selftests/powerpc/pmu: Add interface test for mmcra_ifm field for conditional branch type

The testcase uses "instructions" event to check if the
Instruction filtering mode(IFM) bits are programmed correctly
for conditional branch type. Testcase checks if IFM bits is
programmed correctly to Monitor Mode Control Register A (MMCRA)
via perf interface for ISA v3.1 platform.
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220610134113.62991-8-atrajeev@linux.vnet.ibm.com

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

@@ -5,7 +5,7 @@ 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 mmcra_thresh_cmp_test \
-		   mmcra_bhrb_ind_call_test mmcra_bhrb_any_test
+		   mmcra_bhrb_ind_call_test mmcra_bhrb_any_test mmcra_bhrb_cond_test
 
 top_srcdir = ../../../../../..
 include ../../../lib.mk

tools/testing/selftests/powerpc/pmu/sampling_tests/mmcra_bhrb_cond_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"
+
+extern void thirty_two_instruction_loop(int loops);
+
+/* Instructions */
+#define EventCode 0x500fa
+
+/* ifm field for conditional branch mode */
+#define IFM_COND_BRANCH 0x3
+
+/*
+ * A perf sampling test for mmcra
+ * field: ifm for bhrb cond call.
+ */
+static int mmcra_bhrb_cond_test(void)
+{
+	struct event event;
+	u64 *intr_regs;
+
+	/*
+	 * Check for platform support for the test.
+	 * This test is only aplicable on power10
+	 */
+	SKIP_IF(check_pvr_for_sampling_tests());
+	SKIP_IF(!have_hwcap2(PPC_FEATURE2_ARCH_3_1));
+
+	 /* Init the event for the sampling test */
+	event_init_sampling(&event, EventCode);
+	event.attr.sample_regs_intr = platform_extended_mask;
+	event.attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+	event.attr.branch_sample_type = PERF_SAMPLE_BRANCH_COND;
+	event.attr.exclude_kernel = 1;
+
+	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(10000);
+
+	FAIL_IF(event_disable(&event));
+
+	intr_regs = get_intr_regs(&event, event.mmap_buffer);
+
+	/* Check for intr_regs */
+	FAIL_IF(!intr_regs);
+
+	/* Verify that ifm bit is set properly in MMCRA */
+	FAIL_IF(get_mmcra_ifm(get_reg_value(intr_regs, "MMCRA"), 5) != IFM_COND_BRANCH);
+
+	event_close(&event);
+	return 0;
+}
+
+int main(void)
+{
+	return test_harness(mmcra_bhrb_cond_test, "mmcra_bhrb_cond_test");
+}