xref: /freebsd/contrib/llvm-project/libunwind/src/UnwindCursor.hpp (revision af23369a6deaaeb612ab266eb88b8bb8d560c322)
1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //
8 // C++ interface to lower levels of libunwind
9 //===----------------------------------------------------------------------===//
10 
11 #ifndef __UNWINDCURSOR_HPP__
12 #define __UNWINDCURSOR_HPP__
13 
14 #include "cet_unwind.h"
15 #include <stdint.h>
16 #include <stdio.h>
17 #include <stdlib.h>
18 #include <unwind.h>
19 
20 #ifdef _WIN32
21   #include <windows.h>
22   #include <ntverp.h>
23 #endif
24 #ifdef __APPLE__
25   #include <mach-o/dyld.h>
26 #endif
27 #ifdef _AIX
28 #include <dlfcn.h>
29 #include <sys/debug.h>
30 #include <sys/pseg.h>
31 #endif
32 
33 #if defined(_LIBUNWIND_TARGET_LINUX) &&                                        \
34     (defined(_LIBUNWIND_TARGET_AARCH64) || defined(_LIBUNWIND_TARGET_S390X))
35 #include <sys/syscall.h>
36 #include <sys/uio.h>
37 #include <unistd.h>
38 #define _LIBUNWIND_CHECK_LINUX_SIGRETURN 1
39 #endif
40 
41 #if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
42 // Provide a definition for the DISPATCHER_CONTEXT struct for old (Win7 and
43 // earlier) SDKs.
44 // MinGW-w64 has always provided this struct.
45   #if defined(_WIN32) && defined(_LIBUNWIND_TARGET_X86_64) && \
46       !defined(__MINGW32__) && VER_PRODUCTBUILD < 8000
47 struct _DISPATCHER_CONTEXT {
48   ULONG64 ControlPc;
49   ULONG64 ImageBase;
50   PRUNTIME_FUNCTION FunctionEntry;
51   ULONG64 EstablisherFrame;
52   ULONG64 TargetIp;
53   PCONTEXT ContextRecord;
54   PEXCEPTION_ROUTINE LanguageHandler;
55   PVOID HandlerData;
56   PUNWIND_HISTORY_TABLE HistoryTable;
57   ULONG ScopeIndex;
58   ULONG Fill0;
59 };
60   #endif
61 
62 struct UNWIND_INFO {
63   uint8_t Version : 3;
64   uint8_t Flags : 5;
65   uint8_t SizeOfProlog;
66   uint8_t CountOfCodes;
67   uint8_t FrameRegister : 4;
68   uint8_t FrameOffset : 4;
69   uint16_t UnwindCodes[2];
70 };
71 
72 extern "C" _Unwind_Reason_Code __libunwind_seh_personality(
73     int, _Unwind_Action, uint64_t, _Unwind_Exception *,
74     struct _Unwind_Context *);
75 
76 #endif
77 
78 #include "config.h"
79 
80 #include "AddressSpace.hpp"
81 #include "CompactUnwinder.hpp"
82 #include "config.h"
83 #include "DwarfInstructions.hpp"
84 #include "EHHeaderParser.hpp"
85 #include "libunwind.h"
86 #include "Registers.hpp"
87 #include "RWMutex.hpp"
88 #include "Unwind-EHABI.h"
89 
90 namespace libunwind {
91 
92 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
93 /// Cache of recently found FDEs.
94 template <typename A>
95 class _LIBUNWIND_HIDDEN DwarfFDECache {
96   typedef typename A::pint_t pint_t;
97 public:
98   static constexpr pint_t kSearchAll = static_cast<pint_t>(-1);
99   static pint_t findFDE(pint_t mh, pint_t pc);
100   static void add(pint_t mh, pint_t ip_start, pint_t ip_end, pint_t fde);
101   static void removeAllIn(pint_t mh);
102   static void iterateCacheEntries(void (*func)(unw_word_t ip_start,
103                                                unw_word_t ip_end,
104                                                unw_word_t fde, unw_word_t mh));
105 
106 private:
107 
108   struct entry {
109     pint_t mh;
110     pint_t ip_start;
111     pint_t ip_end;
112     pint_t fde;
113   };
114 
115   // These fields are all static to avoid needing an initializer.
116   // There is only one instance of this class per process.
117   static RWMutex _lock;
118 #ifdef __APPLE__
119   static void dyldUnloadHook(const struct mach_header *mh, intptr_t slide);
120   static bool _registeredForDyldUnloads;
121 #endif
122   static entry *_buffer;
123   static entry *_bufferUsed;
124   static entry *_bufferEnd;
125   static entry _initialBuffer[64];
126 };
127 
128 template <typename A>
129 typename DwarfFDECache<A>::entry *
130 DwarfFDECache<A>::_buffer = _initialBuffer;
131 
132 template <typename A>
133 typename DwarfFDECache<A>::entry *
134 DwarfFDECache<A>::_bufferUsed = _initialBuffer;
135 
136 template <typename A>
137 typename DwarfFDECache<A>::entry *
138 DwarfFDECache<A>::_bufferEnd = &_initialBuffer[64];
139 
140 template <typename A>
141 typename DwarfFDECache<A>::entry DwarfFDECache<A>::_initialBuffer[64];
142 
143 template <typename A>
144 RWMutex DwarfFDECache<A>::_lock;
145 
146 #ifdef __APPLE__
147 template <typename A>
148 bool DwarfFDECache<A>::_registeredForDyldUnloads = false;
149 #endif
150 
151 template <typename A>
152 typename A::pint_t DwarfFDECache<A>::findFDE(pint_t mh, pint_t pc) {
153   pint_t result = 0;
154   _LIBUNWIND_LOG_IF_FALSE(_lock.lock_shared());
155   for (entry *p = _buffer; p < _bufferUsed; ++p) {
156     if ((mh == p->mh) || (mh == kSearchAll)) {
157       if ((p->ip_start <= pc) && (pc < p->ip_end)) {
158         result = p->fde;
159         break;
160       }
161     }
162   }
163   _LIBUNWIND_LOG_IF_FALSE(_lock.unlock_shared());
164   return result;
165 }
166 
167 template <typename A>
168 void DwarfFDECache<A>::add(pint_t mh, pint_t ip_start, pint_t ip_end,
169                            pint_t fde) {
170 #if !defined(_LIBUNWIND_NO_HEAP)
171   _LIBUNWIND_LOG_IF_FALSE(_lock.lock());
172   if (_bufferUsed >= _bufferEnd) {
173     size_t oldSize = (size_t)(_bufferEnd - _buffer);
174     size_t newSize = oldSize * 4;
175     // Can't use operator new (we are below it).
176     entry *newBuffer = (entry *)malloc(newSize * sizeof(entry));
177     memcpy(newBuffer, _buffer, oldSize * sizeof(entry));
178     if (_buffer != _initialBuffer)
179       free(_buffer);
180     _buffer = newBuffer;
181     _bufferUsed = &newBuffer[oldSize];
182     _bufferEnd = &newBuffer[newSize];
183   }
184   _bufferUsed->mh = mh;
185   _bufferUsed->ip_start = ip_start;
186   _bufferUsed->ip_end = ip_end;
187   _bufferUsed->fde = fde;
188   ++_bufferUsed;
189 #ifdef __APPLE__
190   if (!_registeredForDyldUnloads) {
191     _dyld_register_func_for_remove_image(&dyldUnloadHook);
192     _registeredForDyldUnloads = true;
193   }
194 #endif
195   _LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
196 #endif
197 }
198 
199 template <typename A>
200 void DwarfFDECache<A>::removeAllIn(pint_t mh) {
201   _LIBUNWIND_LOG_IF_FALSE(_lock.lock());
202   entry *d = _buffer;
203   for (const entry *s = _buffer; s < _bufferUsed; ++s) {
204     if (s->mh != mh) {
205       if (d != s)
206         *d = *s;
207       ++d;
208     }
209   }
210   _bufferUsed = d;
211   _LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
212 }
213 
214 #ifdef __APPLE__
215 template <typename A>
216 void DwarfFDECache<A>::dyldUnloadHook(const struct mach_header *mh, intptr_t ) {
217   removeAllIn((pint_t) mh);
218 }
219 #endif
220 
221 template <typename A>
222 void DwarfFDECache<A>::iterateCacheEntries(void (*func)(
223     unw_word_t ip_start, unw_word_t ip_end, unw_word_t fde, unw_word_t mh)) {
224   _LIBUNWIND_LOG_IF_FALSE(_lock.lock());
225   for (entry *p = _buffer; p < _bufferUsed; ++p) {
226     (*func)(p->ip_start, p->ip_end, p->fde, p->mh);
227   }
228   _LIBUNWIND_LOG_IF_FALSE(_lock.unlock());
229 }
230 #endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
231 
232 
233 #define arrayoffsetof(type, index, field) ((size_t)(&((type *)0)[index].field))
234 
235 #if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
236 template <typename A> class UnwindSectionHeader {
237 public:
238   UnwindSectionHeader(A &addressSpace, typename A::pint_t addr)
239       : _addressSpace(addressSpace), _addr(addr) {}
240 
241   uint32_t version() const {
242     return _addressSpace.get32(_addr +
243                                offsetof(unwind_info_section_header, version));
244   }
245   uint32_t commonEncodingsArraySectionOffset() const {
246     return _addressSpace.get32(_addr +
247                                offsetof(unwind_info_section_header,
248                                         commonEncodingsArraySectionOffset));
249   }
250   uint32_t commonEncodingsArrayCount() const {
251     return _addressSpace.get32(_addr + offsetof(unwind_info_section_header,
252                                                 commonEncodingsArrayCount));
253   }
254   uint32_t personalityArraySectionOffset() const {
255     return _addressSpace.get32(_addr + offsetof(unwind_info_section_header,
256                                                 personalityArraySectionOffset));
257   }
258   uint32_t personalityArrayCount() const {
259     return _addressSpace.get32(
260         _addr + offsetof(unwind_info_section_header, personalityArrayCount));
261   }
262   uint32_t indexSectionOffset() const {
263     return _addressSpace.get32(
264         _addr + offsetof(unwind_info_section_header, indexSectionOffset));
265   }
266   uint32_t indexCount() const {
267     return _addressSpace.get32(
268         _addr + offsetof(unwind_info_section_header, indexCount));
269   }
270 
271 private:
272   A                     &_addressSpace;
273   typename A::pint_t     _addr;
274 };
275 
276 template <typename A> class UnwindSectionIndexArray {
277 public:
278   UnwindSectionIndexArray(A &addressSpace, typename A::pint_t addr)
279       : _addressSpace(addressSpace), _addr(addr) {}
280 
281   uint32_t functionOffset(uint32_t index) const {
282     return _addressSpace.get32(
283         _addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
284                               functionOffset));
285   }
286   uint32_t secondLevelPagesSectionOffset(uint32_t index) const {
287     return _addressSpace.get32(
288         _addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
289                               secondLevelPagesSectionOffset));
290   }
291   uint32_t lsdaIndexArraySectionOffset(uint32_t index) const {
292     return _addressSpace.get32(
293         _addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
294                               lsdaIndexArraySectionOffset));
295   }
296 
297 private:
298   A                   &_addressSpace;
299   typename A::pint_t   _addr;
300 };
301 
302 template <typename A> class UnwindSectionRegularPageHeader {
303 public:
304   UnwindSectionRegularPageHeader(A &addressSpace, typename A::pint_t addr)
305       : _addressSpace(addressSpace), _addr(addr) {}
306 
307   uint32_t kind() const {
308     return _addressSpace.get32(
309         _addr + offsetof(unwind_info_regular_second_level_page_header, kind));
310   }
311   uint16_t entryPageOffset() const {
312     return _addressSpace.get16(
313         _addr + offsetof(unwind_info_regular_second_level_page_header,
314                          entryPageOffset));
315   }
316   uint16_t entryCount() const {
317     return _addressSpace.get16(
318         _addr +
319         offsetof(unwind_info_regular_second_level_page_header, entryCount));
320   }
321 
322 private:
323   A &_addressSpace;
324   typename A::pint_t _addr;
325 };
326 
327 template <typename A> class UnwindSectionRegularArray {
328 public:
329   UnwindSectionRegularArray(A &addressSpace, typename A::pint_t addr)
330       : _addressSpace(addressSpace), _addr(addr) {}
331 
332   uint32_t functionOffset(uint32_t index) const {
333     return _addressSpace.get32(
334         _addr + arrayoffsetof(unwind_info_regular_second_level_entry, index,
335                               functionOffset));
336   }
337   uint32_t encoding(uint32_t index) const {
338     return _addressSpace.get32(
339         _addr +
340         arrayoffsetof(unwind_info_regular_second_level_entry, index, encoding));
341   }
342 
343 private:
344   A &_addressSpace;
345   typename A::pint_t _addr;
346 };
347 
348 template <typename A> class UnwindSectionCompressedPageHeader {
349 public:
350   UnwindSectionCompressedPageHeader(A &addressSpace, typename A::pint_t addr)
351       : _addressSpace(addressSpace), _addr(addr) {}
352 
353   uint32_t kind() const {
354     return _addressSpace.get32(
355         _addr +
356         offsetof(unwind_info_compressed_second_level_page_header, kind));
357   }
358   uint16_t entryPageOffset() const {
359     return _addressSpace.get16(
360         _addr + offsetof(unwind_info_compressed_second_level_page_header,
361                          entryPageOffset));
362   }
363   uint16_t entryCount() const {
364     return _addressSpace.get16(
365         _addr +
366         offsetof(unwind_info_compressed_second_level_page_header, entryCount));
367   }
368   uint16_t encodingsPageOffset() const {
369     return _addressSpace.get16(
370         _addr + offsetof(unwind_info_compressed_second_level_page_header,
371                          encodingsPageOffset));
372   }
373   uint16_t encodingsCount() const {
374     return _addressSpace.get16(
375         _addr + offsetof(unwind_info_compressed_second_level_page_header,
376                          encodingsCount));
377   }
378 
379 private:
380   A &_addressSpace;
381   typename A::pint_t _addr;
382 };
383 
384 template <typename A> class UnwindSectionCompressedArray {
385 public:
386   UnwindSectionCompressedArray(A &addressSpace, typename A::pint_t addr)
387       : _addressSpace(addressSpace), _addr(addr) {}
388 
389   uint32_t functionOffset(uint32_t index) const {
390     return UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET(
391         _addressSpace.get32(_addr + index * sizeof(uint32_t)));
392   }
393   uint16_t encodingIndex(uint32_t index) const {
394     return UNWIND_INFO_COMPRESSED_ENTRY_ENCODING_INDEX(
395         _addressSpace.get32(_addr + index * sizeof(uint32_t)));
396   }
397 
398 private:
399   A &_addressSpace;
400   typename A::pint_t _addr;
401 };
402 
403 template <typename A> class UnwindSectionLsdaArray {
404 public:
405   UnwindSectionLsdaArray(A &addressSpace, typename A::pint_t addr)
406       : _addressSpace(addressSpace), _addr(addr) {}
407 
408   uint32_t functionOffset(uint32_t index) const {
409     return _addressSpace.get32(
410         _addr + arrayoffsetof(unwind_info_section_header_lsda_index_entry,
411                               index, functionOffset));
412   }
413   uint32_t lsdaOffset(uint32_t index) const {
414     return _addressSpace.get32(
415         _addr + arrayoffsetof(unwind_info_section_header_lsda_index_entry,
416                               index, lsdaOffset));
417   }
418 
419 private:
420   A                   &_addressSpace;
421   typename A::pint_t   _addr;
422 };
423 #endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
424 
425 class _LIBUNWIND_HIDDEN AbstractUnwindCursor {
426 public:
427   // NOTE: provide a class specific placement deallocation function (S5.3.4 p20)
428   // This avoids an unnecessary dependency to libc++abi.
429   void operator delete(void *, size_t) {}
430 
431   virtual ~AbstractUnwindCursor() {}
432   virtual bool validReg(int) { _LIBUNWIND_ABORT("validReg not implemented"); }
433   virtual unw_word_t getReg(int) { _LIBUNWIND_ABORT("getReg not implemented"); }
434   virtual void setReg(int, unw_word_t) {
435     _LIBUNWIND_ABORT("setReg not implemented");
436   }
437   virtual bool validFloatReg(int) {
438     _LIBUNWIND_ABORT("validFloatReg not implemented");
439   }
440   virtual unw_fpreg_t getFloatReg(int) {
441     _LIBUNWIND_ABORT("getFloatReg not implemented");
442   }
443   virtual void setFloatReg(int, unw_fpreg_t) {
444     _LIBUNWIND_ABORT("setFloatReg not implemented");
445   }
446   virtual int step() { _LIBUNWIND_ABORT("step not implemented"); }
447   virtual void getInfo(unw_proc_info_t *) {
448     _LIBUNWIND_ABORT("getInfo not implemented");
449   }
450   virtual void jumpto() { _LIBUNWIND_ABORT("jumpto not implemented"); }
451   virtual bool isSignalFrame() {
452     _LIBUNWIND_ABORT("isSignalFrame not implemented");
453   }
454   virtual bool getFunctionName(char *, size_t, unw_word_t *) {
455     _LIBUNWIND_ABORT("getFunctionName not implemented");
456   }
457   virtual void setInfoBasedOnIPRegister(bool = false) {
458     _LIBUNWIND_ABORT("setInfoBasedOnIPRegister not implemented");
459   }
460   virtual const char *getRegisterName(int) {
461     _LIBUNWIND_ABORT("getRegisterName not implemented");
462   }
463 #ifdef __arm__
464   virtual void saveVFPAsX() { _LIBUNWIND_ABORT("saveVFPAsX not implemented"); }
465 #endif
466 
467 #ifdef _AIX
468   virtual uintptr_t getDataRelBase() {
469     _LIBUNWIND_ABORT("getDataRelBase not implemented");
470   }
471 #endif
472 
473 #if defined(_LIBUNWIND_USE_CET)
474   virtual void *get_registers() {
475     _LIBUNWIND_ABORT("get_registers not implemented");
476   }
477 #endif
478 };
479 
480 #if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) && defined(_WIN32)
481 
482 /// \c UnwindCursor contains all state (including all register values) during
483 /// an unwind.  This is normally stack-allocated inside a unw_cursor_t.
484 template <typename A, typename R>
485 class UnwindCursor : public AbstractUnwindCursor {
486   typedef typename A::pint_t pint_t;
487 public:
488                       UnwindCursor(unw_context_t *context, A &as);
489                       UnwindCursor(CONTEXT *context, A &as);
490                       UnwindCursor(A &as, void *threadArg);
491   virtual             ~UnwindCursor() {}
492   virtual bool        validReg(int);
493   virtual unw_word_t  getReg(int);
494   virtual void        setReg(int, unw_word_t);
495   virtual bool        validFloatReg(int);
496   virtual unw_fpreg_t getFloatReg(int);
497   virtual void        setFloatReg(int, unw_fpreg_t);
498   virtual int         step();
499   virtual void        getInfo(unw_proc_info_t *);
500   virtual void        jumpto();
501   virtual bool        isSignalFrame();
502   virtual bool        getFunctionName(char *buf, size_t len, unw_word_t *off);
503   virtual void        setInfoBasedOnIPRegister(bool isReturnAddress = false);
504   virtual const char *getRegisterName(int num);
505 #ifdef __arm__
506   virtual void        saveVFPAsX();
507 #endif
508 
509   DISPATCHER_CONTEXT *getDispatcherContext() { return &_dispContext; }
510   void setDispatcherContext(DISPATCHER_CONTEXT *disp) { _dispContext = *disp; }
511 
512   // libunwind does not and should not depend on C++ library which means that we
513   // need our own defition of inline placement new.
514   static void *operator new(size_t, UnwindCursor<A, R> *p) { return p; }
515 
516 private:
517 
518   pint_t getLastPC() const { return _dispContext.ControlPc; }
519   void setLastPC(pint_t pc) { _dispContext.ControlPc = pc; }
520   RUNTIME_FUNCTION *lookUpSEHUnwindInfo(pint_t pc, pint_t *base) {
521 #ifdef __arm__
522     // Remove the thumb bit; FunctionEntry ranges don't include the thumb bit.
523     pc &= ~1U;
524 #endif
525     // If pc points exactly at the end of the range, we might resolve the
526     // next function instead. Decrement pc by 1 to fit inside the current
527     // function.
528     pc -= 1;
529     _dispContext.FunctionEntry = RtlLookupFunctionEntry(pc,
530                                                         &_dispContext.ImageBase,
531                                                         _dispContext.HistoryTable);
532     *base = _dispContext.ImageBase;
533     return _dispContext.FunctionEntry;
534   }
535   bool getInfoFromSEH(pint_t pc);
536   int stepWithSEHData() {
537     _dispContext.LanguageHandler = RtlVirtualUnwind(UNW_FLAG_UHANDLER,
538                                                     _dispContext.ImageBase,
539                                                     _dispContext.ControlPc,
540                                                     _dispContext.FunctionEntry,
541                                                     _dispContext.ContextRecord,
542                                                     &_dispContext.HandlerData,
543                                                     &_dispContext.EstablisherFrame,
544                                                     NULL);
545     // Update some fields of the unwind info now, since we have them.
546     _info.lsda = reinterpret_cast<unw_word_t>(_dispContext.HandlerData);
547     if (_dispContext.LanguageHandler) {
548       _info.handler = reinterpret_cast<unw_word_t>(__libunwind_seh_personality);
549     } else
550       _info.handler = 0;
551     return UNW_STEP_SUCCESS;
552   }
553 
554   A                   &_addressSpace;
555   unw_proc_info_t      _info;
556   DISPATCHER_CONTEXT   _dispContext;
557   CONTEXT              _msContext;
558   UNWIND_HISTORY_TABLE _histTable;
559   bool                 _unwindInfoMissing;
560 };
561 
562 
563 template <typename A, typename R>
564 UnwindCursor<A, R>::UnwindCursor(unw_context_t *context, A &as)
565     : _addressSpace(as), _unwindInfoMissing(false) {
566   static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
567                 "UnwindCursor<> does not fit in unw_cursor_t");
568   static_assert((alignof(UnwindCursor<A, R>) <= alignof(unw_cursor_t)),
569                 "UnwindCursor<> requires more alignment than unw_cursor_t");
570   memset(&_info, 0, sizeof(_info));
571   memset(&_histTable, 0, sizeof(_histTable));
572   _dispContext.ContextRecord = &_msContext;
573   _dispContext.HistoryTable = &_histTable;
574   // Initialize MS context from ours.
575   R r(context);
576   _msContext.ContextFlags = CONTEXT_CONTROL|CONTEXT_INTEGER|CONTEXT_FLOATING_POINT;
577 #if defined(_LIBUNWIND_TARGET_X86_64)
578   _msContext.Rax = r.getRegister(UNW_X86_64_RAX);
579   _msContext.Rcx = r.getRegister(UNW_X86_64_RCX);
580   _msContext.Rdx = r.getRegister(UNW_X86_64_RDX);
581   _msContext.Rbx = r.getRegister(UNW_X86_64_RBX);
582   _msContext.Rsp = r.getRegister(UNW_X86_64_RSP);
583   _msContext.Rbp = r.getRegister(UNW_X86_64_RBP);
584   _msContext.Rsi = r.getRegister(UNW_X86_64_RSI);
585   _msContext.Rdi = r.getRegister(UNW_X86_64_RDI);
586   _msContext.R8 = r.getRegister(UNW_X86_64_R8);
587   _msContext.R9 = r.getRegister(UNW_X86_64_R9);
588   _msContext.R10 = r.getRegister(UNW_X86_64_R10);
589   _msContext.R11 = r.getRegister(UNW_X86_64_R11);
590   _msContext.R12 = r.getRegister(UNW_X86_64_R12);
591   _msContext.R13 = r.getRegister(UNW_X86_64_R13);
592   _msContext.R14 = r.getRegister(UNW_X86_64_R14);
593   _msContext.R15 = r.getRegister(UNW_X86_64_R15);
594   _msContext.Rip = r.getRegister(UNW_REG_IP);
595   union {
596     v128 v;
597     M128A m;
598   } t;
599   t.v = r.getVectorRegister(UNW_X86_64_XMM0);
600   _msContext.Xmm0 = t.m;
601   t.v = r.getVectorRegister(UNW_X86_64_XMM1);
602   _msContext.Xmm1 = t.m;
603   t.v = r.getVectorRegister(UNW_X86_64_XMM2);
604   _msContext.Xmm2 = t.m;
605   t.v = r.getVectorRegister(UNW_X86_64_XMM3);
606   _msContext.Xmm3 = t.m;
607   t.v = r.getVectorRegister(UNW_X86_64_XMM4);
608   _msContext.Xmm4 = t.m;
609   t.v = r.getVectorRegister(UNW_X86_64_XMM5);
610   _msContext.Xmm5 = t.m;
611   t.v = r.getVectorRegister(UNW_X86_64_XMM6);
612   _msContext.Xmm6 = t.m;
613   t.v = r.getVectorRegister(UNW_X86_64_XMM7);
614   _msContext.Xmm7 = t.m;
615   t.v = r.getVectorRegister(UNW_X86_64_XMM8);
616   _msContext.Xmm8 = t.m;
617   t.v = r.getVectorRegister(UNW_X86_64_XMM9);
618   _msContext.Xmm9 = t.m;
619   t.v = r.getVectorRegister(UNW_X86_64_XMM10);
620   _msContext.Xmm10 = t.m;
621   t.v = r.getVectorRegister(UNW_X86_64_XMM11);
622   _msContext.Xmm11 = t.m;
623   t.v = r.getVectorRegister(UNW_X86_64_XMM12);
624   _msContext.Xmm12 = t.m;
625   t.v = r.getVectorRegister(UNW_X86_64_XMM13);
626   _msContext.Xmm13 = t.m;
627   t.v = r.getVectorRegister(UNW_X86_64_XMM14);
628   _msContext.Xmm14 = t.m;
629   t.v = r.getVectorRegister(UNW_X86_64_XMM15);
630   _msContext.Xmm15 = t.m;
631 #elif defined(_LIBUNWIND_TARGET_ARM)
632   _msContext.R0 = r.getRegister(UNW_ARM_R0);
633   _msContext.R1 = r.getRegister(UNW_ARM_R1);
634   _msContext.R2 = r.getRegister(UNW_ARM_R2);
635   _msContext.R3 = r.getRegister(UNW_ARM_R3);
636   _msContext.R4 = r.getRegister(UNW_ARM_R4);
637   _msContext.R5 = r.getRegister(UNW_ARM_R5);
638   _msContext.R6 = r.getRegister(UNW_ARM_R6);
639   _msContext.R7 = r.getRegister(UNW_ARM_R7);
640   _msContext.R8 = r.getRegister(UNW_ARM_R8);
641   _msContext.R9 = r.getRegister(UNW_ARM_R9);
642   _msContext.R10 = r.getRegister(UNW_ARM_R10);
643   _msContext.R11 = r.getRegister(UNW_ARM_R11);
644   _msContext.R12 = r.getRegister(UNW_ARM_R12);
645   _msContext.Sp = r.getRegister(UNW_ARM_SP);
646   _msContext.Lr = r.getRegister(UNW_ARM_LR);
647   _msContext.Pc = r.getRegister(UNW_ARM_IP);
648   for (int i = UNW_ARM_D0; i <= UNW_ARM_D31; ++i) {
649     union {
650       uint64_t w;
651       double d;
652     } d;
653     d.d = r.getFloatRegister(i);
654     _msContext.D[i - UNW_ARM_D0] = d.w;
655   }
656 #elif defined(_LIBUNWIND_TARGET_AARCH64)
657   for (int i = UNW_AARCH64_X0; i <= UNW_ARM64_X30; ++i)
658     _msContext.X[i - UNW_AARCH64_X0] = r.getRegister(i);
659   _msContext.Sp = r.getRegister(UNW_REG_SP);
660   _msContext.Pc = r.getRegister(UNW_REG_IP);
661   for (int i = UNW_AARCH64_V0; i <= UNW_ARM64_D31; ++i)
662     _msContext.V[i - UNW_AARCH64_V0].D[0] = r.getFloatRegister(i);
663 #endif
664 }
665 
666 template <typename A, typename R>
667 UnwindCursor<A, R>::UnwindCursor(CONTEXT *context, A &as)
668     : _addressSpace(as), _unwindInfoMissing(false) {
669   static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
670                 "UnwindCursor<> does not fit in unw_cursor_t");
671   memset(&_info, 0, sizeof(_info));
672   memset(&_histTable, 0, sizeof(_histTable));
673   _dispContext.ContextRecord = &_msContext;
674   _dispContext.HistoryTable = &_histTable;
675   _msContext = *context;
676 }
677 
678 
679 template <typename A, typename R>
680 bool UnwindCursor<A, R>::validReg(int regNum) {
681   if (regNum == UNW_REG_IP || regNum == UNW_REG_SP) return true;
682 #if defined(_LIBUNWIND_TARGET_X86_64)
683   if (regNum >= UNW_X86_64_RAX && regNum <= UNW_X86_64_R15) return true;
684 #elif defined(_LIBUNWIND_TARGET_ARM)
685   if ((regNum >= UNW_ARM_R0 && regNum <= UNW_ARM_R15) ||
686       regNum == UNW_ARM_RA_AUTH_CODE)
687     return true;
688 #elif defined(_LIBUNWIND_TARGET_AARCH64)
689   if (regNum >= UNW_AARCH64_X0 && regNum <= UNW_ARM64_X30) return true;
690 #endif
691   return false;
692 }
693 
694 template <typename A, typename R>
695 unw_word_t UnwindCursor<A, R>::getReg(int regNum) {
696   switch (regNum) {
697 #if defined(_LIBUNWIND_TARGET_X86_64)
698   case UNW_REG_IP: return _msContext.Rip;
699   case UNW_X86_64_RAX: return _msContext.Rax;
700   case UNW_X86_64_RDX: return _msContext.Rdx;
701   case UNW_X86_64_RCX: return _msContext.Rcx;
702   case UNW_X86_64_RBX: return _msContext.Rbx;
703   case UNW_REG_SP:
704   case UNW_X86_64_RSP: return _msContext.Rsp;
705   case UNW_X86_64_RBP: return _msContext.Rbp;
706   case UNW_X86_64_RSI: return _msContext.Rsi;
707   case UNW_X86_64_RDI: return _msContext.Rdi;
708   case UNW_X86_64_R8: return _msContext.R8;
709   case UNW_X86_64_R9: return _msContext.R9;
710   case UNW_X86_64_R10: return _msContext.R10;
711   case UNW_X86_64_R11: return _msContext.R11;
712   case UNW_X86_64_R12: return _msContext.R12;
713   case UNW_X86_64_R13: return _msContext.R13;
714   case UNW_X86_64_R14: return _msContext.R14;
715   case UNW_X86_64_R15: return _msContext.R15;
716 #elif defined(_LIBUNWIND_TARGET_ARM)
717   case UNW_ARM_R0: return _msContext.R0;
718   case UNW_ARM_R1: return _msContext.R1;
719   case UNW_ARM_R2: return _msContext.R2;
720   case UNW_ARM_R3: return _msContext.R3;
721   case UNW_ARM_R4: return _msContext.R4;
722   case UNW_ARM_R5: return _msContext.R5;
723   case UNW_ARM_R6: return _msContext.R6;
724   case UNW_ARM_R7: return _msContext.R7;
725   case UNW_ARM_R8: return _msContext.R8;
726   case UNW_ARM_R9: return _msContext.R9;
727   case UNW_ARM_R10: return _msContext.R10;
728   case UNW_ARM_R11: return _msContext.R11;
729   case UNW_ARM_R12: return _msContext.R12;
730   case UNW_REG_SP:
731   case UNW_ARM_SP: return _msContext.Sp;
732   case UNW_ARM_LR: return _msContext.Lr;
733   case UNW_REG_IP:
734   case UNW_ARM_IP: return _msContext.Pc;
735 #elif defined(_LIBUNWIND_TARGET_AARCH64)
736   case UNW_REG_SP: return _msContext.Sp;
737   case UNW_REG_IP: return _msContext.Pc;
738   default: return _msContext.X[regNum - UNW_AARCH64_X0];
739 #endif
740   }
741   _LIBUNWIND_ABORT("unsupported register");
742 }
743 
744 template <typename A, typename R>
745 void UnwindCursor<A, R>::setReg(int regNum, unw_word_t value) {
746   switch (regNum) {
747 #if defined(_LIBUNWIND_TARGET_X86_64)
748   case UNW_REG_IP: _msContext.Rip = value; break;
749   case UNW_X86_64_RAX: _msContext.Rax = value; break;
750   case UNW_X86_64_RDX: _msContext.Rdx = value; break;
751   case UNW_X86_64_RCX: _msContext.Rcx = value; break;
752   case UNW_X86_64_RBX: _msContext.Rbx = value; break;
753   case UNW_REG_SP:
754   case UNW_X86_64_RSP: _msContext.Rsp = value; break;
755   case UNW_X86_64_RBP: _msContext.Rbp = value; break;
756   case UNW_X86_64_RSI: _msContext.Rsi = value; break;
757   case UNW_X86_64_RDI: _msContext.Rdi = value; break;
758   case UNW_X86_64_R8: _msContext.R8 = value; break;
759   case UNW_X86_64_R9: _msContext.R9 = value; break;
760   case UNW_X86_64_R10: _msContext.R10 = value; break;
761   case UNW_X86_64_R11: _msContext.R11 = value; break;
762   case UNW_X86_64_R12: _msContext.R12 = value; break;
763   case UNW_X86_64_R13: _msContext.R13 = value; break;
764   case UNW_X86_64_R14: _msContext.R14 = value; break;
765   case UNW_X86_64_R15: _msContext.R15 = value; break;
766 #elif defined(_LIBUNWIND_TARGET_ARM)
767   case UNW_ARM_R0: _msContext.R0 = value; break;
768   case UNW_ARM_R1: _msContext.R1 = value; break;
769   case UNW_ARM_R2: _msContext.R2 = value; break;
770   case UNW_ARM_R3: _msContext.R3 = value; break;
771   case UNW_ARM_R4: _msContext.R4 = value; break;
772   case UNW_ARM_R5: _msContext.R5 = value; break;
773   case UNW_ARM_R6: _msContext.R6 = value; break;
774   case UNW_ARM_R7: _msContext.R7 = value; break;
775   case UNW_ARM_R8: _msContext.R8 = value; break;
776   case UNW_ARM_R9: _msContext.R9 = value; break;
777   case UNW_ARM_R10: _msContext.R10 = value; break;
778   case UNW_ARM_R11: _msContext.R11 = value; break;
779   case UNW_ARM_R12: _msContext.R12 = value; break;
780   case UNW_REG_SP:
781   case UNW_ARM_SP: _msContext.Sp = value; break;
782   case UNW_ARM_LR: _msContext.Lr = value; break;
783   case UNW_REG_IP:
784   case UNW_ARM_IP: _msContext.Pc = value; break;
785 #elif defined(_LIBUNWIND_TARGET_AARCH64)
786   case UNW_REG_SP: _msContext.Sp = value; break;
787   case UNW_REG_IP: _msContext.Pc = value; break;
788   case UNW_AARCH64_X0:
789   case UNW_AARCH64_X1:
790   case UNW_AARCH64_X2:
791   case UNW_AARCH64_X3:
792   case UNW_AARCH64_X4:
793   case UNW_AARCH64_X5:
794   case UNW_AARCH64_X6:
795   case UNW_AARCH64_X7:
796   case UNW_AARCH64_X8:
797   case UNW_AARCH64_X9:
798   case UNW_AARCH64_X10:
799   case UNW_AARCH64_X11:
800   case UNW_AARCH64_X12:
801   case UNW_AARCH64_X13:
802   case UNW_AARCH64_X14:
803   case UNW_AARCH64_X15:
804   case UNW_AARCH64_X16:
805   case UNW_AARCH64_X17:
806   case UNW_AARCH64_X18:
807   case UNW_AARCH64_X19:
808   case UNW_AARCH64_X20:
809   case UNW_AARCH64_X21:
810   case UNW_AARCH64_X22:
811   case UNW_AARCH64_X23:
812   case UNW_AARCH64_X24:
813   case UNW_AARCH64_X25:
814   case UNW_AARCH64_X26:
815   case UNW_AARCH64_X27:
816   case UNW_AARCH64_X28:
817   case UNW_AARCH64_FP:
818   case UNW_AARCH64_LR: _msContext.X[regNum - UNW_ARM64_X0] = value; break;
819 #endif
820   default:
821     _LIBUNWIND_ABORT("unsupported register");
822   }
823 }
824 
825 template <typename A, typename R>
826 bool UnwindCursor<A, R>::validFloatReg(int regNum) {
827 #if defined(_LIBUNWIND_TARGET_ARM)
828   if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) return true;
829   if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) return true;
830 #elif defined(_LIBUNWIND_TARGET_AARCH64)
831   if (regNum >= UNW_AARCH64_V0 && regNum <= UNW_ARM64_D31) return true;
832 #else
833   (void)regNum;
834 #endif
835   return false;
836 }
837 
838 template <typename A, typename R>
839 unw_fpreg_t UnwindCursor<A, R>::getFloatReg(int regNum) {
840 #if defined(_LIBUNWIND_TARGET_ARM)
841   if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) {
842     union {
843       uint32_t w;
844       float f;
845     } d;
846     d.w = _msContext.S[regNum - UNW_ARM_S0];
847     return d.f;
848   }
849   if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) {
850     union {
851       uint64_t w;
852       double d;
853     } d;
854     d.w = _msContext.D[regNum - UNW_ARM_D0];
855     return d.d;
856   }
857   _LIBUNWIND_ABORT("unsupported float register");
858 #elif defined(_LIBUNWIND_TARGET_AARCH64)
859   return _msContext.V[regNum - UNW_AARCH64_V0].D[0];
860 #else
861   (void)regNum;
862   _LIBUNWIND_ABORT("float registers unimplemented");
863 #endif
864 }
865 
866 template <typename A, typename R>
867 void UnwindCursor<A, R>::setFloatReg(int regNum, unw_fpreg_t value) {
868 #if defined(_LIBUNWIND_TARGET_ARM)
869   if (regNum >= UNW_ARM_S0 && regNum <= UNW_ARM_S31) {
870     union {
871       uint32_t w;
872       float f;
873     } d;
874     d.f = (float)value;
875     _msContext.S[regNum - UNW_ARM_S0] = d.w;
876   }
877   if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D31) {
878     union {
879       uint64_t w;
880       double d;
881     } d;
882     d.d = value;
883     _msContext.D[regNum - UNW_ARM_D0] = d.w;
884   }
885   _LIBUNWIND_ABORT("unsupported float register");
886 #elif defined(_LIBUNWIND_TARGET_AARCH64)
887   _msContext.V[regNum - UNW_AARCH64_V0].D[0] = value;
888 #else
889   (void)regNum;
890   (void)value;
891   _LIBUNWIND_ABORT("float registers unimplemented");
892 #endif
893 }
894 
895 template <typename A, typename R> void UnwindCursor<A, R>::jumpto() {
896   RtlRestoreContext(&_msContext, nullptr);
897 }
898 
899 #ifdef __arm__
900 template <typename A, typename R> void UnwindCursor<A, R>::saveVFPAsX() {}
901 #endif
902 
903 template <typename A, typename R>
904 const char *UnwindCursor<A, R>::getRegisterName(int regNum) {
905   return R::getRegisterName(regNum);
906 }
907 
908 template <typename A, typename R> bool UnwindCursor<A, R>::isSignalFrame() {
909   return false;
910 }
911 
912 #else  // !defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) || !defined(_WIN32)
913 
914 /// UnwindCursor contains all state (including all register values) during
915 /// an unwind.  This is normally stack allocated inside a unw_cursor_t.
916 template <typename A, typename R>
917 class UnwindCursor : public AbstractUnwindCursor{
918   typedef typename A::pint_t pint_t;
919 public:
920                       UnwindCursor(unw_context_t *context, A &as);
921                       UnwindCursor(A &as, void *threadArg);
922   virtual             ~UnwindCursor() {}
923   virtual bool        validReg(int);
924   virtual unw_word_t  getReg(int);
925   virtual void        setReg(int, unw_word_t);
926   virtual bool        validFloatReg(int);
927   virtual unw_fpreg_t getFloatReg(int);
928   virtual void        setFloatReg(int, unw_fpreg_t);
929   virtual int         step();
930   virtual void        getInfo(unw_proc_info_t *);
931   virtual void        jumpto();
932   virtual bool        isSignalFrame();
933   virtual bool        getFunctionName(char *buf, size_t len, unw_word_t *off);
934   virtual void        setInfoBasedOnIPRegister(bool isReturnAddress = false);
935   virtual const char *getRegisterName(int num);
936 #ifdef __arm__
937   virtual void        saveVFPAsX();
938 #endif
939 
940 #ifdef _AIX
941   virtual uintptr_t getDataRelBase();
942 #endif
943 
944 #if defined(_LIBUNWIND_USE_CET)
945   virtual void *get_registers() { return &_registers; }
946 #endif
947 
948   // libunwind does not and should not depend on C++ library which means that we
949   // need our own defition of inline placement new.
950   static void *operator new(size_t, UnwindCursor<A, R> *p) { return p; }
951 
952 private:
953 
954 #if defined(_LIBUNWIND_ARM_EHABI)
955   bool getInfoFromEHABISection(pint_t pc, const UnwindInfoSections &sects);
956 
957   int stepWithEHABI() {
958     size_t len = 0;
959     size_t off = 0;
960     // FIXME: Calling decode_eht_entry() here is violating the libunwind
961     // abstraction layer.
962     const uint32_t *ehtp =
963         decode_eht_entry(reinterpret_cast<const uint32_t *>(_info.unwind_info),
964                          &off, &len);
965     if (_Unwind_VRS_Interpret((_Unwind_Context *)this, ehtp, off, len) !=
966             _URC_CONTINUE_UNWIND)
967       return UNW_STEP_END;
968     return UNW_STEP_SUCCESS;
969   }
970 #endif
971 
972 #if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN)
973   bool setInfoForSigReturn() {
974     R dummy;
975     return setInfoForSigReturn(dummy);
976   }
977   int stepThroughSigReturn() {
978     R dummy;
979     return stepThroughSigReturn(dummy);
980   }
981 #if defined(_LIBUNWIND_TARGET_AARCH64)
982   bool setInfoForSigReturn(Registers_arm64 &);
983   int stepThroughSigReturn(Registers_arm64 &);
984 #endif
985 #if defined(_LIBUNWIND_TARGET_S390X)
986   bool setInfoForSigReturn(Registers_s390x &);
987   int stepThroughSigReturn(Registers_s390x &);
988 #endif
989   template <typename Registers> bool setInfoForSigReturn(Registers &) {
990     return false;
991   }
992   template <typename Registers> int stepThroughSigReturn(Registers &) {
993     return UNW_STEP_END;
994   }
995 #endif
996 
997 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
998   bool getInfoFromFdeCie(const typename CFI_Parser<A>::FDE_Info &fdeInfo,
999                          const typename CFI_Parser<A>::CIE_Info &cieInfo,
1000                          pint_t pc, uintptr_t dso_base);
1001   bool getInfoFromDwarfSection(pint_t pc, const UnwindInfoSections &sects,
1002                                             uint32_t fdeSectionOffsetHint=0);
1003   int stepWithDwarfFDE() {
1004     return DwarfInstructions<A, R>::stepWithDwarf(_addressSpace,
1005                                               (pint_t)this->getReg(UNW_REG_IP),
1006                                               (pint_t)_info.unwind_info,
1007                                               _registers, _isSignalFrame);
1008   }
1009 #endif
1010 
1011 #if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1012   bool getInfoFromCompactEncodingSection(pint_t pc,
1013                                             const UnwindInfoSections &sects);
1014   int stepWithCompactEncoding() {
1015   #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1016     if ( compactSaysUseDwarf() )
1017       return stepWithDwarfFDE();
1018   #endif
1019     R dummy;
1020     return stepWithCompactEncoding(dummy);
1021   }
1022 
1023 #if defined(_LIBUNWIND_TARGET_X86_64)
1024   int stepWithCompactEncoding(Registers_x86_64 &) {
1025     return CompactUnwinder_x86_64<A>::stepWithCompactEncoding(
1026         _info.format, _info.start_ip, _addressSpace, _registers);
1027   }
1028 #endif
1029 
1030 #if defined(_LIBUNWIND_TARGET_I386)
1031   int stepWithCompactEncoding(Registers_x86 &) {
1032     return CompactUnwinder_x86<A>::stepWithCompactEncoding(
1033         _info.format, (uint32_t)_info.start_ip, _addressSpace, _registers);
1034   }
1035 #endif
1036 
1037 #if defined(_LIBUNWIND_TARGET_PPC)
1038   int stepWithCompactEncoding(Registers_ppc &) {
1039     return UNW_EINVAL;
1040   }
1041 #endif
1042 
1043 #if defined(_LIBUNWIND_TARGET_PPC64)
1044   int stepWithCompactEncoding(Registers_ppc64 &) {
1045     return UNW_EINVAL;
1046   }
1047 #endif
1048 
1049 
1050 #if defined(_LIBUNWIND_TARGET_AARCH64)
1051   int stepWithCompactEncoding(Registers_arm64 &) {
1052     return CompactUnwinder_arm64<A>::stepWithCompactEncoding(
1053         _info.format, _info.start_ip, _addressSpace, _registers);
1054   }
1055 #endif
1056 
1057 #if defined(_LIBUNWIND_TARGET_MIPS_O32)
1058   int stepWithCompactEncoding(Registers_mips_o32 &) {
1059     return UNW_EINVAL;
1060   }
1061 #endif
1062 
1063 #if defined(_LIBUNWIND_TARGET_MIPS_NEWABI)
1064   int stepWithCompactEncoding(Registers_mips_newabi &) {
1065     return UNW_EINVAL;
1066   }
1067 #endif
1068 
1069 #if defined(_LIBUNWIND_TARGET_SPARC)
1070   int stepWithCompactEncoding(Registers_sparc &) { return UNW_EINVAL; }
1071 #endif
1072 
1073 #if defined(_LIBUNWIND_TARGET_SPARC64)
1074   int stepWithCompactEncoding(Registers_sparc64 &) { return UNW_EINVAL; }
1075 #endif
1076 
1077 #if defined (_LIBUNWIND_TARGET_RISCV)
1078   int stepWithCompactEncoding(Registers_riscv &) {
1079     return UNW_EINVAL;
1080   }
1081 #endif
1082 
1083   bool compactSaysUseDwarf(uint32_t *offset=NULL) const {
1084     R dummy;
1085     return compactSaysUseDwarf(dummy, offset);
1086   }
1087 
1088 #if defined(_LIBUNWIND_TARGET_X86_64)
1089   bool compactSaysUseDwarf(Registers_x86_64 &, uint32_t *offset) const {
1090     if ((_info.format & UNWIND_X86_64_MODE_MASK) == UNWIND_X86_64_MODE_DWARF) {
1091       if (offset)
1092         *offset = (_info.format & UNWIND_X86_64_DWARF_SECTION_OFFSET);
1093       return true;
1094     }
1095     return false;
1096   }
1097 #endif
1098 
1099 #if defined(_LIBUNWIND_TARGET_I386)
1100   bool compactSaysUseDwarf(Registers_x86 &, uint32_t *offset) const {
1101     if ((_info.format & UNWIND_X86_MODE_MASK) == UNWIND_X86_MODE_DWARF) {
1102       if (offset)
1103         *offset = (_info.format & UNWIND_X86_DWARF_SECTION_OFFSET);
1104       return true;
1105     }
1106     return false;
1107   }
1108 #endif
1109 
1110 #if defined(_LIBUNWIND_TARGET_PPC)
1111   bool compactSaysUseDwarf(Registers_ppc &, uint32_t *) const {
1112     return true;
1113   }
1114 #endif
1115 
1116 #if defined(_LIBUNWIND_TARGET_PPC64)
1117   bool compactSaysUseDwarf(Registers_ppc64 &, uint32_t *) const {
1118     return true;
1119   }
1120 #endif
1121 
1122 #if defined(_LIBUNWIND_TARGET_AARCH64)
1123   bool compactSaysUseDwarf(Registers_arm64 &, uint32_t *offset) const {
1124     if ((_info.format & UNWIND_ARM64_MODE_MASK) == UNWIND_ARM64_MODE_DWARF) {
1125       if (offset)
1126         *offset = (_info.format & UNWIND_ARM64_DWARF_SECTION_OFFSET);
1127       return true;
1128     }
1129     return false;
1130   }
1131 #endif
1132 
1133 #if defined(_LIBUNWIND_TARGET_MIPS_O32)
1134   bool compactSaysUseDwarf(Registers_mips_o32 &, uint32_t *) const {
1135     return true;
1136   }
1137 #endif
1138 
1139 #if defined(_LIBUNWIND_TARGET_MIPS_NEWABI)
1140   bool compactSaysUseDwarf(Registers_mips_newabi &, uint32_t *) const {
1141     return true;
1142   }
1143 #endif
1144 
1145 #if defined(_LIBUNWIND_TARGET_SPARC)
1146   bool compactSaysUseDwarf(Registers_sparc &, uint32_t *) const { return true; }
1147 #endif
1148 
1149 #if defined(_LIBUNWIND_TARGET_SPARC64)
1150   bool compactSaysUseDwarf(Registers_sparc64 &, uint32_t *) const {
1151     return true;
1152   }
1153 #endif
1154 
1155 #if defined (_LIBUNWIND_TARGET_RISCV)
1156   bool compactSaysUseDwarf(Registers_riscv &, uint32_t *) const {
1157     return true;
1158   }
1159 #endif
1160 
1161 #endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1162 
1163 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1164   compact_unwind_encoding_t dwarfEncoding() const {
1165     R dummy;
1166     return dwarfEncoding(dummy);
1167   }
1168 
1169 #if defined(_LIBUNWIND_TARGET_X86_64)
1170   compact_unwind_encoding_t dwarfEncoding(Registers_x86_64 &) const {
1171     return UNWIND_X86_64_MODE_DWARF;
1172   }
1173 #endif
1174 
1175 #if defined(_LIBUNWIND_TARGET_I386)
1176   compact_unwind_encoding_t dwarfEncoding(Registers_x86 &) const {
1177     return UNWIND_X86_MODE_DWARF;
1178   }
1179 #endif
1180 
1181 #if defined(_LIBUNWIND_TARGET_PPC)
1182   compact_unwind_encoding_t dwarfEncoding(Registers_ppc &) const {
1183     return 0;
1184   }
1185 #endif
1186 
1187 #if defined(_LIBUNWIND_TARGET_PPC64)
1188   compact_unwind_encoding_t dwarfEncoding(Registers_ppc64 &) const {
1189     return 0;
1190   }
1191 #endif
1192 
1193 #if defined(_LIBUNWIND_TARGET_AARCH64)
1194   compact_unwind_encoding_t dwarfEncoding(Registers_arm64 &) const {
1195     return UNWIND_ARM64_MODE_DWARF;
1196   }
1197 #endif
1198 
1199 #if defined(_LIBUNWIND_TARGET_ARM)
1200   compact_unwind_encoding_t dwarfEncoding(Registers_arm &) const {
1201     return 0;
1202   }
1203 #endif
1204 
1205 #if defined (_LIBUNWIND_TARGET_OR1K)
1206   compact_unwind_encoding_t dwarfEncoding(Registers_or1k &) const {
1207     return 0;
1208   }
1209 #endif
1210 
1211 #if defined (_LIBUNWIND_TARGET_HEXAGON)
1212   compact_unwind_encoding_t dwarfEncoding(Registers_hexagon &) const {
1213     return 0;
1214   }
1215 #endif
1216 
1217 #if defined (_LIBUNWIND_TARGET_MIPS_O32)
1218   compact_unwind_encoding_t dwarfEncoding(Registers_mips_o32 &) const {
1219     return 0;
1220   }
1221 #endif
1222 
1223 #if defined (_LIBUNWIND_TARGET_MIPS_NEWABI)
1224   compact_unwind_encoding_t dwarfEncoding(Registers_mips_newabi &) const {
1225     return 0;
1226   }
1227 #endif
1228 
1229 #if defined(_LIBUNWIND_TARGET_SPARC)
1230   compact_unwind_encoding_t dwarfEncoding(Registers_sparc &) const { return 0; }
1231 #endif
1232 
1233 #if defined(_LIBUNWIND_TARGET_SPARC64)
1234   compact_unwind_encoding_t dwarfEncoding(Registers_sparc64 &) const {
1235     return 0;
1236   }
1237 #endif
1238 
1239 #if defined (_LIBUNWIND_TARGET_RISCV)
1240   compact_unwind_encoding_t dwarfEncoding(Registers_riscv &) const {
1241     return 0;
1242   }
1243 #endif
1244 
1245 #if defined (_LIBUNWIND_TARGET_S390X)
1246   compact_unwind_encoding_t dwarfEncoding(Registers_s390x &) const {
1247     return 0;
1248   }
1249 #endif
1250 
1251 #endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1252 
1253 #if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1254   // For runtime environments using SEH unwind data without Windows runtime
1255   // support.
1256   pint_t getLastPC() const { /* FIXME: Implement */ return 0; }
1257   void setLastPC(pint_t pc) { /* FIXME: Implement */ }
1258   RUNTIME_FUNCTION *lookUpSEHUnwindInfo(pint_t pc, pint_t *base) {
1259     /* FIXME: Implement */
1260     *base = 0;
1261     return nullptr;
1262   }
1263   bool getInfoFromSEH(pint_t pc);
1264   int stepWithSEHData() { /* FIXME: Implement */ return 0; }
1265 #endif // defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1266 
1267 #if defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
1268   bool getInfoFromTBTable(pint_t pc, R &registers);
1269   int stepWithTBTable(pint_t pc, tbtable *TBTable, R &registers,
1270                       bool &isSignalFrame);
1271   int stepWithTBTableData() {
1272     return stepWithTBTable(reinterpret_cast<pint_t>(this->getReg(UNW_REG_IP)),
1273                            reinterpret_cast<tbtable *>(_info.unwind_info),
1274                            _registers, _isSignalFrame);
1275   }
1276 #endif // defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
1277 
1278   A               &_addressSpace;
1279   R                _registers;
1280   unw_proc_info_t  _info;
1281   bool             _unwindInfoMissing;
1282   bool             _isSignalFrame;
1283 #if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN)
1284   bool             _isSigReturn = false;
1285 #endif
1286 };
1287 
1288 
1289 template <typename A, typename R>
1290 UnwindCursor<A, R>::UnwindCursor(unw_context_t *context, A &as)
1291     : _addressSpace(as), _registers(context), _unwindInfoMissing(false),
1292       _isSignalFrame(false) {
1293   static_assert((check_fit<UnwindCursor<A, R>, unw_cursor_t>::does_fit),
1294                 "UnwindCursor<> does not fit in unw_cursor_t");
1295   static_assert((alignof(UnwindCursor<A, R>) <= alignof(unw_cursor_t)),
1296                 "UnwindCursor<> requires more alignment than unw_cursor_t");
1297   memset(&_info, 0, sizeof(_info));
1298 }
1299 
1300 template <typename A, typename R>
1301 UnwindCursor<A, R>::UnwindCursor(A &as, void *)
1302     : _addressSpace(as), _unwindInfoMissing(false), _isSignalFrame(false) {
1303   memset(&_info, 0, sizeof(_info));
1304   // FIXME
1305   // fill in _registers from thread arg
1306 }
1307 
1308 
1309 template <typename A, typename R>
1310 bool UnwindCursor<A, R>::validReg(int regNum) {
1311   return _registers.validRegister(regNum);
1312 }
1313 
1314 template <typename A, typename R>
1315 unw_word_t UnwindCursor<A, R>::getReg(int regNum) {
1316   return _registers.getRegister(regNum);
1317 }
1318 
1319 template <typename A, typename R>
1320 void UnwindCursor<A, R>::setReg(int regNum, unw_word_t value) {
1321   _registers.setRegister(regNum, (typename A::pint_t)value);
1322 }
1323 
1324 template <typename A, typename R>
1325 bool UnwindCursor<A, R>::validFloatReg(int regNum) {
1326   return _registers.validFloatRegister(regNum);
1327 }
1328 
1329 template <typename A, typename R>
1330 unw_fpreg_t UnwindCursor<A, R>::getFloatReg(int regNum) {
1331   return _registers.getFloatRegister(regNum);
1332 }
1333 
1334 template <typename A, typename R>
1335 void UnwindCursor<A, R>::setFloatReg(int regNum, unw_fpreg_t value) {
1336   _registers.setFloatRegister(regNum, value);
1337 }
1338 
1339 template <typename A, typename R> void UnwindCursor<A, R>::jumpto() {
1340   _registers.jumpto();
1341 }
1342 
1343 #ifdef __arm__
1344 template <typename A, typename R> void UnwindCursor<A, R>::saveVFPAsX() {
1345   _registers.saveVFPAsX();
1346 }
1347 #endif
1348 
1349 #ifdef _AIX
1350 template <typename A, typename R>
1351 uintptr_t UnwindCursor<A, R>::getDataRelBase() {
1352   return reinterpret_cast<uintptr_t>(_info.extra);
1353 }
1354 #endif
1355 
1356 template <typename A, typename R>
1357 const char *UnwindCursor<A, R>::getRegisterName(int regNum) {
1358   return _registers.getRegisterName(regNum);
1359 }
1360 
1361 template <typename A, typename R> bool UnwindCursor<A, R>::isSignalFrame() {
1362   return _isSignalFrame;
1363 }
1364 
1365 #endif // defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1366 
1367 #if defined(_LIBUNWIND_ARM_EHABI)
1368 template<typename A>
1369 struct EHABISectionIterator {
1370   typedef EHABISectionIterator _Self;
1371 
1372   typedef typename A::pint_t value_type;
1373   typedef typename A::pint_t* pointer;
1374   typedef typename A::pint_t& reference;
1375   typedef size_t size_type;
1376   typedef size_t difference_type;
1377 
1378   static _Self begin(A& addressSpace, const UnwindInfoSections& sects) {
1379     return _Self(addressSpace, sects, 0);
1380   }
1381   static _Self end(A& addressSpace, const UnwindInfoSections& sects) {
1382     return _Self(addressSpace, sects,
1383                  sects.arm_section_length / sizeof(EHABIIndexEntry));
1384   }
1385 
1386   EHABISectionIterator(A& addressSpace, const UnwindInfoSections& sects, size_t i)
1387       : _i(i), _addressSpace(&addressSpace), _sects(&sects) {}
1388 
1389   _Self& operator++() { ++_i; return *this; }
1390   _Self& operator+=(size_t a) { _i += a; return *this; }
1391   _Self& operator--() { assert(_i > 0); --_i; return *this; }
1392   _Self& operator-=(size_t a) { assert(_i >= a); _i -= a; return *this; }
1393 
1394   _Self operator+(size_t a) { _Self out = *this; out._i += a; return out; }
1395   _Self operator-(size_t a) { assert(_i >= a); _Self out = *this; out._i -= a; return out; }
1396 
1397   size_t operator-(const _Self& other) const { return _i - other._i; }
1398 
1399   bool operator==(const _Self& other) const {
1400     assert(_addressSpace == other._addressSpace);
1401     assert(_sects == other._sects);
1402     return _i == other._i;
1403   }
1404 
1405   bool operator!=(const _Self& other) const {
1406     assert(_addressSpace == other._addressSpace);
1407     assert(_sects == other._sects);
1408     return _i != other._i;
1409   }
1410 
1411   typename A::pint_t operator*() const { return functionAddress(); }
1412 
1413   typename A::pint_t functionAddress() const {
1414     typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
1415         EHABIIndexEntry, _i, functionOffset);
1416     return indexAddr + signExtendPrel31(_addressSpace->get32(indexAddr));
1417   }
1418 
1419   typename A::pint_t dataAddress() {
1420     typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
1421         EHABIIndexEntry, _i, data);
1422     return indexAddr;
1423   }
1424 
1425  private:
1426   size_t _i;
1427   A* _addressSpace;
1428   const UnwindInfoSections* _sects;
1429 };
1430 
1431 namespace {
1432 
1433 template <typename A>
1434 EHABISectionIterator<A> EHABISectionUpperBound(
1435     EHABISectionIterator<A> first,
1436     EHABISectionIterator<A> last,
1437     typename A::pint_t value) {
1438   size_t len = last - first;
1439   while (len > 0) {
1440     size_t l2 = len / 2;
1441     EHABISectionIterator<A> m = first + l2;
1442     if (value < *m) {
1443         len = l2;
1444     } else {
1445         first = ++m;
1446         len -= l2 + 1;
1447     }
1448   }
1449   return first;
1450 }
1451 
1452 }
1453 
1454 template <typename A, typename R>
1455 bool UnwindCursor<A, R>::getInfoFromEHABISection(
1456     pint_t pc,
1457     const UnwindInfoSections &sects) {
1458   EHABISectionIterator<A> begin =
1459       EHABISectionIterator<A>::begin(_addressSpace, sects);
1460   EHABISectionIterator<A> end =
1461       EHABISectionIterator<A>::end(_addressSpace, sects);
1462   if (begin == end)
1463     return false;
1464 
1465   EHABISectionIterator<A> itNextPC = EHABISectionUpperBound(begin, end, pc);
1466   if (itNextPC == begin)
1467     return false;
1468   EHABISectionIterator<A> itThisPC = itNextPC - 1;
1469 
1470   pint_t thisPC = itThisPC.functionAddress();
1471   // If an exception is thrown from a function, corresponding to the last entry
1472   // in the table, we don't really know the function extent and have to choose a
1473   // value for nextPC. Choosing max() will allow the range check during trace to
1474   // succeed.
1475   pint_t nextPC = (itNextPC == end) ? UINTPTR_MAX : itNextPC.functionAddress();
1476   pint_t indexDataAddr = itThisPC.dataAddress();
1477 
1478   if (indexDataAddr == 0)
1479     return false;
1480 
1481   uint32_t indexData = _addressSpace.get32(indexDataAddr);
1482   if (indexData == UNW_EXIDX_CANTUNWIND)
1483     return false;
1484 
1485   // If the high bit is set, the exception handling table entry is inline inside
1486   // the index table entry on the second word (aka |indexDataAddr|). Otherwise,
1487   // the table points at an offset in the exception handling table (section 5
1488   // EHABI).
1489   pint_t exceptionTableAddr;
1490   uint32_t exceptionTableData;
1491   bool isSingleWordEHT;
1492   if (indexData & 0x80000000) {
1493     exceptionTableAddr = indexDataAddr;
1494     // TODO(ajwong): Should this data be 0?
1495     exceptionTableData = indexData;
1496     isSingleWordEHT = true;
1497   } else {
1498     exceptionTableAddr = indexDataAddr + signExtendPrel31(indexData);
1499     exceptionTableData = _addressSpace.get32(exceptionTableAddr);
1500     isSingleWordEHT = false;
1501   }
1502 
1503   // Now we know the 3 things:
1504   //   exceptionTableAddr -- exception handler table entry.
1505   //   exceptionTableData -- the data inside the first word of the eht entry.
1506   //   isSingleWordEHT -- whether the entry is in the index.
1507   unw_word_t personalityRoutine = 0xbadf00d;
1508   bool scope32 = false;
1509   uintptr_t lsda;
1510 
1511   // If the high bit in the exception handling table entry is set, the entry is
1512   // in compact form (section 6.3 EHABI).
1513   if (exceptionTableData & 0x80000000) {
1514     // Grab the index of the personality routine from the compact form.
1515     uint32_t choice = (exceptionTableData & 0x0f000000) >> 24;
1516     uint32_t extraWords = 0;
1517     switch (choice) {
1518       case 0:
1519         personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr0;
1520         extraWords = 0;
1521         scope32 = false;
1522         lsda = isSingleWordEHT ? 0 : (exceptionTableAddr + 4);
1523         break;
1524       case 1:
1525         personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr1;
1526         extraWords = (exceptionTableData & 0x00ff0000) >> 16;
1527         scope32 = false;
1528         lsda = exceptionTableAddr + (extraWords + 1) * 4;
1529         break;
1530       case 2:
1531         personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr2;
1532         extraWords = (exceptionTableData & 0x00ff0000) >> 16;
1533         scope32 = true;
1534         lsda = exceptionTableAddr + (extraWords + 1) * 4;
1535         break;
1536       default:
1537         _LIBUNWIND_ABORT("unknown personality routine");
1538         return false;
1539     }
1540 
1541     if (isSingleWordEHT) {
1542       if (extraWords != 0) {
1543         _LIBUNWIND_ABORT("index inlined table detected but pr function "
1544                          "requires extra words");
1545         return false;
1546       }
1547     }
1548   } else {
1549     pint_t personalityAddr =
1550         exceptionTableAddr + signExtendPrel31(exceptionTableData);
1551     personalityRoutine = personalityAddr;
1552 
1553     // ARM EHABI # 6.2, # 9.2
1554     //
1555     //  +---- ehtp
1556     //  v
1557     // +--------------------------------------+
1558     // | +--------+--------+--------+-------+ |
1559     // | |0| prel31 to personalityRoutine   | |
1560     // | +--------+--------+--------+-------+ |
1561     // | |      N |      unwind opcodes     | |  <-- UnwindData
1562     // | +--------+--------+--------+-------+ |
1563     // | | Word 2        unwind opcodes     | |
1564     // | +--------+--------+--------+-------+ |
1565     // | ...                                  |
1566     // | +--------+--------+--------+-------+ |
1567     // | | Word N        unwind opcodes     | |
1568     // | +--------+--------+--------+-------+ |
1569     // | | LSDA                             | |  <-- lsda
1570     // | | ...                              | |
1571     // | +--------+--------+--------+-------+ |
1572     // +--------------------------------------+
1573 
1574     uint32_t *UnwindData = reinterpret_cast<uint32_t*>(exceptionTableAddr) + 1;
1575     uint32_t FirstDataWord = *UnwindData;
1576     size_t N = ((FirstDataWord >> 24) & 0xff);
1577     size_t NDataWords = N + 1;
1578     lsda = reinterpret_cast<uintptr_t>(UnwindData + NDataWords);
1579   }
1580 
1581   _info.start_ip = thisPC;
1582   _info.end_ip = nextPC;
1583   _info.handler = personalityRoutine;
1584   _info.unwind_info = exceptionTableAddr;
1585   _info.lsda = lsda;
1586   // flags is pr_cache.additional. See EHABI #7.2 for definition of bit 0.
1587   _info.flags = (isSingleWordEHT ? 1 : 0) | (scope32 ? 0x2 : 0);  // Use enum?
1588 
1589   return true;
1590 }
1591 #endif
1592 
1593 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1594 template <typename A, typename R>
1595 bool UnwindCursor<A, R>::getInfoFromFdeCie(
1596     const typename CFI_Parser<A>::FDE_Info &fdeInfo,
1597     const typename CFI_Parser<A>::CIE_Info &cieInfo, pint_t pc,
1598     uintptr_t dso_base) {
1599   typename CFI_Parser<A>::PrologInfo prolog;
1600   if (CFI_Parser<A>::parseFDEInstructions(_addressSpace, fdeInfo, cieInfo, pc,
1601                                           R::getArch(), &prolog)) {
1602     // Save off parsed FDE info
1603     _info.start_ip          = fdeInfo.pcStart;
1604     _info.end_ip            = fdeInfo.pcEnd;
1605     _info.lsda              = fdeInfo.lsda;
1606     _info.handler           = cieInfo.personality;
1607     // Some frameless functions need SP altered when resuming in function, so
1608     // propagate spExtraArgSize.
1609     _info.gp                = prolog.spExtraArgSize;
1610     _info.flags             = 0;
1611     _info.format            = dwarfEncoding();
1612     _info.unwind_info       = fdeInfo.fdeStart;
1613     _info.unwind_info_size  = static_cast<uint32_t>(fdeInfo.fdeLength);
1614     _info.extra             = static_cast<unw_word_t>(dso_base);
1615     return true;
1616   }
1617   return false;
1618 }
1619 
1620 template <typename A, typename R>
1621 bool UnwindCursor<A, R>::getInfoFromDwarfSection(pint_t pc,
1622                                                 const UnwindInfoSections &sects,
1623                                                 uint32_t fdeSectionOffsetHint) {
1624   typename CFI_Parser<A>::FDE_Info fdeInfo;
1625   typename CFI_Parser<A>::CIE_Info cieInfo;
1626   bool foundFDE = false;
1627   bool foundInCache = false;
1628   // If compact encoding table gave offset into dwarf section, go directly there
1629   if (fdeSectionOffsetHint != 0) {
1630     foundFDE = CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
1631                                     sects.dwarf_section_length,
1632                                     sects.dwarf_section + fdeSectionOffsetHint,
1633                                     &fdeInfo, &cieInfo);
1634   }
1635 #if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
1636   if (!foundFDE && (sects.dwarf_index_section != 0)) {
1637     foundFDE = EHHeaderParser<A>::findFDE(
1638         _addressSpace, pc, sects.dwarf_index_section,
1639         (uint32_t)sects.dwarf_index_section_length, &fdeInfo, &cieInfo);
1640   }
1641 #endif
1642   if (!foundFDE) {
1643     // otherwise, search cache of previously found FDEs.
1644     pint_t cachedFDE = DwarfFDECache<A>::findFDE(sects.dso_base, pc);
1645     if (cachedFDE != 0) {
1646       foundFDE =
1647           CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
1648                                  sects.dwarf_section_length,
1649                                  cachedFDE, &fdeInfo, &cieInfo);
1650       foundInCache = foundFDE;
1651     }
1652   }
1653   if (!foundFDE) {
1654     // Still not found, do full scan of __eh_frame section.
1655     foundFDE = CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
1656                                       sects.dwarf_section_length, 0,
1657                                       &fdeInfo, &cieInfo);
1658   }
1659   if (foundFDE) {
1660     if (getInfoFromFdeCie(fdeInfo, cieInfo, pc, sects.dso_base)) {
1661       // Add to cache (to make next lookup faster) if we had no hint
1662       // and there was no index.
1663       if (!foundInCache && (fdeSectionOffsetHint == 0)) {
1664   #if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
1665         if (sects.dwarf_index_section == 0)
1666   #endif
1667         DwarfFDECache<A>::add(sects.dso_base, fdeInfo.pcStart, fdeInfo.pcEnd,
1668                               fdeInfo.fdeStart);
1669       }
1670       return true;
1671     }
1672   }
1673   //_LIBUNWIND_DEBUG_LOG("can't find/use FDE for pc=0x%llX", (uint64_t)pc);
1674   return false;
1675 }
1676 #endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
1677 
1678 
1679 #if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1680 template <typename A, typename R>
1681 bool UnwindCursor<A, R>::getInfoFromCompactEncodingSection(pint_t pc,
1682                                               const UnwindInfoSections &sects) {
1683   const bool log = false;
1684   if (log)
1685     fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX, mh=0x%llX)\n",
1686             (uint64_t)pc, (uint64_t)sects.dso_base);
1687 
1688   const UnwindSectionHeader<A> sectionHeader(_addressSpace,
1689                                                 sects.compact_unwind_section);
1690   if (sectionHeader.version() != UNWIND_SECTION_VERSION)
1691     return false;
1692 
1693   // do a binary search of top level index to find page with unwind info
1694   pint_t targetFunctionOffset = pc - sects.dso_base;
1695   const UnwindSectionIndexArray<A> topIndex(_addressSpace,
1696                                            sects.compact_unwind_section
1697                                          + sectionHeader.indexSectionOffset());
1698   uint32_t low = 0;
1699   uint32_t high = sectionHeader.indexCount();
1700   uint32_t last = high - 1;
1701   while (low < high) {
1702     uint32_t mid = (low + high) / 2;
1703     //if ( log ) fprintf(stderr, "\tmid=%d, low=%d, high=%d, *mid=0x%08X\n",
1704     //mid, low, high, topIndex.functionOffset(mid));
1705     if (topIndex.functionOffset(mid) <= targetFunctionOffset) {
1706       if ((mid == last) ||
1707           (topIndex.functionOffset(mid + 1) > targetFunctionOffset)) {
1708         low = mid;
1709         break;
1710       } else {
1711         low = mid + 1;
1712       }
1713     } else {
1714       high = mid;
1715     }
1716   }
1717   const uint32_t firstLevelFunctionOffset = topIndex.functionOffset(low);
1718   const uint32_t firstLevelNextPageFunctionOffset =
1719       topIndex.functionOffset(low + 1);
1720   const pint_t secondLevelAddr =
1721       sects.compact_unwind_section + topIndex.secondLevelPagesSectionOffset(low);
1722   const pint_t lsdaArrayStartAddr =
1723       sects.compact_unwind_section + topIndex.lsdaIndexArraySectionOffset(low);
1724   const pint_t lsdaArrayEndAddr =
1725       sects.compact_unwind_section + topIndex.lsdaIndexArraySectionOffset(low+1);
1726   if (log)
1727     fprintf(stderr, "\tfirst level search for result index=%d "
1728                     "to secondLevelAddr=0x%llX\n",
1729                     low, (uint64_t) secondLevelAddr);
1730   // do a binary search of second level page index
1731   uint32_t encoding = 0;
1732   pint_t funcStart = 0;
1733   pint_t funcEnd = 0;
1734   pint_t lsda = 0;
1735   pint_t personality = 0;
1736   uint32_t pageKind = _addressSpace.get32(secondLevelAddr);
1737   if (pageKind == UNWIND_SECOND_LEVEL_REGULAR) {
1738     // regular page
1739     UnwindSectionRegularPageHeader<A> pageHeader(_addressSpace,
1740                                                  secondLevelAddr);
1741     UnwindSectionRegularArray<A> pageIndex(
1742         _addressSpace, secondLevelAddr + pageHeader.entryPageOffset());
1743     // binary search looks for entry with e where index[e].offset <= pc <
1744     // index[e+1].offset
1745     if (log)
1746       fprintf(stderr, "\tbinary search for targetFunctionOffset=0x%08llX in "
1747                       "regular page starting at secondLevelAddr=0x%llX\n",
1748               (uint64_t) targetFunctionOffset, (uint64_t) secondLevelAddr);
1749     low = 0;
1750     high = pageHeader.entryCount();
1751     while (low < high) {
1752       uint32_t mid = (low + high) / 2;
1753       if (pageIndex.functionOffset(mid) <= targetFunctionOffset) {
1754         if (mid == (uint32_t)(pageHeader.entryCount() - 1)) {
1755           // at end of table
1756           low = mid;
1757           funcEnd = firstLevelNextPageFunctionOffset + sects.dso_base;
1758           break;
1759         } else if (pageIndex.functionOffset(mid + 1) > targetFunctionOffset) {
1760           // next is too big, so we found it
1761           low = mid;
1762           funcEnd = pageIndex.functionOffset(low + 1) + sects.dso_base;
1763           break;
1764         } else {
1765           low = mid + 1;
1766         }
1767       } else {
1768         high = mid;
1769       }
1770     }
1771     encoding = pageIndex.encoding(low);
1772     funcStart = pageIndex.functionOffset(low) + sects.dso_base;
1773     if (pc < funcStart) {
1774       if (log)
1775         fprintf(
1776             stderr,
1777             "\tpc not in table, pc=0x%llX, funcStart=0x%llX, funcEnd=0x%llX\n",
1778             (uint64_t) pc, (uint64_t) funcStart, (uint64_t) funcEnd);
1779       return false;
1780     }
1781     if (pc > funcEnd) {
1782       if (log)
1783         fprintf(
1784             stderr,
1785             "\tpc not in table, pc=0x%llX, funcStart=0x%llX, funcEnd=0x%llX\n",
1786             (uint64_t) pc, (uint64_t) funcStart, (uint64_t) funcEnd);
1787       return false;
1788     }
1789   } else if (pageKind == UNWIND_SECOND_LEVEL_COMPRESSED) {
1790     // compressed page
1791     UnwindSectionCompressedPageHeader<A> pageHeader(_addressSpace,
1792                                                     secondLevelAddr);
1793     UnwindSectionCompressedArray<A> pageIndex(
1794         _addressSpace, secondLevelAddr + pageHeader.entryPageOffset());
1795     const uint32_t targetFunctionPageOffset =
1796         (uint32_t)(targetFunctionOffset - firstLevelFunctionOffset);
1797     // binary search looks for entry with e where index[e].offset <= pc <
1798     // index[e+1].offset
1799     if (log)
1800       fprintf(stderr, "\tbinary search of compressed page starting at "
1801                       "secondLevelAddr=0x%llX\n",
1802               (uint64_t) secondLevelAddr);
1803     low = 0;
1804     last = pageHeader.entryCount() - 1;
1805     high = pageHeader.entryCount();
1806     while (low < high) {
1807       uint32_t mid = (low + high) / 2;
1808       if (pageIndex.functionOffset(mid) <= targetFunctionPageOffset) {
1809         if ((mid == last) ||
1810             (pageIndex.functionOffset(mid + 1) > targetFunctionPageOffset)) {
1811           low = mid;
1812           break;
1813         } else {
1814           low = mid + 1;
1815         }
1816       } else {
1817         high = mid;
1818       }
1819     }
1820     funcStart = pageIndex.functionOffset(low) + firstLevelFunctionOffset
1821                                                               + sects.dso_base;
1822     if (low < last)
1823       funcEnd =
1824           pageIndex.functionOffset(low + 1) + firstLevelFunctionOffset
1825                                                               + sects.dso_base;
1826     else
1827       funcEnd = firstLevelNextPageFunctionOffset + sects.dso_base;
1828     if (pc < funcStart) {
1829       _LIBUNWIND_DEBUG_LOG("malformed __unwind_info, pc=0x%llX "
1830                            "not in second level compressed unwind table. "
1831                            "funcStart=0x%llX",
1832                             (uint64_t) pc, (uint64_t) funcStart);
1833       return false;
1834     }
1835     if (pc > funcEnd) {
1836       _LIBUNWIND_DEBUG_LOG("malformed __unwind_info, pc=0x%llX "
1837                            "not in second level compressed unwind table. "
1838                            "funcEnd=0x%llX",
1839                            (uint64_t) pc, (uint64_t) funcEnd);
1840       return false;
1841     }
1842     uint16_t encodingIndex = pageIndex.encodingIndex(low);
1843     if (encodingIndex < sectionHeader.commonEncodingsArrayCount()) {
1844       // encoding is in common table in section header
1845       encoding = _addressSpace.get32(
1846           sects.compact_unwind_section +
1847           sectionHeader.commonEncodingsArraySectionOffset() +
1848           encodingIndex * sizeof(uint32_t));
1849     } else {
1850       // encoding is in page specific table
1851       uint16_t pageEncodingIndex =
1852           encodingIndex - (uint16_t)sectionHeader.commonEncodingsArrayCount();
1853       encoding = _addressSpace.get32(secondLevelAddr +
1854                                      pageHeader.encodingsPageOffset() +
1855                                      pageEncodingIndex * sizeof(uint32_t));
1856     }
1857   } else {
1858     _LIBUNWIND_DEBUG_LOG(
1859         "malformed __unwind_info at 0x%0llX bad second level page",
1860         (uint64_t)sects.compact_unwind_section);
1861     return false;
1862   }
1863 
1864   // look up LSDA, if encoding says function has one
1865   if (encoding & UNWIND_HAS_LSDA) {
1866     UnwindSectionLsdaArray<A> lsdaIndex(_addressSpace, lsdaArrayStartAddr);
1867     uint32_t funcStartOffset = (uint32_t)(funcStart - sects.dso_base);
1868     low = 0;
1869     high = (uint32_t)(lsdaArrayEndAddr - lsdaArrayStartAddr) /
1870                     sizeof(unwind_info_section_header_lsda_index_entry);
1871     // binary search looks for entry with exact match for functionOffset
1872     if (log)
1873       fprintf(stderr,
1874               "\tbinary search of lsda table for targetFunctionOffset=0x%08X\n",
1875               funcStartOffset);
1876     while (low < high) {
1877       uint32_t mid = (low + high) / 2;
1878       if (lsdaIndex.functionOffset(mid) == funcStartOffset) {
1879         lsda = lsdaIndex.lsdaOffset(mid) + sects.dso_base;
1880         break;
1881       } else if (lsdaIndex.functionOffset(mid) < funcStartOffset) {
1882         low = mid + 1;
1883       } else {
1884         high = mid;
1885       }
1886     }
1887     if (lsda == 0) {
1888       _LIBUNWIND_DEBUG_LOG("found encoding 0x%08X with HAS_LSDA bit set for "
1889                     "pc=0x%0llX, but lsda table has no entry",
1890                     encoding, (uint64_t) pc);
1891       return false;
1892     }
1893   }
1894 
1895   // extract personality routine, if encoding says function has one
1896   uint32_t personalityIndex = (encoding & UNWIND_PERSONALITY_MASK) >>
1897                               (__builtin_ctz(UNWIND_PERSONALITY_MASK));
1898   if (personalityIndex != 0) {
1899     --personalityIndex; // change 1-based to zero-based index
1900     if (personalityIndex >= sectionHeader.personalityArrayCount()) {
1901       _LIBUNWIND_DEBUG_LOG("found encoding 0x%08X with personality index %d,  "
1902                             "but personality table has only %d entries",
1903                             encoding, personalityIndex,
1904                             sectionHeader.personalityArrayCount());
1905       return false;
1906     }
1907     int32_t personalityDelta = (int32_t)_addressSpace.get32(
1908         sects.compact_unwind_section +
1909         sectionHeader.personalityArraySectionOffset() +
1910         personalityIndex * sizeof(uint32_t));
1911     pint_t personalityPointer = sects.dso_base + (pint_t)personalityDelta;
1912     personality = _addressSpace.getP(personalityPointer);
1913     if (log)
1914       fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX), "
1915                       "personalityDelta=0x%08X, personality=0x%08llX\n",
1916               (uint64_t) pc, personalityDelta, (uint64_t) personality);
1917   }
1918 
1919   if (log)
1920     fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX), "
1921                     "encoding=0x%08X, lsda=0x%08llX for funcStart=0x%llX\n",
1922             (uint64_t) pc, encoding, (uint64_t) lsda, (uint64_t) funcStart);
1923   _info.start_ip = funcStart;
1924   _info.end_ip = funcEnd;
1925   _info.lsda = lsda;
1926   _info.handler = personality;
1927   _info.gp = 0;
1928   _info.flags = 0;
1929   _info.format = encoding;
1930   _info.unwind_info = 0;
1931   _info.unwind_info_size = 0;
1932   _info.extra = sects.dso_base;
1933   return true;
1934 }
1935 #endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
1936 
1937 
1938 #if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
1939 template <typename A, typename R>
1940 bool UnwindCursor<A, R>::getInfoFromSEH(pint_t pc) {
1941   pint_t base;
1942   RUNTIME_FUNCTION *unwindEntry = lookUpSEHUnwindInfo(pc, &base);
1943   if (!unwindEntry) {
1944     _LIBUNWIND_DEBUG_LOG("\tpc not in table, pc=0x%llX", (uint64_t) pc);
1945     return false;
1946   }
1947   _info.gp = 0;
1948   _info.flags = 0;
1949   _info.format = 0;
1950   _info.unwind_info_size = sizeof(RUNTIME_FUNCTION);
1951   _info.unwind_info = reinterpret_cast<unw_word_t>(unwindEntry);
1952   _info.extra = base;
1953   _info.start_ip = base + unwindEntry->BeginAddress;
1954 #ifdef _LIBUNWIND_TARGET_X86_64
1955   _info.end_ip = base + unwindEntry->EndAddress;
1956   // Only fill in the handler and LSDA if they're stale.
1957   if (pc != getLastPC()) {
1958     UNWIND_INFO *xdata = reinterpret_cast<UNWIND_INFO *>(base + unwindEntry->UnwindData);
1959     if (xdata->Flags & (UNW_FLAG_EHANDLER|UNW_FLAG_UHANDLER)) {
1960       // The personality is given in the UNWIND_INFO itself. The LSDA immediately
1961       // follows the UNWIND_INFO. (This follows how both Clang and MSVC emit
1962       // these structures.)
1963       // N.B. UNWIND_INFO structs are DWORD-aligned.
1964       uint32_t lastcode = (xdata->CountOfCodes + 1) & ~1;
1965       const uint32_t *handler = reinterpret_cast<uint32_t *>(&xdata->UnwindCodes[lastcode]);
1966       _info.lsda = reinterpret_cast<unw_word_t>(handler+1);
1967       if (*handler) {
1968         _info.handler = reinterpret_cast<unw_word_t>(__libunwind_seh_personality);
1969       } else
1970         _info.handler = 0;
1971     } else {
1972       _info.lsda = 0;
1973       _info.handler = 0;
1974     }
1975   }
1976 #endif
1977   setLastPC(pc);
1978   return true;
1979 }
1980 #endif
1981 
1982 #if defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
1983 // Masks for traceback table field xtbtable.
1984 enum xTBTableMask : uint8_t {
1985   reservedBit = 0x02, // The traceback table was incorrectly generated if set
1986                       // (see comments in function getInfoFromTBTable().
1987   ehInfoBit = 0x08    // Exception handling info is present if set
1988 };
1989 
1990 enum frameType : unw_word_t {
1991   frameWithXLEHStateTable = 0,
1992   frameWithEHInfo = 1
1993 };
1994 
1995 extern "C" {
1996 typedef _Unwind_Reason_Code __xlcxx_personality_v0_t(int, _Unwind_Action,
1997                                                      uint64_t,
1998                                                      _Unwind_Exception *,
1999                                                      struct _Unwind_Context *);
2000 __attribute__((__weak__)) __xlcxx_personality_v0_t __xlcxx_personality_v0;
2001 }
2002 
2003 static __xlcxx_personality_v0_t *xlcPersonalityV0;
2004 static RWMutex xlcPersonalityV0InitLock;
2005 
2006 template <typename A, typename R>
2007 bool UnwindCursor<A, R>::getInfoFromTBTable(pint_t pc, R &registers) {
2008   uint32_t *p = reinterpret_cast<uint32_t *>(pc);
2009 
2010   // Keep looking forward until a word of 0 is found. The traceback
2011   // table starts at the following word.
2012   while (*p)
2013     ++p;
2014   tbtable *TBTable = reinterpret_cast<tbtable *>(p + 1);
2015 
2016   if (_LIBUNWIND_TRACING_UNWINDING) {
2017     char functionBuf[512];
2018     const char *functionName = functionBuf;
2019     unw_word_t offset;
2020     if (!getFunctionName(functionBuf, sizeof(functionBuf), &offset)) {
2021       functionName = ".anonymous.";
2022     }
2023     _LIBUNWIND_TRACE_UNWINDING("%s: Look up traceback table of func=%s at %p",
2024                                __func__, functionName,
2025                                reinterpret_cast<void *>(TBTable));
2026   }
2027 
2028   // If the traceback table does not contain necessary info, bypass this frame.
2029   if (!TBTable->tb.has_tboff)
2030     return false;
2031 
2032   // Structure tbtable_ext contains important data we are looking for.
2033   p = reinterpret_cast<uint32_t *>(&TBTable->tb_ext);
2034 
2035   // Skip field parminfo if it exists.
2036   if (TBTable->tb.fixedparms || TBTable->tb.floatparms)
2037     ++p;
2038 
2039   // p now points to tb_offset, the offset from start of function to TB table.
2040   unw_word_t start_ip =
2041       reinterpret_cast<unw_word_t>(TBTable) - *p - sizeof(uint32_t);
2042   unw_word_t end_ip = reinterpret_cast<unw_word_t>(TBTable);
2043   ++p;
2044 
2045   _LIBUNWIND_TRACE_UNWINDING("start_ip=%p, end_ip=%p\n",
2046                              reinterpret_cast<void *>(start_ip),
2047                              reinterpret_cast<void *>(end_ip));
2048 
2049   // Skip field hand_mask if it exists.
2050   if (TBTable->tb.int_hndl)
2051     ++p;
2052 
2053   unw_word_t lsda = 0;
2054   unw_word_t handler = 0;
2055   unw_word_t flags = frameType::frameWithXLEHStateTable;
2056 
2057   if (TBTable->tb.lang == TB_CPLUSPLUS && TBTable->tb.has_ctl) {
2058     // State table info is available. The ctl_info field indicates the
2059     // number of CTL anchors. There should be only one entry for the C++
2060     // state table.
2061     assert(*p == 1 && "libunwind: there must be only one ctl_info entry");
2062     ++p;
2063     // p points to the offset of the state table into the stack.
2064     pint_t stateTableOffset = *p++;
2065 
2066     int framePointerReg;
2067 
2068     // Skip fields name_len and name if exist.
2069     if (TBTable->tb.name_present) {
2070       const uint16_t name_len = *(reinterpret_cast<uint16_t *>(p));
2071       p = reinterpret_cast<uint32_t *>(reinterpret_cast<char *>(p) + name_len +
2072                                        sizeof(uint16_t));
2073     }
2074 
2075     if (TBTable->tb.uses_alloca)
2076       framePointerReg = *(reinterpret_cast<char *>(p));
2077     else
2078       framePointerReg = 1; // default frame pointer == SP
2079 
2080     _LIBUNWIND_TRACE_UNWINDING(
2081         "framePointerReg=%d, framePointer=%p, "
2082         "stateTableOffset=%#lx\n",
2083         framePointerReg,
2084         reinterpret_cast<void *>(_registers.getRegister(framePointerReg)),
2085         stateTableOffset);
2086     lsda = _registers.getRegister(framePointerReg) + stateTableOffset;
2087 
2088     // Since the traceback table generated by the legacy XLC++ does not
2089     // provide the location of the personality for the state table,
2090     // function __xlcxx_personality_v0(), which is the personality for the state
2091     // table and is exported from libc++abi, is directly assigned as the
2092     // handler here. When a legacy XLC++ frame is encountered, the symbol
2093     // is resolved dynamically using dlopen() to avoid hard dependency from
2094     // libunwind on libc++abi.
2095 
2096     // Resolve the function pointer to the state table personality if it has
2097     // not already.
2098     if (xlcPersonalityV0 == NULL) {
2099       xlcPersonalityV0InitLock.lock();
2100       if (xlcPersonalityV0 == NULL) {
2101         // If libc++abi is statically linked in, symbol __xlcxx_personality_v0
2102         // has been resolved at the link time.
2103         xlcPersonalityV0 = &__xlcxx_personality_v0;
2104         if (xlcPersonalityV0 == NULL) {
2105           // libc++abi is dynamically linked. Resolve __xlcxx_personality_v0
2106           // using dlopen().
2107           const char libcxxabi[] = "libc++abi.a(libc++abi.so.1)";
2108           void *libHandle;
2109           libHandle = dlopen(libcxxabi, RTLD_MEMBER | RTLD_NOW);
2110           if (libHandle == NULL) {
2111             _LIBUNWIND_TRACE_UNWINDING("dlopen() failed with errno=%d\n",
2112                                        errno);
2113             assert(0 && "dlopen() failed");
2114           }
2115           xlcPersonalityV0 = reinterpret_cast<__xlcxx_personality_v0_t *>(
2116               dlsym(libHandle, "__xlcxx_personality_v0"));
2117           if (xlcPersonalityV0 == NULL) {
2118             _LIBUNWIND_TRACE_UNWINDING("dlsym() failed with errno=%d\n", errno);
2119             assert(0 && "dlsym() failed");
2120           }
2121           dlclose(libHandle);
2122         }
2123       }
2124       xlcPersonalityV0InitLock.unlock();
2125     }
2126     handler = reinterpret_cast<unw_word_t>(xlcPersonalityV0);
2127     _LIBUNWIND_TRACE_UNWINDING("State table: LSDA=%p, Personality=%p\n",
2128                                reinterpret_cast<void *>(lsda),
2129                                reinterpret_cast<void *>(handler));
2130   } else if (TBTable->tb.longtbtable) {
2131     // This frame has the traceback table extension. Possible cases are
2132     // 1) a C++ frame that has the 'eh_info' structure; 2) a C++ frame that
2133     // is not EH aware; or, 3) a frame of other languages. We need to figure out
2134     // if the traceback table extension contains the 'eh_info' structure.
2135     //
2136     // We also need to deal with the complexity arising from some XL compiler
2137     // versions use the wrong ordering of 'longtbtable' and 'has_vec' bits
2138     // where the 'longtbtable' bit is meant to be the 'has_vec' bit and vice
2139     // versa. For frames of code generated by those compilers, the 'longtbtable'
2140     // bit may be set but there isn't really a traceback table extension.
2141     //
2142     // In </usr/include/sys/debug.h>, there is the following definition of
2143     // 'struct tbtable_ext'. It is not really a structure but a dummy to
2144     // collect the description of optional parts of the traceback table.
2145     //
2146     // struct tbtable_ext {
2147     //   ...
2148     //   char alloca_reg;        /* Register for alloca automatic storage */
2149     //   struct vec_ext vec_ext; /* Vector extension (if has_vec is set) */
2150     //   unsigned char xtbtable; /* More tbtable fields, if longtbtable is set*/
2151     // };
2152     //
2153     // Depending on how the 'has_vec'/'longtbtable' bit is interpreted, the data
2154     // following 'alloca_reg' can be treated either as 'struct vec_ext' or
2155     // 'unsigned char xtbtable'. 'xtbtable' bits are defined in
2156     // </usr/include/sys/debug.h> as flags. The 7th bit '0x02' is currently
2157     // unused and should not be set. 'struct vec_ext' is defined in
2158     // </usr/include/sys/debug.h> as follows:
2159     //
2160     // struct vec_ext {
2161     //   unsigned vr_saved:6;      /* Number of non-volatile vector regs saved
2162     //   */
2163     //                             /* first register saved is assumed to be */
2164     //                             /* 32 - vr_saved                         */
2165     //   unsigned saves_vrsave:1;  /* Set if vrsave is saved on the stack */
2166     //   unsigned has_varargs:1;
2167     //   ...
2168     // };
2169     //
2170     // Here, the 7th bit is used as 'saves_vrsave'. To determine whether it
2171     // is 'struct vec_ext' or 'xtbtable' that follows 'alloca_reg',
2172     // we checks if the 7th bit is set or not because 'xtbtable' should
2173     // never have the 7th bit set. The 7th bit of 'xtbtable' will be reserved
2174     // in the future to make sure the mitigation works. This mitigation
2175     // is not 100% bullet proof because 'struct vec_ext' may not always have
2176     // 'saves_vrsave' bit set.
2177     //
2178     // 'reservedBit' is defined in enum 'xTBTableMask' above as the mask for
2179     // checking the 7th bit.
2180 
2181     // p points to field name len.
2182     uint8_t *charPtr = reinterpret_cast<uint8_t *>(p);
2183 
2184     // Skip fields name_len and name if they exist.
2185     if (TBTable->tb.name_present) {
2186       const uint16_t name_len = *(reinterpret_cast<uint16_t *>(charPtr));
2187       charPtr = charPtr + name_len + sizeof(uint16_t);
2188     }
2189 
2190     // Skip field alloc_reg if it exists.
2191     if (TBTable->tb.uses_alloca)
2192       ++charPtr;
2193 
2194     // Check traceback table bit has_vec. Skip struct vec_ext if it exists.
2195     if (TBTable->tb.has_vec)
2196       // Note struct vec_ext does exist at this point because whether the
2197       // ordering of longtbtable and has_vec bits is correct or not, both
2198       // are set.
2199       charPtr += sizeof(struct vec_ext);
2200 
2201     // charPtr points to field 'xtbtable'. Check if the EH info is available.
2202     // Also check if the reserved bit of the extended traceback table field
2203     // 'xtbtable' is set. If it is, the traceback table was incorrectly
2204     // generated by an XL compiler that uses the wrong ordering of 'longtbtable'
2205     // and 'has_vec' bits and this is in fact 'struct vec_ext'. So skip the
2206     // frame.
2207     if ((*charPtr & xTBTableMask::ehInfoBit) &&
2208         !(*charPtr & xTBTableMask::reservedBit)) {
2209       // Mark this frame has the new EH info.
2210       flags = frameType::frameWithEHInfo;
2211 
2212       // eh_info is available.
2213       charPtr++;
2214       // The pointer is 4-byte aligned.
2215       if (reinterpret_cast<uintptr_t>(charPtr) % 4)
2216         charPtr += 4 - reinterpret_cast<uintptr_t>(charPtr) % 4;
2217       uintptr_t *ehInfo =
2218           reinterpret_cast<uintptr_t *>(*(reinterpret_cast<uintptr_t *>(
2219               registers.getRegister(2) +
2220               *(reinterpret_cast<uintptr_t *>(charPtr)))));
2221 
2222       // ehInfo points to structure en_info. The first member is version.
2223       // Only version 0 is currently supported.
2224       assert(*(reinterpret_cast<uint32_t *>(ehInfo)) == 0 &&
2225              "libunwind: ehInfo version other than 0 is not supported");
2226 
2227       // Increment ehInfo to point to member lsda.
2228       ++ehInfo;
2229       lsda = *ehInfo++;
2230 
2231       // enInfo now points to member personality.
2232       handler = *ehInfo;
2233 
2234       _LIBUNWIND_TRACE_UNWINDING("Range table: LSDA=%#lx, Personality=%#lx\n",
2235                                  lsda, handler);
2236     }
2237   }
2238 
2239   _info.start_ip = start_ip;
2240   _info.end_ip = end_ip;
2241   _info.lsda = lsda;
2242   _info.handler = handler;
2243   _info.gp = 0;
2244   _info.flags = flags;
2245   _info.format = 0;
2246   _info.unwind_info = reinterpret_cast<unw_word_t>(TBTable);
2247   _info.unwind_info_size = 0;
2248   _info.extra = registers.getRegister(2);
2249 
2250   return true;
2251 }
2252 
2253 // Step back up the stack following the frame back link.
2254 template <typename A, typename R>
2255 int UnwindCursor<A, R>::stepWithTBTable(pint_t pc, tbtable *TBTable,
2256                                         R &registers, bool &isSignalFrame) {
2257   if (_LIBUNWIND_TRACING_UNWINDING) {
2258     char functionBuf[512];
2259     const char *functionName = functionBuf;
2260     unw_word_t offset;
2261     if (!getFunctionName(functionBuf, sizeof(functionBuf), &offset)) {
2262       functionName = ".anonymous.";
2263     }
2264     _LIBUNWIND_TRACE_UNWINDING("%s: Look up traceback table of func=%s at %p",
2265                                __func__, functionName,
2266                                reinterpret_cast<void *>(TBTable));
2267   }
2268 
2269 #if defined(__powerpc64__)
2270   // Instruction to reload TOC register "l r2,40(r1)"
2271   const uint32_t loadTOCRegInst = 0xe8410028;
2272   const int32_t unwPPCF0Index = UNW_PPC64_F0;
2273   const int32_t unwPPCV0Index = UNW_PPC64_V0;
2274 #else
2275   // Instruction to reload TOC register "l r2,20(r1)"
2276   const uint32_t loadTOCRegInst = 0x80410014;
2277   const int32_t unwPPCF0Index = UNW_PPC_F0;
2278   const int32_t unwPPCV0Index = UNW_PPC_V0;
2279 #endif
2280 
2281   R newRegisters = registers;
2282 
2283   // lastStack points to the stack frame of the next routine up.
2284   pint_t lastStack = *(reinterpret_cast<pint_t *>(registers.getSP()));
2285 
2286   // Return address is the address after call site instruction.
2287   pint_t returnAddress;
2288 
2289   if (isSignalFrame) {
2290     _LIBUNWIND_TRACE_UNWINDING("Possible signal handler frame: lastStack=%p",
2291                                reinterpret_cast<void *>(lastStack));
2292 
2293     sigcontext *sigContext = reinterpret_cast<sigcontext *>(
2294         reinterpret_cast<char *>(lastStack) + STKMIN);
2295     returnAddress = sigContext->sc_jmpbuf.jmp_context.iar;
2296 
2297     _LIBUNWIND_TRACE_UNWINDING("From sigContext=%p, returnAddress=%p\n",
2298                                reinterpret_cast<void *>(sigContext),
2299                                reinterpret_cast<void *>(returnAddress));
2300 
2301     if (returnAddress < 0x10000000) {
2302       // Try again using STKMINALIGN
2303       sigContext = reinterpret_cast<sigcontext *>(
2304           reinterpret_cast<char *>(lastStack) + STKMINALIGN);
2305       returnAddress = sigContext->sc_jmpbuf.jmp_context.iar;
2306       if (returnAddress < 0x10000000) {
2307         _LIBUNWIND_TRACE_UNWINDING("Bad returnAddress=%p\n",
2308                                    reinterpret_cast<void *>(returnAddress));
2309         return UNW_EBADFRAME;
2310       } else {
2311         _LIBUNWIND_TRACE_UNWINDING("Tried again using STKMINALIGN: "
2312                                    "sigContext=%p, returnAddress=%p. "
2313                                    "Seems to be a valid address\n",
2314                                    reinterpret_cast<void *>(sigContext),
2315                                    reinterpret_cast<void *>(returnAddress));
2316       }
2317     }
2318     // Restore the condition register from sigcontext.
2319     newRegisters.setCR(sigContext->sc_jmpbuf.jmp_context.cr);
2320 
2321     // Restore GPRs from sigcontext.
2322     for (int i = 0; i < 32; ++i)
2323       newRegisters.setRegister(i, sigContext->sc_jmpbuf.jmp_context.gpr[i]);
2324 
2325     // Restore FPRs from sigcontext.
2326     for (int i = 0; i < 32; ++i)
2327       newRegisters.setFloatRegister(i + unwPPCF0Index,
2328                                     sigContext->sc_jmpbuf.jmp_context.fpr[i]);
2329 
2330     // Restore vector registers if there is an associated extended context
2331     // structure.
2332     if (sigContext->sc_jmpbuf.jmp_context.msr & __EXTCTX) {
2333       ucontext_t *uContext = reinterpret_cast<ucontext_t *>(sigContext);
2334       if (uContext->__extctx->__extctx_magic == __EXTCTX_MAGIC) {
2335         for (int i = 0; i < 32; ++i)
2336           newRegisters.setVectorRegister(
2337               i + unwPPCV0Index, *(reinterpret_cast<v128 *>(
2338                                      &(uContext->__extctx->__vmx.__vr[i]))));
2339       }
2340     }
2341   } else {
2342     // Step up a normal frame.
2343     returnAddress = reinterpret_cast<pint_t *>(lastStack)[2];
2344 
2345     _LIBUNWIND_TRACE_UNWINDING("Extract info from lastStack=%p, "
2346                                "returnAddress=%p\n",
2347                                reinterpret_cast<void *>(lastStack),
2348                                reinterpret_cast<void *>(returnAddress));
2349     _LIBUNWIND_TRACE_UNWINDING("fpr_regs=%d, gpr_regs=%d, saves_cr=%d\n",
2350                                TBTable->tb.fpr_saved, TBTable->tb.gpr_saved,
2351                                TBTable->tb.saves_cr);
2352 
2353     // Restore FP registers.
2354     char *ptrToRegs = reinterpret_cast<char *>(lastStack);
2355     double *FPRegs = reinterpret_cast<double *>(
2356         ptrToRegs - (TBTable->tb.fpr_saved * sizeof(double)));
2357     for (int i = 0; i < TBTable->tb.fpr_saved; ++i)
2358       newRegisters.setFloatRegister(
2359           32 - TBTable->tb.fpr_saved + i + unwPPCF0Index, FPRegs[i]);
2360 
2361     // Restore GP registers.
2362     ptrToRegs = reinterpret_cast<char *>(FPRegs);
2363     uintptr_t *GPRegs = reinterpret_cast<uintptr_t *>(
2364         ptrToRegs - (TBTable->tb.gpr_saved * sizeof(uintptr_t)));
2365     for (int i = 0; i < TBTable->tb.gpr_saved; ++i)
2366       newRegisters.setRegister(32 - TBTable->tb.gpr_saved + i, GPRegs[i]);
2367 
2368     // Restore Vector registers.
2369     ptrToRegs = reinterpret_cast<char *>(GPRegs);
2370 
2371     // Restore vector registers only if this is a Clang frame. Also
2372     // check if traceback table bit has_vec is set. If it is, structure
2373     // vec_ext is available.
2374     if (_info.flags == frameType::frameWithEHInfo && TBTable->tb.has_vec) {
2375 
2376       // Get to the vec_ext structure to check if vector registers are saved.
2377       uint32_t *p = reinterpret_cast<uint32_t *>(&TBTable->tb_ext);
2378 
2379       // Skip field parminfo if exists.
2380       if (TBTable->tb.fixedparms || TBTable->tb.floatparms)
2381         ++p;
2382 
2383       // Skip field tb_offset if exists.
2384       if (TBTable->tb.has_tboff)
2385         ++p;
2386 
2387       // Skip field hand_mask if exists.
2388       if (TBTable->tb.int_hndl)
2389         ++p;
2390 
2391       // Skip fields ctl_info and ctl_info_disp if exist.
2392       if (TBTable->tb.has_ctl) {
2393         // Skip field ctl_info.
2394         ++p;
2395         // Skip field ctl_info_disp.
2396         ++p;
2397       }
2398 
2399       // Skip fields name_len and name if exist.
2400       // p is supposed to point to field name_len now.
2401       uint8_t *charPtr = reinterpret_cast<uint8_t *>(p);
2402       if (TBTable->tb.name_present) {
2403         const uint16_t name_len = *(reinterpret_cast<uint16_t *>(charPtr));
2404         charPtr = charPtr + name_len + sizeof(uint16_t);
2405       }
2406 
2407       // Skip field alloc_reg if it exists.
2408       if (TBTable->tb.uses_alloca)
2409         ++charPtr;
2410 
2411       struct vec_ext *vec_ext = reinterpret_cast<struct vec_ext *>(charPtr);
2412 
2413       _LIBUNWIND_TRACE_UNWINDING("vr_saved=%d\n", vec_ext->vr_saved);
2414 
2415       // Restore vector register(s) if saved on the stack.
2416       if (vec_ext->vr_saved) {
2417         // Saved vector registers are 16-byte aligned.
2418         if (reinterpret_cast<uintptr_t>(ptrToRegs) % 16)
2419           ptrToRegs -= reinterpret_cast<uintptr_t>(ptrToRegs) % 16;
2420         v128 *VecRegs = reinterpret_cast<v128 *>(ptrToRegs - vec_ext->vr_saved *
2421                                                                  sizeof(v128));
2422         for (int i = 0; i < vec_ext->vr_saved; ++i) {
2423           newRegisters.setVectorRegister(
2424               32 - vec_ext->vr_saved + i + unwPPCV0Index, VecRegs[i]);
2425         }
2426       }
2427     }
2428     if (TBTable->tb.saves_cr) {
2429       // Get the saved condition register. The condition register is only
2430       // a single word.
2431       newRegisters.setCR(
2432           *(reinterpret_cast<uint32_t *>(lastStack + sizeof(uintptr_t))));
2433     }
2434 
2435     // Restore the SP.
2436     newRegisters.setSP(lastStack);
2437 
2438     // The first instruction after return.
2439     uint32_t firstInstruction = *(reinterpret_cast<uint32_t *>(returnAddress));
2440 
2441     // Do we need to set the TOC register?
2442     _LIBUNWIND_TRACE_UNWINDING(
2443         "Current gpr2=%p\n",
2444         reinterpret_cast<void *>(newRegisters.getRegister(2)));
2445     if (firstInstruction == loadTOCRegInst) {
2446       _LIBUNWIND_TRACE_UNWINDING(
2447           "Set gpr2=%p from frame\n",
2448           reinterpret_cast<void *>(reinterpret_cast<pint_t *>(lastStack)[5]));
2449       newRegisters.setRegister(2, reinterpret_cast<pint_t *>(lastStack)[5]);
2450     }
2451   }
2452   _LIBUNWIND_TRACE_UNWINDING("lastStack=%p, returnAddress=%p, pc=%p\n",
2453                              reinterpret_cast<void *>(lastStack),
2454                              reinterpret_cast<void *>(returnAddress),
2455                              reinterpret_cast<void *>(pc));
2456 
2457   // The return address is the address after call site instruction, so
2458   // setting IP to that simualates a return.
2459   newRegisters.setIP(reinterpret_cast<uintptr_t>(returnAddress));
2460 
2461   // Simulate the step by replacing the register set with the new ones.
2462   registers = newRegisters;
2463 
2464   // Check if the next frame is a signal frame.
2465   pint_t nextStack = *(reinterpret_cast<pint_t *>(registers.getSP()));
2466 
2467   // Return address is the address after call site instruction.
2468   pint_t nextReturnAddress = reinterpret_cast<pint_t *>(nextStack)[2];
2469 
2470   if (nextReturnAddress > 0x01 && nextReturnAddress < 0x10000) {
2471     _LIBUNWIND_TRACE_UNWINDING("The next is a signal handler frame: "
2472                                "nextStack=%p, next return address=%p\n",
2473                                reinterpret_cast<void *>(nextStack),
2474                                reinterpret_cast<void *>(nextReturnAddress));
2475     isSignalFrame = true;
2476   } else {
2477     isSignalFrame = false;
2478   }
2479 
2480   return UNW_STEP_SUCCESS;
2481 }
2482 #endif // defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
2483 
2484 template <typename A, typename R>
2485 void UnwindCursor<A, R>::setInfoBasedOnIPRegister(bool isReturnAddress) {
2486 #if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN)
2487   _isSigReturn = false;
2488 #endif
2489 
2490   pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
2491 #if defined(_LIBUNWIND_ARM_EHABI)
2492   // Remove the thumb bit so the IP represents the actual instruction address.
2493   // This matches the behaviour of _Unwind_GetIP on arm.
2494   pc &= (pint_t)~0x1;
2495 #endif
2496 
2497   // Exit early if at the top of the stack.
2498   if (pc == 0) {
2499     _unwindInfoMissing = true;
2500     return;
2501   }
2502 
2503   // If the last line of a function is a "throw" the compiler sometimes
2504   // emits no instructions after the call to __cxa_throw.  This means
2505   // the return address is actually the start of the next function.
2506   // To disambiguate this, back up the pc when we know it is a return
2507   // address.
2508   if (isReturnAddress)
2509 #if defined(_AIX)
2510     // PC needs to be a 4-byte aligned address to be able to look for a
2511     // word of 0 that indicates the start of the traceback table at the end
2512     // of a function on AIX.
2513     pc -= 4;
2514 #else
2515     --pc;
2516 #endif
2517 
2518   // Ask address space object to find unwind sections for this pc.
2519   UnwindInfoSections sects;
2520   if (_addressSpace.findUnwindSections(pc, sects)) {
2521 #if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
2522     // If there is a compact unwind encoding table, look there first.
2523     if (sects.compact_unwind_section != 0) {
2524       if (this->getInfoFromCompactEncodingSection(pc, sects)) {
2525   #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
2526         // Found info in table, done unless encoding says to use dwarf.
2527         uint32_t dwarfOffset;
2528         if ((sects.dwarf_section != 0) && compactSaysUseDwarf(&dwarfOffset)) {
2529           if (this->getInfoFromDwarfSection(pc, sects, dwarfOffset)) {
2530             // found info in dwarf, done
2531             return;
2532           }
2533         }
2534   #endif
2535         // If unwind table has entry, but entry says there is no unwind info,
2536         // record that we have no unwind info.
2537         if (_info.format == 0)
2538           _unwindInfoMissing = true;
2539         return;
2540       }
2541     }
2542 #endif // defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
2543 
2544 #if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
2545     // If there is SEH unwind info, look there next.
2546     if (this->getInfoFromSEH(pc))
2547       return;
2548 #endif
2549 
2550 #if defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
2551     // If there is unwind info in the traceback table, look there next.
2552     if (this->getInfoFromTBTable(pc, _registers))
2553       return;
2554 #endif
2555 
2556 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
2557     // If there is dwarf unwind info, look there next.
2558     if (sects.dwarf_section != 0) {
2559       if (this->getInfoFromDwarfSection(pc, sects)) {
2560         // found info in dwarf, done
2561         return;
2562       }
2563     }
2564 #endif
2565 
2566 #if defined(_LIBUNWIND_ARM_EHABI)
2567     // If there is ARM EHABI unwind info, look there next.
2568     if (sects.arm_section != 0 && this->getInfoFromEHABISection(pc, sects))
2569       return;
2570 #endif
2571   }
2572 
2573 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
2574   // There is no static unwind info for this pc. Look to see if an FDE was
2575   // dynamically registered for it.
2576   pint_t cachedFDE = DwarfFDECache<A>::findFDE(DwarfFDECache<A>::kSearchAll,
2577                                                pc);
2578   if (cachedFDE != 0) {
2579     typename CFI_Parser<A>::FDE_Info fdeInfo;
2580     typename CFI_Parser<A>::CIE_Info cieInfo;
2581     if (!CFI_Parser<A>::decodeFDE(_addressSpace, cachedFDE, &fdeInfo, &cieInfo))
2582       if (getInfoFromFdeCie(fdeInfo, cieInfo, pc, 0))
2583         return;
2584   }
2585 
2586   // Lastly, ask AddressSpace object about platform specific ways to locate
2587   // other FDEs.
2588   pint_t fde;
2589   if (_addressSpace.findOtherFDE(pc, fde)) {
2590     typename CFI_Parser<A>::FDE_Info fdeInfo;
2591     typename CFI_Parser<A>::CIE_Info cieInfo;
2592     if (!CFI_Parser<A>::decodeFDE(_addressSpace, fde, &fdeInfo, &cieInfo)) {
2593       // Double check this FDE is for a function that includes the pc.
2594       if ((fdeInfo.pcStart <= pc) && (pc < fdeInfo.pcEnd))
2595         if (getInfoFromFdeCie(fdeInfo, cieInfo, pc, 0))
2596           return;
2597     }
2598   }
2599 #endif // #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
2600 
2601 #if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN)
2602   if (setInfoForSigReturn())
2603     return;
2604 #endif
2605 
2606   // no unwind info, flag that we can't reliably unwind
2607   _unwindInfoMissing = true;
2608 }
2609 
2610 #if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&                               \
2611     defined(_LIBUNWIND_TARGET_AARCH64)
2612 template <typename A, typename R>
2613 bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_arm64 &) {
2614   // Look for the sigreturn trampoline. The trampoline's body is two
2615   // specific instructions (see below). Typically the trampoline comes from the
2616   // vDSO[1] (i.e. the __kernel_rt_sigreturn function). A libc might provide its
2617   // own restorer function, though, or user-mode QEMU might write a trampoline
2618   // onto the stack.
2619   //
2620   // This special code path is a fallback that is only used if the trampoline
2621   // lacks proper (e.g. DWARF) unwind info. On AArch64, a new DWARF register
2622   // constant for the PC needs to be defined before DWARF can handle a signal
2623   // trampoline. This code may segfault if the target PC is unreadable, e.g.:
2624   //  - The PC points at a function compiled without unwind info, and which is
2625   //    part of an execute-only mapping (e.g. using -Wl,--execute-only).
2626   //  - The PC is invalid and happens to point to unreadable or unmapped memory.
2627   //
2628   // [1] https://github.com/torvalds/linux/blob/master/arch/arm64/kernel/vdso/sigreturn.S
2629   const pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
2630   // The PC might contain an invalid address if the unwind info is bad, so
2631   // directly accessing it could cause a segfault. Use process_vm_readv to read
2632   // the memory safely instead. process_vm_readv was added in Linux 3.2, and
2633   // AArch64 supported was added in Linux 3.7, so the syscall is guaranteed to
2634   // be present. Unfortunately, there are Linux AArch64 environments where the
2635   // libc wrapper for the syscall might not be present (e.g. Android 5), so call
2636   // the syscall directly instead.
2637   uint32_t instructions[2];
2638   struct iovec local_iov = {&instructions, sizeof instructions};
2639   struct iovec remote_iov = {reinterpret_cast<void *>(pc), sizeof instructions};
2640   long bytesRead =
2641       syscall(SYS_process_vm_readv, getpid(), &local_iov, 1, &remote_iov, 1, 0);
2642   // Look for instructions: mov x8, #0x8b; svc #0x0
2643   if (bytesRead != sizeof instructions || instructions[0] != 0xd2801168 ||
2644       instructions[1] != 0xd4000001)
2645     return false;
2646 
2647   _info = {};
2648   _info.start_ip = pc;
2649   _info.end_ip = pc + 4;
2650   _isSigReturn = true;
2651   return true;
2652 }
2653 
2654 template <typename A, typename R>
2655 int UnwindCursor<A, R>::stepThroughSigReturn(Registers_arm64 &) {
2656   // In the signal trampoline frame, sp points to an rt_sigframe[1], which is:
2657   //  - 128-byte siginfo struct
2658   //  - ucontext struct:
2659   //     - 8-byte long (uc_flags)
2660   //     - 8-byte pointer (uc_link)
2661   //     - 24-byte stack_t
2662   //     - 128-byte signal set
2663   //     - 8 bytes of padding because sigcontext has 16-byte alignment
2664   //     - sigcontext/mcontext_t
2665   // [1] https://github.com/torvalds/linux/blob/master/arch/arm64/kernel/signal.c
2666   const pint_t kOffsetSpToSigcontext = (128 + 8 + 8 + 24 + 128 + 8); // 304
2667 
2668   // Offsets from sigcontext to each register.
2669   const pint_t kOffsetGprs = 8; // offset to "__u64 regs[31]" field
2670   const pint_t kOffsetSp = 256; // offset to "__u64 sp" field
2671   const pint_t kOffsetPc = 264; // offset to "__u64 pc" field
2672 
2673   pint_t sigctx = _registers.getSP() + kOffsetSpToSigcontext;
2674 
2675   for (int i = 0; i <= 30; ++i) {
2676     uint64_t value = _addressSpace.get64(sigctx + kOffsetGprs +
2677                                          static_cast<pint_t>(i * 8));
2678     _registers.setRegister(UNW_AARCH64_X0 + i, value);
2679   }
2680   _registers.setSP(_addressSpace.get64(sigctx + kOffsetSp));
2681   _registers.setIP(_addressSpace.get64(sigctx + kOffsetPc));
2682   _isSignalFrame = true;
2683   return UNW_STEP_SUCCESS;
2684 }
2685 #endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&
2686        // defined(_LIBUNWIND_TARGET_AARCH64)
2687 
2688 #if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&                               \
2689     defined(_LIBUNWIND_TARGET_S390X)
2690 template <typename A, typename R>
2691 bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_s390x &) {
2692   // Look for the sigreturn trampoline. The trampoline's body is a
2693   // specific instruction (see below). Typically the trampoline comes from the
2694   // vDSO (i.e. the __kernel_[rt_]sigreturn function). A libc might provide its
2695   // own restorer function, though, or user-mode QEMU might write a trampoline
2696   // onto the stack.
2697   const pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
2698   // The PC might contain an invalid address if the unwind info is bad, so
2699   // directly accessing it could cause a segfault. Use process_vm_readv to
2700   // read the memory safely instead.
2701   uint16_t inst;
2702   struct iovec local_iov = {&inst, sizeof inst};
2703   struct iovec remote_iov = {reinterpret_cast<void *>(pc), sizeof inst};
2704   long bytesRead = process_vm_readv(getpid(), &local_iov, 1, &remote_iov, 1, 0);
2705   if (bytesRead == sizeof inst && (inst == 0x0a77 || inst == 0x0aad)) {
2706     _info = {};
2707     _info.start_ip = pc;
2708     _info.end_ip = pc + 2;
2709     _isSigReturn = true;
2710     return true;
2711   }
2712   return false;
2713 }
2714 
2715 template <typename A, typename R>
2716 int UnwindCursor<A, R>::stepThroughSigReturn(Registers_s390x &) {
2717   // Determine current SP.
2718   const pint_t sp = static_cast<pint_t>(this->getReg(UNW_REG_SP));
2719   // According to the s390x ABI, the CFA is at (incoming) SP + 160.
2720   const pint_t cfa = sp + 160;
2721 
2722   // Determine current PC and instruction there (this must be either
2723   // a "svc __NR_sigreturn" or "svc __NR_rt_sigreturn").
2724   const pint_t pc = static_cast<pint_t>(this->getReg(UNW_REG_IP));
2725   const uint16_t inst = _addressSpace.get16(pc);
2726 
2727   // Find the addresses of the signo and sigcontext in the frame.
2728   pint_t pSigctx = 0;
2729   pint_t pSigno = 0;
2730 
2731   // "svc __NR_sigreturn" uses a non-RT signal trampoline frame.
2732   if (inst == 0x0a77) {
2733     // Layout of a non-RT signal trampoline frame, starting at the CFA:
2734     //  - 8-byte signal mask
2735     //  - 8-byte pointer to sigcontext, followed by signo
2736     //  - 4-byte signo
2737     pSigctx = _addressSpace.get64(cfa + 8);
2738     pSigno = pSigctx + 344;
2739   }
2740 
2741   // "svc __NR_rt_sigreturn" uses a RT signal trampoline frame.
2742   if (inst == 0x0aad) {
2743     // Layout of a RT signal trampoline frame, starting at the CFA:
2744     //  - 8-byte retcode (+ alignment)
2745     //  - 128-byte siginfo struct (starts with signo)
2746     //  - ucontext struct:
2747     //     - 8-byte long (uc_flags)
2748     //     - 8-byte pointer (uc_link)
2749     //     - 24-byte stack_t
2750     //     - 8 bytes of padding because sigcontext has 16-byte alignment
2751     //     - sigcontext/mcontext_t
2752     pSigctx = cfa + 8 + 128 + 8 + 8 + 24 + 8;
2753     pSigno = cfa + 8;
2754   }
2755 
2756   assert(pSigctx != 0);
2757   assert(pSigno != 0);
2758 
2759   // Offsets from sigcontext to each register.
2760   const pint_t kOffsetPc = 8;
2761   const pint_t kOffsetGprs = 16;
2762   const pint_t kOffsetFprs = 216;
2763 
2764   // Restore all registers.
2765   for (int i = 0; i < 16; ++i) {
2766     uint64_t value = _addressSpace.get64(pSigctx + kOffsetGprs +
2767                                          static_cast<pint_t>(i * 8));
2768     _registers.setRegister(UNW_S390X_R0 + i, value);
2769   }
2770   for (int i = 0; i < 16; ++i) {
2771     static const int fpr[16] = {
2772       UNW_S390X_F0, UNW_S390X_F1, UNW_S390X_F2, UNW_S390X_F3,
2773       UNW_S390X_F4, UNW_S390X_F5, UNW_S390X_F6, UNW_S390X_F7,
2774       UNW_S390X_F8, UNW_S390X_F9, UNW_S390X_F10, UNW_S390X_F11,
2775       UNW_S390X_F12, UNW_S390X_F13, UNW_S390X_F14, UNW_S390X_F15
2776     };
2777     double value = _addressSpace.getDouble(pSigctx + kOffsetFprs +
2778                                            static_cast<pint_t>(i * 8));
2779     _registers.setFloatRegister(fpr[i], value);
2780   }
2781   _registers.setIP(_addressSpace.get64(pSigctx + kOffsetPc));
2782 
2783   // SIGILL, SIGFPE and SIGTRAP are delivered with psw_addr
2784   // after the faulting instruction rather than before it.
2785   // Do not set _isSignalFrame in that case.
2786   uint32_t signo = _addressSpace.get32(pSigno);
2787   _isSignalFrame = (signo != 4 && signo != 5 && signo != 8);
2788 
2789   return UNW_STEP_SUCCESS;
2790 }
2791 #endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) &&
2792        // defined(_LIBUNWIND_TARGET_S390X)
2793 
2794 template <typename A, typename R>
2795 int UnwindCursor<A, R>::step() {
2796   // Bottom of stack is defined is when unwind info cannot be found.
2797   if (_unwindInfoMissing)
2798     return UNW_STEP_END;
2799 
2800   // Use unwinding info to modify register set as if function returned.
2801   int result;
2802 #if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN)
2803   if (_isSigReturn) {
2804     result = this->stepThroughSigReturn();
2805   } else
2806 #endif
2807   {
2808 #if defined(_LIBUNWIND_SUPPORT_COMPACT_UNWIND)
2809     result = this->stepWithCompactEncoding();
2810 #elif defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
2811     result = this->stepWithSEHData();
2812 #elif defined(_LIBUNWIND_SUPPORT_TBTAB_UNWIND)
2813     result = this->stepWithTBTableData();
2814 #elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
2815     result = this->stepWithDwarfFDE();
2816 #elif defined(_LIBUNWIND_ARM_EHABI)
2817     result = this->stepWithEHABI();
2818 #else
2819   #error Need _LIBUNWIND_SUPPORT_COMPACT_UNWIND or \
2820               _LIBUNWIND_SUPPORT_SEH_UNWIND or \
2821               _LIBUNWIND_SUPPORT_DWARF_UNWIND or \
2822               _LIBUNWIND_ARM_EHABI
2823 #endif
2824   }
2825 
2826   // update info based on new PC
2827   if (result == UNW_STEP_SUCCESS) {
2828     this->setInfoBasedOnIPRegister(true);
2829     if (_unwindInfoMissing)
2830       return UNW_STEP_END;
2831   }
2832 
2833   return result;
2834 }
2835 
2836 template <typename A, typename R>
2837 void UnwindCursor<A, R>::getInfo(unw_proc_info_t *info) {
2838   if (_unwindInfoMissing)
2839     memset(info, 0, sizeof(*info));
2840   else
2841     *info = _info;
2842 }
2843 
2844 template <typename A, typename R>
2845 bool UnwindCursor<A, R>::getFunctionName(char *buf, size_t bufLen,
2846                                                            unw_word_t *offset) {
2847   return _addressSpace.findFunctionName((pint_t)this->getReg(UNW_REG_IP),
2848                                          buf, bufLen, offset);
2849 }
2850 
2851 #if defined(_LIBUNWIND_USE_CET)
2852 extern "C" void *__libunwind_cet_get_registers(unw_cursor_t *cursor) {
2853   AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
2854   return co->get_registers();
2855 }
2856 #endif
2857 } // namespace libunwind
2858 
2859 #endif // __UNWINDCURSOR_HPP__
2860