[U-Boot] [PATCH v2] BUGFIX: arm: data abort in get_bad_stack_swi

[Albert ARIBAUD <albert.u.boot@aribaud.net>]

Hi Tetsuyuki,

On Fri,  5 Apr 2013 10:45:14 +0900, Tetsuyuki Kobayashi
<koba@kmckk.co.jp> wrote:

> When swi instruction is executed, it is expected to get message
> "software interrupt" in console and dump registers and reboot, as
> do_software_interrupt() in arch/arm/lib/interrupts.c.
> But, actually it causes data abort accessing wrong address in get_bad_stack_swi
> macro in arch/arm/cpu/v7/start.S.
> This patch fixes this problem.
> 
> The same mistake in arch/arm/cpu/{arm1136,arm1176,pxa}/start.S.
> 
> Signed-off-by: Tetsuyuki Kobayashi <koba@kmckk.co.jp>
> ---
> Changes for v2:
> - added arch/arm/cpu/{arm1136,arm1176,pxa}/start.S
>   (But not tested, because I don't have test boards of them)
>   arm/arm/cpu/armv7/start.S is tested on KZM-A9-GT board.
> 
>  arch/arm/cpu/arm1136/start.S |    2 +-
>  arch/arm/cpu/arm1176/start.S |    2 +-
>  arch/arm/cpu/armv7/start.S   |    2 +-
>  arch/arm/cpu/pxa/start.S     |    2 +-
>  4 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm/cpu/arm1136/start.S b/arch/arm/cpu/arm1136/start.S
> index eba2324..7b9db2b 100644
> --- a/arch/arm/cpu/arm1136/start.S
> +++ b/arch/arm/cpu/arm1136/start.S
> @@ -392,7 +392,7 @@ cpu_init_crit:
>  	str	r0, [r13]			@ save R0's value.
>  	ldr	r0, IRQ_STACK_START_IN		@ get data regions start
>  	str	lr, [r0]			@ save caller lr in position 0 of saved stack
> -	mrs	r0, spsr			@ get the spsr
> +	mrs	lr, spsr			@ get the spsr
>  	str	lr, [r0, #4]			@ save spsr in position 1 of saved stack
>  	ldr	r0, [r13]			@ restore r0
>  	add	r13, r13, #4			@ pop stack entry

Sorry for not checking this in V1, but I see that get_bad_stack_swi does
not preserve lr, so when bad_save_user_regs is expanded, it will save
the wrong value for lr. You need to restore lr from [r0] before you
restore r0 from [r13].

> diff --git a/arch/arm/cpu/arm1176/start.S b/arch/arm/cpu/arm1176/start.S

> diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S

> diff --git a/arch/arm/cpu/pxa/start.S b/arch/arm/cpu/pxa/start.S

Ditto for all four files, of course.

Amicalement,
-- 
Albert.