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         __verify_pcpu_ptr((__p));                                       \
  47         RELOC_HIDE((typeof(*(__p)) __kernel __force *)(__p), (__offset)); \
  48 })
  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(&(var), per_cpu_offset(cpu)))
  58 #define __get_cpu_var(var) \
  59         (*SHIFT_PERCPU_PTR(&(var), my_cpu_offset))
  60 #define __raw_get_cpu_var(var) \
  61         (*SHIFT_PERCPU_PTR(&(var), __my_cpu_offset))
  62
  63 #define this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, my_cpu_offset)
  64 #define __this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, __my_cpu_offset)
  65
  66
  67 #ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA
  68 extern void setup_per_cpu_areas(void);
  69 #endif
  70
  71 #else /* ! SMP */
  72
  73 #define per_cpu(var, cpu)                       (*((void)(cpu), &(var)))
  74 #define __get_cpu_var(var)                      (var)
  75 #define __raw_get_cpu_var(var)                  (var)
  76 #define this_cpu_ptr(ptr) per_cpu_ptr(ptr, 0)
  77 #define __this_cpu_ptr(ptr) this_cpu_ptr(ptr)
  78
  79 #endif  /* SMP */
  80
  81 #ifndef PER_CPU_BASE_SECTION
  82 #ifdef CONFIG_SMP
  83 #define PER_CPU_BASE_SECTION ".data..percpu"
  84 #else
  85 #define PER_CPU_BASE_SECTION ".data"
  86 #endif
  87 #endif
  88
  89 #ifdef CONFIG_SMP
  90
  91 #ifdef MODULE
  92 #define PER_CPU_SHARED_ALIGNED_SECTION ""
  93 #define PER_CPU_ALIGNED_SECTION ""
  94 #else
  95 #define PER_CPU_SHARED_ALIGNED_SECTION "..shared_aligned"
  96 #define PER_CPU_ALIGNED_SECTION "..shared_aligned"
  97 #endif
  98 #define PER_CPU_FIRST_SECTION "..first"
  99
 100 #else
 101
 102 #define PER_CPU_SHARED_ALIGNED_SECTION ""
 103 #define PER_CPU_ALIGNED_SECTION "..shared_aligned"
 104 #define PER_CPU_FIRST_SECTION ""
 105
 106 #endif
 107
 108 #ifndef PER_CPU_ATTRIBUTES
 109 #define PER_CPU_ATTRIBUTES
 110 #endif
 111
 112 #ifndef PER_CPU_DEF_ATTRIBUTES
 113 #define PER_CPU_DEF_ATTRIBUTES
 114 #endif
 115
 116 #endif /* _ASM_GENERIC_PERCPU_H_ */