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/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<char> Data,
32                            bool IsLittleEndian, unsigned AddressSize,
33                            const MCRegisterInfo *MRI) {
34   DWARFDataExtractor Extractor(StringRef(Data.data(), Data.size()),
35                                IsLittleEndian, AddressSize);
36   DWARFExpression(Extractor, AddressSize, dwarf::DWARF_VERSION).print(OS, MRI);
37 }
38 
39 void DWARFDebugLoc::LocationList::dump(raw_ostream &OS, bool IsLittleEndian,
40                                        unsigned AddressSize,
41                                        const MCRegisterInfo *MRI,
42                                        unsigned Indent) const {
43   for (const Entry &E : Entries) {
44     OS << '\n';
45     OS.indent(Indent);
46     OS << format("[0x%*.*" PRIx64 ", ", AddressSize * 2, AddressSize * 2,
47                  E.Begin)
48        << format(" 0x%*.*" PRIx64 ")", AddressSize * 2, AddressSize * 2, E.End);
49     OS << ": ";
50 
51     dumpExpression(OS, E.Loc, IsLittleEndian, AddressSize, MRI);
52   }
53 }
54 
55 DWARFDebugLoc::LocationList const *
56 DWARFDebugLoc::getLocationListAtOffset(uint64_t Offset) const {
57   auto It = std::lower_bound(
58       Locations.begin(), Locations.end(), Offset,
59       [](const LocationList &L, uint64_t Offset) { return L.Offset < Offset; });
60   if (It != Locations.end() && It->Offset == Offset)
61     return &(*It);
62   return nullptr;
63 }
64 
65 void DWARFDebugLoc::dump(raw_ostream &OS, const MCRegisterInfo *MRI,
66                          Optional<uint64_t> Offset) const {
67   auto DumpLocationList = [&](const LocationList &L) {
68     OS << format("0x%8.8x: ", L.Offset);
69     L.dump(OS, IsLittleEndian, AddressSize, MRI, 12);
70     OS << "\n\n";
71   };
72 
73   if (Offset) {
74     if (auto *L = getLocationListAtOffset(*Offset))
75       DumpLocationList(*L);
76     return;
77   }
78 
79   for (const LocationList &L : Locations) {
80     DumpLocationList(L);
81   }
82 }
83 
84 Optional<DWARFDebugLoc::LocationList>
85 DWARFDebugLoc::parseOneLocationList(DWARFDataExtractor Data, unsigned *Offset) {
86   LocationList LL;
87   LL.Offset = *Offset;
88 
89   // 2.6.2 Location Lists
90   // A location list entry consists of:
91   while (true) {
92     Entry E;
93     if (!Data.isValidOffsetForDataOfSize(*Offset, 2 * Data.getAddressSize())) {
94       llvm::errs() << "Location list overflows the debug_loc section.\n";
95       return None;
96     }
97 
98     // 1. A beginning address offset. ...
99     E.Begin = Data.getRelocatedAddress(Offset);
100 
101     // 2. An ending address offset. ...
102     E.End = Data.getRelocatedAddress(Offset);
103 
104     // The end of any given location list is marked by an end of list entry,
105     // which consists of a 0 for the beginning address offset and a 0 for the
106     // ending address offset.
107     if (E.Begin == 0 && E.End == 0)
108       return LL;
109 
110     if (!Data.isValidOffsetForDataOfSize(*Offset, 2)) {
111       llvm::errs() << "Location list overflows the debug_loc section.\n";
112       return None;
113     }
114 
115     unsigned Bytes = Data.getU16(Offset);
116     if (!Data.isValidOffsetForDataOfSize(*Offset, Bytes)) {
117       llvm::errs() << "Location list overflows the debug_loc section.\n";
118       return None;
119     }
120     // A single location description describing the location of the object...
121     StringRef str = Data.getData().substr(*Offset, Bytes);
122     *Offset += Bytes;
123     E.Loc.reserve(str.size());
124     std::copy(str.begin(), str.end(), std::back_inserter(E.Loc));
125     LL.Entries.push_back(std::move(E));
126   }
127 }
128 
129 void DWARFDebugLoc::parse(const DWARFDataExtractor &data) {
130   IsLittleEndian = data.isLittleEndian();
131   AddressSize = data.getAddressSize();
132 
133   uint32_t Offset = 0;
134   while (data.isValidOffset(Offset + data.getAddressSize() - 1)) {
135     if (auto LL = parseOneLocationList(data, &Offset))
136       Locations.push_back(std::move(*LL));
137     else
138       break;
139   }
140   if (data.isValidOffset(Offset))
141     errs() << "error: failed to consume entire .debug_loc section\n";
142 }
143 
144 Optional<DWARFDebugLocDWO::LocationList>
145 DWARFDebugLocDWO::parseOneLocationList(DataExtractor Data, unsigned *Offset) {
146   LocationList LL;
147   LL.Offset = *Offset;
148 
149   // dwarf::DW_LLE_end_of_list_entry is 0 and indicates the end of the list.
150   while (auto Kind =
151              static_cast<dwarf::LocationListEntry>(Data.getU8(Offset))) {
152     if (Kind != dwarf::DW_LLE_startx_length) {
153       llvm::errs() << "error: dumping support for LLE of kind " << (int)Kind
154                    << " not implemented\n";
155       return None;
156     }
157 
158     Entry E;
159     E.Start = Data.getULEB128(Offset);
160     E.Length = Data.getU32(Offset);
161 
162     unsigned Bytes = Data.getU16(Offset);
163     // A single location description describing the location of the object...
164     StringRef str = Data.getData().substr(*Offset, Bytes);
165     *Offset += Bytes;
166     E.Loc.resize(str.size());
167     std::copy(str.begin(), str.end(), E.Loc.begin());
168 
169     LL.Entries.push_back(std::move(E));
170   }
171   return LL;
172 }
173 
174 void DWARFDebugLocDWO::parse(DataExtractor data) {
175   IsLittleEndian = data.isLittleEndian();
176   AddressSize = data.getAddressSize();
177 
178   uint32_t Offset = 0;
179   while (data.isValidOffset(Offset)) {
180     if (auto LL = parseOneLocationList(data, &Offset))
181       Locations.push_back(std::move(*LL));
182     else
183       return;
184   }
185 }
186 
187 DWARFDebugLocDWO::LocationList const *
188 DWARFDebugLocDWO::getLocationListAtOffset(uint64_t Offset) const {
189   auto It = std::lower_bound(
190       Locations.begin(), Locations.end(), Offset,
191       [](const LocationList &L, uint64_t Offset) { return L.Offset < Offset; });
192   if (It != Locations.end() && It->Offset == Offset)
193     return &(*It);
194   return nullptr;
195 }
196 
197 void DWARFDebugLocDWO::LocationList::dump(raw_ostream &OS, bool IsLittleEndian,
198                                           unsigned AddressSize,
199                                           const MCRegisterInfo *MRI,
200                                           unsigned Indent) const {
201   for (const Entry &E : Entries) {
202     OS << '\n';
203     OS.indent(Indent);
204     OS << "Addr idx " << E.Start << " (w/ length " << E.Length << "): ";
205     dumpExpression(OS, E.Loc, IsLittleEndian, AddressSize, MRI);
206   }
207 }
208 
209 void DWARFDebugLocDWO::dump(raw_ostream &OS, const MCRegisterInfo *MRI,
210                             Optional<uint64_t> Offset) const {
211   auto DumpLocationList = [&](const LocationList &L) {
212     OS << format("0x%8.8x: ", L.Offset);
213     L.dump(OS, IsLittleEndian, AddressSize, MRI, /*Indent=*/12);
214     OS << "\n\n";
215   };
216 
217   if (Offset) {
218     if (auto *L = getLocationListAtOffset(*Offset))
219       DumpLocationList(*L);
220     return;
221   }
222 
223   for (const LocationList &L : Locations) {
224     DumpLocationList(L);
225   }
226 }
227