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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 iter_type {
 25         ITER_IOVEC = 0,
 26         ITER_KVEC = 2,
 27         ITER_BVEC = 4,
 28         ITER_PIPE = 8,
 29         ITER_DISCARD = 16,
 30 };
 31 
 32 struct iov_iter {
 33         unsigned int type;
 34         size_t iov_offset;
 35         size_t count;
 36         union {
 37                 const struct iovec *iov;
 38                 const struct kvec *kvec;
 39                 const struct bio_vec *bvec;
 40                 struct pipe_inode_info *pipe;
 41         };
 42         union {
 43                 unsigned long nr_segs;
 44                 struct {
 45                         int idx;
 46                         int start_idx;
 47                 };
 48         };
 49 };
 50 
 51 static inline enum iter_type iov_iter_type(const struct iov_iter *i)
 52 {
 53         return i->type & ~(READ | WRITE);
 54 }
 55 
 56 static inline bool iter_is_iovec(const struct iov_iter *i)
 57 {
 58         return iov_iter_type(i) == ITER_IOVEC;
 59 }
 60 
 61 static inline bool iov_iter_is_kvec(const struct iov_iter *i)
 62 {
 63         return iov_iter_type(i) == ITER_KVEC;
 64 }
 65 
 66 static inline bool iov_iter_is_bvec(const struct iov_iter *i)
 67 {
 68         return iov_iter_type(i) == ITER_BVEC;
 69 }
 70 
 71 static inline bool iov_iter_is_pipe(const struct iov_iter *i)
 72 {
 73         return iov_iter_type(i) == ITER_PIPE;
 74 }
 75 
 76 static inline bool iov_iter_is_discard(const struct iov_iter *i)
 77 {
 78         return iov_iter_type(i) == ITER_DISCARD;
 79 }
 80 
 81 static inline unsigned char iov_iter_rw(const struct iov_iter *i)
 82 {
 83         return i->type & (READ | WRITE);
 84 }
 85 
 86 /*
 87  * Total number of bytes covered by an iovec.
 88  *
 89  * NOTE that it is not safe to use this function until all the iovec's
 90  * segment lengths have been validated.  Because the individual lengths can
 91  * overflow a size_t when added together.
 92  */
 93 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
 94 {
 95         unsigned long seg;
 96         size_t ret = 0;
 97 
 98         for (seg = 0; seg < nr_segs; seg++)
 99                 ret += iov[seg].iov_len;
100         return ret;
101 }
102 
103 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
104 {
105         return (struct iovec) {
106                 .iov_base = iter->iov->iov_base + iter->iov_offset,
107                 .iov_len = min(iter->count,
108                                iter->iov->iov_len - iter->iov_offset),
109         };
110 }
111 
112 #define iov_for_each(iov, iter, start)                          \
113         if (iov_iter_type(start) == ITER_IOVEC ||               \
114             iov_iter_type(start) == ITER_KVEC)                  \
115         for (iter = (start);                                    \
116              (iter).count &&                                    \
117              ((iov = iov_iter_iovec(&(iter))), 1);              \
118              iov_iter_advance(&(iter), (iov).iov_len))
119 
120 size_t iov_iter_copy_from_user_atomic(struct page *page,
121                 struct iov_iter *i, unsigned long offset, size_t bytes);
122 void iov_iter_advance(struct iov_iter *i, size_t bytes);
123 void iov_iter_revert(struct iov_iter *i, size_t bytes);
124 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
125 size_t iov_iter_single_seg_count(const struct iov_iter *i);
126 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
127                          struct iov_iter *i);
128 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
129                          struct iov_iter *i);
130 
131 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
132 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
133 bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i);
134 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
135 bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i);
136 
137 static __always_inline __must_check
138 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
139 {
140         if (unlikely(!check_copy_size(addr, bytes, true)))
141                 return 0;
142         else
143                 return _copy_to_iter(addr, bytes, i);
144 }
145 
146 static __always_inline __must_check
147 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
148 {
149         if (unlikely(!check_copy_size(addr, bytes, false)))
150                 return 0;
151         else
152                 return _copy_from_iter(addr, bytes, i);
153 }
154 
155 static __always_inline __must_check
156 bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
157 {
158         if (unlikely(!check_copy_size(addr, bytes, false)))
159                 return false;
160         else
161                 return _copy_from_iter_full(addr, bytes, i);
162 }
163 
164 static __always_inline __must_check
165 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
166 {
167         if (unlikely(!check_copy_size(addr, bytes, false)))
168                 return 0;
169         else
170                 return _copy_from_iter_nocache(addr, bytes, i);
171 }
172 
173 static __always_inline __must_check
174 bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
175 {
176         if (unlikely(!check_copy_size(addr, bytes, false)))
177                 return false;
178         else
179                 return _copy_from_iter_full_nocache(addr, bytes, i);
180 }
181 
182 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
183 /*
184  * Note, users like pmem that depend on the stricter semantics of
185  * copy_from_iter_flushcache() than copy_from_iter_nocache() must check for
186  * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
187  * destination is flushed from the cache on return.
188  */
189 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
190 #else
191 #define _copy_from_iter_flushcache _copy_from_iter_nocache
192 #endif
193 
194 #ifdef CONFIG_ARCH_HAS_UACCESS_MCSAFE
195 size_t _copy_to_iter_mcsafe(const void *addr, size_t bytes, struct iov_iter *i);
196 #else
197 #define _copy_to_iter_mcsafe _copy_to_iter
198 #endif
199 
200 static __always_inline __must_check
201 size_t copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
202 {
203         if (unlikely(!check_copy_size(addr, bytes, false)))
204                 return 0;
205         else
206                 return _copy_from_iter_flushcache(addr, bytes, i);
207 }
208 
209 static __always_inline __must_check
210 size_t copy_to_iter_mcsafe(void *addr, size_t bytes, struct iov_iter *i)
211 {
212         if (unlikely(!check_copy_size(addr, bytes, true)))
213                 return 0;
214         else
215                 return _copy_to_iter_mcsafe(addr, bytes, i);
216 }
217 
218 size_t iov_iter_zero(size_t bytes, struct iov_iter *);
219 unsigned long iov_iter_alignment(const struct iov_iter *i);
220 unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
221 void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
222                         unsigned long nr_segs, size_t count);
223 void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec,
224                         unsigned long nr_segs, size_t count);
225 void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
226                         unsigned long nr_segs, size_t count);
227 void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
228                         size_t count);
229 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
230 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
231                         size_t maxsize, unsigned maxpages, size_t *start);
232 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
233                         size_t maxsize, size_t *start);
234 int iov_iter_npages(const struct iov_iter *i, int maxpages);
235 
236 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
237 
238 static inline size_t iov_iter_count(const struct iov_iter *i)
239 {
240         return i->count;
241 }
242 
243 /*
244  * Cap the iov_iter by given limit; note that the second argument is
245  * *not* the new size - it's upper limit for such.  Passing it a value
246  * greater than the amount of data in iov_iter is fine - it'll just do
247  * nothing in that case.
248  */
249 static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
250 {
251         /*
252          * count doesn't have to fit in size_t - comparison extends both
253          * operands to u64 here and any value that would be truncated by
254          * conversion in assignement is by definition greater than all
255          * values of size_t, including old i->count.
256          */
257         if (i->count > count)
258                 i->count = count;
259 }
260 
261 /*
262  * reexpand a previously truncated iterator; count must be no more than how much
263  * we had shrunk it.
264  */
265 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
266 {
267         i->count = count;
268 }
269 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
270 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
271 bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
272 
273 int import_iovec(int type, const struct iovec __user * uvector,
274                  unsigned nr_segs, unsigned fast_segs,
275                  struct iovec **iov, struct iov_iter *i);
276 
277 #ifdef CONFIG_COMPAT
278 struct compat_iovec;
279 int compat_import_iovec(int type, const struct compat_iovec __user * uvector,
280                  unsigned nr_segs, unsigned fast_segs,
281                  struct iovec **iov, struct iov_iter *i);
282 #endif
283 
284 int import_single_range(int type, void __user *buf, size_t len,
285                  struct iovec *iov, struct iov_iter *i);
286 
287 int iov_iter_for_each_range(struct iov_iter *i, size_t bytes,
288                             int (*f)(struct kvec *vec, void *context),
289                             void *context);
290 
291 #endif
292 

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