1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * 4 * Copyright (C) 2001 Rusty Russell. 5 * Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org) 6 * Copyright (C) 2005 Thiemo Seufer 7 */ 8 9 #undef DEBUG 10 11 #include <linux/extable.h> 12 #include <linux/moduleloader.h> 13 #include <linux/elf.h> 14 #include <linux/mm.h> 15 #include <linux/numa.h> 16 #include <linux/vmalloc.h> 17 #include <linux/slab.h> 18 #include <linux/fs.h> 19 #include <linux/string.h> 20 #include <linux/kernel.h> 21 #include <linux/spinlock.h> 22 #include <linux/jump_label.h> 23 24 extern void jump_label_apply_nops(struct module *mod); 25 26 struct mips_hi16 { 27 struct mips_hi16 *next; 28 Elf_Addr *addr; 29 Elf_Addr value; 30 }; 31 32 static LIST_HEAD(dbe_list); 33 static DEFINE_SPINLOCK(dbe_lock); 34 35 #ifdef MODULE_START 36 void *module_alloc(unsigned long size) 37 { 38 return __vmalloc_node_range(size, 1, MODULE_START, MODULE_END, 39 GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE, 40 __builtin_return_address(0)); 41 } 42 #endif 43 44 static void apply_r_mips_32(u32 *location, u32 base, Elf_Addr v) 45 { 46 *location = base + v; 47 } 48 49 static int apply_r_mips_26(struct module *me, u32 *location, u32 base, 50 Elf_Addr v) 51 { 52 if (v % 4) { 53 pr_err("module %s: dangerous R_MIPS_26 relocation\n", 54 me->name); 55 return -ENOEXEC; 56 } 57 58 if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) { 59 pr_err("module %s: relocation overflow\n", 60 me->name); 61 return -ENOEXEC; 62 } 63 64 *location = (*location & ~0x03ffffff) | 65 ((base + (v >> 2)) & 0x03ffffff); 66 67 return 0; 68 } 69 70 static int apply_r_mips_hi16(struct module *me, u32 *location, Elf_Addr v, 71 bool rela) 72 { 73 struct mips_hi16 *n; 74 75 if (rela) { 76 *location = (*location & 0xffff0000) | 77 ((((long long) v + 0x8000LL) >> 16) & 0xffff); 78 return 0; 79 } 80 81 /* 82 * We cannot relocate this one now because we don't know the value of 83 * the carry we need to add. Save the information, and let LO16 do the 84 * actual relocation. 85 */ 86 n = kmalloc(sizeof *n, GFP_KERNEL); 87 if (!n) 88 return -ENOMEM; 89 90 n->addr = (Elf_Addr *)location; 91 n->value = v; 92 n->next = me->arch.r_mips_hi16_list; 93 me->arch.r_mips_hi16_list = n; 94 95 return 0; 96 } 97 98 static void free_relocation_chain(struct mips_hi16 *l) 99 { 100 struct mips_hi16 *next; 101 102 while (l) { 103 next = l->next; 104 kfree(l); 105 l = next; 106 } 107 } 108 109 static int apply_r_mips_lo16(struct module *me, u32 *location, 110 u32 base, Elf_Addr v, bool rela) 111 { 112 unsigned long insnlo = base; 113 struct mips_hi16 *l; 114 Elf_Addr val, vallo; 115 116 if (rela) { 117 *location = (*location & 0xffff0000) | (v & 0xffff); 118 return 0; 119 } 120 121 /* Sign extend the addend we extract from the lo insn. */ 122 vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000; 123 124 if (me->arch.r_mips_hi16_list != NULL) { 125 l = me->arch.r_mips_hi16_list; 126 while (l != NULL) { 127 struct mips_hi16 *next; 128 unsigned long insn; 129 130 /* 131 * The value for the HI16 had best be the same. 132 */ 133 if (v != l->value) 134 goto out_danger; 135 136 /* 137 * Do the HI16 relocation. Note that we actually don't 138 * need to know anything about the LO16 itself, except 139 * where to find the low 16 bits of the addend needed 140 * by the LO16. 141 */ 142 insn = *l->addr; 143 val = ((insn & 0xffff) << 16) + vallo; 144 val += v; 145 146 /* 147 * Account for the sign extension that will happen in 148 * the low bits. 149 */ 150 val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff; 151 152 insn = (insn & ~0xffff) | val; 153 *l->addr = insn; 154 155 next = l->next; 156 kfree(l); 157 l = next; 158 } 159 160 me->arch.r_mips_hi16_list = NULL; 161 } 162 163 /* 164 * Ok, we're done with the HI16 relocs. Now deal with the LO16. 165 */ 166 val = v + vallo; 167 insnlo = (insnlo & ~0xffff) | (val & 0xffff); 168 *location = insnlo; 169 170 return 0; 171 172 out_danger: 173 free_relocation_chain(l); 174 me->arch.r_mips_hi16_list = NULL; 175 176 pr_err("module %s: dangerous R_MIPS_LO16 relocation\n", me->name); 177 178 return -ENOEXEC; 179 } 180 181 static int apply_r_mips_pc(struct module *me, u32 *location, u32 base, 182 Elf_Addr v, unsigned int bits) 183 { 184 unsigned long mask = GENMASK(bits - 1, 0); 185 unsigned long se_bits; 186 long offset; 187 188 if (v % 4) { 189 pr_err("module %s: dangerous R_MIPS_PC%u relocation\n", 190 me->name, bits); 191 return -ENOEXEC; 192 } 193 194 /* retrieve & sign extend implicit addend if any */ 195 offset = base & mask; 196 offset |= (offset & BIT(bits - 1)) ? ~mask : 0; 197 198 offset += ((long)v - (long)location) >> 2; 199 200 /* check the sign bit onwards are identical - ie. we didn't overflow */ 201 se_bits = (offset & BIT(bits - 1)) ? ~0ul : 0; 202 if ((offset & ~mask) != (se_bits & ~mask)) { 203 pr_err("module %s: relocation overflow\n", me->name); 204 return -ENOEXEC; 205 } 206 207 *location = (*location & ~mask) | (offset & mask); 208 209 return 0; 210 } 211 212 static int apply_r_mips_pc16(struct module *me, u32 *location, u32 base, 213 Elf_Addr v) 214 { 215 return apply_r_mips_pc(me, location, base, v, 16); 216 } 217 218 static int apply_r_mips_pc21(struct module *me, u32 *location, u32 base, 219 Elf_Addr v) 220 { 221 return apply_r_mips_pc(me, location, base, v, 21); 222 } 223 224 static int apply_r_mips_pc26(struct module *me, u32 *location, u32 base, 225 Elf_Addr v) 226 { 227 return apply_r_mips_pc(me, location, base, v, 26); 228 } 229 230 static int apply_r_mips_64(u32 *location, Elf_Addr v, bool rela) 231 { 232 if (WARN_ON(!rela)) 233 return -EINVAL; 234 235 *(Elf_Addr *)location = v; 236 237 return 0; 238 } 239 240 static int apply_r_mips_higher(u32 *location, Elf_Addr v, bool rela) 241 { 242 if (WARN_ON(!rela)) 243 return -EINVAL; 244 245 *location = (*location & 0xffff0000) | 246 ((((long long)v + 0x80008000LL) >> 32) & 0xffff); 247 248 return 0; 249 } 250 251 static int apply_r_mips_highest(u32 *location, Elf_Addr v, bool rela) 252 { 253 if (WARN_ON(!rela)) 254 return -EINVAL; 255 256 *location = (*location & 0xffff0000) | 257 ((((long long)v + 0x800080008000LL) >> 48) & 0xffff); 258 259 return 0; 260 } 261 262 /** 263 * reloc_handler() - Apply a particular relocation to a module 264 * @type: type of the relocation to apply 265 * @me: the module to apply the reloc to 266 * @location: the address at which the reloc is to be applied 267 * @base: the existing value at location for REL-style; 0 for RELA-style 268 * @v: the value of the reloc, with addend for RELA-style 269 * @rela: indication of is this a RELA (true) or REL (false) relocation 270 * 271 * Each implemented relocation function applies a particular type of 272 * relocation to the module @me. Relocs that may be found in either REL or RELA 273 * variants can be handled by making use of the @base & @v parameters which are 274 * set to values which abstract the difference away from the particular reloc 275 * implementations. 276 * 277 * Return: 0 upon success, else -ERRNO 278 */ 279 static int reloc_handler(u32 type, struct module *me, u32 *location, u32 base, 280 Elf_Addr v, bool rela) 281 { 282 switch (type) { 283 case R_MIPS_NONE: 284 break; 285 case R_MIPS_32: 286 apply_r_mips_32(location, base, v); 287 break; 288 case R_MIPS_26: 289 return apply_r_mips_26(me, location, base, v); 290 case R_MIPS_HI16: 291 return apply_r_mips_hi16(me, location, v, rela); 292 case R_MIPS_LO16: 293 return apply_r_mips_lo16(me, location, base, v, rela); 294 case R_MIPS_PC16: 295 return apply_r_mips_pc16(me, location, base, v); 296 case R_MIPS_PC21_S2: 297 return apply_r_mips_pc21(me, location, base, v); 298 case R_MIPS_PC26_S2: 299 return apply_r_mips_pc26(me, location, base, v); 300 case R_MIPS_64: 301 return apply_r_mips_64(location, v, rela); 302 case R_MIPS_HIGHER: 303 return apply_r_mips_higher(location, v, rela); 304 case R_MIPS_HIGHEST: 305 return apply_r_mips_highest(location, v, rela); 306 default: 307 pr_err("%s: Unknown relocation type %u\n", me->name, type); 308 return -EINVAL; 309 } 310 311 return 0; 312 } 313 314 static int __apply_relocate(Elf_Shdr *sechdrs, const char *strtab, 315 unsigned int symindex, unsigned int relsec, 316 struct module *me, bool rela) 317 { 318 union { 319 Elf_Mips_Rel *rel; 320 Elf_Mips_Rela *rela; 321 } r; 322 Elf_Sym *sym; 323 u32 *location, base; 324 unsigned int i, type; 325 Elf_Addr v; 326 int err = 0; 327 size_t reloc_sz; 328 329 pr_debug("Applying relocate section %u to %u\n", relsec, 330 sechdrs[relsec].sh_info); 331 332 r.rel = (void *)sechdrs[relsec].sh_addr; 333 reloc_sz = rela ? sizeof(*r.rela) : sizeof(*r.rel); 334 me->arch.r_mips_hi16_list = NULL; 335 for (i = 0; i < sechdrs[relsec].sh_size / reloc_sz; i++) { 336 /* This is where to make the change */ 337 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 338 + r.rel->r_offset; 339 /* This is the symbol it is referring to */ 340 sym = (Elf_Sym *)sechdrs[symindex].sh_addr 341 + ELF_MIPS_R_SYM(*r.rel); 342 if (sym->st_value >= -MAX_ERRNO) { 343 /* Ignore unresolved weak symbol */ 344 if (ELF_ST_BIND(sym->st_info) == STB_WEAK) 345 continue; 346 pr_warn("%s: Unknown symbol %s\n", 347 me->name, strtab + sym->st_name); 348 err = -ENOENT; 349 goto out; 350 } 351 352 type = ELF_MIPS_R_TYPE(*r.rel); 353 354 if (rela) { 355 v = sym->st_value + r.rela->r_addend; 356 base = 0; 357 r.rela = &r.rela[1]; 358 } else { 359 v = sym->st_value; 360 base = *location; 361 r.rel = &r.rel[1]; 362 } 363 364 err = reloc_handler(type, me, location, base, v, rela); 365 if (err) 366 goto out; 367 } 368 369 out: 370 /* 371 * Normally the hi16 list should be deallocated at this point. A 372 * malformed binary however could contain a series of R_MIPS_HI16 373 * relocations not followed by a R_MIPS_LO16 relocation, or if we hit 374 * an error processing a reloc we might have gotten here before 375 * reaching the R_MIPS_LO16. In either case, free up the list and 376 * return an error. 377 */ 378 if (me->arch.r_mips_hi16_list) { 379 free_relocation_chain(me->arch.r_mips_hi16_list); 380 me->arch.r_mips_hi16_list = NULL; 381 err = err ?: -ENOEXEC; 382 } 383 384 return err; 385 } 386 387 int apply_relocate(Elf_Shdr *sechdrs, const char *strtab, 388 unsigned int symindex, unsigned int relsec, 389 struct module *me) 390 { 391 return __apply_relocate(sechdrs, strtab, symindex, relsec, me, false); 392 } 393 394 #ifdef CONFIG_MODULES_USE_ELF_RELA 395 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, 396 unsigned int symindex, unsigned int relsec, 397 struct module *me) 398 { 399 return __apply_relocate(sechdrs, strtab, symindex, relsec, me, true); 400 } 401 #endif /* CONFIG_MODULES_USE_ELF_RELA */ 402 403 /* Given an address, look for it in the module exception tables. */ 404 const struct exception_table_entry *search_module_dbetables(unsigned long addr) 405 { 406 unsigned long flags; 407 const struct exception_table_entry *e = NULL; 408 struct mod_arch_specific *dbe; 409 410 spin_lock_irqsave(&dbe_lock, flags); 411 list_for_each_entry(dbe, &dbe_list, dbe_list) { 412 e = search_extable(dbe->dbe_start, 413 dbe->dbe_end - dbe->dbe_start, addr); 414 if (e) 415 break; 416 } 417 spin_unlock_irqrestore(&dbe_lock, flags); 418 419 /* Now, if we found one, we are running inside it now, hence 420 we cannot unload the module, hence no refcnt needed. */ 421 return e; 422 } 423 424 /* Put in dbe list if necessary. */ 425 int module_finalize(const Elf_Ehdr *hdr, 426 const Elf_Shdr *sechdrs, 427 struct module *me) 428 { 429 const Elf_Shdr *s; 430 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; 431 432 if (IS_ENABLED(CONFIG_JUMP_LABEL)) 433 jump_label_apply_nops(me); 434 435 INIT_LIST_HEAD(&me->arch.dbe_list); 436 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) { 437 if (strcmp("__dbe_table", secstrings + s->sh_name) != 0) 438 continue; 439 me->arch.dbe_start = (void *)s->sh_addr; 440 me->arch.dbe_end = (void *)s->sh_addr + s->sh_size; 441 spin_lock_irq(&dbe_lock); 442 list_add(&me->arch.dbe_list, &dbe_list); 443 spin_unlock_irq(&dbe_lock); 444 } 445 return 0; 446 } 447 448 void module_arch_cleanup(struct module *mod) 449 { 450 spin_lock_irq(&dbe_lock); 451 list_del(&mod->arch.dbe_list); 452 spin_unlock_irq(&dbe_lock); 453 } 454