[PATCH 02/10] perf: Add capability for common event support

From: Robin Murphy
Date: Tue Mar 12 2024 - 13:35:03 EST


Many PMUs do not support common hardware/cache/etc. events and only
handle their own PMU-specific events. Since this only depends on
matching the event and PMU types, it's a prime candidate for a core
capability to save more event_init boilerplate in drivers.

Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
---
include/linux/perf_event.h | 1 +
kernel/events/core.c | 5 +++++
2 files changed, 6 insertions(+)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index d2a15c0c6f8a..983201f21dd2 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -291,6 +291,7 @@ struct perf_event_pmu_context;
#define PERF_PMU_CAP_NO_EXCLUDE 0x0040
#define PERF_PMU_CAP_AUX_OUTPUT 0x0080
#define PERF_PMU_CAP_EXTENDED_HW_TYPE 0x0100
+#define PERF_PMU_CAP_NO_COMMON_EVENTS 0x0200

struct perf_output_handle;

diff --git a/kernel/events/core.c b/kernel/events/core.c
index f0f0f71213a1..7ad80826c218 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -11649,6 +11649,11 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event)
struct perf_event_context *ctx = NULL;
int ret;

+ /* Short-circuit if we know the PMU won't want this event */
+ if (pmu->capabilities & PERF_PMU_CAP_NO_COMMON_EVENTS &&
+ event->attr.type != pmu->type)
+ return -ENOENT;
+
if (!try_module_get(pmu->module))
return -ENODEV;

--
2.39.2.101.g768bb238c484.dirty