1 1.10 skrll /* $NetBSD: __vfork14.S,v 1.10 2020/05/09 08:25:33 skrll Exp $ */ 2 1.1 fredette 3 1.1 fredette /*- 4 1.1 fredette * Copyright (c) 2001 The NetBSD Foundation, Inc. 5 1.1 fredette * All rights reserved. 6 1.1 fredette * 7 1.1 fredette * This code is derived from software contributed to The NetBSD Foundation 8 1.1 fredette * by Matt Fredette. 9 1.1 fredette * 10 1.1 fredette * Redistribution and use in source and binary forms, with or without 11 1.1 fredette * modification, are permitted provided that the following conditions 12 1.1 fredette * are met: 13 1.1 fredette * 1. Redistributions of source code must retain the above copyright 14 1.1 fredette * notice, this list of conditions and the following disclaimer. 15 1.1 fredette * 2. Redistributions in binary form must reproduce the above copyright 16 1.1 fredette * notice, this list of conditions and the following disclaimer in the 17 1.1 fredette * documentation and/or other materials provided with the distribution. 18 1.1 fredette * 19 1.1 fredette * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 1.1 fredette * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 1.1 fredette * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 1.1 fredette * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 1.1 fredette * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 1.1 fredette * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 1.1 fredette * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 1.1 fredette * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 1.1 fredette * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 1.1 fredette * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 1.1 fredette * POSSIBILITY OF SUCH DAMAGE. 30 1.1 fredette */ 31 1.1 fredette 32 1.1 fredette #include <sys/errno.h> 33 1.1 fredette #include "SYS.h" 34 1.1 fredette 35 1.1 fredette ENTRY(__vfork14, 0) 36 1.1 fredette /* 37 1.1 fredette * NB: __vfork14 is a tricky syscall. We can't save 38 1.7 skrll * any values on the stack, because the stack will be 39 1.1 fredette * trashed by the child, leaving garbage for when the 40 1.1 fredette * parent returns. 41 1.1 fredette * 42 1.1 fredette * So we must save values in registers, specifically, 43 1.1 fredette * registers that the kernel is willing to preserve 44 1.1 fredette * across the syscall. Normally, this would be callee- 45 1.1 fredette * saved registers, with the kernel being the callee, 46 1.1 fredette * but the problem is that we, too, are a callee, and 47 1.1 fredette * would have to save that very same register somewhere, 48 1.1 fredette * because *our* caller is counting on us to do so. 49 1.1 fredette * 50 1.1 fredette * What we need is a normally caller-saved register, 51 1.7 skrll * that the kernel is willing to save for us. The 52 1.7 skrll * syscall entry code in locore.S has been modified 53 1.1 fredette * to do just this for the t4 register. 54 1.1 fredette */ 55 1.3 matt copy %rp, %t4 56 1.3 matt ldil L%SYSCALLGATE, %r1 57 1.6 skrll ble 4(%sr2, %r1) 58 1.9 skrll ldi SYS___vfork14, %t1 59 1.9 skrll comb,=,n %r0, %t1, 1f 60 1.9 skrll b __cerror 61 1.9 skrll 1: 62 1.9 skrll copy %t4, %rp // delay slot of branch to __cerror 63 1.3 matt addi -1, %ret1, %ret1 64 1.3 matt bv %r0(%rp) 65 1.8 skrll and %ret0, %ret1, %ret0 66 1.1 fredette EXIT(__vfork14) 67
Indexes created Mon Sep 22 05:09:51 GMT 2025