selftests/powerpc/pmu: Add selftest for event alternatives for power9

Platform specific PMU supports alternative event for some of the event
codes. During perf_event_open, it any event group doesn't match
constraint check criteria, further lookup is done to find alternative
event. Code checks to see if it is possible to schedule event as group
using alternative events.

Testcase exercises the alternative event find code for power9. Example,
since events in same PMC can't go in as a group, ideally using
PM_RUN_CYC_ALT (0x200f4) and PM_BR_TAKEN_CMPL (0x200fa) will fail. But
since RUN_CYC (0x600f4) is alternative event for 0x200f4, it is possible
to use 0x600f4 and 0x200fa as group. Testcase uses such combination for
all events in power9 which has an alternative event.
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220610134113.62991-27-atrajeev@linux.vnet.ibm.com

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

@@ -4,7 +4,7 @@ CFLAGS += -m64
 TEST_GEN_PROGS := group_constraint_pmc56_test group_pmc56_exclude_constraints_test group_constraint_pmc_count_test \
 	group_constraint_repeat_test group_constraint_radix_scope_qual_test reserved_bits_mmcra_sample_elig_mode_test \
 	group_constraint_mmcra_sample_test invalid_event_code_test reserved_bits_mmcra_thresh_ctl_test \
-	blacklisted_events_test
+	blacklisted_events_test event_alternatives_tests_p9
 
 top_srcdir = ../../../../../..
 include ../../../lib.mk

tools/testing/selftests/powerpc/pmu/event_code_tests/event_alternatives_tests_p9.c

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2022, Athira Rajeev, IBM Corp.
+ */
+
+#include <stdio.h>
+#include "../event.h"
+#include "../sampling_tests/misc.h"
+
+#define PM_RUN_CYC_ALT 0x200f4
+#define PM_INST_DISP 0x200f2
+#define PM_BR_2PATH 0x20036
+#define PM_LD_MISS_L1 0x3e054
+#define PM_RUN_INST_CMPL_ALT 0x400fa
+
+#define EventCode_1 0x200fa
+#define EventCode_2 0x200fc
+#define EventCode_3 0x300fc
+#define EventCode_4 0x400fc
+
+/*
+ * Check for event alternatives.
+ */
+
+static int event_alternatives_tests_p9(void)
+{
+	struct event event, leader;
+
+	/* Check for platform support for the test */
+	SKIP_IF(platform_check_for_tests());
+
+	/*
+	 * PVR check is used here since PMU specific data like
+	 * alternative events is handled by respective PMU driver
+	 * code and using PVR will work correctly for all cases
+	 * including generic compat mode.
+	 */
+	SKIP_IF(PVR_VER(mfspr(SPRN_PVR)) != POWER9);
+
+	/* Skip for generic compat PMU */
+	SKIP_IF(check_for_generic_compat_pmu());
+
+	/* Init the event for PM_RUN_CYC_ALT */
+	event_init(&leader, PM_RUN_CYC_ALT);
+	FAIL_IF(event_open(&leader));
+
+	event_init(&event, EventCode_1);
+
+	/*
+	 * Expected to pass since PM_RUN_CYC_ALT in PMC2 has alternative event
+	 * 0x600f4. So it can go in with EventCode_1 which is using PMC2
+	 */
+	FAIL_IF(event_open_with_group(&event, leader.fd));
+
+	event_close(&leader);
+	event_close(&event);
+
+	event_init(&leader, PM_INST_DISP);
+	FAIL_IF(event_open(&leader));
+
+	event_init(&event, EventCode_2);
+	/*
+	 * Expected to pass since PM_INST_DISP in PMC2 has alternative event
+	 * 0x300f2 in PMC3. So it can go in with EventCode_2 which is using PMC2
+	 */
+	FAIL_IF(event_open_with_group(&event, leader.fd));
+
+	event_close(&leader);
+	event_close(&event);
+
+	event_init(&leader, PM_BR_2PATH);
+	FAIL_IF(event_open(&leader));
+
+	event_init(&event, EventCode_2);
+	/*
+	 * Expected to pass since PM_BR_2PATH in PMC2 has alternative event
+	 * 0x40036 in PMC4. So it can go in with EventCode_2 which is using PMC2
+	 */
+	FAIL_IF(event_open_with_group(&event, leader.fd));
+
+	event_close(&leader);
+	event_close(&event);
+
+	event_init(&leader, PM_LD_MISS_L1);
+	FAIL_IF(event_open(&leader));
+
+	event_init(&event, EventCode_3);
+	/*
+	 * Expected to pass since PM_LD_MISS_L1 in PMC3 has alternative event
+	 * 0x400f0 in PMC4. So it can go in with EventCode_3 which is using PMC3
+	 */
+	FAIL_IF(event_open_with_group(&event, leader.fd));
+
+	event_close(&leader);
+	event_close(&event);
+
+	event_init(&leader, PM_RUN_INST_CMPL_ALT);
+	FAIL_IF(event_open(&leader));
+
+	event_init(&event, EventCode_4);
+	/*
+	 * Expected to pass since PM_RUN_INST_CMPL_ALT in PMC4 has alternative event
+	 * 0x500fa in PMC5. So it can go in with EventCode_4 which is using PMC4
+	 */
+	FAIL_IF(event_open_with_group(&event, leader.fd));
+
+	event_close(&leader);
+	event_close(&event);
+
+	return 0;
+}
+
+int main(void)
+{
+	return test_harness(event_alternatives_tests_p9, "event_alternatives_tests_p9");
+}