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1 //===------------------------- UnwindLevel1.c -----------------------------===//
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 // Implements C++ ABI Exception Handling Level 1 as documented at:
9 //      https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html
10 // using libunwind
11 //
12 //===----------------------------------------------------------------------===//
13 
14 // ARM EHABI does not specify _Unwind_{Get,Set}{GR,IP}().  Thus, we are
15 // defining inline functions to delegate the function calls to
16 // _Unwind_VRS_{Get,Set}().  However, some applications might declare the
17 // function protetype directly (instead of including <unwind.h>), thus we need
18 // to export these functions from libunwind.so as well.
19 #define _LIBUNWIND_UNWIND_LEVEL1_EXTERNAL_LINKAGE 1
20 
21 #include <inttypes.h>
22 #include <stdint.h>
23 #include <stdbool.h>
24 #include <stdlib.h>
25 #include <stdio.h>
26 #include <string.h>
27 
28 #include "config.h"
29 #include "libunwind.h"
30 #include "libunwind_ext.h"
31 #include "unwind.h"
32 
33 #if !defined(_LIBUNWIND_ARM_EHABI) && !defined(__USING_SJLJ_EXCEPTIONS__)
34 
35 #ifndef _LIBUNWIND_SUPPORT_SEH_UNWIND
36 
37 static _Unwind_Reason_Code
unwind_phase1(unw_context_t * uc,unw_cursor_t * cursor,_Unwind_Exception * exception_object)38 unwind_phase1(unw_context_t *uc, unw_cursor_t *cursor, _Unwind_Exception *exception_object) {
39   __unw_init_local(cursor, uc);
40 
41   // Walk each frame looking for a place to stop.
42   while (true) {
43     // Ask libunwind to get next frame (skip over first which is
44     // _Unwind_RaiseException).
45     int stepResult = __unw_step(cursor);
46     if (stepResult == 0) {
47       _LIBUNWIND_TRACE_UNWINDING(
48           "unwind_phase1(ex_ojb=%p): __unw_step() reached "
49           "bottom => _URC_END_OF_STACK",
50           (void *)exception_object);
51       return _URC_END_OF_STACK;
52     } else if (stepResult < 0) {
53       _LIBUNWIND_TRACE_UNWINDING(
54           "unwind_phase1(ex_ojb=%p): __unw_step failed => "
55           "_URC_FATAL_PHASE1_ERROR",
56           (void *)exception_object);
57       return _URC_FATAL_PHASE1_ERROR;
58     }
59 
60     // See if frame has code to run (has personality routine).
61     unw_proc_info_t frameInfo;
62     unw_word_t sp;
63     if (__unw_get_proc_info(cursor, &frameInfo) != UNW_ESUCCESS) {
64       _LIBUNWIND_TRACE_UNWINDING(
65           "unwind_phase1(ex_ojb=%p): __unw_get_proc_info "
66           "failed => _URC_FATAL_PHASE1_ERROR",
67           (void *)exception_object);
68       return _URC_FATAL_PHASE1_ERROR;
69     }
70 
71     // When tracing, print state information.
72     if (_LIBUNWIND_TRACING_UNWINDING) {
73       char functionBuf[512];
74       const char *functionName = functionBuf;
75       unw_word_t offset;
76       if ((__unw_get_proc_name(cursor, functionBuf, sizeof(functionBuf),
77                                &offset) != UNW_ESUCCESS) ||
78           (frameInfo.start_ip + offset > frameInfo.end_ip))
79         functionName = ".anonymous.";
80       unw_word_t pc;
81       __unw_get_reg(cursor, UNW_REG_IP, &pc);
82       _LIBUNWIND_TRACE_UNWINDING(
83           "unwind_phase1(ex_ojb=%p): pc=0x%" PRIxPTR ", start_ip=0x%" PRIxPTR
84           ", func=%s, lsda=0x%" PRIxPTR ", personality=0x%" PRIxPTR "",
85           (void *)exception_object, pc, frameInfo.start_ip, functionName,
86           frameInfo.lsda, frameInfo.handler);
87     }
88 
89     // If there is a personality routine, ask it if it will want to stop at
90     // this frame.
91     if (frameInfo.handler != 0) {
92       _Unwind_Personality_Fn p =
93           (_Unwind_Personality_Fn)(uintptr_t)(frameInfo.handler);
94       _LIBUNWIND_TRACE_UNWINDING(
95           "unwind_phase1(ex_ojb=%p): calling personality function %p",
96           (void *)exception_object, (void *)(uintptr_t)p);
97       _Unwind_Reason_Code personalityResult =
98           (*p)(1, _UA_SEARCH_PHASE, exception_object->exception_class,
99                exception_object, (struct _Unwind_Context *)(cursor));
100       switch (personalityResult) {
101       case _URC_HANDLER_FOUND:
102         // found a catch clause or locals that need destructing in this frame
103         // stop search and remember stack pointer at the frame
104         __unw_get_reg(cursor, UNW_REG_SP, &sp);
105         exception_object->private_2 = (uintptr_t)sp;
106         _LIBUNWIND_TRACE_UNWINDING(
107             "unwind_phase1(ex_ojb=%p): _URC_HANDLER_FOUND",
108             (void *)exception_object);
109         return _URC_NO_REASON;
110 
111       case _URC_CONTINUE_UNWIND:
112         _LIBUNWIND_TRACE_UNWINDING(
113             "unwind_phase1(ex_ojb=%p): _URC_CONTINUE_UNWIND",
114             (void *)exception_object);
115         // continue unwinding
116         break;
117 
118       default:
119         // something went wrong
120         _LIBUNWIND_TRACE_UNWINDING(
121             "unwind_phase1(ex_ojb=%p): _URC_FATAL_PHASE1_ERROR",
122             (void *)exception_object);
123         return _URC_FATAL_PHASE1_ERROR;
124       }
125     }
126   }
127   return _URC_NO_REASON;
128 }
129 
130 
131 static _Unwind_Reason_Code
unwind_phase2(unw_context_t * uc,unw_cursor_t * cursor,_Unwind_Exception * exception_object)132 unwind_phase2(unw_context_t *uc, unw_cursor_t *cursor, _Unwind_Exception *exception_object) {
133   __unw_init_local(cursor, uc);
134 
135   _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p)",
136                              (void *)exception_object);
137 
138   // Walk each frame until we reach where search phase said to stop.
139   while (true) {
140 
141     // Ask libunwind to get next frame (skip over first which is
142     // _Unwind_RaiseException).
143     int stepResult = __unw_step(cursor);
144     if (stepResult == 0) {
145       _LIBUNWIND_TRACE_UNWINDING(
146           "unwind_phase2(ex_ojb=%p): __unw_step() reached "
147           "bottom => _URC_END_OF_STACK",
148           (void *)exception_object);
149       return _URC_END_OF_STACK;
150     } else if (stepResult < 0) {
151       _LIBUNWIND_TRACE_UNWINDING(
152           "unwind_phase2(ex_ojb=%p): __unw_step failed => "
153           "_URC_FATAL_PHASE1_ERROR",
154           (void *)exception_object);
155       return _URC_FATAL_PHASE2_ERROR;
156     }
157 
158     // Get info about this frame.
159     unw_word_t sp;
160     unw_proc_info_t frameInfo;
161     __unw_get_reg(cursor, UNW_REG_SP, &sp);
162     if (__unw_get_proc_info(cursor, &frameInfo) != UNW_ESUCCESS) {
163       _LIBUNWIND_TRACE_UNWINDING(
164           "unwind_phase2(ex_ojb=%p): __unw_get_proc_info "
165           "failed => _URC_FATAL_PHASE1_ERROR",
166           (void *)exception_object);
167       return _URC_FATAL_PHASE2_ERROR;
168     }
169 
170     // When tracing, print state information.
171     if (_LIBUNWIND_TRACING_UNWINDING) {
172       char functionBuf[512];
173       const char *functionName = functionBuf;
174       unw_word_t offset;
175       if ((__unw_get_proc_name(cursor, functionBuf, sizeof(functionBuf),
176                                &offset) != UNW_ESUCCESS) ||
177           (frameInfo.start_ip + offset > frameInfo.end_ip))
178         functionName = ".anonymous.";
179       _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): start_ip=0x%" PRIxPTR
180                                  ", func=%s, sp=0x%" PRIxPTR ", lsda=0x%" PRIxPTR
181                                  ", personality=0x%" PRIxPTR,
182                                  (void *)exception_object, frameInfo.start_ip,
183                                  functionName, sp, frameInfo.lsda,
184                                  frameInfo.handler);
185     }
186 
187     // If there is a personality routine, tell it we are unwinding.
188     if (frameInfo.handler != 0) {
189       _Unwind_Personality_Fn p =
190           (_Unwind_Personality_Fn)(uintptr_t)(frameInfo.handler);
191       _Unwind_Action action = _UA_CLEANUP_PHASE;
192       if (sp == exception_object->private_2) {
193         // Tell personality this was the frame it marked in phase 1.
194         action = (_Unwind_Action)(_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME);
195       }
196        _Unwind_Reason_Code personalityResult =
197           (*p)(1, action, exception_object->exception_class, exception_object,
198                (struct _Unwind_Context *)(cursor));
199       switch (personalityResult) {
200       case _URC_CONTINUE_UNWIND:
201         // Continue unwinding
202         _LIBUNWIND_TRACE_UNWINDING(
203             "unwind_phase2(ex_ojb=%p): _URC_CONTINUE_UNWIND",
204             (void *)exception_object);
205         if (sp == exception_object->private_2) {
206           // Phase 1 said we would stop at this frame, but we did not...
207           _LIBUNWIND_ABORT("during phase1 personality function said it would "
208                            "stop here, but now in phase2 it did not stop here");
209         }
210         break;
211       case _URC_INSTALL_CONTEXT:
212         _LIBUNWIND_TRACE_UNWINDING(
213             "unwind_phase2(ex_ojb=%p): _URC_INSTALL_CONTEXT",
214             (void *)exception_object);
215         // Personality routine says to transfer control to landing pad.
216         // We may get control back if landing pad calls _Unwind_Resume().
217         if (_LIBUNWIND_TRACING_UNWINDING) {
218           unw_word_t pc;
219           __unw_get_reg(cursor, UNW_REG_IP, &pc);
220           __unw_get_reg(cursor, UNW_REG_SP, &sp);
221           _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): re-entering "
222                                      "user code with ip=0x%" PRIxPTR
223                                      ", sp=0x%" PRIxPTR,
224                                      (void *)exception_object, pc, sp);
225         }
226         __unw_resume(cursor);
227         // __unw_resume() only returns if there was an error.
228         return _URC_FATAL_PHASE2_ERROR;
229       default:
230         // Personality routine returned an unknown result code.
231         _LIBUNWIND_DEBUG_LOG("personality function returned unknown result %d",
232                              personalityResult);
233         return _URC_FATAL_PHASE2_ERROR;
234       }
235     }
236   }
237 
238   // Clean up phase did not resume at the frame that the search phase
239   // said it would...
240   return _URC_FATAL_PHASE2_ERROR;
241 }
242 
243 static _Unwind_Reason_Code
unwind_phase2_forced(unw_context_t * uc,unw_cursor_t * cursor,_Unwind_Exception * exception_object,_Unwind_Stop_Fn stop,void * stop_parameter)244 unwind_phase2_forced(unw_context_t *uc, unw_cursor_t *cursor,
245                      _Unwind_Exception *exception_object,
246                      _Unwind_Stop_Fn stop, void *stop_parameter) {
247   __unw_init_local(cursor, uc);
248 
249   // Walk each frame until we reach where search phase said to stop
250   while (__unw_step(cursor) > 0) {
251 
252     // Update info about this frame.
253     unw_proc_info_t frameInfo;
254     if (__unw_get_proc_info(cursor, &frameInfo) != UNW_ESUCCESS) {
255       _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): __unw_step "
256                                  "failed => _URC_END_OF_STACK",
257                                  (void *)exception_object);
258       return _URC_FATAL_PHASE2_ERROR;
259     }
260 
261     // When tracing, print state information.
262     if (_LIBUNWIND_TRACING_UNWINDING) {
263       char functionBuf[512];
264       const char *functionName = functionBuf;
265       unw_word_t offset;
266       if ((__unw_get_proc_name(cursor, functionBuf, sizeof(functionBuf),
267                                &offset) != UNW_ESUCCESS) ||
268           (frameInfo.start_ip + offset > frameInfo.end_ip))
269         functionName = ".anonymous.";
270       _LIBUNWIND_TRACE_UNWINDING(
271           "unwind_phase2_forced(ex_ojb=%p): start_ip=0x%" PRIxPTR
272           ", func=%s, lsda=0x%" PRIxPTR ", personality=0x%" PRIxPTR,
273           (void *)exception_object, frameInfo.start_ip, functionName,
274           frameInfo.lsda, frameInfo.handler);
275     }
276 
277     // Call stop function at each frame.
278     _Unwind_Action action =
279         (_Unwind_Action)(_UA_FORCE_UNWIND | _UA_CLEANUP_PHASE);
280     _Unwind_Reason_Code stopResult =
281         (*stop)(1, action, exception_object->exception_class, exception_object,
282                 (struct _Unwind_Context *)(cursor), stop_parameter);
283     _LIBUNWIND_TRACE_UNWINDING(
284         "unwind_phase2_forced(ex_ojb=%p): stop function returned %d",
285         (void *)exception_object, stopResult);
286     if (stopResult != _URC_NO_REASON) {
287       _LIBUNWIND_TRACE_UNWINDING(
288           "unwind_phase2_forced(ex_ojb=%p): stopped by stop function",
289           (void *)exception_object);
290       return _URC_FATAL_PHASE2_ERROR;
291     }
292 
293     // If there is a personality routine, tell it we are unwinding.
294     if (frameInfo.handler != 0) {
295       _Unwind_Personality_Fn p =
296           (_Unwind_Personality_Fn)(intptr_t)(frameInfo.handler);
297       _LIBUNWIND_TRACE_UNWINDING(
298           "unwind_phase2_forced(ex_ojb=%p): calling personality function %p",
299           (void *)exception_object, (void *)(uintptr_t)p);
300       _Unwind_Reason_Code personalityResult =
301           (*p)(1, action, exception_object->exception_class, exception_object,
302                (struct _Unwind_Context *)(cursor));
303       switch (personalityResult) {
304       case _URC_CONTINUE_UNWIND:
305         _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
306                                    "personality returned "
307                                    "_URC_CONTINUE_UNWIND",
308                                    (void *)exception_object);
309         // Destructors called, continue unwinding
310         break;
311       case _URC_INSTALL_CONTEXT:
312         _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
313                                    "personality returned "
314                                    "_URC_INSTALL_CONTEXT",
315                                    (void *)exception_object);
316         // We may get control back if landing pad calls _Unwind_Resume().
317         __unw_resume(cursor);
318         break;
319       default:
320         // Personality routine returned an unknown result code.
321         _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
322                                    "personality returned %d, "
323                                    "_URC_FATAL_PHASE2_ERROR",
324                                    (void *)exception_object, personalityResult);
325         return _URC_FATAL_PHASE2_ERROR;
326       }
327     }
328   }
329 
330   // Call stop function one last time and tell it we've reached the end
331   // of the stack.
332   _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): calling stop "
333                              "function with _UA_END_OF_STACK",
334                              (void *)exception_object);
335   _Unwind_Action lastAction =
336       (_Unwind_Action)(_UA_FORCE_UNWIND | _UA_CLEANUP_PHASE | _UA_END_OF_STACK);
337   (*stop)(1, lastAction, exception_object->exception_class, exception_object,
338           (struct _Unwind_Context *)(cursor), stop_parameter);
339 
340   // Clean up phase did not resume at the frame that the search phase said it
341   // would.
342   return _URC_FATAL_PHASE2_ERROR;
343 }
344 
345 
346 /// Called by __cxa_throw.  Only returns if there is a fatal error.
347 _LIBUNWIND_EXPORT _Unwind_Reason_Code
_Unwind_RaiseException(_Unwind_Exception * exception_object)348 _Unwind_RaiseException(_Unwind_Exception *exception_object) {
349   _LIBUNWIND_TRACE_API("_Unwind_RaiseException(ex_obj=%p)",
350                        (void *)exception_object);
351   unw_context_t uc;
352   unw_cursor_t cursor;
353   __unw_getcontext(&uc);
354 
355   // Mark that this is a non-forced unwind, so _Unwind_Resume()
356   // can do the right thing.
357   exception_object->private_1 = 0;
358   exception_object->private_2 = 0;
359 
360   // phase 1: the search phase
361   _Unwind_Reason_Code phase1 = unwind_phase1(&uc, &cursor, exception_object);
362   if (phase1 != _URC_NO_REASON)
363     return phase1;
364 
365   // phase 2: the clean up phase
366   return unwind_phase2(&uc, &cursor, exception_object);
367 }
368 
369 
370 
371 /// When _Unwind_RaiseException() is in phase2, it hands control
372 /// to the personality function at each frame.  The personality
373 /// may force a jump to a landing pad in that function, the landing
374 /// pad code may then call _Unwind_Resume() to continue with the
375 /// unwinding.  Note: the call to _Unwind_Resume() is from compiler
376 /// geneated user code.  All other _Unwind_* routines are called
377 /// by the C++ runtime __cxa_* routines.
378 ///
379 /// Note: re-throwing an exception (as opposed to continuing the unwind)
380 /// is implemented by having the code call __cxa_rethrow() which
381 /// in turn calls _Unwind_Resume_or_Rethrow().
382 _LIBUNWIND_EXPORT void
_Unwind_Resume(_Unwind_Exception * exception_object)383 _Unwind_Resume(_Unwind_Exception *exception_object) {
384   _LIBUNWIND_TRACE_API("_Unwind_Resume(ex_obj=%p)", (void *)exception_object);
385   unw_context_t uc;
386   unw_cursor_t cursor;
387   __unw_getcontext(&uc);
388 
389   if (exception_object->private_1 != 0)
390     unwind_phase2_forced(&uc, &cursor, exception_object,
391                          (_Unwind_Stop_Fn) exception_object->private_1,
392                          (void *)exception_object->private_2);
393   else
394     unwind_phase2(&uc, &cursor, exception_object);
395 
396   // Clients assume _Unwind_Resume() does not return, so all we can do is abort.
397   _LIBUNWIND_ABORT("_Unwind_Resume() can't return");
398 }
399 
400 
401 
402 /// Not used by C++.
403 /// Unwinds stack, calling "stop" function at each frame.
404 /// Could be used to implement longjmp().
405 _LIBUNWIND_EXPORT _Unwind_Reason_Code
_Unwind_ForcedUnwind(_Unwind_Exception * exception_object,_Unwind_Stop_Fn stop,void * stop_parameter)406 _Unwind_ForcedUnwind(_Unwind_Exception *exception_object,
407                      _Unwind_Stop_Fn stop, void *stop_parameter) {
408   _LIBUNWIND_TRACE_API("_Unwind_ForcedUnwind(ex_obj=%p, stop=%p)",
409                        (void *)exception_object, (void *)(uintptr_t)stop);
410   unw_context_t uc;
411   unw_cursor_t cursor;
412   __unw_getcontext(&uc);
413 
414   // Mark that this is a forced unwind, so _Unwind_Resume() can do
415   // the right thing.
416   exception_object->private_1 = (uintptr_t) stop;
417   exception_object->private_2 = (uintptr_t) stop_parameter;
418 
419   // do it
420   return unwind_phase2_forced(&uc, &cursor, exception_object, stop, stop_parameter);
421 }
422 
423 
424 /// Called by personality handler during phase 2 to get LSDA for current frame.
425 _LIBUNWIND_EXPORT uintptr_t
_Unwind_GetLanguageSpecificData(struct _Unwind_Context * context)426 _Unwind_GetLanguageSpecificData(struct _Unwind_Context *context) {
427   unw_cursor_t *cursor = (unw_cursor_t *)context;
428   unw_proc_info_t frameInfo;
429   uintptr_t result = 0;
430   if (__unw_get_proc_info(cursor, &frameInfo) == UNW_ESUCCESS)
431     result = (uintptr_t)frameInfo.lsda;
432   _LIBUNWIND_TRACE_API(
433       "_Unwind_GetLanguageSpecificData(context=%p) => 0x%" PRIxPTR,
434       (void *)context, result);
435   if (result != 0) {
436     if (*((uint8_t *)result) != 0xFF)
437       _LIBUNWIND_DEBUG_LOG("lsda at 0x%" PRIxPTR " does not start with 0xFF",
438                            result);
439   }
440   return result;
441 }
442 
443 
444 /// Called by personality handler during phase 2 to find the start of the
445 /// function.
446 _LIBUNWIND_EXPORT uintptr_t
_Unwind_GetRegionStart(struct _Unwind_Context * context)447 _Unwind_GetRegionStart(struct _Unwind_Context *context) {
448   unw_cursor_t *cursor = (unw_cursor_t *)context;
449   unw_proc_info_t frameInfo;
450   uintptr_t result = 0;
451   if (__unw_get_proc_info(cursor, &frameInfo) == UNW_ESUCCESS)
452     result = (uintptr_t)frameInfo.start_ip;
453   _LIBUNWIND_TRACE_API("_Unwind_GetRegionStart(context=%p) => 0x%" PRIxPTR,
454                        (void *)context, result);
455   return result;
456 }
457 
458 #endif // !_LIBUNWIND_SUPPORT_SEH_UNWIND
459 
460 /// Called by personality handler during phase 2 if a foreign exception
461 // is caught.
462 _LIBUNWIND_EXPORT void
_Unwind_DeleteException(_Unwind_Exception * exception_object)463 _Unwind_DeleteException(_Unwind_Exception *exception_object) {
464   _LIBUNWIND_TRACE_API("_Unwind_DeleteException(ex_obj=%p)",
465                        (void *)exception_object);
466   if (exception_object->exception_cleanup != NULL)
467     (*exception_object->exception_cleanup)(_URC_FOREIGN_EXCEPTION_CAUGHT,
468                                            exception_object);
469 }
470 
471 /// Called by personality handler during phase 2 to get register values.
472 _LIBUNWIND_EXPORT uintptr_t
_Unwind_GetGR(struct _Unwind_Context * context,int index)473 _Unwind_GetGR(struct _Unwind_Context *context, int index) {
474   unw_cursor_t *cursor = (unw_cursor_t *)context;
475   unw_word_t result;
476   __unw_get_reg(cursor, index, &result);
477   _LIBUNWIND_TRACE_API("_Unwind_GetGR(context=%p, reg=%d) => 0x%" PRIxPTR,
478                        (void *)context, index, result);
479   return (uintptr_t)result;
480 }
481 
482 /// Called by personality handler during phase 2 to alter register values.
_Unwind_SetGR(struct _Unwind_Context * context,int index,uintptr_t value)483 _LIBUNWIND_EXPORT void _Unwind_SetGR(struct _Unwind_Context *context, int index,
484                                      uintptr_t value) {
485   _LIBUNWIND_TRACE_API("_Unwind_SetGR(context=%p, reg=%d, value=0x%0" PRIxPTR
486                        ")",
487                        (void *)context, index, value);
488   unw_cursor_t *cursor = (unw_cursor_t *)context;
489   __unw_set_reg(cursor, index, value);
490 }
491 
492 /// Called by personality handler during phase 2 to get instruction pointer.
_Unwind_GetIP(struct _Unwind_Context * context)493 _LIBUNWIND_EXPORT uintptr_t _Unwind_GetIP(struct _Unwind_Context *context) {
494   unw_cursor_t *cursor = (unw_cursor_t *)context;
495   unw_word_t result;
496   __unw_get_reg(cursor, UNW_REG_IP, &result);
497   _LIBUNWIND_TRACE_API("_Unwind_GetIP(context=%p) => 0x%" PRIxPTR,
498                        (void *)context, result);
499   return (uintptr_t)result;
500 }
501 
502 /// Called by personality handler during phase 2 to alter instruction pointer,
503 /// such as setting where the landing pad is, so _Unwind_Resume() will
504 /// start executing in the landing pad.
_Unwind_SetIP(struct _Unwind_Context * context,uintptr_t value)505 _LIBUNWIND_EXPORT void _Unwind_SetIP(struct _Unwind_Context *context,
506                                      uintptr_t value) {
507   _LIBUNWIND_TRACE_API("_Unwind_SetIP(context=%p, value=0x%0" PRIxPTR ")",
508                        (void *)context, value);
509   unw_cursor_t *cursor = (unw_cursor_t *)context;
510   __unw_set_reg(cursor, UNW_REG_IP, value);
511 }
512 
513 #endif // !defined(_LIBUNWIND_ARM_EHABI) && !defined(__USING_SJLJ_EXCEPTIONS__)
514