// SPDX-License-Identifier: GPL-2.0 #include <linux/moduleloader.h> #include <linux/elf.h> #include <linux/vmalloc.h> #include <linux/fs.h> #include <linux/string.h> #include <linux/kernel.h> int apply_relocate_add(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex, unsigned int relsec, struct module *me) { unsigned int i; Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr; pr_debug("Applying relocate section %u to %u\n", relsec, sechdrs[relsec].sh_info); for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) { /* This is where to make the change */ uint32_t *loc = (uint32_t *)(sechdrs[sechdrs[relsec].sh_info].sh_addr + rela[i].r_offset); /* This is the symbol it is referring to. Note that all undefined symbols have been resolved. */ Elf32_Sym *sym = (Elf32_Sym *)sechdrs[symindex].sh_addr + ELF32_R_SYM(rela[i].r_info); uint32_t v = sym->st_value + rela[i].r_addend; switch (ELF32_R_TYPE(rela[i].r_info)) { case R_H8_DIR24R8: loc = (uint32_t *)((uint32_t)loc - 1); *loc = (*loc & 0xff000000) | ((*loc & 0xffffff) + v); break; case R_H8_DIR24A8: if (ELF32_R_SYM(rela[i].r_info)) *loc += v; break; case R_H8_DIR32: case R_H8_DIR32A16: *loc += v; break; case R_H8_PCREL16: v -= (unsigned long)loc + 2; if ((Elf32_Sword)v > 0x7fff || (Elf32_Sword)v < -(Elf32_Sword)0x8000) goto overflow; else *(unsigned short *)loc = v; break; case R_H8_PCREL8: v -= (unsigned long)loc + 1; if ((Elf32_Sword)v > 0x7f || (Elf32_Sword)v < -(Elf32_Sword)0x80) goto overflow; else *(unsigned char *)loc = v; break; default: pr_err("module %s: Unknown relocation: %u\n", me->name, ELF32_R_TYPE(rela[i].r_info)); return -ENOEXEC; } } return 0; overflow: pr_err("module %s: relocation offset overflow: %08x\n", me->name, rela[i].r_offset); return -ENOEXEC; }