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/pagemap.h>
22 #include <linux/highmem.h>
23 #include <linux/scatterlist.h>
24
memcpy_dir(void * buf,void * sgdata,size_t nbytes,int out)25 static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
26 {
27 void *src = out ? buf : sgdata;
28 void *dst = out ? sgdata : buf;
29
30 memcpy(dst, src, nbytes);
31 }
32
scatterwalk_start(struct scatter_walk * walk,struct scatterlist * sg)33 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg)
34 {
35 walk->sg = sg;
36
37 BUG_ON(!sg->length);
38
39 walk->offset = sg->offset;
40 }
41 EXPORT_SYMBOL_GPL(scatterwalk_start);
42
scatterwalk_map(struct scatter_walk * walk,int out)43 void *scatterwalk_map(struct scatter_walk *walk, int out)
44 {
45 return crypto_kmap(scatterwalk_page(walk), out) +
46 offset_in_page(walk->offset);
47 }
48 EXPORT_SYMBOL_GPL(scatterwalk_map);
49
scatterwalk_pagedone(struct scatter_walk * walk,int out,unsigned int more)50 static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
51 unsigned int more)
52 {
53 if (out) {
54 struct page *page;
55
56 page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
57 if (!PageSlab(page))
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
scatterwalk_done(struct scatter_walk * walk,int out,int more)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
scatterwalk_copychunks(void * buf,struct scatter_walk * walk,size_t nbytes,int out)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
scatterwalk_map_and_copy(void * buf,struct scatterlist * sg,unsigned int start,unsigned int nbytes,int out)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 if (!nbytes)
110 return;
111
112 for (;;) {
113 scatterwalk_start(&walk, sg);
114
115 if (start < offset + sg->length)
116 break;
117
118 offset += sg->length;
119 sg = scatterwalk_sg_next(sg);
120 }
121
122 scatterwalk_advance(&walk, start - offset);
123 scatterwalk_copychunks(buf, &walk, nbytes, out);
124 scatterwalk_done(&walk, out, 0);
125 }
126 EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy);
127