/* * Figure out the next frame up in the call stack. * For trap(), we print the address of the faulting instruction and * proceed with the calling frame. We return the ip that faulted. * If the trap was caused by jumping through a bogus pointer, then * the next line in the backtrace will list some random function as * being called. It should get the argument list correct, though. * It might be possible to dig out from the next frame up the name * of the function that faulted, but that could get hairy. */