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Message-Id: <542787fd188ea15ef41c53d557989c962ed44771.1755096883.git.robin.murphy@arm.com>
Date: Wed, 13 Aug 2025 18:01:10 +0100
From: Robin Murphy <robin.murphy@....com>
To: peterz@...radead.org,
mingo@...hat.com,
will@...nel.org,
mark.rutland@....com,
acme@...nel.org,
namhyung@...nel.org,
alexander.shishkin@...ux.intel.com,
jolsa@...nel.org,
irogers@...gle.com,
adrian.hunter@...el.com,
kan.liang@...ux.intel.com
Cc: linux-perf-users@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-alpha@...r.kernel.org,
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linux-arm-kernel@...ts.infradead.org,
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loongarch@...ts.linux.dev,
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Subject: [PATCH 18/19] perf: Introduce positive capability for raw events
Only a handful of CPU PMUs accept PERF_TYPE_{RAW,HARDWARE,HW_CACHE}
events without registering themselves as PERF_TYPE_RAW in the first
place. Add an explicit opt-in for these special cases, so that we can
make life easier for every other driver (and probably also speed up the
slow-path search) by having perf_try_init_event() do the basic type
checking to cover the majority of cases.
Signed-off-by: Robin Murphy <robin.murphy@....com>
---
A further possibility is to automatically add the cap to PERF_TYPE_RAW
PMUs in perf_pmu_register() to have a single point-of-use condition; I'm
undecided...
---
arch/s390/kernel/perf_cpum_cf.c | 1 +
arch/s390/kernel/perf_pai_crypto.c | 2 +-
arch/s390/kernel/perf_pai_ext.c | 2 +-
arch/x86/events/core.c | 2 +-
drivers/perf/arm_pmu.c | 1 +
include/linux/perf_event.h | 1 +
kernel/events/core.c | 15 +++++++++++++++
7 files changed, 21 insertions(+), 3 deletions(-)
diff --git a/arch/s390/kernel/perf_cpum_cf.c b/arch/s390/kernel/perf_cpum_cf.c
index 1a94e0944bc5..782ab755ddd4 100644
--- a/arch/s390/kernel/perf_cpum_cf.c
+++ b/arch/s390/kernel/perf_cpum_cf.c
@@ -1054,6 +1054,7 @@ static void cpumf_pmu_del(struct perf_event *event, int flags)
/* Performance monitoring unit for s390x */
static struct pmu cpumf_pmu = {
.task_ctx_nr = perf_sw_context,
+ .capabilities = PERF_PMU_CAP_RAW_EVENTS,
.pmu_enable = cpumf_pmu_enable,
.pmu_disable = cpumf_pmu_disable,
.event_init = cpumf_pmu_event_init,
diff --git a/arch/s390/kernel/perf_pai_crypto.c b/arch/s390/kernel/perf_pai_crypto.c
index a64b6b056a21..b5b6d8b5d943 100644
--- a/arch/s390/kernel/perf_pai_crypto.c
+++ b/arch/s390/kernel/perf_pai_crypto.c
@@ -569,7 +569,7 @@ static const struct attribute_group *paicrypt_attr_groups[] = {
/* Performance monitoring unit for mapped counters */
static struct pmu paicrypt = {
.task_ctx_nr = perf_hw_context,
- .capabilities = PERF_PMU_CAP_SAMPLING,
+ .capabilities = PERF_PMU_CAP_SAMPLING | PERF_PMU_CAP_RAW_EVENTS,
.event_init = paicrypt_event_init,
.add = paicrypt_add,
.del = paicrypt_del,
diff --git a/arch/s390/kernel/perf_pai_ext.c b/arch/s390/kernel/perf_pai_ext.c
index 1261f80c6d52..bcd28c38da70 100644
--- a/arch/s390/kernel/perf_pai_ext.c
+++ b/arch/s390/kernel/perf_pai_ext.c
@@ -595,7 +595,7 @@ static const struct attribute_group *paiext_attr_groups[] = {
/* Performance monitoring unit for mapped counters */
static struct pmu paiext = {
.task_ctx_nr = perf_hw_context,
- .capabilities = PERF_PMU_CAP_SAMPLING,
+ .capabilities = PERF_PMU_CAP_SAMPLING | PERF_PMU_CAP_RAW_EVENTS,
.event_init = paiext_event_init,
.add = paiext_add,
.del = paiext_del,
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 789dfca2fa67..764728bb80ae 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2697,7 +2697,7 @@ static bool x86_pmu_filter(struct pmu *pmu, int cpu)
}
static struct pmu pmu = {
- .capabilities = PERF_PMU_CAP_SAMPLING,
+ .capabilities = PERF_PMU_CAP_SAMPLING | PERF_PMU_CAP_RAW_EVENTS,
.pmu_enable = x86_pmu_enable,
.pmu_disable = x86_pmu_disable,
diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index 72d8f38d0aa5..bc772a3bf411 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -877,6 +877,7 @@ struct arm_pmu *armpmu_alloc(void)
* specific PMU.
*/
.capabilities = PERF_PMU_CAP_SAMPLING |
+ PERF_PMU_CAP_RAW_EVENTS |
PERF_PMU_CAP_EXTENDED_REGS |
PERF_PMU_CAP_EXTENDED_HW_TYPE,
};
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 183b7c48b329..c6ad036c0037 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -305,6 +305,7 @@ struct perf_event_pmu_context;
#define PERF_PMU_CAP_EXTENDED_HW_TYPE 0x0100
#define PERF_PMU_CAP_AUX_PAUSE 0x0200
#define PERF_PMU_CAP_AUX_PREFER_LARGE 0x0400
+#define PERF_PMU_CAP_RAW_EVENTS 0x0800
/**
* pmu::scope
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 71b2a6730705..2ecee76d2ae2 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -12556,11 +12556,26 @@ static inline bool has_extended_regs(struct perf_event *event)
(event->attr.sample_regs_intr & PERF_REG_EXTENDED_MASK);
}
+static bool is_raw_pmu(const struct pmu *pmu)
+{
+ return pmu->type == PERF_TYPE_RAW ||
+ pmu->capabilities & PERF_PMU_CAP_RAW_EVENTS;
+}
+
static int perf_try_init_event(struct pmu *pmu, struct perf_event *event)
{
struct perf_event_context *ctx = NULL;
int ret;
+ /*
+ * Before touching anything, we can safely skip:
+ * - any event for a specific PMU which is not this one
+ * - any common event if this PMU doesn't support them
+ */
+ if (event->attr.type != pmu->type &&
+ (event->attr.type >= PERF_TYPE_MAX || is_raw_pmu(pmu)))
+ return -ENOENT;
+
if (!try_module_get(pmu->module))
return -ENODEV;
--
2.39.2.101.g768bb238c484.dirty
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