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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/um/sys-i386/atomic64_cx8_32.S
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/*

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 * atomic64_t for 586+

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 *

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 * Copied from arch/x86/lib/atomic64_cx8_32.S

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 *

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 * Copyright © 2010  Luca Barbieri

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 *

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 * This program is free software; you can redistribute it and/or modify

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 * it under the terms of the GNU General Public License as published by

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 * the Free Software Foundation; either version 2 of the License, or

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 * (at your option) any later version.

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 *

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 */

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#include <linux/linkage.h>

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#include <asm/alternative-asm.h>

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#include <asm/dwarf2.h>

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.macro SAVE reg

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	pushl_cfi %\reg

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	CFI_REL_OFFSET \reg, 0

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.endm

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.macro RESTORE reg

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	popl_cfi %\reg

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	CFI_RESTORE \reg

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.endm

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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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ENTRY(atomic64_read_cx8)

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	CFI_STARTPROC

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	read64 %ecx

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	ret

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	CFI_ENDPROC

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ENDPROC(atomic64_read_cx8)

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ENTRY(atomic64_set_cx8)

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	CFI_STARTPROC

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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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	CFI_ENDPROC

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ENDPROC(atomic64_set_cx8)

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ENTRY(atomic64_xchg_cx8)

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	CFI_STARTPROC

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	movl %ebx, %eax

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	movl %ecx, %edx

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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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	CFI_ENDPROC

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ENDPROC(atomic64_xchg_cx8)

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.macro addsub_return func ins insc

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ENTRY(atomic64_\func\()_return_cx8)

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	CFI_STARTPROC

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	SAVE ebp

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	SAVE ebx

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	SAVE esi

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	SAVE 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 %ebp

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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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	RESTORE edi

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	RESTORE esi

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	RESTORE ebx

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	RESTORE ebp

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	ret

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	CFI_ENDPROC

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ENDPROC(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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ENTRY(atomic64_\func\()_return_cx8)

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	CFI_STARTPROC

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	SAVE 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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	\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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	RESTORE ebx

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	ret

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	CFI_ENDPROC

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ENDPROC(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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ENTRY(atomic64_dec_if_positive_cx8)

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	CFI_STARTPROC

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	SAVE 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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	RESTORE ebx

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	ret

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	CFI_ENDPROC

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ENDPROC(atomic64_dec_if_positive_cx8)

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ENTRY(atomic64_add_unless_cx8)

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	CFI_STARTPROC

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	SAVE ebp

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	SAVE ebx

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

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	SAVE edi

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	SAVE esi

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	movl %ecx, %ebp

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	movl %eax, %esi

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	movl %edx, %edi

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	read64 %ebp

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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 %esi, %ebx

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	adcl %edi, %ecx

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	LOCK_PREFIX

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	cmpxchg8b (%ebp)

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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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	CFI_ADJUST_CFA_OFFSET -8

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	RESTORE ebx

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	RESTORE 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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	CFI_ENDPROC

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ENDPROC(atomic64_add_unless_cx8)

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ENTRY(atomic64_inc_not_zero_cx8)

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	CFI_STARTPROC

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	SAVE ebx

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	read64 %esi

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1:

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	testl %eax, %eax

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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 $1, %ebx

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	adcl $0, %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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	RESTORE ebx

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	ret

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4:

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	testl %edx, %edx

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	jne 2b

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	jmp 3b

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	CFI_ENDPROC

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ENDPROC(atomic64_inc_not_zero_cx8)

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