[PATCH] x86: increase interrupt vector range

Remove the limit of 256 interrupt vectors by changing the value stored in
orig_{e,r}ax to be the complemented 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>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Protasevich, Natalie" <Natalie.Protasevich@UNISYS.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index e6e4506..8713e02 100644 (file)
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -515,7 +515,7 @@ ENTRY(irq_entries_start)
  .if vector
        CFI_ADJUST_CFA_OFFSET -4
  .endif
-1:     pushl $vector-256
+1:     pushl $~(vector)
        CFI_ADJUST_CFA_OFFSET 4
        jmp common_interrupt
 .data
@@ -535,7 +535,7 @@ common_interrupt:
 #define BUILD_INTERRUPT(name, nr)      \
 ENTRY(name)                            \
        RING0_INT_FRAME;                \
-       pushl $nr-256;                  \
+       pushl $~(nr);                   \
        CFI_ADJUST_CFA_OFFSET 4;        \
        SAVE_ALL;                       \
        movl %esp,%eax;                 \

diff --git a/arch/i386/kernel/irq.c b/arch/i386/kernel/irq.c
index 061533e..586b15f 100644 (file)
--- a/arch/i386/kernel/irq.c
+++ b/arch/i386/kernel/irq.c
@@ -53,8 +53,8 @@ static union irq_ctx *softirq_ctx[NR_CPUS] __read_mostly;
  */
 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;

diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
index 7290e72..22cac44 100644 (file)
--- a/arch/x86_64/kernel/entry.S
+++ b/arch/x86_64/kernel/entry.S
@@ -588,7 +588,7 @@ END(common_interrupt)
  */            
        .macro apicinterrupt num,func
        INTR_FRAME
-       pushq $\num-256
+       pushq $~(\num)
        CFI_ADJUST_CFA_OFFSET 8
        interrupt \func
        jmp ret_from_intr

diff --git a/arch/x86_64/kernel/irq.c b/arch/x86_64/kernel/irq.c
index 59518d4..3be0a7e 100644 (file)
--- a/arch/x86_64/kernel/irq.c
+++ b/arch/x86_64/kernel/irq.c
@@ -115,8 +115,8 @@ 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();

diff --git a/arch/x86_64/kernel/smp.c b/arch/x86_64/kernel/smp.c
index acee4bc..5a1c0a3 100644 (file)
--- a/arch/x86_64/kernel/smp.c
+++ b/arch/x86_64/kernel/smp.c
@@ -135,10 +135,10 @@ asmlinkage void smp_invalidate_interrupt(struct pt_regs *regs)
 
        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))

diff --git a/include/asm-x86_64/hw_irq.h b/include/asm-x86_64/hw_irq.h
index 1b2ac55..9318774 100644 (file)
--- a/include/asm-x86_64/hw_irq.h
+++ b/include/asm-x86_64/hw_irq.h
@@ -124,7 +124,7 @@ 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)