x86: unify do_IRQ()

With the differences in interrupt handling hoisted into handle_irq(),
do_IRQ is more or less identical between 32 and 64 bit, so unify it.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/irq.c

@@ -6,10 +6,12 @@
 #include <linux/kernel_stat.h>
 #include <linux/seq_file.h>
 #include <linux/smp.h>
+#include <linux/ftrace.h>
 
 #include <asm/apic.h>
 #include <asm/io_apic.h>
 #include <asm/irq.h>
+#include <asm/idle.h>
 
 atomic_t irq_err_count;
 
@@ -188,4 +190,40 @@ u64 arch_irq_stat(void)
 	return sum;
 }
 
+
+/*
+ * do_IRQ handles all normal device IRQ's (the special
+ * SMP cross-CPU interrupts have their own specific
+ * handlers).
+ */
+unsigned int __irq_entry do_IRQ(struct pt_regs *regs)
+{
+	struct pt_regs *old_regs = set_irq_regs(regs);
+
+	/* high bit used in ret_from_ code  */
+	unsigned vector = ~regs->orig_ax;
+	unsigned irq;
+
+	exit_idle();
+	irq_enter();
+
+	irq = __get_cpu_var(vector_irq)[vector];
+
+	if (!handle_irq(irq, regs)) {
+#ifdef CONFIG_X86_64
+		if (!disable_apic)
+			ack_APIC_irq();
+#endif
+
+		if (printk_ratelimit())
+			printk(KERN_EMERG "%s: %d.%d No irq handler for vector (irq %d)\n",
+			       __func__, smp_processor_id(), vector, irq);
+	}
+
+	irq_exit();
+
+	set_irq_regs(old_regs);
+	return 1;
+}
+
 EXPORT_SYMBOL_GPL(vector_used_by_percpu_irq);