Re: [PATCH v11 27/39] arm64: Add Kconfig for Guarded Control Stack (GCS)

On Thu, Aug 22, 2024 at 02:15:30AM +0100, Mark Brown wrote:

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index a2f8ff354ca6..772f9ba99fe8 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -2137,6 +2137,26 @@ config ARM64_EPAN if the cpu does not implement the feature. endmenu # "ARMv8.7 architectural features" +menu "v9.4 architectural features"

+config ARM64_GCS

• bool "Enable support for Guarded Control Stack (GCS)"
• default y
• select ARCH_HAS_USER_SHADOW_STACK
• select ARCH_USES_HIGH_VMA_FLAGS
• help

•  Guarded Control Stack (GCS) provides support for a separate
  

•  stack with restricted access which contains only return
  

•  addresses.  This can be used to harden against some attacks
  

•  by comparing return address used by the program with what is
  

•  stored in the GCS, and may also be used to efficiently obtain
  

•  the call stack for applications such as profiling.
  

•  The feature is detected at runtime, and will remain disabled
  

•  if the system does not implement the feature.
  

+endmenu # "v9.4 architectural features"

BTW, as Mark R spotted we'd also need to handle uprobes. Since that's off in defconfig, I think it can be done separately on top of this series. In the meantime, we could make this dependent on !UPROBES.