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11#include <linux/mm.h>
12#include <linux/hugetlb.h>
13#include <linux/shm.h>
14#include <linux/ksm.h>
15#include <linux/mman.h>
16#include <linux/swap.h>
17#include <linux/capability.h>
18#include <linux/fs.h>
19#include <linux/swapops.h>
20#include <linux/highmem.h>
21#include <linux/security.h>
22#include <linux/syscalls.h>
23#include <linux/mmu_notifier.h>
24#include <linux/uaccess.h>
25#include <linux/userfaultfd_k.h>
26
27#include <asm/cacheflush.h>
28#include <asm/tlb.h>
29#include <asm/pgalloc.h>
30
31#include "internal.h"
32
33static pud_t *get_old_pud(struct mm_struct *mm, unsigned long addr)
34{
35 pgd_t *pgd;
36 p4d_t *p4d;
37 pud_t *pud;
38
39 pgd = pgd_offset(mm, addr);
40 if (pgd_none_or_clear_bad(pgd))
41 return NULL;
42
43 p4d = p4d_offset(pgd, addr);
44 if (p4d_none_or_clear_bad(p4d))
45 return NULL;
46
47 pud = pud_offset(p4d, addr);
48 if (pud_none_or_clear_bad(pud))
49 return NULL;
50
51 return pud;
52}
53
54static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
55{
56 pud_t *pud;
57 pmd_t *pmd;
58
59 pud = get_old_pud(mm, addr);
60 if (!pud)
61 return NULL;
62
63 pmd = pmd_offset(pud, addr);
64 if (pmd_none(*pmd))
65 return NULL;
66
67 return pmd;
68}
69
70static pud_t *alloc_new_pud(struct mm_struct *mm, struct vm_area_struct *vma,
71 unsigned long addr)
72{
73 pgd_t *pgd;
74 p4d_t *p4d;
75
76 pgd = pgd_offset(mm, addr);
77 p4d = p4d_alloc(mm, pgd, addr);
78 if (!p4d)
79 return NULL;
80
81 return pud_alloc(mm, p4d, addr);
82}
83
84static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
85 unsigned long addr)
86{
87 pud_t *pud;
88 pmd_t *pmd;
89
90 pud = alloc_new_pud(mm, vma, addr);
91 if (!pud)
92 return NULL;
93
94 pmd = pmd_alloc(mm, pud, addr);
95 if (!pmd)
96 return NULL;
97
98 VM_BUG_ON(pmd_trans_huge(*pmd));
99
100 return pmd;
101}
102
103static void take_rmap_locks(struct vm_area_struct *vma)
104{
105 if (vma->vm_file)
106 i_mmap_lock_write(vma->vm_file->f_mapping);
107 if (vma->anon_vma)
108 anon_vma_lock_write(vma->anon_vma);
109}
110
111static void drop_rmap_locks(struct vm_area_struct *vma)
112{
113 if (vma->anon_vma)
114 anon_vma_unlock_write(vma->anon_vma);
115 if (vma->vm_file)
116 i_mmap_unlock_write(vma->vm_file->f_mapping);
117}
118
119static pte_t move_soft_dirty_pte(pte_t pte)
120{
121
122
123
124
125#ifdef CONFIG_MEM_SOFT_DIRTY
126 if (pte_present(pte))
127 pte = pte_mksoft_dirty(pte);
128 else if (is_swap_pte(pte))
129 pte = pte_swp_mksoft_dirty(pte);
130#endif
131 return pte;
132}
133
134static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
135 unsigned long old_addr, unsigned long old_end,
136 struct vm_area_struct *new_vma, pmd_t *new_pmd,
137 unsigned long new_addr, bool need_rmap_locks)
138{
139 struct mm_struct *mm = vma->vm_mm;
140 pte_t *old_pte, *new_pte, pte;
141 spinlock_t *old_ptl, *new_ptl;
142 bool force_flush = false;
143 unsigned long len = old_end - old_addr;
144
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161
162
163 if (need_rmap_locks)
164 take_rmap_locks(vma);
165
166
167
168
169
170 old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
171 new_pte = pte_offset_map(new_pmd, new_addr);
172 new_ptl = pte_lockptr(mm, new_pmd);
173 if (new_ptl != old_ptl)
174 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
175 flush_tlb_batched_pending(vma->vm_mm);
176 arch_enter_lazy_mmu_mode();
177
178 for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
179 new_pte++, new_addr += PAGE_SIZE) {
180 if (pte_none(*old_pte))
181 continue;
182
183 pte = ptep_get_and_clear(mm, old_addr, old_pte);
184
185
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188
189
190
191
192
193
194
195 if (pte_present(pte))
196 force_flush = true;
197 pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
198 pte = move_soft_dirty_pte(pte);
199 set_pte_at(mm, new_addr, new_pte, pte);
200 }
201
202 arch_leave_lazy_mmu_mode();
203 if (force_flush)
204 flush_tlb_range(vma, old_end - len, old_end);
205 if (new_ptl != old_ptl)
206 spin_unlock(new_ptl);
207 pte_unmap(new_pte - 1);
208 pte_unmap_unlock(old_pte - 1, old_ptl);
209 if (need_rmap_locks)
210 drop_rmap_locks(vma);
211}
212
213#ifndef arch_supports_page_table_move
214#define arch_supports_page_table_move arch_supports_page_table_move
215static inline bool arch_supports_page_table_move(void)
216{
217 return IS_ENABLED(CONFIG_HAVE_MOVE_PMD) ||
218 IS_ENABLED(CONFIG_HAVE_MOVE_PUD);
219}
220#endif
221
222#ifdef CONFIG_HAVE_MOVE_PMD
223static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
224 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd)
225{
226 spinlock_t *old_ptl, *new_ptl;
227 struct mm_struct *mm = vma->vm_mm;
228 pmd_t pmd;
229
230 if (!arch_supports_page_table_move())
231 return false;
232
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253
254
255 if (WARN_ON_ONCE(!pmd_none(*new_pmd)))
256 return false;
257
258
259
260
261
262 old_ptl = pmd_lock(vma->vm_mm, old_pmd);
263 new_ptl = pmd_lockptr(mm, new_pmd);
264 if (new_ptl != old_ptl)
265 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
266
267
268 pmd = *old_pmd;
269 pmd_clear(old_pmd);
270
271 VM_BUG_ON(!pmd_none(*new_pmd));
272
273 pmd_populate(mm, new_pmd, pmd_pgtable(pmd));
274 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
275 if (new_ptl != old_ptl)
276 spin_unlock(new_ptl);
277 spin_unlock(old_ptl);
278
279 return true;
280}
281#else
282static inline bool move_normal_pmd(struct vm_area_struct *vma,
283 unsigned long old_addr, unsigned long new_addr, pmd_t *old_pmd,
284 pmd_t *new_pmd)
285{
286 return false;
287}
288#endif
289
290#if CONFIG_PGTABLE_LEVELS > 2 && defined(CONFIG_HAVE_MOVE_PUD)
291static bool move_normal_pud(struct vm_area_struct *vma, unsigned long old_addr,
292 unsigned long new_addr, pud_t *old_pud, pud_t *new_pud)
293{
294 spinlock_t *old_ptl, *new_ptl;
295 struct mm_struct *mm = vma->vm_mm;
296 pud_t pud;
297
298 if (!arch_supports_page_table_move())
299 return false;
300
301
302
303
304 if (WARN_ON_ONCE(!pud_none(*new_pud)))
305 return false;
306
307
308
309
310
311 old_ptl = pud_lock(vma->vm_mm, old_pud);
312 new_ptl = pud_lockptr(mm, new_pud);
313 if (new_ptl != old_ptl)
314 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
315
316
317 pud = *old_pud;
318 pud_clear(old_pud);
319
320 VM_BUG_ON(!pud_none(*new_pud));
321
322 pud_populate(mm, new_pud, pud_pgtable(pud));
323 flush_tlb_range(vma, old_addr, old_addr + PUD_SIZE);
324 if (new_ptl != old_ptl)
325 spin_unlock(new_ptl);
326 spin_unlock(old_ptl);
327
328 return true;
329}
330#else
331static inline bool move_normal_pud(struct vm_area_struct *vma,
332 unsigned long old_addr, unsigned long new_addr, pud_t *old_pud,
333 pud_t *new_pud)
334{
335 return false;
336}
337#endif
338
339#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
340static bool move_huge_pud(struct vm_area_struct *vma, unsigned long old_addr,
341 unsigned long new_addr, pud_t *old_pud, pud_t *new_pud)
342{
343 spinlock_t *old_ptl, *new_ptl;
344 struct mm_struct *mm = vma->vm_mm;
345 pud_t pud;
346
347
348
349
350
351 if (WARN_ON_ONCE(!pud_none(*new_pud)))
352 return false;
353
354
355
356
357
358 old_ptl = pud_lock(vma->vm_mm, old_pud);
359 new_ptl = pud_lockptr(mm, new_pud);
360 if (new_ptl != old_ptl)
361 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
362
363
364 pud = *old_pud;
365 pud_clear(old_pud);
366
367 VM_BUG_ON(!pud_none(*new_pud));
368
369
370
371 set_pud_at(mm, new_addr, new_pud, pud);
372 flush_pud_tlb_range(vma, old_addr, old_addr + HPAGE_PUD_SIZE);
373 if (new_ptl != old_ptl)
374 spin_unlock(new_ptl);
375 spin_unlock(old_ptl);
376
377 return true;
378}
379#else
380static bool move_huge_pud(struct vm_area_struct *vma, unsigned long old_addr,
381 unsigned long new_addr, pud_t *old_pud, pud_t *new_pud)
382{
383 WARN_ON_ONCE(1);
384 return false;
385
386}
387#endif
388
389enum pgt_entry {
390 NORMAL_PMD,
391 HPAGE_PMD,
392 NORMAL_PUD,
393 HPAGE_PUD,
394};
395
396
397
398
399
400
401static __always_inline unsigned long get_extent(enum pgt_entry entry,
402 unsigned long old_addr, unsigned long old_end,
403 unsigned long new_addr)
404{
405 unsigned long next, extent, mask, size;
406
407 switch (entry) {
408 case HPAGE_PMD:
409 case NORMAL_PMD:
410 mask = PMD_MASK;
411 size = PMD_SIZE;
412 break;
413 case HPAGE_PUD:
414 case NORMAL_PUD:
415 mask = PUD_MASK;
416 size = PUD_SIZE;
417 break;
418 default:
419 BUILD_BUG();
420 break;
421 }
422
423 next = (old_addr + size) & mask;
424
425 extent = next - old_addr;
426 if (extent > old_end - old_addr)
427 extent = old_end - old_addr;
428 next = (new_addr + size) & mask;
429 if (extent > next - new_addr)
430 extent = next - new_addr;
431 return extent;
432}
433
434
435
436
437
438static bool move_pgt_entry(enum pgt_entry entry, struct vm_area_struct *vma,
439 unsigned long old_addr, unsigned long new_addr,
440 void *old_entry, void *new_entry, bool need_rmap_locks)
441{
442 bool moved = false;
443
444
445 if (need_rmap_locks)
446 take_rmap_locks(vma);
447
448 switch (entry) {
449 case NORMAL_PMD:
450 moved = move_normal_pmd(vma, old_addr, new_addr, old_entry,
451 new_entry);
452 break;
453 case NORMAL_PUD:
454 moved = move_normal_pud(vma, old_addr, new_addr, old_entry,
455 new_entry);
456 break;
457 case HPAGE_PMD:
458 moved = IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
459 move_huge_pmd(vma, old_addr, new_addr, old_entry,
460 new_entry);
461 break;
462 case HPAGE_PUD:
463 moved = IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
464 move_huge_pud(vma, old_addr, new_addr, old_entry,
465 new_entry);
466 break;
467
468 default:
469 WARN_ON_ONCE(1);
470 break;
471 }
472
473 if (need_rmap_locks)
474 drop_rmap_locks(vma);
475
476 return moved;
477}
478
479unsigned long move_page_tables(struct vm_area_struct *vma,
480 unsigned long old_addr, struct vm_area_struct *new_vma,
481 unsigned long new_addr, unsigned long len,
482 bool need_rmap_locks)
483{
484 unsigned long extent, old_end;
485 struct mmu_notifier_range range;
486 pmd_t *old_pmd, *new_pmd;
487 pud_t *old_pud, *new_pud;
488
489 old_end = old_addr + len;
490 flush_cache_range(vma, old_addr, old_end);
491
492 if (is_vm_hugetlb_page(vma))
493 return move_hugetlb_page_tables(vma, new_vma, old_addr,
494 new_addr, len);
495
496 mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, vma->vm_mm,
497 old_addr, old_end);
498 mmu_notifier_invalidate_range_start(&range);
499
500 for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
501 cond_resched();
502
503
504
505
506 extent = get_extent(NORMAL_PUD, old_addr, old_end, new_addr);
507
508 old_pud = get_old_pud(vma->vm_mm, old_addr);
509 if (!old_pud)
510 continue;
511 new_pud = alloc_new_pud(vma->vm_mm, vma, new_addr);
512 if (!new_pud)
513 break;
514 if (pud_trans_huge(*old_pud) || pud_devmap(*old_pud)) {
515 if (extent == HPAGE_PUD_SIZE) {
516 move_pgt_entry(HPAGE_PUD, vma, old_addr, new_addr,
517 old_pud, new_pud, need_rmap_locks);
518
519 continue;
520 }
521 } else if (IS_ENABLED(CONFIG_HAVE_MOVE_PUD) && extent == PUD_SIZE) {
522
523 if (move_pgt_entry(NORMAL_PUD, vma, old_addr, new_addr,
524 old_pud, new_pud, true))
525 continue;
526 }
527
528 extent = get_extent(NORMAL_PMD, old_addr, old_end, new_addr);
529 old_pmd = get_old_pmd(vma->vm_mm, old_addr);
530 if (!old_pmd)
531 continue;
532 new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
533 if (!new_pmd)
534 break;
535 if (is_swap_pmd(*old_pmd) || pmd_trans_huge(*old_pmd) ||
536 pmd_devmap(*old_pmd)) {
537 if (extent == HPAGE_PMD_SIZE &&
538 move_pgt_entry(HPAGE_PMD, vma, old_addr, new_addr,
539 old_pmd, new_pmd, need_rmap_locks))
540 continue;
541 split_huge_pmd(vma, old_pmd, old_addr);
542 if (pmd_trans_unstable(old_pmd))
543 continue;
544 } else if (IS_ENABLED(CONFIG_HAVE_MOVE_PMD) &&
545 extent == PMD_SIZE) {
546
547
548
549
550 if (move_pgt_entry(NORMAL_PMD, vma, old_addr, new_addr,
551 old_pmd, new_pmd, true))
552 continue;
553 }
554
555 if (pte_alloc(new_vma->vm_mm, new_pmd))
556 break;
557 move_ptes(vma, old_pmd, old_addr, old_addr + extent, new_vma,
558 new_pmd, new_addr, need_rmap_locks);
559 }
560
561 mmu_notifier_invalidate_range_end(&range);
562
563 return len + old_addr - old_end;
564}
565
566static unsigned long move_vma(struct vm_area_struct *vma,
567 unsigned long old_addr, unsigned long old_len,
568 unsigned long new_len, unsigned long new_addr,
569 bool *locked, unsigned long flags,
570 struct vm_userfaultfd_ctx *uf, struct list_head *uf_unmap)
571{
572 long to_account = new_len - old_len;
573 struct mm_struct *mm = vma->vm_mm;
574 struct vm_area_struct *new_vma;
575 unsigned long vm_flags = vma->vm_flags;
576 unsigned long new_pgoff;
577 unsigned long moved_len;
578 unsigned long excess = 0;
579 unsigned long hiwater_vm;
580 int split = 0;
581 int err = 0;
582 bool need_rmap_locks;
583
584
585
586
587
588 if (mm->map_count >= sysctl_max_map_count - 3)
589 return -ENOMEM;
590
591 if (unlikely(flags & MREMAP_DONTUNMAP))
592 to_account = new_len;
593
594 if (vma->vm_ops && vma->vm_ops->may_split) {
595 if (vma->vm_start != old_addr)
596 err = vma->vm_ops->may_split(vma, old_addr);
597 if (!err && vma->vm_end != old_addr + old_len)
598 err = vma->vm_ops->may_split(vma, old_addr + old_len);
599 if (err)
600 return err;
601 }
602
603
604
605
606
607
608
609
610 err = ksm_madvise(vma, old_addr, old_addr + old_len,
611 MADV_UNMERGEABLE, &vm_flags);
612 if (err)
613 return err;
614
615 if (vm_flags & VM_ACCOUNT) {
616 if (security_vm_enough_memory_mm(mm, to_account >> PAGE_SHIFT))
617 return -ENOMEM;
618 }
619
620 new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
621 new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff,
622 &need_rmap_locks);
623 if (!new_vma) {
624 if (vm_flags & VM_ACCOUNT)
625 vm_unacct_memory(to_account >> PAGE_SHIFT);
626 return -ENOMEM;
627 }
628
629 moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len,
630 need_rmap_locks);
631 if (moved_len < old_len) {
632 err = -ENOMEM;
633 } else if (vma->vm_ops && vma->vm_ops->mremap) {
634 err = vma->vm_ops->mremap(new_vma);
635 }
636
637 if (unlikely(err)) {
638
639
640
641
642
643 move_page_tables(new_vma, new_addr, vma, old_addr, moved_len,
644 true);
645 vma = new_vma;
646 old_len = new_len;
647 old_addr = new_addr;
648 new_addr = err;
649 } else {
650 mremap_userfaultfd_prep(new_vma, uf);
651 }
652
653 if (is_vm_hugetlb_page(vma)) {
654 clear_vma_resv_huge_pages(vma);
655 }
656
657
658 if (vm_flags & VM_ACCOUNT && !(flags & MREMAP_DONTUNMAP)) {
659 vma->vm_flags &= ~VM_ACCOUNT;
660 excess = vma->vm_end - vma->vm_start - old_len;
661 if (old_addr > vma->vm_start &&
662 old_addr + old_len < vma->vm_end)
663 split = 1;
664 }
665
666
667
668
669
670
671
672
673
674
675 hiwater_vm = mm->hiwater_vm;
676 vm_stat_account(mm, vma->vm_flags, new_len >> PAGE_SHIFT);
677
678
679 if (unlikely(vma->vm_flags & VM_PFNMAP))
680 untrack_pfn_moved(vma);
681
682 if (unlikely(!err && (flags & MREMAP_DONTUNMAP))) {
683
684 vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
685
686
687
688
689
690 if (new_vma != vma && vma->vm_start == old_addr &&
691 vma->vm_end == (old_addr + old_len))
692 unlink_anon_vmas(vma);
693
694
695 return new_addr;
696 }
697
698 if (do_munmap(mm, old_addr, old_len, uf_unmap) < 0) {
699
700 if (vm_flags & VM_ACCOUNT && !(flags & MREMAP_DONTUNMAP))
701 vm_acct_memory(old_len >> PAGE_SHIFT);
702 excess = 0;
703 }
704
705 if (vm_flags & VM_LOCKED) {
706 mm->locked_vm += new_len >> PAGE_SHIFT;
707 *locked = true;
708 }
709
710 mm->hiwater_vm = hiwater_vm;
711
712
713 if (excess) {
714 vma->vm_flags |= VM_ACCOUNT;
715 if (split)
716 vma->vm_next->vm_flags |= VM_ACCOUNT;
717 }
718
719 return new_addr;
720}
721
722static struct vm_area_struct *vma_to_resize(unsigned long addr,
723 unsigned long old_len, unsigned long new_len, unsigned long flags)
724{
725 struct mm_struct *mm = current->mm;
726 struct vm_area_struct *vma;
727 unsigned long pgoff;
728
729 vma = vma_lookup(mm, addr);
730 if (!vma)
731 return ERR_PTR(-EFAULT);
732
733
734
735
736
737
738
739
740
741 if (!old_len && !(vma->vm_flags & (VM_SHARED | VM_MAYSHARE))) {
742 pr_warn_once("%s (%d): attempted to duplicate a private mapping with mremap. This is not supported.\n", current->comm, current->pid);
743 return ERR_PTR(-EINVAL);
744 }
745
746 if ((flags & MREMAP_DONTUNMAP) &&
747 (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)))
748 return ERR_PTR(-EINVAL);
749
750
751 if (old_len > vma->vm_end - addr)
752 return ERR_PTR(-EFAULT);
753
754 if (new_len == old_len)
755 return vma;
756
757
758 pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
759 pgoff += vma->vm_pgoff;
760 if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
761 return ERR_PTR(-EINVAL);
762
763 if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
764 return ERR_PTR(-EFAULT);
765
766 if (vma->vm_flags & VM_LOCKED) {
767 unsigned long locked, lock_limit;
768 locked = mm->locked_vm << PAGE_SHIFT;
769 lock_limit = rlimit(RLIMIT_MEMLOCK);
770 locked += new_len - old_len;
771 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
772 return ERR_PTR(-EAGAIN);
773 }
774
775 if (!may_expand_vm(mm, vma->vm_flags,
776 (new_len - old_len) >> PAGE_SHIFT))
777 return ERR_PTR(-ENOMEM);
778
779 return vma;
780}
781
782static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
783 unsigned long new_addr, unsigned long new_len, bool *locked,
784 unsigned long flags, struct vm_userfaultfd_ctx *uf,
785 struct list_head *uf_unmap_early,
786 struct list_head *uf_unmap)
787{
788 struct mm_struct *mm = current->mm;
789 struct vm_area_struct *vma;
790 unsigned long ret = -EINVAL;
791 unsigned long map_flags = 0;
792
793 if (offset_in_page(new_addr))
794 goto out;
795
796 if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
797 goto out;
798
799
800 if (addr + old_len > new_addr && new_addr + new_len > addr)
801 goto out;
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817 if ((mm->map_count + 2) >= sysctl_max_map_count - 3)
818 return -ENOMEM;
819
820 if (flags & MREMAP_FIXED) {
821 ret = do_munmap(mm, new_addr, new_len, uf_unmap_early);
822 if (ret)
823 goto out;
824 }
825
826 if (old_len >= new_len) {
827 ret = do_munmap(mm, addr+new_len, old_len - new_len, uf_unmap);
828 if (ret && old_len != new_len)
829 goto out;
830 old_len = new_len;
831 }
832
833 vma = vma_to_resize(addr, old_len, new_len, flags);
834 if (IS_ERR(vma)) {
835 ret = PTR_ERR(vma);
836 goto out;
837 }
838
839
840 if (flags & MREMAP_DONTUNMAP &&
841 !may_expand_vm(mm, vma->vm_flags, old_len >> PAGE_SHIFT)) {
842 ret = -ENOMEM;
843 goto out;
844 }
845
846 if (flags & MREMAP_FIXED)
847 map_flags |= MAP_FIXED;
848
849 if (vma->vm_flags & VM_MAYSHARE)
850 map_flags |= MAP_SHARED;
851
852 ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
853 ((addr - vma->vm_start) >> PAGE_SHIFT),
854 map_flags);
855 if (IS_ERR_VALUE(ret))
856 goto out;
857
858
859 if (!(flags & MREMAP_FIXED))
860 new_addr = ret;
861
862 ret = move_vma(vma, addr, old_len, new_len, new_addr, locked, flags, uf,
863 uf_unmap);
864
865out:
866 return ret;
867}
868
869static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
870{
871 unsigned long end = vma->vm_end + delta;
872 if (end < vma->vm_end)
873 return 0;
874 if (vma->vm_next && vma->vm_next->vm_start < end)
875 return 0;
876 if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
877 0, MAP_FIXED) & ~PAGE_MASK)
878 return 0;
879 return 1;
880}
881
882
883
884
885
886
887
888
889SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
890 unsigned long, new_len, unsigned long, flags,
891 unsigned long, new_addr)
892{
893 struct mm_struct *mm = current->mm;
894 struct vm_area_struct *vma;
895 unsigned long ret = -EINVAL;
896 bool locked = false;
897 bool downgraded = false;
898 struct vm_userfaultfd_ctx uf = NULL_VM_UFFD_CTX;
899 LIST_HEAD(uf_unmap_early);
900 LIST_HEAD(uf_unmap);
901
902
903
904
905
906
907
908
909
910
911
912 addr = untagged_addr(addr);
913
914 if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE | MREMAP_DONTUNMAP))
915 return ret;
916
917 if (flags & MREMAP_FIXED && !(flags & MREMAP_MAYMOVE))
918 return ret;
919
920
921
922
923
924 if (flags & MREMAP_DONTUNMAP &&
925 (!(flags & MREMAP_MAYMOVE) || old_len != new_len))
926 return ret;
927
928
929 if (offset_in_page(addr))
930 return ret;
931
932 old_len = PAGE_ALIGN(old_len);
933 new_len = PAGE_ALIGN(new_len);
934
935
936
937
938
939
940 if (!new_len)
941 return ret;
942
943 if (mmap_write_lock_killable(current->mm))
944 return -EINTR;
945 vma = find_vma(mm, addr);
946 if (!vma || vma->vm_start > addr) {
947 ret = EFAULT;
948 goto out;
949 }
950
951 if (is_vm_hugetlb_page(vma)) {
952 struct hstate *h __maybe_unused = hstate_vma(vma);
953
954 old_len = ALIGN(old_len, huge_page_size(h));
955 new_len = ALIGN(new_len, huge_page_size(h));
956
957
958 if (addr & ~huge_page_mask(h))
959 goto out;
960 if (new_addr & ~huge_page_mask(h))
961 goto out;
962
963
964
965
966
967 if (new_len > old_len)
968 goto out;
969 }
970
971 if (flags & (MREMAP_FIXED | MREMAP_DONTUNMAP)) {
972 ret = mremap_to(addr, old_len, new_addr, new_len,
973 &locked, flags, &uf, &uf_unmap_early,
974 &uf_unmap);
975 goto out;
976 }
977
978
979
980
981
982
983
984 if (old_len >= new_len) {
985 int retval;
986
987 retval = __do_munmap(mm, addr+new_len, old_len - new_len,
988 &uf_unmap, true);
989 if (retval < 0 && old_len != new_len) {
990 ret = retval;
991 goto out;
992
993 } else if (retval == 1)
994 downgraded = true;
995 ret = addr;
996 goto out;
997 }
998
999
1000
1001
1002 vma = vma_to_resize(addr, old_len, new_len, flags);
1003 if (IS_ERR(vma)) {
1004 ret = PTR_ERR(vma);
1005 goto out;
1006 }
1007
1008
1009
1010 if (old_len == vma->vm_end - addr) {
1011
1012 if (vma_expandable(vma, new_len - old_len)) {
1013 long pages = (new_len - old_len) >> PAGE_SHIFT;
1014
1015 if (vma->vm_flags & VM_ACCOUNT) {
1016 if (security_vm_enough_memory_mm(mm, pages)) {
1017 ret = -ENOMEM;
1018 goto out;
1019 }
1020 }
1021
1022 if (vma_adjust(vma, vma->vm_start, addr + new_len,
1023 vma->vm_pgoff, NULL)) {
1024 vm_unacct_memory(pages);
1025 ret = -ENOMEM;
1026 goto out;
1027 }
1028
1029 vm_stat_account(mm, vma->vm_flags, pages);
1030 if (vma->vm_flags & VM_LOCKED) {
1031 mm->locked_vm += pages;
1032 locked = true;
1033 new_addr = addr;
1034 }
1035 ret = addr;
1036 goto out;
1037 }
1038 }
1039
1040
1041
1042
1043
1044 ret = -ENOMEM;
1045 if (flags & MREMAP_MAYMOVE) {
1046 unsigned long map_flags = 0;
1047 if (vma->vm_flags & VM_MAYSHARE)
1048 map_flags |= MAP_SHARED;
1049
1050 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
1051 vma->vm_pgoff +
1052 ((addr - vma->vm_start) >> PAGE_SHIFT),
1053 map_flags);
1054 if (IS_ERR_VALUE(new_addr)) {
1055 ret = new_addr;
1056 goto out;
1057 }
1058
1059 ret = move_vma(vma, addr, old_len, new_len, new_addr,
1060 &locked, flags, &uf, &uf_unmap);
1061 }
1062out:
1063 if (offset_in_page(ret))
1064 locked = false;
1065 if (downgraded)
1066 mmap_read_unlock(current->mm);
1067 else
1068 mmap_write_unlock(current->mm);
1069 if (locked && new_len > old_len)
1070 mm_populate(new_addr + old_len, new_len - old_len);
1071 userfaultfd_unmap_complete(mm, &uf_unmap_early);
1072 mremap_userfaultfd_complete(&uf, addr, ret, old_len);
1073 userfaultfd_unmap_complete(mm, &uf_unmap);
1074 return ret;
1075}
1076