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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Berkeley style UIO structures - Alan Cox 1994.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8 */
David Howells607ca462012-10-13 10:46:48 +01009#ifndef __LINUX_UIO_H
10#define __LINUX_UIO_H
Linus Torvalds1da177e2005-04-16 15:20:36 -070011
Kent Overstreet92236872013-11-27 16:29:46 -080012#include <linux/kernel.h>
David Howells607ca462012-10-13 10:46:48 +010013#include <uapi/linux/uio.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014
Kent Overstreet92236872013-11-27 16:29:46 -080015struct page;
Jiri Slaby812ed032009-07-29 15:04:19 -070016
17struct kvec {
18 void *iov_base; /* and that should *never* hold a userland pointer */
19 size_t iov_len;
20};
21
Al Viro62a80672014-04-04 23:12:29 -040022enum {
23 ITER_IOVEC = 0,
24 ITER_KVEC = 2,
25 ITER_BVEC = 4,
26};
27
Kent Overstreet92236872013-11-27 16:29:46 -080028struct iov_iter {
Al Viro71d8e532014-03-05 19:28:09 -050029 int type;
Kent Overstreet92236872013-11-27 16:29:46 -080030 size_t iov_offset;
31 size_t count;
Al Viro62a80672014-04-04 23:12:29 -040032 union {
33 const struct iovec *iov;
34 const struct bio_vec *bvec;
35 };
36 unsigned long nr_segs;
Kent Overstreet92236872013-11-27 16:29:46 -080037};
38
Linus Torvalds1da177e2005-04-16 15:20:36 -070039/*
40 * Total number of bytes covered by an iovec.
41 *
42 * NOTE that it is not safe to use this function until all the iovec's
43 * segment lengths have been validated. Because the individual lengths can
44 * overflow a size_t when added together.
45 */
46static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
47{
48 unsigned long seg;
49 size_t ret = 0;
50
51 for (seg = 0; seg < nr_segs; seg++)
52 ret += iov[seg].iov_len;
53 return ret;
54}
55
Kent Overstreet92236872013-11-27 16:29:46 -080056static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
57{
58 return (struct iovec) {
59 .iov_base = iter->iov->iov_base + iter->iov_offset,
60 .iov_len = min(iter->count,
61 iter->iov->iov_len - iter->iov_offset),
62 };
63}
64
65#define iov_for_each(iov, iter, start) \
Al Viro62a80672014-04-04 23:12:29 -040066 if (!((start).type & ITER_BVEC)) \
Kent Overstreet92236872013-11-27 16:29:46 -080067 for (iter = (start); \
68 (iter).count && \
69 ((iov = iov_iter_iovec(&(iter))), 1); \
70 iov_iter_advance(&(iter), (iov).iov_len))
71
Linus Torvalds1da177e2005-04-16 15:20:36 -070072unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
Rusty Russelld2f83e92013-05-17 09:05:21 +093073
Kent Overstreet92236872013-11-27 16:29:46 -080074size_t iov_iter_copy_from_user_atomic(struct page *page,
75 struct iov_iter *i, unsigned long offset, size_t bytes);
Kent Overstreet92236872013-11-27 16:29:46 -080076void iov_iter_advance(struct iov_iter *i, size_t bytes);
77int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
78size_t iov_iter_single_seg_count(const struct iov_iter *i);
Al Viro6e58e792014-02-03 17:07:03 -050079size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
80 struct iov_iter *i);
Al Virof0d1bec2014-04-03 15:05:18 -040081size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
82 struct iov_iter *i);
Al Viro886a3912014-03-05 13:50:45 -050083unsigned long iov_iter_alignment(const struct iov_iter *i);
Al Viro71d8e532014-03-05 19:28:09 -050084void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
85 unsigned long nr_segs, size_t count);
Al Viro7b2c99d2014-03-15 04:05:57 -040086ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
Al Viroc7f38882014-06-18 20:34:33 -040087 unsigned maxpages, size_t *start);
Al Viro91f79c42014-03-21 04:58:33 -040088ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
89 size_t maxsize, size_t *start);
Al Virof67da302014-03-19 01:16:16 -040090int iov_iter_npages(const struct iov_iter *i, int maxpages);
Kent Overstreet92236872013-11-27 16:29:46 -080091
92static inline size_t iov_iter_count(struct iov_iter *i)
93{
94 return i->count;
95}
96
Al Viro0b86dbf2014-06-23 08:44:40 +010097/*
98 * Cap the iov_iter by given limit; note that the second argument is
99 * *not* the new size - it's upper limit for such. Passing it a value
100 * greater than the amount of data in iov_iter is fine - it'll just do
101 * nothing in that case.
102 */
103static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
Al Viro0c949332014-03-22 06:51:37 -0400104{
Al Viro0b86dbf2014-06-23 08:44:40 +0100105 /*
106 * count doesn't have to fit in size_t - comparison extends both
107 * operands to u64 here and any value that would be truncated by
108 * conversion in assignement is by definition greater than all
109 * values of size_t, including old i->count.
110 */
Al Viro0c949332014-03-22 06:51:37 -0400111 if (i->count > count)
112 i->count = count;
113}
114
Al Virob42b15f2014-04-04 12:15:19 -0400115/*
116 * reexpand a previously truncated iterator; count must be no more than how much
117 * we had shrunk it.
118 */
119static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
120{
121 i->count = count;
122}
123
Rusty Russelld2f83e92013-05-17 09:05:21 +0930124int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
125int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len);
Michael S. Tsirkinac5ccdb2014-06-19 21:22:56 +0300126int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov,
127 int offset, int len);
128int memcpy_toiovecend(const struct iovec *v, unsigned char *kdata,
129 int offset, int len);
Al Viro886a3912014-03-05 13:50:45 -0500130
Jiri Slaby812ed032009-07-29 15:04:19 -0700131#endif