root/arch/s390/include/asm/types.h 
/* SPDX-License-Identifier: GPL-2.0-or-later */

#ifndef _ASM_S390_TYPES_H
#define _ASM_S390_TYPES_H

#include <uapi/asm/types.h>

#ifndef __ASSEMBLER__

union register_pair {
        unsigned __int128 pair;
        struct {
                unsigned long even;
                unsigned long odd;
        };
};

#endif /* __ASSEMBLER__ */
#endif /* _ASM_S390_TYPES_H */