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Subject[PATCH v2 1/1] perf test: Add test for branch stack sampling
Date
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@arm.com>
Signed-off-by: German Gomez <german.gomez@arm.com>
---
tools/perf/tests/shell/test_brstack.sh | 114 +++++++++++++++++++++++++
1 file changed, 114 insertions(+)
create mode 100755 tools/perf/tests/shell/test_brstack.sh

diff --git a/tools/perf/tests/shell/test_brstack.sh b/tools/perf/tests/shell/test_brstack.sh
new file mode 100755
index 000000000..5f6f40a77
--- /dev/null
+++ b/tools/perf/tests/shell/test_brstack.sh
@@ -0,0 +1,114 @@
+#!/bin/sh
+# Check branch stack sampling
+
+# SPDX-License-Identifier: GPL-2.0
+# German Gomez <german.gomez@arm.com>, 2022
+
+# we need a C compiler to build the test programs
+# so bail if none is found
+if ! [ -x "$(command -v cc)" ]; then
+ echo "failed: no compiler, install gcc"
+ exit 2
+fi
+
+# skip the test if the hardware doesn't support branch stack sampling
+perf record -b -o- -e dummy -B true > /dev/null 2>&1 || exit 2
+
+TMPDIR=$(mktemp -d /tmp/__perf_test.program.XXXXX)
+
+cleanup() {
+ rm -rf $TMPDIR
+}
+
+trap cleanup exit term int
+
+gen_test_program() {
+ # generate test program
+ cat << EOF > $1
+#define BENCH_RUNS 999999
+int cnt;
+void bar(void) {
+} /* return */
+void foo(void) {
+ bar(); /* call */
+} /* return */
+void bench(void) {
+ void (*foo_ind)(void) = foo;
+ if ((cnt++) % 3) /* branch (cond) */
+ foo(); /* call */
+ bar(); /* call */
+ foo_ind(); /* call (ind) */
+}
+int main(void)
+{
+ int cnt = 0;
+ while (1) {
+ if ((cnt++) > BENCH_RUNS)
+ break;
+ bench(); /* call */
+ } /* branch (uncond) */
+ return 0;
+}
+EOF
+}
+
+test_user_branches() {
+ echo "Testing user branch stack sampling"
+
+ gen_test_program "$TEMPDIR/program.c"
+ cc -fno-inline -g "$TEMPDIR/program.c" -o $TMPDIR/a.out
+
+ perf record -o $TMPDIR/perf.data --branch-filter any,save_type,u -- $TMPDIR/a.out > /dev/null 2>&1
+ 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
+}
+
+# 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() {
+ local filter=$1
+ local expect=$2
+
+ echo "Testing branch stack filtering permutation ($filter,$expect)"
+
+ gen_test_program "$TEMPDIR/program.c"
+ cc -fno-inline -g "$TEMPDIR/program.c" -o $TMPDIR/a.out
+
+ perf record -o $TMPDIR/perf.data --branch-filter $filter,save_type,u -- $TMPDIR/a.out > /dev/null 2>&1
+ 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
+}
+
+set -e
+
+test_user_branches
+
+test_filter "any_call" "CALL|IND_CALL|COND_CALL|SYSCALL|IRQ"
+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|SYSCALL|COND"
+test_filter "cond,any_call,any_ret" "COND|CALL|IND_CALL|COND_CALL|SYSCALL|IRQ|RET|COND_RET|SYSRET|ERET"
--
2.25.1
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