1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
4  */
5 #ifndef _ASM_SWITCH_TO_H
6 #define _ASM_SWITCH_TO_H
7 
8 #include <asm/cpu-features.h>
9 #include <asm/fpu.h>
10 
11 struct task_struct;
12 
13 /**
14  * __switch_to - switch execution of a task
15  * @prev:	The task previously executed.
16  * @next:	The task to begin executing.
17  * @next_ti:	task_thread_info(next).
18  * @sched_ra:	__schedule return address.
19  * @sched_cfa:	__schedule call frame address.
20  *
21  * This function is used whilst scheduling to save the context of prev & load
22  * the context of next. Returns prev.
23  */
24 extern asmlinkage struct task_struct *__switch_to(struct task_struct *prev,
25 			struct task_struct *next, struct thread_info *next_ti,
26 			void *sched_ra, void *sched_cfa);
27 
28 /*
29  * For newly created kernel threads switch_to() will return to
30  * ret_from_kernel_thread, newly created user threads to ret_from_fork.
31  * That is, everything following __switch_to() will be skipped for new threads.
32  * So everything that matters to new threads should be placed before __switch_to().
33  */
34 #define switch_to(prev, next, last)						\
35 do {										\
36 	lose_fpu_inatomic(1, prev);						\
37 	(last) = __switch_to(prev, next, task_thread_info(next),		\
38 		 __builtin_return_address(0), __builtin_frame_address(0));	\
39 } while (0)
40 
41 #endif /* _ASM_SWITCH_TO_H */
42