selftests/powerpc/pmu: Add interface test for mmcra_ifm field of indirect call type

The testcase uses "instructions" event to check if the
Instruction filtering mode(IFM) bits are programmed correctly
for indirect branch type. Testcase checks if IFM bits are
programmed correctly to Monitor Mode Control Register A (MMCRA)
via perf interface for ISA v3.1 platform.

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/branch_loops.S

···
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2022, Kajol Jain, IBM Corp.
+ */
+
+#include <ppc-asm.h>
+
+	.text
+
+#define ITER_SHIFT	31
+
+FUNC_START(indirect_branch_loop)
+	li	r3, 1
+	sldi	r3, r3, ITER_SHIFT
+
+1:	cmpdi	r3, 0
+	beqlr
+
+	addi	r3, r3, -1
+
+	ld	r4, 2f@got(%r2)
+	mtctr	r4
+	bctr
+
+	.balign 32
+2:	b	1b
+
+FUNC_END(indirect_branch_loop)

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

···
 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
+		   mmcr3_src_test mmcra_thresh_marked_sample_test mmcra_thresh_cmp_test \
+		   mmcra_bhrb_ind_call_test
 
 top_srcdir = ../../../../../..
 include ../../../lib.mk
 
-$(TEST_GEN_PROGS): ../../harness.c ../../utils.c ../event.c ../lib.c misc.c misc.h ../loop.S
+$(TEST_GEN_PROGS): ../../harness.c ../../utils.c ../event.c ../lib.c misc.c misc.h ../loop.S ../branch_loops.S

tools/testing/selftests/powerpc/pmu/sampling_tests/mmcra_bhrb_ind_call_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 indirect_branch_loop(void);
+
+/* Instructions */
+#define EventCode 0x500fa
+
+/* ifm field for indirect branch mode */
+#define IFM_IND_BRANCH 0x2
+
+/*
+ * A perf sampling test for mmcra
+ * field: ifm for bhrb ind_call.
+ */
+static int mmcra_bhrb_ind_call_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_IND_CALL;
+	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 */
+	indirect_branch_loop();
+
+	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_IND_BRANCH);
+
+	event_close(&event);
+	return 0;
+}
+
+int main(void)
+{
+	return test_harness(mmcra_bhrb_ind_call_test, "mmcra_bhrb_ind_call_test");
+}