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 = 4,
  23         ITER_KVEC = 8,
  24         ITER_BVEC = 16,
  25         ITER_PIPE = 32,
  26         ITER_DISCARD = 64,
  27 };
  28
  29 struct iov_iter {
  30         /*
  31          * Bit 0 is the read/write bit, set if we're writing.
  32          * Bit 1 is the BVEC_FLAG_NO_REF bit, set if type is a bvec and
  33          * the caller isn't expecting to drop a page reference when done.
  34          */
  35         unsigned int type;
  36         size_t iov_offset;
  37         size_t count;
  38         union {
  39                 const struct iovec *iov;
  40                 const struct kvec *kvec;
  41                 const struct bio_vec *bvec;
  42                 struct pipe_inode_info *pipe;
  43         };
  44         union {
  45                 unsigned long nr_segs;
  46                 struct {
  47                         unsigned int head;
  48                         unsigned int start_head;
  49                 };
  50         };
  51 };
  52
  53 static inline enum iter_type iov_iter_type(const struct iov_iter *i)
  54 {
  55         return i->type & ~(READ | WRITE);
  56 }
  57
  58 static inline bool iter_is_iovec(const struct iov_iter *i)
  59 {
  60         return iov_iter_type(i) == ITER_IOVEC;
  61 }
  62
  63 static inline bool iov_iter_is_kvec(const struct iov_iter *i)
  64 {
  65         return iov_iter_type(i) == ITER_KVEC;
  66 }
  67
  68 static inline bool iov_iter_is_bvec(const struct iov_iter *i)
  69 {
  70         return iov_iter_type(i) == ITER_BVEC;
  71 }
  72
  73 static inline bool iov_iter_is_pipe(const struct iov_iter *i)
  74 {
  75         return iov_iter_type(i) == ITER_PIPE;
  76 }
  77
  78 static inline bool iov_iter_is_discard(const struct iov_iter *i)
  79 {
  80         return iov_iter_type(i) == ITER_DISCARD;
  81 }
  82
  83 static inline unsigned char iov_iter_rw(const struct iov_iter *i)
  84 {
  85         return i->type & (READ | WRITE);
  86 }
  87
  88 /*
  89  * Total number of bytes covered by an iovec.
  90  *
  91  * NOTE that it is not safe to use this function until all the iovec's
  92  * segment lengths have been validated.  Because the individual lengths can
  93  * overflow a size_t when added together.
  94  */
  95 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
  96 {
  97         unsigned long seg;
  98         size_t ret = 0;
  99
 100         for (seg = 0; seg < nr_segs; seg++)
 101                 ret += iov[seg].iov_len;
 102         return ret;
 103 }
 104
 105 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
 106 {
 107         return (struct iovec) {
 108                 .iov_base = iter->iov->iov_base + iter->iov_offset,
 109                 .iov_len = min(iter->count,
 110                                iter->iov->iov_len - iter->iov_offset),
 111         };
 112 }
 113
 114 size_t iov_iter_copy_from_user_atomic(struct page *page,
 115                 struct iov_iter *i, unsigned long offset, size_t bytes);
 116 void iov_iter_advance(struct iov_iter *i, size_t bytes);
 117 void iov_iter_revert(struct iov_iter *i, size_t bytes);
 118 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
 119 size_t iov_iter_single_seg_count(const struct iov_iter *i);
 120 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
 121                          struct iov_iter *i);
 122 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
 123                          struct iov_iter *i);
 124
 125 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
 126 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
 127 bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i);
 128 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
 129 bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i);
 130
 131 static __always_inline __must_check
 132 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
 133 {
 134         if (unlikely(!check_copy_size(addr, bytes, true)))
 135                 return 0;
 136         else
 137                 return _copy_to_iter(addr, bytes, i);
 138 }
 139
 140 static __always_inline __must_check
 141 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
 142 {
 143         if (unlikely(!check_copy_size(addr, bytes, false)))
 144                 return 0;
 145         else
 146                 return _copy_from_iter(addr, bytes, i);
 147 }
 148
 149 static __always_inline __must_check
 150 bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
 151 {
 152         if (unlikely(!check_copy_size(addr, bytes, false)))
 153                 return false;
 154         else
 155                 return _copy_from_iter_full(addr, bytes, i);
 156 }
 157
 158 static __always_inline __must_check
 159 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
 160 {
 161         if (unlikely(!check_copy_size(addr, bytes, false)))
 162                 return 0;
 163         else
 164                 return _copy_from_iter_nocache(addr, bytes, i);
 165 }
 166
 167 static __always_inline __must_check
 168 bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
 169 {
 170         if (unlikely(!check_copy_size(addr, bytes, false)))
 171                 return false;
 172         else
 173                 return _copy_from_iter_full_nocache(addr, bytes, i);
 174 }
 175
 176 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
 177 /*
 178  * Note, users like pmem that depend on the stricter semantics of
 179  * copy_from_iter_flushcache() than copy_from_iter_nocache() must check for
 180  * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
 181  * destination is flushed from the cache on return.
 182  */
 183 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
 184 #else
 185 #define _copy_from_iter_flushcache _copy_from_iter_nocache
 186 #endif
 187
 188 #ifdef CONFIG_ARCH_HAS_COPY_MC
 189 size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
 190 #else
 191 #define _copy_mc_to_iter _copy_to_iter
 192 #endif
 193
 194 static __always_inline __must_check
 195 size_t copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
 196 {
 197         if (unlikely(!check_copy_size(addr, bytes, false)))
 198                 return 0;
 199         else
 200                 return _copy_from_iter_flushcache(addr, bytes, i);
 201 }
 202
 203 static __always_inline __must_check
 204 size_t copy_mc_to_iter(void *addr, size_t bytes, struct iov_iter *i)
 205 {
 206         if (unlikely(!check_copy_size(addr, bytes, true)))
 207                 return 0;
 208         else
 209                 return _copy_mc_to_iter(addr, bytes, i);
 210 }
 211
 212 size_t iov_iter_zero(size_t bytes, struct iov_iter *);
 213 unsigned long iov_iter_alignment(const struct iov_iter *i);
 214 unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
 215 void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
 216                         unsigned long nr_segs, size_t count);
 217 void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec,
 218                         unsigned long nr_segs, size_t count);
 219 void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
 220                         unsigned long nr_segs, size_t count);
 221 void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
 222                         size_t count);
 223 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
 224 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
 225                         size_t maxsize, unsigned maxpages, size_t *start);
 226 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
 227                         size_t maxsize, size_t *start);
 228 int iov_iter_npages(const struct iov_iter *i, int maxpages);
 229
 230 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
 231
 232 static inline size_t iov_iter_count(const struct iov_iter *i)
 233 {
 234         return i->count;
 235 }
 236
 237 /*
 238  * Cap the iov_iter by given limit; note that the second argument is
 239  * *not* the new size - it's upper limit for such.  Passing it a value
 240  * greater than the amount of data in iov_iter is fine - it'll just do
 241  * nothing in that case.
 242  */
 243 static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
 244 {
 245         /*
 246          * count doesn't have to fit in size_t - comparison extends both
 247          * operands to u64 here and any value that would be truncated by
 248          * conversion in assignement is by definition greater than all
 249          * values of size_t, including old i->count.
 250          */
 251         if (i->count > count)
 252                 i->count = count;
 253 }
 254
 255 /*
 256  * reexpand a previously truncated iterator; count must be no more than how much
 257  * we had shrunk it.
 258  */
 259 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
 260 {
 261         i->count = count;
 262 }
 263 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csump, struct iov_iter *i);
 264 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
 265 bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
 266 size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
 267                 struct iov_iter *i);
 268
 269 struct iovec *iovec_from_user(const struct iovec __user *uvector,
 270                 unsigned long nr_segs, unsigned long fast_segs,
 271                 struct iovec *fast_iov, bool compat);
 272 ssize_t import_iovec(int type, const struct iovec __user *uvec,
 273                  unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
 274                  struct iov_iter *i);
 275 ssize_t __import_iovec(int type, const struct iovec __user *uvec,
 276                  unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
 277                  struct iov_iter *i, bool compat);
 278 int import_single_range(int type, void __user *buf, size_t len,
 279                  struct iovec *iov, struct iov_iter *i);
 280
 281 int iov_iter_for_each_range(struct iov_iter *i, size_t bytes,
 282                             int (*f)(struct kvec *vec, void *context),
 283                             void *context);
 284
 285 #endif