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(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)this_cpu_ptr(irq_stack_union.irq_stack) +
56			STACK_TOP_MARGIN;
57	irq_stack_bottom = (u64)__this_cpu_read(irq_stack_ptr);
58	if (regs->sp >= irq_stack_top && regs->sp <= irq_stack_bottom)
59		return;
60
61	oist = this_cpu_ptr(&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