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