perf cs-etm: Validate timestamp tracing in per-thread mode

So far, it's impossible to validate timestamp trace in Arm CoreSight when
the perf is in the per-thread mode.  E.g. for the command:

  perf record -e cs_etm/timestamp/ --per-thread -- ls

The command enables config 'timestamp' for 'cs_etm' event in the
per-thread mode.  In this case, the function cs_etm_validate_config()
directly bails out and skips validation.

Given profiled process can be scheduled on any CPUs in the per-thread
mode, this patch validates timestamp tracing for all CPUs when detect
the CPU map is empty.
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: James Clark <james.clark@arm.com>
Acked-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: coresight@lists.linaro.org
Link: https://lore.kernel.org/r/20231014074159.1667880-2-leo.yan@linaro.orgSigned-off-by: Namhyung Kim <namhyung@kernel.org>

tools/perf/arch/arm/util/cs-etm.c

@@ -205,8 +205,17 @@ static int cs_etm_validate_config(struct auxtrace_record *itr,
 	for (i = 0; i < cpu__max_cpu().cpu; i++) {
 		struct perf_cpu cpu = { .cpu = i, };
 
-		if (!perf_cpu_map__has(event_cpus, cpu) ||
-		    !perf_cpu_map__has(online_cpus, cpu))
+		/*
+		 * In per-cpu case, do the validation for CPUs to work with.
+		 * In per-thread case, the CPU map is empty.  Since the traced
+		 * program can run on any CPUs in this case, thus don't skip
+		 * validation.
+		 */
+		if (!perf_cpu_map__empty(event_cpus) &&
+		    !perf_cpu_map__has(event_cpus, cpu))
+			continue;
+
+		if (!perf_cpu_map__has(online_cpus, cpu))
 			continue;
 
 		err = cs_etm_validate_context_id(itr, evsel, i);