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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/vmacache.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/rbtree_augmented.h>
42#include <linux/notifier.h>
43#include <linux/memory.h>
44#include <linux/printk.h>
45#include <linux/userfaultfd_k.h>
46#include <linux/moduleparam.h>
47#include <linux/pkeys.h>
48#include <linux/oom.h>
49#include <linux/sched/mm.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#include "internal.h"
57
58#ifndef arch_mmap_check
59#define arch_mmap_check(addr, len, flags) (0)
60#endif
61
62#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
63const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
64const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX;
65int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
66#endif
67#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
68const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
69const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
70int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
71#endif
72
73static bool ignore_rlimit_data;
74core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
75
76static void unmap_region(struct mm_struct *mm,
77 struct vm_area_struct *vma, struct vm_area_struct *prev,
78 unsigned long start, unsigned long end);
79
80/* description of effects of mapping type and prot in current implementation.
81 * this is due to the limited x86 page protection hardware. The expected
82 * behavior is in parens:
83 *
84 * map_type prot
85 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
86 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
87 * w: (no) no w: (no) no w: (yes) yes w: (no) no
88 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
89 *
90 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
91 * w: (no) no w: (no) no w: (copy) copy w: (no) no
92 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
93 *
94 * On arm64, PROT_EXEC has the following behaviour for both MAP_SHARED and
95 * MAP_PRIVATE:
96 * r: (no) no
97 * w: (no) no
98 * x: (yes) yes
99 */
100pgprot_t protection_map[16] __ro_after_init = {
101 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
102 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
103};
104
105#ifndef CONFIG_ARCH_HAS_FILTER_PGPROT
106static inline pgprot_t arch_filter_pgprot(pgprot_t prot)
107{
108 return prot;
109}
110#endif
111
112pgprot_t vm_get_page_prot(unsigned long vm_flags)
113{
114 pgprot_t ret = __pgprot(pgprot_val(protection_map[vm_flags &
115 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
116 pgprot_val(arch_vm_get_page_prot(vm_flags)));
117
118 return arch_filter_pgprot(ret);
119}
120EXPORT_SYMBOL(vm_get_page_prot);
121
122static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
123{
124 return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
125}
126
127/* Update vma->vm_page_prot to reflect vma->vm_flags. */
128void vma_set_page_prot(struct vm_area_struct *vma)
129{
130 unsigned long vm_flags = vma->vm_flags;
131 pgprot_t vm_page_prot;
132
133 vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
134 if (vma_wants_writenotify(vma, vm_page_prot)) {
135 vm_flags &= ~VM_SHARED;
136 vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags);
137 }
138 /* remove_protection_ptes reads vma->vm_page_prot without mmap_sem */
139 WRITE_ONCE(vma->vm_page_prot, vm_page_prot);
140}
141
142/*
143 * Requires inode->i_mapping->i_mmap_rwsem
144 */
145static void __remove_shared_vm_struct(struct vm_area_struct *vma,
146 struct file *file, struct address_space *mapping)
147{
148 if (vma->vm_flags & VM_DENYWRITE)
149 atomic_inc(&file_inode(file)->i_writecount);
150 if (vma->vm_flags & VM_SHARED)
151 mapping_unmap_writable(mapping);
152
153 flush_dcache_mmap_lock(mapping);
154 vma_interval_tree_remove(vma, &mapping->i_mmap);
155 flush_dcache_mmap_unlock(mapping);
156}
157
158/*
159 * Unlink a file-based vm structure from its interval tree, to hide
160 * vma from rmap and vmtruncate before freeing its page tables.
161 */
162void unlink_file_vma(struct vm_area_struct *vma)
163{
164 struct file *file = vma->vm_file;
165
166 if (file) {
167 struct address_space *mapping = file->f_mapping;
168 i_mmap_lock_write(mapping);
169 __remove_shared_vm_struct(vma, file, mapping);
170 i_mmap_unlock_write(mapping);
171 }
172}
173
174/*
175 * Close a vm structure and free it, returning the next.
176 */
177static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
178{
179 struct vm_area_struct *next = vma->vm_next;
180
181 might_sleep();
182 if (vma->vm_ops && vma->vm_ops->close)
183 vma->vm_ops->close(vma);
184 if (vma->vm_file)
185 fput(vma->vm_file);
186 mpol_put(vma_policy(vma));
187 vm_area_free(vma);
188 return next;
189}
190
191static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long flags,
192 struct list_head *uf);
193SYSCALL_DEFINE1(brk, unsigned long, brk)
194{
195 unsigned long retval;
196 unsigned long newbrk, oldbrk, origbrk;
197 struct mm_struct *mm = current->mm;
198 struct vm_area_struct *next;
199 unsigned long min_brk;
200 bool populate;
201 bool downgraded = false;
202 LIST_HEAD(uf);
203
204 brk = untagged_addr(brk);
205
206 if (down_write_killable(&mm->mmap_sem))
207 return -EINTR;
208
209 origbrk = mm->brk;
210
211#ifdef CONFIG_COMPAT_BRK
212 /*
213 * CONFIG_COMPAT_BRK can still be overridden by setting
214 * randomize_va_space to 2, which will still cause mm->start_brk
215 * to be arbitrarily shifted
216 */
217 if (current->brk_randomized)
218 min_brk = mm->start_brk;
219 else
220 min_brk = mm->end_data;
221#else
222 min_brk = mm->start_brk;
223#endif
224 if (brk < min_brk)
225 goto out;
226
227 /*
228 * Check against rlimit here. If this check is done later after the test
229 * of oldbrk with newbrk then it can escape the test and let the data
230 * segment grow beyond its set limit the in case where the limit is
231 * not page aligned -Ram Gupta
232 */
233 if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
234 mm->end_data, mm->start_data))
235 goto out;
236
237 newbrk = PAGE_ALIGN(brk);
238 oldbrk = PAGE_ALIGN(mm->brk);
239 if (oldbrk == newbrk) {
240 mm->brk = brk;
241 goto success;
242 }
243
244 /*
245 * Always allow shrinking brk.
246 * __do_munmap() may downgrade mmap_sem to read.
247 */
248 if (brk <= mm->brk) {
249 int ret;
250
251 /*
252 * mm->brk must to be protected by write mmap_sem so update it
253 * before downgrading mmap_sem. When __do_munmap() fails,
254 * mm->brk will be restored from origbrk.
255 */
256 mm->brk = brk;
257 ret = __do_munmap(mm, newbrk, oldbrk-newbrk, &uf, true);
258 if (ret < 0) {
259 mm->brk = origbrk;
260 goto out;
261 } else if (ret == 1) {
262 downgraded = true;
263 }
264 goto success;
265 }
266
267 /* Check against existing mmap mappings. */
268 next = find_vma(mm, oldbrk);
269 if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
270 goto out;
271
272 /* Ok, looks good - let it rip. */
273 if (do_brk_flags(oldbrk, newbrk-oldbrk, 0, &uf) < 0)
274 goto out;
275 mm->brk = brk;
276
277success:
278 populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
279 if (downgraded)
280 up_read(&mm->mmap_sem);
281 else
282 up_write(&mm->mmap_sem);
283 userfaultfd_unmap_complete(mm, &uf);
284 if (populate)
285 mm_populate(oldbrk, newbrk - oldbrk);
286 return brk;
287
288out:
289 retval = origbrk;
290 up_write(&mm->mmap_sem);
291 return retval;
292}
293
294static inline unsigned long vma_compute_gap(struct vm_area_struct *vma)
295{
296 unsigned long gap, prev_end;
297
298 /*
299 * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we
300 * allow two stack_guard_gaps between them here, and when choosing
301 * an unmapped area; whereas when expanding we only require one.
302 * That's a little inconsistent, but keeps the code here simpler.
303 */
304 gap = vm_start_gap(vma);
305 if (vma->vm_prev) {
306 prev_end = vm_end_gap(vma->vm_prev);
307 if (gap > prev_end)
308 gap -= prev_end;
309 else
310 gap = 0;
311 }
312 return gap;
313}
314
315#ifdef CONFIG_DEBUG_VM_RB
316static unsigned long vma_compute_subtree_gap(struct vm_area_struct *vma)
317{
318 unsigned long max = vma_compute_gap(vma), subtree_gap;
319 if (vma->vm_rb.rb_left) {
320 subtree_gap = rb_entry(vma->vm_rb.rb_left,
321 struct vm_area_struct, vm_rb)->rb_subtree_gap;
322 if (subtree_gap > max)
323 max = subtree_gap;
324 }
325 if (vma->vm_rb.rb_right) {
326 subtree_gap = rb_entry(vma->vm_rb.rb_right,
327 struct vm_area_struct, vm_rb)->rb_subtree_gap;
328 if (subtree_gap > max)
329 max = subtree_gap;
330 }
331 return max;
332}
333
334static int browse_rb(struct mm_struct *mm)
335{
336 struct rb_root *root = &mm->mm_rb;
337 int i = 0, j, bug = 0;
338 struct rb_node *nd, *pn = NULL;
339 unsigned long prev = 0, pend = 0;
340
341 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
342 struct vm_area_struct *vma;
343 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
344 if (vma->vm_start < prev) {
345 pr_emerg("vm_start %lx < prev %lx\n",
346 vma->vm_start, prev);
347 bug = 1;
348 }
349 if (vma->vm_start < pend) {
350 pr_emerg("vm_start %lx < pend %lx\n",
351 vma->vm_start, pend);
352 bug = 1;
353 }
354 if (vma->vm_start > vma->vm_end) {
355 pr_emerg("vm_start %lx > vm_end %lx\n",
356 vma->vm_start, vma->vm_end);
357 bug = 1;
358 }
359 spin_lock(&mm->page_table_lock);
360 if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
361 pr_emerg("free gap %lx, correct %lx\n",
362 vma->rb_subtree_gap,
363 vma_compute_subtree_gap(vma));
364 bug = 1;
365 }
366 spin_unlock(&mm->page_table_lock);
367 i++;
368 pn = nd;
369 prev = vma->vm_start;
370 pend = vma->vm_end;
371 }
372 j = 0;
373 for (nd = pn; nd; nd = rb_prev(nd))
374 j++;
375 if (i != j) {
376 pr_emerg("backwards %d, forwards %d\n", j, i);
377 bug = 1;
378 }
379 return bug ? -1 : i;
380}
381
382static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
383{
384 struct rb_node *nd;
385
386 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
387 struct vm_area_struct *vma;
388 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
389 VM_BUG_ON_VMA(vma != ignore &&
390 vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
391 vma);
392 }
393}
394
395static void validate_mm(struct mm_struct *mm)
396{
397 int bug = 0;
398 int i = 0;
399 unsigned long highest_address = 0;
400 struct vm_area_struct *vma = mm->mmap;
401
402 while (vma) {
403 struct anon_vma *anon_vma = vma->anon_vma;
404 struct anon_vma_chain *avc;
405
406 if (anon_vma) {
407 anon_vma_lock_read(anon_vma);
408 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
409 anon_vma_interval_tree_verify(avc);
410 anon_vma_unlock_read(anon_vma);
411 }
412
413 highest_address = vm_end_gap(vma);
414 vma = vma->vm_next;
415 i++;
416 }
417 if (i != mm->map_count) {
418 pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
419 bug = 1;
420 }
421 if (highest_address != mm->highest_vm_end) {
422 pr_emerg("mm->highest_vm_end %lx, found %lx\n",
423 mm->highest_vm_end, highest_address);
424 bug = 1;
425 }
426 i = browse_rb(mm);
427 if (i != mm->map_count) {
428 if (i != -1)
429 pr_emerg("map_count %d rb %d\n", mm->map_count, i);
430 bug = 1;
431 }
432 VM_BUG_ON_MM(bug, mm);
433}
434#else
435#define validate_mm_rb(root, ignore) do { } while (0)
436#define validate_mm(mm) do { } while (0)
437#endif
438
439RB_DECLARE_CALLBACKS_MAX(static, vma_gap_callbacks,
440 struct vm_area_struct, vm_rb,
441 unsigned long, rb_subtree_gap, vma_compute_gap)
442
443/*
444 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
445 * vma->vm_prev->vm_end values changed, without modifying the vma's position
446 * in the rbtree.
447 */
448static void vma_gap_update(struct vm_area_struct *vma)
449{
450 /*
451 * As it turns out, RB_DECLARE_CALLBACKS_MAX() already created
452 * a callback function that does exactly what we want.
453 */
454 vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
455}
456
457static inline void vma_rb_insert(struct vm_area_struct *vma,
458 struct rb_root *root)
459{
460 /* All rb_subtree_gap values must be consistent prior to insertion */
461 validate_mm_rb(root, NULL);
462
463 rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
464}
465
466static void __vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
467{
468 /*
469 * Note rb_erase_augmented is a fairly large inline function,
470 * so make sure we instantiate it only once with our desired
471 * augmented rbtree callbacks.
472 */
473 rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
474}
475
476static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma,
477 struct rb_root *root,
478 struct vm_area_struct *ignore)
479{
480 /*
481 * All rb_subtree_gap values must be consistent prior to erase,
482 * with the possible exception of the "next" vma being erased if
483 * next->vm_start was reduced.
484 */
485 validate_mm_rb(root, ignore);
486
487 __vma_rb_erase(vma, root);
488}
489
490static __always_inline void vma_rb_erase(struct vm_area_struct *vma,
491 struct rb_root *root)
492{
493 /*
494 * All rb_subtree_gap values must be consistent prior to erase,
495 * with the possible exception of the vma being erased.
496 */
497 validate_mm_rb(root, vma);
498
499 __vma_rb_erase(vma, root);
500}
501
502/*
503 * vma has some anon_vma assigned, and is already inserted on that
504 * anon_vma's interval trees.
505 *
506 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
507 * vma must be removed from the anon_vma's interval trees using
508 * anon_vma_interval_tree_pre_update_vma().
509 *
510 * After the update, the vma will be reinserted using
511 * anon_vma_interval_tree_post_update_vma().
512 *
513 * The entire update must be protected by exclusive mmap_sem and by
514 * the root anon_vma's mutex.
515 */
516static inline void
517anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
518{
519 struct anon_vma_chain *avc;
520
521 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
522 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
523}
524
525static inline void
526anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
527{
528 struct anon_vma_chain *avc;
529
530 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
531 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
532}
533
534static int find_vma_links(struct mm_struct *mm, unsigned long addr,
535 unsigned long end, struct vm_area_struct **pprev,
536 struct rb_node ***rb_link, struct rb_node **rb_parent)
537{
538 struct rb_node **__rb_link, *__rb_parent, *rb_prev;
539
540 __rb_link = &mm->mm_rb.rb_node;
541 rb_prev = __rb_parent = NULL;
542
543 while (*__rb_link) {
544 struct vm_area_struct *vma_tmp;
545
546 __rb_parent = *__rb_link;
547 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
548
549 if (vma_tmp->vm_end > addr) {
550 /* Fail if an existing vma overlaps the area */
551 if (vma_tmp->vm_start < end)
552 return -ENOMEM;
553 __rb_link = &__rb_parent->rb_left;
554 } else {
555 rb_prev = __rb_parent;
556 __rb_link = &__rb_parent->rb_right;
557 }
558 }
559
560 *pprev = NULL;
561 if (rb_prev)
562 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
563 *rb_link = __rb_link;
564 *rb_parent = __rb_parent;
565 return 0;
566}
567
568static unsigned long count_vma_pages_range(struct mm_struct *mm,
569 unsigned long addr, unsigned long end)
570{
571 unsigned long nr_pages = 0;
572 struct vm_area_struct *vma;
573
574 /* Find first overlaping mapping */
575 vma = find_vma_intersection(mm, addr, end);
576 if (!vma)
577 return 0;
578
579 nr_pages = (min(end, vma->vm_end) -
580 max(addr, vma->vm_start)) >> PAGE_SHIFT;
581
582 /* Iterate over the rest of the overlaps */
583 for (vma = vma->vm_next; vma; vma = vma->vm_next) {
584 unsigned long overlap_len;
585
586 if (vma->vm_start > end)
587 break;
588
589 overlap_len = min(end, vma->vm_end) - vma->vm_start;
590 nr_pages += overlap_len >> PAGE_SHIFT;
591 }
592
593 return nr_pages;
594}
595
596void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
597 struct rb_node **rb_link, struct rb_node *rb_parent)
598{
599 /* Update tracking information for the gap following the new vma. */
600 if (vma->vm_next)
601 vma_gap_update(vma->vm_next);
602 else
603 mm->highest_vm_end = vm_end_gap(vma);
604
605 /*
606 * vma->vm_prev wasn't known when we followed the rbtree to find the
607 * correct insertion point for that vma. As a result, we could not
608 * update the vma vm_rb parents rb_subtree_gap values on the way down.
609 * So, we first insert the vma with a zero rb_subtree_gap value
610 * (to be consistent with what we did on the way down), and then
611 * immediately update the gap to the correct value. Finally we
612 * rebalance the rbtree after all augmented values have been set.
613 */
614 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
615 vma->rb_subtree_gap = 0;
616 vma_gap_update(vma);
617 vma_rb_insert(vma, &mm->mm_rb);
618}
619
620static void __vma_link_file(struct vm_area_struct *vma)
621{
622 struct file *file;
623
624 file = vma->vm_file;
625 if (file) {
626 struct address_space *mapping = file->f_mapping;
627
628 if (vma->vm_flags & VM_DENYWRITE)
629 atomic_dec(&file_inode(file)->i_writecount);
630 if (vma->vm_flags & VM_SHARED)
631 atomic_inc(&mapping->i_mmap_writable);
632
633 flush_dcache_mmap_lock(mapping);
634 vma_interval_tree_insert(vma, &mapping->i_mmap);
635 flush_dcache_mmap_unlock(mapping);
636 }
637}
638
639static void
640__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
641 struct vm_area_struct *prev, struct rb_node **rb_link,
642 struct rb_node *rb_parent)
643{
644 __vma_link_list(mm, vma, prev, rb_parent);
645 __vma_link_rb(mm, vma, rb_link, rb_parent);
646}
647
648static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
649 struct vm_area_struct *prev, struct rb_node **rb_link,
650 struct rb_node *rb_parent)
651{
652 struct address_space *mapping = NULL;
653
654 if (vma->vm_file) {
655 mapping = vma->vm_file->f_mapping;
656 i_mmap_lock_write(mapping);
657 }
658
659 __vma_link(mm, vma, prev, rb_link, rb_parent);
660 __vma_link_file(vma);
661
662 if (mapping)
663 i_mmap_unlock_write(mapping);
664
665 mm->map_count++;
666 validate_mm(mm);
667}
668
669/*
670 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
671 * mm's list and rbtree. It has already been inserted into the interval tree.
672 */
673static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
674{
675 struct vm_area_struct *prev;
676 struct rb_node **rb_link, *rb_parent;
677
678 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
679 &prev, &rb_link, &rb_parent))
680 BUG();
681 __vma_link(mm, vma, prev, rb_link, rb_parent);
682 mm->map_count++;
683}
684
685static __always_inline void __vma_unlink_common(struct mm_struct *mm,
686 struct vm_area_struct *vma,
687 struct vm_area_struct *prev,
688 bool has_prev,
689 struct vm_area_struct *ignore)
690{
691 struct vm_area_struct *next;
692
693 vma_rb_erase_ignore(vma, &mm->mm_rb, ignore);
694 next = vma->vm_next;
695 if (has_prev)
696 prev->vm_next = next;
697 else {
698 prev = vma->vm_prev;
699 if (prev)
700 prev->vm_next = next;
701 else
702 mm->mmap = next;
703 }
704 if (next)
705 next->vm_prev = prev;
706
707 /* Kill the cache */
708 vmacache_invalidate(mm);
709}
710
711static inline void __vma_unlink_prev(struct mm_struct *mm,
712 struct vm_area_struct *vma,
713 struct vm_area_struct *prev)
714{
715 __vma_unlink_common(mm, vma, prev, true, vma);
716}
717
718/*
719 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
720 * is already present in an i_mmap tree without adjusting the tree.
721 * The following helper function should be used when such adjustments
722 * are necessary. The "insert" vma (if any) is to be inserted
723 * before we drop the necessary locks.
724 */
725int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
726 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert,
727 struct vm_area_struct *expand)
728{
729 struct mm_struct *mm = vma->vm_mm;
730 struct vm_area_struct *next = vma->vm_next, *orig_vma = vma;
731 struct address_space *mapping = NULL;
732 struct rb_root_cached *root = NULL;
733 struct anon_vma *anon_vma = NULL;
734 struct file *file = vma->vm_file;
735 bool start_changed = false, end_changed = false;
736 long adjust_next = 0;
737 int remove_next = 0;
738
739 if (next && !insert) {
740 struct vm_area_struct *exporter = NULL, *importer = NULL;
741
742 if (end >= next->vm_end) {
743 /*
744 * vma expands, overlapping all the next, and
745 * perhaps the one after too (mprotect case 6).
746 * The only other cases that gets here are
747 * case 1, case 7 and case 8.
748 */
749 if (next == expand) {
750 /*
751 * The only case where we don't expand "vma"
752 * and we expand "next" instead is case 8.
753 */
754 VM_WARN_ON(end != next->vm_end);
755 /*
756 * remove_next == 3 means we're
757 * removing "vma" and that to do so we
758 * swapped "vma" and "next".
759 */
760 remove_next = 3;
761 VM_WARN_ON(file != next->vm_file);
762 swap(vma, next);
763 } else {
764 VM_WARN_ON(expand != vma);
765 /*
766 * case 1, 6, 7, remove_next == 2 is case 6,
767 * remove_next == 1 is case 1 or 7.
768 */
769 remove_next = 1 + (end > next->vm_end);
770 VM_WARN_ON(remove_next == 2 &&
771 end != next->vm_next->vm_end);
772 VM_WARN_ON(remove_next == 1 &&
773 end != next->vm_end);
774 /* trim end to next, for case 6 first pass */
775 end = next->vm_end;
776 }
777
778 exporter = next;
779 importer = vma;
780
781 /*
782 * If next doesn't have anon_vma, import from vma after
783 * next, if the vma overlaps with it.
784 */
785 if (remove_next == 2 && !next->anon_vma)
786 exporter = next->vm_next;
787
788 } else if (end > next->vm_start) {
789 /*
790 * vma expands, overlapping part of the next:
791 * mprotect case 5 shifting the boundary up.
792 */
793 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
794 exporter = next;
795 importer = vma;
796 VM_WARN_ON(expand != importer);
797 } else if (end < vma->vm_end) {
798 /*
799 * vma shrinks, and !insert tells it's not
800 * split_vma inserting another: so it must be
801 * mprotect case 4 shifting the boundary down.
802 */
803 adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT);
804 exporter = vma;
805 importer = next;
806 VM_WARN_ON(expand != importer);
807 }
808
809 /*
810 * Easily overlooked: when mprotect shifts the boundary,
811 * make sure the expanding vma has anon_vma set if the
812 * shrinking vma had, to cover any anon pages imported.
813 */
814 if (exporter && exporter->anon_vma && !importer->anon_vma) {
815 int error;
816
817 importer->anon_vma = exporter->anon_vma;
818 error = anon_vma_clone(importer, exporter);
819 if (error)
820 return error;
821 }
822 }
823again:
824 vma_adjust_trans_huge(orig_vma, start, end, adjust_next);
825
826 if (file) {
827 mapping = file->f_mapping;
828 root = &mapping->i_mmap;
829 uprobe_munmap(vma, vma->vm_start, vma->vm_end);
830
831 if (adjust_next)
832 uprobe_munmap(next, next->vm_start, next->vm_end);
833
834 i_mmap_lock_write(mapping);
835 if (insert) {
836 /*
837 * Put into interval tree now, so instantiated pages
838 * are visible to arm/parisc __flush_dcache_page
839 * throughout; but we cannot insert into address
840 * space until vma start or end is updated.
841 */
842 __vma_link_file(insert);
843 }
844 }
845
846 anon_vma = vma->anon_vma;
847 if (!anon_vma && adjust_next)
848 anon_vma = next->anon_vma;
849 if (anon_vma) {
850 VM_WARN_ON(adjust_next && next->anon_vma &&
851 anon_vma != next->anon_vma);
852 anon_vma_lock_write(anon_vma);
853 anon_vma_interval_tree_pre_update_vma(vma);
854 if (adjust_next)
855 anon_vma_interval_tree_pre_update_vma(next);
856 }
857
858 if (root) {
859 flush_dcache_mmap_lock(mapping);
860 vma_interval_tree_remove(vma, root);
861 if (adjust_next)
862 vma_interval_tree_remove(next, root);
863 }
864
865 if (start != vma->vm_start) {
866 vma->vm_start = start;
867 start_changed = true;
868 }
869 if (end != vma->vm_end) {
870 vma->vm_end = end;
871 end_changed = true;
872 }
873 vma->vm_pgoff = pgoff;
874 if (adjust_next) {
875 next->vm_start += adjust_next << PAGE_SHIFT;
876 next->vm_pgoff += adjust_next;
877 }
878
879 if (root) {
880 if (adjust_next)
881 vma_interval_tree_insert(next, root);
882 vma_interval_tree_insert(vma, root);
883 flush_dcache_mmap_unlock(mapping);
884 }
885
886 if (remove_next) {
887 /*
888 * vma_merge has merged next into vma, and needs
889 * us to remove next before dropping the locks.
890 */
891 if (remove_next != 3)
892 __vma_unlink_prev(mm, next, vma);
893 else
894 /*
895 * vma is not before next if they've been
896 * swapped.
897 *
898 * pre-swap() next->vm_start was reduced so
899 * tell validate_mm_rb to ignore pre-swap()
900 * "next" (which is stored in post-swap()
901 * "vma").
902 */
903 __vma_unlink_common(mm, next, NULL, false, vma);
904 if (file)
905 __remove_shared_vm_struct(next, file, mapping);
906 } else if (insert) {
907 /*
908 * split_vma has split insert from vma, and needs
909 * us to insert it before dropping the locks
910 * (it may either follow vma or precede it).
911 */
912 __insert_vm_struct(mm, insert);
913 } else {
914 if (start_changed)
915 vma_gap_update(vma);
916 if (end_changed) {
917 if (!next)
918 mm->highest_vm_end = vm_end_gap(vma);
919 else if (!adjust_next)
920 vma_gap_update(next);
921 }
922 }
923
924 if (anon_vma) {
925 anon_vma_interval_tree_post_update_vma(vma);
926 if (adjust_next)
927 anon_vma_interval_tree_post_update_vma(next);
928 anon_vma_unlock_write(anon_vma);
929 }
930 if (mapping)
931 i_mmap_unlock_write(mapping);
932
933 if (root) {
934 uprobe_mmap(vma);
935
936 if (adjust_next)
937 uprobe_mmap(next);
938 }
939
940 if (remove_next) {
941 if (file) {
942 uprobe_munmap(next, next->vm_start, next->vm_end);
943 fput(file);
944 }
945 if (next->anon_vma)
946 anon_vma_merge(vma, next);
947 mm->map_count--;
948 mpol_put(vma_policy(next));
949 vm_area_free(next);
950 /*
951 * In mprotect's case 6 (see comments on vma_merge),
952 * we must remove another next too. It would clutter
953 * up the code too much to do both in one go.
954 */
955 if (remove_next != 3) {
956 /*
957 * If "next" was removed and vma->vm_end was
958 * expanded (up) over it, in turn
959 * "next->vm_prev->vm_end" changed and the
960 * "vma->vm_next" gap must be updated.
961 */
962 next = vma->vm_next;
963 } else {
964 /*
965 * For the scope of the comment "next" and
966 * "vma" considered pre-swap(): if "vma" was
967 * removed, next->vm_start was expanded (down)
968 * over it and the "next" gap must be updated.
969 * Because of the swap() the post-swap() "vma"
970 * actually points to pre-swap() "next"
971 * (post-swap() "next" as opposed is now a
972 * dangling pointer).
973 */
974 next = vma;
975 }
976 if (remove_next == 2) {
977 remove_next = 1;
978 end = next->vm_end;
979 goto again;
980 }
981 else if (next)
982 vma_gap_update(next);
983 else {
984 /*
985 * If remove_next == 2 we obviously can't
986 * reach this path.
987 *
988 * If remove_next == 3 we can't reach this
989 * path because pre-swap() next is always not
990 * NULL. pre-swap() "next" is not being
991 * removed and its next->vm_end is not altered
992 * (and furthermore "end" already matches
993 * next->vm_end in remove_next == 3).
994 *
995 * We reach this only in the remove_next == 1
996 * case if the "next" vma that was removed was
997 * the highest vma of the mm. However in such
998 * case next->vm_end == "end" and the extended
999 * "vma" has vma->vm_end == next->vm_end so
1000 * mm->highest_vm_end doesn't need any update
1001 * in remove_next == 1 case.
1002 */
1003 VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
1004 }
1005 }
1006 if (insert && file)
1007 uprobe_mmap(insert);
1008
1009 validate_mm(mm);
1010
1011 return 0;
1012}
1013
1014/*
1015 * If the vma has a ->close operation then the driver probably needs to release
1016 * per-vma resources, so we don't attempt to merge those.
1017 */
1018static inline int is_mergeable_vma(struct vm_area_struct *vma,
1019 struct file *file, unsigned long vm_flags,
1020 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1021{
1022 /*
1023 * VM_SOFTDIRTY should not prevent from VMA merging, if we
1024 * match the flags but dirty bit -- the caller should mark
1025 * merged VMA as dirty. If dirty bit won't be excluded from
1026 * comparison, we increase pressure on the memory system forcing
1027 * the kernel to generate new VMAs when old one could be
1028 * extended instead.
1029 */
1030 if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
1031 return 0;
1032 if (vma->vm_file != file)
1033 return 0;
1034 if (vma->vm_ops && vma->vm_ops->close)
1035 return 0;
1036 if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
1037 return 0;
1038 return 1;
1039}
1040
1041static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
1042 struct anon_vma *anon_vma2,
1043 struct vm_area_struct *vma)
1044{
1045 /*
1046 * The list_is_singular() test is to avoid merging VMA cloned from
1047 * parents. This can improve scalability caused by anon_vma lock.
1048 */
1049 if ((!anon_vma1 || !anon_vma2) && (!vma ||
1050 list_is_singular(&vma->anon_vma_chain)))
1051 return 1;
1052 return anon_vma1 == anon_vma2;
1053}
1054
1055/*
1056 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
1057 * in front of (at a lower virtual address and file offset than) the vma.
1058 *
1059 * We cannot merge two vmas if they have differently assigned (non-NULL)
1060 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
1061 *
1062 * We don't check here for the merged mmap wrapping around the end of pagecache
1063 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
1064 * wrap, nor mmaps which cover the final page at index -1UL.
1065 */
1066static int
1067can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
1068 struct anon_vma *anon_vma, struct file *file,
1069 pgoff_t vm_pgoff,
1070 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1071{
1072 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
1073 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
1074 if (vma->vm_pgoff == vm_pgoff)
1075 return 1;
1076 }
1077 return 0;
1078}
1079
1080/*
1081 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
1082 * beyond (at a higher virtual address and file offset than) the vma.
1083 *
1084 * We cannot merge two vmas if they have differently assigned (non-NULL)
1085 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
1086 */
1087static int
1088can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
1089 struct anon_vma *anon_vma, struct file *file,
1090 pgoff_t vm_pgoff,
1091 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1092{
1093 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
1094 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
1095 pgoff_t vm_pglen;
1096 vm_pglen = vma_pages(vma);
1097 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
1098 return 1;
1099 }
1100 return 0;
1101}
1102
1103/*
1104 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
1105 * whether that can be merged with its predecessor or its successor.
1106 * Or both (it neatly fills a hole).
1107 *
1108 * In most cases - when called for mmap, brk or mremap - [addr,end) is
1109 * certain not to be mapped by the time vma_merge is called; but when
1110 * called for mprotect, it is certain to be already mapped (either at
1111 * an offset within prev, or at the start of next), and the flags of
1112 * this area are about to be changed to vm_flags - and the no-change
1113 * case has already been eliminated.
1114 *
1115 * The following mprotect cases have to be considered, where AAAA is
1116 * the area passed down from mprotect_fixup, never extending beyond one
1117 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
1118 *
1119 * AAAA AAAA AAAA AAAA
1120 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
1121 * cannot merge might become might become might become
1122 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
1123 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
1124 * mremap move: PPPPXXXXXXXX 8
1125 * AAAA
1126 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
1127 * might become case 1 below case 2 below case 3 below
1128 *
1129 * It is important for case 8 that the vma NNNN overlapping the
1130 * region AAAA is never going to extended over XXXX. Instead XXXX must
1131 * be extended in region AAAA and NNNN must be removed. This way in
1132 * all cases where vma_merge succeeds, the moment vma_adjust drops the
1133 * rmap_locks, the properties of the merged vma will be already
1134 * correct for the whole merged range. Some of those properties like
1135 * vm_page_prot/vm_flags may be accessed by rmap_walks and they must
1136 * be correct for the whole merged range immediately after the
1137 * rmap_locks are released. Otherwise if XXXX would be removed and
1138 * NNNN would be extended over the XXXX range, remove_migration_ptes
1139 * or other rmap walkers (if working on addresses beyond the "end"
1140 * parameter) may establish ptes with the wrong permissions of NNNN
1141 * instead of the right permissions of XXXX.
1142 */
1143struct vm_area_struct *vma_merge(struct mm_struct *mm,
1144 struct vm_area_struct *prev, unsigned long addr,
1145 unsigned long end, unsigned long vm_flags,
1146 struct anon_vma *anon_vma, struct file *file,
1147 pgoff_t pgoff, struct mempolicy *policy,
1148 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1149{
1150 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
1151 struct vm_area_struct *area, *next;
1152 int err;
1153
1154 /*
1155 * We later require that vma->vm_flags == vm_flags,
1156 * so this tests vma->vm_flags & VM_SPECIAL, too.
1157 */
1158 if (vm_flags & VM_SPECIAL)
1159 return NULL;
1160
1161 if (prev)
1162 next = prev->vm_next;
1163 else
1164 next = mm->mmap;
1165 area = next;
1166 if (area && area->vm_end == end) /* cases 6, 7, 8 */
1167 next = next->vm_next;
1168
1169 /* verify some invariant that must be enforced by the caller */
1170 VM_WARN_ON(prev && addr <= prev->vm_start);
1171 VM_WARN_ON(area && end > area->vm_end);
1172 VM_WARN_ON(addr >= end);
1173
1174 /*
1175 * Can it merge with the predecessor?
1176 */
1177 if (prev && prev->vm_end == addr &&
1178 mpol_equal(vma_policy(prev), policy) &&
1179 can_vma_merge_after(prev, vm_flags,
1180 anon_vma, file, pgoff,
1181 vm_userfaultfd_ctx)) {
1182 /*
1183 * OK, it can. Can we now merge in the successor as well?
1184 */
1185 if (next && end == next->vm_start &&
1186 mpol_equal(policy, vma_policy(next)) &&
1187 can_vma_merge_before(next, vm_flags,
1188 anon_vma, file,
1189 pgoff+pglen,
1190 vm_userfaultfd_ctx) &&
1191 is_mergeable_anon_vma(prev->anon_vma,
1192 next->anon_vma, NULL)) {
1193 /* cases 1, 6 */
1194 err = __vma_adjust(prev, prev->vm_start,
1195 next->vm_end, prev->vm_pgoff, NULL,
1196 prev);
1197 } else /* cases 2, 5, 7 */
1198 err = __vma_adjust(prev, prev->vm_start,
1199 end, prev->vm_pgoff, NULL, prev);
1200 if (err)
1201 return NULL;
1202 khugepaged_enter_vma_merge(prev, vm_flags);
1203 return prev;
1204 }
1205
1206 /*
1207 * Can this new request be merged in front of next?
1208 */
1209 if (next && end == next->vm_start &&
1210 mpol_equal(policy, vma_policy(next)) &&
1211 can_vma_merge_before(next, vm_flags,
1212 anon_vma, file, pgoff+pglen,
1213 vm_userfaultfd_ctx)) {
1214 if (prev && addr < prev->vm_end) /* case 4 */
1215 err = __vma_adjust(prev, prev->vm_start,
1216 addr, prev->vm_pgoff, NULL, next);
1217 else { /* cases 3, 8 */
1218 err = __vma_adjust(area, addr, next->vm_end,
1219 next->vm_pgoff - pglen, NULL, next);
1220 /*
1221 * In case 3 area is already equal to next and
1222 * this is a noop, but in case 8 "area" has
1223 * been removed and next was expanded over it.
1224 */
1225 area = next;
1226 }
1227 if (err)
1228 return NULL;
1229 khugepaged_enter_vma_merge(area, vm_flags);
1230 return area;
1231 }
1232
1233 return NULL;
1234}
1235
1236/*
1237 * Rough compatbility check to quickly see if it's even worth looking
1238 * at sharing an anon_vma.
1239 *
1240 * They need to have the same vm_file, and the flags can only differ
1241 * in things that mprotect may change.
1242 *
1243 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1244 * we can merge the two vma's. For example, we refuse to merge a vma if
1245 * there is a vm_ops->close() function, because that indicates that the
1246 * driver is doing some kind of reference counting. But that doesn't
1247 * really matter for the anon_vma sharing case.
1248 */
1249static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1250{
1251 return a->vm_end == b->vm_start &&
1252 mpol_equal(vma_policy(a), vma_policy(b)) &&
1253 a->vm_file == b->vm_file &&
1254 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) &&
1255 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1256}
1257
1258/*
1259 * Do some basic sanity checking to see if we can re-use the anon_vma
1260 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1261 * the same as 'old', the other will be the new one that is trying
1262 * to share the anon_vma.
1263 *
1264 * NOTE! This runs with mm_sem held for reading, so it is possible that
1265 * the anon_vma of 'old' is concurrently in the process of being set up
1266 * by another page fault trying to merge _that_. But that's ok: if it
1267 * is being set up, that automatically means that it will be a singleton
1268 * acceptable for merging, so we can do all of this optimistically. But
1269 * we do that READ_ONCE() to make sure that we never re-load the pointer.
1270 *
1271 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1272 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1273 * is to return an anon_vma that is "complex" due to having gone through
1274 * a fork).
1275 *
1276 * We also make sure that the two vma's are compatible (adjacent,
1277 * and with the same memory policies). That's all stable, even with just
1278 * a read lock on the mm_sem.
1279 */
1280static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1281{
1282 if (anon_vma_compatible(a, b)) {
1283 struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
1284
1285 if (anon_vma && list_is_singular(&old->anon_vma_chain))
1286 return anon_vma;
1287 }
1288 return NULL;
1289}
1290
1291/*
1292 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1293 * neighbouring vmas for a suitable anon_vma, before it goes off
1294 * to allocate a new anon_vma. It checks because a repetitive
1295 * sequence of mprotects and faults may otherwise lead to distinct
1296 * anon_vmas being allocated, preventing vma merge in subsequent
1297 * mprotect.
1298 */
1299struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1300{
1301 struct anon_vma *anon_vma;
1302 struct vm_area_struct *near;
1303
1304 near = vma->vm_next;
1305 if (!near)
1306 goto try_prev;
1307
1308 anon_vma = reusable_anon_vma(near, vma, near);
1309 if (anon_vma)
1310 return anon_vma;
1311try_prev:
1312 near = vma->vm_prev;
1313 if (!near)
1314 goto none;
1315
1316 anon_vma = reusable_anon_vma(near, near, vma);
1317 if (anon_vma)
1318 return anon_vma;
1319none:
1320 /*
1321 * There's no absolute need to look only at touching neighbours:
1322 * we could search further afield for "compatible" anon_vmas.
1323 * But it would probably just be a waste of time searching,
1324 * or lead to too many vmas hanging off the same anon_vma.
1325 * We're trying to allow mprotect remerging later on,
1326 * not trying to minimize memory used for anon_vmas.
1327 */
1328 return NULL;
1329}
1330
1331/*
1332 * If a hint addr is less than mmap_min_addr change hint to be as
1333 * low as possible but still greater than mmap_min_addr
1334 */
1335static inline unsigned long round_hint_to_min(unsigned long hint)
1336{
1337 hint &= PAGE_MASK;
1338 if (((void *)hint != NULL) &&
1339 (hint < mmap_min_addr))
1340 return PAGE_ALIGN(mmap_min_addr);
1341 return hint;
1342}
1343
1344static inline int mlock_future_check(struct mm_struct *mm,
1345 unsigned long flags,
1346 unsigned long len)
1347{
1348 unsigned long locked, lock_limit;
1349
1350 /* mlock MCL_FUTURE? */
1351 if (flags & VM_LOCKED) {
1352 locked = len >> PAGE_SHIFT;
1353 locked += mm->locked_vm;
1354 lock_limit = rlimit(RLIMIT_MEMLOCK);
1355 lock_limit >>= PAGE_SHIFT;
1356 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1357 return -EAGAIN;
1358 }
1359 return 0;
1360}
1361
1362static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
1363{
1364 if (S_ISREG(inode->i_mode))
1365 return MAX_LFS_FILESIZE;
1366
1367 if (S_ISBLK(inode->i_mode))
1368 return MAX_LFS_FILESIZE;
1369
1370 if (S_ISSOCK(inode->i_mode))
1371 return MAX_LFS_FILESIZE;
1372
1373 /* Special "we do even unsigned file positions" case */
1374 if (file->f_mode & FMODE_UNSIGNED_OFFSET)
1375 return 0;
1376
1377 /* Yes, random drivers might want more. But I'm tired of buggy drivers */
1378 return ULONG_MAX;
1379}
1380
1381static inline bool file_mmap_ok(struct file *file, struct inode *inode,
1382 unsigned long pgoff, unsigned long len)
1383{
1384 u64 maxsize = file_mmap_size_max(file, inode);
1385
1386 if (maxsize && len > maxsize)
1387 return false;
1388 maxsize -= len;
1389 if (pgoff > maxsize >> PAGE_SHIFT)
1390 return false;
1391 return true;
1392}
1393
1394/*
1395 * The caller must hold down_write(¤t->mm->mmap_sem).
1396 */
1397unsigned long do_mmap(struct file *file, unsigned long addr,
1398 unsigned long len, unsigned long prot,
1399 unsigned long flags, vm_flags_t vm_flags,
1400 unsigned long pgoff, unsigned long *populate,
1401 struct list_head *uf)
1402{
1403 struct mm_struct *mm = current->mm;
1404 int pkey = 0;
1405
1406 *populate = 0;
1407
1408 if (!len)
1409 return -EINVAL;
1410
1411 /*
1412 * Does the application expect PROT_READ to imply PROT_EXEC?
1413 *
1414 * (the exception is when the underlying filesystem is noexec
1415 * mounted, in which case we dont add PROT_EXEC.)
1416 */
1417 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1418 if (!(file && path_noexec(&file->f_path)))
1419 prot |= PROT_EXEC;
1420
1421 /* force arch specific MAP_FIXED handling in get_unmapped_area */
1422 if (flags & MAP_FIXED_NOREPLACE)
1423 flags |= MAP_FIXED;
1424
1425 if (!(flags & MAP_FIXED))
1426 addr = round_hint_to_min(addr);
1427
1428 /* Careful about overflows.. */
1429 len = PAGE_ALIGN(len);
1430 if (!len)
1431 return -ENOMEM;
1432
1433 /* offset overflow? */
1434 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1435 return -EOVERFLOW;
1436
1437 /* Too many mappings? */
1438 if (mm->map_count > sysctl_max_map_count)
1439 return -ENOMEM;
1440
1441 /* Obtain the address to map to. we verify (or select) it and ensure
1442 * that it represents a valid section of the address space.
1443 */
1444 addr = get_unmapped_area(file, addr, len, pgoff, flags);
1445 if (offset_in_page(addr))
1446 return addr;
1447
1448 if (flags & MAP_FIXED_NOREPLACE) {
1449 struct vm_area_struct *vma = find_vma(mm, addr);
1450
1451 if (vma && vma->vm_start < addr + len)
1452 return -EEXIST;
1453 }
1454
1455 if (prot == PROT_EXEC) {
1456 pkey = execute_only_pkey(mm);
1457 if (pkey < 0)
1458 pkey = 0;
1459 }
1460
1461 /* Do simple checking here so the lower-level routines won't have
1462 * to. we assume access permissions have been handled by the open
1463 * of the memory object, so we don't do any here.
1464 */
1465 vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
1466 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1467
1468 if (flags & MAP_LOCKED)
1469 if (!can_do_mlock())
1470 return -EPERM;
1471
1472 if (mlock_future_check(mm, vm_flags, len))
1473 return -EAGAIN;
1474
1475 if (file) {
1476 struct inode *inode = file_inode(file);
1477 unsigned long flags_mask;
1478
1479 if (!file_mmap_ok(file, inode, pgoff, len))
1480 return -EOVERFLOW;
1481
1482 flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags;
1483
1484 switch (flags & MAP_TYPE) {
1485 case MAP_SHARED:
1486 /*
1487 * Force use of MAP_SHARED_VALIDATE with non-legacy
1488 * flags. E.g. MAP_SYNC is dangerous to use with
1489 * MAP_SHARED as you don't know which consistency model
1490 * you will get. We silently ignore unsupported flags
1491 * with MAP_SHARED to preserve backward compatibility.
1492 */
1493 flags &= LEGACY_MAP_MASK;
1494 /* fall through */
1495 case MAP_SHARED_VALIDATE:
1496 if (flags & ~flags_mask)
1497 return -EOPNOTSUPP;
1498 if (prot & PROT_WRITE) {
1499 if (!(file->f_mode & FMODE_WRITE))
1500 return -EACCES;
1501 if (IS_SWAPFILE(file->f_mapping->host))
1502 return -ETXTBSY;
1503 }
1504
1505 /*
1506 * Make sure we don't allow writing to an append-only
1507 * file..
1508 */
1509 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1510 return -EACCES;
1511
1512 /*
1513 * Make sure there are no mandatory locks on the file.
1514 */
1515 if (locks_verify_locked(file))
1516 return -EAGAIN;
1517
1518 vm_flags |= VM_SHARED | VM_MAYSHARE;
1519 if (!(file->f_mode & FMODE_WRITE))
1520 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1521
1522 /* fall through */
1523 case MAP_PRIVATE:
1524 if (!(file->f_mode & FMODE_READ))
1525 return -EACCES;
1526 if (path_noexec(&file->f_path)) {
1527 if (vm_flags & VM_EXEC)
1528 return -EPERM;
1529 vm_flags &= ~VM_MAYEXEC;
1530 }
1531
1532 if (!file->f_op->mmap)
1533 return -ENODEV;
1534 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1535 return -EINVAL;
1536 break;
1537
1538 default:
1539 return -EINVAL;
1540 }
1541 } else {
1542 switch (flags & MAP_TYPE) {
1543 case MAP_SHARED:
1544 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1545 return -EINVAL;
1546 /*
1547 * Ignore pgoff.
1548 */
1549 pgoff = 0;
1550 vm_flags |= VM_SHARED | VM_MAYSHARE;
1551 break;
1552 case MAP_PRIVATE:
1553 /*
1554 * Set pgoff according to addr for anon_vma.
1555 */
1556 pgoff = addr >> PAGE_SHIFT;
1557 break;
1558 default:
1559 return -EINVAL;
1560 }
1561 }
1562
1563 /*
1564 * Set 'VM_NORESERVE' if we should not account for the
1565 * memory use of this mapping.
1566 */
1567 if (flags & MAP_NORESERVE) {
1568 /* We honor MAP_NORESERVE if allowed to overcommit */
1569 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1570 vm_flags |= VM_NORESERVE;
1571
1572 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1573 if (file && is_file_hugepages(file))
1574 vm_flags |= VM_NORESERVE;
1575 }
1576
1577 addr = mmap_region(file, addr, len, vm_flags, pgoff, uf);
1578 if (!IS_ERR_VALUE(addr) &&
1579 ((vm_flags & VM_LOCKED) ||
1580 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1581 *populate = len;
1582 return addr;
1583}
1584
1585unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
1586 unsigned long prot, unsigned long flags,
1587 unsigned long fd, unsigned long pgoff)
1588{
1589 struct file *file = NULL;
1590 unsigned long retval;
1591
1592 addr = untagged_addr(addr);
1593
1594 if (!(flags & MAP_ANONYMOUS)) {
1595 audit_mmap_fd(fd, flags);
1596 file = fget(fd);
1597 if (!file)
1598 return -EBADF;
1599 if (is_file_hugepages(file))
1600 len = ALIGN(len, huge_page_size(hstate_file(file)));
1601 retval = -EINVAL;
1602 if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
1603 goto out_fput;
1604 } else if (flags & MAP_HUGETLB) {
1605 struct user_struct *user = NULL;
1606 struct hstate *hs;
1607
1608 hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1609 if (!hs)
1610 return -EINVAL;
1611
1612 len = ALIGN(len, huge_page_size(hs));
1613 /*
1614 * VM_NORESERVE is used because the reservations will be
1615 * taken when vm_ops->mmap() is called
1616 * A dummy user value is used because we are not locking
1617 * memory so no accounting is necessary
1618 */
1619 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1620 VM_NORESERVE,
1621 &user, HUGETLB_ANONHUGE_INODE,
1622 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1623 if (IS_ERR(file))
1624 return PTR_ERR(file);
1625 }
1626
1627 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1628
1629 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1630out_fput:
1631 if (file)
1632 fput(file);
1633 return retval;
1634}
1635
1636SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1637 unsigned long, prot, unsigned long, flags,
1638 unsigned long, fd, unsigned long, pgoff)
1639{
1640 return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff);
1641}
1642
1643#ifdef __ARCH_WANT_SYS_OLD_MMAP
1644struct mmap_arg_struct {
1645 unsigned long addr;
1646 unsigned long len;
1647 unsigned long prot;
1648 unsigned long flags;
1649 unsigned long fd;
1650 unsigned long offset;
1651};
1652
1653SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1654{
1655 struct mmap_arg_struct a;
1656
1657 if (copy_from_user(&a, arg, sizeof(a)))
1658 return -EFAULT;
1659 if (offset_in_page(a.offset))
1660 return -EINVAL;
1661
1662 return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1663 a.offset >> PAGE_SHIFT);
1664}
1665#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1666
1667/*
1668 * Some shared mappings will want the pages marked read-only
1669 * to track write events. If so, we'll downgrade vm_page_prot
1670 * to the private version (using protection_map[] without the
1671 * VM_SHARED bit).
1672 */
1673int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot)
1674{
1675 vm_flags_t vm_flags = vma->vm_flags;
1676 const struct vm_operations_struct *vm_ops = vma->vm_ops;
1677
1678 /* If it was private or non-writable, the write bit is already clear */
1679 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1680 return 0;
1681
1682 /* The backer wishes to know when pages are first written to? */
1683 if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite))
1684 return 1;
1685
1686 /* The open routine did something to the protections that pgprot_modify
1687 * won't preserve? */
1688 if (pgprot_val(vm_page_prot) !=
1689 pgprot_val(vm_pgprot_modify(vm_page_prot, vm_flags)))
1690 return 0;
1691
1692 /* Do we need to track softdirty? */
1693 if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY))
1694 return 1;
1695
1696 /* Specialty mapping? */
1697 if (vm_flags & VM_PFNMAP)
1698 return 0;
1699
1700 /* Can the mapping track the dirty pages? */
1701 return vma->vm_file && vma->vm_file->f_mapping &&
1702 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1703}
1704
1705/*
1706 * We account for memory if it's a private writeable mapping,
1707 * not hugepages and VM_NORESERVE wasn't set.
1708 */
1709static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1710{
1711 /*
1712 * hugetlb has its own accounting separate from the core VM
1713 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1714 */
1715 if (file && is_file_hugepages(file))
1716 return 0;
1717
1718 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1719}
1720
1721unsigned long mmap_region(struct file *file, unsigned long addr,
1722 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
1723 struct list_head *uf)
1724{
1725 struct mm_struct *mm = current->mm;
1726 struct vm_area_struct *vma, *prev;
1727 int error;
1728 struct rb_node **rb_link, *rb_parent;
1729 unsigned long charged = 0;
1730
1731 /* Check against address space limit. */
1732 if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
1733 unsigned long nr_pages;
1734
1735 /*
1736 * MAP_FIXED may remove pages of mappings that intersects with
1737 * requested mapping. Account for the pages it would unmap.
1738 */
1739 nr_pages = count_vma_pages_range(mm, addr, addr + len);
1740
1741 if (!may_expand_vm(mm, vm_flags,
1742 (len >> PAGE_SHIFT) - nr_pages))
1743 return -ENOMEM;
1744 }
1745
1746 /* Clear old maps */
1747 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
1748 &rb_parent)) {
1749 if (do_munmap(mm, addr, len, uf))
1750 return -ENOMEM;
1751 }
1752
1753 /*
1754 * Private writable mapping: check memory availability
1755 */
1756 if (accountable_mapping(file, vm_flags)) {
1757 charged = len >> PAGE_SHIFT;
1758 if (security_vm_enough_memory_mm(mm, charged))
1759 return -ENOMEM;
1760 vm_flags |= VM_ACCOUNT;
1761 }
1762
1763 /*
1764 * Can we just expand an old mapping?
1765 */
1766 vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
1767 NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX);
1768 if (vma)
1769 goto out;
1770
1771 /*
1772 * Determine the object being mapped and call the appropriate
1773 * specific mapper. the address has already been validated, but
1774 * not unmapped, but the maps are removed from the list.
1775 */
1776 vma = vm_area_alloc(mm);
1777 if (!vma) {
1778 error = -ENOMEM;
1779 goto unacct_error;
1780 }
1781
1782 vma->vm_start = addr;
1783 vma->vm_end = addr + len;
1784 vma->vm_flags = vm_flags;
1785 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1786 vma->vm_pgoff = pgoff;
1787
1788 if (file) {
1789 if (vm_flags & VM_DENYWRITE) {
1790 error = deny_write_access(file);
1791 if (error)
1792 goto free_vma;
1793 }
1794 if (vm_flags & VM_SHARED) {
1795 error = mapping_map_writable(file->f_mapping);
1796 if (error)
1797 goto allow_write_and_free_vma;
1798 }
1799
1800 /* ->mmap() can change vma->vm_file, but must guarantee that
1801 * vma_link() below can deny write-access if VM_DENYWRITE is set
1802 * and map writably if VM_SHARED is set. This usually means the
1803 * new file must not have been exposed to user-space, yet.
1804 */
1805 vma->vm_file = get_file(file);
1806 error = call_mmap(file, vma);
1807 if (error)
1808 goto unmap_and_free_vma;
1809
1810 /* Can addr have changed??
1811 *
1812 * Answer: Yes, several device drivers can do it in their
1813 * f_op->mmap method. -DaveM
1814 * Bug: If addr is changed, prev, rb_link, rb_parent should
1815 * be updated for vma_link()
1816 */
1817 WARN_ON_ONCE(addr != vma->vm_start);
1818
1819 addr = vma->vm_start;
1820 vm_flags = vma->vm_flags;
1821 } else if (vm_flags & VM_SHARED) {
1822 error = shmem_zero_setup(vma);
1823 if (error)
1824 goto free_vma;
1825 } else {
1826 vma_set_anonymous(vma);
1827 }
1828
1829 vma_link(mm, vma, prev, rb_link, rb_parent);
1830 /* Once vma denies write, undo our temporary denial count */
1831 if (file) {
1832 if (vm_flags & VM_SHARED)
1833 mapping_unmap_writable(file->f_mapping);
1834 if (vm_flags & VM_DENYWRITE)
1835 allow_write_access(file);
1836 }
1837 file = vma->vm_file;
1838out:
1839 perf_event_mmap(vma);
1840
1841 vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
1842 if (vm_flags & VM_LOCKED) {
1843 if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) ||
1844 is_vm_hugetlb_page(vma) ||
1845 vma == get_gate_vma(current->mm))
1846 vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
1847 else
1848 mm->locked_vm += (len >> PAGE_SHIFT);
1849 }
1850
1851 if (file)
1852 uprobe_mmap(vma);
1853
1854 /*
1855 * New (or expanded) vma always get soft dirty status.
1856 * Otherwise user-space soft-dirty page tracker won't
1857 * be able to distinguish situation when vma area unmapped,
1858 * then new mapped in-place (which must be aimed as
1859 * a completely new data area).
1860 */
1861 vma->vm_flags |= VM_SOFTDIRTY;
1862
1863 vma_set_page_prot(vma);
1864
1865 return addr;
1866
1867unmap_and_free_vma:
1868 vma->vm_file = NULL;
1869 fput(file);
1870
1871 /* Undo any partial mapping done by a device driver. */
1872 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1873 charged = 0;
1874 if (vm_flags & VM_SHARED)
1875 mapping_unmap_writable(file->f_mapping);
1876allow_write_and_free_vma:
1877 if (vm_flags & VM_DENYWRITE)
1878 allow_write_access(file);
1879free_vma:
1880 vm_area_free(vma);
1881unacct_error:
1882 if (charged)
1883 vm_unacct_memory(charged);
1884 return error;
1885}
1886
1887unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1888{
1889 /*
1890 * We implement the search by looking for an rbtree node that
1891 * immediately follows a suitable gap. That is,
1892 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1893 * - gap_end = vma->vm_start >= info->low_limit + length;
1894 * - gap_end - gap_start >= length
1895 */
1896
1897 struct mm_struct *mm = current->mm;
1898 struct vm_area_struct *vma;
1899 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1900
1901 /* Adjust search length to account for worst case alignment overhead */
1902 length = info->length + info->align_mask;
1903 if (length < info->length)
1904 return -ENOMEM;
1905
1906 /* Adjust search limits by the desired length */
1907 if (info->high_limit < length)
1908 return -ENOMEM;
1909 high_limit = info->high_limit - length;
1910
1911 if (info->low_limit > high_limit)
1912 return -ENOMEM;
1913 low_limit = info->low_limit + length;
1914
1915 /* Check if rbtree root looks promising */
1916 if (RB_EMPTY_ROOT(&mm->mm_rb))
1917 goto check_highest;
1918 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1919 if (vma->rb_subtree_gap < length)
1920 goto check_highest;
1921
1922 while (true) {
1923 /* Visit left subtree if it looks promising */
1924 gap_end = vm_start_gap(vma);
1925 if (gap_end >= low_limit && vma->vm_rb.rb_left) {
1926 struct vm_area_struct *left =
1927 rb_entry(vma->vm_rb.rb_left,
1928 struct vm_area_struct, vm_rb);
1929 if (left->rb_subtree_gap >= length) {
1930 vma = left;
1931 continue;
1932 }
1933 }
1934
1935 gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
1936check_current:
1937 /* Check if current node has a suitable gap */
1938 if (gap_start > high_limit)
1939 return -ENOMEM;
1940 if (gap_end >= low_limit &&
1941 gap_end > gap_start && gap_end - gap_start >= length)
1942 goto found;
1943
1944 /* Visit right subtree if it looks promising */
1945 if (vma->vm_rb.rb_right) {
1946 struct vm_area_struct *right =
1947 rb_entry(vma->vm_rb.rb_right,
1948 struct vm_area_struct, vm_rb);
1949 if (right->rb_subtree_gap >= length) {
1950 vma = right;
1951 continue;
1952 }
1953 }
1954
1955 /* Go back up the rbtree to find next candidate node */
1956 while (true) {
1957 struct rb_node *prev = &vma->vm_rb;
1958 if (!rb_parent(prev))
1959 goto check_highest;
1960 vma = rb_entry(rb_parent(prev),
1961 struct vm_area_struct, vm_rb);
1962 if (prev == vma->vm_rb.rb_left) {
1963 gap_start = vm_end_gap(vma->vm_prev);
1964 gap_end = vm_start_gap(vma);
1965 goto check_current;
1966 }
1967 }
1968 }
1969
1970check_highest:
1971 /* Check highest gap, which does not precede any rbtree node */
1972 gap_start = mm->highest_vm_end;
1973 gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */
1974 if (gap_start > high_limit)
1975 return -ENOMEM;
1976
1977found:
1978 /* We found a suitable gap. Clip it with the original low_limit. */
1979 if (gap_start < info->low_limit)
1980 gap_start = info->low_limit;
1981
1982 /* Adjust gap address to the desired alignment */
1983 gap_start += (info->align_offset - gap_start) & info->align_mask;
1984
1985 VM_BUG_ON(gap_start + info->length > info->high_limit);
1986 VM_BUG_ON(gap_start + info->length > gap_end);
1987 return gap_start;
1988}
1989
1990unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
1991{
1992 struct mm_struct *mm = current->mm;
1993 struct vm_area_struct *vma;
1994 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1995
1996 /* Adjust search length to account for worst case alignment overhead */
1997 length = info->length + info->align_mask;
1998 if (length < info->length)
1999 return -ENOMEM;
2000
2001 /*
2002 * Adjust search limits by the desired length.
2003 * See implementation comment at top of unmapped_area().
2004 */
2005 gap_end = info->high_limit;
2006 if (gap_end < length)
2007 return -ENOMEM;
2008 high_limit = gap_end - length;
2009
2010 if (info->low_limit > high_limit)
2011 return -ENOMEM;
2012 low_limit = info->low_limit + length;
2013
2014 /* Check highest gap, which does not precede any rbtree node */
2015 gap_start = mm->highest_vm_end;
2016 if (gap_start <= high_limit)
2017 goto found_highest;
2018
2019 /* Check if rbtree root looks promising */
2020 if (RB_EMPTY_ROOT(&mm->mm_rb))
2021 return -ENOMEM;
2022 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
2023 if (vma->rb_subtree_gap < length)
2024 return -ENOMEM;
2025
2026 while (true) {
2027 /* Visit right subtree if it looks promising */
2028 gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
2029 if (gap_start <= high_limit && vma->vm_rb.rb_right) {
2030 struct vm_area_struct *right =
2031 rb_entry(vma->vm_rb.rb_right,
2032 struct vm_area_struct, vm_rb);
2033 if (right->rb_subtree_gap >= length) {
2034 vma = right;
2035 continue;
2036 }
2037 }
2038
2039check_current:
2040 /* Check if current node has a suitable gap */
2041 gap_end = vm_start_gap(vma);
2042 if (gap_end < low_limit)
2043 return -ENOMEM;
2044 if (gap_start <= high_limit &&
2045 gap_end > gap_start && gap_end - gap_start >= length)
2046 goto found;
2047
2048 /* Visit left subtree if it looks promising */
2049 if (vma->vm_rb.rb_left) {
2050 struct vm_area_struct *left =
2051 rb_entry(vma->vm_rb.rb_left,
2052 struct vm_area_struct, vm_rb);
2053 if (left->rb_subtree_gap >= length) {
2054 vma = left;
2055 continue;
2056 }
2057 }
2058
2059 /* Go back up the rbtree to find next candidate node */
2060 while (true) {
2061 struct rb_node *prev = &vma->vm_rb;
2062 if (!rb_parent(prev))
2063 return -ENOMEM;
2064 vma = rb_entry(rb_parent(prev),
2065 struct vm_area_struct, vm_rb);
2066 if (prev == vma->vm_rb.rb_right) {
2067 gap_start = vma->vm_prev ?
2068 vm_end_gap(vma->vm_prev) : 0;
2069 goto check_current;
2070 }
2071 }
2072 }
2073
2074found:
2075 /* We found a suitable gap. Clip it with the original high_limit. */
2076 if (gap_end > info->high_limit)
2077 gap_end = info->high_limit;
2078
2079found_highest:
2080 /* Compute highest gap address at the desired alignment */
2081 gap_end -= info->length;
2082 gap_end -= (gap_end - info->align_offset) & info->align_mask;
2083
2084 VM_BUG_ON(gap_end < info->low_limit);
2085 VM_BUG_ON(gap_end < gap_start);
2086 return gap_end;
2087}
2088
2089
2090#ifndef arch_get_mmap_end
2091#define arch_get_mmap_end(addr) (TASK_SIZE)
2092#endif
2093
2094#ifndef arch_get_mmap_base
2095#define arch_get_mmap_base(addr, base) (base)
2096#endif
2097
2098/* Get an address range which is currently unmapped.
2099 * For shmat() with addr=0.
2100 *
2101 * Ugly calling convention alert:
2102 * Return value with the low bits set means error value,
2103 * ie
2104 * if (ret & ~PAGE_MASK)
2105 * error = ret;
2106 *
2107 * This function "knows" that -ENOMEM has the bits set.
2108 */
2109#ifndef HAVE_ARCH_UNMAPPED_AREA
2110unsigned long
2111arch_get_unmapped_area(struct file *filp, unsigned long addr,
2112 unsigned long len, unsigned long pgoff, unsigned long flags)
2113{
2114 struct mm_struct *mm = current->mm;
2115 struct vm_area_struct *vma, *prev;
2116 struct vm_unmapped_area_info info;
2117 const unsigned long mmap_end = arch_get_mmap_end(addr);
2118
2119 if (len > mmap_end - mmap_min_addr)
2120 return -ENOMEM;
2121
2122 if (flags & MAP_FIXED)
2123 return addr;
2124
2125 if (addr) {
2126 addr = PAGE_ALIGN(addr);
2127 vma = find_vma_prev(mm, addr, &prev);
2128 if (mmap_end - len >= addr && addr >= mmap_min_addr &&
2129 (!vma || addr + len <= vm_start_gap(vma)) &&
2130 (!prev || addr >= vm_end_gap(prev)))
2131 return addr;
2132 }
2133
2134 info.flags = 0;
2135 info.length = len;
2136 info.low_limit = mm->mmap_base;
2137 info.high_limit = mmap_end;
2138 info.align_mask = 0;
2139 return vm_unmapped_area(&info);
2140}
2141#endif
2142
2143/*
2144 * This mmap-allocator allocates new areas top-down from below the
2145 * stack's low limit (the base):
2146 */
2147#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
2148unsigned long
2149arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
2150 unsigned long len, unsigned long pgoff,
2151 unsigned long flags)
2152{
2153 struct vm_area_struct *vma, *prev;
2154 struct mm_struct *mm = current->mm;
2155 struct vm_unmapped_area_info info;
2156 const unsigned long mmap_end = arch_get_mmap_end(addr);
2157
2158 /* requested length too big for entire address space */
2159 if (len > mmap_end - mmap_min_addr)
2160 return -ENOMEM;
2161
2162 if (flags & MAP_FIXED)
2163 return addr;
2164
2165 /* requesting a specific address */
2166 if (addr) {
2167 addr = PAGE_ALIGN(addr);
2168 vma = find_vma_prev(mm, addr, &prev);
2169 if (mmap_end - len >= addr && addr >= mmap_min_addr &&
2170 (!vma || addr + len <= vm_start_gap(vma)) &&
2171 (!prev || addr >= vm_end_gap(prev)))
2172 return addr;
2173 }
2174
2175 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
2176 info.length = len;
2177 info.low_limit = max(PAGE_SIZE, mmap_min_addr);
2178 info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
2179 info.align_mask = 0;
2180 addr = vm_unmapped_area(&info);
2181
2182 /*
2183 * A failed mmap() very likely causes application failure,
2184 * so fall back to the bottom-up function here. This scenario
2185 * can happen with large stack limits and large mmap()
2186 * allocations.
2187 */
2188 if (offset_in_page(addr)) {
2189 VM_BUG_ON(addr != -ENOMEM);
2190 info.flags = 0;
2191 info.low_limit = TASK_UNMAPPED_BASE;
2192 info.high_limit = mmap_end;
2193 addr = vm_unmapped_area(&info);
2194 }
2195
2196 return addr;
2197}
2198#endif
2199
2200unsigned long
2201get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
2202 unsigned long pgoff, unsigned long flags)
2203{
2204 unsigned long (*get_area)(struct file *, unsigned long,
2205 unsigned long, unsigned long, unsigned long);
2206
2207 unsigned long error = arch_mmap_check(addr, len, flags);
2208 if (error)
2209 return error;
2210
2211 /* Careful about overflows.. */
2212 if (len > TASK_SIZE)
2213 return -ENOMEM;
2214
2215 get_area = current->mm->get_unmapped_area;
2216 if (file) {
2217 if (file->f_op->get_unmapped_area)
2218 get_area = file->f_op->get_unmapped_area;
2219 } else if (flags & MAP_SHARED) {
2220 /*
2221 * mmap_region() will call shmem_zero_setup() to create a file,
2222 * so use shmem's get_unmapped_area in case it can be huge.
2223 * do_mmap_pgoff() will clear pgoff, so match alignment.
2224 */
2225 pgoff = 0;
2226 get_area = shmem_get_unmapped_area;
2227 }
2228
2229 addr = get_area(file, addr, len, pgoff, flags);
2230 if (IS_ERR_VALUE(addr))
2231 return addr;
2232
2233 if (addr > TASK_SIZE - len)
2234 return -ENOMEM;
2235 if (offset_in_page(addr))
2236 return -EINVAL;
2237
2238 error = security_mmap_addr(addr);
2239 return error ? error : addr;
2240}
2241
2242EXPORT_SYMBOL(get_unmapped_area);
2243
2244/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
2245struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
2246{
2247 struct rb_node *rb_node;
2248 struct vm_area_struct *vma;
2249
2250 /* Check the cache first. */
2251 vma = vmacache_find(mm, addr);
2252 if (likely(vma))
2253 return vma;
2254
2255 rb_node = mm->mm_rb.rb_node;
2256
2257 while (rb_node) {
2258 struct vm_area_struct *tmp;
2259
2260 tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2261
2262 if (tmp->vm_end > addr) {
2263 vma = tmp;
2264 if (tmp->vm_start <= addr)
2265 break;
2266 rb_node = rb_node->rb_left;
2267 } else
2268 rb_node = rb_node->rb_right;
2269 }
2270
2271 if (vma)
2272 vmacache_update(addr, vma);
2273 return vma;
2274}
2275
2276EXPORT_SYMBOL(find_vma);
2277
2278/*
2279 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
2280 */
2281struct vm_area_struct *
2282find_vma_prev(struct mm_struct *mm, unsigned long addr,
2283 struct vm_area_struct **pprev)
2284{
2285 struct vm_area_struct *vma;
2286
2287 vma = find_vma(mm, addr);
2288 if (vma) {
2289 *pprev = vma->vm_prev;
2290 } else {
2291 struct rb_node *rb_node = rb_last(&mm->mm_rb);
2292
2293 *pprev = rb_node ? rb_entry(rb_node, struct vm_area_struct, vm_rb) : NULL;
2294 }
2295 return vma;
2296}
2297
2298/*
2299 * Verify that the stack growth is acceptable and
2300 * update accounting. This is shared with both the
2301 * grow-up and grow-down cases.
2302 */
2303static int acct_stack_growth(struct vm_area_struct *vma,
2304 unsigned long size, unsigned long grow)
2305{
2306 struct mm_struct *mm = vma->vm_mm;
2307 unsigned long new_start;
2308
2309 /* address space limit tests */
2310 if (!may_expand_vm(mm, vma->vm_flags, grow))
2311 return -ENOMEM;
2312
2313 /* Stack limit test */
2314 if (size > rlimit(RLIMIT_STACK))
2315 return -ENOMEM;
2316
2317 /* mlock limit tests */
2318 if (vma->vm_flags & VM_LOCKED) {
2319 unsigned long locked;
2320 unsigned long limit;
2321 locked = mm->locked_vm + grow;
2322 limit = rlimit(RLIMIT_MEMLOCK);
2323 limit >>= PAGE_SHIFT;
2324 if (locked > limit && !capable(CAP_IPC_LOCK))
2325 return -ENOMEM;
2326 }
2327
2328 /* Check to ensure the stack will not grow into a hugetlb-only region */
2329 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
2330 vma->vm_end - size;
2331 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
2332 return -EFAULT;
2333
2334 /*
2335 * Overcommit.. This must be the final test, as it will
2336 * update security statistics.
2337 */
2338 if (security_vm_enough_memory_mm(mm, grow))
2339 return -ENOMEM;
2340
2341 return 0;
2342}
2343
2344#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2345/*
2346 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2347 * vma is the last one with address > vma->vm_end. Have to extend vma.
2348 */
2349int expand_upwards(struct vm_area_struct *vma, unsigned long address)
2350{
2351 struct mm_struct *mm = vma->vm_mm;
2352 struct vm_area_struct *next;
2353 unsigned long gap_addr;
2354 int error = 0;
2355
2356 if (!(vma->vm_flags & VM_GROWSUP))
2357 return -EFAULT;
2358
2359 /* Guard against exceeding limits of the address space. */
2360 address &= PAGE_MASK;
2361 if (address >= (TASK_SIZE & PAGE_MASK))
2362 return -ENOMEM;
2363 address += PAGE_SIZE;
2364
2365 /* Enforce stack_guard_gap */
2366 gap_addr = address + stack_guard_gap;
2367
2368 /* Guard against overflow */
2369 if (gap_addr < address || gap_addr > TASK_SIZE)
2370 gap_addr = TASK_SIZE;
2371
2372 next = vma->vm_next;
2373 if (next && next->vm_start < gap_addr &&
2374 (next->vm_flags & (VM_WRITE|VM_READ|VM_EXEC))) {
2375 if (!(next->vm_flags & VM_GROWSUP))
2376 return -ENOMEM;
2377 /* Check that both stack segments have the same anon_vma? */
2378 }
2379
2380 /* We must make sure the anon_vma is allocated. */
2381 if (unlikely(anon_vma_prepare(vma)))
2382 return -ENOMEM;
2383
2384 /*
2385 * vma->vm_start/vm_end cannot change under us because the caller
2386 * is required to hold the mmap_sem in read mode. We need the
2387 * anon_vma lock to serialize against concurrent expand_stacks.
2388 */
2389 anon_vma_lock_write(vma->anon_vma);
2390
2391 /* Somebody else might have raced and expanded it already */
2392 if (address > vma->vm_end) {
2393 unsigned long size, grow;
2394
2395 size = address - vma->vm_start;
2396 grow = (address - vma->vm_end) >> PAGE_SHIFT;
2397
2398 error = -ENOMEM;
2399 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2400 error = acct_stack_growth(vma, size, grow);
2401 if (!error) {
2402 /*
2403 * vma_gap_update() doesn't support concurrent
2404 * updates, but we only hold a shared mmap_sem
2405 * lock here, so we need to protect against
2406 * concurrent vma expansions.
2407 * anon_vma_lock_write() doesn't help here, as
2408 * we don't guarantee that all growable vmas
2409 * in a mm share the same root anon vma.
2410 * So, we reuse mm->page_table_lock to guard
2411 * against concurrent vma expansions.
2412 */
2413 spin_lock(&mm->page_table_lock);
2414 if (vma->vm_flags & VM_LOCKED)
2415 mm->locked_vm += grow;
2416 vm_stat_account(mm, vma->vm_flags, grow);
2417 anon_vma_interval_tree_pre_update_vma(vma);
2418 vma->vm_end = address;
2419 anon_vma_interval_tree_post_update_vma(vma);
2420 if (vma->vm_next)
2421 vma_gap_update(vma->vm_next);
2422 else
2423 mm->highest_vm_end = vm_end_gap(vma);
2424 spin_unlock(&mm->page_table_lock);
2425
2426 perf_event_mmap(vma);
2427 }
2428 }
2429 }
2430 anon_vma_unlock_write(vma->anon_vma);
2431 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2432 validate_mm(mm);
2433 return error;
2434}
2435#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2436
2437/*
2438 * vma is the first one with address < vma->vm_start. Have to extend vma.
2439 */
2440int expand_downwards(struct vm_area_struct *vma,
2441 unsigned long address)
2442{
2443 struct mm_struct *mm = vma->vm_mm;
2444 struct vm_area_struct *prev;
2445 int error = 0;
2446
2447 address &= PAGE_MASK;
2448 if (address < mmap_min_addr)
2449 return -EPERM;
2450
2451 /* Enforce stack_guard_gap */
2452 prev = vma->vm_prev;
2453 /* Check that both stack segments have the same anon_vma? */
2454 if (prev && !(prev->vm_flags & VM_GROWSDOWN) &&
2455 (prev->vm_flags & (VM_WRITE|VM_READ|VM_EXEC))) {
2456 if (address - prev->vm_end < stack_guard_gap)
2457 return -ENOMEM;
2458 }
2459
2460 /* We must make sure the anon_vma is allocated. */
2461 if (unlikely(anon_vma_prepare(vma)))
2462 return -ENOMEM;
2463
2464 /*
2465 * vma->vm_start/vm_end cannot change under us because the caller
2466 * is required to hold the mmap_sem in read mode. We need the
2467 * anon_vma lock to serialize against concurrent expand_stacks.
2468 */
2469 anon_vma_lock_write(vma->anon_vma);
2470
2471 /* Somebody else might have raced and expanded it already */
2472 if (address < vma->vm_start) {
2473 unsigned long size, grow;
2474
2475 size = vma->vm_end - address;
2476 grow = (vma->vm_start - address) >> PAGE_SHIFT;
2477
2478 error = -ENOMEM;
2479 if (grow <= vma->vm_pgoff) {
2480 error = acct_stack_growth(vma, size, grow);
2481 if (!error) {
2482 /*
2483 * vma_gap_update() doesn't support concurrent
2484 * updates, but we only hold a shared mmap_sem
2485 * lock here, so we need to protect against
2486 * concurrent vma expansions.
2487 * anon_vma_lock_write() doesn't help here, as
2488 * we don't guarantee that all growable vmas
2489 * in a mm share the same root anon vma.
2490 * So, we reuse mm->page_table_lock to guard
2491 * against concurrent vma expansions.
2492 */
2493 spin_lock(&mm->page_table_lock);
2494 if (vma->vm_flags & VM_LOCKED)
2495 mm->locked_vm += grow;
2496 vm_stat_account(mm, vma->vm_flags, grow);
2497 anon_vma_interval_tree_pre_update_vma(vma);
2498 vma->vm_start = address;
2499 vma->vm_pgoff -= grow;
2500 anon_vma_interval_tree_post_update_vma(vma);
2501 vma_gap_update(vma);
2502 spin_unlock(&mm->page_table_lock);
2503
2504 perf_event_mmap(vma);
2505 }
2506 }
2507 }
2508 anon_vma_unlock_write(vma->anon_vma);
2509 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2510 validate_mm(mm);
2511 return error;
2512}
2513
2514/* enforced gap between the expanding stack and other mappings. */
2515unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
2516
2517static int __init cmdline_parse_stack_guard_gap(char *p)
2518{
2519 unsigned long val;
2520 char *endptr;
2521
2522 val = simple_strtoul(p, &endptr, 10);
2523 if (!*endptr)
2524 stack_guard_gap = val << PAGE_SHIFT;
2525
2526 return 0;
2527}
2528__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
2529
2530#ifdef CONFIG_STACK_GROWSUP
2531int expand_stack(struct vm_area_struct *vma, unsigned long address)
2532{
2533 return expand_upwards(vma, address);
2534}
2535
2536struct vm_area_struct *
2537find_extend_vma(struct mm_struct *mm, unsigned long addr)
2538{
2539 struct vm_area_struct *vma, *prev;
2540
2541 addr &= PAGE_MASK;
2542 vma = find_vma_prev(mm, addr, &prev);
2543 if (vma && (vma->vm_start <= addr))
2544 return vma;
2545 /* don't alter vm_end if the coredump is running */
2546 if (!prev || !mmget_still_valid(mm) || expand_stack(prev, addr))
2547 return NULL;
2548 if (prev->vm_flags & VM_LOCKED)
2549 populate_vma_page_range(prev, addr, prev->vm_end, NULL);
2550 return prev;
2551}
2552#else
2553int expand_stack(struct vm_area_struct *vma, unsigned long address)
2554{
2555 return expand_downwards(vma, address);
2556}
2557
2558struct vm_area_struct *
2559find_extend_vma(struct mm_struct *mm, unsigned long addr)
2560{
2561 struct vm_area_struct *vma;
2562 unsigned long start;
2563
2564 addr &= PAGE_MASK;
2565 vma = find_vma(mm, addr);
2566 if (!vma)
2567 return NULL;
2568 if (vma->vm_start <= addr)
2569 return vma;
2570 if (!(vma->vm_flags & VM_GROWSDOWN))
2571 return NULL;
2572 /* don't alter vm_start if the coredump is running */
2573 if (!mmget_still_valid(mm))
2574 return NULL;
2575 start = vma->vm_start;
2576 if (expand_stack(vma, addr))
2577 return NULL;
2578 if (vma->vm_flags & VM_LOCKED)
2579 populate_vma_page_range(vma, addr, start, NULL);
2580 return vma;
2581}
2582#endif
2583
2584EXPORT_SYMBOL_GPL(find_extend_vma);
2585
2586/*
2587 * Ok - we have the memory areas we should free on the vma list,
2588 * so release them, and do the vma updates.
2589 *
2590 * Called with the mm semaphore held.
2591 */
2592static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
2593{
2594 unsigned long nr_accounted = 0;
2595
2596 /* Update high watermark before we lower total_vm */
2597 update_hiwater_vm(mm);
2598 do {
2599 long nrpages = vma_pages(vma);
2600
2601 if (vma->vm_flags & VM_ACCOUNT)
2602 nr_accounted += nrpages;
2603 vm_stat_account(mm, vma->vm_flags, -nrpages);
2604 vma = remove_vma(vma);
2605 } while (vma);
2606 vm_unacct_memory(nr_accounted);
2607 validate_mm(mm);
2608}
2609
2610/*
2611 * Get rid of page table information in the indicated region.
2612 *
2613 * Called with the mm semaphore held.
2614 */
2615static void unmap_region(struct mm_struct *mm,
2616 struct vm_area_struct *vma, struct vm_area_struct *prev,
2617 unsigned long start, unsigned long end)
2618{
2619 struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap;
2620 struct mmu_gather tlb;
2621
2622 lru_add_drain();
2623 tlb_gather_mmu(&tlb, mm, start, end);
2624 update_hiwater_rss(mm);
2625 unmap_vmas(&tlb, vma, start, end);
2626 free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2627 next ? next->vm_start : USER_PGTABLES_CEILING);
2628 tlb_finish_mmu(&tlb, start, end);
2629}
2630
2631/*
2632 * Create a list of vma's touched by the unmap, removing them from the mm's
2633 * vma list as we go..
2634 */
2635static void
2636detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
2637 struct vm_area_struct *prev, unsigned long end)
2638{
2639 struct vm_area_struct **insertion_point;
2640 struct vm_area_struct *tail_vma = NULL;
2641
2642 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2643 vma->vm_prev = NULL;
2644 do {
2645 vma_rb_erase(vma, &mm->mm_rb);
2646 mm->map_count--;
2647 tail_vma = vma;
2648 vma = vma->vm_next;
2649 } while (vma && vma->vm_start < end);
2650 *insertion_point = vma;
2651 if (vma) {
2652 vma->vm_prev = prev;
2653 vma_gap_update(vma);
2654 } else
2655 mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
2656 tail_vma->vm_next = NULL;
2657
2658 /* Kill the cache */
2659 vmacache_invalidate(mm);
2660}
2661
2662/*
2663 * __split_vma() bypasses sysctl_max_map_count checking. We use this where it
2664 * has already been checked or doesn't make sense to fail.
2665 */
2666int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2667 unsigned long addr, int new_below)
2668{
2669 struct vm_area_struct *new;
2670 int err;
2671
2672 if (vma->vm_ops && vma->vm_ops->split) {
2673 err = vma->vm_ops->split(vma, addr);
2674 if (err)
2675 return err;
2676 }
2677
2678 new = vm_area_dup(vma);
2679 if (!new)
2680 return -ENOMEM;
2681
2682 if (new_below)
2683 new->vm_end = addr;
2684 else {
2685 new->vm_start = addr;
2686 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2687 }
2688
2689 err = vma_dup_policy(vma, new);
2690 if (err)
2691 goto out_free_vma;
2692
2693 err = anon_vma_clone(new, vma);
2694 if (err)
2695 goto out_free_mpol;
2696
2697 if (new->vm_file)
2698 get_file(new->vm_file);
2699
2700 if (new->vm_ops && new->vm_ops->open)
2701 new->vm_ops->open(new);
2702
2703 if (new_below)
2704 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2705 ((addr - new->vm_start) >> PAGE_SHIFT), new);
2706 else
2707 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2708
2709 /* Success. */
2710 if (!err)
2711 return 0;
2712
2713 /* Clean everything up if vma_adjust failed. */
2714 if (new->vm_ops && new->vm_ops->close)
2715 new->vm_ops->close(new);
2716 if (new->vm_file)
2717 fput(new->vm_file);
2718 unlink_anon_vmas(new);
2719 out_free_mpol:
2720 mpol_put(vma_policy(new));
2721 out_free_vma:
2722 vm_area_free(new);
2723 return err;
2724}
2725
2726/*
2727 * Split a vma into two pieces at address 'addr', a new vma is allocated
2728 * either for the first part or the tail.
2729 */
2730int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2731 unsigned long addr, int new_below)
2732{
2733 if (mm->map_count >= sysctl_max_map_count)
2734 return -ENOMEM;
2735
2736 return __split_vma(mm, vma, addr, new_below);
2737}
2738
2739/* Munmap is split into 2 main parts -- this part which finds
2740 * what needs doing, and the areas themselves, which do the
2741 * work. This now handles partial unmappings.
2742 * Jeremy Fitzhardinge <jeremy@goop.org>
2743 */
2744int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
2745 struct list_head *uf, bool downgrade)
2746{
2747 unsigned long end;
2748 struct vm_area_struct *vma, *prev, *last;
2749
2750 if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
2751 return -EINVAL;
2752
2753 len = PAGE_ALIGN(len);
2754 end = start + len;
2755 if (len == 0)
2756 return -EINVAL;
2757
2758 /*
2759 * arch_unmap() might do unmaps itself. It must be called
2760 * and finish any rbtree manipulation before this code
2761 * runs and also starts to manipulate the rbtree.
2762 */
2763 arch_unmap(mm, start, end);
2764
2765 /* Find the first overlapping VMA */
2766 vma = find_vma(mm, start);
2767 if (!vma)
2768 return 0;
2769 prev = vma->vm_prev;
2770 /* we have start < vma->vm_end */
2771
2772 /* if it doesn't overlap, we have nothing.. */
2773 if (vma->vm_start >= end)
2774 return 0;
2775
2776 /*
2777 * If we need to split any vma, do it now to save pain later.
2778 *
2779 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2780 * unmapped vm_area_struct will remain in use: so lower split_vma
2781 * places tmp vma above, and higher split_vma places tmp vma below.
2782 */
2783 if (start > vma->vm_start) {
2784 int error;
2785
2786 /*
2787 * Make sure that map_count on return from munmap() will
2788 * not exceed its limit; but let map_count go just above
2789 * its limit temporarily, to help free resources as expected.
2790 */
2791 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2792 return -ENOMEM;
2793
2794 error = __split_vma(mm, vma, start, 0);
2795 if (error)
2796 return error;
2797 prev = vma;
2798 }
2799
2800 /* Does it split the last one? */
2801 last = find_vma(mm, end);
2802 if (last && end > last->vm_start) {
2803 int error = __split_vma(mm, last, end, 1);
2804 if (error)
2805 return error;
2806 }
2807 vma = prev ? prev->vm_next : mm->mmap;
2808
2809 if (unlikely(uf)) {
2810 /*
2811 * If userfaultfd_unmap_prep returns an error the vmas
2812 * will remain splitted, but userland will get a
2813 * highly unexpected error anyway. This is no
2814 * different than the case where the first of the two
2815 * __split_vma fails, but we don't undo the first
2816 * split, despite we could. This is unlikely enough
2817 * failure that it's not worth optimizing it for.
2818 */
2819 int error = userfaultfd_unmap_prep(vma, start, end, uf);
2820 if (error)
2821 return error;
2822 }
2823
2824 /*
2825 * unlock any mlock()ed ranges before detaching vmas
2826 */
2827 if (mm->locked_vm) {
2828 struct vm_area_struct *tmp = vma;
2829 while (tmp && tmp->vm_start < end) {
2830 if (tmp->vm_flags & VM_LOCKED) {
2831 mm->locked_vm -= vma_pages(tmp);
2832 munlock_vma_pages_all(tmp);
2833 }
2834
2835 tmp = tmp->vm_next;
2836 }
2837 }
2838
2839 /* Detach vmas from rbtree */
2840 detach_vmas_to_be_unmapped(mm, vma, prev, end);
2841
2842 if (downgrade)
2843 downgrade_write(&mm->mmap_sem);
2844
2845 unmap_region(mm, vma, prev, start, end);
2846
2847 /* Fix up all other VM information */
2848 remove_vma_list(mm, vma);
2849
2850 return downgrade ? 1 : 0;
2851}
2852
2853int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
2854 struct list_head *uf)
2855{
2856 return __do_munmap(mm, start, len, uf, false);
2857}
2858
2859static int __vm_munmap(unsigned long start, size_t len, bool downgrade)
2860{
2861 int ret;
2862 struct mm_struct *mm = current->mm;
2863 LIST_HEAD(uf);
2864
2865 if (down_write_killable(&mm->mmap_sem))
2866 return -EINTR;
2867
2868 ret = __do_munmap(mm, start, len, &uf, downgrade);
2869 /*
2870 * Returning 1 indicates mmap_sem is downgraded.
2871 * But 1 is not legal return value of vm_munmap() and munmap(), reset
2872 * it to 0 before return.
2873 */
2874 if (ret == 1) {
2875 up_read(&mm->mmap_sem);
2876 ret = 0;
2877 } else
2878 up_write(&mm->mmap_sem);
2879
2880 userfaultfd_unmap_complete(mm, &uf);
2881 return ret;
2882}
2883
2884int vm_munmap(unsigned long start, size_t len)
2885{
2886 return __vm_munmap(start, len, false);
2887}
2888EXPORT_SYMBOL(vm_munmap);
2889
2890SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2891{
2892 addr = untagged_addr(addr);
2893 profile_munmap(addr);
2894 return __vm_munmap(addr, len, true);
2895}
2896
2897
2898/*
2899 * Emulation of deprecated remap_file_pages() syscall.
2900 */
2901SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
2902 unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
2903{
2904
2905 struct mm_struct *mm = current->mm;
2906 struct vm_area_struct *vma;
2907 unsigned long populate = 0;
2908 unsigned long ret = -EINVAL;
2909 struct file *file;
2910
2911 pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.rst.\n",
2912 current->comm, current->pid);
2913
2914 if (prot)
2915 return ret;
2916 start = start & PAGE_MASK;
2917 size = size & PAGE_MASK;
2918
2919 if (start + size <= start)
2920 return ret;
2921
2922 /* Does pgoff wrap? */
2923 if (pgoff + (size >> PAGE_SHIFT) < pgoff)
2924 return ret;
2925
2926 if (down_write_killable(&mm->mmap_sem))
2927 return -EINTR;
2928
2929 vma = find_vma(mm, start);
2930
2931 if (!vma || !(vma->vm_flags & VM_SHARED))
2932 goto out;
2933
2934 if (start < vma->vm_start)
2935 goto out;
2936
2937 if (start + size > vma->vm_end) {
2938 struct vm_area_struct *next;
2939
2940 for (next = vma->vm_next; next; next = next->vm_next) {
2941 /* hole between vmas ? */
2942 if (next->vm_start != next->vm_prev->vm_end)
2943 goto out;
2944
2945 if (next->vm_file != vma->vm_file)
2946 goto out;
2947
2948 if (next->vm_flags != vma->vm_flags)
2949 goto out;
2950
2951 if (start + size <= next->vm_end)
2952 break;
2953 }
2954
2955 if (!next)
2956 goto out;
2957 }
2958
2959 prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
2960 prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
2961 prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
2962
2963 flags &= MAP_NONBLOCK;
2964 flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
2965 if (vma->vm_flags & VM_LOCKED) {
2966 struct vm_area_struct *tmp;
2967 flags |= MAP_LOCKED;
2968
2969 /* drop PG_Mlocked flag for over-mapped range */
2970 for (tmp = vma; tmp->vm_start >= start + size;
2971 tmp = tmp->vm_next) {
2972 /*
2973 * Split pmd and munlock page on the border
2974 * of the range.
2975 */
2976 vma_adjust_trans_huge(tmp, start, start + size, 0);
2977
2978 munlock_vma_pages_range(tmp,
2979 max(tmp->vm_start, start),
2980 min(tmp->vm_end, start + size));
2981 }
2982 }
2983
2984 file = get_file(vma->vm_file);
2985 ret = do_mmap_pgoff(vma->vm_file, start, size,
2986 prot, flags, pgoff, &populate, NULL);
2987 fput(file);
2988out:
2989 up_write(&mm->mmap_sem);
2990 if (populate)
2991 mm_populate(ret, populate);
2992 if (!IS_ERR_VALUE(ret))
2993 ret = 0;
2994 return ret;
2995}
2996
2997/*
2998 * this is really a simplified "do_mmap". it only handles
2999 * anonymous maps. eventually we may be able to do some
3000 * brk-specific accounting here.
3001 */
3002static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long flags, struct list_head *uf)
3003{
3004 struct mm_struct *mm = current->mm;
3005 struct vm_area_struct *vma, *prev;
3006 struct rb_node **rb_link, *rb_parent;
3007 pgoff_t pgoff = addr >> PAGE_SHIFT;
3008 int error;
3009
3010 /* Until we need other flags, refuse anything except VM_EXEC. */
3011 if ((flags & (~VM_EXEC)) != 0)
3012 return -EINVAL;
3013 flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
3014
3015 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
3016 if (offset_in_page(error))
3017 return error;
3018
3019 error = mlock_future_check(mm, mm->def_flags, len);
3020 if (error)
3021 return error;
3022
3023 /*
3024 * Clear old maps. this also does some error checking for us
3025 */
3026 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
3027 &rb_parent)) {
3028 if (do_munmap(mm, addr, len, uf))
3029 return -ENOMEM;
3030 }
3031
3032 /* Check against address space limits *after* clearing old maps... */
3033 if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))
3034 return -ENOMEM;
3035
3036 if (mm->map_count > sysctl_max_map_count)
3037 return -ENOMEM;
3038
3039 if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
3040 return -ENOMEM;
3041
3042 /* Can we just expand an old private anonymous mapping? */
3043 vma = vma_merge(mm, prev, addr, addr + len, flags,
3044 NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX);
3045 if (vma)
3046 goto out;
3047
3048 /*
3049 * create a vma struct for an anonymous mapping
3050 */
3051 vma = vm_area_alloc(mm);
3052 if (!vma) {
3053 vm_unacct_memory(len >> PAGE_SHIFT);
3054 return -ENOMEM;
3055 }
3056
3057 vma_set_anonymous(vma);
3058 vma->vm_start = addr;
3059 vma->vm_end = addr + len;
3060 vma->vm_pgoff = pgoff;
3061 vma->vm_flags = flags;
3062 vma->vm_page_prot = vm_get_page_prot(flags);
3063 vma_link(mm, vma, prev, rb_link, rb_parent);
3064out:
3065 perf_event_mmap(vma);
3066 mm->total_vm += len >> PAGE_SHIFT;
3067 mm->data_vm += len >> PAGE_SHIFT;
3068 if (flags & VM_LOCKED)
3069 mm->locked_vm += (len >> PAGE_SHIFT);
3070 vma->vm_flags |= VM_SOFTDIRTY;
3071 return 0;
3072}
3073
3074int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
3075{
3076 struct mm_struct *mm = current->mm;
3077 unsigned long len;
3078 int ret;
3079 bool populate;
3080 LIST_HEAD(uf);
3081
3082 len = PAGE_ALIGN(request);
3083 if (len < request)
3084 return -ENOMEM;
3085 if (!len)
3086 return 0;
3087
3088 if (down_write_killable(&mm->mmap_sem))
3089 return -EINTR;
3090
3091 ret = do_brk_flags(addr, len, flags, &uf);
3092 populate = ((mm->def_flags & VM_LOCKED) != 0);
3093 up_write(&mm->mmap_sem);
3094 userfaultfd_unmap_complete(mm, &uf);
3095 if (populate && !ret)
3096 mm_populate(addr, len);
3097 return ret;
3098}
3099EXPORT_SYMBOL(vm_brk_flags);
3100
3101int vm_brk(unsigned long addr, unsigned long len)
3102{
3103 return vm_brk_flags(addr, len, 0);
3104}
3105EXPORT_SYMBOL(vm_brk);
3106
3107/* Release all mmaps. */
3108void exit_mmap(struct mm_struct *mm)
3109{
3110 struct mmu_gather tlb;
3111 struct vm_area_struct *vma;
3112 unsigned long nr_accounted = 0;
3113
3114 /* mm's last user has gone, and its about to be pulled down */
3115 mmu_notifier_release(mm);
3116
3117 if (unlikely(mm_is_oom_victim(mm))) {
3118 /*
3119 * Manually reap the mm to free as much memory as possible.
3120 * Then, as the oom reaper does, set MMF_OOM_SKIP to disregard
3121 * this mm from further consideration. Taking mm->mmap_sem for
3122 * write after setting MMF_OOM_SKIP will guarantee that the oom
3123 * reaper will not run on this mm again after mmap_sem is
3124 * dropped.
3125 *
3126 * Nothing can be holding mm->mmap_sem here and the above call
3127 * to mmu_notifier_release(mm) ensures mmu notifier callbacks in
3128 * __oom_reap_task_mm() will not block.
3129 *
3130 * This needs to be done before calling munlock_vma_pages_all(),
3131 * which clears VM_LOCKED, otherwise the oom reaper cannot
3132 * reliably test it.
3133 */
3134 (void)__oom_reap_task_mm(mm);
3135
3136 set_bit(MMF_OOM_SKIP, &mm->flags);
3137 down_write(&mm->mmap_sem);
3138 up_write(&mm->mmap_sem);
3139 }
3140
3141 if (mm->locked_vm) {
3142 vma = mm->mmap;
3143 while (vma) {
3144 if (vma->vm_flags & VM_LOCKED)
3145 munlock_vma_pages_all(vma);
3146 vma = vma->vm_next;
3147 }
3148 }
3149
3150 arch_exit_mmap(mm);
3151
3152 vma = mm->mmap;
3153 if (!vma) /* Can happen if dup_mmap() received an OOM */
3154 return;
3155
3156 lru_add_drain();
3157 flush_cache_mm(mm);
3158 tlb_gather_mmu(&tlb, mm, 0, -1);
3159 /* update_hiwater_rss(mm) here? but nobody should be looking */
3160 /* Use -1 here to ensure all VMAs in the mm are unmapped */
3161 unmap_vmas(&tlb, vma, 0, -1);
3162 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
3163 tlb_finish_mmu(&tlb, 0, -1);
3164
3165 /*
3166 * Walk the list again, actually closing and freeing it,
3167 * with preemption enabled, without holding any MM locks.
3168 */
3169 while (vma) {
3170 if (vma->vm_flags & VM_ACCOUNT)
3171 nr_accounted += vma_pages(vma);
3172 vma = remove_vma(vma);
3173 }
3174 vm_unacct_memory(nr_accounted);
3175}
3176
3177/* Insert vm structure into process list sorted by address
3178 * and into the inode's i_mmap tree. If vm_file is non-NULL
3179 * then i_mmap_rwsem is taken here.
3180 */
3181int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
3182{
3183 struct vm_area_struct *prev;
3184 struct rb_node **rb_link, *rb_parent;
3185
3186 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
3187 &prev, &rb_link, &rb_parent))
3188 return -ENOMEM;
3189 if ((vma->vm_flags & VM_ACCOUNT) &&
3190 security_vm_enough_memory_mm(mm, vma_pages(vma)))
3191 return -ENOMEM;
3192
3193 /*
3194 * The vm_pgoff of a purely anonymous vma should be irrelevant
3195 * until its first write fault, when page's anon_vma and index
3196 * are set. But now set the vm_pgoff it will almost certainly
3197 * end up with (unless mremap moves it elsewhere before that
3198 * first wfault), so /proc/pid/maps tells a consistent story.
3199 *
3200 * By setting it to reflect the virtual start address of the
3201 * vma, merges and splits can happen in a seamless way, just
3202 * using the existing file pgoff checks and manipulations.
3203 * Similarly in do_mmap_pgoff and in do_brk.
3204 */
3205 if (vma_is_anonymous(vma)) {
3206 BUG_ON(vma->anon_vma);
3207 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
3208 }
3209
3210 vma_link(mm, vma, prev, rb_link, rb_parent);
3211 return 0;
3212}
3213
3214/*
3215 * Copy the vma structure to a new location in the same mm,
3216 * prior to moving page table entries, to effect an mremap move.
3217 */
3218struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
3219 unsigned long addr, unsigned long len, pgoff_t pgoff,
3220 bool *need_rmap_locks)
3221{
3222 struct vm_area_struct *vma = *vmap;
3223 unsigned long vma_start = vma->vm_start;
3224 struct mm_struct *mm = vma->vm_mm;
3225 struct vm_area_struct *new_vma, *prev;
3226 struct rb_node **rb_link, *rb_parent;
3227 bool faulted_in_anon_vma = true;
3228
3229 /*
3230 * If anonymous vma has not yet been faulted, update new pgoff
3231 * to match new location, to increase its chance of merging.
3232 */
3233 if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
3234 pgoff = addr >> PAGE_SHIFT;
3235 faulted_in_anon_vma = false;
3236 }
3237
3238 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
3239 return NULL; /* should never get here */
3240 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
3241 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
3242 vma->vm_userfaultfd_ctx);
3243 if (new_vma) {
3244 /*
3245 * Source vma may have been merged into new_vma
3246 */
3247 if (unlikely(vma_start >= new_vma->vm_start &&
3248 vma_start < new_vma->vm_end)) {
3249 /*
3250 * The only way we can get a vma_merge with
3251 * self during an mremap is if the vma hasn't
3252 * been faulted in yet and we were allowed to
3253 * reset the dst vma->vm_pgoff to the
3254 * destination address of the mremap to allow
3255 * the merge to happen. mremap must change the
3256 * vm_pgoff linearity between src and dst vmas
3257 * (in turn preventing a vma_merge) to be
3258 * safe. It is only safe to keep the vm_pgoff
3259 * linear if there are no pages mapped yet.
3260 */
3261 VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
3262 *vmap = vma = new_vma;
3263 }
3264 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
3265 } else {
3266 new_vma = vm_area_dup(vma);
3267 if (!new_vma)
3268 goto out;
3269 new_vma->vm_start = addr;
3270 new_vma->vm_end = addr + len;
3271 new_vma->vm_pgoff = pgoff;
3272 if (vma_dup_policy(vma, new_vma))
3273 goto out_free_vma;
3274 if (anon_vma_clone(new_vma, vma))
3275 goto out_free_mempol;
3276 if (new_vma->vm_file)
3277 get_file(new_vma->vm_file);
3278 if (new_vma->vm_ops && new_vma->vm_ops->open)
3279 new_vma->vm_ops->open(new_vma);
3280 vma_link(mm, new_vma, prev, rb_link, rb_parent);
3281 *need_rmap_locks = false;
3282 }
3283 return new_vma;
3284
3285out_free_mempol:
3286 mpol_put(vma_policy(new_vma));
3287out_free_vma:
3288 vm_area_free(new_vma);
3289out:
3290 return NULL;
3291}
3292
3293/*
3294 * Return true if the calling process may expand its vm space by the passed
3295 * number of pages
3296 */
3297bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
3298{
3299 if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
3300 return false;
3301
3302 if (is_data_mapping(flags) &&
3303 mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
3304 /* Workaround for Valgrind */
3305 if (rlimit(RLIMIT_DATA) == 0 &&
3306 mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
3307 return true;
3308
3309 pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n",
3310 current->comm, current->pid,
3311 (mm->data_vm + npages) << PAGE_SHIFT,
3312 rlimit(RLIMIT_DATA),
3313 ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data");
3314
3315 if (!ignore_rlimit_data)
3316 return false;
3317 }
3318
3319 return true;
3320}
3321
3322void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
3323{
3324 mm->total_vm += npages;
3325
3326 if (is_exec_mapping(flags))
3327 mm->exec_vm += npages;
3328 else if (is_stack_mapping(flags))
3329 mm->stack_vm += npages;
3330 else if (is_data_mapping(flags))
3331 mm->data_vm += npages;
3332}
3333
3334static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
3335
3336/*
3337 * Having a close hook prevents vma merging regardless of flags.
3338 */
3339static void special_mapping_close(struct vm_area_struct *vma)
3340{
3341}
3342
3343static const char *special_mapping_name(struct vm_area_struct *vma)
3344{
3345 return ((struct vm_special_mapping *)vma->vm_private_data)->name;
3346}
3347
3348static int special_mapping_mremap(struct vm_area_struct *new_vma)
3349{
3350 struct vm_special_mapping *sm = new_vma->vm_private_data;
3351
3352 if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
3353 return -EFAULT;
3354
3355 if (sm->mremap)
3356 return sm->mremap(sm, new_vma);
3357
3358 return 0;
3359}
3360
3361static const struct vm_operations_struct special_mapping_vmops = {
3362 .close = special_mapping_close,
3363 .fault = special_mapping_fault,
3364 .mremap = special_mapping_mremap,
3365 .name = special_mapping_name,
3366};
3367
3368static const struct vm_operations_struct legacy_special_mapping_vmops = {
3369 .close = special_mapping_close,
3370 .fault = special_mapping_fault,
3371};
3372
3373static vm_fault_t special_mapping_fault(struct vm_fault *vmf)
3374{
3375 struct vm_area_struct *vma = vmf->vma;
3376 pgoff_t pgoff;
3377 struct page **pages;
3378
3379 if (vma->vm_ops == &legacy_special_mapping_vmops) {
3380 pages = vma->vm_private_data;
3381 } else {
3382 struct vm_special_mapping *sm = vma->vm_private_data;
3383
3384 if (sm->fault)
3385 return sm->fault(sm, vmf->vma, vmf);
3386
3387 pages = sm->pages;
3388 }
3389
3390 for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
3391 pgoff--;
3392
3393 if (*pages) {
3394 struct page *page = *pages;
3395 get_page(page);
3396 vmf->page = page;
3397 return 0;
3398 }
3399
3400 return VM_FAULT_SIGBUS;
3401}
3402
3403static struct vm_area_struct *__install_special_mapping(
3404 struct mm_struct *mm,
3405 unsigned long addr, unsigned long len,
3406 unsigned long vm_flags, void *priv,
3407 const struct vm_operations_struct *ops)
3408{
3409 int ret;
3410 struct vm_area_struct *vma;
3411
3412 vma = vm_area_alloc(mm);
3413 if (unlikely(vma == NULL))
3414 return ERR_PTR(-ENOMEM);
3415
3416 vma->vm_start = addr;
3417 vma->vm_end = addr + len;
3418
3419 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
3420 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
3421
3422 vma->vm_ops = ops;
3423 vma->vm_private_data = priv;
3424
3425 ret = insert_vm_struct(mm, vma);
3426 if (ret)
3427 goto out;
3428
3429 vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
3430
3431 perf_event_mmap(vma);
3432
3433 return vma;
3434
3435out:
3436 vm_area_free(vma);
3437 return ERR_PTR(ret);
3438}
3439
3440bool vma_is_special_mapping(const struct vm_area_struct *vma,
3441 const struct vm_special_mapping *sm)
3442{
3443 return vma->vm_private_data == sm &&
3444 (vma->vm_ops == &special_mapping_vmops ||
3445 vma->vm_ops == &legacy_special_mapping_vmops);
3446}
3447
3448/*
3449 * Called with mm->mmap_sem held for writing.
3450 * Insert a new vma covering the given region, with the given flags.
3451 * Its pages are supplied by the given array of struct page *.
3452 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
3453 * The region past the last page supplied will always produce SIGBUS.
3454 * The array pointer and the pages it points to are assumed to stay alive
3455 * for as long as this mapping might exist.
3456 */
3457struct vm_area_struct *_install_special_mapping(
3458 struct mm_struct *mm,
3459 unsigned long addr, unsigned long len,
3460 unsigned long vm_flags, const struct vm_special_mapping *spec)
3461{
3462 return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
3463 &special_mapping_vmops);
3464}
3465
3466int install_special_mapping(struct mm_struct *mm,
3467 unsigned long addr, unsigned long len,
3468 unsigned long vm_flags, struct page **pages)
3469{
3470 struct vm_area_struct *vma = __install_special_mapping(
3471 mm, addr, len, vm_flags, (void *)pages,
3472 &legacy_special_mapping_vmops);
3473
3474 return PTR_ERR_OR_ZERO(vma);
3475}
3476
3477static DEFINE_MUTEX(mm_all_locks_mutex);
3478
3479static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
3480{
3481 if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
3482 /*
3483 * The LSB of head.next can't change from under us
3484 * because we hold the mm_all_locks_mutex.
3485 */
3486 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
3487 /*
3488 * We can safely modify head.next after taking the
3489 * anon_vma->root->rwsem. If some other vma in this mm shares
3490 * the same anon_vma we won't take it again.
3491 *
3492 * No need of atomic instructions here, head.next
3493 * can't change from under us thanks to the
3494 * anon_vma->root->rwsem.
3495 */
3496 if (__test_and_set_bit(0, (unsigned long *)
3497 &anon_vma->root->rb_root.rb_root.rb_node))
3498 BUG();
3499 }
3500}
3501
3502static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
3503{
3504 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3505 /*
3506 * AS_MM_ALL_LOCKS can't change from under us because
3507 * we hold the mm_all_locks_mutex.
3508 *
3509 * Operations on ->flags have to be atomic because
3510 * even if AS_MM_ALL_LOCKS is stable thanks to the
3511 * mm_all_locks_mutex, there may be other cpus
3512 * changing other bitflags in parallel to us.
3513 */
3514 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
3515 BUG();
3516 down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem);
3517 }
3518}
3519
3520/*
3521 * This operation locks against the VM for all pte/vma/mm related
3522 * operations that could ever happen on a certain mm. This includes
3523 * vmtruncate, try_to_unmap, and all page faults.
3524 *
3525 * The caller must take the mmap_sem in write mode before calling
3526 * mm_take_all_locks(). The caller isn't allowed to release the
3527 * mmap_sem until mm_drop_all_locks() returns.
3528 *
3529 * mmap_sem in write mode is required in order to block all operations
3530 * that could modify pagetables and free pages without need of
3531 * altering the vma layout. It's also needed in write mode to avoid new
3532 * anon_vmas to be associated with existing vmas.
3533 *
3534 * A single task can't take more than one mm_take_all_locks() in a row
3535 * or it would deadlock.
3536 *
3537 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3538 * mapping->flags avoid to take the same lock twice, if more than one
3539 * vma in this mm is backed by the same anon_vma or address_space.
3540 *
3541 * We take locks in following order, accordingly to comment at beginning
3542 * of mm/rmap.c:
3543 * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
3544 * hugetlb mapping);
3545 * - all i_mmap_rwsem locks;
3546 * - all anon_vma->rwseml
3547 *
3548 * We can take all locks within these types randomly because the VM code
3549 * doesn't nest them and we protected from parallel mm_take_all_locks() by
3550 * mm_all_locks_mutex.
3551 *
3552 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3553 * that may have to take thousand of locks.
3554 *
3555 * mm_take_all_locks() can fail if it's interrupted by signals.
3556 */
3557int mm_take_all_locks(struct mm_struct *mm)
3558{
3559 struct vm_area_struct *vma;
3560 struct anon_vma_chain *avc;
3561
3562 BUG_ON(down_read_trylock(&mm->mmap_sem));
3563
3564 mutex_lock(&mm_all_locks_mutex);
3565
3566 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3567 if (signal_pending(current))
3568 goto out_unlock;
3569 if (vma->vm_file && vma->vm_file->f_mapping &&
3570 is_vm_hugetlb_page(vma))
3571 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3572 }
3573
3574 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3575 if (signal_pending(current))
3576 goto out_unlock;
3577 if (vma->vm_file && vma->vm_file->f_mapping &&
3578 !is_vm_hugetlb_page(vma))
3579 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3580 }
3581
3582 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3583 if (signal_pending(current))
3584 goto out_unlock;
3585 if (vma->anon_vma)
3586 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3587 vm_lock_anon_vma(mm, avc->anon_vma);
3588 }
3589
3590 return 0;
3591
3592out_unlock:
3593 mm_drop_all_locks(mm);
3594 return -EINTR;
3595}
3596
3597static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3598{
3599 if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
3600 /*
3601 * The LSB of head.next can't change to 0 from under
3602 * us because we hold the mm_all_locks_mutex.
3603 *
3604 * We must however clear the bitflag before unlocking
3605 * the vma so the users using the anon_vma->rb_root will
3606 * never see our bitflag.
3607 *
3608 * No need of atomic instructions here, head.next
3609 * can't change from under us until we release the
3610 * anon_vma->root->rwsem.
3611 */
3612 if (!__test_and_clear_bit(0, (unsigned long *)
3613 &anon_vma->root->rb_root.rb_root.rb_node))
3614 BUG();
3615 anon_vma_unlock_write(anon_vma);
3616 }
3617}
3618
3619static void vm_unlock_mapping(struct address_space *mapping)
3620{
3621 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3622 /*
3623 * AS_MM_ALL_LOCKS can't change to 0 from under us
3624 * because we hold the mm_all_locks_mutex.
3625 */
3626 i_mmap_unlock_write(mapping);
3627 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
3628 &mapping->flags))
3629 BUG();
3630 }
3631}
3632
3633/*
3634 * The mmap_sem cannot be released by the caller until
3635 * mm_drop_all_locks() returns.
3636 */
3637void mm_drop_all_locks(struct mm_struct *mm)
3638{
3639 struct vm_area_struct *vma;
3640 struct anon_vma_chain *avc;
3641
3642 BUG_ON(down_read_trylock(&mm->mmap_sem));
3643 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3644
3645 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3646 if (vma->anon_vma)
3647 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3648 vm_unlock_anon_vma(avc->anon_vma);
3649 if (vma->vm_file && vma->vm_file->f_mapping)
3650 vm_unlock_mapping(vma->vm_file->f_mapping);
3651 }
3652
3653 mutex_unlock(&mm_all_locks_mutex);
3654}
3655
3656/*
3657 * initialise the percpu counter for VM
3658 */
3659void __init mmap_init(void)
3660{
3661 int ret;
3662
3663 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
3664 VM_BUG_ON(ret);
3665}
3666
3667/*
3668 * Initialise sysctl_user_reserve_kbytes.
3669 *
3670 * This is intended to prevent a user from starting a single memory hogging
3671 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3672 * mode.
3673 *
3674 * The default value is min(3% of free memory, 128MB)
3675 * 128MB is enough to recover with sshd/login, bash, and top/kill.
3676 */
3677static int init_user_reserve(void)
3678{
3679 unsigned long free_kbytes;
3680
3681 free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3682
3683 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
3684 return 0;
3685}
3686subsys_initcall(init_user_reserve);
3687
3688/*
3689 * Initialise sysctl_admin_reserve_kbytes.
3690 *
3691 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3692 * to log in and kill a memory hogging process.
3693 *
3694 * Systems with more than 256MB will reserve 8MB, enough to recover
3695 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3696 * only reserve 3% of free pages by default.
3697 */
3698static int init_admin_reserve(void)
3699{
3700 unsigned long free_kbytes;
3701
3702 free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3703
3704 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
3705 return 0;
3706}
3707subsys_initcall(init_admin_reserve);
3708
3709/*
3710 * Reinititalise user and admin reserves if memory is added or removed.
3711 *
3712 * The default user reserve max is 128MB, and the default max for the
3713 * admin reserve is 8MB. These are usually, but not always, enough to
3714 * enable recovery from a memory hogging process using login/sshd, a shell,
3715 * and tools like top. It may make sense to increase or even disable the
3716 * reserve depending on the existence of swap or variations in the recovery
3717 * tools. So, the admin may have changed them.
3718 *
3719 * If memory is added and the reserves have been eliminated or increased above
3720 * the default max, then we'll trust the admin.
3721 *
3722 * If memory is removed and there isn't enough free memory, then we
3723 * need to reset the reserves.
3724 *
3725 * Otherwise keep the reserve set by the admin.
3726 */
3727static int reserve_mem_notifier(struct notifier_block *nb,
3728 unsigned long action, void *data)
3729{
3730 unsigned long tmp, free_kbytes;
3731
3732 switch (action) {
3733 case MEM_ONLINE:
3734 /* Default max is 128MB. Leave alone if modified by operator. */
3735 tmp = sysctl_user_reserve_kbytes;
3736 if (0 < tmp && tmp < (1UL << 17))
3737 init_user_reserve();
3738
3739 /* Default max is 8MB. Leave alone if modified by operator. */
3740 tmp = sysctl_admin_reserve_kbytes;
3741 if (0 < tmp && tmp < (1UL << 13))
3742 init_admin_reserve();
3743
3744 break;
3745 case MEM_OFFLINE:
3746 free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3747
3748 if (sysctl_user_reserve_kbytes > free_kbytes) {
3749 init_user_reserve();
3750 pr_info("vm.user_reserve_kbytes reset to %lu\n",
3751 sysctl_user_reserve_kbytes);
3752 }
3753
3754 if (sysctl_admin_reserve_kbytes > free_kbytes) {
3755 init_admin_reserve();
3756 pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3757 sysctl_admin_reserve_kbytes);
3758 }
3759 break;
3760 default:
3761 break;
3762 }
3763 return NOTIFY_OK;
3764}
3765
3766static struct notifier_block reserve_mem_nb = {
3767 .notifier_call = reserve_mem_notifier,
3768};
3769
3770static int __meminit init_reserve_notifier(void)
3771{
3772 if (register_hotmemory_notifier(&reserve_mem_nb))
3773 pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3774
3775 return 0;
3776}
3777subsys_initcall(init_reserve_notifier);
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/kernel.h>
10#include <linux/slab.h>
11#include <linux/backing-dev.h>
12#include <linux/mm.h>
13#include <linux/vmacache.h>
14#include <linux/shm.h>
15#include <linux/mman.h>
16#include <linux/pagemap.h>
17#include <linux/swap.h>
18#include <linux/syscalls.h>
19#include <linux/capability.h>
20#include <linux/init.h>
21#include <linux/file.h>
22#include <linux/fs.h>
23#include <linux/personality.h>
24#include <linux/security.h>
25#include <linux/hugetlb.h>
26#include <linux/profile.h>
27#include <linux/export.h>
28#include <linux/mount.h>
29#include <linux/mempolicy.h>
30#include <linux/rmap.h>
31#include <linux/mmu_notifier.h>
32#include <linux/perf_event.h>
33#include <linux/audit.h>
34#include <linux/khugepaged.h>
35#include <linux/uprobes.h>
36#include <linux/rbtree_augmented.h>
37#include <linux/sched/sysctl.h>
38#include <linux/notifier.h>
39#include <linux/memory.h>
40
41#include <asm/uaccess.h>
42#include <asm/cacheflush.h>
43#include <asm/tlb.h>
44#include <asm/mmu_context.h>
45
46#include "internal.h"
47
48#ifndef arch_mmap_check
49#define arch_mmap_check(addr, len, flags) (0)
50#endif
51
52#ifndef arch_rebalance_pgtables
53#define arch_rebalance_pgtables(addr, len) (addr)
54#endif
55
56static void unmap_region(struct mm_struct *mm,
57 struct vm_area_struct *vma, struct vm_area_struct *prev,
58 unsigned long start, unsigned long end);
59
60/* description of effects of mapping type and prot in current implementation.
61 * this is due to the limited x86 page protection hardware. The expected
62 * behavior is in parens:
63 *
64 * map_type prot
65 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
66 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
67 * w: (no) no w: (no) no w: (yes) yes w: (no) no
68 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
69 *
70 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
71 * w: (no) no w: (no) no w: (copy) copy w: (no) no
72 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
73 *
74 */
75pgprot_t protection_map[16] = {
76 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
77 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
78};
79
80pgprot_t vm_get_page_prot(unsigned long vm_flags)
81{
82 return __pgprot(pgprot_val(protection_map[vm_flags &
83 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
84 pgprot_val(arch_vm_get_page_prot(vm_flags)));
85}
86EXPORT_SYMBOL(vm_get_page_prot);
87
88int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; /* heuristic overcommit */
89int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */
90unsigned long sysctl_overcommit_kbytes __read_mostly;
91int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
92unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
93unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
94/*
95 * Make sure vm_committed_as in one cacheline and not cacheline shared with
96 * other variables. It can be updated by several CPUs frequently.
97 */
98struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
99
100/*
101 * The global memory commitment made in the system can be a metric
102 * that can be used to drive ballooning decisions when Linux is hosted
103 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
104 * balancing memory across competing virtual machines that are hosted.
105 * Several metrics drive this policy engine including the guest reported
106 * memory commitment.
107 */
108unsigned long vm_memory_committed(void)
109{
110 return percpu_counter_read_positive(&vm_committed_as);
111}
112EXPORT_SYMBOL_GPL(vm_memory_committed);
113
114/*
115 * Check that a process has enough memory to allocate a new virtual
116 * mapping. 0 means there is enough memory for the allocation to
117 * succeed and -ENOMEM implies there is not.
118 *
119 * We currently support three overcommit policies, which are set via the
120 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
121 *
122 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
123 * Additional code 2002 Jul 20 by Robert Love.
124 *
125 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
126 *
127 * Note this is a helper function intended to be used by LSMs which
128 * wish to use this logic.
129 */
130int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
131{
132 unsigned long free, allowed, reserve;
133
134 vm_acct_memory(pages);
135
136 /*
137 * Sometimes we want to use more memory than we have
138 */
139 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
140 return 0;
141
142 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
143 free = global_page_state(NR_FREE_PAGES);
144 free += global_page_state(NR_FILE_PAGES);
145
146 /*
147 * shmem pages shouldn't be counted as free in this
148 * case, they can't be purged, only swapped out, and
149 * that won't affect the overall amount of available
150 * memory in the system.
151 */
152 free -= global_page_state(NR_SHMEM);
153
154 free += get_nr_swap_pages();
155
156 /*
157 * Any slabs which are created with the
158 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
159 * which are reclaimable, under pressure. The dentry
160 * cache and most inode caches should fall into this
161 */
162 free += global_page_state(NR_SLAB_RECLAIMABLE);
163
164 /*
165 * Leave reserved pages. The pages are not for anonymous pages.
166 */
167 if (free <= totalreserve_pages)
168 goto error;
169 else
170 free -= totalreserve_pages;
171
172 /*
173 * Reserve some for root
174 */
175 if (!cap_sys_admin)
176 free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
177
178 if (free > pages)
179 return 0;
180
181 goto error;
182 }
183
184 allowed = vm_commit_limit();
185 /*
186 * Reserve some for root
187 */
188 if (!cap_sys_admin)
189 allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
190
191 /*
192 * Don't let a single process grow so big a user can't recover
193 */
194 if (mm) {
195 reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
196 allowed -= min(mm->total_vm / 32, reserve);
197 }
198
199 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
200 return 0;
201error:
202 vm_unacct_memory(pages);
203
204 return -ENOMEM;
205}
206
207/*
208 * Requires inode->i_mapping->i_mmap_mutex
209 */
210static void __remove_shared_vm_struct(struct vm_area_struct *vma,
211 struct file *file, struct address_space *mapping)
212{
213 if (vma->vm_flags & VM_DENYWRITE)
214 atomic_inc(&file_inode(file)->i_writecount);
215 if (vma->vm_flags & VM_SHARED)
216 mapping->i_mmap_writable--;
217
218 flush_dcache_mmap_lock(mapping);
219 if (unlikely(vma->vm_flags & VM_NONLINEAR))
220 list_del_init(&vma->shared.nonlinear);
221 else
222 vma_interval_tree_remove(vma, &mapping->i_mmap);
223 flush_dcache_mmap_unlock(mapping);
224}
225
226/*
227 * Unlink a file-based vm structure from its interval tree, to hide
228 * vma from rmap and vmtruncate before freeing its page tables.
229 */
230void unlink_file_vma(struct vm_area_struct *vma)
231{
232 struct file *file = vma->vm_file;
233
234 if (file) {
235 struct address_space *mapping = file->f_mapping;
236 mutex_lock(&mapping->i_mmap_mutex);
237 __remove_shared_vm_struct(vma, file, mapping);
238 mutex_unlock(&mapping->i_mmap_mutex);
239 }
240}
241
242/*
243 * Close a vm structure and free it, returning the next.
244 */
245static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
246{
247 struct vm_area_struct *next = vma->vm_next;
248
249 might_sleep();
250 if (vma->vm_ops && vma->vm_ops->close)
251 vma->vm_ops->close(vma);
252 if (vma->vm_file)
253 fput(vma->vm_file);
254 mpol_put(vma_policy(vma));
255 kmem_cache_free(vm_area_cachep, vma);
256 return next;
257}
258
259static unsigned long do_brk(unsigned long addr, unsigned long len);
260
261SYSCALL_DEFINE1(brk, unsigned long, brk)
262{
263 unsigned long rlim, retval;
264 unsigned long newbrk, oldbrk;
265 struct mm_struct *mm = current->mm;
266 unsigned long min_brk;
267 bool populate;
268
269 down_write(&mm->mmap_sem);
270
271#ifdef CONFIG_COMPAT_BRK
272 /*
273 * CONFIG_COMPAT_BRK can still be overridden by setting
274 * randomize_va_space to 2, which will still cause mm->start_brk
275 * to be arbitrarily shifted
276 */
277 if (current->brk_randomized)
278 min_brk = mm->start_brk;
279 else
280 min_brk = mm->end_data;
281#else
282 min_brk = mm->start_brk;
283#endif
284 if (brk < min_brk)
285 goto out;
286
287 /*
288 * Check against rlimit here. If this check is done later after the test
289 * of oldbrk with newbrk then it can escape the test and let the data
290 * segment grow beyond its set limit the in case where the limit is
291 * not page aligned -Ram Gupta
292 */
293 rlim = rlimit(RLIMIT_DATA);
294 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
295 (mm->end_data - mm->start_data) > rlim)
296 goto out;
297
298 newbrk = PAGE_ALIGN(brk);
299 oldbrk = PAGE_ALIGN(mm->brk);
300 if (oldbrk == newbrk)
301 goto set_brk;
302
303 /* Always allow shrinking brk. */
304 if (brk <= mm->brk) {
305 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
306 goto set_brk;
307 goto out;
308 }
309
310 /* Check against existing mmap mappings. */
311 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
312 goto out;
313
314 /* Ok, looks good - let it rip. */
315 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
316 goto out;
317
318set_brk:
319 mm->brk = brk;
320 populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
321 up_write(&mm->mmap_sem);
322 if (populate)
323 mm_populate(oldbrk, newbrk - oldbrk);
324 return brk;
325
326out:
327 retval = mm->brk;
328 up_write(&mm->mmap_sem);
329 return retval;
330}
331
332static long vma_compute_subtree_gap(struct vm_area_struct *vma)
333{
334 unsigned long max, subtree_gap;
335 max = vma->vm_start;
336 if (vma->vm_prev)
337 max -= vma->vm_prev->vm_end;
338 if (vma->vm_rb.rb_left) {
339 subtree_gap = rb_entry(vma->vm_rb.rb_left,
340 struct vm_area_struct, vm_rb)->rb_subtree_gap;
341 if (subtree_gap > max)
342 max = subtree_gap;
343 }
344 if (vma->vm_rb.rb_right) {
345 subtree_gap = rb_entry(vma->vm_rb.rb_right,
346 struct vm_area_struct, vm_rb)->rb_subtree_gap;
347 if (subtree_gap > max)
348 max = subtree_gap;
349 }
350 return max;
351}
352
353#ifdef CONFIG_DEBUG_VM_RB
354static int browse_rb(struct rb_root *root)
355{
356 int i = 0, j, bug = 0;
357 struct rb_node *nd, *pn = NULL;
358 unsigned long prev = 0, pend = 0;
359
360 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
361 struct vm_area_struct *vma;
362 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
363 if (vma->vm_start < prev) {
364 printk("vm_start %lx prev %lx\n", vma->vm_start, prev);
365 bug = 1;
366 }
367 if (vma->vm_start < pend) {
368 printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
369 bug = 1;
370 }
371 if (vma->vm_start > vma->vm_end) {
372 printk("vm_end %lx < vm_start %lx\n",
373 vma->vm_end, vma->vm_start);
374 bug = 1;
375 }
376 if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
377 printk("free gap %lx, correct %lx\n",
378 vma->rb_subtree_gap,
379 vma_compute_subtree_gap(vma));
380 bug = 1;
381 }
382 i++;
383 pn = nd;
384 prev = vma->vm_start;
385 pend = vma->vm_end;
386 }
387 j = 0;
388 for (nd = pn; nd; nd = rb_prev(nd))
389 j++;
390 if (i != j) {
391 printk("backwards %d, forwards %d\n", j, i);
392 bug = 1;
393 }
394 return bug ? -1 : i;
395}
396
397static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
398{
399 struct rb_node *nd;
400
401 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
402 struct vm_area_struct *vma;
403 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
404 BUG_ON(vma != ignore &&
405 vma->rb_subtree_gap != vma_compute_subtree_gap(vma));
406 }
407}
408
409static void validate_mm(struct mm_struct *mm)
410{
411 int bug = 0;
412 int i = 0;
413 unsigned long highest_address = 0;
414 struct vm_area_struct *vma = mm->mmap;
415 while (vma) {
416 struct anon_vma_chain *avc;
417 vma_lock_anon_vma(vma);
418 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
419 anon_vma_interval_tree_verify(avc);
420 vma_unlock_anon_vma(vma);
421 highest_address = vma->vm_end;
422 vma = vma->vm_next;
423 i++;
424 }
425 if (i != mm->map_count) {
426 printk("map_count %d vm_next %d\n", mm->map_count, i);
427 bug = 1;
428 }
429 if (highest_address != mm->highest_vm_end) {
430 printk("mm->highest_vm_end %lx, found %lx\n",
431 mm->highest_vm_end, highest_address);
432 bug = 1;
433 }
434 i = browse_rb(&mm->mm_rb);
435 if (i != mm->map_count) {
436 printk("map_count %d rb %d\n", mm->map_count, i);
437 bug = 1;
438 }
439 BUG_ON(bug);
440}
441#else
442#define validate_mm_rb(root, ignore) do { } while (0)
443#define validate_mm(mm) do { } while (0)
444#endif
445
446RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb,
447 unsigned long, rb_subtree_gap, vma_compute_subtree_gap)
448
449/*
450 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
451 * vma->vm_prev->vm_end values changed, without modifying the vma's position
452 * in the rbtree.
453 */
454static void vma_gap_update(struct vm_area_struct *vma)
455{
456 /*
457 * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
458 * function that does exacltly what we want.
459 */
460 vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
461}
462
463static inline void vma_rb_insert(struct vm_area_struct *vma,
464 struct rb_root *root)
465{
466 /* All rb_subtree_gap values must be consistent prior to insertion */
467 validate_mm_rb(root, NULL);
468
469 rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
470}
471
472static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
473{
474 /*
475 * All rb_subtree_gap values must be consistent prior to erase,
476 * with the possible exception of the vma being erased.
477 */
478 validate_mm_rb(root, vma);
479
480 /*
481 * Note rb_erase_augmented is a fairly large inline function,
482 * so make sure we instantiate it only once with our desired
483 * augmented rbtree callbacks.
484 */
485 rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
486}
487
488/*
489 * vma has some anon_vma assigned, and is already inserted on that
490 * anon_vma's interval trees.
491 *
492 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
493 * vma must be removed from the anon_vma's interval trees using
494 * anon_vma_interval_tree_pre_update_vma().
495 *
496 * After the update, the vma will be reinserted using
497 * anon_vma_interval_tree_post_update_vma().
498 *
499 * The entire update must be protected by exclusive mmap_sem and by
500 * the root anon_vma's mutex.
501 */
502static inline void
503anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
504{
505 struct anon_vma_chain *avc;
506
507 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
508 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
509}
510
511static inline void
512anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
513{
514 struct anon_vma_chain *avc;
515
516 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
517 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
518}
519
520static int find_vma_links(struct mm_struct *mm, unsigned long addr,
521 unsigned long end, struct vm_area_struct **pprev,
522 struct rb_node ***rb_link, struct rb_node **rb_parent)
523{
524 struct rb_node **__rb_link, *__rb_parent, *rb_prev;
525
526 __rb_link = &mm->mm_rb.rb_node;
527 rb_prev = __rb_parent = NULL;
528
529 while (*__rb_link) {
530 struct vm_area_struct *vma_tmp;
531
532 __rb_parent = *__rb_link;
533 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
534
535 if (vma_tmp->vm_end > addr) {
536 /* Fail if an existing vma overlaps the area */
537 if (vma_tmp->vm_start < end)
538 return -ENOMEM;
539 __rb_link = &__rb_parent->rb_left;
540 } else {
541 rb_prev = __rb_parent;
542 __rb_link = &__rb_parent->rb_right;
543 }
544 }
545
546 *pprev = NULL;
547 if (rb_prev)
548 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
549 *rb_link = __rb_link;
550 *rb_parent = __rb_parent;
551 return 0;
552}
553
554static unsigned long count_vma_pages_range(struct mm_struct *mm,
555 unsigned long addr, unsigned long end)
556{
557 unsigned long nr_pages = 0;
558 struct vm_area_struct *vma;
559
560 /* Find first overlaping mapping */
561 vma = find_vma_intersection(mm, addr, end);
562 if (!vma)
563 return 0;
564
565 nr_pages = (min(end, vma->vm_end) -
566 max(addr, vma->vm_start)) >> PAGE_SHIFT;
567
568 /* Iterate over the rest of the overlaps */
569 for (vma = vma->vm_next; vma; vma = vma->vm_next) {
570 unsigned long overlap_len;
571
572 if (vma->vm_start > end)
573 break;
574
575 overlap_len = min(end, vma->vm_end) - vma->vm_start;
576 nr_pages += overlap_len >> PAGE_SHIFT;
577 }
578
579 return nr_pages;
580}
581
582void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
583 struct rb_node **rb_link, struct rb_node *rb_parent)
584{
585 /* Update tracking information for the gap following the new vma. */
586 if (vma->vm_next)
587 vma_gap_update(vma->vm_next);
588 else
589 mm->highest_vm_end = vma->vm_end;
590
591 /*
592 * vma->vm_prev wasn't known when we followed the rbtree to find the
593 * correct insertion point for that vma. As a result, we could not
594 * update the vma vm_rb parents rb_subtree_gap values on the way down.
595 * So, we first insert the vma with a zero rb_subtree_gap value
596 * (to be consistent with what we did on the way down), and then
597 * immediately update the gap to the correct value. Finally we
598 * rebalance the rbtree after all augmented values have been set.
599 */
600 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
601 vma->rb_subtree_gap = 0;
602 vma_gap_update(vma);
603 vma_rb_insert(vma, &mm->mm_rb);
604}
605
606static void __vma_link_file(struct vm_area_struct *vma)
607{
608 struct file *file;
609
610 file = vma->vm_file;
611 if (file) {
612 struct address_space *mapping = file->f_mapping;
613
614 if (vma->vm_flags & VM_DENYWRITE)
615 atomic_dec(&file_inode(file)->i_writecount);
616 if (vma->vm_flags & VM_SHARED)
617 mapping->i_mmap_writable++;
618
619 flush_dcache_mmap_lock(mapping);
620 if (unlikely(vma->vm_flags & VM_NONLINEAR))
621 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
622 else
623 vma_interval_tree_insert(vma, &mapping->i_mmap);
624 flush_dcache_mmap_unlock(mapping);
625 }
626}
627
628static void
629__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
630 struct vm_area_struct *prev, struct rb_node **rb_link,
631 struct rb_node *rb_parent)
632{
633 __vma_link_list(mm, vma, prev, rb_parent);
634 __vma_link_rb(mm, vma, rb_link, rb_parent);
635}
636
637static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
638 struct vm_area_struct *prev, struct rb_node **rb_link,
639 struct rb_node *rb_parent)
640{
641 struct address_space *mapping = NULL;
642
643 if (vma->vm_file)
644 mapping = vma->vm_file->f_mapping;
645
646 if (mapping)
647 mutex_lock(&mapping->i_mmap_mutex);
648
649 __vma_link(mm, vma, prev, rb_link, rb_parent);
650 __vma_link_file(vma);
651
652 if (mapping)
653 mutex_unlock(&mapping->i_mmap_mutex);
654
655 mm->map_count++;
656 validate_mm(mm);
657}
658
659/*
660 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
661 * mm's list and rbtree. It has already been inserted into the interval tree.
662 */
663static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
664{
665 struct vm_area_struct *prev;
666 struct rb_node **rb_link, *rb_parent;
667
668 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
669 &prev, &rb_link, &rb_parent))
670 BUG();
671 __vma_link(mm, vma, prev, rb_link, rb_parent);
672 mm->map_count++;
673}
674
675static inline void
676__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
677 struct vm_area_struct *prev)
678{
679 struct vm_area_struct *next;
680
681 vma_rb_erase(vma, &mm->mm_rb);
682 prev->vm_next = next = vma->vm_next;
683 if (next)
684 next->vm_prev = prev;
685
686 /* Kill the cache */
687 vmacache_invalidate(mm);
688}
689
690/*
691 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
692 * is already present in an i_mmap tree without adjusting the tree.
693 * The following helper function should be used when such adjustments
694 * are necessary. The "insert" vma (if any) is to be inserted
695 * before we drop the necessary locks.
696 */
697int vma_adjust(struct vm_area_struct *vma, unsigned long start,
698 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
699{
700 struct mm_struct *mm = vma->vm_mm;
701 struct vm_area_struct *next = vma->vm_next;
702 struct vm_area_struct *importer = NULL;
703 struct address_space *mapping = NULL;
704 struct rb_root *root = NULL;
705 struct anon_vma *anon_vma = NULL;
706 struct file *file = vma->vm_file;
707 bool start_changed = false, end_changed = false;
708 long adjust_next = 0;
709 int remove_next = 0;
710
711 if (next && !insert) {
712 struct vm_area_struct *exporter = NULL;
713
714 if (end >= next->vm_end) {
715 /*
716 * vma expands, overlapping all the next, and
717 * perhaps the one after too (mprotect case 6).
718 */
719again: remove_next = 1 + (end > next->vm_end);
720 end = next->vm_end;
721 exporter = next;
722 importer = vma;
723 } else if (end > next->vm_start) {
724 /*
725 * vma expands, overlapping part of the next:
726 * mprotect case 5 shifting the boundary up.
727 */
728 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
729 exporter = next;
730 importer = vma;
731 } else if (end < vma->vm_end) {
732 /*
733 * vma shrinks, and !insert tells it's not
734 * split_vma inserting another: so it must be
735 * mprotect case 4 shifting the boundary down.
736 */
737 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
738 exporter = vma;
739 importer = next;
740 }
741
742 /*
743 * Easily overlooked: when mprotect shifts the boundary,
744 * make sure the expanding vma has anon_vma set if the
745 * shrinking vma had, to cover any anon pages imported.
746 */
747 if (exporter && exporter->anon_vma && !importer->anon_vma) {
748 if (anon_vma_clone(importer, exporter))
749 return -ENOMEM;
750 importer->anon_vma = exporter->anon_vma;
751 }
752 }
753
754 if (file) {
755 mapping = file->f_mapping;
756 if (!(vma->vm_flags & VM_NONLINEAR)) {
757 root = &mapping->i_mmap;
758 uprobe_munmap(vma, vma->vm_start, vma->vm_end);
759
760 if (adjust_next)
761 uprobe_munmap(next, next->vm_start,
762 next->vm_end);
763 }
764
765 mutex_lock(&mapping->i_mmap_mutex);
766 if (insert) {
767 /*
768 * Put into interval tree now, so instantiated pages
769 * are visible to arm/parisc __flush_dcache_page
770 * throughout; but we cannot insert into address
771 * space until vma start or end is updated.
772 */
773 __vma_link_file(insert);
774 }
775 }
776
777 vma_adjust_trans_huge(vma, start, end, adjust_next);
778
779 anon_vma = vma->anon_vma;
780 if (!anon_vma && adjust_next)
781 anon_vma = next->anon_vma;
782 if (anon_vma) {
783 VM_BUG_ON(adjust_next && next->anon_vma &&
784 anon_vma != next->anon_vma);
785 anon_vma_lock_write(anon_vma);
786 anon_vma_interval_tree_pre_update_vma(vma);
787 if (adjust_next)
788 anon_vma_interval_tree_pre_update_vma(next);
789 }
790
791 if (root) {
792 flush_dcache_mmap_lock(mapping);
793 vma_interval_tree_remove(vma, root);
794 if (adjust_next)
795 vma_interval_tree_remove(next, root);
796 }
797
798 if (start != vma->vm_start) {
799 vma->vm_start = start;
800 start_changed = true;
801 }
802 if (end != vma->vm_end) {
803 vma->vm_end = end;
804 end_changed = true;
805 }
806 vma->vm_pgoff = pgoff;
807 if (adjust_next) {
808 next->vm_start += adjust_next << PAGE_SHIFT;
809 next->vm_pgoff += adjust_next;
810 }
811
812 if (root) {
813 if (adjust_next)
814 vma_interval_tree_insert(next, root);
815 vma_interval_tree_insert(vma, root);
816 flush_dcache_mmap_unlock(mapping);
817 }
818
819 if (remove_next) {
820 /*
821 * vma_merge has merged next into vma, and needs
822 * us to remove next before dropping the locks.
823 */
824 __vma_unlink(mm, next, vma);
825 if (file)
826 __remove_shared_vm_struct(next, file, mapping);
827 } else if (insert) {
828 /*
829 * split_vma has split insert from vma, and needs
830 * us to insert it before dropping the locks
831 * (it may either follow vma or precede it).
832 */
833 __insert_vm_struct(mm, insert);
834 } else {
835 if (start_changed)
836 vma_gap_update(vma);
837 if (end_changed) {
838 if (!next)
839 mm->highest_vm_end = end;
840 else if (!adjust_next)
841 vma_gap_update(next);
842 }
843 }
844
845 if (anon_vma) {
846 anon_vma_interval_tree_post_update_vma(vma);
847 if (adjust_next)
848 anon_vma_interval_tree_post_update_vma(next);
849 anon_vma_unlock_write(anon_vma);
850 }
851 if (mapping)
852 mutex_unlock(&mapping->i_mmap_mutex);
853
854 if (root) {
855 uprobe_mmap(vma);
856
857 if (adjust_next)
858 uprobe_mmap(next);
859 }
860
861 if (remove_next) {
862 if (file) {
863 uprobe_munmap(next, next->vm_start, next->vm_end);
864 fput(file);
865 }
866 if (next->anon_vma)
867 anon_vma_merge(vma, next);
868 mm->map_count--;
869 mpol_put(vma_policy(next));
870 kmem_cache_free(vm_area_cachep, next);
871 /*
872 * In mprotect's case 6 (see comments on vma_merge),
873 * we must remove another next too. It would clutter
874 * up the code too much to do both in one go.
875 */
876 next = vma->vm_next;
877 if (remove_next == 2)
878 goto again;
879 else if (next)
880 vma_gap_update(next);
881 else
882 mm->highest_vm_end = end;
883 }
884 if (insert && file)
885 uprobe_mmap(insert);
886
887 validate_mm(mm);
888
889 return 0;
890}
891
892/*
893 * If the vma has a ->close operation then the driver probably needs to release
894 * per-vma resources, so we don't attempt to merge those.
895 */
896static inline int is_mergeable_vma(struct vm_area_struct *vma,
897 struct file *file, unsigned long vm_flags)
898{
899 /*
900 * VM_SOFTDIRTY should not prevent from VMA merging, if we
901 * match the flags but dirty bit -- the caller should mark
902 * merged VMA as dirty. If dirty bit won't be excluded from
903 * comparison, we increase pressue on the memory system forcing
904 * the kernel to generate new VMAs when old one could be
905 * extended instead.
906 */
907 if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
908 return 0;
909 if (vma->vm_file != file)
910 return 0;
911 if (vma->vm_ops && vma->vm_ops->close)
912 return 0;
913 return 1;
914}
915
916static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
917 struct anon_vma *anon_vma2,
918 struct vm_area_struct *vma)
919{
920 /*
921 * The list_is_singular() test is to avoid merging VMA cloned from
922 * parents. This can improve scalability caused by anon_vma lock.
923 */
924 if ((!anon_vma1 || !anon_vma2) && (!vma ||
925 list_is_singular(&vma->anon_vma_chain)))
926 return 1;
927 return anon_vma1 == anon_vma2;
928}
929
930/*
931 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
932 * in front of (at a lower virtual address and file offset than) the vma.
933 *
934 * We cannot merge two vmas if they have differently assigned (non-NULL)
935 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
936 *
937 * We don't check here for the merged mmap wrapping around the end of pagecache
938 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
939 * wrap, nor mmaps which cover the final page at index -1UL.
940 */
941static int
942can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
943 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
944{
945 if (is_mergeable_vma(vma, file, vm_flags) &&
946 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
947 if (vma->vm_pgoff == vm_pgoff)
948 return 1;
949 }
950 return 0;
951}
952
953/*
954 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
955 * beyond (at a higher virtual address and file offset than) the vma.
956 *
957 * We cannot merge two vmas if they have differently assigned (non-NULL)
958 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
959 */
960static int
961can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
962 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
963{
964 if (is_mergeable_vma(vma, file, vm_flags) &&
965 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
966 pgoff_t vm_pglen;
967 vm_pglen = vma_pages(vma);
968 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
969 return 1;
970 }
971 return 0;
972}
973
974/*
975 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
976 * whether that can be merged with its predecessor or its successor.
977 * Or both (it neatly fills a hole).
978 *
979 * In most cases - when called for mmap, brk or mremap - [addr,end) is
980 * certain not to be mapped by the time vma_merge is called; but when
981 * called for mprotect, it is certain to be already mapped (either at
982 * an offset within prev, or at the start of next), and the flags of
983 * this area are about to be changed to vm_flags - and the no-change
984 * case has already been eliminated.
985 *
986 * The following mprotect cases have to be considered, where AAAA is
987 * the area passed down from mprotect_fixup, never extending beyond one
988 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
989 *
990 * AAAA AAAA AAAA AAAA
991 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
992 * cannot merge might become might become might become
993 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
994 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
995 * mremap move: PPPPNNNNNNNN 8
996 * AAAA
997 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
998 * might become case 1 below case 2 below case 3 below
999 *
1000 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
1001 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
1002 */
1003struct vm_area_struct *vma_merge(struct mm_struct *mm,
1004 struct vm_area_struct *prev, unsigned long addr,
1005 unsigned long end, unsigned long vm_flags,
1006 struct anon_vma *anon_vma, struct file *file,
1007 pgoff_t pgoff, struct mempolicy *policy)
1008{
1009 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
1010 struct vm_area_struct *area, *next;
1011 int err;
1012
1013 /*
1014 * We later require that vma->vm_flags == vm_flags,
1015 * so this tests vma->vm_flags & VM_SPECIAL, too.
1016 */
1017 if (vm_flags & VM_SPECIAL)
1018 return NULL;
1019
1020 if (prev)
1021 next = prev->vm_next;
1022 else
1023 next = mm->mmap;
1024 area = next;
1025 if (next && next->vm_end == end) /* cases 6, 7, 8 */
1026 next = next->vm_next;
1027
1028 /*
1029 * Can it merge with the predecessor?
1030 */
1031 if (prev && prev->vm_end == addr &&
1032 mpol_equal(vma_policy(prev), policy) &&
1033 can_vma_merge_after(prev, vm_flags,
1034 anon_vma, file, pgoff)) {
1035 /*
1036 * OK, it can. Can we now merge in the successor as well?
1037 */
1038 if (next && end == next->vm_start &&
1039 mpol_equal(policy, vma_policy(next)) &&
1040 can_vma_merge_before(next, vm_flags,
1041 anon_vma, file, pgoff+pglen) &&
1042 is_mergeable_anon_vma(prev->anon_vma,
1043 next->anon_vma, NULL)) {
1044 /* cases 1, 6 */
1045 err = vma_adjust(prev, prev->vm_start,
1046 next->vm_end, prev->vm_pgoff, NULL);
1047 } else /* cases 2, 5, 7 */
1048 err = vma_adjust(prev, prev->vm_start,
1049 end, prev->vm_pgoff, NULL);
1050 if (err)
1051 return NULL;
1052 khugepaged_enter_vma_merge(prev);
1053 return prev;
1054 }
1055
1056 /*
1057 * Can this new request be merged in front of next?
1058 */
1059 if (next && end == next->vm_start &&
1060 mpol_equal(policy, vma_policy(next)) &&
1061 can_vma_merge_before(next, vm_flags,
1062 anon_vma, file, pgoff+pglen)) {
1063 if (prev && addr < prev->vm_end) /* case 4 */
1064 err = vma_adjust(prev, prev->vm_start,
1065 addr, prev->vm_pgoff, NULL);
1066 else /* cases 3, 8 */
1067 err = vma_adjust(area, addr, next->vm_end,
1068 next->vm_pgoff - pglen, NULL);
1069 if (err)
1070 return NULL;
1071 khugepaged_enter_vma_merge(area);
1072 return area;
1073 }
1074
1075 return NULL;
1076}
1077
1078/*
1079 * Rough compatbility check to quickly see if it's even worth looking
1080 * at sharing an anon_vma.
1081 *
1082 * They need to have the same vm_file, and the flags can only differ
1083 * in things that mprotect may change.
1084 *
1085 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1086 * we can merge the two vma's. For example, we refuse to merge a vma if
1087 * there is a vm_ops->close() function, because that indicates that the
1088 * driver is doing some kind of reference counting. But that doesn't
1089 * really matter for the anon_vma sharing case.
1090 */
1091static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1092{
1093 return a->vm_end == b->vm_start &&
1094 mpol_equal(vma_policy(a), vma_policy(b)) &&
1095 a->vm_file == b->vm_file &&
1096 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) &&
1097 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1098}
1099
1100/*
1101 * Do some basic sanity checking to see if we can re-use the anon_vma
1102 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1103 * the same as 'old', the other will be the new one that is trying
1104 * to share the anon_vma.
1105 *
1106 * NOTE! This runs with mm_sem held for reading, so it is possible that
1107 * the anon_vma of 'old' is concurrently in the process of being set up
1108 * by another page fault trying to merge _that_. But that's ok: if it
1109 * is being set up, that automatically means that it will be a singleton
1110 * acceptable for merging, so we can do all of this optimistically. But
1111 * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
1112 *
1113 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1114 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1115 * is to return an anon_vma that is "complex" due to having gone through
1116 * a fork).
1117 *
1118 * We also make sure that the two vma's are compatible (adjacent,
1119 * and with the same memory policies). That's all stable, even with just
1120 * a read lock on the mm_sem.
1121 */
1122static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1123{
1124 if (anon_vma_compatible(a, b)) {
1125 struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma);
1126
1127 if (anon_vma && list_is_singular(&old->anon_vma_chain))
1128 return anon_vma;
1129 }
1130 return NULL;
1131}
1132
1133/*
1134 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1135 * neighbouring vmas for a suitable anon_vma, before it goes off
1136 * to allocate a new anon_vma. It checks because a repetitive
1137 * sequence of mprotects and faults may otherwise lead to distinct
1138 * anon_vmas being allocated, preventing vma merge in subsequent
1139 * mprotect.
1140 */
1141struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1142{
1143 struct anon_vma *anon_vma;
1144 struct vm_area_struct *near;
1145
1146 near = vma->vm_next;
1147 if (!near)
1148 goto try_prev;
1149
1150 anon_vma = reusable_anon_vma(near, vma, near);
1151 if (anon_vma)
1152 return anon_vma;
1153try_prev:
1154 near = vma->vm_prev;
1155 if (!near)
1156 goto none;
1157
1158 anon_vma = reusable_anon_vma(near, near, vma);
1159 if (anon_vma)
1160 return anon_vma;
1161none:
1162 /*
1163 * There's no absolute need to look only at touching neighbours:
1164 * we could search further afield for "compatible" anon_vmas.
1165 * But it would probably just be a waste of time searching,
1166 * or lead to too many vmas hanging off the same anon_vma.
1167 * We're trying to allow mprotect remerging later on,
1168 * not trying to minimize memory used for anon_vmas.
1169 */
1170 return NULL;
1171}
1172
1173#ifdef CONFIG_PROC_FS
1174void vm_stat_account(struct mm_struct *mm, unsigned long flags,
1175 struct file *file, long pages)
1176{
1177 const unsigned long stack_flags
1178 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
1179
1180 mm->total_vm += pages;
1181
1182 if (file) {
1183 mm->shared_vm += pages;
1184 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
1185 mm->exec_vm += pages;
1186 } else if (flags & stack_flags)
1187 mm->stack_vm += pages;
1188}
1189#endif /* CONFIG_PROC_FS */
1190
1191/*
1192 * If a hint addr is less than mmap_min_addr change hint to be as
1193 * low as possible but still greater than mmap_min_addr
1194 */
1195static inline unsigned long round_hint_to_min(unsigned long hint)
1196{
1197 hint &= PAGE_MASK;
1198 if (((void *)hint != NULL) &&
1199 (hint < mmap_min_addr))
1200 return PAGE_ALIGN(mmap_min_addr);
1201 return hint;
1202}
1203
1204static inline int mlock_future_check(struct mm_struct *mm,
1205 unsigned long flags,
1206 unsigned long len)
1207{
1208 unsigned long locked, lock_limit;
1209
1210 /* mlock MCL_FUTURE? */
1211 if (flags & VM_LOCKED) {
1212 locked = len >> PAGE_SHIFT;
1213 locked += mm->locked_vm;
1214 lock_limit = rlimit(RLIMIT_MEMLOCK);
1215 lock_limit >>= PAGE_SHIFT;
1216 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1217 return -EAGAIN;
1218 }
1219 return 0;
1220}
1221
1222/*
1223 * The caller must hold down_write(¤t->mm->mmap_sem).
1224 */
1225
1226unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
1227 unsigned long len, unsigned long prot,
1228 unsigned long flags, unsigned long pgoff,
1229 unsigned long *populate)
1230{
1231 struct mm_struct * mm = current->mm;
1232 vm_flags_t vm_flags;
1233
1234 *populate = 0;
1235
1236 /*
1237 * Does the application expect PROT_READ to imply PROT_EXEC?
1238 *
1239 * (the exception is when the underlying filesystem is noexec
1240 * mounted, in which case we dont add PROT_EXEC.)
1241 */
1242 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1243 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
1244 prot |= PROT_EXEC;
1245
1246 if (!len)
1247 return -EINVAL;
1248
1249 if (!(flags & MAP_FIXED))
1250 addr = round_hint_to_min(addr);
1251
1252 /* Careful about overflows.. */
1253 len = PAGE_ALIGN(len);
1254 if (!len)
1255 return -ENOMEM;
1256
1257 /* offset overflow? */
1258 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1259 return -EOVERFLOW;
1260
1261 /* Too many mappings? */
1262 if (mm->map_count > sysctl_max_map_count)
1263 return -ENOMEM;
1264
1265 /* Obtain the address to map to. we verify (or select) it and ensure
1266 * that it represents a valid section of the address space.
1267 */
1268 addr = get_unmapped_area(file, addr, len, pgoff, flags);
1269 if (addr & ~PAGE_MASK)
1270 return addr;
1271
1272 /* Do simple checking here so the lower-level routines won't have
1273 * to. we assume access permissions have been handled by the open
1274 * of the memory object, so we don't do any here.
1275 */
1276 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
1277 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1278
1279 if (flags & MAP_LOCKED)
1280 if (!can_do_mlock())
1281 return -EPERM;
1282
1283 if (mlock_future_check(mm, vm_flags, len))
1284 return -EAGAIN;
1285
1286 if (file) {
1287 struct inode *inode = file_inode(file);
1288
1289 switch (flags & MAP_TYPE) {
1290 case MAP_SHARED:
1291 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1292 return -EACCES;
1293
1294 /*
1295 * Make sure we don't allow writing to an append-only
1296 * file..
1297 */
1298 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1299 return -EACCES;
1300
1301 /*
1302 * Make sure there are no mandatory locks on the file.
1303 */
1304 if (locks_verify_locked(file))
1305 return -EAGAIN;
1306
1307 vm_flags |= VM_SHARED | VM_MAYSHARE;
1308 if (!(file->f_mode & FMODE_WRITE))
1309 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1310
1311 /* fall through */
1312 case MAP_PRIVATE:
1313 if (!(file->f_mode & FMODE_READ))
1314 return -EACCES;
1315 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1316 if (vm_flags & VM_EXEC)
1317 return -EPERM;
1318 vm_flags &= ~VM_MAYEXEC;
1319 }
1320
1321 if (!file->f_op->mmap)
1322 return -ENODEV;
1323 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1324 return -EINVAL;
1325 break;
1326
1327 default:
1328 return -EINVAL;
1329 }
1330 } else {
1331 switch (flags & MAP_TYPE) {
1332 case MAP_SHARED:
1333 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1334 return -EINVAL;
1335 /*
1336 * Ignore pgoff.
1337 */
1338 pgoff = 0;
1339 vm_flags |= VM_SHARED | VM_MAYSHARE;
1340 break;
1341 case MAP_PRIVATE:
1342 /*
1343 * Set pgoff according to addr for anon_vma.
1344 */
1345 pgoff = addr >> PAGE_SHIFT;
1346 break;
1347 default:
1348 return -EINVAL;
1349 }
1350 }
1351
1352 /*
1353 * Set 'VM_NORESERVE' if we should not account for the
1354 * memory use of this mapping.
1355 */
1356 if (flags & MAP_NORESERVE) {
1357 /* We honor MAP_NORESERVE if allowed to overcommit */
1358 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1359 vm_flags |= VM_NORESERVE;
1360
1361 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1362 if (file && is_file_hugepages(file))
1363 vm_flags |= VM_NORESERVE;
1364 }
1365
1366 addr = mmap_region(file, addr, len, vm_flags, pgoff);
1367 if (!IS_ERR_VALUE(addr) &&
1368 ((vm_flags & VM_LOCKED) ||
1369 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1370 *populate = len;
1371 return addr;
1372}
1373
1374SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1375 unsigned long, prot, unsigned long, flags,
1376 unsigned long, fd, unsigned long, pgoff)
1377{
1378 struct file *file = NULL;
1379 unsigned long retval = -EBADF;
1380
1381 if (!(flags & MAP_ANONYMOUS)) {
1382 audit_mmap_fd(fd, flags);
1383 file = fget(fd);
1384 if (!file)
1385 goto out;
1386 if (is_file_hugepages(file))
1387 len = ALIGN(len, huge_page_size(hstate_file(file)));
1388 retval = -EINVAL;
1389 if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
1390 goto out_fput;
1391 } else if (flags & MAP_HUGETLB) {
1392 struct user_struct *user = NULL;
1393 struct hstate *hs;
1394
1395 hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK);
1396 if (!hs)
1397 return -EINVAL;
1398
1399 len = ALIGN(len, huge_page_size(hs));
1400 /*
1401 * VM_NORESERVE is used because the reservations will be
1402 * taken when vm_ops->mmap() is called
1403 * A dummy user value is used because we are not locking
1404 * memory so no accounting is necessary
1405 */
1406 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1407 VM_NORESERVE,
1408 &user, HUGETLB_ANONHUGE_INODE,
1409 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1410 if (IS_ERR(file))
1411 return PTR_ERR(file);
1412 }
1413
1414 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1415
1416 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1417out_fput:
1418 if (file)
1419 fput(file);
1420out:
1421 return retval;
1422}
1423
1424#ifdef __ARCH_WANT_SYS_OLD_MMAP
1425struct mmap_arg_struct {
1426 unsigned long addr;
1427 unsigned long len;
1428 unsigned long prot;
1429 unsigned long flags;
1430 unsigned long fd;
1431 unsigned long offset;
1432};
1433
1434SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1435{
1436 struct mmap_arg_struct a;
1437
1438 if (copy_from_user(&a, arg, sizeof(a)))
1439 return -EFAULT;
1440 if (a.offset & ~PAGE_MASK)
1441 return -EINVAL;
1442
1443 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1444 a.offset >> PAGE_SHIFT);
1445}
1446#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1447
1448/*
1449 * Some shared mappigns will want the pages marked read-only
1450 * to track write events. If so, we'll downgrade vm_page_prot
1451 * to the private version (using protection_map[] without the
1452 * VM_SHARED bit).
1453 */
1454int vma_wants_writenotify(struct vm_area_struct *vma)
1455{
1456 vm_flags_t vm_flags = vma->vm_flags;
1457
1458 /* If it was private or non-writable, the write bit is already clear */
1459 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1460 return 0;
1461
1462 /* The backer wishes to know when pages are first written to? */
1463 if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1464 return 1;
1465
1466 /* The open routine did something to the protections already? */
1467 if (pgprot_val(vma->vm_page_prot) !=
1468 pgprot_val(vm_get_page_prot(vm_flags)))
1469 return 0;
1470
1471 /* Specialty mapping? */
1472 if (vm_flags & VM_PFNMAP)
1473 return 0;
1474
1475 /* Can the mapping track the dirty pages? */
1476 return vma->vm_file && vma->vm_file->f_mapping &&
1477 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1478}
1479
1480/*
1481 * We account for memory if it's a private writeable mapping,
1482 * not hugepages and VM_NORESERVE wasn't set.
1483 */
1484static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1485{
1486 /*
1487 * hugetlb has its own accounting separate from the core VM
1488 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1489 */
1490 if (file && is_file_hugepages(file))
1491 return 0;
1492
1493 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1494}
1495
1496unsigned long mmap_region(struct file *file, unsigned long addr,
1497 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
1498{
1499 struct mm_struct *mm = current->mm;
1500 struct vm_area_struct *vma, *prev;
1501 int error;
1502 struct rb_node **rb_link, *rb_parent;
1503 unsigned long charged = 0;
1504
1505 /* Check against address space limit. */
1506 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) {
1507 unsigned long nr_pages;
1508
1509 /*
1510 * MAP_FIXED may remove pages of mappings that intersects with
1511 * requested mapping. Account for the pages it would unmap.
1512 */
1513 if (!(vm_flags & MAP_FIXED))
1514 return -ENOMEM;
1515
1516 nr_pages = count_vma_pages_range(mm, addr, addr + len);
1517
1518 if (!may_expand_vm(mm, (len >> PAGE_SHIFT) - nr_pages))
1519 return -ENOMEM;
1520 }
1521
1522 /* Clear old maps */
1523 error = -ENOMEM;
1524munmap_back:
1525 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
1526 if (do_munmap(mm, addr, len))
1527 return -ENOMEM;
1528 goto munmap_back;
1529 }
1530
1531 /*
1532 * Private writable mapping: check memory availability
1533 */
1534 if (accountable_mapping(file, vm_flags)) {
1535 charged = len >> PAGE_SHIFT;
1536 if (security_vm_enough_memory_mm(mm, charged))
1537 return -ENOMEM;
1538 vm_flags |= VM_ACCOUNT;
1539 }
1540
1541 /*
1542 * Can we just expand an old mapping?
1543 */
1544 vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
1545 if (vma)
1546 goto out;
1547
1548 /*
1549 * Determine the object being mapped and call the appropriate
1550 * specific mapper. the address has already been validated, but
1551 * not unmapped, but the maps are removed from the list.
1552 */
1553 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1554 if (!vma) {
1555 error = -ENOMEM;
1556 goto unacct_error;
1557 }
1558
1559 vma->vm_mm = mm;
1560 vma->vm_start = addr;
1561 vma->vm_end = addr + len;
1562 vma->vm_flags = vm_flags;
1563 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1564 vma->vm_pgoff = pgoff;
1565 INIT_LIST_HEAD(&vma->anon_vma_chain);
1566
1567 if (file) {
1568 if (vm_flags & VM_DENYWRITE) {
1569 error = deny_write_access(file);
1570 if (error)
1571 goto free_vma;
1572 }
1573 vma->vm_file = get_file(file);
1574 error = file->f_op->mmap(file, vma);
1575 if (error)
1576 goto unmap_and_free_vma;
1577
1578 /* Can addr have changed??
1579 *
1580 * Answer: Yes, several device drivers can do it in their
1581 * f_op->mmap method. -DaveM
1582 * Bug: If addr is changed, prev, rb_link, rb_parent should
1583 * be updated for vma_link()
1584 */
1585 WARN_ON_ONCE(addr != vma->vm_start);
1586
1587 addr = vma->vm_start;
1588 vm_flags = vma->vm_flags;
1589 } else if (vm_flags & VM_SHARED) {
1590 error = shmem_zero_setup(vma);
1591 if (error)
1592 goto free_vma;
1593 }
1594
1595 if (vma_wants_writenotify(vma)) {
1596 pgprot_t pprot = vma->vm_page_prot;
1597
1598 /* Can vma->vm_page_prot have changed??
1599 *
1600 * Answer: Yes, drivers may have changed it in their
1601 * f_op->mmap method.
1602 *
1603 * Ensures that vmas marked as uncached stay that way.
1604 */
1605 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1606 if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
1607 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
1608 }
1609
1610 vma_link(mm, vma, prev, rb_link, rb_parent);
1611 /* Once vma denies write, undo our temporary denial count */
1612 if (vm_flags & VM_DENYWRITE)
1613 allow_write_access(file);
1614 file = vma->vm_file;
1615out:
1616 perf_event_mmap(vma);
1617
1618 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1619 if (vm_flags & VM_LOCKED) {
1620 if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
1621 vma == get_gate_vma(current->mm)))
1622 mm->locked_vm += (len >> PAGE_SHIFT);
1623 else
1624 vma->vm_flags &= ~VM_LOCKED;
1625 }
1626
1627 if (file)
1628 uprobe_mmap(vma);
1629
1630 /*
1631 * New (or expanded) vma always get soft dirty status.
1632 * Otherwise user-space soft-dirty page tracker won't
1633 * be able to distinguish situation when vma area unmapped,
1634 * then new mapped in-place (which must be aimed as
1635 * a completely new data area).
1636 */
1637 vma->vm_flags |= VM_SOFTDIRTY;
1638
1639 return addr;
1640
1641unmap_and_free_vma:
1642 if (vm_flags & VM_DENYWRITE)
1643 allow_write_access(file);
1644 vma->vm_file = NULL;
1645 fput(file);
1646
1647 /* Undo any partial mapping done by a device driver. */
1648 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1649 charged = 0;
1650free_vma:
1651 kmem_cache_free(vm_area_cachep, vma);
1652unacct_error:
1653 if (charged)
1654 vm_unacct_memory(charged);
1655 return error;
1656}
1657
1658unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1659{
1660 /*
1661 * We implement the search by looking for an rbtree node that
1662 * immediately follows a suitable gap. That is,
1663 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1664 * - gap_end = vma->vm_start >= info->low_limit + length;
1665 * - gap_end - gap_start >= length
1666 */
1667
1668 struct mm_struct *mm = current->mm;
1669 struct vm_area_struct *vma;
1670 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1671
1672 /* Adjust search length to account for worst case alignment overhead */
1673 length = info->length + info->align_mask;
1674 if (length < info->length)
1675 return -ENOMEM;
1676
1677 /* Adjust search limits by the desired length */
1678 if (info->high_limit < length)
1679 return -ENOMEM;
1680 high_limit = info->high_limit - length;
1681
1682 if (info->low_limit > high_limit)
1683 return -ENOMEM;
1684 low_limit = info->low_limit + length;
1685
1686 /* Check if rbtree root looks promising */
1687 if (RB_EMPTY_ROOT(&mm->mm_rb))
1688 goto check_highest;
1689 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1690 if (vma->rb_subtree_gap < length)
1691 goto check_highest;
1692
1693 while (true) {
1694 /* Visit left subtree if it looks promising */
1695 gap_end = vma->vm_start;
1696 if (gap_end >= low_limit && vma->vm_rb.rb_left) {
1697 struct vm_area_struct *left =
1698 rb_entry(vma->vm_rb.rb_left,
1699 struct vm_area_struct, vm_rb);
1700 if (left->rb_subtree_gap >= length) {
1701 vma = left;
1702 continue;
1703 }
1704 }
1705
1706 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1707check_current:
1708 /* Check if current node has a suitable gap */
1709 if (gap_start > high_limit)
1710 return -ENOMEM;
1711 if (gap_end >= low_limit && gap_end - gap_start >= length)
1712 goto found;
1713
1714 /* Visit right subtree if it looks promising */
1715 if (vma->vm_rb.rb_right) {
1716 struct vm_area_struct *right =
1717 rb_entry(vma->vm_rb.rb_right,
1718 struct vm_area_struct, vm_rb);
1719 if (right->rb_subtree_gap >= length) {
1720 vma = right;
1721 continue;
1722 }
1723 }
1724
1725 /* Go back up the rbtree to find next candidate node */
1726 while (true) {
1727 struct rb_node *prev = &vma->vm_rb;
1728 if (!rb_parent(prev))
1729 goto check_highest;
1730 vma = rb_entry(rb_parent(prev),
1731 struct vm_area_struct, vm_rb);
1732 if (prev == vma->vm_rb.rb_left) {
1733 gap_start = vma->vm_prev->vm_end;
1734 gap_end = vma->vm_start;
1735 goto check_current;
1736 }
1737 }
1738 }
1739
1740check_highest:
1741 /* Check highest gap, which does not precede any rbtree node */
1742 gap_start = mm->highest_vm_end;
1743 gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */
1744 if (gap_start > high_limit)
1745 return -ENOMEM;
1746
1747found:
1748 /* We found a suitable gap. Clip it with the original low_limit. */
1749 if (gap_start < info->low_limit)
1750 gap_start = info->low_limit;
1751
1752 /* Adjust gap address to the desired alignment */
1753 gap_start += (info->align_offset - gap_start) & info->align_mask;
1754
1755 VM_BUG_ON(gap_start + info->length > info->high_limit);
1756 VM_BUG_ON(gap_start + info->length > gap_end);
1757 return gap_start;
1758}
1759
1760unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
1761{
1762 struct mm_struct *mm = current->mm;
1763 struct vm_area_struct *vma;
1764 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1765
1766 /* Adjust search length to account for worst case alignment overhead */
1767 length = info->length + info->align_mask;
1768 if (length < info->length)
1769 return -ENOMEM;
1770
1771 /*
1772 * Adjust search limits by the desired length.
1773 * See implementation comment at top of unmapped_area().
1774 */
1775 gap_end = info->high_limit;
1776 if (gap_end < length)
1777 return -ENOMEM;
1778 high_limit = gap_end - length;
1779
1780 if (info->low_limit > high_limit)
1781 return -ENOMEM;
1782 low_limit = info->low_limit + length;
1783
1784 /* Check highest gap, which does not precede any rbtree node */
1785 gap_start = mm->highest_vm_end;
1786 if (gap_start <= high_limit)
1787 goto found_highest;
1788
1789 /* Check if rbtree root looks promising */
1790 if (RB_EMPTY_ROOT(&mm->mm_rb))
1791 return -ENOMEM;
1792 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1793 if (vma->rb_subtree_gap < length)
1794 return -ENOMEM;
1795
1796 while (true) {
1797 /* Visit right subtree if it looks promising */
1798 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1799 if (gap_start <= high_limit && vma->vm_rb.rb_right) {
1800 struct vm_area_struct *right =
1801 rb_entry(vma->vm_rb.rb_right,
1802 struct vm_area_struct, vm_rb);
1803 if (right->rb_subtree_gap >= length) {
1804 vma = right;
1805 continue;
1806 }
1807 }
1808
1809check_current:
1810 /* Check if current node has a suitable gap */
1811 gap_end = vma->vm_start;
1812 if (gap_end < low_limit)
1813 return -ENOMEM;
1814 if (gap_start <= high_limit && gap_end - gap_start >= length)
1815 goto found;
1816
1817 /* Visit left subtree if it looks promising */
1818 if (vma->vm_rb.rb_left) {
1819 struct vm_area_struct *left =
1820 rb_entry(vma->vm_rb.rb_left,
1821 struct vm_area_struct, vm_rb);
1822 if (left->rb_subtree_gap >= length) {
1823 vma = left;
1824 continue;
1825 }
1826 }
1827
1828 /* Go back up the rbtree to find next candidate node */
1829 while (true) {
1830 struct rb_node *prev = &vma->vm_rb;
1831 if (!rb_parent(prev))
1832 return -ENOMEM;
1833 vma = rb_entry(rb_parent(prev),
1834 struct vm_area_struct, vm_rb);
1835 if (prev == vma->vm_rb.rb_right) {
1836 gap_start = vma->vm_prev ?
1837 vma->vm_prev->vm_end : 0;
1838 goto check_current;
1839 }
1840 }
1841 }
1842
1843found:
1844 /* We found a suitable gap. Clip it with the original high_limit. */
1845 if (gap_end > info->high_limit)
1846 gap_end = info->high_limit;
1847
1848found_highest:
1849 /* Compute highest gap address at the desired alignment */
1850 gap_end -= info->length;
1851 gap_end -= (gap_end - info->align_offset) & info->align_mask;
1852
1853 VM_BUG_ON(gap_end < info->low_limit);
1854 VM_BUG_ON(gap_end < gap_start);
1855 return gap_end;
1856}
1857
1858/* Get an address range which is currently unmapped.
1859 * For shmat() with addr=0.
1860 *
1861 * Ugly calling convention alert:
1862 * Return value with the low bits set means error value,
1863 * ie
1864 * if (ret & ~PAGE_MASK)
1865 * error = ret;
1866 *
1867 * This function "knows" that -ENOMEM has the bits set.
1868 */
1869#ifndef HAVE_ARCH_UNMAPPED_AREA
1870unsigned long
1871arch_get_unmapped_area(struct file *filp, unsigned long addr,
1872 unsigned long len, unsigned long pgoff, unsigned long flags)
1873{
1874 struct mm_struct *mm = current->mm;
1875 struct vm_area_struct *vma;
1876 struct vm_unmapped_area_info info;
1877
1878 if (len > TASK_SIZE - mmap_min_addr)
1879 return -ENOMEM;
1880
1881 if (flags & MAP_FIXED)
1882 return addr;
1883
1884 if (addr) {
1885 addr = PAGE_ALIGN(addr);
1886 vma = find_vma(mm, addr);
1887 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
1888 (!vma || addr + len <= vma->vm_start))
1889 return addr;
1890 }
1891
1892 info.flags = 0;
1893 info.length = len;
1894 info.low_limit = mm->mmap_base;
1895 info.high_limit = TASK_SIZE;
1896 info.align_mask = 0;
1897 return vm_unmapped_area(&info);
1898}
1899#endif
1900
1901/*
1902 * This mmap-allocator allocates new areas top-down from below the
1903 * stack's low limit (the base):
1904 */
1905#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1906unsigned long
1907arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1908 const unsigned long len, const unsigned long pgoff,
1909 const unsigned long flags)
1910{
1911 struct vm_area_struct *vma;
1912 struct mm_struct *mm = current->mm;
1913 unsigned long addr = addr0;
1914 struct vm_unmapped_area_info info;
1915
1916 /* requested length too big for entire address space */
1917 if (len > TASK_SIZE - mmap_min_addr)
1918 return -ENOMEM;
1919
1920 if (flags & MAP_FIXED)
1921 return addr;
1922
1923 /* requesting a specific address */
1924 if (addr) {
1925 addr = PAGE_ALIGN(addr);
1926 vma = find_vma(mm, addr);
1927 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
1928 (!vma || addr + len <= vma->vm_start))
1929 return addr;
1930 }
1931
1932 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
1933 info.length = len;
1934 info.low_limit = max(PAGE_SIZE, mmap_min_addr);
1935 info.high_limit = mm->mmap_base;
1936 info.align_mask = 0;
1937 addr = vm_unmapped_area(&info);
1938
1939 /*
1940 * A failed mmap() very likely causes application failure,
1941 * so fall back to the bottom-up function here. This scenario
1942 * can happen with large stack limits and large mmap()
1943 * allocations.
1944 */
1945 if (addr & ~PAGE_MASK) {
1946 VM_BUG_ON(addr != -ENOMEM);
1947 info.flags = 0;
1948 info.low_limit = TASK_UNMAPPED_BASE;
1949 info.high_limit = TASK_SIZE;
1950 addr = vm_unmapped_area(&info);
1951 }
1952
1953 return addr;
1954}
1955#endif
1956
1957unsigned long
1958get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1959 unsigned long pgoff, unsigned long flags)
1960{
1961 unsigned long (*get_area)(struct file *, unsigned long,
1962 unsigned long, unsigned long, unsigned long);
1963
1964 unsigned long error = arch_mmap_check(addr, len, flags);
1965 if (error)
1966 return error;
1967
1968 /* Careful about overflows.. */
1969 if (len > TASK_SIZE)
1970 return -ENOMEM;
1971
1972 get_area = current->mm->get_unmapped_area;
1973 if (file && file->f_op->get_unmapped_area)
1974 get_area = file->f_op->get_unmapped_area;
1975 addr = get_area(file, addr, len, pgoff, flags);
1976 if (IS_ERR_VALUE(addr))
1977 return addr;
1978
1979 if (addr > TASK_SIZE - len)
1980 return -ENOMEM;
1981 if (addr & ~PAGE_MASK)
1982 return -EINVAL;
1983
1984 addr = arch_rebalance_pgtables(addr, len);
1985 error = security_mmap_addr(addr);
1986 return error ? error : addr;
1987}
1988
1989EXPORT_SYMBOL(get_unmapped_area);
1990
1991/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1992struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1993{
1994 struct rb_node *rb_node;
1995 struct vm_area_struct *vma;
1996
1997 /* Check the cache first. */
1998 vma = vmacache_find(mm, addr);
1999 if (likely(vma))
2000 return vma;
2001
2002 rb_node = mm->mm_rb.rb_node;
2003 vma = NULL;
2004
2005 while (rb_node) {
2006 struct vm_area_struct *tmp;
2007
2008 tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2009
2010 if (tmp->vm_end > addr) {
2011 vma = tmp;
2012 if (tmp->vm_start <= addr)
2013 break;
2014 rb_node = rb_node->rb_left;
2015 } else
2016 rb_node = rb_node->rb_right;
2017 }
2018
2019 if (vma)
2020 vmacache_update(addr, vma);
2021 return vma;
2022}
2023
2024EXPORT_SYMBOL(find_vma);
2025
2026/*
2027 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
2028 */
2029struct vm_area_struct *
2030find_vma_prev(struct mm_struct *mm, unsigned long addr,
2031 struct vm_area_struct **pprev)
2032{
2033 struct vm_area_struct *vma;
2034
2035 vma = find_vma(mm, addr);
2036 if (vma) {
2037 *pprev = vma->vm_prev;
2038 } else {
2039 struct rb_node *rb_node = mm->mm_rb.rb_node;
2040 *pprev = NULL;
2041 while (rb_node) {
2042 *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2043 rb_node = rb_node->rb_right;
2044 }
2045 }
2046 return vma;
2047}
2048
2049/*
2050 * Verify that the stack growth is acceptable and
2051 * update accounting. This is shared with both the
2052 * grow-up and grow-down cases.
2053 */
2054static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
2055{
2056 struct mm_struct *mm = vma->vm_mm;
2057 struct rlimit *rlim = current->signal->rlim;
2058 unsigned long new_start;
2059
2060 /* address space limit tests */
2061 if (!may_expand_vm(mm, grow))
2062 return -ENOMEM;
2063
2064 /* Stack limit test */
2065 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
2066 return -ENOMEM;
2067
2068 /* mlock limit tests */
2069 if (vma->vm_flags & VM_LOCKED) {
2070 unsigned long locked;
2071 unsigned long limit;
2072 locked = mm->locked_vm + grow;
2073 limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
2074 limit >>= PAGE_SHIFT;
2075 if (locked > limit && !capable(CAP_IPC_LOCK))
2076 return -ENOMEM;
2077 }
2078
2079 /* Check to ensure the stack will not grow into a hugetlb-only region */
2080 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
2081 vma->vm_end - size;
2082 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
2083 return -EFAULT;
2084
2085 /*
2086 * Overcommit.. This must be the final test, as it will
2087 * update security statistics.
2088 */
2089 if (security_vm_enough_memory_mm(mm, grow))
2090 return -ENOMEM;
2091
2092 /* Ok, everything looks good - let it rip */
2093 if (vma->vm_flags & VM_LOCKED)
2094 mm->locked_vm += grow;
2095 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
2096 return 0;
2097}
2098
2099#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2100/*
2101 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2102 * vma is the last one with address > vma->vm_end. Have to extend vma.
2103 */
2104int expand_upwards(struct vm_area_struct *vma, unsigned long address)
2105{
2106 int error;
2107
2108 if (!(vma->vm_flags & VM_GROWSUP))
2109 return -EFAULT;
2110
2111 /*
2112 * We must make sure the anon_vma is allocated
2113 * so that the anon_vma locking is not a noop.
2114 */
2115 if (unlikely(anon_vma_prepare(vma)))
2116 return -ENOMEM;
2117 vma_lock_anon_vma(vma);
2118
2119 /*
2120 * vma->vm_start/vm_end cannot change under us because the caller
2121 * is required to hold the mmap_sem in read mode. We need the
2122 * anon_vma lock to serialize against concurrent expand_stacks.
2123 * Also guard against wrapping around to address 0.
2124 */
2125 if (address < PAGE_ALIGN(address+4))
2126 address = PAGE_ALIGN(address+4);
2127 else {
2128 vma_unlock_anon_vma(vma);
2129 return -ENOMEM;
2130 }
2131 error = 0;
2132
2133 /* Somebody else might have raced and expanded it already */
2134 if (address > vma->vm_end) {
2135 unsigned long size, grow;
2136
2137 size = address - vma->vm_start;
2138 grow = (address - vma->vm_end) >> PAGE_SHIFT;
2139
2140 error = -ENOMEM;
2141 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2142 error = acct_stack_growth(vma, size, grow);
2143 if (!error) {
2144 /*
2145 * vma_gap_update() doesn't support concurrent
2146 * updates, but we only hold a shared mmap_sem
2147 * lock here, so we need to protect against
2148 * concurrent vma expansions.
2149 * vma_lock_anon_vma() doesn't help here, as
2150 * we don't guarantee that all growable vmas
2151 * in a mm share the same root anon vma.
2152 * So, we reuse mm->page_table_lock to guard
2153 * against concurrent vma expansions.
2154 */
2155 spin_lock(&vma->vm_mm->page_table_lock);
2156 anon_vma_interval_tree_pre_update_vma(vma);
2157 vma->vm_end = address;
2158 anon_vma_interval_tree_post_update_vma(vma);
2159 if (vma->vm_next)
2160 vma_gap_update(vma->vm_next);
2161 else
2162 vma->vm_mm->highest_vm_end = address;
2163 spin_unlock(&vma->vm_mm->page_table_lock);
2164
2165 perf_event_mmap(vma);
2166 }
2167 }
2168 }
2169 vma_unlock_anon_vma(vma);
2170 khugepaged_enter_vma_merge(vma);
2171 validate_mm(vma->vm_mm);
2172 return error;
2173}
2174#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2175
2176/*
2177 * vma is the first one with address < vma->vm_start. Have to extend vma.
2178 */
2179int expand_downwards(struct vm_area_struct *vma,
2180 unsigned long address)
2181{
2182 int error;
2183
2184 /*
2185 * We must make sure the anon_vma is allocated
2186 * so that the anon_vma locking is not a noop.
2187 */
2188 if (unlikely(anon_vma_prepare(vma)))
2189 return -ENOMEM;
2190
2191 address &= PAGE_MASK;
2192 error = security_mmap_addr(address);
2193 if (error)
2194 return error;
2195
2196 vma_lock_anon_vma(vma);
2197
2198 /*
2199 * vma->vm_start/vm_end cannot change under us because the caller
2200 * is required to hold the mmap_sem in read mode. We need the
2201 * anon_vma lock to serialize against concurrent expand_stacks.
2202 */
2203
2204 /* Somebody else might have raced and expanded it already */
2205 if (address < vma->vm_start) {
2206 unsigned long size, grow;
2207
2208 size = vma->vm_end - address;
2209 grow = (vma->vm_start - address) >> PAGE_SHIFT;
2210
2211 error = -ENOMEM;
2212 if (grow <= vma->vm_pgoff) {
2213 error = acct_stack_growth(vma, size, grow);
2214 if (!error) {
2215 /*
2216 * vma_gap_update() doesn't support concurrent
2217 * updates, but we only hold a shared mmap_sem
2218 * lock here, so we need to protect against
2219 * concurrent vma expansions.
2220 * vma_lock_anon_vma() doesn't help here, as
2221 * we don't guarantee that all growable vmas
2222 * in a mm share the same root anon vma.
2223 * So, we reuse mm->page_table_lock to guard
2224 * against concurrent vma expansions.
2225 */
2226 spin_lock(&vma->vm_mm->page_table_lock);
2227 anon_vma_interval_tree_pre_update_vma(vma);
2228 vma->vm_start = address;
2229 vma->vm_pgoff -= grow;
2230 anon_vma_interval_tree_post_update_vma(vma);
2231 vma_gap_update(vma);
2232 spin_unlock(&vma->vm_mm->page_table_lock);
2233
2234 perf_event_mmap(vma);
2235 }
2236 }
2237 }
2238 vma_unlock_anon_vma(vma);
2239 khugepaged_enter_vma_merge(vma);
2240 validate_mm(vma->vm_mm);
2241 return error;
2242}
2243
2244/*
2245 * Note how expand_stack() refuses to expand the stack all the way to
2246 * abut the next virtual mapping, *unless* that mapping itself is also
2247 * a stack mapping. We want to leave room for a guard page, after all
2248 * (the guard page itself is not added here, that is done by the
2249 * actual page faulting logic)
2250 *
2251 * This matches the behavior of the guard page logic (see mm/memory.c:
2252 * check_stack_guard_page()), which only allows the guard page to be
2253 * removed under these circumstances.
2254 */
2255#ifdef CONFIG_STACK_GROWSUP
2256int expand_stack(struct vm_area_struct *vma, unsigned long address)
2257{
2258 struct vm_area_struct *next;
2259
2260 address &= PAGE_MASK;
2261 next = vma->vm_next;
2262 if (next && next->vm_start == address + PAGE_SIZE) {
2263 if (!(next->vm_flags & VM_GROWSUP))
2264 return -ENOMEM;
2265 }
2266 return expand_upwards(vma, address);
2267}
2268
2269struct vm_area_struct *
2270find_extend_vma(struct mm_struct *mm, unsigned long addr)
2271{
2272 struct vm_area_struct *vma, *prev;
2273
2274 addr &= PAGE_MASK;
2275 vma = find_vma_prev(mm, addr, &prev);
2276 if (vma && (vma->vm_start <= addr))
2277 return vma;
2278 if (!prev || expand_stack(prev, addr))
2279 return NULL;
2280 if (prev->vm_flags & VM_LOCKED)
2281 __mlock_vma_pages_range(prev, addr, prev->vm_end, NULL);
2282 return prev;
2283}
2284#else
2285int expand_stack(struct vm_area_struct *vma, unsigned long address)
2286{
2287 struct vm_area_struct *prev;
2288
2289 address &= PAGE_MASK;
2290 prev = vma->vm_prev;
2291 if (prev && prev->vm_end == address) {
2292 if (!(prev->vm_flags & VM_GROWSDOWN))
2293 return -ENOMEM;
2294 }
2295 return expand_downwards(vma, address);
2296}
2297
2298struct vm_area_struct *
2299find_extend_vma(struct mm_struct * mm, unsigned long addr)
2300{
2301 struct vm_area_struct * vma;
2302 unsigned long start;
2303
2304 addr &= PAGE_MASK;
2305 vma = find_vma(mm,addr);
2306 if (!vma)
2307 return NULL;
2308 if (vma->vm_start <= addr)
2309 return vma;
2310 if (!(vma->vm_flags & VM_GROWSDOWN))
2311 return NULL;
2312 start = vma->vm_start;
2313 if (expand_stack(vma, addr))
2314 return NULL;
2315 if (vma->vm_flags & VM_LOCKED)
2316 __mlock_vma_pages_range(vma, addr, start, NULL);
2317 return vma;
2318}
2319#endif
2320
2321/*
2322 * Ok - we have the memory areas we should free on the vma list,
2323 * so release them, and do the vma updates.
2324 *
2325 * Called with the mm semaphore held.
2326 */
2327static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
2328{
2329 unsigned long nr_accounted = 0;
2330
2331 /* Update high watermark before we lower total_vm */
2332 update_hiwater_vm(mm);
2333 do {
2334 long nrpages = vma_pages(vma);
2335
2336 if (vma->vm_flags & VM_ACCOUNT)
2337 nr_accounted += nrpages;
2338 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
2339 vma = remove_vma(vma);
2340 } while (vma);
2341 vm_unacct_memory(nr_accounted);
2342 validate_mm(mm);
2343}
2344
2345/*
2346 * Get rid of page table information in the indicated region.
2347 *
2348 * Called with the mm semaphore held.
2349 */
2350static void unmap_region(struct mm_struct *mm,
2351 struct vm_area_struct *vma, struct vm_area_struct *prev,
2352 unsigned long start, unsigned long end)
2353{
2354 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
2355 struct mmu_gather tlb;
2356
2357 lru_add_drain();
2358 tlb_gather_mmu(&tlb, mm, start, end);
2359 update_hiwater_rss(mm);
2360 unmap_vmas(&tlb, vma, start, end);
2361 free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2362 next ? next->vm_start : USER_PGTABLES_CEILING);
2363 tlb_finish_mmu(&tlb, start, end);
2364}
2365
2366/*
2367 * Create a list of vma's touched by the unmap, removing them from the mm's
2368 * vma list as we go..
2369 */
2370static void
2371detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
2372 struct vm_area_struct *prev, unsigned long end)
2373{
2374 struct vm_area_struct **insertion_point;
2375 struct vm_area_struct *tail_vma = NULL;
2376
2377 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2378 vma->vm_prev = NULL;
2379 do {
2380 vma_rb_erase(vma, &mm->mm_rb);
2381 mm->map_count--;
2382 tail_vma = vma;
2383 vma = vma->vm_next;
2384 } while (vma && vma->vm_start < end);
2385 *insertion_point = vma;
2386 if (vma) {
2387 vma->vm_prev = prev;
2388 vma_gap_update(vma);
2389 } else
2390 mm->highest_vm_end = prev ? prev->vm_end : 0;
2391 tail_vma->vm_next = NULL;
2392
2393 /* Kill the cache */
2394 vmacache_invalidate(mm);
2395}
2396
2397/*
2398 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
2399 * munmap path where it doesn't make sense to fail.
2400 */
2401static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
2402 unsigned long addr, int new_below)
2403{
2404 struct vm_area_struct *new;
2405 int err = -ENOMEM;
2406
2407 if (is_vm_hugetlb_page(vma) && (addr &
2408 ~(huge_page_mask(hstate_vma(vma)))))
2409 return -EINVAL;
2410
2411 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2412 if (!new)
2413 goto out_err;
2414
2415 /* most fields are the same, copy all, and then fixup */
2416 *new = *vma;
2417
2418 INIT_LIST_HEAD(&new->anon_vma_chain);
2419
2420 if (new_below)
2421 new->vm_end = addr;
2422 else {
2423 new->vm_start = addr;
2424 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2425 }
2426
2427 err = vma_dup_policy(vma, new);
2428 if (err)
2429 goto out_free_vma;
2430
2431 if (anon_vma_clone(new, vma))
2432 goto out_free_mpol;
2433
2434 if (new->vm_file)
2435 get_file(new->vm_file);
2436
2437 if (new->vm_ops && new->vm_ops->open)
2438 new->vm_ops->open(new);
2439
2440 if (new_below)
2441 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2442 ((addr - new->vm_start) >> PAGE_SHIFT), new);
2443 else
2444 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2445
2446 /* Success. */
2447 if (!err)
2448 return 0;
2449
2450 /* Clean everything up if vma_adjust failed. */
2451 if (new->vm_ops && new->vm_ops->close)
2452 new->vm_ops->close(new);
2453 if (new->vm_file)
2454 fput(new->vm_file);
2455 unlink_anon_vmas(new);
2456 out_free_mpol:
2457 mpol_put(vma_policy(new));
2458 out_free_vma:
2459 kmem_cache_free(vm_area_cachep, new);
2460 out_err:
2461 return err;
2462}
2463
2464/*
2465 * Split a vma into two pieces at address 'addr', a new vma is allocated
2466 * either for the first part or the tail.
2467 */
2468int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2469 unsigned long addr, int new_below)
2470{
2471 if (mm->map_count >= sysctl_max_map_count)
2472 return -ENOMEM;
2473
2474 return __split_vma(mm, vma, addr, new_below);
2475}
2476
2477/* Munmap is split into 2 main parts -- this part which finds
2478 * what needs doing, and the areas themselves, which do the
2479 * work. This now handles partial unmappings.
2480 * Jeremy Fitzhardinge <jeremy@goop.org>
2481 */
2482int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2483{
2484 unsigned long end;
2485 struct vm_area_struct *vma, *prev, *last;
2486
2487 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
2488 return -EINVAL;
2489
2490 if ((len = PAGE_ALIGN(len)) == 0)
2491 return -EINVAL;
2492
2493 /* Find the first overlapping VMA */
2494 vma = find_vma(mm, start);
2495 if (!vma)
2496 return 0;
2497 prev = vma->vm_prev;
2498 /* we have start < vma->vm_end */
2499
2500 /* if it doesn't overlap, we have nothing.. */
2501 end = start + len;
2502 if (vma->vm_start >= end)
2503 return 0;
2504
2505 /*
2506 * If we need to split any vma, do it now to save pain later.
2507 *
2508 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2509 * unmapped vm_area_struct will remain in use: so lower split_vma
2510 * places tmp vma above, and higher split_vma places tmp vma below.
2511 */
2512 if (start > vma->vm_start) {
2513 int error;
2514
2515 /*
2516 * Make sure that map_count on return from munmap() will
2517 * not exceed its limit; but let map_count go just above
2518 * its limit temporarily, to help free resources as expected.
2519 */
2520 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2521 return -ENOMEM;
2522
2523 error = __split_vma(mm, vma, start, 0);
2524 if (error)
2525 return error;
2526 prev = vma;
2527 }
2528
2529 /* Does it split the last one? */
2530 last = find_vma(mm, end);
2531 if (last && end > last->vm_start) {
2532 int error = __split_vma(mm, last, end, 1);
2533 if (error)
2534 return error;
2535 }
2536 vma = prev? prev->vm_next: mm->mmap;
2537
2538 /*
2539 * unlock any mlock()ed ranges before detaching vmas
2540 */
2541 if (mm->locked_vm) {
2542 struct vm_area_struct *tmp = vma;
2543 while (tmp && tmp->vm_start < end) {
2544 if (tmp->vm_flags & VM_LOCKED) {
2545 mm->locked_vm -= vma_pages(tmp);
2546 munlock_vma_pages_all(tmp);
2547 }
2548 tmp = tmp->vm_next;
2549 }
2550 }
2551
2552 /*
2553 * Remove the vma's, and unmap the actual pages
2554 */
2555 detach_vmas_to_be_unmapped(mm, vma, prev, end);
2556 unmap_region(mm, vma, prev, start, end);
2557
2558 /* Fix up all other VM information */
2559 remove_vma_list(mm, vma);
2560
2561 return 0;
2562}
2563
2564int vm_munmap(unsigned long start, size_t len)
2565{
2566 int ret;
2567 struct mm_struct *mm = current->mm;
2568
2569 down_write(&mm->mmap_sem);
2570 ret = do_munmap(mm, start, len);
2571 up_write(&mm->mmap_sem);
2572 return ret;
2573}
2574EXPORT_SYMBOL(vm_munmap);
2575
2576SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2577{
2578 profile_munmap(addr);
2579 return vm_munmap(addr, len);
2580}
2581
2582static inline void verify_mm_writelocked(struct mm_struct *mm)
2583{
2584#ifdef CONFIG_DEBUG_VM
2585 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2586 WARN_ON(1);
2587 up_read(&mm->mmap_sem);
2588 }
2589#endif
2590}
2591
2592/*
2593 * this is really a simplified "do_mmap". it only handles
2594 * anonymous maps. eventually we may be able to do some
2595 * brk-specific accounting here.
2596 */
2597static unsigned long do_brk(unsigned long addr, unsigned long len)
2598{
2599 struct mm_struct * mm = current->mm;
2600 struct vm_area_struct * vma, * prev;
2601 unsigned long flags;
2602 struct rb_node ** rb_link, * rb_parent;
2603 pgoff_t pgoff = addr >> PAGE_SHIFT;
2604 int error;
2605
2606 len = PAGE_ALIGN(len);
2607 if (!len)
2608 return addr;
2609
2610 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2611
2612 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2613 if (error & ~PAGE_MASK)
2614 return error;
2615
2616 error = mlock_future_check(mm, mm->def_flags, len);
2617 if (error)
2618 return error;
2619
2620 /*
2621 * mm->mmap_sem is required to protect against another thread
2622 * changing the mappings in case we sleep.
2623 */
2624 verify_mm_writelocked(mm);
2625
2626 /*
2627 * Clear old maps. this also does some error checking for us
2628 */
2629 munmap_back:
2630 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
2631 if (do_munmap(mm, addr, len))
2632 return -ENOMEM;
2633 goto munmap_back;
2634 }
2635
2636 /* Check against address space limits *after* clearing old maps... */
2637 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2638 return -ENOMEM;
2639
2640 if (mm->map_count > sysctl_max_map_count)
2641 return -ENOMEM;
2642
2643 if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
2644 return -ENOMEM;
2645
2646 /* Can we just expand an old private anonymous mapping? */
2647 vma = vma_merge(mm, prev, addr, addr + len, flags,
2648 NULL, NULL, pgoff, NULL);
2649 if (vma)
2650 goto out;
2651
2652 /*
2653 * create a vma struct for an anonymous mapping
2654 */
2655 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2656 if (!vma) {
2657 vm_unacct_memory(len >> PAGE_SHIFT);
2658 return -ENOMEM;
2659 }
2660
2661 INIT_LIST_HEAD(&vma->anon_vma_chain);
2662 vma->vm_mm = mm;
2663 vma->vm_start = addr;
2664 vma->vm_end = addr + len;
2665 vma->vm_pgoff = pgoff;
2666 vma->vm_flags = flags;
2667 vma->vm_page_prot = vm_get_page_prot(flags);
2668 vma_link(mm, vma, prev, rb_link, rb_parent);
2669out:
2670 perf_event_mmap(vma);
2671 mm->total_vm += len >> PAGE_SHIFT;
2672 if (flags & VM_LOCKED)
2673 mm->locked_vm += (len >> PAGE_SHIFT);
2674 vma->vm_flags |= VM_SOFTDIRTY;
2675 return addr;
2676}
2677
2678unsigned long vm_brk(unsigned long addr, unsigned long len)
2679{
2680 struct mm_struct *mm = current->mm;
2681 unsigned long ret;
2682 bool populate;
2683
2684 down_write(&mm->mmap_sem);
2685 ret = do_brk(addr, len);
2686 populate = ((mm->def_flags & VM_LOCKED) != 0);
2687 up_write(&mm->mmap_sem);
2688 if (populate)
2689 mm_populate(addr, len);
2690 return ret;
2691}
2692EXPORT_SYMBOL(vm_brk);
2693
2694/* Release all mmaps. */
2695void exit_mmap(struct mm_struct *mm)
2696{
2697 struct mmu_gather tlb;
2698 struct vm_area_struct *vma;
2699 unsigned long nr_accounted = 0;
2700
2701 /* mm's last user has gone, and its about to be pulled down */
2702 mmu_notifier_release(mm);
2703
2704 if (mm->locked_vm) {
2705 vma = mm->mmap;
2706 while (vma) {
2707 if (vma->vm_flags & VM_LOCKED)
2708 munlock_vma_pages_all(vma);
2709 vma = vma->vm_next;
2710 }
2711 }
2712
2713 arch_exit_mmap(mm);
2714
2715 vma = mm->mmap;
2716 if (!vma) /* Can happen if dup_mmap() received an OOM */
2717 return;
2718
2719 lru_add_drain();
2720 flush_cache_mm(mm);
2721 tlb_gather_mmu(&tlb, mm, 0, -1);
2722 /* update_hiwater_rss(mm) here? but nobody should be looking */
2723 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2724 unmap_vmas(&tlb, vma, 0, -1);
2725
2726 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
2727 tlb_finish_mmu(&tlb, 0, -1);
2728
2729 /*
2730 * Walk the list again, actually closing and freeing it,
2731 * with preemption enabled, without holding any MM locks.
2732 */
2733 while (vma) {
2734 if (vma->vm_flags & VM_ACCOUNT)
2735 nr_accounted += vma_pages(vma);
2736 vma = remove_vma(vma);
2737 }
2738 vm_unacct_memory(nr_accounted);
2739
2740 WARN_ON(atomic_long_read(&mm->nr_ptes) >
2741 (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2742}
2743
2744/* Insert vm structure into process list sorted by address
2745 * and into the inode's i_mmap tree. If vm_file is non-NULL
2746 * then i_mmap_mutex is taken here.
2747 */
2748int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
2749{
2750 struct vm_area_struct *prev;
2751 struct rb_node **rb_link, *rb_parent;
2752
2753 /*
2754 * The vm_pgoff of a purely anonymous vma should be irrelevant
2755 * until its first write fault, when page's anon_vma and index
2756 * are set. But now set the vm_pgoff it will almost certainly
2757 * end up with (unless mremap moves it elsewhere before that
2758 * first wfault), so /proc/pid/maps tells a consistent story.
2759 *
2760 * By setting it to reflect the virtual start address of the
2761 * vma, merges and splits can happen in a seamless way, just
2762 * using the existing file pgoff checks and manipulations.
2763 * Similarly in do_mmap_pgoff and in do_brk.
2764 */
2765 if (!vma->vm_file) {
2766 BUG_ON(vma->anon_vma);
2767 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2768 }
2769 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
2770 &prev, &rb_link, &rb_parent))
2771 return -ENOMEM;
2772 if ((vma->vm_flags & VM_ACCOUNT) &&
2773 security_vm_enough_memory_mm(mm, vma_pages(vma)))
2774 return -ENOMEM;
2775
2776 vma_link(mm, vma, prev, rb_link, rb_parent);
2777 return 0;
2778}
2779
2780/*
2781 * Copy the vma structure to a new location in the same mm,
2782 * prior to moving page table entries, to effect an mremap move.
2783 */
2784struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2785 unsigned long addr, unsigned long len, pgoff_t pgoff,
2786 bool *need_rmap_locks)
2787{
2788 struct vm_area_struct *vma = *vmap;
2789 unsigned long vma_start = vma->vm_start;
2790 struct mm_struct *mm = vma->vm_mm;
2791 struct vm_area_struct *new_vma, *prev;
2792 struct rb_node **rb_link, *rb_parent;
2793 bool faulted_in_anon_vma = true;
2794
2795 /*
2796 * If anonymous vma has not yet been faulted, update new pgoff
2797 * to match new location, to increase its chance of merging.
2798 */
2799 if (unlikely(!vma->vm_file && !vma->anon_vma)) {
2800 pgoff = addr >> PAGE_SHIFT;
2801 faulted_in_anon_vma = false;
2802 }
2803
2804 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
2805 return NULL; /* should never get here */
2806 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2807 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2808 if (new_vma) {
2809 /*
2810 * Source vma may have been merged into new_vma
2811 */
2812 if (unlikely(vma_start >= new_vma->vm_start &&
2813 vma_start < new_vma->vm_end)) {
2814 /*
2815 * The only way we can get a vma_merge with
2816 * self during an mremap is if the vma hasn't
2817 * been faulted in yet and we were allowed to
2818 * reset the dst vma->vm_pgoff to the
2819 * destination address of the mremap to allow
2820 * the merge to happen. mremap must change the
2821 * vm_pgoff linearity between src and dst vmas
2822 * (in turn preventing a vma_merge) to be
2823 * safe. It is only safe to keep the vm_pgoff
2824 * linear if there are no pages mapped yet.
2825 */
2826 VM_BUG_ON(faulted_in_anon_vma);
2827 *vmap = vma = new_vma;
2828 }
2829 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
2830 } else {
2831 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2832 if (new_vma) {
2833 *new_vma = *vma;
2834 new_vma->vm_start = addr;
2835 new_vma->vm_end = addr + len;
2836 new_vma->vm_pgoff = pgoff;
2837 if (vma_dup_policy(vma, new_vma))
2838 goto out_free_vma;
2839 INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2840 if (anon_vma_clone(new_vma, vma))
2841 goto out_free_mempol;
2842 if (new_vma->vm_file)
2843 get_file(new_vma->vm_file);
2844 if (new_vma->vm_ops && new_vma->vm_ops->open)
2845 new_vma->vm_ops->open(new_vma);
2846 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2847 *need_rmap_locks = false;
2848 }
2849 }
2850 return new_vma;
2851
2852 out_free_mempol:
2853 mpol_put(vma_policy(new_vma));
2854 out_free_vma:
2855 kmem_cache_free(vm_area_cachep, new_vma);
2856 return NULL;
2857}
2858
2859/*
2860 * Return true if the calling process may expand its vm space by the passed
2861 * number of pages
2862 */
2863int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2864{
2865 unsigned long cur = mm->total_vm; /* pages */
2866 unsigned long lim;
2867
2868 lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
2869
2870 if (cur + npages > lim)
2871 return 0;
2872 return 1;
2873}
2874
2875
2876static int special_mapping_fault(struct vm_area_struct *vma,
2877 struct vm_fault *vmf)
2878{
2879 pgoff_t pgoff;
2880 struct page **pages;
2881
2882 /*
2883 * special mappings have no vm_file, and in that case, the mm
2884 * uses vm_pgoff internally. So we have to subtract it from here.
2885 * We are allowed to do this because we are the mm; do not copy
2886 * this code into drivers!
2887 */
2888 pgoff = vmf->pgoff - vma->vm_pgoff;
2889
2890 for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2891 pgoff--;
2892
2893 if (*pages) {
2894 struct page *page = *pages;
2895 get_page(page);
2896 vmf->page = page;
2897 return 0;
2898 }
2899
2900 return VM_FAULT_SIGBUS;
2901}
2902
2903/*
2904 * Having a close hook prevents vma merging regardless of flags.
2905 */
2906static void special_mapping_close(struct vm_area_struct *vma)
2907{
2908}
2909
2910static const struct vm_operations_struct special_mapping_vmops = {
2911 .close = special_mapping_close,
2912 .fault = special_mapping_fault,
2913};
2914
2915/*
2916 * Called with mm->mmap_sem held for writing.
2917 * Insert a new vma covering the given region, with the given flags.
2918 * Its pages are supplied by the given array of struct page *.
2919 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2920 * The region past the last page supplied will always produce SIGBUS.
2921 * The array pointer and the pages it points to are assumed to stay alive
2922 * for as long as this mapping might exist.
2923 */
2924struct vm_area_struct *_install_special_mapping(struct mm_struct *mm,
2925 unsigned long addr, unsigned long len,
2926 unsigned long vm_flags, struct page **pages)
2927{
2928 int ret;
2929 struct vm_area_struct *vma;
2930
2931 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2932 if (unlikely(vma == NULL))
2933 return ERR_PTR(-ENOMEM);
2934
2935 INIT_LIST_HEAD(&vma->anon_vma_chain);
2936 vma->vm_mm = mm;
2937 vma->vm_start = addr;
2938 vma->vm_end = addr + len;
2939
2940 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
2941 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2942
2943 vma->vm_ops = &special_mapping_vmops;
2944 vma->vm_private_data = pages;
2945
2946 ret = insert_vm_struct(mm, vma);
2947 if (ret)
2948 goto out;
2949
2950 mm->total_vm += len >> PAGE_SHIFT;
2951
2952 perf_event_mmap(vma);
2953
2954 return vma;
2955
2956out:
2957 kmem_cache_free(vm_area_cachep, vma);
2958 return ERR_PTR(ret);
2959}
2960
2961int install_special_mapping(struct mm_struct *mm,
2962 unsigned long addr, unsigned long len,
2963 unsigned long vm_flags, struct page **pages)
2964{
2965 struct vm_area_struct *vma = _install_special_mapping(mm,
2966 addr, len, vm_flags, pages);
2967
2968 if (IS_ERR(vma))
2969 return PTR_ERR(vma);
2970 return 0;
2971}
2972
2973static DEFINE_MUTEX(mm_all_locks_mutex);
2974
2975static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2976{
2977 if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
2978 /*
2979 * The LSB of head.next can't change from under us
2980 * because we hold the mm_all_locks_mutex.
2981 */
2982 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
2983 /*
2984 * We can safely modify head.next after taking the
2985 * anon_vma->root->rwsem. If some other vma in this mm shares
2986 * the same anon_vma we won't take it again.
2987 *
2988 * No need of atomic instructions here, head.next
2989 * can't change from under us thanks to the
2990 * anon_vma->root->rwsem.
2991 */
2992 if (__test_and_set_bit(0, (unsigned long *)
2993 &anon_vma->root->rb_root.rb_node))
2994 BUG();
2995 }
2996}
2997
2998static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2999{
3000 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3001 /*
3002 * AS_MM_ALL_LOCKS can't change from under us because
3003 * we hold the mm_all_locks_mutex.
3004 *
3005 * Operations on ->flags have to be atomic because
3006 * even if AS_MM_ALL_LOCKS is stable thanks to the
3007 * mm_all_locks_mutex, there may be other cpus
3008 * changing other bitflags in parallel to us.
3009 */
3010 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
3011 BUG();
3012 mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem);
3013 }
3014}
3015
3016/*
3017 * This operation locks against the VM for all pte/vma/mm related
3018 * operations that could ever happen on a certain mm. This includes
3019 * vmtruncate, try_to_unmap, and all page faults.
3020 *
3021 * The caller must take the mmap_sem in write mode before calling
3022 * mm_take_all_locks(). The caller isn't allowed to release the
3023 * mmap_sem until mm_drop_all_locks() returns.
3024 *
3025 * mmap_sem in write mode is required in order to block all operations
3026 * that could modify pagetables and free pages without need of
3027 * altering the vma layout (for example populate_range() with
3028 * nonlinear vmas). It's also needed in write mode to avoid new
3029 * anon_vmas to be associated with existing vmas.
3030 *
3031 * A single task can't take more than one mm_take_all_locks() in a row
3032 * or it would deadlock.
3033 *
3034 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3035 * mapping->flags avoid to take the same lock twice, if more than one
3036 * vma in this mm is backed by the same anon_vma or address_space.
3037 *
3038 * We can take all the locks in random order because the VM code
3039 * taking i_mmap_mutex or anon_vma->rwsem outside the mmap_sem never
3040 * takes more than one of them in a row. Secondly we're protected
3041 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
3042 *
3043 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3044 * that may have to take thousand of locks.
3045 *
3046 * mm_take_all_locks() can fail if it's interrupted by signals.
3047 */
3048int mm_take_all_locks(struct mm_struct *mm)
3049{
3050 struct vm_area_struct *vma;
3051 struct anon_vma_chain *avc;
3052
3053 BUG_ON(down_read_trylock(&mm->mmap_sem));
3054
3055 mutex_lock(&mm_all_locks_mutex);
3056
3057 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3058 if (signal_pending(current))
3059 goto out_unlock;
3060 if (vma->vm_file && vma->vm_file->f_mapping)
3061 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3062 }
3063
3064 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3065 if (signal_pending(current))
3066 goto out_unlock;
3067 if (vma->anon_vma)
3068 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3069 vm_lock_anon_vma(mm, avc->anon_vma);
3070 }
3071
3072 return 0;
3073
3074out_unlock:
3075 mm_drop_all_locks(mm);
3076 return -EINTR;
3077}
3078
3079static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3080{
3081 if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3082 /*
3083 * The LSB of head.next can't change to 0 from under
3084 * us because we hold the mm_all_locks_mutex.
3085 *
3086 * We must however clear the bitflag before unlocking
3087 * the vma so the users using the anon_vma->rb_root will
3088 * never see our bitflag.
3089 *
3090 * No need of atomic instructions here, head.next
3091 * can't change from under us until we release the
3092 * anon_vma->root->rwsem.
3093 */
3094 if (!__test_and_clear_bit(0, (unsigned long *)
3095 &anon_vma->root->rb_root.rb_node))
3096 BUG();
3097 anon_vma_unlock_write(anon_vma);
3098 }
3099}
3100
3101static void vm_unlock_mapping(struct address_space *mapping)
3102{
3103 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3104 /*
3105 * AS_MM_ALL_LOCKS can't change to 0 from under us
3106 * because we hold the mm_all_locks_mutex.
3107 */
3108 mutex_unlock(&mapping->i_mmap_mutex);
3109 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
3110 &mapping->flags))
3111 BUG();
3112 }
3113}
3114
3115/*
3116 * The mmap_sem cannot be released by the caller until
3117 * mm_drop_all_locks() returns.
3118 */
3119void mm_drop_all_locks(struct mm_struct *mm)
3120{
3121 struct vm_area_struct *vma;
3122 struct anon_vma_chain *avc;
3123
3124 BUG_ON(down_read_trylock(&mm->mmap_sem));
3125 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3126
3127 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3128 if (vma->anon_vma)
3129 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3130 vm_unlock_anon_vma(avc->anon_vma);
3131 if (vma->vm_file && vma->vm_file->f_mapping)
3132 vm_unlock_mapping(vma->vm_file->f_mapping);
3133 }
3134
3135 mutex_unlock(&mm_all_locks_mutex);
3136}
3137
3138/*
3139 * initialise the VMA slab
3140 */
3141void __init mmap_init(void)
3142{
3143 int ret;
3144
3145 ret = percpu_counter_init(&vm_committed_as, 0);
3146 VM_BUG_ON(ret);
3147}
3148
3149/*
3150 * Initialise sysctl_user_reserve_kbytes.
3151 *
3152 * This is intended to prevent a user from starting a single memory hogging
3153 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3154 * mode.
3155 *
3156 * The default value is min(3% of free memory, 128MB)
3157 * 128MB is enough to recover with sshd/login, bash, and top/kill.
3158 */
3159static int init_user_reserve(void)
3160{
3161 unsigned long free_kbytes;
3162
3163 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3164
3165 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
3166 return 0;
3167}
3168subsys_initcall(init_user_reserve);
3169
3170/*
3171 * Initialise sysctl_admin_reserve_kbytes.
3172 *
3173 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3174 * to log in and kill a memory hogging process.
3175 *
3176 * Systems with more than 256MB will reserve 8MB, enough to recover
3177 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3178 * only reserve 3% of free pages by default.
3179 */
3180static int init_admin_reserve(void)
3181{
3182 unsigned long free_kbytes;
3183
3184 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3185
3186 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
3187 return 0;
3188}
3189subsys_initcall(init_admin_reserve);
3190
3191/*
3192 * Reinititalise user and admin reserves if memory is added or removed.
3193 *
3194 * The default user reserve max is 128MB, and the default max for the
3195 * admin reserve is 8MB. These are usually, but not always, enough to
3196 * enable recovery from a memory hogging process using login/sshd, a shell,
3197 * and tools like top. It may make sense to increase or even disable the
3198 * reserve depending on the existence of swap or variations in the recovery
3199 * tools. So, the admin may have changed them.
3200 *
3201 * If memory is added and the reserves have been eliminated or increased above
3202 * the default max, then we'll trust the admin.
3203 *
3204 * If memory is removed and there isn't enough free memory, then we
3205 * need to reset the reserves.
3206 *
3207 * Otherwise keep the reserve set by the admin.
3208 */
3209static int reserve_mem_notifier(struct notifier_block *nb,
3210 unsigned long action, void *data)
3211{
3212 unsigned long tmp, free_kbytes;
3213
3214 switch (action) {
3215 case MEM_ONLINE:
3216 /* Default max is 128MB. Leave alone if modified by operator. */
3217 tmp = sysctl_user_reserve_kbytes;
3218 if (0 < tmp && tmp < (1UL << 17))
3219 init_user_reserve();
3220
3221 /* Default max is 8MB. Leave alone if modified by operator. */
3222 tmp = sysctl_admin_reserve_kbytes;
3223 if (0 < tmp && tmp < (1UL << 13))
3224 init_admin_reserve();
3225
3226 break;
3227 case MEM_OFFLINE:
3228 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3229
3230 if (sysctl_user_reserve_kbytes > free_kbytes) {
3231 init_user_reserve();
3232 pr_info("vm.user_reserve_kbytes reset to %lu\n",
3233 sysctl_user_reserve_kbytes);
3234 }
3235
3236 if (sysctl_admin_reserve_kbytes > free_kbytes) {
3237 init_admin_reserve();
3238 pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3239 sysctl_admin_reserve_kbytes);
3240 }
3241 break;
3242 default:
3243 break;
3244 }
3245 return NOTIFY_OK;
3246}
3247
3248static struct notifier_block reserve_mem_nb = {
3249 .notifier_call = reserve_mem_notifier,
3250};
3251
3252static int __meminit init_reserve_notifier(void)
3253{
3254 if (register_hotmemory_notifier(&reserve_mem_nb))
3255 printk("Failed registering memory add/remove notifier for admin reserve");
3256
3257 return 0;
3258}
3259subsys_initcall(init_reserve_notifier);