = 50; /* default is 50% */
82 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
83 atomic_t vm_committed_space = ATOMIC_INIT(0);
84
85 /*
86 * Check that a process has enough memory to allocate a new virtual
87 * mapping. 0 means there is enough memory for the allocation to
88 * succeed and -ENOMEM implies there is not.
89 *
90 * We currently support three overcommit policies, which are set via the
91 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
92 *
93 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
94 * Additional code 2002 Jul 20 by Robert Love.
95 *
96 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
97 *
98 * Note this is a helper function intended to be used by LSMs which
99 * wish to use this logic.
100 */
101 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
102 {
103 unsigned long free, allowed;
104
105 vm_acct_memory(pages);
106
107 /*
108 * Sometimes we want to use more memory than we have
109 */
110 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
111 return 0;
112
113 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
114 unsigned long n;
115
116 free = global_page_state(NR_FILE_PAGES);
117 free += nr_swap_pages;
118
119 /*
120 * Any slabs which are created with the
121 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
122 * which are reclaimable, under pressure. The dentry
123 * cache and most inode caches should fall into this
124 */
125 free += global_page_state(NR_SLAB_RECLAIMABLE);
126
127 /*
128 * Leave the last 3% for root
129 */
130 if (!cap_sys_admin)
131 free -= free / 32;
132
133 if (free > pages)
134 return 0;
135
136 /*
137 * nr_free_pages() is very expensive on large systems,
138 * only call if we're about to fail.
139 */
140 n = nr_free_pages();
141
142 /*
143 * Leave reserved pages. The pages are not for anonymous pages.
144 */
145 if (n <= totalreserve_pages)
146 goto error;
147 else
148 n -= totalreserve_pages;
149
150 /*
151 * Leave the last 3% for root
152 */
153 if (!cap_sys_admin)
154 n -= n / 32;
155 free += n;
156
157 if (free > pages)
158 return 0;
159
160 goto error;
161 }
162
163 allowed = (totalram_pages - hugetlb_total_pages())
164 * sysctl_overcommit_ratio / 100;
165 /*
166 * Leave the last 3% for root
167 */
168 if (!cap_sys_admin)
169 allowed -= allowed / 32;
170 allowed += total_swap_pages;
171
172 /* Don't let a single process grow too big:
173 leave 3% of the size of this process for other processes */
174 allowed -= mm->total_vm / 32;
175
176 /*
177 * cast `allowed' as a signed long because vm_committed_space
178 * sometimes has a negative value
179 */
180 if (atomic_read(&vm_committed_space) < (long)allowed)
181 return 0;
182 error:
183 vm_unacct_memory(pages);
184
185 return -ENOMEM;
186 }
187
188 /*
189 * Requires inode->i_mapping->i_mmap_lock
190 */
191 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
192 struct file *file, struct address_space *mapping)
193 {
194 if (vma->vm_flags & VM_DENYWRITE)
195 atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
196 if (vma->vm_flags & VM_SHARED)
197 mapping->i_mmap_writable--;
198
199 flush_dcache_mmap_lock(mapping);
200 if (unlikely(vma->vm_flags & VM_NONLINEAR))
201 list_del_init(&vma->shared.vm_set.list);
202 else
203 vma_prio_tree_remove(vma, &mapping->i_mmap);
204 flush_dcache_mmap_unlock(mapping);
205 }
206
207 /*
208 * Unlink a file-based vm structure from its prio_tree, to hide
209 * vma from rmap and vmtruncate before freeing its page tables.
210 */
211 void unlink_file_vma(struct vm_area_struct *vma)
212 {
213 struct file *file = vma->vm_file;
214
215 if (file) {
216 struct address_space *mapping = file->f_mapping;
217 spin_lock(&mapping->i_mmap_lock);
218 __remove_shared_vm_struct(vma, file, mapping);
219 spin_unlock(&mapping->i_mmap_lock);
220 }
221 }
222
223 /*
224 * Close a vm structure and free it, returning the next.
225 */
226 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
227 {
228 struct vm_area_struct *next = vma->vm_next;
229
230 might_sleep();
231 if (vma->vm_ops && vma->vm_ops->close)
232 vma->vm_ops->close(vma);
233 if (vma->vm_file)
234 fput(vma->vm_file);
235 mpol_free(vma_policy(vma));
236 kmem_cache_free(vm_area_cachep, vma);
237 return next;
238 }
239
240 asmlinkage unsigned long sys_brk(unsigned long brk)
241 {
242 unsigned long rlim, retval;
243 unsigned long newbrk, oldbrk;
244 struct mm_struct *mm = current->mm;
245
246 down_write(&mm->mmap_sem);
247
248 if (brk < mm->start_brk)
249 goto out;
250
251 /*
252 * Check against rlimit here. If this check is done later after the test
253 * of oldbrk with newbrk then it can escape the test and let the data
254 * segment grow beyond its set limit the in case where the limit is
255 * not page aligned -Ram Gupta
256 */
257 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
258 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
259 (mm->end_data - mm->start_data) > rlim)
260 goto out;
261
262 newbrk = PAGE_ALIGN(brk);
263 oldbrk = PAGE_ALIGN(mm->brk);
264 if (oldbrk == newbrk)
265 goto set_brk;
266
267 /* Always allow shrinking brk. */
268 if (brk <= mm->brk) {
269 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
270 goto set_brk;
271 goto out;
272 }
273
274 /* Check against existing mmap mappings. */
275 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
276 goto out;
277
278 /* Ok, looks good - let it rip. */
279 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
280 goto out;
281 set_brk:
282 mm->brk = brk;
283 out:
284 retval = mm->brk;
285 up_write(&mm->mmap_sem);
286 return retval;
287 }
288
289 #ifdef DEBUG_MM_RB
290 static int browse_rb(struct rb_root *root)
291 {
292 int i = 0, j;
293 struct rb_node *nd, *pn = NULL;
294 unsigned long prev = 0, pend = 0;
295
296 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
297 struct vm_area_struct *vma;
298 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
299 if (vma->vm_start < prev)
300 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
301 if (vma->vm_start < pend)
302 printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
303 if (vma->vm_start > vma->vm_end)
304 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
305 i++;
306 pn = nd;
307 prev = vma->vm_start;
308 pend = vma->vm_end;
309 }
310 j = 0;
311 for (nd = pn; nd; nd = rb_prev(nd)) {
312 j++;
313 }
314 if (i != j)
315 printk("backwards %d, forwards %d\n", j, i), i = 0;
316 return i;
317 }
318
319 void validate_mm(struct mm_struct *mm)
320 {
321 int bug = 0;
322 int i = 0;
323 struct vm_area_struct *tmp = mm->mmap;
324 while (tmp) {
325 tmp = tmp->vm_next;
326 i++;
327 }
328 if (i != mm->map_count)
329 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
330 i = browse_rb(&mm->mm_rb);
331 if (i != mm->map_count)
332 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
333 BUG_ON(bug);
334 }
335 #else
336 #define validate_mm(mm) do { } while (0)
337 #endif
338
339 static struct vm_area_struct *
340 find_vma_prepare(struct mm_struct *mm, unsigned long addr,
341 struct vm_area_struct **pprev, struct rb_node ***rb_link,
342 struct rb_node ** rb_parent)
343 {
344 struct vm_area_struct * vma;
345 struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
346
347 __rb_link = &mm->mm_rb.rb_node;
348 rb_prev = __rb_parent = NULL;
349 vma = NULL;
350
351 while (*__rb_link) {
352 struct vm_area_struct *vma_tmp;
353
354 __rb_parent = *__rb_link;
355 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
356
357 if (vma_tmp->vm_end > addr) {
358 vma = vma_tmp;
359 if (vma_tmp->vm_start <= addr)
360 return vma;
361 __rb_link = &__rb_parent->rb_left;
362 } else {
363 rb_prev = __rb_parent;
364 __rb_link = &__rb_parent->rb_right;
365 }
366 }
367
368 *pprev = NULL;
369 if (rb_prev)
370 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
371 *rb_link = __rb_link;
372 *rb_parent = __rb_parent;
373 return vma;
374 }
375
376 static inline void
377 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
378 struct vm_area_struct *prev, struct rb_node *rb_parent)
379 {
380 if (prev) {
381 vma->vm_next = prev->vm_next;
382 prev->vm_next = vma;
383 } else {
384 mm->mmap = vma;
385 if (rb_parent)
386 vma->vm_next = rb_entry(rb_parent,
387 struct vm_area_struct, vm_rb);
388 else
389 vma->vm_next = NULL;
390 }
391 }
392
393 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
394 struct rb_node **rb_link, struct rb_node *rb_parent)
395 {
396 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
397 rb_insert_color(&vma->vm_rb, &mm->mm_rb);
398 }
399
400 static inline void __vma_link_file(struct vm_area_struct *vma)
401 {
402 struct file * file;
403
404 file = vma->vm_file;
405 if (file) {
406 struct address_space *mapping = file->f_mapping;
407
408 if (vma->vm_flags & VM_DENYWRITE)
409 atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
410 if (vma->vm_flags & VM_SHARED)
411 mapping->i_mmap_writable++;
412
413 flush_dcache_mmap_lock(mapping);
414 if (unlikely(vma->vm_flags & VM_NONLINEAR))
415 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
416 else
417 vma_prio_tree_insert(vma, &mapping->i_mmap);
418 flush_dcache_mmap_unlock(mapping);
419 }
420 }
421
422 static void
423 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
424 struct vm_area_struct *prev, struct rb_node **rb_link,
425 struct rb_node *rb_parent)
426 {
427 __vma_link_list(mm, vma, prev, rb_parent);
428 __vma_link_rb(mm, vma, rb_link, rb_parent);
429 __anon_vma_link(vma);
430 }
431
432 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
433 struct vm_area_struct *prev, struct rb_node **rb_link,
434 struct rb_node *rb_parent)
435 {
436 struct address_space *mapping = NULL;
437
438 if (vma->vm_file)
439 mapping = vma->vm_file->f_mapping;
440
441 if (mapping) {
442 spin_lock(&mapping->i_mmap_lock);
443 vma->vm_truncate_count = mapping->truncate_count;
444 }
445 anon_vma_lock(vma);
446
447 __vma_link(mm, vma, prev, rb_link, rb_parent);
448 __vma_link_file(vma);
449
450 anon_vma_unlock(vma);
451 if (mapping)
452 spin_unlock(&mapping->i_mmap_lock);
453
454 mm->map_count++;
455 validate_mm(mm);
456 }
457
458 /*
459 * Helper for vma_adjust in the split_vma insert case:
460 * insert vm structure into list and rbtree and anon_vma,
461 * but it has already been inserted into prio_tree earlier.
462 */
463 static void
464 __insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
465 {
466 struct vm_area_struct * __vma, * prev;
467 struct rb_node ** rb_link, * rb_parent;
468
469 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
470 BUG_ON(__vma && __vma->vm_start < vma->vm_end);
471 __vma_link(mm, vma, prev, rb_link, rb_parent);
472 mm->map_count++;
473 }
474
475 static inline void
476 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
477 struct vm_area_struct *prev)
478 {
479 prev->vm_next = vma->vm_next;
480 rb_erase(&vma->vm_rb, &mm->mm_rb);
481 if (mm->mmap_cache == vma)
482 mm->mmap_cache = prev;
483 }
484
485 /*
486 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
487 * is already present in an i_mmap tree without adjusting the tree.
488 * The following helper function should be used when such adjustments
489 * are necessary. The "insert" vma (if any) is to be inserted
490 * before we drop the necessary locks.
491 */
492 void vma_adjust(struct vm_area_struct *vma, unsigned long start,
493 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
494 {
495 struct mm_struct *mm = vma->vm_mm;
496 struct vm_area_struct *next = vma->vm_next;
497 struct vm_area_struct *importer = NULL;
498 struct address_space *mapping = NULL;
499 struct prio_tree_root *root = NULL;
500 struct file *file = vma->vm_file;
501 struct anon_vma *anon_vma = NULL;
502 long adjust_next = 0;
503 int remove_next = 0;
504
505 if (next && !insert) {
506 if (end >= next->vm_end) {
507 /*
508 * vma expands, overlapping all the next, and
509 * perhaps the one after too (mprotect case 6).
510 */
511 again: remove_next = 1 + (end > next->vm_end);
512 end = next->vm_end;
513 anon_vma = next->anon_vma;
514 importer = vma;
515 } else if (end > next->vm_start) {
516 /*
517 * vma expands, overlapping part of the next:
518 * mprotect case 5 shifting the boundary up.
519 */
520 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
521 anon_vma = next->anon_vma;
522 importer = vma;
523 } else if (end < vma->vm_end) {
524 /*
525 * vma shrinks, and !insert tells it's not
526 * split_vma inserting another: so it must be
527 * mprotect case 4 shifting the boundary down.
528 */
529 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
530 anon_vma = next->anon_vma;
531 importer = next;
532 }
533 }
534
535 if (file) {
536 mapping = file->f_mapping;
537 if (!(vma->vm_flags & VM_NONLINEAR))
538 root = &mapping->i_mmap;
539 spin_lock(&mapping->i_mmap_lock);
540 if (importer &&
541 vma->vm_truncate_count != next->vm_truncate_count) {
542 /*
543 * unmap_mapping_range might be in progress:
544 * ensure that the expanding vma is rescanned.
545 */
546 importer->vm_truncate_count = 0;
547 }
548 if (insert) {
549 insert->vm_truncate_count = vma->vm_truncate_count;
550 /*
551 * Put into prio_tree now, so instantiated pages
552 * are visible to arm/parisc __flush_dcache_page
553 * throughout; but we cannot insert into address
554 * space until vma start or end is updated.
555 */
556 __vma_link_file(insert);
557 }
558 }
559
560 /*
561 * When changing only vma->vm_end, we don't really need
562 * anon_vma lock: but is that case worth optimizing out?
563 */
564 if (vma->anon_vma)
565 anon_vma = vma->anon_vma;
566 if (anon_vma) {
567 spin_lock(&anon_vma->lock);
568 /*
569 * Easily overlooked: when mprotect shifts the boundary,
570 * make sure the expanding vma has anon_vma set if the
571 * shrinking vma had, to cover any anon pages imported.
572 */
573 if (importer && !importer->anon_vma) {
574 importer->anon_vma = anon_vma;
575 __anon_vma_link(importer);
576 }
577 }
578
579 if (root) {
580 flush_dcache_mmap_lock(mapping);
581 vma_prio_tree_remove(vma, root);
582 if (adjust_next)
583 vma_prio_tree_remove(next, root);
584 }
585
586 vma->vm_start = start;
587 vma->vm_end = end;
588 vma->vm_pgoff = pgoff;
589 if (adjust_next) {
590 next->vm_start += adjust_next << PAGE_SHIFT;
591 next->vm_pgoff += adjust_next;
592 }
593
594 if (root) {
595 if (adjust_next)
596 vma_prio_tree_insert(next, root);
597 vma_prio_tree_insert(vma, root);
598 flush_dcache_mmap_unlock(mapping);
599 }
600
601 if (remove_next) {
602 /*
603 * vma_merge has merged next into vma, and needs
604 * us to remove next before dropping the locks.
605 */
606 __vma_unlink(mm, next, vma);
607 if (file)
608 __remove_shared_vm_struct(next, file, mapping);
609 if (next->anon_vma)
610 __anon_vma_merge(vma, next);
611 } else if (insert) {
612 /*
613 * split_vma has split insert from vma, and needs
614 * us to insert it before dropping the locks
615 * (it may either follow vma or precede it).
616 */
617 __insert_vm_struct(mm, insert);
618 }
619
620 if (anon_vma)
621 spin_unlock(&anon_vma->lock);
622 if (mapping)
623 spin_unlock(&mapping->i_mmap_lock);
624
625 if (remove_next) {
626 if (file)
627 fput(file);
628 mm->map_count--;
629 mpol_free(vma_policy(next));
630 kmem_cache_free(vm_area_cachep, next);
631 /*
632 * In mprotect's case 6 (see comments on vma_merge),
633 * we must remove another next too. It would clutter
634 * up the code too much to do both in one go.
635 */
636 if (remove_next == 2) {
637 next = vma->vm_next;
638 goto again;
639 }
640 }
641
642 validate_mm(mm);
643 }
644
645 /*
646 * If the vma has a ->close operation then the driver probably needs to release
647 * per-vma resources, so we don't attempt to merge those.
648 */
649 #define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP)
650
651 static inline int is_mergeable_vma(struct vm_area_struct *vma,
652 struct file *file, unsigned long vm_flags)
653 {
654 if (vma->vm_flags != vm_flags)
655 return 0;
656 if (vma->vm_file != file)
657 return 0;
658 if (vma->vm_ops && vma->vm_ops->close)
659 return 0;
660 return 1;
661 }
662
663 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
664 struct anon_vma *anon_vma2)
665 {
666 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
667 }
668
669 /*
670 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
671 * in front of (at a lower virtual address and file offset than) the vma.
672 *
673 * We cannot merge two vmas if they have differently assigned (non-NULL)
674 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
675 *
676 * We don't check here for the merged mmap wrapping around the end of pagecache
677 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
678 * wrap, nor mmaps which cover the final page at index -1UL.
679 */
680 static int
681 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
682 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
683 {
684 if (is_mergeable_vma(vma, file, vm_flags) &&
685 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
686 if (vma->vm_pgoff == vm_pgoff)
687 return 1;
688 }
689 return 0;
690 }
691
692 /*
693 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
694 * beyond (at a higher virtual address and file offset than) the vma.
695 *
696 * We cannot merge two vmas if they have differently assigned (non-NULL)
697 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
698 */
699 static int
700 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
701 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
702 {
703 if (is_mergeable_vma(vma, file, vm_flags) &&
704 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
705 pgoff_t vm_pglen;
706 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
707 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
708 return 1;
709 }
710 return 0;
711 }
712
713 /*
714 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
715 * whether that can be merged with its predecessor or its successor.
716 * Or both (it neatly fills a hole).
717 *
718 * In most cases - when called for mmap, brk or mremap - [addr,end) is
719 * certain not to be mapped by the time vma_merge is called; but when
720 * called for mprotect, it is certain to be already mapped (either at
721 * an offset within prev, or at the start of next), and the flags of
722 * this area are about to be changed to vm_flags - and the no-change
723 * case has already been eliminated.
724 *
725 * The following mprotect cases have to be considered, where AAAA is
726 * the area passed down from mprotect_fixup, never extending beyond one
727 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
728 *
729 * AAAA AAAA AAAA AAAA
730 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
731 * cannot merge might become might become might become
732 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
733 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
734 * mremap move: PPPPNNNNNNNN 8
735 * AAAA
736 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
737 * might become case 1 below case 2 below case 3 below
738 *
739 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
740 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
741 */
742 struct vm_area_struct *vma_merge(struct mm_struct *mm,
743 struct vm_area_struct *prev, unsigned long addr,
744 unsigned long end, unsigned long vm_flags,
745 struct anon_vma *anon_vma, struct file *file,
746 pgoff_t pgoff, struct mempolicy *policy)
747 {
748 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
749 struct vm_area_struct *area, *next;
750
751 /*
752 * We later require that vma->vm_flags == vm_flags,
753 * so this tests vma->vm_flags & VM_SPECIAL, too.
754 */
755 if (vm_flags & VM_SPECIAL)
756 return NULL;
757
758 if (prev)
759 next = prev->vm_next;
760 else
761 next = mm->mmap;
762 area = next;
763 if (next && next->vm_end == end) /* cases 6, 7, 8 */
764 next = next->vm_next;
765
766 /*
767 * Can it merge with the predecessor?
768 */
769 if (prev && prev->vm_end == addr &&
770 mpol_equal(vma_policy(prev), policy) &&
771 can_vma_merge_after(prev, vm_flags,
772 anon_vma, file, pgoff)) {
773 /*
774 * OK, it can. Can we now merge in the successor as well?
775 */
776 if (next && end == next->vm_start &&
777 mpol_equal(policy, vma_policy(next)) &&
778 can_vma_merge_before(next, vm_flags,
779 anon_vma, file, pgoff+pglen) &&
780 is_mergeable_anon_vma(prev->anon_vma,
781 next->anon_vma)) {
782 /* cases 1, 6 */
783 vma_adjust(prev, prev->vm_start,
784 next->vm_end, prev->vm_pgoff, NULL);
785 } else /* cases 2, 5, 7 */
786 vma_adjust(prev, prev->vm_start,
787 end, prev->vm_pgoff, NULL);
788 return prev;
789 }
790
791 /*
792 * Can this new request be merged in front of next?
793 */
794 if (next && end == next->vm_start &&
795 mpol_equal(policy, vma_policy(next)) &&
796 can_vma_merge_before(next, vm_flags,
797 anon_vma, file, pgoff+pglen)) {
798 if (prev && addr < prev->vm_end) /* case 4 */
799 vma_adjust(prev, prev->vm_start,
800 addr, prev->vm_pgoff, NULL);
801 else /* cases 3, 8 */
802 vma_adjust(area, addr, next->vm_end,
803 next->vm_pgoff - pglen, NULL);
804 return area;
805 }
806
807 return NULL;
808 }
809
810 /*
811 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
812 * neighbouring vmas for a suitable anon_vma, before it goes off
813 * to allocate a new anon_vma. It checks because a repetitive
814 * sequence of mprotects and faults may otherwise lead to distinct
815 * anon_vmas being allocated, preventing vma merge in subsequent
816 * mprotect.
817 */
818 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
819 {
820 struct vm_area_struct *near;
821 unsigned long vm_flags;
822
823 near = vma->vm_next;
824 if (!near)
825 goto try_prev;
826
827 /*
828 * Since only mprotect tries to remerge vmas, match flags
829 * which might be mprotected into each other later on.
830 * Neither mlock nor madvise tries to remerge at present,
831 * so leave their flags as obstructing a merge.
832 */
833 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
834 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
835
836 if (near->anon_vma && vma->vm_end == near->vm_start &&
837 mpol_equal(vma_policy(vma), vma_policy(near)) &&
838 can_vma_merge_before(near, vm_flags,
839 NULL, vma->vm_file, vma->vm_pgoff +
840 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)))
841 return near->anon_vma;
842 try_prev:
843 /*
844 * It is potentially slow to have to call find_vma_prev here.
845 * But it's only on the first write fault on the vma, not
846 * every time, and we could devise a way to avoid it later
847 * (e.g. stash info in next's anon_vma_node when assigning
848 * an anon_vma, or when trying vma_merge). Another time.
849 */
850 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
851 if (!near)
852 goto none;
853
854 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
855 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
856
857 if (near->anon_vma && near->vm_end == vma->vm_start &&
858 mpol_equal(vma_policy(near), vma_policy(vma)) &&
859 can_vma_merge_after(near, vm_flags,
860 NULL, vma->vm_file, vma->vm_pgoff))
861 return near->anon_vma;
862 none:
863 /*
864 * There's no absolute need to look only at touching neighbours:
865 * we could search further afield for "compatible" anon_vmas.
866 * But it would probably just be a waste of time searching,
867 * or lead to too many vmas hanging off the same anon_vma.
868 * We're trying to allow mprotect remerging later on,
869 * not trying to minimize memory used for anon_vmas.
870 */
871 return NULL;
872 }
873
874 #ifdef CONFIG_PROC_FS
875 void vm_stat_account(struct mm_struct *mm, unsigned long flags,
876 struct file *file, long pages)
877 {
878 const unsigned long stack_flags
879 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
880
881 if (file) {
882 mm->shared_vm += pages;
883 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
884 mm->exec_vm += pages;
885 } else if (flags & stack_flags)
886 mm->stack_vm += pages;
887 if (flags & (VM_RESERVED|VM_IO))
888 mm->reserved_vm += pages;
889 }
890 #endif /* CONFIG_PROC_FS */
891
892 /*
893 * The caller must hold down_write(current->mm->mmap_sem).
894 */
895
896 unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
897 unsigned long len, unsigned long prot,
898 unsigned long flags, unsigned long pgoff)
899 {
900 struct mm_struct * mm = current->mm;
901 struct inode *inode;
902 unsigned int vm_flags;
903 int error;
904 int accountable = 1;
905 unsigned long reqprot = prot;
906
907 /*
908 * Does the application expect PROT_READ to imply PROT_EXEC?
909 *
910 * (the exception is when the underlying filesystem is noexec
911 * mounted, in which case we dont add PROT_EXEC.)
912 */
913 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
914 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
915 prot |= PROT_EXEC;
916
917 if (!len)
918 return -EINVAL;
919
920 if (!(flags & MAP_FIXED))
921 addr = round_hint_to_min(addr);
922
923 error = arch_mmap_check(addr, len, flags);
924 if (error)
925 return error;
926
927 /* Careful about overflows.. */
928 len = PAGE_ALIGN(len);
929 if (!len || len > TASK_SIZE)
930 return -ENOMEM;
931
932 /* offset overflow? */
933 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
934 return -EOVERFLOW;
935
936 /* Too many mappings? */
937 if (mm->map_count > sysctl_max_map_count)
938 return -ENOMEM;
939
940 /* Obtain the address to map to. we verify (or select) it and ensure
941 * that it represents a valid section of the address space.
942 */
943 addr = get_unmapped_area(file, addr, len, pgoff, flags);
944 if (addr & ~PAGE_MASK)
945 return addr;
946
947 /* Do simple checking here so the lower-level routines won't have
948 * to. we assume access permissions have been handled by the open
949 * of the memory object, so we don't do any here.
950 */
951 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
952 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
953
954 if (flags & MAP_LOCKED) {
955 if (!can_do_mlock())
956 return -EPERM;
957 vm_flags |= VM_LOCKED;
958 }
959 /* mlock MCL_FUTURE? */
960 if (vm_flags & VM_LOCKED) {
961 unsigned long locked, lock_limit;
962 locked = len >> PAGE_SHIFT;
963 locked += mm->locked_vm;
964 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
965 lock_limit >>= PAGE_SHIFT;
966 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
967 return -EAGAIN;
968 }
969
970 inode = file ? file->f_path.dentry->d_inode : NULL;
971
972 if (file) {
973 switch (flags & MAP_TYPE) {
974 case MAP_SHARED:
975 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
976 return -EACCES;
977
978 /*
979 * Make sure we don't allow writing to an append-only
980 * file..
981 */
982 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
983 return -EACCES;
984
985 /*
986 * Make sure there are no mandatory locks on the file.
987 */
988 if (locks_verify_locked(inode))
989 return -EAGAIN;
990
991 vm_flags |= VM_SHARED | VM_MAYSHARE;
992 if (!(file->f_mode & FMODE_WRITE))
993 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
994
995 /* fall through */
996 case MAP_PRIVATE:
997 if (!(file->f_mode & FMODE_READ))
998 return -EACCES;
999 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1000 if (vm_flags & VM_EXEC)
1001 return -EPERM;
1002 vm_flags &= ~VM_MAYEXEC;
1003 }
1004 if (is_file_hugepages(file))
1005 accountable = 0;
1006
1007 if (!file->f_op || !file->f_op->mmap)
1008 return -ENODEV;
1009 break;
1010
1011 default:
1012 return -EINVAL;
1013 }
1014 } else {
1015 switch (flags & MAP_TYPE) {
1016 case MAP_SHARED:
1017 vm_flags |= VM_SHARED | VM_MAYSHARE;
1018 break;
1019 case MAP_PRIVATE:
1020 /*
1021 * Set pgoff according to addr for anon_vma.
1022 */
1023 pgoff = addr >> PAGE_SHIFT;
1024 break;
1025 default:
1026 return -EINVAL;
1027 }
1028 }
1029
1030 error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1031 if (error)
1032 return error;
1033
1034 return mmap_region(file, addr, len, flags, vm_flags, pgoff,
1035 accountable);
1036 }
1037 EXPORT_SYMBOL(do_mmap_pgoff);
1038
1039 /*
1040 * Some shared mappigns will want the pages marked read-only
1041 * to track write events. If so, we'll downgrade vm_page_prot
1042 * to the private version (using protection_map[] without the
1043 * VM_SHARED bit).
1044 */
1045 int vma_wants_writenotify(struct vm_area_struct *vma)
1046 {
1047 unsigned int vm_flags = vma->vm_flags;
1048
1049 /* If it was private or non-writable, the write bit is already clear */
1050 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1051 return 0;
1052
1053 /* The backer wishes to know when pages are first written to? */
1054 if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1055 return 1;
1056
1057 /* The open routine did something to the protections already? */
1058 if (pgprot_val(vma->vm_page_prot) !=
1059 pgprot_val(vm_get_page_prot(vm_flags)))
1060 return 0;
1061
1062 /* Specialty mapping? */
1063 if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1064 return 0;
1065
1066 /* Can the mapping track the dirty pages? */
1067 return vma->vm_file && vma->vm_file->f_mapping &&
1068 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1069 }
1070
1071
1072 unsigned long mmap_region(struct file *file, unsigned long addr,
1073 unsigned long len, unsigned long flags,
1074 unsigned int vm_flags, unsigned long pgoff,
1075 int accountable)
1076 {
1077 struct mm_struct *mm = current->mm;
1078 struct vm_area_struct *vma, *prev;
1079 int correct_wcount = 0;
1080 int error;
1081 struct rb_node **rb_link, *rb_parent;
1082 unsigned long charged = 0;
1083 struct inode *inode = file ? file->f_path.dentry->d_inode : NULL;
1084
1085 /* Clear old maps */
1086 error = -ENOMEM;
1087 munmap_back:
1088 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1089 if (vma && vma->vm_start < addr + len) {
1090 if (do_munmap(mm, addr, len))
1091 return -ENOMEM;
1092 goto munmap_back;
1093 }
1094
1095 /* Check against address space limit. */
1096 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1097 return -ENOMEM;
1098
1099 if (accountable && (!(flags & MAP_NORESERVE) ||
1100 sysctl_overcommit_memory == OVERCOMMIT_NEVER)) {
1101 if (vm_flags & VM_SHARED) {
1102 /* Check memory availability in shmem_file_setup? */
1103 vm_flags |= VM_ACCOUNT;
1104 } else if (vm_flags & VM_WRITE) {
1105 /*
1106 * Private writable mapping: check memory availability
1107 */
1108 charged = len >> PAGE_SHIFT;
1109 if (security_vm_enough_memory(charged))
1110 return -ENOMEM;
1111 vm_flags |= VM_ACCOUNT;
1112 }
1113 }
1114
1115 /*
1116 * Can we just expand an old private anonymous mapping?
1117 * The VM_SHARED test is necessary because shmem_zero_setup
1118 * will create the file object for a shared anonymous map below.
1119 */
1120 if (!file && !(vm_flags & VM_SHARED) &&
1121 vma_merge(mm, prev, addr, addr + len, vm_flags,
1122 NULL, NULL, pgoff, NULL))
1123 goto out;
1124
1125 /*
1126 * Determine the object being mapped and call the appropriate
1127 * specific mapper. the address has already been validated, but
1128 * not unmapped, but the maps are removed from the list.
1129 */
1130 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1131 if (!vma) {
1132 error = -ENOMEM;
1133 goto unacct_error;
1134 }
1135
1136 vma->vm_mm = mm;
1137 vma->vm_start = addr;
1138 vma->vm_end = addr + len;
1139 vma->vm_flags = vm_flags;
1140 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1141 vma->vm_pgoff = pgoff;
1142
1143 if (file) {
1144 error = -EINVAL;
1145 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1146 goto free_vma;
1147 if (vm_flags & VM_DENYWRITE) {
1148 error = deny_write_access(file);
1149 if (error)
1150 goto free_vma;
1151 correct_wcount = 1;
1152 }
1153 vma->vm_file = file;
1154 get_file(file);
1155 error = file->f_op->mmap(file, vma);
1156 if (error)
1157 goto unmap_and_free_vma;
1158 } else if (vm_flags & VM_SHARED) {
1159 error = shmem_zero_setup(vma);
1160 if (error)
1161 goto free_vma;
1162 }
1163
1164 /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform
1165 * shmem_zero_setup (perhaps called through /dev/zero's ->mmap)
1166 * that memory reservation must be checked; but that reservation
1167 * belongs to shared memory object, not to vma: so now clear it.
1168 */
1169 if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT))
1170 vma->vm_flags &= ~VM_ACCOUNT;
1171
1172 /* Can addr have changed??
1173 *
1174 * Answer: Yes, several device drivers can do it in their
1175 * f_op->mmap method. -DaveM
1176 */
1177 addr = vma->vm_start;
1178 pgoff = vma->vm_pgoff;
1179 vm_flags = vma->vm_flags;
1180
1181 if (vma_wants_writenotify(vma))
1182 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1183
1184 if (!file || !vma_merge(mm, prev, addr, vma->vm_end,
1185 vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) {
1186 file = vma->vm_file;
1187 vma_link(mm, vma, prev, rb_link, rb_parent);
1188 if (correct_wcount)
1189 atomic_inc(&inode->i_writecount);
1190 } else {
1191 if (file) {
1192 if (correct_wcount)
1193 atomic_inc(&inode->i_writecount);
1194 fput(file);
1195 }
1196 mpol_free(vma_policy(vma));
1197 kmem_cache_free(vm_area_cachep, vma);
1198 }
1199 out:
1200 mm->total_vm += len >> PAGE_SHIFT;
1201 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1202 if (vm_flags & VM_LOCKED) {
1203 mm->locked_vm += len >> PAGE_SHIFT;
1204 make_pages_present(addr, addr + len);
1205 }
1206 if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1207 make_pages_present(addr, addr + len);
1208 return addr;
1209
1210 unmap_and_free_vma:
1211 if (correct_wcount)
1212 atomic_inc(&inode->i_writecount);
1213 vma->vm_file = NULL;
1214 fput(file);
1215
1216 /* Undo any partial mapping done by a device driver. */
1217 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1218 charged = 0;
1219 free_vma:
1220 kmem_cache_free(vm_area_cachep, vma);
1221 unacct_error:
1222 if (charged)
1223 vm_unacct_memory(charged);
1224 return error;
1225 }
1226
1227 /* Get an address range which is currently unmapped.
1228 * For shmat() with addr=0.
1229 *
1230 * Ugly calling convention alert:
1231 * Return value with the low bits set means error value,
1232 * ie
1233 * if (ret & ~PAGE_MASK)
1234 * error = ret;
1235 *
1236 * This function "knows" that -ENOMEM has the bits set.
1237 */
1238 #ifndef HAVE_ARCH_UNMAPPED_AREA
1239 unsigned long
1240 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1241 unsigned long len, unsigned long pgoff, unsigned long flags)
1242 {
1243 struct mm_struct *mm = current->mm;
1244 struct vm_area_struct *vma;
1245 unsigned long start_addr;
1246
1247 if (len > TASK_SIZE)
1248 return -ENOMEM;
1249
1250 if (flags & MAP_FIXED)
1251 return addr;
1252
1253 if (addr) {
1254 addr = PAGE_ALIGN(addr);
1255 vma = find_vma(mm, addr);
1256 if (TASK_SIZE - len >= addr &&
1257 (!vma || addr + len <= vma->vm_start))
1258 return addr;
1259 }
1260 if (len > mm->cached_hole_size) {
1261 start_addr = addr = mm->free_area_cache;
1262 } else {
1263 start_addr = addr = TASK_UNMAPPED_BASE;
1264 mm->cached_hole_size = 0;
1265 }
1266
1267 full_search:
1268 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1269 /* At this point: (!vma || addr < vma->vm_end). */
1270 if (TASK_SIZE - len < addr) {
1271 /*
1272 * Start a new search - just in case we missed
1273 * some holes.
1274 */
1275 if (start_addr != TASK_UNMAPPED_BASE) {
1276 addr = TASK_UNMAPPED_BASE;
1277 start_addr = addr;
1278 mm->cached_hole_size = 0;
1279 goto full_search;
1280 }
1281 return -ENOMEM;
1282 }
1283 if (!vma || addr + len <= vma->vm_start) {
1284 /*
1285 * Remember the place where we stopped the search:
1286 */
1287 mm->free_area_cache = addr + len;
1288 return addr;
1289 }
1290 if (addr + mm->cached_hole_size < vma->vm_start)
1291 mm->cached_hole_size = vma->vm_start - addr;
1292 addr = vma->vm_end;
1293 }
1294 }
1295 #endif
1296
1297 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1298 {
1299 /*
1300 * Is this a new hole at the lowest possible address?
1301 */
1302 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1303 mm->free_area_cache = addr;
1304 mm->cached_hole_size = ~0UL;
1305 }
1306 }
1307
1308 /*
1309 * This mmap-allocator allocates new areas top-down from below the
1310 * stack's low limit (the base):
1311 */
1312 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1313 unsigned long
1314 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1315 const unsigned long len, const unsigned long pgoff,
1316 const unsigned long flags)
1317 {
1318 struct vm_area_struct *vma;
1319 struct mm_struct *mm = current->mm;
1320 unsigned long addr = addr0;
1321
1322 /* requested length too big for entire address space */
1323 if (len > TASK_SIZE)
1324 return -ENOMEM;
1325
1326 if (flags & MAP_FIXED)
1327 return addr;
1328
1329 /* requesting a specific address */
1330 if (addr) {
1331 addr = PAGE_ALIGN(addr);
1332 vma = find_vma(mm, addr);
1333 if (TASK_SIZE - len >= addr &&
1334 (!vma || addr + len <= vma->vm_start))
1335 return addr;
1336 }
1337
1338 /* check if free_area_cache is useful for us */
1339 if (len <= mm->cached_hole_size) {
1340 mm->cached_hole_size = 0;
1341 mm->free_area_cache = mm->mmap_base;
1342 }
1343
1344 /* either no address requested or can't fit in requested address hole */
1345 addr = mm->free_area_cache;
1346
1347 /* make sure it can fit in the remaining address space */
1348 if (addr > len) {
1349 vma = find_vma(mm, addr-len);
1350 if (!vma || addr <= vma->vm_start)
1351 /* remember the address as a hint for next time */
1352 return (mm->free_area_cache = addr-len);
1353 }
1354
1355 if (mm->mmap_base < len)
1356 goto bottomup;
1357
1358 addr = mm->mmap_base-len;
1359
1360 do {
1361 /*
1362 * Lookup failure means no vma is above this address,
1363 * else if new region fits below vma->vm_start,
1364 * return with success:
1365 */
1366 vma = find_vma(mm, addr);
1367 if (!vma || addr+len <= vma->vm_start)
1368 /* remember the address as a hint for next time */
1369 return (mm->free_area_cache = addr);
1370
1371 /* remember the largest hole we saw so far */
1372 if (addr + mm->cached_hole_size < vma->vm_start)
1373 mm->cached_hole_size = vma->vm_start - addr;
1374
1375 /* try just below the current vma->vm_start */
1376 addr = vma->vm_start-len;
1377 } while (len < vma->vm_start);
1378
1379 bottomup:
1380 /*
1381 * A failed mmap() very likely causes application failure,
1382 * so fall back to the bottom-up function here. This scenario
1383 * can happen with large stack limits and large mmap()
1384 * allocations.
1385 */
1386 mm->cached_hole_size = ~0UL;
1387 mm->free_area_cache = TASK_UNMAPPED_BASE;
1388 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1389 /*
1390 * Restore the topdown base:
1391 */
1392 mm->free_area_cache = mm->mmap_base;
1393 mm->cached_hole_size = ~0UL;
1394
1395 return addr;
1396 }
1397 #endif
1398
1399 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1400 {
1401 /*
1402 * Is this a new hole at the highest possible address?
1403 */
1404 if (addr > mm->free_area_cache)
1405 mm->free_area_cache = addr;
1406
1407 /* dont allow allocations above current base */
1408 if (mm->free_area_cache > mm->mmap_base)
1409 mm->free_area_cache = mm->mmap_base;
1410 }
1411
1412 unsigned long
1413 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1414 unsigned long pgoff, unsigned long flags)
1415 {
1416 unsigned long (*get_area)(struct file *, unsigned long,
1417 unsigned long, unsigned long, unsigned long);
1418
1419 get_area = current->mm->get_unmapped_area;
1420 if (file && file->f_op && file->f_op->get_unmapped_area)
1421 get_area = file->f_op->get_unmapped_area;
1422 addr = get_area(file, addr, len, pgoff, flags);
1423 if (IS_ERR_VALUE(addr))
1424 return addr;
1425
1426 if (addr > TASK_SIZE - len)
1427 return -ENOMEM;
1428 if (addr & ~PAGE_MASK)
1429 return -EINVAL;
1430
1431 return arch_rebalance_pgtables(addr, len);
1432 }
1433
1434 EXPORT_SYMBOL(get_unmapped_area);
1435
1436 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1437 struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr)
1438 {
1439 struct vm_area_struct *vma = NULL;
1440
1441 if (mm) {
1442 /* Check the cache first. */
1443 /* (Cache hit rate is typically around 35%.) */
1444 vma = mm->mmap_cache;
1445 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1446 struct rb_node * rb_node;
1447
1448 rb_node = mm->mm_rb.rb_node;
1449 vma = NULL;
1450
1451 while (rb_node) {
1452 struct vm_area_struct * vma_tmp;
1453
1454 vma_tmp = rb_entry(rb_node,
1455 struct vm_area_struct, vm_rb);
1456
1457 if (vma_tmp->vm_end > addr) {
1458 vma = vma_tmp;
1459 if (vma_tmp->vm_start <= addr)
1460 break;
1461 rb_node = rb_node->rb_left;
1462 } else
1463 rb_node = rb_node->rb_right;
1464 }
1465 if (vma)
1466 mm->mmap_cache = vma;
1467 }
1468 }
1469 return vma;
1470 }
1471
1472 EXPORT_SYMBOL(find_vma);
1473
1474 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1475 struct vm_area_struct *
1476 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1477 struct vm_area_struct **pprev)
1478 {
1479 struct vm_area_struct *vma = NULL, *prev = NULL;
1480 struct rb_node * rb_node;
1481 if (!mm)
1482 goto out;
1483
1484 /* Guard against addr being lower than the first VMA */
1485 vma = mm->mmap;
1486
1487 /* Go through the RB tree quickly. */
1488 rb_node = mm->mm_rb.rb_node;
1489
1490 while (rb_node) {
1491 struct vm_area_struct *vma_tmp;
1492 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1493
1494 if (addr < vma_tmp->vm_end) {
1495 rb_node = rb_node->rb_left;
1496 } else {
1497 prev = vma_tmp;
1498 if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1499 break;
1500 rb_node = rb_node->rb_right;
1501 }
1502 }
1503
1504 out:
1505 *pprev = prev;
1506 return prev ? prev->vm_next : vma;
1507 }
1508
1509 /*
1510 * Verify that the stack growth is acceptable and
1511 * update accounting. This is shared with both the
1512 * grow-up and grow-down cases.
1513 */
1514 static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow)
1515 {
1516 struct mm_struct *mm = vma->vm_mm;
1517 struct rlimit *rlim = current->signal->rlim;
1518 unsigned long new_start;
1519
1520 /* address space limit tests */
1521 if (!may_expand_vm(mm, grow))
1522 return -ENOMEM;
1523
1524 /* Stack limit test */
1525 if (size > rlim[RLIMIT_STACK].rlim_cur)
1526 return -ENOMEM;
1527
1528 /* mlock limit tests */
1529 if (vma->vm_flags & VM_LOCKED) {
1530 unsigned long locked;
1531 unsigned long limit;
1532 locked = mm->locked_vm + grow;
1533 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
1534 if (locked > limit && !capable(CAP_IPC_LOCK))
1535 return -ENOMEM;
1536 }
1537
1538 /* Check to ensure the stack will not grow into a hugetlb-only region */
1539 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1540 vma->vm_end - size;
1541 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1542 return -EFAULT;
1543
1544 /*
1545 * Overcommit.. This must be the final test, as it will
1546 * update security statistics.
1547 */
1548 if (security_vm_enough_memory(grow))
1549 return -ENOMEM;
1550
1551 /* Ok, everything looks good - let it rip */
1552 mm->total_vm += grow;
1553 if (vma->vm_flags & VM_LOCKED)
1554 mm->locked_vm += grow;
1555 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1556 return 0;
1557 }
1558
1559 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1560 /*
1561 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1562 * vma is the last one with address > vma->vm_end. Have to extend vma.
1563 */
1564 #ifndef CONFIG_IA64
1565 static inline
1566 #endif
1567 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1568 {
1569 int error;
1570
1571 if (!(vma->vm_flags & VM_GROWSUP))
1572 return -EFAULT;
1573
1574 /*
1575 * We must make sure the anon_vma is allocated
1576 * so that the anon_vma locking is not a noop.
1577 */
1578 if (unlikely(anon_vma_prepare(vma)))
1579 return -ENOMEM;
1580 anon_vma_lock(vma);
1581
1582 /*
1583 * vma->vm_start/vm_end cannot change under us because the caller
1584 * is required to hold the mmap_sem in read mode. We need the
1585 * anon_vma lock to serialize against concurrent expand_stacks.
1586 * Also guard against wrapping around to address 0.
1587 */
1588 if (address < PAGE_ALIGN(address+4))
1589 address = PAGE_ALIGN(address+4);
1590 else {
1591 anon_vma_unlock(vma);
1592 return -ENOMEM;
1593 }
1594 error = 0;
1595
1596 /* Somebody else might have raced and expanded it already */
1597 if (address > vma->vm_end) {
1598 unsigned long size, grow;
1599
1600 size = address - vma->vm_start;
1601 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1602
1603 error = acct_stack_growth(vma, size, grow);
1604 if (!error)
1605 vma->vm_end = address;
1606 }
1607 anon_vma_unlock(vma);
1608 return error;
1609 }
1610 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1611
1612 /*
1613 * vma is the first one with address < vma->vm_start. Have to extend vma.
1614 */
1615 static inline int expand_downwards(struct vm_area_struct *vma,
1616 unsigned long address)
1617 {
1618 int error;
1619
1620 /*
1621 * We must make sure the anon_vma is allocated
1622 * so that the anon_vma locking is not a noop.
1623 */
1624 if (unlikely(anon_vma_prepare(vma)))
1625 return -ENOMEM;
1626
1627 address &= PAGE_MASK;
1628 error = security_file_mmap(NULL, 0, 0, 0, address, 1);
1629 if (error)
1630 return error;
1631
1632 anon_vma_lock(vma);
1633
1634 /*
1635 * vma->vm_start/vm_end cannot change under us because the caller
1636 * is required to hold the mmap_sem in read mode. We need the
1637 * anon_vma lock to serialize against concurrent expand_stacks.
1638 */
1639
1640 /* Somebody else might have raced and expanded it already */
1641 if (address < vma->vm_start) {
1642 unsigned long size, grow;
1643
1644 size = vma->vm_end - address;
1645 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1646
1647 error = acct_stack_growth(vma, size, grow);
1648 if (!error) {
1649 vma->vm_start = address;
1650 vma->vm_pgoff -= grow;
1651 }
1652 }
1653 anon_vma_unlock(vma);
1654 return error;
1655 }
1656
1657 int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
1658 {
1659 return expand_downwards(vma, address);
1660 }
1661
1662 #ifdef CONFIG_STACK_GROWSUP
1663 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1664 {
1665 return expand_upwards(vma, address);
1666 }
1667
1668 struct vm_area_struct *
1669 find_extend_vma(struct mm_struct *mm, unsigned long addr)
1670 {
1671 struct vm_area_struct *vma, *prev;
1672
1673 addr &= PAGE_MASK;
1674 vma = find_vma_prev(mm, addr, &prev);
1675 if (vma && (vma->vm_start <= addr))
1676 return vma;
1677 if (!prev || expand_stack(prev, addr))
1678 return NULL;
1679 if (prev->vm_flags & VM_LOCKED)
1680 make_pages_present(addr, prev->vm_end);
1681 return prev;
1682 }
1683 #else
1684 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1685 {
1686 return expand_downwards(vma, address);
1687 }
1688
1689 struct vm_area_struct *
1690 find_extend_vma(struct mm_struct * mm, unsigned long addr)
1691 {
1692 struct vm_area_struct * vma;
1693 unsigned long start;
1694
1695 addr &= PAGE_MASK;
1696 vma = find_vma(mm,addr);
1697 if (!vma)
1698 return NULL;
1699 if (vma->vm_start <= addr)
1700 return vma;
1701 if (!(vma->vm_flags & VM_GROWSDOWN))
1702 return NULL;
1703 start = vma->vm_start;
1704 if (expand_stack(vma, addr))
1705 return NULL;
1706 if (vma->vm_flags & VM_LOCKED)
1707 make_pages_present(addr, start);
1708 return vma;
1709 }
1710 #endif
1711
1712 /*
1713 * Ok - we have the memory areas we should free on the vma list,
1714 * so release them, and do the vma updates.
1715 *
1716 * Called with the mm semaphore held.
1717 */
1718 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1719 {
1720 /* Update high watermark before we lower total_vm */
1721 update_hiwater_vm(mm);
1722 do {
1723 long nrpages = vma_pages(vma);
1724
1725 mm->total_vm -= nrpages;
1726 if (vma->vm_flags & VM_LOCKED)
1727 mm->locked_vm -= nrpages;
1728 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1729 vma = remove_vma(vma);
1730 } while (vma);
1731 validate_mm(mm);
1732 }
1733
1734 /*
1735 * Get rid of page table information in the indicated region.
1736 *
1737 * Called with the mm semaphore held.
1738 */
1739 static void unmap_region(struct mm_struct *mm,
1740 struct vm_area_struct *vma, struct vm_area_struct *prev,
1741 unsigned long start, unsigned long end)
1742 {
1743 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1744 struct mmu_gather *tlb;
1745 unsigned long nr_accounted = 0;
1746
1747 lru_add_drain();
1748 tlb = tlb_gather_mmu(mm, 0);
1749 update_hiwater_rss(mm);
1750 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1751 vm_unacct_memory(nr_accounted);
1752 free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
1753 next? next->vm_start: 0);
1754 tlb_finish_mmu(tlb, start, end);
1755 }
1756
1757 /*
1758 * Create a list of vma's touched by the unmap, removing them from the mm's
1759 * vma list as we go..
1760 */
1761 static void
1762 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1763 struct vm_area_struct *prev, unsigned long end)
1764 {
1765 struct vm_area_struct **insertion_point;
1766 struct vm_area_struct *tail_vma = NULL;
1767 unsigned long addr;
1768
1769 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1770 do {
1771 rb_erase(&vma->vm_rb, &mm->mm_rb);
1772 mm->map_count--;
1773 tail_vma = vma;
1774 vma = vma->vm_next;
1775 } while (vma && vma->vm_start < end);
1776 *insertion_point = vma;
1777 tail_vma->vm_next = NULL;
1778 if (mm->unmap_area == arch_unmap_area)
1779 addr = prev ? prev->vm_end : mm->mmap_base;
1780 else
1781 addr = vma ? vma->vm_start : mm->mmap_base;
1782 mm->unmap_area(mm, addr);
1783 mm->mmap_cache = NULL; /* Kill the cache. */
1784 }
1785
1786 /*
1787 * Split a vma into two pieces at address 'addr', a new vma is allocated
1788 * either for the first part or the tail.
1789 */
1790 int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1791 unsigned long addr, int new_below)
1792 {
1793 struct mempolicy *pol;
1794 struct vm_area_struct *new;
1795
1796 if (is_vm_hugetlb_page(vma) && (addr & ~HPAGE_MASK))
1797 return -EINVAL;
1798
1799 if (mm->map_count >= sysctl_max_map_count)
1800 return -ENOMEM;
1801
1802 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1803 if (!new)
1804 return -ENOMEM;
1805
1806 /* most fields are the same, copy all, and then fixup */
1807 *new = *vma;
1808
1809 if (new_below)
1810 new->vm_end = addr;
1811 else {
1812 new->vm_start = addr;
1813 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1814 }
1815
1816 pol = mpol_copy(vma_policy(vma));
1817 if (IS_ERR(pol)) {
1818 kmem_cache_free(vm_area_cachep, new);
1819 return PTR_ERR(pol);
1820 }
1821 vma_set_policy(new, pol);
1822
1823 if (new->vm_file)
1824 get_file(new->vm_file);
1825
1826 if (new->vm_ops && new->vm_ops->open)
1827 new->vm_ops->open(new);
1828
1829 if (new_below)
1830 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1831 ((addr - new->vm_start) >> PAGE_SHIFT), new);
1832 else
1833 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
1834
1835 return 0;
1836 }
1837
1838 /* Munmap is split into 2 main parts -- this part which finds
1839 * what needs doing, and the areas themselves, which do the
1840 * work. This now handles partial unmappings.
1841 * Jeremy Fitzhardinge <jeremy@goop.org>
1842 */
1843 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1844 {
1845 unsigned long end;
1846 struct vm_area_struct *vma, *prev, *last;
1847
1848 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
1849 return -EINVAL;
1850
1851 if ((len = PAGE_ALIGN(len)) == 0)
1852 return -EINVAL;
1853
1854 /* Find the first overlapping VMA */
1855 vma = find_vma_prev(mm, start, &prev);
1856 if (!vma)
1857 return 0;
1858 /* we have start < vma->vm_end */
1859
1860 /* if it doesn't overlap, we have nothing.. */
1861 end = start + len;
1862 if (vma->vm_start >= end)
1863 return 0;
1864
1865 /*
1866 * If we need to split any vma, do it now to save pain later.
1867 *
1868 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
1869 * unmapped vm_area_struct will remain in use: so lower split_vma
1870 * places tmp vma above, and higher split_vma places tmp vma below.
1871 */
1872 if (start > vma->vm_start) {
1873 int error = split_vma(mm, vma, start, 0);
1874 if (error)
1875 return error;
1876 prev = vma;
1877 }
1878
1879 /* Does it split the last one? */
1880 last = find_vma(mm, end);
1881 if (last && end > last->vm_start) {
1882 int error = split_vma(mm, last, end, 1);
1883 if (error)
1884 return error;
1885 }
1886 vma = prev? prev->vm_next: mm->mmap;
1887
1888 /*
1889 * Remove the vma's, and unmap the actual pages
1890 */
1891 detach_vmas_to_be_unmapped(mm, vma, prev, end);
1892 unmap_region(mm, vma, prev, start, end);
1893
1894 /* Fix up all other VM information */
1895 remove_vma_list(mm, vma);
1896
1897 return 0;
1898 }
1899
1900 EXPORT_SYMBOL(do_munmap);
1901
1902 asmlinkage long sys_munmap(unsigned long addr, size_t len)
1903 {
1904 int ret;
1905 struct mm_struct *mm = current->mm;
1906
1907 profile_munmap(addr);
1908
1909 down_write(&mm->mmap_sem);
1910 ret = do_munmap(mm, addr, len);
1911 up_write(&mm->mmap_sem);
1912 return ret;
1913 }
1914
1915 static inline void verify_mm_writelocked(struct mm_struct *mm)
1916 {
1917 #ifdef CONFIG_DEBUG_VM
1918 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
1919 WARN_ON(1);
1920 up_read(&mm->mmap_sem);
1921 }
1922 #endif
1923 }
1924
1925 /*
1926 * this is really a simplified "do_mmap". it only handles
1927 * anonymous maps. eventually we may be able to do some
1928 * brk-specific accounting here.
1929 */
1930 unsigned long do_brk(unsigned long addr, unsigned long len)
1931 {
1932 struct mm_struct * mm = current->mm;
1933 struct vm_area_struct * vma, * prev;
1934 unsigned long flags;
1935 struct rb_node ** rb_link, * rb_parent;
1936 pgoff_t pgoff = addr >> PAGE_SHIFT;
1937 int error;
1938
1939 len = PAGE_ALIGN(len);
1940 if (!len)
1941 return addr;
1942
1943 if ((addr + len) > TASK_SIZE || (addr + len) < addr)
1944 return -EINVAL;
1945
1946 if (is_hugepage_only_range(mm, addr, len))
1947 return -EINVAL;
1948
1949 error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
1950 if (error)
1951 return error;
1952
1953 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
1954
1955 error = arch_mmap_check(addr, len, flags);
1956 if (error)
1957 return error;
1958
1959 /*
1960 * mlock MCL_FUTURE?
1961 */
1962 if (mm->def_flags & VM_LOCKED) {
1963 unsigned long locked, lock_limit;
1964 locked = len >> PAGE_SHIFT;
1965 locked += mm->locked_vm;
1966 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
1967 lock_limit >>= PAGE_SHIFT;
1968 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1969 return -EAGAIN;
1970 }
1971
1972 /*
1973 * mm->mmap_sem is required to protect against another thread
1974 * changing the mappings in case we sleep.
1975 */
1976 verify_mm_writelocked(mm);
1977
1978 /*
1979 * Clear old maps. this also does some error checking for us
1980 */
1981 munmap_back:
1982 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1983 if (vma && vma->vm_start < addr + len) {
1984 if (do_munmap(mm, addr, len))
1985 return -ENOMEM;
1986 goto munmap_back;
1987 }
1988
1989 /* Check against address space limits *after* clearing old maps... */
1990 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1991 return -ENOMEM;
1992
1993 if (mm->map_count > sysctl_max_map_count)
1994 return -ENOMEM;
1995
1996 if (security_vm_enough_memory(len >> PAGE_SHIFT))
1997 return -ENOMEM;
1998
1999 /* Can we just expand an old private anonymous mapping? */
2000 if (vma_merge(mm, prev, addr, addr + len, flags,
2001 NULL, NULL, pgoff, NULL))
2002 goto out;
2003
2004 /*
2005 * create a vma struct for an anonymous mapping
2006 */
2007 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2008 if (!vma) {
2009 vm_unacct_memory(len >> PAGE_SHIFT);
2010 return -ENOMEM;
2011 }
2012
2013 vma->vm_mm = mm;
2014 vma->vm_start = addr;
2015 vma->vm_end = addr + len;
2016 vma->vm_pgoff = pgoff;
2017 vma->vm_flags = flags;
2018 vma->vm_page_prot = vm_get_page_prot(flags);
2019 vma_link(mm, vma, prev, rb_link, rb_parent);
2020 out:
2021 mm->total_vm += len >> PAGE_SHIFT;
2022 if (flags & VM_LOCKED) {
2023 mm->locked_vm += len >> PAGE_SHIFT;
2024 make_pages_present(addr, addr + len);
2025 }
2026 return addr;
2027 }
2028
2029 EXPORT_SYMBOL(do_brk);
2030
2031 /* Release all mmaps. */
2032 void exit_mmap(struct mm_struct *mm)
2033 {
2034 struct mmu_gather *tlb;
2035 struct vm_area_struct *vma = mm->mmap;
2036 unsigned long nr_accounted = 0;
2037 unsigned long end;
2038
2039 /* mm's last user has gone, and its about to be pulled down */
2040 arch_exit_mmap(mm);
2041
2042 lru_add_drain();
2043 flush_cache_mm(mm);
2044 tlb = tlb_gather_mmu(mm, 1);
2045 /* Don't update_hiwater_rss(mm) here, do_exit already did */
2046 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2047 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
2048 vm_unacct_memory(nr_accounted);
2049 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
2050 tlb_finish_mmu(tlb, 0, end);
2051
2052 /*
2053 * Walk the list again, actually closing and freeing it,
2054 * with preemption enabled, without holding any MM locks.
2055 */
2056 while (vma)
2057 vma = remove_vma(vma);
2058
2059 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2060 }
2061
2062 /* Insert vm structure into process list sorted by address
2063 * and into the inode's i_mmap tree. If vm_file is non-NULL
2064 * then i_mmap_lock is taken here.
2065 */
2066 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2067 {
2068 struct vm_area_struct * __vma, * prev;
2069 struct rb_node ** rb_link, * rb_parent;
2070
2071 /*
2072 * The vm_pgoff of a purely anonymous vma should be irrelevant
2073 * until its first write fault, when page's anon_vma and index
2074 * are set. But now set the vm_pgoff it will almost certainly
2075 * end up with (unless mremap moves it elsewhere before that
2076 * first wfault), so /proc/pid/maps tells a consistent story.
2077 *
2078 * By setting it to reflect the virtual start address of the
2079 * vma, merges and splits can happen in a seamless way, just
2080 * using the existing file pgoff checks and manipulations.
2081 * Similarly in do_mmap_pgoff and in do_brk.
2082 */
2083 if (!vma->vm_file) {
2084 BUG_ON(vma->anon_vma);
2085 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2086 }
2087 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2088 if (__vma && __vma->vm_start < vma->vm_end)
2089 return -ENOMEM;
2090 if ((vma->vm_flags & VM_ACCOUNT) &&
2091 security_vm_enough_memory_mm(mm, vma_pages(vma)))
2092 return -ENOMEM;
2093 vma_link(mm, vma, prev, rb_link, rb_parent);
2094 return 0;
2095 }
2096
2097 /*
2098 * Copy the vma structure to a new location in the same mm,
2099 * prior to moving page table entries, to effect an mremap move.
2100 */
2101 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2102 unsigned long addr, unsigned long len, pgoff_t pgoff)
2103 {
2104 struct vm_area_struct *vma = *vmap;
2105 unsigned long vma_start = vma->vm_start;
2106 struct mm_struct *mm = vma->vm_mm;
2107 struct vm_area_struct *new_vma, *prev;
2108 struct rb_node **rb_link, *rb_parent;
2109 struct mempolicy *pol;
2110
2111 /*
2112 * If anonymous vma has not yet been faulted, update new pgoff
2113 * to match new location, to increase its chance of merging.
2114 */
2115 if (!vma->vm_file && !vma->anon_vma)
2116 pgoff = addr >> PAGE_SHIFT;
2117
2118 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2119 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2120 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2121 if (new_vma) {
2122 /*
2123 * Source vma may have been merged into new_vma
2124 */
2125 if (vma_start >= new_vma->vm_start &&
2126 vma_start < new_vma->vm_end)
2127 *vmap = new_vma;
2128 } else {
2129 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2130 if (new_vma) {
2131 *new_vma = *vma;
2132 pol = mpol_copy(vma_policy(vma));
2133 if (IS_ERR(pol)) {
2134 kmem_cache_free(vm_area_cachep, new_vma);
2135 return NULL;
2136 }
2137 vma_set_policy(new_vma, pol);
2138 new_vma->vm_start = addr;
2139 new_vma->vm_end = addr + len;
2140 new_vma->vm_pgoff = pgoff;
2141 if (new_vma->vm_file)
2142 get_file(new_vma->vm_file);
2143 if (new_vma->vm_ops && new_vma->vm_ops->open)
2144 new_vma->vm_ops->open(new_vma);
2145 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2146 }
2147 }
2148 return new_vma;
2149 }
2150
2151 /*
2152 * Return true if the calling process may expand its vm space by the passed
2153 * number of pages
2154 */
2155 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2156 {
2157 unsigned long cur = mm->total_vm; /* pages */
2158 unsigned long lim;
2159
2160 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
2161
2162 if (cur + npages > lim)
2163 return 0;
2164 return 1;
2165 }
2166
2167
2168 static int special_mapping_fault(struct vm_area_struct *vma,
2169 struct vm_fault *vmf)
2170 {
2171 pgoff_t pgoff;
2172 struct page **pages;
2173
2174 /*
2175 * special mappings have no vm_file, and in that case, the mm
2176 * uses vm_pgoff internally. So we have to subtract it from here.
2177 * We are allowed to do this because we are the mm; do not copy
2178 * this code into drivers!
2179 */
2180 pgoff = vmf->pgoff - vma->vm_pgoff;
2181
2182 for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2183 pgoff--;
2184
2185 if (*pages) {
2186 struct page *page = *pages;
2187 get_page(page);
2188 vmf->page = page;
2189 return 0;
2190 }
2191
2192 return VM_FAULT_SIGBUS;
2193 }
2194
2195 /*
2196 * Having a close hook prevents vma merging regardless of flags.
2197 */
2198 static void special_mapping_close(struct vm_area_struct *vma)
2199 {
2200 }
2201
2202 static struct vm_operations_struct special_mapping_vmops = {
2203 .close = special_mapping_close,
2204 .fault = special_mapping_fault,
2205 };
2206
2207 /*
2208 * Called with mm->mmap_sem held for writing.
2209 * Insert a new vma covering the given region, with the given flags.
2210 * Its pages are supplied by the given array of struct page *.
2211 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2212 * The region past the last page supplied will always produce SIGBUS.
2213 * The array pointer and the pages it points to are assumed to stay alive
2214 * for as long as this mapping might exist.
2215 */
2216 int install_special_mapping(struct mm_struct *mm,
2217 unsigned long addr, unsigned long len,
2218 unsigned long vm_flags, struct page **pages)
2219 {
2220 struct vm_area_struct *vma;
2221
2222 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2223 if (unlikely(vma == NULL))
2224 return -ENOMEM;
2225
2226 vma->vm_mm = mm;
2227 vma->vm_start = addr;
2228 vma->vm_end = addr + len;
2229
2230 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2231 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2232
2233 vma->vm_ops = &special_mapping_vmops;
2234 vma->vm_private_data = pages;
2235
2236 if (unlikely(insert_vm_struct(mm, vma))) {
2237 kmem_cache_free(vm_area_cachep, vma);
2238 return -ENOMEM;
2239 }
2240
2241 mm->total_vm += len >> PAGE_SHIFT;
2242
2243 return 0;
2244 }