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 #define SHIFT_PERCPU_PTR(__p, __offset) RELOC_HIDE((__p), (__offset))
  45 #endif
  46
  47 /*
  48  * A percpu variable may point to a discarded regions. The following are
  49  * established ways to produce a usable pointer from the percpu variable
  50  * offset.
  51  */
  52 #define per_cpu(var, cpu) \
  53         (*SHIFT_PERCPU_PTR(&per_cpu_var(var), per_cpu_offset(cpu)))
  54 #define __get_cpu_var(var) \
  55         (*SHIFT_PERCPU_PTR(&per_cpu_var(var), my_cpu_offset))
  56 #define __raw_get_cpu_var(var) \
  57         (*SHIFT_PERCPU_PTR(&per_cpu_var(var), __my_cpu_offset))
  58
  59
  60 #ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA
  61 extern void setup_per_cpu_areas(void);
  62 #endif
  63
  64 #else /* ! SMP */
  65
  66 #define per_cpu(var, cpu)                       (*((void)(cpu), &per_cpu_var(var)))
  67 #define __get_cpu_var(var)                      per_cpu_var(var)
  68 #define __raw_get_cpu_var(var)                  per_cpu_var(var)
  69
  70 #endif  /* SMP */
  71
  72 #ifndef PER_CPU_BASE_SECTION
  73 #ifdef CONFIG_SMP
  74 #define PER_CPU_BASE_SECTION ".data.percpu"
  75 #else
  76 #define PER_CPU_BASE_SECTION ".data"
  77 #endif
  78 #endif
  79
  80 #ifdef CONFIG_SMP
  81
  82 #ifdef MODULE
  83 #define PER_CPU_SHARED_ALIGNED_SECTION ""
  84 #else
  85 #define PER_CPU_SHARED_ALIGNED_SECTION ".shared_aligned"
  86 #endif
  87 #define PER_CPU_FIRST_SECTION ".first"
  88
  89 #else
  90
  91 #define PER_CPU_SHARED_ALIGNED_SECTION ""
  92 #define PER_CPU_FIRST_SECTION ""
  93
  94 #endif
  95
  96 #ifndef PER_CPU_ATTRIBUTES
  97 #define PER_CPU_ATTRIBUTES
  98 #endif
  99
 100 #ifndef PER_CPU_DEF_ATTRIBUTES
 101 #define PER_CPU_DEF_ATTRIBUTES
 102 #endif
 103
 104 #endif /* _ASM_GENERIC_PERCPU_H_ */