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SubjectRe: [PATCH v4 4/5] drivers/perf: Add support for ARMv8.2 Statistical Profiling Extension
On Mon, 5 Jun 2017 16:22:56 +0100
Will Deacon <will.deacon@arm.com> wrote:

> +/* Perf callbacks */
> +static int arm_spe_pmu_event_init(struct perf_event *event)
> +{
> + u64 reg;
> + struct perf_event_attr *attr = &event->attr;
> + struct arm_spe_pmu *spe_pmu = to_spe_pmu(event->pmu);
> +
> + /* This is, of course, deeply driver-specific */
> + if (attr->type != event->pmu->type)
> + return -ENOENT;
> +
> + if (event->cpu >= 0 &&
> + !cpumask_test_cpu(event->cpu, &spe_pmu->supported_cpus))
> + return -ENOENT;
> +
> + if (arm_spe_event_to_pmsevfr(event) & PMSEVFR_EL1_RES0)
> + return -EOPNOTSUPP;
> +
> + if (event->hw.sample_period < spe_pmu->min_period ||
> + event->hw.sample_period & PMSIRR_EL1_IVAL_MASK)
> + return -EOPNOTSUPP;
> +
> + if (attr->exclude_idle)
> + return -EOPNOTSUPP;
> +
> + /*
> + * Feedback-directed frequency throttling doesn't work when we
> + * have a buffer of samples. We'd need to manually count the
> + * samples in the buffer when it fills up and adjust the event
> + * count to reflect that. Instead, force the user to specify a
> + * sample period instead.
> + */
> + if (attr->freq)
> + return -EINVAL;
> +
> + reg = arm_spe_event_to_pmsfcr(event);
> + if ((reg & BIT(PMSFCR_EL1_FE_SHIFT)) &&
> + !(spe_pmu->features & SPE_PMU_FEAT_FILT_EVT))
> + return -EOPNOTSUPP;
> +
> + if ((reg & BIT(PMSFCR_EL1_FT_SHIFT)) &&
> + !(spe_pmu->features & SPE_PMU_FEAT_FILT_TYP))
> + return -EOPNOTSUPP;
> +
> + if ((reg & BIT(PMSFCR_EL1_FL_SHIFT)) &&
> + !(spe_pmu->features & SPE_PMU_FEAT_FILT_LAT))
> + return -EOPNOTSUPP;
> +
> + return 0;
> +}

AFAICT, my comments from the last submission have still not been fully
addressed:

http://lists.infradead.org/pipermail/linux-arm-kernel/2017-May/508027.html

Thanks,

Kim

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