[U-Boot] [PATCHv2 1/2] mpc85xx: Initial SP alignment is wrong.

[Joakim Tjernlund]

Ping?

>
> PowerPC mandates SP to be 16 bytes aligned.
> Furthermore, a stack frame is added, pointing to the reset vector
> which may in the way when gdb is walking the stack because
> the reset vector may not accessible depending on emulator settings.
> Also use a temp register so gdb doesn't pick up intermediate values.
>
> Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund at transmode.se>
> ---
>
>  v2 - Address Scott Wood's comments
>  arch/powerpc/cpu/mpc85xx/start.S |   16 +++++-----------
>  1 files changed, 5 insertions(+), 11 deletions(-)
>
> diff --git arch/powerpc/cpu/mpc85xx/start.S arch/powerpc/cpu/mpc85xx/start.S
> index 8d66cf1..4973682 100644
> --- arch/powerpc/cpu/mpc85xx/start.S
> +++ arch/powerpc/cpu/mpc85xx/start.S
> @@ -848,18 +848,12 @@ version_string:
>     .globl   _start_cont
>  _start_cont:
>     /* Setup the stack in initial RAM,could be L2-as-SRAM or L1 dcache*/
> -   lis   r1,CONFIG_SYS_INIT_RAM_ADDR at h
> -   ori   r1,r1,CONFIG_SYS_INIT_SP_OFFSET at l
> -
> +   lis   r3,(CONFIG_SYS_INIT_RAM_ADDR)@h
> +   ori   r3,r3,((CONFIG_SYS_INIT_SP_OFFSET-16)&~0xf)@l /* Align to 16 */
>     li   r0,0
> -   stwu   r0,-4(r1)
> -   stwu   r0,-4(r1)      /* Terminate call chain */
> -
> -   stwu   r1,-8(r1)      /* Save back chain and move SP */
> -   lis   r0,RESET_VECTOR at h   /* Address of reset vector */
> -   ori   r0,r0,RESET_VECTOR at l
> -   stwu   r1,-8(r1)      /* Save back chain and move SP */
> -   stw   r0,+12(r1)      /* Save return addr (underflow vect) */
> +   stw   r0,0(r3)   /* Terminate Back Chain */
> +   stw   r0,+4(r3)   /* NULL return address. */
> +   mr   r1,r3      /* Transfer to SP(r1) */
>
>     GET_GOT
>     bl   cpu_init_early_f
> --
> 1.7.3.4
>
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