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Message-Id: <20220615130901.1151397-2-german.gomez@arm.com>
Date: Wed, 15 Jun 2022 14:09:01 +0100
From: German Gomez <german.gomez@....com>
To: linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
acme@...nel.org
Cc: German Gomez <german.gomez@....com>,
Anshuman Khandual <anshuman.khandual@....com>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>
Subject: [PATCH] perf test: Add test for branch stack sampling
Add a self test for branch stack sampling, to check that we get the
expected branch types, and filters behave as expected.
Suggested-by: Anshuman Khandual <anshuman.khandual@....com>
Signed-off-by: German Gomez <german.gomez@....com>
---
tools/perf/tests/shell/lib/brstack/main.h | 16 +++++
tools/perf/tests/shell/lib/brstack/test.c | 24 +++++++
tools/perf/tests/shell/test_brstack.sh | 86 +++++++++++++++++++++++
3 files changed, 126 insertions(+)
create mode 100644 tools/perf/tests/shell/lib/brstack/main.h
create mode 100644 tools/perf/tests/shell/lib/brstack/test.c
create mode 100755 tools/perf/tests/shell/test_brstack.sh
diff --git a/tools/perf/tests/shell/lib/brstack/main.h b/tools/perf/tests/shell/lib/brstack/main.h
new file mode 100644
index 000000000..94d2665ec
--- /dev/null
+++ b/tools/perf/tests/shell/lib/brstack/main.h
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+#define BENCH_RUNS 99999
+
+void bench(void);
+
+int main(void)
+{
+ int cnt = 0;
+
+ while (1) {
+ if ((cnt++) > BENCH_RUNS)
+ break;
+ bench(); /* call */
+ } /* branch (uncond) */
+ return 0;
+}
diff --git a/tools/perf/tests/shell/lib/brstack/test.c b/tools/perf/tests/shell/lib/brstack/test.c
new file mode 100644
index 000000000..8a2308901
--- /dev/null
+++ b/tools/perf/tests/shell/lib/brstack/test.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "main.h"
+
+int cnt;
+
+void bar(void)
+{
+} /* return */
+
+void foo(void)
+{
+ bar(); /* call */
+} /* return */
+
+void bench(void)
+{
+ void (*foo_ind)(void) = foo;
+
+ if ((cnt++) % 3) /* branch (cond) */
+ foo(); /* call */
+
+ bar(); /* call */
+ foo_ind(); /* call (ind) */
+}
diff --git a/tools/perf/tests/shell/test_brstack.sh b/tools/perf/tests/shell/test_brstack.sh
new file mode 100755
index 000000000..2b1a1b20a
--- /dev/null
+++ b/tools/perf/tests/shell/test_brstack.sh
@@ -0,0 +1,86 @@
+#!/bin/sh
+# Check branch stack sampling
+
+# SPDX-License-Identifier: GPL-2.0
+# German Gomez <german.gomez@....com>, 2022
+
+set -e
+
+# we need a C compiler to build the test programs
+# so bail if none is found
+if ! [ -x "$(command -v cc)" ]; then
+ echo "failed: no compiler, install gcc"
+ exit 2
+fi
+
+# skip the test if the hardware doesn't support branch stack sampling
+perf record -b -o- -- true > /dev/null || exit 2
+
+TMPDIR=$(mktemp -d /tmp/__perf_test.program.XXXXX)
+
+cleanup() {
+ rm -rf $TMPDIR
+}
+
+trap cleanup exit term int
+
+test_user_branches() {
+ echo
+ echo "Testing user branch stack sampling"
+ echo
+
+ cc -fno-inline -g "$(dirname $0)/lib/brstack/test.c" -o $TMPDIR/a.out
+
+ perf record -o $TMPDIR/perf.data -q --branch-filter any,save_type,u -- $TMPDIR/a.out
+ perf script -i $TMPDIR/perf.data --fields brstacksym | xargs -n1 > $TMPDIR/perf.script
+
+ # example of branch entries:
+ # foo+0x14/bar+0x40/P/-/-/0/CALL
+
+ set -x
+ egrep -m1 "^bench\+[^ ]*/foo\+[^ ]*/IND_CALL$" $TMPDIR/perf.script
+ egrep -m1 "^foo\+[^ ]*/bar\+[^ ]*/CALL$" $TMPDIR/perf.script
+ egrep -m1 "^bench\+[^ ]*/foo\+[^ ]*/CALL$" $TMPDIR/perf.script
+ egrep -m1 "^bench\+[^ ]*/bar\+[^ ]*/CALL$" $TMPDIR/perf.script
+ egrep -m1 "^bar\+[^ ]*/foo\+[^ ]*/RET$" $TMPDIR/perf.script
+ egrep -m1 "^foo\+[^ ]*/bench\+[^ ]*/RET$" $TMPDIR/perf.script
+ egrep -m1 "^bench\+[^ ]*/bench\+[^ ]*/COND$" $TMPDIR/perf.script
+ egrep -m1 "^main\+[^ ]*/main\+[^ ]*/UNCOND$" $TMPDIR/perf.script
+ set +x
+
+ # some branch types are still not being tested:
+ # IND COND_CALL COND_RET SYSCALL SYSRET IRQ SERROR NO_TX
+}
+
+test_filter() {
+ local filter=$1
+ local expect=$2
+
+ echo
+ echo "Testing branch stack filtering permutation ($filter,$expect)"
+ echo
+
+ cc -fno-inline -g "$(dirname $0)/lib/brstack/test.c" -o $TMPDIR/a.out
+
+ perf record -o $TMPDIR/perf.data -q --branch-filter $filter,save_type,u -- $TMPDIR/a.out
+ perf script -i $TMPDIR/perf.data --fields brstack | xargs -n1 > $TMPDIR/perf.script
+
+ # fail if we find any branch type that doesn't match any of the expected ones
+ # also consider UNKNOWN branch types (-)
+ if egrep -vm1 "^[^ ]*/($expect|-|( *))$" $TMPDIR/perf.script; then
+ return 1
+ fi
+}
+
+test_user_branches
+
+# first argument <arg0> is the argument passed to "--branch-stack <arg0>,save_type,u"
+# second argument are the expected branch types for the given filter
+test_filter "any_call" "CALL|IND_CALL|COND_CALL|SYSCALL|IRQ|FAULT_DATA|FAULT_INST"
+test_filter "call" "CALL|SYSCALL"
+test_filter "cond" "COND"
+test_filter "any_ret" "RET|COND_RET|SYSRET|ERET"
+
+test_filter "call,cond" "CALL|SYSCALL|COND"
+test_filter "any_call,cond" "CALL|IND_CALL|COND_CALL|IRQ|FAULT_DATA|FAULT_INST|SYSCALL|COND"
+test_filter "cond,any_call,any_ret" "COND|CALL|IND_CALL|COND_CALL|SYSCALL|IRQ|FAULT_DATA|FAULT_INST|RET|COND_RET|SYSRET|ERET"
--
2.25.1
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