linux-kernel - [PATCH v3 05/12] perf script: Add not taken event for branch stack

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Message-Id: <20250217195908.176207-6-leo.yan@arm.com>
Date: Mon, 17 Feb 2025 19:59:01 +0000
From: Leo Yan <leo.yan@....com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	James Clark <james.clark@...aro.org>,
	Mike Leach <mike.leach@...aro.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	Will Deacon <will@...nel.org>,
	Graham Woodward <graham.woodward@....com>,
	Paschalis.Mpeis@....com,
	linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Cc: Leo Yan <leo.yan@....com>
Subject: [PATCH v3 05/12] perf script: Add not taken event for branch stack

The branch stack has an existed field for printing mispredict, extend
the field for printing events and add support not-taken event.

Reviewed-by: Ian Rogers <irogers@...gle.com>
Reviewed-by: James Clark <james.clark@...aro.org>
Signed-off-by: Leo Yan <leo.yan@....com>
---
 tools/perf/builtin-script.c | 20 +++++++++++++-------
 tools/perf/util/branch.h    |  3 ++-
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 2c4b1fb7dc72..43bf327bb72b 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -935,19 +935,25 @@ static int perf_sample__fprintf_start(struct perf_script *script,
 	return printed;
 }
 
-static inline char
-mispred_str(struct branch_entry *br)
+static inline size_t
+bstack_event_str(struct branch_entry *br, char *buf, size_t sz)
 {
-	if (!(br->flags.mispred  || br->flags.predicted))
-		return '-';
+	if (!(br->flags.mispred || br->flags.predicted || br->flags.not_taken))
+		return snprintf(buf, sz, "-");
 
-	return br->flags.predicted ? 'P' : 'M';
+	return snprintf(buf, sz, "%s%s",
+			br->flags.predicted ? "P" : "M",
+			br->flags.not_taken ? "N" : "");
 }
 
 static int print_bstack_flags(FILE *fp, struct branch_entry *br)
 {
-	return fprintf(fp, "/%c/%c/%c/%d/%s/%s ",
-		       mispred_str(br),
+	char events[16] = { 0 };
+	size_t pos;
+
+	pos = bstack_event_str(br, events, sizeof(events));
+	return fprintf(fp, "/%s/%c/%c/%d/%s/%s ",
+		       pos < 0 ? "-" : events,
 		       br->flags.in_tx ? 'X' : '-',
 		       br->flags.abort ? 'A' : '-',
 		       br->flags.cycles,
diff --git a/tools/perf/util/branch.h b/tools/perf/util/branch.h
index b80c12c74bbb..7429530fa774 100644
--- a/tools/perf/util/branch.h
+++ b/tools/perf/util/branch.h
@@ -25,7 +25,8 @@ struct branch_flags {
 			u64 spec:2;
 			u64 new_type:4;
 			u64 priv:3;
-			u64 reserved:31;
+			u64 not_taken:1;
+			u64 reserved:30;
 		};
 	};
 };
-- 
2.34.1