[PATCH 1/2] powerpc/64s/interrupt: Change must-hard-mask interrupt check from BUG to WARN

From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Sachin Sant <sachinp@linux.ibm.com>, Nicholas Piggin <npiggin@gmail.com>
Subject: [PATCH 1/2] powerpc/64s/interrupt: Change must-hard-mask interrupt check from BUG to WARN
Date: Tue,  4 Oct 2022 15:11:56 +1000	[thread overview]
Message-ID: <20221004051157.308999-1-npiggin@gmail.com> (raw)

This new assertion added is generally harmless and gets fixed up
naturally, but it does indicate a problem with MSR manipulation
somewhere.

Fixes: c39fb71a54f0 ("powerpc/64s/interrupt: masked handler debug check for previous hard disable")
Reported-by: Sachin Sant <sachinp@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/kernel/exceptions-64s.S | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index dafa275f18bc..d5d35f3a824e 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -2797,12 +2797,16 @@ masked_interrupt:
 #ifdef CONFIG_PPC_IRQ_SOFT_MASK_DEBUG
 	/*
 	 * Ensure there was no previous MUST_HARD_MASK interrupt or
-	 * HARD_DIS setting.
+	 * HARD_DIS setting. If this does fire, the interrupt is still
+	 * masked and MSR[EE] will be cleared on return, so no need to
+	 * panic, but somebody probably enabled MSR[EE] under
+	 * PACA_IRQ_HARD_DIS, mtmsr(mfmsr() | MSR_x) being a common
+	 * cause.
 	 */
 	lbz	r9,PACAIRQHAPPENED(r13)
 	andi.	r9,r9,(PACA_IRQ_MUST_HARD_MASK|PACA_IRQ_HARD_DIS)
 0:	tdnei	r9,0
-	EMIT_BUG_ENTRY 0b,__FILE__,__LINE__,0
+	EMIT_WARN_ENTRY 0b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
 #endif
 	lbz	r9,PACAIRQHAPPENED(r13)
 	or	r9,r9,r10
-- 
2.37.2

