gdb/i386-darwin-nat.c

   1 /* Darwin support for GDB, the GNU debugger.
   2    Copyright (C) 1997-2014 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 "target.h"
  25 #include "symfile.h"
  26 #include "symtab.h"
  27 #include "objfiles.h"
  28 #include "gdbcmd.h"
  29 #include "regcache.h"
  30 #include "gdb_assert.h"
  31 #include "i386-tdep.h"
  32 #include "i387-tdep.h"
  33 #include "gdbarch.h"
  34 #include "arch-utils.h"
  35 #include "gdbcore.h"
  36
  37 #include "i386-nat.h"
  38 #include "darwin-nat.h"
  39 #include "i386-darwin-tdep.h"
  40
  41 #ifdef BFD64
  42 #include "amd64-nat.h"
  43 #include "amd64-tdep.h"
  44 #include "amd64-darwin-tdep.h"
  45 #endif
  46
  47 /* Read register values from the inferior process.
  48    If REGNO is -1, do this for all registers.
  49    Otherwise, REGNO specifies which register (so we can save time).  */
  50 static void
  51 i386_darwin_fetch_inferior_registers (struct target_ops *ops,
  52                                       struct regcache *regcache, int regno)
  53 {
  54   thread_t current_thread = ptid_get_tid (inferior_ptid);
  55   int fetched = 0;
  56   struct gdbarch *gdbarch = get_regcache_arch (regcache);
  57
  58 #ifdef BFD64
  59   if (gdbarch_ptr_bit (gdbarch) == 64)
  60     {
  61       if (regno == -1 || amd64_native_gregset_supplies_p (gdbarch, regno))
  62         {
  63           x86_thread_state_t gp_regs;
  64           unsigned int gp_count = x86_THREAD_STATE_COUNT;
  65           kern_return_t ret;
  66
  67           ret = thread_get_state
  68             (current_thread, x86_THREAD_STATE, (thread_state_t) & gp_regs,
  69              &gp_count);
  70           if (ret != KERN_SUCCESS)
  71             {
  72               printf_unfiltered (_("Error calling thread_get_state for "
  73                                    "GP registers for thread 0x%lx\n"),
  74                                  (unsigned long) current_thread);
  75               MACH_CHECK_ERROR (ret);
  76             }
  77           amd64_supply_native_gregset (regcache, &gp_regs.uts, -1);
  78           fetched++;
  79         }
  80
  81       if (regno == -1 || !amd64_native_gregset_supplies_p (gdbarch, regno))
  82         {
  83           x86_float_state_t fp_regs;
  84           unsigned int fp_count = x86_FLOAT_STATE_COUNT;
  85           kern_return_t ret;
  86
  87           ret = thread_get_state
  88             (current_thread, x86_FLOAT_STATE, (thread_state_t) & fp_regs,
  89              &fp_count);
  90           if (ret != KERN_SUCCESS)
  91             {
  92               printf_unfiltered (_("Error calling thread_get_state for "
  93                                    "float registers for thread 0x%lx\n"),
  94                                  (unsigned long) current_thread);
  95               MACH_CHECK_ERROR (ret);
  96             }
  97           amd64_supply_fxsave (regcache, -1, &fp_regs.ufs.fs64.__fpu_fcw);
  98           fetched++;
  99         }
 100     }
 101   else
 102 #endif
 103     {
 104       if (regno == -1 || regno < I386_NUM_GREGS)
 105         {
 106           x86_thread_state32_t gp_regs;
 107           unsigned int gp_count = x86_THREAD_STATE32_COUNT;
 108           kern_return_t ret;
 109           int i;
 110
 111           ret = thread_get_state
 112             (current_thread, x86_THREAD_STATE32, (thread_state_t) &gp_regs,
 113              &gp_count);
 114           if (ret != KERN_SUCCESS)
 115             {
 116               printf_unfiltered (_("Error calling thread_get_state for "
 117                                    "GP registers for thread 0x%lx\n"),
 118                                  (unsigned long) current_thread);
 119               MACH_CHECK_ERROR (ret);
 120             }
 121           for (i = 0; i < I386_NUM_GREGS; i++)
 122             regcache_raw_supply
 123               (regcache, i,
 124                (char *)&gp_regs + i386_darwin_thread_state_reg_offset[i]);
 125
 126           fetched++;
 127         }
 128
 129       if (regno == -1
 130           || (regno >= I386_ST0_REGNUM && regno < I386_SSE_NUM_REGS))
 131         {
 132           x86_float_state32_t fp_regs;
 133           unsigned int fp_count = x86_FLOAT_STATE32_COUNT;
 134           kern_return_t ret;
 135
 136           ret = thread_get_state
 137             (current_thread, x86_FLOAT_STATE32, (thread_state_t) &fp_regs,
 138              &fp_count);
 139           if (ret != KERN_SUCCESS)
 140             {
 141               printf_unfiltered (_("Error calling thread_get_state for "
 142                                    "float registers for thread 0x%lx\n"),
 143                                  (unsigned long) current_thread);
 144               MACH_CHECK_ERROR (ret);
 145             }
 146           i387_supply_fxsave (regcache, -1, &fp_regs.__fpu_fcw);
 147           fetched++;
 148         }
 149     }
 150
 151   if (! fetched)
 152     {
 153       warning (_("unknown register %d"), regno);
 154       regcache_raw_supply (regcache, regno, NULL);
 155     }
 156 }
 157
 158 /* Store our register values back into the inferior.
 159    If REGNO is -1, do this for all registers.
 160    Otherwise, REGNO specifies which register (so we can save time).  */
 161
 162 static void
 163 i386_darwin_store_inferior_registers (struct target_ops *ops,
 164                                       struct regcache *regcache, int regno)
 165 {
 166   thread_t current_thread = ptid_get_tid (inferior_ptid);
 167   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 168
 169 #ifdef BFD64
 170   if (gdbarch_ptr_bit (gdbarch) == 64)
 171     {
 172       if (regno == -1 || amd64_native_gregset_supplies_p (gdbarch, regno))
 173         {
 174           x86_thread_state_t gp_regs;
 175           kern_return_t ret;
 176           unsigned int gp_count = x86_THREAD_STATE_COUNT;
 177
 178           ret = thread_get_state
 179             (current_thread, x86_THREAD_STATE, (thread_state_t) &gp_regs,
 180              &gp_count);
 181           MACH_CHECK_ERROR (ret);
 182           gdb_assert (gp_regs.tsh.flavor == x86_THREAD_STATE64);
 183           gdb_assert (gp_regs.tsh.count == x86_THREAD_STATE64_COUNT);
 184
 185           amd64_collect_native_gregset (regcache, &gp_regs.uts, regno);
 186
 187           ret = thread_set_state (current_thread, x86_THREAD_STATE,
 188                                   (thread_state_t) &gp_regs,
 189                                   x86_THREAD_STATE_COUNT);
 190           MACH_CHECK_ERROR (ret);
 191         }
 192
 193       if (regno == -1 || !amd64_native_gregset_supplies_p (gdbarch, regno))
 194         {
 195           x86_float_state_t fp_regs;
 196           kern_return_t ret;
 197           unsigned int fp_count = x86_FLOAT_STATE_COUNT;
 198
 199           ret = thread_get_state
 200             (current_thread, x86_FLOAT_STATE, (thread_state_t) & fp_regs,
 201              &fp_count);
 202           MACH_CHECK_ERROR (ret);
 203           gdb_assert (fp_regs.fsh.flavor == x86_FLOAT_STATE64);
 204           gdb_assert (fp_regs.fsh.count == x86_FLOAT_STATE64_COUNT);
 205
 206           amd64_collect_fxsave (regcache, regno, &fp_regs.ufs.fs64.__fpu_fcw);
 207
 208           ret = thread_set_state (current_thread, x86_FLOAT_STATE,
 209                                   (thread_state_t) & fp_regs,
 210                                   x86_FLOAT_STATE_COUNT);
 211           MACH_CHECK_ERROR (ret);
 212         }
 213     }
 214   else
 215 #endif
 216     {
 217       if (regno == -1 || regno < I386_NUM_GREGS)
 218         {
 219           x86_thread_state32_t gp_regs;
 220           kern_return_t ret;
 221           unsigned int gp_count = x86_THREAD_STATE32_COUNT;
 222           int i;
 223
 224           ret = thread_get_state
 225             (current_thread, x86_THREAD_STATE32, (thread_state_t) &gp_regs,
 226              &gp_count);
 227           MACH_CHECK_ERROR (ret);
 228
 229           for (i = 0; i < I386_NUM_GREGS; i++)
 230             if (regno == -1 || regno == i)
 231               regcache_raw_collect
 232                 (regcache, i,
 233                  (char *)&gp_regs + i386_darwin_thread_state_reg_offset[i]);
 234
 235           ret = thread_set_state (current_thread, x86_THREAD_STATE32,
 236                                   (thread_state_t) &gp_regs,
 237                                   x86_THREAD_STATE32_COUNT);
 238           MACH_CHECK_ERROR (ret);
 239         }
 240
 241       if (regno == -1
 242           || (regno >= I386_ST0_REGNUM && regno < I386_SSE_NUM_REGS))
 243         {
 244           x86_float_state32_t fp_regs;
 245           unsigned int fp_count = x86_FLOAT_STATE32_COUNT;
 246           kern_return_t ret;
 247
 248           ret = thread_get_state
 249             (current_thread, x86_FLOAT_STATE32, (thread_state_t) & fp_regs,
 250              &fp_count);
 251           MACH_CHECK_ERROR (ret);
 252
 253           i387_collect_fxsave (regcache, regno, &fp_regs.__fpu_fcw);
 254
 255           ret = thread_set_state (current_thread, x86_FLOAT_STATE32,
 256                                   (thread_state_t) &fp_regs,
 257                                   x86_FLOAT_STATE32_COUNT);
 258           MACH_CHECK_ERROR (ret);
 259         }
 260     }
 261 }
 262
 263 /* Support for debug registers, boosted mostly from i386-linux-nat.c.  */
 264
 265 static void
 266 i386_darwin_dr_set (int regnum, CORE_ADDR value)
 267 {
 268   int current_pid;
 269   thread_t current_thread;
 270   x86_debug_state_t dr_regs;
 271   kern_return_t ret;
 272   unsigned int dr_count;
 273
 274   gdb_assert (regnum >= 0 && regnum <= DR_CONTROL);
 275
 276   current_thread = ptid_get_tid (inferior_ptid);
 277
 278   dr_regs.dsh.flavor = x86_DEBUG_STATE;
 279   dr_regs.dsh.count = x86_DEBUG_STATE_COUNT;
 280   dr_count = x86_DEBUG_STATE_COUNT;
 281   ret = thread_get_state (current_thread, x86_DEBUG_STATE,
 282                           (thread_state_t) &dr_regs, &dr_count);
 283   MACH_CHECK_ERROR (ret);
 284
 285   switch (dr_regs.dsh.flavor)
 286     {
 287     case x86_DEBUG_STATE32:
 288       switch (regnum)
 289         {
 290         case 0:
 291           dr_regs.uds.ds32.__dr0 = value;
 292           break;
 293         case 1:
 294           dr_regs.uds.ds32.__dr1 = value;
 295           break;
 296         case 2:
 297           dr_regs.uds.ds32.__dr2 = value;
 298           break;
 299         case 3:
 300           dr_regs.uds.ds32.__dr3 = value;
 301           break;
 302         case 4:
 303           dr_regs.uds.ds32.__dr4 = value;
 304           break;
 305         case 5:
 306           dr_regs.uds.ds32.__dr5 = value;
 307           break;
 308         case 6:
 309           dr_regs.uds.ds32.__dr6 = value;
 310           break;
 311         case 7:
 312           dr_regs.uds.ds32.__dr7 = value;
 313           break;
 314         }
 315       break;
 316 #ifdef BFD64
 317     case x86_DEBUG_STATE64:
 318       switch (regnum)
 319         {
 320         case 0:
 321           dr_regs.uds.ds64.__dr0 = value;
 322           break;
 323         case 1:
 324           dr_regs.uds.ds64.__dr1 = value;
 325           break;
 326         case 2:
 327           dr_regs.uds.ds64.__dr2 = value;
 328           break;
 329         case 3:
 330           dr_regs.uds.ds64.__dr3 = value;
 331           break;
 332         case 4:
 333           dr_regs.uds.ds64.__dr4 = value;
 334           break;
 335         case 5:
 336           dr_regs.uds.ds64.__dr5 = value;
 337           break;
 338         case 6:
 339           dr_regs.uds.ds64.__dr6 = value;
 340           break;
 341         case 7:
 342           dr_regs.uds.ds64.__dr7 = value;
 343           break;
 344         }
 345       break;
 346 #endif
 347     }
 348
 349   ret = thread_set_state (current_thread, dr_regs.dsh.flavor,
 350                           (thread_state_t) &dr_regs.uds, dr_count);
 351
 352   MACH_CHECK_ERROR (ret);
 353 }
 354
 355 static CORE_ADDR
 356 i386_darwin_dr_get (int regnum)
 357 {
 358   thread_t current_thread;
 359   x86_debug_state_t dr_regs;
 360   kern_return_t ret;
 361   unsigned int dr_count;
 362
 363   gdb_assert (regnum >= 0 && regnum <= DR_CONTROL);
 364
 365   current_thread = ptid_get_tid (inferior_ptid);
 366
 367   dr_regs.dsh.flavor = x86_DEBUG_STATE;
 368   dr_regs.dsh.count = x86_DEBUG_STATE_COUNT;
 369   dr_count = x86_DEBUG_STATE_COUNT;
 370   ret = thread_get_state (current_thread, x86_DEBUG_STATE,
 371                           (thread_state_t) &dr_regs, &dr_count);
 372   MACH_CHECK_ERROR (ret);
 373
 374   switch (dr_regs.dsh.flavor)
 375     {
 376     case x86_DEBUG_STATE32:
 377       switch (regnum)
 378         {
 379         case 0:
 380           return dr_regs.uds.ds32.__dr0;
 381         case 1:
 382           return dr_regs.uds.ds32.__dr1;
 383         case 2:
 384           return dr_regs.uds.ds32.__dr2;
 385         case 3:
 386           return dr_regs.uds.ds32.__dr3;
 387         case 4:
 388           return dr_regs.uds.ds32.__dr4;
 389         case 5:
 390           return dr_regs.uds.ds32.__dr5;
 391         case 6:
 392           return dr_regs.uds.ds32.__dr6;
 393         case 7:
 394           return dr_regs.uds.ds32.__dr7;
 395         default:
 396           return -1;
 397         }
 398       break;
 399 #ifdef BFD64
 400     case x86_DEBUG_STATE64:
 401       switch (regnum)
 402         {
 403         case 0:
 404           return dr_regs.uds.ds64.__dr0;
 405         case 1:
 406           return dr_regs.uds.ds64.__dr1;
 407         case 2:
 408           return dr_regs.uds.ds64.__dr2;
 409         case 3:
 410           return dr_regs.uds.ds64.__dr3;
 411         case 4:
 412           return dr_regs.uds.ds64.__dr4;
 413         case 5:
 414           return dr_regs.uds.ds64.__dr5;
 415         case 6:
 416           return dr_regs.uds.ds64.__dr6;
 417         case 7:
 418           return dr_regs.uds.ds64.__dr7;
 419         default:
 420           return -1;
 421         }
 422       break;
 423 #endif
 424     default:
 425       return -1;
 426     }
 427 }
 428
 429 static void
 430 i386_darwin_dr_set_control (unsigned long control)
 431 {
 432   i386_darwin_dr_set (DR_CONTROL, control);
 433 }
 434
 435 static void
 436 i386_darwin_dr_set_addr (int regnum, CORE_ADDR addr)
 437 {
 438   gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR);
 439
 440   i386_darwin_dr_set (DR_FIRSTADDR + regnum, addr);
 441 }
 442
 443 static CORE_ADDR
 444 i386_darwin_dr_get_addr (int regnum)
 445 {
 446   return i386_darwin_dr_get (regnum);
 447 }
 448
 449 static unsigned long
 450 i386_darwin_dr_get_status (void)
 451 {
 452   return i386_darwin_dr_get (DR_STATUS);
 453 }
 454
 455 static unsigned long
 456 i386_darwin_dr_get_control (void)
 457 {
 458   return i386_darwin_dr_get (DR_CONTROL);
 459 }
 460
 461 void
 462 darwin_check_osabi (darwin_inferior *inf, thread_t thread)
 463 {
 464   if (gdbarch_osabi (target_gdbarch ()) == GDB_OSABI_UNKNOWN)
 465     {
 466       /* Attaching to a process.  Let's figure out what kind it is.  */
 467       x86_thread_state_t gp_regs;
 468       struct gdbarch_info info;
 469       unsigned int gp_count = x86_THREAD_STATE_COUNT;
 470       kern_return_t ret;
 471
 472       ret = thread_get_state (thread, x86_THREAD_STATE,
 473                               (thread_state_t) &gp_regs, &gp_count);
 474       if (ret != KERN_SUCCESS)
 475         {
 476           MACH_CHECK_ERROR (ret);
 477           return;
 478         }
 479
 480       gdbarch_info_init (&info);
 481       gdbarch_info_fill (&info);
 482       info.byte_order = gdbarch_byte_order (target_gdbarch ());
 483       info.osabi = GDB_OSABI_DARWIN;
 484       if (gp_regs.tsh.flavor == x86_THREAD_STATE64)
 485         info.bfd_arch_info = bfd_lookup_arch (bfd_arch_i386,
 486                                               bfd_mach_x86_64);
 487       else
 488         info.bfd_arch_info = bfd_lookup_arch (bfd_arch_i386,
 489                                               bfd_mach_i386_i386);
 490       gdbarch_update_p (info);
 491     }
 492 }
 493
 494 #define X86_EFLAGS_T 0x100UL
 495
 496 /* Returning from a signal trampoline is done by calling a
 497    special system call (sigreturn).  This system call
 498    restores the registers that were saved when the signal was
 499    raised, including %eflags/%rflags.  That means that single-stepping
 500    won't work.  Instead, we'll have to modify the signal context
 501    that's about to be restored, and set the trace flag there.  */
 502
 503 static int
 504 i386_darwin_sstep_at_sigreturn (x86_thread_state_t *regs)
 505 {
 506   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 507   static const gdb_byte darwin_syscall[] = { 0xcd, 0x80 }; /* int 0x80 */
 508   gdb_byte buf[sizeof (darwin_syscall)];
 509
 510   /* Check if PC is at a sigreturn system call.  */
 511   if (target_read_memory (regs->uts.ts32.__eip, buf, sizeof (buf)) == 0
 512       && memcmp (buf, darwin_syscall, sizeof (darwin_syscall)) == 0
 513       && regs->uts.ts32.__eax == 0xb8 /* SYS_sigreturn */)
 514     {
 515       ULONGEST uctx_addr;
 516       ULONGEST mctx_addr;
 517       ULONGEST flags_addr;
 518       unsigned int eflags;
 519
 520       uctx_addr = read_memory_unsigned_integer
 521                     (regs->uts.ts32.__esp + 4, 4, byte_order);
 522       mctx_addr = read_memory_unsigned_integer
 523                     (uctx_addr + 28, 4, byte_order);
 524
 525       flags_addr = mctx_addr + 12 + 9 * 4;
 526       read_memory (flags_addr, (gdb_byte *) &eflags, 4);
 527       eflags |= X86_EFLAGS_T;
 528       write_memory (flags_addr, (gdb_byte *) &eflags, 4);
 529
 530       return 1;
 531     }
 532   return 0;
 533 }
 534
 535 #ifdef BFD64
 536 static int
 537 amd64_darwin_sstep_at_sigreturn (x86_thread_state_t *regs)
 538 {
 539   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 540   static const gdb_byte darwin_syscall[] = { 0x0f, 0x05 }; /* syscall */
 541   gdb_byte buf[sizeof (darwin_syscall)];
 542
 543   /* Check if PC is at a sigreturn system call.  */
 544   if (target_read_memory (regs->uts.ts64.__rip, buf, sizeof (buf)) == 0
 545       && memcmp (buf, darwin_syscall, sizeof (darwin_syscall)) == 0
 546       && (regs->uts.ts64.__rax & 0xffffffff) == 0x20000b8 /* SYS_sigreturn */)
 547     {
 548       ULONGEST mctx_addr;
 549       ULONGEST flags_addr;
 550       unsigned int rflags;
 551
 552       mctx_addr = read_memory_unsigned_integer
 553                     (regs->uts.ts64.__rdi + 48, 8, byte_order);
 554       flags_addr = mctx_addr + 16 + 17 * 8;
 555
 556       /* AMD64 is little endian.  */
 557       read_memory (flags_addr, (gdb_byte *) &rflags, 4);
 558       rflags |= X86_EFLAGS_T;
 559       write_memory (flags_addr, (gdb_byte *) &rflags, 4);
 560
 561       return 1;
 562     }
 563   return 0;
 564 }
 565 #endif
 566
 567 void
 568 darwin_set_sstep (thread_t thread, int enable)
 569 {
 570   x86_thread_state_t regs;
 571   unsigned int count = x86_THREAD_STATE_COUNT;
 572   kern_return_t kret;
 573
 574   kret = thread_get_state (thread, x86_THREAD_STATE,
 575                            (thread_state_t) &regs, &count);
 576   if (kret != KERN_SUCCESS)
 577     {
 578       printf_unfiltered (_("darwin_set_sstep: error %x, thread=%x\n"),
 579                          kret, thread);
 580       return;
 581     }
 582
 583   switch (regs.tsh.flavor)
 584     {
 585     case x86_THREAD_STATE32:
 586       {
 587         __uint32_t bit = enable ? X86_EFLAGS_T : 0;
 588
 589         if (enable && i386_darwin_sstep_at_sigreturn (&regs))
 590           return;
 591         if ((regs.uts.ts32.__eflags & X86_EFLAGS_T) == bit)
 592           return;
 593         regs.uts.ts32.__eflags
 594           = (regs.uts.ts32.__eflags & ~X86_EFLAGS_T) | bit;
 595         kret = thread_set_state (thread, x86_THREAD_STATE,
 596                                  (thread_state_t) &regs, count);
 597         MACH_CHECK_ERROR (kret);
 598       }
 599       break;
 600 #ifdef BFD64
 601     case x86_THREAD_STATE64:
 602       {
 603         __uint64_t bit = enable ? X86_EFLAGS_T : 0;
 604
 605         if (enable && amd64_darwin_sstep_at_sigreturn (&regs))
 606           return;
 607         if ((regs.uts.ts64.__rflags & X86_EFLAGS_T) == bit)
 608           return;
 609         regs.uts.ts64.__rflags
 610           = (regs.uts.ts64.__rflags & ~X86_EFLAGS_T) | bit;
 611         kret = thread_set_state (thread, x86_THREAD_STATE,
 612                                  (thread_state_t) &regs, count);
 613         MACH_CHECK_ERROR (kret);
 614       }
 615       break;
 616 #endif
 617     default:
 618       error (_("darwin_set_sstep: unknown flavour: %d"), regs.tsh.flavor);
 619     }
 620 }
 621
 622 void
 623 darwin_complete_target (struct target_ops *target)
 624 {
 625 #ifdef BFD64
 626   amd64_native_gregset64_reg_offset = amd64_darwin_thread_state_reg_offset;
 627   amd64_native_gregset64_num_regs = amd64_darwin_thread_state_num_regs;
 628   amd64_native_gregset32_reg_offset = i386_darwin_thread_state_reg_offset;
 629   amd64_native_gregset32_num_regs = i386_darwin_thread_state_num_regs;
 630 #endif
 631
 632   i386_use_watchpoints (target);
 633
 634   i386_dr_low.set_control = i386_darwin_dr_set_control;
 635   i386_dr_low.set_addr = i386_darwin_dr_set_addr;
 636   i386_dr_low.get_addr = i386_darwin_dr_get_addr;
 637   i386_dr_low.get_status = i386_darwin_dr_get_status;
 638   i386_dr_low.get_control = i386_darwin_dr_get_control;
 639
 640   /* Let's assume that the kernel is 64 bits iff the executable is.  */
 641 #ifdef __x86_64__
 642   i386_set_debug_register_length (8);
 643 #else
 644   i386_set_debug_register_length (4);
 645 #endif
 646
 647   target->to_fetch_registers = i386_darwin_fetch_inferior_registers;
 648   target->to_store_registers = i386_darwin_store_inferior_registers;
 649 }