ARM atomic question

[Mark Tinguely]

>  Right.  The kernel checks to see if a RAS is in flight.  If so, it
>  restores the pc to the start of the RAS.
>
>  Warner

Thank-you, I found it in the PUSHFRAMEINSVC definition. That was the piece
of the puzzle that I was missing, sorry for the noise. 

Thank-you to Grzegorz Bernacki for doing testing on the cache coherency
problem when the kernel mapped page is shared. He gave me insight to the
fact that a shared  kernel mapped page can be removed via pmap_remove_all().

--Mark.