1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3 * Cryptographic scatter and gather helpers.
4 *
5 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
6 * Copyright (c) 2002 Adam J. Richter <adam@yggdrasil.com>
7 * Copyright (c) 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
8 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
9 */
10
11 #ifndef _CRYPTO_SCATTERWALK_H
12 #define _CRYPTO_SCATTERWALK_H
13
14 #include <crypto/algapi.h>
15
16 #include <linux/highmem.h>
17 #include <linux/mm.h>
18 #include <linux/scatterlist.h>
19
20 static inline void scatterwalk_crypto_chain(struct scatterlist *head,
21 struct scatterlist *sg, int num)
22 {
23 if (sg)
24 sg_chain(head, num, sg);
25 else
26 sg_mark_end(head);
27 }
28
29 static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
30 {
31 unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
32 unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
33 return len_this_page > len ? len : len_this_page;
34 }
35
36 static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
37 unsigned int nbytes)
38 {
39 unsigned int len_this_page = scatterwalk_pagelen(walk);
40 return nbytes > len_this_page ? len_this_page : nbytes;
41 }
42
43 static inline void scatterwalk_advance(struct scatter_walk *walk,
44 unsigned int nbytes)
45 {
46 walk->offset += nbytes;
47 }
48
49 static inline struct page *scatterwalk_page(struct scatter_walk *walk)
50 {
51 return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
52 }
53
54 static inline void scatterwalk_unmap(void *vaddr)
55 {
56 kunmap_local(vaddr);
57 }
58
59 static inline void scatterwalk_start(struct scatter_walk *walk,
60 struct scatterlist *sg)
61 {
62 walk->sg = sg;
63 walk->offset = sg->offset;
64 }
65
66 static inline void *scatterwalk_map(struct scatter_walk *walk)
67 {
68 return kmap_local_page(scatterwalk_page(walk)) +
69 offset_in_page(walk->offset);
70 }
71
72 static inline void scatterwalk_pagedone(struct scatter_walk *walk, int out,
73 unsigned int more)
74 {
75 if (out) {
76 struct page *page;
77
78 page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
79 flush_dcache_page(page);
80 }
81
82 if (more && walk->offset >= walk->sg->offset + walk->sg->length)
83 scatterwalk_start(walk, sg_next(walk->sg));
84 }
85
86 static inline void scatterwalk_done(struct scatter_walk *walk, int out,
87 int more)
88 {
89 if (!more || walk->offset >= walk->sg->offset + walk->sg->length ||
90 !(walk->offset & (PAGE_SIZE - 1)))
91 scatterwalk_pagedone(walk, out, more);
92 }
93
94 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
95 size_t nbytes, int out);
96
97 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
98 unsigned int start, unsigned int nbytes, int out);
99
100 struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
101 struct scatterlist *src,
102 unsigned int len);
103
104 #endif /* _CRYPTO_SCATTERWALK_H */
105
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