linux-kernel - [PATCH 02/12] perf tools: Support PERF_SAMPLE_BRANCH_HW

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Date:   Fri, 28 Feb 2020 08:30:01 -0800
From:   kan.liang@...ux.intel.com
To:     acme@...nel.org, jolsa@...hat.com, peterz@...radead.org,
        mingo@...hat.com, linux-kernel@...r.kernel.org
Cc:     namhyung@...nel.org, adrian.hunter@...el.com,
        mathieu.poirier@...aro.org, ravi.bangoria@...ux.ibm.com,
        alexey.budankov@...ux.intel.com, vitaly.slobodskoy@...el.com,
        pavel.gerasimov@...el.com, mpe@...erman.id.au, eranian@...gle.com,
        ak@...ux.intel.com, Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH 02/12] perf tools: Support PERF_SAMPLE_BRANCH_HW_INDEX

From: Kan Liang <kan.liang@...ux.intel.com>

A new branch sample type PERF_SAMPLE_BRANCH_HW_INDEX has been introduced
in latest kernel.

Enable HW_INDEX by default in LBR call stack mode.
If kernel doesn't support the sample type, switching it off.

Add HW_INDEX in attr_fprintf as well. User can check whether the branch
sample type is set via debug information or header.

Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
 tools/perf/util/evsel.c                   | 15 ++++++++++++---
 tools/perf/util/evsel.h                   |  1 +
 tools/perf/util/perf_event_attr_fprintf.c |  1 +
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 05883a45de5b..816d930d774e 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -712,7 +712,8 @@ static void __perf_evsel__config_callchain(struct evsel *evsel,
 				attr->branch_sample_type = PERF_SAMPLE_BRANCH_USER |
 							PERF_SAMPLE_BRANCH_CALL_STACK |
 							PERF_SAMPLE_BRANCH_NO_CYCLES |
-							PERF_SAMPLE_BRANCH_NO_FLAGS;
+							PERF_SAMPLE_BRANCH_NO_FLAGS |
+							PERF_SAMPLE_BRANCH_HW_INDEX;
 			}
 		} else
 			 pr_warning("Cannot use LBR callstack with branch stack. "
@@ -763,7 +764,8 @@ perf_evsel__reset_callgraph(struct evsel *evsel,
 	if (param->record_mode == CALLCHAIN_LBR) {
 		perf_evsel__reset_sample_bit(evsel, BRANCH_STACK);
 		attr->branch_sample_type &= ~(PERF_SAMPLE_BRANCH_USER |
-					      PERF_SAMPLE_BRANCH_CALL_STACK);
+					      PERF_SAMPLE_BRANCH_CALL_STACK |
+					      PERF_SAMPLE_BRANCH_HW_INDEX);
 	}
 	if (param->record_mode == CALLCHAIN_DWARF) {
 		perf_evsel__reset_sample_bit(evsel, REGS_USER);
@@ -1673,6 +1675,8 @@ static int evsel__open_cpu(struct evsel *evsel, struct perf_cpu_map *cpus,
 		evsel->core.attr.ksymbol = 0;
 	if (perf_missing_features.bpf)
 		evsel->core.attr.bpf_event = 0;
+	if (perf_missing_features.branch_hw_idx)
+		evsel->core.attr.branch_sample_type &= ~PERF_SAMPLE_BRANCH_HW_INDEX;
 retry_sample_id:
 	if (perf_missing_features.sample_id_all)
 		evsel->core.attr.sample_id_all = 0;
@@ -1784,7 +1788,12 @@ static int evsel__open_cpu(struct evsel *evsel, struct perf_cpu_map *cpus,
 	 * Must probe features in the order they were added to the
 	 * perf_event_attr interface.
 	 */
-	if (!perf_missing_features.aux_output && evsel->core.attr.aux_output) {
+	if (!perf_missing_features.branch_hw_idx &&
+	    (evsel->core.attr.branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX)) {
+		perf_missing_features.branch_hw_idx = true;
+		pr_debug2("switching off branch HW index support\n");
+		goto fallback_missing_features;
+	} else if (!perf_missing_features.aux_output && evsel->core.attr.aux_output) {
 		perf_missing_features.aux_output = true;
 		pr_debug2_peo("Kernel has no attr.aux_output support, bailing out\n");
 		goto out_close;
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 99a0cb60c556..33804740e2ca 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -119,6 +119,7 @@ struct perf_missing_features {
 	bool ksymbol;
 	bool bpf;
 	bool aux_output;
+	bool branch_hw_idx;
 };
 
 extern struct perf_missing_features perf_missing_features;
diff --git a/tools/perf/util/perf_event_attr_fprintf.c b/tools/perf/util/perf_event_attr_fprintf.c
index 651203126c71..355d3458d4e6 100644
--- a/tools/perf/util/perf_event_attr_fprintf.c
+++ b/tools/perf/util/perf_event_attr_fprintf.c
@@ -50,6 +50,7 @@ static void __p_branch_sample_type(char *buf, size_t size, u64 value)
 		bit_name(ABORT_TX), bit_name(IN_TX), bit_name(NO_TX),
 		bit_name(COND), bit_name(CALL_STACK), bit_name(IND_JUMP),
 		bit_name(CALL), bit_name(NO_FLAGS), bit_name(NO_CYCLES),
+		bit_name(HW_INDEX),
 		{ .name = NULL, }
 	};
 #undef bit_name
-- 
2.17.1