system tap @cast example

gistfile1.txt

function string_ops:string (val) %{
  strlcpy (STAP_RETVALUE, (char*)STAP_ARG_val, MAXSTRINGLEN);
%}

probe kernel.function("udp_gro_receive") {
    if (cpu() == 0) {
        printf("udp_gro_receive %d %s(%d/%d) %s %d, %d, %d\n", gettimeofday_us(), execname(), pid(), cpu(), $$vars, $skb->ip_summed, @cast($skb->cb, "struct napi_gro_cb")->csum_cnt, @cast($skb->cb, "struct napi_gro_cb")->csum_valid);
        print_backtrace();
    }
}