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

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Message-Id: <feb10873fe9e4e10b5ffbbe8e296c8a45632e3c2.1710257512.git.robin.murphy@arm.com>
Date: Tue, 12 Mar 2024 17:34:04 +0000
From: Robin Murphy <robin.murphy@....com>
To: Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Will Deacon <will@...nel.org>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	x86@...nel.org,
	linux-perf-users@...r.kernel.org,
	jialong.yang@...ngroup.cn
Subject: [PATCH 02/10] perf: Add capability for common event support

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@....com>
---
 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