[hppa-linux] Picky details of TLB fault handlers

[Alan Cox]

> HP-UX does exactly this sort of thing for handling many traps and
> interrupts.  It is fairly expensive, though, since you have to have
> a stack on which to save the IPSW/IIAQ and probably a bunch of other
> registers, and it's too much messing around for a TLB miss.

I'm right in assuming its legal to swap the return address - so the TLB
handler can do a short piece of TLB handling for a present page miss,
then stash the return into the kernel stack and rfi into the page fault handler
so it will in turn return to the user context ?

Alan