aboutsummaryrefslogtreecommitdiffstats
path: root/crypto/xor.c
blob: 65c7b416b4a3e4d9e2ad08c41a1fcec06e222f8e (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
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
/*
 * xor.c : Multiple Devices driver for Linux
 *
 * Copyright (C) 1996, 1997, 1998, 1999, 2000,
 * Ingo Molnar, Matti Aarnio, Jakub Jelinek, Richard Henderson.
 *
 * Dispatch optimized RAID-5 checksumming functions.
 *
 * 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, or (at your option)
 * any later version.
 *
 * You should have received a copy of the GNU General Public License
 * (for example /usr/src/linux/COPYING); if not, write to the Free
 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#define BH_TRACE 0
#include <linux/module.h>
#include <linux/gfp.h>
#include <linux/raid/xor.h>
#include <linux/jiffies.h>
#include <linux/preempt.h>
#include <asm/xor.h>

/* The xor routines to use.  */
static struct xor_block_template *active_template;

void
xor_blocks(unsigned int src_count, unsigned int bytes, void *dest, void **srcs)
{
	unsigned long *p1, *p2, *p3, *p4;

	p1 = (unsigned long *) srcs[0];
	if (src_count == 1) {
		active_template->do_2(bytes, dest, p1);
		return;
	}

	p2 = (unsigned long *) srcs[1];
	if (src_count == 2) {
		active_template->do_3(bytes, dest, p1, p2);
		return;
	}

	p3 = (unsigned long *) srcs[2];
	if (src_count == 3) {
		active_template->do_4(bytes, dest, p1, p2, p3);
		return;
	}

	p4 = (unsigned long *) srcs[3];
	active_template->do_5(bytes, dest, p1, p2, p3, p4);
}
EXPORT_SYMBOL(xor_blocks);

/* Set of all registered templates.  */
static struct xor_block_template *template_list;

#define BENCH_SIZE (PAGE_SIZE)

static void
do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
{
	int speed;
	unsigned long now, j;
	int i, count, max;

	tmpl->next = template_list;
	template_list = tmpl;

	preempt_disable();

	/*
	 * Count the number of XORs done during a whole jiffy, and use
	 * this to calculate the speed of checksumming.  We use a 2-page
	 * allocation to have guaranteed color L1-cache layout.
	 */
	max = 0;
	for (i = 0; i < 5; i++) {
		j = jiffies;
		count = 0;
		while ((now = jiffies) == j)
			cpu_relax();
		while (time_before(jiffies, now + 1)) {
			mb(); /* prevent loop optimzation */
			tmpl->do_2(BENCH_SIZE, b1, b2);
			mb();
			count++;
			mb();
		}
		if (count > max)
			max = count;
	}

	preempt_enable();

	speed = max * (HZ * BENCH_SIZE / 1024);
	tmpl->speed = speed;

	printk(KERN_INFO "   %-10s: %5d.%03d MB/sec\n", tmpl->name,
	       speed / 1000, speed % 1000);
}

static int __init
calibrate_xor_blocks(void)
{
	void *b1, *b2;
	struct xor_block_template *f, *fastest;

	/*
	 * Note: Since the memory is not actually used for _anything_ but to
	 * test the XOR speed, we don't really want kmemcheck to warn about
	 * reading uninitialized bytes here.
	 */
	b1 = (void *) __get_free_pages(GFP_KERNEL | __GFP_NOTRACK, 2);
	if (!b1) {
		printk(KERN_WARNING "xor: Yikes!  No memory available.\n");
		return -ENOMEM;
	}
	b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE;

	/*
	 * If this arch/cpu has a short-circuited selection, don't loop through
	 * all the possible functions, just test the best one
	 */

	fastest = NULL;

#ifdef XOR_SELECT_TEMPLATE
		fastest = XOR_SELECT_TEMPLATE(fastest);
#endif

#define xor_speed(templ)	do_xor_speed((templ), b1, b2)

	if (fastest) {
		printk(KERN_INFO "xor: automatically using best "
				 "checksumming function:\n");
		xor_speed(fastest);
		goto out;
	} else {
		printk(KERN_INFO "xor: measuring software checksum speed\n");
		XOR_TRY_TEMPLATES;
		fastest = template_list;
		for (f = fastest; f; f = f->next)
			if (f->speed > fastest->speed)
				fastest = f;
	}

	printk(KERN_INFO "xor: using function: %s (%d.%03d MB/sec)\n",
	       fastest->name, fastest->speed / 1000, fastest->speed % 1000);

#undef xor_speed

 out:
	free_pages((unsigned long)b1, 2);

	active_template = fastest;
	return 0;
}

static __exit void xor_exit(void) { }

MODULE_LICENSE("GPL");

/* when built-in xor.o must initialize before drivers/md/md.o */
core_initcall(calibrate_xor_blocks);
module_exit(xor_exit);