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a5401ee3 DH |
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 | ||
33 | asmlinkage void resume(void); | |
34 | #define switch_to(prev,next,last) { \ | |
35 | void *_last; \ | |
36 | __asm__ __volatile__( \ | |
37 | "mov.l %1, er0\n\t" \ | |
38 | "mov.l %2, er1\n\t" \ | |
39 | "mov.l %3, er2\n\t" \ | |
40 | "jsr @_resume\n\t" \ | |
41 | "mov.l er2,%0\n\t" \ | |
42 | : "=r" (_last) \ | |
43 | : "r" (&(prev->thread)), \ | |
44 | "r" (&(next->thread)), \ | |
45 | "g" (prev) \ | |
46 | : "cc", "er0", "er1", "er2", "er3"); \ | |
47 | (last) = _last; \ | |
48 | } | |
49 | ||
50 | #endif /* _H8300_SWITCH_TO_H */ |