RuntimeDyldCOFFX86_64.h revision 288943 
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                        RuntimeDyld::SymbolResolver &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.Address + 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      uint32_t *TargetAddress = (uint32_t *)Target;
76      uint64_t FinalAddress = Section.LoadAddress + RE.Offset;
77      // Delta is the distance from the start of the reloc to the end of the
78      // instruction with the reloc.
79      uint64_t Delta = 4 + (RE.RelType - COFF::IMAGE_REL_AMD64_REL32);
80      Value -= FinalAddress + Delta;
81      uint64_t Result = Value + RE.Addend;
82      assert(((int64_t)Result <= INT32_MAX) && "Relocation overflow");
83      assert(((int64_t)Result >= INT32_MIN) && "Relocation underflow");
84      *TargetAddress = Result;
85      break;
86    }
87
88    case COFF::IMAGE_REL_AMD64_ADDR32NB: {
89      // Note ADDR32NB requires a well-established notion of
90      // image base. This address must be less than or equal
91      // to every section's load address, and all sections must be
92      // within a 32 bit offset from the base.
93      //
94      // For now we just set these to zero.
95      uint32_t *TargetAddress = (uint32_t *)Target;
96      *TargetAddress = 0;
97      break;
98    }
99
100    case COFF::IMAGE_REL_AMD64_ADDR64: {
101      uint64_t *TargetAddress = (uint64_t *)Target;
102      *TargetAddress = Value + RE.Addend;
103      break;
104    }
105
106    default:
107      llvm_unreachable("Relocation type not implemented yet!");
108      break;
109    }
110  }
111
112  relocation_iterator processRelocationRef(unsigned SectionID,
113                                           relocation_iterator RelI,
114                                           const ObjectFile &Obj,
115                                           ObjSectionToIDMap &ObjSectionToID,
116                                           StubMap &Stubs) override {
117    // If possible, find the symbol referred to in the relocation,
118    // and the section that contains it.
119    symbol_iterator Symbol = RelI->getSymbol();
120    if (Symbol == Obj.symbol_end())
121      report_fatal_error("Unknown symbol in relocation");
122    section_iterator SecI(Obj.section_end());
123    Symbol->getSection(SecI);
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.ObjAddress + 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      uint32_t *Displacement = (uint32_t *)ObjTarget;
144      Addend = *Displacement;
145      break;
146    }
147
148    case COFF::IMAGE_REL_AMD64_ADDR64: {
149      uint64_t *Displacement = (uint64_t *)ObjTarget;
150      Addend = *Displacement;
151      break;
152    }
153
154    default:
155      break;
156    }
157
158    ErrorOr<StringRef> TargetNameOrErr = Symbol->getName();
159    if (std::error_code EC = TargetNameOrErr.getError())
160      report_fatal_error(EC.message());
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          findOrEmitSection(Obj, *SecI, IsCode, ObjSectionToID);
174      uint64_t TargetOffset = getSymbolOffset(*Symbol);
175      RelocationEntry RE(SectionID, Offset, RelType, TargetOffset + Addend);
176      addRelocationForSection(RE, TargetSectionID);
177    }
178
179    return ++RelI;
180  }
181
182  unsigned getStubAlignment() override { return 1; }
183  void registerEHFrames() override {
184    for (auto const &EHFrameSID : UnregisteredEHFrameSections) {
185      uint8_t *EHFrameAddr = Sections[EHFrameSID].Address;
186      uint64_t EHFrameLoadAddr = Sections[EHFrameSID].LoadAddress;
187      size_t EHFrameSize = Sections[EHFrameSID].Size;
188      MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
189      RegisteredEHFrameSections.push_back(EHFrameSID);
190    }
191    UnregisteredEHFrameSections.clear();
192  }
193  void deregisterEHFrames() override {
194    // Stub
195  }
196  void finalizeLoad(const ObjectFile &Obj,
197                    ObjSectionToIDMap &SectionMap) override {
198    // Look for and record the EH frame section IDs.
199    for (const auto &SectionPair : SectionMap) {
200      const SectionRef &Section = SectionPair.first;
201      StringRef Name;
202      Check(Section.getName(Name));
203      // Note unwind info is split across .pdata and .xdata, so this
204      // may not be sufficiently general for all users.
205      if (Name == ".xdata") {
206        UnregisteredEHFrameSections.push_back(SectionPair.second);
207      }
208    }
209  }
210};
211
212} // end namespace llvm
213
214#undef DEBUG_TYPE
215
216#endif
217