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