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 copy_mc;
46 : bool nofault;
47 : bool data_source;
48 : bool user_backed;
49 : union {
50 : size_t iov_offset;
51 : int last_offset;
52 : };
53 : /*
54 : * Hack alert: overlay ubuf_iovec with iovec + count, so
55 : * that the members resolve correctly regardless of the type
56 : * of iterator used. This means that you can use:
57 : *
58 : * &iter->__ubuf_iovec or iter->__iov
59 : *
60 : * interchangably for the user_backed cases, hence simplifying
61 : * some of the cases that need to deal with both.
62 : */
63 : union {
64 : /*
65 : * This really should be a const, but we cannot do that without
66 : * also modifying any of the zero-filling iter init functions.
67 : * Leave it non-const for now, but it should be treated as such.
68 : */
69 : struct iovec __ubuf_iovec;
70 : struct {
71 : union {
72 : /* use iter_iov() to get the current vec */
73 : const struct iovec *__iov;
74 : const struct kvec *kvec;
75 : const struct bio_vec *bvec;
76 : struct xarray *xarray;
77 : struct pipe_inode_info *pipe;
78 : void __user *ubuf;
79 : };
80 : size_t count;
81 : };
82 : };
83 : union {
84 : unsigned long nr_segs;
85 : struct {
86 : unsigned int head;
87 : unsigned int start_head;
88 : };
89 : loff_t xarray_start;
90 : };
91 : };
92 :
93 : static inline const struct iovec *iter_iov(const struct iov_iter *iter)
94 : {
95 0 : if (iter->iter_type == ITER_UBUF)
96 0 : return (const struct iovec *) &iter->__ubuf_iovec;
97 0 : return iter->__iov;
98 : }
99 :
100 : #define iter_iov_addr(iter) (iter_iov(iter)->iov_base + (iter)->iov_offset)
101 : #define iter_iov_len(iter) (iter_iov(iter)->iov_len - (iter)->iov_offset)
102 :
103 : static inline enum iter_type iov_iter_type(const struct iov_iter *i)
104 : {
105 : return i->iter_type;
106 : }
107 :
108 : static inline void iov_iter_save_state(struct iov_iter *iter,
109 : struct iov_iter_state *state)
110 : {
111 0 : state->iov_offset = iter->iov_offset;
112 0 : state->count = iter->count;
113 0 : state->nr_segs = iter->nr_segs;
114 : }
115 :
116 : static inline bool iter_is_ubuf(const struct iov_iter *i)
117 : {
118 0 : return iov_iter_type(i) == ITER_UBUF;
119 : }
120 :
121 : static inline bool iter_is_iovec(const struct iov_iter *i)
122 : {
123 0 : return iov_iter_type(i) == ITER_IOVEC;
124 : }
125 :
126 : static inline bool iov_iter_is_kvec(const struct iov_iter *i)
127 : {
128 0 : return iov_iter_type(i) == ITER_KVEC;
129 : }
130 :
131 : static inline bool iov_iter_is_bvec(const struct iov_iter *i)
132 : {
133 0 : return iov_iter_type(i) == ITER_BVEC;
134 : }
135 :
136 : static inline bool iov_iter_is_pipe(const struct iov_iter *i)
137 : {
138 0 : return iov_iter_type(i) == ITER_PIPE;
139 : }
140 :
141 : static inline bool iov_iter_is_discard(const struct iov_iter *i)
142 : {
143 0 : return iov_iter_type(i) == ITER_DISCARD;
144 : }
145 :
146 : static inline bool iov_iter_is_xarray(const struct iov_iter *i)
147 : {
148 0 : return iov_iter_type(i) == ITER_XARRAY;
149 : }
150 :
151 : static inline unsigned char iov_iter_rw(const struct iov_iter *i)
152 : {
153 : return i->data_source ? WRITE : READ;
154 : }
155 :
156 : static inline bool user_backed_iter(const struct iov_iter *i)
157 : {
158 : return i->user_backed;
159 : }
160 :
161 : /*
162 : * Total number of bytes covered by an iovec.
163 : *
164 : * NOTE that it is not safe to use this function until all the iovec's
165 : * segment lengths have been validated. Because the individual lengths can
166 : * overflow a size_t when added together.
167 : */
168 : static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
169 : {
170 : unsigned long seg;
171 : size_t ret = 0;
172 :
173 : for (seg = 0; seg < nr_segs; seg++)
174 : ret += iov[seg].iov_len;
175 : return ret;
176 : }
177 :
178 : size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
179 : size_t bytes, struct iov_iter *i);
180 : void iov_iter_advance(struct iov_iter *i, size_t bytes);
181 : void iov_iter_revert(struct iov_iter *i, size_t bytes);
182 : size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
183 : size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes);
184 : size_t iov_iter_single_seg_count(const struct iov_iter *i);
185 : size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
186 : struct iov_iter *i);
187 : size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
188 : struct iov_iter *i);
189 :
190 : size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
191 : size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
192 : size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
193 :
194 : static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset,
195 : size_t bytes, struct iov_iter *i)
196 : {
197 0 : return copy_page_to_iter(&folio->page, offset, bytes, i);
198 : }
199 : size_t copy_page_to_iter_nofault(struct page *page, unsigned offset,
200 : size_t bytes, struct iov_iter *i);
201 :
202 : static __always_inline __must_check
203 : size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
204 : {
205 0 : if (check_copy_size(addr, bytes, true))
206 0 : return _copy_to_iter(addr, bytes, i);
207 : return 0;
208 : }
209 :
210 : static __always_inline __must_check
211 : size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
212 : {
213 0 : if (check_copy_size(addr, bytes, false))
214 0 : return _copy_from_iter(addr, bytes, i);
215 : return 0;
216 : }
217 :
218 : static __always_inline __must_check
219 : bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
220 : {
221 0 : size_t copied = copy_from_iter(addr, bytes, i);
222 0 : if (likely(copied == bytes))
223 : return true;
224 0 : iov_iter_revert(i, copied);
225 : return false;
226 : }
227 :
228 : static __always_inline __must_check
229 : size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
230 : {
231 : if (check_copy_size(addr, bytes, false))
232 : return _copy_from_iter_nocache(addr, bytes, i);
233 : return 0;
234 : }
235 :
236 : static __always_inline __must_check
237 : bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
238 : {
239 : size_t copied = copy_from_iter_nocache(addr, bytes, i);
240 : if (likely(copied == bytes))
241 : return true;
242 : iov_iter_revert(i, copied);
243 : return false;
244 : }
245 :
246 : #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
247 : /*
248 : * Note, users like pmem that depend on the stricter semantics of
249 : * _copy_from_iter_flushcache() than _copy_from_iter_nocache() must check for
250 : * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
251 : * destination is flushed from the cache on return.
252 : */
253 : size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
254 : #else
255 : #define _copy_from_iter_flushcache _copy_from_iter_nocache
256 : #endif
257 :
258 : #ifdef CONFIG_ARCH_HAS_COPY_MC
259 : size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
260 : static inline void iov_iter_set_copy_mc(struct iov_iter *i)
261 : {
262 : i->copy_mc = true;
263 : }
264 :
265 : static inline bool iov_iter_is_copy_mc(const struct iov_iter *i)
266 : {
267 : return i->copy_mc;
268 : }
269 : #else
270 : #define _copy_mc_to_iter _copy_to_iter
271 : static inline void iov_iter_set_copy_mc(struct iov_iter *i) { }
272 : static inline bool iov_iter_is_copy_mc(const struct iov_iter *i)
273 : {
274 : return false;
275 : }
276 : #endif
277 :
278 : size_t iov_iter_zero(size_t bytes, struct iov_iter *);
279 : bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
280 : unsigned len_mask);
281 : unsigned long iov_iter_alignment(const struct iov_iter *i);
282 : unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
283 : void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
284 : unsigned long nr_segs, size_t count);
285 : void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec,
286 : unsigned long nr_segs, size_t count);
287 : void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
288 : unsigned long nr_segs, size_t count);
289 : void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
290 : size_t count);
291 : void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
292 : void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
293 : loff_t start, size_t count);
294 : ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
295 : size_t maxsize, unsigned maxpages, size_t *start,
296 : iov_iter_extraction_t extraction_flags);
297 : ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages,
298 : size_t maxsize, unsigned maxpages, size_t *start);
299 : ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
300 : struct page ***pages, size_t maxsize, size_t *start,
301 : iov_iter_extraction_t extraction_flags);
302 : ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, struct page ***pages,
303 : size_t maxsize, size_t *start);
304 : int iov_iter_npages(const struct iov_iter *i, int maxpages);
305 : void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state);
306 :
307 : const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
308 :
309 : static inline size_t iov_iter_count(const struct iov_iter *i)
310 : {
311 : return i->count;
312 : }
313 :
314 : /*
315 : * Cap the iov_iter by given limit; note that the second argument is
316 : * *not* the new size - it's upper limit for such. Passing it a value
317 : * greater than the amount of data in iov_iter is fine - it'll just do
318 : * nothing in that case.
319 : */
320 : static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
321 : {
322 : /*
323 : * count doesn't have to fit in size_t - comparison extends both
324 : * operands to u64 here and any value that would be truncated by
325 : * conversion in assignement is by definition greater than all
326 : * values of size_t, including old i->count.
327 : */
328 0 : if (i->count > count)
329 0 : i->count = count;
330 : }
331 :
332 : /*
333 : * reexpand a previously truncated iterator; count must be no more than how much
334 : * we had shrunk it.
335 : */
336 : static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
337 : {
338 0 : i->count = count;
339 : }
340 :
341 : static inline int
342 : iov_iter_npages_cap(struct iov_iter *i, int maxpages, size_t max_bytes)
343 : {
344 : size_t shorted = 0;
345 : int npages;
346 :
347 : if (iov_iter_count(i) > max_bytes) {
348 : shorted = iov_iter_count(i) - max_bytes;
349 : iov_iter_truncate(i, max_bytes);
350 : }
351 : npages = iov_iter_npages(i, maxpages);
352 : if (shorted)
353 : iov_iter_reexpand(i, iov_iter_count(i) + shorted);
354 :
355 : return npages;
356 : }
357 :
358 : struct csum_state {
359 : __wsum csum;
360 : size_t off;
361 : };
362 :
363 : size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csstate, struct iov_iter *i);
364 : size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
365 :
366 : static __always_inline __must_check
367 : bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
368 : __wsum *csum, struct iov_iter *i)
369 : {
370 : size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
371 : if (likely(copied == bytes))
372 : return true;
373 : iov_iter_revert(i, copied);
374 : return false;
375 : }
376 : size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
377 : struct iov_iter *i);
378 :
379 : struct iovec *iovec_from_user(const struct iovec __user *uvector,
380 : unsigned long nr_segs, unsigned long fast_segs,
381 : struct iovec *fast_iov, bool compat);
382 : ssize_t import_iovec(int type, const struct iovec __user *uvec,
383 : unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
384 : struct iov_iter *i);
385 : ssize_t __import_iovec(int type, const struct iovec __user *uvec,
386 : unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
387 : struct iov_iter *i, bool compat);
388 : int import_single_range(int type, void __user *buf, size_t len,
389 : struct iovec *iov, struct iov_iter *i);
390 : int import_ubuf(int type, void __user *buf, size_t len, struct iov_iter *i);
391 :
392 0 : static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
393 : void __user *buf, size_t count)
394 : {
395 0 : WARN_ON(direction & ~(READ | WRITE));
396 0 : *i = (struct iov_iter) {
397 : .iter_type = ITER_UBUF,
398 : .copy_mc = false,
399 : .user_backed = true,
400 : .data_source = direction,
401 : .ubuf = buf,
402 : .count = count,
403 : .nr_segs = 1
404 : };
405 0 : }
406 : /* Flags for iov_iter_get/extract_pages*() */
407 : /* Allow P2PDMA on the extracted pages */
408 : #define ITER_ALLOW_P2PDMA ((__force iov_iter_extraction_t)0x01)
409 :
410 : ssize_t iov_iter_extract_pages(struct iov_iter *i, struct page ***pages,
411 : size_t maxsize, unsigned int maxpages,
412 : iov_iter_extraction_t extraction_flags,
413 : size_t *offset0);
414 :
415 : /**
416 : * iov_iter_extract_will_pin - Indicate how pages from the iterator will be retained
417 : * @iter: The iterator
418 : *
419 : * Examine the iterator and indicate by returning true or false as to how, if
420 : * at all, pages extracted from the iterator will be retained by the extraction
421 : * function.
422 : *
423 : * %true indicates that the pages will have a pin placed in them that the
424 : * caller must unpin. This is must be done for DMA/async DIO to force fork()
425 : * to forcibly copy a page for the child (the parent must retain the original
426 : * page).
427 : *
428 : * %false indicates that no measures are taken and that it's up to the caller
429 : * to retain the pages.
430 : */
431 : static inline bool iov_iter_extract_will_pin(const struct iov_iter *iter)
432 : {
433 : return user_backed_iter(iter);
434 : }
435 :
436 : #endif
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