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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/csky/kernel/atomic.S
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/* SPDX-License-Identifier: GPL-2.0 */

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// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.

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#include <linux/linkage.h>

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#include <abi/entry.h>

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.text

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/*

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 * int csky_cmpxchg(int oldval, int newval, int *ptr)

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 *

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 * If *ptr != oldval && return 1,

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 * else *ptr = newval return 0.

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 */

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ENTRY(csky_cmpxchg)

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	USPTOKSP

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	RD_MEH	a3

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	WR_MEH	a3

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	mfcr	a3, epc

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	addi	a3, TRAP0_SIZE

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	subi    sp, 16

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	stw     a3, (sp, 0)

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	mfcr    a3, epsr

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	stw     a3, (sp, 4)

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	mfcr	a3, usp

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	stw     a3, (sp, 8)

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	psrset	ee

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#ifdef CONFIG_CPU_HAS_LDSTEX

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1:

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	ldex	a3, (a2)

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	cmpne	a0, a3

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	bt16	2f

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	mov	a3, a1

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	stex	a3, (a2)

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	bez	a3, 1b

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2:

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	sync.is

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#else

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GLOBAL(csky_cmpxchg_ldw)

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	ldw	a3, (a2)

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	cmpne	a0, a3

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	bt16	3f

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GLOBAL(csky_cmpxchg_stw)

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	stw	a1, (a2)

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3:

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#endif

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	mvc	a0

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	ldw	a3, (sp, 0)

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	mtcr	a3, epc

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	ldw     a3, (sp, 4)

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	mtcr	a3, epsr

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	ldw     a3, (sp, 8)

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	mtcr	a3, usp

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	addi	sp, 16

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	KSPTOUSP

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	rte

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END(csky_cmpxchg)

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