gdb/arm-symbian-tdep.c

   1 /* ARM Symbian OS target support.
   2
   3    Copyright (C) 2008-2015 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "frame.h"
  22 #include "objfiles.h"
  23 #include "osabi.h"
  24 #include "solib.h"
  25 #include "solib-target.h"
  26 #include "target.h"
  27 #include "elf-bfd.h"
  28
  29 /* If PC is in a DLL import stub, return the address of the `real'
  30    function belonging to the stub.  */
  31
  32 static CORE_ADDR
  33 arm_symbian_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
  34 {
  35   struct gdbarch *gdbarch;
  36   enum bfd_endian byte_order;
  37   ULONGEST insn;
  38   CORE_ADDR dest;
  39   gdb_byte buf[4];
  40
  41   if (!in_plt_section (pc))
  42     return 0;
  43
  44   if (target_read_memory (pc, buf, 4) != 0)
  45     return 0;
  46
  47   gdbarch = get_frame_arch (frame);
  48   byte_order = gdbarch_byte_order (gdbarch);
  49
  50   /* ldr pc, [pc, #-4].  */
  51   insn = extract_unsigned_integer (buf, 4, byte_order);
  52   if (insn != 0xe51ff004)
  53     return 0;
  54
  55   if (target_read_memory (pc + 4, buf, 4) != 0)
  56     return 0;
  57
  58   dest = extract_unsigned_integer (buf, 4, byte_order);
  59   return gdbarch_addr_bits_remove (gdbarch, dest);
  60 }
  61
  62 static void
  63 arm_symbian_init_abi (struct gdbarch_info info,
  64                       struct gdbarch *gdbarch)
  65 {
  66   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  67
  68   /* Shared library handling.  */
  69   set_gdbarch_skip_trampoline_code (gdbarch, arm_symbian_skip_trampoline_code);
  70
  71   /* On this target, the toolchain outputs ELF files, with `sym' for
  72      filename extension (e.g., `FOO.sym'); these are post-linker
  73      processed into PE-ish DLLs (e.g., `FOO.dll'), and it's these that
  74      are actually copied to and run on the target.  Naturally, when
  75      listing shared libraries, Symbian stubs report the DLL filenames.
  76      Setting this makes it so that GDB automatically looks for the
  77      corresponding ELF files on the host's filesystem.  */
  78   set_gdbarch_solib_symbols_extension (gdbarch, "sym");
  79
  80   /* Canonical paths on this target look like `c:\sys\bin\bar.dll',
  81      for example.  */
  82   set_gdbarch_has_dos_based_file_system (gdbarch, 1);
  83
  84   set_solib_ops (gdbarch, &solib_target_so_ops);
  85 }
  86
  87 /* Recognize Symbian object files.  */
  88
  89 static enum gdb_osabi
  90 arm_symbian_osabi_sniffer (bfd *abfd)
  91 {
  92   Elf_Internal_Phdr *phdrs;
  93   long phdrs_size;
  94   int num_phdrs, i;
  95
  96   /* Symbian executables are always shared objects (ET_DYN).  */
  97   if (elf_elfheader (abfd)->e_type == ET_EXEC)
  98     return GDB_OSABI_UNKNOWN;
  99
 100   if (elf_elfheader (abfd)->e_ident[EI_OSABI] != ELFOSABI_NONE)
 101     return GDB_OSABI_UNKNOWN;
 102
 103   /* Check for the ELF headers not being part of any PT_LOAD segment.
 104      Symbian is the only GDB supported (or GNU binutils supported) ARM
 105      target which uses a postlinker to flatten ELF files, dropping the
 106      ELF dynamic info in the process.  */
 107   phdrs_size = bfd_get_elf_phdr_upper_bound (abfd);
 108   if (phdrs_size == -1)
 109     return GDB_OSABI_UNKNOWN;
 110
 111   phdrs = (Elf_Internal_Phdr *) alloca (phdrs_size);
 112   num_phdrs = bfd_get_elf_phdrs (abfd, phdrs);
 113   if (num_phdrs == -1)
 114     return GDB_OSABI_UNKNOWN;
 115
 116   for (i = 0; i < num_phdrs; i++)
 117     if (phdrs[i].p_type == PT_LOAD && phdrs[i].p_offset == 0)
 118       return GDB_OSABI_UNKNOWN;
 119
 120   /* Looks like a Symbian binary.  */
 121   return GDB_OSABI_SYMBIAN;
 122 }
 123
 124 /* -Wmissing-prototypes */
 125 extern initialize_file_ftype _initialize_arm_symbian_tdep;
 126
 127 void
 128 _initialize_arm_symbian_tdep (void)
 129 {
 130   gdbarch_register_osabi_sniffer (bfd_arch_arm,
 131                                   bfd_target_elf_flavour,
 132                                   arm_symbian_osabi_sniffer);
 133
 134   gdbarch_register_osabi (bfd_arch_arm, 0, GDB_OSABI_SYMBIAN,
 135                           arm_symbian_init_abi);
 136 }