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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>
This commit is contained in:
Marc Zyngier 2016-04-22 12:25:32 +01:00 committed by Will Deacon
parent 92406f0cc9
commit e3661b128e
2 changed files with 20 additions and 0 deletions
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2
arch/arm64/include/asm/cpufeature.h
View File

@ -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);

18
arch/arm64/kernel/cpufeature.c
View File

@ -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;