[RFC PATCH 23/35] Increase x86 interrupt vector range

Chris Wright
2006-05-09T08:49:52Z

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Remove the limit of 256 interrupt vectors by changing the value
stored in orig_{e,r}ax to be the negated interrupt vector.
The orig_{e,r}ax needs to be < 0 to allow the signal code to
distinguish between return from interrupt and return from syscall.
With this change applied, NR_IRQS can be > 256.

Xen extends the IRQ numbering space to include room for dynamically
allocated virtual interrupts (in the range 256-511), which requires a
more permissive interface to do_IRQ.

Signed-off-by: Ian Pratt <ian.pratt@xensource.com>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
arch/i386/kernel/entry.S | 4 ++--
arch/i386/kernel/irq.c | 4 ++--
arch/x86_64/kernel/entry.S | 2 +-
arch/x86_64/kernel/irq.c | 4 ++--
arch/x86_64/kernel/smp.c | 4 ++--
include/asm-x86_64/hw_irq.h | 2 +-
6 files changed, 10 insertions(+), 10 deletions(-)

--- linus-2.6.orig/arch/i386/kernel/entry.S
+++ linus-2.6/arch/i386/kernel/entry.S
@@ -464,7 +464,7 @@ vector=0
ENTRY(irq_entries_start)
.rept NR_IRQS
ALIGN
-1: pushl $vector-256
+1: pushl $~(vector)
jmp common_interrupt
.data
.long 1b
@@ -481,7 +481,7 @@ common_interrupt:

#define BUILD_INTERRUPT(name, nr) \
ENTRY(name) \
- pushl $nr-256; \
+ pushl $~(nr); \
SAVE_ALL \
movl %esp,%eax; \
call smp_/**/name; \
--- linus-2.6.orig/arch/i386/kernel/irq.c
+++ linus-2.6/arch/i386/kernel/irq.c
@@ -53,8 +53,8 @@ static union irq_ctx *softirq_ctx[NR_CPU
*/
fastcall unsigned int do_IRQ(struct pt_regs *regs)
{
- /* high bits used in ret_from_ code */
- int irq = regs->orig_eax & 0xff;
+ /* high bit used in ret_from_ code */
+ int irq = ~regs->orig_eax;
#ifdef CONFIG_4KSTACKS
union irq_ctx *curctx, *irqctx;
u32 *isp;
--- linus-2.6.orig/arch/x86_64/kernel/entry.S
+++ linus-2.6/arch/x86_64/kernel/entry.S
@@ -601,7 +601,7 @@ retint_kernel:
*/
.macro apicinterrupt num,func
INTR_FRAME
- pushq $\num-256
+ pushq $~(\num)
CFI_ADJUST_CFA_OFFSET 8
interrupt \func
jmp ret_from_intr
--- linus-2.6.orig/arch/x86_64/kernel/irq.c
+++ linus-2.6/arch/x86_64/kernel/irq.c
@@ -91,8 +91,8 @@ skip:
*/
asmlinkage unsigned int do_IRQ(struct pt_regs *regs)
{
- /* high bits used in ret_from_ code */
- unsigned irq = regs->orig_rax & 0xff;
+ /* high bit used in ret_from_ code */
+ unsigned irq = ~regs->orig_rax;

exit_idle();
irq_enter();
--- linus-2.6.orig/arch/x86_64/kernel/smp.c
+++ linus-2.6/arch/x86_64/kernel/smp.c
@@ -135,10 +135,10 @@ asmlinkage void smp_invalidate_interrupt

cpu = smp_processor_id();
/*
- * orig_rax contains the interrupt vector - 256.
+ * orig_rax contains the negated interrupt vector.
* Use that to determine where the sender put the data.
*/
- sender = regs->orig_rax + 256 - INVALIDATE_TLB_VECTOR_START;
+ sender = ~regs->orig_rax - INVALIDATE_TLB_VECTOR_START;
f = &per_cpu(flush_state, sender);

if (!cpu_isset(cpu, f->flush_cpumask))
--- linus-2.6.orig/include/asm-x86_64/hw_irq.h
+++ linus-2.6/include/asm-x86_64/hw_irq.h
@@ -127,7 +127,7 @@ asmlinkage void IRQ_NAME(nr); \
__asm__( \
"\n.p2align\n" \
"IRQ" #nr "_interrupt:\n\t" \
- "push $" #nr "-256 ; " \
+ "push $~(" #nr ") ; " \
"jmp common_interrupt");

#if defined(CONFIG_X86_IO_APIC)

--