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samples: bpf: Refactor kprobe tracing programs with libbpf

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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
This commit is contained in:
Daniel T. Lee
2020-08-23 17:53:33 +09:00
committed by Alexei Starovoitov
parent 35a8b6dd33
commit 3677d0a131
11 changed files with 272 additions and 118 deletions
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42
samples/bpf/lathist_user.c
View File

@@ -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;
}