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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
7999096f | 2 | #include <crypto/hash.h> |
4f18cd31 | 3 | #include <linux/export.h> |
2f8b5444 | 4 | #include <linux/bvec.h> |
4d0e9df5 | 5 | #include <linux/fault-inject-usercopy.h> |
4f18cd31 AV |
6 | #include <linux/uio.h> |
7 | #include <linux/pagemap.h> | |
28961998 | 8 | #include <linux/highmem.h> |
91f79c43 AV |
9 | #include <linux/slab.h> |
10 | #include <linux/vmalloc.h> | |
241699cd | 11 | #include <linux/splice.h> |
bfdc5970 | 12 | #include <linux/compat.h> |
a604ec7e | 13 | #include <net/checksum.h> |
d05f4435 | 14 | #include <linux/scatterlist.h> |
d0ef4c36 | 15 | #include <linux/instrumented.h> |
4f18cd31 | 16 | |
241699cd AV |
17 | #define PIPE_PARANOIA /* for now */ |
18 | ||
fcb14cb1 AV |
19 | /* covers ubuf and kbuf alike */ |
20 | #define iterate_buf(i, n, base, len, off, __p, STEP) { \ | |
21 | size_t __maybe_unused off = 0; \ | |
22 | len = n; \ | |
23 | base = __p + i->iov_offset; \ | |
24 | len -= (STEP); \ | |
25 | i->iov_offset += len; \ | |
26 | n = len; \ | |
27 | } | |
28 | ||
5c67aa90 | 29 | /* covers iovec and kvec alike */ |
a6e4ec7b | 30 | #define iterate_iovec(i, n, base, len, off, __p, STEP) { \ |
7baa5099 | 31 | size_t off = 0; \ |
a6e4ec7b | 32 | size_t skip = i->iov_offset; \ |
7a1bcb5d | 33 | do { \ |
7baa5099 AV |
34 | len = min(n, __p->iov_len - skip); \ |
35 | if (likely(len)) { \ | |
36 | base = __p->iov_base + skip; \ | |
37 | len -= (STEP); \ | |
38 | off += len; \ | |
39 | skip += len; \ | |
40 | n -= len; \ | |
7a1bcb5d AV |
41 | if (skip < __p->iov_len) \ |
42 | break; \ | |
43 | } \ | |
44 | __p++; \ | |
45 | skip = 0; \ | |
46 | } while (n); \ | |
a6e4ec7b | 47 | i->iov_offset = skip; \ |
7baa5099 | 48 | n = off; \ |
04a31165 AV |
49 | } |
50 | ||
a6e4ec7b | 51 | #define iterate_bvec(i, n, base, len, off, p, STEP) { \ |
7baa5099 | 52 | size_t off = 0; \ |
a6e4ec7b | 53 | unsigned skip = i->iov_offset; \ |
7491a2bf AV |
54 | while (n) { \ |
55 | unsigned offset = p->bv_offset + skip; \ | |
1b4fb5ff | 56 | unsigned left; \ |
21b56c84 AV |
57 | void *kaddr = kmap_local_page(p->bv_page + \ |
58 | offset / PAGE_SIZE); \ | |
7baa5099 | 59 | base = kaddr + offset % PAGE_SIZE; \ |
a6e4ec7b | 60 | len = min(min(n, (size_t)(p->bv_len - skip)), \ |
7491a2bf | 61 | (size_t)(PAGE_SIZE - offset % PAGE_SIZE)); \ |
1b4fb5ff | 62 | left = (STEP); \ |
21b56c84 | 63 | kunmap_local(kaddr); \ |
7baa5099 AV |
64 | len -= left; \ |
65 | off += len; \ | |
66 | skip += len; \ | |
7491a2bf AV |
67 | if (skip == p->bv_len) { \ |
68 | skip = 0; \ | |
69 | p++; \ | |
70 | } \ | |
7baa5099 | 71 | n -= len; \ |
1b4fb5ff AV |
72 | if (left) \ |
73 | break; \ | |
7491a2bf | 74 | } \ |
a6e4ec7b | 75 | i->iov_offset = skip; \ |
7baa5099 | 76 | n = off; \ |
04a31165 AV |
77 | } |
78 | ||
a6e4ec7b | 79 | #define iterate_xarray(i, n, base, len, __off, STEP) { \ |
1b4fb5ff | 80 | __label__ __out; \ |
622838f3 | 81 | size_t __off = 0; \ |
821979f5 | 82 | struct folio *folio; \ |
a6e4ec7b | 83 | loff_t start = i->xarray_start + i->iov_offset; \ |
4b179e9a | 84 | pgoff_t index = start / PAGE_SIZE; \ |
7ff50620 DH |
85 | XA_STATE(xas, i->xarray, index); \ |
86 | \ | |
821979f5 | 87 | len = PAGE_SIZE - offset_in_page(start); \ |
7baa5099 | 88 | rcu_read_lock(); \ |
821979f5 | 89 | xas_for_each(&xas, folio, ULONG_MAX) { \ |
7baa5099 | 90 | unsigned left; \ |
821979f5 MWO |
91 | size_t offset; \ |
92 | if (xas_retry(&xas, folio)) \ | |
7baa5099 | 93 | continue; \ |
821979f5 | 94 | if (WARN_ON(xa_is_value(folio))) \ |
7baa5099 | 95 | break; \ |
821979f5 | 96 | if (WARN_ON(folio_test_hugetlb(folio))) \ |
7baa5099 | 97 | break; \ |
821979f5 MWO |
98 | offset = offset_in_folio(folio, start + __off); \ |
99 | while (offset < folio_size(folio)) { \ | |
100 | base = kmap_local_folio(folio, offset); \ | |
7baa5099 AV |
101 | len = min(n, len); \ |
102 | left = (STEP); \ | |
821979f5 | 103 | kunmap_local(base); \ |
7baa5099 AV |
104 | len -= left; \ |
105 | __off += len; \ | |
106 | n -= len; \ | |
107 | if (left || n == 0) \ | |
108 | goto __out; \ | |
821979f5 MWO |
109 | offset += len; \ |
110 | len = PAGE_SIZE; \ | |
7baa5099 | 111 | } \ |
7ff50620 | 112 | } \ |
1b4fb5ff | 113 | __out: \ |
7ff50620 | 114 | rcu_read_unlock(); \ |
821979f5 | 115 | i->iov_offset += __off; \ |
622838f3 | 116 | n = __off; \ |
7ff50620 DH |
117 | } |
118 | ||
7baa5099 | 119 | #define __iterate_and_advance(i, n, base, len, off, I, K) { \ |
dd254f5a AV |
120 | if (unlikely(i->count < n)) \ |
121 | n = i->count; \ | |
f5da8354 | 122 | if (likely(n)) { \ |
fcb14cb1 AV |
123 | if (likely(iter_is_ubuf(i))) { \ |
124 | void __user *base; \ | |
125 | size_t len; \ | |
126 | iterate_buf(i, n, base, len, off, \ | |
127 | i->ubuf, (I)) \ | |
128 | } else if (likely(iter_is_iovec(i))) { \ | |
5c67aa90 | 129 | const struct iovec *iov = i->iov; \ |
7baa5099 AV |
130 | void __user *base; \ |
131 | size_t len; \ | |
132 | iterate_iovec(i, n, base, len, off, \ | |
a6e4ec7b | 133 | iov, (I)) \ |
28f38db7 AV |
134 | i->nr_segs -= iov - i->iov; \ |
135 | i->iov = iov; \ | |
136 | } else if (iov_iter_is_bvec(i)) { \ | |
1bdc76ae | 137 | const struct bio_vec *bvec = i->bvec; \ |
7baa5099 AV |
138 | void *base; \ |
139 | size_t len; \ | |
140 | iterate_bvec(i, n, base, len, off, \ | |
a6e4ec7b | 141 | bvec, (K)) \ |
7491a2bf AV |
142 | i->nr_segs -= bvec - i->bvec; \ |
143 | i->bvec = bvec; \ | |
28f38db7 | 144 | } else if (iov_iter_is_kvec(i)) { \ |
5c67aa90 | 145 | const struct kvec *kvec = i->kvec; \ |
7baa5099 AV |
146 | void *base; \ |
147 | size_t len; \ | |
148 | iterate_iovec(i, n, base, len, off, \ | |
a6e4ec7b | 149 | kvec, (K)) \ |
dd254f5a AV |
150 | i->nr_segs -= kvec - i->kvec; \ |
151 | i->kvec = kvec; \ | |
28f38db7 | 152 | } else if (iov_iter_is_xarray(i)) { \ |
7baa5099 AV |
153 | void *base; \ |
154 | size_t len; \ | |
155 | iterate_xarray(i, n, base, len, off, \ | |
a6e4ec7b | 156 | (K)) \ |
7ce2a91e | 157 | } \ |
dd254f5a | 158 | i->count -= n; \ |
7ce2a91e | 159 | } \ |
7ce2a91e | 160 | } |
7baa5099 AV |
161 | #define iterate_and_advance(i, n, base, len, off, I, K) \ |
162 | __iterate_and_advance(i, n, base, len, off, I, ((void)(K),0)) | |
7ce2a91e | 163 | |
09fc68dc AV |
164 | static int copyout(void __user *to, const void *from, size_t n) |
165 | { | |
4d0e9df5 AL |
166 | if (should_fail_usercopy()) |
167 | return n; | |
96d4f267 | 168 | if (access_ok(to, n)) { |
d0ef4c36 | 169 | instrument_copy_to_user(to, from, n); |
09fc68dc AV |
170 | n = raw_copy_to_user(to, from, n); |
171 | } | |
172 | return n; | |
173 | } | |
174 | ||
175 | static int copyin(void *to, const void __user *from, size_t n) | |
176 | { | |
4d0e9df5 AL |
177 | if (should_fail_usercopy()) |
178 | return n; | |
96d4f267 | 179 | if (access_ok(from, n)) { |
d0ef4c36 | 180 | instrument_copy_from_user(to, from, n); |
09fc68dc AV |
181 | n = raw_copy_from_user(to, from, n); |
182 | } | |
183 | return n; | |
184 | } | |
185 | ||
2dcedb2a AV |
186 | static inline struct pipe_buffer *pipe_buf(const struct pipe_inode_info *pipe, |
187 | unsigned int slot) | |
188 | { | |
189 | return &pipe->bufs[slot & (pipe->ring_size - 1)]; | |
190 | } | |
191 | ||
241699cd AV |
192 | #ifdef PIPE_PARANOIA |
193 | static bool sanity(const struct iov_iter *i) | |
194 | { | |
195 | struct pipe_inode_info *pipe = i->pipe; | |
8cefc107 DH |
196 | unsigned int p_head = pipe->head; |
197 | unsigned int p_tail = pipe->tail; | |
8cefc107 DH |
198 | unsigned int p_occupancy = pipe_occupancy(p_head, p_tail); |
199 | unsigned int i_head = i->head; | |
200 | unsigned int idx; | |
201 | ||
241699cd AV |
202 | if (i->iov_offset) { |
203 | struct pipe_buffer *p; | |
8cefc107 | 204 | if (unlikely(p_occupancy == 0)) |
241699cd | 205 | goto Bad; // pipe must be non-empty |
8cefc107 | 206 | if (unlikely(i_head != p_head - 1)) |
241699cd AV |
207 | goto Bad; // must be at the last buffer... |
208 | ||
2dcedb2a | 209 | p = pipe_buf(pipe, i_head); |
241699cd AV |
210 | if (unlikely(p->offset + p->len != i->iov_offset)) |
211 | goto Bad; // ... at the end of segment | |
212 | } else { | |
8cefc107 | 213 | if (i_head != p_head) |
241699cd AV |
214 | goto Bad; // must be right after the last buffer |
215 | } | |
216 | return true; | |
217 | Bad: | |
8cefc107 DH |
218 | printk(KERN_ERR "idx = %d, offset = %zd\n", i_head, i->iov_offset); |
219 | printk(KERN_ERR "head = %d, tail = %d, buffers = %d\n", | |
220 | p_head, p_tail, pipe->ring_size); | |
221 | for (idx = 0; idx < pipe->ring_size; idx++) | |
241699cd AV |
222 | printk(KERN_ERR "[%p %p %d %d]\n", |
223 | pipe->bufs[idx].ops, | |
224 | pipe->bufs[idx].page, | |
225 | pipe->bufs[idx].offset, | |
226 | pipe->bufs[idx].len); | |
227 | WARN_ON(1); | |
228 | return false; | |
229 | } | |
230 | #else | |
231 | #define sanity(i) true | |
232 | #endif | |
233 | ||
47b7fcae AV |
234 | static struct page *push_anon(struct pipe_inode_info *pipe, unsigned size) |
235 | { | |
236 | struct page *page = alloc_page(GFP_USER); | |
237 | if (page) { | |
238 | struct pipe_buffer *buf = pipe_buf(pipe, pipe->head++); | |
239 | *buf = (struct pipe_buffer) { | |
240 | .ops = &default_pipe_buf_ops, | |
241 | .page = page, | |
242 | .offset = 0, | |
243 | .len = size | |
244 | }; | |
245 | } | |
246 | return page; | |
247 | } | |
248 | ||
249 | static void push_page(struct pipe_inode_info *pipe, struct page *page, | |
250 | unsigned int offset, unsigned int size) | |
251 | { | |
252 | struct pipe_buffer *buf = pipe_buf(pipe, pipe->head++); | |
253 | *buf = (struct pipe_buffer) { | |
254 | .ops = &page_cache_pipe_buf_ops, | |
255 | .page = page, | |
256 | .offset = offset, | |
257 | .len = size | |
258 | }; | |
259 | get_page(page); | |
260 | } | |
261 | ||
241699cd AV |
262 | static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes, |
263 | struct iov_iter *i) | |
264 | { | |
265 | struct pipe_inode_info *pipe = i->pipe; | |
47b7fcae | 266 | unsigned int head = pipe->head; |
241699cd AV |
267 | |
268 | if (unlikely(bytes > i->count)) | |
269 | bytes = i->count; | |
270 | ||
271 | if (unlikely(!bytes)) | |
272 | return 0; | |
273 | ||
274 | if (!sanity(i)) | |
275 | return 0; | |
276 | ||
47b7fcae AV |
277 | if (offset && i->iov_offset == offset) { // could we merge it? |
278 | struct pipe_buffer *buf = pipe_buf(pipe, head - 1); | |
279 | if (buf->page == page) { | |
241699cd AV |
280 | buf->len += bytes; |
281 | i->iov_offset += bytes; | |
47b7fcae AV |
282 | i->count -= bytes; |
283 | return bytes; | |
241699cd | 284 | } |
241699cd | 285 | } |
47b7fcae | 286 | if (pipe_full(pipe->head, pipe->tail, pipe->max_usage)) |
241699cd | 287 | return 0; |
8cefc107 | 288 | |
47b7fcae | 289 | push_page(pipe, page, offset, bytes); |
241699cd | 290 | i->iov_offset = offset + bytes; |
47b7fcae | 291 | i->head = head; |
241699cd AV |
292 | i->count -= bytes; |
293 | return bytes; | |
294 | } | |
295 | ||
171a0203 | 296 | /* |
a6294593 AG |
297 | * fault_in_iov_iter_readable - fault in iov iterator for reading |
298 | * @i: iterator | |
299 | * @size: maximum length | |
300 | * | |
171a0203 | 301 | * Fault in one or more iovecs of the given iov_iter, to a maximum length of |
a6294593 AG |
302 | * @size. For each iovec, fault in each page that constitutes the iovec. |
303 | * | |
304 | * Returns the number of bytes not faulted in (like copy_to_user() and | |
305 | * copy_from_user()). | |
171a0203 | 306 | * |
a6294593 | 307 | * Always returns 0 for non-userspace iterators. |
171a0203 | 308 | */ |
a6294593 | 309 | size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t size) |
171a0203 | 310 | { |
fcb14cb1 AV |
311 | if (iter_is_ubuf(i)) { |
312 | size_t n = min(size, iov_iter_count(i)); | |
313 | n -= fault_in_readable(i->ubuf + i->iov_offset, n); | |
314 | return size - n; | |
315 | } else if (iter_is_iovec(i)) { | |
a6294593 | 316 | size_t count = min(size, iov_iter_count(i)); |
8409a0d2 AV |
317 | const struct iovec *p; |
318 | size_t skip; | |
319 | ||
a6294593 AG |
320 | size -= count; |
321 | for (p = i->iov, skip = i->iov_offset; count; p++, skip = 0) { | |
322 | size_t len = min(count, p->iov_len - skip); | |
323 | size_t ret; | |
8409a0d2 AV |
324 | |
325 | if (unlikely(!len)) | |
326 | continue; | |
a6294593 AG |
327 | ret = fault_in_readable(p->iov_base + skip, len); |
328 | count -= len - ret; | |
329 | if (ret) | |
330 | break; | |
8409a0d2 | 331 | } |
a6294593 | 332 | return count + size; |
171a0203 AA |
333 | } |
334 | return 0; | |
335 | } | |
a6294593 | 336 | EXPORT_SYMBOL(fault_in_iov_iter_readable); |
171a0203 | 337 | |
cdd591fc AG |
338 | /* |
339 | * fault_in_iov_iter_writeable - fault in iov iterator for writing | |
340 | * @i: iterator | |
341 | * @size: maximum length | |
342 | * | |
343 | * Faults in the iterator using get_user_pages(), i.e., without triggering | |
344 | * hardware page faults. This is primarily useful when we already know that | |
345 | * some or all of the pages in @i aren't in memory. | |
346 | * | |
347 | * Returns the number of bytes not faulted in, like copy_to_user() and | |
348 | * copy_from_user(). | |
349 | * | |
350 | * Always returns 0 for non-user-space iterators. | |
351 | */ | |
352 | size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t size) | |
353 | { | |
fcb14cb1 AV |
354 | if (iter_is_ubuf(i)) { |
355 | size_t n = min(size, iov_iter_count(i)); | |
356 | n -= fault_in_safe_writeable(i->ubuf + i->iov_offset, n); | |
357 | return size - n; | |
358 | } else if (iter_is_iovec(i)) { | |
cdd591fc AG |
359 | size_t count = min(size, iov_iter_count(i)); |
360 | const struct iovec *p; | |
361 | size_t skip; | |
362 | ||
363 | size -= count; | |
364 | for (p = i->iov, skip = i->iov_offset; count; p++, skip = 0) { | |
365 | size_t len = min(count, p->iov_len - skip); | |
366 | size_t ret; | |
367 | ||
368 | if (unlikely(!len)) | |
369 | continue; | |
370 | ret = fault_in_safe_writeable(p->iov_base + skip, len); | |
371 | count -= len - ret; | |
372 | if (ret) | |
373 | break; | |
374 | } | |
375 | return count + size; | |
376 | } | |
377 | return 0; | |
378 | } | |
379 | EXPORT_SYMBOL(fault_in_iov_iter_writeable); | |
380 | ||
aa563d7b | 381 | void iov_iter_init(struct iov_iter *i, unsigned int direction, |
71d8e532 AV |
382 | const struct iovec *iov, unsigned long nr_segs, |
383 | size_t count) | |
384 | { | |
aa563d7b | 385 | WARN_ON(direction & ~(READ | WRITE)); |
8cd54c1c AV |
386 | *i = (struct iov_iter) { |
387 | .iter_type = ITER_IOVEC, | |
3337ab08 | 388 | .nofault = false, |
fcb14cb1 | 389 | .user_backed = true, |
8cd54c1c AV |
390 | .data_source = direction, |
391 | .iov = iov, | |
392 | .nr_segs = nr_segs, | |
393 | .iov_offset = 0, | |
394 | .count = count | |
395 | }; | |
71d8e532 AV |
396 | } |
397 | EXPORT_SYMBOL(iov_iter_init); | |
7b2c99d1 | 398 | |
241699cd AV |
399 | static inline bool allocated(struct pipe_buffer *buf) |
400 | { | |
401 | return buf->ops == &default_pipe_buf_ops; | |
402 | } | |
403 | ||
8cefc107 DH |
404 | static inline void data_start(const struct iov_iter *i, |
405 | unsigned int *iter_headp, size_t *offp) | |
241699cd | 406 | { |
8cefc107 | 407 | unsigned int iter_head = i->head; |
241699cd | 408 | size_t off = i->iov_offset; |
8cefc107 | 409 | |
2dcedb2a | 410 | if (off && (!allocated(pipe_buf(i->pipe, iter_head)) || |
8cefc107 DH |
411 | off == PAGE_SIZE)) { |
412 | iter_head++; | |
241699cd AV |
413 | off = 0; |
414 | } | |
8cefc107 | 415 | *iter_headp = iter_head; |
241699cd AV |
416 | *offp = off; |
417 | } | |
418 | ||
419 | static size_t push_pipe(struct iov_iter *i, size_t size, | |
8cefc107 | 420 | int *iter_headp, size_t *offp) |
241699cd AV |
421 | { |
422 | struct pipe_inode_info *pipe = i->pipe; | |
8cefc107 | 423 | unsigned int iter_head; |
241699cd | 424 | size_t off; |
241699cd AV |
425 | ssize_t left; |
426 | ||
427 | if (unlikely(size > i->count)) | |
428 | size = i->count; | |
429 | if (unlikely(!size)) | |
430 | return 0; | |
431 | ||
432 | left = size; | |
8cefc107 DH |
433 | data_start(i, &iter_head, &off); |
434 | *iter_headp = iter_head; | |
241699cd AV |
435 | *offp = off; |
436 | if (off) { | |
47b7fcae AV |
437 | struct pipe_buffer *buf = pipe_buf(pipe, iter_head); |
438 | ||
241699cd AV |
439 | left -= PAGE_SIZE - off; |
440 | if (left <= 0) { | |
47b7fcae | 441 | buf->len += size; |
241699cd AV |
442 | return size; |
443 | } | |
47b7fcae | 444 | buf->len = PAGE_SIZE; |
241699cd | 445 | } |
47b7fcae AV |
446 | while (!pipe_full(pipe->head, pipe->tail, pipe->max_usage)) { |
447 | struct page *page = push_anon(pipe, | |
448 | min_t(ssize_t, left, PAGE_SIZE)); | |
241699cd AV |
449 | if (!page) |
450 | break; | |
8cefc107 | 451 | |
47b7fcae AV |
452 | left -= PAGE_SIZE; |
453 | if (left <= 0) | |
241699cd | 454 | return size; |
241699cd AV |
455 | } |
456 | return size - left; | |
457 | } | |
458 | ||
459 | static size_t copy_pipe_to_iter(const void *addr, size_t bytes, | |
460 | struct iov_iter *i) | |
461 | { | |
462 | struct pipe_inode_info *pipe = i->pipe; | |
8cefc107 DH |
463 | unsigned int p_mask = pipe->ring_size - 1; |
464 | unsigned int i_head; | |
241699cd | 465 | size_t n, off; |
241699cd AV |
466 | |
467 | if (!sanity(i)) | |
468 | return 0; | |
469 | ||
8cefc107 | 470 | bytes = n = push_pipe(i, bytes, &i_head, &off); |
241699cd AV |
471 | if (unlikely(!n)) |
472 | return 0; | |
8cefc107 | 473 | do { |
241699cd | 474 | size_t chunk = min_t(size_t, n, PAGE_SIZE - off); |
8cefc107 DH |
475 | memcpy_to_page(pipe->bufs[i_head & p_mask].page, off, addr, chunk); |
476 | i->head = i_head; | |
241699cd AV |
477 | i->iov_offset = off + chunk; |
478 | n -= chunk; | |
479 | addr += chunk; | |
8cefc107 DH |
480 | off = 0; |
481 | i_head++; | |
482 | } while (n); | |
241699cd AV |
483 | i->count -= bytes; |
484 | return bytes; | |
485 | } | |
486 | ||
f9152895 AV |
487 | static __wsum csum_and_memcpy(void *to, const void *from, size_t len, |
488 | __wsum sum, size_t off) | |
489 | { | |
cc44c17b | 490 | __wsum next = csum_partial_copy_nocheck(from, to, len); |
f9152895 AV |
491 | return csum_block_add(sum, next, off); |
492 | } | |
493 | ||
78e1f386 | 494 | static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes, |
6852df12 | 495 | struct iov_iter *i, __wsum *sump) |
78e1f386 AV |
496 | { |
497 | struct pipe_inode_info *pipe = i->pipe; | |
8cefc107 | 498 | unsigned int p_mask = pipe->ring_size - 1; |
6852df12 AV |
499 | __wsum sum = *sump; |
500 | size_t off = 0; | |
8cefc107 | 501 | unsigned int i_head; |
6852df12 | 502 | size_t r; |
78e1f386 AV |
503 | |
504 | if (!sanity(i)) | |
505 | return 0; | |
506 | ||
6852df12 AV |
507 | bytes = push_pipe(i, bytes, &i_head, &r); |
508 | while (bytes) { | |
509 | size_t chunk = min_t(size_t, bytes, PAGE_SIZE - r); | |
2495bdcc | 510 | char *p = kmap_local_page(pipe->bufs[i_head & p_mask].page); |
6852df12 | 511 | sum = csum_and_memcpy(p + r, addr + off, chunk, sum, off); |
2495bdcc | 512 | kunmap_local(p); |
8cefc107 | 513 | i->head = i_head; |
78e1f386 | 514 | i->iov_offset = r + chunk; |
6852df12 | 515 | bytes -= chunk; |
78e1f386 | 516 | off += chunk; |
8cefc107 DH |
517 | r = 0; |
518 | i_head++; | |
6852df12 AV |
519 | } |
520 | *sump = sum; | |
521 | i->count -= off; | |
522 | return off; | |
78e1f386 AV |
523 | } |
524 | ||
aa28de27 | 525 | size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i) |
62a8067a | 526 | { |
00e23707 | 527 | if (unlikely(iov_iter_is_pipe(i))) |
241699cd | 528 | return copy_pipe_to_iter(addr, bytes, i); |
fcb14cb1 | 529 | if (user_backed_iter(i)) |
09fc68dc | 530 | might_fault(); |
7baa5099 AV |
531 | iterate_and_advance(i, bytes, base, len, off, |
532 | copyout(base, addr + off, len), | |
533 | memcpy(base, addr + off, len) | |
3d4d3e48 | 534 | ) |
62a8067a | 535 | |
3d4d3e48 | 536 | return bytes; |
c35e0248 | 537 | } |
aa28de27 | 538 | EXPORT_SYMBOL(_copy_to_iter); |
c35e0248 | 539 | |
ec6347bb DW |
540 | #ifdef CONFIG_ARCH_HAS_COPY_MC |
541 | static int copyout_mc(void __user *to, const void *from, size_t n) | |
8780356e | 542 | { |
96d4f267 | 543 | if (access_ok(to, n)) { |
d0ef4c36 | 544 | instrument_copy_to_user(to, from, n); |
ec6347bb | 545 | n = copy_mc_to_user((__force void *) to, from, n); |
8780356e DW |
546 | } |
547 | return n; | |
548 | } | |
549 | ||
ec6347bb | 550 | static size_t copy_mc_pipe_to_iter(const void *addr, size_t bytes, |
ca146f6f DW |
551 | struct iov_iter *i) |
552 | { | |
553 | struct pipe_inode_info *pipe = i->pipe; | |
8cefc107 DH |
554 | unsigned int p_mask = pipe->ring_size - 1; |
555 | unsigned int i_head; | |
c3497fd0 | 556 | unsigned int valid = pipe->head; |
ca146f6f | 557 | size_t n, off, xfer = 0; |
ca146f6f DW |
558 | |
559 | if (!sanity(i)) | |
560 | return 0; | |
561 | ||
2a510a74 AV |
562 | n = push_pipe(i, bytes, &i_head, &off); |
563 | while (n) { | |
ca146f6f | 564 | size_t chunk = min_t(size_t, n, PAGE_SIZE - off); |
2a510a74 | 565 | char *p = kmap_local_page(pipe->bufs[i_head & p_mask].page); |
ca146f6f | 566 | unsigned long rem; |
2a510a74 AV |
567 | rem = copy_mc_to_kernel(p + off, addr + xfer, chunk); |
568 | chunk -= rem; | |
569 | kunmap_local(p); | |
c3497fd0 AV |
570 | if (chunk) { |
571 | i->head = i_head; | |
572 | i->iov_offset = off + chunk; | |
573 | xfer += chunk; | |
574 | valid = i_head + 1; | |
575 | } | |
576 | if (rem) { | |
577 | pipe->bufs[i_head & p_mask].len -= rem; | |
578 | pipe_discard_from(pipe, valid); | |
ca146f6f | 579 | break; |
c3497fd0 | 580 | } |
ca146f6f | 581 | n -= chunk; |
8cefc107 DH |
582 | off = 0; |
583 | i_head++; | |
2a510a74 | 584 | } |
ca146f6f DW |
585 | i->count -= xfer; |
586 | return xfer; | |
587 | } | |
588 | ||
bf3eeb9b | 589 | /** |
ec6347bb | 590 | * _copy_mc_to_iter - copy to iter with source memory error exception handling |
bf3eeb9b DW |
591 | * @addr: source kernel address |
592 | * @bytes: total transfer length | |
44e55997 | 593 | * @i: destination iterator |
bf3eeb9b | 594 | * |
ec6347bb DW |
595 | * The pmem driver deploys this for the dax operation |
596 | * (dax_copy_to_iter()) for dax reads (bypass page-cache and the | |
597 | * block-layer). Upon #MC read(2) aborts and returns EIO or the bytes | |
598 | * successfully copied. | |
bf3eeb9b | 599 | * |
ec6347bb | 600 | * The main differences between this and typical _copy_to_iter(). |
bf3eeb9b DW |
601 | * |
602 | * * Typical tail/residue handling after a fault retries the copy | |
603 | * byte-by-byte until the fault happens again. Re-triggering machine | |
604 | * checks is potentially fatal so the implementation uses source | |
605 | * alignment and poison alignment assumptions to avoid re-triggering | |
606 | * hardware exceptions. | |
607 | * | |
608 | * * ITER_KVEC, ITER_PIPE, and ITER_BVEC can return short copies. | |
609 | * Compare to copy_to_iter() where only ITER_IOVEC attempts might return | |
610 | * a short copy. | |
44e55997 RD |
611 | * |
612 | * Return: number of bytes copied (may be %0) | |
bf3eeb9b | 613 | */ |
ec6347bb | 614 | size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i) |
8780356e | 615 | { |
00e23707 | 616 | if (unlikely(iov_iter_is_pipe(i))) |
ec6347bb | 617 | return copy_mc_pipe_to_iter(addr, bytes, i); |
fcb14cb1 | 618 | if (user_backed_iter(i)) |
8780356e | 619 | might_fault(); |
7baa5099 AV |
620 | __iterate_and_advance(i, bytes, base, len, off, |
621 | copyout_mc(base, addr + off, len), | |
622 | copy_mc_to_kernel(base, addr + off, len) | |
8780356e DW |
623 | ) |
624 | ||
625 | return bytes; | |
626 | } | |
ec6347bb DW |
627 | EXPORT_SYMBOL_GPL(_copy_mc_to_iter); |
628 | #endif /* CONFIG_ARCH_HAS_COPY_MC */ | |
8780356e | 629 | |
aa28de27 | 630 | size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i) |
c35e0248 | 631 | { |
00e23707 | 632 | if (unlikely(iov_iter_is_pipe(i))) { |
241699cd AV |
633 | WARN_ON(1); |
634 | return 0; | |
635 | } | |
fcb14cb1 | 636 | if (user_backed_iter(i)) |
09fc68dc | 637 | might_fault(); |
7baa5099 AV |
638 | iterate_and_advance(i, bytes, base, len, off, |
639 | copyin(addr + off, base, len), | |
640 | memcpy(addr + off, base, len) | |
0dbca9a4 AV |
641 | ) |
642 | ||
643 | return bytes; | |
c35e0248 | 644 | } |
aa28de27 | 645 | EXPORT_SYMBOL(_copy_from_iter); |
c35e0248 | 646 | |
aa28de27 | 647 | size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i) |
aa583096 | 648 | { |
00e23707 | 649 | if (unlikely(iov_iter_is_pipe(i))) { |
241699cd AV |
650 | WARN_ON(1); |
651 | return 0; | |
652 | } | |
7baa5099 AV |
653 | iterate_and_advance(i, bytes, base, len, off, |
654 | __copy_from_user_inatomic_nocache(addr + off, base, len), | |
655 | memcpy(addr + off, base, len) | |
aa583096 AV |
656 | ) |
657 | ||
658 | return bytes; | |
659 | } | |
aa28de27 | 660 | EXPORT_SYMBOL(_copy_from_iter_nocache); |
aa583096 | 661 | |
0aed55af | 662 | #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE |
abd08d7d DW |
663 | /** |
664 | * _copy_from_iter_flushcache - write destination through cpu cache | |
665 | * @addr: destination kernel address | |
666 | * @bytes: total transfer length | |
44e55997 | 667 | * @i: source iterator |
abd08d7d DW |
668 | * |
669 | * The pmem driver arranges for filesystem-dax to use this facility via | |
670 | * dax_copy_from_iter() for ensuring that writes to persistent memory | |
671 | * are flushed through the CPU cache. It is differentiated from | |
672 | * _copy_from_iter_nocache() in that guarantees all data is flushed for | |
673 | * all iterator types. The _copy_from_iter_nocache() only attempts to | |
674 | * bypass the cache for the ITER_IOVEC case, and on some archs may use | |
675 | * instructions that strand dirty-data in the cache. | |
44e55997 RD |
676 | * |
677 | * Return: number of bytes copied (may be %0) | |
abd08d7d | 678 | */ |
6a37e940 | 679 | size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i) |
0aed55af | 680 | { |
00e23707 | 681 | if (unlikely(iov_iter_is_pipe(i))) { |
0aed55af DW |
682 | WARN_ON(1); |
683 | return 0; | |
684 | } | |
7baa5099 AV |
685 | iterate_and_advance(i, bytes, base, len, off, |
686 | __copy_from_user_flushcache(addr + off, base, len), | |
687 | memcpy_flushcache(addr + off, base, len) | |
0aed55af DW |
688 | ) |
689 | ||
690 | return bytes; | |
691 | } | |
6a37e940 | 692 | EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache); |
0aed55af DW |
693 | #endif |
694 | ||
72e809ed AV |
695 | static inline bool page_copy_sane(struct page *page, size_t offset, size_t n) |
696 | { | |
6daef95b ED |
697 | struct page *head; |
698 | size_t v = n + offset; | |
699 | ||
700 | /* | |
701 | * The general case needs to access the page order in order | |
702 | * to compute the page size. | |
703 | * However, we mostly deal with order-0 pages and thus can | |
704 | * avoid a possible cache line miss for requests that fit all | |
705 | * page orders. | |
706 | */ | |
707 | if (n <= v && v <= PAGE_SIZE) | |
708 | return true; | |
709 | ||
710 | head = compound_head(page); | |
711 | v += (page - head) << PAGE_SHIFT; | |
a90bcb86 | 712 | |
a50b854e | 713 | if (likely(n <= v && v <= (page_size(head)))) |
72e809ed AV |
714 | return true; |
715 | WARN_ON(1); | |
716 | return false; | |
717 | } | |
cbbd26b8 | 718 | |
08aa6479 | 719 | static size_t __copy_page_to_iter(struct page *page, size_t offset, size_t bytes, |
62a8067a AV |
720 | struct iov_iter *i) |
721 | { | |
59bb69c6 AV |
722 | if (unlikely(iov_iter_is_pipe(i))) { |
723 | return copy_page_to_iter_pipe(page, offset, bytes, i); | |
724 | } else { | |
c1d4d6a9 AV |
725 | void *kaddr = kmap_local_page(page); |
726 | size_t wanted = _copy_to_iter(kaddr + offset, bytes, i); | |
727 | kunmap_local(kaddr); | |
d271524a | 728 | return wanted; |
28f38db7 | 729 | } |
62a8067a | 730 | } |
08aa6479 AV |
731 | |
732 | size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, | |
733 | struct iov_iter *i) | |
734 | { | |
735 | size_t res = 0; | |
736 | if (unlikely(!page_copy_sane(page, offset, bytes))) | |
737 | return 0; | |
738 | page += offset / PAGE_SIZE; // first subpage | |
739 | offset %= PAGE_SIZE; | |
740 | while (1) { | |
741 | size_t n = __copy_page_to_iter(page, offset, | |
742 | min(bytes, (size_t)PAGE_SIZE - offset), i); | |
743 | res += n; | |
744 | bytes -= n; | |
745 | if (!bytes || !n) | |
746 | break; | |
747 | offset += n; | |
748 | if (offset == PAGE_SIZE) { | |
749 | page++; | |
750 | offset = 0; | |
751 | } | |
752 | } | |
753 | return res; | |
754 | } | |
62a8067a AV |
755 | EXPORT_SYMBOL(copy_page_to_iter); |
756 | ||
757 | size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, | |
758 | struct iov_iter *i) | |
759 | { | |
59bb69c6 | 760 | if (page_copy_sane(page, offset, bytes)) { |
55ca375c | 761 | void *kaddr = kmap_local_page(page); |
aa28de27 | 762 | size_t wanted = _copy_from_iter(kaddr + offset, bytes, i); |
55ca375c | 763 | kunmap_local(kaddr); |
d271524a | 764 | return wanted; |
28f38db7 | 765 | } |
28f38db7 | 766 | return 0; |
62a8067a AV |
767 | } |
768 | EXPORT_SYMBOL(copy_page_from_iter); | |
769 | ||
241699cd AV |
770 | static size_t pipe_zero(size_t bytes, struct iov_iter *i) |
771 | { | |
772 | struct pipe_inode_info *pipe = i->pipe; | |
8cefc107 DH |
773 | unsigned int p_mask = pipe->ring_size - 1; |
774 | unsigned int i_head; | |
241699cd | 775 | size_t n, off; |
241699cd AV |
776 | |
777 | if (!sanity(i)) | |
778 | return 0; | |
779 | ||
8cefc107 | 780 | bytes = n = push_pipe(i, bytes, &i_head, &off); |
241699cd AV |
781 | if (unlikely(!n)) |
782 | return 0; | |
783 | ||
8cefc107 | 784 | do { |
241699cd | 785 | size_t chunk = min_t(size_t, n, PAGE_SIZE - off); |
893839fd AV |
786 | char *p = kmap_local_page(pipe->bufs[i_head & p_mask].page); |
787 | memset(p + off, 0, chunk); | |
788 | kunmap_local(p); | |
8cefc107 | 789 | i->head = i_head; |
241699cd AV |
790 | i->iov_offset = off + chunk; |
791 | n -= chunk; | |
8cefc107 DH |
792 | off = 0; |
793 | i_head++; | |
794 | } while (n); | |
241699cd AV |
795 | i->count -= bytes; |
796 | return bytes; | |
797 | } | |
798 | ||
c35e0248 MW |
799 | size_t iov_iter_zero(size_t bytes, struct iov_iter *i) |
800 | { | |
00e23707 | 801 | if (unlikely(iov_iter_is_pipe(i))) |
241699cd | 802 | return pipe_zero(bytes, i); |
7baa5099 AV |
803 | iterate_and_advance(i, bytes, base, len, count, |
804 | clear_user(base, len), | |
805 | memset(base, 0, len) | |
8442fa46 AV |
806 | ) |
807 | ||
808 | return bytes; | |
c35e0248 MW |
809 | } |
810 | EXPORT_SYMBOL(iov_iter_zero); | |
811 | ||
f0b65f39 AV |
812 | size_t copy_page_from_iter_atomic(struct page *page, unsigned offset, size_t bytes, |
813 | struct iov_iter *i) | |
62a8067a | 814 | { |
04a31165 | 815 | char *kaddr = kmap_atomic(page), *p = kaddr + offset; |
72e809ed AV |
816 | if (unlikely(!page_copy_sane(page, offset, bytes))) { |
817 | kunmap_atomic(kaddr); | |
818 | return 0; | |
819 | } | |
9ea9ce04 | 820 | if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { |
241699cd AV |
821 | kunmap_atomic(kaddr); |
822 | WARN_ON(1); | |
823 | return 0; | |
824 | } | |
7baa5099 AV |
825 | iterate_and_advance(i, bytes, base, len, off, |
826 | copyin(p + off, base, len), | |
827 | memcpy(p + off, base, len) | |
04a31165 AV |
828 | ) |
829 | kunmap_atomic(kaddr); | |
830 | return bytes; | |
62a8067a | 831 | } |
f0b65f39 | 832 | EXPORT_SYMBOL(copy_page_from_iter_atomic); |
62a8067a | 833 | |
b9dc6f65 AV |
834 | static inline void pipe_truncate(struct iov_iter *i) |
835 | { | |
836 | struct pipe_inode_info *pipe = i->pipe; | |
8cefc107 DH |
837 | unsigned int p_tail = pipe->tail; |
838 | unsigned int p_head = pipe->head; | |
839 | unsigned int p_mask = pipe->ring_size - 1; | |
840 | ||
841 | if (!pipe_empty(p_head, p_tail)) { | |
842 | struct pipe_buffer *buf; | |
843 | unsigned int i_head = i->head; | |
b9dc6f65 | 844 | size_t off = i->iov_offset; |
8cefc107 | 845 | |
b9dc6f65 | 846 | if (off) { |
8cefc107 DH |
847 | buf = &pipe->bufs[i_head & p_mask]; |
848 | buf->len = off - buf->offset; | |
849 | i_head++; | |
b9dc6f65 | 850 | } |
8cefc107 DH |
851 | while (p_head != i_head) { |
852 | p_head--; | |
853 | pipe_buf_release(pipe, &pipe->bufs[p_head & p_mask]); | |
b9dc6f65 | 854 | } |
8cefc107 DH |
855 | |
856 | pipe->head = p_head; | |
b9dc6f65 AV |
857 | } |
858 | } | |
859 | ||
241699cd AV |
860 | static void pipe_advance(struct iov_iter *i, size_t size) |
861 | { | |
862 | struct pipe_inode_info *pipe = i->pipe; | |
241699cd | 863 | if (size) { |
b9dc6f65 | 864 | struct pipe_buffer *buf; |
8cefc107 DH |
865 | unsigned int p_mask = pipe->ring_size - 1; |
866 | unsigned int i_head = i->head; | |
b9dc6f65 | 867 | size_t off = i->iov_offset, left = size; |
8cefc107 | 868 | |
241699cd | 869 | if (off) /* make it relative to the beginning of buffer */ |
8cefc107 | 870 | left += off - pipe->bufs[i_head & p_mask].offset; |
241699cd | 871 | while (1) { |
8cefc107 | 872 | buf = &pipe->bufs[i_head & p_mask]; |
b9dc6f65 | 873 | if (left <= buf->len) |
241699cd | 874 | break; |
b9dc6f65 | 875 | left -= buf->len; |
8cefc107 | 876 | i_head++; |
241699cd | 877 | } |
8cefc107 | 878 | i->head = i_head; |
b9dc6f65 | 879 | i->iov_offset = buf->offset + left; |
241699cd | 880 | } |
b9dc6f65 AV |
881 | i->count -= size; |
882 | /* ... and discard everything past that point */ | |
883 | pipe_truncate(i); | |
241699cd AV |
884 | } |
885 | ||
54c8195b PB |
886 | static void iov_iter_bvec_advance(struct iov_iter *i, size_t size) |
887 | { | |
18fa9af7 | 888 | const struct bio_vec *bvec, *end; |
54c8195b | 889 | |
18fa9af7 AV |
890 | if (!i->count) |
891 | return; | |
892 | i->count -= size; | |
893 | ||
894 | size += i->iov_offset; | |
54c8195b | 895 | |
18fa9af7 AV |
896 | for (bvec = i->bvec, end = bvec + i->nr_segs; bvec < end; bvec++) { |
897 | if (likely(size < bvec->bv_len)) | |
898 | break; | |
899 | size -= bvec->bv_len; | |
900 | } | |
901 | i->iov_offset = size; | |
902 | i->nr_segs -= bvec - i->bvec; | |
903 | i->bvec = bvec; | |
54c8195b PB |
904 | } |
905 | ||
185ac4d4 AV |
906 | static void iov_iter_iovec_advance(struct iov_iter *i, size_t size) |
907 | { | |
908 | const struct iovec *iov, *end; | |
909 | ||
910 | if (!i->count) | |
911 | return; | |
912 | i->count -= size; | |
913 | ||
914 | size += i->iov_offset; // from beginning of current segment | |
915 | for (iov = i->iov, end = iov + i->nr_segs; iov < end; iov++) { | |
916 | if (likely(size < iov->iov_len)) | |
917 | break; | |
918 | size -= iov->iov_len; | |
919 | } | |
920 | i->iov_offset = size; | |
921 | i->nr_segs -= iov - i->iov; | |
922 | i->iov = iov; | |
923 | } | |
924 | ||
62a8067a AV |
925 | void iov_iter_advance(struct iov_iter *i, size_t size) |
926 | { | |
3b3fc051 AV |
927 | if (unlikely(i->count < size)) |
928 | size = i->count; | |
fcb14cb1 AV |
929 | if (likely(iter_is_ubuf(i)) || unlikely(iov_iter_is_xarray(i))) { |
930 | i->iov_offset += size; | |
931 | i->count -= size; | |
932 | } else if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) { | |
185ac4d4 AV |
933 | /* iovec and kvec have identical layouts */ |
934 | iov_iter_iovec_advance(i, size); | |
935 | } else if (iov_iter_is_bvec(i)) { | |
936 | iov_iter_bvec_advance(i, size); | |
937 | } else if (iov_iter_is_pipe(i)) { | |
241699cd | 938 | pipe_advance(i, size); |
185ac4d4 AV |
939 | } else if (iov_iter_is_discard(i)) { |
940 | i->count -= size; | |
54c8195b | 941 | } |
62a8067a AV |
942 | } |
943 | EXPORT_SYMBOL(iov_iter_advance); | |
944 | ||
27c0e374 AV |
945 | void iov_iter_revert(struct iov_iter *i, size_t unroll) |
946 | { | |
947 | if (!unroll) | |
948 | return; | |
5b47d59a AV |
949 | if (WARN_ON(unroll > MAX_RW_COUNT)) |
950 | return; | |
27c0e374 | 951 | i->count += unroll; |
00e23707 | 952 | if (unlikely(iov_iter_is_pipe(i))) { |
27c0e374 | 953 | struct pipe_inode_info *pipe = i->pipe; |
8cefc107 DH |
954 | unsigned int p_mask = pipe->ring_size - 1; |
955 | unsigned int i_head = i->head; | |
27c0e374 AV |
956 | size_t off = i->iov_offset; |
957 | while (1) { | |
8cefc107 DH |
958 | struct pipe_buffer *b = &pipe->bufs[i_head & p_mask]; |
959 | size_t n = off - b->offset; | |
27c0e374 | 960 | if (unroll < n) { |
4fa55cef | 961 | off -= unroll; |
27c0e374 AV |
962 | break; |
963 | } | |
964 | unroll -= n; | |
8cefc107 | 965 | if (!unroll && i_head == i->start_head) { |
27c0e374 AV |
966 | off = 0; |
967 | break; | |
968 | } | |
8cefc107 DH |
969 | i_head--; |
970 | b = &pipe->bufs[i_head & p_mask]; | |
971 | off = b->offset + b->len; | |
27c0e374 AV |
972 | } |
973 | i->iov_offset = off; | |
8cefc107 | 974 | i->head = i_head; |
27c0e374 AV |
975 | pipe_truncate(i); |
976 | return; | |
977 | } | |
9ea9ce04 DH |
978 | if (unlikely(iov_iter_is_discard(i))) |
979 | return; | |
27c0e374 AV |
980 | if (unroll <= i->iov_offset) { |
981 | i->iov_offset -= unroll; | |
982 | return; | |
983 | } | |
984 | unroll -= i->iov_offset; | |
fcb14cb1 | 985 | if (iov_iter_is_xarray(i) || iter_is_ubuf(i)) { |
7ff50620 DH |
986 | BUG(); /* We should never go beyond the start of the specified |
987 | * range since we might then be straying into pages that | |
988 | * aren't pinned. | |
989 | */ | |
990 | } else if (iov_iter_is_bvec(i)) { | |
27c0e374 AV |
991 | const struct bio_vec *bvec = i->bvec; |
992 | while (1) { | |
993 | size_t n = (--bvec)->bv_len; | |
994 | i->nr_segs++; | |
995 | if (unroll <= n) { | |
996 | i->bvec = bvec; | |
997 | i->iov_offset = n - unroll; | |
998 | return; | |
999 | } | |
1000 | unroll -= n; | |
1001 | } | |
1002 | } else { /* same logics for iovec and kvec */ | |
1003 | const struct iovec *iov = i->iov; | |
1004 | while (1) { | |
1005 | size_t n = (--iov)->iov_len; | |
1006 | i->nr_segs++; | |
1007 | if (unroll <= n) { | |
1008 | i->iov = iov; | |
1009 | i->iov_offset = n - unroll; | |
1010 | return; | |
1011 | } | |
1012 | unroll -= n; | |
1013 | } | |
1014 | } | |
1015 | } | |
1016 | EXPORT_SYMBOL(iov_iter_revert); | |
1017 | ||
62a8067a AV |
1018 | /* |
1019 | * Return the count of just the current iov_iter segment. | |
1020 | */ | |
1021 | size_t iov_iter_single_seg_count(const struct iov_iter *i) | |
1022 | { | |
28f38db7 AV |
1023 | if (i->nr_segs > 1) { |
1024 | if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) | |
1025 | return min(i->count, i->iov->iov_len - i->iov_offset); | |
1026 | if (iov_iter_is_bvec(i)) | |
1027 | return min(i->count, i->bvec->bv_len - i->iov_offset); | |
1028 | } | |
1029 | return i->count; | |
62a8067a AV |
1030 | } |
1031 | EXPORT_SYMBOL(iov_iter_single_seg_count); | |
1032 | ||
aa563d7b | 1033 | void iov_iter_kvec(struct iov_iter *i, unsigned int direction, |
05afcb77 | 1034 | const struct kvec *kvec, unsigned long nr_segs, |
abb78f87 AV |
1035 | size_t count) |
1036 | { | |
aa563d7b | 1037 | WARN_ON(direction & ~(READ | WRITE)); |
8cd54c1c AV |
1038 | *i = (struct iov_iter){ |
1039 | .iter_type = ITER_KVEC, | |
1040 | .data_source = direction, | |
1041 | .kvec = kvec, | |
1042 | .nr_segs = nr_segs, | |
1043 | .iov_offset = 0, | |
1044 | .count = count | |
1045 | }; | |
abb78f87 AV |
1046 | } |
1047 | EXPORT_SYMBOL(iov_iter_kvec); | |
1048 | ||
aa563d7b | 1049 | void iov_iter_bvec(struct iov_iter *i, unsigned int direction, |
05afcb77 AV |
1050 | const struct bio_vec *bvec, unsigned long nr_segs, |
1051 | size_t count) | |
1052 | { | |
aa563d7b | 1053 | WARN_ON(direction & ~(READ | WRITE)); |
8cd54c1c AV |
1054 | *i = (struct iov_iter){ |
1055 | .iter_type = ITER_BVEC, | |
1056 | .data_source = direction, | |
1057 | .bvec = bvec, | |
1058 | .nr_segs = nr_segs, | |
1059 | .iov_offset = 0, | |
1060 | .count = count | |
1061 | }; | |
05afcb77 AV |
1062 | } |
1063 | EXPORT_SYMBOL(iov_iter_bvec); | |
1064 | ||
aa563d7b | 1065 | void iov_iter_pipe(struct iov_iter *i, unsigned int direction, |
241699cd AV |
1066 | struct pipe_inode_info *pipe, |
1067 | size_t count) | |
1068 | { | |
aa563d7b | 1069 | BUG_ON(direction != READ); |
8cefc107 | 1070 | WARN_ON(pipe_full(pipe->head, pipe->tail, pipe->ring_size)); |
8cd54c1c AV |
1071 | *i = (struct iov_iter){ |
1072 | .iter_type = ITER_PIPE, | |
1073 | .data_source = false, | |
1074 | .pipe = pipe, | |
1075 | .head = pipe->head, | |
1076 | .start_head = pipe->head, | |
1077 | .iov_offset = 0, | |
1078 | .count = count | |
1079 | }; | |
241699cd AV |
1080 | } |
1081 | EXPORT_SYMBOL(iov_iter_pipe); | |
1082 | ||
7ff50620 DH |
1083 | /** |
1084 | * iov_iter_xarray - Initialise an I/O iterator to use the pages in an xarray | |
1085 | * @i: The iterator to initialise. | |
1086 | * @direction: The direction of the transfer. | |
1087 | * @xarray: The xarray to access. | |
1088 | * @start: The start file position. | |
1089 | * @count: The size of the I/O buffer in bytes. | |
1090 | * | |
1091 | * Set up an I/O iterator to either draw data out of the pages attached to an | |
1092 | * inode or to inject data into those pages. The pages *must* be prevented | |
1093 | * from evaporation, either by taking a ref on them or locking them by the | |
1094 | * caller. | |
1095 | */ | |
1096 | void iov_iter_xarray(struct iov_iter *i, unsigned int direction, | |
1097 | struct xarray *xarray, loff_t start, size_t count) | |
1098 | { | |
1099 | BUG_ON(direction & ~1); | |
8cd54c1c AV |
1100 | *i = (struct iov_iter) { |
1101 | .iter_type = ITER_XARRAY, | |
1102 | .data_source = direction, | |
1103 | .xarray = xarray, | |
1104 | .xarray_start = start, | |
1105 | .count = count, | |
1106 | .iov_offset = 0 | |
1107 | }; | |
7ff50620 DH |
1108 | } |
1109 | EXPORT_SYMBOL(iov_iter_xarray); | |
1110 | ||
9ea9ce04 DH |
1111 | /** |
1112 | * iov_iter_discard - Initialise an I/O iterator that discards data | |
1113 | * @i: The iterator to initialise. | |
1114 | * @direction: The direction of the transfer. | |
1115 | * @count: The size of the I/O buffer in bytes. | |
1116 | * | |
1117 | * Set up an I/O iterator that just discards everything that's written to it. | |
1118 | * It's only available as a READ iterator. | |
1119 | */ | |
1120 | void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count) | |
1121 | { | |
1122 | BUG_ON(direction != READ); | |
8cd54c1c AV |
1123 | *i = (struct iov_iter){ |
1124 | .iter_type = ITER_DISCARD, | |
1125 | .data_source = false, | |
1126 | .count = count, | |
1127 | .iov_offset = 0 | |
1128 | }; | |
9ea9ce04 DH |
1129 | } |
1130 | EXPORT_SYMBOL(iov_iter_discard); | |
1131 | ||
cfa320f7 KB |
1132 | static bool iov_iter_aligned_iovec(const struct iov_iter *i, unsigned addr_mask, |
1133 | unsigned len_mask) | |
1134 | { | |
1135 | size_t size = i->count; | |
1136 | size_t skip = i->iov_offset; | |
1137 | unsigned k; | |
1138 | ||
1139 | for (k = 0; k < i->nr_segs; k++, skip = 0) { | |
1140 | size_t len = i->iov[k].iov_len - skip; | |
1141 | ||
1142 | if (len > size) | |
1143 | len = size; | |
1144 | if (len & len_mask) | |
1145 | return false; | |
1146 | if ((unsigned long)(i->iov[k].iov_base + skip) & addr_mask) | |
1147 | return false; | |
1148 | ||
1149 | size -= len; | |
1150 | if (!size) | |
1151 | break; | |
1152 | } | |
1153 | return true; | |
1154 | } | |
1155 | ||
1156 | static bool iov_iter_aligned_bvec(const struct iov_iter *i, unsigned addr_mask, | |
1157 | unsigned len_mask) | |
1158 | { | |
1159 | size_t size = i->count; | |
1160 | unsigned skip = i->iov_offset; | |
1161 | unsigned k; | |
1162 | ||
1163 | for (k = 0; k < i->nr_segs; k++, skip = 0) { | |
1164 | size_t len = i->bvec[k].bv_len - skip; | |
1165 | ||
1166 | if (len > size) | |
1167 | len = size; | |
1168 | if (len & len_mask) | |
1169 | return false; | |
1170 | if ((unsigned long)(i->bvec[k].bv_offset + skip) & addr_mask) | |
1171 | return false; | |
1172 | ||
1173 | size -= len; | |
1174 | if (!size) | |
1175 | break; | |
1176 | } | |
1177 | return true; | |
1178 | } | |
1179 | ||
1180 | /** | |
1181 | * iov_iter_is_aligned() - Check if the addresses and lengths of each segments | |
1182 | * are aligned to the parameters. | |
1183 | * | |
1184 | * @i: &struct iov_iter to restore | |
1185 | * @addr_mask: bit mask to check against the iov element's addresses | |
1186 | * @len_mask: bit mask to check against the iov element's lengths | |
1187 | * | |
1188 | * Return: false if any addresses or lengths intersect with the provided masks | |
1189 | */ | |
1190 | bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask, | |
1191 | unsigned len_mask) | |
1192 | { | |
fcb14cb1 AV |
1193 | if (likely(iter_is_ubuf(i))) { |
1194 | if (i->count & len_mask) | |
1195 | return false; | |
1196 | if ((unsigned long)(i->ubuf + i->iov_offset) & addr_mask) | |
1197 | return false; | |
1198 | return true; | |
1199 | } | |
1200 | ||
cfa320f7 KB |
1201 | if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) |
1202 | return iov_iter_aligned_iovec(i, addr_mask, len_mask); | |
1203 | ||
1204 | if (iov_iter_is_bvec(i)) | |
1205 | return iov_iter_aligned_bvec(i, addr_mask, len_mask); | |
1206 | ||
1207 | if (iov_iter_is_pipe(i)) { | |
1208 | unsigned int p_mask = i->pipe->ring_size - 1; | |
1209 | size_t size = i->count; | |
1210 | ||
1211 | if (size & len_mask) | |
1212 | return false; | |
1213 | if (size && allocated(&i->pipe->bufs[i->head & p_mask])) { | |
1214 | if (i->iov_offset & addr_mask) | |
1215 | return false; | |
1216 | } | |
1217 | ||
1218 | return true; | |
1219 | } | |
1220 | ||
1221 | if (iov_iter_is_xarray(i)) { | |
1222 | if (i->count & len_mask) | |
1223 | return false; | |
1224 | if ((i->xarray_start + i->iov_offset) & addr_mask) | |
1225 | return false; | |
1226 | } | |
1227 | ||
1228 | return true; | |
1229 | } | |
1230 | EXPORT_SYMBOL_GPL(iov_iter_is_aligned); | |
1231 | ||
9221d2e3 | 1232 | static unsigned long iov_iter_alignment_iovec(const struct iov_iter *i) |
62a8067a | 1233 | { |
04a31165 AV |
1234 | unsigned long res = 0; |
1235 | size_t size = i->count; | |
9221d2e3 AV |
1236 | size_t skip = i->iov_offset; |
1237 | unsigned k; | |
1238 | ||
1239 | for (k = 0; k < i->nr_segs; k++, skip = 0) { | |
1240 | size_t len = i->iov[k].iov_len - skip; | |
1241 | if (len) { | |
1242 | res |= (unsigned long)i->iov[k].iov_base + skip; | |
1243 | if (len > size) | |
1244 | len = size; | |
1245 | res |= len; | |
1246 | size -= len; | |
1247 | if (!size) | |
1248 | break; | |
1249 | } | |
1250 | } | |
1251 | return res; | |
1252 | } | |
04a31165 | 1253 | |
9221d2e3 AV |
1254 | static unsigned long iov_iter_alignment_bvec(const struct iov_iter *i) |
1255 | { | |
1256 | unsigned res = 0; | |
1257 | size_t size = i->count; | |
1258 | unsigned skip = i->iov_offset; | |
1259 | unsigned k; | |
1260 | ||
1261 | for (k = 0; k < i->nr_segs; k++, skip = 0) { | |
1262 | size_t len = i->bvec[k].bv_len - skip; | |
1263 | res |= (unsigned long)i->bvec[k].bv_offset + skip; | |
1264 | if (len > size) | |
1265 | len = size; | |
1266 | res |= len; | |
1267 | size -= len; | |
1268 | if (!size) | |
1269 | break; | |
1270 | } | |
1271 | return res; | |
1272 | } | |
1273 | ||
1274 | unsigned long iov_iter_alignment(const struct iov_iter *i) | |
1275 | { | |
fcb14cb1 AV |
1276 | if (likely(iter_is_ubuf(i))) { |
1277 | size_t size = i->count; | |
1278 | if (size) | |
1279 | return ((unsigned long)i->ubuf + i->iov_offset) | size; | |
1280 | return 0; | |
1281 | } | |
1282 | ||
9221d2e3 AV |
1283 | /* iovec and kvec have identical layouts */ |
1284 | if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) | |
1285 | return iov_iter_alignment_iovec(i); | |
1286 | ||
1287 | if (iov_iter_is_bvec(i)) | |
1288 | return iov_iter_alignment_bvec(i); | |
1289 | ||
1290 | if (iov_iter_is_pipe(i)) { | |
9221d2e3 | 1291 | size_t size = i->count; |
e0ff126e | 1292 | |
2dcedb2a | 1293 | if (size && i->iov_offset && allocated(pipe_buf(i->pipe, i->head))) |
241699cd AV |
1294 | return size | i->iov_offset; |
1295 | return size; | |
1296 | } | |
9221d2e3 AV |
1297 | |
1298 | if (iov_iter_is_xarray(i)) | |
3d14ec1f | 1299 | return (i->xarray_start + i->iov_offset) | i->count; |
9221d2e3 AV |
1300 | |
1301 | return 0; | |
62a8067a AV |
1302 | } |
1303 | EXPORT_SYMBOL(iov_iter_alignment); | |
1304 | ||
357f435d AV |
1305 | unsigned long iov_iter_gap_alignment(const struct iov_iter *i) |
1306 | { | |
33844e66 | 1307 | unsigned long res = 0; |
610c7a71 | 1308 | unsigned long v = 0; |
357f435d | 1309 | size_t size = i->count; |
610c7a71 | 1310 | unsigned k; |
357f435d | 1311 | |
fcb14cb1 AV |
1312 | if (iter_is_ubuf(i)) |
1313 | return 0; | |
1314 | ||
610c7a71 | 1315 | if (WARN_ON(!iter_is_iovec(i))) |
241699cd | 1316 | return ~0U; |
241699cd | 1317 | |
610c7a71 AV |
1318 | for (k = 0; k < i->nr_segs; k++) { |
1319 | if (i->iov[k].iov_len) { | |
1320 | unsigned long base = (unsigned long)i->iov[k].iov_base; | |
1321 | if (v) // if not the first one | |
1322 | res |= base | v; // this start | previous end | |
1323 | v = base + i->iov[k].iov_len; | |
1324 | if (size <= i->iov[k].iov_len) | |
1325 | break; | |
1326 | size -= i->iov[k].iov_len; | |
1327 | } | |
1328 | } | |
33844e66 | 1329 | return res; |
357f435d AV |
1330 | } |
1331 | EXPORT_SYMBOL(iov_iter_gap_alignment); | |
1332 | ||
e76b6312 | 1333 | static inline ssize_t __pipe_get_pages(struct iov_iter *i, |
241699cd AV |
1334 | size_t maxsize, |
1335 | struct page **pages, | |
8cefc107 | 1336 | int iter_head, |
241699cd AV |
1337 | size_t *start) |
1338 | { | |
1339 | struct pipe_inode_info *pipe = i->pipe; | |
8cefc107 DH |
1340 | unsigned int p_mask = pipe->ring_size - 1; |
1341 | ssize_t n = push_pipe(i, maxsize, &iter_head, start); | |
241699cd AV |
1342 | if (!n) |
1343 | return -EFAULT; | |
1344 | ||
1345 | maxsize = n; | |
1346 | n += *start; | |
1689c73a | 1347 | while (n > 0) { |
8cefc107 DH |
1348 | get_page(*pages++ = pipe->bufs[iter_head & p_mask].page); |
1349 | iter_head++; | |
241699cd AV |
1350 | n -= PAGE_SIZE; |
1351 | } | |
1352 | ||
1353 | return maxsize; | |
1354 | } | |
1355 | ||
1356 | static ssize_t pipe_get_pages(struct iov_iter *i, | |
1357 | struct page **pages, size_t maxsize, unsigned maxpages, | |
1358 | size_t *start) | |
1359 | { | |
8cefc107 | 1360 | unsigned int iter_head, npages; |
241699cd | 1361 | size_t capacity; |
241699cd AV |
1362 | |
1363 | if (!sanity(i)) | |
1364 | return -EFAULT; | |
1365 | ||
8cefc107 DH |
1366 | data_start(i, &iter_head, start); |
1367 | /* Amount of free space: some of this one + all after this one */ | |
1368 | npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe); | |
1369 | capacity = min(npages, maxpages) * PAGE_SIZE - *start; | |
241699cd | 1370 | |
8cefc107 | 1371 | return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, start); |
241699cd AV |
1372 | } |
1373 | ||
7ff50620 DH |
1374 | static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa, |
1375 | pgoff_t index, unsigned int nr_pages) | |
1376 | { | |
1377 | XA_STATE(xas, xa, index); | |
1378 | struct page *page; | |
1379 | unsigned int ret = 0; | |
1380 | ||
1381 | rcu_read_lock(); | |
1382 | for (page = xas_load(&xas); page; page = xas_next(&xas)) { | |
1383 | if (xas_retry(&xas, page)) | |
1384 | continue; | |
1385 | ||
1386 | /* Has the page moved or been split? */ | |
1387 | if (unlikely(page != xas_reload(&xas))) { | |
1388 | xas_reset(&xas); | |
1389 | continue; | |
1390 | } | |
1391 | ||
1392 | pages[ret] = find_subpage(page, xas.xa_index); | |
1393 | get_page(pages[ret]); | |
1394 | if (++ret == nr_pages) | |
1395 | break; | |
1396 | } | |
1397 | rcu_read_unlock(); | |
1398 | return ret; | |
1399 | } | |
1400 | ||
1401 | static ssize_t iter_xarray_get_pages(struct iov_iter *i, | |
1402 | struct page **pages, size_t maxsize, | |
1403 | unsigned maxpages, size_t *_start_offset) | |
1404 | { | |
1405 | unsigned nr, offset; | |
1406 | pgoff_t index, count; | |
6c776766 | 1407 | size_t size = maxsize; |
7ff50620 DH |
1408 | loff_t pos; |
1409 | ||
1410 | if (!size || !maxpages) | |
1411 | return 0; | |
1412 | ||
1413 | pos = i->xarray_start + i->iov_offset; | |
1414 | index = pos >> PAGE_SHIFT; | |
1415 | offset = pos & ~PAGE_MASK; | |
1416 | *_start_offset = offset; | |
1417 | ||
1418 | count = 1; | |
1419 | if (size > PAGE_SIZE - offset) { | |
1420 | size -= PAGE_SIZE - offset; | |
1421 | count += size >> PAGE_SHIFT; | |
1422 | size &= ~PAGE_MASK; | |
1423 | if (size) | |
1424 | count++; | |
1425 | } | |
1426 | ||
1427 | if (count > maxpages) | |
1428 | count = maxpages; | |
1429 | ||
1430 | nr = iter_xarray_populate_pages(pages, i->xarray, index, count); | |
1431 | if (nr == 0) | |
1432 | return 0; | |
1433 | ||
1c27f1fc | 1434 | return min_t(size_t, nr * PAGE_SIZE - offset, maxsize); |
7ff50620 DH |
1435 | } |
1436 | ||
fcb14cb1 | 1437 | /* must be done on non-empty ITER_UBUF or ITER_IOVEC one */ |
dd45ab9d | 1438 | static unsigned long first_iovec_segment(const struct iov_iter *i, size_t *size) |
3d671ca6 AV |
1439 | { |
1440 | size_t skip; | |
1441 | long k; | |
1442 | ||
fcb14cb1 AV |
1443 | if (iter_is_ubuf(i)) |
1444 | return (unsigned long)i->ubuf + i->iov_offset; | |
1445 | ||
3d671ca6 | 1446 | for (k = 0, skip = i->iov_offset; k < i->nr_segs; k++, skip = 0) { |
3d671ca6 AV |
1447 | size_t len = i->iov[k].iov_len - skip; |
1448 | ||
1449 | if (unlikely(!len)) | |
1450 | continue; | |
59dbd7d0 AV |
1451 | if (*size > len) |
1452 | *size = len; | |
dd45ab9d | 1453 | return (unsigned long)i->iov[k].iov_base + skip; |
3d671ca6 AV |
1454 | } |
1455 | BUG(); // if it had been empty, we wouldn't get called | |
1456 | } | |
1457 | ||
1458 | /* must be done on non-empty ITER_BVEC one */ | |
1459 | static struct page *first_bvec_segment(const struct iov_iter *i, | |
59dbd7d0 | 1460 | size_t *size, size_t *start) |
3d671ca6 AV |
1461 | { |
1462 | struct page *page; | |
1463 | size_t skip = i->iov_offset, len; | |
1464 | ||
1465 | len = i->bvec->bv_len - skip; | |
59dbd7d0 AV |
1466 | if (*size > len) |
1467 | *size = len; | |
3d671ca6 AV |
1468 | skip += i->bvec->bv_offset; |
1469 | page = i->bvec->bv_page + skip / PAGE_SIZE; | |
dda8e5d1 | 1470 | *start = skip % PAGE_SIZE; |
3d671ca6 AV |
1471 | return page; |
1472 | } | |
1473 | ||
62a8067a | 1474 | ssize_t iov_iter_get_pages(struct iov_iter *i, |
2c80929c | 1475 | struct page **pages, size_t maxsize, unsigned maxpages, |
62a8067a AV |
1476 | size_t *start) |
1477 | { | |
3d671ca6 AV |
1478 | int n, res; |
1479 | ||
e5393fae AV |
1480 | if (maxsize > i->count) |
1481 | maxsize = i->count; | |
3d671ca6 AV |
1482 | if (!maxsize) |
1483 | return 0; | |
7392ed17 AV |
1484 | if (maxsize > MAX_RW_COUNT) |
1485 | maxsize = MAX_RW_COUNT; | |
e5393fae | 1486 | |
fcb14cb1 | 1487 | if (likely(user_backed_iter(i))) { |
3337ab08 | 1488 | unsigned int gup_flags = 0; |
3d671ca6 | 1489 | unsigned long addr; |
e5393fae | 1490 | |
3337ab08 AG |
1491 | if (iov_iter_rw(i) != WRITE) |
1492 | gup_flags |= FOLL_WRITE; | |
1493 | if (i->nofault) | |
1494 | gup_flags |= FOLL_NOFAULT; | |
1495 | ||
dd45ab9d AV |
1496 | addr = first_iovec_segment(i, &maxsize); |
1497 | *start = addr % PAGE_SIZE; | |
1498 | addr &= PAGE_MASK; | |
59dbd7d0 | 1499 | n = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE); |
dda8e5d1 AV |
1500 | if (n > maxpages) |
1501 | n = maxpages; | |
3337ab08 | 1502 | res = get_user_pages_fast(addr, n, gup_flags, pages); |
814a6674 | 1503 | if (unlikely(res <= 0)) |
e5393fae | 1504 | return res; |
59dbd7d0 | 1505 | return min_t(size_t, maxsize, res * PAGE_SIZE - *start); |
3d671ca6 AV |
1506 | } |
1507 | if (iov_iter_is_bvec(i)) { | |
1508 | struct page *page; | |
1509 | ||
59dbd7d0 AV |
1510 | page = first_bvec_segment(i, &maxsize, start); |
1511 | n = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE); | |
dda8e5d1 AV |
1512 | if (n > maxpages) |
1513 | n = maxpages; | |
1514 | for (int k = 0; k < n; k++) | |
3d671ca6 | 1515 | get_page(*pages++ = page++); |
59dbd7d0 | 1516 | return min_t(size_t, maxsize, n * PAGE_SIZE - *start); |
3d671ca6 AV |
1517 | } |
1518 | if (iov_iter_is_pipe(i)) | |
1519 | return pipe_get_pages(i, pages, maxsize, maxpages, start); | |
1520 | if (iov_iter_is_xarray(i)) | |
1521 | return iter_xarray_get_pages(i, pages, maxsize, maxpages, start); | |
1522 | return -EFAULT; | |
62a8067a AV |
1523 | } |
1524 | EXPORT_SYMBOL(iov_iter_get_pages); | |
1525 | ||
1b17f1f2 AV |
1526 | static struct page **get_pages_array(size_t n) |
1527 | { | |
752ade68 | 1528 | return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL); |
1b17f1f2 AV |
1529 | } |
1530 | ||
241699cd AV |
1531 | static ssize_t pipe_get_pages_alloc(struct iov_iter *i, |
1532 | struct page ***pages, size_t maxsize, | |
1533 | size_t *start) | |
1534 | { | |
1535 | struct page **p; | |
8cefc107 | 1536 | unsigned int iter_head, npages; |
d7760d63 | 1537 | ssize_t n; |
241699cd AV |
1538 | |
1539 | if (!sanity(i)) | |
1540 | return -EFAULT; | |
1541 | ||
8cefc107 DH |
1542 | data_start(i, &iter_head, start); |
1543 | /* Amount of free space: some of this one + all after this one */ | |
1544 | npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe); | |
241699cd AV |
1545 | n = npages * PAGE_SIZE - *start; |
1546 | if (maxsize > n) | |
1547 | maxsize = n; | |
1548 | else | |
1549 | npages = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE); | |
1550 | p = get_pages_array(npages); | |
1551 | if (!p) | |
1552 | return -ENOMEM; | |
8cefc107 | 1553 | n = __pipe_get_pages(i, maxsize, p, iter_head, start); |
241699cd AV |
1554 | if (n > 0) |
1555 | *pages = p; | |
1556 | else | |
1557 | kvfree(p); | |
1558 | return n; | |
1559 | } | |
1560 | ||
7ff50620 DH |
1561 | static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i, |
1562 | struct page ***pages, size_t maxsize, | |
1563 | size_t *_start_offset) | |
1564 | { | |
1565 | struct page **p; | |
1566 | unsigned nr, offset; | |
1567 | pgoff_t index, count; | |
6c776766 | 1568 | size_t size = maxsize; |
7ff50620 DH |
1569 | loff_t pos; |
1570 | ||
1571 | if (!size) | |
1572 | return 0; | |
1573 | ||
1574 | pos = i->xarray_start + i->iov_offset; | |
1575 | index = pos >> PAGE_SHIFT; | |
1576 | offset = pos & ~PAGE_MASK; | |
1577 | *_start_offset = offset; | |
1578 | ||
1579 | count = 1; | |
1580 | if (size > PAGE_SIZE - offset) { | |
1581 | size -= PAGE_SIZE - offset; | |
1582 | count += size >> PAGE_SHIFT; | |
1583 | size &= ~PAGE_MASK; | |
1584 | if (size) | |
1585 | count++; | |
1586 | } | |
1587 | ||
1588 | p = get_pages_array(count); | |
1589 | if (!p) | |
1590 | return -ENOMEM; | |
1591 | *pages = p; | |
1592 | ||
1593 | nr = iter_xarray_populate_pages(p, i->xarray, index, count); | |
1594 | if (nr == 0) | |
1595 | return 0; | |
1596 | ||
1c27f1fc | 1597 | return min_t(size_t, nr * PAGE_SIZE - offset, maxsize); |
7ff50620 DH |
1598 | } |
1599 | ||
62a8067a AV |
1600 | ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, |
1601 | struct page ***pages, size_t maxsize, | |
1602 | size_t *start) | |
1603 | { | |
1b17f1f2 | 1604 | struct page **p; |
3d671ca6 | 1605 | int n, res; |
1b17f1f2 AV |
1606 | |
1607 | if (maxsize > i->count) | |
1608 | maxsize = i->count; | |
3d671ca6 AV |
1609 | if (!maxsize) |
1610 | return 0; | |
7392ed17 AV |
1611 | if (maxsize > MAX_RW_COUNT) |
1612 | maxsize = MAX_RW_COUNT; | |
1b17f1f2 | 1613 | |
fcb14cb1 | 1614 | if (likely(user_backed_iter(i))) { |
3337ab08 | 1615 | unsigned int gup_flags = 0; |
3d671ca6 | 1616 | unsigned long addr; |
1b17f1f2 | 1617 | |
3337ab08 AG |
1618 | if (iov_iter_rw(i) != WRITE) |
1619 | gup_flags |= FOLL_WRITE; | |
1620 | if (i->nofault) | |
1621 | gup_flags |= FOLL_NOFAULT; | |
1622 | ||
dd45ab9d AV |
1623 | addr = first_iovec_segment(i, &maxsize); |
1624 | *start = addr % PAGE_SIZE; | |
1625 | addr &= PAGE_MASK; | |
59dbd7d0 | 1626 | n = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE); |
1b17f1f2 AV |
1627 | p = get_pages_array(n); |
1628 | if (!p) | |
1629 | return -ENOMEM; | |
3337ab08 | 1630 | res = get_user_pages_fast(addr, n, gup_flags, p); |
814a6674 | 1631 | if (unlikely(res <= 0)) { |
1b17f1f2 | 1632 | kvfree(p); |
814a6674 | 1633 | *pages = NULL; |
1b17f1f2 AV |
1634 | return res; |
1635 | } | |
1636 | *pages = p; | |
59dbd7d0 | 1637 | return min_t(size_t, maxsize, res * PAGE_SIZE - *start); |
3d671ca6 AV |
1638 | } |
1639 | if (iov_iter_is_bvec(i)) { | |
1640 | struct page *page; | |
1641 | ||
59dbd7d0 AV |
1642 | page = first_bvec_segment(i, &maxsize, start); |
1643 | n = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE); | |
3d671ca6 | 1644 | *pages = p = get_pages_array(n); |
1b17f1f2 AV |
1645 | if (!p) |
1646 | return -ENOMEM; | |
dda8e5d1 | 1647 | for (int k = 0; k < n; k++) |
3d671ca6 | 1648 | get_page(*p++ = page++); |
59dbd7d0 | 1649 | return min_t(size_t, maxsize, n * PAGE_SIZE - *start); |
3d671ca6 AV |
1650 | } |
1651 | if (iov_iter_is_pipe(i)) | |
1652 | return pipe_get_pages_alloc(i, pages, maxsize, start); | |
1653 | if (iov_iter_is_xarray(i)) | |
1654 | return iter_xarray_get_pages_alloc(i, pages, maxsize, start); | |
1655 | return -EFAULT; | |
62a8067a AV |
1656 | } |
1657 | EXPORT_SYMBOL(iov_iter_get_pages_alloc); | |
1658 | ||
a604ec7e AV |
1659 | size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, |
1660 | struct iov_iter *i) | |
1661 | { | |
a604ec7e | 1662 | __wsum sum, next; |
a604ec7e | 1663 | sum = *csum; |
9ea9ce04 | 1664 | if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { |
241699cd AV |
1665 | WARN_ON(1); |
1666 | return 0; | |
1667 | } | |
7baa5099 AV |
1668 | iterate_and_advance(i, bytes, base, len, off, ({ |
1669 | next = csum_and_copy_from_user(base, addr + off, len); | |
2495bdcc | 1670 | sum = csum_block_add(sum, next, off); |
7baa5099 | 1671 | next ? 0 : len; |
a604ec7e | 1672 | }), ({ |
7baa5099 | 1673 | sum = csum_and_memcpy(addr + off, base, len, sum, off); |
a604ec7e AV |
1674 | }) |
1675 | ) | |
1676 | *csum = sum; | |
1677 | return bytes; | |
1678 | } | |
1679 | EXPORT_SYMBOL(csum_and_copy_from_iter); | |
1680 | ||
52cbd23a | 1681 | size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate, |
a604ec7e AV |
1682 | struct iov_iter *i) |
1683 | { | |
52cbd23a | 1684 | struct csum_state *csstate = _csstate; |
a604ec7e | 1685 | __wsum sum, next; |
78e1f386 | 1686 | |
78e1f386 | 1687 | if (unlikely(iov_iter_is_discard(i))) { |
241699cd AV |
1688 | WARN_ON(1); /* for now */ |
1689 | return 0; | |
1690 | } | |
6852df12 AV |
1691 | |
1692 | sum = csum_shift(csstate->csum, csstate->off); | |
1693 | if (unlikely(iov_iter_is_pipe(i))) | |
1694 | bytes = csum_and_copy_to_pipe_iter(addr, bytes, i, &sum); | |
1695 | else iterate_and_advance(i, bytes, base, len, off, ({ | |
7baa5099 | 1696 | next = csum_and_copy_to_user(addr + off, base, len); |
2495bdcc | 1697 | sum = csum_block_add(sum, next, off); |
7baa5099 | 1698 | next ? 0 : len; |
a604ec7e | 1699 | }), ({ |
7baa5099 | 1700 | sum = csum_and_memcpy(base, addr + off, len, sum, off); |
a604ec7e AV |
1701 | }) |
1702 | ) | |
594e450b AV |
1703 | csstate->csum = csum_shift(sum, csstate->off); |
1704 | csstate->off += bytes; | |
a604ec7e AV |
1705 | return bytes; |
1706 | } | |
1707 | EXPORT_SYMBOL(csum_and_copy_to_iter); | |
1708 | ||
d05f4435 SG |
1709 | size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp, |
1710 | struct iov_iter *i) | |
1711 | { | |
7999096f | 1712 | #ifdef CONFIG_CRYPTO_HASH |
d05f4435 SG |
1713 | struct ahash_request *hash = hashp; |
1714 | struct scatterlist sg; | |
1715 | size_t copied; | |
1716 | ||
1717 | copied = copy_to_iter(addr, bytes, i); | |
1718 | sg_init_one(&sg, addr, copied); | |
1719 | ahash_request_set_crypt(hash, &sg, NULL, copied); | |
1720 | crypto_ahash_update(hash); | |
1721 | return copied; | |
27fad74a Y |
1722 | #else |
1723 | return 0; | |
1724 | #endif | |
d05f4435 SG |
1725 | } |
1726 | EXPORT_SYMBOL(hash_and_copy_to_iter); | |
1727 | ||
66531c65 | 1728 | static int iov_npages(const struct iov_iter *i, int maxpages) |
62a8067a | 1729 | { |
66531c65 AV |
1730 | size_t skip = i->iov_offset, size = i->count; |
1731 | const struct iovec *p; | |
e0f2dc40 AV |
1732 | int npages = 0; |
1733 | ||
66531c65 AV |
1734 | for (p = i->iov; size; skip = 0, p++) { |
1735 | unsigned offs = offset_in_page(p->iov_base + skip); | |
1736 | size_t len = min(p->iov_len - skip, size); | |
e0f2dc40 | 1737 | |
66531c65 AV |
1738 | if (len) { |
1739 | size -= len; | |
1740 | npages += DIV_ROUND_UP(offs + len, PAGE_SIZE); | |
1741 | if (unlikely(npages > maxpages)) | |
1742 | return maxpages; | |
1743 | } | |
1744 | } | |
1745 | return npages; | |
1746 | } | |
1747 | ||
1748 | static int bvec_npages(const struct iov_iter *i, int maxpages) | |
1749 | { | |
1750 | size_t skip = i->iov_offset, size = i->count; | |
1751 | const struct bio_vec *p; | |
1752 | int npages = 0; | |
1753 | ||
1754 | for (p = i->bvec; size; skip = 0, p++) { | |
1755 | unsigned offs = (p->bv_offset + skip) % PAGE_SIZE; | |
1756 | size_t len = min(p->bv_len - skip, size); | |
1757 | ||
1758 | size -= len; | |
1759 | npages += DIV_ROUND_UP(offs + len, PAGE_SIZE); | |
1760 | if (unlikely(npages > maxpages)) | |
1761 | return maxpages; | |
1762 | } | |
1763 | return npages; | |
1764 | } | |
1765 | ||
1766 | int iov_iter_npages(const struct iov_iter *i, int maxpages) | |
1767 | { | |
1768 | if (unlikely(!i->count)) | |
1769 | return 0; | |
fcb14cb1 AV |
1770 | if (likely(iter_is_ubuf(i))) { |
1771 | unsigned offs = offset_in_page(i->ubuf + i->iov_offset); | |
1772 | int npages = DIV_ROUND_UP(offs + i->count, PAGE_SIZE); | |
1773 | return min(npages, maxpages); | |
1774 | } | |
66531c65 AV |
1775 | /* iovec and kvec have identical layouts */ |
1776 | if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) | |
1777 | return iov_npages(i, maxpages); | |
1778 | if (iov_iter_is_bvec(i)) | |
1779 | return bvec_npages(i, maxpages); | |
1780 | if (iov_iter_is_pipe(i)) { | |
8cefc107 | 1781 | unsigned int iter_head; |
66531c65 | 1782 | int npages; |
241699cd | 1783 | size_t off; |
241699cd AV |
1784 | |
1785 | if (!sanity(i)) | |
1786 | return 0; | |
1787 | ||
8cefc107 | 1788 | data_start(i, &iter_head, &off); |
241699cd | 1789 | /* some of this one + all after this one */ |
66531c65 AV |
1790 | npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe); |
1791 | return min(npages, maxpages); | |
1792 | } | |
1793 | if (iov_iter_is_xarray(i)) { | |
e4f8df86 AV |
1794 | unsigned offset = (i->xarray_start + i->iov_offset) % PAGE_SIZE; |
1795 | int npages = DIV_ROUND_UP(offset + i->count, PAGE_SIZE); | |
66531c65 AV |
1796 | return min(npages, maxpages); |
1797 | } | |
1798 | return 0; | |
62a8067a | 1799 | } |
f67da30c | 1800 | EXPORT_SYMBOL(iov_iter_npages); |
4b8164b9 AV |
1801 | |
1802 | const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags) | |
1803 | { | |
1804 | *new = *old; | |
00e23707 | 1805 | if (unlikely(iov_iter_is_pipe(new))) { |
241699cd AV |
1806 | WARN_ON(1); |
1807 | return NULL; | |
1808 | } | |
00e23707 | 1809 | if (iov_iter_is_bvec(new)) |
4b8164b9 AV |
1810 | return new->bvec = kmemdup(new->bvec, |
1811 | new->nr_segs * sizeof(struct bio_vec), | |
1812 | flags); | |
fcb14cb1 | 1813 | else if (iov_iter_is_kvec(new) || iter_is_iovec(new)) |
4b8164b9 AV |
1814 | /* iovec and kvec have identical layout */ |
1815 | return new->iov = kmemdup(new->iov, | |
1816 | new->nr_segs * sizeof(struct iovec), | |
1817 | flags); | |
fcb14cb1 | 1818 | return NULL; |
4b8164b9 AV |
1819 | } |
1820 | EXPORT_SYMBOL(dup_iter); | |
bc917be8 | 1821 | |
bfdc5970 CH |
1822 | static int copy_compat_iovec_from_user(struct iovec *iov, |
1823 | const struct iovec __user *uvec, unsigned long nr_segs) | |
1824 | { | |
1825 | const struct compat_iovec __user *uiov = | |
1826 | (const struct compat_iovec __user *)uvec; | |
1827 | int ret = -EFAULT, i; | |
1828 | ||
a959a978 | 1829 | if (!user_access_begin(uiov, nr_segs * sizeof(*uiov))) |
bfdc5970 CH |
1830 | return -EFAULT; |
1831 | ||
1832 | for (i = 0; i < nr_segs; i++) { | |
1833 | compat_uptr_t buf; | |
1834 | compat_ssize_t len; | |
1835 | ||
1836 | unsafe_get_user(len, &uiov[i].iov_len, uaccess_end); | |
1837 | unsafe_get_user(buf, &uiov[i].iov_base, uaccess_end); | |
1838 | ||
1839 | /* check for compat_size_t not fitting in compat_ssize_t .. */ | |
1840 | if (len < 0) { | |
1841 | ret = -EINVAL; | |
1842 | goto uaccess_end; | |
1843 | } | |
1844 | iov[i].iov_base = compat_ptr(buf); | |
1845 | iov[i].iov_len = len; | |
1846 | } | |
1847 | ||
1848 | ret = 0; | |
1849 | uaccess_end: | |
1850 | user_access_end(); | |
1851 | return ret; | |
1852 | } | |
1853 | ||
1854 | static int copy_iovec_from_user(struct iovec *iov, | |
1855 | const struct iovec __user *uvec, unsigned long nr_segs) | |
fb041b59 DL |
1856 | { |
1857 | unsigned long seg; | |
fb041b59 | 1858 | |
bfdc5970 CH |
1859 | if (copy_from_user(iov, uvec, nr_segs * sizeof(*uvec))) |
1860 | return -EFAULT; | |
1861 | for (seg = 0; seg < nr_segs; seg++) { | |
1862 | if ((ssize_t)iov[seg].iov_len < 0) | |
1863 | return -EINVAL; | |
fb041b59 DL |
1864 | } |
1865 | ||
bfdc5970 CH |
1866 | return 0; |
1867 | } | |
1868 | ||
1869 | struct iovec *iovec_from_user(const struct iovec __user *uvec, | |
1870 | unsigned long nr_segs, unsigned long fast_segs, | |
1871 | struct iovec *fast_iov, bool compat) | |
1872 | { | |
1873 | struct iovec *iov = fast_iov; | |
1874 | int ret; | |
1875 | ||
fb041b59 | 1876 | /* |
bfdc5970 CH |
1877 | * SuS says "The readv() function *may* fail if the iovcnt argument was |
1878 | * less than or equal to 0, or greater than {IOV_MAX}. Linux has | |
1879 | * traditionally returned zero for zero segments, so... | |
fb041b59 | 1880 | */ |
bfdc5970 CH |
1881 | if (nr_segs == 0) |
1882 | return iov; | |
1883 | if (nr_segs > UIO_MAXIOV) | |
1884 | return ERR_PTR(-EINVAL); | |
fb041b59 DL |
1885 | if (nr_segs > fast_segs) { |
1886 | iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL); | |
bfdc5970 CH |
1887 | if (!iov) |
1888 | return ERR_PTR(-ENOMEM); | |
fb041b59 | 1889 | } |
bfdc5970 CH |
1890 | |
1891 | if (compat) | |
1892 | ret = copy_compat_iovec_from_user(iov, uvec, nr_segs); | |
1893 | else | |
1894 | ret = copy_iovec_from_user(iov, uvec, nr_segs); | |
1895 | if (ret) { | |
1896 | if (iov != fast_iov) | |
1897 | kfree(iov); | |
1898 | return ERR_PTR(ret); | |
1899 | } | |
1900 | ||
1901 | return iov; | |
1902 | } | |
1903 | ||
1904 | ssize_t __import_iovec(int type, const struct iovec __user *uvec, | |
1905 | unsigned nr_segs, unsigned fast_segs, struct iovec **iovp, | |
1906 | struct iov_iter *i, bool compat) | |
1907 | { | |
1908 | ssize_t total_len = 0; | |
1909 | unsigned long seg; | |
1910 | struct iovec *iov; | |
1911 | ||
1912 | iov = iovec_from_user(uvec, nr_segs, fast_segs, *iovp, compat); | |
1913 | if (IS_ERR(iov)) { | |
1914 | *iovp = NULL; | |
1915 | return PTR_ERR(iov); | |
fb041b59 DL |
1916 | } |
1917 | ||
1918 | /* | |
bfdc5970 CH |
1919 | * According to the Single Unix Specification we should return EINVAL if |
1920 | * an element length is < 0 when cast to ssize_t or if the total length | |
1921 | * would overflow the ssize_t return value of the system call. | |
fb041b59 DL |
1922 | * |
1923 | * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the | |
1924 | * overflow case. | |
1925 | */ | |
fb041b59 | 1926 | for (seg = 0; seg < nr_segs; seg++) { |
fb041b59 DL |
1927 | ssize_t len = (ssize_t)iov[seg].iov_len; |
1928 | ||
bfdc5970 CH |
1929 | if (!access_ok(iov[seg].iov_base, len)) { |
1930 | if (iov != *iovp) | |
1931 | kfree(iov); | |
1932 | *iovp = NULL; | |
1933 | return -EFAULT; | |
fb041b59 | 1934 | } |
bfdc5970 CH |
1935 | |
1936 | if (len > MAX_RW_COUNT - total_len) { | |
1937 | len = MAX_RW_COUNT - total_len; | |
fb041b59 DL |
1938 | iov[seg].iov_len = len; |
1939 | } | |
bfdc5970 | 1940 | total_len += len; |
fb041b59 | 1941 | } |
bfdc5970 CH |
1942 | |
1943 | iov_iter_init(i, type, iov, nr_segs, total_len); | |
1944 | if (iov == *iovp) | |
1945 | *iovp = NULL; | |
1946 | else | |
1947 | *iovp = iov; | |
1948 | return total_len; | |
fb041b59 DL |
1949 | } |
1950 | ||
ffecee4f VN |
1951 | /** |
1952 | * import_iovec() - Copy an array of &struct iovec from userspace | |
1953 | * into the kernel, check that it is valid, and initialize a new | |
1954 | * &struct iov_iter iterator to access it. | |
1955 | * | |
1956 | * @type: One of %READ or %WRITE. | |
bfdc5970 | 1957 | * @uvec: Pointer to the userspace array. |
ffecee4f VN |
1958 | * @nr_segs: Number of elements in userspace array. |
1959 | * @fast_segs: Number of elements in @iov. | |
bfdc5970 | 1960 | * @iovp: (input and output parameter) Pointer to pointer to (usually small |
ffecee4f VN |
1961 | * on-stack) kernel array. |
1962 | * @i: Pointer to iterator that will be initialized on success. | |
1963 | * | |
1964 | * If the array pointed to by *@iov is large enough to hold all @nr_segs, | |
1965 | * then this function places %NULL in *@iov on return. Otherwise, a new | |
1966 | * array will be allocated and the result placed in *@iov. This means that | |
1967 | * the caller may call kfree() on *@iov regardless of whether the small | |
1968 | * on-stack array was used or not (and regardless of whether this function | |
1969 | * returns an error or not). | |
1970 | * | |
87e5e6da | 1971 | * Return: Negative error code on error, bytes imported on success |
ffecee4f | 1972 | */ |
bfdc5970 | 1973 | ssize_t import_iovec(int type, const struct iovec __user *uvec, |
bc917be8 | 1974 | unsigned nr_segs, unsigned fast_segs, |
bfdc5970 | 1975 | struct iovec **iovp, struct iov_iter *i) |
bc917be8 | 1976 | { |
89cd35c5 CH |
1977 | return __import_iovec(type, uvec, nr_segs, fast_segs, iovp, i, |
1978 | in_compat_syscall()); | |
bc917be8 AV |
1979 | } |
1980 | EXPORT_SYMBOL(import_iovec); | |
1981 | ||
bc917be8 AV |
1982 | int import_single_range(int rw, void __user *buf, size_t len, |
1983 | struct iovec *iov, struct iov_iter *i) | |
1984 | { | |
1985 | if (len > MAX_RW_COUNT) | |
1986 | len = MAX_RW_COUNT; | |
96d4f267 | 1987 | if (unlikely(!access_ok(buf, len))) |
bc917be8 AV |
1988 | return -EFAULT; |
1989 | ||
1990 | iov->iov_base = buf; | |
1991 | iov->iov_len = len; | |
1992 | iov_iter_init(i, rw, iov, 1, len); | |
1993 | return 0; | |
1994 | } | |
e1267585 | 1995 | EXPORT_SYMBOL(import_single_range); |
8fb0f47a JA |
1996 | |
1997 | /** | |
1998 | * iov_iter_restore() - Restore a &struct iov_iter to the same state as when | |
1999 | * iov_iter_save_state() was called. | |
2000 | * | |
2001 | * @i: &struct iov_iter to restore | |
2002 | * @state: state to restore from | |
2003 | * | |
2004 | * Used after iov_iter_save_state() to bring restore @i, if operations may | |
2005 | * have advanced it. | |
2006 | * | |
2007 | * Note: only works on ITER_IOVEC, ITER_BVEC, and ITER_KVEC | |
2008 | */ | |
2009 | void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state) | |
2010 | { | |
2011 | if (WARN_ON_ONCE(!iov_iter_is_bvec(i) && !iter_is_iovec(i)) && | |
fcb14cb1 | 2012 | !iov_iter_is_kvec(i) && !iter_is_ubuf(i)) |
8fb0f47a JA |
2013 | return; |
2014 | i->iov_offset = state->iov_offset; | |
2015 | i->count = state->count; | |
fcb14cb1 AV |
2016 | if (iter_is_ubuf(i)) |
2017 | return; | |
8fb0f47a JA |
2018 | /* |
2019 | * For the *vec iters, nr_segs + iov is constant - if we increment | |
2020 | * the vec, then we also decrement the nr_segs count. Hence we don't | |
2021 | * need to track both of these, just one is enough and we can deduct | |
2022 | * the other from that. ITER_KVEC and ITER_IOVEC are the same struct | |
2023 | * size, so we can just increment the iov pointer as they are unionzed. | |
2024 | * ITER_BVEC _may_ be the same size on some archs, but on others it is | |
2025 | * not. Be safe and handle it separately. | |
2026 | */ | |
2027 | BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec)); | |
2028 | if (iov_iter_is_bvec(i)) | |
2029 | i->bvec -= state->nr_segs - i->nr_segs; | |
2030 | else | |
2031 | i->iov -= state->nr_segs - i->nr_segs; | |
2032 | i->nr_segs = state->nr_segs; | |
2033 | } |