RuntimeDyldCOFFX86_64.h revision 314564 
1//===-- RuntimeDyldCOFFX86_64.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_x64 support for MC-JIT runtime dynamic linker.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFF86_64_H
15#define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFF86_64_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 RuntimeDyldCOFFX86_64 : public RuntimeDyldCOFF {
26
27private:
28  // When a module is loaded we save the SectionID of the unwind
29  // sections in a table until we receive a request to register all
30  // unregisteredEH frame sections with the memory manager.
31  SmallVector<SID, 2> UnregisteredEHFrameSections;
32  SmallVector<SID, 2> RegisteredEHFrameSections;
33
34public:
35  RuntimeDyldCOFFX86_64(RuntimeDyld::MemoryManager &MM,
36                        JITSymbolResolver &Resolver)
37    : RuntimeDyldCOFF(MM, Resolver) {}
38
39  unsigned getMaxStubSize() override {
40    return 6; // 2-byte jmp instruction + 32-bit relative address
41  }
42
43  // The target location for the relocation is described by RE.SectionID and
44  // RE.Offset.  RE.SectionID can be used to find the SectionEntry.  Each
45  // SectionEntry has three members describing its location.
46  // SectionEntry::Address is the address at which the section has been loaded
47  // into memory in the current (host) process.  SectionEntry::LoadAddress is
48  // the address that the section will have in the target process.
49  // SectionEntry::ObjAddress is the address of the bits for this section in the
50  // original emitted object image (also in the current address space).
51  //
52  // Relocations will be applied as if the section were loaded at
53  // SectionEntry::LoadAddress, but they will be applied at an address based
54  // on SectionEntry::Address.  SectionEntry::ObjAddress will be used to refer
55  // to Target memory contents if they are required for value calculations.
56  //
57  // The Value parameter here is the load address of the symbol for the
58  // relocation to be applied.  For relocations which refer to symbols in the
59  // current object Value will be the LoadAddress of the section in which
60  // the symbol resides (RE.Addend provides additional information about the
61  // symbol location).  For external symbols, Value will be the address of the
62  // symbol in the target address space.
63  void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override {
64    const SectionEntry &Section = Sections[RE.SectionID];
65    uint8_t *Target = Section.getAddressWithOffset(RE.Offset);
66
67    switch (RE.RelType) {
68
69    case COFF::IMAGE_REL_AMD64_REL32:
70    case COFF::IMAGE_REL_AMD64_REL32_1:
71    case COFF::IMAGE_REL_AMD64_REL32_2:
72    case COFF::IMAGE_REL_AMD64_REL32_3:
73    case COFF::IMAGE_REL_AMD64_REL32_4:
74    case COFF::IMAGE_REL_AMD64_REL32_5: {
75      uint64_t FinalAddress = Section.getLoadAddressWithOffset(RE.Offset);
76      // Delta is the distance from the start of the reloc to the end of the
77      // instruction with the reloc.
78      uint64_t Delta = 4 + (RE.RelType - COFF::IMAGE_REL_AMD64_REL32);
79      Value -= FinalAddress + Delta;
80      uint64_t Result = Value + RE.Addend;
81      assert(((int64_t)Result <= INT32_MAX) && "Relocation overflow");
82      assert(((int64_t)Result >= INT32_MIN) && "Relocation underflow");
83      writeBytesUnaligned(Result, Target, 4);
84      break;
85    }
86
87    case COFF::IMAGE_REL_AMD64_ADDR32NB: {
88      // Note ADDR32NB requires a well-established notion of
89      // image base. This address must be less than or equal
90      // to every section's load address, and all sections must be
91      // within a 32 bit offset from the base.
92      //
93      // For now we just set these to zero.
94      writeBytesUnaligned(0, Target, 4);
95      break;
96    }
97
98    case COFF::IMAGE_REL_AMD64_ADDR64: {
99      writeBytesUnaligned(Value + RE.Addend, Target, 8);
100      break;
101    }
102
103    default:
104      llvm_unreachable("Relocation type not implemented yet!");
105      break;
106    }
107  }
108
109  Expected<relocation_iterator>
110  processRelocationRef(unsigned SectionID,
111                       relocation_iterator RelI,
112                       const ObjectFile &Obj,
113                       ObjSectionToIDMap &ObjSectionToID,
114                       StubMap &Stubs) override {
115    // If possible, find the symbol referred to in the relocation,
116    // and the section that contains it.
117    symbol_iterator Symbol = RelI->getSymbol();
118    if (Symbol == Obj.symbol_end())
119      report_fatal_error("Unknown symbol in relocation");
120    auto SectionOrError = Symbol->getSection();
121    if (!SectionOrError)
122      return SectionOrError.takeError();
123    section_iterator SecI = *SectionOrError;
124    // If there is no section, this must be an external reference.
125    const bool IsExtern = SecI == Obj.section_end();
126
127    // Determine the Addend used to adjust the relocation value.
128    uint64_t RelType = RelI->getType();
129    uint64_t Offset = RelI->getOffset();
130    uint64_t Addend = 0;
131    SectionEntry &Section = Sections[SectionID];
132    uintptr_t ObjTarget = Section.getObjAddress() + Offset;
133
134    switch (RelType) {
135
136    case COFF::IMAGE_REL_AMD64_REL32:
137    case COFF::IMAGE_REL_AMD64_REL32_1:
138    case COFF::IMAGE_REL_AMD64_REL32_2:
139    case COFF::IMAGE_REL_AMD64_REL32_3:
140    case COFF::IMAGE_REL_AMD64_REL32_4:
141    case COFF::IMAGE_REL_AMD64_REL32_5:
142    case COFF::IMAGE_REL_AMD64_ADDR32NB: {
143      uint8_t *Displacement = (uint8_t *)ObjTarget;
144      Addend = readBytesUnaligned(Displacement, 4);
145      break;
146    }
147
148    case COFF::IMAGE_REL_AMD64_ADDR64: {
149      uint8_t *Displacement = (uint8_t *)ObjTarget;
150      Addend = readBytesUnaligned(Displacement, 8);
151      break;
152    }
153
154    default:
155      break;
156    }
157
158    Expected<StringRef> TargetNameOrErr = Symbol->getName();
159    if (!TargetNameOrErr)
160      return TargetNameOrErr.takeError();
161    StringRef TargetName = *TargetNameOrErr;
162
163    DEBUG(dbgs() << "\t\tIn Section " << SectionID << " Offset " << Offset
164                 << " RelType: " << RelType << " TargetName: " << TargetName
165                 << " Addend " << Addend << "\n");
166
167    if (IsExtern) {
168      RelocationEntry RE(SectionID, Offset, RelType, Addend);
169      addRelocationForSymbol(RE, TargetName);
170    } else {
171      bool IsCode = SecI->isText();
172      unsigned TargetSectionID;
173      if (auto TargetSectionIDOrErr =
174          findOrEmitSection(Obj, *SecI, IsCode, ObjSectionToID))
175        TargetSectionID = *TargetSectionIDOrErr;
176      else
177        return TargetSectionIDOrErr.takeError();
178      uint64_t TargetOffset = getSymbolOffset(*Symbol);
179      RelocationEntry RE(SectionID, Offset, RelType, TargetOffset + Addend);
180      addRelocationForSection(RE, TargetSectionID);
181    }
182
183    return ++RelI;
184  }
185
186  unsigned getStubAlignment() override { return 1; }
187  void registerEHFrames() override {
188    for (auto const &EHFrameSID : UnregisteredEHFrameSections) {
189      uint8_t *EHFrameAddr = Sections[EHFrameSID].getAddress();
190      uint64_t EHFrameLoadAddr = Sections[EHFrameSID].getLoadAddress();
191      size_t EHFrameSize = Sections[EHFrameSID].getSize();
192      MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
193      RegisteredEHFrameSections.push_back(EHFrameSID);
194    }
195    UnregisteredEHFrameSections.clear();
196  }
197  void deregisterEHFrames() override {
198    // Stub
199  }
200  Error finalizeLoad(const ObjectFile &Obj,
201                     ObjSectionToIDMap &SectionMap) override {
202    // Look for and record the EH frame section IDs.
203    for (const auto &SectionPair : SectionMap) {
204      const SectionRef &Section = SectionPair.first;
205      StringRef Name;
206      if (auto EC = Section.getName(Name))
207        return errorCodeToError(EC);
208      // Note unwind info is split across .pdata and .xdata, so this
209      // may not be sufficiently general for all users.
210      if (Name == ".xdata") {
211        UnregisteredEHFrameSections.push_back(SectionPair.second);
212      }
213    }
214    return Error::success();
215  }
216};
217
218} // end namespace llvm
219
220#undef DEBUG_TYPE
221
222#endif
223