Line data Source code
1 : /* SPDX-License-Identifier: GPL-2.0-or-later */
2 : /*
3 : * Berkeley style UIO structures - Alan Cox 1994.
4 : */
5 : #ifndef __LINUX_UIO_H
6 : #define __LINUX_UIO_H
7 :
8 : #include <linux/kernel.h>
9 : #include <linux/thread_info.h>
10 : #include <linux/mm_types.h>
11 : #include <uapi/linux/uio.h>
12 :
13 : struct page;
14 : struct pipe_inode_info;
15 :
16 : typedef unsigned int __bitwise iov_iter_extraction_t;
17 :
18 : struct kvec {
19 : void *iov_base; /* and that should *never* hold a userland pointer */
20 : size_t iov_len;
21 : };
22 :
23 : enum iter_type {
24 : /* iter types */
25 : ITER_IOVEC,
26 : ITER_KVEC,
27 : ITER_BVEC,
28 : ITER_PIPE,
29 : ITER_XARRAY,
30 : ITER_DISCARD,
31 : ITER_UBUF,
32 : };
33 :
34 : #define ITER_SOURCE 1 // == WRITE
35 : #define ITER_DEST 0 // == READ
36 :
37 : struct iov_iter_state {
38 : size_t iov_offset;
39 : size_t count;
40 : unsigned long nr_segs;
41 : };
42 :
43 : struct iov_iter {
44 : u8 iter_type;
45 : bool nofault;
46 : bool data_source;
47 : bool user_backed;
48 : union {
49 : size_t iov_offset;
50 : int last_offset;
51 : };
52 : size_t count;
53 : union {
54 : const struct iovec *iov;
55 : const struct kvec *kvec;
56 : const struct bio_vec *bvec;
57 : struct xarray *xarray;
58 : struct pipe_inode_info *pipe;
59 : void __user *ubuf;
60 : };
61 : union {
62 : unsigned long nr_segs;
63 : struct {
64 : unsigned int head;
65 : unsigned int start_head;
66 : };
67 : loff_t xarray_start;
68 : };
69 : };
70 :
71 : static inline enum iter_type iov_iter_type(const struct iov_iter *i)
72 : {
73 : return i->iter_type;
74 : }
75 :
76 : static inline void iov_iter_save_state(struct iov_iter *iter,
77 : struct iov_iter_state *state)
78 : {
79 0 : state->iov_offset = iter->iov_offset;
80 0 : state->count = iter->count;
81 0 : state->nr_segs = iter->nr_segs;
82 : }
83 :
84 : static inline bool iter_is_ubuf(const struct iov_iter *i)
85 : {
86 0 : return iov_iter_type(i) == ITER_UBUF;
87 : }
88 :
89 : static inline bool iter_is_iovec(const struct iov_iter *i)
90 : {
91 0 : return iov_iter_type(i) == ITER_IOVEC;
92 : }
93 :
94 : static inline bool iov_iter_is_kvec(const struct iov_iter *i)
95 : {
96 0 : return iov_iter_type(i) == ITER_KVEC;
97 : }
98 :
99 : static inline bool iov_iter_is_bvec(const struct iov_iter *i)
100 : {
101 0 : return iov_iter_type(i) == ITER_BVEC;
102 : }
103 :
104 : static inline bool iov_iter_is_pipe(const struct iov_iter *i)
105 : {
106 0 : return iov_iter_type(i) == ITER_PIPE;
107 : }
108 :
109 : static inline bool iov_iter_is_discard(const struct iov_iter *i)
110 : {
111 0 : return iov_iter_type(i) == ITER_DISCARD;
112 : }
113 :
114 : static inline bool iov_iter_is_xarray(const struct iov_iter *i)
115 : {
116 0 : return iov_iter_type(i) == ITER_XARRAY;
117 : }
118 :
119 : static inline unsigned char iov_iter_rw(const struct iov_iter *i)
120 : {
121 : return i->data_source ? WRITE : READ;
122 : }
123 :
124 : static inline bool user_backed_iter(const struct iov_iter *i)
125 : {
126 : return i->user_backed;
127 : }
128 :
129 : /*
130 : * Total number of bytes covered by an iovec.
131 : *
132 : * NOTE that it is not safe to use this function until all the iovec's
133 : * segment lengths have been validated. Because the individual lengths can
134 : * overflow a size_t when added together.
135 : */
136 : static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
137 : {
138 : unsigned long seg;
139 : size_t ret = 0;
140 :
141 : for (seg = 0; seg < nr_segs; seg++)
142 : ret += iov[seg].iov_len;
143 : return ret;
144 : }
145 :
146 : static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
147 : {
148 : return (struct iovec) {
149 0 : .iov_base = iter->iov->iov_base + iter->iov_offset,
150 0 : .iov_len = min(iter->count,
151 : iter->iov->iov_len - iter->iov_offset),
152 : };
153 : }
154 :
155 : size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
156 : size_t bytes, struct iov_iter *i);
157 : void iov_iter_advance(struct iov_iter *i, size_t bytes);
158 : void iov_iter_revert(struct iov_iter *i, size_t bytes);
159 : size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
160 : size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes);
161 : size_t iov_iter_single_seg_count(const struct iov_iter *i);
162 : size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
163 : struct iov_iter *i);
164 : size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
165 : struct iov_iter *i);
166 :
167 : size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
168 : size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
169 : size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
170 :
171 : static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset,
172 : size_t bytes, struct iov_iter *i)
173 : {
174 0 : return copy_page_to_iter(&folio->page, offset, bytes, i);
175 : }
176 :
177 : static __always_inline __must_check
178 : size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
179 : {
180 0 : if (check_copy_size(addr, bytes, true))
181 0 : return _copy_to_iter(addr, bytes, i);
182 : return 0;
183 : }
184 :
185 : static __always_inline __must_check
186 : size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
187 : {
188 0 : if (check_copy_size(addr, bytes, false))
189 0 : return _copy_from_iter(addr, bytes, i);
190 : return 0;
191 : }
192 :
193 : static __always_inline __must_check
194 : bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
195 : {
196 0 : size_t copied = copy_from_iter(addr, bytes, i);
197 0 : if (likely(copied == bytes))
198 : return true;
199 0 : iov_iter_revert(i, copied);
200 : return false;
201 : }
202 :
203 : static __always_inline __must_check
204 : size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
205 : {
206 : if (check_copy_size(addr, bytes, false))
207 : return _copy_from_iter_nocache(addr, bytes, i);
208 : return 0;
209 : }
210 :
211 : static __always_inline __must_check
212 : bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
213 : {
214 : size_t copied = copy_from_iter_nocache(addr, bytes, i);
215 : if (likely(copied == bytes))
216 : return true;
217 : iov_iter_revert(i, copied);
218 : return false;
219 : }
220 :
221 : #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
222 : /*
223 : * Note, users like pmem that depend on the stricter semantics of
224 : * _copy_from_iter_flushcache() than _copy_from_iter_nocache() must check for
225 : * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
226 : * destination is flushed from the cache on return.
227 : */
228 : size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
229 : #else
230 : #define _copy_from_iter_flushcache _copy_from_iter_nocache
231 : #endif
232 :
233 : #ifdef CONFIG_ARCH_HAS_COPY_MC
234 : size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
235 : #else
236 : #define _copy_mc_to_iter _copy_to_iter
237 : #endif
238 :
239 : size_t iov_iter_zero(size_t bytes, struct iov_iter *);
240 : bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
241 : unsigned len_mask);
242 : unsigned long iov_iter_alignment(const struct iov_iter *i);
243 : unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
244 : void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
245 : unsigned long nr_segs, size_t count);
246 : void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec,
247 : unsigned long nr_segs, size_t count);
248 : void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
249 : unsigned long nr_segs, size_t count);
250 : void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
251 : size_t count);
252 : void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
253 : void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
254 : loff_t start, size_t count);
255 : ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
256 : size_t maxsize, unsigned maxpages, size_t *start,
257 : iov_iter_extraction_t extraction_flags);
258 : ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages,
259 : size_t maxsize, unsigned maxpages, size_t *start);
260 : ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
261 : struct page ***pages, size_t maxsize, size_t *start,
262 : iov_iter_extraction_t extraction_flags);
263 : ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, struct page ***pages,
264 : size_t maxsize, size_t *start);
265 : int iov_iter_npages(const struct iov_iter *i, int maxpages);
266 : void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state);
267 :
268 : const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
269 :
270 : static inline size_t iov_iter_count(const struct iov_iter *i)
271 : {
272 : return i->count;
273 : }
274 :
275 : /*
276 : * Cap the iov_iter by given limit; note that the second argument is
277 : * *not* the new size - it's upper limit for such. Passing it a value
278 : * greater than the amount of data in iov_iter is fine - it'll just do
279 : * nothing in that case.
280 : */
281 : static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
282 : {
283 : /*
284 : * count doesn't have to fit in size_t - comparison extends both
285 : * operands to u64 here and any value that would be truncated by
286 : * conversion in assignement is by definition greater than all
287 : * values of size_t, including old i->count.
288 : */
289 0 : if (i->count > count)
290 0 : i->count = count;
291 : }
292 :
293 : /*
294 : * reexpand a previously truncated iterator; count must be no more than how much
295 : * we had shrunk it.
296 : */
297 : static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
298 : {
299 0 : i->count = count;
300 : }
301 :
302 : static inline int
303 : iov_iter_npages_cap(struct iov_iter *i, int maxpages, size_t max_bytes)
304 : {
305 : size_t shorted = 0;
306 : int npages;
307 :
308 : if (iov_iter_count(i) > max_bytes) {
309 : shorted = iov_iter_count(i) - max_bytes;
310 : iov_iter_truncate(i, max_bytes);
311 : }
312 : npages = iov_iter_npages(i, maxpages);
313 : if (shorted)
314 : iov_iter_reexpand(i, iov_iter_count(i) + shorted);
315 :
316 : return npages;
317 : }
318 :
319 : struct csum_state {
320 : __wsum csum;
321 : size_t off;
322 : };
323 :
324 : size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csstate, struct iov_iter *i);
325 : size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
326 :
327 : static __always_inline __must_check
328 : bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
329 : __wsum *csum, struct iov_iter *i)
330 : {
331 : size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
332 : if (likely(copied == bytes))
333 : return true;
334 : iov_iter_revert(i, copied);
335 : return false;
336 : }
337 : size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
338 : struct iov_iter *i);
339 :
340 : struct iovec *iovec_from_user(const struct iovec __user *uvector,
341 : unsigned long nr_segs, unsigned long fast_segs,
342 : struct iovec *fast_iov, bool compat);
343 : ssize_t import_iovec(int type, const struct iovec __user *uvec,
344 : unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
345 : struct iov_iter *i);
346 : ssize_t __import_iovec(int type, const struct iovec __user *uvec,
347 : unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
348 : struct iov_iter *i, bool compat);
349 : int import_single_range(int type, void __user *buf, size_t len,
350 : struct iovec *iov, struct iov_iter *i);
351 : int import_ubuf(int type, void __user *buf, size_t len, struct iov_iter *i);
352 :
353 0 : static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
354 : void __user *buf, size_t count)
355 : {
356 0 : WARN_ON(direction & ~(READ | WRITE));
357 0 : *i = (struct iov_iter) {
358 : .iter_type = ITER_UBUF,
359 : .user_backed = true,
360 : .data_source = direction,
361 : .ubuf = buf,
362 : .count = count
363 : };
364 0 : }
365 : /* Flags for iov_iter_get/extract_pages*() */
366 : /* Allow P2PDMA on the extracted pages */
367 : #define ITER_ALLOW_P2PDMA ((__force iov_iter_extraction_t)0x01)
368 :
369 : ssize_t iov_iter_extract_pages(struct iov_iter *i, struct page ***pages,
370 : size_t maxsize, unsigned int maxpages,
371 : iov_iter_extraction_t extraction_flags,
372 : size_t *offset0);
373 :
374 : /**
375 : * iov_iter_extract_will_pin - Indicate how pages from the iterator will be retained
376 : * @iter: The iterator
377 : *
378 : * Examine the iterator and indicate by returning true or false as to how, if
379 : * at all, pages extracted from the iterator will be retained by the extraction
380 : * function.
381 : *
382 : * %true indicates that the pages will have a pin placed in them that the
383 : * caller must unpin. This is must be done for DMA/async DIO to force fork()
384 : * to forcibly copy a page for the child (the parent must retain the original
385 : * page).
386 : *
387 : * %false indicates that no measures are taken and that it's up to the caller
388 : * to retain the pages.
389 : */
390 : static inline bool iov_iter_extract_will_pin(const struct iov_iter *iter)
391 : {
392 : return user_backed_iter(iter);
393 : }
394 :
395 : #endif
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