cycles_with_freeze_test.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright 2014, Michael Ellerman, IBM Corp.
  4 */
  5
  6#include <stdio.h>
  7#include <stdlib.h>
  8#include <stdbool.h>
  9
 10#include "ebb.h"
 11
 12
 13/*
 14 * Test of counting cycles while using MMCR0_FC (freeze counters) to only count
 15 * parts of the code. This is complicated by the fact that FC is set by the
 16 * hardware when the event overflows. We may take the EBB after we have set FC,
 17 * so we have to be careful about whether we clear FC at the end of the EBB
 18 * handler or not.
 19 */
 20
 21static bool counters_frozen = false;
 22static int ebbs_while_frozen = 0;
 23
 24static void ebb_callee(void)
 25{
 26	uint64_t mask, val;
 27
 28	mask = MMCR0_PMAO | MMCR0_FC;
 29
 30	val = mfspr(SPRN_BESCR);
 31	if (!(val & BESCR_PMEO)) {
 32		ebb_state.stats.spurious++;
 33		goto out;
 34	}
 35
 36	ebb_state.stats.ebb_count++;
 37	trace_log_counter(ebb_state.trace, ebb_state.stats.ebb_count);
 38
 39	val = mfspr(SPRN_MMCR0);
 40	trace_log_reg(ebb_state.trace, SPRN_MMCR0, val);
 41
 42	if (counters_frozen) {
 43		trace_log_string(ebb_state.trace, "frozen");
 44		ebbs_while_frozen++;
 45		mask &= ~MMCR0_FC;
 46	}
 47
 48	count_pmc(1, sample_period);
 49out:
 50	reset_ebb_with_clear_mask(mask);
 51}
 52
 53int cycles_with_freeze(void)
 54{
 55	struct event event;
 56	uint64_t val;
 57	bool fc_cleared;
 58
 59	SKIP_IF(!ebb_is_supported());
 60
 61	event_init_named(&event, 0x1001e, "cycles");
 62	event_leader_ebb_init(&event);
 63
 64	event.attr.exclude_kernel = 1;
 65	event.attr.exclude_hv = 1;
 66	event.attr.exclude_idle = 1;
 67
 68	FAIL_IF(event_open(&event));
 69
 70	setup_ebb_handler(ebb_callee);
 71	ebb_global_enable();
 72	FAIL_IF(ebb_event_enable(&event));
 73
 74	mtspr(SPRN_PMC1, pmc_sample_period(sample_period));
 75
 76	fc_cleared = false;
 77
 78	/* Make sure we loop until we take at least one EBB */
 79	while ((ebb_state.stats.ebb_count < 20 && !fc_cleared) ||
 80		ebb_state.stats.ebb_count < 1)
 81	{
 82		counters_frozen = false;
 83		mb();
 84		mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) & ~MMCR0_FC);
 85
 86		FAIL_IF(core_busy_loop());
 87
 88		counters_frozen = true;
 89		mb();
 90		mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) |  MMCR0_FC);
 91
 92		val = mfspr(SPRN_MMCR0);
 93		if (! (val & MMCR0_FC)) {
 94			printf("Outside of loop, FC NOT set MMCR0 0x%lx\n", val);
 95			fc_cleared = true;
 96		}
 97	}
 98
 99	ebb_global_disable();
100	ebb_freeze_pmcs();
101
102	dump_ebb_state();
103
104	printf("EBBs while frozen %d\n", ebbs_while_frozen);
105
106	event_close(&event);
107
108	FAIL_IF(ebb_state.stats.ebb_count == 0);
109	FAIL_IF(fc_cleared);
110
111	return 0;
112}
113
114int main(void)
115{
116	return test_harness(cycles_with_freeze, "cycles_with_freeze");
117}