ppc/sys/fork.s

   1 /*
   2  * Copyright (c) 1999-2004 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 /* Copyright (c) 1992 NeXT Computer, Inc.  All rights reserved.
  24  *
  25  *      File:   libc/ppc/sys/fork.s
  26  *
  27  * HISTORY
  28  * 18-Nov-92  Ben Fathi (benf@next.com)
  29  *      Created from M88K sources
  30  *
  31  * 11-Jan-92  Peter King (king@next.com)
  32  *      Created from M68K sources
  33  */
  34
  35 /* We use mode-independent "g" opcodes such as "srgi".  These expand
  36  * into word operations when targeting __ppc__, and into doubleword
  37  * operations when targeting __ppc64__.
  38  */
  39 #include <architecture/ppc/mode_independent_asm.h>
  40
  41 #include "SYS.h"
  42
  43
  44 MI_ENTRY_POINT(_fork)
  45     MI_PUSH_STACK_FRAME
  46
  47     MI_CALL_EXTERNAL(__cthread_fork_prepare)
  48
  49 #if defined(__DYNAMIC__)
  50     .cstring
  51 LC1:
  52         .ascii  "__dyld_fork_prepare\0"
  53     .text
  54         .align 2
  55         mflr    r0
  56         bcl     20,31,1f
  57 1:      mflr    r3
  58         mtlr    r0
  59         addis   r3,r3,ha16(LC1-1b)
  60         addi    r3,r3,lo16(LC1-1b)
  61         addi    r4,r1,SF_LOCAL1
  62         bl      __dyld_func_lookup
  63         lg      r3,SF_LOCAL1(r1)
  64         mtspr   ctr,r3
  65         bctrl
  66 #endif
  67
  68         li      r0,SYS_fork
  69         sc                      // do the fork
  70         b       Lbotch                  // error return
  71
  72         cmpwi   r4,0            // parent (r4==0) or child (r4==1) ?
  73         beq     Lparent         // parent, since r4==0
  74
  75
  76 /* Here if we are the child.  */
  77
  78 #if defined(__DYNAMIC__)
  79     .cstring
  80 LC3:
  81         .ascii  "__dyld_fork_child\0"
  82     .text
  83         .align 2
  84         mflr    r0
  85         bcl     20,31,1f
  86 1:      mflr    r3
  87         mtlr    r0
  88         addis   r3,r3,ha16(LC3-1b)
  89         addi    r3,r3,lo16(LC3-1b)
  90         addi    r4,r1,SF_LOCAL1
  91         bl      __dyld_func_lookup
  92         lg      r3,SF_LOCAL1(r1)
  93         mtspr   ctr,r3
  94         bctrl
  95 #endif
  96
  97     li      r9,0
  98     MI_GET_ADDRESS(r8,__current_pid)
  99     stw     r9,0(r8)            // clear cached pid in child
 100
 101         MI_CALL_EXTERNAL(__cthread_fork_child)
 102
 103 #if defined(__DYNAMIC__)
 104     .cstring
 105 LC4:
 106         .ascii  "__dyld_fork_child_final\0"
 107     .text
 108         .align 2
 109         mflr    r0
 110         bcl     20,31,1f
 111 1:      mflr    r3
 112         mtlr    r0
 113         addis   r3,r3,ha16(LC4-1b)
 114         addi    r3,r3,lo16(LC4-1b)
 115         addi    r4,r1,SF_LOCAL1
 116         bl      __dyld_func_lookup
 117         lg      r3,SF_LOCAL1(r1)
 118         mtspr   ctr,r3
 119         bctrl
 120 #endif
 121
 122         li      r3,0        // flag for "we are the child"
 123         b       Lreturn
 124
 125
 126 /* Here if we are the parent, with:
 127  *  r3 = child's pid
 128  */
 129 Lparent:
 130         stg     r3,SF_LOCAL2(r1)        // save child pid in stack
 131
 132 #if defined(__DYNAMIC__)
 133         mflr    r0
 134         bcl     20,31,1f
 135 1:      mflr    r3
 136         mtlr    r0
 137         addis   r3,r3,ha16(LC2-1b)
 138         addi    r3,r3,lo16(LC2-1b)
 139         addi    r4,r1,SF_LOCAL1
 140         bl      __dyld_func_lookup
 141         lg      r3,SF_LOCAL1(r1)
 142         mtspr   ctr,r3
 143         bctrl
 144 #endif
 145
 146     b       Lparent_return      // clean up and return child's pid
 147
 148
 149 /* Here if the fork() syscall failed.  We're still the parent.  */
 150
 151 Lbotch:
 152
 153 #if defined(__DYNAMIC__)
 154     .cstring
 155 LC2:
 156         .ascii  "__dyld_fork_parent\0"
 157     .text
 158         .align 2
 159         stg     r3,SF_LOCAL2(r1)        // save error return in stack
 160         mflr    r0
 161         bcl     20,31,1f
 162 1:      mflr    r3
 163         mtlr    r0
 164         addis   r3,r3,ha16(LC2-1b)
 165         addi    r3,r3,lo16(LC2-1b)
 166         addi    r4,r1,SF_LOCAL1
 167         bl      __dyld_func_lookup
 168         lg      r3,SF_LOCAL1(r1)
 169         mtspr   ctr,r3
 170         bctrl
 171         lg      r3,SF_LOCAL2(r1)    // restore error code
 172 #endif
 173
 174         MI_CALL_EXTERNAL(cerror)
 175     li      r3,-1               // get an error return code
 176         stg     r3,SF_LOCAL2(r1)        // save return code in stack
 177
 178         /*
 179          * We use cthread_fork_parent() to clean up after a fork error
 180          * (unlock cthreads and mailloc packages) so the parent
 181          * process can Malloc() after fork() errors without
 182          * deadlocking.
 183          */
 184
 185 Lparent_return:
 186         MI_CALL_EXTERNAL(__cthread_fork_parent)
 187         lg      r3,SF_LOCAL2(r1)    // return -1 on error, child's pid on success
 188
 189 Lreturn:
 190     MI_POP_STACK_FRAME_AND_RETURN
 191