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Message-ID: <YfGCgwlk6wHS/OYe@robh.at.kernel.org>
Date: Wed, 26 Jan 2022 11:18:59 -0600
From: Rob Herring <robh@...nel.org>
To: Anshuman Khandual <anshuman.khandual@....com>
Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
linux-perf-users@...r.kernel.org
Subject: Re: [RFC V1 05/11] arm64/perf: Detect support for BRBE
On Mon, Jan 24, 2022 at 10:00:47AM +0530, Anshuman Khandual wrote:
> CPU specific BRBE entries, cycle count, format support gets detected during
> PMU init. This information gets saved in per-cpu struct pmu_hw_events which
> later helps in operating BRBE during a perf event context.
Another NOP commit. The subject says 'arm64' and that we detect BRBE
support. This patch neither touches arm64 code nor detects anything.
>
> Cc: Will Deacon <will@...nel.org>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
> ---
> drivers/perf/arm_pmu_platform.c | 34 +++++++++++++++++++++++++++++++++
> 1 file changed, 34 insertions(+)
>
> diff --git a/drivers/perf/arm_pmu_platform.c b/drivers/perf/arm_pmu_platform.c
> index 513de1f54e2d..800e4a6e8bc3 100644
> --- a/drivers/perf/arm_pmu_platform.c
> +++ b/drivers/perf/arm_pmu_platform.c
> @@ -172,6 +172,36 @@ static int armpmu_request_irqs(struct arm_pmu *armpmu)
> return err;
> }
>
> +static void arm_brbe_probe_cpu(void *info)
> +{
> + struct pmu_hw_events *hw_events;
> + struct arm_pmu *armpmu = info;
> +
> + /*
> + * Return from here, if BRBE driver has not been
> + * implemented for this PMU. This helps prevent
> + * kernel crash later when brbe_probe() will be
> + * called on the PMU.
> + */
> + if (!armpmu->brbe_probe)
> + return;
> +
> + hw_events = per_cpu_ptr(armpmu->hw_events, smp_processor_id());
> + armpmu->brbe_probe(hw_events);
> +}
> +
> +static int armpmu_request_brbe(struct arm_pmu *armpmu)
> +{
> + int cpu, err = 0;
> +
> + for_each_cpu(cpu, &armpmu->supported_cpus) {
> + err = smp_call_function_single(cpu, arm_brbe_probe_cpu, armpmu, 1);
> + if (err)
> + return err;
> + }
> + return err;
> +}
> +
> static void armpmu_free_irqs(struct arm_pmu *armpmu)
> {
> int cpu;
> @@ -229,6 +259,10 @@ int arm_pmu_device_probe(struct platform_device *pdev,
> if (ret)
> goto out_free_irqs;
>
> + ret = armpmu_request_brbe(pmu);
> + if (ret)
> + goto out_free_irqs;
> +
> ret = armpmu_register(pmu);
> if (ret) {
> dev_err(dev, "failed to register PMU devices!\n");
> --
> 2.25.1
>
>
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