[$] Some near-term arm64 hardening patches

The arm64 architecture is found at the core of many, if not most, mobile
devices; that means that arm64 devices are destined to be the target of
attackers worldwide. That has led to a high level of interest in
technologies that can harden these systems. There are currently several
such technologies, based in both hardware and software, that are being
readied for the arm64 kernel; read on for a survey on what is
coming.