linux-kernel - Re: [v0][PATCH 1/1] powerpc/book3e: disable interrupt after preempt_schedule

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Message-ID: <1359000165.29726.10.camel@pasglop>
Date:	Thu, 24 Jan 2013 15:02:45 +1100
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Tiejun Chen <tiejun.chen@...driver.com>
Cc:	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [v0][PATCH 1/1] powerpc/book3e: disable interrupt after
 preempt_schedule_irq

On Sun, 2013-01-06 at 18:49 +0800, Tiejun Chen wrote:
> In preempt case current arch_local_irq_restore() from
> preempt_schedule_irq() may enable hard interrupt but we really
> should disable interrupts when we return from the interrupt,
> and so that we don't get interrupted after loading SRR0/1.

This is an excellent catch, thanks !

Cheers,
Ben.

> Signed-off-by: Tiejun Chen <tiejun.chen@...driver.com>
> ---
>  arch/powerpc/kernel/entry_64.S |   13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
> index e9a906c..4e1de34 100644
> --- a/arch/powerpc/kernel/entry_64.S
> +++ b/arch/powerpc/kernel/entry_64.S
> @@ -662,6 +662,19 @@ resume_kernel:
>  	ld	r4,TI_FLAGS(r9)
>  	andi.	r0,r4,_TIF_NEED_RESCHED
>  	bne	1b
> +
> +	/*
> +	 * arch_local_irq_restore() from preempt_schedule_irq above may
> +	 * enable hard interrupt but we really should disable interrupts
> +	 * when we return from the interrupt, and so that we don't get
> +	 * interrupted after loading SRR0/1.
> +	 */
> +#ifdef CONFIG_PPC_BOOK3E
> +	wrteei	0
> +#else
> +	ld	r10,PACAKMSR(r13) /* Get kernel MSR without EE */
> +	mtmsrd	r10,1		  /* Update machine state */
> +#endif /* CONFIG_PPC_BOOK3E */
>  #endif /* CONFIG_PREEMPT */
>  
>  	.globl	fast_exc_return_irq


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