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/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
  33 namespace lld::elf {
  34
  35 class InputFile;
  36 class BinaryFile;
  37 class BitcodeFile;
  38 class ELFFileBase;
  39 class SharedFile;
  40 class InputSectionBase;
  41 class EhInputSection;
  42 class Symbol;
  43 class BitcodeCompiler;
  44
  45 enum 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.
  55 enum class BsymbolicKind { None, NonWeakFunctions, Functions, All };
  56
  57 // For --build-id.
  58 enum class BuildIdKind { None, Fast, Md5, Sha1, Hexstring, Uuid };
  59
  60 // For --discard-{all,locals,none}.
  61 enum class DiscardPolicy { Default, All, Locals, None };
  62
  63 // For --icf={none,safe,all}.
  64 enum class ICFLevel { None, Safe, All };
  65
  66 // For --strip-{all,debug}.
  67 enum class StripPolicy { None, All, Debug };
  68
  69 // For --unresolved-symbols.
  70 enum class UnresolvedPolicy { ReportError, Warn, Ignore };
  71
  72 // For --orphan-handling.
  73 enum class OrphanHandlingPolicy { Place, Warn, Error };
  74
  75 // For --sort-section and linkerscript sorting rules.
  76 enum class SortSectionPolicy { Default, None, Alignment, Name, Priority };
  77
  78 // For --target2
  79 enum class Target2Policy { Abs, Rel, GotRel };
  80
  81 // For tracking ARM Float Argument PCS
  82 enum class ARMVFPArgKind { Default, Base, VFP, ToolChain };
  83
  84 // For -z noseparate-code, -z separate-code and -z separate-loadable-segments.
  85 enum class SeparateSegmentKind { None, Code, Loadable };
  86
  87 // For -z *stack
  88 enum class GnuStackKind { None, Exec, NoExec };
  89
  90 struct 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.
  98 struct VersionDefinition {
  99   llvm::StringRef name;
 100   uint16_t id;
 101   SmallVector<SymbolVersion, 0> nonLocalPatterns;
 102   SmallVector<SymbolVersion, 0> localPatterns;
 103 };
 104
 105 class LinkerDriver {
 106 public:
 107   void linkerMain(ArrayRef<const char *> args);
 108   void addFile(StringRef path, bool withLOption);
 109   void addLibrary(StringRef name);
 110
 111 private:
 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
 126 public:
 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.
 134 struct 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 optEB = false;
 239   bool optEL = false;
 240   bool optimizeBBJumps;
 241   bool optRemarksWithHotness;
 242   bool picThunk;
 243   bool pie;
 244   bool printGcSections;
 245   bool printIcfSections;
 246   bool relax;
 247   bool relocatable;
 248   bool relrGlibc = false;
 249   bool relrPackDynRelocs = false;
 250   llvm::DenseSet<llvm::StringRef> saveTempsArgs;
 251   llvm::SmallVector<std::pair<llvm::GlobPattern, uint32_t>, 0> shuffleSections;
 252   bool singleRoRx;
 253   bool shared;
 254   bool symbolic;
 255   bool isStatic = false;
 256   bool sysvHash = false;
 257   bool target1Rel;
 258   bool trace;
 259   bool thinLTOEmitImportsFiles;
 260   bool thinLTOEmitIndexFiles;
 261   bool thinLTOIndexOnly;
 262   bool timeTraceEnabled;
 263   bool tocOptimize;
 264   bool pcRelOptimize;
 265   bool undefinedVersion;
 266   bool unique;
 267   bool useAndroidRelrTags = false;
 268   bool warnBackrefs;
 269   llvm::SmallVector<llvm::GlobPattern, 0> warnBackrefsExclude;
 270   bool warnCommon;
 271   bool warnMissingEntry;
 272   bool warnSymbolOrdering;
 273   bool writeAddends;
 274   bool zCombreloc;
 275   bool zCopyreloc;
 276   bool zForceBti;
 277   bool zForceIbt;
 278   bool zGlobal;
 279   bool zHazardplt;
 280   bool zIfuncNoplt;
 281   bool zInitfirst;
 282   bool zInterpose;
 283   bool zKeepTextSectionPrefix;
 284   bool zNodefaultlib;
 285   bool zNodelete;
 286   bool zNodlopen;
 287   bool zNow;
 288   bool zOrigin;
 289   bool zPacPlt;
 290   bool zRelro;
 291   bool zRodynamic;
 292   bool zShstk;
 293   bool zStartStopGC;
 294   uint8_t zStartStopVisibility;
 295   bool zText;
 296   bool zRetpolineplt;
 297   bool zWxneeded;
 298   DiscardPolicy discard;
 299   GnuStackKind zGnustack;
 300   ICFLevel icf;
 301   OrphanHandlingPolicy orphanHandling;
 302   SortSectionPolicy sortSection;
 303   StripPolicy strip;
 304   UnresolvedPolicy unresolvedSymbols;
 305   UnresolvedPolicy unresolvedSymbolsInShlib;
 306   Target2Policy target2;
 307   bool power10Stubs;
 308   ARMVFPArgKind armVFPArgs = ARMVFPArgKind::Default;
 309   BuildIdKind buildId = BuildIdKind::None;
 310   SeparateSegmentKind zSeparate;
 311   ELFKind ekind = ELFNoneKind;
 312   uint16_t emachine = llvm::ELF::EM_NONE;
 313   std::optional<uint64_t> imageBase;
 314   uint64_t commonPageSize;
 315   uint64_t maxPageSize;
 316   uint64_t mipsGotSize;
 317   uint64_t zStackSize;
 318   unsigned ltoPartitions;
 319   unsigned ltoo;
 320   unsigned optimize;
 321   StringRef thinLTOJobs;
 322   unsigned timeTraceGranularity;
 323   int32_t splitStackAdjustSize;
 324   StringRef packageMetadata;
 325
 326   // The following config options do not directly correspond to any
 327   // particular command line options.
 328
 329   // True if we need to pass through relocations in input files to the
 330   // output file. Usually false because we consume relocations.
 331   bool copyRelocs;
 332
 333   // True if the target is ELF64. False if ELF32.
 334   bool is64;
 335
 336   // True if the target is little-endian. False if big-endian.
 337   bool isLE;
 338
 339   // endianness::little if isLE is true. endianness::big otherwise.
 340   llvm::support::endianness endianness;
 341
 342   // True if the target is the little-endian MIPS64.
 343   //
 344   // The reason why we have this variable only for the MIPS is because
 345   // we use this often.  Some ELF headers for MIPS64EL are in a
 346   // mixed-endian (which is horrible and I'd say that's a serious spec
 347   // bug), and we need to know whether we are reading MIPS ELF files or
 348   // not in various places.
 349   //
 350   // (Note that MIPS64EL is not a typo for MIPS64LE. This is the official
 351   // name whatever that means. A fun hypothesis is that "EL" is short for
 352   // little-endian written in the little-endian order, but I don't know
 353   // if that's true.)
 354   bool isMips64EL;
 355
 356   // True if we need to set the DF_STATIC_TLS flag to an output file, which
 357   // works as a hint to the dynamic loader that the shared object contains code
 358   // compiled with the initial-exec TLS model.
 359   bool hasTlsIe = false;
 360
 361   // Holds set of ELF header flags for the target.
 362   uint32_t eflags = 0;
 363
 364   // The ELF spec defines two types of relocation table entries, RELA and
 365   // REL. RELA is a triplet of (offset, info, addend) while REL is a
 366   // tuple of (offset, info). Addends for REL are implicit and read from
 367   // the location where the relocations are applied. So, REL is more
 368   // compact than RELA but requires a bit of more work to process.
 369   //
 370   // (From the linker writer's view, this distinction is not necessary.
 371   // If the ELF had chosen whichever and sticked with it, it would have
 372   // been easier to write code to process relocations, but it's too late
 373   // to change the spec.)
 374   //
 375   // Each ABI defines its relocation type. IsRela is true if target
 376   // uses RELA. As far as we know, all 64-bit ABIs are using RELA. A
 377   // few 32-bit ABIs are using RELA too.
 378   bool isRela;
 379
 380   // True if we are creating position-independent code.
 381   bool isPic;
 382
 383   // 4 for ELF32, 8 for ELF64.
 384   int wordsize;
 385
 386   // Mode of MTE to write to the ELF note. Should be one of NT_MEMTAG_ASYNC (for
 387   // async), NT_MEMTAG_SYNC (for sync), or NT_MEMTAG_LEVEL_NONE (for none). If
 388   // async or sync is enabled, write the ELF note specifying the default MTE
 389   // mode.
 390   int androidMemtagMode;
 391   // Signal to the dynamic loader to enable heap MTE.
 392   bool androidMemtagHeap;
 393   // Signal to the dynamic loader that this binary expects stack MTE. Generally,
 394   // this means to map the primary and thread stacks as PROT_MTE. Note: This is
 395   // not supported on Android 11 & 12.
 396   bool androidMemtagStack;
 397
 398   unsigned threadCount;
 399 };
 400 struct ConfigWrapper {
 401   Config c;
 402   Config *operator->() { return &c; }
 403 };
 404
 405 LLVM_LIBRARY_VISIBILITY extern ConfigWrapper config;
 406
 407 struct DuplicateSymbol {
 408   const Symbol *sym;
 409   const InputFile *file;
 410   InputSectionBase *section;
 411   uint64_t value;
 412 };
 413
 414 struct Ctx {
 415   LinkerDriver driver;
 416   SmallVector<std::unique_ptr<MemoryBuffer>> memoryBuffers;
 417   SmallVector<ELFFileBase *, 0> objectFiles;
 418   SmallVector<SharedFile *, 0> sharedFiles;
 419   SmallVector<BinaryFile *, 0> binaryFiles;
 420   SmallVector<BitcodeFile *, 0> bitcodeFiles;
 421   SmallVector<BitcodeFile *, 0> lazyBitcodeFiles;
 422   SmallVector<InputSectionBase *, 0> inputSections;
 423   SmallVector<EhInputSection *, 0> ehInputSections;
 424   // Duplicate symbol candidates.
 425   SmallVector<DuplicateSymbol, 0> duplicates;
 426   // Symbols in a non-prevailing COMDAT group which should be changed to an
 427   // Undefined.
 428   SmallVector<std::pair<Symbol *, unsigned>, 0> nonPrevailingSyms;
 429   // A tuple of (reference, extractedFile, sym). Used by --why-extract=.
 430   SmallVector<std::tuple<std::string, const InputFile *, const Symbol &>, 0>
 431       whyExtractRecords;
 432   // A mapping from a symbol to an InputFile referencing it backward. Used by
 433   // --warn-backrefs.
 434   llvm::DenseMap<const Symbol *,
 435                  std::pair<const InputFile *, const InputFile *>>
 436       backwardReferences;
 437   // True if SHT_LLVM_SYMPART is used.
 438   std::atomic<bool> hasSympart{false};
 439   // True if there are TLS IE relocations. Set DF_STATIC_TLS if -shared.
 440   std::atomic<bool> hasTlsIe{false};
 441   // True if we need to reserve two .got entries for local-dynamic TLS model.
 442   std::atomic<bool> needsTlsLd{false};
 443
 444   void reset();
 445 };
 446
 447 LLVM_LIBRARY_VISIBILITY extern Ctx ctx;
 448
 449 // The first two elements of versionDefinitions represent VER_NDX_LOCAL and
 450 // VER_NDX_GLOBAL. This helper returns other elements.
 451 static inline ArrayRef<VersionDefinition> namedVersionDefs() {
 452   return llvm::ArrayRef(config->versionDefinitions).slice(2);
 453 }
 454
 455 void errorOrWarn(const Twine &msg);
 456
 457 static inline void internalLinkerError(StringRef loc, const Twine &msg) {
 458   errorOrWarn(loc + "internal linker error: " + msg + "\n" +
 459               llvm::getBugReportMsg());
 460 }
 461
 462 } // namespace lld::elf
 463
 464 #endif