release/src-rt-6.x.4708/linux/linux-2.6.36/arch/x86/kernel/irq_64.c

   1 /*
   2  *      Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
   3  *
   4  * This file contains the lowest level x86_64-specific interrupt
   5  * entry and irq statistics code. All the remaining irq logic is
   6  * done by the generic kernel/irq/ code and in the
   7  * x86_64-specific irq controller code. (e.g. i8259.c and
   8  * io_apic.c.)
   9  */
  10
  11 #include <linux/kernel_stat.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/seq_file.h>
  14 #include <linux/module.h>
  15 #include <linux/delay.h>
  16 #include <linux/ftrace.h>
  17 #include <linux/uaccess.h>
  18 #include <linux/smp.h>
  19 #include <asm/io_apic.h>
  20 #include <asm/idle.h>
  21 #include <asm/apic.h>
  22
  23 DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
  24 EXPORT_PER_CPU_SYMBOL(irq_stat);
  25
  26 DEFINE_PER_CPU(struct pt_regs *, irq_regs);
  27 EXPORT_PER_CPU_SYMBOL(irq_regs);
  28
  29 /*
  30  * Probabilistic stack overflow check:
  31  *
  32  * Only check the stack in process context, because everything else
  33  * runs on the big interrupt stacks. Checking reliably is too expensive,
  34  * so we just check from interrupts.
  35  */
  36 static inline void stack_overflow_check(struct pt_regs *regs)
  37 {
  38 #ifdef CONFIG_DEBUG_STACKOVERFLOW
  39         u64 curbase = (u64)task_stack_page(current);
  40
  41         WARN_ONCE(regs->sp >= curbase &&
  42                   regs->sp <= curbase + THREAD_SIZE &&
  43                   regs->sp <  curbase + sizeof(struct thread_info) +
  44                                         sizeof(struct pt_regs) + 128,
  45
  46                   "do_IRQ: %s near stack overflow (cur:%Lx,sp:%lx)\n",
  47                         current->comm, curbase, regs->sp);
  48 #endif
  49 }
  50
  51 bool handle_irq(unsigned irq, struct pt_regs *regs)
  52 {
  53         struct irq_desc *desc;
  54
  55         stack_overflow_check(regs);
  56
  57         desc = irq_to_desc(irq);
  58         if (unlikely(!desc))
  59                 return false;
  60
  61         generic_handle_irq_desc(irq, desc);
  62         return true;
  63 }
  64
  65
  66 extern void call_softirq(void);
  67
  68 asmlinkage void do_softirq(void)
  69 {
  70         __u32 pending;
  71         unsigned long flags;
  72
  73         if (in_interrupt())
  74                 return;
  75
  76         local_irq_save(flags);
  77         pending = local_softirq_pending();
  78         /* Switch to interrupt stack */
  79         if (pending) {
  80                 call_softirq();
  81                 WARN_ON_ONCE(softirq_count());
  82         }
  83         local_irq_restore(flags);
  84 }