From: Vasily Gorbik <gor@linux.ibm.com>
Date: Mon, 25 Nov 2019 13:34:59 +0100
Subject: s390: fix register clobbering in CALL_ON_STACK
Git-commit: 4ac24c092b4eef69b2436ee4d478500dc886e8b5
Patch-mainline: v5.5-rc1
References: jsc#SLE-11178

CALL_ON_STACK defines and initializes register variables. Inline
assembly which follows might trigger compiler to generate memory access
for "stack" argument (e.g. in case of S390_lowcore.nodat_stack). This
memory access produces a function call under kasan with outline
instrumentation which clobbers registers.

Switch "stack" argument in CALL_ON_STACK helper to use memory reference
constraint and perform load instead.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
---
 arch/s390/include/asm/stacktrace.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/s390/include/asm/stacktrace.h b/arch/s390/include/asm/stacktrace.h
index 4725315a9cb1..ee056f4a4fa3 100644
--- a/arch/s390/include/asm/stacktrace.h
+++ b/arch/s390/include/asm/stacktrace.h
@@ -112,12 +112,12 @@ struct stack_frame {
 									\
 	asm volatile(							\
 		"	la	%[_prev],0(15)\n"			\
-		"	la	15,0(%[_stack])\n"			\
+		"	lg	15,%[_stack]\n"				\
 		"	stg	%[_frame],%[_bc](15)\n"			\
 		"	brasl	14,%[_fn]\n"				\
 		"	la	15,0(%[_prev])\n"			\
 		: [_prev] "=&a" (prev), CALL_FMT_##nr			\
-		  [_stack] "a" (stack),					\
+		  [_stack] "R" (stack),					\
 		  [_bc] "i" (offsetof(struct stack_frame, back_chain)),	\
 		  [_frame] "d" (frame),					\
 		  [_fn] "X" (fn) : CALL_CLOBBER_##nr);			\