lld/ELF/Config.h

   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/SmallSet.h"
  18 #include "llvm/ADT/StringRef.h"
  19 #include "llvm/ADT/StringSet.h"
  20 #include "llvm/BinaryFormat/ELF.h"
  21 #include "llvm/Option/ArgList.h"
  22 #include "llvm/Support/CachePruning.h"
  23 #include "llvm/Support/CodeGen.h"
  24 #include "llvm/Support/Compiler.h"
  25 #include "llvm/Support/Compression.h"
  26 #include "llvm/Support/Endian.h"
  27 #include "llvm/Support/FileSystem.h"
  28 #include "llvm/Support/GlobPattern.h"
  29 #include "llvm/Support/PrettyStackTrace.h"
  30 #include <atomic>
  31 #include <memory>
  32 #include <optional>
  33 #include <vector>
  34
  35 namespace lld::elf {
  36
  37 class InputFile;
  38 class BinaryFile;
  39 class BitcodeFile;
  40 class ELFFileBase;
  41 class SharedFile;
  42 class InputSectionBase;
  43 class EhInputSection;
  44 class Symbol;
  45 class BitcodeCompiler;
  46
  47 enum ELFKind : uint8_t {
  48   ELFNoneKind,
  49   ELF32LEKind,
  50   ELF32BEKind,
  51   ELF64LEKind,
  52   ELF64BEKind
  53 };
  54
  55 // For -Bno-symbolic, -Bsymbolic-non-weak-functions, -Bsymbolic-functions,
  56 // -Bsymbolic-non-weak, -Bsymbolic.
  57 enum class BsymbolicKind { None, NonWeakFunctions, Functions, NonWeak, All };
  58
  59 // For --build-id.
  60 enum class BuildIdKind { None, Fast, Md5, Sha1, Hexstring, Uuid };
  61
  62 // For --call-graph-profile-sort={none,hfsort,cdsort}.
  63 enum class CGProfileSortKind { None, Hfsort, Cdsort };
  64
  65 // For --discard-{all,locals,none}.
  66 enum class DiscardPolicy { Default, All, Locals, None };
  67
  68 // For --icf={none,safe,all}.
  69 enum class ICFLevel { None, Safe, All };
  70
  71 // For --strip-{all,debug}.
  72 enum class StripPolicy { None, All, Debug };
  73
  74 // For --unresolved-symbols.
  75 enum class UnresolvedPolicy { ReportError, Warn, Ignore };
  76
  77 // For --orphan-handling.
  78 enum class OrphanHandlingPolicy { Place, Warn, Error };
  79
  80 // For --sort-section and linkerscript sorting rules.
  81 enum class SortSectionPolicy {
  82   Default,
  83   None,
  84   Alignment,
  85   Name,
  86   Priority,
  87   Reverse,
  88 };
  89
  90 // For --target2
  91 enum class Target2Policy { Abs, Rel, GotRel };
  92
  93 // For tracking ARM Float Argument PCS
  94 enum class ARMVFPArgKind { Default, Base, VFP, ToolChain };
  95
  96 // For -z noseparate-code, -z separate-code and -z separate-loadable-segments.
  97 enum class SeparateSegmentKind { None, Code, Loadable };
  98
  99 // For -z *stack
 100 enum class GnuStackKind { None, Exec, NoExec };
 101
 102 // For --lto=
 103 enum LtoKind : uint8_t {UnifiedThin, UnifiedRegular, Default};
 104
 105 struct SymbolVersion {
 106   llvm::StringRef name;
 107   bool isExternCpp;
 108   bool hasWildcard;
 109 };
 110
 111 // This struct contains symbols version definition that
 112 // can be found in version script if it is used for link.
 113 struct VersionDefinition {
 114   llvm::StringRef name;
 115   uint16_t id;
 116   SmallVector<SymbolVersion, 0> nonLocalPatterns;
 117   SmallVector<SymbolVersion, 0> localPatterns;
 118 };
 119
 120 class LinkerDriver {
 121 public:
 122   void linkerMain(ArrayRef<const char *> args);
 123   void addFile(StringRef path, bool withLOption);
 124   void addLibrary(StringRef name);
 125
 126 private:
 127   void createFiles(llvm::opt::InputArgList &args);
 128   void inferMachineType();
 129   void link(llvm::opt::InputArgList &args);
 130   template <class ELFT> void compileBitcodeFiles(bool skipLinkedOutput);
 131   bool tryAddFatLTOFile(MemoryBufferRef mb, StringRef archiveName,
 132                         uint64_t offsetInArchive, bool lazy);
 133   // True if we are in --whole-archive and --no-whole-archive.
 134   bool inWholeArchive = false;
 135
 136   // True if we are in --start-lib and --end-lib.
 137   bool inLib = false;
 138
 139   std::unique_ptr<BitcodeCompiler> lto;
 140   std::vector<InputFile *> files;
 141   std::optional<InputFile *> armCmseImpLib;
 142
 143 public:
 144   SmallVector<std::pair<StringRef, unsigned>, 0> archiveFiles;
 145 };
 146
 147 // This struct contains the global configuration for the linker.
 148 // Most fields are direct mapping from the command line options
 149 // and such fields have the same name as the corresponding options.
 150 // Most fields are initialized by the ctx.driver.
 151 struct Config {
 152   uint8_t osabi = 0;
 153   uint32_t andFeatures = 0;
 154   llvm::CachePruningPolicy thinLTOCachePolicy;
 155   llvm::SetVector<llvm::CachedHashString> dependencyFiles; // for --dependency-file
 156   llvm::StringMap<uint64_t> sectionStartMap;
 157   llvm::StringRef bfdname;
 158   llvm::StringRef chroot;
 159   llvm::StringRef dependencyFile;
 160   llvm::StringRef dwoDir;
 161   llvm::StringRef dynamicLinker;
 162   llvm::StringRef entry;
 163   llvm::StringRef emulation;
 164   llvm::StringRef fini;
 165   llvm::StringRef init;
 166   llvm::StringRef ltoAAPipeline;
 167   llvm::StringRef ltoCSProfileFile;
 168   llvm::StringRef ltoNewPmPasses;
 169   llvm::StringRef ltoObjPath;
 170   llvm::StringRef ltoSampleProfile;
 171   llvm::StringRef mapFile;
 172   llvm::StringRef outputFile;
 173   llvm::StringRef optRemarksFilename;
 174   std::optional<uint64_t> optRemarksHotnessThreshold = 0;
 175   llvm::StringRef optRemarksPasses;
 176   llvm::StringRef optRemarksFormat;
 177   llvm::StringRef optStatsFilename;
 178   llvm::StringRef progName;
 179   llvm::StringRef printArchiveStats;
 180   llvm::StringRef printSymbolOrder;
 181   llvm::StringRef soName;
 182   llvm::StringRef sysroot;
 183   llvm::StringRef thinLTOCacheDir;
 184   llvm::StringRef thinLTOIndexOnlyArg;
 185   llvm::StringRef whyExtract;
 186   llvm::StringRef cmseInputLib;
 187   llvm::StringRef cmseOutputLib;
 188   StringRef zBtiReport = "none";
 189   StringRef zCetReport = "none";
 190   llvm::StringRef ltoBasicBlockSections;
 191   std::pair<llvm::StringRef, llvm::StringRef> thinLTOObjectSuffixReplace;
 192   llvm::StringRef thinLTOPrefixReplaceOld;
 193   llvm::StringRef thinLTOPrefixReplaceNew;
 194   llvm::StringRef thinLTOPrefixReplaceNativeObject;
 195   std::string rpath;
 196   llvm::SmallVector<VersionDefinition, 0> versionDefinitions;
 197   llvm::SmallVector<llvm::StringRef, 0> auxiliaryList;
 198   llvm::SmallVector<llvm::StringRef, 0> filterList;
 199   llvm::SmallVector<llvm::StringRef, 0> passPlugins;
 200   llvm::SmallVector<llvm::StringRef, 0> searchPaths;
 201   llvm::SmallVector<llvm::StringRef, 0> symbolOrderingFile;
 202   llvm::SmallVector<llvm::StringRef, 0> thinLTOModulesToCompile;
 203   llvm::SmallVector<llvm::StringRef, 0> undefined;
 204   llvm::SmallVector<SymbolVersion, 0> dynamicList;
 205   llvm::SmallVector<uint8_t, 0> buildIdVector;
 206   llvm::SmallVector<llvm::StringRef, 0> mllvmOpts;
 207   llvm::MapVector<std::pair<const InputSectionBase *, const InputSectionBase *>,
 208                   uint64_t>
 209       callGraphProfile;
 210   bool cmseImplib = false;
 211   bool allowMultipleDefinition;
 212   bool fatLTOObjects;
 213   bool androidPackDynRelocs = false;
 214   bool armHasBlx = false;
 215   bool armHasMovtMovw = false;
 216   bool armJ1J2BranchEncoding = false;
 217   bool armCMSESupport = false;
 218   bool asNeeded = false;
 219   bool armBe8 = false;
 220   BsymbolicKind bsymbolic = BsymbolicKind::None;
 221   CGProfileSortKind callGraphProfileSort;
 222   bool checkSections;
 223   bool checkDynamicRelocs;
 224   llvm::DebugCompressionType compressDebugSections;
 225   bool cref;
 226   llvm::SmallVector<std::pair<llvm::GlobPattern, uint64_t>, 0>
 227       deadRelocInNonAlloc;
 228   bool demangle = true;
 229   bool dependentLibraries;
 230   bool disableVerify;
 231   bool ehFrameHdr;
 232   bool emitLLVM;
 233   bool emitRelocs;
 234   bool enableNewDtags;
 235   bool executeOnly;
 236   bool exportDynamic;
 237   bool fixCortexA53Errata843419;
 238   bool fixCortexA8;
 239   bool formatBinary = false;
 240   bool fortranCommon;
 241   bool gcSections;
 242   bool gdbIndex;
 243   bool gnuHash = false;
 244   bool gnuUnique;
 245   bool hasDynSymTab;
 246   bool ignoreDataAddressEquality;
 247   bool ignoreFunctionAddressEquality;
 248   bool ltoCSProfileGenerate;
 249   bool ltoPGOWarnMismatch;
 250   bool ltoDebugPassManager;
 251   bool ltoEmitAsm;
 252   bool ltoUniqueBasicBlockSectionNames;
 253   bool ltoValidateAllVtablesHaveTypeInfos;
 254   bool ltoWholeProgramVisibility;
 255   bool mergeArmExidx;
 256   bool mipsN32Abi = false;
 257   bool mmapOutputFile;
 258   bool nmagic;
 259   bool noDynamicLinker = false;
 260   bool noinhibitExec;
 261   bool nostdlib;
 262   bool oFormatBinary;
 263   bool omagic;
 264   bool optEB = false;
 265   bool optEL = false;
 266   bool optimizeBBJumps;
 267   bool optRemarksWithHotness;
 268   bool picThunk;
 269   bool pie;
 270   bool printGcSections;
 271   bool printIcfSections;
 272   bool printMemoryUsage;
 273   bool relax;
 274   bool relaxGP;
 275   bool relocatable;
 276   bool relrGlibc = false;
 277   bool relrPackDynRelocs = false;
 278   llvm::DenseSet<llvm::StringRef> saveTempsArgs;
 279   llvm::SmallVector<std::pair<llvm::GlobPattern, uint32_t>, 0> shuffleSections;
 280   bool singleRoRx;
 281   bool shared;
 282   bool symbolic;
 283   bool isStatic = false;
 284   bool sysvHash = false;
 285   bool target1Rel;
 286   bool trace;
 287   bool thinLTOEmitImportsFiles;
 288   bool thinLTOEmitIndexFiles;
 289   bool thinLTOIndexOnly;
 290   bool timeTraceEnabled;
 291   bool tocOptimize;
 292   bool pcRelOptimize;
 293   bool undefinedVersion;
 294   bool unique;
 295   bool useAndroidRelrTags = false;
 296   bool warnBackrefs;
 297   llvm::SmallVector<llvm::GlobPattern, 0> warnBackrefsExclude;
 298   bool warnCommon;
 299   bool warnMissingEntry;
 300   bool warnSymbolOrdering;
 301   bool writeAddends;
 302   bool zCombreloc;
 303   bool zCopyreloc;
 304   bool zForceBti;
 305   bool zForceIbt;
 306   bool zGlobal;
 307   bool zHazardplt;
 308   bool zIfuncNoplt;
 309   bool zInitfirst;
 310   bool zInterpose;
 311   bool zKeepTextSectionPrefix;
 312   bool zNodefaultlib;
 313   bool zNodelete;
 314   bool zNodlopen;
 315   bool zNow;
 316   bool zOrigin;
 317   bool zPacPlt;
 318   bool zRelro;
 319   bool zRodynamic;
 320   bool zShstk;
 321   bool zStartStopGC;
 322   uint8_t zStartStopVisibility;
 323   bool zText;
 324   bool zRetpolineplt;
 325   bool zWxneeded;
 326   DiscardPolicy discard;
 327   GnuStackKind zGnustack;
 328   ICFLevel icf;
 329   OrphanHandlingPolicy orphanHandling;
 330   SortSectionPolicy sortSection;
 331   StripPolicy strip;
 332   UnresolvedPolicy unresolvedSymbols;
 333   UnresolvedPolicy unresolvedSymbolsInShlib;
 334   Target2Policy target2;
 335   bool power10Stubs;
 336   ARMVFPArgKind armVFPArgs = ARMVFPArgKind::Default;
 337   BuildIdKind buildId = BuildIdKind::None;
 338   SeparateSegmentKind zSeparate;
 339   ELFKind ekind = ELFNoneKind;
 340   uint16_t emachine = llvm::ELF::EM_NONE;
 341   std::optional<uint64_t> imageBase;
 342   uint64_t commonPageSize;
 343   uint64_t maxPageSize;
 344   uint64_t mipsGotSize;
 345   uint64_t zStackSize;
 346   unsigned ltoPartitions;
 347   unsigned ltoo;
 348   llvm::CodeGenOptLevel ltoCgo;
 349   unsigned optimize;
 350   StringRef thinLTOJobs;
 351   unsigned timeTraceGranularity;
 352   int32_t splitStackAdjustSize;
 353   StringRef packageMetadata;
 354
 355   // The following config options do not directly correspond to any
 356   // particular command line options.
 357
 358   // True if we need to pass through relocations in input files to the
 359   // output file. Usually false because we consume relocations.
 360   bool copyRelocs;
 361
 362   // True if the target is ELF64. False if ELF32.
 363   bool is64;
 364
 365   // True if the target is little-endian. False if big-endian.
 366   bool isLE;
 367
 368   // endianness::little if isLE is true. endianness::big otherwise.
 369   llvm::endianness endianness;
 370
 371   // True if the target is the little-endian MIPS64.
 372   //
 373   // The reason why we have this variable only for the MIPS is because
 374   // we use this often.  Some ELF headers for MIPS64EL are in a
 375   // mixed-endian (which is horrible and I'd say that's a serious spec
 376   // bug), and we need to know whether we are reading MIPS ELF files or
 377   // not in various places.
 378   //
 379   // (Note that MIPS64EL is not a typo for MIPS64LE. This is the official
 380   // name whatever that means. A fun hypothesis is that "EL" is short for
 381   // little-endian written in the little-endian order, but I don't know
 382   // if that's true.)
 383   bool isMips64EL;
 384
 385   // True if we need to set the DF_STATIC_TLS flag to an output file, which
 386   // works as a hint to the dynamic loader that the shared object contains code
 387   // compiled with the initial-exec TLS model.
 388   bool hasTlsIe = false;
 389
 390   // Holds set of ELF header flags for the target.
 391   uint32_t eflags = 0;
 392
 393   // The ELF spec defines two types of relocation table entries, RELA and
 394   // REL. RELA is a triplet of (offset, info, addend) while REL is a
 395   // tuple of (offset, info). Addends for REL are implicit and read from
 396   // the location where the relocations are applied. So, REL is more
 397   // compact than RELA but requires a bit of more work to process.
 398   //
 399   // (From the linker writer's view, this distinction is not necessary.
 400   // If the ELF had chosen whichever and sticked with it, it would have
 401   // been easier to write code to process relocations, but it's too late
 402   // to change the spec.)
 403   //
 404   // Each ABI defines its relocation type. IsRela is true if target
 405   // uses RELA. As far as we know, all 64-bit ABIs are using RELA. A
 406   // few 32-bit ABIs are using RELA too.
 407   bool isRela;
 408
 409   // True if we are creating position-independent code.
 410   bool isPic;
 411
 412   // 4 for ELF32, 8 for ELF64.
 413   int wordsize;
 414
 415   // Mode of MTE to write to the ELF note. Should be one of NT_MEMTAG_ASYNC (for
 416   // async), NT_MEMTAG_SYNC (for sync), or NT_MEMTAG_LEVEL_NONE (for none). If
 417   // async or sync is enabled, write the ELF note specifying the default MTE
 418   // mode.
 419   int androidMemtagMode;
 420   // Signal to the dynamic loader to enable heap MTE.
 421   bool androidMemtagHeap;
 422   // Signal to the dynamic loader that this binary expects stack MTE. Generally,
 423   // this means to map the primary and thread stacks as PROT_MTE. Note: This is
 424   // not supported on Android 11 & 12.
 425   bool androidMemtagStack;
 426
 427   // When using a unified pre-link LTO pipeline, specify the backend LTO mode.
 428   LtoKind ltoKind = LtoKind::Default;
 429
 430   unsigned threadCount;
 431
 432   // If an input file equals a key, remap it to the value.
 433   llvm::DenseMap<llvm::StringRef, llvm::StringRef> remapInputs;
 434   // If an input file matches a wildcard pattern, remap it to the value.
 435   llvm::SmallVector<std::pair<llvm::GlobPattern, llvm::StringRef>, 0>
 436       remapInputsWildcards;
 437 };
 438 struct ConfigWrapper {
 439   Config c;
 440   Config *operator->() { return &c; }
 441 };
 442
 443 LLVM_LIBRARY_VISIBILITY extern ConfigWrapper config;
 444
 445 struct DuplicateSymbol {
 446   const Symbol *sym;
 447   const InputFile *file;
 448   InputSectionBase *section;
 449   uint64_t value;
 450 };
 451
 452 struct Ctx {
 453   LinkerDriver driver;
 454   SmallVector<std::unique_ptr<MemoryBuffer>> memoryBuffers;
 455   SmallVector<ELFFileBase *, 0> objectFiles;
 456   SmallVector<SharedFile *, 0> sharedFiles;
 457   SmallVector<BinaryFile *, 0> binaryFiles;
 458   SmallVector<BitcodeFile *, 0> bitcodeFiles;
 459   SmallVector<BitcodeFile *, 0> lazyBitcodeFiles;
 460   SmallVector<InputSectionBase *, 0> inputSections;
 461   SmallVector<EhInputSection *, 0> ehInputSections;
 462   // Duplicate symbol candidates.
 463   SmallVector<DuplicateSymbol, 0> duplicates;
 464   // Symbols in a non-prevailing COMDAT group which should be changed to an
 465   // Undefined.
 466   SmallVector<std::pair<Symbol *, unsigned>, 0> nonPrevailingSyms;
 467   // A tuple of (reference, extractedFile, sym). Used by --why-extract=.
 468   SmallVector<std::tuple<std::string, const InputFile *, const Symbol &>, 0>
 469       whyExtractRecords;
 470   // A mapping from a symbol to an InputFile referencing it backward. Used by
 471   // --warn-backrefs.
 472   llvm::DenseMap<const Symbol *,
 473                  std::pair<const InputFile *, const InputFile *>>
 474       backwardReferences;
 475   llvm::SmallSet<llvm::StringRef, 0> auxiliaryFiles;
 476   // True if SHT_LLVM_SYMPART is used.
 477   std::atomic<bool> hasSympart{false};
 478   // True if there are TLS IE relocations. Set DF_STATIC_TLS if -shared.
 479   std::atomic<bool> hasTlsIe{false};
 480   // True if we need to reserve two .got entries for local-dynamic TLS model.
 481   std::atomic<bool> needsTlsLd{false};
 482   // True if all native vtable symbols have corresponding type info symbols
 483   // during LTO.
 484   bool ltoAllVtablesHaveTypeInfos;
 485
 486   // Each symbol assignment and DEFINED(sym) reference is assigned an increasing
 487   // order. Each DEFINED(sym) evaluation checks whether the reference happens
 488   // before a possible `sym = expr;`.
 489   unsigned scriptSymOrderCounter = 1;
 490   llvm::DenseMap<const Symbol *, unsigned> scriptSymOrder;
 491
 492   void reset();
 493
 494   llvm::raw_fd_ostream openAuxiliaryFile(llvm::StringRef, std::error_code &);
 495 };
 496
 497 LLVM_LIBRARY_VISIBILITY extern Ctx ctx;
 498
 499 // The first two elements of versionDefinitions represent VER_NDX_LOCAL and
 500 // VER_NDX_GLOBAL. This helper returns other elements.
 501 static inline ArrayRef<VersionDefinition> namedVersionDefs() {
 502   return llvm::ArrayRef(config->versionDefinitions).slice(2);
 503 }
 504
 505 void errorOrWarn(const Twine &msg);
 506
 507 static inline void internalLinkerError(StringRef loc, const Twine &msg) {
 508   errorOrWarn(loc + "internal linker error: " + msg + "\n" +
 509               llvm::getBugReportMsg());
 510 }
 511
 512 } // namespace lld::elf
 513
 514 #endif