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 25 struct mips_hi16 { 26 struct mips_hi16 *next; 27 Elf_Addr *addr; 28 Elf_Addr value; 29 }; 30 31 static LIST_HEAD(dbe_list); 32 static DEFINE_SPINLOCK(dbe_lock); 33 34 #ifdef MODULE_START 35 void *module_alloc(unsigned long size) 36 { 37 return __vmalloc_node_range(size, 1, MODULE_START, MODULE_END, 38 GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE, 39 __builtin_return_address(0)); 40 } 41 #endif 42 43 static int apply_r_mips_none(struct module *me, u32 *location, 44 u32 base, Elf_Addr v, bool rela) 45 { 46 return 0; 47 } 48 49 static int apply_r_mips_32(struct module *me, u32 *location, 50 u32 base, Elf_Addr v, bool rela) 51 { 52 *location = base + v; 53 54 return 0; 55 } 56 57 static int apply_r_mips_26(struct module *me, u32 *location, 58 u32 base, Elf_Addr v, bool rela) 59 { 60 if (v % 4) { 61 pr_err("module %s: dangerous R_MIPS_26 relocation\n", 62 me->name); 63 return -ENOEXEC; 64 } 65 66 if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) { 67 pr_err("module %s: relocation overflow\n", 68 me->name); 69 return -ENOEXEC; 70 } 71 72 *location = (*location & ~0x03ffffff) | 73 ((base + (v >> 2)) & 0x03ffffff); 74 75 return 0; 76 } 77 78 static int apply_r_mips_hi16(struct module *me, u32 *location, 79 u32 base, Elf_Addr v, bool rela) 80 { 81 struct mips_hi16 *n; 82 83 if (rela) { 84 *location = (*location & 0xffff0000) | 85 ((((long long) v + 0x8000LL) >> 16) & 0xffff); 86 return 0; 87 } 88 89 /* 90 * We cannot relocate this one now because we don't know the value of 91 * the carry we need to add. Save the information, and let LO16 do the 92 * actual relocation. 93 */ 94 n = kmalloc(sizeof *n, GFP_KERNEL); 95 if (!n) 96 return -ENOMEM; 97 98 n->addr = (Elf_Addr *)location; 99 n->value = v; 100 n->next = me->arch.r_mips_hi16_list; 101 me->arch.r_mips_hi16_list = n; 102 103 return 0; 104 } 105 106 static void free_relocation_chain(struct mips_hi16 *l) 107 { 108 struct mips_hi16 *next; 109 110 while (l) { 111 next = l->next; 112 kfree(l); 113 l = next; 114 } 115 } 116 117 static int apply_r_mips_lo16(struct module *me, u32 *location, 118 u32 base, Elf_Addr v, bool rela) 119 { 120 unsigned long insnlo = base; 121 struct mips_hi16 *l; 122 Elf_Addr val, vallo; 123 124 if (rela) { 125 *location = (*location & 0xffff0000) | (v & 0xffff); 126 return 0; 127 } 128 129 /* Sign extend the addend we extract from the lo insn. */ 130 vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000; 131 132 if (me->arch.r_mips_hi16_list != NULL) { 133 l = me->arch.r_mips_hi16_list; 134 while (l != NULL) { 135 struct mips_hi16 *next; 136 unsigned long insn; 137 138 /* 139 * The value for the HI16 had best be the same. 140 */ 141 if (v != l->value) 142 goto out_danger; 143 144 /* 145 * Do the HI16 relocation. Note that we actually don't 146 * need to know anything about the LO16 itself, except 147 * where to find the low 16 bits of the addend needed 148 * by the LO16. 149 */ 150 insn = *l->addr; 151 val = ((insn & 0xffff) << 16) + vallo; 152 val += v; 153 154 /* 155 * Account for the sign extension that will happen in 156 * the low bits. 157 */ 158 val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff; 159 160 insn = (insn & ~0xffff) | val; 161 *l->addr = insn; 162 163 next = l->next; 164 kfree(l); 165 l = next; 166 } 167 168 me->arch.r_mips_hi16_list = NULL; 169 } 170 171 /* 172 * Ok, we're done with the HI16 relocs. Now deal with the LO16. 173 */ 174 val = v + vallo; 175 insnlo = (insnlo & ~0xffff) | (val & 0xffff); 176 *location = insnlo; 177 178 return 0; 179 180 out_danger: 181 free_relocation_chain(l); 182 me->arch.r_mips_hi16_list = NULL; 183 184 pr_err("module %s: dangerous R_MIPS_LO16 relocation\n", me->name); 185 186 return -ENOEXEC; 187 } 188 189 static int apply_r_mips_pc(struct module *me, u32 *location, u32 base, 190 Elf_Addr v, unsigned int bits) 191 { 192 unsigned long mask = GENMASK(bits - 1, 0); 193 unsigned long se_bits; 194 long offset; 195 196 if (v % 4) { 197 pr_err("module %s: dangerous R_MIPS_PC%u relocation\n", 198 me->name, bits); 199 return -ENOEXEC; 200 } 201 202 /* retrieve & sign extend implicit addend if any */ 203 offset = base & mask; 204 offset |= (offset & BIT(bits - 1)) ? ~mask : 0; 205 206 offset += ((long)v - (long)location) >> 2; 207 208 /* check the sign bit onwards are identical - ie. we didn't overflow */ 209 se_bits = (offset & BIT(bits - 1)) ? ~0ul : 0; 210 if ((offset & ~mask) != (se_bits & ~mask)) { 211 pr_err("module %s: relocation overflow\n", me->name); 212 return -ENOEXEC; 213 } 214 215 *location = (*location & ~mask) | (offset & mask); 216 217 return 0; 218 } 219 220 static int apply_r_mips_pc16(struct module *me, u32 *location, 221 u32 base, Elf_Addr v, bool rela) 222 { 223 return apply_r_mips_pc(me, location, base, v, 16); 224 } 225 226 static int apply_r_mips_pc21(struct module *me, u32 *location, 227 u32 base, Elf_Addr v, bool rela) 228 { 229 return apply_r_mips_pc(me, location, base, v, 21); 230 } 231 232 static int apply_r_mips_pc26(struct module *me, u32 *location, 233 u32 base, Elf_Addr v, bool rela) 234 { 235 return apply_r_mips_pc(me, location, base, v, 26); 236 } 237 238 static int apply_r_mips_64(struct module *me, u32 *location, 239 u32 base, Elf_Addr v, bool rela) 240 { 241 if (WARN_ON(!rela)) 242 return -EINVAL; 243 244 *(Elf_Addr *)location = v; 245 246 return 0; 247 } 248 249 static int apply_r_mips_higher(struct module *me, u32 *location, 250 u32 base, Elf_Addr v, bool rela) 251 { 252 if (WARN_ON(!rela)) 253 return -EINVAL; 254 255 *location = (*location & 0xffff0000) | 256 ((((long long)v + 0x80008000LL) >> 32) & 0xffff); 257 258 return 0; 259 } 260 261 static int apply_r_mips_highest(struct module *me, u32 *location, 262 u32 base, Elf_Addr v, bool rela) 263 { 264 if (WARN_ON(!rela)) 265 return -EINVAL; 266 267 *location = (*location & 0xffff0000) | 268 ((((long long)v + 0x800080008000LL) >> 48) & 0xffff); 269 270 return 0; 271 } 272 273 /** 274 * reloc_handler() - Apply a particular relocation to a module 275 * @me: the module to apply the reloc to 276 * @location: the address at which the reloc is to be applied 277 * @base: the existing value at location for REL-style; 0 for RELA-style 278 * @v: the value of the reloc, with addend for RELA-style 279 * 280 * Each implemented reloc_handler function applies a particular type of 281 * relocation to the module @me. Relocs that may be found in either REL or RELA 282 * variants can be handled by making use of the @base & @v parameters which are 283 * set to values which abstract the difference away from the particular reloc 284 * implementations. 285 * 286 * Return: 0 upon success, else -ERRNO 287 */ 288 typedef int (*reloc_handler)(struct module *me, u32 *location, 289 u32 base, Elf_Addr v, bool rela); 290 291 /* The handlers for known reloc types */ 292 static reloc_handler reloc_handlers[] = { 293 [R_MIPS_NONE] = apply_r_mips_none, 294 [R_MIPS_32] = apply_r_mips_32, 295 [R_MIPS_26] = apply_r_mips_26, 296 [R_MIPS_HI16] = apply_r_mips_hi16, 297 [R_MIPS_LO16] = apply_r_mips_lo16, 298 [R_MIPS_PC16] = apply_r_mips_pc16, 299 [R_MIPS_64] = apply_r_mips_64, 300 [R_MIPS_HIGHER] = apply_r_mips_higher, 301 [R_MIPS_HIGHEST] = apply_r_mips_highest, 302 [R_MIPS_PC21_S2] = apply_r_mips_pc21, 303 [R_MIPS_PC26_S2] = apply_r_mips_pc26, 304 }; 305 306 static int __apply_relocate(Elf_Shdr *sechdrs, const char *strtab, 307 unsigned int symindex, unsigned int relsec, 308 struct module *me, bool rela) 309 { 310 union { 311 Elf_Mips_Rel *rel; 312 Elf_Mips_Rela *rela; 313 } r; 314 reloc_handler handler; 315 Elf_Sym *sym; 316 u32 *location, base; 317 unsigned int i, type; 318 Elf_Addr v; 319 int err = 0; 320 size_t reloc_sz; 321 322 pr_debug("Applying relocate section %u to %u\n", relsec, 323 sechdrs[relsec].sh_info); 324 325 r.rel = (void *)sechdrs[relsec].sh_addr; 326 reloc_sz = rela ? sizeof(*r.rela) : sizeof(*r.rel); 327 me->arch.r_mips_hi16_list = NULL; 328 for (i = 0; i < sechdrs[relsec].sh_size / reloc_sz; i++) { 329 /* This is where to make the change */ 330 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 331 + r.rel->r_offset; 332 /* This is the symbol it is referring to */ 333 sym = (Elf_Sym *)sechdrs[symindex].sh_addr 334 + ELF_MIPS_R_SYM(*r.rel); 335 if (sym->st_value >= -MAX_ERRNO) { 336 /* Ignore unresolved weak symbol */ 337 if (ELF_ST_BIND(sym->st_info) == STB_WEAK) 338 continue; 339 pr_warn("%s: Unknown symbol %s\n", 340 me->name, strtab + sym->st_name); 341 err = -ENOENT; 342 goto out; 343 } 344 345 type = ELF_MIPS_R_TYPE(*r.rel); 346 if (type < ARRAY_SIZE(reloc_handlers)) 347 handler = reloc_handlers[type]; 348 else 349 handler = NULL; 350 351 if (!handler) { 352 pr_err("%s: Unknown relocation type %u\n", 353 me->name, type); 354 err = -EINVAL; 355 goto out; 356 } 357 358 if (rela) { 359 v = sym->st_value + r.rela->r_addend; 360 base = 0; 361 r.rela = &r.rela[1]; 362 } else { 363 v = sym->st_value; 364 base = *location; 365 r.rel = &r.rel[1]; 366 } 367 368 err = handler(me, location, base, v, rela); 369 if (err) 370 goto out; 371 } 372 373 out: 374 /* 375 * Normally the hi16 list should be deallocated at this point. A 376 * malformed binary however could contain a series of R_MIPS_HI16 377 * relocations not followed by a R_MIPS_LO16 relocation, or if we hit 378 * an error processing a reloc we might have gotten here before 379 * reaching the R_MIPS_LO16. In either case, free up the list and 380 * return an error. 381 */ 382 if (me->arch.r_mips_hi16_list) { 383 free_relocation_chain(me->arch.r_mips_hi16_list); 384 me->arch.r_mips_hi16_list = NULL; 385 err = err ?: -ENOEXEC; 386 } 387 388 return err; 389 } 390 391 int apply_relocate(Elf_Shdr *sechdrs, const char *strtab, 392 unsigned int symindex, unsigned int relsec, 393 struct module *me) 394 { 395 return __apply_relocate(sechdrs, strtab, symindex, relsec, me, false); 396 } 397 398 #ifdef CONFIG_MODULES_USE_ELF_RELA 399 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, 400 unsigned int symindex, unsigned int relsec, 401 struct module *me) 402 { 403 return __apply_relocate(sechdrs, strtab, symindex, relsec, me, true); 404 } 405 #endif /* CONFIG_MODULES_USE_ELF_RELA */ 406 407 /* Given an address, look for it in the module exception tables. */ 408 const struct exception_table_entry *search_module_dbetables(unsigned long addr) 409 { 410 unsigned long flags; 411 const struct exception_table_entry *e = NULL; 412 struct mod_arch_specific *dbe; 413 414 spin_lock_irqsave(&dbe_lock, flags); 415 list_for_each_entry(dbe, &dbe_list, dbe_list) { 416 e = search_extable(dbe->dbe_start, 417 dbe->dbe_end - dbe->dbe_start, addr); 418 if (e) 419 break; 420 } 421 spin_unlock_irqrestore(&dbe_lock, flags); 422 423 /* Now, if we found one, we are running inside it now, hence 424 we cannot unload the module, hence no refcnt needed. */ 425 return e; 426 } 427 428 /* Put in dbe list if necessary. */ 429 int module_finalize(const Elf_Ehdr *hdr, 430 const Elf_Shdr *sechdrs, 431 struct module *me) 432 { 433 const Elf_Shdr *s; 434 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; 435 436 /* Make jump label nops. */ 437 jump_label_apply_nops(me); 438 439 INIT_LIST_HEAD(&me->arch.dbe_list); 440 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) { 441 if (strcmp("__dbe_table", secstrings + s->sh_name) != 0) 442 continue; 443 me->arch.dbe_start = (void *)s->sh_addr; 444 me->arch.dbe_end = (void *)s->sh_addr + s->sh_size; 445 spin_lock_irq(&dbe_lock); 446 list_add(&me->arch.dbe_list, &dbe_list); 447 spin_unlock_irq(&dbe_lock); 448 } 449 return 0; 450 } 451 452 void module_arch_cleanup(struct module *mod) 453 { 454 spin_lock_irq(&dbe_lock); 455 list_del(&mod->arch.dbe_list); 456 spin_unlock_irq(&dbe_lock); 457 } 458