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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/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 split_huge_page_pmd(mm, pmd);
45 if (pmd_none_or_clear_bad(pmd))
46 return NULL;
47
48 return pmd;
49}
50
51static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
52 unsigned long addr)
53{
54 pgd_t *pgd;
55 pud_t *pud;
56 pmd_t *pmd;
57
58 pgd = pgd_offset(mm, addr);
59 pud = pud_alloc(mm, pgd, addr);
60 if (!pud)
61 return NULL;
62
63 pmd = pmd_alloc(mm, pud, addr);
64 if (!pmd)
65 return NULL;
66
67 VM_BUG_ON(pmd_trans_huge(*pmd));
68 if (pmd_none(*pmd) && __pte_alloc(mm, vma, pmd, addr))
69 return NULL;
70
71 return pmd;
72}
73
74static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
75 unsigned long old_addr, unsigned long old_end,
76 struct vm_area_struct *new_vma, pmd_t *new_pmd,
77 unsigned long new_addr)
78{
79 struct address_space *mapping = NULL;
80 struct mm_struct *mm = vma->vm_mm;
81 pte_t *old_pte, *new_pte, pte;
82 spinlock_t *old_ptl, *new_ptl;
83 unsigned long old_start;
84
85 old_start = old_addr;
86 mmu_notifier_invalidate_range_start(vma->vm_mm,
87 old_start, old_end);
88 if (vma->vm_file) {
89
90
91
92
93
94
95 mapping = vma->vm_file->f_mapping;
96 spin_lock(&mapping->i_mmap_lock);
97 new_vma->vm_truncate_count = 0;
98 }
99
100
101
102
103
104 old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
105 new_pte = pte_offset_map(new_pmd, new_addr);
106 new_ptl = pte_lockptr(mm, new_pmd);
107 if (new_ptl != old_ptl)
108 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
109 arch_enter_lazy_mmu_mode();
110
111 for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
112 new_pte++, new_addr += PAGE_SIZE) {
113 if (pte_none(*old_pte))
114 continue;
115 pte = ptep_clear_flush(vma, old_addr, old_pte);
116 pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
117 set_pte_at(mm, new_addr, new_pte, pte);
118 }
119
120 arch_leave_lazy_mmu_mode();
121 if (new_ptl != old_ptl)
122 spin_unlock(new_ptl);
123 pte_unmap(new_pte - 1);
124 pte_unmap_unlock(old_pte - 1, old_ptl);
125 if (mapping)
126 spin_unlock(&mapping->i_mmap_lock);
127 mmu_notifier_invalidate_range_end(vma->vm_mm, old_start, old_end);
128}
129
130#define LATENCY_LIMIT (64 * PAGE_SIZE)
131
132unsigned long move_page_tables(struct vm_area_struct *vma,
133 unsigned long old_addr, struct vm_area_struct *new_vma,
134 unsigned long new_addr, unsigned long len)
135{
136 unsigned long extent, next, old_end;
137 pmd_t *old_pmd, *new_pmd;
138
139 old_end = old_addr + len;
140 flush_cache_range(vma, old_addr, old_end);
141
142 for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
143 cond_resched();
144 next = (old_addr + PMD_SIZE) & PMD_MASK;
145 if (next - 1 > old_end)
146 next = old_end;
147 extent = next - old_addr;
148 old_pmd = get_old_pmd(vma->vm_mm, old_addr);
149 if (!old_pmd)
150 continue;
151 new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
152 if (!new_pmd)
153 break;
154 next = (new_addr + PMD_SIZE) & PMD_MASK;
155 if (extent > next - new_addr)
156 extent = next - new_addr;
157 if (extent > LATENCY_LIMIT)
158 extent = LATENCY_LIMIT;
159 move_ptes(vma, old_pmd, old_addr, old_addr + extent,
160 new_vma, new_pmd, new_addr);
161 }
162
163 return len + old_addr - old_end;
164}
165
166static unsigned long move_vma(struct vm_area_struct *vma,
167 unsigned long old_addr, unsigned long old_len,
168 unsigned long new_len, unsigned long new_addr)
169{
170 struct mm_struct *mm = vma->vm_mm;
171 struct vm_area_struct *new_vma;
172 unsigned long vm_flags = vma->vm_flags;
173 unsigned long new_pgoff;
174 unsigned long moved_len;
175 unsigned long excess = 0;
176 unsigned long hiwater_vm;
177 int split = 0;
178 int err;
179
180
181
182
183
184 if (mm->map_count >= sysctl_max_map_count - 3)
185 return -ENOMEM;
186
187
188
189
190
191
192
193
194 err = ksm_madvise(vma, old_addr, old_addr + old_len,
195 MADV_UNMERGEABLE, &vm_flags);
196 if (err)
197 return err;
198
199 new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
200 new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff);
201 if (!new_vma)
202 return -ENOMEM;
203
204 moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len);
205 if (moved_len < old_len) {
206
207
208
209
210
211 move_page_tables(new_vma, new_addr, vma, old_addr, moved_len);
212 vma = new_vma;
213 old_len = new_len;
214 old_addr = new_addr;
215 new_addr = -ENOMEM;
216 }
217
218
219 if (vm_flags & VM_ACCOUNT) {
220 vma->vm_flags &= ~VM_ACCOUNT;
221 excess = vma->vm_end - vma->vm_start - old_len;
222 if (old_addr > vma->vm_start &&
223 old_addr + old_len < vma->vm_end)
224 split = 1;
225 }
226
227
228
229
230
231
232
233
234
235
236 hiwater_vm = mm->hiwater_vm;
237 mm->total_vm += new_len >> PAGE_SHIFT;
238 vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
239
240 if (do_munmap(mm, old_addr, old_len) < 0) {
241
242 vm_unacct_memory(excess >> PAGE_SHIFT);
243 excess = 0;
244 }
245 mm->hiwater_vm = hiwater_vm;
246
247
248 if (excess) {
249 vma->vm_flags |= VM_ACCOUNT;
250 if (split)
251 vma->vm_next->vm_flags |= VM_ACCOUNT;
252 }
253
254 if (vm_flags & VM_LOCKED) {
255 mm->locked_vm += new_len >> PAGE_SHIFT;
256 if (new_len > old_len)
257 mlock_vma_pages_range(new_vma, new_addr + old_len,
258 new_addr + new_len);
259 }
260
261 return new_addr;
262}
263
264static struct vm_area_struct *vma_to_resize(unsigned long addr,
265 unsigned long old_len, unsigned long new_len, unsigned long *p)
266{
267 struct mm_struct *mm = current->mm;
268 struct vm_area_struct *vma = find_vma(mm, addr);
269
270 if (!vma || vma->vm_start > addr)
271 goto Efault;
272
273 if (is_vm_hugetlb_page(vma))
274 goto Einval;
275
276
277 if (old_len > vma->vm_end - addr)
278 goto Efault;
279
280 if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) {
281 if (new_len > old_len)
282 goto Efault;
283 }
284
285 if (vma->vm_flags & VM_LOCKED) {
286 unsigned long locked, lock_limit;
287 locked = mm->locked_vm << PAGE_SHIFT;
288 lock_limit = rlimit(RLIMIT_MEMLOCK);
289 locked += new_len - old_len;
290 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
291 goto Eagain;
292 }
293
294 if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT))
295 goto Enomem;
296
297 if (vma->vm_flags & VM_ACCOUNT) {
298 unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;
299 if (security_vm_enough_memory(charged))
300 goto Efault;
301 *p = charged;
302 }
303
304 return vma;
305
306Efault:
307 return ERR_PTR(-EFAULT);
308Einval:
309 return ERR_PTR(-EINVAL);
310Enomem:
311 return ERR_PTR(-ENOMEM);
312Eagain:
313 return ERR_PTR(-EAGAIN);
314}
315
316static unsigned long mremap_to(unsigned long addr,
317 unsigned long old_len, unsigned long new_addr,
318 unsigned long new_len)
319{
320 struct mm_struct *mm = current->mm;
321 struct vm_area_struct *vma;
322 unsigned long ret = -EINVAL;
323 unsigned long charged = 0;
324 unsigned long map_flags;
325
326 if (new_addr & ~PAGE_MASK)
327 goto out;
328
329 if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
330 goto out;
331
332
333
334
335 if ((new_addr <= addr) && (new_addr+new_len) > addr)
336 goto out;
337
338 if ((addr <= new_addr) && (addr+old_len) > new_addr)
339 goto out;
340
341 ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
342 if (ret)
343 goto out;
344
345 ret = do_munmap(mm, new_addr, new_len);
346 if (ret)
347 goto out;
348
349 if (old_len >= new_len) {
350 ret = do_munmap(mm, addr+new_len, old_len - new_len);
351 if (ret && old_len != new_len)
352 goto out;
353 old_len = new_len;
354 }
355
356 vma = vma_to_resize(addr, old_len, new_len, &charged);
357 if (IS_ERR(vma)) {
358 ret = PTR_ERR(vma);
359 goto out;
360 }
361
362 map_flags = MAP_FIXED;
363 if (vma->vm_flags & VM_MAYSHARE)
364 map_flags |= MAP_SHARED;
365
366 ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
367 ((addr - vma->vm_start) >> PAGE_SHIFT),
368 map_flags);
369 if (ret & ~PAGE_MASK)
370 goto out1;
371
372 ret = move_vma(vma, addr, old_len, new_len, new_addr);
373 if (!(ret & ~PAGE_MASK))
374 goto out;
375out1:
376 vm_unacct_memory(charged);
377
378out:
379 return ret;
380}
381
382static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
383{
384 unsigned long end = vma->vm_end + delta;
385 if (end < vma->vm_end)
386 return 0;
387 if (vma->vm_next && vma->vm_next->vm_start < end)
388 return 0;
389 if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
390 0, MAP_FIXED) & ~PAGE_MASK)
391 return 0;
392 return 1;
393}
394
395
396
397
398
399
400
401
402unsigned long do_mremap(unsigned long addr,
403 unsigned long old_len, unsigned long new_len,
404 unsigned long flags, unsigned long new_addr)
405{
406 struct mm_struct *mm = current->mm;
407 struct vm_area_struct *vma;
408 unsigned long ret = -EINVAL;
409 unsigned long charged = 0;
410
411 if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
412 goto out;
413
414 if (addr & ~PAGE_MASK)
415 goto out;
416
417 old_len = PAGE_ALIGN(old_len);
418 new_len = PAGE_ALIGN(new_len);
419
420
421
422
423
424
425 if (!new_len)
426 goto out;
427
428 if (flags & MREMAP_FIXED) {
429 if (flags & MREMAP_MAYMOVE)
430 ret = mremap_to(addr, old_len, new_addr, new_len);
431 goto out;
432 }
433
434
435
436
437
438
439 if (old_len >= new_len) {
440 ret = do_munmap(mm, addr+new_len, old_len - new_len);
441 if (ret && old_len != new_len)
442 goto out;
443 ret = addr;
444 goto out;
445 }
446
447
448
449
450 vma = vma_to_resize(addr, old_len, new_len, &charged);
451 if (IS_ERR(vma)) {
452 ret = PTR_ERR(vma);
453 goto out;
454 }
455
456
457
458 if (old_len == vma->vm_end - addr) {
459
460 if (vma_expandable(vma, new_len - old_len)) {
461 int pages = (new_len - old_len) >> PAGE_SHIFT;
462
463 if (vma_adjust(vma, vma->vm_start, addr + new_len,
464 vma->vm_pgoff, NULL)) {
465 ret = -ENOMEM;
466 goto out;
467 }
468
469 mm->total_vm += pages;
470 vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
471 if (vma->vm_flags & VM_LOCKED) {
472 mm->locked_vm += pages;
473 mlock_vma_pages_range(vma, addr + old_len,
474 addr + new_len);
475 }
476 ret = addr;
477 goto out;
478 }
479 }
480
481
482
483
484
485 ret = -ENOMEM;
486 if (flags & MREMAP_MAYMOVE) {
487 unsigned long map_flags = 0;
488 if (vma->vm_flags & VM_MAYSHARE)
489 map_flags |= MAP_SHARED;
490
491 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
492 vma->vm_pgoff +
493 ((addr - vma->vm_start) >> PAGE_SHIFT),
494 map_flags);
495 if (new_addr & ~PAGE_MASK) {
496 ret = new_addr;
497 goto out;
498 }
499
500 ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
501 if (ret)
502 goto out;
503 ret = move_vma(vma, addr, old_len, new_len, new_addr);
504 }
505out:
506 if (ret & ~PAGE_MASK)
507 vm_unacct_memory(charged);
508 return ret;
509}
510
511SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
512 unsigned long, new_len, unsigned long, flags,
513 unsigned long, new_addr)
514{
515 unsigned long ret;
516
517 down_write(¤t->mm->mmap_sem);
518 ret = do_mremap(addr, old_len, new_len, flags, new_addr);
519 up_write(¤t->mm->mmap_sem);
520 return ret;
521}
522