x86: add handle_irq() to allow interrupt injection

Xen uses a different interrupt path, so introduce handle_irq() to allow interrupts to be inserted into the normal interrupt path. This is handled slightly differently on 32 and 64-bit.

---

arch/x86/include/asm/irq.h |    1 +
arch/x86/kernel/irq_32.c   |   34 +++++++++++++++++++++-------------
arch/x86/kernel/irq_64.c   |   23 ++++++++++++++++-------
3 files changed, 38 insertions(+), 20 deletions(-)

===================================================================

@@ -39,6 +39,7 @@

extern unsigned int do_IRQ(struct pt_regs *regs); extern void init_IRQ(void);
extern void native_init_IRQ(void);
+extern bool handle_irq(unsigned irq, struct pt_regs *regs);

/* Interrupt vector management */
extern DECLARE_BITMAP(used_vectors, NR_VECTORS);
===================================================================

@@ -191,6 +191,26 @@

execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq) { return 0; } #endif

+bool handle_irq(unsigned irq, struct pt_regs *regs) +{
+ struct irq_desc *desc;
+ int overflow;
+
+ overflow = check_stack_overflow();
+
+ desc = irq_to_desc(irq);
+ if (unlikely(!desc))
+ return false;
+
+ if (!execute_on_irq_stack(overflow, desc, irq)) {
+ if (unlikely(overflow))
+ print_stack_overflow();
+ desc->handle_irq(irq, desc);
+ }
+
+ return true;
+}
+
/*
* do_IRQ handles all normal device IRQ's (the special
* SMP cross-CPU interrupts have their own specific
@@ -200,31 +220,19 @@

{
	struct pt_regs *old_regs;
	/* high bit used in ret_from_ code */
-	int overflow;
	unsigned vector = ~regs->orig_ax;
-	struct irq_desc *desc;
	unsigned irq;

-

	old_regs = set_irq_regs(regs);
	irq_enter();
	irq = __get_cpu_var(vector_irq)[vector];

- overflow = check_stack_overflow();
-
- desc = irq_to_desc(irq);
- if (unlikely(!desc)) {

+	if (!handle_irq(irq, regs)) {
		printk(KERN_EMERG "%s: cannot handle IRQ %d vector %#x cpu %d\n",
					__func__, irq, vector, smp_processor_id());
		BUG();
	}

- if (!execute_on_irq_stack(overflow, desc, irq)) {
- if (unlikely(overflow))
- print_stack_overflow();
- desc->handle_irq(irq, desc);
- }
-

	irq_exit();
	set_irq_regs(old_regs);
	return 1;

===================================================================

@@ -40,6 +40,20 @@

#endif
}

+bool handle_irq(unsigned irq, struct pt_regs *regs) +{
+ struct irq_desc *desc;
+
+ stack_overflow_check(regs);
+
+ desc = irq_to_desc(irq);
+ if (unlikely(!desc))
+ return false;
+
+ generic_handle_irq_desc(irq, desc);
+ return true;
+}
+
/*
* do_IRQ handles all normal device IRQ's (the special
* SMP cross-CPU interrupts have their own specific
@@ -48,7 +62,6 @@
asmlinkage unsigned int do_IRQ(struct pt_regs *regs)

{
	struct pt_regs *old_regs = set_irq_regs(regs);

- struct irq_desc *desc;

	/* high bit used in ret_from_ code  */
	unsigned vector = ~regs->orig_ax;

@@ -56,14 +69,10 @@

	exit_idle();
	irq_enter();
+
	irq = __get_cpu_var(vector_irq)[vector];

- stack_overflow_check(regs);
-
- desc = irq_to_desc(irq);
- if (likely(desc))
- generic_handle_irq_desc(irq, desc);
- else {

+	if (!handle_irq(irq, regs)) {
		if (!disable_apic)
			ack_APIC_irq();

I didn't really add more logic - I just hoisted some existing code into a new function.

It does make do_IRQ() itself trivial to unify now. But the rest looks non-trivial: fixup_irqs() is quite different, as is the interrupt stack stuff.

Hm, what does asmlinkage do on x86-64?

J

Subject: 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.

---

arch/x86/include/asm/irq.h |    1 -
arch/x86/kernel/irq.c      |   41 +++++++++++++++++++++++++++++++++++++++++
arch/x86/kernel/irq_32.c   |   27 ---------------------------
arch/x86/kernel/irq_64.c   |   33 ---------------------------------
4 files changed, 41 insertions(+), 61 deletions(-)

===================================================================

@@ -36,7 +36,6 @@

extern void fixup_irqs(cpumask_t map);
#endif

-extern unsigned int do_IRQ(struct pt_regs *regs); extern void init_IRQ(void);
extern void native_init_IRQ(void);
extern bool handle_irq(unsigned irq, struct pt_regs *regs);
===================================================================

@@ -5,10 +5,12 @@

#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/seq_file.h>
+#include <linux/ftrace.h>

#include <asm/apic.h>
#include <asm/io_apic.h>
#include <asm/smp.h>
+#include <asm/idle.h>

atomic_t irq_err_count;

@@ -195,3 +197,42 @@

#endif
	return sum;
}

+
+
+/*
+ * do_IRQ handles all normal device IRQ's (the special
+ * SMP cross-CPU interrupts have their own specific
+ * handlers).
+ */
+#ifdef CONFIG_X86_64
+asmlinkage
+#endif
+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;
+}
===================================================================

@@ -211,33 +211,6 @@

	return true;
}

-/*
- * do_IRQ handles all normal device IRQ's (the special
- * SMP cross-CPU interrupts have their own specific
- * handlers).
- */
-unsigned int do_IRQ(struct pt_regs *regs)
-{
- struct pt_regs *old_regs;
- /* high bit used in ret_from_ code */
- unsigned vector = ~regs->orig_ax;
- unsigned irq;
-
- old_regs = set_irq_regs(regs);
- irq_enter();
- irq = __get_cpu_var(vector_irq)[vector];
-
- if (!handle_irq(irq, regs)) {
- printk(KERN_EMERG "%s: cannot handle IRQ %d vector %#x cpu %d\n",
- __func__, irq, vector, smp_processor_id());
- BUG();
- }
-
- irq_exit();
- set_irq_regs(old_regs);
- return 1;
-}
-
#ifdef CONFIG_HOTPLUG_CPU
#include <mach_apic.h>

===================================================================

@@ -55,39 +55,6 @@

	return true;
}

-/*
- * do_IRQ handles all normal device IRQ's (the special
- * SMP cross-CPU interrupts have their own specific
- * handlers).
- */
-asmlinkage 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)) {
- if (!disable_apic)
- ack_APIC_irq();
-
- if (printk_ratelimit())
- printk(KERN_EMERG "%s: %d.%d No irq handler for vector\n",
- __func__, smp_processor_id(), vector);
- }
-
- irq_exit();
-
- set_irq_regs(old_regs);
- return 1;
-}
-
#ifdef CONFIG_HOTPLUG_CPU
void fixup_irqs(cpumask_t map)
{

On Thu, Dec 18, 2008 at 2:06 AM, Jeremy Fitzhardinge <[email protected]> wrote:
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