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

[Tetsuyuki Kobayashi]

Hi Albert

(04/05/2013 04:04 PM), Albert ARIBAUD wrote:
> Hi Tetsuyuki,
> 
> On Fri,  5 Apr 2013 10:45:14 +0900, Tetsuyuki Kobayashi
> <koba at 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 at 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].

Thank you, I was not aware that.
The dumped lr value was wrong.
I am going to post V3 patch for all 4 files.

> 
>> 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,
>