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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2010 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
.file "vforkx.s"
#include "SYS.h"
#include <assym.h>
/*
* pid = vforkx(flags);
* syscall trap: forksys(2, flags)
*
* pid = vfork();
* syscall trap: forksys(2, 0)
*
* From the syscall:
* %edx == 0 in parent process, %edx = 1 in child process.
* %eax == pid of child in parent, %eax == pid of parent in child.
*
* The child gets a zero return value.
* The parent gets the pid of the child.
*/
/*
* The child of vfork() will execute in the parent's address space,
* thereby changing the stack before the parent runs again.
* Therefore we have to be careful how we return from vfork().
* Pity the poor debugger developer who has to deal with this kludge.
*
* We block all blockable signals while performing the vfork() system call
* trap. This enables us to set curthread->ul_vfork safely, so that we
* don't end up in a signal handler with curthread->ul_vfork set wrong.
*/
ENTRY_NP(vforkx)
movl 4(%esp), %eax /* flags */
jmp 0f
ENTRY_NP(vfork)
xorl %eax, %eax /* flags = 0 */
0:
popl %ecx /* save return %eip in %ecx */
pushl %eax /* flags */
pushl $MASKSET3 /* block all signals */
pushl $MASKSET2
pushl $MASKSET1
pushl $MASKSET0
pushl $SIG_SETMASK
pushl %ecx
__SYSCALLINT(lwp_sigmask)
addl $24, %esp
pushl $2
pushl %ecx
__SYSCALLINT(forksys) /* vforkx(flags) */
jae 1f
/* reconstruct stack before jumping to __cerror */
addl $12, %esp
pushl %ecx
pushl %eax /* save the vfork() error number */
pushl %gs:UL_SIGMASK+12 /* reinstate signals */
pushl %gs:UL_SIGMASK+8
pushl %gs:UL_SIGMASK+4
pushl %gs:UL_SIGMASK
pushl $SIG_SETMASK
pushl %ecx
__SYSCALLINT(lwp_sigmask)
addl $24, %esp
popl %eax /* restore the vfork() error number */
jmp __cerror
1:
addl $12, %esp
/*
* To determine if we are (still) a child of vfork(), the child
* increments curthread->ul_vfork by one and the parent decrements
* it by one. If the result is zero, then we are not a child of
* vfork(), else we are. We do this to deal with the case of
* a vfork() child calling vfork().
*/
cmpl $0, %edx
jne 2f
movl %gs:UL_VFORK, %edx
cmpl $0, %edx /* don't let it go negative */
je 3f
subl $1, %edx /* curthread->ul_vfork--; */
jmp 3f
2:
xorl %eax, %eax /* zero the return value in the child */
movl %gs:UL_VFORK, %edx
addl $1, %edx /* curthread->ul_vfork++; */
3:
movl %edx, %gs:UL_VFORK
/*
* Clear the schedctl interface in both parent and child.
* (The child might have modified the parent.)
*/
xorl %edx, %edx
movl %edx, %gs:UL_SCHEDCTL
movl %edx, %gs:UL_SCHEDCTL_CALLED
pushl %eax /* save the vfork() return value */
pushl %gs:UL_SIGMASK+12 /* reinstate signals */
pushl %gs:UL_SIGMASK+8
pushl %gs:UL_SIGMASK+4
pushl %gs:UL_SIGMASK
pushl $SIG_SETMASK
pushl %ecx
__SYSCALLINT(lwp_sigmask)
addl $24, %esp
popl %eax /* restore the vfork() return value */
jmp *%ecx /* jump back to the caller */
SET_SIZE(vfork)
SET_SIZE(vforkx)
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