samples/bpf/syscall_tp_user.c

Source file repositories/reference/linux-study-clean/samples/bpf/syscall_tp_user.c

File Facts

System
Linux kernel
Corpus path
samples/bpf/syscall_tp_user.c
Extension
.c
Size
3522 bytes
Lines
156
Domain
Support Tooling And Documentation
Bucket
samples
Inferred role
Support Tooling And Documentation: syscall or user/kernel boundary
Status
core implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

if (libbpf_get_error(objs[i])) {
			fprintf(stderr, "opening BPF object file failed\n");
			objs[i] = NULL;
			goto cleanup;
		}

		/* One-time initialization */
		if (!links) {
			int nr_progs = 0;

			bpf_object__for_each_program(prog, objs[i])
				nr_progs += 1;

			links = calloc(nr_progs * nr_tests, sizeof(struct bpf_link *));

			if (!links)
				goto cleanup;
		}

		/* load BPF program */
		if (bpf_object__load(objs[i])) {
			fprintf(stderr, "loading BPF object file failed\n");
			goto cleanup;
		}

		map0_fds[i] = bpf_object__find_map_fd_by_name(objs[i],
							      "enter_open_map");
		map1_fds[i] = bpf_object__find_map_fd_by_name(objs[i],
							      "exit_open_map");
		if (map0_fds[i] < 0 || map1_fds[i] < 0) {
			fprintf(stderr, "finding a map in obj file failed\n");
			goto cleanup;
		}

		bpf_object__for_each_program(prog, objs[i]) {
			links[j] = bpf_program__attach(prog);
			if (libbpf_get_error(links[j])) {
				fprintf(stderr, "bpf_program__attach failed\n");
				links[j] = NULL;
				goto cleanup;
			}
			j++;
		}
		printf("prog #%d: map ids %d %d\n", i, map0_fds[i], map1_fds[i]);
	}

	/* current load_bpf_file has perf_event_open default pid = -1
	 * and cpu = 0, which permits attached bpf execution on
	 * all cpus for all pid's. bpf program execution ignores
	 * cpu affinity.
	 */
	/* trigger some "open" operations */
	fd = open(filename, O_RDONLY);
	if (fd < 0) {
		fprintf(stderr, "open failed: %s\n", strerror(errno));
		return 1;
	}
	close(fd);

	/* verify the map */
	for (i = 0; i < nr_tests; i++) {
		verify_map(map0_fds[i]);
		verify_map(map1_fds[i]);
	}

cleanup:
	if (links) {
		for (j--; j >= 0; j--)
			bpf_link__destroy(links[j]);

		free(links);
	}

	for (i--; i >= 0; i--)
		bpf_object__close(objs[i]);
	return 0;
}

int main(int argc, char **argv)
{
	int opt, nr_tests = 1;
	char filename[256];

	while ((opt = getopt(argc, argv, "i:h")) != -1) {
		switch (opt) {
		case 'i':
			nr_tests = atoi(optarg);
			break;
		case 'h':
		default:

Annotation

Implementation Notes