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 #include <linux/highmem.h>
  16 #include <linux/kernel.h>
  17 #include <linux/scatterlist.h>
  18
  19 static inline void scatterwalk_crypto_chain(struct scatterlist *head,
  20                                             struct scatterlist *sg, int num)
  21 {
  22         if (sg)
  23                 sg_chain(head, num, sg);
  24         else
  25                 sg_mark_end(head);
  26 }
  27
  28 static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
  29 {
  30         unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
  31         unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
  32         return len_this_page > len ? len : len_this_page;
  33 }
  34
  35 static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
  36                                              unsigned int nbytes)
  37 {
  38         unsigned int len_this_page = scatterwalk_pagelen(walk);
  39         return nbytes > len_this_page ? len_this_page : nbytes;
  40 }
  41
  42 static inline void scatterwalk_advance(struct scatter_walk *walk,
  43                                        unsigned int nbytes)
  44 {
  45         walk->offset += nbytes;
  46 }
  47
  48 static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
  49                                                unsigned int alignmask)
  50 {
  51         return !(walk->offset & alignmask);
  52 }
  53
  54 static inline struct page *scatterwalk_page(struct scatter_walk *walk)
  55 {
  56         return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
  57 }
  58
  59 static inline void scatterwalk_unmap(void *vaddr)
  60 {
  61         kunmap_atomic(vaddr);
  62 }
  63
  64 static inline void scatterwalk_start(struct scatter_walk *walk,
  65                                      struct scatterlist *sg)
  66 {
  67         walk->sg = sg;
  68         walk->offset = sg->offset;
  69 }
  70
  71 static inline void *scatterwalk_map(struct scatter_walk *walk)
  72 {
  73         return kmap_atomic(scatterwalk_page(walk)) +
  74                offset_in_page(walk->offset);
  75 }
  76
  77 static inline void scatterwalk_pagedone(struct scatter_walk *walk, int out,
  78                                         unsigned int more)
  79 {
  80         if (out) {
  81                 struct page *page;
  82
  83                 page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
  84                 /* Test ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE first as
  85                  * PageSlab cannot be optimised away per se due to
  86                  * use of volatile pointer.
  87                  */
  88                 if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE && !PageSlab(page))
  89                         flush_dcache_page(page);
  90         }
  91
  92         if (more && walk->offset >= walk->sg->offset + walk->sg->length)
  93                 scatterwalk_start(walk, sg_next(walk->sg));
  94 }
  95
  96 static inline void scatterwalk_done(struct scatter_walk *walk, int out,
  97                                     int more)
  98 {
  99         if (!more || walk->offset >= walk->sg->offset + walk->sg->length ||
 100             !(walk->offset & (PAGE_SIZE - 1)))
 101                 scatterwalk_pagedone(walk, out, more);
 102 }
 103
 104 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
 105                             size_t nbytes, int out);
 106 void *scatterwalk_map(struct scatter_walk *walk);
 107
 108 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
 109                               unsigned int start, unsigned int nbytes, int out);
 110
 111 struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
 112                                      struct scatterlist *src,
 113                                      unsigned int len);
 114
 115 #endif  /* _CRYPTO_SCATTERWALK_H */