5.8. Prefetch Abort handler
If the system has no MMU, the Prefetch Abort handler can simply
report the error and quit. Otherwise the address that caused the
abort must be restored into physical memory. lr_ABT points
to the instruction at the address following the one that caused
the abort, so the address to be restored is at lr_ABT -
4. The virtual memory fault for that address can be dealt
with and the instruction fetch retried. The handler should therefore
return to the same instruction rather than the following one, for
example:
SUBS pc,lr,#4