Linux kernel mirror (for testing)
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1/* Generic system definitions, based on MN10300 definitions.
2 *
3 * It should be possible to use these on really simple architectures,
4 * but it serves more as a starting point for new ports.
5 *
6 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
7 * Written by David Howells (dhowells@redhat.com)
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public Licence
11 * as published by the Free Software Foundation; either version
12 * 2 of the Licence, or (at your option) any later version.
13 */
14#ifndef __ASM_GENERIC_SYSTEM_H
15#define __ASM_GENERIC_SYSTEM_H
16
17#ifdef __KERNEL__
18#ifndef __ASSEMBLY__
19
20#include <linux/types.h>
21#include <linux/irqflags.h>
22
23#include <asm/cmpxchg-local.h>
24#include <asm/cmpxchg.h>
25
26struct task_struct;
27
28/* context switching is now performed out-of-line in switch_to.S */
29extern struct task_struct *__switch_to(struct task_struct *,
30 struct task_struct *);
31#define switch_to(prev, next, last) \
32 do { \
33 ((last) = __switch_to((prev), (next))); \
34 } while (0)
35
36#define arch_align_stack(x) (x)
37
38#define nop() asm volatile ("nop")
39
40#endif /* !__ASSEMBLY__ */
41
42/*
43 * Force strict CPU ordering.
44 * And yes, this is required on UP too when we're talking
45 * to devices.
46 *
47 * This implementation only contains a compiler barrier.
48 */
49
50#define mb() asm volatile ("": : :"memory")
51#define rmb() mb()
52#define wmb() asm volatile ("": : :"memory")
53
54#ifdef CONFIG_SMP
55#define smp_mb() mb()
56#define smp_rmb() rmb()
57#define smp_wmb() wmb()
58#else
59#define smp_mb() barrier()
60#define smp_rmb() barrier()
61#define smp_wmb() barrier()
62#endif
63
64#define set_mb(var, value) do { var = value; mb(); } while (0)
65#define set_wmb(var, value) do { var = value; wmb(); } while (0)
66
67#define read_barrier_depends() do {} while (0)
68#define smp_read_barrier_depends() do {} while (0)
69
70/*
71 * we make sure local_irq_enable() doesn't cause priority inversion
72 */
73#ifndef __ASSEMBLY__
74
75/* This function doesn't exist, so you'll get a linker error
76 * if something tries to do an invalid xchg(). */
77extern void __xchg_called_with_bad_pointer(void);
78
79static inline
80unsigned long __xchg(unsigned long x, volatile void *ptr, int size)
81{
82 unsigned long ret, flags;
83
84 switch (size) {
85 case 1:
86#ifdef __xchg_u8
87 return __xchg_u8(x, ptr);
88#else
89 local_irq_save(flags);
90 ret = *(volatile u8 *)ptr;
91 *(volatile u8 *)ptr = x;
92 local_irq_restore(flags);
93 return ret;
94#endif /* __xchg_u8 */
95
96 case 2:
97#ifdef __xchg_u16
98 return __xchg_u16(x, ptr);
99#else
100 local_irq_save(flags);
101 ret = *(volatile u16 *)ptr;
102 *(volatile u16 *)ptr = x;
103 local_irq_restore(flags);
104 return ret;
105#endif /* __xchg_u16 */
106
107 case 4:
108#ifdef __xchg_u32
109 return __xchg_u32(x, ptr);
110#else
111 local_irq_save(flags);
112 ret = *(volatile u32 *)ptr;
113 *(volatile u32 *)ptr = x;
114 local_irq_restore(flags);
115 return ret;
116#endif /* __xchg_u32 */
117
118#ifdef CONFIG_64BIT
119 case 8:
120#ifdef __xchg_u64
121 return __xchg_u64(x, ptr);
122#else
123 local_irq_save(flags);
124 ret = *(volatile u64 *)ptr;
125 *(volatile u64 *)ptr = x;
126 local_irq_restore(flags);
127 return ret;
128#endif /* __xchg_u64 */
129#endif /* CONFIG_64BIT */
130
131 default:
132 __xchg_called_with_bad_pointer();
133 return x;
134 }
135}
136
137#define xchg(ptr, x) \
138 ((__typeof__(*(ptr))) __xchg((unsigned long)(x), (ptr), sizeof(*(ptr))))
139
140#endif /* !__ASSEMBLY__ */
141
142#endif /* __KERNEL__ */
143#endif /* __ASM_GENERIC_SYSTEM_H */