Re: [PATCH v4 4/6] arm64: Expose DC CVADP to userspace

[Dave Martin <Dave.Martin@arm.com>]

On Wed, Apr 03, 2019 at 11:56:26AM +0100, Andrew Murray wrote:
> ARMv8.5 builds upon the ARMv8.2 DC CVAP instruction by introducing a DC
> CVADP instruction which cleans the data cache to the point of deep
> persistence. Let's expose this support via the arm64 ELF hwcaps.
> 
> Signed-off-by: Andrew Murray <andrew.murray@arm.com>

Reviewed-by: Dave Martin <Dave.Martin@arm.com>

> ---
>  Documentation/arm64/elf_hwcaps.txt  | 4 ++++
>  arch/arm64/include/asm/hwcap.h      | 1 +
>  arch/arm64/include/uapi/asm/hwcap.h | 5 +++++
>  arch/arm64/kernel/cpufeature.c      | 1 +
>  arch/arm64/kernel/cpuinfo.c         | 1 +
>  5 files changed, 12 insertions(+)
> 
> diff --git a/Documentation/arm64/elf_hwcaps.txt b/Documentation/arm64/elf_hwcaps.txt
> index c04f8e87bab8..7b591c1dcb53 100644
> --- a/Documentation/arm64/elf_hwcaps.txt
> +++ b/Documentation/arm64/elf_hwcaps.txt
> @@ -135,6 +135,10 @@ HWCAP_DCPOP
>  
>      Functionality implied by ID_AA64ISAR1_EL1.DPB == 0b0001.
>  
> +HWCAP2_DCPODP
> +
> +    Functionality implied by ID_AA64ISAR1_EL1.DPB == 0b0010.
> +
>  HWCAP_SHA3
>  
>      Functionality implied by ID_AA64ISAR0_EL1.SHA3 == 0b0001.
> diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h
> index 509ee0d2fa0f..732bdd7286c8 100644
> --- a/arch/arm64/include/asm/hwcap.h
> +++ b/arch/arm64/include/asm/hwcap.h
> @@ -85,6 +85,7 @@
>  #define KERNEL_HWCAP_PACG		__khwcap_feature(PACG)
>  
>  #define __khwcap2_feature(x)		(ilog2(HWCAP2_ ## x) + 32)
> +#define KERNEL_HWCAP_DCPODP		__khwcap2_feature(DCPODP)
>  
>  #ifndef __ASSEMBLY__
>  
> diff --git a/arch/arm64/include/uapi/asm/hwcap.h b/arch/arm64/include/uapi/asm/hwcap.h
> index 453b45af80b7..d64af3913a9e 100644
> --- a/arch/arm64/include/uapi/asm/hwcap.h
> +++ b/arch/arm64/include/uapi/asm/hwcap.h
> @@ -53,4 +53,9 @@
>  #define HWCAP_PACA		(1 << 30)
>  #define HWCAP_PACG		(1UL << 31)
>  
> +/*
> + * HWCAP2 flags - for AT_HWCAP2
> + */
> +#define HWCAP2_DCPODP		(1 << 0)
> +
>  #endif /* _UAPI__ASM_HWCAP_H */
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index a655d1bb1186..f8b682a3a9f4 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -1591,6 +1591,7 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
>  	HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_ASIMD_SHIFT, FTR_SIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_ASIMDHP),
>  	HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_DIT_SHIFT, FTR_SIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_DIT),
>  	HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_DPB_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_DCPOP),
> +	HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_DPB_SHIFT, FTR_UNSIGNED, 2, CAP_HWCAP, KERNEL_HWCAP_DCPODP),
>  	HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_JSCVT_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_JSCVT),
>  	HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_FCMA_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_FCMA),
>  	HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_LRCPC_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_LRCPC),
> diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
> index 810db95f293f..093ca53ce1d1 100644
> --- a/arch/arm64/kernel/cpuinfo.c
> +++ b/arch/arm64/kernel/cpuinfo.c
> @@ -85,6 +85,7 @@ static const char *const hwcap_str[] = {
>  	"sb",
>  	"paca",
>  	"pacg",
> +	"dcpodp",
>  	NULL
>  };
>  
> -- 
> 2.21.0
>