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TOMOYO Linux Cross Reference
Linux/include/linux/uio.h

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  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 <linux/thread_info.h>
 14 #include <uapi/linux/uio.h>
 15 
 16 struct page;
 17 struct pipe_inode_info;
 18 
 19 struct kvec {
 20         void *iov_base; /* and that should *never* hold a userland pointer */
 21         size_t iov_len;
 22 };
 23 
 24 enum {
 25         ITER_IOVEC = 0,
 26         ITER_KVEC = 2,
 27         ITER_BVEC = 4,
 28         ITER_PIPE = 8,
 29 };
 30 
 31 struct iov_iter {
 32         int type;
 33         size_t iov_offset;
 34         size_t count;
 35         union {
 36                 const struct iovec *iov;
 37                 const struct kvec *kvec;
 38                 const struct bio_vec *bvec;
 39                 struct pipe_inode_info *pipe;
 40         };
 41         union {
 42                 unsigned long nr_segs;
 43                 struct {
 44                         int idx;
 45                         int start_idx;
 46                 };
 47         };
 48 };
 49 
 50 /*
 51  * Total number of bytes covered by an iovec.
 52  *
 53  * NOTE that it is not safe to use this function until all the iovec's
 54  * segment lengths have been validated.  Because the individual lengths can
 55  * overflow a size_t when added together.
 56  */
 57 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
 58 {
 59         unsigned long seg;
 60         size_t ret = 0;
 61 
 62         for (seg = 0; seg < nr_segs; seg++)
 63                 ret += iov[seg].iov_len;
 64         return ret;
 65 }
 66 
 67 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
 68 {
 69         return (struct iovec) {
 70                 .iov_base = iter->iov->iov_base + iter->iov_offset,
 71                 .iov_len = min(iter->count,
 72                                iter->iov->iov_len - iter->iov_offset),
 73         };
 74 }
 75 
 76 #define iov_for_each(iov, iter, start)                          \
 77         if (!((start).type & (ITER_BVEC | ITER_PIPE)))          \
 78         for (iter = (start);                                    \
 79              (iter).count &&                                    \
 80              ((iov = iov_iter_iovec(&(iter))), 1);              \
 81              iov_iter_advance(&(iter), (iov).iov_len))
 82 
 83 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
 84 
 85 size_t iov_iter_copy_from_user_atomic(struct page *page,
 86                 struct iov_iter *i, unsigned long offset, size_t bytes);
 87 void iov_iter_advance(struct iov_iter *i, size_t bytes);
 88 void iov_iter_revert(struct iov_iter *i, size_t bytes);
 89 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
 90 size_t iov_iter_single_seg_count(const struct iov_iter *i);
 91 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
 92                          struct iov_iter *i);
 93 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
 94                          struct iov_iter *i);
 95 
 96 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
 97 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
 98 bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i);
 99 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
100 bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i);
101 
102 static __always_inline __must_check
103 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
104 {
105         if (unlikely(!check_copy_size(addr, bytes, true)))
106                 return 0;
107         else
108                 return _copy_to_iter(addr, bytes, i);
109 }
110 
111 static __always_inline __must_check
112 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
113 {
114         if (unlikely(!check_copy_size(addr, bytes, false)))
115                 return 0;
116         else
117                 return _copy_from_iter(addr, bytes, i);
118 }
119 
120 static __always_inline __must_check
121 bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
122 {
123         if (unlikely(!check_copy_size(addr, bytes, false)))
124                 return false;
125         else
126                 return _copy_from_iter_full(addr, bytes, i);
127 }
128 
129 static __always_inline __must_check
130 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
131 {
132         if (unlikely(!check_copy_size(addr, bytes, false)))
133                 return 0;
134         else
135                 return _copy_from_iter_nocache(addr, bytes, i);
136 }
137 
138 static __always_inline __must_check
139 bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
140 {
141         if (unlikely(!check_copy_size(addr, bytes, false)))
142                 return false;
143         else
144                 return _copy_from_iter_full_nocache(addr, bytes, i);
145 }
146 
147 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
148 /*
149  * Note, users like pmem that depend on the stricter semantics of
150  * copy_from_iter_flushcache() than copy_from_iter_nocache() must check for
151  * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
152  * destination is flushed from the cache on return.
153  */
154 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
155 #else
156 #define _copy_from_iter_flushcache _copy_from_iter_nocache
157 #endif
158 
159 static __always_inline __must_check
160 size_t copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
161 {
162         if (unlikely(!check_copy_size(addr, bytes, false)))
163                 return 0;
164         else
165                 return _copy_from_iter_flushcache(addr, bytes, i);
166 }
167 
168 size_t iov_iter_zero(size_t bytes, struct iov_iter *);
169 unsigned long iov_iter_alignment(const struct iov_iter *i);
170 unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
171 void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
172                         unsigned long nr_segs, size_t count);
173 void iov_iter_kvec(struct iov_iter *i, int direction, const struct kvec *kvec,
174                         unsigned long nr_segs, size_t count);
175 void iov_iter_bvec(struct iov_iter *i, int direction, const struct bio_vec *bvec,
176                         unsigned long nr_segs, size_t count);
177 void iov_iter_pipe(struct iov_iter *i, int direction, struct pipe_inode_info *pipe,
178                         size_t count);
179 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
180                         size_t maxsize, unsigned maxpages, size_t *start);
181 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
182                         size_t maxsize, size_t *start);
183 int iov_iter_npages(const struct iov_iter *i, int maxpages);
184 
185 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
186 
187 static inline size_t iov_iter_count(const struct iov_iter *i)
188 {
189         return i->count;
190 }
191 
192 static inline bool iter_is_iovec(const struct iov_iter *i)
193 {
194         return !(i->type & (ITER_BVEC | ITER_KVEC | ITER_PIPE));
195 }
196 
197 /*
198  * Get one of READ or WRITE out of iter->type without any other flags OR'd in
199  * with it.
200  *
201  * The ?: is just for type safety.
202  */
203 #define iov_iter_rw(i) ((0 ? (struct iov_iter *)0 : (i))->type & (READ | WRITE))
204 
205 /*
206  * Cap the iov_iter by given limit; note that the second argument is
207  * *not* the new size - it's upper limit for such.  Passing it a value
208  * greater than the amount of data in iov_iter is fine - it'll just do
209  * nothing in that case.
210  */
211 static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
212 {
213         /*
214          * count doesn't have to fit in size_t - comparison extends both
215          * operands to u64 here and any value that would be truncated by
216          * conversion in assignement is by definition greater than all
217          * values of size_t, including old i->count.
218          */
219         if (i->count > count)
220                 i->count = count;
221 }
222 
223 /*
224  * reexpand a previously truncated iterator; count must be no more than how much
225  * we had shrunk it.
226  */
227 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
228 {
229         i->count = count;
230 }
231 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
232 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
233 bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
234 
235 int import_iovec(int type, const struct iovec __user * uvector,
236                  unsigned nr_segs, unsigned fast_segs,
237                  struct iovec **iov, struct iov_iter *i);
238 
239 #ifdef CONFIG_COMPAT
240 struct compat_iovec;
241 int compat_import_iovec(int type, const struct compat_iovec __user * uvector,
242                  unsigned nr_segs, unsigned fast_segs,
243                  struct iovec **iov, struct iov_iter *i);
244 #endif
245 
246 int import_single_range(int type, void __user *buf, size_t len,
247                  struct iovec *iov, struct iov_iter *i);
248 
249 #endif
250 

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