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Subject[PATCH 4.4 071/113] arm64: cpufeature: Track 32bit EL0 support
Date
4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Suzuki K Poulose <suzuki.poulose@arm.com>

commit 042446a31e3803d81c7e618dd80928dc3dce70c5 upstream.

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

Tested-by: Yury Norov <ynorov@caviumnetworks.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/include/asm/cpufeature.h | 8 +++++++-
arch/arm64/include/asm/sysreg.h | 1 +
arch/arm64/kernel/cpufeature.c | 8 ++++++++
3 files changed, 16 insertions(+), 1 deletion(-)

--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -31,8 +31,9 @@
#define ARM64_WORKAROUND_CAVIUM_23154 6
#define ARM64_WORKAROUND_834220 7
#define ARM64_WORKAROUND_CAVIUM_27456 8
+#define ARM64_HAS_32BIT_EL0 9

-#define ARM64_NCAPS 9
+#define ARM64_NCAPS 10

#ifndef __ASSEMBLY__

@@ -180,6 +181,11 @@ static inline bool cpu_supports_mixed_en
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));
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -109,6 +109,7 @@
#define ID_AA64PFR0_ASIMD_SUPPORTED 0x0
#define ID_AA64PFR0_EL1_64BIT_ONLY 0x1
#define ID_AA64PFR0_EL0_64BIT_ONLY 0x1
+#define ID_AA64PFR0_EL0_32BIT_64BIT 0x2

/* id_aa64mmfr0 */
#define ID_AA64MMFR0_TGRAN4_SHIFT 28
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -653,6 +653,14 @@ static const struct arm64_cpu_capabiliti
.min_field_value = 2,
},
#endif /* CONFIG_AS_LSE && CONFIG_ARM64_LSE_ATOMICS */
+ {
+ .desc = "32-bit EL0 Support",
+ .capability = ARM64_HAS_32BIT_EL0,
+ .matches = has_cpuid_feature,
+ .sys_reg = SYS_ID_AA64PFR0_EL1,
+ .field_pos = ID_AA64PFR0_EL0_SHIFT,
+ .min_field_value = ID_AA64PFR0_EL0_32BIT_64BIT,
+ },
{},
};


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