1//===- InputFiles.h ---------------------------------------------*- C++ -*-===//
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#ifndef LLD_ELF_INPUT_FILES_H
10#define LLD_ELF_INPUT_FILES_H
11
12#include "Config.h"
13#include "Symbols.h"
14#include "lld/Common/ErrorHandler.h"
15#include "lld/Common/LLVM.h"
16#include "lld/Common/Reproduce.h"
17#include "llvm/ADT/DenseSet.h"
18#include "llvm/BinaryFormat/Magic.h"
19#include "llvm/Object/ELF.h"
20#include "llvm/Support/MemoryBufferRef.h"
21#include "llvm/Support/Threading.h"
22
23namespace llvm {
24struct DILineInfo;
25class TarWriter;
26namespace lto {
27class InputFile;
28}
29} // namespace llvm
30
31namespace lld {
32class DWARFCache;
33
34// Returns "<internal>", "foo.a(bar.o)" or "baz.o".
35std::string toString(const elf::InputFile *f);
36
37namespace elf {
38
39class InputSection;
40class Symbol;
41
42// If --reproduce is specified, all input files are written to this tar archive.
43extern std::unique_ptr<llvm::TarWriter> tar;
44
45// Opens a given file.
46std::optional<MemoryBufferRef> readFile(StringRef path);
47
48// Add symbols in File to the symbol table.
49void parseFile(InputFile *file);
50
51void parseArmCMSEImportLib(InputFile *file);
52
53// The root class of input files.
54class InputFile {
55protected:
56 std::unique_ptr<Symbol *[]> symbols;
57 uint32_t numSymbols = 0;
58 SmallVector<InputSectionBase *, 0> sections;
59
60public:
61 enum Kind : uint8_t {
62 ObjKind,
63 SharedKind,
64 BitcodeKind,
65 BinaryKind,
66 InternalKind,
67 };
68
69 InputFile(Kind k, MemoryBufferRef m);
70 Kind kind() const { return fileKind; }
71
72 bool isElf() const {
73 Kind k = kind();
74 return k == ObjKind || k == SharedKind;
75 }
76 bool isInternal() const { return kind() == InternalKind; }
77
78 StringRef getName() const { return mb.getBufferIdentifier(); }
79 MemoryBufferRef mb;
80
81 // Returns sections. It is a runtime error to call this function
82 // on files that don't have the notion of sections.
83 ArrayRef<InputSectionBase *> getSections() const {
84 assert(fileKind == ObjKind || fileKind == BinaryKind);
85 return sections;
86 }
87
88 // Returns object file symbols. It is a runtime error to call this
89 // function on files of other types.
90 ArrayRef<Symbol *> getSymbols() const {
91 assert(fileKind == BinaryKind || fileKind == ObjKind ||
92 fileKind == BitcodeKind);
93 return {symbols.get(), numSymbols};
94 }
95
96 MutableArrayRef<Symbol *> getMutableSymbols() {
97 assert(fileKind == BinaryKind || fileKind == ObjKind ||
98 fileKind == BitcodeKind);
99 return {symbols.get(), numSymbols};
100 }
101
102 // Get filename to use for linker script processing.
103 StringRef getNameForScript() const;
104
105 // Check if a non-common symbol should be extracted to override a common
106 // definition.
107 bool shouldExtractForCommon(StringRef name) const;
108
109 // .got2 in the current file. This is used by PPC32 -fPIC/-fPIE to compute
110 // offsets in PLT call stubs.
111 InputSection *ppc32Got2 = nullptr;
112
113 // Index of MIPS GOT built for this file.
114 uint32_t mipsGotIndex = -1;
115
116 // groupId is used for --warn-backrefs which is an optional error
117 // checking feature. All files within the same --{start,end}-group or
118 // --{start,end}-lib get the same group ID. Otherwise, each file gets a new
119 // group ID. For more info, see checkDependency() in SymbolTable.cpp.
120 uint32_t groupId;
121 static bool isInGroup;
122 static uint32_t nextGroupId;
123
124 // If this is an architecture-specific file, the following members
125 // have ELF type (i.e. ELF{32,64}{LE,BE}) and target machine type.
126 uint16_t emachine = llvm::ELF::EM_NONE;
127 const Kind fileKind;
128 ELFKind ekind = ELFNoneKind;
129 uint8_t osabi = 0;
130 uint8_t abiVersion = 0;
131
132 // True if this is a relocatable object file/bitcode file in an ar archive
133 // or between --start-lib and --end-lib.
134 bool lazy = false;
135
136 // True if this is an argument for --just-symbols. Usually false.
137 bool justSymbols = false;
138
139 std::string getSrcMsg(const Symbol &sym, const InputSectionBase &sec,
140 uint64_t offset);
141
142 // On PPC64 we need to keep track of which files contain small code model
143 // relocations that access the .toc section. To minimize the chance of a
144 // relocation overflow, files that do contain said relocations should have
145 // their .toc sections sorted closer to the .got section than files that do
146 // not contain any small code model relocations. Thats because the toc-pointer
147 // is defined to point at .got + 0x8000 and the instructions used with small
148 // code model relocations support immediates in the range [-0x8000, 0x7FFC],
149 // making the addressable range relative to the toc pointer
150 // [.got, .got + 0xFFFC].
151 bool ppc64SmallCodeModelTocRelocs = false;
152
153 // True if the file has TLSGD/TLSLD GOT relocations without R_PPC64_TLSGD or
154 // R_PPC64_TLSLD. Disable TLS relaxation to avoid bad code generation.
155 bool ppc64DisableTLSRelax = false;
156
157public:
158 // If not empty, this stores the name of the archive containing this file.
159 // We use this string for creating error messages.
160 SmallString<0> archiveName;
161 // Cache for toString(). Only toString() should use this member.
162 mutable SmallString<0> toStringCache;
163
164private:
165 // Cache for getNameForScript().
166 mutable SmallString<0> nameForScriptCache;
167};
168
169class ELFFileBase : public InputFile {
170public:
171 ELFFileBase(Kind k, ELFKind ekind, MemoryBufferRef m);
172 static bool classof(const InputFile *f) { return f->isElf(); }
173
174 void init();
175 template <typename ELFT> llvm::object::ELFFile<ELFT> getObj() const {
176 return check(llvm::object::ELFFile<ELFT>::create(mb.getBuffer()));
177 }
178
179 StringRef getStringTable() const { return stringTable; }
180
181 ArrayRef<Symbol *> getLocalSymbols() {
182 if (numSymbols == 0)
183 return {};
184 return llvm::ArrayRef(symbols.get() + 1, firstGlobal - 1);
185 }
186 ArrayRef<Symbol *> getGlobalSymbols() {
187 return llvm::ArrayRef(symbols.get() + firstGlobal,
188 numSymbols - firstGlobal);
189 }
190 MutableArrayRef<Symbol *> getMutableGlobalSymbols() {
191 return llvm::MutableArrayRef(symbols.get() + firstGlobal,
192 numSymbols - firstGlobal);
193 }
194
195 template <typename ELFT> typename ELFT::ShdrRange getELFShdrs() const {
196 return typename ELFT::ShdrRange(
197 reinterpret_cast<const typename ELFT::Shdr *>(elfShdrs), numELFShdrs);
198 }
199 template <typename ELFT> typename ELFT::SymRange getELFSyms() const {
200 return typename ELFT::SymRange(
201 reinterpret_cast<const typename ELFT::Sym *>(elfSyms), numELFSyms);
202 }
203 template <typename ELFT> typename ELFT::SymRange getGlobalELFSyms() const {
204 return getELFSyms<ELFT>().slice(firstGlobal);
205 }
206
207protected:
208 // Initializes this class's member variables.
209 template <typename ELFT> void init(InputFile::Kind k);
210
211 StringRef stringTable;
212 const void *elfShdrs = nullptr;
213 const void *elfSyms = nullptr;
214 uint32_t numELFShdrs = 0;
215 uint32_t numELFSyms = 0;
216 uint32_t firstGlobal = 0;
217
218public:
219 uint32_t andFeatures = 0;
220 bool hasCommonSyms = false;
221};
222
223// .o file.
224template <class ELFT> class ObjFile : public ELFFileBase {
225 LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
226
227public:
228 static bool classof(const InputFile *f) { return f->kind() == ObjKind; }
229
230 llvm::object::ELFFile<ELFT> getObj() const {
231 return this->ELFFileBase::getObj<ELFT>();
232 }
233
234 ObjFile(ELFKind ekind, MemoryBufferRef m, StringRef archiveName)
235 : ELFFileBase(ObjKind, ekind, m) {
236 this->archiveName = archiveName;
237 }
238
239 void parse(bool ignoreComdats = false);
240 void parseLazy();
241
242 StringRef getShtGroupSignature(ArrayRef<Elf_Shdr> sections,
243 const Elf_Shdr &sec);
244
245 Symbol &getSymbol(uint32_t symbolIndex) const {
246 if (symbolIndex >= numSymbols)
247 fatal(toString(this) + ": invalid symbol index");
248 return *this->symbols[symbolIndex];
249 }
250
251 uint32_t getSectionIndex(const Elf_Sym &sym) const;
252
253 template <typename RelT> Symbol &getRelocTargetSym(const RelT &rel) const {
254 uint32_t symIndex = rel.getSymbol(config->isMips64EL);
255 return getSymbol(symbolIndex: symIndex);
256 }
257
258 std::optional<llvm::DILineInfo> getDILineInfo(const InputSectionBase *,
259 uint64_t);
260 std::optional<std::pair<std::string, unsigned>>
261 getVariableLoc(StringRef name);
262
263 // Name of source file obtained from STT_FILE symbol value,
264 // or empty string if there is no such symbol in object file
265 // symbol table.
266 StringRef sourceFile;
267
268 // Pointer to this input file's .llvm_addrsig section, if it has one.
269 const Elf_Shdr *addrsigSec = nullptr;
270
271 // SHT_LLVM_CALL_GRAPH_PROFILE section index.
272 uint32_t cgProfileSectionIndex = 0;
273
274 // MIPS GP0 value defined by this file. This value represents the gp value
275 // used to create the relocatable object and required to support
276 // R_MIPS_GPREL16 / R_MIPS_GPREL32 relocations.
277 uint32_t mipsGp0 = 0;
278
279 // True if the file defines functions compiled with
280 // -fsplit-stack. Usually false.
281 bool splitStack = false;
282
283 // True if the file defines functions compiled with -fsplit-stack,
284 // but had one or more functions with the no_split_stack attribute.
285 bool someNoSplitStack = false;
286
287 // Get cached DWARF information.
288 DWARFCache *getDwarf();
289
290 void initSectionsAndLocalSyms(bool ignoreComdats);
291 void postParse();
292 void importCmseSymbols();
293
294private:
295 void initializeSections(bool ignoreComdats,
296 const llvm::object::ELFFile<ELFT> &obj);
297 void initializeSymbols(const llvm::object::ELFFile<ELFT> &obj);
298 void initializeJustSymbols();
299
300 InputSectionBase *getRelocTarget(uint32_t idx, const Elf_Shdr &sec,
301 uint32_t info);
302 InputSectionBase *createInputSection(uint32_t idx, const Elf_Shdr &sec,
303 StringRef name);
304
305 bool shouldMerge(const Elf_Shdr &sec, StringRef name);
306
307 // Each ELF symbol contains a section index which the symbol belongs to.
308 // However, because the number of bits dedicated for that is limited, a
309 // symbol can directly point to a section only when the section index is
310 // equal to or smaller than 65280.
311 //
312 // If an object file contains more than 65280 sections, the file must
313 // contain .symtab_shndx section. The section contains an array of
314 // 32-bit integers whose size is the same as the number of symbols.
315 // Nth symbol's section index is in the Nth entry of .symtab_shndx.
316 //
317 // The following variable contains the contents of .symtab_shndx.
318 // If the section does not exist (which is common), the array is empty.
319 ArrayRef<Elf_Word> shndxTable;
320
321 // Debugging information to retrieve source file and line for error
322 // reporting. Linker may find reasonable number of errors in a
323 // single object file, so we cache debugging information in order to
324 // parse it only once for each object file we link.
325 std::unique_ptr<DWARFCache> dwarf;
326 llvm::once_flag initDwarf;
327};
328
329class BitcodeFile : public InputFile {
330public:
331 BitcodeFile(MemoryBufferRef m, StringRef archiveName,
332 uint64_t offsetInArchive, bool lazy);
333 static bool classof(const InputFile *f) { return f->kind() == BitcodeKind; }
334 void parse();
335 void parseLazy();
336 void postParse();
337 std::unique_ptr<llvm::lto::InputFile> obj;
338 std::vector<bool> keptComdats;
339};
340
341// .so file.
342class SharedFile : public ELFFileBase {
343public:
344 SharedFile(MemoryBufferRef m, StringRef defaultSoName);
345
346 // This is actually a vector of Elf_Verdef pointers.
347 SmallVector<const void *, 0> verdefs;
348
349 // If the output file needs Elf_Verneed data structures for this file, this is
350 // a vector of Elf_Vernaux version identifiers that map onto the entries in
351 // Verdefs, otherwise it is empty.
352 SmallVector<uint32_t, 0> vernauxs;
353
354 static unsigned vernauxNum;
355
356 SmallVector<StringRef, 0> dtNeeded;
357 StringRef soName;
358
359 static bool classof(const InputFile *f) { return f->kind() == SharedKind; }
360
361 template <typename ELFT> void parse();
362
363 // Used for --as-needed
364 bool isNeeded;
365
366 // Non-weak undefined symbols which are not yet resolved when the SO is
367 // parsed. Only filled for `--no-allow-shlib-undefined`.
368 SmallVector<Symbol *, 0> requiredSymbols;
369
370private:
371 template <typename ELFT>
372 std::vector<uint32_t> parseVerneed(const llvm::object::ELFFile<ELFT> &obj,
373 const typename ELFT::Shdr *sec);
374};
375
376class BinaryFile : public InputFile {
377public:
378 explicit BinaryFile(MemoryBufferRef m) : InputFile(BinaryKind, m) {}
379 static bool classof(const InputFile *f) { return f->kind() == BinaryKind; }
380 void parse();
381};
382
383InputFile *createInternalFile(StringRef name);
384ELFFileBase *createObjFile(MemoryBufferRef mb, StringRef archiveName = "",
385 bool lazy = false);
386
387std::string replaceThinLTOSuffix(StringRef path);
388
389} // namespace elf
390} // namespace lld
391
392#endif
393

source code of lld/ELF/InputFiles.h