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- /* 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 */
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