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(tb: ebb_state.trace, value: ebb_state.stats.ebb_count);
38
39 val = mfspr(SPRN_MMCR0);
40 trace_log_reg(tb: ebb_state.trace, reg: SPRN_MMCR0, value: val);
41
42 if (counters_frozen) {
43 trace_log_string(tb: ebb_state.trace, str: "frozen");
44 ebbs_while_frozen++;
45 mask &= ~MMCR0_FC;
46 }
47
48 count_pmc(pmc: 1, sample_period);
49out:
50 reset_ebb_with_clear_mask(mmcr0_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(e: &event, config: 0x1001e, name: "cycles");
62 event_leader_ebb_init(e: &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(e: &event));
69
70 setup_ebb_handler(ebb_callee);
71 ebb_global_enable();
72 FAIL_IF(ebb_event_enable(e: &event));
73
74 mtspr(SPRN_PMC1, pmc_sample_period(value: 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(e: &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

source code of linux/tools/testing/selftests/powerpc/pmu/ebb/cycles_with_freeze_test.c