1/*        $NetBSD: __clone.S,v 1.8 2009/12/14 01:07:42 matt 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#if defined(SYSLIBC_SCCS) && !defined(lint)
37          RCSID("$NetBSD: __clone.S,v 1.8 2009/12/14 01:07:42 matt Exp $");
38#endif /* SYSLIBC_SCCS and not lint */
39
40#ifdef WEAK_ALIAS
41WEAK_ALIAS(clone, __clone)
42#endif
43
44/*
45 * int __clone(int (*fn)(void *), void *stack, int flags, void *arg);
46 */
47LEAF(__clone)
48          PIC_PROLOGUE(__clone)
49
50          /*
51           * Sanity checks: func and stack may not be NULL.
52           */
53          li                  v0, EINVAL
54          beq                 a0, zero, 8f
55          beq                 a1, zero, 8f
56
57          /*
58           * We need to be able to get at the func and arg arguments
59           * in the child.  Luckily, we have a convenient place to
60           * do this: the child's stack.
61           */
62          PTR_SUBU  a1, a1, CALLFRAME_SIZ
63          REG_S               a0, 0(a1)
64          REG_S               a3, SZREG(a1)
65
66          /*
67           * The system call expects (flags, stack).
68           */
69          move                a0, a2
70          SYSTRAP(__clone)
71          bne                 a3, zero, 8f
72
73          bne                 v1, zero, 9f        # v1 (rv[1]) == 0, parent, child pid in v0
74
75          PIC_RETURN()                            # parent return
76
778:        PIC_TAILCALL(__cerror)
78          /* NOTREACHED */
79
809:        /*
81           * Child: Fetch the function and argument from the new stack and create
82           a frame so that the child can be safely called.
83           *
84           * There are already register slots on the stack from above.
85           * They already include the o32 argument save area.  The
86           * highest is unused.  a1 should equal sp now.
87           */
88
89          REG_L               t9, 0(sp)
90          REG_L               a0, SZREG(sp)
91
92          REG_S               zero, CALLFRAME_RA(sp)        /* make sure stack frame ends */
93
94          /* Call the clone's entry point. */
95          SAVE_GP(CALLFRAME_GP)
96          jal                 t9
97
98          /* Pass the return value to _exit. */
99          move                a0, v0
100          PIC_TAILCALL(_exit)
101
102          /* NOTREACHED */
103END(__clone)
104