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 2004 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27/*
28 * This crt1.o module is provided as the bare minimum required to build a
29 * 64-bit progile executable with gcc -pg.  It is installed in /usr/lib/amd64
30 * where it will be picked up by gcc, along with crti.o and crtn.o
31 */
32
33	.ident	"%Z%%M%	%I%	%E% SMI"
34
35	.file	"gcrt1.s"
36
37	.globl	_start
38	.globl	_etext
39
40/* global entities defined elsewhere but used here */
41	.globl	main
42	.globl	__fpstart
43	.globl	_init
44	.globl	_fini
45	.globl	exit
46	.globl	_exit
47	.globl	monstartup
48	.weak	_mcleanup
49	.weak	_DYNAMIC
50
51	.section	.data
52
53	.weak	environ
54	.set	environ,_environ
55	.globl	_environ
56	.type	_environ,@object
57	.size	_environ,8
58	.align	8
59_environ:
60	.8byte	0x0
61
62	.globl	___Argv
63	.type	___Argv,@object
64	.size	___Argv,8
65	.align	8
66___Argv:
67	.8byte	0x0
68
69	.section	.text
70	.align	8
71
72/*
73 *   The SVR4/i386 ABI (pages 3-29) says that when the entry
74 *   point runs registers' %rbp, %rsp, %rdx values are specified
75 *   the following:
76 *
77 *	%rbp The content of this register is unspecified at
78 *		process initialization time, but the user code should mark
79 *		the deepest stack frame by setting the frame pointer to zero.
80 *		No other frame's %ebp should have a zero value.
81 *
82 *	%rsp Performing its usual job, the stack pointer holds the address
83 *	of the bottom of the stack, which is guaranteed to be
84 *	quadword aligned.
85 *
86 *		The stack contains the arguments and environment:
87 *        ...
88 *        envp[0]		(16+(8*argc))(%rsp)
89 *        NULL			(8+(8*argc))(%rsp)
90 *        ...
91 *        argv[0]		8(%rsp)
92 *        argc			0(%rsp)
93 *
94 *	%rdx In a conforming program, this register contains a function
95 *		pointer that the application should register with atexit(BA_OS).
96 *		This function is used for shared object termination code
97 *		[see Dynamic Linking in Chapter 5 of the System V ABI].
98 *
99 */
100
101	.type	_start,@function
102_start:
103/*
104 * Allocate a NULL return address and a NULL previous %rbp as if
105 * there was a genuine call to _start.
106 */
107	pushq	$0
108	pushq	$0
109	movq	%rsp,%rbp		/* The first stack frame */
110
111/*
112 * The stack now is
113 *
114 *        envp[0]		(32+(8*argc))(%rsp)      - (A)
115 *        NULL			(24+(8*argc))(%rsp)
116 *        ...
117 *        argv[0]		24(%rbp)		 - (B)
118 *        argc			16(%rbp)
119 *	  0			8(%rbp)
120 *	  0			0(%rbp)
121 */
122
123/*
124 * Check to see if there is an _mcleanup() function linked in, and if so,
125 * register it with atexit() as the last thing to be run by exit().
126 */
127	movq	%rdx,%r12		/* save rt_do_exit for later atexit */
128
129	movq	$_mcleanup,%rdi
130	testq	%rdi,%rdi
131	jz	1f
132	call	atexit
1331:
134
135	movq	$_DYNAMIC,%rax
136	testq	%rax,%rax
137	jz	1f
138	movq	%r12,%rdi		/* register rt_do_exit */
139	call	atexit
1401:
141
142	movq	$_fini,%rdi
143	call	atexit
144
145/* start profiling */
146	pushq	%rbp
147	movq	%rsp,%rbp
148	movq	$_start,%rdi
149	movq	$_etext,%rsi
150	call	monstartup
151	popq	%rbp
152
153/*
154 * Calculate the location of the envp array by adding the size of
155 * the argv array to the start of the argv array.
156 */
157	movq	16(%rbp),%rax		/* argc */
158	movq	_environ, %rcx
159	testq	%rcx, %rcx		/* check if _environ==0 */
160	jne	1f
161	leaq	32(%rbp,%rax,8),%rcx	/* (A) */
162	movq	%rcx,_environ		/* copy to _environ */
1631:
164
165/*
166 * Force stack alignment - below here there must have been an even
167 * number of un-popped pushq instructions whenever a call is reached
168 */
169	andq	$-16,%rsp
170	pushq	%rdx
171	leaq	24(%rbp),%rdx		/* argv (B) */
172	movq	%rdx,___Argv
173	pushq	%rcx
174	pushq	%rdx
175	pushq	%rax
176	call	__fpstart
177	call	_init
178	popq	%rdi
179	popq	%rsi
180	popq	%rdx
181	popq	%rcx
182	call	main			/* main(argc,argv,envp) */
183	pushq	%rax
184	pushq	%rax
185	movq	%rax,%rdi		/* and call exit */
186	call	exit
187	popq	%rdi
188	popq	%rdi
189	call	_exit		/* if user redefined exit, call _exit */
190	hlt
191	.size	_start, .-_start
192