xref: /illumos-gate/usr/src/cmd/sgs/rtld/i386/boot.S (revision 6c19a8c5028aaa5491c62aaf7daf8f9919ec09d3)
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, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22/*
23 *	Copyright (c) 1988 AT&T
24 *	  All Rights Reserved
25 *
26 *
27 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
28 * Use is subject to license terms.
29 */
30
31/*
32 * Bootstrap routine for run-time linker.
33 * We get control from exec which has loaded our text and
34 * data into the process' address space and created the process
35 * stack.
36 *
37 * On entry, the process stack looks like this:
38 *
39 *	#			# <- %esp
40 *	#_______________________#  high addresses
41 *	#	strings		#
42 *	#_______________________#
43 *	#	0 word		#
44 *	#_______________________#
45 *	#	Auxiliary	#
46 *	#	entries		#
47 *	#	...		#
48 *	#	(size varies)	#
49 *	#_______________________#
50 *	#	0 word		#
51 *	#_______________________#
52 *	#	Environment	#
53 *	#	pointers	#
54 *	#	...		#
55 *	#	(one word each)	#
56 *	#_______________________#
57 *	#	0 word		#
58 *	#_______________________#
59 *	#	Argument	# low addresses
60 *	#	pointers	#
61 *	#	Argc words	#
62 *	#_______________________#
63 *	#	argc		#
64 *	#_______________________# <- %ebp
65 *
66 *
67 * We must calculate the address at which ld.so was loaded,
68 * find the addr of the dynamic section of ld.so, of argv[0], and  of
69 * the process' environment pointers - and pass the thing to _setup
70 * to handle.  We then call _rtld - on return we jump to the entry
71 * point for the executable.
72 */
73
74#if	defined(lint)
75
76extern	unsigned long	_setup();
77extern	void		atexit_fini();
78void
79main()
80{
81	(void) _setup();
82	atexit_fini();
83}
84
85#else
86
87#include	<link.h>
88
89	.file	"boot.s"
90	.text
91	.globl	_rt_boot
92	.globl	_setup
93	.globl	_GLOBAL_OFFSET_TABLE_
94	.type	_rt_boot,@function
95	.align	4
96
97	/ init is called from the _init symbol in the CRT, however .init_array
98	/ are called "naturally" from call_init.  Because of that, we need the
99	/ stack aligned here so that initializers called via _array sections may
100	/ safely use SIMD instructions.
101_rt_alias:
102	jmp	.get_ip			/ in case we were invoked from libc.so
103_rt_boot:
104	movl	%esp,%ebp		/ save for referencing args
105	subl	$EB_MAX_SIZE32,%esp	/ make room for a max sized boot vector
106	andl	$-16,%esp
107	subl	$8,%esp
108	movl	%esp,%esi		/ use esi as a pointer to &eb[0]
109	movl	$EB_ARGV,0(%esi)	/ set up tag for argv
110	leal	4(%ebp),%eax		/ get address of argv
111	movl	%eax,4(%esi)		/ put after tag
112	movl	$EB_ENVP,8(%esi)	/ set up tag for envp
113	movl	(%ebp),%eax		/ get # of args
114	addl	$2,%eax			/ one for the zero & one for argc
115	leal	(%ebp,%eax,4),%edi	/ now points past args & @ envp
116	movl	%edi,12(%esi)		/ set envp
117.L0:	addl	$4,%edi			/ next
118	cmpl	$0,-4(%edi)		/ search for 0 at end of env
119	jne	.L0
120	movl	$EB_AUXV,16(%esi)	/ set up tag for auxv
121	movl	%edi,20(%esi)		/ point to auxv
122	movl	$EB_NULL,24(%esi)	/ set up NULL tag
123.get_ip:
124	call	.L1			/ only way to get IP into a register
125.L1:
126	popl	%ebx			/ pop the IP we just "pushed"
127	addl	$_GLOBAL_OFFSET_TABLE_+[.-.L1],%ebx
128	pushl	(%ebx)			/ address of dynamic structure
129	pushl	%esi			/ push &eb[0]
130
131	call	_setup@PLT		/ _setup(&eb[0], _DYNAMIC)
132	movl	%ebp,%esp		/ release stack frame
133
134	movl	atexit_fini@GOT(%ebx), %edx
135	jmp	*%eax			/ transfer control to the executable
136	.size	_rt_boot,.-_rt_boot
137
138#endif
139