glibc/sysdeps/powerpc/elf/start.c

/* Startup code compliant to the ELF PowerPC ABI.
   Copyright (C) 1997 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., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

/* This is SVR4/PPC ABI compliant, and works under Linux when
   statically linked.  */

#include <unistd.h>
#include <stdlib.h>

/* Just a little assembler stub before gcc gets its hands on our
   stack pointer... */
asm ("\
	.section \".text\"
	.align 2
	.globl _start
_start:
 # save the stack pointer, in case we're statically linked under Linux
	mr 8,1
 # set up an initial stack frame, and clear the LR
	addi 1,1,-16
	clrrwi 1,1,4
	li 0,0
	stw 0,0(1)
	mtlr 0
 # set r13 to point at the 'small data area'
	lis 13,_SDA_BASE_@ha
	addi 13,13,_SDA_BASE_@l
 # and continue below.
	b __start1
0:
	.size	 _start,0b-_start
 # undo '.section text'.
	.previous
");

/* Define a symbol for the first piece of initialized data.  */
int __data_start = 0;
weak_alias (__data_start, data_start)

/* these probably should go, at least go somewhere else
   (sysdeps/mach/something?). */
void (*_mach_init_routine) (void);
void (*_thread_init_routine) (void);

extern void __libc_init_first (int argc, char **argv, char **envp);
extern int main (int argc, char **argv, char **envp, void *auxvec);
#ifdef HAVE_INITFINI
extern void _init (void);
extern void _fini (void);
#endif

#if 0
/* I'd like to say this, but it causes GCC to strip the whole procedure
   from the object file (this is sort of reasonable, because you've told
   GCC that the procedure is unused). :-( */
static void __start1(int argc, char **argv, char **envp,
		     void *auxvec, void (*exitfn) (void),
		     char **stack_on_entry)
     __attribute__ ((unused));

static
#endif
void
__start1(int argc, char **argv, char **envp,
	 void *auxvec, void (*exitfn) (void),
	 char **stack_on_entry)
{
  /* the PPC SVR4 ABI says that the top thing on the stack will
     be a NULL pointer, so if not we assume that we're being called
     as a statically-linked program by Linux...	 */
  if (*stack_on_entry != NULL)
    {
      /* ...in which case, we have argc as the top thing on the
	 stack, followed by argv (NULL-terminated), envp (likewise),
	 and the auxilary vector.  */
      argc = *(int *) stack_on_entry;
      argv = stack_on_entry + 1;
      envp = argv + argc + 1;
      auxvec = envp;
      while (*(char **) auxvec != NULL)
	++auxvec;
      ++auxvec;
      exitfn = NULL;
    }

  if (exitfn != NULL)
    atexit (exitfn);

  /* libc init routine, in case we are statically linked
     (otherwise ld.so will have called it when it loaded libc, but
     calling it twice doesn't hurt). */
  __libc_init_first (argc, argv, envp);

#ifdef HAVE_INITFINI
  /* ELF constructors/destructors */
  atexit (_fini);
  _init ();
#endif

  /* Stuff so we can build Mach/Linux executables (like vmlinux).  */
  if (_mach_init_routine != 0)
    _mach_init_routine ();
  if (_thread_init_routine != 0)
    _thread_init_routine ();

  /* the rest of the program */
  exit (main (argc, argv, envp, auxvec));
}