David Howells | 5028eaa | 2009-04-21 23:00:29 +0100 | [diff] [blame] | 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 |
Tejun Heo | 7c756e6 | 2009-06-24 15:13:50 +0900 | [diff] [blame] | 13 | * 'sec' argument. This may be used to affect the parameters governing the |
David Howells | 5028eaa | 2009-04-21 23:00:29 +0100 | [diff] [blame] | 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 | */ |
Tejun Heo | 7c756e6 | 2009-06-24 15:13:50 +0900 | [diff] [blame] | 20 | #define __PCPU_ATTRS(sec) \ |
| 21 | __attribute__((section(PER_CPU_BASE_SECTION sec))) \ |
| 22 | PER_CPU_ATTRIBUTES |
David Howells | 5028eaa | 2009-04-21 23:00:29 +0100 | [diff] [blame] | 23 | |
Tejun Heo | 7c756e6 | 2009-06-24 15:13:50 +0900 | [diff] [blame] | 24 | #define __PCPU_DUMMY_ATTRS \ |
| 25 | __attribute__((section(".discard"), unused)) |
| 26 | |
| 27 | /* |
| 28 | * s390 and alpha modules require percpu variables to be defined as |
| 29 | * weak to force the compiler to generate GOT based external |
| 30 | * references for them. This is necessary because percpu sections |
| 31 | * will be located outside of the usually addressable area. |
| 32 | * |
| 33 | * This definition puts the following two extra restrictions when |
| 34 | * defining percpu variables. |
| 35 | * |
| 36 | * 1. The symbol must be globally unique, even the static ones. |
| 37 | * 2. Static percpu variables cannot be defined inside a function. |
| 38 | * |
| 39 | * Archs which need weak percpu definitions should define |
| 40 | * ARCH_NEEDS_WEAK_PER_CPU in asm/percpu.h when necessary. |
| 41 | * |
| 42 | * To ensure that the generic code observes the above two |
| 43 | * restrictions, if CONFIG_DEBUG_FORCE_WEAK_PER_CPU is set weak |
| 44 | * definition is used for all cases. |
| 45 | */ |
| 46 | #if defined(ARCH_NEEDS_WEAK_PER_CPU) || defined(CONFIG_DEBUG_FORCE_WEAK_PER_CPU) |
| 47 | /* |
| 48 | * __pcpu_scope_* dummy variable is used to enforce scope. It |
| 49 | * receives the static modifier when it's used in front of |
| 50 | * DEFINE_PER_CPU() and will trigger build failure if |
| 51 | * DECLARE_PER_CPU() is used for the same variable. |
| 52 | * |
| 53 | * __pcpu_unique_* dummy variable is used to enforce symbol uniqueness |
| 54 | * such that hidden weak symbol collision, which will cause unrelated |
| 55 | * variables to share the same address, can be detected during build. |
| 56 | */ |
| 57 | #define DECLARE_PER_CPU_SECTION(type, name, sec) \ |
| 58 | extern __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \ |
Tejun Heo | 1a8dd30 | 2009-06-29 17:45:39 +0900 | [diff] [blame] | 59 | extern __PCPU_ATTRS(sec) __typeof__(type) per_cpu__##name |
Tejun Heo | 7c756e6 | 2009-06-24 15:13:50 +0900 | [diff] [blame] | 60 | |
| 61 | #define DEFINE_PER_CPU_SECTION(type, name, sec) \ |
| 62 | __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \ |
Tejun Heo | 0f5e481 | 2009-10-29 22:34:12 +0900 | [diff] [blame] | 63 | extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ |
Tejun Heo | 7c756e6 | 2009-06-24 15:13:50 +0900 | [diff] [blame] | 64 | __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ |
Tejun Heo | c43768c | 2009-07-04 07:13:18 +0900 | [diff] [blame] | 65 | __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES __weak \ |
Tejun Heo | b01e8dc | 2009-06-30 11:41:18 -0700 | [diff] [blame] | 66 | __typeof__(type) per_cpu__##name |
Tejun Heo | 7c756e6 | 2009-06-24 15:13:50 +0900 | [diff] [blame] | 67 | #else |
| 68 | /* |
| 69 | * Normal declaration and definition macros. |
| 70 | */ |
| 71 | #define DECLARE_PER_CPU_SECTION(type, name, sec) \ |
| 72 | extern __PCPU_ATTRS(sec) __typeof__(type) per_cpu__##name |
| 73 | |
| 74 | #define DEFINE_PER_CPU_SECTION(type, name, sec) \ |
Tejun Heo | c43768c | 2009-07-04 07:13:18 +0900 | [diff] [blame] | 75 | __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES \ |
| 76 | __typeof__(type) per_cpu__##name |
Tejun Heo | 7c756e6 | 2009-06-24 15:13:50 +0900 | [diff] [blame] | 77 | #endif |
David Howells | 5028eaa | 2009-04-21 23:00:29 +0100 | [diff] [blame] | 78 | |
| 79 | /* |
| 80 | * Variant on the per-CPU variable declaration/definition theme used for |
| 81 | * ordinary per-CPU variables. |
| 82 | */ |
| 83 | #define DECLARE_PER_CPU(type, name) \ |
| 84 | DECLARE_PER_CPU_SECTION(type, name, "") |
| 85 | |
| 86 | #define DEFINE_PER_CPU(type, name) \ |
| 87 | DEFINE_PER_CPU_SECTION(type, name, "") |
| 88 | |
| 89 | /* |
| 90 | * Declaration/definition used for per-CPU variables that must come first in |
| 91 | * the set of variables. |
| 92 | */ |
| 93 | #define DECLARE_PER_CPU_FIRST(type, name) \ |
| 94 | DECLARE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION) |
| 95 | |
| 96 | #define DEFINE_PER_CPU_FIRST(type, name) \ |
| 97 | DEFINE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION) |
| 98 | |
| 99 | /* |
| 100 | * Declaration/definition used for per-CPU variables that must be cacheline |
| 101 | * aligned under SMP conditions so that, whilst a particular instance of the |
| 102 | * data corresponds to a particular CPU, inefficiencies due to direct access by |
| 103 | * other CPUs are reduced by preventing the data from unnecessarily spanning |
| 104 | * cachelines. |
| 105 | * |
| 106 | * An example of this would be statistical data, where each CPU's set of data |
| 107 | * is updated by that CPU alone, but the data from across all CPUs is collated |
| 108 | * by a CPU processing a read from a proc file. |
| 109 | */ |
| 110 | #define DECLARE_PER_CPU_SHARED_ALIGNED(type, name) \ |
| 111 | DECLARE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \ |
| 112 | ____cacheline_aligned_in_smp |
| 113 | |
| 114 | #define DEFINE_PER_CPU_SHARED_ALIGNED(type, name) \ |
| 115 | DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \ |
| 116 | ____cacheline_aligned_in_smp |
| 117 | |
Jeremy Fitzhardinge | 53f8245 | 2009-09-03 14:31:44 -0700 | [diff] [blame] | 118 | #define DECLARE_PER_CPU_ALIGNED(type, name) \ |
| 119 | DECLARE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \ |
| 120 | ____cacheline_aligned |
| 121 | |
| 122 | #define DEFINE_PER_CPU_ALIGNED(type, name) \ |
| 123 | DEFINE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \ |
| 124 | ____cacheline_aligned |
| 125 | |
David Howells | 5028eaa | 2009-04-21 23:00:29 +0100 | [diff] [blame] | 126 | /* |
| 127 | * Declaration/definition used for per-CPU variables that must be page aligned. |
| 128 | */ |
Tejun Heo | 3e352aa | 2009-08-03 14:10:11 +0900 | [diff] [blame] | 129 | #define DECLARE_PER_CPU_PAGE_ALIGNED(type, name) \ |
Denys Vlasenko | 3d9a854 | 2010-02-20 01:03:43 +0100 | [diff] [blame^] | 130 | DECLARE_PER_CPU_SECTION(type, name, "..page_aligned") \ |
Tejun Heo | 3e352aa | 2009-08-03 14:10:11 +0900 | [diff] [blame] | 131 | __aligned(PAGE_SIZE) |
David Howells | 5028eaa | 2009-04-21 23:00:29 +0100 | [diff] [blame] | 132 | |
| 133 | #define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \ |
Denys Vlasenko | 3d9a854 | 2010-02-20 01:03:43 +0100 | [diff] [blame^] | 134 | DEFINE_PER_CPU_SECTION(type, name, "..page_aligned") \ |
Tejun Heo | 3e352aa | 2009-08-03 14:10:11 +0900 | [diff] [blame] | 135 | __aligned(PAGE_SIZE) |
David Howells | 5028eaa | 2009-04-21 23:00:29 +0100 | [diff] [blame] | 136 | |
| 137 | /* |
| 138 | * Intermodule exports for per-CPU variables. |
| 139 | */ |
| 140 | #define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(per_cpu__##var) |
| 141 | #define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(per_cpu__##var) |
| 142 | |
| 143 | |
| 144 | #endif /* _LINUX_PERCPU_DEFS_H */ |