1*276edc12Sthorpej /* $NetBSD: makecontext.c,v 1.7 2021/07/06 12:38:40 thorpej Exp $ */
23fdac2b8Sthorpej
33fdac2b8Sthorpej /*-
43fdac2b8Sthorpej * Copyright (c) 2001 The NetBSD Foundation, Inc.
53fdac2b8Sthorpej * All rights reserved.
63fdac2b8Sthorpej *
73fdac2b8Sthorpej * This code is derived from software contributed to The NetBSD Foundation
83fdac2b8Sthorpej * by Klaus Klein.
93fdac2b8Sthorpej *
103fdac2b8Sthorpej * Redistribution and use in source and binary forms, with or without
113fdac2b8Sthorpej * modification, are permitted provided that the following conditions
123fdac2b8Sthorpej * are met:
133fdac2b8Sthorpej * 1. Redistributions of source code must retain the above copyright
143fdac2b8Sthorpej * notice, this list of conditions and the following disclaimer.
153fdac2b8Sthorpej * 2. Redistributions in binary form must reproduce the above copyright
163fdac2b8Sthorpej * notice, this list of conditions and the following disclaimer in the
173fdac2b8Sthorpej * documentation and/or other materials provided with the distribution.
183fdac2b8Sthorpej *
193fdac2b8Sthorpej * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
203fdac2b8Sthorpej * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
213fdac2b8Sthorpej * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
223fdac2b8Sthorpej * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
233fdac2b8Sthorpej * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
243fdac2b8Sthorpej * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
253fdac2b8Sthorpej * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
263fdac2b8Sthorpej * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
273fdac2b8Sthorpej * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
283fdac2b8Sthorpej * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
293fdac2b8Sthorpej * POSSIBILITY OF SUCH DAMAGE.
303fdac2b8Sthorpej */
313fdac2b8Sthorpej
323fdac2b8Sthorpej #include <sys/cdefs.h>
333fdac2b8Sthorpej #if defined(LIBC_SCCS) && !defined(lint)
34*276edc12Sthorpej __RCSID("$NetBSD: makecontext.c,v 1.7 2021/07/06 12:38:40 thorpej Exp $");
353fdac2b8Sthorpej #endif
363fdac2b8Sthorpej
373fdac2b8Sthorpej #include <stddef.h>
383fdac2b8Sthorpej #include <inttypes.h>
393fdac2b8Sthorpej #include <ucontext.h>
403fdac2b8Sthorpej #include "extern.h"
413fdac2b8Sthorpej
423fdac2b8Sthorpej #include <stdarg.h>
433fdac2b8Sthorpej
4439079c5fSjoerg void __resumecontext(void) __dead;
4539079c5fSjoerg
463fdac2b8Sthorpej void
makecontext(ucontext_t * ucp,void (* func)(void),int argc,...)473fdac2b8Sthorpej makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
483fdac2b8Sthorpej {
493fdac2b8Sthorpej __greg_t *gr = ucp->uc_mcontext.__gregs;
503fdac2b8Sthorpej int i;
513fdac2b8Sthorpej unsigned long *sp;
523fdac2b8Sthorpej va_list ap;
533fdac2b8Sthorpej
54*276edc12Sthorpej /* Compute stack pointer. */
553fdac2b8Sthorpej sp = (unsigned long *)
56*276edc12Sthorpej ((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
573fdac2b8Sthorpej /* Allocate necessary stack space for arguments exceeding a0-5. */
583fdac2b8Sthorpej if (argc > 6)
593fdac2b8Sthorpej sp -= (argc - 6);
60*276edc12Sthorpej /* Align stack pointer. */
61*276edc12Sthorpej sp = (unsigned long *)((uintptr_t)sp & ~0xfUL);
623fdac2b8Sthorpej gr[_REG_SP] = (__greg_t)sp;
633fdac2b8Sthorpej /* Arrange for return via the trampoline code. */
649560ce9bSdrochner gr[_REG_RA] = (__greg_t)__resumecontext;
653fdac2b8Sthorpej gr[_REG_PC] = (__greg_t)func;
663fdac2b8Sthorpej gr[_REG_PV] = (__greg_t)func;
673fdac2b8Sthorpej
683fdac2b8Sthorpej va_start(ap, argc);
693fdac2b8Sthorpej /* Pass up to six arguments in a0-5. */
703fdac2b8Sthorpej for (i = 0; i < argc && i < 6; i++)
713fdac2b8Sthorpej gr[_REG_A0 + i] = va_arg(ap, unsigned long);
723fdac2b8Sthorpej /* Pass any additional arguments on the stack. */
733fdac2b8Sthorpej for (argc -= i; argc > 0; argc--)
743fdac2b8Sthorpej *sp++ = va_arg(ap, unsigned long);
753fdac2b8Sthorpej va_end(ap);
763fdac2b8Sthorpej }
77