perf evsel: Modify group pmu name for software events

If we have a group of {cycles,faults} then we need the faults software
event to appear to be on the same PMU as cycles so that we don't split
the group in parse_events__sort_events_and_fix_groups.

This case is relatively easy as cycles is the leader and will have a PMU
name. In the reverse case, {faults,cycles} we still need faults to
appear to have the PMU name of cycles but the old behavior is just to
return "cpu".

For hybrid this fails as cycles will be on "cpu_core" or "cpu_atom",
causing faults to be split into a different group.

Change the behavior for software events so that the whole group is
searched for the named PMU.

Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ahmad Yasin <ahmad.yasin@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Caleb Biggers <caleb.biggers@intel.com>
Cc: Edward Baker <edward.baker@intel.com>
Cc: Florian Fischer <florian.fischer@muhq.space>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kang Minchul <tegongkang@gmail.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Perry Taylor <perry.taylor@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Samantha Alt <samantha.alt@intel.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Weilin Wang <weilin.wang@intel.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Link: https://lore.kernel.org/r/20230502223851.2234828-20-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Author: captain5050

tools/perf/util/evsel.c

@@ -829,23 +829,26 @@ bool evsel__name_is(struct evsel *evsel, const char *name)
 
 const char *evsel__group_pmu_name(const struct evsel *evsel)
 {
-	const struct evsel *leader;
+	struct evsel *leader, *pos;
 
 	/* If the pmu_name is set use it. pmu_name isn't set for CPU and software events. */
 	if (evsel->pmu_name)
 		return evsel->pmu_name;
 	/*
 	 * Software events may be in a group with other uncore PMU events. Use
-	 * the pmu_name of the group leader to avoid breaking the software event
-	 * out of the group.
+	 * the pmu_name of the first non-software event to avoid breaking the
+	 * software event out of the group.
 	 *
 	 * Aux event leaders, like intel_pt, expect a group with events from
 	 * other PMUs, so substitute the AUX event's PMU in this case.
 	 */
 	leader  = evsel__leader(evsel);
-	if ((evsel->core.attr.type == PERF_TYPE_SOFTWARE || evsel__is_aux_event(leader)) &&
-	    leader->pmu_name) {
-		return leader->pmu_name;
+	if (evsel->core.attr.type == PERF_TYPE_SOFTWARE || evsel__is_aux_event(leader)) {
+		/* Starting with the leader, find the first event with a named PMU. */
+		for_each_group_evsel(pos, leader) {
+			if (pos->pmu_name)
+				return pos->pmu_name;
+		}
 	}
 
 	return "cpu";