[linux-block.git] / arch / h8300 / include / asm / switch_to.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _H8300_SWITCH_TO_H
#define _H8300_SWITCH_TO_H

/*
 * switch_to(n) should switch tasks to task ptr, first checking that
 * ptr isn't the current task, in which case it does nothing.  This
 * also clears the TS-flag if the task we switched to has used the
 * math co-processor latest.
 */
/*
 * switch_to() saves the extra registers, that are not saved
 * automatically by SAVE_SWITCH_STACK in resume(), ie. d0-d5 and
 * a0-a1. Some of these are used by schedule() and its predecessors
 * and so we might get see unexpected behaviors when a task returns
 * with unexpected register values.
 *
 * syscall stores these registers itself and none of them are used
 * by syscall after the function in the syscall has been called.
 *
 * Beware that resume now expects *next to be in d1 and the offset of
 * tss to be in a1. This saves a few instructions as we no longer have
 * to push them onto the stack and read them back right after.
 *
 * 02/17/96 - Jes Sorensen (jds@kom.auc.dk)
 *
 * Changed 96/09/19 by Andreas Schwab
 * pass prev in a0, next in a1, offset of tss in d1, and whether
 * the mm structures are shared in d2 (to avoid atc flushing).
 *
 * H8/300 Porting 2002/09/04 Yoshinori Sato
 */

asmlinkage void resume(void);
#define switch_to(prev, next, last) \
do {			     \
	void *_last;					    \
	__asm__ __volatile__(				    \
		"mov.l	%1, er0\n\t"			    \
		"mov.l	%2, er1\n\t"			    \
		"mov.l	%3, er2\n\t"			    \
		"jsr @_resume\n\t"			    \
		"mov.l	er2,%0\n\t"			    \
		: "=r" (_last)				    \
		: "r" (&(prev->thread)),		    \
		  "r" (&(next->thread)),		    \
		  "g" (prev)				    \
		: "cc", "er0", "er1", "er2", "er3");	    \
	(last) = _last;					    \
} while (0)

#endif /* _H8300_SWITCH_TO_H */
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
d2a5f499 YS	2	#ifndef _H8300_SWITCH_TO_H
	3	#define _H8300_SWITCH_TO_H
	4
	5	/*
	6	* switch_to(n) should switch tasks to task ptr, first checking that
	7	* ptr isn't the current task, in which case it does nothing. This
	8	* also clears the TS-flag if the task we switched to has used the
	9	* math co-processor latest.
	10	*/
	11	/*
	12	* switch_to() saves the extra registers, that are not saved
	13	* automatically by SAVE_SWITCH_STACK in resume(), ie. d0-d5 and
	14	* a0-a1. Some of these are used by schedule() and its predecessors
	15	* and so we might get see unexpected behaviors when a task returns
	16	* with unexpected register values.
	17	*
	18	* syscall stores these registers itself and none of them are used
	19	* by syscall after the function in the syscall has been called.
	20	*
	21	* Beware that resume now expects *next to be in d1 and the offset of
	22	* tss to be in a1. This saves a few instructions as we no longer have
	23	* to push them onto the stack and read them back right after.
	24	*
	25	* 02/17/96 - Jes Sorensen (jds@kom.auc.dk)
	26	*
	27	* Changed 96/09/19 by Andreas Schwab
	28	* pass prev in a0, next in a1, offset of tss in d1, and whether
	29	* the mm structures are shared in d2 (to avoid atc flushing).
	30	*
	31	* H8/300 Porting 2002/09/04 Yoshinori Sato
	32	*/
	33
	34	asmlinkage void resume(void);
	35	#define switch_to(prev, next, last) \
	36	do { \
	37	void *_last; \
	38	__asm__ __volatile__( \
	39	"mov.l %1, er0\n\t" \
	40	"mov.l %2, er1\n\t" \
	41	"mov.l %3, er2\n\t" \
	42	"jsr @_resume\n\t" \
	43	"mov.l er2,%0\n\t" \
	44	: "=r" (_last) \
	45	: "r" (&(prev->thread)), \
	46	"r" (&(next->thread)), \
	47	"g" (prev) \
	48	: "cc", "er0", "er1", "er2", "er3"); \
	49	(last) = _last; \
	50	} while (0)
	51
	52	#endif /* _H8300_SWITCH_TO_H */