gdb/arm-wince-tdep.c

   1 /* Target-dependent code for Windows CE running on ARM processors,
   2    for GDB.
   3
   4    Copyright (C) 2007-2015 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 "frame.h"
  26
  27 #include "arm-tdep.h"
  28 #include "windows-tdep.h"
  29
  30 static const gdb_byte arm_wince_le_breakpoint[] = { 0x10, 0x00, 0x00, 0xe6 };
  31 static const gdb_byte arm_wince_thumb_le_breakpoint[] = { 0xfe, 0xdf };
  32
  33 /* Description of the longjmp buffer.  */
  34 #define ARM_WINCE_JB_ELEMENT_SIZE       INT_REGISTER_SIZE
  35 #define ARM_WINCE_JB_PC                 10
  36
  37 static CORE_ADDR
  38 arm_pe_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
  39 {
  40   struct gdbarch *gdbarch = get_frame_arch (frame);
  41   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  42   ULONGEST indirect;
  43   struct bound_minimal_symbol indsym;
  44   const char *symname;
  45   CORE_ADDR next_pc;
  46
  47   /* The format of an ARM DLL trampoline is:
  48
  49        ldr  ip, [pc]
  50        ldr  pc, [ip]
  51        .dw __imp_<func>
  52
  53   */
  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.minsym == NULL)
  66     return 0;
  67
  68   symname = MSYMBOL_LINKAGE_NAME (indsym.minsym);
  69   if (symname == NULL || !startswith (symname, "__imp_"))
  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 static 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 bound_minimal_symbol s = lookup_minimal_symbol_by_pc (call_dest);
 104
 105       if (s.minsym != NULL
 106           && MSYMBOL_LINKAGE_NAME (s.minsym) != NULL
 107           && strcmp (MSYMBOL_LINKAGE_NAME (s.minsym), "__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   windows_init_abi (info, gdbarch);
 120
 121   tdep->arm_breakpoint = arm_wince_le_breakpoint;
 122   tdep->arm_breakpoint_size = sizeof (arm_wince_le_breakpoint);
 123   tdep->thumb_breakpoint = arm_wince_thumb_le_breakpoint;
 124   tdep->thumb_breakpoint_size = sizeof (arm_wince_thumb_le_breakpoint);
 125   tdep->struct_return = pcc_struct_return;
 126
 127   tdep->fp_model = ARM_FLOAT_SOFT_VFP;
 128
 129   tdep->jb_pc = ARM_WINCE_JB_PC;
 130   tdep->jb_elt_size = ARM_WINCE_JB_ELEMENT_SIZE;
 131
 132   /* On ARM WinCE char defaults to signed.  */
 133   set_gdbarch_char_signed (gdbarch, 1);
 134
 135   /* Shared library handling.  */
 136   set_gdbarch_skip_trampoline_code (gdbarch, arm_pe_skip_trampoline_code);
 137
 138   /* Single stepping.  */
 139   set_gdbarch_software_single_step (gdbarch, arm_software_single_step);
 140
 141   /* Skip call to __gccmain that gcc places in main.  */
 142   set_gdbarch_skip_main_prologue (gdbarch, arm_wince_skip_main_prologue);
 143 }
 144
 145 static enum gdb_osabi
 146 arm_wince_osabi_sniffer (bfd *abfd)
 147 {
 148   const char *target_name = bfd_get_target (abfd);
 149
 150   if (strcmp (target_name, "pei-arm-wince-little") == 0)
 151     return GDB_OSABI_WINCE;
 152
 153   return GDB_OSABI_UNKNOWN;
 154 }
 155
 156 /* Provide a prototype to silence -Wmissing-prototypes.  */
 157 void _initialize_arm_wince_tdep (void);
 158
 159 void
 160 _initialize_arm_wince_tdep (void)
 161 {
 162   gdbarch_register_osabi_sniffer (bfd_arch_arm, bfd_target_coff_flavour,
 163                                   arm_wince_osabi_sniffer);
 164
 165   gdbarch_register_osabi (bfd_arch_arm, 0, GDB_OSABI_WINCE,
 166                           arm_wince_init_abi);
 167 }