hppa/sys/__vfork14.S

1.5.8.2  martin /*	$NetBSD: __vfork14.S,v 1.5.8.2 2008/04/28 20:22:57 martin Exp $	*/
1.5.8.2  martin
1.5.8.2  martin /*-
1.5.8.2  martin  * Copyright (c) 2001 The NetBSD Foundation, Inc.
1.5.8.2  martin  * All rights reserved.
1.5.8.2  martin  *
1.5.8.2  martin  * This code is derived from software contributed to The NetBSD Foundation
1.5.8.2  martin  * by Matt Fredette.
1.5.8.2  martin  *
1.5.8.2  martin  * Redistribution and use in source and binary forms, with or without
1.5.8.2  martin  * modification, are permitted provided that the following conditions
1.5.8.2  martin  * are met:
1.5.8.2  martin  * 1. Redistributions of source code must retain the above copyright
1.5.8.2  martin  *    notice, this list of conditions and the following disclaimer.
1.5.8.2  martin  * 2. Redistributions in binary form must reproduce the above copyright
1.5.8.2  martin  *    notice, this list of conditions and the following disclaimer in the
1.5.8.2  martin  *    documentation and/or other materials provided with the distribution.
1.5.8.2  martin  *
1.5.8.2  martin  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
1.5.8.2  martin  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
1.5.8.2  martin  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
1.5.8.2  martin  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
1.5.8.2  martin  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
1.5.8.2  martin  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
1.5.8.2  martin  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
1.5.8.2  martin  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
1.5.8.2  martin  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
1.5.8.2  martin  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
1.5.8.2  martin  * POSSIBILITY OF SUCH DAMAGE.
1.5.8.2  martin  */
1.5.8.2  martin
1.5.8.2  martin #include <sys/errno.h>
1.5.8.2  martin #include "SYS.h"
1.5.8.2  martin
1.5.8.2  martin ENTRY(__vfork14, 0)
1.5.8.2  martin 	/*
1.5.8.2  martin 	 * NB: __vfork14 is a tricky syscall.  We can't save
1.5.8.2  martin 	 * any values on the stack, because the stack will be
1.5.8.2  martin 	 * trashed by the child, leaving garbage for when the
1.5.8.2  martin 	 * parent returns.
1.5.8.2  martin 	 *
1.5.8.2  martin 	 * So we must save values in registers, specifically,
1.5.8.2  martin 	 * registers that the kernel is willing to preserve
1.5.8.2  martin 	 * across the syscall.  Normally, this would be callee-
1.5.8.2  martin 	 * saved registers, with the kernel being the callee,
1.5.8.2  martin 	 * but the problem is that we, too, are a callee, and
1.5.8.2  martin 	 * would have to save that very same register somewhere,
1.5.8.2  martin 	 * because *our* caller is counting on us to do so.
1.5.8.2  martin 	 *
1.5.8.2  martin 	 * What we need is a normally caller-saved register,
1.5.8.2  martin 	 * that the kernel is willing to save for us.  The
1.5.8.2  martin 	 * syscall entry code in locore.S has been modified
1.5.8.2  martin 	 * to do just this for the t4 register.
1.5.8.2  martin 	 */
1.5.8.2  martin 	.import	__cerror, code
1.5.8.2  martin
1.5.8.2  martin 	copy	%rp, %t4
1.5.8.2  martin 	ldil	L%SYSCALLGATE, %r1
1.5.8.2  martin 	ble	4(%sr7, %r1)
1.5.8.2  martin 	ldi	SYS___vfork14, %t1
1.5.8.2  martin 	comb,<>	%r0, %t1, __cerror
1.5.8.2  martin 	copy	%t4, %rp
1.5.8.2  martin 	addi	-1, %ret1, %ret1
1.5.8.2  martin 	bv	%r0(%rp)
1.5.8.2  martin 	and	%ret0, %ret1, %ret0
1.5.8.2  martin EXIT(__vfork14)