https://github.com/torvalds/linux
Raw File
Tip revision: 1291a0d5049dbc06baaaf66a9ff3f53db493b19b authored by Linus Torvalds on 18 December 2017, 02:59:59 UTC
Linux 4.15-rc4
Tip revision: 1291a0d
barrier.h
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_UM_BARRIER_H_
#define _ASM_UM_BARRIER_H_

#include <asm/asm.h>
#include <asm/segment.h>
#include <asm/cpufeatures.h>
#include <asm/cmpxchg.h>
#include <asm/nops.h>

#include <linux/kernel.h>
#include <linux/irqflags.h>

/*
 * Force strict CPU ordering.
 * And yes, this is required on UP too when we're talking
 * to devices.
 */
#ifdef CONFIG_X86_32

#define mb()	alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
#define rmb()	alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)
#define wmb()	alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)

#else /* CONFIG_X86_32 */

#define mb()	asm volatile("mfence" : : : "memory")
#define rmb()	asm volatile("lfence" : : : "memory")
#define wmb()	asm volatile("sfence" : : : "memory")

#endif /* CONFIG_X86_32 */

#ifdef CONFIG_X86_PPRO_FENCE
#define dma_rmb()	rmb()
#else /* CONFIG_X86_PPRO_FENCE */
#define dma_rmb()	barrier()
#endif /* CONFIG_X86_PPRO_FENCE */
#define dma_wmb()	barrier()

#include <asm-generic/barrier.h>

#endif
back to top