selftests/powerpc/pmu: Add selftest for group constraint check for MMCRA thresh_ctl field

Thresh control bits in the event code is used to program thresh_ctl
field in Monitor Mode Control Register A (MMCRA: 48-55). When scheduling
events as a group, all events in that group should match value in these
bits. Otherwise event open for the sibling events will fail.

Testcase uses event code PM_MRK_INST_CMPL (0x401e0) as leader and
another event PM_THRESH_MET (101ec) as sibling event, and checks if
group constraint checks for thresh_ctl field added correctly via perf
interface.

Signed-off-by: Kajol Jain <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

tools/testing/selftests/powerpc/pmu/event_code_tests/Makefile

···
 	group_constraint_mmcra_sample_test invalid_event_code_test reserved_bits_mmcra_thresh_ctl_test \
 	blacklisted_events_test event_alternatives_tests_p9 event_alternatives_tests_p10 generic_events_valid_test \
 	group_constraint_l2l3_sel_test group_constraint_cache_test group_constraint_thresh_cmp_test \
-	group_constraint_unit_test
+	group_constraint_unit_test group_constraint_thresh_ctl_test
 
 top_srcdir = ../../../../../..
 include ../../../lib.mk

tools/testing/selftests/powerpc/pmu/event_code_tests/group_constraint_thresh_ctl_test.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2022, Kajol Jain, IBM Corp.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "../event.h"
+#include "utils.h"
+#include "../sampling_tests/misc.h"
+
+/*
+ * Primary PMU events used here are PM_MRK_INST_CMPL (0x401e0) and
+ * PM_THRESH_MET (0x101ec).
+ * Threshold event selection used is issue to complete and issue to
+ * finished for cycles
+ * Sampling criteria is Load or Store only sampling
+ */
+#define EventCode_1 0x35340401e0
+#define EventCode_2 0x34340101ec
+#define EventCode_3 0x35340101ec
+
+/*
+ * Testcase for group constraint check of thresh_ctl bits which is
+ * used to program thresh compare field in Monitor Mode Control Register A
+ * (MMCR0: 48-55).
+ * All events in the group should match thresh ctl bits otherwise
+ * event_open for the group will fail.
+ */
+static int group_constraint_thresh_ctl(void)
+{
+	struct event event, leader;
+
+	/* Check for platform support for the test */
+	SKIP_IF(platform_check_for_tests());
+
+	/* Init the events for the group contraint thresh control test */
+	event_init(&leader, EventCode_1);
+	FAIL_IF(event_open(&leader));
+
+	event_init(&event, EventCode_2);
+
+	/* Expected to fail as sibling and leader event request different thresh_ctl bits */
+	FAIL_IF(!event_open_with_group(&event, leader.fd));
+
+	event_close(&event);
+
+	/* Init the event for the group contraint thresh control test */
+	event_init(&event, EventCode_3);
+
+	 /* Expected to succeed as sibling and leader event request same thresh_ctl bits */
+	FAIL_IF(event_open_with_group(&event, leader.fd));
+
+	event_close(&leader);
+	event_close(&event);
+
+	return 0;
+}
+
+int main(void)
+{
+	return test_harness(group_constraint_thresh_ctl, "group_constraint_thresh_ctl");
+}