[PATCH] arm: proc-v7: pc phy addresses before disable MMU

[Mika Westerberg]

On Sat, Sep 24, 2011 at 10:02:50AM +0200, Per Forlin wrote:
> PC runs virtual addresses when calling cpu_v7_reset(). The MMU
> is switched off and "mov pc, r0" sets pc back to
> virtual addresses even though the MMU is switched off.
> This will result in a crash if the pipeline delay after
> MMU disable is one instruction. To prevent this set PC
> to physical addresses before disabling the MMU.
> 
> Signed-off-by: Per Fransson <per.xx.fransson at stericsson.com>
> Signed-off-by: Per Forlin <per.forlin at stericsson.com>
> ---
>  arch/arm/mm/proc-v7.S |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
> index 9049c07..f26e831 100644
> --- a/arch/arm/mm/proc-v7.S
> +++ b/arch/arm/mm/proc-v7.S
> @@ -64,6 +64,7 @@ ENDPROC(cpu_v7_proc_fin)
>   */
>  	.align	5
>  ENTRY(cpu_v7_reset)
> +	sub	pc, pc, #PAGE_OFFSET+4		@ go to physical addresses

This only works on machines where PHYS_OFFSET is zero.

IIRC, there is a P<->V offset calculated at boot time. Maybe you could use
that instead here?

>  	mrc	p15, 0, r1, c1, c0, 0		@ ctrl register
>  	bic	r1, r1, #0x1			@ ...............m
>   THUMB(	bic	r1, r1, #1 << 30 )		@ SCTLR.TE (Thumb exceptions)
> -- 
> 1.6.3.3
> 
> 
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