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                                        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                  E.Begin)
49        << format(" 0x%*.*" PRIx64 ")", AddressSize * 2, AddressSize * 2, E.End);
50     OS << ": ";
51 
52     dumpExpression(OS, E.Loc, IsLittleEndian, AddressSize, MRI);
53   }
54 }
55 
56 DWARFDebugLoc::LocationList const *
57 DWARFDebugLoc::getLocationListAtOffset(uint64_t Offset) const {
58   auto It = std::lower_bound(
59       Locations.begin(), Locations.end(), Offset,
60       [](const LocationList &L, uint64_t Offset) { 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,
67                          Optional<uint64_t> Offset) const {
68   auto DumpLocationList = [&](const LocationList &L) {
69     OS << format("0x%8.8x: ", L.Offset);
70     L.dump(OS, IsLittleEndian, AddressSize, MRI, 12);
71     OS << "\n\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   }
83 }
84 
85 Optional<DWARFDebugLoc::LocationList>
86 DWARFDebugLoc::parseOneLocationList(DWARFDataExtractor Data, unsigned *Offset) {
87   LocationList LL;
88   LL.Offset = *Offset;
89 
90   // 2.6.2 Location Lists
91   // A location list entry consists of:
92   while (true) {
93     Entry E;
94     if (!Data.isValidOffsetForDataOfSize(*Offset, 2 * Data.getAddressSize())) {
95       WithColor::error() << "location list overflows the debug_loc section.\n";
96       return None;
97     }
98 
99     // 1. A beginning address offset. ...
100     E.Begin = Data.getRelocatedAddress(Offset);
101 
102     // 2. An ending address offset. ...
103     E.End = Data.getRelocatedAddress(Offset);
104 
105     // The end of any given location list is marked by an end of list entry,
106     // which consists of a 0 for the beginning address offset and a 0 for the
107     // ending address offset.
108     if (E.Begin == 0 && E.End == 0)
109       return LL;
110 
111     if (!Data.isValidOffsetForDataOfSize(*Offset, 2)) {
112       WithColor::error() << "location list overflows the debug_loc section.\n";
113       return None;
114     }
115 
116     unsigned Bytes = Data.getU16(Offset);
117     if (!Data.isValidOffsetForDataOfSize(*Offset, Bytes)) {
118       WithColor::error() << "location list overflows the debug_loc section.\n";
119       return None;
120     }
121     // A single location description describing the location of the object...
122     StringRef str = Data.getData().substr(*Offset, Bytes);
123     *Offset += Bytes;
124     E.Loc.reserve(str.size());
125     std::copy(str.begin(), str.end(), std::back_inserter(E.Loc));
126     LL.Entries.push_back(std::move(E));
127   }
128 }
129 
130 void DWARFDebugLoc::parse(const DWARFDataExtractor &data) {
131   IsLittleEndian = data.isLittleEndian();
132   AddressSize = data.getAddressSize();
133 
134   uint32_t Offset = 0;
135   while (data.isValidOffset(Offset + data.getAddressSize() - 1)) {
136     if (auto LL = parseOneLocationList(data, &Offset))
137       Locations.push_back(std::move(*LL));
138     else
139       break;
140   }
141   if (data.isValidOffset(Offset))
142     WithColor::error() << "failed to consume entire .debug_loc section\n";
143 }
144 
145 Optional<DWARFDebugLocDWO::LocationList>
146 DWARFDebugLocDWO::parseOneLocationList(DataExtractor Data, unsigned *Offset) {
147   LocationList LL;
148   LL.Offset = *Offset;
149 
150   // dwarf::DW_LLE_end_of_list_entry is 0 and indicates the end of the list.
151   while (auto Kind =
152              static_cast<dwarf::LocationListEntry>(Data.getU8(Offset))) {
153     if (Kind != dwarf::DW_LLE_startx_length) {
154       WithColor::error() << "dumping support for LLE of kind " << (int)Kind
155                          << " not implemented\n";
156       return None;
157     }
158 
159     Entry E;
160     E.Start = Data.getULEB128(Offset);
161     E.Length = Data.getU32(Offset);
162 
163     unsigned Bytes = Data.getU16(Offset);
164     // A single location description describing the location of the object...
165     StringRef str = Data.getData().substr(*Offset, Bytes);
166     *Offset += Bytes;
167     E.Loc.resize(str.size());
168     std::copy(str.begin(), str.end(), E.Loc.begin());
169 
170     LL.Entries.push_back(std::move(E));
171   }
172   return LL;
173 }
174 
175 void DWARFDebugLocDWO::parse(DataExtractor data) {
176   IsLittleEndian = data.isLittleEndian();
177   AddressSize = data.getAddressSize();
178 
179   uint32_t Offset = 0;
180   while (data.isValidOffset(Offset)) {
181     if (auto LL = parseOneLocationList(data, &Offset))
182       Locations.push_back(std::move(*LL));
183     else
184       return;
185   }
186 }
187 
188 DWARFDebugLocDWO::LocationList const *
189 DWARFDebugLocDWO::getLocationListAtOffset(uint64_t Offset) const {
190   auto It = std::lower_bound(
191       Locations.begin(), Locations.end(), Offset,
192       [](const LocationList &L, uint64_t Offset) { return L.Offset < Offset; });
193   if (It != Locations.end() && It->Offset == Offset)
194     return &(*It);
195   return nullptr;
196 }
197 
198 void DWARFDebugLocDWO::LocationList::dump(raw_ostream &OS, bool IsLittleEndian,
199                                           unsigned AddressSize,
200                                           const MCRegisterInfo *MRI,
201                                           unsigned Indent) const {
202   for (const Entry &E : Entries) {
203     OS << '\n';
204     OS.indent(Indent);
205     OS << "Addr idx " << E.Start << " (w/ length " << E.Length << "): ";
206     dumpExpression(OS, E.Loc, IsLittleEndian, AddressSize, MRI);
207   }
208 }
209 
210 void DWARFDebugLocDWO::dump(raw_ostream &OS, const MCRegisterInfo *MRI,
211                             Optional<uint64_t> Offset) const {
212   auto DumpLocationList = [&](const LocationList &L) {
213     OS << format("0x%8.8x: ", L.Offset);
214     L.dump(OS, IsLittleEndian, AddressSize, MRI, /*Indent=*/12);
215     OS << "\n\n";
216   };
217 
218   if (Offset) {
219     if (auto *L = getLocationListAtOffset(*Offset))
220       DumpLocationList(*L);
221     return;
222   }
223 
224   for (const LocationList &L : Locations) {
225     DumpLocationList(L);
226   }
227 }
228