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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copied from the kernel sources to tools/:
*
* Memory barrier definitions. This is based on information published
* in the Processor Abstraction Layer and the System Abstraction Layer
* manual.
*
* Copyright (C) 1998-2003 Hewlett-Packard Co
* David Mosberger-Tang <davidm@hpl.hp.com>
* Copyright (C) 1999 Asit Mallick <asit.k.mallick@intel.com>
* Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
*/
#ifndef _TOOLS_LINUX_ASM_IA64_BARRIER_H
#define _TOOLS_LINUX_ASM_IA64_BARRIER_H
#include <linux/compiler.h>
/*
* Macros to force memory ordering. In these descriptions, "previous"
* and "subsequent" refer to program order; "visible" means that all
* architecturally visible effects of a memory access have occurred
* (at a minimum, this means the memory has been read or written).
*
* wmb(): Guarantees that all preceding stores to memory-
* like regions are visible before any subsequent
* stores and that all following stores will be
* visible only after all previous stores.
* rmb(): Like wmb(), but for reads.
* mb(): wmb()/rmb() combo, i.e., all previous memory
* accesses are visible before all subsequent
* accesses and vice versa. This is also known as
* a "fence."
*
* Note: "mb()" and its variants cannot be used as a fence to order
* accesses to memory mapped I/O registers. For that, mf.a needs to
* be used. However, we don't want to always use mf.a because (a)
* it's (presumably) much slower than mf and (b) mf.a is supported for
* sequential memory pages only.
*/
#define mb() ia64_mf()
#define rmb() mb()
#define wmb() mb()
#endif /* _TOOLS_LINUX_ASM_IA64_BARRIER_H */
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