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/moduleloader.h> 24 #include <linux/elf.h> 25 #include <linux/mm.h> 26 #include <linux/numa.h> 27 #include <linux/vmalloc.h> 28 #include <linux/slab.h> 29 #include <linux/fs.h> 30 #include <linux/string.h> 31 #include <linux/kernel.h> 32 #include <linux/spinlock.h> 33 #include <linux/jump_label.h> 34 35 #include <asm/pgtable.h> /* MODULE_START */ 36 37 struct mips_hi16 { 38 struct mips_hi16 *next; 39 Elf_Addr *addr; 40 Elf_Addr value; 41 }; 42 43 static LIST_HEAD(dbe_list); 44 static DEFINE_SPINLOCK(dbe_lock); 45 46 #ifdef MODULE_START 47 void *module_alloc(unsigned long size) 48 { 49 return __vmalloc_node_range(size, 1, MODULE_START, MODULE_END, 50 GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE, 51 __builtin_return_address(0)); 52 } 53 #endif 54 55 int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v) 56 { 57 return 0; 58 } 59 60 static int apply_r_mips_32_rel(struct module *me, u32 *location, Elf_Addr v) 61 { 62 *location += v; 63 64 return 0; 65 } 66 67 static int apply_r_mips_26_rel(struct module *me, u32 *location, Elf_Addr v) 68 { 69 if (v % 4) { 70 pr_err("module %s: dangerous R_MIPS_26 REL relocation\n", 71 me->name); 72 return -ENOEXEC; 73 } 74 75 if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) { 76 pr_err("module %s: relocation overflow\n", 77 me->name); 78 return -ENOEXEC; 79 } 80 81 *location = (*location & ~0x03ffffff) | 82 ((*location + (v >> 2)) & 0x03ffffff); 83 84 return 0; 85 } 86 87 static int apply_r_mips_hi16_rel(struct module *me, u32 *location, Elf_Addr v) 88 { 89 struct mips_hi16 *n; 90 91 /* 92 * We cannot relocate this one now because we don't know the value of 93 * the carry we need to add. Save the information, and let LO16 do the 94 * actual relocation. 95 */ 96 n = kmalloc(sizeof *n, GFP_KERNEL); 97 if (!n) 98 return -ENOMEM; 99 100 n->addr = (Elf_Addr *)location; 101 n->value = v; 102 n->next = me->arch.r_mips_hi16_list; 103 me->arch.r_mips_hi16_list = n; 104 105 return 0; 106 } 107 108 static void free_relocation_chain(struct mips_hi16 *l) 109 { 110 struct mips_hi16 *next; 111 112 while (l) { 113 next = l->next; 114 kfree(l); 115 l = next; 116 } 117 } 118 119 static int apply_r_mips_lo16_rel(struct module *me, u32 *location, Elf_Addr v) 120 { 121 unsigned long insnlo = *location; 122 struct mips_hi16 *l; 123 Elf_Addr val, vallo; 124 125 /* Sign extend the addend we extract from the lo insn. */ 126 vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000; 127 128 if (me->arch.r_mips_hi16_list != NULL) { 129 l = me->arch.r_mips_hi16_list; 130 while (l != NULL) { 131 struct mips_hi16 *next; 132 unsigned long insn; 133 134 /* 135 * The value for the HI16 had best be the same. 136 */ 137 if (v != l->value) 138 goto out_danger; 139 140 /* 141 * Do the HI16 relocation. Note that we actually don't 142 * need to know anything about the LO16 itself, except 143 * where to find the low 16 bits of the addend needed 144 * by the LO16. 145 */ 146 insn = *l->addr; 147 val = ((insn & 0xffff) << 16) + vallo; 148 val += v; 149 150 /* 151 * Account for the sign extension that will happen in 152 * the low bits. 153 */ 154 val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff; 155 156 insn = (insn & ~0xffff) | val; 157 *l->addr = insn; 158 159 next = l->next; 160 kfree(l); 161 l = next; 162 } 163 164 me->arch.r_mips_hi16_list = NULL; 165 } 166 167 /* 168 * Ok, we're done with the HI16 relocs. Now deal with the LO16. 169 */ 170 val = v + vallo; 171 insnlo = (insnlo & ~0xffff) | (val & 0xffff); 172 *location = insnlo; 173 174 return 0; 175 176 out_danger: 177 free_relocation_chain(l); 178 me->arch.r_mips_hi16_list = NULL; 179 180 pr_err("module %s: dangerous R_MIPS_LO16 REL relocation\n", me->name); 181 182 return -ENOEXEC; 183 } 184 185 static int apply_r_mips_pc_rel(struct module *me, u32 *location, Elf_Addr v, 186 unsigned bits) 187 { 188 unsigned long mask = GENMASK(bits - 1, 0); 189 unsigned long se_bits; 190 long offset; 191 192 if (v % 4) { 193 pr_err("module %s: dangerous R_MIPS_PC%u REL relocation\n", 194 me->name, bits); 195 return -ENOEXEC; 196 } 197 198 /* retrieve & sign extend implicit addend */ 199 offset = *location & mask; 200 offset |= (offset & BIT(bits - 1)) ? ~mask : 0; 201 202 offset += ((long)v - (long)location) >> 2; 203 204 /* check the sign bit onwards are identical - ie. we didn't overflow */ 205 se_bits = (offset & BIT(bits - 1)) ? ~0ul : 0; 206 if ((offset & ~mask) != (se_bits & ~mask)) { 207 pr_err("module %s: relocation overflow\n", me->name); 208 return -ENOEXEC; 209 } 210 211 *location = (*location & ~mask) | (offset & mask); 212 213 return 0; 214 } 215 216 static int apply_r_mips_pc16_rel(struct module *me, u32 *location, Elf_Addr v) 217 { 218 return apply_r_mips_pc_rel(me, location, v, 16); 219 } 220 221 static int apply_r_mips_pc21_rel(struct module *me, u32 *location, Elf_Addr v) 222 { 223 return apply_r_mips_pc_rel(me, location, v, 21); 224 } 225 226 static int apply_r_mips_pc26_rel(struct module *me, u32 *location, Elf_Addr v) 227 { 228 return apply_r_mips_pc_rel(me, location, v, 26); 229 } 230 231 static int (*reloc_handlers_rel[]) (struct module *me, u32 *location, 232 Elf_Addr v) = { 233 [R_MIPS_NONE] = apply_r_mips_none, 234 [R_MIPS_32] = apply_r_mips_32_rel, 235 [R_MIPS_26] = apply_r_mips_26_rel, 236 [R_MIPS_HI16] = apply_r_mips_hi16_rel, 237 [R_MIPS_LO16] = apply_r_mips_lo16_rel, 238 [R_MIPS_PC16] = apply_r_mips_pc16_rel, 239 [R_MIPS_PC21_S2] = apply_r_mips_pc21_rel, 240 [R_MIPS_PC26_S2] = apply_r_mips_pc26_rel, 241 }; 242 243 int apply_relocate(Elf_Shdr *sechdrs, const char *strtab, 244 unsigned int symindex, unsigned int relsec, 245 struct module *me) 246 { 247 Elf_Mips_Rel *rel = (void *) sechdrs[relsec].sh_addr; 248 int (*handler)(struct module *me, u32 *location, Elf_Addr v); 249 Elf_Sym *sym; 250 u32 *location; 251 unsigned int i, type; 252 Elf_Addr v; 253 int res; 254 255 pr_debug("Applying relocate section %u to %u\n", relsec, 256 sechdrs[relsec].sh_info); 257 258 me->arch.r_mips_hi16_list = NULL; 259 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { 260 /* This is where to make the change */ 261 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 262 + rel[i].r_offset; 263 /* This is the symbol it is referring to */ 264 sym = (Elf_Sym *)sechdrs[symindex].sh_addr 265 + ELF_MIPS_R_SYM(rel[i]); 266 if (sym->st_value >= -MAX_ERRNO) { 267 /* Ignore unresolved weak symbol */ 268 if (ELF_ST_BIND(sym->st_info) == STB_WEAK) 269 continue; 270 pr_warn("%s: Unknown symbol %s\n", 271 me->name, strtab + sym->st_name); 272 return -ENOENT; 273 } 274 275 type = ELF_MIPS_R_TYPE(rel[i]); 276 277 if (type < ARRAY_SIZE(reloc_handlers_rel)) 278 handler = reloc_handlers_rel[type]; 279 else 280 handler = NULL; 281 282 if (!handler) { 283 pr_err("%s: Unknown relocation type %u\n", 284 me->name, type); 285 return -EINVAL; 286 } 287 288 v = sym->st_value; 289 res = handler(me, location, v); 290 if (res) 291 return res; 292 } 293 294 /* 295 * Normally the hi16 list should be deallocated at this point. A 296 * malformed binary however could contain a series of R_MIPS_HI16 297 * relocations not followed by a R_MIPS_LO16 relocation. In that 298 * case, free up the list and return an error. 299 */ 300 if (me->arch.r_mips_hi16_list) { 301 free_relocation_chain(me->arch.r_mips_hi16_list); 302 me->arch.r_mips_hi16_list = NULL; 303 304 return -ENOEXEC; 305 } 306 307 return 0; 308 } 309 310 /* Given an address, look for it in the module exception tables. */ 311 const struct exception_table_entry *search_module_dbetables(unsigned long addr) 312 { 313 unsigned long flags; 314 const struct exception_table_entry *e = NULL; 315 struct mod_arch_specific *dbe; 316 317 spin_lock_irqsave(&dbe_lock, flags); 318 list_for_each_entry(dbe, &dbe_list, dbe_list) { 319 e = search_extable(dbe->dbe_start, dbe->dbe_end - 1, addr); 320 if (e) 321 break; 322 } 323 spin_unlock_irqrestore(&dbe_lock, flags); 324 325 /* Now, if we found one, we are running inside it now, hence 326 we cannot unload the module, hence no refcnt needed. */ 327 return e; 328 } 329 330 /* Put in dbe list if necessary. */ 331 int module_finalize(const Elf_Ehdr *hdr, 332 const Elf_Shdr *sechdrs, 333 struct module *me) 334 { 335 const Elf_Shdr *s; 336 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; 337 338 /* Make jump label nops. */ 339 jump_label_apply_nops(me); 340 341 INIT_LIST_HEAD(&me->arch.dbe_list); 342 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) { 343 if (strcmp("__dbe_table", secstrings + s->sh_name) != 0) 344 continue; 345 me->arch.dbe_start = (void *)s->sh_addr; 346 me->arch.dbe_end = (void *)s->sh_addr + s->sh_size; 347 spin_lock_irq(&dbe_lock); 348 list_add(&me->arch.dbe_list, &dbe_list); 349 spin_unlock_irq(&dbe_lock); 350 } 351 return 0; 352 } 353 354 void module_arch_cleanup(struct module *mod) 355 { 356 spin_lock_irq(&dbe_lock); 357 list_del(&mod->arch.dbe_list); 358 spin_unlock_irq(&dbe_lock); 359 } 360