Root/include/asm-generic/percpu.h

1#ifndef _ASM_GENERIC_PERCPU_H_
2#define _ASM_GENERIC_PERCPU_H_
3
4#include <linux/compiler.h>
5#include <linux/threads.h>
6#include <linux/percpu-defs.h>
7
8#ifdef CONFIG_SMP
9
10/*
11 * per_cpu_offset() is the offset that has to be added to a
12 * percpu variable to get to the instance for a certain processor.
13 *
14 * Most arches use the __per_cpu_offset array for those offsets but
15 * some arches have their own ways of determining the offset (x86_64, s390).
16 */
17#ifndef __per_cpu_offset
18extern unsigned long __per_cpu_offset[NR_CPUS];
19
20#define per_cpu_offset(x) (__per_cpu_offset[x])
21#endif
22
23/*
24 * Determine the offset for the currently active processor.
25 * An arch may define __my_cpu_offset to provide a more effective
26 * means of obtaining the offset to the per cpu variables of the
27 * current processor.
28 */
29#ifndef __my_cpu_offset
30#define __my_cpu_offset per_cpu_offset(raw_smp_processor_id())
31#endif
32#ifdef CONFIG_DEBUG_PREEMPT
33#define my_cpu_offset per_cpu_offset(smp_processor_id())
34#else
35#define my_cpu_offset __my_cpu_offset
36#endif
37
38/*
39 * Add a offset to a pointer but keep the pointer as is.
40 *
41 * Only S390 provides its own means of moving the pointer.
42 */
43#ifndef SHIFT_PERCPU_PTR
44/* Weird cast keeps both GCC and sparse happy. */
45#define SHIFT_PERCPU_PTR(__p, __offset) ({ \
46    __verify_pcpu_ptr((__p)); \
47    RELOC_HIDE((typeof(*(__p)) __kernel __force *)(__p), (__offset)); \
48})
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(&(var), per_cpu_offset(cpu)))
58
59#ifndef __this_cpu_ptr
60#define __this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, __my_cpu_offset)
61#endif
62#ifdef CONFIG_DEBUG_PREEMPT
63#define this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, my_cpu_offset)
64#else
65#define this_cpu_ptr(ptr) __this_cpu_ptr(ptr)
66#endif
67
68#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))
69#define __raw_get_cpu_var(var) (*__this_cpu_ptr(&(var)))
70
71#ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA
72extern void setup_per_cpu_areas(void);
73#endif
74
75#else /* ! SMP */
76
77#define VERIFY_PERCPU_PTR(__p) ({ \
78    __verify_pcpu_ptr((__p)); \
79    (typeof(*(__p)) __kernel __force *)(__p); \
80})
81
82#define per_cpu(var, cpu) (*((void)(cpu), VERIFY_PERCPU_PTR(&(var))))
83#define __get_cpu_var(var) (*VERIFY_PERCPU_PTR(&(var)))
84#define __raw_get_cpu_var(var) (*VERIFY_PERCPU_PTR(&(var)))
85#define this_cpu_ptr(ptr) per_cpu_ptr(ptr, 0)
86#define __this_cpu_ptr(ptr) this_cpu_ptr(ptr)
87
88#endif /* SMP */
89
90#ifndef PER_CPU_BASE_SECTION
91#ifdef CONFIG_SMP
92#define PER_CPU_BASE_SECTION ".data..percpu"
93#else
94#define PER_CPU_BASE_SECTION ".data"
95#endif
96#endif
97
98#ifdef CONFIG_SMP
99
100#ifdef MODULE
101#define PER_CPU_SHARED_ALIGNED_SECTION ""
102#define PER_CPU_ALIGNED_SECTION ""
103#else
104#define PER_CPU_SHARED_ALIGNED_SECTION "..shared_aligned"
105#define PER_CPU_ALIGNED_SECTION "..shared_aligned"
106#endif
107#define PER_CPU_FIRST_SECTION "..first"
108
109#else
110
111#define PER_CPU_SHARED_ALIGNED_SECTION ""
112#define PER_CPU_ALIGNED_SECTION "..shared_aligned"
113#define PER_CPU_FIRST_SECTION ""
114
115#endif
116
117#ifndef PER_CPU_ATTRIBUTES
118#define PER_CPU_ATTRIBUTES
119#endif
120
121#ifndef PER_CPU_DEF_ATTRIBUTES
122#define PER_CPU_DEF_ATTRIBUTES
123#endif
124
125#endif /* _ASM_GENERIC_PERCPU_H_ */
126

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