Re: [PATCH v11 05/39] arm64: Document boot requirements for Guarded Control Stacks

[Catalin Marinas]

On Thu, Aug 22, 2024 at 02:15:08AM +0100, Mark Brown wrote:
> FEAT_GCS introduces a number of new system registers, we require that
> access to these registers is not trapped when we identify that the feature
> is present.  There is also a HCRX_EL2 control to make GCS operations
> functional.
> 
> Since if GCS is enabled any function call instruction will cause a fault
> we also require that the feature be specifically disabled, existing
> kernels implicitly have this requirement and especially given that the
> MMU must be disabled it is difficult to see a situation where leaving
> GCS enabled would be reasonable.
> 
> Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@xxxxxxxxxx>
> Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>

Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>