linux/include/asm-generic/percpu.h
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   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
  18extern 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
  59#ifndef __this_cpu_ptr
  60#define __this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, __my_cpu_offset)
  61#endif
  62#ifdef CONFIG_DEBUG_PREEMPT
  63#define this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, my_cpu_offset)
  64#else
  65#define this_cpu_ptr(ptr) __this_cpu_ptr(ptr)
  66#endif
  67
  68#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))
  69#define __raw_get_cpu_var(var) (*__this_cpu_ptr(&(var)))
  70
  71#ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA
  72extern void setup_per_cpu_areas(void);
  73#endif
  74
  75#else /* ! SMP */
  76
  77#define VERIFY_PERCPU_PTR(__p) ({                       \
  78        __verify_pcpu_ptr((__p));                       \
  79        (typeof(*(__p)) __kernel __force *)(__p);       \
  80})
  81
  82#define per_cpu(var, cpu)       (*((void)(cpu), VERIFY_PERCPU_PTR(&(var))))
  83#define __get_cpu_var(var)      (*VERIFY_PERCPU_PTR(&(var)))
  84#define __raw_get_cpu_var(var)  (*VERIFY_PERCPU_PTR(&(var)))
  85#define this_cpu_ptr(ptr)       per_cpu_ptr(ptr, 0)
  86#define __this_cpu_ptr(ptr)     this_cpu_ptr(ptr)
  87
  88#endif  /* SMP */
  89
  90#ifndef PER_CPU_BASE_SECTION
  91#ifdef CONFIG_SMP
  92#define PER_CPU_BASE_SECTION ".data..percpu"
  93#else
  94#define PER_CPU_BASE_SECTION ".data"
  95#endif
  96#endif
  97
  98#ifdef CONFIG_SMP
  99
 100#ifdef MODULE
 101#define PER_CPU_SHARED_ALIGNED_SECTION ""
 102#define PER_CPU_ALIGNED_SECTION ""
 103#else
 104#define PER_CPU_SHARED_ALIGNED_SECTION "..shared_aligned"
 105#define PER_CPU_ALIGNED_SECTION "..shared_aligned"
 106#endif
 107#define PER_CPU_FIRST_SECTION "..first"
 108
 109#else
 110
 111#define PER_CPU_SHARED_ALIGNED_SECTION ""
 112#define PER_CPU_ALIGNED_SECTION "..shared_aligned"
 113#define PER_CPU_FIRST_SECTION ""
 114
 115#endif
 116
 117#ifndef PER_CPU_ATTRIBUTES
 118#define PER_CPU_ATTRIBUTES
 119#endif
 120
 121#ifndef PER_CPU_DEF_ATTRIBUTES
 122#define PER_CPU_DEF_ATTRIBUTES
 123#endif
 124
 125#endif /* _ASM_GENERIC_PERCPU_H_ */
 126
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