xref: /freebsd/contrib/llvm-project/libunwind/src/UnwindCursor.hpp (revision cfd6422a5217410fbd66f7a7a8a64d9d85e61229)
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 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
79 /// Cache of recently found FDEs.
80 template <typename A>
81 class _LIBUNWIND_HIDDEN DwarfFDECache {
82   typedef typename A::pint_t pint_t;
83 public:
84   static pint_t findFDE(pint_t mh, pint_t pc);
85   static void add(pint_t mh, pint_t ip_start, pint_t ip_end, pint_t fde);
86   static void removeAllIn(pint_t mh);
87   static void iterateCacheEntries(void (*func)(unw_word_t ip_start,
88                                                unw_word_t ip_end,
89                                                unw_word_t fde, unw_word_t mh));
90 
91 private:
92 
93   struct entry {
94     pint_t mh;
95     pint_t ip_start;
96     pint_t ip_end;
97     pint_t fde;
98   };
99 
100   // These fields are all static to avoid needing an initializer.
101   // There is only one instance of this class per process.
102   static RWMutex _lock;
103 #ifdef __APPLE__
104   static void dyldUnloadHook(const struct mach_header *mh, intptr_t slide);
105   static bool _registeredForDyldUnloads;
106 #endif
107   static entry *_buffer;
108   static entry *_bufferUsed;
109   static entry *_bufferEnd;
110   static entry _initialBuffer[64];
111 };
112 
113 template <typename A>
114 typename DwarfFDECache<A>::entry *
115 DwarfFDECache<A>::_buffer = _initialBuffer;
116 
117 template <typename A>
118 typename DwarfFDECache<A>::entry *
119 DwarfFDECache<A>::_bufferUsed = _initialBuffer;
120 
121 template <typename A>
122 typename DwarfFDECache<A>::entry *
123 DwarfFDECache<A>::_bufferEnd = &_initialBuffer[64];
124 
125 template <typename A>
126 typename DwarfFDECache<A>::entry DwarfFDECache<A>::_initialBuffer[64];
127 
128 template <typename A>
129 RWMutex DwarfFDECache<A>::_lock;
130 
131 #ifdef __APPLE__
132 template <typename A>
133 bool DwarfFDECache<A>::_registeredForDyldUnloads = false;
134 #endif
135 
136 template <typename A>
137 typename A::pint_t DwarfFDECache<A>::findFDE(pint_t mh, pint_t pc) {
138   pint_t result = 0;
139   _LIBUNWIND_LOG_IF_FALSE(_lock.lock_shared());
140   for (entry *p = _buffer; p < _bufferUsed; ++p) {
141     if ((mh == p->mh) || (mh == 0)) {
142       if ((p->ip_start <= pc) && (pc < p->ip_end)) {
143         result = p->fde;
144         break;
145       }
146     }
147   }
148   _LIBUNWIND_LOG_IF_FALSE(_lock.unlock_shared());
149   return result;
150 }
151 
152 template <typename A>
153 void DwarfFDECache<A>::add(pint_t mh, pint_t ip_start, pint_t ip_end,
154                            pint_t fde) {
155 #if !defined(_LIBUNWIND_NO_HEAP)
156   _LIBUNWIND_LOG_IF_FALSE(_lock.lock());
157   if (_bufferUsed >= _bufferEnd) {
158     size_t oldSize = (size_t)(_bufferEnd - _buffer);
159     size_t newSize = oldSize * 4;
160     // Can't use operator new (we are below it).
161     entry *newBuffer = (entry *)malloc(newSize * sizeof(entry));
162     memcpy(newBuffer, _buffer, oldSize * sizeof(entry));
163     if (_buffer != _initialBuffer)
164       free(_buffer);
165     _buffer = newBuffer;
166     _bufferUsed = &newBuffer[oldSize];
167     _bufferEnd = &newBuffer[newSize];
168   }
169   _bufferUsed->mh = mh;
170   _bufferUsed->ip_start = ip_start;
171   _bufferUsed->ip_end = ip_end;
172   _bufferUsed->fde = fde;
173   ++_bufferUsed;
174 #ifdef __APPLE__
175   if (!_registeredForDyldUnloads) {
176     _dyld_register_func_for_remove_image(&dyldUnloadHook);
177     _registeredForDyldUnloads = true;
178   }
179 #endif
180   _LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
181 #endif
182 }
183 
184 template <typename A>
185 void DwarfFDECache<A>::removeAllIn(pint_t mh) {
186   _LIBUNWIND_LOG_IF_FALSE(_lock.lock());
187   entry *d = _buffer;
188   for (const entry *s = _buffer; s < _bufferUsed; ++s) {
189     if (s->mh != mh) {
190       if (d != s)
191         *d = *s;
192       ++d;
193     }
194   }
195   _bufferUsed = d;
196   _LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
197 }
198 
199 #ifdef __APPLE__
200 template <typename A>
201 void DwarfFDECache<A>::dyldUnloadHook(const struct mach_header *mh, intptr_t ) {
202   removeAllIn((pint_t) mh);
203 }
204 #endif
205 
206 template <typename A>
207 void DwarfFDECache<A>::iterateCacheEntries(void (*func)(
208     unw_word_t ip_start, unw_word_t ip_end, unw_word_t fde, unw_word_t mh)) {
209   _LIBUNWIND_LOG_IF_FALSE(_lock.lock());
210   for (entry *p = _buffer; p < _bufferUsed; ++p) {
211     (*func)(p->ip_start, p->ip_end, p->fde, p->mh);
212   }
213   _LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
214 }
215 #endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
216 
217 
218 #define arrayoffsetof(type, index, field) ((size_t)(&((type *)0)[index].field))
219 
220 #if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
221 template <typename A> class UnwindSectionHeader {
222 public:
223   UnwindSectionHeader(A &addressSpace, typename A::pint_t addr)
224       : _addressSpace(addressSpace), _addr(addr) {}
225 
226   uint32_t version() const {
227     return _addressSpace.get32(_addr +
228                                offsetof(unwind_info_section_header, version));
229   }
230   uint32_t commonEncodingsArraySectionOffset() const {
231     return _addressSpace.get32(_addr +
232                                offsetof(unwind_info_section_header,
233                                         commonEncodingsArraySectionOffset));
234   }
235   uint32_t commonEncodingsArrayCount() const {
236     return _addressSpace.get32(_addr + offsetof(unwind_info_section_header,
237                                                 commonEncodingsArrayCount));
238   }
239   uint32_t personalityArraySectionOffset() const {
240     return _addressSpace.get32(_addr + offsetof(unwind_info_section_header,
241                                                 personalityArraySectionOffset));
242   }
243   uint32_t personalityArrayCount() const {
244     return _addressSpace.get32(
245         _addr + offsetof(unwind_info_section_header, personalityArrayCount));
246   }
247   uint32_t indexSectionOffset() const {
248     return _addressSpace.get32(
249         _addr + offsetof(unwind_info_section_header, indexSectionOffset));
250   }
251   uint32_t indexCount() const {
252     return _addressSpace.get32(
253         _addr + offsetof(unwind_info_section_header, indexCount));
254   }
255 
256 private:
257   A                     &_addressSpace;
258   typename A::pint_t     _addr;
259 };
260 
261 template <typename A> class UnwindSectionIndexArray {
262 public:
263   UnwindSectionIndexArray(A &addressSpace, typename A::pint_t addr)
264       : _addressSpace(addressSpace), _addr(addr) {}
265 
266   uint32_t functionOffset(uint32_t index) const {
267     return _addressSpace.get32(
268         _addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
269                               functionOffset));
270   }
271   uint32_t secondLevelPagesSectionOffset(uint32_t index) const {
272     return _addressSpace.get32(
273         _addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
274                               secondLevelPagesSectionOffset));
275   }
276   uint32_t lsdaIndexArraySectionOffset(uint32_t index) const {
277     return _addressSpace.get32(
278         _addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
279                               lsdaIndexArraySectionOffset));
280   }
281 
282 private:
283   A                   &_addressSpace;
284   typename A::pint_t   _addr;
285 };
286 
287 template <typename A> class UnwindSectionRegularPageHeader {
288 public:
289   UnwindSectionRegularPageHeader(A &addressSpace, typename A::pint_t addr)
290       : _addressSpace(addressSpace), _addr(addr) {}
291 
292   uint32_t kind() const {
293     return _addressSpace.get32(
294         _addr + offsetof(unwind_info_regular_second_level_page_header, kind));
295   }
296   uint16_t entryPageOffset() const {
297     return _addressSpace.get16(
298         _addr + offsetof(unwind_info_regular_second_level_page_header,
299                          entryPageOffset));
300   }
301   uint16_t entryCount() const {
302     return _addressSpace.get16(
303         _addr +
304         offsetof(unwind_info_regular_second_level_page_header, entryCount));
305   }
306 
307 private:
308   A &_addressSpace;
309   typename A::pint_t _addr;
310 };
311 
312 template <typename A> class UnwindSectionRegularArray {
313 public:
314   UnwindSectionRegularArray(A &addressSpace, typename A::pint_t addr)
315       : _addressSpace(addressSpace), _addr(addr) {}
316 
317   uint32_t functionOffset(uint32_t index) const {
318     return _addressSpace.get32(
319         _addr + arrayoffsetof(unwind_info_regular_second_level_entry, index,
320                               functionOffset));
321   }
322   uint32_t encoding(uint32_t index) const {
323     return _addressSpace.get32(
324         _addr +
325         arrayoffsetof(unwind_info_regular_second_level_entry, index, encoding));
326   }
327 
328 private:
329   A &_addressSpace;
330   typename A::pint_t _addr;
331 };
332 
333 template <typename A> class UnwindSectionCompressedPageHeader {
334 public:
335   UnwindSectionCompressedPageHeader(A &addressSpace, typename A::pint_t addr)
336       : _addressSpace(addressSpace), _addr(addr) {}
337 
338   uint32_t kind() const {
339     return _addressSpace.get32(
340         _addr +
341         offsetof(unwind_info_compressed_second_level_page_header, kind));
342   }
343   uint16_t entryPageOffset() const {
344     return _addressSpace.get16(
345         _addr + offsetof(unwind_info_compressed_second_level_page_header,
346                          entryPageOffset));
347   }
348   uint16_t entryCount() const {
349     return _addressSpace.get16(
350         _addr +
351         offsetof(unwind_info_compressed_second_level_page_header, entryCount));
352   }
353   uint16_t encodingsPageOffset() const {
354     return _addressSpace.get16(
355         _addr + offsetof(unwind_info_compressed_second_level_page_header,
356                          encodingsPageOffset));
357   }
358   uint16_t encodingsCount() const {
359     return _addressSpace.get16(
360         _addr + offsetof(unwind_info_compressed_second_level_page_header,
361                          encodingsCount));
362   }
363 
364 private:
365   A &_addressSpace;
366   typename A::pint_t _addr;
367 };
368 
369 template <typename A> class UnwindSectionCompressedArray {
370 public:
371   UnwindSectionCompressedArray(A &addressSpace, typename A::pint_t addr)
372       : _addressSpace(addressSpace), _addr(addr) {}
373 
374   uint32_t functionOffset(uint32_t index) const {
375     return UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET(
376         _addressSpace.get32(_addr + index * sizeof(uint32_t)));
377   }
378   uint16_t encodingIndex(uint32_t index) const {
379     return UNWIND_INFO_COMPRESSED_ENTRY_ENCODING_INDEX(
380         _addressSpace.get32(_addr + index * sizeof(uint32_t)));
381   }
382 
383 private:
384   A &_addressSpace;
385   typename A::pint_t _addr;
386 };
387 
388 template <typename A> class UnwindSectionLsdaArray {
389 public:
390   UnwindSectionLsdaArray(A &addressSpace, typename A::pint_t addr)
391       : _addressSpace(addressSpace), _addr(addr) {}
392 
393   uint32_t functionOffset(uint32_t index) const {
394     return _addressSpace.get32(
395         _addr + arrayoffsetof(unwind_info_section_header_lsda_index_entry,
396                               index, functionOffset));
397   }
398   uint32_t lsdaOffset(uint32_t index) const {
399     return _addressSpace.get32(
400         _addr + arrayoffsetof(unwind_info_section_header_lsda_index_entry,
401                               index, lsdaOffset));
402   }
403 
404 private:
405   A                   &_addressSpace;
406   typename A::pint_t   _addr;
407 };
408 #endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
409 
410 class _LIBUNWIND_HIDDEN AbstractUnwindCursor {
411 public:
412   // NOTE: provide a class specific placement deallocation function (S5.3.4 p20)
413   // This avoids an unnecessary dependency to libc++abi.
414   void operator delete(void *, size_t) {}
415 
416   virtual ~AbstractUnwindCursor() {}
417   virtual bool validReg(int) { _LIBUNWIND_ABORT("validReg not implemented"); }
418   virtual unw_word_t getReg(int) { _LIBUNWIND_ABORT("getReg not implemented"); }
419   virtual void setReg(int, unw_word_t) {
420     _LIBUNWIND_ABORT("setReg not implemented");
421   }
422   virtual bool validFloatReg(int) {
423     _LIBUNWIND_ABORT("validFloatReg not implemented");
424   }
425   virtual unw_fpreg_t getFloatReg(int) {
426     _LIBUNWIND_ABORT("getFloatReg not implemented");
427   }
428   virtual void setFloatReg(int, unw_fpreg_t) {
429     _LIBUNWIND_ABORT("setFloatReg not implemented");
430   }
431   virtual int step() { _LIBUNWIND_ABORT("step not implemented"); }
432   virtual void getInfo(unw_proc_info_t *) {
433     _LIBUNWIND_ABORT("getInfo not implemented");
434   }
435   virtual void jumpto() { _LIBUNWIND_ABORT("jumpto not implemented"); }
436   virtual bool isSignalFrame() {
437     _LIBUNWIND_ABORT("isSignalFrame not implemented");
438   }
439   virtual bool getFunctionName(char *, size_t, unw_word_t *) {
440     _LIBUNWIND_ABORT("getFunctionName not implemented");
441   }
442   virtual void setInfoBasedOnIPRegister(bool = false) {
443     _LIBUNWIND_ABORT("setInfoBasedOnIPRegister not implemented");
444   }
445   virtual const char *getRegisterName(int) {
446     _LIBUNWIND_ABORT("getRegisterName not implemented");
447   }
448 #ifdef __arm__
449   virtual void saveVFPAsX() { _LIBUNWIND_ABORT("saveVFPAsX not implemented"); }
450 #endif
451 };
452 
453 #if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) && defined(_WIN32)
454 
455 /// \c UnwindCursor contains all state (including all register values) during
456 /// an unwind.  This is normally stack-allocated inside a unw_cursor_t.
457 template <typename A, typename R>
458 class UnwindCursor : public AbstractUnwindCursor {
459   typedef typename A::pint_t pint_t;
460 public:
461                       UnwindCursor(unw_context_t *context, A &as);
462                       UnwindCursor(CONTEXT *context, A &as);
463                       UnwindCursor(A &as, void *threadArg);
464   virtual             ~UnwindCursor() {}
465   virtual bool        validReg(int);
466   virtual unw_word_t  getReg(int);
467   virtual void        setReg(int, unw_word_t);
468   virtual bool        validFloatReg(int);
469   virtual unw_fpreg_t getFloatReg(int);
470   virtual void        setFloatReg(int, unw_fpreg_t);
471   virtual int         step();
472   virtual void        getInfo(unw_proc_info_t *);
473   virtual void        jumpto();
474   virtual bool        isSignalFrame();
475   virtual bool        getFunctionName(char *buf, size_t len, unw_word_t *off);
476   virtual void        setInfoBasedOnIPRegister(bool isReturnAddress = false);
477   virtual const char *getRegisterName(int num);
478 #ifdef __arm__
479   virtual void        saveVFPAsX();
480 #endif
481 
482   DISPATCHER_CONTEXT *getDispatcherContext() { return &_dispContext; }
483   void setDispatcherContext(DISPATCHER_CONTEXT *disp) { _dispContext = *disp; }
484 
485   // libunwind does not and should not depend on C++ library which means that we
486   // need our own defition of inline placement new.
487   static void *operator new(size_t, UnwindCursor<A, R> *p) { return p; }
488 
489 private:
490 
491   pint_t getLastPC() const { return _dispContext.ControlPc; }
492   void setLastPC(pint_t pc) { _dispContext.ControlPc = pc; }
493   RUNTIME_FUNCTION *lookUpSEHUnwindInfo(pint_t pc, pint_t *base) {
494     _dispContext.FunctionEntry = RtlLookupFunctionEntry(pc,
495                                                         &_dispContext.ImageBase,
496                                                         _dispContext.HistoryTable);
497     *base = _dispContext.ImageBase;
498     return _dispContext.FunctionEntry;
499   }
500   bool getInfoFromSEH(pint_t pc);
501   int stepWithSEHData() {
502     _dispContext.LanguageHandler = RtlVirtualUnwind(UNW_FLAG_UHANDLER,
503                                                     _dispContext.ImageBase,
504                                                     _dispContext.ControlPc,
505                                                     _dispContext.FunctionEntry,
506                                                     _dispContext.ContextRecord,
507                                                     &_dispContext.HandlerData,
508                                                     &_dispContext.EstablisherFrame,
509                                                     NULL);
510     // Update some fields of the unwind info now, since we have them.
511     _info.lsda = reinterpret_cast<unw_word_t>(_dispContext.HandlerData);
512     if (_dispContext.LanguageHandler) {
513       _info.handler = reinterpret_cast<unw_word_t>(__libunwind_seh_personality);
514     } else
515       _info.handler = 0;
516     return UNW_STEP_SUCCESS;
517   }
518 
519   A                   &_addressSpace;
520   unw_proc_info_t      _info;
521   DISPATCHER_CONTEXT   _dispContext;
522   CONTEXT              _msContext;
523   UNWIND_HISTORY_TABLE _histTable;
524   bool                 _unwindInfoMissing;
525 };
526 
527 
528 template <typename A, typename R>
529 UnwindCursor<A, R>::UnwindCursor(unw_context_t *context, A &as)
530     : _addressSpace(as), _unwindInfoMissing(false) {
531   static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
532                 "UnwindCursor<> does not fit in unw_cursor_t");
533   memset(&_info, 0, sizeof(_info));
534   memset(&_histTable, 0, sizeof(_histTable));
535   _dispContext.ContextRecord = &_msContext;
536   _dispContext.HistoryTable = &_histTable;
537   // Initialize MS context from ours.
538   R r(context);
539   _msContext.ContextFlags = CONTEXT_CONTROL|CONTEXT_INTEGER|CONTEXT_FLOATING_POINT;
540 #if defined(_LIBUNWIND_TARGET_X86_64)
541   _msContext.Rax = r.getRegister(UNW_X86_64_RAX);
542   _msContext.Rcx = r.getRegister(UNW_X86_64_RCX);
543   _msContext.Rdx = r.getRegister(UNW_X86_64_RDX);
544   _msContext.Rbx = r.getRegister(UNW_X86_64_RBX);
545   _msContext.Rsp = r.getRegister(UNW_X86_64_RSP);
546   _msContext.Rbp = r.getRegister(UNW_X86_64_RBP);
547   _msContext.Rsi = r.getRegister(UNW_X86_64_RSI);
548   _msContext.Rdi = r.getRegister(UNW_X86_64_RDI);
549   _msContext.R8 = r.getRegister(UNW_X86_64_R8);
550   _msContext.R9 = r.getRegister(UNW_X86_64_R9);
551   _msContext.R10 = r.getRegister(UNW_X86_64_R10);
552   _msContext.R11 = r.getRegister(UNW_X86_64_R11);
553   _msContext.R12 = r.getRegister(UNW_X86_64_R12);
554   _msContext.R13 = r.getRegister(UNW_X86_64_R13);
555   _msContext.R14 = r.getRegister(UNW_X86_64_R14);
556   _msContext.R15 = r.getRegister(UNW_X86_64_R15);
557   _msContext.Rip = r.getRegister(UNW_REG_IP);
558   union {
559     v128 v;
560     M128A m;
561   } t;
562   t.v = r.getVectorRegister(UNW_X86_64_XMM0);
563   _msContext.Xmm0 = t.m;
564   t.v = r.getVectorRegister(UNW_X86_64_XMM1);
565   _msContext.Xmm1 = t.m;
566   t.v = r.getVectorRegister(UNW_X86_64_XMM2);
567   _msContext.Xmm2 = t.m;
568   t.v = r.getVectorRegister(UNW_X86_64_XMM3);
569   _msContext.Xmm3 = t.m;
570   t.v = r.getVectorRegister(UNW_X86_64_XMM4);
571   _msContext.Xmm4 = t.m;
572   t.v = r.getVectorRegister(UNW_X86_64_XMM5);
573   _msContext.Xmm5 = t.m;
574   t.v = r.getVectorRegister(UNW_X86_64_XMM6);
575   _msContext.Xmm6 = t.m;
576   t.v = r.getVectorRegister(UNW_X86_64_XMM7);
577   _msContext.Xmm7 = t.m;
578   t.v = r.getVectorRegister(UNW_X86_64_XMM8);
579   _msContext.Xmm8 = t.m;
580   t.v = r.getVectorRegister(UNW_X86_64_XMM9);
581   _msContext.Xmm9 = t.m;
582   t.v = r.getVectorRegister(UNW_X86_64_XMM10);
583   _msContext.Xmm10 = t.m;
584   t.v = r.getVectorRegister(UNW_X86_64_XMM11);
585   _msContext.Xmm11 = t.m;
586   t.v = r.getVectorRegister(UNW_X86_64_XMM12);
587   _msContext.Xmm12 = t.m;
588   t.v = r.getVectorRegister(UNW_X86_64_XMM13);
589   _msContext.Xmm13 = t.m;
590   t.v = r.getVectorRegister(UNW_X86_64_XMM14);
591   _msContext.Xmm14 = t.m;
592   t.v = r.getVectorRegister(UNW_X86_64_XMM15);
593   _msContext.Xmm15 = t.m;
594 #elif defined(_LIBUNWIND_TARGET_ARM)
595   _msContext.R0 = r.getRegister(UNW_ARM_R0);
596   _msContext.R1 = r.getRegister(UNW_ARM_R1);
597   _msContext.R2 = r.getRegister(UNW_ARM_R2);
598   _msContext.R3 = r.getRegister(UNW_ARM_R3);
599   _msContext.R4 = r.getRegister(UNW_ARM_R4);
600   _msContext.R5 = r.getRegister(UNW_ARM_R5);
601   _msContext.R6 = r.getRegister(UNW_ARM_R6);
602   _msContext.R7 = r.getRegister(UNW_ARM_R7);
603   _msContext.R8 = r.getRegister(UNW_ARM_R8);
604   _msContext.R9 = r.getRegister(UNW_ARM_R9);
605   _msContext.R10 = r.getRegister(UNW_ARM_R10);
606   _msContext.R11 = r.getRegister(UNW_ARM_R11);
607   _msContext.R12 = r.getRegister(UNW_ARM_R12);
608   _msContext.Sp = r.getRegister(UNW_ARM_SP);
609   _msContext.Lr = r.getRegister(UNW_ARM_LR);
610   _msContext.Pc = r.getRegister(UNW_ARM_IP);
611   for (int i = UNW_ARM_D0; i <= UNW_ARM_D31; ++i) {
612     union {
613       uint64_t w;
614       double d;
615     } d;
616     d.d = r.getFloatRegister(i);
617     _msContext.D[i - UNW_ARM_D0] = d.w;
618   }
619 #elif defined(_LIBUNWIND_TARGET_AARCH64)
620   for (int i = UNW_ARM64_X0; i <= UNW_ARM64_X30; ++i)
621     _msContext.X[i - UNW_ARM64_X0] = r.getRegister(i);
622   _msContext.Sp = r.getRegister(UNW_REG_SP);
623   _msContext.Pc = r.getRegister(UNW_REG_IP);
624   for (int i = UNW_ARM64_D0; i <= UNW_ARM64_D31; ++i)
625     _msContext.V[i - UNW_ARM64_D0].D[0] = r.getFloatRegister(i);
626 #endif
627 }
628 
629 template <typename A, typename R>
630 UnwindCursor<A, R>::UnwindCursor(CONTEXT *context, A &as)
631     : _addressSpace(as), _unwindInfoMissing(false) {
632   static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
633                 "UnwindCursor<> does not fit in unw_cursor_t");
634   memset(&_info, 0, sizeof(_info));
635   memset(&_histTable, 0, sizeof(_histTable));
636   _dispContext.ContextRecord = &_msContext;
637   _dispContext.HistoryTable = &_histTable;
638   _msContext = *context;
639 }
640 
641 
642 template <typename A, typename R>
643 bool UnwindCursor<A, R>::validReg(int regNum) {
644   if (regNum == UNW_REG_IP || regNum == UNW_REG_SP) return true;
645 #if defined(_LIBUNWIND_TARGET_X86_64)
646   if (regNum >= UNW_X86_64_RAX && regNum <= UNW_X86_64_R15) return true;
647 #elif defined(_LIBUNWIND_TARGET_ARM)
648   if (regNum >= UNW_ARM_R0 && regNum <= UNW_ARM_R15) return true;
649 #elif defined(_LIBUNWIND_TARGET_AARCH64)
650   if (regNum >= UNW_ARM64_X0 && regNum <= UNW_ARM64_X30) return true;
651 #endif
652   return false;
653 }
654 
655 template <typename A, typename R>
656 unw_word_t UnwindCursor<A, R>::getReg(int regNum) {
657   switch (regNum) {
658 #if defined(_LIBUNWIND_TARGET_X86_64)
659   case UNW_REG_IP: return _msContext.Rip;
660   case UNW_X86_64_RAX: return _msContext.Rax;
661   case UNW_X86_64_RDX: return _msContext.Rdx;
662   case UNW_X86_64_RCX: return _msContext.Rcx;
663   case UNW_X86_64_RBX: return _msContext.Rbx;
664   case UNW_REG_SP:
665   case UNW_X86_64_RSP: return _msContext.Rsp;
666   case UNW_X86_64_RBP: return _msContext.Rbp;
667   case UNW_X86_64_RSI: return _msContext.Rsi;
668   case UNW_X86_64_RDI: return _msContext.Rdi;
669   case UNW_X86_64_R8: return _msContext.R8;
670   case UNW_X86_64_R9: return _msContext.R9;
671   case UNW_X86_64_R10: return _msContext.R10;
672   case UNW_X86_64_R11: return _msContext.R11;
673   case UNW_X86_64_R12: return _msContext.R12;
674   case UNW_X86_64_R13: return _msContext.R13;
675   case UNW_X86_64_R14: return _msContext.R14;
676   case UNW_X86_64_R15: return _msContext.R15;
677 #elif defined(_LIBUNWIND_TARGET_ARM)
678   case UNW_ARM_R0: return _msContext.R0;
679   case UNW_ARM_R1: return _msContext.R1;
680   case UNW_ARM_R2: return _msContext.R2;
681   case UNW_ARM_R3: return _msContext.R3;
682   case UNW_ARM_R4: return _msContext.R4;
683   case UNW_ARM_R5: return _msContext.R5;
684   case UNW_ARM_R6: return _msContext.R6;
685   case UNW_ARM_R7: return _msContext.R7;
686   case UNW_ARM_R8: return _msContext.R8;
687   case UNW_ARM_R9: return _msContext.R9;
688   case UNW_ARM_R10: return _msContext.R10;
689   case UNW_ARM_R11: return _msContext.R11;
690   case UNW_ARM_R12: return _msContext.R12;
691   case UNW_REG_SP:
692   case UNW_ARM_SP: return _msContext.Sp;
693   case UNW_ARM_LR: return _msContext.Lr;
694   case UNW_REG_IP:
695   case UNW_ARM_IP: return _msContext.Pc;
696 #elif defined(_LIBUNWIND_TARGET_AARCH64)
697   case UNW_REG_SP: return _msContext.Sp;
698   case UNW_REG_IP: return _msContext.Pc;
699   default: return _msContext.X[regNum - UNW_ARM64_X0];
700 #endif
701   }
702   _LIBUNWIND_ABORT("unsupported register");
703 }
704 
705 template <typename A, typename R>
706 void UnwindCursor<A, R>::setReg(int regNum, unw_word_t value) {
707   switch (regNum) {
708 #if defined(_LIBUNWIND_TARGET_X86_64)
709   case UNW_REG_IP: _msContext.Rip = value; break;
710   case UNW_X86_64_RAX: _msContext.Rax = value; break;
711   case UNW_X86_64_RDX: _msContext.Rdx = value; break;
712   case UNW_X86_64_RCX: _msContext.Rcx = value; break;
713   case UNW_X86_64_RBX: _msContext.Rbx = value; break;
714   case UNW_REG_SP:
715   case UNW_X86_64_RSP: _msContext.Rsp = value; break;
716   case UNW_X86_64_RBP: _msContext.Rbp = value; break;
717   case UNW_X86_64_RSI: _msContext.Rsi = value; break;
718   case UNW_X86_64_RDI: _msContext.Rdi = value; break;
719   case UNW_X86_64_R8: _msContext.R8 = value; break;
720   case UNW_X86_64_R9: _msContext.R9 = value; break;
721   case UNW_X86_64_R10: _msContext.R10 = value; break;
722   case UNW_X86_64_R11: _msContext.R11 = value; break;
723   case UNW_X86_64_R12: _msContext.R12 = value; break;
724   case UNW_X86_64_R13: _msContext.R13 = value; break;
725   case UNW_X86_64_R14: _msContext.R14 = value; break;
726   case UNW_X86_64_R15: _msContext.R15 = value; break;
727 #elif defined(_LIBUNWIND_TARGET_ARM)
728   case UNW_ARM_R0: _msContext.R0 = value; break;
729   case UNW_ARM_R1: _msContext.R1 = value; break;
730   case UNW_ARM_R2: _msContext.R2 = value; break;
731   case UNW_ARM_R3: _msContext.R3 = value; break;
732   case UNW_ARM_R4: _msContext.R4 = value; break;
733   case UNW_ARM_R5: _msContext.R5 = value; break;
734   case UNW_ARM_R6: _msContext.R6 = value; break;
735   case UNW_ARM_R7: _msContext.R7 = value; break;
736   case UNW_ARM_R8: _msContext.R8 = value; break;
737   case UNW_ARM_R9: _msContext.R9 = value; break;
738   case UNW_ARM_R10: _msContext.R10 = value; break;
739   case UNW_ARM_R11: _msContext.R11 = value; break;
740   case UNW_ARM_R12: _msContext.R12 = value; break;
741   case UNW_REG_SP:
742   case UNW_ARM_SP: _msContext.Sp = value; break;
743   case UNW_ARM_LR: _msContext.Lr = value; break;
744   case UNW_REG_IP:
745   case UNW_ARM_IP: _msContext.Pc = value; break;
746 #elif defined(_LIBUNWIND_TARGET_AARCH64)
747   case UNW_REG_SP: _msContext.Sp = value; break;
748   case UNW_REG_IP: _msContext.Pc = value; break;
749   case UNW_ARM64_X0:
750   case UNW_ARM64_X1:
751   case UNW_ARM64_X2:
752   case UNW_ARM64_X3:
753   case UNW_ARM64_X4:
754   case UNW_ARM64_X5:
755   case UNW_ARM64_X6:
756   case UNW_ARM64_X7:
757   case UNW_ARM64_X8:
758   case UNW_ARM64_X9:
759   case UNW_ARM64_X10:
760   case UNW_ARM64_X11:
761   case UNW_ARM64_X12:
762   case UNW_ARM64_X13:
763   case UNW_ARM64_X14:
764   case UNW_ARM64_X15:
765   case UNW_ARM64_X16:
766   case UNW_ARM64_X17:
767   case UNW_ARM64_X18:
768   case UNW_ARM64_X19:
769   case UNW_ARM64_X20:
770   case UNW_ARM64_X21:
771   case UNW_ARM64_X22:
772   case UNW_ARM64_X23:
773   case UNW_ARM64_X24:
774   case UNW_ARM64_X25:
775   case UNW_ARM64_X26:
776   case UNW_ARM64_X27:
777   case UNW_ARM64_X28:
778   case UNW_ARM64_FP:
779   case UNW_ARM64_LR: _msContext.X[regNum - UNW_ARM64_X0] = value; break;
780 #endif
781   default:
782     _LIBUNWIND_ABORT("unsupported register");
783   }
784 }
785 
786 template <typename A, typename R>
787 bool UnwindCursor<A, R>::validFloatReg(int regNum) {
788 #if defined(_LIBUNWIND_TARGET_ARM)
789   if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) return true;
790   if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) return true;
791 #elif defined(_LIBUNWIND_TARGET_AARCH64)
792   if (regNum >= UNW_ARM64_D0 && regNum <= UNW_ARM64_D31) return true;
793 #else
794   (void)regNum;
795 #endif
796   return false;
797 }
798 
799 template <typename A, typename R>
800 unw_fpreg_t UnwindCursor<A, R>::getFloatReg(int regNum) {
801 #if defined(_LIBUNWIND_TARGET_ARM)
802   if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) {
803     union {
804       uint32_t w;
805       float f;
806     } d;
807     d.w = _msContext.S[regNum - UNW_ARM_S0];
808     return d.f;
809   }
810   if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) {
811     union {
812       uint64_t w;
813       double d;
814     } d;
815     d.w = _msContext.D[regNum - UNW_ARM_D0];
816     return d.d;
817   }
818   _LIBUNWIND_ABORT("unsupported float register");
819 #elif defined(_LIBUNWIND_TARGET_AARCH64)
820   return _msContext.V[regNum - UNW_ARM64_D0].D[0];
821 #else
822   (void)regNum;
823   _LIBUNWIND_ABORT("float registers unimplemented");
824 #endif
825 }
826 
827 template <typename A, typename R>
828 void UnwindCursor<A, R>::setFloatReg(int regNum, unw_fpreg_t value) {
829 #if defined(_LIBUNWIND_TARGET_ARM)
830   if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) {
831     union {
832       uint32_t w;
833       float f;
834     } d;
835     d.f = value;
836     _msContext.S[regNum - UNW_ARM_S0] = d.w;
837   }
838   if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) {
839     union {
840       uint64_t w;
841       double d;
842     } d;
843     d.d = value;
844     _msContext.D[regNum - UNW_ARM_D0] = d.w;
845   }
846   _LIBUNWIND_ABORT("unsupported float register");
847 #elif defined(_LIBUNWIND_TARGET_AARCH64)
848   _msContext.V[regNum - UNW_ARM64_D0].D[0] = value;
849 #else
850   (void)regNum;
851   (void)value;
852   _LIBUNWIND_ABORT("float registers unimplemented");
853 #endif
854 }
855 
856 template <typename A, typename R> void UnwindCursor<A, R>::jumpto() {
857   RtlRestoreContext(&_msContext, nullptr);
858 }
859 
860 #ifdef __arm__
861 template <typename A, typename R> void UnwindCursor<A, R>::saveVFPAsX() {}
862 #endif
863 
864 template <typename A, typename R>
865 const char *UnwindCursor<A, R>::getRegisterName(int regNum) {
866   return R::getRegisterName(regNum);
867 }
868 
869 template <typename A, typename R> bool UnwindCursor<A, R>::isSignalFrame() {
870   return false;
871 }
872 
873 #else  // !defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) || !defined(_WIN32)
874 
875 /// UnwindCursor contains all state (including all register values) during
876 /// an unwind.  This is normally stack allocated inside a unw_cursor_t.
877 template <typename A, typename R>
878 class UnwindCursor : public AbstractUnwindCursor{
879   typedef typename A::pint_t pint_t;
880 public:
881                       UnwindCursor(unw_context_t *context, A &as);
882                       UnwindCursor(A &as, void *threadArg);
883   virtual             ~UnwindCursor() {}
884   virtual bool        validReg(int);
885   virtual unw_word_t  getReg(int);
886   virtual void        setReg(int, unw_word_t);
887   virtual bool        validFloatReg(int);
888   virtual unw_fpreg_t getFloatReg(int);
889   virtual void        setFloatReg(int, unw_fpreg_t);
890   virtual int         step();
891   virtual void        getInfo(unw_proc_info_t *);
892   virtual void        jumpto();
893   virtual bool        isSignalFrame();
894   virtual bool        getFunctionName(char *buf, size_t len, unw_word_t *off);
895   virtual void        setInfoBasedOnIPRegister(bool isReturnAddress = false);
896   virtual const char *getRegisterName(int num);
897 #ifdef __arm__
898   virtual void        saveVFPAsX();
899 #endif
900 
901   // libunwind does not and should not depend on C++ library which means that we
902   // need our own defition of inline placement new.
903   static void *operator new(size_t, UnwindCursor<A, R> *p) { return p; }
904 
905 private:
906 
907 #if defined(_LIBUNWIND_ARM_EHABI)
908   bool getInfoFromEHABISection(pint_t pc, const UnwindInfoSections &sects);
909 
910   int stepWithEHABI() {
911     size_t len = 0;
912     size_t off = 0;
913     // FIXME: Calling decode_eht_entry() here is violating the libunwind
914     // abstraction layer.
915     const uint32_t *ehtp =
916         decode_eht_entry(reinterpret_cast<const uint32_t *>(_info.unwind_info),
917                          &off, &len);
918     if (_Unwind_VRS_Interpret((_Unwind_Context *)this, ehtp, off, len) !=
919             _URC_CONTINUE_UNWIND)
920       return UNW_STEP_END;
921     return UNW_STEP_SUCCESS;
922   }
923 #endif
924 
925 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
926   bool getInfoFromDwarfSection(pint_t pc, const UnwindInfoSections &sects,
927                                             uint32_t fdeSectionOffsetHint=0);
928   int stepWithDwarfFDE() {
929     return DwarfInstructions<A, R>::stepWithDwarf(_addressSpace,
930                                               (pint_t)this->getReg(UNW_REG_IP),
931                                               (pint_t)_info.unwind_info,
932                                               _registers, _isSignalFrame);
933   }
934 #endif
935 
936 #if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
937   bool getInfoFromCompactEncodingSection(pint_t pc,
938                                             const UnwindInfoSections &sects);
939   int stepWithCompactEncoding() {
940   #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
941     if ( compactSaysUseDwarf() )
942       return stepWithDwarfFDE();
943   #endif
944     R dummy;
945     return stepWithCompactEncoding(dummy);
946   }
947 
948 #if defined(_LIBUNWIND_TARGET_X86_64)
949   int stepWithCompactEncoding(Registers_x86_64 &) {
950     return CompactUnwinder_x86_64<A>::stepWithCompactEncoding(
951         _info.format, _info.start_ip, _addressSpace, _registers);
952   }
953 #endif
954 
955 #if defined(_LIBUNWIND_TARGET_I386)
956   int stepWithCompactEncoding(Registers_x86 &) {
957     return CompactUnwinder_x86<A>::stepWithCompactEncoding(
958         _info.format, (uint32_t)_info.start_ip, _addressSpace, _registers);
959   }
960 #endif
961 
962 #if defined(_LIBUNWIND_TARGET_PPC)
963   int stepWithCompactEncoding(Registers_ppc &) {
964     return UNW_EINVAL;
965   }
966 #endif
967 
968 #if defined(_LIBUNWIND_TARGET_PPC64)
969   int stepWithCompactEncoding(Registers_ppc64 &) {
970     return UNW_EINVAL;
971   }
972 #endif
973 
974 
975 #if defined(_LIBUNWIND_TARGET_AARCH64)
976   int stepWithCompactEncoding(Registers_arm64 &) {
977     return CompactUnwinder_arm64<A>::stepWithCompactEncoding(
978         _info.format, _info.start_ip, _addressSpace, _registers);
979   }
980 #endif
981 
982 #if defined(_LIBUNWIND_TARGET_MIPS_O32)
983   int stepWithCompactEncoding(Registers_mips_o32 &) {
984     return UNW_EINVAL;
985   }
986 #endif
987 
988 #if defined(_LIBUNWIND_TARGET_MIPS_NEWABI)
989   int stepWithCompactEncoding(Registers_mips_newabi &) {
990     return UNW_EINVAL;
991   }
992 #endif
993 
994 #if defined(_LIBUNWIND_TARGET_SPARC)
995   int stepWithCompactEncoding(Registers_sparc &) { return UNW_EINVAL; }
996 #endif
997 
998 #if defined (_LIBUNWIND_TARGET_RISCV)
999   int stepWithCompactEncoding(Registers_riscv &) {
1000     return UNW_EINVAL;
1001   }
1002 #endif
1003 
1004   bool compactSaysUseDwarf(uint32_t *offset=NULL) const {
1005     R dummy;
1006     return compactSaysUseDwarf(dummy, offset);
1007   }
1008 
1009 #if defined(_LIBUNWIND_TARGET_X86_64)
1010   bool compactSaysUseDwarf(Registers_x86_64 &, uint32_t *offset) const {
1011     if ((_info.format & UNWIND_X86_64_MODE_MASK) == UNWIND_X86_64_MODE_DWARF) {
1012       if (offset)
1013         *offset = (_info.format & UNWIND_X86_64_DWARF_SECTION_OFFSET);
1014       return true;
1015     }
1016     return false;
1017   }
1018 #endif
1019 
1020 #if defined(_LIBUNWIND_TARGET_I386)
1021   bool compactSaysUseDwarf(Registers_x86 &, uint32_t *offset) const {
1022     if ((_info.format & UNWIND_X86_MODE_MASK) == UNWIND_X86_MODE_DWARF) {
1023       if (offset)
1024         *offset = (_info.format & UNWIND_X86_DWARF_SECTION_OFFSET);
1025       return true;
1026     }
1027     return false;
1028   }
1029 #endif
1030 
1031 #if defined(_LIBUNWIND_TARGET_PPC)
1032   bool compactSaysUseDwarf(Registers_ppc &, uint32_t *) const {
1033     return true;
1034   }
1035 #endif
1036 
1037 #if defined(_LIBUNWIND_TARGET_PPC64)
1038   bool compactSaysUseDwarf(Registers_ppc64 &, uint32_t *) const {
1039     return true;
1040   }
1041 #endif
1042 
1043 #if defined(_LIBUNWIND_TARGET_AARCH64)
1044   bool compactSaysUseDwarf(Registers_arm64 &, uint32_t *offset) const {
1045     if ((_info.format & UNWIND_ARM64_MODE_MASK) == UNWIND_ARM64_MODE_DWARF) {
1046       if (offset)
1047         *offset = (_info.format & UNWIND_ARM64_DWARF_SECTION_OFFSET);
1048       return true;
1049     }
1050     return false;
1051   }
1052 #endif
1053 
1054 #if defined(_LIBUNWIND_TARGET_MIPS_O32)
1055   bool compactSaysUseDwarf(Registers_mips_o32 &, uint32_t *) const {
1056     return true;
1057   }
1058 #endif
1059 
1060 #if defined(_LIBUNWIND_TARGET_MIPS_NEWABI)
1061   bool compactSaysUseDwarf(Registers_mips_newabi &, uint32_t *) const {
1062     return true;
1063   }
1064 #endif
1065 
1066 #if defined(_LIBUNWIND_TARGET_SPARC)
1067   bool compactSaysUseDwarf(Registers_sparc &, uint32_t *) const { return true; }
1068 #endif
1069 
1070 #if defined (_LIBUNWIND_TARGET_RISCV)
1071   bool compactSaysUseDwarf(Registers_riscv &, uint32_t *) const {
1072     return true;
1073   }
1074 #endif
1075 
1076 #endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1077 
1078 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1079   compact_unwind_encoding_t dwarfEncoding() const {
1080     R dummy;
1081     return dwarfEncoding(dummy);
1082   }
1083 
1084 #if defined(_LIBUNWIND_TARGET_X86_64)
1085   compact_unwind_encoding_t dwarfEncoding(Registers_x86_64 &) const {
1086     return UNWIND_X86_64_MODE_DWARF;
1087   }
1088 #endif
1089 
1090 #if defined(_LIBUNWIND_TARGET_I386)
1091   compact_unwind_encoding_t dwarfEncoding(Registers_x86 &) const {
1092     return UNWIND_X86_MODE_DWARF;
1093   }
1094 #endif
1095 
1096 #if defined(_LIBUNWIND_TARGET_PPC)
1097   compact_unwind_encoding_t dwarfEncoding(Registers_ppc &) const {
1098     return 0;
1099   }
1100 #endif
1101 
1102 #if defined(_LIBUNWIND_TARGET_PPC64)
1103   compact_unwind_encoding_t dwarfEncoding(Registers_ppc64 &) const {
1104     return 0;
1105   }
1106 #endif
1107 
1108 #if defined(_LIBUNWIND_TARGET_AARCH64)
1109   compact_unwind_encoding_t dwarfEncoding(Registers_arm64 &) const {
1110     return UNWIND_ARM64_MODE_DWARF;
1111   }
1112 #endif
1113 
1114 #if defined(_LIBUNWIND_TARGET_ARM)
1115   compact_unwind_encoding_t dwarfEncoding(Registers_arm &) const {
1116     return 0;
1117   }
1118 #endif
1119 
1120 #if defined (_LIBUNWIND_TARGET_OR1K)
1121   compact_unwind_encoding_t dwarfEncoding(Registers_or1k &) const {
1122     return 0;
1123   }
1124 #endif
1125 
1126 #if defined (_LIBUNWIND_TARGET_HEXAGON)
1127   compact_unwind_encoding_t dwarfEncoding(Registers_hexagon &) const {
1128     return 0;
1129   }
1130 #endif
1131 
1132 #if defined (_LIBUNWIND_TARGET_MIPS_O32)
1133   compact_unwind_encoding_t dwarfEncoding(Registers_mips_o32 &) const {
1134     return 0;
1135   }
1136 #endif
1137 
1138 #if defined (_LIBUNWIND_TARGET_MIPS_NEWABI)
1139   compact_unwind_encoding_t dwarfEncoding(Registers_mips_newabi &) const {
1140     return 0;
1141   }
1142 #endif
1143 
1144 #if defined(_LIBUNWIND_TARGET_SPARC)
1145   compact_unwind_encoding_t dwarfEncoding(Registers_sparc &) const { return 0; }
1146 #endif
1147 
1148 #if defined (_LIBUNWIND_TARGET_RISCV)
1149   compact_unwind_encoding_t dwarfEncoding(Registers_riscv &) const {
1150     return 0;
1151   }
1152 #endif
1153 
1154 #endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1155 
1156 #if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1157   // For runtime environments using SEH unwind data without Windows runtime
1158   // support.
1159   pint_t getLastPC() const { /* FIXME: Implement */ return 0; }
1160   void setLastPC(pint_t pc) { /* FIXME: Implement */ }
1161   RUNTIME_FUNCTION *lookUpSEHUnwindInfo(pint_t pc, pint_t *base) {
1162     /* FIXME: Implement */
1163     *base = 0;
1164     return nullptr;
1165   }
1166   bool getInfoFromSEH(pint_t pc);
1167   int stepWithSEHData() { /* FIXME: Implement */ return 0; }
1168 #endif // defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1169 
1170 
1171   A               &_addressSpace;
1172   R                _registers;
1173   unw_proc_info_t  _info;
1174   bool             _unwindInfoMissing;
1175   bool             _isSignalFrame;
1176 };
1177 
1178 
1179 template <typename A, typename R>
1180 UnwindCursor<A, R>::UnwindCursor(unw_context_t *context, A &as)
1181     : _addressSpace(as), _registers(context), _unwindInfoMissing(false),
1182       _isSignalFrame(false) {
1183   static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
1184                 "UnwindCursor<> does not fit in unw_cursor_t");
1185   memset(&_info, 0, sizeof(_info));
1186 }
1187 
1188 template <typename A, typename R>
1189 UnwindCursor<A, R>::UnwindCursor(A &as, void *)
1190     : _addressSpace(as), _unwindInfoMissing(false), _isSignalFrame(false) {
1191   memset(&_info, 0, sizeof(_info));
1192   // FIXME
1193   // fill in _registers from thread arg
1194 }
1195 
1196 
1197 template <typename A, typename R>
1198 bool UnwindCursor<A, R>::validReg(int regNum) {
1199   return _registers.validRegister(regNum);
1200 }
1201 
1202 template <typename A, typename R>
1203 unw_word_t UnwindCursor<A, R>::getReg(int regNum) {
1204   return _registers.getRegister(regNum);
1205 }
1206 
1207 template <typename A, typename R>
1208 void UnwindCursor<A, R>::setReg(int regNum, unw_word_t value) {
1209   _registers.setRegister(regNum, (typename A::pint_t)value);
1210 }
1211 
1212 template <typename A, typename R>
1213 bool UnwindCursor<A, R>::validFloatReg(int regNum) {
1214   return _registers.validFloatRegister(regNum);
1215 }
1216 
1217 template <typename A, typename R>
1218 unw_fpreg_t UnwindCursor<A, R>::getFloatReg(int regNum) {
1219   return _registers.getFloatRegister(regNum);
1220 }
1221 
1222 template <typename A, typename R>
1223 void UnwindCursor<A, R>::setFloatReg(int regNum, unw_fpreg_t value) {
1224   _registers.setFloatRegister(regNum, value);
1225 }
1226 
1227 template <typename A, typename R> void UnwindCursor<A, R>::jumpto() {
1228   _registers.jumpto();
1229 }
1230 
1231 #ifdef __arm__
1232 template <typename A, typename R> void UnwindCursor<A, R>::saveVFPAsX() {
1233   _registers.saveVFPAsX();
1234 }
1235 #endif
1236 
1237 template <typename A, typename R>
1238 const char *UnwindCursor<A, R>::getRegisterName(int regNum) {
1239   return _registers.getRegisterName(regNum);
1240 }
1241 
1242 template <typename A, typename R> bool UnwindCursor<A, R>::isSignalFrame() {
1243   return _isSignalFrame;
1244 }
1245 
1246 #endif // defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1247 
1248 #if defined(_LIBUNWIND_ARM_EHABI)
1249 template<typename A>
1250 struct EHABISectionIterator {
1251   typedef EHABISectionIterator _Self;
1252 
1253   typedef typename A::pint_t value_type;
1254   typedef typename A::pint_t* pointer;
1255   typedef typename A::pint_t& reference;
1256   typedef size_t size_type;
1257   typedef size_t difference_type;
1258 
1259   static _Self begin(A& addressSpace, const UnwindInfoSections& sects) {
1260     return _Self(addressSpace, sects, 0);
1261   }
1262   static _Self end(A& addressSpace, const UnwindInfoSections& sects) {
1263     return _Self(addressSpace, sects,
1264                  sects.arm_section_length / sizeof(EHABIIndexEntry));
1265   }
1266 
1267   EHABISectionIterator(A& addressSpace, const UnwindInfoSections& sects, size_t i)
1268       : _i(i), _addressSpace(&addressSpace), _sects(&sects) {}
1269 
1270   _Self& operator++() { ++_i; return *this; }
1271   _Self& operator+=(size_t a) { _i += a; return *this; }
1272   _Self& operator--() { assert(_i > 0); --_i; return *this; }
1273   _Self& operator-=(size_t a) { assert(_i >= a); _i -= a; return *this; }
1274 
1275   _Self operator+(size_t a) { _Self out = *this; out._i += a; return out; }
1276   _Self operator-(size_t a) { assert(_i >= a); _Self out = *this; out._i -= a; return out; }
1277 
1278   size_t operator-(const _Self& other) const { return _i - other._i; }
1279 
1280   bool operator==(const _Self& other) const {
1281     assert(_addressSpace == other._addressSpace);
1282     assert(_sects == other._sects);
1283     return _i == other._i;
1284   }
1285 
1286   bool operator!=(const _Self& other) const {
1287     assert(_addressSpace == other._addressSpace);
1288     assert(_sects == other._sects);
1289     return _i != other._i;
1290   }
1291 
1292   typename A::pint_t operator*() const { return functionAddress(); }
1293 
1294   typename A::pint_t functionAddress() const {
1295     typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
1296         EHABIIndexEntry, _i, functionOffset);
1297     return indexAddr + signExtendPrel31(_addressSpace->get32(indexAddr));
1298   }
1299 
1300   typename A::pint_t dataAddress() {
1301     typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
1302         EHABIIndexEntry, _i, data);
1303     return indexAddr;
1304   }
1305 
1306  private:
1307   size_t _i;
1308   A* _addressSpace;
1309   const UnwindInfoSections* _sects;
1310 };
1311 
1312 namespace {
1313 
1314 template <typename A>
1315 EHABISectionIterator<A> EHABISectionUpperBound(
1316     EHABISectionIterator<A> first,
1317     EHABISectionIterator<A> last,
1318     typename A::pint_t value) {
1319   size_t len = last - first;
1320   while (len > 0) {
1321     size_t l2 = len / 2;
1322     EHABISectionIterator<A> m = first + l2;
1323     if (value < *m) {
1324         len = l2;
1325     } else {
1326         first = ++m;
1327         len -= l2 + 1;
1328     }
1329   }
1330   return first;
1331 }
1332 
1333 }
1334 
1335 template <typename A, typename R>
1336 bool UnwindCursor<A, R>::getInfoFromEHABISection(
1337     pint_t pc,
1338     const UnwindInfoSections &sects) {
1339   EHABISectionIterator<A> begin =
1340       EHABISectionIterator<A>::begin(_addressSpace, sects);
1341   EHABISectionIterator<A> end =
1342       EHABISectionIterator<A>::end(_addressSpace, sects);
1343   if (begin == end)
1344     return false;
1345 
1346   EHABISectionIterator<A> itNextPC = EHABISectionUpperBound(begin, end, pc);
1347   if (itNextPC == begin)
1348     return false;
1349   EHABISectionIterator<A> itThisPC = itNextPC - 1;
1350 
1351   pint_t thisPC = itThisPC.functionAddress();
1352   // If an exception is thrown from a function, corresponding to the last entry
1353   // in the table, we don't really know the function extent and have to choose a
1354   // value for nextPC. Choosing max() will allow the range check during trace to
1355   // succeed.
1356   pint_t nextPC = (itNextPC == end) ? UINTPTR_MAX : itNextPC.functionAddress();
1357   pint_t indexDataAddr = itThisPC.dataAddress();
1358 
1359   if (indexDataAddr == 0)
1360     return false;
1361 
1362   uint32_t indexData = _addressSpace.get32(indexDataAddr);
1363   if (indexData == UNW_EXIDX_CANTUNWIND)
1364     return false;
1365 
1366   // If the high bit is set, the exception handling table entry is inline inside
1367   // the index table entry on the second word (aka |indexDataAddr|). Otherwise,
1368   // the table points at an offset in the exception handling table (section 5
1369   // EHABI).
1370   pint_t exceptionTableAddr;
1371   uint32_t exceptionTableData;
1372   bool isSingleWordEHT;
1373   if (indexData & 0x80000000) {
1374     exceptionTableAddr = indexDataAddr;
1375     // TODO(ajwong): Should this data be 0?
1376     exceptionTableData = indexData;
1377     isSingleWordEHT = true;
1378   } else {
1379     exceptionTableAddr = indexDataAddr + signExtendPrel31(indexData);
1380     exceptionTableData = _addressSpace.get32(exceptionTableAddr);
1381     isSingleWordEHT = false;
1382   }
1383 
1384   // Now we know the 3 things:
1385   //   exceptionTableAddr -- exception handler table entry.
1386   //   exceptionTableData -- the data inside the first word of the eht entry.
1387   //   isSingleWordEHT -- whether the entry is in the index.
1388   unw_word_t personalityRoutine = 0xbadf00d;
1389   bool scope32 = false;
1390   uintptr_t lsda;
1391 
1392   // If the high bit in the exception handling table entry is set, the entry is
1393   // in compact form (section 6.3 EHABI).
1394   if (exceptionTableData & 0x80000000) {
1395     // Grab the index of the personality routine from the compact form.
1396     uint32_t choice = (exceptionTableData & 0x0f000000) >> 24;
1397     uint32_t extraWords = 0;
1398     switch (choice) {
1399       case 0:
1400         personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr0;
1401         extraWords = 0;
1402         scope32 = false;
1403         lsda = isSingleWordEHT ? 0 : (exceptionTableAddr + 4);
1404         break;
1405       case 1:
1406         personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr1;
1407         extraWords = (exceptionTableData & 0x00ff0000) >> 16;
1408         scope32 = false;
1409         lsda = exceptionTableAddr + (extraWords + 1) * 4;
1410         break;
1411       case 2:
1412         personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr2;
1413         extraWords = (exceptionTableData & 0x00ff0000) >> 16;
1414         scope32 = true;
1415         lsda = exceptionTableAddr + (extraWords + 1) * 4;
1416         break;
1417       default:
1418         _LIBUNWIND_ABORT("unknown personality routine");
1419         return false;
1420     }
1421 
1422     if (isSingleWordEHT) {
1423       if (extraWords != 0) {
1424         _LIBUNWIND_ABORT("index inlined table detected but pr function "
1425                          "requires extra words");
1426         return false;
1427       }
1428     }
1429   } else {
1430     pint_t personalityAddr =
1431         exceptionTableAddr + signExtendPrel31(exceptionTableData);
1432     personalityRoutine = personalityAddr;
1433 
1434     // ARM EHABI # 6.2, # 9.2
1435     //
1436     //  +---- ehtp
1437     //  v
1438     // +--------------------------------------+
1439     // | +--------+--------+--------+-------+ |
1440     // | |0| prel31 to personalityRoutine   | |
1441     // | +--------+--------+--------+-------+ |
1442     // | |      N |      unwind opcodes     | |  <-- UnwindData
1443     // | +--------+--------+--------+-------+ |
1444     // | | Word 2        unwind opcodes     | |
1445     // | +--------+--------+--------+-------+ |
1446     // | ...                                  |
1447     // | +--------+--------+--------+-------+ |
1448     // | | Word N        unwind opcodes     | |
1449     // | +--------+--------+--------+-------+ |
1450     // | | LSDA                             | |  <-- lsda
1451     // | | ...                              | |
1452     // | +--------+--------+--------+-------+ |
1453     // +--------------------------------------+
1454 
1455     uint32_t *UnwindData = reinterpret_cast<uint32_t*>(exceptionTableAddr) + 1;
1456     uint32_t FirstDataWord = *UnwindData;
1457     size_t N = ((FirstDataWord >> 24) & 0xff);
1458     size_t NDataWords = N + 1;
1459     lsda = reinterpret_cast<uintptr_t>(UnwindData + NDataWords);
1460   }
1461 
1462   _info.start_ip = thisPC;
1463   _info.end_ip = nextPC;
1464   _info.handler = personalityRoutine;
1465   _info.unwind_info = exceptionTableAddr;
1466   _info.lsda = lsda;
1467   // flags is pr_cache.additional. See EHABI #7.2 for definition of bit 0.
1468   _info.flags = (isSingleWordEHT ? 1 : 0) | (scope32 ? 0x2 : 0);  // Use enum?
1469 
1470   return true;
1471 }
1472 #endif
1473 
1474 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1475 template <typename A, typename R>
1476 bool UnwindCursor<A, R>::getInfoFromDwarfSection(pint_t pc,
1477                                                 const UnwindInfoSections &sects,
1478                                                 uint32_t fdeSectionOffsetHint) {
1479   typename CFI_Parser<A>::FDE_Info fdeInfo;
1480   typename CFI_Parser<A>::CIE_Info cieInfo;
1481   bool foundFDE = false;
1482   bool foundInCache = false;
1483   // If compact encoding table gave offset into dwarf section, go directly there
1484   if (fdeSectionOffsetHint != 0) {
1485     foundFDE = CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
1486                                     (uint32_t)sects.dwarf_section_length,
1487                                     sects.dwarf_section + fdeSectionOffsetHint,
1488                                     &fdeInfo, &cieInfo);
1489   }
1490 #if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
1491   if (!foundFDE && (sects.dwarf_index_section != 0)) {
1492     foundFDE = EHHeaderParser<A>::findFDE(
1493         _addressSpace, pc, sects.dwarf_index_section,
1494         (uint32_t)sects.dwarf_index_section_length, &fdeInfo, &cieInfo);
1495   }
1496 #endif
1497   if (!foundFDE) {
1498     // otherwise, search cache of previously found FDEs.
1499     pint_t cachedFDE = DwarfFDECache<A>::findFDE(sects.dso_base, pc);
1500     if (cachedFDE != 0) {
1501       foundFDE =
1502           CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
1503                                  (uint32_t)sects.dwarf_section_length,
1504                                  cachedFDE, &fdeInfo, &cieInfo);
1505       foundInCache = foundFDE;
1506     }
1507   }
1508   if (!foundFDE) {
1509     // Still not found, do full scan of __eh_frame section.
1510     foundFDE = CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
1511                                       (uint32_t)sects.dwarf_section_length, 0,
1512                                       &fdeInfo, &cieInfo);
1513   }
1514   if (foundFDE) {
1515     typename CFI_Parser<A>::PrologInfo prolog;
1516     if (CFI_Parser<A>::parseFDEInstructions(_addressSpace, fdeInfo, cieInfo, pc,
1517                                             R::getArch(), &prolog)) {
1518       // Save off parsed FDE info
1519       _info.start_ip          = fdeInfo.pcStart;
1520       _info.end_ip            = fdeInfo.pcEnd;
1521       _info.lsda              = fdeInfo.lsda;
1522       _info.handler           = cieInfo.personality;
1523       _info.gp                = prolog.spExtraArgSize;
1524       _info.flags             = 0;
1525       _info.format            = dwarfEncoding();
1526       _info.unwind_info       = fdeInfo.fdeStart;
1527       _info.unwind_info_size  = (uint32_t)fdeInfo.fdeLength;
1528       _info.extra             = (unw_word_t) sects.dso_base;
1529 
1530       // Add to cache (to make next lookup faster) if we had no hint
1531       // and there was no index.
1532       if (!foundInCache && (fdeSectionOffsetHint == 0)) {
1533   #if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
1534         if (sects.dwarf_index_section == 0)
1535   #endif
1536         DwarfFDECache<A>::add(sects.dso_base, fdeInfo.pcStart, fdeInfo.pcEnd,
1537                               fdeInfo.fdeStart);
1538       }
1539       return true;
1540     }
1541   }
1542   //_LIBUNWIND_DEBUG_LOG("can't find/use FDE for pc=0x%llX", (uint64_t)pc);
1543   return false;
1544 }
1545 #endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1546 
1547 
1548 #if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1549 template <typename A, typename R>
1550 bool UnwindCursor<A, R>::getInfoFromCompactEncodingSection(pint_t pc,
1551                                               const UnwindInfoSections &sects) {
1552   const bool log = false;
1553   if (log)
1554     fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX, mh=0x%llX)\n",
1555             (uint64_t)pc, (uint64_t)sects.dso_base);
1556 
1557   const UnwindSectionHeader<A> sectionHeader(_addressSpace,
1558                                                 sects.compact_unwind_section);
1559   if (sectionHeader.version() != UNWIND_SECTION_VERSION)
1560     return false;
1561 
1562   // do a binary search of top level index to find page with unwind info
1563   pint_t targetFunctionOffset = pc - sects.dso_base;
1564   const UnwindSectionIndexArray<A> topIndex(_addressSpace,
1565                                            sects.compact_unwind_section
1566                                          + sectionHeader.indexSectionOffset());
1567   uint32_t low = 0;
1568   uint32_t high = sectionHeader.indexCount();
1569   uint32_t last = high - 1;
1570   while (low < high) {
1571     uint32_t mid = (low + high) / 2;
1572     //if ( log ) fprintf(stderr, "\tmid=%d, low=%d, high=%d, *mid=0x%08X\n",
1573     //mid, low, high, topIndex.functionOffset(mid));
1574     if (topIndex.functionOffset(mid) <= targetFunctionOffset) {
1575       if ((mid == last) ||
1576           (topIndex.functionOffset(mid + 1) > targetFunctionOffset)) {
1577         low = mid;
1578         break;
1579       } else {
1580         low = mid + 1;
1581       }
1582     } else {
1583       high = mid;
1584     }
1585   }
1586   const uint32_t firstLevelFunctionOffset = topIndex.functionOffset(low);
1587   const uint32_t firstLevelNextPageFunctionOffset =
1588       topIndex.functionOffset(low + 1);
1589   const pint_t secondLevelAddr =
1590       sects.compact_unwind_section + topIndex.secondLevelPagesSectionOffset(low);
1591   const pint_t lsdaArrayStartAddr =
1592       sects.compact_unwind_section + topIndex.lsdaIndexArraySectionOffset(low);
1593   const pint_t lsdaArrayEndAddr =
1594       sects.compact_unwind_section + topIndex.lsdaIndexArraySectionOffset(low+1);
1595   if (log)
1596     fprintf(stderr, "\tfirst level search for result index=%d "
1597                     "to secondLevelAddr=0x%llX\n",
1598                     low, (uint64_t) secondLevelAddr);
1599   // do a binary search of second level page index
1600   uint32_t encoding = 0;
1601   pint_t funcStart = 0;
1602   pint_t funcEnd = 0;
1603   pint_t lsda = 0;
1604   pint_t personality = 0;
1605   uint32_t pageKind = _addressSpace.get32(secondLevelAddr);
1606   if (pageKind == UNWIND_SECOND_LEVEL_REGULAR) {
1607     // regular page
1608     UnwindSectionRegularPageHeader<A> pageHeader(_addressSpace,
1609                                                  secondLevelAddr);
1610     UnwindSectionRegularArray<A> pageIndex(
1611         _addressSpace, secondLevelAddr + pageHeader.entryPageOffset());
1612     // binary search looks for entry with e where index[e].offset <= pc <
1613     // index[e+1].offset
1614     if (log)
1615       fprintf(stderr, "\tbinary search for targetFunctionOffset=0x%08llX in "
1616                       "regular page starting at secondLevelAddr=0x%llX\n",
1617               (uint64_t) targetFunctionOffset, (uint64_t) secondLevelAddr);
1618     low = 0;
1619     high = pageHeader.entryCount();
1620     while (low < high) {
1621       uint32_t mid = (low + high) / 2;
1622       if (pageIndex.functionOffset(mid) <= targetFunctionOffset) {
1623         if (mid == (uint32_t)(pageHeader.entryCount() - 1)) {
1624           // at end of table
1625           low = mid;
1626           funcEnd = firstLevelNextPageFunctionOffset + sects.dso_base;
1627           break;
1628         } else if (pageIndex.functionOffset(mid + 1) > targetFunctionOffset) {
1629           // next is too big, so we found it
1630           low = mid;
1631           funcEnd = pageIndex.functionOffset(low + 1) + sects.dso_base;
1632           break;
1633         } else {
1634           low = mid + 1;
1635         }
1636       } else {
1637         high = mid;
1638       }
1639     }
1640     encoding = pageIndex.encoding(low);
1641     funcStart = pageIndex.functionOffset(low) + sects.dso_base;
1642     if (pc < funcStart) {
1643       if (log)
1644         fprintf(
1645             stderr,
1646             "\tpc not in table, pc=0x%llX, funcStart=0x%llX, funcEnd=0x%llX\n",
1647             (uint64_t) pc, (uint64_t) funcStart, (uint64_t) funcEnd);
1648       return false;
1649     }
1650     if (pc > funcEnd) {
1651       if (log)
1652         fprintf(
1653             stderr,
1654             "\tpc not in table, pc=0x%llX, funcStart=0x%llX, funcEnd=0x%llX\n",
1655             (uint64_t) pc, (uint64_t) funcStart, (uint64_t) funcEnd);
1656       return false;
1657     }
1658   } else if (pageKind == UNWIND_SECOND_LEVEL_COMPRESSED) {
1659     // compressed page
1660     UnwindSectionCompressedPageHeader<A> pageHeader(_addressSpace,
1661                                                     secondLevelAddr);
1662     UnwindSectionCompressedArray<A> pageIndex(
1663         _addressSpace, secondLevelAddr + pageHeader.entryPageOffset());
1664     const uint32_t targetFunctionPageOffset =
1665         (uint32_t)(targetFunctionOffset - firstLevelFunctionOffset);
1666     // binary search looks for entry with e where index[e].offset <= pc <
1667     // index[e+1].offset
1668     if (log)
1669       fprintf(stderr, "\tbinary search of compressed page starting at "
1670                       "secondLevelAddr=0x%llX\n",
1671               (uint64_t) secondLevelAddr);
1672     low = 0;
1673     last = pageHeader.entryCount() - 1;
1674     high = pageHeader.entryCount();
1675     while (low < high) {
1676       uint32_t mid = (low + high) / 2;
1677       if (pageIndex.functionOffset(mid) <= targetFunctionPageOffset) {
1678         if ((mid == last) ||
1679             (pageIndex.functionOffset(mid + 1) > targetFunctionPageOffset)) {
1680           low = mid;
1681           break;
1682         } else {
1683           low = mid + 1;
1684         }
1685       } else {
1686         high = mid;
1687       }
1688     }
1689     funcStart = pageIndex.functionOffset(low) + firstLevelFunctionOffset
1690                                                               + sects.dso_base;
1691     if (low < last)
1692       funcEnd =
1693           pageIndex.functionOffset(low + 1) + firstLevelFunctionOffset
1694                                                               + sects.dso_base;
1695     else
1696       funcEnd = firstLevelNextPageFunctionOffset + sects.dso_base;
1697     if (pc < funcStart) {
1698       _LIBUNWIND_DEBUG_LOG("malformed __unwind_info, pc=0x%llX not in second  "
1699                            "level compressed unwind table. funcStart=0x%llX",
1700                             (uint64_t) pc, (uint64_t) funcStart);
1701       return false;
1702     }
1703     if (pc > funcEnd) {
1704       _LIBUNWIND_DEBUG_LOG("malformed __unwind_info, pc=0x%llX not in second  "
1705                           "level compressed unwind table. funcEnd=0x%llX",
1706                            (uint64_t) pc, (uint64_t) funcEnd);
1707       return false;
1708     }
1709     uint16_t encodingIndex = pageIndex.encodingIndex(low);
1710     if (encodingIndex < sectionHeader.commonEncodingsArrayCount()) {
1711       // encoding is in common table in section header
1712       encoding = _addressSpace.get32(
1713           sects.compact_unwind_section +
1714           sectionHeader.commonEncodingsArraySectionOffset() +
1715           encodingIndex * sizeof(uint32_t));
1716     } else {
1717       // encoding is in page specific table
1718       uint16_t pageEncodingIndex =
1719           encodingIndex - (uint16_t)sectionHeader.commonEncodingsArrayCount();
1720       encoding = _addressSpace.get32(secondLevelAddr +
1721                                      pageHeader.encodingsPageOffset() +
1722                                      pageEncodingIndex * sizeof(uint32_t));
1723     }
1724   } else {
1725     _LIBUNWIND_DEBUG_LOG("malformed __unwind_info at 0x%0llX bad second "
1726                          "level page",
1727                           (uint64_t) sects.compact_unwind_section);
1728     return false;
1729   }
1730 
1731   // look up LSDA, if encoding says function has one
1732   if (encoding & UNWIND_HAS_LSDA) {
1733     UnwindSectionLsdaArray<A> lsdaIndex(_addressSpace, lsdaArrayStartAddr);
1734     uint32_t funcStartOffset = (uint32_t)(funcStart - sects.dso_base);
1735     low = 0;
1736     high = (uint32_t)(lsdaArrayEndAddr - lsdaArrayStartAddr) /
1737                     sizeof(unwind_info_section_header_lsda_index_entry);
1738     // binary search looks for entry with exact match for functionOffset
1739     if (log)
1740       fprintf(stderr,
1741               "\tbinary search of lsda table for targetFunctionOffset=0x%08X\n",
1742               funcStartOffset);
1743     while (low < high) {
1744       uint32_t mid = (low + high) / 2;
1745       if (lsdaIndex.functionOffset(mid) == funcStartOffset) {
1746         lsda = lsdaIndex.lsdaOffset(mid) + sects.dso_base;
1747         break;
1748       } else if (lsdaIndex.functionOffset(mid) < funcStartOffset) {
1749         low = mid + 1;
1750       } else {
1751         high = mid;
1752       }
1753     }
1754     if (lsda == 0) {
1755       _LIBUNWIND_DEBUG_LOG("found encoding 0x%08X with HAS_LSDA bit set for "
1756                     "pc=0x%0llX, but lsda table has no entry",
1757                     encoding, (uint64_t) pc);
1758       return false;
1759     }
1760   }
1761 
1762   // extact personality routine, if encoding says function has one
1763   uint32_t personalityIndex = (encoding & UNWIND_PERSONALITY_MASK) >>
1764                               (__builtin_ctz(UNWIND_PERSONALITY_MASK));
1765   if (personalityIndex != 0) {
1766     --personalityIndex; // change 1-based to zero-based index
1767     if (personalityIndex > sectionHeader.personalityArrayCount()) {
1768       _LIBUNWIND_DEBUG_LOG("found encoding 0x%08X with personality index %d,  "
1769                             "but personality table has only %d entries",
1770                             encoding, personalityIndex,
1771                             sectionHeader.personalityArrayCount());
1772       return false;
1773     }
1774     int32_t personalityDelta = (int32_t)_addressSpace.get32(
1775         sects.compact_unwind_section +
1776         sectionHeader.personalityArraySectionOffset() +
1777         personalityIndex * sizeof(uint32_t));
1778     pint_t personalityPointer = sects.dso_base + (pint_t)personalityDelta;
1779     personality = _addressSpace.getP(personalityPointer);
1780     if (log)
1781       fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX), "
1782                       "personalityDelta=0x%08X, personality=0x%08llX\n",
1783               (uint64_t) pc, personalityDelta, (uint64_t) personality);
1784   }
1785 
1786   if (log)
1787     fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX), "
1788                     "encoding=0x%08X, lsda=0x%08llX for funcStart=0x%llX\n",
1789             (uint64_t) pc, encoding, (uint64_t) lsda, (uint64_t) funcStart);
1790   _info.start_ip = funcStart;
1791   _info.end_ip = funcEnd;
1792   _info.lsda = lsda;
1793   _info.handler = personality;
1794   _info.gp = 0;
1795   _info.flags = 0;
1796   _info.format = encoding;
1797   _info.unwind_info = 0;
1798   _info.unwind_info_size = 0;
1799   _info.extra = sects.dso_base;
1800   return true;
1801 }
1802 #endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1803 
1804 
1805 #if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1806 template <typename A, typename R>
1807 bool UnwindCursor<A, R>::getInfoFromSEH(pint_t pc) {
1808   pint_t base;
1809   RUNTIME_FUNCTION *unwindEntry = lookUpSEHUnwindInfo(pc, &base);
1810   if (!unwindEntry) {
1811     _LIBUNWIND_DEBUG_LOG("\tpc not in table, pc=0x%llX", (uint64_t) pc);
1812     return false;
1813   }
1814   _info.gp = 0;
1815   _info.flags = 0;
1816   _info.format = 0;
1817   _info.unwind_info_size = sizeof(RUNTIME_FUNCTION);
1818   _info.unwind_info = reinterpret_cast<unw_word_t>(unwindEntry);
1819   _info.extra = base;
1820   _info.start_ip = base + unwindEntry->BeginAddress;
1821 #ifdef _LIBUNWIND_TARGET_X86_64
1822   _info.end_ip = base + unwindEntry->EndAddress;
1823   // Only fill in the handler and LSDA if they're stale.
1824   if (pc != getLastPC()) {
1825     UNWIND_INFO *xdata = reinterpret_cast<UNWIND_INFO *>(base + unwindEntry->UnwindData);
1826     if (xdata->Flags & (UNW_FLAG_EHANDLER|UNW_FLAG_UHANDLER)) {
1827       // The personality is given in the UNWIND_INFO itself. The LSDA immediately
1828       // follows the UNWIND_INFO. (This follows how both Clang and MSVC emit
1829       // these structures.)
1830       // N.B. UNWIND_INFO structs are DWORD-aligned.
1831       uint32_t lastcode = (xdata->CountOfCodes + 1) & ~1;
1832       const uint32_t *handler = reinterpret_cast<uint32_t *>(&xdata->UnwindCodes[lastcode]);
1833       _info.lsda = reinterpret_cast<unw_word_t>(handler+1);
1834       if (*handler) {
1835         _info.handler = reinterpret_cast<unw_word_t>(__libunwind_seh_personality);
1836       } else
1837         _info.handler = 0;
1838     } else {
1839       _info.lsda = 0;
1840       _info.handler = 0;
1841     }
1842   }
1843 #elif defined(_LIBUNWIND_TARGET_ARM)
1844   _info.end_ip = _info.start_ip + unwindEntry->FunctionLength;
1845   _info.lsda = 0; // FIXME
1846   _info.handler = 0; // FIXME
1847 #endif
1848   setLastPC(pc);
1849   return true;
1850 }
1851 #endif
1852 
1853 
1854 template <typename A, typename R>
1855 void UnwindCursor<A, R>::setInfoBasedOnIPRegister(bool isReturnAddress) {
1856   pint_t pc = (pint_t)this->getReg(UNW_REG_IP);
1857 #if defined(_LIBUNWIND_ARM_EHABI)
1858   // Remove the thumb bit so the IP represents the actual instruction address.
1859   // This matches the behaviour of _Unwind_GetIP on arm.
1860   pc &= (pint_t)~0x1;
1861 #endif
1862 
1863   // Exit early if at the top of the stack.
1864   if (pc == 0) {
1865     _unwindInfoMissing = true;
1866     return;
1867   }
1868 
1869   // If the last line of a function is a "throw" the compiler sometimes
1870   // emits no instructions after the call to __cxa_throw.  This means
1871   // the return address is actually the start of the next function.
1872   // To disambiguate this, back up the pc when we know it is a return
1873   // address.
1874   if (isReturnAddress)
1875     --pc;
1876 
1877   // Ask address space object to find unwind sections for this pc.
1878   UnwindInfoSections sects;
1879   if (_addressSpace.findUnwindSections(pc, sects)) {
1880 #if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1881     // If there is a compact unwind encoding table, look there first.
1882     if (sects.compact_unwind_section != 0) {
1883       if (this->getInfoFromCompactEncodingSection(pc, sects)) {
1884   #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1885         // Found info in table, done unless encoding says to use dwarf.
1886         uint32_t dwarfOffset;
1887         if ((sects.dwarf_section != 0) && compactSaysUseDwarf(&dwarfOffset)) {
1888           if (this->getInfoFromDwarfSection(pc, sects, dwarfOffset)) {
1889             // found info in dwarf, done
1890             return;
1891           }
1892         }
1893   #endif
1894         // If unwind table has entry, but entry says there is no unwind info,
1895         // record that we have no unwind info.
1896         if (_info.format == 0)
1897           _unwindInfoMissing = true;
1898         return;
1899       }
1900     }
1901 #endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1902 
1903 #if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1904     // If there is SEH unwind info, look there next.
1905     if (this->getInfoFromSEH(pc))
1906       return;
1907 #endif
1908 
1909 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1910     // If there is dwarf unwind info, look there next.
1911     if (sects.dwarf_section != 0) {
1912       if (this->getInfoFromDwarfSection(pc, sects)) {
1913         // found info in dwarf, done
1914         return;
1915       }
1916     }
1917 #endif
1918 
1919 #if defined(_LIBUNWIND_ARM_EHABI)
1920     // If there is ARM EHABI unwind info, look there next.
1921     if (sects.arm_section != 0 && this->getInfoFromEHABISection(pc, sects))
1922       return;
1923 #endif
1924   }
1925 
1926 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1927   // There is no static unwind info for this pc. Look to see if an FDE was
1928   // dynamically registered for it.
1929   pint_t cachedFDE = DwarfFDECache<A>::findFDE(0, pc);
1930   if (cachedFDE != 0) {
1931     CFI_Parser<LocalAddressSpace>::FDE_Info fdeInfo;
1932     CFI_Parser<LocalAddressSpace>::CIE_Info cieInfo;
1933     const char *msg = CFI_Parser<A>::decodeFDE(_addressSpace,
1934                                                 cachedFDE, &fdeInfo, &cieInfo);
1935     if (msg == NULL) {
1936       typename CFI_Parser<A>::PrologInfo prolog;
1937       if (CFI_Parser<A>::parseFDEInstructions(_addressSpace, fdeInfo, cieInfo,
1938                                               pc, R::getArch(), &prolog)) {
1939         // save off parsed FDE info
1940         _info.start_ip         = fdeInfo.pcStart;
1941         _info.end_ip           = fdeInfo.pcEnd;
1942         _info.lsda             = fdeInfo.lsda;
1943         _info.handler          = cieInfo.personality;
1944         _info.gp               = prolog.spExtraArgSize;
1945                                   // Some frameless functions need SP
1946                                   // altered when resuming in function.
1947         _info.flags            = 0;
1948         _info.format           = dwarfEncoding();
1949         _info.unwind_info      = fdeInfo.fdeStart;
1950         _info.unwind_info_size = (uint32_t)fdeInfo.fdeLength;
1951         _info.extra            = 0;
1952         return;
1953       }
1954     }
1955   }
1956 
1957   // Lastly, ask AddressSpace object about platform specific ways to locate
1958   // other FDEs.
1959   pint_t fde;
1960   if (_addressSpace.findOtherFDE(pc, fde)) {
1961     CFI_Parser<LocalAddressSpace>::FDE_Info fdeInfo;
1962     CFI_Parser<LocalAddressSpace>::CIE_Info cieInfo;
1963     if (!CFI_Parser<A>::decodeFDE(_addressSpace, fde, &fdeInfo, &cieInfo)) {
1964       // Double check this FDE is for a function that includes the pc.
1965       if ((fdeInfo.pcStart <= pc) && (pc < fdeInfo.pcEnd)) {
1966         typename CFI_Parser<A>::PrologInfo prolog;
1967         if (CFI_Parser<A>::parseFDEInstructions(_addressSpace, fdeInfo, cieInfo,
1968                                                 pc, R::getArch(), &prolog)) {
1969           // save off parsed FDE info
1970           _info.start_ip         = fdeInfo.pcStart;
1971           _info.end_ip           = fdeInfo.pcEnd;
1972           _info.lsda             = fdeInfo.lsda;
1973           _info.handler          = cieInfo.personality;
1974           _info.gp               = prolog.spExtraArgSize;
1975           _info.flags            = 0;
1976           _info.format           = dwarfEncoding();
1977           _info.unwind_info      = fdeInfo.fdeStart;
1978           _info.unwind_info_size = (uint32_t)fdeInfo.fdeLength;
1979           _info.extra            = 0;
1980           return;
1981         }
1982       }
1983     }
1984   }
1985 #endif // #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1986 
1987   // no unwind info, flag that we can't reliably unwind
1988   _unwindInfoMissing = true;
1989 }
1990 
1991 template <typename A, typename R>
1992 int UnwindCursor<A, R>::step() {
1993   // Bottom of stack is defined is when unwind info cannot be found.
1994   if (_unwindInfoMissing)
1995     return UNW_STEP_END;
1996 
1997   // Use unwinding info to modify register set as if function returned.
1998   int result;
1999 #if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
2000   result = this->stepWithCompactEncoding();
2001 #elif defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
2002   result = this->stepWithSEHData();
2003 #elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
2004   result = this->stepWithDwarfFDE();
2005 #elif defined(_LIBUNWIND_ARM_EHABI)
2006   result = this->stepWithEHABI();
2007 #else
2008   #error Need _LIBUNWIND_SUPPORT_COMPACT_UNWIND or \
2009               _LIBUNWIND_SUPPORT_SEH_UNWIND or \
2010               _LIBUNWIND_SUPPORT_DWARF_UNWIND or \
2011               _LIBUNWIND_ARM_EHABI
2012 #endif
2013 
2014   // update info based on new PC
2015   if (result == UNW_STEP_SUCCESS) {
2016     this->setInfoBasedOnIPRegister(true);
2017     if (_unwindInfoMissing)
2018       return UNW_STEP_END;
2019   }
2020 
2021   return result;
2022 }
2023 
2024 template <typename A, typename R>
2025 void UnwindCursor<A, R>::getInfo(unw_proc_info_t *info) {
2026   if (_unwindInfoMissing)
2027     memset(info, 0, sizeof(*info));
2028   else
2029     *info = _info;
2030 }
2031 
2032 template <typename A, typename R>
2033 bool UnwindCursor<A, R>::getFunctionName(char *buf, size_t bufLen,
2034                                                            unw_word_t *offset) {
2035   return _addressSpace.findFunctionName((pint_t)this->getReg(UNW_REG_IP),
2036                                          buf, bufLen, offset);
2037 }
2038 
2039 } // namespace libunwind
2040 
2041 #endif // __UNWINDCURSOR_HPP__
2042