Linux Kernel  3.7.1
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irq_64.c
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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 
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  */
38 static 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 
73  panic("low stack detected by irq handler - check messages\n");
74 #endif
75 }
76 
77 bool 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 
92 extern void call_softirq(void);
93 
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();
108  }
109  local_irq_restore(flags);
110 }