include/asm-alpha/percpu.h

   1 #ifndef __ALPHA_PERCPU_H
   2 #define __ALPHA_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 extern unsigned long __per_cpu_offset[NR_CPUS];
  19
  20 #define per_cpu_offset(x) (__per_cpu_offset[x])
  21
  22 #define __my_cpu_offset per_cpu_offset(raw_smp_processor_id())
  23 #ifdef CONFIG_DEBUG_PREEMPT
  24 #define my_cpu_offset per_cpu_offset(smp_processor_id())
  25 #else
  26 #define my_cpu_offset __my_cpu_offset
  27 #endif
  28
  29 #ifndef MODULE
  30 #define SHIFT_PERCPU_PTR(var, offset) RELOC_HIDE(&per_cpu_var(var), (offset))
  31 #define PER_CPU_ATTRIBUTES
  32 #else
  33 /*
  34  * To calculate addresses of locally defined variables, GCC uses 32-bit
  35  * displacement from the GP. Which doesn't work for per cpu variables in
  36  * modules, as an offset to the kernel per cpu area is way above 4G.
  37  *
  38  * This forces allocation of a GOT entry for per cpu variable using
  39  * ldq instruction with a 'literal' relocation.
  40  */
  41 #define SHIFT_PERCPU_PTR(var, offset) ({                \
  42         extern int simple_identifier_##var(void);       \
  43         unsigned long __ptr, tmp_gp;                    \
  44         asm (  "br      %1, 1f                        \n\
  45         1:      ldgp    %1, 0(%1)                     \n\
  46                 ldq %0, per_cpu__" #var"(%1)\t!literal"         \
  47                 : "=&r"(__ptr), "=&r"(tmp_gp));         \
  48         (typeof(&per_cpu_var(var)))(__ptr + (offset)); })
  49
  50 #define PER_CPU_ATTRIBUTES      __used
  51
  52 #endif /* MODULE */
  53
  54 /*
  55  * A percpu variable may point to a discarded regions. The following are
  56  * established ways to produce a usable pointer from the percpu variable
  57  * offset.
  58  */
  59 #define per_cpu(var, cpu) \
  60         (*SHIFT_PERCPU_PTR(var, per_cpu_offset(cpu)))
  61 #define __get_cpu_var(var) \
  62         (*SHIFT_PERCPU_PTR(var, my_cpu_offset))
  63 #define __raw_get_cpu_var(var) \
  64         (*SHIFT_PERCPU_PTR(var, __my_cpu_offset))
  65
  66 #else /* ! SMP */
  67
  68 #define per_cpu(var, cpu)               (*((void)(cpu), &per_cpu_var(var)))
  69 #define __get_cpu_var(var)              per_cpu_var(var)
  70 #define __raw_get_cpu_var(var)          per_cpu_var(var)
  71
  72 #define PER_CPU_ATTRIBUTES
  73
  74 #endif /* SMP */
  75
  76 #define DECLARE_PER_CPU(type, name) extern __typeof__(type) per_cpu_var(name)
  77
  78 #endif /* __ALPHA_PERCPU_H */