1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright 2014, Michael Ellerman, IBM Corp.
4 */
5
6#define _GNU_SOURCE
7
8#include <stdio.h>
9#include <stdbool.h>
10#include <string.h>
11#include <sys/prctl.h>
12
13#include "ebb.h"
14
15
16/*
17 * Run a calibrated instruction loop and count instructions executed using
18 * EBBs. Make sure the counts look right.
19 */
20
21extern void thirty_two_instruction_loop(uint64_t loops);
22
23static bool counters_frozen = true;
24
25static int do_count_loop(struct event *event, uint64_t instructions,
26			 uint64_t overhead, bool report)
27{
28	int64_t difference, expected;
29	double percentage;
30
31	clear_ebb_stats();
32
33	counters_frozen = false;
34	mb();
35	mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) & ~MMCR0_FC);
36
37	thirty_two_instruction_loop(instructions >> 5);
38
39	counters_frozen = true;
40	mb();
41	mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) | MMCR0_FC);
42
43	count_pmc(4, sample_period);
44
45	event->result.value = ebb_state.stats.pmc_count[4-1];
46	expected = instructions + overhead;
47	difference = event->result.value - expected;
48	percentage = (double)difference / event->result.value * 100;
49
50	if (report) {
51		printf("Looped for %lu instructions, overhead %lu\n", instructions, overhead);
52		printf("Expected %lu\n", expected);
53		printf("Actual   %llu\n", event->result.value);
54		printf("Delta    %ld, %f%%\n", difference, percentage);
55		printf("Took %d EBBs\n", ebb_state.stats.ebb_count);
56	}
57
58	if (difference < 0)
59		difference = -difference;
60
61	/* Tolerate a difference of up to 0.0001 % */
62	difference *= 10000 * 100;
63	if (difference / event->result.value)
64		return -1;
65
66	return 0;
67}
68
69/* Count how many instructions it takes to do a null loop */
70static uint64_t determine_overhead(struct event *event)
71{
72	uint64_t current, overhead;
73	int i;
74
75	do_count_loop(event, 0, 0, false);
76	overhead = event->result.value;
77
78	for (i = 0; i < 100; i++) {
79		do_count_loop(event, 0, 0, false);
80		current = event->result.value;
81		if (current < overhead) {
82			printf("Replacing overhead %lu with %lu\n", overhead, current);
83			overhead = current;
84		}
85	}
86
87	return overhead;
88}
89
90static void pmc4_ebb_callee(void)
91{
92	uint64_t val;
93
94	val = mfspr(SPRN_BESCR);
95	if (!(val & BESCR_PMEO)) {
96		ebb_state.stats.spurious++;
97		goto out;
98	}
99
100	ebb_state.stats.ebb_count++;
101	count_pmc(4, sample_period);
102out:
103	if (counters_frozen)
104		reset_ebb_with_clear_mask(MMCR0_PMAO);
105	else
106		reset_ebb();
107}
108
109int instruction_count(void)
110{
111	struct event event;
112	uint64_t overhead;
113
114	SKIP_IF(!ebb_is_supported());
115
116	event_init_named(&event, 0x400FA, "PM_RUN_INST_CMPL");
117	event_leader_ebb_init(&event);
118	event.attr.exclude_kernel = 1;
119	event.attr.exclude_hv = 1;
120	event.attr.exclude_idle = 1;
121
122	FAIL_IF(event_open(&event));
123	FAIL_IF(ebb_event_enable(&event));
124
125	sample_period = COUNTER_OVERFLOW;
126
127	setup_ebb_handler(pmc4_ebb_callee);
128	mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) & ~MMCR0_FC);
129	ebb_global_enable();
130
131	overhead = determine_overhead(&event);
132	printf("Overhead of null loop: %lu instructions\n", overhead);
133
134	/* Run for 1M instructions */
135	FAIL_IF(do_count_loop(&event, 0x100000, overhead, true));
136
137	/* Run for 10M instructions */
138	FAIL_IF(do_count_loop(&event, 0xa00000, overhead, true));
139
140	/* Run for 100M instructions */
141	FAIL_IF(do_count_loop(&event, 0x6400000, overhead, true));
142
143	/* Run for 1G instructions */
144	FAIL_IF(do_count_loop(&event, 0x40000000, overhead, true));
145
146	/* Run for 16G instructions */
147	FAIL_IF(do_count_loop(&event, 0x400000000, overhead, true));
148
149	/* Run for 64G instructions */
150	FAIL_IF(do_count_loop(&event, 0x1000000000, overhead, true));
151
152	/* Run for 128G instructions */
153	FAIL_IF(do_count_loop(&event, 0x2000000000, overhead, true));
154
155	ebb_global_disable();
156	event_close(&event);
157
158	printf("Finished OK\n");
159
160	return 0;
161}
162
163int main(void)
164{
165	test_harness_set_timeout(300);
166	return test_harness(instruction_count, "instruction_count");
167}
168