arm64: preempt: Provide our own implementation of asm/preempt.h
The asm-generic/preempt.h implementation doesn't make use of the PREEMPT_NEED_RESCHED flag, since this can interact badly with load/store architectures which rely on the preempt_count word being unchanged across an interrupt. However, since we're a 64-bit architecture and the preempt count is only 32 bits wide, we can simply pack it next to the resched flag and load the whole thing in one go, so that a dec-and-test operation doesn't need to load twice. Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: NArd Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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arch/arm64/include/asm/preempt.h
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