i386/sys/vfork.s

   1 /*
   2  * Copyright (c) 1999-2003 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved
  27  */
  28 #include "SYS.h"
  29
  30 #if defined(__DYNAMIC__)
  31 #define GET_CURRENT_PID PICIFY(__current_pid)
  32
  33         NON_LAZY_STUB(__current_pid)
  34 #define __current_pid   (%edx)
  35 #else
  36 #define GET_CURRENT_PID
  37 #endif
  38
  39 /*
  40  * If __current_pid >= 0, we want to put a -1 in there
  41  * otherwise we just decrement it
  42  */
  43
  44 LEAF(_vfork, 0)
  45         GET_CURRENT_PID
  46         movl            __current_pid, %eax
  47 0:
  48         xorl            %ecx, %ecx
  49         testl           %eax, %eax
  50         cmovs           %eax, %ecx
  51         decl            %ecx
  52         lock
  53         cmpxchgl        %ecx, __current_pid
  54         jne             0b
  55         popl            %ecx
  56         movl            $(SYS_vfork), %eax      // code for vfork -> eax
  57         UNIX_SYSCALL_TRAP                       // do the system call
  58         jnb             L1                      // jump if CF==0
  59         GET_CURRENT_PID
  60         lock
  61         incl            __current_pid
  62         pushl           %ecx
  63         BRANCH_EXTERN(cerror)
  64
  65 L1:
  66         testl           %edx, %edx              // CF=OF=0,  ZF set if zero result
  67         jz              L2                      // parent, since r1 == 0 in parent, 1 in child
  68         xorl            %eax, %eax              // zero eax
  69         jmp             *%ecx
  70
  71 L2:
  72         GET_CURRENT_PID
  73         lock
  74         incl            __current_pid
  75         jmp             *%ecx