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__vfork14.S revision 1.4 
      1 /*
      2  * Copyright (c) 1983, 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #if defined(SYSLIBC_SCCS) && !defined(lint)
     35 	/* .asciz "@(#)Ovfork.s	8.1 (Berkeley) 6/4/93" */
     36 	.asciz "$NetBSD: __vfork14.S,v 1.4 2002/02/24 01:06:20 matt Exp $"
     37 #endif /* SYSLIBC_SCCS and not lint */
     38 
     39 /*
     40  * @(#)vfork.s	4.1 (Berkeley) 12/21/80
     41  * C library -- vfork
     42  */
     43 
     44 #include "SYS.h"
     45 
     46 /*
     47  * pid = vfork();
     48  *
     49  * %r1 == 0 in parent process, %r1 == 1 in child process.
     50  * %r0 == pid of child in parent, %r0 == pid of parent in child.
     51  *
     52  * trickery here, due to keith sklower, uses ret to clear the stack,
     53  * and then returns with a jump indirect, since only one person can return
     54  * with a ret off this stack... we do the ret before we vfork!
     55  */
     56 
     57 ENTRY(__vfork14, 0)
     58 	movl	16(%fp),%r2	# save return address before we smash it
     59 	movab	here,16(%fp)
     60 	ret
     61 here:
     62 	chmk	$ SYS___vfork14
     63 	bcs	err		# if failed, set errno and return -1
     64 	/* this next trick is Chris Torek's fault */
     65 	mnegl	%r1,%r1		# %r1 = 0xffffffff if child, 0 if parent
     66 	bicl2	%r1,%r0		# %r0 &= ~%r1, i.e., 0 if child, else unchanged
     67 	jmp	(%r2)
     68 
     69 err:
     70 #ifdef _REENTRANT
     71 	pushr	$0x5
     72 	calls	$0,_C_LABEL(__errno)
     73 	movl	(%sp)+,(%r0)
     74 	mnegl	$1,%r0
     75 	rsb
     76 #else
     77 	movl	%r0,_C_LABEL(errno)
     78 	mnegl	$1,%r0
     79 	jmp	(%r2)
     80 #endif
     81