gdb/i386-darwin-tdep.c

   1 /* Darwin support for GDB, the GNU debugger.
   2    Copyright (C) 1997-2020 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 "symtab.h"
  27 #include "regcache.h"
  28 #include "objfiles.h"
  29
  30 #include "i387-tdep.h"
  31 #include "i386-tdep.h"
  32 #include "osabi.h"
  33 #include "ui-out.h"
  34 #include "i386-darwin-tdep.h"
  35 #include "solib.h"
  36 #include "solib-darwin.h"
  37 #include "dwarf2/frame.h"
  38 #include <algorithm>
  39
  40 /* Offsets into the struct i386_thread_state where we'll find the saved regs.
  41    From <mach/i386/thread_status.h> and i386-tdep.h.  */
  42 int i386_darwin_thread_state_reg_offset[] =
  43 {
  44    0 * 4,   /* EAX */
  45    2 * 4,   /* ECX */
  46    3 * 4,   /* EDX */
  47    1 * 4,   /* EBX */
  48    7 * 4,   /* ESP */
  49    6 * 4,   /* EBP */
  50    5 * 4,   /* ESI */
  51    4 * 4,   /* EDI */
  52   10 * 4,   /* EIP */
  53    9 * 4,   /* EFLAGS */
  54   11 * 4,   /* CS */
  55    8 * 4,   /* SS */
  56   12 * 4,   /* DS */
  57   13 * 4,   /* ES */
  58   14 * 4,   /* FS */
  59   15 * 4    /* GS */
  60 };
  61
  62 const int i386_darwin_thread_state_num_regs =
  63   ARRAY_SIZE (i386_darwin_thread_state_reg_offset);
  64
  65 /* Assuming THIS_FRAME is a Darwin sigtramp routine, return the
  66    address of the associated sigcontext structure.  */
  67
  68 static CORE_ADDR
  69 i386_darwin_sigcontext_addr (struct frame_info *this_frame)
  70 {
  71   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  72   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  73   CORE_ADDR bp;
  74   CORE_ADDR si;
  75   gdb_byte buf[4];
  76
  77   get_frame_register (this_frame, I386_EBP_REGNUM, buf);
  78   bp = extract_unsigned_integer (buf, 4, byte_order);
  79
  80   /* A pointer to the ucontext is passed as the fourth argument
  81      to the signal handler.  */
  82   read_memory (bp + 24, buf, 4);
  83   si = extract_unsigned_integer (buf, 4, byte_order);
  84
  85   /* The pointer to mcontext is at offset 28.  */
  86   read_memory (si + 28, buf, 4);
  87
  88   /* First register (eax) is at offset 12.  */
  89   return extract_unsigned_integer (buf, 4, byte_order) + 12;
  90 }
  91
  92 /* Return true if the PC of THIS_FRAME is in a signal trampoline which
  93    may have DWARF-2 CFI.
  94
  95    On Darwin, signal trampolines have DWARF-2 CFI but it has only one FDE
  96    that covers only the indirect call to the user handler.
  97    Without this function, the frame is recognized as a normal frame which is
  98    not expected.  */
  99
 100 int
 101 darwin_dwarf_signal_frame_p (struct gdbarch *gdbarch,
 102                              struct frame_info *this_frame)
 103 {
 104   return i386_sigtramp_p (this_frame);
 105 }
 106
 107 /* Check whether TYPE is a 128-bit vector (__m128, __m128d or __m128i).  */
 108
 109 static int
 110 i386_m128_p (struct type *type)
 111 {
 112   return (type->code () == TYPE_CODE_ARRAY && TYPE_VECTOR (type)
 113           && TYPE_LENGTH (type) == 16);
 114 }
 115
 116 /* Return the alignment for TYPE when passed as an argument.  */
 117
 118 static int
 119 i386_darwin_arg_type_alignment (struct type *type)
 120 {
 121   type = check_typedef (type);
 122   /* According to Mac OS X ABI document (passing arguments):
 123      6.  The caller places 64-bit vectors (__m64) on the parameter area,
 124          aligned to 8-byte boundaries.
 125      7.  [...]  The caller aligns 128-bit vectors in the parameter area to
 126          16-byte boundaries.  */
 127   if (type->code () == TYPE_CODE_ARRAY && TYPE_VECTOR (type))
 128     return TYPE_LENGTH (type);
 129   /* 4.  The caller places all the fields of structures (or unions) with no
 130          vector elements in the parameter area.  These structures are 4-byte
 131          aligned.
 132      5.  The caller places structures with vector elements on the stack,
 133          16-byte aligned.  */
 134   if (type->code () == TYPE_CODE_STRUCT
 135       || type->code () == TYPE_CODE_UNION)
 136     {
 137       int i;
 138       int res = 4;
 139       for (i = 0; i < type->num_fields (); i++)
 140         {
 141           int align
 142             = i386_darwin_arg_type_alignment (TYPE_FIELD_TYPE (type, i));
 143
 144           res = std::max (res, align);
 145         }
 146       return res;
 147     }
 148   /* 2.  The caller aligns nonvector arguments to 4-byte boundaries.  */
 149   return 4;
 150 }
 151
 152 static CORE_ADDR
 153 i386_darwin_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
 154                              struct regcache *regcache, CORE_ADDR bp_addr,
 155                              int nargs, struct value **args, CORE_ADDR sp,
 156                              function_call_return_method return_method,
 157                              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 (return_method == return_method_struct)
 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 (I387_MM0_REGNUM(tdep) + num_m128, val);
 194                 }
 195               num_m128++;
 196             }
 197           else
 198             {
 199               args_space = align_up (args_space,
 200                                      i386_darwin_arg_type_alignment (arg_type));
 201               if (write_pass)
 202                 write_memory (sp + args_space,
 203                               value_contents_all (args[i]),
 204                               TYPE_LENGTH (arg_type));
 205
 206               /* The System V ABI says that:
 207
 208                  "An argument's size is increased, if necessary, to make it a
 209                  multiple of [32-bit] words.  This may require tail padding,
 210                  depending on the size of the argument."
 211
 212                  This makes sure the stack stays word-aligned.  */
 213               args_space += align_up (TYPE_LENGTH (arg_type), 4);
 214             }
 215         }
 216
 217       /* Darwin i386 ABI:
 218          1.  The caller ensures that the stack is 16-byte aligned at the point
 219              of the function call.  */
 220       if (!write_pass)
 221         sp = align_down (sp - args_space, 16);
 222     }
 223
 224   /* Store return address.  */
 225   sp -= 4;
 226   store_unsigned_integer (buf, 4, byte_order, bp_addr);
 227   write_memory (sp, buf, 4);
 228
 229   /* Finally, update the stack pointer...  */
 230   store_unsigned_integer (buf, 4, byte_order, sp);
 231   regcache->cooked_write (I386_ESP_REGNUM, buf);
 232
 233   /* ...and fake a frame pointer.  */
 234   regcache->cooked_write (I386_EBP_REGNUM, buf);
 235
 236   /* MarkK wrote: This "+ 8" is all over the place:
 237      (i386_frame_this_id, i386_sigtramp_frame_this_id,
 238      i386_dummy_id).  It's there, since all frame unwinders for
 239      a given target have to agree (within a certain margin) on the
 240      definition of the stack address of a frame.  Otherwise frame id
 241      comparison might not work correctly.  Since DWARF2/GCC uses the
 242      stack address *before* the function call as a frame's CFA.  On
 243      the i386, when %ebp is used as a frame pointer, the offset
 244      between the contents %ebp and the CFA as defined by GCC.  */
 245   return sp + 8;
 246 }
 247
 248 static void
 249 i386_darwin_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 250 {
 251   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 252
 253   /* We support the SSE registers.  */
 254   tdep->num_xmm_regs = I386_NUM_XREGS - 1;
 255   set_gdbarch_num_regs (gdbarch, I386_SSE_NUM_REGS);
 256
 257   dwarf2_frame_set_signal_frame_p (gdbarch, darwin_dwarf_signal_frame_p);
 258   set_gdbarch_push_dummy_call (gdbarch, i386_darwin_push_dummy_call);
 259
 260   tdep->struct_return = reg_struct_return;
 261
 262   tdep->sigtramp_p = i386_sigtramp_p;
 263   tdep->sigcontext_addr = i386_darwin_sigcontext_addr;
 264   tdep->sc_reg_offset = i386_darwin_thread_state_reg_offset;
 265   tdep->sc_num_regs = i386_darwin_thread_state_num_regs;
 266
 267   tdep->jb_pc_offset = 48;
 268
 269   /* Although the i387 extended floating-point has only 80 significant
 270      bits, a `long double' actually takes up 128, probably to enforce
 271      alignment.  */
 272   set_gdbarch_long_double_bit (gdbarch, 128);
 273
 274   set_solib_ops (gdbarch, &darwin_so_ops);
 275 }
 276
 277 static enum gdb_osabi
 278 i386_mach_o_osabi_sniffer (bfd *abfd)
 279 {
 280   if (!bfd_check_format (abfd, bfd_object))
 281     return GDB_OSABI_UNKNOWN;
 282
 283   if (bfd_get_arch (abfd) == bfd_arch_i386)
 284     return GDB_OSABI_DARWIN;
 285
 286   return GDB_OSABI_UNKNOWN;
 287 }
 288
 289 void _initialize_i386_darwin_tdep ();
 290 void
 291 _initialize_i386_darwin_tdep ()
 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 }