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(&gdt[GDT_ENTRY_PERCPU],
  18                         __per_cpu_offset[cpu], 0xFFFFF,
  19                         0x2 | DESCTYPE_S, 0x8);
  20
  21         gdt[GDT_ENTRY_PERCPU].s = 1;
  22
  23         per_cpu(this_cpu_off, cpu) = __per_cpu_offset[cpu];
  24         per_cpu(cpu_number, cpu) = cpu;
  25 }
  26
  27
  28 /**
  29  * smp_call_function(): Run a function on all other CPUs.
  30  * @func: The function to run. This must be fast and non-blocking.
  31  * @info: An arbitrary pointer to pass to the function.
  32  * @nonatomic: Unused.
  33  * @wait: If true, wait (atomically) until function has completed on other CPUs.
  34  *
  35  * Returns 0 on success, else a negative status code.
  36  *
  37  * If @wait is true, then returns once @func has returned; otherwise
  38  * it returns just before the target cpu calls @func.
  39  *
  40  * You must not call this function with disabled interrupts or from a
  41  * hardware interrupt handler or from a bottom half handler.
  42  */
  43 int smp_call_function(void (*func) (void *info), void *info, int nonatomic,
  44                       int wait)
  45 {
  46         return smp_call_function_mask(cpu_online_map, func, info, wait);
  47 }
  48 EXPORT_SYMBOL(smp_call_function);
  49
  50 /**
  51  * smp_call_function_single - Run a function on a specific CPU
  52  * @cpu: The target CPU.  Cannot be the calling CPU.
  53  * @func: The function to run. This must be fast and non-blocking.
  54  * @info: An arbitrary pointer to pass to the function.
  55  * @nonatomic: Unused.
  56  * @wait: If true, wait until function has completed on other CPUs.
  57  *
  58  * Returns 0 on success, else a negative status code.
  59  *
  60  * If @wait is true, then returns once @func has returned; otherwise
  61  * it returns just before the target cpu calls @func.
  62  */
  63 int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
  64                              int nonatomic, int wait)
  65 {
  66         /* prevent preemption and reschedule on another processor */
  67         int ret;
  68         int me = get_cpu();
  69         if (cpu == me) {
  70                 local_irq_disable();
  71                 func(info);
  72                 local_irq_enable();
  73                 put_cpu();
  74                 return 0;
  75         }
  76
  77         ret = smp_call_function_mask(cpumask_of_cpu(cpu), func, info, wait);
  78
  79         put_cpu();
  80         return ret;
  81 }
  82 EXPORT_SYMBOL(smp_call_function_single);