1 //===- DWARFDebugLoc.cpp --------------------------------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "llvm/DebugInfo/DWARF/DWARFDebugLoc.h"
11 #include "llvm/ADT/StringRef.h"
12 #include "llvm/BinaryFormat/Dwarf.h"
13 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
14 #include "llvm/DebugInfo/DWARF/DWARFExpression.h"
15 #include "llvm/DebugInfo/DWARF/DWARFRelocMap.h"
16 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
17 #include "llvm/Support/Compiler.h"
18 #include "llvm/Support/Format.h"
19 #include "llvm/Support/WithColor.h"
20 #include "llvm/Support/raw_ostream.h"
21 #include <algorithm>
22 #include <cinttypes>
23 #include <cstdint>
24 
25 using namespace llvm;
26 
27 // When directly dumping the .debug_loc without a compile unit, we have to guess
28 // at the DWARF version. This only affects DW_OP_call_ref, which is a rare
29 // expression that LLVM doesn't produce. Guessing the wrong version means we
30 // won't be able to pretty print expressions in DWARF2 binaries produced by
31 // non-LLVM tools.
32 static void dumpExpression(raw_ostream &OS, ArrayRef<char> Data,
33                            bool IsLittleEndian, unsigned AddressSize,
34                            const MCRegisterInfo *MRI) {
35   DWARFDataExtractor Extractor(StringRef(Data.data(), Data.size()),
36                                IsLittleEndian, AddressSize);
37   DWARFExpression(Extractor, dwarf::DWARF_VERSION, AddressSize).print(OS, MRI);
38 }
39 
40 void DWARFDebugLoc::LocationList::dump(raw_ostream &OS, bool IsLittleEndian,
41                                        unsigned AddressSize,
42                                        const MCRegisterInfo *MRI,
43                                        uint64_t BaseAddress,
44                                        unsigned Indent) const {
45   for (const Entry &E : Entries) {
46     OS << '\n';
47     OS.indent(Indent);
48     OS << format("[0x%*.*" PRIx64 ", ", AddressSize * 2, AddressSize * 2,
49                  BaseAddress + E.Begin);
50     OS << format(" 0x%*.*" PRIx64 ")", AddressSize * 2, AddressSize * 2,
51                  BaseAddress + E.End);
52     OS << ": ";
53 
54     dumpExpression(OS, E.Loc, IsLittleEndian, AddressSize, MRI);
55   }
56 }
57 
58 DWARFDebugLoc::LocationList const *
59 DWARFDebugLoc::getLocationListAtOffset(uint64_t Offset) const {
60   auto It = std::lower_bound(
61       Locations.begin(), Locations.end(), Offset,
62       [](const LocationList &L, uint64_t Offset) { return L.Offset < Offset; });
63   if (It != Locations.end() && It->Offset == Offset)
64     return &(*It);
65   return nullptr;
66 }
67 
68 void DWARFDebugLoc::dump(raw_ostream &OS, const MCRegisterInfo *MRI,
69                          Optional<uint64_t> Offset) const {
70   auto DumpLocationList = [&](const LocationList &L) {
71     OS << format("0x%8.8x: ", L.Offset);
72     L.dump(OS, IsLittleEndian, AddressSize, MRI, 0, 12);
73     OS << "\n\n";
74   };
75 
76   if (Offset) {
77     if (auto *L = getLocationListAtOffset(*Offset))
78       DumpLocationList(*L);
79     return;
80   }
81 
82   for (const LocationList &L : Locations) {
83     DumpLocationList(L);
84   }
85 }
86 
87 Optional<DWARFDebugLoc::LocationList>
88 DWARFDebugLoc::parseOneLocationList(DWARFDataExtractor Data, unsigned *Offset) {
89   LocationList LL;
90   LL.Offset = *Offset;
91 
92   // 2.6.2 Location Lists
93   // A location list entry consists of:
94   while (true) {
95     Entry E;
96     if (!Data.isValidOffsetForDataOfSize(*Offset, 2 * Data.getAddressSize())) {
97       WithColor::error() << "location list overflows the debug_loc section.\n";
98       return None;
99     }
100 
101     // 1. A beginning address offset. ...
102     E.Begin = Data.getRelocatedAddress(Offset);
103 
104     // 2. An ending address offset. ...
105     E.End = Data.getRelocatedAddress(Offset);
106 
107     // The end of any given location list is marked by an end of list entry,
108     // which consists of a 0 for the beginning address offset and a 0 for the
109     // ending address offset.
110     if (E.Begin == 0 && E.End == 0)
111       return LL;
112 
113     if (!Data.isValidOffsetForDataOfSize(*Offset, 2)) {
114       WithColor::error() << "location list overflows the debug_loc section.\n";
115       return None;
116     }
117 
118     unsigned Bytes = Data.getU16(Offset);
119     if (!Data.isValidOffsetForDataOfSize(*Offset, Bytes)) {
120       WithColor::error() << "location list overflows the debug_loc section.\n";
121       return None;
122     }
123     // A single location description describing the location of the object...
124     StringRef str = Data.getData().substr(*Offset, Bytes);
125     *Offset += Bytes;
126     E.Loc.reserve(str.size());
127     std::copy(str.begin(), str.end(), std::back_inserter(E.Loc));
128     LL.Entries.push_back(std::move(E));
129   }
130 }
131 
132 void DWARFDebugLoc::parse(const DWARFDataExtractor &data) {
133   IsLittleEndian = data.isLittleEndian();
134   AddressSize = data.getAddressSize();
135 
136   uint32_t Offset = 0;
137   while (data.isValidOffset(Offset + data.getAddressSize() - 1)) {
138     if (auto LL = parseOneLocationList(data, &Offset))
139       Locations.push_back(std::move(*LL));
140     else
141       break;
142   }
143   if (data.isValidOffset(Offset))
144     WithColor::error() << "failed to consume entire .debug_loc section\n";
145 }
146 
147 Optional<DWARFDebugLocDWO::LocationList>
148 DWARFDebugLocDWO::parseOneLocationList(DataExtractor Data, unsigned *Offset) {
149   LocationList LL;
150   LL.Offset = *Offset;
151 
152   // dwarf::DW_LLE_end_of_list_entry is 0 and indicates the end of the list.
153   while (auto Kind =
154              static_cast<dwarf::LocationListEntry>(Data.getU8(Offset))) {
155     if (Kind != dwarf::DW_LLE_startx_length) {
156       WithColor::error() << "dumping support for LLE of kind " << (int)Kind
157                          << " not implemented\n";
158       return None;
159     }
160 
161     Entry E;
162     E.Start = Data.getULEB128(Offset);
163     E.Length = Data.getU32(Offset);
164 
165     unsigned Bytes = Data.getU16(Offset);
166     // A single location description describing the location of the object...
167     StringRef str = Data.getData().substr(*Offset, Bytes);
168     *Offset += Bytes;
169     E.Loc.resize(str.size());
170     std::copy(str.begin(), str.end(), E.Loc.begin());
171 
172     LL.Entries.push_back(std::move(E));
173   }
174   return LL;
175 }
176 
177 void DWARFDebugLocDWO::parse(DataExtractor data) {
178   IsLittleEndian = data.isLittleEndian();
179   AddressSize = data.getAddressSize();
180 
181   uint32_t Offset = 0;
182   while (data.isValidOffset(Offset)) {
183     if (auto LL = parseOneLocationList(data, &Offset))
184       Locations.push_back(std::move(*LL));
185     else
186       return;
187   }
188 }
189 
190 DWARFDebugLocDWO::LocationList const *
191 DWARFDebugLocDWO::getLocationListAtOffset(uint64_t Offset) const {
192   auto It = std::lower_bound(
193       Locations.begin(), Locations.end(), Offset,
194       [](const LocationList &L, uint64_t Offset) { return L.Offset < Offset; });
195   if (It != Locations.end() && It->Offset == Offset)
196     return &(*It);
197   return nullptr;
198 }
199 
200 void DWARFDebugLocDWO::LocationList::dump(raw_ostream &OS, bool IsLittleEndian,
201                                           unsigned AddressSize,
202                                           const MCRegisterInfo *MRI,
203                                           unsigned Indent) const {
204   for (const Entry &E : Entries) {
205     OS << '\n';
206     OS.indent(Indent);
207     OS << "Addr idx " << E.Start << " (w/ length " << E.Length << "): ";
208     dumpExpression(OS, E.Loc, IsLittleEndian, AddressSize, MRI);
209   }
210 }
211 
212 void DWARFDebugLocDWO::dump(raw_ostream &OS, const MCRegisterInfo *MRI,
213                             Optional<uint64_t> Offset) const {
214   auto DumpLocationList = [&](const LocationList &L) {
215     OS << format("0x%8.8x: ", L.Offset);
216     L.dump(OS, IsLittleEndian, AddressSize, MRI, /*Indent=*/12);
217     OS << "\n\n";
218   };
219 
220   if (Offset) {
221     if (auto *L = getLocationListAtOffset(*Offset))
222       DumpLocationList(*L);
223     return;
224   }
225 
226   for (const LocationList &L : Locations) {
227     DumpLocationList(L);
228   }
229 }
230