1! crt1.s for Solaris 2, x86 2 3! Copyright (C) 1993, 1998 Free Software Foundation, Inc. 4! Written By Fred Fish, Nov 1992 5! 6! This file is free software; you can redistribute it and/or modify it 7! under the terms of the GNU General Public License as published by the 8! Free Software Foundation; either version 2, or (at your option) any 9! later version. 10! 11! In addition to the permissions in the GNU General Public License, the 12! Free Software Foundation gives you unlimited permission to link the 13! compiled version of this file with other programs, and to distribute 14! those programs without any restriction coming from the use of this 15! file. (The General Public License restrictions do apply in other 16! respects; for example, they cover modification of the file, and 17! distribution when not linked into another program.) 18! 19! This file is distributed in the hope that it will be useful, but 20! WITHOUT ANY WARRANTY; without even the implied warranty of 21! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 22! General Public License for more details. 23! 24! You should have received a copy of the GNU General Public License 25! along with this program; see the file COPYING. If not, write to 26! the Free Software Foundation, 51 Franklin Street, Fifth Floor, 27! Boston, MA 02110-1301, USA. 28! 29! As a special exception, if you link this library with files 30! compiled with GCC to produce an executable, this does not cause 31! the resulting executable to be covered by the GNU General Public License. 32! This exception does not however invalidate any other reasons why 33! the executable file might be covered by the GNU General Public License. 34! 35 36! This file takes control of the process from the kernel, as specified 37! in section 3 of the System V Application Binary Interface, Intel386 38! Processor Supplement. It has been constructed from information obtained 39! from the ABI, information obtained from single stepping existing 40! Solaris executables through their startup code with gdb, and from 41! information obtained by single stepping executables on other i386 SVR4 42! implementations. This file is the first thing linked into any executable. 43 44 .file "crt1.s" 45 .ident "GNU C crt1.s" 46 .weak _cleanup 47 .weak _DYNAMIC 48 .text 49 50! Start creating the initial frame by pushing a NULL value for the return 51! address of the initial frame, and mark the end of the stack frame chain 52! (the innermost stack frame) with a NULL value, per page 3-32 of the ABI. 53! Initialize the first stack frame pointer in %ebp (the contents of which 54! are unspecified at process initialization). 55 56 .globl _start 57_start: 58 pushl $0x0 59 pushl $0x0 60 movl %esp,%ebp 61 62! As specified per page 3-32 of the ABI, %edx contains a function 63! pointer that should be registered with atexit(), for proper 64! shared object termination. Just push it onto the stack for now 65! to preserve it. We want to register _cleanup() first. 66 67 pushl %edx 68 69! Check to see if there is an _cleanup() function linked in, and if 70! so, register it with atexit() as the last thing to be run by 71! atexit(). 72 73 movl $_cleanup,%eax 74 testl %eax,%eax 75 je .L1 76 pushl $_cleanup 77 call atexit 78 addl $0x4,%esp 79.L1: 80 81! Now check to see if we have an _DYNAMIC table, and if so then 82! we need to register the function pointer previously in %edx, but 83! now conveniently saved on the stack as the argument to pass to 84! atexit(). 85 86 movl $_DYNAMIC,%eax 87 testl %eax,%eax 88 je .L2 89 call atexit 90.L2: 91 92! Register _fini() with atexit(). We will take care of calling _init() 93! directly. 94 95 pushl $_fini 96 call atexit 97 98! Compute the address of the environment vector on the stack and load 99! it into the global variable _environ. Currently argc is at 8 off 100! the frame pointer. Fetch the argument count into %eax, scale by the 101! size of each arg (4 bytes) and compute the address of the environment 102! vector which is 16 bytes (the two zero words we pushed, plus argc, 103! plus the null word terminating the arg vector) further up the stack, 104! off the frame pointer (whew!). 105 106 movl 8(%ebp),%eax 107 leal 16(%ebp,%eax,4),%edx 108 movl %edx,_environ 109 110! Push the environment vector pointer, the argument vector pointer, 111! and the argument count on to the stack to set up the arguments 112! for _init(), _fpstart(), and main(). Note that the environment 113! vector pointer and the arg count were previously loaded into 114! %edx and %eax respectively. The only new value we need to compute 115! is the argument vector pointer, which is at a fixed address off 116! the initial frame pointer. 117 118! 119! Make sure the stack is properly aligned. 120! 121 andl $0xfffffff0,%esp 122 subl $4,%esp 123 124 pushl %edx 125 leal 12(%ebp),%edx 126 pushl %edx 127 pushl %eax 128 129! Call _init(argc, argv, environ), _fpstart(argc, argv, environ), and 130! main(argc, argv, environ). 131 132 call _init 133 call __fpstart 134 call main 135 136! Pop the argc, argv, and environ arguments off the stack, push the 137! value returned from main(), and call exit(). 138 139 addl $12,%esp 140 pushl %eax 141 call exit 142 143! An inline equivalent of _exit, as specified in Figure 3-26 of the ABI. 144 145 pushl $0x0 146 movl $0x1,%eax 147 lcall $7,$0 148 149! If all else fails, just try a halt! 150 151 hlt 152 .type _start,@function 153 .size _start,.-_start 154 155! A dummy profiling support routine for non-profiling executables, 156! in case we link in some objects that have been compiled for profiling. 157 158 .weak _mcount 159_mcount: 160 ret 161 .type _mcount,@function 162 .size _mcount,.-_mcount 163