1 /* SPDX-License-Identifier: GPL-2.0-or-later */
3 * Berkeley style UIO structures - Alan Cox 1994.
8 #include <linux/kernel.h>
9 #include <linux/thread_info.h>
10 #include <linux/mm_types.h>
11 #include <uapi/linux/uio.h>
14 struct pipe_inode_info;
17 void *iov_base; /* and that should *never* hold a userland pointer */
32 struct iov_iter_state {
35 unsigned long nr_segs;
49 const struct iovec *iov;
50 const struct kvec *kvec;
51 const struct bio_vec *bvec;
52 struct xarray *xarray;
53 struct pipe_inode_info *pipe;
57 unsigned long nr_segs;
60 unsigned int start_head;
66 static inline enum iter_type iov_iter_type(const struct iov_iter *i)
71 static inline void iov_iter_save_state(struct iov_iter *iter,
72 struct iov_iter_state *state)
74 state->iov_offset = iter->iov_offset;
75 state->count = iter->count;
76 state->nr_segs = iter->nr_segs;
79 static inline bool iter_is_ubuf(const struct iov_iter *i)
81 return iov_iter_type(i) == ITER_UBUF;
84 static inline bool iter_is_iovec(const struct iov_iter *i)
86 return iov_iter_type(i) == ITER_IOVEC;
89 static inline bool iov_iter_is_kvec(const struct iov_iter *i)
91 return iov_iter_type(i) == ITER_KVEC;
94 static inline bool iov_iter_is_bvec(const struct iov_iter *i)
96 return iov_iter_type(i) == ITER_BVEC;
99 static inline bool iov_iter_is_pipe(const struct iov_iter *i)
101 return iov_iter_type(i) == ITER_PIPE;
104 static inline bool iov_iter_is_discard(const struct iov_iter *i)
106 return iov_iter_type(i) == ITER_DISCARD;
109 static inline bool iov_iter_is_xarray(const struct iov_iter *i)
111 return iov_iter_type(i) == ITER_XARRAY;
114 static inline unsigned char iov_iter_rw(const struct iov_iter *i)
116 return i->data_source ? WRITE : READ;
119 static inline bool user_backed_iter(const struct iov_iter *i)
121 return i->user_backed;
125 * Total number of bytes covered by an iovec.
127 * NOTE that it is not safe to use this function until all the iovec's
128 * segment lengths have been validated. Because the individual lengths can
129 * overflow a size_t when added together.
131 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
136 for (seg = 0; seg < nr_segs; seg++)
137 ret += iov[seg].iov_len;
141 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
143 return (struct iovec) {
144 .iov_base = iter->iov->iov_base + iter->iov_offset,
145 .iov_len = min(iter->count,
146 iter->iov->iov_len - iter->iov_offset),
150 size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
151 size_t bytes, struct iov_iter *i);
152 void iov_iter_advance(struct iov_iter *i, size_t bytes);
153 void iov_iter_revert(struct iov_iter *i, size_t bytes);
154 size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
155 size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes);
156 size_t iov_iter_single_seg_count(const struct iov_iter *i);
157 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
159 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
162 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
163 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
164 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
166 static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset,
167 size_t bytes, struct iov_iter *i)
169 return copy_page_to_iter(&folio->page, offset, bytes, i);
172 static __always_inline __must_check
173 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
175 if (check_copy_size(addr, bytes, true))
176 return _copy_to_iter(addr, bytes, i);
180 static __always_inline __must_check
181 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
183 if (check_copy_size(addr, bytes, false))
184 return _copy_from_iter(addr, bytes, i);
188 static __always_inline __must_check
189 bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
191 size_t copied = copy_from_iter(addr, bytes, i);
192 if (likely(copied == bytes))
194 iov_iter_revert(i, copied);
198 static __always_inline __must_check
199 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
201 if (check_copy_size(addr, bytes, false))
202 return _copy_from_iter_nocache(addr, bytes, i);
206 static __always_inline __must_check
207 bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
209 size_t copied = copy_from_iter_nocache(addr, bytes, i);
210 if (likely(copied == bytes))
212 iov_iter_revert(i, copied);
216 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
218 * Note, users like pmem that depend on the stricter semantics of
219 * _copy_from_iter_flushcache() than _copy_from_iter_nocache() must check for
220 * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
221 * destination is flushed from the cache on return.
223 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
225 #define _copy_from_iter_flushcache _copy_from_iter_nocache
228 #ifdef CONFIG_ARCH_HAS_COPY_MC
229 size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
231 #define _copy_mc_to_iter _copy_to_iter
234 size_t iov_iter_zero(size_t bytes, struct iov_iter *);
235 bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
237 unsigned long iov_iter_alignment(const struct iov_iter *i);
238 unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
239 void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
240 unsigned long nr_segs, size_t count);
241 void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec,
242 unsigned long nr_segs, size_t count);
243 void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
244 unsigned long nr_segs, size_t count);
245 void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
247 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
248 void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
249 loff_t start, size_t count);
250 ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages,
251 size_t maxsize, unsigned maxpages, size_t *start);
252 ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, struct page ***pages,
253 size_t maxsize, size_t *start);
254 int iov_iter_npages(const struct iov_iter *i, int maxpages);
255 void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state);
257 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
259 static inline size_t iov_iter_count(const struct iov_iter *i)
265 * Cap the iov_iter by given limit; note that the second argument is
266 * *not* the new size - it's upper limit for such. Passing it a value
267 * greater than the amount of data in iov_iter is fine - it'll just do
268 * nothing in that case.
270 static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
273 * count doesn't have to fit in size_t - comparison extends both
274 * operands to u64 here and any value that would be truncated by
275 * conversion in assignement is by definition greater than all
276 * values of size_t, including old i->count.
278 if (i->count > count)
283 * reexpand a previously truncated iterator; count must be no more than how much
286 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
292 iov_iter_npages_cap(struct iov_iter *i, int maxpages, size_t max_bytes)
297 if (iov_iter_count(i) > max_bytes) {
298 shorted = iov_iter_count(i) - max_bytes;
299 iov_iter_truncate(i, max_bytes);
301 npages = iov_iter_npages(i, maxpages);
303 iov_iter_reexpand(i, iov_iter_count(i) + shorted);
313 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csstate, struct iov_iter *i);
314 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
316 static __always_inline __must_check
317 bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
318 __wsum *csum, struct iov_iter *i)
320 size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
321 if (likely(copied == bytes))
323 iov_iter_revert(i, copied);
326 size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
329 struct iovec *iovec_from_user(const struct iovec __user *uvector,
330 unsigned long nr_segs, unsigned long fast_segs,
331 struct iovec *fast_iov, bool compat);
332 ssize_t import_iovec(int type, const struct iovec __user *uvec,
333 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
335 ssize_t __import_iovec(int type, const struct iovec __user *uvec,
336 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
337 struct iov_iter *i, bool compat);
338 int import_single_range(int type, void __user *buf, size_t len,
339 struct iovec *iov, struct iov_iter *i);
341 static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
342 void __user *buf, size_t count)
344 WARN_ON(direction & ~(READ | WRITE));
345 *i = (struct iov_iter) {
346 .iter_type = ITER_UBUF,
348 .data_source = direction,