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 #else /* ...!ASSEMBLY */
  38
  39 #include <linux/stringify.h>
  40
  41 #ifdef CONFIG_SMP
  42 #define __percpu_seg_str        "%%"__stringify(__percpu_seg)":"
  43 #define __my_cpu_offset         x86_read_percpu(this_cpu_off)
  44 #else
  45 #define __percpu_seg_str
  46 #endif
  47
  48 #include <asm-generic/percpu.h>
  49
  50 /* We can use this directly for local CPU (faster). */
  51 DECLARE_PER_CPU(unsigned long, this_cpu_off);
  52
  53 /* For arch-specific code, we can use direct single-insn ops (they
  54  * don't give an lvalue though). */
  55 extern void __bad_percpu_size(void);
  56
  57 #define percpu_to_op(op, var, val)                      \
  58 do {                                                    \
  59         typedef typeof(var) T__;                        \
  60         if (0) {                                        \
  61                 T__ tmp__;                              \
  62                 tmp__ = (val);                          \
  63         }                                               \
  64         switch (sizeof(var)) {                          \
  65         case 1:                                         \
  66                 asm(op "b %1,"__percpu_seg_str"%0"      \
  67                     : "+m" (var)                        \
  68                     : "ri" ((T__)val));                 \
  69                 break;                                  \
  70         case 2:                                         \
  71                 asm(op "w %1,"__percpu_seg_str"%0"      \
  72                     : "+m" (var)                        \
  73                     : "ri" ((T__)val));                 \
  74                 break;                                  \
  75         case 4:                                         \
  76                 asm(op "l %1,"__percpu_seg_str"%0"      \
  77                     : "+m" (var)                        \
  78                     : "ri" ((T__)val));                 \
  79                 break;                                  \
  80         case 8:                                         \
  81                 asm(op "q %1,"__percpu_seg_str"%0"      \
  82                     : "+m" (var)                        \
  83                     : "r" ((T__)val));                  \
  84                 break;                                  \
  85         default: __bad_percpu_size();                   \
  86         }                                               \
  87 } while (0)
  88
  89 #define percpu_from_op(op, var)                         \
  90 ({                                                      \
  91         typeof(var) ret__;                              \
  92         switch (sizeof(var)) {                          \
  93         case 1:                                         \
  94                 asm(op "b "__percpu_seg_str"%1,%0"      \
  95                     : "=r" (ret__)                      \
  96                     : "m" (var));                       \
  97                 break;                                  \
  98         case 2:                                         \
  99                 asm(op "w "__percpu_seg_str"%1,%0"      \
 100                     : "=r" (ret__)                      \
 101                     : "m" (var));                       \
 102                 break;                                  \
 103         case 4:                                         \
 104                 asm(op "l "__percpu_seg_str"%1,%0"      \
 105                     : "=r" (ret__)                      \
 106                     : "m" (var));                       \
 107                 break;                                  \
 108         case 8:                                         \
 109                 asm(op "q "__percpu_seg_str"%1,%0"      \
 110                     : "=r" (ret__)                      \
 111                     : "m" (var));                       \
 112                 break;                                  \
 113         default: __bad_percpu_size();                   \
 114         }                                               \
 115         ret__;                                          \
 116 })
 117
 118 #define x86_read_percpu(var) percpu_from_op("mov", per_cpu__##var)
 119 #define x86_write_percpu(var, val) percpu_to_op("mov", per_cpu__##var, val)
 120 #define x86_add_percpu(var, val) percpu_to_op("add", per_cpu__##var, val)
 121 #define x86_sub_percpu(var, val) percpu_to_op("sub", per_cpu__##var, val)
 122 #define x86_or_percpu(var, val) percpu_to_op("or", per_cpu__##var, val)
 123
 124 /* This is not atomic against other CPUs -- CPU preemption needs to be off */
 125 #define x86_test_and_clear_bit_percpu(bit, var)                         \
 126 ({                                                                      \
 127         int old__;                                                      \
 128         asm volatile("btr %1,"__percpu_seg_str"%c2\n\tsbbl %0,%0"       \
 129                      : "=r" (old__)                                     \
 130                      : "dIr" (bit), "i" (&per_cpu__##var) : "memory");  \
 131         old__;                                                          \
 132 })
 133
 134 #ifdef CONFIG_X86_64
 135 extern void load_pda_offset(int cpu);
 136 #else
 137 static inline void load_pda_offset(int cpu) { }
 138 #endif
 139
 140 #endif /* !__ASSEMBLY__ */
 141
 142 #ifdef CONFIG_SMP
 143
 144 /*
 145  * Define the "EARLY_PER_CPU" macros.  These are used for some per_cpu
 146  * variables that are initialized and accessed before there are per_cpu
 147  * areas allocated.
 148  */
 149
 150 #define DEFINE_EARLY_PER_CPU(_type, _name, _initvalue)                  \
 151         DEFINE_PER_CPU(_type, _name) = _initvalue;                      \
 152         __typeof__(_type) _name##_early_map[NR_CPUS] __initdata =       \
 153                                 { [0 ... NR_CPUS-1] = _initvalue };     \
 154         __typeof__(_type) *_name##_early_ptr __refdata = _name##_early_map
 155
 156 #define EXPORT_EARLY_PER_CPU_SYMBOL(_name)                      \
 157         EXPORT_PER_CPU_SYMBOL(_name)
 158
 159 #define DECLARE_EARLY_PER_CPU(_type, _name)                     \
 160         DECLARE_PER_CPU(_type, _name);                          \
 161         extern __typeof__(_type) *_name##_early_ptr;            \
 162         extern __typeof__(_type)  _name##_early_map[]
 163
 164 #define early_per_cpu_ptr(_name) (_name##_early_ptr)
 165 #define early_per_cpu_map(_name, _idx) (_name##_early_map[_idx])
 166 #define early_per_cpu(_name, _cpu)                              \
 167         *(early_per_cpu_ptr(_name) ?                            \
 168                 &early_per_cpu_ptr(_name)[_cpu] :               \
 169                 &per_cpu(_name, _cpu))
 170
 171 #else   /* !CONFIG_SMP */
 172 #define DEFINE_EARLY_PER_CPU(_type, _name, _initvalue)          \
 173         DEFINE_PER_CPU(_type, _name) = _initvalue
 174
 175 #define EXPORT_EARLY_PER_CPU_SYMBOL(_name)                      \
 176         EXPORT_PER_CPU_SYMBOL(_name)
 177
 178 #define DECLARE_EARLY_PER_CPU(_type, _name)                     \
 179         DECLARE_PER_CPU(_type, _name)
 180
 181 #define early_per_cpu(_name, _cpu) per_cpu(_name, _cpu)
 182 #define early_per_cpu_ptr(_name) NULL
 183 /* no early_per_cpu_map() */
 184
 185 #endif  /* !CONFIG_SMP */
 186
 187 #endif /* _ASM_X86_PERCPU_H */