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__clone.S revision 1.5 
      1 /*	$NetBSD: __clone.S,v 1.5 2003/02/08 00:28:25 cgd Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2001 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Jason R. Thorpe.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the NetBSD
     21  *	Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 #include <sys/errno.h>
     40 
     41 #include "SYS.h"
     42 
     43 #ifdef WEAK_ALIAS
     44 WEAK_ALIAS(clone, __clone)
     45 #endif
     46 
     47 /*
     48  * int __clone(int (*fn)(void *), void *stack, int flags, void *arg);
     49  */
     50 LEAF(__clone)
     51 	PIC_PROLOGUE(__clone, t9)
     52 
     53 	/*
     54 	 * Sanity checks: func and stack may not be NULL.
     55 	 */
     56 	li	v0, EINVAL
     57 	beq	a0, zero, 8f
     58 	beq	a1, zero, 8f
     59 
     60 	/*
     61 	 * We need to be able to get at the func and arg arguments
     62 	 * in the child.  Luckily, we have a convenient place to
     63 	 * do this: the child's stack.
     64 	 */
     65 	subu	a1, a1, (2 * SZREG)
     66 	REG_S	a0, 0(a1)
     67 	REG_S	a3, SZREG(a1)
     68 
     69 	/*
     70 	 * The system call expects (flags, stack).
     71 	 */
     72 	move	a0, a2
     73 	SYSTRAP(__clone)
     74 	bne	a3, zero, 8f
     75 
     76 	bne	v1, zero, 9f	# v1 (rv[1]) == 0, parent, child pid in v0
     77 
     78 	j	ra		# parent return
     79 
     80 8:	PIC_CALL(__cerror, t9)
     81 	/* NOTREACHED */
     82 
     83 9:	/*
     84 	 * Child: Fetch the function and argument from the new stack,
     85 	 * and create a frame so that the child can be safely called.
     86 	 *
     87 	 * There are already register slots on the stack from above.
     88 	 * We take 4 register slots more.  The lower 4 acommodate o32
     89 	 * argument save area.  The next higher is used to save GP (if
     90 	 * ABICALLS).  The highest is unused.
     91 	 */
     92 	REG_L	t9, 0(sp)
     93 	REG_L	a0, SZREG(sp)
     94 	subu	sp, sp, (4 * SZREG)
     95 
     96 #ifdef __ABICALLS__
     97 	.cprestore (4 * SZREG)
     98 #endif
     99 
    100 	/* Call the clone's entry point. */
    101 	jal	t9
    102 
    103 	/* Pass the return value to _exit(). */
    104 	move	a0, v0
    105 	PIC_CALL(_exit, t9)
    106 
    107 	/* NOTREACHED */
    108 END(__clone)
    109