On Sat, Mar 02, 2024 at 03:57:02PM +0100, Szabolcs Nagy wrote: > * Mark Brown <broonie@xxxxxxxxxx> [2024-02-21 17:36:12 +0000]: > > > I said NOP but there's no reason it strictly needs to be a NOP. It > > > could instead do something reasonable to convey the state of racing > > > with shadow stack being disabled. > > This feels like it's getting complicated and I fear it may be an uphill > > struggle to get such code merged, at least for arm64. My instinct is > the aarch64 behaviour is already nop > for gcs instructions when gcs is disabled. > the isa was designed so async disable is > possible. Yeah, we'd need to handle GCSPR_EL0 somehow (currently it's inaccessible when GCS is disabled) and userspace would need to take care it's not doing something that could get stuck if for example a pop didn't actually *do* anything.
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