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 
24 static struct event event;
25 
child(void)26 static 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 */
fork_cleanup(void)42 int 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 
main(void)77 int main(void)
78 {
79 	return test_harness(fork_cleanup, "fork_cleanup");
80 }
81