Subject: Re: [PATCH 5/6] powerpc: Macros for saving/restore PPR

From: Benjamin Herrenschmidt <[email-masked]>
Date: Mon, 10 Sep 2012 14:24:04 +1000

On Sun, 2012-09-09 at 04:43 -0700, Haren Myneni wrote:
> Several macros are defined for saving and restore user defined PPR value.
> 
> Signed-off-by: Haren Myneni <[email-masked]>
> ---
>  arch/powerpc/include/asm/exception-64s.h |   35 ++++++++++++++++++++++++++++++
>  arch/powerpc/include/asm/reg.h           |    1 +
>  2 files changed, 36 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
> index bfd3f1f..618fd18 100644
> --- a/arch/powerpc/include/asm/exception-64s.h
> +++ b/arch/powerpc/include/asm/exception-64s.h
> @@ -62,6 +62,41 @@
>  #define EXC_HV	H
>  #define EXC_STD
>  
> +/*
> + * PPR save/restore macros - Used on P7 or later processors
> + */
> +#define SAVE_PPR(area, ra, rb)						\
> +BEGIN_FTR_SECTION_NESTED(940)						\
> +	ld	ra,area+EX_PPR(r13);	/* Read PPR from paca */	\
> +	clrrdi	rb,r1,THREAD_SHIFT;	/* thread_info struct */	\
> +	std	ra,TI_PPR(rb);		/* Save PPR in thread_info */	\
> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,940)

Why the thread info and not the thread struct ?

Cheers,
Ben.

> +#define RESTORE_PPR(ra,rb)						\
> +BEGIN_FTR_SECTION_NESTED(941)						\
> +	clrrdi	ra,r1,THREAD_SHIFT;					\
> +	ld	rb,TI_PPR(ra);		/* Read PPR from thread_info */	\
> +	mtspr	SPRN_PPR,rb;		/* Restore PPR */		\
> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,941)
> +
> +#define RESTORE_PPR_PACA(area,ra)					\
> +BEGIN_FTR_SECTION_NESTED(942)						\
> +	ld	ra,area+EX_PPR(r13);					\
> +	mtspr	SPRN_PPR,ra;						\
> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,942)
> +
> +#define HMT_MEDIUM_NO_PPR						\
> +BEGIN_FTR_SECTION_NESTED(944)						\
> +	HMT_MEDIUM;							\
> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,0,944)  /*non P7*/		
> +
> +#define HMT_MEDIUM_HAS_PPR(area, ra)					\
> +BEGIN_FTR_SECTION_NESTED(943)						\
> +	mfspr	ra,SPRN_PPR;						\
> +	std	ra,area+EX_PPR(r13);					\
> +	HMT_MEDIUM;							\
> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,943) /* P7 */
> +
>  #define __EXCEPTION_PROLOG_1(area, extra, vec)				\
>  	GET_PACA(r13);							\
>  	std	r9,area+EX_R9(r13);	/* save r9 - r12 */		\
> diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
> index 6386086..dff2f89 100644
> --- a/arch/powerpc/include/asm/reg.h
> +++ b/arch/powerpc/include/asm/reg.h
> @@ -284,6 +284,7 @@
>  #define SPRN_DBAT6U	0x23C	/* Data BAT 6 Upper Register */
>  #define SPRN_DBAT7L	0x23F	/* Data BAT 7 Lower Register */
>  #define SPRN_DBAT7U	0x23E	/* Data BAT 7 Upper Register */
> +#define SPRN_PPR	0x380	/* SMT Thread status Register */
>  
>  #define SPRN_DEC	0x016		/* Decrement Register */
>  #define SPRN_DER	0x095		/* Debug Enable Regsiter */