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 int
  72 apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
  73                unsigned int relindex, struct module *module)
  74 {
  75         Elf32_Shdr *symsec = sechdrs + symindex;
  76         Elf32_Shdr *relsec = sechdrs + relindex;
  77         Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
  78         Elf32_Rel *rel = (void *)relsec->sh_addr;
  79         unsigned int i;
  80
  81         for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++, rel++) {
  82                 unsigned long loc;
  83                 Elf32_Sym *sym;
  84                 const char *symname;
  85                 s32 offset;
  86                 u32 tmp;
  87 #ifdef CONFIG_THUMB2_KERNEL
  88                 u32 upper, lower, sign, j1, j2;
  89 #endif
  90
  91                 offset = ELF32_R_SYM(rel->r_info);
  92                 if (offset < 0 || offset > (symsec->sh_size / sizeof(Elf32_Sym))) {
  93                         pr_err("%s: section %u reloc %u: bad relocation sym offset\n",
  94                                 module->name, relindex, i);
  95                         return -ENOEXEC;
  96                 }
  97
  98                 sym = ((Elf32_Sym *)symsec->sh_addr) + offset;
  99                 symname = strtab + sym->st_name;
 100
 101                 if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(u32)) {
 102                         pr_err("%s: section %u reloc %u sym '%s': out of bounds relocation, offset %d size %u\n",
 103                                module->name, relindex, i, symname,
 104                                rel->r_offset, dstsec->sh_size);
 105                         return -ENOEXEC;
 106                 }
 107
 108                 loc = dstsec->sh_addr + rel->r_offset;
 109
 110                 switch (ELF32_R_TYPE(rel->r_info)) {
 111                 case R_ARM_NONE:
 112                         /* ignore */
 113                         break;
 114
 115                 case R_ARM_ABS32:
 116                 case R_ARM_TARGET1:
 117                         *(u32 *)loc += sym->st_value;
 118                         break;
 119
 120                 case R_ARM_PC24:
 121                 case R_ARM_CALL:
 122                 case R_ARM_JUMP24:
 123                         if (sym->st_value & 3) {
 124                                 pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (ARM -> Thumb)\n",
 125                                        module->name, relindex, i, symname);
 126                                 return -ENOEXEC;
 127                         }
 128
 129                         offset = __mem_to_opcode_arm(*(u32 *)loc);
 130                         offset = (offset & 0x00ffffff) << 2;
 131                         if (offset & 0x02000000)
 132                                 offset -= 0x04000000;
 133
 134                         offset += sym->st_value - loc;
 135
 136                         /*
 137                          * Route through a PLT entry if 'offset' exceeds the
 138                          * supported range. Note that 'offset + loc + 8'
 139                          * contains the absolute jump target, i.e.,
 140                          * @sym + addend, corrected for the +8 PC bias.
 141                          */
 142                         if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) &&
 143                             (offset <= (s32)0xfe000000 ||
 144                              offset >= (s32)0x02000000))
 145                                 offset = get_module_plt(module, loc,
 146                                                         offset + loc + 8)
 147                                          - loc - 8;
 148
 149                         if (offset <= (s32)0xfe000000 ||
 150                             offset >= (s32)0x02000000) {
 151                                 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
 152                                        module->name, relindex, i, symname,
 153                                        ELF32_R_TYPE(rel->r_info), loc,
 154                                        sym->st_value);
 155                                 return -ENOEXEC;
 156                         }
 157
 158                         offset >>= 2;
 159                         offset &= 0x00ffffff;
 160
 161                         *(u32 *)loc &= __opcode_to_mem_arm(0xff000000);
 162                         *(u32 *)loc |= __opcode_to_mem_arm(offset);
 163                         break;
 164
 165                case R_ARM_V4BX:
 166                        /* Preserve Rm and the condition code. Alter
 167                         * other bits to re-code instruction as
 168                         * MOV PC,Rm.
 169                         */
 170                        *(u32 *)loc &= __opcode_to_mem_arm(0xf000000f);
 171                        *(u32 *)loc |= __opcode_to_mem_arm(0x01a0f000);
 172                        break;
 173
 174                 case R_ARM_PREL31:
 175                         offset = (*(s32 *)loc << 1) >> 1; /* sign extend */
 176                         offset += sym->st_value - loc;
 177                         if (offset >= 0x40000000 || offset < -0x40000000) {
 178                                 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
 179                                        module->name, relindex, i, symname,
 180                                        ELF32_R_TYPE(rel->r_info), loc,
 181                                        sym->st_value);
 182                                 return -ENOEXEC;
 183                         }
 184                         *(u32 *)loc &= 0x80000000;
 185                         *(u32 *)loc |= offset & 0x7fffffff;
 186                         break;
 187
 188                 case R_ARM_REL32:
 189                         *(u32 *)loc += sym->st_value - loc;
 190                         break;
 191
 192                 case R_ARM_MOVW_ABS_NC:
 193                 case R_ARM_MOVT_ABS:
 194                 case R_ARM_MOVW_PREL_NC:
 195                 case R_ARM_MOVT_PREL:
 196                         offset = tmp = __mem_to_opcode_arm(*(u32 *)loc);
 197                         offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
 198                         offset = (offset ^ 0x8000) - 0x8000;
 199
 200                         offset += sym->st_value;
 201                         if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_PREL ||
 202                             ELF32_R_TYPE(rel->r_info) == R_ARM_MOVW_PREL_NC)
 203                                 offset -= loc;
 204                         if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS ||
 205                             ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_PREL)
 206                                 offset >>= 16;
 207
 208                         tmp &= 0xfff0f000;
 209                         tmp |= ((offset & 0xf000) << 4) |
 210                                 (offset & 0x0fff);
 211
 212                         *(u32 *)loc = __opcode_to_mem_arm(tmp);
 213                         break;
 214
 215 #ifdef CONFIG_THUMB2_KERNEL
 216                 case R_ARM_THM_CALL:
 217                 case R_ARM_THM_JUMP24:
 218                         /*
 219                          * For function symbols, only Thumb addresses are
 220                          * allowed (no interworking).
 221                          *
 222                          * For non-function symbols, the destination
 223                          * has no specific ARM/Thumb disposition, so
 224                          * the branch is resolved under the assumption
 225                          * that interworking is not required.
 226                          */
 227                         if (ELF32_ST_TYPE(sym->st_info) == STT_FUNC &&
 228                             !(sym->st_value & 1)) {
 229                                 pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (Thumb -> ARM)\n",
 230                                        module->name, relindex, i, symname);
 231                                 return -ENOEXEC;
 232                         }
 233
 234                         upper = __mem_to_opcode_thumb16(*(u16 *)loc);
 235                         lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));
 236
 237                         /*
 238                          * 25 bit signed address range (Thumb-2 BL and B.W
 239                          * instructions):
 240                          *   S:I1:I2:imm10:imm11:0
 241                          * where:
 242                          *   S     = upper[10]   = offset[24]
 243                          *   I1    = ~(J1 ^ S)   = offset[23]
 244                          *   I2    = ~(J2 ^ S)   = offset[22]
 245                          *   imm10 = upper[9:0]  = offset[21:12]
 246                          *   imm11 = lower[10:0] = offset[11:1]
 247                          *   J1    = lower[13]
 248                          *   J2    = lower[11]
 249                          */
 250                         sign = (upper >> 10) & 1;
 251                         j1 = (lower >> 13) & 1;
 252                         j2 = (lower >> 11) & 1;
 253                         offset = (sign << 24) | ((~(j1 ^ sign) & 1) << 23) |
 254                                 ((~(j2 ^ sign) & 1) << 22) |
 255                                 ((upper & 0x03ff) << 12) |
 256                                 ((lower & 0x07ff) << 1);
 257                         if (offset & 0x01000000)
 258                                 offset -= 0x02000000;
 259                         offset += sym->st_value - loc;
 260
 261                         /*
 262                          * Route through a PLT entry if 'offset' exceeds the
 263                          * supported range.
 264                          */
 265                         if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) &&
 266                             (offset <= (s32)0xff000000 ||
 267                              offset >= (s32)0x01000000))
 268                                 offset = get_module_plt(module, loc,
 269                                                         offset + loc + 4)
 270                                          - loc - 4;
 271
 272                         if (offset <= (s32)0xff000000 ||
 273                             offset >= (s32)0x01000000) {
 274                                 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
 275                                        module->name, relindex, i, symname,
 276                                        ELF32_R_TYPE(rel->r_info), loc,
 277                                        sym->st_value);
 278                                 return -ENOEXEC;
 279                         }
 280
 281                         sign = (offset >> 24) & 1;
 282                         j1 = sign ^ (~(offset >> 23) & 1);
 283                         j2 = sign ^ (~(offset >> 22) & 1);
 284                         upper = (u16)((upper & 0xf800) | (sign << 10) |
 285                                             ((offset >> 12) & 0x03ff));
 286                         lower = (u16)((lower & 0xd000) |
 287                                       (j1 << 13) | (j2 << 11) |
 288                                       ((offset >> 1) & 0x07ff));
 289
 290                         *(u16 *)loc = __opcode_to_mem_thumb16(upper);
 291                         *(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
 292                         break;
 293
 294                 case R_ARM_THM_MOVW_ABS_NC:
 295                 case R_ARM_THM_MOVT_ABS:
 296                 case R_ARM_THM_MOVW_PREL_NC:
 297                 case R_ARM_THM_MOVT_PREL:
 298                         upper = __mem_to_opcode_thumb16(*(u16 *)loc);
 299                         lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));
 300
 301                         /*
 302                          * MOVT/MOVW instructions encoding in Thumb-2:
 303                          *
 304                          * i    = upper[10]
 305                          * imm4 = upper[3:0]
 306                          * imm3 = lower[14:12]
 307                          * imm8 = lower[7:0]
 308                          *
 309                          * imm16 = imm4:i:imm3:imm8
 310                          */
 311                         offset = ((upper & 0x000f) << 12) |
 312                                 ((upper & 0x0400) << 1) |
 313                                 ((lower & 0x7000) >> 4) | (lower & 0x00ff);
 314                         offset = (offset ^ 0x8000) - 0x8000;
 315                         offset += sym->st_value;
 316
 317                         if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_PREL ||
 318                             ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVW_PREL_NC)
 319                                 offset -= loc;
 320                         if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS ||
 321                             ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_PREL)
 322                                 offset >>= 16;
 323
 324                         upper = (u16)((upper & 0xfbf0) |
 325                                       ((offset & 0xf000) >> 12) |
 326                                       ((offset & 0x0800) >> 1));
 327                         lower = (u16)((lower & 0x8f00) |
 328                                       ((offset & 0x0700) << 4) |
 329                                       (offset & 0x00ff));
 330                         *(u16 *)loc = __opcode_to_mem_thumb16(upper);
 331                         *(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
 332                         break;
 333 #endif
 334
 335                 default:
 336                         pr_err("%s: unknown relocation: %u\n",
 337                                module->name, ELF32_R_TYPE(rel->r_info));
 338                         return -ENOEXEC;
 339                 }
 340         }
 341         return 0;
 342 }
 343
 344 struct mod_unwind_map {
 345         const Elf_Shdr *unw_sec;
 346         const Elf_Shdr *txt_sec;
 347 };
 348
 349 static const Elf_Shdr *find_mod_section(const Elf32_Ehdr *hdr,
 350         const Elf_Shdr *sechdrs, const char *name)
 351 {
 352         const Elf_Shdr *s, *se;
 353         const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 354
 355         for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++)
 356                 if (strcmp(name, secstrs + s->sh_name) == 0)
 357                         return s;
 358
 359         return NULL;
 360 }
 361
 362 extern void fixup_pv_table(const void *, unsigned long);
 363 extern void fixup_smp(const void *, unsigned long);
 364
 365 int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
 366                     struct module *mod)
 367 {
 368         const Elf_Shdr *s = NULL;
 369 #ifdef CONFIG_ARM_UNWIND
 370         const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 371         const Elf_Shdr *sechdrs_end = sechdrs + hdr->e_shnum;
 372         struct mod_unwind_map maps[ARM_SEC_MAX];
 373         int i;
 374
 375         memset(maps, 0, sizeof(maps));
 376
 377         for (s = sechdrs; s < sechdrs_end; s++) {
 378                 const char *secname = secstrs + s->sh_name;
 379
 380                 if (!(s->sh_flags & SHF_ALLOC))
 381                         continue;
 382
 383                 if (strcmp(".ARM.exidx.init.text", secname) == 0)
 384                         maps[ARM_SEC_INIT].unw_sec = s;
 385                 else if (strcmp(".ARM.exidx", secname) == 0)
 386                         maps[ARM_SEC_CORE].unw_sec = s;
 387                 else if (strcmp(".ARM.exidx.exit.text", secname) == 0)
 388                         maps[ARM_SEC_EXIT].unw_sec = s;
 389                 else if (strcmp(".ARM.exidx.text.unlikely", secname) == 0)
 390                         maps[ARM_SEC_UNLIKELY].unw_sec = s;
 391                 else if (strcmp(".ARM.exidx.text.hot", secname) == 0)
 392                         maps[ARM_SEC_HOT].unw_sec = s;
 393                 else if (strcmp(".init.text", secname) == 0)
 394                         maps[ARM_SEC_INIT].txt_sec = s;
 395                 else if (strcmp(".text", secname) == 0)
 396                         maps[ARM_SEC_CORE].txt_sec = s;
 397                 else if (strcmp(".exit.text", secname) == 0)
 398                         maps[ARM_SEC_EXIT].txt_sec = s;
 399                 else if (strcmp(".text.unlikely", secname) == 0)
 400                         maps[ARM_SEC_UNLIKELY].txt_sec = s;
 401                 else if (strcmp(".text.hot", secname) == 0)
 402                         maps[ARM_SEC_HOT].txt_sec = s;
 403         }
 404
 405         for (i = 0; i < ARM_SEC_MAX; i++)
 406                 if (maps[i].unw_sec && maps[i].txt_sec)
 407                         mod->arch.unwind[i] =
 408                                 unwind_table_add(maps[i].unw_sec->sh_addr,
 409                                                  maps[i].unw_sec->sh_size,
 410                                                  maps[i].txt_sec->sh_addr,
 411                                                  maps[i].txt_sec->sh_size);
 412 #endif
 413 #ifdef CONFIG_ARM_PATCH_PHYS_VIRT
 414         s = find_mod_section(hdr, sechdrs, ".pv_table");
 415         if (s)
 416                 fixup_pv_table((void *)s->sh_addr, s->sh_size);
 417 #endif
 418         s = find_mod_section(hdr, sechdrs, ".alt.smp.init");
 419         if (s && !is_smp())
 420 #ifdef CONFIG_SMP_ON_UP
 421                 fixup_smp((void *)s->sh_addr, s->sh_size);
 422 #else
 423                 return -EINVAL;
 424 #endif
 425         return 0;
 426 }
 427
 428 void
 429 module_arch_cleanup(struct module *mod)
 430 {
 431 #ifdef CONFIG_ARM_UNWIND
 432         int i;
 433
 434         for (i = 0; i < ARM_SEC_MAX; i++) {
 435                 unwind_table_del(mod->arch.unwind[i]);
 436                 mod->arch.unwind[i] = NULL;
 437         }
 438 #endif
 439 }
 440
 441 void __weak module_arch_freeing_init(struct module *mod)
 442 {
 443 #ifdef CONFIG_ARM_UNWIND
 444         unwind_table_del(mod->arch.unwind[ARM_SEC_INIT]);
 445         mod->arch.unwind[ARM_SEC_INIT] = NULL;
 446 #endif
 447 }