Skip to content

Commit

Permalink
refactor
Browse files Browse the repository at this point in the history
  • Loading branch information
@v420v
v420v committed Jul 5, 2023
1 parent 57fa69d commit 877123e
Show file tree
Hide file tree
Showing 11 changed files with 18,106 additions and 19,644 deletions.
196 changes: 155 additions & 41 deletions elf/elf.v
View file
Original file line number Diff line number Diff line change
@@ -1,7 +1,6 @@
module elf

import encoder
import header
import os

pub struct Elf {
Expand All @@ -11,21 +10,136 @@ pub struct Elf {
user_defined_sections map[string]&encoder.UserDefinedSection
mut:
keep_locals bool // flag to keep local labels. labels that start from `.L`
ehdr header.Elf64_Ehdr // Elf header
ehdr Elf64_Ehdr // Elf header
symtab_symbol_indexs map[string]int // symtab symbol index
local_symbols_count int // used in .symtab section header
rela_symbols []string // symbols that are not defined
user_defined_section_names []string // list of user-defined section names
user_defined_section_idx map[string]int // user-defined sections index
section_name_offs map[string]int
strtab []u8
symtab []header.Elf64_Sym
symtab []Elf64_Sym
rela_section_names []string
rela map[string][]header.Elf64_Rela
rela map[string][]Elf64_Rela
shstrtab []u8
section_headers []header.Elf64_Shdr
section_headers []Elf64_Shdr
}

pub struct Elf64_Ehdr {
e_ident [16]u8
e_type u16
e_machine u16
e_version u32
e_entry voidptr
e_phoff voidptr
e_shoff voidptr
e_flags u32
e_ehsize u16
e_phentsize u16
e_phnum u16
e_shentsize u16
e_shnum u16
e_shstrndx u16
}

pub struct Elf64_Sym {
st_name u32
st_info u8
st_other u8
st_shndx u16
st_value voidptr
st_size u64
}

pub struct Elf64_Shdr {
sh_name u32
sh_type u32
sh_flags voidptr
sh_addr voidptr
sh_offset voidptr
sh_size voidptr
sh_link u32
sh_info u32
sh_addralign voidptr
sh_entsize voidptr
}

pub struct Elf64_Rela {
r_offset u64
r_info u64
r_addend i64
}

pub struct Elf64_Phdr {
ph_type u32
ph_flags u32
ph_off u64
ph_vaddr u64
ph_paddr u64
ph_filesz u64
ph_memsz u64
ph_align u64
}

const (
stb_local = 0
stb_global = 1
//-------------------------------
stt_notype = 0
stt_object = 1
stt_func = 2
stt_section = 3
stt_file = 4
stt_common = 5
stt_tls = 6
stt_relc = 8
stt_srelc = 9
stt_loos = 10
stt_hios = 12
stt_loproc = 13
stt_hiproc = 14
//-------------------------------
sht_null = 0
sht_progbits = 1
sht_symtab = 2
sht_strtab = 3
sht_rela = 4
//-------------------------------
shf_write = 0x1
shf_alloc = 0x2
shf_execinstr = 0x4
shf_merge = 0x10
shf_strings = 0x20
shf_info_link = 0x40
shf_link_order = 0x80
shf_os_nonconforming = 0x100
shf_group = 0x200
shf_tls = 0x400
//-------------------------------
r_x86_64_none = u64(0)
r_x86_64_64 = u64(1)
r_x86_64_pc32 = u64(2)
r_x86_64_got32 = u64(3)
r_x86_64_plt32 = u64(4)
r_x86_64_copy = u64(5)
r_x86_64_glob_dat = u64(6)
r_x86_64_jump_slot = u64(7)
r_x86_64_relative = u64(8)
r_x86_64_gotpcrel = u64(9)
r_x86_64_32 = u64(10)
r_x86_64_32s = u64(11)
r_x86_64_16 = u64(12)
r_x86_64_pc16 = u64(13)
r_x86_64_8 = u64(14)
r_x86_64_pc8 = u64(15)
r_x86_64_pc64 = u64(24)
//-------------------------------
stv_default = 0
stv_internal = 1
stv_hidden = 2
stv_protected = 3
)

pub fn new(out_file string, keep_locals bool, rela_text_users []encoder.Rela, user_defined_sections map[string]&encoder.UserDefinedSection, user_defined_symbols map[string]&encoder.Instr) &Elf {
mut e := &Elf{
out_file: out_file
Expand Down Expand Up @@ -60,8 +174,8 @@ fn (mut e Elf) elf_symbol(symbol_binding int, mut off &int, mut str &string) {
continue
}

if symbol.binding == header.stb_local {
if !e.keep_locals && symbol.binding == header.stb_local && name.to_upper().starts_with('.L') {
if symbol.binding == stb_local {
if !e.keep_locals && symbol.binding == stb_local && name.to_upper().starts_with('.L') {
continue
}
e.local_symbols_count++
Expand All @@ -73,13 +187,13 @@ fn (mut e Elf) elf_symbol(symbol_binding int, mut off &int, mut str &string) {
st_shndx := u16(e.user_defined_section_idx[symbol.section])
mut st_name := u32(0)

if symbol.symbol_type == header.stt_section {
if symbol.symbol_type == stt_section {
st_name = 0
} else {
st_name = u32(*off)
}

e.symtab << header.Elf64_Sym{
e.symtab << Elf64_Sym{
st_name: st_name
st_info: u8((symbol.binding << 4) + (symbol.symbol_type & 0xf))
st_other: symbol.visibility
Expand All @@ -100,9 +214,9 @@ fn (mut e Elf) elf_rela_symbol(mut off &int, mut str &string) {
unsafe {*off += str.len + 1}
e.symtab_symbol_indexs[symbol_name] = e.symtab_symbol_indexs.len

e.symtab << header.Elf64_Sym{
e.symtab << Elf64_Sym{
st_name: u32(*off)
st_info: u8((header.stb_global << 4) + (header.stt_notype & 0xf))
st_info: u8((stb_global << 4) + (stt_notype & 0xf))
st_shndx: 0
}
e.strtab << symbol_name.bytes()
Expand All @@ -120,9 +234,9 @@ pub fn (mut e Elf) rela_text_users() {
for r in e.rela_text_users {
mut index := 0

mut r_addend := if r.rtype in [header.r_x86_64_32s, header.r_x86_64_32, header.r_x86_64_64, header.r_x86_64_32, header.r_x86_64_16, header.r_x86_64_8] {
mut r_addend := if r.rtype in [r_x86_64_32s, r_x86_64_32, r_x86_64_64, r_x86_64_32, r_x86_64_16, r_x86_64_8] {
i64(0)
} else if r.rtype in [header.r_x86_64_pc32] {
} else if r.rtype in [r_x86_64_pc32] {
i64(r.offset - r.instr.code.len)
} else {
i64(0-4)
Expand All @@ -134,7 +248,7 @@ pub fn (mut e Elf) rela_text_users() {
}

if s := e.user_defined_symbols[r.uses] {
if s.binding == header.stb_global {
if s.binding == stb_global {
index = e.symtab_symbol_indexs[r.uses]
} else {
r_addend += s.addr
Expand All @@ -145,7 +259,7 @@ pub fn (mut e Elf) rela_text_users() {
}

rela_section_name := '.rela' + r.instr.section
e.rela[rela_section_name] << header.Elf64_Rela{
e.rela[rela_section_name] << Elf64_Rela{
r_offset: u64(r.instr.addr + r.offset),
r_info: (u64(index) << 32) + r.rtype,
r_addend: r_addend + r.adjust,
Expand All @@ -171,19 +285,19 @@ pub fn (mut e Elf) collect_rela_symbols() {
pub fn (mut e Elf) build_symtab_strtab() {
// null
e.strtab << [u8(0x00)]
e.symtab << header.Elf64_Sym{
e.symtab << Elf64_Sym{
st_name: 0
st_info: u8((header.stb_local << 4) + (header.stt_notype & 0xf))
st_info: u8((stb_local << 4) + (stt_notype & 0xf))
}
e.symtab_symbol_indexs[''] = e.symtab_symbol_indexs.len // null symbol
e.local_symbols_count++

mut off := 0
mut str := ''

e.elf_symbol(header.stb_local, mut &off, mut &str) // local
e.elf_symbol(stb_local, mut &off, mut &str) // local
e.elf_rela_symbol(mut &off, mut &str) // rela local
e.elf_symbol(header.stb_global, mut &off, mut &str) // global
e.elf_symbol(stb_global, mut &off, mut &str) // global

add_padding(mut e.strtab)
}
Expand Down Expand Up @@ -224,23 +338,23 @@ pub fn (mut e Elf) build_shstrtab() {

// TODO: refactor later...
pub fn (mut e Elf) build_headers() {
mut section_offs := sizeof(header.Elf64_Ehdr)
mut section_offs := sizeof(Elf64_Ehdr)
mut section_idx := {'': 0}

// null section
e.section_headers << header.Elf64_Shdr{
e.section_headers << Elf64_Shdr{
sh_name: u32(e.section_name_offs[''])
sh_type: header.sht_null
sh_type: sht_null
}

// user-defined sections
for name in e.user_defined_section_names {
section := e.user_defined_sections[name] or {
panic('[internal error] unkown section `$name`')
}
e.section_headers << header.Elf64_Shdr{
e.section_headers << Elf64_Shdr{
sh_name: u32(e.section_name_offs[name])
sh_type: header.sht_progbits
sh_type: sht_progbits
sh_flags: section.flags
sh_addr: 0
sh_offset: section_offs
Expand All @@ -259,14 +373,14 @@ pub fn (mut e Elf) build_headers() {
section_idx['.strtab'] = section_idx.len

symtab_ofs := strtab_ofs + strtab_size
symtab_size := sizeof(header.Elf64_Sym) * u32(e.symtab.len)
symtab_size := sizeof(Elf64_Sym) * u32(e.symtab.len)
section_idx['.symtab'] = section_idx.len

e.section_headers << [
// .strtab
header.Elf64_Shdr{
Elf64_Shdr{
sh_name: u32(e.section_name_offs['.strtab'])
sh_type: header.sht_strtab
sh_type: sht_strtab
sh_flags: 0
sh_addr: 0
sh_offset: strtab_ofs
Expand All @@ -277,44 +391,44 @@ pub fn (mut e Elf) build_headers() {
sh_entsize: 0
},
// .symtab
header.Elf64_Shdr{
Elf64_Shdr{
sh_name: u32(e.section_name_offs['.symtab'])
sh_type: header.sht_symtab
sh_type: sht_symtab
sh_flags: 0
sh_addr: 0
sh_offset: symtab_ofs
sh_size: symtab_size
sh_link: u32(section_idx['.strtab']) // section number of .strtab
sh_info: u32(e.local_symbols_count) // Number of local symbols
sh_addralign: 8
sh_entsize: sizeof(header.Elf64_Sym)
sh_entsize: sizeof(Elf64_Sym)
}
]

section_offs = symtab_ofs + symtab_size

// add rela ... to section headers
for name in e.rela_section_names {
size := u32(e.rela[name].len) * sizeof(header.Elf64_Rela)
e.section_headers << header.Elf64_Shdr{
size := u32(e.rela[name].len) * sizeof(Elf64_Rela)
e.section_headers << Elf64_Shdr{
sh_name: u32(e.section_name_offs[name])
sh_type: header.sht_rela,
sh_flags: header.shf_info_link
sh_type: sht_rela,
sh_flags: shf_info_link
sh_addr: 0
sh_offset: section_offs
sh_size: size
sh_link: u32(section_idx['.symtab'])
sh_info: u32(section_idx[name[5..]]) // target section index. if `.rela.text` the target will be `.text`
sh_addralign: 8
sh_entsize: sizeof(header.Elf64_Rela)
sh_entsize: sizeof(Elf64_Rela)
}
section_offs += size
}

// .shstrtab
e.section_headers << header.Elf64_Shdr{
e.section_headers << Elf64_Shdr{
sh_name: u32(e.section_name_offs['.shstrtab'])
sh_type: header.sht_strtab
sh_type: sht_strtab
sh_flags: 0
sh_addr: 0
sh_offset: section_offs
Expand All @@ -328,7 +442,7 @@ pub fn (mut e Elf) build_headers() {
sectionheader_ofs := section_offs + u32(e.shstrtab.len)

// elf header
e.ehdr = header.Elf64_Ehdr{
e.ehdr = Elf64_Ehdr{
e_ident: [
u8(0x7f), 0x45, 0x4c, 0x46, // Magic number ' ELF' in ascii format
0x02, // 2 = 64-bit
Expand All @@ -342,10 +456,10 @@ pub fn (mut e Elf) build_headers() {
e_phoff: 0
e_shoff: sectionheader_ofs
e_flags: 0x0
e_ehsize: u16(sizeof(header.Elf64_Ehdr))
e_phentsize: u16(sizeof(header.Elf64_Phdr))
e_ehsize: u16(sizeof(Elf64_Ehdr))
e_phentsize: u16(sizeof(Elf64_Phdr))
e_phnum: 0
e_shentsize: u16(sizeof(header.Elf64_Shdr))
e_shentsize: u16(sizeof(Elf64_Shdr))
e_shnum: u16(e.section_headers.len)
e_shstrndx: u16(e.section_headers.len - 1)
}
Expand Down
Loading

0 comments on commit 877123e

Please sign in to comment.