bhrb_no_crash_wo_pmu_test.c

 1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * Copyright 2022, Athira Rajeev, IBM Corp.
 4 */
 5
 6#include <stdio.h>
 7#include <stdlib.h>
 8
 9#include "../event.h"
10#include "misc.h"
11#include "utils.h"
12
13/*
14 * A perf sampling test for making sure
15 * enabling branch stack doesn't crash in any
16 * environment, say:
17 *  - With generic compat PMU
18 *  - without any PMU registered
19 *  - With platform specific PMU
20 *  A fix for bhrb sampling crash was added in kernel
21 *  via commit: b460b512417a ("powerpc/perf: Fix crashes
22 *  with generic_compat_pmu & BHRB")
23 *
24 * This testcase exercises this code by doing branch
25 * stack enable for software event. s/w event is used
26 * since software event will work even in platform
27 * without PMU.
28 */
29static int bhrb_no_crash_wo_pmu_test(void)
30{
31	struct event event;
32
33	/*
34	 * Init the event for the sampling test.
35	 * This uses software event which works on
36	 * any platform.
37	 */
38	event_init_opts(&event, 0, PERF_TYPE_SOFTWARE, "cycles");
39
40	event.attr.sample_period = 1000;
41	event.attr.sample_type = PERF_SAMPLE_BRANCH_STACK;
42	event.attr.disabled = 1;
43
44	/*
45	 * Return code of event_open is not
46	 * considered since test just expects no crash from
47	 * using PERF_SAMPLE_BRANCH_STACK. Also for environment
48	 * like generic compat PMU, branch stack is unsupported.
49	 */
50	event_open(&event);
51
52	event_close(&event);
53	return 0;
54}
55
56int main(void)
57{
58	return test_harness(bhrb_no_crash_wo_pmu_test, "bhrb_no_crash_wo_pmu_test");
59}