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1//===----------------------------------------------------------------------===//
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// This file implements the "Exception Handling APIs"
9// https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html
10// http://www.intel.com/design/itanium/downloads/245358.htm
11//
12//===----------------------------------------------------------------------===//
13
14#include <assert.h>
15#include <stdlib.h>
16#include <string.h>
17#include <typeinfo>
18
19#include "__cxxabi_config.h"
20#include "cxa_exception.h"
21#include "cxa_handlers.h"
22#include "private_typeinfo.h"
23#include "unwind.h"
24
25// TODO: This is a temporary workaround for libc++abi to recognize that it's being
26// built against LLVM's libunwind. LLVM's libunwind started reporting _LIBUNWIND_VERSION
27// in LLVM 15 -- we can remove this workaround after shipping LLVM 17. Once we remove
28// this workaround, it won't be possible to build libc++abi against libunwind headers
29// from LLVM 14 and before anymore.
30#if defined(____LIBUNWIND_CONFIG_H__) && !defined(_LIBUNWIND_VERSION)
31# define _LIBUNWIND_VERSION
32#endif
33
34#if defined(__SEH__) && !defined(__USING_SJLJ_EXCEPTIONS__)
35#include <windows.h>
36#include <winnt.h>
37
38extern "C" EXCEPTION_DISPOSITION _GCC_specific_handler(PEXCEPTION_RECORD,
39 void *, PCONTEXT,
40 PDISPATCHER_CONTEXT,
41 _Unwind_Personality_Fn);
42#endif
43
44/*
45 Exception Header Layout:
46
47+---------------------------+-----------------------------+---------------+
48| __cxa_exception | _Unwind_Exception CLNGC++\0 | thrown object |
49+---------------------------+-----------------------------+---------------+
50 ^
51 |
52 +-------------------------------------------------------+
53 |
54+---------------------------+-----------------------------+
55| __cxa_dependent_exception | _Unwind_Exception CLNGC++\1 |
56+---------------------------+-----------------------------+
57
58 Exception Handling Table Layout:
59
60+-----------------+--------+
61| lpStartEncoding | (char) |
62+---------+-------+--------+---------------+-----------------------+
63| lpStart | (encoded with lpStartEncoding) | defaults to funcStart |
64+---------+-----+--------+-----------------+---------------+-------+
65| ttypeEncoding | (char) | Encoding of the type_info table |
66+---------------+-+------+----+----------------------------+----------------+
67| classInfoOffset | (ULEB128) | Offset to type_info table, defaults to null |
68+-----------------++--------+-+----------------------------+----------------+
69| callSiteEncoding | (char) | Encoding for Call Site Table |
70+------------------+--+-----+-----+------------------------+--------------------------+
71| callSiteTableLength | (ULEB128) | Call Site Table length, used to find Action table |
72+---------------------+-----------+---------------------------------------------------+
73#if !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__WASM_EXCEPTIONS__)
74+---------------------+-----------+------------------------------------------------+
75| Beginning of Call Site Table The current ip lies within the |
76| ... (start, length) range of one of these |
77| call sites. There may be action needed. |
78| +-------------+---------------------------------+------------------------------+ |
79| | start | (encoded with callSiteEncoding) | offset relative to funcStart | |
80| | length | (encoded with callSiteEncoding) | length of code fragment | |
81| | landingPad | (encoded with callSiteEncoding) | offset relative to lpStart | |
82| | actionEntry | (ULEB128) | Action Table Index 1-based | |
83| | | | actionEntry == 0 -> cleanup | |
84| +-------------+---------------------------------+------------------------------+ |
85| ... |
86+----------------------------------------------------------------------------------+
87#else // __USING_SJLJ_EXCEPTIONS__ || __WASM_EXCEPTIONS__
88+---------------------+-----------+------------------------------------------------+
89| Beginning of Call Site Table The current ip is a 1-based index into |
90| ... this table. Or it is -1 meaning no |
91| action is needed. Or it is 0 meaning |
92| terminate. |
93| +-------------+---------------------------------+------------------------------+ |
94| | landingPad | (ULEB128) | offset relative to lpStart | |
95| | actionEntry | (ULEB128) | Action Table Index 1-based | |
96| | | | actionEntry == 0 -> cleanup | |
97| +-------------+---------------------------------+------------------------------+ |
98| ... |
99+----------------------------------------------------------------------------------+
100#endif // __USING_SJLJ_EXCEPTIONS__ || __WASM_EXCEPTIONS__
101+---------------------------------------------------------------------+
102| Beginning of Action Table ttypeIndex == 0 : cleanup |
103| ... ttypeIndex > 0 : catch |
104| ttypeIndex < 0 : exception spec |
105| +--------------+-----------+--------------------------------------+ |
106| | ttypeIndex | (SLEB128) | Index into type_info Table (1-based) | |
107| | actionOffset | (SLEB128) | Offset into next Action Table entry | |
108| +--------------+-----------+--------------------------------------+ |
109| ... |
110+---------------------------------------------------------------------+-----------------+
111| type_info Table, but classInfoOffset does *not* point here! |
112| +----------------+------------------------------------------------+-----------------+ |
113| | Nth type_info* | Encoded with ttypeEncoding, 0 means catch(...) | ttypeIndex == N | |
114| +----------------+------------------------------------------------+-----------------+ |
115| ... |
116| +----------------+------------------------------------------------+-----------------+ |
117| | 1st type_info* | Encoded with ttypeEncoding, 0 means catch(...) | ttypeIndex == 1 | |
118| +----------------+------------------------------------------------+-----------------+ |
119| +---------------------------------------+-----------+------------------------------+ |
120| | 1st ttypeIndex for 1st exception spec | (ULEB128) | classInfoOffset points here! | |
121| | ... | (ULEB128) | | |
122| | Mth ttypeIndex for 1st exception spec | (ULEB128) | | |
123| | 0 | (ULEB128) | | |
124| +---------------------------------------+------------------------------------------+ |
125| ... |
126| +---------------------------------------+------------------------------------------+ |
127| | 0 | (ULEB128) | throw() | |
128| +---------------------------------------+------------------------------------------+ |
129| ... |
130| +---------------------------------------+------------------------------------------+ |
131| | 1st ttypeIndex for Nth exception spec | (ULEB128) | | |
132| | ... | (ULEB128) | | |
133| | Mth ttypeIndex for Nth exception spec | (ULEB128) | | |
134| | 0 | (ULEB128) | | |
135| +---------------------------------------+------------------------------------------+ |
136+---------------------------------------------------------------------------------------+
137
138Notes:
139
140* ttypeIndex in the Action Table, and in the exception spec table, is an index,
141 not a byte count, if positive. It is a negative index offset of
142 classInfoOffset and the sizeof entry depends on ttypeEncoding.
143 But if ttypeIndex is negative, it is a positive 1-based byte offset into the
144 type_info Table.
145 And if ttypeIndex is zero, it refers to a catch (...).
146
147* landingPad can be 0, this implies there is nothing to be done.
148
149* landingPad != 0 and actionEntry == 0 implies a cleanup needs to be done
150 @landingPad.
151
152* A cleanup can also be found under landingPad != 0 and actionEntry != 0 in
153 the Action Table with ttypeIndex == 0.
154*/
155
156namespace __cxxabiv1
157{
158
159namespace
160{
161
162template <class AsType>
163uintptr_t readPointerHelper(const uint8_t*& p) {
164 AsType value;
165 memcpy(&value, p, sizeof(AsType));
166 p += sizeof(AsType);
167 return static_cast<uintptr_t>(value);
168}
169
170} // namespace
171
172extern "C"
173{
174
175// private API
176
177// Heavily borrowed from llvm/examples/ExceptionDemo/ExceptionDemo.cpp
178
179// DWARF Constants
180enum
181{
182 DW_EH_PE_absptr = 0x00,
183 DW_EH_PE_uleb128 = 0x01,
184 DW_EH_PE_udata2 = 0x02,
185 DW_EH_PE_udata4 = 0x03,
186 DW_EH_PE_udata8 = 0x04,
187 DW_EH_PE_sleb128 = 0x09,
188 DW_EH_PE_sdata2 = 0x0A,
189 DW_EH_PE_sdata4 = 0x0B,
190 DW_EH_PE_sdata8 = 0x0C,
191 DW_EH_PE_pcrel = 0x10,
192 DW_EH_PE_textrel = 0x20,
193 DW_EH_PE_datarel = 0x30,
194 DW_EH_PE_funcrel = 0x40,
195 DW_EH_PE_aligned = 0x50,
196 DW_EH_PE_indirect = 0x80,
197 DW_EH_PE_omit = 0xFF
198};
199
200/// Read a uleb128 encoded value and advance pointer
201/// See Variable Length Data Appendix C in:
202/// @link http://dwarfstd.org/Dwarf4.pdf @unlink
203/// @param data reference variable holding memory pointer to decode from
204/// @returns decoded value
205static
206uintptr_t
207readULEB128(const uint8_t** data)
208{
209 uintptr_t result = 0;
210 uintptr_t shift = 0;
211 unsigned char byte;
212 const uint8_t *p = *data;
213 do
214 {
215 byte = *p++;
216 result |= static_cast<uintptr_t>(byte & 0x7F) << shift;
217 shift += 7;
218 } while (byte & 0x80);
219 *data = p;
220 return result;
221}
222
223/// Read a sleb128 encoded value and advance pointer
224/// See Variable Length Data Appendix C in:
225/// @link http://dwarfstd.org/Dwarf4.pdf @unlink
226/// @param data reference variable holding memory pointer to decode from
227/// @returns decoded value
228static
229intptr_t
230readSLEB128(const uint8_t** data)
231{
232 uintptr_t result = 0;
233 uintptr_t shift = 0;
234 unsigned char byte;
235 const uint8_t *p = *data;
236 do
237 {
238 byte = *p++;
239 result |= static_cast<uintptr_t>(byte & 0x7F) << shift;
240 shift += 7;
241 } while (byte & 0x80);
242 *data = p;
243 if ((byte & 0x40) && (shift < (sizeof(result) << 3)))
244 result |= static_cast<uintptr_t>(~0) << shift;
245 return static_cast<intptr_t>(result);
246}
247
248/// Read a pointer encoded value and advance pointer
249/// See Variable Length Data in:
250/// @link http://dwarfstd.org/Dwarf3.pdf @unlink
251/// @param data reference variable holding memory pointer to decode from
252/// @param encoding dwarf encoding type
253/// @param base for adding relative offset, default to 0
254/// @returns decoded value
255static
256uintptr_t
257readEncodedPointer(const uint8_t** data, uint8_t encoding, uintptr_t base = 0)
258{
259 uintptr_t result = 0;
260 if (encoding == DW_EH_PE_omit)
261 return result;
262 const uint8_t* p = *data;
263 // first get value
264 switch (encoding & 0x0F)
265 {
266 case DW_EH_PE_absptr:
267 result = readPointerHelper<uintptr_t>(p);
268 break;
269 case DW_EH_PE_uleb128:
270 result = readULEB128(&p);
271 break;
272 case DW_EH_PE_sleb128:
273 result = static_cast<uintptr_t>(readSLEB128(&p));
274 break;
275 case DW_EH_PE_udata2:
276 result = readPointerHelper<uint16_t>(p);
277 break;
278 case DW_EH_PE_udata4:
279 result = readPointerHelper<uint32_t>(p);
280 break;
281 case DW_EH_PE_udata8:
282 result = readPointerHelper<uint64_t>(p);
283 break;
284 case DW_EH_PE_sdata2:
285 result = readPointerHelper<int16_t>(p);
286 break;
287 case DW_EH_PE_sdata4:
288 result = readPointerHelper<int32_t>(p);
289 break;
290 case DW_EH_PE_sdata8:
291 result = readPointerHelper<int64_t>(p);
292 break;
293 default:
294 // not supported
295 abort();
296 break;
297 }
298 // then add relative offset
299 switch (encoding & 0x70)
300 {
301 case DW_EH_PE_absptr:
302 // do nothing
303 break;
304 case DW_EH_PE_pcrel:
305 if (result)
306 result += (uintptr_t)(*data);
307 break;
308 case DW_EH_PE_datarel:
309 assert((base != 0) && "DW_EH_PE_datarel is invalid with a base of 0");
310 if (result)
311 result += base;
312 break;
313 case DW_EH_PE_textrel:
314 case DW_EH_PE_funcrel:
315 case DW_EH_PE_aligned:
316 default:
317 // not supported
318 abort();
319 break;
320 }
321 // then apply indirection
322 if (result && (encoding & DW_EH_PE_indirect))
323 result = *((uintptr_t*)result);
324 *data = p;
325 return result;
326}
327
328static
329void
330call_terminate(bool native_exception, _Unwind_Exception* unwind_exception)
331{
332 __cxa_begin_catch(unwind_exception);
333 if (native_exception)
334 {
335 // Use the stored terminate_handler if possible
336 __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1;
337 std::__terminate(exception_header->terminateHandler);
338 }
339 std::terminate();
340}
341
342#if defined(_LIBCXXABI_ARM_EHABI)
343static const void* read_target2_value(const void* ptr)
344{
345 uintptr_t offset = *reinterpret_cast<const uintptr_t*>(ptr);
346 if (!offset)
347 return 0;
348 // "ARM EABI provides a TARGET2 relocation to describe these typeinfo
349 // pointers. The reason being it allows their precise semantics to be
350 // deferred to the linker. For bare-metal they turn into absolute
351 // relocations. For linux they turn into GOT-REL relocations."
352 // https://gcc.gnu.org/ml/gcc-patches/2009-08/msg00264.html
353#if defined(LIBCXXABI_BAREMETAL)
354 return reinterpret_cast<const void*>(reinterpret_cast<uintptr_t>(ptr) +
355 offset);
356#else
357 return *reinterpret_cast<const void **>(reinterpret_cast<uintptr_t>(ptr) +
358 offset);
359#endif
360}
361
362static const __shim_type_info*
363get_shim_type_info(uint64_t ttypeIndex, const uint8_t* classInfo,
364 uint8_t ttypeEncoding, bool native_exception,
365 _Unwind_Exception* unwind_exception, uintptr_t /*base*/ = 0)
366{
367 if (classInfo == 0)
368 {
369 // this should not happen. Indicates corrupted eh_table.
370 call_terminate(native_exception, unwind_exception);
371 }
372
373 assert(((ttypeEncoding == DW_EH_PE_absptr) || // LLVM or GCC 4.6
374 (ttypeEncoding == DW_EH_PE_pcrel) || // GCC 4.7 baremetal
375 (ttypeEncoding == (DW_EH_PE_pcrel | DW_EH_PE_indirect))) && // GCC 4.7 linux
376 "Unexpected TTypeEncoding");
377 (void)ttypeEncoding;
378
379 const uint8_t* ttypePtr = classInfo - ttypeIndex * sizeof(uintptr_t);
380 return reinterpret_cast<const __shim_type_info *>(
381 read_target2_value(ttypePtr));
382}
383#else // !defined(_LIBCXXABI_ARM_EHABI)
384static
385const __shim_type_info*
386get_shim_type_info(uint64_t ttypeIndex, const uint8_t* classInfo,
387 uint8_t ttypeEncoding, bool native_exception,
388 _Unwind_Exception* unwind_exception, uintptr_t base = 0)
389{
390 if (classInfo == 0)
391 {
392 // this should not happen. Indicates corrupted eh_table.
393 call_terminate(native_exception, unwind_exception);
394 }
395 switch (ttypeEncoding & 0x0F)
396 {
397 case DW_EH_PE_absptr:
398 ttypeIndex *= sizeof(void*);
399 break;
400 case DW_EH_PE_udata2:
401 case DW_EH_PE_sdata2:
402 ttypeIndex *= 2;
403 break;
404 case DW_EH_PE_udata4:
405 case DW_EH_PE_sdata4:
406 ttypeIndex *= 4;
407 break;
408 case DW_EH_PE_udata8:
409 case DW_EH_PE_sdata8:
410 ttypeIndex *= 8;
411 break;
412 default:
413 // this should not happen. Indicates corrupted eh_table.
414 call_terminate(native_exception, unwind_exception);
415 }
416 classInfo -= ttypeIndex;
417 return (const __shim_type_info*)readEncodedPointer(&classInfo,
418 ttypeEncoding, base);
419}
420#endif // !defined(_LIBCXXABI_ARM_EHABI)
421
422/*
423 This is checking a thrown exception type, excpType, against a possibly empty
424 list of catchType's which make up an exception spec.
425
426 An exception spec acts like a catch handler, but in reverse. This "catch
427 handler" will catch an excpType if and only if none of the catchType's in
428 the list will catch a excpType. If any catchType in the list can catch an
429 excpType, then this exception spec does not catch the excpType.
430*/
431#if defined(_LIBCXXABI_ARM_EHABI)
432static
433bool
434exception_spec_can_catch(int64_t specIndex, const uint8_t* classInfo,
435 uint8_t ttypeEncoding, const __shim_type_info* excpType,
436 void* adjustedPtr, _Unwind_Exception* unwind_exception,
437 uintptr_t /*base*/ = 0)
438{
439 if (classInfo == 0)
440 {
441 // this should not happen. Indicates corrupted eh_table.
442 call_terminate(false, unwind_exception);
443 }
444
445 assert(((ttypeEncoding == DW_EH_PE_absptr) || // LLVM or GCC 4.6
446 (ttypeEncoding == DW_EH_PE_pcrel) || // GCC 4.7 baremetal
447 (ttypeEncoding == (DW_EH_PE_pcrel | DW_EH_PE_indirect))) && // GCC 4.7 linux
448 "Unexpected TTypeEncoding");
449 (void)ttypeEncoding;
450
451 // specIndex is negative of 1-based byte offset into classInfo;
452 specIndex = -specIndex;
453 --specIndex;
454 const void** temp = reinterpret_cast<const void**>(
455 reinterpret_cast<uintptr_t>(classInfo) +
456 static_cast<uintptr_t>(specIndex) * sizeof(uintptr_t));
457 // If any type in the spec list can catch excpType, return false, else return true
458 // adjustments to adjustedPtr are ignored.
459 while (true)
460 {
461 // ARM EHABI exception specification table (filter table) consists of
462 // several pointers which will directly point to the type info object
463 // (instead of ttypeIndex). The table will be terminated with 0.
464 const void** ttypePtr = temp++;
465 if (*ttypePtr == 0)
466 break;
467 // We can get the __shim_type_info simply by performing a
468 // R_ARM_TARGET2 relocation, and cast the result to __shim_type_info.
469 const __shim_type_info* catchType =
470 static_cast<const __shim_type_info*>(read_target2_value(ttypePtr));
471 void* tempPtr = adjustedPtr;
472 if (catchType->can_catch(excpType, tempPtr))
473 return false;
474 }
475 return true;
476}
477#else
478static
479bool
480exception_spec_can_catch(int64_t specIndex, const uint8_t* classInfo,
481 uint8_t ttypeEncoding, const __shim_type_info* excpType,
482 void* adjustedPtr, _Unwind_Exception* unwind_exception,
483 uintptr_t base = 0)
484{
485 if (classInfo == 0)
486 {
487 // this should not happen. Indicates corrupted eh_table.
488 call_terminate(false, unwind_exception);
489 }
490 // specIndex is negative of 1-based byte offset into classInfo;
491 specIndex = -specIndex;
492 --specIndex;
493 const uint8_t* temp = classInfo + specIndex;
494 // If any type in the spec list can catch excpType, return false, else return true
495 // adjustments to adjustedPtr are ignored.
496 while (true)
497 {
498 uint64_t ttypeIndex = readULEB128(&temp);
499 if (ttypeIndex == 0)
500 break;
501 const __shim_type_info* catchType = get_shim_type_info(ttypeIndex,
502 classInfo,
503 ttypeEncoding,
504 true,
505 unwind_exception,
506 base);
507 void* tempPtr = adjustedPtr;
508 if (catchType->can_catch(excpType, tempPtr))
509 return false;
510 }
511 return true;
512}
513#endif
514
515static
516void*
517get_thrown_object_ptr(_Unwind_Exception* unwind_exception)
518{
519 // Even for foreign exceptions, the exception object is *probably* at unwind_exception + 1
520 // Regardless, this library is prohibited from touching a foreign exception
521 void* adjustedPtr = unwind_exception + 1;
522 if (__getExceptionClass(unwind_exception) == kOurDependentExceptionClass)
523 adjustedPtr = ((__cxa_dependent_exception*)adjustedPtr - 1)->primaryException;
524 return adjustedPtr;
525}
526
527namespace
528{
529
530struct scan_results
531{
532 int64_t ttypeIndex; // > 0 catch handler, < 0 exception spec handler, == 0 a cleanup
533 const uint8_t* actionRecord; // Currently unused. Retained to ease future maintenance.
534 const uint8_t* languageSpecificData; // Needed only for __cxa_call_unexpected
535 uintptr_t landingPad; // null -> nothing found, else something found
536 void* adjustedPtr; // Used in cxa_exception.cpp
537 _Unwind_Reason_Code reason; // One of _URC_FATAL_PHASE1_ERROR,
538 // _URC_FATAL_PHASE2_ERROR,
539 // _URC_CONTINUE_UNWIND,
540 // _URC_HANDLER_FOUND
541};
542
543} // unnamed namespace
544
545static
546void
547set_registers(_Unwind_Exception* unwind_exception, _Unwind_Context* context,
548 const scan_results& results)
549{
550#if defined(__USING_SJLJ_EXCEPTIONS__) || defined(__WASM_EXCEPTIONS__)
551#define __builtin_eh_return_data_regno(regno) regno
552#elif defined(__ibmxl__)
553// IBM xlclang++ compiler does not support __builtin_eh_return_data_regno.
554#define __builtin_eh_return_data_regno(regno) regno + 3
555#endif
556 _Unwind_SetGR(context, __builtin_eh_return_data_regno(0),
557 reinterpret_cast<uintptr_t>(unwind_exception));
558 _Unwind_SetGR(context, __builtin_eh_return_data_regno(1),
559 static_cast<uintptr_t>(results.ttypeIndex));
560 _Unwind_SetIP(context, results.landingPad);
561}
562
563/*
564 There are 3 types of scans needed:
565
566 1. Scan for handler with native or foreign exception. If handler found,
567 save state and return _URC_HANDLER_FOUND, else return _URC_CONTINUE_UNWIND.
568 May also report an error on invalid input.
569 May terminate for invalid exception table.
570 _UA_SEARCH_PHASE
571
572 2. Scan for handler with foreign exception. Must return _URC_HANDLER_FOUND,
573 or call terminate.
574 _UA_CLEANUP_PHASE && _UA_HANDLER_FRAME && !native_exception
575
576 3. Scan for cleanups. If a handler is found and this isn't forced unwind,
577 then terminate, otherwise ignore the handler and keep looking for cleanup.
578 If a cleanup is found, return _URC_HANDLER_FOUND, else return _URC_CONTINUE_UNWIND.
579 May also report an error on invalid input.
580 May terminate for invalid exception table.
581 _UA_CLEANUP_PHASE && !_UA_HANDLER_FRAME
582*/
583
584static void scan_eh_tab(scan_results &results, _Unwind_Action actions,
585 bool native_exception,
586 _Unwind_Exception *unwind_exception,
587 _Unwind_Context *context) {
588 // Initialize results to found nothing but an error
589 results.ttypeIndex = 0;
590 results.actionRecord = 0;
591 results.languageSpecificData = 0;
592 results.landingPad = 0;
593 results.adjustedPtr = 0;
594 results.reason = _URC_FATAL_PHASE1_ERROR;
595 // Check for consistent actions
596 if (actions & _UA_SEARCH_PHASE)
597 {
598 // Do Phase 1
599 if (actions & (_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME | _UA_FORCE_UNWIND))
600 {
601 // None of these flags should be set during Phase 1
602 // Client error
603 results.reason = _URC_FATAL_PHASE1_ERROR;
604 return;
605 }
606 }
607 else if (actions & _UA_CLEANUP_PHASE)
608 {
609 if ((actions & _UA_HANDLER_FRAME) && (actions & _UA_FORCE_UNWIND))
610 {
611 // _UA_HANDLER_FRAME should only be set if phase 1 found a handler.
612 // If _UA_FORCE_UNWIND is set, phase 1 shouldn't have happened.
613 // Client error
614 results.reason = _URC_FATAL_PHASE2_ERROR;
615 return;
616 }
617 }
618 else // Neither _UA_SEARCH_PHASE nor _UA_CLEANUP_PHASE is set
619 {
620 // One of these should be set.
621 // Client error
622 results.reason = _URC_FATAL_PHASE1_ERROR;
623 return;
624 }
625 // Start scan by getting exception table address.
626 const uint8_t *lsda = (const uint8_t *)_Unwind_GetLanguageSpecificData(context);
627 if (lsda == 0)
628 {
629 // There is no exception table
630 results.reason = _URC_CONTINUE_UNWIND;
631 return;
632 }
633 results.languageSpecificData = lsda;
634#if defined(_AIX)
635 uintptr_t base = _Unwind_GetDataRelBase(context);
636#else
637 uintptr_t base = 0;
638#endif
639 // Get the current instruction pointer and offset it before next
640 // instruction in the current frame which threw the exception.
641 uintptr_t ip = _Unwind_GetIP(context) - 1;
642 // Get beginning current frame's code (as defined by the
643 // emitted dwarf code)
644 uintptr_t funcStart = _Unwind_GetRegionStart(context);
645#if defined(__USING_SJLJ_EXCEPTIONS__) || defined(__WASM_EXCEPTIONS__)
646 if (ip == uintptr_t(-1))
647 {
648 // no action
649 results.reason = _URC_CONTINUE_UNWIND;
650 return;
651 }
652 else if (ip == 0)
653 call_terminate(native_exception, unwind_exception);
654 // ip is 1-based index into call site table
655#else // !__USING_SJLJ_EXCEPTIONS__ && !__WASM_EXCEPTIONS__
656 uintptr_t ipOffset = ip - funcStart;
657#endif // !__USING_SJLJ_EXCEPTIONS__ && !__WASM_EXCEPTIONS__
658 const uint8_t* classInfo = NULL;
659 // Note: See JITDwarfEmitter::EmitExceptionTable(...) for corresponding
660 // dwarf emission
661 // Parse LSDA header.
662 uint8_t lpStartEncoding = *lsda++;
663 const uint8_t* lpStart = lpStartEncoding == DW_EH_PE_omit
664 ? (const uint8_t*)funcStart
665 : (const uint8_t*)readEncodedPointer(&lsda, lpStartEncoding, base);
666 uint8_t ttypeEncoding = *lsda++;
667 if (ttypeEncoding != DW_EH_PE_omit)
668 {
669 // Calculate type info locations in emitted dwarf code which
670 // were flagged by type info arguments to llvm.eh.selector
671 // intrinsic
672 uintptr_t classInfoOffset = readULEB128(&lsda);
673 classInfo = lsda + classInfoOffset;
674 }
675 // Walk call-site table looking for range that
676 // includes current PC.
677 uint8_t callSiteEncoding = *lsda++;
678#if defined(__USING_SJLJ_EXCEPTIONS__) || defined(__WASM_EXCEPTIONS__)
679 (void)callSiteEncoding; // When using SjLj/Wasm exceptions, callSiteEncoding is never used
680#endif
681 uint32_t callSiteTableLength = static_cast<uint32_t>(readULEB128(&lsda));
682 const uint8_t* callSiteTableStart = lsda;
683 const uint8_t* callSiteTableEnd = callSiteTableStart + callSiteTableLength;
684 const uint8_t* actionTableStart = callSiteTableEnd;
685 const uint8_t* callSitePtr = callSiteTableStart;
686 while (callSitePtr < callSiteTableEnd)
687 {
688 // There is one entry per call site.
689#if !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__WASM_EXCEPTIONS__)
690 // The call sites are non-overlapping in [start, start+length)
691 // The call sites are ordered in increasing value of start
692 uintptr_t start = readEncodedPointer(&callSitePtr, callSiteEncoding);
693 uintptr_t length = readEncodedPointer(&callSitePtr, callSiteEncoding);
694 uintptr_t landingPad = readEncodedPointer(&callSitePtr, callSiteEncoding);
695 uintptr_t actionEntry = readULEB128(&callSitePtr);
696 if ((start <= ipOffset) && (ipOffset < (start + length)))
697#else // __USING_SJLJ_EXCEPTIONS__ || __WASM_EXCEPTIONS__
698 // ip is 1-based index into this table
699 uintptr_t landingPad = readULEB128(&callSitePtr);
700 uintptr_t actionEntry = readULEB128(&callSitePtr);
701 if (--ip == 0)
702#endif // __USING_SJLJ_EXCEPTIONS__ || __WASM_EXCEPTIONS__
703 {
704 // Found the call site containing ip.
705#if !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__WASM_EXCEPTIONS__)
706 if (landingPad == 0)
707 {
708 // No handler here
709 results.reason = _URC_CONTINUE_UNWIND;
710 return;
711 }
712 landingPad = (uintptr_t)lpStart + landingPad;
713#else // __USING_SJLJ_EXCEPTIONS__ || __WASM_EXCEPTIONS__
714 ++landingPad;
715#endif // __USING_SJLJ_EXCEPTIONS__ || __WASM_EXCEPTIONS__
716 results.landingPad = landingPad;
717 if (actionEntry == 0)
718 {
719 // Found a cleanup
720 results.reason = (actions & _UA_SEARCH_PHASE) ? _URC_CONTINUE_UNWIND : _URC_HANDLER_FOUND;
721 return;
722 }
723 // Convert 1-based byte offset into
724 const uint8_t* action = actionTableStart + (actionEntry - 1);
725 bool hasCleanup = false;
726 // Scan action entries until you find a matching handler, cleanup, or the end of action list
727 while (true)
728 {
729 const uint8_t* actionRecord = action;
730 int64_t ttypeIndex = readSLEB128(&action);
731 if (ttypeIndex > 0)
732 {
733 // Found a catch, does it actually catch?
734 // First check for catch (...)
735 const __shim_type_info* catchType =
736 get_shim_type_info(static_cast<uint64_t>(ttypeIndex),
737 classInfo, ttypeEncoding,
738 native_exception, unwind_exception,
739 base);
740 if (catchType == 0)
741 {
742 // Found catch (...) catches everything, including
743 // foreign exceptions. This is search phase, cleanup
744 // phase with foreign exception, or forced unwinding.
745 assert(actions & (_UA_SEARCH_PHASE | _UA_HANDLER_FRAME |
746 _UA_FORCE_UNWIND));
747 results.ttypeIndex = ttypeIndex;
748 results.actionRecord = actionRecord;
749 results.adjustedPtr =
750 get_thrown_object_ptr(unwind_exception);
751 results.reason = _URC_HANDLER_FOUND;
752 return;
753 }
754 // Else this is a catch (T) clause and will never
755 // catch a foreign exception
756 else if (native_exception)
757 {
758 __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1;
759 void* adjustedPtr = get_thrown_object_ptr(unwind_exception);
760 const __shim_type_info* excpType =
761 static_cast<const __shim_type_info*>(exception_header->exceptionType);
762 if (adjustedPtr == 0 || excpType == 0)
763 {
764 // Something very bad happened
765 call_terminate(native_exception, unwind_exception);
766 }
767 if (catchType->can_catch(excpType, adjustedPtr))
768 {
769 // Found a matching handler. This is either search
770 // phase or forced unwinding.
771 assert(actions &
772 (_UA_SEARCH_PHASE | _UA_FORCE_UNWIND));
773 results.ttypeIndex = ttypeIndex;
774 results.actionRecord = actionRecord;
775 results.adjustedPtr = adjustedPtr;
776 results.reason = _URC_HANDLER_FOUND;
777 return;
778 }
779 }
780 // Scan next action ...
781 }
782 else if (ttypeIndex < 0)
783 {
784 // Found an exception specification.
785 if (actions & _UA_FORCE_UNWIND) {
786 // Skip if forced unwinding.
787 } else if (native_exception) {
788 // Does the exception spec catch this native exception?
789 __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1;
790 void* adjustedPtr = get_thrown_object_ptr(unwind_exception);
791 const __shim_type_info* excpType =
792 static_cast<const __shim_type_info*>(exception_header->exceptionType);
793 if (adjustedPtr == 0 || excpType == 0)
794 {
795 // Something very bad happened
796 call_terminate(native_exception, unwind_exception);
797 }
798 if (exception_spec_can_catch(ttypeIndex, classInfo,
799 ttypeEncoding, excpType,
800 adjustedPtr,
801 unwind_exception, base))
802 {
803 // Native exception caught by exception
804 // specification.
805 assert(actions & _UA_SEARCH_PHASE);
806 results.ttypeIndex = ttypeIndex;
807 results.actionRecord = actionRecord;
808 results.adjustedPtr = adjustedPtr;
809 results.reason = _URC_HANDLER_FOUND;
810 return;
811 }
812 } else {
813 // foreign exception caught by exception spec
814 results.ttypeIndex = ttypeIndex;
815 results.actionRecord = actionRecord;
816 results.adjustedPtr =
817 get_thrown_object_ptr(unwind_exception);
818 results.reason = _URC_HANDLER_FOUND;
819 return;
820 }
821 // Scan next action ...
822 } else {
823 hasCleanup = true;
824 }
825 const uint8_t* temp = action;
826 int64_t actionOffset = readSLEB128(&temp);
827 if (actionOffset == 0)
828 {
829 // End of action list. If this is phase 2 and we have found
830 // a cleanup (ttypeIndex=0), return _URC_HANDLER_FOUND;
831 // otherwise return _URC_CONTINUE_UNWIND.
832 results.reason = hasCleanup && actions & _UA_CLEANUP_PHASE
833 ? _URC_HANDLER_FOUND
834 : _URC_CONTINUE_UNWIND;
835 return;
836 }
837 // Go to next action
838 action += actionOffset;
839 } // there is no break out of this loop, only return
840 }
841#if !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__WASM_EXCEPTIONS__)
842 else if (ipOffset < start)
843 {
844 // There is no call site for this ip
845 // Something bad has happened. We should never get here.
846 // Possible stack corruption.
847 call_terminate(native_exception, unwind_exception);
848 }
849#endif // !__USING_SJLJ_EXCEPTIONS__ && !__WASM_EXCEPTIONS__
850 } // there might be some tricky cases which break out of this loop
851
852 // It is possible that no eh table entry specify how to handle
853 // this exception. By spec, terminate it immediately.
854 call_terminate(native_exception, unwind_exception);
855}
856
857// public API
858
859/*
860The personality function branches on actions like so:
861
862_UA_SEARCH_PHASE
863
864 If _UA_CLEANUP_PHASE or _UA_HANDLER_FRAME or _UA_FORCE_UNWIND there's
865 an error from above, return _URC_FATAL_PHASE1_ERROR.
866
867 Scan for anything that could stop unwinding:
868
869 1. A catch clause that will catch this exception
870 (will never catch foreign).
871 2. A catch (...) (will always catch foreign).
872 3. An exception spec that will catch this exception
873 (will always catch foreign).
874 If a handler is found
875 If not foreign
876 Save state in header
877 return _URC_HANDLER_FOUND
878 Else a handler not found
879 return _URC_CONTINUE_UNWIND
880
881_UA_CLEANUP_PHASE
882
883 If _UA_HANDLER_FRAME
884 If _UA_FORCE_UNWIND
885 How did this happen? return _URC_FATAL_PHASE2_ERROR
886 If foreign
887 Do _UA_SEARCH_PHASE to recover state
888 else
889 Recover state from header
890 Transfer control to landing pad. return _URC_INSTALL_CONTEXT
891
892 Else
893
894 This branch handles both normal C++ non-catching handlers (cleanups)
895 and forced unwinding.
896 Scan for anything that can not stop unwinding:
897
898 1. A cleanup.
899
900 If a cleanup is found
901 transfer control to it. return _URC_INSTALL_CONTEXT
902 Else a cleanup is not found: return _URC_CONTINUE_UNWIND
903*/
904
905#if !defined(_LIBCXXABI_ARM_EHABI)
906#ifdef __WASM_EXCEPTIONS__
907_Unwind_Reason_Code __gxx_personality_wasm0
908#elif defined(__SEH__) && !defined(__USING_SJLJ_EXCEPTIONS__)
909static _Unwind_Reason_Code __gxx_personality_imp
910#else
911_LIBCXXABI_FUNC_VIS _Unwind_Reason_Code
912#ifdef __USING_SJLJ_EXCEPTIONS__
913__gxx_personality_sj0
914#elif defined(__MVS__)
915__zos_cxx_personality_v2
916#else
917__gxx_personality_v0
918#endif
919#endif
920 (int version, _Unwind_Action actions, uint64_t exceptionClass,
921 _Unwind_Exception* unwind_exception, _Unwind_Context* context)
922{
923 if (version != 1 || unwind_exception == 0 || context == 0)
924 return _URC_FATAL_PHASE1_ERROR;
925
926 bool native_exception = (exceptionClass & get_vendor_and_language) ==
927 (kOurExceptionClass & get_vendor_and_language);
928 scan_results results;
929 // Process a catch handler for a native exception first.
930 if (actions == (_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME) &&
931 native_exception) {
932 // Reload the results from the phase 1 cache.
933 __cxa_exception* exception_header =
934 (__cxa_exception*)(unwind_exception + 1) - 1;
935 results.ttypeIndex = exception_header->handlerSwitchValue;
936 results.actionRecord = exception_header->actionRecord;
937 results.languageSpecificData = exception_header->languageSpecificData;
938 results.landingPad =
939 reinterpret_cast<uintptr_t>(exception_header->catchTemp);
940 results.adjustedPtr = exception_header->adjustedPtr;
941
942 // Jump to the handler.
943 set_registers(unwind_exception, context, results);
944 // Cache base for calculating the address of ttype in
945 // __cxa_call_unexpected.
946 if (results.ttypeIndex < 0) {
947#if defined(_AIX)
948 exception_header->catchTemp = (void *)_Unwind_GetDataRelBase(context);
949#else
950 exception_header->catchTemp = 0;
951#endif
952 }
953 return _URC_INSTALL_CONTEXT;
954 }
955
956 // In other cases we need to scan LSDA.
957 scan_eh_tab(results, actions, native_exception, unwind_exception, context);
958 if (results.reason == _URC_CONTINUE_UNWIND ||
959 results.reason == _URC_FATAL_PHASE1_ERROR)
960 return results.reason;
961
962 if (actions & _UA_SEARCH_PHASE)
963 {
964 // Phase 1 search: All we're looking for in phase 1 is a handler that
965 // halts unwinding
966 assert(results.reason == _URC_HANDLER_FOUND);
967 if (native_exception) {
968 // For a native exception, cache the LSDA result.
969 __cxa_exception* exc = (__cxa_exception*)(unwind_exception + 1) - 1;
970 exc->handlerSwitchValue = static_cast<int>(results.ttypeIndex);
971 exc->actionRecord = results.actionRecord;
972 exc->languageSpecificData = results.languageSpecificData;
973 exc->catchTemp = reinterpret_cast<void*>(results.landingPad);
974 exc->adjustedPtr = results.adjustedPtr;
975#ifdef __WASM_EXCEPTIONS__
976 // Wasm only uses a single phase (_UA_SEARCH_PHASE), so save the
977 // results here.
978 set_registers(unwind_exception, context, results);
979#endif
980 }
981 return _URC_HANDLER_FOUND;
982 }
983
984 assert(actions & _UA_CLEANUP_PHASE);
985 assert(results.reason == _URC_HANDLER_FOUND);
986 set_registers(unwind_exception, context, results);
987 // Cache base for calculating the address of ttype in __cxa_call_unexpected.
988 if (results.ttypeIndex < 0) {
989 __cxa_exception* exception_header =
990 (__cxa_exception*)(unwind_exception + 1) - 1;
991#if defined(_AIX)
992 exception_header->catchTemp = (void *)_Unwind_GetDataRelBase(context);
993#else
994 exception_header->catchTemp = 0;
995#endif
996 }
997 return _URC_INSTALL_CONTEXT;
998}
999
1000#if defined(__SEH__) && !defined(__USING_SJLJ_EXCEPTIONS__)
1001extern "C" _LIBCXXABI_FUNC_VIS EXCEPTION_DISPOSITION
1002__gxx_personality_seh0(PEXCEPTION_RECORD ms_exc, void *this_frame,
1003 PCONTEXT ms_orig_context, PDISPATCHER_CONTEXT ms_disp)
1004{
1005 return _GCC_specific_handler(ms_exc, this_frame, ms_orig_context, ms_disp,
1006 __gxx_personality_imp);
1007}
1008#endif
1009
1010#else
1011
1012extern "C" _Unwind_Reason_Code __gnu_unwind_frame(_Unwind_Exception*,
1013 _Unwind_Context*);
1014
1015// Helper function to unwind one frame.
1016// ARM EHABI 7.3 and 7.4: If the personality function returns _URC_CONTINUE_UNWIND, the
1017// personality routine should update the virtual register set (VRS) according to the
1018// corresponding frame unwinding instructions (ARM EHABI 9.3.)
1019static _Unwind_Reason_Code continue_unwind(_Unwind_Exception* unwind_exception,
1020 _Unwind_Context* context)
1021{
1022 switch (__gnu_unwind_frame(unwind_exception, context)) {
1023 case _URC_OK:
1024 return _URC_CONTINUE_UNWIND;
1025 case _URC_END_OF_STACK:
1026 return _URC_END_OF_STACK;
1027 default:
1028 return _URC_FAILURE;
1029 }
1030}
1031
1032// ARM register names
1033#if !defined(_LIBUNWIND_VERSION)
1034static const uint32_t REG_UCB = 12; // Register to save _Unwind_Control_Block
1035#endif
1036static const uint32_t REG_SP = 13;
1037
1038static void save_results_to_barrier_cache(_Unwind_Exception* unwind_exception,
1039 const scan_results& results)
1040{
1041 unwind_exception->barrier_cache.bitpattern[0] = (uint32_t)results.adjustedPtr;
1042 unwind_exception->barrier_cache.bitpattern[1] = (uint32_t)results.actionRecord;
1043 unwind_exception->barrier_cache.bitpattern[2] = (uint32_t)results.languageSpecificData;
1044 unwind_exception->barrier_cache.bitpattern[3] = (uint32_t)results.landingPad;
1045 unwind_exception->barrier_cache.bitpattern[4] = (uint32_t)results.ttypeIndex;
1046}
1047
1048static void load_results_from_barrier_cache(scan_results& results,
1049 const _Unwind_Exception* unwind_exception)
1050{
1051 results.adjustedPtr = (void*)unwind_exception->barrier_cache.bitpattern[0];
1052 results.actionRecord = (const uint8_t*)unwind_exception->barrier_cache.bitpattern[1];
1053 results.languageSpecificData = (const uint8_t*)unwind_exception->barrier_cache.bitpattern[2];
1054 results.landingPad = (uintptr_t)unwind_exception->barrier_cache.bitpattern[3];
1055 results.ttypeIndex = (int64_t)(int32_t)unwind_exception->barrier_cache.bitpattern[4];
1056}
1057
1058extern "C" _LIBCXXABI_FUNC_VIS _Unwind_Reason_Code
1059__gxx_personality_v0(_Unwind_State state,
1060 _Unwind_Exception* unwind_exception,
1061 _Unwind_Context* context)
1062{
1063 if (unwind_exception == 0 || context == 0)
1064 return _URC_FATAL_PHASE1_ERROR;
1065
1066 bool native_exception = __isOurExceptionClass(unwind_exception);
1067
1068#if !defined(_LIBUNWIND_VERSION)
1069 // Copy the address of _Unwind_Control_Block to r12 so that
1070 // _Unwind_GetLanguageSpecificData() and _Unwind_GetRegionStart() can
1071 // return correct address.
1072 _Unwind_SetGR(context, REG_UCB, reinterpret_cast<uint32_t>(unwind_exception));
1073#endif
1074
1075 // Check the undocumented force unwinding behavior
1076 bool is_force_unwinding = state & _US_FORCE_UNWIND;
1077 state &= ~_US_FORCE_UNWIND;
1078
1079 scan_results results;
1080 switch (state) {
1081 case _US_VIRTUAL_UNWIND_FRAME:
1082 if (is_force_unwinding)
1083 return continue_unwind(unwind_exception, context);
1084
1085 // Phase 1 search: All we're looking for in phase 1 is a handler that halts unwinding
1086 scan_eh_tab(results, _UA_SEARCH_PHASE, native_exception, unwind_exception, context);
1087 if (results.reason == _URC_HANDLER_FOUND)
1088 {
1089 unwind_exception->barrier_cache.sp = _Unwind_GetGR(context, REG_SP);
1090 if (native_exception)
1091 save_results_to_barrier_cache(unwind_exception, results);
1092 return _URC_HANDLER_FOUND;
1093 }
1094 // Did not find the catch handler
1095 if (results.reason == _URC_CONTINUE_UNWIND)
1096 return continue_unwind(unwind_exception, context);
1097 return results.reason;
1098
1099 case _US_UNWIND_FRAME_STARTING:
1100 // TODO: Support force unwinding in the phase 2 search.
1101 // NOTE: In order to call the cleanup functions, _Unwind_ForcedUnwind()
1102 // will call this personality function with (_US_FORCE_UNWIND |
1103 // _US_UNWIND_FRAME_STARTING).
1104
1105 // Phase 2 search
1106 if (unwind_exception->barrier_cache.sp == _Unwind_GetGR(context, REG_SP))
1107 {
1108 // Found a catching handler in phase 1
1109 if (native_exception)
1110 {
1111 // Load the result from the native exception barrier cache.
1112 load_results_from_barrier_cache(results, unwind_exception);
1113 results.reason = _URC_HANDLER_FOUND;
1114 }
1115 else
1116 {
1117 // Search for the catching handler again for the foreign exception.
1118 scan_eh_tab(results, static_cast<_Unwind_Action>(_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME),
1119 native_exception, unwind_exception, context);
1120 if (results.reason != _URC_HANDLER_FOUND) // phase1 search should guarantee to find one
1121 call_terminate(native_exception, unwind_exception);
1122 }
1123
1124 // Install the context for the catching handler
1125 set_registers(unwind_exception, context, results);
1126 return _URC_INSTALL_CONTEXT;
1127 }
1128
1129 // Either we didn't do a phase 1 search (due to forced unwinding), or
1130 // phase 1 reported no catching-handlers.
1131 // Search for a (non-catching) cleanup
1132 if (is_force_unwinding)
1133 scan_eh_tab(
1134 results,
1135 static_cast<_Unwind_Action>(_UA_CLEANUP_PHASE | _UA_FORCE_UNWIND),
1136 native_exception, unwind_exception, context);
1137 else
1138 scan_eh_tab(results, _UA_CLEANUP_PHASE, native_exception,
1139 unwind_exception, context);
1140 if (results.reason == _URC_HANDLER_FOUND)
1141 {
1142 // Found a non-catching handler
1143
1144 // ARM EHABI 8.4.2: Before we can jump to the cleanup handler, we have to setup some
1145 // internal data structures, so that __cxa_end_cleanup() can get unwind_exception from
1146 // __cxa_get_globals().
1147 __cxa_begin_cleanup(unwind_exception);
1148
1149 // Install the context for the cleanup handler
1150 set_registers(unwind_exception, context, results);
1151 return _URC_INSTALL_CONTEXT;
1152 }
1153
1154 // Did not find any handler
1155 if (results.reason == _URC_CONTINUE_UNWIND)
1156 return continue_unwind(unwind_exception, context);
1157 return results.reason;
1158
1159 case _US_UNWIND_FRAME_RESUME:
1160 return continue_unwind(unwind_exception, context);
1161 }
1162
1163 // We were called improperly: neither a phase 1 or phase 2 search
1164 return _URC_FATAL_PHASE1_ERROR;
1165}
1166#endif
1167
1168
1169__attribute__((noreturn))
1170_LIBCXXABI_FUNC_VIS void
1171__cxa_call_unexpected(void* arg)
1172{
1173 _Unwind_Exception* unwind_exception = static_cast<_Unwind_Exception*>(arg);
1174 if (unwind_exception == 0)
1175 call_terminate(false, unwind_exception);
1176 __cxa_begin_catch(unwind_exception);
1177 bool native_old_exception = __isOurExceptionClass(unwind_exception);
1178 std::unexpected_handler u_handler;
1179 std::terminate_handler t_handler;
1180 __cxa_exception* old_exception_header = 0;
1181 int64_t ttypeIndex;
1182 const uint8_t* lsda;
1183 uintptr_t base = 0;
1184
1185 if (native_old_exception)
1186 {
1187 old_exception_header = (__cxa_exception*)(unwind_exception+1) - 1;
1188 t_handler = old_exception_header->terminateHandler;
1189 u_handler = old_exception_header->unexpectedHandler;
1190 // If std::__unexpected(u_handler) rethrows the same exception,
1191 // these values get overwritten by the rethrow. So save them now:
1192#if defined(_LIBCXXABI_ARM_EHABI)
1193 ttypeIndex = (int64_t)(int32_t)unwind_exception->barrier_cache.bitpattern[4];
1194 lsda = (const uint8_t*)unwind_exception->barrier_cache.bitpattern[2];
1195#else
1196 ttypeIndex = old_exception_header->handlerSwitchValue;
1197 lsda = old_exception_header->languageSpecificData;
1198 base = (uintptr_t)old_exception_header->catchTemp;
1199#endif
1200 }
1201 else
1202 {
1203 t_handler = std::get_terminate();
1204 u_handler = std::get_unexpected();
1205 }
1206 try
1207 {
1208 std::__unexpected(u_handler);
1209 }
1210 catch (...)
1211 {
1212 // If the old exception is foreign, then all we can do is terminate.
1213 // We have no way to recover the needed old exception spec. There's
1214 // no way to pass that information here. And the personality routine
1215 // can't call us directly and do anything but terminate() if we throw
1216 // from here.
1217 if (native_old_exception)
1218 {
1219 // Have:
1220 // old_exception_header->languageSpecificData
1221 // old_exception_header->actionRecord
1222 // old_exception_header->catchTemp, base for calculating ttype
1223 // Need
1224 // const uint8_t* classInfo
1225 // uint8_t ttypeEncoding
1226 uint8_t lpStartEncoding = *lsda++;
1227 const uint8_t* lpStart =
1228 (const uint8_t*)readEncodedPointer(&lsda, lpStartEncoding, base);
1229 (void)lpStart; // purposefully unused. Just needed to increment lsda.
1230 uint8_t ttypeEncoding = *lsda++;
1231 if (ttypeEncoding == DW_EH_PE_omit)
1232 std::__terminate(t_handler);
1233 uintptr_t classInfoOffset = readULEB128(&lsda);
1234 const uint8_t* classInfo = lsda + classInfoOffset;
1235 // Is this new exception catchable by the exception spec at ttypeIndex?
1236 // The answer is obviously yes if the new and old exceptions are the same exception
1237 // If no
1238 // throw;
1239 __cxa_eh_globals* globals = __cxa_get_globals_fast();
1240 __cxa_exception* new_exception_header = globals->caughtExceptions;
1241 if (new_exception_header == 0)
1242 // This shouldn't be able to happen!
1243 std::__terminate(t_handler);
1244 bool native_new_exception = __isOurExceptionClass(&new_exception_header->unwindHeader);
1245 void* adjustedPtr;
1246 if (native_new_exception && (new_exception_header != old_exception_header))
1247 {
1248 const __shim_type_info* excpType =
1249 static_cast<const __shim_type_info*>(new_exception_header->exceptionType);
1250 adjustedPtr =
1251 __getExceptionClass(&new_exception_header->unwindHeader) == kOurDependentExceptionClass ?
1252 ((__cxa_dependent_exception*)new_exception_header)->primaryException :
1253 new_exception_header + 1;
1254 if (!exception_spec_can_catch(ttypeIndex, classInfo, ttypeEncoding,
1255 excpType, adjustedPtr,
1256 unwind_exception, base))
1257 {
1258 // We need to __cxa_end_catch, but for the old exception,
1259 // not the new one. This is a little tricky ...
1260 // Disguise new_exception_header as a rethrown exception, but
1261 // don't actually rethrow it. This means you can temporarily
1262 // end the catch clause enclosing new_exception_header without
1263 // __cxa_end_catch destroying new_exception_header.
1264 new_exception_header->handlerCount = -new_exception_header->handlerCount;
1265 globals->uncaughtExceptions += 1;
1266 // Call __cxa_end_catch for new_exception_header
1267 __cxa_end_catch();
1268 // Call __cxa_end_catch for old_exception_header
1269 __cxa_end_catch();
1270 // Renter this catch clause with new_exception_header
1271 __cxa_begin_catch(&new_exception_header->unwindHeader);
1272 // Rethrow new_exception_header
1273 throw;
1274 }
1275 }
1276 // Will a std::bad_exception be catchable by the exception spec at
1277 // ttypeIndex?
1278 // If no
1279 // throw std::bad_exception();
1280 const __shim_type_info* excpType =
1281 static_cast<const __shim_type_info*>(&typeid(std::bad_exception));
1282 std::bad_exception be;
1283 adjustedPtr = &be;
1284 if (!exception_spec_can_catch(ttypeIndex, classInfo, ttypeEncoding,
1285 excpType, adjustedPtr,
1286 unwind_exception, base))
1287 {
1288 // We need to __cxa_end_catch for both the old exception and the
1289 // new exception. Technically we should do it in that order.
1290 // But it is expedient to do it in the opposite order:
1291 // Call __cxa_end_catch for new_exception_header
1292 __cxa_end_catch();
1293 // Throw std::bad_exception will __cxa_end_catch for
1294 // old_exception_header
1295 throw be;
1296 }
1297 }
1298 }
1299 std::__terminate(t_handler);
1300}
1301
1302#if defined(_AIX)
1303// Personality routine for EH using the range table. Make it an alias of
1304// __gxx_personality_v0().
1305_LIBCXXABI_FUNC_VIS _Unwind_Reason_Code __xlcxx_personality_v1(
1306 int version, _Unwind_Action actions, uint64_t exceptionClass,
1307 _Unwind_Exception* unwind_exception, _Unwind_Context* context)
1308 __attribute__((__alias__("__gxx_personality_v0")));
1309#endif
1310
1311} // extern "C"
1312
1313} // __cxxabiv1
1314
1315#if defined(_AIX)
1316// Include implementation of the personality and helper functions for the
1317// state table based EH used by IBM legacy compilers xlC and xlclang++ on AIX.
1318# include "aix_state_tab_eh.inc"
1319#endif