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 _LIBUNWIND_ARM_EHABI
442   bool getInfoFromEHABISection(pint_t pc, const UnwindInfoSections &sects);
443 
stepWithEHABI()444   int stepWithEHABI() {
445     size_t len = 0;
446     size_t off = 0;
447     // FIXME: Calling decode_eht_entry() here is violating the libunwind
448     // abstraction layer.
449     const uint32_t *ehtp =
450         decode_eht_entry(reinterpret_cast<const uint32_t *>(_info.unwind_info),
451                          &off, &len);
452     if (_Unwind_VRS_Interpret((_Unwind_Context *)this, ehtp, off, len) !=
453             _URC_CONTINUE_UNWIND)
454       return UNW_STEP_END;
455     return UNW_STEP_SUCCESS;
456   }
457 #endif
458 
459 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
460   bool getInfoFromDwarfSection(pint_t pc, const UnwindInfoSections &sects,
461                                             uint32_t fdeSectionOffsetHint=0);
stepWithDwarfFDE()462   int stepWithDwarfFDE() {
463     return DwarfInstructions<A, R>::stepWithDwarf(_addressSpace,
464                                               (pint_t)this->getReg(UNW_REG_IP),
465                                               (pint_t)_info.unwind_info,
466                                               _registers);
467   }
468 #endif
469 
470 #if _LIBUNWIND_SUPPORT_COMPACT_UNWIND
471   bool getInfoFromCompactEncodingSection(pint_t pc,
472                                             const UnwindInfoSections &sects);
stepWithCompactEncoding()473   int stepWithCompactEncoding() {
474   #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
475     if ( compactSaysUseDwarf() )
476       return stepWithDwarfFDE();
477   #endif
478     R dummy;
479     return stepWithCompactEncoding(dummy);
480   }
481 
stepWithCompactEncoding(Registers_x86_64 &)482   int stepWithCompactEncoding(Registers_x86_64 &) {
483     return CompactUnwinder_x86_64<A>::stepWithCompactEncoding(
484         _info.format, _info.start_ip, _addressSpace, _registers);
485   }
486 
stepWithCompactEncoding(Registers_x86 &)487   int stepWithCompactEncoding(Registers_x86 &) {
488     return CompactUnwinder_x86<A>::stepWithCompactEncoding(
489         _info.format, (uint32_t)_info.start_ip, _addressSpace, _registers);
490   }
491 
stepWithCompactEncoding(Registers_ppc &)492   int stepWithCompactEncoding(Registers_ppc &) {
493     return UNW_EINVAL;
494   }
495 
stepWithCompactEncoding(Registers_arm64 &)496   int stepWithCompactEncoding(Registers_arm64 &) {
497     return CompactUnwinder_arm64<A>::stepWithCompactEncoding(
498         _info.format, _info.start_ip, _addressSpace, _registers);
499   }
500 
compactSaysUseDwarf(uint32_t * offset=NULL) const501   bool compactSaysUseDwarf(uint32_t *offset=NULL) const {
502     R dummy;
503     return compactSaysUseDwarf(dummy, offset);
504   }
505 
compactSaysUseDwarf(Registers_x86_64 &,uint32_t * offset) const506   bool compactSaysUseDwarf(Registers_x86_64 &, uint32_t *offset) const {
507     if ((_info.format & UNWIND_X86_64_MODE_MASK) == UNWIND_X86_64_MODE_DWARF) {
508       if (offset)
509         *offset = (_info.format & UNWIND_X86_64_DWARF_SECTION_OFFSET);
510       return true;
511     }
512     return false;
513   }
514 
compactSaysUseDwarf(Registers_x86 &,uint32_t * offset) const515   bool compactSaysUseDwarf(Registers_x86 &, uint32_t *offset) const {
516     if ((_info.format & UNWIND_X86_MODE_MASK) == UNWIND_X86_MODE_DWARF) {
517       if (offset)
518         *offset = (_info.format & UNWIND_X86_DWARF_SECTION_OFFSET);
519       return true;
520     }
521     return false;
522   }
523 
compactSaysUseDwarf(Registers_ppc &,uint32_t *) const524   bool compactSaysUseDwarf(Registers_ppc &, uint32_t *) const {
525     return true;
526   }
527 
compactSaysUseDwarf(Registers_arm64 &,uint32_t * offset) const528   bool compactSaysUseDwarf(Registers_arm64 &, uint32_t *offset) const {
529     if ((_info.format & UNWIND_ARM64_MODE_MASK) == UNWIND_ARM64_MODE_DWARF) {
530       if (offset)
531         *offset = (_info.format & UNWIND_ARM64_DWARF_SECTION_OFFSET);
532       return true;
533     }
534     return false;
535   }
536 #endif // _LIBUNWIND_SUPPORT_COMPACT_UNWIND
537 
538 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
dwarfEncoding() const539   compact_unwind_encoding_t dwarfEncoding() const {
540     R dummy;
541     return dwarfEncoding(dummy);
542   }
543 
dwarfEncoding(Registers_x86_64 &) const544   compact_unwind_encoding_t dwarfEncoding(Registers_x86_64 &) const {
545     return UNWIND_X86_64_MODE_DWARF;
546   }
547 
dwarfEncoding(Registers_x86 &) const548   compact_unwind_encoding_t dwarfEncoding(Registers_x86 &) const {
549     return UNWIND_X86_MODE_DWARF;
550   }
551 
dwarfEncoding(Registers_ppc &) const552   compact_unwind_encoding_t dwarfEncoding(Registers_ppc &) const {
553     return 0;
554   }
555 
dwarfEncoding(Registers_arm64 &) const556   compact_unwind_encoding_t dwarfEncoding(Registers_arm64 &) const {
557     return UNWIND_ARM64_MODE_DWARF;
558   }
559 #endif // _LIBUNWIND_SUPPORT_DWARF_UNWIND
560 
561 
562   A               &_addressSpace;
563   R                _registers;
564   unw_proc_info_t  _info;
565   bool             _unwindInfoMissing;
566   bool             _isSignalFrame;
567 };
568 
569 
570 template <typename A, typename R>
UnwindCursor(unw_context_t * context,A & as)571 UnwindCursor<A, R>::UnwindCursor(unw_context_t *context, A &as)
572     : _addressSpace(as), _registers(context), _unwindInfoMissing(false),
573       _isSignalFrame(false) {
574   static_assert(sizeof(UnwindCursor<A, R>) < sizeof(unw_cursor_t),
575                 "UnwindCursor<> does not fit in unw_cursor_t");
576   memset(&_info, 0, sizeof(_info));
577 }
578 
579 template <typename A, typename R>
UnwindCursor(A & as,void *)580 UnwindCursor<A, R>::UnwindCursor(A &as, void *)
581     : _addressSpace(as), _unwindInfoMissing(false), _isSignalFrame(false) {
582   memset(&_info, 0, sizeof(_info));
583   // FIXME
584   // fill in _registers from thread arg
585 }
586 
587 
588 template <typename A, typename R>
validReg(int regNum)589 bool UnwindCursor<A, R>::validReg(int regNum) {
590   return _registers.validRegister(regNum);
591 }
592 
593 template <typename A, typename R>
getReg(int regNum)594 unw_word_t UnwindCursor<A, R>::getReg(int regNum) {
595   return _registers.getRegister(regNum);
596 }
597 
598 template <typename A, typename R>
setReg(int regNum,unw_word_t value)599 void UnwindCursor<A, R>::setReg(int regNum, unw_word_t value) {
600   _registers.setRegister(regNum, (typename A::pint_t)value);
601 }
602 
603 template <typename A, typename R>
validFloatReg(int regNum)604 bool UnwindCursor<A, R>::validFloatReg(int regNum) {
605   return _registers.validFloatRegister(regNum);
606 }
607 
608 template <typename A, typename R>
getFloatReg(int regNum)609 unw_fpreg_t UnwindCursor<A, R>::getFloatReg(int regNum) {
610   return _registers.getFloatRegister(regNum);
611 }
612 
613 template <typename A, typename R>
setFloatReg(int regNum,unw_fpreg_t value)614 void UnwindCursor<A, R>::setFloatReg(int regNum, unw_fpreg_t value) {
615   _registers.setFloatRegister(regNum, value);
616 }
617 
jumpto()618 template <typename A, typename R> void UnwindCursor<A, R>::jumpto() {
619   _registers.jumpto();
620 }
621 
622 #ifdef __arm__
saveVFPAsX()623 template <typename A, typename R> void UnwindCursor<A, R>::saveVFPAsX() {
624   _registers.saveVFPAsX();
625 }
626 #endif
627 
628 template <typename A, typename R>
getRegisterName(int regNum)629 const char *UnwindCursor<A, R>::getRegisterName(int regNum) {
630   return _registers.getRegisterName(regNum);
631 }
632 
isSignalFrame()633 template <typename A, typename R> bool UnwindCursor<A, R>::isSignalFrame() {
634   return _isSignalFrame;
635 }
636 
637 #if _LIBUNWIND_ARM_EHABI
638 struct EHABIIndexEntry {
639   uint32_t functionOffset;
640   uint32_t data;
641 };
642 
643 template<typename A>
644 struct EHABISectionIterator {
645   typedef EHABISectionIterator _Self;
646 
647   typedef std::random_access_iterator_tag iterator_category;
648   typedef typename A::pint_t value_type;
649   typedef typename A::pint_t* pointer;
650   typedef typename A::pint_t& reference;
651   typedef size_t size_type;
652   typedef size_t difference_type;
653 
beginlibunwind::EHABISectionIterator654   static _Self begin(A& addressSpace, const UnwindInfoSections& sects) {
655     return _Self(addressSpace, sects, 0);
656   }
endlibunwind::EHABISectionIterator657   static _Self end(A& addressSpace, const UnwindInfoSections& sects) {
658     return _Self(addressSpace, sects, sects.arm_section_length);
659   }
660 
EHABISectionIteratorlibunwind::EHABISectionIterator661   EHABISectionIterator(A& addressSpace, const UnwindInfoSections& sects, size_t i)
662       : _i(i), _addressSpace(&addressSpace), _sects(&sects) {}
663 
operator ++libunwind::EHABISectionIterator664   _Self& operator++() { ++_i; return *this; }
operator +=libunwind::EHABISectionIterator665   _Self& operator+=(size_t a) { _i += a; return *this; }
operator --libunwind::EHABISectionIterator666   _Self& operator--() { assert(_i > 0); --_i; return *this; }
operator -=libunwind::EHABISectionIterator667   _Self& operator-=(size_t a) { assert(_i >= a); _i -= a; return *this; }
668 
operator +libunwind::EHABISectionIterator669   _Self operator+(size_t a) { _Self out = *this; out._i += a; return out; }
operator -libunwind::EHABISectionIterator670   _Self operator-(size_t a) { assert(_i >= a); _Self out = *this; out._i -= a; return out; }
671 
operator -libunwind::EHABISectionIterator672   size_t operator-(const _Self& other) { return _i - other._i; }
673 
operator ==libunwind::EHABISectionIterator674   bool operator==(const _Self& other) const {
675     assert(_addressSpace == other._addressSpace);
676     assert(_sects == other._sects);
677     return _i == other._i;
678   }
679 
operator *libunwind::EHABISectionIterator680   typename A::pint_t operator*() const { return functionAddress(); }
681 
functionAddresslibunwind::EHABISectionIterator682   typename A::pint_t functionAddress() const {
683     typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
684         EHABIIndexEntry, _i, functionOffset);
685     return indexAddr + signExtendPrel31(_addressSpace->get32(indexAddr));
686   }
687 
dataAddresslibunwind::EHABISectionIterator688   typename A::pint_t dataAddress() {
689     typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
690         EHABIIndexEntry, _i, data);
691     return indexAddr;
692   }
693 
694  private:
695   size_t _i;
696   A* _addressSpace;
697   const UnwindInfoSections* _sects;
698 };
699 
700 template <typename A, typename R>
getInfoFromEHABISection(pint_t pc,const UnwindInfoSections & sects)701 bool UnwindCursor<A, R>::getInfoFromEHABISection(
702     pint_t pc,
703     const UnwindInfoSections &sects) {
704   EHABISectionIterator<A> begin =
705       EHABISectionIterator<A>::begin(_addressSpace, sects);
706   EHABISectionIterator<A> end =
707       EHABISectionIterator<A>::end(_addressSpace, sects);
708 
709   EHABISectionIterator<A> itNextPC = std::upper_bound(begin, end, pc);
710   if (itNextPC == begin || itNextPC == end)
711     return false;
712   EHABISectionIterator<A> itThisPC = itNextPC - 1;
713 
714   pint_t thisPC = itThisPC.functionAddress();
715   pint_t nextPC = itNextPC.functionAddress();
716   pint_t indexDataAddr = itThisPC.dataAddress();
717 
718   if (indexDataAddr == 0)
719     return false;
720 
721   uint32_t indexData = _addressSpace.get32(indexDataAddr);
722   if (indexData == UNW_EXIDX_CANTUNWIND)
723     return false;
724 
725   // If the high bit is set, the exception handling table entry is inline inside
726   // the index table entry on the second word (aka |indexDataAddr|). Otherwise,
727   // the table points at an offset in the exception handling table (section 5 EHABI).
728   pint_t exceptionTableAddr;
729   uint32_t exceptionTableData;
730   bool isSingleWordEHT;
731   if (indexData & 0x80000000) {
732     exceptionTableAddr = indexDataAddr;
733     // TODO(ajwong): Should this data be 0?
734     exceptionTableData = indexData;
735     isSingleWordEHT = true;
736   } else {
737     exceptionTableAddr = indexDataAddr + signExtendPrel31(indexData);
738     exceptionTableData = _addressSpace.get32(exceptionTableAddr);
739     isSingleWordEHT = false;
740   }
741 
742   // Now we know the 3 things:
743   //   exceptionTableAddr -- exception handler table entry.
744   //   exceptionTableData -- the data inside the first word of the eht entry.
745   //   isSingleWordEHT -- whether the entry is in the index.
746   unw_word_t personalityRoutine = 0xbadf00d;
747   bool scope32 = false;
748   uintptr_t lsda;
749 
750   // If the high bit in the exception handling table entry is set, the entry is
751   // in compact form (section 6.3 EHABI).
752   if (exceptionTableData & 0x80000000) {
753     // Grab the index of the personality routine from the compact form.
754     uint32_t choice = (exceptionTableData & 0x0f000000) >> 24;
755     uint32_t extraWords = 0;
756     switch (choice) {
757       case 0:
758         personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr0;
759         extraWords = 0;
760         scope32 = false;
761         lsda = isSingleWordEHT ? 0 : (exceptionTableAddr + 4);
762         break;
763       case 1:
764         personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr1;
765         extraWords = (exceptionTableData & 0x00ff0000) >> 16;
766         scope32 = false;
767         lsda = exceptionTableAddr + (extraWords + 1) * 4;
768         break;
769       case 2:
770         personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr2;
771         extraWords = (exceptionTableData & 0x00ff0000) >> 16;
772         scope32 = true;
773         lsda = exceptionTableAddr + (extraWords + 1) * 4;
774         break;
775       default:
776         _LIBUNWIND_ABORT("unknown personality routine");
777         return false;
778     }
779 
780     if (isSingleWordEHT) {
781       if (extraWords != 0) {
782         _LIBUNWIND_ABORT("index inlined table detected but pr function "
783                          "requires extra words");
784         return false;
785       }
786     }
787   } else {
788     pint_t personalityAddr =
789         exceptionTableAddr + signExtendPrel31(exceptionTableData);
790     personalityRoutine = personalityAddr;
791 
792     // ARM EHABI # 6.2, # 9.2
793     //
794     //  +---- ehtp
795     //  v
796     // +--------------------------------------+
797     // | +--------+--------+--------+-------+ |
798     // | |0| prel31 to personalityRoutine   | |
799     // | +--------+--------+--------+-------+ |
800     // | |      N |      unwind opcodes     | |  <-- UnwindData
801     // | +--------+--------+--------+-------+ |
802     // | | Word 2        unwind opcodes     | |
803     // | +--------+--------+--------+-------+ |
804     // | ...                                  |
805     // | +--------+--------+--------+-------+ |
806     // | | Word N        unwind opcodes     | |
807     // | +--------+--------+--------+-------+ |
808     // | | LSDA                             | |  <-- lsda
809     // | | ...                              | |
810     // | +--------+--------+--------+-------+ |
811     // +--------------------------------------+
812 
813     uint32_t *UnwindData = reinterpret_cast<uint32_t*>(exceptionTableAddr) + 1;
814     uint32_t FirstDataWord = *UnwindData;
815     size_t N = ((FirstDataWord >> 24) & 0xff);
816     size_t NDataWords = N + 1;
817     lsda = reinterpret_cast<uintptr_t>(UnwindData + NDataWords);
818   }
819 
820   _info.start_ip = thisPC;
821   _info.end_ip = nextPC;
822   _info.handler = personalityRoutine;
823   _info.unwind_info = exceptionTableAddr;
824   _info.lsda = lsda;
825   // flags is pr_cache.additional. See EHABI #7.2 for definition of bit 0.
826   _info.flags = isSingleWordEHT ? 1 : 0 | scope32 ? 0x2 : 0;  // Use enum?
827 
828   return true;
829 }
830 #endif
831 
832 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
833 template <typename A, typename R>
getInfoFromDwarfSection(pint_t pc,const UnwindInfoSections & sects,uint32_t fdeSectionOffsetHint)834 bool UnwindCursor<A, R>::getInfoFromDwarfSection(pint_t pc,
835                                                 const UnwindInfoSections &sects,
836                                                 uint32_t fdeSectionOffsetHint) {
837   typename CFI_Parser<A>::FDE_Info fdeInfo;
838   typename CFI_Parser<A>::CIE_Info cieInfo;
839   bool foundFDE = false;
840   bool foundInCache = false;
841   // If compact encoding table gave offset into dwarf section, go directly there
842   if (fdeSectionOffsetHint != 0) {
843     foundFDE = CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
844                                     (uint32_t)sects.dwarf_section_length,
845                                     sects.dwarf_section + fdeSectionOffsetHint,
846                                     &fdeInfo, &cieInfo);
847   }
848 #if _LIBUNWIND_SUPPORT_DWARF_INDEX
849   if (!foundFDE && (sects.dwarf_index_section != 0)) {
850     foundFDE = EHHeaderParser<A>::findFDE(
851         _addressSpace, pc, sects.dwarf_index_section,
852         (uint32_t)sects.dwarf_index_section_length, &fdeInfo, &cieInfo);
853   }
854 #endif
855   if (!foundFDE) {
856     // otherwise, search cache of previously found FDEs.
857     pint_t cachedFDE = DwarfFDECache<A>::findFDE(sects.dso_base, pc);
858     if (cachedFDE != 0) {
859       foundFDE =
860           CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
861                                  (uint32_t)sects.dwarf_section_length,
862                                  cachedFDE, &fdeInfo, &cieInfo);
863       foundInCache = foundFDE;
864     }
865   }
866   if (!foundFDE) {
867     // Still not found, do full scan of __eh_frame section.
868     foundFDE = CFI_Parser<A>::findFDE(_addressSpace, pc, sects.dwarf_section,
869                                       (uint32_t)sects.dwarf_section_length, 0,
870                                       &fdeInfo, &cieInfo);
871   }
872   if (foundFDE) {
873     typename CFI_Parser<A>::PrologInfo prolog;
874     if (CFI_Parser<A>::parseFDEInstructions(_addressSpace, fdeInfo, cieInfo, pc,
875                                             &prolog)) {
876       // Save off parsed FDE info
877       _info.start_ip          = fdeInfo.pcStart;
878       _info.end_ip            = fdeInfo.pcEnd;
879       _info.lsda              = fdeInfo.lsda;
880       _info.handler           = cieInfo.personality;
881       _info.gp                = prolog.spExtraArgSize;
882       _info.flags             = 0;
883       _info.format            = dwarfEncoding();
884       _info.unwind_info       = fdeInfo.fdeStart;
885       _info.unwind_info_size  = (uint32_t)fdeInfo.fdeLength;
886       _info.extra             = (unw_word_t) sects.dso_base;
887 
888       // Add to cache (to make next lookup faster) if we had no hint
889       // and there was no index.
890       if (!foundInCache && (fdeSectionOffsetHint == 0)) {
891   #if _LIBUNWIND_SUPPORT_DWARF_INDEX
892         if (sects.dwarf_index_section == 0)
893   #endif
894         DwarfFDECache<A>::add(sects.dso_base, fdeInfo.pcStart, fdeInfo.pcEnd,
895                               fdeInfo.fdeStart);
896       }
897       return true;
898     }
899   }
900   //_LIBUNWIND_DEBUG_LOG("can't find/use FDE for pc=0x%llX\n", (uint64_t)pc);
901   return false;
902 }
903 #endif // _LIBUNWIND_SUPPORT_DWARF_UNWIND
904 
905 
906 #if _LIBUNWIND_SUPPORT_COMPACT_UNWIND
907 template <typename A, typename R>
getInfoFromCompactEncodingSection(pint_t pc,const UnwindInfoSections & sects)908 bool UnwindCursor<A, R>::getInfoFromCompactEncodingSection(pint_t pc,
909                                               const UnwindInfoSections &sects) {
910   const bool log = false;
911   if (log)
912     fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX, mh=0x%llX)\n",
913             (uint64_t)pc, (uint64_t)sects.dso_base);
914 
915   const UnwindSectionHeader<A> sectionHeader(_addressSpace,
916                                                 sects.compact_unwind_section);
917   if (sectionHeader.version() != UNWIND_SECTION_VERSION)
918     return false;
919 
920   // do a binary search of top level index to find page with unwind info
921   pint_t targetFunctionOffset = pc - sects.dso_base;
922   const UnwindSectionIndexArray<A> topIndex(_addressSpace,
923                                            sects.compact_unwind_section
924                                          + sectionHeader.indexSectionOffset());
925   uint32_t low = 0;
926   uint32_t high = sectionHeader.indexCount();
927   uint32_t last = high - 1;
928   while (low < high) {
929     uint32_t mid = (low + high) / 2;
930     //if ( log ) fprintf(stderr, "\tmid=%d, low=%d, high=%d, *mid=0x%08X\n",
931     //mid, low, high, topIndex.functionOffset(mid));
932     if (topIndex.functionOffset(mid) <= targetFunctionOffset) {
933       if ((mid == last) ||
934           (topIndex.functionOffset(mid + 1) > targetFunctionOffset)) {
935         low = mid;
936         break;
937       } else {
938         low = mid + 1;
939       }
940     } else {
941       high = mid;
942     }
943   }
944   const uint32_t firstLevelFunctionOffset = topIndex.functionOffset(low);
945   const uint32_t firstLevelNextPageFunctionOffset =
946       topIndex.functionOffset(low + 1);
947   const pint_t secondLevelAddr =
948       sects.compact_unwind_section + topIndex.secondLevelPagesSectionOffset(low);
949   const pint_t lsdaArrayStartAddr =
950       sects.compact_unwind_section + topIndex.lsdaIndexArraySectionOffset(low);
951   const pint_t lsdaArrayEndAddr =
952       sects.compact_unwind_section + topIndex.lsdaIndexArraySectionOffset(low+1);
953   if (log)
954     fprintf(stderr, "\tfirst level search for result index=%d "
955                     "to secondLevelAddr=0x%llX\n",
956                     low, (uint64_t) secondLevelAddr);
957   // do a binary search of second level page index
958   uint32_t encoding = 0;
959   pint_t funcStart = 0;
960   pint_t funcEnd = 0;
961   pint_t lsda = 0;
962   pint_t personality = 0;
963   uint32_t pageKind = _addressSpace.get32(secondLevelAddr);
964   if (pageKind == UNWIND_SECOND_LEVEL_REGULAR) {
965     // regular page
966     UnwindSectionRegularPageHeader<A> pageHeader(_addressSpace,
967                                                  secondLevelAddr);
968     UnwindSectionRegularArray<A> pageIndex(
969         _addressSpace, secondLevelAddr + pageHeader.entryPageOffset());
970     // binary search looks for entry with e where index[e].offset <= pc <
971     // index[e+1].offset
972     if (log)
973       fprintf(stderr, "\tbinary search for targetFunctionOffset=0x%08llX in "
974                       "regular page starting at secondLevelAddr=0x%llX\n",
975               (uint64_t) targetFunctionOffset, (uint64_t) secondLevelAddr);
976     low = 0;
977     high = pageHeader.entryCount();
978     while (low < high) {
979       uint32_t mid = (low + high) / 2;
980       if (pageIndex.functionOffset(mid) <= targetFunctionOffset) {
981         if (mid == (uint32_t)(pageHeader.entryCount() - 1)) {
982           // at end of table
983           low = mid;
984           funcEnd = firstLevelNextPageFunctionOffset + sects.dso_base;
985           break;
986         } else if (pageIndex.functionOffset(mid + 1) > targetFunctionOffset) {
987           // next is too big, so we found it
988           low = mid;
989           funcEnd = pageIndex.functionOffset(low + 1) + sects.dso_base;
990           break;
991         } else {
992           low = mid + 1;
993         }
994       } else {
995         high = mid;
996       }
997     }
998     encoding = pageIndex.encoding(low);
999     funcStart = pageIndex.functionOffset(low) + sects.dso_base;
1000     if (pc < funcStart) {
1001       if (log)
1002         fprintf(
1003             stderr,
1004             "\tpc not in table, pc=0x%llX, funcStart=0x%llX, funcEnd=0x%llX\n",
1005             (uint64_t) pc, (uint64_t) funcStart, (uint64_t) funcEnd);
1006       return false;
1007     }
1008     if (pc > funcEnd) {
1009       if (log)
1010         fprintf(
1011             stderr,
1012             "\tpc not in table, pc=0x%llX, funcStart=0x%llX, funcEnd=0x%llX\n",
1013             (uint64_t) pc, (uint64_t) funcStart, (uint64_t) funcEnd);
1014       return false;
1015     }
1016   } else if (pageKind == UNWIND_SECOND_LEVEL_COMPRESSED) {
1017     // compressed page
1018     UnwindSectionCompressedPageHeader<A> pageHeader(_addressSpace,
1019                                                     secondLevelAddr);
1020     UnwindSectionCompressedArray<A> pageIndex(
1021         _addressSpace, secondLevelAddr + pageHeader.entryPageOffset());
1022     const uint32_t targetFunctionPageOffset =
1023         (uint32_t)(targetFunctionOffset - firstLevelFunctionOffset);
1024     // binary search looks for entry with e where index[e].offset <= pc <
1025     // index[e+1].offset
1026     if (log)
1027       fprintf(stderr, "\tbinary search of compressed page starting at "
1028                       "secondLevelAddr=0x%llX\n",
1029               (uint64_t) secondLevelAddr);
1030     low = 0;
1031     last = pageHeader.entryCount() - 1;
1032     high = pageHeader.entryCount();
1033     while (low < high) {
1034       uint32_t mid = (low + high) / 2;
1035       if (pageIndex.functionOffset(mid) <= targetFunctionPageOffset) {
1036         if ((mid == last) ||
1037             (pageIndex.functionOffset(mid + 1) > targetFunctionPageOffset)) {
1038           low = mid;
1039           break;
1040         } else {
1041           low = mid + 1;
1042         }
1043       } else {
1044         high = mid;
1045       }
1046     }
1047     funcStart = pageIndex.functionOffset(low) + firstLevelFunctionOffset
1048                                                               + sects.dso_base;
1049     if (low < last)
1050       funcEnd =
1051           pageIndex.functionOffset(low + 1) + firstLevelFunctionOffset
1052                                                               + sects.dso_base;
1053     else
1054       funcEnd = firstLevelNextPageFunctionOffset + sects.dso_base;
1055     if (pc < funcStart) {
1056       _LIBUNWIND_DEBUG_LOG("malformed __unwind_info, pc=0x%llX not in second  "
1057                            "level compressed unwind table. funcStart=0x%llX\n",
1058                             (uint64_t) pc, (uint64_t) funcStart);
1059       return false;
1060     }
1061     if (pc > funcEnd) {
1062       _LIBUNWIND_DEBUG_LOG("malformed __unwind_info, pc=0x%llX not in second  "
1063                           "level compressed unwind table. funcEnd=0x%llX\n",
1064                            (uint64_t) pc, (uint64_t) funcEnd);
1065       return false;
1066     }
1067     uint16_t encodingIndex = pageIndex.encodingIndex(low);
1068     if (encodingIndex < sectionHeader.commonEncodingsArrayCount()) {
1069       // encoding is in common table in section header
1070       encoding = _addressSpace.get32(
1071           sects.compact_unwind_section +
1072           sectionHeader.commonEncodingsArraySectionOffset() +
1073           encodingIndex * sizeof(uint32_t));
1074     } else {
1075       // encoding is in page specific table
1076       uint16_t pageEncodingIndex =
1077           encodingIndex - (uint16_t)sectionHeader.commonEncodingsArrayCount();
1078       encoding = _addressSpace.get32(secondLevelAddr +
1079                                      pageHeader.encodingsPageOffset() +
1080                                      pageEncodingIndex * sizeof(uint32_t));
1081     }
1082   } else {
1083     _LIBUNWIND_DEBUG_LOG("malformed __unwind_info at 0x%0llX bad second "
1084                          "level page\n",
1085                           (uint64_t) sects.compact_unwind_section);
1086     return false;
1087   }
1088 
1089   // look up LSDA, if encoding says function has one
1090   if (encoding & UNWIND_HAS_LSDA) {
1091     UnwindSectionLsdaArray<A> lsdaIndex(_addressSpace, lsdaArrayStartAddr);
1092     uint32_t funcStartOffset = (uint32_t)(funcStart - sects.dso_base);
1093     low = 0;
1094     high = (uint32_t)(lsdaArrayEndAddr - lsdaArrayStartAddr) /
1095                     sizeof(unwind_info_section_header_lsda_index_entry);
1096     // binary search looks for entry with exact match for functionOffset
1097     if (log)
1098       fprintf(stderr,
1099               "\tbinary search of lsda table for targetFunctionOffset=0x%08X\n",
1100               funcStartOffset);
1101     while (low < high) {
1102       uint32_t mid = (low + high) / 2;
1103       if (lsdaIndex.functionOffset(mid) == funcStartOffset) {
1104         lsda = lsdaIndex.lsdaOffset(mid) + sects.dso_base;
1105         break;
1106       } else if (lsdaIndex.functionOffset(mid) < funcStartOffset) {
1107         low = mid + 1;
1108       } else {
1109         high = mid;
1110       }
1111     }
1112     if (lsda == 0) {
1113       _LIBUNWIND_DEBUG_LOG("found encoding 0x%08X with HAS_LSDA bit set for "
1114                     "pc=0x%0llX, but lsda table has no entry\n",
1115                     encoding, (uint64_t) pc);
1116       return false;
1117     }
1118   }
1119 
1120   // extact personality routine, if encoding says function has one
1121   uint32_t personalityIndex = (encoding & UNWIND_PERSONALITY_MASK) >>
1122                               (__builtin_ctz(UNWIND_PERSONALITY_MASK));
1123   if (personalityIndex != 0) {
1124     --personalityIndex; // change 1-based to zero-based index
1125     if (personalityIndex > sectionHeader.personalityArrayCount()) {
1126       _LIBUNWIND_DEBUG_LOG("found encoding 0x%08X with personality index %d,  "
1127                             "but personality table has only %d entires\n",
1128                             encoding, personalityIndex,
1129                             sectionHeader.personalityArrayCount());
1130       return false;
1131     }
1132     int32_t personalityDelta = (int32_t)_addressSpace.get32(
1133         sects.compact_unwind_section +
1134         sectionHeader.personalityArraySectionOffset() +
1135         personalityIndex * sizeof(uint32_t));
1136     pint_t personalityPointer = sects.dso_base + (pint_t)personalityDelta;
1137     personality = _addressSpace.getP(personalityPointer);
1138     if (log)
1139       fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX), "
1140                       "personalityDelta=0x%08X, personality=0x%08llX\n",
1141               (uint64_t) pc, personalityDelta, (uint64_t) personality);
1142   }
1143 
1144   if (log)
1145     fprintf(stderr, "getInfoFromCompactEncodingSection(pc=0x%llX), "
1146                     "encoding=0x%08X, lsda=0x%08llX for funcStart=0x%llX\n",
1147             (uint64_t) pc, encoding, (uint64_t) lsda, (uint64_t) funcStart);
1148   _info.start_ip = funcStart;
1149   _info.end_ip = funcEnd;
1150   _info.lsda = lsda;
1151   _info.handler = personality;
1152   _info.gp = 0;
1153   _info.flags = 0;
1154   _info.format = encoding;
1155   _info.unwind_info = 0;
1156   _info.unwind_info_size = 0;
1157   _info.extra = sects.dso_base;
1158   return true;
1159 }
1160 #endif // _LIBUNWIND_SUPPORT_COMPACT_UNWIND
1161 
1162 
1163 template <typename A, typename R>
setInfoBasedOnIPRegister(bool isReturnAddress)1164 void UnwindCursor<A, R>::setInfoBasedOnIPRegister(bool isReturnAddress) {
1165   pint_t pc = (pint_t)this->getReg(UNW_REG_IP);
1166 #if _LIBUNWIND_ARM_EHABI
1167   // Remove the thumb bit so the IP represents the actual instruction address.
1168   // This matches the behaviour of _Unwind_GetIP on arm.
1169   pc &= (pint_t)~0x1;
1170 #endif
1171 
1172   // If the last line of a function is a "throw" the compiler sometimes
1173   // emits no instructions after the call to __cxa_throw.  This means
1174   // the return address is actually the start of the next function.
1175   // To disambiguate this, back up the pc when we know it is a return
1176   // address.
1177   if (isReturnAddress)
1178     --pc;
1179 
1180   // Ask address space object to find unwind sections for this pc.
1181   UnwindInfoSections sects;
1182   if (_addressSpace.findUnwindSections(pc, sects)) {
1183 #if _LIBUNWIND_SUPPORT_COMPACT_UNWIND
1184     // If there is a compact unwind encoding table, look there first.
1185     if (sects.compact_unwind_section != 0) {
1186       if (this->getInfoFromCompactEncodingSection(pc, sects)) {
1187   #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
1188         // Found info in table, done unless encoding says to use dwarf.
1189         uint32_t dwarfOffset;
1190         if ((sects.dwarf_section != 0) && compactSaysUseDwarf(&dwarfOffset)) {
1191           if (this->getInfoFromDwarfSection(pc, sects, dwarfOffset)) {
1192             // found info in dwarf, done
1193             return;
1194           }
1195         }
1196   #endif
1197         // If unwind table has entry, but entry says there is no unwind info,
1198         // record that we have no unwind info.
1199         if (_info.format == 0)
1200           _unwindInfoMissing = true;
1201         return;
1202       }
1203     }
1204 #endif // _LIBUNWIND_SUPPORT_COMPACT_UNWIND
1205 
1206 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
1207     // If there is dwarf unwind info, look there next.
1208     if (sects.dwarf_section != 0) {
1209       if (this->getInfoFromDwarfSection(pc, sects)) {
1210         // found info in dwarf, done
1211         return;
1212       }
1213     }
1214 #endif
1215 
1216 #if _LIBUNWIND_ARM_EHABI
1217     // If there is ARM EHABI unwind info, look there next.
1218     if (sects.arm_section != 0 && this->getInfoFromEHABISection(pc, sects))
1219       return;
1220 #endif
1221   }
1222 
1223 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
1224   // There is no static unwind info for this pc. Look to see if an FDE was
1225   // dynamically registered for it.
1226   pint_t cachedFDE = DwarfFDECache<A>::findFDE(0, pc);
1227   if (cachedFDE != 0) {
1228     CFI_Parser<LocalAddressSpace>::FDE_Info fdeInfo;
1229     CFI_Parser<LocalAddressSpace>::CIE_Info cieInfo;
1230     const char *msg = CFI_Parser<A>::decodeFDE(_addressSpace,
1231                                                 cachedFDE, &fdeInfo, &cieInfo);
1232     if (msg == NULL) {
1233       typename CFI_Parser<A>::PrologInfo prolog;
1234       if (CFI_Parser<A>::parseFDEInstructions(_addressSpace, fdeInfo, cieInfo,
1235                                                                 pc, &prolog)) {
1236         // save off parsed FDE info
1237         _info.start_ip         = fdeInfo.pcStart;
1238         _info.end_ip           = fdeInfo.pcEnd;
1239         _info.lsda             = fdeInfo.lsda;
1240         _info.handler          = cieInfo.personality;
1241         _info.gp               = prolog.spExtraArgSize;
1242                                   // Some frameless functions need SP
1243                                   // altered when resuming in function.
1244         _info.flags            = 0;
1245         _info.format           = dwarfEncoding();
1246         _info.unwind_info      = fdeInfo.fdeStart;
1247         _info.unwind_info_size = (uint32_t)fdeInfo.fdeLength;
1248         _info.extra            = 0;
1249         return;
1250       }
1251     }
1252   }
1253 
1254   // Lastly, ask AddressSpace object about platform specific ways to locate
1255   // other FDEs.
1256   pint_t fde;
1257   if (_addressSpace.findOtherFDE(pc, fde)) {
1258     CFI_Parser<LocalAddressSpace>::FDE_Info fdeInfo;
1259     CFI_Parser<LocalAddressSpace>::CIE_Info cieInfo;
1260     if (!CFI_Parser<A>::decodeFDE(_addressSpace, fde, &fdeInfo, &cieInfo)) {
1261       // Double check this FDE is for a function that includes the pc.
1262       if ((fdeInfo.pcStart <= pc) && (pc < fdeInfo.pcEnd)) {
1263         typename CFI_Parser<A>::PrologInfo prolog;
1264         if (CFI_Parser<A>::parseFDEInstructions(_addressSpace, fdeInfo,
1265                                                 cieInfo, pc, &prolog)) {
1266           // save off parsed FDE info
1267           _info.start_ip         = fdeInfo.pcStart;
1268           _info.end_ip           = fdeInfo.pcEnd;
1269           _info.lsda             = fdeInfo.lsda;
1270           _info.handler          = cieInfo.personality;
1271           _info.gp               = prolog.spExtraArgSize;
1272           _info.flags            = 0;
1273           _info.format           = dwarfEncoding();
1274           _info.unwind_info      = fdeInfo.fdeStart;
1275           _info.unwind_info_size = (uint32_t)fdeInfo.fdeLength;
1276           _info.extra            = 0;
1277           return;
1278         }
1279       }
1280     }
1281   }
1282 #endif // #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
1283 
1284   // no unwind info, flag that we can't reliably unwind
1285   _unwindInfoMissing = true;
1286 }
1287 
1288 template <typename A, typename R>
step()1289 int UnwindCursor<A, R>::step() {
1290   // Bottom of stack is defined is when unwind info cannot be found.
1291   if (_unwindInfoMissing)
1292     return UNW_STEP_END;
1293 
1294   // Use unwinding info to modify register set as if function returned.
1295   int result;
1296 #if _LIBUNWIND_SUPPORT_COMPACT_UNWIND
1297   result = this->stepWithCompactEncoding();
1298 #elif _LIBUNWIND_SUPPORT_DWARF_UNWIND
1299   result = this->stepWithDwarfFDE();
1300 #elif _LIBUNWIND_ARM_EHABI
1301   result = this->stepWithEHABI();
1302 #else
1303   #error Need _LIBUNWIND_SUPPORT_COMPACT_UNWIND or \
1304               _LIBUNWIND_SUPPORT_DWARF_UNWIND or \
1305               _LIBUNWIND_ARM_EHABI
1306 #endif
1307 
1308   // update info based on new PC
1309   if (result == UNW_STEP_SUCCESS) {
1310     this->setInfoBasedOnIPRegister(true);
1311     if (_unwindInfoMissing)
1312       return UNW_STEP_END;
1313     if (_info.gp)
1314       setReg(UNW_REG_SP, getReg(UNW_REG_SP) + _info.gp);
1315   }
1316 
1317   return result;
1318 }
1319 
1320 template <typename A, typename R>
getInfo(unw_proc_info_t * info)1321 void UnwindCursor<A, R>::getInfo(unw_proc_info_t *info) {
1322   *info = _info;
1323 }
1324 
1325 template <typename A, typename R>
getFunctionName(char * buf,size_t bufLen,unw_word_t * offset)1326 bool UnwindCursor<A, R>::getFunctionName(char *buf, size_t bufLen,
1327                                                            unw_word_t *offset) {
1328   return _addressSpace.findFunctionName((pint_t)this->getReg(UNW_REG_IP),
1329                                          buf, bufLen, offset);
1330 }
1331 
1332 } // namespace libunwind
1333 
1334 #endif // __UNWINDCURSOR_HPP__
1335