Loading...
1/*
2 * mm/mmap.c
3 *
4 * Written by obz.
5 *
6 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
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#include <linux/mmu_notifier.h>
30#include <linux/perf_event.h>
31#include <linux/audit.h>
32#include <linux/khugepaged.h>
33
34#include <asm/uaccess.h>
35#include <asm/cacheflush.h>
36#include <asm/tlb.h>
37#include <asm/mmu_context.h>
38
39#include "internal.h"
40
41#ifndef arch_mmap_check
42#define arch_mmap_check(addr, len, flags) (0)
43#endif
44
45#ifndef arch_rebalance_pgtables
46#define arch_rebalance_pgtables(addr, len) (addr)
47#endif
48
49static void unmap_region(struct mm_struct *mm,
50 struct vm_area_struct *vma, struct vm_area_struct *prev,
51 unsigned long start, unsigned long end);
52
53/*
54 * WARNING: the debugging will use recursive algorithms so never enable this
55 * unless you know what you are doing.
56 */
57#undef DEBUG_MM_RB
58
59/* description of effects of mapping type and prot in current implementation.
60 * this is due to the limited x86 page protection hardware. The expected
61 * behavior is in parens:
62 *
63 * map_type prot
64 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
65 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
66 * w: (no) no w: (no) no w: (yes) yes w: (no) no
67 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
68 *
69 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
70 * w: (no) no w: (no) no w: (copy) copy w: (no) no
71 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
72 *
73 */
74pgprot_t protection_map[16] = {
75 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
76 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
77};
78
79pgprot_t vm_get_page_prot(unsigned long vm_flags)
80{
81 return __pgprot(pgprot_val(protection_map[vm_flags &
82 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
83 pgprot_val(arch_vm_get_page_prot(vm_flags)));
84}
85EXPORT_SYMBOL(vm_get_page_prot);
86
87int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; /* heuristic overcommit */
88int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */
89int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
90/*
91 * Make sure vm_committed_as in one cacheline and not cacheline shared with
92 * other variables. It can be updated by several CPUs frequently.
93 */
94struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
95
96/*
97 * Check that a process has enough memory to allocate a new virtual
98 * mapping. 0 means there is enough memory for the allocation to
99 * succeed and -ENOMEM implies there is not.
100 *
101 * We currently support three overcommit policies, which are set via the
102 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
103 *
104 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
105 * Additional code 2002 Jul 20 by Robert Love.
106 *
107 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
108 *
109 * Note this is a helper function intended to be used by LSMs which
110 * wish to use this logic.
111 */
112int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
113{
114 unsigned long free, allowed;
115
116 vm_acct_memory(pages);
117
118 /*
119 * Sometimes we want to use more memory than we have
120 */
121 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
122 return 0;
123
124 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
125 free = global_page_state(NR_FREE_PAGES);
126 free += global_page_state(NR_FILE_PAGES);
127
128 /*
129 * shmem pages shouldn't be counted as free in this
130 * case, they can't be purged, only swapped out, and
131 * that won't affect the overall amount of available
132 * memory in the system.
133 */
134 free -= global_page_state(NR_SHMEM);
135
136 free += nr_swap_pages;
137
138 /*
139 * Any slabs which are created with the
140 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
141 * which are reclaimable, under pressure. The dentry
142 * cache and most inode caches should fall into this
143 */
144 free += global_page_state(NR_SLAB_RECLAIMABLE);
145
146 /*
147 * Leave reserved pages. The pages are not for anonymous pages.
148 */
149 if (free <= totalreserve_pages)
150 goto error;
151 else
152 free -= totalreserve_pages;
153
154 /*
155 * Leave the last 3% for root
156 */
157 if (!cap_sys_admin)
158 free -= free / 32;
159
160 if (free > pages)
161 return 0;
162
163 goto error;
164 }
165
166 allowed = (totalram_pages - hugetlb_total_pages())
167 * sysctl_overcommit_ratio / 100;
168 /*
169 * Leave the last 3% for root
170 */
171 if (!cap_sys_admin)
172 allowed -= allowed / 32;
173 allowed += total_swap_pages;
174
175 /* Don't let a single process grow too big:
176 leave 3% of the size of this process for other processes */
177 if (mm)
178 allowed -= mm->total_vm / 32;
179
180 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
181 return 0;
182error:
183 vm_unacct_memory(pages);
184
185 return -ENOMEM;
186}
187
188/*
189 * Requires inode->i_mapping->i_mmap_mutex
190 */
191static 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 */
211void 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 mutex_lock(&mapping->i_mmap_mutex);
218 __remove_shared_vm_struct(vma, file, mapping);
219 mutex_unlock(&mapping->i_mmap_mutex);
220 }
221}
222
223/*
224 * Close a vm structure and free it, returning the next.
225 */
226static 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 if (vma->vm_flags & VM_EXECUTABLE)
236 removed_exe_file_vma(vma->vm_mm);
237 }
238 mpol_put(vma_policy(vma));
239 kmem_cache_free(vm_area_cachep, vma);
240 return next;
241}
242
243SYSCALL_DEFINE1(brk, unsigned long, brk)
244{
245 unsigned long rlim, retval;
246 unsigned long newbrk, oldbrk;
247 struct mm_struct *mm = current->mm;
248 unsigned long min_brk;
249
250 down_write(&mm->mmap_sem);
251
252#ifdef CONFIG_COMPAT_BRK
253 /*
254 * CONFIG_COMPAT_BRK can still be overridden by setting
255 * randomize_va_space to 2, which will still cause mm->start_brk
256 * to be arbitrarily shifted
257 */
258 if (current->brk_randomized)
259 min_brk = mm->start_brk;
260 else
261 min_brk = mm->end_data;
262#else
263 min_brk = mm->start_brk;
264#endif
265 if (brk < min_brk)
266 goto out;
267
268 /*
269 * Check against rlimit here. If this check is done later after the test
270 * of oldbrk with newbrk then it can escape the test and let the data
271 * segment grow beyond its set limit the in case where the limit is
272 * not page aligned -Ram Gupta
273 */
274 rlim = rlimit(RLIMIT_DATA);
275 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
276 (mm->end_data - mm->start_data) > rlim)
277 goto out;
278
279 newbrk = PAGE_ALIGN(brk);
280 oldbrk = PAGE_ALIGN(mm->brk);
281 if (oldbrk == newbrk)
282 goto set_brk;
283
284 /* Always allow shrinking brk. */
285 if (brk <= mm->brk) {
286 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
287 goto set_brk;
288 goto out;
289 }
290
291 /* Check against existing mmap mappings. */
292 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
293 goto out;
294
295 /* Ok, looks good - let it rip. */
296 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
297 goto out;
298set_brk:
299 mm->brk = brk;
300out:
301 retval = mm->brk;
302 up_write(&mm->mmap_sem);
303 return retval;
304}
305
306#ifdef DEBUG_MM_RB
307static int browse_rb(struct rb_root *root)
308{
309 int i = 0, j;
310 struct rb_node *nd, *pn = NULL;
311 unsigned long prev = 0, pend = 0;
312
313 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
314 struct vm_area_struct *vma;
315 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
316 if (vma->vm_start < prev)
317 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
318 if (vma->vm_start < pend)
319 printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
320 if (vma->vm_start > vma->vm_end)
321 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
322 i++;
323 pn = nd;
324 prev = vma->vm_start;
325 pend = vma->vm_end;
326 }
327 j = 0;
328 for (nd = pn; nd; nd = rb_prev(nd)) {
329 j++;
330 }
331 if (i != j)
332 printk("backwards %d, forwards %d\n", j, i), i = 0;
333 return i;
334}
335
336void validate_mm(struct mm_struct *mm)
337{
338 int bug = 0;
339 int i = 0;
340 struct vm_area_struct *tmp = mm->mmap;
341 while (tmp) {
342 tmp = tmp->vm_next;
343 i++;
344 }
345 if (i != mm->map_count)
346 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
347 i = browse_rb(&mm->mm_rb);
348 if (i != mm->map_count)
349 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
350 BUG_ON(bug);
351}
352#else
353#define validate_mm(mm) do { } while (0)
354#endif
355
356static struct vm_area_struct *
357find_vma_prepare(struct mm_struct *mm, unsigned long addr,
358 struct vm_area_struct **pprev, struct rb_node ***rb_link,
359 struct rb_node ** rb_parent)
360{
361 struct vm_area_struct * vma;
362 struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
363
364 __rb_link = &mm->mm_rb.rb_node;
365 rb_prev = __rb_parent = NULL;
366 vma = NULL;
367
368 while (*__rb_link) {
369 struct vm_area_struct *vma_tmp;
370
371 __rb_parent = *__rb_link;
372 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
373
374 if (vma_tmp->vm_end > addr) {
375 vma = vma_tmp;
376 if (vma_tmp->vm_start <= addr)
377 break;
378 __rb_link = &__rb_parent->rb_left;
379 } else {
380 rb_prev = __rb_parent;
381 __rb_link = &__rb_parent->rb_right;
382 }
383 }
384
385 *pprev = NULL;
386 if (rb_prev)
387 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
388 *rb_link = __rb_link;
389 *rb_parent = __rb_parent;
390 return vma;
391}
392
393void __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
400static 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
422static 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}
430
431static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
432 struct vm_area_struct *prev, struct rb_node **rb_link,
433 struct rb_node *rb_parent)
434{
435 struct address_space *mapping = NULL;
436
437 if (vma->vm_file)
438 mapping = vma->vm_file->f_mapping;
439
440 if (mapping)
441 mutex_lock(&mapping->i_mmap_mutex);
442
443 __vma_link(mm, vma, prev, rb_link, rb_parent);
444 __vma_link_file(vma);
445
446 if (mapping)
447 mutex_unlock(&mapping->i_mmap_mutex);
448
449 mm->map_count++;
450 validate_mm(mm);
451}
452
453/*
454 * Helper for vma_adjust in the split_vma insert case:
455 * insert vm structure into list and rbtree and anon_vma,
456 * but it has already been inserted into prio_tree earlier.
457 */
458static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
459{
460 struct vm_area_struct *__vma, *prev;
461 struct rb_node **rb_link, *rb_parent;
462
463 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
464 BUG_ON(__vma && __vma->vm_start < vma->vm_end);
465 __vma_link(mm, vma, prev, rb_link, rb_parent);
466 mm->map_count++;
467}
468
469static inline void
470__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
471 struct vm_area_struct *prev)
472{
473 struct vm_area_struct *next = vma->vm_next;
474
475 prev->vm_next = next;
476 if (next)
477 next->vm_prev = prev;
478 rb_erase(&vma->vm_rb, &mm->mm_rb);
479 if (mm->mmap_cache == vma)
480 mm->mmap_cache = prev;
481}
482
483/*
484 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
485 * is already present in an i_mmap tree without adjusting the tree.
486 * The following helper function should be used when such adjustments
487 * are necessary. The "insert" vma (if any) is to be inserted
488 * before we drop the necessary locks.
489 */
490int vma_adjust(struct vm_area_struct *vma, unsigned long start,
491 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
492{
493 struct mm_struct *mm = vma->vm_mm;
494 struct vm_area_struct *next = vma->vm_next;
495 struct vm_area_struct *importer = NULL;
496 struct address_space *mapping = NULL;
497 struct prio_tree_root *root = NULL;
498 struct anon_vma *anon_vma = NULL;
499 struct file *file = vma->vm_file;
500 long adjust_next = 0;
501 int remove_next = 0;
502
503 if (next && !insert) {
504 struct vm_area_struct *exporter = NULL;
505
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 */
511again: remove_next = 1 + (end > next->vm_end);
512 end = next->vm_end;
513 exporter = next;
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 exporter = next;
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 exporter = vma;
531 importer = next;
532 }
533
534 /*
535 * Easily overlooked: when mprotect shifts the boundary,
536 * make sure the expanding vma has anon_vma set if the
537 * shrinking vma had, to cover any anon pages imported.
538 */
539 if (exporter && exporter->anon_vma && !importer->anon_vma) {
540 if (anon_vma_clone(importer, exporter))
541 return -ENOMEM;
542 importer->anon_vma = exporter->anon_vma;
543 }
544 }
545
546 if (file) {
547 mapping = file->f_mapping;
548 if (!(vma->vm_flags & VM_NONLINEAR))
549 root = &mapping->i_mmap;
550 mutex_lock(&mapping->i_mmap_mutex);
551 if (insert) {
552 /*
553 * Put into prio_tree now, so instantiated pages
554 * are visible to arm/parisc __flush_dcache_page
555 * throughout; but we cannot insert into address
556 * space until vma start or end is updated.
557 */
558 __vma_link_file(insert);
559 }
560 }
561
562 vma_adjust_trans_huge(vma, start, end, adjust_next);
563
564 /*
565 * When changing only vma->vm_end, we don't really need anon_vma
566 * lock. This is a fairly rare case by itself, but the anon_vma
567 * lock may be shared between many sibling processes. Skipping
568 * the lock for brk adjustments makes a difference sometimes.
569 */
570 if (vma->anon_vma && (importer || start != vma->vm_start)) {
571 anon_vma = vma->anon_vma;
572 anon_vma_lock(anon_vma);
573 }
574
575 if (root) {
576 flush_dcache_mmap_lock(mapping);
577 vma_prio_tree_remove(vma, root);
578 if (adjust_next)
579 vma_prio_tree_remove(next, root);
580 }
581
582 vma->vm_start = start;
583 vma->vm_end = end;
584 vma->vm_pgoff = pgoff;
585 if (adjust_next) {
586 next->vm_start += adjust_next << PAGE_SHIFT;
587 next->vm_pgoff += adjust_next;
588 }
589
590 if (root) {
591 if (adjust_next)
592 vma_prio_tree_insert(next, root);
593 vma_prio_tree_insert(vma, root);
594 flush_dcache_mmap_unlock(mapping);
595 }
596
597 if (remove_next) {
598 /*
599 * vma_merge has merged next into vma, and needs
600 * us to remove next before dropping the locks.
601 */
602 __vma_unlink(mm, next, vma);
603 if (file)
604 __remove_shared_vm_struct(next, file, mapping);
605 } else if (insert) {
606 /*
607 * split_vma has split insert from vma, and needs
608 * us to insert it before dropping the locks
609 * (it may either follow vma or precede it).
610 */
611 __insert_vm_struct(mm, insert);
612 }
613
614 if (anon_vma)
615 anon_vma_unlock(anon_vma);
616 if (mapping)
617 mutex_unlock(&mapping->i_mmap_mutex);
618
619 if (remove_next) {
620 if (file) {
621 fput(file);
622 if (next->vm_flags & VM_EXECUTABLE)
623 removed_exe_file_vma(mm);
624 }
625 if (next->anon_vma)
626 anon_vma_merge(vma, next);
627 mm->map_count--;
628 mpol_put(vma_policy(next));
629 kmem_cache_free(vm_area_cachep, next);
630 /*
631 * In mprotect's case 6 (see comments on vma_merge),
632 * we must remove another next too. It would clutter
633 * up the code too much to do both in one go.
634 */
635 if (remove_next == 2) {
636 next = vma->vm_next;
637 goto again;
638 }
639 }
640
641 validate_mm(mm);
642
643 return 0;
644}
645
646/*
647 * If the vma has a ->close operation then the driver probably needs to release
648 * per-vma resources, so we don't attempt to merge those.
649 */
650static inline int is_mergeable_vma(struct vm_area_struct *vma,
651 struct file *file, unsigned long vm_flags)
652{
653 /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
654 if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR)
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
663static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
664 struct anon_vma *anon_vma2,
665 struct vm_area_struct *vma)
666{
667 /*
668 * The list_is_singular() test is to avoid merging VMA cloned from
669 * parents. This can improve scalability caused by anon_vma lock.
670 */
671 if ((!anon_vma1 || !anon_vma2) && (!vma ||
672 list_is_singular(&vma->anon_vma_chain)))
673 return 1;
674 return anon_vma1 == anon_vma2;
675}
676
677/*
678 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
679 * in front of (at a lower virtual address and file offset than) the vma.
680 *
681 * We cannot merge two vmas if they have differently assigned (non-NULL)
682 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
683 *
684 * We don't check here for the merged mmap wrapping around the end of pagecache
685 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
686 * wrap, nor mmaps which cover the final page at index -1UL.
687 */
688static int
689can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
690 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
691{
692 if (is_mergeable_vma(vma, file, vm_flags) &&
693 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
694 if (vma->vm_pgoff == vm_pgoff)
695 return 1;
696 }
697 return 0;
698}
699
700/*
701 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
702 * beyond (at a higher virtual address and file offset than) the vma.
703 *
704 * We cannot merge two vmas if they have differently assigned (non-NULL)
705 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
706 */
707static int
708can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
709 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
710{
711 if (is_mergeable_vma(vma, file, vm_flags) &&
712 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
713 pgoff_t vm_pglen;
714 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
715 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
716 return 1;
717 }
718 return 0;
719}
720
721/*
722 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
723 * whether that can be merged with its predecessor or its successor.
724 * Or both (it neatly fills a hole).
725 *
726 * In most cases - when called for mmap, brk or mremap - [addr,end) is
727 * certain not to be mapped by the time vma_merge is called; but when
728 * called for mprotect, it is certain to be already mapped (either at
729 * an offset within prev, or at the start of next), and the flags of
730 * this area are about to be changed to vm_flags - and the no-change
731 * case has already been eliminated.
732 *
733 * The following mprotect cases have to be considered, where AAAA is
734 * the area passed down from mprotect_fixup, never extending beyond one
735 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
736 *
737 * AAAA AAAA AAAA AAAA
738 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
739 * cannot merge might become might become might become
740 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
741 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
742 * mremap move: PPPPNNNNNNNN 8
743 * AAAA
744 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
745 * might become case 1 below case 2 below case 3 below
746 *
747 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
748 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
749 */
750struct vm_area_struct *vma_merge(struct mm_struct *mm,
751 struct vm_area_struct *prev, unsigned long addr,
752 unsigned long end, unsigned long vm_flags,
753 struct anon_vma *anon_vma, struct file *file,
754 pgoff_t pgoff, struct mempolicy *policy)
755{
756 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
757 struct vm_area_struct *area, *next;
758 int err;
759
760 /*
761 * We later require that vma->vm_flags == vm_flags,
762 * so this tests vma->vm_flags & VM_SPECIAL, too.
763 */
764 if (vm_flags & VM_SPECIAL)
765 return NULL;
766
767 if (prev)
768 next = prev->vm_next;
769 else
770 next = mm->mmap;
771 area = next;
772 if (next && next->vm_end == end) /* cases 6, 7, 8 */
773 next = next->vm_next;
774
775 /*
776 * Can it merge with the predecessor?
777 */
778 if (prev && prev->vm_end == addr &&
779 mpol_equal(vma_policy(prev), policy) &&
780 can_vma_merge_after(prev, vm_flags,
781 anon_vma, file, pgoff)) {
782 /*
783 * OK, it can. Can we now merge in the successor as well?
784 */
785 if (next && end == next->vm_start &&
786 mpol_equal(policy, vma_policy(next)) &&
787 can_vma_merge_before(next, vm_flags,
788 anon_vma, file, pgoff+pglen) &&
789 is_mergeable_anon_vma(prev->anon_vma,
790 next->anon_vma, NULL)) {
791 /* cases 1, 6 */
792 err = vma_adjust(prev, prev->vm_start,
793 next->vm_end, prev->vm_pgoff, NULL);
794 } else /* cases 2, 5, 7 */
795 err = vma_adjust(prev, prev->vm_start,
796 end, prev->vm_pgoff, NULL);
797 if (err)
798 return NULL;
799 khugepaged_enter_vma_merge(prev);
800 return prev;
801 }
802
803 /*
804 * Can this new request be merged in front of next?
805 */
806 if (next && end == next->vm_start &&
807 mpol_equal(policy, vma_policy(next)) &&
808 can_vma_merge_before(next, vm_flags,
809 anon_vma, file, pgoff+pglen)) {
810 if (prev && addr < prev->vm_end) /* case 4 */
811 err = vma_adjust(prev, prev->vm_start,
812 addr, prev->vm_pgoff, NULL);
813 else /* cases 3, 8 */
814 err = vma_adjust(area, addr, next->vm_end,
815 next->vm_pgoff - pglen, NULL);
816 if (err)
817 return NULL;
818 khugepaged_enter_vma_merge(area);
819 return area;
820 }
821
822 return NULL;
823}
824
825/*
826 * Rough compatbility check to quickly see if it's even worth looking
827 * at sharing an anon_vma.
828 *
829 * They need to have the same vm_file, and the flags can only differ
830 * in things that mprotect may change.
831 *
832 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
833 * we can merge the two vma's. For example, we refuse to merge a vma if
834 * there is a vm_ops->close() function, because that indicates that the
835 * driver is doing some kind of reference counting. But that doesn't
836 * really matter for the anon_vma sharing case.
837 */
838static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
839{
840 return a->vm_end == b->vm_start &&
841 mpol_equal(vma_policy(a), vma_policy(b)) &&
842 a->vm_file == b->vm_file &&
843 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) &&
844 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
845}
846
847/*
848 * Do some basic sanity checking to see if we can re-use the anon_vma
849 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
850 * the same as 'old', the other will be the new one that is trying
851 * to share the anon_vma.
852 *
853 * NOTE! This runs with mm_sem held for reading, so it is possible that
854 * the anon_vma of 'old' is concurrently in the process of being set up
855 * by another page fault trying to merge _that_. But that's ok: if it
856 * is being set up, that automatically means that it will be a singleton
857 * acceptable for merging, so we can do all of this optimistically. But
858 * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
859 *
860 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
861 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
862 * is to return an anon_vma that is "complex" due to having gone through
863 * a fork).
864 *
865 * We also make sure that the two vma's are compatible (adjacent,
866 * and with the same memory policies). That's all stable, even with just
867 * a read lock on the mm_sem.
868 */
869static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
870{
871 if (anon_vma_compatible(a, b)) {
872 struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma);
873
874 if (anon_vma && list_is_singular(&old->anon_vma_chain))
875 return anon_vma;
876 }
877 return NULL;
878}
879
880/*
881 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
882 * neighbouring vmas for a suitable anon_vma, before it goes off
883 * to allocate a new anon_vma. It checks because a repetitive
884 * sequence of mprotects and faults may otherwise lead to distinct
885 * anon_vmas being allocated, preventing vma merge in subsequent
886 * mprotect.
887 */
888struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
889{
890 struct anon_vma *anon_vma;
891 struct vm_area_struct *near;
892
893 near = vma->vm_next;
894 if (!near)
895 goto try_prev;
896
897 anon_vma = reusable_anon_vma(near, vma, near);
898 if (anon_vma)
899 return anon_vma;
900try_prev:
901 near = vma->vm_prev;
902 if (!near)
903 goto none;
904
905 anon_vma = reusable_anon_vma(near, near, vma);
906 if (anon_vma)
907 return anon_vma;
908none:
909 /*
910 * There's no absolute need to look only at touching neighbours:
911 * we could search further afield for "compatible" anon_vmas.
912 * But it would probably just be a waste of time searching,
913 * or lead to too many vmas hanging off the same anon_vma.
914 * We're trying to allow mprotect remerging later on,
915 * not trying to minimize memory used for anon_vmas.
916 */
917 return NULL;
918}
919
920#ifdef CONFIG_PROC_FS
921void vm_stat_account(struct mm_struct *mm, unsigned long flags,
922 struct file *file, long pages)
923{
924 const unsigned long stack_flags
925 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
926
927 if (file) {
928 mm->shared_vm += pages;
929 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
930 mm->exec_vm += pages;
931 } else if (flags & stack_flags)
932 mm->stack_vm += pages;
933 if (flags & (VM_RESERVED|VM_IO))
934 mm->reserved_vm += pages;
935}
936#endif /* CONFIG_PROC_FS */
937
938/*
939 * The caller must hold down_write(¤t->mm->mmap_sem).
940 */
941
942unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
943 unsigned long len, unsigned long prot,
944 unsigned long flags, unsigned long pgoff)
945{
946 struct mm_struct * mm = current->mm;
947 struct inode *inode;
948 vm_flags_t vm_flags;
949 int error;
950 unsigned long reqprot = prot;
951
952 /*
953 * Does the application expect PROT_READ to imply PROT_EXEC?
954 *
955 * (the exception is when the underlying filesystem is noexec
956 * mounted, in which case we dont add PROT_EXEC.)
957 */
958 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
959 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
960 prot |= PROT_EXEC;
961
962 if (!len)
963 return -EINVAL;
964
965 if (!(flags & MAP_FIXED))
966 addr = round_hint_to_min(addr);
967
968 /* Careful about overflows.. */
969 len = PAGE_ALIGN(len);
970 if (!len)
971 return -ENOMEM;
972
973 /* offset overflow? */
974 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
975 return -EOVERFLOW;
976
977 /* Too many mappings? */
978 if (mm->map_count > sysctl_max_map_count)
979 return -ENOMEM;
980
981 /* Obtain the address to map to. we verify (or select) it and ensure
982 * that it represents a valid section of the address space.
983 */
984 addr = get_unmapped_area(file, addr, len, pgoff, flags);
985 if (addr & ~PAGE_MASK)
986 return addr;
987
988 /* Do simple checking here so the lower-level routines won't have
989 * to. we assume access permissions have been handled by the open
990 * of the memory object, so we don't do any here.
991 */
992 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
993 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
994
995 if (flags & MAP_LOCKED)
996 if (!can_do_mlock())
997 return -EPERM;
998
999 /* mlock MCL_FUTURE? */
1000 if (vm_flags & VM_LOCKED) {
1001 unsigned long locked, lock_limit;
1002 locked = len >> PAGE_SHIFT;
1003 locked += mm->locked_vm;
1004 lock_limit = rlimit(RLIMIT_MEMLOCK);
1005 lock_limit >>= PAGE_SHIFT;
1006 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1007 return -EAGAIN;
1008 }
1009
1010 inode = file ? file->f_path.dentry->d_inode : NULL;
1011
1012 if (file) {
1013 switch (flags & MAP_TYPE) {
1014 case MAP_SHARED:
1015 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1016 return -EACCES;
1017
1018 /*
1019 * Make sure we don't allow writing to an append-only
1020 * file..
1021 */
1022 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1023 return -EACCES;
1024
1025 /*
1026 * Make sure there are no mandatory locks on the file.
1027 */
1028 if (locks_verify_locked(inode))
1029 return -EAGAIN;
1030
1031 vm_flags |= VM_SHARED | VM_MAYSHARE;
1032 if (!(file->f_mode & FMODE_WRITE))
1033 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1034
1035 /* fall through */
1036 case MAP_PRIVATE:
1037 if (!(file->f_mode & FMODE_READ))
1038 return -EACCES;
1039 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1040 if (vm_flags & VM_EXEC)
1041 return -EPERM;
1042 vm_flags &= ~VM_MAYEXEC;
1043 }
1044
1045 if (!file->f_op || !file->f_op->mmap)
1046 return -ENODEV;
1047 break;
1048
1049 default:
1050 return -EINVAL;
1051 }
1052 } else {
1053 switch (flags & MAP_TYPE) {
1054 case MAP_SHARED:
1055 /*
1056 * Ignore pgoff.
1057 */
1058 pgoff = 0;
1059 vm_flags |= VM_SHARED | VM_MAYSHARE;
1060 break;
1061 case MAP_PRIVATE:
1062 /*
1063 * Set pgoff according to addr for anon_vma.
1064 */
1065 pgoff = addr >> PAGE_SHIFT;
1066 break;
1067 default:
1068 return -EINVAL;
1069 }
1070 }
1071
1072 error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1073 if (error)
1074 return error;
1075
1076 return mmap_region(file, addr, len, flags, vm_flags, pgoff);
1077}
1078EXPORT_SYMBOL(do_mmap_pgoff);
1079
1080SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1081 unsigned long, prot, unsigned long, flags,
1082 unsigned long, fd, unsigned long, pgoff)
1083{
1084 struct file *file = NULL;
1085 unsigned long retval = -EBADF;
1086
1087 if (!(flags & MAP_ANONYMOUS)) {
1088 audit_mmap_fd(fd, flags);
1089 if (unlikely(flags & MAP_HUGETLB))
1090 return -EINVAL;
1091 file = fget(fd);
1092 if (!file)
1093 goto out;
1094 } else if (flags & MAP_HUGETLB) {
1095 struct user_struct *user = NULL;
1096 /*
1097 * VM_NORESERVE is used because the reservations will be
1098 * taken when vm_ops->mmap() is called
1099 * A dummy user value is used because we are not locking
1100 * memory so no accounting is necessary
1101 */
1102 len = ALIGN(len, huge_page_size(&default_hstate));
1103 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, VM_NORESERVE,
1104 &user, HUGETLB_ANONHUGE_INODE);
1105 if (IS_ERR(file))
1106 return PTR_ERR(file);
1107 }
1108
1109 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1110
1111 down_write(¤t->mm->mmap_sem);
1112 retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1113 up_write(¤t->mm->mmap_sem);
1114
1115 if (file)
1116 fput(file);
1117out:
1118 return retval;
1119}
1120
1121#ifdef __ARCH_WANT_SYS_OLD_MMAP
1122struct mmap_arg_struct {
1123 unsigned long addr;
1124 unsigned long len;
1125 unsigned long prot;
1126 unsigned long flags;
1127 unsigned long fd;
1128 unsigned long offset;
1129};
1130
1131SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1132{
1133 struct mmap_arg_struct a;
1134
1135 if (copy_from_user(&a, arg, sizeof(a)))
1136 return -EFAULT;
1137 if (a.offset & ~PAGE_MASK)
1138 return -EINVAL;
1139
1140 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1141 a.offset >> PAGE_SHIFT);
1142}
1143#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1144
1145/*
1146 * Some shared mappigns will want the pages marked read-only
1147 * to track write events. If so, we'll downgrade vm_page_prot
1148 * to the private version (using protection_map[] without the
1149 * VM_SHARED bit).
1150 */
1151int vma_wants_writenotify(struct vm_area_struct *vma)
1152{
1153 vm_flags_t vm_flags = vma->vm_flags;
1154
1155 /* If it was private or non-writable, the write bit is already clear */
1156 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1157 return 0;
1158
1159 /* The backer wishes to know when pages are first written to? */
1160 if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1161 return 1;
1162
1163 /* The open routine did something to the protections already? */
1164 if (pgprot_val(vma->vm_page_prot) !=
1165 pgprot_val(vm_get_page_prot(vm_flags)))
1166 return 0;
1167
1168 /* Specialty mapping? */
1169 if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1170 return 0;
1171
1172 /* Can the mapping track the dirty pages? */
1173 return vma->vm_file && vma->vm_file->f_mapping &&
1174 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1175}
1176
1177/*
1178 * We account for memory if it's a private writeable mapping,
1179 * not hugepages and VM_NORESERVE wasn't set.
1180 */
1181static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1182{
1183 /*
1184 * hugetlb has its own accounting separate from the core VM
1185 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1186 */
1187 if (file && is_file_hugepages(file))
1188 return 0;
1189
1190 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1191}
1192
1193unsigned long mmap_region(struct file *file, unsigned long addr,
1194 unsigned long len, unsigned long flags,
1195 vm_flags_t vm_flags, unsigned long pgoff)
1196{
1197 struct mm_struct *mm = current->mm;
1198 struct vm_area_struct *vma, *prev;
1199 int correct_wcount = 0;
1200 int error;
1201 struct rb_node **rb_link, *rb_parent;
1202 unsigned long charged = 0;
1203 struct inode *inode = file ? file->f_path.dentry->d_inode : NULL;
1204
1205 /* Clear old maps */
1206 error = -ENOMEM;
1207munmap_back:
1208 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1209 if (vma && vma->vm_start < addr + len) {
1210 if (do_munmap(mm, addr, len))
1211 return -ENOMEM;
1212 goto munmap_back;
1213 }
1214
1215 /* Check against address space limit. */
1216 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1217 return -ENOMEM;
1218
1219 /*
1220 * Set 'VM_NORESERVE' if we should not account for the
1221 * memory use of this mapping.
1222 */
1223 if ((flags & MAP_NORESERVE)) {
1224 /* We honor MAP_NORESERVE if allowed to overcommit */
1225 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1226 vm_flags |= VM_NORESERVE;
1227
1228 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1229 if (file && is_file_hugepages(file))
1230 vm_flags |= VM_NORESERVE;
1231 }
1232
1233 /*
1234 * Private writable mapping: check memory availability
1235 */
1236 if (accountable_mapping(file, vm_flags)) {
1237 charged = len >> PAGE_SHIFT;
1238 if (security_vm_enough_memory(charged))
1239 return -ENOMEM;
1240 vm_flags |= VM_ACCOUNT;
1241 }
1242
1243 /*
1244 * Can we just expand an old mapping?
1245 */
1246 vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
1247 if (vma)
1248 goto out;
1249
1250 /*
1251 * Determine the object being mapped and call the appropriate
1252 * specific mapper. the address has already been validated, but
1253 * not unmapped, but the maps are removed from the list.
1254 */
1255 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1256 if (!vma) {
1257 error = -ENOMEM;
1258 goto unacct_error;
1259 }
1260
1261 vma->vm_mm = mm;
1262 vma->vm_start = addr;
1263 vma->vm_end = addr + len;
1264 vma->vm_flags = vm_flags;
1265 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1266 vma->vm_pgoff = pgoff;
1267 INIT_LIST_HEAD(&vma->anon_vma_chain);
1268
1269 if (file) {
1270 error = -EINVAL;
1271 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1272 goto free_vma;
1273 if (vm_flags & VM_DENYWRITE) {
1274 error = deny_write_access(file);
1275 if (error)
1276 goto free_vma;
1277 correct_wcount = 1;
1278 }
1279 vma->vm_file = file;
1280 get_file(file);
1281 error = file->f_op->mmap(file, vma);
1282 if (error)
1283 goto unmap_and_free_vma;
1284 if (vm_flags & VM_EXECUTABLE)
1285 added_exe_file_vma(mm);
1286
1287 /* Can addr have changed??
1288 *
1289 * Answer: Yes, several device drivers can do it in their
1290 * f_op->mmap method. -DaveM
1291 */
1292 addr = vma->vm_start;
1293 pgoff = vma->vm_pgoff;
1294 vm_flags = vma->vm_flags;
1295 } else if (vm_flags & VM_SHARED) {
1296 error = shmem_zero_setup(vma);
1297 if (error)
1298 goto free_vma;
1299 }
1300
1301 if (vma_wants_writenotify(vma)) {
1302 pgprot_t pprot = vma->vm_page_prot;
1303
1304 /* Can vma->vm_page_prot have changed??
1305 *
1306 * Answer: Yes, drivers may have changed it in their
1307 * f_op->mmap method.
1308 *
1309 * Ensures that vmas marked as uncached stay that way.
1310 */
1311 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1312 if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
1313 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
1314 }
1315
1316 vma_link(mm, vma, prev, rb_link, rb_parent);
1317 file = vma->vm_file;
1318
1319 /* Once vma denies write, undo our temporary denial count */
1320 if (correct_wcount)
1321 atomic_inc(&inode->i_writecount);
1322out:
1323 perf_event_mmap(vma);
1324
1325 mm->total_vm += len >> PAGE_SHIFT;
1326 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1327 if (vm_flags & VM_LOCKED) {
1328 if (!mlock_vma_pages_range(vma, addr, addr + len))
1329 mm->locked_vm += (len >> PAGE_SHIFT);
1330 } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1331 make_pages_present(addr, addr + len);
1332 return addr;
1333
1334unmap_and_free_vma:
1335 if (correct_wcount)
1336 atomic_inc(&inode->i_writecount);
1337 vma->vm_file = NULL;
1338 fput(file);
1339
1340 /* Undo any partial mapping done by a device driver. */
1341 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1342 charged = 0;
1343free_vma:
1344 kmem_cache_free(vm_area_cachep, vma);
1345unacct_error:
1346 if (charged)
1347 vm_unacct_memory(charged);
1348 return error;
1349}
1350
1351/* Get an address range which is currently unmapped.
1352 * For shmat() with addr=0.
1353 *
1354 * Ugly calling convention alert:
1355 * Return value with the low bits set means error value,
1356 * ie
1357 * if (ret & ~PAGE_MASK)
1358 * error = ret;
1359 *
1360 * This function "knows" that -ENOMEM has the bits set.
1361 */
1362#ifndef HAVE_ARCH_UNMAPPED_AREA
1363unsigned long
1364arch_get_unmapped_area(struct file *filp, unsigned long addr,
1365 unsigned long len, unsigned long pgoff, unsigned long flags)
1366{
1367 struct mm_struct *mm = current->mm;
1368 struct vm_area_struct *vma;
1369 unsigned long start_addr;
1370
1371 if (len > TASK_SIZE)
1372 return -ENOMEM;
1373
1374 if (flags & MAP_FIXED)
1375 return addr;
1376
1377 if (addr) {
1378 addr = PAGE_ALIGN(addr);
1379 vma = find_vma(mm, addr);
1380 if (TASK_SIZE - len >= addr &&
1381 (!vma || addr + len <= vma->vm_start))
1382 return addr;
1383 }
1384 if (len > mm->cached_hole_size) {
1385 start_addr = addr = mm->free_area_cache;
1386 } else {
1387 start_addr = addr = TASK_UNMAPPED_BASE;
1388 mm->cached_hole_size = 0;
1389 }
1390
1391full_search:
1392 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1393 /* At this point: (!vma || addr < vma->vm_end). */
1394 if (TASK_SIZE - len < addr) {
1395 /*
1396 * Start a new search - just in case we missed
1397 * some holes.
1398 */
1399 if (start_addr != TASK_UNMAPPED_BASE) {
1400 addr = TASK_UNMAPPED_BASE;
1401 start_addr = addr;
1402 mm->cached_hole_size = 0;
1403 goto full_search;
1404 }
1405 return -ENOMEM;
1406 }
1407 if (!vma || addr + len <= vma->vm_start) {
1408 /*
1409 * Remember the place where we stopped the search:
1410 */
1411 mm->free_area_cache = addr + len;
1412 return addr;
1413 }
1414 if (addr + mm->cached_hole_size < vma->vm_start)
1415 mm->cached_hole_size = vma->vm_start - addr;
1416 addr = vma->vm_end;
1417 }
1418}
1419#endif
1420
1421void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1422{
1423 /*
1424 * Is this a new hole at the lowest possible address?
1425 */
1426 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1427 mm->free_area_cache = addr;
1428 mm->cached_hole_size = ~0UL;
1429 }
1430}
1431
1432/*
1433 * This mmap-allocator allocates new areas top-down from below the
1434 * stack's low limit (the base):
1435 */
1436#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1437unsigned long
1438arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1439 const unsigned long len, const unsigned long pgoff,
1440 const unsigned long flags)
1441{
1442 struct vm_area_struct *vma;
1443 struct mm_struct *mm = current->mm;
1444 unsigned long addr = addr0;
1445
1446 /* requested length too big for entire address space */
1447 if (len > TASK_SIZE)
1448 return -ENOMEM;
1449
1450 if (flags & MAP_FIXED)
1451 return addr;
1452
1453 /* requesting a specific address */
1454 if (addr) {
1455 addr = PAGE_ALIGN(addr);
1456 vma = find_vma(mm, addr);
1457 if (TASK_SIZE - len >= addr &&
1458 (!vma || addr + len <= vma->vm_start))
1459 return addr;
1460 }
1461
1462 /* check if free_area_cache is useful for us */
1463 if (len <= mm->cached_hole_size) {
1464 mm->cached_hole_size = 0;
1465 mm->free_area_cache = mm->mmap_base;
1466 }
1467
1468 /* either no address requested or can't fit in requested address hole */
1469 addr = mm->free_area_cache;
1470
1471 /* make sure it can fit in the remaining address space */
1472 if (addr > len) {
1473 vma = find_vma(mm, addr-len);
1474 if (!vma || addr <= vma->vm_start)
1475 /* remember the address as a hint for next time */
1476 return (mm->free_area_cache = addr-len);
1477 }
1478
1479 if (mm->mmap_base < len)
1480 goto bottomup;
1481
1482 addr = mm->mmap_base-len;
1483
1484 do {
1485 /*
1486 * Lookup failure means no vma is above this address,
1487 * else if new region fits below vma->vm_start,
1488 * return with success:
1489 */
1490 vma = find_vma(mm, addr);
1491 if (!vma || addr+len <= vma->vm_start)
1492 /* remember the address as a hint for next time */
1493 return (mm->free_area_cache = addr);
1494
1495 /* remember the largest hole we saw so far */
1496 if (addr + mm->cached_hole_size < vma->vm_start)
1497 mm->cached_hole_size = vma->vm_start - addr;
1498
1499 /* try just below the current vma->vm_start */
1500 addr = vma->vm_start-len;
1501 } while (len < vma->vm_start);
1502
1503bottomup:
1504 /*
1505 * A failed mmap() very likely causes application failure,
1506 * so fall back to the bottom-up function here. This scenario
1507 * can happen with large stack limits and large mmap()
1508 * allocations.
1509 */
1510 mm->cached_hole_size = ~0UL;
1511 mm->free_area_cache = TASK_UNMAPPED_BASE;
1512 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1513 /*
1514 * Restore the topdown base:
1515 */
1516 mm->free_area_cache = mm->mmap_base;
1517 mm->cached_hole_size = ~0UL;
1518
1519 return addr;
1520}
1521#endif
1522
1523void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1524{
1525 /*
1526 * Is this a new hole at the highest possible address?
1527 */
1528 if (addr > mm->free_area_cache)
1529 mm->free_area_cache = addr;
1530
1531 /* dont allow allocations above current base */
1532 if (mm->free_area_cache > mm->mmap_base)
1533 mm->free_area_cache = mm->mmap_base;
1534}
1535
1536unsigned long
1537get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1538 unsigned long pgoff, unsigned long flags)
1539{
1540 unsigned long (*get_area)(struct file *, unsigned long,
1541 unsigned long, unsigned long, unsigned long);
1542
1543 unsigned long error = arch_mmap_check(addr, len, flags);
1544 if (error)
1545 return error;
1546
1547 /* Careful about overflows.. */
1548 if (len > TASK_SIZE)
1549 return -ENOMEM;
1550
1551 get_area = current->mm->get_unmapped_area;
1552 if (file && file->f_op && file->f_op->get_unmapped_area)
1553 get_area = file->f_op->get_unmapped_area;
1554 addr = get_area(file, addr, len, pgoff, flags);
1555 if (IS_ERR_VALUE(addr))
1556 return addr;
1557
1558 if (addr > TASK_SIZE - len)
1559 return -ENOMEM;
1560 if (addr & ~PAGE_MASK)
1561 return -EINVAL;
1562
1563 return arch_rebalance_pgtables(addr, len);
1564}
1565
1566EXPORT_SYMBOL(get_unmapped_area);
1567
1568/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1569struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1570{
1571 struct vm_area_struct *vma = NULL;
1572
1573 if (mm) {
1574 /* Check the cache first. */
1575 /* (Cache hit rate is typically around 35%.) */
1576 vma = mm->mmap_cache;
1577 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1578 struct rb_node * rb_node;
1579
1580 rb_node = mm->mm_rb.rb_node;
1581 vma = NULL;
1582
1583 while (rb_node) {
1584 struct vm_area_struct * vma_tmp;
1585
1586 vma_tmp = rb_entry(rb_node,
1587 struct vm_area_struct, vm_rb);
1588
1589 if (vma_tmp->vm_end > addr) {
1590 vma = vma_tmp;
1591 if (vma_tmp->vm_start <= addr)
1592 break;
1593 rb_node = rb_node->rb_left;
1594 } else
1595 rb_node = rb_node->rb_right;
1596 }
1597 if (vma)
1598 mm->mmap_cache = vma;
1599 }
1600 }
1601 return vma;
1602}
1603
1604EXPORT_SYMBOL(find_vma);
1605
1606/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1607struct vm_area_struct *
1608find_vma_prev(struct mm_struct *mm, unsigned long addr,
1609 struct vm_area_struct **pprev)
1610{
1611 struct vm_area_struct *vma = NULL, *prev = NULL;
1612 struct rb_node *rb_node;
1613 if (!mm)
1614 goto out;
1615
1616 /* Guard against addr being lower than the first VMA */
1617 vma = mm->mmap;
1618
1619 /* Go through the RB tree quickly. */
1620 rb_node = mm->mm_rb.rb_node;
1621
1622 while (rb_node) {
1623 struct vm_area_struct *vma_tmp;
1624 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1625
1626 if (addr < vma_tmp->vm_end) {
1627 rb_node = rb_node->rb_left;
1628 } else {
1629 prev = vma_tmp;
1630 if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1631 break;
1632 rb_node = rb_node->rb_right;
1633 }
1634 }
1635
1636out:
1637 *pprev = prev;
1638 return prev ? prev->vm_next : vma;
1639}
1640
1641/*
1642 * Verify that the stack growth is acceptable and
1643 * update accounting. This is shared with both the
1644 * grow-up and grow-down cases.
1645 */
1646static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
1647{
1648 struct mm_struct *mm = vma->vm_mm;
1649 struct rlimit *rlim = current->signal->rlim;
1650 unsigned long new_start;
1651
1652 /* address space limit tests */
1653 if (!may_expand_vm(mm, grow))
1654 return -ENOMEM;
1655
1656 /* Stack limit test */
1657 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
1658 return -ENOMEM;
1659
1660 /* mlock limit tests */
1661 if (vma->vm_flags & VM_LOCKED) {
1662 unsigned long locked;
1663 unsigned long limit;
1664 locked = mm->locked_vm + grow;
1665 limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
1666 limit >>= PAGE_SHIFT;
1667 if (locked > limit && !capable(CAP_IPC_LOCK))
1668 return -ENOMEM;
1669 }
1670
1671 /* Check to ensure the stack will not grow into a hugetlb-only region */
1672 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1673 vma->vm_end - size;
1674 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1675 return -EFAULT;
1676
1677 /*
1678 * Overcommit.. This must be the final test, as it will
1679 * update security statistics.
1680 */
1681 if (security_vm_enough_memory_mm(mm, grow))
1682 return -ENOMEM;
1683
1684 /* Ok, everything looks good - let it rip */
1685 mm->total_vm += grow;
1686 if (vma->vm_flags & VM_LOCKED)
1687 mm->locked_vm += grow;
1688 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1689 return 0;
1690}
1691
1692#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1693/*
1694 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1695 * vma is the last one with address > vma->vm_end. Have to extend vma.
1696 */
1697int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1698{
1699 int error;
1700
1701 if (!(vma->vm_flags & VM_GROWSUP))
1702 return -EFAULT;
1703
1704 /*
1705 * We must make sure the anon_vma is allocated
1706 * so that the anon_vma locking is not a noop.
1707 */
1708 if (unlikely(anon_vma_prepare(vma)))
1709 return -ENOMEM;
1710 vma_lock_anon_vma(vma);
1711
1712 /*
1713 * vma->vm_start/vm_end cannot change under us because the caller
1714 * is required to hold the mmap_sem in read mode. We need the
1715 * anon_vma lock to serialize against concurrent expand_stacks.
1716 * Also guard against wrapping around to address 0.
1717 */
1718 if (address < PAGE_ALIGN(address+4))
1719 address = PAGE_ALIGN(address+4);
1720 else {
1721 vma_unlock_anon_vma(vma);
1722 return -ENOMEM;
1723 }
1724 error = 0;
1725
1726 /* Somebody else might have raced and expanded it already */
1727 if (address > vma->vm_end) {
1728 unsigned long size, grow;
1729
1730 size = address - vma->vm_start;
1731 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1732
1733 error = -ENOMEM;
1734 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
1735 error = acct_stack_growth(vma, size, grow);
1736 if (!error) {
1737 vma->vm_end = address;
1738 perf_event_mmap(vma);
1739 }
1740 }
1741 }
1742 vma_unlock_anon_vma(vma);
1743 khugepaged_enter_vma_merge(vma);
1744 return error;
1745}
1746#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1747
1748/*
1749 * vma is the first one with address < vma->vm_start. Have to extend vma.
1750 */
1751int expand_downwards(struct vm_area_struct *vma,
1752 unsigned long address)
1753{
1754 int error;
1755
1756 /*
1757 * We must make sure the anon_vma is allocated
1758 * so that the anon_vma locking is not a noop.
1759 */
1760 if (unlikely(anon_vma_prepare(vma)))
1761 return -ENOMEM;
1762
1763 address &= PAGE_MASK;
1764 error = security_file_mmap(NULL, 0, 0, 0, address, 1);
1765 if (error)
1766 return error;
1767
1768 vma_lock_anon_vma(vma);
1769
1770 /*
1771 * vma->vm_start/vm_end cannot change under us because the caller
1772 * is required to hold the mmap_sem in read mode. We need the
1773 * anon_vma lock to serialize against concurrent expand_stacks.
1774 */
1775
1776 /* Somebody else might have raced and expanded it already */
1777 if (address < vma->vm_start) {
1778 unsigned long size, grow;
1779
1780 size = vma->vm_end - address;
1781 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1782
1783 error = -ENOMEM;
1784 if (grow <= vma->vm_pgoff) {
1785 error = acct_stack_growth(vma, size, grow);
1786 if (!error) {
1787 vma->vm_start = address;
1788 vma->vm_pgoff -= grow;
1789 perf_event_mmap(vma);
1790 }
1791 }
1792 }
1793 vma_unlock_anon_vma(vma);
1794 khugepaged_enter_vma_merge(vma);
1795 return error;
1796}
1797
1798#ifdef CONFIG_STACK_GROWSUP
1799int expand_stack(struct vm_area_struct *vma, unsigned long address)
1800{
1801 return expand_upwards(vma, address);
1802}
1803
1804struct vm_area_struct *
1805find_extend_vma(struct mm_struct *mm, unsigned long addr)
1806{
1807 struct vm_area_struct *vma, *prev;
1808
1809 addr &= PAGE_MASK;
1810 vma = find_vma_prev(mm, addr, &prev);
1811 if (vma && (vma->vm_start <= addr))
1812 return vma;
1813 if (!prev || expand_stack(prev, addr))
1814 return NULL;
1815 if (prev->vm_flags & VM_LOCKED) {
1816 mlock_vma_pages_range(prev, addr, prev->vm_end);
1817 }
1818 return prev;
1819}
1820#else
1821int expand_stack(struct vm_area_struct *vma, unsigned long address)
1822{
1823 return expand_downwards(vma, address);
1824}
1825
1826struct vm_area_struct *
1827find_extend_vma(struct mm_struct * mm, unsigned long addr)
1828{
1829 struct vm_area_struct * vma;
1830 unsigned long start;
1831
1832 addr &= PAGE_MASK;
1833 vma = find_vma(mm,addr);
1834 if (!vma)
1835 return NULL;
1836 if (vma->vm_start <= addr)
1837 return vma;
1838 if (!(vma->vm_flags & VM_GROWSDOWN))
1839 return NULL;
1840 start = vma->vm_start;
1841 if (expand_stack(vma, addr))
1842 return NULL;
1843 if (vma->vm_flags & VM_LOCKED) {
1844 mlock_vma_pages_range(vma, addr, start);
1845 }
1846 return vma;
1847}
1848#endif
1849
1850/*
1851 * Ok - we have the memory areas we should free on the vma list,
1852 * so release them, and do the vma updates.
1853 *
1854 * Called with the mm semaphore held.
1855 */
1856static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1857{
1858 /* Update high watermark before we lower total_vm */
1859 update_hiwater_vm(mm);
1860 do {
1861 long nrpages = vma_pages(vma);
1862
1863 mm->total_vm -= nrpages;
1864 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1865 vma = remove_vma(vma);
1866 } while (vma);
1867 validate_mm(mm);
1868}
1869
1870/*
1871 * Get rid of page table information in the indicated region.
1872 *
1873 * Called with the mm semaphore held.
1874 */
1875static void unmap_region(struct mm_struct *mm,
1876 struct vm_area_struct *vma, struct vm_area_struct *prev,
1877 unsigned long start, unsigned long end)
1878{
1879 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1880 struct mmu_gather tlb;
1881 unsigned long nr_accounted = 0;
1882
1883 lru_add_drain();
1884 tlb_gather_mmu(&tlb, mm, 0);
1885 update_hiwater_rss(mm);
1886 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1887 vm_unacct_memory(nr_accounted);
1888 free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
1889 next ? next->vm_start : 0);
1890 tlb_finish_mmu(&tlb, start, end);
1891}
1892
1893/*
1894 * Create a list of vma's touched by the unmap, removing them from the mm's
1895 * vma list as we go..
1896 */
1897static void
1898detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1899 struct vm_area_struct *prev, unsigned long end)
1900{
1901 struct vm_area_struct **insertion_point;
1902 struct vm_area_struct *tail_vma = NULL;
1903 unsigned long addr;
1904
1905 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1906 vma->vm_prev = NULL;
1907 do {
1908 rb_erase(&vma->vm_rb, &mm->mm_rb);
1909 mm->map_count--;
1910 tail_vma = vma;
1911 vma = vma->vm_next;
1912 } while (vma && vma->vm_start < end);
1913 *insertion_point = vma;
1914 if (vma)
1915 vma->vm_prev = prev;
1916 tail_vma->vm_next = NULL;
1917 if (mm->unmap_area == arch_unmap_area)
1918 addr = prev ? prev->vm_end : mm->mmap_base;
1919 else
1920 addr = vma ? vma->vm_start : mm->mmap_base;
1921 mm->unmap_area(mm, addr);
1922 mm->mmap_cache = NULL; /* Kill the cache. */
1923}
1924
1925/*
1926 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
1927 * munmap path where it doesn't make sense to fail.
1928 */
1929static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1930 unsigned long addr, int new_below)
1931{
1932 struct mempolicy *pol;
1933 struct vm_area_struct *new;
1934 int err = -ENOMEM;
1935
1936 if (is_vm_hugetlb_page(vma) && (addr &
1937 ~(huge_page_mask(hstate_vma(vma)))))
1938 return -EINVAL;
1939
1940 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1941 if (!new)
1942 goto out_err;
1943
1944 /* most fields are the same, copy all, and then fixup */
1945 *new = *vma;
1946
1947 INIT_LIST_HEAD(&new->anon_vma_chain);
1948
1949 if (new_below)
1950 new->vm_end = addr;
1951 else {
1952 new->vm_start = addr;
1953 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1954 }
1955
1956 pol = mpol_dup(vma_policy(vma));
1957 if (IS_ERR(pol)) {
1958 err = PTR_ERR(pol);
1959 goto out_free_vma;
1960 }
1961 vma_set_policy(new, pol);
1962
1963 if (anon_vma_clone(new, vma))
1964 goto out_free_mpol;
1965
1966 if (new->vm_file) {
1967 get_file(new->vm_file);
1968 if (vma->vm_flags & VM_EXECUTABLE)
1969 added_exe_file_vma(mm);
1970 }
1971
1972 if (new->vm_ops && new->vm_ops->open)
1973 new->vm_ops->open(new);
1974
1975 if (new_below)
1976 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1977 ((addr - new->vm_start) >> PAGE_SHIFT), new);
1978 else
1979 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
1980
1981 /* Success. */
1982 if (!err)
1983 return 0;
1984
1985 /* Clean everything up if vma_adjust failed. */
1986 if (new->vm_ops && new->vm_ops->close)
1987 new->vm_ops->close(new);
1988 if (new->vm_file) {
1989 if (vma->vm_flags & VM_EXECUTABLE)
1990 removed_exe_file_vma(mm);
1991 fput(new->vm_file);
1992 }
1993 unlink_anon_vmas(new);
1994 out_free_mpol:
1995 mpol_put(pol);
1996 out_free_vma:
1997 kmem_cache_free(vm_area_cachep, new);
1998 out_err:
1999 return err;
2000}
2001
2002/*
2003 * Split a vma into two pieces at address 'addr', a new vma is allocated
2004 * either for the first part or the tail.
2005 */
2006int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2007 unsigned long addr, int new_below)
2008{
2009 if (mm->map_count >= sysctl_max_map_count)
2010 return -ENOMEM;
2011
2012 return __split_vma(mm, vma, addr, new_below);
2013}
2014
2015/* Munmap is split into 2 main parts -- this part which finds
2016 * what needs doing, and the areas themselves, which do the
2017 * work. This now handles partial unmappings.
2018 * Jeremy Fitzhardinge <jeremy@goop.org>
2019 */
2020int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2021{
2022 unsigned long end;
2023 struct vm_area_struct *vma, *prev, *last;
2024
2025 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
2026 return -EINVAL;
2027
2028 if ((len = PAGE_ALIGN(len)) == 0)
2029 return -EINVAL;
2030
2031 /* Find the first overlapping VMA */
2032 vma = find_vma(mm, start);
2033 if (!vma)
2034 return 0;
2035 prev = vma->vm_prev;
2036 /* we have start < vma->vm_end */
2037
2038 /* if it doesn't overlap, we have nothing.. */
2039 end = start + len;
2040 if (vma->vm_start >= end)
2041 return 0;
2042
2043 /*
2044 * If we need to split any vma, do it now to save pain later.
2045 *
2046 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2047 * unmapped vm_area_struct will remain in use: so lower split_vma
2048 * places tmp vma above, and higher split_vma places tmp vma below.
2049 */
2050 if (start > vma->vm_start) {
2051 int error;
2052
2053 /*
2054 * Make sure that map_count on return from munmap() will
2055 * not exceed its limit; but let map_count go just above
2056 * its limit temporarily, to help free resources as expected.
2057 */
2058 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2059 return -ENOMEM;
2060
2061 error = __split_vma(mm, vma, start, 0);
2062 if (error)
2063 return error;
2064 prev = vma;
2065 }
2066
2067 /* Does it split the last one? */
2068 last = find_vma(mm, end);
2069 if (last && end > last->vm_start) {
2070 int error = __split_vma(mm, last, end, 1);
2071 if (error)
2072 return error;
2073 }
2074 vma = prev? prev->vm_next: mm->mmap;
2075
2076 /*
2077 * unlock any mlock()ed ranges before detaching vmas
2078 */
2079 if (mm->locked_vm) {
2080 struct vm_area_struct *tmp = vma;
2081 while (tmp && tmp->vm_start < end) {
2082 if (tmp->vm_flags & VM_LOCKED) {
2083 mm->locked_vm -= vma_pages(tmp);
2084 munlock_vma_pages_all(tmp);
2085 }
2086 tmp = tmp->vm_next;
2087 }
2088 }
2089
2090 /*
2091 * Remove the vma's, and unmap the actual pages
2092 */
2093 detach_vmas_to_be_unmapped(mm, vma, prev, end);
2094 unmap_region(mm, vma, prev, start, end);
2095
2096 /* Fix up all other VM information */
2097 remove_vma_list(mm, vma);
2098
2099 return 0;
2100}
2101
2102EXPORT_SYMBOL(do_munmap);
2103
2104SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2105{
2106 int ret;
2107 struct mm_struct *mm = current->mm;
2108
2109 profile_munmap(addr);
2110
2111 down_write(&mm->mmap_sem);
2112 ret = do_munmap(mm, addr, len);
2113 up_write(&mm->mmap_sem);
2114 return ret;
2115}
2116
2117static inline void verify_mm_writelocked(struct mm_struct *mm)
2118{
2119#ifdef CONFIG_DEBUG_VM
2120 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2121 WARN_ON(1);
2122 up_read(&mm->mmap_sem);
2123 }
2124#endif
2125}
2126
2127/*
2128 * this is really a simplified "do_mmap". it only handles
2129 * anonymous maps. eventually we may be able to do some
2130 * brk-specific accounting here.
2131 */
2132unsigned long do_brk(unsigned long addr, unsigned long len)
2133{
2134 struct mm_struct * mm = current->mm;
2135 struct vm_area_struct * vma, * prev;
2136 unsigned long flags;
2137 struct rb_node ** rb_link, * rb_parent;
2138 pgoff_t pgoff = addr >> PAGE_SHIFT;
2139 int error;
2140
2141 len = PAGE_ALIGN(len);
2142 if (!len)
2143 return addr;
2144
2145 error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
2146 if (error)
2147 return error;
2148
2149 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2150
2151 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2152 if (error & ~PAGE_MASK)
2153 return error;
2154
2155 /*
2156 * mlock MCL_FUTURE?
2157 */
2158 if (mm->def_flags & VM_LOCKED) {
2159 unsigned long locked, lock_limit;
2160 locked = len >> PAGE_SHIFT;
2161 locked += mm->locked_vm;
2162 lock_limit = rlimit(RLIMIT_MEMLOCK);
2163 lock_limit >>= PAGE_SHIFT;
2164 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
2165 return -EAGAIN;
2166 }
2167
2168 /*
2169 * mm->mmap_sem is required to protect against another thread
2170 * changing the mappings in case we sleep.
2171 */
2172 verify_mm_writelocked(mm);
2173
2174 /*
2175 * Clear old maps. this also does some error checking for us
2176 */
2177 munmap_back:
2178 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2179 if (vma && vma->vm_start < addr + len) {
2180 if (do_munmap(mm, addr, len))
2181 return -ENOMEM;
2182 goto munmap_back;
2183 }
2184
2185 /* Check against address space limits *after* clearing old maps... */
2186 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2187 return -ENOMEM;
2188
2189 if (mm->map_count > sysctl_max_map_count)
2190 return -ENOMEM;
2191
2192 if (security_vm_enough_memory(len >> PAGE_SHIFT))
2193 return -ENOMEM;
2194
2195 /* Can we just expand an old private anonymous mapping? */
2196 vma = vma_merge(mm, prev, addr, addr + len, flags,
2197 NULL, NULL, pgoff, NULL);
2198 if (vma)
2199 goto out;
2200
2201 /*
2202 * create a vma struct for an anonymous mapping
2203 */
2204 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2205 if (!vma) {
2206 vm_unacct_memory(len >> PAGE_SHIFT);
2207 return -ENOMEM;
2208 }
2209
2210 INIT_LIST_HEAD(&vma->anon_vma_chain);
2211 vma->vm_mm = mm;
2212 vma->vm_start = addr;
2213 vma->vm_end = addr + len;
2214 vma->vm_pgoff = pgoff;
2215 vma->vm_flags = flags;
2216 vma->vm_page_prot = vm_get_page_prot(flags);
2217 vma_link(mm, vma, prev, rb_link, rb_parent);
2218out:
2219 perf_event_mmap(vma);
2220 mm->total_vm += len >> PAGE_SHIFT;
2221 if (flags & VM_LOCKED) {
2222 if (!mlock_vma_pages_range(vma, addr, addr + len))
2223 mm->locked_vm += (len >> PAGE_SHIFT);
2224 }
2225 return addr;
2226}
2227
2228EXPORT_SYMBOL(do_brk);
2229
2230/* Release all mmaps. */
2231void exit_mmap(struct mm_struct *mm)
2232{
2233 struct mmu_gather tlb;
2234 struct vm_area_struct *vma;
2235 unsigned long nr_accounted = 0;
2236 unsigned long end;
2237
2238 /* mm's last user has gone, and its about to be pulled down */
2239 mmu_notifier_release(mm);
2240
2241 if (mm->locked_vm) {
2242 vma = mm->mmap;
2243 while (vma) {
2244 if (vma->vm_flags & VM_LOCKED)
2245 munlock_vma_pages_all(vma);
2246 vma = vma->vm_next;
2247 }
2248 }
2249
2250 arch_exit_mmap(mm);
2251
2252 vma = mm->mmap;
2253 if (!vma) /* Can happen if dup_mmap() received an OOM */
2254 return;
2255
2256 lru_add_drain();
2257 flush_cache_mm(mm);
2258 tlb_gather_mmu(&tlb, mm, 1);
2259 /* update_hiwater_rss(mm) here? but nobody should be looking */
2260 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2261 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
2262 vm_unacct_memory(nr_accounted);
2263
2264 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
2265 tlb_finish_mmu(&tlb, 0, end);
2266
2267 /*
2268 * Walk the list again, actually closing and freeing it,
2269 * with preemption enabled, without holding any MM locks.
2270 */
2271 while (vma)
2272 vma = remove_vma(vma);
2273
2274 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2275}
2276
2277/* Insert vm structure into process list sorted by address
2278 * and into the inode's i_mmap tree. If vm_file is non-NULL
2279 * then i_mmap_mutex is taken here.
2280 */
2281int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2282{
2283 struct vm_area_struct * __vma, * prev;
2284 struct rb_node ** rb_link, * rb_parent;
2285
2286 /*
2287 * The vm_pgoff of a purely anonymous vma should be irrelevant
2288 * until its first write fault, when page's anon_vma and index
2289 * are set. But now set the vm_pgoff it will almost certainly
2290 * end up with (unless mremap moves it elsewhere before that
2291 * first wfault), so /proc/pid/maps tells a consistent story.
2292 *
2293 * By setting it to reflect the virtual start address of the
2294 * vma, merges and splits can happen in a seamless way, just
2295 * using the existing file pgoff checks and manipulations.
2296 * Similarly in do_mmap_pgoff and in do_brk.
2297 */
2298 if (!vma->vm_file) {
2299 BUG_ON(vma->anon_vma);
2300 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2301 }
2302 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2303 if (__vma && __vma->vm_start < vma->vm_end)
2304 return -ENOMEM;
2305 if ((vma->vm_flags & VM_ACCOUNT) &&
2306 security_vm_enough_memory_mm(mm, vma_pages(vma)))
2307 return -ENOMEM;
2308 vma_link(mm, vma, prev, rb_link, rb_parent);
2309 return 0;
2310}
2311
2312/*
2313 * Copy the vma structure to a new location in the same mm,
2314 * prior to moving page table entries, to effect an mremap move.
2315 */
2316struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2317 unsigned long addr, unsigned long len, pgoff_t pgoff)
2318{
2319 struct vm_area_struct *vma = *vmap;
2320 unsigned long vma_start = vma->vm_start;
2321 struct mm_struct *mm = vma->vm_mm;
2322 struct vm_area_struct *new_vma, *prev;
2323 struct rb_node **rb_link, *rb_parent;
2324 struct mempolicy *pol;
2325
2326 /*
2327 * If anonymous vma has not yet been faulted, update new pgoff
2328 * to match new location, to increase its chance of merging.
2329 */
2330 if (!vma->vm_file && !vma->anon_vma)
2331 pgoff = addr >> PAGE_SHIFT;
2332
2333 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2334 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2335 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2336 if (new_vma) {
2337 /*
2338 * Source vma may have been merged into new_vma
2339 */
2340 if (vma_start >= new_vma->vm_start &&
2341 vma_start < new_vma->vm_end)
2342 *vmap = new_vma;
2343 } else {
2344 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2345 if (new_vma) {
2346 *new_vma = *vma;
2347 pol = mpol_dup(vma_policy(vma));
2348 if (IS_ERR(pol))
2349 goto out_free_vma;
2350 INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2351 if (anon_vma_clone(new_vma, vma))
2352 goto out_free_mempol;
2353 vma_set_policy(new_vma, pol);
2354 new_vma->vm_start = addr;
2355 new_vma->vm_end = addr + len;
2356 new_vma->vm_pgoff = pgoff;
2357 if (new_vma->vm_file) {
2358 get_file(new_vma->vm_file);
2359 if (vma->vm_flags & VM_EXECUTABLE)
2360 added_exe_file_vma(mm);
2361 }
2362 if (new_vma->vm_ops && new_vma->vm_ops->open)
2363 new_vma->vm_ops->open(new_vma);
2364 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2365 }
2366 }
2367 return new_vma;
2368
2369 out_free_mempol:
2370 mpol_put(pol);
2371 out_free_vma:
2372 kmem_cache_free(vm_area_cachep, new_vma);
2373 return NULL;
2374}
2375
2376/*
2377 * Return true if the calling process may expand its vm space by the passed
2378 * number of pages
2379 */
2380int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2381{
2382 unsigned long cur = mm->total_vm; /* pages */
2383 unsigned long lim;
2384
2385 lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
2386
2387 if (cur + npages > lim)
2388 return 0;
2389 return 1;
2390}
2391
2392
2393static int special_mapping_fault(struct vm_area_struct *vma,
2394 struct vm_fault *vmf)
2395{
2396 pgoff_t pgoff;
2397 struct page **pages;
2398
2399 /*
2400 * special mappings have no vm_file, and in that case, the mm
2401 * uses vm_pgoff internally. So we have to subtract it from here.
2402 * We are allowed to do this because we are the mm; do not copy
2403 * this code into drivers!
2404 */
2405 pgoff = vmf->pgoff - vma->vm_pgoff;
2406
2407 for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2408 pgoff--;
2409
2410 if (*pages) {
2411 struct page *page = *pages;
2412 get_page(page);
2413 vmf->page = page;
2414 return 0;
2415 }
2416
2417 return VM_FAULT_SIGBUS;
2418}
2419
2420/*
2421 * Having a close hook prevents vma merging regardless of flags.
2422 */
2423static void special_mapping_close(struct vm_area_struct *vma)
2424{
2425}
2426
2427static const struct vm_operations_struct special_mapping_vmops = {
2428 .close = special_mapping_close,
2429 .fault = special_mapping_fault,
2430};
2431
2432/*
2433 * Called with mm->mmap_sem held for writing.
2434 * Insert a new vma covering the given region, with the given flags.
2435 * Its pages are supplied by the given array of struct page *.
2436 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2437 * The region past the last page supplied will always produce SIGBUS.
2438 * The array pointer and the pages it points to are assumed to stay alive
2439 * for as long as this mapping might exist.
2440 */
2441int install_special_mapping(struct mm_struct *mm,
2442 unsigned long addr, unsigned long len,
2443 unsigned long vm_flags, struct page **pages)
2444{
2445 int ret;
2446 struct vm_area_struct *vma;
2447
2448 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2449 if (unlikely(vma == NULL))
2450 return -ENOMEM;
2451
2452 INIT_LIST_HEAD(&vma->anon_vma_chain);
2453 vma->vm_mm = mm;
2454 vma->vm_start = addr;
2455 vma->vm_end = addr + len;
2456
2457 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2458 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2459
2460 vma->vm_ops = &special_mapping_vmops;
2461 vma->vm_private_data = pages;
2462
2463 ret = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
2464 if (ret)
2465 goto out;
2466
2467 ret = insert_vm_struct(mm, vma);
2468 if (ret)
2469 goto out;
2470
2471 mm->total_vm += len >> PAGE_SHIFT;
2472
2473 perf_event_mmap(vma);
2474
2475 return 0;
2476
2477out:
2478 kmem_cache_free(vm_area_cachep, vma);
2479 return ret;
2480}
2481
2482static DEFINE_MUTEX(mm_all_locks_mutex);
2483
2484static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2485{
2486 if (!test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2487 /*
2488 * The LSB of head.next can't change from under us
2489 * because we hold the mm_all_locks_mutex.
2490 */
2491 mutex_lock_nest_lock(&anon_vma->root->mutex, &mm->mmap_sem);
2492 /*
2493 * We can safely modify head.next after taking the
2494 * anon_vma->root->mutex. If some other vma in this mm shares
2495 * the same anon_vma we won't take it again.
2496 *
2497 * No need of atomic instructions here, head.next
2498 * can't change from under us thanks to the
2499 * anon_vma->root->mutex.
2500 */
2501 if (__test_and_set_bit(0, (unsigned long *)
2502 &anon_vma->root->head.next))
2503 BUG();
2504 }
2505}
2506
2507static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2508{
2509 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2510 /*
2511 * AS_MM_ALL_LOCKS can't change from under us because
2512 * we hold the mm_all_locks_mutex.
2513 *
2514 * Operations on ->flags have to be atomic because
2515 * even if AS_MM_ALL_LOCKS is stable thanks to the
2516 * mm_all_locks_mutex, there may be other cpus
2517 * changing other bitflags in parallel to us.
2518 */
2519 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
2520 BUG();
2521 mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem);
2522 }
2523}
2524
2525/*
2526 * This operation locks against the VM for all pte/vma/mm related
2527 * operations that could ever happen on a certain mm. This includes
2528 * vmtruncate, try_to_unmap, and all page faults.
2529 *
2530 * The caller must take the mmap_sem in write mode before calling
2531 * mm_take_all_locks(). The caller isn't allowed to release the
2532 * mmap_sem until mm_drop_all_locks() returns.
2533 *
2534 * mmap_sem in write mode is required in order to block all operations
2535 * that could modify pagetables and free pages without need of
2536 * altering the vma layout (for example populate_range() with
2537 * nonlinear vmas). It's also needed in write mode to avoid new
2538 * anon_vmas to be associated with existing vmas.
2539 *
2540 * A single task can't take more than one mm_take_all_locks() in a row
2541 * or it would deadlock.
2542 *
2543 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
2544 * mapping->flags avoid to take the same lock twice, if more than one
2545 * vma in this mm is backed by the same anon_vma or address_space.
2546 *
2547 * We can take all the locks in random order because the VM code
2548 * taking i_mmap_mutex or anon_vma->mutex outside the mmap_sem never
2549 * takes more than one of them in a row. Secondly we're protected
2550 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2551 *
2552 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2553 * that may have to take thousand of locks.
2554 *
2555 * mm_take_all_locks() can fail if it's interrupted by signals.
2556 */
2557int mm_take_all_locks(struct mm_struct *mm)
2558{
2559 struct vm_area_struct *vma;
2560 struct anon_vma_chain *avc;
2561 int ret = -EINTR;
2562
2563 BUG_ON(down_read_trylock(&mm->mmap_sem));
2564
2565 mutex_lock(&mm_all_locks_mutex);
2566
2567 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2568 if (signal_pending(current))
2569 goto out_unlock;
2570 if (vma->vm_file && vma->vm_file->f_mapping)
2571 vm_lock_mapping(mm, vma->vm_file->f_mapping);
2572 }
2573
2574 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2575 if (signal_pending(current))
2576 goto out_unlock;
2577 if (vma->anon_vma)
2578 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2579 vm_lock_anon_vma(mm, avc->anon_vma);
2580 }
2581
2582 ret = 0;
2583
2584out_unlock:
2585 if (ret)
2586 mm_drop_all_locks(mm);
2587
2588 return ret;
2589}
2590
2591static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
2592{
2593 if (test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2594 /*
2595 * The LSB of head.next can't change to 0 from under
2596 * us because we hold the mm_all_locks_mutex.
2597 *
2598 * We must however clear the bitflag before unlocking
2599 * the vma so the users using the anon_vma->head will
2600 * never see our bitflag.
2601 *
2602 * No need of atomic instructions here, head.next
2603 * can't change from under us until we release the
2604 * anon_vma->root->mutex.
2605 */
2606 if (!__test_and_clear_bit(0, (unsigned long *)
2607 &anon_vma->root->head.next))
2608 BUG();
2609 anon_vma_unlock(anon_vma);
2610 }
2611}
2612
2613static void vm_unlock_mapping(struct address_space *mapping)
2614{
2615 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2616 /*
2617 * AS_MM_ALL_LOCKS can't change to 0 from under us
2618 * because we hold the mm_all_locks_mutex.
2619 */
2620 mutex_unlock(&mapping->i_mmap_mutex);
2621 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
2622 &mapping->flags))
2623 BUG();
2624 }
2625}
2626
2627/*
2628 * The mmap_sem cannot be released by the caller until
2629 * mm_drop_all_locks() returns.
2630 */
2631void mm_drop_all_locks(struct mm_struct *mm)
2632{
2633 struct vm_area_struct *vma;
2634 struct anon_vma_chain *avc;
2635
2636 BUG_ON(down_read_trylock(&mm->mmap_sem));
2637 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
2638
2639 for (vma = mm->mmap; vma; vma = vma->vm_next) {
2640 if (vma->anon_vma)
2641 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2642 vm_unlock_anon_vma(avc->anon_vma);
2643 if (vma->vm_file && vma->vm_file->f_mapping)
2644 vm_unlock_mapping(vma->vm_file->f_mapping);
2645 }
2646
2647 mutex_unlock(&mm_all_locks_mutex);
2648}
2649
2650/*
2651 * initialise the VMA slab
2652 */
2653void __init mmap_init(void)
2654{
2655 int ret;
2656
2657 ret = percpu_counter_init(&vm_committed_as, 0);
2658 VM_BUG_ON(ret);
2659}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * mm/mmap.c
4 *
5 * Written by obz.
6 *
7 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
8 */
9
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12#include <linux/kernel.h>
13#include <linux/slab.h>
14#include <linux/backing-dev.h>
15#include <linux/mm.h>
16#include <linux/mm_inline.h>
17#include <linux/shm.h>
18#include <linux/mman.h>
19#include <linux/pagemap.h>
20#include <linux/swap.h>
21#include <linux/syscalls.h>
22#include <linux/capability.h>
23#include <linux/init.h>
24#include <linux/file.h>
25#include <linux/fs.h>
26#include <linux/personality.h>
27#include <linux/security.h>
28#include <linux/hugetlb.h>
29#include <linux/shmem_fs.h>
30#include <linux/profile.h>
31#include <linux/export.h>
32#include <linux/mount.h>
33#include <linux/mempolicy.h>
34#include <linux/rmap.h>
35#include <linux/mmu_notifier.h>
36#include <linux/mmdebug.h>
37#include <linux/perf_event.h>
38#include <linux/audit.h>
39#include <linux/khugepaged.h>
40#include <linux/uprobes.h>
41#include <linux/notifier.h>
42#include <linux/memory.h>
43#include <linux/printk.h>
44#include <linux/userfaultfd_k.h>
45#include <linux/moduleparam.h>
46#include <linux/pkeys.h>
47#include <linux/oom.h>
48#include <linux/sched/mm.h>
49#include <linux/ksm.h>
50
51#include <linux/uaccess.h>
52#include <asm/cacheflush.h>
53#include <asm/tlb.h>
54#include <asm/mmu_context.h>
55
56#define CREATE_TRACE_POINTS
57#include <trace/events/mmap.h>
58
59#include "internal.h"
60
61#ifndef arch_mmap_check
62#define arch_mmap_check(addr, len, flags) (0)
63#endif
64
65#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
66const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
67int mmap_rnd_bits_max __ro_after_init = CONFIG_ARCH_MMAP_RND_BITS_MAX;
68int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
69#endif
70#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
71const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
72const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
73int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
74#endif
75
76static bool ignore_rlimit_data;
77core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
78
79static void unmap_region(struct mm_struct *mm, struct ma_state *mas,
80 struct vm_area_struct *vma, struct vm_area_struct *prev,
81 struct vm_area_struct *next, unsigned long start,
82 unsigned long end, unsigned long tree_end, bool mm_wr_locked);
83
84static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
85{
86 return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
87}
88
89/* Update vma->vm_page_prot to reflect vma->vm_flags. */
90void vma_set_page_prot(struct vm_area_struct *vma)
91{
92 unsigned long vm_flags = vma->vm_flags;
93 pgprot_t vm_page_prot;
94
95 vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
96 if (vma_wants_writenotify(vma, vm_page_prot)) {
97 vm_flags &= ~VM_SHARED;
98 vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags);
99 }
100 /* remove_protection_ptes reads vma->vm_page_prot without mmap_lock */
101 WRITE_ONCE(vma->vm_page_prot, vm_page_prot);
102}
103
104/*
105 * Requires inode->i_mapping->i_mmap_rwsem
106 */
107static void __remove_shared_vm_struct(struct vm_area_struct *vma,
108 struct address_space *mapping)
109{
110 if (vma_is_shared_maywrite(vma))
111 mapping_unmap_writable(mapping);
112
113 flush_dcache_mmap_lock(mapping);
114 vma_interval_tree_remove(vma, &mapping->i_mmap);
115 flush_dcache_mmap_unlock(mapping);
116}
117
118/*
119 * Unlink a file-based vm structure from its interval tree, to hide
120 * vma from rmap and vmtruncate before freeing its page tables.
121 */
122void unlink_file_vma(struct vm_area_struct *vma)
123{
124 struct file *file = vma->vm_file;
125
126 if (file) {
127 struct address_space *mapping = file->f_mapping;
128 i_mmap_lock_write(mapping);
129 __remove_shared_vm_struct(vma, mapping);
130 i_mmap_unlock_write(mapping);
131 }
132}
133
134/*
135 * Close a vm structure and free it.
136 */
137static void remove_vma(struct vm_area_struct *vma, bool unreachable)
138{
139 might_sleep();
140 if (vma->vm_ops && vma->vm_ops->close)
141 vma->vm_ops->close(vma);
142 if (vma->vm_file)
143 fput(vma->vm_file);
144 mpol_put(vma_policy(vma));
145 if (unreachable)
146 __vm_area_free(vma);
147 else
148 vm_area_free(vma);
149}
150
151static inline struct vm_area_struct *vma_prev_limit(struct vma_iterator *vmi,
152 unsigned long min)
153{
154 return mas_prev(&vmi->mas, min);
155}
156
157/*
158 * check_brk_limits() - Use platform specific check of range & verify mlock
159 * limits.
160 * @addr: The address to check
161 * @len: The size of increase.
162 *
163 * Return: 0 on success.
164 */
165static int check_brk_limits(unsigned long addr, unsigned long len)
166{
167 unsigned long mapped_addr;
168
169 mapped_addr = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
170 if (IS_ERR_VALUE(mapped_addr))
171 return mapped_addr;
172
173 return mlock_future_ok(current->mm, current->mm->def_flags, len)
174 ? 0 : -EAGAIN;
175}
176static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *brkvma,
177 unsigned long addr, unsigned long request, unsigned long flags);
178SYSCALL_DEFINE1(brk, unsigned long, brk)
179{
180 unsigned long newbrk, oldbrk, origbrk;
181 struct mm_struct *mm = current->mm;
182 struct vm_area_struct *brkvma, *next = NULL;
183 unsigned long min_brk;
184 bool populate = false;
185 LIST_HEAD(uf);
186 struct vma_iterator vmi;
187
188 if (mmap_write_lock_killable(mm))
189 return -EINTR;
190
191 origbrk = mm->brk;
192
193#ifdef CONFIG_COMPAT_BRK
194 /*
195 * CONFIG_COMPAT_BRK can still be overridden by setting
196 * randomize_va_space to 2, which will still cause mm->start_brk
197 * to be arbitrarily shifted
198 */
199 if (current->brk_randomized)
200 min_brk = mm->start_brk;
201 else
202 min_brk = mm->end_data;
203#else
204 min_brk = mm->start_brk;
205#endif
206 if (brk < min_brk)
207 goto out;
208
209 /*
210 * Check against rlimit here. If this check is done later after the test
211 * of oldbrk with newbrk then it can escape the test and let the data
212 * segment grow beyond its set limit the in case where the limit is
213 * not page aligned -Ram Gupta
214 */
215 if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
216 mm->end_data, mm->start_data))
217 goto out;
218
219 newbrk = PAGE_ALIGN(brk);
220 oldbrk = PAGE_ALIGN(mm->brk);
221 if (oldbrk == newbrk) {
222 mm->brk = brk;
223 goto success;
224 }
225
226 /* Always allow shrinking brk. */
227 if (brk <= mm->brk) {
228 /* Search one past newbrk */
229 vma_iter_init(&vmi, mm, newbrk);
230 brkvma = vma_find(&vmi, oldbrk);
231 if (!brkvma || brkvma->vm_start >= oldbrk)
232 goto out; /* mapping intersects with an existing non-brk vma. */
233 /*
234 * mm->brk must be protected by write mmap_lock.
235 * do_vma_munmap() will drop the lock on success, so update it
236 * before calling do_vma_munmap().
237 */
238 mm->brk = brk;
239 if (do_vma_munmap(&vmi, brkvma, newbrk, oldbrk, &uf, true))
240 goto out;
241
242 goto success_unlocked;
243 }
244
245 if (check_brk_limits(oldbrk, newbrk - oldbrk))
246 goto out;
247
248 /*
249 * Only check if the next VMA is within the stack_guard_gap of the
250 * expansion area
251 */
252 vma_iter_init(&vmi, mm, oldbrk);
253 next = vma_find(&vmi, newbrk + PAGE_SIZE + stack_guard_gap);
254 if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
255 goto out;
256
257 brkvma = vma_prev_limit(&vmi, mm->start_brk);
258 /* Ok, looks good - let it rip. */
259 if (do_brk_flags(&vmi, brkvma, oldbrk, newbrk - oldbrk, 0) < 0)
260 goto out;
261
262 mm->brk = brk;
263 if (mm->def_flags & VM_LOCKED)
264 populate = true;
265
266success:
267 mmap_write_unlock(mm);
268success_unlocked:
269 userfaultfd_unmap_complete(mm, &uf);
270 if (populate)
271 mm_populate(oldbrk, newbrk - oldbrk);
272 return brk;
273
274out:
275 mm->brk = origbrk;
276 mmap_write_unlock(mm);
277 return origbrk;
278}
279
280#if defined(CONFIG_DEBUG_VM_MAPLE_TREE)
281static void validate_mm(struct mm_struct *mm)
282{
283 int bug = 0;
284 int i = 0;
285 struct vm_area_struct *vma;
286 VMA_ITERATOR(vmi, mm, 0);
287
288 mt_validate(&mm->mm_mt);
289 for_each_vma(vmi, vma) {
290#ifdef CONFIG_DEBUG_VM_RB
291 struct anon_vma *anon_vma = vma->anon_vma;
292 struct anon_vma_chain *avc;
293#endif
294 unsigned long vmi_start, vmi_end;
295 bool warn = 0;
296
297 vmi_start = vma_iter_addr(&vmi);
298 vmi_end = vma_iter_end(&vmi);
299 if (VM_WARN_ON_ONCE_MM(vma->vm_end != vmi_end, mm))
300 warn = 1;
301
302 if (VM_WARN_ON_ONCE_MM(vma->vm_start != vmi_start, mm))
303 warn = 1;
304
305 if (warn) {
306 pr_emerg("issue in %s\n", current->comm);
307 dump_stack();
308 dump_vma(vma);
309 pr_emerg("tree range: %px start %lx end %lx\n", vma,
310 vmi_start, vmi_end - 1);
311 vma_iter_dump_tree(&vmi);
312 }
313
314#ifdef CONFIG_DEBUG_VM_RB
315 if (anon_vma) {
316 anon_vma_lock_read(anon_vma);
317 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
318 anon_vma_interval_tree_verify(avc);
319 anon_vma_unlock_read(anon_vma);
320 }
321#endif
322 i++;
323 }
324 if (i != mm->map_count) {
325 pr_emerg("map_count %d vma iterator %d\n", mm->map_count, i);
326 bug = 1;
327 }
328 VM_BUG_ON_MM(bug, mm);
329}
330
331#else /* !CONFIG_DEBUG_VM_MAPLE_TREE */
332#define validate_mm(mm) do { } while (0)
333#endif /* CONFIG_DEBUG_VM_MAPLE_TREE */
334
335/*
336 * vma has some anon_vma assigned, and is already inserted on that
337 * anon_vma's interval trees.
338 *
339 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
340 * vma must be removed from the anon_vma's interval trees using
341 * anon_vma_interval_tree_pre_update_vma().
342 *
343 * After the update, the vma will be reinserted using
344 * anon_vma_interval_tree_post_update_vma().
345 *
346 * The entire update must be protected by exclusive mmap_lock and by
347 * the root anon_vma's mutex.
348 */
349static inline void
350anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
351{
352 struct anon_vma_chain *avc;
353
354 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
355 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
356}
357
358static inline void
359anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
360{
361 struct anon_vma_chain *avc;
362
363 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
364 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
365}
366
367static unsigned long count_vma_pages_range(struct mm_struct *mm,
368 unsigned long addr, unsigned long end)
369{
370 VMA_ITERATOR(vmi, mm, addr);
371 struct vm_area_struct *vma;
372 unsigned long nr_pages = 0;
373
374 for_each_vma_range(vmi, vma, end) {
375 unsigned long vm_start = max(addr, vma->vm_start);
376 unsigned long vm_end = min(end, vma->vm_end);
377
378 nr_pages += PHYS_PFN(vm_end - vm_start);
379 }
380
381 return nr_pages;
382}
383
384static void __vma_link_file(struct vm_area_struct *vma,
385 struct address_space *mapping)
386{
387 if (vma_is_shared_maywrite(vma))
388 mapping_allow_writable(mapping);
389
390 flush_dcache_mmap_lock(mapping);
391 vma_interval_tree_insert(vma, &mapping->i_mmap);
392 flush_dcache_mmap_unlock(mapping);
393}
394
395static void vma_link_file(struct vm_area_struct *vma)
396{
397 struct file *file = vma->vm_file;
398 struct address_space *mapping;
399
400 if (file) {
401 mapping = file->f_mapping;
402 i_mmap_lock_write(mapping);
403 __vma_link_file(vma, mapping);
404 i_mmap_unlock_write(mapping);
405 }
406}
407
408static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma)
409{
410 VMA_ITERATOR(vmi, mm, 0);
411
412 vma_iter_config(&vmi, vma->vm_start, vma->vm_end);
413 if (vma_iter_prealloc(&vmi, vma))
414 return -ENOMEM;
415
416 vma_start_write(vma);
417 vma_iter_store(&vmi, vma);
418 vma_link_file(vma);
419 mm->map_count++;
420 validate_mm(mm);
421 return 0;
422}
423
424/*
425 * init_multi_vma_prep() - Initializer for struct vma_prepare
426 * @vp: The vma_prepare struct
427 * @vma: The vma that will be altered once locked
428 * @next: The next vma if it is to be adjusted
429 * @remove: The first vma to be removed
430 * @remove2: The second vma to be removed
431 */
432static inline void init_multi_vma_prep(struct vma_prepare *vp,
433 struct vm_area_struct *vma, struct vm_area_struct *next,
434 struct vm_area_struct *remove, struct vm_area_struct *remove2)
435{
436 memset(vp, 0, sizeof(struct vma_prepare));
437 vp->vma = vma;
438 vp->anon_vma = vma->anon_vma;
439 vp->remove = remove;
440 vp->remove2 = remove2;
441 vp->adj_next = next;
442 if (!vp->anon_vma && next)
443 vp->anon_vma = next->anon_vma;
444
445 vp->file = vma->vm_file;
446 if (vp->file)
447 vp->mapping = vma->vm_file->f_mapping;
448
449}
450
451/*
452 * init_vma_prep() - Initializer wrapper for vma_prepare struct
453 * @vp: The vma_prepare struct
454 * @vma: The vma that will be altered once locked
455 */
456static inline void init_vma_prep(struct vma_prepare *vp,
457 struct vm_area_struct *vma)
458{
459 init_multi_vma_prep(vp, vma, NULL, NULL, NULL);
460}
461
462
463/*
464 * vma_prepare() - Helper function for handling locking VMAs prior to altering
465 * @vp: The initialized vma_prepare struct
466 */
467static inline void vma_prepare(struct vma_prepare *vp)
468{
469 if (vp->file) {
470 uprobe_munmap(vp->vma, vp->vma->vm_start, vp->vma->vm_end);
471
472 if (vp->adj_next)
473 uprobe_munmap(vp->adj_next, vp->adj_next->vm_start,
474 vp->adj_next->vm_end);
475
476 i_mmap_lock_write(vp->mapping);
477 if (vp->insert && vp->insert->vm_file) {
478 /*
479 * Put into interval tree now, so instantiated pages
480 * are visible to arm/parisc __flush_dcache_page
481 * throughout; but we cannot insert into address
482 * space until vma start or end is updated.
483 */
484 __vma_link_file(vp->insert,
485 vp->insert->vm_file->f_mapping);
486 }
487 }
488
489 if (vp->anon_vma) {
490 anon_vma_lock_write(vp->anon_vma);
491 anon_vma_interval_tree_pre_update_vma(vp->vma);
492 if (vp->adj_next)
493 anon_vma_interval_tree_pre_update_vma(vp->adj_next);
494 }
495
496 if (vp->file) {
497 flush_dcache_mmap_lock(vp->mapping);
498 vma_interval_tree_remove(vp->vma, &vp->mapping->i_mmap);
499 if (vp->adj_next)
500 vma_interval_tree_remove(vp->adj_next,
501 &vp->mapping->i_mmap);
502 }
503
504}
505
506/*
507 * vma_complete- Helper function for handling the unlocking after altering VMAs,
508 * or for inserting a VMA.
509 *
510 * @vp: The vma_prepare struct
511 * @vmi: The vma iterator
512 * @mm: The mm_struct
513 */
514static inline void vma_complete(struct vma_prepare *vp,
515 struct vma_iterator *vmi, struct mm_struct *mm)
516{
517 if (vp->file) {
518 if (vp->adj_next)
519 vma_interval_tree_insert(vp->adj_next,
520 &vp->mapping->i_mmap);
521 vma_interval_tree_insert(vp->vma, &vp->mapping->i_mmap);
522 flush_dcache_mmap_unlock(vp->mapping);
523 }
524
525 if (vp->remove && vp->file) {
526 __remove_shared_vm_struct(vp->remove, vp->mapping);
527 if (vp->remove2)
528 __remove_shared_vm_struct(vp->remove2, vp->mapping);
529 } else if (vp->insert) {
530 /*
531 * split_vma has split insert from vma, and needs
532 * us to insert it before dropping the locks
533 * (it may either follow vma or precede it).
534 */
535 vma_iter_store(vmi, vp->insert);
536 mm->map_count++;
537 }
538
539 if (vp->anon_vma) {
540 anon_vma_interval_tree_post_update_vma(vp->vma);
541 if (vp->adj_next)
542 anon_vma_interval_tree_post_update_vma(vp->adj_next);
543 anon_vma_unlock_write(vp->anon_vma);
544 }
545
546 if (vp->file) {
547 i_mmap_unlock_write(vp->mapping);
548 uprobe_mmap(vp->vma);
549
550 if (vp->adj_next)
551 uprobe_mmap(vp->adj_next);
552 }
553
554 if (vp->remove) {
555again:
556 vma_mark_detached(vp->remove, true);
557 if (vp->file) {
558 uprobe_munmap(vp->remove, vp->remove->vm_start,
559 vp->remove->vm_end);
560 fput(vp->file);
561 }
562 if (vp->remove->anon_vma)
563 anon_vma_merge(vp->vma, vp->remove);
564 mm->map_count--;
565 mpol_put(vma_policy(vp->remove));
566 if (!vp->remove2)
567 WARN_ON_ONCE(vp->vma->vm_end < vp->remove->vm_end);
568 vm_area_free(vp->remove);
569
570 /*
571 * In mprotect's case 6 (see comments on vma_merge),
572 * we are removing both mid and next vmas
573 */
574 if (vp->remove2) {
575 vp->remove = vp->remove2;
576 vp->remove2 = NULL;
577 goto again;
578 }
579 }
580 if (vp->insert && vp->file)
581 uprobe_mmap(vp->insert);
582 validate_mm(mm);
583}
584
585/*
586 * dup_anon_vma() - Helper function to duplicate anon_vma
587 * @dst: The destination VMA
588 * @src: The source VMA
589 * @dup: Pointer to the destination VMA when successful.
590 *
591 * Returns: 0 on success.
592 */
593static inline int dup_anon_vma(struct vm_area_struct *dst,
594 struct vm_area_struct *src, struct vm_area_struct **dup)
595{
596 /*
597 * Easily overlooked: when mprotect shifts the boundary, make sure the
598 * expanding vma has anon_vma set if the shrinking vma had, to cover any
599 * anon pages imported.
600 */
601 if (src->anon_vma && !dst->anon_vma) {
602 int ret;
603
604 vma_assert_write_locked(dst);
605 dst->anon_vma = src->anon_vma;
606 ret = anon_vma_clone(dst, src);
607 if (ret)
608 return ret;
609
610 *dup = dst;
611 }
612
613 return 0;
614}
615
616/*
617 * vma_expand - Expand an existing VMA
618 *
619 * @vmi: The vma iterator
620 * @vma: The vma to expand
621 * @start: The start of the vma
622 * @end: The exclusive end of the vma
623 * @pgoff: The page offset of vma
624 * @next: The current of next vma.
625 *
626 * Expand @vma to @start and @end. Can expand off the start and end. Will
627 * expand over @next if it's different from @vma and @end == @next->vm_end.
628 * Checking if the @vma can expand and merge with @next needs to be handled by
629 * the caller.
630 *
631 * Returns: 0 on success
632 */
633int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,
634 unsigned long start, unsigned long end, pgoff_t pgoff,
635 struct vm_area_struct *next)
636{
637 struct vm_area_struct *anon_dup = NULL;
638 bool remove_next = false;
639 struct vma_prepare vp;
640
641 vma_start_write(vma);
642 if (next && (vma != next) && (end == next->vm_end)) {
643 int ret;
644
645 remove_next = true;
646 vma_start_write(next);
647 ret = dup_anon_vma(vma, next, &anon_dup);
648 if (ret)
649 return ret;
650 }
651
652 init_multi_vma_prep(&vp, vma, NULL, remove_next ? next : NULL, NULL);
653 /* Not merging but overwriting any part of next is not handled. */
654 VM_WARN_ON(next && !vp.remove &&
655 next != vma && end > next->vm_start);
656 /* Only handles expanding */
657 VM_WARN_ON(vma->vm_start < start || vma->vm_end > end);
658
659 /* Note: vma iterator must be pointing to 'start' */
660 vma_iter_config(vmi, start, end);
661 if (vma_iter_prealloc(vmi, vma))
662 goto nomem;
663
664 vma_prepare(&vp);
665 vma_adjust_trans_huge(vma, start, end, 0);
666 vma_set_range(vma, start, end, pgoff);
667 vma_iter_store(vmi, vma);
668
669 vma_complete(&vp, vmi, vma->vm_mm);
670 return 0;
671
672nomem:
673 if (anon_dup)
674 unlink_anon_vmas(anon_dup);
675 return -ENOMEM;
676}
677
678/*
679 * vma_shrink() - Reduce an existing VMAs memory area
680 * @vmi: The vma iterator
681 * @vma: The VMA to modify
682 * @start: The new start
683 * @end: The new end
684 *
685 * Returns: 0 on success, -ENOMEM otherwise
686 */
687int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
688 unsigned long start, unsigned long end, pgoff_t pgoff)
689{
690 struct vma_prepare vp;
691
692 WARN_ON((vma->vm_start != start) && (vma->vm_end != end));
693
694 if (vma->vm_start < start)
695 vma_iter_config(vmi, vma->vm_start, start);
696 else
697 vma_iter_config(vmi, end, vma->vm_end);
698
699 if (vma_iter_prealloc(vmi, NULL))
700 return -ENOMEM;
701
702 vma_start_write(vma);
703
704 init_vma_prep(&vp, vma);
705 vma_prepare(&vp);
706 vma_adjust_trans_huge(vma, start, end, 0);
707
708 vma_iter_clear(vmi);
709 vma_set_range(vma, start, end, pgoff);
710 vma_complete(&vp, vmi, vma->vm_mm);
711 return 0;
712}
713
714/*
715 * If the vma has a ->close operation then the driver probably needs to release
716 * per-vma resources, so we don't attempt to merge those if the caller indicates
717 * the current vma may be removed as part of the merge.
718 */
719static inline bool is_mergeable_vma(struct vm_area_struct *vma,
720 struct file *file, unsigned long vm_flags,
721 struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
722 struct anon_vma_name *anon_name, bool may_remove_vma)
723{
724 /*
725 * VM_SOFTDIRTY should not prevent from VMA merging, if we
726 * match the flags but dirty bit -- the caller should mark
727 * merged VMA as dirty. If dirty bit won't be excluded from
728 * comparison, we increase pressure on the memory system forcing
729 * the kernel to generate new VMAs when old one could be
730 * extended instead.
731 */
732 if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
733 return false;
734 if (vma->vm_file != file)
735 return false;
736 if (may_remove_vma && vma->vm_ops && vma->vm_ops->close)
737 return false;
738 if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
739 return false;
740 if (!anon_vma_name_eq(anon_vma_name(vma), anon_name))
741 return false;
742 return true;
743}
744
745static inline bool is_mergeable_anon_vma(struct anon_vma *anon_vma1,
746 struct anon_vma *anon_vma2, struct vm_area_struct *vma)
747{
748 /*
749 * The list_is_singular() test is to avoid merging VMA cloned from
750 * parents. This can improve scalability caused by anon_vma lock.
751 */
752 if ((!anon_vma1 || !anon_vma2) && (!vma ||
753 list_is_singular(&vma->anon_vma_chain)))
754 return true;
755 return anon_vma1 == anon_vma2;
756}
757
758/*
759 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
760 * in front of (at a lower virtual address and file offset than) the vma.
761 *
762 * We cannot merge two vmas if they have differently assigned (non-NULL)
763 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
764 *
765 * We don't check here for the merged mmap wrapping around the end of pagecache
766 * indices (16TB on ia32) because do_mmap() does not permit mmap's which
767 * wrap, nor mmaps which cover the final page at index -1UL.
768 *
769 * We assume the vma may be removed as part of the merge.
770 */
771static bool
772can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
773 struct anon_vma *anon_vma, struct file *file,
774 pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
775 struct anon_vma_name *anon_name)
776{
777 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, true) &&
778 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
779 if (vma->vm_pgoff == vm_pgoff)
780 return true;
781 }
782 return false;
783}
784
785/*
786 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
787 * beyond (at a higher virtual address and file offset than) the vma.
788 *
789 * We cannot merge two vmas if they have differently assigned (non-NULL)
790 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
791 *
792 * We assume that vma is not removed as part of the merge.
793 */
794static bool
795can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
796 struct anon_vma *anon_vma, struct file *file,
797 pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
798 struct anon_vma_name *anon_name)
799{
800 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, false) &&
801 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
802 pgoff_t vm_pglen;
803 vm_pglen = vma_pages(vma);
804 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
805 return true;
806 }
807 return false;
808}
809
810/*
811 * Given a mapping request (addr,end,vm_flags,file,pgoff,anon_name),
812 * figure out whether that can be merged with its predecessor or its
813 * successor. Or both (it neatly fills a hole).
814 *
815 * In most cases - when called for mmap, brk or mremap - [addr,end) is
816 * certain not to be mapped by the time vma_merge is called; but when
817 * called for mprotect, it is certain to be already mapped (either at
818 * an offset within prev, or at the start of next), and the flags of
819 * this area are about to be changed to vm_flags - and the no-change
820 * case has already been eliminated.
821 *
822 * The following mprotect cases have to be considered, where **** is
823 * the area passed down from mprotect_fixup, never extending beyond one
824 * vma, PPPP is the previous vma, CCCC is a concurrent vma that starts
825 * at the same address as **** and is of the same or larger span, and
826 * NNNN the next vma after ****:
827 *
828 * **** **** ****
829 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPCCCCCC
830 * cannot merge might become might become
831 * PPNNNNNNNNNN PPPPPPPPPPCC
832 * mmap, brk or case 4 below case 5 below
833 * mremap move:
834 * **** ****
835 * PPPP NNNN PPPPCCCCNNNN
836 * might become might become
837 * PPPPPPPPPPPP 1 or PPPPPPPPPPPP 6 or
838 * PPPPPPPPNNNN 2 or PPPPPPPPNNNN 7 or
839 * PPPPNNNNNNNN 3 PPPPNNNNNNNN 8
840 *
841 * It is important for case 8 that the vma CCCC overlapping the
842 * region **** is never going to extended over NNNN. Instead NNNN must
843 * be extended in region **** and CCCC must be removed. This way in
844 * all cases where vma_merge succeeds, the moment vma_merge drops the
845 * rmap_locks, the properties of the merged vma will be already
846 * correct for the whole merged range. Some of those properties like
847 * vm_page_prot/vm_flags may be accessed by rmap_walks and they must
848 * be correct for the whole merged range immediately after the
849 * rmap_locks are released. Otherwise if NNNN would be removed and
850 * CCCC would be extended over the NNNN range, remove_migration_ptes
851 * or other rmap walkers (if working on addresses beyond the "end"
852 * parameter) may establish ptes with the wrong permissions of CCCC
853 * instead of the right permissions of NNNN.
854 *
855 * In the code below:
856 * PPPP is represented by *prev
857 * CCCC is represented by *curr or not represented at all (NULL)
858 * NNNN is represented by *next or not represented at all (NULL)
859 * **** is not represented - it will be merged and the vma containing the
860 * area is returned, or the function will return NULL
861 */
862static struct vm_area_struct
863*vma_merge(struct vma_iterator *vmi, struct vm_area_struct *prev,
864 struct vm_area_struct *src, unsigned long addr, unsigned long end,
865 unsigned long vm_flags, pgoff_t pgoff, struct mempolicy *policy,
866 struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
867 struct anon_vma_name *anon_name)
868{
869 struct mm_struct *mm = src->vm_mm;
870 struct anon_vma *anon_vma = src->anon_vma;
871 struct file *file = src->vm_file;
872 struct vm_area_struct *curr, *next, *res;
873 struct vm_area_struct *vma, *adjust, *remove, *remove2;
874 struct vm_area_struct *anon_dup = NULL;
875 struct vma_prepare vp;
876 pgoff_t vma_pgoff;
877 int err = 0;
878 bool merge_prev = false;
879 bool merge_next = false;
880 bool vma_expanded = false;
881 unsigned long vma_start = addr;
882 unsigned long vma_end = end;
883 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
884 long adj_start = 0;
885
886 /*
887 * We later require that vma->vm_flags == vm_flags,
888 * so this tests vma->vm_flags & VM_SPECIAL, too.
889 */
890 if (vm_flags & VM_SPECIAL)
891 return NULL;
892
893 /* Does the input range span an existing VMA? (cases 5 - 8) */
894 curr = find_vma_intersection(mm, prev ? prev->vm_end : 0, end);
895
896 if (!curr || /* cases 1 - 4 */
897 end == curr->vm_end) /* cases 6 - 8, adjacent VMA */
898 next = vma_lookup(mm, end);
899 else
900 next = NULL; /* case 5 */
901
902 if (prev) {
903 vma_start = prev->vm_start;
904 vma_pgoff = prev->vm_pgoff;
905
906 /* Can we merge the predecessor? */
907 if (addr == prev->vm_end && mpol_equal(vma_policy(prev), policy)
908 && can_vma_merge_after(prev, vm_flags, anon_vma, file,
909 pgoff, vm_userfaultfd_ctx, anon_name)) {
910 merge_prev = true;
911 vma_prev(vmi);
912 }
913 }
914
915 /* Can we merge the successor? */
916 if (next && mpol_equal(policy, vma_policy(next)) &&
917 can_vma_merge_before(next, vm_flags, anon_vma, file, pgoff+pglen,
918 vm_userfaultfd_ctx, anon_name)) {
919 merge_next = true;
920 }
921
922 /* Verify some invariant that must be enforced by the caller. */
923 VM_WARN_ON(prev && addr <= prev->vm_start);
924 VM_WARN_ON(curr && (addr != curr->vm_start || end > curr->vm_end));
925 VM_WARN_ON(addr >= end);
926
927 if (!merge_prev && !merge_next)
928 return NULL; /* Not mergeable. */
929
930 if (merge_prev)
931 vma_start_write(prev);
932
933 res = vma = prev;
934 remove = remove2 = adjust = NULL;
935
936 /* Can we merge both the predecessor and the successor? */
937 if (merge_prev && merge_next &&
938 is_mergeable_anon_vma(prev->anon_vma, next->anon_vma, NULL)) {
939 vma_start_write(next);
940 remove = next; /* case 1 */
941 vma_end = next->vm_end;
942 err = dup_anon_vma(prev, next, &anon_dup);
943 if (curr) { /* case 6 */
944 vma_start_write(curr);
945 remove = curr;
946 remove2 = next;
947 /*
948 * Note that the dup_anon_vma below cannot overwrite err
949 * since the first caller would do nothing unless next
950 * has an anon_vma.
951 */
952 if (!next->anon_vma)
953 err = dup_anon_vma(prev, curr, &anon_dup);
954 }
955 } else if (merge_prev) { /* case 2 */
956 if (curr) {
957 vma_start_write(curr);
958 if (end == curr->vm_end) { /* case 7 */
959 /*
960 * can_vma_merge_after() assumed we would not be
961 * removing prev vma, so it skipped the check
962 * for vm_ops->close, but we are removing curr
963 */
964 if (curr->vm_ops && curr->vm_ops->close)
965 err = -EINVAL;
966 remove = curr;
967 } else { /* case 5 */
968 adjust = curr;
969 adj_start = (end - curr->vm_start);
970 }
971 if (!err)
972 err = dup_anon_vma(prev, curr, &anon_dup);
973 }
974 } else { /* merge_next */
975 vma_start_write(next);
976 res = next;
977 if (prev && addr < prev->vm_end) { /* case 4 */
978 vma_start_write(prev);
979 vma_end = addr;
980 adjust = next;
981 adj_start = -(prev->vm_end - addr);
982 err = dup_anon_vma(next, prev, &anon_dup);
983 } else {
984 /*
985 * Note that cases 3 and 8 are the ONLY ones where prev
986 * is permitted to be (but is not necessarily) NULL.
987 */
988 vma = next; /* case 3 */
989 vma_start = addr;
990 vma_end = next->vm_end;
991 vma_pgoff = next->vm_pgoff - pglen;
992 if (curr) { /* case 8 */
993 vma_pgoff = curr->vm_pgoff;
994 vma_start_write(curr);
995 remove = curr;
996 err = dup_anon_vma(next, curr, &anon_dup);
997 }
998 }
999 }
1000
1001 /* Error in anon_vma clone. */
1002 if (err)
1003 goto anon_vma_fail;
1004
1005 if (vma_start < vma->vm_start || vma_end > vma->vm_end)
1006 vma_expanded = true;
1007
1008 if (vma_expanded) {
1009 vma_iter_config(vmi, vma_start, vma_end);
1010 } else {
1011 vma_iter_config(vmi, adjust->vm_start + adj_start,
1012 adjust->vm_end);
1013 }
1014
1015 if (vma_iter_prealloc(vmi, vma))
1016 goto prealloc_fail;
1017
1018 init_multi_vma_prep(&vp, vma, adjust, remove, remove2);
1019 VM_WARN_ON(vp.anon_vma && adjust && adjust->anon_vma &&
1020 vp.anon_vma != adjust->anon_vma);
1021
1022 vma_prepare(&vp);
1023 vma_adjust_trans_huge(vma, vma_start, vma_end, adj_start);
1024 vma_set_range(vma, vma_start, vma_end, vma_pgoff);
1025
1026 if (vma_expanded)
1027 vma_iter_store(vmi, vma);
1028
1029 if (adj_start) {
1030 adjust->vm_start += adj_start;
1031 adjust->vm_pgoff += adj_start >> PAGE_SHIFT;
1032 if (adj_start < 0) {
1033 WARN_ON(vma_expanded);
1034 vma_iter_store(vmi, next);
1035 }
1036 }
1037
1038 vma_complete(&vp, vmi, mm);
1039 khugepaged_enter_vma(res, vm_flags);
1040 return res;
1041
1042prealloc_fail:
1043 if (anon_dup)
1044 unlink_anon_vmas(anon_dup);
1045
1046anon_vma_fail:
1047 vma_iter_set(vmi, addr);
1048 vma_iter_load(vmi);
1049 return NULL;
1050}
1051
1052/*
1053 * Rough compatibility check to quickly see if it's even worth looking
1054 * at sharing an anon_vma.
1055 *
1056 * They need to have the same vm_file, and the flags can only differ
1057 * in things that mprotect may change.
1058 *
1059 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1060 * we can merge the two vma's. For example, we refuse to merge a vma if
1061 * there is a vm_ops->close() function, because that indicates that the
1062 * driver is doing some kind of reference counting. But that doesn't
1063 * really matter for the anon_vma sharing case.
1064 */
1065static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1066{
1067 return a->vm_end == b->vm_start &&
1068 mpol_equal(vma_policy(a), vma_policy(b)) &&
1069 a->vm_file == b->vm_file &&
1070 !((a->vm_flags ^ b->vm_flags) & ~(VM_ACCESS_FLAGS | VM_SOFTDIRTY)) &&
1071 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1072}
1073
1074/*
1075 * Do some basic sanity checking to see if we can re-use the anon_vma
1076 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1077 * the same as 'old', the other will be the new one that is trying
1078 * to share the anon_vma.
1079 *
1080 * NOTE! This runs with mmap_lock held for reading, so it is possible that
1081 * the anon_vma of 'old' is concurrently in the process of being set up
1082 * by another page fault trying to merge _that_. But that's ok: if it
1083 * is being set up, that automatically means that it will be a singleton
1084 * acceptable for merging, so we can do all of this optimistically. But
1085 * we do that READ_ONCE() to make sure that we never re-load the pointer.
1086 *
1087 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1088 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1089 * is to return an anon_vma that is "complex" due to having gone through
1090 * a fork).
1091 *
1092 * We also make sure that the two vma's are compatible (adjacent,
1093 * and with the same memory policies). That's all stable, even with just
1094 * a read lock on the mmap_lock.
1095 */
1096static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1097{
1098 if (anon_vma_compatible(a, b)) {
1099 struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
1100
1101 if (anon_vma && list_is_singular(&old->anon_vma_chain))
1102 return anon_vma;
1103 }
1104 return NULL;
1105}
1106
1107/*
1108 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1109 * neighbouring vmas for a suitable anon_vma, before it goes off
1110 * to allocate a new anon_vma. It checks because a repetitive
1111 * sequence of mprotects and faults may otherwise lead to distinct
1112 * anon_vmas being allocated, preventing vma merge in subsequent
1113 * mprotect.
1114 */
1115struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1116{
1117 MA_STATE(mas, &vma->vm_mm->mm_mt, vma->vm_end, vma->vm_end);
1118 struct anon_vma *anon_vma = NULL;
1119 struct vm_area_struct *prev, *next;
1120
1121 /* Try next first. */
1122 next = mas_walk(&mas);
1123 if (next) {
1124 anon_vma = reusable_anon_vma(next, vma, next);
1125 if (anon_vma)
1126 return anon_vma;
1127 }
1128
1129 prev = mas_prev(&mas, 0);
1130 VM_BUG_ON_VMA(prev != vma, vma);
1131 prev = mas_prev(&mas, 0);
1132 /* Try prev next. */
1133 if (prev)
1134 anon_vma = reusable_anon_vma(prev, prev, vma);
1135
1136 /*
1137 * We might reach here with anon_vma == NULL if we can't find
1138 * any reusable anon_vma.
1139 * There's no absolute need to look only at touching neighbours:
1140 * we could search further afield for "compatible" anon_vmas.
1141 * But it would probably just be a waste of time searching,
1142 * or lead to too many vmas hanging off the same anon_vma.
1143 * We're trying to allow mprotect remerging later on,
1144 * not trying to minimize memory used for anon_vmas.
1145 */
1146 return anon_vma;
1147}
1148
1149/*
1150 * If a hint addr is less than mmap_min_addr change hint to be as
1151 * low as possible but still greater than mmap_min_addr
1152 */
1153static inline unsigned long round_hint_to_min(unsigned long hint)
1154{
1155 hint &= PAGE_MASK;
1156 if (((void *)hint != NULL) &&
1157 (hint < mmap_min_addr))
1158 return PAGE_ALIGN(mmap_min_addr);
1159 return hint;
1160}
1161
1162bool mlock_future_ok(struct mm_struct *mm, unsigned long flags,
1163 unsigned long bytes)
1164{
1165 unsigned long locked_pages, limit_pages;
1166
1167 if (!(flags & VM_LOCKED) || capable(CAP_IPC_LOCK))
1168 return true;
1169
1170 locked_pages = bytes >> PAGE_SHIFT;
1171 locked_pages += mm->locked_vm;
1172
1173 limit_pages = rlimit(RLIMIT_MEMLOCK);
1174 limit_pages >>= PAGE_SHIFT;
1175
1176 return locked_pages <= limit_pages;
1177}
1178
1179static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
1180{
1181 if (S_ISREG(inode->i_mode))
1182 return MAX_LFS_FILESIZE;
1183
1184 if (S_ISBLK(inode->i_mode))
1185 return MAX_LFS_FILESIZE;
1186
1187 if (S_ISSOCK(inode->i_mode))
1188 return MAX_LFS_FILESIZE;
1189
1190 /* Special "we do even unsigned file positions" case */
1191 if (file->f_mode & FMODE_UNSIGNED_OFFSET)
1192 return 0;
1193
1194 /* Yes, random drivers might want more. But I'm tired of buggy drivers */
1195 return ULONG_MAX;
1196}
1197
1198static inline bool file_mmap_ok(struct file *file, struct inode *inode,
1199 unsigned long pgoff, unsigned long len)
1200{
1201 u64 maxsize = file_mmap_size_max(file, inode);
1202
1203 if (maxsize && len > maxsize)
1204 return false;
1205 maxsize -= len;
1206 if (pgoff > maxsize >> PAGE_SHIFT)
1207 return false;
1208 return true;
1209}
1210
1211/*
1212 * The caller must write-lock current->mm->mmap_lock.
1213 */
1214unsigned long do_mmap(struct file *file, unsigned long addr,
1215 unsigned long len, unsigned long prot,
1216 unsigned long flags, vm_flags_t vm_flags,
1217 unsigned long pgoff, unsigned long *populate,
1218 struct list_head *uf)
1219{
1220 struct mm_struct *mm = current->mm;
1221 int pkey = 0;
1222
1223 *populate = 0;
1224
1225 if (!len)
1226 return -EINVAL;
1227
1228 /*
1229 * Does the application expect PROT_READ to imply PROT_EXEC?
1230 *
1231 * (the exception is when the underlying filesystem is noexec
1232 * mounted, in which case we don't add PROT_EXEC.)
1233 */
1234 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1235 if (!(file && path_noexec(&file->f_path)))
1236 prot |= PROT_EXEC;
1237
1238 /* force arch specific MAP_FIXED handling in get_unmapped_area */
1239 if (flags & MAP_FIXED_NOREPLACE)
1240 flags |= MAP_FIXED;
1241
1242 if (!(flags & MAP_FIXED))
1243 addr = round_hint_to_min(addr);
1244
1245 /* Careful about overflows.. */
1246 len = PAGE_ALIGN(len);
1247 if (!len)
1248 return -ENOMEM;
1249
1250 /* offset overflow? */
1251 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1252 return -EOVERFLOW;
1253
1254 /* Too many mappings? */
1255 if (mm->map_count > sysctl_max_map_count)
1256 return -ENOMEM;
1257
1258 /* Obtain the address to map to. we verify (or select) it and ensure
1259 * that it represents a valid section of the address space.
1260 */
1261 addr = get_unmapped_area(file, addr, len, pgoff, flags);
1262 if (IS_ERR_VALUE(addr))
1263 return addr;
1264
1265 if (flags & MAP_FIXED_NOREPLACE) {
1266 if (find_vma_intersection(mm, addr, addr + len))
1267 return -EEXIST;
1268 }
1269
1270 if (prot == PROT_EXEC) {
1271 pkey = execute_only_pkey(mm);
1272 if (pkey < 0)
1273 pkey = 0;
1274 }
1275
1276 /* Do simple checking here so the lower-level routines won't have
1277 * to. we assume access permissions have been handled by the open
1278 * of the memory object, so we don't do any here.
1279 */
1280 vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
1281 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1282
1283 if (flags & MAP_LOCKED)
1284 if (!can_do_mlock())
1285 return -EPERM;
1286
1287 if (!mlock_future_ok(mm, vm_flags, len))
1288 return -EAGAIN;
1289
1290 if (file) {
1291 struct inode *inode = file_inode(file);
1292 unsigned long flags_mask;
1293
1294 if (!file_mmap_ok(file, inode, pgoff, len))
1295 return -EOVERFLOW;
1296
1297 flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags;
1298
1299 switch (flags & MAP_TYPE) {
1300 case MAP_SHARED:
1301 /*
1302 * Force use of MAP_SHARED_VALIDATE with non-legacy
1303 * flags. E.g. MAP_SYNC is dangerous to use with
1304 * MAP_SHARED as you don't know which consistency model
1305 * you will get. We silently ignore unsupported flags
1306 * with MAP_SHARED to preserve backward compatibility.
1307 */
1308 flags &= LEGACY_MAP_MASK;
1309 fallthrough;
1310 case MAP_SHARED_VALIDATE:
1311 if (flags & ~flags_mask)
1312 return -EOPNOTSUPP;
1313 if (prot & PROT_WRITE) {
1314 if (!(file->f_mode & FMODE_WRITE))
1315 return -EACCES;
1316 if (IS_SWAPFILE(file->f_mapping->host))
1317 return -ETXTBSY;
1318 }
1319
1320 /*
1321 * Make sure we don't allow writing to an append-only
1322 * file..
1323 */
1324 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1325 return -EACCES;
1326
1327 vm_flags |= VM_SHARED | VM_MAYSHARE;
1328 if (!(file->f_mode & FMODE_WRITE))
1329 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1330 fallthrough;
1331 case MAP_PRIVATE:
1332 if (!(file->f_mode & FMODE_READ))
1333 return -EACCES;
1334 if (path_noexec(&file->f_path)) {
1335 if (vm_flags & VM_EXEC)
1336 return -EPERM;
1337 vm_flags &= ~VM_MAYEXEC;
1338 }
1339
1340 if (!file->f_op->mmap)
1341 return -ENODEV;
1342 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1343 return -EINVAL;
1344 break;
1345
1346 default:
1347 return -EINVAL;
1348 }
1349 } else {
1350 switch (flags & MAP_TYPE) {
1351 case MAP_SHARED:
1352 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1353 return -EINVAL;
1354 /*
1355 * Ignore pgoff.
1356 */
1357 pgoff = 0;
1358 vm_flags |= VM_SHARED | VM_MAYSHARE;
1359 break;
1360 case MAP_PRIVATE:
1361 /*
1362 * Set pgoff according to addr for anon_vma.
1363 */
1364 pgoff = addr >> PAGE_SHIFT;
1365 break;
1366 default:
1367 return -EINVAL;
1368 }
1369 }
1370
1371 /*
1372 * Set 'VM_NORESERVE' if we should not account for the
1373 * memory use of this mapping.
1374 */
1375 if (flags & MAP_NORESERVE) {
1376 /* We honor MAP_NORESERVE if allowed to overcommit */
1377 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1378 vm_flags |= VM_NORESERVE;
1379
1380 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1381 if (file && is_file_hugepages(file))
1382 vm_flags |= VM_NORESERVE;
1383 }
1384
1385 addr = mmap_region(file, addr, len, vm_flags, pgoff, uf);
1386 if (!IS_ERR_VALUE(addr) &&
1387 ((vm_flags & VM_LOCKED) ||
1388 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1389 *populate = len;
1390 return addr;
1391}
1392
1393unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
1394 unsigned long prot, unsigned long flags,
1395 unsigned long fd, unsigned long pgoff)
1396{
1397 struct file *file = NULL;
1398 unsigned long retval;
1399
1400 if (!(flags & MAP_ANONYMOUS)) {
1401 audit_mmap_fd(fd, flags);
1402 file = fget(fd);
1403 if (!file)
1404 return -EBADF;
1405 if (is_file_hugepages(file)) {
1406 len = ALIGN(len, huge_page_size(hstate_file(file)));
1407 } else if (unlikely(flags & MAP_HUGETLB)) {
1408 retval = -EINVAL;
1409 goto out_fput;
1410 }
1411 } else if (flags & MAP_HUGETLB) {
1412 struct hstate *hs;
1413
1414 hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1415 if (!hs)
1416 return -EINVAL;
1417
1418 len = ALIGN(len, huge_page_size(hs));
1419 /*
1420 * VM_NORESERVE is used because the reservations will be
1421 * taken when vm_ops->mmap() is called
1422 */
1423 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1424 VM_NORESERVE,
1425 HUGETLB_ANONHUGE_INODE,
1426 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1427 if (IS_ERR(file))
1428 return PTR_ERR(file);
1429 }
1430
1431 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1432out_fput:
1433 if (file)
1434 fput(file);
1435 return retval;
1436}
1437
1438SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1439 unsigned long, prot, unsigned long, flags,
1440 unsigned long, fd, unsigned long, pgoff)
1441{
1442 return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff);
1443}
1444
1445#ifdef __ARCH_WANT_SYS_OLD_MMAP
1446struct mmap_arg_struct {
1447 unsigned long addr;
1448 unsigned long len;
1449 unsigned long prot;
1450 unsigned long flags;
1451 unsigned long fd;
1452 unsigned long offset;
1453};
1454
1455SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1456{
1457 struct mmap_arg_struct a;
1458
1459 if (copy_from_user(&a, arg, sizeof(a)))
1460 return -EFAULT;
1461 if (offset_in_page(a.offset))
1462 return -EINVAL;
1463
1464 return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1465 a.offset >> PAGE_SHIFT);
1466}
1467#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1468
1469static bool vm_ops_needs_writenotify(const struct vm_operations_struct *vm_ops)
1470{
1471 return vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite);
1472}
1473
1474static bool vma_is_shared_writable(struct vm_area_struct *vma)
1475{
1476 return (vma->vm_flags & (VM_WRITE | VM_SHARED)) ==
1477 (VM_WRITE | VM_SHARED);
1478}
1479
1480static bool vma_fs_can_writeback(struct vm_area_struct *vma)
1481{
1482 /* No managed pages to writeback. */
1483 if (vma->vm_flags & VM_PFNMAP)
1484 return false;
1485
1486 return vma->vm_file && vma->vm_file->f_mapping &&
1487 mapping_can_writeback(vma->vm_file->f_mapping);
1488}
1489
1490/*
1491 * Does this VMA require the underlying folios to have their dirty state
1492 * tracked?
1493 */
1494bool vma_needs_dirty_tracking(struct vm_area_struct *vma)
1495{
1496 /* Only shared, writable VMAs require dirty tracking. */
1497 if (!vma_is_shared_writable(vma))
1498 return false;
1499
1500 /* Does the filesystem need to be notified? */
1501 if (vm_ops_needs_writenotify(vma->vm_ops))
1502 return true;
1503
1504 /*
1505 * Even if the filesystem doesn't indicate a need for writenotify, if it
1506 * can writeback, dirty tracking is still required.
1507 */
1508 return vma_fs_can_writeback(vma);
1509}
1510
1511/*
1512 * Some shared mappings will want the pages marked read-only
1513 * to track write events. If so, we'll downgrade vm_page_prot
1514 * to the private version (using protection_map[] without the
1515 * VM_SHARED bit).
1516 */
1517int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot)
1518{
1519 /* If it was private or non-writable, the write bit is already clear */
1520 if (!vma_is_shared_writable(vma))
1521 return 0;
1522
1523 /* The backer wishes to know when pages are first written to? */
1524 if (vm_ops_needs_writenotify(vma->vm_ops))
1525 return 1;
1526
1527 /* The open routine did something to the protections that pgprot_modify
1528 * won't preserve? */
1529 if (pgprot_val(vm_page_prot) !=
1530 pgprot_val(vm_pgprot_modify(vm_page_prot, vma->vm_flags)))
1531 return 0;
1532
1533 /*
1534 * Do we need to track softdirty? hugetlb does not support softdirty
1535 * tracking yet.
1536 */
1537 if (vma_soft_dirty_enabled(vma) && !is_vm_hugetlb_page(vma))
1538 return 1;
1539
1540 /* Do we need write faults for uffd-wp tracking? */
1541 if (userfaultfd_wp(vma))
1542 return 1;
1543
1544 /* Can the mapping track the dirty pages? */
1545 return vma_fs_can_writeback(vma);
1546}
1547
1548/*
1549 * We account for memory if it's a private writeable mapping,
1550 * not hugepages and VM_NORESERVE wasn't set.
1551 */
1552static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1553{
1554 /*
1555 * hugetlb has its own accounting separate from the core VM
1556 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1557 */
1558 if (file && is_file_hugepages(file))
1559 return 0;
1560
1561 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1562}
1563
1564/**
1565 * unmapped_area() - Find an area between the low_limit and the high_limit with
1566 * the correct alignment and offset, all from @info. Note: current->mm is used
1567 * for the search.
1568 *
1569 * @info: The unmapped area information including the range [low_limit -
1570 * high_limit), the alignment offset and mask.
1571 *
1572 * Return: A memory address or -ENOMEM.
1573 */
1574static unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1575{
1576 unsigned long length, gap;
1577 unsigned long low_limit, high_limit;
1578 struct vm_area_struct *tmp;
1579
1580 MA_STATE(mas, ¤t->mm->mm_mt, 0, 0);
1581
1582 /* Adjust search length to account for worst case alignment overhead */
1583 length = info->length + info->align_mask;
1584 if (length < info->length)
1585 return -ENOMEM;
1586
1587 low_limit = info->low_limit;
1588 if (low_limit < mmap_min_addr)
1589 low_limit = mmap_min_addr;
1590 high_limit = info->high_limit;
1591retry:
1592 if (mas_empty_area(&mas, low_limit, high_limit - 1, length))
1593 return -ENOMEM;
1594
1595 gap = mas.index;
1596 gap += (info->align_offset - gap) & info->align_mask;
1597 tmp = mas_next(&mas, ULONG_MAX);
1598 if (tmp && (tmp->vm_flags & VM_STARTGAP_FLAGS)) { /* Avoid prev check if possible */
1599 if (vm_start_gap(tmp) < gap + length - 1) {
1600 low_limit = tmp->vm_end;
1601 mas_reset(&mas);
1602 goto retry;
1603 }
1604 } else {
1605 tmp = mas_prev(&mas, 0);
1606 if (tmp && vm_end_gap(tmp) > gap) {
1607 low_limit = vm_end_gap(tmp);
1608 mas_reset(&mas);
1609 goto retry;
1610 }
1611 }
1612
1613 return gap;
1614}
1615
1616/**
1617 * unmapped_area_topdown() - Find an area between the low_limit and the
1618 * high_limit with the correct alignment and offset at the highest available
1619 * address, all from @info. Note: current->mm is used for the search.
1620 *
1621 * @info: The unmapped area information including the range [low_limit -
1622 * high_limit), the alignment offset and mask.
1623 *
1624 * Return: A memory address or -ENOMEM.
1625 */
1626static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
1627{
1628 unsigned long length, gap, gap_end;
1629 unsigned long low_limit, high_limit;
1630 struct vm_area_struct *tmp;
1631
1632 MA_STATE(mas, ¤t->mm->mm_mt, 0, 0);
1633 /* Adjust search length to account for worst case alignment overhead */
1634 length = info->length + info->align_mask;
1635 if (length < info->length)
1636 return -ENOMEM;
1637
1638 low_limit = info->low_limit;
1639 if (low_limit < mmap_min_addr)
1640 low_limit = mmap_min_addr;
1641 high_limit = info->high_limit;
1642retry:
1643 if (mas_empty_area_rev(&mas, low_limit, high_limit - 1, length))
1644 return -ENOMEM;
1645
1646 gap = mas.last + 1 - info->length;
1647 gap -= (gap - info->align_offset) & info->align_mask;
1648 gap_end = mas.last;
1649 tmp = mas_next(&mas, ULONG_MAX);
1650 if (tmp && (tmp->vm_flags & VM_STARTGAP_FLAGS)) { /* Avoid prev check if possible */
1651 if (vm_start_gap(tmp) <= gap_end) {
1652 high_limit = vm_start_gap(tmp);
1653 mas_reset(&mas);
1654 goto retry;
1655 }
1656 } else {
1657 tmp = mas_prev(&mas, 0);
1658 if (tmp && vm_end_gap(tmp) > gap) {
1659 high_limit = tmp->vm_start;
1660 mas_reset(&mas);
1661 goto retry;
1662 }
1663 }
1664
1665 return gap;
1666}
1667
1668/*
1669 * Search for an unmapped address range.
1670 *
1671 * We are looking for a range that:
1672 * - does not intersect with any VMA;
1673 * - is contained within the [low_limit, high_limit) interval;
1674 * - is at least the desired size.
1675 * - satisfies (begin_addr & align_mask) == (align_offset & align_mask)
1676 */
1677unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info)
1678{
1679 unsigned long addr;
1680
1681 if (info->flags & VM_UNMAPPED_AREA_TOPDOWN)
1682 addr = unmapped_area_topdown(info);
1683 else
1684 addr = unmapped_area(info);
1685
1686 trace_vm_unmapped_area(addr, info);
1687 return addr;
1688}
1689
1690/* Get an address range which is currently unmapped.
1691 * For shmat() with addr=0.
1692 *
1693 * Ugly calling convention alert:
1694 * Return value with the low bits set means error value,
1695 * ie
1696 * if (ret & ~PAGE_MASK)
1697 * error = ret;
1698 *
1699 * This function "knows" that -ENOMEM has the bits set.
1700 */
1701unsigned long
1702generic_get_unmapped_area(struct file *filp, unsigned long addr,
1703 unsigned long len, unsigned long pgoff,
1704 unsigned long flags)
1705{
1706 struct mm_struct *mm = current->mm;
1707 struct vm_area_struct *vma, *prev;
1708 struct vm_unmapped_area_info info;
1709 const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags);
1710
1711 if (len > mmap_end - mmap_min_addr)
1712 return -ENOMEM;
1713
1714 if (flags & MAP_FIXED)
1715 return addr;
1716
1717 if (addr) {
1718 addr = PAGE_ALIGN(addr);
1719 vma = find_vma_prev(mm, addr, &prev);
1720 if (mmap_end - len >= addr && addr >= mmap_min_addr &&
1721 (!vma || addr + len <= vm_start_gap(vma)) &&
1722 (!prev || addr >= vm_end_gap(prev)))
1723 return addr;
1724 }
1725
1726 info.flags = 0;
1727 info.length = len;
1728 info.low_limit = mm->mmap_base;
1729 info.high_limit = mmap_end;
1730 info.align_mask = 0;
1731 info.align_offset = 0;
1732 return vm_unmapped_area(&info);
1733}
1734
1735#ifndef HAVE_ARCH_UNMAPPED_AREA
1736unsigned long
1737arch_get_unmapped_area(struct file *filp, unsigned long addr,
1738 unsigned long len, unsigned long pgoff,
1739 unsigned long flags)
1740{
1741 return generic_get_unmapped_area(filp, addr, len, pgoff, flags);
1742}
1743#endif
1744
1745/*
1746 * This mmap-allocator allocates new areas top-down from below the
1747 * stack's low limit (the base):
1748 */
1749unsigned long
1750generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
1751 unsigned long len, unsigned long pgoff,
1752 unsigned long flags)
1753{
1754 struct vm_area_struct *vma, *prev;
1755 struct mm_struct *mm = current->mm;
1756 struct vm_unmapped_area_info info;
1757 const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags);
1758
1759 /* requested length too big for entire address space */
1760 if (len > mmap_end - mmap_min_addr)
1761 return -ENOMEM;
1762
1763 if (flags & MAP_FIXED)
1764 return addr;
1765
1766 /* requesting a specific address */
1767 if (addr) {
1768 addr = PAGE_ALIGN(addr);
1769 vma = find_vma_prev(mm, addr, &prev);
1770 if (mmap_end - len >= addr && addr >= mmap_min_addr &&
1771 (!vma || addr + len <= vm_start_gap(vma)) &&
1772 (!prev || addr >= vm_end_gap(prev)))
1773 return addr;
1774 }
1775
1776 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
1777 info.length = len;
1778 info.low_limit = PAGE_SIZE;
1779 info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
1780 info.align_mask = 0;
1781 info.align_offset = 0;
1782 addr = vm_unmapped_area(&info);
1783
1784 /*
1785 * A failed mmap() very likely causes application failure,
1786 * so fall back to the bottom-up function here. This scenario
1787 * can happen with large stack limits and large mmap()
1788 * allocations.
1789 */
1790 if (offset_in_page(addr)) {
1791 VM_BUG_ON(addr != -ENOMEM);
1792 info.flags = 0;
1793 info.low_limit = TASK_UNMAPPED_BASE;
1794 info.high_limit = mmap_end;
1795 addr = vm_unmapped_area(&info);
1796 }
1797
1798 return addr;
1799}
1800
1801#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1802unsigned long
1803arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
1804 unsigned long len, unsigned long pgoff,
1805 unsigned long flags)
1806{
1807 return generic_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
1808}
1809#endif
1810
1811unsigned long
1812get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1813 unsigned long pgoff, unsigned long flags)
1814{
1815 unsigned long (*get_area)(struct file *, unsigned long,
1816 unsigned long, unsigned long, unsigned long);
1817
1818 unsigned long error = arch_mmap_check(addr, len, flags);
1819 if (error)
1820 return error;
1821
1822 /* Careful about overflows.. */
1823 if (len > TASK_SIZE)
1824 return -ENOMEM;
1825
1826 get_area = current->mm->get_unmapped_area;
1827 if (file) {
1828 if (file->f_op->get_unmapped_area)
1829 get_area = file->f_op->get_unmapped_area;
1830 } else if (flags & MAP_SHARED) {
1831 /*
1832 * mmap_region() will call shmem_zero_setup() to create a file,
1833 * so use shmem's get_unmapped_area in case it can be huge.
1834 */
1835 get_area = shmem_get_unmapped_area;
1836 } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
1837 /* Ensures that larger anonymous mappings are THP aligned. */
1838 get_area = thp_get_unmapped_area;
1839 }
1840
1841 /* Always treat pgoff as zero for anonymous memory. */
1842 if (!file)
1843 pgoff = 0;
1844
1845 addr = get_area(file, addr, len, pgoff, flags);
1846 if (IS_ERR_VALUE(addr))
1847 return addr;
1848
1849 if (addr > TASK_SIZE - len)
1850 return -ENOMEM;
1851 if (offset_in_page(addr))
1852 return -EINVAL;
1853
1854 error = security_mmap_addr(addr);
1855 return error ? error : addr;
1856}
1857
1858EXPORT_SYMBOL(get_unmapped_area);
1859
1860/**
1861 * find_vma_intersection() - Look up the first VMA which intersects the interval
1862 * @mm: The process address space.
1863 * @start_addr: The inclusive start user address.
1864 * @end_addr: The exclusive end user address.
1865 *
1866 * Returns: The first VMA within the provided range, %NULL otherwise. Assumes
1867 * start_addr < end_addr.
1868 */
1869struct vm_area_struct *find_vma_intersection(struct mm_struct *mm,
1870 unsigned long start_addr,
1871 unsigned long end_addr)
1872{
1873 unsigned long index = start_addr;
1874
1875 mmap_assert_locked(mm);
1876 return mt_find(&mm->mm_mt, &index, end_addr - 1);
1877}
1878EXPORT_SYMBOL(find_vma_intersection);
1879
1880/**
1881 * find_vma() - Find the VMA for a given address, or the next VMA.
1882 * @mm: The mm_struct to check
1883 * @addr: The address
1884 *
1885 * Returns: The VMA associated with addr, or the next VMA.
1886 * May return %NULL in the case of no VMA at addr or above.
1887 */
1888struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1889{
1890 unsigned long index = addr;
1891
1892 mmap_assert_locked(mm);
1893 return mt_find(&mm->mm_mt, &index, ULONG_MAX);
1894}
1895EXPORT_SYMBOL(find_vma);
1896
1897/**
1898 * find_vma_prev() - Find the VMA for a given address, or the next vma and
1899 * set %pprev to the previous VMA, if any.
1900 * @mm: The mm_struct to check
1901 * @addr: The address
1902 * @pprev: The pointer to set to the previous VMA
1903 *
1904 * Note that RCU lock is missing here since the external mmap_lock() is used
1905 * instead.
1906 *
1907 * Returns: The VMA associated with @addr, or the next vma.
1908 * May return %NULL in the case of no vma at addr or above.
1909 */
1910struct vm_area_struct *
1911find_vma_prev(struct mm_struct *mm, unsigned long addr,
1912 struct vm_area_struct **pprev)
1913{
1914 struct vm_area_struct *vma;
1915 MA_STATE(mas, &mm->mm_mt, addr, addr);
1916
1917 vma = mas_walk(&mas);
1918 *pprev = mas_prev(&mas, 0);
1919 if (!vma)
1920 vma = mas_next(&mas, ULONG_MAX);
1921 return vma;
1922}
1923
1924/*
1925 * Verify that the stack growth is acceptable and
1926 * update accounting. This is shared with both the
1927 * grow-up and grow-down cases.
1928 */
1929static int acct_stack_growth(struct vm_area_struct *vma,
1930 unsigned long size, unsigned long grow)
1931{
1932 struct mm_struct *mm = vma->vm_mm;
1933 unsigned long new_start;
1934
1935 /* address space limit tests */
1936 if (!may_expand_vm(mm, vma->vm_flags, grow))
1937 return -ENOMEM;
1938
1939 /* Stack limit test */
1940 if (size > rlimit(RLIMIT_STACK))
1941 return -ENOMEM;
1942
1943 /* mlock limit tests */
1944 if (!mlock_future_ok(mm, vma->vm_flags, grow << PAGE_SHIFT))
1945 return -ENOMEM;
1946
1947 /* Check to ensure the stack will not grow into a hugetlb-only region */
1948 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1949 vma->vm_end - size;
1950 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1951 return -EFAULT;
1952
1953 /*
1954 * Overcommit.. This must be the final test, as it will
1955 * update security statistics.
1956 */
1957 if (security_vm_enough_memory_mm(mm, grow))
1958 return -ENOMEM;
1959
1960 return 0;
1961}
1962
1963#if defined(CONFIG_STACK_GROWSUP)
1964/*
1965 * PA-RISC uses this for its stack.
1966 * vma is the last one with address > vma->vm_end. Have to extend vma.
1967 */
1968static int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1969{
1970 struct mm_struct *mm = vma->vm_mm;
1971 struct vm_area_struct *next;
1972 unsigned long gap_addr;
1973 int error = 0;
1974 MA_STATE(mas, &mm->mm_mt, vma->vm_start, address);
1975
1976 if (!(vma->vm_flags & VM_GROWSUP))
1977 return -EFAULT;
1978
1979 /* Guard against exceeding limits of the address space. */
1980 address &= PAGE_MASK;
1981 if (address >= (TASK_SIZE & PAGE_MASK))
1982 return -ENOMEM;
1983 address += PAGE_SIZE;
1984
1985 /* Enforce stack_guard_gap */
1986 gap_addr = address + stack_guard_gap;
1987
1988 /* Guard against overflow */
1989 if (gap_addr < address || gap_addr > TASK_SIZE)
1990 gap_addr = TASK_SIZE;
1991
1992 next = find_vma_intersection(mm, vma->vm_end, gap_addr);
1993 if (next && vma_is_accessible(next)) {
1994 if (!(next->vm_flags & VM_GROWSUP))
1995 return -ENOMEM;
1996 /* Check that both stack segments have the same anon_vma? */
1997 }
1998
1999 if (next)
2000 mas_prev_range(&mas, address);
2001
2002 __mas_set_range(&mas, vma->vm_start, address - 1);
2003 if (mas_preallocate(&mas, vma, GFP_KERNEL))
2004 return -ENOMEM;
2005
2006 /* We must make sure the anon_vma is allocated. */
2007 if (unlikely(anon_vma_prepare(vma))) {
2008 mas_destroy(&mas);
2009 return -ENOMEM;
2010 }
2011
2012 /* Lock the VMA before expanding to prevent concurrent page faults */
2013 vma_start_write(vma);
2014 /*
2015 * vma->vm_start/vm_end cannot change under us because the caller
2016 * is required to hold the mmap_lock in read mode. We need the
2017 * anon_vma lock to serialize against concurrent expand_stacks.
2018 */
2019 anon_vma_lock_write(vma->anon_vma);
2020
2021 /* Somebody else might have raced and expanded it already */
2022 if (address > vma->vm_end) {
2023 unsigned long size, grow;
2024
2025 size = address - vma->vm_start;
2026 grow = (address - vma->vm_end) >> PAGE_SHIFT;
2027
2028 error = -ENOMEM;
2029 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2030 error = acct_stack_growth(vma, size, grow);
2031 if (!error) {
2032 /*
2033 * We only hold a shared mmap_lock lock here, so
2034 * we need to protect against concurrent vma
2035 * expansions. anon_vma_lock_write() doesn't
2036 * help here, as we don't guarantee that all
2037 * growable vmas in a mm share the same root
2038 * anon vma. So, we reuse mm->page_table_lock
2039 * to guard against concurrent vma expansions.
2040 */
2041 spin_lock(&mm->page_table_lock);
2042 if (vma->vm_flags & VM_LOCKED)
2043 mm->locked_vm += grow;
2044 vm_stat_account(mm, vma->vm_flags, grow);
2045 anon_vma_interval_tree_pre_update_vma(vma);
2046 vma->vm_end = address;
2047 /* Overwrite old entry in mtree. */
2048 mas_store_prealloc(&mas, vma);
2049 anon_vma_interval_tree_post_update_vma(vma);
2050 spin_unlock(&mm->page_table_lock);
2051
2052 perf_event_mmap(vma);
2053 }
2054 }
2055 }
2056 anon_vma_unlock_write(vma->anon_vma);
2057 mas_destroy(&mas);
2058 validate_mm(mm);
2059 return error;
2060}
2061#endif /* CONFIG_STACK_GROWSUP */
2062
2063/*
2064 * vma is the first one with address < vma->vm_start. Have to extend vma.
2065 * mmap_lock held for writing.
2066 */
2067int expand_downwards(struct vm_area_struct *vma, unsigned long address)
2068{
2069 struct mm_struct *mm = vma->vm_mm;
2070 MA_STATE(mas, &mm->mm_mt, vma->vm_start, vma->vm_start);
2071 struct vm_area_struct *prev;
2072 int error = 0;
2073
2074 if (!(vma->vm_flags & VM_GROWSDOWN))
2075 return -EFAULT;
2076
2077 address &= PAGE_MASK;
2078 if (address < mmap_min_addr || address < FIRST_USER_ADDRESS)
2079 return -EPERM;
2080
2081 /* Enforce stack_guard_gap */
2082 prev = mas_prev(&mas, 0);
2083 /* Check that both stack segments have the same anon_vma? */
2084 if (prev) {
2085 if (!(prev->vm_flags & VM_GROWSDOWN) &&
2086 vma_is_accessible(prev) &&
2087 (address - prev->vm_end < stack_guard_gap))
2088 return -ENOMEM;
2089 }
2090
2091 if (prev)
2092 mas_next_range(&mas, vma->vm_start);
2093
2094 __mas_set_range(&mas, address, vma->vm_end - 1);
2095 if (mas_preallocate(&mas, vma, GFP_KERNEL))
2096 return -ENOMEM;
2097
2098 /* We must make sure the anon_vma is allocated. */
2099 if (unlikely(anon_vma_prepare(vma))) {
2100 mas_destroy(&mas);
2101 return -ENOMEM;
2102 }
2103
2104 /* Lock the VMA before expanding to prevent concurrent page faults */
2105 vma_start_write(vma);
2106 /*
2107 * vma->vm_start/vm_end cannot change under us because the caller
2108 * is required to hold the mmap_lock in read mode. We need the
2109 * anon_vma lock to serialize against concurrent expand_stacks.
2110 */
2111 anon_vma_lock_write(vma->anon_vma);
2112
2113 /* Somebody else might have raced and expanded it already */
2114 if (address < vma->vm_start) {
2115 unsigned long size, grow;
2116
2117 size = vma->vm_end - address;
2118 grow = (vma->vm_start - address) >> PAGE_SHIFT;
2119
2120 error = -ENOMEM;
2121 if (grow <= vma->vm_pgoff) {
2122 error = acct_stack_growth(vma, size, grow);
2123 if (!error) {
2124 /*
2125 * We only hold a shared mmap_lock lock here, so
2126 * we need to protect against concurrent vma
2127 * expansions. anon_vma_lock_write() doesn't
2128 * help here, as we don't guarantee that all
2129 * growable vmas in a mm share the same root
2130 * anon vma. So, we reuse mm->page_table_lock
2131 * to guard against concurrent vma expansions.
2132 */
2133 spin_lock(&mm->page_table_lock);
2134 if (vma->vm_flags & VM_LOCKED)
2135 mm->locked_vm += grow;
2136 vm_stat_account(mm, vma->vm_flags, grow);
2137 anon_vma_interval_tree_pre_update_vma(vma);
2138 vma->vm_start = address;
2139 vma->vm_pgoff -= grow;
2140 /* Overwrite old entry in mtree. */
2141 mas_store_prealloc(&mas, vma);
2142 anon_vma_interval_tree_post_update_vma(vma);
2143 spin_unlock(&mm->page_table_lock);
2144
2145 perf_event_mmap(vma);
2146 }
2147 }
2148 }
2149 anon_vma_unlock_write(vma->anon_vma);
2150 mas_destroy(&mas);
2151 validate_mm(mm);
2152 return error;
2153}
2154
2155/* enforced gap between the expanding stack and other mappings. */
2156unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
2157
2158static int __init cmdline_parse_stack_guard_gap(char *p)
2159{
2160 unsigned long val;
2161 char *endptr;
2162
2163 val = simple_strtoul(p, &endptr, 10);
2164 if (!*endptr)
2165 stack_guard_gap = val << PAGE_SHIFT;
2166
2167 return 1;
2168}
2169__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
2170
2171#ifdef CONFIG_STACK_GROWSUP
2172int expand_stack_locked(struct vm_area_struct *vma, unsigned long address)
2173{
2174 return expand_upwards(vma, address);
2175}
2176
2177struct vm_area_struct *find_extend_vma_locked(struct mm_struct *mm, unsigned long addr)
2178{
2179 struct vm_area_struct *vma, *prev;
2180
2181 addr &= PAGE_MASK;
2182 vma = find_vma_prev(mm, addr, &prev);
2183 if (vma && (vma->vm_start <= addr))
2184 return vma;
2185 if (!prev)
2186 return NULL;
2187 if (expand_stack_locked(prev, addr))
2188 return NULL;
2189 if (prev->vm_flags & VM_LOCKED)
2190 populate_vma_page_range(prev, addr, prev->vm_end, NULL);
2191 return prev;
2192}
2193#else
2194int expand_stack_locked(struct vm_area_struct *vma, unsigned long address)
2195{
2196 return expand_downwards(vma, address);
2197}
2198
2199struct vm_area_struct *find_extend_vma_locked(struct mm_struct *mm, unsigned long addr)
2200{
2201 struct vm_area_struct *vma;
2202 unsigned long start;
2203
2204 addr &= PAGE_MASK;
2205 vma = find_vma(mm, addr);
2206 if (!vma)
2207 return NULL;
2208 if (vma->vm_start <= addr)
2209 return vma;
2210 start = vma->vm_start;
2211 if (expand_stack_locked(vma, addr))
2212 return NULL;
2213 if (vma->vm_flags & VM_LOCKED)
2214 populate_vma_page_range(vma, addr, start, NULL);
2215 return vma;
2216}
2217#endif
2218
2219#if defined(CONFIG_STACK_GROWSUP)
2220
2221#define vma_expand_up(vma,addr) expand_upwards(vma, addr)
2222#define vma_expand_down(vma, addr) (-EFAULT)
2223
2224#else
2225
2226#define vma_expand_up(vma,addr) (-EFAULT)
2227#define vma_expand_down(vma, addr) expand_downwards(vma, addr)
2228
2229#endif
2230
2231/*
2232 * expand_stack(): legacy interface for page faulting. Don't use unless
2233 * you have to.
2234 *
2235 * This is called with the mm locked for reading, drops the lock, takes
2236 * the lock for writing, tries to look up a vma again, expands it if
2237 * necessary, and downgrades the lock to reading again.
2238 *
2239 * If no vma is found or it can't be expanded, it returns NULL and has
2240 * dropped the lock.
2241 */
2242struct vm_area_struct *expand_stack(struct mm_struct *mm, unsigned long addr)
2243{
2244 struct vm_area_struct *vma, *prev;
2245
2246 mmap_read_unlock(mm);
2247 if (mmap_write_lock_killable(mm))
2248 return NULL;
2249
2250 vma = find_vma_prev(mm, addr, &prev);
2251 if (vma && vma->vm_start <= addr)
2252 goto success;
2253
2254 if (prev && !vma_expand_up(prev, addr)) {
2255 vma = prev;
2256 goto success;
2257 }
2258
2259 if (vma && !vma_expand_down(vma, addr))
2260 goto success;
2261
2262 mmap_write_unlock(mm);
2263 return NULL;
2264
2265success:
2266 mmap_write_downgrade(mm);
2267 return vma;
2268}
2269
2270/*
2271 * Ok - we have the memory areas we should free on a maple tree so release them,
2272 * and do the vma updates.
2273 *
2274 * Called with the mm semaphore held.
2275 */
2276static inline void remove_mt(struct mm_struct *mm, struct ma_state *mas)
2277{
2278 unsigned long nr_accounted = 0;
2279 struct vm_area_struct *vma;
2280
2281 /* Update high watermark before we lower total_vm */
2282 update_hiwater_vm(mm);
2283 mas_for_each(mas, vma, ULONG_MAX) {
2284 long nrpages = vma_pages(vma);
2285
2286 if (vma->vm_flags & VM_ACCOUNT)
2287 nr_accounted += nrpages;
2288 vm_stat_account(mm, vma->vm_flags, -nrpages);
2289 remove_vma(vma, false);
2290 }
2291 vm_unacct_memory(nr_accounted);
2292}
2293
2294/*
2295 * Get rid of page table information in the indicated region.
2296 *
2297 * Called with the mm semaphore held.
2298 */
2299static void unmap_region(struct mm_struct *mm, struct ma_state *mas,
2300 struct vm_area_struct *vma, struct vm_area_struct *prev,
2301 struct vm_area_struct *next, unsigned long start,
2302 unsigned long end, unsigned long tree_end, bool mm_wr_locked)
2303{
2304 struct mmu_gather tlb;
2305 unsigned long mt_start = mas->index;
2306
2307 lru_add_drain();
2308 tlb_gather_mmu(&tlb, mm);
2309 update_hiwater_rss(mm);
2310 unmap_vmas(&tlb, mas, vma, start, end, tree_end, mm_wr_locked);
2311 mas_set(mas, mt_start);
2312 free_pgtables(&tlb, mas, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2313 next ? next->vm_start : USER_PGTABLES_CEILING,
2314 mm_wr_locked);
2315 tlb_finish_mmu(&tlb);
2316}
2317
2318/*
2319 * __split_vma() bypasses sysctl_max_map_count checking. We use this where it
2320 * has already been checked or doesn't make sense to fail.
2321 * VMA Iterator will point to the end VMA.
2322 */
2323static int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
2324 unsigned long addr, int new_below)
2325{
2326 struct vma_prepare vp;
2327 struct vm_area_struct *new;
2328 int err;
2329
2330 WARN_ON(vma->vm_start >= addr);
2331 WARN_ON(vma->vm_end <= addr);
2332
2333 if (vma->vm_ops && vma->vm_ops->may_split) {
2334 err = vma->vm_ops->may_split(vma, addr);
2335 if (err)
2336 return err;
2337 }
2338
2339 new = vm_area_dup(vma);
2340 if (!new)
2341 return -ENOMEM;
2342
2343 if (new_below) {
2344 new->vm_end = addr;
2345 } else {
2346 new->vm_start = addr;
2347 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2348 }
2349
2350 err = -ENOMEM;
2351 vma_iter_config(vmi, new->vm_start, new->vm_end);
2352 if (vma_iter_prealloc(vmi, new))
2353 goto out_free_vma;
2354
2355 err = vma_dup_policy(vma, new);
2356 if (err)
2357 goto out_free_vmi;
2358
2359 err = anon_vma_clone(new, vma);
2360 if (err)
2361 goto out_free_mpol;
2362
2363 if (new->vm_file)
2364 get_file(new->vm_file);
2365
2366 if (new->vm_ops && new->vm_ops->open)
2367 new->vm_ops->open(new);
2368
2369 vma_start_write(vma);
2370 vma_start_write(new);
2371
2372 init_vma_prep(&vp, vma);
2373 vp.insert = new;
2374 vma_prepare(&vp);
2375 vma_adjust_trans_huge(vma, vma->vm_start, addr, 0);
2376
2377 if (new_below) {
2378 vma->vm_start = addr;
2379 vma->vm_pgoff += (addr - new->vm_start) >> PAGE_SHIFT;
2380 } else {
2381 vma->vm_end = addr;
2382 }
2383
2384 /* vma_complete stores the new vma */
2385 vma_complete(&vp, vmi, vma->vm_mm);
2386
2387 /* Success. */
2388 if (new_below)
2389 vma_next(vmi);
2390 return 0;
2391
2392out_free_mpol:
2393 mpol_put(vma_policy(new));
2394out_free_vmi:
2395 vma_iter_free(vmi);
2396out_free_vma:
2397 vm_area_free(new);
2398 return err;
2399}
2400
2401/*
2402 * Split a vma into two pieces at address 'addr', a new vma is allocated
2403 * either for the first part or the tail.
2404 */
2405static int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
2406 unsigned long addr, int new_below)
2407{
2408 if (vma->vm_mm->map_count >= sysctl_max_map_count)
2409 return -ENOMEM;
2410
2411 return __split_vma(vmi, vma, addr, new_below);
2412}
2413
2414/*
2415 * We are about to modify one or multiple of a VMA's flags, policy, userfaultfd
2416 * context and anonymous VMA name within the range [start, end).
2417 *
2418 * As a result, we might be able to merge the newly modified VMA range with an
2419 * adjacent VMA with identical properties.
2420 *
2421 * If no merge is possible and the range does not span the entirety of the VMA,
2422 * we then need to split the VMA to accommodate the change.
2423 *
2424 * The function returns either the merged VMA, the original VMA if a split was
2425 * required instead, or an error if the split failed.
2426 */
2427struct vm_area_struct *vma_modify(struct vma_iterator *vmi,
2428 struct vm_area_struct *prev,
2429 struct vm_area_struct *vma,
2430 unsigned long start, unsigned long end,
2431 unsigned long vm_flags,
2432 struct mempolicy *policy,
2433 struct vm_userfaultfd_ctx uffd_ctx,
2434 struct anon_vma_name *anon_name)
2435{
2436 pgoff_t pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
2437 struct vm_area_struct *merged;
2438
2439 merged = vma_merge(vmi, prev, vma, start, end, vm_flags,
2440 pgoff, policy, uffd_ctx, anon_name);
2441 if (merged)
2442 return merged;
2443
2444 if (vma->vm_start < start) {
2445 int err = split_vma(vmi, vma, start, 1);
2446
2447 if (err)
2448 return ERR_PTR(err);
2449 }
2450
2451 if (vma->vm_end > end) {
2452 int err = split_vma(vmi, vma, end, 0);
2453
2454 if (err)
2455 return ERR_PTR(err);
2456 }
2457
2458 return vma;
2459}
2460
2461/*
2462 * Attempt to merge a newly mapped VMA with those adjacent to it. The caller
2463 * must ensure that [start, end) does not overlap any existing VMA.
2464 */
2465static struct vm_area_struct
2466*vma_merge_new_vma(struct vma_iterator *vmi, struct vm_area_struct *prev,
2467 struct vm_area_struct *vma, unsigned long start,
2468 unsigned long end, pgoff_t pgoff)
2469{
2470 return vma_merge(vmi, prev, vma, start, end, vma->vm_flags, pgoff,
2471 vma_policy(vma), vma->vm_userfaultfd_ctx, anon_vma_name(vma));
2472}
2473
2474/*
2475 * Expand vma by delta bytes, potentially merging with an immediately adjacent
2476 * VMA with identical properties.
2477 */
2478struct vm_area_struct *vma_merge_extend(struct vma_iterator *vmi,
2479 struct vm_area_struct *vma,
2480 unsigned long delta)
2481{
2482 pgoff_t pgoff = vma->vm_pgoff + vma_pages(vma);
2483
2484 /* vma is specified as prev, so case 1 or 2 will apply. */
2485 return vma_merge(vmi, vma, vma, vma->vm_end, vma->vm_end + delta,
2486 vma->vm_flags, pgoff, vma_policy(vma),
2487 vma->vm_userfaultfd_ctx, anon_vma_name(vma));
2488}
2489
2490/*
2491 * do_vmi_align_munmap() - munmap the aligned region from @start to @end.
2492 * @vmi: The vma iterator
2493 * @vma: The starting vm_area_struct
2494 * @mm: The mm_struct
2495 * @start: The aligned start address to munmap.
2496 * @end: The aligned end address to munmap.
2497 * @uf: The userfaultfd list_head
2498 * @unlock: Set to true to drop the mmap_lock. unlocking only happens on
2499 * success.
2500 *
2501 * Return: 0 on success and drops the lock if so directed, error and leaves the
2502 * lock held otherwise.
2503 */
2504static int
2505do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
2506 struct mm_struct *mm, unsigned long start,
2507 unsigned long end, struct list_head *uf, bool unlock)
2508{
2509 struct vm_area_struct *prev, *next = NULL;
2510 struct maple_tree mt_detach;
2511 int count = 0;
2512 int error = -ENOMEM;
2513 unsigned long locked_vm = 0;
2514 MA_STATE(mas_detach, &mt_detach, 0, 0);
2515 mt_init_flags(&mt_detach, vmi->mas.tree->ma_flags & MT_FLAGS_LOCK_MASK);
2516 mt_on_stack(mt_detach);
2517
2518 /*
2519 * If we need to split any vma, do it now to save pain later.
2520 *
2521 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2522 * unmapped vm_area_struct will remain in use: so lower split_vma
2523 * places tmp vma above, and higher split_vma places tmp vma below.
2524 */
2525
2526 /* Does it split the first one? */
2527 if (start > vma->vm_start) {
2528
2529 /*
2530 * Make sure that map_count on return from munmap() will
2531 * not exceed its limit; but let map_count go just above
2532 * its limit temporarily, to help free resources as expected.
2533 */
2534 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2535 goto map_count_exceeded;
2536
2537 error = __split_vma(vmi, vma, start, 1);
2538 if (error)
2539 goto start_split_failed;
2540 }
2541
2542 /*
2543 * Detach a range of VMAs from the mm. Using next as a temp variable as
2544 * it is always overwritten.
2545 */
2546 next = vma;
2547 do {
2548 /* Does it split the end? */
2549 if (next->vm_end > end) {
2550 error = __split_vma(vmi, next, end, 0);
2551 if (error)
2552 goto end_split_failed;
2553 }
2554 vma_start_write(next);
2555 mas_set(&mas_detach, count);
2556 error = mas_store_gfp(&mas_detach, next, GFP_KERNEL);
2557 if (error)
2558 goto munmap_gather_failed;
2559 vma_mark_detached(next, true);
2560 if (next->vm_flags & VM_LOCKED)
2561 locked_vm += vma_pages(next);
2562
2563 count++;
2564 if (unlikely(uf)) {
2565 /*
2566 * If userfaultfd_unmap_prep returns an error the vmas
2567 * will remain split, but userland will get a
2568 * highly unexpected error anyway. This is no
2569 * different than the case where the first of the two
2570 * __split_vma fails, but we don't undo the first
2571 * split, despite we could. This is unlikely enough
2572 * failure that it's not worth optimizing it for.
2573 */
2574 error = userfaultfd_unmap_prep(next, start, end, uf);
2575
2576 if (error)
2577 goto userfaultfd_error;
2578 }
2579#ifdef CONFIG_DEBUG_VM_MAPLE_TREE
2580 BUG_ON(next->vm_start < start);
2581 BUG_ON(next->vm_start > end);
2582#endif
2583 } for_each_vma_range(*vmi, next, end);
2584
2585#if defined(CONFIG_DEBUG_VM_MAPLE_TREE)
2586 /* Make sure no VMAs are about to be lost. */
2587 {
2588 MA_STATE(test, &mt_detach, 0, 0);
2589 struct vm_area_struct *vma_mas, *vma_test;
2590 int test_count = 0;
2591
2592 vma_iter_set(vmi, start);
2593 rcu_read_lock();
2594 vma_test = mas_find(&test, count - 1);
2595 for_each_vma_range(*vmi, vma_mas, end) {
2596 BUG_ON(vma_mas != vma_test);
2597 test_count++;
2598 vma_test = mas_next(&test, count - 1);
2599 }
2600 rcu_read_unlock();
2601 BUG_ON(count != test_count);
2602 }
2603#endif
2604
2605 while (vma_iter_addr(vmi) > start)
2606 vma_iter_prev_range(vmi);
2607
2608 error = vma_iter_clear_gfp(vmi, start, end, GFP_KERNEL);
2609 if (error)
2610 goto clear_tree_failed;
2611
2612 /* Point of no return */
2613 mm->locked_vm -= locked_vm;
2614 mm->map_count -= count;
2615 if (unlock)
2616 mmap_write_downgrade(mm);
2617
2618 prev = vma_iter_prev_range(vmi);
2619 next = vma_next(vmi);
2620 if (next)
2621 vma_iter_prev_range(vmi);
2622
2623 /*
2624 * We can free page tables without write-locking mmap_lock because VMAs
2625 * were isolated before we downgraded mmap_lock.
2626 */
2627 mas_set(&mas_detach, 1);
2628 unmap_region(mm, &mas_detach, vma, prev, next, start, end, count,
2629 !unlock);
2630 /* Statistics and freeing VMAs */
2631 mas_set(&mas_detach, 0);
2632 remove_mt(mm, &mas_detach);
2633 validate_mm(mm);
2634 if (unlock)
2635 mmap_read_unlock(mm);
2636
2637 __mt_destroy(&mt_detach);
2638 return 0;
2639
2640clear_tree_failed:
2641userfaultfd_error:
2642munmap_gather_failed:
2643end_split_failed:
2644 mas_set(&mas_detach, 0);
2645 mas_for_each(&mas_detach, next, end)
2646 vma_mark_detached(next, false);
2647
2648 __mt_destroy(&mt_detach);
2649start_split_failed:
2650map_count_exceeded:
2651 validate_mm(mm);
2652 return error;
2653}
2654
2655/*
2656 * do_vmi_munmap() - munmap a given range.
2657 * @vmi: The vma iterator
2658 * @mm: The mm_struct
2659 * @start: The start address to munmap
2660 * @len: The length of the range to munmap
2661 * @uf: The userfaultfd list_head
2662 * @unlock: set to true if the user wants to drop the mmap_lock on success
2663 *
2664 * This function takes a @mas that is either pointing to the previous VMA or set
2665 * to MA_START and sets it up to remove the mapping(s). The @len will be
2666 * aligned and any arch_unmap work will be preformed.
2667 *
2668 * Return: 0 on success and drops the lock if so directed, error and leaves the
2669 * lock held otherwise.
2670 */
2671int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm,
2672 unsigned long start, size_t len, struct list_head *uf,
2673 bool unlock)
2674{
2675 unsigned long end;
2676 struct vm_area_struct *vma;
2677
2678 if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
2679 return -EINVAL;
2680
2681 end = start + PAGE_ALIGN(len);
2682 if (end == start)
2683 return -EINVAL;
2684
2685 /* arch_unmap() might do unmaps itself. */
2686 arch_unmap(mm, start, end);
2687
2688 /* Find the first overlapping VMA */
2689 vma = vma_find(vmi, end);
2690 if (!vma) {
2691 if (unlock)
2692 mmap_write_unlock(mm);
2693 return 0;
2694 }
2695
2696 return do_vmi_align_munmap(vmi, vma, mm, start, end, uf, unlock);
2697}
2698
2699/* do_munmap() - Wrapper function for non-maple tree aware do_munmap() calls.
2700 * @mm: The mm_struct
2701 * @start: The start address to munmap
2702 * @len: The length to be munmapped.
2703 * @uf: The userfaultfd list_head
2704 *
2705 * Return: 0 on success, error otherwise.
2706 */
2707int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
2708 struct list_head *uf)
2709{
2710 VMA_ITERATOR(vmi, mm, start);
2711
2712 return do_vmi_munmap(&vmi, mm, start, len, uf, false);
2713}
2714
2715unsigned long mmap_region(struct file *file, unsigned long addr,
2716 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
2717 struct list_head *uf)
2718{
2719 struct mm_struct *mm = current->mm;
2720 struct vm_area_struct *vma = NULL;
2721 struct vm_area_struct *next, *prev, *merge;
2722 pgoff_t pglen = len >> PAGE_SHIFT;
2723 unsigned long charged = 0;
2724 unsigned long end = addr + len;
2725 unsigned long merge_start = addr, merge_end = end;
2726 bool writable_file_mapping = false;
2727 pgoff_t vm_pgoff;
2728 int error;
2729 VMA_ITERATOR(vmi, mm, addr);
2730
2731 /* Check against address space limit. */
2732 if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
2733 unsigned long nr_pages;
2734
2735 /*
2736 * MAP_FIXED may remove pages of mappings that intersects with
2737 * requested mapping. Account for the pages it would unmap.
2738 */
2739 nr_pages = count_vma_pages_range(mm, addr, end);
2740
2741 if (!may_expand_vm(mm, vm_flags,
2742 (len >> PAGE_SHIFT) - nr_pages))
2743 return -ENOMEM;
2744 }
2745
2746 /* Unmap any existing mapping in the area */
2747 if (do_vmi_munmap(&vmi, mm, addr, len, uf, false))
2748 return -ENOMEM;
2749
2750 /*
2751 * Private writable mapping: check memory availability
2752 */
2753 if (accountable_mapping(file, vm_flags)) {
2754 charged = len >> PAGE_SHIFT;
2755 if (security_vm_enough_memory_mm(mm, charged))
2756 return -ENOMEM;
2757 vm_flags |= VM_ACCOUNT;
2758 }
2759
2760 next = vma_next(&vmi);
2761 prev = vma_prev(&vmi);
2762 if (vm_flags & VM_SPECIAL) {
2763 if (prev)
2764 vma_iter_next_range(&vmi);
2765 goto cannot_expand;
2766 }
2767
2768 /* Attempt to expand an old mapping */
2769 /* Check next */
2770 if (next && next->vm_start == end && !vma_policy(next) &&
2771 can_vma_merge_before(next, vm_flags, NULL, file, pgoff+pglen,
2772 NULL_VM_UFFD_CTX, NULL)) {
2773 merge_end = next->vm_end;
2774 vma = next;
2775 vm_pgoff = next->vm_pgoff - pglen;
2776 }
2777
2778 /* Check prev */
2779 if (prev && prev->vm_end == addr && !vma_policy(prev) &&
2780 (vma ? can_vma_merge_after(prev, vm_flags, vma->anon_vma, file,
2781 pgoff, vma->vm_userfaultfd_ctx, NULL) :
2782 can_vma_merge_after(prev, vm_flags, NULL, file, pgoff,
2783 NULL_VM_UFFD_CTX, NULL))) {
2784 merge_start = prev->vm_start;
2785 vma = prev;
2786 vm_pgoff = prev->vm_pgoff;
2787 } else if (prev) {
2788 vma_iter_next_range(&vmi);
2789 }
2790
2791 /* Actually expand, if possible */
2792 if (vma &&
2793 !vma_expand(&vmi, vma, merge_start, merge_end, vm_pgoff, next)) {
2794 khugepaged_enter_vma(vma, vm_flags);
2795 goto expanded;
2796 }
2797
2798 if (vma == prev)
2799 vma_iter_set(&vmi, addr);
2800cannot_expand:
2801
2802 /*
2803 * Determine the object being mapped and call the appropriate
2804 * specific mapper. the address has already been validated, but
2805 * not unmapped, but the maps are removed from the list.
2806 */
2807 vma = vm_area_alloc(mm);
2808 if (!vma) {
2809 error = -ENOMEM;
2810 goto unacct_error;
2811 }
2812
2813 vma_iter_config(&vmi, addr, end);
2814 vma_set_range(vma, addr, end, pgoff);
2815 vm_flags_init(vma, vm_flags);
2816 vma->vm_page_prot = vm_get_page_prot(vm_flags);
2817
2818 if (file) {
2819 vma->vm_file = get_file(file);
2820 error = call_mmap(file, vma);
2821 if (error)
2822 goto unmap_and_free_vma;
2823
2824 if (vma_is_shared_maywrite(vma)) {
2825 error = mapping_map_writable(file->f_mapping);
2826 if (error)
2827 goto close_and_free_vma;
2828
2829 writable_file_mapping = true;
2830 }
2831
2832 /*
2833 * Expansion is handled above, merging is handled below.
2834 * Drivers should not alter the address of the VMA.
2835 */
2836 error = -EINVAL;
2837 if (WARN_ON((addr != vma->vm_start)))
2838 goto close_and_free_vma;
2839
2840 vma_iter_config(&vmi, addr, end);
2841 /*
2842 * If vm_flags changed after call_mmap(), we should try merge
2843 * vma again as we may succeed this time.
2844 */
2845 if (unlikely(vm_flags != vma->vm_flags && prev)) {
2846 merge = vma_merge_new_vma(&vmi, prev, vma,
2847 vma->vm_start, vma->vm_end,
2848 vma->vm_pgoff);
2849 if (merge) {
2850 /*
2851 * ->mmap() can change vma->vm_file and fput
2852 * the original file. So fput the vma->vm_file
2853 * here or we would add an extra fput for file
2854 * and cause general protection fault
2855 * ultimately.
2856 */
2857 fput(vma->vm_file);
2858 vm_area_free(vma);
2859 vma = merge;
2860 /* Update vm_flags to pick up the change. */
2861 vm_flags = vma->vm_flags;
2862 goto unmap_writable;
2863 }
2864 }
2865
2866 vm_flags = vma->vm_flags;
2867 } else if (vm_flags & VM_SHARED) {
2868 error = shmem_zero_setup(vma);
2869 if (error)
2870 goto free_vma;
2871 } else {
2872 vma_set_anonymous(vma);
2873 }
2874
2875 if (map_deny_write_exec(vma, vma->vm_flags)) {
2876 error = -EACCES;
2877 goto close_and_free_vma;
2878 }
2879
2880 /* Allow architectures to sanity-check the vm_flags */
2881 error = -EINVAL;
2882 if (!arch_validate_flags(vma->vm_flags))
2883 goto close_and_free_vma;
2884
2885 error = -ENOMEM;
2886 if (vma_iter_prealloc(&vmi, vma))
2887 goto close_and_free_vma;
2888
2889 /* Lock the VMA since it is modified after insertion into VMA tree */
2890 vma_start_write(vma);
2891 vma_iter_store(&vmi, vma);
2892 mm->map_count++;
2893 vma_link_file(vma);
2894
2895 /*
2896 * vma_merge() calls khugepaged_enter_vma() either, the below
2897 * call covers the non-merge case.
2898 */
2899 khugepaged_enter_vma(vma, vma->vm_flags);
2900
2901 /* Once vma denies write, undo our temporary denial count */
2902unmap_writable:
2903 if (writable_file_mapping)
2904 mapping_unmap_writable(file->f_mapping);
2905 file = vma->vm_file;
2906 ksm_add_vma(vma);
2907expanded:
2908 perf_event_mmap(vma);
2909
2910 vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
2911 if (vm_flags & VM_LOCKED) {
2912 if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) ||
2913 is_vm_hugetlb_page(vma) ||
2914 vma == get_gate_vma(current->mm))
2915 vm_flags_clear(vma, VM_LOCKED_MASK);
2916 else
2917 mm->locked_vm += (len >> PAGE_SHIFT);
2918 }
2919
2920 if (file)
2921 uprobe_mmap(vma);
2922
2923 /*
2924 * New (or expanded) vma always get soft dirty status.
2925 * Otherwise user-space soft-dirty page tracker won't
2926 * be able to distinguish situation when vma area unmapped,
2927 * then new mapped in-place (which must be aimed as
2928 * a completely new data area).
2929 */
2930 vm_flags_set(vma, VM_SOFTDIRTY);
2931
2932 vma_set_page_prot(vma);
2933
2934 validate_mm(mm);
2935 return addr;
2936
2937close_and_free_vma:
2938 if (file && vma->vm_ops && vma->vm_ops->close)
2939 vma->vm_ops->close(vma);
2940
2941 if (file || vma->vm_file) {
2942unmap_and_free_vma:
2943 fput(vma->vm_file);
2944 vma->vm_file = NULL;
2945
2946 vma_iter_set(&vmi, vma->vm_end);
2947 /* Undo any partial mapping done by a device driver. */
2948 unmap_region(mm, &vmi.mas, vma, prev, next, vma->vm_start,
2949 vma->vm_end, vma->vm_end, true);
2950 }
2951 if (writable_file_mapping)
2952 mapping_unmap_writable(file->f_mapping);
2953free_vma:
2954 vm_area_free(vma);
2955unacct_error:
2956 if (charged)
2957 vm_unacct_memory(charged);
2958 validate_mm(mm);
2959 return error;
2960}
2961
2962static int __vm_munmap(unsigned long start, size_t len, bool unlock)
2963{
2964 int ret;
2965 struct mm_struct *mm = current->mm;
2966 LIST_HEAD(uf);
2967 VMA_ITERATOR(vmi, mm, start);
2968
2969 if (mmap_write_lock_killable(mm))
2970 return -EINTR;
2971
2972 ret = do_vmi_munmap(&vmi, mm, start, len, &uf, unlock);
2973 if (ret || !unlock)
2974 mmap_write_unlock(mm);
2975
2976 userfaultfd_unmap_complete(mm, &uf);
2977 return ret;
2978}
2979
2980int vm_munmap(unsigned long start, size_t len)
2981{
2982 return __vm_munmap(start, len, false);
2983}
2984EXPORT_SYMBOL(vm_munmap);
2985
2986SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2987{
2988 addr = untagged_addr(addr);
2989 return __vm_munmap(addr, len, true);
2990}
2991
2992
2993/*
2994 * Emulation of deprecated remap_file_pages() syscall.
2995 */
2996SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
2997 unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
2998{
2999
3000 struct mm_struct *mm = current->mm;
3001 struct vm_area_struct *vma;
3002 unsigned long populate = 0;
3003 unsigned long ret = -EINVAL;
3004 struct file *file;
3005
3006 pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/mm/remap_file_pages.rst.\n",
3007 current->comm, current->pid);
3008
3009 if (prot)
3010 return ret;
3011 start = start & PAGE_MASK;
3012 size = size & PAGE_MASK;
3013
3014 if (start + size <= start)
3015 return ret;
3016
3017 /* Does pgoff wrap? */
3018 if (pgoff + (size >> PAGE_SHIFT) < pgoff)
3019 return ret;
3020
3021 if (mmap_write_lock_killable(mm))
3022 return -EINTR;
3023
3024 vma = vma_lookup(mm, start);
3025
3026 if (!vma || !(vma->vm_flags & VM_SHARED))
3027 goto out;
3028
3029 if (start + size > vma->vm_end) {
3030 VMA_ITERATOR(vmi, mm, vma->vm_end);
3031 struct vm_area_struct *next, *prev = vma;
3032
3033 for_each_vma_range(vmi, next, start + size) {
3034 /* hole between vmas ? */
3035 if (next->vm_start != prev->vm_end)
3036 goto out;
3037
3038 if (next->vm_file != vma->vm_file)
3039 goto out;
3040
3041 if (next->vm_flags != vma->vm_flags)
3042 goto out;
3043
3044 if (start + size <= next->vm_end)
3045 break;
3046
3047 prev = next;
3048 }
3049
3050 if (!next)
3051 goto out;
3052 }
3053
3054 prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
3055 prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
3056 prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
3057
3058 flags &= MAP_NONBLOCK;
3059 flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
3060 if (vma->vm_flags & VM_LOCKED)
3061 flags |= MAP_LOCKED;
3062
3063 file = get_file(vma->vm_file);
3064 ret = do_mmap(vma->vm_file, start, size,
3065 prot, flags, 0, pgoff, &populate, NULL);
3066 fput(file);
3067out:
3068 mmap_write_unlock(mm);
3069 if (populate)
3070 mm_populate(ret, populate);
3071 if (!IS_ERR_VALUE(ret))
3072 ret = 0;
3073 return ret;
3074}
3075
3076/*
3077 * do_vma_munmap() - Unmap a full or partial vma.
3078 * @vmi: The vma iterator pointing at the vma
3079 * @vma: The first vma to be munmapped
3080 * @start: the start of the address to unmap
3081 * @end: The end of the address to unmap
3082 * @uf: The userfaultfd list_head
3083 * @unlock: Drop the lock on success
3084 *
3085 * unmaps a VMA mapping when the vma iterator is already in position.
3086 * Does not handle alignment.
3087 *
3088 * Return: 0 on success drops the lock of so directed, error on failure and will
3089 * still hold the lock.
3090 */
3091int do_vma_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
3092 unsigned long start, unsigned long end, struct list_head *uf,
3093 bool unlock)
3094{
3095 struct mm_struct *mm = vma->vm_mm;
3096
3097 arch_unmap(mm, start, end);
3098 return do_vmi_align_munmap(vmi, vma, mm, start, end, uf, unlock);
3099}
3100
3101/*
3102 * do_brk_flags() - Increase the brk vma if the flags match.
3103 * @vmi: The vma iterator
3104 * @addr: The start address
3105 * @len: The length of the increase
3106 * @vma: The vma,
3107 * @flags: The VMA Flags
3108 *
3109 * Extend the brk VMA from addr to addr + len. If the VMA is NULL or the flags
3110 * do not match then create a new anonymous VMA. Eventually we may be able to
3111 * do some brk-specific accounting here.
3112 */
3113static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
3114 unsigned long addr, unsigned long len, unsigned long flags)
3115{
3116 struct mm_struct *mm = current->mm;
3117 struct vma_prepare vp;
3118
3119 /*
3120 * Check against address space limits by the changed size
3121 * Note: This happens *after* clearing old mappings in some code paths.
3122 */
3123 flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
3124 if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))
3125 return -ENOMEM;
3126
3127 if (mm->map_count > sysctl_max_map_count)
3128 return -ENOMEM;
3129
3130 if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
3131 return -ENOMEM;
3132
3133 /*
3134 * Expand the existing vma if possible; Note that singular lists do not
3135 * occur after forking, so the expand will only happen on new VMAs.
3136 */
3137 if (vma && vma->vm_end == addr && !vma_policy(vma) &&
3138 can_vma_merge_after(vma, flags, NULL, NULL,
3139 addr >> PAGE_SHIFT, NULL_VM_UFFD_CTX, NULL)) {
3140 vma_iter_config(vmi, vma->vm_start, addr + len);
3141 if (vma_iter_prealloc(vmi, vma))
3142 goto unacct_fail;
3143
3144 vma_start_write(vma);
3145
3146 init_vma_prep(&vp, vma);
3147 vma_prepare(&vp);
3148 vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0);
3149 vma->vm_end = addr + len;
3150 vm_flags_set(vma, VM_SOFTDIRTY);
3151 vma_iter_store(vmi, vma);
3152
3153 vma_complete(&vp, vmi, mm);
3154 khugepaged_enter_vma(vma, flags);
3155 goto out;
3156 }
3157
3158 if (vma)
3159 vma_iter_next_range(vmi);
3160 /* create a vma struct for an anonymous mapping */
3161 vma = vm_area_alloc(mm);
3162 if (!vma)
3163 goto unacct_fail;
3164
3165 vma_set_anonymous(vma);
3166 vma_set_range(vma, addr, addr + len, addr >> PAGE_SHIFT);
3167 vm_flags_init(vma, flags);
3168 vma->vm_page_prot = vm_get_page_prot(flags);
3169 vma_start_write(vma);
3170 if (vma_iter_store_gfp(vmi, vma, GFP_KERNEL))
3171 goto mas_store_fail;
3172
3173 mm->map_count++;
3174 validate_mm(mm);
3175 ksm_add_vma(vma);
3176out:
3177 perf_event_mmap(vma);
3178 mm->total_vm += len >> PAGE_SHIFT;
3179 mm->data_vm += len >> PAGE_SHIFT;
3180 if (flags & VM_LOCKED)
3181 mm->locked_vm += (len >> PAGE_SHIFT);
3182 vm_flags_set(vma, VM_SOFTDIRTY);
3183 return 0;
3184
3185mas_store_fail:
3186 vm_area_free(vma);
3187unacct_fail:
3188 vm_unacct_memory(len >> PAGE_SHIFT);
3189 return -ENOMEM;
3190}
3191
3192int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
3193{
3194 struct mm_struct *mm = current->mm;
3195 struct vm_area_struct *vma = NULL;
3196 unsigned long len;
3197 int ret;
3198 bool populate;
3199 LIST_HEAD(uf);
3200 VMA_ITERATOR(vmi, mm, addr);
3201
3202 len = PAGE_ALIGN(request);
3203 if (len < request)
3204 return -ENOMEM;
3205 if (!len)
3206 return 0;
3207
3208 /* Until we need other flags, refuse anything except VM_EXEC. */
3209 if ((flags & (~VM_EXEC)) != 0)
3210 return -EINVAL;
3211
3212 if (mmap_write_lock_killable(mm))
3213 return -EINTR;
3214
3215 ret = check_brk_limits(addr, len);
3216 if (ret)
3217 goto limits_failed;
3218
3219 ret = do_vmi_munmap(&vmi, mm, addr, len, &uf, 0);
3220 if (ret)
3221 goto munmap_failed;
3222
3223 vma = vma_prev(&vmi);
3224 ret = do_brk_flags(&vmi, vma, addr, len, flags);
3225 populate = ((mm->def_flags & VM_LOCKED) != 0);
3226 mmap_write_unlock(mm);
3227 userfaultfd_unmap_complete(mm, &uf);
3228 if (populate && !ret)
3229 mm_populate(addr, len);
3230 return ret;
3231
3232munmap_failed:
3233limits_failed:
3234 mmap_write_unlock(mm);
3235 return ret;
3236}
3237EXPORT_SYMBOL(vm_brk_flags);
3238
3239/* Release all mmaps. */
3240void exit_mmap(struct mm_struct *mm)
3241{
3242 struct mmu_gather tlb;
3243 struct vm_area_struct *vma;
3244 unsigned long nr_accounted = 0;
3245 MA_STATE(mas, &mm->mm_mt, 0, 0);
3246 int count = 0;
3247
3248 /* mm's last user has gone, and its about to be pulled down */
3249 mmu_notifier_release(mm);
3250
3251 mmap_read_lock(mm);
3252 arch_exit_mmap(mm);
3253
3254 vma = mas_find(&mas, ULONG_MAX);
3255 if (!vma || unlikely(xa_is_zero(vma))) {
3256 /* Can happen if dup_mmap() received an OOM */
3257 mmap_read_unlock(mm);
3258 mmap_write_lock(mm);
3259 goto destroy;
3260 }
3261
3262 lru_add_drain();
3263 flush_cache_mm(mm);
3264 tlb_gather_mmu_fullmm(&tlb, mm);
3265 /* update_hiwater_rss(mm) here? but nobody should be looking */
3266 /* Use ULONG_MAX here to ensure all VMAs in the mm are unmapped */
3267 unmap_vmas(&tlb, &mas, vma, 0, ULONG_MAX, ULONG_MAX, false);
3268 mmap_read_unlock(mm);
3269
3270 /*
3271 * Set MMF_OOM_SKIP to hide this task from the oom killer/reaper
3272 * because the memory has been already freed.
3273 */
3274 set_bit(MMF_OOM_SKIP, &mm->flags);
3275 mmap_write_lock(mm);
3276 mt_clear_in_rcu(&mm->mm_mt);
3277 mas_set(&mas, vma->vm_end);
3278 free_pgtables(&tlb, &mas, vma, FIRST_USER_ADDRESS,
3279 USER_PGTABLES_CEILING, true);
3280 tlb_finish_mmu(&tlb);
3281
3282 /*
3283 * Walk the list again, actually closing and freeing it, with preemption
3284 * enabled, without holding any MM locks besides the unreachable
3285 * mmap_write_lock.
3286 */
3287 mas_set(&mas, vma->vm_end);
3288 do {
3289 if (vma->vm_flags & VM_ACCOUNT)
3290 nr_accounted += vma_pages(vma);
3291 remove_vma(vma, true);
3292 count++;
3293 cond_resched();
3294 vma = mas_find(&mas, ULONG_MAX);
3295 } while (vma && likely(!xa_is_zero(vma)));
3296
3297 BUG_ON(count != mm->map_count);
3298
3299 trace_exit_mmap(mm);
3300destroy:
3301 __mt_destroy(&mm->mm_mt);
3302 mmap_write_unlock(mm);
3303 vm_unacct_memory(nr_accounted);
3304}
3305
3306/* Insert vm structure into process list sorted by address
3307 * and into the inode's i_mmap tree. If vm_file is non-NULL
3308 * then i_mmap_rwsem is taken here.
3309 */
3310int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
3311{
3312 unsigned long charged = vma_pages(vma);
3313
3314
3315 if (find_vma_intersection(mm, vma->vm_start, vma->vm_end))
3316 return -ENOMEM;
3317
3318 if ((vma->vm_flags & VM_ACCOUNT) &&
3319 security_vm_enough_memory_mm(mm, charged))
3320 return -ENOMEM;
3321
3322 /*
3323 * The vm_pgoff of a purely anonymous vma should be irrelevant
3324 * until its first write fault, when page's anon_vma and index
3325 * are set. But now set the vm_pgoff it will almost certainly
3326 * end up with (unless mremap moves it elsewhere before that
3327 * first wfault), so /proc/pid/maps tells a consistent story.
3328 *
3329 * By setting it to reflect the virtual start address of the
3330 * vma, merges and splits can happen in a seamless way, just
3331 * using the existing file pgoff checks and manipulations.
3332 * Similarly in do_mmap and in do_brk_flags.
3333 */
3334 if (vma_is_anonymous(vma)) {
3335 BUG_ON(vma->anon_vma);
3336 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
3337 }
3338
3339 if (vma_link(mm, vma)) {
3340 if (vma->vm_flags & VM_ACCOUNT)
3341 vm_unacct_memory(charged);
3342 return -ENOMEM;
3343 }
3344
3345 return 0;
3346}
3347
3348/*
3349 * Copy the vma structure to a new location in the same mm,
3350 * prior to moving page table entries, to effect an mremap move.
3351 */
3352struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
3353 unsigned long addr, unsigned long len, pgoff_t pgoff,
3354 bool *need_rmap_locks)
3355{
3356 struct vm_area_struct *vma = *vmap;
3357 unsigned long vma_start = vma->vm_start;
3358 struct mm_struct *mm = vma->vm_mm;
3359 struct vm_area_struct *new_vma, *prev;
3360 bool faulted_in_anon_vma = true;
3361 VMA_ITERATOR(vmi, mm, addr);
3362
3363 /*
3364 * If anonymous vma has not yet been faulted, update new pgoff
3365 * to match new location, to increase its chance of merging.
3366 */
3367 if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
3368 pgoff = addr >> PAGE_SHIFT;
3369 faulted_in_anon_vma = false;
3370 }
3371
3372 new_vma = find_vma_prev(mm, addr, &prev);
3373 if (new_vma && new_vma->vm_start < addr + len)
3374 return NULL; /* should never get here */
3375
3376 new_vma = vma_merge_new_vma(&vmi, prev, vma, addr, addr + len, pgoff);
3377 if (new_vma) {
3378 /*
3379 * Source vma may have been merged into new_vma
3380 */
3381 if (unlikely(vma_start >= new_vma->vm_start &&
3382 vma_start < new_vma->vm_end)) {
3383 /*
3384 * The only way we can get a vma_merge with
3385 * self during an mremap is if the vma hasn't
3386 * been faulted in yet and we were allowed to
3387 * reset the dst vma->vm_pgoff to the
3388 * destination address of the mremap to allow
3389 * the merge to happen. mremap must change the
3390 * vm_pgoff linearity between src and dst vmas
3391 * (in turn preventing a vma_merge) to be
3392 * safe. It is only safe to keep the vm_pgoff
3393 * linear if there are no pages mapped yet.
3394 */
3395 VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
3396 *vmap = vma = new_vma;
3397 }
3398 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
3399 } else {
3400 new_vma = vm_area_dup(vma);
3401 if (!new_vma)
3402 goto out;
3403 vma_set_range(new_vma, addr, addr + len, pgoff);
3404 if (vma_dup_policy(vma, new_vma))
3405 goto out_free_vma;
3406 if (anon_vma_clone(new_vma, vma))
3407 goto out_free_mempol;
3408 if (new_vma->vm_file)
3409 get_file(new_vma->vm_file);
3410 if (new_vma->vm_ops && new_vma->vm_ops->open)
3411 new_vma->vm_ops->open(new_vma);
3412 if (vma_link(mm, new_vma))
3413 goto out_vma_link;
3414 *need_rmap_locks = false;
3415 }
3416 return new_vma;
3417
3418out_vma_link:
3419 if (new_vma->vm_ops && new_vma->vm_ops->close)
3420 new_vma->vm_ops->close(new_vma);
3421
3422 if (new_vma->vm_file)
3423 fput(new_vma->vm_file);
3424
3425 unlink_anon_vmas(new_vma);
3426out_free_mempol:
3427 mpol_put(vma_policy(new_vma));
3428out_free_vma:
3429 vm_area_free(new_vma);
3430out:
3431 return NULL;
3432}
3433
3434/*
3435 * Return true if the calling process may expand its vm space by the passed
3436 * number of pages
3437 */
3438bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
3439{
3440 if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
3441 return false;
3442
3443 if (is_data_mapping(flags) &&
3444 mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
3445 /* Workaround for Valgrind */
3446 if (rlimit(RLIMIT_DATA) == 0 &&
3447 mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
3448 return true;
3449
3450 pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n",
3451 current->comm, current->pid,
3452 (mm->data_vm + npages) << PAGE_SHIFT,
3453 rlimit(RLIMIT_DATA),
3454 ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data");
3455
3456 if (!ignore_rlimit_data)
3457 return false;
3458 }
3459
3460 return true;
3461}
3462
3463void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
3464{
3465 WRITE_ONCE(mm->total_vm, READ_ONCE(mm->total_vm)+npages);
3466
3467 if (is_exec_mapping(flags))
3468 mm->exec_vm += npages;
3469 else if (is_stack_mapping(flags))
3470 mm->stack_vm += npages;
3471 else if (is_data_mapping(flags))
3472 mm->data_vm += npages;
3473}
3474
3475static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
3476
3477/*
3478 * Having a close hook prevents vma merging regardless of flags.
3479 */
3480static void special_mapping_close(struct vm_area_struct *vma)
3481{
3482}
3483
3484static const char *special_mapping_name(struct vm_area_struct *vma)
3485{
3486 return ((struct vm_special_mapping *)vma->vm_private_data)->name;
3487}
3488
3489static int special_mapping_mremap(struct vm_area_struct *new_vma)
3490{
3491 struct vm_special_mapping *sm = new_vma->vm_private_data;
3492
3493 if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
3494 return -EFAULT;
3495
3496 if (sm->mremap)
3497 return sm->mremap(sm, new_vma);
3498
3499 return 0;
3500}
3501
3502static int special_mapping_split(struct vm_area_struct *vma, unsigned long addr)
3503{
3504 /*
3505 * Forbid splitting special mappings - kernel has expectations over
3506 * the number of pages in mapping. Together with VM_DONTEXPAND
3507 * the size of vma should stay the same over the special mapping's
3508 * lifetime.
3509 */
3510 return -EINVAL;
3511}
3512
3513static const struct vm_operations_struct special_mapping_vmops = {
3514 .close = special_mapping_close,
3515 .fault = special_mapping_fault,
3516 .mremap = special_mapping_mremap,
3517 .name = special_mapping_name,
3518 /* vDSO code relies that VVAR can't be accessed remotely */
3519 .access = NULL,
3520 .may_split = special_mapping_split,
3521};
3522
3523static const struct vm_operations_struct legacy_special_mapping_vmops = {
3524 .close = special_mapping_close,
3525 .fault = special_mapping_fault,
3526};
3527
3528static vm_fault_t special_mapping_fault(struct vm_fault *vmf)
3529{
3530 struct vm_area_struct *vma = vmf->vma;
3531 pgoff_t pgoff;
3532 struct page **pages;
3533
3534 if (vma->vm_ops == &legacy_special_mapping_vmops) {
3535 pages = vma->vm_private_data;
3536 } else {
3537 struct vm_special_mapping *sm = vma->vm_private_data;
3538
3539 if (sm->fault)
3540 return sm->fault(sm, vmf->vma, vmf);
3541
3542 pages = sm->pages;
3543 }
3544
3545 for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
3546 pgoff--;
3547
3548 if (*pages) {
3549 struct page *page = *pages;
3550 get_page(page);
3551 vmf->page = page;
3552 return 0;
3553 }
3554
3555 return VM_FAULT_SIGBUS;
3556}
3557
3558static struct vm_area_struct *__install_special_mapping(
3559 struct mm_struct *mm,
3560 unsigned long addr, unsigned long len,
3561 unsigned long vm_flags, void *priv,
3562 const struct vm_operations_struct *ops)
3563{
3564 int ret;
3565 struct vm_area_struct *vma;
3566
3567 vma = vm_area_alloc(mm);
3568 if (unlikely(vma == NULL))
3569 return ERR_PTR(-ENOMEM);
3570
3571 vma_set_range(vma, addr, addr + len, 0);
3572 vm_flags_init(vma, (vm_flags | mm->def_flags |
3573 VM_DONTEXPAND | VM_SOFTDIRTY) & ~VM_LOCKED_MASK);
3574 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
3575
3576 vma->vm_ops = ops;
3577 vma->vm_private_data = priv;
3578
3579 ret = insert_vm_struct(mm, vma);
3580 if (ret)
3581 goto out;
3582
3583 vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
3584
3585 perf_event_mmap(vma);
3586
3587 return vma;
3588
3589out:
3590 vm_area_free(vma);
3591 return ERR_PTR(ret);
3592}
3593
3594bool vma_is_special_mapping(const struct vm_area_struct *vma,
3595 const struct vm_special_mapping *sm)
3596{
3597 return vma->vm_private_data == sm &&
3598 (vma->vm_ops == &special_mapping_vmops ||
3599 vma->vm_ops == &legacy_special_mapping_vmops);
3600}
3601
3602/*
3603 * Called with mm->mmap_lock held for writing.
3604 * Insert a new vma covering the given region, with the given flags.
3605 * Its pages are supplied by the given array of struct page *.
3606 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
3607 * The region past the last page supplied will always produce SIGBUS.
3608 * The array pointer and the pages it points to are assumed to stay alive
3609 * for as long as this mapping might exist.
3610 */
3611struct vm_area_struct *_install_special_mapping(
3612 struct mm_struct *mm,
3613 unsigned long addr, unsigned long len,
3614 unsigned long vm_flags, const struct vm_special_mapping *spec)
3615{
3616 return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
3617 &special_mapping_vmops);
3618}
3619
3620int install_special_mapping(struct mm_struct *mm,
3621 unsigned long addr, unsigned long len,
3622 unsigned long vm_flags, struct page **pages)
3623{
3624 struct vm_area_struct *vma = __install_special_mapping(
3625 mm, addr, len, vm_flags, (void *)pages,
3626 &legacy_special_mapping_vmops);
3627
3628 return PTR_ERR_OR_ZERO(vma);
3629}
3630
3631static DEFINE_MUTEX(mm_all_locks_mutex);
3632
3633static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
3634{
3635 if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
3636 /*
3637 * The LSB of head.next can't change from under us
3638 * because we hold the mm_all_locks_mutex.
3639 */
3640 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_lock);
3641 /*
3642 * We can safely modify head.next after taking the
3643 * anon_vma->root->rwsem. If some other vma in this mm shares
3644 * the same anon_vma we won't take it again.
3645 *
3646 * No need of atomic instructions here, head.next
3647 * can't change from under us thanks to the
3648 * anon_vma->root->rwsem.
3649 */
3650 if (__test_and_set_bit(0, (unsigned long *)
3651 &anon_vma->root->rb_root.rb_root.rb_node))
3652 BUG();
3653 }
3654}
3655
3656static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
3657{
3658 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3659 /*
3660 * AS_MM_ALL_LOCKS can't change from under us because
3661 * we hold the mm_all_locks_mutex.
3662 *
3663 * Operations on ->flags have to be atomic because
3664 * even if AS_MM_ALL_LOCKS is stable thanks to the
3665 * mm_all_locks_mutex, there may be other cpus
3666 * changing other bitflags in parallel to us.
3667 */
3668 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
3669 BUG();
3670 down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_lock);
3671 }
3672}
3673
3674/*
3675 * This operation locks against the VM for all pte/vma/mm related
3676 * operations that could ever happen on a certain mm. This includes
3677 * vmtruncate, try_to_unmap, and all page faults.
3678 *
3679 * The caller must take the mmap_lock in write mode before calling
3680 * mm_take_all_locks(). The caller isn't allowed to release the
3681 * mmap_lock until mm_drop_all_locks() returns.
3682 *
3683 * mmap_lock in write mode is required in order to block all operations
3684 * that could modify pagetables and free pages without need of
3685 * altering the vma layout. It's also needed in write mode to avoid new
3686 * anon_vmas to be associated with existing vmas.
3687 *
3688 * A single task can't take more than one mm_take_all_locks() in a row
3689 * or it would deadlock.
3690 *
3691 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3692 * mapping->flags avoid to take the same lock twice, if more than one
3693 * vma in this mm is backed by the same anon_vma or address_space.
3694 *
3695 * We take locks in following order, accordingly to comment at beginning
3696 * of mm/rmap.c:
3697 * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
3698 * hugetlb mapping);
3699 * - all vmas marked locked
3700 * - all i_mmap_rwsem locks;
3701 * - all anon_vma->rwseml
3702 *
3703 * We can take all locks within these types randomly because the VM code
3704 * doesn't nest them and we protected from parallel mm_take_all_locks() by
3705 * mm_all_locks_mutex.
3706 *
3707 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3708 * that may have to take thousand of locks.
3709 *
3710 * mm_take_all_locks() can fail if it's interrupted by signals.
3711 */
3712int mm_take_all_locks(struct mm_struct *mm)
3713{
3714 struct vm_area_struct *vma;
3715 struct anon_vma_chain *avc;
3716 MA_STATE(mas, &mm->mm_mt, 0, 0);
3717
3718 mmap_assert_write_locked(mm);
3719
3720 mutex_lock(&mm_all_locks_mutex);
3721
3722 /*
3723 * vma_start_write() does not have a complement in mm_drop_all_locks()
3724 * because vma_start_write() is always asymmetrical; it marks a VMA as
3725 * being written to until mmap_write_unlock() or mmap_write_downgrade()
3726 * is reached.
3727 */
3728 mas_for_each(&mas, vma, ULONG_MAX) {
3729 if (signal_pending(current))
3730 goto out_unlock;
3731 vma_start_write(vma);
3732 }
3733
3734 mas_set(&mas, 0);
3735 mas_for_each(&mas, vma, ULONG_MAX) {
3736 if (signal_pending(current))
3737 goto out_unlock;
3738 if (vma->vm_file && vma->vm_file->f_mapping &&
3739 is_vm_hugetlb_page(vma))
3740 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3741 }
3742
3743 mas_set(&mas, 0);
3744 mas_for_each(&mas, vma, ULONG_MAX) {
3745 if (signal_pending(current))
3746 goto out_unlock;
3747 if (vma->vm_file && vma->vm_file->f_mapping &&
3748 !is_vm_hugetlb_page(vma))
3749 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3750 }
3751
3752 mas_set(&mas, 0);
3753 mas_for_each(&mas, vma, ULONG_MAX) {
3754 if (signal_pending(current))
3755 goto out_unlock;
3756 if (vma->anon_vma)
3757 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3758 vm_lock_anon_vma(mm, avc->anon_vma);
3759 }
3760
3761 return 0;
3762
3763out_unlock:
3764 mm_drop_all_locks(mm);
3765 return -EINTR;
3766}
3767
3768static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3769{
3770 if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
3771 /*
3772 * The LSB of head.next can't change to 0 from under
3773 * us because we hold the mm_all_locks_mutex.
3774 *
3775 * We must however clear the bitflag before unlocking
3776 * the vma so the users using the anon_vma->rb_root will
3777 * never see our bitflag.
3778 *
3779 * No need of atomic instructions here, head.next
3780 * can't change from under us until we release the
3781 * anon_vma->root->rwsem.
3782 */
3783 if (!__test_and_clear_bit(0, (unsigned long *)
3784 &anon_vma->root->rb_root.rb_root.rb_node))
3785 BUG();
3786 anon_vma_unlock_write(anon_vma);
3787 }
3788}
3789
3790static void vm_unlock_mapping(struct address_space *mapping)
3791{
3792 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3793 /*
3794 * AS_MM_ALL_LOCKS can't change to 0 from under us
3795 * because we hold the mm_all_locks_mutex.
3796 */
3797 i_mmap_unlock_write(mapping);
3798 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
3799 &mapping->flags))
3800 BUG();
3801 }
3802}
3803
3804/*
3805 * The mmap_lock cannot be released by the caller until
3806 * mm_drop_all_locks() returns.
3807 */
3808void mm_drop_all_locks(struct mm_struct *mm)
3809{
3810 struct vm_area_struct *vma;
3811 struct anon_vma_chain *avc;
3812 MA_STATE(mas, &mm->mm_mt, 0, 0);
3813
3814 mmap_assert_write_locked(mm);
3815 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3816
3817 mas_for_each(&mas, vma, ULONG_MAX) {
3818 if (vma->anon_vma)
3819 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3820 vm_unlock_anon_vma(avc->anon_vma);
3821 if (vma->vm_file && vma->vm_file->f_mapping)
3822 vm_unlock_mapping(vma->vm_file->f_mapping);
3823 }
3824
3825 mutex_unlock(&mm_all_locks_mutex);
3826}
3827
3828/*
3829 * initialise the percpu counter for VM
3830 */
3831void __init mmap_init(void)
3832{
3833 int ret;
3834
3835 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
3836 VM_BUG_ON(ret);
3837}
3838
3839/*
3840 * Initialise sysctl_user_reserve_kbytes.
3841 *
3842 * This is intended to prevent a user from starting a single memory hogging
3843 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3844 * mode.
3845 *
3846 * The default value is min(3% of free memory, 128MB)
3847 * 128MB is enough to recover with sshd/login, bash, and top/kill.
3848 */
3849static int init_user_reserve(void)
3850{
3851 unsigned long free_kbytes;
3852
3853 free_kbytes = K(global_zone_page_state(NR_FREE_PAGES));
3854
3855 sysctl_user_reserve_kbytes = min(free_kbytes / 32, SZ_128K);
3856 return 0;
3857}
3858subsys_initcall(init_user_reserve);
3859
3860/*
3861 * Initialise sysctl_admin_reserve_kbytes.
3862 *
3863 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3864 * to log in and kill a memory hogging process.
3865 *
3866 * Systems with more than 256MB will reserve 8MB, enough to recover
3867 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3868 * only reserve 3% of free pages by default.
3869 */
3870static int init_admin_reserve(void)
3871{
3872 unsigned long free_kbytes;
3873
3874 free_kbytes = K(global_zone_page_state(NR_FREE_PAGES));
3875
3876 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, SZ_8K);
3877 return 0;
3878}
3879subsys_initcall(init_admin_reserve);
3880
3881/*
3882 * Reinititalise user and admin reserves if memory is added or removed.
3883 *
3884 * The default user reserve max is 128MB, and the default max for the
3885 * admin reserve is 8MB. These are usually, but not always, enough to
3886 * enable recovery from a memory hogging process using login/sshd, a shell,
3887 * and tools like top. It may make sense to increase or even disable the
3888 * reserve depending on the existence of swap or variations in the recovery
3889 * tools. So, the admin may have changed them.
3890 *
3891 * If memory is added and the reserves have been eliminated or increased above
3892 * the default max, then we'll trust the admin.
3893 *
3894 * If memory is removed and there isn't enough free memory, then we
3895 * need to reset the reserves.
3896 *
3897 * Otherwise keep the reserve set by the admin.
3898 */
3899static int reserve_mem_notifier(struct notifier_block *nb,
3900 unsigned long action, void *data)
3901{
3902 unsigned long tmp, free_kbytes;
3903
3904 switch (action) {
3905 case MEM_ONLINE:
3906 /* Default max is 128MB. Leave alone if modified by operator. */
3907 tmp = sysctl_user_reserve_kbytes;
3908 if (tmp > 0 && tmp < SZ_128K)
3909 init_user_reserve();
3910
3911 /* Default max is 8MB. Leave alone if modified by operator. */
3912 tmp = sysctl_admin_reserve_kbytes;
3913 if (tmp > 0 && tmp < SZ_8K)
3914 init_admin_reserve();
3915
3916 break;
3917 case MEM_OFFLINE:
3918 free_kbytes = K(global_zone_page_state(NR_FREE_PAGES));
3919
3920 if (sysctl_user_reserve_kbytes > free_kbytes) {
3921 init_user_reserve();
3922 pr_info("vm.user_reserve_kbytes reset to %lu\n",
3923 sysctl_user_reserve_kbytes);
3924 }
3925
3926 if (sysctl_admin_reserve_kbytes > free_kbytes) {
3927 init_admin_reserve();
3928 pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3929 sysctl_admin_reserve_kbytes);
3930 }
3931 break;
3932 default:
3933 break;
3934 }
3935 return NOTIFY_OK;
3936}
3937
3938static int __meminit init_reserve_notifier(void)
3939{
3940 if (hotplug_memory_notifier(reserve_mem_notifier, DEFAULT_CALLBACK_PRI))
3941 pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3942
3943 return 0;
3944}
3945subsys_initcall(init_reserve_notifier);