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1 ! crt1.s for Solaris 2, x86
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2
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3 ! Copyright (C) 1993, 1998, 2008, 2009 Free Software Foundation, Inc.
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4 ! Written By Fred Fish, Nov 1992
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5 !
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6 ! This file is free software; you can redistribute it and/or modify it
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7 ! under the terms of the GNU General Public License as published by the
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8 ! Free Software Foundation; either version 3, or (at your option) any
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9 ! later version.
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10 !
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11 ! This file is distributed in the hope that it will be useful, but
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12 ! WITHOUT ANY WARRANTY; without even the implied warranty of
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13 ! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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14 ! General Public License for more details.
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15 !
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16 ! Under Section 7 of GPL version 3, you are granted additional
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17 ! permissions described in the GCC Runtime Library Exception, version
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18 ! 3.1, as published by the Free Software Foundation.
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19 !
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20 ! You should have received a copy of the GNU General Public License and
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21 ! a copy of the GCC Runtime Library Exception along with this program;
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22 ! see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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23 ! <http://www.gnu.org/licenses/>.
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24
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25
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26 ! This file takes control of the process from the kernel, as specified
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27 ! in section 3 of the System V Application Binary Interface, Intel386
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28 ! Processor Supplement. It has been constructed from information obtained
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29 ! from the ABI, information obtained from single stepping existing
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30 ! Solaris executables through their startup code with gdb, and from
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31 ! information obtained by single stepping executables on other i386 SVR4
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32 ! implementations. This file is the first thing linked into any executable.
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33
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34 .ident "GNU C crt1.s"
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35 .weak _cleanup
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36 .weak _DYNAMIC
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37 .text
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38
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39 ! Start creating the initial frame by pushing a NULL value for the return
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40 ! address of the initial frame, and mark the end of the stack frame chain
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41 ! (the innermost stack frame) with a NULL value, per page 3-32 of the ABI.
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42 ! Initialize the first stack frame pointer in %ebp (the contents of which
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43 ! are unspecified at process initialization).
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44
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45 .globl _start
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46 _start:
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47 pushl $0x0
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48 pushl $0x0
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49 movl %esp,%ebp
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50
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51 ! As specified per page 3-32 of the ABI, %edx contains a function
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52 ! pointer that should be registered with atexit(), for proper
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53 ! shared object termination. Just push it onto the stack for now
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54 ! to preserve it. We want to register _cleanup() first.
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55
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56 pushl %edx
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57
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58 ! Check to see if there is an _cleanup() function linked in, and if
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59 ! so, register it with atexit() as the last thing to be run by
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60 ! atexit().
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61
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62 movl $_cleanup,%eax
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63 testl %eax,%eax
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64 je .L1
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65 pushl $_cleanup
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66 call atexit
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67 addl $0x4,%esp
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68 .L1:
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69
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70 ! Now check to see if we have an _DYNAMIC table, and if so then
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71 ! we need to register the function pointer previously in %edx, but
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72 ! now conveniently saved on the stack as the argument to pass to
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73 ! atexit().
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74
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75 movl $_DYNAMIC,%eax
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76 testl %eax,%eax
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77 je .L2
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78 call atexit
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79 .L2:
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80
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81 ! Register _fini() with atexit(). We will take care of calling _init()
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82 ! directly.
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83
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84 pushl $_fini
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85 call atexit
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86
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87 ! Compute the address of the environment vector on the stack and load
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88 ! it into the global variable _environ. Currently argc is at 8 off
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89 ! the frame pointer. Fetch the argument count into %eax, scale by the
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90 ! size of each arg (4 bytes) and compute the address of the environment
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91 ! vector which is 16 bytes (the two zero words we pushed, plus argc,
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92 ! plus the null word terminating the arg vector) further up the stack,
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93 ! off the frame pointer (whew!).
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94
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95 movl 8(%ebp),%eax
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96 leal 16(%ebp,%eax,4),%edx
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97 movl %edx,_environ
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98
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99 ! Push the environment vector pointer, the argument vector pointer,
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100 ! and the argument count on to the stack to set up the arguments
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101 ! for _init(), _fpstart(), and main(). Note that the environment
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102 ! vector pointer and the arg count were previously loaded into
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103 ! %edx and %eax respectively. The only new value we need to compute
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104 ! is the argument vector pointer, which is at a fixed address off
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105 ! the initial frame pointer.
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106
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107 !
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108 ! Make sure the stack is properly aligned.
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109 !
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110 andl $0xfffffff0,%esp
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111 subl $4,%esp
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112
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113 pushl %edx
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114 leal 12(%ebp),%edx
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115 pushl %edx
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116 pushl %eax
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117
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118 ! Call _init(argc, argv, environ), _fpstart(argc, argv, environ), and
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119 ! main(argc, argv, environ).
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120
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121 call _init
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122 call __fpstart
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123 call main
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124
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125 ! Pop the argc, argv, and environ arguments off the stack, push the
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126 ! value returned from main(), and call exit().
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127
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128 addl $12,%esp
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129 pushl %eax
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130 call exit
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131
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132 ! An inline equivalent of _exit, as specified in Figure 3-26 of the ABI.
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133
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134 pushl $0x0
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135 movl $0x1,%eax
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136 lcall $7,$0
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137
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138 ! If all else fails, just try a halt!
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139
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140 hlt
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141 .type _start,@function
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142 .size _start,.-_start
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143
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144 ! A dummy profiling support routine for non-profiling executables,
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145 ! in case we link in some objects that have been compiled for profiling.
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146
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147 .weak _mcount
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148 _mcount:
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149 ret
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150 .type _mcount,@function
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151 .size _mcount,.-_mcount
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