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Subject[PATCH 10 of 38] x86: add handle_irq() to allow interrupt injection
Date
From
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.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
arch/x86/include/asm/irq.h | 1 +
arch/x86/kernel/irq_32.c | 34 +++++++++++++++++++++-------------
arch/x86/kernel/irq_64.c | 27 ++++++++++++++++++---------
3 files changed, 40 insertions(+), 22 deletions(-)
diff --git a/arch/x86/include/asm/irq.h b/arch/x86/include/asm/irq.h
--- a/arch/x86/include/asm/irq.h
+++ b/arch/x86/include/asm/irq.h
@@ -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);
diff --git a/arch/x86/kernel/irq_32.c b/arch/x86/kernel/irq_32.c
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
@@ -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;
diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -42,6 +42,22 @@
}
#endif

+bool handle_irq(unsigned irq, struct pt_regs *regs)
+{
+ struct irq_desc *desc;
+
+#ifdef CONFIG_DEBUG_STACKOVERFLOW
+ stack_overflow_check(regs);
+#endif
+
+ 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
@@ -50,7 +66,6 @@
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;
@@ -58,16 +73,10 @@

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

-#ifdef CONFIG_DEBUG_STACKOVERFLOW
- stack_overflow_check(regs);
-#endif
-
- 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();




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