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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/x86/lib/atomic64_cx8_32.S
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/* SPDX-License-Identifier: GPL-2.0-or-later */

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/*

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 * atomic64_t for 586+

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 *

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 * Copyright © 2010  Luca Barbieri

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 */

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#include <linux/linkage.h>

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#include <asm/alternative.h>

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.macro read64 reg

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	movl %ebx, %eax

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	movl %ecx, %edx

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/* we need LOCK_PREFIX since otherwise cmpxchg8b always does the write */

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	LOCK_PREFIX

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	cmpxchg8b (\reg)

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.endm

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.macro read64_nonatomic reg

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	movl (\reg), %eax

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	movl 4(\reg), %edx

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.endm

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SYM_FUNC_START(atomic64_read_cx8)

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	read64 %ecx

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	RET

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SYM_FUNC_END(atomic64_read_cx8)

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SYM_FUNC_START(atomic64_set_cx8)

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1:

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/* we don't need LOCK_PREFIX since aligned 64-bit writes

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 * are atomic on 586 and newer */

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	cmpxchg8b (%esi)

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	jne 1b

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	RET

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SYM_FUNC_END(atomic64_set_cx8)

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SYM_FUNC_START(atomic64_xchg_cx8)

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1:

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	LOCK_PREFIX

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	cmpxchg8b (%esi)

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	jne 1b

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	RET

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SYM_FUNC_END(atomic64_xchg_cx8)

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.macro addsub_return func ins insc

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SYM_FUNC_START(atomic64_\func\()_return_cx8)

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	pushl %ebp

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	pushl %ebx

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	pushl %esi

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	pushl %edi

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	movl %eax, %esi

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	movl %edx, %edi

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	movl %ecx, %ebp

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	read64_nonatomic %ecx

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1:

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	movl %eax, %ebx

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	movl %edx, %ecx

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	\ins\()l %esi, %ebx

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	\insc\()l %edi, %ecx

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	LOCK_PREFIX

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	cmpxchg8b (%ebp)

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	jne 1b

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10:

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	movl %ebx, %eax

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	movl %ecx, %edx

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	popl %edi

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	popl %esi

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	popl %ebx

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	popl %ebp

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	RET

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SYM_FUNC_END(atomic64_\func\()_return_cx8)

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.endm

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addsub_return add add adc

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addsub_return sub sub sbb

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.macro incdec_return func ins insc

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SYM_FUNC_START(atomic64_\func\()_return_cx8)

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	pushl %ebx

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	read64_nonatomic %esi

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1:

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	movl %eax, %ebx

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	movl %edx, %ecx

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	\ins\()l $1, %ebx

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	\insc\()l $0, %ecx

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	LOCK_PREFIX

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	cmpxchg8b (%esi)

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	jne 1b

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10:

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	movl %ebx, %eax

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	movl %ecx, %edx

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	popl %ebx

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	RET

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SYM_FUNC_END(atomic64_\func\()_return_cx8)

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.endm

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incdec_return inc add adc

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incdec_return dec sub sbb

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SYM_FUNC_START(atomic64_dec_if_positive_cx8)

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	pushl %ebx

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	read64 %esi

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1:

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	movl %eax, %ebx

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	movl %edx, %ecx

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	subl $1, %ebx

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	sbb $0, %ecx

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	js 2f

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	LOCK_PREFIX

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	cmpxchg8b (%esi)

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	jne 1b

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2:

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	movl %ebx, %eax

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	movl %ecx, %edx

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	popl %ebx

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	RET

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SYM_FUNC_END(atomic64_dec_if_positive_cx8)

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SYM_FUNC_START(atomic64_add_unless_cx8)

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	pushl %ebp

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	pushl %ebx

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/* these just push these two parameters on the stack */

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	pushl %edi

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	pushl %ecx

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	movl %eax, %ebp

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	movl %edx, %edi

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	read64 %esi

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1:

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	cmpl %eax, 0(%esp)

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	je 4f

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2:

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	movl %eax, %ebx

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	movl %edx, %ecx

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	addl %ebp, %ebx

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	adcl %edi, %ecx

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	LOCK_PREFIX

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	cmpxchg8b (%esi)

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	jne 1b

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	movl $1, %eax

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3:

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	addl $8, %esp

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	popl %ebx

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	popl %ebp

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	RET

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4:

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	cmpl %edx, 4(%esp)

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	jne 2b

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	xorl %eax, %eax

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	jmp 3b

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SYM_FUNC_END(atomic64_add_unless_cx8)

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SYM_FUNC_START(atomic64_inc_not_zero_cx8)

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	pushl %ebx

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	read64 %esi

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1:

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	movl %eax, %ecx

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	orl %edx, %ecx

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	jz 3f

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	movl %eax, %ebx

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	xorl %ecx, %ecx

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	addl $1, %ebx

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	adcl %edx, %ecx

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	LOCK_PREFIX

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	cmpxchg8b (%esi)

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	jne 1b

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	movl $1, %eax

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3:

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	popl %ebx

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	RET

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SYM_FUNC_END(atomic64_inc_not_zero_cx8)

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