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

Catalin Marinas
2024-08-22T08:59:04Z

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@linaro.org>
> Signed-off-by: Mark Brown <broonie@kernel.org>

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