xref: /freebsd/contrib/llvm-project/lld/ELF/Config.h (revision aa1a8ff2) 
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   // InputFile for linker created symbols with no source location.
477   InputFile *internalFile;
478   // True if SHT_LLVM_SYMPART is used.
479   std::atomic<bool> hasSympart{false};
480   // True if there are TLS IE relocations. Set DF_STATIC_TLS if -shared.
481   std::atomic<bool> hasTlsIe{false};
482   // True if we need to reserve two .got entries for local-dynamic TLS model.
483   std::atomic<bool> needsTlsLd{false};
484   // True if all native vtable symbols have corresponding type info symbols
485   // during LTO.
486   bool ltoAllVtablesHaveTypeInfos;
487 
488   // Each symbol assignment and DEFINED(sym) reference is assigned an increasing
489   // order. Each DEFINED(sym) evaluation checks whether the reference happens
490   // before a possible `sym = expr;`.
491   unsigned scriptSymOrderCounter = 1;
492   llvm::DenseMap<const Symbol *, unsigned> scriptSymOrder;
493 
494   void reset();
495 
496   llvm::raw_fd_ostream openAuxiliaryFile(llvm::StringRef, std::error_code &);
497 };
498 
499 LLVM_LIBRARY_VISIBILITY extern Ctx ctx;
500 
501 // The first two elements of versionDefinitions represent VER_NDX_LOCAL and
502 // VER_NDX_GLOBAL. This helper returns other elements.
503 static inline ArrayRef<VersionDefinition> namedVersionDefs() {
504   return llvm::ArrayRef(config->versionDefinitions).slice(2);
505 }
506 
507 void errorOrWarn(const Twine &msg);
508 
509 static inline void internalLinkerError(StringRef loc, const Twine &msg) {
510   errorOrWarn(loc + "internal linker error: " + msg + "\n" +
511               llvm::getBugReportMsg());
512 }
513 
514 } // namespace lld::elf
515 
516 #endif
517