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 #define ITER_SOURCE 1 // == WRITE
33 #define ITER_DEST 0 // == READ
35 struct iov_iter_state {
38 unsigned long nr_segs;
52 const struct iovec *iov;
53 const struct kvec *kvec;
54 const struct bio_vec *bvec;
55 struct xarray *xarray;
56 struct pipe_inode_info *pipe;
60 unsigned long nr_segs;
63 unsigned int start_head;
69 static inline enum iter_type iov_iter_type(const struct iov_iter *i)
74 static inline void iov_iter_save_state(struct iov_iter *iter,
75 struct iov_iter_state *state)
77 state->iov_offset = iter->iov_offset;
78 state->count = iter->count;
79 state->nr_segs = iter->nr_segs;
82 static inline bool iter_is_ubuf(const struct iov_iter *i)
84 return iov_iter_type(i) == ITER_UBUF;
87 static inline bool iter_is_iovec(const struct iov_iter *i)
89 return iov_iter_type(i) == ITER_IOVEC;
92 static inline bool iov_iter_is_kvec(const struct iov_iter *i)
94 return iov_iter_type(i) == ITER_KVEC;
97 static inline bool iov_iter_is_bvec(const struct iov_iter *i)
99 return iov_iter_type(i) == ITER_BVEC;
102 static inline bool iov_iter_is_pipe(const struct iov_iter *i)
104 return iov_iter_type(i) == ITER_PIPE;
107 static inline bool iov_iter_is_discard(const struct iov_iter *i)
109 return iov_iter_type(i) == ITER_DISCARD;
112 static inline bool iov_iter_is_xarray(const struct iov_iter *i)
114 return iov_iter_type(i) == ITER_XARRAY;
117 static inline unsigned char iov_iter_rw(const struct iov_iter *i)
119 return i->data_source ? WRITE : READ;
122 static inline bool user_backed_iter(const struct iov_iter *i)
124 return i->user_backed;
128 * Total number of bytes covered by an iovec.
130 * NOTE that it is not safe to use this function until all the iovec's
131 * segment lengths have been validated. Because the individual lengths can
132 * overflow a size_t when added together.
134 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
139 for (seg = 0; seg < nr_segs; seg++)
140 ret += iov[seg].iov_len;
144 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
146 return (struct iovec) {
147 .iov_base = iter->iov->iov_base + iter->iov_offset,
148 .iov_len = min(iter->count,
149 iter->iov->iov_len - iter->iov_offset),
153 size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
154 size_t bytes, struct iov_iter *i);
155 void iov_iter_advance(struct iov_iter *i, size_t bytes);
156 void iov_iter_revert(struct iov_iter *i, size_t bytes);
157 size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
158 size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes);
159 size_t iov_iter_single_seg_count(const struct iov_iter *i);
160 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
162 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
165 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
166 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
167 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
169 static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset,
170 size_t bytes, struct iov_iter *i)
172 return copy_page_to_iter(&folio->page, offset, bytes, i);
175 static __always_inline __must_check
176 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
178 if (check_copy_size(addr, bytes, true))
179 return _copy_to_iter(addr, bytes, i);
183 static __always_inline __must_check
184 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
186 if (check_copy_size(addr, bytes, false))
187 return _copy_from_iter(addr, bytes, i);
191 static __always_inline __must_check
192 bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
194 size_t copied = copy_from_iter(addr, bytes, i);
195 if (likely(copied == bytes))
197 iov_iter_revert(i, copied);
201 static __always_inline __must_check
202 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
204 if (check_copy_size(addr, bytes, false))
205 return _copy_from_iter_nocache(addr, bytes, i);
209 static __always_inline __must_check
210 bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
212 size_t copied = copy_from_iter_nocache(addr, bytes, i);
213 if (likely(copied == bytes))
215 iov_iter_revert(i, copied);
219 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
221 * Note, users like pmem that depend on the stricter semantics of
222 * _copy_from_iter_flushcache() than _copy_from_iter_nocache() must check for
223 * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
224 * destination is flushed from the cache on return.
226 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
228 #define _copy_from_iter_flushcache _copy_from_iter_nocache
231 #ifdef CONFIG_ARCH_HAS_COPY_MC
232 size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
234 #define _copy_mc_to_iter _copy_to_iter
237 size_t iov_iter_zero(size_t bytes, struct iov_iter *);
238 bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
240 unsigned long iov_iter_alignment(const struct iov_iter *i);
241 unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
242 void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
243 unsigned long nr_segs, size_t count);
244 void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec,
245 unsigned long nr_segs, size_t count);
246 void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
247 unsigned long nr_segs, size_t count);
248 void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
250 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
251 void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
252 loff_t start, size_t count);
253 ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages,
254 size_t maxsize, unsigned maxpages, size_t *start);
255 ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, struct page ***pages,
256 size_t maxsize, size_t *start);
257 int iov_iter_npages(const struct iov_iter *i, int maxpages);
258 void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state);
260 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
262 static inline size_t iov_iter_count(const struct iov_iter *i)
268 * Cap the iov_iter by given limit; note that the second argument is
269 * *not* the new size - it's upper limit for such. Passing it a value
270 * greater than the amount of data in iov_iter is fine - it'll just do
271 * nothing in that case.
273 static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
276 * count doesn't have to fit in size_t - comparison extends both
277 * operands to u64 here and any value that would be truncated by
278 * conversion in assignement is by definition greater than all
279 * values of size_t, including old i->count.
281 if (i->count > count)
286 * reexpand a previously truncated iterator; count must be no more than how much
289 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
295 iov_iter_npages_cap(struct iov_iter *i, int maxpages, size_t max_bytes)
300 if (iov_iter_count(i) > max_bytes) {
301 shorted = iov_iter_count(i) - max_bytes;
302 iov_iter_truncate(i, max_bytes);
304 npages = iov_iter_npages(i, maxpages);
306 iov_iter_reexpand(i, iov_iter_count(i) + shorted);
316 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csstate, struct iov_iter *i);
317 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
319 static __always_inline __must_check
320 bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
321 __wsum *csum, struct iov_iter *i)
323 size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
324 if (likely(copied == bytes))
326 iov_iter_revert(i, copied);
329 size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
332 struct iovec *iovec_from_user(const struct iovec __user *uvector,
333 unsigned long nr_segs, unsigned long fast_segs,
334 struct iovec *fast_iov, bool compat);
335 ssize_t import_iovec(int type, const struct iovec __user *uvec,
336 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
338 ssize_t __import_iovec(int type, const struct iovec __user *uvec,
339 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
340 struct iov_iter *i, bool compat);
341 int import_single_range(int type, void __user *buf, size_t len,
342 struct iovec *iov, struct iov_iter *i);
344 static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
345 void __user *buf, size_t count)
347 WARN_ON(direction & ~(READ | WRITE));
348 *i = (struct iov_iter) {
349 .iter_type = ITER_UBUF,
351 .data_source = direction,