From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 11 Apr 2024 10:27:49 +0200 Subject: Adding upstream version 6.6.15. Signed-off-by: Daniel Baumann --- arch/m68k/include/asm/switch_to.h | 42 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 arch/m68k/include/asm/switch_to.h (limited to 'arch/m68k/include/asm/switch_to.h') diff --git a/arch/m68k/include/asm/switch_to.h b/arch/m68k/include/asm/switch_to.h new file mode 100644 index 0000000000..94f02f46c5 --- /dev/null +++ b/arch/m68k/include/asm/switch_to.h @@ -0,0 +1,42 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#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 */ -- cgit v1.2.3