1//===- InputFiles.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 "InputFiles.h"
10#include "Config.h"
11#include "DWARF.h"
12#include "Driver.h"
13#include "InputSection.h"
14#include "LinkerScript.h"
15#include "SymbolTable.h"
16#include "Symbols.h"
17#include "SyntheticSections.h"
18#include "Target.h"
19#include "lld/Common/CommonLinkerContext.h"
20#include "lld/Common/DWARF.h"
21#include "llvm/ADT/CachedHashString.h"
22#include "llvm/ADT/STLExtras.h"
23#include "llvm/LTO/LTO.h"
24#include "llvm/Object/IRObjectFile.h"
25#include "llvm/Support/ARMAttributeParser.h"
26#include "llvm/Support/ARMBuildAttributes.h"
27#include "llvm/Support/Endian.h"
28#include "llvm/Support/FileSystem.h"
29#include "llvm/Support/Path.h"
30#include "llvm/Support/RISCVAttributeParser.h"
31#include "llvm/Support/TarWriter.h"
32#include "llvm/Support/TimeProfiler.h"
33#include "llvm/Support/raw_ostream.h"
34#include <optional>
35
36using namespace llvm;
37using namespace llvm::ELF;
38using namespace llvm::object;
39using namespace llvm::sys;
40using namespace llvm::sys::fs;
41using namespace llvm::support::endian;
42using namespace lld;
43using namespace lld::elf;
44
45// This function is explicitly instantiated in ARM.cpp, don't do it here to
46// avoid warnings with MSVC.
47extern template void ObjFile<ELF32LE>::importCmseSymbols();
48extern template void ObjFile<ELF32BE>::importCmseSymbols();
49extern template void ObjFile<ELF64LE>::importCmseSymbols();
50extern template void ObjFile<ELF64BE>::importCmseSymbols();
51
52bool InputFile::isInGroup;
53uint32_t InputFile::nextGroupId;
54
55std::unique_ptr<TarWriter> elf::tar;
56
57// Returns "<internal>", "foo.a(bar.o)" or "baz.o".
58std::string lld::toString(const InputFile *f) {
59 static std::mutex mu;
60 if (!f)
61 return "<internal>";
62
63 {
64 std::lock_guard<std::mutex> lock(mu);
65 if (f->toStringCache.empty()) {
66 if (f->archiveName.empty())
67 f->toStringCache = f->getName();
68 else
69 (f->archiveName + "(" + f->getName() + ")").toVector(Out&: f->toStringCache);
70 }
71 }
72 return std::string(f->toStringCache);
73}
74
75static ELFKind getELFKind(MemoryBufferRef mb, StringRef archiveName) {
76 unsigned char size;
77 unsigned char endian;
78 std::tie(args&: size, args&: endian) = getElfArchType(Object: mb.getBuffer());
79
80 auto report = [&](StringRef msg) {
81 StringRef filename = mb.getBufferIdentifier();
82 if (archiveName.empty())
83 fatal(msg: filename + ": " + msg);
84 else
85 fatal(msg: archiveName + "(" + filename + "): " + msg);
86 };
87
88 if (!mb.getBuffer().starts_with(Prefix: ElfMagic))
89 report("not an ELF file");
90 if (endian != ELFDATA2LSB && endian != ELFDATA2MSB)
91 report("corrupted ELF file: invalid data encoding");
92 if (size != ELFCLASS32 && size != ELFCLASS64)
93 report("corrupted ELF file: invalid file class");
94
95 size_t bufSize = mb.getBuffer().size();
96 if ((size == ELFCLASS32 && bufSize < sizeof(Elf32_Ehdr)) ||
97 (size == ELFCLASS64 && bufSize < sizeof(Elf64_Ehdr)))
98 report("corrupted ELF file: file is too short");
99
100 if (size == ELFCLASS32)
101 return (endian == ELFDATA2LSB) ? ELF32LEKind : ELF32BEKind;
102 return (endian == ELFDATA2LSB) ? ELF64LEKind : ELF64BEKind;
103}
104
105// For ARM only, to set the EF_ARM_ABI_FLOAT_SOFT or EF_ARM_ABI_FLOAT_HARD
106// flag in the ELF Header we need to look at Tag_ABI_VFP_args to find out how
107// the input objects have been compiled.
108static void updateARMVFPArgs(const ARMAttributeParser &attributes,
109 const InputFile *f) {
110 std::optional<unsigned> attr =
111 attributes.getAttributeValue(tag: ARMBuildAttrs::ABI_VFP_args);
112 if (!attr)
113 // If an ABI tag isn't present then it is implicitly given the value of 0
114 // which maps to ARMBuildAttrs::BaseAAPCS. However many assembler files,
115 // including some in glibc that don't use FP args (and should have value 3)
116 // don't have the attribute so we do not consider an implicit value of 0
117 // as a clash.
118 return;
119
120 unsigned vfpArgs = *attr;
121 ARMVFPArgKind arg;
122 switch (vfpArgs) {
123 case ARMBuildAttrs::BaseAAPCS:
124 arg = ARMVFPArgKind::Base;
125 break;
126 case ARMBuildAttrs::HardFPAAPCS:
127 arg = ARMVFPArgKind::VFP;
128 break;
129 case ARMBuildAttrs::ToolChainFPPCS:
130 // Tool chain specific convention that conforms to neither AAPCS variant.
131 arg = ARMVFPArgKind::ToolChain;
132 break;
133 case ARMBuildAttrs::CompatibleFPAAPCS:
134 // Object compatible with all conventions.
135 return;
136 default:
137 error(msg: toString(f) + ": unknown Tag_ABI_VFP_args value: " + Twine(vfpArgs));
138 return;
139 }
140 // Follow ld.bfd and error if there is a mix of calling conventions.
141 if (config->armVFPArgs != arg && config->armVFPArgs != ARMVFPArgKind::Default)
142 error(msg: toString(f) + ": incompatible Tag_ABI_VFP_args");
143 else
144 config->armVFPArgs = arg;
145}
146
147// The ARM support in lld makes some use of instructions that are not available
148// on all ARM architectures. Namely:
149// - Use of BLX instruction for interworking between ARM and Thumb state.
150// - Use of the extended Thumb branch encoding in relocation.
151// - Use of the MOVT/MOVW instructions in Thumb Thunks.
152// The ARM Attributes section contains information about the architecture chosen
153// at compile time. We follow the convention that if at least one input object
154// is compiled with an architecture that supports these features then lld is
155// permitted to use them.
156static void updateSupportedARMFeatures(const ARMAttributeParser &attributes) {
157 std::optional<unsigned> attr =
158 attributes.getAttributeValue(tag: ARMBuildAttrs::CPU_arch);
159 if (!attr)
160 return;
161 auto arch = *attr;
162 switch (arch) {
163 case ARMBuildAttrs::Pre_v4:
164 case ARMBuildAttrs::v4:
165 case ARMBuildAttrs::v4T:
166 // Architectures prior to v5 do not support BLX instruction
167 break;
168 case ARMBuildAttrs::v5T:
169 case ARMBuildAttrs::v5TE:
170 case ARMBuildAttrs::v5TEJ:
171 case ARMBuildAttrs::v6:
172 case ARMBuildAttrs::v6KZ:
173 case ARMBuildAttrs::v6K:
174 config->armHasBlx = true;
175 // Architectures used in pre-Cortex processors do not support
176 // The J1 = 1 J2 = 1 Thumb branch range extension, with the exception
177 // of Architecture v6T2 (arm1156t2-s and arm1156t2f-s) that do.
178 break;
179 default:
180 // All other Architectures have BLX and extended branch encoding
181 config->armHasBlx = true;
182 config->armJ1J2BranchEncoding = true;
183 if (arch != ARMBuildAttrs::v6_M && arch != ARMBuildAttrs::v6S_M)
184 // All Architectures used in Cortex processors with the exception
185 // of v6-M and v6S-M have the MOVT and MOVW instructions.
186 config->armHasMovtMovw = true;
187 break;
188 }
189
190 // Only ARMv8-M or later architectures have CMSE support.
191 std::optional<unsigned> profile =
192 attributes.getAttributeValue(tag: ARMBuildAttrs::CPU_arch_profile);
193 if (!profile)
194 return;
195 if (arch >= ARMBuildAttrs::CPUArch::v8_M_Base &&
196 profile == ARMBuildAttrs::MicroControllerProfile)
197 config->armCMSESupport = true;
198
199 // The thumb PLT entries require Thumb2 which can be used on multiple archs.
200 // For now, let's limit it to ones where ARM isn't available and we know have
201 // Thumb2.
202 std::optional<unsigned> armISA =
203 attributes.getAttributeValue(tag: ARMBuildAttrs::ARM_ISA_use);
204 std::optional<unsigned> thumb =
205 attributes.getAttributeValue(tag: ARMBuildAttrs::THUMB_ISA_use);
206 config->armHasArmISA |= armISA && *armISA >= ARMBuildAttrs::Allowed;
207 config->armHasThumb2ISA |= thumb && *thumb >= ARMBuildAttrs::AllowThumb32;
208}
209
210InputFile::InputFile(Kind k, MemoryBufferRef m)
211 : mb(m), groupId(nextGroupId), fileKind(k) {
212 // All files within the same --{start,end}-group get the same group ID.
213 // Otherwise, a new file will get a new group ID.
214 if (!isInGroup)
215 ++nextGroupId;
216}
217
218std::optional<MemoryBufferRef> elf::readFile(StringRef path) {
219 llvm::TimeTraceScope timeScope("Load input files", path);
220
221 // The --chroot option changes our virtual root directory.
222 // This is useful when you are dealing with files created by --reproduce.
223 if (!config->chroot.empty() && path.starts_with(Prefix: "/"))
224 path = saver().save(S: config->chroot + path);
225
226 bool remapped = false;
227 auto it = config->remapInputs.find(Val: path);
228 if (it != config->remapInputs.end()) {
229 path = it->second;
230 remapped = true;
231 } else {
232 for (const auto &[pat, toFile] : config->remapInputsWildcards) {
233 if (pat.match(S: path)) {
234 path = toFile;
235 remapped = true;
236 break;
237 }
238 }
239 }
240 if (remapped) {
241 // Use /dev/null to indicate an input file that should be ignored. Change
242 // the path to NUL on Windows.
243#ifdef _WIN32
244 if (path == "/dev/null")
245 path = "NUL";
246#endif
247 }
248
249 log(msg: path);
250 config->dependencyFiles.insert(X: llvm::CachedHashString(path));
251
252 auto mbOrErr = MemoryBuffer::getFile(Filename: path, /*IsText=*/false,
253 /*RequiresNullTerminator=*/false);
254 if (auto ec = mbOrErr.getError()) {
255 error(msg: "cannot open " + path + ": " + ec.message());
256 return std::nullopt;
257 }
258
259 MemoryBufferRef mbref = (*mbOrErr)->getMemBufferRef();
260 ctx.memoryBuffers.push_back(Elt: std::move(*mbOrErr)); // take MB ownership
261
262 if (tar)
263 tar->append(Path: relativeToRoot(path), Data: mbref.getBuffer());
264 return mbref;
265}
266
267// All input object files must be for the same architecture
268// (e.g. it does not make sense to link x86 object files with
269// MIPS object files.) This function checks for that error.
270static bool isCompatible(InputFile *file) {
271 if (!file->isElf() && !isa<BitcodeFile>(Val: file))
272 return true;
273
274 if (file->ekind == config->ekind && file->emachine == config->emachine) {
275 if (config->emachine != EM_MIPS)
276 return true;
277 if (isMipsN32Abi(f: file) == config->mipsN32Abi)
278 return true;
279 }
280
281 StringRef target =
282 !config->bfdname.empty() ? config->bfdname : config->emulation;
283 if (!target.empty()) {
284 error(msg: toString(f: file) + " is incompatible with " + target);
285 return false;
286 }
287
288 InputFile *existing = nullptr;
289 if (!ctx.objectFiles.empty())
290 existing = ctx.objectFiles[0];
291 else if (!ctx.sharedFiles.empty())
292 existing = ctx.sharedFiles[0];
293 else if (!ctx.bitcodeFiles.empty())
294 existing = ctx.bitcodeFiles[0];
295 std::string with;
296 if (existing)
297 with = " with " + toString(f: existing);
298 error(msg: toString(f: file) + " is incompatible" + with);
299 return false;
300}
301
302template <class ELFT> static void doParseFile(InputFile *file) {
303 if (!isCompatible(file))
304 return;
305
306 // Lazy object file
307 if (file->lazy) {
308 if (auto *f = dyn_cast<BitcodeFile>(Val: file)) {
309 ctx.lazyBitcodeFiles.push_back(Elt: f);
310 f->parseLazy();
311 } else {
312 cast<ObjFile<ELFT>>(file)->parseLazy();
313 }
314 return;
315 }
316
317 if (config->trace)
318 message(msg: toString(f: file));
319
320 if (file->kind() == InputFile::ObjKind) {
321 ctx.objectFiles.push_back(Elt: cast<ELFFileBase>(Val: file));
322 cast<ObjFile<ELFT>>(file)->parse();
323 } else if (auto *f = dyn_cast<SharedFile>(Val: file)) {
324 f->parse<ELFT>();
325 } else if (auto *f = dyn_cast<BitcodeFile>(Val: file)) {
326 ctx.bitcodeFiles.push_back(Elt: f);
327 f->parse();
328 } else {
329 ctx.binaryFiles.push_back(Elt: cast<BinaryFile>(Val: file));
330 cast<BinaryFile>(Val: file)->parse();
331 }
332}
333
334// Add symbols in File to the symbol table.
335void elf::parseFile(InputFile *file) { invokeELFT(doParseFile, file); }
336
337// This function is explicitly instantiated in ARM.cpp. Mark it extern here,
338// to avoid warnings when building with MSVC.
339extern template void ObjFile<ELF32LE>::importCmseSymbols();
340extern template void ObjFile<ELF32BE>::importCmseSymbols();
341extern template void ObjFile<ELF64LE>::importCmseSymbols();
342extern template void ObjFile<ELF64BE>::importCmseSymbols();
343
344template <class ELFT>
345static void doParseFiles(const std::vector<InputFile *> &files,
346 InputFile *armCmseImpLib) {
347 // Add all files to the symbol table. This will add almost all symbols that we
348 // need to the symbol table. This process might add files to the link due to
349 // addDependentLibrary.
350 for (size_t i = 0; i < files.size(); ++i) {
351 llvm::TimeTraceScope timeScope("Parse input files", files[i]->getName());
352 doParseFile<ELFT>(files[i]);
353 }
354 if (armCmseImpLib)
355 cast<ObjFile<ELFT>>(*armCmseImpLib).importCmseSymbols();
356}
357
358void elf::parseFiles(const std::vector<InputFile *> &files,
359 InputFile *armCmseImpLib) {
360 llvm::TimeTraceScope timeScope("Parse input files");
361 invokeELFT(doParseFiles, files, armCmseImpLib);
362}
363
364// Concatenates arguments to construct a string representing an error location.
365static std::string createFileLineMsg(StringRef path, unsigned line) {
366 std::string filename = std::string(path::filename(path));
367 std::string lineno = ":" + std::to_string(val: line);
368 if (filename == path)
369 return filename + lineno;
370 return filename + lineno + " (" + path.str() + lineno + ")";
371}
372
373template <class ELFT>
374static std::string getSrcMsgAux(ObjFile<ELFT> &file, const Symbol &sym,
375 const InputSectionBase &sec, uint64_t offset) {
376 // In DWARF, functions and variables are stored to different places.
377 // First, look up a function for a given offset.
378 if (std::optional<DILineInfo> info = file.getDILineInfo(&sec, offset))
379 return createFileLineMsg(path: info->FileName, line: info->Line);
380
381 // If it failed, look up again as a variable.
382 if (std::optional<std::pair<std::string, unsigned>> fileLine =
383 file.getVariableLoc(sym.getName()))
384 return createFileLineMsg(path: fileLine->first, line: fileLine->second);
385
386 // File.sourceFile contains STT_FILE symbol, and that is a last resort.
387 return std::string(file.sourceFile);
388}
389
390std::string InputFile::getSrcMsg(const Symbol &sym, const InputSectionBase &sec,
391 uint64_t offset) {
392 if (kind() != ObjKind)
393 return "";
394 switch (ekind) {
395 default:
396 llvm_unreachable("Invalid kind");
397 case ELF32LEKind:
398 return getSrcMsgAux(file&: cast<ObjFile<ELF32LE>>(Val&: *this), sym, sec, offset);
399 case ELF32BEKind:
400 return getSrcMsgAux(file&: cast<ObjFile<ELF32BE>>(Val&: *this), sym, sec, offset);
401 case ELF64LEKind:
402 return getSrcMsgAux(file&: cast<ObjFile<ELF64LE>>(Val&: *this), sym, sec, offset);
403 case ELF64BEKind:
404 return getSrcMsgAux(file&: cast<ObjFile<ELF64BE>>(Val&: *this), sym, sec, offset);
405 }
406}
407
408StringRef InputFile::getNameForScript() const {
409 if (archiveName.empty())
410 return getName();
411
412 if (nameForScriptCache.empty())
413 nameForScriptCache = (archiveName + Twine(':') + getName()).str();
414
415 return nameForScriptCache;
416}
417
418// An ELF object file may contain a `.deplibs` section. If it exists, the
419// section contains a list of library specifiers such as `m` for libm. This
420// function resolves a given name by finding the first matching library checking
421// the various ways that a library can be specified to LLD. This ELF extension
422// is a form of autolinking and is called `dependent libraries`. It is currently
423// unique to LLVM and lld.
424static void addDependentLibrary(StringRef specifier, const InputFile *f) {
425 if (!config->dependentLibraries)
426 return;
427 if (std::optional<std::string> s = searchLibraryBaseName(path: specifier))
428 ctx.driver.addFile(path: saver().save(S: *s), /*withLOption=*/true);
429 else if (std::optional<std::string> s = findFromSearchPaths(path: specifier))
430 ctx.driver.addFile(path: saver().save(S: *s), /*withLOption=*/true);
431 else if (fs::exists(Path: specifier))
432 ctx.driver.addFile(path: specifier, /*withLOption=*/false);
433 else
434 error(msg: toString(f) +
435 ": unable to find library from dependent library specifier: " +
436 specifier);
437}
438
439// Record the membership of a section group so that in the garbage collection
440// pass, section group members are kept or discarded as a unit.
441template <class ELFT>
442static void handleSectionGroup(ArrayRef<InputSectionBase *> sections,
443 ArrayRef<typename ELFT::Word> entries) {
444 bool hasAlloc = false;
445 for (uint32_t index : entries.slice(1)) {
446 if (index >= sections.size())
447 return;
448 if (InputSectionBase *s = sections[index])
449 if (s != &InputSection::discarded && s->flags & SHF_ALLOC)
450 hasAlloc = true;
451 }
452
453 // If any member has the SHF_ALLOC flag, the whole group is subject to garbage
454 // collection. See the comment in markLive(). This rule retains .debug_types
455 // and .rela.debug_types.
456 if (!hasAlloc)
457 return;
458
459 // Connect the members in a circular doubly-linked list via
460 // nextInSectionGroup.
461 InputSectionBase *head;
462 InputSectionBase *prev = nullptr;
463 for (uint32_t index : entries.slice(1)) {
464 InputSectionBase *s = sections[index];
465 if (!s || s == &InputSection::discarded)
466 continue;
467 if (prev)
468 prev->nextInSectionGroup = s;
469 else
470 head = s;
471 prev = s;
472 }
473 if (prev)
474 prev->nextInSectionGroup = head;
475}
476
477template <class ELFT> DWARFCache *ObjFile<ELFT>::getDwarf() {
478 llvm::call_once(initDwarf, [this]() {
479 dwarf = std::make_unique<DWARFCache>(std::make_unique<DWARFContext>(
480 std::make_unique<LLDDwarfObj<ELFT>>(this), "",
481 [&](Error err) { warn(getName() + ": " + toString(E: std::move(err))); },
482 [&](Error warning) {
483 warn(getName() + ": " + toString(E: std::move(warning)));
484 }));
485 });
486
487 return dwarf.get();
488}
489
490// Returns the pair of file name and line number describing location of data
491// object (variable, array, etc) definition.
492template <class ELFT>
493std::optional<std::pair<std::string, unsigned>>
494ObjFile<ELFT>::getVariableLoc(StringRef name) {
495 return getDwarf()->getVariableLoc(name);
496}
497
498// Returns source line information for a given offset
499// using DWARF debug info.
500template <class ELFT>
501std::optional<DILineInfo>
502ObjFile<ELFT>::getDILineInfo(const InputSectionBase *s, uint64_t offset) {
503 // Detect SectionIndex for specified section.
504 uint64_t sectionIndex = object::SectionedAddress::UndefSection;
505 ArrayRef<InputSectionBase *> sections = s->file->getSections();
506 for (uint64_t curIndex = 0; curIndex < sections.size(); ++curIndex) {
507 if (s == sections[curIndex]) {
508 sectionIndex = curIndex;
509 break;
510 }
511 }
512
513 return getDwarf()->getDILineInfo(offset, sectionIndex);
514}
515
516ELFFileBase::ELFFileBase(Kind k, ELFKind ekind, MemoryBufferRef mb)
517 : InputFile(k, mb) {
518 this->ekind = ekind;
519}
520
521template <typename Elf_Shdr>
522static const Elf_Shdr *findSection(ArrayRef<Elf_Shdr> sections, uint32_t type) {
523 for (const Elf_Shdr &sec : sections)
524 if (sec.sh_type == type)
525 return &sec;
526 return nullptr;
527}
528
529void ELFFileBase::init() {
530 switch (ekind) {
531 case ELF32LEKind:
532 init<ELF32LE>(k: fileKind);
533 break;
534 case ELF32BEKind:
535 init<ELF32BE>(k: fileKind);
536 break;
537 case ELF64LEKind:
538 init<ELF64LE>(k: fileKind);
539 break;
540 case ELF64BEKind:
541 init<ELF64BE>(k: fileKind);
542 break;
543 default:
544 llvm_unreachable("getELFKind");
545 }
546}
547
548template <class ELFT> void ELFFileBase::init(InputFile::Kind k) {
549 using Elf_Shdr = typename ELFT::Shdr;
550 using Elf_Sym = typename ELFT::Sym;
551
552 // Initialize trivial attributes.
553 const ELFFile<ELFT> &obj = getObj<ELFT>();
554 emachine = obj.getHeader().e_machine;
555 osabi = obj.getHeader().e_ident[llvm::ELF::EI_OSABI];
556 abiVersion = obj.getHeader().e_ident[llvm::ELF::EI_ABIVERSION];
557
558 ArrayRef<Elf_Shdr> sections = CHECK(obj.sections(), this);
559 elfShdrs = sections.data();
560 numELFShdrs = sections.size();
561
562 // Find a symbol table.
563 const Elf_Shdr *symtabSec =
564 findSection(sections, k == SharedKind ? SHT_DYNSYM : SHT_SYMTAB);
565
566 if (!symtabSec)
567 return;
568
569 // Initialize members corresponding to a symbol table.
570 firstGlobal = symtabSec->sh_info;
571
572 ArrayRef<Elf_Sym> eSyms = CHECK(obj.symbols(symtabSec), this);
573 if (firstGlobal == 0 || firstGlobal > eSyms.size())
574 fatal(msg: toString(f: this) + ": invalid sh_info in symbol table");
575
576 elfSyms = reinterpret_cast<const void *>(eSyms.data());
577 numELFSyms = uint32_t(eSyms.size());
578 stringTable = CHECK(obj.getStringTableForSymtab(*symtabSec, sections), this);
579}
580
581template <class ELFT>
582uint32_t ObjFile<ELFT>::getSectionIndex(const Elf_Sym &sym) const {
583 return CHECK(
584 this->getObj().getSectionIndex(sym, getELFSyms<ELFT>(), shndxTable),
585 this);
586}
587
588template <class ELFT> void ObjFile<ELFT>::parse(bool ignoreComdats) {
589 object::ELFFile<ELFT> obj = this->getObj();
590 // Read a section table. justSymbols is usually false.
591 if (this->justSymbols) {
592 initializeJustSymbols();
593 initializeSymbols(obj);
594 return;
595 }
596
597 // Handle dependent libraries and selection of section groups as these are not
598 // done in parallel.
599 ArrayRef<Elf_Shdr> objSections = getELFShdrs<ELFT>();
600 StringRef shstrtab = CHECK(obj.getSectionStringTable(objSections), this);
601 uint64_t size = objSections.size();
602 sections.resize(size);
603 for (size_t i = 0; i != size; ++i) {
604 const Elf_Shdr &sec = objSections[i];
605 if (sec.sh_type == SHT_LLVM_DEPENDENT_LIBRARIES && !config->relocatable) {
606 StringRef name = check(obj.getSectionName(sec, shstrtab));
607 ArrayRef<char> data = CHECK(
608 this->getObj().template getSectionContentsAsArray<char>(sec), this);
609 if (!data.empty() && data.back() != '\0') {
610 error(
611 toString(this) +
612 ": corrupted dependent libraries section (unterminated string): " +
613 name);
614 } else {
615 for (const char *d = data.begin(), *e = data.end(); d < e;) {
616 StringRef s(d);
617 addDependentLibrary(s, this);
618 d += s.size() + 1;
619 }
620 }
621 this->sections[i] = &InputSection::discarded;
622 continue;
623 }
624
625 if (sec.sh_type == SHT_ARM_ATTRIBUTES && config->emachine == EM_ARM) {
626 ARMAttributeParser attributes;
627 ArrayRef<uint8_t> contents =
628 check(this->getObj().getSectionContents(sec));
629 StringRef name = check(obj.getSectionName(sec, shstrtab));
630 this->sections[i] = &InputSection::discarded;
631 if (Error e = attributes.parse(section: contents, endian: ekind == ELF32LEKind
632 ? llvm::endianness::little
633 : llvm::endianness::big)) {
634 InputSection isec(*this, sec, name);
635 warn(msg: toString(&isec) + ": " + llvm::toString(E: std::move(e)));
636 } else {
637 updateSupportedARMFeatures(attributes);
638 updateARMVFPArgs(attributes, this);
639
640 // FIXME: Retain the first attribute section we see. The eglibc ARM
641 // dynamic loaders require the presence of an attribute section for
642 // dlopen to work. In a full implementation we would merge all attribute
643 // sections.
644 if (in.attributes == nullptr) {
645 in.attributes = std::make_unique<InputSection>(*this, sec, name);
646 this->sections[i] = in.attributes.get();
647 }
648 }
649 }
650
651 // Producing a static binary with MTE globals is not currently supported,
652 // remove all SHT_AARCH64_MEMTAG_GLOBALS_STATIC sections as they're unused
653 // medatada, and we don't want them to end up in the output file for static
654 // executables.
655 if (sec.sh_type == SHT_AARCH64_MEMTAG_GLOBALS_STATIC &&
656 !canHaveMemtagGlobals()) {
657 this->sections[i] = &InputSection::discarded;
658 continue;
659 }
660
661 if (sec.sh_type != SHT_GROUP)
662 continue;
663 StringRef signature = getShtGroupSignature(sections: objSections, sec);
664 ArrayRef<Elf_Word> entries =
665 CHECK(obj.template getSectionContentsAsArray<Elf_Word>(sec), this);
666 if (entries.empty())
667 fatal(toString(this) + ": empty SHT_GROUP");
668
669 Elf_Word flag = entries[0];
670 if (flag && flag != GRP_COMDAT)
671 fatal(toString(this) + ": unsupported SHT_GROUP format");
672
673 bool keepGroup =
674 (flag & GRP_COMDAT) == 0 || ignoreComdats ||
675 symtab.comdatGroups.try_emplace(CachedHashStringRef(signature), this)
676 .second;
677 if (keepGroup) {
678 if (!config->resolveGroups)
679 this->sections[i] = createInputSection(
680 idx: i, sec, name: check(obj.getSectionName(sec, shstrtab)));
681 continue;
682 }
683
684 // Otherwise, discard group members.
685 for (uint32_t secIndex : entries.slice(1)) {
686 if (secIndex >= size)
687 fatal(toString(this) +
688 ": invalid section index in group: " + Twine(secIndex));
689 this->sections[secIndex] = &InputSection::discarded;
690 }
691 }
692
693 // Read a symbol table.
694 initializeSymbols(obj);
695}
696
697// Sections with SHT_GROUP and comdat bits define comdat section groups.
698// They are identified and deduplicated by group name. This function
699// returns a group name.
700template <class ELFT>
701StringRef ObjFile<ELFT>::getShtGroupSignature(ArrayRef<Elf_Shdr> sections,
702 const Elf_Shdr &sec) {
703 typename ELFT::SymRange symbols = this->getELFSyms<ELFT>();
704 if (sec.sh_info >= symbols.size())
705 fatal(toString(this) + ": invalid symbol index");
706 const typename ELFT::Sym &sym = symbols[sec.sh_info];
707 return CHECK(sym.getName(this->stringTable), this);
708}
709
710template <class ELFT>
711bool ObjFile<ELFT>::shouldMerge(const Elf_Shdr &sec, StringRef name) {
712 // On a regular link we don't merge sections if -O0 (default is -O1). This
713 // sometimes makes the linker significantly faster, although the output will
714 // be bigger.
715 //
716 // Doing the same for -r would create a problem as it would combine sections
717 // with different sh_entsize. One option would be to just copy every SHF_MERGE
718 // section as is to the output. While this would produce a valid ELF file with
719 // usable SHF_MERGE sections, tools like (llvm-)?dwarfdump get confused when
720 // they see two .debug_str. We could have separate logic for combining
721 // SHF_MERGE sections based both on their name and sh_entsize, but that seems
722 // to be more trouble than it is worth. Instead, we just use the regular (-O1)
723 // logic for -r.
724 if (config->optimize == 0 && !config->relocatable)
725 return false;
726
727 // A mergeable section with size 0 is useless because they don't have
728 // any data to merge. A mergeable string section with size 0 can be
729 // argued as invalid because it doesn't end with a null character.
730 // We'll avoid a mess by handling them as if they were non-mergeable.
731 if (sec.sh_size == 0)
732 return false;
733
734 // Check for sh_entsize. The ELF spec is not clear about the zero
735 // sh_entsize. It says that "the member [sh_entsize] contains 0 if
736 // the section does not hold a table of fixed-size entries". We know
737 // that Rust 1.13 produces a string mergeable section with a zero
738 // sh_entsize. Here we just accept it rather than being picky about it.
739 uint64_t entSize = sec.sh_entsize;
740 if (entSize == 0)
741 return false;
742 if (sec.sh_size % entSize)
743 fatal(toString(this) + ":(" + name + "): SHF_MERGE section size (" +
744 Twine(sec.sh_size) + ") must be a multiple of sh_entsize (" +
745 Twine(entSize) + ")");
746
747 if (sec.sh_flags & SHF_WRITE)
748 fatal(toString(this) + ":(" + name +
749 "): writable SHF_MERGE section is not supported");
750
751 return true;
752}
753
754// This is for --just-symbols.
755//
756// --just-symbols is a very minor feature that allows you to link your
757// output against other existing program, so that if you load both your
758// program and the other program into memory, your output can refer the
759// other program's symbols.
760//
761// When the option is given, we link "just symbols". The section table is
762// initialized with null pointers.
763template <class ELFT> void ObjFile<ELFT>::initializeJustSymbols() {
764 sections.resize(numELFShdrs);
765}
766
767static bool isKnownSpecificSectionType(uint32_t t, uint32_t flags) {
768 if (SHT_LOUSER <= t && t <= SHT_HIUSER && !(flags & SHF_ALLOC))
769 return true;
770 if (SHT_LOOS <= t && t <= SHT_HIOS && !(flags & SHF_OS_NONCONFORMING))
771 return true;
772 // Allow all processor-specific types. This is different from GNU ld.
773 return SHT_LOPROC <= t && t <= SHT_HIPROC;
774}
775
776template <class ELFT>
777void ObjFile<ELFT>::initializeSections(bool ignoreComdats,
778 const llvm::object::ELFFile<ELFT> &obj) {
779 ArrayRef<Elf_Shdr> objSections = getELFShdrs<ELFT>();
780 StringRef shstrtab = CHECK(obj.getSectionStringTable(objSections), this);
781 uint64_t size = objSections.size();
782 SmallVector<ArrayRef<Elf_Word>, 0> selectedGroups;
783 for (size_t i = 0; i != size; ++i) {
784 if (this->sections[i] == &InputSection::discarded)
785 continue;
786 const Elf_Shdr &sec = objSections[i];
787 const uint32_t type = sec.sh_type;
788
789 // SHF_EXCLUDE'ed sections are discarded by the linker. However,
790 // if -r is given, we'll let the final link discard such sections.
791 // This is compatible with GNU.
792 if ((sec.sh_flags & SHF_EXCLUDE) && !config->relocatable) {
793 if (type == SHT_LLVM_CALL_GRAPH_PROFILE)
794 cgProfileSectionIndex = i;
795 if (type == SHT_LLVM_ADDRSIG) {
796 // We ignore the address-significance table if we know that the object
797 // file was created by objcopy or ld -r. This is because these tools
798 // will reorder the symbols in the symbol table, invalidating the data
799 // in the address-significance table, which refers to symbols by index.
800 if (sec.sh_link != 0)
801 this->addrsigSec = &sec;
802 else if (config->icf == ICFLevel::Safe)
803 warn(toString(this) +
804 ": --icf=safe conservatively ignores "
805 "SHT_LLVM_ADDRSIG [index " +
806 Twine(i) +
807 "] with sh_link=0 "
808 "(likely created using objcopy or ld -r)");
809 }
810 this->sections[i] = &InputSection::discarded;
811 continue;
812 }
813
814 switch (type) {
815 case SHT_GROUP: {
816 if (!config->relocatable)
817 sections[i] = &InputSection::discarded;
818 StringRef signature =
819 cantFail(this->getELFSyms<ELFT>()[sec.sh_info].getName(stringTable));
820 ArrayRef<Elf_Word> entries =
821 cantFail(obj.template getSectionContentsAsArray<Elf_Word>(sec));
822 if ((entries[0] & GRP_COMDAT) == 0 || ignoreComdats ||
823 symtab.comdatGroups.find(Val: CachedHashStringRef(signature))->second ==
824 this)
825 selectedGroups.push_back(entries);
826 break;
827 }
828 case SHT_SYMTAB_SHNDX:
829 shndxTable = CHECK(obj.getSHNDXTable(sec, objSections), this);
830 break;
831 case SHT_SYMTAB:
832 case SHT_STRTAB:
833 case SHT_REL:
834 case SHT_RELA:
835 case SHT_CREL:
836 case SHT_NULL:
837 break;
838 case SHT_PROGBITS:
839 case SHT_NOTE:
840 case SHT_NOBITS:
841 case SHT_INIT_ARRAY:
842 case SHT_FINI_ARRAY:
843 case SHT_PREINIT_ARRAY:
844 this->sections[i] =
845 createInputSection(idx: i, sec, name: check(obj.getSectionName(sec, shstrtab)));
846 break;
847 case SHT_LLVM_LTO:
848 // Discard .llvm.lto in a relocatable link that does not use the bitcode.
849 // The concatenated output does not properly reflect the linking
850 // semantics. In addition, since we do not use the bitcode wrapper format,
851 // the concatenated raw bitcode would be invalid.
852 if (config->relocatable && !config->fatLTOObjects) {
853 sections[i] = &InputSection::discarded;
854 break;
855 }
856 [[fallthrough]];
857 default:
858 this->sections[i] =
859 createInputSection(idx: i, sec, name: check(obj.getSectionName(sec, shstrtab)));
860 if (type == SHT_LLVM_SYMPART)
861 ctx.hasSympart.store(i: true, m: std::memory_order_relaxed);
862 else if (config->rejectMismatch &&
863 !isKnownSpecificSectionType(type, sec.sh_flags))
864 errorOrWarn(toString(this->sections[i]) + ": unknown section type 0x" +
865 Twine::utohexstr(Val: type));
866 break;
867 }
868 }
869
870 // We have a second loop. It is used to:
871 // 1) handle SHF_LINK_ORDER sections.
872 // 2) create relocation sections. In some cases the section header index of a
873 // relocation section may be smaller than that of the relocated section. In
874 // such cases, the relocation section would attempt to reference a target
875 // section that has not yet been created. For simplicity, delay creation of
876 // relocation sections until now.
877 for (size_t i = 0; i != size; ++i) {
878 if (this->sections[i] == &InputSection::discarded)
879 continue;
880 const Elf_Shdr &sec = objSections[i];
881
882 if (isStaticRelSecType(sec.sh_type)) {
883 // Find a relocation target section and associate this section with that.
884 // Target may have been discarded if it is in a different section group
885 // and the group is discarded, even though it's a violation of the spec.
886 // We handle that situation gracefully by discarding dangling relocation
887 // sections.
888 const uint32_t info = sec.sh_info;
889 InputSectionBase *s = getRelocTarget(idx: i, info);
890 if (!s)
891 continue;
892
893 // ELF spec allows mergeable sections with relocations, but they are rare,
894 // and it is in practice hard to merge such sections by contents, because
895 // applying relocations at end of linking changes section contents. So, we
896 // simply handle such sections as non-mergeable ones. Degrading like this
897 // is acceptable because section merging is optional.
898 if (auto *ms = dyn_cast<MergeInputSection>(Val: s)) {
899 s = makeThreadLocal<InputSection>(
900 args&: ms->file, args&: ms->flags, args&: ms->type, args&: ms->addralign,
901 args: ms->contentMaybeDecompress(), args&: ms->name);
902 sections[info] = s;
903 }
904
905 if (s->relSecIdx != 0)
906 error(
907 msg: toString(s) +
908 ": multiple relocation sections to one section are not supported");
909 s->relSecIdx = i;
910
911 // Relocation sections are usually removed from the output, so return
912 // `nullptr` for the normal case. However, if -r or --emit-relocs is
913 // specified, we need to copy them to the output. (Some post link analysis
914 // tools specify --emit-relocs to obtain the information.)
915 if (config->copyRelocs) {
916 auto *isec = makeThreadLocal<InputSection>(
917 *this, sec, check(obj.getSectionName(sec, shstrtab)));
918 // If the relocated section is discarded (due to /DISCARD/ or
919 // --gc-sections), the relocation section should be discarded as well.
920 s->dependentSections.push_back(NewVal: isec);
921 sections[i] = isec;
922 }
923 continue;
924 }
925
926 // A SHF_LINK_ORDER section with sh_link=0 is handled as if it did not have
927 // the flag.
928 if (!sec.sh_link || !(sec.sh_flags & SHF_LINK_ORDER))
929 continue;
930
931 InputSectionBase *linkSec = nullptr;
932 if (sec.sh_link < size)
933 linkSec = this->sections[sec.sh_link];
934 if (!linkSec)
935 fatal(toString(this) + ": invalid sh_link index: " + Twine(sec.sh_link));
936
937 // A SHF_LINK_ORDER section is discarded if its linked-to section is
938 // discarded.
939 InputSection *isec = cast<InputSection>(this->sections[i]);
940 linkSec->dependentSections.push_back(NewVal: isec);
941 if (!isa<InputSection>(Val: linkSec))
942 error(msg: "a section " + isec->name +
943 " with SHF_LINK_ORDER should not refer a non-regular section: " +
944 toString(linkSec));
945 }
946
947 for (ArrayRef<Elf_Word> entries : selectedGroups)
948 handleSectionGroup<ELFT>(this->sections, entries);
949}
950
951// Read the following info from the .note.gnu.property section and write it to
952// the corresponding fields in `ObjFile`:
953// - Feature flags (32 bits) representing x86 or AArch64 features for
954// hardware-assisted call flow control;
955// - AArch64 PAuth ABI core info (16 bytes).
956template <class ELFT>
957void readGnuProperty(const InputSection &sec, ObjFile<ELFT> &f) {
958 using Elf_Nhdr = typename ELFT::Nhdr;
959 using Elf_Note = typename ELFT::Note;
960
961 ArrayRef<uint8_t> data = sec.content();
962 auto reportFatal = [&](const uint8_t *place, const Twine &msg) {
963 fatal(msg: toString(f: sec.file) + ":(" + sec.name + "+0x" +
964 Twine::utohexstr(Val: place - sec.content().data()) + "): " + msg);
965 };
966 while (!data.empty()) {
967 // Read one NOTE record.
968 auto *nhdr = reinterpret_cast<const Elf_Nhdr *>(data.data());
969 if (data.size() < sizeof(Elf_Nhdr) ||
970 data.size() < nhdr->getSize(sec.addralign))
971 reportFatal(data.data(), "data is too short");
972
973 Elf_Note note(*nhdr);
974 if (nhdr->n_type != NT_GNU_PROPERTY_TYPE_0 || note.getName() != "GNU") {
975 data = data.slice(nhdr->getSize(sec.addralign));
976 continue;
977 }
978
979 uint32_t featureAndType = config->emachine == EM_AARCH64
980 ? GNU_PROPERTY_AARCH64_FEATURE_1_AND
981 : GNU_PROPERTY_X86_FEATURE_1_AND;
982
983 // Read a body of a NOTE record, which consists of type-length-value fields.
984 ArrayRef<uint8_t> desc = note.getDesc(sec.addralign);
985 while (!desc.empty()) {
986 const uint8_t *place = desc.data();
987 if (desc.size() < 8)
988 reportFatal(place, "program property is too short");
989 uint32_t type = read32<ELFT::Endianness>(desc.data());
990 uint32_t size = read32<ELFT::Endianness>(desc.data() + 4);
991 desc = desc.slice(N: 8);
992 if (desc.size() < size)
993 reportFatal(place, "program property is too short");
994
995 if (type == featureAndType) {
996 // We found a FEATURE_1_AND field. There may be more than one of these
997 // in a .note.gnu.property section, for a relocatable object we
998 // accumulate the bits set.
999 if (size < 4)
1000 reportFatal(place, "FEATURE_1_AND entry is too short");
1001 f.andFeatures |= read32<ELFT::Endianness>(desc.data());
1002 } else if (config->emachine == EM_AARCH64 &&
1003 type == GNU_PROPERTY_AARCH64_FEATURE_PAUTH) {
1004 if (!f.aarch64PauthAbiCoreInfo.empty()) {
1005 reportFatal(data.data(),
1006 "multiple GNU_PROPERTY_AARCH64_FEATURE_PAUTH entries are "
1007 "not supported");
1008 } else if (size != 16) {
1009 reportFatal(data.data(), "GNU_PROPERTY_AARCH64_FEATURE_PAUTH entry "
1010 "is invalid: expected 16 bytes, but got " +
1011 Twine(size));
1012 }
1013 f.aarch64PauthAbiCoreInfo = desc;
1014 }
1015
1016 // Padding is present in the note descriptor, if necessary.
1017 desc = desc.slice(alignTo<(ELFT::Is64Bits ? 8 : 4)>(size));
1018 }
1019
1020 // Go to next NOTE record to look for more FEATURE_1_AND descriptions.
1021 data = data.slice(nhdr->getSize(sec.addralign));
1022 }
1023}
1024
1025template <class ELFT>
1026InputSectionBase *ObjFile<ELFT>::getRelocTarget(uint32_t idx, uint32_t info) {
1027 if (info < this->sections.size()) {
1028 InputSectionBase *target = this->sections[info];
1029
1030 // Strictly speaking, a relocation section must be included in the
1031 // group of the section it relocates. However, LLVM 3.3 and earlier
1032 // would fail to do so, so we gracefully handle that case.
1033 if (target == &InputSection::discarded)
1034 return nullptr;
1035
1036 if (target != nullptr)
1037 return target;
1038 }
1039
1040 error(toString(this) + Twine(": relocation section (index ") + Twine(idx) +
1041 ") has invalid sh_info (" + Twine(info) + ")");
1042 return nullptr;
1043}
1044
1045// The function may be called concurrently for different input files. For
1046// allocation, prefer makeThreadLocal which does not require holding a lock.
1047template <class ELFT>
1048InputSectionBase *ObjFile<ELFT>::createInputSection(uint32_t idx,
1049 const Elf_Shdr &sec,
1050 StringRef name) {
1051 if (name.starts_with(Prefix: ".n")) {
1052 // The GNU linker uses .note.GNU-stack section as a marker indicating
1053 // that the code in the object file does not expect that the stack is
1054 // executable (in terms of NX bit). If all input files have the marker,
1055 // the GNU linker adds a PT_GNU_STACK segment to tells the loader to
1056 // make the stack non-executable. Most object files have this section as
1057 // of 2017.
1058 //
1059 // But making the stack non-executable is a norm today for security
1060 // reasons. Failure to do so may result in a serious security issue.
1061 // Therefore, we make LLD always add PT_GNU_STACK unless it is
1062 // explicitly told to do otherwise (by -z execstack). Because the stack
1063 // executable-ness is controlled solely by command line options,
1064 // .note.GNU-stack sections are simply ignored.
1065 if (name == ".note.GNU-stack")
1066 return &InputSection::discarded;
1067
1068 // Object files that use processor features such as Intel Control-Flow
1069 // Enforcement (CET) or AArch64 Branch Target Identification BTI, use a
1070 // .note.gnu.property section containing a bitfield of feature bits like the
1071 // GNU_PROPERTY_X86_FEATURE_1_IBT flag. Read a bitmap containing the flag.
1072 //
1073 // Since we merge bitmaps from multiple object files to create a new
1074 // .note.gnu.property containing a single AND'ed bitmap, we discard an input
1075 // file's .note.gnu.property section.
1076 if (name == ".note.gnu.property") {
1077 readGnuProperty<ELFT>(InputSection(*this, sec, name), *this);
1078 return &InputSection::discarded;
1079 }
1080
1081 // Split stacks is a feature to support a discontiguous stack,
1082 // commonly used in the programming language Go. For the details,
1083 // see https://gcc.gnu.org/wiki/SplitStacks. An object file compiled
1084 // for split stack will include a .note.GNU-split-stack section.
1085 if (name == ".note.GNU-split-stack") {
1086 if (config->relocatable) {
1087 error(
1088 msg: "cannot mix split-stack and non-split-stack in a relocatable link");
1089 return &InputSection::discarded;
1090 }
1091 this->splitStack = true;
1092 return &InputSection::discarded;
1093 }
1094
1095 // An object file compiled for split stack, but where some of the
1096 // functions were compiled with the no_split_stack_attribute will
1097 // include a .note.GNU-no-split-stack section.
1098 if (name == ".note.GNU-no-split-stack") {
1099 this->someNoSplitStack = true;
1100 return &InputSection::discarded;
1101 }
1102
1103 // Strip existing .note.gnu.build-id sections so that the output won't have
1104 // more than one build-id. This is not usually a problem because input
1105 // object files normally don't have .build-id sections, but you can create
1106 // such files by "ld.{bfd,gold,lld} -r --build-id", and we want to guard
1107 // against it.
1108 if (name == ".note.gnu.build-id")
1109 return &InputSection::discarded;
1110 }
1111
1112 // The linker merges EH (exception handling) frames and creates a
1113 // .eh_frame_hdr section for runtime. So we handle them with a special
1114 // class. For relocatable outputs, they are just passed through.
1115 if (name == ".eh_frame" && !config->relocatable)
1116 return makeThreadLocal<EhInputSection>(*this, sec, name);
1117
1118 if ((sec.sh_flags & SHF_MERGE) && shouldMerge(sec, name))
1119 return makeThreadLocal<MergeInputSection>(*this, sec, name);
1120 return makeThreadLocal<InputSection>(*this, sec, name);
1121}
1122
1123// Initialize symbols. symbols is a parallel array to the corresponding ELF
1124// symbol table.
1125template <class ELFT>
1126void ObjFile<ELFT>::initializeSymbols(const object::ELFFile<ELFT> &obj) {
1127 ArrayRef<Elf_Sym> eSyms = this->getELFSyms<ELFT>();
1128 if (numSymbols == 0) {
1129 numSymbols = eSyms.size();
1130 symbols = std::make_unique<Symbol *[]>(numSymbols);
1131 }
1132
1133 // Some entries have been filled by LazyObjFile.
1134 for (size_t i = firstGlobal, end = eSyms.size(); i != end; ++i)
1135 if (!symbols[i])
1136 symbols[i] = symtab.insert(CHECK(eSyms[i].getName(stringTable), this));
1137
1138 // Perform symbol resolution on non-local symbols.
1139 SmallVector<unsigned, 32> undefineds;
1140 for (size_t i = firstGlobal, end = eSyms.size(); i != end; ++i) {
1141 const Elf_Sym &eSym = eSyms[i];
1142 uint32_t secIdx = eSym.st_shndx;
1143 if (secIdx == SHN_UNDEF) {
1144 undefineds.push_back(Elt: i);
1145 continue;
1146 }
1147
1148 uint8_t binding = eSym.getBinding();
1149 uint8_t stOther = eSym.st_other;
1150 uint8_t type = eSym.getType();
1151 uint64_t value = eSym.st_value;
1152 uint64_t size = eSym.st_size;
1153
1154 Symbol *sym = symbols[i];
1155 sym->isUsedInRegularObj = true;
1156 if (LLVM_UNLIKELY(eSym.st_shndx == SHN_COMMON)) {
1157 if (value == 0 || value >= UINT32_MAX)
1158 fatal(toString(this) + ": common symbol '" + sym->getName() +
1159 "' has invalid alignment: " + Twine(value));
1160 hasCommonSyms = true;
1161 sym->resolve(
1162 other: CommonSymbol{this, StringRef(), binding, stOther, type, value, size});
1163 continue;
1164 }
1165
1166 // Handle global defined symbols. Defined::section will be set in postParse.
1167 sym->resolve(other: Defined{this, StringRef(), binding, stOther, type, value, size,
1168 nullptr});
1169 }
1170
1171 // Undefined symbols (excluding those defined relative to non-prevailing
1172 // sections) can trigger recursive extract. Process defined symbols first so
1173 // that the relative order between a defined symbol and an undefined symbol
1174 // does not change the symbol resolution behavior. In addition, a set of
1175 // interconnected symbols will all be resolved to the same file, instead of
1176 // being resolved to different files.
1177 for (unsigned i : undefineds) {
1178 const Elf_Sym &eSym = eSyms[i];
1179 Symbol *sym = symbols[i];
1180 sym->resolve(other: Undefined{this, StringRef(), eSym.getBinding(), eSym.st_other,
1181 eSym.getType()});
1182 sym->isUsedInRegularObj = true;
1183 sym->referenced = true;
1184 }
1185}
1186
1187template <class ELFT>
1188void ObjFile<ELFT>::initSectionsAndLocalSyms(bool ignoreComdats) {
1189 if (!justSymbols)
1190 initializeSections(ignoreComdats, obj: getObj());
1191
1192 if (!firstGlobal)
1193 return;
1194 SymbolUnion *locals = makeThreadLocalN<SymbolUnion>(firstGlobal);
1195 memset(locals, 0, sizeof(SymbolUnion) * firstGlobal);
1196
1197 ArrayRef<Elf_Sym> eSyms = this->getELFSyms<ELFT>();
1198 for (size_t i = 0, end = firstGlobal; i != end; ++i) {
1199 const Elf_Sym &eSym = eSyms[i];
1200 uint32_t secIdx = eSym.st_shndx;
1201 if (LLVM_UNLIKELY(secIdx == SHN_XINDEX))
1202 secIdx = check(getExtendedSymbolTableIndex<ELFT>(eSym, i, shndxTable));
1203 else if (secIdx >= SHN_LORESERVE)
1204 secIdx = 0;
1205 if (LLVM_UNLIKELY(secIdx >= sections.size()))
1206 fatal(toString(this) + ": invalid section index: " + Twine(secIdx));
1207 if (LLVM_UNLIKELY(eSym.getBinding() != STB_LOCAL))
1208 error(toString(this) + ": non-local symbol (" + Twine(i) +
1209 ") found at index < .symtab's sh_info (" + Twine(end) + ")");
1210
1211 InputSectionBase *sec = sections[secIdx];
1212 uint8_t type = eSym.getType();
1213 if (type == STT_FILE)
1214 sourceFile = CHECK(eSym.getName(stringTable), this);
1215 if (LLVM_UNLIKELY(stringTable.size() <= eSym.st_name))
1216 fatal(toString(this) + ": invalid symbol name offset");
1217 StringRef name(stringTable.data() + eSym.st_name);
1218
1219 symbols[i] = reinterpret_cast<Symbol *>(locals + i);
1220 if (eSym.st_shndx == SHN_UNDEF || sec == &InputSection::discarded)
1221 new (symbols[i]) Undefined(this, name, STB_LOCAL, eSym.st_other, type,
1222 /*discardedSecIdx=*/secIdx);
1223 else
1224 new (symbols[i]) Defined(this, name, STB_LOCAL, eSym.st_other, type,
1225 eSym.st_value, eSym.st_size, sec);
1226 symbols[i]->partition = 1;
1227 symbols[i]->isUsedInRegularObj = true;
1228 }
1229}
1230
1231// Called after all ObjFile::parse is called for all ObjFiles. This checks
1232// duplicate symbols and may do symbol property merge in the future.
1233template <class ELFT> void ObjFile<ELFT>::postParse() {
1234 static std::mutex mu;
1235 ArrayRef<Elf_Sym> eSyms = this->getELFSyms<ELFT>();
1236 for (size_t i = firstGlobal, end = eSyms.size(); i != end; ++i) {
1237 const Elf_Sym &eSym = eSyms[i];
1238 Symbol &sym = *symbols[i];
1239 uint32_t secIdx = eSym.st_shndx;
1240 uint8_t binding = eSym.getBinding();
1241 if (LLVM_UNLIKELY(binding != STB_GLOBAL && binding != STB_WEAK &&
1242 binding != STB_GNU_UNIQUE))
1243 errorOrWarn(toString(this) + ": symbol (" + Twine(i) +
1244 ") has invalid binding: " + Twine((int)binding));
1245
1246 // st_value of STT_TLS represents the assigned offset, not the actual
1247 // address which is used by STT_FUNC and STT_OBJECT. STT_TLS symbols can
1248 // only be referenced by special TLS relocations. It is usually an error if
1249 // a STT_TLS symbol is replaced by a non-STT_TLS symbol, vice versa.
1250 if (LLVM_UNLIKELY(sym.isTls()) && eSym.getType() != STT_TLS &&
1251 eSym.getType() != STT_NOTYPE)
1252 errorOrWarn("TLS attribute mismatch: " + toString(sym) + "\n>>> in " +
1253 toString(f: sym.file) + "\n>>> in " + toString(this));
1254
1255 // Handle non-COMMON defined symbol below. !sym.file allows a symbol
1256 // assignment to redefine a symbol without an error.
1257 if (!sym.file || !sym.isDefined() || secIdx == SHN_UNDEF ||
1258 secIdx == SHN_COMMON)
1259 continue;
1260
1261 if (LLVM_UNLIKELY(secIdx == SHN_XINDEX))
1262 secIdx = check(getExtendedSymbolTableIndex<ELFT>(eSym, i, shndxTable));
1263 else if (secIdx >= SHN_LORESERVE)
1264 secIdx = 0;
1265 if (LLVM_UNLIKELY(secIdx >= sections.size()))
1266 fatal(toString(this) + ": invalid section index: " + Twine(secIdx));
1267 InputSectionBase *sec = sections[secIdx];
1268 if (sec == &InputSection::discarded) {
1269 if (sym.traced) {
1270 printTraceSymbol(sym: Undefined{this, sym.getName(), sym.binding,
1271 sym.stOther, sym.type, secIdx},
1272 name: sym.getName());
1273 }
1274 if (sym.file == this) {
1275 std::lock_guard<std::mutex> lock(mu);
1276 ctx.nonPrevailingSyms.emplace_back(Args: &sym, Args&: secIdx);
1277 }
1278 continue;
1279 }
1280
1281 if (sym.file == this) {
1282 cast<Defined>(Val&: sym).section = sec;
1283 continue;
1284 }
1285
1286 if (sym.binding == STB_WEAK || binding == STB_WEAK)
1287 continue;
1288 std::lock_guard<std::mutex> lock(mu);
1289 ctx.duplicates.push_back(Elt: {&sym, this, sec, eSym.st_value});
1290 }
1291}
1292
1293// The handling of tentative definitions (COMMON symbols) in archives is murky.
1294// A tentative definition will be promoted to a global definition if there are
1295// no non-tentative definitions to dominate it. When we hold a tentative
1296// definition to a symbol and are inspecting archive members for inclusion
1297// there are 2 ways we can proceed:
1298//
1299// 1) Consider the tentative definition a 'real' definition (ie promotion from
1300// tentative to real definition has already happened) and not inspect
1301// archive members for Global/Weak definitions to replace the tentative
1302// definition. An archive member would only be included if it satisfies some
1303// other undefined symbol. This is the behavior Gold uses.
1304//
1305// 2) Consider the tentative definition as still undefined (ie the promotion to
1306// a real definition happens only after all symbol resolution is done).
1307// The linker searches archive members for STB_GLOBAL definitions to
1308// replace the tentative definition with. This is the behavior used by
1309// GNU ld.
1310//
1311// The second behavior is inherited from SysVR4, which based it on the FORTRAN
1312// COMMON BLOCK model. This behavior is needed for proper initialization in old
1313// (pre F90) FORTRAN code that is packaged into an archive.
1314//
1315// The following functions search archive members for definitions to replace
1316// tentative definitions (implementing behavior 2).
1317static bool isBitcodeNonCommonDef(MemoryBufferRef mb, StringRef symName,
1318 StringRef archiveName) {
1319 IRSymtabFile symtabFile = check(e: readIRSymtab(MBRef: mb));
1320 for (const irsymtab::Reader::SymbolRef &sym :
1321 symtabFile.TheReader.symbols()) {
1322 if (sym.isGlobal() && sym.getName() == symName)
1323 return !sym.isUndefined() && !sym.isWeak() && !sym.isCommon();
1324 }
1325 return false;
1326}
1327
1328template <class ELFT>
1329static bool isNonCommonDef(ELFKind ekind, MemoryBufferRef mb, StringRef symName,
1330 StringRef archiveName) {
1331 ObjFile<ELFT> *obj = make<ObjFile<ELFT>>(ekind, mb, archiveName);
1332 obj->init();
1333 StringRef stringtable = obj->getStringTable();
1334
1335 for (auto sym : obj->template getGlobalELFSyms<ELFT>()) {
1336 Expected<StringRef> name = sym.getName(stringtable);
1337 if (name && name.get() == symName)
1338 return sym.isDefined() && sym.getBinding() == STB_GLOBAL &&
1339 !sym.isCommon();
1340 }
1341 return false;
1342}
1343
1344static bool isNonCommonDef(MemoryBufferRef mb, StringRef symName,
1345 StringRef archiveName) {
1346 switch (getELFKind(mb, archiveName)) {
1347 case ELF32LEKind:
1348 return isNonCommonDef<ELF32LE>(ekind: ELF32LEKind, mb, symName, archiveName);
1349 case ELF32BEKind:
1350 return isNonCommonDef<ELF32BE>(ekind: ELF32BEKind, mb, symName, archiveName);
1351 case ELF64LEKind:
1352 return isNonCommonDef<ELF64LE>(ekind: ELF64LEKind, mb, symName, archiveName);
1353 case ELF64BEKind:
1354 return isNonCommonDef<ELF64BE>(ekind: ELF64BEKind, mb, symName, archiveName);
1355 default:
1356 llvm_unreachable("getELFKind");
1357 }
1358}
1359
1360unsigned SharedFile::vernauxNum;
1361
1362SharedFile::SharedFile(MemoryBufferRef m, StringRef defaultSoName)
1363 : ELFFileBase(SharedKind, getELFKind(mb: m, archiveName: ""), m), soName(defaultSoName),
1364 isNeeded(!config->asNeeded) {}
1365
1366// Parse the version definitions in the object file if present, and return a
1367// vector whose nth element contains a pointer to the Elf_Verdef for version
1368// identifier n. Version identifiers that are not definitions map to nullptr.
1369template <typename ELFT>
1370static SmallVector<const void *, 0>
1371parseVerdefs(const uint8_t *base, const typename ELFT::Shdr *sec) {
1372 if (!sec)
1373 return {};
1374
1375 // Build the Verdefs array by following the chain of Elf_Verdef objects
1376 // from the start of the .gnu.version_d section.
1377 SmallVector<const void *, 0> verdefs;
1378 const uint8_t *verdef = base + sec->sh_offset;
1379 for (unsigned i = 0, e = sec->sh_info; i != e; ++i) {
1380 auto *curVerdef = reinterpret_cast<const typename ELFT::Verdef *>(verdef);
1381 verdef += curVerdef->vd_next;
1382 unsigned verdefIndex = curVerdef->vd_ndx;
1383 if (verdefIndex >= verdefs.size())
1384 verdefs.resize(N: verdefIndex + 1);
1385 verdefs[verdefIndex] = curVerdef;
1386 }
1387 return verdefs;
1388}
1389
1390// Parse SHT_GNU_verneed to properly set the name of a versioned undefined
1391// symbol. We detect fatal issues which would cause vulnerabilities, but do not
1392// implement sophisticated error checking like in llvm-readobj because the value
1393// of such diagnostics is low.
1394template <typename ELFT>
1395std::vector<uint32_t> SharedFile::parseVerneed(const ELFFile<ELFT> &obj,
1396 const typename ELFT::Shdr *sec) {
1397 if (!sec)
1398 return {};
1399 std::vector<uint32_t> verneeds;
1400 ArrayRef<uint8_t> data = CHECK(obj.getSectionContents(*sec), this);
1401 const uint8_t *verneedBuf = data.begin();
1402 for (unsigned i = 0; i != sec->sh_info; ++i) {
1403 if (verneedBuf + sizeof(typename ELFT::Verneed) > data.end())
1404 fatal(msg: toString(f: this) + " has an invalid Verneed");
1405 auto *vn = reinterpret_cast<const typename ELFT::Verneed *>(verneedBuf);
1406 const uint8_t *vernauxBuf = verneedBuf + vn->vn_aux;
1407 for (unsigned j = 0; j != vn->vn_cnt; ++j) {
1408 if (vernauxBuf + sizeof(typename ELFT::Vernaux) > data.end())
1409 fatal(msg: toString(f: this) + " has an invalid Vernaux");
1410 auto *aux = reinterpret_cast<const typename ELFT::Vernaux *>(vernauxBuf);
1411 if (aux->vna_name >= this->stringTable.size())
1412 fatal(msg: toString(f: this) + " has a Vernaux with an invalid vna_name");
1413 uint16_t version = aux->vna_other & VERSYM_VERSION;
1414 if (version >= verneeds.size())
1415 verneeds.resize(new_size: version + 1);
1416 verneeds[version] = aux->vna_name;
1417 vernauxBuf += aux->vna_next;
1418 }
1419 verneedBuf += vn->vn_next;
1420 }
1421 return verneeds;
1422}
1423
1424// We do not usually care about alignments of data in shared object
1425// files because the loader takes care of it. However, if we promote a
1426// DSO symbol to point to .bss due to copy relocation, we need to keep
1427// the original alignment requirements. We infer it in this function.
1428template <typename ELFT>
1429static uint64_t getAlignment(ArrayRef<typename ELFT::Shdr> sections,
1430 const typename ELFT::Sym &sym) {
1431 uint64_t ret = UINT64_MAX;
1432 if (sym.st_value)
1433 ret = 1ULL << llvm::countr_zero(Val: (uint64_t)sym.st_value);
1434 if (0 < sym.st_shndx && sym.st_shndx < sections.size())
1435 ret = std::min<uint64_t>(ret, sections[sym.st_shndx].sh_addralign);
1436 return (ret > UINT32_MAX) ? 0 : ret;
1437}
1438
1439// Fully parse the shared object file.
1440//
1441// This function parses symbol versions. If a DSO has version information,
1442// the file has a ".gnu.version_d" section which contains symbol version
1443// definitions. Each symbol is associated to one version through a table in
1444// ".gnu.version" section. That table is a parallel array for the symbol
1445// table, and each table entry contains an index in ".gnu.version_d".
1446//
1447// The special index 0 is reserved for VERF_NDX_LOCAL and 1 is for
1448// VER_NDX_GLOBAL. There's no table entry for these special versions in
1449// ".gnu.version_d".
1450//
1451// The file format for symbol versioning is perhaps a bit more complicated
1452// than necessary, but you can easily understand the code if you wrap your
1453// head around the data structure described above.
1454template <class ELFT> void SharedFile::parse() {
1455 using Elf_Dyn = typename ELFT::Dyn;
1456 using Elf_Shdr = typename ELFT::Shdr;
1457 using Elf_Sym = typename ELFT::Sym;
1458 using Elf_Verdef = typename ELFT::Verdef;
1459 using Elf_Versym = typename ELFT::Versym;
1460
1461 ArrayRef<Elf_Dyn> dynamicTags;
1462 const ELFFile<ELFT> obj = this->getObj<ELFT>();
1463 ArrayRef<Elf_Shdr> sections = getELFShdrs<ELFT>();
1464
1465 const Elf_Shdr *versymSec = nullptr;
1466 const Elf_Shdr *verdefSec = nullptr;
1467 const Elf_Shdr *verneedSec = nullptr;
1468
1469 // Search for .dynsym, .dynamic, .symtab, .gnu.version and .gnu.version_d.
1470 for (const Elf_Shdr &sec : sections) {
1471 switch (sec.sh_type) {
1472 default:
1473 continue;
1474 case SHT_DYNAMIC:
1475 dynamicTags =
1476 CHECK(obj.template getSectionContentsAsArray<Elf_Dyn>(sec), this);
1477 break;
1478 case SHT_GNU_versym:
1479 versymSec = &sec;
1480 break;
1481 case SHT_GNU_verdef:
1482 verdefSec = &sec;
1483 break;
1484 case SHT_GNU_verneed:
1485 verneedSec = &sec;
1486 break;
1487 }
1488 }
1489
1490 if (versymSec && numELFSyms == 0) {
1491 error(msg: "SHT_GNU_versym should be associated with symbol table");
1492 return;
1493 }
1494
1495 // Search for a DT_SONAME tag to initialize this->soName.
1496 for (const Elf_Dyn &dyn : dynamicTags) {
1497 if (dyn.d_tag == DT_NEEDED) {
1498 uint64_t val = dyn.getVal();
1499 if (val >= this->stringTable.size())
1500 fatal(msg: toString(f: this) + ": invalid DT_NEEDED entry");
1501 dtNeeded.push_back(Elt: this->stringTable.data() + val);
1502 } else if (dyn.d_tag == DT_SONAME) {
1503 uint64_t val = dyn.getVal();
1504 if (val >= this->stringTable.size())
1505 fatal(msg: toString(f: this) + ": invalid DT_SONAME entry");
1506 soName = this->stringTable.data() + val;
1507 }
1508 }
1509
1510 // DSOs are uniquified not by filename but by soname.
1511 DenseMap<CachedHashStringRef, SharedFile *>::iterator it;
1512 bool wasInserted;
1513 std::tie(args&: it, args&: wasInserted) =
1514 symtab.soNames.try_emplace(Key: CachedHashStringRef(soName), Args: this);
1515
1516 // If a DSO appears more than once on the command line with and without
1517 // --as-needed, --no-as-needed takes precedence over --as-needed because a
1518 // user can add an extra DSO with --no-as-needed to force it to be added to
1519 // the dependency list.
1520 it->second->isNeeded |= isNeeded;
1521 if (!wasInserted)
1522 return;
1523
1524 ctx.sharedFiles.push_back(Elt: this);
1525
1526 verdefs = parseVerdefs<ELFT>(obj.base(), verdefSec);
1527 std::vector<uint32_t> verneeds = parseVerneed<ELFT>(obj, verneedSec);
1528
1529 // Parse ".gnu.version" section which is a parallel array for the symbol
1530 // table. If a given file doesn't have a ".gnu.version" section, we use
1531 // VER_NDX_GLOBAL.
1532 size_t size = numELFSyms - firstGlobal;
1533 std::vector<uint16_t> versyms(size, VER_NDX_GLOBAL);
1534 if (versymSec) {
1535 ArrayRef<Elf_Versym> versym =
1536 CHECK(obj.template getSectionContentsAsArray<Elf_Versym>(*versymSec),
1537 this)
1538 .slice(firstGlobal);
1539 for (size_t i = 0; i < size; ++i)
1540 versyms[i] = versym[i].vs_index;
1541 }
1542
1543 // System libraries can have a lot of symbols with versions. Using a
1544 // fixed buffer for computing the versions name (foo@ver) can save a
1545 // lot of allocations.
1546 SmallString<0> versionedNameBuffer;
1547
1548 // Add symbols to the symbol table.
1549 ArrayRef<Elf_Sym> syms = this->getGlobalELFSyms<ELFT>();
1550 for (size_t i = 0, e = syms.size(); i != e; ++i) {
1551 const Elf_Sym &sym = syms[i];
1552
1553 // ELF spec requires that all local symbols precede weak or global
1554 // symbols in each symbol table, and the index of first non-local symbol
1555 // is stored to sh_info. If a local symbol appears after some non-local
1556 // symbol, that's a violation of the spec.
1557 StringRef name = CHECK(sym.getName(stringTable), this);
1558 if (sym.getBinding() == STB_LOCAL) {
1559 errorOrWarn(msg: toString(f: this) + ": invalid local symbol '" + name +
1560 "' in global part of symbol table");
1561 continue;
1562 }
1563
1564 const uint16_t ver = versyms[i], idx = ver & ~VERSYM_HIDDEN;
1565 if (sym.isUndefined()) {
1566 // For unversioned undefined symbols, VER_NDX_GLOBAL makes more sense but
1567 // as of binutils 2.34, GNU ld produces VER_NDX_LOCAL.
1568 if (ver != VER_NDX_LOCAL && ver != VER_NDX_GLOBAL) {
1569 if (idx >= verneeds.size()) {
1570 error(msg: "corrupt input file: version need index " + Twine(idx) +
1571 " for symbol " + name + " is out of bounds\n>>> defined in " +
1572 toString(f: this));
1573 continue;
1574 }
1575 StringRef verName = stringTable.data() + verneeds[idx];
1576 versionedNameBuffer.clear();
1577 name = saver().save(
1578 S: (name + "@" + verName).toStringRef(Out&: versionedNameBuffer));
1579 }
1580 Symbol *s = symtab.addSymbol(
1581 newSym: Undefined{this, name, sym.getBinding(), sym.st_other, sym.getType()});
1582 s->exportDynamic = true;
1583 if (sym.getBinding() != STB_WEAK &&
1584 config->unresolvedSymbolsInShlib != UnresolvedPolicy::Ignore)
1585 requiredSymbols.push_back(Elt: s);
1586 continue;
1587 }
1588
1589 if (ver == VER_NDX_LOCAL ||
1590 (ver != VER_NDX_GLOBAL && idx >= verdefs.size())) {
1591 // In GNU ld < 2.31 (before 3be08ea4728b56d35e136af4e6fd3086ade17764), the
1592 // MIPS port puts _gp_disp symbol into DSO files and incorrectly assigns
1593 // VER_NDX_LOCAL. Workaround this bug.
1594 if (config->emachine == EM_MIPS && name == "_gp_disp")
1595 continue;
1596 error(msg: "corrupt input file: version definition index " + Twine(idx) +
1597 " for symbol " + name + " is out of bounds\n>>> defined in " +
1598 toString(f: this));
1599 continue;
1600 }
1601
1602 uint32_t alignment = getAlignment<ELFT>(sections, sym);
1603 if (ver == idx) {
1604 auto *s = symtab.addSymbol(
1605 newSym: SharedSymbol{*this, name, sym.getBinding(), sym.st_other,
1606 sym.getType(), sym.st_value, sym.st_size, alignment});
1607 s->dsoDefined = true;
1608 if (s->file == this)
1609 s->versionId = ver;
1610 }
1611
1612 // Also add the symbol with the versioned name to handle undefined symbols
1613 // with explicit versions.
1614 if (ver == VER_NDX_GLOBAL)
1615 continue;
1616
1617 StringRef verName =
1618 stringTable.data() +
1619 reinterpret_cast<const Elf_Verdef *>(verdefs[idx])->getAux()->vda_name;
1620 versionedNameBuffer.clear();
1621 name = (name + "@" + verName).toStringRef(Out&: versionedNameBuffer);
1622 auto *s = symtab.addSymbol(
1623 newSym: SharedSymbol{*this, saver().save(S: name), sym.getBinding(), sym.st_other,
1624 sym.getType(), sym.st_value, sym.st_size, alignment});
1625 s->dsoDefined = true;
1626 if (s->file == this)
1627 s->versionId = idx;
1628 }
1629}
1630
1631static ELFKind getBitcodeELFKind(const Triple &t) {
1632 if (t.isLittleEndian())
1633 return t.isArch64Bit() ? ELF64LEKind : ELF32LEKind;
1634 return t.isArch64Bit() ? ELF64BEKind : ELF32BEKind;
1635}
1636
1637static uint16_t getBitcodeMachineKind(StringRef path, const Triple &t) {
1638 switch (t.getArch()) {
1639 case Triple::aarch64:
1640 case Triple::aarch64_be:
1641 return EM_AARCH64;
1642 case Triple::amdgcn:
1643 case Triple::r600:
1644 return EM_AMDGPU;
1645 case Triple::arm:
1646 case Triple::armeb:
1647 case Triple::thumb:
1648 case Triple::thumbeb:
1649 return EM_ARM;
1650 case Triple::avr:
1651 return EM_AVR;
1652 case Triple::hexagon:
1653 return EM_HEXAGON;
1654 case Triple::loongarch32:
1655 case Triple::loongarch64:
1656 return EM_LOONGARCH;
1657 case Triple::mips:
1658 case Triple::mipsel:
1659 case Triple::mips64:
1660 case Triple::mips64el:
1661 return EM_MIPS;
1662 case Triple::msp430:
1663 return EM_MSP430;
1664 case Triple::ppc:
1665 case Triple::ppcle:
1666 return EM_PPC;
1667 case Triple::ppc64:
1668 case Triple::ppc64le:
1669 return EM_PPC64;
1670 case Triple::riscv32:
1671 case Triple::riscv64:
1672 return EM_RISCV;
1673 case Triple::sparcv9:
1674 return EM_SPARCV9;
1675 case Triple::systemz:
1676 return EM_S390;
1677 case Triple::x86:
1678 return t.isOSIAMCU() ? EM_IAMCU : EM_386;
1679 case Triple::x86_64:
1680 return EM_X86_64;
1681 default:
1682 error(msg: path + ": could not infer e_machine from bitcode target triple " +
1683 t.str());
1684 return EM_NONE;
1685 }
1686}
1687
1688static uint8_t getOsAbi(const Triple &t) {
1689 switch (t.getOS()) {
1690 case Triple::AMDHSA:
1691 return ELF::ELFOSABI_AMDGPU_HSA;
1692 case Triple::AMDPAL:
1693 return ELF::ELFOSABI_AMDGPU_PAL;
1694 case Triple::Mesa3D:
1695 return ELF::ELFOSABI_AMDGPU_MESA3D;
1696 default:
1697 return ELF::ELFOSABI_NONE;
1698 }
1699}
1700
1701BitcodeFile::BitcodeFile(MemoryBufferRef mb, StringRef archiveName,
1702 uint64_t offsetInArchive, bool lazy)
1703 : InputFile(BitcodeKind, mb) {
1704 this->archiveName = archiveName;
1705 this->lazy = lazy;
1706
1707 std::string path = mb.getBufferIdentifier().str();
1708 if (config->thinLTOIndexOnly)
1709 path = replaceThinLTOSuffix(path: mb.getBufferIdentifier());
1710
1711 // ThinLTO assumes that all MemoryBufferRefs given to it have a unique
1712 // name. If two archives define two members with the same name, this
1713 // causes a collision which result in only one of the objects being taken
1714 // into consideration at LTO time (which very likely causes undefined
1715 // symbols later in the link stage). So we append file offset to make
1716 // filename unique.
1717 StringRef name = archiveName.empty()
1718 ? saver().save(S: path)
1719 : saver().save(S: archiveName + "(" + path::filename(path) +
1720 " at " + utostr(X: offsetInArchive) + ")");
1721 MemoryBufferRef mbref(mb.getBuffer(), name);
1722
1723 obj = CHECK(lto::InputFile::create(mbref), this);
1724
1725 Triple t(obj->getTargetTriple());
1726 ekind = getBitcodeELFKind(t);
1727 emachine = getBitcodeMachineKind(path: mb.getBufferIdentifier(), t);
1728 osabi = getOsAbi(t);
1729}
1730
1731static uint8_t mapVisibility(GlobalValue::VisibilityTypes gvVisibility) {
1732 switch (gvVisibility) {
1733 case GlobalValue::DefaultVisibility:
1734 return STV_DEFAULT;
1735 case GlobalValue::HiddenVisibility:
1736 return STV_HIDDEN;
1737 case GlobalValue::ProtectedVisibility:
1738 return STV_PROTECTED;
1739 }
1740 llvm_unreachable("unknown visibility");
1741}
1742
1743static void
1744createBitcodeSymbol(Symbol *&sym, const std::vector<bool> &keptComdats,
1745 const lto::InputFile::Symbol &objSym, BitcodeFile &f) {
1746 uint8_t binding = objSym.isWeak() ? STB_WEAK : STB_GLOBAL;
1747 uint8_t type = objSym.isTLS() ? STT_TLS : STT_NOTYPE;
1748 uint8_t visibility = mapVisibility(gvVisibility: objSym.getVisibility());
1749
1750 if (!sym)
1751 sym = symtab.insert(name: saver().save(S: objSym.getName()));
1752
1753 int c = objSym.getComdatIndex();
1754 if (objSym.isUndefined() || (c != -1 && !keptComdats[c])) {
1755 Undefined newSym(&f, StringRef(), binding, visibility, type);
1756 sym->resolve(other: newSym);
1757 sym->referenced = true;
1758 return;
1759 }
1760
1761 if (objSym.isCommon()) {
1762 sym->resolve(other: CommonSymbol{&f, StringRef(), binding, visibility, STT_OBJECT,
1763 objSym.getCommonAlignment(),
1764 objSym.getCommonSize()});
1765 } else {
1766 Defined newSym(&f, StringRef(), binding, visibility, type, 0, 0, nullptr);
1767 if (objSym.canBeOmittedFromSymbolTable())
1768 newSym.exportDynamic = false;
1769 sym->resolve(other: newSym);
1770 }
1771}
1772
1773void BitcodeFile::parse() {
1774 for (std::pair<StringRef, Comdat::SelectionKind> s : obj->getComdatTable()) {
1775 keptComdats.push_back(
1776 x: s.second == Comdat::NoDeduplicate ||
1777 symtab.comdatGroups.try_emplace(Key: CachedHashStringRef(s.first), Args: this)
1778 .second);
1779 }
1780
1781 if (numSymbols == 0) {
1782 numSymbols = obj->symbols().size();
1783 symbols = std::make_unique<Symbol *[]>(num: numSymbols);
1784 }
1785 // Process defined symbols first. See the comment in
1786 // ObjFile<ELFT>::initializeSymbols.
1787 for (auto [i, irSym] : llvm::enumerate(First: obj->symbols()))
1788 if (!irSym.isUndefined())
1789 createBitcodeSymbol(sym&: symbols[i], keptComdats, objSym: irSym, f&: *this);
1790 for (auto [i, irSym] : llvm::enumerate(First: obj->symbols()))
1791 if (irSym.isUndefined())
1792 createBitcodeSymbol(sym&: symbols[i], keptComdats, objSym: irSym, f&: *this);
1793
1794 for (auto l : obj->getDependentLibraries())
1795 addDependentLibrary(specifier: l, f: this);
1796}
1797
1798void BitcodeFile::parseLazy() {
1799 numSymbols = obj->symbols().size();
1800 symbols = std::make_unique<Symbol *[]>(num: numSymbols);
1801 for (auto [i, irSym] : llvm::enumerate(First: obj->symbols()))
1802 if (!irSym.isUndefined()) {
1803 auto *sym = symtab.insert(name: saver().save(S: irSym.getName()));
1804 sym->resolve(other: LazySymbol{*this});
1805 symbols[i] = sym;
1806 }
1807}
1808
1809void BitcodeFile::postParse() {
1810 for (auto [i, irSym] : llvm::enumerate(First: obj->symbols())) {
1811 const Symbol &sym = *symbols[i];
1812 if (sym.file == this || !sym.isDefined() || irSym.isUndefined() ||
1813 irSym.isCommon() || irSym.isWeak())
1814 continue;
1815 int c = irSym.getComdatIndex();
1816 if (c != -1 && !keptComdats[c])
1817 continue;
1818 reportDuplicate(sym, newFile: this, errSec: nullptr, errOffset: 0);
1819 }
1820}
1821
1822void BinaryFile::parse() {
1823 ArrayRef<uint8_t> data = arrayRefFromStringRef(Input: mb.getBuffer());
1824 auto *section = make<InputSection>(args: this, args: SHF_ALLOC | SHF_WRITE, args: SHT_PROGBITS,
1825 args: 8, args&: data, args: ".data");
1826 sections.push_back(Elt: section);
1827
1828 // For each input file foo that is embedded to a result as a binary
1829 // blob, we define _binary_foo_{start,end,size} symbols, so that
1830 // user programs can access blobs by name. Non-alphanumeric
1831 // characters in a filename are replaced with underscore.
1832 std::string s = "_binary_" + mb.getBufferIdentifier().str();
1833 for (char &c : s)
1834 if (!isAlnum(C: c))
1835 c = '_';
1836
1837 llvm::StringSaver &saver = lld::saver();
1838
1839 symtab.addAndCheckDuplicate(newSym: Defined{this, saver.save(S: s + "_start"),
1840 STB_GLOBAL, STV_DEFAULT, STT_OBJECT, 0, 0,
1841 section});
1842 symtab.addAndCheckDuplicate(newSym: Defined{this, saver.save(S: s + "_end"), STB_GLOBAL,
1843 STV_DEFAULT, STT_OBJECT, data.size(), 0,
1844 section});
1845 symtab.addAndCheckDuplicate(newSym: Defined{this, saver.save(S: s + "_size"), STB_GLOBAL,
1846 STV_DEFAULT, STT_OBJECT, data.size(), 0,
1847 nullptr});
1848}
1849
1850InputFile *elf::createInternalFile(StringRef name) {
1851 auto *file =
1852 make<InputFile>(args: InputFile::InternalKind, args: MemoryBufferRef("", name));
1853 // References from an internal file do not lead to --warn-backrefs
1854 // diagnostics.
1855 file->groupId = 0;
1856 return file;
1857}
1858
1859ELFFileBase *elf::createObjFile(MemoryBufferRef mb, StringRef archiveName,
1860 bool lazy) {
1861 ELFFileBase *f;
1862 switch (getELFKind(mb, archiveName)) {
1863 case ELF32LEKind:
1864 f = make<ObjFile<ELF32LE>>(args: ELF32LEKind, args&: mb, args&: archiveName);
1865 break;
1866 case ELF32BEKind:
1867 f = make<ObjFile<ELF32BE>>(args: ELF32BEKind, args&: mb, args&: archiveName);
1868 break;
1869 case ELF64LEKind:
1870 f = make<ObjFile<ELF64LE>>(args: ELF64LEKind, args&: mb, args&: archiveName);
1871 break;
1872 case ELF64BEKind:
1873 f = make<ObjFile<ELF64BE>>(args: ELF64BEKind, args&: mb, args&: archiveName);
1874 break;
1875 default:
1876 llvm_unreachable("getELFKind");
1877 }
1878 f->init();
1879 f->lazy = lazy;
1880 return f;
1881}
1882
1883template <class ELFT> void ObjFile<ELFT>::parseLazy() {
1884 const ArrayRef<typename ELFT::Sym> eSyms = this->getELFSyms<ELFT>();
1885 numSymbols = eSyms.size();
1886 symbols = std::make_unique<Symbol *[]>(numSymbols);
1887
1888 // resolve() may trigger this->extract() if an existing symbol is an undefined
1889 // symbol. If that happens, this function has served its purpose, and we can
1890 // exit from the loop early.
1891 for (size_t i = firstGlobal, end = eSyms.size(); i != end; ++i) {
1892 if (eSyms[i].st_shndx == SHN_UNDEF)
1893 continue;
1894 symbols[i] = symtab.insert(CHECK(eSyms[i].getName(stringTable), this));
1895 symbols[i]->resolve(LazySymbol{*this});
1896 if (!lazy)
1897 break;
1898 }
1899}
1900
1901bool InputFile::shouldExtractForCommon(StringRef name) const {
1902 if (isa<BitcodeFile>(Val: this))
1903 return isBitcodeNonCommonDef(mb, symName: name, archiveName);
1904
1905 return isNonCommonDef(mb, symName: name, archiveName);
1906}
1907
1908std::string elf::replaceThinLTOSuffix(StringRef path) {
1909 auto [suffix, repl] = config->thinLTOObjectSuffixReplace;
1910 if (path.consume_back(Suffix: suffix))
1911 return (path + repl).str();
1912 return std::string(path);
1913}
1914
1915template class elf::ObjFile<ELF32LE>;
1916template class elf::ObjFile<ELF32BE>;
1917template class elf::ObjFile<ELF64LE>;
1918template class elf::ObjFile<ELF64BE>;
1919
1920template void SharedFile::parse<ELF32LE>();
1921template void SharedFile::parse<ELF32BE>();
1922template void SharedFile::parse<ELF64LE>();
1923template void SharedFile::parse<ELF64BE>();
1924