x86_64/sys/getpid.s

   1 /*
   2  * Copyright (c) 1999-2003 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 /*
  24  * Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved
  25  */
  26 #include <SYS.h>
  27
  28         .data
  29         .private_extern __current_pid
  30 __current_pid:
  31         .long 0
  32
  33 /*
  34  * If __current_pid is > 0, return it, else make syscall.
  35  * If __current_pid is 0, cache result of syscall.
  36  */
  37 TEXT
  38 LEAF(_getpid, 0)
  39         movl    __current_pid(%rip), %eax
  40         testl   %eax, %eax
  41         jle             1f
  42         ret
  43 1:
  44         UNIX_SYSCALL_NONAME(getpid, 0)
  45         movl            %eax, %edx
  46         xorl            %eax, %eax
  47         leaq            __current_pid(%rip), %rcx
  48         lock
  49         cmpxchgl        %edx, (%rcx)
  50         movl            %edx, %eax
  51         ret