linux-kernel - [PATCH] powerpc/32: Fix unpaired stwcx. on interrupt exit

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Message-ID: <465f323523f677816cc4f26d5e988279a277a37d.1756304342.git.christophe.leroy@csgroup.eu>
Date: Wed, 27 Aug 2025 16:19:14 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Madhavan Srinivasan <maddy@...ux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@...roup.eu>,
	linux-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH] powerpc/32: Fix unpaired stwcx. on interrupt exit

Commit b64f87c16f3c ("[POWERPC] Avoid unpaired stwcx. on some
processors") erroneouly copied to powerpc/32 the logic from powerpc/64
based on feature CPU_FTR_STCX_CHECKS_ADDRESS which is always 0 on
powerpc/32.

Re-instate the logic implemented by commit b64f87c16f3c ("[POWERPC]
Avoid unpaired stwcx. on some processors")

Fixes: b96bae3ae2cb ("powerpc/32: Replace ASM exception exit by C exception exit from ppc64")
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/kernel/entry_32.S | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 762df811433c..c37480176a1c 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -260,10 +260,9 @@ interrupt_return:
 	mtspr	SPRN_SRR1,r12
 
 BEGIN_FTR_SECTION
+	lwarx   r0,0,r1
+END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
 	stwcx.	r0,0,r1		/* to clear the reservation */
-FTR_SECTION_ELSE
-	lwarx	r0,0,r1
-ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
 
 	lwz	r3,_CCR(r1)
 	lwz	r4,_LINK(r1)
@@ -303,10 +302,9 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
 	mtspr	SPRN_SRR1,r12
 
 BEGIN_FTR_SECTION
+	lwarx   r0,0,r1
+END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
 	stwcx.	r0,0,r1		/* to clear the reservation */
-FTR_SECTION_ELSE
-	lwarx	r0,0,r1
-ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
 
 	lwz	r3,_LINK(r1)
 	lwz	r4,_CTR(r1)
-- 
2.49.0