perf parse-events: Fix missing slots for Intel topdown metric events

Topdown metric events require grouping with a slots event. In perf
metrics this is currently achieved by metrics adding an unnecessary
"0 * tma_info_thread_slots". New TMA metrics trigger optimizations of
the metric expression that removes the event and breaks the metric due
to the missing but required event. Add a pass immediately before
sorting and fixing parsed events, that insert a slots event if one is
missing. Update test expectations to match this.

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250719030517.1990983-15-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

3 files changed, 54 insertions, 0 deletions

diff --git a/tools/perf/arch/x86/util/evlist.c b/tools/perf/arch/x86/util/evlist.c
index 1969758cc8c1..75e9d00a1494 100644
--- a/tools/perf/arch/x86/util/evlist.c
+++ b/tools/perf/arch/x86/util/evlist.c
@@ -81,3 +81,27 @@ int arch_evlist__cmp(const struct evsel *lhs, const struct evsel *rhs)
 	/* Default ordering by insertion index. */
 	return lhs->core.idx - rhs->core.idx;
 }
+
+int arch_evlist__add_required_events(struct list_head *list)
+{
+	struct evsel *pos, *metric_event = NULL;
+	int idx = 0;
+
+	if (!topdown_sys_has_perf_metrics())
+		return 0;
+
+	list_for_each_entry(pos, list, core.node) {
+		if (arch_is_topdown_slots(pos)) {
+			/* Slots event already present, nothing to do. */
+			return 0;
+		}
+		if (metric_event == NULL && arch_is_topdown_metrics(pos))
+			metric_event = pos;
+		idx++;
+	}
+	if (metric_event == NULL) {
+		/* No topdown metric events, nothing to do. */
+		return 0;
+	}
+	return topdown_insert_slots_event(list, idx + 1, metric_event);
+}
diff --git a/tools/perf/arch/x86/util/topdown.c b/tools/perf/arch/x86/util/topdown.c
index 66b231fbf52e..0d01b662627a 100644
--- a/tools/perf/arch/x86/util/topdown.c
+++ b/tools/perf/arch/x86/util/topdown.c
@@ -77,3 +77,31 @@ bool arch_topdown_sample_read(struct evsel *leader)
 
 	return false;
 }
+
+/*
+ * Make a copy of the topdown metric event metric_event with the given index but
+ * change its configuration to be a topdown slots event. Copying from
+ * metric_event ensures modifiers are the same.
+ */
+int topdown_insert_slots_event(struct list_head *list, int idx, struct evsel *metric_event)
+{
+	struct evsel *evsel = evsel__new_idx(&metric_event->core.attr, idx);
+
+	if (!evsel)
+		return -ENOMEM;
+
+	evsel->core.attr.config = TOPDOWN_SLOTS;
+	evsel->core.cpus = perf_cpu_map__get(metric_event->core.cpus);
+	evsel->core.pmu_cpus = perf_cpu_map__get(metric_event->core.pmu_cpus);
+	evsel->core.is_pmu_core = true;
+	evsel->pmu = metric_event->pmu;
+	evsel->name = strdup("slots");
+	evsel->precise_max = metric_event->precise_max;
+	evsel->sample_read = metric_event->sample_read;
+	evsel->weak_group = metric_event->weak_group;
+	evsel->bpf_counter = metric_event->bpf_counter;
+	evsel->retire_lat = metric_event->retire_lat;
+	evsel__set_leader(evsel, evsel__leader(metric_event));
+	list_add_tail(&evsel->core.node, list);
+	return 0;
+}
diff --git a/tools/perf/arch/x86/util/topdown.h b/tools/perf/arch/x86/util/topdown.h
index 2349536cf882..69035565e649 100644
--- a/tools/perf/arch/x86/util/topdown.h
+++ b/tools/perf/arch/x86/util/topdown.h
@@ -5,9 +5,11 @@
 #include <stdbool.h>
 
 struct evsel;
+struct list_head;
 
 bool topdown_sys_has_perf_metrics(void);
 bool arch_is_topdown_slots(const struct evsel *evsel);
 bool arch_is_topdown_metrics(const struct evsel *evsel);
+int topdown_insert_slots_event(struct list_head *list, int idx, struct evsel *metric_event);
 
 #endif