On Fault then ARM will return information about the fault in ESR_EL1 to
the user.
We need to decode what ESR_EL1 means in the context of the fault to get
the flags we care about.
The flags we care about specifically are PF_USER and PF_WRITE.
PF_PROT would have been interesting but I didn't see when this gets
returned to the user. ARM makes the difference if the page is unmapped
or "mapped" with PROT_NONE. x86 doesn't make the distinction here.
This should fix an issue that a user was hitting.
Ryan Houdek
82ad26307c