[lcrash] ADD: Dynamic linker for cckernel

lcrash/elf/elf.h

@@ -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;
+};

lcrash/lcrash.ld

@@ -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 = .;
 	}
 

lcrash/setup/compressed/elf.c

@@ -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;