perf intel-pt: Use itrace error flags to suppress some errors

The itrace "e" option may be followed by flags which affect what errors
will or will not be reported.  Each flag must be preceded by either '+' or '-'.
The flags supported by Intel PT are:

		-o	Suppress overflow errors
		-l	Suppress trace data lost errors
For example, for errors but not overflow or data lost errors:

	--itrace=e-o-l

Suppressing those errors can be useful for testing and debugging because
they are not due to decoding.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200710151104.15137-7-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-intel-pt.txt

@@ -871,7 +871,14 @@ Developer Manuals.
 
 Error events show where the decoder lost the trace.  Error events
 are quite important.  Users must know if what they are seeing is a complete
-picture or not.
+picture or not. The "e" option may be followed by flags which affect what errors
+will or will not be reported.  Each flag must be preceded by either '+' or '-'.
+The flags supported by Intel PT are:
+		-o	Suppress overflow errors
+		-l	Suppress trace data lost errors
+For example, for errors but not overflow or data lost errors:
+
+	--itrace=e-o-l
 
 The "d" option will cause the creation of a file "intel_pt.log" containing all
 decoded packets and instructions.  Note that this option slows down the decoder

tools/perf/util/intel-pt.c

@@ -1863,6 +1863,15 @@ static int intel_pt_synth_error(struct intel_pt *pt, int code, int cpu,
 	char msg[MAX_AUXTRACE_ERROR_MSG];
 	int err;
 
+	if (pt->synth_opts.error_minus_flags) {
+		if (code == INTEL_PT_ERR_OVR &&
+		    pt->synth_opts.error_minus_flags & AUXTRACE_ERR_FLG_OVERFLOW)
+			return 0;
+		if (code == INTEL_PT_ERR_LOST &&
+		    pt->synth_opts.error_minus_flags & AUXTRACE_ERR_FLG_DATA_LOST)
+			return 0;
+	}
+
 	intel_pt__strerror(code, msg, MAX_AUXTRACE_ERROR_MSG);
 
 	auxtrace_synth_error(&event.auxtrace_error, PERF_AUXTRACE_ERROR_ITRACE,