gdb/i386-darwin-tdep.c

   1 /* Darwin support for GDB, the GNU debugger.
   2    Copyright (C) 1997-2017 Free Software Foundation, Inc.
   3
   4    Contributed by Apple Computer, 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 "frame.h"
  23 #include "inferior.h"
  24 #include "gdbcore.h"
  25 #include "target.h"
  26 #include "floatformat.h"
  27 #include "symtab.h"
  28 #include "regcache.h"
  29 #include "objfiles.h"
  30
  31 #include "i387-tdep.h"
  32 #include "i386-tdep.h"
  33 #include "osabi.h"
  34 #include "ui-out.h"
  35 #include "i386-darwin-tdep.h"
  36 #include "solib.h"
  37 #include "solib-darwin.h"
  38 #include "dwarf2-frame.h"
  39 #include <algorithm>
  40
  41 /* Offsets into the struct i386_thread_state where we'll find the saved regs.
  42    From <mach/i386/thread_status.h> and i386-tdep.h.  */
  43 int i386_darwin_thread_state_reg_offset[] =
  44 {
  45    0 * 4,   /* EAX */
  46    2 * 4,   /* ECX */
  47    3 * 4,   /* EDX */
  48    1 * 4,   /* EBX */
  49    7 * 4,   /* ESP */
  50    6 * 4,   /* EBP */
  51    5 * 4,   /* ESI */
  52    4 * 4,   /* EDI */
  53   10 * 4,   /* EIP */
  54    9 * 4,   /* EFLAGS */
  55   11 * 4,   /* CS */
  56    8 * 4,   /* SS */
  57   12 * 4,   /* DS */
  58   13 * 4,   /* ES */
  59   14 * 4,   /* FS */
  60   15 * 4    /* GS */
  61 };
  62
  63 const int i386_darwin_thread_state_num_regs =
  64   ARRAY_SIZE (i386_darwin_thread_state_reg_offset);
  65
  66 /* Assuming THIS_FRAME is a Darwin sigtramp routine, return the
  67    address of the associated sigcontext structure.  */
  68
  69 static CORE_ADDR
  70 i386_darwin_sigcontext_addr (struct frame_info *this_frame)
  71 {
  72   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  73   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  74   CORE_ADDR bp;
  75   CORE_ADDR si;
  76   gdb_byte buf[4];
  77
  78   get_frame_register (this_frame, I386_EBP_REGNUM, buf);
  79   bp = extract_unsigned_integer (buf, 4, byte_order);
  80
  81   /* A pointer to the ucontext is passed as the fourth argument
  82      to the signal handler.  */
  83   read_memory (bp + 24, buf, 4);
  84   si = extract_unsigned_integer (buf, 4, byte_order);
  85
  86   /* The pointer to mcontext is at offset 28.  */
  87   read_memory (si + 28, buf, 4);
  88
  89   /* First register (eax) is at offset 12.  */
  90   return extract_unsigned_integer (buf, 4, byte_order) + 12;
  91 }
  92
  93 /* Return true if the PC of THIS_FRAME is in a signal trampoline which
  94    may have DWARF-2 CFI.
  95
  96    On Darwin, signal trampolines have DWARF-2 CFI but it has only one FDE
  97    that covers only the indirect call to the user handler.
  98    Without this function, the frame is recognized as a normal frame which is
  99    not expected.  */
 100
 101 int
 102 darwin_dwarf_signal_frame_p (struct gdbarch *gdbarch,
 103                              struct frame_info *this_frame)
 104 {
 105   return i386_sigtramp_p (this_frame);
 106 }
 107
 108 /* Check wether TYPE is a 128-bit vector (__m128, __m128d or __m128i).  */
 109
 110 static int
 111 i386_m128_p (struct type *type)
 112 {
 113   return (TYPE_CODE (type) == TYPE_CODE_ARRAY && TYPE_VECTOR (type)
 114           && TYPE_LENGTH (type) == 16);
 115 }
 116
 117 /* Return the alignment for TYPE when passed as an argument.  */
 118
 119 static int
 120 i386_darwin_arg_type_alignment (struct type *type)
 121 {
 122   type = check_typedef (type);
 123   /* According to Mac OS X ABI document (passing arguments):
 124      6.  The caller places 64-bit vectors (__m64) on the parameter area,
 125          aligned to 8-byte boundaries.
 126      7.  [...]  The caller aligns 128-bit vectors in the parameter area to
 127          16-byte boundaries.  */
 128   if (TYPE_CODE (type) == TYPE_CODE_ARRAY && TYPE_VECTOR (type))
 129     return TYPE_LENGTH (type);
 130   /* 4.  The caller places all the fields of structures (or unions) with no
 131          vector elements in the parameter area.  These structures are 4-byte
 132          aligned.
 133      5.  The caller places structures with vector elements on the stack,
 134          16-byte aligned.  */
 135   if (TYPE_CODE (type) == TYPE_CODE_STRUCT
 136       || TYPE_CODE (type) == TYPE_CODE_UNION)
 137     {
 138       int i;
 139       int res = 4;
 140       for (i = 0; i < TYPE_NFIELDS (type); i++)
 141         {
 142           int align
 143             = i386_darwin_arg_type_alignment (TYPE_FIELD_TYPE (type, i));
 144
 145           res = std::max (res, align);
 146         }
 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               args_space = align_up (args_space,
 201                                      i386_darwin_arg_type_alignment (arg_type));
 202               if (write_pass)
 203                 write_memory (sp + args_space,
 204                               value_contents_all (args[i]),
 205                               TYPE_LENGTH (arg_type));
 206
 207               /* The System V ABI says that:
 208
 209                  "An argument's size is increased, if necessary, to make it a
 210                  multiple of [32-bit] words.  This may require tail padding,
 211                  depending on the size of the argument."
 212
 213                  This makes sure the stack stays word-aligned.  */
 214               args_space += align_up (TYPE_LENGTH (arg_type), 4);
 215             }
 216         }
 217
 218       /* Darwin i386 ABI:
 219          1.  The caller ensures that the stack is 16-byte aligned at the point
 220              of the function call.  */
 221       if (!write_pass)
 222         sp = align_down (sp - args_space, 16);
 223     }
 224
 225   /* Store return address.  */
 226   sp -= 4;
 227   store_unsigned_integer (buf, 4, byte_order, bp_addr);
 228   write_memory (sp, buf, 4);
 229
 230   /* Finally, update the stack pointer...  */
 231   store_unsigned_integer (buf, 4, byte_order, sp);
 232   regcache_cooked_write (regcache, I386_ESP_REGNUM, buf);
 233
 234   /* ...and fake a frame pointer.  */
 235   regcache_cooked_write (regcache, I386_EBP_REGNUM, buf);
 236
 237   /* MarkK wrote: This "+ 8" is all over the place:
 238      (i386_frame_this_id, i386_sigtramp_frame_this_id,
 239      i386_dummy_id).  It's there, since all frame unwinders for
 240      a given target have to agree (within a certain margin) on the
 241      definition of the stack address of a frame.  Otherwise frame id
 242      comparison might not work correctly.  Since DWARF2/GCC uses the
 243      stack address *before* the function call as a frame's CFA.  On
 244      the i386, when %ebp is used as a frame pointer, the offset
 245      between the contents %ebp and the CFA as defined by GCC.  */
 246   return sp + 8;
 247 }
 248
 249 static void
 250 i386_darwin_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 251 {
 252   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 253
 254   /* We support the SSE registers.  */
 255   tdep->num_xmm_regs = I386_NUM_XREGS - 1;
 256   set_gdbarch_num_regs (gdbarch, I386_SSE_NUM_REGS);
 257
 258   dwarf2_frame_set_signal_frame_p (gdbarch, darwin_dwarf_signal_frame_p);
 259   set_gdbarch_push_dummy_call (gdbarch, i386_darwin_push_dummy_call);
 260
 261   tdep->struct_return = reg_struct_return;
 262
 263   tdep->sigtramp_p = i386_sigtramp_p;
 264   tdep->sigcontext_addr = i386_darwin_sigcontext_addr;
 265   tdep->sc_reg_offset = i386_darwin_thread_state_reg_offset;
 266   tdep->sc_num_regs = i386_darwin_thread_state_num_regs;
 267
 268   tdep->jb_pc_offset = 48;
 269
 270   /* Although the i387 extended floating-point has only 80 significant
 271      bits, a `long double' actually takes up 128, probably to enforce
 272      alignment.  */
 273   set_gdbarch_long_double_bit (gdbarch, 128);
 274
 275   set_solib_ops (gdbarch, &darwin_so_ops);
 276 }
 277
 278 static enum gdb_osabi
 279 i386_mach_o_osabi_sniffer (bfd *abfd)
 280 {
 281   if (!bfd_check_format (abfd, bfd_object))
 282     return GDB_OSABI_UNKNOWN;
 283
 284   if (bfd_get_arch (abfd) == bfd_arch_i386)
 285     return GDB_OSABI_DARWIN;
 286
 287   return GDB_OSABI_UNKNOWN;
 288 }
 289
 290 void
 291 _initialize_i386_darwin_tdep (void)
 292 {
 293   gdbarch_register_osabi_sniffer (bfd_arch_unknown, bfd_target_mach_o_flavour,
 294                                   i386_mach_o_osabi_sniffer);
 295
 296   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_i386_i386,
 297                           GDB_OSABI_DARWIN, i386_darwin_init_abi);
 298 }