Commit 69bb02eb authored by Marc Zyngier's avatar Marc Zyngier
Browse files

arm64: Add HWCAP advertising FEAT_WFXT 



In order to allow userspace to enjoy WFET, add a new HWCAP that
advertises it when available.

Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220419182755.601427-9-maz@kernel.org
parent bdcc2f28

Documentation/arm64/cpu-feature-registers.rst

+2 −0
Original line number Diff line number Diff line
@@ -290,6 +290,8 @@ infrastructure: 
     +------------------------------+---------+---------+

     | RPRES                        | [7-4]   |    y    |

     +------------------------------+---------+---------+

     | WFXT                         | [3-0]   |    y    |

     +------------------------------+---------+---------+





Appendix I: Example

Documentation/arm64/elf_hwcaps.rst

+4 −0
Original line number Diff line number Diff line
@@ -264,6 +264,10 @@ HWCAP2_MTE3 
    Functionality implied by ID_AA64PFR1_EL1.MTE == 0b0011, as described

    by Documentation/arm64/memory-tagging-extension.rst.



HWCAP2_WFXT



    Functionality implied by ID_AA64ISAR2_EL1.WFXT == 0b0010.



4. Unused AT_HWCAP bits

-----------------------

arch/arm64/include/asm/hwcap.h

+1 −0
Original line number Diff line number Diff line
@@ -109,6 +109,7 @@ 
#define KERNEL_HWCAP_AFP		__khwcap2_feature(AFP)

#define KERNEL_HWCAP_RPRES		__khwcap2_feature(RPRES)

#define KERNEL_HWCAP_MTE3		__khwcap2_feature(MTE3)

#define KERNEL_HWCAP_WFXT		__khwcap2_feature(WFXT)



/*

 * This yields a mask that user programs can use to figure out what

arch/arm64/include/uapi/asm/hwcap.h

+1 −0
Original line number Diff line number Diff line
@@ -79,5 +79,6 @@ 
#define HWCAP2_AFP		(1 << 20)

#define HWCAP2_RPRES		(1 << 21)

#define HWCAP2_MTE3		(1 << 22)

#define HWCAP2_WFXT		(1 << 23)



#endif /* _UAPI__ASM_HWCAP_H */

arch/arm64/kernel/cpufeature.c

+2 −0
Original line number Diff line number Diff line
@@ -237,6 +237,7 @@ static const struct arm64_ftr_bits ftr_id_aa64isar2[] = { 
	ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),

		       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR2_GPA3_SHIFT, 4, 0),

	ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64ISAR2_RPRES_SHIFT, 4, 0),

	ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64ISAR2_WFXT_SHIFT, 4, 0),

	ARM64_FTR_END,

};
@@ -2575,6 +2576,7 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = { 
	HWCAP_CAP(SYS_ID_AA64MMFR0_EL1, ID_AA64MMFR0_ECV_SHIFT, 4, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_ECV),

	HWCAP_CAP(SYS_ID_AA64MMFR1_EL1, ID_AA64MMFR1_AFP_SHIFT, 4, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_AFP),

	HWCAP_CAP(SYS_ID_AA64ISAR2_EL1, ID_AA64ISAR2_RPRES_SHIFT, 4, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_RPRES),

	HWCAP_CAP(SYS_ID_AA64ISAR2_EL1, ID_AA64ISAR2_WFXT_SHIFT, 4, FTR_UNSIGNED, ID_AA64ISAR2_WFXT_SUPPORTED, CAP_HWCAP, KERNEL_HWCAP_WFXT),

	{},

};