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 */ 86