1/* SPDX-License-Identifier: GPL-2.0 */ 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 34asmlinkage void resume(void); 35#define switch_to(prev, next, last) \ 36do { \ 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 */ 53