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1/*
2 * mm/mmap.c
3 *
4 * Written by obz.
5 *
6 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
7 */
8
9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11#include <linux/kernel.h>
12#include <linux/slab.h>
13#include <linux/backing-dev.h>
14#include <linux/mm.h>
15#include <linux/vmacache.h>
16#include <linux/shm.h>
17#include <linux/mman.h>
18#include <linux/pagemap.h>
19#include <linux/swap.h>
20#include <linux/syscalls.h>
21#include <linux/capability.h>
22#include <linux/init.h>
23#include <linux/file.h>
24#include <linux/fs.h>
25#include <linux/personality.h>
26#include <linux/security.h>
27#include <linux/hugetlb.h>
28#include <linux/shmem_fs.h>
29#include <linux/profile.h>
30#include <linux/export.h>
31#include <linux/mount.h>
32#include <linux/mempolicy.h>
33#include <linux/rmap.h>
34#include <linux/mmu_notifier.h>
35#include <linux/mmdebug.h>
36#include <linux/perf_event.h>
37#include <linux/audit.h>
38#include <linux/khugepaged.h>
39#include <linux/uprobes.h>
40#include <linux/rbtree_augmented.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
49#include <linux/uaccess.h>
50#include <asm/cacheflush.h>
51#include <asm/tlb.h>
52#include <asm/mmu_context.h>
53
54#include "internal.h"
55
56#ifndef arch_mmap_check
57#define arch_mmap_check(addr, len, flags) (0)
58#endif
59
60#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
61const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
62const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX;
63int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
64#endif
65#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
66const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
67const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
68int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
69#endif
70
71static bool ignore_rlimit_data;
72core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
73
74static void unmap_region(struct mm_struct *mm,
75 struct vm_area_struct *vma, struct vm_area_struct *prev,
76 unsigned long start, unsigned long end);
77
78/* description of effects of mapping type and prot in current implementation.
79 * this is due to the limited x86 page protection hardware. The expected
80 * behavior is in parens:
81 *
82 * map_type prot
83 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
84 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
85 * w: (no) no w: (no) no w: (yes) yes w: (no) no
86 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
87 *
88 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
89 * w: (no) no w: (no) no w: (copy) copy w: (no) no
90 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
91 *
92 * On arm64, PROT_EXEC has the following behaviour for both MAP_SHARED and
93 * MAP_PRIVATE:
94 * r: (no) no
95 * w: (no) no
96 * x: (yes) yes
97 */
98pgprot_t protection_map[16] __ro_after_init = {
99 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
100 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
101};
102
103#ifndef CONFIG_ARCH_HAS_FILTER_PGPROT
104static inline pgprot_t arch_filter_pgprot(pgprot_t prot)
105{
106 return prot;
107}
108#endif
109
110pgprot_t vm_get_page_prot(unsigned long vm_flags)
111{
112 pgprot_t ret = __pgprot(pgprot_val(protection_map[vm_flags &
113 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
114 pgprot_val(arch_vm_get_page_prot(vm_flags)));
115
116 return arch_filter_pgprot(ret);
117}
118EXPORT_SYMBOL(vm_get_page_prot);
119
120static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
121{
122 return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
123}
124
125/* Update vma->vm_page_prot to reflect vma->vm_flags. */
126void vma_set_page_prot(struct vm_area_struct *vma)
127{
128 unsigned long vm_flags = vma->vm_flags;
129 pgprot_t vm_page_prot;
130
131 vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
132 if (vma_wants_writenotify(vma, vm_page_prot)) {
133 vm_flags &= ~VM_SHARED;
134 vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags);
135 }
136 /* remove_protection_ptes reads vma->vm_page_prot without mmap_sem */
137 WRITE_ONCE(vma->vm_page_prot, vm_page_prot);
138}
139
140/*
141 * Requires inode->i_mapping->i_mmap_rwsem
142 */
143static void __remove_shared_vm_struct(struct vm_area_struct *vma,
144 struct file *file, struct address_space *mapping)
145{
146 if (vma->vm_flags & VM_DENYWRITE)
147 atomic_inc(&file_inode(file)->i_writecount);
148 if (vma->vm_flags & VM_SHARED)
149 mapping_unmap_writable(mapping);
150
151 flush_dcache_mmap_lock(mapping);
152 vma_interval_tree_remove(vma, &mapping->i_mmap);
153 flush_dcache_mmap_unlock(mapping);
154}
155
156/*
157 * Unlink a file-based vm structure from its interval tree, to hide
158 * vma from rmap and vmtruncate before freeing its page tables.
159 */
160void unlink_file_vma(struct vm_area_struct *vma)
161{
162 struct file *file = vma->vm_file;
163
164 if (file) {
165 struct address_space *mapping = file->f_mapping;
166 i_mmap_lock_write(mapping);
167 __remove_shared_vm_struct(vma, file, mapping);
168 i_mmap_unlock_write(mapping);
169 }
170}
171
172/*
173 * Close a vm structure and free it, returning the next.
174 */
175static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
176{
177 struct vm_area_struct *next = vma->vm_next;
178
179 might_sleep();
180 if (vma->vm_ops && vma->vm_ops->close)
181 vma->vm_ops->close(vma);
182 if (vma->vm_file)
183 fput(vma->vm_file);
184 mpol_put(vma_policy(vma));
185 kmem_cache_free(vm_area_cachep, vma);
186 return next;
187}
188
189static int do_brk(unsigned long addr, unsigned long len, struct list_head *uf);
190
191SYSCALL_DEFINE1(brk, unsigned long, brk)
192{
193 unsigned long retval;
194 unsigned long newbrk, oldbrk;
195 struct mm_struct *mm = current->mm;
196 struct vm_area_struct *next;
197 unsigned long min_brk;
198 bool populate;
199 LIST_HEAD(uf);
200
201 if (down_write_killable(&mm->mmap_sem))
202 return -EINTR;
203
204#ifdef CONFIG_COMPAT_BRK
205 /*
206 * CONFIG_COMPAT_BRK can still be overridden by setting
207 * randomize_va_space to 2, which will still cause mm->start_brk
208 * to be arbitrarily shifted
209 */
210 if (current->brk_randomized)
211 min_brk = mm->start_brk;
212 else
213 min_brk = mm->end_data;
214#else
215 min_brk = mm->start_brk;
216#endif
217 if (brk < min_brk)
218 goto out;
219
220 /*
221 * Check against rlimit here. If this check is done later after the test
222 * of oldbrk with newbrk then it can escape the test and let the data
223 * segment grow beyond its set limit the in case where the limit is
224 * not page aligned -Ram Gupta
225 */
226 if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
227 mm->end_data, mm->start_data))
228 goto out;
229
230 newbrk = PAGE_ALIGN(brk);
231 oldbrk = PAGE_ALIGN(mm->brk);
232 if (oldbrk == newbrk)
233 goto set_brk;
234
235 /* Always allow shrinking brk. */
236 if (brk <= mm->brk) {
237 if (!do_munmap(mm, newbrk, oldbrk-newbrk, &uf))
238 goto set_brk;
239 goto out;
240 }
241
242 /* Check against existing mmap mappings. */
243 next = find_vma(mm, oldbrk);
244 if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
245 goto out;
246
247 /* Ok, looks good - let it rip. */
248 if (do_brk(oldbrk, newbrk-oldbrk, &uf) < 0)
249 goto out;
250
251set_brk:
252 mm->brk = brk;
253 populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
254 up_write(&mm->mmap_sem);
255 userfaultfd_unmap_complete(mm, &uf);
256 if (populate)
257 mm_populate(oldbrk, newbrk - oldbrk);
258 return brk;
259
260out:
261 retval = mm->brk;
262 up_write(&mm->mmap_sem);
263 return retval;
264}
265
266static long vma_compute_subtree_gap(struct vm_area_struct *vma)
267{
268 unsigned long max, prev_end, subtree_gap;
269
270 /*
271 * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we
272 * allow two stack_guard_gaps between them here, and when choosing
273 * an unmapped area; whereas when expanding we only require one.
274 * That's a little inconsistent, but keeps the code here simpler.
275 */
276 max = vm_start_gap(vma);
277 if (vma->vm_prev) {
278 prev_end = vm_end_gap(vma->vm_prev);
279 if (max > prev_end)
280 max -= prev_end;
281 else
282 max = 0;
283 }
284 if (vma->vm_rb.rb_left) {
285 subtree_gap = rb_entry(vma->vm_rb.rb_left,
286 struct vm_area_struct, vm_rb)->rb_subtree_gap;
287 if (subtree_gap > max)
288 max = subtree_gap;
289 }
290 if (vma->vm_rb.rb_right) {
291 subtree_gap = rb_entry(vma->vm_rb.rb_right,
292 struct vm_area_struct, vm_rb)->rb_subtree_gap;
293 if (subtree_gap > max)
294 max = subtree_gap;
295 }
296 return max;
297}
298
299#ifdef CONFIG_DEBUG_VM_RB
300static int browse_rb(struct mm_struct *mm)
301{
302 struct rb_root *root = &mm->mm_rb;
303 int i = 0, j, bug = 0;
304 struct rb_node *nd, *pn = NULL;
305 unsigned long prev = 0, pend = 0;
306
307 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
308 struct vm_area_struct *vma;
309 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
310 if (vma->vm_start < prev) {
311 pr_emerg("vm_start %lx < prev %lx\n",
312 vma->vm_start, prev);
313 bug = 1;
314 }
315 if (vma->vm_start < pend) {
316 pr_emerg("vm_start %lx < pend %lx\n",
317 vma->vm_start, pend);
318 bug = 1;
319 }
320 if (vma->vm_start > vma->vm_end) {
321 pr_emerg("vm_start %lx > vm_end %lx\n",
322 vma->vm_start, vma->vm_end);
323 bug = 1;
324 }
325 spin_lock(&mm->page_table_lock);
326 if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
327 pr_emerg("free gap %lx, correct %lx\n",
328 vma->rb_subtree_gap,
329 vma_compute_subtree_gap(vma));
330 bug = 1;
331 }
332 spin_unlock(&mm->page_table_lock);
333 i++;
334 pn = nd;
335 prev = vma->vm_start;
336 pend = vma->vm_end;
337 }
338 j = 0;
339 for (nd = pn; nd; nd = rb_prev(nd))
340 j++;
341 if (i != j) {
342 pr_emerg("backwards %d, forwards %d\n", j, i);
343 bug = 1;
344 }
345 return bug ? -1 : i;
346}
347
348static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
349{
350 struct rb_node *nd;
351
352 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
353 struct vm_area_struct *vma;
354 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
355 VM_BUG_ON_VMA(vma != ignore &&
356 vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
357 vma);
358 }
359}
360
361static void validate_mm(struct mm_struct *mm)
362{
363 int bug = 0;
364 int i = 0;
365 unsigned long highest_address = 0;
366 struct vm_area_struct *vma = mm->mmap;
367
368 while (vma) {
369 struct anon_vma *anon_vma = vma->anon_vma;
370 struct anon_vma_chain *avc;
371
372 if (anon_vma) {
373 anon_vma_lock_read(anon_vma);
374 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
375 anon_vma_interval_tree_verify(avc);
376 anon_vma_unlock_read(anon_vma);
377 }
378
379 highest_address = vm_end_gap(vma);
380 vma = vma->vm_next;
381 i++;
382 }
383 if (i != mm->map_count) {
384 pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
385 bug = 1;
386 }
387 if (highest_address != mm->highest_vm_end) {
388 pr_emerg("mm->highest_vm_end %lx, found %lx\n",
389 mm->highest_vm_end, highest_address);
390 bug = 1;
391 }
392 i = browse_rb(mm);
393 if (i != mm->map_count) {
394 if (i != -1)
395 pr_emerg("map_count %d rb %d\n", mm->map_count, i);
396 bug = 1;
397 }
398 VM_BUG_ON_MM(bug, mm);
399}
400#else
401#define validate_mm_rb(root, ignore) do { } while (0)
402#define validate_mm(mm) do { } while (0)
403#endif
404
405RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb,
406 unsigned long, rb_subtree_gap, vma_compute_subtree_gap)
407
408/*
409 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
410 * vma->vm_prev->vm_end values changed, without modifying the vma's position
411 * in the rbtree.
412 */
413static void vma_gap_update(struct vm_area_struct *vma)
414{
415 /*
416 * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
417 * function that does exacltly what we want.
418 */
419 vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
420}
421
422static inline void vma_rb_insert(struct vm_area_struct *vma,
423 struct rb_root *root)
424{
425 /* All rb_subtree_gap values must be consistent prior to insertion */
426 validate_mm_rb(root, NULL);
427
428 rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
429}
430
431static void __vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
432{
433 /*
434 * Note rb_erase_augmented is a fairly large inline function,
435 * so make sure we instantiate it only once with our desired
436 * augmented rbtree callbacks.
437 */
438 rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
439}
440
441static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma,
442 struct rb_root *root,
443 struct vm_area_struct *ignore)
444{
445 /*
446 * All rb_subtree_gap values must be consistent prior to erase,
447 * with the possible exception of the "next" vma being erased if
448 * next->vm_start was reduced.
449 */
450 validate_mm_rb(root, ignore);
451
452 __vma_rb_erase(vma, root);
453}
454
455static __always_inline void vma_rb_erase(struct vm_area_struct *vma,
456 struct rb_root *root)
457{
458 /*
459 * All rb_subtree_gap values must be consistent prior to erase,
460 * with the possible exception of the vma being erased.
461 */
462 validate_mm_rb(root, vma);
463
464 __vma_rb_erase(vma, root);
465}
466
467/*
468 * vma has some anon_vma assigned, and is already inserted on that
469 * anon_vma's interval trees.
470 *
471 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
472 * vma must be removed from the anon_vma's interval trees using
473 * anon_vma_interval_tree_pre_update_vma().
474 *
475 * After the update, the vma will be reinserted using
476 * anon_vma_interval_tree_post_update_vma().
477 *
478 * The entire update must be protected by exclusive mmap_sem and by
479 * the root anon_vma's mutex.
480 */
481static inline void
482anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
483{
484 struct anon_vma_chain *avc;
485
486 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
487 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
488}
489
490static inline void
491anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
492{
493 struct anon_vma_chain *avc;
494
495 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
496 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
497}
498
499static int find_vma_links(struct mm_struct *mm, unsigned long addr,
500 unsigned long end, struct vm_area_struct **pprev,
501 struct rb_node ***rb_link, struct rb_node **rb_parent)
502{
503 struct rb_node **__rb_link, *__rb_parent, *rb_prev;
504
505 __rb_link = &mm->mm_rb.rb_node;
506 rb_prev = __rb_parent = NULL;
507
508 while (*__rb_link) {
509 struct vm_area_struct *vma_tmp;
510
511 __rb_parent = *__rb_link;
512 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
513
514 if (vma_tmp->vm_end > addr) {
515 /* Fail if an existing vma overlaps the area */
516 if (vma_tmp->vm_start < end)
517 return -ENOMEM;
518 __rb_link = &__rb_parent->rb_left;
519 } else {
520 rb_prev = __rb_parent;
521 __rb_link = &__rb_parent->rb_right;
522 }
523 }
524
525 *pprev = NULL;
526 if (rb_prev)
527 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
528 *rb_link = __rb_link;
529 *rb_parent = __rb_parent;
530 return 0;
531}
532
533static unsigned long count_vma_pages_range(struct mm_struct *mm,
534 unsigned long addr, unsigned long end)
535{
536 unsigned long nr_pages = 0;
537 struct vm_area_struct *vma;
538
539 /* Find first overlaping mapping */
540 vma = find_vma_intersection(mm, addr, end);
541 if (!vma)
542 return 0;
543
544 nr_pages = (min(end, vma->vm_end) -
545 max(addr, vma->vm_start)) >> PAGE_SHIFT;
546
547 /* Iterate over the rest of the overlaps */
548 for (vma = vma->vm_next; vma; vma = vma->vm_next) {
549 unsigned long overlap_len;
550
551 if (vma->vm_start > end)
552 break;
553
554 overlap_len = min(end, vma->vm_end) - vma->vm_start;
555 nr_pages += overlap_len >> PAGE_SHIFT;
556 }
557
558 return nr_pages;
559}
560
561void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
562 struct rb_node **rb_link, struct rb_node *rb_parent)
563{
564 /* Update tracking information for the gap following the new vma. */
565 if (vma->vm_next)
566 vma_gap_update(vma->vm_next);
567 else
568 mm->highest_vm_end = vm_end_gap(vma);
569
570 /*
571 * vma->vm_prev wasn't known when we followed the rbtree to find the
572 * correct insertion point for that vma. As a result, we could not
573 * update the vma vm_rb parents rb_subtree_gap values on the way down.
574 * So, we first insert the vma with a zero rb_subtree_gap value
575 * (to be consistent with what we did on the way down), and then
576 * immediately update the gap to the correct value. Finally we
577 * rebalance the rbtree after all augmented values have been set.
578 */
579 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
580 vma->rb_subtree_gap = 0;
581 vma_gap_update(vma);
582 vma_rb_insert(vma, &mm->mm_rb);
583}
584
585static void __vma_link_file(struct vm_area_struct *vma)
586{
587 struct file *file;
588
589 file = vma->vm_file;
590 if (file) {
591 struct address_space *mapping = file->f_mapping;
592
593 if (vma->vm_flags & VM_DENYWRITE)
594 atomic_dec(&file_inode(file)->i_writecount);
595 if (vma->vm_flags & VM_SHARED)
596 atomic_inc(&mapping->i_mmap_writable);
597
598 flush_dcache_mmap_lock(mapping);
599 vma_interval_tree_insert(vma, &mapping->i_mmap);
600 flush_dcache_mmap_unlock(mapping);
601 }
602}
603
604static void
605__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
606 struct vm_area_struct *prev, struct rb_node **rb_link,
607 struct rb_node *rb_parent)
608{
609 __vma_link_list(mm, vma, prev, rb_parent);
610 __vma_link_rb(mm, vma, rb_link, rb_parent);
611}
612
613static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
614 struct vm_area_struct *prev, struct rb_node **rb_link,
615 struct rb_node *rb_parent)
616{
617 struct address_space *mapping = NULL;
618
619 if (vma->vm_file) {
620 mapping = vma->vm_file->f_mapping;
621 i_mmap_lock_write(mapping);
622 }
623
624 __vma_link(mm, vma, prev, rb_link, rb_parent);
625 __vma_link_file(vma);
626
627 if (mapping)
628 i_mmap_unlock_write(mapping);
629
630 mm->map_count++;
631 validate_mm(mm);
632}
633
634/*
635 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
636 * mm's list and rbtree. It has already been inserted into the interval tree.
637 */
638static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
639{
640 struct vm_area_struct *prev;
641 struct rb_node **rb_link, *rb_parent;
642
643 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
644 &prev, &rb_link, &rb_parent))
645 BUG();
646 __vma_link(mm, vma, prev, rb_link, rb_parent);
647 mm->map_count++;
648}
649
650static __always_inline void __vma_unlink_common(struct mm_struct *mm,
651 struct vm_area_struct *vma,
652 struct vm_area_struct *prev,
653 bool has_prev,
654 struct vm_area_struct *ignore)
655{
656 struct vm_area_struct *next;
657
658 vma_rb_erase_ignore(vma, &mm->mm_rb, ignore);
659 next = vma->vm_next;
660 if (has_prev)
661 prev->vm_next = next;
662 else {
663 prev = vma->vm_prev;
664 if (prev)
665 prev->vm_next = next;
666 else
667 mm->mmap = next;
668 }
669 if (next)
670 next->vm_prev = prev;
671
672 /* Kill the cache */
673 vmacache_invalidate(mm);
674}
675
676static inline void __vma_unlink_prev(struct mm_struct *mm,
677 struct vm_area_struct *vma,
678 struct vm_area_struct *prev)
679{
680 __vma_unlink_common(mm, vma, prev, true, vma);
681}
682
683/*
684 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
685 * is already present in an i_mmap tree without adjusting the tree.
686 * The following helper function should be used when such adjustments
687 * are necessary. The "insert" vma (if any) is to be inserted
688 * before we drop the necessary locks.
689 */
690int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
691 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert,
692 struct vm_area_struct *expand)
693{
694 struct mm_struct *mm = vma->vm_mm;
695 struct vm_area_struct *next = vma->vm_next, *orig_vma = vma;
696 struct address_space *mapping = NULL;
697 struct rb_root_cached *root = NULL;
698 struct anon_vma *anon_vma = NULL;
699 struct file *file = vma->vm_file;
700 bool start_changed = false, end_changed = false;
701 long adjust_next = 0;
702 int remove_next = 0;
703
704 if (next && !insert) {
705 struct vm_area_struct *exporter = NULL, *importer = NULL;
706
707 if (end >= next->vm_end) {
708 /*
709 * vma expands, overlapping all the next, and
710 * perhaps the one after too (mprotect case 6).
711 * The only other cases that gets here are
712 * case 1, case 7 and case 8.
713 */
714 if (next == expand) {
715 /*
716 * The only case where we don't expand "vma"
717 * and we expand "next" instead is case 8.
718 */
719 VM_WARN_ON(end != next->vm_end);
720 /*
721 * remove_next == 3 means we're
722 * removing "vma" and that to do so we
723 * swapped "vma" and "next".
724 */
725 remove_next = 3;
726 VM_WARN_ON(file != next->vm_file);
727 swap(vma, next);
728 } else {
729 VM_WARN_ON(expand != vma);
730 /*
731 * case 1, 6, 7, remove_next == 2 is case 6,
732 * remove_next == 1 is case 1 or 7.
733 */
734 remove_next = 1 + (end > next->vm_end);
735 VM_WARN_ON(remove_next == 2 &&
736 end != next->vm_next->vm_end);
737 VM_WARN_ON(remove_next == 1 &&
738 end != next->vm_end);
739 /* trim end to next, for case 6 first pass */
740 end = next->vm_end;
741 }
742
743 exporter = next;
744 importer = vma;
745
746 /*
747 * If next doesn't have anon_vma, import from vma after
748 * next, if the vma overlaps with it.
749 */
750 if (remove_next == 2 && !next->anon_vma)
751 exporter = next->vm_next;
752
753 } else if (end > next->vm_start) {
754 /*
755 * vma expands, overlapping part of the next:
756 * mprotect case 5 shifting the boundary up.
757 */
758 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
759 exporter = next;
760 importer = vma;
761 VM_WARN_ON(expand != importer);
762 } else if (end < vma->vm_end) {
763 /*
764 * vma shrinks, and !insert tells it's not
765 * split_vma inserting another: so it must be
766 * mprotect case 4 shifting the boundary down.
767 */
768 adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT);
769 exporter = vma;
770 importer = next;
771 VM_WARN_ON(expand != importer);
772 }
773
774 /*
775 * Easily overlooked: when mprotect shifts the boundary,
776 * make sure the expanding vma has anon_vma set if the
777 * shrinking vma had, to cover any anon pages imported.
778 */
779 if (exporter && exporter->anon_vma && !importer->anon_vma) {
780 int error;
781
782 importer->anon_vma = exporter->anon_vma;
783 error = anon_vma_clone(importer, exporter);
784 if (error)
785 return error;
786 }
787 }
788again:
789 vma_adjust_trans_huge(orig_vma, start, end, adjust_next);
790
791 if (file) {
792 mapping = file->f_mapping;
793 root = &mapping->i_mmap;
794 uprobe_munmap(vma, vma->vm_start, vma->vm_end);
795
796 if (adjust_next)
797 uprobe_munmap(next, next->vm_start, next->vm_end);
798
799 i_mmap_lock_write(mapping);
800 if (insert) {
801 /*
802 * Put into interval tree now, so instantiated pages
803 * are visible to arm/parisc __flush_dcache_page
804 * throughout; but we cannot insert into address
805 * space until vma start or end is updated.
806 */
807 __vma_link_file(insert);
808 }
809 }
810
811 anon_vma = vma->anon_vma;
812 if (!anon_vma && adjust_next)
813 anon_vma = next->anon_vma;
814 if (anon_vma) {
815 VM_WARN_ON(adjust_next && next->anon_vma &&
816 anon_vma != next->anon_vma);
817 anon_vma_lock_write(anon_vma);
818 anon_vma_interval_tree_pre_update_vma(vma);
819 if (adjust_next)
820 anon_vma_interval_tree_pre_update_vma(next);
821 }
822
823 if (root) {
824 flush_dcache_mmap_lock(mapping);
825 vma_interval_tree_remove(vma, root);
826 if (adjust_next)
827 vma_interval_tree_remove(next, root);
828 }
829
830 if (start != vma->vm_start) {
831 vma->vm_start = start;
832 start_changed = true;
833 }
834 if (end != vma->vm_end) {
835 vma->vm_end = end;
836 end_changed = true;
837 }
838 vma->vm_pgoff = pgoff;
839 if (adjust_next) {
840 next->vm_start += adjust_next << PAGE_SHIFT;
841 next->vm_pgoff += adjust_next;
842 }
843
844 if (root) {
845 if (adjust_next)
846 vma_interval_tree_insert(next, root);
847 vma_interval_tree_insert(vma, root);
848 flush_dcache_mmap_unlock(mapping);
849 }
850
851 if (remove_next) {
852 /*
853 * vma_merge has merged next into vma, and needs
854 * us to remove next before dropping the locks.
855 */
856 if (remove_next != 3)
857 __vma_unlink_prev(mm, next, vma);
858 else
859 /*
860 * vma is not before next if they've been
861 * swapped.
862 *
863 * pre-swap() next->vm_start was reduced so
864 * tell validate_mm_rb to ignore pre-swap()
865 * "next" (which is stored in post-swap()
866 * "vma").
867 */
868 __vma_unlink_common(mm, next, NULL, false, vma);
869 if (file)
870 __remove_shared_vm_struct(next, file, mapping);
871 } else if (insert) {
872 /*
873 * split_vma has split insert from vma, and needs
874 * us to insert it before dropping the locks
875 * (it may either follow vma or precede it).
876 */
877 __insert_vm_struct(mm, insert);
878 } else {
879 if (start_changed)
880 vma_gap_update(vma);
881 if (end_changed) {
882 if (!next)
883 mm->highest_vm_end = vm_end_gap(vma);
884 else if (!adjust_next)
885 vma_gap_update(next);
886 }
887 }
888
889 if (anon_vma) {
890 anon_vma_interval_tree_post_update_vma(vma);
891 if (adjust_next)
892 anon_vma_interval_tree_post_update_vma(next);
893 anon_vma_unlock_write(anon_vma);
894 }
895 if (mapping)
896 i_mmap_unlock_write(mapping);
897
898 if (root) {
899 uprobe_mmap(vma);
900
901 if (adjust_next)
902 uprobe_mmap(next);
903 }
904
905 if (remove_next) {
906 if (file) {
907 uprobe_munmap(next, next->vm_start, next->vm_end);
908 fput(file);
909 }
910 if (next->anon_vma)
911 anon_vma_merge(vma, next);
912 mm->map_count--;
913 mpol_put(vma_policy(next));
914 kmem_cache_free(vm_area_cachep, next);
915 /*
916 * In mprotect's case 6 (see comments on vma_merge),
917 * we must remove another next too. It would clutter
918 * up the code too much to do both in one go.
919 */
920 if (remove_next != 3) {
921 /*
922 * If "next" was removed and vma->vm_end was
923 * expanded (up) over it, in turn
924 * "next->vm_prev->vm_end" changed and the
925 * "vma->vm_next" gap must be updated.
926 */
927 next = vma->vm_next;
928 } else {
929 /*
930 * For the scope of the comment "next" and
931 * "vma" considered pre-swap(): if "vma" was
932 * removed, next->vm_start was expanded (down)
933 * over it and the "next" gap must be updated.
934 * Because of the swap() the post-swap() "vma"
935 * actually points to pre-swap() "next"
936 * (post-swap() "next" as opposed is now a
937 * dangling pointer).
938 */
939 next = vma;
940 }
941 if (remove_next == 2) {
942 remove_next = 1;
943 end = next->vm_end;
944 goto again;
945 }
946 else if (next)
947 vma_gap_update(next);
948 else {
949 /*
950 * If remove_next == 2 we obviously can't
951 * reach this path.
952 *
953 * If remove_next == 3 we can't reach this
954 * path because pre-swap() next is always not
955 * NULL. pre-swap() "next" is not being
956 * removed and its next->vm_end is not altered
957 * (and furthermore "end" already matches
958 * next->vm_end in remove_next == 3).
959 *
960 * We reach this only in the remove_next == 1
961 * case if the "next" vma that was removed was
962 * the highest vma of the mm. However in such
963 * case next->vm_end == "end" and the extended
964 * "vma" has vma->vm_end == next->vm_end so
965 * mm->highest_vm_end doesn't need any update
966 * in remove_next == 1 case.
967 */
968 VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
969 }
970 }
971 if (insert && file)
972 uprobe_mmap(insert);
973
974 validate_mm(mm);
975
976 return 0;
977}
978
979/*
980 * If the vma has a ->close operation then the driver probably needs to release
981 * per-vma resources, so we don't attempt to merge those.
982 */
983static inline int is_mergeable_vma(struct vm_area_struct *vma,
984 struct file *file, unsigned long vm_flags,
985 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
986{
987 /*
988 * VM_SOFTDIRTY should not prevent from VMA merging, if we
989 * match the flags but dirty bit -- the caller should mark
990 * merged VMA as dirty. If dirty bit won't be excluded from
991 * comparison, we increase pressue on the memory system forcing
992 * the kernel to generate new VMAs when old one could be
993 * extended instead.
994 */
995 if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
996 return 0;
997 if (vma->vm_file != file)
998 return 0;
999 if (vma->vm_ops && vma->vm_ops->close)
1000 return 0;
1001 if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
1002 return 0;
1003 return 1;
1004}
1005
1006static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
1007 struct anon_vma *anon_vma2,
1008 struct vm_area_struct *vma)
1009{
1010 /*
1011 * The list_is_singular() test is to avoid merging VMA cloned from
1012 * parents. This can improve scalability caused by anon_vma lock.
1013 */
1014 if ((!anon_vma1 || !anon_vma2) && (!vma ||
1015 list_is_singular(&vma->anon_vma_chain)))
1016 return 1;
1017 return anon_vma1 == anon_vma2;
1018}
1019
1020/*
1021 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
1022 * in front of (at a lower virtual address and file offset than) the vma.
1023 *
1024 * We cannot merge two vmas if they have differently assigned (non-NULL)
1025 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
1026 *
1027 * We don't check here for the merged mmap wrapping around the end of pagecache
1028 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
1029 * wrap, nor mmaps which cover the final page at index -1UL.
1030 */
1031static int
1032can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
1033 struct anon_vma *anon_vma, struct file *file,
1034 pgoff_t vm_pgoff,
1035 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1036{
1037 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
1038 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
1039 if (vma->vm_pgoff == vm_pgoff)
1040 return 1;
1041 }
1042 return 0;
1043}
1044
1045/*
1046 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
1047 * beyond (at a higher virtual address and file offset than) the vma.
1048 *
1049 * We cannot merge two vmas if they have differently assigned (non-NULL)
1050 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
1051 */
1052static int
1053can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
1054 struct anon_vma *anon_vma, struct file *file,
1055 pgoff_t vm_pgoff,
1056 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1057{
1058 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
1059 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
1060 pgoff_t vm_pglen;
1061 vm_pglen = vma_pages(vma);
1062 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
1063 return 1;
1064 }
1065 return 0;
1066}
1067
1068/*
1069 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
1070 * whether that can be merged with its predecessor or its successor.
1071 * Or both (it neatly fills a hole).
1072 *
1073 * In most cases - when called for mmap, brk or mremap - [addr,end) is
1074 * certain not to be mapped by the time vma_merge is called; but when
1075 * called for mprotect, it is certain to be already mapped (either at
1076 * an offset within prev, or at the start of next), and the flags of
1077 * this area are about to be changed to vm_flags - and the no-change
1078 * case has already been eliminated.
1079 *
1080 * The following mprotect cases have to be considered, where AAAA is
1081 * the area passed down from mprotect_fixup, never extending beyond one
1082 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
1083 *
1084 * AAAA AAAA AAAA AAAA
1085 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
1086 * cannot merge might become might become might become
1087 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
1088 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
1089 * mremap move: PPPPXXXXXXXX 8
1090 * AAAA
1091 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
1092 * might become case 1 below case 2 below case 3 below
1093 *
1094 * It is important for case 8 that the the vma NNNN overlapping the
1095 * region AAAA is never going to extended over XXXX. Instead XXXX must
1096 * be extended in region AAAA and NNNN must be removed. This way in
1097 * all cases where vma_merge succeeds, the moment vma_adjust drops the
1098 * rmap_locks, the properties of the merged vma will be already
1099 * correct for the whole merged range. Some of those properties like
1100 * vm_page_prot/vm_flags may be accessed by rmap_walks and they must
1101 * be correct for the whole merged range immediately after the
1102 * rmap_locks are released. Otherwise if XXXX would be removed and
1103 * NNNN would be extended over the XXXX range, remove_migration_ptes
1104 * or other rmap walkers (if working on addresses beyond the "end"
1105 * parameter) may establish ptes with the wrong permissions of NNNN
1106 * instead of the right permissions of XXXX.
1107 */
1108struct vm_area_struct *vma_merge(struct mm_struct *mm,
1109 struct vm_area_struct *prev, unsigned long addr,
1110 unsigned long end, unsigned long vm_flags,
1111 struct anon_vma *anon_vma, struct file *file,
1112 pgoff_t pgoff, struct mempolicy *policy,
1113 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1114{
1115 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
1116 struct vm_area_struct *area, *next;
1117 int err;
1118
1119 /*
1120 * We later require that vma->vm_flags == vm_flags,
1121 * so this tests vma->vm_flags & VM_SPECIAL, too.
1122 */
1123 if (vm_flags & VM_SPECIAL)
1124 return NULL;
1125
1126 if (prev)
1127 next = prev->vm_next;
1128 else
1129 next = mm->mmap;
1130 area = next;
1131 if (area && area->vm_end == end) /* cases 6, 7, 8 */
1132 next = next->vm_next;
1133
1134 /* verify some invariant that must be enforced by the caller */
1135 VM_WARN_ON(prev && addr <= prev->vm_start);
1136 VM_WARN_ON(area && end > area->vm_end);
1137 VM_WARN_ON(addr >= end);
1138
1139 /*
1140 * Can it merge with the predecessor?
1141 */
1142 if (prev && prev->vm_end == addr &&
1143 mpol_equal(vma_policy(prev), policy) &&
1144 can_vma_merge_after(prev, vm_flags,
1145 anon_vma, file, pgoff,
1146 vm_userfaultfd_ctx)) {
1147 /*
1148 * OK, it can. Can we now merge in the successor as well?
1149 */
1150 if (next && end == next->vm_start &&
1151 mpol_equal(policy, vma_policy(next)) &&
1152 can_vma_merge_before(next, vm_flags,
1153 anon_vma, file,
1154 pgoff+pglen,
1155 vm_userfaultfd_ctx) &&
1156 is_mergeable_anon_vma(prev->anon_vma,
1157 next->anon_vma, NULL)) {
1158 /* cases 1, 6 */
1159 err = __vma_adjust(prev, prev->vm_start,
1160 next->vm_end, prev->vm_pgoff, NULL,
1161 prev);
1162 } else /* cases 2, 5, 7 */
1163 err = __vma_adjust(prev, prev->vm_start,
1164 end, prev->vm_pgoff, NULL, prev);
1165 if (err)
1166 return NULL;
1167 khugepaged_enter_vma_merge(prev, vm_flags);
1168 return prev;
1169 }
1170
1171 /*
1172 * Can this new request be merged in front of next?
1173 */
1174 if (next && end == next->vm_start &&
1175 mpol_equal(policy, vma_policy(next)) &&
1176 can_vma_merge_before(next, vm_flags,
1177 anon_vma, file, pgoff+pglen,
1178 vm_userfaultfd_ctx)) {
1179 if (prev && addr < prev->vm_end) /* case 4 */
1180 err = __vma_adjust(prev, prev->vm_start,
1181 addr, prev->vm_pgoff, NULL, next);
1182 else { /* cases 3, 8 */
1183 err = __vma_adjust(area, addr, next->vm_end,
1184 next->vm_pgoff - pglen, NULL, next);
1185 /*
1186 * In case 3 area is already equal to next and
1187 * this is a noop, but in case 8 "area" has
1188 * been removed and next was expanded over it.
1189 */
1190 area = next;
1191 }
1192 if (err)
1193 return NULL;
1194 khugepaged_enter_vma_merge(area, vm_flags);
1195 return area;
1196 }
1197
1198 return NULL;
1199}
1200
1201/*
1202 * Rough compatbility check to quickly see if it's even worth looking
1203 * at sharing an anon_vma.
1204 *
1205 * They need to have the same vm_file, and the flags can only differ
1206 * in things that mprotect may change.
1207 *
1208 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1209 * we can merge the two vma's. For example, we refuse to merge a vma if
1210 * there is a vm_ops->close() function, because that indicates that the
1211 * driver is doing some kind of reference counting. But that doesn't
1212 * really matter for the anon_vma sharing case.
1213 */
1214static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1215{
1216 return a->vm_end == b->vm_start &&
1217 mpol_equal(vma_policy(a), vma_policy(b)) &&
1218 a->vm_file == b->vm_file &&
1219 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) &&
1220 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1221}
1222
1223/*
1224 * Do some basic sanity checking to see if we can re-use the anon_vma
1225 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1226 * the same as 'old', the other will be the new one that is trying
1227 * to share the anon_vma.
1228 *
1229 * NOTE! This runs with mm_sem held for reading, so it is possible that
1230 * the anon_vma of 'old' is concurrently in the process of being set up
1231 * by another page fault trying to merge _that_. But that's ok: if it
1232 * is being set up, that automatically means that it will be a singleton
1233 * acceptable for merging, so we can do all of this optimistically. But
1234 * we do that READ_ONCE() to make sure that we never re-load the pointer.
1235 *
1236 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1237 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1238 * is to return an anon_vma that is "complex" due to having gone through
1239 * a fork).
1240 *
1241 * We also make sure that the two vma's are compatible (adjacent,
1242 * and with the same memory policies). That's all stable, even with just
1243 * a read lock on the mm_sem.
1244 */
1245static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1246{
1247 if (anon_vma_compatible(a, b)) {
1248 struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
1249
1250 if (anon_vma && list_is_singular(&old->anon_vma_chain))
1251 return anon_vma;
1252 }
1253 return NULL;
1254}
1255
1256/*
1257 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1258 * neighbouring vmas for a suitable anon_vma, before it goes off
1259 * to allocate a new anon_vma. It checks because a repetitive
1260 * sequence of mprotects and faults may otherwise lead to distinct
1261 * anon_vmas being allocated, preventing vma merge in subsequent
1262 * mprotect.
1263 */
1264struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1265{
1266 struct anon_vma *anon_vma;
1267 struct vm_area_struct *near;
1268
1269 near = vma->vm_next;
1270 if (!near)
1271 goto try_prev;
1272
1273 anon_vma = reusable_anon_vma(near, vma, near);
1274 if (anon_vma)
1275 return anon_vma;
1276try_prev:
1277 near = vma->vm_prev;
1278 if (!near)
1279 goto none;
1280
1281 anon_vma = reusable_anon_vma(near, near, vma);
1282 if (anon_vma)
1283 return anon_vma;
1284none:
1285 /*
1286 * There's no absolute need to look only at touching neighbours:
1287 * we could search further afield for "compatible" anon_vmas.
1288 * But it would probably just be a waste of time searching,
1289 * or lead to too many vmas hanging off the same anon_vma.
1290 * We're trying to allow mprotect remerging later on,
1291 * not trying to minimize memory used for anon_vmas.
1292 */
1293 return NULL;
1294}
1295
1296/*
1297 * If a hint addr is less than mmap_min_addr change hint to be as
1298 * low as possible but still greater than mmap_min_addr
1299 */
1300static inline unsigned long round_hint_to_min(unsigned long hint)
1301{
1302 hint &= PAGE_MASK;
1303 if (((void *)hint != NULL) &&
1304 (hint < mmap_min_addr))
1305 return PAGE_ALIGN(mmap_min_addr);
1306 return hint;
1307}
1308
1309static inline int mlock_future_check(struct mm_struct *mm,
1310 unsigned long flags,
1311 unsigned long len)
1312{
1313 unsigned long locked, lock_limit;
1314
1315 /* mlock MCL_FUTURE? */
1316 if (flags & VM_LOCKED) {
1317 locked = len >> PAGE_SHIFT;
1318 locked += mm->locked_vm;
1319 lock_limit = rlimit(RLIMIT_MEMLOCK);
1320 lock_limit >>= PAGE_SHIFT;
1321 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1322 return -EAGAIN;
1323 }
1324 return 0;
1325}
1326
1327static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
1328{
1329 if (S_ISREG(inode->i_mode))
1330 return MAX_LFS_FILESIZE;
1331
1332 if (S_ISBLK(inode->i_mode))
1333 return MAX_LFS_FILESIZE;
1334
1335 /* Special "we do even unsigned file positions" case */
1336 if (file->f_mode & FMODE_UNSIGNED_OFFSET)
1337 return 0;
1338
1339 /* Yes, random drivers might want more. But I'm tired of buggy drivers */
1340 return ULONG_MAX;
1341}
1342
1343static inline bool file_mmap_ok(struct file *file, struct inode *inode,
1344 unsigned long pgoff, unsigned long len)
1345{
1346 u64 maxsize = file_mmap_size_max(file, inode);
1347
1348 if (maxsize && len > maxsize)
1349 return false;
1350 maxsize -= len;
1351 if (pgoff > maxsize >> PAGE_SHIFT)
1352 return false;
1353 return true;
1354}
1355
1356/*
1357 * The caller must hold down_write(¤t->mm->mmap_sem).
1358 */
1359unsigned long do_mmap(struct file *file, unsigned long addr,
1360 unsigned long len, unsigned long prot,
1361 unsigned long flags, vm_flags_t vm_flags,
1362 unsigned long pgoff, unsigned long *populate,
1363 struct list_head *uf)
1364{
1365 struct mm_struct *mm = current->mm;
1366 int pkey = 0;
1367
1368 *populate = 0;
1369
1370 if (!len)
1371 return -EINVAL;
1372
1373 /*
1374 * Does the application expect PROT_READ to imply PROT_EXEC?
1375 *
1376 * (the exception is when the underlying filesystem is noexec
1377 * mounted, in which case we dont add PROT_EXEC.)
1378 */
1379 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1380 if (!(file && path_noexec(&file->f_path)))
1381 prot |= PROT_EXEC;
1382
1383 /* force arch specific MAP_FIXED handling in get_unmapped_area */
1384 if (flags & MAP_FIXED_NOREPLACE)
1385 flags |= MAP_FIXED;
1386
1387 if (!(flags & MAP_FIXED))
1388 addr = round_hint_to_min(addr);
1389
1390 /* Careful about overflows.. */
1391 len = PAGE_ALIGN(len);
1392 if (!len)
1393 return -ENOMEM;
1394
1395 /* offset overflow? */
1396 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1397 return -EOVERFLOW;
1398
1399 /* Too many mappings? */
1400 if (mm->map_count > sysctl_max_map_count)
1401 return -ENOMEM;
1402
1403 /* Obtain the address to map to. we verify (or select) it and ensure
1404 * that it represents a valid section of the address space.
1405 */
1406 addr = get_unmapped_area(file, addr, len, pgoff, flags);
1407 if (offset_in_page(addr))
1408 return addr;
1409
1410 if (flags & MAP_FIXED_NOREPLACE) {
1411 struct vm_area_struct *vma = find_vma(mm, addr);
1412
1413 if (vma && vma->vm_start <= addr)
1414 return -EEXIST;
1415 }
1416
1417 if (prot == PROT_EXEC) {
1418 pkey = execute_only_pkey(mm);
1419 if (pkey < 0)
1420 pkey = 0;
1421 }
1422
1423 /* Do simple checking here so the lower-level routines won't have
1424 * to. we assume access permissions have been handled by the open
1425 * of the memory object, so we don't do any here.
1426 */
1427 vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
1428 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1429
1430 if (flags & MAP_LOCKED)
1431 if (!can_do_mlock())
1432 return -EPERM;
1433
1434 if (mlock_future_check(mm, vm_flags, len))
1435 return -EAGAIN;
1436
1437 if (file) {
1438 struct inode *inode = file_inode(file);
1439 unsigned long flags_mask;
1440
1441 if (!file_mmap_ok(file, inode, pgoff, len))
1442 return -EOVERFLOW;
1443
1444 flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags;
1445
1446 switch (flags & MAP_TYPE) {
1447 case MAP_SHARED:
1448 /*
1449 * Force use of MAP_SHARED_VALIDATE with non-legacy
1450 * flags. E.g. MAP_SYNC is dangerous to use with
1451 * MAP_SHARED as you don't know which consistency model
1452 * you will get. We silently ignore unsupported flags
1453 * with MAP_SHARED to preserve backward compatibility.
1454 */
1455 flags &= LEGACY_MAP_MASK;
1456 /* fall through */
1457 case MAP_SHARED_VALIDATE:
1458 if (flags & ~flags_mask)
1459 return -EOPNOTSUPP;
1460 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1461 return -EACCES;
1462
1463 /*
1464 * Make sure we don't allow writing to an append-only
1465 * file..
1466 */
1467 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1468 return -EACCES;
1469
1470 /*
1471 * Make sure there are no mandatory locks on the file.
1472 */
1473 if (locks_verify_locked(file))
1474 return -EAGAIN;
1475
1476 vm_flags |= VM_SHARED | VM_MAYSHARE;
1477 if (!(file->f_mode & FMODE_WRITE))
1478 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1479
1480 /* fall through */
1481 case MAP_PRIVATE:
1482 if (!(file->f_mode & FMODE_READ))
1483 return -EACCES;
1484 if (path_noexec(&file->f_path)) {
1485 if (vm_flags & VM_EXEC)
1486 return -EPERM;
1487 vm_flags &= ~VM_MAYEXEC;
1488 }
1489
1490 if (!file->f_op->mmap)
1491 return -ENODEV;
1492 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1493 return -EINVAL;
1494 break;
1495
1496 default:
1497 return -EINVAL;
1498 }
1499 } else {
1500 switch (flags & MAP_TYPE) {
1501 case MAP_SHARED:
1502 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1503 return -EINVAL;
1504 /*
1505 * Ignore pgoff.
1506 */
1507 pgoff = 0;
1508 vm_flags |= VM_SHARED | VM_MAYSHARE;
1509 break;
1510 case MAP_PRIVATE:
1511 /*
1512 * Set pgoff according to addr for anon_vma.
1513 */
1514 pgoff = addr >> PAGE_SHIFT;
1515 break;
1516 default:
1517 return -EINVAL;
1518 }
1519 }
1520
1521 /*
1522 * Set 'VM_NORESERVE' if we should not account for the
1523 * memory use of this mapping.
1524 */
1525 if (flags & MAP_NORESERVE) {
1526 /* We honor MAP_NORESERVE if allowed to overcommit */
1527 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1528 vm_flags |= VM_NORESERVE;
1529
1530 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1531 if (file && is_file_hugepages(file))
1532 vm_flags |= VM_NORESERVE;
1533 }
1534
1535 addr = mmap_region(file, addr, len, vm_flags, pgoff, uf);
1536 if (!IS_ERR_VALUE(addr) &&
1537 ((vm_flags & VM_LOCKED) ||
1538 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1539 *populate = len;
1540 return addr;
1541}
1542
1543unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
1544 unsigned long prot, unsigned long flags,
1545 unsigned long fd, unsigned long pgoff)
1546{
1547 struct file *file = NULL;
1548 unsigned long retval;
1549
1550 if (!(flags & MAP_ANONYMOUS)) {
1551 audit_mmap_fd(fd, flags);
1552 file = fget(fd);
1553 if (!file)
1554 return -EBADF;
1555 if (is_file_hugepages(file))
1556 len = ALIGN(len, huge_page_size(hstate_file(file)));
1557 retval = -EINVAL;
1558 if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
1559 goto out_fput;
1560 } else if (flags & MAP_HUGETLB) {
1561 struct user_struct *user = NULL;
1562 struct hstate *hs;
1563
1564 hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1565 if (!hs)
1566 return -EINVAL;
1567
1568 len = ALIGN(len, huge_page_size(hs));
1569 /*
1570 * VM_NORESERVE is used because the reservations will be
1571 * taken when vm_ops->mmap() is called
1572 * A dummy user value is used because we are not locking
1573 * memory so no accounting is necessary
1574 */
1575 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1576 VM_NORESERVE,
1577 &user, HUGETLB_ANONHUGE_INODE,
1578 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1579 if (IS_ERR(file))
1580 return PTR_ERR(file);
1581 }
1582
1583 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1584
1585 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1586out_fput:
1587 if (file)
1588 fput(file);
1589 return retval;
1590}
1591
1592SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1593 unsigned long, prot, unsigned long, flags,
1594 unsigned long, fd, unsigned long, pgoff)
1595{
1596 return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff);
1597}
1598
1599#ifdef __ARCH_WANT_SYS_OLD_MMAP
1600struct mmap_arg_struct {
1601 unsigned long addr;
1602 unsigned long len;
1603 unsigned long prot;
1604 unsigned long flags;
1605 unsigned long fd;
1606 unsigned long offset;
1607};
1608
1609SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1610{
1611 struct mmap_arg_struct a;
1612
1613 if (copy_from_user(&a, arg, sizeof(a)))
1614 return -EFAULT;
1615 if (offset_in_page(a.offset))
1616 return -EINVAL;
1617
1618 return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1619 a.offset >> PAGE_SHIFT);
1620}
1621#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1622
1623/*
1624 * Some shared mappigns will want the pages marked read-only
1625 * to track write events. If so, we'll downgrade vm_page_prot
1626 * to the private version (using protection_map[] without the
1627 * VM_SHARED bit).
1628 */
1629int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot)
1630{
1631 vm_flags_t vm_flags = vma->vm_flags;
1632 const struct vm_operations_struct *vm_ops = vma->vm_ops;
1633
1634 /* If it was private or non-writable, the write bit is already clear */
1635 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1636 return 0;
1637
1638 /* The backer wishes to know when pages are first written to? */
1639 if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite))
1640 return 1;
1641
1642 /* The open routine did something to the protections that pgprot_modify
1643 * won't preserve? */
1644 if (pgprot_val(vm_page_prot) !=
1645 pgprot_val(vm_pgprot_modify(vm_page_prot, vm_flags)))
1646 return 0;
1647
1648 /* Do we need to track softdirty? */
1649 if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY))
1650 return 1;
1651
1652 /* Specialty mapping? */
1653 if (vm_flags & VM_PFNMAP)
1654 return 0;
1655
1656 /* Can the mapping track the dirty pages? */
1657 return vma->vm_file && vma->vm_file->f_mapping &&
1658 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1659}
1660
1661/*
1662 * We account for memory if it's a private writeable mapping,
1663 * not hugepages and VM_NORESERVE wasn't set.
1664 */
1665static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1666{
1667 /*
1668 * hugetlb has its own accounting separate from the core VM
1669 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1670 */
1671 if (file && is_file_hugepages(file))
1672 return 0;
1673
1674 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1675}
1676
1677unsigned long mmap_region(struct file *file, unsigned long addr,
1678 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
1679 struct list_head *uf)
1680{
1681 struct mm_struct *mm = current->mm;
1682 struct vm_area_struct *vma, *prev;
1683 int error;
1684 struct rb_node **rb_link, *rb_parent;
1685 unsigned long charged = 0;
1686
1687 /* Check against address space limit. */
1688 if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
1689 unsigned long nr_pages;
1690
1691 /*
1692 * MAP_FIXED may remove pages of mappings that intersects with
1693 * requested mapping. Account for the pages it would unmap.
1694 */
1695 nr_pages = count_vma_pages_range(mm, addr, addr + len);
1696
1697 if (!may_expand_vm(mm, vm_flags,
1698 (len >> PAGE_SHIFT) - nr_pages))
1699 return -ENOMEM;
1700 }
1701
1702 /* Clear old maps */
1703 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
1704 &rb_parent)) {
1705 if (do_munmap(mm, addr, len, uf))
1706 return -ENOMEM;
1707 }
1708
1709 /*
1710 * Private writable mapping: check memory availability
1711 */
1712 if (accountable_mapping(file, vm_flags)) {
1713 charged = len >> PAGE_SHIFT;
1714 if (security_vm_enough_memory_mm(mm, charged))
1715 return -ENOMEM;
1716 vm_flags |= VM_ACCOUNT;
1717 }
1718
1719 /*
1720 * Can we just expand an old mapping?
1721 */
1722 vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
1723 NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX);
1724 if (vma)
1725 goto out;
1726
1727 /*
1728 * Determine the object being mapped and call the appropriate
1729 * specific mapper. the address has already been validated, but
1730 * not unmapped, but the maps are removed from the list.
1731 */
1732 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1733 if (!vma) {
1734 error = -ENOMEM;
1735 goto unacct_error;
1736 }
1737
1738 vma->vm_mm = mm;
1739 vma->vm_start = addr;
1740 vma->vm_end = addr + len;
1741 vma->vm_flags = vm_flags;
1742 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1743 vma->vm_pgoff = pgoff;
1744 INIT_LIST_HEAD(&vma->anon_vma_chain);
1745
1746 if (file) {
1747 if (vm_flags & VM_DENYWRITE) {
1748 error = deny_write_access(file);
1749 if (error)
1750 goto free_vma;
1751 }
1752 if (vm_flags & VM_SHARED) {
1753 error = mapping_map_writable(file->f_mapping);
1754 if (error)
1755 goto allow_write_and_free_vma;
1756 }
1757
1758 /* ->mmap() can change vma->vm_file, but must guarantee that
1759 * vma_link() below can deny write-access if VM_DENYWRITE is set
1760 * and map writably if VM_SHARED is set. This usually means the
1761 * new file must not have been exposed to user-space, yet.
1762 */
1763 vma->vm_file = get_file(file);
1764 error = call_mmap(file, vma);
1765 if (error)
1766 goto unmap_and_free_vma;
1767
1768 /* Can addr have changed??
1769 *
1770 * Answer: Yes, several device drivers can do it in their
1771 * f_op->mmap method. -DaveM
1772 * Bug: If addr is changed, prev, rb_link, rb_parent should
1773 * be updated for vma_link()
1774 */
1775 WARN_ON_ONCE(addr != vma->vm_start);
1776
1777 addr = vma->vm_start;
1778 vm_flags = vma->vm_flags;
1779 } else if (vm_flags & VM_SHARED) {
1780 error = shmem_zero_setup(vma);
1781 if (error)
1782 goto free_vma;
1783 }
1784
1785 vma_link(mm, vma, prev, rb_link, rb_parent);
1786 /* Once vma denies write, undo our temporary denial count */
1787 if (file) {
1788 if (vm_flags & VM_SHARED)
1789 mapping_unmap_writable(file->f_mapping);
1790 if (vm_flags & VM_DENYWRITE)
1791 allow_write_access(file);
1792 }
1793 file = vma->vm_file;
1794out:
1795 perf_event_mmap(vma);
1796
1797 vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
1798 if (vm_flags & VM_LOCKED) {
1799 if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
1800 vma == get_gate_vma(current->mm)))
1801 mm->locked_vm += (len >> PAGE_SHIFT);
1802 else
1803 vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
1804 }
1805
1806 if (file)
1807 uprobe_mmap(vma);
1808
1809 /*
1810 * New (or expanded) vma always get soft dirty status.
1811 * Otherwise user-space soft-dirty page tracker won't
1812 * be able to distinguish situation when vma area unmapped,
1813 * then new mapped in-place (which must be aimed as
1814 * a completely new data area).
1815 */
1816 vma->vm_flags |= VM_SOFTDIRTY;
1817
1818 vma_set_page_prot(vma);
1819
1820 return addr;
1821
1822unmap_and_free_vma:
1823 vma->vm_file = NULL;
1824 fput(file);
1825
1826 /* Undo any partial mapping done by a device driver. */
1827 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1828 charged = 0;
1829 if (vm_flags & VM_SHARED)
1830 mapping_unmap_writable(file->f_mapping);
1831allow_write_and_free_vma:
1832 if (vm_flags & VM_DENYWRITE)
1833 allow_write_access(file);
1834free_vma:
1835 kmem_cache_free(vm_area_cachep, vma);
1836unacct_error:
1837 if (charged)
1838 vm_unacct_memory(charged);
1839 return error;
1840}
1841
1842unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1843{
1844 /*
1845 * We implement the search by looking for an rbtree node that
1846 * immediately follows a suitable gap. That is,
1847 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1848 * - gap_end = vma->vm_start >= info->low_limit + length;
1849 * - gap_end - gap_start >= length
1850 */
1851
1852 struct mm_struct *mm = current->mm;
1853 struct vm_area_struct *vma;
1854 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1855
1856 /* Adjust search length to account for worst case alignment overhead */
1857 length = info->length + info->align_mask;
1858 if (length < info->length)
1859 return -ENOMEM;
1860
1861 /* Adjust search limits by the desired length */
1862 if (info->high_limit < length)
1863 return -ENOMEM;
1864 high_limit = info->high_limit - length;
1865
1866 if (info->low_limit > high_limit)
1867 return -ENOMEM;
1868 low_limit = info->low_limit + length;
1869
1870 /* Check if rbtree root looks promising */
1871 if (RB_EMPTY_ROOT(&mm->mm_rb))
1872 goto check_highest;
1873 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1874 if (vma->rb_subtree_gap < length)
1875 goto check_highest;
1876
1877 while (true) {
1878 /* Visit left subtree if it looks promising */
1879 gap_end = vm_start_gap(vma);
1880 if (gap_end >= low_limit && vma->vm_rb.rb_left) {
1881 struct vm_area_struct *left =
1882 rb_entry(vma->vm_rb.rb_left,
1883 struct vm_area_struct, vm_rb);
1884 if (left->rb_subtree_gap >= length) {
1885 vma = left;
1886 continue;
1887 }
1888 }
1889
1890 gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
1891check_current:
1892 /* Check if current node has a suitable gap */
1893 if (gap_start > high_limit)
1894 return -ENOMEM;
1895 if (gap_end >= low_limit &&
1896 gap_end > gap_start && gap_end - gap_start >= length)
1897 goto found;
1898
1899 /* Visit right subtree if it looks promising */
1900 if (vma->vm_rb.rb_right) {
1901 struct vm_area_struct *right =
1902 rb_entry(vma->vm_rb.rb_right,
1903 struct vm_area_struct, vm_rb);
1904 if (right->rb_subtree_gap >= length) {
1905 vma = right;
1906 continue;
1907 }
1908 }
1909
1910 /* Go back up the rbtree to find next candidate node */
1911 while (true) {
1912 struct rb_node *prev = &vma->vm_rb;
1913 if (!rb_parent(prev))
1914 goto check_highest;
1915 vma = rb_entry(rb_parent(prev),
1916 struct vm_area_struct, vm_rb);
1917 if (prev == vma->vm_rb.rb_left) {
1918 gap_start = vm_end_gap(vma->vm_prev);
1919 gap_end = vm_start_gap(vma);
1920 goto check_current;
1921 }
1922 }
1923 }
1924
1925check_highest:
1926 /* Check highest gap, which does not precede any rbtree node */
1927 gap_start = mm->highest_vm_end;
1928 gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */
1929 if (gap_start > high_limit)
1930 return -ENOMEM;
1931
1932found:
1933 /* We found a suitable gap. Clip it with the original low_limit. */
1934 if (gap_start < info->low_limit)
1935 gap_start = info->low_limit;
1936
1937 /* Adjust gap address to the desired alignment */
1938 gap_start += (info->align_offset - gap_start) & info->align_mask;
1939
1940 VM_BUG_ON(gap_start + info->length > info->high_limit);
1941 VM_BUG_ON(gap_start + info->length > gap_end);
1942 return gap_start;
1943}
1944
1945unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
1946{
1947 struct mm_struct *mm = current->mm;
1948 struct vm_area_struct *vma;
1949 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1950
1951 /* Adjust search length to account for worst case alignment overhead */
1952 length = info->length + info->align_mask;
1953 if (length < info->length)
1954 return -ENOMEM;
1955
1956 /*
1957 * Adjust search limits by the desired length.
1958 * See implementation comment at top of unmapped_area().
1959 */
1960 gap_end = info->high_limit;
1961 if (gap_end < length)
1962 return -ENOMEM;
1963 high_limit = gap_end - length;
1964
1965 if (info->low_limit > high_limit)
1966 return -ENOMEM;
1967 low_limit = info->low_limit + length;
1968
1969 /* Check highest gap, which does not precede any rbtree node */
1970 gap_start = mm->highest_vm_end;
1971 if (gap_start <= high_limit)
1972 goto found_highest;
1973
1974 /* Check if rbtree root looks promising */
1975 if (RB_EMPTY_ROOT(&mm->mm_rb))
1976 return -ENOMEM;
1977 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1978 if (vma->rb_subtree_gap < length)
1979 return -ENOMEM;
1980
1981 while (true) {
1982 /* Visit right subtree if it looks promising */
1983 gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
1984 if (gap_start <= high_limit && vma->vm_rb.rb_right) {
1985 struct vm_area_struct *right =
1986 rb_entry(vma->vm_rb.rb_right,
1987 struct vm_area_struct, vm_rb);
1988 if (right->rb_subtree_gap >= length) {
1989 vma = right;
1990 continue;
1991 }
1992 }
1993
1994check_current:
1995 /* Check if current node has a suitable gap */
1996 gap_end = vm_start_gap(vma);
1997 if (gap_end < low_limit)
1998 return -ENOMEM;
1999 if (gap_start <= high_limit &&
2000 gap_end > gap_start && gap_end - gap_start >= length)
2001 goto found;
2002
2003 /* Visit left subtree if it looks promising */
2004 if (vma->vm_rb.rb_left) {
2005 struct vm_area_struct *left =
2006 rb_entry(vma->vm_rb.rb_left,
2007 struct vm_area_struct, vm_rb);
2008 if (left->rb_subtree_gap >= length) {
2009 vma = left;
2010 continue;
2011 }
2012 }
2013
2014 /* Go back up the rbtree to find next candidate node */
2015 while (true) {
2016 struct rb_node *prev = &vma->vm_rb;
2017 if (!rb_parent(prev))
2018 return -ENOMEM;
2019 vma = rb_entry(rb_parent(prev),
2020 struct vm_area_struct, vm_rb);
2021 if (prev == vma->vm_rb.rb_right) {
2022 gap_start = vma->vm_prev ?
2023 vm_end_gap(vma->vm_prev) : 0;
2024 goto check_current;
2025 }
2026 }
2027 }
2028
2029found:
2030 /* We found a suitable gap. Clip it with the original high_limit. */
2031 if (gap_end > info->high_limit)
2032 gap_end = info->high_limit;
2033
2034found_highest:
2035 /* Compute highest gap address at the desired alignment */
2036 gap_end -= info->length;
2037 gap_end -= (gap_end - info->align_offset) & info->align_mask;
2038
2039 VM_BUG_ON(gap_end < info->low_limit);
2040 VM_BUG_ON(gap_end < gap_start);
2041 return gap_end;
2042}
2043
2044/* Get an address range which is currently unmapped.
2045 * For shmat() with addr=0.
2046 *
2047 * Ugly calling convention alert:
2048 * Return value with the low bits set means error value,
2049 * ie
2050 * if (ret & ~PAGE_MASK)
2051 * error = ret;
2052 *
2053 * This function "knows" that -ENOMEM has the bits set.
2054 */
2055#ifndef HAVE_ARCH_UNMAPPED_AREA
2056unsigned long
2057arch_get_unmapped_area(struct file *filp, unsigned long addr,
2058 unsigned long len, unsigned long pgoff, unsigned long flags)
2059{
2060 struct mm_struct *mm = current->mm;
2061 struct vm_area_struct *vma, *prev;
2062 struct vm_unmapped_area_info info;
2063
2064 if (len > TASK_SIZE - mmap_min_addr)
2065 return -ENOMEM;
2066
2067 if (flags & MAP_FIXED)
2068 return addr;
2069
2070 if (addr) {
2071 addr = PAGE_ALIGN(addr);
2072 vma = find_vma_prev(mm, addr, &prev);
2073 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
2074 (!vma || addr + len <= vm_start_gap(vma)) &&
2075 (!prev || addr >= vm_end_gap(prev)))
2076 return addr;
2077 }
2078
2079 info.flags = 0;
2080 info.length = len;
2081 info.low_limit = mm->mmap_base;
2082 info.high_limit = TASK_SIZE;
2083 info.align_mask = 0;
2084 return vm_unmapped_area(&info);
2085}
2086#endif
2087
2088/*
2089 * This mmap-allocator allocates new areas top-down from below the
2090 * stack's low limit (the base):
2091 */
2092#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
2093unsigned long
2094arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
2095 const unsigned long len, const unsigned long pgoff,
2096 const unsigned long flags)
2097{
2098 struct vm_area_struct *vma, *prev;
2099 struct mm_struct *mm = current->mm;
2100 unsigned long addr = addr0;
2101 struct vm_unmapped_area_info info;
2102
2103 /* requested length too big for entire address space */
2104 if (len > TASK_SIZE - mmap_min_addr)
2105 return -ENOMEM;
2106
2107 if (flags & MAP_FIXED)
2108 return addr;
2109
2110 /* requesting a specific address */
2111 if (addr) {
2112 addr = PAGE_ALIGN(addr);
2113 vma = find_vma_prev(mm, addr, &prev);
2114 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
2115 (!vma || addr + len <= vm_start_gap(vma)) &&
2116 (!prev || addr >= vm_end_gap(prev)))
2117 return addr;
2118 }
2119
2120 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
2121 info.length = len;
2122 info.low_limit = max(PAGE_SIZE, mmap_min_addr);
2123 info.high_limit = mm->mmap_base;
2124 info.align_mask = 0;
2125 addr = vm_unmapped_area(&info);
2126
2127 /*
2128 * A failed mmap() very likely causes application failure,
2129 * so fall back to the bottom-up function here. This scenario
2130 * can happen with large stack limits and large mmap()
2131 * allocations.
2132 */
2133 if (offset_in_page(addr)) {
2134 VM_BUG_ON(addr != -ENOMEM);
2135 info.flags = 0;
2136 info.low_limit = TASK_UNMAPPED_BASE;
2137 info.high_limit = TASK_SIZE;
2138 addr = vm_unmapped_area(&info);
2139 }
2140
2141 return addr;
2142}
2143#endif
2144
2145unsigned long
2146get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
2147 unsigned long pgoff, unsigned long flags)
2148{
2149 unsigned long (*get_area)(struct file *, unsigned long,
2150 unsigned long, unsigned long, unsigned long);
2151
2152 unsigned long error = arch_mmap_check(addr, len, flags);
2153 if (error)
2154 return error;
2155
2156 /* Careful about overflows.. */
2157 if (len > TASK_SIZE)
2158 return -ENOMEM;
2159
2160 get_area = current->mm->get_unmapped_area;
2161 if (file) {
2162 if (file->f_op->get_unmapped_area)
2163 get_area = file->f_op->get_unmapped_area;
2164 } else if (flags & MAP_SHARED) {
2165 /*
2166 * mmap_region() will call shmem_zero_setup() to create a file,
2167 * so use shmem's get_unmapped_area in case it can be huge.
2168 * do_mmap_pgoff() will clear pgoff, so match alignment.
2169 */
2170 pgoff = 0;
2171 get_area = shmem_get_unmapped_area;
2172 }
2173
2174 addr = get_area(file, addr, len, pgoff, flags);
2175 if (IS_ERR_VALUE(addr))
2176 return addr;
2177
2178 if (addr > TASK_SIZE - len)
2179 return -ENOMEM;
2180 if (offset_in_page(addr))
2181 return -EINVAL;
2182
2183 error = security_mmap_addr(addr);
2184 return error ? error : addr;
2185}
2186
2187EXPORT_SYMBOL(get_unmapped_area);
2188
2189/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
2190struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
2191{
2192 struct rb_node *rb_node;
2193 struct vm_area_struct *vma;
2194
2195 /* Check the cache first. */
2196 vma = vmacache_find(mm, addr);
2197 if (likely(vma))
2198 return vma;
2199
2200 rb_node = mm->mm_rb.rb_node;
2201
2202 while (rb_node) {
2203 struct vm_area_struct *tmp;
2204
2205 tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2206
2207 if (tmp->vm_end > addr) {
2208 vma = tmp;
2209 if (tmp->vm_start <= addr)
2210 break;
2211 rb_node = rb_node->rb_left;
2212 } else
2213 rb_node = rb_node->rb_right;
2214 }
2215
2216 if (vma)
2217 vmacache_update(addr, vma);
2218 return vma;
2219}
2220
2221EXPORT_SYMBOL(find_vma);
2222
2223/*
2224 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
2225 */
2226struct vm_area_struct *
2227find_vma_prev(struct mm_struct *mm, unsigned long addr,
2228 struct vm_area_struct **pprev)
2229{
2230 struct vm_area_struct *vma;
2231
2232 vma = find_vma(mm, addr);
2233 if (vma) {
2234 *pprev = vma->vm_prev;
2235 } else {
2236 struct rb_node *rb_node = mm->mm_rb.rb_node;
2237 *pprev = NULL;
2238 while (rb_node) {
2239 *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2240 rb_node = rb_node->rb_right;
2241 }
2242 }
2243 return vma;
2244}
2245
2246/*
2247 * Verify that the stack growth is acceptable and
2248 * update accounting. This is shared with both the
2249 * grow-up and grow-down cases.
2250 */
2251static int acct_stack_growth(struct vm_area_struct *vma,
2252 unsigned long size, unsigned long grow)
2253{
2254 struct mm_struct *mm = vma->vm_mm;
2255 unsigned long new_start;
2256
2257 /* address space limit tests */
2258 if (!may_expand_vm(mm, vma->vm_flags, grow))
2259 return -ENOMEM;
2260
2261 /* Stack limit test */
2262 if (size > rlimit(RLIMIT_STACK))
2263 return -ENOMEM;
2264
2265 /* mlock limit tests */
2266 if (vma->vm_flags & VM_LOCKED) {
2267 unsigned long locked;
2268 unsigned long limit;
2269 locked = mm->locked_vm + grow;
2270 limit = rlimit(RLIMIT_MEMLOCK);
2271 limit >>= PAGE_SHIFT;
2272 if (locked > limit && !capable(CAP_IPC_LOCK))
2273 return -ENOMEM;
2274 }
2275
2276 /* Check to ensure the stack will not grow into a hugetlb-only region */
2277 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
2278 vma->vm_end - size;
2279 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
2280 return -EFAULT;
2281
2282 /*
2283 * Overcommit.. This must be the final test, as it will
2284 * update security statistics.
2285 */
2286 if (security_vm_enough_memory_mm(mm, grow))
2287 return -ENOMEM;
2288
2289 return 0;
2290}
2291
2292#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2293/*
2294 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2295 * vma is the last one with address > vma->vm_end. Have to extend vma.
2296 */
2297int expand_upwards(struct vm_area_struct *vma, unsigned long address)
2298{
2299 struct mm_struct *mm = vma->vm_mm;
2300 struct vm_area_struct *next;
2301 unsigned long gap_addr;
2302 int error = 0;
2303
2304 if (!(vma->vm_flags & VM_GROWSUP))
2305 return -EFAULT;
2306
2307 /* Guard against exceeding limits of the address space. */
2308 address &= PAGE_MASK;
2309 if (address >= (TASK_SIZE & PAGE_MASK))
2310 return -ENOMEM;
2311 address += PAGE_SIZE;
2312
2313 /* Enforce stack_guard_gap */
2314 gap_addr = address + stack_guard_gap;
2315
2316 /* Guard against overflow */
2317 if (gap_addr < address || gap_addr > TASK_SIZE)
2318 gap_addr = TASK_SIZE;
2319
2320 next = vma->vm_next;
2321 if (next && next->vm_start < gap_addr &&
2322 (next->vm_flags & (VM_WRITE|VM_READ|VM_EXEC))) {
2323 if (!(next->vm_flags & VM_GROWSUP))
2324 return -ENOMEM;
2325 /* Check that both stack segments have the same anon_vma? */
2326 }
2327
2328 /* We must make sure the anon_vma is allocated. */
2329 if (unlikely(anon_vma_prepare(vma)))
2330 return -ENOMEM;
2331
2332 /*
2333 * vma->vm_start/vm_end cannot change under us because the caller
2334 * is required to hold the mmap_sem in read mode. We need the
2335 * anon_vma lock to serialize against concurrent expand_stacks.
2336 */
2337 anon_vma_lock_write(vma->anon_vma);
2338
2339 /* Somebody else might have raced and expanded it already */
2340 if (address > vma->vm_end) {
2341 unsigned long size, grow;
2342
2343 size = address - vma->vm_start;
2344 grow = (address - vma->vm_end) >> PAGE_SHIFT;
2345
2346 error = -ENOMEM;
2347 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2348 error = acct_stack_growth(vma, size, grow);
2349 if (!error) {
2350 /*
2351 * vma_gap_update() doesn't support concurrent
2352 * updates, but we only hold a shared mmap_sem
2353 * lock here, so we need to protect against
2354 * concurrent vma expansions.
2355 * anon_vma_lock_write() doesn't help here, as
2356 * we don't guarantee that all growable vmas
2357 * in a mm share the same root anon vma.
2358 * So, we reuse mm->page_table_lock to guard
2359 * against concurrent vma expansions.
2360 */
2361 spin_lock(&mm->page_table_lock);
2362 if (vma->vm_flags & VM_LOCKED)
2363 mm->locked_vm += grow;
2364 vm_stat_account(mm, vma->vm_flags, grow);
2365 anon_vma_interval_tree_pre_update_vma(vma);
2366 vma->vm_end = address;
2367 anon_vma_interval_tree_post_update_vma(vma);
2368 if (vma->vm_next)
2369 vma_gap_update(vma->vm_next);
2370 else
2371 mm->highest_vm_end = vm_end_gap(vma);
2372 spin_unlock(&mm->page_table_lock);
2373
2374 perf_event_mmap(vma);
2375 }
2376 }
2377 }
2378 anon_vma_unlock_write(vma->anon_vma);
2379 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2380 validate_mm(mm);
2381 return error;
2382}
2383#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2384
2385/*
2386 * vma is the first one with address < vma->vm_start. Have to extend vma.
2387 */
2388int expand_downwards(struct vm_area_struct *vma,
2389 unsigned long address)
2390{
2391 struct mm_struct *mm = vma->vm_mm;
2392 struct vm_area_struct *prev;
2393 int error;
2394
2395 address &= PAGE_MASK;
2396 error = security_mmap_addr(address);
2397 if (error)
2398 return error;
2399
2400 /* Enforce stack_guard_gap */
2401 prev = vma->vm_prev;
2402 /* Check that both stack segments have the same anon_vma? */
2403 if (prev && !(prev->vm_flags & VM_GROWSDOWN) &&
2404 (prev->vm_flags & (VM_WRITE|VM_READ|VM_EXEC))) {
2405 if (address - prev->vm_end < stack_guard_gap)
2406 return -ENOMEM;
2407 }
2408
2409 /* We must make sure the anon_vma is allocated. */
2410 if (unlikely(anon_vma_prepare(vma)))
2411 return -ENOMEM;
2412
2413 /*
2414 * vma->vm_start/vm_end cannot change under us because the caller
2415 * is required to hold the mmap_sem in read mode. We need the
2416 * anon_vma lock to serialize against concurrent expand_stacks.
2417 */
2418 anon_vma_lock_write(vma->anon_vma);
2419
2420 /* Somebody else might have raced and expanded it already */
2421 if (address < vma->vm_start) {
2422 unsigned long size, grow;
2423
2424 size = vma->vm_end - address;
2425 grow = (vma->vm_start - address) >> PAGE_SHIFT;
2426
2427 error = -ENOMEM;
2428 if (grow <= vma->vm_pgoff) {
2429 error = acct_stack_growth(vma, size, grow);
2430 if (!error) {
2431 /*
2432 * vma_gap_update() doesn't support concurrent
2433 * updates, but we only hold a shared mmap_sem
2434 * lock here, so we need to protect against
2435 * concurrent vma expansions.
2436 * anon_vma_lock_write() doesn't help here, as
2437 * we don't guarantee that all growable vmas
2438 * in a mm share the same root anon vma.
2439 * So, we reuse mm->page_table_lock to guard
2440 * against concurrent vma expansions.
2441 */
2442 spin_lock(&mm->page_table_lock);
2443 if (vma->vm_flags & VM_LOCKED)
2444 mm->locked_vm += grow;
2445 vm_stat_account(mm, vma->vm_flags, grow);
2446 anon_vma_interval_tree_pre_update_vma(vma);
2447 vma->vm_start = address;
2448 vma->vm_pgoff -= grow;
2449 anon_vma_interval_tree_post_update_vma(vma);
2450 vma_gap_update(vma);
2451 spin_unlock(&mm->page_table_lock);
2452
2453 perf_event_mmap(vma);
2454 }
2455 }
2456 }
2457 anon_vma_unlock_write(vma->anon_vma);
2458 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2459 validate_mm(mm);
2460 return error;
2461}
2462
2463/* enforced gap between the expanding stack and other mappings. */
2464unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
2465
2466static int __init cmdline_parse_stack_guard_gap(char *p)
2467{
2468 unsigned long val;
2469 char *endptr;
2470
2471 val = simple_strtoul(p, &endptr, 10);
2472 if (!*endptr)
2473 stack_guard_gap = val << PAGE_SHIFT;
2474
2475 return 0;
2476}
2477__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
2478
2479#ifdef CONFIG_STACK_GROWSUP
2480int expand_stack(struct vm_area_struct *vma, unsigned long address)
2481{
2482 return expand_upwards(vma, address);
2483}
2484
2485struct vm_area_struct *
2486find_extend_vma(struct mm_struct *mm, unsigned long addr)
2487{
2488 struct vm_area_struct *vma, *prev;
2489
2490 addr &= PAGE_MASK;
2491 vma = find_vma_prev(mm, addr, &prev);
2492 if (vma && (vma->vm_start <= addr))
2493 return vma;
2494 if (!prev || expand_stack(prev, addr))
2495 return NULL;
2496 if (prev->vm_flags & VM_LOCKED)
2497 populate_vma_page_range(prev, addr, prev->vm_end, NULL);
2498 return prev;
2499}
2500#else
2501int expand_stack(struct vm_area_struct *vma, unsigned long address)
2502{
2503 return expand_downwards(vma, address);
2504}
2505
2506struct vm_area_struct *
2507find_extend_vma(struct mm_struct *mm, unsigned long addr)
2508{
2509 struct vm_area_struct *vma;
2510 unsigned long start;
2511
2512 addr &= PAGE_MASK;
2513 vma = find_vma(mm, addr);
2514 if (!vma)
2515 return NULL;
2516 if (vma->vm_start <= addr)
2517 return vma;
2518 if (!(vma->vm_flags & VM_GROWSDOWN))
2519 return NULL;
2520 start = vma->vm_start;
2521 if (expand_stack(vma, addr))
2522 return NULL;
2523 if (vma->vm_flags & VM_LOCKED)
2524 populate_vma_page_range(vma, addr, start, NULL);
2525 return vma;
2526}
2527#endif
2528
2529EXPORT_SYMBOL_GPL(find_extend_vma);
2530
2531/*
2532 * Ok - we have the memory areas we should free on the vma list,
2533 * so release them, and do the vma updates.
2534 *
2535 * Called with the mm semaphore held.
2536 */
2537static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
2538{
2539 unsigned long nr_accounted = 0;
2540
2541 /* Update high watermark before we lower total_vm */
2542 update_hiwater_vm(mm);
2543 do {
2544 long nrpages = vma_pages(vma);
2545
2546 if (vma->vm_flags & VM_ACCOUNT)
2547 nr_accounted += nrpages;
2548 vm_stat_account(mm, vma->vm_flags, -nrpages);
2549 vma = remove_vma(vma);
2550 } while (vma);
2551 vm_unacct_memory(nr_accounted);
2552 validate_mm(mm);
2553}
2554
2555/*
2556 * Get rid of page table information in the indicated region.
2557 *
2558 * Called with the mm semaphore held.
2559 */
2560static void unmap_region(struct mm_struct *mm,
2561 struct vm_area_struct *vma, struct vm_area_struct *prev,
2562 unsigned long start, unsigned long end)
2563{
2564 struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap;
2565 struct mmu_gather tlb;
2566
2567 lru_add_drain();
2568 tlb_gather_mmu(&tlb, mm, start, end);
2569 update_hiwater_rss(mm);
2570 unmap_vmas(&tlb, vma, start, end);
2571 free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2572 next ? next->vm_start : USER_PGTABLES_CEILING);
2573 tlb_finish_mmu(&tlb, start, end);
2574}
2575
2576/*
2577 * Create a list of vma's touched by the unmap, removing them from the mm's
2578 * vma list as we go..
2579 */
2580static void
2581detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
2582 struct vm_area_struct *prev, unsigned long end)
2583{
2584 struct vm_area_struct **insertion_point;
2585 struct vm_area_struct *tail_vma = NULL;
2586
2587 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2588 vma->vm_prev = NULL;
2589 do {
2590 vma_rb_erase(vma, &mm->mm_rb);
2591 mm->map_count--;
2592 tail_vma = vma;
2593 vma = vma->vm_next;
2594 } while (vma && vma->vm_start < end);
2595 *insertion_point = vma;
2596 if (vma) {
2597 vma->vm_prev = prev;
2598 vma_gap_update(vma);
2599 } else
2600 mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
2601 tail_vma->vm_next = NULL;
2602
2603 /* Kill the cache */
2604 vmacache_invalidate(mm);
2605}
2606
2607/*
2608 * __split_vma() bypasses sysctl_max_map_count checking. We use this where it
2609 * has already been checked or doesn't make sense to fail.
2610 */
2611int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2612 unsigned long addr, int new_below)
2613{
2614 struct vm_area_struct *new;
2615 int err;
2616
2617 if (vma->vm_ops && vma->vm_ops->split) {
2618 err = vma->vm_ops->split(vma, addr);
2619 if (err)
2620 return err;
2621 }
2622
2623 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2624 if (!new)
2625 return -ENOMEM;
2626
2627 /* most fields are the same, copy all, and then fixup */
2628 *new = *vma;
2629
2630 INIT_LIST_HEAD(&new->anon_vma_chain);
2631
2632 if (new_below)
2633 new->vm_end = addr;
2634 else {
2635 new->vm_start = addr;
2636 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2637 }
2638
2639 err = vma_dup_policy(vma, new);
2640 if (err)
2641 goto out_free_vma;
2642
2643 err = anon_vma_clone(new, vma);
2644 if (err)
2645 goto out_free_mpol;
2646
2647 if (new->vm_file)
2648 get_file(new->vm_file);
2649
2650 if (new->vm_ops && new->vm_ops->open)
2651 new->vm_ops->open(new);
2652
2653 if (new_below)
2654 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2655 ((addr - new->vm_start) >> PAGE_SHIFT), new);
2656 else
2657 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2658
2659 /* Success. */
2660 if (!err)
2661 return 0;
2662
2663 /* Clean everything up if vma_adjust failed. */
2664 if (new->vm_ops && new->vm_ops->close)
2665 new->vm_ops->close(new);
2666 if (new->vm_file)
2667 fput(new->vm_file);
2668 unlink_anon_vmas(new);
2669 out_free_mpol:
2670 mpol_put(vma_policy(new));
2671 out_free_vma:
2672 kmem_cache_free(vm_area_cachep, new);
2673 return err;
2674}
2675
2676/*
2677 * Split a vma into two pieces at address 'addr', a new vma is allocated
2678 * either for the first part or the tail.
2679 */
2680int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2681 unsigned long addr, int new_below)
2682{
2683 if (mm->map_count >= sysctl_max_map_count)
2684 return -ENOMEM;
2685
2686 return __split_vma(mm, vma, addr, new_below);
2687}
2688
2689/* Munmap is split into 2 main parts -- this part which finds
2690 * what needs doing, and the areas themselves, which do the
2691 * work. This now handles partial unmappings.
2692 * Jeremy Fitzhardinge <jeremy@goop.org>
2693 */
2694int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
2695 struct list_head *uf)
2696{
2697 unsigned long end;
2698 struct vm_area_struct *vma, *prev, *last;
2699
2700 if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
2701 return -EINVAL;
2702
2703 len = PAGE_ALIGN(len);
2704 if (len == 0)
2705 return -EINVAL;
2706
2707 /* Find the first overlapping VMA */
2708 vma = find_vma(mm, start);
2709 if (!vma)
2710 return 0;
2711 prev = vma->vm_prev;
2712 /* we have start < vma->vm_end */
2713
2714 /* if it doesn't overlap, we have nothing.. */
2715 end = start + len;
2716 if (vma->vm_start >= end)
2717 return 0;
2718
2719 /*
2720 * If we need to split any vma, do it now to save pain later.
2721 *
2722 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2723 * unmapped vm_area_struct will remain in use: so lower split_vma
2724 * places tmp vma above, and higher split_vma places tmp vma below.
2725 */
2726 if (start > vma->vm_start) {
2727 int error;
2728
2729 /*
2730 * Make sure that map_count on return from munmap() will
2731 * not exceed its limit; but let map_count go just above
2732 * its limit temporarily, to help free resources as expected.
2733 */
2734 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2735 return -ENOMEM;
2736
2737 error = __split_vma(mm, vma, start, 0);
2738 if (error)
2739 return error;
2740 prev = vma;
2741 }
2742
2743 /* Does it split the last one? */
2744 last = find_vma(mm, end);
2745 if (last && end > last->vm_start) {
2746 int error = __split_vma(mm, last, end, 1);
2747 if (error)
2748 return error;
2749 }
2750 vma = prev ? prev->vm_next : mm->mmap;
2751
2752 if (unlikely(uf)) {
2753 /*
2754 * If userfaultfd_unmap_prep returns an error the vmas
2755 * will remain splitted, but userland will get a
2756 * highly unexpected error anyway. This is no
2757 * different than the case where the first of the two
2758 * __split_vma fails, but we don't undo the first
2759 * split, despite we could. This is unlikely enough
2760 * failure that it's not worth optimizing it for.
2761 */
2762 int error = userfaultfd_unmap_prep(vma, start, end, uf);
2763 if (error)
2764 return error;
2765 }
2766
2767 /*
2768 * unlock any mlock()ed ranges before detaching vmas
2769 */
2770 if (mm->locked_vm) {
2771 struct vm_area_struct *tmp = vma;
2772 while (tmp && tmp->vm_start < end) {
2773 if (tmp->vm_flags & VM_LOCKED) {
2774 mm->locked_vm -= vma_pages(tmp);
2775 munlock_vma_pages_all(tmp);
2776 }
2777 tmp = tmp->vm_next;
2778 }
2779 }
2780
2781 /*
2782 * Remove the vma's, and unmap the actual pages
2783 */
2784 detach_vmas_to_be_unmapped(mm, vma, prev, end);
2785 unmap_region(mm, vma, prev, start, end);
2786
2787 arch_unmap(mm, vma, start, end);
2788
2789 /* Fix up all other VM information */
2790 remove_vma_list(mm, vma);
2791
2792 return 0;
2793}
2794
2795int vm_munmap(unsigned long start, size_t len)
2796{
2797 int ret;
2798 struct mm_struct *mm = current->mm;
2799 LIST_HEAD(uf);
2800
2801 if (down_write_killable(&mm->mmap_sem))
2802 return -EINTR;
2803
2804 ret = do_munmap(mm, start, len, &uf);
2805 up_write(&mm->mmap_sem);
2806 userfaultfd_unmap_complete(mm, &uf);
2807 return ret;
2808}
2809EXPORT_SYMBOL(vm_munmap);
2810
2811SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2812{
2813 profile_munmap(addr);
2814 return vm_munmap(addr, len);
2815}
2816
2817
2818/*
2819 * Emulation of deprecated remap_file_pages() syscall.
2820 */
2821SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
2822 unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
2823{
2824
2825 struct mm_struct *mm = current->mm;
2826 struct vm_area_struct *vma;
2827 unsigned long populate = 0;
2828 unsigned long ret = -EINVAL;
2829 struct file *file;
2830
2831 pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.txt.\n",
2832 current->comm, current->pid);
2833
2834 if (prot)
2835 return ret;
2836 start = start & PAGE_MASK;
2837 size = size & PAGE_MASK;
2838
2839 if (start + size <= start)
2840 return ret;
2841
2842 /* Does pgoff wrap? */
2843 if (pgoff + (size >> PAGE_SHIFT) < pgoff)
2844 return ret;
2845
2846 if (down_write_killable(&mm->mmap_sem))
2847 return -EINTR;
2848
2849 vma = find_vma(mm, start);
2850
2851 if (!vma || !(vma->vm_flags & VM_SHARED))
2852 goto out;
2853
2854 if (start < vma->vm_start)
2855 goto out;
2856
2857 if (start + size > vma->vm_end) {
2858 struct vm_area_struct *next;
2859
2860 for (next = vma->vm_next; next; next = next->vm_next) {
2861 /* hole between vmas ? */
2862 if (next->vm_start != next->vm_prev->vm_end)
2863 goto out;
2864
2865 if (next->vm_file != vma->vm_file)
2866 goto out;
2867
2868 if (next->vm_flags != vma->vm_flags)
2869 goto out;
2870
2871 if (start + size <= next->vm_end)
2872 break;
2873 }
2874
2875 if (!next)
2876 goto out;
2877 }
2878
2879 prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
2880 prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
2881 prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
2882
2883 flags &= MAP_NONBLOCK;
2884 flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
2885 if (vma->vm_flags & VM_LOCKED) {
2886 struct vm_area_struct *tmp;
2887 flags |= MAP_LOCKED;
2888
2889 /* drop PG_Mlocked flag for over-mapped range */
2890 for (tmp = vma; tmp->vm_start >= start + size;
2891 tmp = tmp->vm_next) {
2892 /*
2893 * Split pmd and munlock page on the border
2894 * of the range.
2895 */
2896 vma_adjust_trans_huge(tmp, start, start + size, 0);
2897
2898 munlock_vma_pages_range(tmp,
2899 max(tmp->vm_start, start),
2900 min(tmp->vm_end, start + size));
2901 }
2902 }
2903
2904 file = get_file(vma->vm_file);
2905 ret = do_mmap_pgoff(vma->vm_file, start, size,
2906 prot, flags, pgoff, &populate, NULL);
2907 fput(file);
2908out:
2909 up_write(&mm->mmap_sem);
2910 if (populate)
2911 mm_populate(ret, populate);
2912 if (!IS_ERR_VALUE(ret))
2913 ret = 0;
2914 return ret;
2915}
2916
2917static inline void verify_mm_writelocked(struct mm_struct *mm)
2918{
2919#ifdef CONFIG_DEBUG_VM
2920 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2921 WARN_ON(1);
2922 up_read(&mm->mmap_sem);
2923 }
2924#endif
2925}
2926
2927/*
2928 * this is really a simplified "do_mmap". it only handles
2929 * anonymous maps. eventually we may be able to do some
2930 * brk-specific accounting here.
2931 */
2932static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long flags, struct list_head *uf)
2933{
2934 struct mm_struct *mm = current->mm;
2935 struct vm_area_struct *vma, *prev;
2936 unsigned long len;
2937 struct rb_node **rb_link, *rb_parent;
2938 pgoff_t pgoff = addr >> PAGE_SHIFT;
2939 int error;
2940
2941 len = PAGE_ALIGN(request);
2942 if (len < request)
2943 return -ENOMEM;
2944 if (!len)
2945 return 0;
2946
2947 /* Until we need other flags, refuse anything except VM_EXEC. */
2948 if ((flags & (~VM_EXEC)) != 0)
2949 return -EINVAL;
2950 flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2951
2952 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2953 if (offset_in_page(error))
2954 return error;
2955
2956 error = mlock_future_check(mm, mm->def_flags, len);
2957 if (error)
2958 return error;
2959
2960 /*
2961 * mm->mmap_sem is required to protect against another thread
2962 * changing the mappings in case we sleep.
2963 */
2964 verify_mm_writelocked(mm);
2965
2966 /*
2967 * Clear old maps. this also does some error checking for us
2968 */
2969 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
2970 &rb_parent)) {
2971 if (do_munmap(mm, addr, len, uf))
2972 return -ENOMEM;
2973 }
2974
2975 /* Check against address space limits *after* clearing old maps... */
2976 if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))
2977 return -ENOMEM;
2978
2979 if (mm->map_count > sysctl_max_map_count)
2980 return -ENOMEM;
2981
2982 if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
2983 return -ENOMEM;
2984
2985 /* Can we just expand an old private anonymous mapping? */
2986 vma = vma_merge(mm, prev, addr, addr + len, flags,
2987 NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX);
2988 if (vma)
2989 goto out;
2990
2991 /*
2992 * create a vma struct for an anonymous mapping
2993 */
2994 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2995 if (!vma) {
2996 vm_unacct_memory(len >> PAGE_SHIFT);
2997 return -ENOMEM;
2998 }
2999
3000 INIT_LIST_HEAD(&vma->anon_vma_chain);
3001 vma->vm_mm = mm;
3002 vma->vm_start = addr;
3003 vma->vm_end = addr + len;
3004 vma->vm_pgoff = pgoff;
3005 vma->vm_flags = flags;
3006 vma->vm_page_prot = vm_get_page_prot(flags);
3007 vma_link(mm, vma, prev, rb_link, rb_parent);
3008out:
3009 perf_event_mmap(vma);
3010 mm->total_vm += len >> PAGE_SHIFT;
3011 mm->data_vm += len >> PAGE_SHIFT;
3012 if (flags & VM_LOCKED)
3013 mm->locked_vm += (len >> PAGE_SHIFT);
3014 vma->vm_flags |= VM_SOFTDIRTY;
3015 return 0;
3016}
3017
3018static int do_brk(unsigned long addr, unsigned long len, struct list_head *uf)
3019{
3020 return do_brk_flags(addr, len, 0, uf);
3021}
3022
3023int vm_brk_flags(unsigned long addr, unsigned long len, unsigned long flags)
3024{
3025 struct mm_struct *mm = current->mm;
3026 int ret;
3027 bool populate;
3028 LIST_HEAD(uf);
3029
3030 if (down_write_killable(&mm->mmap_sem))
3031 return -EINTR;
3032
3033 ret = do_brk_flags(addr, len, flags, &uf);
3034 populate = ((mm->def_flags & VM_LOCKED) != 0);
3035 up_write(&mm->mmap_sem);
3036 userfaultfd_unmap_complete(mm, &uf);
3037 if (populate && !ret)
3038 mm_populate(addr, len);
3039 return ret;
3040}
3041EXPORT_SYMBOL(vm_brk_flags);
3042
3043int vm_brk(unsigned long addr, unsigned long len)
3044{
3045 return vm_brk_flags(addr, len, 0);
3046}
3047EXPORT_SYMBOL(vm_brk);
3048
3049/* Release all mmaps. */
3050void exit_mmap(struct mm_struct *mm)
3051{
3052 struct mmu_gather tlb;
3053 struct vm_area_struct *vma;
3054 unsigned long nr_accounted = 0;
3055
3056 /* mm's last user has gone, and its about to be pulled down */
3057 mmu_notifier_release(mm);
3058
3059 if (unlikely(mm_is_oom_victim(mm))) {
3060 /*
3061 * Manually reap the mm to free as much memory as possible.
3062 * Then, as the oom reaper does, set MMF_OOM_SKIP to disregard
3063 * this mm from further consideration. Taking mm->mmap_sem for
3064 * write after setting MMF_OOM_SKIP will guarantee that the oom
3065 * reaper will not run on this mm again after mmap_sem is
3066 * dropped.
3067 *
3068 * Nothing can be holding mm->mmap_sem here and the above call
3069 * to mmu_notifier_release(mm) ensures mmu notifier callbacks in
3070 * __oom_reap_task_mm() will not block.
3071 *
3072 * This needs to be done before calling munlock_vma_pages_all(),
3073 * which clears VM_LOCKED, otherwise the oom reaper cannot
3074 * reliably test it.
3075 */
3076 mutex_lock(&oom_lock);
3077 __oom_reap_task_mm(mm);
3078 mutex_unlock(&oom_lock);
3079
3080 set_bit(MMF_OOM_SKIP, &mm->flags);
3081 down_write(&mm->mmap_sem);
3082 up_write(&mm->mmap_sem);
3083 }
3084
3085 if (mm->locked_vm) {
3086 vma = mm->mmap;
3087 while (vma) {
3088 if (vma->vm_flags & VM_LOCKED)
3089 munlock_vma_pages_all(vma);
3090 vma = vma->vm_next;
3091 }
3092 }
3093
3094 arch_exit_mmap(mm);
3095
3096 vma = mm->mmap;
3097 if (!vma) /* Can happen if dup_mmap() received an OOM */
3098 return;
3099
3100 lru_add_drain();
3101 flush_cache_mm(mm);
3102 tlb_gather_mmu(&tlb, mm, 0, -1);
3103 /* update_hiwater_rss(mm) here? but nobody should be looking */
3104 /* Use -1 here to ensure all VMAs in the mm are unmapped */
3105 unmap_vmas(&tlb, vma, 0, -1);
3106 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
3107 tlb_finish_mmu(&tlb, 0, -1);
3108
3109 /*
3110 * Walk the list again, actually closing and freeing it,
3111 * with preemption enabled, without holding any MM locks.
3112 */
3113 while (vma) {
3114 if (vma->vm_flags & VM_ACCOUNT)
3115 nr_accounted += vma_pages(vma);
3116 vma = remove_vma(vma);
3117 }
3118 vm_unacct_memory(nr_accounted);
3119}
3120
3121/* Insert vm structure into process list sorted by address
3122 * and into the inode's i_mmap tree. If vm_file is non-NULL
3123 * then i_mmap_rwsem is taken here.
3124 */
3125int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
3126{
3127 struct vm_area_struct *prev;
3128 struct rb_node **rb_link, *rb_parent;
3129
3130 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
3131 &prev, &rb_link, &rb_parent))
3132 return -ENOMEM;
3133 if ((vma->vm_flags & VM_ACCOUNT) &&
3134 security_vm_enough_memory_mm(mm, vma_pages(vma)))
3135 return -ENOMEM;
3136
3137 /*
3138 * The vm_pgoff of a purely anonymous vma should be irrelevant
3139 * until its first write fault, when page's anon_vma and index
3140 * are set. But now set the vm_pgoff it will almost certainly
3141 * end up with (unless mremap moves it elsewhere before that
3142 * first wfault), so /proc/pid/maps tells a consistent story.
3143 *
3144 * By setting it to reflect the virtual start address of the
3145 * vma, merges and splits can happen in a seamless way, just
3146 * using the existing file pgoff checks and manipulations.
3147 * Similarly in do_mmap_pgoff and in do_brk.
3148 */
3149 if (vma_is_anonymous(vma)) {
3150 BUG_ON(vma->anon_vma);
3151 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
3152 }
3153
3154 vma_link(mm, vma, prev, rb_link, rb_parent);
3155 return 0;
3156}
3157
3158/*
3159 * Copy the vma structure to a new location in the same mm,
3160 * prior to moving page table entries, to effect an mremap move.
3161 */
3162struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
3163 unsigned long addr, unsigned long len, pgoff_t pgoff,
3164 bool *need_rmap_locks)
3165{
3166 struct vm_area_struct *vma = *vmap;
3167 unsigned long vma_start = vma->vm_start;
3168 struct mm_struct *mm = vma->vm_mm;
3169 struct vm_area_struct *new_vma, *prev;
3170 struct rb_node **rb_link, *rb_parent;
3171 bool faulted_in_anon_vma = true;
3172
3173 /*
3174 * If anonymous vma has not yet been faulted, update new pgoff
3175 * to match new location, to increase its chance of merging.
3176 */
3177 if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
3178 pgoff = addr >> PAGE_SHIFT;
3179 faulted_in_anon_vma = false;
3180 }
3181
3182 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
3183 return NULL; /* should never get here */
3184 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
3185 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
3186 vma->vm_userfaultfd_ctx);
3187 if (new_vma) {
3188 /*
3189 * Source vma may have been merged into new_vma
3190 */
3191 if (unlikely(vma_start >= new_vma->vm_start &&
3192 vma_start < new_vma->vm_end)) {
3193 /*
3194 * The only way we can get a vma_merge with
3195 * self during an mremap is if the vma hasn't
3196 * been faulted in yet and we were allowed to
3197 * reset the dst vma->vm_pgoff to the
3198 * destination address of the mremap to allow
3199 * the merge to happen. mremap must change the
3200 * vm_pgoff linearity between src and dst vmas
3201 * (in turn preventing a vma_merge) to be
3202 * safe. It is only safe to keep the vm_pgoff
3203 * linear if there are no pages mapped yet.
3204 */
3205 VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
3206 *vmap = vma = new_vma;
3207 }
3208 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
3209 } else {
3210 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
3211 if (!new_vma)
3212 goto out;
3213 *new_vma = *vma;
3214 new_vma->vm_start = addr;
3215 new_vma->vm_end = addr + len;
3216 new_vma->vm_pgoff = pgoff;
3217 if (vma_dup_policy(vma, new_vma))
3218 goto out_free_vma;
3219 INIT_LIST_HEAD(&new_vma->anon_vma_chain);
3220 if (anon_vma_clone(new_vma, vma))
3221 goto out_free_mempol;
3222 if (new_vma->vm_file)
3223 get_file(new_vma->vm_file);
3224 if (new_vma->vm_ops && new_vma->vm_ops->open)
3225 new_vma->vm_ops->open(new_vma);
3226 vma_link(mm, new_vma, prev, rb_link, rb_parent);
3227 *need_rmap_locks = false;
3228 }
3229 return new_vma;
3230
3231out_free_mempol:
3232 mpol_put(vma_policy(new_vma));
3233out_free_vma:
3234 kmem_cache_free(vm_area_cachep, new_vma);
3235out:
3236 return NULL;
3237}
3238
3239/*
3240 * Return true if the calling process may expand its vm space by the passed
3241 * number of pages
3242 */
3243bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
3244{
3245 if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
3246 return false;
3247
3248 if (is_data_mapping(flags) &&
3249 mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
3250 /* Workaround for Valgrind */
3251 if (rlimit(RLIMIT_DATA) == 0 &&
3252 mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
3253 return true;
3254
3255 pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n",
3256 current->comm, current->pid,
3257 (mm->data_vm + npages) << PAGE_SHIFT,
3258 rlimit(RLIMIT_DATA),
3259 ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data");
3260
3261 if (!ignore_rlimit_data)
3262 return false;
3263 }
3264
3265 return true;
3266}
3267
3268void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
3269{
3270 mm->total_vm += npages;
3271
3272 if (is_exec_mapping(flags))
3273 mm->exec_vm += npages;
3274 else if (is_stack_mapping(flags))
3275 mm->stack_vm += npages;
3276 else if (is_data_mapping(flags))
3277 mm->data_vm += npages;
3278}
3279
3280static int special_mapping_fault(struct vm_fault *vmf);
3281
3282/*
3283 * Having a close hook prevents vma merging regardless of flags.
3284 */
3285static void special_mapping_close(struct vm_area_struct *vma)
3286{
3287}
3288
3289static const char *special_mapping_name(struct vm_area_struct *vma)
3290{
3291 return ((struct vm_special_mapping *)vma->vm_private_data)->name;
3292}
3293
3294static int special_mapping_mremap(struct vm_area_struct *new_vma)
3295{
3296 struct vm_special_mapping *sm = new_vma->vm_private_data;
3297
3298 if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
3299 return -EFAULT;
3300
3301 if (sm->mremap)
3302 return sm->mremap(sm, new_vma);
3303
3304 return 0;
3305}
3306
3307static const struct vm_operations_struct special_mapping_vmops = {
3308 .close = special_mapping_close,
3309 .fault = special_mapping_fault,
3310 .mremap = special_mapping_mremap,
3311 .name = special_mapping_name,
3312};
3313
3314static const struct vm_operations_struct legacy_special_mapping_vmops = {
3315 .close = special_mapping_close,
3316 .fault = special_mapping_fault,
3317};
3318
3319static int special_mapping_fault(struct vm_fault *vmf)
3320{
3321 struct vm_area_struct *vma = vmf->vma;
3322 pgoff_t pgoff;
3323 struct page **pages;
3324
3325 if (vma->vm_ops == &legacy_special_mapping_vmops) {
3326 pages = vma->vm_private_data;
3327 } else {
3328 struct vm_special_mapping *sm = vma->vm_private_data;
3329
3330 if (sm->fault)
3331 return sm->fault(sm, vmf->vma, vmf);
3332
3333 pages = sm->pages;
3334 }
3335
3336 for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
3337 pgoff--;
3338
3339 if (*pages) {
3340 struct page *page = *pages;
3341 get_page(page);
3342 vmf->page = page;
3343 return 0;
3344 }
3345
3346 return VM_FAULT_SIGBUS;
3347}
3348
3349static struct vm_area_struct *__install_special_mapping(
3350 struct mm_struct *mm,
3351 unsigned long addr, unsigned long len,
3352 unsigned long vm_flags, void *priv,
3353 const struct vm_operations_struct *ops)
3354{
3355 int ret;
3356 struct vm_area_struct *vma;
3357
3358 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
3359 if (unlikely(vma == NULL))
3360 return ERR_PTR(-ENOMEM);
3361
3362 INIT_LIST_HEAD(&vma->anon_vma_chain);
3363 vma->vm_mm = mm;
3364 vma->vm_start = addr;
3365 vma->vm_end = addr + len;
3366
3367 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
3368 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
3369
3370 vma->vm_ops = ops;
3371 vma->vm_private_data = priv;
3372
3373 ret = insert_vm_struct(mm, vma);
3374 if (ret)
3375 goto out;
3376
3377 vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
3378
3379 perf_event_mmap(vma);
3380
3381 return vma;
3382
3383out:
3384 kmem_cache_free(vm_area_cachep, vma);
3385 return ERR_PTR(ret);
3386}
3387
3388bool vma_is_special_mapping(const struct vm_area_struct *vma,
3389 const struct vm_special_mapping *sm)
3390{
3391 return vma->vm_private_data == sm &&
3392 (vma->vm_ops == &special_mapping_vmops ||
3393 vma->vm_ops == &legacy_special_mapping_vmops);
3394}
3395
3396/*
3397 * Called with mm->mmap_sem held for writing.
3398 * Insert a new vma covering the given region, with the given flags.
3399 * Its pages are supplied by the given array of struct page *.
3400 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
3401 * The region past the last page supplied will always produce SIGBUS.
3402 * The array pointer and the pages it points to are assumed to stay alive
3403 * for as long as this mapping might exist.
3404 */
3405struct vm_area_struct *_install_special_mapping(
3406 struct mm_struct *mm,
3407 unsigned long addr, unsigned long len,
3408 unsigned long vm_flags, const struct vm_special_mapping *spec)
3409{
3410 return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
3411 &special_mapping_vmops);
3412}
3413
3414int install_special_mapping(struct mm_struct *mm,
3415 unsigned long addr, unsigned long len,
3416 unsigned long vm_flags, struct page **pages)
3417{
3418 struct vm_area_struct *vma = __install_special_mapping(
3419 mm, addr, len, vm_flags, (void *)pages,
3420 &legacy_special_mapping_vmops);
3421
3422 return PTR_ERR_OR_ZERO(vma);
3423}
3424
3425static DEFINE_MUTEX(mm_all_locks_mutex);
3426
3427static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
3428{
3429 if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
3430 /*
3431 * The LSB of head.next can't change from under us
3432 * because we hold the mm_all_locks_mutex.
3433 */
3434 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
3435 /*
3436 * We can safely modify head.next after taking the
3437 * anon_vma->root->rwsem. If some other vma in this mm shares
3438 * the same anon_vma we won't take it again.
3439 *
3440 * No need of atomic instructions here, head.next
3441 * can't change from under us thanks to the
3442 * anon_vma->root->rwsem.
3443 */
3444 if (__test_and_set_bit(0, (unsigned long *)
3445 &anon_vma->root->rb_root.rb_root.rb_node))
3446 BUG();
3447 }
3448}
3449
3450static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
3451{
3452 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3453 /*
3454 * AS_MM_ALL_LOCKS can't change from under us because
3455 * we hold the mm_all_locks_mutex.
3456 *
3457 * Operations on ->flags have to be atomic because
3458 * even if AS_MM_ALL_LOCKS is stable thanks to the
3459 * mm_all_locks_mutex, there may be other cpus
3460 * changing other bitflags in parallel to us.
3461 */
3462 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
3463 BUG();
3464 down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem);
3465 }
3466}
3467
3468/*
3469 * This operation locks against the VM for all pte/vma/mm related
3470 * operations that could ever happen on a certain mm. This includes
3471 * vmtruncate, try_to_unmap, and all page faults.
3472 *
3473 * The caller must take the mmap_sem in write mode before calling
3474 * mm_take_all_locks(). The caller isn't allowed to release the
3475 * mmap_sem until mm_drop_all_locks() returns.
3476 *
3477 * mmap_sem in write mode is required in order to block all operations
3478 * that could modify pagetables and free pages without need of
3479 * altering the vma layout. It's also needed in write mode to avoid new
3480 * anon_vmas to be associated with existing vmas.
3481 *
3482 * A single task can't take more than one mm_take_all_locks() in a row
3483 * or it would deadlock.
3484 *
3485 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3486 * mapping->flags avoid to take the same lock twice, if more than one
3487 * vma in this mm is backed by the same anon_vma or address_space.
3488 *
3489 * We take locks in following order, accordingly to comment at beginning
3490 * of mm/rmap.c:
3491 * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
3492 * hugetlb mapping);
3493 * - all i_mmap_rwsem locks;
3494 * - all anon_vma->rwseml
3495 *
3496 * We can take all locks within these types randomly because the VM code
3497 * doesn't nest them and we protected from parallel mm_take_all_locks() by
3498 * mm_all_locks_mutex.
3499 *
3500 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3501 * that may have to take thousand of locks.
3502 *
3503 * mm_take_all_locks() can fail if it's interrupted by signals.
3504 */
3505int mm_take_all_locks(struct mm_struct *mm)
3506{
3507 struct vm_area_struct *vma;
3508 struct anon_vma_chain *avc;
3509
3510 BUG_ON(down_read_trylock(&mm->mmap_sem));
3511
3512 mutex_lock(&mm_all_locks_mutex);
3513
3514 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3515 if (signal_pending(current))
3516 goto out_unlock;
3517 if (vma->vm_file && vma->vm_file->f_mapping &&
3518 is_vm_hugetlb_page(vma))
3519 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3520 }
3521
3522 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3523 if (signal_pending(current))
3524 goto out_unlock;
3525 if (vma->vm_file && vma->vm_file->f_mapping &&
3526 !is_vm_hugetlb_page(vma))
3527 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3528 }
3529
3530 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3531 if (signal_pending(current))
3532 goto out_unlock;
3533 if (vma->anon_vma)
3534 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3535 vm_lock_anon_vma(mm, avc->anon_vma);
3536 }
3537
3538 return 0;
3539
3540out_unlock:
3541 mm_drop_all_locks(mm);
3542 return -EINTR;
3543}
3544
3545static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3546{
3547 if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
3548 /*
3549 * The LSB of head.next can't change to 0 from under
3550 * us because we hold the mm_all_locks_mutex.
3551 *
3552 * We must however clear the bitflag before unlocking
3553 * the vma so the users using the anon_vma->rb_root will
3554 * never see our bitflag.
3555 *
3556 * No need of atomic instructions here, head.next
3557 * can't change from under us until we release the
3558 * anon_vma->root->rwsem.
3559 */
3560 if (!__test_and_clear_bit(0, (unsigned long *)
3561 &anon_vma->root->rb_root.rb_root.rb_node))
3562 BUG();
3563 anon_vma_unlock_write(anon_vma);
3564 }
3565}
3566
3567static void vm_unlock_mapping(struct address_space *mapping)
3568{
3569 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3570 /*
3571 * AS_MM_ALL_LOCKS can't change to 0 from under us
3572 * because we hold the mm_all_locks_mutex.
3573 */
3574 i_mmap_unlock_write(mapping);
3575 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
3576 &mapping->flags))
3577 BUG();
3578 }
3579}
3580
3581/*
3582 * The mmap_sem cannot be released by the caller until
3583 * mm_drop_all_locks() returns.
3584 */
3585void mm_drop_all_locks(struct mm_struct *mm)
3586{
3587 struct vm_area_struct *vma;
3588 struct anon_vma_chain *avc;
3589
3590 BUG_ON(down_read_trylock(&mm->mmap_sem));
3591 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3592
3593 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3594 if (vma->anon_vma)
3595 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3596 vm_unlock_anon_vma(avc->anon_vma);
3597 if (vma->vm_file && vma->vm_file->f_mapping)
3598 vm_unlock_mapping(vma->vm_file->f_mapping);
3599 }
3600
3601 mutex_unlock(&mm_all_locks_mutex);
3602}
3603
3604/*
3605 * initialise the percpu counter for VM
3606 */
3607void __init mmap_init(void)
3608{
3609 int ret;
3610
3611 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
3612 VM_BUG_ON(ret);
3613}
3614
3615/*
3616 * Initialise sysctl_user_reserve_kbytes.
3617 *
3618 * This is intended to prevent a user from starting a single memory hogging
3619 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3620 * mode.
3621 *
3622 * The default value is min(3% of free memory, 128MB)
3623 * 128MB is enough to recover with sshd/login, bash, and top/kill.
3624 */
3625static int init_user_reserve(void)
3626{
3627 unsigned long free_kbytes;
3628
3629 free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3630
3631 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
3632 return 0;
3633}
3634subsys_initcall(init_user_reserve);
3635
3636/*
3637 * Initialise sysctl_admin_reserve_kbytes.
3638 *
3639 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3640 * to log in and kill a memory hogging process.
3641 *
3642 * Systems with more than 256MB will reserve 8MB, enough to recover
3643 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3644 * only reserve 3% of free pages by default.
3645 */
3646static int init_admin_reserve(void)
3647{
3648 unsigned long free_kbytes;
3649
3650 free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3651
3652 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
3653 return 0;
3654}
3655subsys_initcall(init_admin_reserve);
3656
3657/*
3658 * Reinititalise user and admin reserves if memory is added or removed.
3659 *
3660 * The default user reserve max is 128MB, and the default max for the
3661 * admin reserve is 8MB. These are usually, but not always, enough to
3662 * enable recovery from a memory hogging process using login/sshd, a shell,
3663 * and tools like top. It may make sense to increase or even disable the
3664 * reserve depending on the existence of swap or variations in the recovery
3665 * tools. So, the admin may have changed them.
3666 *
3667 * If memory is added and the reserves have been eliminated or increased above
3668 * the default max, then we'll trust the admin.
3669 *
3670 * If memory is removed and there isn't enough free memory, then we
3671 * need to reset the reserves.
3672 *
3673 * Otherwise keep the reserve set by the admin.
3674 */
3675static int reserve_mem_notifier(struct notifier_block *nb,
3676 unsigned long action, void *data)
3677{
3678 unsigned long tmp, free_kbytes;
3679
3680 switch (action) {
3681 case MEM_ONLINE:
3682 /* Default max is 128MB. Leave alone if modified by operator. */
3683 tmp = sysctl_user_reserve_kbytes;
3684 if (0 < tmp && tmp < (1UL << 17))
3685 init_user_reserve();
3686
3687 /* Default max is 8MB. Leave alone if modified by operator. */
3688 tmp = sysctl_admin_reserve_kbytes;
3689 if (0 < tmp && tmp < (1UL << 13))
3690 init_admin_reserve();
3691
3692 break;
3693 case MEM_OFFLINE:
3694 free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3695
3696 if (sysctl_user_reserve_kbytes > free_kbytes) {
3697 init_user_reserve();
3698 pr_info("vm.user_reserve_kbytes reset to %lu\n",
3699 sysctl_user_reserve_kbytes);
3700 }
3701
3702 if (sysctl_admin_reserve_kbytes > free_kbytes) {
3703 init_admin_reserve();
3704 pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3705 sysctl_admin_reserve_kbytes);
3706 }
3707 break;
3708 default:
3709 break;
3710 }
3711 return NOTIFY_OK;
3712}
3713
3714static struct notifier_block reserve_mem_nb = {
3715 .notifier_call = reserve_mem_notifier,
3716};
3717
3718static int __meminit init_reserve_notifier(void)
3719{
3720 if (register_hotmemory_notifier(&reserve_mem_nb))
3721 pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3722
3723 return 0;
3724}
3725subsys_initcall(init_reserve_notifier);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * mm/mmap.c
4 *
5 * Written by obz.
6 *
7 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
8 */
9
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12#include <linux/kernel.h>
13#include <linux/slab.h>
14#include <linux/backing-dev.h>
15#include <linux/mm.h>
16#include <linux/vmacache.h>
17#include <linux/shm.h>
18#include <linux/mman.h>
19#include <linux/pagemap.h>
20#include <linux/swap.h>
21#include <linux/syscalls.h>
22#include <linux/capability.h>
23#include <linux/init.h>
24#include <linux/file.h>
25#include <linux/fs.h>
26#include <linux/personality.h>
27#include <linux/security.h>
28#include <linux/hugetlb.h>
29#include <linux/shmem_fs.h>
30#include <linux/profile.h>
31#include <linux/export.h>
32#include <linux/mount.h>
33#include <linux/mempolicy.h>
34#include <linux/rmap.h>
35#include <linux/mmu_notifier.h>
36#include <linux/mmdebug.h>
37#include <linux/perf_event.h>
38#include <linux/audit.h>
39#include <linux/khugepaged.h>
40#include <linux/uprobes.h>
41#include <linux/rbtree_augmented.h>
42#include <linux/notifier.h>
43#include <linux/memory.h>
44#include <linux/printk.h>
45#include <linux/userfaultfd_k.h>
46#include <linux/moduleparam.h>
47#include <linux/pkeys.h>
48#include <linux/oom.h>
49#include <linux/sched/mm.h>
50
51#include <linux/uaccess.h>
52#include <asm/cacheflush.h>
53#include <asm/tlb.h>
54#include <asm/mmu_context.h>
55
56#define CREATE_TRACE_POINTS
57#include <trace/events/mmap.h>
58
59#include "internal.h"
60
61#ifndef arch_mmap_check
62#define arch_mmap_check(addr, len, flags) (0)
63#endif
64
65#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
66const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
67const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX;
68int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
69#endif
70#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
71const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
72const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
73int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
74#endif
75
76static bool ignore_rlimit_data;
77core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
78
79static void unmap_region(struct mm_struct *mm,
80 struct vm_area_struct *vma, struct vm_area_struct *prev,
81 unsigned long start, unsigned long end);
82
83/* description of effects of mapping type and prot in current implementation.
84 * this is due to the limited x86 page protection hardware. The expected
85 * behavior is in parens:
86 *
87 * map_type prot
88 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
89 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
90 * w: (no) no w: (no) no w: (yes) yes w: (no) no
91 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
92 *
93 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
94 * w: (no) no w: (no) no w: (copy) copy w: (no) no
95 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
96 *
97 * On arm64, PROT_EXEC has the following behaviour for both MAP_SHARED and
98 * MAP_PRIVATE (with Enhanced PAN supported):
99 * r: (no) no
100 * w: (no) no
101 * x: (yes) yes
102 */
103pgprot_t protection_map[16] __ro_after_init = {
104 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
105 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
106};
107
108#ifndef CONFIG_ARCH_HAS_FILTER_PGPROT
109static inline pgprot_t arch_filter_pgprot(pgprot_t prot)
110{
111 return prot;
112}
113#endif
114
115pgprot_t vm_get_page_prot(unsigned long vm_flags)
116{
117 pgprot_t ret = __pgprot(pgprot_val(protection_map[vm_flags &
118 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
119 pgprot_val(arch_vm_get_page_prot(vm_flags)));
120
121 return arch_filter_pgprot(ret);
122}
123EXPORT_SYMBOL(vm_get_page_prot);
124
125static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
126{
127 return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
128}
129
130/* Update vma->vm_page_prot to reflect vma->vm_flags. */
131void vma_set_page_prot(struct vm_area_struct *vma)
132{
133 unsigned long vm_flags = vma->vm_flags;
134 pgprot_t vm_page_prot;
135
136 vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
137 if (vma_wants_writenotify(vma, vm_page_prot)) {
138 vm_flags &= ~VM_SHARED;
139 vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags);
140 }
141 /* remove_protection_ptes reads vma->vm_page_prot without mmap_lock */
142 WRITE_ONCE(vma->vm_page_prot, vm_page_prot);
143}
144
145/*
146 * Requires inode->i_mapping->i_mmap_rwsem
147 */
148static void __remove_shared_vm_struct(struct vm_area_struct *vma,
149 struct file *file, struct address_space *mapping)
150{
151 if (vma->vm_flags & VM_DENYWRITE)
152 allow_write_access(file);
153 if (vma->vm_flags & VM_SHARED)
154 mapping_unmap_writable(mapping);
155
156 flush_dcache_mmap_lock(mapping);
157 vma_interval_tree_remove(vma, &mapping->i_mmap);
158 flush_dcache_mmap_unlock(mapping);
159}
160
161/*
162 * Unlink a file-based vm structure from its interval tree, to hide
163 * vma from rmap and vmtruncate before freeing its page tables.
164 */
165void unlink_file_vma(struct vm_area_struct *vma)
166{
167 struct file *file = vma->vm_file;
168
169 if (file) {
170 struct address_space *mapping = file->f_mapping;
171 i_mmap_lock_write(mapping);
172 __remove_shared_vm_struct(vma, file, mapping);
173 i_mmap_unlock_write(mapping);
174 }
175}
176
177/*
178 * Close a vm structure and free it, returning the next.
179 */
180static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
181{
182 struct vm_area_struct *next = vma->vm_next;
183
184 might_sleep();
185 if (vma->vm_ops && vma->vm_ops->close)
186 vma->vm_ops->close(vma);
187 if (vma->vm_file)
188 fput(vma->vm_file);
189 mpol_put(vma_policy(vma));
190 vm_area_free(vma);
191 return next;
192}
193
194static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long flags,
195 struct list_head *uf);
196SYSCALL_DEFINE1(brk, unsigned long, brk)
197{
198 unsigned long newbrk, oldbrk, origbrk;
199 struct mm_struct *mm = current->mm;
200 struct vm_area_struct *next;
201 unsigned long min_brk;
202 bool populate;
203 bool downgraded = false;
204 LIST_HEAD(uf);
205
206 if (mmap_write_lock_killable(mm))
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_lock to read.
247 */
248 if (brk <= mm->brk) {
249 int ret;
250
251 /*
252 * mm->brk must to be protected by write mmap_lock so update it
253 * before downgrading mmap_lock. 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 mmap_read_unlock(mm);
281 else
282 mmap_write_unlock(mm);
283 userfaultfd_unmap_complete(mm, &uf);
284 if (populate)
285 mm_populate(oldbrk, newbrk - oldbrk);
286 return brk;
287
288out:
289 mmap_write_unlock(mm);
290 return origbrk;
291}
292
293static inline unsigned long vma_compute_gap(struct vm_area_struct *vma)
294{
295 unsigned long gap, prev_end;
296
297 /*
298 * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we
299 * allow two stack_guard_gaps between them here, and when choosing
300 * an unmapped area; whereas when expanding we only require one.
301 * That's a little inconsistent, but keeps the code here simpler.
302 */
303 gap = vm_start_gap(vma);
304 if (vma->vm_prev) {
305 prev_end = vm_end_gap(vma->vm_prev);
306 if (gap > prev_end)
307 gap -= prev_end;
308 else
309 gap = 0;
310 }
311 return gap;
312}
313
314#ifdef CONFIG_DEBUG_VM_RB
315static unsigned long vma_compute_subtree_gap(struct vm_area_struct *vma)
316{
317 unsigned long max = vma_compute_gap(vma), subtree_gap;
318 if (vma->vm_rb.rb_left) {
319 subtree_gap = rb_entry(vma->vm_rb.rb_left,
320 struct vm_area_struct, vm_rb)->rb_subtree_gap;
321 if (subtree_gap > max)
322 max = subtree_gap;
323 }
324 if (vma->vm_rb.rb_right) {
325 subtree_gap = rb_entry(vma->vm_rb.rb_right,
326 struct vm_area_struct, vm_rb)->rb_subtree_gap;
327 if (subtree_gap > max)
328 max = subtree_gap;
329 }
330 return max;
331}
332
333static int browse_rb(struct mm_struct *mm)
334{
335 struct rb_root *root = &mm->mm_rb;
336 int i = 0, j, bug = 0;
337 struct rb_node *nd, *pn = NULL;
338 unsigned long prev = 0, pend = 0;
339
340 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
341 struct vm_area_struct *vma;
342 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
343 if (vma->vm_start < prev) {
344 pr_emerg("vm_start %lx < prev %lx\n",
345 vma->vm_start, prev);
346 bug = 1;
347 }
348 if (vma->vm_start < pend) {
349 pr_emerg("vm_start %lx < pend %lx\n",
350 vma->vm_start, pend);
351 bug = 1;
352 }
353 if (vma->vm_start > vma->vm_end) {
354 pr_emerg("vm_start %lx > vm_end %lx\n",
355 vma->vm_start, vma->vm_end);
356 bug = 1;
357 }
358 spin_lock(&mm->page_table_lock);
359 if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
360 pr_emerg("free gap %lx, correct %lx\n",
361 vma->rb_subtree_gap,
362 vma_compute_subtree_gap(vma));
363 bug = 1;
364 }
365 spin_unlock(&mm->page_table_lock);
366 i++;
367 pn = nd;
368 prev = vma->vm_start;
369 pend = vma->vm_end;
370 }
371 j = 0;
372 for (nd = pn; nd; nd = rb_prev(nd))
373 j++;
374 if (i != j) {
375 pr_emerg("backwards %d, forwards %d\n", j, i);
376 bug = 1;
377 }
378 return bug ? -1 : i;
379}
380
381static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
382{
383 struct rb_node *nd;
384
385 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
386 struct vm_area_struct *vma;
387 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
388 VM_BUG_ON_VMA(vma != ignore &&
389 vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
390 vma);
391 }
392}
393
394static void validate_mm(struct mm_struct *mm)
395{
396 int bug = 0;
397 int i = 0;
398 unsigned long highest_address = 0;
399 struct vm_area_struct *vma = mm->mmap;
400
401 while (vma) {
402 struct anon_vma *anon_vma = vma->anon_vma;
403 struct anon_vma_chain *avc;
404
405 if (anon_vma) {
406 anon_vma_lock_read(anon_vma);
407 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
408 anon_vma_interval_tree_verify(avc);
409 anon_vma_unlock_read(anon_vma);
410 }
411
412 highest_address = vm_end_gap(vma);
413 vma = vma->vm_next;
414 i++;
415 }
416 if (i != mm->map_count) {
417 pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
418 bug = 1;
419 }
420 if (highest_address != mm->highest_vm_end) {
421 pr_emerg("mm->highest_vm_end %lx, found %lx\n",
422 mm->highest_vm_end, highest_address);
423 bug = 1;
424 }
425 i = browse_rb(mm);
426 if (i != mm->map_count) {
427 if (i != -1)
428 pr_emerg("map_count %d rb %d\n", mm->map_count, i);
429 bug = 1;
430 }
431 VM_BUG_ON_MM(bug, mm);
432}
433#else
434#define validate_mm_rb(root, ignore) do { } while (0)
435#define validate_mm(mm) do { } while (0)
436#endif
437
438RB_DECLARE_CALLBACKS_MAX(static, vma_gap_callbacks,
439 struct vm_area_struct, vm_rb,
440 unsigned long, rb_subtree_gap, vma_compute_gap)
441
442/*
443 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
444 * vma->vm_prev->vm_end values changed, without modifying the vma's position
445 * in the rbtree.
446 */
447static void vma_gap_update(struct vm_area_struct *vma)
448{
449 /*
450 * As it turns out, RB_DECLARE_CALLBACKS_MAX() already created
451 * a callback function that does exactly what we want.
452 */
453 vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
454}
455
456static inline void vma_rb_insert(struct vm_area_struct *vma,
457 struct rb_root *root)
458{
459 /* All rb_subtree_gap values must be consistent prior to insertion */
460 validate_mm_rb(root, NULL);
461
462 rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
463}
464
465static void __vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
466{
467 /*
468 * Note rb_erase_augmented is a fairly large inline function,
469 * so make sure we instantiate it only once with our desired
470 * augmented rbtree callbacks.
471 */
472 rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
473}
474
475static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma,
476 struct rb_root *root,
477 struct vm_area_struct *ignore)
478{
479 /*
480 * All rb_subtree_gap values must be consistent prior to erase,
481 * with the possible exception of
482 *
483 * a. the "next" vma being erased if next->vm_start was reduced in
484 * __vma_adjust() -> __vma_unlink()
485 * b. the vma being erased in detach_vmas_to_be_unmapped() ->
486 * vma_rb_erase()
487 */
488 validate_mm_rb(root, ignore);
489
490 __vma_rb_erase(vma, root);
491}
492
493static __always_inline void vma_rb_erase(struct vm_area_struct *vma,
494 struct rb_root *root)
495{
496 vma_rb_erase_ignore(vma, root, vma);
497}
498
499/*
500 * vma has some anon_vma assigned, and is already inserted on that
501 * anon_vma's interval trees.
502 *
503 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
504 * vma must be removed from the anon_vma's interval trees using
505 * anon_vma_interval_tree_pre_update_vma().
506 *
507 * After the update, the vma will be reinserted using
508 * anon_vma_interval_tree_post_update_vma().
509 *
510 * The entire update must be protected by exclusive mmap_lock and by
511 * the root anon_vma's mutex.
512 */
513static inline void
514anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
515{
516 struct anon_vma_chain *avc;
517
518 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
519 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
520}
521
522static inline void
523anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
524{
525 struct anon_vma_chain *avc;
526
527 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
528 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
529}
530
531static int find_vma_links(struct mm_struct *mm, unsigned long addr,
532 unsigned long end, struct vm_area_struct **pprev,
533 struct rb_node ***rb_link, struct rb_node **rb_parent)
534{
535 struct rb_node **__rb_link, *__rb_parent, *rb_prev;
536
537 __rb_link = &mm->mm_rb.rb_node;
538 rb_prev = __rb_parent = NULL;
539
540 while (*__rb_link) {
541 struct vm_area_struct *vma_tmp;
542
543 __rb_parent = *__rb_link;
544 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
545
546 if (vma_tmp->vm_end > addr) {
547 /* Fail if an existing vma overlaps the area */
548 if (vma_tmp->vm_start < end)
549 return -ENOMEM;
550 __rb_link = &__rb_parent->rb_left;
551 } else {
552 rb_prev = __rb_parent;
553 __rb_link = &__rb_parent->rb_right;
554 }
555 }
556
557 *pprev = NULL;
558 if (rb_prev)
559 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
560 *rb_link = __rb_link;
561 *rb_parent = __rb_parent;
562 return 0;
563}
564
565/*
566 * vma_next() - Get the next VMA.
567 * @mm: The mm_struct.
568 * @vma: The current vma.
569 *
570 * If @vma is NULL, return the first vma in the mm.
571 *
572 * Returns: The next VMA after @vma.
573 */
574static inline struct vm_area_struct *vma_next(struct mm_struct *mm,
575 struct vm_area_struct *vma)
576{
577 if (!vma)
578 return mm->mmap;
579
580 return vma->vm_next;
581}
582
583/*
584 * munmap_vma_range() - munmap VMAs that overlap a range.
585 * @mm: The mm struct
586 * @start: The start of the range.
587 * @len: The length of the range.
588 * @pprev: pointer to the pointer that will be set to previous vm_area_struct
589 * @rb_link: the rb_node
590 * @rb_parent: the parent rb_node
591 *
592 * Find all the vm_area_struct that overlap from @start to
593 * @end and munmap them. Set @pprev to the previous vm_area_struct.
594 *
595 * Returns: -ENOMEM on munmap failure or 0 on success.
596 */
597static inline int
598munmap_vma_range(struct mm_struct *mm, unsigned long start, unsigned long len,
599 struct vm_area_struct **pprev, struct rb_node ***link,
600 struct rb_node **parent, struct list_head *uf)
601{
602
603 while (find_vma_links(mm, start, start + len, pprev, link, parent))
604 if (do_munmap(mm, start, len, uf))
605 return -ENOMEM;
606
607 return 0;
608}
609static unsigned long count_vma_pages_range(struct mm_struct *mm,
610 unsigned long addr, unsigned long end)
611{
612 unsigned long nr_pages = 0;
613 struct vm_area_struct *vma;
614
615 /* Find first overlapping mapping */
616 vma = find_vma_intersection(mm, addr, end);
617 if (!vma)
618 return 0;
619
620 nr_pages = (min(end, vma->vm_end) -
621 max(addr, vma->vm_start)) >> PAGE_SHIFT;
622
623 /* Iterate over the rest of the overlaps */
624 for (vma = vma->vm_next; vma; vma = vma->vm_next) {
625 unsigned long overlap_len;
626
627 if (vma->vm_start > end)
628 break;
629
630 overlap_len = min(end, vma->vm_end) - vma->vm_start;
631 nr_pages += overlap_len >> PAGE_SHIFT;
632 }
633
634 return nr_pages;
635}
636
637void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
638 struct rb_node **rb_link, struct rb_node *rb_parent)
639{
640 /* Update tracking information for the gap following the new vma. */
641 if (vma->vm_next)
642 vma_gap_update(vma->vm_next);
643 else
644 mm->highest_vm_end = vm_end_gap(vma);
645
646 /*
647 * vma->vm_prev wasn't known when we followed the rbtree to find the
648 * correct insertion point for that vma. As a result, we could not
649 * update the vma vm_rb parents rb_subtree_gap values on the way down.
650 * So, we first insert the vma with a zero rb_subtree_gap value
651 * (to be consistent with what we did on the way down), and then
652 * immediately update the gap to the correct value. Finally we
653 * rebalance the rbtree after all augmented values have been set.
654 */
655 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
656 vma->rb_subtree_gap = 0;
657 vma_gap_update(vma);
658 vma_rb_insert(vma, &mm->mm_rb);
659}
660
661static void __vma_link_file(struct vm_area_struct *vma)
662{
663 struct file *file;
664
665 file = vma->vm_file;
666 if (file) {
667 struct address_space *mapping = file->f_mapping;
668
669 if (vma->vm_flags & VM_DENYWRITE)
670 put_write_access(file_inode(file));
671 if (vma->vm_flags & VM_SHARED)
672 mapping_allow_writable(mapping);
673
674 flush_dcache_mmap_lock(mapping);
675 vma_interval_tree_insert(vma, &mapping->i_mmap);
676 flush_dcache_mmap_unlock(mapping);
677 }
678}
679
680static void
681__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
682 struct vm_area_struct *prev, struct rb_node **rb_link,
683 struct rb_node *rb_parent)
684{
685 __vma_link_list(mm, vma, prev);
686 __vma_link_rb(mm, vma, rb_link, rb_parent);
687}
688
689static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
690 struct vm_area_struct *prev, struct rb_node **rb_link,
691 struct rb_node *rb_parent)
692{
693 struct address_space *mapping = NULL;
694
695 if (vma->vm_file) {
696 mapping = vma->vm_file->f_mapping;
697 i_mmap_lock_write(mapping);
698 }
699
700 __vma_link(mm, vma, prev, rb_link, rb_parent);
701 __vma_link_file(vma);
702
703 if (mapping)
704 i_mmap_unlock_write(mapping);
705
706 mm->map_count++;
707 validate_mm(mm);
708}
709
710/*
711 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
712 * mm's list and rbtree. It has already been inserted into the interval tree.
713 */
714static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
715{
716 struct vm_area_struct *prev;
717 struct rb_node **rb_link, *rb_parent;
718
719 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
720 &prev, &rb_link, &rb_parent))
721 BUG();
722 __vma_link(mm, vma, prev, rb_link, rb_parent);
723 mm->map_count++;
724}
725
726static __always_inline void __vma_unlink(struct mm_struct *mm,
727 struct vm_area_struct *vma,
728 struct vm_area_struct *ignore)
729{
730 vma_rb_erase_ignore(vma, &mm->mm_rb, ignore);
731 __vma_unlink_list(mm, vma);
732 /* Kill the cache */
733 vmacache_invalidate(mm);
734}
735
736/*
737 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
738 * is already present in an i_mmap tree without adjusting the tree.
739 * The following helper function should be used when such adjustments
740 * are necessary. The "insert" vma (if any) is to be inserted
741 * before we drop the necessary locks.
742 */
743int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
744 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert,
745 struct vm_area_struct *expand)
746{
747 struct mm_struct *mm = vma->vm_mm;
748 struct vm_area_struct *next = vma->vm_next, *orig_vma = vma;
749 struct address_space *mapping = NULL;
750 struct rb_root_cached *root = NULL;
751 struct anon_vma *anon_vma = NULL;
752 struct file *file = vma->vm_file;
753 bool start_changed = false, end_changed = false;
754 long adjust_next = 0;
755 int remove_next = 0;
756
757 if (next && !insert) {
758 struct vm_area_struct *exporter = NULL, *importer = NULL;
759
760 if (end >= next->vm_end) {
761 /*
762 * vma expands, overlapping all the next, and
763 * perhaps the one after too (mprotect case 6).
764 * The only other cases that gets here are
765 * case 1, case 7 and case 8.
766 */
767 if (next == expand) {
768 /*
769 * The only case where we don't expand "vma"
770 * and we expand "next" instead is case 8.
771 */
772 VM_WARN_ON(end != next->vm_end);
773 /*
774 * remove_next == 3 means we're
775 * removing "vma" and that to do so we
776 * swapped "vma" and "next".
777 */
778 remove_next = 3;
779 VM_WARN_ON(file != next->vm_file);
780 swap(vma, next);
781 } else {
782 VM_WARN_ON(expand != vma);
783 /*
784 * case 1, 6, 7, remove_next == 2 is case 6,
785 * remove_next == 1 is case 1 or 7.
786 */
787 remove_next = 1 + (end > next->vm_end);
788 VM_WARN_ON(remove_next == 2 &&
789 end != next->vm_next->vm_end);
790 /* trim end to next, for case 6 first pass */
791 end = next->vm_end;
792 }
793
794 exporter = next;
795 importer = vma;
796
797 /*
798 * If next doesn't have anon_vma, import from vma after
799 * next, if the vma overlaps with it.
800 */
801 if (remove_next == 2 && !next->anon_vma)
802 exporter = next->vm_next;
803
804 } else if (end > next->vm_start) {
805 /*
806 * vma expands, overlapping part of the next:
807 * mprotect case 5 shifting the boundary up.
808 */
809 adjust_next = (end - next->vm_start);
810 exporter = next;
811 importer = vma;
812 VM_WARN_ON(expand != importer);
813 } else if (end < vma->vm_end) {
814 /*
815 * vma shrinks, and !insert tells it's not
816 * split_vma inserting another: so it must be
817 * mprotect case 4 shifting the boundary down.
818 */
819 adjust_next = -(vma->vm_end - end);
820 exporter = vma;
821 importer = next;
822 VM_WARN_ON(expand != importer);
823 }
824
825 /*
826 * Easily overlooked: when mprotect shifts the boundary,
827 * make sure the expanding vma has anon_vma set if the
828 * shrinking vma had, to cover any anon pages imported.
829 */
830 if (exporter && exporter->anon_vma && !importer->anon_vma) {
831 int error;
832
833 importer->anon_vma = exporter->anon_vma;
834 error = anon_vma_clone(importer, exporter);
835 if (error)
836 return error;
837 }
838 }
839again:
840 vma_adjust_trans_huge(orig_vma, start, end, adjust_next);
841
842 if (file) {
843 mapping = file->f_mapping;
844 root = &mapping->i_mmap;
845 uprobe_munmap(vma, vma->vm_start, vma->vm_end);
846
847 if (adjust_next)
848 uprobe_munmap(next, next->vm_start, next->vm_end);
849
850 i_mmap_lock_write(mapping);
851 if (insert) {
852 /*
853 * Put into interval tree now, so instantiated pages
854 * are visible to arm/parisc __flush_dcache_page
855 * throughout; but we cannot insert into address
856 * space until vma start or end is updated.
857 */
858 __vma_link_file(insert);
859 }
860 }
861
862 anon_vma = vma->anon_vma;
863 if (!anon_vma && adjust_next)
864 anon_vma = next->anon_vma;
865 if (anon_vma) {
866 VM_WARN_ON(adjust_next && next->anon_vma &&
867 anon_vma != next->anon_vma);
868 anon_vma_lock_write(anon_vma);
869 anon_vma_interval_tree_pre_update_vma(vma);
870 if (adjust_next)
871 anon_vma_interval_tree_pre_update_vma(next);
872 }
873
874 if (file) {
875 flush_dcache_mmap_lock(mapping);
876 vma_interval_tree_remove(vma, root);
877 if (adjust_next)
878 vma_interval_tree_remove(next, root);
879 }
880
881 if (start != vma->vm_start) {
882 vma->vm_start = start;
883 start_changed = true;
884 }
885 if (end != vma->vm_end) {
886 vma->vm_end = end;
887 end_changed = true;
888 }
889 vma->vm_pgoff = pgoff;
890 if (adjust_next) {
891 next->vm_start += adjust_next;
892 next->vm_pgoff += adjust_next >> PAGE_SHIFT;
893 }
894
895 if (file) {
896 if (adjust_next)
897 vma_interval_tree_insert(next, root);
898 vma_interval_tree_insert(vma, root);
899 flush_dcache_mmap_unlock(mapping);
900 }
901
902 if (remove_next) {
903 /*
904 * vma_merge has merged next into vma, and needs
905 * us to remove next before dropping the locks.
906 */
907 if (remove_next != 3)
908 __vma_unlink(mm, next, next);
909 else
910 /*
911 * vma is not before next if they've been
912 * swapped.
913 *
914 * pre-swap() next->vm_start was reduced so
915 * tell validate_mm_rb to ignore pre-swap()
916 * "next" (which is stored in post-swap()
917 * "vma").
918 */
919 __vma_unlink(mm, next, vma);
920 if (file)
921 __remove_shared_vm_struct(next, file, mapping);
922 } else if (insert) {
923 /*
924 * split_vma has split insert from vma, and needs
925 * us to insert it before dropping the locks
926 * (it may either follow vma or precede it).
927 */
928 __insert_vm_struct(mm, insert);
929 } else {
930 if (start_changed)
931 vma_gap_update(vma);
932 if (end_changed) {
933 if (!next)
934 mm->highest_vm_end = vm_end_gap(vma);
935 else if (!adjust_next)
936 vma_gap_update(next);
937 }
938 }
939
940 if (anon_vma) {
941 anon_vma_interval_tree_post_update_vma(vma);
942 if (adjust_next)
943 anon_vma_interval_tree_post_update_vma(next);
944 anon_vma_unlock_write(anon_vma);
945 }
946
947 if (file) {
948 i_mmap_unlock_write(mapping);
949 uprobe_mmap(vma);
950
951 if (adjust_next)
952 uprobe_mmap(next);
953 }
954
955 if (remove_next) {
956 if (file) {
957 uprobe_munmap(next, next->vm_start, next->vm_end);
958 fput(file);
959 }
960 if (next->anon_vma)
961 anon_vma_merge(vma, next);
962 mm->map_count--;
963 mpol_put(vma_policy(next));
964 vm_area_free(next);
965 /*
966 * In mprotect's case 6 (see comments on vma_merge),
967 * we must remove another next too. It would clutter
968 * up the code too much to do both in one go.
969 */
970 if (remove_next != 3) {
971 /*
972 * If "next" was removed and vma->vm_end was
973 * expanded (up) over it, in turn
974 * "next->vm_prev->vm_end" changed and the
975 * "vma->vm_next" gap must be updated.
976 */
977 next = vma->vm_next;
978 } else {
979 /*
980 * For the scope of the comment "next" and
981 * "vma" considered pre-swap(): if "vma" was
982 * removed, next->vm_start was expanded (down)
983 * over it and the "next" gap must be updated.
984 * Because of the swap() the post-swap() "vma"
985 * actually points to pre-swap() "next"
986 * (post-swap() "next" as opposed is now a
987 * dangling pointer).
988 */
989 next = vma;
990 }
991 if (remove_next == 2) {
992 remove_next = 1;
993 end = next->vm_end;
994 goto again;
995 }
996 else if (next)
997 vma_gap_update(next);
998 else {
999 /*
1000 * If remove_next == 2 we obviously can't
1001 * reach this path.
1002 *
1003 * If remove_next == 3 we can't reach this
1004 * path because pre-swap() next is always not
1005 * NULL. pre-swap() "next" is not being
1006 * removed and its next->vm_end is not altered
1007 * (and furthermore "end" already matches
1008 * next->vm_end in remove_next == 3).
1009 *
1010 * We reach this only in the remove_next == 1
1011 * case if the "next" vma that was removed was
1012 * the highest vma of the mm. However in such
1013 * case next->vm_end == "end" and the extended
1014 * "vma" has vma->vm_end == next->vm_end so
1015 * mm->highest_vm_end doesn't need any update
1016 * in remove_next == 1 case.
1017 */
1018 VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
1019 }
1020 }
1021 if (insert && file)
1022 uprobe_mmap(insert);
1023
1024 validate_mm(mm);
1025
1026 return 0;
1027}
1028
1029/*
1030 * If the vma has a ->close operation then the driver probably needs to release
1031 * per-vma resources, so we don't attempt to merge those.
1032 */
1033static inline int is_mergeable_vma(struct vm_area_struct *vma,
1034 struct file *file, unsigned long vm_flags,
1035 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1036{
1037 /*
1038 * VM_SOFTDIRTY should not prevent from VMA merging, if we
1039 * match the flags but dirty bit -- the caller should mark
1040 * merged VMA as dirty. If dirty bit won't be excluded from
1041 * comparison, we increase pressure on the memory system forcing
1042 * the kernel to generate new VMAs when old one could be
1043 * extended instead.
1044 */
1045 if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
1046 return 0;
1047 if (vma->vm_file != file)
1048 return 0;
1049 if (vma->vm_ops && vma->vm_ops->close)
1050 return 0;
1051 if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
1052 return 0;
1053 return 1;
1054}
1055
1056static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
1057 struct anon_vma *anon_vma2,
1058 struct vm_area_struct *vma)
1059{
1060 /*
1061 * The list_is_singular() test is to avoid merging VMA cloned from
1062 * parents. This can improve scalability caused by anon_vma lock.
1063 */
1064 if ((!anon_vma1 || !anon_vma2) && (!vma ||
1065 list_is_singular(&vma->anon_vma_chain)))
1066 return 1;
1067 return anon_vma1 == anon_vma2;
1068}
1069
1070/*
1071 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
1072 * in front of (at a lower virtual address and file offset than) the vma.
1073 *
1074 * We cannot merge two vmas if they have differently assigned (non-NULL)
1075 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
1076 *
1077 * We don't check here for the merged mmap wrapping around the end of pagecache
1078 * indices (16TB on ia32) because do_mmap() does not permit mmap's which
1079 * wrap, nor mmaps which cover the final page at index -1UL.
1080 */
1081static int
1082can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
1083 struct anon_vma *anon_vma, struct file *file,
1084 pgoff_t vm_pgoff,
1085 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1086{
1087 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
1088 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
1089 if (vma->vm_pgoff == vm_pgoff)
1090 return 1;
1091 }
1092 return 0;
1093}
1094
1095/*
1096 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
1097 * beyond (at a higher virtual address and file offset than) the vma.
1098 *
1099 * We cannot merge two vmas if they have differently assigned (non-NULL)
1100 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
1101 */
1102static int
1103can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
1104 struct anon_vma *anon_vma, struct file *file,
1105 pgoff_t vm_pgoff,
1106 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1107{
1108 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
1109 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
1110 pgoff_t vm_pglen;
1111 vm_pglen = vma_pages(vma);
1112 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
1113 return 1;
1114 }
1115 return 0;
1116}
1117
1118/*
1119 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
1120 * whether that can be merged with its predecessor or its successor.
1121 * Or both (it neatly fills a hole).
1122 *
1123 * In most cases - when called for mmap, brk or mremap - [addr,end) is
1124 * certain not to be mapped by the time vma_merge is called; but when
1125 * called for mprotect, it is certain to be already mapped (either at
1126 * an offset within prev, or at the start of next), and the flags of
1127 * this area are about to be changed to vm_flags - and the no-change
1128 * case has already been eliminated.
1129 *
1130 * The following mprotect cases have to be considered, where AAAA is
1131 * the area passed down from mprotect_fixup, never extending beyond one
1132 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
1133 *
1134 * AAAA AAAA AAAA
1135 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN
1136 * cannot merge might become might become
1137 * PPNNNNNNNNNN PPPPPPPPPPNN
1138 * mmap, brk or case 4 below case 5 below
1139 * mremap move:
1140 * AAAA AAAA
1141 * PPPP NNNN PPPPNNNNXXXX
1142 * might become might become
1143 * PPPPPPPPPPPP 1 or PPPPPPPPPPPP 6 or
1144 * PPPPPPPPNNNN 2 or PPPPPPPPXXXX 7 or
1145 * PPPPNNNNNNNN 3 PPPPXXXXXXXX 8
1146 *
1147 * It is important for case 8 that the vma NNNN overlapping the
1148 * region AAAA is never going to extended over XXXX. Instead XXXX must
1149 * be extended in region AAAA and NNNN must be removed. This way in
1150 * all cases where vma_merge succeeds, the moment vma_adjust drops the
1151 * rmap_locks, the properties of the merged vma will be already
1152 * correct for the whole merged range. Some of those properties like
1153 * vm_page_prot/vm_flags may be accessed by rmap_walks and they must
1154 * be correct for the whole merged range immediately after the
1155 * rmap_locks are released. Otherwise if XXXX would be removed and
1156 * NNNN would be extended over the XXXX range, remove_migration_ptes
1157 * or other rmap walkers (if working on addresses beyond the "end"
1158 * parameter) may establish ptes with the wrong permissions of NNNN
1159 * instead of the right permissions of XXXX.
1160 */
1161struct vm_area_struct *vma_merge(struct mm_struct *mm,
1162 struct vm_area_struct *prev, unsigned long addr,
1163 unsigned long end, unsigned long vm_flags,
1164 struct anon_vma *anon_vma, struct file *file,
1165 pgoff_t pgoff, struct mempolicy *policy,
1166 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1167{
1168 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
1169 struct vm_area_struct *area, *next;
1170 int err;
1171
1172 /*
1173 * We later require that vma->vm_flags == vm_flags,
1174 * so this tests vma->vm_flags & VM_SPECIAL, too.
1175 */
1176 if (vm_flags & VM_SPECIAL)
1177 return NULL;
1178
1179 next = vma_next(mm, prev);
1180 area = next;
1181 if (area && area->vm_end == end) /* cases 6, 7, 8 */
1182 next = next->vm_next;
1183
1184 /* verify some invariant that must be enforced by the caller */
1185 VM_WARN_ON(prev && addr <= prev->vm_start);
1186 VM_WARN_ON(area && end > area->vm_end);
1187 VM_WARN_ON(addr >= end);
1188
1189 /*
1190 * Can it merge with the predecessor?
1191 */
1192 if (prev && prev->vm_end == addr &&
1193 mpol_equal(vma_policy(prev), policy) &&
1194 can_vma_merge_after(prev, vm_flags,
1195 anon_vma, file, pgoff,
1196 vm_userfaultfd_ctx)) {
1197 /*
1198 * OK, it can. Can we now merge in the successor as well?
1199 */
1200 if (next && end == next->vm_start &&
1201 mpol_equal(policy, vma_policy(next)) &&
1202 can_vma_merge_before(next, vm_flags,
1203 anon_vma, file,
1204 pgoff+pglen,
1205 vm_userfaultfd_ctx) &&
1206 is_mergeable_anon_vma(prev->anon_vma,
1207 next->anon_vma, NULL)) {
1208 /* cases 1, 6 */
1209 err = __vma_adjust(prev, prev->vm_start,
1210 next->vm_end, prev->vm_pgoff, NULL,
1211 prev);
1212 } else /* cases 2, 5, 7 */
1213 err = __vma_adjust(prev, prev->vm_start,
1214 end, prev->vm_pgoff, NULL, prev);
1215 if (err)
1216 return NULL;
1217 khugepaged_enter_vma_merge(prev, vm_flags);
1218 return prev;
1219 }
1220
1221 /*
1222 * Can this new request be merged in front of next?
1223 */
1224 if (next && end == next->vm_start &&
1225 mpol_equal(policy, vma_policy(next)) &&
1226 can_vma_merge_before(next, vm_flags,
1227 anon_vma, file, pgoff+pglen,
1228 vm_userfaultfd_ctx)) {
1229 if (prev && addr < prev->vm_end) /* case 4 */
1230 err = __vma_adjust(prev, prev->vm_start,
1231 addr, prev->vm_pgoff, NULL, next);
1232 else { /* cases 3, 8 */
1233 err = __vma_adjust(area, addr, next->vm_end,
1234 next->vm_pgoff - pglen, NULL, next);
1235 /*
1236 * In case 3 area is already equal to next and
1237 * this is a noop, but in case 8 "area" has
1238 * been removed and next was expanded over it.
1239 */
1240 area = next;
1241 }
1242 if (err)
1243 return NULL;
1244 khugepaged_enter_vma_merge(area, vm_flags);
1245 return area;
1246 }
1247
1248 return NULL;
1249}
1250
1251/*
1252 * Rough compatibility check to quickly see if it's even worth looking
1253 * at sharing an anon_vma.
1254 *
1255 * They need to have the same vm_file, and the flags can only differ
1256 * in things that mprotect may change.
1257 *
1258 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1259 * we can merge the two vma's. For example, we refuse to merge a vma if
1260 * there is a vm_ops->close() function, because that indicates that the
1261 * driver is doing some kind of reference counting. But that doesn't
1262 * really matter for the anon_vma sharing case.
1263 */
1264static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1265{
1266 return a->vm_end == b->vm_start &&
1267 mpol_equal(vma_policy(a), vma_policy(b)) &&
1268 a->vm_file == b->vm_file &&
1269 !((a->vm_flags ^ b->vm_flags) & ~(VM_ACCESS_FLAGS | VM_SOFTDIRTY)) &&
1270 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1271}
1272
1273/*
1274 * Do some basic sanity checking to see if we can re-use the anon_vma
1275 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1276 * the same as 'old', the other will be the new one that is trying
1277 * to share the anon_vma.
1278 *
1279 * NOTE! This runs with mm_sem held for reading, so it is possible that
1280 * the anon_vma of 'old' is concurrently in the process of being set up
1281 * by another page fault trying to merge _that_. But that's ok: if it
1282 * is being set up, that automatically means that it will be a singleton
1283 * acceptable for merging, so we can do all of this optimistically. But
1284 * we do that READ_ONCE() to make sure that we never re-load the pointer.
1285 *
1286 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1287 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1288 * is to return an anon_vma that is "complex" due to having gone through
1289 * a fork).
1290 *
1291 * We also make sure that the two vma's are compatible (adjacent,
1292 * and with the same memory policies). That's all stable, even with just
1293 * a read lock on the mm_sem.
1294 */
1295static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1296{
1297 if (anon_vma_compatible(a, b)) {
1298 struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
1299
1300 if (anon_vma && list_is_singular(&old->anon_vma_chain))
1301 return anon_vma;
1302 }
1303 return NULL;
1304}
1305
1306/*
1307 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1308 * neighbouring vmas for a suitable anon_vma, before it goes off
1309 * to allocate a new anon_vma. It checks because a repetitive
1310 * sequence of mprotects and faults may otherwise lead to distinct
1311 * anon_vmas being allocated, preventing vma merge in subsequent
1312 * mprotect.
1313 */
1314struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1315{
1316 struct anon_vma *anon_vma = NULL;
1317
1318 /* Try next first. */
1319 if (vma->vm_next) {
1320 anon_vma = reusable_anon_vma(vma->vm_next, vma, vma->vm_next);
1321 if (anon_vma)
1322 return anon_vma;
1323 }
1324
1325 /* Try prev next. */
1326 if (vma->vm_prev)
1327 anon_vma = reusable_anon_vma(vma->vm_prev, vma->vm_prev, vma);
1328
1329 /*
1330 * We might reach here with anon_vma == NULL if we can't find
1331 * any reusable anon_vma.
1332 * There's no absolute need to look only at touching neighbours:
1333 * we could search further afield for "compatible" anon_vmas.
1334 * But it would probably just be a waste of time searching,
1335 * or lead to too many vmas hanging off the same anon_vma.
1336 * We're trying to allow mprotect remerging later on,
1337 * not trying to minimize memory used for anon_vmas.
1338 */
1339 return anon_vma;
1340}
1341
1342/*
1343 * If a hint addr is less than mmap_min_addr change hint to be as
1344 * low as possible but still greater than mmap_min_addr
1345 */
1346static inline unsigned long round_hint_to_min(unsigned long hint)
1347{
1348 hint &= PAGE_MASK;
1349 if (((void *)hint != NULL) &&
1350 (hint < mmap_min_addr))
1351 return PAGE_ALIGN(mmap_min_addr);
1352 return hint;
1353}
1354
1355int mlock_future_check(struct mm_struct *mm, unsigned long flags,
1356 unsigned long len)
1357{
1358 unsigned long locked, lock_limit;
1359
1360 /* mlock MCL_FUTURE? */
1361 if (flags & VM_LOCKED) {
1362 locked = len >> PAGE_SHIFT;
1363 locked += mm->locked_vm;
1364 lock_limit = rlimit(RLIMIT_MEMLOCK);
1365 lock_limit >>= PAGE_SHIFT;
1366 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1367 return -EAGAIN;
1368 }
1369 return 0;
1370}
1371
1372static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
1373{
1374 if (S_ISREG(inode->i_mode))
1375 return MAX_LFS_FILESIZE;
1376
1377 if (S_ISBLK(inode->i_mode))
1378 return MAX_LFS_FILESIZE;
1379
1380 if (S_ISSOCK(inode->i_mode))
1381 return MAX_LFS_FILESIZE;
1382
1383 /* Special "we do even unsigned file positions" case */
1384 if (file->f_mode & FMODE_UNSIGNED_OFFSET)
1385 return 0;
1386
1387 /* Yes, random drivers might want more. But I'm tired of buggy drivers */
1388 return ULONG_MAX;
1389}
1390
1391static inline bool file_mmap_ok(struct file *file, struct inode *inode,
1392 unsigned long pgoff, unsigned long len)
1393{
1394 u64 maxsize = file_mmap_size_max(file, inode);
1395
1396 if (maxsize && len > maxsize)
1397 return false;
1398 maxsize -= len;
1399 if (pgoff > maxsize >> PAGE_SHIFT)
1400 return false;
1401 return true;
1402}
1403
1404/*
1405 * The caller must write-lock current->mm->mmap_lock.
1406 */
1407unsigned long do_mmap(struct file *file, unsigned long addr,
1408 unsigned long len, unsigned long prot,
1409 unsigned long flags, unsigned long pgoff,
1410 unsigned long *populate, struct list_head *uf)
1411{
1412 struct mm_struct *mm = current->mm;
1413 vm_flags_t vm_flags;
1414 int pkey = 0;
1415
1416 *populate = 0;
1417
1418 if (!len)
1419 return -EINVAL;
1420
1421 /*
1422 * Does the application expect PROT_READ to imply PROT_EXEC?
1423 *
1424 * (the exception is when the underlying filesystem is noexec
1425 * mounted, in which case we dont add PROT_EXEC.)
1426 */
1427 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1428 if (!(file && path_noexec(&file->f_path)))
1429 prot |= PROT_EXEC;
1430
1431 /* force arch specific MAP_FIXED handling in get_unmapped_area */
1432 if (flags & MAP_FIXED_NOREPLACE)
1433 flags |= MAP_FIXED;
1434
1435 if (!(flags & MAP_FIXED))
1436 addr = round_hint_to_min(addr);
1437
1438 /* Careful about overflows.. */
1439 len = PAGE_ALIGN(len);
1440 if (!len)
1441 return -ENOMEM;
1442
1443 /* offset overflow? */
1444 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1445 return -EOVERFLOW;
1446
1447 /* Too many mappings? */
1448 if (mm->map_count > sysctl_max_map_count)
1449 return -ENOMEM;
1450
1451 /* Obtain the address to map to. we verify (or select) it and ensure
1452 * that it represents a valid section of the address space.
1453 */
1454 addr = get_unmapped_area(file, addr, len, pgoff, flags);
1455 if (IS_ERR_VALUE(addr))
1456 return addr;
1457
1458 if (flags & MAP_FIXED_NOREPLACE) {
1459 if (find_vma_intersection(mm, addr, addr + len))
1460 return -EEXIST;
1461 }
1462
1463 if (prot == PROT_EXEC) {
1464 pkey = execute_only_pkey(mm);
1465 if (pkey < 0)
1466 pkey = 0;
1467 }
1468
1469 /* Do simple checking here so the lower-level routines won't have
1470 * to. we assume access permissions have been handled by the open
1471 * of the memory object, so we don't do any here.
1472 */
1473 vm_flags = calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
1474 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1475
1476 if (flags & MAP_LOCKED)
1477 if (!can_do_mlock())
1478 return -EPERM;
1479
1480 if (mlock_future_check(mm, vm_flags, len))
1481 return -EAGAIN;
1482
1483 if (file) {
1484 struct inode *inode = file_inode(file);
1485 unsigned long flags_mask;
1486
1487 if (!file_mmap_ok(file, inode, pgoff, len))
1488 return -EOVERFLOW;
1489
1490 flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags;
1491
1492 switch (flags & MAP_TYPE) {
1493 case MAP_SHARED:
1494 /*
1495 * Force use of MAP_SHARED_VALIDATE with non-legacy
1496 * flags. E.g. MAP_SYNC is dangerous to use with
1497 * MAP_SHARED as you don't know which consistency model
1498 * you will get. We silently ignore unsupported flags
1499 * with MAP_SHARED to preserve backward compatibility.
1500 */
1501 flags &= LEGACY_MAP_MASK;
1502 fallthrough;
1503 case MAP_SHARED_VALIDATE:
1504 if (flags & ~flags_mask)
1505 return -EOPNOTSUPP;
1506 if (prot & PROT_WRITE) {
1507 if (!(file->f_mode & FMODE_WRITE))
1508 return -EACCES;
1509 if (IS_SWAPFILE(file->f_mapping->host))
1510 return -ETXTBSY;
1511 }
1512
1513 /*
1514 * Make sure we don't allow writing to an append-only
1515 * file..
1516 */
1517 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1518 return -EACCES;
1519
1520 /*
1521 * Make sure there are no mandatory locks on the file.
1522 */
1523 if (locks_verify_locked(file))
1524 return -EAGAIN;
1525
1526 vm_flags |= VM_SHARED | VM_MAYSHARE;
1527 if (!(file->f_mode & FMODE_WRITE))
1528 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1529 fallthrough;
1530 case MAP_PRIVATE:
1531 if (!(file->f_mode & FMODE_READ))
1532 return -EACCES;
1533 if (path_noexec(&file->f_path)) {
1534 if (vm_flags & VM_EXEC)
1535 return -EPERM;
1536 vm_flags &= ~VM_MAYEXEC;
1537 }
1538
1539 if (!file->f_op->mmap)
1540 return -ENODEV;
1541 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1542 return -EINVAL;
1543 break;
1544
1545 default:
1546 return -EINVAL;
1547 }
1548 } else {
1549 switch (flags & MAP_TYPE) {
1550 case MAP_SHARED:
1551 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1552 return -EINVAL;
1553 /*
1554 * Ignore pgoff.
1555 */
1556 pgoff = 0;
1557 vm_flags |= VM_SHARED | VM_MAYSHARE;
1558 break;
1559 case MAP_PRIVATE:
1560 /*
1561 * Set pgoff according to addr for anon_vma.
1562 */
1563 pgoff = addr >> PAGE_SHIFT;
1564 break;
1565 default:
1566 return -EINVAL;
1567 }
1568 }
1569
1570 /*
1571 * Set 'VM_NORESERVE' if we should not account for the
1572 * memory use of this mapping.
1573 */
1574 if (flags & MAP_NORESERVE) {
1575 /* We honor MAP_NORESERVE if allowed to overcommit */
1576 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1577 vm_flags |= VM_NORESERVE;
1578
1579 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1580 if (file && is_file_hugepages(file))
1581 vm_flags |= VM_NORESERVE;
1582 }
1583
1584 addr = mmap_region(file, addr, len, vm_flags, pgoff, uf);
1585 if (!IS_ERR_VALUE(addr) &&
1586 ((vm_flags & VM_LOCKED) ||
1587 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1588 *populate = len;
1589 return addr;
1590}
1591
1592unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
1593 unsigned long prot, unsigned long flags,
1594 unsigned long fd, unsigned long pgoff)
1595{
1596 struct file *file = NULL;
1597 unsigned long retval;
1598
1599 if (!(flags & MAP_ANONYMOUS)) {
1600 audit_mmap_fd(fd, flags);
1601 file = fget(fd);
1602 if (!file)
1603 return -EBADF;
1604 if (is_file_hugepages(file)) {
1605 len = ALIGN(len, huge_page_size(hstate_file(file)));
1606 } else if (unlikely(flags & MAP_HUGETLB)) {
1607 retval = -EINVAL;
1608 goto out_fput;
1609 }
1610 } else if (flags & MAP_HUGETLB) {
1611 struct ucounts *ucounts = NULL;
1612 struct hstate *hs;
1613
1614 hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1615 if (!hs)
1616 return -EINVAL;
1617
1618 len = ALIGN(len, huge_page_size(hs));
1619 /*
1620 * VM_NORESERVE is used because the reservations will be
1621 * taken when vm_ops->mmap() is called
1622 * A dummy user value is used because we are not locking
1623 * memory so no accounting is necessary
1624 */
1625 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1626 VM_NORESERVE,
1627 &ucounts, HUGETLB_ANONHUGE_INODE,
1628 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1629 if (IS_ERR(file))
1630 return PTR_ERR(file);
1631 }
1632
1633 flags &= ~MAP_DENYWRITE;
1634
1635 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1636out_fput:
1637 if (file)
1638 fput(file);
1639 return retval;
1640}
1641
1642SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1643 unsigned long, prot, unsigned long, flags,
1644 unsigned long, fd, unsigned long, pgoff)
1645{
1646 return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff);
1647}
1648
1649#ifdef __ARCH_WANT_SYS_OLD_MMAP
1650struct mmap_arg_struct {
1651 unsigned long addr;
1652 unsigned long len;
1653 unsigned long prot;
1654 unsigned long flags;
1655 unsigned long fd;
1656 unsigned long offset;
1657};
1658
1659SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1660{
1661 struct mmap_arg_struct a;
1662
1663 if (copy_from_user(&a, arg, sizeof(a)))
1664 return -EFAULT;
1665 if (offset_in_page(a.offset))
1666 return -EINVAL;
1667
1668 return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1669 a.offset >> PAGE_SHIFT);
1670}
1671#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1672
1673/*
1674 * Some shared mappings will want the pages marked read-only
1675 * to track write events. If so, we'll downgrade vm_page_prot
1676 * to the private version (using protection_map[] without the
1677 * VM_SHARED bit).
1678 */
1679int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot)
1680{
1681 vm_flags_t vm_flags = vma->vm_flags;
1682 const struct vm_operations_struct *vm_ops = vma->vm_ops;
1683
1684 /* If it was private or non-writable, the write bit is already clear */
1685 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1686 return 0;
1687
1688 /* The backer wishes to know when pages are first written to? */
1689 if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite))
1690 return 1;
1691
1692 /* The open routine did something to the protections that pgprot_modify
1693 * won't preserve? */
1694 if (pgprot_val(vm_page_prot) !=
1695 pgprot_val(vm_pgprot_modify(vm_page_prot, vm_flags)))
1696 return 0;
1697
1698 /* Do we need to track softdirty? */
1699 if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY))
1700 return 1;
1701
1702 /* Specialty mapping? */
1703 if (vm_flags & VM_PFNMAP)
1704 return 0;
1705
1706 /* Can the mapping track the dirty pages? */
1707 return vma->vm_file && vma->vm_file->f_mapping &&
1708 mapping_can_writeback(vma->vm_file->f_mapping);
1709}
1710
1711/*
1712 * We account for memory if it's a private writeable mapping,
1713 * not hugepages and VM_NORESERVE wasn't set.
1714 */
1715static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1716{
1717 /*
1718 * hugetlb has its own accounting separate from the core VM
1719 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1720 */
1721 if (file && is_file_hugepages(file))
1722 return 0;
1723
1724 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1725}
1726
1727unsigned long mmap_region(struct file *file, unsigned long addr,
1728 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
1729 struct list_head *uf)
1730{
1731 struct mm_struct *mm = current->mm;
1732 struct vm_area_struct *vma, *prev, *merge;
1733 int error;
1734 struct rb_node **rb_link, *rb_parent;
1735 unsigned long charged = 0;
1736
1737 /* Check against address space limit. */
1738 if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
1739 unsigned long nr_pages;
1740
1741 /*
1742 * MAP_FIXED may remove pages of mappings that intersects with
1743 * requested mapping. Account for the pages it would unmap.
1744 */
1745 nr_pages = count_vma_pages_range(mm, addr, addr + len);
1746
1747 if (!may_expand_vm(mm, vm_flags,
1748 (len >> PAGE_SHIFT) - nr_pages))
1749 return -ENOMEM;
1750 }
1751
1752 /* Clear old maps, set up prev, rb_link, rb_parent, and uf */
1753 if (munmap_vma_range(mm, addr, len, &prev, &rb_link, &rb_parent, uf))
1754 return -ENOMEM;
1755 /*
1756 * Private writable mapping: check memory availability
1757 */
1758 if (accountable_mapping(file, vm_flags)) {
1759 charged = len >> PAGE_SHIFT;
1760 if (security_vm_enough_memory_mm(mm, charged))
1761 return -ENOMEM;
1762 vm_flags |= VM_ACCOUNT;
1763 }
1764
1765 /*
1766 * Can we just expand an old mapping?
1767 */
1768 vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
1769 NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX);
1770 if (vma)
1771 goto out;
1772
1773 /*
1774 * Determine the object being mapped and call the appropriate
1775 * specific mapper. the address has already been validated, but
1776 * not unmapped, but the maps are removed from the list.
1777 */
1778 vma = vm_area_alloc(mm);
1779 if (!vma) {
1780 error = -ENOMEM;
1781 goto unacct_error;
1782 }
1783
1784 vma->vm_start = addr;
1785 vma->vm_end = addr + len;
1786 vma->vm_flags = vm_flags;
1787 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1788 vma->vm_pgoff = pgoff;
1789
1790 if (file) {
1791 if (vm_flags & VM_DENYWRITE) {
1792 error = deny_write_access(file);
1793 if (error)
1794 goto free_vma;
1795 }
1796 if (vm_flags & VM_SHARED) {
1797 error = mapping_map_writable(file->f_mapping);
1798 if (error)
1799 goto allow_write_and_free_vma;
1800 }
1801
1802 /* ->mmap() can change vma->vm_file, but must guarantee that
1803 * vma_link() below can deny write-access if VM_DENYWRITE is set
1804 * and map writably if VM_SHARED is set. This usually means the
1805 * new file must not have been exposed to user-space, yet.
1806 */
1807 vma->vm_file = get_file(file);
1808 error = call_mmap(file, vma);
1809 if (error)
1810 goto unmap_and_free_vma;
1811
1812 /* Can addr have changed??
1813 *
1814 * Answer: Yes, several device drivers can do it in their
1815 * f_op->mmap method. -DaveM
1816 * Bug: If addr is changed, prev, rb_link, rb_parent should
1817 * be updated for vma_link()
1818 */
1819 WARN_ON_ONCE(addr != vma->vm_start);
1820
1821 addr = vma->vm_start;
1822
1823 /* If vm_flags changed after call_mmap(), we should try merge vma again
1824 * as we may succeed this time.
1825 */
1826 if (unlikely(vm_flags != vma->vm_flags && prev)) {
1827 merge = vma_merge(mm, prev, vma->vm_start, vma->vm_end, vma->vm_flags,
1828 NULL, vma->vm_file, vma->vm_pgoff, NULL, NULL_VM_UFFD_CTX);
1829 if (merge) {
1830 /* ->mmap() can change vma->vm_file and fput the original file. So
1831 * fput the vma->vm_file here or we would add an extra fput for file
1832 * and cause general protection fault ultimately.
1833 */
1834 fput(vma->vm_file);
1835 vm_area_free(vma);
1836 vma = merge;
1837 /* Update vm_flags to pick up the change. */
1838 vm_flags = vma->vm_flags;
1839 goto unmap_writable;
1840 }
1841 }
1842
1843 vm_flags = vma->vm_flags;
1844 } else if (vm_flags & VM_SHARED) {
1845 error = shmem_zero_setup(vma);
1846 if (error)
1847 goto free_vma;
1848 } else {
1849 vma_set_anonymous(vma);
1850 }
1851
1852 /* Allow architectures to sanity-check the vm_flags */
1853 if (!arch_validate_flags(vma->vm_flags)) {
1854 error = -EINVAL;
1855 if (file)
1856 goto unmap_and_free_vma;
1857 else
1858 goto free_vma;
1859 }
1860
1861 vma_link(mm, vma, prev, rb_link, rb_parent);
1862 /* Once vma denies write, undo our temporary denial count */
1863 if (file) {
1864unmap_writable:
1865 if (vm_flags & VM_SHARED)
1866 mapping_unmap_writable(file->f_mapping);
1867 if (vm_flags & VM_DENYWRITE)
1868 allow_write_access(file);
1869 }
1870 file = vma->vm_file;
1871out:
1872 perf_event_mmap(vma);
1873
1874 vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
1875 if (vm_flags & VM_LOCKED) {
1876 if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) ||
1877 is_vm_hugetlb_page(vma) ||
1878 vma == get_gate_vma(current->mm))
1879 vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
1880 else
1881 mm->locked_vm += (len >> PAGE_SHIFT);
1882 }
1883
1884 if (file)
1885 uprobe_mmap(vma);
1886
1887 /*
1888 * New (or expanded) vma always get soft dirty status.
1889 * Otherwise user-space soft-dirty page tracker won't
1890 * be able to distinguish situation when vma area unmapped,
1891 * then new mapped in-place (which must be aimed as
1892 * a completely new data area).
1893 */
1894 vma->vm_flags |= VM_SOFTDIRTY;
1895
1896 vma_set_page_prot(vma);
1897
1898 return addr;
1899
1900unmap_and_free_vma:
1901 fput(vma->vm_file);
1902 vma->vm_file = NULL;
1903
1904 /* Undo any partial mapping done by a device driver. */
1905 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1906 charged = 0;
1907 if (vm_flags & VM_SHARED)
1908 mapping_unmap_writable(file->f_mapping);
1909allow_write_and_free_vma:
1910 if (vm_flags & VM_DENYWRITE)
1911 allow_write_access(file);
1912free_vma:
1913 vm_area_free(vma);
1914unacct_error:
1915 if (charged)
1916 vm_unacct_memory(charged);
1917 return error;
1918}
1919
1920static unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1921{
1922 /*
1923 * We implement the search by looking for an rbtree node that
1924 * immediately follows a suitable gap. That is,
1925 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1926 * - gap_end = vma->vm_start >= info->low_limit + length;
1927 * - gap_end - gap_start >= length
1928 */
1929
1930 struct mm_struct *mm = current->mm;
1931 struct vm_area_struct *vma;
1932 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1933
1934 /* Adjust search length to account for worst case alignment overhead */
1935 length = info->length + info->align_mask;
1936 if (length < info->length)
1937 return -ENOMEM;
1938
1939 /* Adjust search limits by the desired length */
1940 if (info->high_limit < length)
1941 return -ENOMEM;
1942 high_limit = info->high_limit - length;
1943
1944 if (info->low_limit > high_limit)
1945 return -ENOMEM;
1946 low_limit = info->low_limit + length;
1947
1948 /* Check if rbtree root looks promising */
1949 if (RB_EMPTY_ROOT(&mm->mm_rb))
1950 goto check_highest;
1951 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1952 if (vma->rb_subtree_gap < length)
1953 goto check_highest;
1954
1955 while (true) {
1956 /* Visit left subtree if it looks promising */
1957 gap_end = vm_start_gap(vma);
1958 if (gap_end >= low_limit && vma->vm_rb.rb_left) {
1959 struct vm_area_struct *left =
1960 rb_entry(vma->vm_rb.rb_left,
1961 struct vm_area_struct, vm_rb);
1962 if (left->rb_subtree_gap >= length) {
1963 vma = left;
1964 continue;
1965 }
1966 }
1967
1968 gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
1969check_current:
1970 /* Check if current node has a suitable gap */
1971 if (gap_start > high_limit)
1972 return -ENOMEM;
1973 if (gap_end >= low_limit &&
1974 gap_end > gap_start && gap_end - gap_start >= length)
1975 goto found;
1976
1977 /* Visit right subtree if it looks promising */
1978 if (vma->vm_rb.rb_right) {
1979 struct vm_area_struct *right =
1980 rb_entry(vma->vm_rb.rb_right,
1981 struct vm_area_struct, vm_rb);
1982 if (right->rb_subtree_gap >= length) {
1983 vma = right;
1984 continue;
1985 }
1986 }
1987
1988 /* Go back up the rbtree to find next candidate node */
1989 while (true) {
1990 struct rb_node *prev = &vma->vm_rb;
1991 if (!rb_parent(prev))
1992 goto check_highest;
1993 vma = rb_entry(rb_parent(prev),
1994 struct vm_area_struct, vm_rb);
1995 if (prev == vma->vm_rb.rb_left) {
1996 gap_start = vm_end_gap(vma->vm_prev);
1997 gap_end = vm_start_gap(vma);
1998 goto check_current;
1999 }
2000 }
2001 }
2002
2003check_highest:
2004 /* Check highest gap, which does not precede any rbtree node */
2005 gap_start = mm->highest_vm_end;
2006 gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */
2007 if (gap_start > high_limit)
2008 return -ENOMEM;
2009
2010found:
2011 /* We found a suitable gap. Clip it with the original low_limit. */
2012 if (gap_start < info->low_limit)
2013 gap_start = info->low_limit;
2014
2015 /* Adjust gap address to the desired alignment */
2016 gap_start += (info->align_offset - gap_start) & info->align_mask;
2017
2018 VM_BUG_ON(gap_start + info->length > info->high_limit);
2019 VM_BUG_ON(gap_start + info->length > gap_end);
2020 return gap_start;
2021}
2022
2023static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
2024{
2025 struct mm_struct *mm = current->mm;
2026 struct vm_area_struct *vma;
2027 unsigned long length, low_limit, high_limit, gap_start, gap_end;
2028
2029 /* Adjust search length to account for worst case alignment overhead */
2030 length = info->length + info->align_mask;
2031 if (length < info->length)
2032 return -ENOMEM;
2033
2034 /*
2035 * Adjust search limits by the desired length.
2036 * See implementation comment at top of unmapped_area().
2037 */
2038 gap_end = info->high_limit;
2039 if (gap_end < length)
2040 return -ENOMEM;
2041 high_limit = gap_end - length;
2042
2043 if (info->low_limit > high_limit)
2044 return -ENOMEM;
2045 low_limit = info->low_limit + length;
2046
2047 /* Check highest gap, which does not precede any rbtree node */
2048 gap_start = mm->highest_vm_end;
2049 if (gap_start <= high_limit)
2050 goto found_highest;
2051
2052 /* Check if rbtree root looks promising */
2053 if (RB_EMPTY_ROOT(&mm->mm_rb))
2054 return -ENOMEM;
2055 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
2056 if (vma->rb_subtree_gap < length)
2057 return -ENOMEM;
2058
2059 while (true) {
2060 /* Visit right subtree if it looks promising */
2061 gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
2062 if (gap_start <= high_limit && vma->vm_rb.rb_right) {
2063 struct vm_area_struct *right =
2064 rb_entry(vma->vm_rb.rb_right,
2065 struct vm_area_struct, vm_rb);
2066 if (right->rb_subtree_gap >= length) {
2067 vma = right;
2068 continue;
2069 }
2070 }
2071
2072check_current:
2073 /* Check if current node has a suitable gap */
2074 gap_end = vm_start_gap(vma);
2075 if (gap_end < low_limit)
2076 return -ENOMEM;
2077 if (gap_start <= high_limit &&
2078 gap_end > gap_start && gap_end - gap_start >= length)
2079 goto found;
2080
2081 /* Visit left subtree if it looks promising */
2082 if (vma->vm_rb.rb_left) {
2083 struct vm_area_struct *left =
2084 rb_entry(vma->vm_rb.rb_left,
2085 struct vm_area_struct, vm_rb);
2086 if (left->rb_subtree_gap >= length) {
2087 vma = left;
2088 continue;
2089 }
2090 }
2091
2092 /* Go back up the rbtree to find next candidate node */
2093 while (true) {
2094 struct rb_node *prev = &vma->vm_rb;
2095 if (!rb_parent(prev))
2096 return -ENOMEM;
2097 vma = rb_entry(rb_parent(prev),
2098 struct vm_area_struct, vm_rb);
2099 if (prev == vma->vm_rb.rb_right) {
2100 gap_start = vma->vm_prev ?
2101 vm_end_gap(vma->vm_prev) : 0;
2102 goto check_current;
2103 }
2104 }
2105 }
2106
2107found:
2108 /* We found a suitable gap. Clip it with the original high_limit. */
2109 if (gap_end > info->high_limit)
2110 gap_end = info->high_limit;
2111
2112found_highest:
2113 /* Compute highest gap address at the desired alignment */
2114 gap_end -= info->length;
2115 gap_end -= (gap_end - info->align_offset) & info->align_mask;
2116
2117 VM_BUG_ON(gap_end < info->low_limit);
2118 VM_BUG_ON(gap_end < gap_start);
2119 return gap_end;
2120}
2121
2122/*
2123 * Search for an unmapped address range.
2124 *
2125 * We are looking for a range that:
2126 * - does not intersect with any VMA;
2127 * - is contained within the [low_limit, high_limit) interval;
2128 * - is at least the desired size.
2129 * - satisfies (begin_addr & align_mask) == (align_offset & align_mask)
2130 */
2131unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info)
2132{
2133 unsigned long addr;
2134
2135 if (info->flags & VM_UNMAPPED_AREA_TOPDOWN)
2136 addr = unmapped_area_topdown(info);
2137 else
2138 addr = unmapped_area(info);
2139
2140 trace_vm_unmapped_area(addr, info);
2141 return addr;
2142}
2143
2144#ifndef arch_get_mmap_end
2145#define arch_get_mmap_end(addr) (TASK_SIZE)
2146#endif
2147
2148#ifndef arch_get_mmap_base
2149#define arch_get_mmap_base(addr, base) (base)
2150#endif
2151
2152/* Get an address range which is currently unmapped.
2153 * For shmat() with addr=0.
2154 *
2155 * Ugly calling convention alert:
2156 * Return value with the low bits set means error value,
2157 * ie
2158 * if (ret & ~PAGE_MASK)
2159 * error = ret;
2160 *
2161 * This function "knows" that -ENOMEM has the bits set.
2162 */
2163#ifndef HAVE_ARCH_UNMAPPED_AREA
2164unsigned long
2165arch_get_unmapped_area(struct file *filp, unsigned long addr,
2166 unsigned long len, unsigned long pgoff, unsigned long flags)
2167{
2168 struct mm_struct *mm = current->mm;
2169 struct vm_area_struct *vma, *prev;
2170 struct vm_unmapped_area_info info;
2171 const unsigned long mmap_end = arch_get_mmap_end(addr);
2172
2173 if (len > mmap_end - mmap_min_addr)
2174 return -ENOMEM;
2175
2176 if (flags & MAP_FIXED)
2177 return addr;
2178
2179 if (addr) {
2180 addr = PAGE_ALIGN(addr);
2181 vma = find_vma_prev(mm, addr, &prev);
2182 if (mmap_end - len >= addr && addr >= mmap_min_addr &&
2183 (!vma || addr + len <= vm_start_gap(vma)) &&
2184 (!prev || addr >= vm_end_gap(prev)))
2185 return addr;
2186 }
2187
2188 info.flags = 0;
2189 info.length = len;
2190 info.low_limit = mm->mmap_base;
2191 info.high_limit = mmap_end;
2192 info.align_mask = 0;
2193 info.align_offset = 0;
2194 return vm_unmapped_area(&info);
2195}
2196#endif
2197
2198/*
2199 * This mmap-allocator allocates new areas top-down from below the
2200 * stack's low limit (the base):
2201 */
2202#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
2203unsigned long
2204arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
2205 unsigned long len, unsigned long pgoff,
2206 unsigned long flags)
2207{
2208 struct vm_area_struct *vma, *prev;
2209 struct mm_struct *mm = current->mm;
2210 struct vm_unmapped_area_info info;
2211 const unsigned long mmap_end = arch_get_mmap_end(addr);
2212
2213 /* requested length too big for entire address space */
2214 if (len > mmap_end - mmap_min_addr)
2215 return -ENOMEM;
2216
2217 if (flags & MAP_FIXED)
2218 return addr;
2219
2220 /* requesting a specific address */
2221 if (addr) {
2222 addr = PAGE_ALIGN(addr);
2223 vma = find_vma_prev(mm, addr, &prev);
2224 if (mmap_end - len >= addr && addr >= mmap_min_addr &&
2225 (!vma || addr + len <= vm_start_gap(vma)) &&
2226 (!prev || addr >= vm_end_gap(prev)))
2227 return addr;
2228 }
2229
2230 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
2231 info.length = len;
2232 info.low_limit = max(PAGE_SIZE, mmap_min_addr);
2233 info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
2234 info.align_mask = 0;
2235 info.align_offset = 0;
2236 addr = vm_unmapped_area(&info);
2237
2238 /*
2239 * A failed mmap() very likely causes application failure,
2240 * so fall back to the bottom-up function here. This scenario
2241 * can happen with large stack limits and large mmap()
2242 * allocations.
2243 */
2244 if (offset_in_page(addr)) {
2245 VM_BUG_ON(addr != -ENOMEM);
2246 info.flags = 0;
2247 info.low_limit = TASK_UNMAPPED_BASE;
2248 info.high_limit = mmap_end;
2249 addr = vm_unmapped_area(&info);
2250 }
2251
2252 return addr;
2253}
2254#endif
2255
2256unsigned long
2257get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
2258 unsigned long pgoff, unsigned long flags)
2259{
2260 unsigned long (*get_area)(struct file *, unsigned long,
2261 unsigned long, unsigned long, unsigned long);
2262
2263 unsigned long error = arch_mmap_check(addr, len, flags);
2264 if (error)
2265 return error;
2266
2267 /* Careful about overflows.. */
2268 if (len > TASK_SIZE)
2269 return -ENOMEM;
2270
2271 get_area = current->mm->get_unmapped_area;
2272 if (file) {
2273 if (file->f_op->get_unmapped_area)
2274 get_area = file->f_op->get_unmapped_area;
2275 } else if (flags & MAP_SHARED) {
2276 /*
2277 * mmap_region() will call shmem_zero_setup() to create a file,
2278 * so use shmem's get_unmapped_area in case it can be huge.
2279 * do_mmap() will clear pgoff, so match alignment.
2280 */
2281 pgoff = 0;
2282 get_area = shmem_get_unmapped_area;
2283 }
2284
2285 addr = get_area(file, addr, len, pgoff, flags);
2286 if (IS_ERR_VALUE(addr))
2287 return addr;
2288
2289 if (addr > TASK_SIZE - len)
2290 return -ENOMEM;
2291 if (offset_in_page(addr))
2292 return -EINVAL;
2293
2294 error = security_mmap_addr(addr);
2295 return error ? error : addr;
2296}
2297
2298EXPORT_SYMBOL(get_unmapped_area);
2299
2300/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
2301struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
2302{
2303 struct rb_node *rb_node;
2304 struct vm_area_struct *vma;
2305
2306 /* Check the cache first. */
2307 vma = vmacache_find(mm, addr);
2308 if (likely(vma))
2309 return vma;
2310
2311 rb_node = mm->mm_rb.rb_node;
2312
2313 while (rb_node) {
2314 struct vm_area_struct *tmp;
2315
2316 tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2317
2318 if (tmp->vm_end > addr) {
2319 vma = tmp;
2320 if (tmp->vm_start <= addr)
2321 break;
2322 rb_node = rb_node->rb_left;
2323 } else
2324 rb_node = rb_node->rb_right;
2325 }
2326
2327 if (vma)
2328 vmacache_update(addr, vma);
2329 return vma;
2330}
2331
2332EXPORT_SYMBOL(find_vma);
2333
2334/*
2335 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
2336 */
2337struct vm_area_struct *
2338find_vma_prev(struct mm_struct *mm, unsigned long addr,
2339 struct vm_area_struct **pprev)
2340{
2341 struct vm_area_struct *vma;
2342
2343 vma = find_vma(mm, addr);
2344 if (vma) {
2345 *pprev = vma->vm_prev;
2346 } else {
2347 struct rb_node *rb_node = rb_last(&mm->mm_rb);
2348
2349 *pprev = rb_node ? rb_entry(rb_node, struct vm_area_struct, vm_rb) : NULL;
2350 }
2351 return vma;
2352}
2353
2354/*
2355 * Verify that the stack growth is acceptable and
2356 * update accounting. This is shared with both the
2357 * grow-up and grow-down cases.
2358 */
2359static int acct_stack_growth(struct vm_area_struct *vma,
2360 unsigned long size, unsigned long grow)
2361{
2362 struct mm_struct *mm = vma->vm_mm;
2363 unsigned long new_start;
2364
2365 /* address space limit tests */
2366 if (!may_expand_vm(mm, vma->vm_flags, grow))
2367 return -ENOMEM;
2368
2369 /* Stack limit test */
2370 if (size > rlimit(RLIMIT_STACK))
2371 return -ENOMEM;
2372
2373 /* mlock limit tests */
2374 if (vma->vm_flags & VM_LOCKED) {
2375 unsigned long locked;
2376 unsigned long limit;
2377 locked = mm->locked_vm + grow;
2378 limit = rlimit(RLIMIT_MEMLOCK);
2379 limit >>= PAGE_SHIFT;
2380 if (locked > limit && !capable(CAP_IPC_LOCK))
2381 return -ENOMEM;
2382 }
2383
2384 /* Check to ensure the stack will not grow into a hugetlb-only region */
2385 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
2386 vma->vm_end - size;
2387 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
2388 return -EFAULT;
2389
2390 /*
2391 * Overcommit.. This must be the final test, as it will
2392 * update security statistics.
2393 */
2394 if (security_vm_enough_memory_mm(mm, grow))
2395 return -ENOMEM;
2396
2397 return 0;
2398}
2399
2400#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2401/*
2402 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2403 * vma is the last one with address > vma->vm_end. Have to extend vma.
2404 */
2405int expand_upwards(struct vm_area_struct *vma, unsigned long address)
2406{
2407 struct mm_struct *mm = vma->vm_mm;
2408 struct vm_area_struct *next;
2409 unsigned long gap_addr;
2410 int error = 0;
2411
2412 if (!(vma->vm_flags & VM_GROWSUP))
2413 return -EFAULT;
2414
2415 /* Guard against exceeding limits of the address space. */
2416 address &= PAGE_MASK;
2417 if (address >= (TASK_SIZE & PAGE_MASK))
2418 return -ENOMEM;
2419 address += PAGE_SIZE;
2420
2421 /* Enforce stack_guard_gap */
2422 gap_addr = address + stack_guard_gap;
2423
2424 /* Guard against overflow */
2425 if (gap_addr < address || gap_addr > TASK_SIZE)
2426 gap_addr = TASK_SIZE;
2427
2428 next = vma->vm_next;
2429 if (next && next->vm_start < gap_addr && vma_is_accessible(next)) {
2430 if (!(next->vm_flags & VM_GROWSUP))
2431 return -ENOMEM;
2432 /* Check that both stack segments have the same anon_vma? */
2433 }
2434
2435 /* We must make sure the anon_vma is allocated. */
2436 if (unlikely(anon_vma_prepare(vma)))
2437 return -ENOMEM;
2438
2439 /*
2440 * vma->vm_start/vm_end cannot change under us because the caller
2441 * is required to hold the mmap_lock in read mode. We need the
2442 * anon_vma lock to serialize against concurrent expand_stacks.
2443 */
2444 anon_vma_lock_write(vma->anon_vma);
2445
2446 /* Somebody else might have raced and expanded it already */
2447 if (address > vma->vm_end) {
2448 unsigned long size, grow;
2449
2450 size = address - vma->vm_start;
2451 grow = (address - vma->vm_end) >> PAGE_SHIFT;
2452
2453 error = -ENOMEM;
2454 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2455 error = acct_stack_growth(vma, size, grow);
2456 if (!error) {
2457 /*
2458 * vma_gap_update() doesn't support concurrent
2459 * updates, but we only hold a shared mmap_lock
2460 * lock here, so we need to protect against
2461 * concurrent vma expansions.
2462 * anon_vma_lock_write() doesn't help here, as
2463 * we don't guarantee that all growable vmas
2464 * in a mm share the same root anon vma.
2465 * So, we reuse mm->page_table_lock to guard
2466 * against concurrent vma expansions.
2467 */
2468 spin_lock(&mm->page_table_lock);
2469 if (vma->vm_flags & VM_LOCKED)
2470 mm->locked_vm += grow;
2471 vm_stat_account(mm, vma->vm_flags, grow);
2472 anon_vma_interval_tree_pre_update_vma(vma);
2473 vma->vm_end = address;
2474 anon_vma_interval_tree_post_update_vma(vma);
2475 if (vma->vm_next)
2476 vma_gap_update(vma->vm_next);
2477 else
2478 mm->highest_vm_end = vm_end_gap(vma);
2479 spin_unlock(&mm->page_table_lock);
2480
2481 perf_event_mmap(vma);
2482 }
2483 }
2484 }
2485 anon_vma_unlock_write(vma->anon_vma);
2486 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2487 validate_mm(mm);
2488 return error;
2489}
2490#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2491
2492/*
2493 * vma is the first one with address < vma->vm_start. Have to extend vma.
2494 */
2495int expand_downwards(struct vm_area_struct *vma,
2496 unsigned long address)
2497{
2498 struct mm_struct *mm = vma->vm_mm;
2499 struct vm_area_struct *prev;
2500 int error = 0;
2501
2502 address &= PAGE_MASK;
2503 if (address < mmap_min_addr)
2504 return -EPERM;
2505
2506 /* Enforce stack_guard_gap */
2507 prev = vma->vm_prev;
2508 /* Check that both stack segments have the same anon_vma? */
2509 if (prev && !(prev->vm_flags & VM_GROWSDOWN) &&
2510 vma_is_accessible(prev)) {
2511 if (address - prev->vm_end < stack_guard_gap)
2512 return -ENOMEM;
2513 }
2514
2515 /* We must make sure the anon_vma is allocated. */
2516 if (unlikely(anon_vma_prepare(vma)))
2517 return -ENOMEM;
2518
2519 /*
2520 * vma->vm_start/vm_end cannot change under us because the caller
2521 * is required to hold the mmap_lock in read mode. We need the
2522 * anon_vma lock to serialize against concurrent expand_stacks.
2523 */
2524 anon_vma_lock_write(vma->anon_vma);
2525
2526 /* Somebody else might have raced and expanded it already */
2527 if (address < vma->vm_start) {
2528 unsigned long size, grow;
2529
2530 size = vma->vm_end - address;
2531 grow = (vma->vm_start - address) >> PAGE_SHIFT;
2532
2533 error = -ENOMEM;
2534 if (grow <= vma->vm_pgoff) {
2535 error = acct_stack_growth(vma, size, grow);
2536 if (!error) {
2537 /*
2538 * vma_gap_update() doesn't support concurrent
2539 * updates, but we only hold a shared mmap_lock
2540 * lock here, so we need to protect against
2541 * concurrent vma expansions.
2542 * anon_vma_lock_write() doesn't help here, as
2543 * we don't guarantee that all growable vmas
2544 * in a mm share the same root anon vma.
2545 * So, we reuse mm->page_table_lock to guard
2546 * against concurrent vma expansions.
2547 */
2548 spin_lock(&mm->page_table_lock);
2549 if (vma->vm_flags & VM_LOCKED)
2550 mm->locked_vm += grow;
2551 vm_stat_account(mm, vma->vm_flags, grow);
2552 anon_vma_interval_tree_pre_update_vma(vma);
2553 vma->vm_start = address;
2554 vma->vm_pgoff -= grow;
2555 anon_vma_interval_tree_post_update_vma(vma);
2556 vma_gap_update(vma);
2557 spin_unlock(&mm->page_table_lock);
2558
2559 perf_event_mmap(vma);
2560 }
2561 }
2562 }
2563 anon_vma_unlock_write(vma->anon_vma);
2564 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2565 validate_mm(mm);
2566 return error;
2567}
2568
2569/* enforced gap between the expanding stack and other mappings. */
2570unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
2571
2572static int __init cmdline_parse_stack_guard_gap(char *p)
2573{
2574 unsigned long val;
2575 char *endptr;
2576
2577 val = simple_strtoul(p, &endptr, 10);
2578 if (!*endptr)
2579 stack_guard_gap = val << PAGE_SHIFT;
2580
2581 return 0;
2582}
2583__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
2584
2585#ifdef CONFIG_STACK_GROWSUP
2586int expand_stack(struct vm_area_struct *vma, unsigned long address)
2587{
2588 return expand_upwards(vma, address);
2589}
2590
2591struct vm_area_struct *
2592find_extend_vma(struct mm_struct *mm, unsigned long addr)
2593{
2594 struct vm_area_struct *vma, *prev;
2595
2596 addr &= PAGE_MASK;
2597 vma = find_vma_prev(mm, addr, &prev);
2598 if (vma && (vma->vm_start <= addr))
2599 return vma;
2600 /* don't alter vm_end if the coredump is running */
2601 if (!prev || expand_stack(prev, addr))
2602 return NULL;
2603 if (prev->vm_flags & VM_LOCKED)
2604 populate_vma_page_range(prev, addr, prev->vm_end, NULL);
2605 return prev;
2606}
2607#else
2608int expand_stack(struct vm_area_struct *vma, unsigned long address)
2609{
2610 return expand_downwards(vma, address);
2611}
2612
2613struct vm_area_struct *
2614find_extend_vma(struct mm_struct *mm, unsigned long addr)
2615{
2616 struct vm_area_struct *vma;
2617 unsigned long start;
2618
2619 addr &= PAGE_MASK;
2620 vma = find_vma(mm, addr);
2621 if (!vma)
2622 return NULL;
2623 if (vma->vm_start <= addr)
2624 return vma;
2625 if (!(vma->vm_flags & VM_GROWSDOWN))
2626 return NULL;
2627 start = vma->vm_start;
2628 if (expand_stack(vma, addr))
2629 return NULL;
2630 if (vma->vm_flags & VM_LOCKED)
2631 populate_vma_page_range(vma, addr, start, NULL);
2632 return vma;
2633}
2634#endif
2635
2636EXPORT_SYMBOL_GPL(find_extend_vma);
2637
2638/*
2639 * Ok - we have the memory areas we should free on the vma list,
2640 * so release them, and do the vma updates.
2641 *
2642 * Called with the mm semaphore held.
2643 */
2644static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
2645{
2646 unsigned long nr_accounted = 0;
2647
2648 /* Update high watermark before we lower total_vm */
2649 update_hiwater_vm(mm);
2650 do {
2651 long nrpages = vma_pages(vma);
2652
2653 if (vma->vm_flags & VM_ACCOUNT)
2654 nr_accounted += nrpages;
2655 vm_stat_account(mm, vma->vm_flags, -nrpages);
2656 vma = remove_vma(vma);
2657 } while (vma);
2658 vm_unacct_memory(nr_accounted);
2659 validate_mm(mm);
2660}
2661
2662/*
2663 * Get rid of page table information in the indicated region.
2664 *
2665 * Called with the mm semaphore held.
2666 */
2667static void unmap_region(struct mm_struct *mm,
2668 struct vm_area_struct *vma, struct vm_area_struct *prev,
2669 unsigned long start, unsigned long end)
2670{
2671 struct vm_area_struct *next = vma_next(mm, prev);
2672 struct mmu_gather tlb;
2673
2674 lru_add_drain();
2675 tlb_gather_mmu(&tlb, mm);
2676 update_hiwater_rss(mm);
2677 unmap_vmas(&tlb, vma, start, end);
2678 free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2679 next ? next->vm_start : USER_PGTABLES_CEILING);
2680 tlb_finish_mmu(&tlb);
2681}
2682
2683/*
2684 * Create a list of vma's touched by the unmap, removing them from the mm's
2685 * vma list as we go..
2686 */
2687static bool
2688detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
2689 struct vm_area_struct *prev, unsigned long end)
2690{
2691 struct vm_area_struct **insertion_point;
2692 struct vm_area_struct *tail_vma = NULL;
2693
2694 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2695 vma->vm_prev = NULL;
2696 do {
2697 vma_rb_erase(vma, &mm->mm_rb);
2698 mm->map_count--;
2699 tail_vma = vma;
2700 vma = vma->vm_next;
2701 } while (vma && vma->vm_start < end);
2702 *insertion_point = vma;
2703 if (vma) {
2704 vma->vm_prev = prev;
2705 vma_gap_update(vma);
2706 } else
2707 mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
2708 tail_vma->vm_next = NULL;
2709
2710 /* Kill the cache */
2711 vmacache_invalidate(mm);
2712
2713 /*
2714 * Do not downgrade mmap_lock if we are next to VM_GROWSDOWN or
2715 * VM_GROWSUP VMA. Such VMAs can change their size under
2716 * down_read(mmap_lock) and collide with the VMA we are about to unmap.
2717 */
2718 if (vma && (vma->vm_flags & VM_GROWSDOWN))
2719 return false;
2720 if (prev && (prev->vm_flags & VM_GROWSUP))
2721 return false;
2722 return true;
2723}
2724
2725/*
2726 * __split_vma() bypasses sysctl_max_map_count checking. We use this where it
2727 * has already been checked or doesn't make sense to fail.
2728 */
2729int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2730 unsigned long addr, int new_below)
2731{
2732 struct vm_area_struct *new;
2733 int err;
2734
2735 if (vma->vm_ops && vma->vm_ops->may_split) {
2736 err = vma->vm_ops->may_split(vma, addr);
2737 if (err)
2738 return err;
2739 }
2740
2741 new = vm_area_dup(vma);
2742 if (!new)
2743 return -ENOMEM;
2744
2745 if (new_below)
2746 new->vm_end = addr;
2747 else {
2748 new->vm_start = addr;
2749 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2750 }
2751
2752 err = vma_dup_policy(vma, new);
2753 if (err)
2754 goto out_free_vma;
2755
2756 err = anon_vma_clone(new, vma);
2757 if (err)
2758 goto out_free_mpol;
2759
2760 if (new->vm_file)
2761 get_file(new->vm_file);
2762
2763 if (new->vm_ops && new->vm_ops->open)
2764 new->vm_ops->open(new);
2765
2766 if (new_below)
2767 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2768 ((addr - new->vm_start) >> PAGE_SHIFT), new);
2769 else
2770 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2771
2772 /* Success. */
2773 if (!err)
2774 return 0;
2775
2776 /* Clean everything up if vma_adjust failed. */
2777 if (new->vm_ops && new->vm_ops->close)
2778 new->vm_ops->close(new);
2779 if (new->vm_file)
2780 fput(new->vm_file);
2781 unlink_anon_vmas(new);
2782 out_free_mpol:
2783 mpol_put(vma_policy(new));
2784 out_free_vma:
2785 vm_area_free(new);
2786 return err;
2787}
2788
2789/*
2790 * Split a vma into two pieces at address 'addr', a new vma is allocated
2791 * either for the first part or the tail.
2792 */
2793int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2794 unsigned long addr, int new_below)
2795{
2796 if (mm->map_count >= sysctl_max_map_count)
2797 return -ENOMEM;
2798
2799 return __split_vma(mm, vma, addr, new_below);
2800}
2801
2802static inline void
2803unlock_range(struct vm_area_struct *start, unsigned long limit)
2804{
2805 struct mm_struct *mm = start->vm_mm;
2806 struct vm_area_struct *tmp = start;
2807
2808 while (tmp && tmp->vm_start < limit) {
2809 if (tmp->vm_flags & VM_LOCKED) {
2810 mm->locked_vm -= vma_pages(tmp);
2811 munlock_vma_pages_all(tmp);
2812 }
2813
2814 tmp = tmp->vm_next;
2815 }
2816}
2817
2818/* Munmap is split into 2 main parts -- this part which finds
2819 * what needs doing, and the areas themselves, which do the
2820 * work. This now handles partial unmappings.
2821 * Jeremy Fitzhardinge <jeremy@goop.org>
2822 */
2823int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
2824 struct list_head *uf, bool downgrade)
2825{
2826 unsigned long end;
2827 struct vm_area_struct *vma, *prev, *last;
2828
2829 if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
2830 return -EINVAL;
2831
2832 len = PAGE_ALIGN(len);
2833 end = start + len;
2834 if (len == 0)
2835 return -EINVAL;
2836
2837 /*
2838 * arch_unmap() might do unmaps itself. It must be called
2839 * and finish any rbtree manipulation before this code
2840 * runs and also starts to manipulate the rbtree.
2841 */
2842 arch_unmap(mm, start, end);
2843
2844 /* Find the first overlapping VMA where start < vma->vm_end */
2845 vma = find_vma_intersection(mm, start, end);
2846 if (!vma)
2847 return 0;
2848 prev = vma->vm_prev;
2849
2850 /*
2851 * If we need to split any vma, do it now to save pain later.
2852 *
2853 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2854 * unmapped vm_area_struct will remain in use: so lower split_vma
2855 * places tmp vma above, and higher split_vma places tmp vma below.
2856 */
2857 if (start > vma->vm_start) {
2858 int error;
2859
2860 /*
2861 * Make sure that map_count on return from munmap() will
2862 * not exceed its limit; but let map_count go just above
2863 * its limit temporarily, to help free resources as expected.
2864 */
2865 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2866 return -ENOMEM;
2867
2868 error = __split_vma(mm, vma, start, 0);
2869 if (error)
2870 return error;
2871 prev = vma;
2872 }
2873
2874 /* Does it split the last one? */
2875 last = find_vma(mm, end);
2876 if (last && end > last->vm_start) {
2877 int error = __split_vma(mm, last, end, 1);
2878 if (error)
2879 return error;
2880 }
2881 vma = vma_next(mm, prev);
2882
2883 if (unlikely(uf)) {
2884 /*
2885 * If userfaultfd_unmap_prep returns an error the vmas
2886 * will remain split, but userland will get a
2887 * highly unexpected error anyway. This is no
2888 * different than the case where the first of the two
2889 * __split_vma fails, but we don't undo the first
2890 * split, despite we could. This is unlikely enough
2891 * failure that it's not worth optimizing it for.
2892 */
2893 int error = userfaultfd_unmap_prep(vma, start, end, uf);
2894 if (error)
2895 return error;
2896 }
2897
2898 /*
2899 * unlock any mlock()ed ranges before detaching vmas
2900 */
2901 if (mm->locked_vm)
2902 unlock_range(vma, end);
2903
2904 /* Detach vmas from rbtree */
2905 if (!detach_vmas_to_be_unmapped(mm, vma, prev, end))
2906 downgrade = false;
2907
2908 if (downgrade)
2909 mmap_write_downgrade(mm);
2910
2911 unmap_region(mm, vma, prev, start, end);
2912
2913 /* Fix up all other VM information */
2914 remove_vma_list(mm, vma);
2915
2916 return downgrade ? 1 : 0;
2917}
2918
2919int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
2920 struct list_head *uf)
2921{
2922 return __do_munmap(mm, start, len, uf, false);
2923}
2924
2925static int __vm_munmap(unsigned long start, size_t len, bool downgrade)
2926{
2927 int ret;
2928 struct mm_struct *mm = current->mm;
2929 LIST_HEAD(uf);
2930
2931 if (mmap_write_lock_killable(mm))
2932 return -EINTR;
2933
2934 ret = __do_munmap(mm, start, len, &uf, downgrade);
2935 /*
2936 * Returning 1 indicates mmap_lock is downgraded.
2937 * But 1 is not legal return value of vm_munmap() and munmap(), reset
2938 * it to 0 before return.
2939 */
2940 if (ret == 1) {
2941 mmap_read_unlock(mm);
2942 ret = 0;
2943 } else
2944 mmap_write_unlock(mm);
2945
2946 userfaultfd_unmap_complete(mm, &uf);
2947 return ret;
2948}
2949
2950int vm_munmap(unsigned long start, size_t len)
2951{
2952 return __vm_munmap(start, len, false);
2953}
2954EXPORT_SYMBOL(vm_munmap);
2955
2956SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2957{
2958 addr = untagged_addr(addr);
2959 profile_munmap(addr);
2960 return __vm_munmap(addr, len, true);
2961}
2962
2963
2964/*
2965 * Emulation of deprecated remap_file_pages() syscall.
2966 */
2967SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
2968 unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
2969{
2970
2971 struct mm_struct *mm = current->mm;
2972 struct vm_area_struct *vma;
2973 unsigned long populate = 0;
2974 unsigned long ret = -EINVAL;
2975 struct file *file;
2976
2977 pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.rst.\n",
2978 current->comm, current->pid);
2979
2980 if (prot)
2981 return ret;
2982 start = start & PAGE_MASK;
2983 size = size & PAGE_MASK;
2984
2985 if (start + size <= start)
2986 return ret;
2987
2988 /* Does pgoff wrap? */
2989 if (pgoff + (size >> PAGE_SHIFT) < pgoff)
2990 return ret;
2991
2992 if (mmap_write_lock_killable(mm))
2993 return -EINTR;
2994
2995 vma = find_vma(mm, start);
2996
2997 if (!vma || !(vma->vm_flags & VM_SHARED))
2998 goto out;
2999
3000 if (start < vma->vm_start)
3001 goto out;
3002
3003 if (start + size > vma->vm_end) {
3004 struct vm_area_struct *next;
3005
3006 for (next = vma->vm_next; next; next = next->vm_next) {
3007 /* hole between vmas ? */
3008 if (next->vm_start != next->vm_prev->vm_end)
3009 goto out;
3010
3011 if (next->vm_file != vma->vm_file)
3012 goto out;
3013
3014 if (next->vm_flags != vma->vm_flags)
3015 goto out;
3016
3017 if (start + size <= next->vm_end)
3018 break;
3019 }
3020
3021 if (!next)
3022 goto out;
3023 }
3024
3025 prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
3026 prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
3027 prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
3028
3029 flags &= MAP_NONBLOCK;
3030 flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
3031 if (vma->vm_flags & VM_LOCKED)
3032 flags |= MAP_LOCKED;
3033
3034 file = get_file(vma->vm_file);
3035 ret = do_mmap(vma->vm_file, start, size,
3036 prot, flags, pgoff, &populate, NULL);
3037 fput(file);
3038out:
3039 mmap_write_unlock(mm);
3040 if (populate)
3041 mm_populate(ret, populate);
3042 if (!IS_ERR_VALUE(ret))
3043 ret = 0;
3044 return ret;
3045}
3046
3047/*
3048 * this is really a simplified "do_mmap". it only handles
3049 * anonymous maps. eventually we may be able to do some
3050 * brk-specific accounting here.
3051 */
3052static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long flags, struct list_head *uf)
3053{
3054 struct mm_struct *mm = current->mm;
3055 struct vm_area_struct *vma, *prev;
3056 struct rb_node **rb_link, *rb_parent;
3057 pgoff_t pgoff = addr >> PAGE_SHIFT;
3058 int error;
3059 unsigned long mapped_addr;
3060
3061 /* Until we need other flags, refuse anything except VM_EXEC. */
3062 if ((flags & (~VM_EXEC)) != 0)
3063 return -EINVAL;
3064 flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
3065
3066 mapped_addr = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
3067 if (IS_ERR_VALUE(mapped_addr))
3068 return mapped_addr;
3069
3070 error = mlock_future_check(mm, mm->def_flags, len);
3071 if (error)
3072 return error;
3073
3074 /* Clear old maps, set up prev, rb_link, rb_parent, and uf */
3075 if (munmap_vma_range(mm, addr, len, &prev, &rb_link, &rb_parent, uf))
3076 return -ENOMEM;
3077
3078 /* Check against address space limits *after* clearing old maps... */
3079 if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))
3080 return -ENOMEM;
3081
3082 if (mm->map_count > sysctl_max_map_count)
3083 return -ENOMEM;
3084
3085 if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
3086 return -ENOMEM;
3087
3088 /* Can we just expand an old private anonymous mapping? */
3089 vma = vma_merge(mm, prev, addr, addr + len, flags,
3090 NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX);
3091 if (vma)
3092 goto out;
3093
3094 /*
3095 * create a vma struct for an anonymous mapping
3096 */
3097 vma = vm_area_alloc(mm);
3098 if (!vma) {
3099 vm_unacct_memory(len >> PAGE_SHIFT);
3100 return -ENOMEM;
3101 }
3102
3103 vma_set_anonymous(vma);
3104 vma->vm_start = addr;
3105 vma->vm_end = addr + len;
3106 vma->vm_pgoff = pgoff;
3107 vma->vm_flags = flags;
3108 vma->vm_page_prot = vm_get_page_prot(flags);
3109 vma_link(mm, vma, prev, rb_link, rb_parent);
3110out:
3111 perf_event_mmap(vma);
3112 mm->total_vm += len >> PAGE_SHIFT;
3113 mm->data_vm += len >> PAGE_SHIFT;
3114 if (flags & VM_LOCKED)
3115 mm->locked_vm += (len >> PAGE_SHIFT);
3116 vma->vm_flags |= VM_SOFTDIRTY;
3117 return 0;
3118}
3119
3120int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
3121{
3122 struct mm_struct *mm = current->mm;
3123 unsigned long len;
3124 int ret;
3125 bool populate;
3126 LIST_HEAD(uf);
3127
3128 len = PAGE_ALIGN(request);
3129 if (len < request)
3130 return -ENOMEM;
3131 if (!len)
3132 return 0;
3133
3134 if (mmap_write_lock_killable(mm))
3135 return -EINTR;
3136
3137 ret = do_brk_flags(addr, len, flags, &uf);
3138 populate = ((mm->def_flags & VM_LOCKED) != 0);
3139 mmap_write_unlock(mm);
3140 userfaultfd_unmap_complete(mm, &uf);
3141 if (populate && !ret)
3142 mm_populate(addr, len);
3143 return ret;
3144}
3145EXPORT_SYMBOL(vm_brk_flags);
3146
3147int vm_brk(unsigned long addr, unsigned long len)
3148{
3149 return vm_brk_flags(addr, len, 0);
3150}
3151EXPORT_SYMBOL(vm_brk);
3152
3153/* Release all mmaps. */
3154void exit_mmap(struct mm_struct *mm)
3155{
3156 struct mmu_gather tlb;
3157 struct vm_area_struct *vma;
3158 unsigned long nr_accounted = 0;
3159
3160 /* mm's last user has gone, and its about to be pulled down */
3161 mmu_notifier_release(mm);
3162
3163 if (unlikely(mm_is_oom_victim(mm))) {
3164 /*
3165 * Manually reap the mm to free as much memory as possible.
3166 * Then, as the oom reaper does, set MMF_OOM_SKIP to disregard
3167 * this mm from further consideration. Taking mm->mmap_lock for
3168 * write after setting MMF_OOM_SKIP will guarantee that the oom
3169 * reaper will not run on this mm again after mmap_lock is
3170 * dropped.
3171 *
3172 * Nothing can be holding mm->mmap_lock here and the above call
3173 * to mmu_notifier_release(mm) ensures mmu notifier callbacks in
3174 * __oom_reap_task_mm() will not block.
3175 *
3176 * This needs to be done before calling munlock_vma_pages_all(),
3177 * which clears VM_LOCKED, otherwise the oom reaper cannot
3178 * reliably test it.
3179 */
3180 (void)__oom_reap_task_mm(mm);
3181
3182 set_bit(MMF_OOM_SKIP, &mm->flags);
3183 mmap_write_lock(mm);
3184 mmap_write_unlock(mm);
3185 }
3186
3187 if (mm->locked_vm)
3188 unlock_range(mm->mmap, ULONG_MAX);
3189
3190 arch_exit_mmap(mm);
3191
3192 vma = mm->mmap;
3193 if (!vma) /* Can happen if dup_mmap() received an OOM */
3194 return;
3195
3196 lru_add_drain();
3197 flush_cache_mm(mm);
3198 tlb_gather_mmu_fullmm(&tlb, mm);
3199 /* update_hiwater_rss(mm) here? but nobody should be looking */
3200 /* Use -1 here to ensure all VMAs in the mm are unmapped */
3201 unmap_vmas(&tlb, vma, 0, -1);
3202 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
3203 tlb_finish_mmu(&tlb);
3204
3205 /*
3206 * Walk the list again, actually closing and freeing it,
3207 * with preemption enabled, without holding any MM locks.
3208 */
3209 while (vma) {
3210 if (vma->vm_flags & VM_ACCOUNT)
3211 nr_accounted += vma_pages(vma);
3212 vma = remove_vma(vma);
3213 cond_resched();
3214 }
3215 vm_unacct_memory(nr_accounted);
3216}
3217
3218/* Insert vm structure into process list sorted by address
3219 * and into the inode's i_mmap tree. If vm_file is non-NULL
3220 * then i_mmap_rwsem is taken here.
3221 */
3222int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
3223{
3224 struct vm_area_struct *prev;
3225 struct rb_node **rb_link, *rb_parent;
3226
3227 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
3228 &prev, &rb_link, &rb_parent))
3229 return -ENOMEM;
3230 if ((vma->vm_flags & VM_ACCOUNT) &&
3231 security_vm_enough_memory_mm(mm, vma_pages(vma)))
3232 return -ENOMEM;
3233
3234 /*
3235 * The vm_pgoff of a purely anonymous vma should be irrelevant
3236 * until its first write fault, when page's anon_vma and index
3237 * are set. But now set the vm_pgoff it will almost certainly
3238 * end up with (unless mremap moves it elsewhere before that
3239 * first wfault), so /proc/pid/maps tells a consistent story.
3240 *
3241 * By setting it to reflect the virtual start address of the
3242 * vma, merges and splits can happen in a seamless way, just
3243 * using the existing file pgoff checks and manipulations.
3244 * Similarly in do_mmap and in do_brk_flags.
3245 */
3246 if (vma_is_anonymous(vma)) {
3247 BUG_ON(vma->anon_vma);
3248 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
3249 }
3250
3251 vma_link(mm, vma, prev, rb_link, rb_parent);
3252 return 0;
3253}
3254
3255/*
3256 * Copy the vma structure to a new location in the same mm,
3257 * prior to moving page table entries, to effect an mremap move.
3258 */
3259struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
3260 unsigned long addr, unsigned long len, pgoff_t pgoff,
3261 bool *need_rmap_locks)
3262{
3263 struct vm_area_struct *vma = *vmap;
3264 unsigned long vma_start = vma->vm_start;
3265 struct mm_struct *mm = vma->vm_mm;
3266 struct vm_area_struct *new_vma, *prev;
3267 struct rb_node **rb_link, *rb_parent;
3268 bool faulted_in_anon_vma = true;
3269
3270 /*
3271 * If anonymous vma has not yet been faulted, update new pgoff
3272 * to match new location, to increase its chance of merging.
3273 */
3274 if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
3275 pgoff = addr >> PAGE_SHIFT;
3276 faulted_in_anon_vma = false;
3277 }
3278
3279 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
3280 return NULL; /* should never get here */
3281 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
3282 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
3283 vma->vm_userfaultfd_ctx);
3284 if (new_vma) {
3285 /*
3286 * Source vma may have been merged into new_vma
3287 */
3288 if (unlikely(vma_start >= new_vma->vm_start &&
3289 vma_start < new_vma->vm_end)) {
3290 /*
3291 * The only way we can get a vma_merge with
3292 * self during an mremap is if the vma hasn't
3293 * been faulted in yet and we were allowed to
3294 * reset the dst vma->vm_pgoff to the
3295 * destination address of the mremap to allow
3296 * the merge to happen. mremap must change the
3297 * vm_pgoff linearity between src and dst vmas
3298 * (in turn preventing a vma_merge) to be
3299 * safe. It is only safe to keep the vm_pgoff
3300 * linear if there are no pages mapped yet.
3301 */
3302 VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
3303 *vmap = vma = new_vma;
3304 }
3305 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
3306 } else {
3307 new_vma = vm_area_dup(vma);
3308 if (!new_vma)
3309 goto out;
3310 new_vma->vm_start = addr;
3311 new_vma->vm_end = addr + len;
3312 new_vma->vm_pgoff = pgoff;
3313 if (vma_dup_policy(vma, new_vma))
3314 goto out_free_vma;
3315 if (anon_vma_clone(new_vma, vma))
3316 goto out_free_mempol;
3317 if (new_vma->vm_file)
3318 get_file(new_vma->vm_file);
3319 if (new_vma->vm_ops && new_vma->vm_ops->open)
3320 new_vma->vm_ops->open(new_vma);
3321 vma_link(mm, new_vma, prev, rb_link, rb_parent);
3322 *need_rmap_locks = false;
3323 }
3324 return new_vma;
3325
3326out_free_mempol:
3327 mpol_put(vma_policy(new_vma));
3328out_free_vma:
3329 vm_area_free(new_vma);
3330out:
3331 return NULL;
3332}
3333
3334/*
3335 * Return true if the calling process may expand its vm space by the passed
3336 * number of pages
3337 */
3338bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
3339{
3340 if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
3341 return false;
3342
3343 if (is_data_mapping(flags) &&
3344 mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
3345 /* Workaround for Valgrind */
3346 if (rlimit(RLIMIT_DATA) == 0 &&
3347 mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
3348 return true;
3349
3350 pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n",
3351 current->comm, current->pid,
3352 (mm->data_vm + npages) << PAGE_SHIFT,
3353 rlimit(RLIMIT_DATA),
3354 ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data");
3355
3356 if (!ignore_rlimit_data)
3357 return false;
3358 }
3359
3360 return true;
3361}
3362
3363void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
3364{
3365 mm->total_vm += npages;
3366
3367 if (is_exec_mapping(flags))
3368 mm->exec_vm += npages;
3369 else if (is_stack_mapping(flags))
3370 mm->stack_vm += npages;
3371 else if (is_data_mapping(flags))
3372 mm->data_vm += npages;
3373}
3374
3375static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
3376
3377/*
3378 * Having a close hook prevents vma merging regardless of flags.
3379 */
3380static void special_mapping_close(struct vm_area_struct *vma)
3381{
3382}
3383
3384static const char *special_mapping_name(struct vm_area_struct *vma)
3385{
3386 return ((struct vm_special_mapping *)vma->vm_private_data)->name;
3387}
3388
3389static int special_mapping_mremap(struct vm_area_struct *new_vma)
3390{
3391 struct vm_special_mapping *sm = new_vma->vm_private_data;
3392
3393 if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
3394 return -EFAULT;
3395
3396 if (sm->mremap)
3397 return sm->mremap(sm, new_vma);
3398
3399 return 0;
3400}
3401
3402static int special_mapping_split(struct vm_area_struct *vma, unsigned long addr)
3403{
3404 /*
3405 * Forbid splitting special mappings - kernel has expectations over
3406 * the number of pages in mapping. Together with VM_DONTEXPAND
3407 * the size of vma should stay the same over the special mapping's
3408 * lifetime.
3409 */
3410 return -EINVAL;
3411}
3412
3413static const struct vm_operations_struct special_mapping_vmops = {
3414 .close = special_mapping_close,
3415 .fault = special_mapping_fault,
3416 .mremap = special_mapping_mremap,
3417 .name = special_mapping_name,
3418 /* vDSO code relies that VVAR can't be accessed remotely */
3419 .access = NULL,
3420 .may_split = special_mapping_split,
3421};
3422
3423static const struct vm_operations_struct legacy_special_mapping_vmops = {
3424 .close = special_mapping_close,
3425 .fault = special_mapping_fault,
3426};
3427
3428static vm_fault_t special_mapping_fault(struct vm_fault *vmf)
3429{
3430 struct vm_area_struct *vma = vmf->vma;
3431 pgoff_t pgoff;
3432 struct page **pages;
3433
3434 if (vma->vm_ops == &legacy_special_mapping_vmops) {
3435 pages = vma->vm_private_data;
3436 } else {
3437 struct vm_special_mapping *sm = vma->vm_private_data;
3438
3439 if (sm->fault)
3440 return sm->fault(sm, vmf->vma, vmf);
3441
3442 pages = sm->pages;
3443 }
3444
3445 for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
3446 pgoff--;
3447
3448 if (*pages) {
3449 struct page *page = *pages;
3450 get_page(page);
3451 vmf->page = page;
3452 return 0;
3453 }
3454
3455 return VM_FAULT_SIGBUS;
3456}
3457
3458static struct vm_area_struct *__install_special_mapping(
3459 struct mm_struct *mm,
3460 unsigned long addr, unsigned long len,
3461 unsigned long vm_flags, void *priv,
3462 const struct vm_operations_struct *ops)
3463{
3464 int ret;
3465 struct vm_area_struct *vma;
3466
3467 vma = vm_area_alloc(mm);
3468 if (unlikely(vma == NULL))
3469 return ERR_PTR(-ENOMEM);
3470
3471 vma->vm_start = addr;
3472 vma->vm_end = addr + len;
3473
3474 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
3475 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
3476
3477 vma->vm_ops = ops;
3478 vma->vm_private_data = priv;
3479
3480 ret = insert_vm_struct(mm, vma);
3481 if (ret)
3482 goto out;
3483
3484 vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
3485
3486 perf_event_mmap(vma);
3487
3488 return vma;
3489
3490out:
3491 vm_area_free(vma);
3492 return ERR_PTR(ret);
3493}
3494
3495bool vma_is_special_mapping(const struct vm_area_struct *vma,
3496 const struct vm_special_mapping *sm)
3497{
3498 return vma->vm_private_data == sm &&
3499 (vma->vm_ops == &special_mapping_vmops ||
3500 vma->vm_ops == &legacy_special_mapping_vmops);
3501}
3502
3503/*
3504 * Called with mm->mmap_lock held for writing.
3505 * Insert a new vma covering the given region, with the given flags.
3506 * Its pages are supplied by the given array of struct page *.
3507 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
3508 * The region past the last page supplied will always produce SIGBUS.
3509 * The array pointer and the pages it points to are assumed to stay alive
3510 * for as long as this mapping might exist.
3511 */
3512struct vm_area_struct *_install_special_mapping(
3513 struct mm_struct *mm,
3514 unsigned long addr, unsigned long len,
3515 unsigned long vm_flags, const struct vm_special_mapping *spec)
3516{
3517 return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
3518 &special_mapping_vmops);
3519}
3520
3521int install_special_mapping(struct mm_struct *mm,
3522 unsigned long addr, unsigned long len,
3523 unsigned long vm_flags, struct page **pages)
3524{
3525 struct vm_area_struct *vma = __install_special_mapping(
3526 mm, addr, len, vm_flags, (void *)pages,
3527 &legacy_special_mapping_vmops);
3528
3529 return PTR_ERR_OR_ZERO(vma);
3530}
3531
3532static DEFINE_MUTEX(mm_all_locks_mutex);
3533
3534static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
3535{
3536 if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
3537 /*
3538 * The LSB of head.next can't change from under us
3539 * because we hold the mm_all_locks_mutex.
3540 */
3541 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_lock);
3542 /*
3543 * We can safely modify head.next after taking the
3544 * anon_vma->root->rwsem. If some other vma in this mm shares
3545 * the same anon_vma we won't take it again.
3546 *
3547 * No need of atomic instructions here, head.next
3548 * can't change from under us thanks to the
3549 * anon_vma->root->rwsem.
3550 */
3551 if (__test_and_set_bit(0, (unsigned long *)
3552 &anon_vma->root->rb_root.rb_root.rb_node))
3553 BUG();
3554 }
3555}
3556
3557static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
3558{
3559 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3560 /*
3561 * AS_MM_ALL_LOCKS can't change from under us because
3562 * we hold the mm_all_locks_mutex.
3563 *
3564 * Operations on ->flags have to be atomic because
3565 * even if AS_MM_ALL_LOCKS is stable thanks to the
3566 * mm_all_locks_mutex, there may be other cpus
3567 * changing other bitflags in parallel to us.
3568 */
3569 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
3570 BUG();
3571 down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_lock);
3572 }
3573}
3574
3575/*
3576 * This operation locks against the VM for all pte/vma/mm related
3577 * operations that could ever happen on a certain mm. This includes
3578 * vmtruncate, try_to_unmap, and all page faults.
3579 *
3580 * The caller must take the mmap_lock in write mode before calling
3581 * mm_take_all_locks(). The caller isn't allowed to release the
3582 * mmap_lock until mm_drop_all_locks() returns.
3583 *
3584 * mmap_lock in write mode is required in order to block all operations
3585 * that could modify pagetables and free pages without need of
3586 * altering the vma layout. It's also needed in write mode to avoid new
3587 * anon_vmas to be associated with existing vmas.
3588 *
3589 * A single task can't take more than one mm_take_all_locks() in a row
3590 * or it would deadlock.
3591 *
3592 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3593 * mapping->flags avoid to take the same lock twice, if more than one
3594 * vma in this mm is backed by the same anon_vma or address_space.
3595 *
3596 * We take locks in following order, accordingly to comment at beginning
3597 * of mm/rmap.c:
3598 * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
3599 * hugetlb mapping);
3600 * - all i_mmap_rwsem locks;
3601 * - all anon_vma->rwseml
3602 *
3603 * We can take all locks within these types randomly because the VM code
3604 * doesn't nest them and we protected from parallel mm_take_all_locks() by
3605 * mm_all_locks_mutex.
3606 *
3607 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3608 * that may have to take thousand of locks.
3609 *
3610 * mm_take_all_locks() can fail if it's interrupted by signals.
3611 */
3612int mm_take_all_locks(struct mm_struct *mm)
3613{
3614 struct vm_area_struct *vma;
3615 struct anon_vma_chain *avc;
3616
3617 BUG_ON(mmap_read_trylock(mm));
3618
3619 mutex_lock(&mm_all_locks_mutex);
3620
3621 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3622 if (signal_pending(current))
3623 goto out_unlock;
3624 if (vma->vm_file && vma->vm_file->f_mapping &&
3625 is_vm_hugetlb_page(vma))
3626 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3627 }
3628
3629 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3630 if (signal_pending(current))
3631 goto out_unlock;
3632 if (vma->vm_file && vma->vm_file->f_mapping &&
3633 !is_vm_hugetlb_page(vma))
3634 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3635 }
3636
3637 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3638 if (signal_pending(current))
3639 goto out_unlock;
3640 if (vma->anon_vma)
3641 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3642 vm_lock_anon_vma(mm, avc->anon_vma);
3643 }
3644
3645 return 0;
3646
3647out_unlock:
3648 mm_drop_all_locks(mm);
3649 return -EINTR;
3650}
3651
3652static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3653{
3654 if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
3655 /*
3656 * The LSB of head.next can't change to 0 from under
3657 * us because we hold the mm_all_locks_mutex.
3658 *
3659 * We must however clear the bitflag before unlocking
3660 * the vma so the users using the anon_vma->rb_root will
3661 * never see our bitflag.
3662 *
3663 * No need of atomic instructions here, head.next
3664 * can't change from under us until we release the
3665 * anon_vma->root->rwsem.
3666 */
3667 if (!__test_and_clear_bit(0, (unsigned long *)
3668 &anon_vma->root->rb_root.rb_root.rb_node))
3669 BUG();
3670 anon_vma_unlock_write(anon_vma);
3671 }
3672}
3673
3674static void vm_unlock_mapping(struct address_space *mapping)
3675{
3676 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3677 /*
3678 * AS_MM_ALL_LOCKS can't change to 0 from under us
3679 * because we hold the mm_all_locks_mutex.
3680 */
3681 i_mmap_unlock_write(mapping);
3682 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
3683 &mapping->flags))
3684 BUG();
3685 }
3686}
3687
3688/*
3689 * The mmap_lock cannot be released by the caller until
3690 * mm_drop_all_locks() returns.
3691 */
3692void mm_drop_all_locks(struct mm_struct *mm)
3693{
3694 struct vm_area_struct *vma;
3695 struct anon_vma_chain *avc;
3696
3697 BUG_ON(mmap_read_trylock(mm));
3698 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3699
3700 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3701 if (vma->anon_vma)
3702 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3703 vm_unlock_anon_vma(avc->anon_vma);
3704 if (vma->vm_file && vma->vm_file->f_mapping)
3705 vm_unlock_mapping(vma->vm_file->f_mapping);
3706 }
3707
3708 mutex_unlock(&mm_all_locks_mutex);
3709}
3710
3711/*
3712 * initialise the percpu counter for VM
3713 */
3714void __init mmap_init(void)
3715{
3716 int ret;
3717
3718 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
3719 VM_BUG_ON(ret);
3720}
3721
3722/*
3723 * Initialise sysctl_user_reserve_kbytes.
3724 *
3725 * This is intended to prevent a user from starting a single memory hogging
3726 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3727 * mode.
3728 *
3729 * The default value is min(3% of free memory, 128MB)
3730 * 128MB is enough to recover with sshd/login, bash, and top/kill.
3731 */
3732static int init_user_reserve(void)
3733{
3734 unsigned long free_kbytes;
3735
3736 free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3737
3738 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
3739 return 0;
3740}
3741subsys_initcall(init_user_reserve);
3742
3743/*
3744 * Initialise sysctl_admin_reserve_kbytes.
3745 *
3746 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3747 * to log in and kill a memory hogging process.
3748 *
3749 * Systems with more than 256MB will reserve 8MB, enough to recover
3750 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3751 * only reserve 3% of free pages by default.
3752 */
3753static int init_admin_reserve(void)
3754{
3755 unsigned long free_kbytes;
3756
3757 free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3758
3759 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
3760 return 0;
3761}
3762subsys_initcall(init_admin_reserve);
3763
3764/*
3765 * Reinititalise user and admin reserves if memory is added or removed.
3766 *
3767 * The default user reserve max is 128MB, and the default max for the
3768 * admin reserve is 8MB. These are usually, but not always, enough to
3769 * enable recovery from a memory hogging process using login/sshd, a shell,
3770 * and tools like top. It may make sense to increase or even disable the
3771 * reserve depending on the existence of swap or variations in the recovery
3772 * tools. So, the admin may have changed them.
3773 *
3774 * If memory is added and the reserves have been eliminated or increased above
3775 * the default max, then we'll trust the admin.
3776 *
3777 * If memory is removed and there isn't enough free memory, then we
3778 * need to reset the reserves.
3779 *
3780 * Otherwise keep the reserve set by the admin.
3781 */
3782static int reserve_mem_notifier(struct notifier_block *nb,
3783 unsigned long action, void *data)
3784{
3785 unsigned long tmp, free_kbytes;
3786
3787 switch (action) {
3788 case MEM_ONLINE:
3789 /* Default max is 128MB. Leave alone if modified by operator. */
3790 tmp = sysctl_user_reserve_kbytes;
3791 if (0 < tmp && tmp < (1UL << 17))
3792 init_user_reserve();
3793
3794 /* Default max is 8MB. Leave alone if modified by operator. */
3795 tmp = sysctl_admin_reserve_kbytes;
3796 if (0 < tmp && tmp < (1UL << 13))
3797 init_admin_reserve();
3798
3799 break;
3800 case MEM_OFFLINE:
3801 free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3802
3803 if (sysctl_user_reserve_kbytes > free_kbytes) {
3804 init_user_reserve();
3805 pr_info("vm.user_reserve_kbytes reset to %lu\n",
3806 sysctl_user_reserve_kbytes);
3807 }
3808
3809 if (sysctl_admin_reserve_kbytes > free_kbytes) {
3810 init_admin_reserve();
3811 pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3812 sysctl_admin_reserve_kbytes);
3813 }
3814 break;
3815 default:
3816 break;
3817 }
3818 return NOTIFY_OK;
3819}
3820
3821static struct notifier_block reserve_mem_nb = {
3822 .notifier_call = reserve_mem_notifier,
3823};
3824
3825static int __meminit init_reserve_notifier(void)
3826{
3827 if (register_hotmemory_notifier(&reserve_mem_nb))
3828 pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3829
3830 return 0;
3831}
3832subsys_initcall(init_reserve_notifier);