perf cs-etm: Add fix for coresight trace for any range of CPUs

The current implementation supports coresight trace decode for a range
of CPUs, if the first CPU is CPU0.

Perf report segfaults, if tried for sparse CPUs list and also for
any range of CPUs(non zero first CPU).

Adding a fix to perf report for any range of CPUs and for sparse list.

Signed-off-by: Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>
Link: https://lore.kernel.org/r/20230421055253.83912-1-gankulkarni@os.amperecomputing.com
Cc: suzuki.poulose@arm.com
Cc: acme@kernel.org
Cc: mathieu.poirier@linaro.org
Cc: mike.leach@linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: darren@os.amperecomputing.com
Cc: scclevenger@os.amperecomputing.com
Cc: scott@os.amperecomputing.com
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/cs-etm.c

@@ -290,6 +290,25 @@ static int cs_etm__metadata_set_trace_id(u8 trace_chan_id, u64 *cpu_metadata)
 		(typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask)); \
 	})
 
+/*
+ * Get a metadata for a specific cpu from an array.
+ *
+ */
+static u64 *get_cpu_data(struct cs_etm_auxtrace *etm, int cpu)
+{
+	int i;
+	u64 *metadata = NULL;
+
+	for (i = 0; i < etm->num_cpu; i++) {
+		if (etm->metadata[i][CS_ETM_CPU] == (u64)cpu) {
+			metadata = etm->metadata[i];
+			break;
+		}
+	}
+
+	return metadata;
+}
+
 /*
  * Handle the PERF_RECORD_AUX_OUTPUT_HW_ID event.
  *
@@ -359,8 +378,11 @@ static int cs_etm__process_aux_output_hw_id(struct perf_session *session,
 		return 0;
 	}
 
+	cpu_data = get_cpu_data(etm, cpu);
+	if (cpu_data == NULL)
+		return err;
+
 	/* not one we've seen before - lets map it */
-	cpu_data = etm->metadata[cpu];
 	err = cs_etm__map_trace_id(trace_chan_id, cpu_data);
 	if (err)
 		return err;