more debug output
[linux-2.4.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/pagemap.h>
19 #include <linux/highmem.h>
20 #include <asm/scatterlist.h>
21 #include "internal.h"
22 #include "scatterwalk.h"
23
24 enum km_type crypto_km_types[] = {
25         KM_USER0,
26         KM_USER1,
27         KM_SOFTIRQ0,
28         KM_SOFTIRQ1,
29 };
30
31 void *scatterwalk_whichbuf(struct scatter_walk *walk, unsigned int nbytes, void *scratch)
32 {
33         if (nbytes <= walk->len_this_page &&
34             (((unsigned long)walk->data) & (PAGE_CACHE_SIZE - 1)) + nbytes <=
35             PAGE_CACHE_SIZE)
36                 return walk->data;
37         else
38                 return scratch;
39 }
40
41 static void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
42 {
43         if (out)
44                 memcpy(sgdata, buf, nbytes);
45         else
46                 memcpy(buf, sgdata, nbytes);
47 }
48
49 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg)
50 {
51         unsigned int rest_of_page;
52
53         walk->sg = sg;
54
55         walk->page = sg->page;
56         walk->len_this_segment = sg->length;
57
58         rest_of_page = PAGE_CACHE_SIZE - (sg->offset & (PAGE_CACHE_SIZE - 1));
59         walk->len_this_page = min(sg->length, rest_of_page);
60         walk->offset = sg->offset;
61 }
62
63 void scatterwalk_map(struct scatter_walk *walk, int out)
64 {
65         walk->data = crypto_kmap(walk->page, out) + walk->offset;
66 }
67
68 static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
69                                  unsigned int more)
70 {
71         /* walk->data may be pointing the first byte of the next page;
72            however, we know we transfered at least one byte.  So,
73            walk->data - 1 will be a virtual address in the mapped page. */
74
75         if (out)
76                 flush_dcache_page(walk->page);
77
78         if (more) {
79                 walk->len_this_segment -= walk->len_this_page;
80
81                 if (walk->len_this_segment) {
82                         walk->page++;
83                         walk->len_this_page = min(walk->len_this_segment,
84                                                   (unsigned)PAGE_CACHE_SIZE);
85                         walk->offset = 0;
86                 }
87                 else
88                         scatterwalk_start(walk, sg_next(walk->sg));
89         }
90 }
91
92 void scatterwalk_done(struct scatter_walk *walk, int out, int more)
93 {
94         crypto_kunmap(walk->data, out);
95         if (walk->len_this_page == 0 || !more)
96                 scatterwalk_pagedone(walk, out, more);
97 }
98
99 /*
100  * Do not call this unless the total length of all of the fragments
101  * has been verified as multiple of the block size.
102  */
103 int scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
104                            size_t nbytes, int out)
105 {
106         if (buf != walk->data) {
107                 while (nbytes > walk->len_this_page) {
108                         memcpy_dir(buf, walk->data, walk->len_this_page, out);
109                         buf += walk->len_this_page;
110                         nbytes -= walk->len_this_page;
111
112                         crypto_kunmap(walk->data, out);
113                         scatterwalk_pagedone(walk, out, 1);
114                         scatterwalk_map(walk, out);
115                 }
116
117                 memcpy_dir(buf, walk->data, nbytes, out);
118         }
119
120         walk->offset += nbytes;
121         walk->len_this_page -= nbytes;
122         walk->len_this_segment -= nbytes;
123         return 0;
124 }