perf intel-pt: Track sideband system-wide when needed

User space tasks can migrate between CPUs, so when tracing selected CPUs,
sideband for all CPUs is still needed. This is in preparation for allowing
system-wide events on all CPUs while the user requested events are on only
user requested CPUs.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Link: https://lore.kernel.org/r/20220524075436.29144-9-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/arch/x86/util/intel-pt.c b/tools/perf/arch/x86/util/intel-pt.c
index 0ee93894a0daded7a4d11fb2d27d755545f24635..06c2cdfd8f2fa7d5053021cf89a6ed9a56adb611 100644 (file)
--- a/tools/perf/arch/x86/util/intel-pt.c
+++ b/tools/perf/arch/x86/util/intel-pt.c
@@ -864,20 +864,22 @@ static int intel_pt_recording_options(struct auxtrace_record *itr,
 
        /* Add dummy event to keep tracking */
        if (opts->full_auxtrace) {
+               bool need_system_wide_tracking;
                struct evsel *tracking_evsel;
 
-               err = parse_events(evlist, "dummy:u", NULL);
-               if (err)
-                       return err;
+               /*
+                * User space tasks can migrate between CPUs, so when tracing
+                * selected CPUs, sideband for all CPUs is still needed.
+                */
+               need_system_wide_tracking = evlist->core.has_user_cpus &&
+                                           !intel_pt_evsel->core.attr.exclude_user;
 
-               tracking_evsel = evlist__last(evlist);
+               tracking_evsel = evlist__add_aux_dummy(evlist, need_system_wide_tracking);
+               if (!tracking_evsel)
+                       return -ENOMEM;
 
                evlist__set_tracking_event(evlist, tracking_evsel);
 
-               tracking_evsel->core.attr.freq = 0;
-               tracking_evsel->core.attr.sample_period = 1;
-
-               tracking_evsel->no_aux_samples = true;
                if (need_immediate)
                        tracking_evsel->immediate = true;