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); | |
686ea6e6 | 34 | if (!range_in_vma(dst_vma, dst_start, dst_start + len)) |
643aa36e WY |
35 | return NULL; |
36 | ||
37 | /* | |
38 | * Check the vma is registered in uffd, this is required to | |
39 | * enforce the VM_MAYWRITE check done at uffd registration | |
40 | * time. | |
41 | */ | |
42 | if (!dst_vma->vm_userfaultfd_ctx.ctx) | |
43 | return NULL; | |
44 | ||
45 | return dst_vma; | |
46 | } | |
47 | ||
435cdb41 AR |
48 | /* Check if dst_addr is outside of file's size. Must be called with ptl held. */ |
49 | static bool mfill_file_over_size(struct vm_area_struct *dst_vma, | |
50 | unsigned long dst_addr) | |
51 | { | |
52 | struct inode *inode; | |
53 | pgoff_t offset, max_off; | |
54 | ||
55 | if (!dst_vma->vm_file) | |
56 | return false; | |
57 | ||
58 | inode = dst_vma->vm_file->f_inode; | |
59 | offset = linear_page_index(dst_vma, dst_addr); | |
60 | max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); | |
61 | return offset >= max_off; | |
62 | } | |
63 | ||
15313257 AR |
64 | /* |
65 | * Install PTEs, to map dst_addr (within dst_vma) to page. | |
66 | * | |
7d64ae3a AR |
67 | * This function handles both MCOPY_ATOMIC_NORMAL and _CONTINUE for both shmem |
68 | * and anon, and for both shared and private VMAs. | |
15313257 | 69 | */ |
61c50040 | 70 | int mfill_atomic_install_pte(pmd_t *dst_pmd, |
7d64ae3a AR |
71 | struct vm_area_struct *dst_vma, |
72 | unsigned long dst_addr, struct page *page, | |
d9712937 | 73 | bool newly_allocated, uffd_flags_t flags) |
15313257 AR |
74 | { |
75 | int ret; | |
61c50040 | 76 | struct mm_struct *dst_mm = dst_vma->vm_mm; |
15313257 AR |
77 | pte_t _dst_pte, *dst_pte; |
78 | bool writable = dst_vma->vm_flags & VM_WRITE; | |
79 | bool vm_shared = dst_vma->vm_flags & VM_SHARED; | |
93b0d917 | 80 | bool page_in_cache = page_mapping(page); |
15313257 | 81 | spinlock_t *ptl; |
28965f0f | 82 | struct folio *folio; |
15313257 AR |
83 | |
84 | _dst_pte = mk_pte(page, dst_vma->vm_page_prot); | |
9ae0f87d | 85 | _dst_pte = pte_mkdirty(_dst_pte); |
15313257 AR |
86 | if (page_in_cache && !vm_shared) |
87 | writable = false; | |
8ee79edf | 88 | if (writable) |
0e88904c | 89 | _dst_pte = pte_mkwrite(_dst_pte); |
d9712937 | 90 | if (flags & MFILL_ATOMIC_WP) |
f1eb1bac | 91 | _dst_pte = pte_mkuffd_wp(_dst_pte); |
15313257 | 92 | |
3622d3cd | 93 | ret = -EAGAIN; |
15313257 | 94 | dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); |
3622d3cd HD |
95 | if (!dst_pte) |
96 | goto out; | |
15313257 | 97 | |
435cdb41 | 98 | if (mfill_file_over_size(dst_vma, dst_addr)) { |
15313257 | 99 | ret = -EFAULT; |
435cdb41 | 100 | goto out_unlock; |
15313257 AR |
101 | } |
102 | ||
103 | ret = -EEXIST; | |
8ee79edf PX |
104 | /* |
105 | * We allow to overwrite a pte marker: consider when both MISSING|WP | |
106 | * registered, we firstly wr-protect a none pte which has no page cache | |
107 | * page backing it, then access the page. | |
108 | */ | |
c33c7948 | 109 | if (!pte_none_mostly(ptep_get(dst_pte))) |
15313257 AR |
110 | goto out_unlock; |
111 | ||
28965f0f | 112 | folio = page_folio(page); |
cea86fe2 HD |
113 | if (page_in_cache) { |
114 | /* Usually, cache pages are already added to LRU */ | |
115 | if (newly_allocated) | |
28965f0f | 116 | folio_add_lru(folio); |
cea86fe2 HD |
117 | page_add_file_rmap(page, dst_vma, false); |
118 | } else { | |
40f2bbf7 | 119 | page_add_new_anon_rmap(page, dst_vma, dst_addr); |
28965f0f | 120 | folio_add_lru_vma(folio, dst_vma); |
cea86fe2 | 121 | } |
15313257 AR |
122 | |
123 | /* | |
124 | * Must happen after rmap, as mm_counter() checks mapping (via | |
125 | * PageAnon()), which is set by __page_set_anon_rmap(). | |
126 | */ | |
127 | inc_mm_counter(dst_mm, mm_counter(page)); | |
128 | ||
15313257 AR |
129 | set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); |
130 | ||
131 | /* No need to invalidate - it was non-present before */ | |
132 | update_mmu_cache(dst_vma, dst_addr, dst_pte); | |
133 | ret = 0; | |
134 | out_unlock: | |
135 | pte_unmap_unlock(dst_pte, ptl); | |
3622d3cd | 136 | out: |
15313257 AR |
137 | return ret; |
138 | } | |
139 | ||
61c50040 | 140 | static int mfill_atomic_pte_copy(pmd_t *dst_pmd, |
a734991c AR |
141 | struct vm_area_struct *dst_vma, |
142 | unsigned long dst_addr, | |
143 | unsigned long src_addr, | |
d9712937 | 144 | uffd_flags_t flags, |
d7be6d7e | 145 | struct folio **foliop) |
c1a4de99 | 146 | { |
07e6d409 | 147 | void *kaddr; |
c1a4de99 | 148 | int ret; |
07e6d409 | 149 | struct folio *folio; |
c1a4de99 | 150 | |
d7be6d7e | 151 | if (!*foliop) { |
b6ebaedb | 152 | ret = -ENOMEM; |
07e6d409 Z |
153 | folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, dst_vma, |
154 | dst_addr, false); | |
155 | if (!folio) | |
b6ebaedb AA |
156 | goto out; |
157 | ||
07e6d409 | 158 | kaddr = kmap_local_folio(folio, 0); |
5521de7d IW |
159 | /* |
160 | * The read mmap_lock is held here. Despite the | |
161 | * mmap_lock being read recursive a deadlock is still | |
162 | * possible if a writer has taken a lock. For example: | |
163 | * | |
164 | * process A thread 1 takes read lock on own mmap_lock | |
165 | * process A thread 2 calls mmap, blocks taking write lock | |
166 | * process B thread 1 takes page fault, read lock on own mmap lock | |
167 | * process B thread 2 calls mmap, blocks taking write lock | |
168 | * process A thread 1 blocks taking read lock on process B | |
169 | * process B thread 1 blocks taking read lock on process A | |
170 | * | |
171 | * Disable page faults to prevent potential deadlock | |
172 | * and retry the copy outside the mmap_lock. | |
173 | */ | |
174 | pagefault_disable(); | |
07e6d409 | 175 | ret = copy_from_user(kaddr, (const void __user *) src_addr, |
b6ebaedb | 176 | PAGE_SIZE); |
5521de7d | 177 | pagefault_enable(); |
07e6d409 | 178 | kunmap_local(kaddr); |
b6ebaedb | 179 | |
c1e8d7c6 | 180 | /* fallback to copy_from_user outside mmap_lock */ |
b6ebaedb | 181 | if (unlikely(ret)) { |
9e368259 | 182 | ret = -ENOENT; |
d7be6d7e | 183 | *foliop = folio; |
b6ebaedb AA |
184 | /* don't free the page */ |
185 | goto out; | |
186 | } | |
7c25a0b8 | 187 | |
07e6d409 | 188 | flush_dcache_folio(folio); |
b6ebaedb | 189 | } else { |
d7be6d7e Z |
190 | folio = *foliop; |
191 | *foliop = NULL; | |
b6ebaedb | 192 | } |
c1a4de99 AA |
193 | |
194 | /* | |
07e6d409 | 195 | * The memory barrier inside __folio_mark_uptodate makes sure that |
f4f5329d | 196 | * preceding stores to the page contents become visible before |
c1a4de99 AA |
197 | * the set_pte_at() write. |
198 | */ | |
07e6d409 | 199 | __folio_mark_uptodate(folio); |
c1a4de99 AA |
200 | |
201 | ret = -ENOMEM; | |
07e6d409 | 202 | if (mem_cgroup_charge(folio, dst_vma->vm_mm, GFP_KERNEL)) |
c1a4de99 AA |
203 | goto out_release; |
204 | ||
61c50040 | 205 | ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr, |
07e6d409 | 206 | &folio->page, true, flags); |
15313257 AR |
207 | if (ret) |
208 | goto out_release; | |
c1a4de99 AA |
209 | out: |
210 | return ret; | |
c1a4de99 | 211 | out_release: |
07e6d409 | 212 | folio_put(folio); |
c1a4de99 | 213 | goto out; |
c1a4de99 AA |
214 | } |
215 | ||
61c50040 | 216 | static int mfill_atomic_pte_zeropage(pmd_t *dst_pmd, |
a734991c AR |
217 | struct vm_area_struct *dst_vma, |
218 | unsigned long dst_addr) | |
c1a4de99 AA |
219 | { |
220 | pte_t _dst_pte, *dst_pte; | |
221 | spinlock_t *ptl; | |
222 | int ret; | |
223 | ||
224 | _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), | |
225 | dst_vma->vm_page_prot)); | |
3622d3cd | 226 | ret = -EAGAIN; |
61c50040 | 227 | dst_pte = pte_offset_map_lock(dst_vma->vm_mm, dst_pmd, dst_addr, &ptl); |
3622d3cd HD |
228 | if (!dst_pte) |
229 | goto out; | |
435cdb41 | 230 | if (mfill_file_over_size(dst_vma, dst_addr)) { |
e2a50c1f | 231 | ret = -EFAULT; |
435cdb41 | 232 | goto out_unlock; |
e2a50c1f AA |
233 | } |
234 | ret = -EEXIST; | |
c33c7948 | 235 | if (!pte_none(ptep_get(dst_pte))) |
c1a4de99 | 236 | goto out_unlock; |
61c50040 | 237 | set_pte_at(dst_vma->vm_mm, dst_addr, dst_pte, _dst_pte); |
c1a4de99 AA |
238 | /* No need to invalidate - it was non-present before */ |
239 | update_mmu_cache(dst_vma, dst_addr, dst_pte); | |
240 | ret = 0; | |
241 | out_unlock: | |
242 | pte_unmap_unlock(dst_pte, ptl); | |
3622d3cd | 243 | out: |
c1a4de99 AA |
244 | return ret; |
245 | } | |
246 | ||
15313257 | 247 | /* Handles UFFDIO_CONTINUE for all shmem VMAs (shared or private). */ |
61c50040 | 248 | static int mfill_atomic_pte_continue(pmd_t *dst_pmd, |
a734991c AR |
249 | struct vm_area_struct *dst_vma, |
250 | unsigned long dst_addr, | |
d9712937 | 251 | uffd_flags_t flags) |
15313257 AR |
252 | { |
253 | struct inode *inode = file_inode(dst_vma->vm_file); | |
254 | pgoff_t pgoff = linear_page_index(dst_vma, dst_addr); | |
12acf4fb | 255 | struct folio *folio; |
15313257 AR |
256 | struct page *page; |
257 | int ret; | |
258 | ||
12acf4fb MWO |
259 | ret = shmem_get_folio(inode, pgoff, &folio, SGP_NOALLOC); |
260 | /* Our caller expects us to return -EFAULT if we failed to find folio */ | |
73f37dbc AR |
261 | if (ret == -ENOENT) |
262 | ret = -EFAULT; | |
15313257 AR |
263 | if (ret) |
264 | goto out; | |
12acf4fb | 265 | if (!folio) { |
15313257 AR |
266 | ret = -EFAULT; |
267 | goto out; | |
268 | } | |
269 | ||
12acf4fb | 270 | page = folio_file_page(folio, pgoff); |
a7605426 YS |
271 | if (PageHWPoison(page)) { |
272 | ret = -EIO; | |
273 | goto out_release; | |
274 | } | |
275 | ||
61c50040 | 276 | ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr, |
d9712937 | 277 | page, false, flags); |
15313257 AR |
278 | if (ret) |
279 | goto out_release; | |
280 | ||
12acf4fb | 281 | folio_unlock(folio); |
15313257 AR |
282 | ret = 0; |
283 | out: | |
284 | return ret; | |
285 | out_release: | |
12acf4fb MWO |
286 | folio_unlock(folio); |
287 | folio_put(folio); | |
15313257 AR |
288 | goto out; |
289 | } | |
290 | ||
fc71884a AR |
291 | /* Handles UFFDIO_POISON for all non-hugetlb VMAs. */ |
292 | static int mfill_atomic_pte_poison(pmd_t *dst_pmd, | |
293 | struct vm_area_struct *dst_vma, | |
294 | unsigned long dst_addr, | |
295 | uffd_flags_t flags) | |
296 | { | |
297 | int ret; | |
298 | struct mm_struct *dst_mm = dst_vma->vm_mm; | |
299 | pte_t _dst_pte, *dst_pte; | |
300 | spinlock_t *ptl; | |
301 | ||
302 | _dst_pte = make_pte_marker(PTE_MARKER_POISONED); | |
597425df | 303 | ret = -EAGAIN; |
fc71884a | 304 | dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); |
597425df HD |
305 | if (!dst_pte) |
306 | goto out; | |
fc71884a AR |
307 | |
308 | if (mfill_file_over_size(dst_vma, dst_addr)) { | |
309 | ret = -EFAULT; | |
310 | goto out_unlock; | |
311 | } | |
312 | ||
313 | ret = -EEXIST; | |
314 | /* Refuse to overwrite any PTE, even a PTE marker (e.g. UFFD WP). */ | |
315 | if (!pte_none(*dst_pte)) | |
316 | goto out_unlock; | |
317 | ||
318 | set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); | |
319 | ||
320 | /* No need to invalidate - it was non-present before */ | |
321 | update_mmu_cache(dst_vma, dst_addr, dst_pte); | |
322 | ret = 0; | |
323 | out_unlock: | |
324 | pte_unmap_unlock(dst_pte, ptl); | |
597425df | 325 | out: |
fc71884a AR |
326 | return ret; |
327 | } | |
328 | ||
c1a4de99 AA |
329 | static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address) |
330 | { | |
331 | pgd_t *pgd; | |
c2febafc | 332 | p4d_t *p4d; |
c1a4de99 | 333 | pud_t *pud; |
c1a4de99 AA |
334 | |
335 | pgd = pgd_offset(mm, address); | |
c2febafc KS |
336 | p4d = p4d_alloc(mm, pgd, address); |
337 | if (!p4d) | |
338 | return NULL; | |
339 | pud = pud_alloc(mm, p4d, address); | |
340 | if (!pud) | |
341 | return NULL; | |
342 | /* | |
343 | * Note that we didn't run this because the pmd was | |
344 | * missing, the *pmd may be already established and in | |
345 | * turn it may also be a trans_huge_pmd. | |
346 | */ | |
347 | return pmd_alloc(mm, pud, address); | |
c1a4de99 AA |
348 | } |
349 | ||
60d4d2d2 MK |
350 | #ifdef CONFIG_HUGETLB_PAGE |
351 | /* | |
a734991c | 352 | * mfill_atomic processing for HUGETLB vmas. Note that this routine is |
c1e8d7c6 | 353 | * called with mmap_lock held, it will release mmap_lock before returning. |
60d4d2d2 | 354 | */ |
61c50040 | 355 | static __always_inline ssize_t mfill_atomic_hugetlb( |
60d4d2d2 MK |
356 | struct vm_area_struct *dst_vma, |
357 | unsigned long dst_start, | |
358 | unsigned long src_start, | |
359 | unsigned long len, | |
d9712937 | 360 | uffd_flags_t flags) |
60d4d2d2 | 361 | { |
61c50040 | 362 | struct mm_struct *dst_mm = dst_vma->vm_mm; |
1c9e8def | 363 | int vm_shared = dst_vma->vm_flags & VM_SHARED; |
60d4d2d2 MK |
364 | ssize_t err; |
365 | pte_t *dst_pte; | |
366 | unsigned long src_addr, dst_addr; | |
367 | long copied; | |
0169fd51 | 368 | struct folio *folio; |
60d4d2d2 MK |
369 | unsigned long vma_hpagesize; |
370 | pgoff_t idx; | |
371 | u32 hash; | |
372 | struct address_space *mapping; | |
373 | ||
374 | /* | |
375 | * There is no default zero huge page for all huge page sizes as | |
376 | * supported by hugetlb. A PMD_SIZE huge pages may exist as used | |
377 | * by THP. Since we can not reliably insert a zero page, this | |
378 | * feature is not supported. | |
379 | */ | |
fc71884a AR |
380 | if (uffd_flags_mode_is(flags, MFILL_ATOMIC_ZEROPAGE) || |
381 | uffd_flags_mode_is(flags, MFILL_ATOMIC_POISON)) { | |
d8ed45c5 | 382 | mmap_read_unlock(dst_mm); |
60d4d2d2 MK |
383 | return -EINVAL; |
384 | } | |
385 | ||
386 | src_addr = src_start; | |
387 | dst_addr = dst_start; | |
388 | copied = 0; | |
0169fd51 | 389 | folio = NULL; |
60d4d2d2 MK |
390 | vma_hpagesize = vma_kernel_pagesize(dst_vma); |
391 | ||
392 | /* | |
393 | * Validate alignment based on huge page size | |
394 | */ | |
395 | err = -EINVAL; | |
396 | if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1)) | |
397 | goto out_unlock; | |
398 | ||
399 | retry: | |
400 | /* | |
c1e8d7c6 | 401 | * On routine entry dst_vma is set. If we had to drop mmap_lock and |
60d4d2d2 MK |
402 | * retry, dst_vma will be set to NULL and we must lookup again. |
403 | */ | |
404 | if (!dst_vma) { | |
27d02568 | 405 | err = -ENOENT; |
643aa36e | 406 | dst_vma = find_dst_vma(dst_mm, dst_start, len); |
60d4d2d2 MK |
407 | if (!dst_vma || !is_vm_hugetlb_page(dst_vma)) |
408 | goto out_unlock; | |
1c9e8def | 409 | |
27d02568 MR |
410 | err = -EINVAL; |
411 | if (vma_hpagesize != vma_kernel_pagesize(dst_vma)) | |
412 | goto out_unlock; | |
413 | ||
1c9e8def | 414 | vm_shared = dst_vma->vm_flags & VM_SHARED; |
60d4d2d2 MK |
415 | } |
416 | ||
60d4d2d2 | 417 | /* |
1c9e8def | 418 | * If not shared, ensure the dst_vma has a anon_vma. |
60d4d2d2 MK |
419 | */ |
420 | err = -ENOMEM; | |
1c9e8def MK |
421 | if (!vm_shared) { |
422 | if (unlikely(anon_vma_prepare(dst_vma))) | |
423 | goto out_unlock; | |
424 | } | |
60d4d2d2 | 425 | |
60d4d2d2 | 426 | while (src_addr < src_start + len) { |
60d4d2d2 | 427 | BUG_ON(dst_addr >= dst_start + len); |
60d4d2d2 MK |
428 | |
429 | /* | |
40549ba8 MK |
430 | * Serialize via vma_lock and hugetlb_fault_mutex. |
431 | * vma_lock ensures the dst_pte remains valid even | |
432 | * in the case of shared pmds. fault mutex prevents | |
433 | * races with other faulting threads. | |
60d4d2d2 | 434 | */ |
c0d0381a | 435 | idx = linear_page_index(dst_vma, dst_addr); |
3a47c54f | 436 | mapping = dst_vma->vm_file->f_mapping; |
188b04a7 | 437 | hash = hugetlb_fault_mutex_hash(mapping, idx); |
60d4d2d2 | 438 | mutex_lock(&hugetlb_fault_mutex_table[hash]); |
40549ba8 | 439 | hugetlb_vma_lock_read(dst_vma); |
60d4d2d2 MK |
440 | |
441 | err = -ENOMEM; | |
aec44e0f | 442 | dst_pte = huge_pte_alloc(dst_mm, dst_vma, dst_addr, vma_hpagesize); |
60d4d2d2 | 443 | if (!dst_pte) { |
40549ba8 | 444 | hugetlb_vma_unlock_read(dst_vma); |
60d4d2d2 MK |
445 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); |
446 | goto out_unlock; | |
447 | } | |
448 | ||
d9712937 | 449 | if (!uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE) && |
6041c691 | 450 | !huge_pte_none_mostly(huge_ptep_get(dst_pte))) { |
f6191471 | 451 | err = -EEXIST; |
40549ba8 | 452 | hugetlb_vma_unlock_read(dst_vma); |
60d4d2d2 MK |
453 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); |
454 | goto out_unlock; | |
455 | } | |
456 | ||
d9712937 | 457 | err = hugetlb_mfill_atomic_pte(dst_pte, dst_vma, dst_addr, |
0169fd51 | 458 | src_addr, flags, &folio); |
60d4d2d2 | 459 | |
40549ba8 | 460 | hugetlb_vma_unlock_read(dst_vma); |
60d4d2d2 MK |
461 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); |
462 | ||
463 | cond_resched(); | |
464 | ||
9e368259 | 465 | if (unlikely(err == -ENOENT)) { |
d8ed45c5 | 466 | mmap_read_unlock(dst_mm); |
0169fd51 | 467 | BUG_ON(!folio); |
60d4d2d2 | 468 | |
0169fd51 | 469 | err = copy_folio_from_user(folio, |
e87340ca | 470 | (const void __user *)src_addr, true); |
60d4d2d2 MK |
471 | if (unlikely(err)) { |
472 | err = -EFAULT; | |
473 | goto out; | |
474 | } | |
d8ed45c5 | 475 | mmap_read_lock(dst_mm); |
60d4d2d2 MK |
476 | |
477 | dst_vma = NULL; | |
478 | goto retry; | |
479 | } else | |
0169fd51 | 480 | BUG_ON(folio); |
60d4d2d2 MK |
481 | |
482 | if (!err) { | |
483 | dst_addr += vma_hpagesize; | |
484 | src_addr += vma_hpagesize; | |
485 | copied += vma_hpagesize; | |
486 | ||
487 | if (fatal_signal_pending(current)) | |
488 | err = -EINTR; | |
489 | } | |
490 | if (err) | |
491 | break; | |
492 | } | |
493 | ||
494 | out_unlock: | |
d8ed45c5 | 495 | mmap_read_unlock(dst_mm); |
60d4d2d2 | 496 | out: |
0169fd51 Z |
497 | if (folio) |
498 | folio_put(folio); | |
60d4d2d2 MK |
499 | BUG_ON(copied < 0); |
500 | BUG_ON(err > 0); | |
501 | BUG_ON(!copied && !err); | |
502 | return copied ? copied : err; | |
503 | } | |
504 | #else /* !CONFIG_HUGETLB_PAGE */ | |
505 | /* fail at build time if gcc attempts to use this */ | |
61c50040 AR |
506 | extern ssize_t mfill_atomic_hugetlb(struct vm_area_struct *dst_vma, |
507 | unsigned long dst_start, | |
508 | unsigned long src_start, | |
509 | unsigned long len, | |
d9712937 | 510 | uffd_flags_t flags); |
60d4d2d2 MK |
511 | #endif /* CONFIG_HUGETLB_PAGE */ |
512 | ||
61c50040 | 513 | static __always_inline ssize_t mfill_atomic_pte(pmd_t *dst_pmd, |
3217d3c7 MR |
514 | struct vm_area_struct *dst_vma, |
515 | unsigned long dst_addr, | |
516 | unsigned long src_addr, | |
d9712937 | 517 | uffd_flags_t flags, |
d7be6d7e | 518 | struct folio **foliop) |
3217d3c7 MR |
519 | { |
520 | ssize_t err; | |
521 | ||
d9712937 | 522 | if (uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE)) { |
61c50040 | 523 | return mfill_atomic_pte_continue(dst_pmd, dst_vma, |
d9712937 | 524 | dst_addr, flags); |
fc71884a AR |
525 | } else if (uffd_flags_mode_is(flags, MFILL_ATOMIC_POISON)) { |
526 | return mfill_atomic_pte_poison(dst_pmd, dst_vma, | |
527 | dst_addr, flags); | |
15313257 AR |
528 | } |
529 | ||
5b51072e AA |
530 | /* |
531 | * The normal page fault path for a shmem will invoke the | |
532 | * fault, fill the hole in the file and COW it right away. The | |
533 | * result generates plain anonymous memory. So when we are | |
534 | * asked to fill an hole in a MAP_PRIVATE shmem mapping, we'll | |
535 | * generate anonymous memory directly without actually filling | |
536 | * the hole. For the MAP_PRIVATE case the robustness check | |
537 | * only happens in the pagetable (to verify it's still none) | |
538 | * and not in the radix tree. | |
539 | */ | |
540 | if (!(dst_vma->vm_flags & VM_SHARED)) { | |
d9712937 | 541 | if (uffd_flags_mode_is(flags, MFILL_ATOMIC_COPY)) |
61c50040 | 542 | err = mfill_atomic_pte_copy(dst_pmd, dst_vma, |
d9712937 | 543 | dst_addr, src_addr, |
d7be6d7e | 544 | flags, foliop); |
3217d3c7 | 545 | else |
61c50040 | 546 | err = mfill_atomic_pte_zeropage(dst_pmd, |
3217d3c7 MR |
547 | dst_vma, dst_addr); |
548 | } else { | |
61c50040 | 549 | err = shmem_mfill_atomic_pte(dst_pmd, dst_vma, |
15313257 | 550 | dst_addr, src_addr, |
d7be6d7e | 551 | flags, foliop); |
3217d3c7 MR |
552 | } |
553 | ||
554 | return err; | |
555 | } | |
556 | ||
a734991c AR |
557 | static __always_inline ssize_t mfill_atomic(struct mm_struct *dst_mm, |
558 | unsigned long dst_start, | |
559 | unsigned long src_start, | |
560 | unsigned long len, | |
a734991c | 561 | atomic_t *mmap_changing, |
d9712937 | 562 | uffd_flags_t flags) |
c1a4de99 AA |
563 | { |
564 | struct vm_area_struct *dst_vma; | |
565 | ssize_t err; | |
566 | pmd_t *dst_pmd; | |
567 | unsigned long src_addr, dst_addr; | |
b6ebaedb | 568 | long copied; |
d7be6d7e | 569 | struct folio *folio; |
c1a4de99 AA |
570 | |
571 | /* | |
572 | * Sanitize the command parameters: | |
573 | */ | |
574 | BUG_ON(dst_start & ~PAGE_MASK); | |
575 | BUG_ON(len & ~PAGE_MASK); | |
576 | ||
577 | /* Does the address range wrap, or is the span zero-sized? */ | |
578 | BUG_ON(src_start + len <= src_start); | |
579 | BUG_ON(dst_start + len <= dst_start); | |
580 | ||
b6ebaedb AA |
581 | src_addr = src_start; |
582 | dst_addr = dst_start; | |
583 | copied = 0; | |
d7be6d7e | 584 | folio = NULL; |
b6ebaedb | 585 | retry: |
d8ed45c5 | 586 | mmap_read_lock(dst_mm); |
c1a4de99 | 587 | |
df2cc96e MR |
588 | /* |
589 | * If memory mappings are changing because of non-cooperative | |
590 | * operation (e.g. mremap) running in parallel, bail out and | |
591 | * request the user to retry later | |
592 | */ | |
593 | err = -EAGAIN; | |
a759a909 | 594 | if (mmap_changing && atomic_read(mmap_changing)) |
df2cc96e MR |
595 | goto out_unlock; |
596 | ||
c1a4de99 AA |
597 | /* |
598 | * Make sure the vma is not shared, that the dst range is | |
599 | * both valid and fully within a single existing vma. | |
600 | */ | |
27d02568 | 601 | err = -ENOENT; |
643aa36e | 602 | dst_vma = find_dst_vma(dst_mm, dst_start, len); |
26071ced MR |
603 | if (!dst_vma) |
604 | goto out_unlock; | |
c1a4de99 | 605 | |
27d02568 MR |
606 | err = -EINVAL; |
607 | /* | |
608 | * shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but | |
609 | * it will overwrite vm_ops, so vma_is_anonymous must return false. | |
610 | */ | |
611 | if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) && | |
612 | dst_vma->vm_flags & VM_SHARED)) | |
613 | goto out_unlock; | |
614 | ||
72981e0e AA |
615 | /* |
616 | * validate 'mode' now that we know the dst_vma: don't allow | |
617 | * a wrprotect copy if the userfaultfd didn't register as WP. | |
618 | */ | |
d9712937 | 619 | if ((flags & MFILL_ATOMIC_WP) && !(dst_vma->vm_flags & VM_UFFD_WP)) |
72981e0e AA |
620 | goto out_unlock; |
621 | ||
60d4d2d2 MK |
622 | /* |
623 | * If this is a HUGETLB vma, pass off to appropriate routine | |
624 | */ | |
625 | if (is_vm_hugetlb_page(dst_vma)) | |
61c50040 | 626 | return mfill_atomic_hugetlb(dst_vma, dst_start, |
d9712937 | 627 | src_start, len, flags); |
60d4d2d2 | 628 | |
26071ced | 629 | if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) |
b6ebaedb | 630 | goto out_unlock; |
d9712937 AR |
631 | if (!vma_is_shmem(dst_vma) && |
632 | uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE)) | |
f6191471 | 633 | goto out_unlock; |
c1a4de99 AA |
634 | |
635 | /* | |
636 | * Ensure the dst_vma has a anon_vma or this page | |
637 | * would get a NULL anon_vma when moved in the | |
638 | * dst_vma. | |
639 | */ | |
640 | err = -ENOMEM; | |
5b51072e AA |
641 | if (!(dst_vma->vm_flags & VM_SHARED) && |
642 | unlikely(anon_vma_prepare(dst_vma))) | |
b6ebaedb | 643 | goto out_unlock; |
c1a4de99 | 644 | |
b6ebaedb | 645 | while (src_addr < src_start + len) { |
c1a4de99 | 646 | pmd_t dst_pmdval; |
b6ebaedb | 647 | |
c1a4de99 | 648 | BUG_ON(dst_addr >= dst_start + len); |
b6ebaedb | 649 | |
c1a4de99 AA |
650 | dst_pmd = mm_alloc_pmd(dst_mm, dst_addr); |
651 | if (unlikely(!dst_pmd)) { | |
652 | err = -ENOMEM; | |
653 | break; | |
654 | } | |
655 | ||
dab6e717 | 656 | dst_pmdval = pmdp_get_lockless(dst_pmd); |
c1a4de99 AA |
657 | /* |
658 | * If the dst_pmd is mapped as THP don't | |
659 | * override it and just be strict. | |
660 | */ | |
661 | if (unlikely(pmd_trans_huge(dst_pmdval))) { | |
662 | err = -EEXIST; | |
663 | break; | |
664 | } | |
665 | if (unlikely(pmd_none(dst_pmdval)) && | |
4cf58924 | 666 | unlikely(__pte_alloc(dst_mm, dst_pmd))) { |
c1a4de99 AA |
667 | err = -ENOMEM; |
668 | break; | |
669 | } | |
670 | /* If an huge pmd materialized from under us fail */ | |
671 | if (unlikely(pmd_trans_huge(*dst_pmd))) { | |
672 | err = -EFAULT; | |
673 | break; | |
674 | } | |
675 | ||
676 | BUG_ON(pmd_none(*dst_pmd)); | |
677 | BUG_ON(pmd_trans_huge(*dst_pmd)); | |
678 | ||
61c50040 | 679 | err = mfill_atomic_pte(dst_pmd, dst_vma, dst_addr, |
d7be6d7e | 680 | src_addr, flags, &folio); |
c1a4de99 AA |
681 | cond_resched(); |
682 | ||
9e368259 | 683 | if (unlikely(err == -ENOENT)) { |
d7be6d7e | 684 | void *kaddr; |
b6ebaedb | 685 | |
d8ed45c5 | 686 | mmap_read_unlock(dst_mm); |
d7be6d7e | 687 | BUG_ON(!folio); |
b6ebaedb | 688 | |
d7be6d7e Z |
689 | kaddr = kmap_local_folio(folio, 0); |
690 | err = copy_from_user(kaddr, | |
b6ebaedb AA |
691 | (const void __user *) src_addr, |
692 | PAGE_SIZE); | |
d7be6d7e | 693 | kunmap_local(kaddr); |
b6ebaedb AA |
694 | if (unlikely(err)) { |
695 | err = -EFAULT; | |
696 | goto out; | |
697 | } | |
d7be6d7e | 698 | flush_dcache_folio(folio); |
b6ebaedb AA |
699 | goto retry; |
700 | } else | |
d7be6d7e | 701 | BUG_ON(folio); |
b6ebaedb | 702 | |
c1a4de99 AA |
703 | if (!err) { |
704 | dst_addr += PAGE_SIZE; | |
705 | src_addr += PAGE_SIZE; | |
706 | copied += PAGE_SIZE; | |
707 | ||
708 | if (fatal_signal_pending(current)) | |
709 | err = -EINTR; | |
710 | } | |
711 | if (err) | |
712 | break; | |
713 | } | |
714 | ||
b6ebaedb | 715 | out_unlock: |
d8ed45c5 | 716 | mmap_read_unlock(dst_mm); |
b6ebaedb | 717 | out: |
d7be6d7e Z |
718 | if (folio) |
719 | folio_put(folio); | |
c1a4de99 AA |
720 | BUG_ON(copied < 0); |
721 | BUG_ON(err > 0); | |
722 | BUG_ON(!copied && !err); | |
723 | return copied ? copied : err; | |
724 | } | |
725 | ||
a734991c AR |
726 | ssize_t mfill_atomic_copy(struct mm_struct *dst_mm, unsigned long dst_start, |
727 | unsigned long src_start, unsigned long len, | |
d9712937 | 728 | atomic_t *mmap_changing, uffd_flags_t flags) |
c1a4de99 | 729 | { |
d9712937 AR |
730 | return mfill_atomic(dst_mm, dst_start, src_start, len, mmap_changing, |
731 | uffd_flags_set_mode(flags, MFILL_ATOMIC_COPY)); | |
c1a4de99 AA |
732 | } |
733 | ||
a734991c AR |
734 | ssize_t mfill_atomic_zeropage(struct mm_struct *dst_mm, unsigned long start, |
735 | unsigned long len, atomic_t *mmap_changing) | |
c1a4de99 | 736 | { |
d9712937 AR |
737 | return mfill_atomic(dst_mm, start, 0, len, mmap_changing, |
738 | uffd_flags_set_mode(0, MFILL_ATOMIC_ZEROPAGE)); | |
f6191471 AR |
739 | } |
740 | ||
a734991c | 741 | ssize_t mfill_atomic_continue(struct mm_struct *dst_mm, unsigned long start, |
02891844 AR |
742 | unsigned long len, atomic_t *mmap_changing, |
743 | uffd_flags_t flags) | |
f6191471 | 744 | { |
d9712937 | 745 | return mfill_atomic(dst_mm, start, 0, len, mmap_changing, |
02891844 | 746 | uffd_flags_set_mode(flags, MFILL_ATOMIC_CONTINUE)); |
c1a4de99 | 747 | } |
ffd05793 | 748 | |
fc71884a AR |
749 | ssize_t mfill_atomic_poison(struct mm_struct *dst_mm, unsigned long start, |
750 | unsigned long len, atomic_t *mmap_changing, | |
751 | uffd_flags_t flags) | |
752 | { | |
753 | return mfill_atomic(dst_mm, start, 0, len, mmap_changing, | |
754 | uffd_flags_set_mode(flags, MFILL_ATOMIC_POISON)); | |
755 | } | |
756 | ||
61c50040 | 757 | long uffd_wp_range(struct vm_area_struct *dst_vma, |
f369b07c PX |
758 | unsigned long start, unsigned long len, bool enable_wp) |
759 | { | |
931298e1 | 760 | unsigned int mm_cp_flags; |
f369b07c | 761 | struct mmu_gather tlb; |
d1751118 | 762 | long ret; |
f369b07c | 763 | |
a1b92a3f MUA |
764 | VM_WARN_ONCE(start < dst_vma->vm_start || start + len > dst_vma->vm_end, |
765 | "The address range exceeds VMA boundary.\n"); | |
f369b07c | 766 | if (enable_wp) |
931298e1 | 767 | mm_cp_flags = MM_CP_UFFD_WP; |
f369b07c | 768 | else |
931298e1 | 769 | mm_cp_flags = MM_CP_UFFD_WP_RESOLVE; |
f369b07c | 770 | |
931298e1 DH |
771 | /* |
772 | * vma->vm_page_prot already reflects that uffd-wp is enabled for this | |
773 | * VMA (see userfaultfd_set_vm_flags()) and that all PTEs are supposed | |
774 | * to be write-protected as default whenever protection changes. | |
775 | * Try upgrading write permissions manually. | |
776 | */ | |
777 | if (!enable_wp && vma_wants_manual_pte_write_upgrade(dst_vma)) | |
778 | mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; | |
61c50040 | 779 | tlb_gather_mmu(&tlb, dst_vma->vm_mm); |
d1751118 | 780 | ret = change_protection(&tlb, dst_vma, start, start + len, mm_cp_flags); |
f369b07c | 781 | tlb_finish_mmu(&tlb); |
d1751118 PX |
782 | |
783 | return ret; | |
f369b07c PX |
784 | } |
785 | ||
ffd05793 | 786 | int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, |
a759a909 NA |
787 | unsigned long len, bool enable_wp, |
788 | atomic_t *mmap_changing) | |
ffd05793 | 789 | { |
a1b92a3f MUA |
790 | unsigned long end = start + len; |
791 | unsigned long _start, _end; | |
ffd05793 | 792 | struct vm_area_struct *dst_vma; |
5a90d5a1 | 793 | unsigned long page_mask; |
d1751118 | 794 | long err; |
a1b92a3f | 795 | VMA_ITERATOR(vmi, dst_mm, start); |
ffd05793 SL |
796 | |
797 | /* | |
798 | * Sanitize the command parameters: | |
799 | */ | |
800 | BUG_ON(start & ~PAGE_MASK); | |
801 | BUG_ON(len & ~PAGE_MASK); | |
802 | ||
803 | /* Does the address range wrap, or is the span zero-sized? */ | |
804 | BUG_ON(start + len <= start); | |
805 | ||
d8ed45c5 | 806 | mmap_read_lock(dst_mm); |
ffd05793 SL |
807 | |
808 | /* | |
809 | * If memory mappings are changing because of non-cooperative | |
810 | * operation (e.g. mremap) running in parallel, bail out and | |
811 | * request the user to retry later | |
812 | */ | |
813 | err = -EAGAIN; | |
a759a909 | 814 | if (mmap_changing && atomic_read(mmap_changing)) |
ffd05793 SL |
815 | goto out_unlock; |
816 | ||
817 | err = -ENOENT; | |
a1b92a3f | 818 | for_each_vma_range(vmi, dst_vma, end) { |
b1f9e876 | 819 | |
a1b92a3f MUA |
820 | if (!userfaultfd_wp(dst_vma)) { |
821 | err = -ENOENT; | |
822 | break; | |
823 | } | |
ffd05793 | 824 | |
a1b92a3f MUA |
825 | if (is_vm_hugetlb_page(dst_vma)) { |
826 | err = -EINVAL; | |
827 | page_mask = vma_kernel_pagesize(dst_vma) - 1; | |
828 | if ((start & page_mask) || (len & page_mask)) | |
829 | break; | |
830 | } | |
5a90d5a1 | 831 | |
a1b92a3f MUA |
832 | _start = max(dst_vma->vm_start, start); |
833 | _end = min(dst_vma->vm_end, end); | |
d1751118 | 834 | |
61c50040 | 835 | err = uffd_wp_range(dst_vma, _start, _end - _start, enable_wp); |
ffd05793 | 836 | |
a1b92a3f MUA |
837 | /* Return 0 on success, <0 on failures */ |
838 | if (err < 0) | |
839 | break; | |
840 | err = 0; | |
841 | } | |
ffd05793 | 842 | out_unlock: |
d8ed45c5 | 843 | mmap_read_unlock(dst_mm); |
ffd05793 SL |
844 | return err; |
845 | } |