xref: /kvm-unit-tests/lib/x86/asm/barrier.h (revision d77d128fb09ce1a113feec023dd84d3b1cbe5da6)
18226c540SAlexander Gordeev #ifndef _ASM_X86_BARRIER_H_
28226c540SAlexander Gordeev #define _ASM_X86_BARRIER_H_
38226c540SAlexander Gordeev /*
48226c540SAlexander Gordeev  * Copyright (C) 2016, Red Hat Inc, Alexander Gordeev <agordeev@redhat.com>
58226c540SAlexander Gordeev  *
68226c540SAlexander Gordeev  * This work is licensed under the terms of the GNU LGPL, version 2.
78226c540SAlexander Gordeev  */
88226c540SAlexander Gordeev 
98226c540SAlexander Gordeev #define mb()	asm volatile("mfence":::"memory")
108226c540SAlexander Gordeev #define rmb()	asm volatile("lfence":::"memory")
118226c540SAlexander Gordeev #define wmb()	asm volatile("sfence":::"memory")
128226c540SAlexander Gordeev 
1353776986SRoman Kagan #define smp_rmb()	barrier()
1453776986SRoman Kagan #define smp_wmb()	barrier()
1553776986SRoman Kagan 
16*d77d128fSPeter Xu /* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */
17*d77d128fSPeter Xu static inline void rep_nop(void)
18*d77d128fSPeter Xu {
19*d77d128fSPeter Xu 	asm volatile("rep; nop" ::: "memory");
20*d77d128fSPeter Xu }
21*d77d128fSPeter Xu 
22*d77d128fSPeter Xu static inline void cpu_relax(void)
23*d77d128fSPeter Xu {
24*d77d128fSPeter Xu 	rep_nop();
25*d77d128fSPeter Xu }
26*d77d128fSPeter Xu 
278226c540SAlexander Gordeev #endif
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