Since interrupt stacks were split, current sits in the prefix page. Did anyone think about returning it into a register? I am not sufficiently familiar with the architecture to figure it out. Candidates include control 10 (PER start), control 15 (Linkage), and GPR 12. Possibly I missed something.
I was thinking about abusing X15, but it seems that applications may do some mischief trying "extract saved registers" instructions. PER appears to be used, I am not sure if that's actually the case. So, I am zooming on R12. Anyone wants to comment? -- Pete
