1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Cryptographic API.
4 *
5 * Cipher operations.
6 *
7 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
8 * 2002 Adam J. Richter <adam@yggdrasil.com>
9 * 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
10 */
11
12#include <crypto/scatterwalk.h>
13#include <linux/kernel.h>
14#include <linux/mm.h>
15#include <linux/module.h>
16#include <linux/scatterlist.h>
17
18static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
19{
20 void *src = out ? buf : sgdata;
21 void *dst = out ? sgdata : buf;
22
23 memcpy(dst, src, nbytes);
24}
25
26void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
27 size_t nbytes, int out)
28{
29 for (;;) {
30 unsigned int len_this_page = scatterwalk_pagelen(walk);
31 u8 *vaddr;
32
33 if (len_this_page > nbytes)
34 len_this_page = nbytes;
35
36 if (out != 2) {
37 vaddr = scatterwalk_map(walk);
38 memcpy_dir(buf, sgdata: vaddr, nbytes: len_this_page, out);
39 scatterwalk_unmap(vaddr);
40 }
41
42 scatterwalk_advance(walk, nbytes: len_this_page);
43
44 if (nbytes == len_this_page)
45 break;
46
47 buf += len_this_page;
48 nbytes -= len_this_page;
49
50 scatterwalk_pagedone(walk, out: out & 1, more: 1);
51 }
52}
53EXPORT_SYMBOL_GPL(scatterwalk_copychunks);
54
55void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
56 unsigned int start, unsigned int nbytes, int out)
57{
58 struct scatter_walk walk;
59 struct scatterlist tmp[2];
60
61 if (!nbytes)
62 return;
63
64 sg = scatterwalk_ffwd(dst: tmp, src: sg, len: start);
65
66 scatterwalk_start(walk: &walk, sg);
67 scatterwalk_copychunks(buf, &walk, nbytes, out);
68 scatterwalk_done(walk: &walk, out, more: 0);
69}
70EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy);
71
72struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
73 struct scatterlist *src,
74 unsigned int len)
75{
76 for (;;) {
77 if (!len)
78 return src;
79
80 if (src->length > len)
81 break;
82
83 len -= src->length;
84 src = sg_next(src);
85 }
86
87 sg_init_table(dst, 2);
88 sg_set_page(sg: dst, page: sg_page(sg: src), len: src->length - len, offset: src->offset + len);
89 scatterwalk_crypto_chain(head: dst, sg: sg_next(src), num: 2);
90
91 return dst;
92}
93EXPORT_SYMBOL_GPL(scatterwalk_ffwd);
94

source code of linux/crypto/scatterwalk.c