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 2006 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/asm_linkage.h> 32 33 ANSI_PRAGMA_WEAK(vforkx,function) 34 ANSI_PRAGMA_WEAK(vfork,function) 35 36#include "SYS.h" 37#include <assym.h> 38 39/* 40 * pid = vforkx(flags); 41 * syscall trap: forksys(2, flags) 42 * 43 * pid = vfork(); 44 * syscall trap: forksys(2, 0) 45 * 46 * From the syscall: 47 * %edx == 0 in parent process, %edx = 1 in child process. 48 * %eax == pid of child in parent, %eax == pid of parent in child. 49 * 50 * The child gets a zero return value. 51 * The parent gets the pid of the child. 52 */ 53 54/* 55 * The child of vfork() will execute in the parent's address space, 56 * thereby changing the stack before the parent runs again. 57 * Therefore we have to be careful how we return from vfork(). 58 * Pity the poor debugger developer who has to deal with this kludge. 59 * 60 * We block all blockable signals while performing the vfork() system call 61 * trap. This enables us to set curthread->ul_vfork safely, so that we 62 * don't end up in a signal handler with curthread->ul_vfork set wrong. 63 */ 64 65 ENTRY_NP(vforkx) 66 movq %rdi, %r8 /* flags */ 67 jmp 0f 68 ENTRY_NP(vfork) 69 xorq %r8, %r8 /* flags = 0 */ 700: 71 popq %r9 /* save return %rip in %r9 */ 72 movl $MASKSET1, %edx /* block all signals */ 73 movl $MASKSET0, %esi 74 movl $SIG_SETMASK, %edi 75 __SYSCALL(lwp_sigmask) 76 77 movq %r8, %rsi /* flags */ 78 movl $2, %edi 79 __SYSCALL(forksys) /* vforkx(flags) */ 80 jae 1f 81 82 /* reconstruct stack before jumping to __cerror */ 83 pushq %r9 84 movq %rax, %r8 /* save the vfork() error number */ 85 86 movl %fs:UL_SIGMASK+4, %edx /* reinstate signals */ 87 movl %fs:UL_SIGMASK, %esi 88 movl $SIG_SETMASK, %edi 89 __SYSCALL(lwp_sigmask) 90 91 movq %r8, %rax /* restore the vfork() error number */ 92 jmp __cerror 93 941: 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 %fs: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 %fs:UL_VFORK, %edx 112 addl $1, %edx /* curthread->ul_vfork++; */ 1133: 114 movl %edx, %fs:UL_VFORK 115 /* 116 * Clear the schedctl interface in both parent and child. 117 * (The child might have modified the parent.) 118 */ 119 xorq %rdx, %rdx 120 movq %rdx, %fs:UL_SCHEDCTL 121 movq %rdx, %fs:UL_SCHEDCTL_CALLED 122 movq %rax, %r8 /* save the vfork() return value */ 123 124 movl %fs:UL_SIGMASK+4, %edx /* reinstate signals */ 125 movl %fs:UL_SIGMASK, %esi 126 movl $SIG_SETMASK, %edi 127 __SYSCALL(lwp_sigmask) 128 129 movq %r8, %rax /* restore the vfork() return value */ 130 jmp *%r9 /* jump back to the caller */ 131 SET_SIZE(vfork) 132 SET_SIZE(vforkx) 133