arm/gen/makecontext.c

1.3.8.2  martin /*	$NetBSD: makecontext.c,v 1.3.8.2 2008/04/28 20:22:56 martin Exp $	*/
1.3.8.2  martin
1.3.8.2  martin /*-
1.3.8.2  martin  * Copyright (c) 2001 The NetBSD Foundation, Inc.
1.3.8.2  martin  * All rights reserved.
1.3.8.2  martin  *
1.3.8.2  martin  * This code is derived from software contributed to The NetBSD Foundation
1.3.8.2  martin  * by Klaus Klein.
1.3.8.2  martin  *
1.3.8.2  martin  * Redistribution and use in source and binary forms, with or without
1.3.8.2  martin  * modification, are permitted provided that the following conditions
1.3.8.2  martin  * are met:
1.3.8.2  martin  * 1. Redistributions of source code must retain the above copyright
1.3.8.2  martin  *    notice, this list of conditions and the following disclaimer.
1.3.8.2  martin  * 2. Redistributions in binary form must reproduce the above copyright
1.3.8.2  martin  *    notice, this list of conditions and the following disclaimer in the
1.3.8.2  martin  *    documentation and/or other materials provided with the distribution.
1.3.8.2  martin  *
1.3.8.2  martin  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
1.3.8.2  martin  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
1.3.8.2  martin  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
1.3.8.2  martin  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
1.3.8.2  martin  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
1.3.8.2  martin  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
1.3.8.2  martin  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
1.3.8.2  martin  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
1.3.8.2  martin  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
1.3.8.2  martin  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
1.3.8.2  martin  * POSSIBILITY OF SUCH DAMAGE.
1.3.8.2  martin  */
1.3.8.2  martin
1.3.8.2  martin #include <sys/cdefs.h>
1.3.8.2  martin #if defined(LIBC_SCCS) && !defined(lint)
1.3.8.2  martin __RCSID("$NetBSD: makecontext.c,v 1.3.8.2 2008/04/28 20:22:56 martin Exp $");
1.3.8.2  martin #endif
1.3.8.2  martin
1.3.8.2  martin #include <stddef.h>
1.3.8.2  martin #include <inttypes.h>
1.3.8.2  martin #include <ucontext.h>
1.3.8.2  martin #include "extern.h"
1.3.8.2  martin
1.3.8.2  martin #include <stdarg.h>
1.3.8.2  martin
1.3.8.2  martin void
1.3.8.2  martin makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
1.3.8.2  martin {
1.3.8.2  martin 	__greg_t *gr = ucp->uc_mcontext.__gregs;
1.3.8.2  martin 	int i;
1.3.8.2  martin 	unsigned int *sp;
1.3.8.2  martin 	va_list ap;
1.3.8.2  martin
1.3.8.2  martin 	/* Compute and align stack pointer. */
1.3.8.2  martin 	sp = (unsigned int *)
1.3.8.2  martin 	    (((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size) & ~7);
1.3.8.2  martin 	/* Allocate necessary stack space for arguments exceeding r0-3. */
1.3.8.2  martin 	if (argc > 4)
1.3.8.2  martin 		sp -= argc - 4;
1.3.8.2  martin 	gr[_REG_SP] = (__greg_t)sp;
1.3.8.2  martin 	/* Wipe out frame pointer. */
1.3.8.2  martin 	gr[_REG_FP] = 0;
1.3.8.2  martin 	/* Arrange for return via the trampoline code. */
1.3.8.2  martin 	gr[_REG_LR] = (__greg_t)_resumecontext;
1.3.8.2  martin 	gr[_REG_PC] = (__greg_t)func;
1.3.8.2  martin
1.3.8.2  martin 	va_start(ap, argc);
1.3.8.2  martin 	/* Pass up to four arguments in r0-3. */
1.3.8.2  martin 	for (i = 0; i < argc && i < 4; i++)
1.3.8.2  martin 		gr[_REG_R0 + i] = va_arg(ap, int);
1.3.8.2  martin 	/* Pass any additional arguments on the stack. */
1.3.8.2  martin 	for (argc -= i; argc > 0; argc--)
1.3.8.2  martin 		*sp++ = va_arg(ap, int);
1.3.8.2  martin 	va_end(ap);
1.3.8.2  martin }