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 #include <linux/highmem.h>
16 #include <linux/kernel.h>
17 #include <linux/scatterlist.h>
18
scatterwalk_crypto_chain(struct scatterlist * head,struct scatterlist * sg,int num)19 static inline void scatterwalk_crypto_chain(struct scatterlist *head,
20 struct scatterlist *sg, int num)
21 {
22 if (sg)
23 sg_chain(head, num, sg);
24 else
25 sg_mark_end(head);
26 }
27
scatterwalk_pagelen(struct scatter_walk * walk)28 static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
29 {
30 unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
31 unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
32 return len_this_page > len ? len : len_this_page;
33 }
34
scatterwalk_clamp(struct scatter_walk * walk,unsigned int nbytes)35 static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
36 unsigned int nbytes)
37 {
38 unsigned int len_this_page = scatterwalk_pagelen(walk);
39 return nbytes > len_this_page ? len_this_page : nbytes;
40 }
41
scatterwalk_advance(struct scatter_walk * walk,unsigned int nbytes)42 static inline void scatterwalk_advance(struct scatter_walk *walk,
43 unsigned int nbytes)
44 {
45 walk->offset += nbytes;
46 }
47
scatterwalk_aligned(struct scatter_walk * walk,unsigned int alignmask)48 static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
49 unsigned int alignmask)
50 {
51 return !(walk->offset & alignmask);
52 }
53
scatterwalk_page(struct scatter_walk * walk)54 static inline struct page *scatterwalk_page(struct scatter_walk *walk)
55 {
56 return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
57 }
58
scatterwalk_unmap(void * vaddr)59 static inline void scatterwalk_unmap(void *vaddr)
60 {
61 kunmap_atomic(vaddr);
62 }
63
scatterwalk_start(struct scatter_walk * walk,struct scatterlist * sg)64 static inline void scatterwalk_start(struct scatter_walk *walk,
65 struct scatterlist *sg)
66 {
67 walk->sg = sg;
68 walk->offset = sg->offset;
69 }
70
scatterwalk_map(struct scatter_walk * walk)71 static inline void *scatterwalk_map(struct scatter_walk *walk)
72 {
73 return kmap_atomic(scatterwalk_page(walk)) +
74 offset_in_page(walk->offset);
75 }
76
scatterwalk_pagedone(struct scatter_walk * walk,int out,unsigned int more)77 static inline void scatterwalk_pagedone(struct scatter_walk *walk, int out,
78 unsigned int more)
79 {
80 if (out) {
81 struct page *page;
82
83 page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
84 /* Test ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE first as
85 * PageSlab cannot be optimised away per se due to
86 * use of volatile pointer.
87 */
88 if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE && !PageSlab(page))
89 flush_dcache_page(page);
90 }
91
92 if (more && walk->offset >= walk->sg->offset + walk->sg->length)
93 scatterwalk_start(walk, sg_next(walk->sg));
94 }
95
scatterwalk_done(struct scatter_walk * walk,int out,int more)96 static inline void scatterwalk_done(struct scatter_walk *walk, int out,
97 int more)
98 {
99 if (!more || walk->offset >= walk->sg->offset + walk->sg->length ||
100 !(walk->offset & (PAGE_SIZE - 1)))
101 scatterwalk_pagedone(walk, out, more);
102 }
103
104 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
105 size_t nbytes, int out);
106 void *scatterwalk_map(struct scatter_walk *walk);
107
108 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
109 unsigned int start, unsigned int nbytes, int out);
110
111 struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
112 struct scatterlist *src,
113 unsigned int len);
114
115 #endif /* _CRYPTO_SCATTERWALK_H */
116