LXR linux/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
  24static inline void scatterwalk_crypto_chain(struct scatterlist *head,
  25                                            struct scatterlist *sg,
  26                                            int chain, int num)
  27{
  28        if (chain) {
  29                head->length += sg->length;
  30                sg = sg_next(sg);
  31        }
  32
  33        if (sg)
  34                sg_chain(head, num, sg);
  35        else
  36                sg_mark_end(head);
  37}
  38
  39static inline unsigned long scatterwalk_samebuf(struct scatter_walk *walk_in,
  40                                                struct scatter_walk *walk_out)
  41{
  42        return !(((sg_page(walk_in->sg) - sg_page(walk_out->sg)) << PAGE_SHIFT) +
  43                 (int)(walk_in->offset - walk_out->offset));
  44}
  45
  46static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
  47{
  48        unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
  49        unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
  50        return len_this_page > len ? len : len_this_page;
  51}
  52
  53static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
  54                                             unsigned int nbytes)
  55{
  56        unsigned int len_this_page = scatterwalk_pagelen(walk);
  57        return nbytes > len_this_page ? len_this_page : nbytes;
  58}
  59
  60static inline void scatterwalk_advance(struct scatter_walk *walk,
  61                                       unsigned int nbytes)
  62{
  63        walk->offset += nbytes;
  64}
  65
  66static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
  67                                               unsigned int alignmask)
  68{
  69        return !(walk->offset & alignmask);
  70}
  71
  72static inline struct page *scatterwalk_page(struct scatter_walk *walk)
  73{
  74        return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
  75}
  76
  77static inline void scatterwalk_unmap(void *vaddr)
  78{
  79        kunmap_atomic(vaddr);
  80}
  81
  82static inline void scatterwalk_start(struct scatter_walk *walk,
  83                                     struct scatterlist *sg)
  84{
  85        walk->sg = sg;
  86        walk->offset = sg->offset;
  87}
  88
  89static inline void *scatterwalk_map(struct scatter_walk *walk)
  90{
  91        return kmap_atomic(scatterwalk_page(walk)) +
  92               offset_in_page(walk->offset);
  93}
  94
  95static inline void scatterwalk_pagedone(struct scatter_walk *walk, int out,
  96                                        unsigned int more)
  97{
  98        if (out) {
  99                struct page *page;
 100
 101                page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
 102                /* Test ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE first as
 103                 * PageSlab cannot be optimised away per se due to
 104                 * use of volatile pointer.
 105                 */
 106                if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE && !PageSlab(page))
 107                        flush_dcache_page(page);
 108        }
 109
 110        if (more && walk->offset >= walk->sg->offset + walk->sg->length)
 111                scatterwalk_start(walk, sg_next(walk->sg));
 112}
 113
 114static inline void scatterwalk_done(struct scatter_walk *walk, int out,
 115                                    int more)
 116{
 117        if (!more || walk->offset >= walk->sg->offset + walk->sg->length ||
 118            !(walk->offset & (PAGE_SIZE - 1)))
 119                scatterwalk_pagedone(walk, out, more);
 120}
 121
 122void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
 123                            size_t nbytes, int out);
 124void *scatterwalk_map(struct scatter_walk *walk);
 125
 126void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
 127                              unsigned int start, unsigned int nbytes, int out);
 128
 129struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
 130                                     struct scatterlist *src,
 131                                     unsigned int len);
 132
 133#endif  /* _CRYPTO_SCATTERWALK_H */
 134