From mboxrd@z Thu Jan  1 00:00:00 1970
From: will.deacon@arm.com (Will Deacon)
Date: Mon, 14 Jan 2013 16:37:55 +0000
Subject: [PATCH 07/16] ARM: bL_platsmp.c: close the kernel entry gate
 before hot-unplugging a CPU
In-Reply-To: <1357777251-13541-8-git-send-email-nicolas.pitre@linaro.org>
References: <1357777251-13541-1-git-send-email-nicolas.pitre@linaro.org>
 <1357777251-13541-8-git-send-email-nicolas.pitre@linaro.org>
Message-ID: <20130114163755.GB31341@mudshark.cambridge.arm.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Thu, Jan 10, 2013 at 12:20:42AM +0000, Nicolas Pitre wrote:
> If for whatever reason a CPU is unexpectedly awaken, it shouldn't
> re-enter the kernel by using whatever entry vector that might have
> been set by a previous operation.
> 
> Signed-off-by: Nicolas Pitre <nico@linaro.org>
> ---
>  arch/arm/common/bL_platsmp.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/arm/common/bL_platsmp.c b/arch/arm/common/bL_platsmp.c
> index 0acb9f4685..0ae44123bf 100644
> --- a/arch/arm/common/bL_platsmp.c
> +++ b/arch/arm/common/bL_platsmp.c
> @@ -63,6 +63,11 @@ static int bL_cpu_disable(unsigned int cpu)
>  
>  static void __ref bL_cpu_die(unsigned int cpu)
>  {
> +	unsigned int mpidr, pcpu, pcluster;
> +	asm ("mrc p15, 0, %0, c0, c0, 5" : "=r" (mpidr));
> +	pcpu = mpidr & 0xff;
> +	pcluster = (mpidr >> 8) & 0xff;

Usual comment about helper functions :)

> +	bL_set_entry_vector(pcpu, pcluster, NULL);

Similar to the power_on story, you need a barrier here (unless you change
your platform_ops API to require barriers).

>  	bL_cpu_power_down();

Will