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+/* Copyright (C) 1991, 1992 Free Software Foundation, Inc.
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+This file is part of the GNU C Library.
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+
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+The GNU C Library is free software; you can redistribute it and/or
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+modify it under the terms of the GNU Library General Public License as
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+published by the Free Software Foundation; either version 2 of the
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+License, or (at your option) any later version.
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+
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+The GNU C Library is distributed in the hope that it will be useful,
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+but WITHOUT ANY WARRANTY; without even the implied warranty of
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+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+Library General Public License for more details.
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+
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+You should have received a copy of the GNU Library General Public
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+License along with the GNU C Library; see the file COPYING.LIB. If
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+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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+Cambridge, MA 02139, USA. */
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+
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+
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+/* If you don't know what is going on here, check out
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+ http://linuxassembly.org/startup.html
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+ For a description of the stack layout.
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+ -John Beppu, and Erik Andersen
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+*/
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+
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+.global __environ
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+.global __errno
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+.global _start
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+.global exit
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+.global main
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+.global __stdio_close_all
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+.global _void_void_null_func
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+.global _start_exit
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+
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+.text
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+_start:
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+ /* First locate the start of the environment variables */
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+ popl %ecx /* Store argc into %ecx */
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+ movl %esp,%ebx /* Store argv into ebx */
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+ movl %esp,%eax /* Store argv into eax as well*/
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+ movl %ecx,%edx /* Stick argc into %edx so we can do some math in a sec */
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+ leal 4(%eax,%edx,4),%eax
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+
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+ /* [ register layout ]
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+
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+ sizeof(char*) == 4
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+ %ecx = argc ; 0(esp)
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+ %ebx = argv ; 4(esp)
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+ %eax = env ; argv + (argc * 4) + 4
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+ */
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+
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+
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+ /* Set up an invalid (NULL return address, NULL frame pointer)
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+ callers stack frame so anybody unrolling the stack knows where
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+ to stop */
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+ xorl %ebp,%ebp /* NULL */
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+ pushl %ebp /* callers %cs */
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+ pushl %ebp /* callers %eip (return address) */
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+ pushl %ebp /* callers %ebp (frame pointer) */
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+ movl %esp,%ebp /* mark callers stack frame as invalid */
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+
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+ /* Now set the environment, argc, and argv where the app can get to them */
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+ pushl %eax /* Environment pointer */
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+ pushl %ebx /* Argument pointer */
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+ pushl %ecx /* And the argument count */
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+
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+ /* Make sure we are not using iBCS2 personality. (i.e. force linux). */
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+ movl $136,%eax
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+ sub %ebx,%ebx
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+ int $0x80
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+
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+ /* set up __environ */
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+ movl 8(%esp),%eax
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+ movl %eax,__environ
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+
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+ /* Tell libc to initialize anything it needs to do */
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+ call __libc_init
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+ /* call __malloc_init */
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+ call __init_stdio
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+
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+ /* Ok, now run main() */
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+ call main
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+ pushl %eax
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+ call exit
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+
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+ /* Just in case _exit fails... We use int $0x80 for __exit(). */
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+ popl %ebx
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+ .align 4,0x90
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+_start_exit:
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+ movl $1,%eax
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+ int $0x80
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+ jmp _start_exit
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+ .align 4,0x90
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+_void_void_null_func:
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+ ret
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+
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+.weak __libc_init
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+__libc_init = _void_void_null_func
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+
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+/*
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+.weak __malloc_init
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+__malloc_init = _void_void_null_func
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+*/
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+
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+.weak __init_stdio
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+__init_stdio = _void_void_null_func
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+
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+.weak __stdio_close_all
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+__stdio_close_all = _void_void_null_func
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+
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+.data
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+__environ:
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+ .long 0
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+.weak environ
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+.align 4
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+environ = __environ
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+
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+.data
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+__errno:
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+ .long 0
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+.weak errno
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+.align 4
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+errno = __errno
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Eric Andersen