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Date: Wed, 9 Jun 2021 17:20:53 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...hat.com>, Leo Yan <leo.yan@...aro.org>,
Kan Liang <kan.liang@...ux.intel.com>, x86@...nel.org,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] perf/x86: Add new event for AUX output counter index
PEBS-via-PT records contain a mask of applicable counters. To identify
which event belongs to which counter, a side-band event is needed. Until
now, there has been no side-band event, and consequently users were limited
to using a single event.
Add such a side-band event. Note the event is optimised to output only
when the counter index changes for an event. That works only so long as
all PEBS-via-PT events are scheduled together, which they are for a
recording session because they are in a single group.
Also no attribute bit is used to select the new event, so a new
kernel is not compatible with older perf tools. The assumption
being that PEBS-via-PT is sufficiently esoteric that users will not
be troubled by this.
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
Reviewed-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Reviewed-by: Andi Kleen <ak@...ux.intel.com>
---
arch/x86/events/core.c | 1 +
arch/x86/events/intel/ds.c | 16 ++++++++++++++++
include/linux/perf_event.h | 2 ++
include/uapi/linux/perf_event.h | 15 +++++++++++++++
kernel/events/core.c | 30 ++++++++++++++++++++++++++++++
5 files changed, 64 insertions(+)
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 8f71dd72ef95..30d0d18eb4b6 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -660,6 +660,7 @@ static int __x86_pmu_event_init(struct perf_event *event)
event->destroy = hw_perf_event_destroy;
event->hw.idx = -1;
+ event->hw.idx_reported = -1;
event->hw.last_cpu = -1;
event->hw.last_tag = ~0ULL;
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index 1ec8fd311f38..d4c149b6e82b 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1182,6 +1182,20 @@ static void intel_pmu_pebs_via_pt_disable(struct perf_event *event)
cpuc->pebs_enabled &= ~PEBS_VIA_PT_MASK;
}
+static void intel_pmu_report_aux_output_id(struct perf_event *event)
+{
+ struct hw_perf_event *hwc = &event->hw;
+
+ /*
+ * So long as all PEBS-via-PT events for a recording session are
+ * scheduled together, then only changes to hwc->idx need be reported.
+ */
+ if (hwc->idx != hwc->idx_reported) {
+ hwc->idx_reported = hwc->idx;
+ perf_report_aux_output_id(event, hwc->idx);
+ }
+}
+
static void intel_pmu_pebs_via_pt_enable(struct perf_event *event)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
@@ -1191,6 +1205,8 @@ static void intel_pmu_pebs_via_pt_enable(struct perf_event *event)
if (!is_pebs_pt(event))
return;
+ intel_pmu_report_aux_output_id(event);
+
if (!(event->hw.flags & PERF_X86_EVENT_LARGE_PEBS))
cpuc->pebs_enabled |= PEBS_PMI_AFTER_EACH_RECORD;
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index f5a6a2f069ed..18bfa05537ab 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -141,6 +141,7 @@ struct hw_perf_event {
unsigned long event_base;
int event_base_rdpmc;
int idx;
+ int idx_reported;
int last_cpu;
int flags;
@@ -1397,6 +1398,7 @@ perf_event_addr_filters(struct perf_event *event)
}
extern void perf_event_addr_filters_sync(struct perf_event *event);
+extern void perf_report_aux_output_id(struct perf_event *event, u64 hw_id);
extern int perf_output_begin(struct perf_output_handle *handle,
struct perf_sample_data *data,
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index f92880a15645..c89535de1ec8 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -1141,6 +1141,21 @@ enum perf_event_type {
*/
PERF_RECORD_TEXT_POKE = 20,
+ /*
+ * Data written to the AUX area by hardware due to aux_output, may need
+ * to be matched to the event by an architecture-specific hardware ID.
+ * This records the hardware ID, but requires sample_id to provide the
+ * event ID. e.g. Intel PT uses this record to disambiguate PEBS-via-PT
+ * records from multiple events.
+ *
+ * struct {
+ * struct perf_event_header header;
+ * u64 hw_id;
+ * struct sample_id sample_id;
+ * };
+ */
+ PERF_RECORD_AUX_OUTPUT_HW_ID = 21,
+
PERF_RECORD_MAX, /* non-ABI */
};
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 6fee4a7e88d7..bf98c8932ae2 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9055,6 +9055,36 @@ static void perf_log_itrace_start(struct perf_event *event)
perf_output_end(&handle);
}
+void perf_report_aux_output_id(struct perf_event *event, u64 hw_id)
+{
+ struct perf_output_handle handle;
+ struct perf_sample_data sample;
+ struct perf_aux_event {
+ struct perf_event_header header;
+ u64 hw_id;
+ } rec;
+ int ret;
+
+ if (event->parent)
+ event = event->parent;
+
+ rec.header.type = PERF_RECORD_AUX_OUTPUT_HW_ID;
+ rec.header.misc = 0;
+ rec.header.size = sizeof(rec);
+ rec.hw_id = hw_id;
+
+ perf_event_header__init_id(&rec.header, &sample, event);
+ ret = perf_output_begin(&handle, &sample, event, rec.header.size);
+
+ if (ret)
+ return;
+
+ perf_output_put(&handle, rec);
+ perf_event__output_id_sample(event, &handle, &sample);
+
+ perf_output_end(&handle);
+}
+
static int
__perf_event_account_interrupt(struct perf_event *event, int throttle)
{
--
2.17.1
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