Occasionally the ppc64 kernel emulates a usermode instruction, for
example in the alignment exception handler.  Kumar Gala pointed out
(in the context of the ppc32 kernel) that if the instruction was being
single-stepped, and we end up emulating the instruction, we should
then send the process a SIGTRAP as if it had not been emulated and the
process had then taken a single-step exception.  This patch implements
this for ppc64.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>