1 //===- DWARFDebugLoc.cpp --------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "llvm/DebugInfo/DWARF/DWARFDebugLoc.h"
10 #include "llvm/ADT/StringRef.h"
11 #include "llvm/BinaryFormat/Dwarf.h"
12 #include "llvm/DebugInfo/DIContext.h"
13 #include "llvm/DebugInfo/DWARF/DWARFAddressRange.h"
14 #include "llvm/DebugInfo/DWARF/DWARFExpression.h"
15 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
16 #include "llvm/DebugInfo/DWARF/DWARFLocationExpression.h"
17 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
18 #include "llvm/Support/Format.h"
19 #include "llvm/Support/raw_ostream.h"
20 #include <algorithm>
21 #include <cinttypes>
22 #include <cstdint>
23 
24 using namespace llvm;
25 using object::SectionedAddress;
26 
27 namespace llvm {
28 class DWARFObject;
29 }
30 
31 namespace {
32 class DWARFLocationInterpreter {
33   Optional<object::SectionedAddress> Base;
34   std::function<Optional<object::SectionedAddress>(uint32_t)> LookupAddr;
35 
36 public:
DWARFLocationInterpreter(Optional<object::SectionedAddress> Base,std::function<Optional<object::SectionedAddress> (uint32_t)> LookupAddr)37   DWARFLocationInterpreter(
38       Optional<object::SectionedAddress> Base,
39       std::function<Optional<object::SectionedAddress>(uint32_t)> LookupAddr)
40       : Base(Base), LookupAddr(std::move(LookupAddr)) {}
41 
42   Expected<Optional<DWARFLocationExpression>>
43   Interpret(const DWARFLocationEntry &E);
44 };
45 } // namespace
46 
createResolverError(uint32_t Index,unsigned Kind)47 static Error createResolverError(uint32_t Index, unsigned Kind) {
48   return make_error<ResolverError>(Index, (dwarf::LoclistEntries)Kind);
49 }
50 
51 Expected<Optional<DWARFLocationExpression>>
Interpret(const DWARFLocationEntry & E)52 DWARFLocationInterpreter::Interpret(const DWARFLocationEntry &E) {
53   switch (E.Kind) {
54   case dwarf::DW_LLE_end_of_list:
55     return None;
56   case dwarf::DW_LLE_base_addressx: {
57     Base = LookupAddr(E.Value0);
58     if (!Base)
59       return createResolverError(E.Value0, E.Kind);
60     return None;
61   }
62   case dwarf::DW_LLE_startx_endx: {
63     Optional<SectionedAddress> LowPC = LookupAddr(E.Value0);
64     if (!LowPC)
65       return createResolverError(E.Value0, E.Kind);
66     Optional<SectionedAddress> HighPC = LookupAddr(E.Value1);
67     if (!HighPC)
68       return createResolverError(E.Value1, E.Kind);
69     return DWARFLocationExpression{
70         DWARFAddressRange{LowPC->Address, HighPC->Address, LowPC->SectionIndex},
71         E.Loc};
72   }
73   case dwarf::DW_LLE_startx_length: {
74     Optional<SectionedAddress> LowPC = LookupAddr(E.Value0);
75     if (!LowPC)
76       return createResolverError(E.Value0, E.Kind);
77     return DWARFLocationExpression{DWARFAddressRange{LowPC->Address,
78                                                      LowPC->Address + E.Value1,
79                                                      LowPC->SectionIndex},
80                                    E.Loc};
81   }
82   case dwarf::DW_LLE_offset_pair: {
83     if (!Base) {
84       return createStringError(inconvertibleErrorCode(),
85                                "Unable to resolve location list offset pair: "
86                                "Base address not defined");
87     }
88     DWARFAddressRange Range{Base->Address + E.Value0, Base->Address + E.Value1,
89                             Base->SectionIndex};
90     if (Range.SectionIndex == SectionedAddress::UndefSection)
91       Range.SectionIndex = E.SectionIndex;
92     return DWARFLocationExpression{Range, E.Loc};
93   }
94   case dwarf::DW_LLE_default_location:
95     return DWARFLocationExpression{None, E.Loc};
96   case dwarf::DW_LLE_base_address:
97     Base = SectionedAddress{E.Value0, E.SectionIndex};
98     return None;
99   case dwarf::DW_LLE_start_end:
100     return DWARFLocationExpression{
101         DWARFAddressRange{E.Value0, E.Value1, E.SectionIndex}, E.Loc};
102   case dwarf::DW_LLE_start_length:
103     return DWARFLocationExpression{
104         DWARFAddressRange{E.Value0, E.Value0 + E.Value1, E.SectionIndex},
105         E.Loc};
106   default:
107     llvm_unreachable("unreachable locations list kind");
108   }
109 }
110 
dumpExpression(raw_ostream & OS,DIDumpOptions DumpOpts,ArrayRef<uint8_t> Data,bool IsLittleEndian,unsigned AddressSize,const MCRegisterInfo * MRI,DWARFUnit * U)111 static void dumpExpression(raw_ostream &OS, DIDumpOptions DumpOpts,
112                            ArrayRef<uint8_t> Data, bool IsLittleEndian,
113                            unsigned AddressSize, const MCRegisterInfo *MRI,
114                            DWARFUnit *U) {
115   DWARFDataExtractor Extractor(Data, IsLittleEndian, AddressSize);
116   // Note. We do not pass any format to DWARFExpression, even if the
117   // corresponding unit is known. For now, there is only one operation,
118   // DW_OP_call_ref, which depends on the format; it is rarely used, and
119   // is unexpected in location tables.
120   DWARFExpression(Extractor, AddressSize).print(OS, DumpOpts, MRI, U);
121 }
122 
dumpLocationList(uint64_t * Offset,raw_ostream & OS,Optional<SectionedAddress> BaseAddr,const MCRegisterInfo * MRI,const DWARFObject & Obj,DWARFUnit * U,DIDumpOptions DumpOpts,unsigned Indent) const123 bool DWARFLocationTable::dumpLocationList(uint64_t *Offset, raw_ostream &OS,
124                                           Optional<SectionedAddress> BaseAddr,
125                                           const MCRegisterInfo *MRI,
126                                           const DWARFObject &Obj, DWARFUnit *U,
127                                           DIDumpOptions DumpOpts,
128                                           unsigned Indent) const {
129   DWARFLocationInterpreter Interp(
130       BaseAddr, [U](uint32_t Index) -> Optional<SectionedAddress> {
131         if (U)
132           return U->getAddrOffsetSectionItem(Index);
133         return None;
134       });
135   OS << format("0x%8.8" PRIx64 ": ", *Offset);
136   Error E = visitLocationList(Offset, [&](const DWARFLocationEntry &E) {
137     Expected<Optional<DWARFLocationExpression>> Loc = Interp.Interpret(E);
138     if (!Loc || DumpOpts.DisplayRawContents)
139       dumpRawEntry(E, OS, Indent, DumpOpts, Obj);
140     if (Loc && *Loc) {
141       OS << "\n";
142       OS.indent(Indent);
143       if (DumpOpts.DisplayRawContents)
144         OS << "          => ";
145 
146       DIDumpOptions RangeDumpOpts(DumpOpts);
147       RangeDumpOpts.DisplayRawContents = false;
148       if (Loc.get()->Range)
149         Loc.get()->Range->dump(OS, Data.getAddressSize(), RangeDumpOpts, &Obj);
150       else
151         OS << "<default>";
152     }
153     if (!Loc)
154       consumeError(Loc.takeError());
155 
156     if (E.Kind != dwarf::DW_LLE_base_address &&
157         E.Kind != dwarf::DW_LLE_base_addressx &&
158         E.Kind != dwarf::DW_LLE_end_of_list) {
159       OS << ": ";
160       dumpExpression(OS, DumpOpts, E.Loc, Data.isLittleEndian(),
161                      Data.getAddressSize(), MRI, U);
162     }
163     return true;
164   });
165   if (E) {
166     DumpOpts.RecoverableErrorHandler(std::move(E));
167     return false;
168   }
169   return true;
170 }
171 
visitAbsoluteLocationList(uint64_t Offset,Optional<SectionedAddress> BaseAddr,std::function<Optional<SectionedAddress> (uint32_t)> LookupAddr,function_ref<bool (Expected<DWARFLocationExpression>)> Callback) const172 Error DWARFLocationTable::visitAbsoluteLocationList(
173     uint64_t Offset, Optional<SectionedAddress> BaseAddr,
174     std::function<Optional<SectionedAddress>(uint32_t)> LookupAddr,
175     function_ref<bool(Expected<DWARFLocationExpression>)> Callback) const {
176   DWARFLocationInterpreter Interp(BaseAddr, std::move(LookupAddr));
177   return visitLocationList(&Offset, [&](const DWARFLocationEntry &E) {
178     Expected<Optional<DWARFLocationExpression>> Loc = Interp.Interpret(E);
179     if (!Loc)
180       return Callback(Loc.takeError());
181     if (*Loc)
182       return Callback(**Loc);
183     return true;
184   });
185 }
186 
dump(raw_ostream & OS,const MCRegisterInfo * MRI,const DWARFObject & Obj,DIDumpOptions DumpOpts,Optional<uint64_t> DumpOffset) const187 void DWARFDebugLoc::dump(raw_ostream &OS, const MCRegisterInfo *MRI,
188                          const DWARFObject &Obj, DIDumpOptions DumpOpts,
189                          Optional<uint64_t> DumpOffset) const {
190   auto BaseAddr = None;
191   unsigned Indent = 12;
192   if (DumpOffset) {
193     dumpLocationList(&*DumpOffset, OS, BaseAddr, MRI, Obj, nullptr, DumpOpts,
194                      Indent);
195   } else {
196     uint64_t Offset = 0;
197     StringRef Separator;
198     bool CanContinue = true;
199     while (CanContinue && Data.isValidOffset(Offset)) {
200       OS << Separator;
201       Separator = "\n";
202 
203       CanContinue = dumpLocationList(&Offset, OS, BaseAddr, MRI, Obj, nullptr,
204                                      DumpOpts, Indent);
205       OS << '\n';
206     }
207   }
208 }
209 
visitLocationList(uint64_t * Offset,function_ref<bool (const DWARFLocationEntry &)> Callback) const210 Error DWARFDebugLoc::visitLocationList(
211     uint64_t *Offset,
212     function_ref<bool(const DWARFLocationEntry &)> Callback) const {
213   DataExtractor::Cursor C(*Offset);
214   while (true) {
215     uint64_t SectionIndex;
216     uint64_t Value0 = Data.getRelocatedAddress(C);
217     uint64_t Value1 = Data.getRelocatedAddress(C, &SectionIndex);
218 
219     DWARFLocationEntry E;
220 
221     // The end of any given location list is marked by an end of list entry,
222     // which consists of a 0 for the beginning address offset and a 0 for the
223     // ending address offset. A beginning offset of 0xff...f marks the base
224     // address selection entry.
225     if (Value0 == 0 && Value1 == 0) {
226       E.Kind = dwarf::DW_LLE_end_of_list;
227     } else if (Value0 == (Data.getAddressSize() == 4 ? -1U : -1ULL)) {
228       E.Kind = dwarf::DW_LLE_base_address;
229       E.Value0 = Value1;
230       E.SectionIndex = SectionIndex;
231     } else {
232       E.Kind = dwarf::DW_LLE_offset_pair;
233       E.Value0 = Value0;
234       E.Value1 = Value1;
235       E.SectionIndex = SectionIndex;
236       unsigned Bytes = Data.getU16(C);
237       // A single location description describing the location of the object...
238       Data.getU8(C, E.Loc, Bytes);
239     }
240 
241     if (!C)
242       return C.takeError();
243     if (!Callback(E) || E.Kind == dwarf::DW_LLE_end_of_list)
244       break;
245   }
246   *Offset = C.tell();
247   return Error::success();
248 }
249 
dumpRawEntry(const DWARFLocationEntry & Entry,raw_ostream & OS,unsigned Indent,DIDumpOptions DumpOpts,const DWARFObject & Obj) const250 void DWARFDebugLoc::dumpRawEntry(const DWARFLocationEntry &Entry,
251                                  raw_ostream &OS, unsigned Indent,
252                                  DIDumpOptions DumpOpts,
253                                  const DWARFObject &Obj) const {
254   uint64_t Value0, Value1;
255   switch (Entry.Kind) {
256   case dwarf::DW_LLE_base_address:
257     Value0 = Data.getAddressSize() == 4 ? -1U : -1ULL;
258     Value1 = Entry.Value0;
259     break;
260   case dwarf::DW_LLE_offset_pair:
261     Value0 = Entry.Value0;
262     Value1 = Entry.Value1;
263     break;
264   case dwarf::DW_LLE_end_of_list:
265     return;
266   default:
267     llvm_unreachable("Not possible in DWARF4!");
268   }
269   OS << '\n';
270   OS.indent(Indent);
271   OS << '(' << format_hex(Value0, 2 + Data.getAddressSize() * 2) << ", "
272      << format_hex(Value1, 2 + Data.getAddressSize() * 2) << ')';
273   DWARFFormValue::dumpAddressSection(Obj, OS, DumpOpts, Entry.SectionIndex);
274 }
275 
visitLocationList(uint64_t * Offset,function_ref<bool (const DWARFLocationEntry &)> F) const276 Error DWARFDebugLoclists::visitLocationList(
277     uint64_t *Offset, function_ref<bool(const DWARFLocationEntry &)> F) const {
278 
279   DataExtractor::Cursor C(*Offset);
280   bool Continue = true;
281   while (Continue) {
282     DWARFLocationEntry E;
283     E.Kind = Data.getU8(C);
284     switch (E.Kind) {
285     case dwarf::DW_LLE_end_of_list:
286       break;
287     case dwarf::DW_LLE_base_addressx:
288       E.Value0 = Data.getULEB128(C);
289       break;
290     case dwarf::DW_LLE_startx_endx:
291       E.Value0 = Data.getULEB128(C);
292       E.Value1 = Data.getULEB128(C);
293       break;
294     case dwarf::DW_LLE_startx_length:
295       E.Value0 = Data.getULEB128(C);
296       // Pre-DWARF 5 has different interpretation of the length field. We have
297       // to support both pre- and standartized styles for the compatibility.
298       if (Version < 5)
299         E.Value1 = Data.getU32(C);
300       else
301         E.Value1 = Data.getULEB128(C);
302       break;
303     case dwarf::DW_LLE_offset_pair:
304       E.Value0 = Data.getULEB128(C);
305       E.Value1 = Data.getULEB128(C);
306       E.SectionIndex = SectionedAddress::UndefSection;
307       break;
308     case dwarf::DW_LLE_default_location:
309       break;
310     case dwarf::DW_LLE_base_address:
311       E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
312       break;
313     case dwarf::DW_LLE_start_end:
314       E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
315       E.Value1 = Data.getRelocatedAddress(C);
316       break;
317     case dwarf::DW_LLE_start_length:
318       E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
319       E.Value1 = Data.getULEB128(C);
320       break;
321     default:
322       cantFail(C.takeError());
323       return createStringError(errc::illegal_byte_sequence,
324                                "LLE of kind %x not supported", (int)E.Kind);
325     }
326 
327     if (E.Kind != dwarf::DW_LLE_base_address &&
328         E.Kind != dwarf::DW_LLE_base_addressx &&
329         E.Kind != dwarf::DW_LLE_end_of_list) {
330       unsigned Bytes = Version >= 5 ? Data.getULEB128(C) : Data.getU16(C);
331       // A single location description describing the location of the object...
332       Data.getU8(C, E.Loc, Bytes);
333     }
334 
335     if (!C)
336       return C.takeError();
337     Continue = F(E) && E.Kind != dwarf::DW_LLE_end_of_list;
338   }
339   *Offset = C.tell();
340   return Error::success();
341 }
342 
dumpRawEntry(const DWARFLocationEntry & Entry,raw_ostream & OS,unsigned Indent,DIDumpOptions DumpOpts,const DWARFObject & Obj) const343 void DWARFDebugLoclists::dumpRawEntry(const DWARFLocationEntry &Entry,
344                                       raw_ostream &OS, unsigned Indent,
345                                       DIDumpOptions DumpOpts,
346                                       const DWARFObject &Obj) const {
347   size_t MaxEncodingStringLength = 0;
348 #define HANDLE_DW_LLE(ID, NAME)                                                \
349   MaxEncodingStringLength = std::max(MaxEncodingStringLength,                  \
350                                      dwarf::LocListEncodingString(ID).size());
351 #include "llvm/BinaryFormat/Dwarf.def"
352 
353   OS << "\n";
354   OS.indent(Indent);
355   StringRef EncodingString = dwarf::LocListEncodingString(Entry.Kind);
356   // Unsupported encodings should have been reported during parsing.
357   assert(!EncodingString.empty() && "Unknown loclist entry encoding");
358   OS << format("%-*s(", MaxEncodingStringLength, EncodingString.data());
359   unsigned FieldSize = 2 + 2 * Data.getAddressSize();
360   switch (Entry.Kind) {
361   case dwarf::DW_LLE_end_of_list:
362   case dwarf::DW_LLE_default_location:
363     break;
364   case dwarf::DW_LLE_startx_endx:
365   case dwarf::DW_LLE_startx_length:
366   case dwarf::DW_LLE_offset_pair:
367   case dwarf::DW_LLE_start_end:
368   case dwarf::DW_LLE_start_length:
369     OS << format_hex(Entry.Value0, FieldSize) << ", "
370        << format_hex(Entry.Value1, FieldSize);
371     break;
372   case dwarf::DW_LLE_base_addressx:
373   case dwarf::DW_LLE_base_address:
374     OS << format_hex(Entry.Value0, FieldSize);
375     break;
376   }
377   OS << ')';
378   switch (Entry.Kind) {
379   case dwarf::DW_LLE_base_address:
380   case dwarf::DW_LLE_start_end:
381   case dwarf::DW_LLE_start_length:
382     DWARFFormValue::dumpAddressSection(Obj, OS, DumpOpts, Entry.SectionIndex);
383     break;
384   default:
385     break;
386   }
387 }
388 
dumpRange(uint64_t StartOffset,uint64_t Size,raw_ostream & OS,const MCRegisterInfo * MRI,const DWARFObject & Obj,DIDumpOptions DumpOpts)389 void DWARFDebugLoclists::dumpRange(uint64_t StartOffset, uint64_t Size,
390                                    raw_ostream &OS, const MCRegisterInfo *MRI,
391                                    const DWARFObject &Obj,
392                                    DIDumpOptions DumpOpts) {
393   if (!Data.isValidOffsetForDataOfSize(StartOffset, Size))  {
394     OS << "Invalid dump range\n";
395     return;
396   }
397   uint64_t Offset = StartOffset;
398   StringRef Separator;
399   bool CanContinue = true;
400   while (CanContinue && Offset < StartOffset + Size) {
401     OS << Separator;
402     Separator = "\n";
403 
404     CanContinue = dumpLocationList(&Offset, OS, /*BaseAddr=*/None, MRI, Obj,
405                                    nullptr, DumpOpts, /*Indent=*/12);
406     OS << '\n';
407   }
408 }
409 
log(raw_ostream & OS) const410 void llvm::ResolverError::log(raw_ostream &OS) const {
411   OS << format("unable to resolve indirect address %u for: %s", Index,
412                dwarf::LocListEncodingString(Kind).data());
413 }
414 
415 char llvm::ResolverError::ID;
416