aboutsummaryrefslogtreecommitdiffstats
path: root/crypto/scatterwalk.c
blob: 206c39a97e57d3f3d50d0bf8e72eeb4b929d98c6 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
/*
 * Cryptographic API.
 *
 * Cipher operations.
 *
 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
 *               2002 Adam J. Richter <adam@yggdrasil.com>
 *               2004 Jean-Luc Cooke <jlcooke@certainkey.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 */
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/scatterlist.h>

#include "internal.h"
#include "scatterwalk.h"

static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
{
	void *src = out ? buf : sgdata;
	void *dst = out ? sgdata : buf;

	memcpy(dst, src, nbytes);
}

void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg)
{
	walk->sg = sg;

	BUG_ON(!sg->length);

	walk->offset = sg->offset;
}
EXPORT_SYMBOL_GPL(scatterwalk_start);

void *scatterwalk_map(struct scatter_walk *walk, int out)
{
	return crypto_kmap(scatterwalk_page(walk), out) +
	       offset_in_page(walk->offset);
}
EXPORT_SYMBOL_GPL(scatterwalk_map);

static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
				 unsigned int more)
{
	if (out) {
		struct page *page;

		page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
		flush_dcache_page(page);
	}

	if (more) {
		walk->offset += PAGE_SIZE - 1;
		walk->offset &= PAGE_MASK;
		if (walk->offset >= walk->sg->offset + walk->sg->length)
			scatterwalk_start(walk, sg_next(walk->sg));
	}
}

void scatterwalk_done(struct scatter_walk *walk, int out, int more)
{
	if (!offset_in_page(walk->offset) || !more)
		scatterwalk_pagedone(walk, out, more);
}
EXPORT_SYMBOL_GPL(scatterwalk_done);

void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
			    size_t nbytes, int out)
{
	for (;;) {
		unsigned int len_this_page = scatterwalk_pagelen(walk);
		u8 *vaddr;

		if (len_this_page > nbytes)
			len_this_page = nbytes;

		vaddr = scatterwalk_map(walk, out);
		memcpy_dir(buf, vaddr, len_this_page, out);
		scatterwalk_unmap(vaddr, out);

		scatterwalk_advance(walk, len_this_page);

		if (nbytes == len_this_page)
			break;

		buf += len_this_page;
		nbytes -= len_this_page;

		scatterwalk_pagedone(walk, out, 1);
	}
}
EXPORT_SYMBOL_GPL(scatterwalk_copychunks);

void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
			      unsigned int start, unsigned int nbytes, int out)
{
	struct scatter_walk walk;
	unsigned int offset = 0;

	for (;;) {
		scatterwalk_start(&walk, sg);

		if (start < offset + sg->length)
			break;

		offset += sg->length;
		sg = sg_next(sg);
	}

	scatterwalk_advance(&walk, start - offset);
	scatterwalk_copychunks(buf, &walk, nbytes, out);
	scatterwalk_done(&walk, out, 0);
}
EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy);