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 movq %rdi, %r8 /* flags */ 62 jmp 0f 63 ENTRY_NP(vfork) 64 xorq %r8, %r8 /* flags = 0 */ 650: 66 popq %r9 /* save return %rip in %r9 */ 67 movl $MASKSET1, %edx /* block all signals */ 68 movl $MASKSET0, %esi 69 movl $SIG_SETMASK, %edi 70 __SYSCALL(lwp_sigmask) 71 72 movq %r8, %rsi /* flags */ 73 movl $2, %edi 74 __SYSCALL(forksys) /* vforkx(flags) */ 75 jae 1f 76 77 /* reconstruct stack before jumping to __cerror */ 78 pushq %r9 79 movq %rax, %r8 /* save the vfork() error number */ 80 81 movl %fs:UL_SIGMASK+4, %edx /* reinstate signals */ 82 movl %fs:UL_SIGMASK, %esi 83 movl $SIG_SETMASK, %edi 84 __SYSCALL(lwp_sigmask) 85 86 movq %r8, %rax /* restore the vfork() error number */ 87 jmp __cerror 88 891: 90 /* 91 * To determine if we are (still) a child of vfork(), the child 92 * increments curthread->ul_vfork by one and the parent decrements 93 * it by one. If the result is zero, then we are not a child of 94 * vfork(), else we are. We do this to deal with the case of 95 * a vfork() child calling vfork(). 96 */ 97 cmpl $0, %edx 98 jne 2f 99 movl %fs:UL_VFORK, %edx 100 cmpl $0, %edx /* don't let it go negative */ 101 je 3f 102 subl $1, %edx /* curthread->ul_vfork--; */ 103 jmp 3f 1042: 105 xorl %eax, %eax /* zero the return value in the child */ 106 movl %fs:UL_VFORK, %edx 107 addl $1, %edx /* curthread->ul_vfork++; */ 1083: 109 movl %edx, %fs:UL_VFORK 110 /* 111 * Clear the schedctl interface in both parent and child. 112 * (The child might have modified the parent.) 113 */ 114 xorq %rdx, %rdx 115 movq %rdx, %fs:UL_SCHEDCTL 116 movq %rdx, %fs:UL_SCHEDCTL_CALLED 117 movq %rax, %r8 /* save the vfork() return value */ 118 119 movl %fs:UL_SIGMASK+4, %edx /* reinstate signals */ 120 movl %fs:UL_SIGMASK, %esi 121 movl $SIG_SETMASK, %edi 122 __SYSCALL(lwp_sigmask) 123 124 movq %r8, %rax /* restore the vfork() return value */ 125 jmp *%r9 /* jump back to the caller */ 126 SET_SIZE(vfork) 127 SET_SIZE(vforkx) 128