1 //===- DWARFDebugFrame.h - Parsing of .debug_frame ------------------------===//
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/DWARFDebugFrame.h"
10 #include "llvm/ADT/DenseMap.h"
11 #include "llvm/ADT/StringExtras.h"
12 #include "llvm/ADT/StringRef.h"
13 #include "llvm/BinaryFormat/Dwarf.h"
14 #include "llvm/DebugInfo/DIContext.h"
15 #include "llvm/DebugInfo/DWARF/DWARFCFIPrinter.h"
16 #include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
17 #include "llvm/DebugInfo/DWARF/DWARFExpressionPrinter.h"
18 #include "llvm/DebugInfo/DWARF/DWARFUnwindTablePrinter.h"
19 #include "llvm/DebugInfo/DWARF/LowLevel/DWARFCFIProgram.h"
20 #include "llvm/DebugInfo/DWARF/LowLevel/DWARFExpression.h"
21 #include "llvm/Support/Compiler.h"
22 #include "llvm/Support/DataExtractor.h"
23 #include "llvm/Support/Errc.h"
24 #include "llvm/Support/Error.h"
25 #include "llvm/Support/ErrorHandling.h"
26 #include "llvm/Support/Format.h"
27 #include "llvm/Support/raw_ostream.h"
28 #include <cassert>
29 #include <cinttypes>
30 #include <cstdint>
31 #include <optional>
32
33 using namespace llvm;
34 using namespace dwarf;
35
createUnwindTable(const FDE * Fde)36 Expected<UnwindTable> llvm::dwarf::createUnwindTable(const FDE *Fde) {
37 const CIE *Cie = Fde->getLinkedCIE();
38 if (Cie == nullptr)
39 return createStringError(errc::invalid_argument,
40 "unable to get CIE for FDE at offset 0x%" PRIx64,
41 Fde->getOffset());
42
43 // Rows will be empty if there are no CFI instructions.
44 if (Cie->cfis().empty() && Fde->cfis().empty())
45 return UnwindTable({});
46
47 UnwindTable::RowContainer CieRows;
48 UnwindRow Row;
49 Row.setAddress(Fde->getInitialLocation());
50 if (Error CieError = parseRows(Cie->cfis(), Row, nullptr).moveInto(CieRows))
51 return std::move(CieError);
52 // We need to save the initial locations of registers from the CIE parsing
53 // in case we run into DW_CFA_restore or DW_CFA_restore_extended opcodes.
54 UnwindTable::RowContainer FdeRows;
55 const RegisterLocations InitialLocs = Row.getRegisterLocations();
56 if (Error FdeError =
57 parseRows(Fde->cfis(), Row, &InitialLocs).moveInto(FdeRows))
58 return std::move(FdeError);
59
60 UnwindTable::RowContainer AllRows;
61 AllRows.insert(AllRows.end(), CieRows.begin(), CieRows.end());
62 AllRows.insert(AllRows.end(), FdeRows.begin(), FdeRows.end());
63
64 // May be all the CFI instructions were DW_CFA_nop amd Row becomes empty.
65 // Do not add that to the unwind table.
66 if (Row.getRegisterLocations().hasLocations() ||
67 Row.getCFAValue().getLocation() != UnwindLocation::Unspecified)
68 AllRows.push_back(Row);
69 return UnwindTable(std::move(AllRows));
70 }
71
createUnwindTable(const CIE * Cie)72 Expected<UnwindTable> llvm::dwarf::createUnwindTable(const CIE *Cie) {
73 // Rows will be empty if there are no CFI instructions.
74 if (Cie->cfis().empty())
75 return UnwindTable({});
76
77 UnwindTable::RowContainer Rows;
78 UnwindRow Row;
79 if (Error CieError = parseRows(Cie->cfis(), Row, nullptr).moveInto(Rows))
80 return std::move(CieError);
81 // May be all the CFI instructions were DW_CFA_nop amd Row becomes empty.
82 // Do not add that to the unwind table.
83 if (Row.getRegisterLocations().hasLocations() ||
84 Row.getCFAValue().getLocation() != UnwindLocation::Unspecified)
85 Rows.push_back(Row);
86 return UnwindTable(std::move(Rows));
87 }
88
89 // Returns the CIE identifier to be used by the requested format.
90 // CIE ids for .debug_frame sections are defined in Section 7.24 of DWARFv5.
91 // For CIE ID in .eh_frame sections see
92 // https://refspecs.linuxfoundation.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html
getCIEId(bool IsDWARF64,bool IsEH)93 constexpr uint64_t getCIEId(bool IsDWARF64, bool IsEH) {
94 if (IsEH)
95 return 0;
96 if (IsDWARF64)
97 return DW64_CIE_ID;
98 return DW_CIE_ID;
99 }
100
dump(raw_ostream & OS,DIDumpOptions DumpOpts) const101 void CIE::dump(raw_ostream &OS, DIDumpOptions DumpOpts) const {
102 // A CIE with a zero length is a terminator entry in the .eh_frame section.
103 if (DumpOpts.IsEH && Length == 0) {
104 OS << format("%08" PRIx64, Offset) << " ZERO terminator\n";
105 return;
106 }
107
108 OS << format("%08" PRIx64, Offset)
109 << format(" %0*" PRIx64, IsDWARF64 ? 16 : 8, Length)
110 << format(" %0*" PRIx64, IsDWARF64 && !DumpOpts.IsEH ? 16 : 8,
111 getCIEId(IsDWARF64, DumpOpts.IsEH))
112 << " CIE\n"
113 << " Format: " << FormatString(IsDWARF64) << "\n";
114 if (DumpOpts.IsEH && Version != 1)
115 OS << "WARNING: unsupported CIE version\n";
116 OS << format(" Version: %d\n", Version)
117 << " Augmentation: \"" << Augmentation << "\"\n";
118 if (Version >= 4) {
119 OS << format(" Address size: %u\n", (uint32_t)AddressSize);
120 OS << format(" Segment desc size: %u\n",
121 (uint32_t)SegmentDescriptorSize);
122 }
123 OS << format(" Code alignment factor: %u\n", (uint32_t)CodeAlignmentFactor);
124 OS << format(" Data alignment factor: %d\n", (int32_t)DataAlignmentFactor);
125 OS << format(" Return address column: %d\n", (int32_t)ReturnAddressRegister);
126 if (Personality)
127 OS << format(" Personality Address: %016" PRIx64 "\n", *Personality);
128 if (!AugmentationData.empty()) {
129 OS << " Augmentation data: ";
130 for (uint8_t Byte : AugmentationData)
131 OS << ' ' << hexdigit(Byte >> 4) << hexdigit(Byte & 0xf);
132 OS << "\n";
133 }
134 OS << "\n";
135 printCFIProgram(CFIs, OS, DumpOpts, /*IndentLevel=*/1,
136 /*InitialLocation=*/{});
137 OS << "\n";
138
139 if (Expected<UnwindTable> RowsOrErr = createUnwindTable(this))
140 printUnwindTable(*RowsOrErr, OS, DumpOpts, 1);
141 else {
142 DumpOpts.RecoverableErrorHandler(joinErrors(
143 createStringError(errc::invalid_argument,
144 "decoding the CIE opcodes into rows failed"),
145 RowsOrErr.takeError()));
146 }
147 OS << "\n";
148 }
149
dump(raw_ostream & OS,DIDumpOptions DumpOpts) const150 void FDE::dump(raw_ostream &OS, DIDumpOptions DumpOpts) const {
151 OS << format("%08" PRIx64, Offset)
152 << format(" %0*" PRIx64, IsDWARF64 ? 16 : 8, Length)
153 << format(" %0*" PRIx64, IsDWARF64 && !DumpOpts.IsEH ? 16 : 8, CIEPointer)
154 << " FDE cie=";
155 if (LinkedCIE)
156 OS << format("%08" PRIx64, LinkedCIE->getOffset());
157 else
158 OS << "<invalid offset>";
159 OS << format(" pc=%08" PRIx64 "...%08" PRIx64 "\n", InitialLocation,
160 InitialLocation + AddressRange);
161 OS << " Format: " << FormatString(IsDWARF64) << "\n";
162 if (LSDAAddress)
163 OS << format(" LSDA Address: %016" PRIx64 "\n", *LSDAAddress);
164 printCFIProgram(CFIs, OS, DumpOpts, /*IndentLevel=*/1, InitialLocation);
165 OS << "\n";
166
167 if (Expected<UnwindTable> RowsOrErr = createUnwindTable(this))
168 printUnwindTable(*RowsOrErr, OS, DumpOpts, 1);
169 else {
170 DumpOpts.RecoverableErrorHandler(joinErrors(
171 createStringError(errc::invalid_argument,
172 "decoding the FDE opcodes into rows failed"),
173 RowsOrErr.takeError()));
174 }
175 OS << "\n";
176 }
177
DWARFDebugFrame(Triple::ArchType Arch,bool IsEH,uint64_t EHFrameAddress)178 DWARFDebugFrame::DWARFDebugFrame(Triple::ArchType Arch,
179 bool IsEH, uint64_t EHFrameAddress)
180 : Arch(Arch), IsEH(IsEH), EHFrameAddress(EHFrameAddress) {}
181
182 DWARFDebugFrame::~DWARFDebugFrame() = default;
183
dumpDataAux(DataExtractor Data,uint64_t Offset,int Length)184 static void LLVM_ATTRIBUTE_UNUSED dumpDataAux(DataExtractor Data,
185 uint64_t Offset, int Length) {
186 errs() << "DUMP: ";
187 for (int i = 0; i < Length; ++i) {
188 uint8_t c = Data.getU8(&Offset);
189 errs().write_hex(c); errs() << " ";
190 }
191 errs() << "\n";
192 }
193
parse(DWARFDataExtractor Data)194 Error DWARFDebugFrame::parse(DWARFDataExtractor Data) {
195 uint64_t Offset = 0;
196 DenseMap<uint64_t, CIE *> CIEs;
197
198 while (Data.isValidOffset(Offset)) {
199 uint64_t StartOffset = Offset;
200
201 uint64_t Length;
202 DwarfFormat Format;
203 std::tie(Length, Format) = Data.getInitialLength(&Offset);
204 bool IsDWARF64 = Format == DWARF64;
205
206 // If the Length is 0, then this CIE is a terminator. We add it because some
207 // dumper tools might need it to print something special for such entries
208 // (e.g. llvm-objdump --dwarf=frames prints "ZERO terminator").
209 if (Length == 0) {
210 auto Cie = std::make_unique<CIE>(
211 IsDWARF64, StartOffset, 0, 0, SmallString<8>(), 0, 0, 0, 0, 0,
212 SmallString<8>(), 0, 0, std::nullopt, std::nullopt, Arch);
213 CIEs[StartOffset] = Cie.get();
214 Entries.push_back(std::move(Cie));
215 break;
216 }
217
218 // At this point, Offset points to the next field after Length.
219 // Length is the structure size excluding itself. Compute an offset one
220 // past the end of the structure (needed to know how many instructions to
221 // read).
222 uint64_t StartStructureOffset = Offset;
223 uint64_t EndStructureOffset = Offset + Length;
224
225 // The Id field's size depends on the DWARF format
226 Error Err = Error::success();
227 uint64_t Id = Data.getRelocatedValue((IsDWARF64 && !IsEH) ? 8 : 4, &Offset,
228 /*SectionIndex=*/nullptr, &Err);
229 if (Err)
230 return Err;
231
232 if (Id == getCIEId(IsDWARF64, IsEH)) {
233 uint8_t Version = Data.getU8(&Offset);
234 const char *Augmentation = Data.getCStr(&Offset);
235 StringRef AugmentationString(Augmentation ? Augmentation : "");
236 uint8_t AddressSize = Version < 4 ? Data.getAddressSize() :
237 Data.getU8(&Offset);
238 Data.setAddressSize(AddressSize);
239 uint8_t SegmentDescriptorSize = Version < 4 ? 0 : Data.getU8(&Offset);
240 uint64_t CodeAlignmentFactor = Data.getULEB128(&Offset);
241 int64_t DataAlignmentFactor = Data.getSLEB128(&Offset);
242 uint64_t ReturnAddressRegister =
243 Version == 1 ? Data.getU8(&Offset) : Data.getULEB128(&Offset);
244
245 // Parse the augmentation data for EH CIEs
246 StringRef AugmentationData("");
247 uint32_t FDEPointerEncoding = DW_EH_PE_absptr;
248 uint32_t LSDAPointerEncoding = DW_EH_PE_omit;
249 std::optional<uint64_t> Personality;
250 std::optional<uint32_t> PersonalityEncoding;
251 if (IsEH) {
252 std::optional<uint64_t> AugmentationLength;
253 uint64_t StartAugmentationOffset;
254 uint64_t EndAugmentationOffset;
255
256 // Walk the augmentation string to get all the augmentation data.
257 for (unsigned i = 0, e = AugmentationString.size(); i != e; ++i) {
258 switch (AugmentationString[i]) {
259 default:
260 return createStringError(
261 errc::invalid_argument,
262 "unknown augmentation character %c in entry at 0x%" PRIx64,
263 AugmentationString[i], StartOffset);
264 case 'L':
265 LSDAPointerEncoding = Data.getU8(&Offset);
266 break;
267 case 'P': {
268 if (Personality)
269 return createStringError(
270 errc::invalid_argument,
271 "duplicate personality in entry at 0x%" PRIx64, StartOffset);
272 PersonalityEncoding = Data.getU8(&Offset);
273 Personality = Data.getEncodedPointer(
274 &Offset, *PersonalityEncoding,
275 EHFrameAddress ? EHFrameAddress + Offset : 0);
276 break;
277 }
278 case 'R':
279 FDEPointerEncoding = Data.getU8(&Offset);
280 break;
281 case 'S':
282 // Current frame is a signal trampoline.
283 break;
284 case 'z':
285 if (i)
286 return createStringError(
287 errc::invalid_argument,
288 "'z' must be the first character at 0x%" PRIx64, StartOffset);
289 // Parse the augmentation length first. We only parse it if
290 // the string contains a 'z'.
291 AugmentationLength = Data.getULEB128(&Offset);
292 StartAugmentationOffset = Offset;
293 EndAugmentationOffset = Offset + *AugmentationLength;
294 break;
295 case 'B':
296 // B-Key is used for signing functions associated with this
297 // augmentation string
298 break;
299 // This stack frame contains MTE tagged data, so needs to be
300 // untagged on unwind.
301 case 'G':
302 break;
303 }
304 }
305
306 if (AugmentationLength) {
307 if (Offset != EndAugmentationOffset)
308 return createStringError(errc::invalid_argument,
309 "parsing augmentation data at 0x%" PRIx64
310 " failed",
311 StartOffset);
312 AugmentationData = Data.getData().slice(StartAugmentationOffset,
313 EndAugmentationOffset);
314 }
315 }
316
317 auto Cie = std::make_unique<CIE>(
318 IsDWARF64, StartOffset, Length, Version, AugmentationString,
319 AddressSize, SegmentDescriptorSize, CodeAlignmentFactor,
320 DataAlignmentFactor, ReturnAddressRegister, AugmentationData,
321 FDEPointerEncoding, LSDAPointerEncoding, Personality,
322 PersonalityEncoding, Arch);
323 CIEs[StartOffset] = Cie.get();
324 Entries.emplace_back(std::move(Cie));
325 } else {
326 // FDE
327 uint64_t CIEPointer = Id;
328 uint64_t InitialLocation = 0;
329 uint64_t AddressRange = 0;
330 std::optional<uint64_t> LSDAAddress;
331 CIE *Cie = CIEs[IsEH ? (StartStructureOffset - CIEPointer) : CIEPointer];
332
333 if (IsEH) {
334 // The address size is encoded in the CIE we reference.
335 if (!Cie)
336 return createStringError(errc::invalid_argument,
337 "parsing FDE data at 0x%" PRIx64
338 " failed due to missing CIE",
339 StartOffset);
340 if (auto Val =
341 Data.getEncodedPointer(&Offset, Cie->getFDEPointerEncoding(),
342 EHFrameAddress + Offset)) {
343 InitialLocation = *Val;
344 }
345 if (auto Val = Data.getEncodedPointer(
346 &Offset, Cie->getFDEPointerEncoding(), 0)) {
347 AddressRange = *Val;
348 }
349
350 StringRef AugmentationString = Cie->getAugmentationString();
351 if (!AugmentationString.empty()) {
352 // Parse the augmentation length and data for this FDE.
353 uint64_t AugmentationLength = Data.getULEB128(&Offset);
354
355 uint64_t EndAugmentationOffset = Offset + AugmentationLength;
356
357 // Decode the LSDA if the CIE augmentation string said we should.
358 if (Cie->getLSDAPointerEncoding() != DW_EH_PE_omit) {
359 LSDAAddress = Data.getEncodedPointer(
360 &Offset, Cie->getLSDAPointerEncoding(),
361 EHFrameAddress ? Offset + EHFrameAddress : 0);
362 }
363
364 if (Offset != EndAugmentationOffset)
365 return createStringError(errc::invalid_argument,
366 "parsing augmentation data at 0x%" PRIx64
367 " failed",
368 StartOffset);
369 }
370 } else {
371 InitialLocation = Data.getRelocatedAddress(&Offset);
372 AddressRange = Data.getRelocatedAddress(&Offset);
373 }
374
375 Entries.emplace_back(new FDE(IsDWARF64, StartOffset, Length, CIEPointer,
376 InitialLocation, AddressRange, Cie,
377 LSDAAddress, Arch));
378 }
379
380 if (Error E =
381 Entries.back()->cfis().parse(Data, &Offset, EndStructureOffset))
382 return E;
383
384 if (Offset != EndStructureOffset)
385 return createStringError(
386 errc::invalid_argument,
387 "parsing entry instructions at 0x%" PRIx64 " failed", StartOffset);
388 }
389
390 return Error::success();
391 }
392
getEntryAtOffset(uint64_t Offset) const393 FrameEntry *DWARFDebugFrame::getEntryAtOffset(uint64_t Offset) const {
394 auto It = partition_point(Entries, [=](const std::unique_ptr<FrameEntry> &E) {
395 return E->getOffset() < Offset;
396 });
397 if (It != Entries.end() && (*It)->getOffset() == Offset)
398 return It->get();
399 return nullptr;
400 }
401
dump(raw_ostream & OS,DIDumpOptions DumpOpts,std::optional<uint64_t> Offset) const402 void DWARFDebugFrame::dump(raw_ostream &OS, DIDumpOptions DumpOpts,
403 std::optional<uint64_t> Offset) const {
404 DumpOpts.IsEH = IsEH;
405 if (Offset) {
406 if (auto *Entry = getEntryAtOffset(*Offset))
407 Entry->dump(OS, DumpOpts);
408 return;
409 }
410
411 OS << "\n";
412 for (const auto &Entry : Entries)
413 Entry->dump(OS, DumpOpts);
414 }
415