dlls/ntdll/signal_i386.c

   1 /*
   2  * i386 signal handling routines
   3  *
   4  * Copyright 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 #ifdef __i386__
  22
  23 #include <errno.h>
  24 #include <signal.h>
  25 #include <stdlib.h>
  26 #include <stdarg.h>
  27 #include <stdio.h>
  28 #include <sys/types.h>
  29
  30 #include "ntstatus.h"
  31 #define WIN32_NO_STATUS
  32 #include "windef.h"
  33 #include "ntdll_misc.h"
  34 #include "wine/exception.h"
  35 #include "wine/debug.h"
  36
  37 WINE_DEFAULT_DEBUG_CHANNEL(seh);
  38
  39 struct x86_thread_data
  40 {
  41     DWORD              fs;            /* 1d4 TEB selector */
  42     DWORD              gs;            /* 1d8 libc selector; update winebuild if you move this! */
  43     DWORD              dr0;           /* 1dc debug registers */
  44     DWORD              dr1;           /* 1e0 */
  45     DWORD              dr2;           /* 1e4 */
  46     DWORD              dr3;           /* 1e8 */
  47     DWORD              dr6;           /* 1ec */
  48     DWORD              dr7;           /* 1f0 */
  49     void              *exit_frame;    /* 1f4 exit frame pointer */
  50 };
  51
  52 C_ASSERT( sizeof(struct x86_thread_data) <= 16 * sizeof(void *) );
  53 C_ASSERT( offsetof( TEB, GdiTebBatch ) + offsetof( struct x86_thread_data, gs ) == 0x1d8 );
  54 C_ASSERT( offsetof( TEB, GdiTebBatch ) + offsetof( struct x86_thread_data, exit_frame ) == 0x1f4 );
  55
  56 static inline struct x86_thread_data *x86_thread_data(void)
  57 {
  58     return (struct x86_thread_data *)&NtCurrentTeb()->GdiTebBatch;
  59 }
  60
  61 struct ldt_copy *__wine_ldt_copy = NULL;
  62
  63 /* Exception record for handling exceptions happening inside exception handlers */
  64 typedef struct
  65 {
  66     EXCEPTION_REGISTRATION_RECORD frame;
  67     EXCEPTION_REGISTRATION_RECORD *prevFrame;
  68 } EXC_NESTED_FRAME;
  69
  70 extern DWORD EXC_CallHandler( EXCEPTION_RECORD *record, EXCEPTION_REGISTRATION_RECORD *frame,
  71                               CONTEXT *context, EXCEPTION_REGISTRATION_RECORD **dispatcher,
  72                               PEXCEPTION_HANDLER handler, PEXCEPTION_HANDLER nested_handler );
  73
  74 /*******************************************************************
  75  *         is_valid_frame
  76  */
  77 static inline BOOL is_valid_frame( void *frame )
  78 {
  79     if ((ULONG_PTR)frame & 3) return FALSE;
  80     return (frame >= NtCurrentTeb()->Tib.StackLimit &&
  81             (void **)frame < (void **)NtCurrentTeb()->Tib.StackBase - 1);
  82 }
  83
  84 /*******************************************************************
  85  *         raise_handler
  86  *
  87  * Handler for exceptions happening inside a handler.
  88  */
  89 static DWORD raise_handler( EXCEPTION_RECORD *rec, EXCEPTION_REGISTRATION_RECORD *frame,
  90                             CONTEXT *context, EXCEPTION_REGISTRATION_RECORD **dispatcher )
  91 {
  92     if (rec->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND))
  93         return ExceptionContinueSearch;
  94     /* We shouldn't get here so we store faulty frame in dispatcher */
  95     *dispatcher = ((EXC_NESTED_FRAME*)frame)->prevFrame;
  96     return ExceptionNestedException;
  97 }
  98
  99
 100 /*******************************************************************
 101  *         unwind_handler
 102  *
 103  * Handler for exceptions happening inside an unwind handler.
 104  */
 105 static DWORD unwind_handler( EXCEPTION_RECORD *rec, EXCEPTION_REGISTRATION_RECORD *frame,
 106                              CONTEXT *context, EXCEPTION_REGISTRATION_RECORD **dispatcher )
 107 {
 108     if (!(rec->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND)))
 109         return ExceptionContinueSearch;
 110     /* We shouldn't get here so we store faulty frame in dispatcher */
 111     *dispatcher = ((EXC_NESTED_FRAME*)frame)->prevFrame;
 112     return ExceptionCollidedUnwind;
 113 }
 114
 115
 116 /**********************************************************************
 117  *           call_stack_handlers
 118  *
 119  * Call the stack handlers chain.
 120  */
 121 static NTSTATUS call_stack_handlers( EXCEPTION_RECORD *rec, CONTEXT *context )
 122 {
 123     EXCEPTION_REGISTRATION_RECORD *frame, *dispatch, *nested_frame;
 124     DWORD res;
 125
 126     frame = NtCurrentTeb()->Tib.ExceptionList;
 127     nested_frame = NULL;
 128     while (frame != (EXCEPTION_REGISTRATION_RECORD*)~0UL)
 129     {
 130         /* Check frame address */
 131         if (!is_valid_frame( frame ))
 132         {
 133             rec->ExceptionFlags |= EH_STACK_INVALID;
 134             break;
 135         }
 136
 137         /* Call handler */
 138         TRACE( "calling handler at %p code=%x flags=%x\n",
 139                frame->Handler, rec->ExceptionCode, rec->ExceptionFlags );
 140         res = EXC_CallHandler( rec, frame, context, &dispatch, frame->Handler, raise_handler );
 141         TRACE( "handler at %p returned %x\n", frame->Handler, res );
 142
 143         if (frame == nested_frame)
 144         {
 145             /* no longer nested */
 146             nested_frame = NULL;
 147             rec->ExceptionFlags &= ~EH_NESTED_CALL;
 148         }
 149
 150         switch(res)
 151         {
 152         case ExceptionContinueExecution:
 153             if (!(rec->ExceptionFlags & EH_NONCONTINUABLE)) return STATUS_SUCCESS;
 154             return STATUS_NONCONTINUABLE_EXCEPTION;
 155         case ExceptionContinueSearch:
 156             break;
 157         case ExceptionNestedException:
 158             if (nested_frame < dispatch) nested_frame = dispatch;
 159             rec->ExceptionFlags |= EH_NESTED_CALL;
 160             break;
 161         default:
 162             return STATUS_INVALID_DISPOSITION;
 163         }
 164         frame = frame->Prev;
 165     }
 166     return STATUS_UNHANDLED_EXCEPTION;
 167 }
 168
 169
 170 /*******************************************************************
 171  *              KiUserExceptionDispatcher (NTDLL.@)
 172  */
 173 NTSTATUS WINAPI dispatch_exception( EXCEPTION_RECORD *rec, CONTEXT *context )
 174 {
 175     NTSTATUS status;
 176     DWORD c;
 177
 178     TRACE( "code=%x flags=%x addr=%p ip=%08x tid=%04x\n",
 179            rec->ExceptionCode, rec->ExceptionFlags, rec->ExceptionAddress,
 180            context->Eip, GetCurrentThreadId() );
 181     for (c = 0; c < rec->NumberParameters; c++)
 182         TRACE( " info[%d]=%08lx\n", c, rec->ExceptionInformation[c] );
 183
 184     if (rec->ExceptionCode == EXCEPTION_WINE_STUB)
 185     {
 186         if (rec->ExceptionInformation[1] >> 16)
 187             MESSAGE( "wine: Call from %p to unimplemented function %s.%s, aborting\n",
 188                      rec->ExceptionAddress,
 189                      (char*)rec->ExceptionInformation[0], (char*)rec->ExceptionInformation[1] );
 190         else
 191             MESSAGE( "wine: Call from %p to unimplemented function %s.%ld, aborting\n",
 192                      rec->ExceptionAddress,
 193                      (char*)rec->ExceptionInformation[0], rec->ExceptionInformation[1] );
 194     }
 195     else if (rec->ExceptionCode == EXCEPTION_WINE_NAME_THREAD && rec->ExceptionInformation[0] == 0x1000)
 196     {
 197         WARN( "Thread %04x renamed to %s\n", (DWORD)rec->ExceptionInformation[2], debugstr_a((char *)rec->ExceptionInformation[1]) );
 198     }
 199     else if (rec->ExceptionCode == DBG_PRINTEXCEPTION_C)
 200     {
 201         WARN( "%s\n", debugstr_an((char *)rec->ExceptionInformation[1], rec->ExceptionInformation[0] - 1) );
 202     }
 203     else if (rec->ExceptionCode == DBG_PRINTEXCEPTION_WIDE_C)
 204     {
 205         WARN( "%s\n", debugstr_wn((WCHAR *)rec->ExceptionInformation[1], rec->ExceptionInformation[0] - 1) );
 206     }
 207     else
 208     {
 209         if (rec->ExceptionCode == STATUS_ASSERTION_FAILURE)
 210             ERR( "%s exception (code=%x) raised\n", debugstr_exception_code(rec->ExceptionCode), rec->ExceptionCode );
 211         else
 212             WARN( "%s exception (code=%x) raised\n", debugstr_exception_code(rec->ExceptionCode), rec->ExceptionCode );
 213
 214         TRACE(" eax=%08x ebx=%08x ecx=%08x edx=%08x esi=%08x edi=%08x\n",
 215               context->Eax, context->Ebx, context->Ecx,
 216               context->Edx, context->Esi, context->Edi );
 217         TRACE(" ebp=%08x esp=%08x cs=%04x ds=%04x es=%04x fs=%04x gs=%04x flags=%08x\n",
 218               context->Ebp, context->Esp, context->SegCs, context->SegDs,
 219               context->SegEs, context->SegFs, context->SegGs, context->EFlags );
 220     }
 221
 222     if (call_vectored_handlers( rec, context ) == EXCEPTION_CONTINUE_EXECUTION)
 223         NtContinue( context, FALSE );
 224
 225     if ((status = call_stack_handlers( rec, context )) == STATUS_SUCCESS)
 226         NtContinue( context, FALSE );
 227
 228     if (status != STATUS_UNHANDLED_EXCEPTION) RtlRaiseStatus( status );
 229     return NtRaiseException( rec, context, FALSE );
 230 }
 231
 232 __ASM_STDCALL_FUNC( KiUserExceptionDispatcher, 8,
 233                     "pushl 4(%esp)\n\t"
 234                     "pushl 4(%esp)\n\t"
 235                     "call " __ASM_STDCALL("dispatch_exception", 8) "\n\t"
 236                     "int3" )
 237
 238
 239 /*******************************************************************
 240  *              KiUserApcDispatcher (NTDLL.@)
 241  */
 242 void WINAPI KiUserApcDispatcher( CONTEXT *context, ULONG_PTR ctx, ULONG_PTR arg1, ULONG_PTR arg2,
 243                                  PNTAPCFUNC func )
 244 {
 245     func( ctx, arg1, arg2 );
 246     NtContinue( context, TRUE );
 247 }
 248
 249
 250 /***********************************************************************
 251  *           save_fpu
 252  *
 253  * Save the thread FPU context.
 254  */
 255 static inline void save_fpu( CONTEXT *context )
 256 {
 257 #ifdef __GNUC__
 258     struct
 259     {
 260         DWORD ControlWord;
 261         DWORD StatusWord;
 262         DWORD TagWord;
 263         DWORD ErrorOffset;
 264         DWORD ErrorSelector;
 265         DWORD DataOffset;
 266         DWORD DataSelector;
 267     }
 268     float_status;
 269
 270     context->ContextFlags |= CONTEXT_FLOATING_POINT;
 271     __asm__ __volatile__( "fnsave %0; fwait" : "=m" (context->FloatSave) );
 272
 273     /* Reset unmasked exceptions status to avoid firing an exception. */
 274     memcpy(&float_status, &context->FloatSave, sizeof(float_status));
 275     float_status.StatusWord &= float_status.ControlWord | 0xffffff80;
 276
 277     __asm__ __volatile__( "fldenv %0" : : "m" (float_status) );
 278 #endif
 279 }
 280
 281
 282 /***********************************************************************
 283  *           save_fpux
 284  *
 285  * Save the thread FPU extended context.
 286  */
 287 static inline void save_fpux( CONTEXT *context )
 288 {
 289 #ifdef __GNUC__
 290     /* we have to enforce alignment by hand */
 291     char buffer[sizeof(XSAVE_FORMAT) + 16];
 292     XSAVE_FORMAT *state = (XSAVE_FORMAT *)(((ULONG_PTR)buffer + 15) & ~15);
 293
 294     context->ContextFlags |= CONTEXT_EXTENDED_REGISTERS;
 295     __asm__ __volatile__( "fxsave %0" : "=m" (*state) );
 296     memcpy( context->ExtendedRegisters, state, sizeof(*state) );
 297 #endif
 298 }
 299
 300
 301 /***********************************************************************
 302  *              RtlCaptureContext (NTDLL.@)
 303  */
 304 __ASM_STDCALL_FUNC( RtlCaptureContext, 4,
 305                     "pushl %eax\n\t"
 306                     __ASM_CFI(".cfi_adjust_cfa_offset 4\n\t")
 307                     "movl 8(%esp),%eax\n\t"    /* context */
 308                     "movl $0x10007,(%eax)\n\t" /* context->ContextFlags */
 309                     "movw %gs,0x8c(%eax)\n\t"  /* context->SegGs */
 310                     "movw %fs,0x90(%eax)\n\t"  /* context->SegFs */
 311                     "movw %es,0x94(%eax)\n\t"  /* context->SegEs */
 312                     "movw %ds,0x98(%eax)\n\t"  /* context->SegDs */
 313                     "movl %edi,0x9c(%eax)\n\t" /* context->Edi */
 314                     "movl %esi,0xa0(%eax)\n\t" /* context->Esi */
 315                     "movl %ebx,0xa4(%eax)\n\t" /* context->Ebx */
 316                     "movl %edx,0xa8(%eax)\n\t" /* context->Edx */
 317                     "movl %ecx,0xac(%eax)\n\t" /* context->Ecx */
 318                     "movl 0(%ebp),%edx\n\t"
 319                     "movl %edx,0xb4(%eax)\n\t" /* context->Ebp */
 320                     "movl 4(%ebp),%edx\n\t"
 321                     "movl %edx,0xb8(%eax)\n\t" /* context->Eip */
 322                     "movw %cs,0xbc(%eax)\n\t"  /* context->SegCs */
 323                     "pushfl\n\t"
 324                     __ASM_CFI(".cfi_adjust_cfa_offset 4\n\t")
 325                     "popl 0xc0(%eax)\n\t"      /* context->EFlags */
 326                     __ASM_CFI(".cfi_adjust_cfa_offset -4\n\t")
 327                     "leal 8(%ebp),%edx\n\t"
 328                     "movl %edx,0xc4(%eax)\n\t" /* context->Esp */
 329                     "movw %ss,0xc8(%eax)\n\t"  /* context->SegSs */
 330                     "popl 0xb0(%eax)\n\t"      /* context->Eax */
 331                     __ASM_CFI(".cfi_adjust_cfa_offset -4\n\t")
 332                     "ret $4" )
 333
 334
 335 /*******************************************************************
 336  *              RtlUnwind (NTDLL.@)
 337  */
 338 void WINAPI DECLSPEC_HIDDEN __regs_RtlUnwind( EXCEPTION_REGISTRATION_RECORD* pEndFrame, PVOID targetIp,
 339                                               PEXCEPTION_RECORD pRecord, PVOID retval, CONTEXT *context )
 340 {
 341     EXCEPTION_RECORD record;
 342     EXCEPTION_REGISTRATION_RECORD *frame, *dispatch;
 343     DWORD res;
 344
 345     context->Eax = (DWORD)retval;
 346
 347     /* build an exception record, if we do not have one */
 348     if (!pRecord)
 349     {
 350         record.ExceptionCode    = STATUS_UNWIND;
 351         record.ExceptionFlags   = 0;
 352         record.ExceptionRecord  = NULL;
 353         record.ExceptionAddress = (void *)context->Eip;
 354         record.NumberParameters = 0;
 355         pRecord = &record;
 356     }
 357
 358     pRecord->ExceptionFlags |= EH_UNWINDING | (pEndFrame ? 0 : EH_EXIT_UNWIND);
 359
 360     TRACE( "code=%x flags=%x\n", pRecord->ExceptionCode, pRecord->ExceptionFlags );
 361     TRACE( "eax=%08x ebx=%08x ecx=%08x edx=%08x esi=%08x edi=%08x\n",
 362            context->Eax, context->Ebx, context->Ecx, context->Edx, context->Esi, context->Edi );
 363     TRACE( "ebp=%08x esp=%08x eip=%08x cs=%04x ds=%04x fs=%04x gs=%04x flags=%08x\n",
 364            context->Ebp, context->Esp, context->Eip, LOWORD(context->SegCs), LOWORD(context->SegDs),
 365            LOWORD(context->SegFs), LOWORD(context->SegGs), context->EFlags );
 366
 367     /* get chain of exception frames */
 368     frame = NtCurrentTeb()->Tib.ExceptionList;
 369     while ((frame != (EXCEPTION_REGISTRATION_RECORD*)~0UL) && (frame != pEndFrame))
 370     {
 371         /* Check frame address */
 372         if (pEndFrame && (frame > pEndFrame))
 373             raise_status( STATUS_INVALID_UNWIND_TARGET, pRecord );
 374
 375         if (!is_valid_frame( frame )) raise_status( STATUS_BAD_STACK, pRecord );
 376
 377         /* Call handler */
 378         TRACE( "calling handler at %p code=%x flags=%x\n",
 379                frame->Handler, pRecord->ExceptionCode, pRecord->ExceptionFlags );
 380         res = EXC_CallHandler( pRecord, frame, context, &dispatch, frame->Handler, unwind_handler );
 381         TRACE( "handler at %p returned %x\n", frame->Handler, res );
 382
 383         switch(res)
 384         {
 385         case ExceptionContinueSearch:
 386             break;
 387         case ExceptionCollidedUnwind:
 388             frame = dispatch;
 389             break;
 390         default:
 391             raise_status( STATUS_INVALID_DISPOSITION, pRecord );
 392             break;
 393         }
 394         frame = __wine_pop_frame( frame );
 395     }
 396     NtContinue( context, FALSE );
 397 }
 398 __ASM_STDCALL_FUNC( RtlUnwind, 16,
 399                     "pushl %ebp\n\t"
 400                     __ASM_CFI(".cfi_adjust_cfa_offset 4\n\t")
 401                     __ASM_CFI(".cfi_rel_offset %ebp,0\n\t")
 402                     "movl %esp,%ebp\n\t"
 403                     __ASM_CFI(".cfi_def_cfa_register %ebp\n\t")
 404                     "leal -(0x2cc+8)(%esp),%esp\n\t" /* sizeof(CONTEXT) + alignment */
 405                     "pushl %eax\n\t"
 406                     "leal 4(%esp),%eax\n\t"          /* context */
 407                     "xchgl %eax,(%esp)\n\t"
 408                     "call " __ASM_STDCALL("RtlCaptureContext",4) "\n\t"
 409                     "leal 24(%ebp),%eax\n\t"
 410                     "movl %eax,0xc4(%esp)\n\t"       /* context->Esp */
 411                     "pushl %esp\n\t"
 412                     "pushl 20(%ebp)\n\t"
 413                     "pushl 16(%ebp)\n\t"
 414                     "pushl 12(%ebp)\n\t"
 415                     "pushl 8(%ebp)\n\t"
 416                     "call " __ASM_STDCALL("__regs_RtlUnwind",20) "\n\t"
 417                     "leave\n\t"
 418                     __ASM_CFI(".cfi_def_cfa %esp,4\n\t")
 419                     __ASM_CFI(".cfi_same_value %ebp\n\t")
 420                     "ret $16" )  /* actually never returns */
 421
 422
 423 /*******************************************************************
 424  *              raise_exception_full_context
 425  *
 426  * Raise an exception with the full CPU context.
 427  */
 428 void raise_exception_full_context( EXCEPTION_RECORD *rec, CONTEXT *context )
 429 {
 430     save_fpu( context );
 431     save_fpux( context );
 432     /* FIXME: xstate */
 433     context->Dr0 = x86_thread_data()->dr0;
 434     context->Dr1 = x86_thread_data()->dr1;
 435     context->Dr2 = x86_thread_data()->dr2;
 436     context->Dr3 = x86_thread_data()->dr3;
 437     context->Dr6 = x86_thread_data()->dr6;
 438     context->Dr7 = x86_thread_data()->dr7;
 439     context->ContextFlags |= CONTEXT_DEBUG_REGISTERS;
 440
 441     RtlRaiseStatus( NtRaiseException( rec, context, TRUE ));
 442 }
 443
 444
 445 /***********************************************************************
 446  *              RtlRaiseException (NTDLL.@)
 447  */
 448 __ASM_STDCALL_FUNC( RtlRaiseException, 4,
 449                     "pushl %ebp\n\t"
 450                     __ASM_CFI(".cfi_adjust_cfa_offset 4\n\t")
 451                     __ASM_CFI(".cfi_rel_offset %ebp,0\n\t")
 452                     "movl %esp,%ebp\n\t"
 453                     __ASM_CFI(".cfi_def_cfa_register %ebp\n\t")
 454                     "leal -0x2cc(%esp),%esp\n\t"  /* sizeof(CONTEXT) */
 455                     "pushl %esp\n\t"              /* context */
 456                     "call " __ASM_STDCALL("RtlCaptureContext",4) "\n\t"
 457                     "movl 4(%ebp),%eax\n\t"       /* return address */
 458                     "movl 8(%ebp),%ecx\n\t"       /* rec */
 459                     "movl %eax,12(%ecx)\n\t"      /* rec->ExceptionAddress */
 460                     "leal 12(%ebp),%eax\n\t"
 461                     "movl %eax,0xc4(%esp)\n\t"    /* context->Esp */
 462                     "movl %esp,%eax\n\t"
 463                     "pushl %eax\n\t"
 464                     "pushl %ecx\n\t"
 465                     "call " __ASM_NAME("raise_exception_full_context") "\n\t"
 466                     "leave\n\t"
 467                     __ASM_CFI(".cfi_def_cfa %esp,4\n\t")
 468                     __ASM_CFI(".cfi_same_value %ebp\n\t")
 469                     "ret $4" )  /* actually never returns */
 470
 471
 472 /*************************************************************************
 473  *              RtlCaptureStackBackTrace (NTDLL.@)
 474  */
 475 USHORT WINAPI RtlCaptureStackBackTrace( ULONG skip, ULONG count, PVOID *buffer, ULONG *hash )
 476 {
 477     CONTEXT context;
 478     ULONG i;
 479     ULONG *frame;
 480
 481     RtlCaptureContext( &context );
 482     if (hash) *hash = 0;
 483     frame = (ULONG *)context.Ebp;
 484
 485     while (skip--)
 486     {
 487         if (!is_valid_frame( frame )) return 0;
 488         frame = (ULONG *)*frame;
 489     }
 490
 491     for (i = 0; i < count; i++)
 492     {
 493         if (!is_valid_frame( frame )) break;
 494         buffer[i] = (void *)frame[1];
 495         if (hash) *hash += frame[1];
 496         frame = (ULONG *)*frame;
 497     }
 498     return i;
 499 }
 500
 501
 502 /***********************************************************************
 503  *           signal_start_thread
 504  */
 505 __ASM_GLOBAL_FUNC( signal_start_thread,
 506                    "movl 4(%esp),%esi\n\t"   /* context */
 507                    "leal -12(%esi),%ecx\n\t"
 508                    /* clear the thread stack */
 509                    "andl $~0xfff,%ecx\n\t"   /* round down to page size */
 510                    "movl %fs:8,%edi\n\t"     /* NtCurrentTeb()->Tib.StackLimit */
 511                    "addl $0x1000,%edi\n\t"
 512                    "movl %edi,%esp\n\t"
 513                    "subl %edi,%ecx\n\t"
 514                    "xorl %eax,%eax\n\t"
 515                    "shrl $2,%ecx\n\t"
 516                    "rep; stosl\n\t"
 517                    /* switch to the initial context */
 518                    "leal -12(%esi),%esp\n\t"
 519                    "movl $1,4(%esp)\n\t"
 520                    "movl %esi,(%esp)\n\t"
 521                    "call " __ASM_STDCALL("NtContinue", 8) )
 522
 523 /**********************************************************************
 524  *              DbgBreakPoint   (NTDLL.@)
 525  */
 526 __ASM_STDCALL_FUNC( DbgBreakPoint, 0, "int $3; ret"
 527                     "\n\tnop; nop; nop; nop; nop; nop; nop; nop"
 528                     "\n\tnop; nop; nop; nop; nop; nop" );
 529
 530 /**********************************************************************
 531  *              DbgUserBreakPoint   (NTDLL.@)
 532  */
 533 __ASM_STDCALL_FUNC( DbgUserBreakPoint, 0, "int $3; ret"
 534                     "\n\tnop; nop; nop; nop; nop; nop; nop; nop"
 535                     "\n\tnop; nop; nop; nop; nop; nop" );
 536
 537 /**********************************************************************
 538  *           NtCurrentTeb   (NTDLL.@)
 539  */
 540 __ASM_STDCALL_FUNC( NtCurrentTeb, 0, ".byte 0x64\n\tmovl 0x18,%eax\n\tret" )
 541
 542
 543 /**************************************************************************
 544  *           _chkstk   (NTDLL.@)
 545  */
 546 __ASM_GLOBAL_FUNC( _chkstk,
 547                    "negl %eax\n\t"
 548                    "addl %esp,%eax\n\t"
 549                    "xchgl %esp,%eax\n\t"
 550                    "movl 0(%eax),%eax\n\t"  /* copy return address from old location */
 551                    "movl %eax,0(%esp)\n\t"
 552                    "ret" )
 553
 554 /**************************************************************************
 555  *           _alloca_probe   (NTDLL.@)
 556  */
 557 __ASM_GLOBAL_FUNC( _alloca_probe,
 558                    "negl %eax\n\t"
 559                    "addl %esp,%eax\n\t"
 560                    "xchgl %esp,%eax\n\t"
 561                    "movl 0(%eax),%eax\n\t"  /* copy return address from old location */
 562                    "movl %eax,0(%esp)\n\t"
 563                    "ret" )
 564
 565
 566 /**********************************************************************
 567  *              EXC_CallHandler   (internal)
 568  *
 569  * Some exception handlers depend on EBP to have a fixed position relative to
 570  * the exception frame.
 571  * Shrinker depends on (*1) doing what it does,
 572  * (*2) being the exact instruction it is and (*3) beginning with 0x64
 573  * (i.e. the %fs prefix to the movl instruction). It also depends on the
 574  * function calling the handler having only 5 parameters (*4).
 575  */
 576 __ASM_GLOBAL_FUNC( EXC_CallHandler,
 577                   "pushl %ebp\n\t"
 578                   __ASM_CFI(".cfi_adjust_cfa_offset 4\n\t")
 579                   __ASM_CFI(".cfi_rel_offset %ebp,0\n\t")
 580                   "movl %esp,%ebp\n\t"
 581                   __ASM_CFI(".cfi_def_cfa_register %ebp\n\t")
 582                    "pushl %ebx\n\t"
 583                    __ASM_CFI(".cfi_rel_offset %ebx,-4\n\t")
 584                    "movl 28(%ebp), %edx\n\t" /* ugly hack to pass the 6th param needed because of Shrinker */
 585                    "pushl 24(%ebp)\n\t"
 586                    "pushl 20(%ebp)\n\t"
 587                    "pushl 16(%ebp)\n\t"
 588                    "pushl 12(%ebp)\n\t"
 589                    "pushl 8(%ebp)\n\t"
 590                    "call " __ASM_NAME("call_exception_handler") "\n\t"
 591                    "popl %ebx\n\t"
 592                    __ASM_CFI(".cfi_same_value %ebx\n\t")
 593                    "leave\n"
 594                    __ASM_CFI(".cfi_def_cfa %esp,4\n\t")
 595                    __ASM_CFI(".cfi_same_value %ebp\n\t")
 596                    "ret" )
 597 __ASM_GLOBAL_FUNC(call_exception_handler,
 598                   "pushl %ebp\n\t"
 599                   __ASM_CFI(".cfi_adjust_cfa_offset 4\n\t")
 600                   __ASM_CFI(".cfi_rel_offset %ebp,0\n\t")
 601                   "movl %esp,%ebp\n\t"
 602                   __ASM_CFI(".cfi_def_cfa_register %ebp\n\t")
 603                   "subl $12,%esp\n\t"
 604                   "pushl 12(%ebp)\n\t"      /* make any exceptions in this... */
 605                   "pushl %edx\n\t"          /* handler be handled by... */
 606                   ".byte 0x64\n\t"
 607                   "pushl (0)\n\t"           /* nested_handler (passed in edx). */
 608                   ".byte 0x64\n\t"
 609                   "movl %esp,(0)\n\t"       /* push the new exception frame onto the exception stack. */
 610                   "pushl 20(%ebp)\n\t"
 611                   "pushl 16(%ebp)\n\t"
 612                   "pushl 12(%ebp)\n\t"
 613                   "pushl 8(%ebp)\n\t"
 614                   "movl 24(%ebp), %ecx\n\t" /* (*1) */
 615                   "call *%ecx\n\t"          /* call handler. (*2) */
 616                   ".byte 0x64\n\t"
 617                   "movl (0), %esp\n\t"      /* restore previous... (*3) */
 618                   ".byte 0x64\n\t"
 619                   "popl (0)\n\t"            /* exception frame. */
 620                   "movl %ebp, %esp\n\t"     /* restore saved stack, in case it was corrupted */
 621                   "popl %ebp\n\t"
 622                    __ASM_CFI(".cfi_def_cfa %esp,4\n\t")
 623                    __ASM_CFI(".cfi_same_value %ebp\n\t")
 624                   "ret $20" )            /* (*4) */
 625
 626 #endif  /* __i386__ */