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1 /*
2  * Copyright (C) 2013 The Android Open Source Project
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *  * Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  *  * Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in
12  *    the documentation and/or other materials provided with the
13  *    distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19  * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #include <stddef.h>
30 #include <stdint.h>
31 #include <sys/cdefs.h>
32 
33 extern int main(int argc, char** argv, char** env);
34 
35 typedef struct
36 {
37     void (**preinit_array)(void);
38     void (**init_array)(void);
39     void (**fini_array)(void);
40     void (**ctor_list)(void);
41     void (**dtor_list)(void);
42 } structors_array_t;
43 
44 __attribute__ ((section (".preinit_array")))
45 void (*__PREINIT_ARRAY__)(void) = (void (*)(void)) -1;
46 
47 __attribute__ ((section (".init_array")))
48 void (*__INIT_ARRAY__)(void) = (void (*)(void)) -1;
49 
50 __attribute__ ((section (".fini_array")))
51 void (*__FINI_ARRAY__)(void) = (void (*)(void)) -1;
52 
53 __attribute__ ((section (".ctors")))
54 void (*__CTOR_LIST__)(void) = (void (*)(void)) -1;
55 
56 __attribute__ ((section (".dtors")))
57 void (*__DTOR_LIST__)(void) = (void (*)(void)) -1;
58 
do_mips_start(void * raw_args)59 __LIBC_HIDDEN__  void do_mips_start(void *raw_args) {
60   structors_array_t array;
61   array.preinit_array = &__PREINIT_ARRAY__;
62   array.init_array = &__INIT_ARRAY__;
63   array.fini_array = &__FINI_ARRAY__;
64   array.ctor_list = &__CTOR_LIST__;
65   array.dtor_list = &__DTOR_LIST__;
66 
67   __libc_init(raw_args, NULL, &main, &array);
68 }
69 
70 /*
71  * This function prepares the return address with a branch-and-link
72  * instruction (bal) and then uses a .cpload to compute the Global
73  * Offset Table (GOT) pointer ($gp). The $gp is then used to load
74  * the address of _do_start() into $t9 just before calling it.
75  * Terminating the stack with a NULL return address.
76  */
77 __asm__ (
78 "       .set push                   \n"
79 "                                   \n"
80 "       .text                       \n"
81 "       .align  4                   \n"
82 "       .type __start,@function     \n"
83 "       .globl __start              \n"
84 "       .globl  _start              \n"
85 "                                   \n"
86 "       .ent    __start             \n"
87 "__start:                           \n"
88 " _start:                           \n"
89 "       .frame   $sp,32,$ra         \n"
90 "       .mask   0x80000000,-4       \n"
91 "                                   \n"
92 "       .set noreorder              \n"
93 "       bal     1f                  \n"
94 "       nop                         \n"
95 "1:                                 \n"
96 "       .cpload $ra                 \n"
97 "       .set reorder                \n"
98 "                                   \n"
99 "       move    $a0, $sp            \n"
100 "       addiu   $sp, $sp, (-32)     \n"
101 "       sw      $0, 28($sp)         \n"
102 "       la      $t9, do_mips_start  \n"
103 "       jalr    $t9                 \n"
104 "                                   \n"
105 "2:     b       2b                  \n"
106 "       .end    __start             \n"
107 "                                   \n"
108 "       .set pop                    \n"
109 );
110 
111 #include "__dso_handle.h"
112 #include "atexit.h"
113