sysdeps/unix/arm/start.c

   1 /* Special startup code for ARM a.out binaries.
   2    Copyright (C) 1998, 2004, 2012 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    In addition to the permissions in the GNU Lesser General Public
  11    License, the Free Software Foundation gives you unlimited
  12    permission to link the compiled version of this file with other
  13    programs, and to distribute those programs without any restriction
  14    coming from the use of this file. (The GNU Lesser General Public
  15    License restrictions do apply in other respects; for example, they
  16    cover modification of the file, and distribution when not linked
  17    into another program.)
  18
  19    Note that people who make modified versions of this file are not
  20    obligated to grant this special exception for their modified
  21    versions; it is their choice whether to do so. The GNU Lesser
  22    General Public License gives permission to release a modified
  23    version without this exception; this exception also makes it
  24    possible to release a modified version which carries forward this
  25    exception.
  26
  27    The GNU C Library is distributed in the hope that it will be useful,
  28    but WITHOUT ANY WARRANTY; without even the implied warranty of
  29    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  30    Lesser General Public License for more details.
  31
  32    You should have received a copy of the GNU Lesser General Public
  33    License along with the GNU C Library.  If not, see
  34    <http://www.gnu.org/licenses/>.  */
  35
  36 #include <errno.h>
  37 #include <stdlib.h>
  38 #include <unistd.h>
  39 #include <sysdep.h>
  40
  41 /* The first piece of initialized data.  */
  42 int __data_start = 0;
  43 weak_alias (__data_start, data_start)
  44
  45 extern void __libc_init (int argc, char **argv, char **envp);
  46 extern int main (int argc, char **argv, char **envp);
  47
  48 /* N.B.: It is important that this be the first function.
  49    This file is the first thing in the text section.  */
  50
  51 /* If this was in C it might create its own stack frame and
  52    screw up the arguments.  */
  53 asm (".text; .globl _start; _start: B start1");
  54
  55 /* Fool gcc into thinking that more args are passed.  This makes it look
  56    on the stack (correctly) for the real arguments.  It causes somewhat
  57    strange register usage in start1(), but we aren't too bothered about
  58    that at the moment. */
  59 #define DUMMIES a1, a2, a3, a4
  60
  61 #ifdef  DUMMIES
  62 #define ARG_DUMMIES     DUMMIES,
  63 #define DECL_DUMMIES    int DUMMIES;
  64 #else
  65 #define ARG_DUMMIES
  66 #define DECL_DUMMIES
  67 #endif
  68
  69 /* ARGSUSED */
  70 static void
  71 start1 (ARG_DUMMIES argc, argv, envp)
  72      DECL_DUMMIES
  73      int argc;
  74      char **argv;
  75      char **envp;
  76 {
  77   /* Store a pointer to the environment.  */
  78   __environ = envp;
  79
  80   /* Do C library initializations.  */
  81   __libc_init (argc, argv, __environ);
  82
  83   /* Call the user program.  */
  84   exit (main (argc, argv, __environ));
  85 }