1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <crypto/hash.h>
3 #include <linux/export.h>
4 #include <linux/bvec.h>
5 #include <linux/fault-inject-usercopy.h>
7 #include <linux/pagemap.h>
8 #include <linux/highmem.h>
9 #include <linux/slab.h>
10 #include <linux/vmalloc.h>
11 #include <linux/splice.h>
12 #include <linux/compat.h>
13 #include <net/checksum.h>
14 #include <linux/scatterlist.h>
15 #include <linux/instrumented.h>
17 #define PIPE_PARANOIA /* for now */
19 /* covers iovec and kvec alike */
20 #define iterate_iovec(i, n, base, len, off, __p, STEP) { \
22 size_t skip = i->iov_offset; \
24 len = min(n, __p->iov_len - skip); \
26 base = __p->iov_base + skip; \
31 if (skip < __p->iov_len) \
37 i->iov_offset = skip; \
41 #define iterate_bvec(i, n, base, len, off, p, STEP) { \
43 unsigned skip = i->iov_offset; \
45 unsigned offset = p->bv_offset + skip; \
47 void *kaddr = kmap_local_page(p->bv_page + \
48 offset / PAGE_SIZE); \
49 base = kaddr + offset % PAGE_SIZE; \
50 len = min(min(n, (size_t)(p->bv_len - skip)), \
51 (size_t)(PAGE_SIZE - offset % PAGE_SIZE)); \
53 kunmap_local(kaddr); \
57 if (skip == p->bv_len) { \
65 i->iov_offset = skip; \
69 #define iterate_xarray(i, n, base, len, __off, STEP) { \
72 struct page *head = NULL; \
73 loff_t start = i->xarray_start + i->iov_offset; \
74 unsigned offset = start % PAGE_SIZE; \
75 pgoff_t index = start / PAGE_SIZE; \
78 XA_STATE(xas, i->xarray, index); \
81 xas_for_each(&xas, head, ULONG_MAX) { \
83 if (xas_retry(&xas, head)) \
85 if (WARN_ON(xa_is_value(head))) \
87 if (WARN_ON(PageHuge(head))) \
89 for (j = (head->index < index) ? index - head->index : 0; \
90 j < thp_nr_pages(head); j++) { \
91 void *kaddr = kmap_local_page(head + j); \
92 base = kaddr + offset; \
93 len = PAGE_SIZE - offset; \
96 kunmap_local(kaddr); \
100 if (left || n == 0) \
107 i->iov_offset += __off; \
111 #define __iterate_and_advance(i, n, base, len, off, I, K) { \
112 if (unlikely(i->count < n)) \
115 if (likely(iter_is_iovec(i))) { \
116 const struct iovec *iov = i->iov; \
119 iterate_iovec(i, n, base, len, off, \
121 i->nr_segs -= iov - i->iov; \
123 } else if (iov_iter_is_bvec(i)) { \
124 const struct bio_vec *bvec = i->bvec; \
127 iterate_bvec(i, n, base, len, off, \
129 i->nr_segs -= bvec - i->bvec; \
131 } else if (iov_iter_is_kvec(i)) { \
132 const struct kvec *kvec = i->kvec; \
135 iterate_iovec(i, n, base, len, off, \
137 i->nr_segs -= kvec - i->kvec; \
139 } else if (iov_iter_is_xarray(i)) { \
142 iterate_xarray(i, n, base, len, off, \
148 #define iterate_and_advance(i, n, base, len, off, I, K) \
149 __iterate_and_advance(i, n, base, len, off, I, ((void)(K),0))
151 static int copyout(void __user *to, const void *from, size_t n)
153 if (should_fail_usercopy())
155 if (access_ok(to, n)) {
156 instrument_copy_to_user(to, from, n);
157 n = raw_copy_to_user(to, from, n);
162 static int copyin(void *to, const void __user *from, size_t n)
164 if (should_fail_usercopy())
166 if (access_ok(from, n)) {
167 instrument_copy_from_user(to, from, n);
168 n = raw_copy_from_user(to, from, n);
173 static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes,
176 size_t skip, copy, left, wanted;
177 const struct iovec *iov;
181 if (unlikely(bytes > i->count))
184 if (unlikely(!bytes))
190 skip = i->iov_offset;
191 buf = iov->iov_base + skip;
192 copy = min(bytes, iov->iov_len - skip);
194 if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_writeable(buf, copy)) {
195 kaddr = kmap_atomic(page);
196 from = kaddr + offset;
198 /* first chunk, usually the only one */
199 left = copyout(buf, from, copy);
205 while (unlikely(!left && bytes)) {
208 copy = min(bytes, iov->iov_len);
209 left = copyout(buf, from, copy);
215 if (likely(!bytes)) {
216 kunmap_atomic(kaddr);
219 offset = from - kaddr;
221 kunmap_atomic(kaddr);
222 copy = min(bytes, iov->iov_len - skip);
224 /* Too bad - revert to non-atomic kmap */
227 from = kaddr + offset;
228 left = copyout(buf, from, copy);
233 while (unlikely(!left && bytes)) {
236 copy = min(bytes, iov->iov_len);
237 left = copyout(buf, from, copy);
246 if (skip == iov->iov_len) {
250 i->count -= wanted - bytes;
251 i->nr_segs -= iov - i->iov;
253 i->iov_offset = skip;
254 return wanted - bytes;
257 static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t bytes,
260 size_t skip, copy, left, wanted;
261 const struct iovec *iov;
265 if (unlikely(bytes > i->count))
268 if (unlikely(!bytes))
274 skip = i->iov_offset;
275 buf = iov->iov_base + skip;
276 copy = min(bytes, iov->iov_len - skip);
278 if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_readable(buf, copy)) {
279 kaddr = kmap_atomic(page);
282 /* first chunk, usually the only one */
283 left = copyin(to, buf, copy);
289 while (unlikely(!left && bytes)) {
292 copy = min(bytes, iov->iov_len);
293 left = copyin(to, buf, copy);
299 if (likely(!bytes)) {
300 kunmap_atomic(kaddr);
305 kunmap_atomic(kaddr);
306 copy = min(bytes, iov->iov_len - skip);
308 /* Too bad - revert to non-atomic kmap */
312 left = copyin(to, buf, copy);
317 while (unlikely(!left && bytes)) {
320 copy = min(bytes, iov->iov_len);
321 left = copyin(to, buf, copy);
330 if (skip == iov->iov_len) {
334 i->count -= wanted - bytes;
335 i->nr_segs -= iov - i->iov;
337 i->iov_offset = skip;
338 return wanted - bytes;
342 static bool sanity(const struct iov_iter *i)
344 struct pipe_inode_info *pipe = i->pipe;
345 unsigned int p_head = pipe->head;
346 unsigned int p_tail = pipe->tail;
347 unsigned int p_mask = pipe->ring_size - 1;
348 unsigned int p_occupancy = pipe_occupancy(p_head, p_tail);
349 unsigned int i_head = i->head;
353 struct pipe_buffer *p;
354 if (unlikely(p_occupancy == 0))
355 goto Bad; // pipe must be non-empty
356 if (unlikely(i_head != p_head - 1))
357 goto Bad; // must be at the last buffer...
359 p = &pipe->bufs[i_head & p_mask];
360 if (unlikely(p->offset + p->len != i->iov_offset))
361 goto Bad; // ... at the end of segment
363 if (i_head != p_head)
364 goto Bad; // must be right after the last buffer
368 printk(KERN_ERR "idx = %d, offset = %zd\n", i_head, i->iov_offset);
369 printk(KERN_ERR "head = %d, tail = %d, buffers = %d\n",
370 p_head, p_tail, pipe->ring_size);
371 for (idx = 0; idx < pipe->ring_size; idx++)
372 printk(KERN_ERR "[%p %p %d %d]\n",
374 pipe->bufs[idx].page,
375 pipe->bufs[idx].offset,
376 pipe->bufs[idx].len);
381 #define sanity(i) true
384 static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes,
387 struct pipe_inode_info *pipe = i->pipe;
388 struct pipe_buffer *buf;
389 unsigned int p_tail = pipe->tail;
390 unsigned int p_mask = pipe->ring_size - 1;
391 unsigned int i_head = i->head;
394 if (unlikely(bytes > i->count))
397 if (unlikely(!bytes))
404 buf = &pipe->bufs[i_head & p_mask];
406 if (offset == off && buf->page == page) {
407 /* merge with the last one */
409 i->iov_offset += bytes;
413 buf = &pipe->bufs[i_head & p_mask];
415 if (pipe_full(i_head, p_tail, pipe->max_usage))
418 buf->ops = &page_cache_pipe_buf_ops;
422 buf->offset = offset;
425 pipe->head = i_head + 1;
426 i->iov_offset = offset + bytes;
434 * fault_in_iov_iter_readable - fault in iov iterator for reading
436 * @size: maximum length
438 * Fault in one or more iovecs of the given iov_iter, to a maximum length of
439 * @size. For each iovec, fault in each page that constitutes the iovec.
441 * Returns the number of bytes not faulted in (like copy_to_user() and
444 * Always returns 0 for non-userspace iterators.
446 size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t size)
448 if (iter_is_iovec(i)) {
449 size_t count = min(size, iov_iter_count(i));
450 const struct iovec *p;
454 for (p = i->iov, skip = i->iov_offset; count; p++, skip = 0) {
455 size_t len = min(count, p->iov_len - skip);
460 ret = fault_in_readable(p->iov_base + skip, len);
469 EXPORT_SYMBOL(fault_in_iov_iter_readable);
472 * fault_in_iov_iter_writeable - fault in iov iterator for writing
474 * @size: maximum length
476 * Faults in the iterator using get_user_pages(), i.e., without triggering
477 * hardware page faults. This is primarily useful when we already know that
478 * some or all of the pages in @i aren't in memory.
480 * Returns the number of bytes not faulted in, like copy_to_user() and
483 * Always returns 0 for non-user-space iterators.
485 size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t size)
487 if (iter_is_iovec(i)) {
488 size_t count = min(size, iov_iter_count(i));
489 const struct iovec *p;
493 for (p = i->iov, skip = i->iov_offset; count; p++, skip = 0) {
494 size_t len = min(count, p->iov_len - skip);
499 ret = fault_in_safe_writeable(p->iov_base + skip, len);
508 EXPORT_SYMBOL(fault_in_iov_iter_writeable);
510 void iov_iter_init(struct iov_iter *i, unsigned int direction,
511 const struct iovec *iov, unsigned long nr_segs,
514 WARN_ON(direction & ~(READ | WRITE));
515 *i = (struct iov_iter) {
516 .iter_type = ITER_IOVEC,
518 .data_source = direction,
525 EXPORT_SYMBOL(iov_iter_init);
527 static inline bool allocated(struct pipe_buffer *buf)
529 return buf->ops == &default_pipe_buf_ops;
532 static inline void data_start(const struct iov_iter *i,
533 unsigned int *iter_headp, size_t *offp)
535 unsigned int p_mask = i->pipe->ring_size - 1;
536 unsigned int iter_head = i->head;
537 size_t off = i->iov_offset;
539 if (off && (!allocated(&i->pipe->bufs[iter_head & p_mask]) ||
544 *iter_headp = iter_head;
548 static size_t push_pipe(struct iov_iter *i, size_t size,
549 int *iter_headp, size_t *offp)
551 struct pipe_inode_info *pipe = i->pipe;
552 unsigned int p_tail = pipe->tail;
553 unsigned int p_mask = pipe->ring_size - 1;
554 unsigned int iter_head;
558 if (unlikely(size > i->count))
564 data_start(i, &iter_head, &off);
565 *iter_headp = iter_head;
568 left -= PAGE_SIZE - off;
570 pipe->bufs[iter_head & p_mask].len += size;
573 pipe->bufs[iter_head & p_mask].len = PAGE_SIZE;
576 while (!pipe_full(iter_head, p_tail, pipe->max_usage)) {
577 struct pipe_buffer *buf = &pipe->bufs[iter_head & p_mask];
578 struct page *page = alloc_page(GFP_USER);
582 buf->ops = &default_pipe_buf_ops;
586 buf->len = min_t(ssize_t, left, PAGE_SIZE);
589 pipe->head = iter_head;
597 static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
600 struct pipe_inode_info *pipe = i->pipe;
601 unsigned int p_mask = pipe->ring_size - 1;
608 bytes = n = push_pipe(i, bytes, &i_head, &off);
612 size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
613 memcpy_to_page(pipe->bufs[i_head & p_mask].page, off, addr, chunk);
615 i->iov_offset = off + chunk;
625 static __wsum csum_and_memcpy(void *to, const void *from, size_t len,
626 __wsum sum, size_t off)
628 __wsum next = csum_partial_copy_nocheck(from, to, len);
629 return csum_block_add(sum, next, off);
632 static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes,
633 struct iov_iter *i, __wsum *sump)
635 struct pipe_inode_info *pipe = i->pipe;
636 unsigned int p_mask = pipe->ring_size - 1;
645 bytes = push_pipe(i, bytes, &i_head, &r);
647 size_t chunk = min_t(size_t, bytes, PAGE_SIZE - r);
648 char *p = kmap_local_page(pipe->bufs[i_head & p_mask].page);
649 sum = csum_and_memcpy(p + r, addr + off, chunk, sum, off);
652 i->iov_offset = r + chunk;
663 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
665 if (unlikely(iov_iter_is_pipe(i)))
666 return copy_pipe_to_iter(addr, bytes, i);
667 if (iter_is_iovec(i))
669 iterate_and_advance(i, bytes, base, len, off,
670 copyout(base, addr + off, len),
671 memcpy(base, addr + off, len)
676 EXPORT_SYMBOL(_copy_to_iter);
678 #ifdef CONFIG_ARCH_HAS_COPY_MC
679 static int copyout_mc(void __user *to, const void *from, size_t n)
681 if (access_ok(to, n)) {
682 instrument_copy_to_user(to, from, n);
683 n = copy_mc_to_user((__force void *) to, from, n);
688 static size_t copy_mc_pipe_to_iter(const void *addr, size_t bytes,
691 struct pipe_inode_info *pipe = i->pipe;
692 unsigned int p_mask = pipe->ring_size - 1;
694 unsigned int valid = pipe->head;
695 size_t n, off, xfer = 0;
700 n = push_pipe(i, bytes, &i_head, &off);
702 size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
703 char *p = kmap_local_page(pipe->bufs[i_head & p_mask].page);
705 rem = copy_mc_to_kernel(p + off, addr + xfer, chunk);
710 i->iov_offset = off + chunk;
715 pipe->bufs[i_head & p_mask].len -= rem;
716 pipe_discard_from(pipe, valid);
728 * _copy_mc_to_iter - copy to iter with source memory error exception handling
729 * @addr: source kernel address
730 * @bytes: total transfer length
731 * @i: destination iterator
733 * The pmem driver deploys this for the dax operation
734 * (dax_copy_to_iter()) for dax reads (bypass page-cache and the
735 * block-layer). Upon #MC read(2) aborts and returns EIO or the bytes
736 * successfully copied.
738 * The main differences between this and typical _copy_to_iter().
740 * * Typical tail/residue handling after a fault retries the copy
741 * byte-by-byte until the fault happens again. Re-triggering machine
742 * checks is potentially fatal so the implementation uses source
743 * alignment and poison alignment assumptions to avoid re-triggering
744 * hardware exceptions.
746 * * ITER_KVEC, ITER_PIPE, and ITER_BVEC can return short copies.
747 * Compare to copy_to_iter() where only ITER_IOVEC attempts might return
750 * Return: number of bytes copied (may be %0)
752 size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
754 if (unlikely(iov_iter_is_pipe(i)))
755 return copy_mc_pipe_to_iter(addr, bytes, i);
756 if (iter_is_iovec(i))
758 __iterate_and_advance(i, bytes, base, len, off,
759 copyout_mc(base, addr + off, len),
760 copy_mc_to_kernel(base, addr + off, len)
765 EXPORT_SYMBOL_GPL(_copy_mc_to_iter);
766 #endif /* CONFIG_ARCH_HAS_COPY_MC */
768 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
770 if (unlikely(iov_iter_is_pipe(i))) {
774 if (iter_is_iovec(i))
776 iterate_and_advance(i, bytes, base, len, off,
777 copyin(addr + off, base, len),
778 memcpy(addr + off, base, len)
783 EXPORT_SYMBOL(_copy_from_iter);
785 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
787 if (unlikely(iov_iter_is_pipe(i))) {
791 iterate_and_advance(i, bytes, base, len, off,
792 __copy_from_user_inatomic_nocache(addr + off, base, len),
793 memcpy(addr + off, base, len)
798 EXPORT_SYMBOL(_copy_from_iter_nocache);
800 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
802 * _copy_from_iter_flushcache - write destination through cpu cache
803 * @addr: destination kernel address
804 * @bytes: total transfer length
805 * @i: source iterator
807 * The pmem driver arranges for filesystem-dax to use this facility via
808 * dax_copy_from_iter() for ensuring that writes to persistent memory
809 * are flushed through the CPU cache. It is differentiated from
810 * _copy_from_iter_nocache() in that guarantees all data is flushed for
811 * all iterator types. The _copy_from_iter_nocache() only attempts to
812 * bypass the cache for the ITER_IOVEC case, and on some archs may use
813 * instructions that strand dirty-data in the cache.
815 * Return: number of bytes copied (may be %0)
817 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
819 if (unlikely(iov_iter_is_pipe(i))) {
823 iterate_and_advance(i, bytes, base, len, off,
824 __copy_from_user_flushcache(addr + off, base, len),
825 memcpy_flushcache(addr + off, base, len)
830 EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache);
833 static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
836 size_t v = n + offset;
839 * The general case needs to access the page order in order
840 * to compute the page size.
841 * However, we mostly deal with order-0 pages and thus can
842 * avoid a possible cache line miss for requests that fit all
845 if (n <= v && v <= PAGE_SIZE)
848 head = compound_head(page);
849 v += (page - head) << PAGE_SHIFT;
851 if (likely(n <= v && v <= (page_size(head))))
857 static size_t __copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
860 if (likely(iter_is_iovec(i)))
861 return copy_page_to_iter_iovec(page, offset, bytes, i);
862 if (iov_iter_is_bvec(i) || iov_iter_is_kvec(i) || iov_iter_is_xarray(i)) {
863 void *kaddr = kmap_local_page(page);
864 size_t wanted = _copy_to_iter(kaddr + offset, bytes, i);
868 if (iov_iter_is_pipe(i))
869 return copy_page_to_iter_pipe(page, offset, bytes, i);
870 if (unlikely(iov_iter_is_discard(i))) {
871 if (unlikely(i->count < bytes))
880 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
884 if (unlikely(!page_copy_sane(page, offset, bytes)))
886 page += offset / PAGE_SIZE; // first subpage
889 size_t n = __copy_page_to_iter(page, offset,
890 min(bytes, (size_t)PAGE_SIZE - offset), i);
896 if (offset == PAGE_SIZE) {
903 EXPORT_SYMBOL(copy_page_to_iter);
905 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
908 if (unlikely(!page_copy_sane(page, offset, bytes)))
910 if (likely(iter_is_iovec(i)))
911 return copy_page_from_iter_iovec(page, offset, bytes, i);
912 if (iov_iter_is_bvec(i) || iov_iter_is_kvec(i) || iov_iter_is_xarray(i)) {
913 void *kaddr = kmap_local_page(page);
914 size_t wanted = _copy_from_iter(kaddr + offset, bytes, i);
921 EXPORT_SYMBOL(copy_page_from_iter);
923 static size_t pipe_zero(size_t bytes, struct iov_iter *i)
925 struct pipe_inode_info *pipe = i->pipe;
926 unsigned int p_mask = pipe->ring_size - 1;
933 bytes = n = push_pipe(i, bytes, &i_head, &off);
938 size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
939 char *p = kmap_local_page(pipe->bufs[i_head & p_mask].page);
940 memset(p + off, 0, chunk);
943 i->iov_offset = off + chunk;
952 size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
954 if (unlikely(iov_iter_is_pipe(i)))
955 return pipe_zero(bytes, i);
956 iterate_and_advance(i, bytes, base, len, count,
957 clear_user(base, len),
963 EXPORT_SYMBOL(iov_iter_zero);
965 size_t copy_page_from_iter_atomic(struct page *page, unsigned offset, size_t bytes,
968 char *kaddr = kmap_atomic(page), *p = kaddr + offset;
969 if (unlikely(!page_copy_sane(page, offset, bytes))) {
970 kunmap_atomic(kaddr);
973 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
974 kunmap_atomic(kaddr);
978 iterate_and_advance(i, bytes, base, len, off,
979 copyin(p + off, base, len),
980 memcpy(p + off, base, len)
982 kunmap_atomic(kaddr);
985 EXPORT_SYMBOL(copy_page_from_iter_atomic);
987 static inline void pipe_truncate(struct iov_iter *i)
989 struct pipe_inode_info *pipe = i->pipe;
990 unsigned int p_tail = pipe->tail;
991 unsigned int p_head = pipe->head;
992 unsigned int p_mask = pipe->ring_size - 1;
994 if (!pipe_empty(p_head, p_tail)) {
995 struct pipe_buffer *buf;
996 unsigned int i_head = i->head;
997 size_t off = i->iov_offset;
1000 buf = &pipe->bufs[i_head & p_mask];
1001 buf->len = off - buf->offset;
1004 while (p_head != i_head) {
1006 pipe_buf_release(pipe, &pipe->bufs[p_head & p_mask]);
1009 pipe->head = p_head;
1013 static void pipe_advance(struct iov_iter *i, size_t size)
1015 struct pipe_inode_info *pipe = i->pipe;
1017 struct pipe_buffer *buf;
1018 unsigned int p_mask = pipe->ring_size - 1;
1019 unsigned int i_head = i->head;
1020 size_t off = i->iov_offset, left = size;
1022 if (off) /* make it relative to the beginning of buffer */
1023 left += off - pipe->bufs[i_head & p_mask].offset;
1025 buf = &pipe->bufs[i_head & p_mask];
1026 if (left <= buf->len)
1032 i->iov_offset = buf->offset + left;
1035 /* ... and discard everything past that point */
1039 static void iov_iter_bvec_advance(struct iov_iter *i, size_t size)
1041 struct bvec_iter bi;
1043 bi.bi_size = i->count;
1044 bi.bi_bvec_done = i->iov_offset;
1046 bvec_iter_advance(i->bvec, &bi, size);
1048 i->bvec += bi.bi_idx;
1049 i->nr_segs -= bi.bi_idx;
1050 i->count = bi.bi_size;
1051 i->iov_offset = bi.bi_bvec_done;
1054 static void iov_iter_iovec_advance(struct iov_iter *i, size_t size)
1056 const struct iovec *iov, *end;
1062 size += i->iov_offset; // from beginning of current segment
1063 for (iov = i->iov, end = iov + i->nr_segs; iov < end; iov++) {
1064 if (likely(size < iov->iov_len))
1066 size -= iov->iov_len;
1068 i->iov_offset = size;
1069 i->nr_segs -= iov - i->iov;
1073 void iov_iter_advance(struct iov_iter *i, size_t size)
1075 if (unlikely(i->count < size))
1077 if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) {
1078 /* iovec and kvec have identical layouts */
1079 iov_iter_iovec_advance(i, size);
1080 } else if (iov_iter_is_bvec(i)) {
1081 iov_iter_bvec_advance(i, size);
1082 } else if (iov_iter_is_pipe(i)) {
1083 pipe_advance(i, size);
1084 } else if (unlikely(iov_iter_is_xarray(i))) {
1085 i->iov_offset += size;
1087 } else if (iov_iter_is_discard(i)) {
1091 EXPORT_SYMBOL(iov_iter_advance);
1093 void iov_iter_revert(struct iov_iter *i, size_t unroll)
1097 if (WARN_ON(unroll > MAX_RW_COUNT))
1100 if (unlikely(iov_iter_is_pipe(i))) {
1101 struct pipe_inode_info *pipe = i->pipe;
1102 unsigned int p_mask = pipe->ring_size - 1;
1103 unsigned int i_head = i->head;
1104 size_t off = i->iov_offset;
1106 struct pipe_buffer *b = &pipe->bufs[i_head & p_mask];
1107 size_t n = off - b->offset;
1113 if (!unroll && i_head == i->start_head) {
1118 b = &pipe->bufs[i_head & p_mask];
1119 off = b->offset + b->len;
1121 i->iov_offset = off;
1126 if (unlikely(iov_iter_is_discard(i)))
1128 if (unroll <= i->iov_offset) {
1129 i->iov_offset -= unroll;
1132 unroll -= i->iov_offset;
1133 if (iov_iter_is_xarray(i)) {
1134 BUG(); /* We should never go beyond the start of the specified
1135 * range since we might then be straying into pages that
1138 } else if (iov_iter_is_bvec(i)) {
1139 const struct bio_vec *bvec = i->bvec;
1141 size_t n = (--bvec)->bv_len;
1145 i->iov_offset = n - unroll;
1150 } else { /* same logics for iovec and kvec */
1151 const struct iovec *iov = i->iov;
1153 size_t n = (--iov)->iov_len;
1157 i->iov_offset = n - unroll;
1164 EXPORT_SYMBOL(iov_iter_revert);
1167 * Return the count of just the current iov_iter segment.
1169 size_t iov_iter_single_seg_count(const struct iov_iter *i)
1171 if (i->nr_segs > 1) {
1172 if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i)))
1173 return min(i->count, i->iov->iov_len - i->iov_offset);
1174 if (iov_iter_is_bvec(i))
1175 return min(i->count, i->bvec->bv_len - i->iov_offset);
1179 EXPORT_SYMBOL(iov_iter_single_seg_count);
1181 void iov_iter_kvec(struct iov_iter *i, unsigned int direction,
1182 const struct kvec *kvec, unsigned long nr_segs,
1185 WARN_ON(direction & ~(READ | WRITE));
1186 *i = (struct iov_iter){
1187 .iter_type = ITER_KVEC,
1188 .data_source = direction,
1195 EXPORT_SYMBOL(iov_iter_kvec);
1197 void iov_iter_bvec(struct iov_iter *i, unsigned int direction,
1198 const struct bio_vec *bvec, unsigned long nr_segs,
1201 WARN_ON(direction & ~(READ | WRITE));
1202 *i = (struct iov_iter){
1203 .iter_type = ITER_BVEC,
1204 .data_source = direction,
1211 EXPORT_SYMBOL(iov_iter_bvec);
1213 void iov_iter_pipe(struct iov_iter *i, unsigned int direction,
1214 struct pipe_inode_info *pipe,
1217 BUG_ON(direction != READ);
1218 WARN_ON(pipe_full(pipe->head, pipe->tail, pipe->ring_size));
1219 *i = (struct iov_iter){
1220 .iter_type = ITER_PIPE,
1221 .data_source = false,
1224 .start_head = pipe->head,
1229 EXPORT_SYMBOL(iov_iter_pipe);
1232 * iov_iter_xarray - Initialise an I/O iterator to use the pages in an xarray
1233 * @i: The iterator to initialise.
1234 * @direction: The direction of the transfer.
1235 * @xarray: The xarray to access.
1236 * @start: The start file position.
1237 * @count: The size of the I/O buffer in bytes.
1239 * Set up an I/O iterator to either draw data out of the pages attached to an
1240 * inode or to inject data into those pages. The pages *must* be prevented
1241 * from evaporation, either by taking a ref on them or locking them by the
1244 void iov_iter_xarray(struct iov_iter *i, unsigned int direction,
1245 struct xarray *xarray, loff_t start, size_t count)
1247 BUG_ON(direction & ~1);
1248 *i = (struct iov_iter) {
1249 .iter_type = ITER_XARRAY,
1250 .data_source = direction,
1252 .xarray_start = start,
1257 EXPORT_SYMBOL(iov_iter_xarray);
1260 * iov_iter_discard - Initialise an I/O iterator that discards data
1261 * @i: The iterator to initialise.
1262 * @direction: The direction of the transfer.
1263 * @count: The size of the I/O buffer in bytes.
1265 * Set up an I/O iterator that just discards everything that's written to it.
1266 * It's only available as a READ iterator.
1268 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count)
1270 BUG_ON(direction != READ);
1271 *i = (struct iov_iter){
1272 .iter_type = ITER_DISCARD,
1273 .data_source = false,
1278 EXPORT_SYMBOL(iov_iter_discard);
1280 static unsigned long iov_iter_alignment_iovec(const struct iov_iter *i)
1282 unsigned long res = 0;
1283 size_t size = i->count;
1284 size_t skip = i->iov_offset;
1287 for (k = 0; k < i->nr_segs; k++, skip = 0) {
1288 size_t len = i->iov[k].iov_len - skip;
1290 res |= (unsigned long)i->iov[k].iov_base + skip;
1302 static unsigned long iov_iter_alignment_bvec(const struct iov_iter *i)
1305 size_t size = i->count;
1306 unsigned skip = i->iov_offset;
1309 for (k = 0; k < i->nr_segs; k++, skip = 0) {
1310 size_t len = i->bvec[k].bv_len - skip;
1311 res |= (unsigned long)i->bvec[k].bv_offset + skip;
1322 unsigned long iov_iter_alignment(const struct iov_iter *i)
1324 /* iovec and kvec have identical layouts */
1325 if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i)))
1326 return iov_iter_alignment_iovec(i);
1328 if (iov_iter_is_bvec(i))
1329 return iov_iter_alignment_bvec(i);
1331 if (iov_iter_is_pipe(i)) {
1332 unsigned int p_mask = i->pipe->ring_size - 1;
1333 size_t size = i->count;
1335 if (size && i->iov_offset && allocated(&i->pipe->bufs[i->head & p_mask]))
1336 return size | i->iov_offset;
1340 if (iov_iter_is_xarray(i))
1341 return (i->xarray_start + i->iov_offset) | i->count;
1345 EXPORT_SYMBOL(iov_iter_alignment);
1347 unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
1349 unsigned long res = 0;
1350 unsigned long v = 0;
1351 size_t size = i->count;
1354 if (WARN_ON(!iter_is_iovec(i)))
1357 for (k = 0; k < i->nr_segs; k++) {
1358 if (i->iov[k].iov_len) {
1359 unsigned long base = (unsigned long)i->iov[k].iov_base;
1360 if (v) // if not the first one
1361 res |= base | v; // this start | previous end
1362 v = base + i->iov[k].iov_len;
1363 if (size <= i->iov[k].iov_len)
1365 size -= i->iov[k].iov_len;
1370 EXPORT_SYMBOL(iov_iter_gap_alignment);
1372 static inline ssize_t __pipe_get_pages(struct iov_iter *i,
1374 struct page **pages,
1378 struct pipe_inode_info *pipe = i->pipe;
1379 unsigned int p_mask = pipe->ring_size - 1;
1380 ssize_t n = push_pipe(i, maxsize, &iter_head, start);
1387 get_page(*pages++ = pipe->bufs[iter_head & p_mask].page);
1395 static ssize_t pipe_get_pages(struct iov_iter *i,
1396 struct page **pages, size_t maxsize, unsigned maxpages,
1399 unsigned int iter_head, npages;
1405 data_start(i, &iter_head, start);
1406 /* Amount of free space: some of this one + all after this one */
1407 npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
1408 capacity = min(npages, maxpages) * PAGE_SIZE - *start;
1410 return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, start);
1413 static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa,
1414 pgoff_t index, unsigned int nr_pages)
1416 XA_STATE(xas, xa, index);
1418 unsigned int ret = 0;
1421 for (page = xas_load(&xas); page; page = xas_next(&xas)) {
1422 if (xas_retry(&xas, page))
1425 /* Has the page moved or been split? */
1426 if (unlikely(page != xas_reload(&xas))) {
1431 pages[ret] = find_subpage(page, xas.xa_index);
1432 get_page(pages[ret]);
1433 if (++ret == nr_pages)
1440 static ssize_t iter_xarray_get_pages(struct iov_iter *i,
1441 struct page **pages, size_t maxsize,
1442 unsigned maxpages, size_t *_start_offset)
1444 unsigned nr, offset;
1445 pgoff_t index, count;
1446 size_t size = maxsize;
1449 if (!size || !maxpages)
1452 pos = i->xarray_start + i->iov_offset;
1453 index = pos >> PAGE_SHIFT;
1454 offset = pos & ~PAGE_MASK;
1455 *_start_offset = offset;
1458 if (size > PAGE_SIZE - offset) {
1459 size -= PAGE_SIZE - offset;
1460 count += size >> PAGE_SHIFT;
1466 if (count > maxpages)
1469 nr = iter_xarray_populate_pages(pages, i->xarray, index, count);
1473 return min_t(size_t, nr * PAGE_SIZE - offset, maxsize);
1476 /* must be done on non-empty ITER_IOVEC one */
1477 static unsigned long first_iovec_segment(const struct iov_iter *i,
1478 size_t *size, size_t *start,
1479 size_t maxsize, unsigned maxpages)
1484 for (k = 0, skip = i->iov_offset; k < i->nr_segs; k++, skip = 0) {
1485 unsigned long addr = (unsigned long)i->iov[k].iov_base + skip;
1486 size_t len = i->iov[k].iov_len - skip;
1492 len += (*start = addr % PAGE_SIZE);
1493 if (len > maxpages * PAGE_SIZE)
1494 len = maxpages * PAGE_SIZE;
1496 return addr & PAGE_MASK;
1498 BUG(); // if it had been empty, we wouldn't get called
1501 /* must be done on non-empty ITER_BVEC one */
1502 static struct page *first_bvec_segment(const struct iov_iter *i,
1503 size_t *size, size_t *start,
1504 size_t maxsize, unsigned maxpages)
1507 size_t skip = i->iov_offset, len;
1509 len = i->bvec->bv_len - skip;
1512 skip += i->bvec->bv_offset;
1513 page = i->bvec->bv_page + skip / PAGE_SIZE;
1514 len += (*start = skip % PAGE_SIZE);
1515 if (len > maxpages * PAGE_SIZE)
1516 len = maxpages * PAGE_SIZE;
1521 ssize_t iov_iter_get_pages(struct iov_iter *i,
1522 struct page **pages, size_t maxsize, unsigned maxpages,
1528 if (maxsize > i->count)
1533 if (likely(iter_is_iovec(i))) {
1534 unsigned int gup_flags = 0;
1537 if (iov_iter_rw(i) != WRITE)
1538 gup_flags |= FOLL_WRITE;
1540 gup_flags |= FOLL_NOFAULT;
1542 addr = first_iovec_segment(i, &len, start, maxsize, maxpages);
1543 n = DIV_ROUND_UP(len, PAGE_SIZE);
1544 res = get_user_pages_fast(addr, n, gup_flags, pages);
1545 if (unlikely(res <= 0))
1547 return (res == n ? len : res * PAGE_SIZE) - *start;
1549 if (iov_iter_is_bvec(i)) {
1552 page = first_bvec_segment(i, &len, start, maxsize, maxpages);
1553 n = DIV_ROUND_UP(len, PAGE_SIZE);
1555 get_page(*pages++ = page++);
1556 return len - *start;
1558 if (iov_iter_is_pipe(i))
1559 return pipe_get_pages(i, pages, maxsize, maxpages, start);
1560 if (iov_iter_is_xarray(i))
1561 return iter_xarray_get_pages(i, pages, maxsize, maxpages, start);
1564 EXPORT_SYMBOL(iov_iter_get_pages);
1566 static struct page **get_pages_array(size_t n)
1568 return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL);
1571 static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
1572 struct page ***pages, size_t maxsize,
1576 unsigned int iter_head, npages;
1582 data_start(i, &iter_head, start);
1583 /* Amount of free space: some of this one + all after this one */
1584 npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
1585 n = npages * PAGE_SIZE - *start;
1589 npages = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
1590 p = get_pages_array(npages);
1593 n = __pipe_get_pages(i, maxsize, p, iter_head, start);
1601 static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i,
1602 struct page ***pages, size_t maxsize,
1603 size_t *_start_offset)
1606 unsigned nr, offset;
1607 pgoff_t index, count;
1608 size_t size = maxsize;
1614 pos = i->xarray_start + i->iov_offset;
1615 index = pos >> PAGE_SHIFT;
1616 offset = pos & ~PAGE_MASK;
1617 *_start_offset = offset;
1620 if (size > PAGE_SIZE - offset) {
1621 size -= PAGE_SIZE - offset;
1622 count += size >> PAGE_SHIFT;
1628 p = get_pages_array(count);
1633 nr = iter_xarray_populate_pages(p, i->xarray, index, count);
1637 return min_t(size_t, nr * PAGE_SIZE - offset, maxsize);
1640 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
1641 struct page ***pages, size_t maxsize,
1648 if (maxsize > i->count)
1653 if (likely(iter_is_iovec(i))) {
1654 unsigned int gup_flags = 0;
1657 if (iov_iter_rw(i) != WRITE)
1658 gup_flags |= FOLL_WRITE;
1660 gup_flags |= FOLL_NOFAULT;
1662 addr = first_iovec_segment(i, &len, start, maxsize, ~0U);
1663 n = DIV_ROUND_UP(len, PAGE_SIZE);
1664 p = get_pages_array(n);
1667 res = get_user_pages_fast(addr, n, gup_flags, p);
1668 if (unlikely(res <= 0)) {
1674 return (res == n ? len : res * PAGE_SIZE) - *start;
1676 if (iov_iter_is_bvec(i)) {
1679 page = first_bvec_segment(i, &len, start, maxsize, ~0U);
1680 n = DIV_ROUND_UP(len, PAGE_SIZE);
1681 *pages = p = get_pages_array(n);
1685 get_page(*p++ = page++);
1686 return len - *start;
1688 if (iov_iter_is_pipe(i))
1689 return pipe_get_pages_alloc(i, pages, maxsize, start);
1690 if (iov_iter_is_xarray(i))
1691 return iter_xarray_get_pages_alloc(i, pages, maxsize, start);
1694 EXPORT_SYMBOL(iov_iter_get_pages_alloc);
1696 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
1701 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
1705 iterate_and_advance(i, bytes, base, len, off, ({
1706 next = csum_and_copy_from_user(base, addr + off, len);
1707 sum = csum_block_add(sum, next, off);
1710 sum = csum_and_memcpy(addr + off, base, len, sum, off);
1716 EXPORT_SYMBOL(csum_and_copy_from_iter);
1718 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate,
1721 struct csum_state *csstate = _csstate;
1724 if (unlikely(iov_iter_is_discard(i))) {
1725 WARN_ON(1); /* for now */
1729 sum = csum_shift(csstate->csum, csstate->off);
1730 if (unlikely(iov_iter_is_pipe(i)))
1731 bytes = csum_and_copy_to_pipe_iter(addr, bytes, i, &sum);
1732 else iterate_and_advance(i, bytes, base, len, off, ({
1733 next = csum_and_copy_to_user(addr + off, base, len);
1734 sum = csum_block_add(sum, next, off);
1737 sum = csum_and_memcpy(base, addr + off, len, sum, off);
1740 csstate->csum = csum_shift(sum, csstate->off);
1741 csstate->off += bytes;
1744 EXPORT_SYMBOL(csum_and_copy_to_iter);
1746 size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
1749 #ifdef CONFIG_CRYPTO_HASH
1750 struct ahash_request *hash = hashp;
1751 struct scatterlist sg;
1754 copied = copy_to_iter(addr, bytes, i);
1755 sg_init_one(&sg, addr, copied);
1756 ahash_request_set_crypt(hash, &sg, NULL, copied);
1757 crypto_ahash_update(hash);
1763 EXPORT_SYMBOL(hash_and_copy_to_iter);
1765 static int iov_npages(const struct iov_iter *i, int maxpages)
1767 size_t skip = i->iov_offset, size = i->count;
1768 const struct iovec *p;
1771 for (p = i->iov; size; skip = 0, p++) {
1772 unsigned offs = offset_in_page(p->iov_base + skip);
1773 size_t len = min(p->iov_len - skip, size);
1777 npages += DIV_ROUND_UP(offs + len, PAGE_SIZE);
1778 if (unlikely(npages > maxpages))
1785 static int bvec_npages(const struct iov_iter *i, int maxpages)
1787 size_t skip = i->iov_offset, size = i->count;
1788 const struct bio_vec *p;
1791 for (p = i->bvec; size; skip = 0, p++) {
1792 unsigned offs = (p->bv_offset + skip) % PAGE_SIZE;
1793 size_t len = min(p->bv_len - skip, size);
1796 npages += DIV_ROUND_UP(offs + len, PAGE_SIZE);
1797 if (unlikely(npages > maxpages))
1803 int iov_iter_npages(const struct iov_iter *i, int maxpages)
1805 if (unlikely(!i->count))
1807 /* iovec and kvec have identical layouts */
1808 if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i)))
1809 return iov_npages(i, maxpages);
1810 if (iov_iter_is_bvec(i))
1811 return bvec_npages(i, maxpages);
1812 if (iov_iter_is_pipe(i)) {
1813 unsigned int iter_head;
1820 data_start(i, &iter_head, &off);
1821 /* some of this one + all after this one */
1822 npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
1823 return min(npages, maxpages);
1825 if (iov_iter_is_xarray(i)) {
1826 unsigned offset = (i->xarray_start + i->iov_offset) % PAGE_SIZE;
1827 int npages = DIV_ROUND_UP(offset + i->count, PAGE_SIZE);
1828 return min(npages, maxpages);
1832 EXPORT_SYMBOL(iov_iter_npages);
1834 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
1837 if (unlikely(iov_iter_is_pipe(new))) {
1841 if (unlikely(iov_iter_is_discard(new) || iov_iter_is_xarray(new)))
1843 if (iov_iter_is_bvec(new))
1844 return new->bvec = kmemdup(new->bvec,
1845 new->nr_segs * sizeof(struct bio_vec),
1848 /* iovec and kvec have identical layout */
1849 return new->iov = kmemdup(new->iov,
1850 new->nr_segs * sizeof(struct iovec),
1853 EXPORT_SYMBOL(dup_iter);
1855 static int copy_compat_iovec_from_user(struct iovec *iov,
1856 const struct iovec __user *uvec, unsigned long nr_segs)
1858 const struct compat_iovec __user *uiov =
1859 (const struct compat_iovec __user *)uvec;
1860 int ret = -EFAULT, i;
1862 if (!user_access_begin(uiov, nr_segs * sizeof(*uiov)))
1865 for (i = 0; i < nr_segs; i++) {
1869 unsafe_get_user(len, &uiov[i].iov_len, uaccess_end);
1870 unsafe_get_user(buf, &uiov[i].iov_base, uaccess_end);
1872 /* check for compat_size_t not fitting in compat_ssize_t .. */
1877 iov[i].iov_base = compat_ptr(buf);
1878 iov[i].iov_len = len;
1887 static int copy_iovec_from_user(struct iovec *iov,
1888 const struct iovec __user *uvec, unsigned long nr_segs)
1892 if (copy_from_user(iov, uvec, nr_segs * sizeof(*uvec)))
1894 for (seg = 0; seg < nr_segs; seg++) {
1895 if ((ssize_t)iov[seg].iov_len < 0)
1902 struct iovec *iovec_from_user(const struct iovec __user *uvec,
1903 unsigned long nr_segs, unsigned long fast_segs,
1904 struct iovec *fast_iov, bool compat)
1906 struct iovec *iov = fast_iov;
1910 * SuS says "The readv() function *may* fail if the iovcnt argument was
1911 * less than or equal to 0, or greater than {IOV_MAX}. Linux has
1912 * traditionally returned zero for zero segments, so...
1916 if (nr_segs > UIO_MAXIOV)
1917 return ERR_PTR(-EINVAL);
1918 if (nr_segs > fast_segs) {
1919 iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL);
1921 return ERR_PTR(-ENOMEM);
1925 ret = copy_compat_iovec_from_user(iov, uvec, nr_segs);
1927 ret = copy_iovec_from_user(iov, uvec, nr_segs);
1929 if (iov != fast_iov)
1931 return ERR_PTR(ret);
1937 ssize_t __import_iovec(int type, const struct iovec __user *uvec,
1938 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
1939 struct iov_iter *i, bool compat)
1941 ssize_t total_len = 0;
1945 iov = iovec_from_user(uvec, nr_segs, fast_segs, *iovp, compat);
1948 return PTR_ERR(iov);
1952 * According to the Single Unix Specification we should return EINVAL if
1953 * an element length is < 0 when cast to ssize_t or if the total length
1954 * would overflow the ssize_t return value of the system call.
1956 * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the
1959 for (seg = 0; seg < nr_segs; seg++) {
1960 ssize_t len = (ssize_t)iov[seg].iov_len;
1962 if (!access_ok(iov[seg].iov_base, len)) {
1969 if (len > MAX_RW_COUNT - total_len) {
1970 len = MAX_RW_COUNT - total_len;
1971 iov[seg].iov_len = len;
1976 iov_iter_init(i, type, iov, nr_segs, total_len);
1985 * import_iovec() - Copy an array of &struct iovec from userspace
1986 * into the kernel, check that it is valid, and initialize a new
1987 * &struct iov_iter iterator to access it.
1989 * @type: One of %READ or %WRITE.
1990 * @uvec: Pointer to the userspace array.
1991 * @nr_segs: Number of elements in userspace array.
1992 * @fast_segs: Number of elements in @iov.
1993 * @iovp: (input and output parameter) Pointer to pointer to (usually small
1994 * on-stack) kernel array.
1995 * @i: Pointer to iterator that will be initialized on success.
1997 * If the array pointed to by *@iov is large enough to hold all @nr_segs,
1998 * then this function places %NULL in *@iov on return. Otherwise, a new
1999 * array will be allocated and the result placed in *@iov. This means that
2000 * the caller may call kfree() on *@iov regardless of whether the small
2001 * on-stack array was used or not (and regardless of whether this function
2002 * returns an error or not).
2004 * Return: Negative error code on error, bytes imported on success
2006 ssize_t import_iovec(int type, const struct iovec __user *uvec,
2007 unsigned nr_segs, unsigned fast_segs,
2008 struct iovec **iovp, struct iov_iter *i)
2010 return __import_iovec(type, uvec, nr_segs, fast_segs, iovp, i,
2011 in_compat_syscall());
2013 EXPORT_SYMBOL(import_iovec);
2015 int import_single_range(int rw, void __user *buf, size_t len,
2016 struct iovec *iov, struct iov_iter *i)
2018 if (len > MAX_RW_COUNT)
2020 if (unlikely(!access_ok(buf, len)))
2023 iov->iov_base = buf;
2025 iov_iter_init(i, rw, iov, 1, len);
2028 EXPORT_SYMBOL(import_single_range);
2031 * iov_iter_restore() - Restore a &struct iov_iter to the same state as when
2032 * iov_iter_save_state() was called.
2034 * @i: &struct iov_iter to restore
2035 * @state: state to restore from
2037 * Used after iov_iter_save_state() to bring restore @i, if operations may
2040 * Note: only works on ITER_IOVEC, ITER_BVEC, and ITER_KVEC
2042 void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state)
2044 if (WARN_ON_ONCE(!iov_iter_is_bvec(i) && !iter_is_iovec(i)) &&
2045 !iov_iter_is_kvec(i))
2047 i->iov_offset = state->iov_offset;
2048 i->count = state->count;
2050 * For the *vec iters, nr_segs + iov is constant - if we increment
2051 * the vec, then we also decrement the nr_segs count. Hence we don't
2052 * need to track both of these, just one is enough and we can deduct
2053 * the other from that. ITER_KVEC and ITER_IOVEC are the same struct
2054 * size, so we can just increment the iov pointer as they are unionzed.
2055 * ITER_BVEC _may_ be the same size on some archs, but on others it is
2056 * not. Be safe and handle it separately.
2058 BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec));
2059 if (iov_iter_is_bvec(i))
2060 i->bvec -= state->nr_segs - i->nr_segs;
2062 i->iov -= state->nr_segs - i->nr_segs;
2063 i->nr_segs = state->nr_segs;