diff mbox series

[1/2] powerpc/64/interrupt: avoid BUG/WARN recursion in interrupt entry

Message ID 20220907120347.3684283-2-npiggin@gmail.com (mailing list archive)
State Superseded
Headers show
Series powerpc/64: more soft-mask improvements | expand

Commit Message

Nicholas Piggin Sept. 7, 2022, 12:03 p.m. UTC 
BUG/WARN are handled with a program interrupt which can turn into an
infinite recursion when there are bugs in interrupt handler entry
(which can be irritated by bugs in other parts of the code).

There is one feeble attempt to avoid this recursion, but it misses
several cases. Make a tidier macro for this and switch most bugs in
the interrupt entry wrapper over to use it.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/include/asm/interrupt.h | 33 +++++++++++++++++-----------
 1 file changed, 20 insertions(+), 13 deletions(-)
diff mbox series

Patch

diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h
index 8069dbc4b8d1..690ca27d8dd1 100644
--- a/arch/powerpc/include/asm/interrupt.h
+++ b/arch/powerpc/include/asm/interrupt.h
@@ -74,6 +74,19 @@ 
 #include <asm/kprobes.h>
 #include <asm/runlatch.h>
 
+#ifdef CONFIG_PPC64
+/*
+ * WARN/BUG is handled with a program interrupt so minimise checks here to
+ * avoid recursion and maximise the chance of getting the first oops handled.
+ */
+#define INT_SOFT_MASK_BUG_ON(regs, cond)				\
+do {									\
+	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG) &&		\
+	    (user_mode(regs) || (TRAP(regs) != INTERRUPT_PROGRAM)))	\
+		BUG_ON(cond);						\
+} while (0)
+#endif
+
 #ifdef CONFIG_PPC_BOOK3S_64
 extern char __end_soft_masked[];
 bool search_kernel_soft_mask_table(unsigned long addr);
@@ -170,8 +183,7 @@  static inline void interrupt_enter_prepare(struct pt_regs *regs)
 	 * context.
 	 */
 	if (!(local_paca->irq_happened & PACA_IRQ_HARD_DIS)) {
-		if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
-			BUG_ON(!(regs->msr & MSR_EE));
+		INT_SOFT_MASK_BUG_ON(regs, !(regs->msr & MSR_EE));
 		__hard_irq_enable();
 	} else {
 		__hard_RI_enable();
@@ -194,19 +206,14 @@  static inline void interrupt_enter_prepare(struct pt_regs *regs)
 		 * CT_WARN_ON comes here via program_check_exception,
 		 * so avoid recursion.
 		 */
-		if (TRAP(regs) != INTERRUPT_PROGRAM) {
+		if (TRAP(regs) != INTERRUPT_PROGRAM)
 			CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
-			if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
-				BUG_ON(is_implicit_soft_masked(regs));
-		}
-
-		/* Move this under a debugging check */
-		if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG) &&
-				arch_irq_disabled_regs(regs))
-			BUG_ON(search_kernel_restart_table(regs->nip));
+		INT_SOFT_MASK_BUG_ON(regs, is_implicit_soft_masked(regs));
+		INT_SOFT_MASK_BUG_ON(regs, arch_irq_disabled_regs(regs) &&
+					   search_kernel_restart_table(regs->nip));
 	}
-	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
-		BUG_ON(!arch_irq_disabled_regs(regs) && !(regs->msr & MSR_EE));
+	INT_SOFT_MASK_BUG_ON(regs, !arch_irq_disabled_regs(regs) &&
+				   !(regs->msr & MSR_EE));
 #endif
 
 	booke_restore_dbcr0();