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#ifndef __QEMU_BARRIER_H
#define __QEMU_BARRIER_H 1
/* Compiler barrier */
#define barrier() asm volatile("" ::: "memory")
#if defined(__i386__)
#include "qemu/compiler.h" /* QEMU_GNUC_PREREQ */
/*
* Because of the strongly ordered x86 storage model, wmb() and rmb() are nops
* on x86(well, a compiler barrier only). Well, at least as long as
* qemu doesn't do accesses to write-combining memory or non-temporal
* load/stores from C code.
*/
#define smp_wmb() barrier()
#define smp_rmb() barrier()
/*
* We use GCC builtin if it's available, as that can use
* mfence on 32 bit as well, e.g. if built with -march=pentium-m.
* However, on i386, there seem to be known bugs as recently as 4.3.
* */
#if QEMU_GNUC_PREREQ(4, 4)
#define smp_mb() __sync_synchronize()
#else
#define smp_mb() asm volatile("lock; addl $0,0(%%esp) " ::: "memory")
#endif
#elif defined(__x86_64__)
#define smp_wmb() barrier()
#define smp_rmb() barrier()
#define smp_mb() asm volatile("mfence" ::: "memory")
#elif defined(_ARCH_PPC)
/*
* We use an eieio() for wmb() on powerpc. This assumes we don't
* need to order cacheable and non-cacheable stores with respect to
* each other
*/
#define smp_wmb() asm volatile("eieio" ::: "memory")
#if defined(__powerpc64__)
#define smp_rmb() asm volatile("lwsync" ::: "memory")
#else
#define smp_rmb() asm volatile("sync" ::: "memory")
#endif
#define smp_mb() asm volatile("sync" ::: "memory")
#else
/*
* For (host) platforms we don't have explicit barrier definitions
* for, we use the gcc __sync_synchronize() primitive to generate a
* full barrier. This should be safe on all platforms, though it may
* be overkill for wmb() and rmb().
*/
#define smp_wmb() __sync_synchronize()
#define smp_mb() __sync_synchronize()
#define smp_rmb() __sync_synchronize()
#endif
#endif
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