linux-kernel - Re: [PATCH v3 10/25] openrisc: add spinlock implementation

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Message-ID: <20170222112933.GN6515@twins.programming.kicks-ass.net>
Date:   Wed, 22 Feb 2017 12:29:33 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Stafford Horne <shorne@...il.com>
Cc:     Jonas Bonn <jonas@...thpole.se>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        linux@...ck-us.net, openrisc@...ts.librecores.org,
        linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH v3 10/25] openrisc: add spinlock implementation

On Wed, Feb 22, 2017 at 04:11:39AM +0900, Stafford Horne wrote:
> +	__asm__ __volatile__(
> +		"1:	l.lwa	%0, 0(%3)	\n"
> +		"	l.srli	%1, %0, 16	\n"
> +		"	l.andi	%2, %0, 0xffff	\n"
> +		"	l.sfeq	%1, %2		\n"
> +		"	l.bnf	1f		\n"
> +		"	 l.ori	%1, r0, 1	\n"
> +		"	l.add	%0, %0, %4	\n"
> +		"	l.swa	0(%3), %0	\n"
> +		"	l.bnf	1b		\n"
> +		"	 l.ori	%1, r0, 0	\n"
> +		"1:				\n"
> +		: "=&r" (slock), "=&r" (contended), "=&r" (tmp)
> +		: "r" (&lock->slock), "r" (1 << TICKET_SHIFT)
> +		: "cc", "memory");

> +	__asm__ __volatile__(
> +		"1:	l.lwa	%0, 0(%1)	\n"
> +		"	l.sfeqi	%0, 0		\n"
> +		"	l.bnf	1f		\n"
> +		"	 l.nop			\n"
> +		"	l.swa	0(%1), %2	\n"
> +		"	l.bnf	1b		\n"
> +		"	 l.nop			\n"
> +		"1:				\n"
> +		: "=&r" (tmp)
> +		: "r" (&rw->lock), "r" (0x80000000)
> +		: "cc", "memory");

> +	__asm__ __volatile__(
> +		"1:	l.lwa	%0, 0(%1)	\n"
> +		"	l.sfeqi	%0, 0		\n"
> +		"	l.bnf	1f		\n"
> +		"	 l.nop			\n"
> +		"	l.swa	 0(%1), %2	\n"
> +		"	l.bnf	1b		\n"
> +		"	 l.nop			\n"
> +		"1:				\n"
> +		: "=&r" (contended)
> +		: "r" (&rw->lock), "r" (0x80000000)
> +		: "cc", "memory");

> +	__asm__ __volatile__(
> +		"1:	l.lwa		%0, 0(%1)	\n"
> +		"	l.sfltsi	%0, -1		\n"
> +		"	l.bf		1f		\n"
> +		"	 l.addi		%0, %0, 1	\n"
> +		"	l.swa		0(%1), %0	\n"
> +		"	l.bnf		1b		\n"
> +		"	 l.nop				\n"
> +		"1:					\n"
> +		: "=&r" (contended)
> +		: "r" (&rw->lock)
> +		: "cc", "memory");

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