GitLab

Some iOS devices enable pointer authentication, which uses the
higher-order bits of pointers to store a signature. This CL strips the
signature off of frame pointers before attempting to compute a module
offset.

The iOS documentation recommends using the ptrauth_strip() macro, but
for now we will simply use a static mask.

BUG=1084257

Change-Id: I760056a00cb698b3efd5370149b5b1ea77a199a8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2207961
Commit-Queue: Rohit Rao <rohitrao@chromium.org>
Reviewed-by: Erik Chen <erikchen@chromium.org>
Reviewed-by: Mike Wittman <wittman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#769897}