1 //===------------------------- UnwindCursor.hpp ---------------------------===//
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 <stdint.h>
15 #include <stdio.h>
16 #include <stdlib.h>
17 #include <unwind.h>
18 
19 #ifdef _WIN32
20   #include <windows.h>
21   #include <ntverp.h>
22 #endif
23 #ifdef __APPLE__
24   #include <mach-o/dyld.h>
25 #endif
26 
27 #if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
28 // Provide a definition for the DISPATCHER_CONTEXT struct for old (Win7 and
29 // earlier) SDKs.
30 // MinGW-w64 has always provided this struct.
31   #if defined(_WIN32) && defined(_LIBUNWIND_TARGET_X86_64) && \
32       !defined(__MINGW32__) && VER_PRODUCTBUILD < 8000
33 struct _DISPATCHER_CONTEXT {
34   ULONG64 ControlPc;
35   ULONG64 ImageBase;
36   PRUNTIME_FUNCTION FunctionEntry;
37   ULONG64 EstablisherFrame;
38   ULONG64 TargetIp;
39   PCONTEXT ContextRecord;
40   PEXCEPTION_ROUTINE LanguageHandler;
41   PVOID HandlerData;
42   PUNWIND_HISTORY_TABLE HistoryTable;
43   ULONG ScopeIndex;
44   ULONG Fill0;
45 };
46   #endif
47 
48 struct UNWIND_INFO {
49   uint8_t Version : 3;
50   uint8_t Flags : 5;
51   uint8_t SizeOfProlog;
52   uint8_t CountOfCodes;
53   uint8_t FrameRegister : 4;
54   uint8_t FrameOffset : 4;
55   uint16_t UnwindCodes[2];
56 };
57 
58 extern "C" _Unwind_Reason_Code __libunwind_seh_personality(
59     int, _Unwind_Action, uint64_t, _Unwind_Exception *,
60     struct _Unwind_Context *);
61 
62 #endif
63 
64 #include "config.h"
65 
66 #include "AddressSpace.hpp"
67 #include "CompactUnwinder.hpp"
68 #include "config.h"
69 #include "DwarfInstructions.hpp"
70 #include "EHHeaderParser.hpp"
71 #include "libunwind.h"
72 #include "Registers.hpp"
73 #include "RWMutex.hpp"
74 #include "Unwind-EHABI.h"
75 
76 namespace libunwind {
77 
78 static thread_local UnwindInfoSectionsCache uwis_cache;
79 
80 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
81 /// Cache of recently found FDEs.
82 template <typename A>
83 class _LIBUNWIND_HIDDEN DwarfFDECache {
84   typedef typename A::pint_t pint_t;
85 public:
86   static constexpr pint_t kSearchAll = static_cast<pint_t>(-1);
87   static pint_t findFDE(pint_t mh, pint_t pc);
88   static void add(pint_t mh, pint_t ip_start, pint_t ip_end, pint_t fde);
89   static void removeAllIn(pint_t mh);
90   static void iterateCacheEntries(void (*func)(unw_word_t ip_start,
91                                                unw_word_t ip_end,
92                                                unw_word_t fde, unw_word_t mh));
93 
94 private:
95 
96   struct entry {
97     pint_t mh;
98     pint_t ip_start;
99     pint_t ip_end;
100     pint_t fde;
101   };
102 
103   // These fields are all static to avoid needing an initializer.
104   // There is only one instance of this class per process.
105   static RWMutex _lock;
106 #ifdef __APPLE__
107   static void dyldUnloadHook(const struct mach_header *mh, intptr_t slide);
108   static bool _registeredForDyldUnloads;
109 #endif
110   static entry *_buffer;
111   static entry *_bufferUsed;
112   static entry *_bufferEnd;
113   static entry _initialBuffer[64];
114 };
115 
116 template <typename A>
117 typename DwarfFDECache<A>::entry *
118 DwarfFDECache<A>::_buffer = _initialBuffer;
119 
120 template <typename A>
121 typename DwarfFDECache<A>::entry *
122 DwarfFDECache<A>::_bufferUsed = _initialBuffer;
123 
124 template <typename A>
125 typename DwarfFDECache<A>::entry *
126 DwarfFDECache<A>::_bufferEnd = &_initialBuffer[64];
127 
128 template <typename A>
129 typename DwarfFDECache<A>::entry DwarfFDECache<A>::_initialBuffer[64];
130 
131 template <typename A>
132 RWMutex DwarfFDECache<A>::_lock;
133 
134 #ifdef __APPLE__
135 template <typename A>
136 bool DwarfFDECache<A>::_registeredForDyldUnloads = false;
137 #endif
138 
139 template <typename A>
140 typename A::pint_t DwarfFDECache<A>::findFDE(pint_t mh, pint_t pc) {
141   pint_t result = 0;
142   _LIBUNWIND_LOG_IF_FALSE(_lock.lock_shared());
143   for (entry *p = _buffer; p < _bufferUsed; ++p) {
144     if ((mh == p->mh) || (mh == kSearchAll)) {
145       if ((p->ip_start <= pc) && (pc < p->ip_end)) {
146         result = p->fde;
147         break;
148       }
149     }
150   }
151   _LIBUNWIND_LOG_IF_FALSE(_lock.unlock_shared());
152   return result;
153 }
154 
155 template <typename A>
156 void DwarfFDECache<A>::add(pint_t mh, pint_t ip_start, pint_t ip_end,
157                            pint_t fde) {
158 #if !defined(_LIBUNWIND_NO_HEAP)
159   _LIBUNWIND_LOG_IF_FALSE(_lock.lock());
160   if (_bufferUsed >= _bufferEnd) {
161     size_t oldSize = (size_t)(_bufferEnd - _buffer);
162     size_t newSize = oldSize * 4;
163     // Can't use operator new (we are below it).
164     entry *newBuffer = (entry *)malloc(newSize * sizeof(entry));
165     memcpy(newBuffer, _buffer, oldSize * sizeof(entry));
166     if (_buffer != _initialBuffer)
167       free(_buffer);
168     _buffer = newBuffer;
169     _bufferUsed = &newBuffer[oldSize];
170     _bufferEnd = &newBuffer[newSize];
171   }
172   _bufferUsed->mh = mh;
173   _bufferUsed->ip_start = ip_start;
174   _bufferUsed->ip_end = ip_end;
175   _bufferUsed->fde = fde;
176   ++_bufferUsed;
177 #ifdef __APPLE__
178   if (!_registeredForDyldUnloads) {
179     _dyld_register_func_for_remove_image(&dyldUnloadHook);
180     _registeredForDyldUnloads = true;
181   }
182 #endif
183   _LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
184 #endif
185 }
186 
187 template <typename A>
188 void DwarfFDECache<A>::removeAllIn(pint_t mh) {
189   _LIBUNWIND_LOG_IF_FALSE(_lock.lock());
190   entry *d = _buffer;
191   for (const entry *s = _buffer; s < _bufferUsed; ++s) {
192     if (s->mh != mh) {
193       if (d != s)
194         *d = *s;
195       ++d;
196     }
197   }
198   _bufferUsed = d;
199   _LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
200 }
201 
202 #ifdef __APPLE__
203 template <typename A>
204 void DwarfFDECache<A>::dyldUnloadHook(const struct mach_header *mh, intptr_t ) {
205   removeAllIn((pint_t) mh);
206 }
207 #endif
208 
209 template <typename A>
210 void DwarfFDECache<A>::iterateCacheEntries(void (*func)(
211     unw_word_t ip_start, unw_word_t ip_end, unw_word_t fde, unw_word_t mh)) {
212   _LIBUNWIND_LOG_IF_FALSE(_lock.lock());
213   for (entry *p = _buffer; p < _bufferUsed; ++p) {
214     (*func)(p->ip_start, p->ip_end, p->fde, p->mh);
215   }
216   _LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
217 }
218 #endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
219 
220 
221 #define arrayoffsetof(type, index, field) ((size_t)(&((type *)0)[index].field))
222 
223 #if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
224 template <typename A> class UnwindSectionHeader {
225 public:
226   UnwindSectionHeader(A &addressSpace, typename A::pint_t addr)
227       : _addressSpace(addressSpace), _addr(addr) {}
228 
229   uint32_t version() const {
230     return _addressSpace.get32(_addr +
231                                offsetof(unwind_info_section_header, version));
232   }
233   uint32_t commonEncodingsArraySectionOffset() const {
234     return _addressSpace.get32(_addr +
235                                offsetof(unwind_info_section_header,
236                                         commonEncodingsArraySectionOffset));
237   }
238   uint32_t commonEncodingsArrayCount() const {
239     return _addressSpace.get32(_addr + offsetof(unwind_info_section_header,
240                                                 commonEncodingsArrayCount));
241   }
242   uint32_t personalityArraySectionOffset() const {
243     return _addressSpace.get32(_addr + offsetof(unwind_info_section_header,
244                                                 personalityArraySectionOffset));
245   }
246   uint32_t personalityArrayCount() const {
247     return _addressSpace.get32(
248         _addr + offsetof(unwind_info_section_header, personalityArrayCount));
249   }
250   uint32_t indexSectionOffset() const {
251     return _addressSpace.get32(
252         _addr + offsetof(unwind_info_section_header, indexSectionOffset));
253   }
254   uint32_t indexCount() const {
255     return _addressSpace.get32(
256         _addr + offsetof(unwind_info_section_header, indexCount));
257   }
258 
259 private:
260   A                     &_addressSpace;
261   typename A::pint_t     _addr;
262 };
263 
264 template <typename A> class UnwindSectionIndexArray {
265 public:
266   UnwindSectionIndexArray(A &addressSpace, typename A::pint_t addr)
267       : _addressSpace(addressSpace), _addr(addr) {}
268 
269   uint32_t functionOffset(uint32_t index) const {
270     return _addressSpace.get32(
271         _addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
272                               functionOffset));
273   }
274   uint32_t secondLevelPagesSectionOffset(uint32_t index) const {
275     return _addressSpace.get32(
276         _addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
277                               secondLevelPagesSectionOffset));
278   }
279   uint32_t lsdaIndexArraySectionOffset(uint32_t index) const {
280     return _addressSpace.get32(
281         _addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
282                               lsdaIndexArraySectionOffset));
283   }
284 
285 private:
286   A                   &_addressSpace;
287   typename A::pint_t   _addr;
288 };
289 
290 template <typename A> class UnwindSectionRegularPageHeader {
291 public:
292   UnwindSectionRegularPageHeader(A &addressSpace, typename A::pint_t addr)
293       : _addressSpace(addressSpace), _addr(addr) {}
294 
295   uint32_t kind() const {
296     return _addressSpace.get32(
297         _addr + offsetof(unwind_info_regular_second_level_page_header, kind));
298   }
299   uint16_t entryPageOffset() const {
300     return _addressSpace.get16(
301         _addr + offsetof(unwind_info_regular_second_level_page_header,
302                          entryPageOffset));
303   }
304   uint16_t entryCount() const {
305     return _addressSpace.get16(
306         _addr +
307         offsetof(unwind_info_regular_second_level_page_header, entryCount));
308   }
309 
310 private:
311   A &_addressSpace;
312   typename A::pint_t _addr;
313 };
314 
315 template <typename A> class UnwindSectionRegularArray {
316 public:
317   UnwindSectionRegularArray(A &addressSpace, typename A::pint_t addr)
318       : _addressSpace(addressSpace), _addr(addr) {}
319 
320   uint32_t functionOffset(uint32_t index) const {
321     return _addressSpace.get32(
322         _addr + arrayoffsetof(unwind_info_regular_second_level_entry, index,
323                               functionOffset));
324   }
325   uint32_t encoding(uint32_t index) const {
326     return _addressSpace.get32(
327         _addr +
328         arrayoffsetof(unwind_info_regular_second_level_entry, index, encoding));
329   }
330 
331 private:
332   A &_addressSpace;
333   typename A::pint_t _addr;
334 };
335 
336 template <typename A> class UnwindSectionCompressedPageHeader {
337 public:
338   UnwindSectionCompressedPageHeader(A &addressSpace, typename A::pint_t addr)
339       : _addressSpace(addressSpace), _addr(addr) {}
340 
341   uint32_t kind() const {
342     return _addressSpace.get32(
343         _addr +
344         offsetof(unwind_info_compressed_second_level_page_header, kind));
345   }
346   uint16_t entryPageOffset() const {
347     return _addressSpace.get16(
348         _addr + offsetof(unwind_info_compressed_second_level_page_header,
349                          entryPageOffset));
350   }
351   uint16_t entryCount() const {
352     return _addressSpace.get16(
353         _addr +
354         offsetof(unwind_info_compressed_second_level_page_header, entryCount));
355   }
356   uint16_t encodingsPageOffset() const {
357     return _addressSpace.get16(
358         _addr + offsetof(unwind_info_compressed_second_level_page_header,
359                          encodingsPageOffset));
360   }
361   uint16_t encodingsCount() const {
362     return _addressSpace.get16(
363         _addr + offsetof(unwind_info_compressed_second_level_page_header,
364                          encodingsCount));
365   }
366 
367 private:
368   A &_addressSpace;
369   typename A::pint_t _addr;
370 };
371 
372 template <typename A> class UnwindSectionCompressedArray {
373 public:
374   UnwindSectionCompressedArray(A &addressSpace, typename A::pint_t addr)
375       : _addressSpace(addressSpace), _addr(addr) {}
376 
377   uint32_t functionOffset(uint32_t index) const {
378     return UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET(
379         _addressSpace.get32(_addr + index * sizeof(uint32_t)));
380   }
381   uint16_t encodingIndex(uint32_t index) const {
382     return UNWIND_INFO_COMPRESSED_ENTRY_ENCODING_INDEX(
383         _addressSpace.get32(_addr + index * sizeof(uint32_t)));
384   }
385 
386 private:
387   A &_addressSpace;
388   typename A::pint_t _addr;
389 };
390 
391 template <typename A> class UnwindSectionLsdaArray {
392 public:
393   UnwindSectionLsdaArray(A &addressSpace, typename A::pint_t addr)
394       : _addressSpace(addressSpace), _addr(addr) {}
395 
396   uint32_t functionOffset(uint32_t index) const {
397     return _addressSpace.get32(
398         _addr + arrayoffsetof(unwind_info_section_header_lsda_index_entry,
399                               index, functionOffset));
400   }
401   uint32_t lsdaOffset(uint32_t index) const {
402     return _addressSpace.get32(
403         _addr + arrayoffsetof(unwind_info_section_header_lsda_index_entry,
404                               index, lsdaOffset));
405   }
406 
407 private:
408   A                   &_addressSpace;
409   typename A::pint_t   _addr;
410 };
411 #endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
412 
413 class _LIBUNWIND_HIDDEN AbstractUnwindCursor {
414 public:
415   // NOTE: provide a class specific placement deallocation function (S5.3.4 p20)
416   // This avoids an unnecessary dependency to libc++abi.
417   void operator delete(void *, size_t) {}
418 
419   virtual ~AbstractUnwindCursor() {}
420   virtual bool validReg(int) { _LIBUNWIND_ABORT("validReg not implemented"); }
421   virtual unw_word_t getReg(int) { _LIBUNWIND_ABORT("getReg not implemented"); }
422   virtual void setReg(int, unw_word_t) {
423     _LIBUNWIND_ABORT("setReg not implemented");
424   }
425   virtual bool validFloatReg(int) {
426     _LIBUNWIND_ABORT("validFloatReg not implemented");
427   }
428   virtual unw_fpreg_t getFloatReg(int) {
429     _LIBUNWIND_ABORT("getFloatReg not implemented");
430   }
431   virtual void setFloatReg(int, unw_fpreg_t) {
432     _LIBUNWIND_ABORT("setFloatReg not implemented");
433   }
434   virtual int step() { _LIBUNWIND_ABORT("step not implemented"); }
435   virtual void getInfo(unw_proc_info_t *) {
436     _LIBUNWIND_ABORT("getInfo not implemented");
437   }
438   virtual void jumpto() { _LIBUNWIND_ABORT("jumpto not implemented"); }
439   virtual bool isSignalFrame() {
440     _LIBUNWIND_ABORT("isSignalFrame not implemented");
441   }
442   virtual bool getFunctionName(char *, size_t, unw_word_t *) {
443     _LIBUNWIND_ABORT("getFunctionName not implemented");
444   }
445   virtual void setInfoBasedOnIPRegister(bool = false) {
446     _LIBUNWIND_ABORT("setInfoBasedOnIPRegister not implemented");
447   }
448   virtual const char *getRegisterName(int) {
449     _LIBUNWIND_ABORT("getRegisterName not implemented");
450   }
451 #ifdef __arm__
452   virtual void saveVFPAsX() { _LIBUNWIND_ABORT("saveVFPAsX not implemented"); }
453 #endif
454 };
455 
456 #if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) && defined(_WIN32)
457 
458 /// \c UnwindCursor contains all state (including all register values) during
459 /// an unwind.  This is normally stack-allocated inside a unw_cursor_t.
460 template <typename A, typename R>
461 class UnwindCursor : public AbstractUnwindCursor {
462   typedef typename A::pint_t pint_t;
463 public:
464                       UnwindCursor(unw_context_t *context, A &as);
465                       UnwindCursor(CONTEXT *context, A &as);
466                       UnwindCursor(A &as, void *threadArg);
467   virtual             ~UnwindCursor() {}
468   virtual bool        validReg(int);
469   virtual unw_word_t  getReg(int);
470   virtual void        setReg(int, unw_word_t);
471   virtual bool        validFloatReg(int);
472   virtual unw_fpreg_t getFloatReg(int);
473   virtual void        setFloatReg(int, unw_fpreg_t);
474   virtual int         step();
475   virtual void        getInfo(unw_proc_info_t *);
476   virtual void        jumpto();
477   virtual bool        isSignalFrame();
478   virtual bool        getFunctionName(char *buf, size_t len, unw_word_t *off);
479   virtual void        setInfoBasedOnIPRegister(bool isReturnAddress = false);
480   virtual const char *getRegisterName(int num);
481 #ifdef __arm__
482   virtual void        saveVFPAsX();
483 #endif
484 
485   DISPATCHER_CONTEXT *getDispatcherContext() { return &_dispContext; }
486   void setDispatcherContext(DISPATCHER_CONTEXT *disp) { _dispContext = *disp; }
487 
488   // libunwind does not and should not depend on C++ library which means that we
489   // need our own defition of inline placement new.
490   static void *operator new(size_t, UnwindCursor<A, R> *p) { return p; }
491 
492 private:
493 
494   pint_t getLastPC() const { return _dispContext.ControlPc; }
495   void setLastPC(pint_t pc) { _dispContext.ControlPc = pc; }
496   RUNTIME_FUNCTION *lookUpSEHUnwindInfo(pint_t pc, pint_t *base) {
497     _dispContext.FunctionEntry = RtlLookupFunctionEntry(pc,
498                                                         &_dispContext.ImageBase,
499                                                         _dispContext.HistoryTable);
500     *base = _dispContext.ImageBase;
501     return _dispContext.FunctionEntry;
502   }
503   bool getInfoFromSEH(pint_t pc);
504   int stepWithSEHData() {
505     _dispContext.LanguageHandler = RtlVirtualUnwind(UNW_FLAG_UHANDLER,
506                                                     _dispContext.ImageBase,
507                                                     _dispContext.ControlPc,
508                                                     _dispContext.FunctionEntry,
509                                                     _dispContext.ContextRecord,
510                                                     &_dispContext.HandlerData,
511                                                     &_dispContext.EstablisherFrame,
512                                                     NULL);
513     // Update some fields of the unwind info now, since we have them.
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     return UNW_STEP_SUCCESS;
520   }
521 
522   A                   &_addressSpace;
523   unw_proc_info_t      _info;
524   DISPATCHER_CONTEXT   _dispContext;
525   CONTEXT              _msContext;
526   UNWIND_HISTORY_TABLE _histTable;
527   bool                 _unwindInfoMissing;
528 };
529 
530 
531 template <typename A, typename R>
532 UnwindCursor<A, R>::UnwindCursor(unw_context_t *context, A &as)
533     : _addressSpace(as), _unwindInfoMissing(false) {
534   static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
535                 "UnwindCursor<> does not fit in unw_cursor_t");
536   static_assert((alignof(UnwindCursor<A, R>) <= alignof(unw_cursor_t)),
537                 "UnwindCursor<> requires more alignment than unw_cursor_t");
538   memset(&_info, 0, sizeof(_info));
539   memset(&_histTable, 0, sizeof(_histTable));
540   _dispContext.ContextRecord = &_msContext;
541   _dispContext.HistoryTable = &_histTable;
542   // Initialize MS context from ours.
543   R r(context);
544   _msContext.ContextFlags = CONTEXT_CONTROL|CONTEXT_INTEGER|CONTEXT_FLOATING_POINT;
545 #if defined(_LIBUNWIND_TARGET_X86_64)
546   _msContext.Rax = r.getRegister(UNW_X86_64_RAX);
547   _msContext.Rcx = r.getRegister(UNW_X86_64_RCX);
548   _msContext.Rdx = r.getRegister(UNW_X86_64_RDX);
549   _msContext.Rbx = r.getRegister(UNW_X86_64_RBX);
550   _msContext.Rsp = r.getRegister(UNW_X86_64_RSP);
551   _msContext.Rbp = r.getRegister(UNW_X86_64_RBP);
552   _msContext.Rsi = r.getRegister(UNW_X86_64_RSI);
553   _msContext.Rdi = r.getRegister(UNW_X86_64_RDI);
554   _msContext.R8 = r.getRegister(UNW_X86_64_R8);
555   _msContext.R9 = r.getRegister(UNW_X86_64_R9);
556   _msContext.R10 = r.getRegister(UNW_X86_64_R10);
557   _msContext.R11 = r.getRegister(UNW_X86_64_R11);
558   _msContext.R12 = r.getRegister(UNW_X86_64_R12);
559   _msContext.R13 = r.getRegister(UNW_X86_64_R13);
560   _msContext.R14 = r.getRegister(UNW_X86_64_R14);
561   _msContext.R15 = r.getRegister(UNW_X86_64_R15);
562   _msContext.Rip = r.getRegister(UNW_REG_IP);
563   union {
564     v128 v;
565     M128A m;
566   } t;
567   t.v = r.getVectorRegister(UNW_X86_64_XMM0);
568   _msContext.Xmm0 = t.m;
569   t.v = r.getVectorRegister(UNW_X86_64_XMM1);
570   _msContext.Xmm1 = t.m;
571   t.v = r.getVectorRegister(UNW_X86_64_XMM2);
572   _msContext.Xmm2 = t.m;
573   t.v = r.getVectorRegister(UNW_X86_64_XMM3);
574   _msContext.Xmm3 = t.m;
575   t.v = r.getVectorRegister(UNW_X86_64_XMM4);
576   _msContext.Xmm4 = t.m;
577   t.v = r.getVectorRegister(UNW_X86_64_XMM5);
578   _msContext.Xmm5 = t.m;
579   t.v = r.getVectorRegister(UNW_X86_64_XMM6);
580   _msContext.Xmm6 = t.m;
581   t.v = r.getVectorRegister(UNW_X86_64_XMM7);
582   _msContext.Xmm7 = t.m;
583   t.v = r.getVectorRegister(UNW_X86_64_XMM8);
584   _msContext.Xmm8 = t.m;
585   t.v = r.getVectorRegister(UNW_X86_64_XMM9);
586   _msContext.Xmm9 = t.m;
587   t.v = r.getVectorRegister(UNW_X86_64_XMM10);
588   _msContext.Xmm10 = t.m;
589   t.v = r.getVectorRegister(UNW_X86_64_XMM11);
590   _msContext.Xmm11 = t.m;
591   t.v = r.getVectorRegister(UNW_X86_64_XMM12);
592   _msContext.Xmm12 = t.m;
593   t.v = r.getVectorRegister(UNW_X86_64_XMM13);
594   _msContext.Xmm13 = t.m;
595   t.v = r.getVectorRegister(UNW_X86_64_XMM14);
596   _msContext.Xmm14 = t.m;
597   t.v = r.getVectorRegister(UNW_X86_64_XMM15);
598   _msContext.Xmm15 = t.m;
599 #elif defined(_LIBUNWIND_TARGET_ARM)
600   _msContext.R0 = r.getRegister(UNW_ARM_R0);
601   _msContext.R1 = r.getRegister(UNW_ARM_R1);
602   _msContext.R2 = r.getRegister(UNW_ARM_R2);
603   _msContext.R3 = r.getRegister(UNW_ARM_R3);
604   _msContext.R4 = r.getRegister(UNW_ARM_R4);
605   _msContext.R5 = r.getRegister(UNW_ARM_R5);
606   _msContext.R6 = r.getRegister(UNW_ARM_R6);
607   _msContext.R7 = r.getRegister(UNW_ARM_R7);
608   _msContext.R8 = r.getRegister(UNW_ARM_R8);
609   _msContext.R9 = r.getRegister(UNW_ARM_R9);
610   _msContext.R10 = r.getRegister(UNW_ARM_R10);
611   _msContext.R11 = r.getRegister(UNW_ARM_R11);
612   _msContext.R12 = r.getRegister(UNW_ARM_R12);
613   _msContext.Sp = r.getRegister(UNW_ARM_SP);
614   _msContext.Lr = r.getRegister(UNW_ARM_LR);
615   _msContext.Pc = r.getRegister(UNW_ARM_IP);
616   for (int i = UNW_ARM_D0; i <= UNW_ARM_D31; ++i) {
617     union {
618       uint64_t w;
619       double d;
620     } d;
621     d.d = r.getFloatRegister(i);
622     _msContext.D[i - UNW_ARM_D0] = d.w;
623   }
624 #elif defined(_LIBUNWIND_TARGET_AARCH64)
625   for (int i = UNW_ARM64_X0; i <= UNW_ARM64_X30; ++i)
626     _msContext.X[i - UNW_ARM64_X0] = r.getRegister(i);
627   _msContext.Sp = r.getRegister(UNW_REG_SP);
628   _msContext.Pc = r.getRegister(UNW_REG_IP);
629   for (int i = UNW_ARM64_D0; i <= UNW_ARM64_D31; ++i)
630     _msContext.V[i - UNW_ARM64_D0].D[0] = r.getFloatRegister(i);
631 #endif
632 }
633 
634 template <typename A, typename R>
635 UnwindCursor<A, R>::UnwindCursor(CONTEXT *context, A &as)
636     : _addressSpace(as), _unwindInfoMissing(false) {
637   static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
638                 "UnwindCursor<> does not fit in unw_cursor_t");
639   memset(&_info, 0, sizeof(_info));
640   memset(&_histTable, 0, sizeof(_histTable));
641   _dispContext.ContextRecord = &_msContext;
642   _dispContext.HistoryTable = &_histTable;
643   _msContext = *context;
644 }
645 
646 
647 template <typename A, typename R>
648 bool UnwindCursor<A, R>::validReg(int regNum) {
649   if (regNum == UNW_REG_IP || regNum == UNW_REG_SP) return true;
650 #if defined(_LIBUNWIND_TARGET_X86_64)
651   if (regNum >= UNW_X86_64_RAX && regNum <= UNW_X86_64_R15) return true;
652 #elif defined(_LIBUNWIND_TARGET_ARM)
653   if (regNum >= UNW_ARM_R0 && regNum <= UNW_ARM_R15) return true;
654 #elif defined(_LIBUNWIND_TARGET_AARCH64)
655   if (regNum >= UNW_ARM64_X0 && regNum <= UNW_ARM64_X30) return true;
656 #endif
657   return false;
658 }
659 
660 template <typename A, typename R>
661 unw_word_t UnwindCursor<A, R>::getReg(int regNum) {
662   switch (regNum) {
663 #if defined(_LIBUNWIND_TARGET_X86_64)
664   case UNW_REG_IP: return _msContext.Rip;
665   case UNW_X86_64_RAX: return _msContext.Rax;
666   case UNW_X86_64_RDX: return _msContext.Rdx;
667   case UNW_X86_64_RCX: return _msContext.Rcx;
668   case UNW_X86_64_RBX: return _msContext.Rbx;
669   case UNW_REG_SP:
670   case UNW_X86_64_RSP: return _msContext.Rsp;
671   case UNW_X86_64_RBP: return _msContext.Rbp;
672   case UNW_X86_64_RSI: return _msContext.Rsi;
673   case UNW_X86_64_RDI: return _msContext.Rdi;
674   case UNW_X86_64_R8: return _msContext.R8;
675   case UNW_X86_64_R9: return _msContext.R9;
676   case UNW_X86_64_R10: return _msContext.R10;
677   case UNW_X86_64_R11: return _msContext.R11;
678   case UNW_X86_64_R12: return _msContext.R12;
679   case UNW_X86_64_R13: return _msContext.R13;
680   case UNW_X86_64_R14: return _msContext.R14;
681   case UNW_X86_64_R15: return _msContext.R15;
682 #elif defined(_LIBUNWIND_TARGET_ARM)
683   case UNW_ARM_R0: return _msContext.R0;
684   case UNW_ARM_R1: return _msContext.R1;
685   case UNW_ARM_R2: return _msContext.R2;
686   case UNW_ARM_R3: return _msContext.R3;
687   case UNW_ARM_R4: return _msContext.R4;
688   case UNW_ARM_R5: return _msContext.R5;
689   case UNW_ARM_R6: return _msContext.R6;
690   case UNW_ARM_R7: return _msContext.R7;
691   case UNW_ARM_R8: return _msContext.R8;
692   case UNW_ARM_R9: return _msContext.R9;
693   case UNW_ARM_R10: return _msContext.R10;
694   case UNW_ARM_R11: return _msContext.R11;
695   case UNW_ARM_R12: return _msContext.R12;
696   case UNW_REG_SP:
697   case UNW_ARM_SP: return _msContext.Sp;
698   case UNW_ARM_LR: return _msContext.Lr;
699   case UNW_REG_IP:
700   case UNW_ARM_IP: return _msContext.Pc;
701 #elif defined(_LIBUNWIND_TARGET_AARCH64)
702   case UNW_REG_SP: return _msContext.Sp;
703   case UNW_REG_IP: return _msContext.Pc;
704   default: return _msContext.X[regNum - UNW_ARM64_X0];
705 #endif
706   }
707   _LIBUNWIND_ABORT("unsupported register");
708 }
709 
710 template <typename A, typename R>
711 void UnwindCursor<A, R>::setReg(int regNum, unw_word_t value) {
712   switch (regNum) {
713 #if defined(_LIBUNWIND_TARGET_X86_64)
714   case UNW_REG_IP: _msContext.Rip = value; break;
715   case UNW_X86_64_RAX: _msContext.Rax = value; break;
716   case UNW_X86_64_RDX: _msContext.Rdx = value; break;
717   case UNW_X86_64_RCX: _msContext.Rcx = value; break;
718   case UNW_X86_64_RBX: _msContext.Rbx = value; break;
719   case UNW_REG_SP:
720   case UNW_X86_64_RSP: _msContext.Rsp = value; break;
721   case UNW_X86_64_RBP: _msContext.Rbp = value; break;
722   case UNW_X86_64_RSI: _msContext.Rsi = value; break;
723   case UNW_X86_64_RDI: _msContext.Rdi = value; break;
724   case UNW_X86_64_R8: _msContext.R8 = value; break;
725   case UNW_X86_64_R9: _msContext.R9 = value; break;
726   case UNW_X86_64_R10: _msContext.R10 = value; break;
727   case UNW_X86_64_R11: _msContext.R11 = value; break;
728   case UNW_X86_64_R12: _msContext.R12 = value; break;
729   case UNW_X86_64_R13: _msContext.R13 = value; break;
730   case UNW_X86_64_R14: _msContext.R14 = value; break;
731   case UNW_X86_64_R15: _msContext.R15 = value; break;
732 #elif defined(_LIBUNWIND_TARGET_ARM)
733   case UNW_ARM_R0: _msContext.R0 = value; break;
734   case UNW_ARM_R1: _msContext.R1 = value; break;
735   case UNW_ARM_R2: _msContext.R2 = value; break;
736   case UNW_ARM_R3: _msContext.R3 = value; break;
737   case UNW_ARM_R4: _msContext.R4 = value; break;
738   case UNW_ARM_R5: _msContext.R5 = value; break;
739   case UNW_ARM_R6: _msContext.R6 = value; break;
740   case UNW_ARM_R7: _msContext.R7 = value; break;
741   case UNW_ARM_R8: _msContext.R8 = value; break;
742   case UNW_ARM_R9: _msContext.R9 = value; break;
743   case UNW_ARM_R10: _msContext.R10 = value; break;
744   case UNW_ARM_R11: _msContext.R11 = value; break;
745   case UNW_ARM_R12: _msContext.R12 = value; break;
746   case UNW_REG_SP:
747   case UNW_ARM_SP: _msContext.Sp = value; break;
748   case UNW_ARM_LR: _msContext.Lr = value; break;
749   case UNW_REG_IP:
750   case UNW_ARM_IP: _msContext.Pc = value; break;
751 #elif defined(_LIBUNWIND_TARGET_AARCH64)
752   case UNW_REG_SP: _msContext.Sp = value; break;
753   case UNW_REG_IP: _msContext.Pc = value; break;
754   case UNW_ARM64_X0:
755   case UNW_ARM64_X1:
756   case UNW_ARM64_X2:
757   case UNW_ARM64_X3:
758   case UNW_ARM64_X4:
759   case UNW_ARM64_X5:
760   case UNW_ARM64_X6:
761   case UNW_ARM64_X7:
762   case UNW_ARM64_X8:
763   case UNW_ARM64_X9:
764   case UNW_ARM64_X10:
765   case UNW_ARM64_X11:
766   case UNW_ARM64_X12:
767   case UNW_ARM64_X13:
768   case UNW_ARM64_X14:
769   case UNW_ARM64_X15:
770   case UNW_ARM64_X16:
771   case UNW_ARM64_X17:
772   case UNW_ARM64_X18:
773   case UNW_ARM64_X19:
774   case UNW_ARM64_X20:
775   case UNW_ARM64_X21:
776   case UNW_ARM64_X22:
777   case UNW_ARM64_X23:
778   case UNW_ARM64_X24:
779   case UNW_ARM64_X25:
780   case UNW_ARM64_X26:
781   case UNW_ARM64_X27:
782   case UNW_ARM64_X28:
783   case UNW_ARM64_FP:
784   case UNW_ARM64_LR: _msContext.X[regNum - UNW_ARM64_X0] = value; break;
785 #endif
786   default:
787     _LIBUNWIND_ABORT("unsupported register");
788   }
789 }
790 
791 template <typename A, typename R>
792 bool UnwindCursor<A, R>::validFloatReg(int regNum) {
793 #if defined(_LIBUNWIND_TARGET_ARM)
794   if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) return true;
795   if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) return true;
796 #elif defined(_LIBUNWIND_TARGET_AARCH64)
797   if (regNum >= UNW_ARM64_D0 && regNum <= UNW_ARM64_D31) return true;
798 #else
799   (void)regNum;
800 #endif
801   return false;
802 }
803 
804 template <typename A, typename R>
805 unw_fpreg_t UnwindCursor<A, R>::getFloatReg(int regNum) {
806 #if defined(_LIBUNWIND_TARGET_ARM)
807   if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) {
808     union {
809       uint32_t w;
810       float f;
811     } d;
812     d.w = _msContext.S[regNum - UNW_ARM_S0];
813     return d.f;
814   }
815   if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) {
816     union {
817       uint64_t w;
818       double d;
819     } d;
820     d.w = _msContext.D[regNum - UNW_ARM_D0];
821     return d.d;
822   }
823   _LIBUNWIND_ABORT("unsupported float register");
824 #elif defined(_LIBUNWIND_TARGET_AARCH64)
825   return _msContext.V[regNum - UNW_ARM64_D0].D[0];
826 #else
827   (void)regNum;
828   _LIBUNWIND_ABORT("float registers unimplemented");
829 #endif
830 }
831 
832 template <typename A, typename R>
833 void UnwindCursor<A, R>::setFloatReg(int regNum, unw_fpreg_t value) {
834 #if defined(_LIBUNWIND_TARGET_ARM)
835   if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) {
836     union {
837       uint32_t w;
838       float f;
839     } d;
840     d.f = value;
841     _msContext.S[regNum - UNW_ARM_S0] = d.w;
842   }
843   if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) {
844     union {
845       uint64_t w;
846       double d;
847     } d;
848     d.d = value;
849     _msContext.D[regNum - UNW_ARM_D0] = d.w;
850   }
851   _LIBUNWIND_ABORT("unsupported float register");
852 #elif defined(_LIBUNWIND_TARGET_AARCH64)
853   _msContext.V[regNum - UNW_ARM64_D0].D[0] = value;
854 #else
855   (void)regNum;
856   (void)value;
857   _LIBUNWIND_ABORT("float registers unimplemented");
858 #endif
859 }
860 
861 template <typename A, typename R> void UnwindCursor<A, R>::jumpto() {
862   RtlRestoreContext(&_msContext, nullptr);
863 }
864 
865 #ifdef __arm__
866 template <typename A, typename R> void UnwindCursor<A, R>::saveVFPAsX() {}
867 #endif
868 
869 template <typename A, typename R>
870 const char *UnwindCursor<A, R>::getRegisterName(int regNum) {
871   return R::getRegisterName(regNum);
872 }
873 
874 template <typename A, typename R> bool UnwindCursor<A, R>::isSignalFrame() {
875   return false;
876 }
877 
878 #else  // !defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) || !defined(_WIN32)
879 
880 /// UnwindCursor contains all state (including all register values) during
881 /// an unwind.  This is normally stack allocated inside a unw_cursor_t.
882 template <typename A, typename R>
883 class UnwindCursor : public AbstractUnwindCursor{
884   typedef typename A::pint_t pint_t;
885 public:
886                       UnwindCursor(unw_context_t *context, A &as);
887                       UnwindCursor(A &as, void *threadArg);
888   virtual             ~UnwindCursor() {}
889   virtual bool        validReg(int);
890   virtual unw_word_t  getReg(int);
891   virtual void        setReg(int, unw_word_t);
892   virtual bool        validFloatReg(int);
893   virtual unw_fpreg_t getFloatReg(int);
894   virtual void        setFloatReg(int, unw_fpreg_t);
895   virtual int         step();
896   virtual void        getInfo(unw_proc_info_t *);
897   virtual void        jumpto();
898   virtual bool        isSignalFrame();
899   virtual bool        getFunctionName(char *buf, size_t len, unw_word_t *off);
900   virtual void        setInfoBasedOnIPRegister(bool isReturnAddress = false);
901   virtual const char *getRegisterName(int num);
902 #ifdef __arm__
903   virtual void        saveVFPAsX();
904 #endif
905 
906   // libunwind does not and should not depend on C++ library which means that we
907   // need our own defition of inline placement new.
908   static void *operator new(size_t, UnwindCursor<A, R> *p) { return p; }
909 
910 private:
911 
912 #if defined(_LIBUNWIND_ARM_EHABI)
913   bool getInfoFromEHABISection(pint_t pc, const UnwindInfoSections &sects);
914 
915   int stepWithEHABI() {
916     size_t len = 0;
917     size_t off = 0;
918     // FIXME: Calling decode_eht_entry() here is violating the libunwind
919     // abstraction layer.
920     const uint32_t *ehtp =
921         decode_eht_entry(reinterpret_cast<const uint32_t *>(_info.unwind_info),
922                          &off, &len);
923     if (_Unwind_VRS_Interpret((_Unwind_Context *)this, ehtp, off, len) !=
924             _URC_CONTINUE_UNWIND)
925       return UNW_STEP_END;
926     return UNW_STEP_SUCCESS;
927   }
928 #endif
929 
930 #if defined(_LIBUNWIND_TARGET_LINUX) && defined(_LIBUNWIND_TARGET_AARCH64)
931   bool setInfoForSigReturn() {
932     R dummy;
933     return setInfoForSigReturn(dummy);
934   }
935   int stepThroughSigReturn() {
936     R dummy;
937     return stepThroughSigReturn(dummy);
938   }
939   bool setInfoForSigReturn(Registers_arm64 &);
940   int stepThroughSigReturn(Registers_arm64 &);
941   template <typename Registers> bool setInfoForSigReturn(Registers &) {
942     return false;
943   }
944   template <typename Registers> int stepThroughSigReturn(Registers &) {
945     return UNW_STEP_END;
946   }
947 #endif
948 
949 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
950   bool getInfoFromFdeCie(const typename CFI_Parser<A>::FDE_Info &fdeInfo,
951                          const typename CFI_Parser<A>::CIE_Info &cieInfo,
952                          pint_t pc, uintptr_t dso_base);
953   bool getInfoFromDwarfSection(pint_t pc, const UnwindInfoSections &sects,
954                                             uint32_t fdeSectionOffsetHint=0);
955   int stepWithDwarfFDE() {
956     return DwarfInstructions<A, R>::stepWithDwarf(_addressSpace,
957                                               (pint_t)this->getReg(UNW_REG_IP),
958                                               (pint_t)_info.unwind_info,
959                                               _registers, _isSignalFrame);
960   }
961 #endif
962 
963 #if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
964   bool getInfoFromCompactEncodingSection(pint_t pc,
965                                             const UnwindInfoSections &sects);
966   int stepWithCompactEncoding() {
967   #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
968     if ( compactSaysUseDwarf() )
969       return stepWithDwarfFDE();
970   #endif
971     R dummy;
972     return stepWithCompactEncoding(dummy);
973   }
974 
975 #if defined(_LIBUNWIND_TARGET_X86_64)
976   int stepWithCompactEncoding(Registers_x86_64 &) {
977     return CompactUnwinder_x86_64<A>::stepWithCompactEncoding(
978         _info.format, _info.start_ip, _addressSpace, _registers);
979   }
980 #endif
981 
982 #if defined(_LIBUNWIND_TARGET_I386)
983   int stepWithCompactEncoding(Registers_x86 &) {
984     return CompactUnwinder_x86<A>::stepWithCompactEncoding(
985         _info.format, (uint32_t)_info.start_ip, _addressSpace, _registers);
986   }
987 #endif
988 
989 #if defined(_LIBUNWIND_TARGET_PPC)
990   int stepWithCompactEncoding(Registers_ppc &) {
991     return UNW_EINVAL;
992   }
993 #endif
994 
995 #if defined(_LIBUNWIND_TARGET_PPC64)
996   int stepWithCompactEncoding(Registers_ppc64 &) {
997     return UNW_EINVAL;
998   }
999 #endif
1000 
1001 
1002 #if defined(_LIBUNWIND_TARGET_AARCH64)
1003   int stepWithCompactEncoding(Registers_arm64 &) {
1004     return CompactUnwinder_arm64<A>::stepWithCompactEncoding(
1005         _info.format, _info.start_ip, _addressSpace, _registers);
1006   }
1007 #endif
1008 
1009 #if defined(_LIBUNWIND_TARGET_MIPS_O32)
1010   int stepWithCompactEncoding(Registers_mips_o32 &) {
1011     return UNW_EINVAL;
1012   }
1013 #endif
1014 
1015 #if defined(_LIBUNWIND_TARGET_MIPS_NEWABI)
1016   int stepWithCompactEncoding(Registers_mips_newabi &) {
1017     return UNW_EINVAL;
1018   }
1019 #endif
1020 
1021 #if defined(_LIBUNWIND_TARGET_SPARC)
1022   int stepWithCompactEncoding(Registers_sparc &) { return UNW_EINVAL; }
1023 #endif
1024 
1025 #if defined (_LIBUNWIND_TARGET_RISCV)
1026   int stepWithCompactEncoding(Registers_riscv &) {
1027     return UNW_EINVAL;
1028   }
1029 #endif
1030 
1031   bool compactSaysUseDwarf(uint32_t *offset=NULL) const {
1032     R dummy;
1033     return compactSaysUseDwarf(dummy, offset);
1034   }
1035 
1036 #if defined(_LIBUNWIND_TARGET_X86_64)
1037   bool compactSaysUseDwarf(Registers_x86_64 &, uint32_t *offset) const {
1038     if ((_info.format & UNWIND_X86_64_MODE_MASK) == UNWIND_X86_64_MODE_DWARF) {
1039       if (offset)
1040         *offset = (_info.format & UNWIND_X86_64_DWARF_SECTION_OFFSET);
1041       return true;
1042     }
1043     return false;
1044   }
1045 #endif
1046 
1047 #if defined(_LIBUNWIND_TARGET_I386)
1048   bool compactSaysUseDwarf(Registers_x86 &, uint32_t *offset) const {
1049     if ((_info.format & UNWIND_X86_MODE_MASK) == UNWIND_X86_MODE_DWARF) {
1050       if (offset)
1051         *offset = (_info.format & UNWIND_X86_DWARF_SECTION_OFFSET);
1052       return true;
1053     }
1054     return false;
1055   }
1056 #endif
1057 
1058 #if defined(_LIBUNWIND_TARGET_PPC)
1059   bool compactSaysUseDwarf(Registers_ppc &, uint32_t *) const {
1060     return true;
1061   }
1062 #endif
1063 
1064 #if defined(_LIBUNWIND_TARGET_PPC64)
1065   bool compactSaysUseDwarf(Registers_ppc64 &, uint32_t *) const {
1066     return true;
1067   }
1068 #endif
1069 
1070 #if defined(_LIBUNWIND_TARGET_AARCH64)
1071   bool compactSaysUseDwarf(Registers_arm64 &, uint32_t *offset) const {
1072     if ((_info.format & UNWIND_ARM64_MODE_MASK) == UNWIND_ARM64_MODE_DWARF) {
1073       if (offset)
1074         *offset = (_info.format & UNWIND_ARM64_DWARF_SECTION_OFFSET);
1075       return true;
1076     }
1077     return false;
1078   }
1079 #endif
1080 
1081 #if defined(_LIBUNWIND_TARGET_MIPS_O32)
1082   bool compactSaysUseDwarf(Registers_mips_o32 &, uint32_t *) const {
1083     return true;
1084   }
1085 #endif
1086 
1087 #if defined(_LIBUNWIND_TARGET_MIPS_NEWABI)
1088   bool compactSaysUseDwarf(Registers_mips_newabi &, uint32_t *) const {
1089     return true;
1090   }
1091 #endif
1092 
1093 #if defined(_LIBUNWIND_TARGET_SPARC)
1094   bool compactSaysUseDwarf(Registers_sparc &, uint32_t *) const { return true; }
1095 #endif
1096 
1097 #if defined (_LIBUNWIND_TARGET_RISCV)
1098   bool compactSaysUseDwarf(Registers_riscv &, uint32_t *) const {
1099     return true;
1100   }
1101 #endif
1102 
1103 #endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1104 
1105 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1106   compact_unwind_encoding_t dwarfEncoding() const {
1107     R dummy;
1108     return dwarfEncoding(dummy);
1109   }
1110 
1111 #if defined(_LIBUNWIND_TARGET_X86_64)
1112   compact_unwind_encoding_t dwarfEncoding(Registers_x86_64 &) const {
1113     return UNWIND_X86_64_MODE_DWARF;
1114   }
1115 #endif
1116 
1117 #if defined(_LIBUNWIND_TARGET_I386)
1118   compact_unwind_encoding_t dwarfEncoding(Registers_x86 &) const {
1119     return UNWIND_X86_MODE_DWARF;
1120   }
1121 #endif
1122 
1123 #if defined(_LIBUNWIND_TARGET_PPC)
1124   compact_unwind_encoding_t dwarfEncoding(Registers_ppc &) const {
1125     return 0;
1126   }
1127 #endif
1128 
1129 #if defined(_LIBUNWIND_TARGET_PPC64)
1130   compact_unwind_encoding_t dwarfEncoding(Registers_ppc64 &) const {
1131     return 0;
1132   }
1133 #endif
1134 
1135 #if defined(_LIBUNWIND_TARGET_AARCH64)
1136   compact_unwind_encoding_t dwarfEncoding(Registers_arm64 &) const {
1137     return UNWIND_ARM64_MODE_DWARF;
1138   }
1139 #endif
1140 
1141 #if defined(_LIBUNWIND_TARGET_ARM)
1142   compact_unwind_encoding_t dwarfEncoding(Registers_arm &) const {
1143     return 0;
1144   }
1145 #endif
1146 
1147 #if defined (_LIBUNWIND_TARGET_OR1K)
1148   compact_unwind_encoding_t dwarfEncoding(Registers_or1k &) const {
1149     return 0;
1150   }
1151 #endif
1152 
1153 #if defined (_LIBUNWIND_TARGET_HEXAGON)
1154   compact_unwind_encoding_t dwarfEncoding(Registers_hexagon &) const {
1155     return 0;
1156   }
1157 #endif
1158 
1159 #if defined (_LIBUNWIND_TARGET_MIPS_O32)
1160   compact_unwind_encoding_t dwarfEncoding(Registers_mips_o32 &) const {
1161     return 0;
1162   }
1163 #endif
1164 
1165 #if defined (_LIBUNWIND_TARGET_MIPS_NEWABI)
1166   compact_unwind_encoding_t dwarfEncoding(Registers_mips_newabi &) const {
1167     return 0;
1168   }
1169 #endif
1170 
1171 #if defined(_LIBUNWIND_TARGET_SPARC)
1172   compact_unwind_encoding_t dwarfEncoding(Registers_sparc &) const { return 0; }
1173 #endif
1174 
1175 #if defined (_LIBUNWIND_TARGET_SPARC64)
1176   compact_unwind_encoding_t dwarfEncoding(Registers_sparc64 &) const {
1177     return 0;
1178   }
1179 #endif
1180 
1181 #if defined (_LIBUNWIND_TARGET_RISCV)
1182   compact_unwind_encoding_t dwarfEncoding(Registers_riscv &) const {
1183     return 0;
1184   }
1185 #endif
1186 
1187 #endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1188 
1189 #if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1190   // For runtime environments using SEH unwind data without Windows runtime
1191   // support.
1192   pint_t getLastPC() const { /* FIXME: Implement */ return 0; }
1193   void setLastPC(pint_t pc) { /* FIXME: Implement */ }
1194   RUNTIME_FUNCTION *lookUpSEHUnwindInfo(pint_t pc, pint_t *base) {
1195     /* FIXME: Implement */
1196     *base = 0;
1197     return nullptr;
1198   }
1199   bool getInfoFromSEH(pint_t pc);
1200   int stepWithSEHData() { /* FIXME: Implement */ return 0; }
1201 #endif // defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1202 
1203 
1204   A               &_addressSpace;
1205   R                _registers;
1206   unw_proc_info_t  _info;
1207   bool             _unwindInfoMissing;
1208   bool             _isSignalFrame;
1209 #if defined(_LIBUNWIND_TARGET_LINUX) && defined(_LIBUNWIND_TARGET_AARCH64)
1210   bool             _isSigReturn = false;
1211 #endif
1212 };
1213 
1214 
1215 template <typename A, typename R>
1216 UnwindCursor<A, R>::UnwindCursor(unw_context_t *context, A &as)
1217     : _addressSpace(as), _registers(context), _unwindInfoMissing(false),
1218       _isSignalFrame(false) {
1219   static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
1220                 "UnwindCursor<> does not fit in unw_cursor_t");
1221   static_assert((alignof(UnwindCursor<A, R>) <= alignof(unw_cursor_t)),
1222                 "UnwindCursor<> requires more alignment than unw_cursor_t");
1223   memset(&_info, 0, sizeof(_info));
1224 }
1225 
1226 template <typename A, typename R>
1227 UnwindCursor<A, R>::UnwindCursor(A &as, void *)
1228     : _addressSpace(as), _unwindInfoMissing(false), _isSignalFrame(false) {
1229   memset(&_info, 0, sizeof(_info));
1230   // FIXME
1231   // fill in _registers from thread arg
1232 }
1233 
1234 
1235 template <typename A, typename R>
1236 bool UnwindCursor<A, R>::validReg(int regNum) {
1237   return _registers.validRegister(regNum);
1238 }
1239 
1240 template <typename A, typename R>
1241 unw_word_t UnwindCursor<A, R>::getReg(int regNum) {
1242   return _registers.getRegister(regNum);
1243 }
1244 
1245 template <typename A, typename R>
1246 void UnwindCursor<A, R>::setReg(int regNum, unw_word_t value) {
1247   _registers.setRegister(regNum, (typename A::pint_t)value);
1248 }
1249 
1250 template <typename A, typename R>
1251 bool UnwindCursor<A, R>::validFloatReg(int regNum) {
1252   return _registers.validFloatRegister(regNum);
1253 }
1254 
1255 template <typename A, typename R>
1256 unw_fpreg_t UnwindCursor<A, R>::getFloatReg(int regNum) {
1257   return _registers.getFloatRegister(regNum);
1258 }
1259 
1260 template <typename A, typename R>
1261 void UnwindCursor<A, R>::setFloatReg(int regNum, unw_fpreg_t value) {
1262   _registers.setFloatRegister(regNum, value);
1263 }
1264 
1265 template <typename A, typename R> void UnwindCursor<A, R>::jumpto() {
1266   _registers.jumpto();
1267 }
1268 
1269 #ifdef __arm__
1270 template <typename A, typename R> void UnwindCursor<A, R>::saveVFPAsX() {
1271   _registers.saveVFPAsX();
1272 }
1273 #endif
1274 
1275 template <typename A, typename R>
1276 const char *UnwindCursor<A, R>::getRegisterName(int regNum) {
1277   return _registers.getRegisterName(regNum);
1278 }
1279 
1280 template <typename A, typename R> bool UnwindCursor<A, R>::isSignalFrame() {
1281   return _isSignalFrame;
1282 }
1283 
1284 #endif // defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1285 
1286 #if defined(_LIBUNWIND_ARM_EHABI)
1287 template<typename A>
1288 struct EHABISectionIterator {
1289   typedef EHABISectionIterator _Self;
1290 
1291   typedef typename A::pint_t value_type;
1292   typedef typename A::pint_t* pointer;
1293   typedef typename A::pint_t& reference;
1294   typedef size_t size_type;
1295   typedef size_t difference_type;
1296 
1297   static _Self begin(A& addressSpace, const UnwindInfoSections& sects) {
1298     return _Self(addressSpace, sects, 0);
1299   }
1300   static _Self end(A& addressSpace, const UnwindInfoSections& sects) {
1301     return _Self(addressSpace, sects,
1302                  sects.arm_section_length / sizeof(EHABIIndexEntry));
1303   }
1304 
1305   EHABISectionIterator(A& addressSpace, const UnwindInfoSections& sects, size_t i)
1306       : _i(i), _addressSpace(&addressSpace), _sects(&sects) {}
1307 
1308   _Self& operator++() { ++_i; return *this; }
1309   _Self& operator+=(size_t a) { _i += a; return *this; }
1310   _Self& operator--() { assert(_i > 0); --_i; return *this; }
1311   _Self& operator-=(size_t a) { assert(_i >= a); _i -= a; return *this; }
1312 
1313   _Self operator+(size_t a) { _Self out = *this; out._i += a; return out; }
1314   _Self operator-(size_t a) { assert(_i >= a); _Self out = *this; out._i -= a; return out; }
1315 
1316   size_t operator-(const _Self& other) const { return _i - other._i; }
1317 
1318   bool operator==(const _Self& other) const {
1319     assert(_addressSpace == other._addressSpace);
1320     assert(_sects == other._sects);
1321     return _i == other._i;
1322   }
1323 
1324   bool operator!=(const _Self& other) const {
1325     assert(_addressSpace == other._addressSpace);
1326     assert(_sects == other._sects);
1327     return _i != other._i;
1328   }
1329 
1330   typename A::pint_t operator*() const { return functionAddress(); }
1331 
1332   typename A::pint_t functionAddress() const {
1333     typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
1334         EHABIIndexEntry, _i, functionOffset);
1335     return indexAddr + signExtendPrel31(_addressSpace->get32(indexAddr));
1336   }
1337 
1338   typename A::pint_t dataAddress() {
1339     typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
1340         EHABIIndexEntry, _i, data);
1341     return indexAddr;
1342   }
1343 
1344  private:
1345   size_t _i;
1346   A* _addressSpace;
1347   const UnwindInfoSections* _sects;
1348 };
1349 
1350 namespace {
1351 
1352 template <typename A>
1353 EHABISectionIterator<A> EHABISectionUpperBound(
1354     EHABISectionIterator<A> first,
1355     EHABISectionIterator<A> last,
1356     typename A::pint_t value) {
1357   size_t len = last - first;
1358   while (len > 0) {
1359     size_t l2 = len / 2;
1360     EHABISectionIterator<A> m = first + l2;
1361     if (value < *m) {
1362         len = l2;
1363     } else {
1364         first = ++m;
1365         len -= l2 + 1;
1366     }
1367   }
1368   return first;
1369 }
1370 
1371 }
1372 
1373 template <typename A, typename R>
1374 bool UnwindCursor<A, R>::getInfoFromEHABISection(
1375     pint_t pc,
1376     const UnwindInfoSections &sects) {
1377   EHABISectionIterator<A> begin =
1378       EHABISectionIterator<A>::begin(_addressSpace, sects);
1379   EHABISectionIterator<A> end =
1380       EHABISectionIterator<A>::end(_addressSpace, sects);
1381   if (begin == end)
1382     return false;
1383 
1384   EHABISectionIterator<A> itNextPC = EHABISectionUpperBound(begin, end, pc);
1385   if (itNextPC == begin)
1386     return false;
1387   EHABISectionIterator<A> itThisPC = itNextPC - 1;
1388 
1389   pint_t thisPC = itThisPC.functionAddress();
1390   // If an exception is thrown from a function, corresponding to the last entry
1391   // in the table, we don't really know the function extent and have to choose a
1392   // value for nextPC. Choosing max() will allow the range check during trace to
1393   // succeed.
1394   pint_t nextPC = (itNextPC == end) ? UINTPTR_MAX : itNextPC.functionAddress();
1395   pint_t indexDataAddr = itThisPC.dataAddress();
1396 
1397   if (indexDataAddr == 0)
1398     return false;
1399 
1400   uint32_t indexData = _addressSpace.get32(indexDataAddr);
1401   if (indexData == UNW_EXIDX_CANTUNWIND)
1402     return false;
1403 
1404   // If the high bit is set, the exception handling table entry is inline inside
1405   // the index table entry on the second word (aka |indexDataAddr|). Otherwise,
1406   // the table points at an offset in the exception handling table (section 5
1407   // EHABI).
1408   pint_t exceptionTableAddr;
1409   uint32_t exceptionTableData;
1410   bool isSingleWordEHT;
1411   if (indexData & 0x80000000) {
1412     exceptionTableAddr = indexDataAddr;
1413     // TODO(ajwong): Should this data be 0?
1414     exceptionTableData = indexData;
1415     isSingleWordEHT = true;
1416   } else {
1417     exceptionTableAddr = indexDataAddr + signExtendPrel31(indexData);
1418     exceptionTableData = _addressSpace.get32(exceptionTableAddr);
1419     isSingleWordEHT = false;
1420   }
1421 
1422   // Now we know the 3 things:
1423   //   exceptionTableAddr -- exception handler table entry.
1424   //   exceptionTableData -- the data inside the first word of the eht entry.
1425   //   isSingleWordEHT -- whether the entry is in the index.
1426   unw_word_t personalityRoutine = 0xbadf00d;
1427   bool scope32 = false;
1428   uintptr_t lsda;
1429 
1430   // If the high bit in the exception handling table entry is set, the entry is
1431   // in compact form (section 6.3 EHABI).
1432   if (exceptionTableData & 0x80000000) {
1433     // Grab the index of the personality routine from the compact form.
1434     uint32_t choice = (exceptionTableData & 0x0f000000) >> 24;
1435     uint32_t extraWords = 0;
1436     switch (choice) {
1437       case 0:
1438         personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr0;
1439         extraWords = 0;
1440         scope32 = false;
1441         lsda = isSingleWordEHT ? 0 : (exceptionTableAddr + 4);
1442         break;
1443       case 1:
1444         personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr1;
1445         extraWords = (exceptionTableData & 0x00ff0000) >> 16;
1446         scope32 = false;
1447         lsda = exceptionTableAddr + (extraWords + 1) * 4;
1448         break;
1449       case 2:
1450         personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr2;
1451         extraWords = (exceptionTableData & 0x00ff0000) >> 16;
1452         scope32 = true;
1453         lsda = exceptionTableAddr + (extraWords + 1) * 4;
1454         break;
1455       default:
1456         _LIBUNWIND_ABORT("unknown personality routine");
1457         return false;
1458     }
1459 
1460     if (isSingleWordEHT) {
1461       if (extraWords != 0) {
1462         _LIBUNWIND_ABORT("index inlined table detected but pr function "
1463                          "requires extra words");
1464         return false;
1465       }
1466     }
1467   } else {
1468     pint_t personalityAddr =
1469         exceptionTableAddr + signExtendPrel31(exceptionTableData);
1470     personalityRoutine = personalityAddr;
1471 
1472     // ARM EHABI # 6.2, # 9.2
1473     //
1474     //  +---- ehtp
1475     //  v
1476     // +--------------------------------------+
1477     // | +--------+--------+--------+-------+ |
1478     // | |0| prel31 to personalityRoutine   | |
1479     // | +--------+--------+--------+-------+ |
1480     // | |      N |      unwind opcodes     | |  <-- UnwindData
1481     // | +--------+--------+--------+-------+ |
1482     // | | Word 2        unwind opcodes     | |
1483     // | +--------+--------+--------+-------+ |
1484     // | ...                                  |
1485     // | +--------+--------+--------+-------+ |
1486     // | | Word N        unwind opcodes     | |
1487     // | +--------+--------+--------+-------+ |
1488     // | | LSDA                             | |  <-- lsda
1489     // | | ...                              | |
1490     // | +--------+--------+--------+-------+ |
1491     // +--------------------------------------+
1492 
1493     uint32_t *UnwindData = reinterpret_cast<uint32_t*>(exceptionTableAddr) + 1;
1494     uint32_t FirstDataWord = *UnwindData;
1495     size_t N = ((FirstDataWord >> 24) & 0xff);
1496     size_t NDataWords = N + 1;
1497     lsda = reinterpret_cast<uintptr_t>(UnwindData + NDataWords);
1498   }
1499 
1500   _info.start_ip = thisPC;
1501   _info.end_ip = nextPC;
1502   _info.handler = personalityRoutine;
1503   _info.unwind_info = exceptionTableAddr;
1504   _info.lsda = lsda;
1505   // flags is pr_cache.additional. See EHABI #7.2 for definition of bit 0.
1506   _info.flags = (isSingleWordEHT ? 1 : 0) | (scope32 ? 0x2 : 0);  // Use enum?
1507 
1508   return true;
1509 }
1510 #endif
1511 
1512 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1513 template <typename A, typename R>
1514 bool UnwindCursor<A, R>::getInfoFromFdeCie(
1515     const typename CFI_Parser<A>::FDE_Info &fdeInfo,
1516     const typename CFI_Parser<A>::CIE_Info &cieInfo, pint_t pc,
1517     uintptr_t dso_base) {
1518   typename CFI_Parser<A>::PrologInfo prolog;
1519   if (CFI_Parser<A>::parseFDEInstructions(_addressSpace, fdeInfo, cieInfo, pc,
1520                                           R::getArch(), &prolog)) {
1521     // Save off parsed FDE info
1522     _info.start_ip          = fdeInfo.pcStart;
1523     _info.end_ip            = fdeInfo.pcEnd;
1524     _info.lsda              = fdeInfo.lsda;
1525     _info.handler           = cieInfo.personality;
1526     // Some frameless functions need SP altered when resuming in function, so
1527     // propagate spExtraArgSize.
1528     _info.gp                = prolog.spExtraArgSize;
1529     _info.flags             = 0;
1530     _info.format            = dwarfEncoding();
1531     _info.unwind_info       = fdeInfo.fdeStart;
1532     _info.unwind_info_size  = static_cast<uint32_t>(fdeInfo.fdeLength);
1533     _info.extra             = static_cast<unw_word_t>(dso_base);
1534     return true;
1535   }
1536   return false;
1537 }
1538 
1539 template <typename A, typename R>
1540 bool UnwindCursor<A, R>::getInfoFromDwarfSection(pint_t pc,
1541                                                 const UnwindInfoSections &sects,
1542                                                 uint32_t fdeSectionOffsetHint) {
1543   typename CFI_Parser<A>::FDE_Info fdeInfo;
1544   typename CFI_Parser<A>::CIE_Info cieInfo;
1545   bool foundFDE = false;
1546   bool foundInCache = false;
1547   // If compact encoding table gave offset into dwarf section, go directly there
1548   if (fdeSectionOffsetHint != 0) {
1549     foundFDE = CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
1550                                     sects.dwarf_section_length,
1551                                     sects.dwarf_section + fdeSectionOffsetHint,
1552                                     &fdeInfo, &cieInfo);
1553   }
1554 #if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
1555   if (!foundFDE && (sects.dwarf_index_section != 0)) {
1556     foundFDE = EHHeaderParser<A>::findFDE(
1557         _addressSpace, pc, sects.dwarf_index_section,
1558         (uint32_t)sects.dwarf_index_section_length, &fdeInfo, &cieInfo);
1559   }
1560 #endif
1561   if (!foundFDE) {
1562     // otherwise, search cache of previously found FDEs.
1563     pint_t cachedFDE = DwarfFDECache<A>::findFDE(sects.dso_base, pc);
1564     if (cachedFDE != 0) {
1565       foundFDE =
1566           CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
1567                                  sects.dwarf_section_length,
1568                                  cachedFDE, &fdeInfo, &cieInfo);
1569       foundInCache = foundFDE;
1570     }
1571   }
1572   if (!foundFDE) {
1573     // Still not found, do full scan of __eh_frame section.
1574     foundFDE = CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
1575                                       sects.dwarf_section_length, 0,
1576                                       &fdeInfo, &cieInfo);
1577   }
1578   if (foundFDE) {
1579     if (getInfoFromFdeCie(fdeInfo, cieInfo, pc, sects.dso_base)) {
1580       // Add to cache (to make next lookup faster) if we had no hint
1581       // and there was no index.
1582       if (!foundInCache && (fdeSectionOffsetHint == 0)) {
1583   #if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
1584         if (sects.dwarf_index_section == 0)
1585   #endif
1586         DwarfFDECache<A>::add(sects.dso_base, fdeInfo.pcStart, fdeInfo.pcEnd,
1587                               fdeInfo.fdeStart);
1588       }
1589       return true;
1590     }
1591   }
1592   //_LIBUNWIND_DEBUG_LOG("can't find/use FDE for pc=0x%llX", (uint64_t)pc);
1593   return false;
1594 }
1595 #endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1596 
1597 
1598 #if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1599 template <typename A, typename R>
1600 bool UnwindCursor<A, R>::getInfoFromCompactEncodingSection(pint_t pc,
1601                                               const UnwindInfoSections &sects) {
1602   const bool log = false;
1603   if (log)
1604     fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX, mh=0x%llX)\n",
1605             (uint64_t)pc, (uint64_t)sects.dso_base);
1606 
1607   const UnwindSectionHeader<A> sectionHeader(_addressSpace,
1608                                                 sects.compact_unwind_section);
1609   if (sectionHeader.version() != UNWIND_SECTION_VERSION)
1610     return false;
1611 
1612   // do a binary search of top level index to find page with unwind info
1613   pint_t targetFunctionOffset = pc - sects.dso_base;
1614   const UnwindSectionIndexArray<A> topIndex(_addressSpace,
1615                                            sects.compact_unwind_section
1616                                          + sectionHeader.indexSectionOffset());
1617   uint32_t low = 0;
1618   uint32_t high = sectionHeader.indexCount();
1619   uint32_t last = high - 1;
1620   while (low < high) {
1621     uint32_t mid = (low + high) / 2;
1622     //if ( log ) fprintf(stderr, "\tmid=%d, low=%d, high=%d, *mid=0x%08X\n",
1623     //mid, low, high, topIndex.functionOffset(mid));
1624     if (topIndex.functionOffset(mid) <= targetFunctionOffset) {
1625       if ((mid == last) ||
1626           (topIndex.functionOffset(mid + 1) > targetFunctionOffset)) {
1627         low = mid;
1628         break;
1629       } else {
1630         low = mid + 1;
1631       }
1632     } else {
1633       high = mid;
1634     }
1635   }
1636   const uint32_t firstLevelFunctionOffset = topIndex.functionOffset(low);
1637   const uint32_t firstLevelNextPageFunctionOffset =
1638       topIndex.functionOffset(low + 1);
1639   const pint_t secondLevelAddr =
1640       sects.compact_unwind_section + topIndex.secondLevelPagesSectionOffset(low);
1641   const pint_t lsdaArrayStartAddr =
1642       sects.compact_unwind_section + topIndex.lsdaIndexArraySectionOffset(low);
1643   const pint_t lsdaArrayEndAddr =
1644       sects.compact_unwind_section + topIndex.lsdaIndexArraySectionOffset(low+1);
1645   if (log)
1646     fprintf(stderr, "\tfirst level search for result index=%d "
1647                     "to secondLevelAddr=0x%llX\n",
1648                     low, (uint64_t) secondLevelAddr);
1649   // do a binary search of second level page index
1650   uint32_t encoding = 0;
1651   pint_t funcStart = 0;
1652   pint_t funcEnd = 0;
1653   pint_t lsda = 0;
1654   pint_t personality = 0;
1655   uint32_t pageKind = _addressSpace.get32(secondLevelAddr);
1656   if (pageKind == UNWIND_SECOND_LEVEL_REGULAR) {
1657     // regular page
1658     UnwindSectionRegularPageHeader<A> pageHeader(_addressSpace,
1659                                                  secondLevelAddr);
1660     UnwindSectionRegularArray<A> pageIndex(
1661         _addressSpace, secondLevelAddr + pageHeader.entryPageOffset());
1662     // binary search looks for entry with e where index[e].offset <= pc <
1663     // index[e+1].offset
1664     if (log)
1665       fprintf(stderr, "\tbinary search for targetFunctionOffset=0x%08llX in "
1666                       "regular page starting at secondLevelAddr=0x%llX\n",
1667               (uint64_t) targetFunctionOffset, (uint64_t) secondLevelAddr);
1668     low = 0;
1669     high = pageHeader.entryCount();
1670     while (low < high) {
1671       uint32_t mid = (low + high) / 2;
1672       if (pageIndex.functionOffset(mid) <= targetFunctionOffset) {
1673         if (mid == (uint32_t)(pageHeader.entryCount() - 1)) {
1674           // at end of table
1675           low = mid;
1676           funcEnd = firstLevelNextPageFunctionOffset + sects.dso_base;
1677           break;
1678         } else if (pageIndex.functionOffset(mid + 1) > targetFunctionOffset) {
1679           // next is too big, so we found it
1680           low = mid;
1681           funcEnd = pageIndex.functionOffset(low + 1) + sects.dso_base;
1682           break;
1683         } else {
1684           low = mid + 1;
1685         }
1686       } else {
1687         high = mid;
1688       }
1689     }
1690     encoding = pageIndex.encoding(low);
1691     funcStart = pageIndex.functionOffset(low) + sects.dso_base;
1692     if (pc < funcStart) {
1693       if (log)
1694         fprintf(
1695             stderr,
1696             "\tpc not in table, pc=0x%llX, funcStart=0x%llX, funcEnd=0x%llX\n",
1697             (uint64_t) pc, (uint64_t) funcStart, (uint64_t) funcEnd);
1698       return false;
1699     }
1700     if (pc > funcEnd) {
1701       if (log)
1702         fprintf(
1703             stderr,
1704             "\tpc not in table, pc=0x%llX, funcStart=0x%llX, funcEnd=0x%llX\n",
1705             (uint64_t) pc, (uint64_t) funcStart, (uint64_t) funcEnd);
1706       return false;
1707     }
1708   } else if (pageKind == UNWIND_SECOND_LEVEL_COMPRESSED) {
1709     // compressed page
1710     UnwindSectionCompressedPageHeader<A> pageHeader(_addressSpace,
1711                                                     secondLevelAddr);
1712     UnwindSectionCompressedArray<A> pageIndex(
1713         _addressSpace, secondLevelAddr + pageHeader.entryPageOffset());
1714     const uint32_t targetFunctionPageOffset =
1715         (uint32_t)(targetFunctionOffset - firstLevelFunctionOffset);
1716     // binary search looks for entry with e where index[e].offset <= pc <
1717     // index[e+1].offset
1718     if (log)
1719       fprintf(stderr, "\tbinary search of compressed page starting at "
1720                       "secondLevelAddr=0x%llX\n",
1721               (uint64_t) secondLevelAddr);
1722     low = 0;
1723     last = pageHeader.entryCount() - 1;
1724     high = pageHeader.entryCount();
1725     while (low < high) {
1726       uint32_t mid = (low + high) / 2;
1727       if (pageIndex.functionOffset(mid) <= targetFunctionPageOffset) {
1728         if ((mid == last) ||
1729             (pageIndex.functionOffset(mid + 1) > targetFunctionPageOffset)) {
1730           low = mid;
1731           break;
1732         } else {
1733           low = mid + 1;
1734         }
1735       } else {
1736         high = mid;
1737       }
1738     }
1739     funcStart = pageIndex.functionOffset(low) + firstLevelFunctionOffset
1740                                                               + sects.dso_base;
1741     if (low < last)
1742       funcEnd =
1743           pageIndex.functionOffset(low + 1) + firstLevelFunctionOffset
1744                                                               + sects.dso_base;
1745     else
1746       funcEnd = firstLevelNextPageFunctionOffset + sects.dso_base;
1747     if (pc < funcStart) {
1748       _LIBUNWIND_DEBUG_LOG("malformed __unwind_info, pc=0x%llX "
1749                            "not in second level compressed unwind table. "
1750                            "funcStart=0x%llX",
1751                             (uint64_t) pc, (uint64_t) funcStart);
1752       return false;
1753     }
1754     if (pc > funcEnd) {
1755       _LIBUNWIND_DEBUG_LOG("malformed __unwind_info, pc=0x%llX "
1756                            "not in second level compressed unwind table. "
1757                            "funcEnd=0x%llX",
1758                            (uint64_t) pc, (uint64_t) funcEnd);
1759       return false;
1760     }
1761     uint16_t encodingIndex = pageIndex.encodingIndex(low);
1762     if (encodingIndex < sectionHeader.commonEncodingsArrayCount()) {
1763       // encoding is in common table in section header
1764       encoding = _addressSpace.get32(
1765           sects.compact_unwind_section +
1766           sectionHeader.commonEncodingsArraySectionOffset() +
1767           encodingIndex * sizeof(uint32_t));
1768     } else {
1769       // encoding is in page specific table
1770       uint16_t pageEncodingIndex =
1771           encodingIndex - (uint16_t)sectionHeader.commonEncodingsArrayCount();
1772       encoding = _addressSpace.get32(secondLevelAddr +
1773                                      pageHeader.encodingsPageOffset() +
1774                                      pageEncodingIndex * sizeof(uint32_t));
1775     }
1776   } else {
1777     _LIBUNWIND_DEBUG_LOG(
1778         "malformed __unwind_info at 0x%0llX bad second level page",
1779         (uint64_t)sects.compact_unwind_section);
1780     return false;
1781   }
1782 
1783   // look up LSDA, if encoding says function has one
1784   if (encoding & UNWIND_HAS_LSDA) {
1785     UnwindSectionLsdaArray<A> lsdaIndex(_addressSpace, lsdaArrayStartAddr);
1786     uint32_t funcStartOffset = (uint32_t)(funcStart - sects.dso_base);
1787     low = 0;
1788     high = (uint32_t)(lsdaArrayEndAddr - lsdaArrayStartAddr) /
1789                     sizeof(unwind_info_section_header_lsda_index_entry);
1790     // binary search looks for entry with exact match for functionOffset
1791     if (log)
1792       fprintf(stderr,
1793               "\tbinary search of lsda table for targetFunctionOffset=0x%08X\n",
1794               funcStartOffset);
1795     while (low < high) {
1796       uint32_t mid = (low + high) / 2;
1797       if (lsdaIndex.functionOffset(mid) == funcStartOffset) {
1798         lsda = lsdaIndex.lsdaOffset(mid) + sects.dso_base;
1799         break;
1800       } else if (lsdaIndex.functionOffset(mid) < funcStartOffset) {
1801         low = mid + 1;
1802       } else {
1803         high = mid;
1804       }
1805     }
1806     if (lsda == 0) {
1807       _LIBUNWIND_DEBUG_LOG("found encoding 0x%08X with HAS_LSDA bit set for "
1808                     "pc=0x%0llX, but lsda table has no entry",
1809                     encoding, (uint64_t) pc);
1810       return false;
1811     }
1812   }
1813 
1814   // extract personality routine, if encoding says function has one
1815   uint32_t personalityIndex = (encoding & UNWIND_PERSONALITY_MASK) >>
1816                               (__builtin_ctz(UNWIND_PERSONALITY_MASK));
1817   if (personalityIndex != 0) {
1818     --personalityIndex; // change 1-based to zero-based index
1819     if (personalityIndex >= sectionHeader.personalityArrayCount()) {
1820       _LIBUNWIND_DEBUG_LOG("found encoding 0x%08X with personality index %d,  "
1821                             "but personality table has only %d entries",
1822                             encoding, personalityIndex,
1823                             sectionHeader.personalityArrayCount());
1824       return false;
1825     }
1826     int32_t personalityDelta = (int32_t)_addressSpace.get32(
1827         sects.compact_unwind_section +
1828         sectionHeader.personalityArraySectionOffset() +
1829         personalityIndex * sizeof(uint32_t));
1830     pint_t personalityPointer = sects.dso_base + (pint_t)personalityDelta;
1831     personality = _addressSpace.getP(personalityPointer);
1832     if (log)
1833       fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX), "
1834                       "personalityDelta=0x%08X, personality=0x%08llX\n",
1835               (uint64_t) pc, personalityDelta, (uint64_t) personality);
1836   }
1837 
1838   if (log)
1839     fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX), "
1840                     "encoding=0x%08X, lsda=0x%08llX for funcStart=0x%llX\n",
1841             (uint64_t) pc, encoding, (uint64_t) lsda, (uint64_t) funcStart);
1842   _info.start_ip = funcStart;
1843   _info.end_ip = funcEnd;
1844   _info.lsda = lsda;
1845   _info.handler = personality;
1846   _info.gp = 0;
1847   _info.flags = 0;
1848   _info.format = encoding;
1849   _info.unwind_info = 0;
1850   _info.unwind_info_size = 0;
1851   _info.extra = sects.dso_base;
1852   return true;
1853 }
1854 #endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1855 
1856 
1857 #if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1858 template <typename A, typename R>
1859 bool UnwindCursor<A, R>::getInfoFromSEH(pint_t pc) {
1860   pint_t base;
1861   RUNTIME_FUNCTION *unwindEntry = lookUpSEHUnwindInfo(pc, &base);
1862   if (!unwindEntry) {
1863     _LIBUNWIND_DEBUG_LOG("\tpc not in table, pc=0x%llX", (uint64_t) pc);
1864     return false;
1865   }
1866   _info.gp = 0;
1867   _info.flags = 0;
1868   _info.format = 0;
1869   _info.unwind_info_size = sizeof(RUNTIME_FUNCTION);
1870   _info.unwind_info = reinterpret_cast<unw_word_t>(unwindEntry);
1871   _info.extra = base;
1872   _info.start_ip = base + unwindEntry->BeginAddress;
1873 #ifdef _LIBUNWIND_TARGET_X86_64
1874   _info.end_ip = base + unwindEntry->EndAddress;
1875   // Only fill in the handler and LSDA if they're stale.
1876   if (pc != getLastPC()) {
1877     UNWIND_INFO *xdata = reinterpret_cast<UNWIND_INFO *>(base + unwindEntry->UnwindData);
1878     if (xdata->Flags & (UNW_FLAG_EHANDLER|UNW_FLAG_UHANDLER)) {
1879       // The personality is given in the UNWIND_INFO itself. The LSDA immediately
1880       // follows the UNWIND_INFO. (This follows how both Clang and MSVC emit
1881       // these structures.)
1882       // N.B. UNWIND_INFO structs are DWORD-aligned.
1883       uint32_t lastcode = (xdata->CountOfCodes + 1) & ~1;
1884       const uint32_t *handler = reinterpret_cast<uint32_t *>(&xdata->UnwindCodes[lastcode]);
1885       _info.lsda = reinterpret_cast<unw_word_t>(handler+1);
1886       if (*handler) {
1887         _info.handler = reinterpret_cast<unw_word_t>(__libunwind_seh_personality);
1888       } else
1889         _info.handler = 0;
1890     } else {
1891       _info.lsda = 0;
1892       _info.handler = 0;
1893     }
1894   }
1895 #elif defined(_LIBUNWIND_TARGET_ARM)
1896   _info.end_ip = _info.start_ip + unwindEntry->FunctionLength;
1897   _info.lsda = 0; // FIXME
1898   _info.handler = 0; // FIXME
1899 #endif
1900   setLastPC(pc);
1901   return true;
1902 }
1903 #endif
1904 
1905 
1906 template <typename A, typename R>
1907 void UnwindCursor<A, R>::setInfoBasedOnIPRegister(bool isReturnAddress) {
1908 #if defined(_LIBUNWIND_TARGET_LINUX) && defined(_LIBUNWIND_TARGET_AARCH64)
1909   _isSigReturn = false;
1910 #endif
1911 
1912   pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
1913 #if defined(_LIBUNWIND_ARM_EHABI)
1914   // Remove the thumb bit so the IP represents the actual instruction address.
1915   // This matches the behaviour of _Unwind_GetIP on arm.
1916   pc &= (pint_t)~0x1;
1917 #endif
1918 
1919   // Exit early if at the top of the stack.
1920   if (pc == 0) {
1921     _unwindInfoMissing = true;
1922     return;
1923   }
1924 
1925   // If the last line of a function is a "throw" the compiler sometimes
1926   // emits no instructions after the call to __cxa_throw.  This means
1927   // the return address is actually the start of the next function.
1928   // To disambiguate this, back up the pc when we know it is a return
1929   // address.
1930   if (isReturnAddress)
1931     --pc;
1932 
1933   // Ask address space object to find unwind sections for this pc.
1934   UnwindInfoSections sects;
1935   bool have_sects = false;
1936   if (uwis_cache.getUnwindInfoSectionsForPC(pc, sects))
1937     have_sects = true;
1938   else if (_addressSpace.findUnwindSections(pc, sects)) {
1939     uwis_cache.setUnwindInfoSectionsForPC(pc, sects);
1940     have_sects = true;
1941   }
1942   if (have_sects) {
1943 #if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1944     // If there is a compact unwind encoding table, look there first.
1945     if (sects.compact_unwind_section != 0) {
1946       if (this->getInfoFromCompactEncodingSection(pc, sects)) {
1947   #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1948         // Found info in table, done unless encoding says to use dwarf.
1949         uint32_t dwarfOffset;
1950         if ((sects.dwarf_section != 0) && compactSaysUseDwarf(&dwarfOffset)) {
1951           if (this->getInfoFromDwarfSection(pc, sects, dwarfOffset)) {
1952             // found info in dwarf, done
1953             return;
1954           }
1955         }
1956   #endif
1957         // If unwind table has entry, but entry says there is no unwind info,
1958         // record that we have no unwind info.
1959         if (_info.format == 0)
1960           _unwindInfoMissing = true;
1961         return;
1962       }
1963     }
1964 #endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1965 
1966 #if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1967     // If there is SEH unwind info, look there next.
1968     if (this->getInfoFromSEH(pc))
1969       return;
1970 #endif
1971 
1972 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1973     // If there is dwarf unwind info, look there next.
1974     if (sects.dwarf_section != 0) {
1975       if (this->getInfoFromDwarfSection(pc, sects)) {
1976         // found info in dwarf, done
1977         return;
1978       }
1979     }
1980 #endif
1981 
1982 #if defined(_LIBUNWIND_ARM_EHABI)
1983     // If there is ARM EHABI unwind info, look there next.
1984     if (sects.arm_section != 0 && this->getInfoFromEHABISection(pc, sects))
1985       return;
1986 #endif
1987   }
1988 
1989 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1990   // There is no static unwind info for this pc. Look to see if an FDE was
1991   // dynamically registered for it.
1992   pint_t cachedFDE = DwarfFDECache<A>::findFDE(DwarfFDECache<A>::kSearchAll,
1993                                                pc);
1994   if (cachedFDE != 0) {
1995     typename CFI_Parser<A>::FDE_Info fdeInfo;
1996     typename CFI_Parser<A>::CIE_Info cieInfo;
1997     if (!CFI_Parser<A>::decodeFDE(_addressSpace, cachedFDE, &fdeInfo, &cieInfo))
1998       if (getInfoFromFdeCie(fdeInfo, cieInfo, pc, 0))
1999         return;
2000   }
2001 
2002   // Lastly, ask AddressSpace object about platform specific ways to locate
2003   // other FDEs.
2004   pint_t fde;
2005   if (_addressSpace.findOtherFDE(pc, fde)) {
2006     typename CFI_Parser<A>::FDE_Info fdeInfo;
2007     typename CFI_Parser<A>::CIE_Info cieInfo;
2008     if (!CFI_Parser<A>::decodeFDE(_addressSpace, fde, &fdeInfo, &cieInfo)) {
2009       // Double check this FDE is for a function that includes the pc.
2010       if ((fdeInfo.pcStart <= pc) && (pc < fdeInfo.pcEnd))
2011         if (getInfoFromFdeCie(fdeInfo, cieInfo, pc, 0))
2012           return;
2013     }
2014   }
2015 #endif // #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
2016 
2017 #if defined(_LIBUNWIND_TARGET_LINUX) && defined(_LIBUNWIND_TARGET_AARCH64)
2018   if (setInfoForSigReturn())
2019     return;
2020 #endif
2021 
2022   // no unwind info, flag that we can't reliably unwind
2023   _unwindInfoMissing = true;
2024 }
2025 
2026 #if defined(_LIBUNWIND_TARGET_LINUX) && defined(_LIBUNWIND_TARGET_AARCH64)
2027 template <typename A, typename R>
2028 bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_arm64 &) {
2029   // Look for the sigreturn trampoline. The trampoline's body is two
2030   // specific instructions (see below). Typically the trampoline comes from the
2031   // vDSO[1] (i.e. the __kernel_rt_sigreturn function). A libc might provide its
2032   // own restorer function, though, or user-mode QEMU might write a trampoline
2033   // onto the stack.
2034   //
2035   // This special code path is a fallback that is only used if the trampoline
2036   // lacks proper (e.g. DWARF) unwind info. On AArch64, a new DWARF register
2037   // constant for the PC needs to be defined before DWARF can handle a signal
2038   // trampoline. This code may segfault if the target PC is unreadable, e.g.:
2039   //  - The PC points at a function compiled without unwind info, and which is
2040   //    part of an execute-only mapping (e.g. using -Wl,--execute-only).
2041   //  - The PC is invalid and happens to point to unreadable or unmapped memory.
2042   //
2043   // [1] https://github.com/torvalds/linux/blob/master/arch/arm64/kernel/vdso/sigreturn.S
2044   const pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
2045   // Look for instructions: mov x8, #0x8b; svc #0x0
2046   if (_addressSpace.get32(pc) == 0xd2801168 &&
2047       _addressSpace.get32(pc + 4) == 0xd4000001) {
2048     _info = {};
2049     _isSigReturn = true;
2050     return true;
2051   }
2052   return false;
2053 }
2054 
2055 template <typename A, typename R>
2056 int UnwindCursor<A, R>::stepThroughSigReturn(Registers_arm64 &) {
2057   // In the signal trampoline frame, sp points to an rt_sigframe[1], which is:
2058   //  - 128-byte siginfo struct
2059   //  - ucontext struct:
2060   //     - 8-byte long (uc_flags)
2061   //     - 8-byte pointer (uc_link)
2062   //     - 24-byte stack_t
2063   //     - 128-byte signal set
2064   //     - 8 bytes of padding because sigcontext has 16-byte alignment
2065   //     - sigcontext/mcontext_t
2066   // [1] https://github.com/torvalds/linux/blob/master/arch/arm64/kernel/signal.c
2067   const pint_t kOffsetSpToSigcontext = (128 + 8 + 8 + 24 + 128 + 8); // 304
2068 
2069   // Offsets from sigcontext to each register.
2070   const pint_t kOffsetGprs = 8; // offset to "__u64 regs[31]" field
2071   const pint_t kOffsetSp = 256; // offset to "__u64 sp" field
2072   const pint_t kOffsetPc = 264; // offset to "__u64 pc" field
2073 
2074   pint_t sigctx = _registers.getSP() + kOffsetSpToSigcontext;
2075 
2076   for (int i = 0; i <= 30; ++i) {
2077     uint64_t value = _addressSpace.get64(sigctx + kOffsetGprs +
2078                                          static_cast<pint_t>(i * 8));
2079     _registers.setRegister(UNW_ARM64_X0 + i, value);
2080   }
2081   _registers.setSP(_addressSpace.get64(sigctx + kOffsetSp));
2082   _registers.setIP(_addressSpace.get64(sigctx + kOffsetPc));
2083   _isSignalFrame = true;
2084   return UNW_STEP_SUCCESS;
2085 }
2086 #endif // defined(_LIBUNWIND_TARGET_LINUX) && defined(_LIBUNWIND_TARGET_AARCH64)
2087 
2088 template <typename A, typename R>
2089 int UnwindCursor<A, R>::step() {
2090   // Bottom of stack is defined is when unwind info cannot be found.
2091   if (_unwindInfoMissing)
2092     return UNW_STEP_END;
2093 
2094   // Use unwinding info to modify register set as if function returned.
2095   int result;
2096 #if defined(_LIBUNWIND_TARGET_LINUX) && defined(_LIBUNWIND_TARGET_AARCH64)
2097   if (_isSigReturn) {
2098     result = this->stepThroughSigReturn();
2099   } else
2100 #endif
2101   {
2102 #if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
2103     result = this->stepWithCompactEncoding();
2104 #elif defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
2105     result = this->stepWithSEHData();
2106 #elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
2107     result = this->stepWithDwarfFDE();
2108 #elif defined(_LIBUNWIND_ARM_EHABI)
2109     result = this->stepWithEHABI();
2110 #else
2111   #error Need _LIBUNWIND_SUPPORT_COMPACT_UNWIND or \
2112               _LIBUNWIND_SUPPORT_SEH_UNWIND or \
2113               _LIBUNWIND_SUPPORT_DWARF_UNWIND or \
2114               _LIBUNWIND_ARM_EHABI
2115 #endif
2116   }
2117 
2118   // update info based on new PC
2119   if (result == UNW_STEP_SUCCESS) {
2120     this->setInfoBasedOnIPRegister(true);
2121     if (_unwindInfoMissing)
2122       return UNW_STEP_END;
2123   }
2124 
2125   return result;
2126 }
2127 
2128 template <typename A, typename R>
2129 void UnwindCursor<A, R>::getInfo(unw_proc_info_t *info) {
2130   if (_unwindInfoMissing)
2131     memset(info, 0, sizeof(*info));
2132   else
2133     *info = _info;
2134 }
2135 
2136 template <typename A, typename R>
2137 bool UnwindCursor<A, R>::getFunctionName(char *buf, size_t bufLen,
2138                                                            unw_word_t *offset) {
2139   return _addressSpace.findFunctionName((pint_t)this->getReg(UNW_REG_IP),
2140                                          buf, bufLen, offset);
2141 }
2142 
2143 } // namespace libunwind
2144 
2145 #endif // __UNWINDCURSOR_HPP__
2146