Expose the ELFObjectFile class directly in the Object/ELF.h header, similarly

to what's done for MachO and COFF. This allows advanced uses of the class to
be implemented outside the Object library. In particular, the DyldELFObject
subclass is now moved into its logical home - ExecutionEngine/RuntimeDyld.

This patch was reviewed by Michael Spencer.




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150327 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Object/ObjectFile.h

@@ -338,8 +338,7 @@ public:
 
 public:
   static ObjectFile *createCOFFObjectFile(MemoryBuffer *Object);
-  static ObjectFile *createELFObjectFile(MemoryBuffer *Object,
-      bool doDyld = false, std::vector<uint8_t*> *MemoryMap = 0);
+  static ObjectFile *createELFObjectFile(MemoryBuffer *Object);
   static ObjectFile *createMachOObjectFile(MemoryBuffer *Object);
 };
 

lib/ExecutionEngine/RuntimeDyld/DyldELFObject.h

@@ -0,0 +1,388 @@
+//===-- DyldELFObject.h - Dynamically loaded ELF object  ----0---*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Dynamically loaded ELF object class, a subclass of ELFObjectFile. Used
+// to represent a loadable ELF image.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_RUNTIMEDYLD_DYLDELFOBJECT_H
+#define LLVM_RUNTIMEDYLD_DYLDELFOBJECT_H
+
+#include "llvm/Object/ELF.h"
+
+
+namespace llvm {
+
+using support::endianness;
+using namespace llvm::object;
+
+template<support::endianness target_endianness, bool is64Bits>
+class DyldELFObject : public ELFObjectFile<target_endianness, is64Bits> {
+  LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
+
+  typedef Elf_Shdr_Impl<target_endianness, is64Bits> Elf_Shdr;
+  typedef Elf_Sym_Impl<target_endianness, is64Bits> Elf_Sym;
+  typedef Elf_Rel_Impl<target_endianness, is64Bits, false> Elf_Rel;
+  typedef Elf_Rel_Impl<target_endianness, is64Bits, true> Elf_Rela;
+
+  typedef typename ELFObjectFile<target_endianness, is64Bits>::
+    Elf_Ehdr Elf_Ehdr;
+  Elf_Ehdr *Header;
+
+  // Update section headers according to the current location in memory
+  virtual void rebaseObject(std::vector<uint8_t*> *MemoryMap);
+  // Record memory addresses for cleanup
+  virtual void saveAddress(std::vector<uint8_t*> *MemoryMap, uint8_t *addr);
+
+protected:
+  virtual error_code getSymbolAddress(DataRefImpl Symb, uint64_t &Res) const;
+
+public:
+  DyldELFObject(MemoryBuffer *Object, std::vector<uint8_t*> *MemoryMap,
+                error_code &ec);
+
+  // Methods for type inquiry through isa, cast, and dyn_cast
+  static inline bool classof(const Binary *v) {
+    return (isa<ELFObjectFile<target_endianness, is64Bits> >(v)
+            && classof(cast<ELFObjectFile<target_endianness, is64Bits> >(v)));
+  }
+  static inline bool classof(
+      const ELFObjectFile<target_endianness, is64Bits> *v) {
+    return v->isDyldType();
+  }
+  static inline bool classof(const DyldELFObject *v) {
+    return true;
+  }
+};
+
+template<support::endianness target_endianness, bool is64Bits>
+DyldELFObject<target_endianness, is64Bits>::DyldELFObject(MemoryBuffer *Object,
+      std::vector<uint8_t*> *MemoryMap, error_code &ec)
+  : ELFObjectFile<target_endianness, is64Bits>(Object, ec)
+  , Header(0) {
+  this->isDyldELFObject = true;
+  Header = const_cast<Elf_Ehdr *>(
+      reinterpret_cast<const Elf_Ehdr *>(this->base()));
+  if (Header->e_shoff == 0)
+    return;
+
+  // Mark the image as a dynamic shared library
+  Header->e_type = ELF::ET_DYN;
+
+  rebaseObject(MemoryMap);
+}
+
+// Walk through the ELF headers, updating virtual addresses to reflect where
+// the object is currently loaded in memory
+template<support::endianness target_endianness, bool is64Bits>
+void DyldELFObject<target_endianness, is64Bits>::rebaseObject(
+    std::vector<uint8_t*> *MemoryMap) {
+  typedef typename ELFDataTypeTypedefHelper<
+          target_endianness, is64Bits>::value_type addr_type;
+
+  uint8_t *base_p = const_cast<uint8_t *>(this->base());
+  Elf_Shdr *sectionTable =
+      reinterpret_cast<Elf_Shdr *>(base_p + Header->e_shoff);
+  uint64_t numSections = this->getNumSections();
+
+  // Allocate memory space for NOBITS sections (such as .bss), which only exist
+  // in memory, but don't occupy space in the object file.
+  // Update the address in the section headers to reflect this allocation.
+  for (uint64_t index = 0; index < numSections; index++) {
+    Elf_Shdr *sec = reinterpret_cast<Elf_Shdr *>(
+        reinterpret_cast<char *>(sectionTable) + index * Header->e_shentsize);
+
+    // Only update sections that are meant to be present in program memory
+    if (sec->sh_flags & ELF::SHF_ALLOC) {
+      uint8_t *addr = base_p + sec->sh_offset;
+      if (sec->sh_type == ELF::SHT_NOBITS) {
+        addr = static_cast<uint8_t *>(calloc(sec->sh_size, 1));
+        saveAddress(MemoryMap, addr);
+      }
+      else {
+        // FIXME: Currently memory with RWX permissions is allocated. In the
+        // future, make sure that permissions are as necessary
+        if (sec->sh_flags & ELF::SHF_WRITE) {
+            // see FIXME above
+        }
+        if (sec->sh_flags & ELF::SHF_EXECINSTR) {
+            // see FIXME above
+        }
+      }
+      assert(sizeof(addr_type) == sizeof(intptr_t) &&
+             "Cross-architecture ELF dy-load is not supported!");
+      sec->sh_addr = static_cast<addr_type>(intptr_t(addr));
+    }
+  }
+
+  // Now allocate actual space for COMMON symbols, which also don't occupy
+  // space in the object file.
+  // We want to allocate space for all COMMON symbols at once, so the flow is:
+  // 1. Go over all symbols, find those that are in COMMON. For each such
+  //    symbol, record its size and the value field in its symbol header in a
+  //    special vector.
+  // 2. Allocate memory for all COMMON symbols in one fell swoop.
+  // 3. Using the recorded information from (1), update the address fields in
+  //    the symbol headers of the COMMON symbols to reflect their allocated
+  //    address.
+  uint64_t TotalSize = 0;
+  std::vector<std::pair<Elf_Addr *, uint64_t> > SymbAddrInfo;
+  error_code ec = object_error::success;
+  for (symbol_iterator si = this->begin_symbols(),
+       se = this->end_symbols(); si != se; si.increment(ec)) {
+    uint64_t Size = 0;
+    ec = si->getSize(Size);
+    Elf_Sym* symb = const_cast<Elf_Sym*>(
+        this->getSymbol(si->getRawDataRefImpl()));
+    if (ec == object_error::success &&
+        this->getSymbolTableIndex(symb) == ELF::SHN_COMMON && Size > 0) {
+      SymbAddrInfo.push_back(std::make_pair(&(symb->st_value), Size));
+      TotalSize += Size;
+    }
+  }
+
+  uint8_t* SectionPtr = (uint8_t *)calloc(TotalSize, 1);
+  saveAddress(MemoryMap, SectionPtr);
+
+  typedef typename std::vector<std::pair<Elf_Addr *, uint64_t> >::iterator
+      AddrInfoIterator;
+  AddrInfoIterator EndIter = SymbAddrInfo.end();
+  for (AddrInfoIterator AddrIter = SymbAddrInfo.begin();
+       AddrIter != EndIter; ++AddrIter) {
+    assert(sizeof(addr_type) == sizeof(intptr_t) &&
+           "Cross-architecture ELF dy-load is not supported!");
+    *(AddrIter->first) = static_cast<addr_type>(intptr_t(SectionPtr));
+    SectionPtr += AddrIter->second;
+  }
+}
+
+// Record memory addresses for callers
+template<support::endianness target_endianness, bool is64Bits>
+void DyldELFObject<target_endianness, is64Bits>::saveAddress(
+    std::vector<uint8_t*> *MemoryMap, uint8_t* addr) {
+  if (MemoryMap)
+    MemoryMap->push_back(addr);
+  else
+    errs() << "WARNING: Memory leak - cannot record memory for ELF dyld.";
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+error_code DyldELFObject<target_endianness, is64Bits>::getSymbolAddress(
+    DataRefImpl Symb, uint64_t &Result) const {
+  this->validateSymbol(Symb);
+  const Elf_Sym *symb = this->getSymbol(Symb);
+  if (this->getSymbolTableIndex(symb) == ELF::SHN_COMMON) {
+    Result = symb->st_value;
+    return object_error::success;
+  }
+  else {
+    return ELFObjectFile<target_endianness, is64Bits>::getSymbolAddress(
+        Symb, Result);
+  }
+}
+
+}
+
+#endif
+
+//===-- DyldELFObject.h - Dynamically loaded ELF object  ----0---*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Dynamically loaded ELF object class, a subclass of ELFObjectFile. Used
+// to represent a loadable ELF image.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_RUNTIMEDYLD_DYLDELFOBJECT_H
+#define LLVM_RUNTIMEDYLD_DYLDELFOBJECT_H
+
+#include "llvm/Object/ELF.h"
+
+
+namespace llvm {
+
+using support::endianness;
+using namespace llvm::object;
+
+template<support::endianness target_endianness, bool is64Bits>
+class DyldELFObject : public ELFObjectFile<target_endianness, is64Bits> {
+  LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
+
+  typedef Elf_Shdr_Impl<target_endianness, is64Bits> Elf_Shdr;
+  typedef Elf_Sym_Impl<target_endianness, is64Bits> Elf_Sym;
+  typedef Elf_Rel_Impl<target_endianness, is64Bits, false> Elf_Rel;
+  typedef Elf_Rel_Impl<target_endianness, is64Bits, true> Elf_Rela;
+
+  typedef typename ELFObjectFile<target_endianness, is64Bits>::
+    Elf_Ehdr Elf_Ehdr;
+  Elf_Ehdr *Header;
+
+  // Update section headers according to the current location in memory
+  virtual void rebaseObject(std::vector<uint8_t*> *MemoryMap);
+  // Record memory addresses for cleanup
+  virtual void saveAddress(std::vector<uint8_t*> *MemoryMap, uint8_t *addr);
+
+protected:
+  virtual error_code getSymbolAddress(DataRefImpl Symb, uint64_t &Res) const;
+
+public:
+  DyldELFObject(MemoryBuffer *Object, std::vector<uint8_t*> *MemoryMap,
+                error_code &ec);
+
+  // Methods for type inquiry through isa, cast, and dyn_cast
+  static inline bool classof(const Binary *v) {
+    return (isa<ELFObjectFile<target_endianness, is64Bits> >(v)
+            && classof(cast<ELFObjectFile<target_endianness, is64Bits> >(v)));
+  }
+  static inline bool classof(
+      const ELFObjectFile<target_endianness, is64Bits> *v) {
+    return v->isDyldType();
+  }
+  static inline bool classof(const DyldELFObject *v) {
+    return true;
+  }
+};
+
+template<support::endianness target_endianness, bool is64Bits>
+DyldELFObject<target_endianness, is64Bits>::DyldELFObject(MemoryBuffer *Object,
+      std::vector<uint8_t*> *MemoryMap, error_code &ec)
+  : ELFObjectFile<target_endianness, is64Bits>(Object, ec)
+  , Header(0) {
+  this->isDyldELFObject = true;
+  Header = const_cast<Elf_Ehdr *>(
+      reinterpret_cast<const Elf_Ehdr *>(this->base()));
+  if (Header->e_shoff == 0)
+    return;
+
+  // Mark the image as a dynamic shared library
+  Header->e_type = ELF::ET_DYN;
+
+  rebaseObject(MemoryMap);
+}
+
+// Walk through the ELF headers, updating virtual addresses to reflect where
+// the object is currently loaded in memory
+template<support::endianness target_endianness, bool is64Bits>
+void DyldELFObject<target_endianness, is64Bits>::rebaseObject(
+    std::vector<uint8_t*> *MemoryMap) {
+  typedef typename ELFDataTypeTypedefHelper<
+          target_endianness, is64Bits>::value_type addr_type;
+
+  uint8_t *base_p = const_cast<uint8_t *>(this->base());
+  Elf_Shdr *sectionTable =
+      reinterpret_cast<Elf_Shdr *>(base_p + Header->e_shoff);
+  uint64_t numSections = this->getNumSections();
+
+  // Allocate memory space for NOBITS sections (such as .bss), which only exist
+  // in memory, but don't occupy space in the object file.
+  // Update the address in the section headers to reflect this allocation.
+  for (uint64_t index = 0; index < numSections; index++) {
+    Elf_Shdr *sec = reinterpret_cast<Elf_Shdr *>(
+        reinterpret_cast<char *>(sectionTable) + index * Header->e_shentsize);
+
+    // Only update sections that are meant to be present in program memory
+    if (sec->sh_flags & ELF::SHF_ALLOC) {
+      uint8_t *addr = base_p + sec->sh_offset;
+      if (sec->sh_type == ELF::SHT_NOBITS) {
+        addr = static_cast<uint8_t *>(calloc(sec->sh_size, 1));
+        saveAddress(MemoryMap, addr);
+      }
+      else {
+        // FIXME: Currently memory with RWX permissions is allocated. In the
+        // future, make sure that permissions are as necessary
+        if (sec->sh_flags & ELF::SHF_WRITE) {
+            // see FIXME above
+        }
+        if (sec->sh_flags & ELF::SHF_EXECINSTR) {
+            // see FIXME above
+        }
+      }
+      assert(sizeof(addr_type) == sizeof(intptr_t) &&
+             "Cross-architecture ELF dy-load is not supported!");
+      sec->sh_addr = static_cast<addr_type>(intptr_t(addr));
+    }
+  }
+
+  // Now allocate actual space for COMMON symbols, which also don't occupy
+  // space in the object file.
+  // We want to allocate space for all COMMON symbols at once, so the flow is:
+  // 1. Go over all symbols, find those that are in COMMON. For each such
+  //    symbol, record its size and the value field in its symbol header in a
+  //    special vector.
+  // 2. Allocate memory for all COMMON symbols in one fell swoop.
+  // 3. Using the recorded information from (1), update the address fields in
+  //    the symbol headers of the COMMON symbols to reflect their allocated
+  //    address.
+  uint64_t TotalSize = 0;
+  std::vector<std::pair<Elf_Addr *, uint64_t> > SymbAddrInfo;
+  error_code ec = object_error::success;
+  for (symbol_iterator si = this->begin_symbols(),
+       se = this->end_symbols(); si != se; si.increment(ec)) {
+    uint64_t Size = 0;
+    ec = si->getSize(Size);
+    Elf_Sym* symb = const_cast<Elf_Sym*>(
+        this->getSymbol(si->getRawDataRefImpl()));
+    if (ec == object_error::success &&
+        this->getSymbolTableIndex(symb) == ELF::SHN_COMMON && Size > 0) {
+      SymbAddrInfo.push_back(std::make_pair(&(symb->st_value), Size));
+      TotalSize += Size;
+    }
+  }
+
+  uint8_t* SectionPtr = (uint8_t *)calloc(TotalSize, 1);
+  saveAddress(MemoryMap, SectionPtr);
+
+  typedef typename std::vector<std::pair<Elf_Addr *, uint64_t> >::iterator
+      AddrInfoIterator;
+  AddrInfoIterator EndIter = SymbAddrInfo.end();
+  for (AddrInfoIterator AddrIter = SymbAddrInfo.begin();
+       AddrIter != EndIter; ++AddrIter) {
+    assert(sizeof(addr_type) == sizeof(intptr_t) &&
+           "Cross-architecture ELF dy-load is not supported!");
+    *(AddrIter->first) = static_cast<addr_type>(intptr_t(SectionPtr));
+    SectionPtr += AddrIter->second;
+  }
+}
+
+// Record memory addresses for callers
+template<support::endianness target_endianness, bool is64Bits>
+void DyldELFObject<target_endianness, is64Bits>::saveAddress(
+    std::vector<uint8_t*> *MemoryMap, uint8_t* addr) {
+  if (MemoryMap)
+    MemoryMap->push_back(addr);
+  else
+    errs() << "WARNING: Memory leak - cannot record memory for ELF dyld.";
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+error_code DyldELFObject<target_endianness, is64Bits>::getSymbolAddress(
+    DataRefImpl Symb, uint64_t &Result) const {
+  this->validateSymbol(Symb);
+  const Elf_Sym *symb = this->getSymbol(Symb);
+  if (this->getSymbolTableIndex(symb) == ELF::SHN_COMMON) {
+    Result = symb->st_value;
+    return object_error::success;
+  }
+  else {
+    return ELFObjectFile<target_endianness, is64Bits>::getSymbolAddress(
+        Symb, Result);
+  }
+}
+
+}
+
+#endif
+