elf_object.hh

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/*
 * Copyright (c) 2013, 2019 ARM Limited
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 *
 * The license below extends only to copyright in the software and shall
 * not be construed as granting a license to any other intellectual
 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
 * terms below provided that you ensure that this notice is replicated
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 * modified or unmodified, in source code or in binary form.
 *
 * Copyright (c) 2003-2005 The Regents of The University of Michigan
 * All rights reserved.
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 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
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#ifndef __BASE_LOADER_ELF_OBJECT_HH__
#define __BASE_LOADER_ELF_OBJECT_HH__
 
#include <set>
#include <vector>
 
#include "base/loader/object_file.hh"
#include "gelf.h"
 
namespace Loader
{
 
class ElfObjectFormat : public ObjectFileFormat
{
  public:
    ObjectFile *load(ImageFileDataPtr data) override;
};
 
class ElfObject : public ObjectFile
{
  protected:
    Elf *elf;
    GElf_Ehdr ehdr;
 
    void determineArch();
    void determineOpSys();
    void handleLoadableSegment(GElf_Phdr phdr, int seg_num);
 
    // These values are provided to a linux process by the kernel, so we
    // need to keep them around.
    Addr _programHeaderTable = 0;
    uint16_t _programHeaderSize = 0;
    uint16_t _programHeaderCount = 0;
    std::set<std::string> sectionNames;
 
    ElfObject *interpreter = nullptr;
 
    // An interpreter load bias is the location in the process address space
    // where the interpreter is chosen to reside. Typically, this is carved
    // out of the top of the mmap reserve section.
    Addr ldBias = 0;
 
    // The interpreter is typically a relocatable shared library and will
    // have a default value of zero which means that it does not care where
    // it is placed. However, the loader can be compiled and linked so that
    // it does care and needs a specific entry point.
    bool relocate = true;
 
    // The ldMin and ldMax fields are required to know how large of an
    // area is required to map the interpreter.
    Addr ldMin = MaxAddr;
    Addr ldMax = MaxAddr;
 
    bool loadSomeSymbols(SymbolTable *symtab, int binding, Addr mask,
                         Addr base, Addr offset);
 
    void getSections();
    bool sectionExists(std::string sec);
 
    MemoryImage image;
 
  public:
    ElfObject(ImageFileDataPtr ifd);
    ~ElfObject();
 
    MemoryImage buildImage() const override { return image; }
 
    ObjectFile *getInterpreter() const override { return interpreter; }
    std::string getInterpPath(const GElf_Phdr &phdr) const;
 
    Addr bias() const override { return ldBias; }
    bool relocatable() const override { return relocate; }
    Addr mapSize() const override { return ldMax - ldMin; }
    void updateBias(Addr bias_addr) override;
 
    bool hasTLS() override { return sectionExists(".tbss"); }
 
    Addr programHeaderTable() {return _programHeaderTable;}
    uint16_t programHeaderSize() {return _programHeaderSize;}
    uint16_t programHeaderCount() {return _programHeaderCount;}
};
 
void setInterpDir(const std::string &dirname);
 
} // namespace Loader
 
#endif // __BASE_LOADER_ELF_OBJECT_HH__