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 .file "vforkx.s" 28 29#include "SYS.h" 30#include <assym.h> 31 32/* 33 * pid = vforkx(flags); 34 * syscall trap: forksys(2, flags) 35 * 36 * pid = vfork(); 37 * syscall trap: forksys(2, 0) 38 * 39 * From the syscall: 40 * %edx == 0 in parent process, %edx = 1 in child process. 41 * %eax == pid of child in parent, %eax == pid of parent in child. 42 * 43 * The child gets a zero return value. 44 * The parent gets the pid of the child. 45 */ 46 47/* 48 * The child of vfork() will execute in the parent's address space, 49 * thereby changing the stack before the parent runs again. 50 * Therefore we have to be careful how we return from vfork(). 51 * Pity the poor debugger developer who has to deal with this kludge. 52 * 53 * We block all blockable signals while performing the vfork() system call 54 * trap. This enables us to set curthread->ul_vfork safely, so that we 55 * don't end up in a signal handler with curthread->ul_vfork set wrong. 56 */ 57 58 ENTRY_NP(vforkx) 59 movl 4(%esp), %eax /* flags */ 60 jmp 0f 61 ENTRY_NP(vfork) 62 xorl %eax, %eax /* flags = 0 */ 630: 64 popl %ecx /* save return %eip in %ecx */ 65 pushl %eax /* flags */ 66 pushl $MASKSET1 /* block all signals */ 67 pushl $MASKSET0 68 pushl $SIG_SETMASK 69 pushl %ecx 70 __SYSCALLINT(lwp_sigmask) 71 addl $16, %esp 72 73 pushl $2 74 pushl %ecx 75 __SYSCALLINT(forksys) /* vforkx(flags) */ 76 jae 1f 77 78 /* reconstruct stack before jumping to __cerror */ 79 addl $12, %esp 80 pushl %ecx 81 pushl %eax /* save the vfork() error number */ 82 83 pushl %gs:UL_SIGMASK+4 /* reinstate signals */ 84 pushl %gs:UL_SIGMASK 85 pushl $SIG_SETMASK 86 pushl %ecx 87 __SYSCALLINT(lwp_sigmask) 88 addl $16, %esp 89 90 popl %eax /* restore the vfork() error number */ 91 jmp __cerror 92 931: 94 addl $12, %esp 95 /* 96 * To determine if we are (still) a child of vfork(), the child 97 * increments curthread->ul_vfork by one and the parent decrements 98 * it by one. If the result is zero, then we are not a child of 99 * vfork(), else we are. We do this to deal with the case of 100 * a vfork() child calling vfork(). 101 */ 102 cmpl $0, %edx 103 jne 2f 104 movl %gs:UL_VFORK, %edx 105 cmpl $0, %edx /* don't let it go negative */ 106 je 3f 107 subl $1, %edx /* curthread->ul_vfork--; */ 108 jmp 3f 1092: 110 xorl %eax, %eax /* zero the return value in the child */ 111 movl %gs:UL_VFORK, %edx 112 addl $1, %edx /* curthread->ul_vfork++; */ 1133: 114 movl %edx, %gs:UL_VFORK 115 /* 116 * Clear the schedctl interface in both parent and child. 117 * (The child might have modified the parent.) 118 */ 119 xorl %edx, %edx 120 movl %edx, %gs:UL_SCHEDCTL 121 movl %edx, %gs:UL_SCHEDCTL_CALLED 122 pushl %eax /* save the vfork() return value */ 123 124 pushl %gs:UL_SIGMASK+4 /* reinstate signals */ 125 pushl %gs:UL_SIGMASK 126 pushl $SIG_SETMASK 127 pushl %ecx 128 __SYSCALLINT(lwp_sigmask) 129 addl $16, %esp 130 131 popl %eax /* restore the vfork() return value */ 132 jmp *%ecx /* jump back to the caller */ 133 SET_SIZE(vfork) 134 SET_SIZE(vforkx) 135