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
19static 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
28static 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
35static 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
42static inline void scatterwalk_advance(struct scatter_walk *walk,
43				       unsigned int nbytes)
44{
45	walk->offset += nbytes;
46}
47
48static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
49					       unsigned int alignmask)
50{
51	return !(walk->offset & alignmask);
52}
53
54static inline struct page *scatterwalk_page(struct scatter_walk *walk)
55{
56	return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
57}
58
59static inline void scatterwalk_unmap(void *vaddr)
60{
61	kunmap_atomic(vaddr);
62}
63
64static inline void scatterwalk_start(struct scatter_walk *walk,
65				     struct scatterlist *sg)
66{
67	walk->sg = sg;
68	walk->offset = sg->offset;
69}
70
71static inline void *scatterwalk_map(struct scatter_walk *walk)
72{
73	return kmap_atomic(scatterwalk_page(walk)) +
74	       offset_in_page(walk->offset);
75}
76
77static 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
96static 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
104void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
105			    size_t nbytes, int out);
106void *scatterwalk_map(struct scatter_walk *walk);
107
108void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
109			      unsigned int start, unsigned int nbytes, int out);
110
111struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
112				     struct scatterlist *src,
113				     unsigned int len);
114
115#endif  /* _CRYPTO_SCATTERWALK_H */
116