linux/samples/bpf/trace_output_user.c
Daniel T. Lee 3677d0a131 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
2020-08-24 20:59:35 -07:00

108 lines
2.3 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
#include <stdio.h>
#include <fcntl.h>
#include <poll.h>
#include <time.h>
#include <signal.h>
#include <bpf/libbpf.h>
static __u64 time_get_ns(void)
{
struct timespec ts;
clock_gettime(CLOCK_MONOTONIC, &ts);
return ts.tv_sec * 1000000000ull + ts.tv_nsec;
}
static __u64 start_time;
static __u64 cnt;
#define MAX_CNT 100000ll
static void print_bpf_output(void *ctx, int cpu, void *data, __u32 size)
{
struct {
__u64 pid;
__u64 cookie;
} *e = data;
if (e->cookie != 0x12345678) {
printf("BUG pid %llx cookie %llx sized %d\n",
e->pid, e->cookie, size);
return;
}
cnt++;
if (cnt == MAX_CNT) {
printf("recv %lld events per sec\n",
MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
return;
}
}
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;
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, "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, 8, &pb_opts);
ret = libbpf_get_error(pb);
if (ret) {
printf("failed to setup perf_buffer: %d\n", ret);
return 1;
}
f = popen("taskset 1 dd if=/dev/zero of=/dev/null", "r");
(void) f;
start_time = time_get_ns();
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;
}