perf stat,jevents: Introduce Default tags for the default mode

Introduce a new metricgroup, Default, to tag all the metric groups which
will be collected in the default mode.

Add a new field, DefaultMetricgroupName, in the JSON file to indicate
the real metric group name. It will be printed in the default output
to replace the event names.

There is nothing changed for the output format.

On SPR, both TopdownL1 and TopdownL2 are displayed in the default
output.

On ARM, Intel ICL and later platforms (before SPR), only TopdownL1 is
displayed in the default output.

Suggested-by: Stephane Eranian <[e-mail]>
Reviewed-by: Ian Rogers <[e-mail]>
Signed-off-by: Kan Liang <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Ahmad Yasin <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/builtin-stat.c

···
 		 * Add TopdownL1 metrics if they exist. To minimize
 		 * multiplexing, don't request threshold computation.
 		 */
-		if (metricgroup__has_metric(pmu, "TopdownL1")) {
+		if (metricgroup__has_metric(pmu, "Default")) {
 			struct evlist *metric_evlist = evlist__new();
 			struct evsel *metric_evsel;
 
 			if (!metric_evlist)
 				return -1;
 
-			if (metricgroup__parse_groups(metric_evlist, pmu, "TopdownL1",
+			if (metricgroup__parse_groups(metric_evlist, pmu, "Default",
 							/*metric_no_group=*/false,
 							/*metric_no_merge=*/false,
 							/*metric_no_threshold=*/true,

tools/perf/pmu-events/jevents.py

···
 # Attributes that are in pmu_metric rather than pmu_event.
 _json_metric_attributes = [
     'pmu', 'metric_name', 'metric_group', 'metric_expr', 'metric_threshold',
-    'desc', 'long_desc', 'unit', 'compat', 'metricgroup_no_group', 'aggr_mode',
-    'event_grouping'
+    'desc', 'long_desc', 'unit', 'compat', 'metricgroup_no_group',
+    'default_metricgroup_name', 'aggr_mode', 'event_grouping'
 ]
 # Attributes that are bools or enum int values, encoded as '0', '1',...
 _json_enum_attributes = ['aggr_mode', 'deprecated', 'event_grouping', 'perpkg']
···
     self.metric_name = jd.get('MetricName')
     self.metric_group = jd.get('MetricGroup')
     self.metricgroup_no_group = jd.get('MetricgroupNoGroup')
+    self.default_metricgroup_name = jd.get('DefaultMetricgroupName')
     self.event_grouping = convert_metric_constraint(jd.get('MetricConstraint'))
     self.metric_expr = None
     if 'MetricExpr' in jd:

tools/perf/pmu-events/pmu-events.h

···
 	const char *desc;
 	const char *long_desc;
 	const char *metricgroup_no_group;
+	const char *default_metricgroup_name;
 	enum aggr_mode_class aggr_mode;
 	enum metric_event_groups event_grouping;
 };

tools/perf/util/metricgroup.c

···
 	 * output.
 	 */
 	const char *metric_unit;
+	/**
+	 * Optional name of the metric group reported
+	 * if the Default metric group is being processed.
+	 */
+	const char *default_metricgroup_name;
 	/** Optional null terminated array of referenced metrics. */
 	struct metric_ref *metric_refs;
 	/**
···
 
 	m->pmu = pm->pmu ?: "cpu";
 	m->metric_name = pm->metric_name;
+	m->default_metricgroup_name = pm->default_metricgroup_name;
 	m->modifier = NULL;
 	if (modifier) {
 		m->modifier = strdup(modifier);