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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Memory barrier definitions. This is based on information published
4 * in the Processor Abstraction Layer and the System Abstraction Layer
5 * manual.
6 *
7 * Copyright (C) 1998-2003 Hewlett-Packard Co
8 * David Mosberger-Tang <davidm@hpl.hp.com>
9 * Copyright (C) 1999 Asit Mallick <asit.k.mallick@intel.com>
10 * Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
11 */
12#ifndef _ASM_IA64_BARRIER_H
13#define _ASM_IA64_BARRIER_H
14
15#include <linux/compiler.h>
16
17/*
18 * Macros to force memory ordering. In these descriptions, "previous"
19 * and "subsequent" refer to program order; "visible" means that all
20 * architecturally visible effects of a memory access have occurred
21 * (at a minimum, this means the memory has been read or written).
22 *
23 * wmb(): Guarantees that all preceding stores to memory-
24 * like regions are visible before any subsequent
25 * stores and that all following stores will be
26 * visible only after all previous stores.
27 * rmb(): Like wmb(), but for reads.
28 * mb(): wmb()/rmb() combo, i.e., all previous memory
29 * accesses are visible before all subsequent
30 * accesses and vice versa. This is also known as
31 * a "fence."
32 *
33 * Note: "mb()" and its variants cannot be used as a fence to order
34 * accesses to memory mapped I/O registers. For that, mf.a needs to
35 * be used. However, we don't want to always use mf.a because (a)
36 * it's (presumably) much slower than mf and (b) mf.a is supported for
37 * sequential memory pages only.
38 */
39#define mb() ia64_mf()
40#define rmb() mb()
41#define wmb() mb()
42
43#define dma_rmb() mb()
44#define dma_wmb() mb()
45
46# define __smp_mb() mb()
47
48#define __smp_mb__before_atomic() barrier()
49#define __smp_mb__after_atomic() barrier()
50
51/*
52 * IA64 GCC turns volatile stores into st.rel and volatile loads into ld.acq no
53 * need for asm trickery!
54 */
55
56#define __smp_store_release(p, v) \
57do { \
58 compiletime_assert_atomic_type(*p); \
59 barrier(); \
60 WRITE_ONCE(*p, v); \
61} while (0)
62
63#define __smp_load_acquire(p) \
64({ \
65 typeof(*p) ___p1 = READ_ONCE(*p); \
66 compiletime_assert_atomic_type(*p); \
67 barrier(); \
68 ___p1; \
69})
70
71/*
72 * The group barrier in front of the rsm & ssm are necessary to ensure
73 * that none of the previous instructions in the same group are
74 * affected by the rsm/ssm.
75 */
76
77#include <asm-generic/barrier.h>
78
79#endif /* _ASM_IA64_BARRIER_H */
1/*
2 * Memory barrier definitions. This is based on information published
3 * in the Processor Abstraction Layer and the System Abstraction Layer
4 * manual.
5 *
6 * Copyright (C) 1998-2003 Hewlett-Packard Co
7 * David Mosberger-Tang <davidm@hpl.hp.com>
8 * Copyright (C) 1999 Asit Mallick <asit.k.mallick@intel.com>
9 * Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
10 */
11#ifndef _ASM_IA64_BARRIER_H
12#define _ASM_IA64_BARRIER_H
13
14#include <linux/compiler.h>
15
16/*
17 * Macros to force memory ordering. In these descriptions, "previous"
18 * and "subsequent" refer to program order; "visible" means that all
19 * architecturally visible effects of a memory access have occurred
20 * (at a minimum, this means the memory has been read or written).
21 *
22 * wmb(): Guarantees that all preceding stores to memory-
23 * like regions are visible before any subsequent
24 * stores and that all following stores will be
25 * visible only after all previous stores.
26 * rmb(): Like wmb(), but for reads.
27 * mb(): wmb()/rmb() combo, i.e., all previous memory
28 * accesses are visible before all subsequent
29 * accesses and vice versa. This is also known as
30 * a "fence."
31 *
32 * Note: "mb()" and its variants cannot be used as a fence to order
33 * accesses to memory mapped I/O registers. For that, mf.a needs to
34 * be used. However, we don't want to always use mf.a because (a)
35 * it's (presumably) much slower than mf and (b) mf.a is supported for
36 * sequential memory pages only.
37 */
38#define mb() ia64_mf()
39#define rmb() mb()
40#define wmb() mb()
41#define read_barrier_depends() do { } while(0)
42
43#ifdef CONFIG_SMP
44# define smp_mb() mb()
45# define smp_rmb() rmb()
46# define smp_wmb() wmb()
47# define smp_read_barrier_depends() read_barrier_depends()
48#else
49# define smp_mb() barrier()
50# define smp_rmb() barrier()
51# define smp_wmb() barrier()
52# define smp_read_barrier_depends() do { } while(0)
53#endif
54
55/*
56 * XXX check on this ---I suspect what Linus really wants here is
57 * acquire vs release semantics but we can't discuss this stuff with
58 * Linus just yet. Grrr...
59 */
60#define set_mb(var, value) do { (var) = (value); mb(); } while (0)
61
62/*
63 * The group barrier in front of the rsm & ssm are necessary to ensure
64 * that none of the previous instructions in the same group are
65 * affected by the rsm/ssm.
66 */
67
68#endif /* _ASM_IA64_BARRIER_H */