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_length: {
61     Optional<SectionedAddress> LowPC = LookupAddr(E.Value0);
62     if (!LowPC)
63       return createResolverError(E.Value0, E.Kind);
64     return DWARFLocationExpression{DWARFAddressRange{LowPC->Address,
65                                                      LowPC->Address + E.Value1,
66                                                      LowPC->SectionIndex},
67                                    E.Loc};
68   }
69   case dwarf::DW_LLE_offset_pair:
70     if (!Base) {
71       return createStringError(
72           inconvertibleErrorCode(),
73           "Unable to resolve DW_LLE_offset_pair: base address unknown");
74     }
75     return DWARFLocationExpression{DWARFAddressRange{Base->Address + E.Value0,
76                                                      Base->Address + E.Value1,
77                                                      Base->SectionIndex},
78                                    E.Loc};
79   case dwarf::DW_LLE_base_address:
80     Base = SectionedAddress{E.Value0, SectionedAddress::UndefSection};
81     return None;
82   case dwarf::DW_LLE_start_length:
83     return DWARFLocationExpression{
84         DWARFAddressRange{E.Value0, E.Value0 + E.Value1,
85                           SectionedAddress::UndefSection},
86         E.Loc};
87   default:
88     llvm_unreachable("unreachable locations list kind");
89   }
90 }
91 
92 // When directly dumping the .debug_loc without a compile unit, we have to guess
93 // at the DWARF version. This only affects DW_OP_call_ref, which is a rare
94 // expression that LLVM doesn't produce. Guessing the wrong version means we
95 // won't be able to pretty print expressions in DWARF2 binaries produced by
96 // non-LLVM tools.
97 static void dumpExpression(raw_ostream &OS, ArrayRef<uint8_t> Data,
98                            bool IsLittleEndian, unsigned AddressSize,
99                            const MCRegisterInfo *MRI, DWARFUnit *U) {
100   DWARFDataExtractor Extractor(toStringRef(Data), IsLittleEndian, AddressSize);
101   DWARFExpression(Extractor, dwarf::DWARF_VERSION, AddressSize).print(OS, MRI, U);
102 }
103 
104 bool DWARFLocationTable::dumpLocationList(uint64_t *Offset, raw_ostream &OS,
105                                           Optional<SectionedAddress> BaseAddr,
106                                           const MCRegisterInfo *MRI,
107                                           DWARFUnit *U, DIDumpOptions DumpOpts,
108                                           unsigned Indent) const {
109   DWARFLocationInterpreter Interp(
110       BaseAddr, [U](uint32_t Index) -> Optional<SectionedAddress> {
111         if (U)
112           return U->getAddrOffsetSectionItem(Index);
113         return None;
114       });
115   OS << format("0x%8.8" PRIx64 ": ", *Offset);
116   Error E = visitLocationList(Offset, [&](const DWARFLocationEntry &E) {
117     Expected<Optional<DWARFLocationExpression>> Loc = Interp.Interpret(E);
118     if (!Loc || DumpOpts.DisplayRawContents)
119       dumpRawEntry(E, OS, Indent);
120     if (Loc && *Loc) {
121       OS << "\n";
122       OS.indent(Indent);
123       if (DumpOpts.DisplayRawContents)
124         OS << "          => ";
125 
126       DIDumpOptions RangeDumpOpts(DumpOpts);
127       RangeDumpOpts.DisplayRawContents = false;
128       const DWARFObject *Obj = nullptr;
129       if (U)
130         Obj = &U->getContext().getDWARFObj();
131       Loc.get()->Range->dump(OS, Data.getAddressSize(), RangeDumpOpts, Obj);
132     }
133     if (!Loc)
134       consumeError(Loc.takeError());
135 
136     if (E.Kind != dwarf::DW_LLE_base_address &&
137         E.Kind != dwarf::DW_LLE_base_addressx &&
138         E.Kind != dwarf::DW_LLE_end_of_list) {
139       OS << ": ";
140       dumpExpression(OS, E.Loc, Data.isLittleEndian(), Data.getAddressSize(),
141                      MRI, U);
142     }
143     return true;
144   });
145   if (E) {
146     OS << "\n";
147     OS.indent(Indent);
148     OS << "error: " << toString(std::move(E));
149     return false;
150   }
151   return true;
152 }
153 
154 Error DWARFLocationTable::visitAbsoluteLocationList(
155     uint64_t Offset, Optional<SectionedAddress> BaseAddr,
156     std::function<Optional<SectionedAddress>(uint32_t)> LookupAddr,
157     function_ref<bool(Expected<DWARFLocationExpression>)> Callback) const {
158   DWARFLocationInterpreter Interp(BaseAddr, std::move(LookupAddr));
159   return visitLocationList(&Offset, [&](const DWARFLocationEntry &E) {
160     Expected<Optional<DWARFLocationExpression>> Loc = Interp.Interpret(E);
161     if (!Loc)
162       return Callback(Loc.takeError());
163     if (*Loc)
164       return Callback(**Loc);
165     return true;
166   });
167 }
168 
169 DWARFDebugLoc::LocationList const *
170 DWARFDebugLoc::getLocationListAtOffset(uint64_t Offset) const {
171   auto It = partition_point(
172       Locations, [=](const LocationList &L) { return L.Offset < Offset; });
173   if (It != Locations.end() && It->Offset == Offset)
174     return &(*It);
175   return nullptr;
176 }
177 
178 void DWARFDebugLoc::dump(raw_ostream &OS, const MCRegisterInfo *MRI,
179                          DIDumpOptions DumpOpts,
180                          Optional<uint64_t> DumpOffset) const {
181   auto BaseAddr = None;
182   unsigned Indent = 12;
183   if (DumpOffset) {
184     dumpLocationList(&*DumpOffset, OS, BaseAddr, MRI, nullptr, DumpOpts,
185                      Indent);
186   } else {
187     uint64_t Offset = 0;
188     StringRef Separator;
189     bool CanContinue = true;
190     while (CanContinue && Data.isValidOffset(Offset)) {
191       OS << Separator;
192       Separator = "\n";
193 
194       CanContinue = dumpLocationList(&Offset, OS, BaseAddr, MRI, nullptr,
195                                      DumpOpts, Indent);
196       OS << '\n';
197     }
198   }
199 }
200 
201 Error DWARFDebugLoc::visitLocationList(
202     uint64_t *Offset,
203     function_ref<bool(const DWARFLocationEntry &)> Callback) const {
204   DataExtractor::Cursor C(*Offset);
205   while (true) {
206     uint64_t Value0 = Data.getRelocatedAddress(C);
207     uint64_t Value1 = Data.getRelocatedAddress(C);
208 
209     DWARFLocationEntry E;
210 
211     // The end of any given location list is marked by an end of list entry,
212     // which consists of a 0 for the beginning address offset and a 0 for the
213     // ending address offset. A beginning offset of 0xff...f marks the base
214     // address selection entry.
215     if (Value0 == 0 && Value1 == 0) {
216       E.Kind = dwarf::DW_LLE_end_of_list;
217     } else if (Value0 == (Data.getAddressSize() == 4 ? -1U : -1ULL)) {
218       E.Kind = dwarf::DW_LLE_base_address;
219       E.Value0 = Value1;
220     } else {
221       E.Kind = dwarf::DW_LLE_offset_pair;
222       E.Value0 = Value0;
223       E.Value1 = Value1;
224       unsigned Bytes = Data.getU16(C);
225       // A single location description describing the location of the object...
226       Data.getU8(C, E.Loc, Bytes);
227     }
228 
229     if (!C)
230       return C.takeError();
231     if (!Callback(E) || E.Kind == dwarf::DW_LLE_end_of_list)
232       break;
233   }
234   *Offset = C.tell();
235   return Error::success();
236 }
237 
238 Expected<DWARFDebugLoc::LocationList>
239 DWARFDebugLoc::parseOneLocationList(uint64_t *Offset) {
240   LocationList LL;
241   LL.Offset = *Offset;
242 
243   Error E = visitLocationList(Offset, [&](const DWARFLocationEntry &E) {
244     LL.Entries.push_back(E);
245     return true;
246   });
247   if (E)
248     return std::move(E);
249   return std::move(LL);
250 }
251 
252 void DWARFDebugLoc::parse() {
253   uint64_t Offset = 0;
254   while (Offset < Data.getData().size()) {
255     if (auto LL = parseOneLocationList(&Offset))
256       Locations.push_back(std::move(*LL));
257     else {
258       logAllUnhandledErrors(LL.takeError(), WithColor::error());
259       break;
260     }
261   }
262 }
263 
264 void DWARFDebugLoc::dumpRawEntry(const DWARFLocationEntry &Entry,
265                                  raw_ostream &OS, unsigned Indent) const {
266   uint64_t Value0, Value1;
267   switch (Entry.Kind) {
268   case dwarf::DW_LLE_base_address:
269     Value0 = Data.getAddressSize() == 4 ? -1U : -1ULL;
270     Value1 = Entry.Value0;
271     break;
272   case dwarf::DW_LLE_offset_pair:
273     Value0 = Entry.Value0;
274     Value1 = Entry.Value1;
275     break;
276   case dwarf::DW_LLE_end_of_list:
277     Value0 = Value1 = 0;
278     return;
279   default:
280     llvm_unreachable("Not possible in DWARF4!");
281   }
282   OS << '\n';
283   OS.indent(Indent);
284   OS << '(' << format_hex(Value0, 2 + Data.getAddressSize() * 2) << ", "
285      << format_hex(Value1, 2 + Data.getAddressSize() * 2) << ')';
286 }
287 
288 Error DWARFDebugLoclists::visitLocationList(
289     uint64_t *Offset, function_ref<bool(const DWARFLocationEntry &)> F) const {
290 
291   DataExtractor::Cursor C(*Offset);
292   bool Continue = true;
293   while (Continue) {
294     DWARFLocationEntry E;
295     E.Kind = Data.getU8(C);
296     switch (E.Kind) {
297     case dwarf::DW_LLE_end_of_list:
298       break;
299     case dwarf::DW_LLE_base_addressx:
300       E.Value0 = Data.getULEB128(C);
301       break;
302     case dwarf::DW_LLE_startx_length:
303       E.Value0 = Data.getULEB128(C);
304       // Pre-DWARF 5 has different interpretation of the length field. We have
305       // to support both pre- and standartized styles for the compatibility.
306       if (Version < 5)
307         E.Value1 = Data.getU32(C);
308       else
309         E.Value1 = Data.getULEB128(C);
310       break;
311     case dwarf::DW_LLE_offset_pair:
312       E.Value0 = Data.getULEB128(C);
313       E.Value1 = Data.getULEB128(C);
314       break;
315     case dwarf::DW_LLE_base_address:
316       E.Value0 = Data.getRelocatedAddress(C);
317       break;
318     case dwarf::DW_LLE_start_length:
319       E.Value0 = Data.getRelocatedAddress(C);
320       E.Value1 = Data.getULEB128(C);
321       break;
322     case dwarf::DW_LLE_startx_endx:
323     case dwarf::DW_LLE_default_location:
324     case dwarf::DW_LLE_start_end:
325     default:
326       cantFail(C.takeError());
327       return createStringError(errc::illegal_byte_sequence,
328                                "LLE of kind %x not supported", (int)E.Kind);
329     }
330 
331     if (E.Kind != dwarf::DW_LLE_base_address &&
332         E.Kind != dwarf::DW_LLE_base_addressx &&
333         E.Kind != dwarf::DW_LLE_end_of_list) {
334       unsigned Bytes = Version >= 5 ? Data.getULEB128(C) : Data.getU16(C);
335       // A single location description describing the location of the object...
336       Data.getU8(C, E.Loc, Bytes);
337     }
338 
339     if (!C)
340       return C.takeError();
341     Continue = F(E) && E.Kind != dwarf::DW_LLE_end_of_list;
342   }
343   *Offset = C.tell();
344   return Error::success();
345 }
346 
347 void DWARFDebugLoclists::dumpRawEntry(const DWARFLocationEntry &Entry,
348                                       raw_ostream &OS, unsigned Indent) const {
349   size_t MaxEncodingStringLength = 0;
350 #define HANDLE_DW_LLE(ID, NAME)                                                \
351   MaxEncodingStringLength = std::max(MaxEncodingStringLength,                  \
352                                      dwarf::LocListEncodingString(ID).size());
353 #include "llvm/BinaryFormat/Dwarf.def"
354 
355   OS << "\n";
356   OS.indent(Indent);
357   StringRef EncodingString = dwarf::LocListEncodingString(Entry.Kind);
358   // Unsupported encodings should have been reported during parsing.
359   assert(!EncodingString.empty() && "Unknown loclist entry encoding");
360   OS << format("%-*s(", MaxEncodingStringLength, EncodingString.data());
361   unsigned FieldSize = 2 + 2 * Data.getAddressSize();
362   switch (Entry.Kind) {
363   case dwarf::DW_LLE_startx_length:
364   case dwarf::DW_LLE_start_length:
365   case dwarf::DW_LLE_offset_pair:
366     OS << format_hex(Entry.Value0, FieldSize) << ", "
367        << format_hex(Entry.Value1, FieldSize);
368     break;
369   case dwarf::DW_LLE_base_addressx:
370   case dwarf::DW_LLE_base_address:
371     OS << format_hex(Entry.Value0, FieldSize);
372     break;
373   case dwarf::DW_LLE_end_of_list:
374     break;
375   }
376   OS << ')';
377 }
378 
379 void DWARFDebugLoclists::dumpRange(uint64_t StartOffset, uint64_t Size,
380                                    raw_ostream &OS, const MCRegisterInfo *MRI,
381                                    DIDumpOptions DumpOpts) {
382   if (!Data.isValidOffsetForDataOfSize(StartOffset, Size))  {
383     OS << "Invalid dump range\n";
384     return;
385   }
386   uint64_t Offset = StartOffset;
387   StringRef Separator;
388   bool CanContinue = true;
389   while (CanContinue && Offset < StartOffset + Size) {
390     OS << Separator;
391     Separator = "\n";
392 
393     CanContinue = dumpLocationList(&Offset, OS, /*BaseAddr=*/None, MRI, nullptr,
394                                    DumpOpts, /*Indent=*/12);
395     OS << '\n';
396   }
397 }
398