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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/uaccess.h>
24#include <linux/mm-arch-hooks.h>
25
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
77
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#endif
85 return pte;
86}
87
88static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
89 unsigned long old_addr, unsigned long old_end,
90 struct vm_area_struct *new_vma, pmd_t *new_pmd,
91 unsigned long new_addr, bool need_rmap_locks)
92{
93 struct address_space *mapping = NULL;
94 struct anon_vma *anon_vma = NULL;
95 struct mm_struct *mm = vma->vm_mm;
96 pte_t *old_pte, *new_pte, pte;
97 spinlock_t *old_ptl, *new_ptl;
98
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113
114
115
116
117 if (need_rmap_locks) {
118 if (vma->vm_file) {
119 mapping = vma->vm_file->f_mapping;
120 i_mmap_lock_write(mapping);
121 }
122 if (vma->anon_vma) {
123 anon_vma = vma->anon_vma;
124 anon_vma_lock_write(anon_vma);
125 }
126 }
127
128
129
130
131
132 old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
133 new_pte = pte_offset_map(new_pmd, new_addr);
134 new_ptl = pte_lockptr(mm, new_pmd);
135 if (new_ptl != old_ptl)
136 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
137 arch_enter_lazy_mmu_mode();
138
139 for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
140 new_pte++, new_addr += PAGE_SIZE) {
141 if (pte_none(*old_pte))
142 continue;
143 pte = ptep_get_and_clear(mm, old_addr, old_pte);
144 pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
145 pte = move_soft_dirty_pte(pte);
146 set_pte_at(mm, new_addr, new_pte, pte);
147 }
148
149 arch_leave_lazy_mmu_mode();
150 if (new_ptl != old_ptl)
151 spin_unlock(new_ptl);
152 pte_unmap(new_pte - 1);
153 pte_unmap_unlock(old_pte - 1, old_ptl);
154 if (anon_vma)
155 anon_vma_unlock_write(anon_vma);
156 if (mapping)
157 i_mmap_unlock_write(mapping);
158}
159
160#define LATENCY_LIMIT (64 * PAGE_SIZE)
161
162unsigned long move_page_tables(struct vm_area_struct *vma,
163 unsigned long old_addr, struct vm_area_struct *new_vma,
164 unsigned long new_addr, unsigned long len,
165 bool need_rmap_locks)
166{
167 unsigned long extent, next, old_end;
168 pmd_t *old_pmd, *new_pmd;
169 bool need_flush = false;
170 unsigned long mmun_start;
171 unsigned long mmun_end;
172
173 old_end = old_addr + len;
174 flush_cache_range(vma, old_addr, old_end);
175
176 mmun_start = old_addr;
177 mmun_end = old_end;
178 mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
179
180 for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
181 cond_resched();
182 next = (old_addr + PMD_SIZE) & PMD_MASK;
183
184 extent = next - old_addr;
185 if (extent > old_end - old_addr)
186 extent = old_end - old_addr;
187 old_pmd = get_old_pmd(vma->vm_mm, old_addr);
188 if (!old_pmd)
189 continue;
190 new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
191 if (!new_pmd)
192 break;
193 if (pmd_trans_huge(*old_pmd)) {
194 if (extent == HPAGE_PMD_SIZE) {
195 bool moved;
196 VM_BUG_ON_VMA(vma->vm_file || !vma->anon_vma,
197 vma);
198
199 if (need_rmap_locks)
200 anon_vma_lock_write(vma->anon_vma);
201 moved = move_huge_pmd(vma, new_vma, old_addr,
202 new_addr, old_end,
203 old_pmd, new_pmd);
204 if (need_rmap_locks)
205 anon_vma_unlock_write(vma->anon_vma);
206 if (moved) {
207 need_flush = true;
208 continue;
209 }
210 }
211 split_huge_pmd(vma, old_pmd, old_addr);
212 if (pmd_none(*old_pmd))
213 continue;
214 VM_BUG_ON(pmd_trans_huge(*old_pmd));
215 }
216 if (pte_alloc(new_vma->vm_mm, new_pmd, new_addr))
217 break;
218 next = (new_addr + PMD_SIZE) & PMD_MASK;
219 if (extent > next - new_addr)
220 extent = next - new_addr;
221 if (extent > LATENCY_LIMIT)
222 extent = LATENCY_LIMIT;
223 move_ptes(vma, old_pmd, old_addr, old_addr + extent,
224 new_vma, new_pmd, new_addr, need_rmap_locks);
225 need_flush = true;
226 }
227 if (likely(need_flush))
228 flush_tlb_range(vma, old_end-len, old_addr);
229
230 mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
231
232 return len + old_addr - old_end;
233}
234
235static unsigned long move_vma(struct vm_area_struct *vma,
236 unsigned long old_addr, unsigned long old_len,
237 unsigned long new_len, unsigned long new_addr, bool *locked)
238{
239 struct mm_struct *mm = vma->vm_mm;
240 struct vm_area_struct *new_vma;
241 unsigned long vm_flags = vma->vm_flags;
242 unsigned long new_pgoff;
243 unsigned long moved_len;
244 unsigned long excess = 0;
245 unsigned long hiwater_vm;
246 int split = 0;
247 int err;
248 bool need_rmap_locks;
249
250
251
252
253
254 if (mm->map_count >= sysctl_max_map_count - 3)
255 return -ENOMEM;
256
257
258
259
260
261
262
263
264 err = ksm_madvise(vma, old_addr, old_addr + old_len,
265 MADV_UNMERGEABLE, &vm_flags);
266 if (err)
267 return err;
268
269 new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
270 new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff,
271 &need_rmap_locks);
272 if (!new_vma)
273 return -ENOMEM;
274
275 moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len,
276 need_rmap_locks);
277 if (moved_len < old_len) {
278 err = -ENOMEM;
279 } else if (vma->vm_ops && vma->vm_ops->mremap) {
280 err = vma->vm_ops->mremap(new_vma);
281 }
282
283 if (unlikely(err)) {
284
285
286
287
288
289 move_page_tables(new_vma, new_addr, vma, old_addr, moved_len,
290 true);
291 vma = new_vma;
292 old_len = new_len;
293 old_addr = new_addr;
294 new_addr = err;
295 } else {
296 arch_remap(mm, old_addr, old_addr + old_len,
297 new_addr, new_addr + new_len);
298 }
299
300
301 if (vm_flags & VM_ACCOUNT) {
302 vma->vm_flags &= ~VM_ACCOUNT;
303 excess = vma->vm_end - vma->vm_start - old_len;
304 if (old_addr > vma->vm_start &&
305 old_addr + old_len < vma->vm_end)
306 split = 1;
307 }
308
309
310
311
312
313
314
315
316
317
318 hiwater_vm = mm->hiwater_vm;
319 vm_stat_account(mm, vma->vm_flags, new_len >> PAGE_SHIFT);
320
321
322 if (unlikely(vma->vm_flags & VM_PFNMAP))
323 untrack_pfn_moved(vma);
324
325 if (do_munmap(mm, old_addr, old_len) < 0) {
326
327 vm_unacct_memory(excess >> PAGE_SHIFT);
328 excess = 0;
329 }
330 mm->hiwater_vm = hiwater_vm;
331
332
333 if (excess) {
334 vma->vm_flags |= VM_ACCOUNT;
335 if (split)
336 vma->vm_next->vm_flags |= VM_ACCOUNT;
337 }
338
339 if (vm_flags & VM_LOCKED) {
340 mm->locked_vm += new_len >> PAGE_SHIFT;
341 *locked = true;
342 }
343
344 return new_addr;
345}
346
347static struct vm_area_struct *vma_to_resize(unsigned long addr,
348 unsigned long old_len, unsigned long new_len, unsigned long *p)
349{
350 struct mm_struct *mm = current->mm;
351 struct vm_area_struct *vma = find_vma(mm, addr);
352 unsigned long pgoff;
353
354 if (!vma || vma->vm_start > addr)
355 return ERR_PTR(-EFAULT);
356
357 if (is_vm_hugetlb_page(vma))
358 return ERR_PTR(-EINVAL);
359
360
361 if (old_len > vma->vm_end - addr)
362 return ERR_PTR(-EFAULT);
363
364 if (new_len == old_len)
365 return vma;
366
367
368 pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
369 pgoff += vma->vm_pgoff;
370 if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
371 return ERR_PTR(-EINVAL);
372
373 if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
374 return ERR_PTR(-EFAULT);
375
376 if (vma->vm_flags & VM_LOCKED) {
377 unsigned long locked, lock_limit;
378 locked = mm->locked_vm << PAGE_SHIFT;
379 lock_limit = rlimit(RLIMIT_MEMLOCK);
380 locked += new_len - old_len;
381 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
382 return ERR_PTR(-EAGAIN);
383 }
384
385 if (!may_expand_vm(mm, vma->vm_flags,
386 (new_len - old_len) >> PAGE_SHIFT))
387 return ERR_PTR(-ENOMEM);
388
389 if (vma->vm_flags & VM_ACCOUNT) {
390 unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;
391 if (security_vm_enough_memory_mm(mm, charged))
392 return ERR_PTR(-ENOMEM);
393 *p = charged;
394 }
395
396 return vma;
397}
398
399static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
400 unsigned long new_addr, unsigned long new_len, bool *locked)
401{
402 struct mm_struct *mm = current->mm;
403 struct vm_area_struct *vma;
404 unsigned long ret = -EINVAL;
405 unsigned long charged = 0;
406 unsigned long map_flags;
407
408 if (offset_in_page(new_addr))
409 goto out;
410
411 if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
412 goto out;
413
414
415 if (addr + old_len > new_addr && new_addr + new_len > 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 (offset_in_page(ret))
443 goto out1;
444
445 ret = move_vma(vma, addr, old_len, new_len, new_addr, locked);
446 if (!(offset_in_page(ret)))
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)
459 return 0;
460 if (vma->vm_next && vma->vm_next->vm_start < end)
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
470
471
472
473
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 (offset_in_page(addr))
492 return ret;
493
494 old_len = PAGE_ALIGN(old_len);
495 new_len = PAGE_ALIGN(new_len);
496
497
498
499
500
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
515
516
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
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
536
537 if (old_len == vma->vm_end - addr) {
538
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, 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
561
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 (offset_in_page(new_addr)) {
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 (offset_in_page(ret)) {
582 vm_unacct_memory(charged);
583 locked = 0;
584 }
585 up_write(¤t->mm->mmap_sem);
586 if (locked && new_len > old_len)
587 mm_populate(new_addr + old_len, new_len - old_len);
588 return ret;
589}
590