RuntimeDyldCOFFI386.h revision 292915 
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 "llvm/Object/COFF.h"
18#include "llvm/Support/COFF.h"
19#include "../RuntimeDyldCOFF.h"
20
21#define DEBUG_TYPE "dyld"
22
23namespace llvm {
24
25class RuntimeDyldCOFFI386 : public RuntimeDyldCOFF {
26public:
27  RuntimeDyldCOFFI386(RuntimeDyld::MemoryManager &MM,
28                      RuntimeDyld::SymbolResolver &Resolver)
29      : RuntimeDyldCOFF(MM, Resolver) {}
30
31  unsigned getMaxStubSize() override {
32    return 8; // 2-byte jmp instruction + 32-bit relative address + 2 byte pad
33  }
34
35  unsigned getStubAlignment() override { return 1; }
36
37  relocation_iterator processRelocationRef(unsigned SectionID,
38                                           relocation_iterator RelI,
39                                           const ObjectFile &Obj,
40                                           ObjSectionToIDMap &ObjSectionToID,
41                                           StubMap &Stubs) override {
42    auto Symbol = RelI->getSymbol();
43    if (Symbol == Obj.symbol_end())
44      report_fatal_error("Unknown symbol in relocation");
45
46    ErrorOr<StringRef> TargetNameOrErr = Symbol->getName();
47    if (auto EC = TargetNameOrErr.getError())
48      report_fatal_error(EC.message());
49    StringRef TargetName = *TargetNameOrErr;
50
51    auto Section = *Symbol->getSection();
52
53    uint64_t RelType = RelI->getType();
54    uint64_t Offset = RelI->getOffset();
55
56#if !defined(NDEBUG)
57    SmallString<32> RelTypeName;
58    RelI->getTypeName(RelTypeName);
59#endif
60    DEBUG(dbgs() << "\t\tIn Section " << SectionID << " Offset " << Offset
61                 << " RelType: " << RelTypeName << " TargetName: " << TargetName
62                 << "\n");
63
64    unsigned TargetSectionID = -1;
65    if (Section == Obj.section_end()) {
66      RelocationEntry RE(SectionID, Offset, RelType, 0, -1, 0, 0, 0, false, 0);
67      addRelocationForSymbol(RE, TargetName);
68    } else {
69      TargetSectionID =
70          findOrEmitSection(Obj, *Section, Section->isText(), ObjSectionToID);
71
72      switch (RelType) {
73      case COFF::IMAGE_REL_I386_ABSOLUTE:
74        // This relocation is ignored.
75        break;
76      case COFF::IMAGE_REL_I386_DIR32:
77      case COFF::IMAGE_REL_I386_DIR32NB:
78      case COFF::IMAGE_REL_I386_REL32: {
79        RelocationEntry RE =
80            RelocationEntry(SectionID, Offset, RelType, 0, TargetSectionID,
81                            getSymbolOffset(*Symbol), 0, 0, false, 0);
82        addRelocationForSection(RE, TargetSectionID);
83        break;
84      }
85      case COFF::IMAGE_REL_I386_SECTION: {
86        RelocationEntry RE =
87            RelocationEntry(TargetSectionID, Offset, RelType, 0);
88        addRelocationForSection(RE, TargetSectionID);
89        break;
90      }
91      case COFF::IMAGE_REL_I386_SECREL: {
92        RelocationEntry RE = RelocationEntry(SectionID, Offset, RelType,
93                                             getSymbolOffset(*Symbol));
94        addRelocationForSection(RE, TargetSectionID);
95        break;
96      }
97      default:
98        llvm_unreachable("unsupported relocation type");
99      }
100
101    }
102
103    return ++RelI;
104  }
105
106  void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override {
107    const auto Section = Sections[RE.SectionID];
108    uint8_t *Target = Section.getAddressWithOffset(RE.Offset);
109
110    switch (RE.RelType) {
111    case COFF::IMAGE_REL_I386_ABSOLUTE:
112      // This relocation is ignored.
113      break;
114    case COFF::IMAGE_REL_I386_DIR32: {
115      // The target's 32-bit VA.
116      uint64_t Result =
117          RE.Sections.SectionA == static_cast<uint32_t>(-1)
118              ? Value
119              : Sections[RE.Sections.SectionA].getLoadAddressWithOffset(
120                    RE.Addend);
121      assert(static_cast<int32_t>(Result) <= INT32_MAX &&
122             "relocation overflow");
123      assert(static_cast<int32_t>(Result) >= INT32_MIN &&
124             "relocation underflow");
125      DEBUG(dbgs() << "\t\tOffset: " << RE.Offset
126                   << " RelType: IMAGE_REL_I386_DIR32"
127                   << " TargetSection: " << RE.Sections.SectionA
128                   << " Value: " << format("0x%08" PRIx32, Result) << '\n');
129      writeBytesUnaligned(Result, Target, 4);
130      break;
131    }
132    case COFF::IMAGE_REL_I386_DIR32NB: {
133      // The target's 32-bit RVA.
134      // NOTE: use Section[0].getLoadAddress() as an approximation of ImageBase
135      uint64_t Result =
136          Sections[RE.Sections.SectionA].getLoadAddressWithOffset(RE.Addend) -
137          Sections[0].getLoadAddress();
138      assert(static_cast<int32_t>(Result) <= INT32_MAX &&
139             "relocation overflow");
140      assert(static_cast<int32_t>(Result) >= INT32_MIN &&
141             "relocation underflow");
142      DEBUG(dbgs() << "\t\tOffset: " << RE.Offset
143                   << " RelType: IMAGE_REL_I386_DIR32NB"
144                   << " TargetSection: " << RE.Sections.SectionA
145                   << " Value: " << format("0x%08" PRIx32, Result) << '\n');
146      writeBytesUnaligned(Result, Target, 4);
147      break;
148    }
149    case COFF::IMAGE_REL_I386_REL32: {
150      // 32-bit relative displacement to the target.
151      uint64_t Result = Sections[RE.Sections.SectionA].getLoadAddress() -
152                        Section.getLoadAddress() + RE.Addend - 4 - RE.Offset;
153      assert(static_cast<int32_t>(Result) <= INT32_MAX &&
154             "relocation overflow");
155      assert(static_cast<int32_t>(Result) >= INT32_MIN &&
156             "relocation underflow");
157      DEBUG(dbgs() << "\t\tOffset: " << RE.Offset
158                   << " RelType: IMAGE_REL_I386_REL32"
159                   << " TargetSection: " << RE.Sections.SectionA
160                   << " Value: " << format("0x%08" PRIx32, Result) << '\n');
161      writeBytesUnaligned(Result, Target, 4);
162      break;
163    }
164    case COFF::IMAGE_REL_I386_SECTION:
165      // 16-bit section index of the section that contains the target.
166      assert(static_cast<int32_t>(RE.SectionID) <= INT16_MAX &&
167             "relocation overflow");
168      assert(static_cast<int32_t>(RE.SectionID) >= INT16_MIN &&
169             "relocation underflow");
170      DEBUG(dbgs() << "\t\tOffset: " << RE.Offset
171                   << " RelType: IMAGE_REL_I386_SECTION Value: " << RE.SectionID
172                   << '\n');
173      writeBytesUnaligned(RE.SectionID, Target, 2);
174      break;
175    case COFF::IMAGE_REL_I386_SECREL:
176      // 32-bit offset of the target from the beginning of its section.
177      assert(static_cast<int32_t>(RE.Addend) <= INT32_MAX &&
178             "relocation overflow");
179      assert(static_cast<int32_t>(RE.Addend) >= INT32_MIN &&
180             "relocation underflow");
181      DEBUG(dbgs() << "\t\tOffset: " << RE.Offset
182                   << " RelType: IMAGE_REL_I386_SECREL Value: " << RE.Addend
183                   << '\n');
184      writeBytesUnaligned(RE.Addend, Target, 2);
185      break;
186    default:
187      llvm_unreachable("unsupported relocation type");
188    }
189  }
190
191  void registerEHFrames() override {}
192  void deregisterEHFrames() override {}
193
194  void finalizeLoad(const ObjectFile &Obj,
195                    ObjSectionToIDMap &SectionMap) override {}
196};
197
198}
199
200#endif
201
202