linux-kernel - [PATCH] perf tools: set no branch type for dummy event in PT

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Date:   Wed, 28 Jun 2017 10:31:53 -0400
From:   kan.liang@...el.com
To:     acme@...nel.org, linux-kernel@...r.kernel.org
Cc:     mingo@...hat.com, peterz@...radead.org, jolsa@...hat.com,
        adrian.hunter@...el.com, alexander.shishkin@...ux.intel.com,
        ak@...ux.intel.com, Kan Liang <kan.liang@...el.com>
Subject: [PATCH] perf tools: set no branch type for dummy event in PT

From: Kan Liang <kan.liang@...el.com>

An earlier kernel patch allowed enabling PT and LBR at the same
time on Goldmont. 
commit ccbebba4c6bf ("perf/x86/intel/pt: Bypass PT vs. LBR
exclusivity if the core supports it")
However, users still cannot use Intel PT and LBRs simultaneously.
    $ sudo perf record -e cycles,intel_pt//u -b  -- sleep 1
    Error:
    PMU Hardware doesn't support sampling/overflow-interrupts.

PT implicitly adds dummy event in perf tool. dummy event is
software event which doesn't support LBR.

Always setting branch_type=no for dummy event in Intel PT.

Signed-off-by: Kan Liang <kan.liang@...el.com>
---
 tools/perf/arch/x86/util/intel-pt.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/tools/perf/arch/x86/util/intel-pt.c b/tools/perf/arch/x86/util/intel-pt.c
index f630de0..651ab9e 100644
--- a/tools/perf/arch/x86/util/intel-pt.c
+++ b/tools/perf/arch/x86/util/intel-pt.c
@@ -544,6 +544,22 @@ static int intel_pt_validate_config(struct perf_pmu *intel_pt_pmu,
 					evsel->attr.config);
 }
 
+static int add_no_lbr_config_term(struct list_head *config_terms)
+{
+	struct perf_evsel_config_term *lbr_term;
+
+	lbr_term = zalloc(sizeof(*lbr_term));
+	if (!lbr_term)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&lbr_term->list);
+	lbr_term->type = PERF_EVSEL__CONFIG_TERM_BRANCH;
+	lbr_term->val.branch = strdup("no");
+	list_add_tail(&lbr_term->list, config_terms);
+
+	return 0;
+}
+
 static int intel_pt_recording_options(struct auxtrace_record *itr,
 				      struct perf_evlist *evlist,
 				      struct record_opts *opts)
@@ -701,6 +717,8 @@ static int intel_pt_recording_options(struct auxtrace_record *itr,
 				perf_evsel__set_sample_bit(switch_evsel, TIME);
 				perf_evsel__set_sample_bit(switch_evsel, CPU);
 
+				add_no_lbr_config_term(&switch_evsel->config_terms);
+
 				opts->record_switch_events = false;
 				ptr->have_sched_switch = 3;
 			} else {
@@ -760,6 +778,7 @@ static int intel_pt_recording_options(struct auxtrace_record *itr,
 			/* And the CPU for switch events */
 			perf_evsel__set_sample_bit(tracking_evsel, CPU);
 		}
+		add_no_lbr_config_term(&tracking_evsel->config_terms);
 	}
 
 	/*
-- 
2.9.4