On Mon, 20 Feb 2023 at 16:53, Mark Brown <broonie@xxxxxxxxxx> wrote: > > On Wed, Feb 08, 2023 at 03:36:40PM +0100, Ard Biesheuvel wrote: > > > OTOH, what is the penalty for setting the GP attribute and using the > > translation table on a core that does not implement BTI? > > The concern with doing that for Linux was what would happen if someone > implemented a system with mixed BTI/no BTI support and then a task got > preempted and moved between the two, you might end up with PSTATE.BTYPE > incorrectly set and trigger a spurious fault. That shouldn't be an > issue for EFI runtime services. Right, I hadn't figured that. But as you say, this shouldn't affect EFI runtime services, as they are non-preemptible and therefore non-migratable.
