LXR linux/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
  19static 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
  28static 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
  35static 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
  42static inline void scatterwalk_advance(struct scatter_walk *walk,
  43                                       unsigned int nbytes)
  44{
  45        walk->offset += nbytes;
  46}
  47
  48static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
  49                                               unsigned int alignmask)
  50{
  51        return !(walk->offset & alignmask);
  52}
  53
  54static inline struct page *scatterwalk_page(struct scatter_walk *walk)
  55{
  56        return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
  57}
  58
  59static inline void scatterwalk_unmap(void *vaddr)
  60{
  61        kunmap_atomic(vaddr);
  62}
  63
  64static inline void scatterwalk_start(struct scatter_walk *walk,
  65                                     struct scatterlist *sg)
  66{
  67        walk->sg = sg;
  68        walk->offset = sg->offset;
  69}
  70
  71static inline void *scatterwalk_map(struct scatter_walk *walk)
  72{
  73        return kmap_atomic(scatterwalk_page(walk)) +
  74               offset_in_page(walk->offset);
  75}
  76
  77static 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
  96static 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
 104void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
 105                            size_t nbytes, int out);
 106void *scatterwalk_map(struct scatter_walk *walk);
 107
 108void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
 109                              unsigned int start, unsigned int nbytes, int out);
 110
 111struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
 112                                     struct scatterlist *src,
 113                                     unsigned int len);
 114
 115#endif  /* _CRYPTO_SCATTERWALK_H */
 116