include/linux/uio.h

   1 /*
   2  *      Berkeley style UIO structures   -       Alan Cox 1994.
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  */
   9 #ifndef __LINUX_UIO_H
  10 #define __LINUX_UIO_H
  11
  12 #include <linux/kernel.h>
  13 #include <uapi/linux/uio.h>
  14
  15 struct page;
  16 struct pipe_inode_info;
  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 {
  24         ITER_IOVEC = 0,
  25         ITER_KVEC = 2,
  26         ITER_BVEC = 4,
  27         ITER_PIPE = 8,
  28 };
  29
  30 struct iov_iter {
  31         int type;
  32         size_t iov_offset;
  33         size_t count;
  34         union {
  35                 const struct iovec *iov;
  36                 const struct kvec *kvec;
  37                 const struct bio_vec *bvec;
  38                 struct pipe_inode_info *pipe;
  39         };
  40         union {
  41                 unsigned long nr_segs;
  42                 struct {
  43                         int idx;
  44                         int start_idx;
  45                 };
  46         };
  47 };
  48
  49 /*
  50  * Total number of bytes covered by an iovec.
  51  *
  52  * NOTE that it is not safe to use this function until all the iovec's
  53  * segment lengths have been validated.  Because the individual lengths can
  54  * overflow a size_t when added together.
  55  */
  56 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
  57 {
  58         unsigned long seg;
  59         size_t ret = 0;
  60
  61         for (seg = 0; seg < nr_segs; seg++)
  62                 ret += iov[seg].iov_len;
  63         return ret;
  64 }
  65
  66 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
  67 {
  68         return (struct iovec) {
  69                 .iov_base = iter->iov->iov_base + iter->iov_offset,
  70                 .iov_len = min(iter->count,
  71                                iter->iov->iov_len - iter->iov_offset),
  72         };
  73 }
  74
  75 #define iov_for_each(iov, iter, start)                          \
  76         if (!((start).type & (ITER_BVEC | ITER_PIPE)))          \
  77         for (iter = (start);                                    \
  78              (iter).count &&                                    \
  79              ((iov = iov_iter_iovec(&(iter))), 1);              \
  80              iov_iter_advance(&(iter), (iov).iov_len))
  81
  82 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
  83
  84 size_t iov_iter_copy_from_user_atomic(struct page *page,
  85                 struct iov_iter *i, unsigned long offset, size_t bytes);
  86 void iov_iter_advance(struct iov_iter *i, size_t bytes);
  87 void iov_iter_revert(struct iov_iter *i, size_t bytes);
  88 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
  89 size_t iov_iter_single_seg_count(const struct iov_iter *i);
  90 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
  91                          struct iov_iter *i);
  92 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
  93                          struct iov_iter *i);
  94 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
  95 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
  96 bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i);
  97 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
  98 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
  99 /*
 100  * Note, users like pmem that depend on the stricter semantics of
 101  * copy_from_iter_flushcache() than copy_from_iter_nocache() must check for
 102  * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
 103  * destination is flushed from the cache on return.
 104  */
 105 size_t copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
 106 #else
 107 static inline size_t copy_from_iter_flushcache(void *addr, size_t bytes,
 108                                        struct iov_iter *i)
 109 {
 110         return copy_from_iter_nocache(addr, bytes, i);
 111 }
 112 #endif
 113 bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i);
 114 size_t iov_iter_zero(size_t bytes, struct iov_iter *);
 115 unsigned long iov_iter_alignment(const struct iov_iter *i);
 116 unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
 117 void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
 118                         unsigned long nr_segs, size_t count);
 119 void iov_iter_kvec(struct iov_iter *i, int direction, const struct kvec *kvec,
 120                         unsigned long nr_segs, size_t count);
 121 void iov_iter_bvec(struct iov_iter *i, int direction, const struct bio_vec *bvec,
 122                         unsigned long nr_segs, size_t count);
 123 void iov_iter_pipe(struct iov_iter *i, int direction, struct pipe_inode_info *pipe,
 124                         size_t count);
 125 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
 126                         size_t maxsize, unsigned maxpages, size_t *start);
 127 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
 128                         size_t maxsize, size_t *start);
 129 int iov_iter_npages(const struct iov_iter *i, int maxpages);
 130
 131 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
 132
 133 static inline size_t iov_iter_count(const struct iov_iter *i)
 134 {
 135         return i->count;
 136 }
 137
 138 static inline bool iter_is_iovec(const struct iov_iter *i)
 139 {
 140         return !(i->type & (ITER_BVEC | ITER_KVEC | ITER_PIPE));
 141 }
 142
 143 /*
 144  * Get one of READ or WRITE out of iter->type without any other flags OR'd in
 145  * with it.
 146  *
 147  * The ?: is just for type safety.
 148  */
 149 #define iov_iter_rw(i) ((0 ? (struct iov_iter *)0 : (i))->type & (READ | WRITE))
 150
 151 /*
 152  * Cap the iov_iter by given limit; note that the second argument is
 153  * *not* the new size - it's upper limit for such.  Passing it a value
 154  * greater than the amount of data in iov_iter is fine - it'll just do
 155  * nothing in that case.
 156  */
 157 static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
 158 {
 159         /*
 160          * count doesn't have to fit in size_t - comparison extends both
 161          * operands to u64 here and any value that would be truncated by
 162          * conversion in assignement is by definition greater than all
 163          * values of size_t, including old i->count.
 164          */
 165         if (i->count > count)
 166                 i->count = count;
 167 }
 168
 169 /*
 170  * reexpand a previously truncated iterator; count must be no more than how much
 171  * we had shrunk it.
 172  */
 173 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
 174 {
 175         i->count = count;
 176 }
 177 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
 178 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
 179 bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
 180
 181 int import_iovec(int type, const struct iovec __user * uvector,
 182                  unsigned nr_segs, unsigned fast_segs,
 183                  struct iovec **iov, struct iov_iter *i);
 184
 185 #ifdef CONFIG_COMPAT
 186 struct compat_iovec;
 187 int compat_import_iovec(int type, const struct compat_iovec __user * uvector,
 188                  unsigned nr_segs, unsigned fast_segs,
 189                  struct iovec **iov, struct iov_iter *i);
 190 #endif
 191
 192 int import_single_range(int type, void __user *buf, size_t len,
 193                  struct iovec *iov, struct iov_iter *i);
 194
 195 #endif