linux-kernel - [BUG] perf: intel_pt won't display kernel function

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Date:   Wed, 3 Apr 2019 16:37:38 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Andi Kleen <andi@...stfloor.org>, acme@...nel.org,
        jolsa@...nel.org, namhyung@...nel.org,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Andi Kleen <ak@...ux.intel.com>,
        Song Liu <songliubraving@...com>
Subject: [BUG] perf: intel_pt won't display kernel function

hi,
perf script --call-trace stop working for me recently,
and displays only user space functions

I bisected that to:
  7b612e291a5a perf tools: Synthesize PERF_RECORD_* for loaded BPF programs

data from following comands will display user space functions only:
  # perf-with-kcore record pt -e intel_pt// -- ls
  # perf-with-kcore script pt --call-trace

when I disable the bpf synthesizing (patch below), kernel functions are back

I guess the new events mess up with intel_pt decoder somehow


thanks,
jirka


---
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 4e2d953d4bc5..3daa78bc6549 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1114,10 +1114,12 @@ static int record__synthesize(struct record *rec, bool tail)
 		return err;
 	}
 
+#if 0
 	err = perf_event__synthesize_bpf_events(session, process_synthesized_event,
 						machine, opts);
 	if (err < 0)
 		pr_warning("Couldn't synthesize bpf events.\n");
+#endif
 
 	err = __machine__synthesize_threads(machine, tool, &opts->target, rec->evlist->threads,
 					    process_synthesized_event, opts->sample_address,