linux-kernel - Re: [PATCH V2 3/4] arm64/perf: Assert all platform event flags are within PERF_EVENT_FLAG

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Message-ID: <3ad268df-f6fd-a899-ce0e-131b5fdfeae8@arm.com>
Date:   Mon, 5 Sep 2022 10:10:03 +0100
From:   James Clark <james.clark@....com>
To:     Anshuman Khandual <anshuman.khandual@....com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, x86@...nel.org,
        Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        peterz@...radead.org
Subject: Re: [PATCH V2 3/4] arm64/perf: Assert all platform event flags are
 within PERF_EVENT_FLAG_ARCH



On 05/09/2022 06:42, Anshuman Khandual wrote:
> Ensure all platform specific event flags are within PERF_EVENT_FLAG_ARCH.
> 
> Cc: Will Deacon <will@...nel.org>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> Cc: Jiri Olsa <jolsa@...nel.org>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-perf-users@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
> ---
>  drivers/perf/arm_spe_pmu.c   | 4 +++-
>  include/linux/perf/arm_pmu.h | 9 +++++----
>  2 files changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c
> index b65a7d9640e1..db8a0a841062 100644
> --- a/drivers/perf/arm_spe_pmu.c
> +++ b/drivers/perf/arm_spe_pmu.c
> @@ -44,7 +44,9 @@
>   * This allows us to perform the check, i.e, perfmon_capable(),
>   * in the context of the event owner, once, during the event_init().
>   */
> -#define SPE_PMU_HW_FLAGS_CX			BIT(0)
> +#define SPE_PMU_HW_FLAGS_CX			0x00001
> +
> +static_assert((PERF_EVENT_FLAG_ARCH & SPE_PMU_HW_FLAGS_CX) == SPE_PMU_HW_FLAGS_CX);
>  
>  static void set_spe_event_has_cx(struct perf_event *event)
>  {
> diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
> index 0407a38b470a..0356cb6a215d 100644
> --- a/include/linux/perf/arm_pmu.h
> +++ b/include/linux/perf/arm_pmu.h
> @@ -24,10 +24,11 @@
>  /*
>   * ARM PMU hw_event flags
>   */
> -/* Event uses a 64bit counter */
> -#define ARMPMU_EVT_64BIT		1
> -/* Event uses a 47bit counter */
> -#define ARMPMU_EVT_47BIT		2
> +#define ARMPMU_EVT_64BIT		0x00001 /* Event uses a 64bit counter */
> +#define ARMPMU_EVT_47BIT		0x00002 /* Event uses a 47bit counter */
> +

Minor nit:

I don't think changing the definitions to hex adds anything except more
noise in the git blame.

Either way, for the whole set:

Reviewed-by: James Clark <james.clark@....com>

> +static_assert((PERF_EVENT_FLAG_ARCH & ARMPMU_EVT_64BIT) == ARMPMU_EVT_64BIT);
> +static_assert((PERF_EVENT_FLAG_ARCH & ARMPMU_EVT_47BIT) == ARMPMU_EVT_47BIT);
>  
>  #define HW_OP_UNSUPPORTED		0xFFFF
>  #define C(_x)				PERF_COUNT_HW_CACHE_##_x