xref: /freebsd/contrib/llvm-project/llvm/lib/DebugInfo/DWARF/DWARFDebugLoc.cpp (revision d0b2dbfa0ecf2bbc9709efc5e20baf8e4b44bbbf) 
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   std::optional<object::SectionedAddress> Base;
34   std::function<std::optional<object::SectionedAddress>(uint32_t)> LookupAddr;
35 
36 public:
37   DWARFLocationInterpreter(
38       std::optional<object::SectionedAddress> Base,
39       std::function<std::optional<object::SectionedAddress>(uint32_t)>
40           LookupAddr)
41       : Base(Base), LookupAddr(std::move(LookupAddr)) {}
42 
43   Expected<std::optional<DWARFLocationExpression>>
44   Interpret(const DWARFLocationEntry &E);
45 };
46 } // namespace
47 
48 static Error createResolverError(uint32_t Index, unsigned Kind) {
49   return make_error<ResolverError>(Index, (dwarf::LoclistEntries)Kind);
50 }
51 
52 Expected<std::optional<DWARFLocationExpression>>
53 DWARFLocationInterpreter::Interpret(const DWARFLocationEntry &E) {
54   switch (E.Kind) {
55   case dwarf::DW_LLE_end_of_list:
56     return std::nullopt;
57   case dwarf::DW_LLE_base_addressx: {
58     Base = LookupAddr(E.Value0);
59     if (!Base)
60       return createResolverError(E.Value0, E.Kind);
61     return std::nullopt;
62   }
63   case dwarf::DW_LLE_startx_endx: {
64     std::optional<SectionedAddress> LowPC = LookupAddr(E.Value0);
65     if (!LowPC)
66       return createResolverError(E.Value0, E.Kind);
67     std::optional<SectionedAddress> HighPC = LookupAddr(E.Value1);
68     if (!HighPC)
69       return createResolverError(E.Value1, E.Kind);
70     return DWARFLocationExpression{
71         DWARFAddressRange{LowPC->Address, HighPC->Address, LowPC->SectionIndex},
72         E.Loc};
73   }
74   case dwarf::DW_LLE_startx_length: {
75     std::optional<SectionedAddress> LowPC = LookupAddr(E.Value0);
76     if (!LowPC)
77       return createResolverError(E.Value0, E.Kind);
78     return DWARFLocationExpression{DWARFAddressRange{LowPC->Address,
79                                                      LowPC->Address + E.Value1,
80                                                      LowPC->SectionIndex},
81                                    E.Loc};
82   }
83   case dwarf::DW_LLE_offset_pair: {
84     if (!Base) {
85       return createStringError(inconvertibleErrorCode(),
86                                "Unable to resolve location list offset pair: "
87                                "Base address not defined");
88     }
89     DWARFAddressRange Range{Base->Address + E.Value0, Base->Address + E.Value1,
90                             Base->SectionIndex};
91     if (Range.SectionIndex == SectionedAddress::UndefSection)
92       Range.SectionIndex = E.SectionIndex;
93     return DWARFLocationExpression{Range, E.Loc};
94   }
95   case dwarf::DW_LLE_default_location:
96     return DWARFLocationExpression{std::nullopt, E.Loc};
97   case dwarf::DW_LLE_base_address:
98     Base = SectionedAddress{E.Value0, E.SectionIndex};
99     return std::nullopt;
100   case dwarf::DW_LLE_start_end:
101     return DWARFLocationExpression{
102         DWARFAddressRange{E.Value0, E.Value1, E.SectionIndex}, E.Loc};
103   case dwarf::DW_LLE_start_length:
104     return DWARFLocationExpression{
105         DWARFAddressRange{E.Value0, E.Value0 + E.Value1, E.SectionIndex},
106         E.Loc};
107   default:
108     llvm_unreachable("unreachable locations list kind");
109   }
110 }
111 
112 static void dumpExpression(raw_ostream &OS, DIDumpOptions DumpOpts,
113                            ArrayRef<uint8_t> Data, bool IsLittleEndian,
114                            unsigned AddressSize, 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, U);
121 }
122 
123 bool DWARFLocationTable::dumpLocationList(
124     uint64_t *Offset, raw_ostream &OS, std::optional<SectionedAddress> BaseAddr,
125     const DWARFObject &Obj, DWARFUnit *U, DIDumpOptions DumpOpts,
126     unsigned Indent) const {
127   DWARFLocationInterpreter Interp(
128       BaseAddr, [U](uint32_t Index) -> std::optional<SectionedAddress> {
129         if (U)
130           return U->getAddrOffsetSectionItem(Index);
131         return std::nullopt;
132       });
133   OS << format("0x%8.8" PRIx64 ": ", *Offset);
134   Error E = visitLocationList(Offset, [&](const DWARFLocationEntry &E) {
135     Expected<std::optional<DWARFLocationExpression>> Loc = Interp.Interpret(E);
136     if (!Loc || DumpOpts.DisplayRawContents)
137       dumpRawEntry(E, OS, Indent, DumpOpts, Obj);
138     if (Loc && *Loc) {
139       OS << "\n";
140       OS.indent(Indent);
141       if (DumpOpts.DisplayRawContents)
142         OS << "          => ";
143 
144       DIDumpOptions RangeDumpOpts(DumpOpts);
145       RangeDumpOpts.DisplayRawContents = false;
146       if (Loc.get()->Range)
147         Loc.get()->Range->dump(OS, Data.getAddressSize(), RangeDumpOpts, &Obj);
148       else
149         OS << "<default>";
150     }
151     if (!Loc)
152       consumeError(Loc.takeError());
153 
154     if (E.Kind != dwarf::DW_LLE_base_address &&
155         E.Kind != dwarf::DW_LLE_base_addressx &&
156         E.Kind != dwarf::DW_LLE_end_of_list) {
157       OS << ": ";
158       dumpExpression(OS, DumpOpts, E.Loc, Data.isLittleEndian(),
159                      Data.getAddressSize(), U);
160     }
161     return true;
162   });
163   if (E) {
164     DumpOpts.RecoverableErrorHandler(std::move(E));
165     return false;
166   }
167   return true;
168 }
169 
170 Error DWARFLocationTable::visitAbsoluteLocationList(
171     uint64_t Offset, std::optional<SectionedAddress> BaseAddr,
172     std::function<std::optional<SectionedAddress>(uint32_t)> LookupAddr,
173     function_ref<bool(Expected<DWARFLocationExpression>)> Callback) const {
174   DWARFLocationInterpreter Interp(BaseAddr, std::move(LookupAddr));
175   return visitLocationList(&Offset, [&](const DWARFLocationEntry &E) {
176     Expected<std::optional<DWARFLocationExpression>> Loc = Interp.Interpret(E);
177     if (!Loc)
178       return Callback(Loc.takeError());
179     if (*Loc)
180       return Callback(**Loc);
181     return true;
182   });
183 }
184 
185 void DWARFDebugLoc::dump(raw_ostream &OS, const DWARFObject &Obj,
186                          DIDumpOptions DumpOpts,
187                          std::optional<uint64_t> DumpOffset) const {
188   auto BaseAddr = std::nullopt;
189   unsigned Indent = 12;
190   if (DumpOffset) {
191     dumpLocationList(&*DumpOffset, OS, BaseAddr, Obj, nullptr, DumpOpts,
192                      Indent);
193   } else {
194     uint64_t Offset = 0;
195     StringRef Separator;
196     bool CanContinue = true;
197     while (CanContinue && Data.isValidOffset(Offset)) {
198       OS << Separator;
199       Separator = "\n";
200 
201       CanContinue = dumpLocationList(&Offset, OS, BaseAddr, Obj, nullptr,
202                                      DumpOpts, Indent);
203       OS << '\n';
204     }
205   }
206 }
207 
208 Error DWARFDebugLoc::visitLocationList(
209     uint64_t *Offset,
210     function_ref<bool(const DWARFLocationEntry &)> Callback) const {
211   DataExtractor::Cursor C(*Offset);
212   while (true) {
213     uint64_t SectionIndex;
214     uint64_t Value0 = Data.getRelocatedAddress(C);
215     uint64_t Value1 = Data.getRelocatedAddress(C, &SectionIndex);
216 
217     DWARFLocationEntry E;
218 
219     // The end of any given location list is marked by an end of list entry,
220     // which consists of a 0 for the beginning address offset and a 0 for the
221     // ending address offset. A beginning offset of 0xff...f marks the base
222     // address selection entry.
223     if (Value0 == 0 && Value1 == 0) {
224       E.Kind = dwarf::DW_LLE_end_of_list;
225     } else if (Value0 == (Data.getAddressSize() == 4 ? -1U : -1ULL)) {
226       E.Kind = dwarf::DW_LLE_base_address;
227       E.Value0 = Value1;
228       E.SectionIndex = SectionIndex;
229     } else {
230       E.Kind = dwarf::DW_LLE_offset_pair;
231       E.Value0 = Value0;
232       E.Value1 = Value1;
233       E.SectionIndex = SectionIndex;
234       unsigned Bytes = Data.getU16(C);
235       // A single location description describing the location of the object...
236       Data.getU8(C, E.Loc, Bytes);
237     }
238 
239     if (!C)
240       return C.takeError();
241     if (!Callback(E) || E.Kind == dwarf::DW_LLE_end_of_list)
242       break;
243   }
244   *Offset = C.tell();
245   return Error::success();
246 }
247 
248 void DWARFDebugLoc::dumpRawEntry(const DWARFLocationEntry &Entry,
249                                  raw_ostream &OS, unsigned Indent,
250                                  DIDumpOptions DumpOpts,
251                                  const DWARFObject &Obj) const {
252   uint64_t Value0, Value1;
253   switch (Entry.Kind) {
254   case dwarf::DW_LLE_base_address:
255     Value0 = Data.getAddressSize() == 4 ? -1U : -1ULL;
256     Value1 = Entry.Value0;
257     break;
258   case dwarf::DW_LLE_offset_pair:
259     Value0 = Entry.Value0;
260     Value1 = Entry.Value1;
261     break;
262   case dwarf::DW_LLE_end_of_list:
263     return;
264   default:
265     llvm_unreachable("Not possible in DWARF4!");
266   }
267   OS << '\n';
268   OS.indent(Indent);
269   OS << '(' << format_hex(Value0, 2 + Data.getAddressSize() * 2) << ", "
270      << format_hex(Value1, 2 + Data.getAddressSize() * 2) << ')';
271   DWARFFormValue::dumpAddressSection(Obj, OS, DumpOpts, Entry.SectionIndex);
272 }
273 
274 Error DWARFDebugLoclists::visitLocationList(
275     uint64_t *Offset, function_ref<bool(const DWARFLocationEntry &)> F) const {
276 
277   DataExtractor::Cursor C(*Offset);
278   bool Continue = true;
279   while (Continue) {
280     DWARFLocationEntry E;
281     E.Kind = Data.getU8(C);
282     switch (E.Kind) {
283     case dwarf::DW_LLE_end_of_list:
284       break;
285     case dwarf::DW_LLE_base_addressx:
286       E.Value0 = Data.getULEB128(C);
287       break;
288     case dwarf::DW_LLE_startx_endx:
289       E.Value0 = Data.getULEB128(C);
290       E.Value1 = Data.getULEB128(C);
291       break;
292     case dwarf::DW_LLE_startx_length:
293       E.Value0 = Data.getULEB128(C);
294       // Pre-DWARF 5 has different interpretation of the length field. We have
295       // to support both pre- and standartized styles for the compatibility.
296       if (Version < 5)
297         E.Value1 = Data.getU32(C);
298       else
299         E.Value1 = Data.getULEB128(C);
300       break;
301     case dwarf::DW_LLE_offset_pair:
302       E.Value0 = Data.getULEB128(C);
303       E.Value1 = Data.getULEB128(C);
304       E.SectionIndex = SectionedAddress::UndefSection;
305       break;
306     case dwarf::DW_LLE_default_location:
307       break;
308     case dwarf::DW_LLE_base_address:
309       E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
310       break;
311     case dwarf::DW_LLE_start_end:
312       E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
313       E.Value1 = Data.getRelocatedAddress(C);
314       break;
315     case dwarf::DW_LLE_start_length:
316       E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
317       E.Value1 = Data.getULEB128(C);
318       break;
319     default:
320       cantFail(C.takeError());
321       return createStringError(errc::illegal_byte_sequence,
322                                "LLE of kind %x not supported", (int)E.Kind);
323     }
324 
325     if (E.Kind != dwarf::DW_LLE_base_address &&
326         E.Kind != dwarf::DW_LLE_base_addressx &&
327         E.Kind != dwarf::DW_LLE_end_of_list) {
328       unsigned Bytes = Version >= 5 ? Data.getULEB128(C) : Data.getU16(C);
329       // A single location description describing the location of the object...
330       Data.getU8(C, E.Loc, Bytes);
331     }
332 
333     if (!C)
334       return C.takeError();
335     Continue = F(E) && E.Kind != dwarf::DW_LLE_end_of_list;
336   }
337   *Offset = C.tell();
338   return Error::success();
339 }
340 
341 void DWARFDebugLoclists::dumpRawEntry(const DWARFLocationEntry &Entry,
342                                       raw_ostream &OS, unsigned Indent,
343                                       DIDumpOptions DumpOpts,
344                                       const DWARFObject &Obj) const {
345   size_t MaxEncodingStringLength = 0;
346 #define HANDLE_DW_LLE(ID, NAME)                                                \
347   MaxEncodingStringLength = std::max(MaxEncodingStringLength,                  \
348                                      dwarf::LocListEncodingString(ID).size());
349 #include "llvm/BinaryFormat/Dwarf.def"
350 
351   OS << "\n";
352   OS.indent(Indent);
353   StringRef EncodingString = dwarf::LocListEncodingString(Entry.Kind);
354   // Unsupported encodings should have been reported during parsing.
355   assert(!EncodingString.empty() && "Unknown loclist entry encoding");
356   OS << format("%-*s(", MaxEncodingStringLength, EncodingString.data());
357   unsigned FieldSize = 2 + 2 * Data.getAddressSize();
358   switch (Entry.Kind) {
359   case dwarf::DW_LLE_end_of_list:
360   case dwarf::DW_LLE_default_location:
361     break;
362   case dwarf::DW_LLE_startx_endx:
363   case dwarf::DW_LLE_startx_length:
364   case dwarf::DW_LLE_offset_pair:
365   case dwarf::DW_LLE_start_end:
366   case dwarf::DW_LLE_start_length:
367     OS << format_hex(Entry.Value0, FieldSize) << ", "
368        << format_hex(Entry.Value1, FieldSize);
369     break;
370   case dwarf::DW_LLE_base_addressx:
371   case dwarf::DW_LLE_base_address:
372     OS << format_hex(Entry.Value0, FieldSize);
373     break;
374   }
375   OS << ')';
376   switch (Entry.Kind) {
377   case dwarf::DW_LLE_base_address:
378   case dwarf::DW_LLE_start_end:
379   case dwarf::DW_LLE_start_length:
380     DWARFFormValue::dumpAddressSection(Obj, OS, DumpOpts, Entry.SectionIndex);
381     break;
382   default:
383     break;
384   }
385 }
386 
387 void DWARFDebugLoclists::dumpRange(uint64_t StartOffset, uint64_t Size,
388                                    raw_ostream &OS, const DWARFObject &Obj,
389                                    DIDumpOptions DumpOpts) {
390   if (!Data.isValidOffsetForDataOfSize(StartOffset, Size))  {
391     OS << "Invalid dump range\n";
392     return;
393   }
394   uint64_t Offset = StartOffset;
395   StringRef Separator;
396   bool CanContinue = true;
397   while (CanContinue && Offset < StartOffset + Size) {
398     OS << Separator;
399     Separator = "\n";
400 
401     CanContinue = dumpLocationList(&Offset, OS, /*BaseAddr=*/std::nullopt, Obj,
402                                    nullptr, DumpOpts, /*Indent=*/12);
403     OS << '\n';
404   }
405 }
406 
407 void llvm::ResolverError::log(raw_ostream &OS) const {
408   OS << format("unable to resolve indirect address %u for: %s", Index,
409                dwarf::LocListEncodingString(Kind).data());
410 }
411 
412 char llvm::ResolverError::ID;
413