Commit ce0641d4 authored by Mark Brown's avatar Mark Brown Committed by Catalin Marinas
Browse files

arm64/sysreg: Add definitions for architected GCS caps 



The architecture defines a format for guarded control stack caps, used
to mark the top of an unused GCS in order to limit the potential for
exploitation via stack switching. Add definitions associated with these.

Reviewed-by: default avatarThiago Jung Bauermann <thiago.bauermann@linaro.org>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20241001-arm64-gcs-v13-8-222b78d87eee@kernel.org


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 7058bf87

arch/arm64/include/asm/sysreg.h

+20 −0
Original line number Diff line number Diff line
@@ -1101,6 +1101,26 @@ 
/* Initial value for Permission Overlay Extension for EL0 */

#define POR_EL0_INIT	POE_RXW



/*

 * Definitions for Guarded Control Stack

 */



#define GCS_CAP_ADDR_MASK		GENMASK(63, 12)

#define GCS_CAP_ADDR_SHIFT		12

#define GCS_CAP_ADDR_WIDTH		52

#define GCS_CAP_ADDR(x)			FIELD_GET(GCS_CAP_ADDR_MASK, x)



#define GCS_CAP_TOKEN_MASK		GENMASK(11, 0)

#define GCS_CAP_TOKEN_SHIFT		0

#define GCS_CAP_TOKEN_WIDTH		12

#define GCS_CAP_TOKEN(x)		FIELD_GET(GCS_CAP_TOKEN_MASK, x)



#define GCS_CAP_VALID_TOKEN		0x1

#define GCS_CAP_IN_PROGRESS_TOKEN	0x5



#define GCS_CAP(x)	((((unsigned long)x) & GCS_CAP_ADDR_MASK) | \

					       GCS_CAP_VALID_TOKEN)



#define ARM64_FEATURE_FIELD_BITS	4



/* Defined for compatibility only, do not add new users. */