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arm64: fpsimd: Make sure SVE setup is complete before SIMD is used

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In-kernel users of NEON rely on may_use_simd() to check if the SIMD
can be used. However, we must initialize the SVE before SIMD can
be used. Add a sanity check to make sure that we have completed the
SVE setup before anyone uses the SIMD.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Suzuki K Poulose 2020-01-13 23:30:18 +00:00 committed by Will Deacon
parent b51c6ac220
commit 0cd82feb01
1 changed files with 6 additions and 2 deletions
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8
arch/arm64/include/asm/simd.h
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@ -26,6 +26,8 @@ DECLARE_PER_CPU(bool, fpsimd_context_busy);
static __must_check inline bool may_use_simd(void)
{
/*
* We must make sure that the SVE has been initialized properly
* before using the SIMD in kernel.
* fpsimd_context_busy is only set while preemption is disabled,
* and is clear whenever preemption is enabled. Since
* this_cpu_read() is atomic w.r.t. preemption, fpsimd_context_busy
@ -33,8 +35,10 @@ static __must_check inline bool may_use_simd(void)
* migrated, and if it's clear we cannot be migrated to a CPU
* where it is set.
*/
return !in_irq() && !irqs_disabled() && !in_nmi() &&
!this_cpu_read(fpsimd_context_busy);
return !WARN_ON(!system_capabilities_finalized()) &&
system_supports_fpsimd() &&
!in_irq() && !irqs_disabled() && !in_nmi() &&
!this_cpu_read(fpsimd_context_busy);
}
#else /* ! CONFIG_KERNEL_MODE_NEON */