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[lcrash] ADD: Dynamic linker for cckernel

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This commit is contained in:
xwashere 2024-04-23 13:30:26 -04:00
parent 1ab0e55277
commit dd850450cc
Signed by: XWasHere
GPG Key ID: 042F8BFA1B0EF93B
3 changed files with 111 additions and 2 deletions
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69
lcrash/elf/elf.h
View File

@ -17,6 +17,24 @@
#define PT_PHDR 6
#define PT_TLS 7
#define SHT_NULL 0
#define SHT_PROGBITS 1
#define SHT_SYMTAB 2
#define SHT_STRTAB 3
#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
#define SHT_INIT_ARRAY 14
#define SHT_FINI_ARRAY 15
#define SHT_PREINIT_ARRAY 16
#define SHT_GROUP 17
#define SHT_SYMTAB_SHNDX 18
struct [[gnu::packed]] Elf64_Ehdr {
c8 e_ident[16];
u16 e_type;
@ -30,7 +48,7 @@ struct [[gnu::packed]] Elf64_Ehdr {
u16 e_phentsize;
u16 e_phnum;
u16 e_shentsize;
u16 e_shentnum;
u16 e_shnum;
u16 e_shstrndx;
};
@ -45,4 +63,53 @@ struct [[gnu::packed]] Elf64_Phdr {
u64 p_align;
};
struct [[gnu::packed]] Elf64_Shdr {
u32 sh_name;
u32 sh_type;
u64 sh_flags;
u64 sh_addr;
u64 sh_offset;
u64 sh_size;
u32 sh_link;
u32 sh_info;
u64 sh_addralign;
u64 sh_entsize;
};
#define ELF64_R_SYM(info) ((info)>>32);
#define ELF64_R_TYPE(info) ((u32)info)
#define ELF64_R_AMD64_NONE 0
#define ELF64_R_AMD64_64 1
#define ELF64_R_AMD64_PC32 2
#define ELF64_R_AMD64_GOT32 3
#define ELF64_R_AMD64_PLT32 4
#define ELF64_R_AMD64_COPY 5
#define ELF64_R_AMD64_GLOB_DAT 6
#define ELF64_R_AMD64_JUMP_SLOT 7
#define ELF64_R_AMD64_RELATIVE 8
#define ELF64_R_AMD64_GOTPCREL 9
#define ELF64_R_AMD64_32 10
#define ELF64_R_AMD64_32S 11
#define ELF64_R_AMD64_16 12
#define ELF64_R_AMD64_PC16 13
#define ELF64_R_AMD64_8 14
#define ELF64_R_AMD64_PC8 15
#define ELF64_R_AMD64_PC64 24
#define ELF64_R_AMD64_GOTOFF64 25
#define ELF64_R_AMD64_GOTPC32 26
#define ELF64_R_AMD64_SIZE32 32
#define ELF64_R_AMD64_SIZE64 33
struct [[gnu::packed]] Elf64_Rela {
u64 r_offset;
u64 r_info;
s64 r_addend;
};
struct [[gnu::packed]] Elf64_Sym {
u32 st_name;
u8 st_info;
u8 st_other;
u16 st_shndx;
u64 st_value;
u64 st_size;
};

11
lcrash/lcrash.ld
View File

@ -5,6 +5,15 @@ ENTRY(entry64)
SECTIONS {
. = 0;
.dynsym : { *(.dynsym); }
.rela.dyn : {
*(.rela.text);
*(.rela.rodata);
*(.rela.data .rela.data.*);
*(.rela.bss);
}
.text : {
_text = .;
*(.text);
@ -19,7 +28,7 @@ SECTIONS {
.data : {
_data = .;
*(.data);
*(.data .data.*);
_edata = .;
}

33
lcrash/setup/compressed/elf.c
View File

@ -33,6 +33,39 @@ void ElfExecute(void* Binary, void* LoadAddr, struct boot_params* BootParams) {
ProgramHeaders += ElfHeader->e_phentsize;
}
// Dynamically link ourself
void* SectionHeaders = Binary + ElfHeader->e_shoff;
for (int i = 0; i < ElfHeader->e_shnum; i++) {
struct Elf64_Shdr* SectionHeader = (struct Elf64_Shdr*)SectionHeaders;
// Find RELA segments
if (SectionHeader->sh_type == SHT_RELA) {
struct Elf64_Shdr* SymbolTable = (struct Elf64_Shdr*)(Binary + ElfHeader->e_shoff + ElfHeader->e_shentsize * SectionHeader->sh_link);
void* RelocTab = Binary + SectionHeader->sh_offset;
void* SymblTab = Binary + SymbolTable->sh_offset;
for (int RelocOffset = 0; RelocOffset < SectionHeader->sh_size; RelocOffset += SectionHeader->sh_entsize) {
struct Elf64_Rela* Reloc = RelocTab + RelocOffset;
[[maybe_unused]] struct Elf64_Sym* Symbol = SymblTab + SymbolTable->sh_entsize * ELF64_R_SYM(Reloc->r_info);
void* Target = LoadAddr + Reloc->r_offset;
switch (ELF64_R_TYPE(Reloc->r_info)) {
case ELF64_R_AMD64_RELATIVE: {
*((u64*)Target) = (u64)(LoadAddr + Reloc->r_addend);
break;
}
default: {
while (1) {}
}
}
}
}
SectionHeaders += ElfHeader->e_shentsize;
}
// Collect entry point
[[noreturn]] void fake_dont_call(struct boot_params*); // stupid hack
typeof(fake_dont_call)* KernelEntry = LoadAddr + ElfHeader->e_entry;