diff mbox series

[V4,4/7] driver/perf/arm_pmu_platform: Add support for BRBE attributes detection

Message ID 20221017055713.451092-5-anshuman.khandual@arm.com
State New
Headers
Series arm64/perf: Enable branch stack sampling |

Commit Message

Anshuman Khandual Oct. 17, 2022, 5:57 a.m. UTC 
  This adds arm pmu infrastrure to probe BRBE implementation's attributes via
driver exported callbacks later. The actual BRBE feature detection will be
added by the driver itself.

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.

Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
 drivers/perf/arm_pmu_platform.c | 34 +++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
diff mbox series

Patch

diff --git a/drivers/perf/arm_pmu_platform.c b/drivers/perf/arm_pmu_platform.c
index 933b96e243b8..acdc445081aa 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");