1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
|
/* Copyright (C) 1991, 1992 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
/* Based on the code from GNU libc, but hacked up by John Beppu and Erik Andersen */
/*
When we enter this piece of code, the program stack looks like this:
argc argument counter (integer)
argv[0] program name (pointer)
argv[1...N] program args (pointers)
argv[argc-1] end of args (integer)
NULL
env[0...N] environment variables (pointers)
NULL
*/
#include <features.h>
.text
.align 4
.global _start
.type _start,%function
#if defined L_crt0 || ! defined __UCLIBC_CTOR_DTOR__
.type __uClibc_main,%function
#else
.weak _init
.weak _fini
.type __uClibc_start_main,%function
#endif
/* Stick in a dummy reference to main(), so that if an application
* is linking when the main() function is in a static library (.a)
* we can be sure that main() actually gets linked in */
.type main,%function
_start:
/* locate the start of the environment variables */
popl %ecx /* Store argc into %ecx */
movl %esp,%ebx /* Store argv into ebx */
movl %esp,%eax /* Store argv into eax as well*/
movl %ecx,%edx /* Stick argc into %edx so we can do some math in a sec */
leal 4(%eax,%edx,4),%eax
/* [ register layout ]
sizeof(char*) == 4
%ecx = argc ; 0(esp)
%ebx = argv ; 4(esp)
%eax = env ; argv + (argc * 4) + 4
*/
/* Set up an invalid (NULL return address, NULL frame pointer)
callers stack frame so anybody unrolling the stack knows where
to stop */
xorl %ebp,%ebp /* NULL */
pushl %ebp /* callers %cs */
pushl %ebp /* callers %eip (return address) */
pushl %ebp /* callers %ebp (frame pointer) */
movl %esp,%ebp /* mark callers stack frame as invalid */
#if (defined L_crt1 || defined L_gcrt1 ) && defined __UCLIBC_CTOR_DTOR__
/* Push .init and .fini arguments to __uClibc_start_main() on the stack */
pushl $_fini
pushl $_init
/* Push envp, argc, and argc arguments to __uClibc_start_main() on the stack */
pushl %eax /* Environment pointer */
pushl %ebx /* Argument pointer */
pushl %ecx /* And the argument count */
/* Ok, now run uClibc's main() -- shouldn't return */
call __uClibc_start_main
#else
/* Push envp, argc, and argc arguments to __uClibc_start_main() on the stack */
pushl %eax /* Environment pointer */
pushl %ebx /* Argument pointer */
pushl %ecx /* And the argument count */
call __uClibc_main
#endif
/* Crash if somehow `exit' returns anyways. */
hlt
.size _start,.-_start
#if defined L_gcrt1 && defined __UCLIBC_PROFILING__
# include "./gmon-start.S"
#endif
|
