include/crypto/scatterwalk.h

   1 /*
   2  * Cryptographic scatter and gather helpers.
   3  *
   4  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
   5  * Copyright (c) 2002 Adam J. Richter <adam@yggdrasil.com>
   6  * Copyright (c) 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
   7  * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU General Public License as published by the Free
  11  * Software Foundation; either version 2 of the License, or (at your option)
  12  * any later version.
  13  *
  14  */
  15
  16 #ifndef _CRYPTO_SCATTERWALK_H
  17 #define _CRYPTO_SCATTERWALK_H
  18
  19 #include <crypto/algapi.h>
  20 #include <linux/highmem.h>
  21 #include <linux/kernel.h>
  22 #include <linux/scatterlist.h>
  23
  24 static inline void scatterwalk_crypto_chain(struct scatterlist *head,
  25                                             struct scatterlist *sg, int num)
  26 {
  27         if (sg)
  28                 sg_chain(head, num, sg);
  29         else
  30                 sg_mark_end(head);
  31 }
  32
  33 static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
  34 {
  35         unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
  36         unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
  37         return len_this_page > len ? len : len_this_page;
  38 }
  39
  40 static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
  41                                              unsigned int nbytes)
  42 {
  43         unsigned int len_this_page = scatterwalk_pagelen(walk);
  44         return nbytes > len_this_page ? len_this_page : nbytes;
  45 }
  46
  47 static inline void scatterwalk_advance(struct scatter_walk *walk,
  48                                        unsigned int nbytes)
  49 {
  50         walk->offset += nbytes;
  51 }
  52
  53 static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
  54                                                unsigned int alignmask)
  55 {
  56         return !(walk->offset & alignmask);
  57 }
  58
  59 static inline struct page *scatterwalk_page(struct scatter_walk *walk)
  60 {
  61         return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
  62 }
  63
  64 static inline void scatterwalk_unmap(void *vaddr)
  65 {
  66         kunmap_atomic(vaddr);
  67 }
  68
  69 static inline void scatterwalk_start(struct scatter_walk *walk,
  70                                      struct scatterlist *sg)
  71 {
  72         walk->sg = sg;
  73         walk->offset = sg->offset;
  74 }
  75
  76 static inline void *scatterwalk_map(struct scatter_walk *walk)
  77 {
  78         return kmap_atomic(scatterwalk_page(walk)) +
  79                offset_in_page(walk->offset);
  80 }
  81
  82 static inline void scatterwalk_pagedone(struct scatter_walk *walk, int out,
  83                                         unsigned int more)
  84 {
  85         if (out) {
  86                 struct page *page;
  87
  88                 page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
  89                 /* Test ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE first as
  90                  * PageSlab cannot be optimised away per se due to
  91                  * use of volatile pointer.
  92                  */
  93                 if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE && !PageSlab(page))
  94                         flush_dcache_page(page);
  95         }
  96
  97         if (more && walk->offset >= walk->sg->offset + walk->sg->length)
  98                 scatterwalk_start(walk, sg_next(walk->sg));
  99 }
 100
 101 static inline void scatterwalk_done(struct scatter_walk *walk, int out,
 102                                     int more)
 103 {
 104         if (!more || walk->offset >= walk->sg->offset + walk->sg->length ||
 105             !(walk->offset & (PAGE_SIZE - 1)))
 106                 scatterwalk_pagedone(walk, out, more);
 107 }
 108
 109 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
 110                             size_t nbytes, int out);
 111 void *scatterwalk_map(struct scatter_walk *walk);
 112
 113 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
 114                               unsigned int start, unsigned int nbytes, int out);
 115
 116 struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
 117                                      struct scatterlist *src,
 118                                      unsigned int len);
 119
 120 #endif  /* _CRYPTO_SCATTERWALK_H */