Merge patch series "drivers: perf: fix crash with the legacy riscv driver"

Vadim Shakirov <vadim.shakirov@syntacore.com> says:

This series fix crash with the legacy riscv driver when configs:
CONFIG_RISCV_PMU_LEGACY=y and CONFIG_RISCV_PMU_SBI=n and you try
to perf record

* b4-shazam-lts:
  drivers: perf: ctr_get_width function for legacy is not defined
  drivers: perf: added capabilities for legacy PMU

Link: https://lore.kernel.org/r/20240227170002.188671-1-vadim.shakirov@syntacore.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Author: palmer-dabbelt

drivers/perf/riscv_pmu.c

@@ -150,19 +150,11 @@ u64 riscv_pmu_ctr_get_width_mask(struct perf_event *event)
 	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
 	struct hw_perf_event *hwc = &event->hw;
 
-	if (!rvpmu->ctr_get_width)
-	/**
-	 * If the pmu driver doesn't support counter width, set it to default
-	 * maximum allowed by the specification.
-	 */
-		cwidth = 63;
-	else {
-		if (hwc->idx == -1)
-			/* Handle init case where idx is not initialized yet */
-			cwidth = rvpmu->ctr_get_width(0);
-		else
-			cwidth = rvpmu->ctr_get_width(hwc->idx);
-	}
+	if (hwc->idx == -1)
+		/* Handle init case where idx is not initialized yet */
+		cwidth = rvpmu->ctr_get_width(0);
+	else
+		cwidth = rvpmu->ctr_get_width(hwc->idx);
 
 	return GENMASK_ULL(cwidth, 0);
 }

drivers/perf/riscv_pmu_legacy.c

@@ -37,6 +37,12 @@ static int pmu_legacy_event_map(struct perf_event *event, u64 *config)
 	return pmu_legacy_ctr_get_idx(event);
 }
 
+/* cycle & instret are always 64 bit, one bit less according to SBI spec */
+static int pmu_legacy_ctr_get_width(int idx)
+{
+	return 63;
+}
+
 static u64 pmu_legacy_read_ctr(struct perf_event *event)
 {
 	struct hw_perf_event *hwc = &event->hw;
@@ -111,12 +117,14 @@ static void pmu_legacy_init(struct riscv_pmu *pmu)
 	pmu->ctr_stop = NULL;
 	pmu->event_map = pmu_legacy_event_map;
 	pmu->ctr_get_idx = pmu_legacy_ctr_get_idx;
-	pmu->ctr_get_width = NULL;
+	pmu->ctr_get_width = pmu_legacy_ctr_get_width;
 	pmu->ctr_clear_idx = NULL;
 	pmu->ctr_read = pmu_legacy_read_ctr;
 	pmu->event_mapped = pmu_legacy_event_mapped;
 	pmu->event_unmapped = pmu_legacy_event_unmapped;
 	pmu->csr_index = pmu_legacy_csr_index;
+	pmu->pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
+	pmu->pmu.capabilities |= PERF_PMU_CAP_NO_EXCLUDE;
 
 	perf_pmu_register(&pmu->pmu, "cpu", PERF_TYPE_RAW);
 }