kern/include/percpu.h

   1 /* Copyright (c) 2015 Google Inc
   2  * Davide Libenzi <dlibenzi@google.com>
   3  * See LICENSE for details.
   4  *
   5  * The per CPU utility macros allow file local declaration of per CPU variables.
   6  * When a struct my_struct needs to have a per CPU instance, one would declare
   7  * something like:
   8  *
   9  *   static DEFINE_PERCPU(struct my_struct, my_data);
  10  *
  11  * The per CPU data can then be accessed with either of those forms:
  12  *
  13  *   struct my_struct *ptr = PERCPU_VARPTR(my_data);
  14  *   PERCPU_VAR(my_data).field = 17;
  15  *
  16  * When the per CPU data has complex initialization, it is possible to register
  17  * functions which will be called immediately after the per CPU data is created:
  18  *
  19  *   DEFINE_PERCPU_INIT(my_init);
  20  *
  21  * Then the my_init() function would just:
  22  *
  23  *   static void my_init(void)
  24  *   {
  25  *       for (int i = 0; i < num_cores; i++) {
  26  *           struct my_struct *ptr = _PERCPU_VARPTR(my_data, i);
  27  *
  28  *           // Initialize ptr data
  29  *       }
  30  *   }
  31  */
  32
  33 #pragma once
  34
  35 #include <sys/types.h>
  36 #include <arch/topology.h>
  37 #include <ros/common.h>
  38
  39 #define PERCPU_SECTION __percpu
  40 #define PERCPU_SECTION_STR STRINGIFY(PERCPU_SECTION)
  41
  42 #define PASTE_THEM(x, y) x ## y
  43 #define PASTE(x, y) PASTE_THEM(x, y)
  44
  45 #define PERCPU_VARNAME(var) PASTE(__percpu_, var)
  46
  47 #define PERCPU_START_VAR PASTE(__start_, PERCPU_SECTION)
  48 #define PERCPU_STOP_VAR PASTE(__stop_, PERCPU_SECTION)
  49
  50 #define PERCPU_SIZE (PERCPU_STOP_VAR - PERCPU_START_VAR)
  51 #define PERCPU_OFFSET(var) ((char *) &(var) - PERCPU_START_VAR)
  52
  53 #define __PERCPU_VARPTR(var, cpu)                                                                               \
  54         ({                                                                                                                                      \
  55                 typeof(var) *__cv;                                                                                              \
  56                 if (likely(percpu_base))                                                                                \
  57                         __cv = (typeof(var) *) (percpu_base + cpu * PERCPU_SIZE +       \
  58                                                     PERCPU_OFFSET(var));                                \
  59                 else                                                                                                                    \
  60                         __cv = &var;                                                                                            \
  61                 __cv;                                                                                                                   \
  62         })
  63 #define _PERCPU_VARPTR(var, cpu) __PERCPU_VARPTR(PERCPU_VARNAME(var), cpu)
  64 #define PERCPU_VARPTR(var) __PERCPU_VARPTR(PERCPU_VARNAME(var), core_id())
  65
  66 #define _PERCPU_VAR(var, cpu) (*__PERCPU_VARPTR(PERCPU_VARNAME(var), cpu))
  67 #define PERCPU_VAR(var) (*__PERCPU_VARPTR(PERCPU_VARNAME(var), core_id()))
  68
  69 #define DEFINE_PERCPU(type, var)                                                \
  70         type PERCPU_VARNAME(var) __attribute__ ((section (PERCPU_SECTION_STR)))
  71 #define DECLARE_PERCPU(type, var)                                                               \
  72         extern type PERCPU_VARNAME(var)                                                         \
  73                 __attribute__ ((section (PERCPU_SECTION_STR)))
  74
  75 #define PERCPU_INIT_SECTION __percpu_init
  76 #define PERCPU_INIT_SECTION_STR STRINGIFY(PERCPU_INIT_SECTION)
  77
  78 #define PERCPU_INIT_START_VAR PASTE(__start_, PERCPU_INIT_SECTION)
  79 #define PERCPU_INIT_STOP_VAR PASTE(__stop_, PERCPU_INIT_SECTION)
  80
  81 #define DEFINE_PERCPU_INIT(func)                                                                                \
  82         static void func(void);                                                                                         \
  83         void (* const PERCPU_VARNAME(func))(void)                                                       \
  84                 __attribute__ ((section (PERCPU_INIT_SECTION_STR))) = (func)
  85
  86 extern char __attribute__((weak)) PERCPU_START_VAR[];
  87 extern char __attribute__((weak)) PERCPU_STOP_VAR[];
  88 extern char *percpu_base;
  89
  90 void percpu_init(void);