1/*
2 * Copyright 2014, Michael Ellerman, IBM Corp.
3 * Licensed under GPLv2.
4 */
5
6#include <stdbool.h>
7#include <stdio.h>
8#include <stdlib.h>
9
10#include "ebb.h"
11
12
13#define NUMBER_OF_EBBS	50
14
15/*
16 * Test that if we overflow the counter while in the EBB handler, we take
17 * another EBB on exiting from the handler.
18 *
19 * We do this by counting with a stupidly low sample period, causing us to
20 * overflow the PMU while we're still in the EBB handler, leading to another
21 * EBB.
22 *
23 * We get out of what would otherwise be an infinite loop by leaving the
24 * counter frozen once we've taken enough EBBs.
25 */
26
27static void ebb_callee(void)
28{
29	uint64_t siar, val;
30
31	val = mfspr(SPRN_BESCR);
32	if (!(val & BESCR_PMEO)) {
33		ebb_state.stats.spurious++;
34		goto out;
35	}
36
37	ebb_state.stats.ebb_count++;
38	trace_log_counter(ebb_state.trace, ebb_state.stats.ebb_count);
39
40	/* Resets the PMC */
41	count_pmc(1, sample_period);
42
43out:
44	if (ebb_state.stats.ebb_count == NUMBER_OF_EBBS)
45		/* Reset but leave counters frozen */
46		reset_ebb_with_clear_mask(MMCR0_PMAO);
47	else
48		/* Unfreezes */
49		reset_ebb();
50
51	/* Do some stuff to chew some cycles and pop the counter */
52	siar = mfspr(SPRN_SIAR);
53	trace_log_reg(ebb_state.trace, SPRN_SIAR, siar);
54
55	val = mfspr(SPRN_PMC1);
56	trace_log_reg(ebb_state.trace, SPRN_PMC1, val);
57
58	val = mfspr(SPRN_MMCR0);
59	trace_log_reg(ebb_state.trace, SPRN_MMCR0, val);
60}
61
62int back_to_back_ebbs(void)
63{
64	struct event event;
65
66	event_init_named(&event, 0x1001e, "cycles");
67	event_leader_ebb_init(&event);
68
69	event.attr.exclude_kernel = 1;
70	event.attr.exclude_hv = 1;
71	event.attr.exclude_idle = 1;
72
73	FAIL_IF(event_open(&event));
74
75	setup_ebb_handler(ebb_callee);
76
77	FAIL_IF(ebb_event_enable(&event));
78
79	sample_period = 5;
80
81	ebb_freeze_pmcs();
82	mtspr(SPRN_PMC1, pmc_sample_period(sample_period));
83	ebb_global_enable();
84	ebb_unfreeze_pmcs();
85
86	while (ebb_state.stats.ebb_count < NUMBER_OF_EBBS)
87		FAIL_IF(core_busy_loop());
88
89	ebb_global_disable();
90	ebb_freeze_pmcs();
91
92	count_pmc(1, sample_period);
93
94	dump_ebb_state();
95
96	event_close(&event);
97
98	FAIL_IF(ebb_state.stats.ebb_count != NUMBER_OF_EBBS);
99
100	return 0;
101}
102
103int main(void)
104{
105	return test_harness(back_to_back_ebbs, "back_to_back_ebbs");
106}
107