From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Date: Wed, 10 Apr 2019 15:48:43 +0200
Subject: s390: fine-tune stack switch helper
Git-commit: 7aa0055e06475f7b486c0673bc59c6478bc055fa
Patch-mainline: v5.2-rc1
References: jsc#SLE-11178
The CALL_ON_STACK helper currently does not work with clang and for
calls without arguments. It does not initialize r2 although the constraint
is "+&d". Rework the CALL_FMT_x and the CALL_ON_STACK macros to work
with clang and produce optimal code in all cases.
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
---
arch/s390/include/asm/processor.h | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index 81038ab357ce..0ee022247580 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -261,12 +261,12 @@ static __no_kasan_or_inline unsigned short stap(void)
CALL_ARGS_4(arg1, arg2, arg3, arg4); \
register unsigned long r4 asm("6") = (unsigned long)(arg5)
-#define CALL_FMT_0
-#define CALL_FMT_1 CALL_FMT_0, "0" (r2)
-#define CALL_FMT_2 CALL_FMT_1, "d" (r3)
-#define CALL_FMT_3 CALL_FMT_2, "d" (r4)
-#define CALL_FMT_4 CALL_FMT_3, "d" (r5)
-#define CALL_FMT_5 CALL_FMT_4, "d" (r6)
+#define CALL_FMT_0 "=&d" (r2) :
+#define CALL_FMT_1 "+&d" (r2) :
+#define CALL_FMT_2 CALL_FMT_1 "d" (r3),
+#define CALL_FMT_3 CALL_FMT_2 "d" (r4),
+#define CALL_FMT_4 CALL_FMT_3 "d" (r5),
+#define CALL_FMT_5 CALL_FMT_4 "d" (r6),
#define CALL_CLOBBER_5 "0", "1", "14", "cc", "memory"
#define CALL_CLOBBER_4 CALL_CLOBBER_5
@@ -286,10 +286,10 @@ static __no_kasan_or_inline unsigned short stap(void)
" stg %[_prev],%[_bc](15)\n" \
" brasl 14,%[_fn]\n" \
" la 15,0(%[_prev])\n" \
- : "+&d" (r2), [_prev] "=&a" (prev) \
- : [_stack] "a" (stack), \
+ : [_prev] "=&a" (prev), CALL_FMT_##nr \
+ [_stack] "a" (stack), \
[_bc] "i" (offsetof(struct stack_frame, back_chain)), \
- [_fn] "X" (fn) CALL_FMT_##nr : CALL_CLOBBER_##nr); \
+ [_fn] "X" (fn) : CALL_CLOBBER_##nr); \
r2; \
})