1/* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22/* 23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27#pragma ident "%Z%%M% %I% %E% SMI" 28 29 .file "%M%" 30 31#include "SYS.h" 32#include <assym.h> 33 34/* 35 * pid = vforkx(flags); 36 * syscall trap: forksys(2, flags) 37 * 38 * pid = vfork(); 39 * syscall trap: forksys(2, 0) 40 * 41 * From the syscall: 42 * %edx == 0 in parent process, %edx = 1 in child process. 43 * %eax == pid of child in parent, %eax == pid of parent in child. 44 * 45 * The child gets a zero return value. 46 * The parent gets the pid of the child. 47 */ 48 49/* 50 * The child of vfork() will execute in the parent's address space, 51 * thereby changing the stack before the parent runs again. 52 * Therefore we have to be careful how we return from vfork(). 53 * Pity the poor debugger developer who has to deal with this kludge. 54 * 55 * We block all blockable signals while performing the vfork() system call 56 * trap. This enables us to set curthread->ul_vfork safely, so that we 57 * don't end up in a signal handler with curthread->ul_vfork set wrong. 58 */ 59 60 ENTRY_NP(vforkx) 61 movl 4(%esp), %eax /* flags */ 62 jmp 0f 63 ENTRY_NP(vfork) 64 xorl %eax, %eax /* flags = 0 */ 650: 66 popl %ecx /* save return %eip in %ecx */ 67 pushl %eax /* flags */ 68 pushl $MASKSET1 /* block all signals */ 69 pushl $MASKSET0 70 pushl $SIG_SETMASK 71 pushl %ecx 72 __SYSCALLINT(lwp_sigmask) 73 addl $16, %esp 74 75 pushl $2 76 pushl %ecx 77 __SYSCALLINT(forksys) /* vforkx(flags) */ 78 jae 1f 79 80 /* reconstruct stack before jumping to __cerror */ 81 addl $12, %esp 82 pushl %ecx 83 pushl %eax /* save the vfork() error number */ 84 85 pushl %gs:UL_SIGMASK+4 /* reinstate signals */ 86 pushl %gs:UL_SIGMASK 87 pushl $SIG_SETMASK 88 pushl %ecx 89 __SYSCALLINT(lwp_sigmask) 90 addl $16, %esp 91 92 popl %eax /* restore the vfork() error number */ 93 jmp __cerror 94 951: 96 addl $12, %esp 97 /* 98 * To determine if we are (still) a child of vfork(), the child 99 * increments curthread->ul_vfork by one and the parent decrements 100 * it by one. If the result is zero, then we are not a child of 101 * vfork(), else we are. We do this to deal with the case of 102 * a vfork() child calling vfork(). 103 */ 104 cmpl $0, %edx 105 jne 2f 106 movl %gs:UL_VFORK, %edx 107 cmpl $0, %edx /* don't let it go negative */ 108 je 3f 109 subl $1, %edx /* curthread->ul_vfork--; */ 110 jmp 3f 1112: 112 xorl %eax, %eax /* zero the return value in the child */ 113 movl %gs:UL_VFORK, %edx 114 addl $1, %edx /* curthread->ul_vfork++; */ 1153: 116 movl %edx, %gs:UL_VFORK 117 /* 118 * Clear the schedctl interface in both parent and child. 119 * (The child might have modified the parent.) 120 */ 121 xorl %edx, %edx 122 movl %edx, %gs:UL_SCHEDCTL 123 movl %edx, %gs:UL_SCHEDCTL_CALLED 124 pushl %eax /* save the vfork() return value */ 125 126 pushl %gs:UL_SIGMASK+4 /* reinstate signals */ 127 pushl %gs:UL_SIGMASK 128 pushl $SIG_SETMASK 129 pushl %ecx 130 __SYSCALLINT(lwp_sigmask) 131 addl $16, %esp 132 133 popl %eax /* restore the vfork() return value */ 134 jmp *%ecx /* jump back to the caller */ 135 SET_SIZE(vfork) 136 SET_SIZE(vforkx) 137