1/* $NetBSD: __vfork14.S,v 1.2 2002/07/01 16:00:52 fredette 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 42 .import errno, data 43 44ENTRY(__vfork14, 0) 45 /* 46 * NB: __vfork14 is a tricky syscall. We can't save 47 * any values on the stack, because the stack will be 48 * trashed by the child, leaving garbage for when the 49 * parent returns. 50 * 51 * So we must save values in registers, specifically, 52 * registers that the kernel is willing to preserve 53 * across the syscall. Normally, this would be callee- 54 * saved registers, with the kernel being the callee, 55 * but the problem is that we, too, are a callee, and 56 * would have to save that very same register somewhere, 57 * because *our* caller is counting on us to do so. 58 * 59 * What we need is a normally caller-saved register, 60 * that the kernel is willing to save for us. The 61 * syscall entry code in locore.S has been modified 62 * to do just this for the t4 register. 63 */ 64 .import errno, data 65 copy rp, t4 66 ldil L%SYSCALLGATE, r1 67 ble 4(sr7, r1) 68 ldi SYS___vfork14, t1 69 copy t4, rp 70 comb,=,n r0, t1, __vfork14$noerr 71 __SYSCALL_ERRNO 72 ldi -1, ret0 73 bv r0(rp) 74 ldi -1, ret1 75__vfork14$noerr 76 addi -1, ret1, ret1 77 bv r0(rp) 78 and ret0, ret1, ret0 79EXIT(__vfork14) 80