xref: /freebsd/contrib/llvm-project/llvm/lib/ExecutionEngine/JITLink/JITLink.cpp (revision 1db9f3b21e39176dd5b67cf8ac378633b172463e) 
1 //===------------- JITLink.cpp - Core Run-time JIT linker APIs ------------===//
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 #include "llvm/ExecutionEngine/JITLink/JITLink.h"
10 
11 #include "llvm/ADT/StringExtras.h"
12 #include "llvm/BinaryFormat/Magic.h"
13 #include "llvm/ExecutionEngine/JITLink/COFF.h"
14 #include "llvm/ExecutionEngine/JITLink/ELF.h"
15 #include "llvm/ExecutionEngine/JITLink/MachO.h"
16 #include "llvm/ExecutionEngine/JITLink/aarch64.h"
17 #include "llvm/ExecutionEngine/JITLink/i386.h"
18 #include "llvm/ExecutionEngine/JITLink/loongarch.h"
19 #include "llvm/ExecutionEngine/JITLink/x86_64.h"
20 #include "llvm/Support/Format.h"
21 #include "llvm/Support/MemoryBuffer.h"
22 #include "llvm/Support/raw_ostream.h"
23 
24 using namespace llvm;
25 using namespace llvm::object;
26 
27 #define DEBUG_TYPE "jitlink"
28 
29 namespace {
30 
31 enum JITLinkErrorCode { GenericJITLinkError = 1 };
32 
33 // FIXME: This class is only here to support the transition to llvm::Error. It
34 // will be removed once this transition is complete. Clients should prefer to
35 // deal with the Error value directly, rather than converting to error_code.
36 class JITLinkerErrorCategory : public std::error_category {
37 public:
38   const char *name() const noexcept override { return "runtimedyld"; }
39 
40   std::string message(int Condition) const override {
41     switch (static_cast<JITLinkErrorCode>(Condition)) {
42     case GenericJITLinkError:
43       return "Generic JITLink error";
44     }
45     llvm_unreachable("Unrecognized JITLinkErrorCode");
46   }
47 };
48 
49 } // namespace
50 
51 namespace llvm {
52 namespace jitlink {
53 
54 char JITLinkError::ID = 0;
55 
56 void JITLinkError::log(raw_ostream &OS) const { OS << ErrMsg; }
57 
58 std::error_code JITLinkError::convertToErrorCode() const {
59   static JITLinkerErrorCategory TheJITLinkerErrorCategory;
60   return std::error_code(GenericJITLinkError, TheJITLinkerErrorCategory);
61 }
62 
63 const char *getGenericEdgeKindName(Edge::Kind K) {
64   switch (K) {
65   case Edge::Invalid:
66     return "INVALID RELOCATION";
67   case Edge::KeepAlive:
68     return "Keep-Alive";
69   default:
70     return "<Unrecognized edge kind>";
71   }
72 }
73 
74 const char *getLinkageName(Linkage L) {
75   switch (L) {
76   case Linkage::Strong:
77     return "strong";
78   case Linkage::Weak:
79     return "weak";
80   }
81   llvm_unreachable("Unrecognized llvm.jitlink.Linkage enum");
82 }
83 
84 const char *getScopeName(Scope S) {
85   switch (S) {
86   case Scope::Default:
87     return "default";
88   case Scope::Hidden:
89     return "hidden";
90   case Scope::Local:
91     return "local";
92   }
93   llvm_unreachable("Unrecognized llvm.jitlink.Scope enum");
94 }
95 
96 bool isCStringBlock(Block &B) {
97   if (B.getSize() == 0) // Empty blocks are not valid C-strings.
98     return false;
99 
100   // Zero-fill blocks of size one are valid empty strings.
101   if (B.isZeroFill())
102     return B.getSize() == 1;
103 
104   for (size_t I = 0; I != B.getSize() - 1; ++I)
105     if (B.getContent()[I] == '\0')
106       return false;
107 
108   return B.getContent()[B.getSize() - 1] == '\0';
109 }
110 
111 raw_ostream &operator<<(raw_ostream &OS, const Block &B) {
112   return OS << B.getAddress() << " -- " << (B.getAddress() + B.getSize())
113             << ": "
114             << "size = " << formatv("{0:x8}", B.getSize()) << ", "
115             << (B.isZeroFill() ? "zero-fill" : "content")
116             << ", align = " << B.getAlignment()
117             << ", align-ofs = " << B.getAlignmentOffset()
118             << ", section = " << B.getSection().getName();
119 }
120 
121 raw_ostream &operator<<(raw_ostream &OS, const Symbol &Sym) {
122   OS << Sym.getAddress() << " (" << (Sym.isDefined() ? "block" : "addressable")
123      << " + " << formatv("{0:x8}", Sym.getOffset())
124      << "): size: " << formatv("{0:x8}", Sym.getSize())
125      << ", linkage: " << formatv("{0:6}", getLinkageName(Sym.getLinkage()))
126      << ", scope: " << formatv("{0:8}", getScopeName(Sym.getScope())) << ", "
127      << (Sym.isLive() ? "live" : "dead") << "  -   "
128      << (Sym.hasName() ? Sym.getName() : "<anonymous symbol>");
129   return OS;
130 }
131 
132 void printEdge(raw_ostream &OS, const Block &B, const Edge &E,
133                StringRef EdgeKindName) {
134   OS << "edge@" << B.getAddress() + E.getOffset() << ": " << B.getAddress()
135      << " + " << formatv("{0:x}", E.getOffset()) << " -- " << EdgeKindName
136      << " -> ";
137 
138   auto &TargetSym = E.getTarget();
139   if (TargetSym.hasName())
140     OS << TargetSym.getName();
141   else {
142     auto &TargetBlock = TargetSym.getBlock();
143     auto &TargetSec = TargetBlock.getSection();
144     orc::ExecutorAddr SecAddress(~uint64_t(0));
145     for (auto *B : TargetSec.blocks())
146       if (B->getAddress() < SecAddress)
147         SecAddress = B->getAddress();
148 
149     orc::ExecutorAddrDiff SecDelta = TargetSym.getAddress() - SecAddress;
150     OS << TargetSym.getAddress() << " (section " << TargetSec.getName();
151     if (SecDelta)
152       OS << " + " << formatv("{0:x}", SecDelta);
153     OS << " / block " << TargetBlock.getAddress();
154     if (TargetSym.getOffset())
155       OS << " + " << formatv("{0:x}", TargetSym.getOffset());
156     OS << ")";
157   }
158 
159   if (E.getAddend() != 0)
160     OS << " + " << E.getAddend();
161 }
162 
163 Section::~Section() {
164   for (auto *Sym : Symbols)
165     Sym->~Symbol();
166   for (auto *B : Blocks)
167     B->~Block();
168 }
169 
170 Block &LinkGraph::splitBlock(Block &B, size_t SplitIndex,
171                              SplitBlockCache *Cache) {
172 
173   assert(SplitIndex > 0 && "splitBlock can not be called with SplitIndex == 0");
174 
175   // If the split point covers all of B then just return B.
176   if (SplitIndex == B.getSize())
177     return B;
178 
179   assert(SplitIndex < B.getSize() && "SplitIndex out of range");
180 
181   // Create the new block covering [ 0, SplitIndex ).
182   auto &NewBlock =
183       B.isZeroFill()
184           ? createZeroFillBlock(B.getSection(), SplitIndex, B.getAddress(),
185                                 B.getAlignment(), B.getAlignmentOffset())
186           : createContentBlock(
187                 B.getSection(), B.getContent().slice(0, SplitIndex),
188                 B.getAddress(), B.getAlignment(), B.getAlignmentOffset());
189 
190   // Modify B to cover [ SplitIndex, B.size() ).
191   B.setAddress(B.getAddress() + SplitIndex);
192   B.setContent(B.getContent().slice(SplitIndex));
193   B.setAlignmentOffset((B.getAlignmentOffset() + SplitIndex) %
194                        B.getAlignment());
195 
196   // Handle edge transfer/update.
197   {
198     // Copy edges to NewBlock (recording their iterators so that we can remove
199     // them from B), and update of Edges remaining on B.
200     std::vector<Block::edge_iterator> EdgesToRemove;
201     for (auto I = B.edges().begin(); I != B.edges().end();) {
202       if (I->getOffset() < SplitIndex) {
203         NewBlock.addEdge(*I);
204         I = B.removeEdge(I);
205       } else {
206         I->setOffset(I->getOffset() - SplitIndex);
207         ++I;
208       }
209     }
210   }
211 
212   // Handle symbol transfer/update.
213   {
214     // Initialize the symbols cache if necessary.
215     SplitBlockCache LocalBlockSymbolsCache;
216     if (!Cache)
217       Cache = &LocalBlockSymbolsCache;
218     if (*Cache == std::nullopt) {
219       *Cache = SplitBlockCache::value_type();
220       for (auto *Sym : B.getSection().symbols())
221         if (&Sym->getBlock() == &B)
222           (*Cache)->push_back(Sym);
223 
224       llvm::sort(**Cache, [](const Symbol *LHS, const Symbol *RHS) {
225         return LHS->getOffset() > RHS->getOffset();
226       });
227     }
228     auto &BlockSymbols = **Cache;
229 
230     // Transfer all symbols with offset less than SplitIndex to NewBlock.
231     while (!BlockSymbols.empty() &&
232            BlockSymbols.back()->getOffset() < SplitIndex) {
233       auto *Sym = BlockSymbols.back();
234       // If the symbol extends beyond the split, update the size to be within
235       // the new block.
236       if (Sym->getOffset() + Sym->getSize() > SplitIndex)
237         Sym->setSize(SplitIndex - Sym->getOffset());
238       Sym->setBlock(NewBlock);
239       BlockSymbols.pop_back();
240     }
241 
242     // Update offsets for all remaining symbols in B.
243     for (auto *Sym : BlockSymbols)
244       Sym->setOffset(Sym->getOffset() - SplitIndex);
245   }
246 
247   return NewBlock;
248 }
249 
250 void LinkGraph::dump(raw_ostream &OS) {
251   DenseMap<Block *, std::vector<Symbol *>> BlockSymbols;
252 
253   // Map from blocks to the symbols pointing at them.
254   for (auto *Sym : defined_symbols())
255     BlockSymbols[&Sym->getBlock()].push_back(Sym);
256 
257   // For each block, sort its symbols by something approximating
258   // relevance.
259   for (auto &KV : BlockSymbols)
260     llvm::sort(KV.second, [](const Symbol *LHS, const Symbol *RHS) {
261       if (LHS->getOffset() != RHS->getOffset())
262         return LHS->getOffset() < RHS->getOffset();
263       if (LHS->getLinkage() != RHS->getLinkage())
264         return LHS->getLinkage() < RHS->getLinkage();
265       if (LHS->getScope() != RHS->getScope())
266         return LHS->getScope() < RHS->getScope();
267       if (LHS->hasName()) {
268         if (!RHS->hasName())
269           return true;
270         return LHS->getName() < RHS->getName();
271       }
272       return false;
273     });
274 
275   for (auto &Sec : sections()) {
276     OS << "section " << Sec.getName() << ":\n\n";
277 
278     std::vector<Block *> SortedBlocks;
279     llvm::copy(Sec.blocks(), std::back_inserter(SortedBlocks));
280     llvm::sort(SortedBlocks, [](const Block *LHS, const Block *RHS) {
281       return LHS->getAddress() < RHS->getAddress();
282     });
283 
284     for (auto *B : SortedBlocks) {
285       OS << "  block " << B->getAddress()
286          << " size = " << formatv("{0:x8}", B->getSize())
287          << ", align = " << B->getAlignment()
288          << ", alignment-offset = " << B->getAlignmentOffset();
289       if (B->isZeroFill())
290         OS << ", zero-fill";
291       OS << "\n";
292 
293       auto BlockSymsI = BlockSymbols.find(B);
294       if (BlockSymsI != BlockSymbols.end()) {
295         OS << "    symbols:\n";
296         auto &Syms = BlockSymsI->second;
297         for (auto *Sym : Syms)
298           OS << "      " << *Sym << "\n";
299       } else
300         OS << "    no symbols\n";
301 
302       if (!B->edges_empty()) {
303         OS << "    edges:\n";
304         std::vector<Edge> SortedEdges;
305         llvm::copy(B->edges(), std::back_inserter(SortedEdges));
306         llvm::sort(SortedEdges, [](const Edge &LHS, const Edge &RHS) {
307           return LHS.getOffset() < RHS.getOffset();
308         });
309         for (auto &E : SortedEdges) {
310           OS << "      " << B->getFixupAddress(E) << " (block + "
311              << formatv("{0:x8}", E.getOffset()) << "), addend = ";
312           if (E.getAddend() >= 0)
313             OS << formatv("+{0:x8}", E.getAddend());
314           else
315             OS << formatv("-{0:x8}", -E.getAddend());
316           OS << ", kind = " << getEdgeKindName(E.getKind()) << ", target = ";
317           if (E.getTarget().hasName())
318             OS << E.getTarget().getName();
319           else
320             OS << "addressable@"
321                << formatv("{0:x16}", E.getTarget().getAddress()) << "+"
322                << formatv("{0:x8}", E.getTarget().getOffset());
323           OS << "\n";
324         }
325       } else
326         OS << "    no edges\n";
327       OS << "\n";
328     }
329   }
330 
331   OS << "Absolute symbols:\n";
332   if (!absolute_symbols().empty()) {
333     for (auto *Sym : absolute_symbols())
334       OS << "  " << Sym->getAddress() << ": " << *Sym << "\n";
335   } else
336     OS << "  none\n";
337 
338   OS << "\nExternal symbols:\n";
339   if (!external_symbols().empty()) {
340     for (auto *Sym : external_symbols())
341       OS << "  " << Sym->getAddress() << ": " << *Sym << "\n";
342   } else
343     OS << "  none\n";
344 }
345 
346 raw_ostream &operator<<(raw_ostream &OS, const SymbolLookupFlags &LF) {
347   switch (LF) {
348   case SymbolLookupFlags::RequiredSymbol:
349     return OS << "RequiredSymbol";
350   case SymbolLookupFlags::WeaklyReferencedSymbol:
351     return OS << "WeaklyReferencedSymbol";
352   }
353   llvm_unreachable("Unrecognized lookup flags");
354 }
355 
356 void JITLinkAsyncLookupContinuation::anchor() {}
357 
358 JITLinkContext::~JITLinkContext() = default;
359 
360 bool JITLinkContext::shouldAddDefaultTargetPasses(const Triple &TT) const {
361   return true;
362 }
363 
364 LinkGraphPassFunction JITLinkContext::getMarkLivePass(const Triple &TT) const {
365   return LinkGraphPassFunction();
366 }
367 
368 Error JITLinkContext::modifyPassConfig(LinkGraph &G,
369                                        PassConfiguration &Config) {
370   return Error::success();
371 }
372 
373 Error markAllSymbolsLive(LinkGraph &G) {
374   for (auto *Sym : G.defined_symbols())
375     Sym->setLive(true);
376   return Error::success();
377 }
378 
379 Error makeTargetOutOfRangeError(const LinkGraph &G, const Block &B,
380                                 const Edge &E) {
381   std::string ErrMsg;
382   {
383     raw_string_ostream ErrStream(ErrMsg);
384     Section &Sec = B.getSection();
385     ErrStream << "In graph " << G.getName() << ", section " << Sec.getName()
386               << ": relocation target ";
387     if (E.getTarget().hasName()) {
388       ErrStream << "\"" << E.getTarget().getName() << "\"";
389     } else
390       ErrStream << E.getTarget().getBlock().getSection().getName() << " + "
391                 << formatv("{0:x}", E.getOffset());
392     ErrStream << " at address " << formatv("{0:x}", E.getTarget().getAddress())
393               << " is out of range of " << G.getEdgeKindName(E.getKind())
394               << " fixup at " << formatv("{0:x}", B.getFixupAddress(E)) << " (";
395 
396     Symbol *BestSymbolForBlock = nullptr;
397     for (auto *Sym : Sec.symbols())
398       if (&Sym->getBlock() == &B && Sym->hasName() && Sym->getOffset() == 0 &&
399           (!BestSymbolForBlock ||
400            Sym->getScope() < BestSymbolForBlock->getScope() ||
401            Sym->getLinkage() < BestSymbolForBlock->getLinkage()))
402         BestSymbolForBlock = Sym;
403 
404     if (BestSymbolForBlock)
405       ErrStream << BestSymbolForBlock->getName() << ", ";
406     else
407       ErrStream << "<anonymous block> @ ";
408 
409     ErrStream << formatv("{0:x}", B.getAddress()) << " + "
410               << formatv("{0:x}", E.getOffset()) << ")";
411   }
412   return make_error<JITLinkError>(std::move(ErrMsg));
413 }
414 
415 Error makeAlignmentError(llvm::orc::ExecutorAddr Loc, uint64_t Value, int N,
416                          const Edge &E) {
417   return make_error<JITLinkError>("0x" + llvm::utohexstr(Loc.getValue()) +
418                                   " improper alignment for relocation " +
419                                   formatv("{0:d}", E.getKind()) + ": 0x" +
420                                   llvm::utohexstr(Value) +
421                                   " is not aligned to " + Twine(N) + " bytes");
422 }
423 
424 AnonymousPointerCreator getAnonymousPointerCreator(const Triple &TT) {
425   switch (TT.getArch()) {
426   case Triple::aarch64:
427     return aarch64::createAnonymousPointer;
428   case Triple::x86_64:
429     return x86_64::createAnonymousPointer;
430   case Triple::x86:
431     return i386::createAnonymousPointer;
432   case Triple::loongarch32:
433   case Triple::loongarch64:
434     return loongarch::createAnonymousPointer;
435   default:
436     return nullptr;
437   }
438 }
439 
440 PointerJumpStubCreator getPointerJumpStubCreator(const Triple &TT) {
441   switch (TT.getArch()) {
442   case Triple::aarch64:
443     return aarch64::createAnonymousPointerJumpStub;
444   case Triple::x86_64:
445     return x86_64::createAnonymousPointerJumpStub;
446   case Triple::x86:
447     return i386::createAnonymousPointerJumpStub;
448   case Triple::loongarch32:
449   case Triple::loongarch64:
450     return loongarch::createAnonymousPointerJumpStub;
451   default:
452     return nullptr;
453   }
454 }
455 
456 Expected<std::unique_ptr<LinkGraph>>
457 createLinkGraphFromObject(MemoryBufferRef ObjectBuffer) {
458   auto Magic = identify_magic(ObjectBuffer.getBuffer());
459   switch (Magic) {
460   case file_magic::macho_object:
461     return createLinkGraphFromMachOObject(ObjectBuffer);
462   case file_magic::elf_relocatable:
463     return createLinkGraphFromELFObject(ObjectBuffer);
464   case file_magic::coff_object:
465     return createLinkGraphFromCOFFObject(ObjectBuffer);
466   default:
467     return make_error<JITLinkError>("Unsupported file format");
468   };
469 }
470 
471 std::unique_ptr<LinkGraph> absoluteSymbolsLinkGraph(const Triple &TT,
472                                                     orc::SymbolMap Symbols) {
473   unsigned PointerSize;
474   endianness Endianness =
475       TT.isLittleEndian() ? endianness::little : endianness::big;
476   switch (TT.getArch()) {
477   case Triple::aarch64:
478   case llvm::Triple::riscv64:
479   case Triple::x86_64:
480     PointerSize = 8;
481     break;
482   case llvm::Triple::arm:
483   case llvm::Triple::riscv32:
484   case llvm::Triple::x86:
485     PointerSize = 4;
486     break;
487   default:
488     llvm::report_fatal_error("unhandled target architecture");
489   }
490 
491   static std::atomic<uint64_t> Counter = {0};
492   auto Index = Counter.fetch_add(1, std::memory_order_relaxed);
493   auto G = std::make_unique<LinkGraph>(
494       "<Absolute Symbols " + std::to_string(Index) + ">", TT, PointerSize,
495       Endianness, /*GetEdgeKindName=*/nullptr);
496   for (auto &[Name, Def] : Symbols) {
497     auto &Sym =
498         G->addAbsoluteSymbol(*Name, Def.getAddress(), /*Size=*/0,
499                              Linkage::Strong, Scope::Default, /*IsLive=*/true);
500     Sym.setCallable(Def.getFlags().isCallable());
501   }
502 
503   return G;
504 }
505 
506 void link(std::unique_ptr<LinkGraph> G, std::unique_ptr<JITLinkContext> Ctx) {
507   switch (G->getTargetTriple().getObjectFormat()) {
508   case Triple::MachO:
509     return link_MachO(std::move(G), std::move(Ctx));
510   case Triple::ELF:
511     return link_ELF(std::move(G), std::move(Ctx));
512   case Triple::COFF:
513     return link_COFF(std::move(G), std::move(Ctx));
514   default:
515     Ctx->notifyFailed(make_error<JITLinkError>("Unsupported object format"));
516   };
517 }
518 
519 } // end namespace jitlink
520 } // end namespace llvm
521