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 17 struct kvec { 18 void *iov_base; /* and that should *never* hold a userland pointer */ 19 size_t iov_len; 20 }; 21 22 enum { 23 ITER_IOVEC = 0, 24 ITER_KVEC = 2, 25 ITER_BVEC = 4, 26 }; 27 28 struct iov_iter { 29 int type; 30 size_t iov_offset; 31 size_t count; 32 union { 33 const struct iovec *iov; 34 const struct kvec *kvec; 35 const struct bio_vec *bvec; 36 }; 37 unsigned long nr_segs; 38 }; 39 40 /* 41 * Total number of bytes covered by an iovec. 42 * 43 * NOTE that it is not safe to use this function until all the iovec's 44 * segment lengths have been validated. Because the individual lengths can 45 * overflow a size_t when added together. 46 */ 47 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs) 48 { 49 unsigned long seg; 50 size_t ret = 0; 51 52 for (seg = 0; seg < nr_segs; seg++) 53 ret += iov[seg].iov_len; 54 return ret; 55 } 56 57 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter) 58 { 59 return (struct iovec) { 60 .iov_base = iter->iov->iov_base + iter->iov_offset, 61 .iov_len = min(iter->count, 62 iter->iov->iov_len - iter->iov_offset), 63 }; 64 } 65 66 #define iov_for_each(iov, iter, start) \ 67 if (!((start).type & ITER_BVEC)) \ 68 for (iter = (start); \ 69 (iter).count && \ 70 ((iov = iov_iter_iovec(&(iter))), 1); \ 71 iov_iter_advance(&(iter), (iov).iov_len)) 72 73 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to); 74 75 size_t iov_iter_copy_from_user_atomic(struct page *page, 76 struct iov_iter *i, unsigned long offset, size_t bytes); 77 void iov_iter_advance(struct iov_iter *i, size_t bytes); 78 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes); 79 int iov_iter_fault_in_multipages_readable(struct iov_iter *i, size_t bytes); 80 size_t iov_iter_single_seg_count(const struct iov_iter *i); 81 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, 82 struct iov_iter *i); 83 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, 84 struct iov_iter *i); 85 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i); 86 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i); 87 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i); 88 size_t iov_iter_zero(size_t bytes, struct iov_iter *); 89 unsigned long iov_iter_alignment(const struct iov_iter *i); 90 void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov, 91 unsigned long nr_segs, size_t count); 92 void iov_iter_kvec(struct iov_iter *i, int direction, const struct kvec *kvec, 93 unsigned long nr_segs, size_t count); 94 void iov_iter_bvec(struct iov_iter *i, int direction, const struct bio_vec *bvec, 95 unsigned long nr_segs, size_t count); 96 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages, 97 size_t maxsize, unsigned maxpages, size_t *start); 98 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages, 99 size_t maxsize, size_t *start); 100 int iov_iter_npages(const struct iov_iter *i, int maxpages); 101 102 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags); 103 104 static inline size_t iov_iter_count(struct iov_iter *i) 105 { 106 return i->count; 107 } 108 109 static inline bool iter_is_iovec(struct iov_iter *i) 110 { 111 return !(i->type & (ITER_BVEC | ITER_KVEC)); 112 } 113 114 /* 115 * Get one of READ or WRITE out of iter->type without any other flags OR'd in 116 * with it. 117 * 118 * The ?: is just for type safety. 119 */ 120 #define iov_iter_rw(i) ((0 ? (struct iov_iter *)0 : (i))->type & RW_MASK) 121 122 /* 123 * Cap the iov_iter by given limit; note that the second argument is 124 * *not* the new size - it's upper limit for such. Passing it a value 125 * greater than the amount of data in iov_iter is fine - it'll just do 126 * nothing in that case. 127 */ 128 static inline void iov_iter_truncate(struct iov_iter *i, u64 count) 129 { 130 /* 131 * count doesn't have to fit in size_t - comparison extends both 132 * operands to u64 here and any value that would be truncated by 133 * conversion in assignement is by definition greater than all 134 * values of size_t, including old i->count. 135 */ 136 if (i->count > count) 137 i->count = count; 138 } 139 140 /* 141 * reexpand a previously truncated iterator; count must be no more than how much 142 * we had shrunk it. 143 */ 144 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count) 145 { 146 i->count = count; 147 } 148 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum, struct iov_iter *i); 149 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i); 150 151 int import_iovec(int type, const struct iovec __user * uvector, 152 unsigned nr_segs, unsigned fast_segs, 153 struct iovec **iov, struct iov_iter *i); 154 155 #ifdef CONFIG_COMPAT 156 struct compat_iovec; 157 int compat_import_iovec(int type, const struct compat_iovec __user * uvector, 158 unsigned nr_segs, unsigned fast_segs, 159 struct iovec **iov, struct iov_iter *i); 160 #endif 161 162 int import_single_range(int type, void __user *buf, size_t len, 163 struct iovec *iov, struct iov_iter *i); 164 165 #endif 166