From your code I'm inferring that the halfwords following the RP instruction give the offsets from the address in R15 to the values for updating the PSW, general register and access register, depending on the bit settings, of course.
In your example the contents of R15 would be replaced by whatever's in XTRAP_GREG+15*4. In my dump R15 is zero which, if I'm right about how the instruction works, is not an error. I'll have to see if I can find R15's original value to make sure everything is consistent. Thank you very much for your example. It helped me eliminate a lot of red herrings.
