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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 | ||
17 | #include <crypto/scatterwalk.h> | |
18 | #include <linux/kernel.h> | |
19 | #include <linux/mm.h> | |
20 | #include <linux/module.h> | |
21 | #include <linux/scatterlist.h> | |
22 | ||
23 | static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out) | |
24 | { | |
25 | void *src = out ? buf : sgdata; | |
26 | void *dst = out ? sgdata : buf; | |
27 | ||
28 | memcpy(dst, src, nbytes); | |
29 | } | |
30 | ||
31 | void scatterwalk_copychunks(void *buf, struct scatter_walk *walk, | |
32 | size_t nbytes, int out) | |
33 | { | |
34 | for (;;) { | |
35 | unsigned int len_this_page = scatterwalk_pagelen(walk); | |
36 | u8 *vaddr; | |
37 | ||
38 | if (len_this_page > nbytes) | |
39 | len_this_page = nbytes; | |
40 | ||
41 | if (out != 2) { | |
42 | vaddr = scatterwalk_map(walk); | |
43 | memcpy_dir(buf, vaddr, len_this_page, out); | |
44 | scatterwalk_unmap(vaddr); | |
45 | } | |
46 | ||
47 | scatterwalk_advance(walk, len_this_page); | |
48 | ||
49 | if (nbytes == len_this_page) | |
50 | break; | |
51 | ||
52 | buf += len_this_page; | |
53 | nbytes -= len_this_page; | |
54 | ||
55 | scatterwalk_pagedone(walk, out & 1, 1); | |
56 | } | |
57 | } | |
58 | EXPORT_SYMBOL_GPL(scatterwalk_copychunks); | |
59 | ||
60 | void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg, | |
61 | unsigned int start, unsigned int nbytes, int out) | |
62 | { | |
63 | struct scatter_walk walk; | |
64 | struct scatterlist tmp[2]; | |
65 | ||
66 | if (!nbytes) | |
67 | return; | |
68 | ||
69 | sg = scatterwalk_ffwd(tmp, sg, start); | |
70 | ||
71 | scatterwalk_start(&walk, sg); | |
72 | scatterwalk_copychunks(buf, &walk, nbytes, out); | |
73 | scatterwalk_done(&walk, out, 0); | |
74 | } | |
75 | EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy); | |
76 | ||
77 | struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2], | |
78 | struct scatterlist *src, | |
79 | unsigned int len) | |
80 | { | |
81 | for (;;) { | |
82 | if (!len) | |
83 | return src; | |
84 | ||
85 | if (src->length > len) | |
86 | break; | |
87 | ||
88 | len -= src->length; | |
89 | src = sg_next(src); | |
90 | } | |
91 | ||
92 | sg_init_table(dst, 2); | |
93 | sg_set_page(dst, sg_page(src), src->length - len, src->offset + len); | |
94 | scatterwalk_crypto_chain(dst, sg_next(src), 0, 2); | |
95 | ||
96 | return dst; | |
97 | } | |
98 | EXPORT_SYMBOL_GPL(scatterwalk_ffwd); |