462cda505f
Taken from the linux kernel. Reviewed-by: Sergey Fedorov <sergey.fedorov@linaro.org> Reviewed-by: Richard Henderson <rth@twiddle.net> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <1465412133-3029-5-git-send-email-cota@braap.org> Signed-off-by: Richard Henderson <rth@twiddle.net>
31 lines
799 B
C
31 lines
799 B
C
/*
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* Copyright (C) 2016, Emilio G. Cota <cota@braap.org>
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*
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* License: GNU GPL, version 2.
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* See the COPYING file in the top-level directory.
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*/
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#ifndef QEMU_PROCESSOR_H
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#define QEMU_PROCESSOR_H
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#include "qemu/atomic.h"
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#if defined(__i386__) || defined(__x86_64__)
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# define cpu_relax() asm volatile("rep; nop" ::: "memory")
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#elif defined(__ia64__)
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# define cpu_relax() asm volatile("hint @pause" ::: "memory")
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#elif defined(__aarch64__)
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# define cpu_relax() asm volatile("yield" ::: "memory")
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#elif defined(__powerpc64__)
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/* set Hardware Multi-Threading (HMT) priority to low; then back to medium */
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# define cpu_relax() asm volatile("or 1, 1, 1;" \
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"or 2, 2, 2;" ::: "memory")
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#else
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# define cpu_relax() barrier()
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#endif
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#endif /* QEMU_PROCESSOR_H */
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