attach_usdt
static int attach_usdt(const struct bpf_program *prog, long cookie, struct bpf_link **link);
SEC_DEF("usdt+", KPROBE, 0, SEC_USDT, attach_usdt),
SEC_DEF("usdt.s+", KPROBE, 0, SEC_USDT | SEC_SLEEPABLE, attach_usdt),