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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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/bug.h>
21#include <asm/scatterlist.h>
22#include "internal.h"
23#include "scatterwalk.h"
24
25enum km_type crypto_km_types[] = {
26 KM_USER0,
27 KM_USER1,
28 KM_SOFTIRQ0,
29 KM_SOFTIRQ1,
30};
31
32static void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
33{
34 if (out)
35 memcpy(sgdata, buf, nbytes);
36 else
37 memcpy(buf, sgdata, nbytes);
38}
39
40void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg)
41{
42 unsigned int rest_of_page;
43
44 walk->sg = sg;
45
46 walk->page = sg->page;
47 walk->len_this_segment = sg->length;
48
49 BUG_ON(!sg->length);
50
51 rest_of_page = PAGE_CACHE_SIZE - (sg->offset & (PAGE_CACHE_SIZE - 1));
52 walk->len_this_page = min(sg->length, rest_of_page);
53 walk->offset = sg->offset;
54}
55
56void scatterwalk_map(struct scatter_walk *walk, int out)
57{
58 walk->data = crypto_kmap(walk->page, out) + walk->offset;
59}
60
61static inline void scatterwalk_unmap(struct scatter_walk *walk, int out)
62{
63 /* walk->data may be pointing the first byte of the next page;
64 however, we know we transfered at least one byte. So,
65 walk->data - 1 will be a virtual address in the mapped page. */
66 crypto_kunmap(walk->data - 1, out);
67}
68
69static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
70 unsigned int more)
71{
72 if (out)
73 flush_dcache_page(walk->page);
74
75 if (more) {
76 walk->len_this_segment -= walk->len_this_page;
77
78 if (walk->len_this_segment) {
79 walk->page++;
80 walk->len_this_page = min(walk->len_this_segment,
81 (unsigned)PAGE_CACHE_SIZE);
82 walk->offset = 0;
83 }
84 else
85 scatterwalk_start(walk, sg_next(walk->sg));
86 }
87}
88
89void scatterwalk_done(struct scatter_walk *walk, int out, int more)
90{
91 scatterwalk_unmap(walk, out);
92 if (walk->len_this_page == 0 || !more)
93 scatterwalk_pagedone(walk, out, more);
94}
95
96/*
97 * Do not call this unless the total length of all of the fragments
98 * has been verified as multiple of the block size.
99 */
100int scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
101 size_t nbytes, int out)
102{
103 do {
104 memcpy_dir(buf, walk->data, walk->len_this_page, out);
105 buf += walk->len_this_page;
106 nbytes -= walk->len_this_page;
107
108 scatterwalk_unmap(walk, out);
109 scatterwalk_pagedone(walk, out, 1);
110 scatterwalk_map(walk, out);
111 } while (nbytes > walk->len_this_page);
112
113 memcpy_dir(buf, walk->data, nbytes, out);
114 return nbytes;
115}