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s390: fine-tune stack switch helper

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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>
This commit is contained in:
Martin Schwidefsky 2019-04-10 15:48:43 +02:00
parent e24e4712ef
commit 7aa0055e06
1 changed files with 9 additions and 9 deletions
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18
arch/s390/include/asm/processor.h
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@ -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; \
})