Re: [v5][PATCH 1/6] powerpc/book3e: load critical/machine/debug exception stack

[Scott Wood <scottwood@freescale.com>]

On Thu, 2013-06-20 at 18:28 +0800, Tiejun Chen wrote:
> We always alloc critical/machine/debug check exceptions. This is
> different from the normal exception. So we should load these exception
> stack properly like we did for booke.
> 
> Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
> ---
>  arch/powerpc/kernel/exceptions-64e.S |   49 +++++++++++++++++++++++++++++++---
>  1 file changed, 46 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
> index 4b23119..4d8e57f 100644
> --- a/arch/powerpc/kernel/exceptions-64e.S
> +++ b/arch/powerpc/kernel/exceptions-64e.S
> @@ -36,6 +36,37 @@
>   */
>  #define	SPECIAL_EXC_FRAME_SIZE	INT_FRAME_SIZE
>  
> +/* only on book3e */
> +#define DBG_STACK_BASE		dbgirq_ctx
> +#define MC_STACK_BASE		mcheckirq_ctx
> +#define CRIT_STACK_BASE		critirq_ctx
> +
> +#ifdef CONFIG_RELOCATABLE
> +#define LOAD_STACK_BASE(reg, level)			\
> +	tovirt(r2,r2);					\
> +	LOAD_REG_ADDR(reg, level##_STACK_BASE);

Where does r2 come from here, where does it get used, and why do we need
tovirt() on book3e?

-Scott