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/trace_output_user.c b/samples/bpf/trace_output_user.c
index 60a17dd..364b987 100644
--- a/samples/bpf/trace_output_user.c
+++ b/samples/bpf/trace_output_user.c
@@ -1,23 +1,10 @@
// SPDX-License-Identifier: GPL-2.0-only
#include <stdio.h>
-#include <unistd.h>
-#include <stdlib.h>
-#include <stdbool.h>
-#include <string.h>
#include <fcntl.h>
#include <poll.h>
-#include <linux/perf_event.h>
-#include <linux/bpf.h>
-#include <errno.h>
-#include <assert.h>
-#include <sys/syscall.h>
-#include <sys/ioctl.h>
-#include <sys/mman.h>
#include <time.h>
#include <signal.h>
#include <bpf/libbpf.h>
-#include "bpf_load.h"
-#include "perf-sys.h"
static __u64 time_get_ns(void)
{
@@ -57,20 +44,48 @@ static void print_bpf_output(void *ctx, int cpu, void *data, __u32 size)
int main(int argc, char **argv)
{
struct perf_buffer_opts pb_opts = {};
+ struct bpf_link *link = NULL;
+ struct bpf_program *prog;
struct perf_buffer *pb;
+ struct bpf_object *obj;
+ int map_fd, ret = 0;
char filename[256];
FILE *f;
- int ret;
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_map");
+ if (map_fd < 0) {
+ fprintf(stderr, "ERROR: finding a map in obj file failed\n");
+ goto cleanup;
+ }
+
+ prog = bpf_object__find_program_by_name(obj, "bpf_prog1");
+ if (libbpf_get_error(prog)) {
+ fprintf(stderr, "ERROR: finding a prog in obj file failed\n");
+ goto cleanup;
+ }
+
+ link = bpf_program__attach(prog);
+ if (libbpf_get_error(link)) {
+ fprintf(stderr, "ERROR: bpf_program__attach failed\n");
+ link = NULL;
+ goto cleanup;
}
pb_opts.sample_cb = print_bpf_output;
- pb = perf_buffer__new(map_fd[0], 8, &pb_opts);
+ pb = perf_buffer__new(map_fd, 8, &pb_opts);
ret = libbpf_get_error(pb);
if (ret) {
printf("failed to setup perf_buffer: %d\n", ret);
@@ -84,5 +99,9 @@ int main(int argc, char **argv)
while ((ret = perf_buffer__poll(pb, 1000)) >= 0 && cnt < MAX_CNT) {
}
kill(0, SIGINT);
+
+cleanup:
+ bpf_link__destroy(link);
+ bpf_object__close(obj);
return ret;
}