What is the symbol table in ELF?
See sys/elf. H. An index into the object file’s symbol string table, which contains the character representations of the symbol names. If the value is nonzero, the value represents a string table index that provides the name of the symbol.
Table of Contents
What is NDX at Readelf?
Ndx = The section number in which the symbol is found. ABS means absolute: not set to any section address relocation.
What is a dynamic symbol table?
The dynamic linker (also known as the runtime loader or RTLD) uses the dynsym table at program load time to determine which DLLs to assign to the address space of the program being loaded into memory.
What is the symbol table in Linux?
On Linux, the system. The map file is a symbol table used by the kernel. A symbol table is a lookup between symbol names and their addresses in memory. A symbol name can be the name of a variable or the name of a function. It is especially useful for debugging kernel panic and kernel oops.
Where is the symbol table in ELF?
You can find where a symbol is placed in an executable ELF image. To find where a symbol is placed in an ELF image file, use the –text -s -v options to view the symbol table and detailed information about each segment and section header, for example: The symbol table identifies the section where the symbol is located. stuck.
What is Dynsym?
The dynsym is a smaller version of the symtab that only contains global symbols. Therefore, the information found in dynsym is also found in symtab, while the reverse is not necessarily true. You are probably wondering why we complicate the world with two symbol tables.
What is ElfLinux?
ELF is short for Executable and Linkable Format and defines the structure of core binaries, libraries, and files. The formal specification allows the operating system to correctly interpret its underlying machine instructions.
What is littab?
Literal table) LITTAB): – The literal table contains all literals and the address of all literals. For literals. The LTORG directives place all constants in consecutive memory locations. If we don’t use LTORG, all literals are placed after END in memory.
What does Vmlinuz mean?
vmlinuz: vmlinuz is the name of the Linux kernel executable. vmlinuz is a compressed Linux kernel and loads the operating system into memory to make the server usable. vmlinuz = LINUx virtual memory gZip = Compressed bootable Linux kernel executable.
What is the use of ELF file?
In computing, the Executable and Linkable Format (ELF, formerly called Extensible Linkage Format) is a common standard file format for executable files, object code, shared libraries, and core dumps.
What are the meanings of the symbols in Elf?
Type = symbol type: Func = Function, Object, File (source file name), Section = memory section, Notype = untyped or undefined absolute symbol Bind = GLOBAL binding means the symbol is visible outside the file. The LOCAL link is only visible in the file.
What does St_info mean in ELF format?
For the symbol highlighted here, we can see the following: st_size is set to 0, which means that it won’t take up any space in the binary during execution and probably won’t define a variable. st_info is set to 0x03, which means that the symbol type is SECTION, which means that it is a symbol associated with a section.
What are the meanings of the columns in the symbol table that readelf displays?
Vis = Symbols can be default, protected, hidden, or internal. Understanding ELF using readelf and objdump. I think the Ndx field shows the section number where that symbol is defined. Do a readelf -ay and find out which section the address for a given symbol corresponds to.
Where to find the relocations in ELF format?
Suffice it to say that the “relocations” will be found in the relocation tables and the symbols they refer to will be found in the ELF symbol tables. I should mention that there is also more than one symbol table and more than one relocation table, nothing more. that efficiency and extended capability in symbol resolution configuration.