[SG] Update crypto/ to sg helpers
[linux-2.6.git] / 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 static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
27 {
28         void *src = out ? buf : sgdata;
29         void *dst = out ? sgdata : buf;
30
31         memcpy(dst, src, nbytes);
32 }
33
34 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg)
35 {
36         walk->sg = sg;
37
38         BUG_ON(!sg->length);
39
40         walk->offset = sg->offset;
41 }
42 EXPORT_SYMBOL_GPL(scatterwalk_start);
43
44 void *scatterwalk_map(struct scatter_walk *walk, int out)
45 {
46         return crypto_kmap(scatterwalk_page(walk), out) +
47                offset_in_page(walk->offset);
48 }
49 EXPORT_SYMBOL_GPL(scatterwalk_map);
50
51 static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
52                                  unsigned int more)
53 {
54         if (out) {
55                 struct page *page;
56
57                 page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
58                 flush_dcache_page(page);
59         }
60
61         if (more) {
62                 walk->offset += PAGE_SIZE - 1;
63                 walk->offset &= PAGE_MASK;
64                 if (walk->offset >= walk->sg->offset + walk->sg->length)
65                         scatterwalk_start(walk, scatterwalk_sg_next(walk->sg));
66         }
67 }
68
69 void scatterwalk_done(struct scatter_walk *walk, int out, int more)
70 {
71         if (!offset_in_page(walk->offset) || !more)
72                 scatterwalk_pagedone(walk, out, more);
73 }
74 EXPORT_SYMBOL_GPL(scatterwalk_done);
75
76 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
77                             size_t nbytes, int out)
78 {
79         for (;;) {
80                 unsigned int len_this_page = scatterwalk_pagelen(walk);
81                 u8 *vaddr;
82
83                 if (len_this_page > nbytes)
84                         len_this_page = nbytes;
85
86                 vaddr = scatterwalk_map(walk, out);
87                 memcpy_dir(buf, vaddr, len_this_page, out);
88                 scatterwalk_unmap(vaddr, out);
89
90                 scatterwalk_advance(walk, len_this_page);
91
92                 if (nbytes == len_this_page)
93                         break;
94
95                 buf += len_this_page;
96                 nbytes -= len_this_page;
97
98                 scatterwalk_pagedone(walk, out, 1);
99         }
100 }
101 EXPORT_SYMBOL_GPL(scatterwalk_copychunks);
102
103 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
104                               unsigned int start, unsigned int nbytes, int out)
105 {
106         struct scatter_walk walk;
107         unsigned int offset = 0;
108
109         for (;;) {
110                 scatterwalk_start(&walk, sg);
111
112                 if (start < offset + sg->length)
113                         break;
114
115                 offset += sg->length;
116                 sg = sg_next(sg);
117         }
118
119         scatterwalk_advance(&walk, start - offset);
120         scatterwalk_copychunks(buf, &walk, nbytes, out);
121         scatterwalk_done(&walk, out, 0);
122 }
123 EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy);