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

source code of llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldMachOI386.h