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 : struct kvec {
17 : void *iov_base; /* and that should *never* hold a userland pointer */
18 : size_t iov_len;
19 : };
20 :
21 : enum iter_type {
22 : /* iter types */
23 : ITER_IOVEC,
24 : ITER_KVEC,
25 : ITER_BVEC,
26 : ITER_PIPE,
27 : ITER_XARRAY,
28 : ITER_DISCARD,
29 : };
30 :
31 : struct iov_iter_state {
32 : size_t iov_offset;
33 : size_t count;
34 : unsigned long nr_segs;
35 : };
36 :
37 : struct iov_iter {
38 : u8 iter_type;
39 : bool nofault;
40 : bool data_source;
41 : size_t iov_offset;
42 : size_t count;
43 : union {
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;
49 : };
50 : union {
51 : unsigned long nr_segs;
52 : struct {
53 : unsigned int head;
54 : unsigned int start_head;
55 : };
56 : loff_t xarray_start;
57 : };
58 : };
59 :
60 : static inline enum iter_type iov_iter_type(const struct iov_iter *i)
61 : {
62 : return i->iter_type;
63 : }
64 :
65 : static inline void iov_iter_save_state(struct iov_iter *iter,
66 : struct iov_iter_state *state)
67 : {
68 0 : state->iov_offset = iter->iov_offset;
69 0 : state->count = iter->count;
70 0 : state->nr_segs = iter->nr_segs;
71 : }
72 :
73 : static inline bool iter_is_iovec(const struct iov_iter *i)
74 : {
75 0 : return iov_iter_type(i) == ITER_IOVEC;
76 : }
77 :
78 : static inline bool iov_iter_is_kvec(const struct iov_iter *i)
79 : {
80 0 : return iov_iter_type(i) == ITER_KVEC;
81 : }
82 :
83 : static inline bool iov_iter_is_bvec(const struct iov_iter *i)
84 : {
85 0 : return iov_iter_type(i) == ITER_BVEC;
86 : }
87 :
88 : static inline bool iov_iter_is_pipe(const struct iov_iter *i)
89 : {
90 0 : return iov_iter_type(i) == ITER_PIPE;
91 : }
92 :
93 : static inline bool iov_iter_is_discard(const struct iov_iter *i)
94 : {
95 0 : return iov_iter_type(i) == ITER_DISCARD;
96 : }
97 :
98 : static inline bool iov_iter_is_xarray(const struct iov_iter *i)
99 : {
100 0 : return iov_iter_type(i) == ITER_XARRAY;
101 : }
102 :
103 : static inline unsigned char iov_iter_rw(const struct iov_iter *i)
104 : {
105 : return i->data_source ? WRITE : READ;
106 : }
107 :
108 : /*
109 : * Total number of bytes covered by an iovec.
110 : *
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.
114 : */
115 : static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
116 : {
117 : unsigned long seg;
118 : size_t ret = 0;
119 :
120 : for (seg = 0; seg < nr_segs; seg++)
121 : ret += iov[seg].iov_len;
122 : return ret;
123 : }
124 :
125 : static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
126 : {
127 : return (struct iovec) {
128 0 : .iov_base = iter->iov->iov_base + iter->iov_offset,
129 0 : .iov_len = min(iter->count,
130 : iter->iov->iov_len - iter->iov_offset),
131 : };
132 : }
133 :
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,
142 : struct iov_iter *i);
143 : size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
144 : struct iov_iter *i);
145 :
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);
149 :
150 : static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset,
151 : size_t bytes, struct iov_iter *i)
152 : {
153 0 : return copy_page_to_iter(&folio->page, offset, bytes, i);
154 : }
155 :
156 : static __always_inline __must_check
157 : size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
158 : {
159 0 : if (unlikely(!check_copy_size(addr, bytes, true)))
160 : return 0;
161 : else
162 0 : return _copy_to_iter(addr, bytes, i);
163 : }
164 :
165 : static __always_inline __must_check
166 : size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
167 : {
168 0 : if (unlikely(!check_copy_size(addr, bytes, false)))
169 : return 0;
170 : else
171 0 : return _copy_from_iter(addr, bytes, i);
172 : }
173 :
174 : static __always_inline __must_check
175 : bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
176 : {
177 0 : size_t copied = copy_from_iter(addr, bytes, i);
178 0 : if (likely(copied == bytes))
179 : return true;
180 0 : iov_iter_revert(i, copied);
181 : return false;
182 : }
183 :
184 : static __always_inline __must_check
185 : size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
186 : {
187 : if (unlikely(!check_copy_size(addr, bytes, false)))
188 : return 0;
189 : else
190 : return _copy_from_iter_nocache(addr, bytes, i);
191 : }
192 :
193 : static __always_inline __must_check
194 : bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
195 : {
196 : size_t copied = copy_from_iter_nocache(addr, bytes, i);
197 : if (likely(copied == bytes))
198 : return true;
199 : iov_iter_revert(i, copied);
200 : return false;
201 : }
202 :
203 : #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
204 : /*
205 : * Note, users like pmem that depend on the stricter semantics of
206 : * _copy_from_iter_flushcache() than _copy_from_iter_nocache() must check for
207 : * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
208 : * destination is flushed from the cache on return.
209 : */
210 : size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
211 : #else
212 : #define _copy_from_iter_flushcache _copy_from_iter_nocache
213 : #endif
214 :
215 : #ifdef CONFIG_ARCH_HAS_COPY_MC
216 : size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
217 : #else
218 : #define _copy_mc_to_iter _copy_to_iter
219 : #endif
220 :
221 : size_t iov_iter_zero(size_t bytes, struct iov_iter *);
222 : unsigned long iov_iter_alignment(const struct iov_iter *i);
223 : unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
224 : void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
225 : unsigned long nr_segs, size_t count);
226 : void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec,
227 : unsigned long nr_segs, size_t count);
228 : void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
229 : unsigned long nr_segs, size_t count);
230 : void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
231 : size_t count);
232 : void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
233 : void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
234 : loff_t start, size_t count);
235 : ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
236 : size_t maxsize, unsigned maxpages, size_t *start);
237 : ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
238 : size_t maxsize, size_t *start);
239 : int iov_iter_npages(const struct iov_iter *i, int maxpages);
240 : void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state);
241 :
242 : const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
243 :
244 : static inline size_t iov_iter_count(const struct iov_iter *i)
245 : {
246 : return i->count;
247 : }
248 :
249 : /*
250 : * Cap the iov_iter by given limit; note that the second argument is
251 : * *not* the new size - it's upper limit for such. Passing it a value
252 : * greater than the amount of data in iov_iter is fine - it'll just do
253 : * nothing in that case.
254 : */
255 : static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
256 : {
257 : /*
258 : * count doesn't have to fit in size_t - comparison extends both
259 : * operands to u64 here and any value that would be truncated by
260 : * conversion in assignement is by definition greater than all
261 : * values of size_t, including old i->count.
262 : */
263 0 : if (i->count > count)
264 0 : i->count = count;
265 : }
266 :
267 : /*
268 : * reexpand a previously truncated iterator; count must be no more than how much
269 : * we had shrunk it.
270 : */
271 : static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
272 : {
273 0 : i->count = count;
274 : }
275 :
276 : static inline int
277 : iov_iter_npages_cap(struct iov_iter *i, int maxpages, size_t max_bytes)
278 : {
279 : size_t shorted = 0;
280 : int npages;
281 :
282 : if (iov_iter_count(i) > max_bytes) {
283 : shorted = iov_iter_count(i) - max_bytes;
284 : iov_iter_truncate(i, max_bytes);
285 : }
286 : npages = iov_iter_npages(i, INT_MAX);
287 : if (shorted)
288 : iov_iter_reexpand(i, iov_iter_count(i) + shorted);
289 :
290 : return npages;
291 : }
292 :
293 : struct csum_state {
294 : __wsum csum;
295 : size_t off;
296 : };
297 :
298 : size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csstate, struct iov_iter *i);
299 : size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
300 :
301 : static __always_inline __must_check
302 : bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
303 : __wsum *csum, struct iov_iter *i)
304 : {
305 : size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
306 : if (likely(copied == bytes))
307 : return true;
308 : iov_iter_revert(i, copied);
309 : return false;
310 : }
311 : size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
312 : struct iov_iter *i);
313 :
314 : struct iovec *iovec_from_user(const struct iovec __user *uvector,
315 : unsigned long nr_segs, unsigned long fast_segs,
316 : struct iovec *fast_iov, bool compat);
317 : ssize_t import_iovec(int type, const struct iovec __user *uvec,
318 : unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
319 : struct iov_iter *i);
320 : ssize_t __import_iovec(int type, const struct iovec __user *uvec,
321 : unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
322 : struct iov_iter *i, bool compat);
323 : int import_single_range(int type, void __user *buf, size_t len,
324 : struct iovec *iov, struct iov_iter *i);
325 :
326 : #endif
|
