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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/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
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 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
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110
111
112
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114
115
116
117
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
132
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;
173 unsigned long mmun_end;
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
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 err = move_huge_pmd(vma, new_vma, old_addr,
199 new_addr, old_end,
200 old_pmd, new_pmd);
201 if (err > 0) {
202 need_flush = true;
203 continue;
204 } else if (!err) {
205 split_huge_page_pmd(vma, old_addr, old_pmd);
206 }
207 VM_BUG_ON(pmd_trans_huge(*old_pmd));
208 }
209 if (pmd_none(*new_pmd) && __pte_alloc(new_vma->vm_mm, new_vma,
210 new_pmd, new_addr))
211 break;
212 next = (new_addr + PMD_SIZE) & PMD_MASK;
213 if (extent > next - new_addr)
214 extent = next - new_addr;
215 if (extent > LATENCY_LIMIT)
216 extent = LATENCY_LIMIT;
217 move_ptes(vma, old_pmd, old_addr, old_addr + extent,
218 new_vma, new_pmd, new_addr, need_rmap_locks);
219 need_flush = true;
220 }
221 if (likely(need_flush))
222 flush_tlb_range(vma, old_end-len, old_addr);
223
224 mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
225
226 return len + old_addr - old_end;
227}
228
229static unsigned long move_vma(struct vm_area_struct *vma,
230 unsigned long old_addr, unsigned long old_len,
231 unsigned long new_len, unsigned long new_addr, bool *locked)
232{
233 struct mm_struct *mm = vma->vm_mm;
234 struct vm_area_struct *new_vma;
235 unsigned long vm_flags = vma->vm_flags;
236 unsigned long new_pgoff;
237 unsigned long moved_len;
238 unsigned long excess = 0;
239 unsigned long hiwater_vm;
240 int split = 0;
241 int err;
242 bool need_rmap_locks;
243
244
245
246
247
248 if (mm->map_count >= sysctl_max_map_count - 3)
249 return -ENOMEM;
250
251
252
253
254
255
256
257
258 err = ksm_madvise(vma, old_addr, old_addr + old_len,
259 MADV_UNMERGEABLE, &vm_flags);
260 if (err)
261 return err;
262
263 new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
264 new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff,
265 &need_rmap_locks);
266 if (!new_vma)
267 return -ENOMEM;
268
269 moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len,
270 need_rmap_locks);
271 if (moved_len < old_len) {
272
273
274
275
276
277 move_page_tables(new_vma, new_addr, vma, old_addr, moved_len,
278 true);
279 vma = new_vma;
280 old_len = new_len;
281 old_addr = new_addr;
282 new_addr = -ENOMEM;
283 }
284
285
286 if (vm_flags & VM_ACCOUNT) {
287 vma->vm_flags &= ~VM_ACCOUNT;
288 excess = vma->vm_end - vma->vm_start - old_len;
289 if (old_addr > vma->vm_start &&
290 old_addr + old_len < vma->vm_end)
291 split = 1;
292 }
293
294
295
296
297
298
299
300
301
302
303 hiwater_vm = mm->hiwater_vm;
304 vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
305
306 if (do_munmap(mm, old_addr, old_len) < 0) {
307
308 vm_unacct_memory(excess >> PAGE_SHIFT);
309 excess = 0;
310 }
311 mm->hiwater_vm = hiwater_vm;
312
313
314 if (excess) {
315 vma->vm_flags |= VM_ACCOUNT;
316 if (split)
317 vma->vm_next->vm_flags |= VM_ACCOUNT;
318 }
319
320 if (vm_flags & VM_LOCKED) {
321 mm->locked_vm += new_len >> PAGE_SHIFT;
322 *locked = true;
323 }
324
325 return new_addr;
326}
327
328static struct vm_area_struct *vma_to_resize(unsigned long addr,
329 unsigned long old_len, unsigned long new_len, unsigned long *p)
330{
331 struct mm_struct *mm = current->mm;
332 struct vm_area_struct *vma = find_vma(mm, addr);
333
334 if (!vma || vma->vm_start > addr)
335 goto Efault;
336
337 if (is_vm_hugetlb_page(vma))
338 goto Einval;
339
340
341 if (old_len > vma->vm_end - addr)
342 goto Efault;
343
344
345 if (new_len > old_len) {
346 unsigned long pgoff;
347
348 if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
349 goto Efault;
350 pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
351 pgoff += vma->vm_pgoff;
352 if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
353 goto Einval;
354 }
355
356 if (vma->vm_flags & VM_LOCKED) {
357 unsigned long locked, lock_limit;
358 locked = mm->locked_vm << PAGE_SHIFT;
359 lock_limit = rlimit(RLIMIT_MEMLOCK);
360 locked += new_len - old_len;
361 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
362 goto Eagain;
363 }
364
365 if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT))
366 goto Enomem;
367
368 if (vma->vm_flags & VM_ACCOUNT) {
369 unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;
370 if (security_vm_enough_memory_mm(mm, charged))
371 goto Efault;
372 *p = charged;
373 }
374
375 return vma;
376
377Efault:
378 return ERR_PTR(-EFAULT);
379Einval:
380 return ERR_PTR(-EINVAL);
381Enomem:
382 return ERR_PTR(-ENOMEM);
383Eagain:
384 return ERR_PTR(-EAGAIN);
385}
386
387static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
388 unsigned long new_addr, unsigned long new_len, bool *locked)
389{
390 struct mm_struct *mm = current->mm;
391 struct vm_area_struct *vma;
392 unsigned long ret = -EINVAL;
393 unsigned long charged = 0;
394 unsigned long map_flags;
395
396 if (new_addr & ~PAGE_MASK)
397 goto out;
398
399 if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
400 goto out;
401
402
403
404
405 if ((new_addr <= addr) && (new_addr+new_len) > addr)
406 goto out;
407
408 if ((addr <= new_addr) && (addr+old_len) > new_addr)
409 goto out;
410
411 ret = do_munmap(mm, new_addr, new_len);
412 if (ret)
413 goto out;
414
415 if (old_len >= new_len) {
416 ret = do_munmap(mm, addr+new_len, old_len - new_len);
417 if (ret && old_len != new_len)
418 goto out;
419 old_len = new_len;
420 }
421
422 vma = vma_to_resize(addr, old_len, new_len, &charged);
423 if (IS_ERR(vma)) {
424 ret = PTR_ERR(vma);
425 goto out;
426 }
427
428 map_flags = MAP_FIXED;
429 if (vma->vm_flags & VM_MAYSHARE)
430 map_flags |= MAP_SHARED;
431
432 ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
433 ((addr - vma->vm_start) >> PAGE_SHIFT),
434 map_flags);
435 if (ret & ~PAGE_MASK)
436 goto out1;
437
438 ret = move_vma(vma, addr, old_len, new_len, new_addr, locked);
439 if (!(ret & ~PAGE_MASK))
440 goto out;
441out1:
442 vm_unacct_memory(charged);
443
444out:
445 return ret;
446}
447
448static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
449{
450 unsigned long end = vma->vm_end + delta;
451 if (end < vma->vm_end)
452 return 0;
453 if (vma->vm_next && vma->vm_next->vm_start < end)
454 return 0;
455 if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
456 0, MAP_FIXED) & ~PAGE_MASK)
457 return 0;
458 return 1;
459}
460
461
462
463
464
465
466
467
468SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
469 unsigned long, new_len, unsigned long, flags,
470 unsigned long, new_addr)
471{
472 struct mm_struct *mm = current->mm;
473 struct vm_area_struct *vma;
474 unsigned long ret = -EINVAL;
475 unsigned long charged = 0;
476 bool locked = false;
477
478 if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
479 return ret;
480
481 if (flags & MREMAP_FIXED && !(flags & MREMAP_MAYMOVE))
482 return ret;
483
484 if (addr & ~PAGE_MASK)
485 return ret;
486
487 old_len = PAGE_ALIGN(old_len);
488 new_len = PAGE_ALIGN(new_len);
489
490
491
492
493
494
495 if (!new_len)
496 return ret;
497
498 down_write(¤t->mm->mmap_sem);
499
500 if (flags & MREMAP_FIXED) {
501 ret = mremap_to(addr, old_len, new_addr, new_len,
502 &locked);
503 goto out;
504 }
505
506
507
508
509
510
511 if (old_len >= new_len) {
512 ret = do_munmap(mm, addr+new_len, old_len - new_len);
513 if (ret && old_len != new_len)
514 goto out;
515 ret = addr;
516 goto out;
517 }
518
519
520
521
522 vma = vma_to_resize(addr, old_len, new_len, &charged);
523 if (IS_ERR(vma)) {
524 ret = PTR_ERR(vma);
525 goto out;
526 }
527
528
529
530 if (old_len == vma->vm_end - addr) {
531
532 if (vma_expandable(vma, new_len - old_len)) {
533 int pages = (new_len - old_len) >> PAGE_SHIFT;
534
535 if (vma_adjust(vma, vma->vm_start, addr + new_len,
536 vma->vm_pgoff, NULL)) {
537 ret = -ENOMEM;
538 goto out;
539 }
540
541 vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
542 if (vma->vm_flags & VM_LOCKED) {
543 mm->locked_vm += pages;
544 locked = true;
545 new_addr = addr;
546 }
547 ret = addr;
548 goto out;
549 }
550 }
551
552
553
554
555
556 ret = -ENOMEM;
557 if (flags & MREMAP_MAYMOVE) {
558 unsigned long map_flags = 0;
559 if (vma->vm_flags & VM_MAYSHARE)
560 map_flags |= MAP_SHARED;
561
562 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
563 vma->vm_pgoff +
564 ((addr - vma->vm_start) >> PAGE_SHIFT),
565 map_flags);
566 if (new_addr & ~PAGE_MASK) {
567 ret = new_addr;
568 goto out;
569 }
570
571 ret = move_vma(vma, addr, old_len, new_len, new_addr, &locked);
572 }
573out:
574 if (ret & ~PAGE_MASK)
575 vm_unacct_memory(charged);
576 up_write(¤t->mm->mmap_sem);
577 if (locked && new_len > old_len)
578 mm_populate(new_addr + old_len, new_len - old_len);
579 return ret;
580}
581