selftests/powerpc/pmu: Add interface test for mmcra_thresh_cmp fields

The testcase uses event code 0x35340401e0 for load only sampling, to
verify the settings of thresh compare field in Monitor Mode Control
Register A (MMCRA: 9-18 bits for power9 and MMCRA: 8-18 bits for
power10). Testcase checks if the thresh compare field is programmed
correctly via perf interface to MMCRA register.
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220610134113.62991-4-atrajeev@linux.vnet.ibm.com

tools/testing/selftests/powerpc/pmu/sampling_tests/Makefile

@@ -4,7 +4,7 @@ CFLAGS += -m64
 TEST_GEN_PROGS := mmcr0_exceptionbits_test mmcr0_cc56run_test mmcr0_pmccext_test \
 		   mmcr0_pmcjce_test mmcr0_fc56_pmc1ce_test mmcr0_fc56_pmc56_test \
 		   mmcr1_comb_test mmcr2_l2l3_test mmcr2_fcs_fch_test \
-		   mmcr3_src_test mmcra_thresh_marked_sample_test
+		   mmcr3_src_test mmcra_thresh_marked_sample_test mmcra_thresh_cmp_test
 
 top_srcdir = ../../../../../..
 include ../../../lib.mk

tools/testing/selftests/powerpc/pmu/sampling_tests/mmcra_thresh_cmp_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 "misc.h"
+#include "utils.h"
+
+/*
+ * Primary PMU event used here is PM_MRK_INST_CMPL (0x401e0)
+ * Threshold event selection used is issue to complete for cycles
+ * Sampling criteria is Load only sampling
+ */
+#define p9_EventCode 0x13E35340401e0
+#define p10_EventCode 0x35340401e0
+
+extern void thirty_two_instruction_loop_with_ll_sc(u64 loops, u64 *ll_sc_target);
+
+/* A perf sampling test to test mmcra fields */
+static int mmcra_thresh_cmp(void)
+{
+	struct event event;
+	u64 *intr_regs;
+	u64 dummy;
+
+	/* Check for platform support for the test */
+	SKIP_IF(check_pvr_for_sampling_tests());
+
+	/* Skip for comapt mode */
+	SKIP_IF(check_for_compat_mode());
+
+	/* Init the event for the sampling test */
+	if (!have_hwcap2(PPC_FEATURE2_ARCH_3_1)) {
+		event_init_sampling(&event, p9_EventCode);
+	} else {
+		event_init_sampling(&event, p10_EventCode);
+		event.attr.config1 = 1000;
+	}
+
+	event.attr.sample_regs_intr = platform_extended_mask;
+	FAIL_IF(event_open(&event));
+	event.mmap_buffer = event_sample_buf_mmap(event.fd, 1);
+
+	FAIL_IF(event_enable(&event));
+
+	/* workload to make the event overflow */
+	thirty_two_instruction_loop_with_ll_sc(1000000, &dummy);
+
+	FAIL_IF(event_disable(&event));
+
+	/* Check for sample count */
+	FAIL_IF(!collect_samples(event.mmap_buffer));
+
+	intr_regs = get_intr_regs(&event, event.mmap_buffer);
+
+	/* Check for intr_regs */
+	FAIL_IF(!intr_regs);
+
+	/* Verify that thresh cmp match with the corresponding event code fields */
+	FAIL_IF(get_thresh_cmp_val(event) !=
+			get_mmcra_thd_cmp(get_reg_value(intr_regs, "MMCRA"), 4));
+
+	event_close(&event);
+	return 0;
+}
+
+int main(void)
+{
+	FAIL_IF(test_harness(mmcra_thresh_cmp, "mmcra_thresh_cmp"));
+}