1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2021 Facebook */
3 #define _GNU_SOURCE
4 #include <pthread.h>
5 #include <sched.h>
6 #include <test_progs.h>
7 #include "test_perf_link.skel.h"
8 
9 static void burn_cpu(void)
10 {
11 	volatile int j = 0;
12 	cpu_set_t cpu_set;
13 	int i, err;
14 
15 	/* generate some branches on cpu 0 */
16 	CPU_ZERO(&cpu_set);
17 	CPU_SET(0, &cpu_set);
18 	err = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set), &cpu_set);
19 	ASSERT_OK(err, "set_thread_affinity");
20 
21 	/* spin the loop for a while (random high number) */
22 	for (i = 0; i < 1000000; ++i)
23 		++j;
24 }
25 
26 /* TODO: often fails in concurrent mode */
27 void serial_test_perf_link(void)
28 {
29 	struct test_perf_link *skel = NULL;
30 	struct perf_event_attr attr;
31 	int pfd = -1, link_fd = -1, err;
32 	int run_cnt_before, run_cnt_after;
33 	struct bpf_link_info info;
34 	__u32 info_len = sizeof(info);
35 
36 	/* create perf event */
37 	memset(&attr, 0, sizeof(attr));
38 	attr.size = sizeof(attr);
39 	attr.type = PERF_TYPE_SOFTWARE;
40 	attr.config = PERF_COUNT_SW_CPU_CLOCK;
41 	attr.freq = 1;
42 	attr.sample_freq = 1000;
43 	pfd = syscall(__NR_perf_event_open, &attr, -1, 0, -1, PERF_FLAG_FD_CLOEXEC);
44 	if (!ASSERT_GE(pfd, 0, "perf_fd"))
45 		goto cleanup;
46 
47 	skel = test_perf_link__open_and_load();
48 	if (!ASSERT_OK_PTR(skel, "skel_load"))
49 		goto cleanup;
50 
51 	link_fd = bpf_link_create(bpf_program__fd(skel->progs.handler), pfd,
52 				  BPF_PERF_EVENT, NULL);
53 	if (!ASSERT_GE(link_fd, 0, "link_fd"))
54 		goto cleanup;
55 
56 	memset(&info, 0, sizeof(info));
57 	err = bpf_link_get_info_by_fd(link_fd, &info, &info_len);
58 	if (!ASSERT_OK(err, "link_get_info"))
59 		goto cleanup;
60 
61 	ASSERT_EQ(info.type, BPF_LINK_TYPE_PERF_EVENT, "link_type");
62 	ASSERT_GT(info.id, 0, "link_id");
63 	ASSERT_GT(info.prog_id, 0, "link_prog_id");
64 
65 	/* ensure we get at least one perf_event prog execution */
66 	burn_cpu();
67 	ASSERT_GT(skel->bss->run_cnt, 0, "run_cnt");
68 
69 	/* perf_event is still active, but we close link and BPF program
70 	 * shouldn't be executed anymore
71 	 */
72 	close(link_fd);
73 	link_fd = -1;
74 
75 	/* make sure there are no stragglers */
76 	kern_sync_rcu();
77 
78 	run_cnt_before = skel->bss->run_cnt;
79 	burn_cpu();
80 	run_cnt_after = skel->bss->run_cnt;
81 
82 	ASSERT_EQ(run_cnt_before, run_cnt_after, "run_cnt_before_after");
83 
84 cleanup:
85 	if (link_fd >= 0)
86 		close(link_fd);
87 	if (pfd >= 0)
88 		close(pfd);
89 	test_perf_link__destroy(skel);
90 }
91