gdb/arm-wince-tdep.c

   1 /* Target-dependent code for Windows CE running on ARM processors,
   2    for GDB.
   3
   4    Copyright (C) 2007-2014 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        ldr  ip, [pc]
  49        ldr  pc, [ip]
  50        .dw __imp_<func>  */
  51
  52   if (pc == 0
  53       || read_memory_unsigned_integer (pc + 0, 4, byte_order) != 0xe59fc000
  54       || read_memory_unsigned_integer (pc + 4, 4, byte_order) != 0xe59cf000)
  55     return 0;
  56
  57   indirect = read_memory_unsigned_integer (pc + 8, 4, byte_order);
  58   if (indirect == 0)
  59     return 0;
  60
  61   indsym = lookup_minimal_symbol_by_pc (indirect);
  62   if (indsym.minsym == NULL)
  63     return 0;
  64
  65   symname = MSYMBOL_LINKAGE_NAME (indsym.minsym);
  66   if (symname == NULL || strncmp (symname, "__imp_", 6) != 0)
  67     return 0;
  68
  69   next_pc = read_memory_unsigned_integer (indirect, 4, byte_order);
  70   if (next_pc != 0)
  71     return next_pc;
  72
  73   /* Check with the default arm gdbarch_skip_trampoline.  */
  74   return arm_skip_stub (frame, pc);
  75 }
  76
  77 /* GCC emits a call to __gccmain in the prologue of main.
  78
  79    The function below examines the code pointed at by PC and checks to
  80    see if it corresponds to a call to __gccmain.  If so, it returns
  81    the address of the instruction following that call.  Otherwise, it
  82    simply returns PC.  */
  83
  84 static CORE_ADDR
  85 arm_wince_skip_main_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
  86 {
  87   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  88   ULONGEST this_instr;
  89
  90   this_instr = read_memory_unsigned_integer (pc, 4, byte_order);
  91
  92   /* bl offset <__gccmain> */
  93   if ((this_instr & 0xfff00000) == 0xeb000000)
  94     {
  95 #define sign_extend(V, N) \
  96   (((long) (V) ^ (1L << ((N) - 1))) - (1L << ((N) - 1)))
  97
  98       long offset = sign_extend (this_instr & 0x000fffff, 23) << 2;
  99       CORE_ADDR call_dest = (pc + 8 + offset) & 0xffffffffU;
 100       struct bound_minimal_symbol s = lookup_minimal_symbol_by_pc (call_dest);
 101
 102       if (s.minsym != NULL
 103           && MSYMBOL_LINKAGE_NAME (s.minsym) != NULL
 104           && strcmp (MSYMBOL_LINKAGE_NAME (s.minsym), "__gccmain") == 0)
 105         pc += 4;
 106     }
 107
 108   return pc;
 109 }
 110
 111 static void
 112 arm_wince_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 113 {
 114   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 115
 116   windows_init_abi (info, gdbarch);
 117
 118   tdep->arm_breakpoint = arm_wince_le_breakpoint;
 119   tdep->arm_breakpoint_size = sizeof (arm_wince_le_breakpoint);
 120   tdep->thumb_breakpoint = arm_wince_thumb_le_breakpoint;
 121   tdep->thumb_breakpoint_size = sizeof (arm_wince_thumb_le_breakpoint);
 122   tdep->struct_return = pcc_struct_return;
 123
 124   tdep->fp_model = ARM_FLOAT_SOFT_VFP;
 125
 126   tdep->jb_pc = ARM_WINCE_JB_PC;
 127   tdep->jb_elt_size = ARM_WINCE_JB_ELEMENT_SIZE;
 128
 129   /* On ARM WinCE char defaults to signed.  */
 130   set_gdbarch_char_signed (gdbarch, 1);
 131
 132   /* Shared library handling.  */
 133   set_gdbarch_skip_trampoline_code (gdbarch, arm_pe_skip_trampoline_code);
 134
 135   /* Single stepping.  */
 136   set_gdbarch_software_single_step (gdbarch, arm_software_single_step);
 137
 138   /* Skip call to __gccmain that gcc places in main.  */
 139   set_gdbarch_skip_main_prologue (gdbarch, arm_wince_skip_main_prologue);
 140 }
 141
 142 static enum gdb_osabi
 143 arm_wince_osabi_sniffer (bfd *abfd)
 144 {
 145   const char *target_name = bfd_get_target (abfd);
 146
 147   if (strcmp (target_name, "pei-arm-wince-little") == 0)
 148     return GDB_OSABI_WINCE;
 149
 150   return GDB_OSABI_UNKNOWN;
 151 }
 152
 153 /* Provide a prototype to silence -Wmissing-prototypes.  */
 154 void _initialize_arm_wince_tdep (void);
 155
 156 void
 157 _initialize_arm_wince_tdep (void)
 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 }