Re: [PATCH 03/18] arm: fixups: add barriers, actually set MAIR

[Christoffer Dall <christoffer.dall@linaro.org>]

On Sun, Feb 01, 2015 at 07:34:31PM +0100, Andrew Jones wrote:
> Sprinkle in some more isbs after context-changing operations,
> as the ARM ARM states we should. I haven't seen any problems
> without them, but we should do it right. Also, *actually* set
> the MAIR in asm_mmu_enable. We were reading, not writing...
> Luckily this was just spotted while adding the isbs, rather
> than leading to a nightmare debug session some day...
> 
> Signed-off-by: Andrew Jones <drjones@redhat.com>
> ---
>  arm/cstart.S        | 8 ++++++--
>  lib/arm/processor.c | 1 +
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/arm/cstart.S b/arm/cstart.S
> index da496e9eae7e0..39fac8f1e1bd8 100644
> --- a/arm/cstart.S
> +++ b/arm/cstart.S
> @@ -50,6 +50,7 @@ start:
>  .macro set_mode_stack mode, stack
>  	add	\stack, #S_FRAME_SIZE
>  	msr	cpsr_c, #(\mode | PSR_I_BIT | PSR_F_BIT)
> +	isb
>  	mov	sp, \stack
>  .endm
>  
> @@ -70,6 +71,7 @@ exceptions_init:
>  	set_mode_stack	FIQ_MODE, r1
>  
>  	msr	cpsr_cxsf, r2		@ back to svc mode
> +	isb
>  	mov	pc, lr
>  
I don't think you really need those after the cpsr, but whatever.

-Christoffer