arch/x86/kernel/smpcommon_32.c

   1 /*
   2  * SMP stuff which is common to all sub-architectures.
   3  */
   4 #include <linux/module.h>
   5 #include <asm/smp.h>
   6
   7 DEFINE_PER_CPU(unsigned long, this_cpu_off);
   8 EXPORT_PER_CPU_SYMBOL(this_cpu_off);
   9
  10 /* Initialize the CPU's GDT.  This is either the boot CPU doing itself
  11    (still using the master per-cpu area), or a CPU doing it for a
  12    secondary which will soon come up. */
  13 __cpuinit void init_gdt(int cpu)
  14 {
  15         struct desc_struct *gdt = get_cpu_gdt_table(cpu);
  16
  17         pack_descriptor((u32 *)&gdt[GDT_ENTRY_PERCPU].a,
  18                         (u32 *)&gdt[GDT_ENTRY_PERCPU].b,
  19                         __per_cpu_offset[cpu], 0xFFFFF,
  20                         0x80 | DESCTYPE_S | 0x2, 0x8);
  21
  22         per_cpu(this_cpu_off, cpu) = __per_cpu_offset[cpu];
  23         per_cpu(cpu_number, cpu) = cpu;
  24 }
  25
  26
  27 /**
  28  * smp_call_function(): Run a function on all other CPUs.
  29  * @func: The function to run. This must be fast and non-blocking.
  30  * @info: An arbitrary pointer to pass to the function.
  31  * @nonatomic: Unused.
  32  * @wait: If true, wait (atomically) until function has completed on other CPUs.
  33  *
  34  * Returns 0 on success, else a negative status code.
  35  *
  36  * If @wait is true, then returns once @func has returned; otherwise
  37  * it returns just before the target cpu calls @func.
  38  *
  39  * You must not call this function with disabled interrupts or from a
  40  * hardware interrupt handler or from a bottom half handler.
  41  */
  42 int smp_call_function(void (*func) (void *info), void *info, int nonatomic,
  43                       int wait)
  44 {
  45         return smp_call_function_mask(cpu_online_map, func, info, wait);
  46 }
  47 EXPORT_SYMBOL(smp_call_function);
  48
  49 /**
  50  * smp_call_function_single - Run a function on a specific CPU
  51  * @cpu: The target CPU.  Cannot be the calling CPU.
  52  * @func: The function to run. This must be fast and non-blocking.
  53  * @info: An arbitrary pointer to pass to the function.
  54  * @nonatomic: Unused.
  55  * @wait: If true, wait until function has completed on other CPUs.
  56  *
  57  * Returns 0 on success, else a negative status code.
  58  *
  59  * If @wait is true, then returns once @func has returned; otherwise
  60  * it returns just before the target cpu calls @func.
  61  */
  62 int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
  63                              int nonatomic, int wait)
  64 {
  65         /* prevent preemption and reschedule on another processor */
  66         int ret;
  67         int me = get_cpu();
  68         if (cpu == me) {
  69                 local_irq_disable();
  70                 func(info);
  71                 local_irq_enable();
  72                 put_cpu();
  73                 return 0;
  74         }
  75
  76         ret = smp_call_function_mask(cpumask_of_cpu(cpu), func, info, wait);
  77
  78         put_cpu();
  79         return ret;
  80 }
  81 EXPORT_SYMBOL(smp_call_function_single);