kallsyms_find
err = kallsyms_find("bpf_testmod_loop_test", &skel->bss->address_low);
err = kallsyms_find("bpf_link_fops", &link_fops_addr);
err = kallsyms_find("__per_cpu_start", &per_cpu_start_addr);
err = kallsyms_find("runqueues", &runqueues_addr);
err = kallsyms_find("bpf_prog_active", &bpf_prog_active_addr);
int kallsyms_find(const char *sym, unsigned long long *addr);