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_PARAM_H
  33 # include <sys/param.h>
  34 #endif
  35 #ifdef HAVE_SYS_WAIT_H
  36 # include <sys/wait.h>
  37 #endif
  38 #include <unistd.h>
  39
  40 #include "ntstatus.h"
  41 #define WIN32_NO_STATUS
  42 #include "winternl.h"
  43
  44 #include "file.h"
  45 #include "process.h"
  46 #include "thread.h"
  47
  48 #ifdef USE_PTRACE
  49
  50 #ifndef PTRACE_CONT
  51 #define PTRACE_CONT PT_CONTINUE
  52 #endif
  53 #ifndef PTRACE_SINGLESTEP
  54 #define PTRACE_SINGLESTEP PT_STEP
  55 #endif
  56 #ifndef PTRACE_ATTACH
  57 #define PTRACE_ATTACH PT_ATTACH
  58 #endif
  59 #ifndef PTRACE_DETACH
  60 #define PTRACE_DETACH PT_DETACH
  61 #endif
  62 #ifndef PTRACE_PEEKDATA
  63 #define PTRACE_PEEKDATA PT_READ_D
  64 #endif
  65 #ifndef PTRACE_POKEDATA
  66 #define PTRACE_POKEDATA PT_WRITE_D
  67 #endif
  68 #ifndef PTRACE_PEEKUSER
  69 #define PTRACE_PEEKUSER PT_READ_U
  70 #endif
  71 #ifndef PTRACE_POKEUSER
  72 #define PTRACE_POKEUSER PT_WRITE_U
  73 #endif
  74
  75 #ifdef PT_GETDBREGS
  76 #define PTRACE_GETDBREGS PT_GETDBREGS
  77 #endif
  78 #ifdef PT_SETDBREGS
  79 #define PTRACE_SETDBREGS PT_SETDBREGS
  80 #endif
  81
  82 #ifndef HAVE_SYS_PTRACE_H
  83 #define PT_CONTINUE 0
  84 #define PT_ATTACH   1
  85 #define PT_DETACH   2
  86 #define PT_READ_D   3
  87 #define PT_WRITE_D  4
  88 #define PT_STEP     5
  89 static inline int ptrace(int req, ...) { errno = EPERM; return -1; /*FAIL*/ }
  90 #endif  /* HAVE_SYS_PTRACE_H */
  91
  92 /* handle a status returned by wait4 */
  93 static int handle_child_status( struct thread *thread, int pid, int status, int want_sig )
  94 {
  95     if (WIFSTOPPED(status))
  96     {
  97         int sig = WSTOPSIG(status);
  98         if (debug_level && thread)
  99             fprintf( stderr, "%04x: *signal* signal=%d\n", thread->id, sig );
 100         if (sig != want_sig)
 101         {
 102             /* ignore other signals for now */
 103             ptrace( PTRACE_CONT, pid, (caddr_t)1, sig );
 104         }
 105         return sig;
 106     }
 107     if (thread && (WIFSIGNALED(status) || WIFEXITED(status)))
 108     {
 109         thread->unix_pid = -1;
 110         thread->unix_tid = -1;
 111         if (debug_level)
 112         {
 113             if (WIFSIGNALED(status))
 114                 fprintf( stderr, "%04x: *exited* signal=%d\n",
 115                          thread->id, WTERMSIG(status) );
 116             else
 117                 fprintf( stderr, "%04x: *exited* status=%d\n",
 118                          thread->id, WEXITSTATUS(status) );
 119         }
 120     }
 121     return 0;
 122 }
 123
 124 /* wait4 wrapper to handle missing __WALL flag in older kernels */
 125 static inline pid_t wait4_wrapper( pid_t pid, int *status, int options, struct rusage *usage )
 126 {
 127 #ifdef __WALL
 128     static int wall_flag = __WALL;
 129
 130     for (;;)
 131     {
 132         pid_t ret = wait4( pid, status, options | wall_flag, usage );
 133         if (ret != -1 || !wall_flag || errno != EINVAL) return ret;
 134         wall_flag = 0;
 135     }
 136 #else
 137     return wait4( pid, status, options, usage );
 138 #endif
 139 }
 140
 141 /* handle a SIGCHLD signal */
 142 void sigchld_callback(void)
 143 {
 144     int pid, status;
 145
 146     for (;;)
 147     {
 148         if (!(pid = wait4_wrapper( -1, &status, WUNTRACED | WNOHANG, NULL ))) break;
 149         if (pid != -1)
 150         {
 151             struct thread *thread = get_thread_from_tid( pid );
 152             if (!thread) thread = get_thread_from_pid( pid );
 153             handle_child_status( thread, pid, status, -1 );
 154         }
 155         else break;
 156     }
 157 }
 158
 159 /* return the Unix pid to use in ptrace calls for a given process */
 160 static int get_ptrace_pid( struct thread *thread )
 161 {
 162 #ifdef linux  /* linux always uses thread id */
 163     if (thread->unix_tid != -1) return thread->unix_tid;
 164 #endif
 165     return thread->unix_pid;
 166 }
 167
 168 /* return the Unix tid to use in ptrace calls for a given thread */
 169 static int get_ptrace_tid( struct thread *thread )
 170 {
 171     if (thread->unix_tid != -1) return thread->unix_tid;
 172     return thread->unix_pid;
 173 }
 174
 175 /* wait for a ptraced child to get a certain signal */
 176 static int wait4_thread( struct thread *thread, int signal )
 177 {
 178     int res, status;
 179
 180     start_watchdog();
 181     for (;;)
 182     {
 183         if ((res = wait4_wrapper( get_ptrace_pid(thread), &status, WUNTRACED, NULL )) == -1)
 184         {
 185             if (errno == EINTR)
 186             {
 187                 if (!watchdog_triggered()) continue;
 188                 if (debug_level) fprintf( stderr, "%04x: *watchdog* wait4 aborted\n", thread->id );
 189             }
 190             else if (errno == ECHILD)  /* must have died */
 191             {
 192                 thread->unix_pid = -1;
 193                 thread->unix_tid = -1;
 194             }
 195             else perror( "wait4" );
 196             stop_watchdog();
 197             return 0;
 198         }
 199         res = handle_child_status( thread, res, status, signal );
 200         if (!res || res == signal) break;
 201     }
 202     stop_watchdog();
 203     return (thread->unix_pid != -1);
 204 }
 205
 206 /* send a signal to a specific thread */
 207 static inline int tkill( int tgid, int pid, int sig )
 208 {
 209     int ret = -ENOSYS;
 210
 211 #ifdef __linux__
 212 # ifdef __i386__
 213     __asm__( "pushl %%ebx\n\t"
 214              "movl %2,%%ebx\n\t"
 215              "int $0x80\n\t"
 216              "popl %%ebx\n\t"
 217              : "=a" (ret)
 218              : "0" (270) /*SYS_tgkill*/, "r" (tgid), "c" (pid), "d" (sig) );
 219     if (ret == -ENOSYS)
 220         __asm__( "pushl %%ebx\n\t"
 221                  "movl %2,%%ebx\n\t"
 222                  "int $0x80\n\t"
 223                  "popl %%ebx\n\t"
 224                  : "=a" (ret)
 225                  : "0" (238) /*SYS_tkill*/, "r" (pid), "c" (sig) );
 226 # elif defined(__x86_64__)
 227     __asm__( "syscall" : "=a" (ret)
 228              : "0" (200) /*SYS_tkill*/, "D" (pid), "S" (sig) );
 229 # endif
 230 #endif  /* __linux__ */
 231
 232     if (ret >= 0) return ret;
 233     errno = -ret;
 234     return -1;
 235 }
 236
 237 /* initialize the process tracing mechanism */
 238 void init_tracing_mechanism(void)
 239 {
 240     /* no initialization needed for ptrace */
 241 }
 242
 243 /* initialize the per-process tracing mechanism */
 244 void init_process_tracing( struct process *process )
 245 {
 246     /* ptrace setup is done on-demand */
 247 }
 248
 249 /* terminate the per-process tracing mechanism */
 250 void finish_process_tracing( struct process *process )
 251 {
 252 }
 253
 254 /* send a Unix signal to a specific thread */
 255 int send_thread_signal( struct thread *thread, int sig )
 256 {
 257     int ret = -1;
 258
 259     if (thread->unix_pid != -1)
 260     {
 261         if (thread->unix_tid != -1)
 262         {
 263             ret = tkill( thread->unix_pid, thread->unix_tid, sig );
 264             if (ret == -1 && errno == ENOSYS) ret = kill( thread->unix_pid, sig );
 265         }
 266         else ret = kill( thread->unix_pid, sig );
 267
 268         if (ret == -1 && errno == ESRCH) /* thread got killed */
 269         {
 270             thread->unix_pid = -1;
 271             thread->unix_tid = -1;
 272         }
 273     }
 274     if (debug_level && ret != -1)
 275         fprintf( stderr, "%04x: *sent signal* signal=%d\n", thread->id, sig );
 276     return (ret != -1);
 277 }
 278
 279 /* resume a thread after we have used ptrace on it */
 280 static void resume_after_ptrace( struct thread *thread )
 281 {
 282     if (thread->unix_pid == -1) return;
 283     if (ptrace( PTRACE_DETACH, get_ptrace_pid(thread), (caddr_t)1, 0 ) == -1)
 284     {
 285         if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1;  /* thread got killed */
 286     }
 287 }
 288
 289 /* suspend a thread to allow using ptrace on it */
 290 /* you must do a resume_after_ptrace when finished with the thread */
 291 static int suspend_for_ptrace( struct thread *thread )
 292 {
 293     /* can't stop a thread while initialisation is in progress */
 294     if (thread->unix_pid == -1 || !is_process_init_done(thread->process)) goto error;
 295
 296     /* this may fail if the client is already being debugged */
 297     if (ptrace( PTRACE_ATTACH, get_ptrace_pid(thread), 0, 0 ) == -1)
 298     {
 299         if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1;  /* thread got killed */
 300         goto error;
 301     }
 302     if (wait4_thread( thread, SIGSTOP )) return 1;
 303     resume_after_ptrace( thread );
 304  error:
 305     set_error( STATUS_ACCESS_DENIED );
 306     return 0;
 307 }
 308
 309 /* read an int from a thread address space */
 310 static int read_thread_int( struct thread *thread, int *addr, int *data )
 311 {
 312     errno = 0;
 313     *data = ptrace( PTRACE_PEEKDATA, get_ptrace_pid(thread), (caddr_t)addr, 0 );
 314     if ( *data == -1 && errno)
 315     {
 316         file_set_error();
 317         return -1;
 318     }
 319     return 0;
 320 }
 321
 322 /* write an int to a thread address space */
 323 static int write_thread_int( struct thread *thread, int *addr, int data, unsigned int mask )
 324 {
 325     int res;
 326     if (mask != ~0u)
 327     {
 328         if (read_thread_int( thread, addr, &res ) == -1) return -1;
 329         data = (data & mask) | (res & ~mask);
 330     }
 331     if ((res = ptrace( PTRACE_POKEDATA, get_ptrace_pid(thread), (caddr_t)addr, data )) == -1)
 332         file_set_error();
 333     return res;
 334 }
 335
 336 /* return a thread of the process suitable for ptracing */
 337 static struct thread *get_ptrace_thread( struct process *process )
 338 {
 339     struct thread *thread;
 340
 341     LIST_FOR_EACH_ENTRY( thread, &process->thread_list, struct thread, proc_entry )
 342     {
 343         if (thread->unix_pid != -1) return thread;
 344     }
 345     set_error( STATUS_ACCESS_DENIED );  /* process is dead */
 346     return NULL;
 347 }
 348
 349 /* read data from a process memory space */
 350 int read_process_memory( struct process *process, const void *ptr, data_size_t size, char *dest )
 351 {
 352     struct thread *thread = get_ptrace_thread( process );
 353     unsigned int first_offset, last_offset, len;
 354     int data, *addr;
 355
 356     if (!thread) return 0;
 357
 358     first_offset = (unsigned long)ptr % sizeof(int);
 359     last_offset = (size + first_offset) % sizeof(int);
 360     if (!last_offset) last_offset = sizeof(int);
 361
 362     addr = (int *)((char *)ptr - first_offset);
 363     len = (size + first_offset + sizeof(int) - 1) / sizeof(int);
 364
 365     if (suspend_for_ptrace( thread ))
 366     {
 367         if (len > 1)
 368         {
 369             if (read_thread_int( thread, addr++, &data ) == -1) goto done;
 370             memcpy( dest, (char *)&data + first_offset, sizeof(int) - first_offset );
 371             dest += sizeof(int) - first_offset;
 372             first_offset = 0;
 373             len--;
 374         }
 375
 376         while (len > 1)
 377         {
 378             if (read_thread_int( thread, addr++, &data ) == -1) goto done;
 379             memcpy( dest, &data, sizeof(int) );
 380             dest += sizeof(int);
 381             len--;
 382         }
 383
 384         if (read_thread_int( thread, addr++, &data ) == -1) goto done;
 385         memcpy( dest, (char *)&data + first_offset, last_offset - first_offset );
 386         len--;
 387
 388     done:
 389         resume_after_ptrace( thread );
 390     }
 391     return !len;
 392 }
 393
 394 /* make sure we can write to the whole address range */
 395 /* len is the total size (in ints) */
 396 static int check_process_write_access( struct thread *thread, int *addr, data_size_t len )
 397 {
 398     int page = get_page_size() / sizeof(int);
 399
 400     for (;;)
 401     {
 402         if (write_thread_int( thread, addr, 0, 0 ) == -1) return 0;
 403         if (len <= page) break;
 404         addr += page;
 405         len -= page;
 406     }
 407     return (write_thread_int( thread, addr + len - 1, 0, 0 ) != -1);
 408 }
 409
 410 /* write data to a process memory space */
 411 int write_process_memory( struct process *process, void *ptr, data_size_t size, const char *src )
 412 {
 413     struct thread *thread = get_ptrace_thread( process );
 414     int ret = 0, data = 0;
 415     data_size_t len;
 416     int *addr;
 417     unsigned int first_mask, first_offset, last_mask, last_offset;
 418
 419     if (!thread) return 0;
 420
 421     /* compute the mask for the first int */
 422     first_mask = ~0;
 423     first_offset = (unsigned long)ptr % sizeof(int);
 424     memset( &first_mask, 0, first_offset );
 425
 426     /* compute the mask for the last int */
 427     last_offset = (size + first_offset) % sizeof(int);
 428     if (!last_offset) last_offset = sizeof(int);
 429     last_mask = 0;
 430     memset( &last_mask, 0xff, last_offset );
 431
 432     addr = (int *)((char *)ptr - first_offset);
 433     len = (size + first_offset + sizeof(int) - 1) / sizeof(int);
 434
 435     if (suspend_for_ptrace( thread ))
 436     {
 437         if (!check_process_write_access( thread, addr, len ))
 438         {
 439             set_error( STATUS_ACCESS_DENIED );
 440             goto done;
 441         }
 442         /* first word is special */
 443         if (len > 1)
 444         {
 445             memcpy( (char *)&data + first_offset, src, sizeof(int) - first_offset );
 446             src += sizeof(int) - first_offset;
 447             if (write_thread_int( thread, addr++, data, first_mask ) == -1) goto done;
 448             first_offset = 0;
 449             len--;
 450         }
 451         else last_mask &= first_mask;
 452
 453         while (len > 1)
 454         {
 455             memcpy( &data, src, sizeof(int) );
 456             src += sizeof(int);
 457             if (write_thread_int( thread, addr++, data, ~0 ) == -1) goto done;
 458             len--;
 459         }
 460
 461         /* last word is special too */
 462         memcpy( (char *)&data + first_offset, src, last_offset - first_offset );
 463         if (write_thread_int( thread, addr, data, last_mask ) == -1) goto done;
 464         ret = 1;
 465
 466     done:
 467         resume_after_ptrace( thread );
 468     }
 469     return ret;
 470 }
 471
 472 /* retrieve an LDT selector entry */
 473 void get_selector_entry( struct thread *thread, int entry, unsigned int *base,
 474                          unsigned int *limit, unsigned char *flags )
 475 {
 476     if (!thread->process->ldt_copy)
 477     {
 478         set_error( STATUS_ACCESS_DENIED );
 479         return;
 480     }
 481     if (entry >= 8192)
 482     {
 483         set_error( STATUS_ACCESS_VIOLATION );
 484         return;
 485     }
 486     if (suspend_for_ptrace( thread ))
 487     {
 488         unsigned char flags_buf[4];
 489         int *addr = (int *)thread->process->ldt_copy + entry;
 490         if (read_thread_int( thread, addr, (int *)base ) == -1) goto done;
 491         if (read_thread_int( thread, addr + 8192, (int *)limit ) == -1) goto done;
 492         addr = (int *)thread->process->ldt_copy + 2*8192 + (entry >> 2);
 493         if (read_thread_int( thread, addr, (int *)flags_buf ) == -1) goto done;
 494         *flags = flags_buf[entry & 3];
 495     done:
 496         resume_after_ptrace( thread );
 497     }
 498 }
 499
 500
 501 #if defined(linux) && (defined(__i386__) || defined(__x86_64__))
 502
 503 #ifdef HAVE_SYS_USER_H
 504 # include <sys/user.h>
 505 #endif
 506
 507 /* debug register offset in struct user */
 508 #define DR_OFFSET(dr) ((((struct user *)0)->u_debugreg) + (dr))
 509
 510 /* retrieve the thread x86 registers */
 511 void get_thread_context( struct thread *thread, CONTEXT *context, unsigned int flags )
 512 {
 513     int i, pid = get_ptrace_tid(thread);
 514     long data[8];
 515
 516     /* all other regs are handled on the client side */
 517     assert( (flags | CONTEXT_i386) == CONTEXT_DEBUG_REGISTERS );
 518
 519     if (!suspend_for_ptrace( thread )) return;
 520
 521     for (i = 0; i < 8; i++)
 522     {
 523         if (i == 4 || i == 5) continue;
 524         errno = 0;
 525         data[i] = ptrace( PTRACE_PEEKUSER, pid, DR_OFFSET(i), 0 );
 526         if ((data[i] == -1) && errno)
 527         {
 528             file_set_error();
 529             goto done;
 530         }
 531     }
 532     context->Dr0 = data[0];
 533     context->Dr1 = data[1];
 534     context->Dr2 = data[2];
 535     context->Dr3 = data[3];
 536     context->Dr6 = data[6];
 537     context->Dr7 = data[7];
 538     context->ContextFlags |= CONTEXT_DEBUG_REGISTERS;
 539 done:
 540     resume_after_ptrace( thread );
 541 }
 542
 543 /* set the thread x86 registers */
 544 void set_thread_context( struct thread *thread, const CONTEXT *context, unsigned int flags )
 545 {
 546     int pid = get_ptrace_tid( thread );
 547
 548     /* all other regs are handled on the client side */
 549     assert( (flags | CONTEXT_i386) == CONTEXT_DEBUG_REGISTERS );
 550
 551     if (!suspend_for_ptrace( thread )) return;
 552
 553     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(0), context->Dr0 ) == -1) goto error;
 554     if (thread->context) thread->context->Dr0 = context->Dr0;
 555     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(1), context->Dr1 ) == -1) goto error;
 556     if (thread->context) thread->context->Dr1 = context->Dr1;
 557     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(2), context->Dr2 ) == -1) goto error;
 558     if (thread->context) thread->context->Dr2 = context->Dr2;
 559     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(3), context->Dr3 ) == -1) goto error;
 560     if (thread->context) thread->context->Dr3 = context->Dr3;
 561     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(6), context->Dr6 ) == -1) goto error;
 562     if (thread->context) thread->context->Dr6 = context->Dr6;
 563     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->Dr7 ) == -1) goto error;
 564     if (thread->context) thread->context->Dr7 = context->Dr7;
 565     resume_after_ptrace( thread );
 566     return;
 567  error:
 568     file_set_error();
 569     resume_after_ptrace( thread );
 570 }
 571
 572 #elif defined(__i386__) && defined(PTRACE_GETDBREGS) && defined(PTRACE_SETDBREGS) && \
 573     (defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__OpenBSD__) || defined(__NetBSD__))
 574
 575 #include <machine/reg.h>
 576
 577 /* retrieve the thread x86 registers */
 578 void get_thread_context( struct thread *thread, CONTEXT *context, unsigned int flags )
 579 {
 580     int pid = get_ptrace_tid(thread);
 581     struct dbreg dbregs;
 582
 583     /* all other regs are handled on the client side */
 584     assert( (flags | CONTEXT_i386) == CONTEXT_DEBUG_REGISTERS );
 585
 586     if (!suspend_for_ptrace( thread )) return;
 587
 588     if (ptrace( PTRACE_GETDBREGS, pid, (caddr_t) &dbregs, 0 ) == -1) file_set_error();
 589     else
 590     {
 591 #ifdef DBREG_DRX
 592         /* needed for FreeBSD, the structure fields have changed under 5.x */
 593         context->Dr0 = DBREG_DRX((&dbregs), 0);
 594         context->Dr1 = DBREG_DRX((&dbregs), 1);
 595         context->Dr2 = DBREG_DRX((&dbregs), 2);
 596         context->Dr3 = DBREG_DRX((&dbregs), 3);
 597         context->Dr6 = DBREG_DRX((&dbregs), 6);
 598         context->Dr7 = DBREG_DRX((&dbregs), 7);
 599 #else
 600         context->Dr0 = dbregs.dr0;
 601         context->Dr1 = dbregs.dr1;
 602         context->Dr2 = dbregs.dr2;
 603         context->Dr3 = dbregs.dr3;
 604         context->Dr6 = dbregs.dr6;
 605         context->Dr7 = dbregs.dr7;
 606 #endif
 607         context->ContextFlags |= CONTEXT_DEBUG_REGISTERS;
 608     }
 609     resume_after_ptrace( thread );
 610 }
 611
 612 /* set the thread x86 registers */
 613 void set_thread_context( struct thread *thread, const CONTEXT *context, unsigned int flags )
 614 {
 615     int pid = get_ptrace_tid(thread);
 616     struct dbreg dbregs;
 617
 618     /* all other regs are handled on the client side */
 619     assert( (flags | CONTEXT_i386) == CONTEXT_DEBUG_REGISTERS );
 620
 621     if (!suspend_for_ptrace( thread )) return;
 622
 623 #ifdef DBREG_DRX
 624     /* needed for FreeBSD, the structure fields have changed under 5.x */
 625     DBREG_DRX((&dbregs), 0) = context->Dr0;
 626     DBREG_DRX((&dbregs), 1) = context->Dr1;
 627     DBREG_DRX((&dbregs), 2) = context->Dr2;
 628     DBREG_DRX((&dbregs), 3) = context->Dr3;
 629     DBREG_DRX((&dbregs), 4) = 0;
 630     DBREG_DRX((&dbregs), 5) = 0;
 631     DBREG_DRX((&dbregs), 6) = context->Dr6;
 632     DBREG_DRX((&dbregs), 7) = context->Dr7;
 633 #else
 634     dbregs.dr0 = context->Dr0;
 635     dbregs.dr1 = context->Dr1;
 636     dbregs.dr2 = context->Dr2;
 637     dbregs.dr3 = context->Dr3;
 638     dbregs.dr4 = 0;
 639     dbregs.dr5 = 0;
 640     dbregs.dr6 = context->Dr6;
 641     dbregs.dr7 = context->Dr7;
 642 #endif
 643     if (ptrace( PTRACE_SETDBREGS, pid, (caddr_t) &dbregs, 0 ) == -1) file_set_error();
 644     else if (thread->context)  /* update the cached values */
 645     {
 646         thread->context->Dr0 = context->Dr0;
 647         thread->context->Dr1 = context->Dr1;
 648         thread->context->Dr2 = context->Dr2;
 649         thread->context->Dr3 = context->Dr3;
 650         thread->context->Dr6 = context->Dr6;
 651         thread->context->Dr7 = context->Dr7;
 652     }
 653     resume_after_ptrace( thread );
 654 }
 655
 656 #else  /* linux || __FreeBSD__ */
 657
 658 /* retrieve the thread x86 registers */
 659 void get_thread_context( struct thread *thread, CONTEXT *context, unsigned int flags )
 660 {
 661 }
 662
 663 /* set the thread x86 debug registers */
 664 void set_thread_context( struct thread *thread, const CONTEXT *context, unsigned int flags )
 665 {
 666 }
 667
 668 #endif  /* linux || __FreeBSD__ */
 669
 670 #endif  /* USE_PTRACE */