server/ptrace.c

   1 /*
   2  * Server-side ptrace support
   3  *
   4  * Copyright (C) 1999 Alexandre Julliard
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  19  */
  20
  21 #include "config.h"
  22
  23 #include <assert.h>
  24 #include <errno.h>
  25 #include <stdio.h>
  26 #include <signal.h>
  27 #include <stdarg.h>
  28 #include <sys/types.h>
  29 #ifdef HAVE_SYS_PTRACE_H
  30 # include <sys/ptrace.h>
  31 #endif
  32 #ifdef HAVE_SYS_PARAM_H
  33 # include <sys/param.h>
  34 #endif
  35 #ifdef HAVE_SYS_WAIT_H
  36 # include <sys/wait.h>
  37 #endif
  38 #include <unistd.h>
  39
  40 #include "ntstatus.h"
  41 #define WIN32_NO_STATUS
  42 #include "winternl.h"
  43
  44 #include "file.h"
  45 #include "process.h"
  46 #include "thread.h"
  47
  48 #ifndef PTRACE_CONT
  49 #define PTRACE_CONT PT_CONTINUE
  50 #endif
  51 #ifndef PTRACE_SINGLESTEP
  52 #define PTRACE_SINGLESTEP PT_STEP
  53 #endif
  54 #ifndef PTRACE_ATTACH
  55 #define PTRACE_ATTACH PT_ATTACH
  56 #endif
  57 #ifndef PTRACE_DETACH
  58 #define PTRACE_DETACH PT_DETACH
  59 #endif
  60 #ifndef PTRACE_PEEKDATA
  61 #define PTRACE_PEEKDATA PT_READ_D
  62 #endif
  63 #ifndef PTRACE_POKEDATA
  64 #define PTRACE_POKEDATA PT_WRITE_D
  65 #endif
  66 #ifndef PTRACE_PEEKUSER
  67 #define PTRACE_PEEKUSER PT_READ_U
  68 #endif
  69 #ifndef PTRACE_POKEUSER
  70 #define PTRACE_POKEUSER PT_WRITE_U
  71 #endif
  72
  73 #ifdef PT_GETDBREGS
  74 #define PTRACE_GETDBREGS PT_GETDBREGS
  75 #endif
  76 #ifdef PT_SETDBREGS
  77 #define PTRACE_SETDBREGS PT_SETDBREGS
  78 #endif
  79
  80 #ifndef HAVE_SYS_PTRACE_H
  81 #define PT_CONTINUE 0
  82 #define PT_ATTACH   1
  83 #define PT_DETACH   2
  84 #define PT_READ_D   3
  85 #define PT_WRITE_D  4
  86 #define PT_STEP     5
  87 inline static int ptrace(int req, ...) { errno = EPERM; return -1; /*FAIL*/ }
  88 #endif  /* HAVE_SYS_PTRACE_H */
  89
  90 /* handle a status returned by wait4 */
  91 static int handle_child_status( struct thread *thread, int pid, int status, int want_sig )
  92 {
  93     if (WIFSTOPPED(status))
  94     {
  95         int sig = WSTOPSIG(status);
  96         if (debug_level && thread)
  97             fprintf( stderr, "%04x: *signal* signal=%d\n", thread->id, sig );
  98         if (sig != want_sig)
  99         {
 100             /* ignore other signals for now */
 101             ptrace( PTRACE_CONT, pid, (caddr_t)1, sig );
 102         }
 103         return sig;
 104     }
 105     if (thread && (WIFSIGNALED(status) || WIFEXITED(status)))
 106     {
 107         thread->unix_pid = -1;
 108         thread->unix_tid = -1;
 109         if (debug_level)
 110         {
 111             if (WIFSIGNALED(status))
 112                 fprintf( stderr, "%04x: *exited* signal=%d\n",
 113                          thread->id, WTERMSIG(status) );
 114             else
 115                 fprintf( stderr, "%04x: *exited* status=%d\n",
 116                          thread->id, WEXITSTATUS(status) );
 117         }
 118     }
 119     return 0;
 120 }
 121
 122 /* wait4 wrapper to handle missing __WALL flag in older kernels */
 123 static inline pid_t wait4_wrapper( pid_t pid, int *status, int options, struct rusage *usage )
 124 {
 125 #ifdef __WALL
 126     static int wall_flag = __WALL;
 127
 128     for (;;)
 129     {
 130         pid_t ret = wait4( pid, status, options | wall_flag, usage );
 131         if (ret != -1 || !wall_flag || errno != EINVAL) return ret;
 132         wall_flag = 0;
 133     }
 134 #else
 135     return wait4( pid, status, options, usage );
 136 #endif
 137 }
 138
 139 /* handle a SIGCHLD signal */
 140 void sigchld_callback(void)
 141 {
 142     int pid, status;
 143
 144     for (;;)
 145     {
 146         if (!(pid = wait4_wrapper( -1, &status, WUNTRACED | WNOHANG, NULL ))) break;
 147         if (pid != -1) handle_child_status( get_thread_from_pid(pid), pid, status, -1 );
 148         else break;
 149     }
 150 }
 151
 152 /* return the Unix pid to use in ptrace calls for a given thread */
 153 static int get_ptrace_pid( struct thread *thread )
 154 {
 155     if (thread->unix_tid != -1) return thread->unix_tid;
 156     return thread->unix_pid;
 157 }
 158
 159 /* wait for a ptraced child to get a certain signal */
 160 static int wait4_thread( struct thread *thread, int signal )
 161 {
 162     int res, status;
 163
 164     start_watchdog();
 165     for (;;)
 166     {
 167         if ((res = wait4_wrapper( get_ptrace_pid(thread), &status, WUNTRACED, NULL )) == -1)
 168         {
 169             if (errno == EINTR)
 170             {
 171                 if (!watchdog_triggered()) continue;
 172                 if (debug_level) fprintf( stderr, "%04x: *watchdog* wait4 aborted\n", thread->id );
 173             }
 174             else if (errno == ECHILD)  /* must have died */
 175             {
 176                 thread->unix_pid = -1;
 177                 thread->unix_tid = -1;
 178             }
 179             else perror( "wait4" );
 180             stop_watchdog();
 181             return 0;
 182         }
 183         res = handle_child_status( thread, res, status, signal );
 184         if (!res || res == signal) break;
 185     }
 186     stop_watchdog();
 187     return (thread->unix_pid != -1);
 188 }
 189
 190 /* send a signal to a specific thread */
 191 static inline int tkill( int tgid, int pid, int sig )
 192 {
 193     int ret = -ENOSYS;
 194
 195 #ifdef __linux__
 196 # ifdef __i386__
 197     __asm__( "pushl %%ebx\n\t"
 198              "movl %2,%%ebx\n\t"
 199              "int $0x80\n\t"
 200              "popl %%ebx\n\t"
 201              : "=a" (ret)
 202              : "0" (270) /*SYS_tgkill*/, "r" (tgid), "c" (pid), "d" (sig) );
 203     if (ret == -ENOSYS)
 204         __asm__( "pushl %%ebx\n\t"
 205                  "movl %2,%%ebx\n\t"
 206                  "int $0x80\n\t"
 207                  "popl %%ebx\n\t"
 208                  : "=a" (ret)
 209                  : "0" (238) /*SYS_tkill*/, "r" (pid), "c" (sig) );
 210 # elif defined(__x86_64__)
 211     __asm__( "syscall" : "=a" (ret)
 212              : "0" (200) /*SYS_tkill*/, "D" (pid), "S" (sig) );
 213 # endif
 214 #endif  /* __linux__ */
 215
 216     if (ret >= 0) return ret;
 217     errno = -ret;
 218     return -1;
 219 }
 220
 221 /* send a Unix signal to a specific thread */
 222 int send_thread_signal( struct thread *thread, int sig )
 223 {
 224     int ret = -1;
 225
 226     if (thread->unix_pid != -1)
 227     {
 228         if (thread->unix_tid != -1)
 229         {
 230             ret = tkill( thread->unix_pid, thread->unix_tid, sig );
 231             if (ret == -1 && errno == ENOSYS) ret = kill( thread->unix_pid, sig );
 232         }
 233         else ret = kill( thread->unix_pid, sig );
 234
 235         if (ret == -1 && errno == ESRCH) /* thread got killed */
 236         {
 237             thread->unix_pid = -1;
 238             thread->unix_tid = -1;
 239         }
 240     }
 241     return (ret != -1);
 242 }
 243
 244 /* resume a thread after we have used ptrace on it */
 245 static void resume_after_ptrace( struct thread *thread )
 246 {
 247     if (thread->unix_pid == -1) return;
 248     if (ptrace( PTRACE_DETACH, get_ptrace_pid(thread), (caddr_t)1, 0 ) == -1)
 249     {
 250         if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1;  /* thread got killed */
 251     }
 252 }
 253
 254 /* suspend a thread to allow using ptrace on it */
 255 /* you must do a resume_after_ptrace when finished with the thread */
 256 static int suspend_for_ptrace( struct thread *thread )
 257 {
 258     /* can't stop a thread while initialisation is in progress */
 259     if (thread->unix_pid == -1 || !is_process_init_done(thread->process)) goto error;
 260
 261     /* this may fail if the client is already being debugged */
 262     if (ptrace( PTRACE_ATTACH, get_ptrace_pid(thread), 0, 0 ) == -1)
 263     {
 264         if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1;  /* thread got killed */
 265         goto error;
 266     }
 267     if (wait4_thread( thread, SIGSTOP )) return 1;
 268     resume_after_ptrace( thread );
 269  error:
 270     set_error( STATUS_ACCESS_DENIED );
 271     return 0;
 272 }
 273
 274 /* read an int from a thread address space */
 275 static int read_thread_int( struct thread *thread, int *addr, int *data )
 276 {
 277     errno = 0;
 278     *data = ptrace( PTRACE_PEEKDATA, get_ptrace_pid(thread), (caddr_t)addr, 0 );
 279     if ( *data == -1 && errno)
 280     {
 281         file_set_error();
 282         return -1;
 283     }
 284     return 0;
 285 }
 286
 287 /* write an int to a thread address space */
 288 static int write_thread_int( struct thread *thread, int *addr, int data, unsigned int mask )
 289 {
 290     int res;
 291     if (mask != ~0u)
 292     {
 293         if (read_thread_int( thread, addr, &res ) == -1) return -1;
 294         data = (data & mask) | (res & ~mask);
 295     }
 296     if ((res = ptrace( PTRACE_POKEDATA, get_ptrace_pid(thread), (caddr_t)addr, data )) == -1)
 297         file_set_error();
 298     return res;
 299 }
 300
 301 /* return a thread of the process suitable for ptracing */
 302 static struct thread *get_ptrace_thread( struct process *process )
 303 {
 304     struct thread *thread;
 305
 306     LIST_FOR_EACH_ENTRY( thread, &process->thread_list, struct thread, proc_entry )
 307     {
 308         if (thread->unix_pid != -1) return thread;
 309     }
 310     set_error( STATUS_ACCESS_DENIED );  /* process is dead */
 311     return NULL;
 312 }
 313
 314 /* read data from a process memory space */
 315 int read_process_memory( struct process *process, const void *ptr, data_size_t size, char *dest )
 316 {
 317     struct thread *thread = get_ptrace_thread( process );
 318     unsigned int first_offset, last_offset, len;
 319     int data, *addr;
 320
 321     if (!thread) return 0;
 322
 323     first_offset = (unsigned long)ptr % sizeof(int);
 324     last_offset = (size + first_offset) % sizeof(int);
 325     if (!last_offset) last_offset = sizeof(int);
 326
 327     addr = (int *)((char *)ptr - first_offset);
 328     len = (size + first_offset + sizeof(int) - 1) / sizeof(int);
 329
 330     if (suspend_for_ptrace( thread ))
 331     {
 332         if (len > 1)
 333         {
 334             if (read_thread_int( thread, addr++, &data ) == -1) goto done;
 335             memcpy( dest, (char *)&data + first_offset, sizeof(int) - first_offset );
 336             dest += sizeof(int) - first_offset;
 337             first_offset = 0;
 338             len--;
 339         }
 340
 341         while (len > 1)
 342         {
 343             if (read_thread_int( thread, addr++, &data ) == -1) goto done;
 344             memcpy( dest, &data, sizeof(int) );
 345             dest += sizeof(int);
 346             len--;
 347         }
 348
 349         if (read_thread_int( thread, addr++, &data ) == -1) goto done;
 350         memcpy( dest, (char *)&data + first_offset, last_offset - first_offset );
 351         len--;
 352
 353     done:
 354         resume_after_ptrace( thread );
 355     }
 356     return !len;
 357 }
 358
 359 /* make sure we can write to the whole address range */
 360 /* len is the total size (in ints) */
 361 static int check_process_write_access( struct thread *thread, int *addr, data_size_t len )
 362 {
 363     int page = get_page_size() / sizeof(int);
 364
 365     for (;;)
 366     {
 367         if (write_thread_int( thread, addr, 0, 0 ) == -1) return 0;
 368         if (len <= page) break;
 369         addr += page;
 370         len -= page;
 371     }
 372     return (write_thread_int( thread, addr + len - 1, 0, 0 ) != -1);
 373 }
 374
 375 /* write data to a process memory space */
 376 int write_process_memory( struct process *process, void *ptr, data_size_t size, const char *src )
 377 {
 378     struct thread *thread = get_ptrace_thread( process );
 379     int ret = 0, data = 0;
 380     data_size_t len;
 381     int *addr;
 382     unsigned int first_mask, first_offset, last_mask, last_offset;
 383
 384     if (!thread) return 0;
 385
 386     /* compute the mask for the first int */
 387     first_mask = ~0;
 388     first_offset = (unsigned long)ptr % sizeof(int);
 389     memset( &first_mask, 0, first_offset );
 390
 391     /* compute the mask for the last int */
 392     last_offset = (size + first_offset) % sizeof(int);
 393     if (!last_offset) last_offset = sizeof(int);
 394     last_mask = 0;
 395     memset( &last_mask, 0xff, last_offset );
 396
 397     addr = (int *)((char *)ptr - first_offset);
 398     len = (size + first_offset + sizeof(int) - 1) / sizeof(int);
 399
 400     if (suspend_for_ptrace( thread ))
 401     {
 402         if (!check_process_write_access( thread, addr, len ))
 403         {
 404             set_error( STATUS_ACCESS_DENIED );
 405             goto done;
 406         }
 407         /* first word is special */
 408         if (len > 1)
 409         {
 410             memcpy( (char *)&data + first_offset, src, sizeof(int) - first_offset );
 411             src += sizeof(int) - first_offset;
 412             if (write_thread_int( thread, addr++, data, first_mask ) == -1) goto done;
 413             first_offset = 0;
 414             len--;
 415         }
 416         else last_mask &= first_mask;
 417
 418         while (len > 1)
 419         {
 420             memcpy( &data, src, sizeof(int) );
 421             src += sizeof(int);
 422             if (write_thread_int( thread, addr++, data, ~0 ) == -1) goto done;
 423             len--;
 424         }
 425
 426         /* last word is special too */
 427         memcpy( (char *)&data + first_offset, src, last_offset - first_offset );
 428         if (write_thread_int( thread, addr, data, last_mask ) == -1) goto done;
 429         ret = 1;
 430
 431     done:
 432         resume_after_ptrace( thread );
 433     }
 434     return ret;
 435 }
 436
 437 /* retrieve an LDT selector entry */
 438 void get_selector_entry( struct thread *thread, int entry, unsigned int *base,
 439                          unsigned int *limit, unsigned char *flags )
 440 {
 441     if (!thread->process->ldt_copy)
 442     {
 443         set_error( STATUS_ACCESS_DENIED );
 444         return;
 445     }
 446     if (entry >= 8192)
 447     {
 448         set_error( STATUS_INVALID_PARAMETER );  /* FIXME */
 449         return;
 450     }
 451     if (suspend_for_ptrace( thread ))
 452     {
 453         unsigned char flags_buf[4];
 454         int *addr = (int *)thread->process->ldt_copy + entry;
 455         if (read_thread_int( thread, addr, (int *)base ) == -1) goto done;
 456         if (read_thread_int( thread, addr + 8192, (int *)limit ) == -1) goto done;
 457         addr = (int *)thread->process->ldt_copy + 2*8192 + (entry >> 2);
 458         if (read_thread_int( thread, addr, (int *)flags_buf ) == -1) goto done;
 459         *flags = flags_buf[entry & 3];
 460     done:
 461         resume_after_ptrace( thread );
 462     }
 463 }
 464
 465
 466 #if defined(linux) && (defined(__i386__) || defined(__x86_64__))
 467
 468 #ifdef HAVE_SYS_USER_H
 469 # include <sys/user.h>
 470 #endif
 471
 472 /* debug register offset in struct user */
 473 #define DR_OFFSET(dr) ((((struct user *)0)->u_debugreg) + (dr))
 474
 475 /* retrieve the thread x86 registers */
 476 void get_thread_context( struct thread *thread, CONTEXT *context, unsigned int flags )
 477 {
 478     int i, pid = get_ptrace_pid(thread);
 479     long data[8];
 480
 481     /* all other regs are handled on the client side */
 482     assert( (flags | CONTEXT_i386) == CONTEXT_DEBUG_REGISTERS );
 483
 484     if (!suspend_for_ptrace( thread )) return;
 485
 486     for (i = 0; i < 8; i++)
 487     {
 488         if (i == 4 || i == 5) continue;
 489         errno = 0;
 490         data[i] = ptrace( PTRACE_PEEKUSER, pid, DR_OFFSET(i), 0 );
 491         if ((data[i] == -1) && errno)
 492         {
 493             file_set_error();
 494             goto done;
 495         }
 496     }
 497     context->Dr0 = data[0];
 498     context->Dr1 = data[1];
 499     context->Dr2 = data[2];
 500     context->Dr3 = data[3];
 501     context->Dr6 = data[6];
 502     context->Dr7 = data[7];
 503     context->ContextFlags |= CONTEXT_DEBUG_REGISTERS;
 504 done:
 505     resume_after_ptrace( thread );
 506 }
 507
 508 /* set the thread x86 registers */
 509 void set_thread_context( struct thread *thread, const CONTEXT *context, unsigned int flags )
 510 {
 511     int pid = get_ptrace_pid( thread );
 512
 513     /* all other regs are handled on the client side */
 514     assert( (flags | CONTEXT_i386) == CONTEXT_DEBUG_REGISTERS );
 515
 516     if (!suspend_for_ptrace( thread )) return;
 517
 518     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(0), context->Dr0 ) == -1) goto error;
 519     if (thread->context) thread->context->Dr0 = context->Dr0;
 520     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(1), context->Dr1 ) == -1) goto error;
 521     if (thread->context) thread->context->Dr1 = context->Dr1;
 522     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(2), context->Dr2 ) == -1) goto error;
 523     if (thread->context) thread->context->Dr2 = context->Dr2;
 524     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(3), context->Dr3 ) == -1) goto error;
 525     if (thread->context) thread->context->Dr3 = context->Dr3;
 526     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(6), context->Dr6 ) == -1) goto error;
 527     if (thread->context) thread->context->Dr6 = context->Dr6;
 528     if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->Dr7 ) == -1) goto error;
 529     if (thread->context) thread->context->Dr7 = context->Dr7;
 530     resume_after_ptrace( thread );
 531     return;
 532  error:
 533     file_set_error();
 534     resume_after_ptrace( thread );
 535 }
 536
 537 #elif defined(__i386__) && defined(PTRACE_GETDBREGS) && defined(PTRACE_SETDBREGS) && \
 538     (defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__OpenBSD__) || defined(__NetBSD__))
 539
 540 #include <machine/reg.h>
 541
 542 /* retrieve the thread x86 registers */
 543 void get_thread_context( struct thread *thread, CONTEXT *context, unsigned int flags )
 544 {
 545     int pid = get_ptrace_pid(thread);
 546     struct dbreg dbregs;
 547
 548     /* all other regs are handled on the client side */
 549     assert( (flags | CONTEXT_i386) == CONTEXT_DEBUG_REGISTERS );
 550
 551     if (!suspend_for_ptrace( thread )) return;
 552
 553     if (ptrace( PTRACE_GETDBREGS, pid, (caddr_t) &dbregs, 0 ) == -1) file_set_error();
 554     else
 555     {
 556 #ifdef DBREG_DRX
 557         /* needed for FreeBSD, the structure fields have changed under 5.x */
 558         context->Dr0 = DBREG_DRX((&dbregs), 0);
 559         context->Dr1 = DBREG_DRX((&dbregs), 1);
 560         context->Dr2 = DBREG_DRX((&dbregs), 2);
 561         context->Dr3 = DBREG_DRX((&dbregs), 3);
 562         context->Dr6 = DBREG_DRX((&dbregs), 6);
 563         context->Dr7 = DBREG_DRX((&dbregs), 7);
 564 #else
 565         context->Dr0 = dbregs.dr0;
 566         context->Dr1 = dbregs.dr1;
 567         context->Dr2 = dbregs.dr2;
 568         context->Dr3 = dbregs.dr3;
 569         context->Dr6 = dbregs.dr6;
 570         context->Dr7 = dbregs.dr7;
 571 #endif
 572         context->ContextFlags |= CONTEXT_DEBUG_REGISTERS;
 573     }
 574     resume_after_ptrace( thread );
 575 }
 576
 577 /* set the thread x86 registers */
 578 void set_thread_context( struct thread *thread, const CONTEXT *context, unsigned int flags )
 579 {
 580     int pid = get_ptrace_pid(thread);
 581     struct dbreg dbregs;
 582
 583     /* all other regs are handled on the client side */
 584     assert( (flags | CONTEXT_i386) == CONTEXT_DEBUG_REGISTERS );
 585
 586     if (!suspend_for_ptrace( thread )) return;
 587
 588 #ifdef DBREG_DRX
 589     /* needed for FreeBSD, the structure fields have changed under 5.x */
 590     DBREG_DRX((&dbregs), 0) = context->Dr0;
 591     DBREG_DRX((&dbregs), 1) = context->Dr1;
 592     DBREG_DRX((&dbregs), 2) = context->Dr2;
 593     DBREG_DRX((&dbregs), 3) = context->Dr3;
 594     DBREG_DRX((&dbregs), 4) = 0;
 595     DBREG_DRX((&dbregs), 5) = 0;
 596     DBREG_DRX((&dbregs), 6) = context->Dr6;
 597     DBREG_DRX((&dbregs), 7) = context->Dr7;
 598 #else
 599     dbregs.dr0 = context->Dr0;
 600     dbregs.dr1 = context->Dr1;
 601     dbregs.dr2 = context->Dr2;
 602     dbregs.dr3 = context->Dr3;
 603     dbregs.dr4 = 0;
 604     dbregs.dr5 = 0;
 605     dbregs.dr6 = context->Dr6;
 606     dbregs.dr7 = context->Dr7;
 607 #endif
 608     if (ptrace( PTRACE_SETDBREGS, pid, (caddr_t) &dbregs, 0 ) == -1) file_set_error();
 609     else if (thread->context)  /* update the cached values */
 610     {
 611         thread->context->Dr0 = context->Dr0;
 612         thread->context->Dr1 = context->Dr1;
 613         thread->context->Dr2 = context->Dr2;
 614         thread->context->Dr3 = context->Dr3;
 615         thread->context->Dr6 = context->Dr6;
 616         thread->context->Dr7 = context->Dr7;
 617     }
 618     resume_after_ptrace( thread );
 619 }
 620
 621 #else  /* linux || __FreeBSD__ */
 622
 623 /* retrieve the thread x86 registers */
 624 void get_thread_context( struct thread *thread, CONTEXT *context, unsigned int flags )
 625 {
 626 }
 627
 628 /* set the thread x86 debug registers */
 629 void set_thread_context( struct thread *thread, const CONTEXT *context, unsigned int flags )
 630 {
 631 }
 632
 633 #endif  /* linux || __FreeBSD__ */