reactos/ntoskrnl/rtl/i386/seh.s

   1 /* $Id$
   2  *
   3  * COPYRIGHT:         See COPYING in the top level directory
   4  * PROJECT:           ReactOS kernel
   5  * PURPOSE:           Runtime library exception support for IA-32
   6  * FILE:              ntoskrnl/rtl/i386/seh.s
   7  * PROGRAMER:         Casper S. Hornstrup (chorns@users.sourceforge.net)
   8  * NOTES:             This file is shared with lib/msvcrt/except/seh.s.
   9  *                    Please keep them in sync.
  10  */
  11
  12 #define ExceptionContinueExecution      0
  13 #define ExceptionContinueSearch         1
  14 #define ExceptionNestedException        2
  15 #define ExceptionCollidedUnwind         3
  16
  17 #define EXCEPTION_NONCONTINUABLE        0x01
  18 #define EXCEPTION_UNWINDING                     0x02
  19 #define EXCEPTION_EXIT_UNWIND           0x04
  20 #define EXCEPTION_STACK_INVALID         0x08
  21 #define EXCEPTION_NESTED_CALL           0x10
  22 #define EXCEPTION_TARGET_UNWIND         0x20
  23 #define EXCEPTION_COLLIDED_UNWIND       0x40
  24
  25 #define EXCEPTION_UNWIND_MODE \
  26 (  EXCEPTION_UNWINDING \
  27  | EXCEPTION_EXIT_UNWIND \
  28  | EXCEPTION_TARGET_UNWIND \
  29  | EXCEPTION_COLLIDED_UNWIND)
  30
  31 #define EREC_CODE               0x00
  32 #define EREC_FLAGS              0x04
  33 #define EREC_RECORD             0x08
  34 #define EREC_ADDRESS    0x0C
  35 #define EREC_NUMPARAMS  0x10
  36 #define EREC_INFO               0x14
  37
  38 #define TRYLEVEL_NONE    -1
  39 #define TRYLEVEL_INVALID -2
  40
  41 #define ER_STANDARDESP  -0x08
  42 #define ER_EPOINTERS    -0x04
  43 #define ER_PREVFRAME    0x00
  44 #define ER_HANDLER              0x04
  45 #define ER_SCOPETABLE   0x08
  46 #define ER_TRYLEVEL             0x0C
  47 #define ER_EBP                  0x10
  48
  49 #define ST_TRYLEVEL             0x00
  50 #define ST_FILTER               0x04
  51 #define ST_HANDLER              0x08
  52
  53 #define CONTEXT_EDI             0x9C
  54 #define CONTEXT_EBX             0xA4
  55 #define CONTEXT_EIP             0xB8
  56
  57 .globl __local_unwind2
  58 .globl __except_handler3
  59
  60 // EAX = value to print
  61 _do_debug:
  62         pushal
  63         pushl   %eax
  64         call    _MsvcrtDebug@4
  65         popal
  66         ret
  67
  68 #define LU2_TRYLEVEL    0x08
  69 #define LU2_REGFRAME    0x04
  70
  71 //
  72 // void
  73 // _local_unwind2(PEXCEPTION_REGISTRATION RegistrationFrame,
  74 //                            LONG TryLevel)
  75 //
  76 // Parameters:
  77 //   [EDX+08h] - PEXCEPTION_REGISTRATION RegistrationFrame
  78 //   [EDX+04h] - LONG TryLevel
  79 // Registers:
  80 //   EBP - EBP of call frame we are unwinding
  81 // Returns:
  82 //   Nothing
  83 // Notes:
  84 //   Run all termination handlers for a call frame from the current
  85 //   try-level up to (but not including) the given stop try-level.
  86 __local_unwind2:
  87     // Setup our call frame so we can access parameters using EDX
  88     //pushl    %ebp
  89     movl     %esp, %edx
  90
  91     // FIXME: Setup an EXCEPTION_REGISTRATION entry to protect the
  92     // unwinding in case something goes wrong
  93
  94 .lu2_next_scope:
  95
  96     // Keep a pointer to the exception registration in EBX
  97     movl     LU2_REGFRAME(%edx), %ebx
  98
  99     // If we have reached the end of the chain or we're asked to stop here
 100     // by the caller then exit
 101     movl     ER_TRYLEVEL(%ebx), %eax
 102
 103     cmpl     $-1, %eax
 104     je       .lu2_done
 105
 106     cmpl     LU2_TRYLEVEL(%edx), %eax
 107     je       .lu2_done
 108
 109     // Keep a pointer to the scopetable in ESI
 110     movl     ER_SCOPETABLE(%ebx), %esi
 111
 112     // Compute the offset of the entry in the scopetable that describes
 113     // the scope that is to be unwound. Put the offset in EDI.
 114     movl        ST_TRYLEVEL(%esi), %edi
 115     lea     (%edi, %edi, 2), %edi
 116     shll    $2, %edi
 117     addl    %esi, %edi
 118
 119     // If this is not a termination handler then skip it
 120     cmpl     $0, ST_FILTER(%edi)
 121     jne      .lu2_next_scope
 122
 123     // Save the previous try-level in the exception registration structure
 124     movl     ST_TRYLEVEL(%edi), %eax
 125     movl     %eax, ER_TRYLEVEL(%ebx)
 126
 127     // Fetch the address of the termination handler
 128     movl     ST_HANDLER(%edi), %eax
 129
 130     // Termination handlers may trash all registers so save the
 131     // important ones and then call the handler
 132     pushl    %edx
 133     call         *%eax
 134
 135         // Get our base pointer back
 136     popl     %edx
 137
 138     jmp      .lu2_next_scope
 139
 140 .lu2_done:
 141
 142     // FIXME: Tear down the EXCEPTION_REGISTRATION entry setup to protect
 143     // the unwinding
 144
 145         //movl  %esi, %esp
 146     //popl      %ebp
 147     ret
 148
 149 #define EH3_DISPCONTEXT 0x14
 150 #define EH3_CONTEXT             0x10
 151 #define EH3_REGFRAME    0x0C
 152 #define EH3_ERECORD             0x08
 153
 154 // Parameters:
 155 //   [ESP+14h] - PVOID DispatcherContext
 156 //   [ESP+10h] - PCONTEXT Context
 157 //   [ESP+0Ch] - PEXCEPTION_REGISTRATION RegistrationFrame
 158 //   [ESP+08h] - PEXCEPTION_RECORD ExceptionRecord
 159 // Registers:
 160 //   Unknown
 161 // Returns:
 162 //   EXCEPTION_DISPOSITION - How this handler handled the exception
 163 // Notes:
 164 //   Try to find an exception handler that will handle the exception.
 165 //   Traverse the entries in the scopetable that is associated with the
 166 //   exception registration passed as a parameter to this function.
 167 //   If an exception handler that will handle the exception is found, it
 168 //   is called and this function never returns
 169 __except_handler3:
 170     // Setup our call frame so we can access parameters using EBP
 171     pushl    %ebp                               // Standard ESP in frame (considered part of EXCEPTION_REGISTRATION)
 172     movl     %esp, %ebp
 173
 174     // Don't trust the direction flag to be cleared
 175     cld
 176
 177     // Either we're called to handle an exception or we're called to unwind
 178     movl        EH3_ERECORD(%ebp), %eax
 179     testl       $EXCEPTION_UNWIND_MODE, EREC_FLAGS(%eax)
 180     jnz         .eh3_unwind
 181
 182     // Keep a pointer to the exception registration in EBX
 183     movl     EH3_REGFRAME(%ebp), %ebx
 184
 185     // Build an EXCEPTION_POINTERS structure on the stack and store it's
 186     // address in the EXCEPTION_REGISTRATION structure
 187     movl     EH3_CONTEXT(%esp), %eax
 188     pushl    %ebx                                               // Registration frame
 189     pushl    %eax                                               // Context
 190     movl     %esp, ER_EPOINTERS(%ebx)   // Pointer to EXCEPTION_REGISTRATION on the stack
 191
 192     // Keep current try-level in EDI
 193     movl     ER_TRYLEVEL(%ebx), %edi
 194
 195     // Keep a pointer to the scopetable in ESI
 196     movl     ER_SCOPETABLE(%ebx), %esi
 197
 198 .eh3_next_scope:
 199
 200     // If we have reached the end of the chain then exit
 201     cmpl     $-1, %edi
 202     je       .eh3_search
 203
 204     // Compute the offset of the entry in the scopetable and store
 205     // the absolute address in EAX
 206     lea     (%edi, %edi, 2), %eax
 207     shll    $2, %eax
 208     addl    %esi, %eax
 209
 210     // Fetch the address of the filter routine
 211     movl     ST_FILTER(%eax), %eax
 212
 213     // If this is a termination handler then skip it
 214     cmpl     $0, %eax
 215     je       .eh3_continue
 216
 217     // Filter routines may trash all registers so save the important
 218     // ones before restoring the call frame ebp and calling the handler
 219     pushl       %ebp
 220     pushl       %edi                            // Stop try-level
 221     lea         ER_EBP(%ebx), %ebp
 222     call        *%eax
 223     popl        %edi                            // Stop try-level
 224     popl        %ebp
 225
 226     // Reload EBX with registration frame address
 227     movl        EH3_REGFRAME(%ebp), %ebx
 228
 229     // Be more flexible here by checking if the return value is less than
 230     // zero, equal to zero, or larger than zero instead of the defined
 231     // values:
 232     //   -1 (EXCEPTION_CONTINUE_EXECUTION)
 233     //    0 (EXCEPTION_CONTINUE_SEARCH)
 234     //   +1 (EXCEPTION_EXECUTE_HANDLER)
 235     orl      %eax, %eax
 236     jz       .eh3_continue
 237     js       .eh3_dismiss
 238
 239     // Filter returned: EXCEPTION_EXECUTE_HANDLER
 240
 241     // Ask the OS to perform global unwinding.
 242     pushl       %edi            // Save stop try-level
 243     pushl       %ebx            // Save registration frame address
 244     pushl       %ebx            // Registration frame address
 245     call        __global_unwind2
 246     popl        %eax            // Remove parameter to __global_unwind2
 247     popl        %ebx            // Restore registration frame address
 248     popl        %edi            // Restore stop try-level
 249
 250     // Change the context structure so _except_finish is called in the
 251     // correct context since we return ExceptionContinueExecution.
 252     movl     EH3_CONTEXT(%ebp), %eax
 253
 254     movl     %edi, CONTEXT_EDI(%eax)            // Stop try-level
 255     movl     %ebx, CONTEXT_EBX(%eax)            // Registration frame address
 256     movl     $_except_finish, CONTEXT_EIP(%eax)
 257
 258     movl     $ExceptionContinueExecution, %eax
 259     jmp      .eh3_return
 260
 261     // Filter returned: EXCEPTION_CONTINUE_SEARCH
 262 .eh3_continue:
 263
 264     // Reload ESI because the filter routine may have trashed it
 265     movl     ER_SCOPETABLE(%ebx), %esi
 266
 267     // Go one try-level closer to the top
 268     lea      (%edi, %edi, 2), %edi
 269     shll     $2, %edi
 270     addl     %esi, %edi
 271     movl     ST_TRYLEVEL(%edi), %edi
 272
 273     jmp      .eh3_next_scope
 274
 275     // Filter returned: EXCEPTION_CONTINUE_EXECUTION
 276     // Continue execution like nothing happened
 277 .eh3_dismiss:
 278     movl     $ExceptionContinueExecution, %eax
 279     jmp      .eh3_return
 280
 281     // Tell the OS to search for another handler that will handle the exception
 282 .eh3_search:
 283
 284     movl     $ExceptionContinueSearch, %eax
 285     jmp      .eh3_return
 286
 287     // Perform local unwinding
 288 .eh3_unwind:
 289
 290     movl     $ExceptionContinueSearch, %eax
 291     testl    $EXCEPTION_TARGET_UNWIND, EREC_FLAGS(%eax)
 292     jnz      .eh3_return
 293
 294         // Save some important registers
 295     pushl       %ebp
 296
 297     lea          ER_EBP(%ebx), %ebp
 298     pushl    $-1
 299     pushl    %ebx
 300     call     __local_unwind2
 301     addl     $8, %esp
 302
 303         // Restore some important registers
 304     popl     %ebp
 305
 306     movl     $ExceptionContinueSearch, %eax
 307
 308     // Get me out of here
 309 .eh3_return:
 310
 311         movl    %ebp, %esp
 312     popl        %ebp
 313     ret
 314
 315 // Parameters:
 316 //   None
 317 // Registers:
 318 //   EBX - Pointer to exception registration structure
 319 //   EDI - Stop try-level
 320 // Returns:
 321 //   -
 322 // Notes:
 323 //   -
 324 _except_finish:
 325
 326     // Setup EBP for the exception handler. By doing this the exception
 327     // handler can access local variables as normal
 328     lea         ER_EBP(%ebx), %ebp
 329
 330         // Save some important registers
 331     pushl       %ebp
 332     pushl       %ebx
 333     pushl       %edi
 334
 335     // Stop try-level
 336     pushl       %edi
 337
 338     // Pointer to exception registration structure
 339     pushl    %ebx
 340     call     __local_unwind2
 341     addl     $8, %esp
 342
 343         // Restore some important registers
 344     popl     %edi
 345     popl     %ebx
 346     popl     %ebp
 347
 348     // Keep a pointer to the scopetable in ESI
 349     movl     ER_SCOPETABLE(%ebx), %esi
 350
 351     // Compute the offset of the entry in the scopetable and store
 352     // the absolute address in EDI
 353     lea     (%edi, %edi, 2), %edi
 354     shll    $2, %edi
 355     addl    %esi, %edi
 356
 357     // Set the current try-level to the previous try-level and call
 358     // the exception handler
 359     movl     ST_TRYLEVEL(%edi), %eax
 360     movl     %eax, ER_TRYLEVEL(%ebx)
 361     movl     ST_HANDLER(%edi), %eax
 362
 363     call    *%eax
 364
 365     // We should never get here
 366     ret