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 
26 // When directly dumping the .debug_loc without a compile unit, we have to guess
27 // at the DWARF version. This only affects DW_OP_call_ref, which is a rare
28 // expression that LLVM doesn't produce. Guessing the wrong version means we
29 // won't be able to pretty print expressions in DWARF2 binaries produced by
30 // non-LLVM tools.
31 static void dumpExpression(raw_ostream &OS, ArrayRef<uint8_t> Data,
32                            bool IsLittleEndian, unsigned AddressSize,
33                            const MCRegisterInfo *MRI, DWARFUnit *U) {
34   DWARFDataExtractor Extractor(toStringRef(Data), IsLittleEndian, AddressSize);
35   DWARFExpression(Extractor, dwarf::DWARF_VERSION, AddressSize).print(OS, MRI, U);
36 }
37 
38 void DWARFDebugLoc::LocationList::dump(raw_ostream &OS, uint64_t BaseAddress,
39                                        bool IsLittleEndian,
40                                        unsigned AddressSize,
41                                        const MCRegisterInfo *MRI, DWARFUnit *U,
42                                        DIDumpOptions DumpOpts,
43                                        unsigned Indent) const {
44   for (const Entry &E : Entries) {
45     OS << '\n';
46     OS.indent(Indent);
47     OS << format("[0x%*.*" PRIx64 ", ", AddressSize * 2, AddressSize * 2,
48                  BaseAddress + E.Begin);
49     OS << format(" 0x%*.*" PRIx64 ")", AddressSize * 2, AddressSize * 2,
50                  BaseAddress + E.End);
51     OS << ": ";
52 
53     dumpExpression(OS, E.Loc, IsLittleEndian, AddressSize, MRI, U);
54   }
55 }
56 
57 DWARFDebugLoc::LocationList const *
58 DWARFDebugLoc::getLocationListAtOffset(uint64_t Offset) const {
59   auto It = partition_point(
60       Locations, [=](const LocationList &L) { return L.Offset < Offset; });
61   if (It != Locations.end() && It->Offset == Offset)
62     return &(*It);
63   return nullptr;
64 }
65 
66 void DWARFDebugLoc::dump(raw_ostream &OS, const MCRegisterInfo *MRI, DIDumpOptions DumpOpts,
67                          Optional<uint64_t> Offset) const {
68   auto DumpLocationList = [&](const LocationList &L) {
69     OS << format("0x%8.8" PRIx64 ": ", L.Offset);
70     L.dump(OS, 0, IsLittleEndian, AddressSize, MRI, nullptr, DumpOpts, 12);
71     OS << "\n";
72   };
73 
74   if (Offset) {
75     if (auto *L = getLocationListAtOffset(*Offset))
76       DumpLocationList(*L);
77     return;
78   }
79 
80   for (const LocationList &L : Locations) {
81     DumpLocationList(L);
82     if (&L != &Locations.back())
83       OS << '\n';
84   }
85 }
86 
87 Expected<DWARFDebugLoc::LocationList>
88 DWARFDebugLoc::parseOneLocationList(const DWARFDataExtractor &Data,
89                                     uint64_t *Offset) {
90   LocationList LL;
91   LL.Offset = *Offset;
92   AddressSize = Data.getAddressSize();
93   DataExtractor::Cursor C(*Offset);
94 
95   // 2.6.2 Location Lists
96   // A location list entry consists of:
97   while (true) {
98     Entry E;
99 
100     // 1. A beginning address offset. ...
101     E.Begin = Data.getRelocatedAddress(C);
102 
103     // 2. An ending address offset. ...
104     E.End = Data.getRelocatedAddress(C);
105 
106     if (Error Err = C.takeError())
107       return std::move(Err);
108 
109     // The end of any given location list is marked by an end of list entry,
110     // which consists of a 0 for the beginning address offset and a 0 for the
111     // ending address offset.
112     if (E.Begin == 0 && E.End == 0) {
113       *Offset = C.tell();
114       return LL;
115     }
116 
117     if (E.Begin != (AddressSize == 4 ? -1U : -1ULL)) {
118       unsigned Bytes = Data.getU16(C);
119       // A single location description describing the location of the object...
120       Data.getU8(C, E.Loc, Bytes);
121     }
122 
123     LL.Entries.push_back(std::move(E));
124   }
125 }
126 
127 void DWARFDebugLoc::parse(const DWARFDataExtractor &data) {
128   IsLittleEndian = data.isLittleEndian();
129   AddressSize = data.getAddressSize();
130 
131   uint64_t Offset = 0;
132   while (Offset < data.getData().size()) {
133     if (auto LL = parseOneLocationList(data, &Offset))
134       Locations.push_back(std::move(*LL));
135     else {
136       logAllUnhandledErrors(LL.takeError(), WithColor::error());
137       break;
138     }
139   }
140 }
141 
142 Expected<DWARFDebugLoclists::LocationList>
143 DWARFDebugLoclists::parseOneLocationList(const DWARFDataExtractor &Data,
144                                          uint64_t *Offset, unsigned Version) {
145   LocationList LL;
146   LL.Offset = *Offset;
147   DataExtractor::Cursor C(*Offset);
148 
149   // dwarf::DW_LLE_end_of_list_entry is 0 and indicates the end of the list.
150   while (auto Kind = Data.getU8(C)) {
151     Entry E;
152     E.Kind = Kind;
153     E.Offset = C.tell() - 1;
154     switch (Kind) {
155     case dwarf::DW_LLE_base_addressx:
156       E.Value0 = Data.getULEB128(C);
157       break;
158     case dwarf::DW_LLE_startx_length:
159       E.Value0 = Data.getULEB128(C);
160       // Pre-DWARF 5 has different interpretation of the length field. We have
161       // to support both pre- and standartized styles for the compatibility.
162       if (Version < 5)
163         E.Value1 = Data.getU32(C);
164       else
165         E.Value1 = Data.getULEB128(C);
166       break;
167     case dwarf::DW_LLE_start_length:
168       E.Value0 = Data.getRelocatedAddress(C);
169       E.Value1 = Data.getULEB128(C);
170       break;
171     case dwarf::DW_LLE_offset_pair:
172       E.Value0 = Data.getULEB128(C);
173       E.Value1 = Data.getULEB128(C);
174       break;
175     case dwarf::DW_LLE_base_address:
176       E.Value0 = Data.getRelocatedAddress(C);
177       break;
178     default:
179       cantFail(C.takeError());
180       return createStringError(errc::illegal_byte_sequence,
181                                "LLE of kind %x not supported", (int)Kind);
182     }
183 
184     if (Kind != dwarf::DW_LLE_base_address &&
185         Kind != dwarf::DW_LLE_base_addressx) {
186       unsigned Bytes = Version >= 5 ? Data.getULEB128(C) : Data.getU16(C);
187       // A single location description describing the location of the object...
188       Data.getU8(C, E.Loc, Bytes);
189     }
190 
191     LL.Entries.push_back(std::move(E));
192   }
193   if (Error Err = C.takeError())
194     return std::move(Err);
195   Entry E;
196   E.Kind = dwarf::DW_LLE_end_of_list;
197   E.Offset = C.tell() - 1;
198   LL.Entries.push_back(E);
199   *Offset = C.tell();
200   return LL;
201 }
202 
203 void DWARFDebugLoclists::parse(const DWARFDataExtractor &data, uint64_t Offset,
204                                uint64_t EndOffset, uint16_t Version) {
205   IsLittleEndian = data.isLittleEndian();
206   AddressSize = data.getAddressSize();
207 
208   while (Offset < EndOffset) {
209     if (auto LL = parseOneLocationList(data, &Offset, Version))
210       Locations.push_back(std::move(*LL));
211     else {
212       logAllUnhandledErrors(LL.takeError(), WithColor::error());
213       return;
214     }
215   }
216 }
217 
218 DWARFDebugLoclists::LocationList const *
219 DWARFDebugLoclists::getLocationListAtOffset(uint64_t Offset) const {
220   auto It = partition_point(
221       Locations, [=](const LocationList &L) { return L.Offset < Offset; });
222   if (It != Locations.end() && It->Offset == Offset)
223     return &(*It);
224   return nullptr;
225 }
226 
227 void DWARFDebugLoclists::Entry::dump(raw_ostream &OS, uint64_t &BaseAddr,
228                                      bool IsLittleEndian, unsigned AddressSize,
229                                      const MCRegisterInfo *MRI, DWARFUnit *U,
230                                      DIDumpOptions DumpOpts, unsigned Indent,
231                                      size_t MaxEncodingStringLength) const {
232   if (DumpOpts.Verbose) {
233     OS << "\n";
234     OS.indent(Indent);
235     auto EncodingString = dwarf::LocListEncodingString(Kind);
236     // Unsupported encodings should have been reported during parsing.
237     assert(!EncodingString.empty() && "Unknown loclist entry encoding");
238     OS << format("%s%*c", EncodingString.data(),
239                  MaxEncodingStringLength - EncodingString.size() + 1, '(');
240     switch (Kind) {
241     case dwarf::DW_LLE_startx_length:
242     case dwarf::DW_LLE_start_length:
243     case dwarf::DW_LLE_offset_pair:
244       OS << format("0x%*.*" PRIx64 ", 0x%*.*" PRIx64, AddressSize * 2,
245                  AddressSize * 2, Value0, AddressSize * 2, AddressSize * 2,
246                  Value1);
247       break;
248     case dwarf::DW_LLE_base_addressx:
249     case dwarf::DW_LLE_base_address:
250       OS << format("0x%*.*" PRIx64, AddressSize * 2, AddressSize * 2,
251                    Value0);
252       break;
253     case dwarf::DW_LLE_end_of_list:
254       break;
255     }
256     OS << ')';
257   }
258   auto PrintPrefix = [&] {
259     OS << "\n";
260     OS.indent(Indent);
261     if (DumpOpts.Verbose)
262       OS << format("%*s", MaxEncodingStringLength, (const char *)"=> ");
263   };
264   switch (Kind) {
265   case dwarf::DW_LLE_startx_length:
266     PrintPrefix();
267     OS << "Addr idx " << Value0 << " (w/ length " << Value1 << "): ";
268     break;
269   case dwarf::DW_LLE_start_length:
270     PrintPrefix();
271     DWARFAddressRange(Value0, Value0 + Value1)
272         .dump(OS, AddressSize, DumpOpts);
273     OS << ": ";
274     break;
275   case dwarf::DW_LLE_offset_pair:
276     PrintPrefix();
277     DWARFAddressRange(BaseAddr + Value0, BaseAddr + Value1)
278         .dump(OS, AddressSize, DumpOpts);
279     OS << ": ";
280     break;
281   case dwarf::DW_LLE_base_addressx:
282     if (!DumpOpts.Verbose)
283       return;
284     break;
285   case dwarf::DW_LLE_end_of_list:
286     if (!DumpOpts.Verbose)
287       return;
288     break;
289   case dwarf::DW_LLE_base_address:
290     BaseAddr = Value0;
291     if (!DumpOpts.Verbose)
292       return;
293     break;
294   default:
295     llvm_unreachable("unreachable locations list kind");
296   }
297 
298   dumpExpression(OS, Loc, IsLittleEndian, AddressSize, MRI, U);
299 }
300 void DWARFDebugLoclists::LocationList::dump(raw_ostream &OS, uint64_t BaseAddr,
301                                             bool IsLittleEndian,
302                                             unsigned AddressSize,
303                                             const MCRegisterInfo *MRI,
304                                             DWARFUnit *U,
305                                             DIDumpOptions DumpOpts,
306                                             unsigned Indent) const {
307   size_t MaxEncodingStringLength = 0;
308   if (DumpOpts.Verbose)
309     for (const auto &Entry : Entries)
310       MaxEncodingStringLength =
311           std::max(MaxEncodingStringLength,
312                    dwarf::LocListEncodingString(Entry.Kind).size());
313 
314   for (const Entry &E : Entries)
315     E.dump(OS, BaseAddr, IsLittleEndian, AddressSize, MRI, U, DumpOpts, Indent,
316            MaxEncodingStringLength);
317 }
318 
319 void DWARFDebugLoclists::dump(raw_ostream &OS, uint64_t BaseAddr,
320                               const MCRegisterInfo *MRI, DIDumpOptions DumpOpts,
321                               Optional<uint64_t> Offset) const {
322   auto DumpLocationList = [&](const LocationList &L) {
323     OS << format("0x%8.8" PRIx64 ": ", L.Offset);
324     L.dump(OS, BaseAddr, IsLittleEndian, AddressSize, MRI, nullptr, DumpOpts,
325            /*Indent=*/12);
326     OS << "\n";
327   };
328 
329   if (Offset) {
330     if (auto *L = getLocationListAtOffset(*Offset))
331       DumpLocationList(*L);
332     return;
333   }
334 
335   for (const LocationList &L : Locations) {
336     DumpLocationList(L);
337     if (&L != &Locations.back())
338       OS << '\n';
339   }
340 }
341