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