sparc64: fix for user probes in high memory

sparc64: fix for user probes in high memory

When returning from the user probe code into userspace process, PC & NPC are
truncated to 32 bits.

Due to shared libraries getting loaded very high in the virtual address
space of
the process, placing a user probe inside a shared library makes the kernel
return into the process at the wrong address, causing it to seg'fault
most of
the time.

This patch prevents truncating PC and NPC.

Signed-off-by: Eric Saint Etienne <eric.saint.etienne@oracle.com>
Reviewed-by: David Aldridge <david.j.aldridge@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>