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1 | #ifndef _LINUX_PERCPU_DEFS_H |
2 | #define _LINUX_PERCPU_DEFS_H | |
3 | ||
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4 | /* |
5 | * 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 | |
7c756e6e | 7 | * 'sec' argument. This may be used to affect the parameters governing the |
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8 | * 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 | */ | |
7c756e6e | 14 | #define __PCPU_ATTRS(sec) \ |
e0fdb0e0 | 15 | __percpu __attribute__((section(PER_CPU_BASE_SECTION sec))) \ |
7c756e6e TH |
16 | PER_CPU_ATTRIBUTES |
17 | ||
18 | #define __PCPU_DUMMY_ATTRS \ | |
19 | __attribute__((section(".discard"), unused)) | |
20 | ||
545695fb TH |
21 | /* |
22 | * 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 { \ | |
85438592 | 27 | const void __percpu *__vpp_verify = (typeof(ptr))NULL; \ |
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28 | (void)__vpp_verify; \ |
29 | } while (0) | |
30 | ||
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31 | /* |
32 | * 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; \ | |
dd17c8f7 | 63 | extern __PCPU_ATTRS(sec) __typeof__(type) name |
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64 | |
65 | #define DEFINE_PER_CPU_SECTION(type, name, sec) \ | |
66 | __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \ | |
0f5e4816 | 67 | extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ |
7c756e6e | 68 | __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ |
c43768cb | 69 | __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES __weak \ |
dd17c8f7 | 70 | __typeof__(type) name |
7c756e6e TH |
71 | #else |
72 | /* | |
73 | * Normal declaration and definition macros. | |
74 | */ | |
75 | #define DECLARE_PER_CPU_SECTION(type, name, sec) \ | |
dd17c8f7 | 76 | extern __PCPU_ATTRS(sec) __typeof__(type) name |
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77 | |
78 | #define DEFINE_PER_CPU_SECTION(type, name, sec) \ | |
c43768cb | 79 | __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES \ |
dd17c8f7 | 80 | __typeof__(type) name |
7c756e6e | 81 | #endif |
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82 | |
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 | ||
53f82452 JF |
122 | #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 | ||
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130 | /* |
131 | * Declaration/definition used for per-CPU variables that must be page aligned. | |
132 | */ | |
3e352aa8 | 133 | #define DECLARE_PER_CPU_PAGE_ALIGNED(type, name) \ |
3d9a854c | 134 | DECLARE_PER_CPU_SECTION(type, name, "..page_aligned") \ |
3e352aa8 | 135 | __aligned(PAGE_SIZE) |
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136 | |
137 | #define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \ | |
3d9a854c | 138 | DEFINE_PER_CPU_SECTION(type, name, "..page_aligned") \ |
3e352aa8 | 139 | __aligned(PAGE_SIZE) |
5028eaa9 | 140 | |
c957ef2c SL |
141 | /* |
142 | * Declaration/definition used for per-CPU variables that must be read mostly. | |
143 | */ | |
144 | #define DECLARE_PER_CPU_READ_MOSTLY(type, name) \ | |
145 | DECLARE_PER_CPU_SECTION(type, name, "..readmostly") | |
146 | ||
147 | #define DEFINE_PER_CPU_READ_MOSTLY(type, name) \ | |
148 | DEFINE_PER_CPU_SECTION(type, name, "..readmostly") | |
149 | ||
5028eaa9 | 150 | /* |
545695fb TH |
151 | * Intermodule exports for per-CPU variables. sparse forgets about |
152 | * address space across EXPORT_SYMBOL(), change EXPORT_SYMBOL() to | |
153 | * noop if __CHECKER__. | |
5028eaa9 | 154 | */ |
545695fb | 155 | #ifndef __CHECKER__ |
dd17c8f7 RR |
156 | #define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(var) |
157 | #define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(var) | |
545695fb TH |
158 | #else |
159 | #define EXPORT_PER_CPU_SYMBOL(var) | |
160 | #define EXPORT_PER_CPU_SYMBOL_GPL(var) | |
161 | #endif | |
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162 | |
163 | #endif /* _LINUX_PERCPU_DEFS_H */ |