lib/powerpc: Add generic decrementer exception handler

Add the lib/powerpc/handlers.c file and associated header files as a place
to implement generic exception handler functions for inclusion in tests.

Add a generic exception handler for a decrementer (0x900) interrupt which
will reset the decrementer to its maximum value.

Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
4 files changed