1/* SPDX-License-Identifier: GPL-2.0 */
 2/*
 3 * Copied from the kernel sources to tools/:
 4 *
 5 * Memory barrier definitions.  This is based on information published
 6 * in the Processor Abstraction Layer and the System Abstraction Layer
 7 * manual.
 8 *
 9 * Copyright (C) 1998-2003 Hewlett-Packard Co
10 *	David Mosberger-Tang <davidm@hpl.hp.com>
11 * Copyright (C) 1999 Asit Mallick <asit.k.mallick@intel.com>
12 * Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
13 */
14#ifndef _TOOLS_LINUX_ASM_IA64_BARRIER_H
15#define _TOOLS_LINUX_ASM_IA64_BARRIER_H
16
17#include <linux/compiler.h>
18
19/*
20 * Macros to force memory ordering.  In these descriptions, "previous"
21 * and "subsequent" refer to program order; "visible" means that all
22 * architecturally visible effects of a memory access have occurred
23 * (at a minimum, this means the memory has been read or written).
24 *
25 *   wmb():	Guarantees that all preceding stores to memory-
26 *		like regions are visible before any subsequent
27 *		stores and that all following stores will be
28 *		visible only after all previous stores.
29 *   rmb():	Like wmb(), but for reads.
30 *   mb():	wmb()/rmb() combo, i.e., all previous memory
31 *		accesses are visible before all subsequent
32 *		accesses and vice versa.  This is also known as
33 *		a "fence."
34 *
35 * Note: "mb()" and its variants cannot be used as a fence to order
36 * accesses to memory mapped I/O registers.  For that, mf.a needs to
37 * be used.  However, we don't want to always use mf.a because (a)
38 * it's (presumably) much slower than mf and (b) mf.a is supported for
39 * sequential memory pages only.
40 */
41
42/* XXX From arch/ia64/include/uapi/asm/gcc_intrin.h */
43#define ia64_mf()       asm volatile ("mf" ::: "memory")
44
45#define mb()		ia64_mf()
46#define rmb()		mb()
47#define wmb()		mb()
48
49#define smp_store_release(p, v)			\
50do {						\
51	barrier();				\
52	WRITE_ONCE(*p, v);			\
53} while (0)
54
55#define smp_load_acquire(p)			\
56({						\
57	typeof(*p) ___p1 = READ_ONCE(*p);	\
58	barrier();				\
59	___p1;					\
60})
61
62#endif /* _TOOLS_LINUX_ASM_IA64_BARRIER_H */