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    // Find the symbol referred to in the relocation, and
118    // get its section and offset.
119    //
120    // Insist for now that all symbols be resolvable within
121    // the scope of this object file.
122    symbol_iterator Symbol = RelI->getSymbol();
123    if (Symbol == Obj.symbol_end())
124      report_fatal_error("Unknown symbol in relocation");
125    unsigned TargetSectionID = 0;
126    uint64_t TargetOffset = UnknownAddressOrSize;
127    section_iterator SecI(Obj.section_end());
128    Symbol->getSection(SecI);
129    if (SecI == Obj.section_end())
130      report_fatal_error("Unknown section in relocation");
131    bool IsCode = SecI->isText();
132    TargetSectionID = findOrEmitSection(Obj, *SecI, IsCode, ObjSectionToID);
133    TargetOffset = getSymbolOffset(*Symbol);
134
135    // Determine the Addend used to adjust the relocation value.
136    uint64_t RelType;
137    Check(RelI->getType(RelType));
138    uint64_t Offset;
139    Check(RelI->getOffset(Offset));
140    uint64_t Addend = 0;
141    SectionEntry &Section = Sections[SectionID];
142    uintptr_t ObjTarget = Section.ObjAddress + Offset;
143
144    switch (RelType) {
145
146    case COFF::IMAGE_REL_AMD64_REL32:
147    case COFF::IMAGE_REL_AMD64_REL32_1:
148    case COFF::IMAGE_REL_AMD64_REL32_2:
149    case COFF::IMAGE_REL_AMD64_REL32_3:
150    case COFF::IMAGE_REL_AMD64_REL32_4:
151    case COFF::IMAGE_REL_AMD64_REL32_5:
152    case COFF::IMAGE_REL_AMD64_ADDR32NB: {
153      uint32_t *Displacement = (uint32_t *)ObjTarget;
154      Addend = *Displacement;
155      break;
156    }
157
158    case COFF::IMAGE_REL_AMD64_ADDR64: {
159      uint64_t *Displacement = (uint64_t *)ObjTarget;
160      Addend = *Displacement;
161      break;
162    }
163
164    default:
165      break;
166    }
167
168    StringRef TargetName;
169    Symbol->getName(TargetName);
170    DEBUG(dbgs() << "\t\tIn Section " << SectionID << " Offset " << Offset
171                 << " RelType: " << RelType << " TargetName: " << TargetName
172                 << " Addend " << Addend << "\n");
173
174    RelocationEntry RE(SectionID, Offset, RelType, TargetOffset + Addend);
175    addRelocationForSection(RE, TargetSectionID);
176
177    return ++RelI;
178  }
179
180  unsigned getStubAlignment() override { return 1; }
181  void registerEHFrames() override {
182    for (auto const &EHFrameSID : UnregisteredEHFrameSections) {
183      uint8_t *EHFrameAddr = Sections[EHFrameSID].Address;
184      uint64_t EHFrameLoadAddr = Sections[EHFrameSID].LoadAddress;
185      size_t EHFrameSize = Sections[EHFrameSID].Size;
186      MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
187      RegisteredEHFrameSections.push_back(EHFrameSID);
188    }
189    UnregisteredEHFrameSections.clear();
190  }
191  void deregisterEHFrames() override {
192    // Stub
193  }
194  void finalizeLoad(const ObjectFile &Obj,
195                    ObjSectionToIDMap &SectionMap) override {
196    // Look for and record the EH frame section IDs.
197    for (const auto &SectionPair : SectionMap) {
198      const SectionRef &Section = SectionPair.first;
199      StringRef Name;
200      Check(Section.getName(Name));
201      // Note unwind info is split across .pdata and .xdata, so this
202      // may not be sufficiently general for all users.
203      if (Name == ".xdata") {
204        UnregisteredEHFrameSections.push_back(SectionPair.second);
205      }
206    }
207  }
208};
209
210} // end namespace llvm
211
212#undef DEBUG_TYPE
213
214#endif
215