include/asm-generic/percpu.h

   1 #ifndef _ASM_GENERIC_PERCPU_H_
   2 #define _ASM_GENERIC_PERCPU_H_
   3
   4 #include <linux/compiler.h>
   5 #include <linux/threads.h>
   6 #include <linux/percpu-defs.h>
   7
   8 #ifdef CONFIG_SMP
   9
  10 /*
  11  * per_cpu_offset() is the offset that has to be added to a
  12  * percpu variable to get to the instance for a certain processor.
  13  *
  14  * Most arches use the __per_cpu_offset array for those offsets but
  15  * some arches have their own ways of determining the offset (x86_64, s390).
  16  */
  17 #ifndef __per_cpu_offset
  18 extern unsigned long __per_cpu_offset[NR_CPUS];
  19
  20 #define per_cpu_offset(x) (__per_cpu_offset[x])
  21 #endif
  22
  23 /*
  24  * Determine the offset for the currently active processor.
  25  * An arch may define __my_cpu_offset to provide a more effective
  26  * means of obtaining the offset to the per cpu variables of the
  27  * current processor.
  28  */
  29 #ifndef __my_cpu_offset
  30 #define __my_cpu_offset per_cpu_offset(raw_smp_processor_id())
  31 #endif
  32 #ifdef CONFIG_DEBUG_PREEMPT
  33 #define my_cpu_offset per_cpu_offset(smp_processor_id())
  34 #else
  35 #define my_cpu_offset __my_cpu_offset
  36 #endif
  37
  38 /*
  39  * Add a offset to a pointer but keep the pointer as is.
  40  *
  41  * Only S390 provides its own means of moving the pointer.
  42  */
  43 #ifndef SHIFT_PERCPU_PTR
  44 /* Weird cast keeps both GCC and sparse happy. */
  45 #define SHIFT_PERCPU_PTR(__p, __offset)                         \
  46         RELOC_HIDE((typeof(*(__p)) __kernel __force *)(__p), (__offset))
  47 #endif
  48
  49 /*
  50  * A percpu variable may point to a discarded regions. The following are
  51  * established ways to produce a usable pointer from the percpu variable
  52  * offset.
  53  */
  54 #define per_cpu(var, cpu) \
  55         (*SHIFT_PERCPU_PTR(&(var), per_cpu_offset(cpu)))
  56 #define __get_cpu_var(var) \
  57         (*SHIFT_PERCPU_PTR(&(var), my_cpu_offset))
  58 #define __raw_get_cpu_var(var) \
  59         (*SHIFT_PERCPU_PTR(&(var), __my_cpu_offset))
  60
  61 #define this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, my_cpu_offset)
  62 #define __this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, __my_cpu_offset)
  63
  64
  65 #ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA
  66 extern void setup_per_cpu_areas(void);
  67 #endif
  68
  69 #else /* ! SMP */
  70
  71 #define per_cpu(var, cpu)                       (*((void)(cpu), &(var)))
  72 #define __get_cpu_var(var)                      (var)
  73 #define __raw_get_cpu_var(var)                  (var)
  74 #define this_cpu_ptr(ptr) per_cpu_ptr(ptr, 0)
  75 #define __this_cpu_ptr(ptr) this_cpu_ptr(ptr)
  76
  77 #endif  /* SMP */
  78
  79 #ifndef PER_CPU_BASE_SECTION
  80 #ifdef CONFIG_SMP
  81 #define PER_CPU_BASE_SECTION ".data.percpu"
  82 #else
  83 #define PER_CPU_BASE_SECTION ".data"
  84 #endif
  85 #endif
  86
  87 #ifdef CONFIG_SMP
  88
  89 #ifdef MODULE
  90 #define PER_CPU_SHARED_ALIGNED_SECTION ""
  91 #define PER_CPU_ALIGNED_SECTION ""
  92 #else
  93 #define PER_CPU_SHARED_ALIGNED_SECTION ".shared_aligned"
  94 #define PER_CPU_ALIGNED_SECTION ".shared_aligned"
  95 #endif
  96 #define PER_CPU_FIRST_SECTION ".first"
  97
  98 #else
  99
 100 #define PER_CPU_SHARED_ALIGNED_SECTION ""
 101 #define PER_CPU_ALIGNED_SECTION ".shared_aligned"
 102 #define PER_CPU_FIRST_SECTION ""
 103
 104 #endif
 105
 106 #ifndef PER_CPU_ATTRIBUTES
 107 #define PER_CPU_ATTRIBUTES
 108 #endif
 109
 110 #ifndef PER_CPU_DEF_ATTRIBUTES
 111 #define PER_CPU_DEF_ATTRIBUTES
 112 #endif
 113
 114 #endif /* _ASM_GENERIC_PERCPU_H_ */