[deliverable/linux.git] / arch / x86 / lib / cmpxchg16b_emu.S

/*
 *	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; version 2
 *	of the License.
 *
 */
#include <linux/linkage.h>
#include <asm/percpu.h>

.text

/*
 * Inputs:
 * %rsi : memory location to compare
 * %rax : low 64 bits of old value
 * %rdx : high 64 bits of old value
 * %rbx : low 64 bits of new value
 * %rcx : high 64 bits of new value
 * %al  : Operation successful
 */
ENTRY(this_cpu_cmpxchg16b_emu)

#
# Emulate 'cmpxchg16b %gs:(%rsi)' except we return the result in %al not
# via the ZF.  Caller will access %al to get result.
#
# Note that this is only useful for a cpuops operation.  Meaning that we
# do *not* have a fully atomic operation but just an operation that is
# *atomic* on a single cpu (as provided by the this_cpu_xx class of
# macros).
#
	pushfq
	cli

	cmpq PER_CPU_VAR((%rsi)), %rax
	jne .Lnot_same
	cmpq PER_CPU_VAR(8(%rsi)), %rdx
	jne .Lnot_same

	movq %rbx, PER_CPU_VAR((%rsi))
	movq %rcx, PER_CPU_VAR(8(%rsi))

	popfq
	mov $1, %al
	ret

.Lnot_same:
	popfq
	xor %al,%al
	ret

ENDPROC(this_cpu_cmpxchg16b_emu)
Commit	Line	Data
	1	/*
	2	* This program is free software; you can redistribute it and/or
	3	* modify it under the terms of the GNU General Public License
	4	* as published by the Free Software Foundation; version 2
	5	* of the License.
	6	*
	7	*/
	8	#include <linux/linkage.h>
	9	#include <asm/percpu.h>
	10
	11	.text
	12
	13	/*
	14	* Inputs:
	15	* %rsi : memory location to compare
	16	* %rax : low 64 bits of old value
	17	* %rdx : high 64 bits of old value
	18	* %rbx : low 64 bits of new value
	19	* %rcx : high 64 bits of new value
	20	* %al : Operation successful
	21	*/
	22	ENTRY(this_cpu_cmpxchg16b_emu)
	23
	24	#
	25	# Emulate 'cmpxchg16b %gs:(%rsi)' except we return the result in %al not
	26	# via the ZF. Caller will access %al to get result.
	27	#
	28	# Note that this is only useful for a cpuops operation. Meaning that we
	29	# do not have a fully atomic operation but just an operation that is
	30	# atomic on a single cpu (as provided by the this_cpu_xx class of
	31	# macros).
	32	#
	33	pushfq
	34	cli
	35
	36	cmpq PER_CPU_VAR((%rsi)), %rax
	37	jne .Lnot_same
	38	cmpq PER_CPU_VAR(8(%rsi)), %rdx
	39	jne .Lnot_same
	40
	41	movq %rbx, PER_CPU_VAR((%rsi))
	42	movq %rcx, PER_CPU_VAR(8(%rsi))
	43
	44	popfq
	45	mov $1, %al
	46	ret
	47
	48	.Lnot_same:
	49	popfq
	50	xor %al,%al
	51	ret
	52
	53	ENDPROC(this_cpu_cmpxchg16b_emu)