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;
16 typedef unsigned int __bitwise iov_iter_extraction_t;
19 void *iov_base; /* and that should *never* hold a userland pointer */
34 #define ITER_SOURCE 1 // == WRITE
35 #define ITER_DEST 0 // == READ
37 struct iov_iter_state {
40 unsigned long nr_segs;
53 * Hack alert: overlay ubuf_iovec with iovec + count, so
54 * that the members resolve correctly regardless of the type
55 * of iterator used. This means that you can use:
57 * &iter->__ubuf_iovec or iter->__iov
59 * interchangably for the user_backed cases, hence simplifying
60 * some of the cases that need to deal with both.
64 * This really should be a const, but we cannot do that without
65 * also modifying any of the zero-filling iter init functions.
66 * Leave it non-const for now, but it should be treated as such.
68 struct iovec __ubuf_iovec;
71 /* use iter_iov() to get the current vec */
72 const struct iovec *__iov;
73 const struct kvec *kvec;
74 const struct bio_vec *bvec;
75 struct xarray *xarray;
76 struct pipe_inode_info *pipe;
83 unsigned long nr_segs;
86 unsigned int start_head;
92 static inline const struct iovec *iter_iov(const struct iov_iter *iter)
94 if (iter->iter_type == ITER_UBUF)
95 return (const struct iovec *) &iter->__ubuf_iovec;
99 #define iter_iov_addr(iter) (iter_iov(iter)->iov_base + (iter)->iov_offset)
100 #define iter_iov_len(iter) (iter_iov(iter)->iov_len - (iter)->iov_offset)
102 static inline enum iter_type iov_iter_type(const struct iov_iter *i)
107 static inline void iov_iter_save_state(struct iov_iter *iter,
108 struct iov_iter_state *state)
110 state->iov_offset = iter->iov_offset;
111 state->count = iter->count;
112 state->nr_segs = iter->nr_segs;
115 static inline bool iter_is_ubuf(const struct iov_iter *i)
117 return iov_iter_type(i) == ITER_UBUF;
120 static inline bool iter_is_iovec(const struct iov_iter *i)
122 return iov_iter_type(i) == ITER_IOVEC;
125 static inline bool iov_iter_is_kvec(const struct iov_iter *i)
127 return iov_iter_type(i) == ITER_KVEC;
130 static inline bool iov_iter_is_bvec(const struct iov_iter *i)
132 return iov_iter_type(i) == ITER_BVEC;
135 static inline bool iov_iter_is_pipe(const struct iov_iter *i)
137 return iov_iter_type(i) == ITER_PIPE;
140 static inline bool iov_iter_is_discard(const struct iov_iter *i)
142 return iov_iter_type(i) == ITER_DISCARD;
145 static inline bool iov_iter_is_xarray(const struct iov_iter *i)
147 return iov_iter_type(i) == ITER_XARRAY;
150 static inline unsigned char iov_iter_rw(const struct iov_iter *i)
152 return i->data_source ? WRITE : READ;
155 static inline bool user_backed_iter(const struct iov_iter *i)
157 return i->user_backed;
161 * Total number of bytes covered by an iovec.
163 * NOTE that it is not safe to use this function until all the iovec's
164 * segment lengths have been validated. Because the individual lengths can
165 * overflow a size_t when added together.
167 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
172 for (seg = 0; seg < nr_segs; seg++)
173 ret += iov[seg].iov_len;
177 size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
178 size_t bytes, struct iov_iter *i);
179 void iov_iter_advance(struct iov_iter *i, size_t bytes);
180 void iov_iter_revert(struct iov_iter *i, size_t bytes);
181 size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
182 size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes);
183 size_t iov_iter_single_seg_count(const struct iov_iter *i);
184 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
186 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
189 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
190 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
191 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
193 static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset,
194 size_t bytes, struct iov_iter *i)
196 return copy_page_to_iter(&folio->page, offset, bytes, i);
199 static __always_inline __must_check
200 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
202 if (check_copy_size(addr, bytes, true))
203 return _copy_to_iter(addr, bytes, i);
207 static __always_inline __must_check
208 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
210 if (check_copy_size(addr, bytes, false))
211 return _copy_from_iter(addr, bytes, i);
215 static __always_inline __must_check
216 bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
218 size_t copied = copy_from_iter(addr, bytes, i);
219 if (likely(copied == bytes))
221 iov_iter_revert(i, copied);
225 static __always_inline __must_check
226 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
228 if (check_copy_size(addr, bytes, false))
229 return _copy_from_iter_nocache(addr, bytes, i);
233 static __always_inline __must_check
234 bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
236 size_t copied = copy_from_iter_nocache(addr, bytes, i);
237 if (likely(copied == bytes))
239 iov_iter_revert(i, copied);
243 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
245 * Note, users like pmem that depend on the stricter semantics of
246 * _copy_from_iter_flushcache() than _copy_from_iter_nocache() must check for
247 * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
248 * destination is flushed from the cache on return.
250 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
252 #define _copy_from_iter_flushcache _copy_from_iter_nocache
255 #ifdef CONFIG_ARCH_HAS_COPY_MC
256 size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
258 #define _copy_mc_to_iter _copy_to_iter
261 size_t iov_iter_zero(size_t bytes, struct iov_iter *);
262 bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
264 unsigned long iov_iter_alignment(const struct iov_iter *i);
265 unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
266 void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
267 unsigned long nr_segs, size_t count);
268 void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec,
269 unsigned long nr_segs, size_t count);
270 void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
271 unsigned long nr_segs, size_t count);
272 void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
274 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
275 void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
276 loff_t start, size_t count);
277 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
278 size_t maxsize, unsigned maxpages, size_t *start,
279 iov_iter_extraction_t extraction_flags);
280 ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages,
281 size_t maxsize, unsigned maxpages, size_t *start);
282 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
283 struct page ***pages, size_t maxsize, size_t *start,
284 iov_iter_extraction_t extraction_flags);
285 ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, struct page ***pages,
286 size_t maxsize, size_t *start);
287 int iov_iter_npages(const struct iov_iter *i, int maxpages);
288 void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state);
290 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
292 static inline size_t iov_iter_count(const struct iov_iter *i)
298 * Cap the iov_iter by given limit; note that the second argument is
299 * *not* the new size - it's upper limit for such. Passing it a value
300 * greater than the amount of data in iov_iter is fine - it'll just do
301 * nothing in that case.
303 static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
306 * count doesn't have to fit in size_t - comparison extends both
307 * operands to u64 here and any value that would be truncated by
308 * conversion in assignement is by definition greater than all
309 * values of size_t, including old i->count.
311 if (i->count > count)
316 * reexpand a previously truncated iterator; count must be no more than how much
319 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
325 iov_iter_npages_cap(struct iov_iter *i, int maxpages, size_t max_bytes)
330 if (iov_iter_count(i) > max_bytes) {
331 shorted = iov_iter_count(i) - max_bytes;
332 iov_iter_truncate(i, max_bytes);
334 npages = iov_iter_npages(i, maxpages);
336 iov_iter_reexpand(i, iov_iter_count(i) + shorted);
346 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csstate, struct iov_iter *i);
347 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
349 static __always_inline __must_check
350 bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
351 __wsum *csum, struct iov_iter *i)
353 size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
354 if (likely(copied == bytes))
356 iov_iter_revert(i, copied);
359 size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
362 struct iovec *iovec_from_user(const struct iovec __user *uvector,
363 unsigned long nr_segs, unsigned long fast_segs,
364 struct iovec *fast_iov, bool compat);
365 ssize_t import_iovec(int type, const struct iovec __user *uvec,
366 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
368 ssize_t __import_iovec(int type, const struct iovec __user *uvec,
369 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
370 struct iov_iter *i, bool compat);
371 int import_single_range(int type, void __user *buf, size_t len,
372 struct iovec *iov, struct iov_iter *i);
373 int import_ubuf(int type, void __user *buf, size_t len, struct iov_iter *i);
375 static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
376 void __user *buf, size_t count)
378 WARN_ON(direction & ~(READ | WRITE));
379 *i = (struct iov_iter) {
380 .iter_type = ITER_UBUF,
382 .data_source = direction,
388 /* Flags for iov_iter_get/extract_pages*() */
389 /* Allow P2PDMA on the extracted pages */
390 #define ITER_ALLOW_P2PDMA ((__force iov_iter_extraction_t)0x01)
392 ssize_t iov_iter_extract_pages(struct iov_iter *i, struct page ***pages,
393 size_t maxsize, unsigned int maxpages,
394 iov_iter_extraction_t extraction_flags,
398 * iov_iter_extract_will_pin - Indicate how pages from the iterator will be retained
399 * @iter: The iterator
401 * Examine the iterator and indicate by returning true or false as to how, if
402 * at all, pages extracted from the iterator will be retained by the extraction
405 * %true indicates that the pages will have a pin placed in them that the
406 * caller must unpin. This is must be done for DMA/async DIO to force fork()
407 * to forcibly copy a page for the child (the parent must retain the original
410 * %false indicates that no measures are taken and that it's up to the caller
411 * to retain the pages.
413 static inline bool iov_iter_extract_will_pin(const struct iov_iter *iter)
415 return user_backed_iter(iter);