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a7386694 JB |
1 | /* |
2 | * x86 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 | ||
16 | #include <linux/linkage.h> | |
17 | #include <asm/alternative-asm.h> | |
a7386694 JB |
18 | |
19 | #define __ASM_HALF_REG(reg) __ASM_SEL(reg, e##reg) | |
20 | #define __ASM_HALF_SIZE(inst) __ASM_SEL(inst##w, inst##l) | |
21 | ||
22 | #ifdef CONFIG_X86_32 | |
23 | ||
24 | /* | |
25 | * The semaphore operations have a special calling sequence that | |
26 | * allow us to do a simpler in-line version of them. These routines | |
27 | * need to convert that sequence back into the C sequence when | |
28 | * there is contention on the semaphore. | |
29 | * | |
30 | * %eax contains the semaphore pointer on entry. Save the C-clobbered | |
31 | * registers (%eax, %edx and %ecx) except %eax whish is either a return | |
32 | * value or just clobbered.. | |
33 | */ | |
34 | ||
35 | #define save_common_regs \ | |
131484c8 | 36 | pushl %ecx |
a7386694 JB |
37 | |
38 | #define restore_common_regs \ | |
131484c8 | 39 | popl %ecx |
a7386694 JB |
40 | |
41 | /* Avoid uglifying the argument copying x86-64 needs to do. */ | |
42 | .macro movq src, dst | |
43 | .endm | |
44 | ||
45 | #else | |
46 | ||
bafaecd1 LT |
47 | /* |
48 | * x86-64 rwsem wrappers | |
49 | * | |
50 | * This interfaces the inline asm code to the slow-path | |
51 | * C routines. We need to save the call-clobbered regs | |
52 | * that the asm does not mark as clobbered, and move the | |
53 | * argument from %rax to %rdi. | |
54 | * | |
55 | * NOTE! We don't need to save %rax, because the functions | |
56 | * will always return the semaphore pointer in %rax (which | |
57 | * is also the input argument to these helpers) | |
58 | * | |
59 | * The following can clobber %rdx because the asm clobbers it: | |
60 | * call_rwsem_down_write_failed | |
61 | * call_rwsem_wake | |
62 | * but %rdi, %rsi, %rcx, %r8-r11 always need saving. | |
63 | */ | |
64 | ||
bafaecd1 | 65 | #define save_common_regs \ |
131484c8 IM |
66 | pushq %rdi; \ |
67 | pushq %rsi; \ | |
68 | pushq %rcx; \ | |
69 | pushq %r8; \ | |
70 | pushq %r9; \ | |
71 | pushq %r10; \ | |
72 | pushq %r11 | |
bafaecd1 LT |
73 | |
74 | #define restore_common_regs \ | |
131484c8 IM |
75 | popq %r11; \ |
76 | popq %r10; \ | |
77 | popq %r9; \ | |
78 | popq %r8; \ | |
79 | popq %rcx; \ | |
80 | popq %rsi; \ | |
81 | popq %rdi | |
bafaecd1 | 82 | |
a7386694 JB |
83 | #endif |
84 | ||
bafaecd1 LT |
85 | /* Fix up special calling conventions */ |
86 | ENTRY(call_rwsem_down_read_failed) | |
87 | save_common_regs | |
131484c8 | 88 | __ASM_SIZE(push,) %__ASM_REG(dx) |
bafaecd1 LT |
89 | movq %rax,%rdi |
90 | call rwsem_down_read_failed | |
131484c8 | 91 | __ASM_SIZE(pop,) %__ASM_REG(dx) |
bafaecd1 LT |
92 | restore_common_regs |
93 | ret | |
39f2205e | 94 | ENDPROC(call_rwsem_down_read_failed) |
bafaecd1 LT |
95 | |
96 | ENTRY(call_rwsem_down_write_failed) | |
97 | save_common_regs | |
98 | movq %rax,%rdi | |
99 | call rwsem_down_write_failed | |
100 | restore_common_regs | |
101 | ret | |
39f2205e | 102 | ENDPROC(call_rwsem_down_write_failed) |
bafaecd1 LT |
103 | |
104 | ENTRY(call_rwsem_wake) | |
a7386694 JB |
105 | /* do nothing if still outstanding active readers */ |
106 | __ASM_HALF_SIZE(dec) %__ASM_HALF_REG(dx) | |
bafaecd1 LT |
107 | jnz 1f |
108 | save_common_regs | |
109 | movq %rax,%rdi | |
110 | call rwsem_wake | |
111 | restore_common_regs | |
112 | 1: ret | |
39f2205e | 113 | ENDPROC(call_rwsem_wake) |
bafaecd1 | 114 | |
bafaecd1 LT |
115 | ENTRY(call_rwsem_downgrade_wake) |
116 | save_common_regs | |
131484c8 | 117 | __ASM_SIZE(push,) %__ASM_REG(dx) |
bafaecd1 LT |
118 | movq %rax,%rdi |
119 | call rwsem_downgrade_wake | |
131484c8 | 120 | __ASM_SIZE(pop,) %__ASM_REG(dx) |
bafaecd1 LT |
121 | restore_common_regs |
122 | ret | |
39f2205e | 123 | ENDPROC(call_rwsem_downgrade_wake) |