1//===- Config.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_CONFIG_H
10#define LLD_ELF_CONFIG_H
11
12#include "lld/Common/ErrorHandler.h"
13#include "llvm/ADT/CachedHashString.h"
14#include "llvm/ADT/DenseSet.h"
15#include "llvm/ADT/MapVector.h"
16#include "llvm/ADT/SetVector.h"
17#include "llvm/ADT/StringRef.h"
18#include "llvm/ADT/StringSet.h"
19#include "llvm/BinaryFormat/ELF.h"
20#include "llvm/Option/ArgList.h"
21#include "llvm/Support/CachePruning.h"
22#include "llvm/Support/CodeGen.h"
23#include "llvm/Support/Compiler.h"
24#include "llvm/Support/Compression.h"
25#include "llvm/Support/Endian.h"
26#include "llvm/Support/GlobPattern.h"
27#include "llvm/Support/PrettyStackTrace.h"
28#include <atomic>
29#include <memory>
30#include <optional>
31#include <vector>
32
33namespace lld::elf {
34
35class InputFile;
36class BinaryFile;
37class BitcodeFile;
38class ELFFileBase;
39class SharedFile;
40class InputSectionBase;
41class EhInputSection;
42class Symbol;
43class BitcodeCompiler;
44
45enum ELFKind : uint8_t {
46  ELFNoneKind,
47  ELF32LEKind,
48  ELF32BEKind,
49  ELF64LEKind,
50  ELF64BEKind
51};
52
53// For -Bno-symbolic, -Bsymbolic-non-weak-functions, -Bsymbolic-functions,
54// -Bsymbolic.
55enum class BsymbolicKind { None, NonWeakFunctions, Functions, All };
56
57// For --build-id.
58enum class BuildIdKind { None, Fast, Md5, Sha1, Hexstring, Uuid };
59
60// For --discard-{all,locals,none}.
61enum class DiscardPolicy { Default, All, Locals, None };
62
63// For --icf={none,safe,all}.
64enum class ICFLevel { None, Safe, All };
65
66// For --strip-{all,debug}.
67enum class StripPolicy { None, All, Debug };
68
69// For --unresolved-symbols.
70enum class UnresolvedPolicy { ReportError, Warn, Ignore };
71
72// For --orphan-handling.
73enum class OrphanHandlingPolicy { Place, Warn, Error };
74
75// For --sort-section and linkerscript sorting rules.
76enum class SortSectionPolicy { Default, None, Alignment, Name, Priority };
77
78// For --target2
79enum class Target2Policy { Abs, Rel, GotRel };
80
81// For tracking ARM Float Argument PCS
82enum class ARMVFPArgKind { Default, Base, VFP, ToolChain };
83
84// For -z noseparate-code, -z separate-code and -z separate-loadable-segments.
85enum class SeparateSegmentKind { None, Code, Loadable };
86
87// For -z *stack
88enum class GnuStackKind { None, Exec, NoExec };
89
90struct SymbolVersion {
91  llvm::StringRef name;
92  bool isExternCpp;
93  bool hasWildcard;
94};
95
96// This struct contains symbols version definition that
97// can be found in version script if it is used for link.
98struct VersionDefinition {
99  llvm::StringRef name;
100  uint16_t id;
101  SmallVector<SymbolVersion, 0> nonLocalPatterns;
102  SmallVector<SymbolVersion, 0> localPatterns;
103};
104
105class LinkerDriver {
106public:
107  void linkerMain(ArrayRef<const char *> args);
108  void addFile(StringRef path, bool withLOption);
109  void addLibrary(StringRef name);
110
111private:
112  void createFiles(llvm::opt::InputArgList &args);
113  void inferMachineType();
114  void link(llvm::opt::InputArgList &args);
115  template <class ELFT> void compileBitcodeFiles(bool skipLinkedOutput);
116
117  // True if we are in --whole-archive and --no-whole-archive.
118  bool inWholeArchive = false;
119
120  // True if we are in --start-lib and --end-lib.
121  bool inLib = false;
122
123  std::unique_ptr<BitcodeCompiler> lto;
124  std::vector<InputFile *> files;
125
126public:
127  SmallVector<std::pair<StringRef, unsigned>, 0> archiveFiles;
128};
129
130// This struct contains the global configuration for the linker.
131// Most fields are direct mapping from the command line options
132// and such fields have the same name as the corresponding options.
133// Most fields are initialized by the ctx.driver.
134struct Config {
135  uint8_t osabi = 0;
136  uint32_t andFeatures = 0;
137  llvm::CachePruningPolicy thinLTOCachePolicy;
138  llvm::SetVector<llvm::CachedHashString> dependencyFiles; // for --dependency-file
139  llvm::StringMap<uint64_t> sectionStartMap;
140  llvm::StringRef bfdname;
141  llvm::StringRef chroot;
142  llvm::StringRef dependencyFile;
143  llvm::StringRef dwoDir;
144  llvm::StringRef dynamicLinker;
145  llvm::StringRef entry;
146  llvm::StringRef emulation;
147  llvm::StringRef fini;
148  llvm::StringRef init;
149  llvm::StringRef ltoAAPipeline;
150  llvm::StringRef ltoCSProfileFile;
151  llvm::StringRef ltoNewPmPasses;
152  llvm::StringRef ltoObjPath;
153  llvm::StringRef ltoSampleProfile;
154  llvm::StringRef mapFile;
155  llvm::StringRef outputFile;
156  llvm::StringRef optRemarksFilename;
157  std::optional<uint64_t> optRemarksHotnessThreshold = 0;
158  llvm::StringRef optRemarksPasses;
159  llvm::StringRef optRemarksFormat;
160  llvm::StringRef optStatsFilename;
161  llvm::StringRef progName;
162  llvm::StringRef printArchiveStats;
163  llvm::StringRef printSymbolOrder;
164  llvm::StringRef soName;
165  llvm::StringRef sysroot;
166  llvm::StringRef thinLTOCacheDir;
167  llvm::StringRef thinLTOIndexOnlyArg;
168  llvm::StringRef whyExtract;
169  StringRef zBtiReport = "none";
170  StringRef zCetReport = "none";
171  llvm::StringRef ltoBasicBlockSections;
172  std::pair<llvm::StringRef, llvm::StringRef> thinLTOObjectSuffixReplace;
173  std::pair<llvm::StringRef, llvm::StringRef> thinLTOPrefixReplace;
174  std::string rpath;
175  llvm::SmallVector<VersionDefinition, 0> versionDefinitions;
176  llvm::SmallVector<llvm::StringRef, 0> auxiliaryList;
177  llvm::SmallVector<llvm::StringRef, 0> filterList;
178  llvm::SmallVector<llvm::StringRef, 0> passPlugins;
179  llvm::SmallVector<llvm::StringRef, 0> searchPaths;
180  llvm::SmallVector<llvm::StringRef, 0> symbolOrderingFile;
181  llvm::SmallVector<llvm::StringRef, 0> thinLTOModulesToCompile;
182  llvm::SmallVector<llvm::StringRef, 0> undefined;
183  llvm::SmallVector<SymbolVersion, 0> dynamicList;
184  llvm::SmallVector<uint8_t, 0> buildIdVector;
185  llvm::SmallVector<llvm::StringRef, 0> mllvmOpts;
186  llvm::MapVector<std::pair<const InputSectionBase *, const InputSectionBase *>,
187                  uint64_t>
188      callGraphProfile;
189  bool allowMultipleDefinition;
190  bool androidPackDynRelocs = false;
191  bool armHasBlx = false;
192  bool armHasMovtMovw = false;
193  bool armJ1J2BranchEncoding = false;
194  bool asNeeded = false;
195  BsymbolicKind bsymbolic = BsymbolicKind::None;
196  bool callGraphProfileSort;
197  bool checkSections;
198  bool checkDynamicRelocs;
199  llvm::DebugCompressionType compressDebugSections;
200  bool cref;
201  llvm::SmallVector<std::pair<llvm::GlobPattern, uint64_t>, 0>
202      deadRelocInNonAlloc;
203  bool demangle = true;
204  bool dependentLibraries;
205  bool disableVerify;
206  bool ehFrameHdr;
207  bool emitLLVM;
208  bool emitRelocs;
209  bool enableNewDtags;
210  bool executeOnly;
211  bool exportDynamic;
212  bool fixCortexA53Errata843419;
213  bool fixCortexA8;
214  bool formatBinary = false;
215  bool fortranCommon;
216  bool gcSections;
217  bool gdbIndex;
218  bool gnuHash = false;
219  bool gnuUnique;
220  bool hasDynSymTab;
221  bool ignoreDataAddressEquality;
222  bool ignoreFunctionAddressEquality;
223  bool ltoCSProfileGenerate;
224  bool ltoPGOWarnMismatch;
225  bool ltoDebugPassManager;
226  bool ltoEmitAsm;
227  bool ltoUniqueBasicBlockSectionNames;
228  bool ltoWholeProgramVisibility;
229  bool mergeArmExidx;
230  bool mipsN32Abi = false;
231  bool mmapOutputFile;
232  bool nmagic;
233  bool noDynamicLinker = false;
234  bool noinhibitExec;
235  bool nostdlib;
236  bool oFormatBinary;
237  bool omagic;
238  bool opaquePointers;
239  bool optEB = false;
240  bool optEL = false;
241  bool optimizeBBJumps;
242  bool optRemarksWithHotness;
243  bool picThunk;
244  bool pie;
245  bool printGcSections;
246  bool printIcfSections;
247  bool relax;
248  bool relocatable;
249  bool relrGlibc = false;
250  bool relrPackDynRelocs = false;
251  llvm::DenseSet<llvm::StringRef> saveTempsArgs;
252  llvm::SmallVector<std::pair<llvm::GlobPattern, uint32_t>, 0> shuffleSections;
253  bool singleRoRx;
254  bool shared;
255  bool symbolic;
256  bool isStatic = false;
257  bool sysvHash = false;
258  bool target1Rel;
259  bool trace;
260  bool thinLTOEmitImportsFiles;
261  bool thinLTOEmitIndexFiles;
262  bool thinLTOIndexOnly;
263  bool timeTraceEnabled;
264  bool tocOptimize;
265  bool pcRelOptimize;
266  bool undefinedVersion;
267  bool unique;
268  bool useAndroidRelrTags = false;
269  bool warnBackrefs;
270  llvm::SmallVector<llvm::GlobPattern, 0> warnBackrefsExclude;
271  bool warnCommon;
272  bool warnMissingEntry;
273  bool warnSymbolOrdering;
274  bool writeAddends;
275  bool zCombreloc;
276  bool zCopyreloc;
277  bool zForceBti;
278  bool zForceIbt;
279  bool zGlobal;
280  bool zHazardplt;
281  bool zIfuncNoplt;
282  bool zInitfirst;
283  bool zInterpose;
284  bool zKeepTextSectionPrefix;
285  bool zNoBtCfi;
286  bool zNodefaultlib;
287  bool zNodelete;
288  bool zNodlopen;
289  bool zNow;
290  bool zOrigin;
291  bool zPacPlt;
292  bool zRelro;
293  bool zRodynamic;
294  bool zShstk;
295  bool zStartStopGC;
296  uint8_t zStartStopVisibility;
297  bool zText;
298  bool zRetpolineplt;
299  bool zWxneeded;
300  DiscardPolicy discard;
301  GnuStackKind zGnustack;
302  ICFLevel icf;
303  OrphanHandlingPolicy orphanHandling;
304  SortSectionPolicy sortSection;
305  StripPolicy strip;
306  UnresolvedPolicy unresolvedSymbols;
307  UnresolvedPolicy unresolvedSymbolsInShlib;
308  Target2Policy target2;
309  bool power10Stubs;
310  ARMVFPArgKind armVFPArgs = ARMVFPArgKind::Default;
311  BuildIdKind buildId = BuildIdKind::None;
312  SeparateSegmentKind zSeparate;
313  ELFKind ekind = ELFNoneKind;
314  uint16_t emachine = llvm::ELF::EM_NONE;
315  std::optional<uint64_t> imageBase;
316  // commonPageSize and maxPageSize are influenced by nmagic or omagic
317  // so may be set to 1 if either of those options is given.
318  uint64_t commonPageSize;
319  uint64_t maxPageSize;
320  // textAlignPageSize is the target max page size for the purpose
321  // of aligning text sections, which may be unaligned if given nmagic
322  uint64_t textAlignPageSize;
323  uint64_t mipsGotSize;
324  uint64_t zStackSize;
325  unsigned ltoPartitions;
326  unsigned ltoo;
327  unsigned optimize;
328  StringRef thinLTOJobs;
329  unsigned timeTraceGranularity;
330  int32_t splitStackAdjustSize;
331  StringRef packageMetadata;
332
333  // The following config options do not directly correspond to any
334  // particular command line options.
335
336  // True if we need to pass through relocations in input files to the
337  // output file. Usually false because we consume relocations.
338  bool copyRelocs;
339
340  // True if the target is ELF64. False if ELF32.
341  bool is64;
342
343  // True if the target is little-endian. False if big-endian.
344  bool isLE;
345
346  // endianness::little if isLE is true. endianness::big otherwise.
347  llvm::support::endianness endianness;
348
349  // True if the target is the little-endian MIPS64.
350  //
351  // The reason why we have this variable only for the MIPS is because
352  // we use this often.  Some ELF headers for MIPS64EL are in a
353  // mixed-endian (which is horrible and I'd say that's a serious spec
354  // bug), and we need to know whether we are reading MIPS ELF files or
355  // not in various places.
356  //
357  // (Note that MIPS64EL is not a typo for MIPS64LE. This is the official
358  // name whatever that means. A fun hypothesis is that "EL" is short for
359  // little-endian written in the little-endian order, but I don't know
360  // if that's true.)
361  bool isMips64EL;
362
363  // True if we need to set the DF_STATIC_TLS flag to an output file, which
364  // works as a hint to the dynamic loader that the shared object contains code
365  // compiled with the initial-exec TLS model.
366  bool hasTlsIe = false;
367
368  // Holds set of ELF header flags for the target.
369  uint32_t eflags = 0;
370
371  // The ELF spec defines two types of relocation table entries, RELA and
372  // REL. RELA is a triplet of (offset, info, addend) while REL is a
373  // tuple of (offset, info). Addends for REL are implicit and read from
374  // the location where the relocations are applied. So, REL is more
375  // compact than RELA but requires a bit of more work to process.
376  //
377  // (From the linker writer's view, this distinction is not necessary.
378  // If the ELF had chosen whichever and sticked with it, it would have
379  // been easier to write code to process relocations, but it's too late
380  // to change the spec.)
381  //
382  // Each ABI defines its relocation type. IsRela is true if target
383  // uses RELA. As far as we know, all 64-bit ABIs are using RELA. A
384  // few 32-bit ABIs are using RELA too.
385  bool isRela;
386
387  // True if we are creating position-independent code.
388  bool isPic;
389
390  // 4 for ELF32, 8 for ELF64.
391  int wordsize;
392
393  // Mode of MTE to write to the ELF note. Should be one of NT_MEMTAG_ASYNC (for
394  // async), NT_MEMTAG_SYNC (for sync), or NT_MEMTAG_LEVEL_NONE (for none). If
395  // async or sync is enabled, write the ELF note specifying the default MTE
396  // mode.
397  int androidMemtagMode;
398  // Signal to the dynamic loader to enable heap MTE.
399  bool androidMemtagHeap;
400  // Signal to the dynamic loader that this binary expects stack MTE. Generally,
401  // this means to map the primary and thread stacks as PROT_MTE. Note: This is
402  // not supported on Android 11 & 12.
403  bool androidMemtagStack;
404
405  unsigned threadCount;
406};
407struct ConfigWrapper {
408  Config c;
409  Config *operator->() { return &c; }
410};
411
412LLVM_LIBRARY_VISIBILITY extern ConfigWrapper config;
413
414struct DuplicateSymbol {
415  const Symbol *sym;
416  const InputFile *file;
417  InputSectionBase *section;
418  uint64_t value;
419};
420
421struct Ctx {
422  LinkerDriver driver;
423  SmallVector<std::unique_ptr<MemoryBuffer>> memoryBuffers;
424  SmallVector<ELFFileBase *, 0> objectFiles;
425  SmallVector<SharedFile *, 0> sharedFiles;
426  SmallVector<BinaryFile *, 0> binaryFiles;
427  SmallVector<BitcodeFile *, 0> bitcodeFiles;
428  SmallVector<BitcodeFile *, 0> lazyBitcodeFiles;
429  SmallVector<InputSectionBase *, 0> inputSections;
430  SmallVector<EhInputSection *, 0> ehInputSections;
431  // Duplicate symbol candidates.
432  SmallVector<DuplicateSymbol, 0> duplicates;
433  // Symbols in a non-prevailing COMDAT group which should be changed to an
434  // Undefined.
435  SmallVector<std::pair<Symbol *, unsigned>, 0> nonPrevailingSyms;
436  // A tuple of (reference, extractedFile, sym). Used by --why-extract=.
437  SmallVector<std::tuple<std::string, const InputFile *, const Symbol &>, 0>
438      whyExtractRecords;
439  // A mapping from a symbol to an InputFile referencing it backward. Used by
440  // --warn-backrefs.
441  llvm::DenseMap<const Symbol *,
442                 std::pair<const InputFile *, const InputFile *>>
443      backwardReferences;
444  // True if SHT_LLVM_SYMPART is used.
445  std::atomic<bool> hasSympart{false};
446  // True if there are TLS IE relocations. Set DF_STATIC_TLS if -shared.
447  std::atomic<bool> hasTlsIe{false};
448  // True if we need to reserve two .got entries for local-dynamic TLS model.
449  std::atomic<bool> needsTlsLd{false};
450
451  void reset();
452};
453
454LLVM_LIBRARY_VISIBILITY extern Ctx ctx;
455
456// The first two elements of versionDefinitions represent VER_NDX_LOCAL and
457// VER_NDX_GLOBAL. This helper returns other elements.
458static inline ArrayRef<VersionDefinition> namedVersionDefs() {
459  return llvm::ArrayRef(config->versionDefinitions).slice(2);
460}
461
462void errorOrWarn(const Twine &msg);
463
464static inline void internalLinkerError(StringRef loc, const Twine &msg) {
465  errorOrWarn(loc + "internal linker error: " + msg + "\n" +
466              llvm::getBugReportMsg());
467}
468
469} // namespace lld::elf
470
471#endif
472