K 10
svn:author
V 6
andrew
K 8
svn:date
V 27
2017-04-12T16:28:40.367891Z
K 7
svn:log
V 482
Start to use the User and Privileged execute-never bits in the arm64
pagetables. This sets both bits when entering an address we know shouldn't
be executed.

I expect we could mark all userspace pages as Privileged execute-never to
ensure the kernel doesn't branch to one of these addresses.

While here add the ARMv8.1 upper attributes.

Reviewed by:	alc, kib (previous version)
MFC after:	1 week
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D10360

END