1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright 2014, Michael Ellerman, IBM Corp.
4 */
5
6#include <signal.h>
7#include <stdio.h>
8#include <stdlib.h>
9#include <stdbool.h>
10#include <sys/types.h>
11#include <sys/wait.h>
12#include <unistd.h>
13#include <setjmp.h>
14
15#include "ebb.h"
16
17
18/*
19 * Test that a fork clears the PMU state of the child. eg. BESCR/EBBHR/EBBRR
20 * are cleared, and MMCR0_PMCC is reset, preventing the child from accessing
21 * the PMU.
22 */
23
24static struct event event;
25
26static int child(void)
27{
28	/* Even though we have EBE=0 we can still see the EBB regs */
29	FAIL_IF(mfspr(SPRN_BESCR) != 0);
30	FAIL_IF(mfspr(SPRN_EBBHR) != 0);
31	FAIL_IF(mfspr(SPRN_EBBRR) != 0);
32
33	FAIL_IF(catch_sigill(write_pmc1));
34
35	/* We can still read from the event, though it is on our parent */
36	FAIL_IF(event_read(&event));
37
38	return 0;
39}
40
41/* Tests that fork clears EBB state */
42int fork_cleanup(void)
43{
44	pid_t pid;
45
46	SKIP_IF(!ebb_is_supported());
47
48	event_init_named(&event, 0x1001e, "cycles");
49	event_leader_ebb_init(&event);
50
51	FAIL_IF(event_open(&event));
52
53	ebb_enable_pmc_counting(1);
54	setup_ebb_handler(standard_ebb_callee);
55	ebb_global_enable();
56
57	FAIL_IF(ebb_event_enable(&event));
58
59	mtspr(SPRN_MMCR0, MMCR0_FC);
60	mtspr(SPRN_PMC1, pmc_sample_period(sample_period));
61
62	/* Don't need to actually take any EBBs */
63
64	pid = fork();
65	if (pid == 0)
66		exit(child());
67
68	/* Child does the actual testing */
69	FAIL_IF(wait_for_child(pid));
70
71	/* After fork */
72	event_close(&event);
73
74	return 0;
75}
76
77int main(void)
78{
79	return test_harness(fork_cleanup, "fork_cleanup");
80}
81