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1 | #ifndef _LINUX_PERCPU_DEFS_H |
2 | #define _LINUX_PERCPU_DEFS_H | |
3 | ||
4 | /* | |
5 | * Determine the real variable name from the name visible in the | |
6 | * kernel sources. | |
7 | */ | |
8 | #define per_cpu_var(var) per_cpu__##var | |
9 | ||
10 | /* | |
11 | * Base implementations of per-CPU variable declarations and definitions, where | |
12 | * the section in which the variable is to be placed is provided by the | |
13 | * 'section' argument. This may be used to affect the parameters governing the | |
14 | * variable's storage. | |
15 | * | |
16 | * NOTE! The sections for the DECLARE and for the DEFINE must match, lest | |
17 | * linkage errors occur due the compiler generating the wrong code to access | |
18 | * that section. | |
19 | */ | |
20 | #define DECLARE_PER_CPU_SECTION(type, name, section) \ | |
21 | extern \ | |
22 | __attribute__((__section__(PER_CPU_BASE_SECTION section))) \ | |
23 | PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name | |
24 | ||
25 | #define DEFINE_PER_CPU_SECTION(type, name, section) \ | |
26 | __attribute__((__section__(PER_CPU_BASE_SECTION section))) \ | |
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27 | PER_CPU_ATTRIBUTES PER_CPU_DEF_ATTRIBUTES \ |
28 | __typeof__(type) per_cpu__##name | |
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29 | |
30 | /* | |
31 | * Variant on the per-CPU variable declaration/definition theme used for | |
32 | * ordinary per-CPU variables. | |
33 | */ | |
34 | #define DECLARE_PER_CPU(type, name) \ | |
35 | DECLARE_PER_CPU_SECTION(type, name, "") | |
36 | ||
37 | #define DEFINE_PER_CPU(type, name) \ | |
38 | DEFINE_PER_CPU_SECTION(type, name, "") | |
39 | ||
40 | /* | |
41 | * Declaration/definition used for per-CPU variables that must come first in | |
42 | * the set of variables. | |
43 | */ | |
44 | #define DECLARE_PER_CPU_FIRST(type, name) \ | |
45 | DECLARE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION) | |
46 | ||
47 | #define DEFINE_PER_CPU_FIRST(type, name) \ | |
48 | DEFINE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION) | |
49 | ||
50 | /* | |
51 | * Declaration/definition used for per-CPU variables that must be cacheline | |
52 | * aligned under SMP conditions so that, whilst a particular instance of the | |
53 | * data corresponds to a particular CPU, inefficiencies due to direct access by | |
54 | * other CPUs are reduced by preventing the data from unnecessarily spanning | |
55 | * cachelines. | |
56 | * | |
57 | * An example of this would be statistical data, where each CPU's set of data | |
58 | * is updated by that CPU alone, but the data from across all CPUs is collated | |
59 | * by a CPU processing a read from a proc file. | |
60 | */ | |
61 | #define DECLARE_PER_CPU_SHARED_ALIGNED(type, name) \ | |
62 | DECLARE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \ | |
63 | ____cacheline_aligned_in_smp | |
64 | ||
65 | #define DEFINE_PER_CPU_SHARED_ALIGNED(type, name) \ | |
66 | DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \ | |
67 | ____cacheline_aligned_in_smp | |
68 | ||
69 | /* | |
70 | * Declaration/definition used for per-CPU variables that must be page aligned. | |
71 | */ | |
72 | #define DECLARE_PER_CPU_PAGE_ALIGNED(type, name) \ | |
73 | DECLARE_PER_CPU_SECTION(type, name, ".page_aligned") | |
74 | ||
75 | #define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \ | |
76 | DEFINE_PER_CPU_SECTION(type, name, ".page_aligned") | |
77 | ||
78 | /* | |
79 | * Intermodule exports for per-CPU variables. | |
80 | */ | |
81 | #define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(per_cpu__##var) | |
82 | #define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(per_cpu__##var) | |
83 | ||
84 | ||
85 | #endif /* _LINUX_PERCPU_DEFS_H */ |