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