linux-kernel - Re: [PATCH 2/4] perf: arm_cspmu: Support implementation specific filters

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Message-ID: <20230622093338.0000420f@Huawei.com>
Date:   Thu, 22 Jun 2023 09:33:38 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Ilkka Koskinen <ilkka@...amperecomputing.com>
CC:     Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
        Besar Wicaksono <bwicaksono@...dia.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mark Rutland <mark.rutland@....com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/4] perf: arm_cspmu: Support implementation specific
 filters

On Wed, 21 Jun 2023 18:11:39 -0700
Ilkka Koskinen <ilkka@...amperecomputing.com> wrote:

> Generic filters aren't used in all the platforms. Instead, the platforms
> may use different means to filter events. Add support for implementation
> specific filters.

If the specification allows explicitly for non standard ways of controlling filters
it would be good to add a specification reference to this.

Otherwise one question inline.
> 
> Reviewed-by: Besar Wicaksono <bwicaksono@...dia.com>
> Signed-off-by: Ilkka Koskinen <ilkka@...amperecomputing.com>
> ---
>  drivers/perf/arm_cspmu/arm_cspmu.c | 8 ++++++--
>  drivers/perf/arm_cspmu/arm_cspmu.h | 3 +++
>  2 files changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/perf/arm_cspmu/arm_cspmu.c b/drivers/perf/arm_cspmu/arm_cspmu.c
> index 0f517152cb4e..fafd734c3218 100644
> --- a/drivers/perf/arm_cspmu/arm_cspmu.c
> +++ b/drivers/perf/arm_cspmu/arm_cspmu.c
> @@ -117,6 +117,9 @@
>  
>  static unsigned long arm_cspmu_cpuhp_state;
>  
> +static void arm_cspmu_set_ev_filter(struct arm_cspmu *cspmu,
> +				    struct hw_perf_event *hwc, u32 filter);
> +
>  static struct acpi_apmt_node *arm_cspmu_apmt_node(struct device *dev)
>  {
>  	return *(struct acpi_apmt_node **)dev_get_platdata(dev);
> @@ -426,6 +429,7 @@ static int arm_cspmu_init_impl_ops(struct arm_cspmu *cspmu)
>  	CHECK_DEFAULT_IMPL_OPS(impl_ops, event_type);
>  	CHECK_DEFAULT_IMPL_OPS(impl_ops, event_filter);
>  	CHECK_DEFAULT_IMPL_OPS(impl_ops, event_attr_is_visible);
> +	CHECK_DEFAULT_IMPL_OPS(impl_ops, set_ev_filter);
>  
>  	return 0;
>  }
> @@ -792,7 +796,7 @@ static inline void arm_cspmu_set_event(struct arm_cspmu *cspmu,
>  	writel(hwc->config, cspmu->base0 + offset);
>  }
>  
> -static inline void arm_cspmu_set_ev_filter(struct arm_cspmu *cspmu,
> +static void arm_cspmu_set_ev_filter(struct arm_cspmu *cspmu,
>  					   struct hw_perf_event *hwc,
>  					   u32 filter)
>  {
> @@ -826,7 +830,7 @@ static void arm_cspmu_start(struct perf_event *event, int pmu_flags)
>  		arm_cspmu_set_cc_filter(cspmu, filter);
>  	} else {
>  		arm_cspmu_set_event(cspmu, hwc);
> -		arm_cspmu_set_ev_filter(cspmu, hwc, filter);
> +		cspmu->impl.ops.set_ev_filter(cspmu, hwc, filter);

Optional callback so don't you need either provide a default, or check
it isn't null?

>  	}
>  
>  	hwc->state = 0;
> diff --git a/drivers/perf/arm_cspmu/arm_cspmu.h b/drivers/perf/arm_cspmu/arm_cspmu.h
> index 83df53d1c132..d6d88c246a23 100644
> --- a/drivers/perf/arm_cspmu/arm_cspmu.h
> +++ b/drivers/perf/arm_cspmu/arm_cspmu.h
> @@ -101,6 +101,9 @@ struct arm_cspmu_impl_ops {
>  	u32 (*event_type)(const struct perf_event *event);
>  	/* Decode filter value from configs */
>  	u32 (*event_filter)(const struct perf_event *event);
> +	/* Set event filter */
> +	void (*set_ev_filter)(struct arm_cspmu *cspmu,
> +			      struct hw_perf_event *hwc, u32 filter);
>  	/* Hide/show unsupported events */
>  	umode_t (*event_attr_is_visible)(struct kobject *kobj,
>  					 struct attribute *attr, int unused);