1 #ifndef _ASM_GENERIC_PERCPU_H_ 2 #define _ASM_GENERIC_PERCPU_H_ 3 #include <linux/compiler.h> 4 #include <linux/threads.h> 5 6 /* 7 * Determine the real variable name from the name visible in the 8 * kernel sources. 9 */ 10 #define per_cpu_var(var) per_cpu__##var 11 12 #ifdef CONFIG_SMP 13 14 /* 15 * per_cpu_offset() is the offset that has to be added to a 16 * percpu variable to get to the instance for a certain processor. 17 * 18 * Most arches use the __per_cpu_offset array for those offsets but 19 * some arches have their own ways of determining the offset (x86_64, s390). 20 */ 21 #ifndef __per_cpu_offset 22 extern unsigned long __per_cpu_offset[NR_CPUS]; 23 24 #define per_cpu_offset(x) (__per_cpu_offset[x]) 25 #endif 26 27 /* 28 * Determine the offset for the currently active processor. 29 * An arch may define __my_cpu_offset to provide a more effective 30 * means of obtaining the offset to the per cpu variables of the 31 * current processor. 32 */ 33 #ifndef __my_cpu_offset 34 #define __my_cpu_offset per_cpu_offset(raw_smp_processor_id()) 35 #endif 36 #ifdef CONFIG_DEBUG_PREEMPT 37 #define my_cpu_offset per_cpu_offset(smp_processor_id()) 38 #else 39 #define my_cpu_offset __my_cpu_offset 40 #endif 41 42 /* 43 * Add a offset to a pointer but keep the pointer as is. 44 * 45 * Only S390 provides its own means of moving the pointer. 46 */ 47 #ifndef SHIFT_PERCPU_PTR 48 #define SHIFT_PERCPU_PTR(__p, __offset) RELOC_HIDE((__p), (__offset)) 49 #endif 50 51 /* 52 * A percpu variable may point to a discarded regions. The following are 53 * established ways to produce a usable pointer from the percpu variable 54 * offset. 55 */ 56 #define per_cpu(var, cpu) \ 57 (*SHIFT_PERCPU_PTR(&per_cpu_var(var), per_cpu_offset(cpu))) 58 #define __get_cpu_var(var) \ 59 (*SHIFT_PERCPU_PTR(&per_cpu_var(var), my_cpu_offset)) 60 #define __raw_get_cpu_var(var) \ 61 (*SHIFT_PERCPU_PTR(&per_cpu_var(var), __my_cpu_offset)) 62 63 64 #ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA 65 extern void setup_per_cpu_areas(void); 66 #endif 67 68 #else /* ! SMP */ 69 70 #define per_cpu(var, cpu) (*((void)(cpu), &per_cpu_var(var))) 71 #define __get_cpu_var(var) per_cpu_var(var) 72 #define __raw_get_cpu_var(var) per_cpu_var(var) 73 74 #endif /* SMP */ 75 76 #ifndef PER_CPU_ATTRIBUTES 77 #define PER_CPU_ATTRIBUTES 78 #endif 79 80 #define DECLARE_PER_CPU(type, name) extern PER_CPU_ATTRIBUTES \ 81 __typeof__(type) per_cpu_var(name) 82 83 /* 84 * Optional methods for optimized non-lvalue per-cpu variable access. 85 * 86 * @var can be a percpu variable or a field of it and its size should 87 * equal char, int or long. percpu_read() evaluates to a lvalue and 88 * all others to void. 89 * 90 * These operations are guaranteed to be atomic w.r.t. preemption. 91 * The generic versions use plain get/put_cpu_var(). Archs are 92 * encouraged to implement single-instruction alternatives which don't 93 * require preemption protection. 94 */ 95 #ifndef percpu_read 96 # define percpu_read(var) \ 97 ({ \ 98 typeof(per_cpu_var(var)) __tmp_var__; \ 99 __tmp_var__ = get_cpu_var(var); \ 100 put_cpu_var(var); \ 101 __tmp_var__; \ 102 }) 103 #endif 104 105 #define __percpu_generic_to_op(var, val, op) \ 106 do { \ 107 get_cpu_var(var) op val; \ 108 put_cpu_var(var); \ 109 } while (0) 110 111 #ifndef percpu_write 112 # define percpu_write(var, val) __percpu_generic_to_op(var, (val), =) 113 #endif 114 115 #ifndef percpu_add 116 # define percpu_add(var, val) __percpu_generic_to_op(var, (val), +=) 117 #endif 118 119 #ifndef percpu_sub 120 # define percpu_sub(var, val) __percpu_generic_to_op(var, (val), -=) 121 #endif 122 123 #ifndef percpu_and 124 # define percpu_and(var, val) __percpu_generic_to_op(var, (val), &=) 125 #endif 126 127 #ifndef percpu_or 128 # define percpu_or(var, val) __percpu_generic_to_op(var, (val), |=) 129 #endif 130 131 #ifndef percpu_xor 132 # define percpu_xor(var, val) __percpu_generic_to_op(var, (val), ^=) 133 #endif 134 135 #endif /* _ASM_GENERIC_PERCPU_H_ */ 136