arch/x86/kernel/smpcommon.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 #ifdef CONFIG_X86_32
   8 DEFINE_PER_CPU(unsigned long, this_cpu_off);
   9 EXPORT_PER_CPU_SYMBOL(this_cpu_off);
  10
  11 /* Initialize the CPU's GDT.  This is either the boot CPU doing itself
  12    (still using the master per-cpu area), or a CPU doing it for a
  13    secondary which will soon come up. */
  14 __cpuinit void init_gdt(int cpu)
  15 {
  16         struct desc_struct *gdt = get_cpu_gdt_table(cpu);
  17
  18         pack_descriptor(&gdt[GDT_ENTRY_PERCPU],
  19                         __per_cpu_offset[cpu], 0xFFFFF,
  20                         0x2 | DESCTYPE_S, 0x8);
  21
  22         gdt[GDT_ENTRY_PERCPU].s = 1;
  23
  24         per_cpu(this_cpu_off, cpu) = __per_cpu_offset[cpu];
  25         per_cpu(cpu_number, cpu) = cpu;
  26 }
  27 #endif
  28
  29 /**
  30  * smp_call_function(): Run a function on all other CPUs.
  31  * @func: The function to run. This must be fast and non-blocking.
  32  * @info: An arbitrary pointer to pass to the function.
  33  * @nonatomic: Unused.
  34  * @wait: If true, wait (atomically) until function has completed on other CPUs.
  35  *
  36  * Returns 0 on success, else a negative status code.
  37  *
  38  * If @wait is true, then returns once @func has returned; otherwise
  39  * it returns just before the target cpu calls @func.
  40  *
  41  * You must not call this function with disabled interrupts or from a
  42  * hardware interrupt handler or from a bottom half handler.
  43  */
  44 int smp_call_function(void (*func) (void *info), void *info, int nonatomic,
  45                       int wait)
  46 {
  47         return smp_call_function_mask(cpu_online_map, func, info, wait);
  48 }
  49 EXPORT_SYMBOL(smp_call_function);
  50
  51 /**
  52  * smp_call_function_single - Run a function on a specific CPU
  53  * @cpu: The target CPU.  Cannot be the calling CPU.
  54  * @func: The function to run. This must be fast and non-blocking.
  55  * @info: An arbitrary pointer to pass to the function.
  56  * @nonatomic: Unused.
  57  * @wait: If true, wait until function has completed on other CPUs.
  58  *
  59  * Returns 0 on success, else a negative status code.
  60  *
  61  * If @wait is true, then returns once @func has returned; otherwise
  62  * it returns just before the target cpu calls @func.
  63  */
  64 int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
  65                              int nonatomic, int wait)
  66 {
  67         /* prevent preemption and reschedule on another processor */
  68         int ret;
  69         int me = get_cpu();
  70         if (cpu == me) {
  71                 local_irq_disable();
  72                 func(info);
  73                 local_irq_enable();
  74                 put_cpu();
  75                 return 0;
  76         }
  77
  78         ret = smp_call_function_mask(cpumask_of_cpu(cpu), func, info, wait);
  79
  80         put_cpu();
  81         return ret;
  82 }
  83 EXPORT_SYMBOL(smp_call_function_single);