[patch/hppa-linux] MD_FALLBACK_FRAME_STATE_FOR definition

[Randolph Chung]

> You'll need a PC adjustment for boundary cases.  It's quite possible
> that you haven't yet seen a test case that fails.  (Unless hppa leaves
> PC pointing at the insn after the one that traps, in which case you
> may ignore this advice.)

do you have a specific test case for me? :) or point me to the bit of
code that uses this "adjusted PC"?

there are several things:
- on palinux, the "PC" (iaoq[0]) has the 2 lower bits set for userspace
  addresses, so if the fault occured in 0x10780, the iaoq[0] in the
  sigcontext will have 0x10783. (instructions are all 4-bytes wide, so
  the next insn will usually be at 0x10784)

- pa has a two-level deep "PC", so there's an iaoq[0] and iaoq[1].
  iaoq[1] points to the next insn to be executed. in some cases this is
  not iaoq[0]+4 (for some branching cases).

so... i need to know how this is used to know if/how we need to adjust
the PC.

i'll update the patch for hppa-signals.h.

thanks
randolph