From 4ea212dc84e476e14f1fb223d4b41a855338717c Mon Sep 17 00:00:00 2001
From: Nicholas Piggin <npiggin@gmail.com>
Date: Sat, 12 Aug 2017 02:39:01 +1000
Subject: [PATCH] powerpc/64s: masked_interrupt() returns to kernel so avoid
 restoring r13

References: bsc#1068032
Patch-mainline: v4.14-rc1
Git-commit: c05f0be888225f7228f81825730da3c9ba2088cb

Places in the kernel where r13 is not the PACA pointer must have
maskable interrupts disabled, so r13 does not have to be restored when
returning from a soft-masked interrupt. We should never have
interrupts soft disabled when we're in user space.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/kernel/exceptions-64s.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 5892417a024e..17db60294030 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1403,7 +1403,7 @@ masked_##_H##interrupt:					\
 	ld	r9,PACA_EXGEN+EX_R9(r13);		\
 	ld	r10,PACA_EXGEN+EX_R10(r13);		\
 	ld	r11,PACA_EXGEN+EX_R11(r13);		\
-	GET_SCRATCH0(r13);				\
+	/* returns to kernel where r13 must be set up, so don't restore it */ \
 	##_H##rfid;					\
 	b	.
 
-- 
2.13.6