linux/include/crypto/scatterwalk.h
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   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 <asm/kmap_types.h>
  20#include <crypto/algapi.h>
  21#include <linux/hardirq.h>
  22#include <linux/highmem.h>
  23#include <linux/kernel.h>
  24#include <linux/mm.h>
  25#include <linux/scatterlist.h>
  26#include <linux/sched.h>
  27
  28static inline void crypto_yield(u32 flags)
  29{
  30        if (flags & CRYPTO_TFM_REQ_MAY_SLEEP)
  31                cond_resched();
  32}
  33
  34static inline void scatterwalk_sg_chain(struct scatterlist *sg1, int num,
  35                                        struct scatterlist *sg2)
  36{
  37        sg_set_page(&sg1[num - 1], (void *)sg2, 0, 0);
  38        sg1[num - 1].page_link &= ~0x02;
  39}
  40
  41static inline struct scatterlist *scatterwalk_sg_next(struct scatterlist *sg)
  42{
  43        if (sg_is_last(sg))
  44                return NULL;
  45
  46        return (++sg)->length ? sg : (void *)sg_page(sg);
  47}
  48
  49static inline void scatterwalk_crypto_chain(struct scatterlist *head,
  50                                            struct scatterlist *sg,
  51                                            int chain, int num)
  52{
  53        if (chain) {
  54                head->length += sg->length;
  55                sg = scatterwalk_sg_next(sg);
  56        }
  57
  58        if (sg)
  59                scatterwalk_sg_chain(head, num, sg);
  60        else
  61                sg_mark_end(head);
  62}
  63
  64static inline unsigned long scatterwalk_samebuf(struct scatter_walk *walk_in,
  65                                                struct scatter_walk *walk_out)
  66{
  67        return !(((sg_page(walk_in->sg) - sg_page(walk_out->sg)) << PAGE_SHIFT) +
  68                 (int)(walk_in->offset - walk_out->offset));
  69}
  70
  71static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
  72{
  73        unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
  74        unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
  75        return len_this_page > len ? len : len_this_page;
  76}
  77
  78static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
  79                                             unsigned int nbytes)
  80{
  81        unsigned int len_this_page = scatterwalk_pagelen(walk);
  82        return nbytes > len_this_page ? len_this_page : nbytes;
  83}
  84
  85static inline void scatterwalk_advance(struct scatter_walk *walk,
  86                                       unsigned int nbytes)
  87{
  88        walk->offset += nbytes;
  89}
  90
  91static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
  92                                               unsigned int alignmask)
  93{
  94        return !(walk->offset & alignmask);
  95}
  96
  97static inline struct page *scatterwalk_page(struct scatter_walk *walk)
  98{
  99        return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
 100}
 101
 102static inline void scatterwalk_unmap(void *vaddr)
 103{
 104        kunmap_atomic(vaddr);
 105}
 106
 107void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg);
 108void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
 109                            size_t nbytes, int out);
 110void *scatterwalk_map(struct scatter_walk *walk);
 111void scatterwalk_done(struct scatter_walk *walk, int out, int more);
 112
 113void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
 114                              unsigned int start, unsigned int nbytes, int out);
 115
 116#endif  /* _CRYPTO_SCATTERWALK_H */
 117
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