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bool module_resolve_symbols(module_t *mod,Elf32_Ehdr *e) {
	unsigned i;
	Elf32_Shdr *s;
	Elf32_Sym *sym;
	const char *str;
	Elf32_Word size,entsize;
	for (i = 0, s = (Elf32_Shdr *)((char *)e + e->e_shoff); i < e->e_shnum;
		i++,s = (Elf32_Shdr *)((char *)s + e->e_shentsize)) {
		if (s->sh_type == SHT_SYMTAB) break;
	}
	if (i == e->e_shnum) {
		printf("%s: failed to find symbol table in module!\n");
		return false;
	}
	mod->symtab = (Elf32_Sym *)((char *)e + s->sh_offset);
	sym = mod->symtab;
	size = s->sh_size;
	entsize = s->sh_entsize;
	s = (Elf32_Shdr *)((char *)e + e->e_shoff + e->e_shentsize * s->sh_link);
	str = (char *)e+ s->sh_offset;
	for (i = 0; i < size/entsize; i++,sym = (Elf32_Sym *)((char *)sym + entsize)) {
		uint8_t type = ELF32_ST_TYPE(sym->st_info);
		uint8_t bind = ELF32_ST_BIND(sym->st_info);
		const char *name = str + sym->st_name;
		switch (type) {
			case STT_NOTYPE:
			case STT_OBJECT:
			if (sym->st_name != 0 && sym->st_shndx == 0) {
				sym->st_value = (Elf32_Addr)symbols_findValue(name);
				printf("Symbol %s founded in kernel: %x\n",name,sym->st_value);
				if (!sym->st_value) {
					printf("Cannot find symbol %s in kernel, abort\n",name);
					return false;
				}
			} else {
				sym->st_value += (Elf32_Addr) module_get_section_addr(mod,sym->st_shndx);
				if (bind != STB_LOCAL) {
					printf("TODO: add this to global symbol table: %s\n",name);
				}
			} break;
			case STT_FUNC:
			sym->st_value += (Elf32_Addr) module_get_section_addr(mod,sym->st_shndx);
			if (bind != STB_LOCAL) {
				printf("TODO: This function %s also need to be added to global symbols table\n",name);
			}
			if (strcmp(name,"module_main")) {
				printf("Module init found\n");
				mod->init = (void (*)(module_t *))sym->st_value;
			}
			break;
			case STT_SECTION:
			sym->st_value += (Elf32_Addr) module_get_section_addr(mod,sym->st_shndx);
			break;
			case STT_FILE:
			sym->st_value = 0;
			break;
			default:
			printf("Unknown symbol type: %d,%s\n",type,name);
			return false;
			break;
		}
	}
	return true;
}

Code: Select all

bool arch_relocSymbols(module_t *mod,void *ehdr) {
	Elf32_Ehdr *e = (Elf32_Ehdr *)ehdr;
	Elf32_Shdr *s;
	Elf32_Word entsize;
	unsigned i;
	// Find symbol table
	for (i = 0,s = (Elf32_Shdr *)((char *) e + e->e_shoff); i < e->e_shnum;
		i++,s = (Elf32_Shdr *)((char *) s + e->e_shentsize)) {
		if (s->sh_type == SHT_SYMTAB) {
			break;
		}
	}
	if (i == e->e_shnum) {
		printf("relloc: no symbol table to relocate!\n");
		return false;
	}
	entsize = s->sh_entsize;
	for (i = 0,s = (Elf32_Shdr *)((char *)e + e->e_shoff); i < e->e_shnum;
		i++,s = (Elf32_Shdr *)((char *)s + e->e_shentsize)) {
			if (s->sh_type == SHT_REL) {
				printf("Relocation segment\n");
				module_segment_t *seg;
				for (seg = mod->seg; seg; seg = seg->next) {
					if (seg->section == s->sh_info) break;
				}
				if (seg) {
					Elf32_Rel *rel,*max;
					for (rel = (Elf32_Rel *)((char *) e + s->sh_offset),
						max = rel + s->sh_size / s->sh_entsize;
						rel < max;
						rel++) {
						Elf32_Word *addr;
						Elf32_Sym *sym;
						if (seg->size < rel->r_offset) {
							printf("Relloc offset is out of segment\n");
							return false;
						}
						addr = (Elf32_Word *)((char *)seg->addr + rel->r_offset);
						sym = (Elf32_Sym *)((char *)mod->symtab + entsize * ELF32_R_SYM(rel->r_info));
						switch (ELF32_R_TYPE(rel->r_info)) {
							case R_386_32:
								*addr += sym->st_value;
								break;
							case R_386_PC32:
								*addr += (sym->st_value - (Elf32_Word)seg->addr - rel->r_offset);
								break;
						}
					}
				}
			}
	}
	return true;
}