xref: /src/lib/libc/arch/hppa/sys/__vfork14.S

/*	$NetBSD: __vfork14.S,v 1.1 2002/06/06 20:31:23 fredette Exp $	*/

/*-
 * Copyright (c) 2001 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Matt Fredette.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *        This product includes software developed by the NetBSD
 *        Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/errno.h>
#include "SYS.h"

	.import errno, data

ENTRY(__vfork14, 0)
	/*
	 * NB: __vfork14 is a tricky syscall.  We can't save
	 * any values on the stack, because the stack will be
	 * trashed by the child, leaving garbage for when the
	 * parent returns.
	 *
	 * So we must save values in registers, specifically,
	 * registers that the kernel is willing to preserve
	 * across the syscall.  Normally, this would be callee-
	 * saved registers, with the kernel being the callee,
	 * but the problem is that we, too, are a callee, and
	 * would have to save that very same register somewhere,
	 * because *our* caller is counting on us to do so.
	 *
	 * What we need is a normally caller-saved register,
	 * that the kernel is willing to save for us.  The
	 * syscall entry code in locore.S has been modified
	 * to do just this for the t4 register.
	 */
	.import	errno, data
	copy	rp, t4
	ldil	L%SYSCALLGATE, r1
	ble	4(sr7, r1)
	ldi	SYS___vfork14, t1
	copy	t4, rp
	comb,=,n r0, t1, __vfork14$noerr
	ldil	L%errno, r1
	stw	t1, R%errno(r1)
	ldi	-1, ret0
	bv	r0(rp)
	ldi	-1, ret1
__vfork14$noerr
	addi	-1, ret1, ret1
	bv	r0(rp)
	and	ret0, ret1, ret0
EXIT(__vfork14)