libsyscall/custom/__vfork.s

   1 /*
   2  * Copyright (c) 1999-2007 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_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. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /* Copyright (c) 1998 Apple Computer, Inc.  All rights reserved.
  29  *
  30  *      File:   libc/ppc/sys/vfork.s
  31  *
  32  * HISTORY
  33  * 23-Jun-1998  Umesh Vaishampayan (umeshv@apple.com)
  34  *      Created from fork.s
  35  *
  36  */
  37
  38 #include "SYS.h"
  39
  40 #if defined(__i386__)
  41
  42 #if defined(__DYNAMIC__)
  43 #define GET_CURRENT_PID PICIFY(__current_pid)
  44
  45         NON_LAZY_STUB(__current_pid)
  46 #define __current_pid   (%edx)
  47 #else
  48 #define GET_CURRENT_PID
  49 #endif
  50
  51 /*
  52  * If __current_pid >= 0, we want to put a -1 in there
  53  * otherwise we just decrement it
  54  */
  55
  56 LEAF(___vfork, 0)
  57         GET_CURRENT_PID
  58         movl            __current_pid, %eax
  59 0:
  60         xorl            %ecx, %ecx
  61         testl           %eax, %eax
  62         cmovs           %eax, %ecx
  63         decl            %ecx
  64         lock
  65         cmpxchgl        %ecx, __current_pid
  66         jne             0b
  67         popl            %ecx
  68         movl            $(SYS_vfork), %eax      // code for vfork -> eax
  69         UNIX_SYSCALL_TRAP                       // do the system call
  70         jnb             L1                      // jump if CF==0
  71         GET_CURRENT_PID
  72         lock
  73         incl            __current_pid
  74         pushl           %ecx
  75         BRANCH_EXTERN(tramp_cerror)
  76
  77 L1:
  78         testl           %edx, %edx              // CF=OF=0,  ZF set if zero result
  79         jz              L2                      // parent, since r1 == 0 in parent, 1 in child
  80         xorl            %eax, %eax              // zero eax
  81         jmp             *%ecx
  82
  83 L2:
  84         GET_CURRENT_PID
  85         lock
  86         incl            __current_pid
  87         jmp             *%ecx
  88
  89 #elif defined(__x86_64__)
  90
  91 /*
  92  * If __current_pid >= 0, we want to put a -1 in there
  93  * otherwise we just decrement it
  94  */
  95
  96 LEAF(___vfork, 0)
  97         movq            __current_pid@GOTPCREL(%rip), %rax
  98         movl            (%rax), %eax
  99 0:
 100         xorl            %ecx, %ecx
 101         testl           %eax, %eax
 102         cmovs           %eax, %ecx
 103         subl            $1, %ecx
 104         movq            __current_pid@GOTPCREL(%rip), %rdx
 105         lock
 106         cmpxchgl        %ecx, (%rdx)
 107         jne             0b
 108         popq            %rdi                    // return address in %rdi
 109         movq            $ SYSCALL_CONSTRUCT_UNIX(SYS_vfork), %rax       // code for vfork -> rax
 110         UNIX_SYSCALL_TRAP                       // do the system call
 111         jnb             L1                      // jump if CF==0
 112         pushq           %rdi                    // put return address back on stack for cerror
 113         movq            __current_pid@GOTPCREL(%rip), %rcx
 114         lock
 115         addq            $1, (%rcx)
 116         movq            %rax, %rdi
 117         BRANCH_EXTERN(_cerror)
 118
 119 L1:
 120         testl           %edx, %edx              // CF=OF=0,  ZF set if zero result
 121         jz              L2                      // parent, since r1 == 0 in parent, 1 in child
 122         xorq            %rax, %rax              // zero rax
 123         jmp             *%rdi
 124
 125 L2:
 126         movq            __current_pid@GOTPCREL(%rip), %rdx
 127         lock
 128         addq            $1, (%rdx)
 129         jmp             *%rdi
 130
 131 #else
 132 #error Unsupported architecture
 133 #endif