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 */
31 struct iov_iter_state {
34 unsigned long nr_segs;
44 const struct iovec *iov;
45 const struct kvec *kvec;
46 const struct bio_vec *bvec;
47 struct xarray *xarray;
48 struct pipe_inode_info *pipe;
51 unsigned long nr_segs;
54 unsigned int start_head;
60 static inline enum iter_type iov_iter_type(const struct iov_iter *i)
65 static inline void iov_iter_save_state(struct iov_iter *iter,
66 struct iov_iter_state *state)
68 state->iov_offset = iter->iov_offset;
69 state->count = iter->count;
70 state->nr_segs = iter->nr_segs;
73 static inline bool iter_is_iovec(const struct iov_iter *i)
75 return iov_iter_type(i) == ITER_IOVEC;
78 static inline bool iov_iter_is_kvec(const struct iov_iter *i)
80 return iov_iter_type(i) == ITER_KVEC;
83 static inline bool iov_iter_is_bvec(const struct iov_iter *i)
85 return iov_iter_type(i) == ITER_BVEC;
88 static inline bool iov_iter_is_pipe(const struct iov_iter *i)
90 return iov_iter_type(i) == ITER_PIPE;
93 static inline bool iov_iter_is_discard(const struct iov_iter *i)
95 return iov_iter_type(i) == ITER_DISCARD;
98 static inline bool iov_iter_is_xarray(const struct iov_iter *i)
100 return iov_iter_type(i) == ITER_XARRAY;
103 static inline unsigned char iov_iter_rw(const struct iov_iter *i)
105 return i->data_source ? WRITE : READ;
109 * Total number of bytes covered by an iovec.
111 * NOTE that it is not safe to use this function until all the iovec's
112 * segment lengths have been validated. Because the individual lengths can
113 * overflow a size_t when added together.
115 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
120 for (seg = 0; seg < nr_segs; seg++)
121 ret += iov[seg].iov_len;
125 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
127 return (struct iovec) {
128 .iov_base = iter->iov->iov_base + iter->iov_offset,
129 .iov_len = min(iter->count,
130 iter->iov->iov_len - iter->iov_offset),
134 size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
135 size_t bytes, struct iov_iter *i);
136 void iov_iter_advance(struct iov_iter *i, size_t bytes);
137 void iov_iter_revert(struct iov_iter *i, size_t bytes);
138 size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
139 size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes);
140 size_t iov_iter_single_seg_count(const struct iov_iter *i);
141 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
143 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
146 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
147 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
148 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
150 static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset,
151 size_t bytes, struct iov_iter *i)
153 return copy_page_to_iter(&folio->page, offset, bytes, i);
156 static __always_inline __must_check
157 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
159 if (check_copy_size(addr, bytes, true))
160 return _copy_to_iter(addr, bytes, i);
164 static __always_inline __must_check
165 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
167 if (check_copy_size(addr, bytes, false))
168 return _copy_from_iter(addr, bytes, i);
172 static __always_inline __must_check
173 bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
175 size_t copied = copy_from_iter(addr, bytes, i);
176 if (likely(copied == bytes))
178 iov_iter_revert(i, copied);
182 static __always_inline __must_check
183 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
185 if (check_copy_size(addr, bytes, false))
186 return _copy_from_iter_nocache(addr, bytes, i);
190 static __always_inline __must_check
191 bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
193 size_t copied = copy_from_iter_nocache(addr, bytes, i);
194 if (likely(copied == bytes))
196 iov_iter_revert(i, copied);
200 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
202 * Note, users like pmem that depend on the stricter semantics of
203 * _copy_from_iter_flushcache() than _copy_from_iter_nocache() must check for
204 * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
205 * destination is flushed from the cache on return.
207 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
209 #define _copy_from_iter_flushcache _copy_from_iter_nocache
212 #ifdef CONFIG_ARCH_HAS_COPY_MC
213 size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
215 #define _copy_mc_to_iter _copy_to_iter
218 size_t iov_iter_zero(size_t bytes, struct iov_iter *);
219 bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
221 unsigned long iov_iter_alignment(const struct iov_iter *i);
222 unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
223 void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
224 unsigned long nr_segs, size_t count);
225 void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec,
226 unsigned long nr_segs, size_t count);
227 void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
228 unsigned long nr_segs, size_t count);
229 void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
231 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
232 void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
233 loff_t start, size_t count);
234 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
235 size_t maxsize, unsigned maxpages, size_t *start);
236 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
237 size_t maxsize, size_t *start);
238 int iov_iter_npages(const struct iov_iter *i, int maxpages);
239 void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state);
241 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
243 static inline size_t iov_iter_count(const struct iov_iter *i)
249 * Cap the iov_iter by given limit; note that the second argument is
250 * *not* the new size - it's upper limit for such. Passing it a value
251 * greater than the amount of data in iov_iter is fine - it'll just do
252 * nothing in that case.
254 static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
257 * count doesn't have to fit in size_t - comparison extends both
258 * operands to u64 here and any value that would be truncated by
259 * conversion in assignement is by definition greater than all
260 * values of size_t, including old i->count.
262 if (i->count > count)
267 * reexpand a previously truncated iterator; count must be no more than how much
270 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
276 iov_iter_npages_cap(struct iov_iter *i, int maxpages, size_t max_bytes)
281 if (iov_iter_count(i) > max_bytes) {
282 shorted = iov_iter_count(i) - max_bytes;
283 iov_iter_truncate(i, max_bytes);
285 npages = iov_iter_npages(i, INT_MAX);
287 iov_iter_reexpand(i, iov_iter_count(i) + shorted);
297 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csstate, struct iov_iter *i);
298 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
300 static __always_inline __must_check
301 bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
302 __wsum *csum, struct iov_iter *i)
304 size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
305 if (likely(copied == bytes))
307 iov_iter_revert(i, copied);
310 size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
313 struct iovec *iovec_from_user(const struct iovec __user *uvector,
314 unsigned long nr_segs, unsigned long fast_segs,
315 struct iovec *fast_iov, bool compat);
316 ssize_t import_iovec(int type, const struct iovec __user *uvec,
317 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
319 ssize_t __import_iovec(int type, const struct iovec __user *uvec,
320 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
321 struct iov_iter *i, bool compat);
322 int import_single_range(int type, void __user *buf, size_t len,
323 struct iovec *iov, struct iov_iter *i);