[PATCH 1/2] perf evsel: Add lazy-initialized probe type detection helpers

[Arnaldo Carvalho de Melo <acme@kernel.org>]

From: Arnaldo Carvalho de Melo <acme@redhat.com>

Several places in perf need to check whether an evsel is a kprobe or
uprobe, which requires looking up the PMU by name via evsel__find_pmu().
This lookup walks the PMU list each time, which is wasteful when the
same evsel is checked repeatedly.

Add evsel__is_kprobe(), evsel__is_uprobe(), and evsel__is_probe() that
resolve the probe type on first call via evsel__pmu_name() and cache
the result in a 3-bit field (probe_type) in struct evsel.  The field
fits in existing padding after the bool fields, so struct size does not
grow.

The enum uses PROBE__UNKNOWN (0) as the uninitialized sentinel —
explicitly set in evsel__init() — so the lookup happens on first use.
PROBE__NOPE (1) caches "not a probe" to avoid repeated negative lookups.

PMU-based probes (kprobe/uprobe PMU) are detected by PMU name.
Ftrace-based dynamic probes (created via tracefs, reported as PMU
"tracepoint") are detected by the __probe_ip field that the kernel
adds to all dynamic probe formats.  This covers kprobes, uprobes, and
fprobes regardless of their group/system name.

Assisted-by: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/evsel.c | 53 +++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/evsel.h | 19 +++++++++++++++
 2 files changed, 72 insertions(+)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 05fa0010c858a51e..ea9fa04429f08a9e 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -254,6 +254,58 @@ const char *evsel__pmu_name(const struct evsel *evsel)
 	return event_type(evsel->core.attr.type);
 }
 
+enum evsel_probe_type {
+	PROBE__UNKNOWN	= 0,
+	PROBE__NOPE	= 1,
+	PROBE__KPROBE	= 2,
+	PROBE__UPROBE	= 3,
+	/*
+	 * Ftrace-based dynamic probes (kprobes/uprobes/fprobes created via
+	 * tracefs) report PMU "tracepoint", not "kprobe"/"uprobe".  Detect
+	 * them by the __probe_ip field that the kernel adds to all dynamic
+	 * probe formats.
+	 */
+	PROBE__FTRACE	= 4,
+};
+
+static void evsel__resolve_probe_type(struct evsel *evsel)
+{
+	const char *name = evsel__pmu_name(evsel);
+
+	if (!strcmp(name, "kprobe"))
+		evsel->probe_type = PROBE__KPROBE;
+	else if (!strcmp(name, "uprobe"))
+		evsel->probe_type = PROBE__UPROBE;
+	else if (!strcmp(name, "tracepoint") && evsel__field(evsel, "__probe_ip"))
+		evsel->probe_type = PROBE__FTRACE;
+	else
+		evsel->probe_type = PROBE__NOPE;
+}
+
+bool evsel__is_probe(struct evsel *evsel)
+{
+	if (evsel->probe_type == PROBE__UNKNOWN)
+		evsel__resolve_probe_type(evsel);
+
+	return evsel->probe_type > PROBE__NOPE;
+}
+
+bool evsel__is_kprobe(struct evsel *evsel)
+{
+	if (evsel->probe_type == PROBE__UNKNOWN)
+		evsel__resolve_probe_type(evsel);
+
+	return evsel->probe_type == PROBE__KPROBE;
+}
+
+bool evsel__is_uprobe(struct evsel *evsel)
+{
+	if (evsel->probe_type == PROBE__UNKNOWN)
+		evsel__resolve_probe_type(evsel);
+
+	return evsel->probe_type == PROBE__UPROBE;
+}
+
 #define FD(e, x, y) (*(int *)xyarray__entry(e->core.fd, x, y))
 
 int __evsel__sample_size(u64 sample_type)
@@ -413,6 +465,7 @@ void evsel__init(struct evsel *evsel,
 	evsel->supported     = true;
 	evsel->alternate_hw_config = PERF_COUNT_HW_MAX;
 	evsel->script_output_type = -1; // FIXME: OUTPUT_TYPE_UNSET, see builtin-script.c
+	evsel->probe_type = PROBE__UNKNOWN;
 }
 
 struct evsel *evsel__new_idx(struct perf_event_attr *attr, int idx)
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 8009be22cc3f1055..163fc2b6a7eacca4 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -126,6 +126,7 @@ struct evsel {
 	bool			needs_uniquify;
 	bool			fallenback_eacces;
 	bool			fallenback_eopnotsupp;
+	u8			probe_type:3;
 	struct hashmap		*per_pkg_mask;
 	int			err;
 	int			script_output_type;
@@ -259,6 +260,10 @@ struct perf_pmu *evsel__find_pmu(const struct evsel *evsel);
 const char *evsel__pmu_name(const struct evsel *evsel);
 bool evsel__is_aux_event(const struct evsel *evsel);
 
+bool evsel__is_probe(struct evsel *evsel);
+bool evsel__is_kprobe(struct evsel *evsel);
+bool evsel__is_uprobe(struct evsel *evsel);
+
 struct evsel *evsel__new_idx(struct perf_event_attr *attr, int idx);
 
 static inline struct evsel *evsel__new(struct perf_event_attr *attr)
@@ -397,8 +402,22 @@ struct tep_format_field;
 
 u64 format_field__intval(struct tep_format_field *field, struct perf_sample *sample, bool needs_swap);
 
+#ifdef HAVE_LIBTRACEEVENT
 struct tep_format_field *evsel__field(struct evsel *evsel, const char *name);
 struct tep_format_field *evsel__common_field(struct evsel *evsel, const char *name);
+#else
+static inline struct tep_format_field *
+evsel__field(struct evsel *evsel __maybe_unused, const char *name __maybe_unused)
+{
+	return NULL;
+}
+
+static inline struct tep_format_field *
+evsel__common_field(struct evsel *evsel __maybe_unused, const char *name __maybe_unused)
+{
+	return NULL;
+}
+#endif
 
 bool __evsel__match(const struct evsel *evsel, u32 type, u64 config);
 
-- 
2.54.0