1 //===------------------------- UnwindCursor.hpp ---------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //
9 // C++ interface to lower levels of libuwind
10 //===----------------------------------------------------------------------===//
11 
12 #ifndef __UNWINDCURSOR_HPP__
13 #define __UNWINDCURSOR_HPP__
14 
15 #include <algorithm>
16 #include <stdint.h>
17 #include <stdio.h>
18 #include <stdlib.h>
19 #include <pthread.h>
20 #include <unwind.h>
21 
22 #ifdef __APPLE__
23   #include <mach-o/dyld.h>
24 #endif
25 
26 #include "config.h"
27 
28 #include "AddressSpace.hpp"
29 #include "CompactUnwinder.hpp"
30 #include "config.h"
31 #include "DwarfInstructions.hpp"
32 #include "EHHeaderParser.hpp"
33 #include "libunwind.h"
34 #include "Registers.hpp"
35 #include "Unwind-EHABI.h"
36 
37 namespace libunwind {
38 
39 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
40 /// Cache of recently found FDEs.
41 template <typename A>
42 class _LIBUNWIND_HIDDEN DwarfFDECache {
43   typedef typename A::pint_t pint_t;
44 public:
45   static pint_t findFDE(pint_t mh, pint_t pc);
46   static void add(pint_t mh, pint_t ip_start, pint_t ip_end, pint_t fde);
47   static void removeAllIn(pint_t mh);
48   static void iterateCacheEntries(void (*func)(unw_word_t ip_start,
49                                                unw_word_t ip_end,
50                                                unw_word_t fde, unw_word_t mh));
51 
52 private:
53 
54   struct entry {
55     pint_t mh;
56     pint_t ip_start;
57     pint_t ip_end;
58     pint_t fde;
59   };
60 
61   // These fields are all static to avoid needing an initializer.
62   // There is only one instance of this class per process.
63   static pthread_rwlock_t _lock;
64 #ifdef __APPLE__
65   static void dyldUnloadHook(const struct mach_header *mh, intptr_t slide);
66   static bool _registeredForDyldUnloads;
67 #endif
68   // Can't use std::vector<> here because this code is below libc++.
69   static entry *_buffer;
70   static entry *_bufferUsed;
71   static entry *_bufferEnd;
72   static entry _initialBuffer[64];
73 };
74 
75 template <typename A>
76 typename DwarfFDECache<A>::entry *
77 DwarfFDECache<A>::_buffer = _initialBuffer;
78 
79 template <typename A>
80 typename DwarfFDECache<A>::entry *
81 DwarfFDECache<A>::_bufferUsed = _initialBuffer;
82 
83 template <typename A>
84 typename DwarfFDECache<A>::entry *
85 DwarfFDECache<A>::_bufferEnd = &_initialBuffer[64];
86 
87 template <typename A>
88 typename DwarfFDECache<A>::entry DwarfFDECache<A>::_initialBuffer[64];
89 
90 template <typename A>
91 pthread_rwlock_t DwarfFDECache<A>::_lock = PTHREAD_RWLOCK_INITIALIZER;
92 
93 #ifdef __APPLE__
94 template <typename A>
95 bool DwarfFDECache<A>::_registeredForDyldUnloads = false;
96 #endif
97 
98 template <typename A>
findFDE(pint_t mh,pint_t pc)99 typename A::pint_t DwarfFDECache<A>::findFDE(pint_t mh, pint_t pc) {
100   pint_t result = 0;
101   _LIBUNWIND_LOG_NON_ZERO(::pthread_rwlock_rdlock(&_lock));
102   for (entry *p = _buffer; p < _bufferUsed; ++p) {
103     if ((mh == p->mh) || (mh == 0)) {
104       if ((p->ip_start <= pc) && (pc < p->ip_end)) {
105         result = p->fde;
106         break;
107       }
108     }
109   }
110   _LIBUNWIND_LOG_NON_ZERO(::pthread_rwlock_unlock(&_lock));
111   return result;
112 }
113 
114 template <typename A>
add(pint_t mh,pint_t ip_start,pint_t ip_end,pint_t fde)115 void DwarfFDECache<A>::add(pint_t mh, pint_t ip_start, pint_t ip_end,
116                            pint_t fde) {
117   _LIBUNWIND_LOG_NON_ZERO(::pthread_rwlock_wrlock(&_lock));
118   if (_bufferUsed >= _bufferEnd) {
119     size_t oldSize = (size_t)(_bufferEnd - _buffer);
120     size_t newSize = oldSize * 4;
121     // Can't use operator new (we are below it).
122     entry *newBuffer = (entry *)malloc(newSize * sizeof(entry));
123     memcpy(newBuffer, _buffer, oldSize * sizeof(entry));
124     if (_buffer != _initialBuffer)
125       free(_buffer);
126     _buffer = newBuffer;
127     _bufferUsed = &newBuffer[oldSize];
128     _bufferEnd = &newBuffer[newSize];
129   }
130   _bufferUsed->mh = mh;
131   _bufferUsed->ip_start = ip_start;
132   _bufferUsed->ip_end = ip_end;
133   _bufferUsed->fde = fde;
134   ++_bufferUsed;
135 #ifdef __APPLE__
136   if (!_registeredForDyldUnloads) {
137     _dyld_register_func_for_remove_image(&dyldUnloadHook);
138     _registeredForDyldUnloads = true;
139   }
140 #endif
141   _LIBUNWIND_LOG_NON_ZERO(::pthread_rwlock_unlock(&_lock));
142 }
143 
144 template <typename A>
removeAllIn(pint_t mh)145 void DwarfFDECache<A>::removeAllIn(pint_t mh) {
146   _LIBUNWIND_LOG_NON_ZERO(::pthread_rwlock_wrlock(&_lock));
147   entry *d = _buffer;
148   for (const entry *s = _buffer; s < _bufferUsed; ++s) {
149     if (s->mh != mh) {
150       if (d != s)
151         *d = *s;
152       ++d;
153     }
154   }
155   _bufferUsed = d;
156   _LIBUNWIND_LOG_NON_ZERO(::pthread_rwlock_unlock(&_lock));
157 }
158 
159 #ifdef __APPLE__
160 template <typename A>
dyldUnloadHook(const struct mach_header * mh,intptr_t)161 void DwarfFDECache<A>::dyldUnloadHook(const struct mach_header *mh, intptr_t ) {
162   removeAllIn((pint_t) mh);
163 }
164 #endif
165 
166 template <typename A>
iterateCacheEntries(void (* func)(unw_word_t ip_start,unw_word_t ip_end,unw_word_t fde,unw_word_t mh))167 void DwarfFDECache<A>::iterateCacheEntries(void (*func)(
168     unw_word_t ip_start, unw_word_t ip_end, unw_word_t fde, unw_word_t mh)) {
169   _LIBUNWIND_LOG_NON_ZERO(::pthread_rwlock_wrlock(&_lock));
170   for (entry *p = _buffer; p < _bufferUsed; ++p) {
171     (*func)(p->ip_start, p->ip_end, p->fde, p->mh);
172   }
173   _LIBUNWIND_LOG_NON_ZERO(::pthread_rwlock_unlock(&_lock));
174 }
175 #endif // _LIBUNWIND_SUPPORT_DWARF_UNWIND
176 
177 
178 #define arrayoffsetof(type, index, field) ((size_t)(&((type *)0)[index].field))
179 
180 #if _LIBUNWIND_SUPPORT_COMPACT_UNWIND
181 template <typename A> class UnwindSectionHeader {
182 public:
UnwindSectionHeader(A & addressSpace,typename A::pint_t addr)183   UnwindSectionHeader(A &addressSpace, typename A::pint_t addr)
184       : _addressSpace(addressSpace), _addr(addr) {}
185 
version() const186   uint32_t version() const {
187     return _addressSpace.get32(_addr +
188                                offsetof(unwind_info_section_header, version));
189   }
commonEncodingsArraySectionOffset() const190   uint32_t commonEncodingsArraySectionOffset() const {
191     return _addressSpace.get32(_addr +
192                                offsetof(unwind_info_section_header,
193                                         commonEncodingsArraySectionOffset));
194   }
commonEncodingsArrayCount() const195   uint32_t commonEncodingsArrayCount() const {
196     return _addressSpace.get32(_addr + offsetof(unwind_info_section_header,
197                                                 commonEncodingsArrayCount));
198   }
personalityArraySectionOffset() const199   uint32_t personalityArraySectionOffset() const {
200     return _addressSpace.get32(_addr + offsetof(unwind_info_section_header,
201                                                 personalityArraySectionOffset));
202   }
personalityArrayCount() const203   uint32_t personalityArrayCount() const {
204     return _addressSpace.get32(
205         _addr + offsetof(unwind_info_section_header, personalityArrayCount));
206   }
indexSectionOffset() const207   uint32_t indexSectionOffset() const {
208     return _addressSpace.get32(
209         _addr + offsetof(unwind_info_section_header, indexSectionOffset));
210   }
indexCount() const211   uint32_t indexCount() const {
212     return _addressSpace.get32(
213         _addr + offsetof(unwind_info_section_header, indexCount));
214   }
215 
216 private:
217   A                     &_addressSpace;
218   typename A::pint_t     _addr;
219 };
220 
221 template <typename A> class UnwindSectionIndexArray {
222 public:
UnwindSectionIndexArray(A & addressSpace,typename A::pint_t addr)223   UnwindSectionIndexArray(A &addressSpace, typename A::pint_t addr)
224       : _addressSpace(addressSpace), _addr(addr) {}
225 
functionOffset(uint32_t index) const226   uint32_t functionOffset(uint32_t index) const {
227     return _addressSpace.get32(
228         _addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
229                               functionOffset));
230   }
secondLevelPagesSectionOffset(uint32_t index) const231   uint32_t secondLevelPagesSectionOffset(uint32_t index) const {
232     return _addressSpace.get32(
233         _addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
234                               secondLevelPagesSectionOffset));
235   }
lsdaIndexArraySectionOffset(uint32_t index) const236   uint32_t lsdaIndexArraySectionOffset(uint32_t index) const {
237     return _addressSpace.get32(
238         _addr + arrayoffsetof(unwind_info_section_header_index_entry, index,
239                               lsdaIndexArraySectionOffset));
240   }
241 
242 private:
243   A                   &_addressSpace;
244   typename A::pint_t   _addr;
245 };
246 
247 template <typename A> class UnwindSectionRegularPageHeader {
248 public:
UnwindSectionRegularPageHeader(A & addressSpace,typename A::pint_t addr)249   UnwindSectionRegularPageHeader(A &addressSpace, typename A::pint_t addr)
250       : _addressSpace(addressSpace), _addr(addr) {}
251 
kind() const252   uint32_t kind() const {
253     return _addressSpace.get32(
254         _addr + offsetof(unwind_info_regular_second_level_page_header, kind));
255   }
entryPageOffset() const256   uint16_t entryPageOffset() const {
257     return _addressSpace.get16(
258         _addr + offsetof(unwind_info_regular_second_level_page_header,
259                          entryPageOffset));
260   }
entryCount() const261   uint16_t entryCount() const {
262     return _addressSpace.get16(
263         _addr +
264         offsetof(unwind_info_regular_second_level_page_header, entryCount));
265   }
266 
267 private:
268   A &_addressSpace;
269   typename A::pint_t _addr;
270 };
271 
272 template <typename A> class UnwindSectionRegularArray {
273 public:
UnwindSectionRegularArray(A & addressSpace,typename A::pint_t addr)274   UnwindSectionRegularArray(A &addressSpace, typename A::pint_t addr)
275       : _addressSpace(addressSpace), _addr(addr) {}
276 
functionOffset(uint32_t index) const277   uint32_t functionOffset(uint32_t index) const {
278     return _addressSpace.get32(
279         _addr + arrayoffsetof(unwind_info_regular_second_level_entry, index,
280                               functionOffset));
281   }
encoding(uint32_t index) const282   uint32_t encoding(uint32_t index) const {
283     return _addressSpace.get32(
284         _addr +
285         arrayoffsetof(unwind_info_regular_second_level_entry, index, encoding));
286   }
287 
288 private:
289   A &_addressSpace;
290   typename A::pint_t _addr;
291 };
292 
293 template <typename A> class UnwindSectionCompressedPageHeader {
294 public:
UnwindSectionCompressedPageHeader(A & addressSpace,typename A::pint_t addr)295   UnwindSectionCompressedPageHeader(A &addressSpace, typename A::pint_t addr)
296       : _addressSpace(addressSpace), _addr(addr) {}
297 
kind() const298   uint32_t kind() const {
299     return _addressSpace.get32(
300         _addr +
301         offsetof(unwind_info_compressed_second_level_page_header, kind));
302   }
entryPageOffset() const303   uint16_t entryPageOffset() const {
304     return _addressSpace.get16(
305         _addr + offsetof(unwind_info_compressed_second_level_page_header,
306                          entryPageOffset));
307   }
entryCount() const308   uint16_t entryCount() const {
309     return _addressSpace.get16(
310         _addr +
311         offsetof(unwind_info_compressed_second_level_page_header, entryCount));
312   }
encodingsPageOffset() const313   uint16_t encodingsPageOffset() const {
314     return _addressSpace.get16(
315         _addr + offsetof(unwind_info_compressed_second_level_page_header,
316                          encodingsPageOffset));
317   }
encodingsCount() const318   uint16_t encodingsCount() const {
319     return _addressSpace.get16(
320         _addr + offsetof(unwind_info_compressed_second_level_page_header,
321                          encodingsCount));
322   }
323 
324 private:
325   A &_addressSpace;
326   typename A::pint_t _addr;
327 };
328 
329 template <typename A> class UnwindSectionCompressedArray {
330 public:
UnwindSectionCompressedArray(A & addressSpace,typename A::pint_t addr)331   UnwindSectionCompressedArray(A &addressSpace, typename A::pint_t addr)
332       : _addressSpace(addressSpace), _addr(addr) {}
333 
functionOffset(uint32_t index) const334   uint32_t functionOffset(uint32_t index) const {
335     return UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET(
336         _addressSpace.get32(_addr + index * sizeof(uint32_t)));
337   }
encodingIndex(uint32_t index) const338   uint16_t encodingIndex(uint32_t index) const {
339     return UNWIND_INFO_COMPRESSED_ENTRY_ENCODING_INDEX(
340         _addressSpace.get32(_addr + index * sizeof(uint32_t)));
341   }
342 
343 private:
344   A &_addressSpace;
345   typename A::pint_t _addr;
346 };
347 
348 template <typename A> class UnwindSectionLsdaArray {
349 public:
UnwindSectionLsdaArray(A & addressSpace,typename A::pint_t addr)350   UnwindSectionLsdaArray(A &addressSpace, typename A::pint_t addr)
351       : _addressSpace(addressSpace), _addr(addr) {}
352 
functionOffset(uint32_t index) const353   uint32_t functionOffset(uint32_t index) const {
354     return _addressSpace.get32(
355         _addr + arrayoffsetof(unwind_info_section_header_lsda_index_entry,
356                               index, functionOffset));
357   }
lsdaOffset(uint32_t index) const358   uint32_t lsdaOffset(uint32_t index) const {
359     return _addressSpace.get32(
360         _addr + arrayoffsetof(unwind_info_section_header_lsda_index_entry,
361                               index, lsdaOffset));
362   }
363 
364 private:
365   A                   &_addressSpace;
366   typename A::pint_t   _addr;
367 };
368 #endif // _LIBUNWIND_SUPPORT_COMPACT_UNWIND
369 
370 class _LIBUNWIND_HIDDEN AbstractUnwindCursor {
371 public:
372   // NOTE: provide a class specific placement deallocation function (S5.3.4 p20)
373   // This avoids an unnecessary dependency to libc++abi.
operator delete(void *,size_t)374   void operator delete(void *, size_t) {}
375 
~AbstractUnwindCursor()376   virtual ~AbstractUnwindCursor() {}
validReg(int)377   virtual bool validReg(int) { _LIBUNWIND_ABORT("validReg not implemented"); }
getReg(int)378   virtual unw_word_t getReg(int) { _LIBUNWIND_ABORT("getReg not implemented"); }
setReg(int,unw_word_t)379   virtual void setReg(int, unw_word_t) {
380     _LIBUNWIND_ABORT("setReg not implemented");
381   }
validFloatReg(int)382   virtual bool validFloatReg(int) {
383     _LIBUNWIND_ABORT("validFloatReg not implemented");
384   }
getFloatReg(int)385   virtual unw_fpreg_t getFloatReg(int) {
386     _LIBUNWIND_ABORT("getFloatReg not implemented");
387   }
setFloatReg(int,unw_fpreg_t)388   virtual void setFloatReg(int, unw_fpreg_t) {
389     _LIBUNWIND_ABORT("setFloatReg not implemented");
390   }
step()391   virtual int step() { _LIBUNWIND_ABORT("step not implemented"); }
getInfo(unw_proc_info_t *)392   virtual void getInfo(unw_proc_info_t *) {
393     _LIBUNWIND_ABORT("getInfo not implemented");
394   }
jumpto()395   virtual void jumpto() { _LIBUNWIND_ABORT("jumpto not implemented"); }
isSignalFrame()396   virtual bool isSignalFrame() {
397     _LIBUNWIND_ABORT("isSignalFrame not implemented");
398   }
getFunctionName(char *,size_t,unw_word_t *)399   virtual bool getFunctionName(char *, size_t, unw_word_t *) {
400     _LIBUNWIND_ABORT("getFunctionName not implemented");
401   }
setInfoBasedOnIPRegister(bool=false)402   virtual void setInfoBasedOnIPRegister(bool = false) {
403     _LIBUNWIND_ABORT("setInfoBasedOnIPRegister not implemented");
404   }
getRegisterName(int)405   virtual const char *getRegisterName(int) {
406     _LIBUNWIND_ABORT("getRegisterName not implemented");
407   }
408 #ifdef __arm__
saveVFPAsX()409   virtual void saveVFPAsX() { _LIBUNWIND_ABORT("saveVFPAsX not implemented"); }
410 #endif
411 };
412 
413 /// UnwindCursor contains all state (including all register values) during
414 /// an unwind.  This is normally stack allocated inside a unw_cursor_t.
415 template <typename A, typename R>
416 class UnwindCursor : public AbstractUnwindCursor{
417   typedef typename A::pint_t pint_t;
418 public:
419                       UnwindCursor(unw_context_t *context, A &as);
420                       UnwindCursor(A &as, void *threadArg);
~UnwindCursor()421   virtual             ~UnwindCursor() {}
422   virtual bool        validReg(int);
423   virtual unw_word_t  getReg(int);
424   virtual void        setReg(int, unw_word_t);
425   virtual bool        validFloatReg(int);
426   virtual unw_fpreg_t getFloatReg(int);
427   virtual void        setFloatReg(int, unw_fpreg_t);
428   virtual int         step();
429   virtual void        getInfo(unw_proc_info_t *);
430   virtual void        jumpto();
431   virtual bool        isSignalFrame();
432   virtual bool        getFunctionName(char *buf, size_t len, unw_word_t *off);
433   virtual void        setInfoBasedOnIPRegister(bool isReturnAddress = false);
434   virtual const char *getRegisterName(int num);
435 #ifdef __arm__
436   virtual void        saveVFPAsX();
437 #endif
438 
439 private:
440 
441 #if LIBCXXABI_ARM_EHABI
442   bool getInfoFromEHABISection(pint_t pc, const UnwindInfoSections &sects);
443 #endif
444 
445 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
446   bool getInfoFromDwarfSection(pint_t pc, const UnwindInfoSections &sects,
447                                             uint32_t fdeSectionOffsetHint=0);
stepWithDwarfFDE()448   int stepWithDwarfFDE() {
449     return DwarfInstructions<A, R>::stepWithDwarf(_addressSpace,
450                                               (pint_t)this->getReg(UNW_REG_IP),
451                                               (pint_t)_info.unwind_info,
452                                               _registers);
453   }
454 #endif
455 
456 #if _LIBUNWIND_SUPPORT_COMPACT_UNWIND
457   bool getInfoFromCompactEncodingSection(pint_t pc,
458                                             const UnwindInfoSections &sects);
stepWithCompactEncoding()459   int stepWithCompactEncoding() {
460   #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
461     if ( compactSaysUseDwarf() )
462       return stepWithDwarfFDE();
463   #endif
464     R dummy;
465     return stepWithCompactEncoding(dummy);
466   }
467 
stepWithCompactEncoding(Registers_x86_64 &)468   int stepWithCompactEncoding(Registers_x86_64 &) {
469     return CompactUnwinder_x86_64<A>::stepWithCompactEncoding(
470         _info.format, _info.start_ip, _addressSpace, _registers);
471   }
472 
stepWithCompactEncoding(Registers_x86 &)473   int stepWithCompactEncoding(Registers_x86 &) {
474     return CompactUnwinder_x86<A>::stepWithCompactEncoding(
475         _info.format, (uint32_t)_info.start_ip, _addressSpace, _registers);
476   }
477 
stepWithCompactEncoding(Registers_ppc &)478   int stepWithCompactEncoding(Registers_ppc &) {
479     return UNW_EINVAL;
480   }
481 
stepWithCompactEncoding(Registers_arm64 &)482   int stepWithCompactEncoding(Registers_arm64 &) {
483     return CompactUnwinder_arm64<A>::stepWithCompactEncoding(
484         _info.format, _info.start_ip, _addressSpace, _registers);
485   }
486 
compactSaysUseDwarf(uint32_t * offset=NULL) const487   bool compactSaysUseDwarf(uint32_t *offset=NULL) const {
488     R dummy;
489     return compactSaysUseDwarf(dummy, offset);
490   }
491 
compactSaysUseDwarf(Registers_x86_64 &,uint32_t * offset) const492   bool compactSaysUseDwarf(Registers_x86_64 &, uint32_t *offset) const {
493     if ((_info.format & UNWIND_X86_64_MODE_MASK) == UNWIND_X86_64_MODE_DWARF) {
494       if (offset)
495         *offset = (_info.format & UNWIND_X86_64_DWARF_SECTION_OFFSET);
496       return true;
497     }
498     return false;
499   }
500 
compactSaysUseDwarf(Registers_x86 &,uint32_t * offset) const501   bool compactSaysUseDwarf(Registers_x86 &, uint32_t *offset) const {
502     if ((_info.format & UNWIND_X86_MODE_MASK) == UNWIND_X86_MODE_DWARF) {
503       if (offset)
504         *offset = (_info.format & UNWIND_X86_DWARF_SECTION_OFFSET);
505       return true;
506     }
507     return false;
508   }
509 
compactSaysUseDwarf(Registers_ppc &,uint32_t *) const510   bool compactSaysUseDwarf(Registers_ppc &, uint32_t *) const {
511     return true;
512   }
513 
compactSaysUseDwarf(Registers_arm64 &,uint32_t * offset) const514   bool compactSaysUseDwarf(Registers_arm64 &, uint32_t *offset) const {
515     if ((_info.format & UNWIND_ARM64_MODE_MASK) == UNWIND_ARM64_MODE_DWARF) {
516       if (offset)
517         *offset = (_info.format & UNWIND_ARM64_DWARF_SECTION_OFFSET);
518       return true;
519     }
520     return false;
521   }
522 #endif // _LIBUNWIND_SUPPORT_COMPACT_UNWIND
523 
524 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
dwarfEncoding() const525   compact_unwind_encoding_t dwarfEncoding() const {
526     R dummy;
527     return dwarfEncoding(dummy);
528   }
529 
dwarfEncoding(Registers_x86_64 &) const530   compact_unwind_encoding_t dwarfEncoding(Registers_x86_64 &) const {
531     return UNWIND_X86_64_MODE_DWARF;
532   }
533 
dwarfEncoding(Registers_x86 &) const534   compact_unwind_encoding_t dwarfEncoding(Registers_x86 &) const {
535     return UNWIND_X86_MODE_DWARF;
536   }
537 
dwarfEncoding(Registers_ppc &) const538   compact_unwind_encoding_t dwarfEncoding(Registers_ppc &) const {
539     return 0;
540   }
541 
dwarfEncoding(Registers_arm64 &) const542   compact_unwind_encoding_t dwarfEncoding(Registers_arm64 &) const {
543     return UNWIND_ARM64_MODE_DWARF;
544   }
545 #endif // _LIBUNWIND_SUPPORT_DWARF_UNWIND
546 
547 
548   A               &_addressSpace;
549   R                _registers;
550   unw_proc_info_t  _info;
551   bool             _unwindInfoMissing;
552   bool             _isSignalFrame;
553 };
554 
555 
556 template <typename A, typename R>
UnwindCursor(unw_context_t * context,A & as)557 UnwindCursor<A, R>::UnwindCursor(unw_context_t *context, A &as)
558     : _addressSpace(as), _registers(context), _unwindInfoMissing(false),
559       _isSignalFrame(false) {
560   static_assert(sizeof(UnwindCursor<A, R>) < sizeof(unw_cursor_t),
561                 "UnwindCursor<> does not fit in unw_cursor_t");
562   memset(&_info, 0, sizeof(_info));
563 }
564 
565 template <typename A, typename R>
UnwindCursor(A & as,void *)566 UnwindCursor<A, R>::UnwindCursor(A &as, void *)
567     : _addressSpace(as), _unwindInfoMissing(false), _isSignalFrame(false) {
568   memset(&_info, 0, sizeof(_info));
569   // FIXME
570   // fill in _registers from thread arg
571 }
572 
573 
574 template <typename A, typename R>
validReg(int regNum)575 bool UnwindCursor<A, R>::validReg(int regNum) {
576   return _registers.validRegister(regNum);
577 }
578 
579 template <typename A, typename R>
getReg(int regNum)580 unw_word_t UnwindCursor<A, R>::getReg(int regNum) {
581   return _registers.getRegister(regNum);
582 }
583 
584 template <typename A, typename R>
setReg(int regNum,unw_word_t value)585 void UnwindCursor<A, R>::setReg(int regNum, unw_word_t value) {
586   _registers.setRegister(regNum, (typename A::pint_t)value);
587 }
588 
589 template <typename A, typename R>
validFloatReg(int regNum)590 bool UnwindCursor<A, R>::validFloatReg(int regNum) {
591   return _registers.validFloatRegister(regNum);
592 }
593 
594 template <typename A, typename R>
getFloatReg(int regNum)595 unw_fpreg_t UnwindCursor<A, R>::getFloatReg(int regNum) {
596   return _registers.getFloatRegister(regNum);
597 }
598 
599 template <typename A, typename R>
setFloatReg(int regNum,unw_fpreg_t value)600 void UnwindCursor<A, R>::setFloatReg(int regNum, unw_fpreg_t value) {
601   _registers.setFloatRegister(regNum, value);
602 }
603 
jumpto()604 template <typename A, typename R> void UnwindCursor<A, R>::jumpto() {
605   _registers.jumpto();
606 }
607 
608 #ifdef __arm__
saveVFPAsX()609 template <typename A, typename R> void UnwindCursor<A, R>::saveVFPAsX() {
610   _registers.saveVFPAsX();
611 }
612 #endif
613 
614 template <typename A, typename R>
getRegisterName(int regNum)615 const char *UnwindCursor<A, R>::getRegisterName(int regNum) {
616   return _registers.getRegisterName(regNum);
617 }
618 
isSignalFrame()619 template <typename A, typename R> bool UnwindCursor<A, R>::isSignalFrame() {
620   return _isSignalFrame;
621 }
622 
623 #if LIBCXXABI_ARM_EHABI
624 struct EHABIIndexEntry {
625   uint32_t functionOffset;
626   uint32_t data;
627 };
628 
629 template<typename A>
630 struct EHABISectionIterator {
631   typedef EHABISectionIterator _Self;
632 
633   typedef std::random_access_iterator_tag iterator_category;
634   typedef typename A::pint_t value_type;
635   typedef typename A::pint_t* pointer;
636   typedef typename A::pint_t& reference;
637   typedef size_t size_type;
638   typedef size_t difference_type;
639 
beginlibunwind::EHABISectionIterator640   static _Self begin(A& addressSpace, const UnwindInfoSections& sects) {
641     return _Self(addressSpace, sects, 0);
642   }
endlibunwind::EHABISectionIterator643   static _Self end(A& addressSpace, const UnwindInfoSections& sects) {
644     return _Self(addressSpace, sects, sects.arm_section_length);
645   }
646 
EHABISectionIteratorlibunwind::EHABISectionIterator647   EHABISectionIterator(A& addressSpace, const UnwindInfoSections& sects, size_t i)
648       : _i(i), _addressSpace(&addressSpace), _sects(&sects) {}
649 
operator ++libunwind::EHABISectionIterator650   _Self& operator++() { ++_i; return *this; }
operator +=libunwind::EHABISectionIterator651   _Self& operator+=(size_t a) { _i += a; return *this; }
operator --libunwind::EHABISectionIterator652   _Self& operator--() { assert(_i > 0); --_i; return *this; }
operator -=libunwind::EHABISectionIterator653   _Self& operator-=(size_t a) { assert(_i >= a); _i -= a; return *this; }
654 
operator +libunwind::EHABISectionIterator655   _Self operator+(size_t a) { _Self out = *this; out._i += a; return out; }
operator -libunwind::EHABISectionIterator656   _Self operator-(size_t a) { assert(_i >= a); _Self out = *this; out._i -= a; return out; }
657 
operator -libunwind::EHABISectionIterator658   size_t operator-(const _Self& other) { return _i - other._i; }
659 
operator ==libunwind::EHABISectionIterator660   bool operator==(const _Self& other) const {
661     assert(_addressSpace == other._addressSpace);
662     assert(_sects == other._sects);
663     return _i == other._i;
664   }
665 
operator *libunwind::EHABISectionIterator666   typename A::pint_t operator*() const { return functionAddress(); }
667 
functionAddresslibunwind::EHABISectionIterator668   typename A::pint_t functionAddress() const {
669     typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
670         EHABIIndexEntry, _i, functionOffset);
671     return indexAddr + signExtendPrel31(_addressSpace->get32(indexAddr));
672   }
673 
dataAddresslibunwind::EHABISectionIterator674   typename A::pint_t dataAddress() {
675     typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
676         EHABIIndexEntry, _i, data);
677     return indexAddr;
678   }
679 
680  private:
681   size_t _i;
682   A* _addressSpace;
683   const UnwindInfoSections* _sects;
684 };
685 
686 template <typename A, typename R>
getInfoFromEHABISection(pint_t pc,const UnwindInfoSections & sects)687 bool UnwindCursor<A, R>::getInfoFromEHABISection(
688     pint_t pc,
689     const UnwindInfoSections &sects) {
690   EHABISectionIterator<A> begin =
691       EHABISectionIterator<A>::begin(_addressSpace, sects);
692   EHABISectionIterator<A> end =
693       EHABISectionIterator<A>::end(_addressSpace, sects);
694 
695   EHABISectionIterator<A> itNextPC = std::upper_bound(begin, end, pc);
696   if (itNextPC == begin || itNextPC == end)
697     return false;
698   EHABISectionIterator<A> itThisPC = itNextPC - 1;
699 
700   pint_t thisPC = itThisPC.functionAddress();
701   pint_t nextPC = itNextPC.functionAddress();
702   pint_t indexDataAddr = itThisPC.dataAddress();
703 
704   if (indexDataAddr == 0)
705     return false;
706 
707   uint32_t indexData = _addressSpace.get32(indexDataAddr);
708   if (indexData == UNW_EXIDX_CANTUNWIND)
709     return false;
710 
711   // If the high bit is set, the exception handling table entry is inline inside
712   // the index table entry on the second word (aka |indexDataAddr|). Otherwise,
713   // the table points at an offset in the exception handling table (section 5 EHABI).
714   pint_t exceptionTableAddr;
715   uint32_t exceptionTableData;
716   bool isSingleWordEHT;
717   if (indexData & 0x80000000) {
718     exceptionTableAddr = indexDataAddr;
719     // TODO(ajwong): Should this data be 0?
720     exceptionTableData = indexData;
721     isSingleWordEHT = true;
722   } else {
723     exceptionTableAddr = indexDataAddr + signExtendPrel31(indexData);
724     exceptionTableData = _addressSpace.get32(exceptionTableAddr);
725     isSingleWordEHT = false;
726   }
727 
728   // Now we know the 3 things:
729   //   exceptionTableAddr -- exception handler table entry.
730   //   exceptionTableData -- the data inside the first word of the eht entry.
731   //   isSingleWordEHT -- whether the entry is in the index.
732   unw_word_t personalityRoutine = 0xbadf00d;
733   bool scope32 = false;
734   uintptr_t lsda = 0xbadf00d;
735 
736   // If the high bit in the exception handling table entry is set, the entry is
737   // in compact form (section 6.3 EHABI).
738   if (exceptionTableData & 0x80000000) {
739     // Grab the index of the personality routine from the compact form.
740     uint32_t choice = (exceptionTableData & 0x0f000000) >> 24;
741     uint32_t extraWords = 0;
742     switch (choice) {
743       case 0:
744         personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr0;
745         extraWords = 0;
746         scope32 = false;
747         break;
748       case 1:
749         personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr1;
750         extraWords = (exceptionTableData & 0x00ff0000) >> 16;
751         scope32 = false;
752         break;
753       case 2:
754         personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr2;
755         extraWords = (exceptionTableData & 0x00ff0000) >> 16;
756         scope32 = true;
757         break;
758       default:
759         _LIBUNWIND_ABORT("unknown personality routine");
760         return false;
761     }
762 
763     if (isSingleWordEHT) {
764       if (extraWords != 0) {
765         _LIBUNWIND_ABORT("index inlined table detected but pr function "
766                          "requires extra words");
767         return false;
768       }
769     }
770   } else {
771     pint_t personalityAddr =
772         exceptionTableAddr + signExtendPrel31(exceptionTableData);
773     personalityRoutine = personalityAddr;
774 
775     // ARM EHABI # 6.2, # 9.2
776     //
777     //  +---- ehtp
778     //  v
779     // +--------------------------------------+
780     // | +--------+--------+--------+-------+ |
781     // | |0| prel31 to personalityRoutine   | |
782     // | +--------+--------+--------+-------+ |
783     // | |      N |      unwind opcodes     | |  <-- UnwindData
784     // | +--------+--------+--------+-------+ |
785     // | | Word 2        unwind opcodes     | |
786     // | +--------+--------+--------+-------+ |
787     // | ...                                  |
788     // | +--------+--------+--------+-------+ |
789     // | | Word N        unwind opcodes     | |
790     // | +--------+--------+--------+-------+ |
791     // | | LSDA                             | |  <-- lsda
792     // | | ...                              | |
793     // | +--------+--------+--------+-------+ |
794     // +--------------------------------------+
795 
796     uint32_t *UnwindData = reinterpret_cast<uint32_t*>(exceptionTableAddr) + 1;
797     uint32_t FirstDataWord = *UnwindData;
798     size_t N = ((FirstDataWord >> 24) & 0xff);
799     size_t NDataWords = N + 1;
800     lsda = reinterpret_cast<uintptr_t>(UnwindData + NDataWords);
801   }
802 
803   _info.start_ip = thisPC;
804   _info.end_ip = nextPC;
805   _info.handler = personalityRoutine;
806   _info.unwind_info = exceptionTableAddr;
807   _info.lsda = lsda;
808   // flags is pr_cache.additional. See EHABI #7.2 for definition of bit 0.
809   _info.flags = isSingleWordEHT ? 1 : 0 | scope32 ? 0x2 : 0;  // Use enum?
810 
811   return true;
812 }
813 #endif
814 
815 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
816 template <typename A, typename R>
getInfoFromDwarfSection(pint_t pc,const UnwindInfoSections & sects,uint32_t fdeSectionOffsetHint)817 bool UnwindCursor<A, R>::getInfoFromDwarfSection(pint_t pc,
818                                                 const UnwindInfoSections &sects,
819                                                 uint32_t fdeSectionOffsetHint) {
820   typename CFI_Parser<A>::FDE_Info fdeInfo;
821   typename CFI_Parser<A>::CIE_Info cieInfo;
822   bool foundFDE = false;
823   bool foundInCache = false;
824   // If compact encoding table gave offset into dwarf section, go directly there
825   if (fdeSectionOffsetHint != 0) {
826     foundFDE = CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
827                                     (uint32_t)sects.dwarf_section_length,
828                                     sects.dwarf_section + fdeSectionOffsetHint,
829                                     &fdeInfo, &cieInfo);
830   }
831 #if _LIBUNWIND_SUPPORT_DWARF_INDEX
832   if (!foundFDE && (sects.dwarf_index_section != 0)) {
833     foundFDE = EHHeaderParser<A>::findFDE(
834         _addressSpace, pc, sects.dwarf_index_section,
835         (uint32_t)sects.dwarf_index_section_length, &fdeInfo, &cieInfo);
836   }
837 #endif
838   if (!foundFDE) {
839     // otherwise, search cache of previously found FDEs.
840     pint_t cachedFDE = DwarfFDECache<A>::findFDE(sects.dso_base, pc);
841     if (cachedFDE != 0) {
842       foundFDE =
843           CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
844                                  (uint32_t)sects.dwarf_section_length,
845                                  cachedFDE, &fdeInfo, &cieInfo);
846       foundInCache = foundFDE;
847     }
848   }
849   if (!foundFDE) {
850     // Still not found, do full scan of __eh_frame section.
851     foundFDE = CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
852                                       (uint32_t)sects.dwarf_section_length, 0,
853                                       &fdeInfo, &cieInfo);
854   }
855   if (foundFDE) {
856     typename CFI_Parser<A>::PrologInfo prolog;
857     if (CFI_Parser<A>::parseFDEInstructions(_addressSpace, fdeInfo, cieInfo, pc,
858                                             &prolog)) {
859       // Save off parsed FDE info
860       _info.start_ip          = fdeInfo.pcStart;
861       _info.end_ip            = fdeInfo.pcEnd;
862       _info.lsda              = fdeInfo.lsda;
863       _info.handler           = cieInfo.personality;
864       _info.gp                = prolog.spExtraArgSize;
865       _info.flags             = 0;
866       _info.format            = dwarfEncoding();
867       _info.unwind_info       = fdeInfo.fdeStart;
868       _info.unwind_info_size  = (uint32_t)fdeInfo.fdeLength;
869       _info.extra             = (unw_word_t) sects.dso_base;
870 
871       // Add to cache (to make next lookup faster) if we had no hint
872       // and there was no index.
873       if (!foundInCache && (fdeSectionOffsetHint == 0)) {
874   #if _LIBUNWIND_SUPPORT_DWARF_INDEX
875         if (sects.dwarf_index_section == 0)
876   #endif
877         DwarfFDECache<A>::add(sects.dso_base, fdeInfo.pcStart, fdeInfo.pcEnd,
878                               fdeInfo.fdeStart);
879       }
880       return true;
881     }
882   }
883   //_LIBUNWIND_DEBUG_LOG("can't find/use FDE for pc=0x%llX\n", (uint64_t)pc);
884   return false;
885 }
886 #endif // _LIBUNWIND_SUPPORT_DWARF_UNWIND
887 
888 
889 #if _LIBUNWIND_SUPPORT_COMPACT_UNWIND
890 template <typename A, typename R>
getInfoFromCompactEncodingSection(pint_t pc,const UnwindInfoSections & sects)891 bool UnwindCursor<A, R>::getInfoFromCompactEncodingSection(pint_t pc,
892                                               const UnwindInfoSections &sects) {
893   const bool log = false;
894   if (log)
895     fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX, mh=0x%llX)\n",
896             (uint64_t)pc, (uint64_t)sects.dso_base);
897 
898   const UnwindSectionHeader<A> sectionHeader(_addressSpace,
899                                                 sects.compact_unwind_section);
900   if (sectionHeader.version() != UNWIND_SECTION_VERSION)
901     return false;
902 
903   // do a binary search of top level index to find page with unwind info
904   pint_t targetFunctionOffset = pc - sects.dso_base;
905   const UnwindSectionIndexArray<A> topIndex(_addressSpace,
906                                            sects.compact_unwind_section
907                                          + sectionHeader.indexSectionOffset());
908   uint32_t low = 0;
909   uint32_t high = sectionHeader.indexCount();
910   uint32_t last = high - 1;
911   while (low < high) {
912     uint32_t mid = (low + high) / 2;
913     //if ( log ) fprintf(stderr, "\tmid=%d, low=%d, high=%d, *mid=0x%08X\n",
914     //mid, low, high, topIndex.functionOffset(mid));
915     if (topIndex.functionOffset(mid) <= targetFunctionOffset) {
916       if ((mid == last) ||
917           (topIndex.functionOffset(mid + 1) > targetFunctionOffset)) {
918         low = mid;
919         break;
920       } else {
921         low = mid + 1;
922       }
923     } else {
924       high = mid;
925     }
926   }
927   const uint32_t firstLevelFunctionOffset = topIndex.functionOffset(low);
928   const uint32_t firstLevelNextPageFunctionOffset =
929       topIndex.functionOffset(low + 1);
930   const pint_t secondLevelAddr =
931       sects.compact_unwind_section + topIndex.secondLevelPagesSectionOffset(low);
932   const pint_t lsdaArrayStartAddr =
933       sects.compact_unwind_section + topIndex.lsdaIndexArraySectionOffset(low);
934   const pint_t lsdaArrayEndAddr =
935       sects.compact_unwind_section + topIndex.lsdaIndexArraySectionOffset(low+1);
936   if (log)
937     fprintf(stderr, "\tfirst level search for result index=%d "
938                     "to secondLevelAddr=0x%llX\n",
939                     low, (uint64_t) secondLevelAddr);
940   // do a binary search of second level page index
941   uint32_t encoding = 0;
942   pint_t funcStart = 0;
943   pint_t funcEnd = 0;
944   pint_t lsda = 0;
945   pint_t personality = 0;
946   uint32_t pageKind = _addressSpace.get32(secondLevelAddr);
947   if (pageKind == UNWIND_SECOND_LEVEL_REGULAR) {
948     // regular page
949     UnwindSectionRegularPageHeader<A> pageHeader(_addressSpace,
950                                                  secondLevelAddr);
951     UnwindSectionRegularArray<A> pageIndex(
952         _addressSpace, secondLevelAddr + pageHeader.entryPageOffset());
953     // binary search looks for entry with e where index[e].offset <= pc <
954     // index[e+1].offset
955     if (log)
956       fprintf(stderr, "\tbinary search for targetFunctionOffset=0x%08llX in "
957                       "regular page starting at secondLevelAddr=0x%llX\n",
958               (uint64_t) targetFunctionOffset, (uint64_t) secondLevelAddr);
959     low = 0;
960     high = pageHeader.entryCount();
961     while (low < high) {
962       uint32_t mid = (low + high) / 2;
963       if (pageIndex.functionOffset(mid) <= targetFunctionOffset) {
964         if (mid == (uint32_t)(pageHeader.entryCount() - 1)) {
965           // at end of table
966           low = mid;
967           funcEnd = firstLevelNextPageFunctionOffset + sects.dso_base;
968           break;
969         } else if (pageIndex.functionOffset(mid + 1) > targetFunctionOffset) {
970           // next is too big, so we found it
971           low = mid;
972           funcEnd = pageIndex.functionOffset(low + 1) + sects.dso_base;
973           break;
974         } else {
975           low = mid + 1;
976         }
977       } else {
978         high = mid;
979       }
980     }
981     encoding = pageIndex.encoding(low);
982     funcStart = pageIndex.functionOffset(low) + sects.dso_base;
983     if (pc < funcStart) {
984       if (log)
985         fprintf(
986             stderr,
987             "\tpc not in table, pc=0x%llX, funcStart=0x%llX, funcEnd=0x%llX\n",
988             (uint64_t) pc, (uint64_t) funcStart, (uint64_t) funcEnd);
989       return false;
990     }
991     if (pc > funcEnd) {
992       if (log)
993         fprintf(
994             stderr,
995             "\tpc not in table, pc=0x%llX, funcStart=0x%llX, funcEnd=0x%llX\n",
996             (uint64_t) pc, (uint64_t) funcStart, (uint64_t) funcEnd);
997       return false;
998     }
999   } else if (pageKind == UNWIND_SECOND_LEVEL_COMPRESSED) {
1000     // compressed page
1001     UnwindSectionCompressedPageHeader<A> pageHeader(_addressSpace,
1002                                                     secondLevelAddr);
1003     UnwindSectionCompressedArray<A> pageIndex(
1004         _addressSpace, secondLevelAddr + pageHeader.entryPageOffset());
1005     const uint32_t targetFunctionPageOffset =
1006         (uint32_t)(targetFunctionOffset - firstLevelFunctionOffset);
1007     // binary search looks for entry with e where index[e].offset <= pc <
1008     // index[e+1].offset
1009     if (log)
1010       fprintf(stderr, "\tbinary search of compressed page starting at "
1011                       "secondLevelAddr=0x%llX\n",
1012               (uint64_t) secondLevelAddr);
1013     low = 0;
1014     last = pageHeader.entryCount() - 1;
1015     high = pageHeader.entryCount();
1016     while (low < high) {
1017       uint32_t mid = (low + high) / 2;
1018       if (pageIndex.functionOffset(mid) <= targetFunctionPageOffset) {
1019         if ((mid == last) ||
1020             (pageIndex.functionOffset(mid + 1) > targetFunctionPageOffset)) {
1021           low = mid;
1022           break;
1023         } else {
1024           low = mid + 1;
1025         }
1026       } else {
1027         high = mid;
1028       }
1029     }
1030     funcStart = pageIndex.functionOffset(low) + firstLevelFunctionOffset
1031                                                               + sects.dso_base;
1032     if (low < last)
1033       funcEnd =
1034           pageIndex.functionOffset(low + 1) + firstLevelFunctionOffset
1035                                                               + sects.dso_base;
1036     else
1037       funcEnd = firstLevelNextPageFunctionOffset + sects.dso_base;
1038     if (pc < funcStart) {
1039       _LIBUNWIND_DEBUG_LOG("malformed __unwind_info, pc=0x%llX not in second  "
1040                            "level compressed unwind table. funcStart=0x%llX\n",
1041                             (uint64_t) pc, (uint64_t) funcStart);
1042       return false;
1043     }
1044     if (pc > funcEnd) {
1045       _LIBUNWIND_DEBUG_LOG("malformed __unwind_info, pc=0x%llX not in second  "
1046                           "level compressed unwind table. funcEnd=0x%llX\n",
1047                            (uint64_t) pc, (uint64_t) funcEnd);
1048       return false;
1049     }
1050     uint16_t encodingIndex = pageIndex.encodingIndex(low);
1051     if (encodingIndex < sectionHeader.commonEncodingsArrayCount()) {
1052       // encoding is in common table in section header
1053       encoding = _addressSpace.get32(
1054           sects.compact_unwind_section +
1055           sectionHeader.commonEncodingsArraySectionOffset() +
1056           encodingIndex * sizeof(uint32_t));
1057     } else {
1058       // encoding is in page specific table
1059       uint16_t pageEncodingIndex =
1060           encodingIndex - (uint16_t)sectionHeader.commonEncodingsArrayCount();
1061       encoding = _addressSpace.get32(secondLevelAddr +
1062                                      pageHeader.encodingsPageOffset() +
1063                                      pageEncodingIndex * sizeof(uint32_t));
1064     }
1065   } else {
1066     _LIBUNWIND_DEBUG_LOG("malformed __unwind_info at 0x%0llX bad second "
1067                          "level page\n",
1068                           (uint64_t) sects.compact_unwind_section);
1069     return false;
1070   }
1071 
1072   // look up LSDA, if encoding says function has one
1073   if (encoding & UNWIND_HAS_LSDA) {
1074     UnwindSectionLsdaArray<A> lsdaIndex(_addressSpace, lsdaArrayStartAddr);
1075     uint32_t funcStartOffset = (uint32_t)(funcStart - sects.dso_base);
1076     low = 0;
1077     high = (uint32_t)(lsdaArrayEndAddr - lsdaArrayStartAddr) /
1078                     sizeof(unwind_info_section_header_lsda_index_entry);
1079     // binary search looks for entry with exact match for functionOffset
1080     if (log)
1081       fprintf(stderr,
1082               "\tbinary search of lsda table for targetFunctionOffset=0x%08X\n",
1083               funcStartOffset);
1084     while (low < high) {
1085       uint32_t mid = (low + high) / 2;
1086       if (lsdaIndex.functionOffset(mid) == funcStartOffset) {
1087         lsda = lsdaIndex.lsdaOffset(mid) + sects.dso_base;
1088         break;
1089       } else if (lsdaIndex.functionOffset(mid) < funcStartOffset) {
1090         low = mid + 1;
1091       } else {
1092         high = mid;
1093       }
1094     }
1095     if (lsda == 0) {
1096       _LIBUNWIND_DEBUG_LOG("found encoding 0x%08X with HAS_LSDA bit set for "
1097                     "pc=0x%0llX, but lsda table has no entry\n",
1098                     encoding, (uint64_t) pc);
1099       return false;
1100     }
1101   }
1102 
1103   // extact personality routine, if encoding says function has one
1104   uint32_t personalityIndex = (encoding & UNWIND_PERSONALITY_MASK) >>
1105                               (__builtin_ctz(UNWIND_PERSONALITY_MASK));
1106   if (personalityIndex != 0) {
1107     --personalityIndex; // change 1-based to zero-based index
1108     if (personalityIndex > sectionHeader.personalityArrayCount()) {
1109       _LIBUNWIND_DEBUG_LOG("found encoding 0x%08X with personality index %d,  "
1110                             "but personality table has only %d entires\n",
1111                             encoding, personalityIndex,
1112                             sectionHeader.personalityArrayCount());
1113       return false;
1114     }
1115     int32_t personalityDelta = (int32_t)_addressSpace.get32(
1116         sects.compact_unwind_section +
1117         sectionHeader.personalityArraySectionOffset() +
1118         personalityIndex * sizeof(uint32_t));
1119     pint_t personalityPointer = sects.dso_base + (pint_t)personalityDelta;
1120     personality = _addressSpace.getP(personalityPointer);
1121     if (log)
1122       fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX), "
1123                       "personalityDelta=0x%08X, personality=0x%08llX\n",
1124               (uint64_t) pc, personalityDelta, (uint64_t) personality);
1125   }
1126 
1127   if (log)
1128     fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX), "
1129                     "encoding=0x%08X, lsda=0x%08llX for funcStart=0x%llX\n",
1130             (uint64_t) pc, encoding, (uint64_t) lsda, (uint64_t) funcStart);
1131   _info.start_ip = funcStart;
1132   _info.end_ip = funcEnd;
1133   _info.lsda = lsda;
1134   _info.handler = personality;
1135   _info.gp = 0;
1136   _info.flags = 0;
1137   _info.format = encoding;
1138   _info.unwind_info = 0;
1139   _info.unwind_info_size = 0;
1140   _info.extra = sects.dso_base;
1141   return true;
1142 }
1143 #endif // _LIBUNWIND_SUPPORT_COMPACT_UNWIND
1144 
1145 
1146 template <typename A, typename R>
setInfoBasedOnIPRegister(bool isReturnAddress)1147 void UnwindCursor<A, R>::setInfoBasedOnIPRegister(bool isReturnAddress) {
1148   pint_t pc = (pint_t)this->getReg(UNW_REG_IP);
1149 #if LIBCXXABI_ARM_EHABI
1150   // Remove the thumb bit so the IP represents the actual instruction address.
1151   // This matches the behaviour of _Unwind_GetIP on arm.
1152   pc &= (pint_t)~0x1;
1153 #endif
1154 
1155   // If the last line of a function is a "throw" the compiler sometimes
1156   // emits no instructions after the call to __cxa_throw.  This means
1157   // the return address is actually the start of the next function.
1158   // To disambiguate this, back up the pc when we know it is a return
1159   // address.
1160   if (isReturnAddress)
1161     --pc;
1162 
1163   // Ask address space object to find unwind sections for this pc.
1164   UnwindInfoSections sects;
1165   if (_addressSpace.findUnwindSections(pc, sects)) {
1166 #if _LIBUNWIND_SUPPORT_COMPACT_UNWIND
1167     // If there is a compact unwind encoding table, look there first.
1168     if (sects.compact_unwind_section != 0) {
1169       if (this->getInfoFromCompactEncodingSection(pc, sects)) {
1170   #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
1171         // Found info in table, done unless encoding says to use dwarf.
1172         uint32_t dwarfOffset;
1173         if ((sects.dwarf_section != 0) && compactSaysUseDwarf(&dwarfOffset)) {
1174           if (this->getInfoFromDwarfSection(pc, sects, dwarfOffset)) {
1175             // found info in dwarf, done
1176             return;
1177           }
1178         }
1179   #endif
1180         // If unwind table has entry, but entry says there is no unwind info,
1181         // record that we have no unwind info.
1182         if (_info.format == 0)
1183           _unwindInfoMissing = true;
1184         return;
1185       }
1186     }
1187 #endif // _LIBUNWIND_SUPPORT_COMPACT_UNWIND
1188 
1189 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
1190     // If there is dwarf unwind info, look there next.
1191     if (sects.dwarf_section != 0) {
1192       if (this->getInfoFromDwarfSection(pc, sects)) {
1193         // found info in dwarf, done
1194         return;
1195       }
1196     }
1197 #endif
1198 
1199 #if LIBCXXABI_ARM_EHABI
1200     // If there is ARM EHABI unwind info, look there next.
1201     if (sects.arm_section != 0 && this->getInfoFromEHABISection(pc, sects))
1202       return;
1203 #endif
1204   }
1205 
1206 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
1207   // There is no static unwind info for this pc. Look to see if an FDE was
1208   // dynamically registered for it.
1209   pint_t cachedFDE = DwarfFDECache<A>::findFDE(0, pc);
1210   if (cachedFDE != 0) {
1211     CFI_Parser<LocalAddressSpace>::FDE_Info fdeInfo;
1212     CFI_Parser<LocalAddressSpace>::CIE_Info cieInfo;
1213     const char *msg = CFI_Parser<A>::decodeFDE(_addressSpace,
1214                                                 cachedFDE, &fdeInfo, &cieInfo);
1215     if (msg == NULL) {
1216       typename CFI_Parser<A>::PrologInfo prolog;
1217       if (CFI_Parser<A>::parseFDEInstructions(_addressSpace, fdeInfo, cieInfo,
1218                                                                 pc, &prolog)) {
1219         // save off parsed FDE info
1220         _info.start_ip         = fdeInfo.pcStart;
1221         _info.end_ip           = fdeInfo.pcEnd;
1222         _info.lsda             = fdeInfo.lsda;
1223         _info.handler          = cieInfo.personality;
1224         _info.gp               = prolog.spExtraArgSize;
1225                                   // Some frameless functions need SP
1226                                   // altered when resuming in function.
1227         _info.flags            = 0;
1228         _info.format           = dwarfEncoding();
1229         _info.unwind_info      = fdeInfo.fdeStart;
1230         _info.unwind_info_size = (uint32_t)fdeInfo.fdeLength;
1231         _info.extra            = 0;
1232         return;
1233       }
1234     }
1235   }
1236 
1237   // Lastly, ask AddressSpace object about platform specific ways to locate
1238   // other FDEs.
1239   pint_t fde;
1240   if (_addressSpace.findOtherFDE(pc, fde)) {
1241     CFI_Parser<LocalAddressSpace>::FDE_Info fdeInfo;
1242     CFI_Parser<LocalAddressSpace>::CIE_Info cieInfo;
1243     if (!CFI_Parser<A>::decodeFDE(_addressSpace, fde, &fdeInfo, &cieInfo)) {
1244       // Double check this FDE is for a function that includes the pc.
1245       if ((fdeInfo.pcStart <= pc) && (pc < fdeInfo.pcEnd)) {
1246         typename CFI_Parser<A>::PrologInfo prolog;
1247         if (CFI_Parser<A>::parseFDEInstructions(_addressSpace, fdeInfo,
1248                                                 cieInfo, pc, &prolog)) {
1249           // save off parsed FDE info
1250           _info.start_ip         = fdeInfo.pcStart;
1251           _info.end_ip           = fdeInfo.pcEnd;
1252           _info.lsda             = fdeInfo.lsda;
1253           _info.handler          = cieInfo.personality;
1254           _info.gp               = prolog.spExtraArgSize;
1255           _info.flags            = 0;
1256           _info.format           = dwarfEncoding();
1257           _info.unwind_info      = fdeInfo.fdeStart;
1258           _info.unwind_info_size = (uint32_t)fdeInfo.fdeLength;
1259           _info.extra            = 0;
1260           return;
1261         }
1262       }
1263     }
1264   }
1265 #endif // #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
1266 
1267   // no unwind info, flag that we can't reliably unwind
1268   _unwindInfoMissing = true;
1269 }
1270 
1271 template <typename A, typename R>
step()1272 int UnwindCursor<A, R>::step() {
1273   // Bottom of stack is defined is when unwind info cannot be found.
1274   if (_unwindInfoMissing)
1275     return UNW_STEP_END;
1276 
1277   // Use unwinding info to modify register set as if function returned.
1278   int result;
1279 #if _LIBUNWIND_SUPPORT_COMPACT_UNWIND
1280   result = this->stepWithCompactEncoding();
1281 #elif _LIBUNWIND_SUPPORT_DWARF_UNWIND
1282   result = this->stepWithDwarfFDE();
1283 #elif LIBCXXABI_ARM_EHABI
1284   result = UNW_STEP_SUCCESS;
1285 #else
1286   #error Need _LIBUNWIND_SUPPORT_COMPACT_UNWIND or \
1287               _LIBUNWIND_SUPPORT_DWARF_UNWIND or \
1288               LIBCXXABI_ARM_EHABI
1289 #endif
1290 
1291   // update info based on new PC
1292   if (result == UNW_STEP_SUCCESS) {
1293     this->setInfoBasedOnIPRegister(true);
1294     if (_unwindInfoMissing)
1295       return UNW_STEP_END;
1296     if (_info.gp)
1297       setReg(UNW_REG_SP, getReg(UNW_REG_SP) + _info.gp);
1298   }
1299 
1300   return result;
1301 }
1302 
1303 template <typename A, typename R>
getInfo(unw_proc_info_t * info)1304 void UnwindCursor<A, R>::getInfo(unw_proc_info_t *info) {
1305   *info = _info;
1306 }
1307 
1308 template <typename A, typename R>
getFunctionName(char * buf,size_t bufLen,unw_word_t * offset)1309 bool UnwindCursor<A, R>::getFunctionName(char *buf, size_t bufLen,
1310                                                            unw_word_t *offset) {
1311   return _addressSpace.findFunctionName((pint_t)this->getReg(UNW_REG_IP),
1312                                          buf, bufLen, offset);
1313 }
1314 
1315 } // namespace libunwind
1316 
1317 #endif // __UNWINDCURSOR_HPP__
1318