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/module.h>
  19 #include <linux/pagemap.h>
  20 #include <linux/highmem.h>
  21 #include <linux/scatterlist.h>
  22
  23 #include "internal.h"
  24 #include "scatterwalk.h"
  25
  26 enum km_type crypto_km_types[] = {
  27         KM_USER0,
  28         KM_USER1,
  29         KM_SOFTIRQ0,
  30         KM_SOFTIRQ1,
  31 };
  32 EXPORT_SYMBOL_GPL(crypto_km_types);
  33
  34 static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
  35 {
  36         void *src = out ? buf : sgdata;
  37         void *dst = out ? sgdata : buf;
  38
  39         memcpy(dst, src, nbytes);
  40 }
  41
  42 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg)
  43 {
  44         walk->sg = sg;
  45
  46         BUG_ON(!sg->length);
  47
  48         walk->offset = sg->offset;
  49 }
  50 EXPORT_SYMBOL_GPL(scatterwalk_start);
  51
  52 void *scatterwalk_map(struct scatter_walk *walk, int out)
  53 {
  54         return crypto_kmap(scatterwalk_page(walk), out) +
  55                offset_in_page(walk->offset);
  56 }
  57 EXPORT_SYMBOL_GPL(scatterwalk_map);
  58
  59 static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
  60                                  unsigned int more)
  61 {
  62         if (out)
  63                 flush_dcache_page(scatterwalk_page(walk));
  64
  65         if (more) {
  66                 walk->offset += PAGE_SIZE - 1;
  67                 walk->offset &= PAGE_MASK;
  68                 if (walk->offset >= walk->sg->offset + walk->sg->length)
  69                         scatterwalk_start(walk, sg_next(walk->sg));
  70         }
  71 }
  72
  73 void scatterwalk_done(struct scatter_walk *walk, int out, int more)
  74 {
  75         if (!offset_in_page(walk->offset) || !more)
  76                 scatterwalk_pagedone(walk, out, more);
  77 }
  78 EXPORT_SYMBOL_GPL(scatterwalk_done);
  79
  80 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
  81                             size_t nbytes, int out)
  82 {
  83         for (;;) {
  84                 unsigned int len_this_page = scatterwalk_pagelen(walk);
  85                 u8 *vaddr;
  86
  87                 if (len_this_page > nbytes)
  88                         len_this_page = nbytes;
  89
  90                 vaddr = scatterwalk_map(walk, out);
  91                 memcpy_dir(buf, vaddr, len_this_page, out);
  92                 scatterwalk_unmap(vaddr, out);
  93
  94                 if (nbytes == len_this_page)
  95                         break;
  96
  97                 buf += len_this_page;
  98                 nbytes -= len_this_page;
  99
 100                 scatterwalk_pagedone(walk, out, 1);
 101         }
 102
 103         scatterwalk_advance(walk, nbytes);
 104 }
 105 EXPORT_SYMBOL_GPL(scatterwalk_copychunks);