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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
4f18cd31 | 2 | #include <linux/export.h> |
2f8b5444 | 3 | #include <linux/bvec.h> |
4d0e9df5 | 4 | #include <linux/fault-inject-usercopy.h> |
4f18cd31 AV |
5 | #include <linux/uio.h> |
6 | #include <linux/pagemap.h> | |
28961998 | 7 | #include <linux/highmem.h> |
91f79c43 AV |
8 | #include <linux/slab.h> |
9 | #include <linux/vmalloc.h> | |
241699cd | 10 | #include <linux/splice.h> |
bfdc5970 | 11 | #include <linux/compat.h> |
d05f4435 | 12 | #include <linux/scatterlist.h> |
d0ef4c36 | 13 | #include <linux/instrumented.h> |
f1982740 | 14 | #include <linux/iov_iter.h> |
4f18cd31 | 15 | |
f1982740 DH |
16 | static __always_inline |
17 | size_t copy_to_user_iter(void __user *iter_to, size_t progress, | |
18 | size_t len, void *from, void *priv2) | |
09fc68dc | 19 | { |
4d0e9df5 | 20 | if (should_fail_usercopy()) |
f1982740 DH |
21 | return len; |
22 | if (access_ok(iter_to, len)) { | |
23 | from += progress; | |
24 | instrument_copy_to_user(iter_to, from, len); | |
25 | len = raw_copy_to_user(iter_to, from, len); | |
09fc68dc | 26 | } |
f1982740 | 27 | return len; |
09fc68dc AV |
28 | } |
29 | ||
f1982740 DH |
30 | static __always_inline |
31 | size_t copy_to_user_iter_nofault(void __user *iter_to, size_t progress, | |
32 | size_t len, void *from, void *priv2) | |
4f80818b | 33 | { |
f1982740 | 34 | ssize_t res; |
4f80818b LS |
35 | |
36 | if (should_fail_usercopy()) | |
f1982740 | 37 | return len; |
4f80818b | 38 | |
f1982740 DH |
39 | from += progress; |
40 | res = copy_to_user_nofault(iter_to, from, len); | |
41 | return res < 0 ? len : res; | |
4f80818b LS |
42 | } |
43 | ||
f1982740 DH |
44 | static __always_inline |
45 | size_t copy_from_user_iter(void __user *iter_from, size_t progress, | |
46 | size_t len, void *to, void *priv2) | |
09fc68dc | 47 | { |
f1982740 | 48 | size_t res = len; |
33b75c1d | 49 | |
4d0e9df5 | 50 | if (should_fail_usercopy()) |
f1982740 DH |
51 | return len; |
52 | if (access_ok(iter_from, len)) { | |
53 | to += progress; | |
54 | instrument_copy_from_user_before(to, iter_from, len); | |
55 | res = raw_copy_from_user(to, iter_from, len); | |
56 | instrument_copy_from_user_after(to, iter_from, len, res); | |
09fc68dc | 57 | } |
33b75c1d | 58 | return res; |
09fc68dc AV |
59 | } |
60 | ||
f1982740 DH |
61 | static __always_inline |
62 | size_t memcpy_to_iter(void *iter_to, size_t progress, | |
63 | size_t len, void *from, void *priv2) | |
64 | { | |
65 | memcpy(iter_to, from + progress, len); | |
66 | return 0; | |
67 | } | |
68 | ||
69 | static __always_inline | |
70 | size_t memcpy_from_iter(void *iter_from, size_t progress, | |
71 | size_t len, void *to, void *priv2) | |
72 | { | |
73 | memcpy(to + progress, iter_from, len); | |
74 | return 0; | |
75 | } | |
76 | ||
171a0203 | 77 | /* |
a6294593 AG |
78 | * fault_in_iov_iter_readable - fault in iov iterator for reading |
79 | * @i: iterator | |
80 | * @size: maximum length | |
81 | * | |
171a0203 | 82 | * Fault in one or more iovecs of the given iov_iter, to a maximum length of |
a6294593 AG |
83 | * @size. For each iovec, fault in each page that constitutes the iovec. |
84 | * | |
85 | * Returns the number of bytes not faulted in (like copy_to_user() and | |
86 | * copy_from_user()). | |
171a0203 | 87 | * |
a6294593 | 88 | * Always returns 0 for non-userspace iterators. |
171a0203 | 89 | */ |
a6294593 | 90 | size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t size) |
171a0203 | 91 | { |
fcb14cb1 AV |
92 | if (iter_is_ubuf(i)) { |
93 | size_t n = min(size, iov_iter_count(i)); | |
94 | n -= fault_in_readable(i->ubuf + i->iov_offset, n); | |
95 | return size - n; | |
96 | } else if (iter_is_iovec(i)) { | |
a6294593 | 97 | size_t count = min(size, iov_iter_count(i)); |
8409a0d2 AV |
98 | const struct iovec *p; |
99 | size_t skip; | |
100 | ||
a6294593 | 101 | size -= count; |
de4f5fed | 102 | for (p = iter_iov(i), skip = i->iov_offset; count; p++, skip = 0) { |
a6294593 AG |
103 | size_t len = min(count, p->iov_len - skip); |
104 | size_t ret; | |
8409a0d2 AV |
105 | |
106 | if (unlikely(!len)) | |
107 | continue; | |
a6294593 AG |
108 | ret = fault_in_readable(p->iov_base + skip, len); |
109 | count -= len - ret; | |
110 | if (ret) | |
111 | break; | |
8409a0d2 | 112 | } |
a6294593 | 113 | return count + size; |
171a0203 AA |
114 | } |
115 | return 0; | |
116 | } | |
a6294593 | 117 | EXPORT_SYMBOL(fault_in_iov_iter_readable); |
171a0203 | 118 | |
cdd591fc AG |
119 | /* |
120 | * fault_in_iov_iter_writeable - fault in iov iterator for writing | |
121 | * @i: iterator | |
122 | * @size: maximum length | |
123 | * | |
124 | * Faults in the iterator using get_user_pages(), i.e., without triggering | |
125 | * hardware page faults. This is primarily useful when we already know that | |
126 | * some or all of the pages in @i aren't in memory. | |
127 | * | |
128 | * Returns the number of bytes not faulted in, like copy_to_user() and | |
129 | * copy_from_user(). | |
130 | * | |
131 | * Always returns 0 for non-user-space iterators. | |
132 | */ | |
133 | size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t size) | |
134 | { | |
fcb14cb1 AV |
135 | if (iter_is_ubuf(i)) { |
136 | size_t n = min(size, iov_iter_count(i)); | |
137 | n -= fault_in_safe_writeable(i->ubuf + i->iov_offset, n); | |
138 | return size - n; | |
139 | } else if (iter_is_iovec(i)) { | |
cdd591fc AG |
140 | size_t count = min(size, iov_iter_count(i)); |
141 | const struct iovec *p; | |
142 | size_t skip; | |
143 | ||
144 | size -= count; | |
de4f5fed | 145 | for (p = iter_iov(i), skip = i->iov_offset; count; p++, skip = 0) { |
cdd591fc AG |
146 | size_t len = min(count, p->iov_len - skip); |
147 | size_t ret; | |
148 | ||
149 | if (unlikely(!len)) | |
150 | continue; | |
151 | ret = fault_in_safe_writeable(p->iov_base + skip, len); | |
152 | count -= len - ret; | |
153 | if (ret) | |
154 | break; | |
155 | } | |
156 | return count + size; | |
157 | } | |
158 | return 0; | |
159 | } | |
160 | EXPORT_SYMBOL(fault_in_iov_iter_writeable); | |
161 | ||
aa563d7b | 162 | void iov_iter_init(struct iov_iter *i, unsigned int direction, |
71d8e532 AV |
163 | const struct iovec *iov, unsigned long nr_segs, |
164 | size_t count) | |
165 | { | |
aa563d7b | 166 | WARN_ON(direction & ~(READ | WRITE)); |
8cd54c1c AV |
167 | *i = (struct iov_iter) { |
168 | .iter_type = ITER_IOVEC, | |
3337ab08 | 169 | .nofault = false, |
8cd54c1c | 170 | .data_source = direction, |
de4f5fed | 171 | .__iov = iov, |
8cd54c1c AV |
172 | .nr_segs = nr_segs, |
173 | .iov_offset = 0, | |
174 | .count = count | |
175 | }; | |
71d8e532 AV |
176 | } |
177 | EXPORT_SYMBOL(iov_iter_init); | |
7b2c99d1 | 178 | |
aa28de27 | 179 | size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i) |
62a8067a | 180 | { |
a41dad90 AV |
181 | if (WARN_ON_ONCE(i->data_source)) |
182 | return 0; | |
fcb14cb1 | 183 | if (user_backed_iter(i)) |
09fc68dc | 184 | might_fault(); |
f1982740 DH |
185 | return iterate_and_advance(i, bytes, (void *)addr, |
186 | copy_to_user_iter, memcpy_to_iter); | |
c35e0248 | 187 | } |
aa28de27 | 188 | EXPORT_SYMBOL(_copy_to_iter); |
c35e0248 | 189 | |
ec6347bb | 190 | #ifdef CONFIG_ARCH_HAS_COPY_MC |
f1982740 DH |
191 | static __always_inline |
192 | size_t copy_to_user_iter_mc(void __user *iter_to, size_t progress, | |
193 | size_t len, void *from, void *priv2) | |
8780356e | 194 | { |
f1982740 DH |
195 | if (access_ok(iter_to, len)) { |
196 | from += progress; | |
197 | instrument_copy_to_user(iter_to, from, len); | |
198 | len = copy_mc_to_user(iter_to, from, len); | |
8780356e | 199 | } |
f1982740 DH |
200 | return len; |
201 | } | |
202 | ||
203 | static __always_inline | |
204 | size_t memcpy_to_iter_mc(void *iter_to, size_t progress, | |
205 | size_t len, void *from, void *priv2) | |
206 | { | |
207 | return copy_mc_to_kernel(iter_to, from + progress, len); | |
8780356e DW |
208 | } |
209 | ||
bf3eeb9b | 210 | /** |
ec6347bb | 211 | * _copy_mc_to_iter - copy to iter with source memory error exception handling |
bf3eeb9b DW |
212 | * @addr: source kernel address |
213 | * @bytes: total transfer length | |
44e55997 | 214 | * @i: destination iterator |
bf3eeb9b | 215 | * |
ec6347bb DW |
216 | * The pmem driver deploys this for the dax operation |
217 | * (dax_copy_to_iter()) for dax reads (bypass page-cache and the | |
218 | * block-layer). Upon #MC read(2) aborts and returns EIO or the bytes | |
219 | * successfully copied. | |
bf3eeb9b | 220 | * |
ec6347bb | 221 | * The main differences between this and typical _copy_to_iter(). |
bf3eeb9b DW |
222 | * |
223 | * * Typical tail/residue handling after a fault retries the copy | |
224 | * byte-by-byte until the fault happens again. Re-triggering machine | |
225 | * checks is potentially fatal so the implementation uses source | |
226 | * alignment and poison alignment assumptions to avoid re-triggering | |
227 | * hardware exceptions. | |
228 | * | |
3fc40265 DH |
229 | * * ITER_KVEC and ITER_BVEC can return short copies. Compare to |
230 | * copy_to_iter() where only ITER_IOVEC attempts might return a short copy. | |
44e55997 RD |
231 | * |
232 | * Return: number of bytes copied (may be %0) | |
bf3eeb9b | 233 | */ |
ec6347bb | 234 | size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i) |
8780356e | 235 | { |
a41dad90 AV |
236 | if (WARN_ON_ONCE(i->data_source)) |
237 | return 0; | |
fcb14cb1 | 238 | if (user_backed_iter(i)) |
8780356e | 239 | might_fault(); |
f1982740 DH |
240 | return iterate_and_advance(i, bytes, (void *)addr, |
241 | copy_to_user_iter_mc, memcpy_to_iter_mc); | |
8780356e | 242 | } |
ec6347bb DW |
243 | EXPORT_SYMBOL_GPL(_copy_mc_to_iter); |
244 | #endif /* CONFIG_ARCH_HAS_COPY_MC */ | |
8780356e | 245 | |
c9eec08b DH |
246 | static __always_inline |
247 | size_t __copy_from_iter(void *addr, size_t bytes, struct iov_iter *i) | |
248 | { | |
c9eec08b DH |
249 | return iterate_and_advance(i, bytes, addr, |
250 | copy_from_user_iter, memcpy_from_iter); | |
245f0922 KW |
251 | } |
252 | ||
aa28de27 | 253 | size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i) |
c35e0248 | 254 | { |
a41dad90 | 255 | if (WARN_ON_ONCE(!i->data_source)) |
241699cd | 256 | return 0; |
a41dad90 | 257 | |
fcb14cb1 | 258 | if (user_backed_iter(i)) |
09fc68dc | 259 | might_fault(); |
c9eec08b | 260 | return __copy_from_iter(addr, bytes, i); |
c35e0248 | 261 | } |
aa28de27 | 262 | EXPORT_SYMBOL(_copy_from_iter); |
c35e0248 | 263 | |
f1982740 DH |
264 | static __always_inline |
265 | size_t copy_from_user_iter_nocache(void __user *iter_from, size_t progress, | |
266 | size_t len, void *to, void *priv2) | |
267 | { | |
268 | return __copy_from_user_inatomic_nocache(to + progress, iter_from, len); | |
269 | } | |
270 | ||
aa28de27 | 271 | size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i) |
aa583096 | 272 | { |
a41dad90 | 273 | if (WARN_ON_ONCE(!i->data_source)) |
241699cd | 274 | return 0; |
a41dad90 | 275 | |
f1982740 DH |
276 | return iterate_and_advance(i, bytes, addr, |
277 | copy_from_user_iter_nocache, | |
278 | memcpy_from_iter); | |
aa583096 | 279 | } |
aa28de27 | 280 | EXPORT_SYMBOL(_copy_from_iter_nocache); |
aa583096 | 281 | |
0aed55af | 282 | #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE |
f1982740 DH |
283 | static __always_inline |
284 | size_t copy_from_user_iter_flushcache(void __user *iter_from, size_t progress, | |
285 | size_t len, void *to, void *priv2) | |
286 | { | |
287 | return __copy_from_user_flushcache(to + progress, iter_from, len); | |
288 | } | |
289 | ||
290 | static __always_inline | |
291 | size_t memcpy_from_iter_flushcache(void *iter_from, size_t progress, | |
292 | size_t len, void *to, void *priv2) | |
293 | { | |
294 | memcpy_flushcache(to + progress, iter_from, len); | |
295 | return 0; | |
296 | } | |
297 | ||
abd08d7d DW |
298 | /** |
299 | * _copy_from_iter_flushcache - write destination through cpu cache | |
300 | * @addr: destination kernel address | |
301 | * @bytes: total transfer length | |
44e55997 | 302 | * @i: source iterator |
abd08d7d DW |
303 | * |
304 | * The pmem driver arranges for filesystem-dax to use this facility via | |
305 | * dax_copy_from_iter() for ensuring that writes to persistent memory | |
306 | * are flushed through the CPU cache. It is differentiated from | |
307 | * _copy_from_iter_nocache() in that guarantees all data is flushed for | |
308 | * all iterator types. The _copy_from_iter_nocache() only attempts to | |
309 | * bypass the cache for the ITER_IOVEC case, and on some archs may use | |
310 | * instructions that strand dirty-data in the cache. | |
44e55997 RD |
311 | * |
312 | * Return: number of bytes copied (may be %0) | |
abd08d7d | 313 | */ |
6a37e940 | 314 | size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i) |
0aed55af | 315 | { |
a41dad90 | 316 | if (WARN_ON_ONCE(!i->data_source)) |
0aed55af | 317 | return 0; |
a41dad90 | 318 | |
f1982740 DH |
319 | return iterate_and_advance(i, bytes, addr, |
320 | copy_from_user_iter_flushcache, | |
321 | memcpy_from_iter_flushcache); | |
0aed55af | 322 | } |
6a37e940 | 323 | EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache); |
0aed55af DW |
324 | #endif |
325 | ||
72e809ed AV |
326 | static inline bool page_copy_sane(struct page *page, size_t offset, size_t n) |
327 | { | |
6daef95b ED |
328 | struct page *head; |
329 | size_t v = n + offset; | |
330 | ||
331 | /* | |
332 | * The general case needs to access the page order in order | |
333 | * to compute the page size. | |
334 | * However, we mostly deal with order-0 pages and thus can | |
335 | * avoid a possible cache line miss for requests that fit all | |
336 | * page orders. | |
337 | */ | |
338 | if (n <= v && v <= PAGE_SIZE) | |
339 | return true; | |
340 | ||
341 | head = compound_head(page); | |
342 | v += (page - head) << PAGE_SHIFT; | |
a90bcb86 | 343 | |
40a86061 AV |
344 | if (WARN_ON(n > v || v > page_size(head))) |
345 | return false; | |
346 | return true; | |
72e809ed | 347 | } |
cbbd26b8 | 348 | |
08aa6479 AV |
349 | size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, |
350 | struct iov_iter *i) | |
351 | { | |
352 | size_t res = 0; | |
40a86061 | 353 | if (!page_copy_sane(page, offset, bytes)) |
08aa6479 | 354 | return 0; |
a41dad90 AV |
355 | if (WARN_ON_ONCE(i->data_source)) |
356 | return 0; | |
08aa6479 AV |
357 | page += offset / PAGE_SIZE; // first subpage |
358 | offset %= PAGE_SIZE; | |
359 | while (1) { | |
f0f6b614 AV |
360 | void *kaddr = kmap_local_page(page); |
361 | size_t n = min(bytes, (size_t)PAGE_SIZE - offset); | |
362 | n = _copy_to_iter(kaddr + offset, n, i); | |
363 | kunmap_local(kaddr); | |
08aa6479 AV |
364 | res += n; |
365 | bytes -= n; | |
366 | if (!bytes || !n) | |
367 | break; | |
368 | offset += n; | |
369 | if (offset == PAGE_SIZE) { | |
370 | page++; | |
371 | offset = 0; | |
372 | } | |
373 | } | |
374 | return res; | |
375 | } | |
62a8067a AV |
376 | EXPORT_SYMBOL(copy_page_to_iter); |
377 | ||
4f80818b LS |
378 | size_t copy_page_to_iter_nofault(struct page *page, unsigned offset, size_t bytes, |
379 | struct iov_iter *i) | |
380 | { | |
381 | size_t res = 0; | |
382 | ||
383 | if (!page_copy_sane(page, offset, bytes)) | |
384 | return 0; | |
385 | if (WARN_ON_ONCE(i->data_source)) | |
386 | return 0; | |
4f80818b LS |
387 | page += offset / PAGE_SIZE; // first subpage |
388 | offset %= PAGE_SIZE; | |
389 | while (1) { | |
390 | void *kaddr = kmap_local_page(page); | |
391 | size_t n = min(bytes, (size_t)PAGE_SIZE - offset); | |
392 | ||
fe2c34ba | 393 | n = iterate_and_advance(i, n, kaddr + offset, |
f1982740 DH |
394 | copy_to_user_iter_nofault, |
395 | memcpy_to_iter); | |
4f80818b LS |
396 | kunmap_local(kaddr); |
397 | res += n; | |
398 | bytes -= n; | |
399 | if (!bytes || !n) | |
400 | break; | |
401 | offset += n; | |
402 | if (offset == PAGE_SIZE) { | |
403 | page++; | |
404 | offset = 0; | |
405 | } | |
406 | } | |
407 | return res; | |
408 | } | |
409 | EXPORT_SYMBOL(copy_page_to_iter_nofault); | |
410 | ||
62a8067a AV |
411 | size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, |
412 | struct iov_iter *i) | |
413 | { | |
c03f05f1 AV |
414 | size_t res = 0; |
415 | if (!page_copy_sane(page, offset, bytes)) | |
416 | return 0; | |
417 | page += offset / PAGE_SIZE; // first subpage | |
418 | offset %= PAGE_SIZE; | |
419 | while (1) { | |
55ca375c | 420 | void *kaddr = kmap_local_page(page); |
c03f05f1 AV |
421 | size_t n = min(bytes, (size_t)PAGE_SIZE - offset); |
422 | n = _copy_from_iter(kaddr + offset, n, i); | |
55ca375c | 423 | kunmap_local(kaddr); |
c03f05f1 AV |
424 | res += n; |
425 | bytes -= n; | |
426 | if (!bytes || !n) | |
427 | break; | |
428 | offset += n; | |
429 | if (offset == PAGE_SIZE) { | |
430 | page++; | |
431 | offset = 0; | |
432 | } | |
28f38db7 | 433 | } |
c03f05f1 | 434 | return res; |
62a8067a AV |
435 | } |
436 | EXPORT_SYMBOL(copy_page_from_iter); | |
437 | ||
f1982740 DH |
438 | static __always_inline |
439 | size_t zero_to_user_iter(void __user *iter_to, size_t progress, | |
440 | size_t len, void *priv, void *priv2) | |
c35e0248 | 441 | { |
f1982740 DH |
442 | return clear_user(iter_to, len); |
443 | } | |
8442fa46 | 444 | |
f1982740 DH |
445 | static __always_inline |
446 | size_t zero_to_iter(void *iter_to, size_t progress, | |
447 | size_t len, void *priv, void *priv2) | |
448 | { | |
449 | memset(iter_to, 0, len); | |
450 | return 0; | |
451 | } | |
452 | ||
453 | size_t iov_iter_zero(size_t bytes, struct iov_iter *i) | |
454 | { | |
455 | return iterate_and_advance(i, bytes, NULL, | |
456 | zero_to_user_iter, zero_to_iter); | |
c35e0248 MW |
457 | } |
458 | EXPORT_SYMBOL(iov_iter_zero); | |
459 | ||
1b030698 | 460 | size_t copy_page_from_iter_atomic(struct page *page, size_t offset, |
908a1ad8 | 461 | size_t bytes, struct iov_iter *i) |
62a8067a | 462 | { |
908a1ad8 | 463 | size_t n, copied = 0; |
f7f9a0c8 MWO |
464 | |
465 | if (!page_copy_sane(page, offset, bytes)) | |
72e809ed | 466 | return 0; |
f7f9a0c8 | 467 | if (WARN_ON_ONCE(!i->data_source)) |
241699cd | 468 | return 0; |
f7f9a0c8 | 469 | |
908a1ad8 MWO |
470 | do { |
471 | char *p; | |
f7f9a0c8 | 472 | |
908a1ad8 MWO |
473 | n = bytes - copied; |
474 | if (PageHighMem(page)) { | |
475 | page += offset / PAGE_SIZE; | |
476 | offset %= PAGE_SIZE; | |
477 | n = min_t(size_t, n, PAGE_SIZE - offset); | |
478 | } | |
479 | ||
480 | p = kmap_atomic(page) + offset; | |
c9eec08b | 481 | n = __copy_from_iter(p, n, i); |
908a1ad8 MWO |
482 | kunmap_atomic(p); |
483 | copied += n; | |
484 | offset += n; | |
485 | } while (PageHighMem(page) && copied != bytes && n > 0); | |
486 | ||
487 | return copied; | |
62a8067a | 488 | } |
f0b65f39 | 489 | EXPORT_SYMBOL(copy_page_from_iter_atomic); |
62a8067a | 490 | |
54c8195b PB |
491 | static void iov_iter_bvec_advance(struct iov_iter *i, size_t size) |
492 | { | |
18fa9af7 | 493 | const struct bio_vec *bvec, *end; |
54c8195b | 494 | |
18fa9af7 AV |
495 | if (!i->count) |
496 | return; | |
497 | i->count -= size; | |
498 | ||
499 | size += i->iov_offset; | |
54c8195b | 500 | |
18fa9af7 AV |
501 | for (bvec = i->bvec, end = bvec + i->nr_segs; bvec < end; bvec++) { |
502 | if (likely(size < bvec->bv_len)) | |
503 | break; | |
504 | size -= bvec->bv_len; | |
505 | } | |
506 | i->iov_offset = size; | |
507 | i->nr_segs -= bvec - i->bvec; | |
508 | i->bvec = bvec; | |
54c8195b PB |
509 | } |
510 | ||
185ac4d4 AV |
511 | static void iov_iter_iovec_advance(struct iov_iter *i, size_t size) |
512 | { | |
513 | const struct iovec *iov, *end; | |
514 | ||
515 | if (!i->count) | |
516 | return; | |
517 | i->count -= size; | |
518 | ||
519 | size += i->iov_offset; // from beginning of current segment | |
de4f5fed | 520 | for (iov = iter_iov(i), end = iov + i->nr_segs; iov < end; iov++) { |
185ac4d4 AV |
521 | if (likely(size < iov->iov_len)) |
522 | break; | |
523 | size -= iov->iov_len; | |
524 | } | |
525 | i->iov_offset = size; | |
de4f5fed JA |
526 | i->nr_segs -= iov - iter_iov(i); |
527 | i->__iov = iov; | |
185ac4d4 AV |
528 | } |
529 | ||
62a8067a AV |
530 | void iov_iter_advance(struct iov_iter *i, size_t size) |
531 | { | |
3b3fc051 AV |
532 | if (unlikely(i->count < size)) |
533 | size = i->count; | |
fcb14cb1 AV |
534 | if (likely(iter_is_ubuf(i)) || unlikely(iov_iter_is_xarray(i))) { |
535 | i->iov_offset += size; | |
536 | i->count -= size; | |
537 | } else if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) { | |
185ac4d4 AV |
538 | /* iovec and kvec have identical layouts */ |
539 | iov_iter_iovec_advance(i, size); | |
540 | } else if (iov_iter_is_bvec(i)) { | |
541 | iov_iter_bvec_advance(i, size); | |
185ac4d4 AV |
542 | } else if (iov_iter_is_discard(i)) { |
543 | i->count -= size; | |
54c8195b | 544 | } |
62a8067a AV |
545 | } |
546 | EXPORT_SYMBOL(iov_iter_advance); | |
547 | ||
27c0e374 AV |
548 | void iov_iter_revert(struct iov_iter *i, size_t unroll) |
549 | { | |
550 | if (!unroll) | |
551 | return; | |
5b47d59a AV |
552 | if (WARN_ON(unroll > MAX_RW_COUNT)) |
553 | return; | |
27c0e374 | 554 | i->count += unroll; |
9ea9ce04 DH |
555 | if (unlikely(iov_iter_is_discard(i))) |
556 | return; | |
27c0e374 AV |
557 | if (unroll <= i->iov_offset) { |
558 | i->iov_offset -= unroll; | |
559 | return; | |
560 | } | |
561 | unroll -= i->iov_offset; | |
fcb14cb1 | 562 | if (iov_iter_is_xarray(i) || iter_is_ubuf(i)) { |
7ff50620 DH |
563 | BUG(); /* We should never go beyond the start of the specified |
564 | * range since we might then be straying into pages that | |
565 | * aren't pinned. | |
566 | */ | |
567 | } else if (iov_iter_is_bvec(i)) { | |
27c0e374 AV |
568 | const struct bio_vec *bvec = i->bvec; |
569 | while (1) { | |
570 | size_t n = (--bvec)->bv_len; | |
571 | i->nr_segs++; | |
572 | if (unroll <= n) { | |
573 | i->bvec = bvec; | |
574 | i->iov_offset = n - unroll; | |
575 | return; | |
576 | } | |
577 | unroll -= n; | |
578 | } | |
579 | } else { /* same logics for iovec and kvec */ | |
de4f5fed | 580 | const struct iovec *iov = iter_iov(i); |
27c0e374 AV |
581 | while (1) { |
582 | size_t n = (--iov)->iov_len; | |
583 | i->nr_segs++; | |
584 | if (unroll <= n) { | |
de4f5fed | 585 | i->__iov = iov; |
27c0e374 AV |
586 | i->iov_offset = n - unroll; |
587 | return; | |
588 | } | |
589 | unroll -= n; | |
590 | } | |
591 | } | |
592 | } | |
593 | EXPORT_SYMBOL(iov_iter_revert); | |
594 | ||
62a8067a AV |
595 | /* |
596 | * Return the count of just the current iov_iter segment. | |
597 | */ | |
598 | size_t iov_iter_single_seg_count(const struct iov_iter *i) | |
599 | { | |
28f38db7 AV |
600 | if (i->nr_segs > 1) { |
601 | if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) | |
de4f5fed | 602 | return min(i->count, iter_iov(i)->iov_len - i->iov_offset); |
28f38db7 AV |
603 | if (iov_iter_is_bvec(i)) |
604 | return min(i->count, i->bvec->bv_len - i->iov_offset); | |
605 | } | |
606 | return i->count; | |
62a8067a AV |
607 | } |
608 | EXPORT_SYMBOL(iov_iter_single_seg_count); | |
609 | ||
aa563d7b | 610 | void iov_iter_kvec(struct iov_iter *i, unsigned int direction, |
05afcb77 | 611 | const struct kvec *kvec, unsigned long nr_segs, |
abb78f87 AV |
612 | size_t count) |
613 | { | |
aa563d7b | 614 | WARN_ON(direction & ~(READ | WRITE)); |
8cd54c1c AV |
615 | *i = (struct iov_iter){ |
616 | .iter_type = ITER_KVEC, | |
617 | .data_source = direction, | |
618 | .kvec = kvec, | |
619 | .nr_segs = nr_segs, | |
620 | .iov_offset = 0, | |
621 | .count = count | |
622 | }; | |
abb78f87 AV |
623 | } |
624 | EXPORT_SYMBOL(iov_iter_kvec); | |
625 | ||
aa563d7b | 626 | void iov_iter_bvec(struct iov_iter *i, unsigned int direction, |
05afcb77 AV |
627 | const struct bio_vec *bvec, unsigned long nr_segs, |
628 | size_t count) | |
629 | { | |
aa563d7b | 630 | WARN_ON(direction & ~(READ | WRITE)); |
8cd54c1c AV |
631 | *i = (struct iov_iter){ |
632 | .iter_type = ITER_BVEC, | |
633 | .data_source = direction, | |
634 | .bvec = bvec, | |
635 | .nr_segs = nr_segs, | |
636 | .iov_offset = 0, | |
637 | .count = count | |
638 | }; | |
05afcb77 AV |
639 | } |
640 | EXPORT_SYMBOL(iov_iter_bvec); | |
641 | ||
7ff50620 DH |
642 | /** |
643 | * iov_iter_xarray - Initialise an I/O iterator to use the pages in an xarray | |
644 | * @i: The iterator to initialise. | |
645 | * @direction: The direction of the transfer. | |
646 | * @xarray: The xarray to access. | |
647 | * @start: The start file position. | |
648 | * @count: The size of the I/O buffer in bytes. | |
649 | * | |
650 | * Set up an I/O iterator to either draw data out of the pages attached to an | |
651 | * inode or to inject data into those pages. The pages *must* be prevented | |
652 | * from evaporation, either by taking a ref on them or locking them by the | |
653 | * caller. | |
654 | */ | |
655 | void iov_iter_xarray(struct iov_iter *i, unsigned int direction, | |
656 | struct xarray *xarray, loff_t start, size_t count) | |
657 | { | |
658 | BUG_ON(direction & ~1); | |
8cd54c1c AV |
659 | *i = (struct iov_iter) { |
660 | .iter_type = ITER_XARRAY, | |
661 | .data_source = direction, | |
662 | .xarray = xarray, | |
663 | .xarray_start = start, | |
664 | .count = count, | |
665 | .iov_offset = 0 | |
666 | }; | |
7ff50620 DH |
667 | } |
668 | EXPORT_SYMBOL(iov_iter_xarray); | |
669 | ||
9ea9ce04 DH |
670 | /** |
671 | * iov_iter_discard - Initialise an I/O iterator that discards data | |
672 | * @i: The iterator to initialise. | |
673 | * @direction: The direction of the transfer. | |
674 | * @count: The size of the I/O buffer in bytes. | |
675 | * | |
676 | * Set up an I/O iterator that just discards everything that's written to it. | |
677 | * It's only available as a READ iterator. | |
678 | */ | |
679 | void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count) | |
680 | { | |
681 | BUG_ON(direction != READ); | |
8cd54c1c AV |
682 | *i = (struct iov_iter){ |
683 | .iter_type = ITER_DISCARD, | |
684 | .data_source = false, | |
685 | .count = count, | |
686 | .iov_offset = 0 | |
687 | }; | |
9ea9ce04 DH |
688 | } |
689 | EXPORT_SYMBOL(iov_iter_discard); | |
690 | ||
cfa320f7 KB |
691 | static bool iov_iter_aligned_iovec(const struct iov_iter *i, unsigned addr_mask, |
692 | unsigned len_mask) | |
693 | { | |
2263639f | 694 | const struct iovec *iov = iter_iov(i); |
cfa320f7 KB |
695 | size_t size = i->count; |
696 | size_t skip = i->iov_offset; | |
cfa320f7 | 697 | |
2263639f | 698 | do { |
de4f5fed | 699 | size_t len = iov->iov_len - skip; |
cfa320f7 KB |
700 | |
701 | if (len > size) | |
702 | len = size; | |
703 | if (len & len_mask) | |
704 | return false; | |
de4f5fed | 705 | if ((unsigned long)(iov->iov_base + skip) & addr_mask) |
cfa320f7 KB |
706 | return false; |
707 | ||
2263639f | 708 | iov++; |
cfa320f7 | 709 | size -= len; |
2263639f JA |
710 | skip = 0; |
711 | } while (size); | |
712 | ||
cfa320f7 KB |
713 | return true; |
714 | } | |
715 | ||
716 | static bool iov_iter_aligned_bvec(const struct iov_iter *i, unsigned addr_mask, | |
717 | unsigned len_mask) | |
718 | { | |
2263639f | 719 | const struct bio_vec *bvec = i->bvec; |
cfa320f7 | 720 | unsigned skip = i->iov_offset; |
2263639f | 721 | size_t size = i->count; |
cfa320f7 | 722 | |
2263639f JA |
723 | do { |
724 | size_t len = bvec->bv_len; | |
cfa320f7 KB |
725 | |
726 | if (len > size) | |
727 | len = size; | |
728 | if (len & len_mask) | |
729 | return false; | |
2263639f | 730 | if ((unsigned long)(bvec->bv_offset + skip) & addr_mask) |
cfa320f7 KB |
731 | return false; |
732 | ||
2263639f | 733 | bvec++; |
cfa320f7 | 734 | size -= len; |
2263639f JA |
735 | skip = 0; |
736 | } while (size); | |
737 | ||
cfa320f7 KB |
738 | return true; |
739 | } | |
740 | ||
741 | /** | |
742 | * iov_iter_is_aligned() - Check if the addresses and lengths of each segments | |
743 | * are aligned to the parameters. | |
744 | * | |
745 | * @i: &struct iov_iter to restore | |
746 | * @addr_mask: bit mask to check against the iov element's addresses | |
747 | * @len_mask: bit mask to check against the iov element's lengths | |
748 | * | |
749 | * Return: false if any addresses or lengths intersect with the provided masks | |
750 | */ | |
751 | bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask, | |
752 | unsigned len_mask) | |
753 | { | |
fcb14cb1 AV |
754 | if (likely(iter_is_ubuf(i))) { |
755 | if (i->count & len_mask) | |
756 | return false; | |
757 | if ((unsigned long)(i->ubuf + i->iov_offset) & addr_mask) | |
758 | return false; | |
759 | return true; | |
760 | } | |
761 | ||
cfa320f7 KB |
762 | if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) |
763 | return iov_iter_aligned_iovec(i, addr_mask, len_mask); | |
764 | ||
765 | if (iov_iter_is_bvec(i)) | |
766 | return iov_iter_aligned_bvec(i, addr_mask, len_mask); | |
767 | ||
cfa320f7 KB |
768 | if (iov_iter_is_xarray(i)) { |
769 | if (i->count & len_mask) | |
770 | return false; | |
771 | if ((i->xarray_start + i->iov_offset) & addr_mask) | |
772 | return false; | |
773 | } | |
774 | ||
775 | return true; | |
776 | } | |
777 | EXPORT_SYMBOL_GPL(iov_iter_is_aligned); | |
778 | ||
9221d2e3 | 779 | static unsigned long iov_iter_alignment_iovec(const struct iov_iter *i) |
62a8067a | 780 | { |
2263639f | 781 | const struct iovec *iov = iter_iov(i); |
04a31165 AV |
782 | unsigned long res = 0; |
783 | size_t size = i->count; | |
9221d2e3 | 784 | size_t skip = i->iov_offset; |
9221d2e3 | 785 | |
2263639f | 786 | do { |
de4f5fed | 787 | size_t len = iov->iov_len - skip; |
9221d2e3 | 788 | if (len) { |
de4f5fed | 789 | res |= (unsigned long)iov->iov_base + skip; |
9221d2e3 AV |
790 | if (len > size) |
791 | len = size; | |
792 | res |= len; | |
793 | size -= len; | |
9221d2e3 | 794 | } |
2263639f JA |
795 | iov++; |
796 | skip = 0; | |
797 | } while (size); | |
9221d2e3 AV |
798 | return res; |
799 | } | |
04a31165 | 800 | |
9221d2e3 AV |
801 | static unsigned long iov_iter_alignment_bvec(const struct iov_iter *i) |
802 | { | |
2263639f | 803 | const struct bio_vec *bvec = i->bvec; |
9221d2e3 AV |
804 | unsigned res = 0; |
805 | size_t size = i->count; | |
806 | unsigned skip = i->iov_offset; | |
9221d2e3 | 807 | |
2263639f JA |
808 | do { |
809 | size_t len = bvec->bv_len - skip; | |
810 | res |= (unsigned long)bvec->bv_offset + skip; | |
9221d2e3 AV |
811 | if (len > size) |
812 | len = size; | |
813 | res |= len; | |
2263639f | 814 | bvec++; |
9221d2e3 | 815 | size -= len; |
2263639f JA |
816 | skip = 0; |
817 | } while (size); | |
818 | ||
9221d2e3 AV |
819 | return res; |
820 | } | |
821 | ||
822 | unsigned long iov_iter_alignment(const struct iov_iter *i) | |
823 | { | |
fcb14cb1 AV |
824 | if (likely(iter_is_ubuf(i))) { |
825 | size_t size = i->count; | |
826 | if (size) | |
827 | return ((unsigned long)i->ubuf + i->iov_offset) | size; | |
828 | return 0; | |
829 | } | |
830 | ||
9221d2e3 AV |
831 | /* iovec and kvec have identical layouts */ |
832 | if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) | |
833 | return iov_iter_alignment_iovec(i); | |
834 | ||
835 | if (iov_iter_is_bvec(i)) | |
836 | return iov_iter_alignment_bvec(i); | |
837 | ||
9221d2e3 | 838 | if (iov_iter_is_xarray(i)) |
3d14ec1f | 839 | return (i->xarray_start + i->iov_offset) | i->count; |
9221d2e3 AV |
840 | |
841 | return 0; | |
62a8067a AV |
842 | } |
843 | EXPORT_SYMBOL(iov_iter_alignment); | |
844 | ||
357f435d AV |
845 | unsigned long iov_iter_gap_alignment(const struct iov_iter *i) |
846 | { | |
33844e66 | 847 | unsigned long res = 0; |
610c7a71 | 848 | unsigned long v = 0; |
357f435d | 849 | size_t size = i->count; |
610c7a71 | 850 | unsigned k; |
357f435d | 851 | |
fcb14cb1 AV |
852 | if (iter_is_ubuf(i)) |
853 | return 0; | |
854 | ||
610c7a71 | 855 | if (WARN_ON(!iter_is_iovec(i))) |
241699cd | 856 | return ~0U; |
241699cd | 857 | |
610c7a71 | 858 | for (k = 0; k < i->nr_segs; k++) { |
de4f5fed JA |
859 | const struct iovec *iov = iter_iov(i) + k; |
860 | if (iov->iov_len) { | |
861 | unsigned long base = (unsigned long)iov->iov_base; | |
610c7a71 AV |
862 | if (v) // if not the first one |
863 | res |= base | v; // this start | previous end | |
de4f5fed JA |
864 | v = base + iov->iov_len; |
865 | if (size <= iov->iov_len) | |
610c7a71 | 866 | break; |
de4f5fed | 867 | size -= iov->iov_len; |
610c7a71 AV |
868 | } |
869 | } | |
33844e66 | 870 | return res; |
357f435d AV |
871 | } |
872 | EXPORT_SYMBOL(iov_iter_gap_alignment); | |
873 | ||
3cf42da3 AV |
874 | static int want_pages_array(struct page ***res, size_t size, |
875 | size_t start, unsigned int maxpages) | |
acbdeb83 | 876 | { |
3cf42da3 AV |
877 | unsigned int count = DIV_ROUND_UP(size + start, PAGE_SIZE); |
878 | ||
879 | if (count > maxpages) | |
880 | count = maxpages; | |
881 | WARN_ON(!count); // caller should've prevented that | |
882 | if (!*res) { | |
883 | *res = kvmalloc_array(count, sizeof(struct page *), GFP_KERNEL); | |
884 | if (!*res) | |
885 | return 0; | |
886 | } | |
887 | return count; | |
acbdeb83 AV |
888 | } |
889 | ||
7ff50620 DH |
890 | static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa, |
891 | pgoff_t index, unsigned int nr_pages) | |
892 | { | |
893 | XA_STATE(xas, xa, index); | |
894 | struct page *page; | |
895 | unsigned int ret = 0; | |
896 | ||
897 | rcu_read_lock(); | |
898 | for (page = xas_load(&xas); page; page = xas_next(&xas)) { | |
899 | if (xas_retry(&xas, page)) | |
900 | continue; | |
901 | ||
902 | /* Has the page moved or been split? */ | |
903 | if (unlikely(page != xas_reload(&xas))) { | |
904 | xas_reset(&xas); | |
905 | continue; | |
906 | } | |
907 | ||
908 | pages[ret] = find_subpage(page, xas.xa_index); | |
909 | get_page(pages[ret]); | |
910 | if (++ret == nr_pages) | |
911 | break; | |
912 | } | |
913 | rcu_read_unlock(); | |
914 | return ret; | |
915 | } | |
916 | ||
917 | static ssize_t iter_xarray_get_pages(struct iov_iter *i, | |
68fe506f | 918 | struct page ***pages, size_t maxsize, |
7ff50620 DH |
919 | unsigned maxpages, size_t *_start_offset) |
920 | { | |
3cf42da3 AV |
921 | unsigned nr, offset, count; |
922 | pgoff_t index; | |
7ff50620 DH |
923 | loff_t pos; |
924 | ||
7ff50620 DH |
925 | pos = i->xarray_start + i->iov_offset; |
926 | index = pos >> PAGE_SHIFT; | |
927 | offset = pos & ~PAGE_MASK; | |
928 | *_start_offset = offset; | |
929 | ||
3cf42da3 AV |
930 | count = want_pages_array(pages, maxsize, offset, maxpages); |
931 | if (!count) | |
932 | return -ENOMEM; | |
68fe506f | 933 | nr = iter_xarray_populate_pages(*pages, i->xarray, index, count); |
7ff50620 DH |
934 | if (nr == 0) |
935 | return 0; | |
936 | ||
eba2d3d7 | 937 | maxsize = min_t(size_t, nr * PAGE_SIZE - offset, maxsize); |
310d9d5a AV |
938 | i->iov_offset += maxsize; |
939 | i->count -= maxsize; | |
eba2d3d7 | 940 | return maxsize; |
7ff50620 DH |
941 | } |
942 | ||
fcb14cb1 | 943 | /* must be done on non-empty ITER_UBUF or ITER_IOVEC one */ |
dd45ab9d | 944 | static unsigned long first_iovec_segment(const struct iov_iter *i, size_t *size) |
3d671ca6 AV |
945 | { |
946 | size_t skip; | |
947 | long k; | |
948 | ||
fcb14cb1 AV |
949 | if (iter_is_ubuf(i)) |
950 | return (unsigned long)i->ubuf + i->iov_offset; | |
951 | ||
3d671ca6 | 952 | for (k = 0, skip = i->iov_offset; k < i->nr_segs; k++, skip = 0) { |
de4f5fed JA |
953 | const struct iovec *iov = iter_iov(i) + k; |
954 | size_t len = iov->iov_len - skip; | |
3d671ca6 AV |
955 | |
956 | if (unlikely(!len)) | |
957 | continue; | |
59dbd7d0 AV |
958 | if (*size > len) |
959 | *size = len; | |
de4f5fed | 960 | return (unsigned long)iov->iov_base + skip; |
3d671ca6 AV |
961 | } |
962 | BUG(); // if it had been empty, we wouldn't get called | |
963 | } | |
964 | ||
965 | /* must be done on non-empty ITER_BVEC one */ | |
966 | static struct page *first_bvec_segment(const struct iov_iter *i, | |
59dbd7d0 | 967 | size_t *size, size_t *start) |
3d671ca6 AV |
968 | { |
969 | struct page *page; | |
970 | size_t skip = i->iov_offset, len; | |
971 | ||
972 | len = i->bvec->bv_len - skip; | |
59dbd7d0 AV |
973 | if (*size > len) |
974 | *size = len; | |
3d671ca6 AV |
975 | skip += i->bvec->bv_offset; |
976 | page = i->bvec->bv_page + skip / PAGE_SIZE; | |
dda8e5d1 | 977 | *start = skip % PAGE_SIZE; |
3d671ca6 AV |
978 | return page; |
979 | } | |
980 | ||
451c0ba9 AV |
981 | static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i, |
982 | struct page ***pages, size_t maxsize, | |
84bd06c6 | 983 | unsigned int maxpages, size_t *start) |
62a8067a | 984 | { |
f62e52d1 | 985 | unsigned int n, gup_flags = 0; |
3d671ca6 | 986 | |
e5393fae AV |
987 | if (maxsize > i->count) |
988 | maxsize = i->count; | |
451c0ba9 | 989 | if (!maxsize) |
3d671ca6 | 990 | return 0; |
7392ed17 AV |
991 | if (maxsize > MAX_RW_COUNT) |
992 | maxsize = MAX_RW_COUNT; | |
e5393fae | 993 | |
fcb14cb1 | 994 | if (likely(user_backed_iter(i))) { |
3d671ca6 | 995 | unsigned long addr; |
3cf42da3 | 996 | int res; |
e5393fae | 997 | |
3337ab08 AG |
998 | if (iov_iter_rw(i) != WRITE) |
999 | gup_flags |= FOLL_WRITE; | |
1000 | if (i->nofault) | |
1001 | gup_flags |= FOLL_NOFAULT; | |
1002 | ||
dd45ab9d AV |
1003 | addr = first_iovec_segment(i, &maxsize); |
1004 | *start = addr % PAGE_SIZE; | |
1005 | addr &= PAGE_MASK; | |
3cf42da3 AV |
1006 | n = want_pages_array(pages, maxsize, *start, maxpages); |
1007 | if (!n) | |
1008 | return -ENOMEM; | |
451c0ba9 | 1009 | res = get_user_pages_fast(addr, n, gup_flags, *pages); |
814a6674 | 1010 | if (unlikely(res <= 0)) |
e5393fae | 1011 | return res; |
eba2d3d7 AV |
1012 | maxsize = min_t(size_t, maxsize, res * PAGE_SIZE - *start); |
1013 | iov_iter_advance(i, maxsize); | |
1014 | return maxsize; | |
3d671ca6 AV |
1015 | } |
1016 | if (iov_iter_is_bvec(i)) { | |
451c0ba9 | 1017 | struct page **p; |
3d671ca6 AV |
1018 | struct page *page; |
1019 | ||
59dbd7d0 | 1020 | page = first_bvec_segment(i, &maxsize, start); |
3cf42da3 AV |
1021 | n = want_pages_array(pages, maxsize, *start, maxpages); |
1022 | if (!n) | |
1023 | return -ENOMEM; | |
451c0ba9 | 1024 | p = *pages; |
dda8e5d1 | 1025 | for (int k = 0; k < n; k++) |
eba2d3d7 AV |
1026 | get_page(p[k] = page + k); |
1027 | maxsize = min_t(size_t, maxsize, n * PAGE_SIZE - *start); | |
310d9d5a AV |
1028 | i->count -= maxsize; |
1029 | i->iov_offset += maxsize; | |
1030 | if (i->iov_offset == i->bvec->bv_len) { | |
1031 | i->iov_offset = 0; | |
1032 | i->bvec++; | |
1033 | i->nr_segs--; | |
1034 | } | |
eba2d3d7 | 1035 | return maxsize; |
3d671ca6 | 1036 | } |
3d671ca6 | 1037 | if (iov_iter_is_xarray(i)) |
451c0ba9 | 1038 | return iter_xarray_get_pages(i, pages, maxsize, maxpages, start); |
3d671ca6 | 1039 | return -EFAULT; |
62a8067a | 1040 | } |
62a8067a | 1041 | |
84bd06c6 CH |
1042 | ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages, |
1043 | size_t maxsize, unsigned maxpages, size_t *start) | |
62a8067a | 1044 | { |
451c0ba9 | 1045 | if (!maxpages) |
3d671ca6 | 1046 | return 0; |
451c0ba9 | 1047 | BUG_ON(!pages); |
3d671ca6 | 1048 | |
84bd06c6 | 1049 | return __iov_iter_get_pages_alloc(i, &pages, maxsize, maxpages, start); |
62a8067a | 1050 | } |
eba2d3d7 | 1051 | EXPORT_SYMBOL(iov_iter_get_pages2); |
91329559 | 1052 | |
84bd06c6 CH |
1053 | ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, |
1054 | struct page ***pages, size_t maxsize, size_t *start) | |
91329559 AV |
1055 | { |
1056 | ssize_t len; | |
1057 | ||
1058 | *pages = NULL; | |
1059 | ||
84bd06c6 | 1060 | len = __iov_iter_get_pages_alloc(i, pages, maxsize, ~0U, start); |
91329559 AV |
1061 | if (len <= 0) { |
1062 | kvfree(*pages); | |
1063 | *pages = NULL; | |
1064 | } | |
1065 | return len; | |
1066 | } | |
eba2d3d7 | 1067 | EXPORT_SYMBOL(iov_iter_get_pages_alloc2); |
62a8067a | 1068 | |
66531c65 | 1069 | static int iov_npages(const struct iov_iter *i, int maxpages) |
62a8067a | 1070 | { |
66531c65 AV |
1071 | size_t skip = i->iov_offset, size = i->count; |
1072 | const struct iovec *p; | |
e0f2dc40 AV |
1073 | int npages = 0; |
1074 | ||
de4f5fed | 1075 | for (p = iter_iov(i); size; skip = 0, p++) { |
66531c65 AV |
1076 | unsigned offs = offset_in_page(p->iov_base + skip); |
1077 | size_t len = min(p->iov_len - skip, size); | |
e0f2dc40 | 1078 | |
66531c65 AV |
1079 | if (len) { |
1080 | size -= len; | |
1081 | npages += DIV_ROUND_UP(offs + len, PAGE_SIZE); | |
1082 | if (unlikely(npages > maxpages)) | |
1083 | return maxpages; | |
1084 | } | |
1085 | } | |
1086 | return npages; | |
1087 | } | |
1088 | ||
1089 | static int bvec_npages(const struct iov_iter *i, int maxpages) | |
1090 | { | |
1091 | size_t skip = i->iov_offset, size = i->count; | |
1092 | const struct bio_vec *p; | |
1093 | int npages = 0; | |
1094 | ||
1095 | for (p = i->bvec; size; skip = 0, p++) { | |
1096 | unsigned offs = (p->bv_offset + skip) % PAGE_SIZE; | |
1097 | size_t len = min(p->bv_len - skip, size); | |
1098 | ||
1099 | size -= len; | |
1100 | npages += DIV_ROUND_UP(offs + len, PAGE_SIZE); | |
1101 | if (unlikely(npages > maxpages)) | |
1102 | return maxpages; | |
1103 | } | |
1104 | return npages; | |
1105 | } | |
1106 | ||
1107 | int iov_iter_npages(const struct iov_iter *i, int maxpages) | |
1108 | { | |
1109 | if (unlikely(!i->count)) | |
1110 | return 0; | |
fcb14cb1 AV |
1111 | if (likely(iter_is_ubuf(i))) { |
1112 | unsigned offs = offset_in_page(i->ubuf + i->iov_offset); | |
1113 | int npages = DIV_ROUND_UP(offs + i->count, PAGE_SIZE); | |
1114 | return min(npages, maxpages); | |
1115 | } | |
66531c65 AV |
1116 | /* iovec and kvec have identical layouts */ |
1117 | if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) | |
1118 | return iov_npages(i, maxpages); | |
1119 | if (iov_iter_is_bvec(i)) | |
1120 | return bvec_npages(i, maxpages); | |
66531c65 | 1121 | if (iov_iter_is_xarray(i)) { |
e4f8df86 AV |
1122 | unsigned offset = (i->xarray_start + i->iov_offset) % PAGE_SIZE; |
1123 | int npages = DIV_ROUND_UP(offset + i->count, PAGE_SIZE); | |
66531c65 AV |
1124 | return min(npages, maxpages); |
1125 | } | |
1126 | return 0; | |
62a8067a | 1127 | } |
f67da30c | 1128 | EXPORT_SYMBOL(iov_iter_npages); |
4b8164b9 AV |
1129 | |
1130 | const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags) | |
1131 | { | |
1132 | *new = *old; | |
00e23707 | 1133 | if (iov_iter_is_bvec(new)) |
4b8164b9 AV |
1134 | return new->bvec = kmemdup(new->bvec, |
1135 | new->nr_segs * sizeof(struct bio_vec), | |
1136 | flags); | |
fcb14cb1 | 1137 | else if (iov_iter_is_kvec(new) || iter_is_iovec(new)) |
4b8164b9 | 1138 | /* iovec and kvec have identical layout */ |
de4f5fed | 1139 | return new->__iov = kmemdup(new->__iov, |
4b8164b9 AV |
1140 | new->nr_segs * sizeof(struct iovec), |
1141 | flags); | |
fcb14cb1 | 1142 | return NULL; |
4b8164b9 AV |
1143 | } |
1144 | EXPORT_SYMBOL(dup_iter); | |
bc917be8 | 1145 | |
50f9a76e | 1146 | static __noclone int copy_compat_iovec_from_user(struct iovec *iov, |
bd8c239c | 1147 | const struct iovec __user *uvec, u32 nr_segs) |
bfdc5970 CH |
1148 | { |
1149 | const struct compat_iovec __user *uiov = | |
1150 | (const struct compat_iovec __user *)uvec; | |
bd8c239c KC |
1151 | int ret = -EFAULT; |
1152 | u32 i; | |
bfdc5970 | 1153 | |
a959a978 | 1154 | if (!user_access_begin(uiov, nr_segs * sizeof(*uiov))) |
bfdc5970 CH |
1155 | return -EFAULT; |
1156 | ||
1157 | for (i = 0; i < nr_segs; i++) { | |
1158 | compat_uptr_t buf; | |
1159 | compat_ssize_t len; | |
1160 | ||
1161 | unsafe_get_user(len, &uiov[i].iov_len, uaccess_end); | |
1162 | unsafe_get_user(buf, &uiov[i].iov_base, uaccess_end); | |
1163 | ||
1164 | /* check for compat_size_t not fitting in compat_ssize_t .. */ | |
1165 | if (len < 0) { | |
1166 | ret = -EINVAL; | |
1167 | goto uaccess_end; | |
1168 | } | |
1169 | iov[i].iov_base = compat_ptr(buf); | |
1170 | iov[i].iov_len = len; | |
1171 | } | |
1172 | ||
1173 | ret = 0; | |
1174 | uaccess_end: | |
1175 | user_access_end(); | |
1176 | return ret; | |
1177 | } | |
1178 | ||
719a937b | 1179 | static __noclone int copy_iovec_from_user(struct iovec *iov, |
487c20b0 | 1180 | const struct iovec __user *uiov, unsigned long nr_segs) |
fb041b59 | 1181 | { |
487c20b0 | 1182 | int ret = -EFAULT; |
fb041b59 | 1183 | |
487c20b0 | 1184 | if (!user_access_begin(uiov, nr_segs * sizeof(*uiov))) |
bfdc5970 | 1185 | return -EFAULT; |
fb041b59 | 1186 | |
487c20b0 LT |
1187 | do { |
1188 | void __user *buf; | |
1189 | ssize_t len; | |
1190 | ||
1191 | unsafe_get_user(len, &uiov->iov_len, uaccess_end); | |
1192 | unsafe_get_user(buf, &uiov->iov_base, uaccess_end); | |
1193 | ||
1194 | /* check for size_t not fitting in ssize_t .. */ | |
1195 | if (unlikely(len < 0)) { | |
1196 | ret = -EINVAL; | |
1197 | goto uaccess_end; | |
1198 | } | |
1199 | iov->iov_base = buf; | |
1200 | iov->iov_len = len; | |
1201 | ||
1202 | uiov++; iov++; | |
1203 | } while (--nr_segs); | |
1204 | ||
1205 | ret = 0; | |
1206 | uaccess_end: | |
1207 | user_access_end(); | |
1208 | return ret; | |
bfdc5970 CH |
1209 | } |
1210 | ||
1211 | struct iovec *iovec_from_user(const struct iovec __user *uvec, | |
1212 | unsigned long nr_segs, unsigned long fast_segs, | |
1213 | struct iovec *fast_iov, bool compat) | |
1214 | { | |
1215 | struct iovec *iov = fast_iov; | |
1216 | int ret; | |
1217 | ||
fb041b59 | 1218 | /* |
bfdc5970 CH |
1219 | * SuS says "The readv() function *may* fail if the iovcnt argument was |
1220 | * less than or equal to 0, or greater than {IOV_MAX}. Linux has | |
1221 | * traditionally returned zero for zero segments, so... | |
fb041b59 | 1222 | */ |
bfdc5970 CH |
1223 | if (nr_segs == 0) |
1224 | return iov; | |
1225 | if (nr_segs > UIO_MAXIOV) | |
1226 | return ERR_PTR(-EINVAL); | |
fb041b59 DL |
1227 | if (nr_segs > fast_segs) { |
1228 | iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL); | |
bfdc5970 CH |
1229 | if (!iov) |
1230 | return ERR_PTR(-ENOMEM); | |
fb041b59 | 1231 | } |
bfdc5970 | 1232 | |
487c20b0 | 1233 | if (unlikely(compat)) |
bfdc5970 CH |
1234 | ret = copy_compat_iovec_from_user(iov, uvec, nr_segs); |
1235 | else | |
1236 | ret = copy_iovec_from_user(iov, uvec, nr_segs); | |
1237 | if (ret) { | |
1238 | if (iov != fast_iov) | |
1239 | kfree(iov); | |
1240 | return ERR_PTR(ret); | |
1241 | } | |
1242 | ||
1243 | return iov; | |
1244 | } | |
1245 | ||
3b2deb0e JA |
1246 | /* |
1247 | * Single segment iovec supplied by the user, import it as ITER_UBUF. | |
1248 | */ | |
1249 | static ssize_t __import_iovec_ubuf(int type, const struct iovec __user *uvec, | |
1250 | struct iovec **iovp, struct iov_iter *i, | |
1251 | bool compat) | |
1252 | { | |
1253 | struct iovec *iov = *iovp; | |
1254 | ssize_t ret; | |
1255 | ||
1256 | if (compat) | |
1257 | ret = copy_compat_iovec_from_user(iov, uvec, 1); | |
1258 | else | |
1259 | ret = copy_iovec_from_user(iov, uvec, 1); | |
1260 | if (unlikely(ret)) | |
1261 | return ret; | |
1262 | ||
1263 | ret = import_ubuf(type, iov->iov_base, iov->iov_len, i); | |
1264 | if (unlikely(ret)) | |
1265 | return ret; | |
1266 | *iovp = NULL; | |
1267 | return i->count; | |
1268 | } | |
1269 | ||
bfdc5970 CH |
1270 | ssize_t __import_iovec(int type, const struct iovec __user *uvec, |
1271 | unsigned nr_segs, unsigned fast_segs, struct iovec **iovp, | |
1272 | struct iov_iter *i, bool compat) | |
1273 | { | |
1274 | ssize_t total_len = 0; | |
1275 | unsigned long seg; | |
1276 | struct iovec *iov; | |
1277 | ||
3b2deb0e JA |
1278 | if (nr_segs == 1) |
1279 | return __import_iovec_ubuf(type, uvec, iovp, i, compat); | |
1280 | ||
bfdc5970 CH |
1281 | iov = iovec_from_user(uvec, nr_segs, fast_segs, *iovp, compat); |
1282 | if (IS_ERR(iov)) { | |
1283 | *iovp = NULL; | |
1284 | return PTR_ERR(iov); | |
fb041b59 DL |
1285 | } |
1286 | ||
1287 | /* | |
bfdc5970 CH |
1288 | * According to the Single Unix Specification we should return EINVAL if |
1289 | * an element length is < 0 when cast to ssize_t or if the total length | |
1290 | * would overflow the ssize_t return value of the system call. | |
fb041b59 DL |
1291 | * |
1292 | * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the | |
1293 | * overflow case. | |
1294 | */ | |
fb041b59 | 1295 | for (seg = 0; seg < nr_segs; seg++) { |
fb041b59 DL |
1296 | ssize_t len = (ssize_t)iov[seg].iov_len; |
1297 | ||
bfdc5970 CH |
1298 | if (!access_ok(iov[seg].iov_base, len)) { |
1299 | if (iov != *iovp) | |
1300 | kfree(iov); | |
1301 | *iovp = NULL; | |
1302 | return -EFAULT; | |
fb041b59 | 1303 | } |
bfdc5970 CH |
1304 | |
1305 | if (len > MAX_RW_COUNT - total_len) { | |
1306 | len = MAX_RW_COUNT - total_len; | |
fb041b59 DL |
1307 | iov[seg].iov_len = len; |
1308 | } | |
bfdc5970 | 1309 | total_len += len; |
fb041b59 | 1310 | } |
bfdc5970 CH |
1311 | |
1312 | iov_iter_init(i, type, iov, nr_segs, total_len); | |
1313 | if (iov == *iovp) | |
1314 | *iovp = NULL; | |
1315 | else | |
1316 | *iovp = iov; | |
1317 | return total_len; | |
fb041b59 DL |
1318 | } |
1319 | ||
ffecee4f VN |
1320 | /** |
1321 | * import_iovec() - Copy an array of &struct iovec from userspace | |
1322 | * into the kernel, check that it is valid, and initialize a new | |
1323 | * &struct iov_iter iterator to access it. | |
1324 | * | |
1325 | * @type: One of %READ or %WRITE. | |
bfdc5970 | 1326 | * @uvec: Pointer to the userspace array. |
ffecee4f VN |
1327 | * @nr_segs: Number of elements in userspace array. |
1328 | * @fast_segs: Number of elements in @iov. | |
bfdc5970 | 1329 | * @iovp: (input and output parameter) Pointer to pointer to (usually small |
ffecee4f VN |
1330 | * on-stack) kernel array. |
1331 | * @i: Pointer to iterator that will be initialized on success. | |
1332 | * | |
1333 | * If the array pointed to by *@iov is large enough to hold all @nr_segs, | |
1334 | * then this function places %NULL in *@iov on return. Otherwise, a new | |
1335 | * array will be allocated and the result placed in *@iov. This means that | |
1336 | * the caller may call kfree() on *@iov regardless of whether the small | |
1337 | * on-stack array was used or not (and regardless of whether this function | |
1338 | * returns an error or not). | |
1339 | * | |
87e5e6da | 1340 | * Return: Negative error code on error, bytes imported on success |
ffecee4f | 1341 | */ |
bfdc5970 | 1342 | ssize_t import_iovec(int type, const struct iovec __user *uvec, |
bc917be8 | 1343 | unsigned nr_segs, unsigned fast_segs, |
bfdc5970 | 1344 | struct iovec **iovp, struct iov_iter *i) |
bc917be8 | 1345 | { |
89cd35c5 CH |
1346 | return __import_iovec(type, uvec, nr_segs, fast_segs, iovp, i, |
1347 | in_compat_syscall()); | |
bc917be8 AV |
1348 | } |
1349 | EXPORT_SYMBOL(import_iovec); | |
1350 | ||
2ad9bd83 JA |
1351 | int import_ubuf(int rw, void __user *buf, size_t len, struct iov_iter *i) |
1352 | { | |
1353 | if (len > MAX_RW_COUNT) | |
1354 | len = MAX_RW_COUNT; | |
1355 | if (unlikely(!access_ok(buf, len))) | |
1356 | return -EFAULT; | |
1357 | ||
1358 | iov_iter_ubuf(i, rw, buf, len); | |
1359 | return 0; | |
1360 | } | |
70e969eb | 1361 | EXPORT_SYMBOL_GPL(import_ubuf); |
2ad9bd83 | 1362 | |
8fb0f47a JA |
1363 | /** |
1364 | * iov_iter_restore() - Restore a &struct iov_iter to the same state as when | |
1365 | * iov_iter_save_state() was called. | |
1366 | * | |
1367 | * @i: &struct iov_iter to restore | |
1368 | * @state: state to restore from | |
1369 | * | |
1370 | * Used after iov_iter_save_state() to bring restore @i, if operations may | |
1371 | * have advanced it. | |
1372 | * | |
1373 | * Note: only works on ITER_IOVEC, ITER_BVEC, and ITER_KVEC | |
1374 | */ | |
1375 | void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state) | |
1376 | { | |
4397a17c KB |
1377 | if (WARN_ON_ONCE(!iov_iter_is_bvec(i) && !iter_is_iovec(i) && |
1378 | !iter_is_ubuf(i)) && !iov_iter_is_kvec(i)) | |
8fb0f47a JA |
1379 | return; |
1380 | i->iov_offset = state->iov_offset; | |
1381 | i->count = state->count; | |
fcb14cb1 AV |
1382 | if (iter_is_ubuf(i)) |
1383 | return; | |
8fb0f47a JA |
1384 | /* |
1385 | * For the *vec iters, nr_segs + iov is constant - if we increment | |
1386 | * the vec, then we also decrement the nr_segs count. Hence we don't | |
1387 | * need to track both of these, just one is enough and we can deduct | |
1388 | * the other from that. ITER_KVEC and ITER_IOVEC are the same struct | |
1389 | * size, so we can just increment the iov pointer as they are unionzed. | |
1390 | * ITER_BVEC _may_ be the same size on some archs, but on others it is | |
1391 | * not. Be safe and handle it separately. | |
1392 | */ | |
1393 | BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec)); | |
1394 | if (iov_iter_is_bvec(i)) | |
1395 | i->bvec -= state->nr_segs - i->nr_segs; | |
1396 | else | |
de4f5fed | 1397 | i->__iov -= state->nr_segs - i->nr_segs; |
8fb0f47a JA |
1398 | i->nr_segs = state->nr_segs; |
1399 | } | |
7d58fe73 DH |
1400 | |
1401 | /* | |
1402 | * Extract a list of contiguous pages from an ITER_XARRAY iterator. This does not | |
1403 | * get references on the pages, nor does it get a pin on them. | |
1404 | */ | |
1405 | static ssize_t iov_iter_extract_xarray_pages(struct iov_iter *i, | |
1406 | struct page ***pages, size_t maxsize, | |
1407 | unsigned int maxpages, | |
1408 | iov_iter_extraction_t extraction_flags, | |
1409 | size_t *offset0) | |
1410 | { | |
1411 | struct page *page, **p; | |
1412 | unsigned int nr = 0, offset; | |
1413 | loff_t pos = i->xarray_start + i->iov_offset; | |
1414 | pgoff_t index = pos >> PAGE_SHIFT; | |
1415 | XA_STATE(xas, i->xarray, index); | |
1416 | ||
1417 | offset = pos & ~PAGE_MASK; | |
1418 | *offset0 = offset; | |
1419 | ||
1420 | maxpages = want_pages_array(pages, maxsize, offset, maxpages); | |
1421 | if (!maxpages) | |
1422 | return -ENOMEM; | |
1423 | p = *pages; | |
1424 | ||
1425 | rcu_read_lock(); | |
1426 | for (page = xas_load(&xas); page; page = xas_next(&xas)) { | |
1427 | if (xas_retry(&xas, page)) | |
1428 | continue; | |
1429 | ||
1430 | /* Has the page moved or been split? */ | |
1431 | if (unlikely(page != xas_reload(&xas))) { | |
1432 | xas_reset(&xas); | |
1433 | continue; | |
1434 | } | |
1435 | ||
1436 | p[nr++] = find_subpage(page, xas.xa_index); | |
1437 | if (nr == maxpages) | |
1438 | break; | |
1439 | } | |
1440 | rcu_read_unlock(); | |
1441 | ||
1442 | maxsize = min_t(size_t, nr * PAGE_SIZE - offset, maxsize); | |
1443 | iov_iter_advance(i, maxsize); | |
1444 | return maxsize; | |
1445 | } | |
1446 | ||
1447 | /* | |
1448 | * Extract a list of contiguous pages from an ITER_BVEC iterator. This does | |
1449 | * not get references on the pages, nor does it get a pin on them. | |
1450 | */ | |
1451 | static ssize_t iov_iter_extract_bvec_pages(struct iov_iter *i, | |
1452 | struct page ***pages, size_t maxsize, | |
1453 | unsigned int maxpages, | |
1454 | iov_iter_extraction_t extraction_flags, | |
1455 | size_t *offset0) | |
1456 | { | |
1457 | struct page **p, *page; | |
f741bd71 | 1458 | size_t skip = i->iov_offset, offset, size; |
7d58fe73 DH |
1459 | int k; |
1460 | ||
1461 | for (;;) { | |
1462 | if (i->nr_segs == 0) | |
1463 | return 0; | |
f741bd71 DH |
1464 | size = min(maxsize, i->bvec->bv_len - skip); |
1465 | if (size) | |
7d58fe73 DH |
1466 | break; |
1467 | i->iov_offset = 0; | |
1468 | i->nr_segs--; | |
1469 | i->bvec++; | |
1470 | skip = 0; | |
1471 | } | |
1472 | ||
1473 | skip += i->bvec->bv_offset; | |
1474 | page = i->bvec->bv_page + skip / PAGE_SIZE; | |
1475 | offset = skip % PAGE_SIZE; | |
1476 | *offset0 = offset; | |
1477 | ||
f741bd71 | 1478 | maxpages = want_pages_array(pages, size, offset, maxpages); |
7d58fe73 DH |
1479 | if (!maxpages) |
1480 | return -ENOMEM; | |
1481 | p = *pages; | |
1482 | for (k = 0; k < maxpages; k++) | |
1483 | p[k] = page + k; | |
1484 | ||
f741bd71 DH |
1485 | size = min_t(size_t, size, maxpages * PAGE_SIZE - offset); |
1486 | iov_iter_advance(i, size); | |
1487 | return size; | |
7d58fe73 DH |
1488 | } |
1489 | ||
1490 | /* | |
1491 | * Extract a list of virtually contiguous pages from an ITER_KVEC iterator. | |
1492 | * This does not get references on the pages, nor does it get a pin on them. | |
1493 | */ | |
1494 | static ssize_t iov_iter_extract_kvec_pages(struct iov_iter *i, | |
1495 | struct page ***pages, size_t maxsize, | |
1496 | unsigned int maxpages, | |
1497 | iov_iter_extraction_t extraction_flags, | |
1498 | size_t *offset0) | |
1499 | { | |
1500 | struct page **p, *page; | |
1501 | const void *kaddr; | |
f741bd71 | 1502 | size_t skip = i->iov_offset, offset, len, size; |
7d58fe73 DH |
1503 | int k; |
1504 | ||
1505 | for (;;) { | |
1506 | if (i->nr_segs == 0) | |
1507 | return 0; | |
f741bd71 DH |
1508 | size = min(maxsize, i->kvec->iov_len - skip); |
1509 | if (size) | |
7d58fe73 DH |
1510 | break; |
1511 | i->iov_offset = 0; | |
1512 | i->nr_segs--; | |
1513 | i->kvec++; | |
1514 | skip = 0; | |
1515 | } | |
1516 | ||
1517 | kaddr = i->kvec->iov_base + skip; | |
1518 | offset = (unsigned long)kaddr & ~PAGE_MASK; | |
1519 | *offset0 = offset; | |
1520 | ||
f741bd71 | 1521 | maxpages = want_pages_array(pages, size, offset, maxpages); |
7d58fe73 DH |
1522 | if (!maxpages) |
1523 | return -ENOMEM; | |
1524 | p = *pages; | |
1525 | ||
1526 | kaddr -= offset; | |
f741bd71 | 1527 | len = offset + size; |
7d58fe73 DH |
1528 | for (k = 0; k < maxpages; k++) { |
1529 | size_t seg = min_t(size_t, len, PAGE_SIZE); | |
1530 | ||
1531 | if (is_vmalloc_or_module_addr(kaddr)) | |
1532 | page = vmalloc_to_page(kaddr); | |
1533 | else | |
1534 | page = virt_to_page(kaddr); | |
1535 | ||
1536 | p[k] = page; | |
1537 | len -= seg; | |
1538 | kaddr += PAGE_SIZE; | |
1539 | } | |
1540 | ||
f741bd71 DH |
1541 | size = min_t(size_t, size, maxpages * PAGE_SIZE - offset); |
1542 | iov_iter_advance(i, size); | |
1543 | return size; | |
7d58fe73 DH |
1544 | } |
1545 | ||
1546 | /* | |
1547 | * Extract a list of contiguous pages from a user iterator and get a pin on | |
1548 | * each of them. This should only be used if the iterator is user-backed | |
1549 | * (IOBUF/UBUF). | |
1550 | * | |
1551 | * It does not get refs on the pages, but the pages must be unpinned by the | |
1552 | * caller once the transfer is complete. | |
1553 | * | |
1554 | * This is safe to be used where background IO/DMA *is* going to be modifying | |
1555 | * the buffer; using a pin rather than a ref makes forces fork() to give the | |
1556 | * child a copy of the page. | |
1557 | */ | |
1558 | static ssize_t iov_iter_extract_user_pages(struct iov_iter *i, | |
1559 | struct page ***pages, | |
1560 | size_t maxsize, | |
1561 | unsigned int maxpages, | |
1562 | iov_iter_extraction_t extraction_flags, | |
1563 | size_t *offset0) | |
1564 | { | |
1565 | unsigned long addr; | |
1566 | unsigned int gup_flags = 0; | |
1567 | size_t offset; | |
1568 | int res; | |
1569 | ||
1570 | if (i->data_source == ITER_DEST) | |
1571 | gup_flags |= FOLL_WRITE; | |
1572 | if (extraction_flags & ITER_ALLOW_P2PDMA) | |
1573 | gup_flags |= FOLL_PCI_P2PDMA; | |
1574 | if (i->nofault) | |
1575 | gup_flags |= FOLL_NOFAULT; | |
1576 | ||
1577 | addr = first_iovec_segment(i, &maxsize); | |
1578 | *offset0 = offset = addr % PAGE_SIZE; | |
1579 | addr &= PAGE_MASK; | |
1580 | maxpages = want_pages_array(pages, maxsize, offset, maxpages); | |
1581 | if (!maxpages) | |
1582 | return -ENOMEM; | |
1583 | res = pin_user_pages_fast(addr, maxpages, gup_flags, *pages); | |
1584 | if (unlikely(res <= 0)) | |
1585 | return res; | |
1586 | maxsize = min_t(size_t, maxsize, res * PAGE_SIZE - offset); | |
1587 | iov_iter_advance(i, maxsize); | |
1588 | return maxsize; | |
1589 | } | |
1590 | ||
1591 | /** | |
1592 | * iov_iter_extract_pages - Extract a list of contiguous pages from an iterator | |
1593 | * @i: The iterator to extract from | |
1594 | * @pages: Where to return the list of pages | |
1595 | * @maxsize: The maximum amount of iterator to extract | |
1596 | * @maxpages: The maximum size of the list of pages | |
1597 | * @extraction_flags: Flags to qualify request | |
1598 | * @offset0: Where to return the starting offset into (*@pages)[0] | |
1599 | * | |
1600 | * Extract a list of contiguous pages from the current point of the iterator, | |
1601 | * advancing the iterator. The maximum number of pages and the maximum amount | |
1602 | * of page contents can be set. | |
1603 | * | |
1604 | * If *@pages is NULL, a page list will be allocated to the required size and | |
1605 | * *@pages will be set to its base. If *@pages is not NULL, it will be assumed | |
1606 | * that the caller allocated a page list at least @maxpages in size and this | |
1607 | * will be filled in. | |
1608 | * | |
1609 | * @extraction_flags can have ITER_ALLOW_P2PDMA set to request peer-to-peer DMA | |
1610 | * be allowed on the pages extracted. | |
1611 | * | |
1612 | * The iov_iter_extract_will_pin() function can be used to query how cleanup | |
1613 | * should be performed. | |
1614 | * | |
1615 | * Extra refs or pins on the pages may be obtained as follows: | |
1616 | * | |
1617 | * (*) If the iterator is user-backed (ITER_IOVEC/ITER_UBUF), pins will be | |
1618 | * added to the pages, but refs will not be taken. | |
1619 | * iov_iter_extract_will_pin() will return true. | |
1620 | * | |
1621 | * (*) If the iterator is ITER_KVEC, ITER_BVEC or ITER_XARRAY, the pages are | |
1622 | * merely listed; no extra refs or pins are obtained. | |
1623 | * iov_iter_extract_will_pin() will return 0. | |
1624 | * | |
1625 | * Note also: | |
1626 | * | |
1627 | * (*) Use with ITER_DISCARD is not supported as that has no content. | |
1628 | * | |
1629 | * On success, the function sets *@pages to the new pagelist, if allocated, and | |
1630 | * sets *offset0 to the offset into the first page. | |
1631 | * | |
1632 | * It may also return -ENOMEM and -EFAULT. | |
1633 | */ | |
1634 | ssize_t iov_iter_extract_pages(struct iov_iter *i, | |
1635 | struct page ***pages, | |
1636 | size_t maxsize, | |
1637 | unsigned int maxpages, | |
1638 | iov_iter_extraction_t extraction_flags, | |
1639 | size_t *offset0) | |
1640 | { | |
1641 | maxsize = min_t(size_t, min_t(size_t, maxsize, i->count), MAX_RW_COUNT); | |
1642 | if (!maxsize) | |
1643 | return 0; | |
1644 | ||
1645 | if (likely(user_backed_iter(i))) | |
1646 | return iov_iter_extract_user_pages(i, pages, maxsize, | |
1647 | maxpages, extraction_flags, | |
1648 | offset0); | |
1649 | if (iov_iter_is_kvec(i)) | |
1650 | return iov_iter_extract_kvec_pages(i, pages, maxsize, | |
1651 | maxpages, extraction_flags, | |
1652 | offset0); | |
1653 | if (iov_iter_is_bvec(i)) | |
1654 | return iov_iter_extract_bvec_pages(i, pages, maxsize, | |
1655 | maxpages, extraction_flags, | |
1656 | offset0); | |
1657 | if (iov_iter_is_xarray(i)) | |
1658 | return iov_iter_extract_xarray_pages(i, pages, maxsize, | |
1659 | maxpages, extraction_flags, | |
1660 | offset0); | |
1661 | return -EFAULT; | |
1662 | } | |
1663 | EXPORT_SYMBOL_GPL(iov_iter_extract_pages); |