Subject: Re: [PATCH 2/2] powerpc/perf: support new BHRB filtering modes

From: Anshuman Khandual <[email-masked]>
Date: Mon, 26 Dec 2016 10:36:34 +0530

On 12/24/2016 11:32 AM, Madhavan Srinivasan wrote:
> Add support for new BHRB filtering modes in
> power9. Patch updates the some of the branch types
> based on "Programming Note" information from
> PowerISA v3.0 "BHRB Filtering" section.

Please reformat, reword, align the commit paragraph and provide more details.

> 
> Signed-off-by: Madhavan Srinivasan <[email-masked]>
> ---
>  arch/powerpc/perf/power9-pmu.c | 33 +++++++++++++++++++++++++++------
>  1 file changed, 27 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/powerpc/perf/power9-pmu.c b/arch/powerpc/perf/power9-pmu.c
> index 56ad09801fff..7165f18934df 100644
> --- a/arch/powerpc/perf/power9-pmu.c
> +++ b/arch/powerpc/perf/power9-pmu.c
> @@ -102,6 +102,11 @@ enum {
>  #define POWER9_MMCRA_IFM1		0x0000000040000000UL
>  #define POWER9_MMCRA_IFM2		0x0000000080000000UL
>  #define POWER9_MMCRA_IFM3		0x00000000C0000000UL
> +#define POWER9_MMCRA_FJ			0x0000000100000000UL
> +#define POWER9_MMCRA_FR			0x0000000200000000UL
> +#define POWER9_MMCRA_FC			0x0000000400000000UL
> +#define POWER9_MMCRA_FU			0x0000000800000000UL
> +#define POWER9_MMCRA_FD			0x0000001000000000UL

This requires more explanation on what kind of filtering they do and how.
Also it will be a good idea to explain the existing IFM1, IFM2, IFM3
filters as well.

> 
>  /* PowerISA v2.07 format attribute structure*/
>  extern struct attribute_group isa207_pmu_format_group;
> @@ -240,14 +245,30 @@ static u64 power9_bhrb_filter_map(u64 branch_sample_type)
>  		return pmu_bhrb_filter;
> 
>  	/* Invalid branch filter options - HW does not support */
> -	if (branch_sample_type & PERF_SAMPLE_BRANCH_ANY_RETURN)
> -		return -1;
> +	if (branch_sample_type & PERF_SAMPLE_BRANCH_ANY_RETURN) {
> +		pmu_bhrb_filter = POWER9_MMCRA_FC | POWER9_MMCRA_FJ;
> +		return pmu_bhrb_filter;
> +	}
> +
> +	if (branch_sample_type & PERF_SAMPLE_BRANCH_IND_CALL) {
> +		pmu_bhrb_filter = POWER9_MMCRA_FD | POWER9_MMCRA_FR | POWER9_MMCRA_FJ;
> +		return pmu_bhrb_filter;
> +	}
> +
> +	if (branch_sample_type & PERF_SAMPLE_BRANCH_COND) {
> +		pmu_bhrb_filter = POWER9_MMCRA_FU;
> +		return pmu_bhrb_filter;
> +	}
> 
> -	if (branch_sample_type & PERF_SAMPLE_BRANCH_IND_CALL)
> -		return -1;
> +	if (branch_sample_type & PERF_SAMPLE_BRANCH_IND_JUMP) {
> +		pmu_bhrb_filter = POWER9_MMCRA_FD | POWER9_MMCRA_FC | POWER9_MMCRA_FR;
> +		return pmu_bhrb_filter;
> +	}
> 
> -	if (branch_sample_type & PERF_SAMPLE_BRANCH_CALL)
> -		return -1;
> +	if (branch_sample_type & PERF_SAMPLE_BRANCH_CALL) {
> +		pmu_bhrb_filter = POWER9_MMCRA_FC;
> +		return pmu_bhrb_filter;
> +	}

May be we can define something like POWER9_BHRB_FILTER_BRANCH_IND_JUMP as
(POWER9_MMCRA_FD | POWER9_MMCRA_FC | POWER9_MMCRA_FR) for all the filters
and use it instead.