gdb/arm-symbian-tdep.c

   1 /* ARM Symbian OS target support.
   2
   3    Copyright (C) 2008, 2009, 2010
   4    Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include "defs.h"
  22 #include "frame.h"
  23 #include "objfiles.h"
  24 #include "osabi.h"
  25 #include "solib.h"
  26 #include "solib-target.h"
  27 #include "target.h"
  28 #include "elf-bfd.h"
  29
  30 /* If PC is in a DLL import stub, return the address of the `real'
  31    function belonging to the stub.  */
  32
  33 CORE_ADDR
  34 arm_symbian_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
  35 {
  36   struct gdbarch *gdbarch;
  37   enum bfd_endian byte_order;
  38   ULONGEST insn;
  39   CORE_ADDR dest;
  40   gdb_byte buf[4];
  41
  42   if (!in_plt_section (pc, NULL))
  43     return 0;
  44
  45   if (target_read_memory (pc, buf, 4) != 0)
  46     return 0;
  47
  48   gdbarch = get_frame_arch (frame);
  49   byte_order = gdbarch_byte_order (gdbarch);
  50
  51   /* ldr pc, [pc, #-4].  */
  52   insn = extract_unsigned_integer (buf, 4, byte_order);
  53   if (insn != 0xe51ff004)
  54     return 0;
  55
  56   if (target_read_memory (pc + 4, buf, 4) != 0)
  57     return 0;
  58
  59   dest = extract_unsigned_integer (buf, 4, byte_order);
  60   return gdbarch_addr_bits_remove (gdbarch, dest);
  61 }
  62
  63 static void
  64 arm_symbian_init_abi (struct gdbarch_info info,
  65                       struct gdbarch *gdbarch)
  66 {
  67   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  68
  69   /* Shared library handling.  */
  70   set_gdbarch_skip_trampoline_code (gdbarch, arm_symbian_skip_trampoline_code);
  71
  72   /* On this target, the toolchain outputs ELF files, with `sym' for
  73      filename extension (e.g., `FOO.sym'); these are post-linker
  74      processed into PE-ish DLLs (e.g., `FOO.dll'), and it's these that
  75      are actually copied to and run on the target.  Naturally, when
  76      listing shared libraries, Symbian stubs report the DLL filenames.
  77      Setting this makes it so that GDB automatically looks for the
  78      corresponding ELF files on the host's filesystem.  */
  79   set_gdbarch_solib_symbols_extension (gdbarch, "sym");
  80
  81   /* Canonical paths on this target look like `c:\sys\bin\bar.dll',
  82      for example.  */
  83   set_gdbarch_has_dos_based_file_system (gdbarch, 1);
  84
  85   set_solib_ops (gdbarch, &solib_target_so_ops);
  86 }
  87
  88 /* Recognize Symbian object files.  */
  89
  90 static enum gdb_osabi
  91 arm_symbian_osabi_sniffer (bfd *abfd)
  92 {
  93   Elf_Internal_Phdr *phdrs, **segments;
  94   long phdrs_size;
  95   int num_phdrs, i;
  96
  97   /* Symbian executables are always shared objects (ET_DYN).  */
  98   if (elf_elfheader (abfd)->e_type == ET_EXEC)
  99     return GDB_OSABI_UNKNOWN;
 100
 101   if (elf_elfheader (abfd)->e_ident[EI_OSABI] != ELFOSABI_NONE)
 102     return GDB_OSABI_UNKNOWN;
 103
 104   /* Check for the ELF headers not being part of any PT_LOAD segment.
 105      Symbian is the only GDB supported (or GNU binutils supported) ARM
 106      target which uses a postlinker to flatten ELF files, dropping the
 107      ELF dynamic info in the process.  */
 108   phdrs_size = bfd_get_elf_phdr_upper_bound (abfd);
 109   if (phdrs_size == -1)
 110     return GDB_OSABI_UNKNOWN;
 111
 112   phdrs = alloca (phdrs_size);
 113   num_phdrs = bfd_get_elf_phdrs (abfd, phdrs);
 114   if (num_phdrs == -1)
 115     return GDB_OSABI_UNKNOWN;
 116
 117   for (i = 0; i < num_phdrs; i++)
 118     if (phdrs[i].p_type == PT_LOAD && phdrs[i].p_offset == 0)
 119       return GDB_OSABI_UNKNOWN;
 120
 121   /* Looks like a Symbian binary.  */
 122   return GDB_OSABI_SYMBIAN;
 123 }
 124
 125 void
 126 _initialize_arm_symbian_tdep (void)
 127 {
 128   gdbarch_register_osabi_sniffer (bfd_arch_arm,
 129                                   bfd_target_elf_flavour,
 130                                   arm_symbian_osabi_sniffer);
 131
 132   gdbarch_register_osabi (bfd_arch_arm, 0, GDB_OSABI_SYMBIAN,
 133                           arm_symbian_init_abi);
 134 }