include/linux/uio.h

   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 <uapi/linux/uio.h>
  11
  12 struct page;
  13 struct pipe_inode_info;
  14
  15 struct kvec {
  16         void *iov_base; /* and that should *never* hold a userland pointer */
  17         size_t iov_len;
  18 };
  19
  20 enum iter_type {
  21         /* iter types */
  22         ITER_IOVEC,
  23         ITER_KVEC,
  24         ITER_BVEC,
  25         ITER_PIPE,
  26         ITER_XARRAY,
  27         ITER_DISCARD,
  28 };
  29
  30 struct iov_iter_state {
  31         size_t iov_offset;
  32         size_t count;
  33         unsigned long nr_segs;
  34 };
  35
  36 struct iov_iter {
  37         u8 iter_type;
  38         bool data_source;
  39         size_t iov_offset;
  40         size_t count;
  41         union {
  42                 const struct iovec *iov;
  43                 const struct kvec *kvec;
  44                 const struct bio_vec *bvec;
  45                 struct xarray *xarray;
  46                 struct pipe_inode_info *pipe;
  47         };
  48         union {
  49                 unsigned long nr_segs;
  50                 struct {
  51                         unsigned int head;
  52                         unsigned int start_head;
  53                 };
  54                 loff_t xarray_start;
  55         };
  56 };
  57
  58 static inline enum iter_type iov_iter_type(const struct iov_iter *i)
  59 {
  60         return i->iter_type;
  61 }
  62
  63 static inline void iov_iter_save_state(struct iov_iter *iter,
  64                                        struct iov_iter_state *state)
  65 {
  66         state->iov_offset = iter->iov_offset;
  67         state->count = iter->count;
  68         state->nr_segs = iter->nr_segs;
  69 }
  70
  71 static inline bool iter_is_iovec(const struct iov_iter *i)
  72 {
  73         return iov_iter_type(i) == ITER_IOVEC;
  74 }
  75
  76 static inline bool iov_iter_is_kvec(const struct iov_iter *i)
  77 {
  78         return iov_iter_type(i) == ITER_KVEC;
  79 }
  80
  81 static inline bool iov_iter_is_bvec(const struct iov_iter *i)
  82 {
  83         return iov_iter_type(i) == ITER_BVEC;
  84 }
  85
  86 static inline bool iov_iter_is_pipe(const struct iov_iter *i)
  87 {
  88         return iov_iter_type(i) == ITER_PIPE;
  89 }
  90
  91 static inline bool iov_iter_is_discard(const struct iov_iter *i)
  92 {
  93         return iov_iter_type(i) == ITER_DISCARD;
  94 }
  95
  96 static inline bool iov_iter_is_xarray(const struct iov_iter *i)
  97 {
  98         return iov_iter_type(i) == ITER_XARRAY;
  99 }
 100
 101 static inline unsigned char iov_iter_rw(const struct iov_iter *i)
 102 {
 103         return i->data_source ? WRITE : READ;
 104 }
 105
 106 /*
 107  * Total number of bytes covered by an iovec.
 108  *
 109  * NOTE that it is not safe to use this function until all the iovec's
 110  * segment lengths have been validated.  Because the individual lengths can
 111  * overflow a size_t when added together.
 112  */
 113 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
 114 {
 115         unsigned long seg;
 116         size_t ret = 0;
 117
 118         for (seg = 0; seg < nr_segs; seg++)
 119                 ret += iov[seg].iov_len;
 120         return ret;
 121 }
 122
 123 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
 124 {
 125         return (struct iovec) {
 126                 .iov_base = iter->iov->iov_base + iter->iov_offset,
 127                 .iov_len = min(iter->count,
 128                                iter->iov->iov_len - iter->iov_offset),
 129         };
 130 }
 131
 132 size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
 133                                   size_t bytes, struct iov_iter *i);
 134 void iov_iter_advance(struct iov_iter *i, size_t bytes);
 135 void iov_iter_revert(struct iov_iter *i, size_t bytes);
 136 int iov_iter_fault_in_readable(const struct iov_iter *i, size_t bytes);
 137 size_t iov_iter_single_seg_count(const struct iov_iter *i);
 138 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
 139                          struct iov_iter *i);
 140 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
 141                          struct iov_iter *i);
 142
 143 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
 144 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
 145 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
 146
 147 static __always_inline __must_check
 148 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
 149 {
 150         if (unlikely(!check_copy_size(addr, bytes, true)))
 151                 return 0;
 152         else
 153                 return _copy_to_iter(addr, bytes, i);
 154 }
 155
 156 static __always_inline __must_check
 157 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
 158 {
 159         if (unlikely(!check_copy_size(addr, bytes, false)))
 160                 return 0;
 161         else
 162                 return _copy_from_iter(addr, bytes, i);
 163 }
 164
 165 static __always_inline __must_check
 166 bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
 167 {
 168         size_t copied = copy_from_iter(addr, bytes, i);
 169         if (likely(copied == bytes))
 170                 return true;
 171         iov_iter_revert(i, copied);
 172         return false;
 173 }
 174
 175 static __always_inline __must_check
 176 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
 177 {
 178         if (unlikely(!check_copy_size(addr, bytes, false)))
 179                 return 0;
 180         else
 181                 return _copy_from_iter_nocache(addr, bytes, i);
 182 }
 183
 184 static __always_inline __must_check
 185 bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
 186 {
 187         size_t copied = copy_from_iter_nocache(addr, bytes, i);
 188         if (likely(copied == bytes))
 189                 return true;
 190         iov_iter_revert(i, copied);
 191         return false;
 192 }
 193
 194 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
 195 /*
 196  * Note, users like pmem that depend on the stricter semantics of
 197  * copy_from_iter_flushcache() than copy_from_iter_nocache() must check for
 198  * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
 199  * destination is flushed from the cache on return.
 200  */
 201 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
 202 #else
 203 #define _copy_from_iter_flushcache _copy_from_iter_nocache
 204 #endif
 205
 206 #ifdef CONFIG_ARCH_HAS_COPY_MC
 207 size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
 208 #else
 209 #define _copy_mc_to_iter _copy_to_iter
 210 #endif
 211
 212 static __always_inline __must_check
 213 size_t copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
 214 {
 215         if (unlikely(!check_copy_size(addr, bytes, false)))
 216                 return 0;
 217         else
 218                 return _copy_from_iter_flushcache(addr, bytes, i);
 219 }
 220
 221 static __always_inline __must_check
 222 size_t copy_mc_to_iter(void *addr, size_t bytes, struct iov_iter *i)
 223 {
 224         if (unlikely(!check_copy_size(addr, bytes, true)))
 225                 return 0;
 226         else
 227                 return _copy_mc_to_iter(addr, bytes, i);
 228 }
 229
 230 size_t iov_iter_zero(size_t bytes, struct iov_iter *);
 231 unsigned long iov_iter_alignment(const struct iov_iter *i);
 232 unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
 233 void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
 234                         unsigned long nr_segs, size_t count);
 235 void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec,
 236                         unsigned long nr_segs, size_t count);
 237 void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
 238                         unsigned long nr_segs, size_t count);
 239 void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
 240                         size_t count);
 241 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
 242 void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
 243                      loff_t start, size_t count);
 244 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
 245                         size_t maxsize, unsigned maxpages, size_t *start);
 246 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
 247                         size_t maxsize, size_t *start);
 248 int iov_iter_npages(const struct iov_iter *i, int maxpages);
 249 void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state);
 250
 251 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
 252
 253 static inline size_t iov_iter_count(const struct iov_iter *i)
 254 {
 255         return i->count;
 256 }
 257
 258 /*
 259  * Cap the iov_iter by given limit; note that the second argument is
 260  * *not* the new size - it's upper limit for such.  Passing it a value
 261  * greater than the amount of data in iov_iter is fine - it'll just do
 262  * nothing in that case.
 263  */
 264 static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
 265 {
 266         /*
 267          * count doesn't have to fit in size_t - comparison extends both
 268          * operands to u64 here and any value that would be truncated by
 269          * conversion in assignement is by definition greater than all
 270          * values of size_t, including old i->count.
 271          */
 272         if (i->count > count)
 273                 i->count = count;
 274 }
 275
 276 /*
 277  * reexpand a previously truncated iterator; count must be no more than how much
 278  * we had shrunk it.
 279  */
 280 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
 281 {
 282         i->count = count;
 283 }
 284
 285 struct csum_state {
 286         __wsum csum;
 287         size_t off;
 288 };
 289
 290 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csstate, struct iov_iter *i);
 291 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
 292
 293 static __always_inline __must_check
 294 bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
 295                                   __wsum *csum, struct iov_iter *i)
 296 {
 297         size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
 298         if (likely(copied == bytes))
 299                 return true;
 300         iov_iter_revert(i, copied);
 301         return false;
 302 }
 303 size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
 304                 struct iov_iter *i);
 305
 306 struct iovec *iovec_from_user(const struct iovec __user *uvector,
 307                 unsigned long nr_segs, unsigned long fast_segs,
 308                 struct iovec *fast_iov, bool compat);
 309 ssize_t import_iovec(int type, const struct iovec __user *uvec,
 310                  unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
 311                  struct iov_iter *i);
 312 ssize_t __import_iovec(int type, const struct iovec __user *uvec,
 313                  unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
 314                  struct iov_iter *i, bool compat);
 315 int import_single_range(int type, void __user *buf, size_t len,
 316                  struct iovec *iov, struct iov_iter *i);
 317
 318 #endif