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_THR_H
  41 # include <sys/ucontext.h>
  42 # include <sys/thr.h>
  43 #endif
  44 #include <unistd.h>
  45
  46 #include "ntstatus.h"
  47 #define WIN32_NO_STATUS
  48 #include "winternl.h"
  49
  50 #include "file.h"
  51 #include "process.h"
  52 #include "thread.h"
  53
  54 #ifdef USE_PTRACE
  55
  56 #ifndef PTRACE_CONT
  57 #define PTRACE_CONT PT_CONTINUE
  58 #endif
  59 #ifndef PTRACE_SINGLESTEP
  60 #define PTRACE_SINGLESTEP PT_STEP
  61 #endif
  62 #ifndef PTRACE_ATTACH
  63 #define PTRACE_ATTACH PT_ATTACH
  64 #endif
  65 #ifndef PTRACE_DETACH
  66 #define PTRACE_DETACH PT_DETACH
  67 #endif
  68 #ifndef PTRACE_PEEKDATA
  69 #define PTRACE_PEEKDATA PT_READ_D
  70 #endif
  71 #ifndef PTRACE_POKEDATA
  72 #define PTRACE_POKEDATA PT_WRITE_D
  73 #endif
  74 #ifndef PTRACE_PEEKUSER
  75 #define PTRACE_PEEKUSER PT_READ_U
  76 #endif
  77 #ifndef PTRACE_POKEUSER
  78 #define PTRACE_POKEUSER PT_WRITE_U
  79 #endif
  80
  81 #ifdef PT_GETDBREGS
  82 #define PTRACE_GETDBREGS PT_GETDBREGS
  83 #endif
  84 #ifdef PT_SETDBREGS
  85 #define PTRACE_SETDBREGS PT_SETDBREGS
  86 #endif
  87
  88 #ifndef HAVE_SYS_PTRACE_H
  89 #define PT_CONTINUE 0
  90 #define PT_ATTACH   1
  91 #define PT_DETACH   2
  92 #define PT_READ_D   3
  93 #define PT_WRITE_D  4
  94 #define PT_STEP     5
  95 static inline int ptrace(int req, ...) { errno = EPERM; return -1; /*FAIL*/ }
  96 #endif  /* HAVE_SYS_PTRACE_H */
  97
  98 /* handle a status returned by wait4 */
  99 static int handle_child_status( struct thread *thread, int pid, int status, int want_sig )
 100 {
 101     if (WIFSTOPPED(status))
 102     {
 103         int sig = WSTOPSIG(status);
 104         if (debug_level && thread)
 105             fprintf( stderr, "%04x: *signal* signal=%d\n", thread->id, sig );
 106         if (sig != want_sig)
 107         {
 108             /* ignore other signals for now */
 109             ptrace( PTRACE_CONT, pid, (caddr_t)1, sig );
 110         }
 111         return sig;
 112     }
 113     if (thread && (WIFSIGNALED(status) || WIFEXITED(status)))
 114     {
 115         thread->unix_pid = -1;
 116         thread->unix_tid = -1;
 117         if (debug_level)
 118         {
 119             if (WIFSIGNALED(status))
 120                 fprintf( stderr, "%04x: *exited* signal=%d\n",
 121                          thread->id, WTERMSIG(status) );
 122             else
 123                 fprintf( stderr, "%04x: *exited* status=%d\n",
 124                          thread->id, WEXITSTATUS(status) );
 125         }
 126     }
 127     return 0;
 128 }
 129
 130 /* wait4 wrapper to handle missing __WALL flag in older kernels */
 131 static inline pid_t wait4_wrapper( pid_t pid, int *status, int options, struct rusage *usage )
 132 {
 133 #ifdef __WALL
 134     static int wall_flag = __WALL;
 135
 136     for (;;)
 137     {
 138         pid_t ret = wait4( pid, status, options | wall_flag, usage );
 139         if (ret != -1 || !wall_flag || errno != EINVAL) return ret;
 140         wall_flag = 0;
 141     }
 142 #else
 143     return wait4( pid, status, options, usage );
 144 #endif
 145 }
 146
 147 /* handle a SIGCHLD signal */
 148 void sigchld_callback(void)
 149 {
 150     int pid, status;
 151
 152     for (;;)
 153     {
 154         if (!(pid = wait4_wrapper( -1, &status, WUNTRACED | WNOHANG, NULL ))) break;
 155         if (pid != -1)
 156         {
 157             struct thread *thread = get_thread_from_tid( pid );
 158             if (!thread) thread = get_thread_from_pid( pid );
 159             handle_child_status( thread, pid, status, -1 );
 160         }
 161         else break;
 162     }
 163 }
 164
 165 /* return the Unix pid to use in ptrace calls for a given process */
 166 static int get_ptrace_pid( struct thread *thread )
 167 {
 168 #ifdef linux  /* linux always uses thread id */
 169     if (thread->unix_tid != -1) return thread->unix_tid;
 170 #endif
 171     return thread->unix_pid;
 172 }
 173
 174 /* return the Unix tid to use in ptrace calls for a given thread */
 175 static int get_ptrace_tid( struct thread *thread )
 176 {
 177     if (thread->unix_tid != -1) return thread->unix_tid;
 178     return thread->unix_pid;
 179 }
 180
 181 /* wait for a ptraced child to get a certain signal */
 182 static int wait4_thread( struct thread *thread, int signal )
 183 {
 184     int res, status;
 185
 186     start_watchdog();
 187     for (;;)
 188     {
 189         if ((res = wait4_wrapper( get_ptrace_pid(thread), &status, WUNTRACED, NULL )) == -1)
 190         {
 191             if (errno == EINTR)
 192             {
 193                 if (!watchdog_triggered()) continue;
 194                 if (debug_level) fprintf( stderr, "%04x: *watchdog* wait4 aborted\n", thread->id );
 195             }
 196             else if (errno == ECHILD)  /* must have died */
 197             {
 198                 thread->unix_pid = -1;
 199                 thread->unix_tid = -1;
 200             }
 201             else perror( "wait4" );
 202             stop_watchdog();
 203             return 0;
 204         }
 205         res = handle_child_status( thread, res, status, signal );
 206         if (!res || res == signal) break;
 207     }
 208     stop_watchdog();
 209     return (thread->unix_pid != -1);
 210 }
 211
 212 /* send a signal to a specific thread */
 213 static inline int tkill( int tgid, int pid, int sig )
 214 {
 215 #ifdef __linux__
 216     int ret = -ENOSYS;
 217 # ifdef __i386__
 218     ret = syscall(270 /*SYS_tgkill*/, tgid, pid, sig);
 219     if (ret < 0 && errno == -ENOSYS)
 220         ret = syscall(238 /*SYS_tkill*/, pid, sig);
 221     return ret;
 222 # elif defined(__x86_64__)
 223     return syscall(200 /*SYS_tkill*/, pid, sig);
 224 # endif
 225     if (ret >= 0) return ret;
 226     errno = -ret;
 227     return -1;
 228 #elif defined(__FreeBSD__) && defined(HAVE_THR_KILL2)
 229     return thr_kill2( tgid, pid, sig );
 230 #else
 231     errno = ENOSYS;
 232     return -1;
 233 #endif
 234 }
 235
 236 /* initialize the process tracing mechanism */
 237 void init_tracing_mechanism(void)
 238 {
 239     /* no initialization needed for ptrace */
 240 }
 241
 242 /* initialize the per-process tracing mechanism */
 243 void init_process_tracing( struct process *process )
 244 {
 245     /* ptrace setup is done on-demand */
 246 }
 247
 248 /* terminate the per-process tracing mechanism */
 249 void finish_process_tracing( struct process *process )
 250 {
 251 }
 252
 253 /* send a Unix signal to a specific thread */
 254 int send_thread_signal( struct thread *thread, int sig )
 255 {
 256     int ret = -1;
 257
 258     if (thread->unix_pid != -1)
 259     {
 260         if (thread->unix_tid != -1)
 261         {
 262             ret = tkill( thread->unix_pid, thread->unix_tid, sig );
 263             if (ret == -1 && errno == ENOSYS) ret = kill( thread->unix_pid, sig );
 264         }
 265         else ret = kill( thread->unix_pid, sig );
 266
 267         if (ret == -1 && errno == ESRCH) /* thread got killed */
 268         {
 269             thread->unix_pid = -1;
 270             thread->unix_tid = -1;
 271         }
 272     }
 273     if (debug_level && ret != -1)
 274         fprintf( stderr, "%04x: *sent signal* signal=%d\n", thread->id, sig );
 275     return (ret != -1);
 276 }
 277
 278 /* resume a thread after we have used ptrace on it */
 279 static void resume_after_ptrace( struct thread *thread )
 280 {
 281     if (thread->unix_pid == -1) return;
 282     if (ptrace( PTRACE_DETACH, get_ptrace_pid(thread), (caddr_t)1, 0 ) == -1)
 283     {
 284         if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1;  /* thread got killed */
 285     }
 286 }
 287
 288 /* suspend a thread to allow using ptrace on it */
 289 /* you must do a resume_after_ptrace when finished with the thread */
 290 static int suspend_for_ptrace( struct thread *thread )
 291 {
 292     /* can't stop a thread while initialisation is in progress */
 293     if (thread->unix_pid == -1 || !is_process_init_done(thread->process)) goto error;
 294
 295     /* this may fail if the client is already being debugged */
 296     if (ptrace( PTRACE_ATTACH, get_ptrace_pid(thread), 0, 0 ) == -1)
 297     {
 298         if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1;  /* thread got killed */
 299         goto error;
 300     }
 301     if (wait4_thread( thread, SIGSTOP )) return 1;
 302     resume_after_ptrace( thread );
 303  error:
 304     set_error( STATUS_ACCESS_DENIED );
 305     return 0;
 306 }
 307
 308 /* read a long from a thread address space */
 309 static long read_thread_long( struct thread *thread, long *addr, long *data )
 310 {
 311     errno = 0;
 312     *data = ptrace( PTRACE_PEEKDATA, get_ptrace_pid(thread), (caddr_t)addr, 0 );
 313     if ( *data == -1 && errno)
 314     {
 315         file_set_error();
 316         return -1;
 317     }
 318     return 0;
 319 }
 320
 321 /* write a long to a thread address space */
 322 static long write_thread_long( struct thread *thread, long *addr, long data, unsigned long mask )
 323 {
 324     long res;
 325     if (mask != ~0ul)
 326     {
 327         if (read_thread_long( thread, addr, &res ) == -1) return -1;
 328         data = (data & mask) | (res & ~mask);
 329     }
 330     if ((res = ptrace( PTRACE_POKEDATA, get_ptrace_pid(thread), (caddr_t)addr, data )) == -1)
 331         file_set_error();
 332     return res;
 333 }
 334
 335 /* return a thread of the process suitable for ptracing */
 336 static struct thread *get_ptrace_thread( struct process *process )
 337 {
 338     struct thread *thread;
 339
 340     LIST_FOR_EACH_ENTRY( thread, &process->thread_list, struct thread, proc_entry )
 341     {
 342         if (thread->unix_pid != -1) return thread;
 343     }
 344     set_error( STATUS_ACCESS_DENIED );  /* process is dead */
 345     return NULL;
 346 }
 347
 348 /* read data from a process memory space */
 349 int read_process_memory( struct process *process, client_ptr_t ptr, data_size_t size, char *dest )
 350 {
 351     struct thread *thread = get_ptrace_thread( process );
 352     unsigned int first_offset, last_offset, len;
 353     long data, *addr;
 354
 355     if (!thread) return 0;
 356
 357     if ((unsigned long)ptr != ptr)
 358     {
 359         set_error( STATUS_ACCESS_DENIED );
 360         return 0;
 361     }
 362
 363     first_offset = ptr % sizeof(long);
 364     last_offset = (size + first_offset) % sizeof(long);
 365     if (!last_offset) last_offset = sizeof(long);
 366
 367     addr = (long *)(unsigned long)(ptr - first_offset);
 368     len = (size + first_offset + sizeof(long) - 1) / sizeof(long);
 369
 370     if (suspend_for_ptrace( thread ))
 371     {
 372         if (len > 3)  /* /proc/pid/mem should be faster for large sizes */
 373         {
 374             char procmem[24];
 375             int fd;
 376
 377             sprintf( procmem, "/proc/%u/mem", process->unix_pid );
 378             if ((fd = open( procmem, O_RDONLY )) != -1)
 379             {
 380                 ssize_t ret = pread( fd, dest, size, ptr );
 381                 close( fd );
 382                 if (ret == size)
 383                 {
 384                     len = 0;
 385                     goto done;
 386                 }
 387             }
 388         }
 389
 390         if (len > 1)
 391         {
 392             if (read_thread_long( thread, addr++, &data ) == -1) goto done;
 393             memcpy( dest, (char *)&data + first_offset, sizeof(long) - first_offset );
 394             dest += sizeof(long) - first_offset;
 395             first_offset = 0;
 396             len--;
 397         }
 398
 399         while (len > 1)
 400         {
 401             if (read_thread_long( thread, addr++, &data ) == -1) goto done;
 402             memcpy( dest, &data, sizeof(long) );
 403             dest += sizeof(long);
 404             len--;
 405         }
 406
 407         if (read_thread_long( thread, addr++, &data ) == -1) goto done;
 408         memcpy( dest, (char *)&data + first_offset, last_offset - first_offset );
 409         len--;
 410
 411     done:
 412         resume_after_ptrace( thread );
 413     }
 414     return !len;
 415 }
 416
 417 /* make sure we can write to the whole address range */
 418 /* len is the total size (in ints) */
 419 static int check_process_write_access( struct thread *thread, long *addr, data_size_t len )
 420 {
 421     int page = get_page_size() / sizeof(int);
 422
 423     for (;;)
 424     {
 425         if (write_thread_long( thread, addr, 0, 0 ) == -1) return 0;
 426         if (len <= page) break;
 427         addr += page;
 428         len -= page;
 429     }
 430     return (write_thread_long( thread, addr + len - 1, 0, 0 ) != -1);
 431 }
 432
 433 /* write data to a process memory space */
 434 int write_process_memory( struct process *process, client_ptr_t ptr, data_size_t size, const char *src )
 435 {
 436     struct thread *thread = get_ptrace_thread( process );
 437     int ret = 0;
 438     long data = 0;
 439     data_size_t len;
 440     long *addr;
 441     unsigned long first_mask, first_offset, last_mask, last_offset;
 442
 443     if (!thread) return 0;
 444
 445     if ((unsigned long)ptr != ptr)
 446     {
 447         set_error( STATUS_ACCESS_DENIED );
 448         return 0;
 449     }
 450
 451     /* compute the mask for the first long */
 452     first_mask = ~0;
 453     first_offset = ptr % sizeof(long);
 454     memset( &first_mask, 0, first_offset );
 455
 456     /* compute the mask for the last long */
 457     last_offset = (size + first_offset) % sizeof(long);
 458     if (!last_offset) last_offset = sizeof(long);
 459     last_mask = 0;
 460     memset( &last_mask, 0xff, last_offset );
 461
 462     addr = (long *)(unsigned long)(ptr - first_offset);
 463     len = (size + first_offset + sizeof(long) - 1) / sizeof(long);
 464
 465     if (suspend_for_ptrace( thread ))
 466     {
 467         if (!check_process_write_access( thread, addr, len ))
 468         {
 469             set_error( STATUS_ACCESS_DENIED );
 470             goto done;
 471         }
 472         /* first word is special */
 473         if (len > 1)
 474         {
 475             memcpy( (char *)&data + first_offset, src, sizeof(long) - first_offset );
 476             src += sizeof(long) - first_offset;
 477             if (write_thread_long( thread, addr++, data, first_mask ) == -1) goto done;
 478             first_offset = 0;
 479             len--;
 480         }
 481         else last_mask &= first_mask;
 482
 483         while (len > 1)
 484         {
 485             memcpy( &data, src, sizeof(long) );
 486             src += sizeof(long);
 487             if (write_thread_long( thread, addr++, data, ~0ul ) == -1) goto done;
 488             len--;
 489         }
 490
 491         /* last word is special too */
 492         memcpy( (char *)&data + first_offset, src, last_offset - first_offset );
 493         if (write_thread_long( thread, addr, data, last_mask ) == -1) goto done;
 494         ret = 1;
 495
 496     done:
 497         resume_after_ptrace( thread );
 498     }
 499     return ret;
 500 }
 501
 502 /* retrieve an LDT selector entry */
 503 void get_selector_entry( struct thread *thread, int entry, unsigned int *base,
 504                          unsigned int *limit, unsigned char *flags )
 505 {
 506     if (!thread->process->ldt_copy)
 507     {
 508         set_error( STATUS_ACCESS_DENIED );
 509         return;
 510     }
 511     if (entry >= 8192)
 512     {
 513         set_error( STATUS_ACCESS_VIOLATION );
 514         return;
 515     }
 516     if (suspend_for_ptrace( thread ))
 517     {
 518         unsigned char flags_buf[sizeof(long)];
 519         long *addr = (long *)(unsigned long)thread->process->ldt_copy + entry;
 520         if (read_thread_long( thread, addr, (long *)base ) == -1) goto done;
 521         if (read_thread_long( thread, addr + 8192, (long *)limit ) == -1) goto done;
 522         addr = (long *)(unsigned long)thread->process->ldt_copy + 2*8192 + (entry / sizeof(long));
 523         if (read_thread_long( thread, addr, (long *)flags_buf ) == -1) goto done;
 524         *flags = flags_buf[entry % sizeof(long)];
 525     done:
 526         resume_after_ptrace( thread );
 527     }
 528 }
 529
 530
 531 #if defined(linux) && (defined(__i386__) || defined(__x86_64__))
 532
 533 #ifdef HAVE_SYS_USER_H
 534 # include <sys/user.h>
 535 #endif
 536
 537 /* debug register offset in struct user */
 538 #define DR_OFFSET(dr) ((((struct user *)0)->u_debugreg) + (dr))
 539
 540 /* retrieve the thread x86 registers */
 541 void get_thread_context( struct thread *thread, context_t *context, unsigned int flags )
 542 {
 543     int i, pid = get_ptrace_tid(thread);
 544     long data[8];
 545
 546     /* all other regs are handled on the client side */
 547     assert( flags == SERVER_CTX_DEBUG_REGISTERS );
 548
 549     if (!suspend_for_ptrace( thread )) return;
 550
 551     for (i = 0; i < 8; i++)
 552     {
 553         if (i == 4 || i == 5) continue;
 554         errno = 0;
 555         data[i] = ptrace( PTRACE_PEEKUSER, pid, DR_OFFSET(i), 0 );
 556         if ((data[i] == -1) && errno)
 557         {
 558             file_set_error();
 559             goto done;
 560         }
 561     }
 562     switch (context->cpu)
 563     {
 564     case CPU_x86:
 565         context->debug.i386_regs.dr0 = data[0];
 566         context->debug.i386_regs.dr1 = data[1];
 567         context->debug.i386_regs.dr2 = data[2];
 568         context->debug.i386_regs.dr3 = data[3];
 569         context->debug.i386_regs.dr6 = data[6];
 570         context->debug.i386_regs.dr7 = data[7];
 571         break;
 572     case CPU_x86_64:
 573         context->debug.x86_64_regs.dr0 = data[0];
 574         context->debug.x86_64_regs.dr1 = data[1];
 575         context->debug.x86_64_regs.dr2 = data[2];
 576         context->debug.x86_64_regs.dr3 = data[3];
 577         context->debug.x86_64_regs.dr6 = data[6];
 578         context->debug.x86_64_regs.dr7 = data[7];
 579         break;
 580     default:
 581         set_error( STATUS_INVALID_PARAMETER );
 582         goto done;
 583     }
 584     context->flags |= SERVER_CTX_DEBUG_REGISTERS;
 585 done:
 586     resume_after_ptrace( thread );
 587 }
 588
 589 /* set the thread x86 registers */
 590 void set_thread_context( struct thread *thread, const context_t *context, unsigned int flags )
 591 {
 592     int pid = get_ptrace_tid( thread );
 593
 594     /* all other regs are handled on the client side */
 595     assert( flags == SERVER_CTX_DEBUG_REGISTERS );
 596
 597     if (!suspend_for_ptrace( thread )) return;
 598
 599     switch (context->cpu)
 600     {
 601     case CPU_x86:
 602         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(0), context->debug.i386_regs.dr0 ) == -1) goto error;
 603         if (thread->context) thread->context->debug.i386_regs.dr0 = context->debug.i386_regs.dr0;
 604         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(1), context->debug.i386_regs.dr1 ) == -1) goto error;
 605         if (thread->context) thread->context->debug.i386_regs.dr1 = context->debug.i386_regs.dr1;
 606         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(2), context->debug.i386_regs.dr2 ) == -1) goto error;
 607         if (thread->context) thread->context->debug.i386_regs.dr2 = context->debug.i386_regs.dr2;
 608         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(3), context->debug.i386_regs.dr3 ) == -1) goto error;
 609         if (thread->context) thread->context->debug.i386_regs.dr3 = context->debug.i386_regs.dr3;
 610         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(6), context->debug.i386_regs.dr6 ) == -1) goto error;
 611         if (thread->context) thread->context->debug.i386_regs.dr6 = context->debug.i386_regs.dr6;
 612         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->debug.i386_regs.dr7 ) == -1) goto error;
 613         if (thread->context) thread->context->debug.i386_regs.dr7 = context->debug.i386_regs.dr7;
 614         break;
 615     case CPU_x86_64:
 616         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(0), context->debug.x86_64_regs.dr0 ) == -1) goto error;
 617         if (thread->context) thread->context->debug.x86_64_regs.dr0 = context->debug.x86_64_regs.dr0;
 618         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(1), context->debug.x86_64_regs.dr1 ) == -1) goto error;
 619         if (thread->context) thread->context->debug.x86_64_regs.dr1 = context->debug.x86_64_regs.dr1;
 620         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(2), context->debug.x86_64_regs.dr2 ) == -1) goto error;
 621         if (thread->context) thread->context->debug.x86_64_regs.dr2 = context->debug.x86_64_regs.dr2;
 622         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(3), context->debug.x86_64_regs.dr3 ) == -1) goto error;
 623         if (thread->context) thread->context->debug.x86_64_regs.dr3 = context->debug.x86_64_regs.dr3;
 624         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(6), context->debug.x86_64_regs.dr6 ) == -1) goto error;
 625         if (thread->context) thread->context->debug.x86_64_regs.dr6 = context->debug.x86_64_regs.dr6;
 626         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->debug.x86_64_regs.dr7 ) == -1) goto error;
 627         if (thread->context) thread->context->debug.x86_64_regs.dr7 = context->debug.x86_64_regs.dr7;
 628         break;
 629     default:
 630         set_error( STATUS_INVALID_PARAMETER );
 631     }
 632     resume_after_ptrace( thread );
 633     return;
 634  error:
 635     file_set_error();
 636     resume_after_ptrace( thread );
 637 }
 638
 639 #elif defined(__i386__) && defined(PTRACE_GETDBREGS) && defined(PTRACE_SETDBREGS) && \
 640     (defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__OpenBSD__) || defined(__NetBSD__))
 641
 642 #include <machine/reg.h>
 643
 644 /* retrieve the thread x86 registers */
 645 void get_thread_context( struct thread *thread, context_t *context, unsigned int flags )
 646 {
 647     int pid = get_ptrace_tid(thread);
 648     struct dbreg dbregs;
 649
 650     /* all other regs are handled on the client side */
 651     assert( flags == SERVER_CTX_DEBUG_REGISTERS );
 652
 653     if (!suspend_for_ptrace( thread )) return;
 654
 655     if (ptrace( PTRACE_GETDBREGS, pid, (caddr_t) &dbregs, 0 ) == -1) file_set_error();
 656     else
 657     {
 658 #ifdef DBREG_DRX
 659         /* needed for FreeBSD, the structure fields have changed under 5.x */
 660         context->debug.i386_regs.dr0 = DBREG_DRX((&dbregs), 0);
 661         context->debug.i386_regs.dr1 = DBREG_DRX((&dbregs), 1);
 662         context->debug.i386_regs.dr2 = DBREG_DRX((&dbregs), 2);
 663         context->debug.i386_regs.dr3 = DBREG_DRX((&dbregs), 3);
 664         context->debug.i386_regs.dr6 = DBREG_DRX((&dbregs), 6);
 665         context->debug.i386_regs.dr7 = DBREG_DRX((&dbregs), 7);
 666 #else
 667         context->debug.i386_regs.dr0 = dbregs.dr0;
 668         context->debug.i386_regs.dr1 = dbregs.dr1;
 669         context->debug.i386_regs.dr2 = dbregs.dr2;
 670         context->debug.i386_regs.dr3 = dbregs.dr3;
 671         context->debug.i386_regs.dr6 = dbregs.dr6;
 672         context->debug.i386_regs.dr7 = dbregs.dr7;
 673 #endif
 674         context->flags |= SERVER_CTX_DEBUG_REGISTERS;
 675     }
 676     resume_after_ptrace( thread );
 677 }
 678
 679 /* set the thread x86 registers */
 680 void set_thread_context( struct thread *thread, const context_t *context, unsigned int flags )
 681 {
 682     int pid = get_ptrace_tid(thread);
 683     struct dbreg dbregs;
 684
 685     /* all other regs are handled on the client side */
 686     assert( flags == SERVER_CTX_DEBUG_REGISTERS );
 687
 688     if (!suspend_for_ptrace( thread )) return;
 689
 690 #ifdef DBREG_DRX
 691     /* needed for FreeBSD, the structure fields have changed under 5.x */
 692     DBREG_DRX((&dbregs), 0) = context->debug.i386_regs.dr0;
 693     DBREG_DRX((&dbregs), 1) = context->debug.i386_regs.dr1;
 694     DBREG_DRX((&dbregs), 2) = context->debug.i386_regs.dr2;
 695     DBREG_DRX((&dbregs), 3) = context->debug.i386_regs.dr3;
 696     DBREG_DRX((&dbregs), 4) = 0;
 697     DBREG_DRX((&dbregs), 5) = 0;
 698     DBREG_DRX((&dbregs), 6) = context->debug.i386_regs.dr6;
 699     DBREG_DRX((&dbregs), 7) = context->debug.i386_regs.dr7;
 700 #else
 701     dbregs.dr0 = context->debug.i386_regs.dr0;
 702     dbregs.dr1 = context->debug.i386_regs.dr1;
 703     dbregs.dr2 = context->debug.i386_regs.dr2;
 704     dbregs.dr3 = context->debug.i386_regs.dr3;
 705     dbregs.dr4 = 0;
 706     dbregs.dr5 = 0;
 707     dbregs.dr6 = context->debug.i386_regs.dr6;
 708     dbregs.dr7 = context->debug.i386_regs.dr7;
 709 #endif
 710     if (ptrace( PTRACE_SETDBREGS, pid, (caddr_t) &dbregs, 0 ) == -1) file_set_error();
 711     else if (thread->context)
 712         thread->context->debug.i386_regs = context->debug.i386_regs;  /* update the cached values */
 713     resume_after_ptrace( thread );
 714 }
 715
 716 #else  /* linux || __FreeBSD__ */
 717
 718 /* retrieve the thread x86 registers */
 719 void get_thread_context( struct thread *thread, context_t *context, unsigned int flags )
 720 {
 721 }
 722
 723 /* set the thread x86 debug registers */
 724 void set_thread_context( struct thread *thread, const context_t *context, unsigned int flags )
 725 {
 726 }
 727
 728 #endif  /* linux || __FreeBSD__ */
 729
 730 #endif  /* USE_PTRACE */