gdb/arm-wince-tdep.c

/* Target-dependent code for Windows CE running on ARM processors,
   for GDB.

   Copyright (C) 2007, 2008, 2009 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 "osabi.h"
#include "gdbcore.h"
#include "target.h"
#include "solib.h"
#include "solib-target.h"
#include "frame.h"

#include "gdb_string.h"

#include "arm-tdep.h"

static const char arm_wince_le_breakpoint[] = { 0x10, 0x00, 0x00, 0xe6 };
static const char arm_wince_thumb_le_breakpoint[] = { 0xfe, 0xdf };

/* Description of the longjmp buffer.  */
#define ARM_WINCE_JB_ELEMENT_SIZE	INT_REGISTER_SIZE
#define ARM_WINCE_JB_PC			10

static CORE_ADDR
arm_pe_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
{
  struct gdbarch *gdbarch = get_frame_arch (frame);
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  ULONGEST indirect;
  struct minimal_symbol *indsym;
  char *symname;
  CORE_ADDR next_pc;

  /* The format of an ARM DLL trampoline is:
       ldr  ip, [pc]
       ldr  pc, [ip]
       .dw __imp_<func>  */

  if (pc == 0
      || read_memory_unsigned_integer (pc + 0, 4, byte_order) != 0xe59fc000
      || read_memory_unsigned_integer (pc + 4, 4, byte_order) != 0xe59cf000)
    return 0;

  indirect = read_memory_unsigned_integer (pc + 8, 4, byte_order);
  if (indirect == 0)
    return 0;

  indsym = lookup_minimal_symbol_by_pc (indirect);
  if (indsym == NULL)
    return 0;

  symname = SYMBOL_LINKAGE_NAME (indsym);
  if (symname == NULL || strncmp (symname, "__imp_", 6) != 0)
    return 0;

  next_pc = read_memory_unsigned_integer (indirect, 4, byte_order);
  if (next_pc != 0)
    return next_pc;

  /* Check with the default arm gdbarch_skip_trampoline.  */
  return arm_skip_stub (frame, pc);
}

/* GCC emits a call to __gccmain in the prologue of main.

   The function below examines the code pointed at by PC and checks to
   see if it corresponds to a call to __gccmain.  If so, it returns
   the address of the instruction following that call.  Otherwise, it
   simply returns PC.  */

CORE_ADDR
arm_wince_skip_main_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
{
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  ULONGEST this_instr;

  this_instr = read_memory_unsigned_integer (pc, 4, byte_order);

  /* bl offset <__gccmain> */
  if ((this_instr & 0xfff00000) == 0xeb000000)
    {
#define sign_extend(V, N) \
  (((long) (V) ^ (1L << ((N) - 1))) - (1L << ((N) - 1)))

      long offset = sign_extend (this_instr & 0x000fffff, 23) << 2;
      CORE_ADDR call_dest = (pc + 8 + offset) & 0xffffffffU;
      struct minimal_symbol *s = lookup_minimal_symbol_by_pc (call_dest);

      if (s != NULL
	  && SYMBOL_LINKAGE_NAME (s) != NULL
	  && strcmp (SYMBOL_LINKAGE_NAME (s), "__gccmain") == 0)
	pc += 4;
    }

  return pc;
}

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

  tdep->arm_breakpoint = arm_wince_le_breakpoint;
  tdep->arm_breakpoint_size = sizeof (arm_wince_le_breakpoint);
  tdep->thumb_breakpoint = arm_wince_thumb_le_breakpoint;
  tdep->thumb_breakpoint_size = sizeof (arm_wince_thumb_le_breakpoint);
  tdep->struct_return = pcc_struct_return;

  tdep->fp_model = ARM_FLOAT_SOFT_VFP;

  tdep->jb_pc = ARM_WINCE_JB_PC;
  tdep->jb_elt_size = ARM_WINCE_JB_ELEMENT_SIZE;

  /* On ARM WinCE char defaults to signed.  */
  set_gdbarch_char_signed (gdbarch, 1);

  /* Shared library handling.  */
  set_solib_ops (gdbarch, &solib_target_so_ops);
  set_gdbarch_skip_trampoline_code (gdbarch, arm_pe_skip_trampoline_code);

  /* Single stepping.  */
  set_gdbarch_software_single_step (gdbarch, arm_software_single_step);

  /* Skip call to __gccmain that gcc places in main.  */
  set_gdbarch_skip_main_prologue (gdbarch, arm_wince_skip_main_prologue);
}

static enum gdb_osabi
arm_wince_osabi_sniffer (bfd *abfd)
{
  const char *target_name = bfd_get_target (abfd);

  if (strcmp (target_name, "pei-arm-wince-little") == 0)
    return GDB_OSABI_WINCE;

  return GDB_OSABI_UNKNOWN;
}

/* Provide a prototype to silence -Wmissing-prototypes.  */
void _initialize_arm_wince_tdep (void);

void
_initialize_arm_wince_tdep (void)
{
  gdbarch_register_osabi_sniffer (bfd_arch_arm, bfd_target_coff_flavour,
                                  arm_wince_osabi_sniffer);

  gdbarch_register_osabi (bfd_arch_arm, 0, GDB_OSABI_WINCE,
                          arm_wince_init_abi);
}