int apply_relocate_add()

in kernel/module.c [24:88]

• 60 lines of code
• 9 McCabe index (conditional complexity)

int apply_relocate_add(Elf32_Shdr *sechdrs,
		   const char *strtab,
		   unsigned int symindex,
		   unsigned int relsec,
		   struct module *me)
{
	unsigned int i;
	Elf32_Rela *rel = (void *)sechdrs[relsec].sh_addr;
	Elf32_Sym *sym;
	Elf32_Addr relocation;
	uint32_t *location;
	uint32_t value;

	pr_debug("Applying relocate section %u to %u\n", relsec,
		 sechdrs[relsec].sh_info);
	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
		/* This is where to make the change */
		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
			+ rel[i].r_offset;
		/* This is the symbol it is referring to.  Note that all
		   undefined symbols have been resolved.  */
		sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
			+ ELF32_R_SYM(rel[i].r_info);
		relocation = sym->st_value + rel[i].r_addend;

		switch (ELF32_R_TYPE(rel[i].r_info)) {
		case R_SH_NONE:
			break;
		case R_SH_DIR32:
			value = get_unaligned(location);
			value += relocation;
			put_unaligned(value, location);
			break;
		case R_SH_REL32:
			relocation = (relocation - (Elf32_Addr) location);
			value = get_unaligned(location);
			value += relocation;
			put_unaligned(value, location);
			break;
		case R_SH_IMM_LOW16:
			*location = (*location & ~0x3fffc00) |
				((relocation & 0xffff) << 10);
			break;
		case R_SH_IMM_MEDLOW16:
			*location = (*location & ~0x3fffc00) |
				(((relocation >> 16) & 0xffff) << 10);
			break;
		case R_SH_IMM_LOW16_PCREL:
			relocation -= (Elf32_Addr) location;
			*location = (*location & ~0x3fffc00) |
				((relocation & 0xffff) << 10);
			break;
		case R_SH_IMM_MEDLOW16_PCREL:
			relocation -= (Elf32_Addr) location;
			*location = (*location & ~0x3fffc00) |
				(((relocation >> 16) & 0xffff) << 10);
			break;
		default:
			printk(KERN_ERR "module %s: Unknown relocation: %u\n",
			       me->name, ELF32_R_TYPE(rel[i].r_info));
			return -ENOEXEC;
		}
	}
	return 0;
}