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gerrit-public.fairphone.software / kernel / msm-4.9 / bb0c2fe0c423d6501395e626501dd8747823cafb / . / arch / x86 / lib / semaphore_32.S
blob: 648fe474178234e24d2c688bd44756ba24e75b4e [file] [log] [blame]
Andi Kleenecaf45e2006-09-26 10:52:29 +0200[diff] [blame]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
Andi Kleenecaf45e2006-09-26 10:52:29 +0200[diff] [blame]16#include <linux/linkage.h>
17#include <asm/rwlock.h>
Adrian Bunk7e02cb92007-10-17 18:04:38 +0200[diff] [blame]18#include <asm/alternative-asm.h>
19#include <asm/frame.h>
Andi Kleenecaf45e2006-09-26 10:52:29 +0200[diff] [blame]20#include <asm/dwarf2.h>
21
22/*
23 * The semaphore operations have a special calling sequence that
24 * allow us to do a simpler in-line version of them. These routines
25 * need to convert that sequence back into the C sequence when
26 * there is contention on the semaphore.
27 *
28 * %eax contains the semaphore pointer on entry. Save the C-clobbered
29 * registers (%eax, %edx and %ecx) except %eax whish is either a return
30 * value or just clobbered..
31 */
Sam Ravnborgc6c2d7a2008-01-30 13:33:37 +0100[diff] [blame]32 .section .sched.text, "ax"
Andi Kleenecaf45e2006-09-26 10:52:29 +0200[diff] [blame]33
34/*
35 * rw spinlock fallbacks
36 */
37#ifdef CONFIG_SMP
38ENTRY(__write_lock_failed)
39 CFI_STARTPROC simple
40 FRAME
412: LOCK_PREFIX
42 addl $ RW_LOCK_BIAS,(%eax)
431: rep; nop
44 cmpl $ RW_LOCK_BIAS,(%eax)
45 jne 1b
46 LOCK_PREFIX
47 subl $ RW_LOCK_BIAS,(%eax)
48 jnz 2b
49 ENDFRAME
50 ret
51 CFI_ENDPROC
John Reiser6b8be6d2008-01-30 13:33:13 +0100[diff] [blame]52 ENDPROC(__write_lock_failed)
Andi Kleenecaf45e2006-09-26 10:52:29 +0200[diff] [blame]53
54ENTRY(__read_lock_failed)
55 CFI_STARTPROC
56 FRAME
572: LOCK_PREFIX
58 incl (%eax)
591: rep; nop
60 cmpl $1,(%eax)
61 js 1b
62 LOCK_PREFIX
63 decl (%eax)
64 js 2b
65 ENDFRAME
66 ret
67 CFI_ENDPROC
John Reiser6b8be6d2008-01-30 13:33:13 +0100[diff] [blame]68 ENDPROC(__read_lock_failed)
Andi Kleenecaf45e2006-09-26 10:52:29 +0200[diff] [blame]69
70#endif
Andi Kleenadd659b2006-09-26 10:52:31 +0200[diff] [blame]71
Ingo Molnar88271e92006-10-05 18:47:22 +0200[diff] [blame]72#ifdef CONFIG_RWSEM_XCHGADD_ALGORITHM
73
Andi Kleenadd659b2006-09-26 10:52:31 +0200[diff] [blame]74/* Fix up special calling conventions */
75ENTRY(call_rwsem_down_read_failed)
76 CFI_STARTPROC
77 push %ecx
78 CFI_ADJUST_CFA_OFFSET 4
79 CFI_REL_OFFSET ecx,0
80 push %edx
81 CFI_ADJUST_CFA_OFFSET 4
82 CFI_REL_OFFSET edx,0
83 call rwsem_down_read_failed
84 pop %edx
85 CFI_ADJUST_CFA_OFFSET -4
86 pop %ecx
87 CFI_ADJUST_CFA_OFFSET -4
88 ret
89 CFI_ENDPROC
John Reiser6b8be6d2008-01-30 13:33:13 +0100[diff] [blame]90 ENDPROC(call_rwsem_down_read_failed)
Andi Kleenadd659b2006-09-26 10:52:31 +0200[diff] [blame]91
92ENTRY(call_rwsem_down_write_failed)
93 CFI_STARTPROC
94 push %ecx
95 CFI_ADJUST_CFA_OFFSET 4
96 CFI_REL_OFFSET ecx,0
97 calll rwsem_down_write_failed
98 pop %ecx
99 CFI_ADJUST_CFA_OFFSET -4
100 ret
101 CFI_ENDPROC
John Reiser6b8be6d2008-01-30 13:33:13 +0100[diff] [blame]102 ENDPROC(call_rwsem_down_write_failed)
Andi Kleenadd659b2006-09-26 10:52:31 +0200[diff] [blame]103
104ENTRY(call_rwsem_wake)
105 CFI_STARTPROC
106 decw %dx /* do nothing if still outstanding active readers */
107 jnz 1f
108 push %ecx
109 CFI_ADJUST_CFA_OFFSET 4
110 CFI_REL_OFFSET ecx,0
111 call rwsem_wake
112 pop %ecx
113 CFI_ADJUST_CFA_OFFSET -4
1141: ret
115 CFI_ENDPROC
John Reiser6b8be6d2008-01-30 13:33:13 +0100[diff] [blame]116 ENDPROC(call_rwsem_wake)
Andi Kleenadd659b2006-09-26 10:52:31 +0200[diff] [blame]117
118/* Fix up special calling conventions */
119ENTRY(call_rwsem_downgrade_wake)
120 CFI_STARTPROC
121 push %ecx
122 CFI_ADJUST_CFA_OFFSET 4
123 CFI_REL_OFFSET ecx,0
124 push %edx
125 CFI_ADJUST_CFA_OFFSET 4
126 CFI_REL_OFFSET edx,0
127 call rwsem_downgrade_wake
128 pop %edx
129 CFI_ADJUST_CFA_OFFSET -4
130 pop %ecx
131 CFI_ADJUST_CFA_OFFSET -4
132 ret
133 CFI_ENDPROC
John Reiser6b8be6d2008-01-30 13:33:13 +0100[diff] [blame]134 ENDPROC(call_rwsem_downgrade_wake)
Andi Kleenadd659b2006-09-26 10:52:31 +0200[diff] [blame]135
Ingo Molnar88271e92006-10-05 18:47:22 +0200[diff] [blame]136#endif