[deliverable/linux.git] / arch / x86 / lib / rwsem.S

/*
 * 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_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)
Commit	Line	Data
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>
3387a535	18	#include <asm/frame.h>
a7386694 JB	19
	20	#define __ASM_HALF_REG(reg) __ASM_SEL(reg, e##reg)
	21	#define __ASM_HALF_SIZE(inst) __ASM_SEL(inst##w, inst##l)
	22
	23	#ifdef CONFIG_X86_32
	24
	25	/*
	26	* The semaphore operations have a special calling sequence that
	27	* allow us to do a simpler in-line version of them. These routines
	28	* need to convert that sequence back into the C sequence when
	29	* there is contention on the semaphore.
	30	*
	31	* %eax contains the semaphore pointer on entry. Save the C-clobbered
4544ba8c BP	32	* registers (%eax, %edx and %ecx) except %eax which is either a return
	33	* value or just gets clobbered. Same is true for %edx so make sure GCC
	34	* reloads it after the slow path, by making it hold a temporary, for
	35	* example see ____down_write().
a7386694 JB	36	*/
	37
	38	#define save_common_regs \
131484c8	39	pushl %ecx
a7386694 JB	40
a7386694 JB	41	#define restore_common_regs \
131484c8	42	popl %ecx
a7386694 JB	43
	44	/* Avoid uglifying the argument copying x86-64 needs to do. */
	45	.macro movq src, dst
	46	.endm
	47
	48	#else
	49
bafaecd1 LT	50	/*
	51	* x86-64 rwsem wrappers
	52	*
	53	* This interfaces the inline asm code to the slow-path
	54	* C routines. We need to save the call-clobbered regs
	55	* that the asm does not mark as clobbered, and move the
	56	* argument from %rax to %rdi.
	57	*
	58	* NOTE! We don't need to save %rax, because the functions
	59	* will always return the semaphore pointer in %rax (which
	60	* is also the input argument to these helpers)
	61	*
	62	* The following can clobber %rdx because the asm clobbers it:
	63	* call_rwsem_down_write_failed
	64	* call_rwsem_wake
	65	* but %rdi, %rsi, %rcx, %r8-r11 always need saving.
	66	*/
	67
bafaecd1	68	#define save_common_regs \
131484c8 IM	69	pushq %rdi; \
	70	pushq %rsi; \
	71	pushq %rcx; \
	72	pushq %r8; \
	73	pushq %r9; \
	74	pushq %r10; \
	75	pushq %r11
bafaecd1 LT	76
bafaecd1 LT	77	#define restore_common_regs \
131484c8 IM	78	popq %r11; \
	79	popq %r10; \
	80	popq %r9; \
	81	popq %r8; \
	82	popq %rcx; \
	83	popq %rsi; \
	84	popq %rdi
bafaecd1	85
a7386694 JB	86	#endif
a7386694 JB	87
bafaecd1 LT	88	/* Fix up special calling conventions */
bafaecd1 LT	89	ENTRY(call_rwsem_down_read_failed)
3387a535	90	FRAME_BEGIN
bafaecd1	91	save_common_regs
131484c8	92	__ASM_SIZE(push,) %__ASM_REG(dx)
bafaecd1 LT	93	movq %rax,%rdi
bafaecd1 LT	94	call rwsem_down_read_failed
131484c8	95	__ASM_SIZE(pop,) %__ASM_REG(dx)
bafaecd1	96	restore_common_regs
3387a535	97	FRAME_END
bafaecd1	98	ret
39f2205e	99	ENDPROC(call_rwsem_down_read_failed)
bafaecd1 LT	100
bafaecd1 LT	101	ENTRY(call_rwsem_down_write_failed)
3387a535	102	FRAME_BEGIN
bafaecd1 LT	103	save_common_regs
	104	movq %rax,%rdi
	105	call rwsem_down_write_failed
	106	restore_common_regs
3387a535	107	FRAME_END
bafaecd1	108	ret
39f2205e	109	ENDPROC(call_rwsem_down_write_failed)
bafaecd1	110
664b4e24	111	ENTRY(call_rwsem_down_write_failed_killable)
00fb16e2	112	FRAME_BEGIN
664b4e24 MH	113	save_common_regs
	114	movq %rax,%rdi
	115	call rwsem_down_write_failed_killable
	116	restore_common_regs
00fb16e2	117	FRAME_END
664b4e24 MH	118	ret
	119	ENDPROC(call_rwsem_down_write_failed_killable)
	120
bafaecd1	121	ENTRY(call_rwsem_wake)
3387a535	122	FRAME_BEGIN
a7386694 JB	123	/* do nothing if still outstanding active readers */
a7386694 JB	124	__ASM_HALF_SIZE(dec) %__ASM_HALF_REG(dx)
bafaecd1 LT	125	jnz 1f
	126	save_common_regs
	127	movq %rax,%rdi
	128	call rwsem_wake
	129	restore_common_regs
3387a535 JP	130	1: FRAME_END
3387a535 JP	131	ret
39f2205e	132	ENDPROC(call_rwsem_wake)
bafaecd1	133
bafaecd1	134	ENTRY(call_rwsem_downgrade_wake)
3387a535	135	FRAME_BEGIN
bafaecd1	136	save_common_regs
131484c8	137	__ASM_SIZE(push,) %__ASM_REG(dx)
bafaecd1 LT	138	movq %rax,%rdi
bafaecd1 LT	139	call rwsem_downgrade_wake
131484c8	140	__ASM_SIZE(pop,) %__ASM_REG(dx)
bafaecd1	141	restore_common_regs
3387a535	142	FRAME_END
bafaecd1	143	ret
39f2205e	144	ENDPROC(call_rwsem_downgrade_wake)