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
107
108
109
110
111
112
113
|
/* Copyright (C) 1995-2020 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 Lesser General Public License as
published by the Free Software Foundation; either version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library. If not, see
<https://www.gnu.org/licenses/>. */
#include <sysdep.h>
/* This is the canonical entry point, usually the first thing in the text
segment.
Note that the code in the .init section has already been run.
This includes _init and _libc_init
At this entry point, most registers' values are unspecified, except:
x0/w0 Contains a function pointer to be registered with `atexit'.
This is how the dynamic linker arranges to have DT_FINI
functions called for shared libraries that have been loaded
before this code runs.
sp The stack contains the arguments and environment:
0(sp) argc
8(sp) argv[0]
...
(8*argc)(sp) NULL
(8*(argc+1))(sp) envp[0]
...
NULL
*/
.text
.globl _start
.type _start,#function
_start:
BTI_C
/* Create an initial frame with 0 LR and FP */
mov x29, #0
mov x30, #0
/* Setup rtld_fini in argument register */
mov x5, x0
/* Load argc and a pointer to argv */
ldr PTR_REG (1), [sp, #0]
add x2, sp, #PTR_SIZE
/* Setup stack limit in argument register */
mov x6, sp
#ifdef PIC
# ifdef SHARED
adrp x0, :got:main
ldr PTR_REG (0), [x0, #:got_lo12:main]
adrp x3, :got:__libc_csu_init
ldr PTR_REG (3), [x3, #:got_lo12:__libc_csu_init]
adrp x4, :got:__libc_csu_fini
ldr PTR_REG (4), [x4, #:got_lo12:__libc_csu_fini]
# else
adrp x0, __wrap_main
add x0, x0, :lo12:__wrap_main
adrp x3, __libc_csu_init
add x3, x3, :lo12:__libc_csu_init
adrp x4, __libc_csu_fini
add x4, x4, :lo12:__libc_csu_fini
# endif
#else
/* Set up the other arguments in registers */
MOVL (0, main)
MOVL (3, __libc_csu_init)
MOVL (4, __libc_csu_fini)
#endif
/* __libc_start_main (main, argc, argv, init, fini, rtld_fini,
stack_end) */
/* Let the libc call main and exit with its return code. */
bl __libc_start_main
/* should never get here....*/
bl abort
#if defined PIC && !defined SHARED
/* When main is not defined in the executable but in a shared library
then a wrapper is needed in crt1.o of the static-pie enabled libc,
because crt1.o and rcrt1.o share code and the later must avoid the
use of GOT relocations before __libc_start_main is called. */
__wrap_main:
b main
#endif
/* Define a symbol for the first piece of initialized data. */
.data
.globl __data_start
__data_start:
.long 0
.weak data_start
data_start = __data_start
|
