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 
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       *Offset = C.tell();
110       return LL;
111     }
112 
113     if (E.Begin != (AddressSize == 4 ? -1U : -1ULL)) {
114       unsigned Bytes = Data.getU16(C);
115       // A single location description describing the location of the object...
116       Data.getU8(C, E.Loc, Bytes);
117     }
118 
119     LL.Entries.push_back(std::move(E));
120   }
121 }
122 
123 void DWARFDebugLoc::parse(const DWARFDataExtractor &data) {
124   IsLittleEndian = data.isLittleEndian();
125   AddressSize = data.getAddressSize();
126 
127   uint64_t Offset = 0;
128   while (Offset < data.getData().size()) {
129     if (auto LL = parseOneLocationList(data, &Offset))
130       Locations.push_back(std::move(*LL));
131     else {
132       logAllUnhandledErrors(LL.takeError(), WithColor::error());
133       break;
134     }
135   }
136 }
137 
138 Expected<DWARFDebugLoclists::LocationList>
139 DWARFDebugLoclists::parseOneLocationList(const DataExtractor &Data,
140                                          uint64_t *Offset, unsigned Version) {
141   LocationList LL;
142   LL.Offset = *Offset;
143   DataExtractor::Cursor C(*Offset);
144 
145   // dwarf::DW_LLE_end_of_list_entry is 0 and indicates the end of the list.
146   while (auto Kind = Data.getU8(C)) {
147     Entry E;
148     E.Kind = Kind;
149     switch (Kind) {
150     case dwarf::DW_LLE_startx_length:
151       E.Value0 = Data.getULEB128(C);
152       // Pre-DWARF 5 has different interpretation of the length field. We have
153       // to support both pre- and standartized styles for the compatibility.
154       if (Version < 5)
155         E.Value1 = Data.getU32(C);
156       else
157         E.Value1 = Data.getULEB128(C);
158       break;
159     case dwarf::DW_LLE_start_length:
160       E.Value0 = Data.getAddress(C);
161       E.Value1 = Data.getULEB128(C);
162       break;
163     case dwarf::DW_LLE_offset_pair:
164       E.Value0 = Data.getULEB128(C);
165       E.Value1 = Data.getULEB128(C);
166       break;
167     case dwarf::DW_LLE_base_address:
168       E.Value0 = Data.getAddress(C);
169       break;
170     default:
171       cantFail(C.takeError());
172       return createStringError(errc::illegal_byte_sequence,
173                                "LLE of kind %x not supported", (int)Kind);
174     }
175 
176     if (Kind != dwarf::DW_LLE_base_address) {
177       unsigned Bytes = Version >= 5 ? Data.getULEB128(C) : Data.getU16(C);
178       // A single location description describing the location of the object...
179       Data.getU8(C, E.Loc, Bytes);
180     }
181 
182     LL.Entries.push_back(std::move(E));
183   }
184   if (Error Err = C.takeError())
185     return std::move(Err);
186   *Offset = C.tell();
187   return LL;
188 }
189 
190 void DWARFDebugLoclists::parse(DataExtractor data, uint64_t Offset, uint64_t EndOffset, uint16_t Version) {
191   IsLittleEndian = data.isLittleEndian();
192   AddressSize = data.getAddressSize();
193 
194   while (Offset < EndOffset) {
195     if (auto LL = parseOneLocationList(data, &Offset, Version))
196       Locations.push_back(std::move(*LL));
197     else {
198       logAllUnhandledErrors(LL.takeError(), WithColor::error());
199       return;
200     }
201   }
202 }
203 
204 DWARFDebugLoclists::LocationList const *
205 DWARFDebugLoclists::getLocationListAtOffset(uint64_t Offset) const {
206   auto It = partition_point(
207       Locations, [=](const LocationList &L) { return L.Offset < Offset; });
208   if (It != Locations.end() && It->Offset == Offset)
209     return &(*It);
210   return nullptr;
211 }
212 
213 void DWARFDebugLoclists::LocationList::dump(raw_ostream &OS, uint64_t BaseAddr,
214                                             bool IsLittleEndian,
215                                             unsigned AddressSize,
216                                             const MCRegisterInfo *MRI,
217                                             DWARFUnit *U,
218                                             unsigned Indent) const {
219   for (const Entry &E : Entries) {
220     switch (E.Kind) {
221     case dwarf::DW_LLE_startx_length:
222       OS << '\n';
223       OS.indent(Indent);
224       OS << "Addr idx " << E.Value0 << " (w/ length " << E.Value1 << "): ";
225       break;
226     case dwarf::DW_LLE_start_length:
227       OS << '\n';
228       OS.indent(Indent);
229       OS << format("[0x%*.*" PRIx64 ", 0x%*.*" PRIx64 "): ", AddressSize * 2,
230                    AddressSize * 2, E.Value0, AddressSize * 2, AddressSize * 2,
231                    E.Value0 + E.Value1);
232       break;
233     case dwarf::DW_LLE_offset_pair:
234       OS << '\n';
235       OS.indent(Indent);
236       OS << format("[0x%*.*" PRIx64 ", 0x%*.*" PRIx64 "): ", AddressSize * 2,
237                    AddressSize * 2, BaseAddr + E.Value0, AddressSize * 2,
238                    AddressSize * 2, BaseAddr + E.Value1);
239       break;
240     case dwarf::DW_LLE_base_address:
241       BaseAddr = E.Value0;
242       break;
243     default:
244       llvm_unreachable("unreachable locations list kind");
245     }
246 
247     dumpExpression(OS, E.Loc, IsLittleEndian, AddressSize, MRI, U);
248   }
249 }
250 
251 void DWARFDebugLoclists::dump(raw_ostream &OS, uint64_t BaseAddr,
252                               const MCRegisterInfo *MRI,
253                               Optional<uint64_t> Offset) const {
254   auto DumpLocationList = [&](const LocationList &L) {
255     OS << format("0x%8.8" PRIx64 ": ", L.Offset);
256     L.dump(OS, BaseAddr, IsLittleEndian, AddressSize, MRI, nullptr, /*Indent=*/12);
257     OS << "\n\n";
258   };
259 
260   if (Offset) {
261     if (auto *L = getLocationListAtOffset(*Offset))
262       DumpLocationList(*L);
263     return;
264   }
265 
266   for (const LocationList &L : Locations) {
267     DumpLocationList(L);
268   }
269 }
270