diff options
Diffstat (limited to 'sysdeps/unix/bsd/i386')
| -rw-r--r-- | sysdeps/unix/bsd/i386/vfork.S | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/sysdeps/unix/bsd/i386/vfork.S b/sysdeps/unix/bsd/i386/vfork.S new file mode 100644 index 0000000000..af7f907bd6 --- /dev/null +++ b/sysdeps/unix/bsd/i386/vfork.S @@ -0,0 +1,39 @@ +/* Copyright (C) 1993, 1994, 1995 Free Software Foundation, Inc. +This file is part of the GNU C Library. + +The GNU C Library is free software; you can redistribute it and/or +modify it under the terms of the GNU Library General Public License as +published by the Free Software Foundation; either version 2 of the +License, or (at your option) any later version. + +The GNU C Library is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +Library General Public License for more details. + +You should have received a copy of the GNU Library General Public +License along with the GNU C Library; see the file COPYING.LIB. If +not, write to the Free Software Foundation, Inc., 675 Mass Ave, +Cambridge, MA 02139, USA. */ + +#include <sysdep.h> + +/* Since vfork shares the address space between the parent and child, + we must take care to avoid the child unwinding the stack frame and + clobbering it for the parent. */ + +.text +ENTRY (__vfork) + popl scratch /* Save the return PC in a register. */ + DO_CALL (vfork, 0) /* Do the system call. */ + pushl scratch /* Put the return PC back on the stack. */ + jb syscall_error /* Branch if error. */ + /* R1 is now 0 for the parent and 1 for the child. Decrement it to + make it -1 (all bits set) for the parent, and 0 (no bits set) + for the child. Then AND it with R0, so the parent gets + R0&-1==R0, and the child gets R0&0==0. */ + decl r1 + andl r1, r0 + ret + +weak_alias (__vfork, vfork) |