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