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}
118