[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>

#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 whish is either a return
 * value or just clobbered..
 */

#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)
	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
	ret
ENDPROC(call_rwsem_down_read_failed)

ENTRY(call_rwsem_down_write_failed)
	save_common_regs
	movq %rax,%rdi
	call rwsem_down_write_failed
	restore_common_regs
	ret
ENDPROC(call_rwsem_down_write_failed)

ENTRY(call_rwsem_wake)
	/* 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:	ret
ENDPROC(call_rwsem_wake)

ENTRY(call_rwsem_downgrade_wake)
	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
	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>
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
a7386694 JB	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
bafaecd1 LT	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
a7386694 JB	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
bafaecd1 LT	90	call rwsem_down_read_failed
131484c8	91	__ASM_SIZE(pop,) %__ASM_REG(dx)
bafaecd1 LT	92	restore_common_regs
bafaecd1 LT	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
bafaecd1 LT	104	ENTRY(call_rwsem_wake)
a7386694 JB	105	/* do nothing if still outstanding active readers */
a7386694 JB	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)
bafaecd1 LT	116	save_common_regs
131484c8	117	__ASM_SIZE(push,) %__ASM_REG(dx)
bafaecd1 LT	118	movq %rax,%rdi
bafaecd1 LT	119	call rwsem_downgrade_wake
131484c8	120	__ASM_SIZE(pop,) %__ASM_REG(dx)
bafaecd1 LT	121	restore_common_regs
bafaecd1 LT	122	ret
39f2205e	123	ENDPROC(call_rwsem_downgrade_wake)