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SubjectRe: [PATCH AUTOSEL 4.18 074/131] ARM: 8783/1: NOMMU: Extend check for VBAR support
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On 02/09/18 14:04, Sasha Levin wrote:
> From: Vladimir Murzin <vladimir.murzin@arm.com>
>
> [ Upstream commit c803ce3f18bd93b3b4a15d1da0c5b5ebc60e0b85 ]
>
> ARMv8R adds support for VBAR and updates ID_PFR1 with the new filed
> Sec_frac (bits [23:20]):
>
> Security fractional field. When the Security field is 0000, determines
> the support for features from the ARMv7 Security Extensions. Permitted
> values are:
>
> 0000 No features from the ARMv7 Security Extensions are implemented.
> This value is not supported in ARMv8 if ID_PFR1 bits [7:4] are zero.
>
> 0001 The implementation includes the VBAR, and the TCR.PD0 and TCR.PD1
> bits.
>
> 0010 As for 0001, plus the ability to access Secure or Non-secure
> physical memory is supported.
>
> All other values are reserved.
>
> This field is only valid when ID_PFR1[7:4] == 0, otherwise it holds
> the value 0000.
>
> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
> ---
> arch/arm/mm/nommu.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c
> index 5dd6c58d653b..7d67c70bbded 100644
> --- a/arch/arm/mm/nommu.c
> +++ b/arch/arm/mm/nommu.c
> @@ -53,7 +53,8 @@ static inline bool security_extensions_enabled(void)
> {
> /* Check CPUID Identification Scheme before ID_PFR1 read */
> if ((read_cpuid_id() & 0x000f0000) == 0x000f0000)
> - return !!cpuid_feature_extract(CPUID_EXT_PFR1, 4);
> + return cpuid_feature_extract(CPUID_EXT_PFR1, 4) ||
> + cpuid_feature_extract(CPUID_EXT_PFR1, 20);
> return 0;
> }
>
>

NAK - it is not stable material.

Thanks
Vladimir

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