Merge tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc
[linux-2.6-microblaze.git] / lib / iov_iter.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/export.h>
3 #include <linux/bvec.h>
4 #include <linux/uio.h>
5 #include <linux/pagemap.h>
6 #include <linux/slab.h>
7 #include <linux/vmalloc.h>
8 #include <linux/splice.h>
9 #include <net/checksum.h>
10 #include <linux/scatterlist.h>
11
12 #define PIPE_PARANOIA /* for now */
13
14 #define iterate_iovec(i, n, __v, __p, skip, STEP) {     \
15         size_t left;                                    \
16         size_t wanted = n;                              \
17         __p = i->iov;                                   \
18         __v.iov_len = min(n, __p->iov_len - skip);      \
19         if (likely(__v.iov_len)) {                      \
20                 __v.iov_base = __p->iov_base + skip;    \
21                 left = (STEP);                          \
22                 __v.iov_len -= left;                    \
23                 skip += __v.iov_len;                    \
24                 n -= __v.iov_len;                       \
25         } else {                                        \
26                 left = 0;                               \
27         }                                               \
28         while (unlikely(!left && n)) {                  \
29                 __p++;                                  \
30                 __v.iov_len = min(n, __p->iov_len);     \
31                 if (unlikely(!__v.iov_len))             \
32                         continue;                       \
33                 __v.iov_base = __p->iov_base;           \
34                 left = (STEP);                          \
35                 __v.iov_len -= left;                    \
36                 skip = __v.iov_len;                     \
37                 n -= __v.iov_len;                       \
38         }                                               \
39         n = wanted - n;                                 \
40 }
41
42 #define iterate_kvec(i, n, __v, __p, skip, STEP) {      \
43         size_t wanted = n;                              \
44         __p = i->kvec;                                  \
45         __v.iov_len = min(n, __p->iov_len - skip);      \
46         if (likely(__v.iov_len)) {                      \
47                 __v.iov_base = __p->iov_base + skip;    \
48                 (void)(STEP);                           \
49                 skip += __v.iov_len;                    \
50                 n -= __v.iov_len;                       \
51         }                                               \
52         while (unlikely(n)) {                           \
53                 __p++;                                  \
54                 __v.iov_len = min(n, __p->iov_len);     \
55                 if (unlikely(!__v.iov_len))             \
56                         continue;                       \
57                 __v.iov_base = __p->iov_base;           \
58                 (void)(STEP);                           \
59                 skip = __v.iov_len;                     \
60                 n -= __v.iov_len;                       \
61         }                                               \
62         n = wanted;                                     \
63 }
64
65 #define iterate_bvec(i, n, __v, __bi, skip, STEP) {     \
66         struct bvec_iter __start;                       \
67         __start.bi_size = n;                            \
68         __start.bi_bvec_done = skip;                    \
69         __start.bi_idx = 0;                             \
70         for_each_bvec(__v, i->bvec, __bi, __start) {    \
71                 if (!__v.bv_len)                        \
72                         continue;                       \
73                 (void)(STEP);                           \
74         }                                               \
75 }
76
77 #define iterate_all_kinds(i, n, v, I, B, K) {                   \
78         if (likely(n)) {                                        \
79                 size_t skip = i->iov_offset;                    \
80                 if (unlikely(i->type & ITER_BVEC)) {            \
81                         struct bio_vec v;                       \
82                         struct bvec_iter __bi;                  \
83                         iterate_bvec(i, n, v, __bi, skip, (B))  \
84                 } else if (unlikely(i->type & ITER_KVEC)) {     \
85                         const struct kvec *kvec;                \
86                         struct kvec v;                          \
87                         iterate_kvec(i, n, v, kvec, skip, (K))  \
88                 } else if (unlikely(i->type & ITER_DISCARD)) {  \
89                 } else {                                        \
90                         const struct iovec *iov;                \
91                         struct iovec v;                         \
92                         iterate_iovec(i, n, v, iov, skip, (I))  \
93                 }                                               \
94         }                                                       \
95 }
96
97 #define iterate_and_advance(i, n, v, I, B, K) {                 \
98         if (unlikely(i->count < n))                             \
99                 n = i->count;                                   \
100         if (i->count) {                                         \
101                 size_t skip = i->iov_offset;                    \
102                 if (unlikely(i->type & ITER_BVEC)) {            \
103                         const struct bio_vec *bvec = i->bvec;   \
104                         struct bio_vec v;                       \
105                         struct bvec_iter __bi;                  \
106                         iterate_bvec(i, n, v, __bi, skip, (B))  \
107                         i->bvec = __bvec_iter_bvec(i->bvec, __bi);      \
108                         i->nr_segs -= i->bvec - bvec;           \
109                         skip = __bi.bi_bvec_done;               \
110                 } else if (unlikely(i->type & ITER_KVEC)) {     \
111                         const struct kvec *kvec;                \
112                         struct kvec v;                          \
113                         iterate_kvec(i, n, v, kvec, skip, (K))  \
114                         if (skip == kvec->iov_len) {            \
115                                 kvec++;                         \
116                                 skip = 0;                       \
117                         }                                       \
118                         i->nr_segs -= kvec - i->kvec;           \
119                         i->kvec = kvec;                         \
120                 } else if (unlikely(i->type & ITER_DISCARD)) {  \
121                         skip += n;                              \
122                 } else {                                        \
123                         const struct iovec *iov;                \
124                         struct iovec v;                         \
125                         iterate_iovec(i, n, v, iov, skip, (I))  \
126                         if (skip == iov->iov_len) {             \
127                                 iov++;                          \
128                                 skip = 0;                       \
129                         }                                       \
130                         i->nr_segs -= iov - i->iov;             \
131                         i->iov = iov;                           \
132                 }                                               \
133                 i->count -= n;                                  \
134                 i->iov_offset = skip;                           \
135         }                                                       \
136 }
137
138 static int copyout(void __user *to, const void *from, size_t n)
139 {
140         if (access_ok(to, n)) {
141                 kasan_check_read(from, n);
142                 n = raw_copy_to_user(to, from, n);
143         }
144         return n;
145 }
146
147 static int copyin(void *to, const void __user *from, size_t n)
148 {
149         if (access_ok(from, n)) {
150                 kasan_check_write(to, n);
151                 n = raw_copy_from_user(to, from, n);
152         }
153         return n;
154 }
155
156 static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes,
157                          struct iov_iter *i)
158 {
159         size_t skip, copy, left, wanted;
160         const struct iovec *iov;
161         char __user *buf;
162         void *kaddr, *from;
163
164         if (unlikely(bytes > i->count))
165                 bytes = i->count;
166
167         if (unlikely(!bytes))
168                 return 0;
169
170         might_fault();
171         wanted = bytes;
172         iov = i->iov;
173         skip = i->iov_offset;
174         buf = iov->iov_base + skip;
175         copy = min(bytes, iov->iov_len - skip);
176
177         if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_writeable(buf, copy)) {
178                 kaddr = kmap_atomic(page);
179                 from = kaddr + offset;
180
181                 /* first chunk, usually the only one */
182                 left = copyout(buf, from, copy);
183                 copy -= left;
184                 skip += copy;
185                 from += copy;
186                 bytes -= copy;
187
188                 while (unlikely(!left && bytes)) {
189                         iov++;
190                         buf = iov->iov_base;
191                         copy = min(bytes, iov->iov_len);
192                         left = copyout(buf, from, copy);
193                         copy -= left;
194                         skip = copy;
195                         from += copy;
196                         bytes -= copy;
197                 }
198                 if (likely(!bytes)) {
199                         kunmap_atomic(kaddr);
200                         goto done;
201                 }
202                 offset = from - kaddr;
203                 buf += copy;
204                 kunmap_atomic(kaddr);
205                 copy = min(bytes, iov->iov_len - skip);
206         }
207         /* Too bad - revert to non-atomic kmap */
208
209         kaddr = kmap(page);
210         from = kaddr + offset;
211         left = copyout(buf, from, copy);
212         copy -= left;
213         skip += copy;
214         from += copy;
215         bytes -= copy;
216         while (unlikely(!left && bytes)) {
217                 iov++;
218                 buf = iov->iov_base;
219                 copy = min(bytes, iov->iov_len);
220                 left = copyout(buf, from, copy);
221                 copy -= left;
222                 skip = copy;
223                 from += copy;
224                 bytes -= copy;
225         }
226         kunmap(page);
227
228 done:
229         if (skip == iov->iov_len) {
230                 iov++;
231                 skip = 0;
232         }
233         i->count -= wanted - bytes;
234         i->nr_segs -= iov - i->iov;
235         i->iov = iov;
236         i->iov_offset = skip;
237         return wanted - bytes;
238 }
239
240 static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t bytes,
241                          struct iov_iter *i)
242 {
243         size_t skip, copy, left, wanted;
244         const struct iovec *iov;
245         char __user *buf;
246         void *kaddr, *to;
247
248         if (unlikely(bytes > i->count))
249                 bytes = i->count;
250
251         if (unlikely(!bytes))
252                 return 0;
253
254         might_fault();
255         wanted = bytes;
256         iov = i->iov;
257         skip = i->iov_offset;
258         buf = iov->iov_base + skip;
259         copy = min(bytes, iov->iov_len - skip);
260
261         if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_readable(buf, copy)) {
262                 kaddr = kmap_atomic(page);
263                 to = kaddr + offset;
264
265                 /* first chunk, usually the only one */
266                 left = copyin(to, buf, copy);
267                 copy -= left;
268                 skip += copy;
269                 to += copy;
270                 bytes -= copy;
271
272                 while (unlikely(!left && bytes)) {
273                         iov++;
274                         buf = iov->iov_base;
275                         copy = min(bytes, iov->iov_len);
276                         left = copyin(to, buf, copy);
277                         copy -= left;
278                         skip = copy;
279                         to += copy;
280                         bytes -= copy;
281                 }
282                 if (likely(!bytes)) {
283                         kunmap_atomic(kaddr);
284                         goto done;
285                 }
286                 offset = to - kaddr;
287                 buf += copy;
288                 kunmap_atomic(kaddr);
289                 copy = min(bytes, iov->iov_len - skip);
290         }
291         /* Too bad - revert to non-atomic kmap */
292
293         kaddr = kmap(page);
294         to = kaddr + offset;
295         left = copyin(to, buf, copy);
296         copy -= left;
297         skip += copy;
298         to += copy;
299         bytes -= copy;
300         while (unlikely(!left && bytes)) {
301                 iov++;
302                 buf = iov->iov_base;
303                 copy = min(bytes, iov->iov_len);
304                 left = copyin(to, buf, copy);
305                 copy -= left;
306                 skip = copy;
307                 to += copy;
308                 bytes -= copy;
309         }
310         kunmap(page);
311
312 done:
313         if (skip == iov->iov_len) {
314                 iov++;
315                 skip = 0;
316         }
317         i->count -= wanted - bytes;
318         i->nr_segs -= iov - i->iov;
319         i->iov = iov;
320         i->iov_offset = skip;
321         return wanted - bytes;
322 }
323
324 #ifdef PIPE_PARANOIA
325 static bool sanity(const struct iov_iter *i)
326 {
327         struct pipe_inode_info *pipe = i->pipe;
328         unsigned int p_head = pipe->head;
329         unsigned int p_tail = pipe->tail;
330         unsigned int p_mask = pipe->ring_size - 1;
331         unsigned int p_occupancy = pipe_occupancy(p_head, p_tail);
332         unsigned int i_head = i->head;
333         unsigned int idx;
334
335         if (i->iov_offset) {
336                 struct pipe_buffer *p;
337                 if (unlikely(p_occupancy == 0))
338                         goto Bad;       // pipe must be non-empty
339                 if (unlikely(i_head != p_head - 1))
340                         goto Bad;       // must be at the last buffer...
341
342                 p = &pipe->bufs[i_head & p_mask];
343                 if (unlikely(p->offset + p->len != i->iov_offset))
344                         goto Bad;       // ... at the end of segment
345         } else {
346                 if (i_head != p_head)
347                         goto Bad;       // must be right after the last buffer
348         }
349         return true;
350 Bad:
351         printk(KERN_ERR "idx = %d, offset = %zd\n", i_head, i->iov_offset);
352         printk(KERN_ERR "head = %d, tail = %d, buffers = %d\n",
353                         p_head, p_tail, pipe->ring_size);
354         for (idx = 0; idx < pipe->ring_size; idx++)
355                 printk(KERN_ERR "[%p %p %d %d]\n",
356                         pipe->bufs[idx].ops,
357                         pipe->bufs[idx].page,
358                         pipe->bufs[idx].offset,
359                         pipe->bufs[idx].len);
360         WARN_ON(1);
361         return false;
362 }
363 #else
364 #define sanity(i) true
365 #endif
366
367 static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes,
368                          struct iov_iter *i)
369 {
370         struct pipe_inode_info *pipe = i->pipe;
371         struct pipe_buffer *buf;
372         unsigned int p_tail = pipe->tail;
373         unsigned int p_mask = pipe->ring_size - 1;
374         unsigned int i_head = i->head;
375         size_t off;
376
377         if (unlikely(bytes > i->count))
378                 bytes = i->count;
379
380         if (unlikely(!bytes))
381                 return 0;
382
383         if (!sanity(i))
384                 return 0;
385
386         off = i->iov_offset;
387         buf = &pipe->bufs[i_head & p_mask];
388         if (off) {
389                 if (offset == off && buf->page == page) {
390                         /* merge with the last one */
391                         buf->len += bytes;
392                         i->iov_offset += bytes;
393                         goto out;
394                 }
395                 i_head++;
396                 buf = &pipe->bufs[i_head & p_mask];
397         }
398         if (pipe_full(i_head, p_tail, pipe->max_usage))
399                 return 0;
400
401         buf->ops = &page_cache_pipe_buf_ops;
402         get_page(page);
403         buf->page = page;
404         buf->offset = offset;
405         buf->len = bytes;
406
407         pipe->head = i_head + 1;
408         i->iov_offset = offset + bytes;
409         i->head = i_head;
410 out:
411         i->count -= bytes;
412         return bytes;
413 }
414
415 /*
416  * Fault in one or more iovecs of the given iov_iter, to a maximum length of
417  * bytes.  For each iovec, fault in each page that constitutes the iovec.
418  *
419  * Return 0 on success, or non-zero if the memory could not be accessed (i.e.
420  * because it is an invalid address).
421  */
422 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
423 {
424         size_t skip = i->iov_offset;
425         const struct iovec *iov;
426         int err;
427         struct iovec v;
428
429         if (!(i->type & (ITER_BVEC|ITER_KVEC))) {
430                 iterate_iovec(i, bytes, v, iov, skip, ({
431                         err = fault_in_pages_readable(v.iov_base, v.iov_len);
432                         if (unlikely(err))
433                         return err;
434                 0;}))
435         }
436         return 0;
437 }
438 EXPORT_SYMBOL(iov_iter_fault_in_readable);
439
440 void iov_iter_init(struct iov_iter *i, unsigned int direction,
441                         const struct iovec *iov, unsigned long nr_segs,
442                         size_t count)
443 {
444         WARN_ON(direction & ~(READ | WRITE));
445         direction &= READ | WRITE;
446
447         /* It will get better.  Eventually... */
448         if (uaccess_kernel()) {
449                 i->type = ITER_KVEC | direction;
450                 i->kvec = (struct kvec *)iov;
451         } else {
452                 i->type = ITER_IOVEC | direction;
453                 i->iov = iov;
454         }
455         i->nr_segs = nr_segs;
456         i->iov_offset = 0;
457         i->count = count;
458 }
459 EXPORT_SYMBOL(iov_iter_init);
460
461 static void memcpy_from_page(char *to, struct page *page, size_t offset, size_t len)
462 {
463         char *from = kmap_atomic(page);
464         memcpy(to, from + offset, len);
465         kunmap_atomic(from);
466 }
467
468 static void memcpy_to_page(struct page *page, size_t offset, const char *from, size_t len)
469 {
470         char *to = kmap_atomic(page);
471         memcpy(to + offset, from, len);
472         kunmap_atomic(to);
473 }
474
475 static void memzero_page(struct page *page, size_t offset, size_t len)
476 {
477         char *addr = kmap_atomic(page);
478         memset(addr + offset, 0, len);
479         kunmap_atomic(addr);
480 }
481
482 static inline bool allocated(struct pipe_buffer *buf)
483 {
484         return buf->ops == &default_pipe_buf_ops;
485 }
486
487 static inline void data_start(const struct iov_iter *i,
488                               unsigned int *iter_headp, size_t *offp)
489 {
490         unsigned int p_mask = i->pipe->ring_size - 1;
491         unsigned int iter_head = i->head;
492         size_t off = i->iov_offset;
493
494         if (off && (!allocated(&i->pipe->bufs[iter_head & p_mask]) ||
495                     off == PAGE_SIZE)) {
496                 iter_head++;
497                 off = 0;
498         }
499         *iter_headp = iter_head;
500         *offp = off;
501 }
502
503 static size_t push_pipe(struct iov_iter *i, size_t size,
504                         int *iter_headp, size_t *offp)
505 {
506         struct pipe_inode_info *pipe = i->pipe;
507         unsigned int p_tail = pipe->tail;
508         unsigned int p_mask = pipe->ring_size - 1;
509         unsigned int iter_head;
510         size_t off;
511         ssize_t left;
512
513         if (unlikely(size > i->count))
514                 size = i->count;
515         if (unlikely(!size))
516                 return 0;
517
518         left = size;
519         data_start(i, &iter_head, &off);
520         *iter_headp = iter_head;
521         *offp = off;
522         if (off) {
523                 left -= PAGE_SIZE - off;
524                 if (left <= 0) {
525                         pipe->bufs[iter_head & p_mask].len += size;
526                         return size;
527                 }
528                 pipe->bufs[iter_head & p_mask].len = PAGE_SIZE;
529                 iter_head++;
530         }
531         while (!pipe_full(iter_head, p_tail, pipe->max_usage)) {
532                 struct pipe_buffer *buf = &pipe->bufs[iter_head & p_mask];
533                 struct page *page = alloc_page(GFP_USER);
534                 if (!page)
535                         break;
536
537                 buf->ops = &default_pipe_buf_ops;
538                 buf->page = page;
539                 buf->offset = 0;
540                 buf->len = min_t(ssize_t, left, PAGE_SIZE);
541                 left -= buf->len;
542                 iter_head++;
543                 pipe->head = iter_head;
544
545                 if (left == 0)
546                         return size;
547         }
548         return size - left;
549 }
550
551 static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
552                                 struct iov_iter *i)
553 {
554         struct pipe_inode_info *pipe = i->pipe;
555         unsigned int p_mask = pipe->ring_size - 1;
556         unsigned int i_head;
557         size_t n, off;
558
559         if (!sanity(i))
560                 return 0;
561
562         bytes = n = push_pipe(i, bytes, &i_head, &off);
563         if (unlikely(!n))
564                 return 0;
565         do {
566                 size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
567                 memcpy_to_page(pipe->bufs[i_head & p_mask].page, off, addr, chunk);
568                 i->head = i_head;
569                 i->iov_offset = off + chunk;
570                 n -= chunk;
571                 addr += chunk;
572                 off = 0;
573                 i_head++;
574         } while (n);
575         i->count -= bytes;
576         return bytes;
577 }
578
579 static __wsum csum_and_memcpy(void *to, const void *from, size_t len,
580                               __wsum sum, size_t off)
581 {
582         __wsum next = csum_partial_copy_nocheck(from, to, len, 0);
583         return csum_block_add(sum, next, off);
584 }
585
586 static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes,
587                                 __wsum *csum, struct iov_iter *i)
588 {
589         struct pipe_inode_info *pipe = i->pipe;
590         unsigned int p_mask = pipe->ring_size - 1;
591         unsigned int i_head;
592         size_t n, r;
593         size_t off = 0;
594         __wsum sum = *csum;
595
596         if (!sanity(i))
597                 return 0;
598
599         bytes = n = push_pipe(i, bytes, &i_head, &r);
600         if (unlikely(!n))
601                 return 0;
602         do {
603                 size_t chunk = min_t(size_t, n, PAGE_SIZE - r);
604                 char *p = kmap_atomic(pipe->bufs[i_head & p_mask].page);
605                 sum = csum_and_memcpy(p + r, addr, chunk, sum, off);
606                 kunmap_atomic(p);
607                 i->head = i_head;
608                 i->iov_offset = r + chunk;
609                 n -= chunk;
610                 off += chunk;
611                 addr += chunk;
612                 r = 0;
613                 i_head++;
614         } while (n);
615         i->count -= bytes;
616         *csum = sum;
617         return bytes;
618 }
619
620 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
621 {
622         const char *from = addr;
623         if (unlikely(iov_iter_is_pipe(i)))
624                 return copy_pipe_to_iter(addr, bytes, i);
625         if (iter_is_iovec(i))
626                 might_fault();
627         iterate_and_advance(i, bytes, v,
628                 copyout(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len),
629                 memcpy_to_page(v.bv_page, v.bv_offset,
630                                (from += v.bv_len) - v.bv_len, v.bv_len),
631                 memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len)
632         )
633
634         return bytes;
635 }
636 EXPORT_SYMBOL(_copy_to_iter);
637
638 #ifdef CONFIG_ARCH_HAS_UACCESS_MCSAFE
639 static int copyout_mcsafe(void __user *to, const void *from, size_t n)
640 {
641         if (access_ok(to, n)) {
642                 kasan_check_read(from, n);
643                 n = copy_to_user_mcsafe((__force void *) to, from, n);
644         }
645         return n;
646 }
647
648 static unsigned long memcpy_mcsafe_to_page(struct page *page, size_t offset,
649                 const char *from, size_t len)
650 {
651         unsigned long ret;
652         char *to;
653
654         to = kmap_atomic(page);
655         ret = memcpy_mcsafe(to + offset, from, len);
656         kunmap_atomic(to);
657
658         return ret;
659 }
660
661 static size_t copy_pipe_to_iter_mcsafe(const void *addr, size_t bytes,
662                                 struct iov_iter *i)
663 {
664         struct pipe_inode_info *pipe = i->pipe;
665         unsigned int p_mask = pipe->ring_size - 1;
666         unsigned int i_head;
667         size_t n, off, xfer = 0;
668
669         if (!sanity(i))
670                 return 0;
671
672         bytes = n = push_pipe(i, bytes, &i_head, &off);
673         if (unlikely(!n))
674                 return 0;
675         do {
676                 size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
677                 unsigned long rem;
678
679                 rem = memcpy_mcsafe_to_page(pipe->bufs[i_head & p_mask].page,
680                                             off, addr, chunk);
681                 i->head = i_head;
682                 i->iov_offset = off + chunk - rem;
683                 xfer += chunk - rem;
684                 if (rem)
685                         break;
686                 n -= chunk;
687                 addr += chunk;
688                 off = 0;
689                 i_head++;
690         } while (n);
691         i->count -= xfer;
692         return xfer;
693 }
694
695 /**
696  * _copy_to_iter_mcsafe - copy to user with source-read error exception handling
697  * @addr: source kernel address
698  * @bytes: total transfer length
699  * @iter: destination iterator
700  *
701  * The pmem driver arranges for filesystem-dax to use this facility via
702  * dax_copy_to_iter() for protecting read/write to persistent memory.
703  * Unless / until an architecture can guarantee identical performance
704  * between _copy_to_iter_mcsafe() and _copy_to_iter() it would be a
705  * performance regression to switch more users to the mcsafe version.
706  *
707  * Otherwise, the main differences between this and typical _copy_to_iter().
708  *
709  * * Typical tail/residue handling after a fault retries the copy
710  *   byte-by-byte until the fault happens again. Re-triggering machine
711  *   checks is potentially fatal so the implementation uses source
712  *   alignment and poison alignment assumptions to avoid re-triggering
713  *   hardware exceptions.
714  *
715  * * ITER_KVEC, ITER_PIPE, and ITER_BVEC can return short copies.
716  *   Compare to copy_to_iter() where only ITER_IOVEC attempts might return
717  *   a short copy.
718  *
719  * See MCSAFE_TEST for self-test.
720  */
721 size_t _copy_to_iter_mcsafe(const void *addr, size_t bytes, struct iov_iter *i)
722 {
723         const char *from = addr;
724         unsigned long rem, curr_addr, s_addr = (unsigned long) addr;
725
726         if (unlikely(iov_iter_is_pipe(i)))
727                 return copy_pipe_to_iter_mcsafe(addr, bytes, i);
728         if (iter_is_iovec(i))
729                 might_fault();
730         iterate_and_advance(i, bytes, v,
731                 copyout_mcsafe(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len),
732                 ({
733                 rem = memcpy_mcsafe_to_page(v.bv_page, v.bv_offset,
734                                (from += v.bv_len) - v.bv_len, v.bv_len);
735                 if (rem) {
736                         curr_addr = (unsigned long) from;
737                         bytes = curr_addr - s_addr - rem;
738                         return bytes;
739                 }
740                 }),
741                 ({
742                 rem = memcpy_mcsafe(v.iov_base, (from += v.iov_len) - v.iov_len,
743                                 v.iov_len);
744                 if (rem) {
745                         curr_addr = (unsigned long) from;
746                         bytes = curr_addr - s_addr - rem;
747                         return bytes;
748                 }
749                 })
750         )
751
752         return bytes;
753 }
754 EXPORT_SYMBOL_GPL(_copy_to_iter_mcsafe);
755 #endif /* CONFIG_ARCH_HAS_UACCESS_MCSAFE */
756
757 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
758 {
759         char *to = addr;
760         if (unlikely(iov_iter_is_pipe(i))) {
761                 WARN_ON(1);
762                 return 0;
763         }
764         if (iter_is_iovec(i))
765                 might_fault();
766         iterate_and_advance(i, bytes, v,
767                 copyin((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
768                 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
769                                  v.bv_offset, v.bv_len),
770                 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
771         )
772
773         return bytes;
774 }
775 EXPORT_SYMBOL(_copy_from_iter);
776
777 bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
778 {
779         char *to = addr;
780         if (unlikely(iov_iter_is_pipe(i))) {
781                 WARN_ON(1);
782                 return false;
783         }
784         if (unlikely(i->count < bytes))
785                 return false;
786
787         if (iter_is_iovec(i))
788                 might_fault();
789         iterate_all_kinds(i, bytes, v, ({
790                 if (copyin((to += v.iov_len) - v.iov_len,
791                                       v.iov_base, v.iov_len))
792                         return false;
793                 0;}),
794                 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
795                                  v.bv_offset, v.bv_len),
796                 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
797         )
798
799         iov_iter_advance(i, bytes);
800         return true;
801 }
802 EXPORT_SYMBOL(_copy_from_iter_full);
803
804 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
805 {
806         char *to = addr;
807         if (unlikely(iov_iter_is_pipe(i))) {
808                 WARN_ON(1);
809                 return 0;
810         }
811         iterate_and_advance(i, bytes, v,
812                 __copy_from_user_inatomic_nocache((to += v.iov_len) - v.iov_len,
813                                          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                 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
817         )
818
819         return bytes;
820 }
821 EXPORT_SYMBOL(_copy_from_iter_nocache);
822
823 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
824 /**
825  * _copy_from_iter_flushcache - write destination through cpu cache
826  * @addr: destination kernel address
827  * @bytes: total transfer length
828  * @iter: source iterator
829  *
830  * The pmem driver arranges for filesystem-dax to use this facility via
831  * dax_copy_from_iter() for ensuring that writes to persistent memory
832  * are flushed through the CPU cache. It is differentiated from
833  * _copy_from_iter_nocache() in that guarantees all data is flushed for
834  * all iterator types. The _copy_from_iter_nocache() only attempts to
835  * bypass the cache for the ITER_IOVEC case, and on some archs may use
836  * instructions that strand dirty-data in the cache.
837  */
838 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
839 {
840         char *to = addr;
841         if (unlikely(iov_iter_is_pipe(i))) {
842                 WARN_ON(1);
843                 return 0;
844         }
845         iterate_and_advance(i, bytes, v,
846                 __copy_from_user_flushcache((to += v.iov_len) - v.iov_len,
847                                          v.iov_base, v.iov_len),
848                 memcpy_page_flushcache((to += v.bv_len) - v.bv_len, v.bv_page,
849                                  v.bv_offset, v.bv_len),
850                 memcpy_flushcache((to += v.iov_len) - v.iov_len, v.iov_base,
851                         v.iov_len)
852         )
853
854         return bytes;
855 }
856 EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache);
857 #endif
858
859 bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
860 {
861         char *to = addr;
862         if (unlikely(iov_iter_is_pipe(i))) {
863                 WARN_ON(1);
864                 return false;
865         }
866         if (unlikely(i->count < bytes))
867                 return false;
868         iterate_all_kinds(i, bytes, v, ({
869                 if (__copy_from_user_inatomic_nocache((to += v.iov_len) - v.iov_len,
870                                              v.iov_base, v.iov_len))
871                         return false;
872                 0;}),
873                 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
874                                  v.bv_offset, v.bv_len),
875                 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
876         )
877
878         iov_iter_advance(i, bytes);
879         return true;
880 }
881 EXPORT_SYMBOL(_copy_from_iter_full_nocache);
882
883 static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
884 {
885         struct page *head;
886         size_t v = n + offset;
887
888         /*
889          * The general case needs to access the page order in order
890          * to compute the page size.
891          * However, we mostly deal with order-0 pages and thus can
892          * avoid a possible cache line miss for requests that fit all
893          * page orders.
894          */
895         if (n <= v && v <= PAGE_SIZE)
896                 return true;
897
898         head = compound_head(page);
899         v += (page - head) << PAGE_SHIFT;
900
901         if (likely(n <= v && v <= (page_size(head))))
902                 return true;
903         WARN_ON(1);
904         return false;
905 }
906
907 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
908                          struct iov_iter *i)
909 {
910         if (unlikely(!page_copy_sane(page, offset, bytes)))
911                 return 0;
912         if (i->type & (ITER_BVEC|ITER_KVEC)) {
913                 void *kaddr = kmap_atomic(page);
914                 size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
915                 kunmap_atomic(kaddr);
916                 return wanted;
917         } else if (unlikely(iov_iter_is_discard(i)))
918                 return bytes;
919         else if (likely(!iov_iter_is_pipe(i)))
920                 return copy_page_to_iter_iovec(page, offset, bytes, i);
921         else
922                 return copy_page_to_iter_pipe(page, offset, bytes, i);
923 }
924 EXPORT_SYMBOL(copy_page_to_iter);
925
926 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
927                          struct iov_iter *i)
928 {
929         if (unlikely(!page_copy_sane(page, offset, bytes)))
930                 return 0;
931         if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
932                 WARN_ON(1);
933                 return 0;
934         }
935         if (i->type & (ITER_BVEC|ITER_KVEC)) {
936                 void *kaddr = kmap_atomic(page);
937                 size_t wanted = _copy_from_iter(kaddr + offset, bytes, i);
938                 kunmap_atomic(kaddr);
939                 return wanted;
940         } else
941                 return copy_page_from_iter_iovec(page, offset, bytes, i);
942 }
943 EXPORT_SYMBOL(copy_page_from_iter);
944
945 static size_t pipe_zero(size_t bytes, struct iov_iter *i)
946 {
947         struct pipe_inode_info *pipe = i->pipe;
948         unsigned int p_mask = pipe->ring_size - 1;
949         unsigned int i_head;
950         size_t n, off;
951
952         if (!sanity(i))
953                 return 0;
954
955         bytes = n = push_pipe(i, bytes, &i_head, &off);
956         if (unlikely(!n))
957                 return 0;
958
959         do {
960                 size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
961                 memzero_page(pipe->bufs[i_head & p_mask].page, off, chunk);
962                 i->head = i_head;
963                 i->iov_offset = off + chunk;
964                 n -= chunk;
965                 off = 0;
966                 i_head++;
967         } while (n);
968         i->count -= bytes;
969         return bytes;
970 }
971
972 size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
973 {
974         if (unlikely(iov_iter_is_pipe(i)))
975                 return pipe_zero(bytes, i);
976         iterate_and_advance(i, bytes, v,
977                 clear_user(v.iov_base, v.iov_len),
978                 memzero_page(v.bv_page, v.bv_offset, v.bv_len),
979                 memset(v.iov_base, 0, v.iov_len)
980         )
981
982         return bytes;
983 }
984 EXPORT_SYMBOL(iov_iter_zero);
985
986 size_t iov_iter_copy_from_user_atomic(struct page *page,
987                 struct iov_iter *i, unsigned long offset, size_t bytes)
988 {
989         char *kaddr = kmap_atomic(page), *p = kaddr + offset;
990         if (unlikely(!page_copy_sane(page, offset, bytes))) {
991                 kunmap_atomic(kaddr);
992                 return 0;
993         }
994         if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
995                 kunmap_atomic(kaddr);
996                 WARN_ON(1);
997                 return 0;
998         }
999         iterate_all_kinds(i, bytes, v,
1000                 copyin((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
1001                 memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page,
1002                                  v.bv_offset, v.bv_len),
1003                 memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
1004         )
1005         kunmap_atomic(kaddr);
1006         return bytes;
1007 }
1008 EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
1009
1010 static inline void pipe_truncate(struct iov_iter *i)
1011 {
1012         struct pipe_inode_info *pipe = i->pipe;
1013         unsigned int p_tail = pipe->tail;
1014         unsigned int p_head = pipe->head;
1015         unsigned int p_mask = pipe->ring_size - 1;
1016
1017         if (!pipe_empty(p_head, p_tail)) {
1018                 struct pipe_buffer *buf;
1019                 unsigned int i_head = i->head;
1020                 size_t off = i->iov_offset;
1021
1022                 if (off) {
1023                         buf = &pipe->bufs[i_head & p_mask];
1024                         buf->len = off - buf->offset;
1025                         i_head++;
1026                 }
1027                 while (p_head != i_head) {
1028                         p_head--;
1029                         pipe_buf_release(pipe, &pipe->bufs[p_head & p_mask]);
1030                 }
1031
1032                 pipe->head = p_head;
1033         }
1034 }
1035
1036 static void pipe_advance(struct iov_iter *i, size_t size)
1037 {
1038         struct pipe_inode_info *pipe = i->pipe;
1039         if (unlikely(i->count < size))
1040                 size = i->count;
1041         if (size) {
1042                 struct pipe_buffer *buf;
1043                 unsigned int p_mask = pipe->ring_size - 1;
1044                 unsigned int i_head = i->head;
1045                 size_t off = i->iov_offset, left = size;
1046
1047                 if (off) /* make it relative to the beginning of buffer */
1048                         left += off - pipe->bufs[i_head & p_mask].offset;
1049                 while (1) {
1050                         buf = &pipe->bufs[i_head & p_mask];
1051                         if (left <= buf->len)
1052                                 break;
1053                         left -= buf->len;
1054                         i_head++;
1055                 }
1056                 i->head = i_head;
1057                 i->iov_offset = buf->offset + left;
1058         }
1059         i->count -= size;
1060         /* ... and discard everything past that point */
1061         pipe_truncate(i);
1062 }
1063
1064 void iov_iter_advance(struct iov_iter *i, size_t size)
1065 {
1066         if (unlikely(iov_iter_is_pipe(i))) {
1067                 pipe_advance(i, size);
1068                 return;
1069         }
1070         if (unlikely(iov_iter_is_discard(i))) {
1071                 i->count -= size;
1072                 return;
1073         }
1074         iterate_and_advance(i, size, v, 0, 0, 0)
1075 }
1076 EXPORT_SYMBOL(iov_iter_advance);
1077
1078 void iov_iter_revert(struct iov_iter *i, size_t unroll)
1079 {
1080         if (!unroll)
1081                 return;
1082         if (WARN_ON(unroll > MAX_RW_COUNT))
1083                 return;
1084         i->count += unroll;
1085         if (unlikely(iov_iter_is_pipe(i))) {
1086                 struct pipe_inode_info *pipe = i->pipe;
1087                 unsigned int p_mask = pipe->ring_size - 1;
1088                 unsigned int i_head = i->head;
1089                 size_t off = i->iov_offset;
1090                 while (1) {
1091                         struct pipe_buffer *b = &pipe->bufs[i_head & p_mask];
1092                         size_t n = off - b->offset;
1093                         if (unroll < n) {
1094                                 off -= unroll;
1095                                 break;
1096                         }
1097                         unroll -= n;
1098                         if (!unroll && i_head == i->start_head) {
1099                                 off = 0;
1100                                 break;
1101                         }
1102                         i_head--;
1103                         b = &pipe->bufs[i_head & p_mask];
1104                         off = b->offset + b->len;
1105                 }
1106                 i->iov_offset = off;
1107                 i->head = i_head;
1108                 pipe_truncate(i);
1109                 return;
1110         }
1111         if (unlikely(iov_iter_is_discard(i)))
1112                 return;
1113         if (unroll <= i->iov_offset) {
1114                 i->iov_offset -= unroll;
1115                 return;
1116         }
1117         unroll -= i->iov_offset;
1118         if (iov_iter_is_bvec(i)) {
1119                 const struct bio_vec *bvec = i->bvec;
1120                 while (1) {
1121                         size_t n = (--bvec)->bv_len;
1122                         i->nr_segs++;
1123                         if (unroll <= n) {
1124                                 i->bvec = bvec;
1125                                 i->iov_offset = n - unroll;
1126                                 return;
1127                         }
1128                         unroll -= n;
1129                 }
1130         } else { /* same logics for iovec and kvec */
1131                 const struct iovec *iov = i->iov;
1132                 while (1) {
1133                         size_t n = (--iov)->iov_len;
1134                         i->nr_segs++;
1135                         if (unroll <= n) {
1136                                 i->iov = iov;
1137                                 i->iov_offset = n - unroll;
1138                                 return;
1139                         }
1140                         unroll -= n;
1141                 }
1142         }
1143 }
1144 EXPORT_SYMBOL(iov_iter_revert);
1145
1146 /*
1147  * Return the count of just the current iov_iter segment.
1148  */
1149 size_t iov_iter_single_seg_count(const struct iov_iter *i)
1150 {
1151         if (unlikely(iov_iter_is_pipe(i)))
1152                 return i->count;        // it is a silly place, anyway
1153         if (i->nr_segs == 1)
1154                 return i->count;
1155         if (unlikely(iov_iter_is_discard(i)))
1156                 return i->count;
1157         else if (iov_iter_is_bvec(i))
1158                 return min(i->count, i->bvec->bv_len - i->iov_offset);
1159         else
1160                 return min(i->count, i->iov->iov_len - i->iov_offset);
1161 }
1162 EXPORT_SYMBOL(iov_iter_single_seg_count);
1163
1164 void iov_iter_kvec(struct iov_iter *i, unsigned int direction,
1165                         const struct kvec *kvec, unsigned long nr_segs,
1166                         size_t count)
1167 {
1168         WARN_ON(direction & ~(READ | WRITE));
1169         i->type = ITER_KVEC | (direction & (READ | WRITE));
1170         i->kvec = kvec;
1171         i->nr_segs = nr_segs;
1172         i->iov_offset = 0;
1173         i->count = count;
1174 }
1175 EXPORT_SYMBOL(iov_iter_kvec);
1176
1177 void iov_iter_bvec(struct iov_iter *i, unsigned int direction,
1178                         const struct bio_vec *bvec, unsigned long nr_segs,
1179                         size_t count)
1180 {
1181         WARN_ON(direction & ~(READ | WRITE));
1182         i->type = ITER_BVEC | (direction & (READ | WRITE));
1183         i->bvec = bvec;
1184         i->nr_segs = nr_segs;
1185         i->iov_offset = 0;
1186         i->count = count;
1187 }
1188 EXPORT_SYMBOL(iov_iter_bvec);
1189
1190 void iov_iter_pipe(struct iov_iter *i, unsigned int direction,
1191                         struct pipe_inode_info *pipe,
1192                         size_t count)
1193 {
1194         BUG_ON(direction != READ);
1195         WARN_ON(pipe_full(pipe->head, pipe->tail, pipe->ring_size));
1196         i->type = ITER_PIPE | READ;
1197         i->pipe = pipe;
1198         i->head = pipe->head;
1199         i->iov_offset = 0;
1200         i->count = count;
1201         i->start_head = i->head;
1202 }
1203 EXPORT_SYMBOL(iov_iter_pipe);
1204
1205 /**
1206  * iov_iter_discard - Initialise an I/O iterator that discards data
1207  * @i: The iterator to initialise.
1208  * @direction: The direction of the transfer.
1209  * @count: The size of the I/O buffer in bytes.
1210  *
1211  * Set up an I/O iterator that just discards everything that's written to it.
1212  * It's only available as a READ iterator.
1213  */
1214 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count)
1215 {
1216         BUG_ON(direction != READ);
1217         i->type = ITER_DISCARD | READ;
1218         i->count = count;
1219         i->iov_offset = 0;
1220 }
1221 EXPORT_SYMBOL(iov_iter_discard);
1222
1223 unsigned long iov_iter_alignment(const struct iov_iter *i)
1224 {
1225         unsigned long res = 0;
1226         size_t size = i->count;
1227
1228         if (unlikely(iov_iter_is_pipe(i))) {
1229                 unsigned int p_mask = i->pipe->ring_size - 1;
1230
1231                 if (size && i->iov_offset && allocated(&i->pipe->bufs[i->head & p_mask]))
1232                         return size | i->iov_offset;
1233                 return size;
1234         }
1235         iterate_all_kinds(i, size, v,
1236                 (res |= (unsigned long)v.iov_base | v.iov_len, 0),
1237                 res |= v.bv_offset | v.bv_len,
1238                 res |= (unsigned long)v.iov_base | v.iov_len
1239         )
1240         return res;
1241 }
1242 EXPORT_SYMBOL(iov_iter_alignment);
1243
1244 unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
1245 {
1246         unsigned long res = 0;
1247         size_t size = i->count;
1248
1249         if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
1250                 WARN_ON(1);
1251                 return ~0U;
1252         }
1253
1254         iterate_all_kinds(i, size, v,
1255                 (res |= (!res ? 0 : (unsigned long)v.iov_base) |
1256                         (size != v.iov_len ? size : 0), 0),
1257                 (res |= (!res ? 0 : (unsigned long)v.bv_offset) |
1258                         (size != v.bv_len ? size : 0)),
1259                 (res |= (!res ? 0 : (unsigned long)v.iov_base) |
1260                         (size != v.iov_len ? size : 0))
1261                 );
1262         return res;
1263 }
1264 EXPORT_SYMBOL(iov_iter_gap_alignment);
1265
1266 static inline ssize_t __pipe_get_pages(struct iov_iter *i,
1267                                 size_t maxsize,
1268                                 struct page **pages,
1269                                 int iter_head,
1270                                 size_t *start)
1271 {
1272         struct pipe_inode_info *pipe = i->pipe;
1273         unsigned int p_mask = pipe->ring_size - 1;
1274         ssize_t n = push_pipe(i, maxsize, &iter_head, start);
1275         if (!n)
1276                 return -EFAULT;
1277
1278         maxsize = n;
1279         n += *start;
1280         while (n > 0) {
1281                 get_page(*pages++ = pipe->bufs[iter_head & p_mask].page);
1282                 iter_head++;
1283                 n -= PAGE_SIZE;
1284         }
1285
1286         return maxsize;
1287 }
1288
1289 static ssize_t pipe_get_pages(struct iov_iter *i,
1290                    struct page **pages, size_t maxsize, unsigned maxpages,
1291                    size_t *start)
1292 {
1293         unsigned int iter_head, npages;
1294         size_t capacity;
1295
1296         if (!maxsize)
1297                 return 0;
1298
1299         if (!sanity(i))
1300                 return -EFAULT;
1301
1302         data_start(i, &iter_head, start);
1303         /* Amount of free space: some of this one + all after this one */
1304         npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
1305         capacity = min(npages, maxpages) * PAGE_SIZE - *start;
1306
1307         return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, start);
1308 }
1309
1310 ssize_t iov_iter_get_pages(struct iov_iter *i,
1311                    struct page **pages, size_t maxsize, unsigned maxpages,
1312                    size_t *start)
1313 {
1314         if (maxsize > i->count)
1315                 maxsize = i->count;
1316
1317         if (unlikely(iov_iter_is_pipe(i)))
1318                 return pipe_get_pages(i, pages, maxsize, maxpages, start);
1319         if (unlikely(iov_iter_is_discard(i)))
1320                 return -EFAULT;
1321
1322         iterate_all_kinds(i, maxsize, v, ({
1323                 unsigned long addr = (unsigned long)v.iov_base;
1324                 size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
1325                 int n;
1326                 int res;
1327
1328                 if (len > maxpages * PAGE_SIZE)
1329                         len = maxpages * PAGE_SIZE;
1330                 addr &= ~(PAGE_SIZE - 1);
1331                 n = DIV_ROUND_UP(len, PAGE_SIZE);
1332                 res = get_user_pages_fast(addr, n,
1333                                 iov_iter_rw(i) != WRITE ?  FOLL_WRITE : 0,
1334                                 pages);
1335                 if (unlikely(res < 0))
1336                         return res;
1337                 return (res == n ? len : res * PAGE_SIZE) - *start;
1338         0;}),({
1339                 /* can't be more than PAGE_SIZE */
1340                 *start = v.bv_offset;
1341                 get_page(*pages = v.bv_page);
1342                 return v.bv_len;
1343         }),({
1344                 return -EFAULT;
1345         })
1346         )
1347         return 0;
1348 }
1349 EXPORT_SYMBOL(iov_iter_get_pages);
1350
1351 static struct page **get_pages_array(size_t n)
1352 {
1353         return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL);
1354 }
1355
1356 static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
1357                    struct page ***pages, size_t maxsize,
1358                    size_t *start)
1359 {
1360         struct page **p;
1361         unsigned int iter_head, npages;
1362         ssize_t n;
1363
1364         if (!maxsize)
1365                 return 0;
1366
1367         if (!sanity(i))
1368                 return -EFAULT;
1369
1370         data_start(i, &iter_head, start);
1371         /* Amount of free space: some of this one + all after this one */
1372         npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
1373         n = npages * PAGE_SIZE - *start;
1374         if (maxsize > n)
1375                 maxsize = n;
1376         else
1377                 npages = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
1378         p = get_pages_array(npages);
1379         if (!p)
1380                 return -ENOMEM;
1381         n = __pipe_get_pages(i, maxsize, p, iter_head, start);
1382         if (n > 0)
1383                 *pages = p;
1384         else
1385                 kvfree(p);
1386         return n;
1387 }
1388
1389 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
1390                    struct page ***pages, size_t maxsize,
1391                    size_t *start)
1392 {
1393         struct page **p;
1394
1395         if (maxsize > i->count)
1396                 maxsize = i->count;
1397
1398         if (unlikely(iov_iter_is_pipe(i)))
1399                 return pipe_get_pages_alloc(i, pages, maxsize, start);
1400         if (unlikely(iov_iter_is_discard(i)))
1401                 return -EFAULT;
1402
1403         iterate_all_kinds(i, maxsize, v, ({
1404                 unsigned long addr = (unsigned long)v.iov_base;
1405                 size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
1406                 int n;
1407                 int res;
1408
1409                 addr &= ~(PAGE_SIZE - 1);
1410                 n = DIV_ROUND_UP(len, PAGE_SIZE);
1411                 p = get_pages_array(n);
1412                 if (!p)
1413                         return -ENOMEM;
1414                 res = get_user_pages_fast(addr, n,
1415                                 iov_iter_rw(i) != WRITE ?  FOLL_WRITE : 0, p);
1416                 if (unlikely(res < 0)) {
1417                         kvfree(p);
1418                         return res;
1419                 }
1420                 *pages = p;
1421                 return (res == n ? len : res * PAGE_SIZE) - *start;
1422         0;}),({
1423                 /* can't be more than PAGE_SIZE */
1424                 *start = v.bv_offset;
1425                 *pages = p = get_pages_array(1);
1426                 if (!p)
1427                         return -ENOMEM;
1428                 get_page(*p = v.bv_page);
1429                 return v.bv_len;
1430         }),({
1431                 return -EFAULT;
1432         })
1433         )
1434         return 0;
1435 }
1436 EXPORT_SYMBOL(iov_iter_get_pages_alloc);
1437
1438 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
1439                                struct iov_iter *i)
1440 {
1441         char *to = addr;
1442         __wsum sum, next;
1443         size_t off = 0;
1444         sum = *csum;
1445         if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
1446                 WARN_ON(1);
1447                 return 0;
1448         }
1449         iterate_and_advance(i, bytes, v, ({
1450                 int err = 0;
1451                 next = csum_and_copy_from_user(v.iov_base,
1452                                                (to += v.iov_len) - v.iov_len,
1453                                                v.iov_len, 0, &err);
1454                 if (!err) {
1455                         sum = csum_block_add(sum, next, off);
1456                         off += v.iov_len;
1457                 }
1458                 err ? v.iov_len : 0;
1459         }), ({
1460                 char *p = kmap_atomic(v.bv_page);
1461                 sum = csum_and_memcpy((to += v.bv_len) - v.bv_len,
1462                                       p + v.bv_offset, v.bv_len,
1463                                       sum, off);
1464                 kunmap_atomic(p);
1465                 off += v.bv_len;
1466         }),({
1467                 sum = csum_and_memcpy((to += v.iov_len) - v.iov_len,
1468                                       v.iov_base, v.iov_len,
1469                                       sum, off);
1470                 off += v.iov_len;
1471         })
1472         )
1473         *csum = sum;
1474         return bytes;
1475 }
1476 EXPORT_SYMBOL(csum_and_copy_from_iter);
1477
1478 bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum,
1479                                struct iov_iter *i)
1480 {
1481         char *to = addr;
1482         __wsum sum, next;
1483         size_t off = 0;
1484         sum = *csum;
1485         if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
1486                 WARN_ON(1);
1487                 return false;
1488         }
1489         if (unlikely(i->count < bytes))
1490                 return false;
1491         iterate_all_kinds(i, bytes, v, ({
1492                 int err = 0;
1493                 next = csum_and_copy_from_user(v.iov_base,
1494                                                (to += v.iov_len) - v.iov_len,
1495                                                v.iov_len, 0, &err);
1496                 if (err)
1497                         return false;
1498                 sum = csum_block_add(sum, next, off);
1499                 off += v.iov_len;
1500                 0;
1501         }), ({
1502                 char *p = kmap_atomic(v.bv_page);
1503                 sum = csum_and_memcpy((to += v.bv_len) - v.bv_len,
1504                                       p + v.bv_offset, v.bv_len,
1505                                       sum, off);
1506                 kunmap_atomic(p);
1507                 off += v.bv_len;
1508         }),({
1509                 sum = csum_and_memcpy((to += v.iov_len) - v.iov_len,
1510                                       v.iov_base, v.iov_len,
1511                                       sum, off);
1512                 off += v.iov_len;
1513         })
1514         )
1515         *csum = sum;
1516         iov_iter_advance(i, bytes);
1517         return true;
1518 }
1519 EXPORT_SYMBOL(csum_and_copy_from_iter_full);
1520
1521 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csump,
1522                              struct iov_iter *i)
1523 {
1524         const char *from = addr;
1525         __wsum *csum = csump;
1526         __wsum sum, next;
1527         size_t off = 0;
1528
1529         if (unlikely(iov_iter_is_pipe(i)))
1530                 return csum_and_copy_to_pipe_iter(addr, bytes, csum, i);
1531
1532         sum = *csum;
1533         if (unlikely(iov_iter_is_discard(i))) {
1534                 WARN_ON(1);     /* for now */
1535                 return 0;
1536         }
1537         iterate_and_advance(i, bytes, v, ({
1538                 int err = 0;
1539                 next = csum_and_copy_to_user((from += v.iov_len) - v.iov_len,
1540                                              v.iov_base,
1541                                              v.iov_len, 0, &err);
1542                 if (!err) {
1543                         sum = csum_block_add(sum, next, off);
1544                         off += v.iov_len;
1545                 }
1546                 err ? v.iov_len : 0;
1547         }), ({
1548                 char *p = kmap_atomic(v.bv_page);
1549                 sum = csum_and_memcpy(p + v.bv_offset,
1550                                       (from += v.bv_len) - v.bv_len,
1551                                       v.bv_len, sum, off);
1552                 kunmap_atomic(p);
1553                 off += v.bv_len;
1554         }),({
1555                 sum = csum_and_memcpy(v.iov_base,
1556                                      (from += v.iov_len) - v.iov_len,
1557                                      v.iov_len, sum, off);
1558                 off += v.iov_len;
1559         })
1560         )
1561         *csum = sum;
1562         return bytes;
1563 }
1564 EXPORT_SYMBOL(csum_and_copy_to_iter);
1565
1566 size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
1567                 struct iov_iter *i)
1568 {
1569 #ifdef CONFIG_CRYPTO
1570         struct ahash_request *hash = hashp;
1571         struct scatterlist sg;
1572         size_t copied;
1573
1574         copied = copy_to_iter(addr, bytes, i);
1575         sg_init_one(&sg, addr, copied);
1576         ahash_request_set_crypt(hash, &sg, NULL, copied);
1577         crypto_ahash_update(hash);
1578         return copied;
1579 #else
1580         return 0;
1581 #endif
1582 }
1583 EXPORT_SYMBOL(hash_and_copy_to_iter);
1584
1585 int iov_iter_npages(const struct iov_iter *i, int maxpages)
1586 {
1587         size_t size = i->count;
1588         int npages = 0;
1589
1590         if (!size)
1591                 return 0;
1592         if (unlikely(iov_iter_is_discard(i)))
1593                 return 0;
1594
1595         if (unlikely(iov_iter_is_pipe(i))) {
1596                 struct pipe_inode_info *pipe = i->pipe;
1597                 unsigned int iter_head;
1598                 size_t off;
1599
1600                 if (!sanity(i))
1601                         return 0;
1602
1603                 data_start(i, &iter_head, &off);
1604                 /* some of this one + all after this one */
1605                 npages = pipe_space_for_user(iter_head, pipe->tail, pipe);
1606                 if (npages >= maxpages)
1607                         return maxpages;
1608         } else iterate_all_kinds(i, size, v, ({
1609                 unsigned long p = (unsigned long)v.iov_base;
1610                 npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
1611                         - p / PAGE_SIZE;
1612                 if (npages >= maxpages)
1613                         return maxpages;
1614         0;}),({
1615                 npages++;
1616                 if (npages >= maxpages)
1617                         return maxpages;
1618         }),({
1619                 unsigned long p = (unsigned long)v.iov_base;
1620                 npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
1621                         - p / PAGE_SIZE;
1622                 if (npages >= maxpages)
1623                         return maxpages;
1624         })
1625         )
1626         return npages;
1627 }
1628 EXPORT_SYMBOL(iov_iter_npages);
1629
1630 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
1631 {
1632         *new = *old;
1633         if (unlikely(iov_iter_is_pipe(new))) {
1634                 WARN_ON(1);
1635                 return NULL;
1636         }
1637         if (unlikely(iov_iter_is_discard(new)))
1638                 return NULL;
1639         if (iov_iter_is_bvec(new))
1640                 return new->bvec = kmemdup(new->bvec,
1641                                     new->nr_segs * sizeof(struct bio_vec),
1642                                     flags);
1643         else
1644                 /* iovec and kvec have identical layout */
1645                 return new->iov = kmemdup(new->iov,
1646                                    new->nr_segs * sizeof(struct iovec),
1647                                    flags);
1648 }
1649 EXPORT_SYMBOL(dup_iter);
1650
1651 /**
1652  * import_iovec() - Copy an array of &struct iovec from userspace
1653  *     into the kernel, check that it is valid, and initialize a new
1654  *     &struct iov_iter iterator to access it.
1655  *
1656  * @type: One of %READ or %WRITE.
1657  * @uvector: Pointer to the userspace array.
1658  * @nr_segs: Number of elements in userspace array.
1659  * @fast_segs: Number of elements in @iov.
1660  * @iov: (input and output parameter) Pointer to pointer to (usually small
1661  *     on-stack) kernel array.
1662  * @i: Pointer to iterator that will be initialized on success.
1663  *
1664  * If the array pointed to by *@iov is large enough to hold all @nr_segs,
1665  * then this function places %NULL in *@iov on return. Otherwise, a new
1666  * array will be allocated and the result placed in *@iov. This means that
1667  * the caller may call kfree() on *@iov regardless of whether the small
1668  * on-stack array was used or not (and regardless of whether this function
1669  * returns an error or not).
1670  *
1671  * Return: Negative error code on error, bytes imported on success
1672  */
1673 ssize_t import_iovec(int type, const struct iovec __user * uvector,
1674                  unsigned nr_segs, unsigned fast_segs,
1675                  struct iovec **iov, struct iov_iter *i)
1676 {
1677         ssize_t n;
1678         struct iovec *p;
1679         n = rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
1680                                   *iov, &p);
1681         if (n < 0) {
1682                 if (p != *iov)
1683                         kfree(p);
1684                 *iov = NULL;
1685                 return n;
1686         }
1687         iov_iter_init(i, type, p, nr_segs, n);
1688         *iov = p == *iov ? NULL : p;
1689         return n;
1690 }
1691 EXPORT_SYMBOL(import_iovec);
1692
1693 #ifdef CONFIG_COMPAT
1694 #include <linux/compat.h>
1695
1696 ssize_t compat_import_iovec(int type,
1697                 const struct compat_iovec __user * uvector,
1698                 unsigned nr_segs, unsigned fast_segs,
1699                 struct iovec **iov, struct iov_iter *i)
1700 {
1701         ssize_t n;
1702         struct iovec *p;
1703         n = compat_rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
1704                                   *iov, &p);
1705         if (n < 0) {
1706                 if (p != *iov)
1707                         kfree(p);
1708                 *iov = NULL;
1709                 return n;
1710         }
1711         iov_iter_init(i, type, p, nr_segs, n);
1712         *iov = p == *iov ? NULL : p;
1713         return n;
1714 }
1715 EXPORT_SYMBOL(compat_import_iovec);
1716 #endif
1717
1718 int import_single_range(int rw, void __user *buf, size_t len,
1719                  struct iovec *iov, struct iov_iter *i)
1720 {
1721         if (len > MAX_RW_COUNT)
1722                 len = MAX_RW_COUNT;
1723         if (unlikely(!access_ok(buf, len)))
1724                 return -EFAULT;
1725
1726         iov->iov_base = buf;
1727         iov->iov_len = len;
1728         iov_iter_init(i, rw, iov, 1, len);
1729         return 0;
1730 }
1731 EXPORT_SYMBOL(import_single_range);
1732
1733 int iov_iter_for_each_range(struct iov_iter *i, size_t bytes,
1734                             int (*f)(struct kvec *vec, void *context),
1735                             void *context)
1736 {
1737         struct kvec w;
1738         int err = -EINVAL;
1739         if (!bytes)
1740                 return 0;
1741
1742         iterate_all_kinds(i, bytes, v, -EINVAL, ({
1743                 w.iov_base = kmap(v.bv_page) + v.bv_offset;
1744                 w.iov_len = v.bv_len;
1745                 err = f(&w, context);
1746                 kunmap(v.bv_page);
1747                 err;}), ({
1748                 w = v;
1749                 err = f(&w, context);})
1750         )
1751         return err;
1752 }
1753 EXPORT_SYMBOL(iov_iter_for_each_range);