Merge git://oss.sgi.com:8090/oss/git/rc-fixes
[linux-2.6] / arch / i386 / kernel / semaphore.c
1 /*
2  * i386 semaphore implementation.
3  *
4  * (C) Copyright 1999 Linus Torvalds
5  *
6  * Portions Copyright 1999 Red Hat, Inc.
7  *
8  *      This program is free software; you can redistribute it and/or
9  *      modify it under the terms of the GNU General Public License
10  *      as published by the Free Software Foundation; either version
11  *      2 of the License, or (at your option) any later version.
12  *
13  * rw semaphores implemented November 1999 by Benjamin LaHaise <bcrl@kvack.org>
14  */
15 #include <linux/config.h>
16 #include <asm/semaphore.h>
17
18 /*
19  * The semaphore operations have a special calling sequence that
20  * allow us to do a simpler in-line version of them. These routines
21  * need to convert that sequence back into the C sequence when
22  * there is contention on the semaphore.
23  *
24  * %eax contains the semaphore pointer on entry. Save the C-clobbered
25  * registers (%eax, %edx and %ecx) except %eax whish is either a return
26  * value or just clobbered..
27  */
28 asm(
29 ".section .sched.text\n"
30 ".align 4\n"
31 ".globl __down_failed\n"
32 "__down_failed:\n\t"
33 #if defined(CONFIG_FRAME_POINTER)
34         "pushl %ebp\n\t"
35         "movl  %esp,%ebp\n\t"
36 #endif
37         "pushl %edx\n\t"
38         "pushl %ecx\n\t"
39         "call __down\n\t"
40         "popl %ecx\n\t"
41         "popl %edx\n\t"
42 #if defined(CONFIG_FRAME_POINTER)
43         "movl %ebp,%esp\n\t"
44         "popl %ebp\n\t"
45 #endif
46         "ret"
47 );
48
49 asm(
50 ".section .sched.text\n"
51 ".align 4\n"
52 ".globl __down_failed_interruptible\n"
53 "__down_failed_interruptible:\n\t"
54 #if defined(CONFIG_FRAME_POINTER)
55         "pushl %ebp\n\t"
56         "movl  %esp,%ebp\n\t"
57 #endif
58         "pushl %edx\n\t"
59         "pushl %ecx\n\t"
60         "call __down_interruptible\n\t"
61         "popl %ecx\n\t"
62         "popl %edx\n\t"
63 #if defined(CONFIG_FRAME_POINTER)
64         "movl %ebp,%esp\n\t"
65         "popl %ebp\n\t"
66 #endif
67         "ret"
68 );
69
70 asm(
71 ".section .sched.text\n"
72 ".align 4\n"
73 ".globl __down_failed_trylock\n"
74 "__down_failed_trylock:\n\t"
75 #if defined(CONFIG_FRAME_POINTER)
76         "pushl %ebp\n\t"
77         "movl  %esp,%ebp\n\t"
78 #endif
79         "pushl %edx\n\t"
80         "pushl %ecx\n\t"
81         "call __down_trylock\n\t"
82         "popl %ecx\n\t"
83         "popl %edx\n\t"
84 #if defined(CONFIG_FRAME_POINTER)
85         "movl %ebp,%esp\n\t"
86         "popl %ebp\n\t"
87 #endif
88         "ret"
89 );
90
91 asm(
92 ".section .sched.text\n"
93 ".align 4\n"
94 ".globl __up_wakeup\n"
95 "__up_wakeup:\n\t"
96         "pushl %edx\n\t"
97         "pushl %ecx\n\t"
98         "call __up\n\t"
99         "popl %ecx\n\t"
100         "popl %edx\n\t"
101         "ret"
102 );
103
104 /*
105  * rw spinlock fallbacks
106  */
107 #if defined(CONFIG_SMP)
108 asm(
109 ".section .sched.text\n"
110 ".align 4\n"
111 ".globl __write_lock_failed\n"
112 "__write_lock_failed:\n\t"
113         LOCK "addl      $" RW_LOCK_BIAS_STR ",(%eax)\n"
114 "1:     rep; nop\n\t"
115         "cmpl   $" RW_LOCK_BIAS_STR ",(%eax)\n\t"
116         "jne    1b\n\t"
117         LOCK "subl      $" RW_LOCK_BIAS_STR ",(%eax)\n\t"
118         "jnz    __write_lock_failed\n\t"
119         "ret"
120 );
121
122 asm(
123 ".section .sched.text\n"
124 ".align 4\n"
125 ".globl __read_lock_failed\n"
126 "__read_lock_failed:\n\t"
127         LOCK "incl      (%eax)\n"
128 "1:     rep; nop\n\t"
129         "cmpl   $1,(%eax)\n\t"
130         "js     1b\n\t"
131         LOCK "decl      (%eax)\n\t"
132         "js     __read_lock_failed\n\t"
133         "ret"
134 );
135 #endif