Linux kernel mirror (for testing)
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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))) \
27 PER_CPU_ATTRIBUTES PER_CPU_DEF_ATTRIBUTES \
28 __typeof__(type) per_cpu__##name
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 */