linux-kernel - Re: [PATCH AUTOSEL 4.14 49/89] ARM: 8783/1: NOMMU: Extend check for VBAR support

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Message-ID: <20180912173136.GC3821@sasha-vm>
Date:   Wed, 12 Sep 2018 17:31:37 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     Vladimir Murzin <vladimir.murzin@....com>
CC:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Russell King <rmk+kernel@...linux.org.uk>
Subject: Re: [PATCH AUTOSEL 4.14 49/89] ARM: 8783/1: NOMMU: Extend check for
 VBAR support

On Mon, Sep 10, 2018 at 10:42:05AM +0100, Vladimir Murzin wrote:
>On 02/09/18 14:07, Sasha Levin wrote:
>> From: Vladimir Murzin <vladimir.murzin@....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@....com>
>> Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
>> Signed-off-by: Sasha Levin <alexander.levin@...rosoft.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 91537d90f5f5..08794bb0cada 100644
>> --- a/arch/arm/mm/nommu.c
>> +++ b/arch/arm/mm/nommu.c
>> @@ -305,7 +305,8 @@ 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.

Removed. Thank you!