sysdeps/unix/sysv/linux/sh/vfork.S

   1 /* Copyright (C) 2004-2015 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <sysdep.h>
  19 #define _ERRNO_H        1
  20 #include <bits/errno.h>
  21 #include <tcb-offsets.h>
  22
  23 /* Clone the calling process, but without copying the whole address space.
  24    The calling process is suspended until the new process exits or is
  25    replaced by a call to `execve'.  Return -1 for errors, 0 to the new process,
  26    and the process ID of the new process to the old process.  */
  27
  28 ENTRY (__libc_vfork)
  29         /* Save the PID value.  */
  30         stc     gbr, r2
  31         mov.w   .L2, r0
  32         mov.l   @(r0,r2), r4
  33         neg     r4, r1
  34         tst     r1, r1
  35         bf      1f
  36         mov     #1, r1
  37         rotr    r1
  38 1:
  39         mov.l   r1, @(r0,r2)
  40
  41         mov.w   .L1, r3
  42         trapa   #0x10
  43         mov     r0, r1
  44
  45         /* Restore the old PID value in the parent.  */
  46         tst     r0, r0
  47         bt.s    2f
  48          stc    gbr, r2
  49         mov.w   .L2, r0
  50         mov.l   r4, @(r0,r2)
  51         mov     r1, r0
  52 2:
  53         mov     #-12, r2
  54         shad    r2, r1
  55         not     r1, r1                  // r1=0 means r0 = -1 to -4095
  56         tst     r1, r1                  // i.e. error in linux
  57         bf      .Lpseudo_end
  58         SYSCALL_ERROR_HANDLER
  59 .Lpseudo_end:
  60         rts
  61          nop
  62 .L1:
  63         .word   __NR_vfork
  64 .L2:
  65         .word   PID - TLS_PRE_TCB_SIZE
  66         .align  2
  67 PSEUDO_END (__libc_vfork)
  68
  69 #if IS_IN (libc)
  70 weak_alias (__libc_vfork, vfork)
  71 strong_alias (__libc_vfork, __vfork)
  72 libc_hidden_def (__vfork)
  73 #endif