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 #include "wine/port.h"
  23
  24 #include <assert.h>
  25 #include <errno.h>
  26 #include <fcntl.h>
  27 #include <stdio.h>
  28 #include <signal.h>
  29 #include <stdarg.h>
  30 #include <sys/types.h>
  31 #ifdef HAVE_SYS_PTRACE_H
  32 # include <sys/ptrace.h>
  33 #endif
  34 #ifdef HAVE_SYS_PARAM_H
  35 # include <sys/param.h>
  36 #endif
  37 #ifdef HAVE_SYS_WAIT_H
  38 # include <sys/wait.h>
  39 #endif
  40 #ifdef HAVE_SYS_SYSCALL_H
  41 # include <sys/syscall.h>
  42 #endif
  43 #ifdef HAVE_SYS_UCONTEXT_H
  44 # include <sys/ucontext.h>
  45 #endif
  46 #ifdef HAVE_SYS_THR_H
  47 # include <sys/thr.h>
  48 #endif
  49 #include <unistd.h>
  50
  51 #include "ntstatus.h"
  52 #define WIN32_NO_STATUS
  53 #include "winternl.h"
  54
  55 #include "file.h"
  56 #include "process.h"
  57 #include "thread.h"
  58
  59 #ifdef USE_PTRACE
  60
  61 #ifndef PTRACE_CONT
  62 #define PTRACE_CONT PT_CONTINUE
  63 #endif
  64 #ifndef PTRACE_SINGLESTEP
  65 #define PTRACE_SINGLESTEP PT_STEP
  66 #endif
  67 #ifndef PTRACE_ATTACH
  68 #define PTRACE_ATTACH PT_ATTACH
  69 #endif
  70 #ifndef PTRACE_DETACH
  71 #define PTRACE_DETACH PT_DETACH
  72 #endif
  73 #ifndef PTRACE_PEEKDATA
  74 #define PTRACE_PEEKDATA PT_READ_D
  75 #endif
  76 #ifndef PTRACE_POKEDATA
  77 #define PTRACE_POKEDATA PT_WRITE_D
  78 #endif
  79 #ifndef PTRACE_PEEKUSER
  80 #define PTRACE_PEEKUSER PT_READ_U
  81 #endif
  82 #ifndef PTRACE_POKEUSER
  83 #define PTRACE_POKEUSER PT_WRITE_U
  84 #endif
  85
  86 #ifdef PT_GETDBREGS
  87 #define PTRACE_GETDBREGS PT_GETDBREGS
  88 #endif
  89 #ifdef PT_SETDBREGS
  90 #define PTRACE_SETDBREGS PT_SETDBREGS
  91 #endif
  92
  93 #ifndef HAVE_SYS_PTRACE_H
  94 #define PT_CONTINUE 0
  95 #define PT_ATTACH   1
  96 #define PT_DETACH   2
  97 #define PT_READ_D   3
  98 #define PT_WRITE_D  4
  99 #define PT_STEP     5
 100 static inline int ptrace(int req, ...) { errno = EPERM; return -1; /*FAIL*/ }
 101 #endif  /* HAVE_SYS_PTRACE_H */
 102
 103 #ifndef __WALL
 104 #define __WALL 0
 105 #endif
 106
 107 /* handle a status returned by waitpid */
 108 static int handle_child_status( struct thread *thread, int pid, int status, int want_sig )
 109 {
 110     if (WIFSTOPPED(status))
 111     {
 112         int sig = WSTOPSIG(status);
 113         if (debug_level && thread)
 114             fprintf( stderr, "%04x: *signal* signal=%d\n", thread->id, sig );
 115         if (sig != want_sig)
 116         {
 117             /* ignore other signals for now */
 118             ptrace( PTRACE_CONT, pid, (caddr_t)1, sig );
 119         }
 120         return sig;
 121     }
 122     if (thread && (WIFSIGNALED(status) || WIFEXITED(status)))
 123     {
 124         thread->unix_pid = -1;
 125         thread->unix_tid = -1;
 126         if (debug_level)
 127         {
 128             if (WIFSIGNALED(status))
 129                 fprintf( stderr, "%04x: *exited* signal=%d\n",
 130                          thread->id, WTERMSIG(status) );
 131             else
 132                 fprintf( stderr, "%04x: *exited* status=%d\n",
 133                          thread->id, WEXITSTATUS(status) );
 134         }
 135     }
 136     return 0;
 137 }
 138
 139 /* handle a SIGCHLD signal */
 140 void sigchld_callback(void)
 141 {
 142     int pid, status;
 143
 144     for (;;)
 145     {
 146         if (!(pid = waitpid( -1, &status, WUNTRACED | WNOHANG | __WALL ))) break;
 147         if (pid != -1)
 148         {
 149             struct thread *thread = get_thread_from_tid( pid );
 150             if (!thread) thread = get_thread_from_pid( pid );
 151             handle_child_status( thread, pid, status, -1 );
 152         }
 153         else break;
 154     }
 155 }
 156
 157 /* return the Unix pid to use in ptrace calls for a given process */
 158 static int get_ptrace_pid( struct thread *thread )
 159 {
 160 #ifdef linux  /* linux always uses thread id */
 161     if (thread->unix_tid != -1) return thread->unix_tid;
 162 #endif
 163     return thread->unix_pid;
 164 }
 165
 166 /* return the Unix tid to use in ptrace calls for a given thread */
 167 static int get_ptrace_tid( struct thread *thread )
 168 {
 169     if (thread->unix_tid != -1) return thread->unix_tid;
 170     return thread->unix_pid;
 171 }
 172
 173 /* wait for a ptraced child to get a certain signal */
 174 static int waitpid_thread( struct thread *thread, int signal )
 175 {
 176     int res, status;
 177
 178     start_watchdog();
 179     for (;;)
 180     {
 181         if ((res = waitpid( get_ptrace_pid(thread), &status, WUNTRACED | __WALL )) == -1)
 182         {
 183             if (errno == EINTR)
 184             {
 185                 if (!watchdog_triggered()) continue;
 186                 if (debug_level) fprintf( stderr, "%04x: *watchdog* waitpid aborted\n", thread->id );
 187             }
 188             else if (errno == ECHILD)  /* must have died */
 189             {
 190                 thread->unix_pid = -1;
 191                 thread->unix_tid = -1;
 192             }
 193             else perror( "waitpid" );
 194             stop_watchdog();
 195             return 0;
 196         }
 197         res = handle_child_status( thread, res, status, signal );
 198         if (!res || res == signal) break;
 199     }
 200     stop_watchdog();
 201     return (thread->unix_pid != -1);
 202 }
 203
 204 /* send a signal to a specific thread */
 205 static inline int tkill( int tgid, int pid, int sig )
 206 {
 207 #ifdef __linux__
 208     int ret = syscall( __NR_tgkill, tgid, pid, sig );
 209     if (ret < 0 && errno == ENOSYS) ret = syscall( __NR_tkill, pid, sig );
 210     return ret;
 211 #elif (defined(__FreeBSD__) || defined (__FreeBSD_kernel__)) && defined(HAVE_THR_KILL2)
 212     return thr_kill2( tgid, pid, sig );
 213 #else
 214     errno = ENOSYS;
 215     return -1;
 216 #endif
 217 }
 218
 219 /* initialize the process tracing mechanism */
 220 void init_tracing_mechanism(void)
 221 {
 222     /* no initialization needed for ptrace */
 223 }
 224
 225 /* initialize the per-process tracing mechanism */
 226 void init_process_tracing( struct process *process )
 227 {
 228     /* ptrace setup is done on-demand */
 229 }
 230
 231 /* terminate the per-process tracing mechanism */
 232 void finish_process_tracing( struct process *process )
 233 {
 234 }
 235
 236 /* send a Unix signal to a specific thread */
 237 int send_thread_signal( struct thread *thread, int sig )
 238 {
 239     int ret = -1;
 240
 241     if (thread->unix_pid != -1)
 242     {
 243         if (thread->unix_tid != -1)
 244         {
 245             ret = tkill( thread->unix_pid, thread->unix_tid, sig );
 246             if (ret == -1 && errno == ENOSYS) ret = kill( thread->unix_pid, sig );
 247         }
 248         else ret = kill( thread->unix_pid, sig );
 249
 250         if (ret == -1 && errno == ESRCH) /* thread got killed */
 251         {
 252             thread->unix_pid = -1;
 253             thread->unix_tid = -1;
 254         }
 255     }
 256     if (debug_level && ret != -1)
 257         fprintf( stderr, "%04x: *sent signal* signal=%d\n", thread->id, sig );
 258     return (ret != -1);
 259 }
 260
 261 /* resume a thread after we have used ptrace on it */
 262 static void resume_after_ptrace( struct thread *thread )
 263 {
 264     if (thread->unix_pid == -1) return;
 265     if (ptrace( PTRACE_DETACH, get_ptrace_pid(thread), (caddr_t)1, 0 ) == -1)
 266     {
 267         if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1;  /* thread got killed */
 268     }
 269 }
 270
 271 /* suspend a thread to allow using ptrace on it */
 272 /* you must do a resume_after_ptrace when finished with the thread */
 273 static int suspend_for_ptrace( struct thread *thread )
 274 {
 275     /* can't stop a thread while initialisation is in progress */
 276     if (thread->unix_pid == -1 || !is_process_init_done(thread->process)) goto error;
 277
 278     /* this may fail if the client is already being debugged */
 279     if (ptrace( PTRACE_ATTACH, get_ptrace_pid(thread), 0, 0 ) == -1)
 280     {
 281         if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1;  /* thread got killed */
 282         goto error;
 283     }
 284     if (waitpid_thread( thread, SIGSTOP )) return 1;
 285     resume_after_ptrace( thread );
 286  error:
 287     set_error( STATUS_ACCESS_DENIED );
 288     return 0;
 289 }
 290
 291 /* read a long from a thread address space */
 292 static int read_thread_long( struct thread *thread, void *addr, unsigned long *data )
 293 {
 294     errno = 0;
 295     *data = ptrace( PTRACE_PEEKDATA, get_ptrace_pid(thread), (caddr_t)addr, 0 );
 296     if ( *data == -1 && errno)
 297     {
 298         file_set_error();
 299         return -1;
 300     }
 301     return 0;
 302 }
 303
 304 static int read_thread_int( struct thread *thread, void *addr, unsigned int *data )
 305 {
 306     unsigned long long_data;
 307     int ret;
 308
 309     ret = read_thread_long( thread, addr, &long_data );
 310     *data = long_data;
 311     return ret;
 312 }
 313
 314 /* write a long to a thread address space */
 315 static long write_thread_long( struct thread *thread, void *addr, unsigned long data, unsigned long mask )
 316 {
 317     unsigned long old_data;
 318     int res;
 319
 320     if (mask != ~0ul)
 321     {
 322         if (read_thread_long( thread, addr, &old_data ) == -1) return -1;
 323         data = (data & mask) | (old_data & ~mask);
 324     }
 325     if ((res = ptrace( PTRACE_POKEDATA, get_ptrace_pid(thread), (caddr_t)addr, data )) == -1)
 326         file_set_error();
 327     return res;
 328 }
 329
 330 /* return a thread of the process suitable for ptracing */
 331 static struct thread *get_ptrace_thread( struct process *process )
 332 {
 333     struct thread *thread;
 334
 335     LIST_FOR_EACH_ENTRY( thread, &process->thread_list, struct thread, proc_entry )
 336     {
 337         if (thread->unix_pid != -1) return thread;
 338     }
 339     set_error( STATUS_PROCESS_IS_TERMINATING );  /* process is dead */
 340     return NULL;
 341 }
 342
 343 /* read data from a process memory space */
 344 int read_process_memory( struct process *process, client_ptr_t ptr, data_size_t size, char *dest )
 345 {
 346     struct thread *thread = get_ptrace_thread( process );
 347     unsigned int first_offset, last_offset, len;
 348     unsigned long data, *addr;
 349
 350     if (!thread) return 0;
 351
 352     if ((unsigned long)ptr != ptr)
 353     {
 354         set_error( STATUS_ACCESS_DENIED );
 355         return 0;
 356     }
 357
 358     first_offset = ptr % sizeof(long);
 359     last_offset = (size + first_offset) % sizeof(long);
 360     if (!last_offset) last_offset = sizeof(long);
 361
 362     addr = (unsigned long *)(unsigned long)(ptr - first_offset);
 363     len = (size + first_offset + sizeof(long) - 1) / sizeof(long);
 364
 365     if (suspend_for_ptrace( thread ))
 366     {
 367         if (len > 3)  /* /proc/pid/mem should be faster for large sizes */
 368         {
 369             char procmem[24];
 370             int fd;
 371
 372             sprintf( procmem, "/proc/%u/mem", process->unix_pid );
 373             if ((fd = open( procmem, O_RDONLY )) != -1)
 374             {
 375                 ssize_t ret = pread( fd, dest, size, ptr );
 376                 close( fd );
 377                 if (ret == size)
 378                 {
 379                     len = 0;
 380                     goto done;
 381                 }
 382             }
 383         }
 384
 385         if (len > 1)
 386         {
 387             if (read_thread_long( thread, addr++, &data ) == -1) goto done;
 388             memcpy( dest, (char *)&data + first_offset, sizeof(long) - first_offset );
 389             dest += sizeof(long) - first_offset;
 390             first_offset = 0;
 391             len--;
 392         }
 393
 394         while (len > 1)
 395         {
 396             if (read_thread_long( thread, addr++, &data ) == -1) goto done;
 397             memcpy( dest, &data, sizeof(long) );
 398             dest += sizeof(long);
 399             len--;
 400         }
 401
 402         if (read_thread_long( thread, addr++, &data ) == -1) goto done;
 403         memcpy( dest, (char *)&data + first_offset, last_offset - first_offset );
 404         len--;
 405
 406     done:
 407         resume_after_ptrace( thread );
 408     }
 409     return !len;
 410 }
 411
 412 /* make sure we can write to the whole address range */
 413 /* len is the total size (in ints) */
 414 static int check_process_write_access( struct thread *thread, long *addr, data_size_t len )
 415 {
 416     int page = get_page_size() / sizeof(int);
 417
 418     for (;;)
 419     {
 420         if (write_thread_long( thread, addr, 0, 0 ) == -1) return 0;
 421         if (len <= page) break;
 422         addr += page;
 423         len -= page;
 424     }
 425     return (write_thread_long( thread, addr + len - 1, 0, 0 ) != -1);
 426 }
 427
 428 /* write data to a process memory space */
 429 int write_process_memory( struct process *process, client_ptr_t ptr, data_size_t size, const char *src )
 430 {
 431     struct thread *thread = get_ptrace_thread( process );
 432     int ret = 0;
 433     long data = 0;
 434     data_size_t len;
 435     long *addr;
 436     unsigned long first_mask, first_offset, last_mask, last_offset;
 437
 438     if (!thread) return 0;
 439
 440     if ((unsigned long)ptr != ptr)
 441     {
 442         set_error( STATUS_ACCESS_DENIED );
 443         return 0;
 444     }
 445
 446     /* compute the mask for the first long */
 447     first_mask = ~0;
 448     first_offset = ptr % sizeof(long);
 449     memset( &first_mask, 0, first_offset );
 450
 451     /* compute the mask for the last long */
 452     last_offset = (size + first_offset) % sizeof(long);
 453     if (!last_offset) last_offset = sizeof(long);
 454     last_mask = 0;
 455     memset( &last_mask, 0xff, last_offset );
 456
 457     addr = (long *)(unsigned long)(ptr - first_offset);
 458     len = (size + first_offset + sizeof(long) - 1) / sizeof(long);
 459
 460     if (suspend_for_ptrace( thread ))
 461     {
 462         if (!check_process_write_access( thread, addr, len ))
 463         {
 464             set_error( STATUS_ACCESS_DENIED );
 465             goto done;
 466         }
 467
 468         if (len > 3)
 469         {
 470             char procmem[24];
 471             int fd;
 472
 473             sprintf( procmem, "/proc/%u/mem", process->unix_pid );
 474             if ((fd = open( procmem, O_WRONLY )) != -1)
 475             {
 476                 ssize_t r = pwrite( fd, src, size, ptr );
 477                 close( fd );
 478                 if (r == size)
 479                 {
 480                     ret = 1;
 481                     goto done;
 482                 }
 483             }
 484         }
 485
 486         /* first word is special */
 487         if (len > 1)
 488         {
 489             memcpy( (char *)&data + first_offset, src, sizeof(long) - first_offset );
 490             src += sizeof(long) - first_offset;
 491             if (write_thread_long( thread, addr++, data, first_mask ) == -1) goto done;
 492             first_offset = 0;
 493             len--;
 494         }
 495         else last_mask &= first_mask;
 496
 497         while (len > 1)
 498         {
 499             memcpy( &data, src, sizeof(long) );
 500             src += sizeof(long);
 501             if (write_thread_long( thread, addr++, data, ~0ul ) == -1) goto done;
 502             len--;
 503         }
 504
 505         /* last word is special too */
 506         memcpy( (char *)&data + first_offset, src, last_offset - first_offset );
 507         if (write_thread_long( thread, addr, data, last_mask ) == -1) goto done;
 508         ret = 1;
 509
 510     done:
 511         resume_after_ptrace( thread );
 512     }
 513     return ret;
 514 }
 515
 516 /* retrieve an LDT selector entry */
 517 void get_selector_entry( struct thread *thread, int entry, unsigned int *base,
 518                          unsigned int *limit, unsigned char *flags )
 519 {
 520     if (!thread->process->ldt_copy)
 521     {
 522         set_error( STATUS_ACCESS_DENIED );
 523         return;
 524     }
 525     if (entry >= 8192)
 526     {
 527         set_error( STATUS_ACCESS_VIOLATION );
 528         return;
 529     }
 530     if (suspend_for_ptrace( thread ))
 531     {
 532         unsigned int flags_buf;
 533         unsigned long addr = (unsigned long)thread->process->ldt_copy + (entry * 4);
 534
 535         if (read_thread_int( thread, (void *)addr, base ) == -1) goto done;
 536         if (read_thread_int( thread, (void *)(addr + (8192 * 4)), limit ) == -1) goto done;
 537         addr = (unsigned long)thread->process->ldt_copy + (2 * 8192 * 4) + (entry & ~3);
 538         if (read_thread_int( thread, (void *)addr, &flags_buf ) == -1) goto done;
 539         *flags = flags_buf >> (entry & 3) * 8;
 540     done:
 541         resume_after_ptrace( thread );
 542     }
 543 }
 544
 545
 546 #if defined(linux) && (defined(HAVE_SYS_USER_H) || defined(HAVE_ASM_USER_H)) \
 547     && (defined(__i386__) || defined(__x86_64__))
 548
 549 #ifdef HAVE_SYS_USER_H
 550 #include <sys/user.h>
 551 #elif defined(HAVE_ASM_USER_H)
 552 #include <asm/user.h>
 553 #endif
 554
 555 /* debug register offset in struct user */
 556 #define DR_OFFSET(dr) ((((struct user *)0)->u_debugreg) + (dr))
 557
 558 /* initialize registers in new thread if necessary */
 559 void init_thread_context( struct thread *thread )
 560 {
 561     /* Linux doesn't clear all registers, but hopefully enough to avoid spurious breakpoints */
 562     thread->system_regs = 0;
 563 }
 564
 565 /* retrieve the thread x86 registers */
 566 void get_thread_context( struct thread *thread, context_t *context, unsigned int flags )
 567 {
 568     int i, pid = get_ptrace_tid(thread);
 569     long data[8];
 570
 571     /* all other regs are handled on the client side */
 572     assert( flags == SERVER_CTX_DEBUG_REGISTERS );
 573
 574     if (!suspend_for_ptrace( thread )) return;
 575
 576     if (!(thread->system_regs & SERVER_CTX_DEBUG_REGISTERS))
 577     {
 578         /* caller has initialized everything to 0 already, just return */
 579         context->flags |= SERVER_CTX_DEBUG_REGISTERS;
 580         goto done;
 581     }
 582
 583     for (i = 0; i < 8; i++)
 584     {
 585         if (i == 4 || i == 5) continue;
 586         errno = 0;
 587         data[i] = ptrace( PTRACE_PEEKUSER, pid, DR_OFFSET(i), 0 );
 588         if ((data[i] == -1) && errno)
 589         {
 590             file_set_error();
 591             goto done;
 592         }
 593     }
 594     switch (context->cpu)
 595     {
 596     case CPU_x86:
 597         context->debug.i386_regs.dr0 = data[0];
 598         context->debug.i386_regs.dr1 = data[1];
 599         context->debug.i386_regs.dr2 = data[2];
 600         context->debug.i386_regs.dr3 = data[3];
 601         context->debug.i386_regs.dr6 = data[6];
 602         context->debug.i386_regs.dr7 = data[7];
 603         break;
 604     case CPU_x86_64:
 605         context->debug.x86_64_regs.dr0 = data[0];
 606         context->debug.x86_64_regs.dr1 = data[1];
 607         context->debug.x86_64_regs.dr2 = data[2];
 608         context->debug.x86_64_regs.dr3 = data[3];
 609         context->debug.x86_64_regs.dr6 = data[6];
 610         context->debug.x86_64_regs.dr7 = data[7];
 611         break;
 612     default:
 613         set_error( STATUS_INVALID_PARAMETER );
 614         goto done;
 615     }
 616     context->flags |= SERVER_CTX_DEBUG_REGISTERS;
 617 done:
 618     resume_after_ptrace( thread );
 619 }
 620
 621 /* set the thread x86 registers */
 622 void set_thread_context( struct thread *thread, const context_t *context, unsigned int flags )
 623 {
 624     int pid = get_ptrace_tid( thread );
 625
 626     /* all other regs are handled on the client side */
 627     assert( flags == SERVER_CTX_DEBUG_REGISTERS );
 628
 629     if (!suspend_for_ptrace( thread )) return;
 630
 631     /* force all breakpoint lengths to 1, workaround for kernel bug 200965 */
 632     ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), 0x11110055 );
 633
 634     switch (context->cpu)
 635     {
 636     case CPU_x86:
 637         /* Linux 2.6.33+ does DR0-DR3 alignment validation, so it has to know LEN bits first */
 638         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->debug.i386_regs.dr7 & 0xffff0000 ) == -1) goto error;
 639         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(0), context->debug.i386_regs.dr0 ) == -1) goto error;
 640         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(1), context->debug.i386_regs.dr1 ) == -1) goto error;
 641         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(2), context->debug.i386_regs.dr2 ) == -1) goto error;
 642         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(3), context->debug.i386_regs.dr3 ) == -1) goto error;
 643         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(6), context->debug.i386_regs.dr6 ) == -1) goto error;
 644         /* Linux 2.6.33+ needs enable bits set briefly to update value returned by PEEKUSER later */
 645         ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->debug.i386_regs.dr7 | 0x55 );
 646         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->debug.i386_regs.dr7 ) == -1) goto error;
 647         thread->system_regs |= SERVER_CTX_DEBUG_REGISTERS;
 648         break;
 649     case CPU_x86_64:
 650         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->debug.x86_64_regs.dr7 & 0xffff0000 ) == -1) goto error;
 651         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(0), context->debug.x86_64_regs.dr0 ) == -1) goto error;
 652         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(1), context->debug.x86_64_regs.dr1 ) == -1) goto error;
 653         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(2), context->debug.x86_64_regs.dr2 ) == -1) goto error;
 654         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(3), context->debug.x86_64_regs.dr3 ) == -1) goto error;
 655         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(6), context->debug.x86_64_regs.dr6 ) == -1) goto error;
 656         ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->debug.x86_64_regs.dr7 | 0x55 );
 657         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->debug.x86_64_regs.dr7 ) == -1) goto error;
 658         thread->system_regs |= SERVER_CTX_DEBUG_REGISTERS;
 659         break;
 660     default:
 661         set_error( STATUS_INVALID_PARAMETER );
 662     }
 663     resume_after_ptrace( thread );
 664     return;
 665  error:
 666     file_set_error();
 667     resume_after_ptrace( thread );
 668 }
 669
 670 #elif defined(__i386__) && defined(PTRACE_GETDBREGS) && defined(PTRACE_SETDBREGS) && \
 671     (defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__OpenBSD__) || defined(__NetBSD__) || defined(__DragonFly__))
 672
 673 #include <machine/reg.h>
 674
 675 /* initialize registers in new thread if necessary */
 676 void init_thread_context( struct thread *thread )
 677 {
 678     if (!(thread->system_regs & SERVER_CTX_DEBUG_REGISTERS)) return;
 679
 680     /* FreeBSD doesn't clear the debug registers in new threads */
 681     if (suspend_for_ptrace( thread ))
 682     {
 683         struct dbreg dbregs;
 684
 685         memset( &dbregs, 0, sizeof(dbregs) );
 686         ptrace( PTRACE_SETDBREGS, get_ptrace_tid( thread ), (caddr_t)&dbregs, 0 );
 687         resume_after_ptrace( thread );
 688     }
 689     thread->system_regs = 0;
 690 }
 691
 692 /* retrieve the thread x86 registers */
 693 void get_thread_context( struct thread *thread, context_t *context, unsigned int flags )
 694 {
 695     int pid = get_ptrace_tid(thread);
 696     struct dbreg dbregs;
 697
 698     /* all other regs are handled on the client side */
 699     assert( flags == SERVER_CTX_DEBUG_REGISTERS );
 700
 701     if (!suspend_for_ptrace( thread )) return;
 702
 703     if (ptrace( PTRACE_GETDBREGS, pid, (caddr_t) &dbregs, 0 ) == -1) file_set_error();
 704     else
 705     {
 706 #ifdef DBREG_DRX
 707         /* needed for FreeBSD, the structure fields have changed under 5.x */
 708         context->debug.i386_regs.dr0 = DBREG_DRX((&dbregs), 0);
 709         context->debug.i386_regs.dr1 = DBREG_DRX((&dbregs), 1);
 710         context->debug.i386_regs.dr2 = DBREG_DRX((&dbregs), 2);
 711         context->debug.i386_regs.dr3 = DBREG_DRX((&dbregs), 3);
 712         context->debug.i386_regs.dr6 = DBREG_DRX((&dbregs), 6);
 713         context->debug.i386_regs.dr7 = DBREG_DRX((&dbregs), 7);
 714 #elif defined(__NetBSD__)
 715         context->debug.i386_regs.dr0 = dbregs.dr[0];
 716         context->debug.i386_regs.dr1 = dbregs.dr[1];
 717         context->debug.i386_regs.dr2 = dbregs.dr[2];
 718         context->debug.i386_regs.dr3 = dbregs.dr[3];
 719         context->debug.i386_regs.dr6 = dbregs.dr[6];
 720         context->debug.i386_regs.dr7 = dbregs.dr[7];
 721 #else
 722         context->debug.i386_regs.dr0 = dbregs.dr0;
 723         context->debug.i386_regs.dr1 = dbregs.dr1;
 724         context->debug.i386_regs.dr2 = dbregs.dr2;
 725         context->debug.i386_regs.dr3 = dbregs.dr3;
 726         context->debug.i386_regs.dr6 = dbregs.dr6;
 727         context->debug.i386_regs.dr7 = dbregs.dr7;
 728 #endif
 729         context->flags |= SERVER_CTX_DEBUG_REGISTERS;
 730     }
 731     resume_after_ptrace( thread );
 732 }
 733
 734 /* set the thread x86 registers */
 735 void set_thread_context( struct thread *thread, const context_t *context, unsigned int flags )
 736 {
 737     int pid = get_ptrace_tid(thread);
 738     struct dbreg dbregs;
 739
 740     /* all other regs are handled on the client side */
 741     assert( flags == SERVER_CTX_DEBUG_REGISTERS );
 742
 743     if (!suspend_for_ptrace( thread )) return;
 744
 745 #ifdef DBREG_DRX
 746     /* needed for FreeBSD, the structure fields have changed under 5.x */
 747     DBREG_DRX((&dbregs), 0) = context->debug.i386_regs.dr0;
 748     DBREG_DRX((&dbregs), 1) = context->debug.i386_regs.dr1;
 749     DBREG_DRX((&dbregs), 2) = context->debug.i386_regs.dr2;
 750     DBREG_DRX((&dbregs), 3) = context->debug.i386_regs.dr3;
 751     DBREG_DRX((&dbregs), 4) = 0;
 752     DBREG_DRX((&dbregs), 5) = 0;
 753     DBREG_DRX((&dbregs), 6) = context->debug.i386_regs.dr6;
 754     DBREG_DRX((&dbregs), 7) = context->debug.i386_regs.dr7;
 755 #elif defined(__NetBSD__)
 756     dbregs.dr[0] = context->debug.i386_regs.dr0;
 757     dbregs.dr[1] = context->debug.i386_regs.dr1;
 758     dbregs.dr[2] = context->debug.i386_regs.dr2;
 759     dbregs.dr[3] = context->debug.i386_regs.dr3;
 760     dbregs.dr[4] = 0;
 761     dbregs.dr[5] = 0;
 762     dbregs.dr[6] = context->debug.i386_regs.dr6;
 763     dbregs.dr[7] = context->debug.i386_regs.dr7;
 764 #else
 765     dbregs.dr0 = context->debug.i386_regs.dr0;
 766     dbregs.dr1 = context->debug.i386_regs.dr1;
 767     dbregs.dr2 = context->debug.i386_regs.dr2;
 768     dbregs.dr3 = context->debug.i386_regs.dr3;
 769     dbregs.dr4 = 0;
 770     dbregs.dr5 = 0;
 771     dbregs.dr6 = context->debug.i386_regs.dr6;
 772     dbregs.dr7 = context->debug.i386_regs.dr7;
 773 #endif
 774     if (ptrace( PTRACE_SETDBREGS, pid, (caddr_t)&dbregs, 0 ) != -1)
 775     {
 776         thread->system_regs |= SERVER_CTX_DEBUG_REGISTERS;
 777     }
 778     else file_set_error();
 779
 780     resume_after_ptrace( thread );
 781 }
 782
 783 #else  /* linux || __FreeBSD__ */
 784
 785 /* initialize registers in new thread if necessary */
 786 void init_thread_context( struct thread *thread )
 787 {
 788 }
 789
 790 /* retrieve the thread x86 registers */
 791 void get_thread_context( struct thread *thread, context_t *context, unsigned int flags )
 792 {
 793 }
 794
 795 /* set the thread x86 debug registers */
 796 void set_thread_context( struct thread *thread, const context_t *context, unsigned int flags )
 797 {
 798 }
 799
 800 #endif  /* linux || __FreeBSD__ */
 801
 802 #endif  /* USE_PTRACE */