include/asm-x86/percpu.h

   1 #ifndef _ASM_X86_PERCPU_H_
   2 #define _ASM_X86_PERCPU_H_
   3
   4 #ifdef CONFIG_X86_64
   5 #include <linux/compiler.h>
   6
   7 /* Same as asm-generic/percpu.h, except that we store the per cpu offset
   8    in the PDA. Longer term the PDA and every per cpu variable
   9    should be just put into a single section and referenced directly
  10    from %gs */
  11
  12 #ifdef CONFIG_SMP
  13 #include <asm/pda.h>
  14
  15 #define __per_cpu_offset(cpu) (cpu_pda(cpu)->data_offset)
  16 #define __my_cpu_offset read_pda(data_offset)
  17
  18 #define per_cpu_offset(x) (__per_cpu_offset(x))
  19
  20 #endif
  21 #include <asm-generic/percpu.h>
  22
  23 DECLARE_PER_CPU(struct x8664_pda, pda);
  24
  25 /*
  26  * These are supposed to be implemented as a single instruction which
  27  * operates on the per-cpu data base segment.  x86-64 doesn't have
  28  * that yet, so this is a fairly inefficient workaround for the
  29  * meantime.  The single instruction is atomic with respect to
  30  * preemption and interrupts, so we need to explicitly disable
  31  * interrupts here to achieve the same effect.  However, because it
  32  * can be used from within interrupt-disable/enable, we can't actually
  33  * disable interrupts; disabling preemption is enough.
  34  */
  35 #define x86_read_percpu(var)                                            \
  36         ({                                                              \
  37                 typeof(per_cpu_var(var)) __tmp;                         \
  38                 preempt_disable();                                      \
  39                 __tmp = __get_cpu_var(var);                             \
  40                 preempt_enable();                                       \
  41                 __tmp;                                                  \
  42         })
  43
  44 #define x86_write_percpu(var, val)                                      \
  45         do {                                                            \
  46                 preempt_disable();                                      \
  47                 __get_cpu_var(var) = (val);                             \
  48                 preempt_enable();                                       \
  49         } while(0)
  50
  51 #else /* CONFIG_X86_64 */
  52
  53 #ifdef __ASSEMBLY__
  54
  55 /*
  56  * PER_CPU finds an address of a per-cpu variable.
  57  *
  58  * Args:
  59  *    var - variable name
  60  *    reg - 32bit register
  61  *
  62  * The resulting address is stored in the "reg" argument.
  63  *
  64  * Example:
  65  *    PER_CPU(cpu_gdt_descr, %ebx)
  66  */
  67 #ifdef CONFIG_SMP
  68 #define PER_CPU(var, reg)                               \
  69         movl %fs:per_cpu__##this_cpu_off, reg;          \
  70         lea per_cpu__##var(reg), reg
  71 #define PER_CPU_VAR(var)        %fs:per_cpu__##var
  72 #else /* ! SMP */
  73 #define PER_CPU(var, reg)                       \
  74         movl $per_cpu__##var, reg
  75 #define PER_CPU_VAR(var)        per_cpu__##var
  76 #endif  /* SMP */
  77
  78 #else /* ...!ASSEMBLY */
  79
  80 /*
  81  * PER_CPU finds an address of a per-cpu variable.
  82  *
  83  * Args:
  84  *    var - variable name
  85  *    cpu - 32bit register containing the current CPU number
  86  *
  87  * The resulting address is stored in the "cpu" argument.
  88  *
  89  * Example:
  90  *    PER_CPU(cpu_gdt_descr, %ebx)
  91  */
  92 #ifdef CONFIG_SMP
  93
  94 #define __my_cpu_offset x86_read_percpu(this_cpu_off)
  95
  96 /* fs segment starts at (positive) offset == __per_cpu_offset[cpu] */
  97 #define __percpu_seg "%%fs:"
  98
  99 #else  /* !SMP */
 100
 101 #define __percpu_seg ""
 102
 103 #endif  /* SMP */
 104
 105 #include <asm-generic/percpu.h>
 106
 107 /* We can use this directly for local CPU (faster). */
 108 DECLARE_PER_CPU(unsigned long, this_cpu_off);
 109
 110 /* For arch-specific code, we can use direct single-insn ops (they
 111  * don't give an lvalue though). */
 112 extern void __bad_percpu_size(void);
 113
 114 #define percpu_to_op(op, var, val)                      \
 115 do {                                                    \
 116         typedef typeof(var) T__;                        \
 117         if (0) {                                        \
 118                 T__ tmp__;                              \
 119                 tmp__ = (val);                          \
 120         }                                               \
 121         switch (sizeof(var)) {                          \
 122         case 1:                                         \
 123                 asm(op "b %1,"__percpu_seg"%0"          \
 124                     : "+m" (var)                        \
 125                     : "ri" ((T__)val));                 \
 126                 break;                                  \
 127         case 2:                                         \
 128                 asm(op "w %1,"__percpu_seg"%0"          \
 129                     : "+m" (var)                        \
 130                     : "ri" ((T__)val));                 \
 131                 break;                                  \
 132         case 4:                                         \
 133                 asm(op "l %1,"__percpu_seg"%0"          \
 134                     : "+m" (var)                        \
 135                     : "ri" ((T__)val));                 \
 136                 break;                                  \
 137         default: __bad_percpu_size();                   \
 138         }                                               \
 139 } while (0)
 140
 141 #define percpu_from_op(op, var)                         \
 142 ({                                                      \
 143         typeof(var) ret__;                              \
 144         switch (sizeof(var)) {                          \
 145         case 1:                                         \
 146                 asm(op "b "__percpu_seg"%1,%0"          \
 147                     : "=r" (ret__)                      \
 148                     : "m" (var));                       \
 149                 break;                                  \
 150         case 2:                                         \
 151                 asm(op "w "__percpu_seg"%1,%0"          \
 152                     : "=r" (ret__)                      \
 153                     : "m" (var));                       \
 154                 break;                                  \
 155         case 4:                                         \
 156                 asm(op "l "__percpu_seg"%1,%0"          \
 157                     : "=r" (ret__)                      \
 158                     : "m" (var));                       \
 159                 break;                                  \
 160         default: __bad_percpu_size();                   \
 161         }                                               \
 162         ret__;                                          \
 163 })
 164
 165 #define x86_read_percpu(var) percpu_from_op("mov", per_cpu__##var)
 166 #define x86_write_percpu(var, val) percpu_to_op("mov", per_cpu__##var, val)
 167 #define x86_add_percpu(var, val) percpu_to_op("add", per_cpu__##var, val)
 168 #define x86_sub_percpu(var, val) percpu_to_op("sub", per_cpu__##var, val)
 169 #define x86_or_percpu(var, val) percpu_to_op("or", per_cpu__##var, val)
 170 #endif /* !__ASSEMBLY__ */
 171 #endif /* !CONFIG_X86_64 */
 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 = _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_ */