1 //===-- RuntimeDyldImpl.h - Run-time dynamic linker for MC-JIT --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Interface for the implementations of runtime dynamic linker facilities.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_RUNTIME_DYLD_IMPL_H
15 #define LLVM_RUNTIME_DYLD_IMPL_H
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/ADT/StringMap.h"
20 #include "llvm/ADT/Triple.h"
21 #include "llvm/ExecutionEngine/ObjectImage.h"
22 #include "llvm/ExecutionEngine/RuntimeDyld.h"
23 #include "llvm/Object/ObjectFile.h"
24 #include "llvm/Support/Debug.h"
25 #include "llvm/Support/ErrorHandling.h"
26 #include "llvm/Support/Format.h"
27 #include "llvm/Support/Host.h"
28 #include "llvm/Support/SwapByteOrder.h"
29 #include "llvm/Support/raw_ostream.h"
30 #include "llvm/Support/system_error.h"
34 using namespace llvm::object;
42 /// SectionEntry - represents a section emitted into memory by the dynamic
46 /// Name - section name.
49 /// Address - address in the linker's memory where the section resides.
52 /// Size - section size.
55 /// LoadAddress - the address of the section in the target process's memory.
56 /// Used for situations in which JIT-ed code is being executed in the address
57 /// space of a separate process. If the code executes in the same address
58 /// space where it was JIT-ed, this just equals Address.
61 /// StubOffset - used for architectures with stub functions for far
62 /// relocations (like ARM).
65 /// ObjAddress - address of the section in the in-memory object file. Used
66 /// for calculating relocations in some object formats (like MachO).
69 SectionEntry(StringRef name, uint8_t *address, size_t size,
70 uintptr_t stubOffset, uintptr_t objAddress)
71 : Name(name), Address(address), Size(size), LoadAddress((uintptr_t)address),
72 StubOffset(stubOffset), ObjAddress(objAddress) {}
75 /// RelocationEntry - used to represent relocations internally in the dynamic
77 class RelocationEntry {
79 /// SectionID - the section this relocation points to.
82 /// Offset - offset into the section.
85 /// RelType - relocation type.
88 /// Addend - the relocation addend encoded in the instruction itself. Also
89 /// used to make a relocation section relative instead of symbol relative.
92 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend)
93 : SectionID(id), Offset(offset), RelType(type), Addend(addend) {}
96 /// ObjRelocationInfo - relocation information as read from the object file.
97 /// Used to pass around data taken from object::RelocationRef, together with
98 /// the section to which the relocation points (represented by a SectionID).
99 class ObjRelocationInfo {
105 int64_t AdditionalInfo;
108 class RelocationValueRef {
112 const char *SymbolName;
113 RelocationValueRef(): SectionID(0), Addend(0), SymbolName(0) {}
115 inline bool operator==(const RelocationValueRef &Other) const {
116 return std::memcmp(this, &Other, sizeof(RelocationValueRef)) == 0;
118 inline bool operator <(const RelocationValueRef &Other) const {
119 return std::memcmp(this, &Other, sizeof(RelocationValueRef)) < 0;
123 class RuntimeDyldImpl {
125 // The MemoryManager to load objects into.
126 RTDyldMemoryManager *MemMgr;
128 // A list of all sections emitted by the dynamic linker. These sections are
129 // referenced in the code by means of their index in this list - SectionID.
130 typedef SmallVector<SectionEntry, 64> SectionList;
131 SectionList Sections;
133 // Keep a map of sections from object file to the SectionID which
135 typedef std::map<SectionRef, unsigned> ObjSectionToIDMap;
137 // A global symbol table for symbols from all loaded modules. Maps the
138 // symbol name to a (SectionID, offset in section) pair.
139 typedef std::pair<unsigned, uintptr_t> SymbolLoc;
140 typedef StringMap<SymbolLoc> SymbolTableMap;
141 SymbolTableMap GlobalSymbolTable;
143 // Pair representing the size and alignment requirement for a common symbol.
144 typedef std::pair<unsigned, unsigned> CommonSymbolInfo;
145 // Keep a map of common symbols to their info pairs
146 typedef std::map<SymbolRef, CommonSymbolInfo> CommonSymbolMap;
148 // For each symbol, keep a list of relocations based on it. Anytime
149 // its address is reassigned (the JIT re-compiled the function, e.g.),
150 // the relocations get re-resolved.
151 // The symbol (or section) the relocation is sourced from is the Key
152 // in the relocation list where it's stored.
153 typedef SmallVector<RelocationEntry, 64> RelocationList;
154 // Relocations to sections already loaded. Indexed by SectionID which is the
155 // source of the address. The target where the address will be written is
156 // SectionID/Offset in the relocation itself.
157 DenseMap<unsigned, RelocationList> Relocations;
159 // Relocations to external symbols that are not yet resolved. Symbols are
160 // external when they aren't found in the global symbol table of all loaded
161 // modules. This map is indexed by symbol name.
162 StringMap<RelocationList> ExternalSymbolRelocations;
164 typedef std::map<RelocationValueRef, uintptr_t> StubMap;
166 Triple::ArchType Arch;
168 inline unsigned getMaxStubSize() {
169 if (Arch == Triple::arm || Arch == Triple::thumb)
170 return 8; // 32-bit instruction and 32-bit address
171 else if (Arch == Triple::mipsel || Arch == Triple::mips)
173 else if (Arch == Triple::ppc64)
180 std::string ErrorStr;
182 // Set the error state and record an error string.
183 bool Error(const Twine &Msg) {
184 ErrorStr = Msg.str();
189 uint64_t getSectionLoadAddress(unsigned SectionID) {
190 return Sections[SectionID].LoadAddress;
193 uint8_t *getSectionAddress(unsigned SectionID) {
194 return (uint8_t*)Sections[SectionID].Address;
197 // Subclasses can override this method to get the alignment requirement of
198 // a common symbol. Returns no alignment requirement if not implemented.
199 virtual unsigned getCommonSymbolAlignment(const SymbolRef &Sym) {
204 void writeInt16BE(uint8_t *Addr, uint16_t Value) {
205 if (sys::isLittleEndianHost())
206 Value = sys::SwapByteOrder(Value);
207 *Addr = (Value >> 8) & 0xFF;
208 *(Addr+1) = Value & 0xFF;
211 void writeInt32BE(uint8_t *Addr, uint32_t Value) {
212 if (sys::isLittleEndianHost())
213 Value = sys::SwapByteOrder(Value);
214 *Addr = (Value >> 24) & 0xFF;
215 *(Addr+1) = (Value >> 16) & 0xFF;
216 *(Addr+2) = (Value >> 8) & 0xFF;
217 *(Addr+3) = Value & 0xFF;
220 void writeInt64BE(uint8_t *Addr, uint64_t Value) {
221 if (sys::isLittleEndianHost())
222 Value = sys::SwapByteOrder(Value);
223 *Addr = (Value >> 56) & 0xFF;
224 *(Addr+1) = (Value >> 48) & 0xFF;
225 *(Addr+2) = (Value >> 40) & 0xFF;
226 *(Addr+3) = (Value >> 32) & 0xFF;
227 *(Addr+4) = (Value >> 24) & 0xFF;
228 *(Addr+5) = (Value >> 16) & 0xFF;
229 *(Addr+6) = (Value >> 8) & 0xFF;
230 *(Addr+7) = Value & 0xFF;
233 /// \brief Given the common symbols discovered in the object file, emit a
234 /// new section for them and update the symbol mappings in the object and
236 void emitCommonSymbols(ObjectImage &Obj,
237 const CommonSymbolMap &CommonSymbols,
239 SymbolTableMap &SymbolTable);
241 /// \brief Emits section data from the object file to the MemoryManager.
242 /// \param IsCode if it's true then allocateCodeSection() will be
243 /// used for emits, else allocateDataSection() will be used.
244 /// \return SectionID.
245 unsigned emitSection(ObjectImage &Obj,
246 const SectionRef &Section,
249 /// \brief Find Section in LocalSections. If the secton is not found - emit
250 /// it and store in LocalSections.
251 /// \param IsCode if it's true then allocateCodeSection() will be
252 /// used for emmits, else allocateDataSection() will be used.
253 /// \return SectionID.
254 unsigned findOrEmitSection(ObjectImage &Obj,
255 const SectionRef &Section,
257 ObjSectionToIDMap &LocalSections);
259 // \brief Add a relocation entry that uses the given section.
260 void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID);
262 // \brief Add a relocation entry that uses the given symbol. This symbol may
263 // be found in the global symbol table, or it may be external.
264 void addRelocationForSymbol(const RelocationEntry &RE, StringRef SymbolName);
266 /// \brief Emits long jump instruction to Addr.
267 /// \return Pointer to the memory area for emitting target address.
268 uint8_t* createStubFunction(uint8_t *Addr);
270 /// \brief Resolves relocations from Relocs list with address from Value.
271 void resolveRelocationList(const RelocationList &Relocs, uint64_t Value);
272 void resolveRelocationEntry(const RelocationEntry &RE, uint64_t Value);
274 /// \brief A object file specific relocation resolver
275 /// \param Section The section where the relocation is being applied
276 /// \param Offset The offset into the section for this relocation
277 /// \param Value Target symbol address to apply the relocation action
278 /// \param Type object file specific relocation type
279 /// \param Addend A constant addend used to compute the value to be stored
280 /// into the relocatable field
281 virtual void resolveRelocation(const SectionEntry &Section,
287 /// \brief Parses the object file relocation and stores it to Relocations
288 /// or SymbolRelocations (this depends on the object file type).
289 virtual void processRelocationRef(const ObjRelocationInfo &Rel,
291 ObjSectionToIDMap &ObjSectionToID,
292 const SymbolTableMap &Symbols,
295 /// \brief Resolve relocations to external symbols.
296 void resolveExternalSymbols();
297 virtual ObjectImage *createObjectImage(ObjectBuffer *InputBuffer);
299 RuntimeDyldImpl(RTDyldMemoryManager *mm) : MemMgr(mm), HasError(false) {}
301 virtual ~RuntimeDyldImpl();
303 ObjectImage *loadObject(ObjectBuffer *InputBuffer);
305 void *getSymbolAddress(StringRef Name) {
306 // FIXME: Just look up as a function for now. Overly simple of course.
308 if (GlobalSymbolTable.find(Name) == GlobalSymbolTable.end())
310 SymbolLoc Loc = GlobalSymbolTable.lookup(Name);
311 return getSectionAddress(Loc.first) + Loc.second;
314 uint64_t getSymbolLoadAddress(StringRef Name) {
315 // FIXME: Just look up as a function for now. Overly simple of course.
317 if (GlobalSymbolTable.find(Name) == GlobalSymbolTable.end())
319 SymbolLoc Loc = GlobalSymbolTable.lookup(Name);
320 return getSectionLoadAddress(Loc.first) + Loc.second;
323 void resolveRelocations();
325 void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
327 void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);
329 // Is the linker in an error state?
330 bool hasError() { return HasError; }
332 // Mark the error condition as handled and continue.
333 void clearError() { HasError = false; }
335 // Get the error message.
336 StringRef getErrorString() { return ErrorStr; }
338 virtual bool isCompatibleFormat(const ObjectBuffer *Buffer) const = 0;
341 } // end namespace llvm