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      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. Neither the name of the University nor the names of its contributors
     14  *    may be used to endorse or promote products derived from this software
     15  *    without specific prior written permission.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     27  * SUCH DAMAGE.
     28  */
     29 
     30 #include "SYS.h"
     31 
     32 #if defined(SYSLIBC_SCCS) && !defined(lint)
     33 	/* .asciz "@(#)Ovfork.s	8.1 (Berkeley) 6/4/93" */
     34 RCSID("$NetBSD: __vfork14.S,v 1.7 2011/11/21 16:17:48 chs Exp $")
     35 #endif /* SYSLIBC_SCCS and not lint */
     36 
     37 /*
     38  * @(#)vfork.s	4.1 (Berkeley) 12/21/80
     39  * C library -- vfork
     40  */
     41 
     42 /*
     43  * pid = vfork();
     44  *
     45  * %r1 == 0 in parent process, %r1 == 1 in child process.
     46  * %r0 == pid of child in parent, %r0 == pid of parent in child.
     47  *
     48  * trickery here, due to keith sklower, uses ret to clear the stack,
     49  * and then returns with a jump indirect, since only one person can return
     50  * with a ret off this stack... we do the ret before we vfork!
     51  */
     52 
     53 ENTRY(__vfork14, 0)
     54 	movl	16(%fp),%r0	# save return address before we smash it
     55 	movab	here,16(%fp)
     56 	ret
     57 here:
     58 	movl	%r0,%r2
     59 	chmk	$ SYS___vfork14
     60 	bcs	err		# if failed, set errno and return -1
     61 	/* this next trick is Chris Torek's fault */
     62 	mnegl	%r1,%r1		# %r1 = 0xffffffff if child, 0 if parent
     63 	bicl2	%r1,%r0		# %r0 &= ~%r1, i.e., 0 if child, else unchanged
     64 	jmp	(%r2)
     65 
     66 err:
     67 #ifdef _REENTRANT
     68 	pushr	$0x5
     69 	calls	$0,_C_LABEL(__errno)
     70 	movl	(%sp)+,(%r0)
     71 	mnegl	$1,%r0
     72 	rsb
     73 #else
     74 	movl	%r0,_C_LABEL(errno)
     75 	mnegl	$1,%r0
     76 	jmp	(%r2)
     77 #endif
     78 END(__vfork14)
     79