1/*
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 */
9#ifndef __LINUX_UIO_H
10#define __LINUX_UIO_H
11
12#include <linux/kernel.h>
13#include <uapi/linux/uio.h>
14
15struct page;
16
17struct kvec {
18	void *iov_base; /* and that should *never* hold a userland pointer */
19	size_t iov_len;
20};
21
22enum {
23	ITER_IOVEC = 0,
24	ITER_KVEC = 2,
25	ITER_BVEC = 4,
26};
27
28struct iov_iter {
29	int type;
30	size_t iov_offset;
31	size_t count;
32	union {
33		const struct iovec *iov;
34		const struct kvec *kvec;
35		const struct bio_vec *bvec;
36	};
37	unsigned long nr_segs;
38};
39
40/*
41 * Total number of bytes covered by an iovec.
42 *
43 * NOTE that it is not safe to use this function until all the iovec's
44 * segment lengths have been validated.  Because the individual lengths can
45 * overflow a size_t when added together.
46 */
47static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
48{
49	unsigned long seg;
50	size_t ret = 0;
51
52	for (seg = 0; seg < nr_segs; seg++)
53		ret += iov[seg].iov_len;
54	return ret;
55}
56
57static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
58{
59	return (struct iovec) {
60		.iov_base = iter->iov->iov_base + iter->iov_offset,
61		.iov_len = min(iter->count,
62			       iter->iov->iov_len - iter->iov_offset),
63	};
64}
65
66#define iov_for_each(iov, iter, start)				\
67	if (!((start).type & ITER_BVEC))			\
68	for (iter = (start);					\
69	     (iter).count &&					\
70	     ((iov = iov_iter_iovec(&(iter))), 1);		\
71	     iov_iter_advance(&(iter), (iov).iov_len))
72
73unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
74
75size_t iov_iter_copy_from_user_atomic(struct page *page,
76		struct iov_iter *i, unsigned long offset, size_t bytes);
77void iov_iter_advance(struct iov_iter *i, size_t bytes);
78int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
79int iov_iter_fault_in_multipages_readable(struct iov_iter *i, size_t bytes);
80size_t iov_iter_single_seg_count(const struct iov_iter *i);
81size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
82			 struct iov_iter *i);
83size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
84			 struct iov_iter *i);
85size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i);
86size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
87size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
88size_t iov_iter_zero(size_t bytes, struct iov_iter *);
89unsigned long iov_iter_alignment(const struct iov_iter *i);
90void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
91			unsigned long nr_segs, size_t count);
92void iov_iter_kvec(struct iov_iter *i, int direction, const struct kvec *kvec,
93			unsigned long nr_segs, size_t count);
94void iov_iter_bvec(struct iov_iter *i, int direction, const struct bio_vec *bvec,
95			unsigned long nr_segs, size_t count);
96ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
97			size_t maxsize, unsigned maxpages, size_t *start);
98ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
99			size_t maxsize, size_t *start);
100int iov_iter_npages(const struct iov_iter *i, int maxpages);
101
102const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
103
104static inline size_t iov_iter_count(struct iov_iter *i)
105{
106	return i->count;
107}
108
109static inline bool iter_is_iovec(struct iov_iter *i)
110{
111	return !(i->type & (ITER_BVEC | ITER_KVEC));
112}
113
114/*
115 * Get one of READ or WRITE out of iter->type without any other flags OR'd in
116 * with it.
117 *
118 * The ?: is just for type safety.
119 */
120#define iov_iter_rw(i) ((0 ? (struct iov_iter *)0 : (i))->type & RW_MASK)
121
122/*
123 * Cap the iov_iter by given limit; note that the second argument is
124 * *not* the new size - it's upper limit for such.  Passing it a value
125 * greater than the amount of data in iov_iter is fine - it'll just do
126 * nothing in that case.
127 */
128static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
129{
130	/*
131	 * count doesn't have to fit in size_t - comparison extends both
132	 * operands to u64 here and any value that would be truncated by
133	 * conversion in assignement is by definition greater than all
134	 * values of size_t, including old i->count.
135	 */
136	if (i->count > count)
137		i->count = count;
138}
139
140/*
141 * reexpand a previously truncated iterator; count must be no more than how much
142 * we had shrunk it.
143 */
144static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
145{
146	i->count = count;
147}
148size_t csum_and_copy_to_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
149size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
150
151int import_iovec(int type, const struct iovec __user * uvector,
152		 unsigned nr_segs, unsigned fast_segs,
153		 struct iovec **iov, struct iov_iter *i);
154
155#ifdef CONFIG_COMPAT
156struct compat_iovec;
157int compat_import_iovec(int type, const struct compat_iovec __user * uvector,
158		 unsigned nr_segs, unsigned fast_segs,
159		 struct iovec **iov, struct iov_iter *i);
160#endif
161
162int import_single_range(int type, void __user *buf, size_t len,
163		 struct iovec *iov, struct iov_iter *i);
164
165#endif
166