1 /* 2 * This program is free software; you can redistribute it and/or modify 3 * it under the terms of the GNU General Public License as published by 4 * the Free Software Foundation; either version 2 of the License, or 5 * (at your option) any later version. 6 * 7 * This program is distributed in the hope that it will be useful, 8 * but WITHOUT ANY WARRANTY; without even the implied warranty of 9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 10 * GNU General Public License for more details. 11 * 12 * You should have received a copy of the GNU General Public License 13 * along with this program; if not, write to the Free Software 14 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 15 * 16 * Copyright (C) 2001 Rusty Russell. 17 * Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org) 18 * Copyright (C) 2005 Thiemo Seufer 19 */ 20 21 #undef DEBUG 22 23 #include <linux/extable.h> 24 #include <linux/moduleloader.h> 25 #include <linux/elf.h> 26 #include <linux/mm.h> 27 #include <linux/numa.h> 28 #include <linux/vmalloc.h> 29 #include <linux/slab.h> 30 #include <linux/fs.h> 31 #include <linux/string.h> 32 #include <linux/kernel.h> 33 #include <linux/spinlock.h> 34 #include <linux/jump_label.h> 35 36 #include <asm/pgtable.h> /* MODULE_START */ 37 38 struct mips_hi16 { 39 struct mips_hi16 *next; 40 Elf_Addr *addr; 41 Elf_Addr value; 42 }; 43 44 static LIST_HEAD(dbe_list); 45 static DEFINE_SPINLOCK(dbe_lock); 46 47 #ifdef MODULE_START 48 void *module_alloc(unsigned long size) 49 { 50 return __vmalloc_node_range(size, 1, MODULE_START, MODULE_END, 51 GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE, 52 __builtin_return_address(0)); 53 } 54 #endif 55 56 int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v) 57 { 58 return 0; 59 } 60 61 static int apply_r_mips_32_rel(struct module *me, u32 *location, Elf_Addr v) 62 { 63 *location += v; 64 65 return 0; 66 } 67 68 static int apply_r_mips_26_rel(struct module *me, u32 *location, Elf_Addr v) 69 { 70 if (v % 4) { 71 pr_err("module %s: dangerous R_MIPS_26 REL relocation\n", 72 me->name); 73 return -ENOEXEC; 74 } 75 76 if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) { 77 pr_err("module %s: relocation overflow\n", 78 me->name); 79 return -ENOEXEC; 80 } 81 82 *location = (*location & ~0x03ffffff) | 83 ((*location + (v >> 2)) & 0x03ffffff); 84 85 return 0; 86 } 87 88 static int apply_r_mips_hi16_rel(struct module *me, u32 *location, Elf_Addr v) 89 { 90 struct mips_hi16 *n; 91 92 /* 93 * We cannot relocate this one now because we don't know the value of 94 * the carry we need to add. Save the information, and let LO16 do the 95 * actual relocation. 96 */ 97 n = kmalloc(sizeof *n, GFP_KERNEL); 98 if (!n) 99 return -ENOMEM; 100 101 n->addr = (Elf_Addr *)location; 102 n->value = v; 103 n->next = me->arch.r_mips_hi16_list; 104 me->arch.r_mips_hi16_list = n; 105 106 return 0; 107 } 108 109 static void free_relocation_chain(struct mips_hi16 *l) 110 { 111 struct mips_hi16 *next; 112 113 while (l) { 114 next = l->next; 115 kfree(l); 116 l = next; 117 } 118 } 119 120 static int apply_r_mips_lo16_rel(struct module *me, u32 *location, Elf_Addr v) 121 { 122 unsigned long insnlo = *location; 123 struct mips_hi16 *l; 124 Elf_Addr val, vallo; 125 126 /* Sign extend the addend we extract from the lo insn. */ 127 vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000; 128 129 if (me->arch.r_mips_hi16_list != NULL) { 130 l = me->arch.r_mips_hi16_list; 131 while (l != NULL) { 132 struct mips_hi16 *next; 133 unsigned long insn; 134 135 /* 136 * The value for the HI16 had best be the same. 137 */ 138 if (v != l->value) 139 goto out_danger; 140 141 /* 142 * Do the HI16 relocation. Note that we actually don't 143 * need to know anything about the LO16 itself, except 144 * where to find the low 16 bits of the addend needed 145 * by the LO16. 146 */ 147 insn = *l->addr; 148 val = ((insn & 0xffff) << 16) + vallo; 149 val += v; 150 151 /* 152 * Account for the sign extension that will happen in 153 * the low bits. 154 */ 155 val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff; 156 157 insn = (insn & ~0xffff) | val; 158 *l->addr = insn; 159 160 next = l->next; 161 kfree(l); 162 l = next; 163 } 164 165 me->arch.r_mips_hi16_list = NULL; 166 } 167 168 /* 169 * Ok, we're done with the HI16 relocs. Now deal with the LO16. 170 */ 171 val = v + vallo; 172 insnlo = (insnlo & ~0xffff) | (val & 0xffff); 173 *location = insnlo; 174 175 return 0; 176 177 out_danger: 178 free_relocation_chain(l); 179 me->arch.r_mips_hi16_list = NULL; 180 181 pr_err("module %s: dangerous R_MIPS_LO16 REL relocation\n", me->name); 182 183 return -ENOEXEC; 184 } 185 186 static int apply_r_mips_pc_rel(struct module *me, u32 *location, Elf_Addr v, 187 unsigned bits) 188 { 189 unsigned long mask = GENMASK(bits - 1, 0); 190 unsigned long se_bits; 191 long offset; 192 193 if (v % 4) { 194 pr_err("module %s: dangerous R_MIPS_PC%u REL relocation\n", 195 me->name, bits); 196 return -ENOEXEC; 197 } 198 199 /* retrieve & sign extend implicit addend */ 200 offset = *location & mask; 201 offset |= (offset & BIT(bits - 1)) ? ~mask : 0; 202 203 offset += ((long)v - (long)location) >> 2; 204 205 /* check the sign bit onwards are identical - ie. we didn't overflow */ 206 se_bits = (offset & BIT(bits - 1)) ? ~0ul : 0; 207 if ((offset & ~mask) != (se_bits & ~mask)) { 208 pr_err("module %s: relocation overflow\n", me->name); 209 return -ENOEXEC; 210 } 211 212 *location = (*location & ~mask) | (offset & mask); 213 214 return 0; 215 } 216 217 static int apply_r_mips_pc16_rel(struct module *me, u32 *location, Elf_Addr v) 218 { 219 return apply_r_mips_pc_rel(me, location, v, 16); 220 } 221 222 static int apply_r_mips_pc21_rel(struct module *me, u32 *location, Elf_Addr v) 223 { 224 return apply_r_mips_pc_rel(me, location, v, 21); 225 } 226 227 static int apply_r_mips_pc26_rel(struct module *me, u32 *location, Elf_Addr v) 228 { 229 return apply_r_mips_pc_rel(me, location, v, 26); 230 } 231 232 static int (*reloc_handlers_rel[]) (struct module *me, u32 *location, 233 Elf_Addr v) = { 234 [R_MIPS_NONE] = apply_r_mips_none, 235 [R_MIPS_32] = apply_r_mips_32_rel, 236 [R_MIPS_26] = apply_r_mips_26_rel, 237 [R_MIPS_HI16] = apply_r_mips_hi16_rel, 238 [R_MIPS_LO16] = apply_r_mips_lo16_rel, 239 [R_MIPS_PC16] = apply_r_mips_pc16_rel, 240 [R_MIPS_PC21_S2] = apply_r_mips_pc21_rel, 241 [R_MIPS_PC26_S2] = apply_r_mips_pc26_rel, 242 }; 243 244 int apply_relocate(Elf_Shdr *sechdrs, const char *strtab, 245 unsigned int symindex, unsigned int relsec, 246 struct module *me) 247 { 248 Elf_Mips_Rel *rel = (void *) sechdrs[relsec].sh_addr; 249 int (*handler)(struct module *me, u32 *location, Elf_Addr v); 250 Elf_Sym *sym; 251 u32 *location; 252 unsigned int i, type; 253 Elf_Addr v; 254 int res; 255 256 pr_debug("Applying relocate section %u to %u\n", relsec, 257 sechdrs[relsec].sh_info); 258 259 me->arch.r_mips_hi16_list = NULL; 260 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { 261 /* This is where to make the change */ 262 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 263 + rel[i].r_offset; 264 /* This is the symbol it is referring to */ 265 sym = (Elf_Sym *)sechdrs[symindex].sh_addr 266 + ELF_MIPS_R_SYM(rel[i]); 267 if (sym->st_value >= -MAX_ERRNO) { 268 /* Ignore unresolved weak symbol */ 269 if (ELF_ST_BIND(sym->st_info) == STB_WEAK) 270 continue; 271 pr_warn("%s: Unknown symbol %s\n", 272 me->name, strtab + sym->st_name); 273 return -ENOENT; 274 } 275 276 type = ELF_MIPS_R_TYPE(rel[i]); 277 278 if (type < ARRAY_SIZE(reloc_handlers_rel)) 279 handler = reloc_handlers_rel[type]; 280 else 281 handler = NULL; 282 283 if (!handler) { 284 pr_err("%s: Unknown relocation type %u\n", 285 me->name, type); 286 return -EINVAL; 287 } 288 289 v = sym->st_value; 290 res = handler(me, location, v); 291 if (res) 292 return res; 293 } 294 295 /* 296 * Normally the hi16 list should be deallocated at this point. A 297 * malformed binary however could contain a series of R_MIPS_HI16 298 * relocations not followed by a R_MIPS_LO16 relocation. In that 299 * case, free up the list and return an error. 300 */ 301 if (me->arch.r_mips_hi16_list) { 302 free_relocation_chain(me->arch.r_mips_hi16_list); 303 me->arch.r_mips_hi16_list = NULL; 304 305 return -ENOEXEC; 306 } 307 308 return 0; 309 } 310 311 /* Given an address, look for it in the module exception tables. */ 312 const struct exception_table_entry *search_module_dbetables(unsigned long addr) 313 { 314 unsigned long flags; 315 const struct exception_table_entry *e = NULL; 316 struct mod_arch_specific *dbe; 317 318 spin_lock_irqsave(&dbe_lock, flags); 319 list_for_each_entry(dbe, &dbe_list, dbe_list) { 320 e = search_extable(dbe->dbe_start, dbe->dbe_end - 1, addr); 321 if (e) 322 break; 323 } 324 spin_unlock_irqrestore(&dbe_lock, flags); 325 326 /* Now, if we found one, we are running inside it now, hence 327 we cannot unload the module, hence no refcnt needed. */ 328 return e; 329 } 330 331 /* Put in dbe list if necessary. */ 332 int module_finalize(const Elf_Ehdr *hdr, 333 const Elf_Shdr *sechdrs, 334 struct module *me) 335 { 336 const Elf_Shdr *s; 337 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; 338 339 /* Make jump label nops. */ 340 jump_label_apply_nops(me); 341 342 INIT_LIST_HEAD(&me->arch.dbe_list); 343 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) { 344 if (strcmp("__dbe_table", secstrings + s->sh_name) != 0) 345 continue; 346 me->arch.dbe_start = (void *)s->sh_addr; 347 me->arch.dbe_end = (void *)s->sh_addr + s->sh_size; 348 spin_lock_irq(&dbe_lock); 349 list_add(&me->arch.dbe_list, &dbe_list); 350 spin_unlock_irq(&dbe_lock); 351 } 352 return 0; 353 } 354 355 void module_arch_cleanup(struct module *mod) 356 { 357 spin_lock_irq(&dbe_lock); 358 list_del(&mod->arch.dbe_list); 359 spin_unlock_irq(&dbe_lock); 360 } 361