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Merge tag 'io_uring-5.13-2021-06-12' of git://git.kernel.dk/linux-block
[mirror_ubuntu-jammy-kernel.git] / lib / iov_iter.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <crypto/hash.h>
3 #include <linux/export.h>
4 #include <linux/bvec.h>
5 #include <linux/fault-inject-usercopy.h>
6 #include <linux/uio.h>
7 #include <linux/pagemap.h>
8 #include <linux/highmem.h>
9 #include <linux/slab.h>
10 #include <linux/vmalloc.h>
11 #include <linux/splice.h>
12 #include <linux/compat.h>
13 #include <net/checksum.h>
14 #include <linux/scatterlist.h>
15 #include <linux/instrumented.h>
16
17 #define PIPE_PARANOIA /* for now */
18
19 #define iterate_iovec(i, n, __v, __p, skip, STEP) { \
20 size_t left; \
21 size_t wanted = n; \
22 __p = i->iov; \
23 __v.iov_len = min(n, __p->iov_len - skip); \
24 if (likely(__v.iov_len)) { \
25 __v.iov_base = __p->iov_base + skip; \
26 left = (STEP); \
27 __v.iov_len -= left; \
28 skip += __v.iov_len; \
29 n -= __v.iov_len; \
30 } else { \
31 left = 0; \
32 } \
33 while (unlikely(!left && n)) { \
34 __p++; \
35 __v.iov_len = min(n, __p->iov_len); \
36 if (unlikely(!__v.iov_len)) \
37 continue; \
38 __v.iov_base = __p->iov_base; \
39 left = (STEP); \
40 __v.iov_len -= left; \
41 skip = __v.iov_len; \
42 n -= __v.iov_len; \
43 } \
44 n = wanted - n; \
45 }
46
47 #define iterate_kvec(i, n, __v, __p, skip, STEP) { \
48 size_t wanted = n; \
49 __p = i->kvec; \
50 __v.iov_len = min(n, __p->iov_len - skip); \
51 if (likely(__v.iov_len)) { \
52 __v.iov_base = __p->iov_base + skip; \
53 (void)(STEP); \
54 skip += __v.iov_len; \
55 n -= __v.iov_len; \
56 } \
57 while (unlikely(n)) { \
58 __p++; \
59 __v.iov_len = min(n, __p->iov_len); \
60 if (unlikely(!__v.iov_len)) \
61 continue; \
62 __v.iov_base = __p->iov_base; \
63 (void)(STEP); \
64 skip = __v.iov_len; \
65 n -= __v.iov_len; \
66 } \
67 n = wanted; \
68 }
69
70 #define iterate_bvec(i, n, __v, __bi, skip, STEP) { \
71 struct bvec_iter __start; \
72 __start.bi_size = n; \
73 __start.bi_bvec_done = skip; \
74 __start.bi_idx = 0; \
75 for_each_bvec(__v, i->bvec, __bi, __start) { \
76 (void)(STEP); \
77 } \
78 }
79
80 #define iterate_xarray(i, n, __v, skip, STEP) { \
81 struct page *head = NULL; \
82 size_t wanted = n, seg, offset; \
83 loff_t start = i->xarray_start + skip; \
84 pgoff_t index = start >> PAGE_SHIFT; \
85 int j; \
86 \
87 XA_STATE(xas, i->xarray, index); \
88 \
89 rcu_read_lock(); \
90 xas_for_each(&xas, head, ULONG_MAX) { \
91 if (xas_retry(&xas, head)) \
92 continue; \
93 if (WARN_ON(xa_is_value(head))) \
94 break; \
95 if (WARN_ON(PageHuge(head))) \
96 break; \
97 for (j = (head->index < index) ? index - head->index : 0; \
98 j < thp_nr_pages(head); j++) { \
99 __v.bv_page = head + j; \
100 offset = (i->xarray_start + skip) & ~PAGE_MASK; \
101 seg = PAGE_SIZE - offset; \
102 __v.bv_offset = offset; \
103 __v.bv_len = min(n, seg); \
104 (void)(STEP); \
105 n -= __v.bv_len; \
106 skip += __v.bv_len; \
107 if (n == 0) \
108 break; \
109 } \
110 if (n == 0) \
111 break; \
112 } \
113 rcu_read_unlock(); \
114 n = wanted - n; \
115 }
116
117 #define iterate_all_kinds(i, n, v, I, B, K, X) { \
118 if (likely(n)) { \
119 size_t skip = i->iov_offset; \
120 if (unlikely(i->type & ITER_BVEC)) { \
121 struct bio_vec v; \
122 struct bvec_iter __bi; \
123 iterate_bvec(i, n, v, __bi, skip, (B)) \
124 } else if (unlikely(i->type & ITER_KVEC)) { \
125 const struct kvec *kvec; \
126 struct kvec v; \
127 iterate_kvec(i, n, v, kvec, skip, (K)) \
128 } else if (unlikely(i->type & ITER_DISCARD)) { \
129 } else if (unlikely(i->type & ITER_XARRAY)) { \
130 struct bio_vec v; \
131 iterate_xarray(i, n, v, skip, (X)); \
132 } else { \
133 const struct iovec *iov; \
134 struct iovec v; \
135 iterate_iovec(i, n, v, iov, skip, (I)) \
136 } \
137 } \
138 }
139
140 #define iterate_and_advance(i, n, v, I, B, K, X) { \
141 if (unlikely(i->count < n)) \
142 n = i->count; \
143 if (i->count) { \
144 size_t skip = i->iov_offset; \
145 if (unlikely(i->type & ITER_BVEC)) { \
146 const struct bio_vec *bvec = i->bvec; \
147 struct bio_vec v; \
148 struct bvec_iter __bi; \
149 iterate_bvec(i, n, v, __bi, skip, (B)) \
150 i->bvec = __bvec_iter_bvec(i->bvec, __bi); \
151 i->nr_segs -= i->bvec - bvec; \
152 skip = __bi.bi_bvec_done; \
153 } else if (unlikely(i->type & ITER_KVEC)) { \
154 const struct kvec *kvec; \
155 struct kvec v; \
156 iterate_kvec(i, n, v, kvec, skip, (K)) \
157 if (skip == kvec->iov_len) { \
158 kvec++; \
159 skip = 0; \
160 } \
161 i->nr_segs -= kvec - i->kvec; \
162 i->kvec = kvec; \
163 } else if (unlikely(i->type & ITER_DISCARD)) { \
164 skip += n; \
165 } else if (unlikely(i->type & ITER_XARRAY)) { \
166 struct bio_vec v; \
167 iterate_xarray(i, n, v, skip, (X)) \
168 } else { \
169 const struct iovec *iov; \
170 struct iovec v; \
171 iterate_iovec(i, n, v, iov, skip, (I)) \
172 if (skip == iov->iov_len) { \
173 iov++; \
174 skip = 0; \
175 } \
176 i->nr_segs -= iov - i->iov; \
177 i->iov = iov; \
178 } \
179 i->count -= n; \
180 i->iov_offset = skip; \
181 } \
182 }
183
184 static int copyout(void __user *to, const void *from, size_t n)
185 {
186 if (should_fail_usercopy())
187 return n;
188 if (access_ok(to, n)) {
189 instrument_copy_to_user(to, from, n);
190 n = raw_copy_to_user(to, from, n);
191 }
192 return n;
193 }
194
195 static int copyin(void *to, const void __user *from, size_t n)
196 {
197 if (should_fail_usercopy())
198 return n;
199 if (access_ok(from, n)) {
200 instrument_copy_from_user(to, from, n);
201 n = raw_copy_from_user(to, from, n);
202 }
203 return n;
204 }
205
206 static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes,
207 struct iov_iter *i)
208 {
209 size_t skip, copy, left, wanted;
210 const struct iovec *iov;
211 char __user *buf;
212 void *kaddr, *from;
213
214 if (unlikely(bytes > i->count))
215 bytes = i->count;
216
217 if (unlikely(!bytes))
218 return 0;
219
220 might_fault();
221 wanted = bytes;
222 iov = i->iov;
223 skip = i->iov_offset;
224 buf = iov->iov_base + skip;
225 copy = min(bytes, iov->iov_len - skip);
226
227 if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_writeable(buf, copy)) {
228 kaddr = kmap_atomic(page);
229 from = kaddr + offset;
230
231 /* first chunk, usually the only one */
232 left = copyout(buf, from, copy);
233 copy -= left;
234 skip += copy;
235 from += copy;
236 bytes -= copy;
237
238 while (unlikely(!left && bytes)) {
239 iov++;
240 buf = iov->iov_base;
241 copy = min(bytes, iov->iov_len);
242 left = copyout(buf, from, copy);
243 copy -= left;
244 skip = copy;
245 from += copy;
246 bytes -= copy;
247 }
248 if (likely(!bytes)) {
249 kunmap_atomic(kaddr);
250 goto done;
251 }
252 offset = from - kaddr;
253 buf += copy;
254 kunmap_atomic(kaddr);
255 copy = min(bytes, iov->iov_len - skip);
256 }
257 /* Too bad - revert to non-atomic kmap */
258
259 kaddr = kmap(page);
260 from = kaddr + offset;
261 left = copyout(buf, from, copy);
262 copy -= left;
263 skip += copy;
264 from += copy;
265 bytes -= copy;
266 while (unlikely(!left && bytes)) {
267 iov++;
268 buf = iov->iov_base;
269 copy = min(bytes, iov->iov_len);
270 left = copyout(buf, from, copy);
271 copy -= left;
272 skip = copy;
273 from += copy;
274 bytes -= copy;
275 }
276 kunmap(page);
277
278 done:
279 if (skip == iov->iov_len) {
280 iov++;
281 skip = 0;
282 }
283 i->count -= wanted - bytes;
284 i->nr_segs -= iov - i->iov;
285 i->iov = iov;
286 i->iov_offset = skip;
287 return wanted - bytes;
288 }
289
290 static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t bytes,
291 struct iov_iter *i)
292 {
293 size_t skip, copy, left, wanted;
294 const struct iovec *iov;
295 char __user *buf;
296 void *kaddr, *to;
297
298 if (unlikely(bytes > i->count))
299 bytes = i->count;
300
301 if (unlikely(!bytes))
302 return 0;
303
304 might_fault();
305 wanted = bytes;
306 iov = i->iov;
307 skip = i->iov_offset;
308 buf = iov->iov_base + skip;
309 copy = min(bytes, iov->iov_len - skip);
310
311 if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_readable(buf, copy)) {
312 kaddr = kmap_atomic(page);
313 to = kaddr + offset;
314
315 /* first chunk, usually the only one */
316 left = copyin(to, buf, copy);
317 copy -= left;
318 skip += copy;
319 to += copy;
320 bytes -= copy;
321
322 while (unlikely(!left && bytes)) {
323 iov++;
324 buf = iov->iov_base;
325 copy = min(bytes, iov->iov_len);
326 left = copyin(to, buf, copy);
327 copy -= left;
328 skip = copy;
329 to += copy;
330 bytes -= copy;
331 }
332 if (likely(!bytes)) {
333 kunmap_atomic(kaddr);
334 goto done;
335 }
336 offset = to - kaddr;
337 buf += copy;
338 kunmap_atomic(kaddr);
339 copy = min(bytes, iov->iov_len - skip);
340 }
341 /* Too bad - revert to non-atomic kmap */
342
343 kaddr = kmap(page);
344 to = kaddr + offset;
345 left = copyin(to, buf, copy);
346 copy -= left;
347 skip += copy;
348 to += copy;
349 bytes -= copy;
350 while (unlikely(!left && bytes)) {
351 iov++;
352 buf = iov->iov_base;
353 copy = min(bytes, iov->iov_len);
354 left = copyin(to, buf, copy);
355 copy -= left;
356 skip = copy;
357 to += copy;
358 bytes -= copy;
359 }
360 kunmap(page);
361
362 done:
363 if (skip == iov->iov_len) {
364 iov++;
365 skip = 0;
366 }
367 i->count -= wanted - bytes;
368 i->nr_segs -= iov - i->iov;
369 i->iov = iov;
370 i->iov_offset = skip;
371 return wanted - bytes;
372 }
373
374 #ifdef PIPE_PARANOIA
375 static bool sanity(const struct iov_iter *i)
376 {
377 struct pipe_inode_info *pipe = i->pipe;
378 unsigned int p_head = pipe->head;
379 unsigned int p_tail = pipe->tail;
380 unsigned int p_mask = pipe->ring_size - 1;
381 unsigned int p_occupancy = pipe_occupancy(p_head, p_tail);
382 unsigned int i_head = i->head;
383 unsigned int idx;
384
385 if (i->iov_offset) {
386 struct pipe_buffer *p;
387 if (unlikely(p_occupancy == 0))
388 goto Bad; // pipe must be non-empty
389 if (unlikely(i_head != p_head - 1))
390 goto Bad; // must be at the last buffer...
391
392 p = &pipe->bufs[i_head & p_mask];
393 if (unlikely(p->offset + p->len != i->iov_offset))
394 goto Bad; // ... at the end of segment
395 } else {
396 if (i_head != p_head)
397 goto Bad; // must be right after the last buffer
398 }
399 return true;
400 Bad:
401 printk(KERN_ERR "idx = %d, offset = %zd\n", i_head, i->iov_offset);
402 printk(KERN_ERR "head = %d, tail = %d, buffers = %d\n",
403 p_head, p_tail, pipe->ring_size);
404 for (idx = 0; idx < pipe->ring_size; idx++)
405 printk(KERN_ERR "[%p %p %d %d]\n",
406 pipe->bufs[idx].ops,
407 pipe->bufs[idx].page,
408 pipe->bufs[idx].offset,
409 pipe->bufs[idx].len);
410 WARN_ON(1);
411 return false;
412 }
413 #else
414 #define sanity(i) true
415 #endif
416
417 static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes,
418 struct iov_iter *i)
419 {
420 struct pipe_inode_info *pipe = i->pipe;
421 struct pipe_buffer *buf;
422 unsigned int p_tail = pipe->tail;
423 unsigned int p_mask = pipe->ring_size - 1;
424 unsigned int i_head = i->head;
425 size_t off;
426
427 if (unlikely(bytes > i->count))
428 bytes = i->count;
429
430 if (unlikely(!bytes))
431 return 0;
432
433 if (!sanity(i))
434 return 0;
435
436 off = i->iov_offset;
437 buf = &pipe->bufs[i_head & p_mask];
438 if (off) {
439 if (offset == off && buf->page == page) {
440 /* merge with the last one */
441 buf->len += bytes;
442 i->iov_offset += bytes;
443 goto out;
444 }
445 i_head++;
446 buf = &pipe->bufs[i_head & p_mask];
447 }
448 if (pipe_full(i_head, p_tail, pipe->max_usage))
449 return 0;
450
451 buf->ops = &page_cache_pipe_buf_ops;
452 get_page(page);
453 buf->page = page;
454 buf->offset = offset;
455 buf->len = bytes;
456
457 pipe->head = i_head + 1;
458 i->iov_offset = offset + bytes;
459 i->head = i_head;
460 out:
461 i->count -= bytes;
462 return bytes;
463 }
464
465 /*
466 * Fault in one or more iovecs of the given iov_iter, to a maximum length of
467 * bytes. For each iovec, fault in each page that constitutes the iovec.
468 *
469 * Return 0 on success, or non-zero if the memory could not be accessed (i.e.
470 * because it is an invalid address).
471 */
472 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
473 {
474 size_t skip = i->iov_offset;
475 const struct iovec *iov;
476 int err;
477 struct iovec v;
478
479 if (!(i->type & (ITER_BVEC|ITER_KVEC))) {
480 iterate_iovec(i, bytes, v, iov, skip, ({
481 err = fault_in_pages_readable(v.iov_base, v.iov_len);
482 if (unlikely(err))
483 return err;
484 0;}))
485 }
486 return 0;
487 }
488 EXPORT_SYMBOL(iov_iter_fault_in_readable);
489
490 void iov_iter_init(struct iov_iter *i, unsigned int direction,
491 const struct iovec *iov, unsigned long nr_segs,
492 size_t count)
493 {
494 WARN_ON(direction & ~(READ | WRITE));
495 direction &= READ | WRITE;
496
497 /* It will get better. Eventually... */
498 if (uaccess_kernel()) {
499 i->type = ITER_KVEC | direction;
500 i->kvec = (struct kvec *)iov;
501 } else {
502 i->type = ITER_IOVEC | direction;
503 i->iov = iov;
504 }
505 i->nr_segs = nr_segs;
506 i->iov_offset = 0;
507 i->count = count;
508 }
509 EXPORT_SYMBOL(iov_iter_init);
510
511 static inline bool allocated(struct pipe_buffer *buf)
512 {
513 return buf->ops == &default_pipe_buf_ops;
514 }
515
516 static inline void data_start(const struct iov_iter *i,
517 unsigned int *iter_headp, size_t *offp)
518 {
519 unsigned int p_mask = i->pipe->ring_size - 1;
520 unsigned int iter_head = i->head;
521 size_t off = i->iov_offset;
522
523 if (off && (!allocated(&i->pipe->bufs[iter_head & p_mask]) ||
524 off == PAGE_SIZE)) {
525 iter_head++;
526 off = 0;
527 }
528 *iter_headp = iter_head;
529 *offp = off;
530 }
531
532 static size_t push_pipe(struct iov_iter *i, size_t size,
533 int *iter_headp, size_t *offp)
534 {
535 struct pipe_inode_info *pipe = i->pipe;
536 unsigned int p_tail = pipe->tail;
537 unsigned int p_mask = pipe->ring_size - 1;
538 unsigned int iter_head;
539 size_t off;
540 ssize_t left;
541
542 if (unlikely(size > i->count))
543 size = i->count;
544 if (unlikely(!size))
545 return 0;
546
547 left = size;
548 data_start(i, &iter_head, &off);
549 *iter_headp = iter_head;
550 *offp = off;
551 if (off) {
552 left -= PAGE_SIZE - off;
553 if (left <= 0) {
554 pipe->bufs[iter_head & p_mask].len += size;
555 return size;
556 }
557 pipe->bufs[iter_head & p_mask].len = PAGE_SIZE;
558 iter_head++;
559 }
560 while (!pipe_full(iter_head, p_tail, pipe->max_usage)) {
561 struct pipe_buffer *buf = &pipe->bufs[iter_head & p_mask];
562 struct page *page = alloc_page(GFP_USER);
563 if (!page)
564 break;
565
566 buf->ops = &default_pipe_buf_ops;
567 buf->page = page;
568 buf->offset = 0;
569 buf->len = min_t(ssize_t, left, PAGE_SIZE);
570 left -= buf->len;
571 iter_head++;
572 pipe->head = iter_head;
573
574 if (left == 0)
575 return size;
576 }
577 return size - left;
578 }
579
580 static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
581 struct iov_iter *i)
582 {
583 struct pipe_inode_info *pipe = i->pipe;
584 unsigned int p_mask = pipe->ring_size - 1;
585 unsigned int i_head;
586 size_t n, off;
587
588 if (!sanity(i))
589 return 0;
590
591 bytes = n = push_pipe(i, bytes, &i_head, &off);
592 if (unlikely(!n))
593 return 0;
594 do {
595 size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
596 memcpy_to_page(pipe->bufs[i_head & p_mask].page, off, addr, chunk);
597 i->head = i_head;
598 i->iov_offset = off + chunk;
599 n -= chunk;
600 addr += chunk;
601 off = 0;
602 i_head++;
603 } while (n);
604 i->count -= bytes;
605 return bytes;
606 }
607
608 static __wsum csum_and_memcpy(void *to, const void *from, size_t len,
609 __wsum sum, size_t off)
610 {
611 __wsum next = csum_partial_copy_nocheck(from, to, len);
612 return csum_block_add(sum, next, off);
613 }
614
615 static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes,
616 struct csum_state *csstate,
617 struct iov_iter *i)
618 {
619 struct pipe_inode_info *pipe = i->pipe;
620 unsigned int p_mask = pipe->ring_size - 1;
621 __wsum sum = csstate->csum;
622 size_t off = csstate->off;
623 unsigned int i_head;
624 size_t n, r;
625
626 if (!sanity(i))
627 return 0;
628
629 bytes = n = push_pipe(i, bytes, &i_head, &r);
630 if (unlikely(!n))
631 return 0;
632 do {
633 size_t chunk = min_t(size_t, n, PAGE_SIZE - r);
634 char *p = kmap_atomic(pipe->bufs[i_head & p_mask].page);
635 sum = csum_and_memcpy(p + r, addr, chunk, sum, off);
636 kunmap_atomic(p);
637 i->head = i_head;
638 i->iov_offset = r + chunk;
639 n -= chunk;
640 off += chunk;
641 addr += chunk;
642 r = 0;
643 i_head++;
644 } while (n);
645 i->count -= bytes;
646 csstate->csum = sum;
647 csstate->off = off;
648 return bytes;
649 }
650
651 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
652 {
653 const char *from = addr;
654 if (unlikely(iov_iter_is_pipe(i)))
655 return copy_pipe_to_iter(addr, bytes, i);
656 if (iter_is_iovec(i))
657 might_fault();
658 iterate_and_advance(i, bytes, v,
659 copyout(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len),
660 memcpy_to_page(v.bv_page, v.bv_offset,
661 (from += v.bv_len) - v.bv_len, v.bv_len),
662 memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len),
663 memcpy_to_page(v.bv_page, v.bv_offset,
664 (from += v.bv_len) - v.bv_len, v.bv_len)
665 )
666
667 return bytes;
668 }
669 EXPORT_SYMBOL(_copy_to_iter);
670
671 #ifdef CONFIG_ARCH_HAS_COPY_MC
672 static int copyout_mc(void __user *to, const void *from, size_t n)
673 {
674 if (access_ok(to, n)) {
675 instrument_copy_to_user(to, from, n);
676 n = copy_mc_to_user((__force void *) to, from, n);
677 }
678 return n;
679 }
680
681 static unsigned long copy_mc_to_page(struct page *page, size_t offset,
682 const char *from, size_t len)
683 {
684 unsigned long ret;
685 char *to;
686
687 to = kmap_atomic(page);
688 ret = copy_mc_to_kernel(to + offset, from, len);
689 kunmap_atomic(to);
690
691 return ret;
692 }
693
694 static size_t copy_mc_pipe_to_iter(const void *addr, size_t bytes,
695 struct iov_iter *i)
696 {
697 struct pipe_inode_info *pipe = i->pipe;
698 unsigned int p_mask = pipe->ring_size - 1;
699 unsigned int i_head;
700 size_t n, off, xfer = 0;
701
702 if (!sanity(i))
703 return 0;
704
705 bytes = n = push_pipe(i, bytes, &i_head, &off);
706 if (unlikely(!n))
707 return 0;
708 do {
709 size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
710 unsigned long rem;
711
712 rem = copy_mc_to_page(pipe->bufs[i_head & p_mask].page,
713 off, addr, chunk);
714 i->head = i_head;
715 i->iov_offset = off + chunk - rem;
716 xfer += chunk - rem;
717 if (rem)
718 break;
719 n -= chunk;
720 addr += chunk;
721 off = 0;
722 i_head++;
723 } while (n);
724 i->count -= xfer;
725 return xfer;
726 }
727
728 /**
729 * _copy_mc_to_iter - copy to iter with source memory error exception handling
730 * @addr: source kernel address
731 * @bytes: total transfer length
732 * @iter: destination iterator
733 *
734 * The pmem driver deploys this for the dax operation
735 * (dax_copy_to_iter()) for dax reads (bypass page-cache and the
736 * block-layer). Upon #MC read(2) aborts and returns EIO or the bytes
737 * successfully copied.
738 *
739 * The main differences between this and typical _copy_to_iter().
740 *
741 * * Typical tail/residue handling after a fault retries the copy
742 * byte-by-byte until the fault happens again. Re-triggering machine
743 * checks is potentially fatal so the implementation uses source
744 * alignment and poison alignment assumptions to avoid re-triggering
745 * hardware exceptions.
746 *
747 * * ITER_KVEC, ITER_PIPE, and ITER_BVEC can return short copies.
748 * Compare to copy_to_iter() where only ITER_IOVEC attempts might return
749 * a short copy.
750 */
751 size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
752 {
753 const char *from = addr;
754 unsigned long rem, curr_addr, s_addr = (unsigned long) addr;
755
756 if (unlikely(iov_iter_is_pipe(i)))
757 return copy_mc_pipe_to_iter(addr, bytes, i);
758 if (iter_is_iovec(i))
759 might_fault();
760 iterate_and_advance(i, bytes, v,
761 copyout_mc(v.iov_base, (from += v.iov_len) - v.iov_len,
762 v.iov_len),
763 ({
764 rem = copy_mc_to_page(v.bv_page, v.bv_offset,
765 (from += v.bv_len) - v.bv_len, v.bv_len);
766 if (rem) {
767 curr_addr = (unsigned long) from;
768 bytes = curr_addr - s_addr - rem;
769 return bytes;
770 }
771 }),
772 ({
773 rem = copy_mc_to_kernel(v.iov_base, (from += v.iov_len)
774 - v.iov_len, v.iov_len);
775 if (rem) {
776 curr_addr = (unsigned long) from;
777 bytes = curr_addr - s_addr - rem;
778 return bytes;
779 }
780 }),
781 ({
782 rem = copy_mc_to_page(v.bv_page, v.bv_offset,
783 (from += v.bv_len) - v.bv_len, v.bv_len);
784 if (rem) {
785 curr_addr = (unsigned long) from;
786 bytes = curr_addr - s_addr - rem;
787 rcu_read_unlock();
788 i->iov_offset += bytes;
789 i->count -= bytes;
790 return bytes;
791 }
792 })
793 )
794
795 return bytes;
796 }
797 EXPORT_SYMBOL_GPL(_copy_mc_to_iter);
798 #endif /* CONFIG_ARCH_HAS_COPY_MC */
799
800 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
801 {
802 char *to = addr;
803 if (unlikely(iov_iter_is_pipe(i))) {
804 WARN_ON(1);
805 return 0;
806 }
807 if (iter_is_iovec(i))
808 might_fault();
809 iterate_and_advance(i, bytes, v,
810 copyin((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
811 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
812 v.bv_offset, v.bv_len),
813 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
814 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
815 v.bv_offset, v.bv_len)
816 )
817
818 return bytes;
819 }
820 EXPORT_SYMBOL(_copy_from_iter);
821
822 bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
823 {
824 char *to = addr;
825 if (unlikely(iov_iter_is_pipe(i))) {
826 WARN_ON(1);
827 return false;
828 }
829 if (unlikely(i->count < bytes))
830 return false;
831
832 if (iter_is_iovec(i))
833 might_fault();
834 iterate_all_kinds(i, bytes, v, ({
835 if (copyin((to += v.iov_len) - v.iov_len,
836 v.iov_base, v.iov_len))
837 return false;
838 0;}),
839 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
840 v.bv_offset, v.bv_len),
841 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
842 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
843 v.bv_offset, v.bv_len)
844 )
845
846 iov_iter_advance(i, bytes);
847 return true;
848 }
849 EXPORT_SYMBOL(_copy_from_iter_full);
850
851 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
852 {
853 char *to = addr;
854 if (unlikely(iov_iter_is_pipe(i))) {
855 WARN_ON(1);
856 return 0;
857 }
858 iterate_and_advance(i, bytes, v,
859 __copy_from_user_inatomic_nocache((to += v.iov_len) - v.iov_len,
860 v.iov_base, v.iov_len),
861 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
862 v.bv_offset, v.bv_len),
863 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
864 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
865 v.bv_offset, v.bv_len)
866 )
867
868 return bytes;
869 }
870 EXPORT_SYMBOL(_copy_from_iter_nocache);
871
872 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
873 /**
874 * _copy_from_iter_flushcache - write destination through cpu cache
875 * @addr: destination kernel address
876 * @bytes: total transfer length
877 * @iter: source iterator
878 *
879 * The pmem driver arranges for filesystem-dax to use this facility via
880 * dax_copy_from_iter() for ensuring that writes to persistent memory
881 * are flushed through the CPU cache. It is differentiated from
882 * _copy_from_iter_nocache() in that guarantees all data is flushed for
883 * all iterator types. The _copy_from_iter_nocache() only attempts to
884 * bypass the cache for the ITER_IOVEC case, and on some archs may use
885 * instructions that strand dirty-data in the cache.
886 */
887 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
888 {
889 char *to = addr;
890 if (unlikely(iov_iter_is_pipe(i))) {
891 WARN_ON(1);
892 return 0;
893 }
894 iterate_and_advance(i, bytes, v,
895 __copy_from_user_flushcache((to += v.iov_len) - v.iov_len,
896 v.iov_base, v.iov_len),
897 memcpy_page_flushcache((to += v.bv_len) - v.bv_len, v.bv_page,
898 v.bv_offset, v.bv_len),
899 memcpy_flushcache((to += v.iov_len) - v.iov_len, v.iov_base,
900 v.iov_len),
901 memcpy_page_flushcache((to += v.bv_len) - v.bv_len, v.bv_page,
902 v.bv_offset, v.bv_len)
903 )
904
905 return bytes;
906 }
907 EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache);
908 #endif
909
910 bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
911 {
912 char *to = addr;
913 if (unlikely(iov_iter_is_pipe(i))) {
914 WARN_ON(1);
915 return false;
916 }
917 if (unlikely(i->count < bytes))
918 return false;
919 iterate_all_kinds(i, bytes, v, ({
920 if (__copy_from_user_inatomic_nocache((to += v.iov_len) - v.iov_len,
921 v.iov_base, v.iov_len))
922 return false;
923 0;}),
924 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
925 v.bv_offset, v.bv_len),
926 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
927 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
928 v.bv_offset, v.bv_len)
929 )
930
931 iov_iter_advance(i, bytes);
932 return true;
933 }
934 EXPORT_SYMBOL(_copy_from_iter_full_nocache);
935
936 static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
937 {
938 struct page *head;
939 size_t v = n + offset;
940
941 /*
942 * The general case needs to access the page order in order
943 * to compute the page size.
944 * However, we mostly deal with order-0 pages and thus can
945 * avoid a possible cache line miss for requests that fit all
946 * page orders.
947 */
948 if (n <= v && v <= PAGE_SIZE)
949 return true;
950
951 head = compound_head(page);
952 v += (page - head) << PAGE_SHIFT;
953
954 if (likely(n <= v && v <= (page_size(head))))
955 return true;
956 WARN_ON(1);
957 return false;
958 }
959
960 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
961 struct iov_iter *i)
962 {
963 if (unlikely(!page_copy_sane(page, offset, bytes)))
964 return 0;
965 if (i->type & (ITER_BVEC | ITER_KVEC | ITER_XARRAY)) {
966 void *kaddr = kmap_atomic(page);
967 size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
968 kunmap_atomic(kaddr);
969 return wanted;
970 } else if (unlikely(iov_iter_is_discard(i)))
971 return bytes;
972 else if (likely(!iov_iter_is_pipe(i)))
973 return copy_page_to_iter_iovec(page, offset, bytes, i);
974 else
975 return copy_page_to_iter_pipe(page, offset, bytes, i);
976 }
977 EXPORT_SYMBOL(copy_page_to_iter);
978
979 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
980 struct iov_iter *i)
981 {
982 if (unlikely(!page_copy_sane(page, offset, bytes)))
983 return 0;
984 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
985 WARN_ON(1);
986 return 0;
987 }
988 if (i->type & (ITER_BVEC | ITER_KVEC | ITER_XARRAY)) {
989 void *kaddr = kmap_atomic(page);
990 size_t wanted = _copy_from_iter(kaddr + offset, bytes, i);
991 kunmap_atomic(kaddr);
992 return wanted;
993 } else
994 return copy_page_from_iter_iovec(page, offset, bytes, i);
995 }
996 EXPORT_SYMBOL(copy_page_from_iter);
997
998 static size_t pipe_zero(size_t bytes, struct iov_iter *i)
999 {
1000 struct pipe_inode_info *pipe = i->pipe;
1001 unsigned int p_mask = pipe->ring_size - 1;
1002 unsigned int i_head;
1003 size_t n, off;
1004
1005 if (!sanity(i))
1006 return 0;
1007
1008 bytes = n = push_pipe(i, bytes, &i_head, &off);
1009 if (unlikely(!n))
1010 return 0;
1011
1012 do {
1013 size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
1014 memzero_page(pipe->bufs[i_head & p_mask].page, off, chunk);
1015 i->head = i_head;
1016 i->iov_offset = off + chunk;
1017 n -= chunk;
1018 off = 0;
1019 i_head++;
1020 } while (n);
1021 i->count -= bytes;
1022 return bytes;
1023 }
1024
1025 size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
1026 {
1027 if (unlikely(iov_iter_is_pipe(i)))
1028 return pipe_zero(bytes, i);
1029 iterate_and_advance(i, bytes, v,
1030 clear_user(v.iov_base, v.iov_len),
1031 memzero_page(v.bv_page, v.bv_offset, v.bv_len),
1032 memset(v.iov_base, 0, v.iov_len),
1033 memzero_page(v.bv_page, v.bv_offset, v.bv_len)
1034 )
1035
1036 return bytes;
1037 }
1038 EXPORT_SYMBOL(iov_iter_zero);
1039
1040 size_t iov_iter_copy_from_user_atomic(struct page *page,
1041 struct iov_iter *i, unsigned long offset, size_t bytes)
1042 {
1043 char *kaddr = kmap_atomic(page), *p = kaddr + offset;
1044 if (unlikely(!page_copy_sane(page, offset, bytes))) {
1045 kunmap_atomic(kaddr);
1046 return 0;
1047 }
1048 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
1049 kunmap_atomic(kaddr);
1050 WARN_ON(1);
1051 return 0;
1052 }
1053 iterate_all_kinds(i, bytes, v,
1054 copyin((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
1055 memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page,
1056 v.bv_offset, v.bv_len),
1057 memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
1058 memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page,
1059 v.bv_offset, v.bv_len)
1060 )
1061 kunmap_atomic(kaddr);
1062 return bytes;
1063 }
1064 EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
1065
1066 static inline void pipe_truncate(struct iov_iter *i)
1067 {
1068 struct pipe_inode_info *pipe = i->pipe;
1069 unsigned int p_tail = pipe->tail;
1070 unsigned int p_head = pipe->head;
1071 unsigned int p_mask = pipe->ring_size - 1;
1072
1073 if (!pipe_empty(p_head, p_tail)) {
1074 struct pipe_buffer *buf;
1075 unsigned int i_head = i->head;
1076 size_t off = i->iov_offset;
1077
1078 if (off) {
1079 buf = &pipe->bufs[i_head & p_mask];
1080 buf->len = off - buf->offset;
1081 i_head++;
1082 }
1083 while (p_head != i_head) {
1084 p_head--;
1085 pipe_buf_release(pipe, &pipe->bufs[p_head & p_mask]);
1086 }
1087
1088 pipe->head = p_head;
1089 }
1090 }
1091
1092 static void pipe_advance(struct iov_iter *i, size_t size)
1093 {
1094 struct pipe_inode_info *pipe = i->pipe;
1095 if (unlikely(i->count < size))
1096 size = i->count;
1097 if (size) {
1098 struct pipe_buffer *buf;
1099 unsigned int p_mask = pipe->ring_size - 1;
1100 unsigned int i_head = i->head;
1101 size_t off = i->iov_offset, left = size;
1102
1103 if (off) /* make it relative to the beginning of buffer */
1104 left += off - pipe->bufs[i_head & p_mask].offset;
1105 while (1) {
1106 buf = &pipe->bufs[i_head & p_mask];
1107 if (left <= buf->len)
1108 break;
1109 left -= buf->len;
1110 i_head++;
1111 }
1112 i->head = i_head;
1113 i->iov_offset = buf->offset + left;
1114 }
1115 i->count -= size;
1116 /* ... and discard everything past that point */
1117 pipe_truncate(i);
1118 }
1119
1120 static void iov_iter_bvec_advance(struct iov_iter *i, size_t size)
1121 {
1122 struct bvec_iter bi;
1123
1124 bi.bi_size = i->count;
1125 bi.bi_bvec_done = i->iov_offset;
1126 bi.bi_idx = 0;
1127 bvec_iter_advance(i->bvec, &bi, size);
1128
1129 i->bvec += bi.bi_idx;
1130 i->nr_segs -= bi.bi_idx;
1131 i->count = bi.bi_size;
1132 i->iov_offset = bi.bi_bvec_done;
1133 }
1134
1135 void iov_iter_advance(struct iov_iter *i, size_t size)
1136 {
1137 if (unlikely(iov_iter_is_pipe(i))) {
1138 pipe_advance(i, size);
1139 return;
1140 }
1141 if (unlikely(iov_iter_is_discard(i))) {
1142 i->count -= size;
1143 return;
1144 }
1145 if (unlikely(iov_iter_is_xarray(i))) {
1146 size = min(size, i->count);
1147 i->iov_offset += size;
1148 i->count -= size;
1149 return;
1150 }
1151 if (iov_iter_is_bvec(i)) {
1152 iov_iter_bvec_advance(i, size);
1153 return;
1154 }
1155 iterate_and_advance(i, size, v, 0, 0, 0, 0)
1156 }
1157 EXPORT_SYMBOL(iov_iter_advance);
1158
1159 void iov_iter_revert(struct iov_iter *i, size_t unroll)
1160 {
1161 if (!unroll)
1162 return;
1163 if (WARN_ON(unroll > MAX_RW_COUNT))
1164 return;
1165 i->count += unroll;
1166 if (unlikely(iov_iter_is_pipe(i))) {
1167 struct pipe_inode_info *pipe = i->pipe;
1168 unsigned int p_mask = pipe->ring_size - 1;
1169 unsigned int i_head = i->head;
1170 size_t off = i->iov_offset;
1171 while (1) {
1172 struct pipe_buffer *b = &pipe->bufs[i_head & p_mask];
1173 size_t n = off - b->offset;
1174 if (unroll < n) {
1175 off -= unroll;
1176 break;
1177 }
1178 unroll -= n;
1179 if (!unroll && i_head == i->start_head) {
1180 off = 0;
1181 break;
1182 }
1183 i_head--;
1184 b = &pipe->bufs[i_head & p_mask];
1185 off = b->offset + b->len;
1186 }
1187 i->iov_offset = off;
1188 i->head = i_head;
1189 pipe_truncate(i);
1190 return;
1191 }
1192 if (unlikely(iov_iter_is_discard(i)))
1193 return;
1194 if (unroll <= i->iov_offset) {
1195 i->iov_offset -= unroll;
1196 return;
1197 }
1198 unroll -= i->iov_offset;
1199 if (iov_iter_is_xarray(i)) {
1200 BUG(); /* We should never go beyond the start of the specified
1201 * range since we might then be straying into pages that
1202 * aren't pinned.
1203 */
1204 } else if (iov_iter_is_bvec(i)) {
1205 const struct bio_vec *bvec = i->bvec;
1206 while (1) {
1207 size_t n = (--bvec)->bv_len;
1208 i->nr_segs++;
1209 if (unroll <= n) {
1210 i->bvec = bvec;
1211 i->iov_offset = n - unroll;
1212 return;
1213 }
1214 unroll -= n;
1215 }
1216 } else { /* same logics for iovec and kvec */
1217 const struct iovec *iov = i->iov;
1218 while (1) {
1219 size_t n = (--iov)->iov_len;
1220 i->nr_segs++;
1221 if (unroll <= n) {
1222 i->iov = iov;
1223 i->iov_offset = n - unroll;
1224 return;
1225 }
1226 unroll -= n;
1227 }
1228 }
1229 }
1230 EXPORT_SYMBOL(iov_iter_revert);
1231
1232 /*
1233 * Return the count of just the current iov_iter segment.
1234 */
1235 size_t iov_iter_single_seg_count(const struct iov_iter *i)
1236 {
1237 if (unlikely(iov_iter_is_pipe(i)))
1238 return i->count; // it is a silly place, anyway
1239 if (i->nr_segs == 1)
1240 return i->count;
1241 if (unlikely(iov_iter_is_discard(i) || iov_iter_is_xarray(i)))
1242 return i->count;
1243 if (iov_iter_is_bvec(i))
1244 return min(i->count, i->bvec->bv_len - i->iov_offset);
1245 else
1246 return min(i->count, i->iov->iov_len - i->iov_offset);
1247 }
1248 EXPORT_SYMBOL(iov_iter_single_seg_count);
1249
1250 void iov_iter_kvec(struct iov_iter *i, unsigned int direction,
1251 const struct kvec *kvec, unsigned long nr_segs,
1252 size_t count)
1253 {
1254 WARN_ON(direction & ~(READ | WRITE));
1255 i->type = ITER_KVEC | (direction & (READ | WRITE));
1256 i->kvec = kvec;
1257 i->nr_segs = nr_segs;
1258 i->iov_offset = 0;
1259 i->count = count;
1260 }
1261 EXPORT_SYMBOL(iov_iter_kvec);
1262
1263 void iov_iter_bvec(struct iov_iter *i, unsigned int direction,
1264 const struct bio_vec *bvec, unsigned long nr_segs,
1265 size_t count)
1266 {
1267 WARN_ON(direction & ~(READ | WRITE));
1268 i->type = ITER_BVEC | (direction & (READ | WRITE));
1269 i->bvec = bvec;
1270 i->nr_segs = nr_segs;
1271 i->iov_offset = 0;
1272 i->count = count;
1273 }
1274 EXPORT_SYMBOL(iov_iter_bvec);
1275
1276 void iov_iter_pipe(struct iov_iter *i, unsigned int direction,
1277 struct pipe_inode_info *pipe,
1278 size_t count)
1279 {
1280 BUG_ON(direction != READ);
1281 WARN_ON(pipe_full(pipe->head, pipe->tail, pipe->ring_size));
1282 i->type = ITER_PIPE | READ;
1283 i->pipe = pipe;
1284 i->head = pipe->head;
1285 i->iov_offset = 0;
1286 i->count = count;
1287 i->start_head = i->head;
1288 }
1289 EXPORT_SYMBOL(iov_iter_pipe);
1290
1291 /**
1292 * iov_iter_xarray - Initialise an I/O iterator to use the pages in an xarray
1293 * @i: The iterator to initialise.
1294 * @direction: The direction of the transfer.
1295 * @xarray: The xarray to access.
1296 * @start: The start file position.
1297 * @count: The size of the I/O buffer in bytes.
1298 *
1299 * Set up an I/O iterator to either draw data out of the pages attached to an
1300 * inode or to inject data into those pages. The pages *must* be prevented
1301 * from evaporation, either by taking a ref on them or locking them by the
1302 * caller.
1303 */
1304 void iov_iter_xarray(struct iov_iter *i, unsigned int direction,
1305 struct xarray *xarray, loff_t start, size_t count)
1306 {
1307 BUG_ON(direction & ~1);
1308 i->type = ITER_XARRAY | (direction & (READ | WRITE));
1309 i->xarray = xarray;
1310 i->xarray_start = start;
1311 i->count = count;
1312 i->iov_offset = 0;
1313 }
1314 EXPORT_SYMBOL(iov_iter_xarray);
1315
1316 /**
1317 * iov_iter_discard - Initialise an I/O iterator that discards data
1318 * @i: The iterator to initialise.
1319 * @direction: The direction of the transfer.
1320 * @count: The size of the I/O buffer in bytes.
1321 *
1322 * Set up an I/O iterator that just discards everything that's written to it.
1323 * It's only available as a READ iterator.
1324 */
1325 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count)
1326 {
1327 BUG_ON(direction != READ);
1328 i->type = ITER_DISCARD | READ;
1329 i->count = count;
1330 i->iov_offset = 0;
1331 }
1332 EXPORT_SYMBOL(iov_iter_discard);
1333
1334 unsigned long iov_iter_alignment(const struct iov_iter *i)
1335 {
1336 unsigned long res = 0;
1337 size_t size = i->count;
1338
1339 if (unlikely(iov_iter_is_pipe(i))) {
1340 unsigned int p_mask = i->pipe->ring_size - 1;
1341
1342 if (size && i->iov_offset && allocated(&i->pipe->bufs[i->head & p_mask]))
1343 return size | i->iov_offset;
1344 return size;
1345 }
1346 if (unlikely(iov_iter_is_xarray(i)))
1347 return (i->xarray_start + i->iov_offset) | i->count;
1348 iterate_all_kinds(i, size, v,
1349 (res |= (unsigned long)v.iov_base | v.iov_len, 0),
1350 res |= v.bv_offset | v.bv_len,
1351 res |= (unsigned long)v.iov_base | v.iov_len,
1352 res |= v.bv_offset | v.bv_len
1353 )
1354 return res;
1355 }
1356 EXPORT_SYMBOL(iov_iter_alignment);
1357
1358 unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
1359 {
1360 unsigned long res = 0;
1361 size_t size = i->count;
1362
1363 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
1364 WARN_ON(1);
1365 return ~0U;
1366 }
1367
1368 iterate_all_kinds(i, size, v,
1369 (res |= (!res ? 0 : (unsigned long)v.iov_base) |
1370 (size != v.iov_len ? size : 0), 0),
1371 (res |= (!res ? 0 : (unsigned long)v.bv_offset) |
1372 (size != v.bv_len ? size : 0)),
1373 (res |= (!res ? 0 : (unsigned long)v.iov_base) |
1374 (size != v.iov_len ? size : 0)),
1375 (res |= (!res ? 0 : (unsigned long)v.bv_offset) |
1376 (size != v.bv_len ? size : 0))
1377 );
1378 return res;
1379 }
1380 EXPORT_SYMBOL(iov_iter_gap_alignment);
1381
1382 static inline ssize_t __pipe_get_pages(struct iov_iter *i,
1383 size_t maxsize,
1384 struct page **pages,
1385 int iter_head,
1386 size_t *start)
1387 {
1388 struct pipe_inode_info *pipe = i->pipe;
1389 unsigned int p_mask = pipe->ring_size - 1;
1390 ssize_t n = push_pipe(i, maxsize, &iter_head, start);
1391 if (!n)
1392 return -EFAULT;
1393
1394 maxsize = n;
1395 n += *start;
1396 while (n > 0) {
1397 get_page(*pages++ = pipe->bufs[iter_head & p_mask].page);
1398 iter_head++;
1399 n -= PAGE_SIZE;
1400 }
1401
1402 return maxsize;
1403 }
1404
1405 static ssize_t pipe_get_pages(struct iov_iter *i,
1406 struct page **pages, size_t maxsize, unsigned maxpages,
1407 size_t *start)
1408 {
1409 unsigned int iter_head, npages;
1410 size_t capacity;
1411
1412 if (!maxsize)
1413 return 0;
1414
1415 if (!sanity(i))
1416 return -EFAULT;
1417
1418 data_start(i, &iter_head, start);
1419 /* Amount of free space: some of this one + all after this one */
1420 npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
1421 capacity = min(npages, maxpages) * PAGE_SIZE - *start;
1422
1423 return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, start);
1424 }
1425
1426 static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa,
1427 pgoff_t index, unsigned int nr_pages)
1428 {
1429 XA_STATE(xas, xa, index);
1430 struct page *page;
1431 unsigned int ret = 0;
1432
1433 rcu_read_lock();
1434 for (page = xas_load(&xas); page; page = xas_next(&xas)) {
1435 if (xas_retry(&xas, page))
1436 continue;
1437
1438 /* Has the page moved or been split? */
1439 if (unlikely(page != xas_reload(&xas))) {
1440 xas_reset(&xas);
1441 continue;
1442 }
1443
1444 pages[ret] = find_subpage(page, xas.xa_index);
1445 get_page(pages[ret]);
1446 if (++ret == nr_pages)
1447 break;
1448 }
1449 rcu_read_unlock();
1450 return ret;
1451 }
1452
1453 static ssize_t iter_xarray_get_pages(struct iov_iter *i,
1454 struct page **pages, size_t maxsize,
1455 unsigned maxpages, size_t *_start_offset)
1456 {
1457 unsigned nr, offset;
1458 pgoff_t index, count;
1459 size_t size = maxsize, actual;
1460 loff_t pos;
1461
1462 if (!size || !maxpages)
1463 return 0;
1464
1465 pos = i->xarray_start + i->iov_offset;
1466 index = pos >> PAGE_SHIFT;
1467 offset = pos & ~PAGE_MASK;
1468 *_start_offset = offset;
1469
1470 count = 1;
1471 if (size > PAGE_SIZE - offset) {
1472 size -= PAGE_SIZE - offset;
1473 count += size >> PAGE_SHIFT;
1474 size &= ~PAGE_MASK;
1475 if (size)
1476 count++;
1477 }
1478
1479 if (count > maxpages)
1480 count = maxpages;
1481
1482 nr = iter_xarray_populate_pages(pages, i->xarray, index, count);
1483 if (nr == 0)
1484 return 0;
1485
1486 actual = PAGE_SIZE * nr;
1487 actual -= offset;
1488 if (nr == count && size > 0) {
1489 unsigned last_offset = (nr > 1) ? 0 : offset;
1490 actual -= PAGE_SIZE - (last_offset + size);
1491 }
1492 return actual;
1493 }
1494
1495 ssize_t iov_iter_get_pages(struct iov_iter *i,
1496 struct page **pages, size_t maxsize, unsigned maxpages,
1497 size_t *start)
1498 {
1499 if (maxsize > i->count)
1500 maxsize = i->count;
1501
1502 if (unlikely(iov_iter_is_pipe(i)))
1503 return pipe_get_pages(i, pages, maxsize, maxpages, start);
1504 if (unlikely(iov_iter_is_xarray(i)))
1505 return iter_xarray_get_pages(i, pages, maxsize, maxpages, start);
1506 if (unlikely(iov_iter_is_discard(i)))
1507 return -EFAULT;
1508
1509 iterate_all_kinds(i, maxsize, v, ({
1510 unsigned long addr = (unsigned long)v.iov_base;
1511 size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
1512 int n;
1513 int res;
1514
1515 if (len > maxpages * PAGE_SIZE)
1516 len = maxpages * PAGE_SIZE;
1517 addr &= ~(PAGE_SIZE - 1);
1518 n = DIV_ROUND_UP(len, PAGE_SIZE);
1519 res = get_user_pages_fast(addr, n,
1520 iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0,
1521 pages);
1522 if (unlikely(res < 0))
1523 return res;
1524 return (res == n ? len : res * PAGE_SIZE) - *start;
1525 0;}),({
1526 /* can't be more than PAGE_SIZE */
1527 *start = v.bv_offset;
1528 get_page(*pages = v.bv_page);
1529 return v.bv_len;
1530 }),({
1531 return -EFAULT;
1532 }),
1533 0
1534 )
1535 return 0;
1536 }
1537 EXPORT_SYMBOL(iov_iter_get_pages);
1538
1539 static struct page **get_pages_array(size_t n)
1540 {
1541 return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL);
1542 }
1543
1544 static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
1545 struct page ***pages, size_t maxsize,
1546 size_t *start)
1547 {
1548 struct page **p;
1549 unsigned int iter_head, npages;
1550 ssize_t n;
1551
1552 if (!maxsize)
1553 return 0;
1554
1555 if (!sanity(i))
1556 return -EFAULT;
1557
1558 data_start(i, &iter_head, start);
1559 /* Amount of free space: some of this one + all after this one */
1560 npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
1561 n = npages * PAGE_SIZE - *start;
1562 if (maxsize > n)
1563 maxsize = n;
1564 else
1565 npages = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
1566 p = get_pages_array(npages);
1567 if (!p)
1568 return -ENOMEM;
1569 n = __pipe_get_pages(i, maxsize, p, iter_head, start);
1570 if (n > 0)
1571 *pages = p;
1572 else
1573 kvfree(p);
1574 return n;
1575 }
1576
1577 static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i,
1578 struct page ***pages, size_t maxsize,
1579 size_t *_start_offset)
1580 {
1581 struct page **p;
1582 unsigned nr, offset;
1583 pgoff_t index, count;
1584 size_t size = maxsize, actual;
1585 loff_t pos;
1586
1587 if (!size)
1588 return 0;
1589
1590 pos = i->xarray_start + i->iov_offset;
1591 index = pos >> PAGE_SHIFT;
1592 offset = pos & ~PAGE_MASK;
1593 *_start_offset = offset;
1594
1595 count = 1;
1596 if (size > PAGE_SIZE - offset) {
1597 size -= PAGE_SIZE - offset;
1598 count += size >> PAGE_SHIFT;
1599 size &= ~PAGE_MASK;
1600 if (size)
1601 count++;
1602 }
1603
1604 p = get_pages_array(count);
1605 if (!p)
1606 return -ENOMEM;
1607 *pages = p;
1608
1609 nr = iter_xarray_populate_pages(p, i->xarray, index, count);
1610 if (nr == 0)
1611 return 0;
1612
1613 actual = PAGE_SIZE * nr;
1614 actual -= offset;
1615 if (nr == count && size > 0) {
1616 unsigned last_offset = (nr > 1) ? 0 : offset;
1617 actual -= PAGE_SIZE - (last_offset + size);
1618 }
1619 return actual;
1620 }
1621
1622 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
1623 struct page ***pages, size_t maxsize,
1624 size_t *start)
1625 {
1626 struct page **p;
1627
1628 if (maxsize > i->count)
1629 maxsize = i->count;
1630
1631 if (unlikely(iov_iter_is_pipe(i)))
1632 return pipe_get_pages_alloc(i, pages, maxsize, start);
1633 if (unlikely(iov_iter_is_xarray(i)))
1634 return iter_xarray_get_pages_alloc(i, pages, maxsize, start);
1635 if (unlikely(iov_iter_is_discard(i)))
1636 return -EFAULT;
1637
1638 iterate_all_kinds(i, maxsize, v, ({
1639 unsigned long addr = (unsigned long)v.iov_base;
1640 size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
1641 int n;
1642 int res;
1643
1644 addr &= ~(PAGE_SIZE - 1);
1645 n = DIV_ROUND_UP(len, PAGE_SIZE);
1646 p = get_pages_array(n);
1647 if (!p)
1648 return -ENOMEM;
1649 res = get_user_pages_fast(addr, n,
1650 iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0, p);
1651 if (unlikely(res < 0)) {
1652 kvfree(p);
1653 return res;
1654 }
1655 *pages = p;
1656 return (res == n ? len : res * PAGE_SIZE) - *start;
1657 0;}),({
1658 /* can't be more than PAGE_SIZE */
1659 *start = v.bv_offset;
1660 *pages = p = get_pages_array(1);
1661 if (!p)
1662 return -ENOMEM;
1663 get_page(*p = v.bv_page);
1664 return v.bv_len;
1665 }),({
1666 return -EFAULT;
1667 }), 0
1668 )
1669 return 0;
1670 }
1671 EXPORT_SYMBOL(iov_iter_get_pages_alloc);
1672
1673 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
1674 struct iov_iter *i)
1675 {
1676 char *to = addr;
1677 __wsum sum, next;
1678 size_t off = 0;
1679 sum = *csum;
1680 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
1681 WARN_ON(1);
1682 return 0;
1683 }
1684 iterate_and_advance(i, bytes, v, ({
1685 next = csum_and_copy_from_user(v.iov_base,
1686 (to += v.iov_len) - v.iov_len,
1687 v.iov_len);
1688 if (next) {
1689 sum = csum_block_add(sum, next, off);
1690 off += v.iov_len;
1691 }
1692 next ? 0 : v.iov_len;
1693 }), ({
1694 char *p = kmap_atomic(v.bv_page);
1695 sum = csum_and_memcpy((to += v.bv_len) - v.bv_len,
1696 p + v.bv_offset, v.bv_len,
1697 sum, off);
1698 kunmap_atomic(p);
1699 off += v.bv_len;
1700 }),({
1701 sum = csum_and_memcpy((to += v.iov_len) - v.iov_len,
1702 v.iov_base, v.iov_len,
1703 sum, off);
1704 off += v.iov_len;
1705 }), ({
1706 char *p = kmap_atomic(v.bv_page);
1707 sum = csum_and_memcpy((to += v.bv_len) - v.bv_len,
1708 p + v.bv_offset, v.bv_len,
1709 sum, off);
1710 kunmap_atomic(p);
1711 off += v.bv_len;
1712 })
1713 )
1714 *csum = sum;
1715 return bytes;
1716 }
1717 EXPORT_SYMBOL(csum_and_copy_from_iter);
1718
1719 bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum,
1720 struct iov_iter *i)
1721 {
1722 char *to = addr;
1723 __wsum sum, next;
1724 size_t off = 0;
1725 sum = *csum;
1726 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
1727 WARN_ON(1);
1728 return false;
1729 }
1730 if (unlikely(i->count < bytes))
1731 return false;
1732 iterate_all_kinds(i, bytes, v, ({
1733 next = csum_and_copy_from_user(v.iov_base,
1734 (to += v.iov_len) - v.iov_len,
1735 v.iov_len);
1736 if (!next)
1737 return false;
1738 sum = csum_block_add(sum, next, off);
1739 off += v.iov_len;
1740 0;
1741 }), ({
1742 char *p = kmap_atomic(v.bv_page);
1743 sum = csum_and_memcpy((to += v.bv_len) - v.bv_len,
1744 p + v.bv_offset, v.bv_len,
1745 sum, off);
1746 kunmap_atomic(p);
1747 off += v.bv_len;
1748 }),({
1749 sum = csum_and_memcpy((to += v.iov_len) - v.iov_len,
1750 v.iov_base, v.iov_len,
1751 sum, off);
1752 off += v.iov_len;
1753 }), ({
1754 char *p = kmap_atomic(v.bv_page);
1755 sum = csum_and_memcpy((to += v.bv_len) - v.bv_len,
1756 p + v.bv_offset, v.bv_len,
1757 sum, off);
1758 kunmap_atomic(p);
1759 off += v.bv_len;
1760 })
1761 )
1762 *csum = sum;
1763 iov_iter_advance(i, bytes);
1764 return true;
1765 }
1766 EXPORT_SYMBOL(csum_and_copy_from_iter_full);
1767
1768 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate,
1769 struct iov_iter *i)
1770 {
1771 struct csum_state *csstate = _csstate;
1772 const char *from = addr;
1773 __wsum sum, next;
1774 size_t off;
1775
1776 if (unlikely(iov_iter_is_pipe(i)))
1777 return csum_and_copy_to_pipe_iter(addr, bytes, _csstate, i);
1778
1779 sum = csstate->csum;
1780 off = csstate->off;
1781 if (unlikely(iov_iter_is_discard(i))) {
1782 WARN_ON(1); /* for now */
1783 return 0;
1784 }
1785 iterate_and_advance(i, bytes, v, ({
1786 next = csum_and_copy_to_user((from += v.iov_len) - v.iov_len,
1787 v.iov_base,
1788 v.iov_len);
1789 if (next) {
1790 sum = csum_block_add(sum, next, off);
1791 off += v.iov_len;
1792 }
1793 next ? 0 : v.iov_len;
1794 }), ({
1795 char *p = kmap_atomic(v.bv_page);
1796 sum = csum_and_memcpy(p + v.bv_offset,
1797 (from += v.bv_len) - v.bv_len,
1798 v.bv_len, sum, off);
1799 kunmap_atomic(p);
1800 off += v.bv_len;
1801 }),({
1802 sum = csum_and_memcpy(v.iov_base,
1803 (from += v.iov_len) - v.iov_len,
1804 v.iov_len, sum, off);
1805 off += v.iov_len;
1806 }), ({
1807 char *p = kmap_atomic(v.bv_page);
1808 sum = csum_and_memcpy(p + v.bv_offset,
1809 (from += v.bv_len) - v.bv_len,
1810 v.bv_len, sum, off);
1811 kunmap_atomic(p);
1812 off += v.bv_len;
1813 })
1814 )
1815 csstate->csum = sum;
1816 csstate->off = off;
1817 return bytes;
1818 }
1819 EXPORT_SYMBOL(csum_and_copy_to_iter);
1820
1821 size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
1822 struct iov_iter *i)
1823 {
1824 #ifdef CONFIG_CRYPTO_HASH
1825 struct ahash_request *hash = hashp;
1826 struct scatterlist sg;
1827 size_t copied;
1828
1829 copied = copy_to_iter(addr, bytes, i);
1830 sg_init_one(&sg, addr, copied);
1831 ahash_request_set_crypt(hash, &sg, NULL, copied);
1832 crypto_ahash_update(hash);
1833 return copied;
1834 #else
1835 return 0;
1836 #endif
1837 }
1838 EXPORT_SYMBOL(hash_and_copy_to_iter);
1839
1840 int iov_iter_npages(const struct iov_iter *i, int maxpages)
1841 {
1842 size_t size = i->count;
1843 int npages = 0;
1844
1845 if (!size)
1846 return 0;
1847 if (unlikely(iov_iter_is_discard(i)))
1848 return 0;
1849
1850 if (unlikely(iov_iter_is_pipe(i))) {
1851 struct pipe_inode_info *pipe = i->pipe;
1852 unsigned int iter_head;
1853 size_t off;
1854
1855 if (!sanity(i))
1856 return 0;
1857
1858 data_start(i, &iter_head, &off);
1859 /* some of this one + all after this one */
1860 npages = pipe_space_for_user(iter_head, pipe->tail, pipe);
1861 if (npages >= maxpages)
1862 return maxpages;
1863 } else if (unlikely(iov_iter_is_xarray(i))) {
1864 unsigned offset;
1865
1866 offset = (i->xarray_start + i->iov_offset) & ~PAGE_MASK;
1867
1868 npages = 1;
1869 if (size > PAGE_SIZE - offset) {
1870 size -= PAGE_SIZE - offset;
1871 npages += size >> PAGE_SHIFT;
1872 size &= ~PAGE_MASK;
1873 if (size)
1874 npages++;
1875 }
1876 if (npages >= maxpages)
1877 return maxpages;
1878 } else iterate_all_kinds(i, size, v, ({
1879 unsigned long p = (unsigned long)v.iov_base;
1880 npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
1881 - p / PAGE_SIZE;
1882 if (npages >= maxpages)
1883 return maxpages;
1884 0;}),({
1885 npages++;
1886 if (npages >= maxpages)
1887 return maxpages;
1888 }),({
1889 unsigned long p = (unsigned long)v.iov_base;
1890 npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
1891 - p / PAGE_SIZE;
1892 if (npages >= maxpages)
1893 return maxpages;
1894 }),
1895 0
1896 )
1897 return npages;
1898 }
1899 EXPORT_SYMBOL(iov_iter_npages);
1900
1901 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
1902 {
1903 *new = *old;
1904 if (unlikely(iov_iter_is_pipe(new))) {
1905 WARN_ON(1);
1906 return NULL;
1907 }
1908 if (unlikely(iov_iter_is_discard(new) || iov_iter_is_xarray(new)))
1909 return NULL;
1910 if (iov_iter_is_bvec(new))
1911 return new->bvec = kmemdup(new->bvec,
1912 new->nr_segs * sizeof(struct bio_vec),
1913 flags);
1914 else
1915 /* iovec and kvec have identical layout */
1916 return new->iov = kmemdup(new->iov,
1917 new->nr_segs * sizeof(struct iovec),
1918 flags);
1919 }
1920 EXPORT_SYMBOL(dup_iter);
1921
1922 static int copy_compat_iovec_from_user(struct iovec *iov,
1923 const struct iovec __user *uvec, unsigned long nr_segs)
1924 {
1925 const struct compat_iovec __user *uiov =
1926 (const struct compat_iovec __user *)uvec;
1927 int ret = -EFAULT, i;
1928
1929 if (!user_access_begin(uiov, nr_segs * sizeof(*uiov)))
1930 return -EFAULT;
1931
1932 for (i = 0; i < nr_segs; i++) {
1933 compat_uptr_t buf;
1934 compat_ssize_t len;
1935
1936 unsafe_get_user(len, &uiov[i].iov_len, uaccess_end);
1937 unsafe_get_user(buf, &uiov[i].iov_base, uaccess_end);
1938
1939 /* check for compat_size_t not fitting in compat_ssize_t .. */
1940 if (len < 0) {
1941 ret = -EINVAL;
1942 goto uaccess_end;
1943 }
1944 iov[i].iov_base = compat_ptr(buf);
1945 iov[i].iov_len = len;
1946 }
1947
1948 ret = 0;
1949 uaccess_end:
1950 user_access_end();
1951 return ret;
1952 }
1953
1954 static int copy_iovec_from_user(struct iovec *iov,
1955 const struct iovec __user *uvec, unsigned long nr_segs)
1956 {
1957 unsigned long seg;
1958
1959 if (copy_from_user(iov, uvec, nr_segs * sizeof(*uvec)))
1960 return -EFAULT;
1961 for (seg = 0; seg < nr_segs; seg++) {
1962 if ((ssize_t)iov[seg].iov_len < 0)
1963 return -EINVAL;
1964 }
1965
1966 return 0;
1967 }
1968
1969 struct iovec *iovec_from_user(const struct iovec __user *uvec,
1970 unsigned long nr_segs, unsigned long fast_segs,
1971 struct iovec *fast_iov, bool compat)
1972 {
1973 struct iovec *iov = fast_iov;
1974 int ret;
1975
1976 /*
1977 * SuS says "The readv() function *may* fail if the iovcnt argument was
1978 * less than or equal to 0, or greater than {IOV_MAX}. Linux has
1979 * traditionally returned zero for zero segments, so...
1980 */
1981 if (nr_segs == 0)
1982 return iov;
1983 if (nr_segs > UIO_MAXIOV)
1984 return ERR_PTR(-EINVAL);
1985 if (nr_segs > fast_segs) {
1986 iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL);
1987 if (!iov)
1988 return ERR_PTR(-ENOMEM);
1989 }
1990
1991 if (compat)
1992 ret = copy_compat_iovec_from_user(iov, uvec, nr_segs);
1993 else
1994 ret = copy_iovec_from_user(iov, uvec, nr_segs);
1995 if (ret) {
1996 if (iov != fast_iov)
1997 kfree(iov);
1998 return ERR_PTR(ret);
1999 }
2000
2001 return iov;
2002 }
2003
2004 ssize_t __import_iovec(int type, const struct iovec __user *uvec,
2005 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
2006 struct iov_iter *i, bool compat)
2007 {
2008 ssize_t total_len = 0;
2009 unsigned long seg;
2010 struct iovec *iov;
2011
2012 iov = iovec_from_user(uvec, nr_segs, fast_segs, *iovp, compat);
2013 if (IS_ERR(iov)) {
2014 *iovp = NULL;
2015 return PTR_ERR(iov);
2016 }
2017
2018 /*
2019 * According to the Single Unix Specification we should return EINVAL if
2020 * an element length is < 0 when cast to ssize_t or if the total length
2021 * would overflow the ssize_t return value of the system call.
2022 *
2023 * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the
2024 * overflow case.
2025 */
2026 for (seg = 0; seg < nr_segs; seg++) {
2027 ssize_t len = (ssize_t)iov[seg].iov_len;
2028
2029 if (!access_ok(iov[seg].iov_base, len)) {
2030 if (iov != *iovp)
2031 kfree(iov);
2032 *iovp = NULL;
2033 return -EFAULT;
2034 }
2035
2036 if (len > MAX_RW_COUNT - total_len) {
2037 len = MAX_RW_COUNT - total_len;
2038 iov[seg].iov_len = len;
2039 }
2040 total_len += len;
2041 }
2042
2043 iov_iter_init(i, type, iov, nr_segs, total_len);
2044 if (iov == *iovp)
2045 *iovp = NULL;
2046 else
2047 *iovp = iov;
2048 return total_len;
2049 }
2050
2051 /**
2052 * import_iovec() - Copy an array of &struct iovec from userspace
2053 * into the kernel, check that it is valid, and initialize a new
2054 * &struct iov_iter iterator to access it.
2055 *
2056 * @type: One of %READ or %WRITE.
2057 * @uvec: Pointer to the userspace array.
2058 * @nr_segs: Number of elements in userspace array.
2059 * @fast_segs: Number of elements in @iov.
2060 * @iovp: (input and output parameter) Pointer to pointer to (usually small
2061 * on-stack) kernel array.
2062 * @i: Pointer to iterator that will be initialized on success.
2063 *
2064 * If the array pointed to by *@iov is large enough to hold all @nr_segs,
2065 * then this function places %NULL in *@iov on return. Otherwise, a new
2066 * array will be allocated and the result placed in *@iov. This means that
2067 * the caller may call kfree() on *@iov regardless of whether the small
2068 * on-stack array was used or not (and regardless of whether this function
2069 * returns an error or not).
2070 *
2071 * Return: Negative error code on error, bytes imported on success
2072 */
2073 ssize_t import_iovec(int type, const struct iovec __user *uvec,
2074 unsigned nr_segs, unsigned fast_segs,
2075 struct iovec **iovp, struct iov_iter *i)
2076 {
2077 return __import_iovec(type, uvec, nr_segs, fast_segs, iovp, i,
2078 in_compat_syscall());
2079 }
2080 EXPORT_SYMBOL(import_iovec);
2081
2082 int import_single_range(int rw, void __user *buf, size_t len,
2083 struct iovec *iov, struct iov_iter *i)
2084 {
2085 if (len > MAX_RW_COUNT)
2086 len = MAX_RW_COUNT;
2087 if (unlikely(!access_ok(buf, len)))
2088 return -EFAULT;
2089
2090 iov->iov_base = buf;
2091 iov->iov_len = len;
2092 iov_iter_init(i, rw, iov, 1, len);
2093 return 0;
2094 }
2095 EXPORT_SYMBOL(import_single_range);
2096
2097 int iov_iter_for_each_range(struct iov_iter *i, size_t bytes,
2098 int (*f)(struct kvec *vec, void *context),
2099 void *context)
2100 {
2101 struct kvec w;
2102 int err = -EINVAL;
2103 if (!bytes)
2104 return 0;
2105
2106 iterate_all_kinds(i, bytes, v, -EINVAL, ({
2107 w.iov_base = kmap(v.bv_page) + v.bv_offset;
2108 w.iov_len = v.bv_len;
2109 err = f(&w, context);
2110 kunmap(v.bv_page);
2111 err;}), ({
2112 w = v;
2113 err = f(&w, context);}), ({
2114 w.iov_base = kmap(v.bv_page) + v.bv_offset;
2115 w.iov_len = v.bv_len;
2116 err = f(&w, context);
2117 kunmap(v.bv_page);
2118 err;})
2119 )
2120 return err;
2121 }
2122 EXPORT_SYMBOL(iov_iter_for_each_range);
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