linux-kernel - [PATCH V3 6/6] perf intel-pt: Support itrace d+o option to direct debug log to stdout

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Date:   Wed, 27 Oct 2021 11:03:34 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...hat.com>, Andi Kleen <ak@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH V3 6/6] perf intel-pt: Support itrace d+o option to direct debug log to stdout

It can be useful to see debug output in between normal output.

Add support for AUXTRACE_LOG_FLG_USE_STDOUT to Intel PT.

Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
Reviewed-by: Andi Kleen <ak@...ux.intel.com>
---
 tools/perf/Documentation/perf-intel-pt.txt      | 1 +
 tools/perf/util/intel-pt-decoder/intel-pt-log.c | 8 ++++----
 tools/perf/util/intel-pt.c                      | 5 +++--
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/tools/perf/Documentation/perf-intel-pt.txt b/tools/perf/Documentation/perf-intel-pt.txt
index 5fa0a448e6a6..94933915e2f3 100644
--- a/tools/perf/Documentation/perf-intel-pt.txt
+++ b/tools/perf/Documentation/perf-intel-pt.txt
@@ -953,6 +953,7 @@ by flags which affect what debug messages will or will not be logged. Each flag
 must be preceded by either '+' or '-'. The flags support by Intel PT are:
 		-a	Suppress logging of perf events
 		+a	Log all perf events
+		+o	Output to stdout instead of "intel_pt.log"
 By default, logged perf events are filtered by any specified time ranges, but
 flag +a overrides that.
 
diff --git a/tools/perf/util/intel-pt-decoder/intel-pt-log.c b/tools/perf/util/intel-pt-decoder/intel-pt-log.c
index 09feb5b07d32..5f5dfc8753f3 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-log.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-log.c
@@ -82,10 +82,10 @@ static int intel_pt_log_open(void)
 	if (f)
 		return 0;
 
-	if (!log_name[0])
-		return -1;
-
-	f = fopen(log_name, "w+");
+	if (log_name[0])
+		f = fopen(log_name, "w+");
+	else
+		f = stdout;
 	if (!f) {
 		intel_pt_enable_logging = false;
 		return -1;
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 57e49b23ad25..793bac850268 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -3659,8 +3659,6 @@ int intel_pt_process_auxtrace_info(union perf_event *event,
 	if (err)
 		goto err_free;
 
-	intel_pt_log_set_name(INTEL_PT_PMU_NAME);
-
 	if (session->itrace_synth_opts->set) {
 		pt->synth_opts = *session->itrace_synth_opts;
 	} else {
@@ -3675,6 +3673,9 @@ int intel_pt_process_auxtrace_info(union perf_event *event,
 		pt->synth_opts.thread_stack = opts->thread_stack;
 	}
 
+	if (!(pt->synth_opts.log_plus_flags & AUXTRACE_LOG_FLG_USE_STDOUT))
+		intel_pt_log_set_name(INTEL_PT_PMU_NAME);
+
 	pt->session = session;
 	pt->machine = &session->machines.host; /* No kvm support */
 	pt->auxtrace_type = auxtrace_info->type;
-- 
2.25.1