linux/arch/mips/kernel/irq.c

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Code to handle x86 style IRQs plus some generic interrupt stuff.
 *
 * Copyright (C) 1992 Linus Torvalds
 * Copyright (C) 1994 - 2000 Ralf Baechle
 */
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/proc_fs.h>
#include <linux/mm.h>
#include <linux/random.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/kallsyms.h>
#include <linux/kgdb.h>
#include <linux/ftrace.h>

#include <linux/atomic.h>
#include <linux/uaccess.h>

void *irq_stack[NR_CPUS];

/*
 * 'what should we do if we get a hw irq event on an illegal vector'.
 * each architecture has to answer this themselves.
 */
void ack_bad_irq(unsigned int irq)
{
	printk("unexpected IRQ # %d\n", irq);
}

atomic_t irq_err_count;

int arch_show_interrupts(struct seq_file *p, int prec)
{
	seq_printf(p, "%*s: %10u\n", prec, "ERR", atomic_read(&irq_err_count));
	return 0;
}

asmlinkage void spurious_interrupt(void)
{
	atomic_inc(&irq_err_count);
}

void __init init_IRQ(void)
{
	int i;
	unsigned int order = get_order(IRQ_STACK_SIZE);

	for (i = 0; i < NR_IRQS; i++)
		irq_set_noprobe(i);

	if (cpu_has_veic)
		clear_c0_status(ST0_IM);

	arch_init_irq();

	for_each_possible_cpu(i) {
		void *s = (void *)__get_free_pages(GFP_KERNEL, order);

		irq_stack[i] = s;
		pr_debug("CPU%d IRQ stack at 0x%p - 0x%p\n", i,
			irq_stack[i], irq_stack[i] + IRQ_STACK_SIZE);
	}
}

#ifdef CONFIG_DEBUG_STACKOVERFLOW
static inline void check_stack_overflow(void)
{
	unsigned long sp;

	__asm__ __volatile__("move %0, $sp" : "=r" (sp));
	sp &= THREAD_MASK;

	/*
	 * Check for stack overflow: is there less than STACK_WARN free?
	 * STACK_WARN is defined as 1/8 of THREAD_SIZE by default.
	 */
	if (unlikely(sp < (sizeof(struct thread_info) + STACK_WARN))) {
		printk("do_IRQ: stack overflow: %ld\n",
		       sp - sizeof(struct thread_info));
		dump_stack();
	}
}
#else
static inline void check_stack_overflow(void) {}
#endif


/*
 * do_IRQ handles all normal device IRQ's (the special
 * SMP cross-CPU interrupts have their own specific
 * handlers).
 */
void __irq_entry do_IRQ(unsigned int irq)
{
	irq_enter();
	check_stack_overflow();
	generic_handle_irq(irq);
	irq_exit();
}