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 if (iter->iter_type == ITER_UBUF) 96 return (const struct iovec *) &iter->__ubuf_iovec; 97 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 state->iov_offset = iter->iov_offset; 112 state->count = iter->count; 113 state->nr_segs = iter->nr_segs; 114 } 115 116 static inline bool iter_is_ubuf(const struct iov_iter *i) 117 { 118 return iov_iter_type(i) == ITER_UBUF; 119 } 120 121 static inline bool iter_is_iovec(const struct iov_iter *i) 122 { 123 return iov_iter_type(i) == ITER_IOVEC; 124 } 125 126 static inline bool iov_iter_is_kvec(const struct iov_iter *i) 127 { 128 return iov_iter_type(i) == ITER_KVEC; 129 } 130 131 static inline bool iov_iter_is_bvec(const struct iov_iter *i) 132 { 133 return iov_iter_type(i) == ITER_BVEC; 134 } 135 136 static inline bool iov_iter_is_pipe(const struct iov_iter *i) 137 { 138 return iov_iter_type(i) == ITER_PIPE; 139 } 140 141 static inline bool iov_iter_is_discard(const struct iov_iter *i) 142 { 143 return iov_iter_type(i) == ITER_DISCARD; 144 } 145 146 static inline bool iov_iter_is_xarray(const struct iov_iter *i) 147 { 148 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 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 if (check_copy_size(addr, bytes, true)) 206 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 if (check_copy_size(addr, bytes, false)) 214 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 size_t copied = copy_from_iter(addr, bytes, i); 222 if (likely(copied == bytes)) 223 return true; 224 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 if (i->count > count) 329 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 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 static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction, 393 void __user *buf, size_t count) 394 { 395 WARN_ON(direction & ~(READ | WRITE)); 396 *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 } 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 437