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1 : //===--- RuntimeDyldCOFFI386.h --- COFF/X86_64 specific code ---*- C++ --*-===//
2 : //
3 : // The LLVM Compiler Infrastructure
4 : //
5 : // This file is distributed under the University of Illinois Open Source
6 : // License. See LICENSE.TXT for details.
7 : //
8 : //===----------------------------------------------------------------------===//
9 : //
10 : // COFF x86 support for MC-JIT runtime dynamic linker.
11 : //
12 : //===----------------------------------------------------------------------===//
13 :
14 : #ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFFI386_H
15 : #define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFFI386_H
16 :
17 : #include "../RuntimeDyldCOFF.h"
18 : #include "llvm/BinaryFormat/COFF.h"
19 : #include "llvm/Object/COFF.h"
20 :
21 : #define DEBUG_TYPE "dyld"
22 :
23 : namespace llvm {
24 :
25 : class RuntimeDyldCOFFI386 : public RuntimeDyldCOFF {
26 : public:
27 : RuntimeDyldCOFFI386(RuntimeDyld::MemoryManager &MM,
28 : JITSymbolResolver &Resolver)
29 1 : : RuntimeDyldCOFF(MM, Resolver) {}
30 :
31 3 : unsigned getMaxStubSize() override {
32 3 : return 8; // 2-byte jmp instruction + 32-bit relative address + 2 byte pad
33 : }
34 :
35 5 : unsigned getStubAlignment() override { return 1; }
36 :
37 : Expected<relocation_iterator>
38 14 : processRelocationRef(unsigned SectionID,
39 : relocation_iterator RelI,
40 : const ObjectFile &Obj,
41 : ObjSectionToIDMap &ObjSectionToID,
42 : StubMap &Stubs) override {
43 :
44 14 : auto Symbol = RelI->getSymbol();
45 14 : if (Symbol == Obj.symbol_end())
46 0 : report_fatal_error("Unknown symbol in relocation");
47 :
48 : Expected<StringRef> TargetNameOrErr = Symbol->getName();
49 14 : if (!TargetNameOrErr)
50 : return TargetNameOrErr.takeError();
51 14 : StringRef TargetName = *TargetNameOrErr;
52 :
53 : auto SectionOrErr = Symbol->getSection();
54 14 : if (!SectionOrErr)
55 : return SectionOrErr.takeError();
56 14 : auto Section = *SectionOrErr;
57 :
58 14 : uint64_t RelType = RelI->getType();
59 14 : uint64_t Offset = RelI->getOffset();
60 :
61 : // Determine the Addend used to adjust the relocation value.
62 : uint64_t Addend = 0;
63 14 : SectionEntry &AddendSection = Sections[SectionID];
64 14 : uintptr_t ObjTarget = AddendSection.getObjAddress() + Offset;
65 14 : uint8_t *Displacement = (uint8_t *)ObjTarget;
66 :
67 : switch (RelType) {
68 13 : case COFF::IMAGE_REL_I386_DIR32:
69 : case COFF::IMAGE_REL_I386_DIR32NB:
70 : case COFF::IMAGE_REL_I386_SECREL:
71 : case COFF::IMAGE_REL_I386_REL32: {
72 13 : Addend = readBytesUnaligned(Displacement, 4);
73 13 : break;
74 : }
75 : default:
76 : break;
77 : }
78 :
79 : #if !defined(NDEBUG)
80 : SmallString<32> RelTypeName;
81 : RelI->getTypeName(RelTypeName);
82 : #endif
83 : LLVM_DEBUG(dbgs() << "\t\tIn Section " << SectionID << " Offset " << Offset
84 : << " RelType: " << RelTypeName << " TargetName: "
85 : << TargetName << " Addend " << Addend << "\n");
86 :
87 : unsigned TargetSectionID = -1;
88 14 : if (Section == Obj.section_end()) {
89 3 : RelocationEntry RE(SectionID, Offset, RelType, 0, -1, 0, 0, 0, false, 0);
90 3 : addRelocationForSymbol(RE, TargetName);
91 : } else {
92 11 : if (auto TargetSectionIDOrErr =
93 11 : findOrEmitSection(Obj, *Section, Section->isText(), ObjSectionToID))
94 11 : TargetSectionID = *TargetSectionIDOrErr;
95 : else
96 : return TargetSectionIDOrErr.takeError();
97 :
98 11 : switch (RelType) {
99 : case COFF::IMAGE_REL_I386_ABSOLUTE:
100 : // This relocation is ignored.
101 : break;
102 8 : case COFF::IMAGE_REL_I386_DIR32:
103 : case COFF::IMAGE_REL_I386_DIR32NB:
104 : case COFF::IMAGE_REL_I386_REL32: {
105 : RelocationEntry RE =
106 : RelocationEntry(SectionID, Offset, RelType, Addend, TargetSectionID,
107 8 : getSymbolOffset(*Symbol), 0, 0, false, 0);
108 8 : addRelocationForSection(RE, TargetSectionID);
109 : break;
110 : }
111 1 : case COFF::IMAGE_REL_I386_SECTION: {
112 : RelocationEntry RE =
113 1 : RelocationEntry(TargetSectionID, Offset, RelType, 0);
114 1 : addRelocationForSection(RE, TargetSectionID);
115 : break;
116 : }
117 2 : case COFF::IMAGE_REL_I386_SECREL: {
118 : RelocationEntry RE = RelocationEntry(SectionID, Offset, RelType,
119 2 : getSymbolOffset(*Symbol) + Addend);
120 2 : addRelocationForSection(RE, TargetSectionID);
121 : break;
122 : }
123 0 : default:
124 0 : llvm_unreachable("unsupported relocation type");
125 : }
126 :
127 : }
128 :
129 : return ++RelI;
130 : }
131 :
132 14 : void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override {
133 28 : const auto Section = Sections[RE.SectionID];
134 14 : uint8_t *Target = Section.getAddressWithOffset(RE.Offset);
135 :
136 14 : switch (RE.RelType) {
137 : case COFF::IMAGE_REL_I386_ABSOLUTE:
138 : // This relocation is ignored.
139 : break;
140 7 : case COFF::IMAGE_REL_I386_DIR32: {
141 : // The target's 32-bit VA.
142 : uint64_t Result =
143 7 : RE.Sections.SectionA == static_cast<uint32_t>(-1)
144 7 : ? Value
145 5 : : Sections[RE.Sections.SectionA].getLoadAddressWithOffset(
146 5 : RE.Addend);
147 : assert(Result <= UINT32_MAX && "relocation overflow");
148 : LLVM_DEBUG(dbgs() << "\t\tOffset: " << RE.Offset
149 : << " RelType: IMAGE_REL_I386_DIR32"
150 : << " TargetSection: " << RE.Sections.SectionA
151 : << " Value: " << format("0x%08" PRIx32, Result)
152 : << '\n');
153 7 : writeBytesUnaligned(Result, Target, 4);
154 7 : break;
155 : }
156 2 : case COFF::IMAGE_REL_I386_DIR32NB: {
157 : // The target's 32-bit RVA.
158 : // NOTE: use Section[0].getLoadAddress() as an approximation of ImageBase
159 : uint64_t Result =
160 4 : Sections[RE.Sections.SectionA].getLoadAddressWithOffset(RE.Addend) -
161 2 : Sections[0].getLoadAddress();
162 : assert(Result <= UINT32_MAX && "relocation overflow");
163 : LLVM_DEBUG(dbgs() << "\t\tOffset: " << RE.Offset
164 : << " RelType: IMAGE_REL_I386_DIR32NB"
165 : << " TargetSection: " << RE.Sections.SectionA
166 : << " Value: " << format("0x%08" PRIx32, Result)
167 : << '\n');
168 2 : writeBytesUnaligned(Result, Target, 4);
169 2 : break;
170 : }
171 2 : case COFF::IMAGE_REL_I386_REL32: {
172 : // 32-bit relative displacement to the target.
173 2 : uint64_t Result = RE.Sections.SectionA == static_cast<uint32_t>(-1)
174 2 : ? Value
175 2 : : Sections[RE.Sections.SectionA].getLoadAddress();
176 2 : Result = Result - Section.getLoadAddress() + RE.Addend - 4 - RE.Offset;
177 : assert(static_cast<int64_t>(Result) <= INT32_MAX &&
178 : "relocation overflow");
179 : assert(static_cast<int64_t>(Result) >= INT32_MIN &&
180 : "relocation underflow");
181 : LLVM_DEBUG(dbgs() << "\t\tOffset: " << RE.Offset
182 : << " RelType: IMAGE_REL_I386_REL32"
183 : << " TargetSection: " << RE.Sections.SectionA
184 : << " Value: " << format("0x%08" PRIx32, Result)
185 : << '\n');
186 2 : writeBytesUnaligned(Result, Target, 4);
187 2 : break;
188 : }
189 1 : case COFF::IMAGE_REL_I386_SECTION:
190 : // 16-bit section index of the section that contains the target.
191 : assert(static_cast<uint32_t>(RE.SectionID) <= UINT16_MAX &&
192 : "relocation overflow");
193 : LLVM_DEBUG(dbgs() << "\t\tOffset: " << RE.Offset
194 : << " RelType: IMAGE_REL_I386_SECTION Value: "
195 : << RE.SectionID << '\n');
196 1 : writeBytesUnaligned(RE.SectionID, Target, 2);
197 1 : break;
198 2 : case COFF::IMAGE_REL_I386_SECREL:
199 : // 32-bit offset of the target from the beginning of its section.
200 : assert(static_cast<uint64_t>(RE.Addend) <= UINT32_MAX &&
201 : "relocation overflow");
202 : LLVM_DEBUG(dbgs() << "\t\tOffset: " << RE.Offset
203 : << " RelType: IMAGE_REL_I386_SECREL Value: "
204 : << RE.Addend << '\n');
205 2 : writeBytesUnaligned(RE.Addend, Target, 4);
206 2 : break;
207 0 : default:
208 0 : llvm_unreachable("unsupported relocation type");
209 : }
210 14 : }
211 :
212 1 : void registerEHFrames() override {}
213 : };
214 :
215 : }
216 :
217 : #endif
218 :
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