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 :
15 : typedef unsigned int __bitwise iov_iter_extraction_t;
16 :
17 : struct kvec {
18 : void *iov_base; /* and that should *never* hold a userland pointer */
19 : size_t iov_len;
20 : };
21 :
22 : enum iter_type {
23 : /* iter types */
24 : ITER_IOVEC,
25 : ITER_KVEC,
26 : ITER_BVEC,
27 : ITER_XARRAY,
28 : ITER_DISCARD,
29 : ITER_UBUF,
30 : };
31 :
32 : #define ITER_SOURCE 1 // == WRITE
33 : #define ITER_DEST 0 // == READ
34 :
35 : struct iov_iter_state {
36 : size_t iov_offset;
37 : size_t count;
38 : unsigned long nr_segs;
39 : };
40 :
41 : struct iov_iter {
42 : u8 iter_type;
43 : bool copy_mc;
44 : bool nofault;
45 : bool data_source;
46 : bool user_backed;
47 : union {
48 : size_t iov_offset;
49 : int last_offset;
50 : };
51 : /*
52 : * Hack alert: overlay ubuf_iovec with iovec + count, so
53 : * that the members resolve correctly regardless of the type
54 : * of iterator used. This means that you can use:
55 : *
56 : * &iter->__ubuf_iovec or iter->__iov
57 : *
58 : * interchangably for the user_backed cases, hence simplifying
59 : * some of the cases that need to deal with both.
60 : */
61 : union {
62 : /*
63 : * This really should be a const, but we cannot do that without
64 : * also modifying any of the zero-filling iter init functions.
65 : * Leave it non-const for now, but it should be treated as such.
66 : */
67 : struct iovec __ubuf_iovec;
68 : struct {
69 : union {
70 : /* use iter_iov() to get the current vec */
71 : const struct iovec *__iov;
72 : const struct kvec *kvec;
73 : const struct bio_vec *bvec;
74 : struct xarray *xarray;
75 : void __user *ubuf;
76 : };
77 : size_t count;
78 : };
79 : };
80 : union {
81 : unsigned long nr_segs;
82 : loff_t xarray_start;
83 : };
84 : };
85 :
86 : static inline const struct iovec *iter_iov(const struct iov_iter *iter)
87 : {
88 0 : if (iter->iter_type == ITER_UBUF)
89 0 : return (const struct iovec *) &iter->__ubuf_iovec;
90 0 : return iter->__iov;
91 : }
92 :
93 : #define iter_iov_addr(iter) (iter_iov(iter)->iov_base + (iter)->iov_offset)
94 : #define iter_iov_len(iter) (iter_iov(iter)->iov_len - (iter)->iov_offset)
95 :
96 : static inline enum iter_type iov_iter_type(const struct iov_iter *i)
97 : {
98 0 : return i->iter_type;
99 : }
100 :
101 : static inline void iov_iter_save_state(struct iov_iter *iter,
102 : struct iov_iter_state *state)
103 : {
104 0 : state->iov_offset = iter->iov_offset;
105 0 : state->count = iter->count;
106 0 : state->nr_segs = iter->nr_segs;
107 : }
108 :
109 : static inline bool iter_is_ubuf(const struct iov_iter *i)
110 : {
111 0 : return iov_iter_type(i) == ITER_UBUF;
112 : }
113 :
114 : static inline bool iter_is_iovec(const struct iov_iter *i)
115 : {
116 0 : return iov_iter_type(i) == ITER_IOVEC;
117 : }
118 :
119 : static inline bool iov_iter_is_kvec(const struct iov_iter *i)
120 : {
121 0 : return iov_iter_type(i) == ITER_KVEC;
122 : }
123 :
124 : static inline bool iov_iter_is_bvec(const struct iov_iter *i)
125 : {
126 0 : return iov_iter_type(i) == ITER_BVEC;
127 : }
128 :
129 : static inline bool iov_iter_is_discard(const struct iov_iter *i)
130 : {
131 0 : return iov_iter_type(i) == ITER_DISCARD;
132 : }
133 :
134 : static inline bool iov_iter_is_xarray(const struct iov_iter *i)
135 : {
136 0 : return iov_iter_type(i) == ITER_XARRAY;
137 : }
138 :
139 : static inline unsigned char iov_iter_rw(const struct iov_iter *i)
140 : {
141 : return i->data_source ? WRITE : READ;
142 : }
143 :
144 : static inline bool user_backed_iter(const struct iov_iter *i)
145 : {
146 : return i->user_backed;
147 : }
148 :
149 : /*
150 : * Total number of bytes covered by an iovec.
151 : *
152 : * NOTE that it is not safe to use this function until all the iovec's
153 : * segment lengths have been validated. Because the individual lengths can
154 : * overflow a size_t when added together.
155 : */
156 : static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
157 : {
158 : unsigned long seg;
159 : size_t ret = 0;
160 :
161 : for (seg = 0; seg < nr_segs; seg++)
162 : ret += iov[seg].iov_len;
163 : return ret;
164 : }
165 :
166 : size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
167 : size_t bytes, struct iov_iter *i);
168 : void iov_iter_advance(struct iov_iter *i, size_t bytes);
169 : void iov_iter_revert(struct iov_iter *i, size_t bytes);
170 : size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
171 : size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes);
172 : size_t iov_iter_single_seg_count(const struct iov_iter *i);
173 : size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
174 : struct iov_iter *i);
175 : size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
176 : struct iov_iter *i);
177 :
178 : size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
179 : size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
180 : size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
181 :
182 : static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset,
183 : size_t bytes, struct iov_iter *i)
184 : {
185 0 : return copy_page_to_iter(&folio->page, offset, bytes, i);
186 : }
187 : size_t copy_page_to_iter_nofault(struct page *page, unsigned offset,
188 : size_t bytes, struct iov_iter *i);
189 :
190 : static __always_inline __must_check
191 : size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
192 : {
193 0 : if (check_copy_size(addr, bytes, true))
194 0 : return _copy_to_iter(addr, bytes, i);
195 : return 0;
196 : }
197 :
198 : static __always_inline __must_check
199 : size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
200 : {
201 0 : if (check_copy_size(addr, bytes, false))
202 0 : return _copy_from_iter(addr, bytes, i);
203 : return 0;
204 : }
205 :
206 : static __always_inline __must_check
207 : bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
208 : {
209 0 : size_t copied = copy_from_iter(addr, bytes, i);
210 0 : if (likely(copied == bytes))
211 : return true;
212 0 : iov_iter_revert(i, copied);
213 : return false;
214 : }
215 :
216 : static __always_inline __must_check
217 : size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
218 : {
219 : if (check_copy_size(addr, bytes, false))
220 : return _copy_from_iter_nocache(addr, bytes, i);
221 : return 0;
222 : }
223 :
224 : static __always_inline __must_check
225 : bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
226 : {
227 : size_t copied = copy_from_iter_nocache(addr, bytes, i);
228 : if (likely(copied == bytes))
229 : return true;
230 : iov_iter_revert(i, copied);
231 : return false;
232 : }
233 :
234 : #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
235 : /*
236 : * Note, users like pmem that depend on the stricter semantics of
237 : * _copy_from_iter_flushcache() than _copy_from_iter_nocache() must check for
238 : * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
239 : * destination is flushed from the cache on return.
240 : */
241 : size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
242 : #else
243 : #define _copy_from_iter_flushcache _copy_from_iter_nocache
244 : #endif
245 :
246 : #ifdef CONFIG_ARCH_HAS_COPY_MC
247 : size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
248 : static inline void iov_iter_set_copy_mc(struct iov_iter *i)
249 : {
250 : i->copy_mc = true;
251 : }
252 :
253 : static inline bool iov_iter_is_copy_mc(const struct iov_iter *i)
254 : {
255 : return i->copy_mc;
256 : }
257 : #else
258 : #define _copy_mc_to_iter _copy_to_iter
259 : static inline void iov_iter_set_copy_mc(struct iov_iter *i) { }
260 : static inline bool iov_iter_is_copy_mc(const struct iov_iter *i)
261 : {
262 : return false;
263 : }
264 : #endif
265 :
266 : size_t iov_iter_zero(size_t bytes, struct iov_iter *);
267 : bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
268 : unsigned len_mask);
269 : unsigned long iov_iter_alignment(const struct iov_iter *i);
270 : unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
271 : void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
272 : unsigned long nr_segs, size_t count);
273 : void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec,
274 : unsigned long nr_segs, size_t count);
275 : void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
276 : unsigned long nr_segs, size_t count);
277 : void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
278 : void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
279 : loff_t start, size_t count);
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_alloc2(struct iov_iter *i, struct page ***pages,
283 : size_t maxsize, size_t *start);
284 : int iov_iter_npages(const struct iov_iter *i, int maxpages);
285 : void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state);
286 :
287 : const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
288 :
289 : static inline size_t iov_iter_count(const struct iov_iter *i)
290 : {
291 : return i->count;
292 : }
293 :
294 : /*
295 : * Cap the iov_iter by given limit; note that the second argument is
296 : * *not* the new size - it's upper limit for such. Passing it a value
297 : * greater than the amount of data in iov_iter is fine - it'll just do
298 : * nothing in that case.
299 : */
300 : static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
301 : {
302 : /*
303 : * count doesn't have to fit in size_t - comparison extends both
304 : * operands to u64 here and any value that would be truncated by
305 : * conversion in assignement is by definition greater than all
306 : * values of size_t, including old i->count.
307 : */
308 0 : if (i->count > count)
309 0 : i->count = count;
310 : }
311 :
312 : /*
313 : * reexpand a previously truncated iterator; count must be no more than how much
314 : * we had shrunk it.
315 : */
316 : static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
317 : {
318 0 : i->count = count;
319 : }
320 :
321 : static inline int
322 : iov_iter_npages_cap(struct iov_iter *i, int maxpages, size_t max_bytes)
323 : {
324 : size_t shorted = 0;
325 : int npages;
326 :
327 : if (iov_iter_count(i) > max_bytes) {
328 : shorted = iov_iter_count(i) - max_bytes;
329 : iov_iter_truncate(i, max_bytes);
330 : }
331 : npages = iov_iter_npages(i, maxpages);
332 : if (shorted)
333 : iov_iter_reexpand(i, iov_iter_count(i) + shorted);
334 :
335 : return npages;
336 : }
337 :
338 : struct csum_state {
339 : __wsum csum;
340 : size_t off;
341 : };
342 :
343 : size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csstate, struct iov_iter *i);
344 : size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
345 :
346 : static __always_inline __must_check
347 : bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
348 : __wsum *csum, struct iov_iter *i)
349 : {
350 : size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
351 : if (likely(copied == bytes))
352 : return true;
353 : iov_iter_revert(i, copied);
354 : return false;
355 : }
356 : size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
357 : struct iov_iter *i);
358 :
359 : struct iovec *iovec_from_user(const struct iovec __user *uvector,
360 : unsigned long nr_segs, unsigned long fast_segs,
361 : struct iovec *fast_iov, bool compat);
362 : ssize_t import_iovec(int type, const struct iovec __user *uvec,
363 : unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
364 : struct iov_iter *i);
365 : ssize_t __import_iovec(int type, const struct iovec __user *uvec,
366 : unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
367 : struct iov_iter *i, bool compat);
368 : int import_single_range(int type, void __user *buf, size_t len,
369 : struct iovec *iov, struct iov_iter *i);
370 : int import_ubuf(int type, void __user *buf, size_t len, struct iov_iter *i);
371 :
372 0 : static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
373 : void __user *buf, size_t count)
374 : {
375 0 : WARN_ON(direction & ~(READ | WRITE));
376 0 : *i = (struct iov_iter) {
377 : .iter_type = ITER_UBUF,
378 : .copy_mc = false,
379 : .user_backed = true,
380 : .data_source = direction,
381 : .ubuf = buf,
382 : .count = count,
383 : .nr_segs = 1
384 : };
385 0 : }
386 : /* Flags for iov_iter_get/extract_pages*() */
387 : /* Allow P2PDMA on the extracted pages */
388 : #define ITER_ALLOW_P2PDMA ((__force iov_iter_extraction_t)0x01)
389 :
390 : ssize_t iov_iter_extract_pages(struct iov_iter *i, struct page ***pages,
391 : size_t maxsize, unsigned int maxpages,
392 : iov_iter_extraction_t extraction_flags,
393 : size_t *offset0);
394 :
395 : /**
396 : * iov_iter_extract_will_pin - Indicate how pages from the iterator will be retained
397 : * @iter: The iterator
398 : *
399 : * Examine the iterator and indicate by returning true or false as to how, if
400 : * at all, pages extracted from the iterator will be retained by the extraction
401 : * function.
402 : *
403 : * %true indicates that the pages will have a pin placed in them that the
404 : * caller must unpin. This is must be done for DMA/async DIO to force fork()
405 : * to forcibly copy a page for the child (the parent must retain the original
406 : * page).
407 : *
408 : * %false indicates that no measures are taken and that it's up to the caller
409 : * to retain the pages.
410 : */
411 : static inline bool iov_iter_extract_will_pin(const struct iov_iter *iter)
412 : {
413 0 : return user_backed_iter(iter);
414 : }
415 :
416 : struct sg_table;
417 : ssize_t extract_iter_to_sg(struct iov_iter *iter, size_t len,
418 : struct sg_table *sgtable, unsigned int sg_max,
419 : iov_iter_extraction_t extraction_flags);
420 :
421 : #endif
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