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author | Marc Zyngier <marc.zyngier@arm.com> | 2016-04-22 11:25:32 (GMT) |
---|---|---|
committer | Will Deacon <will.deacon@arm.com> | 2016-04-25 14:13:05 (GMT) |
commit | e3661b128e53ee281e1e7c589a5b647890bd6d7c (patch) | |
tree | 456828adc71dc6cc53861c704a55ce425805db83 | |
parent | 92406f0cc9e3d5cc77bf3de6d68c9c2373dcd701 (diff) | |
download | linux-e3661b128e53ee281e1e7c589a5b647890bd6d7c.tar.xz |
arm64: Allow a capability to be checked on a single CPU
Now that the capabilities are only available once all the CPUs
have booted, we're unable to check for a particular feature
in any subsystem that gets initialized before then.
In order to support this, introduce a local_cpu_has_cap() function
that tests for the presence of a given capability independently
of the whole framework.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
[ Added preemptible() check ]
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
[will: remove duplicate initialisation of caps in this_cpu_has_cap]
Signed-off-by: Will Deacon <will.deacon@arm.com>
-rw-r--r-- | arch/arm64/include/asm/cpufeature.h | 2 | ||||
-rw-r--r-- | arch/arm64/kernel/cpufeature.c | 18 |
2 files changed, 20 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index e501e4a..d39db63 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -109,6 +109,8 @@ struct arm64_cpu_capabilities { extern DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS); +bool this_cpu_has_cap(unsigned int cap); + static inline bool cpu_have_feature(unsigned int num) { return elf_hwcap & (1UL << num); diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 54abd9b..2b09dc4 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1010,6 +1010,24 @@ static void __init setup_feature_capabilities(void) enable_cpu_capabilities(arm64_features); } +/* + * Check if the current CPU has a given feature capability. + * Should be called from non-preemptible context. + */ +bool this_cpu_has_cap(unsigned int cap) +{ + const struct arm64_cpu_capabilities *caps; + + if (WARN_ON(preemptible())) + return false; + + for (caps = arm64_features; caps->desc; caps++) + if (caps->capability == cap && caps->matches) + return caps->matches(caps, SCOPE_LOCAL_CPU); + + return false; +} + void __init setup_cpu_features(void) { u32 cwg; |