server/ptrace.c

   1 /*
   2  * Server-side ptrace support
   3  *
   4  * Copyright (C) 1999 Alexandre Julliard
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  19  */
  20
  21 #include "config.h"
  22
  23 #include <assert.h>
  24 #include <errno.h>
  25 #include <stdio.h>
  26 #include <signal.h>
  27 #include <stdarg.h>
  28 #include <sys/types.h>
  29 #ifdef HAVE_SYS_PTRACE_H
  30 # include <sys/ptrace.h>
  31 #endif
  32 #ifdef HAVE_SYS_REG_H
  33 #include <sys/reg.h>
  34 #endif
  35 #ifdef HAVE_SYS_PARAM_H
  36 # include <sys/param.h>
  37 #endif
  38 #ifdef HAVE_SYS_WAIT_H
  39 # include <sys/wait.h>
  40 #endif
  41 #include <unistd.h>
  42
  43 #include "ntstatus.h"
  44 #define WIN32_NO_STATUS
  45 #include "winternl.h"
  46
  47 #include "file.h"
  48 #include "process.h"
  49 #include "thread.h"
  50
  51 #ifndef PTRACE_CONT
  52 #define PTRACE_CONT PT_CONTINUE
  53 #endif
  54 #ifndef PTRACE_SINGLESTEP
  55 #define PTRACE_SINGLESTEP PT_STEP
  56 #endif
  57 #ifndef PTRACE_ATTACH
  58 #define PTRACE_ATTACH PT_ATTACH
  59 #endif
  60 #ifndef PTRACE_DETACH
  61 #define PTRACE_DETACH PT_DETACH
  62 #endif
  63 #ifndef PTRACE_PEEKDATA
  64 #define PTRACE_PEEKDATA PT_READ_D
  65 #endif
  66 #ifndef PTRACE_POKEDATA
  67 #define PTRACE_POKEDATA PT_WRITE_D
  68 #endif
  69 #ifndef PTRACE_PEEKUSER
  70 #define PTRACE_PEEKUSER PT_READ_U
  71 #endif
  72 #ifndef PTRACE_POKEUSER
  73 #define PTRACE_POKEUSER PT_WRITE_U
  74 #endif
  75
  76 #ifdef PT_GETDBREGS
  77 #define PTRACE_GETDBREGS PT_GETDBREGS
  78 #endif
  79 #ifdef PT_SETDBREGS
  80 #define PTRACE_SETDBREGS PT_SETDBREGS
  81 #endif
  82
  83 #ifndef HAVE_SYS_PTRACE_H
  84 #define PT_CONTINUE 0
  85 #define PT_ATTACH   1
  86 #define PT_DETACH   2
  87 #define PT_READ_D   3
  88 #define PT_WRITE_D  4
  89 #define PT_STEP     5
  90 inline static int ptrace(int req, ...) { errno = EPERM; return -1; /*FAIL*/ }
  91 #endif  /* HAVE_SYS_PTRACE_H */
  92
  93 /* handle a status returned by wait4 */
  94 static int handle_child_status( struct thread *thread, int pid, int status, int want_sig )
  95 {
  96     if (WIFSTOPPED(status))
  97     {
  98         int sig = WSTOPSIG(status);
  99         if (debug_level && thread)
 100             fprintf( stderr, "%04x: *signal* signal=%d\n", thread->id, sig );
 101         if (sig != want_sig)
 102         {
 103             /* ignore other signals for now */
 104             ptrace( PTRACE_CONT, pid, (caddr_t)1, sig );
 105         }
 106         return sig;
 107     }
 108     if (thread && (WIFSIGNALED(status) || WIFEXITED(status)))
 109     {
 110         thread->unix_pid = -1;
 111         thread->unix_tid = -1;
 112         if (debug_level)
 113         {
 114             if (WIFSIGNALED(status))
 115                 fprintf( stderr, "%04x: *exited* signal=%d\n",
 116                          thread->id, WTERMSIG(status) );
 117             else
 118                 fprintf( stderr, "%04x: *exited* status=%d\n",
 119                          thread->id, WEXITSTATUS(status) );
 120         }
 121     }
 122     return 0;
 123 }
 124
 125 /* wait4 wrapper to handle missing __WALL flag in older kernels */
 126 static inline pid_t wait4_wrapper( pid_t pid, int *status, int options, struct rusage *usage )
 127 {
 128 #ifdef __WALL
 129     static int wall_flag = __WALL;
 130
 131     for (;;)
 132     {
 133         pid_t ret = wait4( pid, status, options | wall_flag, usage );
 134         if (ret != -1 || !wall_flag || errno != EINVAL) return ret;
 135         wall_flag = 0;
 136     }
 137 #else
 138     return wait4( pid, status, options, usage );
 139 #endif
 140 }
 141
 142 /* handle a SIGCHLD signal */
 143 void sigchld_callback(void)
 144 {
 145     int pid, status;
 146
 147     for (;;)
 148     {
 149         if (!(pid = wait4_wrapper( -1, &status, WUNTRACED | WNOHANG, NULL ))) break;
 150         if (pid != -1) handle_child_status( get_thread_from_pid(pid), pid, status, -1 );
 151         else break;
 152     }
 153 }
 154
 155 /* return the Unix pid to use in ptrace calls for a given thread */
 156 static int get_ptrace_pid( struct thread *thread )
 157 {
 158     if (thread->unix_tid != -1) return thread->unix_tid;
 159     return thread->unix_pid;
 160 }
 161
 162 /* wait for a ptraced child to get a certain signal */
 163 static int wait4_thread( struct thread *thread, int signal )
 164 {
 165     int res, status;
 166
 167     start_watchdog();
 168     for (;;)
 169     {
 170         if ((res = wait4_wrapper( get_ptrace_pid(thread), &status, WUNTRACED, NULL )) == -1)
 171         {
 172             if (errno == EINTR)
 173             {
 174                 if (!watchdog_triggered()) continue;
 175                 if (debug_level) fprintf( stderr, "%04x: *watchdog* wait4 aborted\n", thread->id );
 176             }
 177             else if (errno == ECHILD)  /* must have died */
 178             {
 179                 thread->unix_pid = -1;
 180                 thread->unix_tid = -1;
 181             }
 182             else perror( "wait4" );
 183             stop_watchdog();
 184             return 0;
 185         }
 186         res = handle_child_status( thread, res, status, signal );
 187         if (!res || res == signal) break;
 188     }
 189     stop_watchdog();
 190     return (thread->unix_pid != -1);
 191 }
 192
 193 /* send a signal to a specific thread */
 194 static inline int tkill( int tgid, int pid, int sig )
 195 {
 196     int ret = -ENOSYS;
 197
 198 #ifdef __linux__
 199 # ifdef __i386__
 200     __asm__( "pushl %%ebx\n\t"
 201              "movl %2,%%ebx\n\t"
 202              "int $0x80\n\t"
 203              "popl %%ebx\n\t"
 204              : "=a" (ret)
 205              : "0" (270) /*SYS_tgkill*/, "r" (tgid), "c" (pid), "d" (sig) );
 206     if (ret == -ENOSYS)
 207         __asm__( "pushl %%ebx\n\t"
 208                  "movl %2,%%ebx\n\t"
 209                  "int $0x80\n\t"
 210                  "popl %%ebx\n\t"
 211                  : "=a" (ret)
 212                  : "0" (238) /*SYS_tkill*/, "r" (pid), "c" (sig) );
 213 # elif defined(__x86_64__)
 214     __asm__( "syscall" : "=a" (ret)
 215              : "0" (200) /*SYS_tkill*/, "D" (pid), "S" (sig) );
 216 # endif
 217 #endif  /* __linux__ */
 218
 219     if (ret >= 0) return ret;
 220     errno = -ret;
 221     return -1;
 222 }
 223
 224 /* send a Unix signal to a specific thread */
 225 int send_thread_signal( struct thread *thread, int sig )
 226 {
 227     int ret = -1;
 228
 229     if (thread->unix_pid != -1)
 230     {
 231         if (thread->unix_tid != -1)
 232         {
 233             ret = tkill( thread->unix_pid, thread->unix_tid, sig );
 234             if (ret == -1 && errno == ENOSYS) ret = kill( thread->unix_pid, sig );
 235         }
 236         else ret = kill( thread->unix_pid, sig );
 237
 238         if (ret == -1 && errno == ESRCH) /* thread got killed */
 239         {
 240             thread->unix_pid = -1;
 241             thread->unix_tid = -1;
 242         }
 243     }
 244     return (ret != -1);
 245 }
 246
 247 /* resume a thread after we have used ptrace on it */
 248 static void resume_after_ptrace( struct thread *thread )
 249 {
 250     if (thread->unix_pid == -1) return;
 251     if (ptrace( PTRACE_DETACH, get_ptrace_pid(thread), (caddr_t)1, 0 ) == -1)
 252     {
 253         if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1;  /* thread got killed */
 254     }
 255 }
 256
 257 /* suspend a thread to allow using ptrace on it */
 258 /* you must do a resume_after_ptrace when finished with the thread */
 259 static int suspend_for_ptrace( struct thread *thread )
 260 {
 261     /* can't stop a thread while initialisation is in progress */
 262     if (thread->unix_pid == -1 || !is_process_init_done(thread->process)) goto error;
 263
 264     /* this may fail if the client is already being debugged */
 265     if (ptrace( PTRACE_ATTACH, get_ptrace_pid(thread), 0, 0 ) == -1)
 266     {
 267         if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1;  /* thread got killed */
 268         goto error;
 269     }
 270     if (wait4_thread( thread, SIGSTOP )) return 1;
 271     resume_after_ptrace( thread );
 272  error:
 273     set_error( STATUS_ACCESS_DENIED );
 274     return 0;
 275 }
 276
 277 /* read an int from a thread address space */
 278 static int read_thread_int( struct thread *thread, const int *addr, int *data )
 279 {
 280     errno = 0;
 281     *data = ptrace( PTRACE_PEEKDATA, get_ptrace_pid(thread), (caddr_t)addr, 0 );
 282     if ( *data == -1 && errno)
 283     {
 284         file_set_error();
 285         return -1;
 286     }
 287     return 0;
 288 }
 289
 290 /* write an int to a thread address space */
 291 static int write_thread_int( struct thread *thread, int *addr, int data, unsigned int mask )
 292 {
 293     int res;
 294     if (mask != ~0)
 295     {
 296         if (read_thread_int( thread, addr, &res ) == -1) return -1;
 297         data = (data & mask) | (res & ~mask);
 298     }
 299     if ((res = ptrace( PTRACE_POKEDATA, get_ptrace_pid(thread), (caddr_t)addr, data )) == -1)
 300         file_set_error();
 301     return res;
 302 }
 303
 304 /* read data from a process memory space */
 305 int read_process_memory( struct process *process, const void *ptr, size_t size, char *dest )
 306 {
 307     struct thread *thread = get_process_first_thread( process );
 308     unsigned int first_offset, last_offset, len;
 309     int data, *addr;
 310
 311     if (!thread)  /* process is dead */
 312     {
 313         set_error( STATUS_ACCESS_DENIED );
 314         return 0;
 315     }
 316
 317     first_offset = (unsigned long)ptr % sizeof(int);
 318     last_offset = (size + first_offset) % sizeof(int);
 319     if (!last_offset) last_offset = sizeof(int);
 320
 321     addr = (int *)((char *)ptr - first_offset);
 322     len = (size + first_offset + sizeof(int) - 1) / sizeof(int);
 323
 324     if (suspend_for_ptrace( thread ))
 325     {
 326         if (len > 1)
 327         {
 328             if (read_thread_int( thread, addr++, &data ) == -1) goto done;
 329             memcpy( dest, (char *)&data + first_offset, sizeof(int) - first_offset );
 330             dest += sizeof(int) - first_offset;
 331             first_offset = 0;
 332             len--;
 333         }
 334
 335         while (len > 1)
 336         {
 337             if (read_thread_int( thread, addr++, &data ) == -1) goto done;
 338             memcpy( dest, &data, sizeof(int) );
 339             dest += sizeof(int);
 340             len--;
 341         }
 342
 343         if (read_thread_int( thread, addr++, &data ) == -1) goto done;
 344         memcpy( dest, (char *)&data + first_offset, last_offset - first_offset );
 345         len--;
 346
 347     done:
 348         resume_after_ptrace( thread );
 349     }
 350     return !len;
 351 }
 352
 353 /* make sure we can write to the whole address range */
 354 /* len is the total size (in ints) */
 355 static int check_process_write_access( struct thread *thread, int *addr, size_t len )
 356 {
 357     int page = get_page_size() / sizeof(int);
 358
 359     for (;;)
 360     {
 361         if (write_thread_int( thread, addr, 0, 0 ) == -1) return 0;
 362         if (len <= page) break;
 363         addr += page;
 364         len -= page;
 365     }
 366     return (write_thread_int( thread, addr + len - 1, 0, 0 ) != -1);
 367 }
 368
 369 /* write data to a process memory space */
 370 int write_process_memory( struct process *process, void *ptr, size_t size, const char *src )
 371 {
 372     struct thread *thread = get_process_first_thread( process );
 373     int ret = 0, data = 0;
 374     size_t len;
 375     int *addr;
 376     unsigned int first_mask, first_offset, last_mask, last_offset;
 377
 378     if (!thread)  /* process is dead */
 379     {
 380         set_error( STATUS_ACCESS_DENIED );
 381         return 0;
 382     }
 383
 384     /* compute the mask for the first int */
 385     first_mask = ~0;
 386     first_offset = (unsigned long)ptr % sizeof(int);
 387     memset( &first_mask, 0, first_offset );
 388
 389     /* compute the mask for the last int */
 390     last_offset = (size + first_offset) % sizeof(int);
 391     if (!last_offset) last_offset = sizeof(int);
 392     last_mask = 0;
 393     memset( &last_mask, 0xff, last_offset );
 394
 395     addr = (int *)((char *)ptr - first_offset);
 396     len = (size + first_offset + sizeof(int) - 1) / sizeof(int);
 397
 398     if (suspend_for_ptrace( thread ))
 399     {
 400         if (!check_process_write_access( thread, addr, len ))
 401         {
 402             set_error( STATUS_ACCESS_DENIED );
 403             goto done;
 404         }
 405         /* first word is special */
 406         if (len > 1)
 407         {
 408             memcpy( (char *)&data + first_offset, src, sizeof(int) - first_offset );
 409             src += sizeof(int) - first_offset;
 410             if (write_thread_int( thread, addr++, data, first_mask ) == -1) goto done;
 411             first_offset = 0;
 412             len--;
 413         }
 414         else last_mask &= first_mask;
 415
 416         while (len > 1)
 417         {
 418             memcpy( &data, src, sizeof(int) );
 419             src += sizeof(int);
 420             if (write_thread_int( thread, addr++, data, ~0 ) == -1) goto done;
 421             len--;
 422         }
 423
 424         /* last word is special too */
 425         memcpy( (char *)&data + first_offset, src, last_offset - first_offset );
 426         if (write_thread_int( thread, addr, data, last_mask ) == -1) goto done;
 427         ret = 1;
 428
 429     done:
 430         resume_after_ptrace( thread );
 431     }
 432     return ret;
 433 }
 434
 435 /* retrieve an LDT selector entry */
 436 void get_selector_entry( struct thread *thread, int entry, unsigned int *base,
 437                          unsigned int *limit, unsigned char *flags )
 438 {
 439     if (!thread->process->ldt_copy)
 440     {
 441         set_error( STATUS_ACCESS_DENIED );
 442         return;
 443     }
 444     if (entry >= 8192)
 445     {
 446         set_error( STATUS_INVALID_PARAMETER );  /* FIXME */
 447         return;
 448     }
 449     if (suspend_for_ptrace( thread ))
 450     {
 451         unsigned char flags_buf[4];
 452         int *addr = (int *)thread->process->ldt_copy + entry;
 453         if (read_thread_int( thread, addr, (int *)base ) == -1) goto done;
 454         if (read_thread_int( thread, addr + 8192, (int *)limit ) == -1) goto done;
 455         addr = (int *)thread->process->ldt_copy + 2*8192 + (entry >> 2);
 456         if (read_thread_int( thread, addr, (int *)flags_buf ) == -1) goto done;
 457         *flags = flags_buf[entry & 3];
 458     done:
 459         resume_after_ptrace( thread );
 460     }
 461 }
 462
 463
 464 #if defined(linux) && (defined(__i386__) || defined(__x86_64__))
 465
 466 #ifdef HAVE_SYS_USER_H
 467 # include <sys/user.h>
 468 #endif
 469
 470 /* debug register offset in struct user */
 471 #define DR_OFFSET(dr) ((int)((((struct user *)0)->u_debugreg) + (dr)))
 472
 473 /* retrieve a debug register */
 474 static inline int get_debug_reg( int pid, int num, DWORD *data )
 475 {
 476     int res;
 477     errno = 0;
 478     res = ptrace( PTRACE_PEEKUSER, pid, DR_OFFSET(num), 0 );
 479     if ((res == -1) && errno)
 480     {
 481         file_set_error();
 482         return -1;
 483     }
 484     *data = res;
 485     return 0;
 486 }
 487
 488 /* retrieve the thread x86 registers */
 489 void get_thread_context( struct thread *thread, CONTEXT *context, unsigned int flags )
 490 {
 491     int pid = get_ptrace_pid(thread);
 492
 493     /* all other regs are handled on the client side */
 494     assert( (flags | CONTEXT_i386) == CONTEXT_DEBUG_REGISTERS );
 495
 496     if (!suspend_for_ptrace( thread )) return;
 497
 498     if (get_debug_reg( pid, 0, &context->Dr0 ) == -1) goto error;
 499     if (get_debug_reg( pid, 1, &context->Dr1 ) == -1) goto error;
 500     if (get_debug_reg( pid, 2, &context->Dr2 ) == -1) goto error;
 501     if (get_debug_reg( pid, 3, &context->Dr3 ) == -1) goto error;
 502     if (get_debug_reg( pid, 6, &context->Dr6 ) == -1) goto error;
 503     if (get_debug_reg( pid, 7, &context->Dr7 ) == -1) goto error;
 504     context->ContextFlags |= CONTEXT_DEBUG_REGISTERS;
 505     resume_after_ptrace( thread );
 506     return;
 507  error:
 508     file_set_error();
 509     resume_after_ptrace( thread );
 510 }
 511
 512 /* set the thread x86 registers */
 513 void set_thread_context( struct thread *thread, const CONTEXT *context, unsigned int flags )
 514 {
 515     int pid = get_ptrace_pid( thread );
 516
 517     /* all other regs are handled on the client side */
 518     assert( (flags | CONTEXT_i386) == CONTEXT_DEBUG_REGISTERS );
 519
 520     if (!suspend_for_ptrace( thread )) return;
 521
 522     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(0), context->Dr0 ) == -1) goto error;
 523     if (thread->context) thread->context->Dr0 = context->Dr0;
 524     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(1), context->Dr1 ) == -1) goto error;
 525     if (thread->context) thread->context->Dr1 = context->Dr1;
 526     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(2), context->Dr2 ) == -1) goto error;
 527     if (thread->context) thread->context->Dr2 = context->Dr2;
 528     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(3), context->Dr3 ) == -1) goto error;
 529     if (thread->context) thread->context->Dr3 = context->Dr3;
 530     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(6), context->Dr6 ) == -1) goto error;
 531     if (thread->context) thread->context->Dr6 = context->Dr6;
 532     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->Dr7 ) == -1) goto error;
 533     if (thread->context) thread->context->Dr7 = context->Dr7;
 534     resume_after_ptrace( thread );
 535     return;
 536  error:
 537     file_set_error();
 538     resume_after_ptrace( thread );
 539 }
 540
 541 #elif defined(__i386__) && defined(PTRACE_GETDBREGS) && defined(PTRACE_SETDBREGS) && \
 542     (defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__OpenBSD__) || defined(__NetBSD__))
 543
 544 #include <machine/reg.h>
 545
 546 /* retrieve the thread x86 registers */
 547 void get_thread_context( struct thread *thread, CONTEXT *context, unsigned int flags )
 548 {
 549     int pid = get_ptrace_pid(thread);
 550     struct dbreg dbregs;
 551
 552     /* all other regs are handled on the client side */
 553     assert( (flags | CONTEXT_i386) == CONTEXT_DEBUG_REGISTERS );
 554
 555     if (!suspend_for_ptrace( thread )) return;
 556
 557     if (ptrace( PTRACE_GETDBREGS, pid, (caddr_t) &dbregs, 0 ) == -1) file_set_error();
 558     else
 559     {
 560 #ifdef DBREG_DRX
 561         /* needed for FreeBSD, the structure fields have changed under 5.x */
 562         context->Dr0 = DBREG_DRX((&dbregs), 0);
 563         context->Dr1 = DBREG_DRX((&dbregs), 1);
 564         context->Dr2 = DBREG_DRX((&dbregs), 2);
 565         context->Dr3 = DBREG_DRX((&dbregs), 3);
 566         context->Dr6 = DBREG_DRX((&dbregs), 6);
 567         context->Dr7 = DBREG_DRX((&dbregs), 7);
 568 #else
 569         context->Dr0 = dbregs.dr0;
 570         context->Dr1 = dbregs.dr1;
 571         context->Dr2 = dbregs.dr2;
 572         context->Dr3 = dbregs.dr3;
 573         context->Dr6 = dbregs.dr6;
 574         context->Dr7 = dbregs.dr7;
 575 #endif
 576         context->ContextFlags |= CONTEXT_DEBUG_REGISTERS;
 577     }
 578     resume_after_ptrace( thread );
 579 }
 580
 581 /* set the thread x86 registers */
 582 void set_thread_context( struct thread *thread, const CONTEXT *context, unsigned int flags )
 583 {
 584     int pid = get_ptrace_pid(thread);
 585     struct dbreg dbregs;
 586
 587     /* all other regs are handled on the client side */
 588     assert( (flags | CONTEXT_i386) == CONTEXT_DEBUG_REGISTERS );
 589
 590     if (!suspend_for_ptrace( thread )) return;
 591
 592 #ifdef DBREG_DRX
 593     /* needed for FreeBSD, the structure fields have changed under 5.x */
 594     DBREG_DRX((&dbregs), 0) = context->Dr0;
 595     DBREG_DRX((&dbregs), 1) = context->Dr1;
 596     DBREG_DRX((&dbregs), 2) = context->Dr2;
 597     DBREG_DRX((&dbregs), 3) = context->Dr3;
 598     DBREG_DRX((&dbregs), 4) = 0;
 599     DBREG_DRX((&dbregs), 5) = 0;
 600     DBREG_DRX((&dbregs), 6) = context->Dr6;
 601     DBREG_DRX((&dbregs), 7) = context->Dr7;
 602 #else
 603     dbregs.dr0 = context->Dr0;
 604     dbregs.dr1 = context->Dr1;
 605     dbregs.dr2 = context->Dr2;
 606     dbregs.dr3 = context->Dr3;
 607     dbregs.dr4 = 0;
 608     dbregs.dr5 = 0;
 609     dbregs.dr6 = context->Dr6;
 610     dbregs.dr7 = context->Dr7;
 611 #endif
 612     if (ptrace( PTRACE_SETDBREGS, pid, (caddr_t) &dbregs, 0 ) == -1) file_set_error();
 613     else if (thread->context)  /* update the cached values */
 614     {
 615         thread->context->Dr0 = context->Dr0;
 616         thread->context->Dr1 = context->Dr1;
 617         thread->context->Dr2 = context->Dr2;
 618         thread->context->Dr3 = context->Dr3;
 619         thread->context->Dr6 = context->Dr6;
 620         thread->context->Dr7 = context->Dr7;
 621     }
 622     resume_after_ptrace( thread );
 623 }
 624
 625 #else  /* linux || __FreeBSD__ */
 626
 627 /* retrieve the thread x86 registers */
 628 void get_thread_context( struct thread *thread, CONTEXT *context, unsigned int flags )
 629 {
 630 }
 631
 632 /* set the thread x86 debug registers */
 633 void set_thread_context( struct thread *thread, const CONTEXT *context, unsigned int flags )
 634 {
 635 }
 636
 637 #endif  /* linux || __FreeBSD__ */