1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2021 Facebook */
3 #include <test_progs.h>
4 #include "get_branch_snapshot.skel.h"
5 
6 static int *pfd_array;
7 static int cpu_cnt;
8 
9 static bool is_hypervisor(void)
10 {
11 	char *line = NULL;
12 	bool ret = false;
13 	size_t len;
14 	FILE *fp;
15 
16 	fp = fopen("/proc/cpuinfo", "r");
17 	if (!fp)
18 		return false;
19 
20 	while (getline(&line, &len, fp) != -1) {
21 		if (!strncmp(line, "flags", 5)) {
22 			if (strstr(line, "hypervisor") != NULL)
23 				ret = true;
24 			break;
25 		}
26 	}
27 
28 	free(line);
29 	fclose(fp);
30 	return ret;
31 }
32 
33 static int create_perf_events(void)
34 {
35 	struct perf_event_attr attr = {0};
36 	int cpu;
37 
38 	/* create perf event */
39 	attr.size = sizeof(attr);
40 	attr.type = PERF_TYPE_HARDWARE;
41 	attr.config = PERF_COUNT_HW_CPU_CYCLES;
42 	attr.sample_type = PERF_SAMPLE_BRANCH_STACK;
43 	attr.branch_sample_type = PERF_SAMPLE_BRANCH_KERNEL |
44 		PERF_SAMPLE_BRANCH_USER | PERF_SAMPLE_BRANCH_ANY;
45 
46 	cpu_cnt = libbpf_num_possible_cpus();
47 	pfd_array = malloc(sizeof(int) * cpu_cnt);
48 	if (!pfd_array) {
49 		cpu_cnt = 0;
50 		return 1;
51 	}
52 
53 	for (cpu = 0; cpu < cpu_cnt; cpu++) {
54 		pfd_array[cpu] = syscall(__NR_perf_event_open, &attr,
55 					 -1, cpu, -1, PERF_FLAG_FD_CLOEXEC);
56 		if (pfd_array[cpu] < 0)
57 			break;
58 	}
59 
60 	return cpu == 0;
61 }
62 
63 static void close_perf_events(void)
64 {
65 	int cpu, fd;
66 
67 	for (cpu = 0; cpu < cpu_cnt; cpu++) {
68 		fd = pfd_array[cpu];
69 		if (fd < 0)
70 			break;
71 		close(fd);
72 	}
73 	free(pfd_array);
74 }
75 
76 void serial_test_get_branch_snapshot(void)
77 {
78 	struct get_branch_snapshot *skel = NULL;
79 	int err;
80 
81 	/* Skip the test before we fix LBR snapshot for hypervisor. */
82 	if (is_hypervisor()) {
83 		test__skip();
84 		return;
85 	}
86 
87 	if (create_perf_events()) {
88 		test__skip();  /* system doesn't support LBR */
89 		goto cleanup;
90 	}
91 
92 	skel = get_branch_snapshot__open_and_load();
93 	if (!ASSERT_OK_PTR(skel, "get_branch_snapshot__open_and_load"))
94 		goto cleanup;
95 
96 	err = kallsyms_find("bpf_testmod_loop_test", &skel->bss->address_low);
97 	if (!ASSERT_OK(err, "kallsyms_find"))
98 		goto cleanup;
99 
100 	/* Just a guess for the end of this function, as module functions
101 	 * in /proc/kallsyms could come in any order.
102 	 */
103 	skel->bss->address_high = skel->bss->address_low + 128;
104 
105 	err = get_branch_snapshot__attach(skel);
106 	if (!ASSERT_OK(err, "get_branch_snapshot__attach"))
107 		goto cleanup;
108 
109 	trigger_module_test_read(100);
110 
111 	if (skel->bss->total_entries < 16) {
112 		/* too few entries for the hit/waste test */
113 		test__skip();
114 		goto cleanup;
115 	}
116 
117 	ASSERT_GT(skel->bss->test1_hits, 6, "find_looptest_in_lbr");
118 
119 	/* Given we stop LBR in software, we will waste a few entries.
120 	 * But we should try to waste as few as possible entries. We are at
121 	 * about 7 on x86_64 systems.
122 	 * Add a check for < 10 so that we get heads-up when something
123 	 * changes and wastes too many entries.
124 	 */
125 	ASSERT_LT(skel->bss->wasted_entries, 10, "check_wasted_entries");
126 
127 cleanup:
128 	get_branch_snapshot__destroy(skel);
129 	close_perf_events();
130 }
131