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