src/base/loader/elf_object.hh

   1 /*
   2  * Copyright (c) 2013, 2019 ARM Limited
   3  * All rights reserved
   4  *
   5  * The license below extends only to copyright in the software and shall
   6  * not be construed as granting a license to any other intellectual
   7  * property including but not limited to intellectual property relating
   8  * to a hardware implementation of the functionality of the software
   9  * licensed hereunder.  You may use the software subject to the license
  10  * terms below provided that you ensure that this notice is replicated
  11  * unmodified and in its entirety in all distributions of the software,
  12  * modified or unmodified, in source code or in binary form.
  13  *
  14  * Copyright (c) 2003-2005 The Regents of The University of Michigan
  15  * All rights reserved.
  16  *
  17  * Redistribution and use in source and binary forms, with or without
  18  * modification, are permitted provided that the following conditions are
  19  * met: redistributions of source code must retain the above copyright
  20  * notice, this list of conditions and the following disclaimer;
  21  * redistributions in binary form must reproduce the above copyright
  22  * notice, this list of conditions and the following disclaimer in the
  23  * documentation and/or other materials provided with the distribution;
  24  * neither the name of the copyright holders nor the names of its
  25  * contributors may be used to endorse or promote products derived from
  26  * this software without specific prior written permission.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  29  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  30  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  31  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  32  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  33  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  34  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  35  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  36  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  37  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  38  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  39  */
  40
  41 #ifndef __BASE_LOADER_ELF_OBJECT_HH__
  42 #define __BASE_LOADER_ELF_OBJECT_HH__
  43
  44 #include <set>
  45 #include <vector>
  46
  47 #include "base/loader/object_file.hh"
  48 #include "gelf.h"
  49
  50 namespace Loader
  51 {
  52
  53 class ElfObjectFormat : public ObjectFileFormat
  54 {
  55   public:
  56     ObjectFile *load(ImageFileDataPtr data) override;
  57 };
  58
  59 class ElfObject : public ObjectFile
  60 {
  61   protected:
  62     Elf *elf;
  63     GElf_Ehdr ehdr;
  64
  65     void determineArch();
  66     void determineOpSys();
  67     void handleLoadableSegment(GElf_Phdr phdr, int seg_num);
  68
  69     // These values are provided to a linux process by the kernel, so we
  70     // need to keep them around.
  71     Addr _programHeaderTable = 0;
  72     uint16_t _programHeaderSize = 0;
  73     uint16_t _programHeaderCount = 0;
  74     std::set<std::string> sectionNames;
  75
  76     ElfObject *interpreter = nullptr;
  77
  78     // An interpreter load bias is the location in the process address space
  79     // where the interpreter is chosen to reside. Typically, this is carved
  80     // out of the top of the mmap reserve section.
  81     Addr ldBias = 0;
  82
  83     // The interpreter is typically a relocatable shared library and will
  84     // have a default value of zero which means that it does not care where
  85     // it is placed. However, the loader can be compiled and linked so that
  86     // it does care and needs a specific entry point.
  87     bool relocate = true;
  88
  89     // The ldMin and ldMax fields are required to know how large of an
  90     // area is required to map the interpreter.
  91     Addr ldMin = MaxAddr;
  92     Addr ldMax = MaxAddr;
  93
  94     /// Helper functions for loadGlobalSymbols() and loadLocalSymbols().
  95     bool loadSomeSymbols(SymbolTable *symtab, int binding, Addr mask,
  96                          Addr base, Addr offset);
  97
  98     void getSections();
  99     bool sectionExists(std::string sec);
 100
 101     MemoryImage image;
 102
 103   public:
 104     ElfObject(ImageFileDataPtr ifd);
 105     ~ElfObject();
 106
 107     MemoryImage buildImage() const override { return image; }
 108
 109     ObjectFile *getInterpreter() const override { return interpreter; }
 110     std::string getInterpPath(const GElf_Phdr &phdr) const;
 111
 112     Addr bias() const override { return ldBias; }
 113     bool relocatable() const override { return relocate; }
 114     Addr mapSize() const override { return ldMax - ldMin; }
 115     void updateBias(Addr bias_addr) override;
 116
 117     bool hasTLS() override { return sectionExists(".tbss"); }
 118
 119     Addr programHeaderTable() {return _programHeaderTable;}
 120     uint16_t programHeaderSize() {return _programHeaderSize;}
 121     uint16_t programHeaderCount() {return _programHeaderCount;}
 122 };
 123
 124 /**
 125  * This is the interface for setting up a base path for the
 126  * elf interpreter. This is needed when loading a
 127  * cross-compiled (guest ISA != host ISA) dynamically
 128  * linked application.
 129  * @param dirname base path for the interpreter
 130  */
 131 void setInterpDir(const std::string &dirname);
 132
 133 } // namespace Loader
 134
 135 #endif // __BASE_LOADER_ELF_OBJECT_HH__