gdb/arm-wince-tdep.c

   1 /* Target-dependent code for Windows CE running on ARM processors,
   2    for GDB.
   3
   4    Copyright (C) 2007-2024 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 "osabi.h"
  22 #include "gdbcore.h"
  23 #include "target.h"
  24 #include "frame.h"
  25
  26 #include "arch/arm.h"
  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       ARM_INT_REGISTER_SIZE
  35 #define ARM_WINCE_JB_PC                 10
  36
  37 static CORE_ADDR
  38 arm_pe_skip_trampoline_code (const frame_info_ptr &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   const char *symname;
  44   CORE_ADDR next_pc;
  45
  46   /* The format of an ARM DLL trampoline is:
  47
  48        ldr  ip, [pc]
  49        ldr  pc, [ip]
  50        .dw __imp_<func>
  51
  52   */
  53
  54   if (pc == 0
  55       || read_memory_unsigned_integer (pc + 0, 4, byte_order) != 0xe59fc000
  56       || read_memory_unsigned_integer (pc + 4, 4, byte_order) != 0xe59cf000)
  57     return 0;
  58
  59   indirect = read_memory_unsigned_integer (pc + 8, 4, byte_order);
  60   if (indirect == 0)
  61     return 0;
  62
  63   bound_minimal_symbol indsym = lookup_minimal_symbol_by_pc (indirect);
  64   if (indsym.minsym == NULL)
  65     return 0;
  66
  67   symname = indsym.minsym->linkage_name ();
  68   if (symname == NULL || !startswith (symname, "__imp_"))
  69     return 0;
  70
  71   next_pc = read_memory_unsigned_integer (indirect, 4, byte_order);
  72   if (next_pc != 0)
  73     return next_pc;
  74
  75   /* Check with the default arm gdbarch_skip_trampoline.  */
  76   return arm_skip_stub (frame, pc);
  77 }
  78
  79 /* GCC emits a call to __gccmain in the prologue of main.
  80
  81    The function below examines the code pointed at by PC and checks to
  82    see if it corresponds to a call to __gccmain.  If so, it returns
  83    the address of the instruction following that call.  Otherwise, it
  84    simply returns PC.  */
  85
  86 static CORE_ADDR
  87 arm_wince_skip_main_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
  88 {
  89   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  90   ULONGEST this_instr;
  91
  92   this_instr = read_memory_unsigned_integer (pc, 4, byte_order);
  93
  94   /* bl offset <__gccmain> */
  95   if ((this_instr & 0xfff00000) == 0xeb000000)
  96     {
  97 #define sign_extend(V, N) \
  98   (((long) (V) ^ (1L << ((N) - 1))) - (1L << ((N) - 1)))
  99
 100       long offset = sign_extend (this_instr & 0x000fffff, 23) << 2;
 101       CORE_ADDR call_dest = (pc + 8 + offset) & 0xffffffffU;
 102       bound_minimal_symbol s = lookup_minimal_symbol_by_pc (call_dest);
 103
 104       if (s.minsym != NULL
 105           && s.minsym->linkage_name () != NULL
 106           && strcmp (s.minsym->linkage_name (), "__gccmain") == 0)
 107         pc += 4;
 108     }
 109
 110   return pc;
 111 }
 112
 113 static void
 114 arm_wince_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 115 {
 116   arm_gdbarch_tdep *tdep = gdbarch_tdep<arm_gdbarch_tdep> (gdbarch);
 117
 118   windows_init_abi (info, gdbarch);
 119
 120   tdep->arm_breakpoint = arm_wince_le_breakpoint;
 121   tdep->arm_breakpoint_size = sizeof (arm_wince_le_breakpoint);
 122   tdep->thumb_breakpoint = arm_wince_thumb_le_breakpoint;
 123   tdep->thumb_breakpoint_size = sizeof (arm_wince_thumb_le_breakpoint);
 124   tdep->struct_return = pcc_struct_return;
 125
 126   tdep->fp_model = ARM_FLOAT_SOFT_VFP;
 127
 128   tdep->jb_pc = ARM_WINCE_JB_PC;
 129   tdep->jb_elt_size = ARM_WINCE_JB_ELEMENT_SIZE;
 130
 131   /* On ARM WinCE char defaults to signed.  */
 132   set_gdbarch_char_signed (gdbarch, 1);
 133
 134   /* Shared library handling.  */
 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 void _initialize_arm_wince_tdep ();
 156 void
 157 _initialize_arm_wince_tdep ()
 158 {
 159   gdbarch_register_osabi_sniffer (bfd_arch_arm, bfd_target_coff_flavour,
 160                                   arm_wince_osabi_sniffer);
 161
 162   gdbarch_register_osabi (bfd_arch_arm, 0, GDB_OSABI_WINCE,
 163                           arm_wince_init_abi);
 164 }