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Diffstat (limited to 'mozglue/linker/Elfxx.h')
| -rw-r--r-- | mozglue/linker/Elfxx.h | 244 |
1 files changed, 244 insertions, 0 deletions
diff --git a/mozglue/linker/Elfxx.h b/mozglue/linker/Elfxx.h new file mode 100644 index 0000000000..a871280213 --- /dev/null +++ b/mozglue/linker/Elfxx.h @@ -0,0 +1,244 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this file, + * You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifndef Elfxx_h +#define Elfxx_h + +/** + * Android system headers have two different elf.h file. The one under linux/ + * is the most complete on older Android API versions without unified headers. + */ +#if defined(ANDROID) && __ANDROID_API__ < 21 && !defined(__ANDROID_API_L__) +# include <linux/elf.h> +#else +# include <elf.h> +#endif +#include <endian.h> + +#if defined(__ARM_EABI__) && !defined(PT_ARM_EXIDX) +# define PT_ARM_EXIDX 0x70000001 +#endif + +/** + * Generic ELF macros for the target system + */ +#ifdef __LP64__ +# define Elf_(type) Elf64_##type +# define ELFCLASS ELFCLASS64 +# define ELF_R_TYPE ELF64_R_TYPE +# define ELF_R_SYM ELF64_R_SYM +# ifndef ELF_ST_BIND +# define ELF_ST_BIND ELF64_ST_BIND +# endif +#else +# define Elf_(type) Elf32_##type +# define ELFCLASS ELFCLASS32 +# define ELF_R_TYPE ELF32_R_TYPE +# define ELF_R_SYM ELF32_R_SYM +# ifndef ELF_ST_BIND +# define ELF_ST_BIND ELF32_ST_BIND +# endif +#endif + +#ifndef __BYTE_ORDER +# error Cannot find endianness +#endif + +#if __BYTE_ORDER == __LITTLE_ENDIAN +# define ELFDATA ELFDATA2LSB +#elif __BYTE_ORDER == __BIG_ENDIAN +# define ELFDATA ELFDATA2MSB +#endif + +#ifdef __linux__ +# define ELFOSABI ELFOSABI_LINUX +# ifdef EI_ABIVERSION +# define ELFABIVERSION 0 +# endif +#else +# error Unknown ELF OSABI +#endif + +#if defined(__i386__) +# define ELFMACHINE EM_386 + +// Doing this way probably doesn't scale to other architectures +# define R_ABS R_386_32 +# define R_GLOB_DAT R_386_GLOB_DAT +# define R_JMP_SLOT R_386_JMP_SLOT +# define R_RELATIVE R_386_RELATIVE +# define RELOC(n) DT_REL##n +# define UNSUPPORTED_RELOC(n) DT_RELA##n +# define STR_RELOC(n) "DT_REL" # n +# define Reloc Rel + +#elif defined(__x86_64__) +# define ELFMACHINE EM_X86_64 + +# define R_ABS R_X86_64_64 +# define R_GLOB_DAT R_X86_64_GLOB_DAT +# define R_JMP_SLOT R_X86_64_JUMP_SLOT +# define R_RELATIVE R_X86_64_RELATIVE +# define RELOC(n) DT_RELA##n +# define UNSUPPORTED_RELOC(n) DT_REL##n +# define STR_RELOC(n) "DT_RELA" # n +# define Reloc Rela + +#elif defined(__arm__) +# define ELFMACHINE EM_ARM + +# ifndef R_ARM_ABS32 +# define R_ARM_ABS32 2 +# endif +# ifndef R_ARM_GLOB_DAT +# define R_ARM_GLOB_DAT 21 +# endif +# ifndef R_ARM_JUMP_SLOT +# define R_ARM_JUMP_SLOT 22 +# endif +# ifndef R_ARM_RELATIVE +# define R_ARM_RELATIVE 23 +# endif + +# define R_ABS R_ARM_ABS32 +# define R_GLOB_DAT R_ARM_GLOB_DAT +# define R_JMP_SLOT R_ARM_JUMP_SLOT +# define R_RELATIVE R_ARM_RELATIVE +# define RELOC(n) DT_REL##n +# define UNSUPPORTED_RELOC(n) DT_RELA##n +# define STR_RELOC(n) "DT_REL" # n +# define Reloc Rel + +#elif defined(__aarch64__) +# define ELFMACHINE EM_AARCH64 + +# define R_ABS R_AARCH64_ABS64 +# define R_GLOB_DAT R_AARCH64_GLOB_DAT +# define R_JMP_SLOT R_AARCH64_JUMP_SLOT +# define R_RELATIVE R_AARCH64_RELATIVE +# define RELOC(n) DT_RELA##n +# define UNSUPPORTED_RELOC(n) DT_REL##n +# define STR_RELOC(n) "DT_RELA" # n +# define Reloc Rela + +#else +# error Unknown ELF machine type +#endif + +/** + * Android system headers don't have all definitions + */ +#ifndef STN_UNDEF +# define STN_UNDEF 0 +#endif +#ifndef DT_INIT_ARRAY +# define DT_INIT_ARRAY 25 +#endif +#ifndef DT_FINI_ARRAY +# define DT_FINI_ARRAY 26 +#endif +#ifndef DT_INIT_ARRAYSZ +# define DT_INIT_ARRAYSZ 27 +#endif +#ifndef DT_FINI_ARRAYSZ +# define DT_FINI_ARRAYSZ 28 +#endif +#ifndef DT_RELACOUNT +# define DT_RELACOUNT 0x6ffffff9 +#endif +#ifndef DT_RELCOUNT +# define DT_RELCOUNT 0x6ffffffa +#endif +#ifndef DT_VERSYM +# define DT_VERSYM 0x6ffffff0 +#endif +#ifndef DT_VERDEF +# define DT_VERDEF 0x6ffffffc +#endif +#ifndef DT_VERDEFNUM +# define DT_VERDEFNUM 0x6ffffffd +#endif +#ifndef DT_VERNEED +# define DT_VERNEED 0x6ffffffe +#endif +#ifndef DT_VERNEEDNUM +# define DT_VERNEEDNUM 0x6fffffff +#endif +#ifndef DT_FLAGS_1 +# define DT_FLAGS_1 0x6ffffffb +#endif +#ifndef DT_FLAGS +# define DT_FLAGS 30 +#endif +#ifndef DF_SYMBOLIC +# define DF_SYMBOLIC 0x00000002 +#endif +#ifndef DF_TEXTREL +# define DF_TEXTREL 0x00000004 +#endif + +namespace Elf { + +/** + * Define a few basic Elf Types + */ +typedef Elf_(Phdr) Phdr; +typedef Elf_(Dyn) Dyn; +typedef Elf_(Sym) Sym; +typedef Elf_(Addr) Addr; +typedef Elf_(Word) Word; +typedef Elf_(Half) Half; + +/** + * Helper class around the standard Elf header struct + */ +struct Ehdr : public Elf_(Ehdr) { + /** + * Equivalent to reinterpret_cast<const Ehdr *>(buf), but additionally + * checking that this is indeed an Elf header and that the Elf type + * corresponds to that of the system + */ + static const Ehdr* validate(const void* buf); +}; + +/** + * Elf String table + */ +class Strtab : public UnsizedArray<const char> { + public: + /** + * Returns the string at the given index in the table + */ + const char* GetStringAt(off_t index) const { + return &UnsizedArray<const char>::operator[](index); + } +}; + +/** + * Helper class around Elf relocation. + */ +struct Rel : public Elf_(Rel) { + /** + * Returns the addend for the relocation, which is the value stored + * at r_offset. + */ + Addr GetAddend(void* base) const { + return *(reinterpret_cast<const Addr*>(reinterpret_cast<const char*>(base) + + r_offset)); + } +}; + +/** + * Helper class around Elf relocation with addend. + */ +struct Rela : public Elf_(Rela) { + /** + * Returns the addend for the relocation. + */ + Addr GetAddend(void* base) const { return r_addend; } +}; + +} /* namespace Elf */ + +#endif /* Elfxx_h */ |