tree a34a6ae5f26cc14fd46b2d52d07078163bcc25de
parent b97cfb2f8abc224fc29095fd9280700ae4233112
author Peter Collingbourne <pcc@google.com> 1606336346 -0800
committer Peter Collingbourne <pcc@google.com> 1606343953 -0800

darwin-aarch64: Implement JIT support in TCG

Apple CPUs implement W^X on JITed pages with a fast userspace
switch between W and X, as explained here:
https://developer.apple.com/documentation/apple_silicon/porting_just-in-time_compilers_to_apple_silicon

It seems like the simplest approach to making this work with TCG is to
tie enabling and disabling write protection to the TB lock, so that is
what this patch implements.

Change-Id: Ie56526cfc2412c9ac5341343068a1cf454b10213