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! crt1.s for Solaris 2, x86 ! Copyright (C) 1993, 1998 Free Software Foundation, Inc. ! Written By Fred Fish, Nov 1992 ! ! This file is free software; you can redistribute it and/or modify it ! under the terms of the GNU General Public License as published by the ! Free Software Foundation; either version 2, or (at your option) any ! later version. ! ! In addition to the permissions in the GNU 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 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.) ! ! This file 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 ! General Public License for more details. ! ! You should have received a copy of the GNU General Public License ! along with this program; see the file COPYING. If not, write to ! the Free Software Foundation, 51 Franklin Street, Fifth Floor, ! Boston, MA 02110-1301, USA. ! ! As a special exception, if you link this library with files ! compiled with GCC to produce an executable, this does not cause ! the resulting executable to be covered by the GNU General Public License. ! This exception does not however invalidate any other reasons why ! the executable file might be covered by the GNU General Public License. ! ! This file takes control of the process from the kernel, as specified ! in section 3 of the System V Application Binary Interface, Intel386 ! Processor Supplement. It has been constructed from information obtained ! from the ABI, information obtained from single stepping existing ! Solaris executables through their startup code with gdb, and from ! information obtained by single stepping executables on other i386 SVR4 ! implementations. This file is the first thing linked into any executable. .file "crt1.s" .ident "GNU C crt1.s" .weak _cleanup .weak _DYNAMIC .text ! Start creating the initial frame by pushing a NULL value for the return ! address of the initial frame, and mark the end of the stack frame chain ! (the innermost stack frame) with a NULL value, per page 3-32 of the ABI. ! Initialize the first stack frame pointer in %ebp (the contents of which ! are unspecified at process initialization). .globl _start _start: pushl $0x0 pushl $0x0 movl %esp,%ebp ! As specified per page 3-32 of the ABI, %edx contains a function ! pointer that should be registered with atexit(), for proper ! shared object termination. Just push it onto the stack for now ! to preserve it. We want to register _cleanup() first. pushl %edx ! Check to see if there is an _cleanup() function linked in, and if ! so, register it with atexit() as the last thing to be run by ! atexit(). movl $_cleanup,%eax testl %eax,%eax je .L1 pushl $_cleanup call atexit addl $0x4,%esp .L1: ! Now check to see if we have an _DYNAMIC table, and if so then ! we need to register the function pointer previously in %edx, but ! now conveniently saved on the stack as the argument to pass to ! atexit(). movl $_DYNAMIC,%eax testl %eax,%eax je .L2 call atexit .L2: ! Register _fini() with atexit(). We will take care of calling _init() ! directly. pushl $_fini call atexit ! Compute the address of the environment vector on the stack and load ! it into the global variable _environ. Currently argc is at 8 off ! the frame pointer. Fetch the argument count into %eax, scale by the ! size of each arg (4 bytes) and compute the address of the environment ! vector which is 16 bytes (the two zero words we pushed, plus argc, ! plus the null word terminating the arg vector) further up the stack, ! off the frame pointer (whew!). movl 8(%ebp),%eax leal 16(%ebp,%eax,4),%edx movl %edx,_environ ! Push the environment vector pointer, the argument vector pointer, ! and the argument count on to the stack to set up the arguments ! for _init(), _fpstart(), and main(). Note that the environment ! vector pointer and the arg count were previously loaded into ! %edx and %eax respectively. The only new value we need to compute ! is the argument vector pointer, which is at a fixed address off ! the initial frame pointer. ! ! Make sure the stack is properly aligned. ! andl $0xfffffff0,%esp subl $4,%esp pushl %edx leal 12(%ebp),%edx pushl %edx pushl %eax ! Call _init(argc, argv, environ), _fpstart(argc, argv, environ), and ! main(argc, argv, environ). call _init call __fpstart call main ! Pop the argc, argv, and environ arguments off the stack, push the ! value returned from main(), and call exit(). addl $12,%esp pushl %eax call exit ! An inline equivalent of _exit, as specified in Figure 3-26 of the ABI. pushl $0x0 movl $0x1,%eax lcall $7,$0 ! If all else fails, just try a halt! hlt .type _start,@function .size _start,.-_start ! A dummy profiling support routine for non-profiling executables, ! in case we link in some objects that have been compiled for profiling. .weak _mcount _mcount: ret .type _mcount,@function .size _mcount,.-_mcount