xref: /freebsd/contrib/llvm-project/llvm/lib/DebugInfo/DWARF/DWARFDebugLoc.cpp (revision 4f5890a0fb086324a657f3cd7ba1abc57274e0db) 
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 make_error<ResolverError>(Index, (dwarf::LoclistEntries)Kind);
45 }
46 
47 Expected<Optional<DWARFLocationExpression>>
48 DWARFLocationInterpreter::Interpret(const DWARFLocationEntry &E) {
49   switch (E.Kind) {
50   case dwarf::DW_LLE_end_of_list:
51     return None;
52   case dwarf::DW_LLE_base_addressx: {
53     Base = LookupAddr(E.Value0);
54     if (!Base)
55       return createResolverError(E.Value0, E.Kind);
56     return None;
57   }
58   case dwarf::DW_LLE_startx_endx: {
59     Optional<SectionedAddress> LowPC = LookupAddr(E.Value0);
60     if (!LowPC)
61       return createResolverError(E.Value0, E.Kind);
62     Optional<SectionedAddress> HighPC = LookupAddr(E.Value1);
63     if (!HighPC)
64       return createResolverError(E.Value1, E.Kind);
65     return DWARFLocationExpression{
66         DWARFAddressRange{LowPC->Address, HighPC->Address, LowPC->SectionIndex},
67         E.Loc};
68   }
69   case dwarf::DW_LLE_startx_length: {
70     Optional<SectionedAddress> LowPC = LookupAddr(E.Value0);
71     if (!LowPC)
72       return createResolverError(E.Value0, E.Kind);
73     return DWARFLocationExpression{DWARFAddressRange{LowPC->Address,
74                                                      LowPC->Address + E.Value1,
75                                                      LowPC->SectionIndex},
76                                    E.Loc};
77   }
78   case dwarf::DW_LLE_offset_pair: {
79     if (!Base) {
80       return createStringError(inconvertibleErrorCode(),
81                                "Unable to resolve location list offset pair: "
82                                "Base address not defined");
83     }
84     DWARFAddressRange Range{Base->Address + E.Value0, Base->Address + E.Value1,
85                             Base->SectionIndex};
86     if (Range.SectionIndex == SectionedAddress::UndefSection)
87       Range.SectionIndex = E.SectionIndex;
88     return DWARFLocationExpression{Range, E.Loc};
89   }
90   case dwarf::DW_LLE_default_location:
91     return DWARFLocationExpression{None, E.Loc};
92   case dwarf::DW_LLE_base_address:
93     Base = SectionedAddress{E.Value0, E.SectionIndex};
94     return None;
95   case dwarf::DW_LLE_start_end:
96     return DWARFLocationExpression{
97         DWARFAddressRange{E.Value0, E.Value1, E.SectionIndex}, E.Loc};
98   case dwarf::DW_LLE_start_length:
99     return DWARFLocationExpression{
100         DWARFAddressRange{E.Value0, E.Value0 + E.Value1, E.SectionIndex},
101         E.Loc};
102   default:
103     llvm_unreachable("unreachable locations list kind");
104   }
105 }
106 
107 static void dumpExpression(raw_ostream &OS, DIDumpOptions DumpOpts,
108                            ArrayRef<uint8_t> Data, bool IsLittleEndian,
109                            unsigned AddressSize, const MCRegisterInfo *MRI,
110                            DWARFUnit *U) {
111   DWARFDataExtractor Extractor(Data, IsLittleEndian, AddressSize);
112   // Note. We do not pass any format to DWARFExpression, even if the
113   // corresponding unit is known. For now, there is only one operation,
114   // DW_OP_call_ref, which depends on the format; it is rarely used, and
115   // is unexpected in location tables.
116   DWARFExpression(Extractor, AddressSize).print(OS, DumpOpts, MRI, U);
117 }
118 
119 bool DWARFLocationTable::dumpLocationList(uint64_t *Offset, raw_ostream &OS,
120                                           Optional<SectionedAddress> BaseAddr,
121                                           const MCRegisterInfo *MRI,
122                                           const DWARFObject &Obj, DWARFUnit *U,
123                                           DIDumpOptions DumpOpts,
124                                           unsigned Indent) const {
125   DWARFLocationInterpreter Interp(
126       BaseAddr, [U](uint32_t Index) -> Optional<SectionedAddress> {
127         if (U)
128           return U->getAddrOffsetSectionItem(Index);
129         return None;
130       });
131   OS << format("0x%8.8" PRIx64 ": ", *Offset);
132   Error E = visitLocationList(Offset, [&](const DWARFLocationEntry &E) {
133     Expected<Optional<DWARFLocationExpression>> Loc = Interp.Interpret(E);
134     if (!Loc || DumpOpts.DisplayRawContents)
135       dumpRawEntry(E, OS, Indent, DumpOpts, Obj);
136     if (Loc && *Loc) {
137       OS << "\n";
138       OS.indent(Indent);
139       if (DumpOpts.DisplayRawContents)
140         OS << "          => ";
141 
142       DIDumpOptions RangeDumpOpts(DumpOpts);
143       RangeDumpOpts.DisplayRawContents = false;
144       if (Loc.get()->Range)
145         Loc.get()->Range->dump(OS, Data.getAddressSize(), RangeDumpOpts, &Obj);
146       else
147         OS << "<default>";
148     }
149     if (!Loc)
150       consumeError(Loc.takeError());
151 
152     if (E.Kind != dwarf::DW_LLE_base_address &&
153         E.Kind != dwarf::DW_LLE_base_addressx &&
154         E.Kind != dwarf::DW_LLE_end_of_list) {
155       OS << ": ";
156       dumpExpression(OS, DumpOpts, E.Loc, Data.isLittleEndian(),
157                      Data.getAddressSize(), MRI, U);
158     }
159     return true;
160   });
161   if (E) {
162     DumpOpts.RecoverableErrorHandler(std::move(E));
163     return false;
164   }
165   return true;
166 }
167 
168 Error DWARFLocationTable::visitAbsoluteLocationList(
169     uint64_t Offset, Optional<SectionedAddress> BaseAddr,
170     std::function<Optional<SectionedAddress>(uint32_t)> LookupAddr,
171     function_ref<bool(Expected<DWARFLocationExpression>)> Callback) const {
172   DWARFLocationInterpreter Interp(BaseAddr, std::move(LookupAddr));
173   return visitLocationList(&Offset, [&](const DWARFLocationEntry &E) {
174     Expected<Optional<DWARFLocationExpression>> Loc = Interp.Interpret(E);
175     if (!Loc)
176       return Callback(Loc.takeError());
177     if (*Loc)
178       return Callback(**Loc);
179     return true;
180   });
181 }
182 
183 void DWARFDebugLoc::dump(raw_ostream &OS, const MCRegisterInfo *MRI,
184                          const DWARFObject &Obj, DIDumpOptions DumpOpts,
185                          Optional<uint64_t> DumpOffset) const {
186   auto BaseAddr = None;
187   unsigned Indent = 12;
188   if (DumpOffset) {
189     dumpLocationList(&*DumpOffset, OS, BaseAddr, MRI, Obj, nullptr, DumpOpts,
190                      Indent);
191   } else {
192     uint64_t Offset = 0;
193     StringRef Separator;
194     bool CanContinue = true;
195     while (CanContinue && Data.isValidOffset(Offset)) {
196       OS << Separator;
197       Separator = "\n";
198 
199       CanContinue = dumpLocationList(&Offset, OS, BaseAddr, MRI, Obj, nullptr,
200                                      DumpOpts, Indent);
201       OS << '\n';
202     }
203   }
204 }
205 
206 Error DWARFDebugLoc::visitLocationList(
207     uint64_t *Offset,
208     function_ref<bool(const DWARFLocationEntry &)> Callback) const {
209   DataExtractor::Cursor C(*Offset);
210   while (true) {
211     uint64_t SectionIndex;
212     uint64_t Value0 = Data.getRelocatedAddress(C);
213     uint64_t Value1 = Data.getRelocatedAddress(C, &SectionIndex);
214 
215     DWARFLocationEntry E;
216 
217     // The end of any given location list is marked by an end of list entry,
218     // which consists of a 0 for the beginning address offset and a 0 for the
219     // ending address offset. A beginning offset of 0xff...f marks the base
220     // address selection entry.
221     if (Value0 == 0 && Value1 == 0) {
222       E.Kind = dwarf::DW_LLE_end_of_list;
223     } else if (Value0 == (Data.getAddressSize() == 4 ? -1U : -1ULL)) {
224       E.Kind = dwarf::DW_LLE_base_address;
225       E.Value0 = Value1;
226       E.SectionIndex = SectionIndex;
227     } else {
228       E.Kind = dwarf::DW_LLE_offset_pair;
229       E.Value0 = Value0;
230       E.Value1 = Value1;
231       E.SectionIndex = SectionIndex;
232       unsigned Bytes = Data.getU16(C);
233       // A single location description describing the location of the object...
234       Data.getU8(C, E.Loc, Bytes);
235     }
236 
237     if (!C)
238       return C.takeError();
239     if (!Callback(E) || E.Kind == dwarf::DW_LLE_end_of_list)
240       break;
241   }
242   *Offset = C.tell();
243   return Error::success();
244 }
245 
246 void DWARFDebugLoc::dumpRawEntry(const DWARFLocationEntry &Entry,
247                                  raw_ostream &OS, unsigned Indent,
248                                  DIDumpOptions DumpOpts,
249                                  const DWARFObject &Obj) const {
250   uint64_t Value0, Value1;
251   switch (Entry.Kind) {
252   case dwarf::DW_LLE_base_address:
253     Value0 = Data.getAddressSize() == 4 ? -1U : -1ULL;
254     Value1 = Entry.Value0;
255     break;
256   case dwarf::DW_LLE_offset_pair:
257     Value0 = Entry.Value0;
258     Value1 = Entry.Value1;
259     break;
260   case dwarf::DW_LLE_end_of_list:
261     return;
262   default:
263     llvm_unreachable("Not possible in DWARF4!");
264   }
265   OS << '\n';
266   OS.indent(Indent);
267   OS << '(' << format_hex(Value0, 2 + Data.getAddressSize() * 2) << ", "
268      << format_hex(Value1, 2 + Data.getAddressSize() * 2) << ')';
269   DWARFFormValue::dumpAddressSection(Obj, OS, DumpOpts, Entry.SectionIndex);
270 }
271 
272 Error DWARFDebugLoclists::visitLocationList(
273     uint64_t *Offset, function_ref<bool(const DWARFLocationEntry &)> F) const {
274 
275   DataExtractor::Cursor C(*Offset);
276   bool Continue = true;
277   while (Continue) {
278     DWARFLocationEntry E;
279     E.Kind = Data.getU8(C);
280     switch (E.Kind) {
281     case dwarf::DW_LLE_end_of_list:
282       break;
283     case dwarf::DW_LLE_base_addressx:
284       E.Value0 = Data.getULEB128(C);
285       break;
286     case dwarf::DW_LLE_startx_endx:
287       E.Value0 = Data.getULEB128(C);
288       E.Value1 = Data.getULEB128(C);
289       break;
290     case dwarf::DW_LLE_startx_length:
291       E.Value0 = Data.getULEB128(C);
292       // Pre-DWARF 5 has different interpretation of the length field. We have
293       // to support both pre- and standartized styles for the compatibility.
294       if (Version < 5)
295         E.Value1 = Data.getU32(C);
296       else
297         E.Value1 = Data.getULEB128(C);
298       break;
299     case dwarf::DW_LLE_offset_pair:
300       E.Value0 = Data.getULEB128(C);
301       E.Value1 = Data.getULEB128(C);
302       E.SectionIndex = SectionedAddress::UndefSection;
303       break;
304     case dwarf::DW_LLE_default_location:
305       break;
306     case dwarf::DW_LLE_base_address:
307       E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
308       break;
309     case dwarf::DW_LLE_start_end:
310       E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
311       E.Value1 = Data.getRelocatedAddress(C);
312       break;
313     case dwarf::DW_LLE_start_length:
314       E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
315       E.Value1 = Data.getULEB128(C);
316       break;
317     default:
318       cantFail(C.takeError());
319       return createStringError(errc::illegal_byte_sequence,
320                                "LLE of kind %x not supported", (int)E.Kind);
321     }
322 
323     if (E.Kind != dwarf::DW_LLE_base_address &&
324         E.Kind != dwarf::DW_LLE_base_addressx &&
325         E.Kind != dwarf::DW_LLE_end_of_list) {
326       unsigned Bytes = Version >= 5 ? Data.getULEB128(C) : Data.getU16(C);
327       // A single location description describing the location of the object...
328       Data.getU8(C, E.Loc, Bytes);
329     }
330 
331     if (!C)
332       return C.takeError();
333     Continue = F(E) && E.Kind != dwarf::DW_LLE_end_of_list;
334   }
335   *Offset = C.tell();
336   return Error::success();
337 }
338 
339 void DWARFDebugLoclists::dumpRawEntry(const DWARFLocationEntry &Entry,
340                                       raw_ostream &OS, unsigned Indent,
341                                       DIDumpOptions DumpOpts,
342                                       const DWARFObject &Obj) const {
343   size_t MaxEncodingStringLength = 0;
344 #define HANDLE_DW_LLE(ID, NAME)                                                \
345   MaxEncodingStringLength = std::max(MaxEncodingStringLength,                  \
346                                      dwarf::LocListEncodingString(ID).size());
347 #include "llvm/BinaryFormat/Dwarf.def"
348 
349   OS << "\n";
350   OS.indent(Indent);
351   StringRef EncodingString = dwarf::LocListEncodingString(Entry.Kind);
352   // Unsupported encodings should have been reported during parsing.
353   assert(!EncodingString.empty() && "Unknown loclist entry encoding");
354   OS << format("%-*s(", MaxEncodingStringLength, EncodingString.data());
355   unsigned FieldSize = 2 + 2 * Data.getAddressSize();
356   switch (Entry.Kind) {
357   case dwarf::DW_LLE_end_of_list:
358   case dwarf::DW_LLE_default_location:
359     break;
360   case dwarf::DW_LLE_startx_endx:
361   case dwarf::DW_LLE_startx_length:
362   case dwarf::DW_LLE_offset_pair:
363   case dwarf::DW_LLE_start_end:
364   case dwarf::DW_LLE_start_length:
365     OS << format_hex(Entry.Value0, FieldSize) << ", "
366        << format_hex(Entry.Value1, FieldSize);
367     break;
368   case dwarf::DW_LLE_base_addressx:
369   case dwarf::DW_LLE_base_address:
370     OS << format_hex(Entry.Value0, FieldSize);
371     break;
372   }
373   OS << ')';
374   switch (Entry.Kind) {
375   case dwarf::DW_LLE_base_address:
376   case dwarf::DW_LLE_start_end:
377   case dwarf::DW_LLE_start_length:
378     DWARFFormValue::dumpAddressSection(Obj, OS, DumpOpts, Entry.SectionIndex);
379     break;
380   default:
381     break;
382   }
383 }
384 
385 void DWARFDebugLoclists::dumpRange(uint64_t StartOffset, uint64_t Size,
386                                    raw_ostream &OS, const MCRegisterInfo *MRI,
387                                    const DWARFObject &Obj,
388                                    DIDumpOptions DumpOpts) {
389   if (!Data.isValidOffsetForDataOfSize(StartOffset, Size))  {
390     OS << "Invalid dump range\n";
391     return;
392   }
393   uint64_t Offset = StartOffset;
394   StringRef Separator;
395   bool CanContinue = true;
396   while (CanContinue && Offset < StartOffset + Size) {
397     OS << Separator;
398     Separator = "\n";
399 
400     CanContinue = dumpLocationList(&Offset, OS, /*BaseAddr=*/None, MRI, Obj,
401                                    nullptr, DumpOpts, /*Indent=*/12);
402     OS << '\n';
403   }
404 }
405 
406 void llvm::ResolverError::log(raw_ostream &OS) const {
407   OS << format("unable to resolve indirect address %u for: %s", Index,
408                dwarf::LocListEncodingString(Kind).data());
409 }
410 
411 char llvm::ResolverError::ID;
412