1//===--------------------------- Unwind-seh.cpp ---------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9//  Implements SEH-based Itanium C++ exceptions.
10//
11//===----------------------------------------------------------------------===//
12
13#include "config.h"
14
15#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
16
17#include <unwind.h>
18
19#include <stdint.h>
20#include <stdbool.h>
21#include <stdlib.h>
22
23#include <windef.h>
24#include <excpt.h>
25#include <winnt.h>
26#include <ntstatus.h>
27
28#include "libunwind_ext.h"
29#include "UnwindCursor.hpp"
30
31using namespace libunwind;
32
33#define STATUS_USER_DEFINED (1u << 29)
34
35#define STATUS_GCC_MAGIC  (('G' << 16) | ('C' << 8) | 'C')
36
37#define MAKE_CUSTOM_STATUS(s, c) \
38  ((NTSTATUS)(((s) << 30) | STATUS_USER_DEFINED | (c)))
39#define MAKE_GCC_EXCEPTION(c) \
40  MAKE_CUSTOM_STATUS(STATUS_SEVERITY_SUCCESS, STATUS_GCC_MAGIC | ((c) << 24))
41
42/// SEH exception raised by libunwind when the program calls
43/// \c _Unwind_RaiseException.
44#define STATUS_GCC_THROW MAKE_GCC_EXCEPTION(0) // 0x20474343
45/// SEH exception raised by libunwind to initiate phase 2 of exception
46/// handling.
47#define STATUS_GCC_UNWIND MAKE_GCC_EXCEPTION(1) // 0x21474343
48
49/// Class of foreign exceptions based on unrecognized SEH exceptions.
50static const uint64_t kSEHExceptionClass = 0x434C4E4753454800; // CLNGSEH\0
51
52/// Exception cleanup routine used by \c _GCC_specific_handler to
53/// free foreign exceptions.
54static void seh_exc_cleanup(_Unwind_Reason_Code urc, _Unwind_Exception *exc) {
55  (void)urc;
56  if (exc->exception_class != kSEHExceptionClass)
57    _LIBUNWIND_ABORT("SEH cleanup called on non-SEH exception");
58  free(exc);
59}
60
61static int __unw_init_seh(unw_cursor_t *cursor, CONTEXT *ctx);
62static DISPATCHER_CONTEXT *__unw_seh_get_disp_ctx(unw_cursor_t *cursor);
63static void __unw_seh_set_disp_ctx(unw_cursor_t *cursor,
64                                   DISPATCHER_CONTEXT *disp);
65
66/// Common implementation of SEH-style handler functions used by Itanium-
67/// style frames.  Depending on how and why it was called, it may do one of:
68///  a) Delegate to the given Itanium-style personality function; or
69///  b) Initiate a collided unwind to halt unwinding.
70_LIBUNWIND_EXPORT EXCEPTION_DISPOSITION
71_GCC_specific_handler(PEXCEPTION_RECORD ms_exc, PVOID frame, PCONTEXT ms_ctx,
72                      DISPATCHER_CONTEXT *disp, __personality_routine pers) {
73  unw_cursor_t cursor;
74  _Unwind_Exception *exc;
75  _Unwind_Action action;
76  struct _Unwind_Context *ctx = nullptr;
77  _Unwind_Reason_Code urc;
78  uintptr_t retval, target;
79  bool ours = false;
80
81  _LIBUNWIND_TRACE_UNWINDING("_GCC_specific_handler(%#010lx(%lx), %p)",
82                             ms_exc->ExceptionCode, ms_exc->ExceptionFlags,
83                             (void *)frame);
84  if (ms_exc->ExceptionCode == STATUS_GCC_UNWIND) {
85    if (IS_TARGET_UNWIND(ms_exc->ExceptionFlags)) {
86      // Set up the upper return value (the lower one and the target PC
87      // were set in the call to RtlUnwindEx()) for the landing pad.
88#ifdef __x86_64__
89      disp->ContextRecord->Rdx = ms_exc->ExceptionInformation[3];
90#elif defined(__arm__)
91      disp->ContextRecord->R1 = ms_exc->ExceptionInformation[3];
92#elif defined(__aarch64__)
93      disp->ContextRecord->X1 = ms_exc->ExceptionInformation[3];
94#endif
95    }
96    // This is the collided unwind to the landing pad. Nothing to do.
97    return ExceptionContinueSearch;
98  }
99
100  if (ms_exc->ExceptionCode == STATUS_GCC_THROW) {
101    // This is (probably) a libunwind-controlled exception/unwind. Recover the
102    // parameters which we set below, and pass them to the personality function.
103    ours = true;
104    exc = (_Unwind_Exception *)ms_exc->ExceptionInformation[0];
105    if (!IS_UNWINDING(ms_exc->ExceptionFlags) && ms_exc->NumberParameters > 1) {
106      ctx = (struct _Unwind_Context *)ms_exc->ExceptionInformation[1];
107      action = (_Unwind_Action)ms_exc->ExceptionInformation[2];
108    }
109  } else {
110    // Foreign exception.
111    exc = (_Unwind_Exception *)malloc(sizeof(_Unwind_Exception));
112    exc->exception_class = kSEHExceptionClass;
113    exc->exception_cleanup = seh_exc_cleanup;
114    memset(exc->private_, 0, sizeof(exc->private_));
115  }
116  if (!ctx) {
117    __unw_init_seh(&cursor, disp->ContextRecord);
118    __unw_seh_set_disp_ctx(&cursor, disp);
119    __unw_set_reg(&cursor, UNW_REG_IP, disp->ControlPc - 1);
120    ctx = (struct _Unwind_Context *)&cursor;
121
122    if (!IS_UNWINDING(ms_exc->ExceptionFlags)) {
123      if (ours && ms_exc->NumberParameters > 1)
124        action =  (_Unwind_Action)(_UA_CLEANUP_PHASE | _UA_FORCE_UNWIND);
125      else
126        action = _UA_SEARCH_PHASE;
127    } else {
128      if (ours && ms_exc->ExceptionInformation[1] == (ULONG_PTR)frame)
129        action = (_Unwind_Action)(_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME);
130      else
131        action = _UA_CLEANUP_PHASE;
132    }
133  }
134
135  _LIBUNWIND_TRACE_UNWINDING("_GCC_specific_handler() calling personality "
136                             "function %p(1, %d, %llx, %p, %p)",
137                             (void *)pers, action, exc->exception_class,
138                             (void *)exc, (void *)ctx);
139  urc = pers(1, action, exc->exception_class, exc, ctx);
140  _LIBUNWIND_TRACE_UNWINDING("_GCC_specific_handler() personality returned %d", urc);
141  switch (urc) {
142  case _URC_CONTINUE_UNWIND:
143    // If we're in phase 2, and the personality routine said to continue
144    // at the target frame, we're in real trouble.
145    if (action & _UA_HANDLER_FRAME)
146      _LIBUNWIND_ABORT("Personality continued unwind at the target frame!");
147    return ExceptionContinueSearch;
148  case _URC_HANDLER_FOUND:
149    // If we were called by __libunwind_seh_personality(), indicate that
150    // a handler was found; otherwise, initiate phase 2 by unwinding.
151    if (ours && ms_exc->NumberParameters > 1)
152      return 4 /* ExecptionExecuteHandler in mingw */;
153    // This should never happen in phase 2.
154    if (IS_UNWINDING(ms_exc->ExceptionFlags))
155      _LIBUNWIND_ABORT("Personality indicated exception handler in phase 2!");
156    exc->private_[1] = (ULONG_PTR)frame;
157    if (ours) {
158      ms_exc->NumberParameters = 4;
159      ms_exc->ExceptionInformation[1] = (ULONG_PTR)frame;
160    }
161    // FIXME: Indicate target frame in foreign case!
162    // phase 2: the clean up phase
163    RtlUnwindEx(frame, (PVOID)disp->ControlPc, ms_exc, exc, ms_ctx, disp->HistoryTable);
164    _LIBUNWIND_ABORT("RtlUnwindEx() failed");
165  case _URC_INSTALL_CONTEXT: {
166    // If we were called by __libunwind_seh_personality(), indicate that
167    // a handler was found; otherwise, it's time to initiate a collided
168    // unwind to the target.
169    if (ours && !IS_UNWINDING(ms_exc->ExceptionFlags) && ms_exc->NumberParameters > 1)
170      return 4 /* ExecptionExecuteHandler in mingw */;
171    // This should never happen in phase 1.
172    if (!IS_UNWINDING(ms_exc->ExceptionFlags))
173      _LIBUNWIND_ABORT("Personality installed context during phase 1!");
174#ifdef __x86_64__
175    exc->private_[2] = disp->TargetIp;
176    __unw_get_reg(&cursor, UNW_X86_64_RAX, &retval);
177    __unw_get_reg(&cursor, UNW_X86_64_RDX, &exc->private_[3]);
178#elif defined(__arm__)
179    exc->private_[2] = disp->TargetPc;
180    __unw_get_reg(&cursor, UNW_ARM_R0, &retval);
181    __unw_get_reg(&cursor, UNW_ARM_R1, &exc->private_[3]);
182#elif defined(__aarch64__)
183    exc->private_[2] = disp->TargetPc;
184    __unw_get_reg(&cursor, UNW_ARM64_X0, &retval);
185    __unw_get_reg(&cursor, UNW_ARM64_X1, &exc->private_[3]);
186#endif
187    __unw_get_reg(&cursor, UNW_REG_IP, &target);
188    ms_exc->ExceptionCode = STATUS_GCC_UNWIND;
189#ifdef __x86_64__
190    ms_exc->ExceptionInformation[2] = disp->TargetIp;
191#elif defined(__arm__) || defined(__aarch64__)
192    ms_exc->ExceptionInformation[2] = disp->TargetPc;
193#endif
194    ms_exc->ExceptionInformation[3] = exc->private_[3];
195    // Give NTRTL some scratch space to keep track of the collided unwind.
196    // Don't use the one that was passed in; we don't want to overwrite the
197    // context in the DISPATCHER_CONTEXT.
198    CONTEXT new_ctx;
199    RtlUnwindEx(frame, (PVOID)target, ms_exc, (PVOID)retval, &new_ctx, disp->HistoryTable);
200    _LIBUNWIND_ABORT("RtlUnwindEx() failed");
201  }
202  // Anything else indicates a serious problem.
203  default: return ExceptionContinueExecution;
204  }
205}
206
207/// Personality function returned by \c __unw_get_proc_info() in SEH contexts.
208/// This is a wrapper that calls the real SEH handler function, which in
209/// turn (at least, for Itanium-style frames) calls the real Itanium
210/// personality function (see \c _GCC_specific_handler()).
211extern "C" _Unwind_Reason_Code
212__libunwind_seh_personality(int version, _Unwind_Action state,
213                            uint64_t klass, _Unwind_Exception *exc,
214                            struct _Unwind_Context *context) {
215  (void)version;
216  (void)klass;
217  EXCEPTION_RECORD ms_exc;
218  bool phase2 = (state & (_UA_SEARCH_PHASE|_UA_CLEANUP_PHASE)) == _UA_CLEANUP_PHASE;
219  ms_exc.ExceptionCode = STATUS_GCC_THROW;
220  ms_exc.ExceptionFlags = 0;
221  ms_exc.NumberParameters = 3;
222  ms_exc.ExceptionInformation[0] = (ULONG_PTR)exc;
223  ms_exc.ExceptionInformation[1] = (ULONG_PTR)context;
224  ms_exc.ExceptionInformation[2] = state;
225  DISPATCHER_CONTEXT *disp_ctx =
226      __unw_seh_get_disp_ctx((unw_cursor_t *)context);
227  EXCEPTION_DISPOSITION ms_act = disp_ctx->LanguageHandler(&ms_exc,
228                                                           (PVOID)disp_ctx->EstablisherFrame,
229                                                           disp_ctx->ContextRecord,
230                                                           disp_ctx);
231  switch (ms_act) {
232  case ExceptionContinueSearch: return _URC_CONTINUE_UNWIND;
233  case 4 /*ExceptionExecuteHandler*/:
234    return phase2 ? _URC_INSTALL_CONTEXT : _URC_HANDLER_FOUND;
235  default:
236    return phase2 ? _URC_FATAL_PHASE2_ERROR : _URC_FATAL_PHASE1_ERROR;
237  }
238}
239
240static _Unwind_Reason_Code
241unwind_phase2_forced(unw_context_t *uc,
242                     _Unwind_Exception *exception_object,
243                     _Unwind_Stop_Fn stop, void *stop_parameter) {
244  unw_cursor_t cursor2;
245  __unw_init_local(&cursor2, uc);
246
247  // Walk each frame until we reach where search phase said to stop
248  while (__unw_step(&cursor2) > 0) {
249
250    // Update info about this frame.
251    unw_proc_info_t frameInfo;
252    if (__unw_get_proc_info(&cursor2, &frameInfo) != UNW_ESUCCESS) {
253      _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): __unw_step "
254                                 "failed => _URC_END_OF_STACK",
255                                 (void *)exception_object);
256      return _URC_FATAL_PHASE2_ERROR;
257    }
258
259    // When tracing, print state information.
260    if (_LIBUNWIND_TRACING_UNWINDING) {
261      char functionBuf[512];
262      const char *functionName = functionBuf;
263      unw_word_t offset;
264      if ((__unw_get_proc_name(&cursor2, functionBuf, sizeof(functionBuf),
265                               &offset) != UNW_ESUCCESS) ||
266          (frameInfo.start_ip + offset > frameInfo.end_ip))
267        functionName = ".anonymous.";
268      _LIBUNWIND_TRACE_UNWINDING(
269          "unwind_phase2_forced(ex_ojb=%p): start_ip=0x%" PRIx64
270          ", func=%s, lsda=0x%" PRIx64 ", personality=0x%" PRIx64,
271          (void *)exception_object, frameInfo.start_ip, functionName,
272          frameInfo.lsda, frameInfo.handler);
273    }
274
275    // Call stop function at each frame.
276    _Unwind_Action action =
277        (_Unwind_Action)(_UA_FORCE_UNWIND | _UA_CLEANUP_PHASE);
278    _Unwind_Reason_Code stopResult =
279        (*stop)(1, action, exception_object->exception_class, exception_object,
280                (struct _Unwind_Context *)(&cursor2), stop_parameter);
281    _LIBUNWIND_TRACE_UNWINDING(
282        "unwind_phase2_forced(ex_ojb=%p): stop function returned %d",
283        (void *)exception_object, stopResult);
284    if (stopResult != _URC_NO_REASON) {
285      _LIBUNWIND_TRACE_UNWINDING(
286          "unwind_phase2_forced(ex_ojb=%p): stopped by stop function",
287          (void *)exception_object);
288      return _URC_FATAL_PHASE2_ERROR;
289    }
290
291    // If there is a personality routine, tell it we are unwinding.
292    if (frameInfo.handler != 0) {
293      __personality_routine p =
294          (__personality_routine)(intptr_t)(frameInfo.handler);
295      _LIBUNWIND_TRACE_UNWINDING(
296          "unwind_phase2_forced(ex_ojb=%p): calling personality function %p",
297          (void *)exception_object, (void *)(uintptr_t)p);
298      _Unwind_Reason_Code personalityResult =
299          (*p)(1, action, exception_object->exception_class, exception_object,
300               (struct _Unwind_Context *)(&cursor2));
301      switch (personalityResult) {
302      case _URC_CONTINUE_UNWIND:
303        _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
304                                   "personality returned "
305                                   "_URC_CONTINUE_UNWIND",
306                                   (void *)exception_object);
307        // Destructors called, continue unwinding
308        break;
309      case _URC_INSTALL_CONTEXT:
310        _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
311                                   "personality returned "
312                                   "_URC_INSTALL_CONTEXT",
313                                   (void *)exception_object);
314        // We may get control back if landing pad calls _Unwind_Resume().
315        __unw_resume(&cursor2);
316        break;
317      default:
318        // Personality routine returned an unknown result code.
319        _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
320                                   "personality returned %d, "
321                                   "_URC_FATAL_PHASE2_ERROR",
322                                   (void *)exception_object, personalityResult);
323        return _URC_FATAL_PHASE2_ERROR;
324      }
325    }
326  }
327
328  // Call stop function one last time and tell it we've reached the end
329  // of the stack.
330  _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): calling stop "
331                             "function with _UA_END_OF_STACK",
332                             (void *)exception_object);
333  _Unwind_Action lastAction =
334      (_Unwind_Action)(_UA_FORCE_UNWIND | _UA_CLEANUP_PHASE | _UA_END_OF_STACK);
335  (*stop)(1, lastAction, exception_object->exception_class, exception_object,
336          (struct _Unwind_Context *)(&cursor2), stop_parameter);
337
338  // Clean up phase did not resume at the frame that the search phase said it
339  // would.
340  return _URC_FATAL_PHASE2_ERROR;
341}
342
343/// Called by \c __cxa_throw().  Only returns if there is a fatal error.
344_LIBUNWIND_EXPORT _Unwind_Reason_Code
345_Unwind_RaiseException(_Unwind_Exception *exception_object) {
346  _LIBUNWIND_TRACE_API("_Unwind_RaiseException(ex_obj=%p)",
347                       (void *)exception_object);
348
349  // Mark that this is a non-forced unwind, so _Unwind_Resume()
350  // can do the right thing.
351  memset(exception_object->private_, 0, sizeof(exception_object->private_));
352
353  // phase 1: the search phase
354  // We'll let the system do that for us.
355  RaiseException(STATUS_GCC_THROW, 0, 1, (ULONG_PTR *)&exception_object);
356
357  // If we get here, either something went horribly wrong or we reached the
358  // top of the stack. Either way, let libc++abi call std::terminate().
359  return _URC_END_OF_STACK;
360}
361
362/// When \c _Unwind_RaiseException() is in phase2, it hands control
363/// to the personality function at each frame.  The personality
364/// may force a jump to a landing pad in that function; the landing
365/// pad code may then call \c _Unwind_Resume() to continue with the
366/// unwinding.  Note: the call to \c _Unwind_Resume() is from compiler
367/// geneated user code.  All other \c _Unwind_* routines are called
368/// by the C++ runtime \c __cxa_* routines.
369///
370/// Note: re-throwing an exception (as opposed to continuing the unwind)
371/// is implemented by having the code call \c __cxa_rethrow() which
372/// in turn calls \c _Unwind_Resume_or_Rethrow().
373_LIBUNWIND_EXPORT void
374_Unwind_Resume(_Unwind_Exception *exception_object) {
375  _LIBUNWIND_TRACE_API("_Unwind_Resume(ex_obj=%p)", (void *)exception_object);
376
377  if (exception_object->private_[0] != 0) {
378    unw_context_t uc;
379
380    __unw_getcontext(&uc);
381    unwind_phase2_forced(&uc, exception_object,
382                         (_Unwind_Stop_Fn) exception_object->private_[0],
383                         (void *)exception_object->private_[4]);
384  } else {
385    // Recover the parameters for the unwind from the exception object
386    // so we can start unwinding again.
387    EXCEPTION_RECORD ms_exc;
388    CONTEXT ms_ctx;
389    UNWIND_HISTORY_TABLE hist;
390
391    memset(&ms_exc, 0, sizeof(ms_exc));
392    memset(&hist, 0, sizeof(hist));
393    ms_exc.ExceptionCode = STATUS_GCC_THROW;
394    ms_exc.ExceptionFlags = EXCEPTION_NONCONTINUABLE;
395    ms_exc.NumberParameters = 4;
396    ms_exc.ExceptionInformation[0] = (ULONG_PTR)exception_object;
397    ms_exc.ExceptionInformation[1] = exception_object->private_[1];
398    ms_exc.ExceptionInformation[2] = exception_object->private_[2];
399    ms_exc.ExceptionInformation[3] = exception_object->private_[3];
400    RtlUnwindEx((PVOID)exception_object->private_[1],
401                (PVOID)exception_object->private_[2], &ms_exc,
402                exception_object, &ms_ctx, &hist);
403  }
404
405  // Clients assume _Unwind_Resume() does not return, so all we can do is abort.
406  _LIBUNWIND_ABORT("_Unwind_Resume() can't return");
407}
408
409/// Not used by C++.
410/// Unwinds stack, calling "stop" function at each frame.
411/// Could be used to implement \c longjmp().
412_LIBUNWIND_EXPORT _Unwind_Reason_Code
413_Unwind_ForcedUnwind(_Unwind_Exception *exception_object,
414                     _Unwind_Stop_Fn stop, void *stop_parameter) {
415  _LIBUNWIND_TRACE_API("_Unwind_ForcedUnwind(ex_obj=%p, stop=%p)",
416                       (void *)exception_object, (void *)(uintptr_t)stop);
417  unw_context_t uc;
418  __unw_getcontext(&uc);
419
420  // Mark that this is a forced unwind, so _Unwind_Resume() can do
421  // the right thing.
422  exception_object->private_[0] = (uintptr_t) stop;
423  exception_object->private_[4] = (uintptr_t) stop_parameter;
424
425  // do it
426  return unwind_phase2_forced(&uc, exception_object, stop, stop_parameter);
427}
428
429/// Called by personality handler during phase 2 to get LSDA for current frame.
430_LIBUNWIND_EXPORT uintptr_t
431_Unwind_GetLanguageSpecificData(struct _Unwind_Context *context) {
432  uintptr_t result =
433      (uintptr_t)__unw_seh_get_disp_ctx((unw_cursor_t *)context)->HandlerData;
434  _LIBUNWIND_TRACE_API(
435      "_Unwind_GetLanguageSpecificData(context=%p) => 0x%" PRIxPTR,
436      (void *)context, result);
437  return result;
438}
439
440/// Called by personality handler during phase 2 to find the start of the
441/// function.
442_LIBUNWIND_EXPORT uintptr_t
443_Unwind_GetRegionStart(struct _Unwind_Context *context) {
444  DISPATCHER_CONTEXT *disp = __unw_seh_get_disp_ctx((unw_cursor_t *)context);
445  uintptr_t result = (uintptr_t)disp->FunctionEntry->BeginAddress + disp->ImageBase;
446  _LIBUNWIND_TRACE_API("_Unwind_GetRegionStart(context=%p) => 0x%" PRIxPTR,
447                       (void *)context, result);
448  return result;
449}
450
451static int __unw_init_seh(unw_cursor_t *cursor, CONTEXT *context) {
452#ifdef _LIBUNWIND_TARGET_X86_64
453  new (reinterpret_cast<UnwindCursor<LocalAddressSpace, Registers_x86_64> *>(cursor))
454      UnwindCursor<LocalAddressSpace, Registers_x86_64>(
455          context, LocalAddressSpace::sThisAddressSpace);
456  auto *co = reinterpret_cast<AbstractUnwindCursor *>(cursor);
457  co->setInfoBasedOnIPRegister();
458  return UNW_ESUCCESS;
459#elif defined(_LIBUNWIND_TARGET_ARM)
460  new (reinterpret_cast<UnwindCursor<LocalAddressSpace, Registers_arm> *>(cursor))
461      UnwindCursor<LocalAddressSpace, Registers_arm>(
462          context, LocalAddressSpace::sThisAddressSpace);
463  auto *co = reinterpret_cast<AbstractUnwindCursor *>(cursor);
464  co->setInfoBasedOnIPRegister();
465  return UNW_ESUCCESS;
466#elif defined(_LIBUNWIND_TARGET_AARCH64)
467  new (reinterpret_cast<UnwindCursor<LocalAddressSpace, Registers_arm64> *>(cursor))
468      UnwindCursor<LocalAddressSpace, Registers_arm64>(
469          context, LocalAddressSpace::sThisAddressSpace);
470  auto *co = reinterpret_cast<AbstractUnwindCursor *>(cursor);
471  co->setInfoBasedOnIPRegister();
472  return UNW_ESUCCESS;
473#else
474  return UNW_EINVAL;
475#endif
476}
477
478static DISPATCHER_CONTEXT *__unw_seh_get_disp_ctx(unw_cursor_t *cursor) {
479#ifdef _LIBUNWIND_TARGET_X86_64
480  return reinterpret_cast<UnwindCursor<LocalAddressSpace, Registers_x86_64> *>(cursor)->getDispatcherContext();
481#elif defined(_LIBUNWIND_TARGET_ARM)
482  return reinterpret_cast<UnwindCursor<LocalAddressSpace, Registers_arm> *>(cursor)->getDispatcherContext();
483#elif defined(_LIBUNWIND_TARGET_AARCH64)
484  return reinterpret_cast<UnwindCursor<LocalAddressSpace, Registers_arm64> *>(cursor)->getDispatcherContext();
485#else
486  return nullptr;
487#endif
488}
489
490static void __unw_seh_set_disp_ctx(unw_cursor_t *cursor,
491                                   DISPATCHER_CONTEXT *disp) {
492#ifdef _LIBUNWIND_TARGET_X86_64
493  reinterpret_cast<UnwindCursor<LocalAddressSpace, Registers_x86_64> *>(cursor)->setDispatcherContext(disp);
494#elif defined(_LIBUNWIND_TARGET_ARM)
495  reinterpret_cast<UnwindCursor<LocalAddressSpace, Registers_arm> *>(cursor)->setDispatcherContext(disp);
496#elif defined(_LIBUNWIND_TARGET_AARCH64)
497  reinterpret_cast<UnwindCursor<LocalAddressSpace, Registers_arm64> *>(cursor)->setDispatcherContext(disp);
498#endif
499}
500
501#endif // defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
502