[PATCH v9 26/39] arm64: Add Kconfig for Guarded Control Stack (GCS)

[Mark Brown]

Provide a Kconfig option allowing the user to select if GCS support is
built into the kernel.

Reviewed-by: Thiago Jung Bauermann <thiago.bauermann at linaro.org>
Signed-off-by: Mark Brown <broonie at kernel.org>
---
 arch/arm64/Kconfig | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 5d91259ee7b5..248697a29d78 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -2140,6 +2140,26 @@ 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"
+
 config ARM64_SVE
 	bool "ARM Scalable Vector Extension support"
 	default y

-- 
2.39.2