LXR linux/arch/x86/kernel/irq

   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
  23DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
  24EXPORT_PER_CPU_SYMBOL(irq_stat);
  25
  26DEFINE_PER_CPU(struct pt_regs *, irq_regs);
  27EXPORT_PER_CPU_SYMBOL(irq_regs);
  28
  29int sysctl_panic_on_stackoverflow;
  30
  31/*
  32 * Probabilistic stack overflow check:
  33 *
  34 * Only check the stack in process context, because everything else
  35 * runs on the big interrupt stacks. Checking reliably is too expensive,
  36 * so we just check from interrupts.
  37 */
  38static inline void stack_overflow_check(struct pt_regs *regs)
  39{
  40#ifdef CONFIG_DEBUG_STACKOVERFLOW
  41#define STACK_TOP_MARGIN        128
  42        struct orig_ist *oist;
  43        u64 irq_stack_top, irq_stack_bottom;
  44        u64 estack_top, estack_bottom;
  45        u64 curbase = (u64)task_stack_page(current);
  46
  47        if (user_mode_vm(regs))
  48                return;
  49
  50        if (regs->sp >= curbase + sizeof(struct thread_info) +
  51                                  sizeof(struct pt_regs) + STACK_TOP_MARGIN &&
  52            regs->sp <= curbase + THREAD_SIZE)
  53                return;
  54
  55        irq_stack_top = (u64)__get_cpu_var(irq_stack_union.irq_stack) +
  56                        STACK_TOP_MARGIN;
  57        irq_stack_bottom = (u64)__get_cpu_var(irq_stack_ptr);
  58        if (regs->sp >= irq_stack_top && regs->sp <= irq_stack_bottom)
  59                return;
  60
  61        oist = &__get_cpu_var(orig_ist);
  62        estack_top = (u64)oist->ist[0] - EXCEPTION_STKSZ + STACK_TOP_MARGIN;
  63        estack_bottom = (u64)oist->ist[N_EXCEPTION_STACKS - 1];
  64        if (regs->sp >= estack_top && regs->sp <= estack_bottom)
  65                return;
  66
  67        WARN_ONCE(1, "do_IRQ(): %s has overflown the kernel stack (cur:%Lx,sp:%lx,irq stk top-bottom:%Lx-%Lx,exception stk top-bottom:%Lx-%Lx)\n",
  68                current->comm, curbase, regs->sp,
  69                irq_stack_top, irq_stack_bottom,
  70                estack_top, estack_bottom);
  71
  72        if (sysctl_panic_on_stackoverflow)
  73                panic("low stack detected by irq handler - check messages\n");
  74#endif
  75}
  76
  77bool handle_irq(unsigned irq, struct pt_regs *regs)
  78{
  79        struct irq_desc *desc;
  80
  81        stack_overflow_check(regs);
  82
  83        desc = irq_to_desc(irq);
  84        if (unlikely(!desc))
  85                return false;
  86
  87        generic_handle_irq_desc(irq, desc);
  88        return true;
  89}
  90
  91
  92extern void call_softirq(void);
  93
  94asmlinkage void do_softirq(void)
  95{
  96        __u32 pending;
  97        unsigned long flags;
  98
  99        if (in_interrupt())
 100                return;
 101
 102        local_irq_save(flags);
 103        pending = local_softirq_pending();
 104        /* Switch to interrupt stack */
 105        if (pending) {
 106                call_softirq();
 107                WARN_ON_ONCE(softirq_count());
 108        }
 109        local_irq_restore(flags);
 110}
 111