static int arm_spe_pmu_event_init()

in arm_spe_pmu.c [669:720]

• 34 lines of code
• 15 McCabe index (conditional complexity)

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) & arm_spe_pmsevfr_res0(spe_pmu->pmsver))
		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, just force the user to specify
	 * a sample period.
	 */
	if (attr->freq)
		return -EINVAL;

	reg = arm_spe_event_to_pmsfcr(event);
	if ((reg & BIT(SYS_PMSFCR_EL1_FE_SHIFT)) &&
	    !(spe_pmu->features & SPE_PMU_FEAT_FILT_EVT))
		return -EOPNOTSUPP;

	if ((reg & BIT(SYS_PMSFCR_EL1_FT_SHIFT)) &&
	    !(spe_pmu->features & SPE_PMU_FEAT_FILT_TYP))
		return -EOPNOTSUPP;

	if ((reg & BIT(SYS_PMSFCR_EL1_FL_SHIFT)) &&
	    !(spe_pmu->features & SPE_PMU_FEAT_FILT_LAT))
		return -EOPNOTSUPP;

	reg = arm_spe_event_to_pmscr(event);
	if (!perfmon_capable() &&
	    (reg & (BIT(SYS_PMSCR_EL1_PA_SHIFT) |
		    BIT(SYS_PMSCR_EL1_CX_SHIFT) |
		    BIT(SYS_PMSCR_EL1_PCT_SHIFT))))
		return -EACCES;

	return 0;
}