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                                        DIDumpOptions DumpOpts,
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                  BaseAddress + E.Begin);
49     OS << format(" 0x%*.*" PRIx64 ")", AddressSize * 2, AddressSize * 2,
50                  BaseAddress + E.End);
51     OS << ": ";
52 
53     dumpExpression(OS, E.Loc, IsLittleEndian, AddressSize, MRI, U);
54   }
55 }
56 
57 DWARFDebugLoc::LocationList const *
58 DWARFDebugLoc::getLocationListAtOffset(uint64_t Offset) const {
59   auto It = partition_point(
60       Locations, [=](const LocationList &L) { 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, DIDumpOptions DumpOpts,
67                          Optional<uint64_t> Offset) const {
68   auto DumpLocationList = [&](const LocationList &L) {
69     OS << format("0x%8.8" PRIx64 ": ", L.Offset);
70     L.dump(OS, 0, IsLittleEndian, AddressSize, MRI, nullptr, DumpOpts, 12);
71     OS << "\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     if (&L != &Locations.back())
83       OS << '\n';
84   }
85 }
86 
87 Expected<DWARFDebugLoc::LocationList>
88 DWARFDebugLoc::parseOneLocationList(const DWARFDataExtractor &Data,
89                                     uint64_t *Offset) {
90   LocationList LL;
91   LL.Offset = *Offset;
92   AddressSize = Data.getAddressSize();
93   DataExtractor::Cursor C(*Offset);
94 
95   // 2.6.2 Location Lists
96   // A location list entry consists of:
97   while (true) {
98     Entry E;
99 
100     // 1. A beginning address offset. ...
101     E.Begin = Data.getRelocatedAddress(C);
102 
103     // 2. An ending address offset. ...
104     E.End = Data.getRelocatedAddress(C);
105 
106     if (Error Err = C.takeError())
107       return std::move(Err);
108 
109     // The end of any given location list is marked by an end of list entry,
110     // which consists of a 0 for the beginning address offset and a 0 for the
111     // ending address offset.
112     if (E.Begin == 0 && E.End == 0) {
113       *Offset = C.tell();
114       return LL;
115     }
116 
117     if (E.Begin != (AddressSize == 4 ? -1U : -1ULL)) {
118       unsigned Bytes = Data.getU16(C);
119       // A single location description describing the location of the object...
120       Data.getU8(C, E.Loc, Bytes);
121     }
122 
123     LL.Entries.push_back(std::move(E));
124   }
125 }
126 
127 void DWARFDebugLoc::parse(const DWARFDataExtractor &data) {
128   IsLittleEndian = data.isLittleEndian();
129   AddressSize = data.getAddressSize();
130 
131   uint64_t Offset = 0;
132   while (Offset < data.getData().size()) {
133     if (auto LL = parseOneLocationList(data, &Offset))
134       Locations.push_back(std::move(*LL));
135     else {
136       logAllUnhandledErrors(LL.takeError(), WithColor::error());
137       break;
138     }
139   }
140 }
141 
142 Error DWARFDebugLoclists::visitLocationList(
143     const DWARFDataExtractor &Data, uint64_t *Offset, uint16_t Version,
144     llvm::function_ref<bool(const Entry &)> F) {
145 
146   DataExtractor::Cursor C(*Offset);
147   bool Continue = true;
148   while (Continue) {
149     Entry E;
150     E.Offset = C.tell();
151     E.Kind = Data.getU8(C);
152     switch (E.Kind) {
153     case dwarf::DW_LLE_end_of_list:
154       break;
155     case dwarf::DW_LLE_base_addressx:
156       E.Value0 = Data.getULEB128(C);
157       break;
158     case dwarf::DW_LLE_startx_length:
159       E.Value0 = Data.getULEB128(C);
160       // Pre-DWARF 5 has different interpretation of the length field. We have
161       // to support both pre- and standartized styles for the compatibility.
162       if (Version < 5)
163         E.Value1 = Data.getU32(C);
164       else
165         E.Value1 = Data.getULEB128(C);
166       break;
167     case dwarf::DW_LLE_offset_pair:
168       E.Value0 = Data.getULEB128(C);
169       E.Value1 = Data.getULEB128(C);
170       break;
171     case dwarf::DW_LLE_base_address:
172       E.Value0 = Data.getRelocatedAddress(C);
173       break;
174     case dwarf::DW_LLE_start_length:
175       E.Value0 = Data.getRelocatedAddress(C);
176       E.Value1 = Data.getULEB128(C);
177       break;
178     case dwarf::DW_LLE_startx_endx:
179     case dwarf::DW_LLE_default_location:
180     case dwarf::DW_LLE_start_end:
181     default:
182       cantFail(C.takeError());
183       return createStringError(errc::illegal_byte_sequence,
184                                "LLE of kind %x not supported", (int)E.Kind);
185     }
186 
187     if (E.Kind != dwarf::DW_LLE_base_address &&
188         E.Kind != dwarf::DW_LLE_base_addressx &&
189         E.Kind != dwarf::DW_LLE_end_of_list) {
190       unsigned Bytes = Version >= 5 ? Data.getULEB128(C) : Data.getU16(C);
191       // A single location description describing the location of the object...
192       Data.getU8(C, E.Loc, Bytes);
193     }
194 
195     if (!C)
196       return C.takeError();
197     Continue = F(E) && E.Kind != dwarf::DW_LLE_end_of_list;
198   }
199   *Offset = C.tell();
200   return Error::success();
201 }
202 
203 bool DWARFDebugLoclists::dumpLocationList(const DWARFDataExtractor &Data,
204                                           uint64_t *Offset, uint16_t Version,
205                                           raw_ostream &OS, uint64_t BaseAddr,
206                                           const MCRegisterInfo *MRI,
207                                           DWARFUnit *U, DIDumpOptions DumpOpts,
208                                           unsigned Indent) {
209   size_t MaxEncodingStringLength = 0;
210   if (DumpOpts.Verbose) {
211 #define HANDLE_DW_LLE(ID, NAME)                                                \
212   MaxEncodingStringLength = std::max(MaxEncodingStringLength,                  \
213                                      dwarf::LocListEncodingString(ID).size());
214 #include "llvm/BinaryFormat/Dwarf.def"
215   }
216 
217   OS << format("0x%8.8" PRIx64 ": ", *Offset);
218   Error E = visitLocationList(Data, Offset, Version, [&](const Entry &E) {
219     E.dump(OS, BaseAddr, Data.isLittleEndian(), Data.getAddressSize(), MRI, U,
220            DumpOpts, Indent, MaxEncodingStringLength);
221     return true;
222   });
223   if (E) {
224     OS << "\n";
225     OS.indent(Indent);
226     OS << "error: " << toString(std::move(E));
227     return false;
228   }
229   return true;
230 }
231 
232 void DWARFDebugLoclists::Entry::dump(raw_ostream &OS, uint64_t &BaseAddr,
233                                      bool IsLittleEndian, unsigned AddressSize,
234                                      const MCRegisterInfo *MRI, DWARFUnit *U,
235                                      DIDumpOptions DumpOpts, unsigned Indent,
236                                      size_t MaxEncodingStringLength) const {
237   if (DumpOpts.Verbose) {
238     OS << "\n";
239     OS.indent(Indent);
240     auto EncodingString = dwarf::LocListEncodingString(Kind);
241     // Unsupported encodings should have been reported during parsing.
242     assert(!EncodingString.empty() && "Unknown loclist entry encoding");
243     OS << format("%s%*c", EncodingString.data(),
244                  MaxEncodingStringLength - EncodingString.size() + 1, '(');
245     switch (Kind) {
246     case dwarf::DW_LLE_startx_length:
247     case dwarf::DW_LLE_start_length:
248     case dwarf::DW_LLE_offset_pair:
249       OS << format("0x%*.*" PRIx64 ", 0x%*.*" PRIx64, AddressSize * 2,
250                  AddressSize * 2, Value0, AddressSize * 2, AddressSize * 2,
251                  Value1);
252       break;
253     case dwarf::DW_LLE_base_addressx:
254     case dwarf::DW_LLE_base_address:
255       OS << format("0x%*.*" PRIx64, AddressSize * 2, AddressSize * 2,
256                    Value0);
257       break;
258     case dwarf::DW_LLE_end_of_list:
259       break;
260     }
261     OS << ')';
262   }
263   auto PrintPrefix = [&] {
264     OS << "\n";
265     OS.indent(Indent);
266     if (DumpOpts.Verbose)
267       OS << format("%*s", MaxEncodingStringLength, (const char *)"=> ");
268   };
269   switch (Kind) {
270   case dwarf::DW_LLE_startx_length:
271     PrintPrefix();
272     OS << "Addr idx " << Value0 << " (w/ length " << Value1 << "): ";
273     break;
274   case dwarf::DW_LLE_start_length:
275     PrintPrefix();
276     DWARFAddressRange(Value0, Value0 + Value1)
277         .dump(OS, AddressSize, DumpOpts);
278     OS << ": ";
279     break;
280   case dwarf::DW_LLE_offset_pair:
281     PrintPrefix();
282     DWARFAddressRange(BaseAddr + Value0, BaseAddr + Value1)
283         .dump(OS, AddressSize, DumpOpts);
284     OS << ": ";
285     break;
286   case dwarf::DW_LLE_base_addressx:
287     if (!DumpOpts.Verbose)
288       return;
289     break;
290   case dwarf::DW_LLE_end_of_list:
291     if (!DumpOpts.Verbose)
292       return;
293     break;
294   case dwarf::DW_LLE_base_address:
295     BaseAddr = Value0;
296     if (!DumpOpts.Verbose)
297       return;
298     break;
299   default:
300     llvm_unreachable("unreachable locations list kind");
301   }
302 
303   dumpExpression(OS, Loc, IsLittleEndian, AddressSize, MRI, U);
304 }
305 
306 void DWARFDebugLoclists::dumpRange(const DWARFDataExtractor &Data,
307                                    uint64_t StartOffset, uint64_t Size,
308                                    uint16_t Version, raw_ostream &OS,
309                                    uint64_t BaseAddr, const MCRegisterInfo *MRI,
310                                    DIDumpOptions DumpOpts) {
311   if (!Data.isValidOffsetForDataOfSize(StartOffset, Size))  {
312     OS << "Invalid dump range\n";
313     return;
314   }
315   uint64_t Offset = StartOffset;
316   StringRef Separator;
317   bool CanContinue = true;
318   while (CanContinue && Offset < StartOffset + Size) {
319     OS << Separator;
320     Separator = "\n";
321 
322     CanContinue = dumpLocationList(Data, &Offset, Version, OS, BaseAddr, MRI,
323                                    nullptr, DumpOpts, /*Indent=*/12);
324     OS << '\n';
325   }
326 }
327