samples: bpf: Refactor kprobe tracing programs with libbpf
For the problem of increasing fragmentation of the bpf loader programs,
instead of using bpf_loader.o, which is used in samples/bpf, this
commit refactors the existing kprobe tracing programs with libbbpf
bpf loader.
- For kprobe events pointing to system calls, the SYSCALL() macro in
trace_common.h was used.
- Adding a kprobe event and attaching a bpf program to it was done
through bpf_program_attach().
- Instead of using the existing BPF MAP definition, MAP definition
has been refactored with the new BTF-defined MAP format.
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200823085334.9413-3-danieltimlee@gmail.com
diff --git a/samples/bpf/lathist_user.c b/samples/bpf/lathist_user.c
index 2ff2839..7d8ff24 100644
--- a/samples/bpf/lathist_user.c
+++ b/samples/bpf/lathist_user.c
@@ -6,9 +6,8 @@
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
-#include <linux/bpf.h>
+#include <bpf/libbpf.h>
#include <bpf/bpf.h>
-#include "bpf_load.h"
#define MAX_ENTRIES 20
#define MAX_CPU 4
@@ -81,20 +80,51 @@ static void get_data(int fd)
int main(int argc, char **argv)
{
+ struct bpf_link *links[2];
+ struct bpf_program *prog;
+ struct bpf_object *obj;
char filename[256];
+ int map_fd, i = 0;
snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+ obj = bpf_object__open_file(filename, NULL);
+ if (libbpf_get_error(obj)) {
+ fprintf(stderr, "ERROR: opening BPF object file failed\n");
+ return 0;
+ }
- if (load_bpf_file(filename)) {
- printf("%s", bpf_log_buf);
- return 1;
+ /* load BPF program */
+ if (bpf_object__load(obj)) {
+ fprintf(stderr, "ERROR: loading BPF object file failed\n");
+ goto cleanup;
+ }
+
+ map_fd = bpf_object__find_map_fd_by_name(obj, "my_lat");
+ if (map_fd < 0) {
+ fprintf(stderr, "ERROR: finding a map in obj file failed\n");
+ goto cleanup;
+ }
+
+ bpf_object__for_each_program(prog, obj) {
+ links[i] = bpf_program__attach(prog);
+ if (libbpf_get_error(links[i])) {
+ fprintf(stderr, "ERROR: bpf_program__attach failed\n");
+ links[i] = NULL;
+ goto cleanup;
+ }
+ i++;
}
while (1) {
- get_data(map_fd[1]);
+ get_data(map_fd);
print_hist();
sleep(5);
}
+cleanup:
+ for (i--; i >= 0; i--)
+ bpf_link__destroy(links[i]);
+
+ bpf_object__close(obj);
return 0;
}