[U-Boot] [PATCH] ARM: armv7: Add early stack for erratum workarounds

[Nishanth Menon]

On 14:47-20181119, Andrew F. Davis wrote:
> Some erratum workarounds call into C code before the stack
> is setup, this can lead to values pushed onto the stack
> being lost, firewall exceptions, and other undefined behavior.
> 
> Setup a temporary stack to allow these functions to work
> correctly.
> 
> Signed-off-by: Andrew F. Davis <afd at ti.com>
> ---
>  arch/arm/cpu/armv7/start.S | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
> index 81edec01bf..0cb6dd39cc 100644
> --- a/arch/arm/cpu/armv7/start.S
> +++ b/arch/arm/cpu/armv7/start.S
> @@ -205,6 +205,15 @@ ENTRY(cpu_init_cp15)
>  	mov	r2, r3, lsl #4		@ shift variant field for combined value
>  	orr	r2, r4, r2		@ r2 has combined CPU variant + revision
>  
> +/* Early stack for ERRATA that needs into call C code */
> +#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
> +	ldr	r0, =(CONFIG_SPL_STACK)
> +#else
> +	ldr	r0, =(CONFIG_SYS_INIT_SP_ADDR)
> +#endif
> +	bic	r0, r0, #7	/* 8-byte alignment for ABI compliance */
> +	mov	sp, r0
> +

Dumb q:
Is this a little too late? bl cpu_init_cp15 gets invoked from reset..
doesnt sp need to be setup prior to the call in?

>  #ifdef CONFIG_ARM_ERRATA_798870
>  	cmp	r2, #0x30		@ Applies to lower than R3p0
>  	bge	skip_errata_798870      @ skip if not affected rev
> -- 
> 2.19.1
> 

-- 
Regards,
Nishanth Menon