linux-kernel - Re: [PATCH v3 3/5] arm: fiq: Replace default FIQ handler

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Message-ID: <alpine.LFD.2.11.1409081140360.16533@knanqh.ubzr>
Date:	Mon, 8 Sep 2014 11:49:39 -0400 (EDT)
From:	Nicolas Pitre <nicolas.pitre@...aro.org>
To:	Daniel Thompson <daniel.thompson@...aro.org>
cc:	Russell King <linux@....linux.org.uk>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	patches@...aro.org, linaro-kernel@...ts.linaro.org,
	John Stultz <john.stultz@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Sumit Semwal <sumit.semwal@...aro.org>,
	Catalin Marinas <catalin.marinas@....com>
Subject: Re: [PATCH v3 3/5] arm: fiq: Replace default FIQ handler

On Mon, 8 Sep 2014, Daniel Thompson wrote:

> +@
> +@ Taking a FIQ in abort mode is similar to taking a FIQ in SVC mode
> +@ and reuses the same macros. However in abort mode we must also
> +@ save/restore lr_abt and spsr_abt to make nested aborts safe.
> +@
> +	.align 5
> +__fiq_abt:
> +	svc_entry 0, 0
> +
> + ARM(	msr	cpsr_c, #ABT_MODE | PSR_I_BIT | PSR_F_BIT )
> + THUMB( mov	r0, #ABT_MODE | PSR_I_BIT | PSR_F_BIT )
> + THUMB( msr	cpsr_c, r0 )
> +	mov	r1, lr		@ Save lr_abt
> +	mrs	r2, spsr	@ Save spsr_abt, abort is now safe
> + ARM(	msr	cpsr_c, #SVC_MODE | PSR_I_BIT | PSR_F_BIT )
> + THUMB( mov	r0, #SVC_MODE | PSR_I_BIT | PSR_F_BIT )
> + THUMB( msr	cpsr_c, r0 )
> +	push	{r1 - r2}

	stmfd sp!, {r1 - r2}

> +
> +	sub	r0, sp, #8			@ struct pt_regs *regs
> +	bl	handle_fiq_as_nmi
> +
> +	pop	{r1 - r2}

	ldmfd sp!, {r1 - r2}

... so that old binutils we still accept to compile the kernel (in ARM 
mode) are happy.

Otherwise...

Acked-by: Nicolas Pitre <nico@...aro.org>


Nicolas
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