gdb/i386-darwin-tdep.c

   1 /* Darwin support for GDB, the GNU debugger.
   2    Copyright 1997, 1998, 1999, 2000, 2001, 2002, 2005, 2008, 2009
   3    Free Software Foundation, Inc.
   4
   5    Contributed by Apple Computer, Inc.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  21
  22 #include "defs.h"
  23 #include "frame.h"
  24 #include "inferior.h"
  25 #include "gdbcore.h"
  26 #include "target.h"
  27 #include "floatformat.h"
  28 #include "symtab.h"
  29 #include "regcache.h"
  30 #include "libbfd.h"
  31 #include "objfiles.h"
  32
  33 #include "i387-tdep.h"
  34 #include "i386-tdep.h"
  35 #include "osabi.h"
  36 #include "ui-out.h"
  37 #include "symtab.h"
  38 #include "frame.h"
  39 #include "gdb_assert.h"
  40 #include "i386-darwin-tdep.h"
  41 #include "solib.h"
  42 #include "solib-darwin.h"
  43 #include "dwarf2-frame.h"
  44
  45 /* Offsets into the struct i386_thread_state where we'll find the saved regs.
  46    From <mach/i386/thread_status.h> and i386-tdep.h.  */
  47 int i386_darwin_thread_state_reg_offset[] =
  48 {
  49    0 * 4,   /* EAX */
  50    2 * 4,   /* ECX */
  51    3 * 4,   /* EDX */
  52    1 * 4,   /* EBX */
  53    7 * 4,   /* ESP */
  54    6 * 4,   /* EBP */
  55    5 * 4,   /* ESI */
  56    4 * 4,   /* EDI */
  57   10 * 4,   /* EIP */
  58    9 * 4,   /* EFLAGS */
  59   11 * 4,   /* CS */
  60    8,       /* SS */
  61   12 * 4,   /* DS */
  62   13 * 4,   /* ES */
  63   14 * 4,   /* FS */
  64   15 * 4    /* GS */
  65 };
  66
  67 const int i386_darwin_thread_state_num_regs =
  68   ARRAY_SIZE (i386_darwin_thread_state_reg_offset);
  69
  70 /* Assuming THIS_FRAME is a Darwin sigtramp routine, return the
  71    address of the associated sigcontext structure.  */
  72
  73 static CORE_ADDR
  74 i386_darwin_sigcontext_addr (struct frame_info *this_frame)
  75 {
  76   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  77   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  78   CORE_ADDR bp;
  79   CORE_ADDR si;
  80   gdb_byte buf[4];
  81
  82   get_frame_register (this_frame, I386_EBP_REGNUM, buf);
  83   bp = extract_unsigned_integer (buf, 4, byte_order);
  84
  85   /* A pointer to the ucontext is passed as the fourth argument
  86      to the signal handler.  */
  87   read_memory (bp + 24, buf, 4);
  88   si = extract_unsigned_integer (buf, 4, byte_order);
  89
  90   /* The pointer to mcontext is at offset 28.  */
  91   read_memory (si + 28, buf, 4);
  92
  93   /* First register (eax) is at offset 12.  */
  94   return extract_unsigned_integer (buf, 4, byte_order) + 12;
  95 }
  96
  97 /* Return true if the PC of THIS_FRAME is in a signal trampoline which
  98    may have DWARF-2 CFI.
  99
 100    On Darwin, signal trampolines have DWARF-2 CFI but it has only one FDE
 101    that covers only the indirect call to the user handler.
 102    Without this function, the frame is recognized as a normal frame which is
 103    not expected.  */
 104
 105 int
 106 darwin_dwarf_signal_frame_p (struct gdbarch *gdbarch,
 107                              struct frame_info *this_frame)
 108 {
 109   return i386_sigtramp_p (this_frame);
 110 }
 111
 112 /* Check wether TYPE is a 128-bit vector (__m128, __m128d or __m128i).  */
 113
 114 static int
 115 i386_m128_p (struct type *type)
 116 {
 117   return (TYPE_CODE (type) == TYPE_CODE_ARRAY && TYPE_VECTOR (type)
 118           && TYPE_LENGTH (type) == 16);
 119 }
 120
 121 /* Return the alignment for TYPE when passed as an argument.  */
 122
 123 static int
 124 i386_darwin_arg_type_alignment (struct type *type)
 125 {
 126   type = check_typedef (type);
 127   /* According to Mac OS X ABI document (passing arguments):
 128      6.  The caller places 64-bit vectors (__m64) on the parameter area,
 129          aligned to 8-byte boundaries.
 130      7.  [...]  The caller aligns 128-bit vectors in the parameter area to
 131          16-byte boundaries.  */
 132   if (TYPE_CODE (type) == TYPE_CODE_ARRAY && TYPE_VECTOR (type))
 133     return TYPE_LENGTH (type);
 134   /* 4.  The caller places all the fields of structures (or unions) with no
 135          vector elements in the parameter area.  These structures are 4-byte
 136          aligned.
 137      5.  The caller places structures with vector elements on the stack,
 138          16-byte aligned.  */
 139   if (TYPE_CODE (type) == TYPE_CODE_STRUCT
 140       || TYPE_CODE (type) == TYPE_CODE_UNION)
 141     {
 142       int i;
 143       int res = 4;
 144       for (i = 0; i < TYPE_NFIELDS (type); i++)
 145         res = max (res,
 146                    i386_darwin_arg_type_alignment (TYPE_FIELD_TYPE (type, i)));
 147       return res;
 148     }
 149   /* 2.  The caller aligns nonvector arguments to 4-byte boundaries.  */
 150   return 4;
 151 }
 152
 153 static CORE_ADDR
 154 i386_darwin_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
 155                              struct regcache *regcache, CORE_ADDR bp_addr,
 156                              int nargs, struct value **args, CORE_ADDR sp,
 157                              int struct_return, CORE_ADDR struct_addr)
 158 {
 159   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 160   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 161   gdb_byte buf[4];
 162   int i;
 163   int write_pass;
 164
 165   /* Determine the total space required for arguments and struct
 166      return address in a first pass, then push arguments in a second pass.  */
 167
 168   for (write_pass = 0; write_pass < 2; write_pass++)
 169     {
 170       int args_space = 0;
 171       int num_m128 = 0;
 172
 173       if (struct_return)
 174         {
 175           if (write_pass)
 176             {
 177               /* Push value address.  */
 178               store_unsigned_integer (buf, 4, byte_order, struct_addr);
 179               write_memory (sp, buf, 4);
 180             }
 181           args_space += 4;
 182         }
 183
 184       for (i = 0; i < nargs; i++)
 185         {
 186           struct type *arg_type = value_enclosing_type (args[i]);
 187
 188           if (i386_m128_p (arg_type) && num_m128 < 4)
 189             {
 190               if (write_pass)
 191                 {
 192                   const gdb_byte *val = value_contents_all (args[i]);
 193                   regcache_raw_write
 194                     (regcache, I387_MM0_REGNUM(tdep) + num_m128, val);
 195                 }
 196               num_m128++;
 197             }
 198           else
 199             {
 200               int len = TYPE_LENGTH (arg_type);
 201               int align = i386_darwin_arg_type_alignment (arg_type);
 202
 203               args_space = align_up (args_space, align);
 204               if (write_pass)
 205                 write_memory (sp + args_space,
 206                               value_contents_all (args[i]), len);
 207
 208               /* The System V ABI says that:
 209
 210                  "An argument's size is increased, if necessary, to make it a
 211                  multiple of [32-bit] words.  This may require tail padding,
 212                  depending on the size of the argument."
 213
 214                  This makes sure the stack stays word-aligned.  */
 215               args_space += align_up (len, 4);
 216             }
 217         }
 218
 219       /* Darwin i386 ABI:
 220          1.  The caller ensures that the stack is 16-byte aligned at the point
 221              of the function call.  */
 222       if (!write_pass)
 223         sp = align_down (sp - args_space, 16);
 224     }
 225
 226   /* Store return address.  */
 227   sp -= 4;
 228   store_unsigned_integer (buf, 4, byte_order, bp_addr);
 229   write_memory (sp, buf, 4);
 230
 231   /* Finally, update the stack pointer...  */
 232   store_unsigned_integer (buf, 4, byte_order, sp);
 233   regcache_cooked_write (regcache, I386_ESP_REGNUM, buf);
 234
 235   /* ...and fake a frame pointer.  */
 236   regcache_cooked_write (regcache, I386_EBP_REGNUM, buf);
 237
 238   /* MarkK wrote: This "+ 8" is all over the place:
 239      (i386_frame_this_id, i386_sigtramp_frame_this_id,
 240      i386_dummy_id).  It's there, since all frame unwinders for
 241      a given target have to agree (within a certain margin) on the
 242      definition of the stack address of a frame.  Otherwise frame id
 243      comparison might not work correctly.  Since DWARF2/GCC uses the
 244      stack address *before* the function call as a frame's CFA.  On
 245      the i386, when %ebp is used as a frame pointer, the offset
 246      between the contents %ebp and the CFA as defined by GCC.  */
 247   return sp + 8;
 248 }
 249
 250 static void
 251 i386_darwin_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 252 {
 253   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 254
 255   /* We support the SSE registers.  */
 256   tdep->num_xmm_regs = I386_NUM_XREGS - 1;
 257   set_gdbarch_num_regs (gdbarch, I386_SSE_NUM_REGS);
 258
 259   dwarf2_frame_set_signal_frame_p (gdbarch, darwin_dwarf_signal_frame_p);
 260   set_gdbarch_push_dummy_call (gdbarch, i386_darwin_push_dummy_call);
 261
 262   tdep->struct_return = reg_struct_return;
 263
 264   tdep->sigtramp_p = i386_sigtramp_p;
 265   tdep->sigcontext_addr = i386_darwin_sigcontext_addr;
 266   tdep->sc_reg_offset = i386_darwin_thread_state_reg_offset;
 267   tdep->sc_num_regs = i386_darwin_thread_state_num_regs;
 268
 269   tdep->jb_pc_offset = 48;
 270
 271   /* Although the i387 extended floating-point has only 80 significant
 272      bits, a `long double' actually takes up 128, probably to enforce
 273      alignment.  */
 274   set_gdbarch_long_double_bit (gdbarch, 128);
 275
 276   set_solib_ops (gdbarch, &darwin_so_ops);
 277 }
 278
 279 static enum gdb_osabi
 280 i386_mach_o_osabi_sniffer (bfd *abfd)
 281 {
 282   if (!bfd_check_format (abfd, bfd_object))
 283     return GDB_OSABI_UNKNOWN;
 284
 285   if (bfd_get_arch (abfd) == bfd_arch_i386)
 286     return GDB_OSABI_DARWIN;
 287
 288   return GDB_OSABI_UNKNOWN;
 289 }
 290
 291 void
 292 _initialize_i386_darwin_tdep (void)
 293 {
 294   gdbarch_register_osabi_sniffer (bfd_arch_unknown, bfd_target_mach_o_flavour,
 295                                   i386_mach_o_osabi_sniffer);
 296
 297   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_i386_i386,
 298                           GDB_OSABI_DARWIN, i386_darwin_init_abi);
 299 }