1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * 4 * Copyright (C) 2017 Zihao Yu 5 */ 6 7 #include <linux/elf.h> 8 #include <linux/err.h> 9 #include <linux/errno.h> 10 #include <linux/hashtable.h> 11 #include <linux/kernel.h> 12 #include <linux/log2.h> 13 #include <linux/moduleloader.h> 14 #include <linux/sizes.h> 15 #include <linux/pgtable.h> 16 #include <asm/alternative.h> 17 #include <asm/sections.h> 18 19 struct used_bucket { 20 struct list_head head; 21 struct hlist_head *bucket; 22 }; 23 24 struct relocation_head { 25 struct hlist_node node; 26 struct list_head *rel_entry; 27 void *location; 28 }; 29 30 struct relocation_entry { 31 struct list_head head; 32 Elf_Addr value; 33 unsigned int type; 34 }; 35 36 struct relocation_handlers { 37 int (*reloc_handler)(struct module *me, void *location, Elf_Addr v); 38 int (*accumulate_handler)(struct module *me, void *location, 39 long buffer); 40 }; 41 42 /* 43 * The auipc+jalr instruction pair can reach any PC-relative offset 44 * in the range [-2^31 - 2^11, 2^31 - 2^11) 45 */ 46 static bool riscv_insn_valid_32bit_offset(ptrdiff_t val) 47 { 48 #ifdef CONFIG_32BIT 49 return true; 50 #else 51 return (-(1L << 31) - (1L << 11)) <= val && val < ((1L << 31) - (1L << 11)); 52 #endif 53 } 54 55 static int riscv_insn_rmw(void *location, u32 keep, u32 set) 56 { 57 __le16 *parcel = location; 58 u32 insn = (u32)le16_to_cpu(parcel[0]) | (u32)le16_to_cpu(parcel[1]) << 16; 59 60 insn &= keep; 61 insn |= set; 62 63 parcel[0] = cpu_to_le16(insn); 64 parcel[1] = cpu_to_le16(insn >> 16); 65 return 0; 66 } 67 68 static int riscv_insn_rvc_rmw(void *location, u16 keep, u16 set) 69 { 70 __le16 *parcel = location; 71 u16 insn = le16_to_cpu(*parcel); 72 73 insn &= keep; 74 insn |= set; 75 76 *parcel = cpu_to_le16(insn); 77 return 0; 78 } 79 80 static int apply_r_riscv_32_rela(struct module *me, void *location, Elf_Addr v) 81 { 82 if (v != (u32)v) { 83 pr_err("%s: value %016llx out of range for 32-bit field\n", 84 me->name, (long long)v); 85 return -EINVAL; 86 } 87 *(u32 *)location = v; 88 return 0; 89 } 90 91 static int apply_r_riscv_64_rela(struct module *me, void *location, Elf_Addr v) 92 { 93 *(u64 *)location = v; 94 return 0; 95 } 96 97 static int apply_r_riscv_branch_rela(struct module *me, void *location, 98 Elf_Addr v) 99 { 100 ptrdiff_t offset = (void *)v - location; 101 u32 imm12 = (offset & 0x1000) << (31 - 12); 102 u32 imm11 = (offset & 0x800) >> (11 - 7); 103 u32 imm10_5 = (offset & 0x7e0) << (30 - 10); 104 u32 imm4_1 = (offset & 0x1e) << (11 - 4); 105 106 return riscv_insn_rmw(location, 0x1fff07f, imm12 | imm11 | imm10_5 | imm4_1); 107 } 108 109 static int apply_r_riscv_jal_rela(struct module *me, void *location, 110 Elf_Addr v) 111 { 112 ptrdiff_t offset = (void *)v - location; 113 u32 imm20 = (offset & 0x100000) << (31 - 20); 114 u32 imm19_12 = (offset & 0xff000); 115 u32 imm11 = (offset & 0x800) << (20 - 11); 116 u32 imm10_1 = (offset & 0x7fe) << (30 - 10); 117 118 return riscv_insn_rmw(location, 0xfff, imm20 | imm19_12 | imm11 | imm10_1); 119 } 120 121 static int apply_r_riscv_rvc_branch_rela(struct module *me, void *location, 122 Elf_Addr v) 123 { 124 ptrdiff_t offset = (void *)v - location; 125 u16 imm8 = (offset & 0x100) << (12 - 8); 126 u16 imm7_6 = (offset & 0xc0) >> (6 - 5); 127 u16 imm5 = (offset & 0x20) >> (5 - 2); 128 u16 imm4_3 = (offset & 0x18) << (12 - 5); 129 u16 imm2_1 = (offset & 0x6) << (12 - 10); 130 131 return riscv_insn_rvc_rmw(location, 0xe383, 132 imm8 | imm7_6 | imm5 | imm4_3 | imm2_1); 133 } 134 135 static int apply_r_riscv_rvc_jump_rela(struct module *me, void *location, 136 Elf_Addr v) 137 { 138 ptrdiff_t offset = (void *)v - location; 139 u16 imm11 = (offset & 0x800) << (12 - 11); 140 u16 imm10 = (offset & 0x400) >> (10 - 8); 141 u16 imm9_8 = (offset & 0x300) << (12 - 11); 142 u16 imm7 = (offset & 0x80) >> (7 - 6); 143 u16 imm6 = (offset & 0x40) << (12 - 11); 144 u16 imm5 = (offset & 0x20) >> (5 - 2); 145 u16 imm4 = (offset & 0x10) << (12 - 5); 146 u16 imm3_1 = (offset & 0xe) << (12 - 10); 147 148 return riscv_insn_rvc_rmw(location, 0xe003, 149 imm11 | imm10 | imm9_8 | imm7 | imm6 | imm5 | imm4 | imm3_1); 150 } 151 152 static int apply_r_riscv_pcrel_hi20_rela(struct module *me, void *location, 153 Elf_Addr v) 154 { 155 ptrdiff_t offset = (void *)v - location; 156 157 if (!riscv_insn_valid_32bit_offset(offset)) { 158 pr_err( 159 "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n", 160 me->name, (long long)v, location); 161 return -EINVAL; 162 } 163 164 return riscv_insn_rmw(location, 0xfff, (offset + 0x800) & 0xfffff000); 165 } 166 167 static int apply_r_riscv_pcrel_lo12_i_rela(struct module *me, void *location, 168 Elf_Addr v) 169 { 170 /* 171 * v is the lo12 value to fill. It is calculated before calling this 172 * handler. 173 */ 174 return riscv_insn_rmw(location, 0xfffff, (v & 0xfff) << 20); 175 } 176 177 static int apply_r_riscv_pcrel_lo12_s_rela(struct module *me, void *location, 178 Elf_Addr v) 179 { 180 /* 181 * v is the lo12 value to fill. It is calculated before calling this 182 * handler. 183 */ 184 u32 imm11_5 = (v & 0xfe0) << (31 - 11); 185 u32 imm4_0 = (v & 0x1f) << (11 - 4); 186 187 return riscv_insn_rmw(location, 0x1fff07f, imm11_5 | imm4_0); 188 } 189 190 static int apply_r_riscv_hi20_rela(struct module *me, void *location, 191 Elf_Addr v) 192 { 193 if (IS_ENABLED(CONFIG_CMODEL_MEDLOW)) { 194 pr_err( 195 "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n", 196 me->name, (long long)v, location); 197 return -EINVAL; 198 } 199 200 return riscv_insn_rmw(location, 0xfff, ((s32)v + 0x800) & 0xfffff000); 201 } 202 203 static int apply_r_riscv_lo12_i_rela(struct module *me, void *location, 204 Elf_Addr v) 205 { 206 /* Skip medlow checking because of filtering by HI20 already */ 207 s32 hi20 = ((s32)v + 0x800) & 0xfffff000; 208 s32 lo12 = ((s32)v - hi20); 209 210 return riscv_insn_rmw(location, 0xfffff, (lo12 & 0xfff) << 20); 211 } 212 213 static int apply_r_riscv_lo12_s_rela(struct module *me, void *location, 214 Elf_Addr v) 215 { 216 /* Skip medlow checking because of filtering by HI20 already */ 217 s32 hi20 = ((s32)v + 0x800) & 0xfffff000; 218 s32 lo12 = ((s32)v - hi20); 219 u32 imm11_5 = (lo12 & 0xfe0) << (31 - 11); 220 u32 imm4_0 = (lo12 & 0x1f) << (11 - 4); 221 222 return riscv_insn_rmw(location, 0x1fff07f, imm11_5 | imm4_0); 223 } 224 225 static int apply_r_riscv_got_hi20_rela(struct module *me, void *location, 226 Elf_Addr v) 227 { 228 ptrdiff_t offset = (void *)v - location; 229 230 /* Always emit the got entry */ 231 if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) { 232 offset = (void *)module_emit_got_entry(me, v) - location; 233 } else { 234 pr_err( 235 "%s: can not generate the GOT entry for symbol = %016llx from PC = %p\n", 236 me->name, (long long)v, location); 237 return -EINVAL; 238 } 239 240 return riscv_insn_rmw(location, 0xfff, (offset + 0x800) & 0xfffff000); 241 } 242 243 static int apply_r_riscv_call_plt_rela(struct module *me, void *location, 244 Elf_Addr v) 245 { 246 ptrdiff_t offset = (void *)v - location; 247 u32 hi20, lo12; 248 249 if (!riscv_insn_valid_32bit_offset(offset)) { 250 /* Only emit the plt entry if offset over 32-bit range */ 251 if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) { 252 offset = (void *)module_emit_plt_entry(me, v) - location; 253 } else { 254 pr_err( 255 "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n", 256 me->name, (long long)v, location); 257 return -EINVAL; 258 } 259 } 260 261 hi20 = (offset + 0x800) & 0xfffff000; 262 lo12 = (offset - hi20) & 0xfff; 263 riscv_insn_rmw(location, 0xfff, hi20); 264 return riscv_insn_rmw(location + 4, 0xfffff, lo12 << 20); 265 } 266 267 static int apply_r_riscv_call_rela(struct module *me, void *location, 268 Elf_Addr v) 269 { 270 ptrdiff_t offset = (void *)v - location; 271 u32 hi20, lo12; 272 273 if (!riscv_insn_valid_32bit_offset(offset)) { 274 pr_err( 275 "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n", 276 me->name, (long long)v, location); 277 return -EINVAL; 278 } 279 280 hi20 = (offset + 0x800) & 0xfffff000; 281 lo12 = (offset - hi20) & 0xfff; 282 riscv_insn_rmw(location, 0xfff, hi20); 283 return riscv_insn_rmw(location + 4, 0xfffff, lo12 << 20); 284 } 285 286 static int apply_r_riscv_relax_rela(struct module *me, void *location, 287 Elf_Addr v) 288 { 289 return 0; 290 } 291 292 static int apply_r_riscv_align_rela(struct module *me, void *location, 293 Elf_Addr v) 294 { 295 pr_err( 296 "%s: The unexpected relocation type 'R_RISCV_ALIGN' from PC = %p\n", 297 me->name, location); 298 return -EINVAL; 299 } 300 301 static int apply_r_riscv_add8_rela(struct module *me, void *location, Elf_Addr v) 302 { 303 *(u8 *)location += (u8)v; 304 return 0; 305 } 306 307 static int apply_r_riscv_add16_rela(struct module *me, void *location, 308 Elf_Addr v) 309 { 310 *(u16 *)location += (u16)v; 311 return 0; 312 } 313 314 static int apply_r_riscv_add32_rela(struct module *me, void *location, 315 Elf_Addr v) 316 { 317 *(u32 *)location += (u32)v; 318 return 0; 319 } 320 321 static int apply_r_riscv_add64_rela(struct module *me, void *location, 322 Elf_Addr v) 323 { 324 *(u64 *)location += (u64)v; 325 return 0; 326 } 327 328 static int apply_r_riscv_sub8_rela(struct module *me, void *location, Elf_Addr v) 329 { 330 *(u8 *)location -= (u8)v; 331 return 0; 332 } 333 334 static int apply_r_riscv_sub16_rela(struct module *me, void *location, 335 Elf_Addr v) 336 { 337 *(u16 *)location -= (u16)v; 338 return 0; 339 } 340 341 static int apply_r_riscv_sub32_rela(struct module *me, void *location, 342 Elf_Addr v) 343 { 344 *(u32 *)location -= (u32)v; 345 return 0; 346 } 347 348 static int apply_r_riscv_sub64_rela(struct module *me, void *location, 349 Elf_Addr v) 350 { 351 *(u64 *)location -= (u64)v; 352 return 0; 353 } 354 355 static int dynamic_linking_not_supported(struct module *me, void *location, 356 Elf_Addr v) 357 { 358 pr_err("%s: Dynamic linking not supported in kernel modules PC = %p\n", 359 me->name, location); 360 return -EINVAL; 361 } 362 363 static int tls_not_supported(struct module *me, void *location, Elf_Addr v) 364 { 365 pr_err("%s: Thread local storage not supported in kernel modules PC = %p\n", 366 me->name, location); 367 return -EINVAL; 368 } 369 370 static int apply_r_riscv_sub6_rela(struct module *me, void *location, Elf_Addr v) 371 { 372 u8 *byte = location; 373 u8 value = v; 374 375 *byte = (*byte - (value & 0x3f)) & 0x3f; 376 return 0; 377 } 378 379 static int apply_r_riscv_set6_rela(struct module *me, void *location, Elf_Addr v) 380 { 381 u8 *byte = location; 382 u8 value = v; 383 384 *byte = (*byte & 0xc0) | (value & 0x3f); 385 return 0; 386 } 387 388 static int apply_r_riscv_set8_rela(struct module *me, void *location, Elf_Addr v) 389 { 390 *(u8 *)location = (u8)v; 391 return 0; 392 } 393 394 static int apply_r_riscv_set16_rela(struct module *me, void *location, 395 Elf_Addr v) 396 { 397 *(u16 *)location = (u16)v; 398 return 0; 399 } 400 401 static int apply_r_riscv_set32_rela(struct module *me, void *location, 402 Elf_Addr v) 403 { 404 *(u32 *)location = (u32)v; 405 return 0; 406 } 407 408 static int apply_r_riscv_32_pcrel_rela(struct module *me, void *location, 409 Elf_Addr v) 410 { 411 *(u32 *)location = v - (uintptr_t)location; 412 return 0; 413 } 414 415 static int apply_r_riscv_plt32_rela(struct module *me, void *location, 416 Elf_Addr v) 417 { 418 ptrdiff_t offset = (void *)v - location; 419 420 if (!riscv_insn_valid_32bit_offset(offset)) { 421 /* Only emit the plt entry if offset over 32-bit range */ 422 if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) { 423 offset = (void *)module_emit_plt_entry(me, v) - location; 424 } else { 425 pr_err("%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n", 426 me->name, (long long)v, location); 427 return -EINVAL; 428 } 429 } 430 431 *(u32 *)location = (u32)offset; 432 return 0; 433 } 434 435 static int apply_r_riscv_set_uleb128(struct module *me, void *location, Elf_Addr v) 436 { 437 *(long *)location = v; 438 return 0; 439 } 440 441 static int apply_r_riscv_sub_uleb128(struct module *me, void *location, Elf_Addr v) 442 { 443 *(long *)location -= v; 444 return 0; 445 } 446 447 static int apply_6_bit_accumulation(struct module *me, void *location, long buffer) 448 { 449 u8 *byte = location; 450 u8 value = buffer; 451 452 if (buffer > 0x3f) { 453 pr_err("%s: value %ld out of range for 6-bit relocation.\n", 454 me->name, buffer); 455 return -EINVAL; 456 } 457 458 *byte = (*byte & 0xc0) | (value & 0x3f); 459 return 0; 460 } 461 462 static int apply_8_bit_accumulation(struct module *me, void *location, long buffer) 463 { 464 if (buffer > U8_MAX) { 465 pr_err("%s: value %ld out of range for 8-bit relocation.\n", 466 me->name, buffer); 467 return -EINVAL; 468 } 469 *(u8 *)location = (u8)buffer; 470 return 0; 471 } 472 473 static int apply_16_bit_accumulation(struct module *me, void *location, long buffer) 474 { 475 if (buffer > U16_MAX) { 476 pr_err("%s: value %ld out of range for 16-bit relocation.\n", 477 me->name, buffer); 478 return -EINVAL; 479 } 480 *(u16 *)location = (u16)buffer; 481 return 0; 482 } 483 484 static int apply_32_bit_accumulation(struct module *me, void *location, long buffer) 485 { 486 if (buffer > U32_MAX) { 487 pr_err("%s: value %ld out of range for 32-bit relocation.\n", 488 me->name, buffer); 489 return -EINVAL; 490 } 491 *(u32 *)location = (u32)buffer; 492 return 0; 493 } 494 495 static int apply_64_bit_accumulation(struct module *me, void *location, long buffer) 496 { 497 *(u64 *)location = (u64)buffer; 498 return 0; 499 } 500 501 static int apply_uleb128_accumulation(struct module *me, void *location, long buffer) 502 { 503 /* 504 * ULEB128 is a variable length encoding. Encode the buffer into 505 * the ULEB128 data format. 506 */ 507 u8 *p = location; 508 509 while (buffer != 0) { 510 u8 value = buffer & 0x7f; 511 512 buffer >>= 7; 513 value |= (!!buffer) << 7; 514 515 *p++ = value; 516 } 517 return 0; 518 } 519 520 /* 521 * Relocations defined in the riscv-elf-psabi-doc. 522 * This handles static linking only. 523 */ 524 static const struct relocation_handlers reloc_handlers[] = { 525 [R_RISCV_32] = { .reloc_handler = apply_r_riscv_32_rela }, 526 [R_RISCV_64] = { .reloc_handler = apply_r_riscv_64_rela }, 527 [R_RISCV_RELATIVE] = { .reloc_handler = dynamic_linking_not_supported }, 528 [R_RISCV_COPY] = { .reloc_handler = dynamic_linking_not_supported }, 529 [R_RISCV_JUMP_SLOT] = { .reloc_handler = dynamic_linking_not_supported }, 530 [R_RISCV_TLS_DTPMOD32] = { .reloc_handler = dynamic_linking_not_supported }, 531 [R_RISCV_TLS_DTPMOD64] = { .reloc_handler = dynamic_linking_not_supported }, 532 [R_RISCV_TLS_DTPREL32] = { .reloc_handler = dynamic_linking_not_supported }, 533 [R_RISCV_TLS_DTPREL64] = { .reloc_handler = dynamic_linking_not_supported }, 534 [R_RISCV_TLS_TPREL32] = { .reloc_handler = dynamic_linking_not_supported }, 535 [R_RISCV_TLS_TPREL64] = { .reloc_handler = dynamic_linking_not_supported }, 536 /* 12-15 undefined */ 537 [R_RISCV_BRANCH] = { .reloc_handler = apply_r_riscv_branch_rela }, 538 [R_RISCV_JAL] = { .reloc_handler = apply_r_riscv_jal_rela }, 539 [R_RISCV_CALL] = { .reloc_handler = apply_r_riscv_call_rela }, 540 [R_RISCV_CALL_PLT] = { .reloc_handler = apply_r_riscv_call_plt_rela }, 541 [R_RISCV_GOT_HI20] = { .reloc_handler = apply_r_riscv_got_hi20_rela }, 542 [R_RISCV_TLS_GOT_HI20] = { .reloc_handler = tls_not_supported }, 543 [R_RISCV_TLS_GD_HI20] = { .reloc_handler = tls_not_supported }, 544 [R_RISCV_PCREL_HI20] = { .reloc_handler = apply_r_riscv_pcrel_hi20_rela }, 545 [R_RISCV_PCREL_LO12_I] = { .reloc_handler = apply_r_riscv_pcrel_lo12_i_rela }, 546 [R_RISCV_PCREL_LO12_S] = { .reloc_handler = apply_r_riscv_pcrel_lo12_s_rela }, 547 [R_RISCV_HI20] = { .reloc_handler = apply_r_riscv_hi20_rela }, 548 [R_RISCV_LO12_I] = { .reloc_handler = apply_r_riscv_lo12_i_rela }, 549 [R_RISCV_LO12_S] = { .reloc_handler = apply_r_riscv_lo12_s_rela }, 550 [R_RISCV_TPREL_HI20] = { .reloc_handler = tls_not_supported }, 551 [R_RISCV_TPREL_LO12_I] = { .reloc_handler = tls_not_supported }, 552 [R_RISCV_TPREL_LO12_S] = { .reloc_handler = tls_not_supported }, 553 [R_RISCV_TPREL_ADD] = { .reloc_handler = tls_not_supported }, 554 [R_RISCV_ADD8] = { .reloc_handler = apply_r_riscv_add8_rela, 555 .accumulate_handler = apply_8_bit_accumulation }, 556 [R_RISCV_ADD16] = { .reloc_handler = apply_r_riscv_add16_rela, 557 .accumulate_handler = apply_16_bit_accumulation }, 558 [R_RISCV_ADD32] = { .reloc_handler = apply_r_riscv_add32_rela, 559 .accumulate_handler = apply_32_bit_accumulation }, 560 [R_RISCV_ADD64] = { .reloc_handler = apply_r_riscv_add64_rela, 561 .accumulate_handler = apply_64_bit_accumulation }, 562 [R_RISCV_SUB8] = { .reloc_handler = apply_r_riscv_sub8_rela, 563 .accumulate_handler = apply_8_bit_accumulation }, 564 [R_RISCV_SUB16] = { .reloc_handler = apply_r_riscv_sub16_rela, 565 .accumulate_handler = apply_16_bit_accumulation }, 566 [R_RISCV_SUB32] = { .reloc_handler = apply_r_riscv_sub32_rela, 567 .accumulate_handler = apply_32_bit_accumulation }, 568 [R_RISCV_SUB64] = { .reloc_handler = apply_r_riscv_sub64_rela, 569 .accumulate_handler = apply_64_bit_accumulation }, 570 /* 41-42 reserved for future standard use */ 571 [R_RISCV_ALIGN] = { .reloc_handler = apply_r_riscv_align_rela }, 572 [R_RISCV_RVC_BRANCH] = { .reloc_handler = apply_r_riscv_rvc_branch_rela }, 573 [R_RISCV_RVC_JUMP] = { .reloc_handler = apply_r_riscv_rvc_jump_rela }, 574 /* 46-50 reserved for future standard use */ 575 [R_RISCV_RELAX] = { .reloc_handler = apply_r_riscv_relax_rela }, 576 [R_RISCV_SUB6] = { .reloc_handler = apply_r_riscv_sub6_rela, 577 .accumulate_handler = apply_6_bit_accumulation }, 578 [R_RISCV_SET6] = { .reloc_handler = apply_r_riscv_set6_rela, 579 .accumulate_handler = apply_6_bit_accumulation }, 580 [R_RISCV_SET8] = { .reloc_handler = apply_r_riscv_set8_rela, 581 .accumulate_handler = apply_8_bit_accumulation }, 582 [R_RISCV_SET16] = { .reloc_handler = apply_r_riscv_set16_rela, 583 .accumulate_handler = apply_16_bit_accumulation }, 584 [R_RISCV_SET32] = { .reloc_handler = apply_r_riscv_set32_rela, 585 .accumulate_handler = apply_32_bit_accumulation }, 586 [R_RISCV_32_PCREL] = { .reloc_handler = apply_r_riscv_32_pcrel_rela }, 587 [R_RISCV_IRELATIVE] = { .reloc_handler = dynamic_linking_not_supported }, 588 [R_RISCV_PLT32] = { .reloc_handler = apply_r_riscv_plt32_rela }, 589 [R_RISCV_SET_ULEB128] = { .reloc_handler = apply_r_riscv_set_uleb128, 590 .accumulate_handler = apply_uleb128_accumulation }, 591 [R_RISCV_SUB_ULEB128] = { .reloc_handler = apply_r_riscv_sub_uleb128, 592 .accumulate_handler = apply_uleb128_accumulation }, 593 /* 62-191 reserved for future standard use */ 594 /* 192-255 nonstandard ABI extensions */ 595 }; 596 597 static void 598 process_accumulated_relocations(struct module *me, 599 struct hlist_head **relocation_hashtable, 600 struct list_head *used_buckets_list) 601 { 602 /* 603 * Only ADD/SUB/SET/ULEB128 should end up here. 604 * 605 * Each bucket may have more than one relocation location. All 606 * relocations for a location are stored in a list in a bucket. 607 * 608 * Relocations are applied to a temp variable before being stored to the 609 * provided location to check for overflow. This also allows ULEB128 to 610 * properly decide how many entries are needed before storing to 611 * location. The final value is stored into location using the handler 612 * for the last relocation to an address. 613 * 614 * Three layers of indexing: 615 * - Each of the buckets in use 616 * - Groups of relocations in each bucket by location address 617 * - Each relocation entry for a location address 618 */ 619 struct used_bucket *bucket_iter; 620 struct used_bucket *bucket_iter_tmp; 621 struct relocation_head *rel_head_iter; 622 struct hlist_node *rel_head_iter_tmp; 623 struct relocation_entry *rel_entry_iter; 624 struct relocation_entry *rel_entry_iter_tmp; 625 int curr_type; 626 void *location; 627 long buffer; 628 629 list_for_each_entry_safe(bucket_iter, bucket_iter_tmp, 630 used_buckets_list, head) { 631 hlist_for_each_entry_safe(rel_head_iter, rel_head_iter_tmp, 632 bucket_iter->bucket, node) { 633 buffer = 0; 634 location = rel_head_iter->location; 635 list_for_each_entry_safe(rel_entry_iter, 636 rel_entry_iter_tmp, 637 rel_head_iter->rel_entry, 638 head) { 639 curr_type = rel_entry_iter->type; 640 reloc_handlers[curr_type].reloc_handler( 641 me, &buffer, rel_entry_iter->value); 642 kfree(rel_entry_iter); 643 } 644 reloc_handlers[curr_type].accumulate_handler( 645 me, location, buffer); 646 kfree(rel_head_iter); 647 } 648 kfree(bucket_iter); 649 } 650 651 kfree(*relocation_hashtable); 652 } 653 654 static int add_relocation_to_accumulate(struct module *me, int type, 655 void *location, 656 unsigned int hashtable_bits, Elf_Addr v, 657 struct hlist_head *relocation_hashtable, 658 struct list_head *used_buckets_list) 659 { 660 struct relocation_entry *entry; 661 struct relocation_head *rel_head; 662 struct hlist_head *current_head; 663 struct used_bucket *bucket; 664 unsigned long hash; 665 666 entry = kmalloc(sizeof(*entry), GFP_KERNEL); 667 668 if (!entry) 669 return -ENOMEM; 670 671 INIT_LIST_HEAD(&entry->head); 672 entry->type = type; 673 entry->value = v; 674 675 hash = hash_min((uintptr_t)location, hashtable_bits); 676 677 current_head = &relocation_hashtable[hash]; 678 679 /* 680 * Search for the relocation_head for the relocations that happen at the 681 * provided location 682 */ 683 bool found = false; 684 struct relocation_head *rel_head_iter; 685 686 hlist_for_each_entry(rel_head_iter, current_head, node) { 687 if (rel_head_iter->location == location) { 688 found = true; 689 rel_head = rel_head_iter; 690 break; 691 } 692 } 693 694 /* 695 * If there has not yet been any relocations at the provided location, 696 * create a relocation_head for that location and populate it with this 697 * relocation_entry. 698 */ 699 if (!found) { 700 rel_head = kmalloc(sizeof(*rel_head), GFP_KERNEL); 701 702 if (!rel_head) { 703 kfree(entry); 704 return -ENOMEM; 705 } 706 707 rel_head->rel_entry = 708 kmalloc(sizeof(struct list_head), GFP_KERNEL); 709 710 if (!rel_head->rel_entry) { 711 kfree(entry); 712 kfree(rel_head); 713 return -ENOMEM; 714 } 715 716 INIT_LIST_HEAD(rel_head->rel_entry); 717 rel_head->location = location; 718 INIT_HLIST_NODE(&rel_head->node); 719 if (!current_head->first) { 720 bucket = 721 kmalloc(sizeof(struct used_bucket), GFP_KERNEL); 722 723 if (!bucket) { 724 kfree(entry); 725 kfree(rel_head->rel_entry); 726 kfree(rel_head); 727 return -ENOMEM; 728 } 729 730 INIT_LIST_HEAD(&bucket->head); 731 bucket->bucket = current_head; 732 list_add(&bucket->head, used_buckets_list); 733 } 734 hlist_add_head(&rel_head->node, current_head); 735 } 736 737 /* Add relocation to head of discovered rel_head */ 738 list_add_tail(&entry->head, rel_head->rel_entry); 739 740 return 0; 741 } 742 743 static unsigned int 744 initialize_relocation_hashtable(unsigned int num_relocations, 745 struct hlist_head **relocation_hashtable) 746 { 747 /* Can safely assume that bits is not greater than sizeof(long) */ 748 unsigned long hashtable_size = roundup_pow_of_two(num_relocations); 749 /* 750 * When hashtable_size == 1, hashtable_bits == 0. 751 * This is valid because the hashing algorithm returns 0 in this case. 752 */ 753 unsigned int hashtable_bits = ilog2(hashtable_size); 754 755 /* 756 * Double size of hashtable if num_relocations * 1.25 is greater than 757 * hashtable_size. 758 */ 759 int should_double_size = ((num_relocations + (num_relocations >> 2)) > (hashtable_size)); 760 761 hashtable_bits += should_double_size; 762 763 hashtable_size <<= should_double_size; 764 765 *relocation_hashtable = kmalloc_array(hashtable_size, 766 sizeof(**relocation_hashtable), 767 GFP_KERNEL); 768 if (!*relocation_hashtable) 769 return 0; 770 771 __hash_init(*relocation_hashtable, hashtable_size); 772 773 return hashtable_bits; 774 } 775 776 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, 777 unsigned int symindex, unsigned int relsec, 778 struct module *me) 779 { 780 Elf_Rela *rel = (void *) sechdrs[relsec].sh_addr; 781 int (*handler)(struct module *me, void *location, Elf_Addr v); 782 Elf_Sym *sym; 783 void *location; 784 unsigned int i, type; 785 unsigned int j_idx = 0; 786 Elf_Addr v; 787 int res; 788 unsigned int num_relocations = sechdrs[relsec].sh_size / sizeof(*rel); 789 struct hlist_head *relocation_hashtable; 790 struct list_head used_buckets_list; 791 unsigned int hashtable_bits; 792 793 hashtable_bits = initialize_relocation_hashtable(num_relocations, 794 &relocation_hashtable); 795 796 if (!relocation_hashtable) 797 return -ENOMEM; 798 799 INIT_LIST_HEAD(&used_buckets_list); 800 801 pr_debug("Applying relocate section %u to %u\n", relsec, 802 sechdrs[relsec].sh_info); 803 804 for (i = 0; i < num_relocations; i++) { 805 /* This is where to make the change */ 806 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 807 + rel[i].r_offset; 808 /* This is the symbol it is referring to */ 809 sym = (Elf_Sym *)sechdrs[symindex].sh_addr 810 + ELF_RISCV_R_SYM(rel[i].r_info); 811 if (IS_ERR_VALUE(sym->st_value)) { 812 /* Ignore unresolved weak symbol */ 813 if (ELF_ST_BIND(sym->st_info) == STB_WEAK) 814 continue; 815 pr_warn("%s: Unknown symbol %s\n", 816 me->name, strtab + sym->st_name); 817 return -ENOENT; 818 } 819 820 type = ELF_RISCV_R_TYPE(rel[i].r_info); 821 822 if (type < ARRAY_SIZE(reloc_handlers)) 823 handler = reloc_handlers[type].reloc_handler; 824 else 825 handler = NULL; 826 827 if (!handler) { 828 pr_err("%s: Unknown relocation type %u\n", 829 me->name, type); 830 return -EINVAL; 831 } 832 833 v = sym->st_value + rel[i].r_addend; 834 835 if (type == R_RISCV_PCREL_LO12_I || type == R_RISCV_PCREL_LO12_S) { 836 unsigned int j = j_idx; 837 bool found = false; 838 839 do { 840 unsigned long hi20_loc = 841 sechdrs[sechdrs[relsec].sh_info].sh_addr 842 + rel[j].r_offset; 843 u32 hi20_type = ELF_RISCV_R_TYPE(rel[j].r_info); 844 845 /* Find the corresponding HI20 relocation entry */ 846 if (hi20_loc == sym->st_value 847 && (hi20_type == R_RISCV_PCREL_HI20 848 || hi20_type == R_RISCV_GOT_HI20)) { 849 s32 hi20, lo12; 850 Elf_Sym *hi20_sym = 851 (Elf_Sym *)sechdrs[symindex].sh_addr 852 + ELF_RISCV_R_SYM(rel[j].r_info); 853 unsigned long hi20_sym_val = 854 hi20_sym->st_value 855 + rel[j].r_addend; 856 857 /* Calculate lo12 */ 858 size_t offset = hi20_sym_val - hi20_loc; 859 if (IS_ENABLED(CONFIG_MODULE_SECTIONS) 860 && hi20_type == R_RISCV_GOT_HI20) { 861 offset = module_emit_got_entry( 862 me, hi20_sym_val); 863 offset = offset - hi20_loc; 864 } 865 hi20 = (offset + 0x800) & 0xfffff000; 866 lo12 = offset - hi20; 867 v = lo12; 868 found = true; 869 870 break; 871 } 872 873 j++; 874 if (j > sechdrs[relsec].sh_size / sizeof(*rel)) 875 j = 0; 876 877 } while (j_idx != j); 878 879 if (!found) { 880 pr_err( 881 "%s: Can not find HI20 relocation information\n", 882 me->name); 883 return -EINVAL; 884 } 885 886 /* Record the previous j-loop end index */ 887 j_idx = j; 888 } 889 890 if (reloc_handlers[type].accumulate_handler) 891 res = add_relocation_to_accumulate(me, type, location, 892 hashtable_bits, v, 893 relocation_hashtable, 894 &used_buckets_list); 895 else 896 res = handler(me, location, v); 897 if (res) 898 return res; 899 } 900 901 process_accumulated_relocations(me, &relocation_hashtable, 902 &used_buckets_list); 903 904 return 0; 905 } 906 907 int module_finalize(const Elf_Ehdr *hdr, 908 const Elf_Shdr *sechdrs, 909 struct module *me) 910 { 911 const Elf_Shdr *s; 912 913 s = find_section(hdr, sechdrs, ".alternative"); 914 if (s) 915 apply_module_alternatives((void *)s->sh_addr, s->sh_size); 916 917 return 0; 918 } 919