Commit | Line | Data |
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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 | 58 | { |
c1a4de99 AA |
59 | pte_t _dst_pte, *dst_pte; |
60 | spinlock_t *ptl; | |
c1a4de99 AA |
61 | void *page_kaddr; |
62 | int ret; | |
b6ebaedb | 63 | struct page *page; |
e2a50c1f AA |
64 | pgoff_t offset, max_off; |
65 | struct inode *inode; | |
c1a4de99 | 66 | |
b6ebaedb AA |
67 | if (!*pagep) { |
68 | ret = -ENOMEM; | |
69 | page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr); | |
70 | if (!page) | |
71 | goto out; | |
72 | ||
73 | page_kaddr = kmap_atomic(page); | |
74 | ret = copy_from_user(page_kaddr, | |
75 | (const void __user *) src_addr, | |
76 | PAGE_SIZE); | |
77 | kunmap_atomic(page_kaddr); | |
78 | ||
c1e8d7c6 | 79 | /* fallback to copy_from_user outside mmap_lock */ |
b6ebaedb | 80 | if (unlikely(ret)) { |
9e368259 | 81 | ret = -ENOENT; |
b6ebaedb AA |
82 | *pagep = page; |
83 | /* don't free the page */ | |
84 | goto out; | |
85 | } | |
86 | } else { | |
87 | page = *pagep; | |
88 | *pagep = NULL; | |
89 | } | |
c1a4de99 AA |
90 | |
91 | /* | |
92 | * The memory barrier inside __SetPageUptodate makes sure that | |
f4f5329d | 93 | * preceding stores to the page contents become visible before |
c1a4de99 AA |
94 | * the set_pte_at() write. |
95 | */ | |
96 | __SetPageUptodate(page); | |
97 | ||
98 | ret = -ENOMEM; | |
d9eb1ea2 | 99 | if (mem_cgroup_charge(page, dst_mm, GFP_KERNEL)) |
c1a4de99 AA |
100 | goto out_release; |
101 | ||
72981e0e | 102 | _dst_pte = pte_mkdirty(mk_pte(page, dst_vma->vm_page_prot)); |
292924b2 PX |
103 | if (dst_vma->vm_flags & VM_WRITE) { |
104 | if (wp_copy) | |
105 | _dst_pte = pte_mkuffd_wp(_dst_pte); | |
106 | else | |
107 | _dst_pte = pte_mkwrite(_dst_pte); | |
108 | } | |
c1a4de99 | 109 | |
c1a4de99 | 110 | dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); |
e2a50c1f AA |
111 | if (dst_vma->vm_file) { |
112 | /* the shmem MAP_PRIVATE case requires checking the i_size */ | |
113 | inode = dst_vma->vm_file->f_inode; | |
114 | offset = linear_page_index(dst_vma, dst_addr); | |
115 | max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); | |
116 | ret = -EFAULT; | |
117 | if (unlikely(offset >= max_off)) | |
118 | goto out_release_uncharge_unlock; | |
119 | } | |
120 | ret = -EEXIST; | |
c1a4de99 AA |
121 | if (!pte_none(*dst_pte)) |
122 | goto out_release_uncharge_unlock; | |
123 | ||
124 | inc_mm_counter(dst_mm, MM_ANONPAGES); | |
be5d0a74 | 125 | page_add_new_anon_rmap(page, dst_vma, dst_addr, false); |
b518154e | 126 | lru_cache_add_inactive_or_unevictable(page, dst_vma); |
c1a4de99 AA |
127 | |
128 | set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); | |
129 | ||
130 | /* No need to invalidate - it was non-present before */ | |
131 | update_mmu_cache(dst_vma, dst_addr, dst_pte); | |
132 | ||
133 | pte_unmap_unlock(dst_pte, ptl); | |
134 | ret = 0; | |
135 | out: | |
136 | return ret; | |
137 | out_release_uncharge_unlock: | |
138 | pte_unmap_unlock(dst_pte, ptl); | |
c1a4de99 | 139 | out_release: |
09cbfeaf | 140 | put_page(page); |
c1a4de99 | 141 | goto out; |
c1a4de99 AA |
142 | } |
143 | ||
144 | static int mfill_zeropage_pte(struct mm_struct *dst_mm, | |
145 | pmd_t *dst_pmd, | |
146 | struct vm_area_struct *dst_vma, | |
147 | unsigned long dst_addr) | |
148 | { | |
149 | pte_t _dst_pte, *dst_pte; | |
150 | spinlock_t *ptl; | |
151 | int ret; | |
e2a50c1f AA |
152 | pgoff_t offset, max_off; |
153 | struct inode *inode; | |
c1a4de99 AA |
154 | |
155 | _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), | |
156 | dst_vma->vm_page_prot)); | |
c1a4de99 | 157 | dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); |
e2a50c1f AA |
158 | if (dst_vma->vm_file) { |
159 | /* the shmem MAP_PRIVATE case requires checking the i_size */ | |
160 | inode = dst_vma->vm_file->f_inode; | |
161 | offset = linear_page_index(dst_vma, dst_addr); | |
162 | max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); | |
163 | ret = -EFAULT; | |
164 | if (unlikely(offset >= max_off)) | |
165 | goto out_unlock; | |
166 | } | |
167 | ret = -EEXIST; | |
c1a4de99 AA |
168 | if (!pte_none(*dst_pte)) |
169 | goto out_unlock; | |
170 | set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); | |
171 | /* No need to invalidate - it was non-present before */ | |
172 | update_mmu_cache(dst_vma, dst_addr, dst_pte); | |
173 | ret = 0; | |
174 | out_unlock: | |
175 | pte_unmap_unlock(dst_pte, ptl); | |
176 | return ret; | |
177 | } | |
178 | ||
179 | static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address) | |
180 | { | |
181 | pgd_t *pgd; | |
c2febafc | 182 | p4d_t *p4d; |
c1a4de99 | 183 | pud_t *pud; |
c1a4de99 AA |
184 | |
185 | pgd = pgd_offset(mm, address); | |
c2febafc KS |
186 | p4d = p4d_alloc(mm, pgd, address); |
187 | if (!p4d) | |
188 | return NULL; | |
189 | pud = pud_alloc(mm, p4d, address); | |
190 | if (!pud) | |
191 | return NULL; | |
192 | /* | |
193 | * Note that we didn't run this because the pmd was | |
194 | * missing, the *pmd may be already established and in | |
195 | * turn it may also be a trans_huge_pmd. | |
196 | */ | |
197 | return pmd_alloc(mm, pud, address); | |
c1a4de99 AA |
198 | } |
199 | ||
60d4d2d2 MK |
200 | #ifdef CONFIG_HUGETLB_PAGE |
201 | /* | |
202 | * __mcopy_atomic processing for HUGETLB vmas. Note that this routine is | |
c1e8d7c6 | 203 | * called with mmap_lock held, it will release mmap_lock before returning. |
60d4d2d2 MK |
204 | */ |
205 | static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, | |
206 | struct vm_area_struct *dst_vma, | |
207 | unsigned long dst_start, | |
208 | unsigned long src_start, | |
209 | unsigned long len, | |
210 | bool zeropage) | |
211 | { | |
1c9e8def MK |
212 | int vm_alloc_shared = dst_vma->vm_flags & VM_SHARED; |
213 | int vm_shared = dst_vma->vm_flags & VM_SHARED; | |
60d4d2d2 MK |
214 | ssize_t err; |
215 | pte_t *dst_pte; | |
216 | unsigned long src_addr, dst_addr; | |
217 | long copied; | |
218 | struct page *page; | |
60d4d2d2 MK |
219 | unsigned long vma_hpagesize; |
220 | pgoff_t idx; | |
221 | u32 hash; | |
222 | struct address_space *mapping; | |
223 | ||
224 | /* | |
225 | * There is no default zero huge page for all huge page sizes as | |
226 | * supported by hugetlb. A PMD_SIZE huge pages may exist as used | |
227 | * by THP. Since we can not reliably insert a zero page, this | |
228 | * feature is not supported. | |
229 | */ | |
230 | if (zeropage) { | |
d8ed45c5 | 231 | mmap_read_unlock(dst_mm); |
60d4d2d2 MK |
232 | return -EINVAL; |
233 | } | |
234 | ||
235 | src_addr = src_start; | |
236 | dst_addr = dst_start; | |
237 | copied = 0; | |
238 | page = NULL; | |
239 | vma_hpagesize = vma_kernel_pagesize(dst_vma); | |
240 | ||
241 | /* | |
242 | * Validate alignment based on huge page size | |
243 | */ | |
244 | err = -EINVAL; | |
245 | if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1)) | |
246 | goto out_unlock; | |
247 | ||
248 | retry: | |
249 | /* | |
c1e8d7c6 | 250 | * On routine entry dst_vma is set. If we had to drop mmap_lock and |
60d4d2d2 MK |
251 | * retry, dst_vma will be set to NULL and we must lookup again. |
252 | */ | |
253 | if (!dst_vma) { | |
27d02568 | 254 | err = -ENOENT; |
643aa36e | 255 | dst_vma = find_dst_vma(dst_mm, dst_start, len); |
60d4d2d2 MK |
256 | if (!dst_vma || !is_vm_hugetlb_page(dst_vma)) |
257 | goto out_unlock; | |
1c9e8def | 258 | |
27d02568 MR |
259 | err = -EINVAL; |
260 | if (vma_hpagesize != vma_kernel_pagesize(dst_vma)) | |
261 | goto out_unlock; | |
262 | ||
1c9e8def | 263 | vm_shared = dst_vma->vm_flags & VM_SHARED; |
60d4d2d2 MK |
264 | } |
265 | ||
60d4d2d2 | 266 | /* |
1c9e8def | 267 | * If not shared, ensure the dst_vma has a anon_vma. |
60d4d2d2 MK |
268 | */ |
269 | err = -ENOMEM; | |
1c9e8def MK |
270 | if (!vm_shared) { |
271 | if (unlikely(anon_vma_prepare(dst_vma))) | |
272 | goto out_unlock; | |
273 | } | |
60d4d2d2 | 274 | |
60d4d2d2 MK |
275 | while (src_addr < src_start + len) { |
276 | pte_t dst_pteval; | |
277 | ||
278 | BUG_ON(dst_addr >= dst_start + len); | |
60d4d2d2 MK |
279 | |
280 | /* | |
c0d0381a MK |
281 | * Serialize via i_mmap_rwsem and hugetlb_fault_mutex. |
282 | * i_mmap_rwsem ensures the dst_pte remains valid even | |
283 | * in the case of shared pmds. fault mutex prevents | |
284 | * races with other faulting threads. | |
60d4d2d2 | 285 | */ |
ddeaab32 | 286 | mapping = dst_vma->vm_file->f_mapping; |
c0d0381a MK |
287 | i_mmap_lock_read(mapping); |
288 | idx = linear_page_index(dst_vma, dst_addr); | |
188b04a7 | 289 | hash = hugetlb_fault_mutex_hash(mapping, idx); |
60d4d2d2 MK |
290 | mutex_lock(&hugetlb_fault_mutex_table[hash]); |
291 | ||
292 | err = -ENOMEM; | |
4fb07ee6 | 293 | dst_pte = huge_pte_alloc(dst_mm, dst_addr, vma_hpagesize); |
60d4d2d2 MK |
294 | if (!dst_pte) { |
295 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); | |
c0d0381a | 296 | i_mmap_unlock_read(mapping); |
60d4d2d2 MK |
297 | goto out_unlock; |
298 | } | |
299 | ||
300 | err = -EEXIST; | |
301 | dst_pteval = huge_ptep_get(dst_pte); | |
302 | if (!huge_pte_none(dst_pteval)) { | |
303 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); | |
c0d0381a | 304 | i_mmap_unlock_read(mapping); |
60d4d2d2 MK |
305 | goto out_unlock; |
306 | } | |
307 | ||
308 | err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, | |
309 | dst_addr, src_addr, &page); | |
310 | ||
311 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); | |
c0d0381a | 312 | i_mmap_unlock_read(mapping); |
1c9e8def | 313 | vm_alloc_shared = vm_shared; |
60d4d2d2 MK |
314 | |
315 | cond_resched(); | |
316 | ||
9e368259 | 317 | if (unlikely(err == -ENOENT)) { |
d8ed45c5 | 318 | mmap_read_unlock(dst_mm); |
60d4d2d2 MK |
319 | BUG_ON(!page); |
320 | ||
321 | err = copy_huge_page_from_user(page, | |
322 | (const void __user *)src_addr, | |
4fb07ee6 WY |
323 | vma_hpagesize / PAGE_SIZE, |
324 | true); | |
60d4d2d2 MK |
325 | if (unlikely(err)) { |
326 | err = -EFAULT; | |
327 | goto out; | |
328 | } | |
d8ed45c5 | 329 | mmap_read_lock(dst_mm); |
60d4d2d2 MK |
330 | |
331 | dst_vma = NULL; | |
332 | goto retry; | |
333 | } else | |
334 | BUG_ON(page); | |
335 | ||
336 | if (!err) { | |
337 | dst_addr += vma_hpagesize; | |
338 | src_addr += vma_hpagesize; | |
339 | copied += vma_hpagesize; | |
340 | ||
341 | if (fatal_signal_pending(current)) | |
342 | err = -EINTR; | |
343 | } | |
344 | if (err) | |
345 | break; | |
346 | } | |
347 | ||
348 | out_unlock: | |
d8ed45c5 | 349 | mmap_read_unlock(dst_mm); |
60d4d2d2 | 350 | out: |
21205bf8 MK |
351 | if (page) { |
352 | /* | |
353 | * We encountered an error and are about to free a newly | |
1c9e8def MK |
354 | * allocated huge page. |
355 | * | |
356 | * Reservation handling is very subtle, and is different for | |
357 | * private and shared mappings. See the routine | |
358 | * restore_reserve_on_error for details. Unfortunately, we | |
359 | * can not call restore_reserve_on_error now as it would | |
c1e8d7c6 | 360 | * require holding mmap_lock. |
1c9e8def MK |
361 | * |
362 | * If a reservation for the page existed in the reservation | |
363 | * map of a private mapping, the map was modified to indicate | |
364 | * the reservation was consumed when the page was allocated. | |
365 | * We clear the PagePrivate flag now so that the global | |
21205bf8 MK |
366 | * reserve count will not be incremented in free_huge_page. |
367 | * The reservation map will still indicate the reservation | |
368 | * was consumed and possibly prevent later page allocation. | |
1c9e8def MK |
369 | * This is better than leaking a global reservation. If no |
370 | * reservation existed, it is still safe to clear PagePrivate | |
371 | * as no adjustments to reservation counts were made during | |
372 | * allocation. | |
373 | * | |
374 | * The reservation map for shared mappings indicates which | |
375 | * pages have reservations. When a huge page is allocated | |
376 | * for an address with a reservation, no change is made to | |
377 | * the reserve map. In this case PagePrivate will be set | |
378 | * to indicate that the global reservation count should be | |
379 | * incremented when the page is freed. This is the desired | |
380 | * behavior. However, when a huge page is allocated for an | |
381 | * address without a reservation a reservation entry is added | |
382 | * to the reservation map, and PagePrivate will not be set. | |
383 | * When the page is freed, the global reserve count will NOT | |
384 | * be incremented and it will appear as though we have leaked | |
385 | * reserved page. In this case, set PagePrivate so that the | |
386 | * global reserve count will be incremented to match the | |
387 | * reservation map entry which was created. | |
388 | * | |
389 | * Note that vm_alloc_shared is based on the flags of the vma | |
390 | * for which the page was originally allocated. dst_vma could | |
391 | * be different or NULL on error. | |
21205bf8 | 392 | */ |
1c9e8def MK |
393 | if (vm_alloc_shared) |
394 | SetPagePrivate(page); | |
395 | else | |
396 | ClearPagePrivate(page); | |
60d4d2d2 | 397 | put_page(page); |
21205bf8 | 398 | } |
60d4d2d2 MK |
399 | BUG_ON(copied < 0); |
400 | BUG_ON(err > 0); | |
401 | BUG_ON(!copied && !err); | |
402 | return copied ? copied : err; | |
403 | } | |
404 | #else /* !CONFIG_HUGETLB_PAGE */ | |
405 | /* fail at build time if gcc attempts to use this */ | |
406 | extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, | |
407 | struct vm_area_struct *dst_vma, | |
408 | unsigned long dst_start, | |
409 | unsigned long src_start, | |
410 | unsigned long len, | |
411 | bool zeropage); | |
412 | #endif /* CONFIG_HUGETLB_PAGE */ | |
413 | ||
3217d3c7 MR |
414 | static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, |
415 | pmd_t *dst_pmd, | |
416 | struct vm_area_struct *dst_vma, | |
417 | unsigned long dst_addr, | |
418 | unsigned long src_addr, | |
419 | struct page **page, | |
72981e0e AA |
420 | bool zeropage, |
421 | bool wp_copy) | |
3217d3c7 MR |
422 | { |
423 | ssize_t err; | |
424 | ||
5b51072e AA |
425 | /* |
426 | * The normal page fault path for a shmem will invoke the | |
427 | * fault, fill the hole in the file and COW it right away. The | |
428 | * result generates plain anonymous memory. So when we are | |
429 | * asked to fill an hole in a MAP_PRIVATE shmem mapping, we'll | |
430 | * generate anonymous memory directly without actually filling | |
431 | * the hole. For the MAP_PRIVATE case the robustness check | |
432 | * only happens in the pagetable (to verify it's still none) | |
433 | * and not in the radix tree. | |
434 | */ | |
435 | if (!(dst_vma->vm_flags & VM_SHARED)) { | |
3217d3c7 MR |
436 | if (!zeropage) |
437 | err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, | |
72981e0e AA |
438 | dst_addr, src_addr, page, |
439 | wp_copy); | |
3217d3c7 MR |
440 | else |
441 | err = mfill_zeropage_pte(dst_mm, dst_pmd, | |
442 | dst_vma, dst_addr); | |
443 | } else { | |
72981e0e | 444 | VM_WARN_ON_ONCE(wp_copy); |
8fb44e54 | 445 | if (!zeropage) |
3217d3c7 MR |
446 | err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd, |
447 | dst_vma, dst_addr, | |
448 | src_addr, page); | |
8fb44e54 MR |
449 | else |
450 | err = shmem_mfill_zeropage_pte(dst_mm, dst_pmd, | |
451 | dst_vma, dst_addr); | |
3217d3c7 MR |
452 | } |
453 | ||
454 | return err; | |
455 | } | |
456 | ||
c1a4de99 AA |
457 | static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, |
458 | unsigned long dst_start, | |
459 | unsigned long src_start, | |
460 | unsigned long len, | |
df2cc96e | 461 | bool zeropage, |
72981e0e AA |
462 | bool *mmap_changing, |
463 | __u64 mode) | |
c1a4de99 AA |
464 | { |
465 | struct vm_area_struct *dst_vma; | |
466 | ssize_t err; | |
467 | pmd_t *dst_pmd; | |
468 | unsigned long src_addr, dst_addr; | |
b6ebaedb AA |
469 | long copied; |
470 | struct page *page; | |
72981e0e | 471 | bool wp_copy; |
c1a4de99 AA |
472 | |
473 | /* | |
474 | * Sanitize the command parameters: | |
475 | */ | |
476 | BUG_ON(dst_start & ~PAGE_MASK); | |
477 | BUG_ON(len & ~PAGE_MASK); | |
478 | ||
479 | /* Does the address range wrap, or is the span zero-sized? */ | |
480 | BUG_ON(src_start + len <= src_start); | |
481 | BUG_ON(dst_start + len <= dst_start); | |
482 | ||
b6ebaedb AA |
483 | src_addr = src_start; |
484 | dst_addr = dst_start; | |
485 | copied = 0; | |
486 | page = NULL; | |
487 | retry: | |
d8ed45c5 | 488 | mmap_read_lock(dst_mm); |
c1a4de99 | 489 | |
df2cc96e MR |
490 | /* |
491 | * If memory mappings are changing because of non-cooperative | |
492 | * operation (e.g. mremap) running in parallel, bail out and | |
493 | * request the user to retry later | |
494 | */ | |
495 | err = -EAGAIN; | |
496 | if (mmap_changing && READ_ONCE(*mmap_changing)) | |
497 | goto out_unlock; | |
498 | ||
c1a4de99 AA |
499 | /* |
500 | * Make sure the vma is not shared, that the dst range is | |
501 | * both valid and fully within a single existing vma. | |
502 | */ | |
27d02568 | 503 | err = -ENOENT; |
643aa36e | 504 | dst_vma = find_dst_vma(dst_mm, dst_start, len); |
26071ced MR |
505 | if (!dst_vma) |
506 | goto out_unlock; | |
c1a4de99 | 507 | |
27d02568 MR |
508 | err = -EINVAL; |
509 | /* | |
510 | * shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but | |
511 | * it will overwrite vm_ops, so vma_is_anonymous must return false. | |
512 | */ | |
513 | if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) && | |
514 | dst_vma->vm_flags & VM_SHARED)) | |
515 | goto out_unlock; | |
516 | ||
72981e0e AA |
517 | /* |
518 | * validate 'mode' now that we know the dst_vma: don't allow | |
519 | * a wrprotect copy if the userfaultfd didn't register as WP. | |
520 | */ | |
521 | wp_copy = mode & UFFDIO_COPY_MODE_WP; | |
522 | if (wp_copy && !(dst_vma->vm_flags & VM_UFFD_WP)) | |
523 | goto out_unlock; | |
524 | ||
60d4d2d2 MK |
525 | /* |
526 | * If this is a HUGETLB vma, pass off to appropriate routine | |
527 | */ | |
528 | if (is_vm_hugetlb_page(dst_vma)) | |
529 | return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start, | |
530 | src_start, len, zeropage); | |
531 | ||
26071ced | 532 | if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) |
b6ebaedb | 533 | goto out_unlock; |
c1a4de99 AA |
534 | |
535 | /* | |
536 | * Ensure the dst_vma has a anon_vma or this page | |
537 | * would get a NULL anon_vma when moved in the | |
538 | * dst_vma. | |
539 | */ | |
540 | err = -ENOMEM; | |
5b51072e AA |
541 | if (!(dst_vma->vm_flags & VM_SHARED) && |
542 | unlikely(anon_vma_prepare(dst_vma))) | |
b6ebaedb | 543 | goto out_unlock; |
c1a4de99 | 544 | |
b6ebaedb | 545 | while (src_addr < src_start + len) { |
c1a4de99 | 546 | pmd_t dst_pmdval; |
b6ebaedb | 547 | |
c1a4de99 | 548 | BUG_ON(dst_addr >= dst_start + len); |
b6ebaedb | 549 | |
c1a4de99 AA |
550 | dst_pmd = mm_alloc_pmd(dst_mm, dst_addr); |
551 | if (unlikely(!dst_pmd)) { | |
552 | err = -ENOMEM; | |
553 | break; | |
554 | } | |
555 | ||
556 | dst_pmdval = pmd_read_atomic(dst_pmd); | |
557 | /* | |
558 | * If the dst_pmd is mapped as THP don't | |
559 | * override it and just be strict. | |
560 | */ | |
561 | if (unlikely(pmd_trans_huge(dst_pmdval))) { | |
562 | err = -EEXIST; | |
563 | break; | |
564 | } | |
565 | if (unlikely(pmd_none(dst_pmdval)) && | |
4cf58924 | 566 | unlikely(__pte_alloc(dst_mm, dst_pmd))) { |
c1a4de99 AA |
567 | err = -ENOMEM; |
568 | break; | |
569 | } | |
570 | /* If an huge pmd materialized from under us fail */ | |
571 | if (unlikely(pmd_trans_huge(*dst_pmd))) { | |
572 | err = -EFAULT; | |
573 | break; | |
574 | } | |
575 | ||
576 | BUG_ON(pmd_none(*dst_pmd)); | |
577 | BUG_ON(pmd_trans_huge(*dst_pmd)); | |
578 | ||
3217d3c7 | 579 | err = mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, |
72981e0e | 580 | src_addr, &page, zeropage, wp_copy); |
c1a4de99 AA |
581 | cond_resched(); |
582 | ||
9e368259 | 583 | if (unlikely(err == -ENOENT)) { |
b6ebaedb AA |
584 | void *page_kaddr; |
585 | ||
d8ed45c5 | 586 | mmap_read_unlock(dst_mm); |
b6ebaedb AA |
587 | BUG_ON(!page); |
588 | ||
589 | page_kaddr = kmap(page); | |
590 | err = copy_from_user(page_kaddr, | |
591 | (const void __user *) src_addr, | |
592 | PAGE_SIZE); | |
593 | kunmap(page); | |
594 | if (unlikely(err)) { | |
595 | err = -EFAULT; | |
596 | goto out; | |
597 | } | |
598 | goto retry; | |
599 | } else | |
600 | BUG_ON(page); | |
601 | ||
c1a4de99 AA |
602 | if (!err) { |
603 | dst_addr += PAGE_SIZE; | |
604 | src_addr += PAGE_SIZE; | |
605 | copied += PAGE_SIZE; | |
606 | ||
607 | if (fatal_signal_pending(current)) | |
608 | err = -EINTR; | |
609 | } | |
610 | if (err) | |
611 | break; | |
612 | } | |
613 | ||
b6ebaedb | 614 | out_unlock: |
d8ed45c5 | 615 | mmap_read_unlock(dst_mm); |
b6ebaedb AA |
616 | out: |
617 | if (page) | |
09cbfeaf | 618 | put_page(page); |
c1a4de99 AA |
619 | BUG_ON(copied < 0); |
620 | BUG_ON(err > 0); | |
621 | BUG_ON(!copied && !err); | |
622 | return copied ? copied : err; | |
623 | } | |
624 | ||
625 | ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, | |
df2cc96e | 626 | unsigned long src_start, unsigned long len, |
72981e0e | 627 | bool *mmap_changing, __u64 mode) |
c1a4de99 | 628 | { |
df2cc96e | 629 | return __mcopy_atomic(dst_mm, dst_start, src_start, len, false, |
72981e0e | 630 | mmap_changing, mode); |
c1a4de99 AA |
631 | } |
632 | ||
633 | ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start, | |
df2cc96e | 634 | unsigned long len, bool *mmap_changing) |
c1a4de99 | 635 | { |
72981e0e | 636 | return __mcopy_atomic(dst_mm, start, 0, len, true, mmap_changing, 0); |
c1a4de99 | 637 | } |
ffd05793 SL |
638 | |
639 | int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, | |
640 | unsigned long len, bool enable_wp, bool *mmap_changing) | |
641 | { | |
642 | struct vm_area_struct *dst_vma; | |
643 | pgprot_t newprot; | |
644 | int err; | |
645 | ||
646 | /* | |
647 | * Sanitize the command parameters: | |
648 | */ | |
649 | BUG_ON(start & ~PAGE_MASK); | |
650 | BUG_ON(len & ~PAGE_MASK); | |
651 | ||
652 | /* Does the address range wrap, or is the span zero-sized? */ | |
653 | BUG_ON(start + len <= start); | |
654 | ||
d8ed45c5 | 655 | mmap_read_lock(dst_mm); |
ffd05793 SL |
656 | |
657 | /* | |
658 | * If memory mappings are changing because of non-cooperative | |
659 | * operation (e.g. mremap) running in parallel, bail out and | |
660 | * request the user to retry later | |
661 | */ | |
662 | err = -EAGAIN; | |
663 | if (mmap_changing && READ_ONCE(*mmap_changing)) | |
664 | goto out_unlock; | |
665 | ||
666 | err = -ENOENT; | |
667 | dst_vma = find_dst_vma(dst_mm, start, len); | |
668 | /* | |
669 | * Make sure the vma is not shared, that the dst range is | |
670 | * both valid and fully within a single existing vma. | |
671 | */ | |
672 | if (!dst_vma || (dst_vma->vm_flags & VM_SHARED)) | |
673 | goto out_unlock; | |
674 | if (!userfaultfd_wp(dst_vma)) | |
675 | goto out_unlock; | |
676 | if (!vma_is_anonymous(dst_vma)) | |
677 | goto out_unlock; | |
678 | ||
679 | if (enable_wp) | |
680 | newprot = vm_get_page_prot(dst_vma->vm_flags & ~(VM_WRITE)); | |
681 | else | |
682 | newprot = vm_get_page_prot(dst_vma->vm_flags); | |
683 | ||
684 | change_protection(dst_vma, start, start + len, newprot, | |
685 | enable_wp ? MM_CP_UFFD_WP : MM_CP_UFFD_WP_RESOLVE); | |
686 | ||
687 | err = 0; | |
688 | out_unlock: | |
d8ed45c5 | 689 | mmap_read_unlock(dst_mm); |
ffd05793 SL |
690 | return err; |
691 | } |