linux remoteproc驱动中elf解析函数实现分析
1 ELF文件组织结构2 ELF_GEN_FIELD_GET_SET3 elf 各种header解析接口以及其实现3.1 elf header3.1.1 elf header解析接口3.1.2 elf header各个解析函数为：3.1.2.1 ELF_GEN_FIELD_GET_SET(hdr, e_entry, u64)3.1.2.2 ELF_GEN_FIELD_GET_SET(hdr, e_phnum, u16)3.1.2.3 ELF_GEN_FIELD_GET_SET(hdr, e_shnum, u16)3.1.2.4 ELF_GEN_FIELD_GET_SET(hdr, e_phoff, u64)3.1.2.5 ELF_GEN_FIELD_GET_SET(hdr, e_shoff, u64)3.1.2.6 ELF_GEN_FIELD_GET_SET(hdr, e_shstrndx, u16)3.1.2.7 ELF_GEN_FIELD_GET_SET(hdr, e_shstrndx, u16)3.1.2.8 ELF_GEN_FIELD_GET_SET(hdr, e_machine, u16)3.1.2.9 ELF_GEN_FIELD_GET_SET(hdr, e_type, u16)3.1.2.10 ELF_GEN_FIELD_GET_SET(hdr, e_version, u32)3.1.2.11 ELF_GEN_FIELD_GET_SET(hdr, e_ehsize, u32)3.1.2.12 ELF_GEN_FIELD_GET_SET(hdr, e_phentsize, u16)3.1.2.13 ELF_GEN_FIELD_GET_SET(hdr, e_shentsize, u16) 3.2 elf program header3.2.1 elf program header解析接口3.2.2 elf program header各个解析函数为3.2.2.1 ELF_GEN_FIELD_GET_SET(phdr, p_paddr, u64)3.2.2.2 ELF_GEN_FIELD_GET_SET(phdr, p_vaddr, u64)3.2.2.3 ELF_GEN_FIELD_GET_SET(phdr, p_filesz, u64)3.2.2.4 ELF_GEN_FIELD_GET_SET(phdr, p_memsz, u64)3.2.2.5 ELF_GEN_FIELD_GET_SET(phdr, p_type, u32)3.2.2.6 ELF_GEN_FIELD_GET_SET(phdr, p_offset, u64)3.2.2.7 ELF_GEN_FIELD_GET_SET(phdr, p_flags, u32)3.2.2.8 ELF_GEN_FIELD_GET_SET(phdr, p_align, u64) 3.3 elf section header3.3.1 elf section header解析接口3.3.2 elf section header各个解析函数为：3.3.2.1 ELF_GEN_FIELD_GET_SET(shdr, sh_type, u32)3.3.2.2 ELF_GEN_FIELD_GET_SET(shdr, sh_flags, u32)3.3.2.3 ELF_GEN_FIELD_GET_SET(shdr, sh_entsize, u16)3.3.2.4 ELF_GEN_FIELD_GET_SET(shdr, sh_size, u64)3.3.2.5 ELF_GEN_FIELD_GET_SET(shdr, sh_offset, u64)3.3.2.6 ELF_GEN_FIELD_GET_SET(shdr, sh_name, u32)3.3.2.7 ELF_GEN_FIELD_GET_SET(shdr, sh_addr, u64)在linux中存在的remoteproc的驱动中用到了很多elf解析的函数，比如
elf_size_of_phdr， elf_phdr_get_p_paddr以及 elf_hdr_get_e_phnum等等接口。当我们直接搜对应的函数时会发现无法找到其定义，其实这些函数的实现被定义在 drivers/remoteproc/remoteproc_elf_helpers.h头文件中。
1 ELF文件组织结构
下面以ELF64为例
Start of program headers: 64 (bytes into file)Start of section headers: 220982296 (bytes into file)Size of this header: 64 (bytes)Size of program headers: 56 (bytes)Size of section headers: 64 (bytes)$ readelf -hW vmlinuxELF Header: Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 Class: ELF64 Data: 2's complement, little endian Version: 1 (current) OS/ABI: UNIX - System V ABI Version: 0 Type: DYN (Shared object file) Machine: AArch64 Version: 0x1 Entry point address: 0xffff800008000000 Start of program headers: 64 (bytes into file) Start of section headers: 220982296 (bytes into file) Flags: 0x0 Size of this header: 64 (bytes) Size of program headers: 56 (bytes) Number of program headers: 5 Size of section headers: 64 (bytes) Number of section headers: 40 Section header string table index: 39$
2 ELF_GEN_FIELD_GET_SET
ELF_GEN_FIELD_GET_SET是对应组织hdr，phdr，shdr各个头解析函数的最根本的函数。
其实现为如下所示：
ELF_GEN_FIELD_GET_SET最终会生成两个inline函数，一个为elf_##__s##_get_##__field一个为elf_##__s##_set_##__field，具体函数名字会依据ELF_GEN_FIELD_GET_SET参数的不同而不同。##表示的是字符串链接符，比如ELF_GEN_FIELD_GET_SET(hdr, e_entry, u64)，最终会被解析为elf_hdr_get_e_entry和elf_hdr_set_e_entry两个函数，两个函数的返回类型为u64。 /* Generate getter and setter for a specific elf struct/field */#define ELF_GEN_FIELD_GET_SET(__s, __field, __type) \static inline __type elf_##__s##_get_##__field(u8 class, const void *arg) \{ \ if (class == ELFCLASS32) \ return (__type) ((const struct elf32_##__s *) arg)->__field; \ else \ return (__type) ((const struct elf64_##__s *) arg)->__field; \ } \static inline void elf_##__s##_set_##__field(u8 class, void *arg, \ __type value) \{ \ if (class == ELFCLASS32) \ ((struct elf32_##__s *) arg)->__field = (__type) value; \ else \ ((struct elf64_##__s *) arg)->__field = (__type) value; \}3 elf 各种header解析接口以及其实现
3.1 elf header
elf32和elf64 header数据结构如下所示，其分别对应于下面的elf header解析函数。
#define EI_NIDENT 16typedef struct elf32_hdr{ unsigned char e_ident[EI_NIDENT]; Elf32_Half e_type; Elf32_Half e_machine; Elf32_Word e_version; Elf32_Addr e_entry; /* Entry point */ Elf32_Off e_phoff; Elf32_Off e_shoff; Elf32_Word e_flags; Elf32_Half e_ehsize; Elf32_Half e_phentsize; Elf32_Half e_phnum; Elf32_Half e_shentsize; Elf32_Half e_shnum; Elf32_Half e_shstrndx;} Elf32_Ehdr;typedef struct elf64_hdr { unsigned char e_ident[EI_NIDENT]; /* ELF "magic number" */ Elf64_Half e_type; Elf64_Half e_machine; Elf64_Word e_version; Elf64_Addr e_entry; /* Entry point virtual address */ Elf64_Off e_phoff; /* Program header table file offset */ Elf64_Off e_shoff; /* Section header table file offset */ Elf64_Word e_flags; Elf64_Half e_ehsize; Elf64_Half e_phentsize; Elf64_Half e_phnum; Elf64_Half e_shentsize; Elf64_Half e_shnum; Elf64_Half e_shstrndx;} Elf64_Ehdr;3.1.1 elf header解析接口
ELF_GEN_FIELD_GET_SET(hdr, e_entry, u64)ELF_GEN_FIELD_GET_SET(hdr, e_phnum, u16)ELF_GEN_FIELD_GET_SET(hdr, e_shnum, u16)ELF_GEN_FIELD_GET_SET(hdr, e_phoff, u64)ELF_GEN_FIELD_GET_SET(hdr, e_shoff, u64)ELF_GEN_FIELD_GET_SET(hdr, e_shstrndx, u16)ELF_GEN_FIELD_GET_SET(hdr, e_machine, u16) ELF_GEN_FIELD_GET_SET(hdr, e_type, u16)ELF_GEN_FIELD_GET_SET(hdr, e_version, u32)ELF_GEN_FIELD_GET_SET(hdr, e_ehsize, u32)ELF_GEN_FIELD_GET_SET(hdr, e_phentsize, u16)ELF_GEN_FIELD_GET_SET(hdr, e_shentsize, u16)3.1.2 elf header各个解析函数为：
3.1.2.1 ELF_GEN_FIELD_GET_SET(hdr, e_entry, u64)
static inline u64 elf_hdr_get_e_entry(u8 class, const void *arg)static inline u64 elf_hdr_set_e_entry(u8 class, void *arg, u64 value))3.1.2.2 ELF_GEN_FIELD_GET_SET(hdr, e_phnum, u16)
static inline u16 elf_hdr_get_e_phnum(u8 class, const void *arg)static inline u16 elf_hdr_set_e_phnum(u8 class, void *arg, u16 value))3.1.2.3 ELF_GEN_FIELD_GET_SET(hdr, e_shnum, u16)
static inline u16 elf_hdr_get_e_shnum(u8 class, const void *arg)static inline u16 elf_hdr_set_e_shnum(u8 class, void *arg, u16 value))3.1.2.4 ELF_GEN_FIELD_GET_SET(hdr, e_phoff, u64)
static inline u64 elf_hdr_get_e_phoff(u8 class, const void *arg)static inline u64 elf_hdr_set_e_phoff(u8 class, void *arg, u64 value))3.1.2.5 ELF_GEN_FIELD_GET_SET(hdr, e_shoff, u64)
static inline u64 elf_hdr_get_e_shoff(u8 class, const void *arg)static inline u64 elf_hdr_set_e_shoff(u8 class, void *arg, u64 value))3.1.2.6 ELF_GEN_FIELD_GET_SET(hdr, e_shstrndx, u16)
static inline u16 elf_hdr_get_e_shstrndx(u8 class, const void *arg)static inline u16 elf_hdr_set_e_shstrndx(u8 class, void *arg, u16 value))3.1.2.7 ELF_GEN_FIELD_GET_SET(hdr, e_shstrndx, u16)
static inline u16 elf_hdr_get_e_shstrndx(u8 class, const void *arg)static inline u16 elf_hdr_set_e_shstrndx(u8 class, void *arg, u16 value))3.1.2.8 ELF_GEN_FIELD_GET_SET(hdr, e_machine, u16)
static inline u16 elf_hdr_get_e_machine(u8 class, const void *arg)static inline u16 elf_hdr_set_e_machine(u8 class, void *arg, u16 value))3.1.2.9 ELF_GEN_FIELD_GET_SET(hdr, e_type, u16)
static inline u16 elf_hdr_get_e_type(u8 class, const void *arg)static inline u16 elf_hdr_set_e_type(u8 class, void *arg, u16 value))3.1.2.10 ELF_GEN_FIELD_GET_SET(hdr, e_version, u32)
static inline u32 elf_hdr_get_e_version(u8 class, const void *arg)static inline u32 elf_hdr_set_e_version(u8 class, void *arg, u32 value))3.1.2.11 ELF_GEN_FIELD_GET_SET(hdr, e_ehsize, u32)
static inline u32 elf_hdr_get_e_ehsize(u8 class, const void *arg)static inline u32 elf_hdr_set_e_ehsize(u8 class, void *arg, u32 value))3.1.2.12 ELF_GEN_FIELD_GET_SET(hdr, e_phentsize, u16)
static inline u16 elf_hdr_get_e_phentsize(u8 class, const void *arg)static inline u16 elf_hdr_set_e_phentsize(u8 class, void *arg, u16 value))3.1.2.13 ELF_GEN_FIELD_GET_SET(hdr, e_shentsize, u16)
static inline u16 elf_hdr_get_e_shentsize(u8 class, const void *arg)static inline u16 elf_hdr_set_e_shentsize(u8 class, void *arg, u16 value))3.2 elf program header
elf32和elf64 program header数据结构如下所示，其分别对应于下面的elf program header解析函数。
/* These constants define the permissions on sections in the program header, p_flags. */#define PF_R 0x4#define PF_W 0x2#define PF_X 0x1typedef struct elf32_phdr{ 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_phdr { Elf64_Word p_type; Elf64_Word p_flags; Elf64_Off p_offset; /* Segment file offset */ Elf64_Addr p_vaddr; /* Segment virtual address */ Elf64_Addr p_paddr; /* Segment physical address */ Elf64_Xword p_filesz; /* Segment size in file */ Elf64_Xword p_memsz; /* Segment size in memory */ Elf64_Xword p_align; /* Segment alignment, file & memory */} Elf64_Phdr;3.2.1 elf program header解析接口
ELF_GEN_FIELD_GET_SET(phdr, p_paddr, u64)ELF_GEN_FIELD_GET_SET(phdr, p_vaddr, u64)ELF_GEN_FIELD_GET_SET(phdr, p_filesz, u64)ELF_GEN_FIELD_GET_SET(phdr, p_memsz, u64)ELF_GEN_FIELD_GET_SET(phdr, p_type, u32)ELF_GEN_FIELD_GET_SET(phdr, p_offset, u64) ELF_GEN_FIELD_GET_SET(phdr, p_flags, u32)ELF_GEN_FIELD_GET_SET(phdr, p_align, u64)3.2.2 elf program header各个解析函数为
3.2.2.1 ELF_GEN_FIELD_GET_SET(phdr, p_paddr, u64)
static inline u64 elf_phdr_get_p_paddr(u8 class, const void *arg)static inline u64 elf_phdr_set_p_paddr(u8 class, void *arg, u64 value))3.2.2.2 ELF_GEN_FIELD_GET_SET(phdr, p_vaddr, u64)
static inline u64 elf_phdr_get_p_vaddr(u8 class, const void *arg)static inline u64 elf_phdr_set_p_vaddr(u8 class, void *arg, u64 value))3.2.2.3 ELF_GEN_FIELD_GET_SET(phdr, p_filesz, u64)
static inline u64 elf_phdr_get_p_filesz(u8 class, const void *arg)static inline u64 elf_phdr_set_p_filesz(u8 class, void *arg, u64 value))3.2.2.4 ELF_GEN_FIELD_GET_SET(phdr, p_memsz, u64)
static inline u64 elf_phdr_get_p_memsz(u8 class, const void *arg)static inline u64 elf_phdr_set_p_memsz(u8 class, void *arg, u64 value))3.2.2.5 ELF_GEN_FIELD_GET_SET(phdr, p_type, u32)
static inline u32 elf_phdr_get_p_type(u8 class, const void *arg)static inline u32 elf_phdr_set_p_type(u8 class, void *arg, u32 value))3.2.2.6 ELF_GEN_FIELD_GET_SET(phdr, p_offset, u64)
static inline u64 elf_phdr_get_p_offset(u8 class, const void *arg)static inline u64 elf_phdr_set_p_offset(u8 class, void *arg, u64 value))3.2.2.7 ELF_GEN_FIELD_GET_SET(phdr, p_flags, u32)
static inline u32 elf_phdr_get_p_flags(u8 class, const void *arg)static inline u32 elf_phdr_set_p_flags(u8 class, void *arg, u32 value))3.2.2.8 ELF_GEN_FIELD_GET_SET(phdr, p_align, u64)
static inline u64 elf_phdr_get_p_align(u8 class, const void *arg)static inline u64 elf_phdr_set_p_align(u8 class, void *arg, u64 value))3.3 elf section header
elf32和elf64 section header数据结构如下所示，其分别对应于下面的elf section header解析函数。
typedef struct elf32_shdr { 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_shdr { Elf64_Word sh_name; /* Section name, index in string tbl */ Elf64_Word sh_type; /* Type of section */ Elf64_Xword sh_flags; /* Miscellaneous section attributes */ Elf64_Addr sh_addr; /* Section virtual addr at execution */ Elf64_Off sh_offset; /* Section file offset */ Elf64_Xword sh_size; /* Size of section in bytes */ Elf64_Word sh_link; /* Index of another section */ Elf64_Word sh_info; /* Additional section information */ Elf64_Xword sh_addralign; /* Section alignment */ Elf64_Xword sh_entsize; /* Entry size if section holds table */} Elf64_Shdr;3.3.1 elf section header解析接口
ELF_GEN_FIELD_GET_SET(shdr, sh_type, u32)ELF_GEN_FIELD_GET_SET(shdr, sh_flags, u32)ELF_GEN_FIELD_GET_SET(shdr, sh_entsize, u16)ELF_GEN_FIELD_GET_SET(shdr, sh_size, u64)ELF_GEN_FIELD_GET_SET(shdr, sh_offset, u64)ELF_GEN_FIELD_GET_SET(shdr, sh_name, u32)ELF_GEN_FIELD_GET_SET(shdr, sh_addr, u64)3.3.2 elf section header各个解析函数为：
3.3.2.1 ELF_GEN_FIELD_GET_SET(shdr, sh_type, u32)
static inline u32 elf_shdr_get_sh_type(u8 class, const void *arg)static inline u32 elf_shdr_set_sh_type(u8 class, void *arg, u32 value))3.3.2.2 ELF_GEN_FIELD_GET_SET(shdr, sh_flags, u32)
static inline u32 elf_shdr_get_sh_flags(u8 class, const void *arg)static inline u32 elf_shdr_set_sh_flags(u8 class, void *arg, u32 value))3.3.2.3 ELF_GEN_FIELD_GET_SET(shdr, sh_entsize, u16)
static inline u16 elf_shdr_get_sh_entsize(u8 class, const void *arg)static inline u16 elf_shdr_set_sh_entsize(u8 class, void *arg, u16 value))3.3.2.4 ELF_GEN_FIELD_GET_SET(shdr, sh_size, u64)
static inline u64 elf_shdr_get_sh_size(u8 class, const void *arg)static inline u64 elf_shdr_set_sh_size(u8 class, void *arg, u64 value))3.3.2.5 ELF_GEN_FIELD_GET_SET(shdr, sh_offset, u64)
static inline u64 elf_shdr_get_sh_offset(u8 class, const void *arg)static inline u64 elf_shdr_set_sh_offset(u8 class, void *arg, u64 value))3.3.2.6 ELF_GEN_FIELD_GET_SET(shdr, sh_name, u32)
static inline u32 elf_shdr_get_sh_name(u8 class, const void *arg)static inline u32 elf_shdr_set_sh_name(u8 class, void *arg, u32 value))3.3.2.7 ELF_GEN_FIELD_GET_SET(shdr, sh_addr, u64)
static inline u64 elf_shdr_get_sh_addr(u8 class, const void *arg)static inline u64 elf_shdr_set_sh_addr(u8 class, void *arg, u64 value))
