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 <stdarg.h>
  31 #include <unistd.h>
  32 #ifdef HAVE_SYS_PTRACE_H
  33 # include <sys/ptrace.h>
  34 #endif
  35 #ifdef HAVE_SYS_PARAM_H
  36 # include <sys/param.h>
  37 #endif
  38
  39 #include "windef.h"
  40 #include "winbase.h"
  41
  42 #include "file.h"
  43 #include "thread.h"
  44 #include "request.h"
  45
  46 #ifndef PTRACE_PEEKUSER
  47 #  ifdef PTRACE_PEEKUSR /* libc5 uses USR not USER */
  48 #    define PTRACE_PEEKUSER PTRACE_PEEKUSR
  49 #  else
  50 #    define PTRACE_PEEKUSER PT_READ_U
  51 #  endif
  52 #endif
  53
  54 #ifndef PTRACE_POKEUSER
  55 #  ifdef PTRACE_POKEUSR /* libc5 uses USR not USER */
  56 #    define PTRACE_POKEUSER PTRACE_POKEUSR
  57 #  else
  58 #    define PTRACE_POKEUSER PT_WRITE_U
  59 #  endif
  60 #endif
  61
  62 #ifndef PTRACE_GETREGS
  63 #define PTRACE_GETREGS PT_GETREGS
  64 #endif
  65 #ifndef PTRACE_GETFPREGS
  66 #define PTRACE_GETFPREGS PT_GETFPREGS
  67 #endif
  68 #ifndef PTRACE_SETREGS
  69 #define PTRACE_SETREGS PT_SETREGS
  70 #endif
  71 #ifndef PTRACE_SETFPREGS
  72 #define PTRACE_SETFPREGS PT_SETFPREGS
  73 #endif
  74
  75 #ifdef PT_GETDBREGS
  76 #define PTRACE_GETDBREGS PT_GETDBREGS
  77 #endif
  78
  79 #ifdef PT_SETDBREGS
  80 #define PTRACE_SETDBREGS PT_SETDBREGS
  81 #endif
  82
  83 #ifdef linux
  84 #ifdef HAVE_SYS_USER_H
  85 # include <sys/user.h>
  86 #endif
  87
  88 /* user_regs definitions from asm/user.h */
  89 struct kernel_user_regs_struct
  90 {
  91     long ebx, ecx, edx, esi, edi, ebp, eax;
  92     unsigned short ds, __ds, es, __es;
  93     unsigned short fs, __fs, gs, __gs;
  94     long orig_eax, eip;
  95     unsigned short cs, __cs;
  96     long eflags, esp;
  97     unsigned short ss, __ss;
  98 };
  99
 100 /* debug register offset in struct user */
 101 #define DR_OFFSET(dr) ((int)((((struct user *)0)->u_debugreg) + (dr)))
 102
 103 /* retrieve a debug register */
 104 static inline int get_debug_reg( int pid, int num, DWORD *data )
 105 {
 106     int res;
 107     errno = 0;
 108     res = ptrace( PTRACE_PEEKUSER, pid, DR_OFFSET(num), 0 );
 109     if ((res == -1) && errno)
 110     {
 111         file_set_error();
 112         return -1;
 113     }
 114     *data = res;
 115     return 0;
 116 }
 117
 118 /* retrieve a thread context */
 119 static void get_thread_context( struct thread *thread, unsigned int flags, CONTEXT *context )
 120 {
 121     int pid = get_ptrace_pid(thread);
 122     if (flags & CONTEXT_FULL)
 123     {
 124         struct kernel_user_regs_struct regs;
 125         if (ptrace( PTRACE_GETREGS, pid, 0, &regs ) == -1) goto error;
 126         if (flags & CONTEXT_INTEGER)
 127         {
 128             context->Eax = regs.eax;
 129             context->Ebx = regs.ebx;
 130             context->Ecx = regs.ecx;
 131             context->Edx = regs.edx;
 132             context->Esi = regs.esi;
 133             context->Edi = regs.edi;
 134         }
 135         if (flags & CONTEXT_CONTROL)
 136         {
 137             context->Ebp    = regs.ebp;
 138             context->Esp    = regs.esp;
 139             context->Eip    = regs.eip;
 140             context->SegCs  = regs.cs;
 141             context->SegSs  = regs.ss;
 142             context->EFlags = regs.eflags;
 143         }
 144         if (flags & CONTEXT_SEGMENTS)
 145         {
 146             context->SegDs = regs.ds;
 147             context->SegEs = regs.es;
 148             context->SegFs = regs.fs;
 149             context->SegGs = regs.gs;
 150         }
 151     }
 152     if (flags & CONTEXT_DEBUG_REGISTERS)
 153     {
 154         if (get_debug_reg( pid, 0, &context->Dr0 ) == -1) goto error;
 155         if (get_debug_reg( pid, 1, &context->Dr1 ) == -1) goto error;
 156         if (get_debug_reg( pid, 2, &context->Dr2 ) == -1) goto error;
 157         if (get_debug_reg( pid, 3, &context->Dr3 ) == -1) goto error;
 158         if (get_debug_reg( pid, 6, &context->Dr6 ) == -1) goto error;
 159         if (get_debug_reg( pid, 7, &context->Dr7 ) == -1) goto error;
 160     }
 161     if (flags & CONTEXT_FLOATING_POINT)
 162     {
 163         /* we can use context->FloatSave directly as it is using the */
 164         /* correct structure (the same as fsave/frstor) */
 165         if (ptrace( PTRACE_GETFPREGS, pid, 0, &context->FloatSave ) == -1) goto error;
 166         context->FloatSave.Cr0NpxState = 0;  /* FIXME */
 167     }
 168     return;
 169  error:
 170     file_set_error();
 171 }
 172
 173
 174 /* set a thread context */
 175 static void set_thread_context( struct thread *thread, unsigned int flags, const CONTEXT *context )
 176 {
 177     int pid = get_ptrace_pid(thread);
 178     if (flags & CONTEXT_FULL)
 179     {
 180         struct kernel_user_regs_struct regs;
 181
 182         /* need to preserve some registers (at a minimum orig_eax must always be preserved) */
 183         if (ptrace( PTRACE_GETREGS, pid, 0, &regs ) == -1) goto error;
 184
 185         if (flags & CONTEXT_INTEGER)
 186         {
 187             regs.eax = context->Eax;
 188             regs.ebx = context->Ebx;
 189             regs.ecx = context->Ecx;
 190             regs.edx = context->Edx;
 191             regs.esi = context->Esi;
 192             regs.edi = context->Edi;
 193         }
 194         if (flags & CONTEXT_CONTROL)
 195         {
 196             regs.ebp = context->Ebp;
 197             regs.esp = context->Esp;
 198             regs.eip = context->Eip;
 199             regs.cs  = context->SegCs;
 200             regs.ss  = context->SegSs;
 201             regs.eflags = context->EFlags;
 202         }
 203         if (flags & CONTEXT_SEGMENTS)
 204         {
 205             regs.ds = context->SegDs;
 206             regs.es = context->SegEs;
 207             regs.fs = context->SegFs;
 208             regs.gs = context->SegGs;
 209         }
 210         if (ptrace( PTRACE_SETREGS, pid, 0, &regs ) == -1) goto error;
 211     }
 212     if (flags & CONTEXT_DEBUG_REGISTERS)
 213     {
 214         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(0), context->Dr0 ) == -1) goto error;
 215         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(1), context->Dr1 ) == -1) goto error;
 216         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(2), context->Dr2 ) == -1) goto error;
 217         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(3), context->Dr3 ) == -1) goto error;
 218         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(6), context->Dr6 ) == -1) goto error;
 219         if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->Dr7 ) == -1) goto error;
 220     }
 221     if (flags & CONTEXT_FLOATING_POINT)
 222     {
 223         /* we can use context->FloatSave directly as it is using the */
 224         /* correct structure (the same as fsave/frstor) */
 225         if (ptrace( PTRACE_SETFPREGS, pid, 0, &context->FloatSave ) == -1) goto error;
 226     }
 227     return;
 228  error:
 229     file_set_error();
 230 }
 231
 232 #elif defined(__sun) || defined(__sun__)
 233
 234 /* retrieve a thread context */
 235 static void get_thread_context( struct thread *thread, unsigned int flags, CONTEXT *context )
 236 {
 237     int pid = get_ptrace_pid(thread);
 238     if (flags & CONTEXT_FULL)
 239     {
 240         struct regs regs;
 241         if (ptrace( PTRACE_GETREGS, pid, (int) &regs, 0 ) == -1) goto error;
 242         if (flags & CONTEXT_INTEGER)
 243         {
 244             context->Eax = regs.r_eax;
 245             context->Ebx = regs.r_ebx;
 246             context->Ecx = regs.r_ecx;
 247             context->Edx = regs.r_edx;
 248             context->Esi = regs.r_esi;
 249             context->Edi = regs.r_edi;
 250         }
 251         if (flags & CONTEXT_CONTROL)
 252         {
 253             context->Ebp    = regs.r_ebp;
 254             context->Esp    = regs.r_esp;
 255             context->Eip    = regs.r_eip;
 256             context->SegCs  = regs.r_cs & 0xffff;
 257             context->SegSs  = regs.r_ss & 0xffff;
 258             context->EFlags = regs.r_efl;
 259         }
 260         if (flags & CONTEXT_SEGMENTS)
 261         {
 262             context->SegDs = regs.r_ds & 0xffff;
 263             context->SegEs = regs.r_es & 0xffff;
 264             context->SegFs = regs.r_fs & 0xffff;
 265             context->SegGs = regs.r_gs & 0xffff;
 266         }
 267     }
 268     if (flags & CONTEXT_DEBUG_REGISTERS)
 269     {
 270         /* FIXME: How is this done on Solaris? */
 271     }
 272     if (flags & CONTEXT_FLOATING_POINT)
 273     {
 274         /* we can use context->FloatSave directly as it is using the */
 275         /* correct structure (the same as fsave/frstor) */
 276         if (ptrace( PTRACE_GETFPREGS, pid, (int) &context->FloatSave, 0 ) == -1) goto error;
 277         context->FloatSave.Cr0NpxState = 0;  /* FIXME */
 278     }
 279     return;
 280  error:
 281     file_set_error();
 282 }
 283
 284
 285 /* set a thread context */
 286 static void set_thread_context( struct thread *thread, unsigned int flags, const CONTEXT *context )
 287 {
 288     int pid = get_ptrace_pid(thread);
 289     if (flags & CONTEXT_FULL)
 290     {
 291         struct regs regs;
 292         if (((flags | CONTEXT_i386) & CONTEXT_FULL) != CONTEXT_FULL)
 293         {
 294             /* need to preserve some registers */
 295             if (ptrace( PTRACE_GETREGS, pid, (int) &regs, 0 ) == -1) goto error;
 296         }
 297         if (flags & CONTEXT_INTEGER)
 298         {
 299             regs.r_eax = context->Eax;
 300             regs.r_ebx = context->Ebx;
 301             regs.r_ecx = context->Ecx;
 302             regs.r_edx = context->Edx;
 303             regs.r_esi = context->Esi;
 304             regs.r_edi = context->Edi;
 305         }
 306         if (flags & CONTEXT_CONTROL)
 307         {
 308             regs.r_ebp = context->Ebp;
 309             regs.r_esp = context->Esp;
 310             regs.r_eip = context->Eip;
 311             regs.r_cs = context->SegCs;
 312             regs.r_ss = context->SegSs;
 313             regs.r_efl = context->EFlags;
 314         }
 315         if (flags & CONTEXT_SEGMENTS)
 316         {
 317             regs.r_ds = context->SegDs;
 318             regs.r_es = context->SegEs;
 319             regs.r_fs = context->SegFs;
 320             regs.r_gs = context->SegGs;
 321         }
 322         if (ptrace( PTRACE_SETREGS, pid, (int) &regs, 0 ) == -1) goto error;
 323     }
 324     if (flags & CONTEXT_DEBUG_REGISTERS)
 325     {
 326         /* FIXME: How is this done on Solaris? */
 327     }
 328     if (flags & CONTEXT_FLOATING_POINT)
 329     {
 330         /* we can use context->FloatSave directly as it is using the */
 331         /* correct structure (the same as fsave/frstor) */
 332         if (ptrace( PTRACE_SETFPREGS, pid, (int) &context->FloatSave, 0 ) == -1) goto error;
 333     }
 334     return;
 335  error:
 336     file_set_error();
 337 }
 338
 339 #elif defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__)
 340 #include <machine/reg.h>
 341
 342 /* retrieve a thread context */
 343 static void get_thread_context( struct thread *thread, unsigned int flags, CONTEXT *context )
 344 {
 345     int pid = get_ptrace_pid(thread);
 346     if (flags & CONTEXT_FULL)
 347     {
 348         struct reg regs;
 349         if (ptrace( PTRACE_GETREGS, pid, (caddr_t) &regs, 0 ) == -1) goto error;
 350         if (flags & CONTEXT_INTEGER)
 351         {
 352             context->Eax = regs.r_eax;
 353             context->Ebx = regs.r_ebx;
 354             context->Ecx = regs.r_ecx;
 355             context->Edx = regs.r_edx;
 356             context->Esi = regs.r_esi;
 357             context->Edi = regs.r_edi;
 358         }
 359         if (flags & CONTEXT_CONTROL)
 360         {
 361             context->Ebp    = regs.r_ebp;
 362             context->Esp    = regs.r_esp;
 363             context->Eip    = regs.r_eip;
 364             context->SegCs  = regs.r_cs & 0xffff;
 365             context->SegSs  = regs.r_ss & 0xffff;
 366             context->EFlags = regs.r_eflags;
 367         }
 368         if (flags & CONTEXT_SEGMENTS)
 369         {
 370             context->SegDs = regs.r_ds & 0xffff;
 371             context->SegEs = regs.r_es & 0xffff;
 372             context->SegFs = regs.r_fs & 0xffff;
 373             context->SegGs = regs.r_gs & 0xffff;
 374         }
 375     }
 376     if (flags & CONTEXT_DEBUG_REGISTERS)
 377     {
 378 #ifdef PTRACE_GETDBREGS
 379         struct dbreg dbregs;
 380         if (ptrace( PTRACE_GETDBREGS, pid, (caddr_t) &dbregs, 0 ) == -1)
 381                 goto error;
 382 #ifdef DBREG_DRX
 383         /* needed for FreeBSD, the structure fields have changed under 5.x */
 384         context->Dr0 = DBREG_DRX((&dbregs), 0);
 385         context->Dr1 = DBREG_DRX((&dbregs), 1);
 386         context->Dr2 = DBREG_DRX((&dbregs), 2);
 387         context->Dr3 = DBREG_DRX((&dbregs), 3);
 388         context->Dr6 = DBREG_DRX((&dbregs), 6);
 389         context->Dr7 = DBREG_DRX((&dbregs), 7);
 390 #else
 391         context->Dr0 = dbregs.dr0;
 392         context->Dr1 = dbregs.dr1;
 393         context->Dr2 = dbregs.dr2;
 394         context->Dr3 = dbregs.dr3;
 395         context->Dr6 = dbregs.dr6;
 396         context->Dr7 = dbregs.dr7;
 397 #endif
 398
 399 #endif
 400     }
 401     if (flags & CONTEXT_FLOATING_POINT)
 402     {
 403         /* we can use context->FloatSave directly as it is using the */
 404         /* correct structure (the same as fsave/frstor) */
 405         if (ptrace( PTRACE_GETFPREGS, pid, (caddr_t) &context->FloatSave, 0 ) == -1) goto error;
 406         context->FloatSave.Cr0NpxState = 0;  /* FIXME */
 407     }
 408     return;
 409  error:
 410     file_set_error();
 411 }
 412
 413
 414 /* set a thread context */
 415 static void set_thread_context( struct thread *thread, unsigned int flags, const CONTEXT *context )
 416 {
 417     int pid = get_ptrace_pid(thread);
 418     if (flags & CONTEXT_FULL)
 419     {
 420         struct reg regs;
 421         if (((flags | CONTEXT_i386) & CONTEXT_FULL) != CONTEXT_FULL)
 422         {
 423             /* need to preserve some registers */
 424             if (ptrace( PTRACE_GETREGS, pid, (caddr_t) &regs, 0 ) == -1) goto error;
 425         }
 426         if (flags & CONTEXT_INTEGER)
 427         {
 428             regs.r_eax = context->Eax;
 429             regs.r_ebx = context->Ebx;
 430             regs.r_ecx = context->Ecx;
 431             regs.r_edx = context->Edx;
 432             regs.r_esi = context->Esi;
 433             regs.r_edi = context->Edi;
 434         }
 435         if (flags & CONTEXT_CONTROL)
 436         {
 437             regs.r_ebp = context->Ebp;
 438             regs.r_esp = context->Esp;
 439             regs.r_eip = context->Eip;
 440             regs.r_cs = context->SegCs;
 441             regs.r_ss = context->SegSs;
 442             regs.r_eflags = context->EFlags;
 443         }
 444         if (flags & CONTEXT_SEGMENTS)
 445         {
 446             regs.r_ds = context->SegDs;
 447             regs.r_es = context->SegEs;
 448             regs.r_fs = context->SegFs;
 449             regs.r_gs = context->SegGs;
 450         }
 451         if (ptrace( PTRACE_SETREGS, pid, (caddr_t) &regs, 0 ) == -1) goto error;
 452     }
 453     if (flags & CONTEXT_DEBUG_REGISTERS)
 454     {
 455 #ifdef PTRACE_SETDBREGS
 456         struct dbreg dbregs;
 457 #ifdef DBREG_DRX
 458         /* needed for FreeBSD, the structure fields have changed under 5.x */
 459         DBREG_DRX((&dbregs), 0) = context->Dr0;
 460         DBREG_DRX((&dbregs), 1) = context->Dr1;
 461         DBREG_DRX((&dbregs), 2) = context->Dr2;
 462         DBREG_DRX((&dbregs), 3) = context->Dr3;
 463         DBREG_DRX((&dbregs), 4) = 0;
 464         DBREG_DRX((&dbregs), 5) = 0;
 465         DBREG_DRX((&dbregs), 6) = context->Dr6;
 466         DBREG_DRX((&dbregs), 7) = context->Dr7;
 467 #else
 468         dbregs.dr0 = context->Dr0;
 469         dbregs.dr1 = context->Dr1;
 470         dbregs.dr2 = context->Dr2;
 471         dbregs.dr3 = context->Dr3;
 472         dbregs.dr4 = 0;
 473         dbregs.dr5 = 0;
 474         dbregs.dr6 = context->Dr6;
 475         dbregs.dr7 = context->Dr7;
 476 #endif
 477         if (ptrace( PTRACE_SETDBREGS, pid, (caddr_t) &dbregs, 0 ) == -1)
 478                 goto error;
 479 #endif
 480     }
 481     if (flags & CONTEXT_FLOATING_POINT)
 482     {
 483         /* we can use context->FloatSave directly as it is using the */
 484         /* correct structure (the same as fsave/frstor) */
 485         if (ptrace( PTRACE_SETFPREGS, pid, (caddr_t) &context->FloatSave, 0 ) == -1) goto error;
 486     }
 487     return;
 488  error:
 489     file_set_error();
 490 }
 491
 492 #else  /* linux || __sun__ || __FreeBSD__ */
 493 #error You must implement get/set_thread_context for your platform
 494 #endif  /* linux || __sun__ || __FreeBSD__ */
 495
 496
 497 /* copy a context structure according to the flags */
 498 static void copy_context( CONTEXT *to, const CONTEXT *from, int flags )
 499 {
 500     if (flags & CONTEXT_CONTROL)
 501     {
 502         to->Ebp    = from->Ebp;
 503         to->Eip    = from->Eip;
 504         to->Esp    = from->Esp;
 505         to->SegCs  = from->SegCs;
 506         to->SegSs  = from->SegSs;
 507         to->EFlags = from->EFlags;
 508     }
 509     if (flags & CONTEXT_INTEGER)
 510     {
 511         to->Eax = from->Eax;
 512         to->Ebx = from->Ebx;
 513         to->Ecx = from->Ecx;
 514         to->Edx = from->Edx;
 515         to->Esi = from->Esi;
 516         to->Edi = from->Edi;
 517     }
 518     if (flags & CONTEXT_SEGMENTS)
 519     {
 520         to->SegDs = from->SegDs;
 521         to->SegEs = from->SegEs;
 522         to->SegFs = from->SegFs;
 523         to->SegGs = from->SegGs;
 524     }
 525     if (flags & CONTEXT_FLOATING_POINT)
 526     {
 527         to->FloatSave = from->FloatSave;
 528     }
 529     /* we don't bother copying the debug registers, since they */
 530     /* always need to be accessed by ptrace anyway */
 531 }
 532
 533 /* retrieve the current instruction pointer of a thread */
 534 void *get_thread_ip( struct thread *thread )
 535 {
 536     CONTEXT context;
 537     context.Eip = 0;
 538     if (suspend_for_ptrace( thread ))
 539     {
 540         get_thread_context( thread, CONTEXT_CONTROL, &context );
 541         resume_after_ptrace( thread );
 542     }
 543     return (void *)context.Eip;
 544 }
 545
 546 /* determine if we should continue the thread in single-step mode */
 547 int get_thread_single_step( struct thread *thread )
 548 {
 549     CONTEXT context;
 550     if (thread->context) return 0;  /* don't single-step inside exception event */
 551     get_thread_context( thread, CONTEXT_CONTROL, &context );
 552     return (context.EFlags & 0x100) != 0;
 553 }
 554
 555 /* send a signal to a specific thread */
 556 int tkill( int pid, int sig )
 557 {
 558 #ifdef __linux__
 559     int ret;
 560     __asm__( "pushl %%ebx\n\t"
 561              "movl %2,%%ebx\n\t"
 562              "int $0x80\n\t"
 563              "popl %%ebx\n\t"
 564              : "=a" (ret)
 565              : "0" (238) /*SYS_tkill*/, "r" (pid), "c" (sig) );
 566     if (ret >= 0) return ret;
 567     errno = -ret;
 568     return -1;
 569 #else
 570     errno = ENOSYS;
 571     return -1;
 572 #endif
 573 }
 574
 575 /* retrieve the current context of a thread */
 576 DECL_HANDLER(get_thread_context)
 577 {
 578     struct thread *thread;
 579     void *data;
 580     int flags = req->flags & ~CONTEXT_i386;  /* get rid of CPU id */
 581
 582     if (get_reply_max_size() < sizeof(CONTEXT))
 583     {
 584         set_error( STATUS_INVALID_PARAMETER );
 585         return;
 586     }
 587     if (!(thread = get_thread_from_handle( req->handle, THREAD_GET_CONTEXT ))) return;
 588
 589     if ((data = set_reply_data_size( sizeof(CONTEXT) )))
 590     {
 591         /* copy incoming context into reply */
 592         memset( data, 0, sizeof(CONTEXT) );
 593         memcpy( data, get_req_data(), min( get_req_data_size(), sizeof(CONTEXT) ));
 594
 595         if (thread->context)  /* thread is inside an exception event */
 596         {
 597             copy_context( data, thread->context, flags );
 598             flags &= CONTEXT_DEBUG_REGISTERS;
 599         }
 600         if (flags && suspend_for_ptrace( thread ))
 601         {
 602             get_thread_context( thread, flags, data );
 603             resume_after_ptrace( thread );
 604         }
 605     }
 606     release_object( thread );
 607 }
 608
 609
 610 /* set the current context of a thread */
 611 DECL_HANDLER(set_thread_context)
 612 {
 613     struct thread *thread;
 614     int flags = req->flags & ~CONTEXT_i386;  /* get rid of CPU id */
 615
 616     if (get_req_data_size() < sizeof(CONTEXT))
 617     {
 618         set_error( STATUS_INVALID_PARAMETER );
 619         return;
 620     }
 621     if ((thread = get_thread_from_handle( req->handle, THREAD_SET_CONTEXT )))
 622     {
 623         if (thread->context)  /* thread is inside an exception event */
 624         {
 625             copy_context( thread->context, get_req_data(), flags );
 626             flags &= CONTEXT_DEBUG_REGISTERS;
 627         }
 628         if (flags && suspend_for_ptrace( thread ))
 629         {
 630             set_thread_context( thread, flags, get_req_data() );
 631             resume_after_ptrace( thread );
 632         }
 633         release_object( thread );
 634     }
 635 }
 636
 637 #endif  /* __i386__ */