Commit 7aa0055e authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390: fine-tune stack switch helper 



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: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent e24e4712

arch/s390/include/asm/processor.h

+9 −9
Original line number Diff line number Diff line
@@ -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;								\

})

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