803f69144f
Disintegrate asm/system.h for M68K. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Greg Ungerer <gerg@uclinux.org> cc: linux-m68k@lists.linux-m68k.org
41 lines
1.5 KiB
C
41 lines
1.5 KiB
C
#ifndef _M68K_SWITCH_TO_H
|
|
#define _M68K_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
|
|
*/
|
|
asmlinkage void resume(void);
|
|
#define switch_to(prev,next,last) do { \
|
|
register void *_prev __asm__ ("a0") = (prev); \
|
|
register void *_next __asm__ ("a1") = (next); \
|
|
register void *_last __asm__ ("d1"); \
|
|
__asm__ __volatile__("jbsr resume" \
|
|
: "=a" (_prev), "=a" (_next), "=d" (_last) \
|
|
: "0" (_prev), "1" (_next) \
|
|
: "d0", "d2", "d3", "d4", "d5"); \
|
|
(last) = _last; \
|
|
} while (0)
|
|
|
|
#endif /* _M68K_SWITCH_TO_H */
|