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__clone.S revision 1.7.8.2 
      1 /*	$NetBSD: __clone.S,v 1.7.8.2 2008/04/28 20:22:57 martin 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  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/errno.h>
     33 
     34 #include "SYS.h"
     35 
     36 #ifdef WEAK_ALIAS
     37 WEAK_ALIAS(clone, __clone)
     38 #endif
     39 
     40 /*
     41  * int __clone(int (*fn)(void *), void *stack, int flags, void *arg);
     42  */
     43 LEAF(__clone)
     44 	PIC_PROLOGUE(__clone, t9)
     45 
     46 	/*
     47 	 * Sanity checks: func and stack may not be NULL.
     48 	 */
     49 	li	v0, EINVAL
     50 	beq	a0, zero, 8f
     51 	beq	a1, zero, 8f
     52 
     53 	/*
     54 	 * We need to be able to get at the func and arg arguments
     55 	 * in the child.  Luckily, we have a convenient place to
     56 	 * do this: the child's stack.
     57 	 */
     58 	subu	a1, a1, (2 * SZREG)
     59 	REG_S	a0, 0(a1)
     60 	REG_S	a3, SZREG(a1)
     61 
     62 	/*
     63 	 * The system call expects (flags, stack).
     64 	 */
     65 	move	a0, a2
     66 	SYSTRAP(__clone)
     67 	bne	a3, zero, 8f
     68 
     69 	bne	v1, zero, 9f	# v1 (rv[1]) == 0, parent, child pid in v0
     70 
     71 	j	ra		# parent return
     72 
     73 8:	PIC_CALL(__cerror, t9)
     74 	/* NOTREACHED */
     75 
     76 9:	/*
     77 	 * Child: Fetch the function and argument from the new stack,
     78 	 * and create a frame so that the child can be safely called.
     79 	 *
     80 	 * There are already register slots on the stack from above.
     81 	 * We take 4 register slots more.  The lower 4 accommodate o32
     82 	 * argument save area.  The next higher is used to save GP (if
     83 	 * ABICALLS).  The highest is unused.
     84 	 */
     85 	REG_L	t9, 0(sp)
     86 	REG_L	a0, SZREG(sp)
     87 	subu	sp, sp, (4 * SZREG)
     88 
     89 #ifdef __ABICALLS__
     90 	.cprestore (4 * SZREG)
     91 #endif
     92 
     93 	/* Call the clone's entry point. */
     94 	jal	t9
     95 
     96 	/* Pass the return value to _exit(). */
     97 	move	a0, v0
     98 	PIC_CALL(_exit, t9)
     99 
    100 	/* NOTREACHED */
    101 END(__clone)
    102