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/* Copyright (C) 1991, 1992 Free Software Foundation, Inc.
This file is part of the GNU C Library.

The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

The GNU C Library 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
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.  */


/*  Based on the code from GNU libc, but hacked up by John Beppu and Erik Andersen */
/*  adapted by PaX Team for ET_DYN/PIE binaries */

/*
    When we enter this piece of code, the program stack looks like this:
        argc            argument counter (integer)
        argv[0]         program name (pointer)
        argv[1...N]     program args (pointers)
        argv[argc-1]    end of args (integer)
        NULL
        env[0...N]      environment variables (pointers)
        NULL
*/

#include <features.h>

.text
        .align 4

        .global _start
        .type   _start,%function
#if defined L_crt0 || defined L_Scrt0 || ! defined __UCLIBC_CTOR_DTOR__
        .type   __uClibc_main,%function
#else
        .weak   _init
        .weak   _fini
        .type   __uClibc_start_main,%function
#endif
/* Stick in a dummy reference to main(), so that if an application
 * is linking when the main() function is in a static library (.a)
 * we can be sure that main() actually gets linked in */
        .type   main,%function

_start:
        /* locate the start of the environment variables */
        popl %ecx       /* Store argc into %ecx */
        movl %esp,%ebx  /* Store argv into ebx */
        movl %esp,%eax  /* Store argv into eax as well*/
        movl %ecx,%edx  /* Stick argc into %edx so we can do some math in a sec */
        leal 4(%eax,%edx,4),%eax

        /*  [ register layout ]

            sizeof(char*) == 4
            %ecx = argc     ; 0(esp)
            %ebx = argv     ; 4(esp)
            %eax = env      ; argv + (argc * 4) + 4
        */

        /* Set up an invalid (NULL return address, NULL frame pointer)
           callers stack frame so anybody unrolling the stack knows where
           to stop */
        xorl %ebp,%ebp  /* NULL */
        pushl %ebp      /* callers %cs */
        pushl %ebp      /* callers %eip (return address) */
        pushl %ebp      /* callers %ebp (frame pointer) */
        movl %esp,%ebp  /* mark callers stack frame as invalid */

#if defined L_Scrt0 || defined L_Scrt1
        call .L0
.L0:
        pop %edx
        addl $_GLOBAL_OFFSET_TABLE_+[.-.L0],%edx
#endif

#if (defined L_crt1 || defined L_Scrt1 || defined L_gcrt1 ) && defined __UCLIBC_CTOR_DTOR__
        /* Push .init and .fini arguments to __uClibc_start_main() on the stack */
#ifdef L_Scrt1
        pushl _fini@GOT(%edx)
        pushl _init@GOT(%edx)
#else
        pushl $_fini
        pushl $_init
#endif

        /* Push envp, argc, and argc arguments to __uClibc_start_main() on the stack */ 
        pushl %eax      /* Environment pointer */
        pushl %ebx      /* Argument pointer */
        pushl %ecx      /* And the argument count */

        /* Ok, now run uClibc's main() -- shouldn't return */
#ifdef L_Scrt1
        call *__uClibc_start_main@GOT(%edx)
#else
        call __uClibc_start_main
#endif
#else
        /* Push envp, argc, and argc arguments to __uClibc_start_main() on the stack */ 
        pushl %eax      /* Environment pointer */
        pushl %ebx      /* Argument pointer */
        pushl %ecx      /* And the argument count */

#ifdef L_Scrt0
        call *__uClibc_main@GOT(%edx)
#else
        call __uClibc_main
#endif
#endif

        /* Crash if somehow `exit' returns anyways.  */
        hlt
.size _start,.-_start


#if defined L_gcrt1 && defined __UCLIBC_PROFILING__
# include "./gmon-start.S"
#endif