1//===-- RuntimeDyldELF.h - Run-time dynamic linker for MC-JIT ---*- 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// ELF support for MC-JIT runtime dynamic linker.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_RUNTIMEDYLDELF_H
14#define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_RUNTIMEDYLDELF_H
15
16#include "RuntimeDyldImpl.h"
17#include "llvm/ADT/DenseMap.h"
18
19using namespace llvm;
20
21namespace llvm {
22namespace object {
23class ELFObjectFileBase;
24}
25
26class RuntimeDyldELF : public RuntimeDyldImpl {
27
28  void resolveRelocation(const SectionEntry &Section, uint64_t Offset,
29                         uint64_t Value, uint32_t Type, int64_t Addend,
30                         uint64_t SymOffset = 0, SID SectionID = 0);
31
32  void resolveX86_64Relocation(const SectionEntry &Section, uint64_t Offset,
33                               uint64_t Value, uint32_t Type, int64_t Addend,
34                               uint64_t SymOffset);
35
36  void resolveX86Relocation(const SectionEntry &Section, uint64_t Offset,
37                            uint32_t Value, uint32_t Type, int32_t Addend);
38
39  void resolveAArch64Relocation(const SectionEntry &Section, uint64_t Offset,
40                                uint64_t Value, uint32_t Type, int64_t Addend);
41
42  bool resolveAArch64ShortBranch(unsigned SectionID, relocation_iterator RelI,
43                                 const RelocationValueRef &Value);
44
45  void resolveAArch64Branch(unsigned SectionID, const RelocationValueRef &Value,
46                            relocation_iterator RelI, StubMap &Stubs);
47
48  void resolveARMRelocation(const SectionEntry &Section, uint64_t Offset,
49                            uint32_t Value, uint32_t Type, int32_t Addend);
50
51  void resolvePPC32Relocation(const SectionEntry &Section, uint64_t Offset,
52                              uint64_t Value, uint32_t Type, int64_t Addend);
53
54  void resolvePPC64Relocation(const SectionEntry &Section, uint64_t Offset,
55                              uint64_t Value, uint32_t Type, int64_t Addend);
56
57  void resolveSystemZRelocation(const SectionEntry &Section, uint64_t Offset,
58                                uint64_t Value, uint32_t Type, int64_t Addend);
59
60  void resolveBPFRelocation(const SectionEntry &Section, uint64_t Offset,
61                            uint64_t Value, uint32_t Type, int64_t Addend);
62
63  unsigned getMaxStubSize() const override {
64    if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be)
65      return 20; // movz; movk; movk; movk; br
66    if (Arch == Triple::arm || Arch == Triple::thumb)
67      return 8; // 32-bit instruction and 32-bit address
68    else if (IsMipsO32ABI || IsMipsN32ABI)
69      return 16;
70    else if (IsMipsN64ABI)
71      return 32;
72    else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le)
73      return 44;
74    else if (Arch == Triple::x86_64)
75      return 6; // 2-byte jmp instruction + 32-bit relative address
76    else if (Arch == Triple::systemz)
77      return 16;
78    else
79      return 0;
80  }
81
82  Align getStubAlignment() override {
83    if (Arch == Triple::systemz)
84      return Align(8);
85    else
86      return Align(1);
87  }
88
89  void setMipsABI(const ObjectFile &Obj) override;
90
91  Error findPPC64TOCSection(const object::ELFObjectFileBase &Obj,
92                            ObjSectionToIDMap &LocalSections,
93                            RelocationValueRef &Rel);
94  Error findOPDEntrySection(const object::ELFObjectFileBase &Obj,
95                            ObjSectionToIDMap &LocalSections,
96                            RelocationValueRef &Rel);
97
98protected:
99  size_t getGOTEntrySize() override;
100
101private:
102  SectionEntry &getSection(unsigned SectionID) { return Sections[SectionID]; }
103
104  // Allocate no GOT entries for use in the given section.
105  uint64_t allocateGOTEntries(unsigned no);
106
107  // Find GOT entry corresponding to relocation or create new one.
108  uint64_t findOrAllocGOTEntry(const RelocationValueRef &Value,
109                               unsigned GOTRelType);
110
111  // Resolve the relative address of GOTOffset in Section ID and place
112  // it at the given Offset
113  void resolveGOTOffsetRelocation(unsigned SectionID, uint64_t Offset,
114                                  uint64_t GOTOffset, uint32_t Type);
115
116  // For a GOT entry referenced from SectionID, compute a relocation entry
117  // that will place the final resolved value in the GOT slot
118  RelocationEntry computeGOTOffsetRE(uint64_t GOTOffset, uint64_t SymbolOffset,
119                                     unsigned Type);
120
121  // Compute the address in memory where we can find the placeholder
122  void *computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const;
123
124  // Split out common case for creating the RelocationEntry for when the
125  // relocation requires no particular advanced processing.
126  void processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value);
127
128  // Return matching *LO16 relocation (Mips specific)
129  uint32_t getMatchingLoRelocation(uint32_t RelType,
130                                   bool IsLocal = false) const;
131
132  // The tentative ID for the GOT section
133  unsigned GOTSectionID;
134
135  // Records the current number of allocated slots in the GOT
136  // (This would be equivalent to GOTEntries.size() were it not for relocations
137  // that consume more than one slot)
138  unsigned CurrentGOTIndex;
139
140protected:
141  // A map from section to a GOT section that has entries for section's GOT
142  // relocations. (Mips64 specific)
143  DenseMap<SID, SID> SectionToGOTMap;
144
145private:
146  // A map to avoid duplicate got entries (Mips64 specific)
147  StringMap<uint64_t> GOTSymbolOffsets;
148
149  // *HI16 relocations will be added for resolving when we find matching
150  // *LO16 part. (Mips specific)
151  SmallVector<std::pair<RelocationValueRef, RelocationEntry>, 8> PendingRelocs;
152
153  // When a module is loaded we save the SectionID of the EH frame section
154  // in a table until we receive a request to register all unregistered
155  // EH frame sections with the memory manager.
156  SmallVector<SID, 2> UnregisteredEHFrameSections;
157
158  // Map between GOT relocation value and corresponding GOT offset
159  std::map<RelocationValueRef, uint64_t> GOTOffsetMap;
160
161  /// The ID of the current IFunc stub section
162  unsigned IFuncStubSectionID = 0;
163  /// The current offset into the IFunc stub section
164  uint64_t IFuncStubOffset = 0;
165
166  /// A IFunc stub and its original symbol
167  struct IFuncStub {
168    /// The offset of this stub in the IFunc stub section
169    uint64_t StubOffset;
170    /// The symbol table entry of the original symbol
171    SymbolTableEntry OriginalSymbol;
172  };
173
174  /// The IFunc stubs
175  SmallVector<IFuncStub, 2> IFuncStubs;
176
177  /// Create the code for the IFunc resolver at the given address. This code
178  /// works together with the stubs created in createIFuncStub() to call the
179  /// resolver function and then jump to the real function address.
180  /// It must not be larger than 64B.
181  void createIFuncResolver(uint8_t *Addr) const;
182  /// Create the code for an IFunc stub for the IFunc that is defined in
183  /// section IFuncSectionID at offset IFuncOffset. The IFunc resolver created
184  /// by createIFuncResolver() is defined in the section IFuncStubSectionID at
185  /// offset IFuncResolverOffset. The code should be written into the section
186  /// with the id IFuncStubSectionID at the offset IFuncStubOffset.
187  void createIFuncStub(unsigned IFuncStubSectionID,
188                       uint64_t IFuncResolverOffset, uint64_t IFuncStubOffset,
189                       unsigned IFuncSectionID, uint64_t IFuncOffset);
190  /// Return the maximum size of a stub created by createIFuncStub()
191  unsigned getMaxIFuncStubSize() const;
192
193  void processNewSymbol(const SymbolRef &ObjSymbol,
194                        SymbolTableEntry &Entry) override;
195  bool relocationNeedsGot(const RelocationRef &R) const override;
196  bool relocationNeedsStub(const RelocationRef &R) const override;
197
198  // Process a GOTTPOFF TLS relocation for x86-64
199  // NOLINTNEXTLINE(readability-identifier-naming)
200  void processX86_64GOTTPOFFRelocation(unsigned SectionID, uint64_t Offset,
201                                       RelocationValueRef Value,
202                                       int64_t Addend);
203  // Process a TLSLD/TLSGD relocation for x86-64
204  // NOLINTNEXTLINE(readability-identifier-naming)
205  void processX86_64TLSRelocation(unsigned SectionID, uint64_t Offset,
206                                  uint64_t RelType, RelocationValueRef Value,
207                                  int64_t Addend,
208                                  const RelocationRef &GetAddrRelocation);
209
210public:
211  RuntimeDyldELF(RuntimeDyld::MemoryManager &MemMgr,
212                 JITSymbolResolver &Resolver);
213  ~RuntimeDyldELF() override;
214
215  static std::unique_ptr<RuntimeDyldELF>
216  create(Triple::ArchType Arch, RuntimeDyld::MemoryManager &MemMgr,
217         JITSymbolResolver &Resolver);
218
219  std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
220  loadObject(const object::ObjectFile &O) override;
221
222  void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override;
223  Expected<relocation_iterator>
224  processRelocationRef(unsigned SectionID, relocation_iterator RelI,
225                       const ObjectFile &Obj,
226                       ObjSectionToIDMap &ObjSectionToID,
227                       StubMap &Stubs) override;
228  bool isCompatibleFile(const object::ObjectFile &Obj) const override;
229  void registerEHFrames() override;
230  Error finalizeLoad(const ObjectFile &Obj,
231                     ObjSectionToIDMap &SectionMap) override;
232};
233
234} // end namespace llvm
235
236#endif
237