diff --git a/kernel/common/libELF/elf.h b/kernel/common/libELF/elf.h index 1c41ef33..8db37bea 100644 --- a/kernel/common/libELF/elf.h +++ b/kernel/common/libELF/elf.h @@ -1,6 +1,7 @@ #pragma once #include +// --> begin ==============EHDR===================== // Reference: https://docs.oracle.com/cd/E23824_01/html/819-0690/chapter6-43405.html#scrolltoc // ====== ELF32 Header中的数据类型定义 ==== @@ -19,9 +20,46 @@ typedef uint32_t Elf64_Word; typedef uint64_t Elf64_Xword; typedef uint64_t Elf64_Sxword; -// ELF Header中的最大段entry数量 +// ====== ELF Identification Index ====== +// Purpose: File identification +#define EI_MAG0 0 +#define EI_MAG1 1 +#define EI_MAG2 2 +#define EI_MAG3 3 +// Purpose: File class +#define EI_CLASS 4 +// Purpose: Data encoding +#define EI_DATA 5 +// Purpose: File version +#define EI_VERSION 6 // e_ident[EI_VERSION]指定了ELF header的版本号 当前这个值必须是EV_CURRENT + +// Purpose: Operating system/ABI identification +#define EI_OSABI 7 // e_ident[EI_OSABI]指定了操作系统以及对象所对应的ABI + +// Purpose: ABI version +#define EI_ABIVERSION 8 // e_ident[EI_ABIVERSION] 指定了对象所对应的ABI版本. + +// Purpose: Start of padding bytes +#define EI_PAD 9 // 这个值标志了e_ident中未使用字节的的起始下标 +// Purpose: Size of e_ident[] #define EI_NIDENT 16 +// EI_MAG0 - EI_MAG3 这是一个4byte的 magic number +#define ELFMAG0 0x7f +#define ELFMAG1 'E' +#define ELFMAG2 'L' +#define ELFMAG3 'F' + +// EI_CLASS e_ident[EI_CLASS]指明了文件的类型或capacity +#define ELFCLASSNONE 0 // Invalid class +#define ELFCLASS32 1 // 32–bit objects +#define ELFCLASS64 2 // 64–bit objects + +// EI_DATA e_ident[EI_DATA]指明了与处理器相关的数据的编码方式 +#define ELFDATANONE 0 +#define ELFDATA2LSB 1 // 小端对齐 +#define ELFDATA2MSB 2 // 大端对齐 + // ELF e_type的类型定义 #define ET_NONE 0 // No file type #define ET_REL 1 // Relocatable file @@ -56,8 +94,6 @@ typedef uint64_t Elf64_Sxword; #define EF_SPARCV9_RMO 0x2 // Relaxed Memory Ordering #define PN_XNUM 0xffff -#define SHN_LORESERVE 0xff00 -#define SHN_XINDEX 0xffff typedef struct { @@ -79,34 +115,246 @@ typedef struct typedef struct { - unsigned char e_ident[EI_NIDENT]; - Elf64_Half e_type; // 文件类型标志符 - Elf64_Half e_machine; // 该文件依赖的处理器架构类型 - Elf64_Word e_version; // 对象文件的版本 - Elf64_Addr e_entry; // 进程的虚拟地址入点，使用字节偏移量表示。如果没有entry point，则该值为0 - Elf64_Off e_phoff; // The program header table's file offset in bytes. 若没有，则为0 - Elf64_Off e_shoff; // The section header table's file offset in bytes. 若没有，则为0 - Elf64_Word e_flags; // 与处理器相关联的flags。格式为： EF_machine_flag 如果是x86架构，那么该值为0 - Elf64_Half e_ehsize; // ELF Header的大小（单位：字节） - Elf64_Half e_phentsize; // 程序的program header table中的一个entry的大小（所有的entry大小相同） - Elf64_Half e_phnum; // program header table的entry数量 - // e_phentsize*e_phnum=program header table的大小 - // 如果没有program header table，该值为0 - // 如果entry num>=PN_XNUM(0xffff), 那么该值为0xffff，且真实的pht的entry数量存储在section header的sh_info中（index=0） - // 其他情况下，第一个section header entry的sh_info的值为0 - + unsigned char e_ident[EI_NIDENT]; // 标志字节，这些字节与机器架构类型无关。目的是为了告诉我们如何解析这个文件的内容 + Elf64_Half e_type; // 文件类型标志符 + Elf64_Half e_machine; // 该文件依赖的处理器架构类型 + Elf64_Word e_version; // 对象文件的版本 + Elf64_Addr e_entry; // 进程的虚拟地址入点，使用字节偏移量表示。如果没有entry point，则该值为0 + Elf64_Off e_phoff; // The program header table's file offset in bytes. 若没有，则为0 + Elf64_Off e_shoff; // The section header table's file offset in bytes. 若没有，则为0 + Elf64_Word e_flags; // 与处理器相关联的flags。格式为： EF_machine_flag 如果是x86架构，那么该值为0 + Elf64_Half e_ehsize; // ELF Header的大小（单位：字节） + Elf64_Half e_phentsize; // 程序的program header table中的一个entry的大小（所有的entry大小相同） + Elf64_Half e_phnum; // program header table的entry数量 + // e_phentsize*e_phnum=program header table的大小 + // 如果没有program header table，该值为0 + // 如果entry num>=PN_XNUM(0xffff), 那么该值为0xffff，且真实的pht的entry数量存储在section header的sh_info中（index=0） + // 其他情况下，第一个section header entry的sh_info的值为0 + Elf64_Half e_shentsize; // 每个section header的大小（字节 // 每个section header是section header table的一个entry - + Elf64_Half e_shnum; // section header table的entry数量 // e_shentsize*e_shnum=section header table的大小 // 如果没有section header table，那么该值为0 // 如果section的数量>=SHN_LORESERVE(0xff00)，那么该值为0，且真实的section数量存储在 // section header at index 0的sh_size变量中，否则第一个sh_size为0 - + Elf64_Half e_shstrndx; // 与section name string表相关联的section header table的entry的索引下标 - // 如果没有name string table,那么该值等于SHN_UNDEF - // 如果对应的index>=SHN_LORESERVE(0xff00)， 那么该变量值为SHN_XINDEX(0xffff) - // 且真正的section name string table的index被存放在section header的index=0处的sh_link变量中 - // 否则初始section header entry的sh_link变量为0 + // 如果没有name string table,那么该值等于SHN_UNDEF + // 如果对应的index>=SHN_LORESERVE(0xff00)， 那么该变量值为SHN_XINDEX(0xffff) + // 且真正的section name string table的index被存放在section header的index=0处的sh_link变量中 + // 否则初始section header entry的sh_link变量为0 } Elf64_Ehdr; + +// --> end ==============EHDR===================== + +// --> begin ==============SHDR===================== + +// reference: https://docs.oracle.com/cd/E23824_01/html/819-0690/chapter6-94076.html#scrolltoc + +// ===== ELF Special Section Indexes ===== +#define SHN_UNDEF 0 // An undefined, missing, irrelevant, or otherwise meaningless section reference. +#define SHN_LORESERVE 0xff00 // The lower boundary of the range of reserved indexes. + // The system reserves indexes between SHN_LORESERVE and SHN_HIRESERVE, inclusive. +#define SHN_LOPROC 0xff00 // SHN_LOPROC - SHN_HIPROC 这个范围以内的数据为处理器特定的语义所保留 +#define SHN_BEFORE 0xff00 // SHN_BEFORE, SHN_AFTER 与SHF_LINK_ORDER及SHF_ORDERED section flags一起，提供初始和终止section的 +#define SHN_AFTER 0xff01 +#define SHN_AMD64_LCOMMON 0xff02 // x64 specific common block label. This label is similar to SHN_COMMON, but provides for identifying a large common block. +#define SHN_HIPROC 0xff1f +#define SHN_LOOS 0xff20 // SHN_LOOS - SHN_HIOS 这个范围你的数为操作系统特定的语义所保留 +#define SHN_LOSUNW 0xff3f // SHN_LOSUNW - SHN_HISUNW Values in this inclusive range are reserved for Sun-specific semantics. +#define SHN_SUNW_IGNORE 0xff3f // This section index provides a temporary symbol definition within relocatable objects. Reserved for internal use by dtrace(1M). +#define SHN_HISUNW 0xff3f +#define SHN_HIOS 0xff3f +#define SHN_ABS 0xfff1 // 对应的引用的绝对值。 举个例子，symbols defined relative to section number SHN_ABS have absolute values and are not affected by relocation. +#define SHN_COMMON 0xfff2 // Symbols defined relative to this section are common symbols +#define SHN_XINDEX 0xffff +#define SHN_HIRESERVE 0xffff // The upper boundary of the range of reserved indexes. +/* +Note - + Although index 0 is reserved as the undefined value, + the section header table contains an entry for index 0. + That is, if the e_shnum member of the ELF header indicates + a file has 6 entries in the section header table, the sections + have the indexes 0 through 5. The contents of the initial entry + are specified later in this section. +*/ + +typedef struct +{ + Elf32_Word sh_name; + Elf32_Word sh_type; + Elf32_Word sh_flags; + Elf32_Addr sh_addr; + Elf32_Off sh_offset; + Elf32_Word sh_size; + Elf32_Word sh_link; + Elf32_Word sh_info; + Elf32_Word sh_addralign; + Elf32_Word sh_entsize; +} Elf32_Shdr; + +typedef struct +{ + Elf64_Word sh_name; // 段名 + Elf64_Word sh_type; // 段的类型（按照内容和语义来分类） + Elf64_Xword sh_flags; + Elf64_Addr sh_addr; // 该section在进程的内存空间中的基地址。如果该段不需要出现在内存中，该值为0 + Elf64_Off sh_offset; // The byte offset from the beginning of the file to the first byte in the section + // 对于一个 SHT_NOBITS section，这个变量指的是概念上的偏移量。因为这种段并不是真正存在于文件中 + Elf64_Xword sh_size; // The section's size in bytes(如果是SHT_NOBITS类型的section，section不会在文件中真正占用sh_size的空间) + Elf64_Word sh_link; // A section header table index link, whose interpretation depends on the section type. + Elf64_Word sh_info; // 依赖于section type来解析的额外的信息。如果sh_flags有SHF_INFO_LINK属性，那么这个变量代表一个section header table index. + Elf64_Xword sh_addralign; // 地址按照多少bytes对齐。只允许使用2的n次幂的值。如果值为0或1，则意味着地址没有对齐要求。 + Elf64_Xword sh_entsize; // 如果某个段拥有指定size的entry，则在这里指定，否则为0 +} Elf64_Shdr; + +// ELF Section Types, sh_type +#define SHT_NULL 0 +#define SHT_PROGBITS 1 +#define SHT_SYMTAB 2 // Identifies a symbol table +#define SHT_STRTAB 3 // Identifies a string table. +#define SHT_RELA 4 +#define SHT_HASH 5 +#define SHT_DYNAMIC 6 +#define SHT_NOTE 7 +#define SHT_NOBITS 8 +#define SHT_REL 9 +#define SHT_SHLIB 10 +#define SHT_DYNSYM 11 // Identifies a symbol table +#define SHT_INIT_ARRAY 14 +#define SHT_FINI_ARRAY 15 +#define SHT_PREINIT_ARRAY 16 +#define SHT_GROUP 17 +#define SHT_SYMTAB_SHNDX 18 +#define SHT_LOOS 0x60000000 +#define SHT_LOSUNW 0x6fffffef +#define SHT_SUNW_capchain 0x6fffffef +#define SHT_SUNW_capinfo 0x6ffffff0 +#define SHT_SUNW_symsort 0x6ffffff1 +#define SHT_SUNW_tlssort 0x6ffffff2 +#define SHT_SUNW_LDYNSYM 0x6ffffff3 // Identifies a symbol table +#define SHT_SUNW_dof 0x6ffffff4 +#define SHT_SUNW_cap 0x6ffffff5 +#define SHT_SUNW_SIGNATURE 0x6ffffff6 +#define SHT_SUNW_ANNOTATE 0x6ffffff7 +#define SHT_SUNW_DEBUGSTR 0x6ffffff8 +#define SHT_SUNW_DEBUG 0x6ffffff9 +#define SHT_SUNW_move 0x6ffffffa +#define SHT_SUNW_COMDAT 0x6ffffffb +#define SHT_SUNW_syminfo 0x6ffffffc +#define SHT_SUNW_verdef 0x6ffffffd +#define SHT_SUNW_verneed 0x6ffffffe +#define SHT_SUNW_versym 0x6fffffff +#define SHT_HISUNW 0x6fffffff +#define SHT_HIOS 0x6fffffff +#define SHT_LOPROC 0x70000000 +#define SHT_SPARC_GOTDATA 0x70000000 +#define SHT_AMD64_UNWIND 0x70000001 +#define SHT_HIPROC 0x7fffffff +#define SHT_LOUSER 0x80000000 +#define SHT_HIUSER 0xffffffff + +// ELF Section Attribute Flags +#define SHF_WRITE 0x1 // Identifies a section that should be writable during process execution +#define SHF_ALLOC 0x2 // Identifies a section that occupies memory during process execution +#define SHF_EXECINSTR 0x4 // contains executable machine instructions +#define SHF_MERGE 0x10 +#define SHF_STRINGS 0x20 +#define SHF_INFO_LINK 0x40 // This section headers sh_info field holds a section header table index +#define SHF_LINK_ORDER 0x80 // This section adds special ordering requirements to the link-editor +#define SHF_OS_NONCONFORMING 0x100 +#define SHF_GROUP 0x200 +#define SHF_TLS 0x400 +#define SHF_MASKOS 0x0ff00000 +#define SHF_AMD64_LARGE 0x10000000 // identifies a section that can hold more than 2 Gbyte +#define SHF_ORDERED 0x40000000 +#define SHF_EXCLUDE 0x80000000 +#define SHF_MASKPROC 0xf0000000 + +// --> end ==============SHDR===================== + +// --> begin ========== symbol table section ====== +typedef struct +{ + Elf32_Word st_name; + Elf32_Addr st_value; + Elf32_Word st_size; + unsigned char st_info; + unsigned char st_other; + Elf32_Half st_shndx; +} Elf32_Sym; +typedef struct +{ + Elf64_Word st_name; + unsigned char st_info; + unsigned char st_other; + Elf64_Half st_shndx; + Elf64_Addr st_value; + Elf64_Xword st_size; +} Elf64_Sym; + +// --> end ========== symbol table section ====== + +// --> begin ========== program header ========= +// Ref: https://docs.oracle.com/cd/E23824_01/html/819-0690/chapter6-83432.html#scrolltoc + +typedef struct +{ + Elf32_Word p_type; + Elf32_Off p_offset; + Elf32_Addr p_vaddr; + Elf32_Addr p_paddr; + Elf32_Word p_filesz; + Elf32_Word p_memsz; + Elf32_Word p_flags; + Elf32_Word p_align; +} Elf32_Phdr; + +typedef struct +{ + Elf64_Word p_type; + Elf64_Word p_flags; + Elf64_Off p_offset; + Elf64_Addr p_vaddr; + Elf64_Addr p_paddr; + Elf64_Xword p_filesz; + Elf64_Xword p_memsz; + Elf64_Xword p_align; +} Elf64_Phdr; + +// ELF segment types +#define PT_NULL 0 +#define PT_LOAD 1 // Specifies a loadable segment +#define PT_DYNAMIC 2 // Specifies dynamic linking information. +#define PT_INTERP 3 // Specifies the location and size of a null-terminated path name to invoke as an interpreter +#define PT_NOTE 4 // Specifies the location and size of auxiliary information +#define PT_SHLIB 5 +#define PT_PHDR 6 // Specifies the location and size of the program header table +#define PT_TLS 7 // Specifies a thread-local storage template +/* +PT_LOOS - PT_HIOS +Values in this inclusive range are reserved for OS-specific semantics. +*/ +#define PT_LOOS 0x60000000 +#define PT_SUNW_UNWIND 0x6464e550 +#define PT_SUNW_EH_FRAME 0x6474e550 +#define PT_LOSUNW 0x6ffffffa +#define PT_SUNWBSS 0x6ffffffa +#define PT_SUNWSTACK 0x6ffffffb +#define PT_SUNWDTRACE 0x6ffffffc +#define PT_SUNWCAP 0x6ffffffd +#define PT_HISUNW 0x6fffffff +#define PT_HIOS 0x6fffffff +#define PT_LOPROC 0x70000000 +#define PT_HIPROC 0x7fffffff + +// ELF Segment Flags +#define PF_X 0x1 // Execute +#define PF_W 0x2 // Write +#define PF_R 0x4 // Read +#define PF_MASKPROC 0xf0000000 // Unspecified + + +// --> end ========== program header ========= \ No newline at end of file