1/*
2 * Cryptographic scatter and gather helpers.
3 *
4 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
5 * Copyright (c) 2002 Adam J. Richter <adam@yggdrasil.com>
6 * Copyright (c) 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
7 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
8 *
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by the Free
11 * Software Foundation; either version 2 of the License, or (at your option)
12 * any later version.
13 *
14 */
15
16#ifndef _CRYPTO_SCATTERWALK_H
17#define _CRYPTO_SCATTERWALK_H
18
19#include <crypto/algapi.h>
20#include <linux/highmem.h>
21#include <linux/kernel.h>
22#include <linux/scatterlist.h>
23
24static inline void scatterwalk_crypto_chain(struct scatterlist *head,
25 struct scatterlist *sg, int num)
26{
27 if (sg)
28 sg_chain(head, num, sg);
29 else
30 sg_mark_end(head);
31}
32
33static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
34{
35 unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
36 unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
37 return len_this_page > len ? len : len_this_page;
38}
39
40static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
41 unsigned int nbytes)
42{
43 unsigned int len_this_page = scatterwalk_pagelen(walk);
44 return nbytes > len_this_page ? len_this_page : nbytes;
45}
46
47static inline void scatterwalk_advance(struct scatter_walk *walk,
48 unsigned int nbytes)
49{
50 walk->offset += nbytes;
51}
52
53static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
54 unsigned int alignmask)
55{
56 return !(walk->offset & alignmask);
57}
58
59static inline struct page *scatterwalk_page(struct scatter_walk *walk)
60{
61 return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
62}
63
64static inline void scatterwalk_unmap(void *vaddr)
65{
66 kunmap_atomic(vaddr);
67}
68
69static inline void scatterwalk_start(struct scatter_walk *walk,
70 struct scatterlist *sg)
71{
72 walk->sg = sg;
73 walk->offset = sg->offset;
74}
75
76static inline void *scatterwalk_map(struct scatter_walk *walk)
77{
78 return kmap_atomic(scatterwalk_page(walk)) +
79 offset_in_page(walk->offset);
80}
81
82static inline void scatterwalk_pagedone(struct scatter_walk *walk, int out,
83 unsigned int more)
84{
85 if (out) {
86 struct page *page;
87
88 page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
89 /* Test ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE first as
90 * PageSlab cannot be optimised away per se due to
91 * use of volatile pointer.
92 */
93 if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE && !PageSlab(page))
94 flush_dcache_page(page);
95 }
96
97 if (more && walk->offset >= walk->sg->offset + walk->sg->length)
98 scatterwalk_start(walk, sg_next(walk->sg));
99}
100
101static inline void scatterwalk_done(struct scatter_walk *walk, int out,
102 int more)
103{
104 if (!more || walk->offset >= walk->sg->offset + walk->sg->length ||
105 !(walk->offset & (PAGE_SIZE - 1)))
106 scatterwalk_pagedone(walk, out, more);
107}
108
109void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
110 size_t nbytes, int out);
111void *scatterwalk_map(struct scatter_walk *walk);
112
113void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
114 unsigned int start, unsigned int nbytes, int out);
115
116struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
117 struct scatterlist *src,
118 unsigned int len);
119
120#endif /* _CRYPTO_SCATTERWALK_H */
121