1 //===-- RuntimeDyld.cpp - 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 // Implementation of the MC-JIT runtime dynamic linker.
12 //===----------------------------------------------------------------------===//
14 #define DEBUG_TYPE "dyld"
15 #include "llvm/ExecutionEngine/RuntimeDyld.h"
16 #include "ObjectImageCommon.h"
17 #include "RuntimeDyldELF.h"
18 #include "RuntimeDyldImpl.h"
19 #include "RuntimeDyldMachO.h"
20 #include "llvm/Support/FileSystem.h"
21 #include "llvm/Support/MathExtras.h"
22 #include "llvm/Object/ELF.h"
25 using namespace llvm::object;
27 // Empty out-of-line virtual destructor as the key function.
28 RuntimeDyldImpl::~RuntimeDyldImpl() {}
32 StringRef RuntimeDyldImpl::getEHFrameSection() {
36 // Resolve the relocations for all symbols we currently know about.
37 void RuntimeDyldImpl::resolveRelocations() {
38 // First, resolve relocations associated with external symbols.
39 resolveExternalSymbols();
41 // Just iterate over the sections we have and resolve all the relocations
42 // in them. Gross overkill, but it gets the job done.
43 for (int i = 0, e = Sections.size(); i != e; ++i) {
44 // The Section here (Sections[i]) refers to the section in which the
45 // symbol for the relocation is located. The SectionID in the relocation
46 // entry provides the section to which the relocation will be applied.
47 uint64_t Addr = Sections[i].LoadAddress;
48 DEBUG(dbgs() << "Resolving relocations Section #" << i
49 << "\t" << format("%p", (uint8_t *)Addr)
51 resolveRelocationList(Relocations[i], Addr);
55 void RuntimeDyldImpl::mapSectionAddress(const void *LocalAddress,
56 uint64_t TargetAddress) {
57 for (unsigned i = 0, e = Sections.size(); i != e; ++i) {
58 if (Sections[i].Address == LocalAddress) {
59 reassignSectionAddress(i, TargetAddress);
63 llvm_unreachable("Attempting to remap address of unknown section!");
66 // Subclasses can implement this method to create specialized image instances.
67 // The caller owns the pointer that is returned.
68 ObjectImage *RuntimeDyldImpl::createObjectImage(ObjectBuffer *InputBuffer) {
69 return new ObjectImageCommon(InputBuffer);
72 ObjectImage *RuntimeDyldImpl::loadObject(ObjectBuffer *InputBuffer) {
73 OwningPtr<ObjectImage> obj(createObjectImage(InputBuffer));
75 report_fatal_error("Unable to create object image from memory buffer!");
77 Arch = (Triple::ArchType)obj->getArch();
79 // Symbols found in this object
80 StringMap<SymbolLoc> LocalSymbols;
81 // Used sections from the object file
82 ObjSectionToIDMap LocalSections;
84 // Common symbols requiring allocation, with their sizes and alignments
85 CommonSymbolMap CommonSymbols;
86 // Maximum required total memory to allocate all common symbols
87 uint64_t CommonSize = 0;
91 DEBUG(dbgs() << "Parse symbols:\n");
92 for (symbol_iterator i = obj->begin_symbols(), e = obj->end_symbols();
93 i != e; i.increment(err)) {
95 object::SymbolRef::Type SymType;
97 Check(i->getType(SymType));
98 Check(i->getName(Name));
101 Check(i->getFlags(flags));
103 bool isCommon = flags & SymbolRef::SF_Common;
105 // Add the common symbols to a list. We'll allocate them all below.
107 Check(i->getAlignment(Align));
109 Check(i->getSize(Size));
110 CommonSize += Size + Align;
111 CommonSymbols[*i] = CommonSymbolInfo(Size, Align);
113 if (SymType == object::SymbolRef::ST_Function ||
114 SymType == object::SymbolRef::ST_Data ||
115 SymType == object::SymbolRef::ST_Unknown) {
117 StringRef SectionData;
119 section_iterator si = obj->end_sections();
120 Check(i->getFileOffset(FileOffset));
121 Check(i->getSection(si));
122 if (si == obj->end_sections()) continue;
123 Check(si->getContents(SectionData));
124 Check(si->isText(IsCode));
125 const uint8_t* SymPtr = (const uint8_t*)InputBuffer->getBufferStart() +
126 (uintptr_t)FileOffset;
127 uintptr_t SectOffset = (uintptr_t)(SymPtr -
128 (const uint8_t*)SectionData.begin());
129 unsigned SectionID = findOrEmitSection(*obj, *si, IsCode, LocalSections);
130 LocalSymbols[Name.data()] = SymbolLoc(SectionID, SectOffset);
131 DEBUG(dbgs() << "\tFileOffset: " << format("%p", (uintptr_t)FileOffset)
132 << " flags: " << flags
133 << " SID: " << SectionID
134 << " Offset: " << format("%p", SectOffset));
135 GlobalSymbolTable[Name] = SymbolLoc(SectionID, SectOffset);
138 DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name << "\n");
141 // Allocate common symbols
143 emitCommonSymbols(*obj, CommonSymbols, CommonSize, LocalSymbols);
145 // Parse and process relocations
146 DEBUG(dbgs() << "Parse relocations:\n");
147 for (section_iterator si = obj->begin_sections(),
148 se = obj->end_sections(); si != se; si.increment(err)) {
150 bool isFirstRelocation = true;
151 unsigned SectionID = 0;
153 section_iterator RelocatedSection = si->getRelocatedSection();
155 for (relocation_iterator i = si->begin_relocations(),
156 e = si->end_relocations(); i != e; i.increment(err)) {
159 // If it's the first relocation in this section, find its SectionID
160 if (isFirstRelocation) {
162 findOrEmitSection(*obj, *RelocatedSection, true, LocalSections);
163 DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
164 isFirstRelocation = false;
167 processRelocationRef(SectionID, *i, *obj, LocalSections, LocalSymbols,
172 // Give the subclasses a chance to tie-up any loose ends.
178 void RuntimeDyldImpl::emitCommonSymbols(ObjectImage &Obj,
179 const CommonSymbolMap &CommonSymbols,
181 SymbolTableMap &SymbolTable) {
182 // Allocate memory for the section
183 unsigned SectionID = Sections.size();
184 uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, sizeof(void*),
187 report_fatal_error("Unable to allocate memory for common symbols!");
189 Sections.push_back(SectionEntry(StringRef(), Addr, TotalSize, 0));
190 memset(Addr, 0, TotalSize);
192 DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID
193 << " new addr: " << format("%p", Addr)
194 << " DataSize: " << TotalSize
197 // Assign the address of each symbol
198 for (CommonSymbolMap::const_iterator it = CommonSymbols.begin(),
199 itEnd = CommonSymbols.end(); it != itEnd; it++) {
200 uint64_t Size = it->second.first;
201 uint64_t Align = it->second.second;
203 it->first.getName(Name);
205 // This symbol has an alignment requirement.
206 uint64_t AlignOffset = OffsetToAlignment((uint64_t)Addr, Align);
208 Offset += AlignOffset;
209 DEBUG(dbgs() << "Allocating common symbol " << Name << " address " <<
210 format("%p\n", Addr));
212 Obj.updateSymbolAddress(it->first, (uint64_t)Addr);
213 SymbolTable[Name.data()] = SymbolLoc(SectionID, Offset);
219 unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
220 const SectionRef &Section,
223 unsigned StubBufSize = 0,
224 StubSize = getMaxStubSize();
226 const ObjectFile *ObjFile = Obj.getObjectFile();
227 // FIXME: this is an inefficient way to handle this. We should computed the
228 // necessary section allocation size in loadObject by walking all the sections
231 for (section_iterator SI = ObjFile->begin_sections(),
232 SE = ObjFile->end_sections();
233 SI != SE; SI.increment(err), Check(err)) {
234 section_iterator RelSecI = SI->getRelocatedSection();
235 if (!(RelSecI == Section))
238 for (relocation_iterator I = SI->begin_relocations(),
239 E = SI->end_relocations(); I != E; I.increment(err), Check(err)) {
240 StubBufSize += StubSize;
246 uint64_t Alignment64;
247 Check(Section.getContents(data));
248 Check(Section.getAlignment(Alignment64));
250 unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
257 Check(Section.isRequiredForExecution(IsRequired));
258 Check(Section.isVirtual(IsVirtual));
259 Check(Section.isZeroInit(IsZeroInit));
260 Check(Section.isReadOnlyData(IsReadOnly));
261 Check(Section.getSize(DataSize));
262 Check(Section.getName(Name));
264 unsigned StubAlignment = getStubAlignment();
265 unsigned EndAlignment = (DataSize | Alignment) & -(DataSize | Alignment);
266 if (StubAlignment > EndAlignment)
267 StubBufSize += StubAlignment - EndAlignment;
271 unsigned SectionID = Sections.size();
273 const char *pData = 0;
275 // Some sections, such as debug info, don't need to be loaded for execution.
276 // Leave those where they are.
278 Allocate = DataSize + StubBufSize;
280 ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID)
281 : MemMgr->allocateDataSection(Allocate, Alignment, SectionID, IsReadOnly);
283 report_fatal_error("Unable to allocate section memory!");
285 // Virtual sections have no data in the object image, so leave pData = 0
289 // Zero-initialize or copy the data from the image
290 if (IsZeroInit || IsVirtual)
291 memset(Addr, 0, DataSize);
293 memcpy(Addr, pData, DataSize);
295 DEBUG(dbgs() << "emitSection SectionID: " << SectionID
297 << " obj addr: " << format("%p", pData)
298 << " new addr: " << format("%p", Addr)
299 << " DataSize: " << DataSize
300 << " StubBufSize: " << StubBufSize
301 << " Allocate: " << Allocate
303 Obj.updateSectionAddress(Section, (uint64_t)Addr);
306 // Even if we didn't load the section, we need to record an entry for it
307 // to handle later processing (and by 'handle' I mean don't do anything
308 // with these sections).
311 DEBUG(dbgs() << "emitSection SectionID: " << SectionID
313 << " obj addr: " << format("%p", data.data())
315 << " DataSize: " << DataSize
316 << " StubBufSize: " << StubBufSize
317 << " Allocate: " << Allocate
321 Sections.push_back(SectionEntry(Name, Addr, DataSize, (uintptr_t)pData));
325 unsigned RuntimeDyldImpl::findOrEmitSection(ObjectImage &Obj,
326 const SectionRef &Section,
328 ObjSectionToIDMap &LocalSections) {
330 unsigned SectionID = 0;
331 ObjSectionToIDMap::iterator i = LocalSections.find(Section);
332 if (i != LocalSections.end())
333 SectionID = i->second;
335 SectionID = emitSection(Obj, Section, IsCode);
336 LocalSections[Section] = SectionID;
341 void RuntimeDyldImpl::addRelocationForSection(const RelocationEntry &RE,
342 unsigned SectionID) {
343 Relocations[SectionID].push_back(RE);
346 void RuntimeDyldImpl::addRelocationForSymbol(const RelocationEntry &RE,
347 StringRef SymbolName) {
348 // Relocation by symbol. If the symbol is found in the global symbol table,
349 // create an appropriate section relocation. Otherwise, add it to
350 // ExternalSymbolRelocations.
351 SymbolTableMap::const_iterator Loc =
352 GlobalSymbolTable.find(SymbolName);
353 if (Loc == GlobalSymbolTable.end()) {
354 ExternalSymbolRelocations[SymbolName].push_back(RE);
356 // Copy the RE since we want to modify its addend.
357 RelocationEntry RECopy = RE;
358 RECopy.Addend += Loc->second.second;
359 Relocations[Loc->second.first].push_back(RECopy);
363 uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr) {
364 if (Arch == Triple::aarch64) {
365 // This stub has to be able to access the full address space,
366 // since symbol lookup won't necessarily find a handy, in-range,
367 // PLT stub for functions which could be anywhere.
368 uint32_t *StubAddr = (uint32_t*)Addr;
370 // Stub can use ip0 (== x16) to calculate address
371 *StubAddr = 0xd2e00010; // movz ip0, #:abs_g3:<addr>
373 *StubAddr = 0xf2c00010; // movk ip0, #:abs_g2_nc:<addr>
375 *StubAddr = 0xf2a00010; // movk ip0, #:abs_g1_nc:<addr>
377 *StubAddr = 0xf2800010; // movk ip0, #:abs_g0_nc:<addr>
379 *StubAddr = 0xd61f0200; // br ip0
382 } else if (Arch == Triple::arm) {
383 // TODO: There is only ARM far stub now. We should add the Thumb stub,
384 // and stubs for branches Thumb - ARM and ARM - Thumb.
385 uint32_t *StubAddr = (uint32_t*)Addr;
386 *StubAddr = 0xe51ff004; // ldr pc,<label>
387 return (uint8_t*)++StubAddr;
388 } else if (Arch == Triple::mipsel || Arch == Triple::mips) {
389 uint32_t *StubAddr = (uint32_t*)Addr;
390 // 0: 3c190000 lui t9,%hi(addr).
391 // 4: 27390000 addiu t9,t9,%lo(addr).
392 // 8: 03200008 jr t9.
394 const unsigned LuiT9Instr = 0x3c190000, AdduiT9Instr = 0x27390000;
395 const unsigned JrT9Instr = 0x03200008, NopInstr = 0x0;
397 *StubAddr = LuiT9Instr;
399 *StubAddr = AdduiT9Instr;
401 *StubAddr = JrT9Instr;
403 *StubAddr = NopInstr;
405 } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
406 // PowerPC64 stub: the address points to a function descriptor
407 // instead of the function itself. Load the function address
408 // on r11 and sets it to control register. Also loads the function
409 // TOC in r2 and environment pointer to r11.
410 writeInt32BE(Addr, 0x3D800000); // lis r12, highest(addr)
411 writeInt32BE(Addr+4, 0x618C0000); // ori r12, higher(addr)
412 writeInt32BE(Addr+8, 0x798C07C6); // sldi r12, r12, 32
413 writeInt32BE(Addr+12, 0x658C0000); // oris r12, r12, h(addr)
414 writeInt32BE(Addr+16, 0x618C0000); // ori r12, r12, l(addr)
415 writeInt32BE(Addr+20, 0xF8410028); // std r2, 40(r1)
416 writeInt32BE(Addr+24, 0xE96C0000); // ld r11, 0(r12)
417 writeInt32BE(Addr+28, 0xE84C0008); // ld r2, 0(r12)
418 writeInt32BE(Addr+32, 0x7D6903A6); // mtctr r11
419 writeInt32BE(Addr+36, 0xE96C0010); // ld r11, 16(r2)
420 writeInt32BE(Addr+40, 0x4E800420); // bctr
423 } else if (Arch == Triple::systemz) {
424 writeInt16BE(Addr, 0xC418); // lgrl %r1,.+8
425 writeInt16BE(Addr+2, 0x0000);
426 writeInt16BE(Addr+4, 0x0004);
427 writeInt16BE(Addr+6, 0x07F1); // brc 15,%r1
428 // 8-byte address stored at Addr + 8
430 } else if (Arch == Triple::x86_64) {
432 *(Addr+1) = 0x25; // rip
433 // 32-bit PC-relative address of the GOT entry will be stored at Addr+2
438 // Assign an address to a symbol name and resolve all the relocations
439 // associated with it.
440 void RuntimeDyldImpl::reassignSectionAddress(unsigned SectionID,
442 // The address to use for relocation resolution is not
443 // the address of the local section buffer. We must be doing
444 // a remote execution environment of some sort. Relocations can't
445 // be applied until all the sections have been moved. The client must
446 // trigger this with a call to MCJIT::finalize() or
447 // RuntimeDyld::resolveRelocations().
449 // Addr is a uint64_t because we can't assume the pointer width
450 // of the target is the same as that of the host. Just use a generic
451 // "big enough" type.
452 Sections[SectionID].LoadAddress = Addr;
455 void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
457 for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
458 const RelocationEntry &RE = Relocs[i];
459 // Ignore relocations for sections that were not loaded
460 if (Sections[RE.SectionID].Address == 0)
462 resolveRelocation(RE, Value);
466 void RuntimeDyldImpl::resolveExternalSymbols() {
467 StringMap<RelocationList>::iterator i = ExternalSymbolRelocations.begin(),
468 e = ExternalSymbolRelocations.end();
469 for (; i != e; i++) {
470 StringRef Name = i->first();
471 RelocationList &Relocs = i->second;
472 SymbolTableMap::const_iterator Loc = GlobalSymbolTable.find(Name);
473 if (Loc == GlobalSymbolTable.end()) {
474 if (Name.size() == 0) {
475 // This is an absolute symbol, use an address of zero.
476 DEBUG(dbgs() << "Resolving absolute relocations." << "\n");
477 resolveRelocationList(Relocs, 0);
479 // This is an external symbol, try to get its address from
481 uint8_t *Addr = (uint8_t*) MemMgr->getPointerToNamedFunction(Name.data(),
483 updateGOTEntries(Name, (uint64_t)Addr);
484 DEBUG(dbgs() << "Resolving relocations Name: " << Name
485 << "\t" << format("%p", Addr)
487 resolveRelocationList(Relocs, (uintptr_t)Addr);
490 report_fatal_error("Expected external symbol");
496 //===----------------------------------------------------------------------===//
497 // RuntimeDyld class implementation
498 RuntimeDyld::RuntimeDyld(RTDyldMemoryManager *mm) {
499 // FIXME: There's a potential issue lurking here if a single instance of
500 // RuntimeDyld is used to load multiple objects. The current implementation
501 // associates a single memory manager with a RuntimeDyld instance. Even
502 // though the public class spawns a new 'impl' instance for each load,
503 // they share a single memory manager. This can become a problem when page
504 // permissions are applied.
509 RuntimeDyld::~RuntimeDyld() {
513 ObjectImage *RuntimeDyld::loadObject(ObjectBuffer *InputBuffer) {
515 sys::fs::file_magic Type =
516 sys::fs::identify_magic(InputBuffer->getBuffer());
518 case sys::fs::file_magic::elf_relocatable:
519 case sys::fs::file_magic::elf_executable:
520 case sys::fs::file_magic::elf_shared_object:
521 case sys::fs::file_magic::elf_core:
522 Dyld = new RuntimeDyldELF(MM);
524 case sys::fs::file_magic::macho_object:
525 case sys::fs::file_magic::macho_executable:
526 case sys::fs::file_magic::macho_fixed_virtual_memory_shared_lib:
527 case sys::fs::file_magic::macho_core:
528 case sys::fs::file_magic::macho_preload_executable:
529 case sys::fs::file_magic::macho_dynamically_linked_shared_lib:
530 case sys::fs::file_magic::macho_dynamic_linker:
531 case sys::fs::file_magic::macho_bundle:
532 case sys::fs::file_magic::macho_dynamically_linked_shared_lib_stub:
533 case sys::fs::file_magic::macho_dsym_companion:
534 Dyld = new RuntimeDyldMachO(MM);
536 case sys::fs::file_magic::unknown:
537 case sys::fs::file_magic::bitcode:
538 case sys::fs::file_magic::archive:
539 case sys::fs::file_magic::coff_object:
540 case sys::fs::file_magic::pecoff_executable:
541 case sys::fs::file_magic::macho_universal_binary:
542 report_fatal_error("Incompatible object format!");
545 if (!Dyld->isCompatibleFormat(InputBuffer))
546 report_fatal_error("Incompatible object format!");
549 return Dyld->loadObject(InputBuffer);
552 void *RuntimeDyld::getSymbolAddress(StringRef Name) {
553 return Dyld->getSymbolAddress(Name);
556 uint64_t RuntimeDyld::getSymbolLoadAddress(StringRef Name) {
557 return Dyld->getSymbolLoadAddress(Name);
560 void RuntimeDyld::resolveRelocations() {
561 Dyld->resolveRelocations();
564 void RuntimeDyld::reassignSectionAddress(unsigned SectionID,
566 Dyld->reassignSectionAddress(SectionID, Addr);
569 void RuntimeDyld::mapSectionAddress(const void *LocalAddress,
570 uint64_t TargetAddress) {
571 Dyld->mapSectionAddress(LocalAddress, TargetAddress);
574 StringRef RuntimeDyld::getErrorString() {
575 return Dyld->getErrorString();
578 StringRef RuntimeDyld::getEHFrameSection() {
579 return Dyld->getEHFrameSection();
582 } // end namespace llvm