From 2ac05f8f2e4b9068e5bbc0836b35abafd70f02c1 Mon Sep 17 00:00:00 2001 From: Athira Rajeev Date: Fri, 10 Jun 2022 19:10:48 +0530 Subject: selftests/powerpc/pmu: Add selftest to check branch stack enablement will not crash on any platforms While enabling branch stack for an event, BHRB (Branch History Rolling Buffer) filter is set using bhrb_filter_map() callback. This callback is not defined for cases like generic_compat_pmu or in case where there is no PMU registered. A fix was added in kernel to address a crash issue observed while enabling branch stack for environments which doesn't have this callback. commit b460b512417a ("powerpc/perf: Fix crashes with generic_compat_pmu & BHRB"). Add perf sampling test to exercise this code path and make sure enabling branch stack shouldn't crash in any platform. Testcase uses software event cycles since software event is available and can be used even in cases without PMU. Signed-off-by: Athira Rajeev Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220610134113.62991-11-atrajeev@linux.vnet.ibm.com --- .../selftests/powerpc/pmu/sampling_tests/Makefile | 2 +- .../pmu/sampling_tests/bhrb_no_crash_wo_pmu_test.c | 59 ++++++++++++++++++++++ 2 files changed, 60 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/powerpc/pmu/sampling_tests/bhrb_no_crash_wo_pmu_test.c (limited to 'tools/testing/selftests/powerpc/pmu') diff --git a/tools/testing/selftests/powerpc/pmu/sampling_tests/Makefile b/tools/testing/selftests/powerpc/pmu/sampling_tests/Makefile index f4da49d55d57..8d4839cde013 100644 --- a/tools/testing/selftests/powerpc/pmu/sampling_tests/Makefile +++ b/tools/testing/selftests/powerpc/pmu/sampling_tests/Makefile @@ -6,7 +6,7 @@ TEST_GEN_PROGS := mmcr0_exceptionbits_test mmcr0_cc56run_test mmcr0_pmccext_test mmcr1_comb_test mmcr2_l2l3_test mmcr2_fcs_fch_test \ mmcr3_src_test mmcra_thresh_marked_sample_test mmcra_thresh_cmp_test \ mmcra_bhrb_ind_call_test mmcra_bhrb_any_test mmcra_bhrb_cond_test \ - mmcra_bhrb_disable_test + mmcra_bhrb_disable_test bhrb_no_crash_wo_pmu_test top_srcdir = ../../../../../.. include ../../../lib.mk diff --git a/tools/testing/selftests/powerpc/pmu/sampling_tests/bhrb_no_crash_wo_pmu_test.c b/tools/testing/selftests/powerpc/pmu/sampling_tests/bhrb_no_crash_wo_pmu_test.c new file mode 100644 index 000000000000..4644c6782974 --- /dev/null +++ b/tools/testing/selftests/powerpc/pmu/sampling_tests/bhrb_no_crash_wo_pmu_test.c @@ -0,0 +1,59 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright 2022, Athira Rajeev, IBM Corp. + */ + +#include +#include + +#include "../event.h" +#include "misc.h" +#include "utils.h" + +/* + * A perf sampling test for making sure + * enabling branch stack doesn't crash in any + * environment, say: + * - With generic compat PMU + * - without any PMU registered + * - With platform specific PMU + * A fix for bhrb sampling crash was added in kernel + * via commit: b460b512417a ("powerpc/perf: Fix crashes + * with generic_compat_pmu & BHRB") + * + * This testcase exercises this code by doing branch + * stack enable for software event. s/w event is used + * since software event will work even in platform + * without PMU. + */ +static int bhrb_no_crash_wo_pmu_test(void) +{ + struct event event; + + /* + * Init the event for the sampling test. + * This uses software event which works on + * any platform. + */ + event_init_opts(&event, 0, PERF_TYPE_SOFTWARE, "cycles"); + + event.attr.sample_period = 1000; + event.attr.sample_type = PERF_SAMPLE_BRANCH_STACK; + event.attr.disabled = 1; + + /* + * Return code of event_open is not + * considered since test just expects no crash from + * using PERF_SAMPLE_BRANCH_STACK. Also for environment + * like generic compat PMU, branch stack is unsupported. + */ + event_open(&event); + + event_close(&event); + return 0; +} + +int main(void) +{ + return test_harness(bhrb_no_crash_wo_pmu_test, "bhrb_no_crash_wo_pmu_test"); +} -- cgit v1.2.3