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Subject[PATCH 2/6] perf offcpu: Accept allowed sample types only
Date
As offcpu-time event is synthesized at the end, it could not get the
all the sample info. Define OFFCPU_SAMPLE_TYPES for allowed ones and
mask out others in evsel__config() to prevent parse errors.

Because perf sample parsing assumes a specific ordering with the
sample types, setting unsupported one would make it fail to read
data like perf record -d/--data.

Fixes: edc41a1099c2 ("perf record: Enable off-cpu analysis with BPF")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
tools/perf/util/bpf_off_cpu.c | 7 ++++++-
tools/perf/util/evsel.c | 9 +++++++++
tools/perf/util/off_cpu.h | 9 +++++++++
3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
index b73e84a02264..f289b7713598 100644
--- a/tools/perf/util/bpf_off_cpu.c
+++ b/tools/perf/util/bpf_off_cpu.c
@@ -265,6 +265,12 @@ int off_cpu_write(struct perf_session *session)

sample_type = evsel->core.attr.sample_type;

+ if (sample_type & ~OFFCPU_SAMPLE_TYPES) {
+ pr_err("not supported sample type: %llx\n",
+ (unsigned long long)sample_type);
+ return -1;
+ }
+
if (sample_type & (PERF_SAMPLE_ID | PERF_SAMPLE_IDENTIFIER)) {
if (evsel->core.id)
sid = evsel->core.id[0];
@@ -319,7 +325,6 @@ int off_cpu_write(struct perf_session *session)
}
if (sample_type & PERF_SAMPLE_CGROUP)
data.array[n++] = key.cgroup_id;
- /* TODO: handle more sample types */

size = n * sizeof(u64);
data.hdr.size = size;
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index ce499c5da8d7..094b0a9c0bc0 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -48,6 +48,7 @@
#include "util.h"
#include "hashmap.h"
#include "pmu-hybrid.h"
+#include "off_cpu.h"
#include "../perf-sys.h"
#include "util/parse-branch-options.h"
#include <internal/xyarray.h>
@@ -1102,6 +1103,11 @@ static void evsel__set_default_freq_period(struct record_opts *opts,
}
}

+static bool evsel__is_offcpu_event(struct evsel *evsel)
+{
+ return evsel__is_bpf_output(evsel) && !strcmp(evsel->name, OFFCPU_EVENT);
+}
+
/*
* The enable_on_exec/disabled value strategy:
*
@@ -1366,6 +1372,9 @@ void evsel__config(struct evsel *evsel, struct record_opts *opts,
*/
if (evsel__is_dummy_event(evsel))
evsel__reset_sample_bit(evsel, BRANCH_STACK);
+
+ if (evsel__is_offcpu_event(evsel))
+ evsel->core.attr.sample_type &= OFFCPU_SAMPLE_TYPES;
}

int evsel__set_filter(struct evsel *evsel, const char *filter)
diff --git a/tools/perf/util/off_cpu.h b/tools/perf/util/off_cpu.h
index 548008f74d42..2dd67c60f211 100644
--- a/tools/perf/util/off_cpu.h
+++ b/tools/perf/util/off_cpu.h
@@ -1,6 +1,8 @@
#ifndef PERF_UTIL_OFF_CPU_H
#define PERF_UTIL_OFF_CPU_H

+#include <linux/perf_event.h>
+
struct evlist;
struct target;
struct perf_session;
@@ -8,6 +10,13 @@ struct record_opts;

#define OFFCPU_EVENT "offcpu-time"

+#define OFFCPU_SAMPLE_TYPES (PERF_SAMPLE_IDENTIFIER | PERF_SAMPLE_IP | \
+ PERF_SAMPLE_TID | PERF_SAMPLE_TIME | \
+ PERF_SAMPLE_ID | PERF_SAMPLE_CPU | \
+ PERF_SAMPLE_PERIOD | PERF_SAMPLE_CALLCHAIN | \
+ PERF_SAMPLE_CGROUP)
+
+
#ifdef HAVE_BPF_SKEL
int off_cpu_prepare(struct evlist *evlist, struct target *target,
struct record_opts *opts);
--
2.37.0.rc0.161.g10f37bed90-goog
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