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 <fcntl.h>
  26 #include <stdio.h>
  27 #include <signal.h>
  28 #include <stdarg.h>
  29 #include <sys/types.h>
  30 #include <sys/wait.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_SYSCALL_H
  38 # include <sys/syscall.h>
  39 #endif
  40 #ifdef HAVE_SYS_UCONTEXT_H
  41 # include <sys/ucontext.h>
  42 #endif
  43 #ifdef HAVE_SYS_THR_H
  44 # include <sys/thr.h>
  45 #endif
  46 #include <unistd.h>
  47
  48 #include "ntstatus.h"
  49 #define WIN32_NO_STATUS
  50 #include "winternl.h"
  51
  52 #include "file.h"
  53 #include "process.h"
  54 #include "thread.h"
  55
  56 #ifdef USE_PTRACE
  57
  58 #ifndef PTRACE_CONT
  59 #define PTRACE_CONT PT_CONTINUE
  60 #endif
  61 #ifndef PTRACE_SINGLESTEP
  62 #define PTRACE_SINGLESTEP PT_STEP
  63 #endif
  64 #ifndef PTRACE_ATTACH
  65 #define PTRACE_ATTACH PT_ATTACH
  66 #endif
  67 #ifndef PTRACE_DETACH
  68 #define PTRACE_DETACH PT_DETACH
  69 #endif
  70 #ifndef PTRACE_PEEKDATA
  71 #define PTRACE_PEEKDATA PT_READ_D
  72 #endif
  73 #ifndef PTRACE_POKEDATA
  74 #define PTRACE_POKEDATA PT_WRITE_D
  75 #endif
  76 #ifndef PTRACE_PEEKUSER
  77 #define PTRACE_PEEKUSER PT_READ_U
  78 #endif
  79 #ifndef PTRACE_POKEUSER
  80 #define PTRACE_POKEUSER PT_WRITE_U
  81 #endif
  82
  83 #ifdef PT_GETDBREGS
  84 #define PTRACE_GETDBREGS PT_GETDBREGS
  85 #endif
  86 #ifdef PT_SETDBREGS
  87 #define PTRACE_SETDBREGS PT_SETDBREGS
  88 #endif
  89
  90 #ifndef HAVE_SYS_PTRACE_H
  91 #define PT_CONTINUE 0
  92 #define PT_ATTACH   1
  93 #define PT_DETACH   2
  94 #define PT_READ_D   3
  95 #define PT_WRITE_D  4
  96 #define PT_STEP     5
  97 static inline int ptrace(int req, ...) { errno = EPERM; return -1; /*FAIL*/ }
  98 #endif  /* HAVE_SYS_PTRACE_H */
  99
 100 #ifndef __WALL
 101 #define __WALL 0
 102 #endif
 103
 104 /* handle a status returned by waitpid */
 105 static int handle_child_status( struct thread *thread, int pid, int status, int want_sig )
 106 {
 107     if (WIFSTOPPED(status))
 108     {
 109         int sig = WSTOPSIG(status);
 110         if (debug_level && thread)
 111             fprintf( stderr, "%04x: *signal* signal=%d\n", thread->id, sig );
 112         if (sig != want_sig)
 113         {
 114             /* ignore other signals for now */
 115             ptrace( PTRACE_CONT, pid, (caddr_t)1, sig );
 116         }
 117         return sig;
 118     }
 119     if (thread && (WIFSIGNALED(status) || WIFEXITED(status)))
 120     {
 121         thread->unix_pid = -1;
 122         thread->unix_tid = -1;
 123         if (debug_level)
 124         {
 125             if (WIFSIGNALED(status))
 126                 fprintf( stderr, "%04x: *exited* signal=%d\n",
 127                          thread->id, WTERMSIG(status) );
 128             else
 129                 fprintf( stderr, "%04x: *exited* status=%d\n",
 130                          thread->id, WEXITSTATUS(status) );
 131         }
 132     }
 133     return 0;
 134 }
 135
 136 /* handle a SIGCHLD signal */
 137 void sigchld_callback(void)
 138 {
 139     int pid, status;
 140
 141     for (;;)
 142     {
 143         if (!(pid = waitpid( -1, &status, WUNTRACED | WNOHANG | __WALL ))) break;
 144         if (pid != -1)
 145         {
 146             struct thread *thread = get_thread_from_tid( pid );
 147             if (!thread) thread = get_thread_from_pid( pid );
 148             handle_child_status( thread, pid, status, -1 );
 149         }
 150         else break;
 151     }
 152 }
 153
 154 /* return the Unix pid to use in ptrace calls for a given process */
 155 static int get_ptrace_pid( struct thread *thread )
 156 {
 157 #ifdef linux  /* linux always uses thread id */
 158     if (thread->unix_tid != -1) return thread->unix_tid;
 159 #endif
 160     return thread->unix_pid;
 161 }
 162
 163 /* return the Unix tid to use in ptrace calls for a given thread */
 164 static int get_ptrace_tid( struct thread *thread )
 165 {
 166     if (thread->unix_tid != -1) return thread->unix_tid;
 167     return thread->unix_pid;
 168 }
 169
 170 /* wait for a ptraced child to get a certain signal */
 171 static int waitpid_thread( struct thread *thread, int signal )
 172 {
 173     int res, status;
 174
 175     start_watchdog();
 176     for (;;)
 177     {
 178         if ((res = waitpid( get_ptrace_pid(thread), &status, WUNTRACED | __WALL )) == -1)
 179         {
 180             if (errno == EINTR)
 181             {
 182                 if (!watchdog_triggered()) continue;
 183                 if (debug_level) fprintf( stderr, "%04x: *watchdog* waitpid aborted\n", thread->id );
 184             }
 185             else if (errno == ECHILD)  /* must have died */
 186             {
 187                 thread->unix_pid = -1;
 188                 thread->unix_tid = -1;
 189             }
 190             else perror( "waitpid" );
 191             stop_watchdog();
 192             return 0;
 193         }
 194         res = handle_child_status( thread, res, status, signal );
 195         if (!res || res == signal) break;
 196     }
 197     stop_watchdog();
 198     return (thread->unix_pid != -1);
 199 }
 200
 201 /* send a signal to a specific thread */
 202 static inline int tkill( int tgid, int pid, int sig )
 203 {
 204 #ifdef __linux__
 205     int ret = syscall( __NR_tgkill, tgid, pid, sig );
 206     if (ret < 0 && errno == ENOSYS) ret = syscall( __NR_tkill, pid, sig );
 207     return ret;
 208 #elif (defined(__FreeBSD__) || defined (__FreeBSD_kernel__)) && defined(HAVE_THR_KILL2)
 209     return thr_kill2( tgid, pid, sig );
 210 #else
 211     errno = ENOSYS;
 212     return -1;
 213 #endif
 214 }
 215
 216 /* initialize the process tracing mechanism */
 217 void init_tracing_mechanism(void)
 218 {
 219     /* no initialization needed for ptrace */
 220 }
 221
 222 /* initialize the per-process tracing mechanism */
 223 void init_process_tracing( struct process *process )
 224 {
 225     /* ptrace setup is done on-demand */
 226 }
 227
 228 /* terminate the per-process tracing mechanism */
 229 void finish_process_tracing( struct process *process )
 230 {
 231 }
 232
 233 /* send a Unix signal to a specific thread */
 234 int send_thread_signal( struct thread *thread, int sig )
 235 {
 236     int ret = -1;
 237
 238     if (thread->unix_pid != -1)
 239     {
 240         if (thread->unix_tid != -1)
 241         {
 242             ret = tkill( thread->unix_pid, thread->unix_tid, sig );
 243             if (ret == -1 && errno == ENOSYS) ret = kill( thread->unix_pid, sig );
 244         }
 245         else ret = kill( thread->unix_pid, sig );
 246
 247         if (ret == -1 && errno == ESRCH) /* thread got killed */
 248         {
 249             thread->unix_pid = -1;
 250             thread->unix_tid = -1;
 251         }
 252     }
 253     if (debug_level && ret != -1)
 254         fprintf( stderr, "%04x: *sent signal* signal=%d\n", thread->id, sig );
 255     return (ret != -1);
 256 }
 257
 258 /* resume a thread after we have used ptrace on it */
 259 static void resume_after_ptrace( struct thread *thread )
 260 {
 261     if (thread->unix_pid == -1) return;
 262     if (ptrace( PTRACE_DETACH, get_ptrace_pid(thread), (caddr_t)1, 0 ) == -1)
 263     {
 264         if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1;  /* thread got killed */
 265     }
 266 }
 267
 268 /* suspend a thread to allow using ptrace on it */
 269 /* you must do a resume_after_ptrace when finished with the thread */
 270 static int suspend_for_ptrace( struct thread *thread )
 271 {
 272     /* can't stop a thread while initialisation is in progress */
 273     if (thread->unix_pid == -1 || !is_process_init_done(thread->process)) goto error;
 274
 275     /* this may fail if the client is already being debugged */
 276     if (ptrace( PTRACE_ATTACH, get_ptrace_pid(thread), 0, 0 ) == -1)
 277     {
 278         if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1;  /* thread got killed */
 279         goto error;
 280     }
 281     if (waitpid_thread( thread, SIGSTOP )) return 1;
 282     resume_after_ptrace( thread );
 283  error:
 284     set_error( STATUS_ACCESS_DENIED );
 285     return 0;
 286 }
 287
 288 /* read a long from a thread address space */
 289 static int read_thread_long( struct thread *thread, void *addr, unsigned long *data )
 290 {
 291     errno = 0;
 292     *data = ptrace( PTRACE_PEEKDATA, get_ptrace_pid(thread), (caddr_t)addr, 0 );
 293     if ( *data == -1 && errno)
 294     {
 295         file_set_error();
 296         return -1;
 297     }
 298     return 0;
 299 }
 300
 301 static int read_thread_int( struct thread *thread, void *addr, unsigned int *data )
 302 {
 303     unsigned long long_data;
 304     int ret;
 305
 306     ret = read_thread_long( thread, addr, &long_data );
 307     *data = long_data;
 308     return ret;
 309 }
 310
 311 /* write a long to a thread address space */
 312 static long write_thread_long( struct thread *thread, void *addr, unsigned long data, unsigned long mask )
 313 {
 314     unsigned long old_data;
 315     int res;
 316
 317     if (mask != ~0ul)
 318     {
 319         if (read_thread_long( thread, addr, &old_data ) == -1) return -1;
 320         data = (data & mask) | (old_data & ~mask);
 321     }
 322     if ((res = ptrace( PTRACE_POKEDATA, get_ptrace_pid(thread), (caddr_t)addr, data )) == -1)
 323         file_set_error();
 324     return res;
 325 }
 326
 327 /* return a thread of the process suitable for ptracing */
 328 static struct thread *get_ptrace_thread( struct process *process )
 329 {
 330     struct thread *thread;
 331
 332     LIST_FOR_EACH_ENTRY( thread, &process->thread_list, struct thread, proc_entry )
 333     {
 334         if (thread->unix_pid != -1) return thread;
 335     }
 336     set_error( STATUS_PROCESS_IS_TERMINATING );  /* process is dead */
 337     return NULL;
 338 }
 339
 340 /* read data from a process memory space */
 341 int read_process_memory( struct process *process, client_ptr_t ptr, data_size_t size, char *dest )
 342 {
 343     struct thread *thread = get_ptrace_thread( process );
 344     unsigned int first_offset, last_offset, len;
 345     unsigned long data, *addr;
 346
 347     if (!thread) return 0;
 348
 349     if ((unsigned long)ptr != ptr)
 350     {
 351         set_error( STATUS_ACCESS_DENIED );
 352         return 0;
 353     }
 354
 355     first_offset = ptr % sizeof(long);
 356     last_offset = (size + first_offset) % sizeof(long);
 357     if (!last_offset) last_offset = sizeof(long);
 358
 359     addr = (unsigned long *)(unsigned long)(ptr - first_offset);
 360     len = (size + first_offset + sizeof(long) - 1) / sizeof(long);
 361
 362     if (suspend_for_ptrace( thread ))
 363     {
 364         if (len > 3)  /* /proc/pid/mem should be faster for large sizes */
 365         {
 366             char procmem[24];
 367             int fd;
 368
 369             snprintf( procmem, sizeof(procmem), "/proc/%u/mem", process->unix_pid );
 370             if ((fd = open( procmem, O_RDONLY )) != -1)
 371             {
 372                 ssize_t ret = pread( fd, dest, size, ptr );
 373                 close( fd );
 374                 if (ret == size)
 375                 {
 376                     len = 0;
 377                     goto done;
 378                 }
 379             }
 380         }
 381
 382         if (len > 1)
 383         {
 384             if (read_thread_long( thread, addr++, &data ) == -1) goto done;
 385             memcpy( dest, (char *)&data + first_offset, sizeof(long) - first_offset );
 386             dest += sizeof(long) - first_offset;
 387             first_offset = 0;
 388             len--;
 389         }
 390
 391         while (len > 1)
 392         {
 393             if (read_thread_long( thread, addr++, &data ) == -1) goto done;
 394             memcpy( dest, &data, sizeof(long) );
 395             dest += sizeof(long);
 396             len--;
 397         }
 398
 399         if (read_thread_long( thread, addr++, &data ) == -1) goto done;
 400         memcpy( dest, (char *)&data + first_offset, last_offset - first_offset );
 401         len--;
 402
 403     done:
 404         resume_after_ptrace( thread );
 405     }
 406     return !len;
 407 }
 408
 409 /* make sure we can write to the whole address range */
 410 /* len is the total size (in longs) */
 411 static int check_process_write_access( struct thread *thread, long *addr, data_size_t len )
 412 {
 413     int page = get_page_size() / sizeof(long);
 414
 415     for (;;)
 416     {
 417         if (write_thread_long( thread, addr, 0, 0 ) == -1) return 0;
 418         if (len <= page) break;
 419         addr += page;
 420         len -= page;
 421     }
 422     return (write_thread_long( thread, addr + len - 1, 0, 0 ) != -1);
 423 }
 424
 425 /* write data to a process memory space */
 426 int write_process_memory( struct process *process, client_ptr_t ptr, data_size_t size, const char *src )
 427 {
 428     struct thread *thread = get_ptrace_thread( process );
 429     int ret = 0;
 430     long data = 0;
 431     data_size_t len;
 432     long *addr;
 433     unsigned long first_mask, first_offset, last_mask, last_offset;
 434
 435     if (!thread) return 0;
 436
 437     if ((unsigned long)ptr != ptr)
 438     {
 439         set_error( STATUS_ACCESS_DENIED );
 440         return 0;
 441     }
 442
 443     /* compute the mask for the first long */
 444     first_mask = ~0;
 445     first_offset = ptr % sizeof(long);
 446     memset( &first_mask, 0, first_offset );
 447
 448     /* compute the mask for the last long */
 449     last_offset = (size + first_offset) % sizeof(long);
 450     if (!last_offset) last_offset = sizeof(long);
 451     last_mask = 0;
 452     memset( &last_mask, 0xff, last_offset );
 453
 454     addr = (long *)(unsigned long)(ptr - first_offset);
 455     len = (size + first_offset + sizeof(long) - 1) / sizeof(long);
 456
 457     if (suspend_for_ptrace( thread ))
 458     {
 459         if (!check_process_write_access( thread, addr, len ))
 460         {
 461             set_error( STATUS_ACCESS_DENIED );
 462             goto done;
 463         }
 464
 465         if (len > 3)
 466         {
 467             char procmem[24];
 468             int fd;
 469
 470             snprintf( procmem, sizeof(procmem), "/proc/%u/mem", process->unix_pid );
 471             if ((fd = open( procmem, O_WRONLY )) != -1)
 472             {
 473                 ssize_t r = pwrite( fd, src, size, ptr );
 474                 close( fd );
 475                 if (r == size)
 476                 {
 477                     ret = 1;
 478                     goto done;
 479                 }
 480             }
 481         }
 482
 483         /* first word is special */
 484         if (len > 1)
 485         {
 486             memcpy( (char *)&data + first_offset, src, sizeof(long) - first_offset );
 487             src += sizeof(long) - first_offset;
 488             if (write_thread_long( thread, addr++, data, first_mask ) == -1) goto done;
 489             first_offset = 0;
 490             len--;
 491         }
 492         else last_mask &= first_mask;
 493
 494         while (len > 1)
 495         {
 496             memcpy( &data, src, sizeof(long) );
 497             src += sizeof(long);
 498             if (write_thread_long( thread, addr++, data, ~0ul ) == -1) goto done;
 499             len--;
 500         }
 501
 502         /* last word is special too */
 503         memcpy( (char *)&data + first_offset, src, last_offset - first_offset );
 504         if (write_thread_long( thread, addr, data, last_mask ) == -1) goto done;
 505         ret = 1;
 506
 507     done:
 508         resume_after_ptrace( thread );
 509     }
 510     return ret;
 511 }
 512
 513 /* retrieve an LDT selector entry */
 514 void get_selector_entry( struct thread *thread, int entry, unsigned int *base,
 515                          unsigned int *limit, unsigned char *flags )
 516 {
 517     if (!thread->process->ldt_copy)
 518     {
 519         set_error( STATUS_ACCESS_DENIED );
 520         return;
 521     }
 522     if (entry >= 8192)
 523     {
 524         set_error( STATUS_ACCESS_VIOLATION );
 525         return;
 526     }
 527     if (suspend_for_ptrace( thread ))
 528     {
 529         unsigned int flags_buf;
 530         unsigned long addr = (unsigned long)thread->process->ldt_copy + (entry * 4);
 531
 532         if (read_thread_int( thread, (void *)addr, base ) == -1) goto done;
 533         if (read_thread_int( thread, (void *)(addr + (8192 * 4)), limit ) == -1) goto done;
 534         addr = (unsigned long)thread->process->ldt_copy + (2 * 8192 * 4) + (entry & ~3);
 535         if (read_thread_int( thread, (void *)addr, &flags_buf ) == -1) goto done;
 536         *flags = flags_buf >> (entry & 3) * 8;
 537     done:
 538         resume_after_ptrace( thread );
 539     }
 540 }
 541
 542
 543 #if defined(linux) && (defined(HAVE_SYS_USER_H) || defined(HAVE_ASM_USER_H)) \
 544     && (defined(__i386__) || defined(__x86_64__))
 545
 546 #ifdef HAVE_SYS_USER_H
 547 #include <sys/user.h>
 548 #elif defined(HAVE_ASM_USER_H)
 549 #include <asm/user.h>
 550 #endif
 551
 552 /* debug register offset in struct user */
 553 #define DR_OFFSET(dr) ((((struct user *)0)->u_debugreg) + (dr))
 554
 555 /* initialize registers in new thread if necessary */
 556 void init_thread_context( struct thread *thread )
 557 {
 558     /* Linux doesn't clear all registers, but hopefully enough to avoid spurious breakpoints */
 559     thread->system_regs = 0;
 560 }
 561
 562 /* retrieve the thread x86 registers */
 563 void get_thread_context( struct thread *thread, context_t *context, unsigned int flags )
 564 {
 565     int i, pid = get_ptrace_tid(thread);
 566     long data[8];
 567
 568     /* all other regs are handled on the client side */
 569     assert( flags == SERVER_CTX_DEBUG_REGISTERS );
 570
 571     if (!(thread->system_regs & SERVER_CTX_DEBUG_REGISTERS))
 572     {
 573         /* caller has initialized everything to 0 already, just return */
 574         context->flags |= SERVER_CTX_DEBUG_REGISTERS;
 575         return;
 576     }
 577
 578     if (!suspend_for_ptrace( thread )) return;
 579
 580     for (i = 0; i < 8; i++)
 581     {
 582         if (i == 4 || i == 5) continue;
 583         errno = 0;
 584         data[i] = ptrace( PTRACE_PEEKUSER, pid, DR_OFFSET(i), 0 );
 585         if ((data[i] == -1) && errno)
 586         {
 587             file_set_error();
 588             goto done;
 589         }
 590     }
 591     switch (context->machine)
 592     {
 593     case IMAGE_FILE_MACHINE_I386:
 594         context->debug.i386_regs.dr0 = data[0];
 595         context->debug.i386_regs.dr1 = data[1];
 596         context->debug.i386_regs.dr2 = data[2];
 597         context->debug.i386_regs.dr3 = data[3];
 598         context->debug.i386_regs.dr6 = data[6];
 599         context->debug.i386_regs.dr7 = data[7];
 600         break;
 601     case IMAGE_FILE_MACHINE_AMD64:
 602         context->debug.x86_64_regs.dr0 = data[0];
 603         context->debug.x86_64_regs.dr1 = data[1];
 604         context->debug.x86_64_regs.dr2 = data[2];
 605         context->debug.x86_64_regs.dr3 = data[3];
 606         context->debug.x86_64_regs.dr6 = data[6];
 607         context->debug.x86_64_regs.dr7 = data[7];
 608         break;
 609     default:
 610         set_error( STATUS_INVALID_PARAMETER );
 611         goto done;
 612     }
 613     context->flags |= SERVER_CTX_DEBUG_REGISTERS;
 614 done:
 615     resume_after_ptrace( thread );
 616 }
 617
 618 /* set the thread x86 registers */
 619 void set_thread_context( struct thread *thread, const context_t *context, unsigned int flags )
 620 {
 621     int pid = get_ptrace_tid( thread );
 622
 623     /* all other regs are handled on the client side */
 624     assert( flags == SERVER_CTX_DEBUG_REGISTERS );
 625
 626     if (!suspend_for_ptrace( thread )) return;
 627
 628     switch (context->machine)
 629     {
 630     case IMAGE_FILE_MACHINE_I386:
 631         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), 0 ) == -1) goto error;
 632         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(0), context->debug.i386_regs.dr0 ) == -1) goto error;
 633         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(1), context->debug.i386_regs.dr1 ) == -1) goto error;
 634         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(2), context->debug.i386_regs.dr2 ) == -1) goto error;
 635         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(3), context->debug.i386_regs.dr3 ) == -1) goto error;
 636         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(6), context->debug.i386_regs.dr6 ) == -1) goto error;
 637         /* Linux 2.6.33+ needs enable bits set briefly to update value returned by PEEKUSER later */
 638         ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->debug.i386_regs.dr7 | 0x55 );
 639         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->debug.i386_regs.dr7 ) == -1) goto error;
 640         thread->system_regs |= SERVER_CTX_DEBUG_REGISTERS;
 641         break;
 642     case IMAGE_FILE_MACHINE_AMD64:
 643         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), 0 ) == -1) goto error;
 644         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(0), context->debug.x86_64_regs.dr0 ) == -1) goto error;
 645         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(1), context->debug.x86_64_regs.dr1 ) == -1) goto error;
 646         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(2), context->debug.x86_64_regs.dr2 ) == -1) goto error;
 647         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(3), context->debug.x86_64_regs.dr3 ) == -1) goto error;
 648         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(6), context->debug.x86_64_regs.dr6 ) == -1) goto error;
 649         ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->debug.x86_64_regs.dr7 | 0x55 );
 650         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->debug.x86_64_regs.dr7 ) == -1) goto error;
 651         thread->system_regs |= SERVER_CTX_DEBUG_REGISTERS;
 652         break;
 653     default:
 654         set_error( STATUS_INVALID_PARAMETER );
 655     }
 656     resume_after_ptrace( thread );
 657     return;
 658  error:
 659     file_set_error();
 660     resume_after_ptrace( thread );
 661 }
 662
 663 #elif defined(__i386__) && defined(PTRACE_GETDBREGS) && defined(PTRACE_SETDBREGS) && \
 664     (defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__OpenBSD__) || defined(__NetBSD__) || defined(__DragonFly__))
 665
 666 #include <machine/reg.h>
 667
 668 /* initialize registers in new thread if necessary */
 669 void init_thread_context( struct thread *thread )
 670 {
 671     if (!(thread->system_regs & SERVER_CTX_DEBUG_REGISTERS)) return;
 672
 673     /* FreeBSD doesn't clear the debug registers in new threads */
 674     if (suspend_for_ptrace( thread ))
 675     {
 676         struct dbreg dbregs;
 677
 678         memset( &dbregs, 0, sizeof(dbregs) );
 679         ptrace( PTRACE_SETDBREGS, get_ptrace_tid( thread ), (caddr_t)&dbregs, 0 );
 680         resume_after_ptrace( thread );
 681     }
 682     thread->system_regs = 0;
 683 }
 684
 685 /* retrieve the thread x86 registers */
 686 void get_thread_context( struct thread *thread, context_t *context, unsigned int flags )
 687 {
 688     int pid = get_ptrace_tid(thread);
 689     struct dbreg dbregs;
 690
 691     /* all other regs are handled on the client side */
 692     assert( flags == SERVER_CTX_DEBUG_REGISTERS );
 693
 694     if (!suspend_for_ptrace( thread )) return;
 695
 696     if (ptrace( PTRACE_GETDBREGS, pid, (caddr_t) &dbregs, 0 ) == -1) file_set_error();
 697     else
 698     {
 699 #ifdef DBREG_DRX
 700         /* needed for FreeBSD, the structure fields have changed under 5.x */
 701         context->debug.i386_regs.dr0 = DBREG_DRX((&dbregs), 0);
 702         context->debug.i386_regs.dr1 = DBREG_DRX((&dbregs), 1);
 703         context->debug.i386_regs.dr2 = DBREG_DRX((&dbregs), 2);
 704         context->debug.i386_regs.dr3 = DBREG_DRX((&dbregs), 3);
 705         context->debug.i386_regs.dr6 = DBREG_DRX((&dbregs), 6);
 706         context->debug.i386_regs.dr7 = DBREG_DRX((&dbregs), 7);
 707 #elif defined(__NetBSD__)
 708         context->debug.i386_regs.dr0 = dbregs.dr[0];
 709         context->debug.i386_regs.dr1 = dbregs.dr[1];
 710         context->debug.i386_regs.dr2 = dbregs.dr[2];
 711         context->debug.i386_regs.dr3 = dbregs.dr[3];
 712         context->debug.i386_regs.dr6 = dbregs.dr[6];
 713         context->debug.i386_regs.dr7 = dbregs.dr[7];
 714 #else
 715         context->debug.i386_regs.dr0 = dbregs.dr0;
 716         context->debug.i386_regs.dr1 = dbregs.dr1;
 717         context->debug.i386_regs.dr2 = dbregs.dr2;
 718         context->debug.i386_regs.dr3 = dbregs.dr3;
 719         context->debug.i386_regs.dr6 = dbregs.dr6;
 720         context->debug.i386_regs.dr7 = dbregs.dr7;
 721 #endif
 722         context->flags |= SERVER_CTX_DEBUG_REGISTERS;
 723     }
 724     resume_after_ptrace( thread );
 725 }
 726
 727 /* set the thread x86 registers */
 728 void set_thread_context( struct thread *thread, const context_t *context, unsigned int flags )
 729 {
 730     int pid = get_ptrace_tid(thread);
 731     struct dbreg dbregs;
 732
 733     /* all other regs are handled on the client side */
 734     assert( flags == SERVER_CTX_DEBUG_REGISTERS );
 735
 736     if (!suspend_for_ptrace( thread )) return;
 737
 738 #ifdef DBREG_DRX
 739     /* needed for FreeBSD, the structure fields have changed under 5.x */
 740     DBREG_DRX((&dbregs), 0) = context->debug.i386_regs.dr0;
 741     DBREG_DRX((&dbregs), 1) = context->debug.i386_regs.dr1;
 742     DBREG_DRX((&dbregs), 2) = context->debug.i386_regs.dr2;
 743     DBREG_DRX((&dbregs), 3) = context->debug.i386_regs.dr3;
 744     DBREG_DRX((&dbregs), 4) = 0;
 745     DBREG_DRX((&dbregs), 5) = 0;
 746     DBREG_DRX((&dbregs), 6) = context->debug.i386_regs.dr6;
 747     DBREG_DRX((&dbregs), 7) = context->debug.i386_regs.dr7;
 748 #elif defined(__NetBSD__)
 749     dbregs.dr[0] = context->debug.i386_regs.dr0;
 750     dbregs.dr[1] = context->debug.i386_regs.dr1;
 751     dbregs.dr[2] = context->debug.i386_regs.dr2;
 752     dbregs.dr[3] = context->debug.i386_regs.dr3;
 753     dbregs.dr[4] = 0;
 754     dbregs.dr[5] = 0;
 755     dbregs.dr[6] = context->debug.i386_regs.dr6;
 756     dbregs.dr[7] = context->debug.i386_regs.dr7;
 757 #else
 758     dbregs.dr0 = context->debug.i386_regs.dr0;
 759     dbregs.dr1 = context->debug.i386_regs.dr1;
 760     dbregs.dr2 = context->debug.i386_regs.dr2;
 761     dbregs.dr3 = context->debug.i386_regs.dr3;
 762     dbregs.dr4 = 0;
 763     dbregs.dr5 = 0;
 764     dbregs.dr6 = context->debug.i386_regs.dr6;
 765     dbregs.dr7 = context->debug.i386_regs.dr7;
 766 #endif
 767     if (ptrace( PTRACE_SETDBREGS, pid, (caddr_t)&dbregs, 0 ) != -1)
 768     {
 769         thread->system_regs |= SERVER_CTX_DEBUG_REGISTERS;
 770     }
 771     else file_set_error();
 772
 773     resume_after_ptrace( thread );
 774 }
 775
 776 #else  /* linux || __FreeBSD__ */
 777
 778 /* initialize registers in new thread if necessary */
 779 void init_thread_context( struct thread *thread )
 780 {
 781 }
 782
 783 /* retrieve the thread x86 registers */
 784 void get_thread_context( struct thread *thread, context_t *context, unsigned int flags )
 785 {
 786 }
 787
 788 /* set the thread x86 debug registers */
 789 void set_thread_context( struct thread *thread, const context_t *context, unsigned int flags )
 790 {
 791 }
 792
 793 #endif  /* linux || __FreeBSD__ */
 794
 795 #endif  /* USE_PTRACE */