x86: irq_32 move 4kstacks code to one place

Move the 4KSTACKS related code to one place. This allows to un#ifdef
do_IRQ() and share the executed on stack for the stack overflow printk
and the softirq call.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/irq_32.c

@@ -83,26 +83,28 @@ union irq_ctx {
 static union irq_ctx *hardirq_ctx[NR_CPUS] __read_mostly;
 static union irq_ctx *softirq_ctx[NR_CPUS] __read_mostly;
 
-static inline void call_on_stack(void *func, void *stack,
-				 unsigned long arg1, void *arg2)
+static char softirq_stack[NR_CPUS * THREAD_SIZE]
+		__attribute__((__section__(".bss.page_aligned")));
+
+static char hardirq_stack[NR_CPUS * THREAD_SIZE]
+		__attribute__((__section__(".bss.page_aligned")));
+
+static void call_on_stack(void *func, void *stack)
 {
-	unsigned long bx;
-
-	asm volatile(
-			"	xchgl  %%ebx,%%esp    \n"
-			"	call   *%%edi	      \n"
-			"	movl   %%ebx,%%esp    \n"
-			: "=a" (arg1), "=d" (arg2), "=b" (bx)
-			:  "0" (arg1),	 "1" (arg2),  "2" (stack),
-			   "D" (func)
-			: "memory", "cc", "ecx");
+	asm volatile("xchgl	%%ebx,%%esp	\n"
+		     "call	*%%edi		\n"
+		     "movl	%%ebx,%%esp	\n"
+		     : "=b" (stack)
+		     : "0" (stack),
+		       "D"(func)
+		     : "memory", "cc", "edx", "ecx", "eax");
 }
 
 static inline int
 execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq)
 {
 	union irq_ctx *curctx, *irqctx;
-	u32 *isp;
+	u32 *isp, arg1, arg2;
 
 	curctx = (union irq_ctx *) current_thread_info();
 	irqctx = hardirq_ctx[smp_processor_id()];
@@ -130,64 +132,22 @@ execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq)
 		(curctx->tinfo.preempt_count & SOFTIRQ_MASK);
 
 	if (unlikely(overflow))
-		call_on_stack(print_stack_overflow, isp, 0, NULL);
-
-	call_on_stack(desc->handle_irq, isp, irq, desc);
-
-	return 1;
-}
-
-#else
-static inline int
-execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq) { return 0; }
-#endif
-
-/*
- * 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 */
-	int overflow, irq = ~regs->orig_ax;
-	struct irq_desc *desc = irq_desc + irq;
-
-	if (unlikely((unsigned)irq >= NR_IRQS)) {
-		printk(KERN_EMERG "%s: cannot handle IRQ %d\n",
-					__func__, irq);
-		BUG();
-	}
-
-	old_regs = set_irq_regs(regs);
-	irq_enter();
-
-	overflow = check_stack_overflow();
-
-	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);
+		call_on_stack(print_stack_overflow, isp);
+
+	asm volatile("xchgl	%%ebx,%%esp	\n"
+		     "call	*%%edi		\n"
+		     "movl	%%ebx,%%esp	\n"
+		     : "=a" (arg1), "=d" (arg2), "=b" (isp)
+		     :  "0" (irq),   "1" (desc),  "2" (isp),
+			"D" (desc->handle_irq)
+		     : "memory", "cc", "ecx");
 	return 1;
 }
 
-#ifdef CONFIG_4KSTACKS
-
-static char softirq_stack[NR_CPUS * THREAD_SIZE]
-		__attribute__((__section__(".bss.page_aligned")));
-
-static char hardirq_stack[NR_CPUS * THREAD_SIZE]
-		__attribute__((__section__(".bss.page_aligned")));
-
 /*
  * allocate per-cpu stacks for hardirq and for softirq processing
  */
-void irq_ctx_init(int cpu)
+void __cpuinit irq_ctx_init(int cpu)
 {
 	union irq_ctx *irqctx;
 
@@ -195,25 +155,25 @@ void irq_ctx_init(int cpu)
 		return;
 
 	irqctx = (union irq_ctx*) &hardirq_stack[cpu*THREAD_SIZE];
-	irqctx->tinfo.task              = NULL;
-	irqctx->tinfo.exec_domain       = NULL;
-	irqctx->tinfo.cpu               = cpu;
-	irqctx->tinfo.preempt_count     = HARDIRQ_OFFSET;
-	irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
+	irqctx->tinfo.task		= NULL;
+	irqctx->tinfo.exec_domain	= NULL;
+	irqctx->tinfo.cpu		= cpu;
+	irqctx->tinfo.preempt_count	= HARDIRQ_OFFSET;
+	irqctx->tinfo.addr_limit	= MAKE_MM_SEG(0);
 
 	hardirq_ctx[cpu] = irqctx;
 
 	irqctx = (union irq_ctx*) &softirq_stack[cpu*THREAD_SIZE];
-	irqctx->tinfo.task              = NULL;
-	irqctx->tinfo.exec_domain       = NULL;
-	irqctx->tinfo.cpu               = cpu;
-	irqctx->tinfo.preempt_count     = 0;
-	irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
+	irqctx->tinfo.task		= NULL;
+	irqctx->tinfo.exec_domain	= NULL;
+	irqctx->tinfo.cpu		= cpu;
+	irqctx->tinfo.preempt_count	= 0;
+	irqctx->tinfo.addr_limit	= MAKE_MM_SEG(0);
 
 	softirq_ctx[cpu] = irqctx;
 
-	printk("CPU %u irqstacks, hard=%p soft=%p\n",
-		cpu,hardirq_ctx[cpu],softirq_ctx[cpu]);
+	printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n",
+	       cpu,hardirq_ctx[cpu],softirq_ctx[cpu]);
 }
 
 void irq_ctx_exit(int cpu)
@@ -242,24 +202,55 @@ asmlinkage void do_softirq(void)
 		/* build the stack frame on the softirq stack */
 		isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
 
-		asm volatile(
-			"       xchgl   %%ebx,%%esp     \n"
-			"       call    __do_softirq    \n"
-			"       movl    %%ebx,%%esp     \n"
-			: "=b"(isp)
-			: "0"(isp)
-			: "memory", "cc", "edx", "ecx", "eax"
-		);
+		call_on_stack(__do_softirq, isp);
 		/*
 		 * Shouldnt happen, we returned above if in_interrupt():
-	 	 */
+		 */
 		WARN_ON_ONCE(softirq_count());
 	}
 
 	local_irq_restore(flags);
 }
+
+#else
+static inline int
+execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq) { return 0; }
 #endif
 
+/*
+ * 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 */
+	int overflow, irq = ~regs->orig_ax;
+	struct irq_desc *desc = irq_desc + irq;
+
+	if (unlikely((unsigned)irq >= NR_IRQS)) {
+		printk(KERN_EMERG "%s: cannot handle IRQ %d\n",
+					__func__, irq);
+		BUG();
+	}
+
+	old_regs = set_irq_regs(regs);
+	irq_enter();
+
+	overflow = check_stack_overflow();
+
+	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;
+}
+
 /*
  * Interrupt statistics:
  */