This may be a waste of time for OpenBSD and way too specific in application (64-bit etc.) but as I don't have the knowledge to say and in case it is useful, here's the presentation.
It uses unused bits to create an auth tag for pointers which are apparently atleast 3 bits but 16 bits on Linux. Apparently there should be a paper around that may be faster to assess. Raising the Bar: New Hardware Primitives for Exploit Mitigations (ARM v8 - Qualcomm) https://www.youtube.com/watch?v=PYe8W33lbAQ
