samples, bpf: Refactor kprobe tracing user progs with libbpf
Currently, the kprobe BPF program attachment method for bpf_load is
quite old. The implementation of bpf_load "directly" controls and
manages(create, delete) the kprobe events of DEBUGFS. On the other hand,
using using the libbpf automatically manages the kprobe event.
(under bpf_link interface)
By calling bpf_program__attach(_kprobe) in libbpf, the corresponding
kprobe is created and the BPF program will be attached to this kprobe.
To remove this, by simply invoking bpf_link__destroy will clean up the
event.
This commit refactors kprobe tracing programs (tracex{1~7}_user.c) with
libbpf using bpf_link interface and bpf_program__attach.
tracex2_kern.c, which tracks system calls (sys_*), has been modified to
append prefix depending on architecture.
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200516040608.1377876-3-danieltimlee@gmail.com
diff --git a/samples/bpf/tracex3_user.c b/samples/bpf/tracex3_user.c
index cf8fedc..70e9877 100644
--- a/samples/bpf/tracex3_user.c
+++ b/samples/bpf/tracex3_user.c
@@ -7,11 +7,10 @@
#include <unistd.h>
#include <stdbool.h>
#include <string.h>
-#include <linux/bpf.h>
#include <sys/resource.h>
#include <bpf/bpf.h>
-#include "bpf_load.h"
+#include <bpf/libbpf.h>
#include "bpf_util.h"
#define SLOTS 100
@@ -109,20 +108,11 @@ static void print_hist(int fd)
int main(int ac, char **argv)
{
struct rlimit r = {1024*1024, RLIM_INFINITY};
+ struct bpf_link *links[2];
+ struct bpf_program *prog;
+ struct bpf_object *obj;
char filename[256];
- int i;
-
- snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
-
- if (setrlimit(RLIMIT_MEMLOCK, &r)) {
- perror("setrlimit(RLIMIT_MEMLOCK)");
- return 1;
- }
-
- if (load_bpf_file(filename)) {
- printf("%s", bpf_log_buf);
- return 1;
- }
+ int map_fd, i, j = 0;
for (i = 1; i < ac; i++) {
if (strcmp(argv[i], "-a") == 0) {
@@ -137,6 +127,40 @@ int main(int ac, char **argv)
}
}
+ if (setrlimit(RLIMIT_MEMLOCK, &r)) {
+ perror("setrlimit(RLIMIT_MEMLOCK)");
+ return 1;
+ }
+
+ 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;
+ }
+
+ /* 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, "lat_map");
+ 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[j] = bpf_program__attach(prog);
+ if (libbpf_get_error(links[j])) {
+ fprintf(stderr, "ERROR: bpf_program__attach failed\n");
+ links[j] = NULL;
+ goto cleanup;
+ }
+ j++;
+ }
+
printf(" heatmap of IO latency\n");
if (text_only)
printf(" %s", sym[num_colors - 1]);
@@ -153,9 +177,14 @@ int main(int ac, char **argv)
for (i = 0; ; i++) {
if (i % 20 == 0)
print_banner();
- print_hist(map_fd[1]);
+ print_hist(map_fd);
sleep(2);
}
+cleanup:
+ for (j--; j >= 0; j--)
+ bpf_link__destroy(links[j]);
+
+ bpf_object__close(obj);
return 0;
}