UnwindCursor.hpp source code [llvm_projects/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) && \
45	(defined(_LIBUNWIND_TARGET_I386) \|\| defined(_LIBUNWIND_TARGET_X86_64))
46	#include <OS.h>
47	#include <signal.h>
48	#define _LIBUNWIND_CHECK_HAIKU_SIGRETURN 1
49	#endif
50
51	#include "AddressSpace.hpp"
52	#include "CompactUnwinder.hpp"
53	#include "config.h"
54	#include "DwarfInstructions.hpp"
55	#include "EHHeaderParser.hpp"
56	#include "libunwind.h"
57	#include "libunwind_ext.h"
58	#include "Registers.hpp"
59	#include "RWMutex.hpp"
60	#include "Unwind-EHABI.h"
61
62	#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
63	// Provide a definition for the DISPATCHER_CONTEXT struct for old (Win7 and
64	// earlier) SDKs.
65	// MinGW-w64 has always provided this struct.
66	#if defined(_WIN32) && defined(_LIBUNWIND_TARGET_X86_64) && \
67	!defined(__MINGW32__) && VER_PRODUCTBUILD < 8000
68	struct _DISPATCHER_CONTEXT {
69	ULONG64 ControlPc;
70	ULONG64 ImageBase;
71	PRUNTIME_FUNCTION FunctionEntry;
72	ULONG64 EstablisherFrame;
73	ULONG64 TargetIp;
74	PCONTEXT ContextRecord;
75	PEXCEPTION_ROUTINE LanguageHandler;
76	PVOID HandlerData;
77	PUNWIND_HISTORY_TABLE HistoryTable;
78	ULONG ScopeIndex;
79	ULONG Fill0;
80	};
81	#endif
82
83	struct UNWIND_INFO {
84	uint8_t Version : `3`;
85	uint8_t Flags : `5`;
86	uint8_t SizeOfProlog;
87	uint8_t CountOfCodes;
88	uint8_t FrameRegister : `4`;
89	uint8_t FrameOffset : `4`;
90	uint16_t UnwindCodes[`2`];
91	};
92
93	#pragma clang diagnostic push
94	#pragma clang diagnostic ignored "-Wgnu-anonymous-struct"
95	union UNWIND_INFO_ARM {
96	DWORD HeaderData;
97	struct {
98	DWORD FunctionLength : `18`;
99	DWORD Version : `2`;
100	DWORD ExceptionDataPresent : `1`;
101	DWORD EpilogInHeader : `1`;
102	DWORD FunctionFragment : `1`;
103	DWORD EpilogCount : `5`;
104	DWORD CodeWords : `4`;
105	};
106	};
107	#pragma clang diagnostic pop
108
109	extern "C" _Unwind_Reason_Code __libunwind_seh_personality(
110	int, _Unwind_Action, uint64_t, _Unwind_Exception *,
111	struct _Unwind_Context *);
112
113	#endif
114
115	namespace libunwind {
116
117	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
118	/// Cache of recently found FDEs.
119	template <typename A>
120	class _LIBUNWIND_HIDDEN DwarfFDECache {
121	typedef typename A::pint_t pint_t;
122	public:
123	static constexpr pint_t kSearchAll = static_cast<pint_t>(-`1`);
124	template <typename R>
125	static pint_t findFDE(pint_t mh, typename R::link_hardened_reg_arg_t pc);
126
127	static void add(pint_t mh, pint_t ip_start, pint_t ip_end, pint_t fde);
128	static void removeAllIn(pint_t mh);
129	static void iterateCacheEntries(void (*func)(unw_word_t ip_start,
130	unw_word_t ip_end,
131	unw_word_t fde, unw_word_t mh));
132
133	private:
134
135	struct entry {
136	pint_t mh;
137	pint_t ip_start;
138	pint_t ip_end;
139	pint_t fde;
140	};
141
142	// These fields are all static to avoid needing an initializer.
143	// There is only one instance of this class per process.
144	static RWMutex _lock;
145	#ifdef __APPLE__
146	static void dyldUnloadHook(const struct mach_header *mh, intptr_t slide);
147	static bool _registeredForDyldUnloads;
148	#endif
149	static entry *_buffer;
150	static entry *_bufferUsed;
151	static entry *_bufferEnd;
152	static entry _initialBuffer[`64`];
153	};
154
155	template <typename A>
156	typename DwarfFDECache<A>::entry *
157	DwarfFDECache<A>::_buffer = _initialBuffer;
158
159	template <typename A>
160	typename DwarfFDECache<A>::entry *
161	DwarfFDECache<A>::_bufferUsed = _initialBuffer;
162
163	template <typename A>
164	typename DwarfFDECache<A>::entry *
165	DwarfFDECache<A>::_bufferEnd = &_initialBuffer[`64`];
166
167	template <typename A>
168	typename DwarfFDECache<A>::entry DwarfFDECache<A>::_initialBuffer[`64`];
169
170	template <typename A>
171	RWMutex DwarfFDECache<A>::_lock;
172
173	#ifdef __APPLE__
174	template <typename A>
175	bool DwarfFDECache<A>::_registeredForDyldUnloads = false;
176	#endif
177
178	template <typename A>
179	template <typename R>
180	typename DwarfFDECache<A>::pint_t
181	DwarfFDECache<A>::findFDE(pint_t mh, typename R::link_hardened_reg_arg_t pc) {
182	pint_t result = `0`;
183	_LIBUNWIND_LOG_IF_FALSE(_lock.lock_shared());
184	for (entry *p = _buffer; p < _bufferUsed; ++p) {
185	if ((mh == p->mh) \|\| (mh == kSearchAll)) {
186	if ((p->ip_start <= pc) && (pc < p->ip_end)) {
187	result = p->fde;
188	break;
189	}
190	}
191	}
192	_LIBUNWIND_LOG_IF_FALSE(_lock.unlock_shared());
193	return result;
194	}
195
196	template <typename A>
197	void DwarfFDECache<A>::add(pint_t mh, pint_t ip_start, pint_t ip_end,
198	pint_t fde) {
199	#if !defined(_LIBUNWIND_NO_HEAP)
200	_LIBUNWIND_LOG_IF_FALSE(_lock.lock());
201	if (_bufferUsed >= _bufferEnd) {
202	size_t oldSize = (size_t)(_bufferEnd - _buffer);
203	size_t newSize = oldSize * `4`;
204	// Can't use operator new (we are below it).
205	entry newBuffer = (entry )malloc(size: newSize * sizeof(entry));
206	memcpy(newBuffer, _buffer, oldSize * sizeof(entry));
207	if (_buffer != _initialBuffer)
208	free(_buffer);
209	_buffer = newBuffer;
210	_bufferUsed = &newBuffer[oldSize];
211	_bufferEnd = &newBuffer[newSize];
212	}
213	_bufferUsed->mh = mh;
214	_bufferUsed->ip_start = ip_start;
215	_bufferUsed->ip_end = ip_end;
216	_bufferUsed->fde = fde;
217	++_bufferUsed;
218	#ifdef __APPLE__
219	if (!_registeredForDyldUnloads) {
220	_dyld_register_func_for_remove_image(&dyldUnloadHook);
221	_registeredForDyldUnloads = true;
222	}
223	#endif
224	_LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
225	#endif
226	}
227
228	template <typename A>
229	void DwarfFDECache<A>::removeAllIn(pint_t mh) {
230	_LIBUNWIND_LOG_IF_FALSE(_lock.lock());
231	entry *d = _buffer;
232	for (const entry *s = _buffer; s < _bufferUsed; ++s) {
233	if (s->mh != mh) {
234	if (d != s)
235	d = s;
236	++d;
237	}
238	}
239	_bufferUsed = d;
240	_LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
241	}
242
243	#ifdef __APPLE__
244	template <typename A>
245	void DwarfFDECache<A>::dyldUnloadHook(const struct mach_header *mh, intptr_t ) {
246	removeAllIn((pint_t) mh);
247	}
248	#endif
249
250	template <typename A>
251	void DwarfFDECache<A>::iterateCacheEntries(void (*func)(
252	unw_word_t ip_start, unw_word_t ip_end, unw_word_t fde, unw_word_t mh)) {
253	_LIBUNWIND_LOG_IF_FALSE(_lock.lock());
254	for (entry *p = _buffer; p < _bufferUsed; ++p) {
255	(*func)(p->ip_start, p->ip_end, p->fde, p->mh);
256	}
257	_LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
258	}
259	#endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
260
261	#define arrayoffsetof(type, index, field) \
262	(sizeof(type) * (index) + offsetof(type, field))
263
264	#if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
265	template <typename A> class UnwindSectionHeader {
266	public:
267	UnwindSectionHeader(A &addressSpace, typename A::pint_t addr)
268	: _addressSpace(addressSpace), _addr(addr) {}
269
270	uint32_t version() const {
271	return _addressSpace.get32(_addr +
272	offsetof(unwind_info_section_header, version));
273	}
274	uint32_t commonEncodingsArraySectionOffset() const {
275	return _addressSpace.get32(_addr +
276	offsetof(unwind_info_section_header,
277	commonEncodingsArraySectionOffset));
278	}
279	uint32_t commonEncodingsArrayCount() const {
280	return _addressSpace.get32(_addr + offsetof(unwind_info_section_header,
281	commonEncodingsArrayCount));
282	}
283	uint32_t personalityArraySectionOffset() const {
284	return _addressSpace.get32(_addr + offsetof(unwind_info_section_header,
285	personalityArraySectionOffset));
286	}
287	uint32_t personalityArrayCount() const {
288	return _addressSpace.get32(
289	_addr + offsetof(unwind_info_section_header, personalityArrayCount));
290	}
291	uint32_t indexSectionOffset() const {
292	return _addressSpace.get32(
293	_addr + offsetof(unwind_info_section_header, indexSectionOffset));
294	}
295	uint32_t indexCount() const {
296	return _addressSpace.get32(
297	_addr + offsetof(unwind_info_section_header, indexCount));
298	}
299
300	private:
301	A &_addressSpace;
302	typename A::pint_t _addr;
303	};
304
305	template <typename A> class UnwindSectionIndexArray {
306	public:
307	UnwindSectionIndexArray(A &addressSpace, typename A::pint_t addr)
308	: _addressSpace(addressSpace), _addr(addr) {}
309
310	uint32_t functionOffset(uint32_t index) const {
311	return _addressSpace.get32(
312	_addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
313	functionOffset));
314	}
315	uint32_t secondLevelPagesSectionOffset(uint32_t index) const {
316	return _addressSpace.get32(
317	_addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
318	secondLevelPagesSectionOffset));
319	}
320	uint32_t lsdaIndexArraySectionOffset(uint32_t index) const {
321	return _addressSpace.get32(
322	_addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
323	lsdaIndexArraySectionOffset));
324	}
325
326	private:
327	A &_addressSpace;
328	typename A::pint_t _addr;
329	};
330
331	template <typename A> class UnwindSectionRegularPageHeader {
332	public:
333	UnwindSectionRegularPageHeader(A &addressSpace, typename A::pint_t addr)
334	: _addressSpace(addressSpace), _addr(addr) {}
335
336	uint32_t kind() const {
337	return _addressSpace.get32(
338	_addr + offsetof(unwind_info_regular_second_level_page_header, kind));
339	}
340	uint16_t entryPageOffset() const {
341	return _addressSpace.get16(
342	_addr + offsetof(unwind_info_regular_second_level_page_header,
343	entryPageOffset));
344	}
345	uint16_t entryCount() const {
346	return _addressSpace.get16(
347	_addr +
348	offsetof(unwind_info_regular_second_level_page_header, entryCount));
349	}
350
351	private:
352	A &_addressSpace;
353	typename A::pint_t _addr;
354	};
355
356	template <typename A> class UnwindSectionRegularArray {
357	public:
358	UnwindSectionRegularArray(A &addressSpace, typename A::pint_t addr)
359	: _addressSpace(addressSpace), _addr(addr) {}
360
361	uint32_t functionOffset(uint32_t index) const {
362	return _addressSpace.get32(
363	_addr + arrayoffsetof(unwind_info_regular_second_level_entry, index,
364	functionOffset));
365	}
366	uint32_t encoding(uint32_t index) const {
367	return _addressSpace.get32(
368	_addr +
369	arrayoffsetof(unwind_info_regular_second_level_entry, index, encoding));
370	}
371
372	private:
373	A &_addressSpace;
374	typename A::pint_t _addr;
375	};
376
377	template <typename A> class UnwindSectionCompressedPageHeader {
378	public:
379	UnwindSectionCompressedPageHeader(A &addressSpace, typename A::pint_t addr)
380	: _addressSpace(addressSpace), _addr(addr) {}
381
382	uint32_t kind() const {
383	return _addressSpace.get32(
384	_addr +
385	offsetof(unwind_info_compressed_second_level_page_header, kind));
386	}
387	uint16_t entryPageOffset() const {
388	return _addressSpace.get16(
389	_addr + offsetof(unwind_info_compressed_second_level_page_header,
390	entryPageOffset));
391	}
392	uint16_t entryCount() const {
393	return _addressSpace.get16(
394	_addr +
395	offsetof(unwind_info_compressed_second_level_page_header, entryCount));
396	}
397	uint16_t encodingsPageOffset() const {
398	return _addressSpace.get16(
399	_addr + offsetof(unwind_info_compressed_second_level_page_header,
400	encodingsPageOffset));
401	}
402	uint16_t encodingsCount() const {
403	return _addressSpace.get16(
404	_addr + offsetof(unwind_info_compressed_second_level_page_header,
405	encodingsCount));
406	}
407
408	private:
409	A &_addressSpace;
410	typename A::pint_t _addr;
411	};
412
413	template <typename A> class UnwindSectionCompressedArray {
414	public:
415	UnwindSectionCompressedArray(A &addressSpace, typename A::pint_t addr)
416	: _addressSpace(addressSpace), _addr(addr) {}
417
418	uint32_t functionOffset(uint32_t index) const {
419	return UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET(
420	_addressSpace.get32(_addr + index * sizeof(uint32_t)));
421	}
422	uint16_t encodingIndex(uint32_t index) const {
423	return UNWIND_INFO_COMPRESSED_ENTRY_ENCODING_INDEX(
424	_addressSpace.get32(_addr + index * sizeof(uint32_t)));
425	}
426
427	private:
428	A &_addressSpace;
429	typename A::pint_t _addr;
430	};
431
432	template <typename A> class UnwindSectionLsdaArray {
433	public:
434	UnwindSectionLsdaArray(A &addressSpace, typename A::pint_t addr)
435	: _addressSpace(addressSpace), _addr(addr) {}
436
437	uint32_t functionOffset(uint32_t index) const {
438	return _addressSpace.get32(
439	_addr + arrayoffsetof(unwind_info_section_header_lsda_index_entry,
440	index, functionOffset));
441	}
442	uint32_t lsdaOffset(uint32_t index) const {
443	return _addressSpace.get32(
444	_addr + arrayoffsetof(unwind_info_section_header_lsda_index_entry,
445	index, lsdaOffset));
446	}
447
448	private:
449	A &_addressSpace;
450	typename A::pint_t _addr;
451	};
452	#endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
453
454	class _LIBUNWIND_HIDDEN AbstractUnwindCursor {
455	public:
456	// NOTE: provide a class specific placement deallocation function (S5.3.4 p20)
457	// This avoids an unnecessary dependency to libc++abi.
458	void operator delete(void *, size_t) {}
459
460	virtual ~AbstractUnwindCursor() {}
461	virtual bool validReg(int) { _LIBUNWIND_ABORT("validReg not implemented"); }
462	virtual unw_word_t getReg(int) { _LIBUNWIND_ABORT("getReg not implemented"); }
463	virtual void setReg(int, unw_word_t) {
464	_LIBUNWIND_ABORT("setReg not implemented");
465	}
466	virtual bool validFloatReg(int) {
467	_LIBUNWIND_ABORT("validFloatReg not implemented");
468	}
469	virtual unw_fpreg_t getFloatReg(int) {
470	_LIBUNWIND_ABORT("getFloatReg not implemented");
471	}
472	virtual void setFloatReg(int, unw_fpreg_t) {
473	_LIBUNWIND_ABORT("setFloatReg not implemented");
474	}
475	virtual int step(bool = false) { _LIBUNWIND_ABORT("step not implemented"); }
476	virtual void getInfo(unw_proc_info_t *) {
477	_LIBUNWIND_ABORT("getInfo not implemented");
478	}
479	_LIBUNWIND_TRACE_NO_INLINE virtual void jumpto() {
480	_LIBUNWIND_ABORT("jumpto not implemented");
481	}
482	virtual bool isSignalFrame() {
483	_LIBUNWIND_ABORT("isSignalFrame not implemented");
484	}
485	virtual bool getFunctionName(char , size_t, unw_word_t ) {
486	_LIBUNWIND_ABORT("getFunctionName not implemented");
487	}
488	virtual void setInfoBasedOnIPRegister(bool = false) {
489	_LIBUNWIND_ABORT("setInfoBasedOnIPRegister not implemented");
490	}
491	virtual const char getRegisterName(int*) {
492	_LIBUNWIND_ABORT("getRegisterName not implemented");
493	}
494	#ifdef __arm__
495	virtual void saveVFPAsX() { _LIBUNWIND_ABORT("saveVFPAsX not implemented"); }
496	#endif
497
498	#ifdef _LIBUNWIND_TRACE_RET_INJECT
499	virtual void setWalkedFrames(unsigned) {
500	_LIBUNWIND_ABORT("setWalkedFrames not implemented");
501	}
502	#endif
503
504	#ifdef _AIX
505	virtual uintptr_t getDataRelBase() {
506	_LIBUNWIND_ABORT("getDataRelBase not implemented");
507	}
508	#endif
509
510	#if defined(_LIBUNWIND_USE_CET) \|\| defined(_LIBUNWIND_USE_GCS)
511	virtual void *get_registers() {
512	_LIBUNWIND_ABORT("get_registers not implemented");
513	}
514	#endif
515	};
516
517	#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) && defined(_WIN32)
518
519	/// \c UnwindCursor contains all state (including all register values) during
520	/// an unwind. This is normally stack-allocated inside a unw_cursor_t.
521	template <typename A, typename R>
522	class UnwindCursor : public AbstractUnwindCursor {
523	typedef typename A::pint_t pint_t;
524	public:
525	UnwindCursor(unw_context_t *context, A &as);
526	UnwindCursor(CONTEXT *context, A &as);
527	UnwindCursor(A &as, void *threadArg);
528	virtual ~UnwindCursor() {}
529	virtual bool validReg(int);
530	virtual unw_word_t getReg(int);
531	virtual void setReg(int, unw_word_t);
532	virtual bool validFloatReg(int);
533	virtual unw_fpreg_t getFloatReg(int);
534	virtual void setFloatReg(int, unw_fpreg_t);
535	virtual int step(bool = false);
536	virtual void getInfo(unw_proc_info_t *);
537	virtual void jumpto();
538	virtual bool isSignalFrame();
539	virtual bool getFunctionName(char buf, size_t len, unw_word_t off);
540	virtual void setInfoBasedOnIPRegister(bool isReturnAddress = false);
541	virtual const char getRegisterName(int* num);
542	#ifdef __arm__
543	virtual void saveVFPAsX();
544	#endif
545
546	DISPATCHER_CONTEXT getDispatcherContext() { return* &_dispContext; }
547	void setDispatcherContext(DISPATCHER_CONTEXT *disp) {
548	_dispContext = *disp;
549	_info.lsda = reinterpret_cast<unw_word_t>(_dispContext.HandlerData);
550	if (_dispContext.LanguageHandler) {
551	_info.handler = reinterpret_cast<unw_word_t>(__libunwind_seh_personality);
552	} else
553	_info.handler = `0`;
554	}
555
556	// libunwind does not and should not depend on C++ library which means that we
557	// need our own definition of inline placement new.
558	static void *operator new(size_t, UnwindCursor<A, R> p) { return* p; }
559
560	private:
561
562	pint_t getLastPC() const { return _dispContext.ControlPc; }
563	void setLastPC(pint_t pc) { _dispContext.ControlPc = pc; }
564	RUNTIME_FUNCTION lookUpSEHUnwindInfo(pint_t pc, pint_t base) {
565	#ifdef __arm__
566	// Remove the thumb bit; FunctionEntry ranges don't include the thumb bit.
567	pc &= ~`1U`;
568	#endif
569	// If pc points exactly at the end of the range, we might resolve the
570	// next function instead. Decrement pc by 1 to fit inside the current
571	// function.
572	pc -= `1`;
573	_dispContext.FunctionEntry = RtlLookupFunctionEntry(pc,
574	&_dispContext.ImageBase,
575	_dispContext.HistoryTable);
576	*base = _dispContext.ImageBase;
577	return _dispContext.FunctionEntry;
578	}
579	bool getInfoFromSEH(pint_t pc);
580	int stepWithSEHData() {
581	_dispContext.LanguageHandler = RtlVirtualUnwind(UNW_FLAG_UHANDLER,
582	_dispContext.ImageBase,
583	_dispContext.ControlPc,
584	_dispContext.FunctionEntry,
585	_dispContext.ContextRecord,
586	&_dispContext.HandlerData,
587	&_dispContext.EstablisherFrame,
588	NULL);
589	// Update some fields of the unwind info now, since we have them.
590	_info.lsda = reinterpret_cast<unw_word_t>(_dispContext.HandlerData);
591	if (_dispContext.LanguageHandler) {
592	_info.handler = reinterpret_cast<unw_word_t>(__libunwind_seh_personality);
593	} else
594	_info.handler = `0`;
595	return UNW_STEP_SUCCESS;
596	}
597
598	A &_addressSpace;
599	unw_proc_info_t _info;
600	DISPATCHER_CONTEXT _dispContext;
601	CONTEXT _msContext;
602	UNWIND_HISTORY_TABLE _histTable;
603	bool _unwindInfoMissing;
604	};
605
606
607	template <typename A, typename R>
608	UnwindCursor<A, R>::UnwindCursor(unw_context_t *context, A &as)
609	: _addressSpace(as), _unwindInfoMissing(false) {
610	static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
611	"UnwindCursor<> does not fit in unw_cursor_t");
612	static_assert((alignof(UnwindCursor<A, R>) <= alignof(unw_cursor_t)),
613	"UnwindCursor<> requires more alignment than unw_cursor_t");
614	memset(&_info, `0`, sizeof(_info));
615	memset(&_histTable, `0`, sizeof(_histTable));
616	memset(&_dispContext, `0`, sizeof(_dispContext));
617	_dispContext.ContextRecord = &_msContext;
618	_dispContext.HistoryTable = &_histTable;
619	// Initialize MS context from ours.
620	R r(context);
621	RtlCaptureContext(&_msContext);
622	_msContext.ContextFlags = CONTEXT_CONTROL\|CONTEXT_INTEGER\|CONTEXT_FLOATING_POINT;
623	#if defined(_LIBUNWIND_TARGET_X86_64)
624	_msContext.Rax = r.getRegister(UNW_X86_64_RAX);
625	_msContext.Rcx = r.getRegister(UNW_X86_64_RCX);
626	_msContext.Rdx = r.getRegister(UNW_X86_64_RDX);
627	_msContext.Rbx = r.getRegister(UNW_X86_64_RBX);
628	_msContext.Rsp = r.getRegister(UNW_X86_64_RSP);
629	_msContext.Rbp = r.getRegister(UNW_X86_64_RBP);
630	_msContext.Rsi = r.getRegister(UNW_X86_64_RSI);
631	_msContext.Rdi = r.getRegister(UNW_X86_64_RDI);
632	_msContext.R8 = r.getRegister(UNW_X86_64_R8);
633	_msContext.R9 = r.getRegister(UNW_X86_64_R9);
634	_msContext.R10 = r.getRegister(UNW_X86_64_R10);
635	_msContext.R11 = r.getRegister(UNW_X86_64_R11);
636	_msContext.R12 = r.getRegister(UNW_X86_64_R12);
637	_msContext.R13 = r.getRegister(UNW_X86_64_R13);
638	_msContext.R14 = r.getRegister(UNW_X86_64_R14);
639	_msContext.R15 = r.getRegister(UNW_X86_64_R15);
640	_msContext.Rip = r.getRegister(UNW_REG_IP);
641	union {
642	v128 v;
643	M128A m;
644	} t;
645	t.v = r.getVectorRegister(UNW_X86_64_XMM0);
646	_msContext.Xmm0 = t.m;
647	t.v = r.getVectorRegister(UNW_X86_64_XMM1);
648	_msContext.Xmm1 = t.m;
649	t.v = r.getVectorRegister(UNW_X86_64_XMM2);
650	_msContext.Xmm2 = t.m;
651	t.v = r.getVectorRegister(UNW_X86_64_XMM3);
652	_msContext.Xmm3 = t.m;
653	t.v = r.getVectorRegister(UNW_X86_64_XMM4);
654	_msContext.Xmm4 = t.m;
655	t.v = r.getVectorRegister(UNW_X86_64_XMM5);
656	_msContext.Xmm5 = t.m;
657	t.v = r.getVectorRegister(UNW_X86_64_XMM6);
658	_msContext.Xmm6 = t.m;
659	t.v = r.getVectorRegister(UNW_X86_64_XMM7);
660	_msContext.Xmm7 = t.m;
661	t.v = r.getVectorRegister(UNW_X86_64_XMM8);
662	_msContext.Xmm8 = t.m;
663	t.v = r.getVectorRegister(UNW_X86_64_XMM9);
664	_msContext.Xmm9 = t.m;
665	t.v = r.getVectorRegister(UNW_X86_64_XMM10);
666	_msContext.Xmm10 = t.m;
667	t.v = r.getVectorRegister(UNW_X86_64_XMM11);
668	_msContext.Xmm11 = t.m;
669	t.v = r.getVectorRegister(UNW_X86_64_XMM12);
670	_msContext.Xmm12 = t.m;
671	t.v = r.getVectorRegister(UNW_X86_64_XMM13);
672	_msContext.Xmm13 = t.m;
673	t.v = r.getVectorRegister(UNW_X86_64_XMM14);
674	_msContext.Xmm14 = t.m;
675	t.v = r.getVectorRegister(UNW_X86_64_XMM15);
676	_msContext.Xmm15 = t.m;
677	#elif defined(_LIBUNWIND_TARGET_ARM)
678	_msContext.R0 = r.getRegister(UNW_ARM_R0);
679	_msContext.R1 = r.getRegister(UNW_ARM_R1);
680	_msContext.R2 = r.getRegister(UNW_ARM_R2);
681	_msContext.R3 = r.getRegister(UNW_ARM_R3);
682	_msContext.R4 = r.getRegister(UNW_ARM_R4);
683	_msContext.R5 = r.getRegister(UNW_ARM_R5);
684	_msContext.R6 = r.getRegister(UNW_ARM_R6);
685	_msContext.R7 = r.getRegister(UNW_ARM_R7);
686	_msContext.R8 = r.getRegister(UNW_ARM_R8);
687	_msContext.R9 = r.getRegister(UNW_ARM_R9);
688	_msContext.R10 = r.getRegister(UNW_ARM_R10);
689	_msContext.R11 = r.getRegister(UNW_ARM_R11);
690	_msContext.R12 = r.getRegister(UNW_ARM_R12);
691	_msContext.Sp = r.getRegister(UNW_ARM_SP);
692	_msContext.Lr = r.getRegister(UNW_ARM_LR);
693	_msContext.Pc = r.getRegister(UNW_ARM_IP);
694	for (int i = UNW_ARM_D0; i <= UNW_ARM_D31; ++i) {
695	union {
696	uint64_t w;
697	double d;
698	} d;
699	d.d = r.getFloatRegister(i);
700	_msContext.D[i - UNW_ARM_D0] = d.w;
701	}
702	#elif defined(_LIBUNWIND_TARGET_AARCH64)
703	for (int i = UNW_AARCH64_X0; i <= UNW_ARM64_X30; ++i)
704	_msContext.X[i - UNW_AARCH64_X0] = r.getRegister(i);
705	_msContext.Sp = r.getRegister(UNW_REG_SP);
706	_msContext.Pc = r.getRegister(UNW_REG_IP);
707	for (int i = UNW_AARCH64_V0; i <= UNW_ARM64_D31; ++i)
708	_msContext.V[i - UNW_AARCH64_V0].D[`0`] = r.getFloatRegister(i);
709	#endif
710	}
711
712	template <typename A, typename R>
713	UnwindCursor<A, R>::UnwindCursor(CONTEXT *context, A &as)
714	: _addressSpace(as), _unwindInfoMissing(false) {
715	static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
716	"UnwindCursor<> does not fit in unw_cursor_t");
717	memset(&_info, `0`, sizeof(_info));
718	memset(&_histTable, `0`, sizeof(_histTable));
719	memset(&_dispContext, `0`, sizeof(_dispContext));
720	_dispContext.ContextRecord = &_msContext;
721	_dispContext.HistoryTable = &_histTable;
722	_msContext = *context;
723	}
724
725
726	template <typename A, typename R>
727	bool UnwindCursor<A, R>::validReg(int regNum) {
728	if (regNum == UNW_REG_IP \|\| regNum == UNW_REG_SP) return true;
729	#if defined(_LIBUNWIND_TARGET_X86_64)
730	if (regNum >= UNW_X86_64_RAX && regNum <= UNW_X86_64_RIP) return true;
731	#elif defined(_LIBUNWIND_TARGET_ARM)
732	if ((regNum >= UNW_ARM_R0 && regNum <= UNW_ARM_R15) \|\|
733	regNum == UNW_ARM_RA_AUTH_CODE)
734	return true;
735	#elif defined(_LIBUNWIND_TARGET_AARCH64)
736	if (regNum >= UNW_AARCH64_X0 && regNum <= UNW_ARM64_X30) return true;
737	#endif
738	return false;
739	}
740
741	template <typename A, typename R>
742	unw_word_t UnwindCursor<A, R>::getReg(int regNum) {
743	switch (regNum) {
744	#if defined(_LIBUNWIND_TARGET_X86_64)
745	case UNW_X86_64_RIP:
746	case UNW_REG_IP: return _msContext.Rip;
747	case UNW_X86_64_RAX: return _msContext.Rax;
748	case UNW_X86_64_RDX: return _msContext.Rdx;
749	case UNW_X86_64_RCX: return _msContext.Rcx;
750	case UNW_X86_64_RBX: return _msContext.Rbx;
751	case UNW_REG_SP:
752	case UNW_X86_64_RSP: return _msContext.Rsp;
753	case UNW_X86_64_RBP: return _msContext.Rbp;
754	case UNW_X86_64_RSI: return _msContext.Rsi;
755	case UNW_X86_64_RDI: return _msContext.Rdi;
756	case UNW_X86_64_R8: return _msContext.R8;
757	case UNW_X86_64_R9: return _msContext.R9;
758	case UNW_X86_64_R10: return _msContext.R10;
759	case UNW_X86_64_R11: return _msContext.R11;
760	case UNW_X86_64_R12: return _msContext.R12;
761	case UNW_X86_64_R13: return _msContext.R13;
762	case UNW_X86_64_R14: return _msContext.R14;
763	case UNW_X86_64_R15: return _msContext.R15;
764	#elif defined(_LIBUNWIND_TARGET_ARM)
765	case UNW_ARM_R0: return _msContext.R0;
766	case UNW_ARM_R1: return _msContext.R1;
767	case UNW_ARM_R2: return _msContext.R2;
768	case UNW_ARM_R3: return _msContext.R3;
769	case UNW_ARM_R4: return _msContext.R4;
770	case UNW_ARM_R5: return _msContext.R5;
771	case UNW_ARM_R6: return _msContext.R6;
772	case UNW_ARM_R7: return _msContext.R7;
773	case UNW_ARM_R8: return _msContext.R8;
774	case UNW_ARM_R9: return _msContext.R9;
775	case UNW_ARM_R10: return _msContext.R10;
776	case UNW_ARM_R11: return _msContext.R11;
777	case UNW_ARM_R12: return _msContext.R12;
778	case UNW_REG_SP:
779	case UNW_ARM_SP: return _msContext.Sp;
780	case UNW_ARM_LR: return _msContext.Lr;
781	case UNW_REG_IP:
782	case UNW_ARM_IP: return _msContext.Pc;
783	#elif defined(_LIBUNWIND_TARGET_AARCH64)
784	case UNW_REG_SP: return _msContext.Sp;
785	case UNW_REG_IP: return _msContext.Pc;
786	default: return _msContext.X[regNum - UNW_AARCH64_X0];
787	#endif
788	}
789	_LIBUNWIND_ABORT("unsupported register");
790	}
791
792	template <typename A, typename R>
793	void UnwindCursor<A, R>::setReg(int regNum, unw_word_t value) {
794	switch (regNum) {
795	#if defined(_LIBUNWIND_TARGET_X86_64)
796	case UNW_X86_64_RIP:
797	case UNW_REG_IP: _msContext.Rip = value; break;
798	case UNW_X86_64_RAX: _msContext.Rax = value; break;
799	case UNW_X86_64_RDX: _msContext.Rdx = value; break;
800	case UNW_X86_64_RCX: _msContext.Rcx = value; break;
801	case UNW_X86_64_RBX: _msContext.Rbx = value; break;
802	case UNW_REG_SP:
803	case UNW_X86_64_RSP: _msContext.Rsp = value; break;
804	case UNW_X86_64_RBP: _msContext.Rbp = value; break;
805	case UNW_X86_64_RSI: _msContext.Rsi = value; break;
806	case UNW_X86_64_RDI: _msContext.Rdi = value; break;
807	case UNW_X86_64_R8: _msContext.R8 = value; break;
808	case UNW_X86_64_R9: _msContext.R9 = value; break;
809	case UNW_X86_64_R10: _msContext.R10 = value; break;
810	case UNW_X86_64_R11: _msContext.R11 = value; break;
811	case UNW_X86_64_R12: _msContext.R12 = value; break;
812	case UNW_X86_64_R13: _msContext.R13 = value; break;
813	case UNW_X86_64_R14: _msContext.R14 = value; break;
814	case UNW_X86_64_R15: _msContext.R15 = value; break;
815	#elif defined(_LIBUNWIND_TARGET_ARM)
816	case UNW_ARM_R0: _msContext.R0 = value; break;
817	case UNW_ARM_R1: _msContext.R1 = value; break;
818	case UNW_ARM_R2: _msContext.R2 = value; break;
819	case UNW_ARM_R3: _msContext.R3 = value; break;
820	case UNW_ARM_R4: _msContext.R4 = value; break;
821	case UNW_ARM_R5: _msContext.R5 = value; break;
822	case UNW_ARM_R6: _msContext.R6 = value; break;
823	case UNW_ARM_R7: _msContext.R7 = value; break;
824	case UNW_ARM_R8: _msContext.R8 = value; break;
825	case UNW_ARM_R9: _msContext.R9 = value; break;
826	case UNW_ARM_R10: _msContext.R10 = value; break;
827	case UNW_ARM_R11: _msContext.R11 = value; break;
828	case UNW_ARM_R12: _msContext.R12 = value; break;
829	case UNW_REG_SP:
830	case UNW_ARM_SP: _msContext.Sp = value; break;
831	case UNW_ARM_LR: _msContext.Lr = value; break;
832	case UNW_REG_IP:
833	case UNW_ARM_IP: _msContext.Pc = value; break;
834	#elif defined(_LIBUNWIND_TARGET_AARCH64)
835	case UNW_REG_SP: _msContext.Sp = value; break;
836	case UNW_REG_IP: _msContext.Pc = value; break;
837	case UNW_AARCH64_X0:
838	case UNW_AARCH64_X1:
839	case UNW_AARCH64_X2:
840	case UNW_AARCH64_X3:
841	case UNW_AARCH64_X4:
842	case UNW_AARCH64_X5:
843	case UNW_AARCH64_X6:
844	case UNW_AARCH64_X7:
845	case UNW_AARCH64_X8:
846	case UNW_AARCH64_X9:
847	case UNW_AARCH64_X10:
848	case UNW_AARCH64_X11:
849	case UNW_AARCH64_X12:
850	case UNW_AARCH64_X13:
851	case UNW_AARCH64_X14:
852	case UNW_AARCH64_X15:
853	case UNW_AARCH64_X16:
854	case UNW_AARCH64_X17:
855	case UNW_AARCH64_X18:
856	case UNW_AARCH64_X19:
857	case UNW_AARCH64_X20:
858	case UNW_AARCH64_X21:
859	case UNW_AARCH64_X22:
860	case UNW_AARCH64_X23:
861	case UNW_AARCH64_X24:
862	case UNW_AARCH64_X25:
863	case UNW_AARCH64_X26:
864	case UNW_AARCH64_X27:
865	case UNW_AARCH64_X28:
866	case UNW_AARCH64_FP:
867	case UNW_AARCH64_LR: _msContext.X[regNum - UNW_ARM64_X0] = value; break;
868	#endif
869	default:
870	_LIBUNWIND_ABORT("unsupported register");
871	}
872	}
873
874	template <typename A, typename R>
875	bool UnwindCursor<A, R>::validFloatReg(int regNum) {
876	#if defined(_LIBUNWIND_TARGET_ARM)
877	if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) return true;
878	if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) return true;
879	#elif defined(_LIBUNWIND_TARGET_AARCH64)
880	if (regNum >= UNW_AARCH64_V0 && regNum <= UNW_ARM64_D31) return true;
881	#else
882	(void)regNum;
883	#endif
884	return false;
885	}
886
887	template <typename A, typename R>
888	unw_fpreg_t UnwindCursor<A, R>::getFloatReg(int regNum) {
889	#if defined(_LIBUNWIND_TARGET_ARM)
890	if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) {
891	union {
892	uint32_t w;
893	float f;
894	} d;
895	d.w = _msContext.S[regNum - UNW_ARM_S0];
896	return d.f;
897	}
898	if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) {
899	union {
900	uint64_t w;
901	double d;
902	} d;
903	d.w = _msContext.D[regNum - UNW_ARM_D0];
904	return d.d;
905	}
906	_LIBUNWIND_ABORT("unsupported float register");
907	#elif defined(_LIBUNWIND_TARGET_AARCH64)
908	return _msContext.V[regNum - UNW_AARCH64_V0].D[`0`];
909	#else
910	(void)regNum;
911	_LIBUNWIND_ABORT("float registers unimplemented");
912	#endif
913	}
914
915	template <typename A, typename R>
916	void UnwindCursor<A, R>::setFloatReg(int regNum, unw_fpreg_t value) {
917	#if defined(_LIBUNWIND_TARGET_ARM)
918	if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) {
919	union {
920	uint32_t w;
921	float f;
922	} d;
923	d.f = (float)value;
924	_msContext.S[regNum - UNW_ARM_S0] = d.w;
925	}
926	if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) {
927	union {
928	uint64_t w;
929	double d;
930	} d;
931	d.d = value;
932	_msContext.D[regNum - UNW_ARM_D0] = d.w;
933	}
934	_LIBUNWIND_ABORT("unsupported float register");
935	#elif defined(_LIBUNWIND_TARGET_AARCH64)
936	_msContext.V[regNum - UNW_AARCH64_V0].D[`0`] = value;
937	#else
938	(void)regNum;
939	(void)value;
940	_LIBUNWIND_ABORT("float registers unimplemented");
941	#endif
942	}
943
944	template <typename A, typename R> void UnwindCursor<A, R>::jumpto() {
945	RtlRestoreContext(&_msContext, nullptr);
946	}
947
948	#ifdef __arm__
949	template <typename A, typename R> void UnwindCursor<A, R>::saveVFPAsX() {}
950	#endif
951
952	template <typename A, typename R>
953	const char UnwindCursor<A, R>::getRegisterName(int* regNum) {
954	return R::getRegisterName(regNum);
955	}
956
957	template <typename A, typename R> bool UnwindCursor<A, R>::isSignalFrame() {
958	return false;
959	}
960
961	#else // !defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) \|\| !defined(_WIN32)
962
963	/// UnwindCursor contains all state (including all register values) during
964	/// an unwind. This is normally stack allocated inside a unw_cursor_t.
965	template <typename A, typename R>
966	class UnwindCursor : public AbstractUnwindCursor {
967	typedef typename A::pint_t pint_t;
968	public:
969	UnwindCursor(unw_context_t *context, A &as);
970	UnwindCursor(A &as, void *threadArg);
971	virtual ~UnwindCursor() {}
972	virtual bool validReg(int);
973	virtual unw_word_t getReg(int);
974	virtual void setReg(int, unw_word_t);
975	virtual bool validFloatReg(int);
976	virtual unw_fpreg_t getFloatReg(int);
977	virtual void setFloatReg(int, unw_fpreg_t);
978	virtual int step(bool stage2 = false);
979	virtual void getInfo(unw_proc_info_t *);
980	_LIBUNWIND_TRACE_NO_INLINE
981	virtual void jumpto();
982	virtual bool isSignalFrame();
983	virtual bool getFunctionName(char buf, size_t len, unw_word_t off);
984	virtual void setInfoBasedOnIPRegister(bool isReturnAddress = false);
985	virtual const char getRegisterName(int* num);
986	#ifdef __arm__
987	virtual void saveVFPAsX();
988	#endif
989
990	#ifdef _LIBUNWIND_TRACE_RET_INJECT
991	virtual void setWalkedFrames(unsigned);
992	#endif
993
994	#ifdef _AIX
995	virtual uintptr_t getDataRelBase();
996	#endif
997
998	#if defined(_LIBUNWIND_USE_CET) \|\| defined(_LIBUNWIND_USE_GCS)
999	virtual void get_registers() { return* &_registers; }
1000	#endif
1001
1002	// libunwind does not and should not depend on C++ library which means that we
1003	// need our own definition of inline placement new.
1004	static void *operator new(size_t, UnwindCursor<A, R> p) { return* p; }
1005
1006	private:
1007
1008	#if defined(_LIBUNWIND_ARM_EHABI)
1009	bool getInfoFromEHABISection(pint_t pc, const UnwindInfoSections &sects);
1010
1011	int stepWithEHABI() {
1012	size_t len = `0`;
1013	size_t off = `0`;
1014	// FIXME: Calling decode_eht_entry() here is violating the libunwind
1015	// abstraction layer.
1016	const uint32_t *ehtp =
1017	decode_eht_entry(reinterpret_cast<const uint32_t *>(_info.unwind_info),
1018	&off, &len);
1019	if (_Unwind_VRS_Interpret((_Unwind_Context )this*, ehtp, off, len) !=
1020	_URC_CONTINUE_UNWIND)
1021	return UNW_STEP_END;
1022	return UNW_STEP_SUCCESS;
1023	}
1024	#endif
1025
1026	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN)
1027	bool setInfoForSigReturn() {
1028	R dummy;
1029	return setInfoForSigReturn(dummy);
1030	}
1031	int stepThroughSigReturn() {
1032	R dummy;
1033	return stepThroughSigReturn(dummy);
1034	}
1035	bool isReadableAddr(const pint_t addr) const;
1036	#if defined(_LIBUNWIND_TARGET_AARCH64)
1037	bool setInfoForSigReturn(Registers_arm64 &);
1038	int stepThroughSigReturn(Registers_arm64 &);
1039	#endif
1040	#if defined(_LIBUNWIND_TARGET_LOONGARCH)
1041	bool setInfoForSigReturn(Registers_loongarch &);
1042	int stepThroughSigReturn(Registers_loongarch &);
1043	#endif
1044	#if defined(_LIBUNWIND_TARGET_RISCV)
1045	bool setInfoForSigReturn(Registers_riscv &);
1046	int stepThroughSigReturn(Registers_riscv &);
1047	#endif
1048	#if defined(_LIBUNWIND_TARGET_S390X)
1049	bool setInfoForSigReturn(Registers_s390x &);
1050	int stepThroughSigReturn(Registers_s390x &);
1051	#endif
1052	template <typename Registers> bool setInfoForSigReturn(Registers &) {
1053	return false;
1054	}
1055	template <typename Registers> int stepThroughSigReturn(Registers &) {
1056	return UNW_STEP_END;
1057	}
1058	#elif defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
1059	bool setInfoForSigReturn();
1060	int stepThroughSigReturn();
1061	#endif
1062
1063	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1064	bool getInfoFromFdeCie(const typename CFI_Parser<A>::FDE_Info &fdeInfo,
1065	const typename CFI_Parser<A>::CIE_Info &cieInfo,
1066	typename R::link_hardened_reg_arg_t pc,
1067	uintptr_t dso_base);
1068	bool getInfoFromDwarfSection(typename R::link_hardened_reg_arg_t pc,
1069	const UnwindInfoSections &sects,
1070	uint32_t fdeSectionOffsetHint = `0`);
1071	int stepWithDwarfFDE(bool stage2) {
1072	#if defined(_LIBUNWIND_TARGET_AARCH64_AUTHENTICATED_UNWINDING)
1073	typename R::reg_t rawPC = this->getReg(UNW_REG_IP);
1074	typename R::link_reg_t pc;
1075	_registers.loadAndAuthenticateLinkRegister(rawPC, &pc);
1076	#else
1077	typename R::link_reg_t pc = this->getReg(UNW_REG_IP);
1078	#endif
1079	return DwarfInstructions<A, R>::stepWithDwarf(
1080	_addressSpace, pc, (pint_t)_info.unwind_info, _registers,
1081	_isSignalFrame, stage2);
1082	}
1083	#endif
1084
1085	#if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1086	bool getInfoFromCompactEncodingSection(typename R::link_hardened_reg_arg_t pc,
1087	const UnwindInfoSections &sects);
1088	int stepWithCompactEncoding(bool stage2 = false) {
1089	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1090	if ( compactSaysUseDwarf() )
1091	return stepWithDwarfFDE(stage2);
1092	#endif
1093	R dummy;
1094	return stepWithCompactEncoding(dummy);
1095	}
1096
1097	#if defined(_LIBUNWIND_TARGET_X86_64)
1098	int stepWithCompactEncoding(Registers_x86_64 &) {
1099	return CompactUnwinder_x86_64<A>::stepWithCompactEncoding(
1100	_info.format, _info.start_ip, _addressSpace, _registers);
1101	}
1102	#endif
1103
1104	#if defined(_LIBUNWIND_TARGET_I386)
1105	int stepWithCompactEncoding(Registers_x86 &) {
1106	return CompactUnwinder_x86<A>::stepWithCompactEncoding(
1107	_info.format, (uint32_t)_info.start_ip, _addressSpace, _registers);
1108	}
1109	#endif
1110
1111	#if defined(_LIBUNWIND_TARGET_PPC)
1112	int stepWithCompactEncoding(Registers_ppc &) {
1113	return UNW_EINVAL;
1114	}
1115	#endif
1116
1117	#if defined(_LIBUNWIND_TARGET_PPC64)
1118	int stepWithCompactEncoding(Registers_ppc64 &) {
1119	return UNW_EINVAL;
1120	}
1121	#endif
1122
1123
1124	#if defined(_LIBUNWIND_TARGET_AARCH64)
1125	int stepWithCompactEncoding(Registers_arm64 &) {
1126	return CompactUnwinder_arm64<A>::stepWithCompactEncoding(
1127	_info.format, _info.start_ip, _addressSpace, _registers);
1128	}
1129	#endif
1130
1131	#if defined(_LIBUNWIND_TARGET_MIPS_O32)
1132	int stepWithCompactEncoding(Registers_mips_o32 &) {
1133	return UNW_EINVAL;
1134	}
1135	#endif
1136
1137	#if defined(_LIBUNWIND_TARGET_MIPS_NEWABI)
1138	int stepWithCompactEncoding(Registers_mips_newabi &) {
1139	return UNW_EINVAL;
1140	}
1141	#endif
1142
1143	#if defined(_LIBUNWIND_TARGET_LOONGARCH)
1144	int stepWithCompactEncoding(Registers_loongarch &) { return UNW_EINVAL; }
1145	#endif
1146
1147	#if defined(_LIBUNWIND_TARGET_SPARC)
1148	int stepWithCompactEncoding(Registers_sparc &) { return UNW_EINVAL; }
1149	#endif
1150
1151	#if defined(_LIBUNWIND_TARGET_SPARC64)
1152	int stepWithCompactEncoding(Registers_sparc64 &) { return UNW_EINVAL; }
1153	#endif
1154
1155	#if defined (_LIBUNWIND_TARGET_RISCV)
1156	int stepWithCompactEncoding(Registers_riscv &) {
1157	return UNW_EINVAL;
1158	}
1159	#endif
1160
1161	bool compactSaysUseDwarf(uint32_t offset=NULL) const* {
1162	R dummy;
1163	return compactSaysUseDwarf(dummy, offset);
1164	}
1165
1166	#if defined(_LIBUNWIND_TARGET_X86_64)
1167	bool compactSaysUseDwarf(Registers_x86_64 &, uint32_t offset) const* {
1168	if ((_info.format & UNWIND_X86_64_MODE_MASK) == UNWIND_X86_64_MODE_DWARF) {
1169	if (offset)
1170	*offset = (_info.format & UNWIND_X86_64_DWARF_SECTION_OFFSET);
1171	return true;
1172	}
1173	return false;
1174	}
1175	#endif
1176
1177	#if defined(_LIBUNWIND_TARGET_I386)
1178	bool compactSaysUseDwarf(Registers_x86 &, uint32_t offset) const* {
1179	if ((_info.format & UNWIND_X86_MODE_MASK) == UNWIND_X86_MODE_DWARF) {
1180	if (offset)
1181	*offset = (_info.format & UNWIND_X86_DWARF_SECTION_OFFSET);
1182	return true;
1183	}
1184	return false;
1185	}
1186	#endif
1187
1188	#if defined(_LIBUNWIND_TARGET_PPC)
1189	bool compactSaysUseDwarf(Registers_ppc &, uint32_t ) const* {
1190	return true;
1191	}
1192	#endif
1193
1194	#if defined(_LIBUNWIND_TARGET_PPC64)
1195	bool compactSaysUseDwarf(Registers_ppc64 &, uint32_t ) const* {
1196	return true;
1197	}
1198	#endif
1199
1200	#if defined(_LIBUNWIND_TARGET_AARCH64)
1201	bool compactSaysUseDwarf(Registers_arm64 &, uint32_t offset) const* {
1202	if ((_info.format & UNWIND_ARM64_MODE_MASK) == UNWIND_ARM64_MODE_DWARF) {
1203	if (offset)
1204	*offset = (_info.format & UNWIND_ARM64_DWARF_SECTION_OFFSET);
1205	return true;
1206	}
1207	return false;
1208	}
1209	#endif
1210
1211	#if defined(_LIBUNWIND_TARGET_MIPS_O32)
1212	bool compactSaysUseDwarf(Registers_mips_o32 &, uint32_t ) const* {
1213	return true;
1214	}
1215	#endif
1216
1217	#if defined(_LIBUNWIND_TARGET_MIPS_NEWABI)
1218	bool compactSaysUseDwarf(Registers_mips_newabi &, uint32_t ) const* {
1219	return true;
1220	}
1221	#endif
1222
1223	#if defined(_LIBUNWIND_TARGET_LOONGARCH)
1224	bool compactSaysUseDwarf(Registers_loongarch &, uint32_t ) const* {
1225	return true;
1226	}
1227	#endif
1228
1229	#if defined(_LIBUNWIND_TARGET_SPARC)
1230	bool compactSaysUseDwarf(Registers_sparc &, uint32_t ) const* { return true; }
1231	#endif
1232
1233	#if defined(_LIBUNWIND_TARGET_SPARC64)
1234	bool compactSaysUseDwarf(Registers_sparc64 &, uint32_t ) const* {
1235	return true;
1236	}
1237	#endif
1238
1239	#if defined (_LIBUNWIND_TARGET_RISCV)
1240	bool compactSaysUseDwarf(Registers_riscv &, uint32_t ) const* {
1241	return true;
1242	}
1243	#endif
1244
1245	#endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1246
1247	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1248	compact_unwind_encoding_t dwarfEncoding() const {
1249	R dummy;
1250	return dwarfEncoding(dummy);
1251	}
1252
1253	#if defined(_LIBUNWIND_TARGET_X86_64)
1254	compact_unwind_encoding_t dwarfEncoding(Registers_x86_64 &) const {
1255	return UNWIND_X86_64_MODE_DWARF;
1256	}
1257	#endif
1258
1259	#if defined(_LIBUNWIND_TARGET_I386)
1260	compact_unwind_encoding_t dwarfEncoding(Registers_x86 &) const {
1261	return UNWIND_X86_MODE_DWARF;
1262	}
1263	#endif
1264
1265	#if defined(_LIBUNWIND_TARGET_PPC)
1266	compact_unwind_encoding_t dwarfEncoding(Registers_ppc &) const {
1267	return `0`;
1268	}
1269	#endif
1270
1271	#if defined(_LIBUNWIND_TARGET_PPC64)
1272	compact_unwind_encoding_t dwarfEncoding(Registers_ppc64 &) const {
1273	return `0`;
1274	}
1275	#endif
1276
1277	#if defined(_LIBUNWIND_TARGET_AARCH64)
1278	compact_unwind_encoding_t dwarfEncoding(Registers_arm64 &) const {
1279	return UNWIND_ARM64_MODE_DWARF;
1280	}
1281	#endif
1282
1283	#if defined(_LIBUNWIND_TARGET_ARM)
1284	compact_unwind_encoding_t dwarfEncoding(Registers_arm &) const {
1285	return `0`;
1286	}
1287	#endif
1288
1289	#if defined (_LIBUNWIND_TARGET_OR1K)
1290	compact_unwind_encoding_t dwarfEncoding(Registers_or1k &) const {
1291	return `0`;
1292	}
1293	#endif
1294
1295	#if defined (_LIBUNWIND_TARGET_HEXAGON)
1296	compact_unwind_encoding_t dwarfEncoding(Registers_hexagon &) const {
1297	return `0`;
1298	}
1299	#endif
1300
1301	#if defined (_LIBUNWIND_TARGET_MIPS_O32)
1302	compact_unwind_encoding_t dwarfEncoding(Registers_mips_o32 &) const {
1303	return `0`;
1304	}
1305	#endif
1306
1307	#if defined (_LIBUNWIND_TARGET_MIPS_NEWABI)
1308	compact_unwind_encoding_t dwarfEncoding(Registers_mips_newabi &) const {
1309	return `0`;
1310	}
1311	#endif
1312
1313	#if defined(_LIBUNWIND_TARGET_LOONGARCH)
1314	compact_unwind_encoding_t dwarfEncoding(Registers_loongarch &) const {
1315	return `0`;
1316	}
1317	#endif
1318
1319	#if defined(_LIBUNWIND_TARGET_SPARC)
1320	compact_unwind_encoding_t dwarfEncoding(Registers_sparc &) const { return `0`; }
1321	#endif
1322
1323	#if defined(_LIBUNWIND_TARGET_SPARC64)
1324	compact_unwind_encoding_t dwarfEncoding(Registers_sparc64 &) const {
1325	return `0`;
1326	}
1327	#endif
1328
1329	#if defined (_LIBUNWIND_TARGET_RISCV)
1330	compact_unwind_encoding_t dwarfEncoding(Registers_riscv &) const {
1331	return `0`;
1332	}
1333	#endif
1334
1335	#if defined (_LIBUNWIND_TARGET_S390X)
1336	compact_unwind_encoding_t dwarfEncoding(Registers_s390x &) const {
1337	return `0`;
1338	}
1339	#endif
1340
1341	#endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1342
1343	#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1344	// For runtime environments using SEH unwind data without Windows runtime
1345	// support.
1346	pint_t getLastPC() const { / FIXME: Implement / return `0`; }
1347	void setLastPC(pint_t pc) { / FIXME: Implement / }
1348	RUNTIME_FUNCTION lookUpSEHUnwindInfo(pint_t pc, pint_t base) {
1349	/ FIXME: Implement /
1350	*base = `0`;
1351	return nullptr;
1352	}
1353	bool getInfoFromSEH(pint_t pc);
1354	int stepWithSEHData() { / FIXME: Implement / return `0`; }
1355	#endif // defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1356
1357	#if defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
1358	bool getInfoFromTBTable(pint_t pc, R &registers);
1359	int stepWithTBTable(pint_t pc, tbtable *TBTable, R &registers,
1360	bool &isSignalFrame);
1361	int stepWithTBTableData() {
1362	return stepWithTBTable(reinterpret_cast<pint_t>(this->getReg(UNW_REG_IP)),
1363	reinterpret_cast<tbtable *>(_info.unwind_info),
1364	_registers, _isSignalFrame);
1365	}
1366	#endif // defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
1367
1368	A &_addressSpace;
1369	R _registers;
1370	unw_proc_info_t _info;
1371	bool _unwindInfoMissing;
1372	bool _isSignalFrame;
1373	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) \|\| \
1374	defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
1375	bool _isSigReturn = false;
1376	#endif
1377	#ifdef _LIBUNWIND_TRACE_RET_INJECT
1378	uint32_t _walkedFrames;
1379	#endif
1380	};
1381
1382
1383	template <typename A, typename R>
1384	UnwindCursor<A, R>::UnwindCursor(unw_context_t *context, A &as)
1385	: _addressSpace(as), _registers(context), _unwindInfoMissing(false),
1386	_isSignalFrame(false) {
1387	static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
1388	"UnwindCursor<> does not fit in unw_cursor_t");
1389	static_assert((alignof(UnwindCursor<A, R>) <= alignof(unw_cursor_t)),
1390	"UnwindCursor<> requires more alignment than unw_cursor_t");
1391	memset(s: static_cast<void >(&_info), c: `0`, n: sizeof*(_info));
1392	}
1393
1394	template <typename A, typename R>
1395	UnwindCursor<A, R>::UnwindCursor(A &as, void *)
1396	: _addressSpace(as), _unwindInfoMissing(false), _isSignalFrame(false) {
1397	memset(s: static_cast<void >(&_info), c: `0`, n: sizeof*(_info));
1398	// FIXME
1399	// fill in _registers from thread arg
1400	}
1401
1402
1403	template <typename A, typename R>
1404	bool UnwindCursor<A, R>::validReg(int regNum) {
1405	return _registers.validRegister(regNum);
1406	}
1407
1408	template <typename A, typename R>
1409	unw_word_t UnwindCursor<A, R>::getReg(int regNum) {
1410	return _registers.getRegister(regNum);
1411	}
1412
1413	template <typename A, typename R>
1414	void UnwindCursor<A, R>::setReg(int regNum, unw_word_t value) {
1415	_registers.setRegister(regNum, (typename A::pint_t)value);
1416	}
1417
1418	template <typename A, typename R>
1419	bool UnwindCursor<A, R>::validFloatReg(int regNum) {
1420	return _registers.validFloatRegister(regNum);
1421	}
1422
1423	template <typename A, typename R>
1424	unw_fpreg_t UnwindCursor<A, R>::getFloatReg(int regNum) {
1425	return _registers.getFloatRegister(regNum);
1426	}
1427
1428	template <typename A, typename R>
1429	void UnwindCursor<A, R>::setFloatReg(int regNum, unw_fpreg_t value) {
1430	_registers.setFloatRegister(regNum, value);
1431	}
1432
1433	template <typename A, typename R> void UnwindCursor<A, R>::jumpto() {
1434	#ifdef _LIBUNWIND_TRACE_RET_INJECT
1435	/*
1436
1437	The value of `_walkedFrames` is computed in `unwind_phase2` and represents the
1438	number of frames walked starting `unwind_phase2` to get to the landing pad.
1439
1440	```
1441	// uc is initialized by __unw_getcontext in the parent frame.
1442	// The first stack frame walked is unwind_phase2.
1443	unsigned framesWalked = 1;
1444	```
1445
1446	To that, we need to add the number of function calls in libunwind between
1447	`unwind_phase2` & `__libunwind_Registers_arm64_jumpto` which performs the long
1448	jump, to rebalance the execution flow.
1449
1450	```
1451	frame #0: libunwind.1.dylib`__libunwind_Registers_arm64_jumpto at UnwindRegistersRestore.S:646
1452	frame #1: libunwind.1.dylib`libunwind::Registers_arm64::returnto at Registers.hpp:2291:3
1453	frame #2: libunwind.1.dylib`libunwind::UnwindCursor<libunwind::LocalAddressSpace, libunwind::Registers_arm64>::jumpto at UnwindCursor.hpp:1474:14
1454	frame #3: libunwind.1.dylib`__unw_resume at libunwind.cpp:375:7
1455	frame #4: libunwind.1.dylib`__unw_resume_with_frames_walked at libunwind.cpp:363:10
1456	frame #5: libunwind.1.dylib`unwind_phase2 at UnwindLevel1.c:328:9
1457	frame #6: libunwind.1.dylib`_Unwind_RaiseException at UnwindLevel1.c:480:10
1458	frame #7: libc++abi.dylib`__cxa_throw at cxa_exception.cpp:295:5
1459	...
1460	```
1461
1462	If we look at the backtrace from `__libunwind_Registers_arm64_jumpto`, we see
1463	there are 5 frames on the stack to reach `unwind_phase2`. However, only 4 of
1464	them will never return, since `__libunwind_Registers_arm64_jumpto` returns
1465	back to the landing pad, so we need to subtract 1 to the number of
1466	`_EXTRA_LIBUNWIND_FRAMES_WALKED`.
1467	*/
1468
1469	static constexpr size_t _EXTRA_LIBUNWIND_FRAMES_WALKED = `5` - `1`;
1470	_registers.returnto(_walkedFrames + _EXTRA_LIBUNWIND_FRAMES_WALKED);
1471	#else
1472	_registers.jumpto();
1473	#endif
1474	}
1475
1476	#ifdef __arm__
1477	template <typename A, typename R> void UnwindCursor<A, R>::saveVFPAsX() {
1478	_registers.saveVFPAsX();
1479	}
1480	#endif
1481
1482	#ifdef _LIBUNWIND_TRACE_RET_INJECT
1483	template <typename A, typename R>
1484	void UnwindCursor<A, R>::setWalkedFrames(unsigned walkedFrames) {
1485	_walkedFrames = walkedFrames;
1486	}
1487	#endif
1488
1489	#ifdef _AIX
1490	template <typename A, typename R>
1491	uintptr_t UnwindCursor<A, R>::getDataRelBase() {
1492	return reinterpret_cast<uintptr_t>(_info.extra);
1493	}
1494	#endif
1495
1496	template <typename A, typename R>
1497	const char UnwindCursor<A, R>::getRegisterName(int* regNum) {
1498	return _registers.getRegisterName(regNum);
1499	}
1500
1501	template <typename A, typename R> bool UnwindCursor<A, R>::isSignalFrame() {
1502	return _isSignalFrame;
1503	}
1504
1505	#endif // defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1506
1507	#if defined(_LIBUNWIND_ARM_EHABI)
1508	template<typename A>
1509	struct EHABISectionIterator {
1510	typedef EHABISectionIterator _Self;
1511
1512	typedef typename A::pint_t value_type;
1513	typedef typename A::pint_t* pointer;
1514	typedef typename A::pint_t& reference;
1515	typedef size_t size_type;
1516	typedef size_t difference_type;
1517
1518	static _Self begin(A& addressSpace, const UnwindInfoSections& sects) {
1519	return _Self(addressSpace, sects, `0`);
1520	}
1521	static _Self end(A& addressSpace, const UnwindInfoSections& sects) {
1522	return _Self(addressSpace, sects,
1523	sects.arm_section_length / sizeof(EHABIIndexEntry));
1524	}
1525
1526	EHABISectionIterator(A& addressSpace, const UnwindInfoSections& sects, size_t i)
1527	: _i(i), _addressSpace(&addressSpace), _sects(&sects) {}
1528
1529	_Self& operator++() { ++_i; return *this; }
1530	_Self& operator+=(size_t a) { _i += a; return *this; }
1531	_Self& operator--() { assert(_i > `0`); --_i; return *this; }
1532	_Self& operator-=(size_t a) { assert(_i >= a); _i -= a; return *this; }
1533
1534	_Self operator+(size_t a) { _Self out = *this; out._i += a; return out; }
1535	_Self operator-(size_t a) { assert(_i >= a); _Self out = *this; out._i -= a; return out; }
1536
1537	size_t operator-(const _Self& other) const { return _i - other._i; }
1538
1539	bool operator==(const _Self& other) const {
1540	assert(_addressSpace == other._addressSpace);
1541	assert(_sects == other._sects);
1542	return _i == other._i;
1543	}
1544
1545	bool operator!=(const _Self& other) const {
1546	assert(_addressSpace == other._addressSpace);
1547	assert(_sects == other._sects);
1548	return _i != other._i;
1549	}
1550
1551	typename A::pint_t operator() const* { return functionAddress(); }
1552
1553	typename A::pint_t functionAddress() const {
1554	typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
1555	EHABIIndexEntry, _i, functionOffset);
1556	return indexAddr + signExtendPrel31(_addressSpace->get32(indexAddr));
1557	}
1558
1559	typename A::pint_t dataAddress() {
1560	typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
1561	EHABIIndexEntry, _i, data);
1562	return indexAddr;
1563	}
1564
1565	private:
1566	size_t _i;
1567	A* _addressSpace;
1568	const UnwindInfoSections* _sects;
1569	};
1570
1571	namespace {
1572
1573	template <typename A>
1574	EHABISectionIterator<A> EHABISectionUpperBound(
1575	EHABISectionIterator<A> first,
1576	EHABISectionIterator<A> last,
1577	typename A::pint_t value) {
1578	size_t len = last - first;
1579	while (len > `0`) {
1580	size_t l2 = len / `2`;
1581	EHABISectionIterator<A> m = first + l2;
1582	if (value < *m) {
1583	len = l2;
1584	} else {
1585	first = ++m;
1586	len -= l2 + `1`;
1587	}
1588	}
1589	return first;
1590	}
1591
1592	}
1593
1594	template <typename A, typename R>
1595	bool UnwindCursor<A, R>::getInfoFromEHABISection(
1596	pint_t pc,
1597	const UnwindInfoSections &sects) {
1598	EHABISectionIterator<A> begin =
1599	EHABISectionIterator<A>::begin(_addressSpace, sects);
1600	EHABISectionIterator<A> end =
1601	EHABISectionIterator<A>::end(_addressSpace, sects);
1602	if (begin == end)
1603	return false;
1604
1605	EHABISectionIterator<A> itNextPC = EHABISectionUpperBound(begin, end, pc);
1606	if (itNextPC == begin)
1607	return false;
1608	EHABISectionIterator<A> itThisPC = itNextPC - `1`;
1609
1610	pint_t thisPC = itThisPC.functionAddress();
1611	// If an exception is thrown from a function, corresponding to the last entry
1612	// in the table, we don't really know the function extent and have to choose a
1613	// value for nextPC. Choosing max() will allow the range check during trace to
1614	// succeed.
1615	pint_t nextPC = (itNextPC == end) ? UINTPTR_MAX : itNextPC.functionAddress();
1616	pint_t indexDataAddr = itThisPC.dataAddress();
1617
1618	if (indexDataAddr == `0`)
1619	return false;
1620
1621	uint32_t indexData = _addressSpace.get32(indexDataAddr);
1622	if (indexData == UNW_EXIDX_CANTUNWIND)
1623	return false;
1624
1625	// If the high bit is set, the exception handling table entry is inline inside
1626	// the index table entry on the second word (aka \|indexDataAddr\|). Otherwise,
1627	// the table points at an offset in the exception handling table (section 5
1628	// EHABI).
1629	pint_t exceptionTableAddr;
1630	uint32_t exceptionTableData;
1631	bool isSingleWordEHT;
1632	if (indexData & `0x80000000`) {
1633	exceptionTableAddr = indexDataAddr;
1634	// TODO(ajwong): Should this data be 0?
1635	exceptionTableData = indexData;
1636	isSingleWordEHT = true;
1637	} else {
1638	exceptionTableAddr = indexDataAddr + signExtendPrel31(indexData);
1639	exceptionTableData = _addressSpace.get32(exceptionTableAddr);
1640	isSingleWordEHT = false;
1641	}
1642
1643	// Now we know the 3 things:
1644	// exceptionTableAddr -- exception handler table entry.
1645	// exceptionTableData -- the data inside the first word of the eht entry.
1646	// isSingleWordEHT -- whether the entry is in the index.
1647	unw_word_t personalityRoutine = `0xbadf00d`;
1648	bool scope32 = false;
1649	uintptr_t lsda;
1650
1651	// If the high bit in the exception handling table entry is set, the entry is
1652	// in compact form (section 6.3 EHABI).
1653	if (exceptionTableData & `0x80000000`) {
1654	// Grab the index of the personality routine from the compact form.
1655	uint32_t choice = (exceptionTableData & `0x0f000000`) >> `24`;
1656	uint32_t extraWords = `0`;
1657	switch (choice) {
1658	case `0`:
1659	personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr0;
1660	extraWords = `0`;
1661	scope32 = false;
1662	lsda = isSingleWordEHT ? `0` : (exceptionTableAddr + `4`);
1663	break;
1664	case `1`:
1665	personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr1;
1666	extraWords = (exceptionTableData & `0x00ff0000`) >> `16`;
1667	scope32 = false;
1668	lsda = exceptionTableAddr + (extraWords + `1`) * `4`;
1669	break;
1670	case `2`:
1671	personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr2;
1672	extraWords = (exceptionTableData & `0x00ff0000`) >> `16`;
1673	scope32 = true;
1674	lsda = exceptionTableAddr + (extraWords + `1`) * `4`;
1675	break;
1676	default:
1677	_LIBUNWIND_ABORT("unknown personality routine");
1678	return false;
1679	}
1680
1681	if (isSingleWordEHT) {
1682	if (extraWords != `0`) {
1683	_LIBUNWIND_ABORT("index inlined table detected but pr function "
1684	"requires extra words");
1685	return false;
1686	}
1687	}
1688	} else {
1689	pint_t personalityAddr =
1690	exceptionTableAddr + signExtendPrel31(exceptionTableData);
1691	personalityRoutine = personalityAddr;
1692
1693	// ARM EHABI # 6.2, # 9.2
1694	//
1695	// +---- ehtp
1696	// v
1697	// +--------------------------------------+
1698	// \| +--------+--------+--------+-------+ \|
1699	// \| \|0\| prel31 to personalityRoutine \| \|
1700	// \| +--------+--------+--------+-------+ \|
1701	// \| \| N \| unwind opcodes \| \| <-- UnwindData
1702	// \| +--------+--------+--------+-------+ \|
1703	// \| \| Word 2 unwind opcodes \| \|
1704	// \| +--------+--------+--------+-------+ \|
1705	// \| ... \|
1706	// \| +--------+--------+--------+-------+ \|
1707	// \| \| Word N unwind opcodes \| \|
1708	// \| +--------+--------+--------+-------+ \|
1709	// \| \| LSDA \| \| <-- lsda
1710	// \| \| ... \| \|
1711	// \| +--------+--------+--------+-------+ \|
1712	// +--------------------------------------+
1713
1714	uint32_t UnwindData = reinterpret_cast<uint32_t>(exceptionTableAddr) + `1`;
1715	uint32_t FirstDataWord = *UnwindData;
1716	size_t N = ((FirstDataWord >> `24`) & `0xff`);
1717	size_t NDataWords = N + `1`;
1718	lsda = reinterpret_cast<uintptr_t>(UnwindData + NDataWords);
1719	}
1720
1721	_info.start_ip = thisPC;
1722	_info.end_ip = nextPC;
1723	_info.handler = personalityRoutine;
1724	_info.unwind_info = exceptionTableAddr;
1725	_info.lsda = lsda;
1726	// flags is pr_cache.additional. See EHABI #7.2 for definition of bit 0.
1727	_info.flags = (isSingleWordEHT ? `1` : `0`) \| (scope32 ? `0x2` : `0`); // Use enum?
1728
1729	return true;
1730	}
1731	#endif
1732
1733	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1734	template <typename A, typename R>
1735	bool UnwindCursor<A, R>::getInfoFromFdeCie(
1736	const typename CFI_Parser<A>::FDE_Info &fdeInfo,
1737	const typename CFI_Parser<A>::CIE_Info &cieInfo,
1738	typename R::link_hardened_reg_arg_t pc, uintptr_t dso_base) {
1739	typename CFI_Parser<A>::PrologInfo prolog;
1740	if (CFI_Parser<A>::template parseFDEInstructions<R>(
1741	_addressSpace, fdeInfo, cieInfo, pc, R::getArch(), &prolog)) {
1742	// Save off parsed FDE info
1743	_info.start_ip = fdeInfo.pcStart;
1744	_info.end_ip = fdeInfo.pcEnd;
1745	_info.lsda = fdeInfo.lsda;
1746	_info.handler = cieInfo.personality;
1747	// Some frameless functions need SP altered when resuming in function, so
1748	// propagate spExtraArgSize.
1749	_info.gp = prolog.spExtraArgSize;
1750	_info.flags = `0`;
1751	_info.format = dwarfEncoding();
1752	_info.unwind_info = fdeInfo.fdeStart;
1753	_info.unwind_info_size = static_cast<uint32_t>(fdeInfo.fdeLength);
1754	_info.extra = static_cast<unw_word_t>(dso_base);
1755	return true;
1756	}
1757	return false;
1758	}
1759
1760	template <typename A, typename R>
1761	bool UnwindCursor<A, R>::getInfoFromDwarfSection(
1762	typename R::link_hardened_reg_arg_t pc, const UnwindInfoSections &sects,
1763	uint32_t fdeSectionOffsetHint) {
1764	typename CFI_Parser<A>::FDE_Info fdeInfo;
1765	typename CFI_Parser<A>::CIE_Info cieInfo;
1766	bool foundFDE = false;
1767	bool foundInCache = false;
1768	// If compact encoding table gave offset into dwarf section, go directly there
1769	if (fdeSectionOffsetHint != `0`) {
1770	foundFDE = CFI_Parser<A>::template findFDE<R>(
1771	_addressSpace, pc, sects.dwarf_section, sects.dwarf_section_length,
1772	sects.dwarf_section + fdeSectionOffsetHint, &fdeInfo, &cieInfo);
1773	}
1774	#if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
1775	if (!foundFDE && (sects.dwarf_index_section != `0`)) {
1776	foundFDE = EHHeaderParser<A>::template findFDE<R>(
1777	_addressSpace, pc, sects.dwarf_index_section,
1778	(uint32_t)sects.dwarf_index_section_length, &fdeInfo, &cieInfo);
1779	}
1780	#endif
1781	if (!foundFDE) {
1782	// otherwise, search cache of previously found FDEs.
1783	pint_t cachedFDE =
1784	DwarfFDECache<A>::template findFDE<R>(sects.dso_base, pc);
1785	if (cachedFDE != `0`) {
1786	foundFDE = CFI_Parser<A>::template findFDE<R>(
1787	_addressSpace, pc, sects.dwarf_section, sects.dwarf_section_length,
1788	cachedFDE, &fdeInfo, &cieInfo);
1789	foundInCache = foundFDE;
1790	}
1791	}
1792	if (!foundFDE) {
1793	// Still not found, do full scan of __eh_frame section.
1794	foundFDE = CFI_Parser<A>::template findFDE<R>(
1795	_addressSpace, pc, sects.dwarf_section, sects.dwarf_section_length, `0`,
1796	&fdeInfo, &cieInfo);
1797	}
1798	if (foundFDE) {
1799	if (getInfoFromFdeCie(fdeInfo, cieInfo, pc, dso_base: sects.dso_base)) {
1800	// Add to cache (to make next lookup faster) if we had no hint
1801	// and there was no index.
1802	if (!foundInCache && (fdeSectionOffsetHint == `0`)) {
1803	#if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
1804	if (sects.dwarf_index_section == `0`)
1805	#endif
1806	DwarfFDECache<A>::add(sects.dso_base, fdeInfo.pcStart, fdeInfo.pcEnd,
1807	fdeInfo.fdeStart);
1808	}
1809	return true;
1810	}
1811	}
1812	//_LIBUNWIND_DEBUG_LOG("can't find/use FDE for pc=0x%llX", (uint64_t)pc);
1813	return false;
1814	}
1815	#endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1816
1817
1818	#if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1819	template <typename A, typename R>
1820	bool UnwindCursor<A, R>::getInfoFromCompactEncodingSection(
1821	typename R::link_hardened_reg_arg_t pc, const UnwindInfoSections &sects) {
1822	const bool log = false;
1823	if (log)
1824	fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX, mh=0x%llX)\n",
1825	(uint64_t)pc, (uint64_t)sects.dso_base);
1826
1827	const UnwindSectionHeader<A> sectionHeader(_addressSpace,
1828	sects.compact_unwind_section);
1829	if (sectionHeader.version() != UNWIND_SECTION_VERSION)
1830	return false;
1831
1832	// do a binary search of top level index to find page with unwind info
1833	pint_t targetFunctionOffset = pc - sects.dso_base;
1834	const UnwindSectionIndexArray<A> topIndex(_addressSpace,
1835	sects.compact_unwind_section
1836	+ sectionHeader.indexSectionOffset());
1837	uint32_t low = `0`;
1838	uint32_t high = sectionHeader.indexCount();
1839	uint32_t last = high - `1`;
1840	while (low < high) {
1841	uint32_t mid = (low + high) / `2`;
1842	//if ( log ) fprintf(stderr, "\tmid=%d, low=%d, high=%d, mid=0x%08X\n",*
1843	//mid, low, high, topIndex.functionOffset(mid));
1844	if (topIndex.functionOffset(mid) <= targetFunctionOffset) {
1845	if ((mid == last) \|\|
1846	(topIndex.functionOffset(mid + `1`) > targetFunctionOffset)) {
1847	low = mid;
1848	break;
1849	} else {
1850	low = mid + `1`;
1851	}
1852	} else {
1853	high = mid;
1854	}
1855	}
1856	const uint32_t firstLevelFunctionOffset = topIndex.functionOffset(low);
1857	const uint32_t firstLevelNextPageFunctionOffset =
1858	topIndex.functionOffset(low + `1`);
1859	const pint_t secondLevelAddr =
1860	sects.compact_unwind_section + topIndex.secondLevelPagesSectionOffset(low);
1861	const pint_t lsdaArrayStartAddr =
1862	sects.compact_unwind_section + topIndex.lsdaIndexArraySectionOffset(low);
1863	const pint_t lsdaArrayEndAddr =
1864	sects.compact_unwind_section + topIndex.lsdaIndexArraySectionOffset(low+`1`);
1865	if (log)
1866	fprintf(stderr, "\tfirst level search for result index=%d "
1867	"to secondLevelAddr=0x%llX\n",
1868	low, (uint64_t) secondLevelAddr);
1869	// do a binary search of second level page index
1870	uint32_t encoding = `0`;
1871	pint_t funcStart = `0`;
1872	pint_t funcEnd = `0`;
1873	pint_t lsda = `0`;
1874	pint_t personality = `0`;
1875	uint32_t pageKind = _addressSpace.get32(secondLevelAddr);
1876	if (pageKind == UNWIND_SECOND_LEVEL_REGULAR) {
1877	// regular page
1878	UnwindSectionRegularPageHeader<A> pageHeader(_addressSpace,
1879	secondLevelAddr);
1880	UnwindSectionRegularArray<A> pageIndex(
1881	_addressSpace, secondLevelAddr + pageHeader.entryPageOffset());
1882	// binary search looks for entry with e where index[e].offset <= pc <
1883	// index[e+1].offset
1884	if (log)
1885	fprintf(stderr, "\tbinary search for targetFunctionOffset=0x%08llX in "
1886	"regular page starting at secondLevelAddr=0x%llX\n",
1887	(uint64_t) targetFunctionOffset, (uint64_t) secondLevelAddr);
1888	low = `0`;
1889	high = pageHeader.entryCount();
1890	while (low < high) {
1891	uint32_t mid = (low + high) / `2`;
1892	if (pageIndex.functionOffset(mid) <= targetFunctionOffset) {
1893	if (mid == (uint32_t)(pageHeader.entryCount() - `1`)) {
1894	// at end of table
1895	low = mid;
1896	funcEnd = firstLevelNextPageFunctionOffset + sects.dso_base;
1897	break;
1898	} else if (pageIndex.functionOffset(mid + `1`) > targetFunctionOffset) {
1899	// next is too big, so we found it
1900	low = mid;
1901	funcEnd = pageIndex.functionOffset(low + `1`) + sects.dso_base;
1902	break;
1903	} else {
1904	low = mid + `1`;
1905	}
1906	} else {
1907	high = mid;
1908	}
1909	}
1910	encoding = pageIndex.encoding(low);
1911	funcStart = pageIndex.functionOffset(low) + sects.dso_base;
1912	if (pc < funcStart) {
1913	if (log)
1914	fprintf(
1915	stderr,
1916	"\tpc not in table, pc=0x%llX, funcStart=0x%llX, funcEnd=0x%llX\n",
1917	(uint64_t) pc, (uint64_t) funcStart, (uint64_t) funcEnd);
1918	return false;
1919	}
1920	if (pc > funcEnd) {
1921	if (log)
1922	fprintf(
1923	stderr,
1924	"\tpc not in table, pc=0x%llX, funcStart=0x%llX, funcEnd=0x%llX\n",
1925	(uint64_t) pc, (uint64_t) funcStart, (uint64_t) funcEnd);
1926	return false;
1927	}
1928	} else if (pageKind == UNWIND_SECOND_LEVEL_COMPRESSED) {
1929	// compressed page
1930	UnwindSectionCompressedPageHeader<A> pageHeader(_addressSpace,
1931	secondLevelAddr);
1932	UnwindSectionCompressedArray<A> pageIndex(
1933	_addressSpace, secondLevelAddr + pageHeader.entryPageOffset());
1934	const uint32_t targetFunctionPageOffset =
1935	(uint32_t)(targetFunctionOffset - firstLevelFunctionOffset);
1936	// binary search looks for entry with e where index[e].offset <= pc <
1937	// index[e+1].offset
1938	if (log)
1939	fprintf(stderr, "\tbinary search of compressed page starting at "
1940	"secondLevelAddr=0x%llX\n",
1941	(uint64_t) secondLevelAddr);
1942	low = `0`;
1943	last = pageHeader.entryCount() - `1`;
1944	high = pageHeader.entryCount();
1945	while (low < high) {
1946	uint32_t mid = (low + high) / `2`;
1947	if (pageIndex.functionOffset(mid) <= targetFunctionPageOffset) {
1948	if ((mid == last) \|\|
1949	(pageIndex.functionOffset(mid + `1`) > targetFunctionPageOffset)) {
1950	low = mid;
1951	break;
1952	} else {
1953	low = mid + `1`;
1954	}
1955	} else {
1956	high = mid;
1957	}
1958	}
1959	funcStart = pageIndex.functionOffset(low) + firstLevelFunctionOffset
1960	+ sects.dso_base;
1961	if (low < last)
1962	funcEnd =
1963	pageIndex.functionOffset(low + `1`) + firstLevelFunctionOffset
1964	+ sects.dso_base;
1965	else
1966	funcEnd = firstLevelNextPageFunctionOffset + sects.dso_base;
1967	if (pc < funcStart) {
1968	_LIBUNWIND_DEBUG_LOG("malformed __unwind_info, pc=0x%llX "
1969	"not in second level compressed unwind table. "
1970	"funcStart=0x%llX",
1971	(uint64_t) pc, (uint64_t) funcStart);
1972	return false;
1973	}
1974	if (pc > funcEnd) {
1975	_LIBUNWIND_DEBUG_LOG("malformed __unwind_info, pc=0x%llX "
1976	"not in second level compressed unwind table. "
1977	"funcEnd=0x%llX",
1978	(uint64_t) pc, (uint64_t) funcEnd);
1979	return false;
1980	}
1981	uint16_t encodingIndex = pageIndex.encodingIndex(low);
1982	if (encodingIndex < sectionHeader.commonEncodingsArrayCount()) {
1983	// encoding is in common table in section header
1984	encoding = _addressSpace.get32(
1985	sects.compact_unwind_section +
1986	sectionHeader.commonEncodingsArraySectionOffset() +
1987	encodingIndex * sizeof(uint32_t));
1988	} else {
1989	// encoding is in page specific table
1990	uint16_t pageEncodingIndex =
1991	encodingIndex - (uint16_t)sectionHeader.commonEncodingsArrayCount();
1992	encoding = _addressSpace.get32(secondLevelAddr +
1993	pageHeader.encodingsPageOffset() +
1994	pageEncodingIndex * sizeof(uint32_t));
1995	}
1996	} else {
1997	_LIBUNWIND_DEBUG_LOG(
1998	"malformed __unwind_info at 0x%0llX bad second level page",
1999	(uint64_t)sects.compact_unwind_section);
2000	return false;
2001	}
2002
2003	// look up LSDA, if encoding says function has one
2004	if (encoding & UNWIND_HAS_LSDA) {
2005	UnwindSectionLsdaArray<A> lsdaIndex(_addressSpace, lsdaArrayStartAddr);
2006	uint32_t funcStartOffset = (uint32_t)(funcStart - sects.dso_base);
2007	low = `0`;
2008	high = (uint32_t)(lsdaArrayEndAddr - lsdaArrayStartAddr) /
2009	sizeof(unwind_info_section_header_lsda_index_entry);
2010	// binary search looks for entry with exact match for functionOffset
2011	if (log)
2012	fprintf(stderr,
2013	"\tbinary search of lsda table for targetFunctionOffset=0x%08X\n",
2014	funcStartOffset);
2015	while (low < high) {
2016	uint32_t mid = (low + high) / `2`;
2017	if (lsdaIndex.functionOffset(mid) == funcStartOffset) {
2018	lsda = lsdaIndex.lsdaOffset(mid) + sects.dso_base;
2019	break;
2020	} else if (lsdaIndex.functionOffset(mid) < funcStartOffset) {
2021	low = mid + `1`;
2022	} else {
2023	high = mid;
2024	}
2025	}
2026	if (lsda == `0`) {
2027	_LIBUNWIND_DEBUG_LOG("found encoding 0x%08X with HAS_LSDA bit set for "
2028	"pc=0x%0llX, but lsda table has no entry",
2029	encoding, (uint64_t) pc);
2030	return false;
2031	}
2032	}
2033
2034	// extract personality routine, if encoding says function has one
2035	uint32_t personalityIndex = (encoding & UNWIND_PERSONALITY_MASK) >>
2036	(__builtin_ctz(UNWIND_PERSONALITY_MASK));
2037	if (personalityIndex != `0`) {
2038	--personalityIndex; // change 1-based to zero-based index
2039	if (personalityIndex >= sectionHeader.personalityArrayCount()) {
2040	_LIBUNWIND_DEBUG_LOG("found encoding 0x%08X with personality index %d, "
2041	"but personality table has only %d entries",
2042	encoding, personalityIndex,
2043	sectionHeader.personalityArrayCount());
2044	return false;
2045	}
2046	int32_t personalityDelta = (int32_t)_addressSpace.get32(
2047	sects.compact_unwind_section +
2048	sectionHeader.personalityArraySectionOffset() +
2049	personalityIndex * sizeof(uint32_t));
2050	pint_t personalityPointer = sects.dso_base + (pint_t)personalityDelta;
2051	personality = _addressSpace.getP(personalityPointer);
2052	#if defined(_LIBUNWIND_TARGET_AARCH64_AUTHENTICATED_UNWINDING)
2053	// The GOT for the personality function was signed address authenticated.
2054	// Resign it as a regular function pointer.
2055	const auto discriminator = ptrauth_blend_discriminator(
2056	&_info.handler, __ptrauth_unwind_upi_handler_disc);
2057	void *signedPtr = ptrauth_auth_and_resign(
2058	(void *)personality, ptrauth_key_function_pointer, personalityPointer,
2059	ptrauth_key_function_pointer, discriminator);
2060	personality = (__typeof(personality))signedPtr;
2061	#endif
2062	if (log)
2063	fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX), "
2064	"personalityDelta=0x%08X, personality=0x%08llX\n",
2065	(uint64_t) pc, personalityDelta, (uint64_t) personality);
2066	}
2067
2068	if (log)
2069	fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX), "
2070	"encoding=0x%08X, lsda=0x%08llX for funcStart=0x%llX\n",
2071	(uint64_t) pc, encoding, (uint64_t) lsda, (uint64_t) funcStart);
2072	_info.start_ip = funcStart;
2073	_info.end_ip = funcEnd;
2074	_info.lsda = lsda;
2075	// We use memmove to copy the personality function as we have already manually
2076	// re-signed the pointer, and assigning directly will attempt to incorrectly
2077	// sign the already signed value.
2078	memmove(reinterpret_cast<void *>(&_info.handler),
2079	reinterpret_cast<void >(&personality), sizeof*(personality));
2080	_info.gp = `0`;
2081	_info.flags = `0`;
2082	_info.format = encoding;
2083	_info.unwind_info = `0`;
2084	_info.unwind_info_size = `0`;
2085	_info.extra = sects.dso_base;
2086	return true;
2087	}
2088	#endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
2089
2090
2091	#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
2092	template <typename A, typename R>
2093	bool UnwindCursor<A, R>::getInfoFromSEH(pint_t pc) {
2094	pint_t base;
2095	RUNTIME_FUNCTION *unwindEntry = lookUpSEHUnwindInfo(pc, &base);
2096	if (!unwindEntry) {
2097	_LIBUNWIND_DEBUG_LOG("\tpc not in table, pc=0x%llX", (uint64_t) pc);
2098	return false;
2099	}
2100	_info.gp = `0`;
2101	_info.flags = `0`;
2102	_info.format = `0`;
2103	_info.unwind_info_size = sizeof(RUNTIME_FUNCTION);
2104	_info.unwind_info = reinterpret_cast<unw_word_t>(unwindEntry);
2105	_info.extra = base;
2106	_info.start_ip = base + unwindEntry->BeginAddress;
2107	#ifdef _LIBUNWIND_TARGET_X86_64
2108	_info.end_ip = base + unwindEntry->EndAddress;
2109	// Only fill in the handler and LSDA if they're stale.
2110	if (pc != getLastPC()) {
2111	UNWIND_INFO xdata = reinterpret_cast<UNWIND_INFO >(base + unwindEntry->UnwindData);
2112	if (xdata->Flags & (UNW_FLAG_EHANDLER\|UNW_FLAG_UHANDLER)) {
2113	// The personality is given in the UNWIND_INFO itself. The LSDA immediately
2114	// follows the UNWIND_INFO. (This follows how both Clang and MSVC emit
2115	// these structures.)
2116	// N.B. UNWIND_INFO structs are DWORD-aligned.
2117	uint32_t lastcode = (xdata->CountOfCodes + `1`) & ~`1`;
2118	const uint32_t handler = reinterpret_cast<uint32_t >(&xdata->UnwindCodes[lastcode]);
2119	_info.lsda = reinterpret_cast<unw_word_t>(handler+`1`);
2120	_dispContext.HandlerData = reinterpret_cast<void *>(_info.lsda);
2121	_dispContext.LanguageHandler =
2122	reinterpret_cast<EXCEPTION_ROUTINE >(base + handler);
2123	if (*handler) {
2124	_info.handler = reinterpret_cast<unw_word_t>(__libunwind_seh_personality);
2125	} else
2126	_info.handler = `0`;
2127	} else {
2128	_info.lsda = `0`;
2129	_info.handler = `0`;
2130	}
2131	}
2132	#elif defined(_LIBUNWIND_TARGET_AARCH64) \|\| defined(_LIBUNWIND_TARGET_ARM)
2133
2134	#if defined(_LIBUNWIND_TARGET_AARCH64)
2135	#define FUNC_LENGTH_UNIT 4
2136	#define XDATA_TYPE IMAGE_ARM64_RUNTIME_FUNCTION_ENTRY_XDATA
2137	#else
2138	#define FUNC_LENGTH_UNIT 2
2139	#define XDATA_TYPE UNWIND_INFO_ARM
2140	#endif
2141	if (unwindEntry->Flag != `0`) { // Packed unwind info
2142	_info.end_ip =
2143	_info.start_ip + unwindEntry->FunctionLength * FUNC_LENGTH_UNIT;
2144	// Only fill in the handler and LSDA if they're stale.
2145	if (pc != getLastPC()) {
2146	// Packed unwind info doesn't have an exception handler.
2147	_info.lsda = `0`;
2148	_info.handler = `0`;
2149	}
2150	} else {
2151	XDATA_TYPE *xdata =
2152	reinterpret_cast<XDATA_TYPE *>(base + unwindEntry->UnwindData);
2153	_info.end_ip = _info.start_ip + xdata->FunctionLength * FUNC_LENGTH_UNIT;
2154	// Only fill in the handler and LSDA if they're stale.
2155	if (pc != getLastPC()) {
2156	if (xdata->ExceptionDataPresent) {
2157	uint32_t offset = `1`; // The main xdata
2158	uint32_t codeWords = xdata->CodeWords;
2159	uint32_t epilogScopes = xdata->EpilogCount;
2160	if (xdata->EpilogCount == `0` && xdata->CodeWords == `0`) {
2161	// The extension word has got the same layout for both ARM and ARM64
2162	uint32_t extensionWord = reinterpret_cast<uint32_t *>(xdata)[`1`];
2163	codeWords = (extensionWord >> `16`) & `0xff`;
2164	epilogScopes = extensionWord & `0xffff`;
2165	offset++;
2166	}
2167	if (!xdata->EpilogInHeader)
2168	offset += epilogScopes;
2169	offset += codeWords;
2170	uint32_t *exceptionHandlerInfo =
2171	reinterpret_cast<uint32_t *>(xdata) + offset;
2172	_dispContext.HandlerData = &exceptionHandlerInfo[`1`];
2173	_dispContext.LanguageHandler = reinterpret_cast<EXCEPTION_ROUTINE *>(
2174	base + exceptionHandlerInfo[`0`]);
2175	_info.lsda = reinterpret_cast<unw_word_t>(_dispContext.HandlerData);
2176	if (exceptionHandlerInfo[`0`])
2177	_info.handler =
2178	reinterpret_cast<unw_word_t>(__libunwind_seh_personality);
2179	else
2180	_info.handler = `0`;
2181	} else {
2182	_info.lsda = `0`;
2183	_info.handler = `0`;
2184	}
2185	}
2186	}
2187	#endif
2188	setLastPC(pc);
2189	return true;
2190	}
2191	#endif
2192
2193	#if defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
2194	// Masks for traceback table field xtbtable.
2195	enum xTBTableMask : uint8_t {
2196	reservedBit = `0x02`, // The traceback table was incorrectly generated if set
2197	// (see comments in function getInfoFromTBTable().
2198	ehInfoBit = `0x08` // Exception handling info is present if set
2199	};
2200
2201	enum frameType : unw_word_t {
2202	frameWithXLEHStateTable = `0`,
2203	frameWithEHInfo = `1`
2204	};
2205
2206	extern "C" {
2207	typedef _Unwind_Reason_Code __xlcxx_personality_v0_t(int, _Unwind_Action,
2208	uint64_t,
2209	_Unwind_Exception *,
2210	struct _Unwind_Context *);
2211	}
2212
2213	static __xlcxx_personality_v0_t *xlcPersonalityV0;
2214	static RWMutex xlcPersonalityV0InitLock;
2215
2216	template <typename A, typename R>
2217	bool UnwindCursor<A, R>::getInfoFromTBTable(pint_t pc, R &registers) {
2218	uint32_t p = reinterpret_cast<uint32_t >(pc);
2219
2220	// Keep looking forward until a word of 0 is found. The traceback
2221	// table starts at the following word.
2222	while (*p)
2223	++p;
2224	tbtable TBTable = reinterpret_cast<tbtable >(p + `1`);
2225
2226	if (_LIBUNWIND_TRACING_UNWINDING) {
2227	char functionBuf[`512`];
2228	const char *functionName = functionBuf;
2229	unw_word_t offset;
2230	if (!getFunctionName(functionBuf, sizeof(functionBuf), &offset)) {
2231	functionName = ".anonymous.";
2232	}
2233	_LIBUNWIND_TRACE_UNWINDING("%s: Look up traceback table of func=%s at %p",
2234	__func__, functionName,
2235	reinterpret_cast<void *>(TBTable));
2236	}
2237
2238	// If the traceback table does not contain necessary info, bypass this frame.
2239	if (!TBTable->tb.has_tboff)
2240	return false;
2241
2242	// Structure tbtable_ext contains important data we are looking for.
2243	p = reinterpret_cast<uint32_t *>(&TBTable->tb_ext);
2244
2245	// Skip field parminfo if it exists.
2246	if (TBTable->tb.fixedparms \|\| TBTable->tb.floatparms)
2247	++p;
2248
2249	// p now points to tb_offset, the offset from start of function to TB table.
2250	unw_word_t start_ip =
2251	reinterpret_cast<unw_word_t>(TBTable) - p - sizeof*(uint32_t);
2252	unw_word_t end_ip = reinterpret_cast<unw_word_t>(TBTable);
2253	++p;
2254
2255	_LIBUNWIND_TRACE_UNWINDING("start_ip=%p, end_ip=%p\n",
2256	reinterpret_cast<void *>(start_ip),
2257	reinterpret_cast<void *>(end_ip));
2258
2259	// Skip field hand_mask if it exists.
2260	if (TBTable->tb.int_hndl)
2261	++p;
2262
2263	unw_word_t lsda = `0`;
2264	unw_word_t handler = `0`;
2265	unw_word_t flags = frameType::frameWithXLEHStateTable;
2266
2267	if (TBTable->tb.lang == TB_CPLUSPLUS && TBTable->tb.has_ctl) {
2268	// State table info is available. The ctl_info field indicates the
2269	// number of CTL anchors. There should be only one entry for the C++
2270	// state table.
2271	assert(*p == `1` && "libunwind: there must be only one ctl_info entry");
2272	++p;
2273	// p points to the offset of the state table into the stack.
2274	pint_t stateTableOffset = *p++;
2275
2276	int framePointerReg;
2277
2278	// Skip fields name_len and name if exist.
2279	if (TBTable->tb.name_present) {
2280	const uint16_t name_len = (reinterpret_cast<uint16_t >(p));
2281	p = reinterpret_cast<uint32_t >(reinterpret_cast<char* *>(p) + name_len +
2282	sizeof(uint16_t));
2283	}
2284
2285	if (TBTable->tb.uses_alloca)
2286	framePointerReg = (reinterpret_cast<char* *>(p));
2287	else
2288	framePointerReg = `1`; // default frame pointer == SP
2289
2290	_LIBUNWIND_TRACE_UNWINDING(
2291	"framePointerReg=%d, framePointer=%p, "
2292	"stateTableOffset=%#lx\n",
2293	framePointerReg,
2294	reinterpret_cast<void *>(_registers.getRegister(framePointerReg)),
2295	stateTableOffset);
2296	lsda = _registers.getRegister(framePointerReg) + stateTableOffset;
2297
2298	// Since the traceback table generated by the legacy XLC++ does not
2299	// provide the location of the personality for the state table,
2300	// function __xlcxx_personality_v0(), which is the personality for the state
2301	// table and is exported from libc++abi, is directly assigned as the
2302	// handler here. When a legacy XLC++ frame is encountered, the symbol
2303	// is resolved dynamically using dlopen() to avoid a hard dependency of
2304	// libunwind on libc++abi in cases such as non-C++ applications.
2305
2306	// Resolve the function pointer to the state table personality if it has
2307	// not already been done.
2308	if (xlcPersonalityV0 == NULL) {
2309	xlcPersonalityV0InitLock.lock();
2310	if (xlcPersonalityV0 == NULL) {
2311	// Resolve __xlcxx_personality_v0 using dlopen().
2312	const char *libcxxabi = "libc++abi.a(libc++abi.so.1)";
2313	void *libHandle;
2314	// The AIX dlopen() sets errno to 0 when it is successful, which
2315	// clobbers the value of errno from the user code. This is an AIX
2316	// bug because according to POSIX it should not set errno to 0. To
2317	// workaround before AIX fixes the bug, errno is saved and restored.
2318	int saveErrno = errno;
2319	libHandle = dlopen(libcxxabi, RTLD_MEMBER \| RTLD_NOW);
2320	if (libHandle == NULL) {
2321	_LIBUNWIND_TRACE_UNWINDING("dlopen() failed with errno=%d\n", errno);
2322	assert(`0` && "dlopen() failed");
2323	}
2324	xlcPersonalityV0 = reinterpret_cast<__xlcxx_personality_v0_t *>(
2325	dlsym(libHandle, "__xlcxx_personality_v0"));
2326	if (xlcPersonalityV0 == NULL) {
2327	_LIBUNWIND_TRACE_UNWINDING("dlsym() failed with errno=%d\n", errno);
2328	dlclose(libHandle);
2329	assert(`0` && "dlsym() failed");
2330	}
2331	errno = saveErrno;
2332	}
2333	xlcPersonalityV0InitLock.unlock();
2334	}
2335	handler = reinterpret_cast<unw_word_t>(xlcPersonalityV0);
2336	_LIBUNWIND_TRACE_UNWINDING("State table: LSDA=%p, Personality=%p\n",
2337	reinterpret_cast<void *>(lsda),
2338	reinterpret_cast<void *>(handler));
2339	} else if (TBTable->tb.longtbtable) {
2340	// This frame has the traceback table extension. Possible cases are
2341	// 1) a C++ frame that has the 'eh_info' structure; 2) a C++ frame that
2342	// is not EH aware; or, 3) a frame of other languages. We need to figure out
2343	// if the traceback table extension contains the 'eh_info' structure.
2344	//
2345	// We also need to deal with the complexity arising from some XL compiler
2346	// versions use the wrong ordering of 'longtbtable' and 'has_vec' bits
2347	// where the 'longtbtable' bit is meant to be the 'has_vec' bit and vice
2348	// versa. For frames of code generated by those compilers, the 'longtbtable'
2349	// bit may be set but there isn't really a traceback table extension.
2350	//
2351	// In </usr/include/sys/debug.h>, there is the following definition of
2352	// 'struct tbtable_ext'. It is not really a structure but a dummy to
2353	// collect the description of optional parts of the traceback table.
2354	//
2355	// struct tbtable_ext {
2356	// ...
2357	// char alloca_reg; / Register for alloca automatic storage /
2358	// struct vec_ext vec_ext; / Vector extension (if has_vec is set) /
2359	// unsigned char xtbtable; / More tbtable fields, if longtbtable is set/
2360	// };
2361	//
2362	// Depending on how the 'has_vec'/'longtbtable' bit is interpreted, the data
2363	// following 'alloca_reg' can be treated either as 'struct vec_ext' or
2364	// 'unsigned char xtbtable'. 'xtbtable' bits are defined in
2365	// </usr/include/sys/debug.h> as flags. The 7th bit '0x02' is currently
2366	// unused and should not be set. 'struct vec_ext' is defined in
2367	// </usr/include/sys/debug.h> as follows:
2368	//
2369	// struct vec_ext {
2370	// unsigned vr_saved:6; / Number of non-volatile vector regs saved*
2371	// /*
2372	// / first register saved is assumed to be /
2373	// / 32 - vr_saved /
2374	// unsigned saves_vrsave:1; / Set if vrsave is saved on the stack /
2375	// unsigned has_varargs:1;
2376	// ...
2377	// };
2378	//
2379	// Here, the 7th bit is used as 'saves_vrsave'. To determine whether it
2380	// is 'struct vec_ext' or 'xtbtable' that follows 'alloca_reg',
2381	// we checks if the 7th bit is set or not because 'xtbtable' should
2382	// never have the 7th bit set. The 7th bit of 'xtbtable' will be reserved
2383	// in the future to make sure the mitigation works. This mitigation
2384	// is not 100% bullet proof because 'struct vec_ext' may not always have
2385	// 'saves_vrsave' bit set.
2386	//
2387	// 'reservedBit' is defined in enum 'xTBTableMask' above as the mask for
2388	// checking the 7th bit.
2389
2390	// p points to field name len.
2391	uint8_t charPtr = reinterpret_cast<uint8_t >(p);
2392
2393	// Skip fields name_len and name if they exist.
2394	if (TBTable->tb.name_present) {
2395	const uint16_t name_len = (reinterpret_cast<uint16_t >(charPtr));
2396	charPtr = charPtr + name_len + sizeof(uint16_t);
2397	}
2398
2399	// Skip field alloc_reg if it exists.
2400	if (TBTable->tb.uses_alloca)
2401	++charPtr;
2402
2403	// Check traceback table bit has_vec. Skip struct vec_ext if it exists.
2404	if (TBTable->tb.has_vec)
2405	// Note struct vec_ext does exist at this point because whether the
2406	// ordering of longtbtable and has_vec bits is correct or not, both
2407	// are set.
2408	charPtr += sizeof(struct vec_ext);
2409
2410	// charPtr points to field 'xtbtable'. Check if the EH info is available.
2411	// Also check if the reserved bit of the extended traceback table field
2412	// 'xtbtable' is set. If it is, the traceback table was incorrectly
2413	// generated by an XL compiler that uses the wrong ordering of 'longtbtable'
2414	// and 'has_vec' bits and this is in fact 'struct vec_ext'. So skip the
2415	// frame.
2416	if ((*charPtr & xTBTableMask::ehInfoBit) &&
2417	!(*charPtr & xTBTableMask::reservedBit)) {
2418	// Mark this frame has the new EH info.
2419	flags = frameType::frameWithEHInfo;
2420
2421	// eh_info is available.
2422	charPtr++;
2423	// The pointer is 4-byte aligned.
2424	if (reinterpret_cast<uintptr_t>(charPtr) % `4`)
2425	charPtr += `4` - reinterpret_cast<uintptr_t>(charPtr) % `4`;
2426	uintptr_t *ehInfo =
2427	reinterpret_cast<uintptr_t >((reinterpret_cast<uintptr_t *>(
2428	registers.getRegister(`2`) +
2429	(reinterpret_cast<uintptr_t >(charPtr)))));
2430
2431	// ehInfo points to structure en_info. The first member is version.
2432	// Only version 0 is currently supported.
2433	assert((reinterpret_cast<uint32_t >(ehInfo)) == `0` &&
2434	"libunwind: ehInfo version other than 0 is not supported");
2435
2436	// Increment ehInfo to point to member lsda.
2437	++ehInfo;
2438	lsda = *ehInfo++;
2439
2440	// enInfo now points to member personality.
2441	handler = *ehInfo;
2442
2443	_LIBUNWIND_TRACE_UNWINDING("Range table: LSDA=%#lx, Personality=%#lx\n",
2444	lsda, handler);
2445	}
2446	}
2447
2448	_info.start_ip = start_ip;
2449	_info.end_ip = end_ip;
2450	_info.lsda = lsda;
2451	_info.handler = handler;
2452	_info.gp = `0`;
2453	_info.flags = flags;
2454	_info.format = `0`;
2455	_info.unwind_info = reinterpret_cast<unw_word_t>(TBTable);
2456	_info.unwind_info_size = `0`;
2457	_info.extra = registers.getRegister(`2`);
2458
2459	return true;
2460	}
2461
2462	// Step back up the stack following the frame back link.
2463	template <typename A, typename R>
2464	int UnwindCursor<A, R>::stepWithTBTable(pint_t pc, tbtable *TBTable,
2465	R &registers, bool &isSignalFrame) {
2466	if (_LIBUNWIND_TRACING_UNWINDING) {
2467	char functionBuf[`512`];
2468	const char *functionName = functionBuf;
2469	unw_word_t offset;
2470	if (!getFunctionName(functionBuf, sizeof(functionBuf), &offset)) {
2471	functionName = ".anonymous.";
2472	}
2473	_LIBUNWIND_TRACE_UNWINDING(
2474	"%s: Look up traceback table of func=%s at %p, pc=%p, "
2475	"SP=%p, saves_lr=%d, stores_bc=%d",
2476	__func__, functionName, reinterpret_cast<void *>(TBTable),
2477	reinterpret_cast<void *>(pc),
2478	reinterpret_cast<void *>(registers.getSP()), TBTable->tb.saves_lr,
2479	TBTable->tb.stores_bc);
2480	}
2481
2482	#if defined(__powerpc64__)
2483	// Instruction to reload TOC register "ld r2,40(r1)"
2484	const uint32_t loadTOCRegInst = `0xe8410028`;
2485	const int32_t unwPPCF0Index = UNW_PPC64_F0;
2486	const int32_t unwPPCV0Index = UNW_PPC64_V0;
2487	#else
2488	// Instruction to reload TOC register "lwz r2,20(r1)"
2489	const uint32_t loadTOCRegInst = `0x80410014`;
2490	const int32_t unwPPCF0Index = UNW_PPC_F0;
2491	const int32_t unwPPCV0Index = UNW_PPC_V0;
2492	#endif
2493
2494	// lastStack points to the stack frame of the next routine up.
2495	pint_t curStack = static_cast<pint_t>(registers.getSP());
2496	pint_t lastStack = *reinterpret_cast<pint_t *>(curStack);
2497
2498	if (lastStack == `0`)
2499	return UNW_STEP_END;
2500
2501	R newRegisters = registers;
2502
2503	// If backchain is not stored, use the current stack frame.
2504	if (!TBTable->tb.stores_bc)
2505	lastStack = curStack;
2506
2507	// Return address is the address after call site instruction.
2508	pint_t returnAddress;
2509
2510	if (isSignalFrame) {
2511	_LIBUNWIND_TRACE_UNWINDING("Possible signal handler frame: lastStack=%p",
2512	reinterpret_cast<void *>(lastStack));
2513
2514	sigcontext sigContext = reinterpret_cast<sigcontext >(
2515	reinterpret_cast<char *>(lastStack) + STKMINALIGN);
2516	returnAddress = sigContext->sc_jmpbuf.jmp_context.iar;
2517
2518	bool useSTKMIN = false;
2519	if (returnAddress < `0x10000000`) {
2520	// Try again using STKMIN.
2521	sigContext = reinterpret_cast<sigcontext *>(
2522	reinterpret_cast<char *>(lastStack) + STKMIN);
2523	returnAddress = sigContext->sc_jmpbuf.jmp_context.iar;
2524	if (returnAddress < `0x10000000`) {
2525	_LIBUNWIND_TRACE_UNWINDING("Bad returnAddress=%p from sigcontext=%p",
2526	reinterpret_cast<void *>(returnAddress),
2527	reinterpret_cast<void *>(sigContext));
2528	return UNW_EBADFRAME;
2529	}
2530	useSTKMIN = true;
2531	}
2532	_LIBUNWIND_TRACE_UNWINDING("Returning from a signal handler %s: "
2533	"sigContext=%p, returnAddress=%p. "
2534	"Seems to be a valid address",
2535	useSTKMIN ? "STKMIN" : "STKMINALIGN",
2536	reinterpret_cast<void *>(sigContext),
2537	reinterpret_cast<void *>(returnAddress));
2538
2539	// Restore the condition register from sigcontext.
2540	newRegisters.setCR(sigContext->sc_jmpbuf.jmp_context.cr);
2541
2542	// Save the LR in sigcontext for stepping up when the function that
2543	// raised the signal is a leaf function. This LR has the return address
2544	// to the caller of the leaf function.
2545	newRegisters.setLR(sigContext->sc_jmpbuf.jmp_context.lr);
2546	_LIBUNWIND_TRACE_UNWINDING(
2547	"Save LR=%p from sigcontext",
2548	reinterpret_cast<void *>(sigContext->sc_jmpbuf.jmp_context.lr));
2549
2550	// Restore GPRs from sigcontext.
2551	for (int i = `0`; i < `32`; ++i)
2552	newRegisters.setRegister(i, sigContext->sc_jmpbuf.jmp_context.gpr[i]);
2553
2554	// Restore FPRs from sigcontext.
2555	for (int i = `0`; i < `32`; ++i)
2556	newRegisters.setFloatRegister(i + unwPPCF0Index,
2557	sigContext->sc_jmpbuf.jmp_context.fpr[i]);
2558
2559	// Restore vector registers if there is an associated extended context
2560	// structure.
2561	if (sigContext->sc_jmpbuf.jmp_context.msr & __EXTCTX) {
2562	ucontext_t uContext = reinterpret_cast<ucontext_t >(sigContext);
2563	if (uContext->__extctx->__extctx_magic == __EXTCTX_MAGIC) {
2564	for (int i = `0`; i < `32`; ++i)
2565	newRegisters.setVectorRegister(
2566	i + unwPPCV0Index, (reinterpret_cast<v128 >(
2567	&(uContext->__extctx->__vmx.__vr[i]))));
2568	}
2569	}
2570	} else {
2571	// Step up a normal frame.
2572
2573	if (!TBTable->tb.saves_lr && registers.getLR()) {
2574	// This case should only occur if we were called from a signal handler
2575	// and the signal occurred in a function that doesn't save the LR.
2576	returnAddress = static_cast<pint_t>(registers.getLR());
2577	_LIBUNWIND_TRACE_UNWINDING("Use saved LR=%p",
2578	reinterpret_cast<void *>(returnAddress));
2579	} else {
2580	// Otherwise, use the LR value in the stack link area.
2581	returnAddress = reinterpret_cast<pint_t *>(lastStack)[`2`];
2582	}
2583
2584	// Reset LR in the current context.
2585	newRegisters.setLR(static_cast<uintptr_t>(NULL));
2586
2587	_LIBUNWIND_TRACE_UNWINDING(
2588	"Extract info from lastStack=%p, returnAddress=%p",
2589	reinterpret_cast<void *>(lastStack),
2590	reinterpret_cast<void *>(returnAddress));
2591	_LIBUNWIND_TRACE_UNWINDING("fpr_regs=%d, gpr_regs=%d, saves_cr=%d",
2592	TBTable->tb.fpr_saved, TBTable->tb.gpr_saved,
2593	TBTable->tb.saves_cr);
2594
2595	// Restore FP registers.
2596	char ptrToRegs = reinterpret_cast<char* *>(lastStack);
2597	double FPRegs = reinterpret_cast<double* *>(
2598	ptrToRegs - (TBTable->tb.fpr_saved * sizeof(double)));
2599	for (int i = `0`; i < TBTable->tb.fpr_saved; ++i)
2600	newRegisters.setFloatRegister(
2601	`32` - TBTable->tb.fpr_saved + i + unwPPCF0Index, FPRegs[i]);
2602
2603	// Restore GP registers.
2604	ptrToRegs = reinterpret_cast<char *>(FPRegs);
2605	uintptr_t GPRegs = reinterpret_cast<uintptr_t >(
2606	ptrToRegs - (TBTable->tb.gpr_saved * sizeof(uintptr_t)));
2607	for (int i = `0`; i < TBTable->tb.gpr_saved; ++i)
2608	newRegisters.setRegister(`32` - TBTable->tb.gpr_saved + i, GPRegs[i]);
2609
2610	// Restore Vector registers.
2611	ptrToRegs = reinterpret_cast<char *>(GPRegs);
2612
2613	// Restore vector registers only if this is a Clang frame. Also
2614	// check if traceback table bit has_vec is set. If it is, structure
2615	// vec_ext is available.
2616	if (_info.flags == frameType::frameWithEHInfo && TBTable->tb.has_vec) {
2617
2618	// Get to the vec_ext structure to check if vector registers are saved.
2619	uint32_t p = reinterpret_cast<uint32_t >(&TBTable->tb_ext);
2620
2621	// Skip field parminfo if exists.
2622	if (TBTable->tb.fixedparms \|\| TBTable->tb.floatparms)
2623	++p;
2624
2625	// Skip field tb_offset if exists.
2626	if (TBTable->tb.has_tboff)
2627	++p;
2628
2629	// Skip field hand_mask if exists.
2630	if (TBTable->tb.int_hndl)
2631	++p;
2632
2633	// Skip fields ctl_info and ctl_info_disp if exist.
2634	if (TBTable->tb.has_ctl) {
2635	// Skip field ctl_info.
2636	++p;
2637	// Skip field ctl_info_disp.
2638	++p;
2639	}
2640
2641	// Skip fields name_len and name if exist.
2642	// p is supposed to point to field name_len now.
2643	uint8_t charPtr = reinterpret_cast<uint8_t >(p);
2644	if (TBTable->tb.name_present) {
2645	const uint16_t name_len = (reinterpret_cast<uint16_t >(charPtr));
2646	charPtr = charPtr + name_len + sizeof(uint16_t);
2647	}
2648
2649	// Skip field alloc_reg if it exists.
2650	if (TBTable->tb.uses_alloca)
2651	++charPtr;
2652
2653	struct vec_ext vec_ext = reinterpret_cast<struct* vec_ext *>(charPtr);
2654
2655	_LIBUNWIND_TRACE_UNWINDING("vr_saved=%d", vec_ext->vr_saved);
2656
2657	// Restore vector register(s) if saved on the stack.
2658	if (vec_ext->vr_saved) {
2659	// Saved vector registers are 16-byte aligned.
2660	if (reinterpret_cast<uintptr_t>(ptrToRegs) % `16`)
2661	ptrToRegs -= reinterpret_cast<uintptr_t>(ptrToRegs) % `16`;
2662	v128 VecRegs = reinterpret_cast<v128 >(ptrToRegs - vec_ext->vr_saved *
2663	sizeof(v128));
2664	for (int i = `0`; i < vec_ext->vr_saved; ++i) {
2665	newRegisters.setVectorRegister(
2666	`32` - vec_ext->vr_saved + i + unwPPCV0Index, VecRegs[i]);
2667	}
2668	}
2669	}
2670	if (TBTable->tb.saves_cr) {
2671	// Get the saved condition register. The condition register is only
2672	// a single word.
2673	newRegisters.setCR(
2674	(reinterpret_cast<uint32_t >(lastStack + sizeof(uintptr_t))));
2675	}
2676
2677	// Restore the SP.
2678	newRegisters.setSP(lastStack);
2679
2680	// The first instruction after return.
2681	uint32_t firstInstruction = (reinterpret_cast<uint32_t >(returnAddress));
2682
2683	// Do we need to set the TOC register?
2684	_LIBUNWIND_TRACE_UNWINDING(
2685	"Current gpr2=%p",
2686	reinterpret_cast<void *>(newRegisters.getRegister(`2`)));
2687	if (firstInstruction == loadTOCRegInst) {
2688	_LIBUNWIND_TRACE_UNWINDING(
2689	"Set gpr2=%p from frame",
2690	reinterpret_cast<void >(reinterpret_cast<pint_t >(lastStack)[`5`]));
2691	newRegisters.setRegister(`2`, reinterpret_cast<pint_t *>(lastStack)[`5`]);
2692	}
2693	}
2694	_LIBUNWIND_TRACE_UNWINDING("lastStack=%p, returnAddress=%p, pc=%p\n",
2695	reinterpret_cast<void *>(lastStack),
2696	reinterpret_cast<void *>(returnAddress),
2697	reinterpret_cast<void *>(pc));
2698
2699	// The return address is the address after call site instruction, so
2700	// setting IP to that simulates a return.
2701	newRegisters.setIP(reinterpret_cast<uintptr_t>(returnAddress));
2702
2703	// Simulate the step by replacing the register set with the new ones.
2704	registers = newRegisters;
2705
2706	// Check if the next frame is a signal frame.
2707	pint_t nextStack = (reinterpret_cast<pint_t >(registers.getSP()));
2708
2709	// Return address is the address after call site instruction.
2710	pint_t nextReturnAddress = reinterpret_cast<pint_t *>(nextStack)[`2`];
2711
2712	if (nextReturnAddress > `0x01` && nextReturnAddress < `0x10000`) {
2713	_LIBUNWIND_TRACE_UNWINDING("The next is a signal handler frame: "
2714	"nextStack=%p, next return address=%p\n",
2715	reinterpret_cast<void *>(nextStack),
2716	reinterpret_cast<void *>(nextReturnAddress));
2717	isSignalFrame = true;
2718	} else {
2719	isSignalFrame = false;
2720	}
2721	return UNW_STEP_SUCCESS;
2722	}
2723	#endif // defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
2724
2725	template <typename A, typename R>
2726	void UnwindCursor<A, R>::setInfoBasedOnIPRegister(bool isReturnAddress) {
2727	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) \|\| \
2728	defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
2729	_isSigReturn = false;
2730	#endif
2731
2732	typename R::reg_t rawPC = this->getReg(UNW_REG_IP);
2733
2734	#if defined(_LIBUNWIND_ARM_EHABI)
2735	// Remove the thumb bit so the IP represents the actual instruction address.
2736	// This matches the behaviour of _Unwind_GetIP on arm.
2737	rawPC &= (pint_t)~`0x1`;
2738	#endif
2739
2740	typename R::link_reg_t pc;
2741	#if defined(_LIBUNWIND_TARGET_AARCH64_AUTHENTICATED_UNWINDING)
2742	_registers.loadAndAuthenticateLinkRegister(rawPC, &pc);
2743	#else
2744	pc = rawPC;
2745	#endif
2746
2747	// Exit early if at the top of the stack.
2748	if (pc == `0`) {
2749	_unwindInfoMissing = true;
2750	return;
2751	}
2752
2753	// If the last line of a function is a "throw" the compiler sometimes
2754	// emits no instructions after the call to __cxa_throw. This means
2755	// the return address is actually the start of the next function.
2756	// To disambiguate this, back up the pc when we know it is a return
2757	// address.
2758	if (isReturnAddress)
2759	#if defined(_AIX)
2760	// PC needs to be a 4-byte aligned address to be able to look for a
2761	// word of 0 that indicates the start of the traceback table at the end
2762	// of a function on AIX.
2763	pc -= `4`;
2764	#else
2765	--pc;
2766	#endif
2767
2768	#if !(defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) && defined(_WIN32)) && \
2769	!defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
2770	// In case of this is frame of signal handler, the IP saved in the signal
2771	// handler points to first non-executed instruction, while FDE/CIE expects IP
2772	// to be after the first non-executed instruction.
2773	if (_isSignalFrame)
2774	++pc;
2775	#endif
2776
2777	// Ask address space object to find unwind sections for this pc.
2778	UnwindInfoSections sects;
2779	if (_addressSpace.template findUnwindSections<R>(pc, sects)) {
2780	#if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
2781	// If there is a compact unwind encoding table, look there first.
2782	if (sects.compact_unwind_section != `0`) {
2783	if (this->getInfoFromCompactEncodingSection(pc, sects)) {
2784	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
2785	// Found info in table, done unless encoding says to use dwarf.
2786	uint32_t dwarfOffset;
2787	if ((sects.dwarf_section != `0`) && compactSaysUseDwarf(&dwarfOffset)) {
2788	if (this->getInfoFromDwarfSection(pc, sects, dwarfOffset)) {
2789	// found info in dwarf, done
2790	return;
2791	}
2792	}
2793	#endif
2794	// If unwind table has entry, but entry says there is no unwind info,
2795	// record that we have no unwind info.
2796	if (_info.format == `0`)
2797	_unwindInfoMissing = true;
2798	return;
2799	}
2800	}
2801	#endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
2802
2803	#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
2804	// If there is SEH unwind info, look there next.
2805	if (this->getInfoFromSEH(pc))
2806	return;
2807	#endif
2808
2809	#if defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
2810	// If there is unwind info in the traceback table, look there next.
2811	if (this->getInfoFromTBTable(pc, _registers))
2812	return;
2813	#endif
2814
2815	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
2816	// If there is dwarf unwind info, look there next.
2817	if (sects.dwarf_section != `0`) {
2818	if (this->getInfoFromDwarfSection(pc, sects)) {
2819	// found info in dwarf, done
2820	return;
2821	}
2822	}
2823	#endif
2824
2825	#if defined(_LIBUNWIND_ARM_EHABI)
2826	// If there is ARM EHABI unwind info, look there next.
2827	if (sects.arm_section != `0` && this->getInfoFromEHABISection(pc, sects))
2828	return;
2829	#endif
2830	}
2831
2832	#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
2833	// There is no static unwind info for this pc. Look to see if an FDE was
2834	// dynamically registered for it.
2835	pint_t cachedFDE =
2836	DwarfFDECache<A>::template findFDE<R>(DwarfFDECache<A>::kSearchAll, pc);
2837	if (cachedFDE != `0`) {
2838	typename CFI_Parser<A>::FDE_Info fdeInfo;
2839	typename CFI_Parser<A>::CIE_Info cieInfo;
2840	if (!CFI_Parser<A>::decodeFDE(_addressSpace, cachedFDE, &fdeInfo, &cieInfo))
2841	if (getInfoFromFdeCie(fdeInfo, cieInfo, pc, dso_base: `0`))
2842	return;
2843	}
2844
2845	// Lastly, ask AddressSpace object about platform specific ways to locate
2846	// other FDEs.
2847	pint_t fde;
2848	if (_addressSpace.template findOtherFDE<R>(pc, fde)) {
2849	typename CFI_Parser<A>::FDE_Info fdeInfo;
2850	typename CFI_Parser<A>::CIE_Info cieInfo;
2851	if (!CFI_Parser<A>::decodeFDE(_addressSpace, fde, &fdeInfo, &cieInfo)) {
2852	// Double check this FDE is for a function that includes the pc.
2853	if ((fdeInfo.pcStart <= pc) && (pc < fdeInfo.pcEnd))
2854	if (getInfoFromFdeCie(fdeInfo, cieInfo, pc, dso_base: `0`))
2855	return;
2856	}
2857	}
2858	#endif // #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
2859
2860	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) \|\| \
2861	defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
2862	if (setInfoForSigReturn())
2863	return;
2864	#endif
2865
2866	// no unwind info, flag that we can't reliably unwind
2867	_unwindInfoMissing = true;
2868	}
2869
2870	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) && \
2871	defined(_LIBUNWIND_TARGET_AARCH64)
2872
2873	/*
2874	* The linux sigreturn restorer stub will always have the form:
2875	*
2876	* d2801168 movz x8, #0x8b
2877	* d4000001 svc #0x0
2878	*/
2879	#if defined(__AARCH64EB__)
2880	#define MOVZ_X8_8B 0x681180d2
2881	#define SVC_0 0x010000d4
2882	#else
2883	#define MOVZ_X8_8B 0xd2801168
2884	#define SVC_0 0xd4000001
2885	#endif
2886
2887	template <typename A, typename R>
2888	bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_arm64 &) {
2889	// Look for the sigreturn trampoline. The trampoline's body is two
2890	// specific instructions (see below). Typically the trampoline comes from the
2891	// vDSO[1] (i.e. the __kernel_rt_sigreturn function). A libc might provide its
2892	// own restorer function, though, or user-mode QEMU might write a trampoline
2893	// onto the stack.
2894	//
2895	// This special code path is a fallback that is only used if the trampoline
2896	// lacks proper (e.g. DWARF) unwind info. On AArch64, a new DWARF register
2897	// constant for the PC needs to be defined before DWARF can handle a signal
2898	// trampoline. This code may segfault if the target PC is unreadable, e.g.:
2899	// - The PC points at a function compiled without unwind info, and which is
2900	// part of an execute-only mapping (e.g. using -Wl,--execute-only).
2901	// - The PC is invalid and happens to point to unreadable or unmapped memory.
2902	//
2903	// [1] https://github.com/torvalds/linux/blob/master/arch/arm64/kernel/vdso/sigreturn.S
2904	const pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
2905	// The PC might contain an invalid address if the unwind info is bad, so
2906	// directly accessing it could cause a SIGSEGV.
2907	if (!isReadableAddr(pc))
2908	return false;
2909	auto instructions = reinterpret_cast<const* uint32_t *>(pc);
2910	// Look for instructions: mov x8, #0x8b; svc #0x0
2911	if (instructions[`0`] != MOVZ_X8_8B \|\| instructions[`1`] != SVC_0)
2912	return false;
2913
2914	_info = {};
2915	_info.start_ip = pc;
2916	_info.end_ip = pc + `4`;
2917	_isSigReturn = true;
2918	return true;
2919	}
2920
2921	template <typename A, typename R>
2922	int UnwindCursor<A, R>::stepThroughSigReturn(Registers_arm64 &) {
2923	// In the signal trampoline frame, sp points to an rt_sigframe[1], which is:
2924	// - 128-byte siginfo struct
2925	// - ucontext struct:
2926	// - 8-byte long (uc_flags)
2927	// - 8-byte pointer (uc_link)
2928	// - 24-byte stack_t
2929	// - 128-byte signal set
2930	// - 8 bytes of padding because sigcontext has 16-byte alignment
2931	// - sigcontext/mcontext_t
2932	// [1] https://github.com/torvalds/linux/blob/master/arch/arm64/kernel/signal.c
2933	const pint_t kOffsetSpToSigcontext = (`128` + `8` + `8` + `24` + `128` + `8`); // 304
2934
2935	// Offsets from sigcontext to each register.
2936	const pint_t kOffsetGprs = `8`; // offset to "__u64 regs[31]" field
2937	const pint_t kOffsetSp = `256`; // offset to "__u64 sp" field
2938	const pint_t kOffsetPc = `264`; // offset to "__u64 pc" field
2939
2940	pint_t sigctx = _registers.getSP() + kOffsetSpToSigcontext;
2941
2942	for (int i = `0`; i <= `30`; ++i) {
2943	uint64_t value = _addressSpace.get64(sigctx + kOffsetGprs +
2944	static_cast<pint_t>(i * `8`));
2945	_registers.setRegister(UNW_AARCH64_X0 + i, value);
2946	}
2947	_registers.setSP(_addressSpace.get64(sigctx + kOffsetSp));
2948	_registers.setIP(_addressSpace.get64(sigctx + kOffsetPc));
2949	_isSignalFrame = true;
2950	return UNW_STEP_SUCCESS;
2951	}
2952	#endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&
2953	// defined(_LIBUNWIND_TARGET_AARCH64)
2954
2955	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) && \
2956	defined(_LIBUNWIND_TARGET_LOONGARCH)
2957	template <typename A, typename R>
2958	bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_loongarch &) {
2959	const pint_t pc = static_cast<pint_t>(getReg(UNW_REG_IP));
2960	// The PC might contain an invalid address if the unwind info is bad, so
2961	// directly accessing it could cause a SIGSEGV.
2962	if (!isReadableAddr(pc))
2963	return false;
2964	const auto instructions = reinterpret_cast<const* uint32_t *>(pc);
2965	// Look for the two instructions used in the sigreturn trampoline
2966	// __vdso_rt_sigreturn:
2967	//
2968	// 0x03822c0b li a7,0x8b
2969	// 0x002b0000 syscall 0
2970	if (instructions[`0`] != `0x03822c0b` \|\| instructions[`1`] != `0x002b0000`)
2971	return false;
2972
2973	_info = {};
2974	_info.start_ip = pc;
2975	_info.end_ip = pc + `4`;
2976	_isSigReturn = true;
2977	return true;
2978	}
2979
2980	template <typename A, typename R>
2981	int UnwindCursor<A, R>::stepThroughSigReturn(Registers_loongarch &) {
2982	// In the signal trampoline frame, sp points to an rt_sigframe[1], which is:
2983	// - 128-byte siginfo struct
2984	// - ucontext_t struct:
2985	// - 8-byte long (__uc_flags)
2986	// - 8-byte pointer (uc_link)*
2987	// - 24-byte uc_stack
2988	// - 8-byte uc_sigmask
2989	// - 120-byte of padding to allow sigset_t to be expanded in the future
2990	// - 8 bytes of padding because sigcontext has 16-byte alignment
2991	// - struct sigcontext uc_mcontext
2992	// [1]
2993	// https://github.com/torvalds/linux/blob/master/arch/loongarch/kernel/signal.c
2994	const pint_t kOffsetSpToSigcontext = `128` + `8` + `8` + `24` + `8` + `128`;
2995
2996	const pint_t sigctx = _registers.getSP() + kOffsetSpToSigcontext;
2997	_registers.setIP(_addressSpace.get64(sigctx));
2998	for (int i = UNW_LOONGARCH_R1; i <= UNW_LOONGARCH_R31; ++i) {
2999	// skip R0
3000	uint64_t value =
3001	_addressSpace.get64(sigctx + static_cast<pint_t>((i + `1`) * `8`));
3002	_registers.setRegister(i, value);
3003	}
3004	_isSignalFrame = true;
3005	return UNW_STEP_SUCCESS;
3006	}
3007	#endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&
3008	// defined(_LIBUNWIND_TARGET_LOONGARCH)
3009
3010	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) && \
3011	defined(_LIBUNWIND_TARGET_RISCV)
3012	template <typename A, typename R>
3013	bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_riscv &) {
3014	const pint_t pc = static_cast<pint_t>(getReg(UNW_REG_IP));
3015	// The PC might contain an invalid address if the unwind info is bad, so
3016	// directly accessing it could cause a SIGSEGV.
3017	if (!isReadableAddr(pc))
3018	return false;
3019	const auto instructions = reinterpret_cast<const* uint32_t *>(pc);
3020	// Look for the two instructions used in the sigreturn trampoline
3021	// __vdso_rt_sigreturn:
3022	//
3023	// 0x08b00893 li a7,0x8b
3024	// 0x00000073 ecall
3025	if (instructions[`0`] != `0x08b00893` \|\| instructions[`1`] != `0x00000073`)
3026	return false;
3027
3028	_info = {};
3029	_info.start_ip = pc;
3030	_info.end_ip = pc + `4`;
3031	_isSigReturn = true;
3032	return true;
3033	}
3034
3035	template <typename A, typename R>
3036	int UnwindCursor<A, R>::stepThroughSigReturn(Registers_riscv &) {
3037	// In the signal trampoline frame, sp points to an rt_sigframe[1], which is:
3038	// - 128-byte siginfo struct
3039	// - ucontext_t struct:
3040	// - 8-byte long (__uc_flags)
3041	// - 8-byte pointer (uc_link)*
3042	// - 24-byte uc_stack
3043	// - 8-byte uc_sigmask
3044	// - 120-byte of padding to allow sigset_t to be expanded in the future
3045	// - 8 bytes of padding because sigcontext has 16-byte alignment
3046	// - struct sigcontext uc_mcontext
3047	// [1]
3048	// https://github.com/torvalds/linux/blob/master/arch/riscv/kernel/signal.c
3049	const pint_t kOffsetSpToSigcontext = `128` + `8` + `8` + `24` + `8` + `128`;
3050
3051	const pint_t sigctx = _registers.getSP() + kOffsetSpToSigcontext;
3052	_registers.setIP(_addressSpace.get64(sigctx));
3053	for (int i = UNW_RISCV_X1; i <= UNW_RISCV_X31; ++i) {
3054	uint64_t value = _addressSpace.get64(sigctx + static_cast<pint_t>(i * `8`));
3055	_registers.setRegister(i, value);
3056	}
3057	_isSignalFrame = true;
3058	return UNW_STEP_SUCCESS;
3059	}
3060	#endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&
3061	// defined(_LIBUNWIND_TARGET_RISCV)
3062
3063	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) && \
3064	defined(_LIBUNWIND_TARGET_S390X)
3065	template <typename A, typename R>
3066	bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_s390x &) {
3067	// Look for the sigreturn trampoline. The trampoline's body is a
3068	// specific instruction (see below). Typically the trampoline comes from the
3069	// vDSO (i.e. the __kernel_[rt_]sigreturn function). A libc might provide its
3070	// own restorer function, though, or user-mode QEMU might write a trampoline
3071	// onto the stack.
3072	const pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
3073	// The PC might contain an invalid address if the unwind info is bad, so
3074	// directly accessing it could cause a SIGSEGV.
3075	if (!isReadableAddr(pc))
3076	return false;
3077	const auto inst = *reinterpret_cast<const uint16_t *>(pc);
3078	if (inst == `0x0a77` \|\| inst == `0x0aad`) {
3079	_info = {};
3080	_info.start_ip = pc;
3081	_info.end_ip = pc + `2`;
3082	_isSigReturn = true;
3083	return true;
3084	}
3085	return false;
3086	}
3087
3088	template <typename A, typename R>
3089	int UnwindCursor<A, R>::stepThroughSigReturn(Registers_s390x &) {
3090	// Determine current SP.
3091	const pint_t sp = static_cast<pint_t>(this->getReg(UNW_REG_SP));
3092	// According to the s390x ABI, the CFA is at (incoming) SP + 160.
3093	const pint_t cfa = sp + `160`;
3094
3095	// Determine current PC and instruction there (this must be either
3096	// a "svc __NR_sigreturn" or "svc __NR_rt_sigreturn").
3097	const pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
3098	const uint16_t inst = _addressSpace.get16(pc);
3099
3100	// Find the addresses of the signo and sigcontext in the frame.
3101	pint_t pSigctx = `0`;
3102	pint_t pSigno = `0`;
3103
3104	// "svc __NR_sigreturn" uses a non-RT signal trampoline frame.
3105	if (inst == `0x0a77`) {
3106	// Layout of a non-RT signal trampoline frame, starting at the CFA:
3107	// - 8-byte signal mask
3108	// - 8-byte pointer to sigcontext, followed by signo
3109	// - 4-byte signo
3110	pSigctx = _addressSpace.get64(cfa + `8`);
3111	pSigno = pSigctx + `344`;
3112	}
3113
3114	// "svc __NR_rt_sigreturn" uses a RT signal trampoline frame.
3115	if (inst == `0x0aad`) {
3116	// Layout of a RT signal trampoline frame, starting at the CFA:
3117	// - 8-byte retcode (+ alignment)
3118	// - 128-byte siginfo struct (starts with signo)
3119	// - ucontext struct:
3120	// - 8-byte long (uc_flags)
3121	// - 8-byte pointer (uc_link)
3122	// - 24-byte stack_t
3123	// - 8 bytes of padding because sigcontext has 16-byte alignment
3124	// - sigcontext/mcontext_t
3125	pSigctx = cfa + `8` + `128` + `8` + `8` + `24` + `8`;
3126	pSigno = cfa + `8`;
3127	}
3128
3129	assert(pSigctx != `0`);
3130	assert(pSigno != `0`);
3131
3132	// Offsets from sigcontext to each register.
3133	const pint_t kOffsetPc = `8`;
3134	const pint_t kOffsetGprs = `16`;
3135	const pint_t kOffsetFprs = `216`;
3136
3137	// Restore all registers.
3138	for (int i = `0`; i < `16`; ++i) {
3139	uint64_t value = _addressSpace.get64(pSigctx + kOffsetGprs +
3140	static_cast<pint_t>(i * `8`));
3141	_registers.setRegister(UNW_S390X_R0 + i, value);
3142	}
3143	for (int i = `0`; i < `16`; ++i) {
3144	static const int fpr[`16`] = {
3145	UNW_S390X_F0, UNW_S390X_F1, UNW_S390X_F2, UNW_S390X_F3,
3146	UNW_S390X_F4, UNW_S390X_F5, UNW_S390X_F6, UNW_S390X_F7,
3147	UNW_S390X_F8, UNW_S390X_F9, UNW_S390X_F10, UNW_S390X_F11,
3148	UNW_S390X_F12, UNW_S390X_F13, UNW_S390X_F14, UNW_S390X_F15
3149	};
3150	double value = _addressSpace.getDouble(pSigctx + kOffsetFprs +
3151	static_cast<pint_t>(i * `8`));
3152	_registers.setFloatRegister(fpr[i], value);
3153	}
3154	_registers.setIP(_addressSpace.get64(pSigctx + kOffsetPc));
3155
3156	// SIGILL, SIGFPE and SIGTRAP are delivered with psw_addr
3157	// after the faulting instruction rather than before it.
3158	// Do not set _isSignalFrame in that case.
3159	uint32_t signo = _addressSpace.get32(pSigno);
3160	_isSignalFrame = (signo != `4` && signo != `5` && signo != `8`);
3161
3162	return UNW_STEP_SUCCESS;
3163	}
3164	#endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&
3165	// defined(_LIBUNWIND_TARGET_S390X)
3166
3167	#if defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
3168	template <typename A, typename R>
3169	bool UnwindCursor<A, R>::setInfoForSigReturn() {
3170	Dl_info dlinfo;
3171	const auto isSignalHandler = [&](pint_t addr) {
3172	if (!dladdr(reinterpret_cast<void *>(addr), &dlinfo))
3173	return false;
3174	if (strcmp(dlinfo.dli_fname, "commpage"))
3175	return false;
3176	if (dlinfo.dli_sname == NULL \|\|
3177	strcmp(dlinfo.dli_sname, "commpage_signal_handler"))
3178	return false;
3179	return true;
3180	};
3181
3182	pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
3183	if (!isSignalHandler(pc))
3184	return false;
3185
3186	pint_t start = reinterpret_cast<pint_t>(dlinfo.dli_saddr);
3187
3188	static size_t signalHandlerSize = `0`;
3189	if (signalHandlerSize == `0`) {
3190	size_t boundLow = `0`;
3191	size_t boundHigh = static_cast<size_t>(-`1`);
3192
3193	area_info areaInfo;
3194	if (get_area_info(area_for(dlinfo.dli_saddr), &areaInfo) == B_OK)
3195	boundHigh = areaInfo.size;
3196
3197	while (boundLow < boundHigh) {
3198	size_t boundMid = boundLow + ((boundHigh - boundLow) / `2`);
3199	pint_t test = start + boundMid;
3200	if (test >= start && isSignalHandler(test))
3201	boundLow = boundMid + `1`;
3202	else
3203	boundHigh = boundMid;
3204	}
3205
3206	signalHandlerSize = boundHigh;
3207	}
3208
3209	_info = {};
3210	_info.start_ip = start;
3211	_info.end_ip = start + signalHandlerSize;
3212	_isSigReturn = true;
3213
3214	return true;
3215	}
3216
3217	template <typename A, typename R>
3218	int UnwindCursor<A, R>::stepThroughSigReturn() {
3219	_isSignalFrame = true;
3220
3221	#if defined(_LIBUNWIND_TARGET_X86_64)
3222	// Layout of the stack before function call:
3223	// - signal_frame_data
3224	// + siginfo_t (public struct, fairly stable)
3225	// + ucontext_t (public struct, fairly stable)
3226	// - mcontext_t -> Offset 0x70, this is what we want.
3227	// - frame->ip (8 bytes)
3228	// - frame->bp (8 bytes). Not written by the kernel,
3229	// but the signal handler has a "push %rbp" instruction.
3230	pint_t bp = this->getReg(UNW_X86_64_RBP);
3231	vregs regs = (vregs )(bp + `0x70`);
3232
3233	_registers.setRegister(UNW_REG_IP, regs->rip);
3234	_registers.setRegister(UNW_REG_SP, regs->rsp);
3235	_registers.setRegister(UNW_X86_64_RAX, regs->rax);
3236	_registers.setRegister(UNW_X86_64_RDX, regs->rdx);
3237	_registers.setRegister(UNW_X86_64_RCX, regs->rcx);
3238	_registers.setRegister(UNW_X86_64_RBX, regs->rbx);
3239	_registers.setRegister(UNW_X86_64_RSI, regs->rsi);
3240	_registers.setRegister(UNW_X86_64_RDI, regs->rdi);
3241	_registers.setRegister(UNW_X86_64_RBP, regs->rbp);
3242	_registers.setRegister(UNW_X86_64_R8, regs->r8);
3243	_registers.setRegister(UNW_X86_64_R9, regs->r9);
3244	_registers.setRegister(UNW_X86_64_R10, regs->r10);
3245	_registers.setRegister(UNW_X86_64_R11, regs->r11);
3246	_registers.setRegister(UNW_X86_64_R12, regs->r12);
3247	_registers.setRegister(UNW_X86_64_R13, regs->r13);
3248	_registers.setRegister(UNW_X86_64_R14, regs->r14);
3249	_registers.setRegister(UNW_X86_64_R15, regs->r15);
3250	// TODO: XMM
3251	#endif // defined(_LIBUNWIND_TARGET_X86_64)
3252
3253	return UNW_STEP_SUCCESS;
3254	}
3255	#endif // defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
3256
3257	template <typename A, typename R> int UnwindCursor<A, R>::step(bool stage2) {
3258	(void)stage2;
3259	// Bottom of stack is defined when unwind info cannot be found.
3260	if (_unwindInfoMissing)
3261	return UNW_STEP_END;
3262
3263	// Use unwinding info to modify register set as if function returned.
3264	int result;
3265	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) \|\| \
3266	defined(_LIBUNWIND_CHECK_HAIKU_SIGRETURN)
3267	if (_isSigReturn) {
3268	result = this->stepThroughSigReturn();
3269	} else
3270	#endif
3271	{
3272	#if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
3273	result = this->stepWithCompactEncoding(stage2);
3274	#elif defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
3275	result = this->stepWithSEHData();
3276	#elif defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
3277	result = this->stepWithTBTableData();
3278	#elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
3279	result = this->stepWithDwarfFDE(stage2);
3280	#elif defined(_LIBUNWIND_ARM_EHABI)
3281	result = this->stepWithEHABI();
3282	#else
3283	#error Need _LIBUNWIND_SUPPORT_COMPACT_UNWIND or \
3284	_LIBUNWIND_SUPPORT_SEH_UNWIND or \
3285	_LIBUNWIND_SUPPORT_DWARF_UNWIND or \
3286	_LIBUNWIND_ARM_EHABI
3287	#endif
3288	}
3289
3290	// update info based on new PC
3291	if (result == UNW_STEP_SUCCESS) {
3292	this->setInfoBasedOnIPRegister(true);
3293	if (_unwindInfoMissing)
3294	return UNW_STEP_END;
3295	}
3296
3297	return result;
3298	}
3299
3300	template <typename A, typename R>
3301	void UnwindCursor<A, R>::getInfo(unw_proc_info_t *info) {
3302	if (_unwindInfoMissing)
3303	memset(s: static_cast<void >(info), c: `0`, n: sizeof(info));
3304	else
3305	*info = _info;
3306	}
3307
3308	template <typename A, typename R>
3309	bool UnwindCursor<A, R>::getFunctionName(char *buf, size_t bufLen,
3310	unw_word_t *offset) {
3311	#if defined(_LIBUNWIND_TARGET_AARCH64_AUTHENTICATED_UNWINDING)
3312	typename R::reg_t rawPC = this->getReg(UNW_REG_IP);
3313	typename R::link_reg_t pc;
3314	_registers.loadAndAuthenticateLinkRegister(rawPC, &pc);
3315	#else
3316	typename R::link_reg_t pc = this->getReg(UNW_REG_IP);
3317	#endif
3318	return _addressSpace.template findFunctionName<R>(pc, buf, bufLen, offset);
3319	}
3320
3321	#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN)
3322	template <typename A, typename R>
3323	bool UnwindCursor<A, R>::isReadableAddr(const pint_t addr) const {
3324	// We use SYS_rt_sigprocmask, inspired by Abseil's AddressIsReadable.
3325
3326	const auto sigsetAddr = reinterpret_cast<sigset_t *>(addr);
3327	// We have to check that addr is nullptr because sigprocmask allows that
3328	// as an argument without failure.
3329	if (!sigsetAddr)
3330	return false;
3331	const auto saveErrno = errno;
3332	// We MUST use a raw syscall here, as wrappers may try to access
3333	// sigsetAddr which may cause a SIGSEGV. A raw syscall however is
3334	// safe. Additionally, we need to pass the kernel_sigset_size, which is
3335	// different from libc sizeof(sigset_t). For the majority of architectures,
3336	// it's 64 bits (_NSIG), and libc NSIG is _NSIG + 1.
3337	const auto kernelSigsetSize = NSIG / `8`;
3338	[[maybe_unused]] const int Result = syscall(
3339	SYS_rt_sigprocmask, /how=/~`0`, sigsetAddr, nullptr, kernelSigsetSize);
3340	// Because our "how" is invalid, this syscall should always fail, and our
3341	// errno should always be EINVAL or an EFAULT. This relies on the Linux
3342	// kernel to check copy_from_user before checking if the "how" argument is
3343	// invalid.
3344	assert(Result == -`1`);
3345	assert(errno == EFAULT \|\| errno == EINVAL);
3346	const auto readable = errno != EFAULT;
3347	errno = saveErrno;
3348	return readable;
3349	}
3350	#endif
3351
3352	#if defined(_LIBUNWIND_USE_CET) \|\| defined(_LIBUNWIND_USE_GCS)
3353	extern "C" void __libunwind_shstk_get_registers(unw_cursor_t cursor) {
3354	AbstractUnwindCursor co = (AbstractUnwindCursor )cursor;
3355	return co->get_registers();
3356	}
3357	#endif
3358	} // namespace libunwind
3359
3360	#endif // __UNWINDCURSOR_HPP__
3361

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