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// http://mentorembedded.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
37static _Unwind_Reason_Code
38unwind_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 bool handlerNotFound = true;
43 while (handlerNotFound) {
44 // Ask libunwind to get next frame (skip over first which is
45 // _Unwind_RaiseException).
46 int stepResult = __unw_step(cursor);
47 if (stepResult == 0) {
48 _LIBUNWIND_TRACE_UNWINDING(
49 "unwind_phase1(ex_ojb=%p): __unw_step() reached "
50 "bottom => _URC_END_OF_STACK",
51 (void *)exception_object);
52 return _URC_END_OF_STACK;
53 } else if (stepResult < 0) {
54 _LIBUNWIND_TRACE_UNWINDING(
55 "unwind_phase1(ex_ojb=%p): __unw_step failed => "
56 "_URC_FATAL_PHASE1_ERROR",
57 (void *)exception_object);
58 return _URC_FATAL_PHASE1_ERROR;
59 }
60
61 // See if frame has code to run (has personality routine).
62 unw_proc_info_t frameInfo;
63 unw_word_t sp;
64 if (__unw_get_proc_info(cursor, &frameInfo) != UNW_ESUCCESS) {
65 _LIBUNWIND_TRACE_UNWINDING(
66 "unwind_phase1(ex_ojb=%p): __unw_get_proc_info "
67 "failed => _URC_FATAL_PHASE1_ERROR",
68 (void *)exception_object);
69 return _URC_FATAL_PHASE1_ERROR;
70 }
71
72 // When tracing, print state information.
73 if (_LIBUNWIND_TRACING_UNWINDING) {
74 char functionBuf[512];
75 const char *functionName = functionBuf;
76 unw_word_t offset;
77 if ((__unw_get_proc_name(cursor, functionBuf, sizeof(functionBuf),
78 &offset) != UNW_ESUCCESS) ||
79 (frameInfo.start_ip + offset > frameInfo.end_ip))
80 functionName = ".anonymous.";
81 unw_word_t pc;
82 __unw_get_reg(cursor, UNW_REG_IP, &pc);
83 _LIBUNWIND_TRACE_UNWINDING(
84 "unwind_phase1(ex_ojb=%p): pc=0x%" PRIxPTR ", start_ip=0x%" PRIxPTR
85 ", func=%s, lsda=0x%" PRIxPTR ", personality=0x%" PRIxPTR "",
86 (void *)exception_object, pc, frameInfo.start_ip, functionName,
87 frameInfo.lsda, frameInfo.handler);
88 }
89
90 // If there is a personality routine, ask it if it will want to stop at
91 // this frame.
92 if (frameInfo.handler != 0) {
93 __personality_routine p =
94 (__personality_routine)(uintptr_t)(frameInfo.handler);
95 _LIBUNWIND_TRACE_UNWINDING(
96 "unwind_phase1(ex_ojb=%p): calling personality function %p",
97 (void *)exception_object, (void *)(uintptr_t)p);
98 _Unwind_Reason_Code personalityResult =
99 (*p)(1, _UA_SEARCH_PHASE, exception_object->exception_class,
100 exception_object, (struct _Unwind_Context *)(cursor));
101 switch (personalityResult) {
102 case _URC_HANDLER_FOUND:
103 // found a catch clause or locals that need destructing in this frame
104 // stop search and remember stack pointer at the frame
105 handlerNotFound = false;
106 __unw_get_reg(cursor, UNW_REG_SP, &sp);
107 exception_object->private_2 = (uintptr_t)sp;
108 _LIBUNWIND_TRACE_UNWINDING(
109 "unwind_phase1(ex_ojb=%p): _URC_HANDLER_FOUND",
110 (void *)exception_object);
111 return _URC_NO_REASON;
112
113 case _URC_CONTINUE_UNWIND:
114 _LIBUNWIND_TRACE_UNWINDING(
115 "unwind_phase1(ex_ojb=%p): _URC_CONTINUE_UNWIND",
116 (void *)exception_object);
117 // continue unwinding
118 break;
119
120 default:
121 // something went wrong
122 _LIBUNWIND_TRACE_UNWINDING(
123 "unwind_phase1(ex_ojb=%p): _URC_FATAL_PHASE1_ERROR",
124 (void *)exception_object);
125 return _URC_FATAL_PHASE1_ERROR;
126 }
127 }
128 }
129 return _URC_NO_REASON;
130}
131
132
133static _Unwind_Reason_Code
134unwind_phase2(unw_context_t *uc, unw_cursor_t *cursor, _Unwind_Exception *exception_object) {
135 __unw_init_local(cursor, uc);
136
137 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p)",
138 (void *)exception_object);
139
140 // Walk each frame until we reach where search phase said to stop.
141 while (true) {
142
143 // Ask libunwind to get next frame (skip over first which is
144 // _Unwind_RaiseException).
145 int stepResult = __unw_step(cursor);
146 if (stepResult == 0) {
147 _LIBUNWIND_TRACE_UNWINDING(
148 "unwind_phase2(ex_ojb=%p): __unw_step() reached "
149 "bottom => _URC_END_OF_STACK",
150 (void *)exception_object);
151 return _URC_END_OF_STACK;
152 } else if (stepResult < 0) {
153 _LIBUNWIND_TRACE_UNWINDING(
154 "unwind_phase2(ex_ojb=%p): __unw_step failed => "
155 "_URC_FATAL_PHASE1_ERROR",
156 (void *)exception_object);
157 return _URC_FATAL_PHASE2_ERROR;
158 }
159
160 // Get info about this frame.
161 unw_word_t sp;
162 unw_proc_info_t frameInfo;
163 __unw_get_reg(cursor, UNW_REG_SP, &sp);
164 if (__unw_get_proc_info(cursor, &frameInfo) != UNW_ESUCCESS) {
165 _LIBUNWIND_TRACE_UNWINDING(
166 "unwind_phase2(ex_ojb=%p): __unw_get_proc_info "
167 "failed => _URC_FATAL_PHASE1_ERROR",
168 (void *)exception_object);
169 return _URC_FATAL_PHASE2_ERROR;
170 }
171
172 // When tracing, print state information.
173 if (_LIBUNWIND_TRACING_UNWINDING) {
174 char functionBuf[512];
175 const char *functionName = functionBuf;
176 unw_word_t offset;
177 if ((__unw_get_proc_name(cursor, functionBuf, sizeof(functionBuf),
178 &offset) != UNW_ESUCCESS) ||
179 (frameInfo.start_ip + offset > frameInfo.end_ip))
180 functionName = ".anonymous.";
181 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): start_ip=0x%" PRIxPTR
182 ", func=%s, sp=0x%" PRIxPTR ", lsda=0x%" PRIxPTR
183 ", personality=0x%" PRIxPTR,
184 (void *)exception_object, frameInfo.start_ip,
185 functionName, sp, frameInfo.lsda,
186 frameInfo.handler);
187 }
188
189 // If there is a personality routine, tell it we are unwinding.
190 if (frameInfo.handler != 0) {
191 __personality_routine p =
192 (__personality_routine)(uintptr_t)(frameInfo.handler);
193 _Unwind_Action action = _UA_CLEANUP_PHASE;
194 if (sp == exception_object->private_2) {
195 // Tell personality this was the frame it marked in phase 1.
196 action = (_Unwind_Action)(_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME);
197 }
198 _Unwind_Reason_Code personalityResult =
199 (*p)(1, action, exception_object->exception_class, exception_object,
200 (struct _Unwind_Context *)(cursor));
201 switch (personalityResult) {
202 case _URC_CONTINUE_UNWIND:
203 // Continue unwinding
204 _LIBUNWIND_TRACE_UNWINDING(
205 "unwind_phase2(ex_ojb=%p): _URC_CONTINUE_UNWIND",
206 (void *)exception_object);
207 if (sp == exception_object->private_2) {
208 // Phase 1 said we would stop at this frame, but we did not...
209 _LIBUNWIND_ABORT("during phase1 personality function said it would "
210 "stop here, but now in phase2 it did not stop here");
211 }
212 break;
213 case _URC_INSTALL_CONTEXT:
214 _LIBUNWIND_TRACE_UNWINDING(
215 "unwind_phase2(ex_ojb=%p): _URC_INSTALL_CONTEXT",
216 (void *)exception_object);
217 // Personality routine says to transfer control to landing pad.
218 // We may get control back if landing pad calls _Unwind_Resume().
219 if (_LIBUNWIND_TRACING_UNWINDING) {
220 unw_word_t pc;
221 __unw_get_reg(cursor, UNW_REG_IP, &pc);
222 __unw_get_reg(cursor, UNW_REG_SP, &sp);
223 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): re-entering "
224 "user code with ip=0x%" PRIxPTR
225 ", sp=0x%" PRIxPTR,
226 (void *)exception_object, pc, sp);
227 }
228 __unw_resume(cursor);
229 // __unw_resume() only returns if there was an error.
230 return _URC_FATAL_PHASE2_ERROR;
231 default:
232 // Personality routine returned an unknown result code.
233 _LIBUNWIND_DEBUG_LOG("personality function returned unknown result %d",
234 personalityResult);
235 return _URC_FATAL_PHASE2_ERROR;
236 }
237 }
238 }
239
240 // Clean up phase did not resume at the frame that the search phase
241 // said it would...
242 return _URC_FATAL_PHASE2_ERROR;
243}
244
245static _Unwind_Reason_Code
246unwind_phase2_forced(unw_context_t *uc, unw_cursor_t *cursor,
247 _Unwind_Exception *exception_object,
248 _Unwind_Stop_Fn stop, void *stop_parameter) {
249 __unw_init_local(cursor, uc);
250
251 // Walk each frame until we reach where search phase said to stop
252 while (__unw_step(cursor) > 0) {
253
254 // Update info about this frame.
255 unw_proc_info_t frameInfo;
256 if (__unw_get_proc_info(cursor, &frameInfo) != UNW_ESUCCESS) {
257 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): __unw_step "
258 "failed => _URC_END_OF_STACK",
259 (void *)exception_object);
260 return _URC_FATAL_PHASE2_ERROR;
261 }
262
263 // When tracing, print state information.
264 if (_LIBUNWIND_TRACING_UNWINDING) {
265 char functionBuf[512];
266 const char *functionName = functionBuf;
267 unw_word_t offset;
268 if ((__unw_get_proc_name(cursor, functionBuf, sizeof(functionBuf),
269 &offset) != UNW_ESUCCESS) ||
270 (frameInfo.start_ip + offset > frameInfo.end_ip))
271 functionName = ".anonymous.";
272 _LIBUNWIND_TRACE_UNWINDING(
273 "unwind_phase2_forced(ex_ojb=%p): start_ip=0x%" PRIxPTR
274 ", func=%s, lsda=0x%" PRIxPTR ", personality=0x%" PRIxPTR,
275 (void *)exception_object, frameInfo.start_ip, functionName,
276 frameInfo.lsda, frameInfo.handler);
277 }
278
279 // Call stop function at each frame.
280 _Unwind_Action action =
281 (_Unwind_Action)(_UA_FORCE_UNWIND | _UA_CLEANUP_PHASE);
282 _Unwind_Reason_Code stopResult =
283 (*stop)(1, action, exception_object->exception_class, exception_object,
284 (struct _Unwind_Context *)(cursor), stop_parameter);
285 _LIBUNWIND_TRACE_UNWINDING(
286 "unwind_phase2_forced(ex_ojb=%p): stop function returned %d",
287 (void *)exception_object, stopResult);
288 if (stopResult != _URC_NO_REASON) {
289 _LIBUNWIND_TRACE_UNWINDING(
290 "unwind_phase2_forced(ex_ojb=%p): stopped by stop function",
291 (void *)exception_object);
292 return _URC_FATAL_PHASE2_ERROR;
293 }
294
295 // If there is a personality routine, tell it we are unwinding.
296 if (frameInfo.handler != 0) {
297 __personality_routine p =
298 (__personality_routine)(intptr_t)(frameInfo.handler);
299 _LIBUNWIND_TRACE_UNWINDING(
300 "unwind_phase2_forced(ex_ojb=%p): calling personality function %p",
301 (void *)exception_object, (void *)(uintptr_t)p);
302 _Unwind_Reason_Code personalityResult =
303 (*p)(1, action, exception_object->exception_class, exception_object,
304 (struct _Unwind_Context *)(cursor));
305 switch (personalityResult) {
306 case _URC_CONTINUE_UNWIND:
307 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
308 "personality returned "
309 "_URC_CONTINUE_UNWIND",
310 (void *)exception_object);
311 // Destructors called, continue unwinding
312 break;
313 case _URC_INSTALL_CONTEXT:
314 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
315 "personality returned "
316 "_URC_INSTALL_CONTEXT",
317 (void *)exception_object);
318 // We may get control back if landing pad calls _Unwind_Resume().
319 __unw_resume(cursor);
320 break;
321 default:
322 // Personality routine returned an unknown result code.
323 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
324 "personality returned %d, "
325 "_URC_FATAL_PHASE2_ERROR",
326 (void *)exception_object, personalityResult);
327 return _URC_FATAL_PHASE2_ERROR;
328 }
329 }
330 }
331
332 // Call stop function one last time and tell it we've reached the end
333 // of the stack.
334 _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): calling stop "
335 "function with _UA_END_OF_STACK",
336 (void *)exception_object);
337 _Unwind_Action lastAction =
338 (_Unwind_Action)(_UA_FORCE_UNWIND | _UA_CLEANUP_PHASE | _UA_END_OF_STACK);
339 (*stop)(1, lastAction, exception_object->exception_class, exception_object,
340 (struct _Unwind_Context *)(cursor), stop_parameter);
341
342 // Clean up phase did not resume at the frame that the search phase said it
343 // would.
344 return _URC_FATAL_PHASE2_ERROR;
345}
346
347
348/// Called by __cxa_throw. Only returns if there is a fatal error.
349_LIBUNWIND_EXPORT _Unwind_Reason_Code
350_Unwind_RaiseException(_Unwind_Exception *exception_object) {
351 _LIBUNWIND_TRACE_API("_Unwind_RaiseException(ex_obj=%p)",
352 (void *)exception_object);
353 unw_context_t uc;
354 unw_cursor_t cursor;
355 __unw_getcontext(&uc);
356
357 // Mark that this is a non-forced unwind, so _Unwind_Resume()
358 // can do the right thing.
359 exception_object->private_1 = 0;
360 exception_object->private_2 = 0;
361
362 // phase 1: the search phase
363 _Unwind_Reason_Code phase1 = unwind_phase1(&uc, &cursor, exception_object);
364 if (phase1 != _URC_NO_REASON)
365 return phase1;
366
367 // phase 2: the clean up phase
368 return unwind_phase2(&uc, &cursor, exception_object);
369}
370
371
372
373/// When _Unwind_RaiseException() is in phase2, it hands control
374/// to the personality function at each frame. The personality
375/// may force a jump to a landing pad in that function, the landing
376/// pad code may then call _Unwind_Resume() to continue with the
377/// unwinding. Note: the call to _Unwind_Resume() is from compiler
378/// geneated user code. All other _Unwind_* routines are called
379/// by the C++ runtime __cxa_* routines.
380///
381/// Note: re-throwing an exception (as opposed to continuing the unwind)
382/// is implemented by having the code call __cxa_rethrow() which
383/// in turn calls _Unwind_Resume_or_Rethrow().
384_LIBUNWIND_EXPORT void
385_Unwind_Resume(_Unwind_Exception *exception_object) {
386 _LIBUNWIND_TRACE_API("_Unwind_Resume(ex_obj=%p)", (void *)exception_object);
387 unw_context_t uc;
388 unw_cursor_t cursor;
389 __unw_getcontext(&uc);
390
391 if (exception_object->private_1 != 0)
392 unwind_phase2_forced(&uc, &cursor, exception_object,
393 (_Unwind_Stop_Fn) exception_object->private_1,
394 (void *)exception_object->private_2);
395 else
396 unwind_phase2(&uc, &cursor, exception_object);
397
398 // Clients assume _Unwind_Resume() does not return, so all we can do is abort.
399 _LIBUNWIND_ABORT("_Unwind_Resume() can't return");
400}
401
402
403
404/// Not used by C++.
405/// Unwinds stack, calling "stop" function at each frame.
406/// Could be used to implement longjmp().
407_LIBUNWIND_EXPORT _Unwind_Reason_Code
408_Unwind_ForcedUnwind(_Unwind_Exception *exception_object,
409 _Unwind_Stop_Fn stop, void *stop_parameter) {
410 _LIBUNWIND_TRACE_API("_Unwind_ForcedUnwind(ex_obj=%p, stop=%p)",
411 (void *)exception_object, (void *)(uintptr_t)stop);
412 unw_context_t uc;
413 unw_cursor_t cursor;
414 __unw_getcontext(&uc);
415
416 // Mark that this is a forced unwind, so _Unwind_Resume() can do
417 // the right thing.
418 exception_object->private_1 = (uintptr_t) stop;
419 exception_object->private_2 = (uintptr_t) stop_parameter;
420
421 // do it
422 return unwind_phase2_forced(&uc, &cursor, exception_object, stop, stop_parameter);
423}
424
425
426/// Called by personality handler during phase 2 to get LSDA for current frame.
427_LIBUNWIND_EXPORT uintptr_t
428_Unwind_GetLanguageSpecificData(struct _Unwind_Context *context) {
429 unw_cursor_t *cursor = (unw_cursor_t *)context;
430 unw_proc_info_t frameInfo;
431 uintptr_t result = 0;
432 if (__unw_get_proc_info(cursor, &frameInfo) == UNW_ESUCCESS)
433 result = (uintptr_t)frameInfo.lsda;
434 _LIBUNWIND_TRACE_API(
435 "_Unwind_GetLanguageSpecificData(context=%p) => 0x%" PRIxPTR,
436 (void *)context, result);
437 if (result != 0) {
438 if (*((uint8_t *)result) != 0xFF)
439 _LIBUNWIND_DEBUG_LOG("lsda at 0x%" PRIxPTR " does not start with 0xFF",
440 result);
441 }
442 return result;
443}
444
445
446/// Called by personality handler during phase 2 to find the start of the
447/// function.
448_LIBUNWIND_EXPORT uintptr_t
449_Unwind_GetRegionStart(struct _Unwind_Context *context) {
450 unw_cursor_t *cursor = (unw_cursor_t *)context;
451 unw_proc_info_t frameInfo;
452 uintptr_t result = 0;
453 if (__unw_get_proc_info(cursor, &frameInfo) == UNW_ESUCCESS)
454 result = (uintptr_t)frameInfo.start_ip;
455 _LIBUNWIND_TRACE_API("_Unwind_GetRegionStart(context=%p) => 0x%" PRIxPTR,
456 (void *)context, result);
457 return result;
458}
459
460#endif // !_LIBUNWIND_SUPPORT_SEH_UNWIND
461
462/// Called by personality handler during phase 2 if a foreign exception
463// is caught.
464_LIBUNWIND_EXPORT void
465_Unwind_DeleteException(_Unwind_Exception *exception_object) {
466 _LIBUNWIND_TRACE_API("_Unwind_DeleteException(ex_obj=%p)",
467 (void *)exception_object);
468 if (exception_object->exception_cleanup != NULL)
469 (*exception_object->exception_cleanup)(_URC_FOREIGN_EXCEPTION_CAUGHT,
470 exception_object);
471}
472
473/// Called by personality handler during phase 2 to get register values.
474_LIBUNWIND_EXPORT uintptr_t
475_Unwind_GetGR(struct _Unwind_Context *context, int index) {
476 unw_cursor_t *cursor = (unw_cursor_t *)context;
477 unw_word_t result;
478 __unw_get_reg(cursor, index, &result);
479 _LIBUNWIND_TRACE_API("_Unwind_GetGR(context=%p, reg=%d) => 0x%" PRIxPTR,
480 (void *)context, index, result);
481 return (uintptr_t)result;
482}
483
484/// Called by personality handler during phase 2 to alter register values.
485_LIBUNWIND_EXPORT void _Unwind_SetGR(struct _Unwind_Context *context, int index,
486 uintptr_t value) {
487 _LIBUNWIND_TRACE_API("_Unwind_SetGR(context=%p, reg=%d, value=0x%0" PRIxPTR
488 ")",
489 (void *)context, index, value);
490 unw_cursor_t *cursor = (unw_cursor_t *)context;
491 __unw_set_reg(cursor, index, value);
492}
493
494/// Called by personality handler during phase 2 to get instruction pointer.
495_LIBUNWIND_EXPORT uintptr_t _Unwind_GetIP(struct _Unwind_Context *context) {
496 unw_cursor_t *cursor = (unw_cursor_t *)context;
497 unw_word_t result;
498 __unw_get_reg(cursor, UNW_REG_IP, &result);
499 _LIBUNWIND_TRACE_API("_Unwind_GetIP(context=%p) => 0x%" PRIxPTR,
500 (void *)context, result);
501 return (uintptr_t)result;
502}
503
504/// Called by personality handler during phase 2 to alter instruction pointer,
505/// such as setting where the landing pad is, so _Unwind_Resume() will
506/// start executing in the landing pad.
507_LIBUNWIND_EXPORT void _Unwind_SetIP(struct _Unwind_Context *context,
508 uintptr_t value) {
509 _LIBUNWIND_TRACE_API("_Unwind_SetIP(context=%p, value=0x%0" PRIxPTR ")",
510 (void *)context, value);
511 unw_cursor_t *cursor = (unw_cursor_t *)context;
512 __unw_set_reg(cursor, UNW_REG_IP, value);
513}
514
515#endif // !defined(_LIBUNWIND_ARM_EHABI) && !defined(__USING_SJLJ_EXCEPTIONS__)
516