/* Kernel module help for x86. Copyright (C) 2001 Rusty Russell. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #if 0 #define DEBUGP(fmt, ...) \ printk(KERN_DEBUG fmt, ##__VA_ARGS__) #else #define DEBUGP(fmt, ...) \ do { \ if (0) \ printk(KERN_DEBUG fmt, ##__VA_ARGS__); \ } while (0) #endif #ifdef CONFIG_RANDOMIZE_BASE static unsigned long module_load_offset; static int randomize_modules = 1; static int __init parse_nokaslr(char *p) { randomize_modules = 0; return 0; } early_param("nokaslr", parse_nokaslr); static unsigned long int get_module_load_offset(void) { if (randomize_modules) { mutex_lock(&module_mutex); /* * Calculate the module_load_offset the first time this * code is called. Once calculated it stays the same until * reboot. */ if (module_load_offset == 0) module_load_offset = (get_random_int() % 1024 + 1) * PAGE_SIZE; mutex_unlock(&module_mutex); } return module_load_offset; } #else static unsigned long int get_module_load_offset(void) { return 0; } #endif void *module_alloc(unsigned long size) { if (PAGE_ALIGN(size) > MODULES_LEN) return NULL; return __vmalloc_node_range(size, 1, MODULES_VADDR + get_module_load_offset(), MODULES_END, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC, NUMA_NO_NODE, __builtin_return_address(0)); } #ifdef CONFIG_X86_32 int apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex, unsigned int relsec, struct module *me) { unsigned int i; Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr; Elf32_Sym *sym; uint32_t *location; DEBUGP("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); switch (ELF32_R_TYPE(rel[i].r_info)) { case R_386_32: /* We add the value into the location given */ *location += sym->st_value; break; case R_386_PC32: /* Add the value, subtract its position */ *location += sym->st_value - (uint32_t)location; break; default: pr_err("%s: Unknown relocation: %u\n", me->name, ELF32_R_TYPE(rel[i].r_info)); return -ENOEXEC; } } return 0; } #else /*X86_64*/ int apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex, unsigned int relsec, struct module *me) { unsigned int i; Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr; Elf64_Sym *sym; void *loc; u64 val; DEBUGP("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 */ loc = (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 = (Elf64_Sym *)sechdrs[symindex].sh_addr + ELF64_R_SYM(rel[i].r_info); DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n", (int)ELF64_R_TYPE(rel[i].r_info), sym->st_value, rel[i].r_addend, (u64)loc); val = sym->st_value + rel[i].r_addend; switch (ELF64_R_TYPE(rel[i].r_info)) { case R_X86_64_NONE: break; case R_X86_64_64: *(u64 *)loc = val; break; case R_X86_64_32: *(u32 *)loc = val; if (val != *(u32 *)loc) goto overflow; break; case R_X86_64_32S: *(s32 *)loc = val; if ((s64)val != *(s32 *)loc) goto overflow; break; case R_X86_64_PC32: val -= (u64)loc; *(u32 *)loc = val; #if 0 if ((s64)val != *(s32 *)loc) goto overflow; #endif break; default: pr_err("%s: Unknown rela relocation: %llu\n", me->name, ELF64_R_TYPE(rel[i].r_info)); return -ENOEXEC; } } return 0; overflow: pr_err("overflow in relocation type %d val %Lx\n", (int)ELF64_R_TYPE(rel[i].r_info), val); pr_err("`%s' likely not compiled with -mcmodel=kernel\n", me->name); return -ENOEXEC; } #endif int module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, struct module *me) { const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL, *para = NULL; char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) { if (!strcmp(".text", secstrings + s->sh_name)) text = s; if (!strcmp(".altinstructions", secstrings + s->sh_name)) alt = s; if (!strcmp(".smp_locks", secstrings + s->sh_name)) locks = s; if (!strcmp(".parainstructions", secstrings + s->sh_name)) para = s; } if (alt) { /* patch .altinstructions */ void *aseg = (void *)alt->sh_addr; apply_alternatives(aseg, aseg + alt->sh_size); } if (locks && text) { void *lseg = (void *)locks->sh_addr; void *tseg = (void *)text->sh_addr; alternatives_smp_module_add(me, me->name, lseg, lseg + locks->sh_size, tseg, tseg + text->sh_size); } if (para) { void *pseg = (void *)para->sh_addr; apply_paravirt(pseg, pseg + para->sh_size); } /* make jump label nops */ jump_label_apply_nops(me); return 0; } void module_arch_cleanup(struct module *mod) { alternatives_smp_module_del(mod); }