gdb/arm-wince-tdep.c

   1 /* Target-dependent code for Windows CE running on ARM processors,
   2    for GDB.
   3
   4    Copyright (C) 2007-2021 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 "arch/arm.h"
  28 #include "arm-tdep.h"
  29 #include "windows-tdep.h"
  30
  31 static const gdb_byte arm_wince_le_breakpoint[] = { 0x10, 0x00, 0x00, 0xe6 };
  32 static const gdb_byte arm_wince_thumb_le_breakpoint[] = { 0xfe, 0xdf };
  33
  34 /* Description of the longjmp buffer.  */
  35 #define ARM_WINCE_JB_ELEMENT_SIZE       ARM_INT_REGISTER_SIZE
  36 #define ARM_WINCE_JB_PC                 10
  37
  38 static CORE_ADDR
  39 arm_pe_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
  40 {
  41   struct gdbarch *gdbarch = get_frame_arch (frame);
  42   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  43   ULONGEST indirect;
  44   struct bound_minimal_symbol indsym;
  45   const char *symname;
  46   CORE_ADDR next_pc;
  47
  48   /* The format of an ARM DLL trampoline is:
  49
  50        ldr  ip, [pc]
  51        ldr  pc, [ip]
  52        .dw __imp_<func>
  53
  54   */
  55
  56   if (pc == 0
  57       || read_memory_unsigned_integer (pc + 0, 4, byte_order) != 0xe59fc000
  58       || read_memory_unsigned_integer (pc + 4, 4, byte_order) != 0xe59cf000)
  59     return 0;
  60
  61   indirect = read_memory_unsigned_integer (pc + 8, 4, byte_order);
  62   if (indirect == 0)
  63     return 0;
  64
  65   indsym = lookup_minimal_symbol_by_pc (indirect);
  66   if (indsym.minsym == NULL)
  67     return 0;
  68
  69   symname = indsym.minsym->linkage_name ();
  70   if (symname == NULL || !startswith (symname, "__imp_"))
  71     return 0;
  72
  73   next_pc = read_memory_unsigned_integer (indirect, 4, byte_order);
  74   if (next_pc != 0)
  75     return next_pc;
  76
  77   /* Check with the default arm gdbarch_skip_trampoline.  */
  78   return arm_skip_stub (frame, pc);
  79 }
  80
  81 /* GCC emits a call to __gccmain in the prologue of main.
  82
  83    The function below examines the code pointed at by PC and checks to
  84    see if it corresponds to a call to __gccmain.  If so, it returns
  85    the address of the instruction following that call.  Otherwise, it
  86    simply returns PC.  */
  87
  88 static CORE_ADDR
  89 arm_wince_skip_main_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
  90 {
  91   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  92   ULONGEST this_instr;
  93
  94   this_instr = read_memory_unsigned_integer (pc, 4, byte_order);
  95
  96   /* bl offset <__gccmain> */
  97   if ((this_instr & 0xfff00000) == 0xeb000000)
  98     {
  99 #define sign_extend(V, N) \
 100   (((long) (V) ^ (1L << ((N) - 1))) - (1L << ((N) - 1)))
 101
 102       long offset = sign_extend (this_instr & 0x000fffff, 23) << 2;
 103       CORE_ADDR call_dest = (pc + 8 + offset) & 0xffffffffU;
 104       struct bound_minimal_symbol s = lookup_minimal_symbol_by_pc (call_dest);
 105
 106       if (s.minsym != NULL
 107           && s.minsym->linkage_name () != NULL
 108           && strcmp (s.minsym->linkage_name (), "__gccmain") == 0)
 109         pc += 4;
 110     }
 111
 112   return pc;
 113 }
 114
 115 static void
 116 arm_wince_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 117 {
 118   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 119
 120   windows_init_abi (info, gdbarch);
 121
 122   tdep->arm_breakpoint = arm_wince_le_breakpoint;
 123   tdep->arm_breakpoint_size = sizeof (arm_wince_le_breakpoint);
 124   tdep->thumb_breakpoint = arm_wince_thumb_le_breakpoint;
 125   tdep->thumb_breakpoint_size = sizeof (arm_wince_thumb_le_breakpoint);
 126   tdep->struct_return = pcc_struct_return;
 127
 128   tdep->fp_model = ARM_FLOAT_SOFT_VFP;
 129
 130   tdep->jb_pc = ARM_WINCE_JB_PC;
 131   tdep->jb_elt_size = ARM_WINCE_JB_ELEMENT_SIZE;
 132
 133   /* On ARM WinCE char defaults to signed.  */
 134   set_gdbarch_char_signed (gdbarch, 1);
 135
 136   /* Shared library handling.  */
 137   set_gdbarch_skip_trampoline_code (gdbarch, arm_pe_skip_trampoline_code);
 138
 139   /* Single stepping.  */
 140   set_gdbarch_software_single_step (gdbarch, arm_software_single_step);
 141
 142   /* Skip call to __gccmain that gcc places in main.  */
 143   set_gdbarch_skip_main_prologue (gdbarch, arm_wince_skip_main_prologue);
 144 }
 145
 146 static enum gdb_osabi
 147 arm_wince_osabi_sniffer (bfd *abfd)
 148 {
 149   const char *target_name = bfd_get_target (abfd);
 150
 151   if (strcmp (target_name, "pei-arm-wince-little") == 0)
 152     return GDB_OSABI_WINCE;
 153
 154   return GDB_OSABI_UNKNOWN;
 155 }
 156
 157 void _initialize_arm_wince_tdep ();
 158 void
 159 _initialize_arm_wince_tdep ()
 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 }