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