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 | 18 | #include <asm/tlbflush.h> |
4a18419f | 19 | #include <asm/tlb.h> |
c1a4de99 AA |
20 | #include "internal.h" |
21 | ||
643aa36e WY |
22 | static __always_inline |
23 | struct vm_area_struct *find_dst_vma(struct mm_struct *dst_mm, | |
24 | unsigned long dst_start, | |
25 | unsigned long len) | |
26 | { | |
27 | /* | |
28 | * Make sure that the dst range is both valid and fully within a | |
29 | * single existing vma. | |
30 | */ | |
31 | struct vm_area_struct *dst_vma; | |
32 | ||
33 | dst_vma = find_vma(dst_mm, dst_start); | |
34 | if (!dst_vma) | |
35 | return NULL; | |
36 | ||
37 | if (dst_start < dst_vma->vm_start || | |
38 | dst_start + len > dst_vma->vm_end) | |
39 | return NULL; | |
40 | ||
41 | /* | |
42 | * Check the vma is registered in uffd, this is required to | |
43 | * enforce the VM_MAYWRITE check done at uffd registration | |
44 | * time. | |
45 | */ | |
46 | if (!dst_vma->vm_userfaultfd_ctx.ctx) | |
47 | return NULL; | |
48 | ||
49 | return dst_vma; | |
50 | } | |
51 | ||
15313257 AR |
52 | /* |
53 | * Install PTEs, to map dst_addr (within dst_vma) to page. | |
54 | * | |
7d64ae3a AR |
55 | * This function handles both MCOPY_ATOMIC_NORMAL and _CONTINUE for both shmem |
56 | * and anon, and for both shared and private VMAs. | |
15313257 | 57 | */ |
7d64ae3a AR |
58 | int mfill_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, |
59 | struct vm_area_struct *dst_vma, | |
60 | unsigned long dst_addr, struct page *page, | |
61 | bool newly_allocated, bool wp_copy) | |
15313257 AR |
62 | { |
63 | int ret; | |
64 | pte_t _dst_pte, *dst_pte; | |
65 | bool writable = dst_vma->vm_flags & VM_WRITE; | |
66 | bool vm_shared = dst_vma->vm_flags & VM_SHARED; | |
93b0d917 | 67 | bool page_in_cache = page_mapping(page); |
15313257 | 68 | spinlock_t *ptl; |
28965f0f | 69 | struct folio *folio; |
15313257 AR |
70 | struct inode *inode; |
71 | pgoff_t offset, max_off; | |
72 | ||
73 | _dst_pte = mk_pte(page, dst_vma->vm_page_prot); | |
9ae0f87d | 74 | _dst_pte = pte_mkdirty(_dst_pte); |
15313257 AR |
75 | if (page_in_cache && !vm_shared) |
76 | writable = false; | |
0e88904c NA |
77 | |
78 | /* | |
79 | * Always mark a PTE as write-protected when needed, regardless of | |
80 | * VM_WRITE, which the user might change. | |
81 | */ | |
8ee79edf | 82 | if (wp_copy) { |
0e88904c | 83 | _dst_pte = pte_mkuffd_wp(_dst_pte); |
8ee79edf PX |
84 | writable = false; |
85 | } | |
86 | ||
87 | if (writable) | |
0e88904c | 88 | _dst_pte = pte_mkwrite(_dst_pte); |
8ee79edf PX |
89 | else |
90 | /* | |
91 | * We need this to make sure write bit removed; as mk_pte() | |
92 | * could return a pte with write bit set. | |
93 | */ | |
94 | _dst_pte = pte_wrprotect(_dst_pte); | |
15313257 AR |
95 | |
96 | dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); | |
97 | ||
98 | if (vma_is_shmem(dst_vma)) { | |
99 | /* serialize against truncate with the page table lock */ | |
100 | inode = dst_vma->vm_file->f_inode; | |
101 | offset = linear_page_index(dst_vma, dst_addr); | |
102 | max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); | |
103 | ret = -EFAULT; | |
104 | if (unlikely(offset >= max_off)) | |
105 | goto out_unlock; | |
106 | } | |
107 | ||
108 | ret = -EEXIST; | |
8ee79edf PX |
109 | /* |
110 | * We allow to overwrite a pte marker: consider when both MISSING|WP | |
111 | * registered, we firstly wr-protect a none pte which has no page cache | |
112 | * page backing it, then access the page. | |
113 | */ | |
114 | if (!pte_none_mostly(*dst_pte)) | |
15313257 AR |
115 | goto out_unlock; |
116 | ||
28965f0f | 117 | folio = page_folio(page); |
cea86fe2 HD |
118 | if (page_in_cache) { |
119 | /* Usually, cache pages are already added to LRU */ | |
120 | if (newly_allocated) | |
28965f0f | 121 | folio_add_lru(folio); |
cea86fe2 HD |
122 | page_add_file_rmap(page, dst_vma, false); |
123 | } else { | |
40f2bbf7 | 124 | page_add_new_anon_rmap(page, dst_vma, dst_addr); |
28965f0f | 125 | folio_add_lru_vma(folio, dst_vma); |
cea86fe2 | 126 | } |
15313257 AR |
127 | |
128 | /* | |
129 | * Must happen after rmap, as mm_counter() checks mapping (via | |
130 | * PageAnon()), which is set by __page_set_anon_rmap(). | |
131 | */ | |
132 | inc_mm_counter(dst_mm, mm_counter(page)); | |
133 | ||
15313257 AR |
134 | set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); |
135 | ||
136 | /* No need to invalidate - it was non-present before */ | |
137 | update_mmu_cache(dst_vma, dst_addr, dst_pte); | |
138 | ret = 0; | |
139 | out_unlock: | |
140 | pte_unmap_unlock(dst_pte, ptl); | |
141 | return ret; | |
142 | } | |
143 | ||
c1a4de99 AA |
144 | static int mcopy_atomic_pte(struct mm_struct *dst_mm, |
145 | pmd_t *dst_pmd, | |
146 | struct vm_area_struct *dst_vma, | |
147 | unsigned long dst_addr, | |
b6ebaedb | 148 | unsigned long src_addr, |
72981e0e AA |
149 | struct page **pagep, |
150 | bool wp_copy) | |
c1a4de99 | 151 | { |
c1a4de99 AA |
152 | void *page_kaddr; |
153 | int ret; | |
b6ebaedb | 154 | struct page *page; |
c1a4de99 | 155 | |
b6ebaedb AA |
156 | if (!*pagep) { |
157 | ret = -ENOMEM; | |
158 | page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr); | |
159 | if (!page) | |
160 | goto out; | |
161 | ||
5521de7d IW |
162 | page_kaddr = kmap_local_page(page); |
163 | /* | |
164 | * The read mmap_lock is held here. Despite the | |
165 | * mmap_lock being read recursive a deadlock is still | |
166 | * possible if a writer has taken a lock. For example: | |
167 | * | |
168 | * process A thread 1 takes read lock on own mmap_lock | |
169 | * process A thread 2 calls mmap, blocks taking write lock | |
170 | * process B thread 1 takes page fault, read lock on own mmap lock | |
171 | * process B thread 2 calls mmap, blocks taking write lock | |
172 | * process A thread 1 blocks taking read lock on process B | |
173 | * process B thread 1 blocks taking read lock on process A | |
174 | * | |
175 | * Disable page faults to prevent potential deadlock | |
176 | * and retry the copy outside the mmap_lock. | |
177 | */ | |
178 | pagefault_disable(); | |
b6ebaedb AA |
179 | ret = copy_from_user(page_kaddr, |
180 | (const void __user *) src_addr, | |
181 | PAGE_SIZE); | |
5521de7d IW |
182 | pagefault_enable(); |
183 | kunmap_local(page_kaddr); | |
b6ebaedb | 184 | |
c1e8d7c6 | 185 | /* fallback to copy_from_user outside mmap_lock */ |
b6ebaedb | 186 | if (unlikely(ret)) { |
9e368259 | 187 | ret = -ENOENT; |
b6ebaedb AA |
188 | *pagep = page; |
189 | /* don't free the page */ | |
190 | goto out; | |
191 | } | |
7c25a0b8 MS |
192 | |
193 | flush_dcache_page(page); | |
b6ebaedb AA |
194 | } else { |
195 | page = *pagep; | |
196 | *pagep = NULL; | |
197 | } | |
c1a4de99 AA |
198 | |
199 | /* | |
200 | * The memory barrier inside __SetPageUptodate makes sure that | |
f4f5329d | 201 | * preceding stores to the page contents become visible before |
c1a4de99 AA |
202 | * the set_pte_at() write. |
203 | */ | |
204 | __SetPageUptodate(page); | |
205 | ||
206 | ret = -ENOMEM; | |
8f425e4e | 207 | if (mem_cgroup_charge(page_folio(page), dst_mm, GFP_KERNEL)) |
c1a4de99 AA |
208 | goto out_release; |
209 | ||
15313257 AR |
210 | ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr, |
211 | page, true, wp_copy); | |
212 | if (ret) | |
213 | goto out_release; | |
c1a4de99 AA |
214 | out: |
215 | return ret; | |
c1a4de99 | 216 | out_release: |
09cbfeaf | 217 | put_page(page); |
c1a4de99 | 218 | goto out; |
c1a4de99 AA |
219 | } |
220 | ||
221 | static int mfill_zeropage_pte(struct mm_struct *dst_mm, | |
222 | pmd_t *dst_pmd, | |
223 | struct vm_area_struct *dst_vma, | |
224 | unsigned long dst_addr) | |
225 | { | |
226 | pte_t _dst_pte, *dst_pte; | |
227 | spinlock_t *ptl; | |
228 | int ret; | |
e2a50c1f AA |
229 | pgoff_t offset, max_off; |
230 | struct inode *inode; | |
c1a4de99 AA |
231 | |
232 | _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), | |
233 | dst_vma->vm_page_prot)); | |
c1a4de99 | 234 | dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); |
e2a50c1f AA |
235 | if (dst_vma->vm_file) { |
236 | /* the shmem MAP_PRIVATE case requires checking the i_size */ | |
237 | inode = dst_vma->vm_file->f_inode; | |
238 | offset = linear_page_index(dst_vma, dst_addr); | |
239 | max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); | |
240 | ret = -EFAULT; | |
241 | if (unlikely(offset >= max_off)) | |
242 | goto out_unlock; | |
243 | } | |
244 | ret = -EEXIST; | |
c1a4de99 AA |
245 | if (!pte_none(*dst_pte)) |
246 | goto out_unlock; | |
247 | set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); | |
248 | /* No need to invalidate - it was non-present before */ | |
249 | update_mmu_cache(dst_vma, dst_addr, dst_pte); | |
250 | ret = 0; | |
251 | out_unlock: | |
252 | pte_unmap_unlock(dst_pte, ptl); | |
253 | return ret; | |
254 | } | |
255 | ||
15313257 AR |
256 | /* Handles UFFDIO_CONTINUE for all shmem VMAs (shared or private). */ |
257 | static int mcontinue_atomic_pte(struct mm_struct *dst_mm, | |
258 | pmd_t *dst_pmd, | |
259 | struct vm_area_struct *dst_vma, | |
260 | unsigned long dst_addr, | |
261 | bool wp_copy) | |
262 | { | |
263 | struct inode *inode = file_inode(dst_vma->vm_file); | |
264 | pgoff_t pgoff = linear_page_index(dst_vma, dst_addr); | |
12acf4fb | 265 | struct folio *folio; |
15313257 AR |
266 | struct page *page; |
267 | int ret; | |
268 | ||
12acf4fb MWO |
269 | ret = shmem_get_folio(inode, pgoff, &folio, SGP_NOALLOC); |
270 | /* Our caller expects us to return -EFAULT if we failed to find folio */ | |
73f37dbc AR |
271 | if (ret == -ENOENT) |
272 | ret = -EFAULT; | |
15313257 AR |
273 | if (ret) |
274 | goto out; | |
12acf4fb | 275 | if (!folio) { |
15313257 AR |
276 | ret = -EFAULT; |
277 | goto out; | |
278 | } | |
279 | ||
12acf4fb | 280 | page = folio_file_page(folio, pgoff); |
a7605426 YS |
281 | if (PageHWPoison(page)) { |
282 | ret = -EIO; | |
283 | goto out_release; | |
284 | } | |
285 | ||
15313257 AR |
286 | ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr, |
287 | page, false, wp_copy); | |
288 | if (ret) | |
289 | goto out_release; | |
290 | ||
12acf4fb | 291 | folio_unlock(folio); |
15313257 AR |
292 | ret = 0; |
293 | out: | |
294 | return ret; | |
295 | out_release: | |
12acf4fb MWO |
296 | folio_unlock(folio); |
297 | folio_put(folio); | |
15313257 AR |
298 | goto out; |
299 | } | |
300 | ||
c1a4de99 AA |
301 | static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address) |
302 | { | |
303 | pgd_t *pgd; | |
c2febafc | 304 | p4d_t *p4d; |
c1a4de99 | 305 | pud_t *pud; |
c1a4de99 AA |
306 | |
307 | pgd = pgd_offset(mm, address); | |
c2febafc KS |
308 | p4d = p4d_alloc(mm, pgd, address); |
309 | if (!p4d) | |
310 | return NULL; | |
311 | pud = pud_alloc(mm, p4d, address); | |
312 | if (!pud) | |
313 | return NULL; | |
314 | /* | |
315 | * Note that we didn't run this because the pmd was | |
316 | * missing, the *pmd may be already established and in | |
317 | * turn it may also be a trans_huge_pmd. | |
318 | */ | |
319 | return pmd_alloc(mm, pud, address); | |
c1a4de99 AA |
320 | } |
321 | ||
60d4d2d2 MK |
322 | #ifdef CONFIG_HUGETLB_PAGE |
323 | /* | |
324 | * __mcopy_atomic processing for HUGETLB vmas. Note that this routine is | |
c1e8d7c6 | 325 | * called with mmap_lock held, it will release mmap_lock before returning. |
60d4d2d2 MK |
326 | */ |
327 | static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, | |
328 | struct vm_area_struct *dst_vma, | |
329 | unsigned long dst_start, | |
330 | unsigned long src_start, | |
331 | unsigned long len, | |
6041c691 PX |
332 | enum mcopy_atomic_mode mode, |
333 | bool wp_copy) | |
60d4d2d2 | 334 | { |
1c9e8def | 335 | int vm_shared = dst_vma->vm_flags & VM_SHARED; |
60d4d2d2 MK |
336 | ssize_t err; |
337 | pte_t *dst_pte; | |
338 | unsigned long src_addr, dst_addr; | |
339 | long copied; | |
340 | struct page *page; | |
60d4d2d2 MK |
341 | unsigned long vma_hpagesize; |
342 | pgoff_t idx; | |
343 | u32 hash; | |
344 | struct address_space *mapping; | |
345 | ||
346 | /* | |
347 | * There is no default zero huge page for all huge page sizes as | |
348 | * supported by hugetlb. A PMD_SIZE huge pages may exist as used | |
349 | * by THP. Since we can not reliably insert a zero page, this | |
350 | * feature is not supported. | |
351 | */ | |
f6191471 | 352 | if (mode == MCOPY_ATOMIC_ZEROPAGE) { |
d8ed45c5 | 353 | mmap_read_unlock(dst_mm); |
60d4d2d2 MK |
354 | return -EINVAL; |
355 | } | |
356 | ||
357 | src_addr = src_start; | |
358 | dst_addr = dst_start; | |
359 | copied = 0; | |
360 | page = NULL; | |
361 | vma_hpagesize = vma_kernel_pagesize(dst_vma); | |
362 | ||
363 | /* | |
364 | * Validate alignment based on huge page size | |
365 | */ | |
366 | err = -EINVAL; | |
367 | if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1)) | |
368 | goto out_unlock; | |
369 | ||
370 | retry: | |
371 | /* | |
c1e8d7c6 | 372 | * On routine entry dst_vma is set. If we had to drop mmap_lock and |
60d4d2d2 MK |
373 | * retry, dst_vma will be set to NULL and we must lookup again. |
374 | */ | |
375 | if (!dst_vma) { | |
27d02568 | 376 | err = -ENOENT; |
643aa36e | 377 | dst_vma = find_dst_vma(dst_mm, dst_start, len); |
60d4d2d2 MK |
378 | if (!dst_vma || !is_vm_hugetlb_page(dst_vma)) |
379 | goto out_unlock; | |
1c9e8def | 380 | |
27d02568 MR |
381 | err = -EINVAL; |
382 | if (vma_hpagesize != vma_kernel_pagesize(dst_vma)) | |
383 | goto out_unlock; | |
384 | ||
1c9e8def | 385 | vm_shared = dst_vma->vm_flags & VM_SHARED; |
60d4d2d2 MK |
386 | } |
387 | ||
60d4d2d2 | 388 | /* |
1c9e8def | 389 | * If not shared, ensure the dst_vma has a anon_vma. |
60d4d2d2 MK |
390 | */ |
391 | err = -ENOMEM; | |
1c9e8def MK |
392 | if (!vm_shared) { |
393 | if (unlikely(anon_vma_prepare(dst_vma))) | |
394 | goto out_unlock; | |
395 | } | |
60d4d2d2 | 396 | |
60d4d2d2 | 397 | while (src_addr < src_start + len) { |
60d4d2d2 | 398 | BUG_ON(dst_addr >= dst_start + len); |
60d4d2d2 MK |
399 | |
400 | /* | |
40549ba8 MK |
401 | * Serialize via vma_lock and hugetlb_fault_mutex. |
402 | * vma_lock ensures the dst_pte remains valid even | |
403 | * in the case of shared pmds. fault mutex prevents | |
404 | * races with other faulting threads. | |
60d4d2d2 | 405 | */ |
c0d0381a | 406 | idx = linear_page_index(dst_vma, dst_addr); |
3a47c54f | 407 | mapping = dst_vma->vm_file->f_mapping; |
188b04a7 | 408 | hash = hugetlb_fault_mutex_hash(mapping, idx); |
60d4d2d2 | 409 | mutex_lock(&hugetlb_fault_mutex_table[hash]); |
40549ba8 | 410 | hugetlb_vma_lock_read(dst_vma); |
60d4d2d2 MK |
411 | |
412 | err = -ENOMEM; | |
aec44e0f | 413 | dst_pte = huge_pte_alloc(dst_mm, dst_vma, dst_addr, vma_hpagesize); |
60d4d2d2 | 414 | if (!dst_pte) { |
40549ba8 | 415 | hugetlb_vma_unlock_read(dst_vma); |
60d4d2d2 MK |
416 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); |
417 | goto out_unlock; | |
418 | } | |
419 | ||
f6191471 | 420 | if (mode != MCOPY_ATOMIC_CONTINUE && |
6041c691 | 421 | !huge_pte_none_mostly(huge_ptep_get(dst_pte))) { |
f6191471 | 422 | err = -EEXIST; |
40549ba8 | 423 | hugetlb_vma_unlock_read(dst_vma); |
60d4d2d2 MK |
424 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); |
425 | goto out_unlock; | |
426 | } | |
427 | ||
428 | err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, | |
6041c691 PX |
429 | dst_addr, src_addr, mode, &page, |
430 | wp_copy); | |
60d4d2d2 | 431 | |
40549ba8 | 432 | hugetlb_vma_unlock_read(dst_vma); |
60d4d2d2 MK |
433 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); |
434 | ||
435 | cond_resched(); | |
436 | ||
9e368259 | 437 | if (unlikely(err == -ENOENT)) { |
d8ed45c5 | 438 | mmap_read_unlock(dst_mm); |
60d4d2d2 MK |
439 | BUG_ON(!page); |
440 | ||
441 | err = copy_huge_page_from_user(page, | |
442 | (const void __user *)src_addr, | |
4fb07ee6 WY |
443 | vma_hpagesize / PAGE_SIZE, |
444 | true); | |
60d4d2d2 MK |
445 | if (unlikely(err)) { |
446 | err = -EFAULT; | |
447 | goto out; | |
448 | } | |
d8ed45c5 | 449 | mmap_read_lock(dst_mm); |
60d4d2d2 MK |
450 | |
451 | dst_vma = NULL; | |
452 | goto retry; | |
453 | } else | |
454 | BUG_ON(page); | |
455 | ||
456 | if (!err) { | |
457 | dst_addr += vma_hpagesize; | |
458 | src_addr += vma_hpagesize; | |
459 | copied += vma_hpagesize; | |
460 | ||
461 | if (fatal_signal_pending(current)) | |
462 | err = -EINTR; | |
463 | } | |
464 | if (err) | |
465 | break; | |
466 | } | |
467 | ||
468 | out_unlock: | |
d8ed45c5 | 469 | mmap_read_unlock(dst_mm); |
60d4d2d2 | 470 | out: |
8cc5fcbb | 471 | if (page) |
60d4d2d2 MK |
472 | put_page(page); |
473 | BUG_ON(copied < 0); | |
474 | BUG_ON(err > 0); | |
475 | BUG_ON(!copied && !err); | |
476 | return copied ? copied : err; | |
477 | } | |
478 | #else /* !CONFIG_HUGETLB_PAGE */ | |
479 | /* fail at build time if gcc attempts to use this */ | |
480 | extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, | |
481 | struct vm_area_struct *dst_vma, | |
482 | unsigned long dst_start, | |
483 | unsigned long src_start, | |
484 | unsigned long len, | |
6041c691 PX |
485 | enum mcopy_atomic_mode mode, |
486 | bool wp_copy); | |
60d4d2d2 MK |
487 | #endif /* CONFIG_HUGETLB_PAGE */ |
488 | ||
3217d3c7 MR |
489 | static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, |
490 | pmd_t *dst_pmd, | |
491 | struct vm_area_struct *dst_vma, | |
492 | unsigned long dst_addr, | |
493 | unsigned long src_addr, | |
494 | struct page **page, | |
15313257 | 495 | enum mcopy_atomic_mode mode, |
72981e0e | 496 | bool wp_copy) |
3217d3c7 MR |
497 | { |
498 | ssize_t err; | |
499 | ||
15313257 AR |
500 | if (mode == MCOPY_ATOMIC_CONTINUE) { |
501 | return mcontinue_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, | |
502 | wp_copy); | |
503 | } | |
504 | ||
5b51072e AA |
505 | /* |
506 | * The normal page fault path for a shmem will invoke the | |
507 | * fault, fill the hole in the file and COW it right away. The | |
508 | * result generates plain anonymous memory. So when we are | |
509 | * asked to fill an hole in a MAP_PRIVATE shmem mapping, we'll | |
510 | * generate anonymous memory directly without actually filling | |
511 | * the hole. For the MAP_PRIVATE case the robustness check | |
512 | * only happens in the pagetable (to verify it's still none) | |
513 | * and not in the radix tree. | |
514 | */ | |
515 | if (!(dst_vma->vm_flags & VM_SHARED)) { | |
15313257 | 516 | if (mode == MCOPY_ATOMIC_NORMAL) |
3217d3c7 | 517 | err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, |
72981e0e AA |
518 | dst_addr, src_addr, page, |
519 | wp_copy); | |
3217d3c7 MR |
520 | else |
521 | err = mfill_zeropage_pte(dst_mm, dst_pmd, | |
522 | dst_vma, dst_addr); | |
523 | } else { | |
3460f6e5 | 524 | err = shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, |
15313257 AR |
525 | dst_addr, src_addr, |
526 | mode != MCOPY_ATOMIC_NORMAL, | |
8ee79edf | 527 | wp_copy, page); |
3217d3c7 MR |
528 | } |
529 | ||
530 | return err; | |
531 | } | |
532 | ||
c1a4de99 AA |
533 | static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, |
534 | unsigned long dst_start, | |
535 | unsigned long src_start, | |
536 | unsigned long len, | |
f6191471 | 537 | enum mcopy_atomic_mode mcopy_mode, |
a759a909 | 538 | atomic_t *mmap_changing, |
72981e0e | 539 | __u64 mode) |
c1a4de99 AA |
540 | { |
541 | struct vm_area_struct *dst_vma; | |
542 | ssize_t err; | |
543 | pmd_t *dst_pmd; | |
544 | unsigned long src_addr, dst_addr; | |
b6ebaedb AA |
545 | long copied; |
546 | struct page *page; | |
72981e0e | 547 | bool wp_copy; |
c1a4de99 AA |
548 | |
549 | /* | |
550 | * Sanitize the command parameters: | |
551 | */ | |
552 | BUG_ON(dst_start & ~PAGE_MASK); | |
553 | BUG_ON(len & ~PAGE_MASK); | |
554 | ||
555 | /* Does the address range wrap, or is the span zero-sized? */ | |
556 | BUG_ON(src_start + len <= src_start); | |
557 | BUG_ON(dst_start + len <= dst_start); | |
558 | ||
b6ebaedb AA |
559 | src_addr = src_start; |
560 | dst_addr = dst_start; | |
561 | copied = 0; | |
562 | page = NULL; | |
563 | retry: | |
d8ed45c5 | 564 | mmap_read_lock(dst_mm); |
c1a4de99 | 565 | |
df2cc96e MR |
566 | /* |
567 | * If memory mappings are changing because of non-cooperative | |
568 | * operation (e.g. mremap) running in parallel, bail out and | |
569 | * request the user to retry later | |
570 | */ | |
571 | err = -EAGAIN; | |
a759a909 | 572 | if (mmap_changing && atomic_read(mmap_changing)) |
df2cc96e MR |
573 | goto out_unlock; |
574 | ||
c1a4de99 AA |
575 | /* |
576 | * Make sure the vma is not shared, that the dst range is | |
577 | * both valid and fully within a single existing vma. | |
578 | */ | |
27d02568 | 579 | err = -ENOENT; |
643aa36e | 580 | dst_vma = find_dst_vma(dst_mm, dst_start, len); |
26071ced MR |
581 | if (!dst_vma) |
582 | goto out_unlock; | |
c1a4de99 | 583 | |
27d02568 MR |
584 | err = -EINVAL; |
585 | /* | |
586 | * shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but | |
587 | * it will overwrite vm_ops, so vma_is_anonymous must return false. | |
588 | */ | |
589 | if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) && | |
590 | dst_vma->vm_flags & VM_SHARED)) | |
591 | goto out_unlock; | |
592 | ||
72981e0e AA |
593 | /* |
594 | * validate 'mode' now that we know the dst_vma: don't allow | |
595 | * a wrprotect copy if the userfaultfd didn't register as WP. | |
596 | */ | |
597 | wp_copy = mode & UFFDIO_COPY_MODE_WP; | |
598 | if (wp_copy && !(dst_vma->vm_flags & VM_UFFD_WP)) | |
599 | goto out_unlock; | |
600 | ||
60d4d2d2 MK |
601 | /* |
602 | * If this is a HUGETLB vma, pass off to appropriate routine | |
603 | */ | |
604 | if (is_vm_hugetlb_page(dst_vma)) | |
605 | return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start, | |
6041c691 PX |
606 | src_start, len, mcopy_mode, |
607 | wp_copy); | |
60d4d2d2 | 608 | |
26071ced | 609 | if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) |
b6ebaedb | 610 | goto out_unlock; |
15313257 | 611 | if (!vma_is_shmem(dst_vma) && mcopy_mode == MCOPY_ATOMIC_CONTINUE) |
f6191471 | 612 | goto out_unlock; |
c1a4de99 AA |
613 | |
614 | /* | |
615 | * Ensure the dst_vma has a anon_vma or this page | |
616 | * would get a NULL anon_vma when moved in the | |
617 | * dst_vma. | |
618 | */ | |
619 | err = -ENOMEM; | |
5b51072e AA |
620 | if (!(dst_vma->vm_flags & VM_SHARED) && |
621 | unlikely(anon_vma_prepare(dst_vma))) | |
b6ebaedb | 622 | goto out_unlock; |
c1a4de99 | 623 | |
b6ebaedb | 624 | while (src_addr < src_start + len) { |
c1a4de99 | 625 | pmd_t dst_pmdval; |
b6ebaedb | 626 | |
c1a4de99 | 627 | BUG_ON(dst_addr >= dst_start + len); |
b6ebaedb | 628 | |
c1a4de99 AA |
629 | dst_pmd = mm_alloc_pmd(dst_mm, dst_addr); |
630 | if (unlikely(!dst_pmd)) { | |
631 | err = -ENOMEM; | |
632 | break; | |
633 | } | |
634 | ||
635 | dst_pmdval = pmd_read_atomic(dst_pmd); | |
636 | /* | |
637 | * If the dst_pmd is mapped as THP don't | |
638 | * override it and just be strict. | |
639 | */ | |
640 | if (unlikely(pmd_trans_huge(dst_pmdval))) { | |
641 | err = -EEXIST; | |
642 | break; | |
643 | } | |
644 | if (unlikely(pmd_none(dst_pmdval)) && | |
4cf58924 | 645 | unlikely(__pte_alloc(dst_mm, dst_pmd))) { |
c1a4de99 AA |
646 | err = -ENOMEM; |
647 | break; | |
648 | } | |
649 | /* If an huge pmd materialized from under us fail */ | |
650 | if (unlikely(pmd_trans_huge(*dst_pmd))) { | |
651 | err = -EFAULT; | |
652 | break; | |
653 | } | |
654 | ||
655 | BUG_ON(pmd_none(*dst_pmd)); | |
656 | BUG_ON(pmd_trans_huge(*dst_pmd)); | |
657 | ||
3217d3c7 | 658 | err = mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, |
15313257 | 659 | src_addr, &page, mcopy_mode, wp_copy); |
c1a4de99 AA |
660 | cond_resched(); |
661 | ||
9e368259 | 662 | if (unlikely(err == -ENOENT)) { |
b6ebaedb AA |
663 | void *page_kaddr; |
664 | ||
d8ed45c5 | 665 | mmap_read_unlock(dst_mm); |
b6ebaedb AA |
666 | BUG_ON(!page); |
667 | ||
5521de7d | 668 | page_kaddr = kmap_local_page(page); |
b6ebaedb AA |
669 | err = copy_from_user(page_kaddr, |
670 | (const void __user *) src_addr, | |
671 | PAGE_SIZE); | |
5521de7d | 672 | kunmap_local(page_kaddr); |
b6ebaedb AA |
673 | if (unlikely(err)) { |
674 | err = -EFAULT; | |
675 | goto out; | |
676 | } | |
7c25a0b8 | 677 | flush_dcache_page(page); |
b6ebaedb AA |
678 | goto retry; |
679 | } else | |
680 | BUG_ON(page); | |
681 | ||
c1a4de99 AA |
682 | if (!err) { |
683 | dst_addr += PAGE_SIZE; | |
684 | src_addr += PAGE_SIZE; | |
685 | copied += PAGE_SIZE; | |
686 | ||
687 | if (fatal_signal_pending(current)) | |
688 | err = -EINTR; | |
689 | } | |
690 | if (err) | |
691 | break; | |
692 | } | |
693 | ||
b6ebaedb | 694 | out_unlock: |
d8ed45c5 | 695 | mmap_read_unlock(dst_mm); |
b6ebaedb AA |
696 | out: |
697 | if (page) | |
09cbfeaf | 698 | put_page(page); |
c1a4de99 AA |
699 | BUG_ON(copied < 0); |
700 | BUG_ON(err > 0); | |
701 | BUG_ON(!copied && !err); | |
702 | return copied ? copied : err; | |
703 | } | |
704 | ||
705 | ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, | |
df2cc96e | 706 | unsigned long src_start, unsigned long len, |
a759a909 | 707 | atomic_t *mmap_changing, __u64 mode) |
c1a4de99 | 708 | { |
f6191471 AR |
709 | return __mcopy_atomic(dst_mm, dst_start, src_start, len, |
710 | MCOPY_ATOMIC_NORMAL, mmap_changing, mode); | |
c1a4de99 AA |
711 | } |
712 | ||
713 | ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start, | |
a759a909 | 714 | unsigned long len, atomic_t *mmap_changing) |
c1a4de99 | 715 | { |
f6191471 AR |
716 | return __mcopy_atomic(dst_mm, start, 0, len, MCOPY_ATOMIC_ZEROPAGE, |
717 | mmap_changing, 0); | |
718 | } | |
719 | ||
720 | ssize_t mcopy_continue(struct mm_struct *dst_mm, unsigned long start, | |
a759a909 | 721 | unsigned long len, atomic_t *mmap_changing) |
f6191471 AR |
722 | { |
723 | return __mcopy_atomic(dst_mm, start, 0, len, MCOPY_ATOMIC_CONTINUE, | |
724 | mmap_changing, 0); | |
c1a4de99 | 725 | } |
ffd05793 | 726 | |
f369b07c PX |
727 | void uffd_wp_range(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma, |
728 | unsigned long start, unsigned long len, bool enable_wp) | |
729 | { | |
730 | struct mmu_gather tlb; | |
731 | pgprot_t newprot; | |
732 | ||
733 | if (enable_wp) | |
734 | newprot = vm_get_page_prot(dst_vma->vm_flags & ~(VM_WRITE)); | |
735 | else | |
736 | newprot = vm_get_page_prot(dst_vma->vm_flags); | |
737 | ||
738 | tlb_gather_mmu(&tlb, dst_mm); | |
739 | change_protection(&tlb, dst_vma, start, start + len, newprot, | |
740 | enable_wp ? MM_CP_UFFD_WP : MM_CP_UFFD_WP_RESOLVE); | |
741 | tlb_finish_mmu(&tlb); | |
742 | } | |
743 | ||
ffd05793 | 744 | int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, |
a759a909 NA |
745 | unsigned long len, bool enable_wp, |
746 | atomic_t *mmap_changing) | |
ffd05793 SL |
747 | { |
748 | struct vm_area_struct *dst_vma; | |
5a90d5a1 | 749 | unsigned long page_mask; |
ffd05793 SL |
750 | int err; |
751 | ||
752 | /* | |
753 | * Sanitize the command parameters: | |
754 | */ | |
755 | BUG_ON(start & ~PAGE_MASK); | |
756 | BUG_ON(len & ~PAGE_MASK); | |
757 | ||
758 | /* Does the address range wrap, or is the span zero-sized? */ | |
759 | BUG_ON(start + len <= start); | |
760 | ||
d8ed45c5 | 761 | mmap_read_lock(dst_mm); |
ffd05793 SL |
762 | |
763 | /* | |
764 | * If memory mappings are changing because of non-cooperative | |
765 | * operation (e.g. mremap) running in parallel, bail out and | |
766 | * request the user to retry later | |
767 | */ | |
768 | err = -EAGAIN; | |
a759a909 | 769 | if (mmap_changing && atomic_read(mmap_changing)) |
ffd05793 SL |
770 | goto out_unlock; |
771 | ||
772 | err = -ENOENT; | |
773 | dst_vma = find_dst_vma(dst_mm, start, len); | |
b1f9e876 PX |
774 | |
775 | if (!dst_vma) | |
ffd05793 SL |
776 | goto out_unlock; |
777 | if (!userfaultfd_wp(dst_vma)) | |
778 | goto out_unlock; | |
b1f9e876 | 779 | if (!vma_can_userfault(dst_vma, dst_vma->vm_flags)) |
ffd05793 SL |
780 | goto out_unlock; |
781 | ||
5a90d5a1 PX |
782 | if (is_vm_hugetlb_page(dst_vma)) { |
783 | err = -EINVAL; | |
784 | page_mask = vma_kernel_pagesize(dst_vma) - 1; | |
785 | if ((start & page_mask) || (len & page_mask)) | |
786 | goto out_unlock; | |
787 | } | |
788 | ||
f369b07c | 789 | uffd_wp_range(dst_mm, dst_vma, start, len, enable_wp); |
ffd05793 SL |
790 | |
791 | err = 0; | |
792 | out_unlock: | |
d8ed45c5 | 793 | mmap_read_unlock(dst_mm); |
ffd05793 SL |
794 | return err; |
795 | } |