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
|
/*
* x86 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/linkage.h>
#include <asm/alternative-asm.h>
#include <asm/frame.h>
#define __ASM_HALF_REG(reg) __ASM_SEL(reg, e##reg)
#define __ASM_HALF_SIZE(inst) __ASM_SEL(inst##w, inst##l)
#ifdef CONFIG_X86_32
/*
* 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 which is either a return
* value or just gets clobbered. Same is true for %edx so make sure GCC
* reloads it after the slow path, by making it hold a temporary, for
* example see ____down_write().
*/
#define save_common_regs \
pushl %ecx
#define restore_common_regs \
popl %ecx
/* Avoid uglifying the argument copying x86-64 needs to do. */
.macro movq src, dst
.endm
#else
/*
* x86-64 rwsem wrappers
*
* This interfaces the inline asm code to the slow-path
* C routines. We need to save the call-clobbered regs
* that the asm does not mark as clobbered, and move the
* argument from %rax to %rdi.
*
* NOTE! We don't need to save %rax, because the functions
* will always return the semaphore pointer in %rax (which
* is also the input argument to these helpers)
*
* The following can clobber %rdx because the asm clobbers it:
* call_rwsem_down_write_failed
* call_rwsem_wake
* but %rdi, %rsi, %rcx, %r8-r11 always need saving.
*/
#define save_common_regs \
pushq %rdi; \
pushq %rsi; \
pushq %rcx; \
pushq %r8; \
pushq %r9; \
pushq %r10; \
pushq %r11
#define restore_common_regs \
popq %r11; \
popq %r10; \
popq %r9; \
popq %r8; \
popq %rcx; \
popq %rsi; \
popq %rdi
#endif
/* Fix up special calling conventions */
ENTRY(call_rwsem_down_read_failed)
FRAME_BEGIN
save_common_regs
__ASM_SIZE(push,) %__ASM_REG(dx)
movq %rax,%rdi
call rwsem_down_read_failed
__ASM_SIZE(pop,) %__ASM_REG(dx)
restore_common_regs
FRAME_END
ret
ENDPROC(call_rwsem_down_read_failed)
ENTRY(call_rwsem_down_read_failed_killable)
FRAME_BEGIN
save_common_regs
__ASM_SIZE(push,) %__ASM_REG(dx)
movq %rax,%rdi
call rwsem_down_read_failed_killable
__ASM_SIZE(pop,) %__ASM_REG(dx)
restore_common_regs
FRAME_END
ret
ENDPROC(call_rwsem_down_read_failed_killable)
ENTRY(call_rwsem_down_write_failed)
FRAME_BEGIN
save_common_regs
movq %rax,%rdi
call rwsem_down_write_failed
restore_common_regs
FRAME_END
ret
ENDPROC(call_rwsem_down_write_failed)
ENTRY(call_rwsem_down_write_failed_killable)
FRAME_BEGIN
save_common_regs
movq %rax,%rdi
call rwsem_down_write_failed_killable
restore_common_regs
FRAME_END
ret
ENDPROC(call_rwsem_down_write_failed_killable)
ENTRY(call_rwsem_wake)
FRAME_BEGIN
/* do nothing if still outstanding active readers */
__ASM_HALF_SIZE(dec) %__ASM_HALF_REG(dx)
jnz 1f
save_common_regs
movq %rax,%rdi
call rwsem_wake
restore_common_regs
1: FRAME_END
ret
ENDPROC(call_rwsem_wake)
ENTRY(call_rwsem_downgrade_wake)
FRAME_BEGIN
save_common_regs
__ASM_SIZE(push,) %__ASM_REG(dx)
movq %rax,%rdi
call rwsem_downgrade_wake
__ASM_SIZE(pop,) %__ASM_REG(dx)
restore_common_regs
FRAME_END
ret
ENDPROC(call_rwsem_downgrade_wake)
|
