summaryrefslogtreecommitdiff
path: root/arch/i386/kernel/semaphore.c
blob: 967dc74df9eeb69750077eaf783bc5af587788a4 (plain)
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
/*
 * i386 semaphore implementation.
 *
 * (C) Copyright 1999 Linus Torvalds
 *
 * Portions Copyright 1999 Red Hat, Inc.
 *
 *	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.
 *
 * rw semaphores implemented November 1999 by Benjamin LaHaise <bcrl@kvack.org>
 */
#include <linux/config.h>
#include <asm/semaphore.h>

/*
 * The semaphore operations have a special calling sequence that
 * allow us to do a simpler in-line version of them. These routines
 * need to convert that sequence back into the C sequence when
 * there is contention on the semaphore.
 *
 * %eax contains the semaphore pointer on entry. Save the C-clobbered
 * registers (%eax, %edx and %ecx) except %eax whish is either a return
 * value or just clobbered..
 */
asm(
".section .sched.text\n"
".align 4\n"
".globl __down_failed\n"
"__down_failed:\n\t"
#if defined(CONFIG_FRAME_POINTER)
	"pushl %ebp\n\t"
	"movl  %esp,%ebp\n\t"
#endif
	"pushl %edx\n\t"
	"pushl %ecx\n\t"
	"call __down\n\t"
	"popl %ecx\n\t"
	"popl %edx\n\t"
#if defined(CONFIG_FRAME_POINTER)
	"movl %ebp,%esp\n\t"
	"popl %ebp\n\t"
#endif
	"ret"
);

asm(
".section .sched.text\n"
".align 4\n"
".globl __down_failed_interruptible\n"
"__down_failed_interruptible:\n\t"
#if defined(CONFIG_FRAME_POINTER)
	"pushl %ebp\n\t"
	"movl  %esp,%ebp\n\t"
#endif
	"pushl %edx\n\t"
	"pushl %ecx\n\t"
	"call __down_interruptible\n\t"
	"popl %ecx\n\t"
	"popl %edx\n\t"
#if defined(CONFIG_FRAME_POINTER)
	"movl %ebp,%esp\n\t"
	"popl %ebp\n\t"
#endif
	"ret"
);

asm(
".section .sched.text\n"
".align 4\n"
".globl __down_failed_trylock\n"
"__down_failed_trylock:\n\t"
#if defined(CONFIG_FRAME_POINTER)
	"pushl %ebp\n\t"
	"movl  %esp,%ebp\n\t"
#endif
	"pushl %edx\n\t"
	"pushl %ecx\n\t"
	"call __down_trylock\n\t"
	"popl %ecx\n\t"
	"popl %edx\n\t"
#if defined(CONFIG_FRAME_POINTER)
	"movl %ebp,%esp\n\t"
	"popl %ebp\n\t"
#endif
	"ret"
);

asm(
".section .sched.text\n"
".align 4\n"
".globl __up_wakeup\n"
"__up_wakeup:\n\t"
	"pushl %edx\n\t"
	"pushl %ecx\n\t"
	"call __up\n\t"
	"popl %ecx\n\t"
	"popl %edx\n\t"
	"ret"
);

/*
 * rw spinlock fallbacks
 */
#if defined(CONFIG_SMP)
asm(
".section .sched.text\n"
".align	4\n"
".globl	__write_lock_failed\n"
"__write_lock_failed:\n\t"
	LOCK_PREFIX "addl	$" RW_LOCK_BIAS_STR ",(%eax)\n"
"1:	rep; nop\n\t"
	"cmpl	$" RW_LOCK_BIAS_STR ",(%eax)\n\t"
	"jne	1b\n\t"
	LOCK_PREFIX "subl	$" RW_LOCK_BIAS_STR ",(%eax)\n\t"
	"jnz	__write_lock_failed\n\t"
	"ret"
);

asm(
".section .sched.text\n"
".align	4\n"
".globl	__read_lock_failed\n"
"__read_lock_failed:\n\t"
	LOCK_PREFIX "incl	(%eax)\n"
"1:	rep; nop\n\t"
	"cmpl	$1,(%eax)\n\t"
	"js	1b\n\t"
	LOCK_PREFIX "decl	(%eax)\n\t"
	"js	__read_lock_failed\n\t"
	"ret"
);
#endif