powerpc: Add new kconfig CONFIG_PPC_IRQ_SOFT_MASK_DEBUG

New Kconfig is added "CONFIG_PPC_IRQ_SOFT_MASK_DEBUG" to add WARN_ON
to alert the invalid transitions. Also moved the code under the
CONFIG_TRACE_IRQFLAGS in arch_local_irq_restore() to new Kconfig.
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
[mpe: Fix name of CONFIG option in change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/Kconfig.debug

@@ -90,6 +90,10 @@ config MSI_BITMAP_SELFTEST
 	depends on DEBUG_KERNEL
 	default n
 
+config PPC_IRQ_SOFT_MASK_DEBUG
+	bool "Include extra checks for powerpc irq soft masking"
+	default n
+
 config XMON
 	bool "Include xmon kernel debugger"
 	depends on DEBUG_KERNEL

arch/powerpc/include/asm/hw_irq.h

@@ -71,7 +71,7 @@ static inline notrace unsigned long irq_soft_mask_return(void)
  */
 static inline notrace void irq_soft_mask_set(unsigned long mask)
 {
-#ifdef CONFIG_TRACE_IRQFLAGS
+#ifdef CONFIG_PPC_IRQ_SOFT_MASK_DEBUG
 	/*
 	 * The irq mask must always include the STD bit if any are set.
 	 *
@@ -101,7 +101,7 @@ static inline notrace unsigned long irq_soft_mask_set_return(unsigned long mask)
 {
 	unsigned long flags;
 
-#ifdef CONFIG_TRACE_IRQFLAGS
+#ifdef CONFIG_PPC_IRQ_SOFT_MASK_DEBUG
 	WARN_ON(mask && !(mask & IRQS_DISABLED));
 #endif
 

arch/powerpc/kernel/entry_64.S

@@ -128,7 +128,7 @@ END_FW_FTR_SECTION_IFSET(FW_FEATURE_SPLPAR)
 	 * of irq tracing is used, we additionally check that condition
 	 * is correct
 	 */
-#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_BUG)
+#if defined(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG) && defined(CONFIG_BUG)
 	lbz	r10,PACAIRQSOFTMASK(r13)
 1:	tdnei	r10,IRQS_ENABLED
 	EMIT_BUG_ENTRY 1b,__FILE__,__LINE__,BUGFLAG_WARNING
@@ -911,7 +911,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 	rlwinm	r7,r7,0,~PACA_IRQ_HARD_DIS
 	stb	r7,PACAIRQHAPPENED(r13)
 1:
-#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_BUG)
+#if defined(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG) && defined(CONFIG_BUG)
 	/* The interrupt should not have soft enabled. */
 	lbz	r7,PACAIRQSOFTMASK(r13)
 1:	tdeqi	r7,IRQS_ENABLED

arch/powerpc/kernel/irq.c

@@ -264,7 +264,7 @@ notrace void arch_local_irq_restore(unsigned long mask)
 	 */
 	if (unlikely(irq_happened != PACA_IRQ_HARD_DIS))
 		__hard_irq_disable();
-#ifdef CONFIG_TRACE_IRQFLAGS
+#ifdef CONFIG_PPC_IRQ_SOFT_MASK_DEBUG
 	else {
 		/*
 		 * We should already be hard disabled here. We had bugs
@@ -275,7 +275,7 @@ notrace void arch_local_irq_restore(unsigned long mask)
 		if (WARN_ON(mfmsr() & MSR_EE))
 			__hard_irq_disable();
 	}
-#endif /* CONFIG_TRACE_IRQFLAGS */
+#endif
 
 	irq_soft_mask_set(IRQS_ALL_DISABLED);
 	trace_hardirqs_off();