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