This function will only ever get called when stopped at the entry or exit
of a syscall, so by checking for 0 in x0 (arg0/retval), x1 (arg1), x8
(syscall), x29 (FP) and x30 (LR) we can infer:
- 1) Either inferior is at exit from sucessful execve.
+ 1) Either inferior is at exit from successful execve.
2) Or inferior is at entry to a call to io_setup with invalid arguments and
a corrupted FP and LR.
It should be safe enough to assume case 1. */