1/* $NetBSD: __vfork14.S,v 1.4 2004/07/01 06:50:04 skrll Exp $ */ 2 3/*- 4 * Copyright (c) 2001 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Matt Fredette. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39#include <sys/errno.h> 40#include "SYS.h" 41 42ENTRY(__vfork14, 0) 43 /* 44 * NB: __vfork14 is a tricky syscall. We can't save 45 * any values on the stack, because the stack will be 46 * trashed by the child, leaving garbage for when the 47 * parent returns. 48 * 49 * So we must save values in registers, specifically, 50 * registers that the kernel is willing to preserve 51 * across the syscall. Normally, this would be callee- 52 * saved registers, with the kernel being the callee, 53 * but the problem is that we, too, are a callee, and 54 * would have to save that very same register somewhere, 55 * because *our* caller is counting on us to do so. 56 * 57 * What we need is a normally caller-saved register, 58 * that the kernel is willing to save for us. The 59 * syscall entry code in locore.S has been modified 60 * to do just this for the t4 register. 61 */ 62 .import __cerror, code 63 64 copy %rp, %t4 65 ldil L%SYSCALLGATE, %r1 66 ble 4(%sr7, %r1) 67 ldi SYS___vfork14, %t1 68 comb,<> %r0, %t1, __cerror 69 copy %t4, %rp 70 addi -1, %ret1, %ret1 71 bv %r0(%rp) 72 and %ret0, %ret1, %ret0 73EXIT(__vfork14) 74