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 #ifdef HAVE_SYS_PTRACE_H
  31 # include <sys/ptrace.h>
  32 #endif
  33 #ifdef HAVE_SYS_PARAM_H
  34 # include <sys/param.h>
  35 #endif
  36 #ifdef HAVE_SYS_WAIT_H
  37 # include <sys/wait.h>
  38 #endif
  39 #ifdef HAVE_SYS_SYSCALL_H
  40 # include <sys/syscall.h>
  41 #endif
  42 #ifdef HAVE_SYS_UCONTEXT_H
  43 # include <sys/ucontext.h>
  44 #endif
  45 #ifdef HAVE_SYS_THR_H
  46 # include <sys/thr.h>
  47 #endif
  48 #include <unistd.h>
  49
  50 #include "ntstatus.h"
  51 #define WIN32_NO_STATUS
  52 #include "winternl.h"
  53
  54 #include "file.h"
  55 #include "process.h"
  56 #include "thread.h"
  57
  58 #ifdef USE_PTRACE
  59
  60 #ifndef PTRACE_CONT
  61 #define PTRACE_CONT PT_CONTINUE
  62 #endif
  63 #ifndef PTRACE_SINGLESTEP
  64 #define PTRACE_SINGLESTEP PT_STEP
  65 #endif
  66 #ifndef PTRACE_ATTACH
  67 #define PTRACE_ATTACH PT_ATTACH
  68 #endif
  69 #ifndef PTRACE_DETACH
  70 #define PTRACE_DETACH PT_DETACH
  71 #endif
  72 #ifndef PTRACE_PEEKDATA
  73 #define PTRACE_PEEKDATA PT_READ_D
  74 #endif
  75 #ifndef PTRACE_POKEDATA
  76 #define PTRACE_POKEDATA PT_WRITE_D
  77 #endif
  78 #ifndef PTRACE_PEEKUSER
  79 #define PTRACE_PEEKUSER PT_READ_U
  80 #endif
  81 #ifndef PTRACE_POKEUSER
  82 #define PTRACE_POKEUSER PT_WRITE_U
  83 #endif
  84
  85 #ifdef PT_GETDBREGS
  86 #define PTRACE_GETDBREGS PT_GETDBREGS
  87 #endif
  88 #ifdef PT_SETDBREGS
  89 #define PTRACE_SETDBREGS PT_SETDBREGS
  90 #endif
  91
  92 #ifndef HAVE_SYS_PTRACE_H
  93 #define PT_CONTINUE 0
  94 #define PT_ATTACH   1
  95 #define PT_DETACH   2
  96 #define PT_READ_D   3
  97 #define PT_WRITE_D  4
  98 #define PT_STEP     5
  99 static inline int ptrace(int req, ...) { errno = EPERM; return -1; /*FAIL*/ }
 100 #endif  /* HAVE_SYS_PTRACE_H */
 101
 102 #ifndef __WALL
 103 #define __WALL 0
 104 #endif
 105
 106 /* handle a status returned by waitpid */
 107 static int handle_child_status( struct thread *thread, int pid, int status, int want_sig )
 108 {
 109     if (WIFSTOPPED(status))
 110     {
 111         int sig = WSTOPSIG(status);
 112         if (debug_level && thread)
 113             fprintf( stderr, "%04x: *signal* signal=%d\n", thread->id, sig );
 114         if (sig != want_sig)
 115         {
 116             /* ignore other signals for now */
 117             ptrace( PTRACE_CONT, pid, (caddr_t)1, sig );
 118         }
 119         return sig;
 120     }
 121     if (thread && (WIFSIGNALED(status) || WIFEXITED(status)))
 122     {
 123         thread->unix_pid = -1;
 124         thread->unix_tid = -1;
 125         if (debug_level)
 126         {
 127             if (WIFSIGNALED(status))
 128                 fprintf( stderr, "%04x: *exited* signal=%d\n",
 129                          thread->id, WTERMSIG(status) );
 130             else
 131                 fprintf( stderr, "%04x: *exited* status=%d\n",
 132                          thread->id, WEXITSTATUS(status) );
 133         }
 134     }
 135     return 0;
 136 }
 137
 138 /* handle a SIGCHLD signal */
 139 void sigchld_callback(void)
 140 {
 141     int pid, status;
 142
 143     for (;;)
 144     {
 145         if (!(pid = waitpid( -1, &status, WUNTRACED | WNOHANG | __WALL ))) break;
 146         if (pid != -1)
 147         {
 148             struct thread *thread = get_thread_from_tid( pid );
 149             if (!thread) thread = get_thread_from_pid( pid );
 150             handle_child_status( thread, pid, status, -1 );
 151         }
 152         else break;
 153     }
 154 }
 155
 156 /* return the Unix pid to use in ptrace calls for a given process */
 157 static int get_ptrace_pid( struct thread *thread )
 158 {
 159 #ifdef linux  /* linux always uses thread id */
 160     if (thread->unix_tid != -1) return thread->unix_tid;
 161 #endif
 162     return thread->unix_pid;
 163 }
 164
 165 /* return the Unix tid to use in ptrace calls for a given thread */
 166 static int get_ptrace_tid( struct thread *thread )
 167 {
 168     if (thread->unix_tid != -1) return thread->unix_tid;
 169     return thread->unix_pid;
 170 }
 171
 172 /* wait for a ptraced child to get a certain signal */
 173 static int waitpid_thread( struct thread *thread, int signal )
 174 {
 175     int res, status;
 176
 177     start_watchdog();
 178     for (;;)
 179     {
 180         if ((res = waitpid( get_ptrace_pid(thread), &status, WUNTRACED | __WALL )) == -1)
 181         {
 182             if (errno == EINTR)
 183             {
 184                 if (!watchdog_triggered()) continue;
 185                 if (debug_level) fprintf( stderr, "%04x: *watchdog* waitpid aborted\n", thread->id );
 186             }
 187             else if (errno == ECHILD)  /* must have died */
 188             {
 189                 thread->unix_pid = -1;
 190                 thread->unix_tid = -1;
 191             }
 192             else perror( "waitpid" );
 193             stop_watchdog();
 194             return 0;
 195         }
 196         res = handle_child_status( thread, res, status, signal );
 197         if (!res || res == signal) break;
 198     }
 199     stop_watchdog();
 200     return (thread->unix_pid != -1);
 201 }
 202
 203 /* send a signal to a specific thread */
 204 static inline int tkill( int tgid, int pid, int sig )
 205 {
 206 #ifdef __linux__
 207     int ret = syscall( __NR_tgkill, tgid, pid, sig );
 208     if (ret < 0 && errno == ENOSYS) ret = syscall( __NR_tkill, pid, sig );
 209     return ret;
 210 #elif (defined(__FreeBSD__) || defined (__FreeBSD_kernel__)) && defined(HAVE_THR_KILL2)
 211     return thr_kill2( tgid, pid, sig );
 212 #else
 213     errno = ENOSYS;
 214     return -1;
 215 #endif
 216 }
 217
 218 /* initialize the process tracing mechanism */
 219 void init_tracing_mechanism(void)
 220 {
 221     /* no initialization needed for ptrace */
 222 }
 223
 224 /* initialize the per-process tracing mechanism */
 225 void init_process_tracing( struct process *process )
 226 {
 227     /* ptrace setup is done on-demand */
 228 }
 229
 230 /* terminate the per-process tracing mechanism */
 231 void finish_process_tracing( struct process *process )
 232 {
 233 }
 234
 235 /* send a Unix signal to a specific thread */
 236 int send_thread_signal( struct thread *thread, int sig )
 237 {
 238     int ret = -1;
 239
 240     if (thread->unix_pid != -1)
 241     {
 242         if (thread->unix_tid != -1)
 243         {
 244             ret = tkill( thread->unix_pid, thread->unix_tid, sig );
 245             if (ret == -1 && errno == ENOSYS) ret = kill( thread->unix_pid, sig );
 246         }
 247         else ret = kill( thread->unix_pid, sig );
 248
 249         if (ret == -1 && errno == ESRCH) /* thread got killed */
 250         {
 251             thread->unix_pid = -1;
 252             thread->unix_tid = -1;
 253         }
 254     }
 255     if (debug_level && ret != -1)
 256         fprintf( stderr, "%04x: *sent signal* signal=%d\n", thread->id, sig );
 257     return (ret != -1);
 258 }
 259
 260 /* resume a thread after we have used ptrace on it */
 261 static void resume_after_ptrace( struct thread *thread )
 262 {
 263     if (thread->unix_pid == -1) return;
 264     if (ptrace( PTRACE_DETACH, get_ptrace_pid(thread), (caddr_t)1, 0 ) == -1)
 265     {
 266         if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1;  /* thread got killed */
 267     }
 268 }
 269
 270 /* suspend a thread to allow using ptrace on it */
 271 /* you must do a resume_after_ptrace when finished with the thread */
 272 static int suspend_for_ptrace( struct thread *thread )
 273 {
 274     /* can't stop a thread while initialisation is in progress */
 275     if (thread->unix_pid == -1 || !is_process_init_done(thread->process)) goto error;
 276
 277     /* this may fail if the client is already being debugged */
 278     if (ptrace( PTRACE_ATTACH, get_ptrace_pid(thread), 0, 0 ) == -1)
 279     {
 280         if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1;  /* thread got killed */
 281         goto error;
 282     }
 283     if (waitpid_thread( thread, SIGSTOP )) return 1;
 284     resume_after_ptrace( thread );
 285  error:
 286     set_error( STATUS_ACCESS_DENIED );
 287     return 0;
 288 }
 289
 290 /* read a long from a thread address space */
 291 static int read_thread_long( struct thread *thread, void *addr, unsigned long *data )
 292 {
 293     errno = 0;
 294     *data = ptrace( PTRACE_PEEKDATA, get_ptrace_pid(thread), (caddr_t)addr, 0 );
 295     if ( *data == -1 && errno)
 296     {
 297         file_set_error();
 298         return -1;
 299     }
 300     return 0;
 301 }
 302
 303 static int read_thread_int( struct thread *thread, void *addr, unsigned int *data )
 304 {
 305     unsigned long long_data;
 306     int ret;
 307
 308     ret = read_thread_long( thread, addr, &long_data );
 309     *data = long_data;
 310     return ret;
 311 }
 312
 313 /* write a long to a thread address space */
 314 static long write_thread_long( struct thread *thread, void *addr, unsigned long data, unsigned long mask )
 315 {
 316     unsigned long old_data;
 317     int res;
 318
 319     if (mask != ~0ul)
 320     {
 321         if (read_thread_long( thread, addr, &old_data ) == -1) return -1;
 322         data = (data & mask) | (old_data & ~mask);
 323     }
 324     if ((res = ptrace( PTRACE_POKEDATA, get_ptrace_pid(thread), (caddr_t)addr, data )) == -1)
 325         file_set_error();
 326     return res;
 327 }
 328
 329 /* return a thread of the process suitable for ptracing */
 330 static struct thread *get_ptrace_thread( struct process *process )
 331 {
 332     struct thread *thread;
 333
 334     LIST_FOR_EACH_ENTRY( thread, &process->thread_list, struct thread, proc_entry )
 335     {
 336         if (thread->unix_pid != -1) return thread;
 337     }
 338     set_error( STATUS_PROCESS_IS_TERMINATING );  /* process is dead */
 339     return NULL;
 340 }
 341
 342 /* read data from a process memory space */
 343 int read_process_memory( struct process *process, client_ptr_t ptr, data_size_t size, char *dest )
 344 {
 345     struct thread *thread = get_ptrace_thread( process );
 346     unsigned int first_offset, last_offset, len;
 347     unsigned long data, *addr;
 348
 349     if (!thread) return 0;
 350
 351     if ((unsigned long)ptr != ptr)
 352     {
 353         set_error( STATUS_ACCESS_DENIED );
 354         return 0;
 355     }
 356
 357     first_offset = ptr % sizeof(long);
 358     last_offset = (size + first_offset) % sizeof(long);
 359     if (!last_offset) last_offset = sizeof(long);
 360
 361     addr = (unsigned long *)(unsigned long)(ptr - first_offset);
 362     len = (size + first_offset + sizeof(long) - 1) / sizeof(long);
 363
 364     if (suspend_for_ptrace( thread ))
 365     {
 366         if (len > 3)  /* /proc/pid/mem should be faster for large sizes */
 367         {
 368             char procmem[24];
 369             int fd;
 370
 371             sprintf( procmem, "/proc/%u/mem", process->unix_pid );
 372             if ((fd = open( procmem, O_RDONLY )) != -1)
 373             {
 374                 ssize_t ret = pread( fd, dest, size, ptr );
 375                 close( fd );
 376                 if (ret == size)
 377                 {
 378                     len = 0;
 379                     goto done;
 380                 }
 381             }
 382         }
 383
 384         if (len > 1)
 385         {
 386             if (read_thread_long( thread, addr++, &data ) == -1) goto done;
 387             memcpy( dest, (char *)&data + first_offset, sizeof(long) - first_offset );
 388             dest += sizeof(long) - first_offset;
 389             first_offset = 0;
 390             len--;
 391         }
 392
 393         while (len > 1)
 394         {
 395             if (read_thread_long( thread, addr++, &data ) == -1) goto done;
 396             memcpy( dest, &data, sizeof(long) );
 397             dest += sizeof(long);
 398             len--;
 399         }
 400
 401         if (read_thread_long( thread, addr++, &data ) == -1) goto done;
 402         memcpy( dest, (char *)&data + first_offset, last_offset - first_offset );
 403         len--;
 404
 405     done:
 406         resume_after_ptrace( thread );
 407     }
 408     return !len;
 409 }
 410
 411 /* make sure we can write to the whole address range */
 412 /* len is the total size (in longs) */
 413 static int check_process_write_access( struct thread *thread, long *addr, data_size_t len )
 414 {
 415     int page = get_page_size() / sizeof(long);
 416
 417     for (;;)
 418     {
 419         if (write_thread_long( thread, addr, 0, 0 ) == -1) return 0;
 420         if (len <= page) break;
 421         addr += page;
 422         len -= page;
 423     }
 424     return (write_thread_long( thread, addr + len - 1, 0, 0 ) != -1);
 425 }
 426
 427 /* write data to a process memory space */
 428 int write_process_memory( struct process *process, client_ptr_t ptr, data_size_t size, const char *src )
 429 {
 430     struct thread *thread = get_ptrace_thread( process );
 431     int ret = 0;
 432     long data = 0;
 433     data_size_t len;
 434     long *addr;
 435     unsigned long first_mask, first_offset, last_mask, last_offset;
 436
 437     if (!thread) return 0;
 438
 439     if ((unsigned long)ptr != ptr)
 440     {
 441         set_error( STATUS_ACCESS_DENIED );
 442         return 0;
 443     }
 444
 445     /* compute the mask for the first long */
 446     first_mask = ~0;
 447     first_offset = ptr % sizeof(long);
 448     memset( &first_mask, 0, first_offset );
 449
 450     /* compute the mask for the last long */
 451     last_offset = (size + first_offset) % sizeof(long);
 452     if (!last_offset) last_offset = sizeof(long);
 453     last_mask = 0;
 454     memset( &last_mask, 0xff, last_offset );
 455
 456     addr = (long *)(unsigned long)(ptr - first_offset);
 457     len = (size + first_offset + sizeof(long) - 1) / sizeof(long);
 458
 459     if (suspend_for_ptrace( thread ))
 460     {
 461         if (!check_process_write_access( thread, addr, len ))
 462         {
 463             set_error( STATUS_ACCESS_DENIED );
 464             goto done;
 465         }
 466
 467         if (len > 3)
 468         {
 469             char procmem[24];
 470             int fd;
 471
 472             sprintf( procmem, "/proc/%u/mem", process->unix_pid );
 473             if ((fd = open( procmem, O_WRONLY )) != -1)
 474             {
 475                 ssize_t r = pwrite( fd, src, size, ptr );
 476                 close( fd );
 477                 if (r == size)
 478                 {
 479                     ret = 1;
 480                     goto done;
 481                 }
 482             }
 483         }
 484
 485         /* first word is special */
 486         if (len > 1)
 487         {
 488             memcpy( (char *)&data + first_offset, src, sizeof(long) - first_offset );
 489             src += sizeof(long) - first_offset;
 490             if (write_thread_long( thread, addr++, data, first_mask ) == -1) goto done;
 491             first_offset = 0;
 492             len--;
 493         }
 494         else last_mask &= first_mask;
 495
 496         while (len > 1)
 497         {
 498             memcpy( &data, src, sizeof(long) );
 499             src += sizeof(long);
 500             if (write_thread_long( thread, addr++, data, ~0ul ) == -1) goto done;
 501             len--;
 502         }
 503
 504         /* last word is special too */
 505         memcpy( (char *)&data + first_offset, src, last_offset - first_offset );
 506         if (write_thread_long( thread, addr, data, last_mask ) == -1) goto done;
 507         ret = 1;
 508
 509     done:
 510         resume_after_ptrace( thread );
 511     }
 512     return ret;
 513 }
 514
 515 /* retrieve an LDT selector entry */
 516 void get_selector_entry( struct thread *thread, int entry, unsigned int *base,
 517                          unsigned int *limit, unsigned char *flags )
 518 {
 519     if (!thread->process->ldt_copy)
 520     {
 521         set_error( STATUS_ACCESS_DENIED );
 522         return;
 523     }
 524     if (entry >= 8192)
 525     {
 526         set_error( STATUS_ACCESS_VIOLATION );
 527         return;
 528     }
 529     if (suspend_for_ptrace( thread ))
 530     {
 531         unsigned int flags_buf;
 532         unsigned long addr = (unsigned long)thread->process->ldt_copy + (entry * 4);
 533
 534         if (read_thread_int( thread, (void *)addr, base ) == -1) goto done;
 535         if (read_thread_int( thread, (void *)(addr + (8192 * 4)), limit ) == -1) goto done;
 536         addr = (unsigned long)thread->process->ldt_copy + (2 * 8192 * 4) + (entry & ~3);
 537         if (read_thread_int( thread, (void *)addr, &flags_buf ) == -1) goto done;
 538         *flags = flags_buf >> (entry & 3) * 8;
 539     done:
 540         resume_after_ptrace( thread );
 541     }
 542 }
 543
 544
 545 #if defined(linux) && (defined(HAVE_SYS_USER_H) || defined(HAVE_ASM_USER_H)) \
 546     && (defined(__i386__) || defined(__x86_64__))
 547
 548 #ifdef HAVE_SYS_USER_H
 549 #include <sys/user.h>
 550 #elif defined(HAVE_ASM_USER_H)
 551 #include <asm/user.h>
 552 #endif
 553
 554 /* debug register offset in struct user */
 555 #define DR_OFFSET(dr) ((((struct user *)0)->u_debugreg) + (dr))
 556
 557 /* initialize registers in new thread if necessary */
 558 void init_thread_context( struct thread *thread )
 559 {
 560     /* Linux doesn't clear all registers, but hopefully enough to avoid spurious breakpoints */
 561     thread->system_regs = 0;
 562 }
 563
 564 /* retrieve the thread x86 registers */
 565 void get_thread_context( struct thread *thread, context_t *context, unsigned int flags )
 566 {
 567     int i, pid = get_ptrace_tid(thread);
 568     long data[8];
 569
 570     /* all other regs are handled on the client side */
 571     assert( flags == SERVER_CTX_DEBUG_REGISTERS );
 572
 573     if (!(thread->system_regs & SERVER_CTX_DEBUG_REGISTERS))
 574     {
 575         /* caller has initialized everything to 0 already, just return */
 576         context->flags |= SERVER_CTX_DEBUG_REGISTERS;
 577         return;
 578     }
 579
 580     if (!suspend_for_ptrace( thread )) return;
 581
 582     for (i = 0; i < 8; i++)
 583     {
 584         if (i == 4 || i == 5) continue;
 585         errno = 0;
 586         data[i] = ptrace( PTRACE_PEEKUSER, pid, DR_OFFSET(i), 0 );
 587         if ((data[i] == -1) && errno)
 588         {
 589             file_set_error();
 590             goto done;
 591         }
 592     }
 593     switch (context->machine)
 594     {
 595     case IMAGE_FILE_MACHINE_I386:
 596         context->debug.i386_regs.dr0 = data[0];
 597         context->debug.i386_regs.dr1 = data[1];
 598         context->debug.i386_regs.dr2 = data[2];
 599         context->debug.i386_regs.dr3 = data[3];
 600         context->debug.i386_regs.dr6 = data[6];
 601         context->debug.i386_regs.dr7 = data[7];
 602         break;
 603     case IMAGE_FILE_MACHINE_AMD64:
 604         context->debug.x86_64_regs.dr0 = data[0];
 605         context->debug.x86_64_regs.dr1 = data[1];
 606         context->debug.x86_64_regs.dr2 = data[2];
 607         context->debug.x86_64_regs.dr3 = data[3];
 608         context->debug.x86_64_regs.dr6 = data[6];
 609         context->debug.x86_64_regs.dr7 = data[7];
 610         break;
 611     default:
 612         set_error( STATUS_INVALID_PARAMETER );
 613         goto done;
 614     }
 615     context->flags |= SERVER_CTX_DEBUG_REGISTERS;
 616 done:
 617     resume_after_ptrace( thread );
 618 }
 619
 620 /* set the thread x86 registers */
 621 void set_thread_context( struct thread *thread, const context_t *context, unsigned int flags )
 622 {
 623     int pid = get_ptrace_tid( thread );
 624
 625     /* all other regs are handled on the client side */
 626     assert( flags == SERVER_CTX_DEBUG_REGISTERS );
 627
 628     if (!suspend_for_ptrace( thread )) return;
 629
 630     switch (context->machine)
 631     {
 632     case IMAGE_FILE_MACHINE_I386:
 633         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), 0 ) == -1) goto error;
 634         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(0), context->debug.i386_regs.dr0 ) == -1) goto error;
 635         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(1), context->debug.i386_regs.dr1 ) == -1) goto error;
 636         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(2), context->debug.i386_regs.dr2 ) == -1) goto error;
 637         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(3), context->debug.i386_regs.dr3 ) == -1) goto error;
 638         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(6), context->debug.i386_regs.dr6 ) == -1) goto error;
 639         /* Linux 2.6.33+ needs enable bits set briefly to update value returned by PEEKUSER later */
 640         ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->debug.i386_regs.dr7 | 0x55 );
 641         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->debug.i386_regs.dr7 ) == -1) goto error;
 642         thread->system_regs |= SERVER_CTX_DEBUG_REGISTERS;
 643         break;
 644     case IMAGE_FILE_MACHINE_AMD64:
 645         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), 0 ) == -1) goto error;
 646         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(0), context->debug.x86_64_regs.dr0 ) == -1) goto error;
 647         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(1), context->debug.x86_64_regs.dr1 ) == -1) goto error;
 648         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(2), context->debug.x86_64_regs.dr2 ) == -1) goto error;
 649         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(3), context->debug.x86_64_regs.dr3 ) == -1) goto error;
 650         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(6), context->debug.x86_64_regs.dr6 ) == -1) goto error;
 651         ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->debug.x86_64_regs.dr7 | 0x55 );
 652         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->debug.x86_64_regs.dr7 ) == -1) goto error;
 653         thread->system_regs |= SERVER_CTX_DEBUG_REGISTERS;
 654         break;
 655     default:
 656         set_error( STATUS_INVALID_PARAMETER );
 657     }
 658     resume_after_ptrace( thread );
 659     return;
 660  error:
 661     file_set_error();
 662     resume_after_ptrace( thread );
 663 }
 664
 665 #elif defined(__i386__) && defined(PTRACE_GETDBREGS) && defined(PTRACE_SETDBREGS) && \
 666     (defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__OpenBSD__) || defined(__NetBSD__) || defined(__DragonFly__))
 667
 668 #include <machine/reg.h>
 669
 670 /* initialize registers in new thread if necessary */
 671 void init_thread_context( struct thread *thread )
 672 {
 673     if (!(thread->system_regs & SERVER_CTX_DEBUG_REGISTERS)) return;
 674
 675     /* FreeBSD doesn't clear the debug registers in new threads */
 676     if (suspend_for_ptrace( thread ))
 677     {
 678         struct dbreg dbregs;
 679
 680         memset( &dbregs, 0, sizeof(dbregs) );
 681         ptrace( PTRACE_SETDBREGS, get_ptrace_tid( thread ), (caddr_t)&dbregs, 0 );
 682         resume_after_ptrace( thread );
 683     }
 684     thread->system_regs = 0;
 685 }
 686
 687 /* retrieve the thread x86 registers */
 688 void get_thread_context( struct thread *thread, context_t *context, unsigned int flags )
 689 {
 690     int pid = get_ptrace_tid(thread);
 691     struct dbreg dbregs;
 692
 693     /* all other regs are handled on the client side */
 694     assert( flags == SERVER_CTX_DEBUG_REGISTERS );
 695
 696     if (!suspend_for_ptrace( thread )) return;
 697
 698     if (ptrace( PTRACE_GETDBREGS, pid, (caddr_t) &dbregs, 0 ) == -1) file_set_error();
 699     else
 700     {
 701 #ifdef DBREG_DRX
 702         /* needed for FreeBSD, the structure fields have changed under 5.x */
 703         context->debug.i386_regs.dr0 = DBREG_DRX((&dbregs), 0);
 704         context->debug.i386_regs.dr1 = DBREG_DRX((&dbregs), 1);
 705         context->debug.i386_regs.dr2 = DBREG_DRX((&dbregs), 2);
 706         context->debug.i386_regs.dr3 = DBREG_DRX((&dbregs), 3);
 707         context->debug.i386_regs.dr6 = DBREG_DRX((&dbregs), 6);
 708         context->debug.i386_regs.dr7 = DBREG_DRX((&dbregs), 7);
 709 #elif defined(__NetBSD__)
 710         context->debug.i386_regs.dr0 = dbregs.dr[0];
 711         context->debug.i386_regs.dr1 = dbregs.dr[1];
 712         context->debug.i386_regs.dr2 = dbregs.dr[2];
 713         context->debug.i386_regs.dr3 = dbregs.dr[3];
 714         context->debug.i386_regs.dr6 = dbregs.dr[6];
 715         context->debug.i386_regs.dr7 = dbregs.dr[7];
 716 #else
 717         context->debug.i386_regs.dr0 = dbregs.dr0;
 718         context->debug.i386_regs.dr1 = dbregs.dr1;
 719         context->debug.i386_regs.dr2 = dbregs.dr2;
 720         context->debug.i386_regs.dr3 = dbregs.dr3;
 721         context->debug.i386_regs.dr6 = dbregs.dr6;
 722         context->debug.i386_regs.dr7 = dbregs.dr7;
 723 #endif
 724         context->flags |= SERVER_CTX_DEBUG_REGISTERS;
 725     }
 726     resume_after_ptrace( thread );
 727 }
 728
 729 /* set the thread x86 registers */
 730 void set_thread_context( struct thread *thread, const context_t *context, unsigned int flags )
 731 {
 732     int pid = get_ptrace_tid(thread);
 733     struct dbreg dbregs;
 734
 735     /* all other regs are handled on the client side */
 736     assert( flags == SERVER_CTX_DEBUG_REGISTERS );
 737
 738     if (!suspend_for_ptrace( thread )) return;
 739
 740 #ifdef DBREG_DRX
 741     /* needed for FreeBSD, the structure fields have changed under 5.x */
 742     DBREG_DRX((&dbregs), 0) = context->debug.i386_regs.dr0;
 743     DBREG_DRX((&dbregs), 1) = context->debug.i386_regs.dr1;
 744     DBREG_DRX((&dbregs), 2) = context->debug.i386_regs.dr2;
 745     DBREG_DRX((&dbregs), 3) = context->debug.i386_regs.dr3;
 746     DBREG_DRX((&dbregs), 4) = 0;
 747     DBREG_DRX((&dbregs), 5) = 0;
 748     DBREG_DRX((&dbregs), 6) = context->debug.i386_regs.dr6;
 749     DBREG_DRX((&dbregs), 7) = context->debug.i386_regs.dr7;
 750 #elif defined(__NetBSD__)
 751     dbregs.dr[0] = context->debug.i386_regs.dr0;
 752     dbregs.dr[1] = context->debug.i386_regs.dr1;
 753     dbregs.dr[2] = context->debug.i386_regs.dr2;
 754     dbregs.dr[3] = context->debug.i386_regs.dr3;
 755     dbregs.dr[4] = 0;
 756     dbregs.dr[5] = 0;
 757     dbregs.dr[6] = context->debug.i386_regs.dr6;
 758     dbregs.dr[7] = context->debug.i386_regs.dr7;
 759 #else
 760     dbregs.dr0 = context->debug.i386_regs.dr0;
 761     dbregs.dr1 = context->debug.i386_regs.dr1;
 762     dbregs.dr2 = context->debug.i386_regs.dr2;
 763     dbregs.dr3 = context->debug.i386_regs.dr3;
 764     dbregs.dr4 = 0;
 765     dbregs.dr5 = 0;
 766     dbregs.dr6 = context->debug.i386_regs.dr6;
 767     dbregs.dr7 = context->debug.i386_regs.dr7;
 768 #endif
 769     if (ptrace( PTRACE_SETDBREGS, pid, (caddr_t)&dbregs, 0 ) != -1)
 770     {
 771         thread->system_regs |= SERVER_CTX_DEBUG_REGISTERS;
 772     }
 773     else file_set_error();
 774
 775     resume_after_ptrace( thread );
 776 }
 777
 778 #else  /* linux || __FreeBSD__ */
 779
 780 /* initialize registers in new thread if necessary */
 781 void init_thread_context( struct thread *thread )
 782 {
 783 }
 784
 785 /* retrieve the thread x86 registers */
 786 void get_thread_context( struct thread *thread, context_t *context, unsigned int flags )
 787 {
 788 }
 789
 790 /* set the thread x86 debug registers */
 791 void set_thread_context( struct thread *thread, const context_t *context, unsigned int flags )
 792 {
 793 }
 794
 795 #endif  /* linux || __FreeBSD__ */
 796
 797 #endif  /* USE_PTRACE */