This implements CONFIG_PREEMPT for ppc64.  Aside from the entry.S
changes to check the _TIF_NEED_RESCHED bit when returning from an
exception, there are various changes to make the ppc64-specific code
preempt-safe, mostly adding preempt_enable/disable or get_cpu/put_cpu
calls where needed.  I have been using this on my desktop G5 for the
last week without problems.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>