1 | //===- ELFObjcopy.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/ObjCopy/ELF/ELFObjcopy.h" |
10 | #include "ELFObject.h" |
11 | #include "llvm/ADT/BitmaskEnum.h" |
12 | #include "llvm/ADT/DenseSet.h" |
13 | #include "llvm/ADT/SmallVector.h" |
14 | #include "llvm/ADT/StringRef.h" |
15 | #include "llvm/ADT/Twine.h" |
16 | #include "llvm/BinaryFormat/ELF.h" |
17 | #include "llvm/MC/MCTargetOptions.h" |
18 | #include "llvm/ObjCopy/CommonConfig.h" |
19 | #include "llvm/ObjCopy/ELF/ELFConfig.h" |
20 | #include "llvm/Object/Binary.h" |
21 | #include "llvm/Object/ELFObjectFile.h" |
22 | #include "llvm/Object/ELFTypes.h" |
23 | #include "llvm/Object/Error.h" |
24 | #include "llvm/Option/Option.h" |
25 | #include "llvm/Support/Casting.h" |
26 | #include "llvm/Support/Compression.h" |
27 | #include "llvm/Support/Errc.h" |
28 | #include "llvm/Support/Error.h" |
29 | #include "llvm/Support/ErrorHandling.h" |
30 | #include "llvm/Support/Memory.h" |
31 | #include "llvm/Support/raw_ostream.h" |
32 | #include <algorithm> |
33 | #include <cassert> |
34 | #include <cstdlib> |
35 | #include <functional> |
36 | #include <memory> |
37 | #include <string> |
38 | #include <system_error> |
39 | #include <utility> |
40 | |
41 | using namespace llvm; |
42 | using namespace llvm::ELF; |
43 | using namespace llvm::objcopy; |
44 | using namespace llvm::objcopy::elf; |
45 | using namespace llvm::object; |
46 | |
47 | using SectionPred = std::function<bool(const SectionBase &Sec)>; |
48 | |
49 | static bool isDebugSection(const SectionBase &Sec) { |
50 | return StringRef(Sec.Name).starts_with(Prefix: ".debug" ) || Sec.Name == ".gdb_index" ; |
51 | } |
52 | |
53 | static bool isDWOSection(const SectionBase &Sec) { |
54 | return StringRef(Sec.Name).ends_with(Suffix: ".dwo" ); |
55 | } |
56 | |
57 | static bool onlyKeepDWOPred(const Object &Obj, const SectionBase &Sec) { |
58 | // We can't remove the section header string table. |
59 | if (&Sec == Obj.SectionNames) |
60 | return false; |
61 | // Short of keeping the string table we want to keep everything that is a DWO |
62 | // section and remove everything else. |
63 | return !isDWOSection(Sec); |
64 | } |
65 | |
66 | static Expected<uint64_t> getNewShfFlags(SectionFlag AllFlags, |
67 | uint16_t EMachine) { |
68 | uint64_t NewFlags = 0; |
69 | if (AllFlags & SectionFlag::SecAlloc) |
70 | NewFlags |= ELF::SHF_ALLOC; |
71 | if (!(AllFlags & SectionFlag::SecReadonly)) |
72 | NewFlags |= ELF::SHF_WRITE; |
73 | if (AllFlags & SectionFlag::SecCode) |
74 | NewFlags |= ELF::SHF_EXECINSTR; |
75 | if (AllFlags & SectionFlag::SecMerge) |
76 | NewFlags |= ELF::SHF_MERGE; |
77 | if (AllFlags & SectionFlag::SecStrings) |
78 | NewFlags |= ELF::SHF_STRINGS; |
79 | if (AllFlags & SectionFlag::SecExclude) |
80 | NewFlags |= ELF::SHF_EXCLUDE; |
81 | if (AllFlags & SectionFlag::SecLarge) { |
82 | if (EMachine != EM_X86_64) |
83 | return createStringError(EC: errc::invalid_argument, |
84 | S: "section flag SHF_X86_64_LARGE can only be used " |
85 | "with x86_64 architecture" ); |
86 | NewFlags |= ELF::SHF_X86_64_LARGE; |
87 | } |
88 | return NewFlags; |
89 | } |
90 | |
91 | static uint64_t getSectionFlagsPreserveMask(uint64_t OldFlags, |
92 | uint64_t NewFlags, |
93 | uint16_t EMachine) { |
94 | // Preserve some flags which should not be dropped when setting flags. |
95 | // Also, preserve anything OS/processor dependant. |
96 | const uint64_t PreserveMask = |
97 | (ELF::SHF_COMPRESSED | ELF::SHF_GROUP | ELF::SHF_LINK_ORDER | |
98 | ELF::SHF_MASKOS | ELF::SHF_MASKPROC | ELF::SHF_TLS | |
99 | ELF::SHF_INFO_LINK) & |
100 | ~ELF::SHF_EXCLUDE & |
101 | ~(EMachine == EM_X86_64 ? (uint64_t)ELF::SHF_X86_64_LARGE : 0UL); |
102 | return (OldFlags & PreserveMask) | (NewFlags & ~PreserveMask); |
103 | } |
104 | |
105 | static void setSectionType(SectionBase &Sec, uint64_t Type) { |
106 | // If Sec's type is changed from SHT_NOBITS due to --set-section-flags, |
107 | // Offset may not be aligned. Align it to max(Align, 1). |
108 | if (Sec.Type == ELF::SHT_NOBITS && Type != ELF::SHT_NOBITS) |
109 | Sec.Offset = alignTo(Value: Sec.Offset, Align: std::max(a: Sec.Align, b: uint64_t(1))); |
110 | Sec.Type = Type; |
111 | } |
112 | |
113 | static Error setSectionFlagsAndType(SectionBase &Sec, SectionFlag Flags, |
114 | uint16_t EMachine) { |
115 | Expected<uint64_t> NewFlags = getNewShfFlags(AllFlags: Flags, EMachine); |
116 | if (!NewFlags) |
117 | return NewFlags.takeError(); |
118 | Sec.Flags = getSectionFlagsPreserveMask(OldFlags: Sec.Flags, NewFlags: *NewFlags, EMachine); |
119 | |
120 | // In GNU objcopy, certain flags promote SHT_NOBITS to SHT_PROGBITS. This rule |
121 | // may promote more non-ALLOC sections than GNU objcopy, but it is fine as |
122 | // non-ALLOC SHT_NOBITS sections do not make much sense. |
123 | if (Sec.Type == SHT_NOBITS && |
124 | (!(Sec.Flags & ELF::SHF_ALLOC) || |
125 | Flags & (SectionFlag::SecContents | SectionFlag::SecLoad))) |
126 | setSectionType(Sec, Type: ELF::SHT_PROGBITS); |
127 | |
128 | return Error::success(); |
129 | } |
130 | |
131 | static ElfType getOutputElfType(const Binary &Bin) { |
132 | // Infer output ELF type from the input ELF object |
133 | if (isa<ELFObjectFile<ELF32LE>>(Val: Bin)) |
134 | return ELFT_ELF32LE; |
135 | if (isa<ELFObjectFile<ELF64LE>>(Val: Bin)) |
136 | return ELFT_ELF64LE; |
137 | if (isa<ELFObjectFile<ELF32BE>>(Val: Bin)) |
138 | return ELFT_ELF32BE; |
139 | if (isa<ELFObjectFile<ELF64BE>>(Val: Bin)) |
140 | return ELFT_ELF64BE; |
141 | llvm_unreachable("Invalid ELFType" ); |
142 | } |
143 | |
144 | static ElfType getOutputElfType(const MachineInfo &MI) { |
145 | // Infer output ELF type from the binary arch specified |
146 | if (MI.Is64Bit) |
147 | return MI.IsLittleEndian ? ELFT_ELF64LE : ELFT_ELF64BE; |
148 | else |
149 | return MI.IsLittleEndian ? ELFT_ELF32LE : ELFT_ELF32BE; |
150 | } |
151 | |
152 | static std::unique_ptr<Writer> createELFWriter(const CommonConfig &Config, |
153 | Object &Obj, raw_ostream &Out, |
154 | ElfType OutputElfType) { |
155 | // Depending on the initial ELFT and OutputFormat we need a different Writer. |
156 | switch (OutputElfType) { |
157 | case ELFT_ELF32LE: |
158 | return std::make_unique<ELFWriter<ELF32LE>>(args&: Obj, args&: Out, args: !Config.StripSections, |
159 | args: Config.OnlyKeepDebug); |
160 | case ELFT_ELF64LE: |
161 | return std::make_unique<ELFWriter<ELF64LE>>(args&: Obj, args&: Out, args: !Config.StripSections, |
162 | args: Config.OnlyKeepDebug); |
163 | case ELFT_ELF32BE: |
164 | return std::make_unique<ELFWriter<ELF32BE>>(args&: Obj, args&: Out, args: !Config.StripSections, |
165 | args: Config.OnlyKeepDebug); |
166 | case ELFT_ELF64BE: |
167 | return std::make_unique<ELFWriter<ELF64BE>>(args&: Obj, args&: Out, args: !Config.StripSections, |
168 | args: Config.OnlyKeepDebug); |
169 | } |
170 | llvm_unreachable("Invalid output format" ); |
171 | } |
172 | |
173 | static std::unique_ptr<Writer> createWriter(const CommonConfig &Config, |
174 | Object &Obj, raw_ostream &Out, |
175 | ElfType OutputElfType) { |
176 | switch (Config.OutputFormat) { |
177 | case FileFormat::Binary: |
178 | return std::make_unique<BinaryWriter>(args&: Obj, args&: Out, args: Config); |
179 | case FileFormat::IHex: |
180 | return std::make_unique<IHexWriter>(args&: Obj, args&: Out, args: Config.OutputFilename); |
181 | case FileFormat::SREC: |
182 | return std::make_unique<SRECWriter>(args&: Obj, args&: Out, args: Config.OutputFilename); |
183 | default: |
184 | return createELFWriter(Config, Obj, Out, OutputElfType); |
185 | } |
186 | } |
187 | |
188 | static Error dumpSectionToFile(StringRef SecName, StringRef Filename, |
189 | StringRef InputFilename, Object &Obj) { |
190 | for (auto &Sec : Obj.sections()) { |
191 | if (Sec.Name == SecName) { |
192 | if (Sec.Type == SHT_NOBITS) |
193 | return createFileError(F: InputFilename, EC: object_error::parse_failed, |
194 | Fmt: "cannot dump section '%s': it has no contents" , |
195 | Vals: SecName.str().c_str()); |
196 | Expected<std::unique_ptr<FileOutputBuffer>> BufferOrErr = |
197 | FileOutputBuffer::create(FilePath: Filename, Size: Sec.OriginalData.size()); |
198 | if (!BufferOrErr) |
199 | return createFileError(F: Filename, E: BufferOrErr.takeError()); |
200 | std::unique_ptr<FileOutputBuffer> Buf = std::move(*BufferOrErr); |
201 | std::copy(first: Sec.OriginalData.begin(), last: Sec.OriginalData.end(), |
202 | result: Buf->getBufferStart()); |
203 | if (Error E = Buf->commit()) |
204 | return createFileError(F: Filename, E: std::move(E)); |
205 | return Error::success(); |
206 | } |
207 | } |
208 | |
209 | return createFileError(F: InputFilename, EC: object_error::parse_failed, |
210 | Fmt: "section '%s' not found" , Vals: SecName.str().c_str()); |
211 | } |
212 | |
213 | Error Object::compressOrDecompressSections(const CommonConfig &Config) { |
214 | // Build a list of sections we are going to replace. |
215 | // We can't call `addSection` while iterating over sections, |
216 | // because it would mutate the sections array. |
217 | SmallVector<std::pair<SectionBase *, std::function<SectionBase *()>>, 0> |
218 | ToReplace; |
219 | for (SectionBase &Sec : sections()) { |
220 | std::optional<DebugCompressionType> CType; |
221 | for (auto &[Matcher, T] : Config.compressSections) |
222 | if (Matcher.matches(S: Sec.Name)) |
223 | CType = T; |
224 | // Handle --compress-debug-sections and --decompress-debug-sections, which |
225 | // apply to non-ALLOC debug sections. |
226 | if (!(Sec.Flags & SHF_ALLOC) && StringRef(Sec.Name).starts_with(Prefix: ".debug" )) { |
227 | if (Config.CompressionType != DebugCompressionType::None) |
228 | CType = Config.CompressionType; |
229 | else if (Config.DecompressDebugSections) |
230 | CType = DebugCompressionType::None; |
231 | } |
232 | if (!CType) |
233 | continue; |
234 | |
235 | if (Sec.ParentSegment) |
236 | return createStringError( |
237 | EC: errc::invalid_argument, |
238 | S: "section '" + Sec.Name + |
239 | "' within a segment cannot be (de)compressed" ); |
240 | |
241 | if (auto *CS = dyn_cast<CompressedSection>(Val: &Sec)) { |
242 | if (*CType == DebugCompressionType::None) |
243 | ToReplace.emplace_back( |
244 | Args: &Sec, Args: [=] { return &addSection<DecompressedSection>(Args&: *CS); }); |
245 | } else if (*CType != DebugCompressionType::None) { |
246 | ToReplace.emplace_back(Args: &Sec, Args: [=, S = &Sec] { |
247 | return &addSection<CompressedSection>( |
248 | Args: CompressedSection(*S, *CType, Is64Bits)); |
249 | }); |
250 | } |
251 | } |
252 | |
253 | DenseMap<SectionBase *, SectionBase *> FromTo; |
254 | for (auto [S, Func] : ToReplace) |
255 | FromTo[S] = Func(); |
256 | return replaceSections(FromTo); |
257 | } |
258 | |
259 | static bool isAArch64MappingSymbol(const Symbol &Sym) { |
260 | if (Sym.Binding != STB_LOCAL || Sym.Type != STT_NOTYPE || |
261 | Sym.getShndx() == SHN_UNDEF) |
262 | return false; |
263 | StringRef Name = Sym.Name; |
264 | if (!Name.consume_front(Prefix: "$x" ) && !Name.consume_front(Prefix: "$d" )) |
265 | return false; |
266 | return Name.empty() || Name.starts_with(Prefix: "." ); |
267 | } |
268 | |
269 | static bool isArmMappingSymbol(const Symbol &Sym) { |
270 | if (Sym.Binding != STB_LOCAL || Sym.Type != STT_NOTYPE || |
271 | Sym.getShndx() == SHN_UNDEF) |
272 | return false; |
273 | StringRef Name = Sym.Name; |
274 | if (!Name.consume_front(Prefix: "$a" ) && !Name.consume_front(Prefix: "$d" ) && |
275 | !Name.consume_front(Prefix: "$t" )) |
276 | return false; |
277 | return Name.empty() || Name.starts_with(Prefix: "." ); |
278 | } |
279 | |
280 | // Check if the symbol should be preserved because it is required by ABI. |
281 | static bool isRequiredByABISymbol(const Object &Obj, const Symbol &Sym) { |
282 | switch (Obj.Machine) { |
283 | case EM_AARCH64: |
284 | // Mapping symbols should be preserved for a relocatable object file. |
285 | return Obj.isRelocatable() && isAArch64MappingSymbol(Sym); |
286 | case EM_ARM: |
287 | // Mapping symbols should be preserved for a relocatable object file. |
288 | return Obj.isRelocatable() && isArmMappingSymbol(Sym); |
289 | default: |
290 | return false; |
291 | } |
292 | } |
293 | |
294 | static bool isUnneededSymbol(const Symbol &Sym) { |
295 | return !Sym.Referenced && |
296 | (Sym.Binding == STB_LOCAL || Sym.getShndx() == SHN_UNDEF) && |
297 | Sym.Type != STT_SECTION; |
298 | } |
299 | |
300 | static Error updateAndRemoveSymbols(const CommonConfig &Config, |
301 | const ELFConfig &ELFConfig, Object &Obj) { |
302 | // TODO: update or remove symbols only if there is an option that affects |
303 | // them. |
304 | if (!Obj.SymbolTable) |
305 | return Error::success(); |
306 | |
307 | Obj.SymbolTable->updateSymbols(Callable: [&](Symbol &Sym) { |
308 | if (Config.SymbolsToSkip.matches(S: Sym.Name)) |
309 | return; |
310 | |
311 | // Common and undefined symbols don't make sense as local symbols, and can |
312 | // even cause crashes if we localize those, so skip them. |
313 | if (!Sym.isCommon() && Sym.getShndx() != SHN_UNDEF && |
314 | ((ELFConfig.LocalizeHidden && |
315 | (Sym.Visibility == STV_HIDDEN || Sym.Visibility == STV_INTERNAL)) || |
316 | Config.SymbolsToLocalize.matches(S: Sym.Name))) |
317 | Sym.Binding = STB_LOCAL; |
318 | |
319 | for (auto &[Matcher, Visibility] : ELFConfig.SymbolsToSetVisibility) |
320 | if (Matcher.matches(S: Sym.Name)) |
321 | Sym.Visibility = Visibility; |
322 | |
323 | // Note: these two globalize flags have very similar names but different |
324 | // meanings: |
325 | // |
326 | // --globalize-symbol: promote a symbol to global |
327 | // --keep-global-symbol: all symbols except for these should be made local |
328 | // |
329 | // If --globalize-symbol is specified for a given symbol, it will be |
330 | // global in the output file even if it is not included via |
331 | // --keep-global-symbol. Because of that, make sure to check |
332 | // --globalize-symbol second. |
333 | if (!Config.SymbolsToKeepGlobal.empty() && |
334 | !Config.SymbolsToKeepGlobal.matches(S: Sym.Name) && |
335 | Sym.getShndx() != SHN_UNDEF) |
336 | Sym.Binding = STB_LOCAL; |
337 | |
338 | if (Config.SymbolsToGlobalize.matches(S: Sym.Name) && |
339 | Sym.getShndx() != SHN_UNDEF) |
340 | Sym.Binding = STB_GLOBAL; |
341 | |
342 | // SymbolsToWeaken applies to both STB_GLOBAL and STB_GNU_UNIQUE. |
343 | if (Config.SymbolsToWeaken.matches(S: Sym.Name) && Sym.Binding != STB_LOCAL) |
344 | Sym.Binding = STB_WEAK; |
345 | |
346 | if (Config.Weaken && Sym.Binding != STB_LOCAL && |
347 | Sym.getShndx() != SHN_UNDEF) |
348 | Sym.Binding = STB_WEAK; |
349 | |
350 | const auto I = Config.SymbolsToRename.find(Key: Sym.Name); |
351 | if (I != Config.SymbolsToRename.end()) |
352 | Sym.Name = std::string(I->getValue()); |
353 | |
354 | if (!Config.SymbolsPrefixRemove.empty() && Sym.Type != STT_SECTION) |
355 | if (StringRef(Sym.Name).starts_with(Prefix: Config.SymbolsPrefixRemove)) |
356 | Sym.Name = Sym.Name.substr(pos: Config.SymbolsPrefixRemove.size()); |
357 | |
358 | if (!Config.SymbolsPrefix.empty() && Sym.Type != STT_SECTION) |
359 | Sym.Name = (Config.SymbolsPrefix + Sym.Name).str(); |
360 | }); |
361 | |
362 | // The purpose of this loop is to mark symbols referenced by sections |
363 | // (like GroupSection or RelocationSection). This way, we know which |
364 | // symbols are still 'needed' and which are not. |
365 | if (Config.StripUnneeded || !Config.UnneededSymbolsToRemove.empty() || |
366 | !Config.OnlySection.empty() || Config.DiscardMode != DiscardType::None) { |
367 | for (SectionBase &Sec : Obj.sections()) |
368 | Sec.markSymbols(); |
369 | } |
370 | |
371 | auto RemoveSymbolsPred = [&](const Symbol &Sym) { |
372 | if (Config.SymbolsToKeep.matches(S: Sym.Name) || |
373 | (ELFConfig.KeepFileSymbols && Sym.Type == STT_FILE)) |
374 | return false; |
375 | |
376 | if (Config.SymbolsToRemove.matches(S: Sym.Name)) |
377 | return true; |
378 | |
379 | if (Config.StripAll || Config.StripAllGNU) |
380 | return true; |
381 | |
382 | if (isRequiredByABISymbol(Obj, Sym)) |
383 | return false; |
384 | |
385 | if (Config.StripDebug && Sym.Type == STT_FILE) |
386 | return true; |
387 | |
388 | if ((Config.StripUnneeded || |
389 | Config.UnneededSymbolsToRemove.matches(S: Sym.Name)) && |
390 | (!Obj.isRelocatable() || isUnneededSymbol(Sym))) |
391 | return true; |
392 | |
393 | if (!Sym.Referenced) { |
394 | if ((Config.DiscardMode == DiscardType::All || |
395 | (Config.DiscardMode == DiscardType::Locals && |
396 | StringRef(Sym.Name).starts_with(Prefix: ".L" ))) && |
397 | Sym.Binding == STB_LOCAL && Sym.getShndx() != SHN_UNDEF && |
398 | Sym.Type != STT_FILE && Sym.Type != STT_SECTION) |
399 | return true; |
400 | // We want to remove undefined symbols if all references have been |
401 | // stripped. |
402 | if (!Config.OnlySection.empty() && Sym.getShndx() == SHN_UNDEF) |
403 | return true; |
404 | } |
405 | |
406 | return false; |
407 | }; |
408 | |
409 | return Obj.removeSymbols(ToRemove: RemoveSymbolsPred); |
410 | } |
411 | |
412 | static Error replaceAndRemoveSections(const CommonConfig &Config, |
413 | const ELFConfig &ELFConfig, Object &Obj) { |
414 | SectionPred RemovePred = [](const SectionBase &) { return false; }; |
415 | |
416 | // Removes: |
417 | if (!Config.ToRemove.empty()) { |
418 | RemovePred = [&Config](const SectionBase &Sec) { |
419 | return Config.ToRemove.matches(S: Sec.Name); |
420 | }; |
421 | } |
422 | |
423 | if (Config.StripDWO) |
424 | RemovePred = [RemovePred](const SectionBase &Sec) { |
425 | return isDWOSection(Sec) || RemovePred(Sec); |
426 | }; |
427 | |
428 | if (Config.ExtractDWO) |
429 | RemovePred = [RemovePred, &Obj](const SectionBase &Sec) { |
430 | return onlyKeepDWOPred(Obj, Sec) || RemovePred(Sec); |
431 | }; |
432 | |
433 | if (Config.StripAllGNU) |
434 | RemovePred = [RemovePred, &Obj](const SectionBase &Sec) { |
435 | if (RemovePred(Sec)) |
436 | return true; |
437 | if ((Sec.Flags & SHF_ALLOC) != 0) |
438 | return false; |
439 | if (&Sec == Obj.SectionNames) |
440 | return false; |
441 | switch (Sec.Type) { |
442 | case SHT_SYMTAB: |
443 | case SHT_REL: |
444 | case SHT_RELA: |
445 | case SHT_STRTAB: |
446 | return true; |
447 | } |
448 | return isDebugSection(Sec); |
449 | }; |
450 | |
451 | if (Config.StripSections) { |
452 | RemovePred = [RemovePred](const SectionBase &Sec) { |
453 | return RemovePred(Sec) || Sec.ParentSegment == nullptr; |
454 | }; |
455 | } |
456 | |
457 | if (Config.StripDebug || Config.StripUnneeded) { |
458 | RemovePred = [RemovePred](const SectionBase &Sec) { |
459 | return RemovePred(Sec) || isDebugSection(Sec); |
460 | }; |
461 | } |
462 | |
463 | if (Config.StripNonAlloc) |
464 | RemovePred = [RemovePred, &Obj](const SectionBase &Sec) { |
465 | if (RemovePred(Sec)) |
466 | return true; |
467 | if (&Sec == Obj.SectionNames) |
468 | return false; |
469 | return (Sec.Flags & SHF_ALLOC) == 0 && Sec.ParentSegment == nullptr; |
470 | }; |
471 | |
472 | if (Config.StripAll) |
473 | RemovePred = [RemovePred, &Obj](const SectionBase &Sec) { |
474 | if (RemovePred(Sec)) |
475 | return true; |
476 | if (&Sec == Obj.SectionNames) |
477 | return false; |
478 | if (StringRef(Sec.Name).starts_with(Prefix: ".gnu.warning" )) |
479 | return false; |
480 | if (StringRef(Sec.Name).starts_with(Prefix: ".gnu_debuglink" )) |
481 | return false; |
482 | // We keep the .ARM.attribute section to maintain compatibility |
483 | // with Debian derived distributions. This is a bug in their |
484 | // patchset as documented here: |
485 | // https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=943798 |
486 | if (Sec.Type == SHT_ARM_ATTRIBUTES) |
487 | return false; |
488 | if (Sec.ParentSegment != nullptr) |
489 | return false; |
490 | return (Sec.Flags & SHF_ALLOC) == 0; |
491 | }; |
492 | |
493 | if (Config.ExtractPartition || Config.ExtractMainPartition) { |
494 | RemovePred = [RemovePred](const SectionBase &Sec) { |
495 | if (RemovePred(Sec)) |
496 | return true; |
497 | if (Sec.Type == SHT_LLVM_PART_EHDR || Sec.Type == SHT_LLVM_PART_PHDR) |
498 | return true; |
499 | return (Sec.Flags & SHF_ALLOC) != 0 && !Sec.ParentSegment; |
500 | }; |
501 | } |
502 | |
503 | // Explicit copies: |
504 | if (!Config.OnlySection.empty()) { |
505 | RemovePred = [&Config, RemovePred, &Obj](const SectionBase &Sec) { |
506 | // Explicitly keep these sections regardless of previous removes. |
507 | if (Config.OnlySection.matches(S: Sec.Name)) |
508 | return false; |
509 | |
510 | // Allow all implicit removes. |
511 | if (RemovePred(Sec)) |
512 | return true; |
513 | |
514 | // Keep special sections. |
515 | if (Obj.SectionNames == &Sec) |
516 | return false; |
517 | if (Obj.SymbolTable == &Sec || |
518 | (Obj.SymbolTable && Obj.SymbolTable->getStrTab() == &Sec)) |
519 | return false; |
520 | |
521 | // Remove everything else. |
522 | return true; |
523 | }; |
524 | } |
525 | |
526 | if (!Config.KeepSection.empty()) { |
527 | RemovePred = [&Config, RemovePred](const SectionBase &Sec) { |
528 | // Explicitly keep these sections regardless of previous removes. |
529 | if (Config.KeepSection.matches(S: Sec.Name)) |
530 | return false; |
531 | // Otherwise defer to RemovePred. |
532 | return RemovePred(Sec); |
533 | }; |
534 | } |
535 | |
536 | // This has to be the last predicate assignment. |
537 | // If the option --keep-symbol has been specified |
538 | // and at least one of those symbols is present |
539 | // (equivalently, the updated symbol table is not empty) |
540 | // the symbol table and the string table should not be removed. |
541 | if ((!Config.SymbolsToKeep.empty() || ELFConfig.KeepFileSymbols) && |
542 | Obj.SymbolTable && !Obj.SymbolTable->empty()) { |
543 | RemovePred = [&Obj, RemovePred](const SectionBase &Sec) { |
544 | if (&Sec == Obj.SymbolTable || &Sec == Obj.SymbolTable->getStrTab()) |
545 | return false; |
546 | return RemovePred(Sec); |
547 | }; |
548 | } |
549 | |
550 | if (Error E = Obj.removeSections(AllowBrokenLinks: ELFConfig.AllowBrokenLinks, ToRemove: RemovePred)) |
551 | return E; |
552 | |
553 | if (Error E = Obj.compressOrDecompressSections(Config)) |
554 | return E; |
555 | |
556 | return Error::success(); |
557 | } |
558 | |
559 | // Add symbol to the Object symbol table with the specified properties. |
560 | static void addSymbol(Object &Obj, const NewSymbolInfo &SymInfo, |
561 | uint8_t DefaultVisibility) { |
562 | SectionBase *Sec = Obj.findSection(Name: SymInfo.SectionName); |
563 | uint64_t Value = Sec ? Sec->Addr + SymInfo.Value : SymInfo.Value; |
564 | |
565 | uint8_t Bind = ELF::STB_GLOBAL; |
566 | uint8_t Type = ELF::STT_NOTYPE; |
567 | uint8_t Visibility = DefaultVisibility; |
568 | |
569 | for (SymbolFlag FlagValue : SymInfo.Flags) |
570 | switch (FlagValue) { |
571 | case SymbolFlag::Global: |
572 | Bind = ELF::STB_GLOBAL; |
573 | break; |
574 | case SymbolFlag::Local: |
575 | Bind = ELF::STB_LOCAL; |
576 | break; |
577 | case SymbolFlag::Weak: |
578 | Bind = ELF::STB_WEAK; |
579 | break; |
580 | case SymbolFlag::Default: |
581 | Visibility = ELF::STV_DEFAULT; |
582 | break; |
583 | case SymbolFlag::Hidden: |
584 | Visibility = ELF::STV_HIDDEN; |
585 | break; |
586 | case SymbolFlag::Protected: |
587 | Visibility = ELF::STV_PROTECTED; |
588 | break; |
589 | case SymbolFlag::File: |
590 | Type = ELF::STT_FILE; |
591 | break; |
592 | case SymbolFlag::Section: |
593 | Type = ELF::STT_SECTION; |
594 | break; |
595 | case SymbolFlag::Object: |
596 | Type = ELF::STT_OBJECT; |
597 | break; |
598 | case SymbolFlag::Function: |
599 | Type = ELF::STT_FUNC; |
600 | break; |
601 | case SymbolFlag::IndirectFunction: |
602 | Type = ELF::STT_GNU_IFUNC; |
603 | break; |
604 | default: /* Other flag values are ignored for ELF. */ |
605 | break; |
606 | }; |
607 | |
608 | Obj.SymbolTable->addSymbol( |
609 | Name: SymInfo.SymbolName, Bind, Type, DefinedIn: Sec, Value, Visibility, |
610 | Shndx: Sec ? (uint16_t)SYMBOL_SIMPLE_INDEX : (uint16_t)SHN_ABS, SymbolSize: 0); |
611 | } |
612 | |
613 | namespace { |
614 | struct RemoveNoteDetail { |
615 | struct DeletedRange { |
616 | uint64_t OldFrom; |
617 | uint64_t OldTo; |
618 | }; |
619 | |
620 | template <class ELFT> |
621 | static std::vector<DeletedRange> |
622 | findNotesToRemove(ArrayRef<uint8_t> Data, size_t Align, |
623 | ArrayRef<RemoveNoteInfo> NotesToRemove); |
624 | static std::vector<uint8_t> updateData(ArrayRef<uint8_t> OldData, |
625 | ArrayRef<DeletedRange> ToRemove); |
626 | }; |
627 | } // namespace |
628 | |
629 | template <class ELFT> |
630 | std::vector<RemoveNoteDetail::DeletedRange> |
631 | RemoveNoteDetail::findNotesToRemove(ArrayRef<uint8_t> Data, size_t Align, |
632 | ArrayRef<RemoveNoteInfo> NotesToRemove) { |
633 | using Elf_Nhdr = typename ELFT::Nhdr; |
634 | using Elf_Note = typename ELFT::Note; |
635 | std::vector<DeletedRange> ToRemove; |
636 | uint64_t CurPos = 0; |
637 | while (CurPos + sizeof(Elf_Nhdr) <= Data.size()) { |
638 | auto Nhdr = reinterpret_cast<const Elf_Nhdr *>(Data.data() + CurPos); |
639 | size_t FullSize = Nhdr->getSize(Align); |
640 | if (CurPos + FullSize > Data.size()) |
641 | break; |
642 | Elf_Note Note(*Nhdr); |
643 | bool ShouldRemove = |
644 | llvm::any_of(NotesToRemove, [&Note](const RemoveNoteInfo &NoteInfo) { |
645 | return NoteInfo.TypeId == Note.getType() && |
646 | (NoteInfo.Name.empty() || NoteInfo.Name == Note.getName()); |
647 | }); |
648 | if (ShouldRemove) |
649 | ToRemove.push_back(x: {.OldFrom: CurPos, .OldTo: CurPos + FullSize}); |
650 | CurPos += FullSize; |
651 | } |
652 | return ToRemove; |
653 | } |
654 | |
655 | std::vector<uint8_t> |
656 | RemoveNoteDetail::updateData(ArrayRef<uint8_t> OldData, |
657 | ArrayRef<DeletedRange> ToRemove) { |
658 | std::vector<uint8_t> NewData; |
659 | NewData.reserve(n: OldData.size()); |
660 | uint64_t CurPos = 0; |
661 | for (const DeletedRange &RemRange : ToRemove) { |
662 | if (CurPos < RemRange.OldFrom) { |
663 | auto Slice = OldData.slice(N: CurPos, M: RemRange.OldFrom - CurPos); |
664 | llvm::append_range(C&: NewData, R&: Slice); |
665 | } |
666 | CurPos = RemRange.OldTo; |
667 | } |
668 | if (CurPos < OldData.size()) { |
669 | auto Slice = OldData.slice(N: CurPos); |
670 | llvm::append_range(C&: NewData, R&: Slice); |
671 | } |
672 | return NewData; |
673 | } |
674 | |
675 | static Error removeNotes(Object &Obj, endianness Endianness, |
676 | ArrayRef<RemoveNoteInfo> NotesToRemove, |
677 | function_ref<Error(Error)> ErrorCallback) { |
678 | // TODO: Support note segments. |
679 | if (ErrorCallback) { |
680 | for (Segment &Seg : Obj.segments()) { |
681 | if (Seg.Type == PT_NOTE) { |
682 | if (Error E = ErrorCallback(createStringError( |
683 | EC: errc::not_supported, S: "note segments are not supported" ))) |
684 | return E; |
685 | break; |
686 | } |
687 | } |
688 | } |
689 | for (auto &Sec : Obj.sections()) { |
690 | if (Sec.Type != SHT_NOTE || !Sec.hasContents()) |
691 | continue; |
692 | // TODO: Support note sections in segments. |
693 | if (Sec.ParentSegment) { |
694 | if (ErrorCallback) |
695 | if (Error E = ErrorCallback(createStringError( |
696 | EC: errc::not_supported, |
697 | S: "cannot remove note(s) from " + Sec.Name + |
698 | ": sections in segments are not supported" ))) |
699 | return E; |
700 | continue; |
701 | } |
702 | ArrayRef<uint8_t> OldData = Sec.getContents(); |
703 | size_t Align = std::max<size_t>(a: 4, b: Sec.Align); |
704 | // Note: notes for both 32-bit and 64-bit ELF files use 4-byte words in the |
705 | // header, so the parsers are the same. |
706 | auto ToRemove = (Endianness == endianness::little) |
707 | ? RemoveNoteDetail::findNotesToRemove<ELF64LE>( |
708 | Data: OldData, Align, NotesToRemove) |
709 | : RemoveNoteDetail::findNotesToRemove<ELF64BE>( |
710 | Data: OldData, Align, NotesToRemove); |
711 | if (!ToRemove.empty()) { |
712 | if (Error E = Obj.updateSectionData( |
713 | S&: Sec, Data: RemoveNoteDetail::updateData(OldData, ToRemove))) |
714 | return E; |
715 | } |
716 | } |
717 | return Error::success(); |
718 | } |
719 | |
720 | static Error |
721 | handleUserSection(const NewSectionInfo &NewSection, |
722 | function_ref<Error(StringRef, ArrayRef<uint8_t>)> F) { |
723 | ArrayRef<uint8_t> Data(reinterpret_cast<const uint8_t *>( |
724 | NewSection.SectionData->getBufferStart()), |
725 | NewSection.SectionData->getBufferSize()); |
726 | return F(NewSection.SectionName, Data); |
727 | } |
728 | |
729 | static Error verifyNoteSection(StringRef Name, endianness Endianness, |
730 | ArrayRef<uint8_t> Data) { |
731 | // An ELF note has the following structure: |
732 | // Name Size: 4 bytes (integer) |
733 | // Desc Size: 4 bytes (integer) |
734 | // Type : 4 bytes |
735 | // Name : variable size, padded to a 4 byte boundary |
736 | // Desc : variable size, padded to a 4 byte boundary |
737 | |
738 | if (Data.empty()) |
739 | return Error::success(); |
740 | |
741 | if (Data.size() < 12) { |
742 | std::string msg; |
743 | raw_string_ostream(msg) |
744 | << Name << " data must be either empty or at least 12 bytes long" ; |
745 | return createStringError(EC: errc::invalid_argument, S: msg); |
746 | } |
747 | if (Data.size() % 4 != 0) { |
748 | std::string msg; |
749 | raw_string_ostream(msg) |
750 | << Name << " data size must be a multiple of 4 bytes" ; |
751 | return createStringError(EC: errc::invalid_argument, S: msg); |
752 | } |
753 | ArrayRef<uint8_t> NameSize = Data.slice(N: 0, M: 4); |
754 | ArrayRef<uint8_t> DescSize = Data.slice(N: 4, M: 4); |
755 | |
756 | uint32_t NameSizeValue = support::endian::read32(P: NameSize.data(), E: Endianness); |
757 | uint32_t DescSizeValue = support::endian::read32(P: DescSize.data(), E: Endianness); |
758 | |
759 | uint64_t ExpectedDataSize = |
760 | /*NameSize=*/4 + /*DescSize=*/4 + /*Type=*/4 + |
761 | /*Name=*/alignTo(Value: NameSizeValue, Align: 4) + |
762 | /*Desc=*/alignTo(Value: DescSizeValue, Align: 4); |
763 | uint64_t ActualDataSize = Data.size(); |
764 | if (ActualDataSize != ExpectedDataSize) { |
765 | std::string msg; |
766 | raw_string_ostream(msg) |
767 | << Name |
768 | << " data size is incompatible with the content of " |
769 | "the name and description size fields:" |
770 | << " expecting " << ExpectedDataSize << ", found " << ActualDataSize; |
771 | return createStringError(EC: errc::invalid_argument, S: msg); |
772 | } |
773 | |
774 | return Error::success(); |
775 | } |
776 | |
777 | // This function handles the high level operations of GNU objcopy including |
778 | // handling command line options. It's important to outline certain properties |
779 | // we expect to hold of the command line operations. Any operation that "keeps" |
780 | // should keep regardless of a remove. Additionally any removal should respect |
781 | // any previous removals. Lastly whether or not something is removed shouldn't |
782 | // depend a) on the order the options occur in or b) on some opaque priority |
783 | // system. The only priority is that keeps/copies overrule removes. |
784 | static Error handleArgs(const CommonConfig &Config, const ELFConfig &ELFConfig, |
785 | ElfType OutputElfType, Object &Obj) { |
786 | if (Config.OutputArch) { |
787 | Obj.Machine = Config.OutputArch->EMachine; |
788 | Obj.OSABI = Config.OutputArch->OSABI; |
789 | } |
790 | |
791 | if (!Config.SplitDWO.empty() && Config.ExtractDWO) { |
792 | return Obj.removeSections( |
793 | AllowBrokenLinks: ELFConfig.AllowBrokenLinks, |
794 | ToRemove: [&Obj](const SectionBase &Sec) { return onlyKeepDWOPred(Obj, Sec); }); |
795 | } |
796 | |
797 | // Dump sections before add/remove for compatibility with GNU objcopy. |
798 | for (StringRef Flag : Config.DumpSection) { |
799 | StringRef SectionName; |
800 | StringRef FileName; |
801 | std::tie(args&: SectionName, args&: FileName) = Flag.split(Separator: '='); |
802 | if (Error E = |
803 | dumpSectionToFile(SecName: SectionName, Filename: FileName, InputFilename: Config.InputFilename, Obj)) |
804 | return E; |
805 | } |
806 | |
807 | // It is important to remove the sections first. For example, we want to |
808 | // remove the relocation sections before removing the symbols. That allows |
809 | // us to avoid reporting the inappropriate errors about removing symbols |
810 | // named in relocations. |
811 | if (Error E = replaceAndRemoveSections(Config, ELFConfig, Obj)) |
812 | return createFileError(F: Config.InputFilename, E: std::move(E)); |
813 | |
814 | if (Error E = updateAndRemoveSymbols(Config, ELFConfig, Obj)) |
815 | return createFileError(F: Config.InputFilename, E: std::move(E)); |
816 | |
817 | if (!Config.SetSectionAlignment.empty()) { |
818 | for (SectionBase &Sec : Obj.sections()) { |
819 | auto I = Config.SetSectionAlignment.find(Key: Sec.Name); |
820 | if (I != Config.SetSectionAlignment.end()) |
821 | Sec.Align = I->second; |
822 | } |
823 | } |
824 | |
825 | if (Config.ChangeSectionLMAValAll != 0) { |
826 | for (Segment &Seg : Obj.segments()) { |
827 | if (Seg.MemSize > 0) { |
828 | if (Config.ChangeSectionLMAValAll > 0 && |
829 | Seg.PAddr > std::numeric_limits<uint64_t>::max() - |
830 | Config.ChangeSectionLMAValAll) { |
831 | return createFileError( |
832 | F: Config.InputFilename, EC: errc::invalid_argument, |
833 | S: "address 0x" + Twine::utohexstr(Val: Seg.PAddr) + |
834 | " cannot be increased by 0x" + |
835 | Twine::utohexstr(Val: Config.ChangeSectionLMAValAll) + |
836 | ". The result would overflow" ); |
837 | } else if (Config.ChangeSectionLMAValAll < 0 && |
838 | Seg.PAddr < std::numeric_limits<uint64_t>::min() - |
839 | Config.ChangeSectionLMAValAll) { |
840 | return createFileError( |
841 | F: Config.InputFilename, EC: errc::invalid_argument, |
842 | S: "address 0x" + Twine::utohexstr(Val: Seg.PAddr) + |
843 | " cannot be decreased by 0x" + |
844 | Twine::utohexstr(Val: std::abs(i: Config.ChangeSectionLMAValAll)) + |
845 | ". The result would underflow" ); |
846 | } |
847 | Seg.PAddr += Config.ChangeSectionLMAValAll; |
848 | } |
849 | } |
850 | } |
851 | |
852 | if (!Config.ChangeSectionAddress.empty()) { |
853 | if (Obj.Type != ELF::ET_REL) |
854 | return createFileError( |
855 | F: Config.InputFilename, EC: object_error::invalid_file_type, |
856 | Fmt: "cannot change section address in a non-relocatable file" ); |
857 | StringMap<AddressUpdate> SectionsToUpdateAddress; |
858 | for (const SectionPatternAddressUpdate &PatternUpdate : |
859 | reverse(C: Config.ChangeSectionAddress)) { |
860 | for (SectionBase &Sec : Obj.sections()) { |
861 | if (PatternUpdate.SectionPattern.matches(S: Sec.Name) && |
862 | SectionsToUpdateAddress.try_emplace(Key: Sec.Name, Args: PatternUpdate.Update) |
863 | .second) { |
864 | if (PatternUpdate.Update.Kind == AdjustKind::Subtract && |
865 | Sec.Addr < PatternUpdate.Update.Value) { |
866 | return createFileError( |
867 | F: Config.InputFilename, EC: errc::invalid_argument, |
868 | S: "address 0x" + Twine::utohexstr(Val: Sec.Addr) + |
869 | " cannot be decreased by 0x" + |
870 | Twine::utohexstr(Val: PatternUpdate.Update.Value) + |
871 | ". The result would underflow" ); |
872 | } |
873 | if (PatternUpdate.Update.Kind == AdjustKind::Add && |
874 | Sec.Addr > std::numeric_limits<uint64_t>::max() - |
875 | PatternUpdate.Update.Value) { |
876 | return createFileError( |
877 | F: Config.InputFilename, EC: errc::invalid_argument, |
878 | S: "address 0x" + Twine::utohexstr(Val: Sec.Addr) + |
879 | " cannot be increased by 0x" + |
880 | Twine::utohexstr(Val: PatternUpdate.Update.Value) + |
881 | ". The result would overflow" ); |
882 | } |
883 | |
884 | switch (PatternUpdate.Update.Kind) { |
885 | case (AdjustKind::Set): |
886 | Sec.Addr = PatternUpdate.Update.Value; |
887 | break; |
888 | case (AdjustKind::Subtract): |
889 | Sec.Addr -= PatternUpdate.Update.Value; |
890 | break; |
891 | case (AdjustKind::Add): |
892 | Sec.Addr += PatternUpdate.Update.Value; |
893 | break; |
894 | } |
895 | } |
896 | } |
897 | } |
898 | } |
899 | |
900 | if (Config.OnlyKeepDebug) |
901 | for (auto &Sec : Obj.sections()) |
902 | if (Sec.Flags & SHF_ALLOC && Sec.Type != SHT_NOTE) |
903 | Sec.Type = SHT_NOBITS; |
904 | |
905 | endianness E = OutputElfType == ELFT_ELF32LE || OutputElfType == ELFT_ELF64LE |
906 | ? endianness::little |
907 | : endianness::big; |
908 | |
909 | if (!ELFConfig.NotesToRemove.empty()) { |
910 | if (Error Err = |
911 | removeNotes(Obj, Endianness: E, NotesToRemove: ELFConfig.NotesToRemove, ErrorCallback: Config.ErrorCallback)) |
912 | return createFileError(F: Config.InputFilename, E: std::move(Err)); |
913 | } |
914 | |
915 | for (const NewSectionInfo &AddedSection : Config.AddSection) { |
916 | auto AddSection = [&](StringRef Name, ArrayRef<uint8_t> Data) -> Error { |
917 | OwnedDataSection &NewSection = |
918 | Obj.addSection<OwnedDataSection>(Args&: Name, Args&: Data); |
919 | if (Name.starts_with(Prefix: ".note" ) && Name != ".note.GNU-stack" ) { |
920 | NewSection.Type = SHT_NOTE; |
921 | if (ELFConfig.VerifyNoteSections) |
922 | return verifyNoteSection(Name, Endianness: E, Data); |
923 | } |
924 | return Error::success(); |
925 | }; |
926 | if (Error E = handleUserSection(NewSection: AddedSection, F: AddSection)) |
927 | return createFileError(F: Config.InputFilename, E: std::move(E)); |
928 | } |
929 | |
930 | for (const NewSectionInfo &NewSection : Config.UpdateSection) { |
931 | auto UpdateSection = [&](StringRef Name, ArrayRef<uint8_t> Data) { |
932 | return Obj.updateSection(Name, Data); |
933 | }; |
934 | if (Error E = handleUserSection(NewSection, F: UpdateSection)) |
935 | return createFileError(F: Config.InputFilename, E: std::move(E)); |
936 | } |
937 | |
938 | if (!Config.AddGnuDebugLink.empty()) |
939 | Obj.addSection<GnuDebugLinkSection>(Args: Config.AddGnuDebugLink, |
940 | Args: Config.GnuDebugLinkCRC32); |
941 | |
942 | // If the symbol table was previously removed, we need to create a new one |
943 | // before adding new symbols. |
944 | if (!Obj.SymbolTable && !Config.SymbolsToAdd.empty()) |
945 | if (Error E = Obj.addNewSymbolTable()) |
946 | return createFileError(F: Config.InputFilename, E: std::move(E)); |
947 | |
948 | for (const NewSymbolInfo &SI : Config.SymbolsToAdd) |
949 | addSymbol(Obj, SymInfo: SI, DefaultVisibility: ELFConfig.NewSymbolVisibility); |
950 | |
951 | // --set-section-{flags,type} work with sections added by --add-section. |
952 | if (!Config.SetSectionFlags.empty() || !Config.SetSectionType.empty()) { |
953 | for (auto &Sec : Obj.sections()) { |
954 | const auto Iter = Config.SetSectionFlags.find(Key: Sec.Name); |
955 | if (Iter != Config.SetSectionFlags.end()) { |
956 | const SectionFlagsUpdate &SFU = Iter->second; |
957 | if (Error E = setSectionFlagsAndType(Sec, Flags: SFU.NewFlags, EMachine: Obj.Machine)) |
958 | return createFileError(F: Config.InputFilename, E: std::move(E)); |
959 | } |
960 | auto It2 = Config.SetSectionType.find(Key: Sec.Name); |
961 | if (It2 != Config.SetSectionType.end()) |
962 | setSectionType(Sec, Type: It2->second); |
963 | } |
964 | } |
965 | |
966 | if (!Config.SectionsToRename.empty()) { |
967 | std::vector<RelocationSectionBase *> RelocSections; |
968 | DenseSet<SectionBase *> RenamedSections; |
969 | for (SectionBase &Sec : Obj.sections()) { |
970 | auto *RelocSec = dyn_cast<RelocationSectionBase>(Val: &Sec); |
971 | const auto Iter = Config.SectionsToRename.find(Key: Sec.Name); |
972 | if (Iter != Config.SectionsToRename.end()) { |
973 | const SectionRename &SR = Iter->second; |
974 | Sec.Name = std::string(SR.NewName); |
975 | if (SR.NewFlags) { |
976 | if (Error E = setSectionFlagsAndType(Sec, Flags: *SR.NewFlags, EMachine: Obj.Machine)) |
977 | return createFileError(F: Config.InputFilename, E: std::move(E)); |
978 | } |
979 | RenamedSections.insert(V: &Sec); |
980 | } else if (RelocSec && !(Sec.Flags & SHF_ALLOC)) |
981 | // Postpone processing relocation sections which are not specified in |
982 | // their explicit '--rename-section' commands until after their target |
983 | // sections are renamed. |
984 | // Dynamic relocation sections (i.e. ones with SHF_ALLOC) should be |
985 | // renamed only explicitly. Otherwise, renaming, for example, '.got.plt' |
986 | // would affect '.rela.plt', which is not desirable. |
987 | RelocSections.push_back(x: RelocSec); |
988 | } |
989 | |
990 | // Rename relocation sections according to their target sections. |
991 | for (RelocationSectionBase *RelocSec : RelocSections) { |
992 | auto Iter = RenamedSections.find(V: RelocSec->getSection()); |
993 | if (Iter != RenamedSections.end()) |
994 | RelocSec->Name = (RelocSec->getNamePrefix() + (*Iter)->Name).str(); |
995 | } |
996 | } |
997 | |
998 | // Add a prefix to allocated sections and their relocation sections. This |
999 | // should be done after renaming the section by Config.SectionToRename to |
1000 | // imitate the GNU objcopy behavior. |
1001 | if (!Config.AllocSectionsPrefix.empty()) { |
1002 | DenseSet<SectionBase *> PrefixedSections; |
1003 | for (SectionBase &Sec : Obj.sections()) { |
1004 | if (Sec.Flags & SHF_ALLOC) { |
1005 | Sec.Name = (Config.AllocSectionsPrefix + Sec.Name).str(); |
1006 | PrefixedSections.insert(V: &Sec); |
1007 | } else if (auto *RelocSec = dyn_cast<RelocationSectionBase>(Val: &Sec)) { |
1008 | // Rename relocation sections associated to the allocated sections. |
1009 | // For example, if we rename .text to .prefix.text, we also rename |
1010 | // .rel.text to .rel.prefix.text. |
1011 | // |
1012 | // Dynamic relocation sections (SHT_REL[A] with SHF_ALLOC) are handled |
1013 | // above, e.g., .rela.plt is renamed to .prefix.rela.plt, not |
1014 | // .rela.prefix.plt since GNU objcopy does so. |
1015 | const SectionBase *TargetSec = RelocSec->getSection(); |
1016 | if (TargetSec && (TargetSec->Flags & SHF_ALLOC)) { |
1017 | // If the relocation section comes *after* the target section, we |
1018 | // don't add Config.AllocSectionsPrefix because we've already added |
1019 | // the prefix to TargetSec->Name. Otherwise, if the relocation |
1020 | // section comes *before* the target section, we add the prefix. |
1021 | if (PrefixedSections.count(V: TargetSec)) |
1022 | Sec.Name = (RelocSec->getNamePrefix() + TargetSec->Name).str(); |
1023 | else |
1024 | Sec.Name = (RelocSec->getNamePrefix() + Config.AllocSectionsPrefix + |
1025 | TargetSec->Name) |
1026 | .str(); |
1027 | } |
1028 | } |
1029 | } |
1030 | } |
1031 | |
1032 | if (ELFConfig.EntryExpr) |
1033 | Obj.Entry = ELFConfig.EntryExpr(Obj.Entry); |
1034 | return Error::success(); |
1035 | } |
1036 | |
1037 | static Error writeOutput(const CommonConfig &Config, Object &Obj, |
1038 | raw_ostream &Out, ElfType OutputElfType) { |
1039 | std::unique_ptr<Writer> Writer = |
1040 | createWriter(Config, Obj, Out, OutputElfType); |
1041 | if (Error E = Writer->finalize()) |
1042 | return E; |
1043 | return Writer->write(); |
1044 | } |
1045 | |
1046 | Error objcopy::elf::executeObjcopyOnIHex(const CommonConfig &Config, |
1047 | const ELFConfig &ELFConfig, |
1048 | MemoryBuffer &In, raw_ostream &Out) { |
1049 | IHexReader Reader(&In); |
1050 | Expected<std::unique_ptr<Object>> Obj = Reader.create(EnsureSymtab: true); |
1051 | if (!Obj) |
1052 | return Obj.takeError(); |
1053 | |
1054 | const ElfType OutputElfType = |
1055 | getOutputElfType(MI: Config.OutputArch.value_or(u: MachineInfo())); |
1056 | if (Error E = handleArgs(Config, ELFConfig, OutputElfType, Obj&: **Obj)) |
1057 | return E; |
1058 | return writeOutput(Config, Obj&: **Obj, Out, OutputElfType); |
1059 | } |
1060 | |
1061 | Error objcopy::elf::executeObjcopyOnRawBinary(const CommonConfig &Config, |
1062 | const ELFConfig &ELFConfig, |
1063 | MemoryBuffer &In, |
1064 | raw_ostream &Out) { |
1065 | BinaryReader Reader(&In, ELFConfig.NewSymbolVisibility); |
1066 | Expected<std::unique_ptr<Object>> Obj = Reader.create(EnsureSymtab: true); |
1067 | if (!Obj) |
1068 | return Obj.takeError(); |
1069 | |
1070 | // Prefer OutputArch (-O<format>) if set, otherwise fallback to BinaryArch |
1071 | // (-B<arch>). |
1072 | const ElfType OutputElfType = |
1073 | getOutputElfType(MI: Config.OutputArch.value_or(u: MachineInfo())); |
1074 | if (Error E = handleArgs(Config, ELFConfig, OutputElfType, Obj&: **Obj)) |
1075 | return E; |
1076 | return writeOutput(Config, Obj&: **Obj, Out, OutputElfType); |
1077 | } |
1078 | |
1079 | Error objcopy::elf::executeObjcopyOnBinary(const CommonConfig &Config, |
1080 | const ELFConfig &ELFConfig, |
1081 | object::ELFObjectFileBase &In, |
1082 | raw_ostream &Out) { |
1083 | ELFReader Reader(&In, Config.ExtractPartition); |
1084 | Expected<std::unique_ptr<Object>> Obj = |
1085 | Reader.create(EnsureSymtab: !Config.SymbolsToAdd.empty()); |
1086 | if (!Obj) |
1087 | return Obj.takeError(); |
1088 | // Prefer OutputArch (-O<format>) if set, otherwise infer it from the input. |
1089 | const ElfType OutputElfType = Config.OutputArch |
1090 | ? getOutputElfType(MI: *Config.OutputArch) |
1091 | : getOutputElfType(Bin: In); |
1092 | |
1093 | if (Error E = handleArgs(Config, ELFConfig, OutputElfType, Obj&: **Obj)) |
1094 | return E; |
1095 | |
1096 | if (Error E = writeOutput(Config, Obj&: **Obj, Out, OutputElfType)) |
1097 | return createFileError(F: Config.InputFilename, E: std::move(E)); |
1098 | |
1099 | return Error::success(); |
1100 | } |
1101 | |