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1#ifndef _ASM_GENERIC_PERCPU_H_
2#define _ASM_GENERIC_PERCPU_H_
3#include <linux/compiler.h>
4#include <linux/threads.h>
5
6/*
7 * Determine the real variable name from the name visible in the
8 * kernel sources.
9 */
10#define per_cpu_var(var) per_cpu__##var
11
12#ifdef CONFIG_SMP
13
14/*
15 * per_cpu_offset() is the offset that has to be added to a
16 * percpu variable to get to the instance for a certain processor.
17 *
18 * Most arches use the __per_cpu_offset array for those offsets but
19 * some arches have their own ways of determining the offset (x86_64, s390).
20 */
21#ifndef __per_cpu_offset
22extern unsigned long __per_cpu_offset[NR_CPUS];
23
24#define per_cpu_offset(x) (__per_cpu_offset[x])
25#endif
26
27/*
28 * Determine the offset for the currently active processor.
29 * An arch may define __my_cpu_offset to provide a more effective
30 * means of obtaining the offset to the per cpu variables of the
31 * current processor.
32 */
33#ifndef __my_cpu_offset
34#define __my_cpu_offset per_cpu_offset(raw_smp_processor_id())
35#endif
36#ifdef CONFIG_DEBUG_PREEMPT
37#define my_cpu_offset per_cpu_offset(smp_processor_id())
38#else
39#define my_cpu_offset __my_cpu_offset
40#endif
41
42/*
43 * Add a offset to a pointer but keep the pointer as is.
44 *
45 * Only S390 provides its own means of moving the pointer.
46 */
47#ifndef SHIFT_PERCPU_PTR
48#define SHIFT_PERCPU_PTR(__p, __offset) RELOC_HIDE((__p), (__offset))
49#endif
50
51/*
52 * A percpu variable may point to a discarded regions. The following are
53 * established ways to produce a usable pointer from the percpu variable
54 * offset.
55 */
56#define per_cpu(var, cpu) \
57 (*SHIFT_PERCPU_PTR(&per_cpu_var(var), per_cpu_offset(cpu)))
58#define __get_cpu_var(var) \
59 (*SHIFT_PERCPU_PTR(&per_cpu_var(var), my_cpu_offset))
60#define __raw_get_cpu_var(var) \
61 (*SHIFT_PERCPU_PTR(&per_cpu_var(var), __my_cpu_offset))
62
63
64#ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA
65extern void setup_per_cpu_areas(void);
66#endif
67
68#else /* ! SMP */
69
70#define per_cpu(var, cpu) (*((void)(cpu), &per_cpu_var(var)))
71#define __get_cpu_var(var) per_cpu_var(var)
72#define __raw_get_cpu_var(var) per_cpu_var(var)
73
74#endif /* SMP */
75
76#ifndef PER_CPU_ATTRIBUTES
77#define PER_CPU_ATTRIBUTES
78#endif
79
80#define DECLARE_PER_CPU(type, name) extern PER_CPU_ATTRIBUTES \
81 __typeof__(type) per_cpu_var(name)
82
83/*
84 * Optional methods for optimized non-lvalue per-cpu variable access.
85 *
86 * @var can be a percpu variable or a field of it and its size should
87 * equal char, int or long. percpu_read() evaluates to a lvalue and
88 * all others to void.
89 *
90 * These operations are guaranteed to be atomic w.r.t. preemption.
91 * The generic versions use plain get/put_cpu_var(). Archs are
92 * encouraged to implement single-instruction alternatives which don't
93 * require preemption protection.
94 */
95#ifndef percpu_read
96# define percpu_read(var) \
97 ({ \
98 typeof(per_cpu_var(var)) __tmp_var__; \
99 __tmp_var__ = get_cpu_var(var); \
100 put_cpu_var(var); \
101 __tmp_var__; \
102 })
103#endif
104
105#define __percpu_generic_to_op(var, val, op) \
106do { \
107 get_cpu_var(var) op val; \
108 put_cpu_var(var); \
109} while (0)
110
111#ifndef percpu_write
112# define percpu_write(var, val) __percpu_generic_to_op(var, (val), =)
113#endif
114
115#ifndef percpu_add
116# define percpu_add(var, val) __percpu_generic_to_op(var, (val), +=)
117#endif
118
119#ifndef percpu_sub
120# define percpu_sub(var, val) __percpu_generic_to_op(var, (val), -=)
121#endif
122
123#ifndef percpu_and
124# define percpu_and(var, val) __percpu_generic_to_op(var, (val), &=)
125#endif
126
127#ifndef percpu_or
128# define percpu_or(var, val) __percpu_generic_to_op(var, (val), |=)
129#endif
130
131#ifndef percpu_xor
132# define percpu_xor(var, val) __percpu_generic_to_op(var, (val), ^=)
133#endif
134
135#endif /* _ASM_GENERIC_PERCPU_H_ */