Not all 64-bit Book-3E parts will have fixed IVORs so add a function that
cpusetup code can call to setup the base IVORs (0..15) to match the fixed
offsets.  We need to 'or' part of interrupt_base_book3e into the IVORs
since on parts that have them the IVPR doesn't extend as far down.
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Match what we do on 32-bit Book-E processors and enable the decrementer
in generic_calibrate_decr.  We need to make sure we disable the
decrementer early in boot since we currently use lazy (soft) interrupt
on 64-bit Book-E and possible get a decrementer exception before we
are ready for it.
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This contains all the bits that didn't fit in previous patches :-) This
includes the actual exception handlers assembly, the changes to the
kernel entry, other misc bits and wiring it all up in Kconfig.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>