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 | /* |
David Howells | 5028eaa | 2009-04-21 23:00:29 +0100 | [diff] [blame] | 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 |
Tejun Heo | 7c756e6 | 2009-06-24 15:13:50 +0900 | [diff] [blame] | 7 | * 'sec' argument. This may be used to affect the parameters governing the |
David Howells | 5028eaa | 2009-04-21 23:00:29 +0100 | [diff] [blame] | 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 | */ |
Tejun Heo | 7c756e6 | 2009-06-24 15:13:50 +0900 | [diff] [blame] | 14 | #define __PCPU_ATTRS(sec) \ |
Rusty Russell | e0fdb0e | 2009-10-29 22:34:15 +0900 | [diff] [blame] | 15 | __percpu __attribute__((section(PER_CPU_BASE_SECTION sec))) \ |
Tejun Heo | 7c756e6 | 2009-06-24 15:13:50 +0900 | [diff] [blame] | 16 | PER_CPU_ATTRIBUTES |
David Howells | 5028eaa | 2009-04-21 23:00:29 +0100 | [diff] [blame] | 17 | |
Tejun Heo | 7c756e6 | 2009-06-24 15:13:50 +0900 | [diff] [blame] | 18 | #define __PCPU_DUMMY_ATTRS \ |
| 19 | __attribute__((section(".discard"), unused)) |
| 20 | |
| 21 | /* |
Tejun Heo | 545695f | 2009-10-29 22:34:15 +0900 | [diff] [blame] | 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 { \ |
Tejun Heo | 8543859 | 2009-11-18 17:53:21 +0900 | [diff] [blame] | 27 | const void __percpu *__vpp_verify = (typeof(ptr))NULL; \ |
Tejun Heo | 545695f | 2009-10-29 22:34:15 +0900 | [diff] [blame] | 28 | (void)__vpp_verify; \ |
| 29 | } while (0) |
| 30 | |
| 31 | /* |
Tejun Heo | 7c756e6 | 2009-06-24 15:13:50 +0900 | [diff] [blame] | 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; \ |
Rusty Russell | dd17c8f | 2009-10-29 22:34:15 +0900 | [diff] [blame] | 63 | extern __PCPU_ATTRS(sec) __typeof__(type) name |
Tejun Heo | 7c756e6 | 2009-06-24 15:13:50 +0900 | [diff] [blame] | 64 | |
| 65 | #define DEFINE_PER_CPU_SECTION(type, name, sec) \ |
| 66 | __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \ |
Tejun Heo | 0f5e481 | 2009-10-29 22:34:12 +0900 | [diff] [blame] | 67 | extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ |
Tejun Heo | 7c756e6 | 2009-06-24 15:13:50 +0900 | [diff] [blame] | 68 | __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ |
Tejun Heo | c43768c | 2009-07-04 07:13:18 +0900 | [diff] [blame] | 69 | __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES __weak \ |
Rusty Russell | dd17c8f | 2009-10-29 22:34:15 +0900 | [diff] [blame] | 70 | __typeof__(type) name |
Tejun Heo | 7c756e6 | 2009-06-24 15:13:50 +0900 | [diff] [blame] | 71 | #else |
| 72 | /* |
| 73 | * Normal declaration and definition macros. |
| 74 | */ |
| 75 | #define DECLARE_PER_CPU_SECTION(type, name, sec) \ |
Rusty Russell | dd17c8f | 2009-10-29 22:34:15 +0900 | [diff] [blame] | 76 | extern __PCPU_ATTRS(sec) __typeof__(type) name |
Tejun Heo | 7c756e6 | 2009-06-24 15:13:50 +0900 | [diff] [blame] | 77 | |
| 78 | #define DEFINE_PER_CPU_SECTION(type, name, sec) \ |
Tejun Heo | c43768c | 2009-07-04 07:13:18 +0900 | [diff] [blame] | 79 | __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES \ |
Rusty Russell | dd17c8f | 2009-10-29 22:34:15 +0900 | [diff] [blame] | 80 | __typeof__(type) name |
Tejun Heo | 7c756e6 | 2009-06-24 15:13:50 +0900 | [diff] [blame] | 81 | #endif |
David Howells | 5028eaa | 2009-04-21 23:00:29 +0100 | [diff] [blame] | 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 | |
Jeremy Fitzhardinge | 53f8245 | 2009-09-03 14:31:44 -0700 | [diff] [blame] | 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 | |
David Howells | 5028eaa | 2009-04-21 23:00:29 +0100 | [diff] [blame] | 130 | /* |
| 131 | * Declaration/definition used for per-CPU variables that must be page aligned. |
| 132 | */ |
Tejun Heo | 3e352aa | 2009-08-03 14:10:11 +0900 | [diff] [blame] | 133 | #define DECLARE_PER_CPU_PAGE_ALIGNED(type, name) \ |
Denys Vlasenko | 3d9a854 | 2010-02-20 01:03:43 +0100 | [diff] [blame] | 134 | DECLARE_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 | #define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \ |
Denys Vlasenko | 3d9a854 | 2010-02-20 01:03:43 +0100 | [diff] [blame] | 138 | DEFINE_PER_CPU_SECTION(type, name, "..page_aligned") \ |
Tejun Heo | 3e352aa | 2009-08-03 14:10:11 +0900 | [diff] [blame] | 139 | __aligned(PAGE_SIZE) |
David Howells | 5028eaa | 2009-04-21 23:00:29 +0100 | [diff] [blame] | 140 | |
| 141 | /* |
Shaohua Li | c957ef2 | 2010-10-20 11:07:02 +0800 | [diff] [blame^] | 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 | |
| 150 | /* |
Tejun Heo | 545695f | 2009-10-29 22:34:15 +0900 | [diff] [blame] | 151 | * Intermodule exports for per-CPU variables. sparse forgets about |
| 152 | * address space across EXPORT_SYMBOL(), change EXPORT_SYMBOL() to |
| 153 | * noop if __CHECKER__. |
David Howells | 5028eaa | 2009-04-21 23:00:29 +0100 | [diff] [blame] | 154 | */ |
Tejun Heo | 545695f | 2009-10-29 22:34:15 +0900 | [diff] [blame] | 155 | #ifndef __CHECKER__ |
Rusty Russell | dd17c8f | 2009-10-29 22:34:15 +0900 | [diff] [blame] | 156 | #define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(var) |
| 157 | #define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(var) |
Tejun Heo | 545695f | 2009-10-29 22:34:15 +0900 | [diff] [blame] | 158 | #else |
| 159 | #define EXPORT_PER_CPU_SYMBOL(var) |
| 160 | #define EXPORT_PER_CPU_SYMBOL_GPL(var) |
| 161 | #endif |
David Howells | 5028eaa | 2009-04-21 23:00:29 +0100 | [diff] [blame] | 162 | |
| 163 | #endif /* _LINUX_PERCPU_DEFS_H */ |