1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22/*
23 * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
24 */
25
26#include <sys/asm_linkage.h>
27
28#if defined(lint)
29
30void
31_start(void)
32{
33}
34
35#else	/* lint */
36	/*
37	 * Initial entry point for the brand emulation library.
38	 *
39	 * This platform specific assembly entry point exists just to invoke
40	 * the common brand library startup routine.  That routine expects to
41	 * be called with the following arguments:
42	 *	brand_init(int argc, char *argv[], char *envp[])
43	 *
44	 * There are no arguments explicitly passed to this entry point,
45	 * routine, but we do know how our initial stack has been setup by
46	 * the kernel.  The stack format is documented in:
47	 *	usr/src/cmd/sgs/rtld/amd64/boot.s
48	 *
49	 * So this routine will troll through the stack to setup the argument
50	 * values for the common brand library startup routine and then invoke
51	 * it.  This routine is modeled after the default crt1.s`_start()
52	 * routines.
53	 */
54	ENTRY_NP(_start)
55
56	/* Make stack traces look pretty, build a fake stack frame. */
57	pushq	$0			/ Build a stack frame. retpc = NULL
58	pushq	$0			/ fp = NULL
59	movq	%rsp, %rbp		/ first stack frame
60
61	/*
62	 * Calculate the location of the envp array by adding the size of
63	 * the argv array to the start of the argv array.
64	 */
65	movq	16(%rbp), %rdi		/ argc in %rax (1st param)
66	leaq	24(%rbp), %rsi		/ &argv[0] in %rbx (2nd param)
67	leaq	32(%rbp,%rdi,8), %rdx	/ envp in %rcx (3rd param)
68	call	brand_init
69
70	/*NOTREACHED*/
71	SET_SIZE(_start)
72#endif	/* lint */
73