xref: /freebsd/contrib/llvm-project/llvm/lib/DebugInfo/DWARF/DWARFDebugLoc.cpp (revision 770cf0a5f02dc8983a89c6568d741fbc25baa999) 
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/DWARFExpressionPrinter.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/DebugInfo/DWARF/LowLevel/DWARFExpression.h"
19 #include "llvm/Support/Format.h"
20 #include "llvm/Support/raw_ostream.h"
21 #include <algorithm>
22 #include <cinttypes>
23 #include <cstdint>
24 
25 using namespace llvm;
26 using object::SectionedAddress;
27 
28 namespace llvm {
29 class DWARFObject;
30 }
31 
32 namespace {
33 class DWARFLocationInterpreter {
34   std::optional<object::SectionedAddress> Base;
35   std::function<std::optional<object::SectionedAddress>(uint32_t)> LookupAddr;
36 
37 public:
38   DWARFLocationInterpreter(
39       std::optional<object::SectionedAddress> Base,
40       std::function<std::optional<object::SectionedAddress>(uint32_t)>
41           LookupAddr)
42       : Base(Base), LookupAddr(std::move(LookupAddr)) {}
43 
44   Expected<std::optional<DWARFLocationExpression>>
45   Interpret(const DWARFLocationEntry &E);
46 };
47 } // namespace
48 
49 static Error createResolverError(uint32_t Index, unsigned Kind) {
50   return make_error<ResolverError>(Index, (dwarf::LoclistEntries)Kind);
51 }
52 
53 Expected<std::optional<DWARFLocationExpression>>
54 DWARFLocationInterpreter::Interpret(const DWARFLocationEntry &E) {
55   switch (E.Kind) {
56   case dwarf::DW_LLE_end_of_list:
57     return std::nullopt;
58   case dwarf::DW_LLE_base_addressx: {
59     Base = LookupAddr(E.Value0);
60     if (!Base)
61       return createResolverError(E.Value0, E.Kind);
62     return std::nullopt;
63   }
64   case dwarf::DW_LLE_startx_endx: {
65     std::optional<SectionedAddress> LowPC = LookupAddr(E.Value0);
66     if (!LowPC)
67       return createResolverError(E.Value0, E.Kind);
68     std::optional<SectionedAddress> HighPC = LookupAddr(E.Value1);
69     if (!HighPC)
70       return createResolverError(E.Value1, E.Kind);
71     return DWARFLocationExpression{
72         DWARFAddressRange{LowPC->Address, HighPC->Address, LowPC->SectionIndex},
73         E.Loc};
74   }
75   case dwarf::DW_LLE_startx_length: {
76     std::optional<SectionedAddress> LowPC = LookupAddr(E.Value0);
77     if (!LowPC)
78       return createResolverError(E.Value0, E.Kind);
79     return DWARFLocationExpression{DWARFAddressRange{LowPC->Address,
80                                                      LowPC->Address + E.Value1,
81                                                      LowPC->SectionIndex},
82                                    E.Loc};
83   }
84   case dwarf::DW_LLE_offset_pair: {
85     if (!Base) {
86       return createStringError(inconvertibleErrorCode(),
87                                "Unable to resolve location list offset pair: "
88                                "Base address not defined");
89     }
90     DWARFAddressRange Range{Base->Address + E.Value0, Base->Address + E.Value1,
91                             Base->SectionIndex};
92     if (Range.SectionIndex == SectionedAddress::UndefSection)
93       Range.SectionIndex = E.SectionIndex;
94     return DWARFLocationExpression{Range, E.Loc};
95   }
96   case dwarf::DW_LLE_default_location:
97     return DWARFLocationExpression{std::nullopt, E.Loc};
98   case dwarf::DW_LLE_base_address:
99     Base = SectionedAddress{E.Value0, E.SectionIndex};
100     return std::nullopt;
101   case dwarf::DW_LLE_start_end:
102     return DWARFLocationExpression{
103         DWARFAddressRange{E.Value0, E.Value1, E.SectionIndex}, E.Loc};
104   case dwarf::DW_LLE_start_length:
105     return DWARFLocationExpression{
106         DWARFAddressRange{E.Value0, E.Value0 + E.Value1, E.SectionIndex},
107         E.Loc};
108   default:
109     llvm_unreachable("unreachable locations list kind");
110   }
111 }
112 
113 static void dumpExpression(raw_ostream &OS, DIDumpOptions DumpOpts,
114                            ArrayRef<uint8_t> Data, bool IsLittleEndian,
115                            unsigned AddressSize, DWARFUnit *U) {
116   DWARFDataExtractor Extractor(Data, IsLittleEndian, AddressSize);
117   std::optional<dwarf::DwarfFormat> Format;
118   if (U)
119     Format = U->getFormat();
120   DWARFExpression E(Extractor, AddressSize, Format);
121   printDwarfExpression(&E, OS, DumpOpts, U);
122 }
123 
124 bool DWARFLocationTable::dumpLocationList(
125     uint64_t *Offset, raw_ostream &OS, std::optional<SectionedAddress> BaseAddr,
126     const DWARFObject &Obj, DWARFUnit *U, DIDumpOptions DumpOpts,
127     unsigned Indent) const {
128   DWARFLocationInterpreter Interp(
129       BaseAddr, [U](uint32_t Index) -> std::optional<SectionedAddress> {
130         if (U)
131           return U->getAddrOffsetSectionItem(Index);
132         return std::nullopt;
133       });
134   OS << format("0x%8.8" PRIx64 ": ", *Offset);
135   Error E = visitLocationList(Offset, [&](const DWARFLocationEntry &E) {
136     Expected<std::optional<DWARFLocationExpression>> Loc = Interp.Interpret(E);
137     if (!Loc || DumpOpts.DisplayRawContents)
138       dumpRawEntry(E, OS, Indent, DumpOpts, Obj);
139     if (Loc && *Loc) {
140       OS << "\n";
141       OS.indent(Indent);
142       if (DumpOpts.DisplayRawContents)
143         OS << "          => ";
144 
145       DIDumpOptions RangeDumpOpts(DumpOpts);
146       RangeDumpOpts.DisplayRawContents = false;
147       if (Loc.get()->Range)
148         Loc.get()->Range->dump(OS, Data.getAddressSize(), RangeDumpOpts, &Obj);
149       else
150         OS << "<default>";
151     }
152     if (!Loc)
153       consumeError(Loc.takeError());
154 
155     if (E.Kind != dwarf::DW_LLE_base_address &&
156         E.Kind != dwarf::DW_LLE_base_addressx &&
157         E.Kind != dwarf::DW_LLE_end_of_list) {
158       OS << ": ";
159       dumpExpression(OS, DumpOpts, E.Loc, Data.isLittleEndian(),
160                      Data.getAddressSize(), U);
161     }
162     return true;
163   });
164   if (E) {
165     DumpOpts.RecoverableErrorHandler(std::move(E));
166     return false;
167   }
168   return true;
169 }
170 
171 Error DWARFLocationTable::visitAbsoluteLocationList(
172     uint64_t Offset, std::optional<SectionedAddress> BaseAddr,
173     std::function<std::optional<SectionedAddress>(uint32_t)> LookupAddr,
174     function_ref<bool(Expected<DWARFLocationExpression>)> Callback) const {
175   DWARFLocationInterpreter Interp(BaseAddr, std::move(LookupAddr));
176   return visitLocationList(&Offset, [&](const DWARFLocationEntry &E) {
177     Expected<std::optional<DWARFLocationExpression>> Loc = Interp.Interpret(E);
178     if (!Loc)
179       return Callback(Loc.takeError());
180     if (*Loc)
181       return Callback(**Loc);
182     return true;
183   });
184 }
185 
186 void DWARFDebugLoc::dump(raw_ostream &OS, const DWARFObject &Obj,
187                          DIDumpOptions DumpOpts,
188                          std::optional<uint64_t> DumpOffset) const {
189   auto BaseAddr = std::nullopt;
190   unsigned Indent = 12;
191   if (DumpOffset) {
192     dumpLocationList(&*DumpOffset, OS, BaseAddr, Obj, nullptr, DumpOpts,
193                      Indent);
194   } else {
195     uint64_t Offset = 0;
196     StringRef Separator;
197     bool CanContinue = true;
198     while (CanContinue && Data.isValidOffset(Offset)) {
199       OS << Separator;
200       Separator = "\n";
201 
202       CanContinue = dumpLocationList(&Offset, OS, BaseAddr, Obj, nullptr,
203                                      DumpOpts, Indent);
204       OS << '\n';
205     }
206   }
207 }
208 
209 Error DWARFDebugLoc::visitLocationList(
210     uint64_t *Offset,
211     function_ref<bool(const DWARFLocationEntry &)> Callback) const {
212   DataExtractor::Cursor C(*Offset);
213   while (true) {
214     uint64_t SectionIndex;
215     uint64_t Value0 = Data.getRelocatedAddress(C);
216     uint64_t Value1 = Data.getRelocatedAddress(C, &SectionIndex);
217 
218     DWARFLocationEntry E;
219 
220     // The end of any given location list is marked by an end of list entry,
221     // which consists of a 0 for the beginning address offset and a 0 for the
222     // ending address offset. A beginning offset of 0xff...f marks the base
223     // address selection entry.
224     if (Value0 == 0 && Value1 == 0) {
225       E.Kind = dwarf::DW_LLE_end_of_list;
226     } else if (Value0 == (Data.getAddressSize() == 4 ? -1U : -1ULL)) {
227       E.Kind = dwarf::DW_LLE_base_address;
228       E.Value0 = Value1;
229       E.SectionIndex = SectionIndex;
230     } else {
231       E.Kind = dwarf::DW_LLE_offset_pair;
232       E.Value0 = Value0;
233       E.Value1 = Value1;
234       E.SectionIndex = SectionIndex;
235       unsigned Bytes = Data.getU16(C);
236       // A single location description describing the location of the object...
237       Data.getU8(C, E.Loc, Bytes);
238     }
239 
240     if (!C)
241       return C.takeError();
242     if (!Callback(E) || E.Kind == dwarf::DW_LLE_end_of_list)
243       break;
244   }
245   *Offset = C.tell();
246   return Error::success();
247 }
248 
249 void DWARFDebugLoc::dumpRawEntry(const DWARFLocationEntry &Entry,
250                                  raw_ostream &OS, unsigned Indent,
251                                  DIDumpOptions DumpOpts,
252                                  const DWARFObject &Obj) const {
253   uint64_t Value0, Value1;
254   switch (Entry.Kind) {
255   case dwarf::DW_LLE_base_address:
256     Value0 = Data.getAddressSize() == 4 ? -1U : -1ULL;
257     Value1 = Entry.Value0;
258     break;
259   case dwarf::DW_LLE_offset_pair:
260     Value0 = Entry.Value0;
261     Value1 = Entry.Value1;
262     break;
263   case dwarf::DW_LLE_end_of_list:
264     return;
265   default:
266     llvm_unreachable("Not possible in DWARF4!");
267   }
268   OS << '\n';
269   OS.indent(Indent);
270   OS << '(' << format_hex(Value0, 2 + Data.getAddressSize() * 2) << ", "
271      << format_hex(Value1, 2 + Data.getAddressSize() * 2) << ')';
272   DWARFFormValue::dumpAddressSection(Obj, OS, DumpOpts, Entry.SectionIndex);
273 }
274 
275 Error DWARFDebugLoclists::visitLocationList(
276     uint64_t *Offset, function_ref<bool(const DWARFLocationEntry &)> F) const {
277 
278   DataExtractor::Cursor C(*Offset);
279   bool Continue = true;
280   while (Continue) {
281     DWARFLocationEntry E;
282     E.Kind = Data.getU8(C);
283     switch (E.Kind) {
284     case dwarf::DW_LLE_end_of_list:
285       break;
286     case dwarf::DW_LLE_base_addressx:
287       E.Value0 = Data.getULEB128(C);
288       break;
289     case dwarf::DW_LLE_startx_endx:
290       E.Value0 = Data.getULEB128(C);
291       E.Value1 = Data.getULEB128(C);
292       break;
293     case dwarf::DW_LLE_startx_length:
294       E.Value0 = Data.getULEB128(C);
295       // Pre-DWARF 5 has different interpretation of the length field. We have
296       // to support both pre- and standartized styles for the compatibility.
297       if (Version < 5)
298         E.Value1 = Data.getU32(C);
299       else
300         E.Value1 = Data.getULEB128(C);
301       break;
302     case dwarf::DW_LLE_offset_pair:
303       E.Value0 = Data.getULEB128(C);
304       E.Value1 = Data.getULEB128(C);
305       E.SectionIndex = SectionedAddress::UndefSection;
306       break;
307     case dwarf::DW_LLE_default_location:
308       break;
309     case dwarf::DW_LLE_base_address:
310       E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
311       break;
312     case dwarf::DW_LLE_start_end:
313       E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
314       E.Value1 = Data.getRelocatedAddress(C);
315       break;
316     case dwarf::DW_LLE_start_length:
317       E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
318       E.Value1 = Data.getULEB128(C);
319       break;
320     default:
321       cantFail(C.takeError());
322       return createStringError(errc::illegal_byte_sequence,
323                                "LLE of kind %x not supported", (int)E.Kind);
324     }
325 
326     if (E.Kind != dwarf::DW_LLE_base_address &&
327         E.Kind != dwarf::DW_LLE_base_addressx &&
328         E.Kind != dwarf::DW_LLE_end_of_list) {
329       unsigned Bytes = Version >= 5 ? Data.getULEB128(C) : Data.getU16(C);
330       // A single location description describing the location of the object...
331       Data.getU8(C, E.Loc, Bytes);
332     }
333 
334     if (!C)
335       return C.takeError();
336     Continue = F(E) && E.Kind != dwarf::DW_LLE_end_of_list;
337   }
338   *Offset = C.tell();
339   return Error::success();
340 }
341 
342 void DWARFDebugLoclists::dumpRawEntry(const DWARFLocationEntry &Entry,
343                                       raw_ostream &OS, unsigned Indent,
344                                       DIDumpOptions DumpOpts,
345                                       const DWARFObject &Obj) const {
346   size_t MaxEncodingStringLength = 0;
347 #define HANDLE_DW_LLE(ID, NAME)                                                \
348   MaxEncodingStringLength = std::max(MaxEncodingStringLength,                  \
349                                      dwarf::LocListEncodingString(ID).size());
350 #include "llvm/BinaryFormat/Dwarf.def"
351 
352   OS << "\n";
353   OS.indent(Indent);
354   StringRef EncodingString = dwarf::LocListEncodingString(Entry.Kind);
355   // Unsupported encodings should have been reported during parsing.
356   assert(!EncodingString.empty() && "Unknown loclist entry encoding");
357   OS << format("%-*s(", MaxEncodingStringLength, EncodingString.data());
358   unsigned FieldSize = 2 + 2 * Data.getAddressSize();
359   switch (Entry.Kind) {
360   case dwarf::DW_LLE_end_of_list:
361   case dwarf::DW_LLE_default_location:
362     break;
363   case dwarf::DW_LLE_startx_endx:
364   case dwarf::DW_LLE_startx_length:
365   case dwarf::DW_LLE_offset_pair:
366   case dwarf::DW_LLE_start_end:
367   case dwarf::DW_LLE_start_length:
368     OS << format_hex(Entry.Value0, FieldSize) << ", "
369        << format_hex(Entry.Value1, FieldSize);
370     break;
371   case dwarf::DW_LLE_base_addressx:
372   case dwarf::DW_LLE_base_address:
373     OS << format_hex(Entry.Value0, FieldSize);
374     break;
375   }
376   OS << ')';
377   switch (Entry.Kind) {
378   case dwarf::DW_LLE_base_address:
379   case dwarf::DW_LLE_start_end:
380   case dwarf::DW_LLE_start_length:
381     DWARFFormValue::dumpAddressSection(Obj, OS, DumpOpts, Entry.SectionIndex);
382     break;
383   default:
384     break;
385   }
386 }
387 
388 void DWARFDebugLoclists::dumpRange(uint64_t StartOffset, uint64_t Size,
389                                    raw_ostream &OS, const DWARFObject &Obj,
390                                    DIDumpOptions DumpOpts) {
391   if (!Data.isValidOffsetForDataOfSize(StartOffset, Size))  {
392     OS << "Invalid dump range\n";
393     return;
394   }
395   uint64_t Offset = StartOffset;
396   StringRef Separator;
397   bool CanContinue = true;
398   while (CanContinue && Offset < StartOffset + Size) {
399     OS << Separator;
400     Separator = "\n";
401 
402     CanContinue = dumpLocationList(&Offset, OS, /*BaseAddr=*/std::nullopt, Obj,
403                                    nullptr, DumpOpts, /*Indent=*/12);
404     OS << '\n';
405   }
406 }
407 
408 void llvm::ResolverError::log(raw_ostream &OS) const {
409   OS << format("unable to resolve indirect address %u for: %s", Index,
410                dwarf::LocListEncodingString(Kind).data());
411 }
412 
413 char llvm::ResolverError::ID;
414