LXR RHEL5/crypto/scatterwalk.c

   1/*
   2 * Cryptographic API.
   3 *
   4 * Cipher operations.
   5 *
   6 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
   7 *               2002 Adam J. Richter <adam@yggdrasil.com>
   8 *               2004 Jean-Luc Cooke <jlcooke@certainkey.com>
   9 *
  10 * This program is free software; you can redistribute it and/or modify it
  11 * under the terms of the GNU General Public License as published by the Free
  12 * Software Foundation; either version 2 of the License, or (at your option)
  13 * any later version.
  14 *
  15 */
  16#include <linux/kernel.h>
  17#include <linux/mm.h>
  18#include <linux/pagemap.h>
  19#include <linux/highmem.h>
  20#include <asm/scatterlist.h>
  21#include "internal.h"
  22#include "scatterwalk.h"
  23
  24enum km_type crypto_km_types[] = {
  25        KM_USER0,
  26        KM_USER1,
  27        KM_SOFTIRQ0,
  28        KM_SOFTIRQ1,
  29};
  30
  31static void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
  32{
  33        if (out)
  34                memcpy(sgdata, buf, nbytes);
  35        else
  36                memcpy(buf, sgdata, nbytes);
  37}
  38
  39void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg)
  40{
  41        unsigned int rest_of_page;
  42
  43        walk->sg = sg;
  44
  45        walk->page = sg->page;
  46        walk->len_this_segment = sg->length;
  47
  48        BUG_ON(!sg->length);
  49
  50        rest_of_page = PAGE_CACHE_SIZE - (sg->offset & (PAGE_CACHE_SIZE - 1));
  51        walk->len_this_page = min(sg->length, rest_of_page);
  52        walk->offset = sg->offset;
  53}
  54
  55void scatterwalk_map(struct scatter_walk *walk, int out)
  56{
  57        walk->data = crypto_kmap(walk->page, out) + walk->offset;
  58}
  59
  60static inline void scatterwalk_unmap(struct scatter_walk *walk, int out)
  61{
  62        /* walk->data may be pointing the first byte of the next page;
  63           however, we know we transfered at least one byte.  So,
  64           walk->data - 1 will be a virtual address in the mapped page. */
  65        crypto_kunmap(walk->data - 1, out);
  66}
  67
  68static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
  69                                 unsigned int more)
  70{
  71        if (out)
  72                flush_dcache_page(walk->page);
  73
  74        if (more) {
  75                walk->len_this_segment -= walk->len_this_page;
  76
  77                if (walk->len_this_segment) {
  78                        walk->page++;
  79                        walk->len_this_page = min(walk->len_this_segment,
  80                                                  (unsigned)PAGE_CACHE_SIZE);
  81                        walk->offset = 0;
  82                }
  83                else
  84                        scatterwalk_start(walk, sg_next(walk->sg));
  85        }
  86}
  87
  88void scatterwalk_done(struct scatter_walk *walk, int out, int more)
  89{
  90        scatterwalk_unmap(walk, out);
  91        if (walk->len_this_page == 0 || !more)
  92                scatterwalk_pagedone(walk, out, more);
  93}
  94
  95/*
  96 * Do not call this unless the total length of all of the fragments
  97 * has been verified as multiple of the block size.
  98 */
  99int scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
 100                           size_t nbytes, int out)
 101{
 102        while (nbytes > walk->len_this_page) {
 103                memcpy_dir(buf, walk->data, walk->len_this_page, out);
 104                buf += walk->len_this_page;
 105                nbytes -= walk->len_this_page;
 106
 107                scatterwalk_unmap(walk, out);
 108                scatterwalk_pagedone(walk, out, 1);
 109                scatterwalk_map(walk, out);
 110        }
 111
 112        memcpy_dir(buf, walk->data, nbytes, out);
 113        return nbytes;
 114}
 115