linux-kernel - Re: [PATCH v5 1/3] arm64: perf: Include threshold control fields in PMEVTYPER mask

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Message-ID: <ce58fda9-e666-4298-a996-eb0cff6b41a6@arm.com>
Date:   Tue, 21 Nov 2023 10:15:02 +0000
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     James Clark <james.clark@....com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org, will@...nel.org,
        mark.rutland@....com
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Jonathan Corbet <corbet@....net>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/3] arm64: perf: Include threshold control fields in
 PMEVTYPER mask

On 13/11/2023 11:25, James Clark wrote:
> FEAT_PMUv3_TH (Armv8.8) adds two new fields to PMEVTYPER, so include
> them in the mask. These aren't writable on 32 bit kernels as they are in
> the high part of the register, so only include them for arm64.
> 
> It would be difficult to do this statically in the asm header files for
> each platform without resulting in circular includes or #ifdefs inline
> in the code. For that reason the ARMV8_PMU_EVTYPE_MASK definition has
> been removed and the mask is constructed programmatically.
> 
> Signed-off-by: James Clark <james.clark@....com>

Reviewed-by: Suzuki K Poulose <suzuki.poulose@....com>


> ---
>   drivers/perf/arm_pmuv3.c       | 9 ++++++++-
>   include/linux/perf/arm_pmuv3.h | 3 ++-
>   2 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c
> index 6ca7be05229c..1d40d794f5e4 100644
> --- a/drivers/perf/arm_pmuv3.c
> +++ b/drivers/perf/arm_pmuv3.c
> @@ -555,8 +555,15 @@ static void armv8pmu_write_counter(struct perf_event *event, u64 value)
>   static inline void armv8pmu_write_evtype(int idx, u32 val)
>   {
>   	u32 counter = ARMV8_IDX_TO_COUNTER(idx);
> +	unsigned long mask = ARMV8_PMU_EVTYPE_EVENT |
> +			     ARMV8_PMU_INCLUDE_EL2 |
> +			     ARMV8_PMU_EXCLUDE_EL0 |
> +			     ARMV8_PMU_EXCLUDE_EL1;
>   
> -	val &= ARMV8_PMU_EVTYPE_MASK;
> +	if (IS_ENABLED(CONFIG_ARM64))
> +		mask |= ARMV8_PMU_EVTYPE_TC | ARMV8_PMU_EVTYPE_TH;
> +
> +	val &= mask;
>   	write_pmevtypern(counter, val);
>   }
>   
> diff --git a/include/linux/perf/arm_pmuv3.h b/include/linux/perf/arm_pmuv3.h
> index 9c226adf938a..ddd1fec86739 100644
> --- a/include/linux/perf/arm_pmuv3.h
> +++ b/include/linux/perf/arm_pmuv3.h
> @@ -228,7 +228,8 @@
>   /*
>    * PMXEVTYPER: Event selection reg
>    */
> -#define ARMV8_PMU_EVTYPE_MASK	0xc800ffff	/* Mask for writable bits */
> +#define ARMV8_PMU_EVTYPE_TH	GENMASK(43, 32)
> +#define ARMV8_PMU_EVTYPE_TC	GENMASK(63, 61)
>   #define ARMV8_PMU_EVTYPE_EVENT	0xffff		/* Mask for EVENT bits */
>   
>   /*