1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  * Copyright (C) 2020 ARM Ltd.
4  */
5 #ifndef __ASM_VDSO_PROCESSOR_H
6 #define __ASM_VDSO_PROCESSOR_H
7 
8 #ifndef __ASSEMBLY__
9 
10 #ifdef CONFIG_CPU_LOONGSON64
11 /*
12  * Loongson-3's SFB (Store-Fill-Buffer) may buffer writes indefinitely when a
13  * tight read loop is executed, because reads take priority over writes & the
14  * hardware (incorrectly) doesn't ensure that writes will eventually occur.
15  *
16  * Since spin loops of any kind should have a cpu_relax() in them, force an SFB
17  * flush from cpu_relax() such that any pending writes will become visible as
18  * expected.
19  */
20 #define cpu_relax()	smp_mb()
21 #else
22 #define cpu_relax()	barrier()
23 #endif
24 
25 #endif /* __ASSEMBLY__ */
26 
27 #endif /* __ASM_VDSO_PROCESSOR_H */
28