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David Howells5028eaa2009-04-21 23:00:29 +01001#ifndef _LINUX_PERCPU_DEFS_H
2#define _LINUX_PERCPU_DEFS_H
3
4/*
David Howells5028eaa2009-04-21 23:00:29 +01005 * Base implementations of per-CPU variable declarations and definitions, where
6 * the section in which the variable is to be placed is provided by the
Tejun Heo7c756e62009-06-24 15:13:50 +09007 * 'sec' argument. This may be used to affect the parameters governing the
David Howells5028eaa2009-04-21 23:00:29 +01008 * variable's storage.
9 *
10 * NOTE! The sections for the DECLARE and for the DEFINE must match, lest
11 * linkage errors occur due the compiler generating the wrong code to access
12 * that section.
13 */
Tejun Heo7c756e62009-06-24 15:13:50 +090014#define __PCPU_ATTRS(sec) \
Rusty Russelle0fdb0e2009-10-29 22:34:15 +090015 __percpu __attribute__((section(PER_CPU_BASE_SECTION sec))) \
Tejun Heo7c756e62009-06-24 15:13:50 +090016 PER_CPU_ATTRIBUTES
David Howells5028eaa2009-04-21 23:00:29 +010017
Tejun Heo7c756e62009-06-24 15:13:50 +090018#define __PCPU_DUMMY_ATTRS \
19 __attribute__((section(".discard"), unused))
20
21/*
Tejun Heo545695f2009-10-29 22:34:15 +090022 * Macro which verifies @ptr is a percpu pointer without evaluating
23 * @ptr. This is to be used in percpu accessors to verify that the
24 * input parameter is a percpu pointer.
25 */
26#define __verify_pcpu_ptr(ptr) do { \
Tejun Heo85438592009-11-18 17:53:21 +090027 const void __percpu *__vpp_verify = (typeof(ptr))NULL; \
Tejun Heo545695f2009-10-29 22:34:15 +090028 (void)__vpp_verify; \
29} while (0)
30
31/*
Tejun Heo7c756e62009-06-24 15:13:50 +090032 * s390 and alpha modules require percpu variables to be defined as
33 * weak to force the compiler to generate GOT based external
34 * references for them. This is necessary because percpu sections
35 * will be located outside of the usually addressable area.
36 *
37 * This definition puts the following two extra restrictions when
38 * defining percpu variables.
39 *
40 * 1. The symbol must be globally unique, even the static ones.
41 * 2. Static percpu variables cannot be defined inside a function.
42 *
43 * Archs which need weak percpu definitions should define
44 * ARCH_NEEDS_WEAK_PER_CPU in asm/percpu.h when necessary.
45 *
46 * To ensure that the generic code observes the above two
47 * restrictions, if CONFIG_DEBUG_FORCE_WEAK_PER_CPU is set weak
48 * definition is used for all cases.
49 */
50#if defined(ARCH_NEEDS_WEAK_PER_CPU) || defined(CONFIG_DEBUG_FORCE_WEAK_PER_CPU)
51/*
52 * __pcpu_scope_* dummy variable is used to enforce scope. It
53 * receives the static modifier when it's used in front of
54 * DEFINE_PER_CPU() and will trigger build failure if
55 * DECLARE_PER_CPU() is used for the same variable.
56 *
57 * __pcpu_unique_* dummy variable is used to enforce symbol uniqueness
58 * such that hidden weak symbol collision, which will cause unrelated
59 * variables to share the same address, can be detected during build.
60 */
61#define DECLARE_PER_CPU_SECTION(type, name, sec) \
62 extern __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \
Rusty Russelldd17c8f2009-10-29 22:34:15 +090063 extern __PCPU_ATTRS(sec) __typeof__(type) name
Tejun Heo7c756e62009-06-24 15:13:50 +090064
65#define DEFINE_PER_CPU_SECTION(type, name, sec) \
66 __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \
Tejun Heo0f5e4812009-10-29 22:34:12 +090067 extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \
Tejun Heo7c756e62009-06-24 15:13:50 +090068 __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \
Tejun Heoc43768c2009-07-04 07:13:18 +090069 __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES __weak \
Rusty Russelldd17c8f2009-10-29 22:34:15 +090070 __typeof__(type) name
Tejun Heo7c756e62009-06-24 15:13:50 +090071#else
72/*
73 * Normal declaration and definition macros.
74 */
75#define DECLARE_PER_CPU_SECTION(type, name, sec) \
Rusty Russelldd17c8f2009-10-29 22:34:15 +090076 extern __PCPU_ATTRS(sec) __typeof__(type) name
Tejun Heo7c756e62009-06-24 15:13:50 +090077
78#define DEFINE_PER_CPU_SECTION(type, name, sec) \
Tejun Heoc43768c2009-07-04 07:13:18 +090079 __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES \
Rusty Russelldd17c8f2009-10-29 22:34:15 +090080 __typeof__(type) name
Tejun Heo7c756e62009-06-24 15:13:50 +090081#endif
David Howells5028eaa2009-04-21 23:00:29 +010082
83/*
84 * Variant on the per-CPU variable declaration/definition theme used for
85 * ordinary per-CPU variables.
86 */
87#define DECLARE_PER_CPU(type, name) \
88 DECLARE_PER_CPU_SECTION(type, name, "")
89
90#define DEFINE_PER_CPU(type, name) \
91 DEFINE_PER_CPU_SECTION(type, name, "")
92
93/*
94 * Declaration/definition used for per-CPU variables that must come first in
95 * the set of variables.
96 */
97#define DECLARE_PER_CPU_FIRST(type, name) \
98 DECLARE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
99
100#define DEFINE_PER_CPU_FIRST(type, name) \
101 DEFINE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
102
103/*
104 * Declaration/definition used for per-CPU variables that must be cacheline
105 * aligned under SMP conditions so that, whilst a particular instance of the
106 * data corresponds to a particular CPU, inefficiencies due to direct access by
107 * other CPUs are reduced by preventing the data from unnecessarily spanning
108 * cachelines.
109 *
110 * An example of this would be statistical data, where each CPU's set of data
111 * is updated by that CPU alone, but the data from across all CPUs is collated
112 * by a CPU processing a read from a proc file.
113 */
114#define DECLARE_PER_CPU_SHARED_ALIGNED(type, name) \
115 DECLARE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
116 ____cacheline_aligned_in_smp
117
118#define DEFINE_PER_CPU_SHARED_ALIGNED(type, name) \
119 DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
120 ____cacheline_aligned_in_smp
121
Jeremy Fitzhardinge53f82452009-09-03 14:31:44 -0700122#define DECLARE_PER_CPU_ALIGNED(type, name) \
123 DECLARE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \
124 ____cacheline_aligned
125
126#define DEFINE_PER_CPU_ALIGNED(type, name) \
127 DEFINE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \
128 ____cacheline_aligned
129
David Howells5028eaa2009-04-21 23:00:29 +0100130/*
131 * Declaration/definition used for per-CPU variables that must be page aligned.
132 */
Tejun Heo3e352aa2009-08-03 14:10:11 +0900133#define DECLARE_PER_CPU_PAGE_ALIGNED(type, name) \
134 DECLARE_PER_CPU_SECTION(type, name, ".page_aligned") \
135 __aligned(PAGE_SIZE)
David Howells5028eaa2009-04-21 23:00:29 +0100136
137#define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \
Tejun Heo3e352aa2009-08-03 14:10:11 +0900138 DEFINE_PER_CPU_SECTION(type, name, ".page_aligned") \
139 __aligned(PAGE_SIZE)
David Howells5028eaa2009-04-21 23:00:29 +0100140
141/*
Tejun Heo545695f2009-10-29 22:34:15 +0900142 * Intermodule exports for per-CPU variables. sparse forgets about
143 * address space across EXPORT_SYMBOL(), change EXPORT_SYMBOL() to
144 * noop if __CHECKER__.
David Howells5028eaa2009-04-21 23:00:29 +0100145 */
Tejun Heo545695f2009-10-29 22:34:15 +0900146#ifndef __CHECKER__
Rusty Russelldd17c8f2009-10-29 22:34:15 +0900147#define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(var)
148#define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(var)
Tejun Heo545695f2009-10-29 22:34:15 +0900149#else
150#define EXPORT_PER_CPU_SYMBOL(var)
151#define EXPORT_PER_CPU_SYMBOL_GPL(var)
152#endif
David Howells5028eaa2009-04-21 23:00:29 +0100153
154#endif /* _LINUX_PERCPU_DEFS_H */