1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/mozglue/linker/CustomElf.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,209 @@
1.4 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.5 + * License, v. 2.0. If a copy of the MPL was not distributed with this file,
1.6 + * You can obtain one at http://mozilla.org/MPL/2.0/. */
1.7 +
1.8 +#ifndef CustomElf_h
1.9 +#define CustomElf_h
1.10 +
1.11 +#include "ElfLoader.h"
1.12 +#include "Logging.h"
1.13 +#include "Elfxx.h"
1.14 +
1.15 +/**
1.16 + * Library Handle class for ELF libraries we don't let the system linker
1.17 + * handle.
1.18 + */
1.19 +class CustomElf: public LibHandle, private ElfLoader::link_map
1.20 +{
1.21 + friend class ElfLoader;
1.22 + friend class SEGVHandler;
1.23 +public:
1.24 + /**
1.25 + * Returns a new CustomElf using the given file descriptor to map ELF
1.26 + * content. The file descriptor ownership is stolen, and it will be closed
1.27 + * in CustomElf's destructor if an instance is created, or by the Load
1.28 + * method otherwise. The path corresponds to the file descriptor, and flags
1.29 + * are the same kind of flags that would be given to dlopen(), though
1.30 + * currently, none are supported and the behaviour is more or less that of
1.31 + * RTLD_GLOBAL | RTLD_BIND_NOW.
1.32 + */
1.33 + static mozilla::TemporaryRef<LibHandle> Load(Mappable *mappable,
1.34 + const char *path, int flags);
1.35 +
1.36 + /**
1.37 + * Inherited from LibHandle
1.38 + */
1.39 + virtual ~CustomElf();
1.40 + virtual void *GetSymbolPtr(const char *symbol) const;
1.41 + virtual bool Contains(void *addr) const;
1.42 +
1.43 +#ifdef __ARM_EABI__
1.44 + virtual const void *FindExidx(int *pcount) const;
1.45 +#endif
1.46 +
1.47 +protected:
1.48 + virtual Mappable *GetMappable() const;
1.49 +
1.50 +public:
1.51 + /**
1.52 + * Shows some stats about the Mappable instance. The when argument is to be
1.53 + * used by the caller to give an identifier of the when the stats call is
1.54 + * made.
1.55 + */
1.56 + void stats(const char *when) const;
1.57 +
1.58 +private:
1.59 + /**
1.60 + * Returns a pointer to the Elf Symbol in the Dynamic Symbol table
1.61 + * corresponding to the given symbol name (with a pre-computed hash).
1.62 + */
1.63 + const Elf::Sym *GetSymbol(const char *symbol, unsigned long hash) const;
1.64 +
1.65 + /**
1.66 + * Returns the address corresponding to the given symbol name (with a
1.67 + * pre-computed hash).
1.68 + */
1.69 + void *GetSymbolPtr(const char *symbol, unsigned long hash) const;
1.70 +
1.71 + /**
1.72 + * Scan dependent libraries to find the address corresponding to the
1.73 + * given symbol name. This is used to find symbols that are undefined
1.74 + * in the Elf object.
1.75 + */
1.76 + void *GetSymbolPtrInDeps(const char *symbol) const;
1.77 +
1.78 + /**
1.79 + * Private constructor
1.80 + */
1.81 + CustomElf(Mappable *mappable, const char *path)
1.82 + : LibHandle(path)
1.83 + , mappable(mappable)
1.84 + , init(0)
1.85 + , fini(0)
1.86 + , initialized(false)
1.87 + , has_text_relocs(false)
1.88 + { }
1.89 +
1.90 + /**
1.91 + * Returns a pointer relative to the base address where the library is
1.92 + * loaded.
1.93 + */
1.94 + void *GetPtr(const Elf::Addr offset) const
1.95 + {
1.96 + return base + offset;
1.97 + }
1.98 +
1.99 + /**
1.100 + * Like the above, but returns a typed (const) pointer
1.101 + */
1.102 + template <typename T>
1.103 + const T *GetPtr(const Elf::Addr offset) const
1.104 + {
1.105 + return reinterpret_cast<const T *>(base + offset);
1.106 + }
1.107 +
1.108 + /**
1.109 + * Loads an Elf segment defined by the given PT_LOAD header.
1.110 + * Returns whether this succeeded or failed.
1.111 + */
1.112 + bool LoadSegment(const Elf::Phdr *pt_load) const;
1.113 +
1.114 + /**
1.115 + * Initializes the library according to information found in the given
1.116 + * PT_DYNAMIC header.
1.117 + * Returns whether this succeeded or failed.
1.118 + */
1.119 + bool InitDyn(const Elf::Phdr *pt_dyn);
1.120 +
1.121 + /**
1.122 + * Apply .rel.dyn/.rela.dyn relocations.
1.123 + * Returns whether this succeeded or failed.
1.124 + */
1.125 + bool Relocate();
1.126 +
1.127 + /**
1.128 + * Apply .rel.plt/.rela.plt relocations.
1.129 + * Returns whether this succeeded or failed.
1.130 + */
1.131 + bool RelocateJumps();
1.132 +
1.133 + /**
1.134 + * Call initialization functions (.init/.init_array)
1.135 + * Returns true;
1.136 + */
1.137 + bool CallInit();
1.138 +
1.139 + /**
1.140 + * Call destructor functions (.fini_array/.fini)
1.141 + * Returns whether this succeeded or failed.
1.142 + */
1.143 + void CallFini();
1.144 +
1.145 + /**
1.146 + * Call a function given a pointer to its location.
1.147 + */
1.148 + void CallFunction(void *ptr) const
1.149 + {
1.150 + /* C++ doesn't allow direct conversion between pointer-to-object
1.151 + * and pointer-to-function. */
1.152 + union {
1.153 + void *ptr;
1.154 + void (*func)(void);
1.155 + } f;
1.156 + f.ptr = ptr;
1.157 + DEBUG_LOG("%s: Calling function @%p", GetPath(), ptr);
1.158 + f.func();
1.159 + }
1.160 +
1.161 + /**
1.162 + * Call a function given a an address relative to the library base
1.163 + */
1.164 + void CallFunction(Elf::Addr addr) const
1.165 + {
1.166 + return CallFunction(GetPtr(addr));
1.167 + }
1.168 +
1.169 + /* Appropriated Mappable */
1.170 + mozilla::RefPtr<Mappable> mappable;
1.171 +
1.172 + /* Base address where the library is loaded */
1.173 + MappedPtr base;
1.174 +
1.175 + /* String table */
1.176 + Elf::Strtab strtab;
1.177 +
1.178 + /* Symbol table */
1.179 + UnsizedArray<Elf::Sym> symtab;
1.180 +
1.181 + /* Buckets and chains for the System V symbol hash table */
1.182 + Array<Elf::Word> buckets;
1.183 + UnsizedArray<Elf::Word> chains;
1.184 +
1.185 + /* List of dependent libraries */
1.186 + std::vector<mozilla::RefPtr<LibHandle> > dependencies;
1.187 +
1.188 + /* List of .rel.dyn/.rela.dyn relocations */
1.189 + Array<Elf::Reloc> relocations;
1.190 +
1.191 + /* List of .rel.plt/.rela.plt relocation */
1.192 + Array<Elf::Reloc> jumprels;
1.193 +
1.194 + /* Relative address of the initialization and destruction functions
1.195 + * (.init/.fini) */
1.196 + Elf::Addr init, fini;
1.197 +
1.198 + /* List of initialization and destruction functions
1.199 + * (.init_array/.fini_array) */
1.200 + Array<void *> init_array, fini_array;
1.201 +
1.202 + bool initialized;
1.203 +
1.204 + bool has_text_relocs;
1.205 +
1.206 +#ifdef __ARM_EABI__
1.207 + /* ARM.exidx information used by FindExidx */
1.208 + Array<uint32_t[2]> arm_exidx;
1.209 +#endif
1.210 +};
1.211 +
1.212 +#endif /* CustomElf_h */
