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   set_solib_ops (gdbarch, &solib_target_so_ops);
  82 }
  83
  84 /* Recognize Symbian object files.  */
  85
  86 static enum gdb_osabi
  87 arm_symbian_osabi_sniffer (bfd *abfd)
  88 {
  89   Elf_Internal_Phdr *phdrs, **segments;
  90   long phdrs_size;
  91   int num_phdrs, i;
  92
  93   /* Symbian executables are always shared objects (ET_DYN).  */
  94   if (elf_elfheader (abfd)->e_type == ET_EXEC)
  95     return GDB_OSABI_UNKNOWN;
  96
  97   if (elf_elfheader (abfd)->e_ident[EI_OSABI] != ELFOSABI_NONE)
  98     return GDB_OSABI_UNKNOWN;
  99
 100   /* Check for the ELF headers not being part of any PT_LOAD segment.
 101      Symbian is the only GDB supported (or GNU binutils supported) ARM
 102      target which uses a postlinker to flatten ELF files, dropping the
 103      ELF dynamic info in the process.  */
 104   phdrs_size = bfd_get_elf_phdr_upper_bound (abfd);
 105   if (phdrs_size == -1)
 106     return GDB_OSABI_UNKNOWN;
 107
 108   phdrs = alloca (phdrs_size);
 109   num_phdrs = bfd_get_elf_phdrs (abfd, phdrs);
 110   if (num_phdrs == -1)
 111     return GDB_OSABI_UNKNOWN;
 112
 113   for (i = 0; i < num_phdrs; i++)
 114     if (phdrs[i].p_type == PT_LOAD && phdrs[i].p_offset == 0)
 115       return GDB_OSABI_UNKNOWN;
 116
 117   /* Looks like a Symbian binary.  */
 118   return GDB_OSABI_SYMBIAN;
 119 }
 120
 121 void
 122 _initialize_arm_symbian_tdep (void)
 123 {
 124   gdbarch_register_osabi_sniffer (bfd_arch_arm,
 125                                   bfd_target_elf_flavour,
 126                                   arm_symbian_osabi_sniffer);
 127
 128   gdbarch_register_osabi (bfd_arch_arm, 0, GDB_OSABI_SYMBIAN,
 129                           arm_symbian_init_abi);
 130 }