patch out kernel retpoline (marc.info)
from tedu@azorius.net to openbsd@azorius.net on 07 Aug 2023 11:44
https://azorius.net/g/openbsd/p/DSTh7v9F4cp1s8q6V5-patch-out-retpoline

Changes by: guenther@cvs.openbsd.org

On CPUs with eIBRS ("enhanced Indirect Branch Restricted Speculation") or IBT enabled the kernel, the hardware should (not have) the attacks which retpolines were created to prevent. In those cases, retpolines should be a net negative for security as they are an indirect branch gadget. They're also slower.

Commit: https://github.com/openbsd/src/commit/1538f8cb209f93ed99ddae606a02707e3bdd9dfc

#openbsd #security