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   1 /*
   2  * Copyright (c) 2005, Kohsuke Ohtani
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the author nor the names of any co-contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  30 /*
  31  * crt0.S - C startup routine
  32  */
  34 /**
  35  * Stack layout:
  36  *      argc            argument counter (integer)
  37  *      argv[0]         program name (pointer)
  38  *      argv[1...N]     program args (pointers)
  39  *      argv[argc-1]    end of args (integer)
  40  *      NULL
  41  *      env[0...N]      environment variables (pointers)
  42  *      NULL
  43  */
  45 /*
  46  * Entry point called by kernel first
  47  */
  48         .text
  49         .global _start
  50 _start:
  51         popl    %ecx                    /* Get argc */
  52         movl    %esp, %ebx              /* Get argv */
  53         movl    %esp, %eax
  54         movl    %ecx, %edx
  55         leal    (%eax,%edx,4), %eax     /* Get envp */
  57         xorl    %ebp, %ebp              /* NULL */
  58         pushl   %ebp                    /* Set return address */
  59         pushl   %ebp
  61         pushl   %eax                    /* Set envp */
  62         pushl   %ebx                    /* Set argv */
  63         pushl   %ecx                    /* Set argc */
  64         call    __prex_main