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arm64: kernel: Add cpuid_feature_extract_field() for 4bit sign extension

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Based on arch/arm/include/asm/cputype.h, this function does the
shifting and sign extension necessary when accessing cpu feature fields.

Signed-off-by: James Morse <james.morse@arm.com>
Suggested-by: Russell King <linux@arm.linux.org.uk>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
James Morse 2015-07-21 13:23:26 +01:00 committed by Will Deacon
parent ae2fb7ece9
commit 79b0e09a3c
1 changed files with 7 additions and 0 deletions
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7
arch/arm64/include/asm/cpufeature.h
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@ -70,6 +70,13 @@ static inline void cpus_set_cap(unsigned int num)
__set_bit(num, cpu_hwcaps);
}
static inline int __attribute_const__ cpuid_feature_extract_field(u64 features,
int field)
{
return (s64)(features << (64 - 4 - field)) >> (64 - 4);
}
void check_cpu_capabilities(const struct arm64_cpu_capabilities *caps,
const char *info);
void check_local_cpu_errata(void);