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Commit | Line | Data |
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c1a4de99 AA |
1 | /* |
2 | * mm/userfaultfd.c | |
3 | * | |
4 | * Copyright (C) 2015 Red Hat, Inc. | |
5 | * | |
6 | * This work is licensed under the terms of the GNU GPL, version 2. See | |
7 | * the COPYING file in the top-level directory. | |
8 | */ | |
9 | ||
10 | #include <linux/mm.h> | |
174cd4b1 | 11 | #include <linux/sched/signal.h> |
c1a4de99 AA |
12 | #include <linux/pagemap.h> |
13 | #include <linux/rmap.h> | |
14 | #include <linux/swap.h> | |
15 | #include <linux/swapops.h> | |
16 | #include <linux/userfaultfd_k.h> | |
17 | #include <linux/mmu_notifier.h> | |
60d4d2d2 MK |
18 | #include <linux/hugetlb.h> |
19 | #include <linux/pagemap.h> | |
26071ced | 20 | #include <linux/shmem_fs.h> |
c1a4de99 AA |
21 | #include <asm/tlbflush.h> |
22 | #include "internal.h" | |
23 | ||
24 | static int mcopy_atomic_pte(struct mm_struct *dst_mm, | |
25 | pmd_t *dst_pmd, | |
26 | struct vm_area_struct *dst_vma, | |
27 | unsigned long dst_addr, | |
b6ebaedb AA |
28 | unsigned long src_addr, |
29 | struct page **pagep) | |
c1a4de99 AA |
30 | { |
31 | struct mem_cgroup *memcg; | |
32 | pte_t _dst_pte, *dst_pte; | |
33 | spinlock_t *ptl; | |
c1a4de99 AA |
34 | void *page_kaddr; |
35 | int ret; | |
b6ebaedb | 36 | struct page *page; |
fdd65e88 AA |
37 | pgoff_t offset, max_off; |
38 | struct inode *inode; | |
c1a4de99 | 39 | |
b6ebaedb AA |
40 | if (!*pagep) { |
41 | ret = -ENOMEM; | |
42 | page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr); | |
43 | if (!page) | |
44 | goto out; | |
45 | ||
46 | page_kaddr = kmap_atomic(page); | |
47 | ret = copy_from_user(page_kaddr, | |
48 | (const void __user *) src_addr, | |
49 | PAGE_SIZE); | |
50 | kunmap_atomic(page_kaddr); | |
51 | ||
52 | /* fallback to copy_from_user outside mmap_sem */ | |
53 | if (unlikely(ret)) { | |
c9ddac33 | 54 | ret = -ENOENT; |
b6ebaedb AA |
55 | *pagep = page; |
56 | /* don't free the page */ | |
57 | goto out; | |
58 | } | |
59 | } else { | |
60 | page = *pagep; | |
61 | *pagep = NULL; | |
62 | } | |
c1a4de99 AA |
63 | |
64 | /* | |
65 | * The memory barrier inside __SetPageUptodate makes sure that | |
66 | * preceeding stores to the page contents become visible before | |
67 | * the set_pte_at() write. | |
68 | */ | |
69 | __SetPageUptodate(page); | |
70 | ||
71 | ret = -ENOMEM; | |
f627c2f5 | 72 | if (mem_cgroup_try_charge(page, dst_mm, GFP_KERNEL, &memcg, false)) |
c1a4de99 AA |
73 | goto out_release; |
74 | ||
75 | _dst_pte = mk_pte(page, dst_vma->vm_page_prot); | |
76 | if (dst_vma->vm_flags & VM_WRITE) | |
77 | _dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte)); | |
78 | ||
c1a4de99 | 79 | dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); |
fdd65e88 AA |
80 | if (dst_vma->vm_file) { |
81 | /* the shmem MAP_PRIVATE case requires checking the i_size */ | |
82 | inode = dst_vma->vm_file->f_inode; | |
83 | offset = linear_page_index(dst_vma, dst_addr); | |
84 | max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); | |
85 | ret = -EFAULT; | |
86 | if (unlikely(offset >= max_off)) | |
87 | goto out_release_uncharge_unlock; | |
88 | } | |
89 | ret = -EEXIST; | |
c1a4de99 AA |
90 | if (!pte_none(*dst_pte)) |
91 | goto out_release_uncharge_unlock; | |
92 | ||
93 | inc_mm_counter(dst_mm, MM_ANONPAGES); | |
d281ee61 | 94 | page_add_new_anon_rmap(page, dst_vma, dst_addr, false); |
f627c2f5 | 95 | mem_cgroup_commit_charge(page, memcg, false, false); |
c1a4de99 AA |
96 | lru_cache_add_active_or_unevictable(page, dst_vma); |
97 | ||
98 | set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); | |
99 | ||
100 | /* No need to invalidate - it was non-present before */ | |
101 | update_mmu_cache(dst_vma, dst_addr, dst_pte); | |
102 | ||
103 | pte_unmap_unlock(dst_pte, ptl); | |
104 | ret = 0; | |
105 | out: | |
106 | return ret; | |
107 | out_release_uncharge_unlock: | |
108 | pte_unmap_unlock(dst_pte, ptl); | |
f627c2f5 | 109 | mem_cgroup_cancel_charge(page, memcg, false); |
c1a4de99 | 110 | out_release: |
09cbfeaf | 111 | put_page(page); |
c1a4de99 | 112 | goto out; |
c1a4de99 AA |
113 | } |
114 | ||
115 | static int mfill_zeropage_pte(struct mm_struct *dst_mm, | |
116 | pmd_t *dst_pmd, | |
117 | struct vm_area_struct *dst_vma, | |
118 | unsigned long dst_addr) | |
119 | { | |
120 | pte_t _dst_pte, *dst_pte; | |
121 | spinlock_t *ptl; | |
122 | int ret; | |
fdd65e88 AA |
123 | pgoff_t offset, max_off; |
124 | struct inode *inode; | |
c1a4de99 AA |
125 | |
126 | _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), | |
127 | dst_vma->vm_page_prot)); | |
c1a4de99 | 128 | dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); |
fdd65e88 AA |
129 | if (dst_vma->vm_file) { |
130 | /* the shmem MAP_PRIVATE case requires checking the i_size */ | |
131 | inode = dst_vma->vm_file->f_inode; | |
132 | offset = linear_page_index(dst_vma, dst_addr); | |
133 | max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); | |
134 | ret = -EFAULT; | |
135 | if (unlikely(offset >= max_off)) | |
136 | goto out_unlock; | |
137 | } | |
138 | ret = -EEXIST; | |
c1a4de99 AA |
139 | if (!pte_none(*dst_pte)) |
140 | goto out_unlock; | |
141 | set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); | |
142 | /* No need to invalidate - it was non-present before */ | |
143 | update_mmu_cache(dst_vma, dst_addr, dst_pte); | |
144 | ret = 0; | |
145 | out_unlock: | |
146 | pte_unmap_unlock(dst_pte, ptl); | |
147 | return ret; | |
148 | } | |
149 | ||
150 | static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address) | |
151 | { | |
152 | pgd_t *pgd; | |
c2febafc | 153 | p4d_t *p4d; |
c1a4de99 | 154 | pud_t *pud; |
c1a4de99 AA |
155 | |
156 | pgd = pgd_offset(mm, address); | |
c2febafc KS |
157 | p4d = p4d_alloc(mm, pgd, address); |
158 | if (!p4d) | |
159 | return NULL; | |
160 | pud = pud_alloc(mm, p4d, address); | |
161 | if (!pud) | |
162 | return NULL; | |
163 | /* | |
164 | * Note that we didn't run this because the pmd was | |
165 | * missing, the *pmd may be already established and in | |
166 | * turn it may also be a trans_huge_pmd. | |
167 | */ | |
168 | return pmd_alloc(mm, pud, address); | |
c1a4de99 AA |
169 | } |
170 | ||
60d4d2d2 MK |
171 | #ifdef CONFIG_HUGETLB_PAGE |
172 | /* | |
173 | * __mcopy_atomic processing for HUGETLB vmas. Note that this routine is | |
174 | * called with mmap_sem held, it will release mmap_sem before returning. | |
175 | */ | |
176 | static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, | |
177 | struct vm_area_struct *dst_vma, | |
178 | unsigned long dst_start, | |
179 | unsigned long src_start, | |
180 | unsigned long len, | |
181 | bool zeropage) | |
182 | { | |
1c9e8def MK |
183 | int vm_alloc_shared = dst_vma->vm_flags & VM_SHARED; |
184 | int vm_shared = dst_vma->vm_flags & VM_SHARED; | |
60d4d2d2 MK |
185 | ssize_t err; |
186 | pte_t *dst_pte; | |
187 | unsigned long src_addr, dst_addr; | |
188 | long copied; | |
189 | struct page *page; | |
190 | struct hstate *h; | |
191 | unsigned long vma_hpagesize; | |
192 | pgoff_t idx; | |
193 | u32 hash; | |
194 | struct address_space *mapping; | |
195 | ||
196 | /* | |
197 | * There is no default zero huge page for all huge page sizes as | |
198 | * supported by hugetlb. A PMD_SIZE huge pages may exist as used | |
199 | * by THP. Since we can not reliably insert a zero page, this | |
200 | * feature is not supported. | |
201 | */ | |
202 | if (zeropage) { | |
203 | up_read(&dst_mm->mmap_sem); | |
204 | return -EINVAL; | |
205 | } | |
206 | ||
207 | src_addr = src_start; | |
208 | dst_addr = dst_start; | |
209 | copied = 0; | |
210 | page = NULL; | |
211 | vma_hpagesize = vma_kernel_pagesize(dst_vma); | |
212 | ||
213 | /* | |
214 | * Validate alignment based on huge page size | |
215 | */ | |
216 | err = -EINVAL; | |
217 | if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1)) | |
218 | goto out_unlock; | |
219 | ||
220 | retry: | |
221 | /* | |
222 | * On routine entry dst_vma is set. If we had to drop mmap_sem and | |
223 | * retry, dst_vma will be set to NULL and we must lookup again. | |
224 | */ | |
225 | if (!dst_vma) { | |
27d02568 | 226 | err = -ENOENT; |
60d4d2d2 MK |
227 | dst_vma = find_vma(dst_mm, dst_start); |
228 | if (!dst_vma || !is_vm_hugetlb_page(dst_vma)) | |
229 | goto out_unlock; | |
60d4d2d2 | 230 | /* |
613c12df AA |
231 | * Check the vma is registered in uffd, this is |
232 | * required to enforce the VM_MAYWRITE check done at | |
233 | * uffd registration time. | |
60d4d2d2 | 234 | */ |
27d02568 MR |
235 | if (!dst_vma->vm_userfaultfd_ctx.ctx) |
236 | goto out_unlock; | |
237 | ||
60d4d2d2 MK |
238 | if (dst_start < dst_vma->vm_start || |
239 | dst_start + len > dst_vma->vm_end) | |
240 | goto out_unlock; | |
1c9e8def | 241 | |
27d02568 MR |
242 | err = -EINVAL; |
243 | if (vma_hpagesize != vma_kernel_pagesize(dst_vma)) | |
244 | goto out_unlock; | |
245 | ||
1c9e8def | 246 | vm_shared = dst_vma->vm_flags & VM_SHARED; |
60d4d2d2 MK |
247 | } |
248 | ||
249 | if (WARN_ON(dst_addr & (vma_hpagesize - 1) || | |
250 | (len - copied) & (vma_hpagesize - 1))) | |
251 | goto out_unlock; | |
252 | ||
60d4d2d2 | 253 | /* |
1c9e8def | 254 | * If not shared, ensure the dst_vma has a anon_vma. |
60d4d2d2 MK |
255 | */ |
256 | err = -ENOMEM; | |
1c9e8def MK |
257 | if (!vm_shared) { |
258 | if (unlikely(anon_vma_prepare(dst_vma))) | |
259 | goto out_unlock; | |
260 | } | |
60d4d2d2 MK |
261 | |
262 | h = hstate_vma(dst_vma); | |
263 | ||
264 | while (src_addr < src_start + len) { | |
265 | pte_t dst_pteval; | |
266 | ||
267 | BUG_ON(dst_addr >= dst_start + len); | |
268 | VM_BUG_ON(dst_addr & ~huge_page_mask(h)); | |
269 | ||
270 | /* | |
271 | * Serialize via hugetlb_fault_mutex | |
272 | */ | |
273 | idx = linear_page_index(dst_vma, dst_addr); | |
274 | mapping = dst_vma->vm_file->f_mapping; | |
0e8e2dc8 | 275 | hash = hugetlb_fault_mutex_hash(h, mapping, idx, dst_addr); |
60d4d2d2 MK |
276 | mutex_lock(&hugetlb_fault_mutex_table[hash]); |
277 | ||
278 | err = -ENOMEM; | |
279 | dst_pte = huge_pte_alloc(dst_mm, dst_addr, huge_page_size(h)); | |
280 | if (!dst_pte) { | |
281 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); | |
282 | goto out_unlock; | |
283 | } | |
284 | ||
285 | err = -EEXIST; | |
286 | dst_pteval = huge_ptep_get(dst_pte); | |
287 | if (!huge_pte_none(dst_pteval)) { | |
288 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); | |
289 | goto out_unlock; | |
290 | } | |
291 | ||
292 | err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, | |
293 | dst_addr, src_addr, &page); | |
294 | ||
295 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); | |
1c9e8def | 296 | vm_alloc_shared = vm_shared; |
60d4d2d2 MK |
297 | |
298 | cond_resched(); | |
299 | ||
c9ddac33 | 300 | if (unlikely(err == -ENOENT)) { |
60d4d2d2 MK |
301 | up_read(&dst_mm->mmap_sem); |
302 | BUG_ON(!page); | |
303 | ||
304 | err = copy_huge_page_from_user(page, | |
305 | (const void __user *)src_addr, | |
810a56b9 | 306 | pages_per_huge_page(h), true); |
60d4d2d2 MK |
307 | if (unlikely(err)) { |
308 | err = -EFAULT; | |
309 | goto out; | |
310 | } | |
311 | down_read(&dst_mm->mmap_sem); | |
312 | ||
313 | dst_vma = NULL; | |
314 | goto retry; | |
315 | } else | |
316 | BUG_ON(page); | |
317 | ||
318 | if (!err) { | |
319 | dst_addr += vma_hpagesize; | |
320 | src_addr += vma_hpagesize; | |
321 | copied += vma_hpagesize; | |
322 | ||
323 | if (fatal_signal_pending(current)) | |
324 | err = -EINTR; | |
325 | } | |
326 | if (err) | |
327 | break; | |
328 | } | |
329 | ||
330 | out_unlock: | |
331 | up_read(&dst_mm->mmap_sem); | |
332 | out: | |
21205bf8 MK |
333 | if (page) { |
334 | /* | |
335 | * We encountered an error and are about to free a newly | |
1c9e8def MK |
336 | * allocated huge page. |
337 | * | |
338 | * Reservation handling is very subtle, and is different for | |
339 | * private and shared mappings. See the routine | |
340 | * restore_reserve_on_error for details. Unfortunately, we | |
341 | * can not call restore_reserve_on_error now as it would | |
342 | * require holding mmap_sem. | |
343 | * | |
344 | * If a reservation for the page existed in the reservation | |
345 | * map of a private mapping, the map was modified to indicate | |
346 | * the reservation was consumed when the page was allocated. | |
347 | * We clear the PagePrivate flag now so that the global | |
21205bf8 MK |
348 | * reserve count will not be incremented in free_huge_page. |
349 | * The reservation map will still indicate the reservation | |
350 | * was consumed and possibly prevent later page allocation. | |
1c9e8def MK |
351 | * This is better than leaking a global reservation. If no |
352 | * reservation existed, it is still safe to clear PagePrivate | |
353 | * as no adjustments to reservation counts were made during | |
354 | * allocation. | |
355 | * | |
356 | * The reservation map for shared mappings indicates which | |
357 | * pages have reservations. When a huge page is allocated | |
358 | * for an address with a reservation, no change is made to | |
359 | * the reserve map. In this case PagePrivate will be set | |
360 | * to indicate that the global reservation count should be | |
361 | * incremented when the page is freed. This is the desired | |
362 | * behavior. However, when a huge page is allocated for an | |
363 | * address without a reservation a reservation entry is added | |
364 | * to the reservation map, and PagePrivate will not be set. | |
365 | * When the page is freed, the global reserve count will NOT | |
366 | * be incremented and it will appear as though we have leaked | |
367 | * reserved page. In this case, set PagePrivate so that the | |
368 | * global reserve count will be incremented to match the | |
369 | * reservation map entry which was created. | |
370 | * | |
371 | * Note that vm_alloc_shared is based on the flags of the vma | |
372 | * for which the page was originally allocated. dst_vma could | |
373 | * be different or NULL on error. | |
21205bf8 | 374 | */ |
1c9e8def MK |
375 | if (vm_alloc_shared) |
376 | SetPagePrivate(page); | |
377 | else | |
378 | ClearPagePrivate(page); | |
60d4d2d2 | 379 | put_page(page); |
21205bf8 | 380 | } |
60d4d2d2 MK |
381 | BUG_ON(copied < 0); |
382 | BUG_ON(err > 0); | |
383 | BUG_ON(!copied && !err); | |
384 | return copied ? copied : err; | |
385 | } | |
386 | #else /* !CONFIG_HUGETLB_PAGE */ | |
387 | /* fail at build time if gcc attempts to use this */ | |
388 | extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, | |
389 | struct vm_area_struct *dst_vma, | |
390 | unsigned long dst_start, | |
391 | unsigned long src_start, | |
392 | unsigned long len, | |
393 | bool zeropage); | |
394 | #endif /* CONFIG_HUGETLB_PAGE */ | |
395 | ||
3217d3c7 MR |
396 | static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, |
397 | pmd_t *dst_pmd, | |
398 | struct vm_area_struct *dst_vma, | |
399 | unsigned long dst_addr, | |
400 | unsigned long src_addr, | |
401 | struct page **page, | |
402 | bool zeropage) | |
403 | { | |
404 | ssize_t err; | |
405 | ||
ea261174 AA |
406 | /* |
407 | * The normal page fault path for a shmem will invoke the | |
408 | * fault, fill the hole in the file and COW it right away. The | |
409 | * result generates plain anonymous memory. So when we are | |
410 | * asked to fill an hole in a MAP_PRIVATE shmem mapping, we'll | |
411 | * generate anonymous memory directly without actually filling | |
412 | * the hole. For the MAP_PRIVATE case the robustness check | |
413 | * only happens in the pagetable (to verify it's still none) | |
414 | * and not in the radix tree. | |
415 | */ | |
416 | if (!(dst_vma->vm_flags & VM_SHARED)) { | |
3217d3c7 MR |
417 | if (!zeropage) |
418 | err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, | |
419 | dst_addr, src_addr, page); | |
420 | else | |
421 | err = mfill_zeropage_pte(dst_mm, dst_pmd, | |
422 | dst_vma, dst_addr); | |
423 | } else { | |
8fb44e54 | 424 | if (!zeropage) |
3217d3c7 MR |
425 | err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd, |
426 | dst_vma, dst_addr, | |
427 | src_addr, page); | |
8fb44e54 MR |
428 | else |
429 | err = shmem_mfill_zeropage_pte(dst_mm, dst_pmd, | |
430 | dst_vma, dst_addr); | |
3217d3c7 MR |
431 | } |
432 | ||
433 | return err; | |
434 | } | |
435 | ||
c1a4de99 AA |
436 | static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, |
437 | unsigned long dst_start, | |
438 | unsigned long src_start, | |
439 | unsigned long len, | |
440 | bool zeropage) | |
441 | { | |
442 | struct vm_area_struct *dst_vma; | |
443 | ssize_t err; | |
444 | pmd_t *dst_pmd; | |
445 | unsigned long src_addr, dst_addr; | |
b6ebaedb AA |
446 | long copied; |
447 | struct page *page; | |
c1a4de99 AA |
448 | |
449 | /* | |
450 | * Sanitize the command parameters: | |
451 | */ | |
452 | BUG_ON(dst_start & ~PAGE_MASK); | |
453 | BUG_ON(len & ~PAGE_MASK); | |
454 | ||
455 | /* Does the address range wrap, or is the span zero-sized? */ | |
456 | BUG_ON(src_start + len <= src_start); | |
457 | BUG_ON(dst_start + len <= dst_start); | |
458 | ||
b6ebaedb AA |
459 | src_addr = src_start; |
460 | dst_addr = dst_start; | |
461 | copied = 0; | |
462 | page = NULL; | |
463 | retry: | |
c1a4de99 AA |
464 | down_read(&dst_mm->mmap_sem); |
465 | ||
466 | /* | |
467 | * Make sure the vma is not shared, that the dst range is | |
468 | * both valid and fully within a single existing vma. | |
469 | */ | |
27d02568 | 470 | err = -ENOENT; |
c1a4de99 | 471 | dst_vma = find_vma(dst_mm, dst_start); |
26071ced MR |
472 | if (!dst_vma) |
473 | goto out_unlock; | |
1c9e8def | 474 | /* |
613c12df AA |
475 | * Check the vma is registered in uffd, this is required to |
476 | * enforce the VM_MAYWRITE check done at uffd registration | |
477 | * time. | |
1c9e8def | 478 | */ |
27d02568 | 479 | if (!dst_vma->vm_userfaultfd_ctx.ctx) |
b6ebaedb | 480 | goto out_unlock; |
1c9e8def | 481 | |
c1a4de99 AA |
482 | if (dst_start < dst_vma->vm_start || |
483 | dst_start + len > dst_vma->vm_end) | |
b6ebaedb | 484 | goto out_unlock; |
c1a4de99 | 485 | |
27d02568 MR |
486 | err = -EINVAL; |
487 | /* | |
488 | * shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but | |
489 | * it will overwrite vm_ops, so vma_is_anonymous must return false. | |
490 | */ | |
491 | if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) && | |
492 | dst_vma->vm_flags & VM_SHARED)) | |
493 | goto out_unlock; | |
494 | ||
60d4d2d2 MK |
495 | /* |
496 | * If this is a HUGETLB vma, pass off to appropriate routine | |
497 | */ | |
498 | if (is_vm_hugetlb_page(dst_vma)) | |
499 | return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start, | |
500 | src_start, len, zeropage); | |
501 | ||
26071ced | 502 | if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) |
b6ebaedb | 503 | goto out_unlock; |
c1a4de99 AA |
504 | |
505 | /* | |
506 | * Ensure the dst_vma has a anon_vma or this page | |
507 | * would get a NULL anon_vma when moved in the | |
508 | * dst_vma. | |
509 | */ | |
510 | err = -ENOMEM; | |
ea261174 AA |
511 | if (!(dst_vma->vm_flags & VM_SHARED) && |
512 | unlikely(anon_vma_prepare(dst_vma))) | |
b6ebaedb | 513 | goto out_unlock; |
c1a4de99 | 514 | |
b6ebaedb | 515 | while (src_addr < src_start + len) { |
c1a4de99 | 516 | pmd_t dst_pmdval; |
b6ebaedb | 517 | |
c1a4de99 | 518 | BUG_ON(dst_addr >= dst_start + len); |
b6ebaedb | 519 | |
c1a4de99 AA |
520 | dst_pmd = mm_alloc_pmd(dst_mm, dst_addr); |
521 | if (unlikely(!dst_pmd)) { | |
522 | err = -ENOMEM; | |
523 | break; | |
524 | } | |
525 | ||
526 | dst_pmdval = pmd_read_atomic(dst_pmd); | |
527 | /* | |
528 | * If the dst_pmd is mapped as THP don't | |
529 | * override it and just be strict. | |
530 | */ | |
531 | if (unlikely(pmd_trans_huge(dst_pmdval))) { | |
532 | err = -EEXIST; | |
533 | break; | |
534 | } | |
535 | if (unlikely(pmd_none(dst_pmdval)) && | |
3ed3a4f0 | 536 | unlikely(__pte_alloc(dst_mm, dst_pmd, dst_addr))) { |
c1a4de99 AA |
537 | err = -ENOMEM; |
538 | break; | |
539 | } | |
540 | /* If an huge pmd materialized from under us fail */ | |
541 | if (unlikely(pmd_trans_huge(*dst_pmd))) { | |
542 | err = -EFAULT; | |
543 | break; | |
544 | } | |
545 | ||
546 | BUG_ON(pmd_none(*dst_pmd)); | |
547 | BUG_ON(pmd_trans_huge(*dst_pmd)); | |
548 | ||
3217d3c7 MR |
549 | err = mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, |
550 | src_addr, &page, zeropage); | |
c1a4de99 AA |
551 | cond_resched(); |
552 | ||
c9ddac33 | 553 | if (unlikely(err == -ENOENT)) { |
b6ebaedb AA |
554 | void *page_kaddr; |
555 | ||
556 | up_read(&dst_mm->mmap_sem); | |
557 | BUG_ON(!page); | |
558 | ||
559 | page_kaddr = kmap(page); | |
560 | err = copy_from_user(page_kaddr, | |
561 | (const void __user *) src_addr, | |
562 | PAGE_SIZE); | |
563 | kunmap(page); | |
564 | if (unlikely(err)) { | |
565 | err = -EFAULT; | |
566 | goto out; | |
567 | } | |
568 | goto retry; | |
569 | } else | |
570 | BUG_ON(page); | |
571 | ||
c1a4de99 AA |
572 | if (!err) { |
573 | dst_addr += PAGE_SIZE; | |
574 | src_addr += PAGE_SIZE; | |
575 | copied += PAGE_SIZE; | |
576 | ||
577 | if (fatal_signal_pending(current)) | |
578 | err = -EINTR; | |
579 | } | |
580 | if (err) | |
581 | break; | |
582 | } | |
583 | ||
b6ebaedb | 584 | out_unlock: |
c1a4de99 | 585 | up_read(&dst_mm->mmap_sem); |
b6ebaedb AA |
586 | out: |
587 | if (page) | |
09cbfeaf | 588 | put_page(page); |
c1a4de99 AA |
589 | BUG_ON(copied < 0); |
590 | BUG_ON(err > 0); | |
591 | BUG_ON(!copied && !err); | |
592 | return copied ? copied : err; | |
593 | } | |
594 | ||
595 | ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, | |
596 | unsigned long src_start, unsigned long len) | |
597 | { | |
598 | return __mcopy_atomic(dst_mm, dst_start, src_start, len, false); | |
599 | } | |
600 | ||
601 | ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start, | |
602 | unsigned long len) | |
603 | { | |
604 | return __mcopy_atomic(dst_mm, start, 0, len, true); | |
605 | } |