Split the switch_to() wrapper out of asm-generic/system.h

/* Generic task switch macro wrapper, based on MN10300 definitions.

 *

 * It should be possible to use these on really simple architectures,

 * but it serves more as a starting point for new ports.

 *

 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.

 * Written by David Howells (dhowells@redhat.com)

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public Licence

 * as published by the Free Software Foundation; either version

 * 2 of the Licence, or (at your option) any later version.

 */

#ifndef __ASM_GENERIC_SWITCH_TO_H

#define __ASM_GENERIC_SWITCH_TO_H

#include <linux/thread_info.h>

/*

 * Context switching is now performed out-of-line in switch_to.S

 */

extern struct task_struct *__switch_to(struct task_struct *,

				       struct task_struct *);

#define switch_to(prev, next, last)					\

	do {								\

		((last) = __switch_to((prev), (next)));			\

	} while (0)

#endif /* __ASM_GENERIC_SWITCH_TO_H */

#ifndef __ASM_GENERIC_SYSTEM_H

#define __ASM_GENERIC_SYSTEM_H

#ifndef __ASSEMBLY__

#include <linux/types.h>

#include <asm/barrier.h>

#include <asm/cmpxchg.h>

struct task_struct;

/* context switching is now performed out-of-line in switch_to.S */

extern struct task_struct *__switch_to(struct task_struct *,

		struct task_struct *);

#define switch_to(prev, next, last)					\

	do {								\

		((last) = __switch_to((prev), (next)));			\

	} while (0)

#include <asm/switch_to.h>

#define arch_align_stack(x) (x)

#endif /* !__ASSEMBLY__ */

#endif /* __ASM_GENERIC_SYSTEM_H */