/* ARM Symbian OS target support.

   Copyright (C) 2008, 2009, 2010
   Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "frame.h"
#include "objfiles.h"
#include "osabi.h"
#include "solib.h"
#include "solib-target.h"
#include "target.h"
#include "elf-bfd.h"

/* If PC is in a DLL import stub, return the address of the `real'
   function belonging to the stub.  */

CORE_ADDR
arm_symbian_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
{
  struct gdbarch *gdbarch;
  enum bfd_endian byte_order;
  ULONGEST insn;
  CORE_ADDR dest;
  gdb_byte buf[4];

  if (!in_plt_section (pc, NULL))
    return 0;

  if (target_read_memory (pc, buf, 4) != 0)
    return 0;

  gdbarch = get_frame_arch (frame);
  byte_order = gdbarch_byte_order (gdbarch);

  /* ldr pc, [pc, #-4].  */
  insn = extract_unsigned_integer (buf, 4, byte_order);
  if (insn != 0xe51ff004)
    return 0;

  if (target_read_memory (pc + 4, buf, 4) != 0)
    return 0;

  dest = extract_unsigned_integer (buf, 4, byte_order);
  return gdbarch_addr_bits_remove (gdbarch, dest);
}

static void
arm_symbian_init_abi (struct gdbarch_info info,
		      struct gdbarch *gdbarch)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  /* Shared library handling.  */
  set_gdbarch_skip_trampoline_code (gdbarch, arm_symbian_skip_trampoline_code);

  set_solib_ops (gdbarch, &solib_target_so_ops);
}

/* Recognize Symbian object files.  */

static enum gdb_osabi
arm_symbian_osabi_sniffer (bfd *abfd)
{
  Elf_Internal_Phdr *phdrs, **segments;
  long phdrs_size;
  int num_phdrs, i;

  /* Symbian executables are always shared objects (ET_DYN).  */
  if (elf_elfheader (abfd)->e_type == ET_EXEC)
    return GDB_OSABI_UNKNOWN;

  if (elf_elfheader (abfd)->e_ident[EI_OSABI] != ELFOSABI_NONE)
    return GDB_OSABI_UNKNOWN;

  /* Check for the ELF headers not being part of any PT_LOAD segment.
     Symbian is the only GDB supported (or GNU binutils supported) ARM
     target which uses a postlinker to flatten ELF files, dropping the
     ELF dynamic info in the process.  */
  phdrs_size = bfd_get_elf_phdr_upper_bound (abfd);
  if (phdrs_size == -1)
    return GDB_OSABI_UNKNOWN;

  phdrs = alloca (phdrs_size);
  num_phdrs = bfd_get_elf_phdrs (abfd, phdrs);
  if (num_phdrs == -1)
    return GDB_OSABI_UNKNOWN;

  for (i = 0; i < num_phdrs; i++)
    if (phdrs[i].p_type == PT_LOAD && phdrs[i].p_offset == 0)
      return GDB_OSABI_UNKNOWN;

  /* Looks like a Symbian binary.  */
  return GDB_OSABI_SYMBIAN;
}

void
_initialize_arm_symbian_tdep (void)
{
  gdbarch_register_osabi_sniffer (bfd_arch_arm,
				  bfd_target_elf_flavour,
				  arm_symbian_osabi_sniffer);

  gdbarch_register_osabi (bfd_arch_arm, 0, GDB_OSABI_SYMBIAN,
			  arm_symbian_init_abi);
}