uclibc-ng/libc/sysdeps/linux/arm/crtreloc.c

/* Copyright (C) 2003, 2004 Free Software Foundation, Inc.
   written by Alexandre Oliva <aoliva@redhat.com>
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 Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.

In addition to the permissions in the GNU Lesser General Public
License, the Free Software Foundation gives you unlimited
permission to link the compiled version of this file with other
programs, and to distribute those programs without any restriction
coming from the use of this file.  (The GNU Lesser General Public
License restrictions do apply in other respects; for example, they
cover modification of the file, and distribution when not linked
into another program.)

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 Lesser General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, see <http://www.gnu.org/licenses/>.  */

#ifdef __FDPIC__

#include <sys/types.h>
#include <link.h>

/* This file is to be compiled into crt object files, to enable
   executables to easily self-relocate.  */

union word {
    char c[4];
    void *v;
};

/* Compute the runtime address of pointer in the range [p,e), and then
   map the pointer pointed by it.  */
static __always_inline void ***
reloc_range_indirect (void ***p, void ***e,
		      const struct elf32_fdpic_loadmap *map)
{
  while (p < e)
    {
      if (*p != (void **)-1)
	{
	  void *ptr = __reloc_pointer (*p, map);
	  if (ptr != (void *)-1)
	    {
	      void *pt;
	      if ((long)ptr & 3)
		{
		  unsigned char *c = ptr;
		  int i;
		  unsigned long v = 0;
		  for (i = 0; i < 4; i++)
		    v |= c[i] << 8 * i;
		  pt = (void *)v;
		}
	      else
		pt = *(void**)ptr;
	      pt = __reloc_pointer (pt, map);
	      if ((long)ptr & 3)
		{
		  unsigned char *c = ptr;
		  int i;
		  unsigned long v = (unsigned long)pt;
		  for (i = 0; i < 4; i++, v >>= 8)
		    c[i] = v;
		}
	      else
		*(void**)ptr = pt;
	    }
	}
      p++;
    }
  return p;
}

/* Call __reloc_range_indirect for the given range except for the last
   entry, whose contents are only relocated.  It's expected to hold
   the GOT value.  */
attribute_hidden void*
__self_reloc (const struct elf32_fdpic_loadmap *map,
	      void ***p, void ***e)
{
  p = reloc_range_indirect (p, e-1, map);

  if (p >= e)
    return (void*)-1;

  return __reloc_pointer (*p, map);
}

#if 0
/* These are other functions that might be useful, but that we don't
   need.  */

/* Remap pointers in [p,e).  */
static __always_inline void**
reloc_range (void **p, void **e,
	     const struct elf32_fdpic_loadmap *map)
{
  while (p < e)
    {
      *p = __reloc_pointer (*p, map);
      p++;
    }
  return p;
}

/* Remap p, adjust e by the same offset, then map the pointers in the
   range determined by them.  */
void attribute_hidden
__reloc_range (const struct elf32_fdpic_loadmap *map,
	       void **p, void **e)
{
  void **old = p;

  p = __reloc_pointer (p, map);
  e += p - old;
  reloc_range (p, e, map);
}

/* Remap p, adjust e by the same offset, then map pointers referenced
   by the (unadjusted) pointers in the range.  Return the relocated
   value of the last pointer in the range.  */
void* attribute_hidden
__reloc_range_indirect (const struct elf32_fdpic_loadmap *map,
			void ***p, void ***e)
{
  void ***old = p;

  p = __reloc_pointer (p, map);
  e += p - old;
  return reloc_range_indirect (p, e, map);
}
#endif

#endif /* __FDPIC__ */