UnwindCursor.hpp source code [libunwind/src/UnwindCursor.hpp]

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	// C++ interface to lower levels of libunwind
9	//===----------------------------------------------------------------------===//
10
11	#ifndef __UNWINDCURSOR_HPP__
12	#define __UNWINDCURSOR_HPP__
13
14	#include "shadow_stack_unwind.h"
15	#include <stdint.h>
16	#include <stdio.h>
17	#include <stdlib.h>
18	#include <unwind.h>
19
20	#ifdef _WIN32
21	#include <windows.h>
22	#include <ntverp.h>
23	#endif
24	#ifdef __APPLE__
25	#include <mach-o/dyld.h>
26	#endif
27	#ifdef _AIX
28	#include <dlfcn.h>
29	#include <sys/debug.h>
30	#include <sys/pseg.h>
31	#endif
32
33	#if defined(_LIBUNWIND_TARGET_LINUX) && \
34	(defined(_LIBUNWIND_TARGET_AARCH64) \|\| \
35	defined(_LIBUNWIND_TARGET_LOONGARCH) \|\| \
36	defined(_LIBUNWIND_TARGET_RISCV) \|\| defined(_LIBUNWIND_TARGET_S390X))
37	#include <errno.h>
38	#include <signal.h>
39	#include <sys/syscall.h>
40	#include <unistd.h>
41	#define _LIBUNWIND_CHECK_LINUX_SIGRETURN 1
42	#endif
43
44	#if defined(_LIBUNWIND_TARGET_HAIKU) && defined(_LIBUNWIND_TARGET_X86_64)
45	#include <OS.h>
46	#include <signal.h>
47	#define _LIBUNWIND_CHECK_HAIKU_SIGRETURN 1
48	#endif
49
50	#include "AddressSpace.hpp"
51	#include "CompactUnwinder.hpp"
52	#include "config.h"
53	#include "DwarfInstructions.hpp"
54	#include "EHHeaderParser.hpp"
55	#include "libunwind.h"
56	#include "libunwind_ext.h"
57	#include "Registers.hpp"
58	#include "RWMutex.hpp"
59	#include "Unwind-EHABI.h"
60
61	#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
62	// Provide a definition for the DISPATCHER_CONTEXT struct for old (Win7 and
63	// earlier) SDKs.
64	// MinGW-w64 has always provided this struct.
65	#if defined(_WIN32) && defined(_LIBUNWIND_TARGET_X86_64) && \
66	!defined(__MINGW32__) && VER_PRODUCTBUILD < 8000
67	struct _DISPATCHER_CONTEXT {
68	ULONG64 ControlPc;
69	ULONG64 ImageBase;
70	PRUNTIME_FUNCTION FunctionEntry;
71	ULONG64 EstablisherFrame;
72	ULONG64 TargetIp;
73	PCONTEXT ContextRecord;
74	PEXCEPTION_ROUTINE LanguageHandler;
75	PVOID HandlerData;
76	PUNWIND_HISTORY_TABLE HistoryTable;
77	ULONG ScopeIndex;
78	ULONG Fill0;
79	};
80	#endif
81
82	struct UNWIND_INFO {
83	uint8_t Version : `3`;
84	uint8_t Flags : `5`;
85	uint8_t SizeOfProlog;
86	uint8_t CountOfCodes;
87	uint8_t FrameRegister : `4`;
88	uint8_t FrameOffset : `4`;
89	uint16_t UnwindCodes[`2`];
90	};
91
92	#pragma clang diagnostic push
93	#pragma clang diagnostic ignored "-Wgnu-anonymous-struct"
94	union UNWIND_INFO_ARM {
95	DWORD HeaderData;
96	struct {
97	DWORD FunctionLength : `18`;
98	DWORD Version : `2`;
99	DWORD ExceptionDataPresent : `1`;
100	DWORD EpilogInHeader : `1`;
101	DWORD FunctionFragment : `1`;
102	DWORD EpilogCount : `5`;
103	DWORD CodeWords : `4`;
104	};
105	};
106	#pragma clang diagnostic pop
107
108	extern "C" _Unwind_Reason_Code __libunwind_seh_personality(
109	int, _Unwind_Action, uint64_t, _Unwind_Exception *,
110	struct _Unwind_Context *);
111
112	#endif
113
114	namespace libunwind {
115
116	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
117	/// Cache of recently found FDEs.
118	template <typename A>
119	class _LIBUNWIND_HIDDEN DwarfFDECache {
120	typedef typename A::pint_t pint_t;
121	public:
122	static constexpr pint_t kSearchAll = static_cast<pint_t>(-`1`);
123	static pint_t findFDE(pint_t mh, pint_t pc);
124	static void add(pint_t mh, pint_t ip_start, pint_t ip_end, pint_t fde);
125	static void removeAllIn(pint_t mh);
126	static void iterateCacheEntries(void (*func)(unw_word_t ip_start,
127	unw_word_t ip_end,
128	unw_word_t fde, unw_word_t mh));
129
130	private:
131
132	struct entry {
133	pint_t mh;
134	pint_t ip_start;
135	pint_t ip_end;
136	pint_t fde;
137	};
138
139	// These fields are all static to avoid needing an initializer.
140	// There is only one instance of this class per process.
141	static RWMutex _lock;
142	#ifdef __APPLE__
143	static void dyldUnloadHook(const struct mach_header *mh, intptr_t slide);
144	static bool _registeredForDyldUnloads;
145	#endif
146	static entry *_buffer;
147	static entry *_bufferUsed;
148	static entry *_bufferEnd;
149	static entry _initialBuffer[`64`];
150	};
151
152	template <typename A>
153	typename DwarfFDECache<A>::entry *
154	DwarfFDECache<A>::_buffer = _initialBuffer;
155
156	template <typename A>
157	typename DwarfFDECache<A>::entry *
158	DwarfFDECache<A>::_bufferUsed = _initialBuffer;
159
160	template <typename A>
161	typename DwarfFDECache<A>::entry *
162	DwarfFDECache<A>::_bufferEnd = &_initialBuffer[`64`];
163
164	template <typename A>
165	typename DwarfFDECache<A>::entry DwarfFDECache<A>::_initialBuffer[`64`];
166
167	template <typename A>
168	RWMutex DwarfFDECache<A>::_lock;
169
170	#ifdef __APPLE__
171	template <typename A>
172	bool DwarfFDECache<A>::_registeredForDyldUnloads = false;
173	#endif
174
175	template <typename A>
176	typename A::pint_t DwarfFDECache<A>::findFDE(pint_t mh, pint_t pc) {
177	pint_t result = `0`;
178	_LIBUNWIND_LOG_IF_FALSE(_lock.lock_shared());
179	for (entry *p = _buffer; p < _bufferUsed; ++p) {
180	if ((mh == p->mh) \|\| (mh == kSearchAll)) {
181	if ((p->ip_start <= pc) && (pc < p->ip_end)) {
182	result = p->fde;
183	break;
184	}
185	}
186	}
187	_LIBUNWIND_LOG_IF_FALSE(_lock.unlock_shared());
188	return result;
189	}
190
191	template <typename A>
192	void DwarfFDECache<A>::add(pint_t mh, pint_t ip_start, pint_t ip_end,
193	pint_t fde) {
194	#if !defined(_LIBUNWIND_NO_HEAP)
195	_LIBUNWIND_LOG_IF_FALSE(_lock.lock());
196	if (_bufferUsed >= _bufferEnd) {
197	size_t oldSize = (size_t)(_bufferEnd - _buffer);
198	size_t newSize = oldSize * `4`;
199	// Can't use operator new (we are below it).
200	entry newBuffer = (entry )malloc(size: newSize * sizeof(entry));
201	memcpy(newBuffer, _buffer, oldSize * sizeof(entry));
202	if (_buffer != _initialBuffer)
203	free(_buffer);
204	_buffer = newBuffer;
205	_bufferUsed = &newBuffer[oldSize];
206	_bufferEnd = &newBuffer[newSize];
207	}
208	_bufferUsed->mh = mh;
209	_bufferUsed->ip_start = ip_start;
210	_bufferUsed->ip_end = ip_end;
211	_bufferUsed->fde = fde;
212	++_bufferUsed;
213	#ifdef __APPLE__
214	if (!_registeredForDyldUnloads) {
215	_dyld_register_func_for_remove_image(&dyldUnloadHook);
216	_registeredForDyldUnloads = true;
217	}
218	#endif
219	_LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
220	#endif
221	}
222
223	template <typename A>
224	void DwarfFDECache<A>::removeAllIn(pint_t mh) {
225	_LIBUNWIND_LOG_IF_FALSE(_lock.lock());
226	entry *d = _buffer;
227	for (const entry *s = _buffer; s < _bufferUsed; ++s) {
228	if (s->mh != mh) {
229	if (d != s)
230	d = s;
231	++d;
232	}
233	}
234	_bufferUsed = d;
235	_LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
236	}
237
238	#ifdef __APPLE__
239	template <typename A>
240	void DwarfFDECache<A>::dyldUnloadHook(const struct mach_header *mh, intptr_t ) {
241	removeAllIn((pint_t) mh);
242	}
243	#endif
244
245	template <typename A>
246	void DwarfFDECache<A>::iterateCacheEntries(void (*func)(
247	unw_word_t ip_start, unw_word_t ip_end, unw_word_t fde, unw_word_t mh)) {
248	_LIBUNWIND_LOG_IF_FALSE(_lock.lock());
249	for (entry *p = _buffer; p < _bufferUsed; ++p) {
250	(*func)(p->ip_start, p->ip_end, p->fde, p->mh);
251	}
252	_LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
253	}
254	#endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
255
256	#define arrayoffsetof(type, index, field) \
257	(sizeof(type) * (index) + offsetof(type, field))
258
259	#if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
260	template <typename A> class UnwindSectionHeader {
261	public:
262	UnwindSectionHeader(A &addressSpace, typename A::pint_t addr)
263	: _addressSpace(addressSpace), _addr(addr) {}
264
265	uint32_t version() const {
266	return _addressSpace.get32(_addr +
267	offsetof(unwind_info_section_header, version));
268	}
269	uint32_t commonEncodingsArraySectionOffset() const {
270	return _addressSpace.get32(_addr +
271	offsetof(unwind_info_section_header,
272	commonEncodingsArraySectionOffset));
273	}
274	uint32_t commonEncodingsArrayCount() const {
275	return _addressSpace.get32(_addr + offsetof(unwind_info_section_header,
276	commonEncodingsArrayCount));
277	}
278	uint32_t personalityArraySectionOffset() const {
279	return _addressSpace.get32(_addr + offsetof(unwind_info_section_header,
280	personalityArraySectionOffset));
281	}
282	uint32_t personalityArrayCount() const {
283	return _addressSpace.get32(
284	_addr + offsetof(unwind_info_section_header, personalityArrayCount));
285	}
286	uint32_t indexSectionOffset() const {
287	return _addressSpace.get32(
288	_addr + offsetof(unwind_info_section_header, indexSectionOffset));
289	}
290	uint32_t indexCount() const {
291	return _addressSpace.get32(
292	_addr + offsetof(unwind_info_section_header, indexCount));
293	}
294
295	private:
296	A &_addressSpace;
297	typename A::pint_t _addr;
298	};
299
300	template <typename A> class UnwindSectionIndexArray {
301	public:
302	UnwindSectionIndexArray(A &addressSpace, typename A::pint_t addr)
303	: _addressSpace(addressSpace), _addr(addr) {}
304
305	uint32_t functionOffset(uint32_t index) const {
306	return _addressSpace.get32(
307	_addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
308	functionOffset));
309	}
310	uint32_t secondLevelPagesSectionOffset(uint32_t index) const {
311	return _addressSpace.get32(
312	_addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
313	secondLevelPagesSectionOffset));
314	}
315	uint32_t lsdaIndexArraySectionOffset(uint32_t index) const {
316	return _addressSpace.get32(
317	_addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
318	lsdaIndexArraySectionOffset));
319	}
320
321	private:
322	A &_addressSpace;
323	typename A::pint_t _addr;
324	};
325
326	template <typename A> class UnwindSectionRegularPageHeader {
327	public:
328	UnwindSectionRegularPageHeader(A &addressSpace, typename A::pint_t addr)
329	: _addressSpace(addressSpace), _addr(addr) {}
330
331	uint32_t kind() const {
332	return _addressSpace.get32(
333	_addr + offsetof(unwind_info_regular_second_level_page_header, kind));
334	}
335	uint16_t entryPageOffset() const {
336	return _addressSpace.get16(
337	_addr + offsetof(unwind_info_regular_second_level_page_header,
338	entryPageOffset));
339	}
340	uint16_t entryCount() const {
341	return _addressSpace.get16(
342	_addr +
343	offsetof(unwind_info_regular_second_level_page_header, entryCount));
344	}
345
346	private:
347	A &_addressSpace;
348	typename A::pint_t _addr;
349	};
350
351	template <typename A> class UnwindSectionRegularArray {
352	public:
353	UnwindSectionRegularArray(A &addressSpace, typename A::pint_t addr)
354	: _addressSpace(addressSpace), _addr(addr) {}
355
356	uint32_t functionOffset(uint32_t index) const {
357	return _addressSpace.get32(
358	_addr + arrayoffsetof(unwind_info_regular_second_level_entry, index,
359	functionOffset));
360	}
361	uint32_t encoding(uint32_t index) const {
362	return _addressSpace.get32(
363	_addr +
364	arrayoffsetof(unwind_info_regular_second_level_entry, index, encoding));
365	}
366
367	private:
368	A &_addressSpace;
369	typename A::pint_t _addr;
370	};
371
372	template <typename A> class UnwindSectionCompressedPageHeader {
373	public:
374	UnwindSectionCompressedPageHeader(A &addressSpace, typename A::pint_t addr)
375	: _addressSpace(addressSpace), _addr(addr) {}
376
377	uint32_t kind() const {
378	return _addressSpace.get32(
379	_addr +
380	offsetof(unwind_info_compressed_second_level_page_header, kind));
381	}
382	uint16_t entryPageOffset() const {
383	return _addressSpace.get16(
384	_addr + offsetof(unwind_info_compressed_second_level_page_header,
385	entryPageOffset));
386	}
387	uint16_t entryCount() const {
388	return _addressSpace.get16(
389	_addr +
390	offsetof(unwind_info_compressed_second_level_page_header, entryCount));
391	}
392	uint16_t encodingsPageOffset() const {
393	return _addressSpace.get16(
394	_addr + offsetof(unwind_info_compressed_second_level_page_header,
395	encodingsPageOffset));
396	}
397	uint16_t encodingsCount() const {
398	return _addressSpace.get16(
399	_addr + offsetof(unwind_info_compressed_second_level_page_header,
400	encodingsCount));
401	}
402
403	private:
404	A &_addressSpace;
405	typename A::pint_t _addr;
406	};
407
408	template <typename A> class UnwindSectionCompressedArray {
409	public:
410	UnwindSectionCompressedArray(A &addressSpace, typename A::pint_t addr)
411	: _addressSpace(addressSpace), _addr(addr) {}
412
413	uint32_t functionOffset(uint32_t index) const {
414	return UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET(
415	_addressSpace.get32(_addr + index * sizeof(uint32_t)));
416	}
417	uint16_t encodingIndex(uint32_t index) const {
418	return UNWIND_INFO_COMPRESSED_ENTRY_ENCODING_INDEX(
419	_addressSpace.get32(_addr + index * sizeof(uint32_t)));
420	}
421
422	private:
423	A &_addressSpace;
424	typename A::pint_t _addr;
425	};
426
427	template <typename A> class UnwindSectionLsdaArray {
428	public:
429	UnwindSectionLsdaArray(A &addressSpace, typename A::pint_t addr)
430	: _addressSpace(addressSpace), _addr(addr) {}
431
432	uint32_t functionOffset(uint32_t index) const {
433	return _addressSpace.get32(
434	_addr + arrayoffsetof(unwind_info_section_header_lsda_index_entry,
435	index, functionOffset));
436	}
437	uint32_t lsdaOffset(uint32_t index) const {
438	return _addressSpace.get32(
439	_addr + arrayoffsetof(unwind_info_section_header_lsda_index_entry,
440	index, lsdaOffset));
441	}
442
443	private:
444	A &_addressSpace;
445	typename A::pint_t _addr;
446	};
447	#endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
448
449	class _LIBUNWIND_HIDDEN AbstractUnwindCursor {
450	public:
451	// NOTE: provide a class specific placement deallocation function (S5.3.4 p20)
452	// This avoids an unnecessary dependency to libc++abi.
453	void operator delete(void *, size_t) {}
454
455	virtual ~AbstractUnwindCursor() {}
456	virtual bool validReg(int) { _LIBUNWIND_ABORT("validReg not implemented"); }
457	virtual unw_word_t getReg(int) { _LIBUNWIND_ABORT("getReg not implemented"); }
458	virtual void setReg(int, unw_word_t) {
459	_LIBUNWIND_ABORT("setReg not implemented");
460	}
461	virtual bool validFloatReg(int) {
462	_LIBUNWIND_ABORT("validFloatReg not implemented");
463	}
464	virtual unw_fpreg_t getFloatReg(int) {
465	_LIBUNWIND_ABORT("getFloatReg not implemented");
466	}
467	virtual void setFloatReg(int, unw_fpreg_t) {
468	_LIBUNWIND_ABORT("setFloatReg not implemented");
469	}
470	virtual int step(bool = false) { _LIBUNWIND_ABORT("step not implemented"); }
471	virtual void getInfo(unw_proc_info_t *) {
472	_LIBUNWIND_ABORT("getInfo not implemented");
473	}
474	virtual void jumpto() { _LIBUNWIND_ABORT("jumpto not implemented"); }
475	virtual bool isSignalFrame() {
476	_LIBUNWIND_ABORT("isSignalFrame not implemented");
477	}
478	virtual bool getFunctionName(char , size_t, unw_word_t ) {
479	_LIBUNWIND_ABORT("getFunctionName not implemented");
480	}
481	virtual void setInfoBasedOnIPRegister(bool = false) {
482	_LIBUNWIND_ABORT("setInfoBasedOnIPRegister not implemented");
483	}
484	virtual const char getRegisterName(int*) {
485	_LIBUNWIND_ABORT("getRegisterName not implemented");
486	}
487	#ifdef __arm__
488	virtual void saveVFPAsX() { _LIBUNWIND_ABORT("saveVFPAsX not implemented"); }
489	#endif
490
491	#ifdef _AIX
492	virtual uintptr_t getDataRelBase() {
493	_LIBUNWIND_ABORT("getDataRelBase not implemented");
494	}
495	#endif
496
497	#if defined(_LIBUNWIND_USE_CET) \|\| defined(_LIBUNWIND_USE_GCS)
498	virtual void *get_registers() {
499	_LIBUNWIND_ABORT("get_registers not implemented");
500	}
501	#endif
502	};
503
504	#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) && defined(_WIN32)
505
506	/// \c UnwindCursor contains all state (including all register values) during
507	/// an unwind. This is normally stack-allocated inside a unw_cursor_t.
508	template <typename A, typename R>
509	class UnwindCursor : public AbstractUnwindCursor {
510	typedef typename A::pint_t pint_t;
511	public:
512	UnwindCursor(unw_context_t *context, A &as);
513	UnwindCursor(CONTEXT *context, A &as);
514	UnwindCursor(A &as, void *threadArg);
515	virtual ~UnwindCursor() {}
516	virtual bool validReg(int);
517	virtual unw_word_t getReg(int);
518	virtual void setReg(int, unw_word_t);
519	virtual bool validFloatReg(int);
520	virtual unw_fpreg_t getFloatReg(int);
521	virtual void setFloatReg(int, unw_fpreg_t);
522	virtual int step(bool = false);
523	virtual void getInfo(unw_proc_info_t *);
524	virtual void jumpto();
525	virtual bool isSignalFrame();
526	virtual bool getFunctionName(char buf, size_t len, unw_word_t off);
527	virtual void setInfoBasedOnIPRegister(bool isReturnAddress = false);
528	virtual const char getRegisterName(int* num);
529	#ifdef __arm__
530	virtual void saveVFPAsX();
531	#endif
532
533	DISPATCHER_CONTEXT getDispatcherContext() { return* &_dispContext; }
534	void setDispatcherContext(DISPATCHER_CONTEXT *disp) {
535	_dispContext = *disp;
536	_info.lsda = reinterpret_cast<unw_word_t>(_dispContext.HandlerData);
537	if (_dispContext.LanguageHandler) {
538	_info.handler = reinterpret_cast<unw_word_t>(__libunwind_seh_personality);
539	} else
540	_info.handler = `0`;
541	}
542
543	// libunwind does not and should not depend on C++ library which means that we
544	// need our own definition of inline placement new.
545	static void *operator new(size_t, UnwindCursor<A, R> p) { return* p; }
546
547	private:
548
549	pint_t getLastPC() const { return _dispContext.ControlPc; }
550	void setLastPC(pint_t pc) { _dispContext.ControlPc = pc; }
551	RUNTIME_FUNCTION lookUpSEHUnwindInfo(pint_t pc, pint_t base) {
552	#ifdef __arm__
553	// Remove the thumb bit; FunctionEntry ranges don't include the thumb bit.
554	pc &= ~`1U`;
555	#endif
556	// If pc points exactly at the end of the range, we might resolve the
557	// next function instead. Decrement pc by 1 to fit inside the current
558	// function.
559	pc -= `1`;
560	_dispContext.FunctionEntry = RtlLookupFunctionEntry(pc,
561	&_dispContext.ImageBase,
562	_dispContext.HistoryTable);
563	*base = _dispContext.ImageBase;
564	return _dispContext.FunctionEntry;
565	}
566	bool getInfoFromSEH(pint_t pc);
567	int stepWithSEHData() {
568	_dispContext.LanguageHandler = RtlVirtualUnwind(UNW_FLAG_UHANDLER,
569	_dispContext.ImageBase,
570	_dispContext.ControlPc,
571	_dispContext.FunctionEntry,
572	_dispContext.ContextRecord,
573	&_dispContext.HandlerData,
574	&_dispContext.EstablisherFrame,
575	NULL);
576	// Update some fields of the unwind info now, since we have them.
577	_info.lsda = reinterpret_cast<unw_word_t>(_dispContext.HandlerData);
578	if (_dispContext.LanguageHandler) {
579	_info.handler = reinterpret_cast<unw_word_t>(__libunwind_seh_personality);
580	} else
581	_info.handler = `0`;
582	return UNW_STEP_SUCCESS;
583	}
584
585	A &_addressSpace;
586	unw_proc_info_t _info;
587	DISPATCHER_CONTEXT _dispContext;
588	CONTEXT _msContext;
589	UNWIND_HISTORY_TABLE _histTable;
590	bool _unwindInfoMissing;
591	};
592
593
594	template <typename A, typename R>
595	UnwindCursor<A, R>::UnwindCursor(unw_context_t *context, A &as)
596	: _addressSpace(as), _unwindInfoMissing(false) {
597	static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
598	"UnwindCursor<> does not fit in unw_cursor_t");
599	static_assert((alignof(UnwindCursor<A, R>) <= alignof(unw_cursor_t)),
600	"UnwindCursor<> requires more alignment than unw_cursor_t");
601	memset(&_info, `0`, sizeof(_info));
602	memset(&_histTable, `0`, sizeof(_histTable));
603	memset(&_dispContext, `0`, sizeof(_dispContext));
604	_dispContext.ContextRecord = &_msContext;
605	_dispContext.HistoryTable = &_histTable;
606	// Initialize MS context from ours.
607	R r(context);
608	RtlCaptureContext(&_msContext);
609	_msContext.ContextFlags = CONTEXT_CONTROL\|CONTEXT_INTEGER\|CONTEXT_FLOATING_POINT;
610	#if defined(_LIBUNWIND_TARGET_X86_64)
611	_msContext.Rax = r.getRegister(UNW_X86_64_RAX);
612	_msContext.Rcx = r.getRegister(UNW_X86_64_RCX);
613	_msContext.Rdx = r.getRegister(UNW_X86_64_RDX);
614	_msContext.Rbx = r.getRegister(UNW_X86_64_RBX);
615	_msContext.Rsp = r.getRegister(UNW_X86_64_RSP);
616	_msContext.Rbp = r.getRegister(UNW_X86_64_RBP);
617	_msContext.Rsi = r.getRegister(UNW_X86_64_RSI);
618	_msContext.Rdi = r.getRegister(UNW_X86_64_RDI);
619	_msContext.R8 = r.getRegister(UNW_X86_64_R8);
620	_msContext.R9 = r.getRegister(UNW_X86_64_R9);
621	_msContext.R10 = r.getRegister(UNW_X86_64_R10);
622	_msContext.R11 = r.getRegister(UNW_X86_64_R11);
623	_msContext.R12 = r.getRegister(UNW_X86_64_R12);
624	_msContext.R13 = r.getRegister(UNW_X86_64_R13);
625	_msContext.R14 = r.getRegister(UNW_X86_64_R14);
626	_msContext.R15 = r.getRegister(UNW_X86_64_R15);
627	_msContext.Rip = r.getRegister(UNW_REG_IP);
628	union {
629	v128 v;
630	M128A m;
631	} t;
632	t.v = r.getVectorRegister(UNW_X86_64_XMM0);
633	_msContext.Xmm0 = t.m;
634	t.v = r.getVectorRegister(UNW_X86_64_XMM1);
635	_msContext.Xmm1 = t.m;
636	t.v = r.getVectorRegister(UNW_X86_64_XMM2);
637	_msContext.Xmm2 = t.m;
638	t.v = r.getVectorRegister(UNW_X86_64_XMM3);
639	_msContext.Xmm3 = t.m;
640	t.v = r.getVectorRegister(UNW_X86_64_XMM4);
641	_msContext.Xmm4 = t.m;
642	t.v = r.getVectorRegister(UNW_X86_64_XMM5);
643	_msContext.Xmm5 = t.m;
644	t.v = r.getVectorRegister(UNW_X86_64_XMM6);
645	_msContext.Xmm6 = t.m;
646	t.v = r.getVectorRegister(UNW_X86_64_XMM7);
647	_msContext.Xmm7 = t.m;
648	t.v = r.getVectorRegister(UNW_X86_64_XMM8);
649	_msContext.Xmm8 = t.m;
650	t.v = r.getVectorRegister(UNW_X86_64_XMM9);
651	_msContext.Xmm9 = t.m;
652	t.v = r.getVectorRegister(UNW_X86_64_XMM10);
653	_msContext.Xmm10 = t.m;
654	t.v = r.getVectorRegister(UNW_X86_64_XMM11);
655	_msContext.Xmm11 = t.m;
656	t.v = r.getVectorRegister(UNW_X86_64_XMM12);
657	_msContext.Xmm12 = t.m;
658	t.v = r.getVectorRegister(UNW_X86_64_XMM13);
659	_msContext.Xmm13 = t.m;
660	t.v = r.getVectorRegister(UNW_X86_64_XMM14);
661	_msContext.Xmm14 = t.m;
662	t.v = r.getVectorRegister(UNW_X86_64_XMM15);
663	_msContext.Xmm15 = t.m;
664	#elif defined(_LIBUNWIND_TARGET_ARM)
665	_msContext.R0 = r.getRegister(UNW_ARM_R0);
666	_msContext.R1 = r.getRegister(UNW_ARM_R1);
667	_msContext.R2 = r.getRegister(UNW_ARM_R2);
668	_msContext.R3 = r.getRegister(UNW_ARM_R3);
669	_msContext.R4 = r.getRegister(UNW_ARM_R4);
670	_msContext.R5 = r.getRegister(UNW_ARM_R5);
671	_msContext.R6 = r.getRegister(UNW_ARM_R6);
672	_msContext.R7 = r.getRegister(UNW_ARM_R7);
673	_msContext.R8 = r.getRegister(UNW_ARM_R8);
674	_msContext.R9 = r.getRegister(UNW_ARM_R9);
675	_msContext.R10 = r.getRegister(UNW_ARM_R10);
676	_msContext.R11 = r.getRegister(UNW_ARM_R11);
677	_msContext.R12 = r.getRegister(UNW_ARM_R12);
678	_msContext.Sp = r.getRegister(UNW_ARM_SP);
679	_msContext.Lr = r.getRegister(UNW_ARM_LR);
680	_msContext.Pc = r.getRegister(UNW_ARM_IP);
681	for (int i = UNW_ARM_D0; i <= UNW_ARM_D31; ++i) {
682	union {
683	uint64_t w;
684	double d;
685	} d;
686	d.d = r.getFloatRegister(i);
687	_msContext.D[i - UNW_ARM_D0] = d.w;
688	}
689	#elif defined(_LIBUNWIND_TARGET_AARCH64)
690	for (int i = UNW_AARCH64_X0; i <= UNW_ARM64_X30; ++i)
691	_msContext.X[i - UNW_AARCH64_X0] = r.getRegister(i);
692	_msContext.Sp = r.getRegister(UNW_REG_SP);
693	_msContext.Pc = r.getRegister(UNW_REG_IP);
694	for (int i = UNW_AARCH64_V0; i <= UNW_ARM64_D31; ++i)
695	_msContext.V[i - UNW_AARCH64_V0].D[`0`] = r.getFloatRegister(i);
696	#endif
697	}
698
699	template <typename A, typename R>
700	UnwindCursor<A, R>::UnwindCursor(CONTEXT *context, A &as)
701	: _addressSpace(as), _unwindInfoMissing(false) {
702	static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
703	"UnwindCursor<> does not fit in unw_cursor_t");
704	memset(&_info, `0`, sizeof(_info));
705	memset(&_histTable, `0`, sizeof(_histTable));
706	memset(&_dispContext, `0`, sizeof(_dispContext));
707	_dispContext.ContextRecord = &_msContext;
708	_dispContext.HistoryTable = &_histTable;
709	_msContext = *context;
710	}
711
712
713	template <typename A, typename R>
714	bool UnwindCursor<A, R>::validReg(int regNum) {
715	if (regNum == UNW_REG_IP \|\| regNum == UNW_REG_SP) return true;
716	#if defined(_LIBUNWIND_TARGET_X86_64)
717	if (regNum >= UNW_X86_64_RAX && regNum <= UNW_X86_64_RIP) return true;
718	#elif defined(_LIBUNWIND_TARGET_ARM)
719	if ((regNum >= UNW_ARM_R0 && regNum <= UNW_ARM_R15) \|\|
720	regNum == UNW_ARM_RA_AUTH_CODE)
721	return true;
722	#elif defined(_LIBUNWIND_TARGET_AARCH64)
723	if (regNum >= UNW_AARCH64_X0 && regNum <= UNW_ARM64_X30) return true;
724	#endif
725	return false;
726	}
727
728	template <typename A, typename R>
729	unw_word_t UnwindCursor<A, R>::getReg(int regNum) {
730	switch (regNum) {
731	#if defined(_LIBUNWIND_TARGET_X86_64)
732	case UNW_X86_64_RIP:
733	case UNW_REG_IP: return _msContext.Rip;
734	case UNW_X86_64_RAX: return _msContext.Rax;
735	case UNW_X86_64_RDX: return _msContext.Rdx;
736	case UNW_X86_64_RCX: return _msContext.Rcx;
737	case UNW_X86_64_RBX: return _msContext.Rbx;
738	case UNW_REG_SP:
739	case UNW_X86_64_RSP: return _msContext.Rsp;
740	case UNW_X86_64_RBP: return _msContext.Rbp;
741	case UNW_X86_64_RSI: return _msContext.Rsi;
742	case UNW_X86_64_RDI: return _msContext.Rdi;
743	case UNW_X86_64_R8: return _msContext.R8;
744	case UNW_X86_64_R9: return _msContext.R9;
745	case UNW_X86_64_R10: return _msContext.R10;
746	case UNW_X86_64_R11: return _msContext.R11;
747	case UNW_X86_64_R12: return _msContext.R12;
748	case UNW_X86_64_R13: return _msContext.R13;
749	case UNW_X86_64_R14: return _msContext.R14;
750	case UNW_X86_64_R15: return _msContext.R15;
751	#elif defined(_LIBUNWIND_TARGET_ARM)
752	case UNW_ARM_R0: return _msContext.R0;
753	case UNW_ARM_R1: return _msContext.R1;
754	case UNW_ARM_R2: return _msContext.R2;
755	case UNW_ARM_R3: return _msContext.R3;
756	case UNW_ARM_R4: return _msContext.R4;
757	case UNW_ARM_R5: return _msContext.R5;
758	case UNW_ARM_R6: return _msContext.R6;
759	case UNW_ARM_R7: return _msContext.R7;
760	case UNW_ARM_R8: return _msContext.R8;
761	case UNW_ARM_R9: return _msContext.R9;
762	case UNW_ARM_R10: return _msContext.R10;
763	case UNW_ARM_R11: return _msContext.R11;
764	case UNW_ARM_R12: return _msContext.R12;
765	case UNW_REG_SP:
766	case UNW_ARM_SP: return _msContext.Sp;
767	case UNW_ARM_LR: return _msContext.Lr;
768	case UNW_REG_IP:
769	case UNW_ARM_IP: return _msContext.Pc;
770	#elif defined(_LIBUNWIND_TARGET_AARCH64)
771	case UNW_REG_SP: return _msContext.Sp;
772	case UNW_REG_IP: return _msContext.Pc;
773	default: return _msContext.X[regNum - UNW_AARCH64_X0];
774	#endif
775	}
776	_LIBUNWIND_ABORT("unsupported register");
777	}
778
779	template <typename A, typename R>
780	void UnwindCursor<A, R>::setReg(int regNum, unw_word_t value) {
781	switch (regNum) {
782	#if defined(_LIBUNWIND_TARGET_X86_64)
783	case UNW_X86_64_RIP:
784	case UNW_REG_IP: _msContext.Rip = value; break;
785	case UNW_X86_64_RAX: _msContext.Rax = value; break;
786	case UNW_X86_64_RDX: _msContext.Rdx = value; break;
787	case UNW_X86_64_RCX: _msContext.Rcx = value; break;
788	case UNW_X86_64_RBX: _msContext.Rbx = value; break;
789	case UNW_REG_SP:
790	case UNW_X86_64_RSP: _msContext.Rsp = value; break;
791	case UNW_X86_64_RBP: _msContext.Rbp = value; break;
792	case UNW_X86_64_RSI: _msContext.Rsi = value; break;
793	case UNW_X86_64_RDI: _msContext.Rdi = value; break;
794	case UNW_X86_64_R8: _msContext.R8 = value; break;
795	case UNW_X86_64_R9: _msContext.R9 = value; break;
796	case UNW_X86_64_R10: _msContext.R10 = value; break;
797	case UNW_X86_64_R11: _msContext.R11 = value; break;
798	case UNW_X86_64_R12: _msContext.R12 = value; break;
799	case UNW_X86_64_R13: _msContext.R13 = value; break;
800	case UNW_X86_64_R14: _msContext.R14 = value; break;
801	case UNW_X86_64_R15: _msContext.R15 = value; break;
802	#elif defined(_LIBUNWIND_TARGET_ARM)
803	case UNW_ARM_R0: _msContext.R0 = value; break;
804	case UNW_ARM_R1: _msContext.R1 = value; break;
805	case UNW_ARM_R2: _msContext.R2 = value; break;
806	case UNW_ARM_R3: _msContext.R3 = value; break;
807	case UNW_ARM_R4: _msContext.R4 = value; break;
808	case UNW_ARM_R5: _msContext.R5 = value; break;
809	case UNW_ARM_R6: _msContext.R6 = value; break;
810	case UNW_ARM_R7: _msContext.R7 = value; break;
811	case UNW_ARM_R8: _msContext.R8 = value; break;
812	case UNW_ARM_R9: _msContext.R9 = value; break;
813	case UNW_ARM_R10: _msContext.R10 = value; break;
814	case UNW_ARM_R11: _msContext.R11 = value; break;
815	case UNW_ARM_R12: _msContext.R12 = value; break;
816	case UNW_REG_SP:
817	case UNW_ARM_SP: _msContext.Sp = value; break;
818	case UNW_ARM_LR: _msContext.Lr = value; break;
819	case UNW_REG_IP:
820	case UNW_ARM_IP: _msContext.Pc = value; break;
821	#elif defined(_LIBUNWIND_TARGET_AARCH64)
822	case UNW_REG_SP: _msContext.Sp = value; break;
823	case UNW_REG_IP: _msContext.Pc = value; break;
824	case UNW_AARCH64_X0:
825	case UNW_AARCH64_X1:
826	case UNW_AARCH64_X2:
827	case UNW_AARCH64_X3:
828	case UNW_AARCH64_X4:
829	case UNW_AARCH64_X5:
830	case UNW_AARCH64_X6:
831	case UNW_AARCH64_X7:
832	case UNW_AARCH64_X8:
833	case UNW_AARCH64_X9:
834	case UNW_AARCH64_X10:
835	case UNW_AARCH64_X11:
836	case UNW_AARCH64_X12:
837	case UNW_AARCH64_X13:
838	case UNW_AARCH64_X14:
839	case UNW_AARCH64_X15:
840	case UNW_AARCH64_X16:
841	case UNW_AARCH64_X17:
842	case UNW_AARCH64_X18:
843	case UNW_AARCH64_X19:
844	case UNW_AARCH64_X20:
845	case UNW_AARCH64_X21:
846	case UNW_AARCH64_X22:
847	case UNW_AARCH64_X23:
848	case UNW_AARCH64_X24:
849	case UNW_AARCH64_X25:
850	case UNW_AARCH64_X26:
851	case UNW_AARCH64_X27:
852	case UNW_AARCH64_X28:
853	case UNW_AARCH64_FP:
854	case UNW_AARCH64_LR: _msContext.X[regNum - UNW_ARM64_X0] = value; break;
855	#endif
856	default:
857	_LIBUNWIND_ABORT("unsupported register");
858	}
859	}
860
861	template <typename A, typename R>
862	bool UnwindCursor<A, R>::validFloatReg(int regNum) {
863	#if defined(_LIBUNWIND_TARGET_ARM)
864	if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) return true;
865	if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) return true;
866	#elif defined(_LIBUNWIND_TARGET_AARCH64)
867	if (regNum >= UNW_AARCH64_V0 && regNum <= UNW_ARM64_D31) return true;
868	#else
869	(void)regNum;
870	#endif
871	return false;
872	}
873
874	template <typename A, typename R>
875	unw_fpreg_t UnwindCursor<A, R>::getFloatReg(int regNum) {
876	#if defined(_LIBUNWIND_TARGET_ARM)
877	if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) {
878	union {
879	uint32_t w;
880	float f;
881	} d;
882	d.w = _msContext.S[regNum - UNW_ARM_S0];
883	return d.f;
884	}
885	if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) {
886	union {
887	uint64_t w;
888	double d;
889	} d;
890	d.w = _msContext.D[regNum - UNW_ARM_D0];
891	return d.d;
892	}
893	_LIBUNWIND_ABORT("unsupported float register");
894	#elif defined(_LIBUNWIND_TARGET_AARCH64)
895	return _msContext.V[regNum - UNW_AARCH64_V0].D[`0`];
896	#else
897	(void)regNum;
898	_LIBUNWIND_ABORT("float registers unimplemented");
899	#endif
900	}
901
902	template <typename A, typename R>
903	void UnwindCursor<A, R>::setFloatReg(int regNum, unw_fpreg_t value) {
904	#if defined(_LIBUNWIND_TARGET_ARM)
905	if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) {
906	union {
907	uint32_t w;
908	float f;
909	} d;
910	d.f = (float)value;
911	_msContext.S[regNum - UNW_ARM_S0] = d.w;
912	}
913	if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) {
914	union {
915	uint64_t w;
916	double d;
917	} d;
918	d.d = value;
919	_msContext.D[regNum - UNW_ARM_D0] = d.w;
920	}
921	_LIBUNWIND_ABORT("unsupported float register");
922	#elif defined(_LIBUNWIND_TARGET_AARCH64)
923	_msContext.V[regNum - UNW_AARCH64_V0].D[`0`] = value;
924	#else
925	(void)regNum;
926	(void)value;
927	_LIBUNWIND_ABORT("float registers unimplemented");
928	#endif
929	}
930
931	template <typename A, typename R> void UnwindCursor<A, R>::jumpto() {
932	RtlRestoreContext(&_msContext, nullptr);
933	}
934
935	#ifdef __arm__
936	template <typename A, typename R> void UnwindCursor<A, R>::saveVFPAsX() {}
937	#endif
938
939	template <typename A, typename R>
940	const char UnwindCursor<A, R>::getRegisterName(int* regNum) {
941	return R::getRegisterName(regNum);
942	}
943
944	template <typename A, typename R> bool UnwindCursor<A, R>::isSignalFrame() {
945	return false;
946	}
947
948	#else // !defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) \|\| !defined(_WIN32)
949
950	/// UnwindCursor contains all state (including all register values) during
951	/// an unwind. This is normally stack allocated inside a unw_cursor_t.
952	template <typename A, typename R>
953	class UnwindCursor : public AbstractUnwindCursor{
954	typedef typename A::pint_t pint_t;
955	public:
956	UnwindCursor(unw_context_t *context, A &as);
957	UnwindCursor(A &as, void *threadArg);
958	virtual ~UnwindCursor() {}
959	virtual bool validReg(int);
960	virtual unw_word_t getReg(int);
961	virtual void setReg(int, unw_word_t);
962	virtual bool validFloatReg(int);
963	virtual unw_fpreg_t getFloatReg(int);
964	virtual void setFloatReg(int, unw_fpreg_t);
965	virtual int step(bool stage2 = false);
966	virtual void getInfo(unw_proc_info_t *);
967	virtual void jumpto();
968	virtual bool isSignalFrame();
969	virtual bool getFunctionName(char buf, size_t len, unw_word_t off);
970	virtual void setInfoBasedOnIPRegister(bool isReturnAddress = false);
971	virtual const char getRegisterName(int* num);
972	#ifdef __arm__
973	virtual void saveVFPAsX();
974	#endif
975
976	#ifdef _AIX
977	virtual uintptr_t getDataRelBase();
978	#endif
979
980	#if defined(_LIBUNWIND_USE_CET) \|\| defined(_LIBUNWIND_USE_GCS)
981	virtual void get_registers() { return* &_registers; }
982	#endif
983
984	// libunwind does not and should not depend on C++ library which means that we
985	// need our own definition of inline placement new.
986	static void *operator new(size_t, UnwindCursor<A, R> p) { return* p; }
987
988	private:
989
990	#if defined(_LIBUNWIND_ARM_EHABI)
991	bool getInfoFromEHABISection(pint_t pc, const UnwindInfoSections &sects);
992
993	int stepWithEHABI() {
994	size_t len = `0`;
995	size_t off = `0`;
996	// FIXME: Calling decode_eht_entry() here is violating the libunwind
997	// abstraction layer.
998	const uint32_t *ehtp =
999	decode_eht_entry(reinterpret_cast<const uint32_t *>(_info.unwind_info),
1000	&off, &len);
1001	if (_Unwind_VRS_Interpret((_Unwind_Context )this*, ehtp, off, len) !=
1002	_URC_CONTINUE_UNWIND)
1003	return UNW_STEP_END;
1004	return UNW_STEP_SUCCESS;
1005	}
1006	#endif
1007
1008	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN)
1009	bool setInfoForSigReturn() {
1010	R dummy;
1011	return setInfoForSigReturn(dummy);
1012	}
1013	int stepThroughSigReturn() {
1014	R dummy;
1015	return stepThroughSigReturn(dummy);
1016	}
1017	bool isReadableAddr(const pint_t addr) const;
1018	#if defined(_LIBUNWIND_TARGET_AARCH64)
1019	bool setInfoForSigReturn(Registers_arm64 &);
1020	int stepThroughSigReturn(Registers_arm64 &);
1021	#endif
1022	#if defined(_LIBUNWIND_TARGET_LOONGARCH)
1023	bool setInfoForSigReturn(Registers_loongarch &);
1024	int stepThroughSigReturn(Registers_loongarch &);
1025	#endif
1026	#if defined(_LIBUNWIND_TARGET_RISCV)
1027	bool setInfoForSigReturn(Registers_riscv &);
1028	int stepThroughSigReturn(Registers_riscv &);
1029	#endif
1030	#if defined(_LIBUNWIND_TARGET_S390X)
1031	bool setInfoForSigReturn(Registers_s390x &);
1032	int stepThroughSigReturn(Registers_s390x &);
1033	#endif
1034	template <typename Registers> bool setInfoForSigReturn(Registers &) {
1035	return false;
1036	}
1037	template <typename Registers> int stepThroughSigReturn(Registers &) {
1038	return UNW_STEP_END;
1039	}
1040	#elif defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
1041	bool setInfoForSigReturn();
1042	int stepThroughSigReturn();
1043	#endif
1044
1045	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1046	bool getInfoFromFdeCie(const typename CFI_Parser<A>::FDE_Info &fdeInfo,
1047	const typename CFI_Parser<A>::CIE_Info &cieInfo,
1048	pint_t pc, uintptr_t dso_base);
1049	bool getInfoFromDwarfSection(pint_t pc, const UnwindInfoSections &sects,
1050	uint32_t fdeSectionOffsetHint=`0`);
1051	int stepWithDwarfFDE(bool stage2) {
1052	return DwarfInstructions<A, R>::stepWithDwarf(
1053	_addressSpace, (pint_t)this->getReg(UNW_REG_IP),
1054	(pint_t)_info.unwind_info, _registers, _isSignalFrame, stage2);
1055	}
1056	#endif
1057
1058	#if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1059	bool getInfoFromCompactEncodingSection(pint_t pc,
1060	const UnwindInfoSections &sects);
1061	int stepWithCompactEncoding(bool stage2 = false) {
1062	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1063	if ( compactSaysUseDwarf() )
1064	return stepWithDwarfFDE(stage2);
1065	#endif
1066	R dummy;
1067	return stepWithCompactEncoding(dummy);
1068	}
1069
1070	#if defined(_LIBUNWIND_TARGET_X86_64)
1071	int stepWithCompactEncoding(Registers_x86_64 &) {
1072	return CompactUnwinder_x86_64<A>::stepWithCompactEncoding(
1073	_info.format, _info.start_ip, _addressSpace, _registers);
1074	}
1075	#endif
1076
1077	#if defined(_LIBUNWIND_TARGET_I386)
1078	int stepWithCompactEncoding(Registers_x86 &) {
1079	return CompactUnwinder_x86<A>::stepWithCompactEncoding(
1080	_info.format, (uint32_t)_info.start_ip, _addressSpace, _registers);
1081	}
1082	#endif
1083
1084	#if defined(_LIBUNWIND_TARGET_PPC)
1085	int stepWithCompactEncoding(Registers_ppc &) {
1086	return UNW_EINVAL;
1087	}
1088	#endif
1089
1090	#if defined(_LIBUNWIND_TARGET_PPC64)
1091	int stepWithCompactEncoding(Registers_ppc64 &) {
1092	return UNW_EINVAL;
1093	}
1094	#endif
1095
1096
1097	#if defined(_LIBUNWIND_TARGET_AARCH64)
1098	int stepWithCompactEncoding(Registers_arm64 &) {
1099	return CompactUnwinder_arm64<A>::stepWithCompactEncoding(
1100	_info.format, _info.start_ip, _addressSpace, _registers);
1101	}
1102	#endif
1103
1104	#if defined(_LIBUNWIND_TARGET_MIPS_O32)
1105	int stepWithCompactEncoding(Registers_mips_o32 &) {
1106	return UNW_EINVAL;
1107	}
1108	#endif
1109
1110	#if defined(_LIBUNWIND_TARGET_MIPS_NEWABI)
1111	int stepWithCompactEncoding(Registers_mips_newabi &) {
1112	return UNW_EINVAL;
1113	}
1114	#endif
1115
1116	#if defined(_LIBUNWIND_TARGET_LOONGARCH)
1117	int stepWithCompactEncoding(Registers_loongarch &) { return UNW_EINVAL; }
1118	#endif
1119
1120	#if defined(_LIBUNWIND_TARGET_SPARC)
1121	int stepWithCompactEncoding(Registers_sparc &) { return UNW_EINVAL; }
1122	#endif
1123
1124	#if defined(_LIBUNWIND_TARGET_SPARC64)
1125	int stepWithCompactEncoding(Registers_sparc64 &) { return UNW_EINVAL; }
1126	#endif
1127
1128	#if defined (_LIBUNWIND_TARGET_RISCV)
1129	int stepWithCompactEncoding(Registers_riscv &) {
1130	return UNW_EINVAL;
1131	}
1132	#endif
1133
1134	bool compactSaysUseDwarf(uint32_t offset=NULL) const* {
1135	R dummy;
1136	return compactSaysUseDwarf(dummy, offset);
1137	}
1138
1139	#if defined(_LIBUNWIND_TARGET_X86_64)
1140	bool compactSaysUseDwarf(Registers_x86_64 &, uint32_t offset) const* {
1141	if ((_info.format & UNWIND_X86_64_MODE_MASK) == UNWIND_X86_64_MODE_DWARF) {
1142	if (offset)
1143	*offset = (_info.format & UNWIND_X86_64_DWARF_SECTION_OFFSET);
1144	return true;
1145	}
1146	return false;
1147	}
1148	#endif
1149
1150	#if defined(_LIBUNWIND_TARGET_I386)
1151	bool compactSaysUseDwarf(Registers_x86 &, uint32_t offset) const* {
1152	if ((_info.format & UNWIND_X86_MODE_MASK) == UNWIND_X86_MODE_DWARF) {
1153	if (offset)
1154	*offset = (_info.format & UNWIND_X86_DWARF_SECTION_OFFSET);
1155	return true;
1156	}
1157	return false;
1158	}
1159	#endif
1160
1161	#if defined(_LIBUNWIND_TARGET_PPC)
1162	bool compactSaysUseDwarf(Registers_ppc &, uint32_t ) const* {
1163	return true;
1164	}
1165	#endif
1166
1167	#if defined(_LIBUNWIND_TARGET_PPC64)
1168	bool compactSaysUseDwarf(Registers_ppc64 &, uint32_t ) const* {
1169	return true;
1170	}
1171	#endif
1172
1173	#if defined(_LIBUNWIND_TARGET_AARCH64)
1174	bool compactSaysUseDwarf(Registers_arm64 &, uint32_t offset) const* {
1175	if ((_info.format & UNWIND_ARM64_MODE_MASK) == UNWIND_ARM64_MODE_DWARF) {
1176	if (offset)
1177	*offset = (_info.format & UNWIND_ARM64_DWARF_SECTION_OFFSET);
1178	return true;
1179	}
1180	return false;
1181	}
1182	#endif
1183
1184	#if defined(_LIBUNWIND_TARGET_MIPS_O32)
1185	bool compactSaysUseDwarf(Registers_mips_o32 &, uint32_t ) const* {
1186	return true;
1187	}
1188	#endif
1189
1190	#if defined(_LIBUNWIND_TARGET_MIPS_NEWABI)
1191	bool compactSaysUseDwarf(Registers_mips_newabi &, uint32_t ) const* {
1192	return true;
1193	}
1194	#endif
1195
1196	#if defined(_LIBUNWIND_TARGET_LOONGARCH)
1197	bool compactSaysUseDwarf(Registers_loongarch &, uint32_t ) const* {
1198	return true;
1199	}
1200	#endif
1201
1202	#if defined(_LIBUNWIND_TARGET_SPARC)
1203	bool compactSaysUseDwarf(Registers_sparc &, uint32_t ) const* { return true; }
1204	#endif
1205
1206	#if defined(_LIBUNWIND_TARGET_SPARC64)
1207	bool compactSaysUseDwarf(Registers_sparc64 &, uint32_t ) const* {
1208	return true;
1209	}
1210	#endif
1211
1212	#if defined (_LIBUNWIND_TARGET_RISCV)
1213	bool compactSaysUseDwarf(Registers_riscv &, uint32_t ) const* {
1214	return true;
1215	}
1216	#endif
1217
1218	#endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1219
1220	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1221	compact_unwind_encoding_t dwarfEncoding() const {
1222	R dummy;
1223	return dwarfEncoding(dummy);
1224	}
1225
1226	#if defined(_LIBUNWIND_TARGET_X86_64)
1227	compact_unwind_encoding_t dwarfEncoding(Registers_x86_64 &) const {
1228	return UNWIND_X86_64_MODE_DWARF;
1229	}
1230	#endif
1231
1232	#if defined(_LIBUNWIND_TARGET_I386)
1233	compact_unwind_encoding_t dwarfEncoding(Registers_x86 &) const {
1234	return UNWIND_X86_MODE_DWARF;
1235	}
1236	#endif
1237
1238	#if defined(_LIBUNWIND_TARGET_PPC)
1239	compact_unwind_encoding_t dwarfEncoding(Registers_ppc &) const {
1240	return `0`;
1241	}
1242	#endif
1243
1244	#if defined(_LIBUNWIND_TARGET_PPC64)
1245	compact_unwind_encoding_t dwarfEncoding(Registers_ppc64 &) const {
1246	return `0`;
1247	}
1248	#endif
1249
1250	#if defined(_LIBUNWIND_TARGET_AARCH64)
1251	compact_unwind_encoding_t dwarfEncoding(Registers_arm64 &) const {
1252	return UNWIND_ARM64_MODE_DWARF;
1253	}
1254	#endif
1255
1256	#if defined(_LIBUNWIND_TARGET_ARM)
1257	compact_unwind_encoding_t dwarfEncoding(Registers_arm &) const {
1258	return `0`;
1259	}
1260	#endif
1261
1262	#if defined (_LIBUNWIND_TARGET_OR1K)
1263	compact_unwind_encoding_t dwarfEncoding(Registers_or1k &) const {
1264	return `0`;
1265	}
1266	#endif
1267
1268	#if defined (_LIBUNWIND_TARGET_HEXAGON)
1269	compact_unwind_encoding_t dwarfEncoding(Registers_hexagon &) const {
1270	return `0`;
1271	}
1272	#endif
1273
1274	#if defined (_LIBUNWIND_TARGET_MIPS_O32)
1275	compact_unwind_encoding_t dwarfEncoding(Registers_mips_o32 &) const {
1276	return `0`;
1277	}
1278	#endif
1279
1280	#if defined (_LIBUNWIND_TARGET_MIPS_NEWABI)
1281	compact_unwind_encoding_t dwarfEncoding(Registers_mips_newabi &) const {
1282	return `0`;
1283	}
1284	#endif
1285
1286	#if defined(_LIBUNWIND_TARGET_LOONGARCH)
1287	compact_unwind_encoding_t dwarfEncoding(Registers_loongarch &) const {
1288	return `0`;
1289	}
1290	#endif
1291
1292	#if defined(_LIBUNWIND_TARGET_SPARC)
1293	compact_unwind_encoding_t dwarfEncoding(Registers_sparc &) const { return `0`; }
1294	#endif
1295
1296	#if defined(_LIBUNWIND_TARGET_SPARC64)
1297	compact_unwind_encoding_t dwarfEncoding(Registers_sparc64 &) const {
1298	return `0`;
1299	}
1300	#endif
1301
1302	#if defined (_LIBUNWIND_TARGET_RISCV)
1303	compact_unwind_encoding_t dwarfEncoding(Registers_riscv &) const {
1304	return `0`;
1305	}
1306	#endif
1307
1308	#if defined (_LIBUNWIND_TARGET_S390X)
1309	compact_unwind_encoding_t dwarfEncoding(Registers_s390x &) const {
1310	return `0`;
1311	}
1312	#endif
1313
1314	#endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1315
1316	#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1317	// For runtime environments using SEH unwind data without Windows runtime
1318	// support.
1319	pint_t getLastPC() const { / FIXME: Implement / return `0`; }
1320	void setLastPC(pint_t pc) { / FIXME: Implement / }
1321	RUNTIME_FUNCTION lookUpSEHUnwindInfo(pint_t pc, pint_t base) {
1322	/ FIXME: Implement /
1323	*base = `0`;
1324	return nullptr;
1325	}
1326	bool getInfoFromSEH(pint_t pc);
1327	int stepWithSEHData() { / FIXME: Implement / return `0`; }
1328	#endif // defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1329
1330	#if defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
1331	bool getInfoFromTBTable(pint_t pc, R &registers);
1332	int stepWithTBTable(pint_t pc, tbtable *TBTable, R &registers,
1333	bool &isSignalFrame);
1334	int stepWithTBTableData() {
1335	return stepWithTBTable(reinterpret_cast<pint_t>(this->getReg(UNW_REG_IP)),
1336	reinterpret_cast<tbtable *>(_info.unwind_info),
1337	_registers, _isSignalFrame);
1338	}
1339	#endif // defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
1340
1341	A &_addressSpace;
1342	R _registers;
1343	unw_proc_info_t _info;
1344	bool _unwindInfoMissing;
1345	bool _isSignalFrame;
1346	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) \|\| \
1347	defined(_LIBUNWIND_TARGET_HAIKU)
1348	bool _isSigReturn = false;
1349	#endif
1350	};
1351
1352
1353	template <typename A, typename R>
1354	UnwindCursor<A, R>::UnwindCursor(unw_context_t *context, A &as)
1355	: _addressSpace(as), _registers(context), _unwindInfoMissing(false),
1356	_isSignalFrame(false) {
1357	static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
1358	"UnwindCursor<> does not fit in unw_cursor_t");
1359	static_assert((alignof(UnwindCursor<A, R>) <= alignof(unw_cursor_t)),
1360	"UnwindCursor<> requires more alignment than unw_cursor_t");
1361	memset(s: &_info, c: `0`, n: sizeof(_info));
1362	}
1363
1364	template <typename A, typename R>
1365	UnwindCursor<A, R>::UnwindCursor(A &as, void *)
1366	: _addressSpace(as), _unwindInfoMissing(false), _isSignalFrame(false) {
1367	memset(s: &_info, c: `0`, n: sizeof(_info));
1368	// FIXME
1369	// fill in _registers from thread arg
1370	}
1371
1372
1373	template <typename A, typename R>
1374	bool UnwindCursor<A, R>::validReg(int regNum) {
1375	return _registers.validRegister(regNum);
1376	}
1377
1378	template <typename A, typename R>
1379	unw_word_t UnwindCursor<A, R>::getReg(int regNum) {
1380	return _registers.getRegister(regNum);
1381	}
1382
1383	template <typename A, typename R>
1384	void UnwindCursor<A, R>::setReg(int regNum, unw_word_t value) {
1385	_registers.setRegister(regNum, (typename A::pint_t)value);
1386	}
1387
1388	template <typename A, typename R>
1389	bool UnwindCursor<A, R>::validFloatReg(int regNum) {
1390	return _registers.validFloatRegister(regNum);
1391	}
1392
1393	template <typename A, typename R>
1394	unw_fpreg_t UnwindCursor<A, R>::getFloatReg(int regNum) {
1395	return _registers.getFloatRegister(regNum);
1396	}
1397
1398	template <typename A, typename R>
1399	void UnwindCursor<A, R>::setFloatReg(int regNum, unw_fpreg_t value) {
1400	_registers.setFloatRegister(regNum, value);
1401	}
1402
1403	template <typename A, typename R> void UnwindCursor<A, R>::jumpto() {
1404	_registers.jumpto();
1405	}
1406
1407	#ifdef __arm__
1408	template <typename A, typename R> void UnwindCursor<A, R>::saveVFPAsX() {
1409	_registers.saveVFPAsX();
1410	}
1411	#endif
1412
1413	#ifdef _AIX
1414	template <typename A, typename R>
1415	uintptr_t UnwindCursor<A, R>::getDataRelBase() {
1416	return reinterpret_cast<uintptr_t>(_info.extra);
1417	}
1418	#endif
1419
1420	template <typename A, typename R>
1421	const char UnwindCursor<A, R>::getRegisterName(int* regNum) {
1422	return _registers.getRegisterName(regNum);
1423	}
1424
1425	template <typename A, typename R> bool UnwindCursor<A, R>::isSignalFrame() {
1426	return _isSignalFrame;
1427	}
1428
1429	#endif // defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1430
1431	#if defined(_LIBUNWIND_ARM_EHABI)
1432	template<typename A>
1433	struct EHABISectionIterator {
1434	typedef EHABISectionIterator _Self;
1435
1436	typedef typename A::pint_t value_type;
1437	typedef typename A::pint_t* pointer;
1438	typedef typename A::pint_t& reference;
1439	typedef size_t size_type;
1440	typedef size_t difference_type;
1441
1442	static _Self begin(A& addressSpace, const UnwindInfoSections& sects) {
1443	return _Self(addressSpace, sects, `0`);
1444	}
1445	static _Self end(A& addressSpace, const UnwindInfoSections& sects) {
1446	return _Self(addressSpace, sects,
1447	sects.arm_section_length / sizeof(EHABIIndexEntry));
1448	}
1449
1450	EHABISectionIterator(A& addressSpace, const UnwindInfoSections& sects, size_t i)
1451	: _i(i), _addressSpace(&addressSpace), _sects(&sects) {}
1452
1453	_Self& operator++() { ++_i; return *this; }
1454	_Self& operator+=(size_t a) { _i += a; return *this; }
1455	_Self& operator--() { assert(_i > `0`); --_i; return *this; }
1456	_Self& operator-=(size_t a) { assert(_i >= a); _i -= a; return *this; }
1457
1458	_Self operator+(size_t a) { _Self out = *this; out._i += a; return out; }
1459	_Self operator-(size_t a) { assert(_i >= a); _Self out = *this; out._i -= a; return out; }
1460
1461	size_t operator-(const _Self& other) const { return _i - other._i; }
1462
1463	bool operator==(const _Self& other) const {
1464	assert(_addressSpace == other._addressSpace);
1465	assert(_sects == other._sects);
1466	return _i == other._i;
1467	}
1468
1469	bool operator!=(const _Self& other) const {
1470	assert(_addressSpace == other._addressSpace);
1471	assert(_sects == other._sects);
1472	return _i != other._i;
1473	}
1474
1475	typename A::pint_t operator() const* { return functionAddress(); }
1476
1477	typename A::pint_t functionAddress() const {
1478	typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
1479	EHABIIndexEntry, _i, functionOffset);
1480	return indexAddr + signExtendPrel31(_addressSpace->get32(indexAddr));
1481	}
1482
1483	typename A::pint_t dataAddress() {
1484	typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
1485	EHABIIndexEntry, _i, data);
1486	return indexAddr;
1487	}
1488
1489	private:
1490	size_t _i;
1491	A* _addressSpace;
1492	const UnwindInfoSections* _sects;
1493	};
1494
1495	namespace {
1496
1497	template <typename A>
1498	EHABISectionIterator<A> EHABISectionUpperBound(
1499	EHABISectionIterator<A> first,
1500	EHABISectionIterator<A> last,
1501	typename A::pint_t value) {
1502	size_t len = last - first;
1503	while (len > `0`) {
1504	size_t l2 = len / `2`;
1505	EHABISectionIterator<A> m = first + l2;
1506	if (value < *m) {
1507	len = l2;
1508	} else {
1509	first = ++m;
1510	len -= l2 + `1`;
1511	}
1512	}
1513	return first;
1514	}
1515
1516	}
1517
1518	template <typename A, typename R>
1519	bool UnwindCursor<A, R>::getInfoFromEHABISection(
1520	pint_t pc,
1521	const UnwindInfoSections &sects) {
1522	EHABISectionIterator<A> begin =
1523	EHABISectionIterator<A>::begin(_addressSpace, sects);
1524	EHABISectionIterator<A> end =
1525	EHABISectionIterator<A>::end(_addressSpace, sects);
1526	if (begin == end)
1527	return false;
1528
1529	EHABISectionIterator<A> itNextPC = EHABISectionUpperBound(begin, end, pc);
1530	if (itNextPC == begin)
1531	return false;
1532	EHABISectionIterator<A> itThisPC = itNextPC - `1`;
1533
1534	pint_t thisPC = itThisPC.functionAddress();
1535	// If an exception is thrown from a function, corresponding to the last entry
1536	// in the table, we don't really know the function extent and have to choose a
1537	// value for nextPC. Choosing max() will allow the range check during trace to
1538	// succeed.
1539	pint_t nextPC = (itNextPC == end) ? UINTPTR_MAX : itNextPC.functionAddress();
1540	pint_t indexDataAddr = itThisPC.dataAddress();
1541
1542	if (indexDataAddr == `0`)
1543	return false;
1544
1545	uint32_t indexData = _addressSpace.get32(indexDataAddr);
1546	if (indexData == UNW_EXIDX_CANTUNWIND)
1547	return false;
1548
1549	// If the high bit is set, the exception handling table entry is inline inside
1550	// the index table entry on the second word (aka \|indexDataAddr\|). Otherwise,
1551	// the table points at an offset in the exception handling table (section 5
1552	// EHABI).
1553	pint_t exceptionTableAddr;
1554	uint32_t exceptionTableData;
1555	bool isSingleWordEHT;
1556	if (indexData & `0x80000000`) {
1557	exceptionTableAddr = indexDataAddr;
1558	// TODO(ajwong): Should this data be 0?
1559	exceptionTableData = indexData;
1560	isSingleWordEHT = true;
1561	} else {
1562	exceptionTableAddr = indexDataAddr + signExtendPrel31(indexData);
1563	exceptionTableData = _addressSpace.get32(exceptionTableAddr);
1564	isSingleWordEHT = false;
1565	}
1566
1567	// Now we know the 3 things:
1568	// exceptionTableAddr -- exception handler table entry.
1569	// exceptionTableData -- the data inside the first word of the eht entry.
1570	// isSingleWordEHT -- whether the entry is in the index.
1571	unw_word_t personalityRoutine = `0xbadf00d`;
1572	bool scope32 = false;
1573	uintptr_t lsda;
1574
1575	// If the high bit in the exception handling table entry is set, the entry is
1576	// in compact form (section 6.3 EHABI).
1577	if (exceptionTableData & `0x80000000`) {
1578	// Grab the index of the personality routine from the compact form.
1579	uint32_t choice = (exceptionTableData & `0x0f000000`) >> `24`;
1580	uint32_t extraWords = `0`;
1581	switch (choice) {
1582	case `0`:
1583	personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr0;
1584	extraWords = `0`;
1585	scope32 = false;
1586	lsda = isSingleWordEHT ? `0` : (exceptionTableAddr + `4`);
1587	break;
1588	case `1`:
1589	personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr1;
1590	extraWords = (exceptionTableData & `0x00ff0000`) >> `16`;
1591	scope32 = false;
1592	lsda = exceptionTableAddr + (extraWords + `1`) * `4`;
1593	break;
1594	case `2`:
1595	personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr2;
1596	extraWords = (exceptionTableData & `0x00ff0000`) >> `16`;
1597	scope32 = true;
1598	lsda = exceptionTableAddr + (extraWords + `1`) * `4`;
1599	break;
1600	default:
1601	_LIBUNWIND_ABORT("unknown personality routine");
1602	return false;
1603	}
1604
1605	if (isSingleWordEHT) {
1606	if (extraWords != `0`) {
1607	_LIBUNWIND_ABORT("index inlined table detected but pr function "
1608	"requires extra words");
1609	return false;
1610	}
1611	}
1612	} else {
1613	pint_t personalityAddr =
1614	exceptionTableAddr + signExtendPrel31(exceptionTableData);
1615	personalityRoutine = personalityAddr;
1616
1617	// ARM EHABI # 6.2, # 9.2
1618	//
1619	// +---- ehtp
1620	// v
1621	// +--------------------------------------+
1622	// \| +--------+--------+--------+-------+ \|
1623	// \| \|0\| prel31 to personalityRoutine \| \|
1624	// \| +--------+--------+--------+-------+ \|
1625	// \| \| N \| unwind opcodes \| \| <-- UnwindData
1626	// \| +--------+--------+--------+-------+ \|
1627	// \| \| Word 2 unwind opcodes \| \|
1628	// \| +--------+--------+--------+-------+ \|
1629	// \| ... \|
1630	// \| +--------+--------+--------+-------+ \|
1631	// \| \| Word N unwind opcodes \| \|
1632	// \| +--------+--------+--------+-------+ \|
1633	// \| \| LSDA \| \| <-- lsda
1634	// \| \| ... \| \|
1635	// \| +--------+--------+--------+-------+ \|
1636	// +--------------------------------------+
1637
1638	uint32_t UnwindData = reinterpret_cast<uint32_t>(exceptionTableAddr) + `1`;
1639	uint32_t FirstDataWord = *UnwindData;
1640	size_t N = ((FirstDataWord >> `24`) & `0xff`);
1641	size_t NDataWords = N + `1`;
1642	lsda = reinterpret_cast<uintptr_t>(UnwindData + NDataWords);
1643	}
1644
1645	_info.start_ip = thisPC;
1646	_info.end_ip = nextPC;
1647	_info.handler = personalityRoutine;
1648	_info.unwind_info = exceptionTableAddr;
1649	_info.lsda = lsda;
1650	// flags is pr_cache.additional. See EHABI #7.2 for definition of bit 0.
1651	_info.flags = (isSingleWordEHT ? `1` : `0`) \| (scope32 ? `0x2` : `0`); // Use enum?
1652
1653	return true;
1654	}
1655	#endif
1656
1657	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1658	template <typename A, typename R>
1659	bool UnwindCursor<A, R>::getInfoFromFdeCie(
1660	const typename CFI_Parser<A>::FDE_Info &fdeInfo,
1661	const typename CFI_Parser<A>::CIE_Info &cieInfo, pint_t pc,
1662	uintptr_t dso_base) {
1663	typename CFI_Parser<A>::PrologInfo prolog;
1664	if (CFI_Parser<A>::parseFDEInstructions(_addressSpace, fdeInfo, cieInfo, pc,
1665	R::getArch(), &prolog)) {
1666	// Save off parsed FDE info
1667	_info.start_ip = fdeInfo.pcStart;
1668	_info.end_ip = fdeInfo.pcEnd;
1669	_info.lsda = fdeInfo.lsda;
1670	_info.handler = cieInfo.personality;
1671	// Some frameless functions need SP altered when resuming in function, so
1672	// propagate spExtraArgSize.
1673	_info.gp = prolog.spExtraArgSize;
1674	_info.flags = `0`;
1675	_info.format = dwarfEncoding();
1676	_info.unwind_info = fdeInfo.fdeStart;
1677	_info.unwind_info_size = static_cast<uint32_t>(fdeInfo.fdeLength);
1678	_info.extra = static_cast<unw_word_t>(dso_base);
1679	return true;
1680	}
1681	return false;
1682	}
1683
1684	template <typename A, typename R>
1685	bool UnwindCursor<A, R>::getInfoFromDwarfSection(pint_t pc,
1686	const UnwindInfoSections &sects,
1687	uint32_t fdeSectionOffsetHint) {
1688	typename CFI_Parser<A>::FDE_Info fdeInfo;
1689	typename CFI_Parser<A>::CIE_Info cieInfo;
1690	bool foundFDE = false;
1691	bool foundInCache = false;
1692	// If compact encoding table gave offset into dwarf section, go directly there
1693	if (fdeSectionOffsetHint != `0`) {
1694	foundFDE = CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
1695	sects.dwarf_section_length,
1696	sects.dwarf_section + fdeSectionOffsetHint,
1697	&fdeInfo, &cieInfo);
1698	}
1699	#if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
1700	if (!foundFDE && (sects.dwarf_index_section != `0`)) {
1701	foundFDE = EHHeaderParser<A>::findFDE(
1702	_addressSpace, pc, sects.dwarf_index_section,
1703	(uint32_t)sects.dwarf_index_section_length, &fdeInfo, &cieInfo);
1704	}
1705	#endif
1706	if (!foundFDE) {
1707	// otherwise, search cache of previously found FDEs.
1708	pint_t cachedFDE = DwarfFDECache<A>::findFDE(sects.dso_base, pc);
1709	if (cachedFDE != `0`) {
1710	foundFDE =
1711	CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
1712	sects.dwarf_section_length,
1713	cachedFDE, &fdeInfo, &cieInfo);
1714	foundInCache = foundFDE;
1715	}
1716	}
1717	if (!foundFDE) {
1718	// Still not found, do full scan of __eh_frame section.
1719	foundFDE = CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
1720	sects.dwarf_section_length, `0`,
1721	&fdeInfo, &cieInfo);
1722	}
1723	if (foundFDE) {
1724	if (getInfoFromFdeCie(fdeInfo, cieInfo, pc, dso_base: sects.dso_base)) {
1725	// Add to cache (to make next lookup faster) if we had no hint
1726	// and there was no index.
1727	if (!foundInCache && (fdeSectionOffsetHint == `0`)) {
1728	#if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
1729	if (sects.dwarf_index_section == `0`)
1730	#endif
1731	DwarfFDECache<A>::add(sects.dso_base, fdeInfo.pcStart, fdeInfo.pcEnd,
1732	fdeInfo.fdeStart);
1733	}
1734	return true;
1735	}
1736	}
1737	//_LIBUNWIND_DEBUG_LOG("can't find/use FDE for pc=0x%llX", (uint64_t)pc);
1738	return false;
1739	}
1740	#endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1741
1742
1743	#if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1744	template <typename A, typename R>
1745	bool UnwindCursor<A, R>::getInfoFromCompactEncodingSection(pint_t pc,
1746	const UnwindInfoSections &sects) {
1747	const bool log = false;
1748	if (log)
1749	fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX, mh=0x%llX)\n",
1750	(uint64_t)pc, (uint64_t)sects.dso_base);
1751
1752	const UnwindSectionHeader<A> sectionHeader(_addressSpace,
1753	sects.compact_unwind_section);
1754	if (sectionHeader.version() != UNWIND_SECTION_VERSION)
1755	return false;
1756
1757	// do a binary search of top level index to find page with unwind info
1758	pint_t targetFunctionOffset = pc - sects.dso_base;
1759	const UnwindSectionIndexArray<A> topIndex(_addressSpace,
1760	sects.compact_unwind_section
1761	+ sectionHeader.indexSectionOffset());
1762	uint32_t low = `0`;
1763	uint32_t high = sectionHeader.indexCount();
1764	uint32_t last = high - `1`;
1765	while (low < high) {
1766	uint32_t mid = (low + high) / `2`;
1767	//if ( log ) fprintf(stderr, "\tmid=%d, low=%d, high=%d, mid=0x%08X\n",*
1768	//mid, low, high, topIndex.functionOffset(mid));
1769	if (topIndex.functionOffset(mid) <= targetFunctionOffset) {
1770	if ((mid == last) \|\|
1771	(topIndex.functionOffset(mid + `1`) > targetFunctionOffset)) {
1772	low = mid;
1773	break;
1774	} else {
1775	low = mid + `1`;
1776	}
1777	} else {
1778	high = mid;
1779	}
1780	}
1781	const uint32_t firstLevelFunctionOffset = topIndex.functionOffset(low);
1782	const uint32_t firstLevelNextPageFunctionOffset =
1783	topIndex.functionOffset(low + `1`);
1784	const pint_t secondLevelAddr =
1785	sects.compact_unwind_section + topIndex.secondLevelPagesSectionOffset(low);
1786	const pint_t lsdaArrayStartAddr =
1787	sects.compact_unwind_section + topIndex.lsdaIndexArraySectionOffset(low);
1788	const pint_t lsdaArrayEndAddr =
1789	sects.compact_unwind_section + topIndex.lsdaIndexArraySectionOffset(low+`1`);
1790	if (log)
1791	fprintf(stderr, "\tfirst level search for result index=%d "
1792	"to secondLevelAddr=0x%llX\n",
1793	low, (uint64_t) secondLevelAddr);
1794	// do a binary search of second level page index
1795	uint32_t encoding = `0`;
1796	pint_t funcStart = `0`;
1797	pint_t funcEnd = `0`;
1798	pint_t lsda = `0`;
1799	pint_t personality = `0`;
1800	uint32_t pageKind = _addressSpace.get32(secondLevelAddr);
1801	if (pageKind == UNWIND_SECOND_LEVEL_REGULAR) {
1802	// regular page
1803	UnwindSectionRegularPageHeader<A> pageHeader(_addressSpace,
1804	secondLevelAddr);
1805	UnwindSectionRegularArray<A> pageIndex(
1806	_addressSpace, secondLevelAddr + pageHeader.entryPageOffset());
1807	// binary search looks for entry with e where index[e].offset <= pc <
1808	// index[e+1].offset
1809	if (log)
1810	fprintf(stderr, "\tbinary search for targetFunctionOffset=0x%08llX in "
1811	"regular page starting at secondLevelAddr=0x%llX\n",
1812	(uint64_t) targetFunctionOffset, (uint64_t) secondLevelAddr);
1813	low = `0`;
1814	high = pageHeader.entryCount();
1815	while (low < high) {
1816	uint32_t mid = (low + high) / `2`;
1817	if (pageIndex.functionOffset(mid) <= targetFunctionOffset) {
1818	if (mid == (uint32_t)(pageHeader.entryCount() - `1`)) {
1819	// at end of table
1820	low = mid;
1821	funcEnd = firstLevelNextPageFunctionOffset + sects.dso_base;
1822	break;
1823	} else if (pageIndex.functionOffset(mid + `1`) > targetFunctionOffset) {
1824	// next is too big, so we found it
1825	low = mid;
1826	funcEnd = pageIndex.functionOffset(low + `1`) + sects.dso_base;
1827	break;
1828	} else {
1829	low = mid + `1`;
1830	}
1831	} else {
1832	high = mid;
1833	}
1834	}
1835	encoding = pageIndex.encoding(low);
1836	funcStart = pageIndex.functionOffset(low) + sects.dso_base;
1837	if (pc < funcStart) {
1838	if (log)
1839	fprintf(
1840	stderr,
1841	"\tpc not in table, pc=0x%llX, funcStart=0x%llX, funcEnd=0x%llX\n",
1842	(uint64_t) pc, (uint64_t) funcStart, (uint64_t) funcEnd);
1843	return false;
1844	}
1845	if (pc > funcEnd) {
1846	if (log)
1847	fprintf(
1848	stderr,
1849	"\tpc not in table, pc=0x%llX, funcStart=0x%llX, funcEnd=0x%llX\n",
1850	(uint64_t) pc, (uint64_t) funcStart, (uint64_t) funcEnd);
1851	return false;
1852	}
1853	} else if (pageKind == UNWIND_SECOND_LEVEL_COMPRESSED) {
1854	// compressed page
1855	UnwindSectionCompressedPageHeader<A> pageHeader(_addressSpace,
1856	secondLevelAddr);
1857	UnwindSectionCompressedArray<A> pageIndex(
1858	_addressSpace, secondLevelAddr + pageHeader.entryPageOffset());
1859	const uint32_t targetFunctionPageOffset =
1860	(uint32_t)(targetFunctionOffset - firstLevelFunctionOffset);
1861	// binary search looks for entry with e where index[e].offset <= pc <
1862	// index[e+1].offset
1863	if (log)
1864	fprintf(stderr, "\tbinary search of compressed page starting at "
1865	"secondLevelAddr=0x%llX\n",
1866	(uint64_t) secondLevelAddr);
1867	low = `0`;
1868	last = pageHeader.entryCount() - `1`;
1869	high = pageHeader.entryCount();
1870	while (low < high) {
1871	uint32_t mid = (low + high) / `2`;
1872	if (pageIndex.functionOffset(mid) <= targetFunctionPageOffset) {
1873	if ((mid == last) \|\|
1874	(pageIndex.functionOffset(mid + `1`) > targetFunctionPageOffset)) {
1875	low = mid;
1876	break;
1877	} else {
1878	low = mid + `1`;
1879	}
1880	} else {
1881	high = mid;
1882	}
1883	}
1884	funcStart = pageIndex.functionOffset(low) + firstLevelFunctionOffset
1885	+ sects.dso_base;
1886	if (low < last)
1887	funcEnd =
1888	pageIndex.functionOffset(low + `1`) + firstLevelFunctionOffset
1889	+ sects.dso_base;
1890	else
1891	funcEnd = firstLevelNextPageFunctionOffset + sects.dso_base;
1892	if (pc < funcStart) {
1893	_LIBUNWIND_DEBUG_LOG("malformed __unwind_info, pc=0x%llX "
1894	"not in second level compressed unwind table. "
1895	"funcStart=0x%llX",
1896	(uint64_t) pc, (uint64_t) funcStart);
1897	return false;
1898	}
1899	if (pc > funcEnd) {
1900	_LIBUNWIND_DEBUG_LOG("malformed __unwind_info, pc=0x%llX "
1901	"not in second level compressed unwind table. "
1902	"funcEnd=0x%llX",
1903	(uint64_t) pc, (uint64_t) funcEnd);
1904	return false;
1905	}
1906	uint16_t encodingIndex = pageIndex.encodingIndex(low);
1907	if (encodingIndex < sectionHeader.commonEncodingsArrayCount()) {
1908	// encoding is in common table in section header
1909	encoding = _addressSpace.get32(
1910	sects.compact_unwind_section +
1911	sectionHeader.commonEncodingsArraySectionOffset() +
1912	encodingIndex * sizeof(uint32_t));
1913	} else {
1914	// encoding is in page specific table
1915	uint16_t pageEncodingIndex =
1916	encodingIndex - (uint16_t)sectionHeader.commonEncodingsArrayCount();
1917	encoding = _addressSpace.get32(secondLevelAddr +
1918	pageHeader.encodingsPageOffset() +
1919	pageEncodingIndex * sizeof(uint32_t));
1920	}
1921	} else {
1922	_LIBUNWIND_DEBUG_LOG(
1923	"malformed __unwind_info at 0x%0llX bad second level page",
1924	(uint64_t)sects.compact_unwind_section);
1925	return false;
1926	}
1927
1928	// look up LSDA, if encoding says function has one
1929	if (encoding & UNWIND_HAS_LSDA) {
1930	UnwindSectionLsdaArray<A> lsdaIndex(_addressSpace, lsdaArrayStartAddr);
1931	uint32_t funcStartOffset = (uint32_t)(funcStart - sects.dso_base);
1932	low = `0`;
1933	high = (uint32_t)(lsdaArrayEndAddr - lsdaArrayStartAddr) /
1934	sizeof(unwind_info_section_header_lsda_index_entry);
1935	// binary search looks for entry with exact match for functionOffset
1936	if (log)
1937	fprintf(stderr,
1938	"\tbinary search of lsda table for targetFunctionOffset=0x%08X\n",
1939	funcStartOffset);
1940	while (low < high) {
1941	uint32_t mid = (low + high) / `2`;
1942	if (lsdaIndex.functionOffset(mid) == funcStartOffset) {
1943	lsda = lsdaIndex.lsdaOffset(mid) + sects.dso_base;
1944	break;
1945	} else if (lsdaIndex.functionOffset(mid) < funcStartOffset) {
1946	low = mid + `1`;
1947	} else {
1948	high = mid;
1949	}
1950	}
1951	if (lsda == `0`) {
1952	_LIBUNWIND_DEBUG_LOG("found encoding 0x%08X with HAS_LSDA bit set for "
1953	"pc=0x%0llX, but lsda table has no entry",
1954	encoding, (uint64_t) pc);
1955	return false;
1956	}
1957	}
1958
1959	// extract personality routine, if encoding says function has one
1960	uint32_t personalityIndex = (encoding & UNWIND_PERSONALITY_MASK) >>
1961	(__builtin_ctz(UNWIND_PERSONALITY_MASK));
1962	if (personalityIndex != `0`) {
1963	--personalityIndex; // change 1-based to zero-based index
1964	if (personalityIndex >= sectionHeader.personalityArrayCount()) {
1965	_LIBUNWIND_DEBUG_LOG("found encoding 0x%08X with personality index %d, "
1966	"but personality table has only %d entries",
1967	encoding, personalityIndex,
1968	sectionHeader.personalityArrayCount());
1969	return false;
1970	}
1971	int32_t personalityDelta = (int32_t)_addressSpace.get32(
1972	sects.compact_unwind_section +
1973	sectionHeader.personalityArraySectionOffset() +
1974	personalityIndex * sizeof(uint32_t));
1975	pint_t personalityPointer = sects.dso_base + (pint_t)personalityDelta;
1976	personality = _addressSpace.getP(personalityPointer);
1977	if (log)
1978	fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX), "
1979	"personalityDelta=0x%08X, personality=0x%08llX\n",
1980	(uint64_t) pc, personalityDelta, (uint64_t) personality);
1981	}
1982
1983	if (log)
1984	fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX), "
1985	"encoding=0x%08X, lsda=0x%08llX for funcStart=0x%llX\n",
1986	(uint64_t) pc, encoding, (uint64_t) lsda, (uint64_t) funcStart);
1987	_info.start_ip = funcStart;
1988	_info.end_ip = funcEnd;
1989	_info.lsda = lsda;
1990	_info.handler = personality;
1991	_info.gp = `0`;
1992	_info.flags = `0`;
1993	_info.format = encoding;
1994	_info.unwind_info = `0`;
1995	_info.unwind_info_size = `0`;
1996	_info.extra = sects.dso_base;
1997	return true;
1998	}
1999	#endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
2000
2001
2002	#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
2003	template <typename A, typename R>
2004	bool UnwindCursor<A, R>::getInfoFromSEH(pint_t pc) {
2005	pint_t base;
2006	RUNTIME_FUNCTION *unwindEntry = lookUpSEHUnwindInfo(pc, &base);
2007	if (!unwindEntry) {
2008	_LIBUNWIND_DEBUG_LOG("\tpc not in table, pc=0x%llX", (uint64_t) pc);
2009	return false;
2010	}
2011	_info.gp = `0`;
2012	_info.flags = `0`;
2013	_info.format = `0`;
2014	_info.unwind_info_size = sizeof(RUNTIME_FUNCTION);
2015	_info.unwind_info = reinterpret_cast<unw_word_t>(unwindEntry);
2016	_info.extra = base;
2017	_info.start_ip = base + unwindEntry->BeginAddress;
2018	#ifdef _LIBUNWIND_TARGET_X86_64
2019	_info.end_ip = base + unwindEntry->EndAddress;
2020	// Only fill in the handler and LSDA if they're stale.
2021	if (pc != getLastPC()) {
2022	UNWIND_INFO xdata = reinterpret_cast<UNWIND_INFO >(base + unwindEntry->UnwindData);
2023	if (xdata->Flags & (UNW_FLAG_EHANDLER\|UNW_FLAG_UHANDLER)) {
2024	// The personality is given in the UNWIND_INFO itself. The LSDA immediately
2025	// follows the UNWIND_INFO. (This follows how both Clang and MSVC emit
2026	// these structures.)
2027	// N.B. UNWIND_INFO structs are DWORD-aligned.
2028	uint32_t lastcode = (xdata->CountOfCodes + `1`) & ~`1`;
2029	const uint32_t handler = reinterpret_cast<uint32_t >(&xdata->UnwindCodes[lastcode]);
2030	_info.lsda = reinterpret_cast<unw_word_t>(handler+`1`);
2031	_dispContext.HandlerData = reinterpret_cast<void *>(_info.lsda);
2032	_dispContext.LanguageHandler =
2033	reinterpret_cast<EXCEPTION_ROUTINE >(base + handler);
2034	if (*handler) {
2035	_info.handler = reinterpret_cast<unw_word_t>(__libunwind_seh_personality);
2036	} else
2037	_info.handler = `0`;
2038	} else {
2039	_info.lsda = `0`;
2040	_info.handler = `0`;
2041	}
2042	}
2043	#elif defined(_LIBUNWIND_TARGET_AARCH64) \|\| defined(_LIBUNWIND_TARGET_ARM)
2044
2045	#if defined(_LIBUNWIND_TARGET_AARCH64)
2046	#define FUNC_LENGTH_UNIT 4
2047	#define XDATA_TYPE IMAGE_ARM64_RUNTIME_FUNCTION_ENTRY_XDATA
2048	#else
2049	#define FUNC_LENGTH_UNIT 2
2050	#define XDATA_TYPE UNWIND_INFO_ARM
2051	#endif
2052	if (unwindEntry->Flag != `0`) { // Packed unwind info
2053	_info.end_ip =
2054	_info.start_ip + unwindEntry->FunctionLength * FUNC_LENGTH_UNIT;
2055	// Only fill in the handler and LSDA if they're stale.
2056	if (pc != getLastPC()) {
2057	// Packed unwind info doesn't have an exception handler.
2058	_info.lsda = `0`;
2059	_info.handler = `0`;
2060	}
2061	} else {
2062	XDATA_TYPE *xdata =
2063	reinterpret_cast<XDATA_TYPE *>(base + unwindEntry->UnwindData);
2064	_info.end_ip = _info.start_ip + xdata->FunctionLength * FUNC_LENGTH_UNIT;
2065	// Only fill in the handler and LSDA if they're stale.
2066	if (pc != getLastPC()) {
2067	if (xdata->ExceptionDataPresent) {
2068	uint32_t offset = `1`; // The main xdata
2069	uint32_t codeWords = xdata->CodeWords;
2070	uint32_t epilogScopes = xdata->EpilogCount;
2071	if (xdata->EpilogCount == `0` && xdata->CodeWords == `0`) {
2072	// The extension word has got the same layout for both ARM and ARM64
2073	uint32_t extensionWord = reinterpret_cast<uint32_t *>(xdata)[`1`];
2074	codeWords = (extensionWord >> `16`) & `0xff`;
2075	epilogScopes = extensionWord & `0xffff`;
2076	offset++;
2077	}
2078	if (!xdata->EpilogInHeader)
2079	offset += epilogScopes;
2080	offset += codeWords;
2081	uint32_t *exceptionHandlerInfo =
2082	reinterpret_cast<uint32_t *>(xdata) + offset;
2083	_dispContext.HandlerData = &exceptionHandlerInfo[`1`];
2084	_dispContext.LanguageHandler = reinterpret_cast<EXCEPTION_ROUTINE *>(
2085	base + exceptionHandlerInfo[`0`]);
2086	_info.lsda = reinterpret_cast<unw_word_t>(_dispContext.HandlerData);
2087	if (exceptionHandlerInfo[`0`])
2088	_info.handler =
2089	reinterpret_cast<unw_word_t>(__libunwind_seh_personality);
2090	else
2091	_info.handler = `0`;
2092	} else {
2093	_info.lsda = `0`;
2094	_info.handler = `0`;
2095	}
2096	}
2097	}
2098	#endif
2099	setLastPC(pc);
2100	return true;
2101	}
2102	#endif
2103
2104	#if defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
2105	// Masks for traceback table field xtbtable.
2106	enum xTBTableMask : uint8_t {
2107	reservedBit = `0x02`, // The traceback table was incorrectly generated if set
2108	// (see comments in function getInfoFromTBTable().
2109	ehInfoBit = `0x08` // Exception handling info is present if set
2110	};
2111
2112	enum frameType : unw_word_t {
2113	frameWithXLEHStateTable = `0`,
2114	frameWithEHInfo = `1`
2115	};
2116
2117	extern "C" {
2118	typedef _Unwind_Reason_Code __xlcxx_personality_v0_t(int, _Unwind_Action,
2119	uint64_t,
2120	_Unwind_Exception *,
2121	struct _Unwind_Context *);
2122	}
2123
2124	static __xlcxx_personality_v0_t *xlcPersonalityV0;
2125	static RWMutex xlcPersonalityV0InitLock;
2126
2127	template <typename A, typename R>
2128	bool UnwindCursor<A, R>::getInfoFromTBTable(pint_t pc, R &registers) {
2129	uint32_t p = reinterpret_cast<uint32_t >(pc);
2130
2131	// Keep looking forward until a word of 0 is found. The traceback
2132	// table starts at the following word.
2133	while (*p)
2134	++p;
2135	tbtable TBTable = reinterpret_cast<tbtable >(p + `1`);
2136
2137	if (_LIBUNWIND_TRACING_UNWINDING) {
2138	char functionBuf[`512`];
2139	const char *functionName = functionBuf;
2140	unw_word_t offset;
2141	if (!getFunctionName(functionBuf, sizeof(functionBuf), &offset)) {
2142	functionName = ".anonymous.";
2143	}
2144	_LIBUNWIND_TRACE_UNWINDING("%s: Look up traceback table of func=%s at %p",
2145	__func__, functionName,
2146	reinterpret_cast<void *>(TBTable));
2147	}
2148
2149	// If the traceback table does not contain necessary info, bypass this frame.
2150	if (!TBTable->tb.has_tboff)
2151	return false;
2152
2153	// Structure tbtable_ext contains important data we are looking for.
2154	p = reinterpret_cast<uint32_t *>(&TBTable->tb_ext);
2155
2156	// Skip field parminfo if it exists.
2157	if (TBTable->tb.fixedparms \|\| TBTable->tb.floatparms)
2158	++p;
2159
2160	// p now points to tb_offset, the offset from start of function to TB table.
2161	unw_word_t start_ip =
2162	reinterpret_cast<unw_word_t>(TBTable) - p - sizeof*(uint32_t);
2163	unw_word_t end_ip = reinterpret_cast<unw_word_t>(TBTable);
2164	++p;
2165
2166	_LIBUNWIND_TRACE_UNWINDING("start_ip=%p, end_ip=%p\n",
2167	reinterpret_cast<void *>(start_ip),
2168	reinterpret_cast<void *>(end_ip));
2169
2170	// Skip field hand_mask if it exists.
2171	if (TBTable->tb.int_hndl)
2172	++p;
2173
2174	unw_word_t lsda = `0`;
2175	unw_word_t handler = `0`;
2176	unw_word_t flags = frameType::frameWithXLEHStateTable;
2177
2178	if (TBTable->tb.lang == TB_CPLUSPLUS && TBTable->tb.has_ctl) {
2179	// State table info is available. The ctl_info field indicates the
2180	// number of CTL anchors. There should be only one entry for the C++
2181	// state table.
2182	assert(*p == `1` && "libunwind: there must be only one ctl_info entry");
2183	++p;
2184	// p points to the offset of the state table into the stack.
2185	pint_t stateTableOffset = *p++;
2186
2187	int framePointerReg;
2188
2189	// Skip fields name_len and name if exist.
2190	if (TBTable->tb.name_present) {
2191	const uint16_t name_len = (reinterpret_cast<uint16_t >(p));
2192	p = reinterpret_cast<uint32_t >(reinterpret_cast<char* *>(p) + name_len +
2193	sizeof(uint16_t));
2194	}
2195
2196	if (TBTable->tb.uses_alloca)
2197	framePointerReg = (reinterpret_cast<char* *>(p));
2198	else
2199	framePointerReg = `1`; // default frame pointer == SP
2200
2201	_LIBUNWIND_TRACE_UNWINDING(
2202	"framePointerReg=%d, framePointer=%p, "
2203	"stateTableOffset=%#lx\n",
2204	framePointerReg,
2205	reinterpret_cast<void *>(_registers.getRegister(framePointerReg)),
2206	stateTableOffset);
2207	lsda = _registers.getRegister(framePointerReg) + stateTableOffset;
2208
2209	// Since the traceback table generated by the legacy XLC++ does not
2210	// provide the location of the personality for the state table,
2211	// function __xlcxx_personality_v0(), which is the personality for the state
2212	// table and is exported from libc++abi, is directly assigned as the
2213	// handler here. When a legacy XLC++ frame is encountered, the symbol
2214	// is resolved dynamically using dlopen() to avoid a hard dependency of
2215	// libunwind on libc++abi in cases such as non-C++ applications.
2216
2217	// Resolve the function pointer to the state table personality if it has
2218	// not already been done.
2219	if (xlcPersonalityV0 == NULL) {
2220	xlcPersonalityV0InitLock.lock();
2221	if (xlcPersonalityV0 == NULL) {
2222	// Resolve __xlcxx_personality_v0 using dlopen().
2223	const char *libcxxabi = "libc++abi.a(libc++abi.so.1)";
2224	void *libHandle;
2225	// The AIX dlopen() sets errno to 0 when it is successful, which
2226	// clobbers the value of errno from the user code. This is an AIX
2227	// bug because according to POSIX it should not set errno to 0. To
2228	// workaround before AIX fixes the bug, errno is saved and restored.
2229	int saveErrno = errno;
2230	libHandle = dlopen(libcxxabi, RTLD_MEMBER \| RTLD_NOW);
2231	if (libHandle == NULL) {
2232	_LIBUNWIND_TRACE_UNWINDING("dlopen() failed with errno=%d\n", errno);
2233	assert(`0` && "dlopen() failed");
2234	}
2235	xlcPersonalityV0 = reinterpret_cast<__xlcxx_personality_v0_t *>(
2236	dlsym(libHandle, "__xlcxx_personality_v0"));
2237	if (xlcPersonalityV0 == NULL) {
2238	_LIBUNWIND_TRACE_UNWINDING("dlsym() failed with errno=%d\n", errno);
2239	dlclose(libHandle);
2240	assert(`0` && "dlsym() failed");
2241	}
2242	errno = saveErrno;
2243	}
2244	xlcPersonalityV0InitLock.unlock();
2245	}
2246	handler = reinterpret_cast<unw_word_t>(xlcPersonalityV0);
2247	_LIBUNWIND_TRACE_UNWINDING("State table: LSDA=%p, Personality=%p\n",
2248	reinterpret_cast<void *>(lsda),
2249	reinterpret_cast<void *>(handler));
2250	} else if (TBTable->tb.longtbtable) {
2251	// This frame has the traceback table extension. Possible cases are
2252	// 1) a C++ frame that has the 'eh_info' structure; 2) a C++ frame that
2253	// is not EH aware; or, 3) a frame of other languages. We need to figure out
2254	// if the traceback table extension contains the 'eh_info' structure.
2255	//
2256	// We also need to deal with the complexity arising from some XL compiler
2257	// versions use the wrong ordering of 'longtbtable' and 'has_vec' bits
2258	// where the 'longtbtable' bit is meant to be the 'has_vec' bit and vice
2259	// versa. For frames of code generated by those compilers, the 'longtbtable'
2260	// bit may be set but there isn't really a traceback table extension.
2261	//
2262	// In </usr/include/sys/debug.h>, there is the following definition of
2263	// 'struct tbtable_ext'. It is not really a structure but a dummy to
2264	// collect the description of optional parts of the traceback table.
2265	//
2266	// struct tbtable_ext {
2267	// ...
2268	// char alloca_reg; / Register for alloca automatic storage /
2269	// struct vec_ext vec_ext; / Vector extension (if has_vec is set) /
2270	// unsigned char xtbtable; / More tbtable fields, if longtbtable is set/
2271	// };
2272	//
2273	// Depending on how the 'has_vec'/'longtbtable' bit is interpreted, the data
2274	// following 'alloca_reg' can be treated either as 'struct vec_ext' or
2275	// 'unsigned char xtbtable'. 'xtbtable' bits are defined in
2276	// </usr/include/sys/debug.h> as flags. The 7th bit '0x02' is currently
2277	// unused and should not be set. 'struct vec_ext' is defined in
2278	// </usr/include/sys/debug.h> as follows:
2279	//
2280	// struct vec_ext {
2281	// unsigned vr_saved:6; / Number of non-volatile vector regs saved*
2282	// /*
2283	// / first register saved is assumed to be /
2284	// / 32 - vr_saved /
2285	// unsigned saves_vrsave:1; / Set if vrsave is saved on the stack /
2286	// unsigned has_varargs:1;
2287	// ...
2288	// };
2289	//
2290	// Here, the 7th bit is used as 'saves_vrsave'. To determine whether it
2291	// is 'struct vec_ext' or 'xtbtable' that follows 'alloca_reg',
2292	// we checks if the 7th bit is set or not because 'xtbtable' should
2293	// never have the 7th bit set. The 7th bit of 'xtbtable' will be reserved
2294	// in the future to make sure the mitigation works. This mitigation
2295	// is not 100% bullet proof because 'struct vec_ext' may not always have
2296	// 'saves_vrsave' bit set.
2297	//
2298	// 'reservedBit' is defined in enum 'xTBTableMask' above as the mask for
2299	// checking the 7th bit.
2300
2301	// p points to field name len.
2302	uint8_t charPtr = reinterpret_cast<uint8_t >(p);
2303
2304	// Skip fields name_len and name if they exist.
2305	if (TBTable->tb.name_present) {
2306	const uint16_t name_len = (reinterpret_cast<uint16_t >(charPtr));
2307	charPtr = charPtr + name_len + sizeof(uint16_t);
2308	}
2309
2310	// Skip field alloc_reg if it exists.
2311	if (TBTable->tb.uses_alloca)
2312	++charPtr;
2313
2314	// Check traceback table bit has_vec. Skip struct vec_ext if it exists.
2315	if (TBTable->tb.has_vec)
2316	// Note struct vec_ext does exist at this point because whether the
2317	// ordering of longtbtable and has_vec bits is correct or not, both
2318	// are set.
2319	charPtr += sizeof(struct vec_ext);
2320
2321	// charPtr points to field 'xtbtable'. Check if the EH info is available.
2322	// Also check if the reserved bit of the extended traceback table field
2323	// 'xtbtable' is set. If it is, the traceback table was incorrectly
2324	// generated by an XL compiler that uses the wrong ordering of 'longtbtable'
2325	// and 'has_vec' bits and this is in fact 'struct vec_ext'. So skip the
2326	// frame.
2327	if ((*charPtr & xTBTableMask::ehInfoBit) &&
2328	!(*charPtr & xTBTableMask::reservedBit)) {
2329	// Mark this frame has the new EH info.
2330	flags = frameType::frameWithEHInfo;
2331
2332	// eh_info is available.
2333	charPtr++;
2334	// The pointer is 4-byte aligned.
2335	if (reinterpret_cast<uintptr_t>(charPtr) % `4`)
2336	charPtr += `4` - reinterpret_cast<uintptr_t>(charPtr) % `4`;
2337	uintptr_t *ehInfo =
2338	reinterpret_cast<uintptr_t >((reinterpret_cast<uintptr_t *>(
2339	registers.getRegister(`2`) +
2340	(reinterpret_cast<uintptr_t >(charPtr)))));
2341
2342	// ehInfo points to structure en_info. The first member is version.
2343	// Only version 0 is currently supported.
2344	assert((reinterpret_cast<uint32_t >(ehInfo)) == `0` &&
2345	"libunwind: ehInfo version other than 0 is not supported");
2346
2347	// Increment ehInfo to point to member lsda.
2348	++ehInfo;
2349	lsda = *ehInfo++;
2350
2351	// enInfo now points to member personality.
2352	handler = *ehInfo;
2353
2354	_LIBUNWIND_TRACE_UNWINDING("Range table: LSDA=%#lx, Personality=%#lx\n",
2355	lsda, handler);
2356	}
2357	}
2358
2359	_info.start_ip = start_ip;
2360	_info.end_ip = end_ip;
2361	_info.lsda = lsda;
2362	_info.handler = handler;
2363	_info.gp = `0`;
2364	_info.flags = flags;
2365	_info.format = `0`;
2366	_info.unwind_info = reinterpret_cast<unw_word_t>(TBTable);
2367	_info.unwind_info_size = `0`;
2368	_info.extra = registers.getRegister(`2`);
2369
2370	return true;
2371	}
2372
2373	// Step back up the stack following the frame back link.
2374	template <typename A, typename R>
2375	int UnwindCursor<A, R>::stepWithTBTable(pint_t pc, tbtable *TBTable,
2376	R &registers, bool &isSignalFrame) {
2377	if (_LIBUNWIND_TRACING_UNWINDING) {
2378	char functionBuf[`512`];
2379	const char *functionName = functionBuf;
2380	unw_word_t offset;
2381	if (!getFunctionName(functionBuf, sizeof(functionBuf), &offset)) {
2382	functionName = ".anonymous.";
2383	}
2384	_LIBUNWIND_TRACE_UNWINDING(
2385	"%s: Look up traceback table of func=%s at %p, pc=%p, "
2386	"SP=%p, saves_lr=%d, stores_bc=%d",
2387	__func__, functionName, reinterpret_cast<void *>(TBTable),
2388	reinterpret_cast<void *>(pc),
2389	reinterpret_cast<void *>(registers.getSP()), TBTable->tb.saves_lr,
2390	TBTable->tb.stores_bc);
2391	}
2392
2393	#if defined(__powerpc64__)
2394	// Instruction to reload TOC register "ld r2,40(r1)"
2395	const uint32_t loadTOCRegInst = `0xe8410028`;
2396	const int32_t unwPPCF0Index = UNW_PPC64_F0;
2397	const int32_t unwPPCV0Index = UNW_PPC64_V0;
2398	#else
2399	// Instruction to reload TOC register "lwz r2,20(r1)"
2400	const uint32_t loadTOCRegInst = `0x80410014`;
2401	const int32_t unwPPCF0Index = UNW_PPC_F0;
2402	const int32_t unwPPCV0Index = UNW_PPC_V0;
2403	#endif
2404
2405	// lastStack points to the stack frame of the next routine up.
2406	pint_t curStack = static_cast<pint_t>(registers.getSP());
2407	pint_t lastStack = *reinterpret_cast<pint_t *>(curStack);
2408
2409	if (lastStack == `0`)
2410	return UNW_STEP_END;
2411
2412	R newRegisters = registers;
2413
2414	// If backchain is not stored, use the current stack frame.
2415	if (!TBTable->tb.stores_bc)
2416	lastStack = curStack;
2417
2418	// Return address is the address after call site instruction.
2419	pint_t returnAddress;
2420
2421	if (isSignalFrame) {
2422	_LIBUNWIND_TRACE_UNWINDING("Possible signal handler frame: lastStack=%p",
2423	reinterpret_cast<void *>(lastStack));
2424
2425	sigcontext sigContext = reinterpret_cast<sigcontext >(
2426	reinterpret_cast<char *>(lastStack) + STKMINALIGN);
2427	returnAddress = sigContext->sc_jmpbuf.jmp_context.iar;
2428
2429	bool useSTKMIN = false;
2430	if (returnAddress < `0x10000000`) {
2431	// Try again using STKMIN.
2432	sigContext = reinterpret_cast<sigcontext *>(
2433	reinterpret_cast<char *>(lastStack) + STKMIN);
2434	returnAddress = sigContext->sc_jmpbuf.jmp_context.iar;
2435	if (returnAddress < `0x10000000`) {
2436	_LIBUNWIND_TRACE_UNWINDING("Bad returnAddress=%p from sigcontext=%p",
2437	reinterpret_cast<void *>(returnAddress),
2438	reinterpret_cast<void *>(sigContext));
2439	return UNW_EBADFRAME;
2440	}
2441	useSTKMIN = true;
2442	}
2443	_LIBUNWIND_TRACE_UNWINDING("Returning from a signal handler %s: "
2444	"sigContext=%p, returnAddress=%p. "
2445	"Seems to be a valid address",
2446	useSTKMIN ? "STKMIN" : "STKMINALIGN",
2447	reinterpret_cast<void *>(sigContext),
2448	reinterpret_cast<void *>(returnAddress));
2449
2450	// Restore the condition register from sigcontext.
2451	newRegisters.setCR(sigContext->sc_jmpbuf.jmp_context.cr);
2452
2453	// Save the LR in sigcontext for stepping up when the function that
2454	// raised the signal is a leaf function. This LR has the return address
2455	// to the caller of the leaf function.
2456	newRegisters.setLR(sigContext->sc_jmpbuf.jmp_context.lr);
2457	_LIBUNWIND_TRACE_UNWINDING(
2458	"Save LR=%p from sigcontext",
2459	reinterpret_cast<void *>(sigContext->sc_jmpbuf.jmp_context.lr));
2460
2461	// Restore GPRs from sigcontext.
2462	for (int i = `0`; i < `32`; ++i)
2463	newRegisters.setRegister(i, sigContext->sc_jmpbuf.jmp_context.gpr[i]);
2464
2465	// Restore FPRs from sigcontext.
2466	for (int i = `0`; i < `32`; ++i)
2467	newRegisters.setFloatRegister(i + unwPPCF0Index,
2468	sigContext->sc_jmpbuf.jmp_context.fpr[i]);
2469
2470	// Restore vector registers if there is an associated extended context
2471	// structure.
2472	if (sigContext->sc_jmpbuf.jmp_context.msr & __EXTCTX) {
2473	ucontext_t uContext = reinterpret_cast<ucontext_t >(sigContext);
2474	if (uContext->__extctx->__extctx_magic == __EXTCTX_MAGIC) {
2475	for (int i = `0`; i < `32`; ++i)
2476	newRegisters.setVectorRegister(
2477	i + unwPPCV0Index, (reinterpret_cast<v128 >(
2478	&(uContext->__extctx->__vmx.__vr[i]))));
2479	}
2480	}
2481	} else {
2482	// Step up a normal frame.
2483
2484	if (!TBTable->tb.saves_lr && registers.getLR()) {
2485	// This case should only occur if we were called from a signal handler
2486	// and the signal occurred in a function that doesn't save the LR.
2487	returnAddress = static_cast<pint_t>(registers.getLR());
2488	_LIBUNWIND_TRACE_UNWINDING("Use saved LR=%p",
2489	reinterpret_cast<void *>(returnAddress));
2490	} else {
2491	// Otherwise, use the LR value in the stack link area.
2492	returnAddress = reinterpret_cast<pint_t *>(lastStack)[`2`];
2493	}
2494
2495	// Reset LR in the current context.
2496	newRegisters.setLR(static_cast<uintptr_t>(NULL));
2497
2498	_LIBUNWIND_TRACE_UNWINDING(
2499	"Extract info from lastStack=%p, returnAddress=%p",
2500	reinterpret_cast<void *>(lastStack),
2501	reinterpret_cast<void *>(returnAddress));
2502	_LIBUNWIND_TRACE_UNWINDING("fpr_regs=%d, gpr_regs=%d, saves_cr=%d",
2503	TBTable->tb.fpr_saved, TBTable->tb.gpr_saved,
2504	TBTable->tb.saves_cr);
2505
2506	// Restore FP registers.
2507	char ptrToRegs = reinterpret_cast<char* *>(lastStack);
2508	double FPRegs = reinterpret_cast<double* *>(
2509	ptrToRegs - (TBTable->tb.fpr_saved * sizeof(double)));
2510	for (int i = `0`; i < TBTable->tb.fpr_saved; ++i)
2511	newRegisters.setFloatRegister(
2512	`32` - TBTable->tb.fpr_saved + i + unwPPCF0Index, FPRegs[i]);
2513
2514	// Restore GP registers.
2515	ptrToRegs = reinterpret_cast<char *>(FPRegs);
2516	uintptr_t GPRegs = reinterpret_cast<uintptr_t >(
2517	ptrToRegs - (TBTable->tb.gpr_saved * sizeof(uintptr_t)));
2518	for (int i = `0`; i < TBTable->tb.gpr_saved; ++i)
2519	newRegisters.setRegister(`32` - TBTable->tb.gpr_saved + i, GPRegs[i]);
2520
2521	// Restore Vector registers.
2522	ptrToRegs = reinterpret_cast<char *>(GPRegs);
2523
2524	// Restore vector registers only if this is a Clang frame. Also
2525	// check if traceback table bit has_vec is set. If it is, structure
2526	// vec_ext is available.
2527	if (_info.flags == frameType::frameWithEHInfo && TBTable->tb.has_vec) {
2528
2529	// Get to the vec_ext structure to check if vector registers are saved.
2530	uint32_t p = reinterpret_cast<uint32_t >(&TBTable->tb_ext);
2531
2532	// Skip field parminfo if exists.
2533	if (TBTable->tb.fixedparms \|\| TBTable->tb.floatparms)
2534	++p;
2535
2536	// Skip field tb_offset if exists.
2537	if (TBTable->tb.has_tboff)
2538	++p;
2539
2540	// Skip field hand_mask if exists.
2541	if (TBTable->tb.int_hndl)
2542	++p;
2543
2544	// Skip fields ctl_info and ctl_info_disp if exist.
2545	if (TBTable->tb.has_ctl) {
2546	// Skip field ctl_info.
2547	++p;
2548	// Skip field ctl_info_disp.
2549	++p;
2550	}
2551
2552	// Skip fields name_len and name if exist.
2553	// p is supposed to point to field name_len now.
2554	uint8_t charPtr = reinterpret_cast<uint8_t >(p);
2555	if (TBTable->tb.name_present) {
2556	const uint16_t name_len = (reinterpret_cast<uint16_t >(charPtr));
2557	charPtr = charPtr + name_len + sizeof(uint16_t);
2558	}
2559
2560	// Skip field alloc_reg if it exists.
2561	if (TBTable->tb.uses_alloca)
2562	++charPtr;
2563
2564	struct vec_ext vec_ext = reinterpret_cast<struct* vec_ext *>(charPtr);
2565
2566	_LIBUNWIND_TRACE_UNWINDING("vr_saved=%d", vec_ext->vr_saved);
2567
2568	// Restore vector register(s) if saved on the stack.
2569	if (vec_ext->vr_saved) {
2570	// Saved vector registers are 16-byte aligned.
2571	if (reinterpret_cast<uintptr_t>(ptrToRegs) % `16`)
2572	ptrToRegs -= reinterpret_cast<uintptr_t>(ptrToRegs) % `16`;
2573	v128 VecRegs = reinterpret_cast<v128 >(ptrToRegs - vec_ext->vr_saved *
2574	sizeof(v128));
2575	for (int i = `0`; i < vec_ext->vr_saved; ++i) {
2576	newRegisters.setVectorRegister(
2577	`32` - vec_ext->vr_saved + i + unwPPCV0Index, VecRegs[i]);
2578	}
2579	}
2580	}
2581	if (TBTable->tb.saves_cr) {
2582	// Get the saved condition register. The condition register is only
2583	// a single word.
2584	newRegisters.setCR(
2585	(reinterpret_cast<uint32_t >(lastStack + sizeof(uintptr_t))));
2586	}
2587
2588	// Restore the SP.
2589	newRegisters.setSP(lastStack);
2590
2591	// The first instruction after return.
2592	uint32_t firstInstruction = (reinterpret_cast<uint32_t >(returnAddress));
2593
2594	// Do we need to set the TOC register?
2595	_LIBUNWIND_TRACE_UNWINDING(
2596	"Current gpr2=%p",
2597	reinterpret_cast<void *>(newRegisters.getRegister(`2`)));
2598	if (firstInstruction == loadTOCRegInst) {
2599	_LIBUNWIND_TRACE_UNWINDING(
2600	"Set gpr2=%p from frame",
2601	reinterpret_cast<void >(reinterpret_cast<pint_t >(lastStack)[`5`]));
2602	newRegisters.setRegister(`2`, reinterpret_cast<pint_t *>(lastStack)[`5`]);
2603	}
2604	}
2605	_LIBUNWIND_TRACE_UNWINDING("lastStack=%p, returnAddress=%p, pc=%p\n",
2606	reinterpret_cast<void *>(lastStack),
2607	reinterpret_cast<void *>(returnAddress),
2608	reinterpret_cast<void *>(pc));
2609
2610	// The return address is the address after call site instruction, so
2611	// setting IP to that simulates a return.
2612	newRegisters.setIP(reinterpret_cast<uintptr_t>(returnAddress));
2613
2614	// Simulate the step by replacing the register set with the new ones.
2615	registers = newRegisters;
2616
2617	// Check if the next frame is a signal frame.
2618	pint_t nextStack = (reinterpret_cast<pint_t >(registers.getSP()));
2619
2620	// Return address is the address after call site instruction.
2621	pint_t nextReturnAddress = reinterpret_cast<pint_t *>(nextStack)[`2`];
2622
2623	if (nextReturnAddress > `0x01` && nextReturnAddress < `0x10000`) {
2624	_LIBUNWIND_TRACE_UNWINDING("The next is a signal handler frame: "
2625	"nextStack=%p, next return address=%p\n",
2626	reinterpret_cast<void *>(nextStack),
2627	reinterpret_cast<void *>(nextReturnAddress));
2628	isSignalFrame = true;
2629	} else {
2630	isSignalFrame = false;
2631	}
2632	return UNW_STEP_SUCCESS;
2633	}
2634	#endif // defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
2635
2636	template <typename A, typename R>
2637	void UnwindCursor<A, R>::setInfoBasedOnIPRegister(bool isReturnAddress) {
2638	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) \|\| \
2639	defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
2640	_isSigReturn = false;
2641	#endif
2642
2643	pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
2644	#if defined(_LIBUNWIND_ARM_EHABI)
2645	// Remove the thumb bit so the IP represents the actual instruction address.
2646	// This matches the behaviour of _Unwind_GetIP on arm.
2647	pc &= (pint_t)~`0x1`;
2648	#endif
2649
2650	// Exit early if at the top of the stack.
2651	if (pc == `0`) {
2652	_unwindInfoMissing = true;
2653	return;
2654	}
2655
2656	// If the last line of a function is a "throw" the compiler sometimes
2657	// emits no instructions after the call to __cxa_throw. This means
2658	// the return address is actually the start of the next function.
2659	// To disambiguate this, back up the pc when we know it is a return
2660	// address.
2661	if (isReturnAddress)
2662	#if defined(_AIX)
2663	// PC needs to be a 4-byte aligned address to be able to look for a
2664	// word of 0 that indicates the start of the traceback table at the end
2665	// of a function on AIX.
2666	pc -= `4`;
2667	#else
2668	--pc;
2669	#endif
2670
2671	#if !(defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) && defined(_WIN32)) && \
2672	!defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
2673	// In case of this is frame of signal handler, the IP saved in the signal
2674	// handler points to first non-executed instruction, while FDE/CIE expects IP
2675	// to be after the first non-executed instruction.
2676	if (_isSignalFrame)
2677	++pc;
2678	#endif
2679
2680	// Ask address space object to find unwind sections for this pc.
2681	UnwindInfoSections sects;
2682	if (_addressSpace.findUnwindSections(pc, sects)) {
2683	#if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
2684	// If there is a compact unwind encoding table, look there first.
2685	if (sects.compact_unwind_section != `0`) {
2686	if (this->getInfoFromCompactEncodingSection(pc, sects)) {
2687	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
2688	// Found info in table, done unless encoding says to use dwarf.
2689	uint32_t dwarfOffset;
2690	if ((sects.dwarf_section != `0`) && compactSaysUseDwarf(&dwarfOffset)) {
2691	if (this->getInfoFromDwarfSection(pc, sects, dwarfOffset)) {
2692	// found info in dwarf, done
2693	return;
2694	}
2695	}
2696	#endif
2697	// If unwind table has entry, but entry says there is no unwind info,
2698	// record that we have no unwind info.
2699	if (_info.format == `0`)
2700	_unwindInfoMissing = true;
2701	return;
2702	}
2703	}
2704	#endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
2705
2706	#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
2707	// If there is SEH unwind info, look there next.
2708	if (this->getInfoFromSEH(pc))
2709	return;
2710	#endif
2711
2712	#if defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
2713	// If there is unwind info in the traceback table, look there next.
2714	if (this->getInfoFromTBTable(pc, _registers))
2715	return;
2716	#endif
2717
2718	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
2719	// If there is dwarf unwind info, look there next.
2720	if (sects.dwarf_section != `0`) {
2721	if (this->getInfoFromDwarfSection(pc, sects)) {
2722	// found info in dwarf, done
2723	return;
2724	}
2725	}
2726	#endif
2727
2728	#if defined(_LIBUNWIND_ARM_EHABI)
2729	// If there is ARM EHABI unwind info, look there next.
2730	if (sects.arm_section != `0` && this->getInfoFromEHABISection(pc, sects))
2731	return;
2732	#endif
2733	}
2734
2735	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
2736	// There is no static unwind info for this pc. Look to see if an FDE was
2737	// dynamically registered for it.
2738	pint_t cachedFDE = DwarfFDECache<A>::findFDE(DwarfFDECache<A>::kSearchAll,
2739	pc);
2740	if (cachedFDE != `0`) {
2741	typename CFI_Parser<A>::FDE_Info fdeInfo;
2742	typename CFI_Parser<A>::CIE_Info cieInfo;
2743	if (!CFI_Parser<A>::decodeFDE(_addressSpace, cachedFDE, &fdeInfo, &cieInfo))
2744	if (getInfoFromFdeCie(fdeInfo, cieInfo, pc, dso_base: `0`))
2745	return;
2746	}
2747
2748	// Lastly, ask AddressSpace object about platform specific ways to locate
2749	// other FDEs.
2750	pint_t fde;
2751	if (_addressSpace.findOtherFDE(pc, fde)) {
2752	typename CFI_Parser<A>::FDE_Info fdeInfo;
2753	typename CFI_Parser<A>::CIE_Info cieInfo;
2754	if (!CFI_Parser<A>::decodeFDE(_addressSpace, fde, &fdeInfo, &cieInfo)) {
2755	// Double check this FDE is for a function that includes the pc.
2756	if ((fdeInfo.pcStart <= pc) && (pc < fdeInfo.pcEnd))
2757	if (getInfoFromFdeCie(fdeInfo, cieInfo, pc, dso_base: `0`))
2758	return;
2759	}
2760	}
2761	#endif // #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
2762
2763	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) \|\| \
2764	defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
2765	if (setInfoForSigReturn())
2766	return;
2767	#endif
2768
2769	// no unwind info, flag that we can't reliably unwind
2770	_unwindInfoMissing = true;
2771	}
2772
2773	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) && \
2774	defined(_LIBUNWIND_TARGET_AARCH64)
2775	template <typename A, typename R>
2776	bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_arm64 &) {
2777	// Look for the sigreturn trampoline. The trampoline's body is two
2778	// specific instructions (see below). Typically the trampoline comes from the
2779	// vDSO[1] (i.e. the __kernel_rt_sigreturn function). A libc might provide its
2780	// own restorer function, though, or user-mode QEMU might write a trampoline
2781	// onto the stack.
2782	//
2783	// This special code path is a fallback that is only used if the trampoline
2784	// lacks proper (e.g. DWARF) unwind info. On AArch64, a new DWARF register
2785	// constant for the PC needs to be defined before DWARF can handle a signal
2786	// trampoline. This code may segfault if the target PC is unreadable, e.g.:
2787	// - The PC points at a function compiled without unwind info, and which is
2788	// part of an execute-only mapping (e.g. using -Wl,--execute-only).
2789	// - The PC is invalid and happens to point to unreadable or unmapped memory.
2790	//
2791	// [1] https://github.com/torvalds/linux/blob/master/arch/arm64/kernel/vdso/sigreturn.S
2792	const pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
2793	// The PC might contain an invalid address if the unwind info is bad, so
2794	// directly accessing it could cause a SIGSEGV.
2795	if (!isReadableAddr(pc))
2796	return false;
2797	auto instructions = reinterpret_cast<const* uint32_t *>(pc);
2798	// Look for instructions: mov x8, #0x8b; svc #0x0
2799	if (instructions[`0`] != `0xd2801168` \|\| instructions[`1`] != `0xd4000001`)
2800	return false;
2801
2802	_info = {};
2803	_info.start_ip = pc;
2804	_info.end_ip = pc + `4`;
2805	_isSigReturn = true;
2806	return true;
2807	}
2808
2809	template <typename A, typename R>
2810	int UnwindCursor<A, R>::stepThroughSigReturn(Registers_arm64 &) {
2811	// In the signal trampoline frame, sp points to an rt_sigframe[1], which is:
2812	// - 128-byte siginfo struct
2813	// - ucontext struct:
2814	// - 8-byte long (uc_flags)
2815	// - 8-byte pointer (uc_link)
2816	// - 24-byte stack_t
2817	// - 128-byte signal set
2818	// - 8 bytes of padding because sigcontext has 16-byte alignment
2819	// - sigcontext/mcontext_t
2820	// [1] https://github.com/torvalds/linux/blob/master/arch/arm64/kernel/signal.c
2821	const pint_t kOffsetSpToSigcontext = (`128` + `8` + `8` + `24` + `128` + `8`); // 304
2822
2823	// Offsets from sigcontext to each register.
2824	const pint_t kOffsetGprs = `8`; // offset to "__u64 regs[31]" field
2825	const pint_t kOffsetSp = `256`; // offset to "__u64 sp" field
2826	const pint_t kOffsetPc = `264`; // offset to "__u64 pc" field
2827
2828	pint_t sigctx = _registers.getSP() + kOffsetSpToSigcontext;
2829
2830	for (int i = `0`; i <= `30`; ++i) {
2831	uint64_t value = _addressSpace.get64(sigctx + kOffsetGprs +
2832	static_cast<pint_t>(i * `8`));
2833	_registers.setRegister(UNW_AARCH64_X0 + i, value);
2834	}
2835	_registers.setSP(_addressSpace.get64(sigctx + kOffsetSp));
2836	_registers.setIP(_addressSpace.get64(sigctx + kOffsetPc));
2837	_isSignalFrame = true;
2838	return UNW_STEP_SUCCESS;
2839	}
2840	#endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&
2841	// defined(_LIBUNWIND_TARGET_AARCH64)
2842
2843	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) && \
2844	defined(_LIBUNWIND_TARGET_LOONGARCH)
2845	template <typename A, typename R>
2846	bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_loongarch &) {
2847	const pint_t pc = static_cast<pint_t>(getReg(UNW_REG_IP));
2848	// The PC might contain an invalid address if the unwind info is bad, so
2849	// directly accessing it could cause a SIGSEGV.
2850	if (!isReadableAddr(pc))
2851	return false;
2852	const auto instructions = reinterpret_cast<const* uint32_t *>(pc);
2853	// Look for the two instructions used in the sigreturn trampoline
2854	// __vdso_rt_sigreturn:
2855	//
2856	// 0x03822c0b li a7,0x8b
2857	// 0x002b0000 syscall 0
2858	if (instructions[`0`] != `0x03822c0b` \|\| instructions[`1`] != `0x002b0000`)
2859	return false;
2860
2861	_info = {};
2862	_info.start_ip = pc;
2863	_info.end_ip = pc + `4`;
2864	_isSigReturn = true;
2865	return true;
2866	}
2867
2868	template <typename A, typename R>
2869	int UnwindCursor<A, R>::stepThroughSigReturn(Registers_loongarch &) {
2870	// In the signal trampoline frame, sp points to an rt_sigframe[1], which is:
2871	// - 128-byte siginfo struct
2872	// - ucontext_t struct:
2873	// - 8-byte long (__uc_flags)
2874	// - 8-byte pointer (uc_link)*
2875	// - 24-byte uc_stack
2876	// - 8-byte uc_sigmask
2877	// - 120-byte of padding to allow sigset_t to be expanded in the future
2878	// - 8 bytes of padding because sigcontext has 16-byte alignment
2879	// - struct sigcontext uc_mcontext
2880	// [1]
2881	// https://github.com/torvalds/linux/blob/master/arch/loongarch/kernel/signal.c
2882	const pint_t kOffsetSpToSigcontext = `128` + `8` + `8` + `24` + `8` + `128`;
2883
2884	const pint_t sigctx = _registers.getSP() + kOffsetSpToSigcontext;
2885	_registers.setIP(_addressSpace.get64(sigctx));
2886	for (int i = UNW_LOONGARCH_R1; i <= UNW_LOONGARCH_R31; ++i) {
2887	// skip R0
2888	uint64_t value =
2889	_addressSpace.get64(sigctx + static_cast<pint_t>((i + `1`) * `8`));
2890	_registers.setRegister(i, value);
2891	}
2892	_isSignalFrame = true;
2893	return UNW_STEP_SUCCESS;
2894	}
2895	#endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&
2896	// defined(_LIBUNWIND_TARGET_LOONGARCH)
2897
2898	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) && \
2899	defined(_LIBUNWIND_TARGET_RISCV)
2900	template <typename A, typename R>
2901	bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_riscv &) {
2902	const pint_t pc = static_cast<pint_t>(getReg(UNW_REG_IP));
2903	// The PC might contain an invalid address if the unwind info is bad, so
2904	// directly accessing it could cause a SIGSEGV.
2905	if (!isReadableAddr(pc))
2906	return false;
2907	const auto instructions = reinterpret_cast<const* uint32_t *>(pc);
2908	// Look for the two instructions used in the sigreturn trampoline
2909	// __vdso_rt_sigreturn:
2910	//
2911	// 0x08b00893 li a7,0x8b
2912	// 0x00000073 ecall
2913	if (instructions[`0`] != `0x08b00893` \|\| instructions[`1`] != `0x00000073`)
2914	return false;
2915
2916	_info = {};
2917	_info.start_ip = pc;
2918	_info.end_ip = pc + `4`;
2919	_isSigReturn = true;
2920	return true;
2921	}
2922
2923	template <typename A, typename R>
2924	int UnwindCursor<A, R>::stepThroughSigReturn(Registers_riscv &) {
2925	// In the signal trampoline frame, sp points to an rt_sigframe[1], which is:
2926	// - 128-byte siginfo struct
2927	// - ucontext_t struct:
2928	// - 8-byte long (__uc_flags)
2929	// - 8-byte pointer (uc_link)*
2930	// - 24-byte uc_stack
2931	// - 8-byte uc_sigmask
2932	// - 120-byte of padding to allow sigset_t to be expanded in the future
2933	// - 8 bytes of padding because sigcontext has 16-byte alignment
2934	// - struct sigcontext uc_mcontext
2935	// [1]
2936	// https://github.com/torvalds/linux/blob/master/arch/riscv/kernel/signal.c
2937	const pint_t kOffsetSpToSigcontext = `128` + `8` + `8` + `24` + `8` + `128`;
2938
2939	const pint_t sigctx = _registers.getSP() + kOffsetSpToSigcontext;
2940	_registers.setIP(_addressSpace.get64(sigctx));
2941	for (int i = UNW_RISCV_X1; i <= UNW_RISCV_X31; ++i) {
2942	uint64_t value = _addressSpace.get64(sigctx + static_cast<pint_t>(i * `8`));
2943	_registers.setRegister(i, value);
2944	}
2945	_isSignalFrame = true;
2946	return UNW_STEP_SUCCESS;
2947	}
2948	#endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&
2949	// defined(_LIBUNWIND_TARGET_RISCV)
2950
2951	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) && \
2952	defined(_LIBUNWIND_TARGET_S390X)
2953	template <typename A, typename R>
2954	bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_s390x &) {
2955	// Look for the sigreturn trampoline. The trampoline's body is a
2956	// specific instruction (see below). Typically the trampoline comes from the
2957	// vDSO (i.e. the __kernel_[rt_]sigreturn function). A libc might provide its
2958	// own restorer function, though, or user-mode QEMU might write a trampoline
2959	// onto the stack.
2960	const pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
2961	// The PC might contain an invalid address if the unwind info is bad, so
2962	// directly accessing it could cause a SIGSEGV.
2963	if (!isReadableAddr(pc))
2964	return false;
2965	const auto inst = *reinterpret_cast<const uint16_t *>(pc);
2966	if (inst == `0x0a77` \|\| inst == `0x0aad`) {
2967	_info = {};
2968	_info.start_ip = pc;
2969	_info.end_ip = pc + `2`;
2970	_isSigReturn = true;
2971	return true;
2972	}
2973	return false;
2974	}
2975
2976	template <typename A, typename R>
2977	int UnwindCursor<A, R>::stepThroughSigReturn(Registers_s390x &) {
2978	// Determine current SP.
2979	const pint_t sp = static_cast<pint_t>(this->getReg(UNW_REG_SP));
2980	// According to the s390x ABI, the CFA is at (incoming) SP + 160.
2981	const pint_t cfa = sp + `160`;
2982
2983	// Determine current PC and instruction there (this must be either
2984	// a "svc __NR_sigreturn" or "svc __NR_rt_sigreturn").
2985	const pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
2986	const uint16_t inst = _addressSpace.get16(pc);
2987
2988	// Find the addresses of the signo and sigcontext in the frame.
2989	pint_t pSigctx = `0`;
2990	pint_t pSigno = `0`;
2991
2992	// "svc __NR_sigreturn" uses a non-RT signal trampoline frame.
2993	if (inst == `0x0a77`) {
2994	// Layout of a non-RT signal trampoline frame, starting at the CFA:
2995	// - 8-byte signal mask
2996	// - 8-byte pointer to sigcontext, followed by signo
2997	// - 4-byte signo
2998	pSigctx = _addressSpace.get64(cfa + `8`);
2999	pSigno = pSigctx + `344`;
3000	}
3001
3002	// "svc __NR_rt_sigreturn" uses a RT signal trampoline frame.
3003	if (inst == `0x0aad`) {
3004	// Layout of a RT signal trampoline frame, starting at the CFA:
3005	// - 8-byte retcode (+ alignment)
3006	// - 128-byte siginfo struct (starts with signo)
3007	// - ucontext struct:
3008	// - 8-byte long (uc_flags)
3009	// - 8-byte pointer (uc_link)
3010	// - 24-byte stack_t
3011	// - 8 bytes of padding because sigcontext has 16-byte alignment
3012	// - sigcontext/mcontext_t
3013	pSigctx = cfa + `8` + `128` + `8` + `8` + `24` + `8`;
3014	pSigno = cfa + `8`;
3015	}
3016
3017	assert(pSigctx != `0`);
3018	assert(pSigno != `0`);
3019
3020	// Offsets from sigcontext to each register.
3021	const pint_t kOffsetPc = `8`;
3022	const pint_t kOffsetGprs = `16`;
3023	const pint_t kOffsetFprs = `216`;
3024
3025	// Restore all registers.
3026	for (int i = `0`; i < `16`; ++i) {
3027	uint64_t value = _addressSpace.get64(pSigctx + kOffsetGprs +
3028	static_cast<pint_t>(i * `8`));
3029	_registers.setRegister(UNW_S390X_R0 + i, value);
3030	}
3031	for (int i = `0`; i < `16`; ++i) {
3032	static const int fpr[`16`] = {
3033	UNW_S390X_F0, UNW_S390X_F1, UNW_S390X_F2, UNW_S390X_F3,
3034	UNW_S390X_F4, UNW_S390X_F5, UNW_S390X_F6, UNW_S390X_F7,
3035	UNW_S390X_F8, UNW_S390X_F9, UNW_S390X_F10, UNW_S390X_F11,
3036	UNW_S390X_F12, UNW_S390X_F13, UNW_S390X_F14, UNW_S390X_F15
3037	};
3038	double value = _addressSpace.getDouble(pSigctx + kOffsetFprs +
3039	static_cast<pint_t>(i * `8`));
3040	_registers.setFloatRegister(fpr[i], value);
3041	}
3042	_registers.setIP(_addressSpace.get64(pSigctx + kOffsetPc));
3043
3044	// SIGILL, SIGFPE and SIGTRAP are delivered with psw_addr
3045	// after the faulting instruction rather than before it.
3046	// Do not set _isSignalFrame in that case.
3047	uint32_t signo = _addressSpace.get32(pSigno);
3048	_isSignalFrame = (signo != `4` && signo != `5` && signo != `8`);
3049
3050	return UNW_STEP_SUCCESS;
3051	}
3052	#endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&
3053	// defined(_LIBUNWIND_TARGET_S390X)
3054
3055	#if defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
3056	template <typename A, typename R>
3057	bool UnwindCursor<A, R>::setInfoForSigReturn() {
3058	Dl_info dlinfo;
3059	const auto isSignalHandler = [&](pint_t addr) {
3060	if (!dladdr(reinterpret_cast<void *>(addr), &dlinfo))
3061	return false;
3062	if (strcmp(dlinfo.dli_fname, "commpage"))
3063	return false;
3064	if (dlinfo.dli_sname == NULL \|\|
3065	strcmp(dlinfo.dli_sname, "commpage_signal_handler"))
3066	return false;
3067	return true;
3068	};
3069
3070	pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
3071	if (!isSignalHandler(pc))
3072	return false;
3073
3074	pint_t start = reinterpret_cast<pint_t>(dlinfo.dli_saddr);
3075
3076	static size_t signalHandlerSize = `0`;
3077	if (signalHandlerSize == `0`) {
3078	size_t boundLow = `0`;
3079	size_t boundHigh = static_cast<size_t>(-`1`);
3080
3081	area_info areaInfo;
3082	if (get_area_info(area_for(dlinfo.dli_saddr), &areaInfo) == B_OK)
3083	boundHigh = areaInfo.size;
3084
3085	while (boundLow < boundHigh) {
3086	size_t boundMid = boundLow + ((boundHigh - boundLow) / `2`);
3087	pint_t test = start + boundMid;
3088	if (test >= start && isSignalHandler(test))
3089	boundLow = boundMid + `1`;
3090	else
3091	boundHigh = boundMid;
3092	}
3093
3094	signalHandlerSize = boundHigh;
3095	}
3096
3097	_info = {};
3098	_info.start_ip = start;
3099	_info.end_ip = start + signalHandlerSize;
3100	_isSigReturn = true;
3101
3102	return true;
3103	}
3104
3105	template <typename A, typename R>
3106	int UnwindCursor<A, R>::stepThroughSigReturn() {
3107	_isSignalFrame = true;
3108
3109	#if defined(_LIBUNWIND_TARGET_X86_64)
3110	// Layout of the stack before function call:
3111	// - signal_frame_data
3112	// + siginfo_t (public struct, fairly stable)
3113	// + ucontext_t (public struct, fairly stable)
3114	// - mcontext_t -> Offset 0x70, this is what we want.
3115	// - frame->ip (8 bytes)
3116	// - frame->bp (8 bytes). Not written by the kernel,
3117	// but the signal handler has a "push %rbp" instruction.
3118	pint_t bp = this->getReg(UNW_X86_64_RBP);
3119	vregs regs = (vregs )(bp + `0x70`);
3120
3121	_registers.setRegister(UNW_REG_IP, regs->rip);
3122	_registers.setRegister(UNW_REG_SP, regs->rsp);
3123	_registers.setRegister(UNW_X86_64_RAX, regs->rax);
3124	_registers.setRegister(UNW_X86_64_RDX, regs->rdx);
3125	_registers.setRegister(UNW_X86_64_RCX, regs->rcx);
3126	_registers.setRegister(UNW_X86_64_RBX, regs->rbx);
3127	_registers.setRegister(UNW_X86_64_RSI, regs->rsi);
3128	_registers.setRegister(UNW_X86_64_RDI, regs->rdi);
3129	_registers.setRegister(UNW_X86_64_RBP, regs->rbp);
3130	_registers.setRegister(UNW_X86_64_R8, regs->r8);
3131	_registers.setRegister(UNW_X86_64_R9, regs->r9);
3132	_registers.setRegister(UNW_X86_64_R10, regs->r10);
3133	_registers.setRegister(UNW_X86_64_R11, regs->r11);
3134	_registers.setRegister(UNW_X86_64_R12, regs->r12);
3135	_registers.setRegister(UNW_X86_64_R13, regs->r13);
3136	_registers.setRegister(UNW_X86_64_R14, regs->r14);
3137	_registers.setRegister(UNW_X86_64_R15, regs->r15);
3138	// TODO: XMM
3139	#endif // defined(_LIBUNWIND_TARGET_X86_64)
3140
3141	return UNW_STEP_SUCCESS;
3142	}
3143	#endif // defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
3144
3145	template <typename A, typename R> int UnwindCursor<A, R>::step(bool stage2) {
3146	(void)stage2;
3147	// Bottom of stack is defined is when unwind info cannot be found.
3148	if (_unwindInfoMissing)
3149	return UNW_STEP_END;
3150
3151	// Use unwinding info to modify register set as if function returned.
3152	int result;
3153	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) \|\| \
3154	defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
3155	if (_isSigReturn) {
3156	result = this->stepThroughSigReturn();
3157	} else
3158	#endif
3159	{
3160	#if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
3161	result = this->stepWithCompactEncoding(stage2);
3162	#elif defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
3163	result = this->stepWithSEHData();
3164	#elif defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
3165	result = this->stepWithTBTableData();
3166	#elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
3167	result = this->stepWithDwarfFDE(stage2);
3168	#elif defined(_LIBUNWIND_ARM_EHABI)
3169	result = this->stepWithEHABI();
3170	#else
3171	#error Need _LIBUNWIND_SUPPORT_COMPACT_UNWIND or \
3172	_LIBUNWIND_SUPPORT_SEH_UNWIND or \
3173	_LIBUNWIND_SUPPORT_DWARF_UNWIND or \
3174	_LIBUNWIND_ARM_EHABI
3175	#endif
3176	}
3177
3178	// update info based on new PC
3179	if (result == UNW_STEP_SUCCESS) {
3180	this->setInfoBasedOnIPRegister(true);
3181	if (_unwindInfoMissing)
3182	return UNW_STEP_END;
3183	}
3184
3185	return result;
3186	}
3187
3188	template <typename A, typename R>
3189	void UnwindCursor<A, R>::getInfo(unw_proc_info_t *info) {
3190	if (_unwindInfoMissing)
3191	memset(s: info, c: `0`, n: sizeof(*info));
3192	else
3193	*info = _info;
3194	}
3195
3196	template <typename A, typename R>
3197	bool UnwindCursor<A, R>::getFunctionName(char *buf, size_t bufLen,
3198	unw_word_t *offset) {
3199	return _addressSpace.findFunctionName((pint_t)this->getReg(UNW_REG_IP),
3200	buf, bufLen, offset);
3201	}
3202
3203	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN)
3204	template <typename A, typename R>
3205	bool UnwindCursor<A, R>::isReadableAddr(const pint_t addr) const {
3206	// We use SYS_rt_sigprocmask, inspired by Abseil's AddressIsReadable.
3207
3208	const auto sigsetAddr = reinterpret_cast<sigset_t *>(addr);
3209	// We have to check that addr is nullptr because sigprocmask allows that
3210	// as an argument without failure.
3211	if (!sigsetAddr)
3212	return false;
3213	const auto saveErrno = errno;
3214	// We MUST use a raw syscall here, as wrappers may try to access
3215	// sigsetAddr which may cause a SIGSEGV. A raw syscall however is
3216	// safe. Additionally, we need to pass the kernel_sigset_size, which is
3217	// different from libc sizeof(sigset_t). For the majority of architectures,
3218	// it's 64 bits (_NSIG), and libc NSIG is _NSIG + 1.
3219	const auto kernelSigsetSize = NSIG / `8`;
3220	[[maybe_unused]] const int Result = syscall(
3221	SYS_rt_sigprocmask, /how=/~`0`, sigsetAddr, nullptr, kernelSigsetSize);
3222	// Because our "how" is invalid, this syscall should always fail, and our
3223	// errno should always be EINVAL or an EFAULT. This relies on the Linux
3224	// kernel to check copy_from_user before checking if the "how" argument is
3225	// invalid.
3226	assert(Result == -`1`);
3227	assert(errno == EFAULT \|\| errno == EINVAL);
3228	const auto readable = errno != EFAULT;
3229	errno = saveErrno;
3230	return readable;
3231	}
3232	#endif
3233
3234	#if defined(_LIBUNWIND_USE_CET) \|\| defined(_LIBUNWIND_USE_GCS)
3235	extern "C" void __libunwind_shstk_get_registers(unw_cursor_t cursor) {
3236	AbstractUnwindCursor co = (AbstractUnwindCursor )cursor;
3237	return co->get_registers();
3238	}
3239	#endif
3240	} // namespace libunwind
3241
3242	#endif // __UNWINDCURSOR_HPP__
3243

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source code of libunwind/src/UnwindCursor.hpp