[PATCH} PPC64: revised patch for recursive xmon entry

[Paul Mackerras]

Linas Vepstas writes:

> I had a recursive call to xmon in linux-2.6.10-rc2 after a crash 
> to firmware.  The resursion was due to a scrambled value in r1 
> inherited from firmware.  The following patch prevents the recursion
> and sets up a usable stack. Unfortunately, it still doesn't get us
> to an xmon prompt; xmon thinks some other cpu is in control.  
> I'll see if I can fix that next, if I manage to reproduce.

I don't think this is the right approach; we should be detecting the
bogus stack pointer and switching to the emergency stack in the
exception entry code.  By the time we get to your stack we would have
already been using the bogus stack for some time.

Paul.