selftests/powerpc/pmu: Add interface test for bhrb disable field

The testcase uses "instructions" event to generate the
samples and fetch Monitor Mode Control Register A (MMCRA)
when overflow. Branch History Rolling Buffer(bhrb) disable bit
is part of MMCRA which need to be verified by perf interface.
Testcase checks if the bhrb disable bit of MMCRA register is
programmed correctly via perf interface for ISA v3.1 platform
Also make get_mmcra_ifm return type as u64.

Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220610134113.62991-9-atrajeev@linux.vnet.ibm.com

1 files changed, 66 insertions, 0 deletions

diff --git a/tools/testing/selftests/powerpc/pmu/sampling_tests/mmcra_bhrb_disable_test.c b/tools/testing/selftests/powerpc/pmu/sampling_tests/mmcra_bhrb_disable_test.c
new file mode 100644
index 000000000000..186a853c0f62
--- /dev/null
+++ b/tools/testing/selftests/powerpc/pmu/sampling_tests/mmcra_bhrb_disable_test.c
@@ -0,0 +1,66 @@
+// 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
+
+/*
+ * A perf sampling test for mmcra
+ * field: bhrb_disable.
+ */
+static int mmcra_bhrb_disable_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_ANY;
+	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 bhrb_disable bit is set in MMCRA */
+	FAIL_IF(get_mmcra_bhrb_disable(get_reg_value(intr_regs, "MMCRA"), 5));
+
+	event_close(&event);
+	return 0;
+}
+
+int main(void)
+{
+	return test_harness(mmcra_bhrb_disable_test, "mmcra_bhrb_disable_test");
+}