1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/arch/arm/kernel/module.c 4 * 5 * Copyright (C) 2002 Russell King. 6 * Modified for nommu by Hyok S. Choi 7 * 8 * Module allocation method suggested by Andi Kleen. 9 */ 10 #include <linux/module.h> 11 #include <linux/moduleloader.h> 12 #include <linux/kernel.h> 13 #include <linux/mm.h> 14 #include <linux/elf.h> 15 #include <linux/fs.h> 16 #include <linux/string.h> 17 18 #include <asm/sections.h> 19 #include <asm/smp_plat.h> 20 #include <asm/unwind.h> 21 #include <asm/opcodes.h> 22 23 bool module_init_section(const char *name) 24 { 25 return strstarts(name, ".init") || 26 strstarts(name, ".ARM.extab.init") || 27 strstarts(name, ".ARM.exidx.init"); 28 } 29 30 bool module_exit_section(const char *name) 31 { 32 return strstarts(name, ".exit") || 33 strstarts(name, ".ARM.extab.exit") || 34 strstarts(name, ".ARM.exidx.exit"); 35 } 36 37 #ifdef CONFIG_ARM_HAS_GROUP_RELOCS 38 /* 39 * This implements the partitioning algorithm for group relocations as 40 * documented in the ARM AArch32 ELF psABI (IHI 0044). 41 * 42 * A single PC-relative symbol reference is divided in up to 3 add or subtract 43 * operations, where the final one could be incorporated into a load/store 44 * instruction with immediate offset. E.g., 45 * 46 * ADD Rd, PC, #... or ADD Rd, PC, #... 47 * ADD Rd, Rd, #... ADD Rd, Rd, #... 48 * LDR Rd, [Rd, #...] ADD Rd, Rd, #... 49 * 50 * The latter has a guaranteed range of only 16 MiB (3x8 == 24 bits), so it is 51 * of limited use in the kernel. However, the ADD/ADD/LDR combo has a range of 52 * -/+ 256 MiB, (2x8 + 12 == 28 bits), which means it has sufficient range for 53 * any in-kernel symbol reference (unless module PLTs are being used). 54 * 55 * The main advantage of this approach over the typical pattern using a literal 56 * load is that literal loads may miss in the D-cache, and generally lead to 57 * lower cache efficiency for variables that are referenced often from many 58 * different places in the code. 59 */ 60 static u32 get_group_rem(u32 group, u32 *offset) 61 { 62 u32 val = *offset; 63 u32 shift; 64 do { 65 shift = val ? (31 - __fls(val)) & ~1 : 32; 66 *offset = val; 67 if (!val) 68 break; 69 val &= 0xffffff >> shift; 70 } while (group--); 71 return shift; 72 } 73 #endif 74 75 int 76 apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex, 77 unsigned int relindex, struct module *module) 78 { 79 Elf32_Shdr *symsec = sechdrs + symindex; 80 Elf32_Shdr *relsec = sechdrs + relindex; 81 Elf32_Shdr *dstsec = sechdrs + relsec->sh_info; 82 Elf32_Rel *rel = (void *)relsec->sh_addr; 83 unsigned int i; 84 85 for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++, rel++) { 86 unsigned long loc; 87 Elf32_Sym *sym; 88 const char *symname; 89 #ifdef CONFIG_ARM_HAS_GROUP_RELOCS 90 u32 shift, group = 1; 91 #endif 92 s32 offset; 93 u32 tmp; 94 #ifdef CONFIG_THUMB2_KERNEL 95 u32 upper, lower, sign, j1, j2; 96 #endif 97 98 offset = ELF32_R_SYM(rel->r_info); 99 if (offset < 0 || offset > (symsec->sh_size / sizeof(Elf32_Sym))) { 100 pr_err("%s: section %u reloc %u: bad relocation sym offset\n", 101 module->name, relindex, i); 102 return -ENOEXEC; 103 } 104 105 sym = ((Elf32_Sym *)symsec->sh_addr) + offset; 106 symname = strtab + sym->st_name; 107 108 if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(u32)) { 109 pr_err("%s: section %u reloc %u sym '%s': out of bounds relocation, offset %d size %u\n", 110 module->name, relindex, i, symname, 111 rel->r_offset, dstsec->sh_size); 112 return -ENOEXEC; 113 } 114 115 loc = dstsec->sh_addr + rel->r_offset; 116 117 switch (ELF32_R_TYPE(rel->r_info)) { 118 case R_ARM_NONE: 119 /* ignore */ 120 break; 121 122 case R_ARM_ABS32: 123 case R_ARM_TARGET1: 124 *(u32 *)loc += sym->st_value; 125 break; 126 127 case R_ARM_PC24: 128 case R_ARM_CALL: 129 case R_ARM_JUMP24: 130 if (sym->st_value & 3) { 131 pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (ARM -> Thumb)\n", 132 module->name, relindex, i, symname); 133 return -ENOEXEC; 134 } 135 136 offset = __mem_to_opcode_arm(*(u32 *)loc); 137 offset = (offset & 0x00ffffff) << 2; 138 offset = sign_extend32(offset, 25); 139 140 offset += sym->st_value - loc; 141 142 /* 143 * Route through a PLT entry if 'offset' exceeds the 144 * supported range. Note that 'offset + loc + 8' 145 * contains the absolute jump target, i.e., 146 * @sym + addend, corrected for the +8 PC bias. 147 */ 148 if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) && 149 (offset <= (s32)0xfe000000 || 150 offset >= (s32)0x02000000)) 151 offset = get_module_plt(module, loc, 152 offset + loc + 8) 153 - loc - 8; 154 155 if (offset <= (s32)0xfe000000 || 156 offset >= (s32)0x02000000) { 157 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n", 158 module->name, relindex, i, symname, 159 ELF32_R_TYPE(rel->r_info), loc, 160 sym->st_value); 161 return -ENOEXEC; 162 } 163 164 offset >>= 2; 165 offset &= 0x00ffffff; 166 167 *(u32 *)loc &= __opcode_to_mem_arm(0xff000000); 168 *(u32 *)loc |= __opcode_to_mem_arm(offset); 169 break; 170 171 case R_ARM_V4BX: 172 /* Preserve Rm and the condition code. Alter 173 * other bits to re-code instruction as 174 * MOV PC,Rm. 175 */ 176 *(u32 *)loc &= __opcode_to_mem_arm(0xf000000f); 177 *(u32 *)loc |= __opcode_to_mem_arm(0x01a0f000); 178 break; 179 180 case R_ARM_PREL31: 181 offset = (*(s32 *)loc << 1) >> 1; /* sign extend */ 182 offset += sym->st_value - loc; 183 if (offset >= 0x40000000 || offset < -0x40000000) { 184 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n", 185 module->name, relindex, i, symname, 186 ELF32_R_TYPE(rel->r_info), loc, 187 sym->st_value); 188 return -ENOEXEC; 189 } 190 *(u32 *)loc &= 0x80000000; 191 *(u32 *)loc |= offset & 0x7fffffff; 192 break; 193 194 case R_ARM_REL32: 195 *(u32 *)loc += sym->st_value - loc; 196 break; 197 198 case R_ARM_MOVW_ABS_NC: 199 case R_ARM_MOVT_ABS: 200 case R_ARM_MOVW_PREL_NC: 201 case R_ARM_MOVT_PREL: 202 offset = tmp = __mem_to_opcode_arm(*(u32 *)loc); 203 offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff); 204 offset = sign_extend32(offset, 15); 205 206 offset += sym->st_value; 207 if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_PREL || 208 ELF32_R_TYPE(rel->r_info) == R_ARM_MOVW_PREL_NC) 209 offset -= loc; 210 if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS || 211 ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_PREL) 212 offset >>= 16; 213 214 tmp &= 0xfff0f000; 215 tmp |= ((offset & 0xf000) << 4) | 216 (offset & 0x0fff); 217 218 *(u32 *)loc = __opcode_to_mem_arm(tmp); 219 break; 220 221 #ifdef CONFIG_ARM_HAS_GROUP_RELOCS 222 case R_ARM_ALU_PC_G0_NC: 223 group = 0; 224 fallthrough; 225 case R_ARM_ALU_PC_G1_NC: 226 tmp = __mem_to_opcode_arm(*(u32 *)loc); 227 offset = ror32(tmp & 0xff, (tmp & 0xf00) >> 7); 228 if (tmp & BIT(22)) 229 offset = -offset; 230 offset += sym->st_value - loc; 231 if (offset < 0) { 232 offset = -offset; 233 tmp = (tmp & ~BIT(23)) | BIT(22); // SUB opcode 234 } else { 235 tmp = (tmp & ~BIT(22)) | BIT(23); // ADD opcode 236 } 237 238 shift = get_group_rem(group, &offset); 239 if (shift < 24) { 240 offset >>= 24 - shift; 241 offset |= (shift + 8) << 7; 242 } 243 *(u32 *)loc = __opcode_to_mem_arm((tmp & ~0xfff) | offset); 244 break; 245 246 case R_ARM_LDR_PC_G2: 247 tmp = __mem_to_opcode_arm(*(u32 *)loc); 248 offset = tmp & 0xfff; 249 if (~tmp & BIT(23)) // U bit cleared? 250 offset = -offset; 251 offset += sym->st_value - loc; 252 if (offset < 0) { 253 offset = -offset; 254 tmp &= ~BIT(23); // clear U bit 255 } else { 256 tmp |= BIT(23); // set U bit 257 } 258 get_group_rem(2, &offset); 259 260 if (offset > 0xfff) { 261 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n", 262 module->name, relindex, i, symname, 263 ELF32_R_TYPE(rel->r_info), loc, 264 sym->st_value); 265 return -ENOEXEC; 266 } 267 *(u32 *)loc = __opcode_to_mem_arm((tmp & ~0xfff) | offset); 268 break; 269 #endif 270 #ifdef CONFIG_THUMB2_KERNEL 271 case R_ARM_THM_CALL: 272 case R_ARM_THM_JUMP24: 273 /* 274 * For function symbols, only Thumb addresses are 275 * allowed (no interworking). 276 * 277 * For non-function symbols, the destination 278 * has no specific ARM/Thumb disposition, so 279 * the branch is resolved under the assumption 280 * that interworking is not required. 281 */ 282 if (ELF32_ST_TYPE(sym->st_info) == STT_FUNC && 283 !(sym->st_value & 1)) { 284 pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (Thumb -> ARM)\n", 285 module->name, relindex, i, symname); 286 return -ENOEXEC; 287 } 288 289 upper = __mem_to_opcode_thumb16(*(u16 *)loc); 290 lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2)); 291 292 /* 293 * 25 bit signed address range (Thumb-2 BL and B.W 294 * instructions): 295 * S:I1:I2:imm10:imm11:0 296 * where: 297 * S = upper[10] = offset[24] 298 * I1 = ~(J1 ^ S) = offset[23] 299 * I2 = ~(J2 ^ S) = offset[22] 300 * imm10 = upper[9:0] = offset[21:12] 301 * imm11 = lower[10:0] = offset[11:1] 302 * J1 = lower[13] 303 * J2 = lower[11] 304 */ 305 sign = (upper >> 10) & 1; 306 j1 = (lower >> 13) & 1; 307 j2 = (lower >> 11) & 1; 308 offset = (sign << 24) | ((~(j1 ^ sign) & 1) << 23) | 309 ((~(j2 ^ sign) & 1) << 22) | 310 ((upper & 0x03ff) << 12) | 311 ((lower & 0x07ff) << 1); 312 offset = sign_extend32(offset, 24); 313 offset += sym->st_value - loc; 314 315 /* 316 * Route through a PLT entry if 'offset' exceeds the 317 * supported range. 318 */ 319 if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) && 320 (offset <= (s32)0xff000000 || 321 offset >= (s32)0x01000000)) 322 offset = get_module_plt(module, loc, 323 offset + loc + 4) 324 - loc - 4; 325 326 if (offset <= (s32)0xff000000 || 327 offset >= (s32)0x01000000) { 328 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n", 329 module->name, relindex, i, symname, 330 ELF32_R_TYPE(rel->r_info), loc, 331 sym->st_value); 332 return -ENOEXEC; 333 } 334 335 sign = (offset >> 24) & 1; 336 j1 = sign ^ (~(offset >> 23) & 1); 337 j2 = sign ^ (~(offset >> 22) & 1); 338 upper = (u16)((upper & 0xf800) | (sign << 10) | 339 ((offset >> 12) & 0x03ff)); 340 lower = (u16)((lower & 0xd000) | 341 (j1 << 13) | (j2 << 11) | 342 ((offset >> 1) & 0x07ff)); 343 344 *(u16 *)loc = __opcode_to_mem_thumb16(upper); 345 *(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower); 346 break; 347 348 case R_ARM_THM_MOVW_ABS_NC: 349 case R_ARM_THM_MOVT_ABS: 350 case R_ARM_THM_MOVW_PREL_NC: 351 case R_ARM_THM_MOVT_PREL: 352 upper = __mem_to_opcode_thumb16(*(u16 *)loc); 353 lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2)); 354 355 /* 356 * MOVT/MOVW instructions encoding in Thumb-2: 357 * 358 * i = upper[10] 359 * imm4 = upper[3:0] 360 * imm3 = lower[14:12] 361 * imm8 = lower[7:0] 362 * 363 * imm16 = imm4:i:imm3:imm8 364 */ 365 offset = ((upper & 0x000f) << 12) | 366 ((upper & 0x0400) << 1) | 367 ((lower & 0x7000) >> 4) | (lower & 0x00ff); 368 offset = sign_extend32(offset, 15); 369 offset += sym->st_value; 370 371 if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_PREL || 372 ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVW_PREL_NC) 373 offset -= loc; 374 if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS || 375 ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_PREL) 376 offset >>= 16; 377 378 upper = (u16)((upper & 0xfbf0) | 379 ((offset & 0xf000) >> 12) | 380 ((offset & 0x0800) >> 1)); 381 lower = (u16)((lower & 0x8f00) | 382 ((offset & 0x0700) << 4) | 383 (offset & 0x00ff)); 384 *(u16 *)loc = __opcode_to_mem_thumb16(upper); 385 *(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower); 386 break; 387 #endif 388 389 default: 390 pr_err("%s: unknown relocation: %u\n", 391 module->name, ELF32_R_TYPE(rel->r_info)); 392 return -ENOEXEC; 393 } 394 } 395 return 0; 396 } 397 398 static const Elf_Shdr *find_mod_section(const Elf32_Ehdr *hdr, 399 const Elf_Shdr *sechdrs, const char *name) 400 { 401 const Elf_Shdr *s, *se; 402 const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; 403 404 for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++) 405 if (strcmp(name, secstrs + s->sh_name) == 0) 406 return s; 407 408 return NULL; 409 } 410 411 extern void fixup_pv_table(const void *, unsigned long); 412 extern void fixup_smp(const void *, unsigned long); 413 414 int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs, 415 struct module *mod) 416 { 417 const Elf_Shdr *s = NULL; 418 #ifdef CONFIG_ARM_UNWIND 419 const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; 420 const Elf_Shdr *sechdrs_end = sechdrs + hdr->e_shnum; 421 struct list_head *unwind_list = &mod->arch.unwind_list; 422 423 INIT_LIST_HEAD(unwind_list); 424 mod->arch.init_table = NULL; 425 426 for (s = sechdrs; s < sechdrs_end; s++) { 427 const char *secname = secstrs + s->sh_name; 428 const char *txtname; 429 const Elf_Shdr *txt_sec; 430 431 if (!(s->sh_flags & SHF_ALLOC) || 432 s->sh_type != ELF_SECTION_UNWIND) 433 continue; 434 435 if (!strcmp(".ARM.exidx", secname)) 436 txtname = ".text"; 437 else 438 txtname = secname + strlen(".ARM.exidx"); 439 txt_sec = find_mod_section(hdr, sechdrs, txtname); 440 441 if (txt_sec) { 442 struct unwind_table *table = 443 unwind_table_add(s->sh_addr, 444 s->sh_size, 445 txt_sec->sh_addr, 446 txt_sec->sh_size); 447 448 list_add(&table->mod_list, unwind_list); 449 450 /* save init table for module_arch_freeing_init */ 451 if (strcmp(".ARM.exidx.init.text", secname) == 0) 452 mod->arch.init_table = table; 453 } 454 } 455 #endif 456 #ifdef CONFIG_ARM_PATCH_PHYS_VIRT 457 s = find_mod_section(hdr, sechdrs, ".pv_table"); 458 if (s) 459 fixup_pv_table((void *)s->sh_addr, s->sh_size); 460 #endif 461 s = find_mod_section(hdr, sechdrs, ".alt.smp.init"); 462 if (s && !is_smp()) 463 #ifdef CONFIG_SMP_ON_UP 464 fixup_smp((void *)s->sh_addr, s->sh_size); 465 #else 466 return -EINVAL; 467 #endif 468 return 0; 469 } 470 471 void 472 module_arch_cleanup(struct module *mod) 473 { 474 #ifdef CONFIG_ARM_UNWIND 475 struct unwind_table *tmp; 476 struct unwind_table *n; 477 478 list_for_each_entry_safe(tmp, n, 479 &mod->arch.unwind_list, mod_list) { 480 list_del(&tmp->mod_list); 481 unwind_table_del(tmp); 482 } 483 mod->arch.init_table = NULL; 484 #endif 485 } 486 487 void __weak module_arch_freeing_init(struct module *mod) 488 { 489 #ifdef CONFIG_ARM_UNWIND 490 struct unwind_table *init = mod->arch.init_table; 491 492 if (init) { 493 mod->arch.init_table = NULL; 494 list_del(&init->mod_list); 495 unwind_table_del(init); 496 } 497 #endif 498 } 499