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