arch/arm/kernel/module.c

   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/vmalloc.h>
  16 #include <linux/fs.h>
  17 #include <linux/string.h>
  18 #include <linux/gfp.h>
  19
  20 #include <asm/sections.h>
  21 #include <asm/smp_plat.h>
  22 #include <asm/unwind.h>
  23 #include <asm/opcodes.h>
  24
  25 #ifdef CONFIG_XIP_KERNEL
  26 /*
  27  * The XIP kernel text is mapped in the module area for modules and
  28  * some other stuff to work without any indirect relocations.
  29  * MODULES_VADDR is redefined here and not in asm/memory.h to avoid
  30  * recompiling the whole kernel when CONFIG_XIP_KERNEL is turned on/off.
  31  */
  32 #undef MODULES_VADDR
  33 #define MODULES_VADDR   (((unsigned long)_exiprom + ~PMD_MASK) & PMD_MASK)
  34 #endif
  35
  36 #ifdef CONFIG_MMU
  37 void *module_alloc(unsigned long size)
  38 {
  39         gfp_t gfp_mask = GFP_KERNEL;
  40         void *p;
  41
  42         /* Silence the initial allocation */
  43         if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS))
  44                 gfp_mask |= __GFP_NOWARN;
  45
  46         p = __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
  47                                 gfp_mask, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
  48                                 __builtin_return_address(0));
  49         if (!IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || p)
  50                 return p;
  51         return __vmalloc_node_range(size, 1,  VMALLOC_START, VMALLOC_END,
  52                                 GFP_KERNEL, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
  53                                 __builtin_return_address(0));
  54 }
  55 #endif
  56
  57 bool module_init_section(const char *name)
  58 {
  59         return strstarts(name, ".init") ||
  60                 strstarts(name, ".ARM.extab.init") ||
  61                 strstarts(name, ".ARM.exidx.init");
  62 }
  63
  64 bool module_exit_section(const char *name)
  65 {
  66         return strstarts(name, ".exit") ||
  67                 strstarts(name, ".ARM.extab.exit") ||
  68                 strstarts(name, ".ARM.exidx.exit");
  69 }
  70
  71 #ifdef CONFIG_ARM_HAS_GROUP_RELOCS
  72 /*
  73  * This implements the partitioning algorithm for group relocations as
  74  * documented in the ARM AArch32 ELF psABI (IHI 0044).
  75  *
  76  * A single PC-relative symbol reference is divided in up to 3 add or subtract
  77  * operations, where the final one could be incorporated into a load/store
  78  * instruction with immediate offset. E.g.,
  79  *
  80  *   ADD        Rd, PC, #...            or      ADD     Rd, PC, #...
  81  *   ADD        Rd, Rd, #...                    ADD     Rd, Rd, #...
  82  *   LDR        Rd, [Rd, #...]                  ADD     Rd, Rd, #...
  83  *
  84  * The latter has a guaranteed range of only 16 MiB (3x8 == 24 bits), so it is
  85  * of limited use in the kernel. However, the ADD/ADD/LDR combo has a range of
  86  * -/+ 256 MiB, (2x8 + 12 == 28 bits), which means it has sufficient range for
  87  * any in-kernel symbol reference (unless module PLTs are being used).
  88  *
  89  * The main advantage of this approach over the typical pattern using a literal
  90  * load is that literal loads may miss in the D-cache, and generally lead to
  91  * lower cache efficiency for variables that are referenced often from many
  92  * different places in the code.
  93  */
  94 static u32 get_group_rem(u32 group, u32 *offset)
  95 {
  96         u32 val = *offset;
  97         u32 shift;
  98         do {
  99                 shift = val ? (31 - __fls(val)) & ~1 : 32;
 100                 *offset = val;
 101                 if (!val)
 102                         break;
 103                 val &= 0xffffff >> shift;
 104         } while (group--);
 105         return shift;
 106 }
 107 #endif
 108
 109 int
 110 apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
 111                unsigned int relindex, struct module *module)
 112 {
 113         Elf32_Shdr *symsec = sechdrs + symindex;
 114         Elf32_Shdr *relsec = sechdrs + relindex;
 115         Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
 116         Elf32_Rel *rel = (void *)relsec->sh_addr;
 117         unsigned int i;
 118
 119         for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++, rel++) {
 120                 unsigned long loc;
 121                 Elf32_Sym *sym;
 122                 const char *symname;
 123 #ifdef CONFIG_ARM_HAS_GROUP_RELOCS
 124                 u32 shift, group = 1;
 125 #endif
 126                 s32 offset;
 127                 u32 tmp;
 128 #ifdef CONFIG_THUMB2_KERNEL
 129                 u32 upper, lower, sign, j1, j2;
 130 #endif
 131
 132                 offset = ELF32_R_SYM(rel->r_info);
 133                 if (offset < 0 || offset > (symsec->sh_size / sizeof(Elf32_Sym))) {
 134                         pr_err("%s: section %u reloc %u: bad relocation sym offset\n",
 135                                 module->name, relindex, i);
 136                         return -ENOEXEC;
 137                 }
 138
 139                 sym = ((Elf32_Sym *)symsec->sh_addr) + offset;
 140                 symname = strtab + sym->st_name;
 141
 142                 if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(u32)) {
 143                         pr_err("%s: section %u reloc %u sym '%s': out of bounds relocation, offset %d size %u\n",
 144                                module->name, relindex, i, symname,
 145                                rel->r_offset, dstsec->sh_size);
 146                         return -ENOEXEC;
 147                 }
 148
 149                 loc = dstsec->sh_addr + rel->r_offset;
 150
 151                 switch (ELF32_R_TYPE(rel->r_info)) {
 152                 case R_ARM_NONE:
 153                         /* ignore */
 154                         break;
 155
 156                 case R_ARM_ABS32:
 157                 case R_ARM_TARGET1:
 158                         *(u32 *)loc += sym->st_value;
 159                         break;
 160
 161                 case R_ARM_PC24:
 162                 case R_ARM_CALL:
 163                 case R_ARM_JUMP24:
 164                         if (sym->st_value & 3) {
 165                                 pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (ARM -> Thumb)\n",
 166                                        module->name, relindex, i, symname);
 167                                 return -ENOEXEC;
 168                         }
 169
 170                         offset = __mem_to_opcode_arm(*(u32 *)loc);
 171                         offset = (offset & 0x00ffffff) << 2;
 172                         offset = sign_extend32(offset, 25);
 173
 174                         offset += sym->st_value - loc;
 175
 176                         /*
 177                          * Route through a PLT entry if 'offset' exceeds the
 178                          * supported range. Note that 'offset + loc + 8'
 179                          * contains the absolute jump target, i.e.,
 180                          * @sym + addend, corrected for the +8 PC bias.
 181                          */
 182                         if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) &&
 183                             (offset <= (s32)0xfe000000 ||
 184                              offset >= (s32)0x02000000))
 185                                 offset = get_module_plt(module, loc,
 186                                                         offset + loc + 8)
 187                                          - loc - 8;
 188
 189                         if (offset <= (s32)0xfe000000 ||
 190                             offset >= (s32)0x02000000) {
 191                                 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
 192                                        module->name, relindex, i, symname,
 193                                        ELF32_R_TYPE(rel->r_info), loc,
 194                                        sym->st_value);
 195                                 return -ENOEXEC;
 196                         }
 197
 198                         offset >>= 2;
 199                         offset &= 0x00ffffff;
 200
 201                         *(u32 *)loc &= __opcode_to_mem_arm(0xff000000);
 202                         *(u32 *)loc |= __opcode_to_mem_arm(offset);
 203                         break;
 204
 205                case R_ARM_V4BX:
 206                        /* Preserve Rm and the condition code. Alter
 207                         * other bits to re-code instruction as
 208                         * MOV PC,Rm.
 209                         */
 210                        *(u32 *)loc &= __opcode_to_mem_arm(0xf000000f);
 211                        *(u32 *)loc |= __opcode_to_mem_arm(0x01a0f000);
 212                        break;
 213
 214                 case R_ARM_PREL31:
 215                         offset = (*(s32 *)loc << 1) >> 1; /* sign extend */
 216                         offset += sym->st_value - loc;
 217                         if (offset >= 0x40000000 || offset < -0x40000000) {
 218                                 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
 219                                        module->name, relindex, i, symname,
 220                                        ELF32_R_TYPE(rel->r_info), loc,
 221                                        sym->st_value);
 222                                 return -ENOEXEC;
 223                         }
 224                         *(u32 *)loc &= 0x80000000;
 225                         *(u32 *)loc |= offset & 0x7fffffff;
 226                         break;
 227
 228                 case R_ARM_REL32:
 229                         *(u32 *)loc += sym->st_value - loc;
 230                         break;
 231
 232                 case R_ARM_MOVW_ABS_NC:
 233                 case R_ARM_MOVT_ABS:
 234                 case R_ARM_MOVW_PREL_NC:
 235                 case R_ARM_MOVT_PREL:
 236                         offset = tmp = __mem_to_opcode_arm(*(u32 *)loc);
 237                         offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
 238                         offset = sign_extend32(offset, 15);
 239
 240                         offset += sym->st_value;
 241                         if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_PREL ||
 242                             ELF32_R_TYPE(rel->r_info) == R_ARM_MOVW_PREL_NC)
 243                                 offset -= loc;
 244                         if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS ||
 245                             ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_PREL)
 246                                 offset >>= 16;
 247
 248                         tmp &= 0xfff0f000;
 249                         tmp |= ((offset & 0xf000) << 4) |
 250                                 (offset & 0x0fff);
 251
 252                         *(u32 *)loc = __opcode_to_mem_arm(tmp);
 253                         break;
 254
 255 #ifdef CONFIG_ARM_HAS_GROUP_RELOCS
 256                 case R_ARM_ALU_PC_G0_NC:
 257                         group = 0;
 258                         fallthrough;
 259                 case R_ARM_ALU_PC_G1_NC:
 260                         tmp = __mem_to_opcode_arm(*(u32 *)loc);
 261                         offset = ror32(tmp & 0xff, (tmp & 0xf00) >> 7);
 262                         if (tmp & BIT(22))
 263                                 offset = -offset;
 264                         offset += sym->st_value - loc;
 265                         if (offset < 0) {
 266                                 offset = -offset;
 267                                 tmp = (tmp & ~BIT(23)) | BIT(22); // SUB opcode
 268                         } else {
 269                                 tmp = (tmp & ~BIT(22)) | BIT(23); // ADD opcode
 270                         }
 271
 272                         shift = get_group_rem(group, &offset);
 273                         if (shift < 24) {
 274                                 offset >>= 24 - shift;
 275                                 offset |= (shift + 8) << 7;
 276                         }
 277                         *(u32 *)loc = __opcode_to_mem_arm((tmp & ~0xfff) | offset);
 278                         break;
 279
 280                 case R_ARM_LDR_PC_G2:
 281                         tmp = __mem_to_opcode_arm(*(u32 *)loc);
 282                         offset = tmp & 0xfff;
 283                         if (~tmp & BIT(23))             // U bit cleared?
 284                                 offset = -offset;
 285                         offset += sym->st_value - loc;
 286                         if (offset < 0) {
 287                                 offset = -offset;
 288                                 tmp &= ~BIT(23);        // clear U bit
 289                         } else {
 290                                 tmp |= BIT(23);         // set U bit
 291                         }
 292                         get_group_rem(2, &offset);
 293
 294                         if (offset > 0xfff) {
 295                                 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
 296                                        module->name, relindex, i, symname,
 297                                        ELF32_R_TYPE(rel->r_info), loc,
 298                                        sym->st_value);
 299                                 return -ENOEXEC;
 300                         }
 301                         *(u32 *)loc = __opcode_to_mem_arm((tmp & ~0xfff) | offset);
 302                         break;
 303 #endif
 304 #ifdef CONFIG_THUMB2_KERNEL
 305                 case R_ARM_THM_CALL:
 306                 case R_ARM_THM_JUMP24:
 307                         /*
 308                          * For function symbols, only Thumb addresses are
 309                          * allowed (no interworking).
 310                          *
 311                          * For non-function symbols, the destination
 312                          * has no specific ARM/Thumb disposition, so
 313                          * the branch is resolved under the assumption
 314                          * that interworking is not required.
 315                          */
 316                         if (ELF32_ST_TYPE(sym->st_info) == STT_FUNC &&
 317                             !(sym->st_value & 1)) {
 318                                 pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (Thumb -> ARM)\n",
 319                                        module->name, relindex, i, symname);
 320                                 return -ENOEXEC;
 321                         }
 322
 323                         upper = __mem_to_opcode_thumb16(*(u16 *)loc);
 324                         lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));
 325
 326                         /*
 327                          * 25 bit signed address range (Thumb-2 BL and B.W
 328                          * instructions):
 329                          *   S:I1:I2:imm10:imm11:0
 330                          * where:
 331                          *   S     = upper[10]   = offset[24]
 332                          *   I1    = ~(J1 ^ S)   = offset[23]
 333                          *   I2    = ~(J2 ^ S)   = offset[22]
 334                          *   imm10 = upper[9:0]  = offset[21:12]
 335                          *   imm11 = lower[10:0] = offset[11:1]
 336                          *   J1    = lower[13]
 337                          *   J2    = lower[11]
 338                          */
 339                         sign = (upper >> 10) & 1;
 340                         j1 = (lower >> 13) & 1;
 341                         j2 = (lower >> 11) & 1;
 342                         offset = (sign << 24) | ((~(j1 ^ sign) & 1) << 23) |
 343                                 ((~(j2 ^ sign) & 1) << 22) |
 344                                 ((upper & 0x03ff) << 12) |
 345                                 ((lower & 0x07ff) << 1);
 346                         offset = sign_extend32(offset, 24);
 347                         offset += sym->st_value - loc;
 348
 349                         /*
 350                          * Route through a PLT entry if 'offset' exceeds the
 351                          * supported range.
 352                          */
 353                         if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) &&
 354                             (offset <= (s32)0xff000000 ||
 355                              offset >= (s32)0x01000000))
 356                                 offset = get_module_plt(module, loc,
 357                                                         offset + loc + 4)
 358                                          - loc - 4;
 359
 360                         if (offset <= (s32)0xff000000 ||
 361                             offset >= (s32)0x01000000) {
 362                                 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
 363                                        module->name, relindex, i, symname,
 364                                        ELF32_R_TYPE(rel->r_info), loc,
 365                                        sym->st_value);
 366                                 return -ENOEXEC;
 367                         }
 368
 369                         sign = (offset >> 24) & 1;
 370                         j1 = sign ^ (~(offset >> 23) & 1);
 371                         j2 = sign ^ (~(offset >> 22) & 1);
 372                         upper = (u16)((upper & 0xf800) | (sign << 10) |
 373                                             ((offset >> 12) & 0x03ff));
 374                         lower = (u16)((lower & 0xd000) |
 375                                       (j1 << 13) | (j2 << 11) |
 376                                       ((offset >> 1) & 0x07ff));
 377
 378                         *(u16 *)loc = __opcode_to_mem_thumb16(upper);
 379                         *(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
 380                         break;
 381
 382                 case R_ARM_THM_MOVW_ABS_NC:
 383                 case R_ARM_THM_MOVT_ABS:
 384                 case R_ARM_THM_MOVW_PREL_NC:
 385                 case R_ARM_THM_MOVT_PREL:
 386                         upper = __mem_to_opcode_thumb16(*(u16 *)loc);
 387                         lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));
 388
 389                         /*
 390                          * MOVT/MOVW instructions encoding in Thumb-2:
 391                          *
 392                          * i    = upper[10]
 393                          * imm4 = upper[3:0]
 394                          * imm3 = lower[14:12]
 395                          * imm8 = lower[7:0]
 396                          *
 397                          * imm16 = imm4:i:imm3:imm8
 398                          */
 399                         offset = ((upper & 0x000f) << 12) |
 400                                 ((upper & 0x0400) << 1) |
 401                                 ((lower & 0x7000) >> 4) | (lower & 0x00ff);
 402                         offset = sign_extend32(offset, 15);
 403                         offset += sym->st_value;
 404
 405                         if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_PREL ||
 406                             ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVW_PREL_NC)
 407                                 offset -= loc;
 408                         if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS ||
 409                             ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_PREL)
 410                                 offset >>= 16;
 411
 412                         upper = (u16)((upper & 0xfbf0) |
 413                                       ((offset & 0xf000) >> 12) |
 414                                       ((offset & 0x0800) >> 1));
 415                         lower = (u16)((lower & 0x8f00) |
 416                                       ((offset & 0x0700) << 4) |
 417                                       (offset & 0x00ff));
 418                         *(u16 *)loc = __opcode_to_mem_thumb16(upper);
 419                         *(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
 420                         break;
 421 #endif
 422
 423                 default:
 424                         pr_err("%s: unknown relocation: %u\n",
 425                                module->name, ELF32_R_TYPE(rel->r_info));
 426                         return -ENOEXEC;
 427                 }
 428         }
 429         return 0;
 430 }
 431
 432 struct mod_unwind_map {
 433         const Elf_Shdr *unw_sec;
 434         const Elf_Shdr *txt_sec;
 435 };
 436
 437 static const Elf_Shdr *find_mod_section(const Elf32_Ehdr *hdr,
 438         const Elf_Shdr *sechdrs, const char *name)
 439 {
 440         const Elf_Shdr *s, *se;
 441         const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 442
 443         for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++)
 444                 if (strcmp(name, secstrs + s->sh_name) == 0)
 445                         return s;
 446
 447         return NULL;
 448 }
 449
 450 extern void fixup_pv_table(const void *, unsigned long);
 451 extern void fixup_smp(const void *, unsigned long);
 452
 453 int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
 454                     struct module *mod)
 455 {
 456         const Elf_Shdr *s = NULL;
 457 #ifdef CONFIG_ARM_UNWIND
 458         const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 459         const Elf_Shdr *sechdrs_end = sechdrs + hdr->e_shnum;
 460         struct list_head *unwind_list = &mod->arch.unwind_list;
 461
 462         INIT_LIST_HEAD(unwind_list);
 463         mod->arch.init_table = NULL;
 464
 465         for (s = sechdrs; s < sechdrs_end; s++) {
 466                 const char *secname = secstrs + s->sh_name;
 467                 const char *txtname;
 468                 const Elf_Shdr *txt_sec;
 469
 470                 if (!(s->sh_flags & SHF_ALLOC) ||
 471                     s->sh_type != ELF_SECTION_UNWIND)
 472                         continue;
 473
 474                 if (!strcmp(".ARM.exidx", secname))
 475                         txtname = ".text";
 476                 else
 477                         txtname = secname + strlen(".ARM.exidx");
 478                 txt_sec = find_mod_section(hdr, sechdrs, txtname);
 479
 480                 if (txt_sec) {
 481                         struct unwind_table *table =
 482                                 unwind_table_add(s->sh_addr,
 483                                                 s->sh_size,
 484                                                 txt_sec->sh_addr,
 485                                                 txt_sec->sh_size);
 486
 487                         list_add(&table->mod_list, unwind_list);
 488
 489                         /* save init table for module_arch_freeing_init */
 490                         if (strcmp(".ARM.exidx.init.text", secname) == 0)
 491                                 mod->arch.init_table = table;
 492                 }
 493         }
 494 #endif
 495 #ifdef CONFIG_ARM_PATCH_PHYS_VIRT
 496         s = find_mod_section(hdr, sechdrs, ".pv_table");
 497         if (s)
 498                 fixup_pv_table((void *)s->sh_addr, s->sh_size);
 499 #endif
 500         s = find_mod_section(hdr, sechdrs, ".alt.smp.init");
 501         if (s && !is_smp())
 502 #ifdef CONFIG_SMP_ON_UP
 503                 fixup_smp((void *)s->sh_addr, s->sh_size);
 504 #else
 505                 return -EINVAL;
 506 #endif
 507         return 0;
 508 }
 509
 510 void
 511 module_arch_cleanup(struct module *mod)
 512 {
 513 #ifdef CONFIG_ARM_UNWIND
 514         struct unwind_table *tmp;
 515         struct unwind_table *n;
 516
 517         list_for_each_entry_safe(tmp, n,
 518                         &mod->arch.unwind_list, mod_list) {
 519                 list_del(&tmp->mod_list);
 520                 unwind_table_del(tmp);
 521         }
 522         mod->arch.init_table = NULL;
 523 #endif
 524 }
 525
 526 void __weak module_arch_freeing_init(struct module *mod)
 527 {
 528 #ifdef CONFIG_ARM_UNWIND
 529         struct unwind_table *init = mod->arch.init_table;
 530
 531         if (init) {
 532                 mod->arch.init_table = NULL;
 533                 list_del(&init->mod_list);
 534                 unwind_table_del(init);
 535         }
 536 #endif
 537 }