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1/*
2 * mm/mremap.c
3 *
4 * (C) Copyright 1996 Linus Torvalds
5 *
6 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
7 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
8 */
9
10#include <linux/mm.h>
11#include <linux/hugetlb.h>
12#include <linux/shm.h>
13#include <linux/ksm.h>
14#include <linux/mman.h>
15#include <linux/swap.h>
16#include <linux/capability.h>
17#include <linux/fs.h>
18#include <linux/swapops.h>
19#include <linux/highmem.h>
20#include <linux/security.h>
21#include <linux/syscalls.h>
22#include <linux/mmu_notifier.h>
23#include <linux/sched/sysctl.h>
24
25#include <asm/uaccess.h>
26#include <asm/cacheflush.h>
27#include <asm/tlbflush.h>
28
29#include "internal.h"
30
31static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
32{
33 pgd_t *pgd;
34 pud_t *pud;
35 pmd_t *pmd;
36
37 pgd = pgd_offset(mm, addr);
38 if (pgd_none_or_clear_bad(pgd))
39 return NULL;
40
41 pud = pud_offset(pgd, addr);
42 if (pud_none_or_clear_bad(pud))
43 return NULL;
44
45 pmd = pmd_offset(pud, addr);
46 if (pmd_none(*pmd))
47 return NULL;
48
49 return pmd;
50}
51
52static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
53 unsigned long addr)
54{
55 pgd_t *pgd;
56 pud_t *pud;
57 pmd_t *pmd;
58
59 pgd = pgd_offset(mm, addr);
60 pud = pud_alloc(mm, pgd, addr);
61 if (!pud)
62 return NULL;
63
64 pmd = pmd_alloc(mm, pud, addr);
65 if (!pmd)
66 return NULL;
67
68 VM_BUG_ON(pmd_trans_huge(*pmd));
69
70 return pmd;
71}
72
73static pte_t move_soft_dirty_pte(pte_t pte)
74{
75 /*
76 * Set soft dirty bit so we can notice
77 * in userspace the ptes were moved.
78 */
79#ifdef CONFIG_MEM_SOFT_DIRTY
80 if (pte_present(pte))
81 pte = pte_mksoft_dirty(pte);
82 else if (is_swap_pte(pte))
83 pte = pte_swp_mksoft_dirty(pte);
84 else if (pte_file(pte))
85 pte = pte_file_mksoft_dirty(pte);
86#endif
87 return pte;
88}
89
90static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
91 unsigned long old_addr, unsigned long old_end,
92 struct vm_area_struct *new_vma, pmd_t *new_pmd,
93 unsigned long new_addr, bool need_rmap_locks)
94{
95 struct address_space *mapping = NULL;
96 struct anon_vma *anon_vma = NULL;
97 struct mm_struct *mm = vma->vm_mm;
98 pte_t *old_pte, *new_pte, pte;
99 spinlock_t *old_ptl, *new_ptl;
100
101 /*
102 * When need_rmap_locks is true, we take the i_mmap_mutex and anon_vma
103 * locks to ensure that rmap will always observe either the old or the
104 * new ptes. This is the easiest way to avoid races with
105 * truncate_pagecache(), page migration, etc...
106 *
107 * When need_rmap_locks is false, we use other ways to avoid
108 * such races:
109 *
110 * - During exec() shift_arg_pages(), we use a specially tagged vma
111 * which rmap call sites look for using is_vma_temporary_stack().
112 *
113 * - During mremap(), new_vma is often known to be placed after vma
114 * in rmap traversal order. This ensures rmap will always observe
115 * either the old pte, or the new pte, or both (the page table locks
116 * serialize access to individual ptes, but only rmap traversal
117 * order guarantees that we won't miss both the old and new ptes).
118 */
119 if (need_rmap_locks) {
120 if (vma->vm_file) {
121 mapping = vma->vm_file->f_mapping;
122 mutex_lock(&mapping->i_mmap_mutex);
123 }
124 if (vma->anon_vma) {
125 anon_vma = vma->anon_vma;
126 anon_vma_lock_write(anon_vma);
127 }
128 }
129
130 /*
131 * We don't have to worry about the ordering of src and dst
132 * pte locks because exclusive mmap_sem prevents deadlock.
133 */
134 old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
135 new_pte = pte_offset_map(new_pmd, new_addr);
136 new_ptl = pte_lockptr(mm, new_pmd);
137 if (new_ptl != old_ptl)
138 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
139 arch_enter_lazy_mmu_mode();
140
141 for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
142 new_pte++, new_addr += PAGE_SIZE) {
143 if (pte_none(*old_pte))
144 continue;
145 pte = ptep_get_and_clear(mm, old_addr, old_pte);
146 pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
147 pte = move_soft_dirty_pte(pte);
148 set_pte_at(mm, new_addr, new_pte, pte);
149 }
150
151 arch_leave_lazy_mmu_mode();
152 if (new_ptl != old_ptl)
153 spin_unlock(new_ptl);
154 pte_unmap(new_pte - 1);
155 pte_unmap_unlock(old_pte - 1, old_ptl);
156 if (anon_vma)
157 anon_vma_unlock_write(anon_vma);
158 if (mapping)
159 mutex_unlock(&mapping->i_mmap_mutex);
160}
161
162#define LATENCY_LIMIT (64 * PAGE_SIZE)
163
164unsigned long move_page_tables(struct vm_area_struct *vma,
165 unsigned long old_addr, struct vm_area_struct *new_vma,
166 unsigned long new_addr, unsigned long len,
167 bool need_rmap_locks)
168{
169 unsigned long extent, next, old_end;
170 pmd_t *old_pmd, *new_pmd;
171 bool need_flush = false;
172 unsigned long mmun_start; /* For mmu_notifiers */
173 unsigned long mmun_end; /* For mmu_notifiers */
174
175 old_end = old_addr + len;
176 flush_cache_range(vma, old_addr, old_end);
177
178 mmun_start = old_addr;
179 mmun_end = old_end;
180 mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
181
182 for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
183 cond_resched();
184 next = (old_addr + PMD_SIZE) & PMD_MASK;
185 /* even if next overflowed, extent below will be ok */
186 extent = next - old_addr;
187 if (extent > old_end - old_addr)
188 extent = old_end - old_addr;
189 old_pmd = get_old_pmd(vma->vm_mm, old_addr);
190 if (!old_pmd)
191 continue;
192 new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
193 if (!new_pmd)
194 break;
195 if (pmd_trans_huge(*old_pmd)) {
196 int err = 0;
197 if (extent == HPAGE_PMD_SIZE) {
198 VM_BUG_ON(vma->vm_file || !vma->anon_vma);
199 /* See comment in move_ptes() */
200 if (need_rmap_locks)
201 anon_vma_lock_write(vma->anon_vma);
202 err = move_huge_pmd(vma, new_vma, old_addr,
203 new_addr, old_end,
204 old_pmd, new_pmd);
205 if (need_rmap_locks)
206 anon_vma_unlock_write(vma->anon_vma);
207 }
208 if (err > 0) {
209 need_flush = true;
210 continue;
211 } else if (!err) {
212 split_huge_page_pmd(vma, old_addr, old_pmd);
213 }
214 VM_BUG_ON(pmd_trans_huge(*old_pmd));
215 }
216 if (pmd_none(*new_pmd) && __pte_alloc(new_vma->vm_mm, new_vma,
217 new_pmd, new_addr))
218 break;
219 next = (new_addr + PMD_SIZE) & PMD_MASK;
220 if (extent > next - new_addr)
221 extent = next - new_addr;
222 if (extent > LATENCY_LIMIT)
223 extent = LATENCY_LIMIT;
224 move_ptes(vma, old_pmd, old_addr, old_addr + extent,
225 new_vma, new_pmd, new_addr, need_rmap_locks);
226 need_flush = true;
227 }
228 if (likely(need_flush))
229 flush_tlb_range(vma, old_end-len, old_addr);
230
231 mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
232
233 return len + old_addr - old_end; /* how much done */
234}
235
236static unsigned long move_vma(struct vm_area_struct *vma,
237 unsigned long old_addr, unsigned long old_len,
238 unsigned long new_len, unsigned long new_addr, bool *locked)
239{
240 struct mm_struct *mm = vma->vm_mm;
241 struct vm_area_struct *new_vma;
242 unsigned long vm_flags = vma->vm_flags;
243 unsigned long new_pgoff;
244 unsigned long moved_len;
245 unsigned long excess = 0;
246 unsigned long hiwater_vm;
247 int split = 0;
248 int err;
249 bool need_rmap_locks;
250
251 /*
252 * We'd prefer to avoid failure later on in do_munmap:
253 * which may split one vma into three before unmapping.
254 */
255 if (mm->map_count >= sysctl_max_map_count - 3)
256 return -ENOMEM;
257
258 /*
259 * Advise KSM to break any KSM pages in the area to be moved:
260 * it would be confusing if they were to turn up at the new
261 * location, where they happen to coincide with different KSM
262 * pages recently unmapped. But leave vma->vm_flags as it was,
263 * so KSM can come around to merge on vma and new_vma afterwards.
264 */
265 err = ksm_madvise(vma, old_addr, old_addr + old_len,
266 MADV_UNMERGEABLE, &vm_flags);
267 if (err)
268 return err;
269
270 new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
271 new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff,
272 &need_rmap_locks);
273 if (!new_vma)
274 return -ENOMEM;
275
276 moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len,
277 need_rmap_locks);
278 if (moved_len < old_len) {
279 /*
280 * On error, move entries back from new area to old,
281 * which will succeed since page tables still there,
282 * and then proceed to unmap new area instead of old.
283 */
284 move_page_tables(new_vma, new_addr, vma, old_addr, moved_len,
285 true);
286 vma = new_vma;
287 old_len = new_len;
288 old_addr = new_addr;
289 new_addr = -ENOMEM;
290 }
291
292 /* Conceal VM_ACCOUNT so old reservation is not undone */
293 if (vm_flags & VM_ACCOUNT) {
294 vma->vm_flags &= ~VM_ACCOUNT;
295 excess = vma->vm_end - vma->vm_start - old_len;
296 if (old_addr > vma->vm_start &&
297 old_addr + old_len < vma->vm_end)
298 split = 1;
299 }
300
301 /*
302 * If we failed to move page tables we still do total_vm increment
303 * since do_munmap() will decrement it by old_len == new_len.
304 *
305 * Since total_vm is about to be raised artificially high for a
306 * moment, we need to restore high watermark afterwards: if stats
307 * are taken meanwhile, total_vm and hiwater_vm appear too high.
308 * If this were a serious issue, we'd add a flag to do_munmap().
309 */
310 hiwater_vm = mm->hiwater_vm;
311 vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
312
313 if (do_munmap(mm, old_addr, old_len) < 0) {
314 /* OOM: unable to split vma, just get accounts right */
315 vm_unacct_memory(excess >> PAGE_SHIFT);
316 excess = 0;
317 }
318 mm->hiwater_vm = hiwater_vm;
319
320 /* Restore VM_ACCOUNT if one or two pieces of vma left */
321 if (excess) {
322 vma->vm_flags |= VM_ACCOUNT;
323 if (split)
324 vma->vm_next->vm_flags |= VM_ACCOUNT;
325 }
326
327 if (vm_flags & VM_LOCKED) {
328 mm->locked_vm += new_len >> PAGE_SHIFT;
329 *locked = true;
330 }
331
332 return new_addr;
333}
334
335static struct vm_area_struct *vma_to_resize(unsigned long addr,
336 unsigned long old_len, unsigned long new_len, unsigned long *p)
337{
338 struct mm_struct *mm = current->mm;
339 struct vm_area_struct *vma = find_vma(mm, addr);
340
341 if (!vma || vma->vm_start > addr)
342 goto Efault;
343
344 if (is_vm_hugetlb_page(vma))
345 goto Einval;
346
347 /* We can't remap across vm area boundaries */
348 if (old_len > vma->vm_end - addr)
349 goto Efault;
350
351 /* Need to be careful about a growing mapping */
352 if (new_len > old_len) {
353 unsigned long pgoff;
354
355 if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
356 goto Efault;
357 pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
358 pgoff += vma->vm_pgoff;
359 if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
360 goto Einval;
361 }
362
363 if (vma->vm_flags & VM_LOCKED) {
364 unsigned long locked, lock_limit;
365 locked = mm->locked_vm << PAGE_SHIFT;
366 lock_limit = rlimit(RLIMIT_MEMLOCK);
367 locked += new_len - old_len;
368 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
369 goto Eagain;
370 }
371
372 if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT))
373 goto Enomem;
374
375 if (vma->vm_flags & VM_ACCOUNT) {
376 unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;
377 if (security_vm_enough_memory_mm(mm, charged))
378 goto Efault;
379 *p = charged;
380 }
381
382 return vma;
383
384Efault: /* very odd choice for most of the cases, but... */
385 return ERR_PTR(-EFAULT);
386Einval:
387 return ERR_PTR(-EINVAL);
388Enomem:
389 return ERR_PTR(-ENOMEM);
390Eagain:
391 return ERR_PTR(-EAGAIN);
392}
393
394static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
395 unsigned long new_addr, unsigned long new_len, bool *locked)
396{
397 struct mm_struct *mm = current->mm;
398 struct vm_area_struct *vma;
399 unsigned long ret = -EINVAL;
400 unsigned long charged = 0;
401 unsigned long map_flags;
402
403 if (new_addr & ~PAGE_MASK)
404 goto out;
405
406 if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
407 goto out;
408
409 /* Check if the location we're moving into overlaps the
410 * old location at all, and fail if it does.
411 */
412 if ((new_addr <= addr) && (new_addr+new_len) > addr)
413 goto out;
414
415 if ((addr <= new_addr) && (addr+old_len) > new_addr)
416 goto out;
417
418 ret = do_munmap(mm, new_addr, new_len);
419 if (ret)
420 goto out;
421
422 if (old_len >= new_len) {
423 ret = do_munmap(mm, addr+new_len, old_len - new_len);
424 if (ret && old_len != new_len)
425 goto out;
426 old_len = new_len;
427 }
428
429 vma = vma_to_resize(addr, old_len, new_len, &charged);
430 if (IS_ERR(vma)) {
431 ret = PTR_ERR(vma);
432 goto out;
433 }
434
435 map_flags = MAP_FIXED;
436 if (vma->vm_flags & VM_MAYSHARE)
437 map_flags |= MAP_SHARED;
438
439 ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
440 ((addr - vma->vm_start) >> PAGE_SHIFT),
441 map_flags);
442 if (ret & ~PAGE_MASK)
443 goto out1;
444
445 ret = move_vma(vma, addr, old_len, new_len, new_addr, locked);
446 if (!(ret & ~PAGE_MASK))
447 goto out;
448out1:
449 vm_unacct_memory(charged);
450
451out:
452 return ret;
453}
454
455static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
456{
457 unsigned long end = vma->vm_end + delta;
458 if (end < vma->vm_end) /* overflow */
459 return 0;
460 if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */
461 return 0;
462 if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
463 0, MAP_FIXED) & ~PAGE_MASK)
464 return 0;
465 return 1;
466}
467
468/*
469 * Expand (or shrink) an existing mapping, potentially moving it at the
470 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
471 *
472 * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
473 * This option implies MREMAP_MAYMOVE.
474 */
475SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
476 unsigned long, new_len, unsigned long, flags,
477 unsigned long, new_addr)
478{
479 struct mm_struct *mm = current->mm;
480 struct vm_area_struct *vma;
481 unsigned long ret = -EINVAL;
482 unsigned long charged = 0;
483 bool locked = false;
484
485 if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
486 return ret;
487
488 if (flags & MREMAP_FIXED && !(flags & MREMAP_MAYMOVE))
489 return ret;
490
491 if (addr & ~PAGE_MASK)
492 return ret;
493
494 old_len = PAGE_ALIGN(old_len);
495 new_len = PAGE_ALIGN(new_len);
496
497 /*
498 * We allow a zero old-len as a special case
499 * for DOS-emu "duplicate shm area" thing. But
500 * a zero new-len is nonsensical.
501 */
502 if (!new_len)
503 return ret;
504
505 down_write(¤t->mm->mmap_sem);
506
507 if (flags & MREMAP_FIXED) {
508 ret = mremap_to(addr, old_len, new_addr, new_len,
509 &locked);
510 goto out;
511 }
512
513 /*
514 * Always allow a shrinking remap: that just unmaps
515 * the unnecessary pages..
516 * do_munmap does all the needed commit accounting
517 */
518 if (old_len >= new_len) {
519 ret = do_munmap(mm, addr+new_len, old_len - new_len);
520 if (ret && old_len != new_len)
521 goto out;
522 ret = addr;
523 goto out;
524 }
525
526 /*
527 * Ok, we need to grow..
528 */
529 vma = vma_to_resize(addr, old_len, new_len, &charged);
530 if (IS_ERR(vma)) {
531 ret = PTR_ERR(vma);
532 goto out;
533 }
534
535 /* old_len exactly to the end of the area..
536 */
537 if (old_len == vma->vm_end - addr) {
538 /* can we just expand the current mapping? */
539 if (vma_expandable(vma, new_len - old_len)) {
540 int pages = (new_len - old_len) >> PAGE_SHIFT;
541
542 if (vma_adjust(vma, vma->vm_start, addr + new_len,
543 vma->vm_pgoff, NULL)) {
544 ret = -ENOMEM;
545 goto out;
546 }
547
548 vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
549 if (vma->vm_flags & VM_LOCKED) {
550 mm->locked_vm += pages;
551 locked = true;
552 new_addr = addr;
553 }
554 ret = addr;
555 goto out;
556 }
557 }
558
559 /*
560 * We weren't able to just expand or shrink the area,
561 * we need to create a new one and move it..
562 */
563 ret = -ENOMEM;
564 if (flags & MREMAP_MAYMOVE) {
565 unsigned long map_flags = 0;
566 if (vma->vm_flags & VM_MAYSHARE)
567 map_flags |= MAP_SHARED;
568
569 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
570 vma->vm_pgoff +
571 ((addr - vma->vm_start) >> PAGE_SHIFT),
572 map_flags);
573 if (new_addr & ~PAGE_MASK) {
574 ret = new_addr;
575 goto out;
576 }
577
578 ret = move_vma(vma, addr, old_len, new_len, new_addr, &locked);
579 }
580out:
581 if (ret & ~PAGE_MASK)
582 vm_unacct_memory(charged);
583 up_write(¤t->mm->mmap_sem);
584 if (locked && new_len > old_len)
585 mm_populate(new_addr + old_len, new_len - old_len);
586 return ret;
587}
1/*
2 * mm/mremap.c
3 *
4 * (C) Copyright 1996 Linus Torvalds
5 *
6 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
7 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
8 */
9
10#include <linux/mm.h>
11#include <linux/hugetlb.h>
12#include <linux/shm.h>
13#include <linux/ksm.h>
14#include <linux/mman.h>
15#include <linux/swap.h>
16#include <linux/capability.h>
17#include <linux/fs.h>
18#include <linux/highmem.h>
19#include <linux/security.h>
20#include <linux/syscalls.h>
21#include <linux/mmu_notifier.h>
22
23#include <asm/uaccess.h>
24#include <asm/cacheflush.h>
25#include <asm/tlbflush.h>
26
27#include "internal.h"
28
29static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
30{
31 pgd_t *pgd;
32 pud_t *pud;
33 pmd_t *pmd;
34
35 pgd = pgd_offset(mm, addr);
36 if (pgd_none_or_clear_bad(pgd))
37 return NULL;
38
39 pud = pud_offset(pgd, addr);
40 if (pud_none_or_clear_bad(pud))
41 return NULL;
42
43 pmd = pmd_offset(pud, addr);
44 if (pmd_none(*pmd))
45 return NULL;
46
47 return pmd;
48}
49
50static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
51 unsigned long addr)
52{
53 pgd_t *pgd;
54 pud_t *pud;
55 pmd_t *pmd;
56
57 pgd = pgd_offset(mm, addr);
58 pud = pud_alloc(mm, pgd, addr);
59 if (!pud)
60 return NULL;
61
62 pmd = pmd_alloc(mm, pud, addr);
63 if (!pmd)
64 return NULL;
65
66 VM_BUG_ON(pmd_trans_huge(*pmd));
67
68 return pmd;
69}
70
71static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
72 unsigned long old_addr, unsigned long old_end,
73 struct vm_area_struct *new_vma, pmd_t *new_pmd,
74 unsigned long new_addr)
75{
76 struct address_space *mapping = NULL;
77 struct mm_struct *mm = vma->vm_mm;
78 pte_t *old_pte, *new_pte, pte;
79 spinlock_t *old_ptl, *new_ptl;
80
81 if (vma->vm_file) {
82 /*
83 * Subtle point from Rajesh Venkatasubramanian: before
84 * moving file-based ptes, we must lock truncate_pagecache
85 * out, since it might clean the dst vma before the src vma,
86 * and we propagate stale pages into the dst afterward.
87 */
88 mapping = vma->vm_file->f_mapping;
89 mutex_lock(&mapping->i_mmap_mutex);
90 }
91
92 /*
93 * We don't have to worry about the ordering of src and dst
94 * pte locks because exclusive mmap_sem prevents deadlock.
95 */
96 old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
97 new_pte = pte_offset_map(new_pmd, new_addr);
98 new_ptl = pte_lockptr(mm, new_pmd);
99 if (new_ptl != old_ptl)
100 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
101 arch_enter_lazy_mmu_mode();
102
103 for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
104 new_pte++, new_addr += PAGE_SIZE) {
105 if (pte_none(*old_pte))
106 continue;
107 pte = ptep_get_and_clear(mm, old_addr, old_pte);
108 pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
109 set_pte_at(mm, new_addr, new_pte, pte);
110 }
111
112 arch_leave_lazy_mmu_mode();
113 if (new_ptl != old_ptl)
114 spin_unlock(new_ptl);
115 pte_unmap(new_pte - 1);
116 pte_unmap_unlock(old_pte - 1, old_ptl);
117 if (mapping)
118 mutex_unlock(&mapping->i_mmap_mutex);
119}
120
121#define LATENCY_LIMIT (64 * PAGE_SIZE)
122
123unsigned long move_page_tables(struct vm_area_struct *vma,
124 unsigned long old_addr, struct vm_area_struct *new_vma,
125 unsigned long new_addr, unsigned long len)
126{
127 unsigned long extent, next, old_end;
128 pmd_t *old_pmd, *new_pmd;
129 bool need_flush = false;
130
131 old_end = old_addr + len;
132 flush_cache_range(vma, old_addr, old_end);
133
134 mmu_notifier_invalidate_range_start(vma->vm_mm, old_addr, old_end);
135
136 for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
137 cond_resched();
138 next = (old_addr + PMD_SIZE) & PMD_MASK;
139 /* even if next overflowed, extent below will be ok */
140 extent = next - old_addr;
141 if (extent > old_end - old_addr)
142 extent = old_end - old_addr;
143 old_pmd = get_old_pmd(vma->vm_mm, old_addr);
144 if (!old_pmd)
145 continue;
146 new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
147 if (!new_pmd)
148 break;
149 if (pmd_trans_huge(*old_pmd)) {
150 int err = 0;
151 if (extent == HPAGE_PMD_SIZE)
152 err = move_huge_pmd(vma, new_vma, old_addr,
153 new_addr, old_end,
154 old_pmd, new_pmd);
155 if (err > 0) {
156 need_flush = true;
157 continue;
158 } else if (!err) {
159 split_huge_page_pmd(vma->vm_mm, old_pmd);
160 }
161 VM_BUG_ON(pmd_trans_huge(*old_pmd));
162 }
163 if (pmd_none(*new_pmd) && __pte_alloc(new_vma->vm_mm, new_vma,
164 new_pmd, new_addr))
165 break;
166 next = (new_addr + PMD_SIZE) & PMD_MASK;
167 if (extent > next - new_addr)
168 extent = next - new_addr;
169 if (extent > LATENCY_LIMIT)
170 extent = LATENCY_LIMIT;
171 move_ptes(vma, old_pmd, old_addr, old_addr + extent,
172 new_vma, new_pmd, new_addr);
173 need_flush = true;
174 }
175 if (likely(need_flush))
176 flush_tlb_range(vma, old_end-len, old_addr);
177
178 mmu_notifier_invalidate_range_end(vma->vm_mm, old_end-len, old_end);
179
180 return len + old_addr - old_end; /* how much done */
181}
182
183static unsigned long move_vma(struct vm_area_struct *vma,
184 unsigned long old_addr, unsigned long old_len,
185 unsigned long new_len, unsigned long new_addr)
186{
187 struct mm_struct *mm = vma->vm_mm;
188 struct vm_area_struct *new_vma;
189 unsigned long vm_flags = vma->vm_flags;
190 unsigned long new_pgoff;
191 unsigned long moved_len;
192 unsigned long excess = 0;
193 unsigned long hiwater_vm;
194 int split = 0;
195 int err;
196
197 /*
198 * We'd prefer to avoid failure later on in do_munmap:
199 * which may split one vma into three before unmapping.
200 */
201 if (mm->map_count >= sysctl_max_map_count - 3)
202 return -ENOMEM;
203
204 /*
205 * Advise KSM to break any KSM pages in the area to be moved:
206 * it would be confusing if they were to turn up at the new
207 * location, where they happen to coincide with different KSM
208 * pages recently unmapped. But leave vma->vm_flags as it was,
209 * so KSM can come around to merge on vma and new_vma afterwards.
210 */
211 err = ksm_madvise(vma, old_addr, old_addr + old_len,
212 MADV_UNMERGEABLE, &vm_flags);
213 if (err)
214 return err;
215
216 new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
217 new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff);
218 if (!new_vma)
219 return -ENOMEM;
220
221 moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len);
222 if (moved_len < old_len) {
223 /*
224 * Before moving the page tables from the new vma to
225 * the old vma, we need to be sure the old vma is
226 * queued after new vma in the same_anon_vma list to
227 * prevent SMP races with rmap_walk (that could lead
228 * rmap_walk to miss some page table).
229 */
230 anon_vma_moveto_tail(vma);
231
232 /*
233 * On error, move entries back from new area to old,
234 * which will succeed since page tables still there,
235 * and then proceed to unmap new area instead of old.
236 */
237 move_page_tables(new_vma, new_addr, vma, old_addr, moved_len);
238 vma = new_vma;
239 old_len = new_len;
240 old_addr = new_addr;
241 new_addr = -ENOMEM;
242 }
243
244 /* Conceal VM_ACCOUNT so old reservation is not undone */
245 if (vm_flags & VM_ACCOUNT) {
246 vma->vm_flags &= ~VM_ACCOUNT;
247 excess = vma->vm_end - vma->vm_start - old_len;
248 if (old_addr > vma->vm_start &&
249 old_addr + old_len < vma->vm_end)
250 split = 1;
251 }
252
253 /*
254 * If we failed to move page tables we still do total_vm increment
255 * since do_munmap() will decrement it by old_len == new_len.
256 *
257 * Since total_vm is about to be raised artificially high for a
258 * moment, we need to restore high watermark afterwards: if stats
259 * are taken meanwhile, total_vm and hiwater_vm appear too high.
260 * If this were a serious issue, we'd add a flag to do_munmap().
261 */
262 hiwater_vm = mm->hiwater_vm;
263 mm->total_vm += new_len >> PAGE_SHIFT;
264 vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
265
266 if (do_munmap(mm, old_addr, old_len) < 0) {
267 /* OOM: unable to split vma, just get accounts right */
268 vm_unacct_memory(excess >> PAGE_SHIFT);
269 excess = 0;
270 }
271 mm->hiwater_vm = hiwater_vm;
272
273 /* Restore VM_ACCOUNT if one or two pieces of vma left */
274 if (excess) {
275 vma->vm_flags |= VM_ACCOUNT;
276 if (split)
277 vma->vm_next->vm_flags |= VM_ACCOUNT;
278 }
279
280 if (vm_flags & VM_LOCKED) {
281 mm->locked_vm += new_len >> PAGE_SHIFT;
282 if (new_len > old_len)
283 mlock_vma_pages_range(new_vma, new_addr + old_len,
284 new_addr + new_len);
285 }
286
287 return new_addr;
288}
289
290static struct vm_area_struct *vma_to_resize(unsigned long addr,
291 unsigned long old_len, unsigned long new_len, unsigned long *p)
292{
293 struct mm_struct *mm = current->mm;
294 struct vm_area_struct *vma = find_vma(mm, addr);
295
296 if (!vma || vma->vm_start > addr)
297 goto Efault;
298
299 if (is_vm_hugetlb_page(vma))
300 goto Einval;
301
302 /* We can't remap across vm area boundaries */
303 if (old_len > vma->vm_end - addr)
304 goto Efault;
305
306 /* Need to be careful about a growing mapping */
307 if (new_len > old_len) {
308 unsigned long pgoff;
309
310 if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
311 goto Efault;
312 pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
313 pgoff += vma->vm_pgoff;
314 if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
315 goto Einval;
316 }
317
318 if (vma->vm_flags & VM_LOCKED) {
319 unsigned long locked, lock_limit;
320 locked = mm->locked_vm << PAGE_SHIFT;
321 lock_limit = rlimit(RLIMIT_MEMLOCK);
322 locked += new_len - old_len;
323 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
324 goto Eagain;
325 }
326
327 if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT))
328 goto Enomem;
329
330 if (vma->vm_flags & VM_ACCOUNT) {
331 unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;
332 if (security_vm_enough_memory_mm(mm, charged))
333 goto Efault;
334 *p = charged;
335 }
336
337 return vma;
338
339Efault: /* very odd choice for most of the cases, but... */
340 return ERR_PTR(-EFAULT);
341Einval:
342 return ERR_PTR(-EINVAL);
343Enomem:
344 return ERR_PTR(-ENOMEM);
345Eagain:
346 return ERR_PTR(-EAGAIN);
347}
348
349static unsigned long mremap_to(unsigned long addr,
350 unsigned long old_len, unsigned long new_addr,
351 unsigned long new_len)
352{
353 struct mm_struct *mm = current->mm;
354 struct vm_area_struct *vma;
355 unsigned long ret = -EINVAL;
356 unsigned long charged = 0;
357 unsigned long map_flags;
358
359 if (new_addr & ~PAGE_MASK)
360 goto out;
361
362 if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
363 goto out;
364
365 /* Check if the location we're moving into overlaps the
366 * old location at all, and fail if it does.
367 */
368 if ((new_addr <= addr) && (new_addr+new_len) > addr)
369 goto out;
370
371 if ((addr <= new_addr) && (addr+old_len) > new_addr)
372 goto out;
373
374 ret = do_munmap(mm, new_addr, new_len);
375 if (ret)
376 goto out;
377
378 if (old_len >= new_len) {
379 ret = do_munmap(mm, addr+new_len, old_len - new_len);
380 if (ret && old_len != new_len)
381 goto out;
382 old_len = new_len;
383 }
384
385 vma = vma_to_resize(addr, old_len, new_len, &charged);
386 if (IS_ERR(vma)) {
387 ret = PTR_ERR(vma);
388 goto out;
389 }
390
391 map_flags = MAP_FIXED;
392 if (vma->vm_flags & VM_MAYSHARE)
393 map_flags |= MAP_SHARED;
394
395 ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
396 ((addr - vma->vm_start) >> PAGE_SHIFT),
397 map_flags);
398 if (ret & ~PAGE_MASK)
399 goto out1;
400
401 ret = move_vma(vma, addr, old_len, new_len, new_addr);
402 if (!(ret & ~PAGE_MASK))
403 goto out;
404out1:
405 vm_unacct_memory(charged);
406
407out:
408 return ret;
409}
410
411static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
412{
413 unsigned long end = vma->vm_end + delta;
414 if (end < vma->vm_end) /* overflow */
415 return 0;
416 if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */
417 return 0;
418 if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
419 0, MAP_FIXED) & ~PAGE_MASK)
420 return 0;
421 return 1;
422}
423
424/*
425 * Expand (or shrink) an existing mapping, potentially moving it at the
426 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
427 *
428 * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
429 * This option implies MREMAP_MAYMOVE.
430 */
431SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
432 unsigned long, new_len, unsigned long, flags,
433 unsigned long, new_addr)
434{
435 struct mm_struct *mm = current->mm;
436 struct vm_area_struct *vma;
437 unsigned long ret = -EINVAL;
438 unsigned long charged = 0;
439
440 down_write(¤t->mm->mmap_sem);
441
442 if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
443 goto out;
444
445 if (addr & ~PAGE_MASK)
446 goto out;
447
448 old_len = PAGE_ALIGN(old_len);
449 new_len = PAGE_ALIGN(new_len);
450
451 /*
452 * We allow a zero old-len as a special case
453 * for DOS-emu "duplicate shm area" thing. But
454 * a zero new-len is nonsensical.
455 */
456 if (!new_len)
457 goto out;
458
459 if (flags & MREMAP_FIXED) {
460 if (flags & MREMAP_MAYMOVE)
461 ret = mremap_to(addr, old_len, new_addr, new_len);
462 goto out;
463 }
464
465 /*
466 * Always allow a shrinking remap: that just unmaps
467 * the unnecessary pages..
468 * do_munmap does all the needed commit accounting
469 */
470 if (old_len >= new_len) {
471 ret = do_munmap(mm, addr+new_len, old_len - new_len);
472 if (ret && old_len != new_len)
473 goto out;
474 ret = addr;
475 goto out;
476 }
477
478 /*
479 * Ok, we need to grow..
480 */
481 vma = vma_to_resize(addr, old_len, new_len, &charged);
482 if (IS_ERR(vma)) {
483 ret = PTR_ERR(vma);
484 goto out;
485 }
486
487 /* old_len exactly to the end of the area..
488 */
489 if (old_len == vma->vm_end - addr) {
490 /* can we just expand the current mapping? */
491 if (vma_expandable(vma, new_len - old_len)) {
492 int pages = (new_len - old_len) >> PAGE_SHIFT;
493
494 if (vma_adjust(vma, vma->vm_start, addr + new_len,
495 vma->vm_pgoff, NULL)) {
496 ret = -ENOMEM;
497 goto out;
498 }
499
500 mm->total_vm += pages;
501 vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
502 if (vma->vm_flags & VM_LOCKED) {
503 mm->locked_vm += pages;
504 mlock_vma_pages_range(vma, addr + old_len,
505 addr + new_len);
506 }
507 ret = addr;
508 goto out;
509 }
510 }
511
512 /*
513 * We weren't able to just expand or shrink the area,
514 * we need to create a new one and move it..
515 */
516 ret = -ENOMEM;
517 if (flags & MREMAP_MAYMOVE) {
518 unsigned long map_flags = 0;
519 if (vma->vm_flags & VM_MAYSHARE)
520 map_flags |= MAP_SHARED;
521
522 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
523 vma->vm_pgoff +
524 ((addr - vma->vm_start) >> PAGE_SHIFT),
525 map_flags);
526 if (new_addr & ~PAGE_MASK) {
527 ret = new_addr;
528 goto out;
529 }
530
531 ret = move_vma(vma, addr, old_len, new_len, new_addr);
532 }
533out:
534 if (ret & ~PAGE_MASK)
535 vm_unacct_memory(charged);
536 up_write(¤t->mm->mmap_sem);
537 return ret;
538}