1 /* Kernel module help for x86. 2 Copyright (C) 2001 Rusty Russell. 3 4 This program is free software; you can redistribute it and/or modify 5 it under the terms of the GNU General Public License as published by 6 the Free Software Foundation; either version 2 of the License, or 7 (at your option) any later version. 8 9 This program is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU General Public License for more details. 13 14 You should have received a copy of the GNU General Public License 15 along with this program; if not, write to the Free Software 16 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 17 */ 18 19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 20 21 #include <linux/moduleloader.h> 22 #include <linux/elf.h> 23 #include <linux/vmalloc.h> 24 #include <linux/fs.h> 25 #include <linux/string.h> 26 #include <linux/kernel.h> 27 #include <linux/kasan.h> 28 #include <linux/bug.h> 29 #include <linux/mm.h> 30 #include <linux/gfp.h> 31 #include <linux/jump_label.h> 32 #include <linux/random.h> 33 34 #include <asm/text-patching.h> 35 #include <asm/page.h> 36 #include <asm/pgtable.h> 37 #include <asm/setup.h> 38 #include <asm/unwind.h> 39 40 #if 0 41 #define DEBUGP(fmt, ...) \ 42 printk(KERN_DEBUG fmt, ##__VA_ARGS__) 43 #else 44 #define DEBUGP(fmt, ...) \ 45 do { \ 46 if (0) \ 47 printk(KERN_DEBUG fmt, ##__VA_ARGS__); \ 48 } while (0) 49 #endif 50 51 #ifdef CONFIG_RANDOMIZE_BASE 52 static unsigned long module_load_offset; 53 54 /* Mutex protects the module_load_offset. */ 55 static DEFINE_MUTEX(module_kaslr_mutex); 56 57 static unsigned long int get_module_load_offset(void) 58 { 59 if (kaslr_enabled()) { 60 mutex_lock(&module_kaslr_mutex); 61 /* 62 * Calculate the module_load_offset the first time this 63 * code is called. Once calculated it stays the same until 64 * reboot. 65 */ 66 if (module_load_offset == 0) 67 module_load_offset = 68 (get_random_int() % 1024 + 1) * PAGE_SIZE; 69 mutex_unlock(&module_kaslr_mutex); 70 } 71 return module_load_offset; 72 } 73 #else 74 static unsigned long int get_module_load_offset(void) 75 { 76 return 0; 77 } 78 #endif 79 80 void *module_alloc(unsigned long size) 81 { 82 void *p; 83 84 if (PAGE_ALIGN(size) > MODULES_LEN) 85 return NULL; 86 87 p = __vmalloc_node_range(size, MODULE_ALIGN, 88 MODULES_VADDR + get_module_load_offset(), 89 MODULES_END, GFP_KERNEL, 90 PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE, 91 __builtin_return_address(0)); 92 if (p && (kasan_module_alloc(p, size) < 0)) { 93 vfree(p); 94 return NULL; 95 } 96 97 return p; 98 } 99 100 #ifdef CONFIG_X86_32 101 int apply_relocate(Elf32_Shdr *sechdrs, 102 const char *strtab, 103 unsigned int symindex, 104 unsigned int relsec, 105 struct module *me) 106 { 107 unsigned int i; 108 Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr; 109 Elf32_Sym *sym; 110 uint32_t *location; 111 112 DEBUGP("Applying relocate section %u to %u\n", 113 relsec, sechdrs[relsec].sh_info); 114 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { 115 /* This is where to make the change */ 116 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 117 + rel[i].r_offset; 118 /* This is the symbol it is referring to. Note that all 119 undefined symbols have been resolved. */ 120 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr 121 + ELF32_R_SYM(rel[i].r_info); 122 123 switch (ELF32_R_TYPE(rel[i].r_info)) { 124 case R_386_32: 125 /* We add the value into the location given */ 126 *location += sym->st_value; 127 break; 128 case R_386_PC32: 129 /* Add the value, subtract its position */ 130 *location += sym->st_value - (uint32_t)location; 131 break; 132 default: 133 pr_err("%s: Unknown relocation: %u\n", 134 me->name, ELF32_R_TYPE(rel[i].r_info)); 135 return -ENOEXEC; 136 } 137 } 138 return 0; 139 } 140 #else /*X86_64*/ 141 int apply_relocate_add(Elf64_Shdr *sechdrs, 142 const char *strtab, 143 unsigned int symindex, 144 unsigned int relsec, 145 struct module *me) 146 { 147 unsigned int i; 148 Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr; 149 Elf64_Sym *sym; 150 void *loc; 151 u64 val; 152 153 DEBUGP("Applying relocate section %u to %u\n", 154 relsec, sechdrs[relsec].sh_info); 155 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { 156 /* This is where to make the change */ 157 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 158 + rel[i].r_offset; 159 160 /* This is the symbol it is referring to. Note that all 161 undefined symbols have been resolved. */ 162 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr 163 + ELF64_R_SYM(rel[i].r_info); 164 165 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n", 166 (int)ELF64_R_TYPE(rel[i].r_info), 167 sym->st_value, rel[i].r_addend, (u64)loc); 168 169 val = sym->st_value + rel[i].r_addend; 170 171 switch (ELF64_R_TYPE(rel[i].r_info)) { 172 case R_X86_64_NONE: 173 break; 174 case R_X86_64_64: 175 *(u64 *)loc = val; 176 break; 177 case R_X86_64_32: 178 *(u32 *)loc = val; 179 if (val != *(u32 *)loc) 180 goto overflow; 181 break; 182 case R_X86_64_32S: 183 *(s32 *)loc = val; 184 if ((s64)val != *(s32 *)loc) 185 goto overflow; 186 break; 187 case R_X86_64_PC32: 188 val -= (u64)loc; 189 *(u32 *)loc = val; 190 #if 0 191 if ((s64)val != *(s32 *)loc) 192 goto overflow; 193 #endif 194 break; 195 default: 196 pr_err("%s: Unknown rela relocation: %llu\n", 197 me->name, ELF64_R_TYPE(rel[i].r_info)); 198 return -ENOEXEC; 199 } 200 } 201 return 0; 202 203 overflow: 204 pr_err("overflow in relocation type %d val %Lx\n", 205 (int)ELF64_R_TYPE(rel[i].r_info), val); 206 pr_err("`%s' likely not compiled with -mcmodel=kernel\n", 207 me->name); 208 return -ENOEXEC; 209 } 210 #endif 211 212 int module_finalize(const Elf_Ehdr *hdr, 213 const Elf_Shdr *sechdrs, 214 struct module *me) 215 { 216 const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL, 217 *para = NULL, *orc = NULL, *orc_ip = NULL; 218 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; 219 220 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) { 221 if (!strcmp(".text", secstrings + s->sh_name)) 222 text = s; 223 if (!strcmp(".altinstructions", secstrings + s->sh_name)) 224 alt = s; 225 if (!strcmp(".smp_locks", secstrings + s->sh_name)) 226 locks = s; 227 if (!strcmp(".parainstructions", secstrings + s->sh_name)) 228 para = s; 229 if (!strcmp(".orc_unwind", secstrings + s->sh_name)) 230 orc = s; 231 if (!strcmp(".orc_unwind_ip", secstrings + s->sh_name)) 232 orc_ip = s; 233 } 234 235 if (alt) { 236 /* patch .altinstructions */ 237 void *aseg = (void *)alt->sh_addr; 238 apply_alternatives(aseg, aseg + alt->sh_size); 239 } 240 if (locks && text) { 241 void *lseg = (void *)locks->sh_addr; 242 void *tseg = (void *)text->sh_addr; 243 alternatives_smp_module_add(me, me->name, 244 lseg, lseg + locks->sh_size, 245 tseg, tseg + text->sh_size); 246 } 247 248 if (para) { 249 void *pseg = (void *)para->sh_addr; 250 apply_paravirt(pseg, pseg + para->sh_size); 251 } 252 253 /* make jump label nops */ 254 jump_label_apply_nops(me); 255 256 if (orc && orc_ip) 257 unwind_module_init(me, (void *)orc_ip->sh_addr, orc_ip->sh_size, 258 (void *)orc->sh_addr, orc->sh_size); 259 260 return 0; 261 } 262 263 void module_arch_cleanup(struct module *mod) 264 { 265 alternatives_smp_module_del(mod); 266 } 267