xref: /openbmc/linux/samples/bpf/syscall_tp_user.c (revision de4825a4)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (c) 2017 Facebook
3  */
4 #include <stdio.h>
5 #include <unistd.h>
6 #include <fcntl.h>
7 #include <stdlib.h>
8 #include <string.h>
9 #include <linux/perf_event.h>
10 #include <errno.h>
11 #include <bpf/libbpf.h>
12 #include <bpf/bpf.h>
13 
14 /* This program verifies bpf attachment to tracepoint sys_enter_* and sys_exit_*.
15  * This requires kernel CONFIG_FTRACE_SYSCALLS to be set.
16  */
17 
usage(const char * cmd)18 static void usage(const char *cmd)
19 {
20 	printf("USAGE: %s [-i nr_tests] [-h]\n", cmd);
21 	printf("       -i nr_tests      # rounds of test to run\n");
22 	printf("       -h               # help\n");
23 }
24 
verify_map(int map_id)25 static void verify_map(int map_id)
26 {
27 	__u32 key = 0;
28 	__u32 val;
29 
30 	if (bpf_map_lookup_elem(map_id, &key, &val) != 0) {
31 		fprintf(stderr, "map_lookup failed: %s\n", strerror(errno));
32 		return;
33 	}
34 	if (val == 0) {
35 		fprintf(stderr, "failed: map #%d returns value 0\n", map_id);
36 		return;
37 	}
38 
39 	printf("verify map:%d val: %d\n", map_id, val);
40 
41 	val = 0;
42 	if (bpf_map_update_elem(map_id, &key, &val, BPF_ANY) != 0) {
43 		fprintf(stderr, "map_update failed: %s\n", strerror(errno));
44 		return;
45 	}
46 }
47 
test(char * filename,int nr_tests)48 static int test(char *filename, int nr_tests)
49 {
50 	int map0_fds[nr_tests], map1_fds[nr_tests], fd, i, j = 0;
51 	struct bpf_link **links = NULL;
52 	struct bpf_object *objs[nr_tests];
53 	struct bpf_program *prog;
54 
55 	for (i = 0; i < nr_tests; i++) {
56 		objs[i] = bpf_object__open_file(filename, NULL);
57 		if (libbpf_get_error(objs[i])) {
58 			fprintf(stderr, "opening BPF object file failed\n");
59 			objs[i] = NULL;
60 			goto cleanup;
61 		}
62 
63 		/* One-time initialization */
64 		if (!links) {
65 			int nr_progs = 0;
66 
67 			bpf_object__for_each_program(prog, objs[i])
68 				nr_progs += 1;
69 
70 			links = calloc(nr_progs * nr_tests, sizeof(struct bpf_link *));
71 
72 			if (!links)
73 				goto cleanup;
74 		}
75 
76 		/* load BPF program */
77 		if (bpf_object__load(objs[i])) {
78 			fprintf(stderr, "loading BPF object file failed\n");
79 			goto cleanup;
80 		}
81 
82 		map0_fds[i] = bpf_object__find_map_fd_by_name(objs[i],
83 							      "enter_open_map");
84 		map1_fds[i] = bpf_object__find_map_fd_by_name(objs[i],
85 							      "exit_open_map");
86 		if (map0_fds[i] < 0 || map1_fds[i] < 0) {
87 			fprintf(stderr, "finding a map in obj file failed\n");
88 			goto cleanup;
89 		}
90 
91 		bpf_object__for_each_program(prog, objs[i]) {
92 			links[j] = bpf_program__attach(prog);
93 			if (libbpf_get_error(links[j])) {
94 				fprintf(stderr, "bpf_program__attach failed\n");
95 				links[j] = NULL;
96 				goto cleanup;
97 			}
98 			j++;
99 		}
100 		printf("prog #%d: map ids %d %d\n", i, map0_fds[i], map1_fds[i]);
101 	}
102 
103 	/* current load_bpf_file has perf_event_open default pid = -1
104 	 * and cpu = 0, which permits attached bpf execution on
105 	 * all cpus for all pid's. bpf program execution ignores
106 	 * cpu affinity.
107 	 */
108 	/* trigger some "open" operations */
109 	fd = open(filename, O_RDONLY);
110 	if (fd < 0) {
111 		fprintf(stderr, "open failed: %s\n", strerror(errno));
112 		return 1;
113 	}
114 	close(fd);
115 
116 	/* verify the map */
117 	for (i = 0; i < nr_tests; i++) {
118 		verify_map(map0_fds[i]);
119 		verify_map(map1_fds[i]);
120 	}
121 
122 cleanup:
123 	if (links) {
124 		for (j--; j >= 0; j--)
125 			bpf_link__destroy(links[j]);
126 
127 		free(links);
128 	}
129 
130 	for (i--; i >= 0; i--)
131 		bpf_object__close(objs[i]);
132 	return 0;
133 }
134 
main(int argc,char ** argv)135 int main(int argc, char **argv)
136 {
137 	int opt, nr_tests = 1;
138 	char filename[256];
139 
140 	while ((opt = getopt(argc, argv, "i:h")) != -1) {
141 		switch (opt) {
142 		case 'i':
143 			nr_tests = atoi(optarg);
144 			break;
145 		case 'h':
146 		default:
147 			usage(argv[0]);
148 			return 0;
149 		}
150 	}
151 
152 	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
153 
154 	return test(filename, nr_tests);
155 }
156