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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef _ASM_GENERIC_PERCPU_H_
2#define _ASM_GENERIC_PERCPU_H_
David Howells5028eaa2009-04-21 23:00:29 +01003
Linus Torvalds1da177e2005-04-16 15:20:36 -07004#include <linux/compiler.h>
Rusty Russellae1ee112007-05-02 19:27:10 +02005#include <linux/threads.h>
David Howells5028eaa2009-04-21 23:00:29 +01006#include <linux/percpu-defs.h>
travis@sgi.comacdac872008-01-30 13:32:52 +01007
Linus Torvalds1da177e2005-04-16 15:20:36 -07008#ifdef CONFIG_SMP
9
travis@sgi.comacdac872008-01-30 13:32:52 +010010/*
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
Linus Torvalds1da177e2005-04-16 15:20:36 -070018extern unsigned long __per_cpu_offset[NR_CPUS];
19
Ingo Molnara875a692006-07-03 00:24:26 -070020#define per_cpu_offset(x) (__per_cpu_offset[x])
travis@sgi.comacdac872008-01-30 13:32:52 +010021#endif
Ingo Molnara875a692006-07-03 00:24:26 -070022
travis@sgi.comacdac872008-01-30 13:32:52 +010023/*
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())
Hugh Dickins1e835272008-02-23 19:40:17 +000031#endif
32#ifdef CONFIG_DEBUG_PREEMPT
travis@sgi.comacdac872008-01-30 13:32:52 +010033#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#define SHIFT_PERCPU_PTR(__p, __offset) RELOC_HIDE((__p), (__offset))
45#endif
46
47/*
Mike Travisdd5af902008-01-30 13:33:32 +010048 * A percpu variable may point to a discarded regions. The following are
travis@sgi.comacdac872008-01-30 13:32:52 +010049 * established ways to produce a usable pointer from the percpu variable
50 * offset.
51 */
52#define per_cpu(var, cpu) \
53 (*SHIFT_PERCPU_PTR(&per_cpu_var(var), per_cpu_offset(cpu)))
54#define __get_cpu_var(var) \
55 (*SHIFT_PERCPU_PTR(&per_cpu_var(var), my_cpu_offset))
56#define __raw_get_cpu_var(var) \
57 (*SHIFT_PERCPU_PTR(&per_cpu_var(var), __my_cpu_offset))
58
59
Mike Travisdd5af902008-01-30 13:33:32 +010060#ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA
travis@sgi.comacdac872008-01-30 13:32:52 +010061extern void setup_per_cpu_areas(void);
62#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070063
Linus Torvalds1da177e2005-04-16 15:20:36 -070064#else /* ! SMP */
65
travis@sgi.comacdac872008-01-30 13:32:52 +010066#define per_cpu(var, cpu) (*((void)(cpu), &per_cpu_var(var)))
67#define __get_cpu_var(var) per_cpu_var(var)
68#define __raw_get_cpu_var(var) per_cpu_var(var)
Linus Torvalds1da177e2005-04-16 15:20:36 -070069
70#endif /* SMP */
71
David Howells9b8de742009-04-21 23:00:24 +010072#ifndef PER_CPU_BASE_SECTION
73#ifdef CONFIG_SMP
74#define PER_CPU_BASE_SECTION ".data.percpu"
75#else
76#define PER_CPU_BASE_SECTION ".data"
77#endif
78#endif
79
80#ifdef CONFIG_SMP
81
82#ifdef MODULE
83#define PER_CPU_SHARED_ALIGNED_SECTION ""
84#else
85#define PER_CPU_SHARED_ALIGNED_SECTION ".shared_aligned"
86#endif
87#define PER_CPU_FIRST_SECTION ".first"
88
89#else
90
91#define PER_CPU_SHARED_ALIGNED_SECTION ""
92#define PER_CPU_FIRST_SECTION ""
93
94#endif
95
travis@sgi.comacdac872008-01-30 13:32:52 +010096#ifndef PER_CPU_ATTRIBUTES
97#define PER_CPU_ATTRIBUTES
98#endif
99
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100#endif /* _ASM_GENERIC_PERCPU_H_ */