1//===---- RuntimeDyldMachOI386.h ---- MachO/I386 specific code. ---*- 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 LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDMACHOI386_H
10#define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDMACHOI386_H
11
12#include "../RuntimeDyldMachO.h"
13#include <string>
14
15#define DEBUG_TYPE "dyld"
16
17namespace llvm {
18
19class RuntimeDyldMachOI386
20 : public RuntimeDyldMachOCRTPBase<RuntimeDyldMachOI386> {
21public:
22
23 typedef uint32_t TargetPtrT;
24
25 RuntimeDyldMachOI386(RuntimeDyld::MemoryManager &MM,
26 JITSymbolResolver &Resolver)
27 : RuntimeDyldMachOCRTPBase(MM, Resolver) {}
28
29 unsigned getMaxStubSize() const override { return 0; }
30
31 unsigned getStubAlignment() override { return 1; }
32
33 Expected<relocation_iterator>
34 processRelocationRef(unsigned SectionID, relocation_iterator RelI,
35 const ObjectFile &BaseObjT,
36 ObjSectionToIDMap &ObjSectionToID,
37 StubMap &Stubs) override {
38 const MachOObjectFile &Obj =
39 static_cast<const MachOObjectFile &>(BaseObjT);
40 MachO::any_relocation_info RelInfo =
41 Obj.getRelocation(RelI->getRawDataRefImpl());
42 uint32_t RelType = Obj.getAnyRelocationType(RelInfo);
43
44 if (Obj.isRelocationScattered(RelInfo)) {
45 if (RelType == MachO::GENERIC_RELOC_SECTDIFF ||
46 RelType == MachO::GENERIC_RELOC_LOCAL_SECTDIFF)
47 return processSECTDIFFRelocation(SectionID, RelI, Obj,
48 ObjSectionToID);
49 else if (RelType == MachO::GENERIC_RELOC_VANILLA)
50 return processScatteredVANILLA(SectionID, RelI, Obj, ObjSectionToID);
51 return make_error<RuntimeDyldError>(("Unhandled I386 scattered relocation "
52 "type: " + Twine(RelType)).str());
53 }
54
55 switch (RelType) {
56 UNIMPLEMENTED_RELOC(MachO::GENERIC_RELOC_PAIR);
57 UNIMPLEMENTED_RELOC(MachO::GENERIC_RELOC_PB_LA_PTR);
58 UNIMPLEMENTED_RELOC(MachO::GENERIC_RELOC_TLV);
59 default:
60 if (RelType > MachO::GENERIC_RELOC_TLV)
61 return make_error<RuntimeDyldError>(("MachO I386 relocation type " +
62 Twine(RelType) +
63 " is out of range").str());
64 break;
65 }
66
67 RelocationEntry RE(getRelocationEntry(SectionID, Obj, RelI));
68 RE.Addend = memcpyAddend(RE);
69 RelocationValueRef Value;
70 if (auto ValueOrErr = getRelocationValueRef(Obj, RelI, RE, ObjSectionToID))
71 Value = *ValueOrErr;
72 else
73 return ValueOrErr.takeError();
74
75 // Addends for external, PC-rel relocations on i386 point back to the zero
76 // offset. Calculate the final offset from the relocation target instead.
77 // This allows us to use the same logic for both external and internal
78 // relocations in resolveI386RelocationRef.
79 // bool IsExtern = Obj.getPlainRelocationExternal(RelInfo);
80 // if (IsExtern && RE.IsPCRel) {
81 // uint64_t RelocAddr = 0;
82 // RelI->getAddress(RelocAddr);
83 // Value.Addend += RelocAddr + 4;
84 // }
85 if (RE.IsPCRel)
86 makeValueAddendPCRel(Value, RelI, 1 << RE.Size);
87
88 RE.Addend = Value.Offset;
89
90 if (Value.SymbolName)
91 addRelocationForSymbol(RE, Value.SymbolName);
92 else
93 addRelocationForSection(RE, Value.SectionID);
94
95 return ++RelI;
96 }
97
98 void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override {
99 LLVM_DEBUG(dumpRelocationToResolve(RE, Value));
100
101 const SectionEntry &Section = Sections[RE.SectionID];
102 uint8_t *LocalAddress = Section.getAddressWithOffset(RE.Offset);
103
104 if (RE.IsPCRel) {
105 uint64_t FinalAddress = Section.getLoadAddressWithOffset(RE.Offset);
106 Value -= FinalAddress + 4; // see MachOX86_64::resolveRelocation.
107 }
108
109 switch (RE.RelType) {
110 case MachO::GENERIC_RELOC_VANILLA:
111 writeBytesUnaligned(Value + RE.Addend, LocalAddress, 1 << RE.Size);
112 break;
113 case MachO::GENERIC_RELOC_SECTDIFF:
114 case MachO::GENERIC_RELOC_LOCAL_SECTDIFF: {
115 uint64_t SectionABase = Sections[RE.Sections.SectionA].getLoadAddress();
116 uint64_t SectionBBase = Sections[RE.Sections.SectionB].getLoadAddress();
117 assert((Value == SectionABase || Value == SectionBBase) &&
118 "Unexpected SECTDIFF relocation value.");
119 Value = SectionABase - SectionBBase + RE.Addend;
120 writeBytesUnaligned(Value, LocalAddress, 1 << RE.Size);
121 break;
122 }
123 default:
124 llvm_unreachable("Invalid relocation type!");
125 }
126 }
127
128 Error finalizeSection(const ObjectFile &Obj, unsigned SectionID,
129 const SectionRef &Section) {
130 StringRef Name;
131 if (Expected<StringRef> NameOrErr = Section.getName())
132 Name = *NameOrErr;
133 else
134 consumeError(NameOrErr.takeError());
135
136 if (Name == "__jump_table")
137 return populateJumpTable(cast<MachOObjectFile>(Obj), Section, SectionID);
138 else if (Name == "__pointers")
139 return populateIndirectSymbolPointersSection(cast<MachOObjectFile>(Obj),
140 Section, SectionID);
141 return Error::success();
142 }
143
144private:
145 Expected<relocation_iterator>
146 processSECTDIFFRelocation(unsigned SectionID, relocation_iterator RelI,
147 const ObjectFile &BaseObjT,
148 ObjSectionToIDMap &ObjSectionToID) {
149 const MachOObjectFile &Obj =
150 static_cast<const MachOObjectFile&>(BaseObjT);
151 MachO::any_relocation_info RE =
152 Obj.getRelocation(RelI->getRawDataRefImpl());
153
154 SectionEntry &Section = Sections[SectionID];
155 uint32_t RelocType = Obj.getAnyRelocationType(RE);
156 bool IsPCRel = Obj.getAnyRelocationPCRel(RE);
157 unsigned Size = Obj.getAnyRelocationLength(RE);
158 uint64_t Offset = RelI->getOffset();
159 uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
160 unsigned NumBytes = 1 << Size;
161 uint64_t Addend = readBytesUnaligned(LocalAddress, NumBytes);
162
163 ++RelI;
164 MachO::any_relocation_info RE2 =
165 Obj.getRelocation(RelI->getRawDataRefImpl());
166
167 uint32_t AddrA = Obj.getScatteredRelocationValue(RE);
168 section_iterator SAI = getSectionByAddress(Obj, AddrA);
169 assert(SAI != Obj.section_end() && "Can't find section for address A");
170 uint64_t SectionABase = SAI->getAddress();
171 uint64_t SectionAOffset = AddrA - SectionABase;
172 SectionRef SectionA = *SAI;
173 bool IsCode = SectionA.isText();
174 uint32_t SectionAID = ~0U;
175 if (auto SectionAIDOrErr =
176 findOrEmitSection(Obj, SectionA, IsCode, ObjSectionToID))
177 SectionAID = *SectionAIDOrErr;
178 else
179 return SectionAIDOrErr.takeError();
180
181 uint32_t AddrB = Obj.getScatteredRelocationValue(RE2);
182 section_iterator SBI = getSectionByAddress(Obj, AddrB);
183 assert(SBI != Obj.section_end() && "Can't find section for address B");
184 uint64_t SectionBBase = SBI->getAddress();
185 uint64_t SectionBOffset = AddrB - SectionBBase;
186 SectionRef SectionB = *SBI;
187 uint32_t SectionBID = ~0U;
188 if (auto SectionBIDOrErr =
189 findOrEmitSection(Obj, SectionB, IsCode, ObjSectionToID))
190 SectionBID = *SectionBIDOrErr;
191 else
192 return SectionBIDOrErr.takeError();
193
194 // Compute the addend 'C' from the original expression 'A - B + C'.
195 Addend -= AddrA - AddrB;
196
197 LLVM_DEBUG(dbgs() << "Found SECTDIFF: AddrA: " << AddrA
198 << ", AddrB: " << AddrB << ", Addend: " << Addend
199 << ", SectionA ID: " << SectionAID << ", SectionAOffset: "
200 << SectionAOffset << ", SectionB ID: " << SectionBID
201 << ", SectionBOffset: " << SectionBOffset << "\n");
202 RelocationEntry R(SectionID, Offset, RelocType, Addend, SectionAID,
203 SectionAOffset, SectionBID, SectionBOffset,
204 IsPCRel, Size);
205
206 addRelocationForSection(R, SectionAID);
207
208 return ++RelI;
209 }
210
211 // Populate stubs in __jump_table section.
212 Error populateJumpTable(const MachOObjectFile &Obj,
213 const SectionRef &JTSection,
214 unsigned JTSectionID) {
215 MachO::dysymtab_command DySymTabCmd = Obj.getDysymtabLoadCommand();
216 MachO::section Sec32 = Obj.getSection(JTSection.getRawDataRefImpl());
217 uint32_t JTSectionSize = Sec32.size;
218 unsigned FirstIndirectSymbol = Sec32.reserved1;
219 unsigned JTEntrySize = Sec32.reserved2;
220 unsigned NumJTEntries = JTSectionSize / JTEntrySize;
221 uint8_t *JTSectionAddr = getSectionAddress(JTSectionID);
222 unsigned JTEntryOffset = 0;
223
224 if (JTSectionSize % JTEntrySize != 0)
225 return make_error<RuntimeDyldError>("Jump-table section does not contain "
226 "a whole number of stubs?");
227
228 for (unsigned i = 0; i < NumJTEntries; ++i) {
229 unsigned SymbolIndex =
230 Obj.getIndirectSymbolTableEntry(DySymTabCmd, FirstIndirectSymbol + i);
231 symbol_iterator SI = Obj.getSymbolByIndex(SymbolIndex);
232 Expected<StringRef> IndirectSymbolName = SI->getName();
233 if (!IndirectSymbolName)
234 return IndirectSymbolName.takeError();
235 uint8_t *JTEntryAddr = JTSectionAddr + JTEntryOffset;
236 createStubFunction(JTEntryAddr);
237 RelocationEntry RE(JTSectionID, JTEntryOffset + 1,
238 MachO::GENERIC_RELOC_VANILLA, 0, true, 2);
239 addRelocationForSymbol(RE, *IndirectSymbolName);
240 JTEntryOffset += JTEntrySize;
241 }
242
243 return Error::success();
244 }
245
246};
247}
248
249#undef DEBUG_TYPE
250
251#endif
252