linux-kernel - [PATCH v4 5/6] arm64: cpufeature: Track 32bit EL0 support

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Date:	Mon, 18 Apr 2016 10:28:36 +0100
From:	Suzuki K Poulose <suzuki.poulose@....com>
To:	linux-arm-kernel@...ts.infradead.org
Cc:	will.deacon@....com, catalin.marinas@....com, mark.rutland@....com,
	linux-kernel@...r.kernel.org, ynorov@...iumnetworks.com,
	Suzuki K Poulose <suzuki.poulose@....com>
Subject: [PATCH v4 5/6] arm64: cpufeature: Track 32bit EL0 support

Add cpu_hwcap bit for keeping track of the support for 32bit EL0.

Tested-by: Yury Norov <ynorov@...iumnetworks.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
---
 arch/arm64/include/asm/cpufeature.h |    8 +++++++-
 arch/arm64/kernel/cpufeature.c      |    9 +++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 7f64285..ca8fb4b 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -35,8 +35,9 @@
 #define ARM64_ALT_PAN_NOT_UAO			10
 #define ARM64_HAS_VIRT_HOST_EXTN		11
 #define ARM64_WORKAROUND_CAVIUM_27456		12
+#define ARM64_HAS_32BIT_EL0			13
 
-#define ARM64_NCAPS				13
+#define ARM64_NCAPS				14
 
 #ifndef __ASSEMBLY__
 
@@ -192,6 +193,11 @@ static inline bool cpu_supports_mixed_endian_el0(void)
 	return id_aa64mmfr0_mixed_endian_el0(read_cpuid(ID_AA64MMFR0_EL1));
 }
 
+static inline bool system_supports_32bit_el0(void)
+{
+	return cpus_have_cap(ARM64_HAS_32BIT_EL0);
+}
+
 static inline bool system_supports_mixed_endian_el0(void)
 {
 	return id_aa64mmfr0_mixed_endian_el0(read_system_reg(SYS_ID_AA64MMFR0_EL1));
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index cfc0cfd..4cd8f23 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -733,6 +733,15 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.capability = ARM64_HAS_VIRT_HOST_EXTN,
 		.matches = runs_at_el2,
 	},
+	{
+		.desc = "32-bit EL0 Support",
+		.capability = ARM64_HAS_32BIT_EL0,
+		.matches = has_cpuid_feature,
+		.sys_reg = SYS_ID_AA64PFR0_EL1,
+		.sign = FTR_UNSIGNED,
+		.field_pos = ID_AA64PFR0_EL0_SHIFT,
+		.min_field_value = ID_AA64PFR0_EL0_32BIT_64BIT,
+	},
 	{},
 };
 
-- 
1.7.9.5