include/crypto/scatterwalk.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * Cryptographic scatter and gather helpers.
   4  *
   5  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
   6  * Copyright (c) 2002 Adam J. Richter <adam@yggdrasil.com>
   7  * Copyright (c) 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
   8  * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
   9  */
  10
  11 #ifndef _CRYPTO_SCATTERWALK_H
  12 #define _CRYPTO_SCATTERWALK_H
  13
  14 #include <crypto/algapi.h>
  15
  16 #include <linux/highmem.h>
  17 #include <linux/mm.h>
  18 #include <linux/scatterlist.h>
  19
  20 static inline void scatterwalk_crypto_chain(struct scatterlist *head,
  21                                             struct scatterlist *sg, int num)
  22 {
  23         if (sg)
  24                 sg_chain(head, num, sg);
  25         else
  26                 sg_mark_end(head);
  27 }
  28
  29 static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
  30 {
  31         unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
  32         unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
  33         return len_this_page > len ? len : len_this_page;
  34 }
  35
  36 static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
  37                                              unsigned int nbytes)
  38 {
  39         unsigned int len_this_page = scatterwalk_pagelen(walk);
  40         return nbytes > len_this_page ? len_this_page : nbytes;
  41 }
  42
  43 static inline void scatterwalk_advance(struct scatter_walk *walk,
  44                                        unsigned int nbytes)
  45 {
  46         walk->offset += nbytes;
  47 }
  48
  49 static inline struct page *scatterwalk_page(struct scatter_walk *walk)
  50 {
  51         return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
  52 }
  53
  54 static inline void scatterwalk_unmap(void *vaddr)
  55 {
  56         kunmap_local(vaddr);
  57 }
  58
  59 static inline void scatterwalk_start(struct scatter_walk *walk,
  60                                      struct scatterlist *sg)
  61 {
  62         walk->sg = sg;
  63         walk->offset = sg->offset;
  64 }
  65
  66 static inline void *scatterwalk_map(struct scatter_walk *walk)
  67 {
  68         return kmap_local_page(scatterwalk_page(walk)) +
  69                offset_in_page(walk->offset);
  70 }
  71
  72 static inline void scatterwalk_pagedone(struct scatter_walk *walk, int out,
  73                                         unsigned int more)
  74 {
  75         if (out) {
  76                 struct page *page;
  77
  78                 page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
  79                 flush_dcache_page(page);
  80         }
  81
  82         if (more && walk->offset >= walk->sg->offset + walk->sg->length)
  83                 scatterwalk_start(walk, sg_next(walk->sg));
  84 }
  85
  86 static inline void scatterwalk_done(struct scatter_walk *walk, int out,
  87                                     int more)
  88 {
  89         if (!more || walk->offset >= walk->sg->offset + walk->sg->length ||
  90             !(walk->offset & (PAGE_SIZE - 1)))
  91                 scatterwalk_pagedone(walk, out, more);
  92 }
  93
  94 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
  95                             size_t nbytes, int out);
  96
  97 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
  98                               unsigned int start, unsigned int nbytes, int out);
  99
 100 struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
 101                                      struct scatterlist *src,
 102                                      unsigned int len);
 103
 104 #endif  /* _CRYPTO_SCATTERWALK_H */