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Merge tag 'gcc-plugins-v4.20-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git...
[mirror_ubuntu-eoan-kernel.git] / lib / iov_iter.c
1 #include <linux/export.h>
2 #include <linux/bvec.h>
3 #include <linux/uio.h>
4 #include <linux/pagemap.h>
5 #include <linux/slab.h>
6 #include <linux/vmalloc.h>
7 #include <linux/splice.h>
8 #include <net/checksum.h>
9
10 #define PIPE_PARANOIA /* for now */
11
12 #define iterate_iovec(i, n, __v, __p, skip, STEP) { \
13 size_t left; \
14 size_t wanted = n; \
15 __p = i->iov; \
16 __v.iov_len = min(n, __p->iov_len - skip); \
17 if (likely(__v.iov_len)) { \
18 __v.iov_base = __p->iov_base + skip; \
19 left = (STEP); \
20 __v.iov_len -= left; \
21 skip += __v.iov_len; \
22 n -= __v.iov_len; \
23 } else { \
24 left = 0; \
25 } \
26 while (unlikely(!left && n)) { \
27 __p++; \
28 __v.iov_len = min(n, __p->iov_len); \
29 if (unlikely(!__v.iov_len)) \
30 continue; \
31 __v.iov_base = __p->iov_base; \
32 left = (STEP); \
33 __v.iov_len -= left; \
34 skip = __v.iov_len; \
35 n -= __v.iov_len; \
36 } \
37 n = wanted - n; \
38 }
39
40 #define iterate_kvec(i, n, __v, __p, skip, STEP) { \
41 size_t wanted = n; \
42 __p = i->kvec; \
43 __v.iov_len = min(n, __p->iov_len - skip); \
44 if (likely(__v.iov_len)) { \
45 __v.iov_base = __p->iov_base + skip; \
46 (void)(STEP); \
47 skip += __v.iov_len; \
48 n -= __v.iov_len; \
49 } \
50 while (unlikely(n)) { \
51 __p++; \
52 __v.iov_len = min(n, __p->iov_len); \
53 if (unlikely(!__v.iov_len)) \
54 continue; \
55 __v.iov_base = __p->iov_base; \
56 (void)(STEP); \
57 skip = __v.iov_len; \
58 n -= __v.iov_len; \
59 } \
60 n = wanted; \
61 }
62
63 #define iterate_bvec(i, n, __v, __bi, skip, STEP) { \
64 struct bvec_iter __start; \
65 __start.bi_size = n; \
66 __start.bi_bvec_done = skip; \
67 __start.bi_idx = 0; \
68 for_each_bvec(__v, i->bvec, __bi, __start) { \
69 if (!__v.bv_len) \
70 continue; \
71 (void)(STEP); \
72 } \
73 }
74
75 #define iterate_all_kinds(i, n, v, I, B, K) { \
76 if (likely(n)) { \
77 size_t skip = i->iov_offset; \
78 if (unlikely(i->type & ITER_BVEC)) { \
79 struct bio_vec v; \
80 struct bvec_iter __bi; \
81 iterate_bvec(i, n, v, __bi, skip, (B)) \
82 } else if (unlikely(i->type & ITER_KVEC)) { \
83 const struct kvec *kvec; \
84 struct kvec v; \
85 iterate_kvec(i, n, v, kvec, skip, (K)) \
86 } else if (unlikely(i->type & ITER_DISCARD)) { \
87 } else { \
88 const struct iovec *iov; \
89 struct iovec v; \
90 iterate_iovec(i, n, v, iov, skip, (I)) \
91 } \
92 } \
93 }
94
95 #define iterate_and_advance(i, n, v, I, B, K) { \
96 if (unlikely(i->count < n)) \
97 n = i->count; \
98 if (i->count) { \
99 size_t skip = i->iov_offset; \
100 if (unlikely(i->type & ITER_BVEC)) { \
101 const struct bio_vec *bvec = i->bvec; \
102 struct bio_vec v; \
103 struct bvec_iter __bi; \
104 iterate_bvec(i, n, v, __bi, skip, (B)) \
105 i->bvec = __bvec_iter_bvec(i->bvec, __bi); \
106 i->nr_segs -= i->bvec - bvec; \
107 skip = __bi.bi_bvec_done; \
108 } else if (unlikely(i->type & ITER_KVEC)) { \
109 const struct kvec *kvec; \
110 struct kvec v; \
111 iterate_kvec(i, n, v, kvec, skip, (K)) \
112 if (skip == kvec->iov_len) { \
113 kvec++; \
114 skip = 0; \
115 } \
116 i->nr_segs -= kvec - i->kvec; \
117 i->kvec = kvec; \
118 } else if (unlikely(i->type & ITER_DISCARD)) { \
119 skip += n; \
120 } else { \
121 const struct iovec *iov; \
122 struct iovec v; \
123 iterate_iovec(i, n, v, iov, skip, (I)) \
124 if (skip == iov->iov_len) { \
125 iov++; \
126 skip = 0; \
127 } \
128 i->nr_segs -= iov - i->iov; \
129 i->iov = iov; \
130 } \
131 i->count -= n; \
132 i->iov_offset = skip; \
133 } \
134 }
135
136 static int copyout(void __user *to, const void *from, size_t n)
137 {
138 if (access_ok(VERIFY_WRITE, to, n)) {
139 kasan_check_read(from, n);
140 n = raw_copy_to_user(to, from, n);
141 }
142 return n;
143 }
144
145 static int copyin(void *to, const void __user *from, size_t n)
146 {
147 if (access_ok(VERIFY_READ, from, n)) {
148 kasan_check_write(to, n);
149 n = raw_copy_from_user(to, from, n);
150 }
151 return n;
152 }
153
154 static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes,
155 struct iov_iter *i)
156 {
157 size_t skip, copy, left, wanted;
158 const struct iovec *iov;
159 char __user *buf;
160 void *kaddr, *from;
161
162 if (unlikely(bytes > i->count))
163 bytes = i->count;
164
165 if (unlikely(!bytes))
166 return 0;
167
168 might_fault();
169 wanted = bytes;
170 iov = i->iov;
171 skip = i->iov_offset;
172 buf = iov->iov_base + skip;
173 copy = min(bytes, iov->iov_len - skip);
174
175 if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_writeable(buf, copy)) {
176 kaddr = kmap_atomic(page);
177 from = kaddr + offset;
178
179 /* first chunk, usually the only one */
180 left = copyout(buf, from, copy);
181 copy -= left;
182 skip += copy;
183 from += copy;
184 bytes -= copy;
185
186 while (unlikely(!left && bytes)) {
187 iov++;
188 buf = iov->iov_base;
189 copy = min(bytes, iov->iov_len);
190 left = copyout(buf, from, copy);
191 copy -= left;
192 skip = copy;
193 from += copy;
194 bytes -= copy;
195 }
196 if (likely(!bytes)) {
197 kunmap_atomic(kaddr);
198 goto done;
199 }
200 offset = from - kaddr;
201 buf += copy;
202 kunmap_atomic(kaddr);
203 copy = min(bytes, iov->iov_len - skip);
204 }
205 /* Too bad - revert to non-atomic kmap */
206
207 kaddr = kmap(page);
208 from = kaddr + offset;
209 left = copyout(buf, from, copy);
210 copy -= left;
211 skip += copy;
212 from += copy;
213 bytes -= copy;
214 while (unlikely(!left && bytes)) {
215 iov++;
216 buf = iov->iov_base;
217 copy = min(bytes, iov->iov_len);
218 left = copyout(buf, from, copy);
219 copy -= left;
220 skip = copy;
221 from += copy;
222 bytes -= copy;
223 }
224 kunmap(page);
225
226 done:
227 if (skip == iov->iov_len) {
228 iov++;
229 skip = 0;
230 }
231 i->count -= wanted - bytes;
232 i->nr_segs -= iov - i->iov;
233 i->iov = iov;
234 i->iov_offset = skip;
235 return wanted - bytes;
236 }
237
238 static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t bytes,
239 struct iov_iter *i)
240 {
241 size_t skip, copy, left, wanted;
242 const struct iovec *iov;
243 char __user *buf;
244 void *kaddr, *to;
245
246 if (unlikely(bytes > i->count))
247 bytes = i->count;
248
249 if (unlikely(!bytes))
250 return 0;
251
252 might_fault();
253 wanted = bytes;
254 iov = i->iov;
255 skip = i->iov_offset;
256 buf = iov->iov_base + skip;
257 copy = min(bytes, iov->iov_len - skip);
258
259 if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_readable(buf, copy)) {
260 kaddr = kmap_atomic(page);
261 to = kaddr + offset;
262
263 /* first chunk, usually the only one */
264 left = copyin(to, buf, copy);
265 copy -= left;
266 skip += copy;
267 to += copy;
268 bytes -= copy;
269
270 while (unlikely(!left && bytes)) {
271 iov++;
272 buf = iov->iov_base;
273 copy = min(bytes, iov->iov_len);
274 left = copyin(to, buf, copy);
275 copy -= left;
276 skip = copy;
277 to += copy;
278 bytes -= copy;
279 }
280 if (likely(!bytes)) {
281 kunmap_atomic(kaddr);
282 goto done;
283 }
284 offset = to - kaddr;
285 buf += copy;
286 kunmap_atomic(kaddr);
287 copy = min(bytes, iov->iov_len - skip);
288 }
289 /* Too bad - revert to non-atomic kmap */
290
291 kaddr = kmap(page);
292 to = kaddr + offset;
293 left = copyin(to, buf, copy);
294 copy -= left;
295 skip += copy;
296 to += copy;
297 bytes -= copy;
298 while (unlikely(!left && bytes)) {
299 iov++;
300 buf = iov->iov_base;
301 copy = min(bytes, iov->iov_len);
302 left = copyin(to, buf, copy);
303 copy -= left;
304 skip = copy;
305 to += copy;
306 bytes -= copy;
307 }
308 kunmap(page);
309
310 done:
311 if (skip == iov->iov_len) {
312 iov++;
313 skip = 0;
314 }
315 i->count -= wanted - bytes;
316 i->nr_segs -= iov - i->iov;
317 i->iov = iov;
318 i->iov_offset = skip;
319 return wanted - bytes;
320 }
321
322 #ifdef PIPE_PARANOIA
323 static bool sanity(const struct iov_iter *i)
324 {
325 struct pipe_inode_info *pipe = i->pipe;
326 int idx = i->idx;
327 int next = pipe->curbuf + pipe->nrbufs;
328 if (i->iov_offset) {
329 struct pipe_buffer *p;
330 if (unlikely(!pipe->nrbufs))
331 goto Bad; // pipe must be non-empty
332 if (unlikely(idx != ((next - 1) & (pipe->buffers - 1))))
333 goto Bad; // must be at the last buffer...
334
335 p = &pipe->bufs[idx];
336 if (unlikely(p->offset + p->len != i->iov_offset))
337 goto Bad; // ... at the end of segment
338 } else {
339 if (idx != (next & (pipe->buffers - 1)))
340 goto Bad; // must be right after the last buffer
341 }
342 return true;
343 Bad:
344 printk(KERN_ERR "idx = %d, offset = %zd\n", i->idx, i->iov_offset);
345 printk(KERN_ERR "curbuf = %d, nrbufs = %d, buffers = %d\n",
346 pipe->curbuf, pipe->nrbufs, pipe->buffers);
347 for (idx = 0; idx < pipe->buffers; idx++)
348 printk(KERN_ERR "[%p %p %d %d]\n",
349 pipe->bufs[idx].ops,
350 pipe->bufs[idx].page,
351 pipe->bufs[idx].offset,
352 pipe->bufs[idx].len);
353 WARN_ON(1);
354 return false;
355 }
356 #else
357 #define sanity(i) true
358 #endif
359
360 static inline int next_idx(int idx, struct pipe_inode_info *pipe)
361 {
362 return (idx + 1) & (pipe->buffers - 1);
363 }
364
365 static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes,
366 struct iov_iter *i)
367 {
368 struct pipe_inode_info *pipe = i->pipe;
369 struct pipe_buffer *buf;
370 size_t off;
371 int idx;
372
373 if (unlikely(bytes > i->count))
374 bytes = i->count;
375
376 if (unlikely(!bytes))
377 return 0;
378
379 if (!sanity(i))
380 return 0;
381
382 off = i->iov_offset;
383 idx = i->idx;
384 buf = &pipe->bufs[idx];
385 if (off) {
386 if (offset == off && buf->page == page) {
387 /* merge with the last one */
388 buf->len += bytes;
389 i->iov_offset += bytes;
390 goto out;
391 }
392 idx = next_idx(idx, pipe);
393 buf = &pipe->bufs[idx];
394 }
395 if (idx == pipe->curbuf && pipe->nrbufs)
396 return 0;
397 pipe->nrbufs++;
398 buf->ops = &page_cache_pipe_buf_ops;
399 get_page(buf->page = page);
400 buf->offset = offset;
401 buf->len = bytes;
402 i->iov_offset = offset + bytes;
403 i->idx = idx;
404 out:
405 i->count -= bytes;
406 return bytes;
407 }
408
409 /*
410 * Fault in one or more iovecs of the given iov_iter, to a maximum length of
411 * bytes. For each iovec, fault in each page that constitutes the iovec.
412 *
413 * Return 0 on success, or non-zero if the memory could not be accessed (i.e.
414 * because it is an invalid address).
415 */
416 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
417 {
418 size_t skip = i->iov_offset;
419 const struct iovec *iov;
420 int err;
421 struct iovec v;
422
423 if (!(i->type & (ITER_BVEC|ITER_KVEC))) {
424 iterate_iovec(i, bytes, v, iov, skip, ({
425 err = fault_in_pages_readable(v.iov_base, v.iov_len);
426 if (unlikely(err))
427 return err;
428 0;}))
429 }
430 return 0;
431 }
432 EXPORT_SYMBOL(iov_iter_fault_in_readable);
433
434 void iov_iter_init(struct iov_iter *i, unsigned int direction,
435 const struct iovec *iov, unsigned long nr_segs,
436 size_t count)
437 {
438 WARN_ON(direction & ~(READ | WRITE));
439 direction &= READ | WRITE;
440
441 /* It will get better. Eventually... */
442 if (uaccess_kernel()) {
443 i->type = ITER_KVEC | direction;
444 i->kvec = (struct kvec *)iov;
445 } else {
446 i->type = ITER_IOVEC | direction;
447 i->iov = iov;
448 }
449 i->nr_segs = nr_segs;
450 i->iov_offset = 0;
451 i->count = count;
452 }
453 EXPORT_SYMBOL(iov_iter_init);
454
455 static void memcpy_from_page(char *to, struct page *page, size_t offset, size_t len)
456 {
457 char *from = kmap_atomic(page);
458 memcpy(to, from + offset, len);
459 kunmap_atomic(from);
460 }
461
462 static void memcpy_to_page(struct page *page, size_t offset, const char *from, size_t len)
463 {
464 char *to = kmap_atomic(page);
465 memcpy(to + offset, from, len);
466 kunmap_atomic(to);
467 }
468
469 static void memzero_page(struct page *page, size_t offset, size_t len)
470 {
471 char *addr = kmap_atomic(page);
472 memset(addr + offset, 0, len);
473 kunmap_atomic(addr);
474 }
475
476 static inline bool allocated(struct pipe_buffer *buf)
477 {
478 return buf->ops == &default_pipe_buf_ops;
479 }
480
481 static inline void data_start(const struct iov_iter *i, int *idxp, size_t *offp)
482 {
483 size_t off = i->iov_offset;
484 int idx = i->idx;
485 if (off && (!allocated(&i->pipe->bufs[idx]) || off == PAGE_SIZE)) {
486 idx = next_idx(idx, i->pipe);
487 off = 0;
488 }
489 *idxp = idx;
490 *offp = off;
491 }
492
493 static size_t push_pipe(struct iov_iter *i, size_t size,
494 int *idxp, size_t *offp)
495 {
496 struct pipe_inode_info *pipe = i->pipe;
497 size_t off;
498 int idx;
499 ssize_t left;
500
501 if (unlikely(size > i->count))
502 size = i->count;
503 if (unlikely(!size))
504 return 0;
505
506 left = size;
507 data_start(i, &idx, &off);
508 *idxp = idx;
509 *offp = off;
510 if (off) {
511 left -= PAGE_SIZE - off;
512 if (left <= 0) {
513 pipe->bufs[idx].len += size;
514 return size;
515 }
516 pipe->bufs[idx].len = PAGE_SIZE;
517 idx = next_idx(idx, pipe);
518 }
519 while (idx != pipe->curbuf || !pipe->nrbufs) {
520 struct page *page = alloc_page(GFP_USER);
521 if (!page)
522 break;
523 pipe->nrbufs++;
524 pipe->bufs[idx].ops = &default_pipe_buf_ops;
525 pipe->bufs[idx].page = page;
526 pipe->bufs[idx].offset = 0;
527 if (left <= PAGE_SIZE) {
528 pipe->bufs[idx].len = left;
529 return size;
530 }
531 pipe->bufs[idx].len = PAGE_SIZE;
532 left -= PAGE_SIZE;
533 idx = next_idx(idx, pipe);
534 }
535 return size - left;
536 }
537
538 static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
539 struct iov_iter *i)
540 {
541 struct pipe_inode_info *pipe = i->pipe;
542 size_t n, off;
543 int idx;
544
545 if (!sanity(i))
546 return 0;
547
548 bytes = n = push_pipe(i, bytes, &idx, &off);
549 if (unlikely(!n))
550 return 0;
551 for ( ; n; idx = next_idx(idx, pipe), off = 0) {
552 size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
553 memcpy_to_page(pipe->bufs[idx].page, off, addr, chunk);
554 i->idx = idx;
555 i->iov_offset = off + chunk;
556 n -= chunk;
557 addr += chunk;
558 }
559 i->count -= bytes;
560 return bytes;
561 }
562
563 static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes,
564 __wsum *csum, struct iov_iter *i)
565 {
566 struct pipe_inode_info *pipe = i->pipe;
567 size_t n, r;
568 size_t off = 0;
569 __wsum sum = *csum, next;
570 int idx;
571
572 if (!sanity(i))
573 return 0;
574
575 bytes = n = push_pipe(i, bytes, &idx, &r);
576 if (unlikely(!n))
577 return 0;
578 for ( ; n; idx = next_idx(idx, pipe), r = 0) {
579 size_t chunk = min_t(size_t, n, PAGE_SIZE - r);
580 char *p = kmap_atomic(pipe->bufs[idx].page);
581 next = csum_partial_copy_nocheck(addr, p + r, chunk, 0);
582 sum = csum_block_add(sum, next, off);
583 kunmap_atomic(p);
584 i->idx = idx;
585 i->iov_offset = r + chunk;
586 n -= chunk;
587 off += chunk;
588 addr += chunk;
589 }
590 i->count -= bytes;
591 *csum = sum;
592 return bytes;
593 }
594
595 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
596 {
597 const char *from = addr;
598 if (unlikely(iov_iter_is_pipe(i)))
599 return copy_pipe_to_iter(addr, bytes, i);
600 if (iter_is_iovec(i))
601 might_fault();
602 iterate_and_advance(i, bytes, v,
603 copyout(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len),
604 memcpy_to_page(v.bv_page, v.bv_offset,
605 (from += v.bv_len) - v.bv_len, v.bv_len),
606 memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len)
607 )
608
609 return bytes;
610 }
611 EXPORT_SYMBOL(_copy_to_iter);
612
613 #ifdef CONFIG_ARCH_HAS_UACCESS_MCSAFE
614 static int copyout_mcsafe(void __user *to, const void *from, size_t n)
615 {
616 if (access_ok(VERIFY_WRITE, to, n)) {
617 kasan_check_read(from, n);
618 n = copy_to_user_mcsafe((__force void *) to, from, n);
619 }
620 return n;
621 }
622
623 static unsigned long memcpy_mcsafe_to_page(struct page *page, size_t offset,
624 const char *from, size_t len)
625 {
626 unsigned long ret;
627 char *to;
628
629 to = kmap_atomic(page);
630 ret = memcpy_mcsafe(to + offset, from, len);
631 kunmap_atomic(to);
632
633 return ret;
634 }
635
636 static size_t copy_pipe_to_iter_mcsafe(const void *addr, size_t bytes,
637 struct iov_iter *i)
638 {
639 struct pipe_inode_info *pipe = i->pipe;
640 size_t n, off, xfer = 0;
641 int idx;
642
643 if (!sanity(i))
644 return 0;
645
646 bytes = n = push_pipe(i, bytes, &idx, &off);
647 if (unlikely(!n))
648 return 0;
649 for ( ; n; idx = next_idx(idx, pipe), off = 0) {
650 size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
651 unsigned long rem;
652
653 rem = memcpy_mcsafe_to_page(pipe->bufs[idx].page, off, addr,
654 chunk);
655 i->idx = idx;
656 i->iov_offset = off + chunk - rem;
657 xfer += chunk - rem;
658 if (rem)
659 break;
660 n -= chunk;
661 addr += chunk;
662 }
663 i->count -= xfer;
664 return xfer;
665 }
666
667 /**
668 * _copy_to_iter_mcsafe - copy to user with source-read error exception handling
669 * @addr: source kernel address
670 * @bytes: total transfer length
671 * @iter: destination iterator
672 *
673 * The pmem driver arranges for filesystem-dax to use this facility via
674 * dax_copy_to_iter() for protecting read/write to persistent memory.
675 * Unless / until an architecture can guarantee identical performance
676 * between _copy_to_iter_mcsafe() and _copy_to_iter() it would be a
677 * performance regression to switch more users to the mcsafe version.
678 *
679 * Otherwise, the main differences between this and typical _copy_to_iter().
680 *
681 * * Typical tail/residue handling after a fault retries the copy
682 * byte-by-byte until the fault happens again. Re-triggering machine
683 * checks is potentially fatal so the implementation uses source
684 * alignment and poison alignment assumptions to avoid re-triggering
685 * hardware exceptions.
686 *
687 * * ITER_KVEC, ITER_PIPE, and ITER_BVEC can return short copies.
688 * Compare to copy_to_iter() where only ITER_IOVEC attempts might return
689 * a short copy.
690 *
691 * See MCSAFE_TEST for self-test.
692 */
693 size_t _copy_to_iter_mcsafe(const void *addr, size_t bytes, struct iov_iter *i)
694 {
695 const char *from = addr;
696 unsigned long rem, curr_addr, s_addr = (unsigned long) addr;
697
698 if (unlikely(iov_iter_is_pipe(i)))
699 return copy_pipe_to_iter_mcsafe(addr, bytes, i);
700 if (iter_is_iovec(i))
701 might_fault();
702 iterate_and_advance(i, bytes, v,
703 copyout_mcsafe(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len),
704 ({
705 rem = memcpy_mcsafe_to_page(v.bv_page, v.bv_offset,
706 (from += v.bv_len) - v.bv_len, v.bv_len);
707 if (rem) {
708 curr_addr = (unsigned long) from;
709 bytes = curr_addr - s_addr - rem;
710 return bytes;
711 }
712 }),
713 ({
714 rem = memcpy_mcsafe(v.iov_base, (from += v.iov_len) - v.iov_len,
715 v.iov_len);
716 if (rem) {
717 curr_addr = (unsigned long) from;
718 bytes = curr_addr - s_addr - rem;
719 return bytes;
720 }
721 })
722 )
723
724 return bytes;
725 }
726 EXPORT_SYMBOL_GPL(_copy_to_iter_mcsafe);
727 #endif /* CONFIG_ARCH_HAS_UACCESS_MCSAFE */
728
729 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
730 {
731 char *to = addr;
732 if (unlikely(iov_iter_is_pipe(i))) {
733 WARN_ON(1);
734 return 0;
735 }
736 if (iter_is_iovec(i))
737 might_fault();
738 iterate_and_advance(i, bytes, v,
739 copyin((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
740 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
741 v.bv_offset, v.bv_len),
742 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
743 )
744
745 return bytes;
746 }
747 EXPORT_SYMBOL(_copy_from_iter);
748
749 bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
750 {
751 char *to = addr;
752 if (unlikely(iov_iter_is_pipe(i))) {
753 WARN_ON(1);
754 return false;
755 }
756 if (unlikely(i->count < bytes))
757 return false;
758
759 if (iter_is_iovec(i))
760 might_fault();
761 iterate_all_kinds(i, bytes, v, ({
762 if (copyin((to += v.iov_len) - v.iov_len,
763 v.iov_base, v.iov_len))
764 return false;
765 0;}),
766 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
767 v.bv_offset, v.bv_len),
768 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
769 )
770
771 iov_iter_advance(i, bytes);
772 return true;
773 }
774 EXPORT_SYMBOL(_copy_from_iter_full);
775
776 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
777 {
778 char *to = addr;
779 if (unlikely(iov_iter_is_pipe(i))) {
780 WARN_ON(1);
781 return 0;
782 }
783 iterate_and_advance(i, bytes, v,
784 __copy_from_user_inatomic_nocache((to += v.iov_len) - v.iov_len,
785 v.iov_base, v.iov_len),
786 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
787 v.bv_offset, v.bv_len),
788 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
789 )
790
791 return bytes;
792 }
793 EXPORT_SYMBOL(_copy_from_iter_nocache);
794
795 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
796 /**
797 * _copy_from_iter_flushcache - write destination through cpu cache
798 * @addr: destination kernel address
799 * @bytes: total transfer length
800 * @iter: source iterator
801 *
802 * The pmem driver arranges for filesystem-dax to use this facility via
803 * dax_copy_from_iter() for ensuring that writes to persistent memory
804 * are flushed through the CPU cache. It is differentiated from
805 * _copy_from_iter_nocache() in that guarantees all data is flushed for
806 * all iterator types. The _copy_from_iter_nocache() only attempts to
807 * bypass the cache for the ITER_IOVEC case, and on some archs may use
808 * instructions that strand dirty-data in the cache.
809 */
810 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
811 {
812 char *to = addr;
813 if (unlikely(iov_iter_is_pipe(i))) {
814 WARN_ON(1);
815 return 0;
816 }
817 iterate_and_advance(i, bytes, v,
818 __copy_from_user_flushcache((to += v.iov_len) - v.iov_len,
819 v.iov_base, v.iov_len),
820 memcpy_page_flushcache((to += v.bv_len) - v.bv_len, v.bv_page,
821 v.bv_offset, v.bv_len),
822 memcpy_flushcache((to += v.iov_len) - v.iov_len, v.iov_base,
823 v.iov_len)
824 )
825
826 return bytes;
827 }
828 EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache);
829 #endif
830
831 bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
832 {
833 char *to = addr;
834 if (unlikely(iov_iter_is_pipe(i))) {
835 WARN_ON(1);
836 return false;
837 }
838 if (unlikely(i->count < bytes))
839 return false;
840 iterate_all_kinds(i, bytes, v, ({
841 if (__copy_from_user_inatomic_nocache((to += v.iov_len) - v.iov_len,
842 v.iov_base, v.iov_len))
843 return false;
844 0;}),
845 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
846 v.bv_offset, v.bv_len),
847 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
848 )
849
850 iov_iter_advance(i, bytes);
851 return true;
852 }
853 EXPORT_SYMBOL(_copy_from_iter_full_nocache);
854
855 static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
856 {
857 struct page *head = compound_head(page);
858 size_t v = n + offset + page_address(page) - page_address(head);
859
860 if (likely(n <= v && v <= (PAGE_SIZE << compound_order(head))))
861 return true;
862 WARN_ON(1);
863 return false;
864 }
865
866 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
867 struct iov_iter *i)
868 {
869 if (unlikely(!page_copy_sane(page, offset, bytes)))
870 return 0;
871 if (i->type & (ITER_BVEC|ITER_KVEC)) {
872 void *kaddr = kmap_atomic(page);
873 size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
874 kunmap_atomic(kaddr);
875 return wanted;
876 } else if (unlikely(iov_iter_is_discard(i)))
877 return bytes;
878 else if (likely(!iov_iter_is_pipe(i)))
879 return copy_page_to_iter_iovec(page, offset, bytes, i);
880 else
881 return copy_page_to_iter_pipe(page, offset, bytes, i);
882 }
883 EXPORT_SYMBOL(copy_page_to_iter);
884
885 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
886 struct iov_iter *i)
887 {
888 if (unlikely(!page_copy_sane(page, offset, bytes)))
889 return 0;
890 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
891 WARN_ON(1);
892 return 0;
893 }
894 if (i->type & (ITER_BVEC|ITER_KVEC)) {
895 void *kaddr = kmap_atomic(page);
896 size_t wanted = _copy_from_iter(kaddr + offset, bytes, i);
897 kunmap_atomic(kaddr);
898 return wanted;
899 } else
900 return copy_page_from_iter_iovec(page, offset, bytes, i);
901 }
902 EXPORT_SYMBOL(copy_page_from_iter);
903
904 static size_t pipe_zero(size_t bytes, struct iov_iter *i)
905 {
906 struct pipe_inode_info *pipe = i->pipe;
907 size_t n, off;
908 int idx;
909
910 if (!sanity(i))
911 return 0;
912
913 bytes = n = push_pipe(i, bytes, &idx, &off);
914 if (unlikely(!n))
915 return 0;
916
917 for ( ; n; idx = next_idx(idx, pipe), off = 0) {
918 size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
919 memzero_page(pipe->bufs[idx].page, off, chunk);
920 i->idx = idx;
921 i->iov_offset = off + chunk;
922 n -= chunk;
923 }
924 i->count -= bytes;
925 return bytes;
926 }
927
928 size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
929 {
930 if (unlikely(iov_iter_is_pipe(i)))
931 return pipe_zero(bytes, i);
932 iterate_and_advance(i, bytes, v,
933 clear_user(v.iov_base, v.iov_len),
934 memzero_page(v.bv_page, v.bv_offset, v.bv_len),
935 memset(v.iov_base, 0, v.iov_len)
936 )
937
938 return bytes;
939 }
940 EXPORT_SYMBOL(iov_iter_zero);
941
942 size_t iov_iter_copy_from_user_atomic(struct page *page,
943 struct iov_iter *i, unsigned long offset, size_t bytes)
944 {
945 char *kaddr = kmap_atomic(page), *p = kaddr + offset;
946 if (unlikely(!page_copy_sane(page, offset, bytes))) {
947 kunmap_atomic(kaddr);
948 return 0;
949 }
950 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
951 kunmap_atomic(kaddr);
952 WARN_ON(1);
953 return 0;
954 }
955 iterate_all_kinds(i, bytes, v,
956 copyin((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
957 memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page,
958 v.bv_offset, v.bv_len),
959 memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
960 )
961 kunmap_atomic(kaddr);
962 return bytes;
963 }
964 EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
965
966 static inline void pipe_truncate(struct iov_iter *i)
967 {
968 struct pipe_inode_info *pipe = i->pipe;
969 if (pipe->nrbufs) {
970 size_t off = i->iov_offset;
971 int idx = i->idx;
972 int nrbufs = (idx - pipe->curbuf) & (pipe->buffers - 1);
973 if (off) {
974 pipe->bufs[idx].len = off - pipe->bufs[idx].offset;
975 idx = next_idx(idx, pipe);
976 nrbufs++;
977 }
978 while (pipe->nrbufs > nrbufs) {
979 pipe_buf_release(pipe, &pipe->bufs[idx]);
980 idx = next_idx(idx, pipe);
981 pipe->nrbufs--;
982 }
983 }
984 }
985
986 static void pipe_advance(struct iov_iter *i, size_t size)
987 {
988 struct pipe_inode_info *pipe = i->pipe;
989 if (unlikely(i->count < size))
990 size = i->count;
991 if (size) {
992 struct pipe_buffer *buf;
993 size_t off = i->iov_offset, left = size;
994 int idx = i->idx;
995 if (off) /* make it relative to the beginning of buffer */
996 left += off - pipe->bufs[idx].offset;
997 while (1) {
998 buf = &pipe->bufs[idx];
999 if (left <= buf->len)
1000 break;
1001 left -= buf->len;
1002 idx = next_idx(idx, pipe);
1003 }
1004 i->idx = idx;
1005 i->iov_offset = buf->offset + left;
1006 }
1007 i->count -= size;
1008 /* ... and discard everything past that point */
1009 pipe_truncate(i);
1010 }
1011
1012 void iov_iter_advance(struct iov_iter *i, size_t size)
1013 {
1014 if (unlikely(iov_iter_is_pipe(i))) {
1015 pipe_advance(i, size);
1016 return;
1017 }
1018 if (unlikely(iov_iter_is_discard(i))) {
1019 i->count -= size;
1020 return;
1021 }
1022 iterate_and_advance(i, size, v, 0, 0, 0)
1023 }
1024 EXPORT_SYMBOL(iov_iter_advance);
1025
1026 void iov_iter_revert(struct iov_iter *i, size_t unroll)
1027 {
1028 if (!unroll)
1029 return;
1030 if (WARN_ON(unroll > MAX_RW_COUNT))
1031 return;
1032 i->count += unroll;
1033 if (unlikely(iov_iter_is_pipe(i))) {
1034 struct pipe_inode_info *pipe = i->pipe;
1035 int idx = i->idx;
1036 size_t off = i->iov_offset;
1037 while (1) {
1038 size_t n = off - pipe->bufs[idx].offset;
1039 if (unroll < n) {
1040 off -= unroll;
1041 break;
1042 }
1043 unroll -= n;
1044 if (!unroll && idx == i->start_idx) {
1045 off = 0;
1046 break;
1047 }
1048 if (!idx--)
1049 idx = pipe->buffers - 1;
1050 off = pipe->bufs[idx].offset + pipe->bufs[idx].len;
1051 }
1052 i->iov_offset = off;
1053 i->idx = idx;
1054 pipe_truncate(i);
1055 return;
1056 }
1057 if (unlikely(iov_iter_is_discard(i)))
1058 return;
1059 if (unroll <= i->iov_offset) {
1060 i->iov_offset -= unroll;
1061 return;
1062 }
1063 unroll -= i->iov_offset;
1064 if (iov_iter_is_bvec(i)) {
1065 const struct bio_vec *bvec = i->bvec;
1066 while (1) {
1067 size_t n = (--bvec)->bv_len;
1068 i->nr_segs++;
1069 if (unroll <= n) {
1070 i->bvec = bvec;
1071 i->iov_offset = n - unroll;
1072 return;
1073 }
1074 unroll -= n;
1075 }
1076 } else { /* same logics for iovec and kvec */
1077 const struct iovec *iov = i->iov;
1078 while (1) {
1079 size_t n = (--iov)->iov_len;
1080 i->nr_segs++;
1081 if (unroll <= n) {
1082 i->iov = iov;
1083 i->iov_offset = n - unroll;
1084 return;
1085 }
1086 unroll -= n;
1087 }
1088 }
1089 }
1090 EXPORT_SYMBOL(iov_iter_revert);
1091
1092 /*
1093 * Return the count of just the current iov_iter segment.
1094 */
1095 size_t iov_iter_single_seg_count(const struct iov_iter *i)
1096 {
1097 if (unlikely(iov_iter_is_pipe(i)))
1098 return i->count; // it is a silly place, anyway
1099 if (i->nr_segs == 1)
1100 return i->count;
1101 if (unlikely(iov_iter_is_discard(i)))
1102 return i->count;
1103 else if (iov_iter_is_bvec(i))
1104 return min(i->count, i->bvec->bv_len - i->iov_offset);
1105 else
1106 return min(i->count, i->iov->iov_len - i->iov_offset);
1107 }
1108 EXPORT_SYMBOL(iov_iter_single_seg_count);
1109
1110 void iov_iter_kvec(struct iov_iter *i, unsigned int direction,
1111 const struct kvec *kvec, unsigned long nr_segs,
1112 size_t count)
1113 {
1114 WARN_ON(direction & ~(READ | WRITE));
1115 i->type = ITER_KVEC | (direction & (READ | WRITE));
1116 i->kvec = kvec;
1117 i->nr_segs = nr_segs;
1118 i->iov_offset = 0;
1119 i->count = count;
1120 }
1121 EXPORT_SYMBOL(iov_iter_kvec);
1122
1123 void iov_iter_bvec(struct iov_iter *i, unsigned int direction,
1124 const struct bio_vec *bvec, unsigned long nr_segs,
1125 size_t count)
1126 {
1127 WARN_ON(direction & ~(READ | WRITE));
1128 i->type = ITER_BVEC | (direction & (READ | WRITE));
1129 i->bvec = bvec;
1130 i->nr_segs = nr_segs;
1131 i->iov_offset = 0;
1132 i->count = count;
1133 }
1134 EXPORT_SYMBOL(iov_iter_bvec);
1135
1136 void iov_iter_pipe(struct iov_iter *i, unsigned int direction,
1137 struct pipe_inode_info *pipe,
1138 size_t count)
1139 {
1140 BUG_ON(direction != READ);
1141 WARN_ON(pipe->nrbufs == pipe->buffers);
1142 i->type = ITER_PIPE | READ;
1143 i->pipe = pipe;
1144 i->idx = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
1145 i->iov_offset = 0;
1146 i->count = count;
1147 i->start_idx = i->idx;
1148 }
1149 EXPORT_SYMBOL(iov_iter_pipe);
1150
1151 /**
1152 * iov_iter_discard - Initialise an I/O iterator that discards data
1153 * @i: The iterator to initialise.
1154 * @direction: The direction of the transfer.
1155 * @count: The size of the I/O buffer in bytes.
1156 *
1157 * Set up an I/O iterator that just discards everything that's written to it.
1158 * It's only available as a READ iterator.
1159 */
1160 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count)
1161 {
1162 BUG_ON(direction != READ);
1163 i->type = ITER_DISCARD | READ;
1164 i->count = count;
1165 i->iov_offset = 0;
1166 }
1167 EXPORT_SYMBOL(iov_iter_discard);
1168
1169 unsigned long iov_iter_alignment(const struct iov_iter *i)
1170 {
1171 unsigned long res = 0;
1172 size_t size = i->count;
1173
1174 if (unlikely(iov_iter_is_pipe(i))) {
1175 if (size && i->iov_offset && allocated(&i->pipe->bufs[i->idx]))
1176 return size | i->iov_offset;
1177 return size;
1178 }
1179 iterate_all_kinds(i, size, v,
1180 (res |= (unsigned long)v.iov_base | v.iov_len, 0),
1181 res |= v.bv_offset | v.bv_len,
1182 res |= (unsigned long)v.iov_base | v.iov_len
1183 )
1184 return res;
1185 }
1186 EXPORT_SYMBOL(iov_iter_alignment);
1187
1188 unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
1189 {
1190 unsigned long res = 0;
1191 size_t size = i->count;
1192
1193 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
1194 WARN_ON(1);
1195 return ~0U;
1196 }
1197
1198 iterate_all_kinds(i, size, v,
1199 (res |= (!res ? 0 : (unsigned long)v.iov_base) |
1200 (size != v.iov_len ? size : 0), 0),
1201 (res |= (!res ? 0 : (unsigned long)v.bv_offset) |
1202 (size != v.bv_len ? size : 0)),
1203 (res |= (!res ? 0 : (unsigned long)v.iov_base) |
1204 (size != v.iov_len ? size : 0))
1205 );
1206 return res;
1207 }
1208 EXPORT_SYMBOL(iov_iter_gap_alignment);
1209
1210 static inline ssize_t __pipe_get_pages(struct iov_iter *i,
1211 size_t maxsize,
1212 struct page **pages,
1213 int idx,
1214 size_t *start)
1215 {
1216 struct pipe_inode_info *pipe = i->pipe;
1217 ssize_t n = push_pipe(i, maxsize, &idx, start);
1218 if (!n)
1219 return -EFAULT;
1220
1221 maxsize = n;
1222 n += *start;
1223 while (n > 0) {
1224 get_page(*pages++ = pipe->bufs[idx].page);
1225 idx = next_idx(idx, pipe);
1226 n -= PAGE_SIZE;
1227 }
1228
1229 return maxsize;
1230 }
1231
1232 static ssize_t pipe_get_pages(struct iov_iter *i,
1233 struct page **pages, size_t maxsize, unsigned maxpages,
1234 size_t *start)
1235 {
1236 unsigned npages;
1237 size_t capacity;
1238 int idx;
1239
1240 if (!maxsize)
1241 return 0;
1242
1243 if (!sanity(i))
1244 return -EFAULT;
1245
1246 data_start(i, &idx, start);
1247 /* some of this one + all after this one */
1248 npages = ((i->pipe->curbuf - idx - 1) & (i->pipe->buffers - 1)) + 1;
1249 capacity = min(npages,maxpages) * PAGE_SIZE - *start;
1250
1251 return __pipe_get_pages(i, min(maxsize, capacity), pages, idx, start);
1252 }
1253
1254 ssize_t iov_iter_get_pages(struct iov_iter *i,
1255 struct page **pages, size_t maxsize, unsigned maxpages,
1256 size_t *start)
1257 {
1258 if (maxsize > i->count)
1259 maxsize = i->count;
1260
1261 if (unlikely(iov_iter_is_pipe(i)))
1262 return pipe_get_pages(i, pages, maxsize, maxpages, start);
1263 if (unlikely(iov_iter_is_discard(i)))
1264 return -EFAULT;
1265
1266 iterate_all_kinds(i, maxsize, v, ({
1267 unsigned long addr = (unsigned long)v.iov_base;
1268 size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
1269 int n;
1270 int res;
1271
1272 if (len > maxpages * PAGE_SIZE)
1273 len = maxpages * PAGE_SIZE;
1274 addr &= ~(PAGE_SIZE - 1);
1275 n = DIV_ROUND_UP(len, PAGE_SIZE);
1276 res = get_user_pages_fast(addr, n, iov_iter_rw(i) != WRITE, pages);
1277 if (unlikely(res < 0))
1278 return res;
1279 return (res == n ? len : res * PAGE_SIZE) - *start;
1280 0;}),({
1281 /* can't be more than PAGE_SIZE */
1282 *start = v.bv_offset;
1283 get_page(*pages = v.bv_page);
1284 return v.bv_len;
1285 }),({
1286 return -EFAULT;
1287 })
1288 )
1289 return 0;
1290 }
1291 EXPORT_SYMBOL(iov_iter_get_pages);
1292
1293 static struct page **get_pages_array(size_t n)
1294 {
1295 return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL);
1296 }
1297
1298 static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
1299 struct page ***pages, size_t maxsize,
1300 size_t *start)
1301 {
1302 struct page **p;
1303 ssize_t n;
1304 int idx;
1305 int npages;
1306
1307 if (!maxsize)
1308 return 0;
1309
1310 if (!sanity(i))
1311 return -EFAULT;
1312
1313 data_start(i, &idx, start);
1314 /* some of this one + all after this one */
1315 npages = ((i->pipe->curbuf - idx - 1) & (i->pipe->buffers - 1)) + 1;
1316 n = npages * PAGE_SIZE - *start;
1317 if (maxsize > n)
1318 maxsize = n;
1319 else
1320 npages = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
1321 p = get_pages_array(npages);
1322 if (!p)
1323 return -ENOMEM;
1324 n = __pipe_get_pages(i, maxsize, p, idx, start);
1325 if (n > 0)
1326 *pages = p;
1327 else
1328 kvfree(p);
1329 return n;
1330 }
1331
1332 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
1333 struct page ***pages, size_t maxsize,
1334 size_t *start)
1335 {
1336 struct page **p;
1337
1338 if (maxsize > i->count)
1339 maxsize = i->count;
1340
1341 if (unlikely(iov_iter_is_pipe(i)))
1342 return pipe_get_pages_alloc(i, pages, maxsize, start);
1343 if (unlikely(iov_iter_is_discard(i)))
1344 return -EFAULT;
1345
1346 iterate_all_kinds(i, maxsize, v, ({
1347 unsigned long addr = (unsigned long)v.iov_base;
1348 size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
1349 int n;
1350 int res;
1351
1352 addr &= ~(PAGE_SIZE - 1);
1353 n = DIV_ROUND_UP(len, PAGE_SIZE);
1354 p = get_pages_array(n);
1355 if (!p)
1356 return -ENOMEM;
1357 res = get_user_pages_fast(addr, n, iov_iter_rw(i) != WRITE, p);
1358 if (unlikely(res < 0)) {
1359 kvfree(p);
1360 return res;
1361 }
1362 *pages = p;
1363 return (res == n ? len : res * PAGE_SIZE) - *start;
1364 0;}),({
1365 /* can't be more than PAGE_SIZE */
1366 *start = v.bv_offset;
1367 *pages = p = get_pages_array(1);
1368 if (!p)
1369 return -ENOMEM;
1370 get_page(*p = v.bv_page);
1371 return v.bv_len;
1372 }),({
1373 return -EFAULT;
1374 })
1375 )
1376 return 0;
1377 }
1378 EXPORT_SYMBOL(iov_iter_get_pages_alloc);
1379
1380 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
1381 struct iov_iter *i)
1382 {
1383 char *to = addr;
1384 __wsum sum, next;
1385 size_t off = 0;
1386 sum = *csum;
1387 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
1388 WARN_ON(1);
1389 return 0;
1390 }
1391 iterate_and_advance(i, bytes, v, ({
1392 int err = 0;
1393 next = csum_and_copy_from_user(v.iov_base,
1394 (to += v.iov_len) - v.iov_len,
1395 v.iov_len, 0, &err);
1396 if (!err) {
1397 sum = csum_block_add(sum, next, off);
1398 off += v.iov_len;
1399 }
1400 err ? v.iov_len : 0;
1401 }), ({
1402 char *p = kmap_atomic(v.bv_page);
1403 next = csum_partial_copy_nocheck(p + v.bv_offset,
1404 (to += v.bv_len) - v.bv_len,
1405 v.bv_len, 0);
1406 kunmap_atomic(p);
1407 sum = csum_block_add(sum, next, off);
1408 off += v.bv_len;
1409 }),({
1410 next = csum_partial_copy_nocheck(v.iov_base,
1411 (to += v.iov_len) - v.iov_len,
1412 v.iov_len, 0);
1413 sum = csum_block_add(sum, next, off);
1414 off += v.iov_len;
1415 })
1416 )
1417 *csum = sum;
1418 return bytes;
1419 }
1420 EXPORT_SYMBOL(csum_and_copy_from_iter);
1421
1422 bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum,
1423 struct iov_iter *i)
1424 {
1425 char *to = addr;
1426 __wsum sum, next;
1427 size_t off = 0;
1428 sum = *csum;
1429 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
1430 WARN_ON(1);
1431 return false;
1432 }
1433 if (unlikely(i->count < bytes))
1434 return false;
1435 iterate_all_kinds(i, bytes, v, ({
1436 int err = 0;
1437 next = csum_and_copy_from_user(v.iov_base,
1438 (to += v.iov_len) - v.iov_len,
1439 v.iov_len, 0, &err);
1440 if (err)
1441 return false;
1442 sum = csum_block_add(sum, next, off);
1443 off += v.iov_len;
1444 0;
1445 }), ({
1446 char *p = kmap_atomic(v.bv_page);
1447 next = csum_partial_copy_nocheck(p + v.bv_offset,
1448 (to += v.bv_len) - v.bv_len,
1449 v.bv_len, 0);
1450 kunmap_atomic(p);
1451 sum = csum_block_add(sum, next, off);
1452 off += v.bv_len;
1453 }),({
1454 next = csum_partial_copy_nocheck(v.iov_base,
1455 (to += v.iov_len) - v.iov_len,
1456 v.iov_len, 0);
1457 sum = csum_block_add(sum, next, off);
1458 off += v.iov_len;
1459 })
1460 )
1461 *csum = sum;
1462 iov_iter_advance(i, bytes);
1463 return true;
1464 }
1465 EXPORT_SYMBOL(csum_and_copy_from_iter_full);
1466
1467 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum,
1468 struct iov_iter *i)
1469 {
1470 const char *from = addr;
1471 __wsum sum, next;
1472 size_t off = 0;
1473
1474 if (unlikely(iov_iter_is_pipe(i)))
1475 return csum_and_copy_to_pipe_iter(addr, bytes, csum, i);
1476
1477 sum = *csum;
1478 if (unlikely(iov_iter_is_discard(i))) {
1479 WARN_ON(1); /* for now */
1480 return 0;
1481 }
1482 iterate_and_advance(i, bytes, v, ({
1483 int err = 0;
1484 next = csum_and_copy_to_user((from += v.iov_len) - v.iov_len,
1485 v.iov_base,
1486 v.iov_len, 0, &err);
1487 if (!err) {
1488 sum = csum_block_add(sum, next, off);
1489 off += v.iov_len;
1490 }
1491 err ? v.iov_len : 0;
1492 }), ({
1493 char *p = kmap_atomic(v.bv_page);
1494 next = csum_partial_copy_nocheck((from += v.bv_len) - v.bv_len,
1495 p + v.bv_offset,
1496 v.bv_len, 0);
1497 kunmap_atomic(p);
1498 sum = csum_block_add(sum, next, off);
1499 off += v.bv_len;
1500 }),({
1501 next = csum_partial_copy_nocheck((from += v.iov_len) - v.iov_len,
1502 v.iov_base,
1503 v.iov_len, 0);
1504 sum = csum_block_add(sum, next, off);
1505 off += v.iov_len;
1506 })
1507 )
1508 *csum = sum;
1509 return bytes;
1510 }
1511 EXPORT_SYMBOL(csum_and_copy_to_iter);
1512
1513 int iov_iter_npages(const struct iov_iter *i, int maxpages)
1514 {
1515 size_t size = i->count;
1516 int npages = 0;
1517
1518 if (!size)
1519 return 0;
1520 if (unlikely(iov_iter_is_discard(i)))
1521 return 0;
1522
1523 if (unlikely(iov_iter_is_pipe(i))) {
1524 struct pipe_inode_info *pipe = i->pipe;
1525 size_t off;
1526 int idx;
1527
1528 if (!sanity(i))
1529 return 0;
1530
1531 data_start(i, &idx, &off);
1532 /* some of this one + all after this one */
1533 npages = ((pipe->curbuf - idx - 1) & (pipe->buffers - 1)) + 1;
1534 if (npages >= maxpages)
1535 return maxpages;
1536 } else iterate_all_kinds(i, size, v, ({
1537 unsigned long p = (unsigned long)v.iov_base;
1538 npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
1539 - p / PAGE_SIZE;
1540 if (npages >= maxpages)
1541 return maxpages;
1542 0;}),({
1543 npages++;
1544 if (npages >= maxpages)
1545 return maxpages;
1546 }),({
1547 unsigned long p = (unsigned long)v.iov_base;
1548 npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
1549 - p / PAGE_SIZE;
1550 if (npages >= maxpages)
1551 return maxpages;
1552 })
1553 )
1554 return npages;
1555 }
1556 EXPORT_SYMBOL(iov_iter_npages);
1557
1558 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
1559 {
1560 *new = *old;
1561 if (unlikely(iov_iter_is_pipe(new))) {
1562 WARN_ON(1);
1563 return NULL;
1564 }
1565 if (unlikely(iov_iter_is_discard(new)))
1566 return NULL;
1567 if (iov_iter_is_bvec(new))
1568 return new->bvec = kmemdup(new->bvec,
1569 new->nr_segs * sizeof(struct bio_vec),
1570 flags);
1571 else
1572 /* iovec and kvec have identical layout */
1573 return new->iov = kmemdup(new->iov,
1574 new->nr_segs * sizeof(struct iovec),
1575 flags);
1576 }
1577 EXPORT_SYMBOL(dup_iter);
1578
1579 /**
1580 * import_iovec() - Copy an array of &struct iovec from userspace
1581 * into the kernel, check that it is valid, and initialize a new
1582 * &struct iov_iter iterator to access it.
1583 *
1584 * @type: One of %READ or %WRITE.
1585 * @uvector: Pointer to the userspace array.
1586 * @nr_segs: Number of elements in userspace array.
1587 * @fast_segs: Number of elements in @iov.
1588 * @iov: (input and output parameter) Pointer to pointer to (usually small
1589 * on-stack) kernel array.
1590 * @i: Pointer to iterator that will be initialized on success.
1591 *
1592 * If the array pointed to by *@iov is large enough to hold all @nr_segs,
1593 * then this function places %NULL in *@iov on return. Otherwise, a new
1594 * array will be allocated and the result placed in *@iov. This means that
1595 * the caller may call kfree() on *@iov regardless of whether the small
1596 * on-stack array was used or not (and regardless of whether this function
1597 * returns an error or not).
1598 *
1599 * Return: 0 on success or negative error code on error.
1600 */
1601 int import_iovec(int type, const struct iovec __user * uvector,
1602 unsigned nr_segs, unsigned fast_segs,
1603 struct iovec **iov, struct iov_iter *i)
1604 {
1605 ssize_t n;
1606 struct iovec *p;
1607 n = rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
1608 *iov, &p);
1609 if (n < 0) {
1610 if (p != *iov)
1611 kfree(p);
1612 *iov = NULL;
1613 return n;
1614 }
1615 iov_iter_init(i, type, p, nr_segs, n);
1616 *iov = p == *iov ? NULL : p;
1617 return 0;
1618 }
1619 EXPORT_SYMBOL(import_iovec);
1620
1621 #ifdef CONFIG_COMPAT
1622 #include <linux/compat.h>
1623
1624 int compat_import_iovec(int type, const struct compat_iovec __user * uvector,
1625 unsigned nr_segs, unsigned fast_segs,
1626 struct iovec **iov, struct iov_iter *i)
1627 {
1628 ssize_t n;
1629 struct iovec *p;
1630 n = compat_rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
1631 *iov, &p);
1632 if (n < 0) {
1633 if (p != *iov)
1634 kfree(p);
1635 *iov = NULL;
1636 return n;
1637 }
1638 iov_iter_init(i, type, p, nr_segs, n);
1639 *iov = p == *iov ? NULL : p;
1640 return 0;
1641 }
1642 #endif
1643
1644 int import_single_range(int rw, void __user *buf, size_t len,
1645 struct iovec *iov, struct iov_iter *i)
1646 {
1647 if (len > MAX_RW_COUNT)
1648 len = MAX_RW_COUNT;
1649 if (unlikely(!access_ok(!rw, buf, len)))
1650 return -EFAULT;
1651
1652 iov->iov_base = buf;
1653 iov->iov_len = len;
1654 iov_iter_init(i, rw, iov, 1, len);
1655 return 0;
1656 }
1657 EXPORT_SYMBOL(import_single_range);
1658
1659 int iov_iter_for_each_range(struct iov_iter *i, size_t bytes,
1660 int (*f)(struct kvec *vec, void *context),
1661 void *context)
1662 {
1663 struct kvec w;
1664 int err = -EINVAL;
1665 if (!bytes)
1666 return 0;
1667
1668 iterate_all_kinds(i, bytes, v, -EINVAL, ({
1669 w.iov_base = kmap(v.bv_page) + v.bv_offset;
1670 w.iov_len = v.bv_len;
1671 err = f(&w, context);
1672 kunmap(v.bv_page);
1673 err;}), ({
1674 w = v;
1675 err = f(&w, context);})
1676 )
1677 return err;
1678 }
1679 EXPORT_SYMBOL(iov_iter_for_each_range);
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