From mboxrd@z Thu Jan  1 00:00:00 1970
From: Julien Grall <julien.grall@linaro.org>
Subject: Re: [PATCH 16/17] xen: arm: refactor xchg and cmpxchg
 into their own headers
Date: Thu, 20 Mar 2014 17:52:47 +0000
Message-ID: <532B2AEF.5010905@linaro.org>
References: <1395330336.3104.12.camel@kazak.uk.xensource.com>
	<1395330365-9901-16-git-send-email-ian.campbell@citrix.com>
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To: Ian Campbell <ian.campbell@citrix.com>
Cc: stefano.stabellini@eu.citrix.com, tim@xen.org, xen-devel@lists.xen.org
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Hi Ian,

On 03/20/2014 03:46 PM, Ian Campbell wrote:
> diff --git a/xen/include/asm-arm/arm32/cmpxchg.h b/xen/include/asm-arm/arm32/cmpxchg.h
> new file mode 100644
> index 0000000..70c6090
> --- /dev/null
> +++ b/xen/include/asm-arm/arm32/cmpxchg.h
> +static always_inline unsigned long __cmpxchg(
> +    volatile void *ptr, unsigned long old, unsigned long new, int size)
> +{
> +	unsigned long oldval, res;
> +
> +	switch (size) {
> +	case 1:
> +		do {
> +			asm volatile("@ __cmpxchg1\n"
> +			"	ldrexb	%1, [%2]\n"
> +			"	mov	%0, #0\n"
> +			"	teq	%1, %3\n"
> +			"	strexbeq %0, %4, [%2]\n"
> +				: "=&r" (res), "=&r" (oldval)
> +				: "r" (ptr), "Ir" (old), "r" (new)
> +				: "memory", "cc");
> +		} while (res);
> +		break;
> +	case 2:
> +		do {
> +			asm volatile("@ __cmpxchg2\n"
> +			"	ldrexh	%1, [%2]\n"
> +			"	mov	%0, #0\n"
> +			"	teq	%1, %3\n"
> +			"	strexheq %0, %4, [%2]\n"
> +				: "=&r" (res), "=&r" (oldval)
> +				: "r" (ptr), "Ir" (old), "r" (new)
> +				: "memory", "cc");
> +		} while (res);
> +		break;
> +	case 4:
> +		do {
> +			asm volatile("@ __cmpxchg4\n"
> +			"	ldrex	%1, [%2]\n"
> +			"	mov	%0, #0\n"
> +			"	teq	%1, %3\n"
> +			"	strexeq	%0, %4, [%2]\n"
> +				: "=&r" (res), "=&r" (oldval)
> +				: "r" (ptr), "Ir" (old), "r" (new)
> +				: "memory", "cc");
> +	    } while (res);
> +	    break;
> +#if 0
> +	case 8:
> +		do {
> +			asm volatile("@ __cmpxchg8\n"
> +			"	ldrexd	%1, [%2]\n"
> +			"	mov	%0, #0\n"
> +			"	teq	%1, %3\n"
> +			"	strexdeq %0, %4, [%2]\n"
> +				: "=&r" (res), "=&r" (oldval)
> +				: "r" (ptr), "Ir" (old), "r" (new)
> +				: "memory", "cc");
> +		} while (res);
> +		break;
> +#endif

Is it really useful to let the dead code in the header?

Regards,

-- 
Julien Grall