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SubjectRe: [PATCH v2 1/1] perf test: Add test for branch stack sampling
On Tue, Jul 05, 2022 at 04:05:11PM +0100, German Gomez wrote:
> 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>

Tested-by: Jiri Olsa <jolsa@kernel.org>

thanks,
jirka

> ---
> 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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