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                                        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                  BaseAddress + E.Begin);
48     OS << format(" 0x%*.*" PRIx64 ")", AddressSize * 2, AddressSize * 2,
49                  BaseAddress + E.End);
50     OS << ": ";
51 
52     dumpExpression(OS, E.Loc, IsLittleEndian, AddressSize, MRI, U);
53   }
54 }
55 
56 DWARFDebugLoc::LocationList const *
57 DWARFDebugLoc::getLocationListAtOffset(uint64_t Offset) const {
58   auto It = partition_point(
59       Locations, [=](const LocationList &L) { 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%8.8" PRIx64 ": ", L.Offset);
69     L.dump(OS, 0, IsLittleEndian, AddressSize, MRI, nullptr, 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 Expected<DWARFDebugLoc::LocationList>
85 DWARFDebugLoc::parseOneLocationList(const DWARFDataExtractor &Data,
86                                     uint64_t *Offset) {
87   LocationList LL;
88   LL.Offset = *Offset;
89   DataExtractor::Cursor C(*Offset);
90 
91   // 2.6.2 Location Lists
92   // A location list entry consists of:
93   while (true) {
94     Entry E;
95 
96     // 1. A beginning address offset. ...
97     E.Begin = Data.getRelocatedAddress(C);
98 
99     // 2. An ending address offset. ...
100     E.End = Data.getRelocatedAddress(C);
101 
102     if (Error Err = C.takeError())
103       return std::move(Err);
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       *Offset = C.tell();
109       return LL;
110     }
111 
112     unsigned Bytes = Data.getU16(C);
113     // A single location description describing the location of the object...
114     Data.getU8(C, E.Loc, Bytes);
115     LL.Entries.push_back(std::move(E));
116   }
117 }
118 
119 void DWARFDebugLoc::parse(const DWARFDataExtractor &data) {
120   IsLittleEndian = data.isLittleEndian();
121   AddressSize = data.getAddressSize();
122 
123   uint64_t Offset = 0;
124   while (Offset < data.getData().size()) {
125     if (auto LL = parseOneLocationList(data, &Offset))
126       Locations.push_back(std::move(*LL));
127     else {
128       logAllUnhandledErrors(LL.takeError(), WithColor::error());
129       break;
130     }
131   }
132 }
133 
134 Expected<DWARFDebugLoclists::LocationList>
135 DWARFDebugLoclists::parseOneLocationList(const DataExtractor &Data,
136                                          uint64_t *Offset, unsigned Version) {
137   LocationList LL;
138   LL.Offset = *Offset;
139   DataExtractor::Cursor C(*Offset);
140 
141   // dwarf::DW_LLE_end_of_list_entry is 0 and indicates the end of the list.
142   while (auto Kind = static_cast<dwarf::LocationListEntry>(Data.getU8(C))) {
143     Entry E;
144     E.Kind = Kind;
145     switch (Kind) {
146     case dwarf::DW_LLE_startx_length:
147       E.Value0 = Data.getULEB128(C);
148       // Pre-DWARF 5 has different interpretation of the length field. We have
149       // to support both pre- and standartized styles for the compatibility.
150       if (Version < 5)
151         E.Value1 = Data.getU32(C);
152       else
153         E.Value1 = Data.getULEB128(C);
154       break;
155     case dwarf::DW_LLE_start_length:
156       E.Value0 = Data.getAddress(C);
157       E.Value1 = Data.getULEB128(C);
158       break;
159     case dwarf::DW_LLE_offset_pair:
160       E.Value0 = Data.getULEB128(C);
161       E.Value1 = Data.getULEB128(C);
162       break;
163     case dwarf::DW_LLE_base_address:
164       E.Value0 = Data.getAddress(C);
165       break;
166     default:
167       cantFail(C.takeError());
168       return createStringError(errc::illegal_byte_sequence,
169                                "LLE of kind %x not supported", (int)Kind);
170     }
171 
172     if (Kind != dwarf::DW_LLE_base_address) {
173       unsigned Bytes = Version >= 5 ? Data.getULEB128(C) : Data.getU16(C);
174       // A single location description describing the location of the object...
175       Data.getU8(C, E.Loc, Bytes);
176     }
177 
178     LL.Entries.push_back(std::move(E));
179   }
180   if (Error Err = C.takeError())
181     return std::move(Err);
182   *Offset = C.tell();
183   return LL;
184 }
185 
186 void DWARFDebugLoclists::parse(DataExtractor data, unsigned Version) {
187   IsLittleEndian = data.isLittleEndian();
188   AddressSize = data.getAddressSize();
189 
190   uint64_t Offset = 0;
191   while (Offset < data.getData().size()) {
192     if (auto LL = parseOneLocationList(data, &Offset, Version))
193       Locations.push_back(std::move(*LL));
194     else {
195       logAllUnhandledErrors(LL.takeError(), WithColor::error());
196       return;
197     }
198   }
199 }
200 
201 DWARFDebugLoclists::LocationList const *
202 DWARFDebugLoclists::getLocationListAtOffset(uint64_t Offset) const {
203   auto It = partition_point(
204       Locations, [=](const LocationList &L) { return L.Offset < Offset; });
205   if (It != Locations.end() && It->Offset == Offset)
206     return &(*It);
207   return nullptr;
208 }
209 
210 void DWARFDebugLoclists::LocationList::dump(raw_ostream &OS, uint64_t BaseAddr,
211                                             bool IsLittleEndian,
212                                             unsigned AddressSize,
213                                             const MCRegisterInfo *MRI,
214                                             DWARFUnit *U,
215                                             unsigned Indent) const {
216   for (const Entry &E : Entries) {
217     switch (E.Kind) {
218     case dwarf::DW_LLE_startx_length:
219       OS << '\n';
220       OS.indent(Indent);
221       OS << "Addr idx " << E.Value0 << " (w/ length " << E.Value1 << "): ";
222       break;
223     case dwarf::DW_LLE_start_length:
224       OS << '\n';
225       OS.indent(Indent);
226       OS << format("[0x%*.*" PRIx64 ", 0x%*.*" PRIx64 "): ", AddressSize * 2,
227                    AddressSize * 2, E.Value0, AddressSize * 2, AddressSize * 2,
228                    E.Value0 + E.Value1);
229       break;
230     case dwarf::DW_LLE_offset_pair:
231       OS << '\n';
232       OS.indent(Indent);
233       OS << format("[0x%*.*" PRIx64 ", 0x%*.*" PRIx64 "): ", AddressSize * 2,
234                    AddressSize * 2, BaseAddr + E.Value0, AddressSize * 2,
235                    AddressSize * 2, BaseAddr + E.Value1);
236       break;
237     case dwarf::DW_LLE_base_address:
238       BaseAddr = E.Value0;
239       break;
240     default:
241       llvm_unreachable("unreachable locations list kind");
242     }
243 
244     dumpExpression(OS, E.Loc, IsLittleEndian, AddressSize, MRI, U);
245   }
246 }
247 
248 void DWARFDebugLoclists::dump(raw_ostream &OS, uint64_t BaseAddr,
249                               const MCRegisterInfo *MRI,
250                               Optional<uint64_t> Offset) const {
251   auto DumpLocationList = [&](const LocationList &L) {
252     OS << format("0x%8.8" PRIx64 ": ", L.Offset);
253     L.dump(OS, BaseAddr, IsLittleEndian, AddressSize, MRI, nullptr, /*Indent=*/12);
254     OS << "\n\n";
255   };
256 
257   if (Offset) {
258     if (auto *L = getLocationListAtOffset(*Offset))
259       DumpLocationList(*L);
260     return;
261   }
262 
263   for (const LocationList &L : Locations) {
264     DumpLocationList(L);
265   }
266 }
267