/*      $NetBSD: __clone.S,v 1.3 2008/04/28 20:22:55 martin Exp $       */

/*-
 * Copyright (c) 2001 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/errno.h>

#include "SYS.h"

#ifdef WEAK_ALIAS
WEAK_ALIAS(clone, __clone)
#endif

/*
 * int __clone(int (*fn)(void *), void *stack, int flags, void *arg);
 */
LEAF(__clone, 4)
        br      pv, 1f
1:      LDGP(pv)
        
        /*
         * Sanity checks: func and stack may not be NULL.
         */
        beq     a0, 9f
        beq     a1, 9f

        /*
         * We need to be able to get at the func and arg arguments
         * in the child.  Luckily, we have a convenient place to
         * do this; the child's stack.
         */
        subq    a1, 16, a1
        stq     a0, 0(a1)
        stq     a3, 8(a1)

        /*
         * The system call expects (flags, stack).
         */
        mov     a2, a0
        CALLSYS_ERROR(__clone)

        beq     a4, 8f          /* a4 (rv[1]) == 0, parent, child pid in v0 */

        /*
         * Fetch the function and argument from the new stack, and
         * pop it back.
         */
        ldq     pv, 0(sp)
        ldq     a0, 8(sp)
        addq    sp, 16, sp

        /* Call the clone's entry point. */
        CALL((pv))

        /* Pass return value to _exit(). */
        mov     v0, a0
        CALL(_exit)

        /* NOTREACHED */

8:      RET

9:      ldiq    v0, EINVAL
        jmp     zero, __cerror
        END(__clone)