gdb/arm-wince-tdep.c

   1 /* Target-dependent code for Windows CE running on ARM processors,
   2    for GDB.
   3
   4    Copyright (C) 2007, 2008, 2009 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 "osabi.h"
  23 #include "gdbcore.h"
  24 #include "target.h"
  25 #include "solib.h"
  26 #include "solib-target.h"
  27 #include "frame.h"
  28
  29 #include "gdb_string.h"
  30
  31 #include "arm-tdep.h"
  32
  33 static const char arm_wince_le_breakpoint[] = { 0x10, 0x00, 0x00, 0xe6 };
  34 static const char arm_wince_thumb_le_breakpoint[] = { 0xfe, 0xdf };
  35
  36 /* Description of the longjmp buffer.  */
  37 #define ARM_WINCE_JB_ELEMENT_SIZE       INT_REGISTER_SIZE
  38 #define ARM_WINCE_JB_PC                 10
  39
  40 static CORE_ADDR
  41 arm_pe_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
  42 {
  43   struct gdbarch *gdbarch = get_frame_arch (frame);
  44   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  45   ULONGEST indirect;
  46   struct minimal_symbol *indsym;
  47   char *symname;
  48   CORE_ADDR next_pc;
  49
  50   /* The format of an ARM DLL trampoline is:
  51        ldr  ip, [pc]
  52        ldr  pc, [ip]
  53        .dw __imp_<func>  */
  54
  55   if (pc == 0
  56       || read_memory_unsigned_integer (pc + 0, 4, byte_order) != 0xe59fc000
  57       || read_memory_unsigned_integer (pc + 4, 4, byte_order) != 0xe59cf000)
  58     return 0;
  59
  60   indirect = read_memory_unsigned_integer (pc + 8, 4, byte_order);
  61   if (indirect == 0)
  62     return 0;
  63
  64   indsym = lookup_minimal_symbol_by_pc (indirect);
  65   if (indsym == NULL)
  66     return 0;
  67
  68   symname = SYMBOL_LINKAGE_NAME (indsym);
  69   if (symname == NULL || strncmp (symname, "__imp_", 6) != 0)
  70     return 0;
  71
  72   next_pc = read_memory_unsigned_integer (indirect, 4, byte_order);
  73   if (next_pc != 0)
  74     return next_pc;
  75
  76   /* Check with the default arm gdbarch_skip_trampoline.  */
  77   return arm_skip_stub (frame, pc);
  78 }
  79
  80 /* GCC emits a call to __gccmain in the prologue of main.
  81
  82    The function below examines the code pointed at by PC and checks to
  83    see if it corresponds to a call to __gccmain.  If so, it returns
  84    the address of the instruction following that call.  Otherwise, it
  85    simply returns PC.  */
  86
  87 CORE_ADDR
  88 arm_wince_skip_main_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
  89 {
  90   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  91   ULONGEST this_instr;
  92
  93   this_instr = read_memory_unsigned_integer (pc, 4, byte_order);
  94
  95   /* bl offset <__gccmain> */
  96   if ((this_instr & 0xfff00000) == 0xeb000000)
  97     {
  98 #define sign_extend(V, N) \
  99   (((long) (V) ^ (1L << ((N) - 1))) - (1L << ((N) - 1)))
 100
 101       long offset = sign_extend (this_instr & 0x000fffff, 23) << 2;
 102       CORE_ADDR call_dest = (pc + 8 + offset) & 0xffffffffU;
 103       struct minimal_symbol *s = lookup_minimal_symbol_by_pc (call_dest);
 104
 105       if (s != NULL
 106           && SYMBOL_LINKAGE_NAME (s) != NULL
 107           && strcmp (SYMBOL_LINKAGE_NAME (s), "__gccmain") == 0)
 108         pc += 4;
 109     }
 110
 111   return pc;
 112 }
 113
 114 static void
 115 arm_wince_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 116 {
 117   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 118
 119   tdep->arm_breakpoint = arm_wince_le_breakpoint;
 120   tdep->arm_breakpoint_size = sizeof (arm_wince_le_breakpoint);
 121   tdep->thumb_breakpoint = arm_wince_thumb_le_breakpoint;
 122   tdep->thumb_breakpoint_size = sizeof (arm_wince_thumb_le_breakpoint);
 123   tdep->struct_return = pcc_struct_return;
 124
 125   tdep->fp_model = ARM_FLOAT_SOFT_VFP;
 126
 127   tdep->jb_pc = ARM_WINCE_JB_PC;
 128   tdep->jb_elt_size = ARM_WINCE_JB_ELEMENT_SIZE;
 129
 130   /* On ARM WinCE char defaults to signed.  */
 131   set_gdbarch_char_signed (gdbarch, 1);
 132
 133   /* Shared library handling.  */
 134   set_solib_ops (gdbarch, &solib_target_so_ops);
 135   set_gdbarch_skip_trampoline_code (gdbarch, arm_pe_skip_trampoline_code);
 136
 137   /* Single stepping.  */
 138   set_gdbarch_software_single_step (gdbarch, arm_software_single_step);
 139
 140   /* Skip call to __gccmain that gcc places in main.  */
 141   set_gdbarch_skip_main_prologue (gdbarch, arm_wince_skip_main_prologue);
 142 }
 143
 144 static enum gdb_osabi
 145 arm_wince_osabi_sniffer (bfd *abfd)
 146 {
 147   const char *target_name = bfd_get_target (abfd);
 148
 149   if (strcmp (target_name, "pei-arm-wince-little") == 0)
 150     return GDB_OSABI_WINCE;
 151
 152   return GDB_OSABI_UNKNOWN;
 153 }
 154
 155 /* Provide a prototype to silence -Wmissing-prototypes.  */
 156 void _initialize_arm_wince_tdep (void);
 157
 158 void
 159 _initialize_arm_wince_tdep (void)
 160 {
 161   gdbarch_register_osabi_sniffer (bfd_arch_arm, bfd_target_coff_flavour,
 162                                   arm_wince_osabi_sniffer);
 163
 164   gdbarch_register_osabi (bfd_arch_arm, 0, GDB_OSABI_WINCE,
 165                           arm_wince_init_abi);
 166 }