]>
Commit | Line | Data |
---|---|---|
20c8ccb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
c1a4de99 AA |
2 | /* |
3 | * mm/userfaultfd.c | |
4 | * | |
5 | * Copyright (C) 2015 Red Hat, Inc. | |
c1a4de99 AA |
6 | */ |
7 | ||
8 | #include <linux/mm.h> | |
174cd4b1 | 9 | #include <linux/sched/signal.h> |
c1a4de99 AA |
10 | #include <linux/pagemap.h> |
11 | #include <linux/rmap.h> | |
12 | #include <linux/swap.h> | |
13 | #include <linux/swapops.h> | |
14 | #include <linux/userfaultfd_k.h> | |
15 | #include <linux/mmu_notifier.h> | |
60d4d2d2 | 16 | #include <linux/hugetlb.h> |
26071ced | 17 | #include <linux/shmem_fs.h> |
c1a4de99 AA |
18 | #include <asm/tlbflush.h> |
19 | #include "internal.h" | |
20 | ||
643aa36e WY |
21 | static __always_inline |
22 | struct vm_area_struct *find_dst_vma(struct mm_struct *dst_mm, | |
23 | unsigned long dst_start, | |
24 | unsigned long len) | |
25 | { | |
26 | /* | |
27 | * Make sure that the dst range is both valid and fully within a | |
28 | * single existing vma. | |
29 | */ | |
30 | struct vm_area_struct *dst_vma; | |
31 | ||
32 | dst_vma = find_vma(dst_mm, dst_start); | |
33 | if (!dst_vma) | |
34 | return NULL; | |
35 | ||
36 | if (dst_start < dst_vma->vm_start || | |
37 | dst_start + len > dst_vma->vm_end) | |
38 | return NULL; | |
39 | ||
40 | /* | |
41 | * Check the vma is registered in uffd, this is required to | |
42 | * enforce the VM_MAYWRITE check done at uffd registration | |
43 | * time. | |
44 | */ | |
45 | if (!dst_vma->vm_userfaultfd_ctx.ctx) | |
46 | return NULL; | |
47 | ||
48 | return dst_vma; | |
49 | } | |
50 | ||
c1a4de99 AA |
51 | static int mcopy_atomic_pte(struct mm_struct *dst_mm, |
52 | pmd_t *dst_pmd, | |
53 | struct vm_area_struct *dst_vma, | |
54 | unsigned long dst_addr, | |
b6ebaedb | 55 | unsigned long src_addr, |
72981e0e AA |
56 | struct page **pagep, |
57 | bool wp_copy) | |
c1a4de99 AA |
58 | { |
59 | struct mem_cgroup *memcg; | |
60 | pte_t _dst_pte, *dst_pte; | |
61 | spinlock_t *ptl; | |
c1a4de99 AA |
62 | void *page_kaddr; |
63 | int ret; | |
b6ebaedb | 64 | struct page *page; |
e2a50c1f AA |
65 | pgoff_t offset, max_off; |
66 | struct inode *inode; | |
c1a4de99 | 67 | |
b6ebaedb AA |
68 | if (!*pagep) { |
69 | ret = -ENOMEM; | |
70 | page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr); | |
71 | if (!page) | |
72 | goto out; | |
73 | ||
74 | page_kaddr = kmap_atomic(page); | |
75 | ret = copy_from_user(page_kaddr, | |
76 | (const void __user *) src_addr, | |
77 | PAGE_SIZE); | |
78 | kunmap_atomic(page_kaddr); | |
79 | ||
80 | /* fallback to copy_from_user outside mmap_sem */ | |
81 | if (unlikely(ret)) { | |
9e368259 | 82 | ret = -ENOENT; |
b6ebaedb AA |
83 | *pagep = page; |
84 | /* don't free the page */ | |
85 | goto out; | |
86 | } | |
87 | } else { | |
88 | page = *pagep; | |
89 | *pagep = NULL; | |
90 | } | |
c1a4de99 AA |
91 | |
92 | /* | |
93 | * The memory barrier inside __SetPageUptodate makes sure that | |
f4f5329d | 94 | * preceding stores to the page contents become visible before |
c1a4de99 AA |
95 | * the set_pte_at() write. |
96 | */ | |
97 | __SetPageUptodate(page); | |
98 | ||
99 | ret = -ENOMEM; | |
f627c2f5 | 100 | if (mem_cgroup_try_charge(page, dst_mm, GFP_KERNEL, &memcg, false)) |
c1a4de99 AA |
101 | goto out_release; |
102 | ||
72981e0e | 103 | _dst_pte = pte_mkdirty(mk_pte(page, dst_vma->vm_page_prot)); |
292924b2 PX |
104 | if (dst_vma->vm_flags & VM_WRITE) { |
105 | if (wp_copy) | |
106 | _dst_pte = pte_mkuffd_wp(_dst_pte); | |
107 | else | |
108 | _dst_pte = pte_mkwrite(_dst_pte); | |
109 | } | |
c1a4de99 | 110 | |
c1a4de99 | 111 | dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); |
e2a50c1f AA |
112 | if (dst_vma->vm_file) { |
113 | /* the shmem MAP_PRIVATE case requires checking the i_size */ | |
114 | inode = dst_vma->vm_file->f_inode; | |
115 | offset = linear_page_index(dst_vma, dst_addr); | |
116 | max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); | |
117 | ret = -EFAULT; | |
118 | if (unlikely(offset >= max_off)) | |
119 | goto out_release_uncharge_unlock; | |
120 | } | |
121 | ret = -EEXIST; | |
c1a4de99 AA |
122 | if (!pte_none(*dst_pte)) |
123 | goto out_release_uncharge_unlock; | |
124 | ||
125 | inc_mm_counter(dst_mm, MM_ANONPAGES); | |
d281ee61 | 126 | page_add_new_anon_rmap(page, dst_vma, dst_addr, false); |
f627c2f5 | 127 | mem_cgroup_commit_charge(page, memcg, false, false); |
c1a4de99 AA |
128 | lru_cache_add_active_or_unevictable(page, dst_vma); |
129 | ||
130 | set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); | |
131 | ||
132 | /* No need to invalidate - it was non-present before */ | |
133 | update_mmu_cache(dst_vma, dst_addr, dst_pte); | |
134 | ||
135 | pte_unmap_unlock(dst_pte, ptl); | |
136 | ret = 0; | |
137 | out: | |
138 | return ret; | |
139 | out_release_uncharge_unlock: | |
140 | pte_unmap_unlock(dst_pte, ptl); | |
f627c2f5 | 141 | mem_cgroup_cancel_charge(page, memcg, false); |
c1a4de99 | 142 | out_release: |
09cbfeaf | 143 | put_page(page); |
c1a4de99 | 144 | goto out; |
c1a4de99 AA |
145 | } |
146 | ||
147 | static int mfill_zeropage_pte(struct mm_struct *dst_mm, | |
148 | pmd_t *dst_pmd, | |
149 | struct vm_area_struct *dst_vma, | |
150 | unsigned long dst_addr) | |
151 | { | |
152 | pte_t _dst_pte, *dst_pte; | |
153 | spinlock_t *ptl; | |
154 | int ret; | |
e2a50c1f AA |
155 | pgoff_t offset, max_off; |
156 | struct inode *inode; | |
c1a4de99 AA |
157 | |
158 | _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), | |
159 | dst_vma->vm_page_prot)); | |
c1a4de99 | 160 | dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); |
e2a50c1f AA |
161 | if (dst_vma->vm_file) { |
162 | /* the shmem MAP_PRIVATE case requires checking the i_size */ | |
163 | inode = dst_vma->vm_file->f_inode; | |
164 | offset = linear_page_index(dst_vma, dst_addr); | |
165 | max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); | |
166 | ret = -EFAULT; | |
167 | if (unlikely(offset >= max_off)) | |
168 | goto out_unlock; | |
169 | } | |
170 | ret = -EEXIST; | |
c1a4de99 AA |
171 | if (!pte_none(*dst_pte)) |
172 | goto out_unlock; | |
173 | set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); | |
174 | /* No need to invalidate - it was non-present before */ | |
175 | update_mmu_cache(dst_vma, dst_addr, dst_pte); | |
176 | ret = 0; | |
177 | out_unlock: | |
178 | pte_unmap_unlock(dst_pte, ptl); | |
179 | return ret; | |
180 | } | |
181 | ||
182 | static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address) | |
183 | { | |
184 | pgd_t *pgd; | |
c2febafc | 185 | p4d_t *p4d; |
c1a4de99 | 186 | pud_t *pud; |
c1a4de99 AA |
187 | |
188 | pgd = pgd_offset(mm, address); | |
c2febafc KS |
189 | p4d = p4d_alloc(mm, pgd, address); |
190 | if (!p4d) | |
191 | return NULL; | |
192 | pud = pud_alloc(mm, p4d, address); | |
193 | if (!pud) | |
194 | return NULL; | |
195 | /* | |
196 | * Note that we didn't run this because the pmd was | |
197 | * missing, the *pmd may be already established and in | |
198 | * turn it may also be a trans_huge_pmd. | |
199 | */ | |
200 | return pmd_alloc(mm, pud, address); | |
c1a4de99 AA |
201 | } |
202 | ||
60d4d2d2 MK |
203 | #ifdef CONFIG_HUGETLB_PAGE |
204 | /* | |
205 | * __mcopy_atomic processing for HUGETLB vmas. Note that this routine is | |
206 | * called with mmap_sem held, it will release mmap_sem before returning. | |
207 | */ | |
208 | static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, | |
209 | struct vm_area_struct *dst_vma, | |
210 | unsigned long dst_start, | |
211 | unsigned long src_start, | |
212 | unsigned long len, | |
213 | bool zeropage) | |
214 | { | |
1c9e8def MK |
215 | int vm_alloc_shared = dst_vma->vm_flags & VM_SHARED; |
216 | int vm_shared = dst_vma->vm_flags & VM_SHARED; | |
60d4d2d2 MK |
217 | ssize_t err; |
218 | pte_t *dst_pte; | |
219 | unsigned long src_addr, dst_addr; | |
220 | long copied; | |
221 | struct page *page; | |
60d4d2d2 MK |
222 | unsigned long vma_hpagesize; |
223 | pgoff_t idx; | |
224 | u32 hash; | |
225 | struct address_space *mapping; | |
226 | ||
227 | /* | |
228 | * There is no default zero huge page for all huge page sizes as | |
229 | * supported by hugetlb. A PMD_SIZE huge pages may exist as used | |
230 | * by THP. Since we can not reliably insert a zero page, this | |
231 | * feature is not supported. | |
232 | */ | |
233 | if (zeropage) { | |
234 | up_read(&dst_mm->mmap_sem); | |
235 | return -EINVAL; | |
236 | } | |
237 | ||
238 | src_addr = src_start; | |
239 | dst_addr = dst_start; | |
240 | copied = 0; | |
241 | page = NULL; | |
242 | vma_hpagesize = vma_kernel_pagesize(dst_vma); | |
243 | ||
244 | /* | |
245 | * Validate alignment based on huge page size | |
246 | */ | |
247 | err = -EINVAL; | |
248 | if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1)) | |
249 | goto out_unlock; | |
250 | ||
251 | retry: | |
252 | /* | |
253 | * On routine entry dst_vma is set. If we had to drop mmap_sem and | |
254 | * retry, dst_vma will be set to NULL and we must lookup again. | |
255 | */ | |
256 | if (!dst_vma) { | |
27d02568 | 257 | err = -ENOENT; |
643aa36e | 258 | dst_vma = find_dst_vma(dst_mm, dst_start, len); |
60d4d2d2 MK |
259 | if (!dst_vma || !is_vm_hugetlb_page(dst_vma)) |
260 | goto out_unlock; | |
1c9e8def | 261 | |
27d02568 MR |
262 | err = -EINVAL; |
263 | if (vma_hpagesize != vma_kernel_pagesize(dst_vma)) | |
264 | goto out_unlock; | |
265 | ||
1c9e8def | 266 | vm_shared = dst_vma->vm_flags & VM_SHARED; |
60d4d2d2 MK |
267 | } |
268 | ||
60d4d2d2 | 269 | /* |
1c9e8def | 270 | * If not shared, ensure the dst_vma has a anon_vma. |
60d4d2d2 MK |
271 | */ |
272 | err = -ENOMEM; | |
1c9e8def MK |
273 | if (!vm_shared) { |
274 | if (unlikely(anon_vma_prepare(dst_vma))) | |
275 | goto out_unlock; | |
276 | } | |
60d4d2d2 | 277 | |
60d4d2d2 MK |
278 | while (src_addr < src_start + len) { |
279 | pte_t dst_pteval; | |
280 | ||
281 | BUG_ON(dst_addr >= dst_start + len); | |
60d4d2d2 MK |
282 | |
283 | /* | |
c0d0381a MK |
284 | * Serialize via i_mmap_rwsem and hugetlb_fault_mutex. |
285 | * i_mmap_rwsem ensures the dst_pte remains valid even | |
286 | * in the case of shared pmds. fault mutex prevents | |
287 | * races with other faulting threads. | |
60d4d2d2 | 288 | */ |
ddeaab32 | 289 | mapping = dst_vma->vm_file->f_mapping; |
c0d0381a MK |
290 | i_mmap_lock_read(mapping); |
291 | idx = linear_page_index(dst_vma, dst_addr); | |
188b04a7 | 292 | hash = hugetlb_fault_mutex_hash(mapping, idx); |
60d4d2d2 MK |
293 | mutex_lock(&hugetlb_fault_mutex_table[hash]); |
294 | ||
295 | err = -ENOMEM; | |
4fb07ee6 | 296 | dst_pte = huge_pte_alloc(dst_mm, dst_addr, vma_hpagesize); |
60d4d2d2 MK |
297 | if (!dst_pte) { |
298 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); | |
c0d0381a | 299 | i_mmap_unlock_read(mapping); |
60d4d2d2 MK |
300 | goto out_unlock; |
301 | } | |
302 | ||
303 | err = -EEXIST; | |
304 | dst_pteval = huge_ptep_get(dst_pte); | |
305 | if (!huge_pte_none(dst_pteval)) { | |
306 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); | |
c0d0381a | 307 | i_mmap_unlock_read(mapping); |
60d4d2d2 MK |
308 | goto out_unlock; |
309 | } | |
310 | ||
311 | err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, | |
312 | dst_addr, src_addr, &page); | |
313 | ||
314 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); | |
c0d0381a | 315 | i_mmap_unlock_read(mapping); |
1c9e8def | 316 | vm_alloc_shared = vm_shared; |
60d4d2d2 MK |
317 | |
318 | cond_resched(); | |
319 | ||
9e368259 | 320 | if (unlikely(err == -ENOENT)) { |
60d4d2d2 MK |
321 | up_read(&dst_mm->mmap_sem); |
322 | BUG_ON(!page); | |
323 | ||
324 | err = copy_huge_page_from_user(page, | |
325 | (const void __user *)src_addr, | |
4fb07ee6 WY |
326 | vma_hpagesize / PAGE_SIZE, |
327 | true); | |
60d4d2d2 MK |
328 | if (unlikely(err)) { |
329 | err = -EFAULT; | |
330 | goto out; | |
331 | } | |
332 | down_read(&dst_mm->mmap_sem); | |
333 | ||
334 | dst_vma = NULL; | |
335 | goto retry; | |
336 | } else | |
337 | BUG_ON(page); | |
338 | ||
339 | if (!err) { | |
340 | dst_addr += vma_hpagesize; | |
341 | src_addr += vma_hpagesize; | |
342 | copied += vma_hpagesize; | |
343 | ||
344 | if (fatal_signal_pending(current)) | |
345 | err = -EINTR; | |
346 | } | |
347 | if (err) | |
348 | break; | |
349 | } | |
350 | ||
351 | out_unlock: | |
352 | up_read(&dst_mm->mmap_sem); | |
353 | out: | |
21205bf8 MK |
354 | if (page) { |
355 | /* | |
356 | * We encountered an error and are about to free a newly | |
1c9e8def MK |
357 | * allocated huge page. |
358 | * | |
359 | * Reservation handling is very subtle, and is different for | |
360 | * private and shared mappings. See the routine | |
361 | * restore_reserve_on_error for details. Unfortunately, we | |
362 | * can not call restore_reserve_on_error now as it would | |
363 | * require holding mmap_sem. | |
364 | * | |
365 | * If a reservation for the page existed in the reservation | |
366 | * map of a private mapping, the map was modified to indicate | |
367 | * the reservation was consumed when the page was allocated. | |
368 | * We clear the PagePrivate flag now so that the global | |
21205bf8 MK |
369 | * reserve count will not be incremented in free_huge_page. |
370 | * The reservation map will still indicate the reservation | |
371 | * was consumed and possibly prevent later page allocation. | |
1c9e8def MK |
372 | * This is better than leaking a global reservation. If no |
373 | * reservation existed, it is still safe to clear PagePrivate | |
374 | * as no adjustments to reservation counts were made during | |
375 | * allocation. | |
376 | * | |
377 | * The reservation map for shared mappings indicates which | |
378 | * pages have reservations. When a huge page is allocated | |
379 | * for an address with a reservation, no change is made to | |
380 | * the reserve map. In this case PagePrivate will be set | |
381 | * to indicate that the global reservation count should be | |
382 | * incremented when the page is freed. This is the desired | |
383 | * behavior. However, when a huge page is allocated for an | |
384 | * address without a reservation a reservation entry is added | |
385 | * to the reservation map, and PagePrivate will not be set. | |
386 | * When the page is freed, the global reserve count will NOT | |
387 | * be incremented and it will appear as though we have leaked | |
388 | * reserved page. In this case, set PagePrivate so that the | |
389 | * global reserve count will be incremented to match the | |
390 | * reservation map entry which was created. | |
391 | * | |
392 | * Note that vm_alloc_shared is based on the flags of the vma | |
393 | * for which the page was originally allocated. dst_vma could | |
394 | * be different or NULL on error. | |
21205bf8 | 395 | */ |
1c9e8def MK |
396 | if (vm_alloc_shared) |
397 | SetPagePrivate(page); | |
398 | else | |
399 | ClearPagePrivate(page); | |
60d4d2d2 | 400 | put_page(page); |
21205bf8 | 401 | } |
60d4d2d2 MK |
402 | BUG_ON(copied < 0); |
403 | BUG_ON(err > 0); | |
404 | BUG_ON(!copied && !err); | |
405 | return copied ? copied : err; | |
406 | } | |
407 | #else /* !CONFIG_HUGETLB_PAGE */ | |
408 | /* fail at build time if gcc attempts to use this */ | |
409 | extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, | |
410 | struct vm_area_struct *dst_vma, | |
411 | unsigned long dst_start, | |
412 | unsigned long src_start, | |
413 | unsigned long len, | |
414 | bool zeropage); | |
415 | #endif /* CONFIG_HUGETLB_PAGE */ | |
416 | ||
3217d3c7 MR |
417 | static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, |
418 | pmd_t *dst_pmd, | |
419 | struct vm_area_struct *dst_vma, | |
420 | unsigned long dst_addr, | |
421 | unsigned long src_addr, | |
422 | struct page **page, | |
72981e0e AA |
423 | bool zeropage, |
424 | bool wp_copy) | |
3217d3c7 MR |
425 | { |
426 | ssize_t err; | |
427 | ||
5b51072e AA |
428 | /* |
429 | * The normal page fault path for a shmem will invoke the | |
430 | * fault, fill the hole in the file and COW it right away. The | |
431 | * result generates plain anonymous memory. So when we are | |
432 | * asked to fill an hole in a MAP_PRIVATE shmem mapping, we'll | |
433 | * generate anonymous memory directly without actually filling | |
434 | * the hole. For the MAP_PRIVATE case the robustness check | |
435 | * only happens in the pagetable (to verify it's still none) | |
436 | * and not in the radix tree. | |
437 | */ | |
438 | if (!(dst_vma->vm_flags & VM_SHARED)) { | |
3217d3c7 MR |
439 | if (!zeropage) |
440 | err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, | |
72981e0e AA |
441 | dst_addr, src_addr, page, |
442 | wp_copy); | |
3217d3c7 MR |
443 | else |
444 | err = mfill_zeropage_pte(dst_mm, dst_pmd, | |
445 | dst_vma, dst_addr); | |
446 | } else { | |
72981e0e | 447 | VM_WARN_ON_ONCE(wp_copy); |
8fb44e54 | 448 | if (!zeropage) |
3217d3c7 MR |
449 | err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd, |
450 | dst_vma, dst_addr, | |
451 | src_addr, page); | |
8fb44e54 MR |
452 | else |
453 | err = shmem_mfill_zeropage_pte(dst_mm, dst_pmd, | |
454 | dst_vma, dst_addr); | |
3217d3c7 MR |
455 | } |
456 | ||
457 | return err; | |
458 | } | |
459 | ||
c1a4de99 AA |
460 | static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, |
461 | unsigned long dst_start, | |
462 | unsigned long src_start, | |
463 | unsigned long len, | |
df2cc96e | 464 | bool zeropage, |
72981e0e AA |
465 | bool *mmap_changing, |
466 | __u64 mode) | |
c1a4de99 AA |
467 | { |
468 | struct vm_area_struct *dst_vma; | |
469 | ssize_t err; | |
470 | pmd_t *dst_pmd; | |
471 | unsigned long src_addr, dst_addr; | |
b6ebaedb AA |
472 | long copied; |
473 | struct page *page; | |
72981e0e | 474 | bool wp_copy; |
c1a4de99 AA |
475 | |
476 | /* | |
477 | * Sanitize the command parameters: | |
478 | */ | |
479 | BUG_ON(dst_start & ~PAGE_MASK); | |
480 | BUG_ON(len & ~PAGE_MASK); | |
481 | ||
482 | /* Does the address range wrap, or is the span zero-sized? */ | |
483 | BUG_ON(src_start + len <= src_start); | |
484 | BUG_ON(dst_start + len <= dst_start); | |
485 | ||
b6ebaedb AA |
486 | src_addr = src_start; |
487 | dst_addr = dst_start; | |
488 | copied = 0; | |
489 | page = NULL; | |
490 | retry: | |
c1a4de99 AA |
491 | down_read(&dst_mm->mmap_sem); |
492 | ||
df2cc96e MR |
493 | /* |
494 | * If memory mappings are changing because of non-cooperative | |
495 | * operation (e.g. mremap) running in parallel, bail out and | |
496 | * request the user to retry later | |
497 | */ | |
498 | err = -EAGAIN; | |
499 | if (mmap_changing && READ_ONCE(*mmap_changing)) | |
500 | goto out_unlock; | |
501 | ||
c1a4de99 AA |
502 | /* |
503 | * Make sure the vma is not shared, that the dst range is | |
504 | * both valid and fully within a single existing vma. | |
505 | */ | |
27d02568 | 506 | err = -ENOENT; |
643aa36e | 507 | dst_vma = find_dst_vma(dst_mm, dst_start, len); |
26071ced MR |
508 | if (!dst_vma) |
509 | goto out_unlock; | |
c1a4de99 | 510 | |
27d02568 MR |
511 | err = -EINVAL; |
512 | /* | |
513 | * shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but | |
514 | * it will overwrite vm_ops, so vma_is_anonymous must return false. | |
515 | */ | |
516 | if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) && | |
517 | dst_vma->vm_flags & VM_SHARED)) | |
518 | goto out_unlock; | |
519 | ||
72981e0e AA |
520 | /* |
521 | * validate 'mode' now that we know the dst_vma: don't allow | |
522 | * a wrprotect copy if the userfaultfd didn't register as WP. | |
523 | */ | |
524 | wp_copy = mode & UFFDIO_COPY_MODE_WP; | |
525 | if (wp_copy && !(dst_vma->vm_flags & VM_UFFD_WP)) | |
526 | goto out_unlock; | |
527 | ||
60d4d2d2 MK |
528 | /* |
529 | * If this is a HUGETLB vma, pass off to appropriate routine | |
530 | */ | |
531 | if (is_vm_hugetlb_page(dst_vma)) | |
532 | return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start, | |
533 | src_start, len, zeropage); | |
534 | ||
26071ced | 535 | if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) |
b6ebaedb | 536 | goto out_unlock; |
c1a4de99 AA |
537 | |
538 | /* | |
539 | * Ensure the dst_vma has a anon_vma or this page | |
540 | * would get a NULL anon_vma when moved in the | |
541 | * dst_vma. | |
542 | */ | |
543 | err = -ENOMEM; | |
5b51072e AA |
544 | if (!(dst_vma->vm_flags & VM_SHARED) && |
545 | unlikely(anon_vma_prepare(dst_vma))) | |
b6ebaedb | 546 | goto out_unlock; |
c1a4de99 | 547 | |
b6ebaedb | 548 | while (src_addr < src_start + len) { |
c1a4de99 | 549 | pmd_t dst_pmdval; |
b6ebaedb | 550 | |
c1a4de99 | 551 | BUG_ON(dst_addr >= dst_start + len); |
b6ebaedb | 552 | |
c1a4de99 AA |
553 | dst_pmd = mm_alloc_pmd(dst_mm, dst_addr); |
554 | if (unlikely(!dst_pmd)) { | |
555 | err = -ENOMEM; | |
556 | break; | |
557 | } | |
558 | ||
559 | dst_pmdval = pmd_read_atomic(dst_pmd); | |
560 | /* | |
561 | * If the dst_pmd is mapped as THP don't | |
562 | * override it and just be strict. | |
563 | */ | |
564 | if (unlikely(pmd_trans_huge(dst_pmdval))) { | |
565 | err = -EEXIST; | |
566 | break; | |
567 | } | |
568 | if (unlikely(pmd_none(dst_pmdval)) && | |
4cf58924 | 569 | unlikely(__pte_alloc(dst_mm, dst_pmd))) { |
c1a4de99 AA |
570 | err = -ENOMEM; |
571 | break; | |
572 | } | |
573 | /* If an huge pmd materialized from under us fail */ | |
574 | if (unlikely(pmd_trans_huge(*dst_pmd))) { | |
575 | err = -EFAULT; | |
576 | break; | |
577 | } | |
578 | ||
579 | BUG_ON(pmd_none(*dst_pmd)); | |
580 | BUG_ON(pmd_trans_huge(*dst_pmd)); | |
581 | ||
3217d3c7 | 582 | err = mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, |
72981e0e | 583 | src_addr, &page, zeropage, wp_copy); |
c1a4de99 AA |
584 | cond_resched(); |
585 | ||
9e368259 | 586 | if (unlikely(err == -ENOENT)) { |
b6ebaedb AA |
587 | void *page_kaddr; |
588 | ||
589 | up_read(&dst_mm->mmap_sem); | |
590 | BUG_ON(!page); | |
591 | ||
592 | page_kaddr = kmap(page); | |
593 | err = copy_from_user(page_kaddr, | |
594 | (const void __user *) src_addr, | |
595 | PAGE_SIZE); | |
596 | kunmap(page); | |
597 | if (unlikely(err)) { | |
598 | err = -EFAULT; | |
599 | goto out; | |
600 | } | |
601 | goto retry; | |
602 | } else | |
603 | BUG_ON(page); | |
604 | ||
c1a4de99 AA |
605 | if (!err) { |
606 | dst_addr += PAGE_SIZE; | |
607 | src_addr += PAGE_SIZE; | |
608 | copied += PAGE_SIZE; | |
609 | ||
610 | if (fatal_signal_pending(current)) | |
611 | err = -EINTR; | |
612 | } | |
613 | if (err) | |
614 | break; | |
615 | } | |
616 | ||
b6ebaedb | 617 | out_unlock: |
c1a4de99 | 618 | up_read(&dst_mm->mmap_sem); |
b6ebaedb AA |
619 | out: |
620 | if (page) | |
09cbfeaf | 621 | put_page(page); |
c1a4de99 AA |
622 | BUG_ON(copied < 0); |
623 | BUG_ON(err > 0); | |
624 | BUG_ON(!copied && !err); | |
625 | return copied ? copied : err; | |
626 | } | |
627 | ||
628 | ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, | |
df2cc96e | 629 | unsigned long src_start, unsigned long len, |
72981e0e | 630 | bool *mmap_changing, __u64 mode) |
c1a4de99 | 631 | { |
df2cc96e | 632 | return __mcopy_atomic(dst_mm, dst_start, src_start, len, false, |
72981e0e | 633 | mmap_changing, mode); |
c1a4de99 AA |
634 | } |
635 | ||
636 | ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start, | |
df2cc96e | 637 | unsigned long len, bool *mmap_changing) |
c1a4de99 | 638 | { |
72981e0e | 639 | return __mcopy_atomic(dst_mm, start, 0, len, true, mmap_changing, 0); |
c1a4de99 | 640 | } |
ffd05793 SL |
641 | |
642 | int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, | |
643 | unsigned long len, bool enable_wp, bool *mmap_changing) | |
644 | { | |
645 | struct vm_area_struct *dst_vma; | |
646 | pgprot_t newprot; | |
647 | int err; | |
648 | ||
649 | /* | |
650 | * Sanitize the command parameters: | |
651 | */ | |
652 | BUG_ON(start & ~PAGE_MASK); | |
653 | BUG_ON(len & ~PAGE_MASK); | |
654 | ||
655 | /* Does the address range wrap, or is the span zero-sized? */ | |
656 | BUG_ON(start + len <= start); | |
657 | ||
658 | down_read(&dst_mm->mmap_sem); | |
659 | ||
660 | /* | |
661 | * If memory mappings are changing because of non-cooperative | |
662 | * operation (e.g. mremap) running in parallel, bail out and | |
663 | * request the user to retry later | |
664 | */ | |
665 | err = -EAGAIN; | |
666 | if (mmap_changing && READ_ONCE(*mmap_changing)) | |
667 | goto out_unlock; | |
668 | ||
669 | err = -ENOENT; | |
670 | dst_vma = find_dst_vma(dst_mm, start, len); | |
671 | /* | |
672 | * Make sure the vma is not shared, that the dst range is | |
673 | * both valid and fully within a single existing vma. | |
674 | */ | |
675 | if (!dst_vma || (dst_vma->vm_flags & VM_SHARED)) | |
676 | goto out_unlock; | |
677 | if (!userfaultfd_wp(dst_vma)) | |
678 | goto out_unlock; | |
679 | if (!vma_is_anonymous(dst_vma)) | |
680 | goto out_unlock; | |
681 | ||
682 | if (enable_wp) | |
683 | newprot = vm_get_page_prot(dst_vma->vm_flags & ~(VM_WRITE)); | |
684 | else | |
685 | newprot = vm_get_page_prot(dst_vma->vm_flags); | |
686 | ||
687 | change_protection(dst_vma, start, start + len, newprot, | |
688 | enable_wp ? MM_CP_UFFD_WP : MM_CP_UFFD_WP_RESOLVE); | |
689 | ||
690 | err = 0; | |
691 | out_unlock: | |
692 | up_read(&dst_mm->mmap_sem); | |
693 | return err; | |
694 | } |