server/context_i386.c

   1 /*
   2  * i386 register context 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include "config.h"
  22
  23 #ifdef __i386__
  24
  25 #include <assert.h>
  26 #include <errno.h>
  27 #ifdef HAVE_SYS_REG_H
  28 #include <sys/reg.h>
  29 #endif
  30 #include <unistd.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
  38 #include "winbase.h"
  39
  40 #include "file.h"
  41 #include "thread.h"
  42 #include "request.h"
  43
  44 #ifndef PTRACE_PEEKUSER
  45 #  ifdef PTRACE_PEEKUSR /* libc5 uses USR not USER */
  46 #    define PTRACE_PEEKUSER PTRACE_PEEKUSR
  47 #  else
  48 #    define PTRACE_PEEKUSER PT_READ_U
  49 #  endif
  50 #endif
  51
  52 #ifndef PTRACE_POKEUSER
  53 #  ifdef PTRACE_POKEUSR /* libc5 uses USR not USER */
  54 #    define PTRACE_POKEUSER PTRACE_POKEUSR
  55 #  else
  56 #    define PTRACE_POKEUSER PT_WRITE_U
  57 #  endif
  58 #endif
  59
  60 #ifndef PTRACE_GETREGS
  61 #define PTRACE_GETREGS PT_GETREGS
  62 #endif
  63 #ifndef PTRACE_GETFPREGS
  64 #define PTRACE_GETFPREGS PT_GETFPREGS
  65 #endif
  66 #ifndef PTRACE_SETREGS
  67 #define PTRACE_SETREGS PT_SETREGS
  68 #endif
  69 #ifndef PTRACE_SETFPREGS
  70 #define PTRACE_SETFPREGS PT_SETFPREGS
  71 #endif
  72
  73 #ifdef PT_GETDBREGS
  74 #define PTRACE_GETDBREGS PT_GETDBREGS
  75 #endif
  76
  77 #ifdef PT_SETDBREGS
  78 #define PTRACE_SETDBREGS PT_SETDBREGS
  79 #endif
  80
  81 #ifdef linux
  82 #ifdef HAVE_SYS_USER_H
  83 # include <sys/user.h>
  84 #endif
  85
  86 /* user_regs definitions from asm/user.h */
  87 struct kernel_user_regs_struct
  88 {
  89     long ebx, ecx, edx, esi, edi, ebp, eax;
  90     unsigned short ds, __ds, es, __es;
  91     unsigned short fs, __fs, gs, __gs;
  92     long orig_eax, eip;
  93     unsigned short cs, __cs;
  94     long eflags, esp;
  95     unsigned short ss, __ss;
  96 };
  97
  98 /* debug register offset in struct user */
  99 #define DR_OFFSET(dr) ((int)((((struct user *)0)->u_debugreg) + (dr)))
 100
 101 /* retrieve a debug register */
 102 static inline int get_debug_reg( int pid, int num, DWORD *data )
 103 {
 104     int res;
 105     errno = 0;
 106     res = ptrace( PTRACE_PEEKUSER, pid, DR_OFFSET(num), 0 );
 107     if ((res == -1) && errno)
 108     {
 109         file_set_error();
 110         return -1;
 111     }
 112     *data = res;
 113     return 0;
 114 }
 115
 116 /* retrieve a thread context */
 117 static void get_thread_context( struct thread *thread, unsigned int flags, CONTEXT *context )
 118 {
 119     int pid = get_ptrace_pid(thread);
 120     if (flags & CONTEXT_FULL)
 121     {
 122         struct kernel_user_regs_struct regs;
 123         if (ptrace( PTRACE_GETREGS, pid, 0, &regs ) == -1) goto error;
 124         if (flags & CONTEXT_INTEGER)
 125         {
 126             context->Eax = regs.eax;
 127             context->Ebx = regs.ebx;
 128             context->Ecx = regs.ecx;
 129             context->Edx = regs.edx;
 130             context->Esi = regs.esi;
 131             context->Edi = regs.edi;
 132         }
 133         if (flags & CONTEXT_CONTROL)
 134         {
 135             context->Ebp    = regs.ebp;
 136             context->Esp    = regs.esp;
 137             context->Eip    = regs.eip;
 138             context->SegCs  = regs.cs;
 139             context->SegSs  = regs.ss;
 140             context->EFlags = regs.eflags;
 141         }
 142         if (flags & CONTEXT_SEGMENTS)
 143         {
 144             context->SegDs = regs.ds;
 145             context->SegEs = regs.es;
 146             context->SegFs = regs.fs;
 147             context->SegGs = regs.gs;
 148         }
 149     }
 150     if (flags & CONTEXT_DEBUG_REGISTERS)
 151     {
 152         if (get_debug_reg( pid, 0, &context->Dr0 ) == -1) goto error;
 153         if (get_debug_reg( pid, 1, &context->Dr1 ) == -1) goto error;
 154         if (get_debug_reg( pid, 2, &context->Dr2 ) == -1) goto error;
 155         if (get_debug_reg( pid, 3, &context->Dr3 ) == -1) goto error;
 156         if (get_debug_reg( pid, 6, &context->Dr6 ) == -1) goto error;
 157         if (get_debug_reg( pid, 7, &context->Dr7 ) == -1) goto error;
 158     }
 159     if (flags & CONTEXT_FLOATING_POINT)
 160     {
 161         /* we can use context->FloatSave directly as it is using the */
 162         /* correct structure (the same as fsave/frstor) */
 163         if (ptrace( PTRACE_GETFPREGS, pid, 0, &context->FloatSave ) == -1) goto error;
 164         context->FloatSave.Cr0NpxState = 0;  /* FIXME */
 165     }
 166     return;
 167  error:
 168     file_set_error();
 169 }
 170
 171
 172 /* set a thread context */
 173 static void set_thread_context( struct thread *thread, unsigned int flags, const CONTEXT *context )
 174 {
 175     int pid = get_ptrace_pid(thread);
 176     if (flags & CONTEXT_FULL)
 177     {
 178         struct kernel_user_regs_struct regs;
 179
 180         /* need to preserve some registers (at a minimum orig_eax must always be preserved) */
 181         if (ptrace( PTRACE_GETREGS, pid, 0, &regs ) == -1) goto error;
 182
 183         if (flags & CONTEXT_INTEGER)
 184         {
 185             regs.eax = context->Eax;
 186             regs.ebx = context->Ebx;
 187             regs.ecx = context->Ecx;
 188             regs.edx = context->Edx;
 189             regs.esi = context->Esi;
 190             regs.edi = context->Edi;
 191         }
 192         if (flags & CONTEXT_CONTROL)
 193         {
 194             regs.ebp = context->Ebp;
 195             regs.esp = context->Esp;
 196             regs.eip = context->Eip;
 197             regs.cs  = context->SegCs;
 198             regs.ss  = context->SegSs;
 199             regs.eflags = context->EFlags;
 200         }
 201         if (flags & CONTEXT_SEGMENTS)
 202         {
 203             regs.ds = context->SegDs;
 204             regs.es = context->SegEs;
 205             regs.fs = context->SegFs;
 206             regs.gs = context->SegGs;
 207         }
 208         if (ptrace( PTRACE_SETREGS, pid, 0, &regs ) == -1) goto error;
 209     }
 210     if (flags & CONTEXT_DEBUG_REGISTERS)
 211     {
 212         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(0), context->Dr0 ) == -1) goto error;
 213         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(1), context->Dr1 ) == -1) goto error;
 214         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(2), context->Dr2 ) == -1) goto error;
 215         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(3), context->Dr3 ) == -1) goto error;
 216         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(6), context->Dr6 ) == -1) goto error;
 217         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->Dr7 ) == -1) goto error;
 218     }
 219     if (flags & CONTEXT_FLOATING_POINT)
 220     {
 221         /* we can use context->FloatSave directly as it is using the */
 222         /* correct structure (the same as fsave/frstor) */
 223         if (ptrace( PTRACE_SETFPREGS, pid, 0, &context->FloatSave ) == -1) goto error;
 224     }
 225     return;
 226  error:
 227     file_set_error();
 228 }
 229
 230 #elif defined(__sun) || defined(__sun__)
 231
 232 /* retrieve a thread context */
 233 static void get_thread_context( struct thread *thread, unsigned int flags, CONTEXT *context )
 234 {
 235     int pid = get_ptrace_pid(thread);
 236     if (flags & CONTEXT_FULL)
 237     {
 238         struct regs regs;
 239         if (ptrace( PTRACE_GETREGS, pid, (int) &regs, 0 ) == -1) goto error;
 240         if (flags & CONTEXT_INTEGER)
 241         {
 242             context->Eax = regs.r_eax;
 243             context->Ebx = regs.r_ebx;
 244             context->Ecx = regs.r_ecx;
 245             context->Edx = regs.r_edx;
 246             context->Esi = regs.r_esi;
 247             context->Edi = regs.r_edi;
 248         }
 249         if (flags & CONTEXT_CONTROL)
 250         {
 251             context->Ebp    = regs.r_ebp;
 252             context->Esp    = regs.r_esp;
 253             context->Eip    = regs.r_eip;
 254             context->SegCs  = regs.r_cs & 0xffff;
 255             context->SegSs  = regs.r_ss & 0xffff;
 256             context->EFlags = regs.r_efl;
 257         }
 258         if (flags & CONTEXT_SEGMENTS)
 259         {
 260             context->SegDs = regs.r_ds & 0xffff;
 261             context->SegEs = regs.r_es & 0xffff;
 262             context->SegFs = regs.r_fs & 0xffff;
 263             context->SegGs = regs.r_gs & 0xffff;
 264         }
 265     }
 266     if (flags & CONTEXT_DEBUG_REGISTERS)
 267     {
 268         /* FIXME: How is this done on Solaris? */
 269     }
 270     if (flags & CONTEXT_FLOATING_POINT)
 271     {
 272         /* we can use context->FloatSave directly as it is using the */
 273         /* correct structure (the same as fsave/frstor) */
 274         if (ptrace( PTRACE_GETFPREGS, pid, (int) &context->FloatSave, 0 ) == -1) goto error;
 275         context->FloatSave.Cr0NpxState = 0;  /* FIXME */
 276     }
 277     return;
 278  error:
 279     file_set_error();
 280 }
 281
 282
 283 /* set a thread context */
 284 static void set_thread_context( struct thread *thread, unsigned int flags, const CONTEXT *context )
 285 {
 286     int pid = get_ptrace_pid(thread);
 287     if (flags & CONTEXT_FULL)
 288     {
 289         struct regs regs;
 290         if (((flags | CONTEXT_i386) & CONTEXT_FULL) != CONTEXT_FULL)
 291         {
 292             /* need to preserve some registers */
 293             if (ptrace( PTRACE_GETREGS, pid, (int) &regs, 0 ) == -1) goto error;
 294         }
 295         if (flags & CONTEXT_INTEGER)
 296         {
 297             regs.r_eax = context->Eax;
 298             regs.r_ebx = context->Ebx;
 299             regs.r_ecx = context->Ecx;
 300             regs.r_edx = context->Edx;
 301             regs.r_esi = context->Esi;
 302             regs.r_edi = context->Edi;
 303         }
 304         if (flags & CONTEXT_CONTROL)
 305         {
 306             regs.r_ebp = context->Ebp;
 307             regs.r_esp = context->Esp;
 308             regs.r_eip = context->Eip;
 309             regs.r_cs = context->SegCs;
 310             regs.r_ss = context->SegSs;
 311             regs.r_efl = context->EFlags;
 312         }
 313         if (flags & CONTEXT_SEGMENTS)
 314         {
 315             regs.r_ds = context->SegDs;
 316             regs.r_es = context->SegEs;
 317             regs.r_fs = context->SegFs;
 318             regs.r_gs = context->SegGs;
 319         }
 320         if (ptrace( PTRACE_SETREGS, pid, (int) &regs, 0 ) == -1) goto error;
 321     }
 322     if (flags & CONTEXT_DEBUG_REGISTERS)
 323     {
 324         /* FIXME: How is this done on Solaris? */
 325     }
 326     if (flags & CONTEXT_FLOATING_POINT)
 327     {
 328         /* we can use context->FloatSave directly as it is using the */
 329         /* correct structure (the same as fsave/frstor) */
 330         if (ptrace( PTRACE_SETFPREGS, pid, (int) &context->FloatSave, 0 ) == -1) goto error;
 331     }
 332     return;
 333  error:
 334     file_set_error();
 335 }
 336
 337 #elif defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__)
 338 #include <machine/reg.h>
 339
 340 /* retrieve a thread context */
 341 static void get_thread_context( struct thread *thread, unsigned int flags, CONTEXT *context )
 342 {
 343     int pid = get_ptrace_pid(thread);
 344     if (flags & CONTEXT_FULL)
 345     {
 346         struct reg regs;
 347         if (ptrace( PTRACE_GETREGS, pid, (caddr_t) &regs, 0 ) == -1) goto error;
 348         if (flags & CONTEXT_INTEGER)
 349         {
 350             context->Eax = regs.r_eax;
 351             context->Ebx = regs.r_ebx;
 352             context->Ecx = regs.r_ecx;
 353             context->Edx = regs.r_edx;
 354             context->Esi = regs.r_esi;
 355             context->Edi = regs.r_edi;
 356         }
 357         if (flags & CONTEXT_CONTROL)
 358         {
 359             context->Ebp    = regs.r_ebp;
 360             context->Esp    = regs.r_esp;
 361             context->Eip    = regs.r_eip;
 362             context->SegCs  = regs.r_cs & 0xffff;
 363             context->SegSs  = regs.r_ss & 0xffff;
 364             context->EFlags = regs.r_eflags;
 365         }
 366         if (flags & CONTEXT_SEGMENTS)
 367         {
 368             context->SegDs = regs.r_ds & 0xffff;
 369             context->SegEs = regs.r_es & 0xffff;
 370             context->SegFs = regs.r_fs & 0xffff;
 371             context->SegGs = regs.r_gs & 0xffff;
 372         }
 373     }
 374     if (flags & CONTEXT_DEBUG_REGISTERS)
 375     {
 376 #ifdef PTRACE_GETDBREGS
 377         struct dbreg dbregs;
 378         if (ptrace( PTRACE_GETDBREGS, pid, (caddr_t) &dbregs, 0 ) == -1)
 379                 goto error;
 380 #ifdef DBREG_DRX
 381         /* needed for FreeBSD, the structure fields have changed under 5.x */
 382         context->Dr0 = DBREG_DRX((&dbregs), 0);
 383         context->Dr1 = DBREG_DRX((&dbregs), 1);
 384         context->Dr2 = DBREG_DRX((&dbregs), 2);
 385         context->Dr3 = DBREG_DRX((&dbregs), 3);
 386         context->Dr6 = DBREG_DRX((&dbregs), 6);
 387         context->Dr7 = DBREG_DRX((&dbregs), 7);
 388 #else
 389         context->Dr0 = dbregs.dr0;
 390         context->Dr1 = dbregs.dr1;
 391         context->Dr2 = dbregs.dr2;
 392         context->Dr3 = dbregs.dr3;
 393         context->Dr6 = dbregs.dr6;
 394         context->Dr7 = dbregs.dr7;
 395 #endif
 396
 397 #endif
 398     }
 399     if (flags & CONTEXT_FLOATING_POINT)
 400     {
 401         /* we can use context->FloatSave directly as it is using the */
 402         /* correct structure (the same as fsave/frstor) */
 403         if (ptrace( PTRACE_GETFPREGS, pid, (caddr_t) &context->FloatSave, 0 ) == -1) goto error;
 404         context->FloatSave.Cr0NpxState = 0;  /* FIXME */
 405     }
 406     return;
 407  error:
 408     file_set_error();
 409 }
 410
 411
 412 /* set a thread context */
 413 static void set_thread_context( struct thread *thread, unsigned int flags, const CONTEXT *context )
 414 {
 415     int pid = get_ptrace_pid(thread);
 416     if (flags & CONTEXT_FULL)
 417     {
 418         struct reg regs;
 419         if (((flags | CONTEXT_i386) & CONTEXT_FULL) != CONTEXT_FULL)
 420         {
 421             /* need to preserve some registers */
 422             if (ptrace( PTRACE_GETREGS, pid, (caddr_t) &regs, 0 ) == -1) goto error;
 423         }
 424         if (flags & CONTEXT_INTEGER)
 425         {
 426             regs.r_eax = context->Eax;
 427             regs.r_ebx = context->Ebx;
 428             regs.r_ecx = context->Ecx;
 429             regs.r_edx = context->Edx;
 430             regs.r_esi = context->Esi;
 431             regs.r_edi = context->Edi;
 432         }
 433         if (flags & CONTEXT_CONTROL)
 434         {
 435             regs.r_ebp = context->Ebp;
 436             regs.r_esp = context->Esp;
 437             regs.r_eip = context->Eip;
 438             regs.r_cs = context->SegCs;
 439             regs.r_ss = context->SegSs;
 440             regs.r_eflags = context->EFlags;
 441         }
 442         if (flags & CONTEXT_SEGMENTS)
 443         {
 444             regs.r_ds = context->SegDs;
 445             regs.r_es = context->SegEs;
 446             regs.r_fs = context->SegFs;
 447             regs.r_gs = context->SegGs;
 448         }
 449         if (ptrace( PTRACE_SETREGS, pid, (caddr_t) &regs, 0 ) == -1) goto error;
 450     }
 451     if (flags & CONTEXT_DEBUG_REGISTERS)
 452     {
 453 #ifdef PTRACE_SETDBREGS
 454         struct dbreg dbregs;
 455 #ifdef DBREG_DRX
 456         /* needed for FreeBSD, the structure fields have changed under 5.x */
 457         DBREG_DRX((&dbregs), 0) = context->Dr0;
 458         DBREG_DRX((&dbregs), 1) = context->Dr1;
 459         DBREG_DRX((&dbregs), 2) = context->Dr2;
 460         DBREG_DRX((&dbregs), 3) = context->Dr3;
 461         DBREG_DRX((&dbregs), 4) = 0;
 462         DBREG_DRX((&dbregs), 5) = 0;
 463         DBREG_DRX((&dbregs), 6) = context->Dr6;
 464         DBREG_DRX((&dbregs), 7) = context->Dr7;
 465 #else
 466         dbregs.dr0 = context->Dr0;
 467         dbregs.dr1 = context->Dr1;
 468         dbregs.dr2 = context->Dr2;
 469         dbregs.dr3 = context->Dr3;
 470         dbregs.dr4 = 0;
 471         dbregs.dr5 = 0;
 472         dbregs.dr6 = context->Dr6;
 473         dbregs.dr7 = context->Dr7;
 474 #endif
 475         if (ptrace( PTRACE_SETDBREGS, pid, (caddr_t) &dbregs, 0 ) == -1)
 476                 goto error;
 477 #endif
 478     }
 479     if (flags & CONTEXT_FLOATING_POINT)
 480     {
 481         /* we can use context->FloatSave directly as it is using the */
 482         /* correct structure (the same as fsave/frstor) */
 483         if (ptrace( PTRACE_SETFPREGS, pid, (caddr_t) &context->FloatSave, 0 ) == -1) goto error;
 484     }
 485     return;
 486  error:
 487     file_set_error();
 488 }
 489
 490 #else  /* linux || __sun__ || __FreeBSD__ */
 491 #error You must implement get/set_thread_context for your platform
 492 #endif  /* linux || __sun__ || __FreeBSD__ */
 493
 494
 495 /* copy a context structure according to the flags */
 496 static void copy_context( CONTEXT *to, const CONTEXT *from, int flags )
 497 {
 498     if (flags & CONTEXT_CONTROL)
 499     {
 500         to->Ebp    = from->Ebp;
 501         to->Eip    = from->Eip;
 502         to->Esp    = from->Esp;
 503         to->SegCs  = from->SegCs;
 504         to->SegSs  = from->SegSs;
 505         to->EFlags = from->EFlags;
 506     }
 507     if (flags & CONTEXT_INTEGER)
 508     {
 509         to->Eax = from->Eax;
 510         to->Ebx = from->Ebx;
 511         to->Ecx = from->Ecx;
 512         to->Edx = from->Edx;
 513         to->Esi = from->Esi;
 514         to->Edi = from->Edi;
 515     }
 516     if (flags & CONTEXT_SEGMENTS)
 517     {
 518         to->SegDs = from->SegDs;
 519         to->SegEs = from->SegEs;
 520         to->SegFs = from->SegFs;
 521         to->SegGs = from->SegGs;
 522     }
 523     if (flags & CONTEXT_FLOATING_POINT)
 524     {
 525         to->FloatSave = from->FloatSave;
 526     }
 527     /* we don't bother copying the debug registers, since they */
 528     /* always need to be accessed by ptrace anyway */
 529 }
 530
 531 /* retrieve the current instruction pointer of a thread */
 532 void *get_thread_ip( struct thread *thread )
 533 {
 534     CONTEXT context;
 535     context.Eip = 0;
 536     if (suspend_for_ptrace( thread ))
 537     {
 538         get_thread_context( thread, CONTEXT_CONTROL, &context );
 539         resume_after_ptrace( thread );
 540     }
 541     return (void *)context.Eip;
 542 }
 543
 544 /* determine if we should continue the thread in single-step mode */
 545 int get_thread_single_step( struct thread *thread )
 546 {
 547     CONTEXT context;
 548     if (thread->context) return 0;  /* don't single-step inside exception event */
 549     get_thread_context( thread, CONTEXT_CONTROL, &context );
 550     return (context.EFlags & 0x100) != 0;
 551 }
 552
 553 /* send a signal to a specific thread */
 554 int tkill( int pid, int sig )
 555 {
 556 #ifdef __linux__
 557     int ret;
 558     __asm__( "pushl %%ebx\n\t"
 559              "movl %2,%%ebx\n\t"
 560              "int $0x80\n\t"
 561              "popl %%ebx\n\t"
 562              : "=a" (ret)
 563              : "0" (238) /*SYS_tkill*/, "r" (pid), "c" (sig) );
 564     if (ret > 0) return ret;
 565     errno = -ret;
 566     return -1;
 567 #else
 568     errno = ENOSYS;
 569     return -1;
 570 #endif
 571 }
 572
 573 /* retrieve the current context of a thread */
 574 DECL_HANDLER(get_thread_context)
 575 {
 576     struct thread *thread;
 577     void *data;
 578     int flags = req->flags & ~CONTEXT_i386;  /* get rid of CPU id */
 579
 580     if (get_reply_max_size() < sizeof(CONTEXT))
 581     {
 582         set_error( STATUS_INVALID_PARAMETER );
 583         return;
 584     }
 585     if (!(thread = get_thread_from_handle( req->handle, THREAD_GET_CONTEXT ))) return;
 586
 587     if ((data = set_reply_data_size( sizeof(CONTEXT) )))
 588     {
 589         /* copy incoming context into reply */
 590         memset( data, 0, sizeof(CONTEXT) );
 591         memcpy( data, get_req_data(), min( get_req_data_size(), sizeof(CONTEXT) ));
 592
 593         if (thread->context)  /* thread is inside an exception event */
 594         {
 595             copy_context( data, thread->context, flags );
 596             flags &= CONTEXT_DEBUG_REGISTERS;
 597         }
 598         if (flags && suspend_for_ptrace( thread ))
 599         {
 600             get_thread_context( thread, flags, data );
 601             resume_after_ptrace( thread );
 602         }
 603     }
 604     release_object( thread );
 605 }
 606
 607
 608 /* set the current context of a thread */
 609 DECL_HANDLER(set_thread_context)
 610 {
 611     struct thread *thread;
 612     int flags = req->flags & ~CONTEXT_i386;  /* get rid of CPU id */
 613
 614     if (get_req_data_size() < sizeof(CONTEXT))
 615     {
 616         set_error( STATUS_INVALID_PARAMETER );
 617         return;
 618     }
 619     if ((thread = get_thread_from_handle( req->handle, THREAD_SET_CONTEXT )))
 620     {
 621         if (thread->context)  /* thread is inside an exception event */
 622         {
 623             copy_context( thread->context, get_req_data(), flags );
 624             flags &= CONTEXT_DEBUG_REGISTERS;
 625         }
 626         if (flags && suspend_for_ptrace( thread ))
 627         {
 628             set_thread_context( thread, flags, get_req_data() );
 629             resume_after_ptrace( thread );
 630         }
 631         release_object( thread );
 632     }
 633 }
 634
 635 #endif  /* __i386__ */