[PATCH v2 0/1] perf test: Add test for branch stack sampling

[PATCH v2 0/1] perf test: Add test for branch stack sampling

[German Gomez]

Hi,

While testing Anshuman Khandual's branch stack sampling ABI, and BRBE
driver ([1] and [2] respectively) I've been using this test to check the
consistency between arches (x86 and Arm64).

We will extend it with Arm64-specific tests once the BRBE driver has
been reviewed and merged, but for now I think this is generic enough to
also be useful for x86.

Thanks,
German

[1] https://lore.kernel.org/linux-arm-kernel/20220610035101.424112-1-anshuman.khandual@arm.com/
[2] https://lore.kernel.org/all/20220613100119.684673-1-anshuman.khandual@arm.com/

---

v2
  - (Ian Rogers) Include C test program in the shell script.
  - Drop references to Anshuman's ABI ext (FAULT_DATA and FAULT_INST).
    We will track and update this later if necessary.

German Gomez (1):
  perf test: Add test for branch stack sampling

 tools/perf/tests/shell/test_brstack.sh | 114 +++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100755 tools/perf/tests/shell/test_brstack.sh

-- 
2.25.1

[PATCH v2 1/1] perf test: Add test for branch stack sampling

[German Gomez]

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

Re: [PATCH v2 1/1] perf test: Add test for branch stack sampling

[Namhyung Kim]

Hello,

On Tue, Jul 5, 2022 at 8:05 AM German Gomez <german.gomez@arm.com> 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>

Acked-by: Namhyung Kim <namhyung@kernel.org>

Thanks,
Namhyung

Re: [PATCH v2 1/1] perf test: Add test for branch stack sampling

[German Gomez]

On 08/07/2022 21:31, Namhyung Kim wrote:
> Hello,
>
> On Tue, Jul 5, 2022 at 8:05 AM German Gomez <german.gomez@arm.com> 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>
> Acked-by: Namhyung Kim <namhyung@kernel.org>

Thanks a lot Namhyung!

>
> Thanks,
> Namhyung

Re: [PATCH v2 1/1] perf test: Add test for branch stack sampling

[Jiri Olsa]

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
> 

Re: [PATCH v2 1/1] perf test: Add test for branch stack sampling

[German Gomez]

On 11/07/2022 21:56, Jiri Olsa wrote:
> 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 a lot, Jiri!

>
> 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
>>

Re: [PATCH v2 1/1] perf test: Add test for branch stack sampling

[Arnaldo Carvalho de Melo]

Em Fri, Jul 08, 2022 at 01:31:43PM -0700, Namhyung Kim escreveu:
> Hello,
> 
> On Tue, Jul 5, 2022 at 8:05 AM German Gomez <german.gomez@arm.com> 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>
> 
> Acked-by: Namhyung Kim <namhyung@kernel.org>

Thanks, applied.

- Arnaldo