cpc Probe Arguments

The arguments to cpc probes are the following:

arg0

The program counter (PC) in the kernel at the time that the probe fired, or 0 if the current process was not executing in the kernel at the time that the probe fired

arg1

The PC in the user-level process at the time that the probe fired, or 0 if the current process was executing at the kernel at the time that the probe fired

As the descriptions imply, if arg0 is non-zero then arg1 is zero; if arg0 is zero then arg1 is non-zero.