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

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Date:   Sun, 2 Sep 2018 13:07:11 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Vladimir Murzin <vladimir.murzin@....com>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL 4.14 49/89] ARM: 8783/1: NOMMU: Extend check for VBAR
 support

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;
 }
 
-- 
2.17.1