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