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
  26 enum km_type crypto_km_types[] = {
  27         KM_USER0,
  28         KM_USER1,
  29         KM_SOFTIRQ0,
  30         KM_SOFTIRQ1,
  31 };
  32
  33 void *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
  43 static 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
  51 void 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
  65 void scatterwalk_map(struct scatter_walk *walk, int out)
  66 {
  67         walk->data = crypto_kmap(walk->page, out) + walk->offset;
  68 }
  69
  70 static 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 transferred 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
  94 void 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  */
 105 int 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 }