LXR linux/drivers/staging/rtl8192u/ieee80211/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 "kmap_types.h"
  17
  18#include <linux/kernel.h>
  19#include <linux/mm.h>
  20#include <linux/pagemap.h>
  21#include <linux/highmem.h>
  22#include <asm/scatterlist.h>
  23#include "internal.h"
  24#include "scatterwalk.h"
  25
  26enum km_type crypto_km_types[] = {
  27        KM_USER0,
  28        KM_USER1,
  29        KM_SOFTIRQ0,
  30        KM_SOFTIRQ1,
  31};
  32
  33void *scatterwalk_whichbuf(struct scatter_walk *walk, unsigned int nbytes, void *scratch)
  34{
  35        if (nbytes <= walk->len_this_page &&
  36            (((unsigned long)walk->data) & (PAGE_CACHE_SIZE - 1)) + nbytes <=
  37            PAGE_CACHE_SIZE)
  38                return walk->data;
  39        else
  40                return scratch;
  41}
  42
  43static void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
  44{
  45        if (out)
  46                memcpy(sgdata, buf, nbytes);
  47        else
  48                memcpy(buf, sgdata, nbytes);
  49}
  50
  51void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg)
  52{
  53        unsigned int rest_of_page;
  54
  55        walk->sg = sg;
  56
  57        walk->page = sg->page;
  58        walk->len_this_segment = sg->length;
  59
  60        rest_of_page = PAGE_CACHE_SIZE - (sg->offset & (PAGE_CACHE_SIZE - 1));
  61        walk->len_this_page = min(sg->length, rest_of_page);
  62        walk->offset = sg->offset;
  63}
  64
  65void scatterwalk_map(struct scatter_walk *walk, int out)
  66{
  67        walk->data = crypto_kmap(walk->page, out) + walk->offset;
  68}
  69
  70static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
  71                                 unsigned int more)
  72{
  73        /* walk->data may be pointing the first byte of the next page;
  74           however, we know we transfered at least one byte.  So,
  75           walk->data - 1 will be a virtual address in the mapped page. */
  76
  77        if (out)
  78                flush_dcache_page(walk->page);
  79
  80        if (more) {
  81                walk->len_this_segment -= walk->len_this_page;
  82
  83                if (walk->len_this_segment) {
  84                        walk->page++;
  85                        walk->len_this_page = min(walk->len_this_segment,
  86                                                  (unsigned)PAGE_CACHE_SIZE);
  87                        walk->offset = 0;
  88                }
  89                else
  90                        scatterwalk_start(walk, sg_next(walk->sg));
  91        }
  92}
  93
  94void scatterwalk_done(struct scatter_walk *walk, int out, int more)
  95{
  96        crypto_kunmap(walk->data, out);
  97        if (walk->len_this_page == 0 || !more)
  98                scatterwalk_pagedone(walk, out, more);
  99}
 100
 101/*
 102 * Do not call this unless the total length of all of the fragments
 103 * has been verified as multiple of the block size.
 104 */
 105int scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
 106                           size_t nbytes, int out)
 107{
 108        if (buf != walk->data) {
 109                while (nbytes > walk->len_this_page) {
 110                        memcpy_dir(buf, walk->data, walk->len_this_page, out);
 111                        buf += walk->len_this_page;
 112                        nbytes -= walk->len_this_page;
 113
 114                        crypto_kunmap(walk->data, out);
 115                        scatterwalk_pagedone(walk, out, 1);
 116                        scatterwalk_map(walk, out);
 117                }
 118
 119                memcpy_dir(buf, walk->data, nbytes, out);
 120        }
 121
 122        walk->offset += nbytes;
 123        walk->len_this_page -= nbytes;
 124        walk->len_this_segment -= nbytes;
 125        return 0;
 126}
 127