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
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
|
/* Startup code compliant to the ELF Xtensa ABI.
Copyright (C) 2001, 2007 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.
In addition to the permissions in the GNU Lesser General Public
License, the Free Software Foundation gives you unlimited
permission to link the compiled version of this file with other
programs, and to distribute those programs without any restriction
coming from the use of this file. (The GNU Lesser General Public
License restrictions do apply in other respects; for example, they
cover modification of the file, and distribution when not linked
into another program.)
Note that people who make modified versions of this file are not
obligated to grant this special exception for their modified
versions; it is their choice whether to do so. The GNU Lesser
General Public License gives permission to release a modified
version without this exception; this exception also makes it
possible to release a modified version which carries forward this
exception.
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
<http://www.gnu.org/licenses/>. */
#include <features.h>
#if defined(__FDPIC__)
/* This is the canonical entry point, usually the first thing in the text
segment. When the entry point runs, most register values are unspecified,
except for:
a6 Address of .dynamic section
a5 Interpreter map
a4 Executable map
a2 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.
a1 The stack (i.e., a1+16) contains the arguments and environment:
a1+0 argc
a1+4 argv[0]
...
a1+(4*argc) NULL
a1+(4*(argc+1)) envp[0]
...
NULL
*/
.text
.align 4
.literal_position
.global _start
.type _start, @function
_start:
#if defined(__XTENSA_CALL0_ABI__)
.begin no-transform
call0 1f
2:
.end no-transform
.align 4
.literal_position
1:
movi a15, 2b
sub a15, a0, a15
mov a12, a4
mov a13, a5
mov a14, a6
mov a2, a4
movi a3, __ROFIXUP_LIST__
add a3, a3, a15
movi a4, __ROFIXUP_END__
add a4, a4, a15
movi a0, __self_reloc
add a0, a0, a15
callx0 a0
mov a11, a2
movi a2, main@GOTOFFFUNCDESC
add a2, a2, a11
l32i a3, sp, 0 /* argc */
addi a4, sp, 4 /* argv */
/* a5 is either 0 when static or set by the RTLD to the rtld_fini */
mov a7, a13
/* unused stack_end argument is what used to be argc */
movi a5, _init@GOTOFFFUNCDESC
add a5, a5, a11
movi a6, _fini@GOTOFFFUNCDESC
add a6, a6, a11
movi a0, __uClibc_main@GOTOFFFUNCDESC
add a0, a0, a11
l32i a11, a0, 4
l32i a0, a0, 0
callx0 a0
ill
#else
#error Unsupported Xtensa ABI
#endif
#else /* defined(__FDPIC__) */
#ifndef __UCLIBC_CTOR_DTOR__
.weak _init
.weak _fini
#endif
/* This is the canonical entry point, usually the first thing in the text
segment. When the entry point runs, most register values are unspecified,
except for:
a2 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.
a1 The stack (i.e., a1+16) contains the arguments and environment:
a1+0 argc
a1+4 argv[0]
...
a1+(4*argc) NULL
a1+(4*(argc+1)) envp[0]
...
NULL
Setup parameters accordingly (for a call4). See function prototype
from sysdeps/generic/libc-start.c
a6 = *main
a7 = argc
a8 = ubp_av
a9 = *init
a10 = *fini
a11 = *rtld_fini
[sp+0] = stack_end
*/
.text
.align 4
.literal_position
.global _start
.type _start, @function
_start:
#ifdef L_rcrt1
.begin no-transform
call0 1f
.Lret_addr:
.end no-transform
.align 4
1:
#endif
#if defined(__XTENSA_WINDOWED_ABI__)
#ifdef L_rcrt1
movi a6, .Lret_addr
sub a6, a0, a6
movi a0, 0
movi a4, reloc_static_pie
add a4, a4, a6
callx4 a4
#else
/* Clear a0 to obviously mark the outermost frame. */
movi a0, 0
#endif
/* Load up the user's main function. */
movi a6, main
/* Extract the arguments as encoded on the stack and set up
the arguments for `main': argc, argv. envp will be determined
later in __uClibc_main. */
l32i a7, a1, 0 /* Load the argument count. */
addi a8, a1, 4 /* Compute the argv pointer. */
/* Push address of our own entry points to .fini and .init. */
movi a9, _init
movi a10, _fini
/* Setup the shared library termination function. */
mov a11, a2
/* Provide the highest stack address to the user code (for stacks
which grow downwards). Note that we destroy the stack version
of argc here. */
s32i a1, a1, 0
/* Call the user's main function, and exit with its value.
But let the libc call main. */
movi a4, __uClibc_main
callx4 a4
#elif defined(__XTENSA_CALL0_ABI__)
#ifdef L_rcrt1
mov a12, a2
movi a2, .Lret_addr
sub a2, a0, a2
movi a0, reloc_static_pie
add a0, a0, a2
callx0 a0
mov a7, a12
#else
/* Setup the shared library termination function. */
mov a7, a2
#endif
/* Load up the user's main function. */
movi a2, main
/* Extract the arguments as encoded on the stack and set up
the arguments for `main': argc, argv. envp will be determined
later in __uClibc_main. */
l32i a3, a1, 0 /* Load the argument count. */
addi a4, a1, 4 /* Compute the argv pointer. */
/* Push address of our own entry points to .fini and .init. */
movi a5, _init
movi a6, _fini
/* Provide the highest stack address to the user code (for stacks
which grow downwards). Note that we destroy the stack version
of argc here. */
s32i a1, a1, 0
/* Call the user's main function, and exit with its value.
But let the libc call main. */
movi a0, __uClibc_main
callx0 a0
#else
#error Unsupported Xtensa ABI
#endif
/* Crash if somehow `exit' does return. */
ill
/* Define a symbol for the first piece of initialized data. */
.data
.align 4
.global __data_start
__data_start:
.long 0
.weak data_start
data_start = __data_start
#endif /* defined(__FDPIC__) */
|
