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Commit e3661b12 authored by Marc Zyngier's avatar Marc Zyngier Committed by Will Deacon
Browse files

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: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
[ Added preemptible() check ]
Signed-off-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
[will: remove duplicate initialisation of caps in this_cpu_has_cap]
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 92406f0c

arch/arm64/include/asm/cpufeature.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

arch/arm64/kernel/cpufeature.c

+18 −0
Original line number Diff line number Diff line
@@ -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;