arch/x86/include/asm/percpu.h

   1 #ifndef _ASM_X86_PERCPU_H
   2 #define _ASM_X86_PERCPU_H
   3
   4 #ifdef CONFIG_X86_64
   5 #define __percpu_seg            gs
   6 #define __percpu_mov_op         movq
   7 #else
   8 #define __percpu_seg            fs
   9 #define __percpu_mov_op         movl
  10 #endif
  11
  12 #ifdef __ASSEMBLY__
  13
  14 /*
  15  * PER_CPU finds an address of a per-cpu variable.
  16  *
  17  * Args:
  18  *    var - variable name
  19  *    reg - 32bit register
  20  *
  21  * The resulting address is stored in the "reg" argument.
  22  *
  23  * Example:
  24  *    PER_CPU(cpu_gdt_descr, %ebx)
  25  */
  26 #ifdef CONFIG_SMP
  27 #define PER_CPU(var, reg)                                               \
  28         __percpu_mov_op %__percpu_seg:per_cpu__this_cpu_off, reg;       \
  29         lea per_cpu__##var(reg), reg
  30 #define PER_CPU_VAR(var)        %__percpu_seg:per_cpu__##var
  31 #else /* ! SMP */
  32 #define PER_CPU(var, reg)                                               \
  33         __percpu_mov_op $per_cpu__##var, reg
  34 #define PER_CPU_VAR(var)        per_cpu__##var
  35 #endif  /* SMP */
  36
  37 #ifdef CONFIG_X86_64_SMP
  38 #define INIT_PER_CPU_VAR(var)  init_per_cpu__##var
  39 #else
  40 #define INIT_PER_CPU_VAR(var)  per_cpu__##var
  41 #endif
  42
  43 #else /* ...!ASSEMBLY */
  44
  45 #include <linux/kernel.h>
  46 #include <linux/stringify.h>
  47
  48 #ifdef CONFIG_SMP
  49 #define __percpu_arg(x)         "%%"__stringify(__percpu_seg)":%P" #x
  50 #define __my_cpu_offset         percpu_read(this_cpu_off)
  51 #else
  52 #define __percpu_arg(x)         "%P" #x
  53 #endif
  54
  55 /*
  56  * Initialized pointers to per-cpu variables needed for the boot
  57  * processor need to use these macros to get the proper address
  58  * offset from __per_cpu_load on SMP.
  59  *
  60  * There also must be an entry in vmlinux_64.lds.S
  61  */
  62 #define DECLARE_INIT_PER_CPU(var) \
  63        extern typeof(per_cpu_var(var)) init_per_cpu_var(var)
  64
  65 #ifdef CONFIG_X86_64_SMP
  66 #define init_per_cpu_var(var)  init_per_cpu__##var
  67 #else
  68 #define init_per_cpu_var(var)  per_cpu_var(var)
  69 #endif
  70
  71 /* For arch-specific code, we can use direct single-insn ops (they
  72  * don't give an lvalue though). */
  73 extern void __bad_percpu_size(void);
  74
  75 #define percpu_to_op(op, var, val)                      \
  76 do {                                                    \
  77         typedef typeof(var) T__;                        \
  78         if (0) {                                        \
  79                 T__ tmp__;                              \
  80                 tmp__ = (val);                          \
  81         }                                               \
  82         switch (sizeof(var)) {                          \
  83         case 1:                                         \
  84                 asm(op "b %1,"__percpu_arg(0)           \
  85                     : "+m" (var)                        \
  86                     : "qi" ((T__)(val)));               \
  87                 break;                                  \
  88         case 2:                                         \
  89                 asm(op "w %1,"__percpu_arg(0)           \
  90                     : "+m" (var)                        \
  91                     : "ri" ((T__)(val)));               \
  92                 break;                                  \
  93         case 4:                                         \
  94                 asm(op "l %1,"__percpu_arg(0)           \
  95                     : "+m" (var)                        \
  96                     : "ri" ((T__)(val)));               \
  97                 break;                                  \
  98         case 8:                                         \
  99                 asm(op "q %1,"__percpu_arg(0)           \
 100                     : "+m" (var)                        \
 101                     : "re" ((T__)(val)));               \
 102                 break;                                  \
 103         default: __bad_percpu_size();                   \
 104         }                                               \
 105 } while (0)
 106
 107 #define percpu_from_op(op, var, constraint)             \
 108 ({                                                      \
 109         typeof(var) ret__;                              \
 110         switch (sizeof(var)) {                          \
 111         case 1:                                         \
 112                 asm(op "b "__percpu_arg(1)",%0"         \
 113                     : "=q" (ret__)                      \
 114                     : constraint);                      \
 115                 break;                                  \
 116         case 2:                                         \
 117                 asm(op "w "__percpu_arg(1)",%0"         \
 118                     : "=r" (ret__)                      \
 119                     : constraint);                      \
 120                 break;                                  \
 121         case 4:                                         \
 122                 asm(op "l "__percpu_arg(1)",%0"         \
 123                     : "=r" (ret__)                      \
 124                     : constraint);                      \
 125                 break;                                  \
 126         case 8:                                         \
 127                 asm(op "q "__percpu_arg(1)",%0"         \
 128                     : "=r" (ret__)                      \
 129                     : constraint);                      \
 130                 break;                                  \
 131         default: __bad_percpu_size();                   \
 132         }                                               \
 133         ret__;                                          \
 134 })
 135
 136 /*
 137  * percpu_read() makes gcc load the percpu variable every time it is
 138  * accessed while percpu_read_stable() allows the value to be cached.
 139  * percpu_read_stable() is more efficient and can be used if its value
 140  * is guaranteed to be valid across cpus.  The current users include
 141  * get_current() and get_thread_info() both of which are actually
 142  * per-thread variables implemented as per-cpu variables and thus
 143  * stable for the duration of the respective task.
 144  */
 145 #define percpu_read(var)        percpu_from_op("mov", per_cpu__##var,   \
 146                                                "m" (per_cpu__##var))
 147 #define percpu_read_stable(var) percpu_from_op("mov", per_cpu__##var,   \
 148                                                "p" (&per_cpu__##var))
 149 #define percpu_write(var, val)  percpu_to_op("mov", per_cpu__##var, val)
 150 #define percpu_add(var, val)    percpu_to_op("add", per_cpu__##var, val)
 151 #define percpu_sub(var, val)    percpu_to_op("sub", per_cpu__##var, val)
 152 #define percpu_and(var, val)    percpu_to_op("and", per_cpu__##var, val)
 153 #define percpu_or(var, val)     percpu_to_op("or", per_cpu__##var, val)
 154 #define percpu_xor(var, val)    percpu_to_op("xor", per_cpu__##var, val)
 155
 156 /* This is not atomic against other CPUs -- CPU preemption needs to be off */
 157 #define x86_test_and_clear_bit_percpu(bit, var)                         \
 158 ({                                                                      \
 159         int old__;                                                      \
 160         asm volatile("btr %2,"__percpu_arg(1)"\n\tsbbl %0,%0"           \
 161                      : "=r" (old__), "+m" (per_cpu__##var)              \
 162                      : "dIr" (bit));                                    \
 163         old__;                                                          \
 164 })
 165
 166 #include <asm-generic/percpu.h>
 167
 168 /* We can use this directly for local CPU (faster). */
 169 DECLARE_PER_CPU(unsigned long, this_cpu_off);
 170
 171 #endif /* !__ASSEMBLY__ */
 172
 173 #ifdef CONFIG_SMP
 174
 175 /*
 176  * Define the "EARLY_PER_CPU" macros.  These are used for some per_cpu
 177  * variables that are initialized and accessed before there are per_cpu
 178  * areas allocated.
 179  */
 180
 181 #define DEFINE_EARLY_PER_CPU(_type, _name, _initvalue)                  \
 182         DEFINE_PER_CPU(_type, _name) = _initvalue;                      \
 183         __typeof__(_type) _name##_early_map[NR_CPUS] __initdata =       \
 184                                 { [0 ... NR_CPUS-1] = _initvalue };     \
 185         __typeof__(_type) *_name##_early_ptr __refdata = _name##_early_map
 186
 187 #define EXPORT_EARLY_PER_CPU_SYMBOL(_name)                      \
 188         EXPORT_PER_CPU_SYMBOL(_name)
 189
 190 #define DECLARE_EARLY_PER_CPU(_type, _name)                     \
 191         DECLARE_PER_CPU(_type, _name);                          \
 192         extern __typeof__(_type) *_name##_early_ptr;            \
 193         extern __typeof__(_type)  _name##_early_map[]
 194
 195 #define early_per_cpu_ptr(_name) (_name##_early_ptr)
 196 #define early_per_cpu_map(_name, _idx) (_name##_early_map[_idx])
 197 #define early_per_cpu(_name, _cpu)                              \
 198         *(early_per_cpu_ptr(_name) ?                            \
 199                 &early_per_cpu_ptr(_name)[_cpu] :               \
 200                 &per_cpu(_name, _cpu))
 201
 202 #else   /* !CONFIG_SMP */
 203 #define DEFINE_EARLY_PER_CPU(_type, _name, _initvalue)          \
 204         DEFINE_PER_CPU(_type, _name) = _initvalue
 205
 206 #define EXPORT_EARLY_PER_CPU_SYMBOL(_name)                      \
 207         EXPORT_PER_CPU_SYMBOL(_name)
 208
 209 #define DECLARE_EARLY_PER_CPU(_type, _name)                     \
 210         DECLARE_PER_CPU(_type, _name)
 211
 212 #define early_per_cpu(_name, _cpu) per_cpu(_name, _cpu)
 213 #define early_per_cpu_ptr(_name) NULL
 214 /* no early_per_cpu_map() */
 215
 216 #endif  /* !CONFIG_SMP */
 217
 218 #endif /* _ASM_X86_PERCPU_H */