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
is_hypervisor(void)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
create_perf_events(void)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
close_perf_events(void)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
serial_test_get_branch_snapshot(void)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