perf tools arm-spe: Don't allocate buffer or tracking event in discard mode

The buffer will never be written to so don't bother allocating it. The
tracking event is also not required.

Reviewed-by: Yeoreum Yun <[email protected]>
Signed-off-by: James Clark <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Athira Rajeev <[email protected]>
Cc: Graham Woodward <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: John Garry <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Leo Yan <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Michael Petlan <[email protected]>
Cc: Mike Leach <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Thomas Richter <[email protected]>
Cc: Veronika Molnarova <[email protected]>
Cc: Will Deacon <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: james-c-linaro

tools/perf/arch/arm64/util/arm-spe.c

@@ -376,7 +376,7 @@ static int arm_spe_recording_options(struct auxtrace_record *itr,
 			container_of(itr, struct arm_spe_recording, itr);
 	struct evsel *evsel, *tmp;
 	struct perf_cpu_map *cpus = evlist->core.user_requested_cpus;
-
+	bool discard = false;
 	int err;
 
 	sper->evlist = evlist;
@@ -396,10 +396,17 @@ static int arm_spe_recording_options(struct auxtrace_record *itr,
 		return 0;
 
 	evlist__for_each_entry_safe(evlist, tmp, evsel) {
-		if (evsel__is_aux_event(evsel))
+		if (evsel__is_aux_event(evsel)) {
 			arm_spe_setup_evsel(evsel, cpus);
+			if (evsel->core.attr.config &
+			    perf_pmu__format_bits(evsel->pmu, "discard"))
+				discard = true;
+		}
 	}
 
+	if (discard)
+		return 0;
+
 	err = arm_spe_setup_aux_buffer(opts);
 	if (err)
 		return err;