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/pgtable.h>
  21 #include <asm/sections.h>
  22 #include <asm/smp_plat.h>
  23 #include <asm/unwind.h>
  24 #include <asm/opcodes.h>
  25
  26 #ifdef CONFIG_XIP_KERNEL
  27 /*
  28  * The XIP kernel text is mapped in the module area for modules and
  29  * some other stuff to work without any indirect relocations.
  30  * MODULES_VADDR is redefined here and not in asm/memory.h to avoid
  31  * recompiling the whole kernel when CONFIG_XIP_KERNEL is turned on/off.
  32  */
  33 #undef MODULES_VADDR
  34 #define MODULES_VADDR   (((unsigned long)_exiprom + ~PMD_MASK) & PMD_MASK)
  35 #endif
  36
  37 #ifdef CONFIG_MMU
  38 void *module_alloc(unsigned long size)
  39 {
  40         gfp_t gfp_mask = GFP_KERNEL;
  41         void *p;
  42
  43         /* Silence the initial allocation */
  44         if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS))
  45                 gfp_mask |= __GFP_NOWARN;
  46
  47         p = __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
  48                                 gfp_mask, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
  49                                 __builtin_return_address(0));
  50         if (!IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || p)
  51                 return p;
  52         return __vmalloc_node_range(size, 1,  VMALLOC_START, VMALLOC_END,
  53                                 GFP_KERNEL, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
  54                                 __builtin_return_address(0));
  55 }
  56 #endif
  57
  58 bool module_exit_section(const char *name)
  59 {
  60         return strstarts(name, ".exit") ||
  61                 strstarts(name, ".ARM.extab.exit") ||
  62                 strstarts(name, ".ARM.exidx.exit");
  63 }
  64
  65 int
  66 apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
  67                unsigned int relindex, struct module *module)
  68 {
  69         Elf32_Shdr *symsec = sechdrs + symindex;
  70         Elf32_Shdr *relsec = sechdrs + relindex;
  71         Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
  72         Elf32_Rel *rel = (void *)relsec->sh_addr;
  73         unsigned int i;
  74
  75         for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++, rel++) {
  76                 unsigned long loc;
  77                 Elf32_Sym *sym;
  78                 const char *symname;
  79                 s32 offset;
  80                 u32 tmp;
  81 #ifdef CONFIG_THUMB2_KERNEL
  82                 u32 upper, lower, sign, j1, j2;
  83 #endif
  84
  85                 offset = ELF32_R_SYM(rel->r_info);
  86                 if (offset < 0 || offset > (symsec->sh_size / sizeof(Elf32_Sym))) {
  87                         pr_err("%s: section %u reloc %u: bad relocation sym offset\n",
  88                                 module->name, relindex, i);
  89                         return -ENOEXEC;
  90                 }
  91
  92                 sym = ((Elf32_Sym *)symsec->sh_addr) + offset;
  93                 symname = strtab + sym->st_name;
  94
  95                 if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(u32)) {
  96                         pr_err("%s: section %u reloc %u sym '%s': out of bounds relocation, offset %d size %u\n",
  97                                module->name, relindex, i, symname,
  98                                rel->r_offset, dstsec->sh_size);
  99                         return -ENOEXEC;
 100                 }
 101
 102                 loc = dstsec->sh_addr + rel->r_offset;
 103
 104                 switch (ELF32_R_TYPE(rel->r_info)) {
 105                 case R_ARM_NONE:
 106                         /* ignore */
 107                         break;
 108
 109                 case R_ARM_ABS32:
 110                 case R_ARM_TARGET1:
 111                         *(u32 *)loc += sym->st_value;
 112                         break;
 113
 114                 case R_ARM_PC24:
 115                 case R_ARM_CALL:
 116                 case R_ARM_JUMP24:
 117                         if (sym->st_value & 3) {
 118                                 pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (ARM -> Thumb)\n",
 119                                        module->name, relindex, i, symname);
 120                                 return -ENOEXEC;
 121                         }
 122
 123                         offset = __mem_to_opcode_arm(*(u32 *)loc);
 124                         offset = (offset & 0x00ffffff) << 2;
 125                         if (offset & 0x02000000)
 126                                 offset -= 0x04000000;
 127
 128                         offset += sym->st_value - loc;
 129
 130                         /*
 131                          * Route through a PLT entry if 'offset' exceeds the
 132                          * supported range. Note that 'offset + loc + 8'
 133                          * contains the absolute jump target, i.e.,
 134                          * @sym + addend, corrected for the +8 PC bias.
 135                          */
 136                         if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) &&
 137                             (offset <= (s32)0xfe000000 ||
 138                              offset >= (s32)0x02000000))
 139                                 offset = get_module_plt(module, loc,
 140                                                         offset + loc + 8)
 141                                          - loc - 8;
 142
 143                         if (offset <= (s32)0xfe000000 ||
 144                             offset >= (s32)0x02000000) {
 145                                 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
 146                                        module->name, relindex, i, symname,
 147                                        ELF32_R_TYPE(rel->r_info), loc,
 148                                        sym->st_value);
 149                                 return -ENOEXEC;
 150                         }
 151
 152                         offset >>= 2;
 153                         offset &= 0x00ffffff;
 154
 155                         *(u32 *)loc &= __opcode_to_mem_arm(0xff000000);
 156                         *(u32 *)loc |= __opcode_to_mem_arm(offset);
 157                         break;
 158
 159                case R_ARM_V4BX:
 160                        /* Preserve Rm and the condition code. Alter
 161                         * other bits to re-code instruction as
 162                         * MOV PC,Rm.
 163                         */
 164                        *(u32 *)loc &= __opcode_to_mem_arm(0xf000000f);
 165                        *(u32 *)loc |= __opcode_to_mem_arm(0x01a0f000);
 166                        break;
 167
 168                 case R_ARM_PREL31:
 169                         offset = (*(s32 *)loc << 1) >> 1; /* sign extend */
 170                         offset += sym->st_value - loc;
 171                         if (offset >= 0x40000000 || offset < -0x40000000) {
 172                                 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
 173                                        module->name, relindex, i, symname,
 174                                        ELF32_R_TYPE(rel->r_info), loc,
 175                                        sym->st_value);
 176                                 return -ENOEXEC;
 177                         }
 178                         *(u32 *)loc &= 0x80000000;
 179                         *(u32 *)loc |= offset & 0x7fffffff;
 180                         break;
 181
 182                 case R_ARM_MOVW_ABS_NC:
 183                 case R_ARM_MOVT_ABS:
 184                         offset = tmp = __mem_to_opcode_arm(*(u32 *)loc);
 185                         offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
 186                         offset = (offset ^ 0x8000) - 0x8000;
 187
 188                         offset += sym->st_value;
 189                         if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS)
 190                                 offset >>= 16;
 191
 192                         tmp &= 0xfff0f000;
 193                         tmp |= ((offset & 0xf000) << 4) |
 194                                 (offset & 0x0fff);
 195
 196                         *(u32 *)loc = __opcode_to_mem_arm(tmp);
 197                         break;
 198
 199 #ifdef CONFIG_THUMB2_KERNEL
 200                 case R_ARM_THM_CALL:
 201                 case R_ARM_THM_JUMP24:
 202                         /*
 203                          * For function symbols, only Thumb addresses are
 204                          * allowed (no interworking).
 205                          *
 206                          * For non-function symbols, the destination
 207                          * has no specific ARM/Thumb disposition, so
 208                          * the branch is resolved under the assumption
 209                          * that interworking is not required.
 210                          */
 211                         if (ELF32_ST_TYPE(sym->st_info) == STT_FUNC &&
 212                             !(sym->st_value & 1)) {
 213                                 pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (Thumb -> ARM)\n",
 214                                        module->name, relindex, i, symname);
 215                                 return -ENOEXEC;
 216                         }
 217
 218                         upper = __mem_to_opcode_thumb16(*(u16 *)loc);
 219                         lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));
 220
 221                         /*
 222                          * 25 bit signed address range (Thumb-2 BL and B.W
 223                          * instructions):
 224                          *   S:I1:I2:imm10:imm11:0
 225                          * where:
 226                          *   S     = upper[10]   = offset[24]
 227                          *   I1    = ~(J1 ^ S)   = offset[23]
 228                          *   I2    = ~(J2 ^ S)   = offset[22]
 229                          *   imm10 = upper[9:0]  = offset[21:12]
 230                          *   imm11 = lower[10:0] = offset[11:1]
 231                          *   J1    = lower[13]
 232                          *   J2    = lower[11]
 233                          */
 234                         sign = (upper >> 10) & 1;
 235                         j1 = (lower >> 13) & 1;
 236                         j2 = (lower >> 11) & 1;
 237                         offset = (sign << 24) | ((~(j1 ^ sign) & 1) << 23) |
 238                                 ((~(j2 ^ sign) & 1) << 22) |
 239                                 ((upper & 0x03ff) << 12) |
 240                                 ((lower & 0x07ff) << 1);
 241                         if (offset & 0x01000000)
 242                                 offset -= 0x02000000;
 243                         offset += sym->st_value - loc;
 244
 245                         /*
 246                          * Route through a PLT entry if 'offset' exceeds the
 247                          * supported range.
 248                          */
 249                         if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) &&
 250                             (offset <= (s32)0xff000000 ||
 251                              offset >= (s32)0x01000000))
 252                                 offset = get_module_plt(module, loc,
 253                                                         offset + loc + 4)
 254                                          - loc - 4;
 255
 256                         if (offset <= (s32)0xff000000 ||
 257                             offset >= (s32)0x01000000) {
 258                                 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
 259                                        module->name, relindex, i, symname,
 260                                        ELF32_R_TYPE(rel->r_info), loc,
 261                                        sym->st_value);
 262                                 return -ENOEXEC;
 263                         }
 264
 265                         sign = (offset >> 24) & 1;
 266                         j1 = sign ^ (~(offset >> 23) & 1);
 267                         j2 = sign ^ (~(offset >> 22) & 1);
 268                         upper = (u16)((upper & 0xf800) | (sign << 10) |
 269                                             ((offset >> 12) & 0x03ff));
 270                         lower = (u16)((lower & 0xd000) |
 271                                       (j1 << 13) | (j2 << 11) |
 272                                       ((offset >> 1) & 0x07ff));
 273
 274                         *(u16 *)loc = __opcode_to_mem_thumb16(upper);
 275                         *(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
 276                         break;
 277
 278                 case R_ARM_THM_MOVW_ABS_NC:
 279                 case R_ARM_THM_MOVT_ABS:
 280                         upper = __mem_to_opcode_thumb16(*(u16 *)loc);
 281                         lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));
 282
 283                         /*
 284                          * MOVT/MOVW instructions encoding in Thumb-2:
 285                          *
 286                          * i    = upper[10]
 287                          * imm4 = upper[3:0]
 288                          * imm3 = lower[14:12]
 289                          * imm8 = lower[7:0]
 290                          *
 291                          * imm16 = imm4:i:imm3:imm8
 292                          */
 293                         offset = ((upper & 0x000f) << 12) |
 294                                 ((upper & 0x0400) << 1) |
 295                                 ((lower & 0x7000) >> 4) | (lower & 0x00ff);
 296                         offset = (offset ^ 0x8000) - 0x8000;
 297                         offset += sym->st_value;
 298
 299                         if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS)
 300                                 offset >>= 16;
 301
 302                         upper = (u16)((upper & 0xfbf0) |
 303                                       ((offset & 0xf000) >> 12) |
 304                                       ((offset & 0x0800) >> 1));
 305                         lower = (u16)((lower & 0x8f00) |
 306                                       ((offset & 0x0700) << 4) |
 307                                       (offset & 0x00ff));
 308                         *(u16 *)loc = __opcode_to_mem_thumb16(upper);
 309                         *(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
 310                         break;
 311 #endif
 312
 313                 default:
 314                         pr_err("%s: unknown relocation: %u\n",
 315                                module->name, ELF32_R_TYPE(rel->r_info));
 316                         return -ENOEXEC;
 317                 }
 318         }
 319         return 0;
 320 }
 321
 322 struct mod_unwind_map {
 323         const Elf_Shdr *unw_sec;
 324         const Elf_Shdr *txt_sec;
 325 };
 326
 327 static const Elf_Shdr *find_mod_section(const Elf32_Ehdr *hdr,
 328         const Elf_Shdr *sechdrs, const char *name)
 329 {
 330         const Elf_Shdr *s, *se;
 331         const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 332
 333         for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++)
 334                 if (strcmp(name, secstrs + s->sh_name) == 0)
 335                         return s;
 336
 337         return NULL;
 338 }
 339
 340 extern void fixup_pv_table(const void *, unsigned long);
 341 extern void fixup_smp(const void *, unsigned long);
 342
 343 int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
 344                     struct module *mod)
 345 {
 346         const Elf_Shdr *s = NULL;
 347 #ifdef CONFIG_ARM_UNWIND
 348         const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 349         const Elf_Shdr *sechdrs_end = sechdrs + hdr->e_shnum;
 350         struct mod_unwind_map maps[ARM_SEC_MAX];
 351         int i;
 352
 353         memset(maps, 0, sizeof(maps));
 354
 355         for (s = sechdrs; s < sechdrs_end; s++) {
 356                 const char *secname = secstrs + s->sh_name;
 357
 358                 if (!(s->sh_flags & SHF_ALLOC))
 359                         continue;
 360
 361                 if (strcmp(".ARM.exidx.init.text", secname) == 0)
 362                         maps[ARM_SEC_INIT].unw_sec = s;
 363                 else if (strcmp(".ARM.exidx", secname) == 0)
 364                         maps[ARM_SEC_CORE].unw_sec = s;
 365                 else if (strcmp(".ARM.exidx.exit.text", secname) == 0)
 366                         maps[ARM_SEC_EXIT].unw_sec = s;
 367                 else if (strcmp(".ARM.exidx.text.unlikely", secname) == 0)
 368                         maps[ARM_SEC_UNLIKELY].unw_sec = s;
 369                 else if (strcmp(".ARM.exidx.text.hot", secname) == 0)
 370                         maps[ARM_SEC_HOT].unw_sec = s;
 371                 else if (strcmp(".init.text", secname) == 0)
 372                         maps[ARM_SEC_INIT].txt_sec = s;
 373                 else if (strcmp(".text", secname) == 0)
 374                         maps[ARM_SEC_CORE].txt_sec = s;
 375                 else if (strcmp(".exit.text", secname) == 0)
 376                         maps[ARM_SEC_EXIT].txt_sec = s;
 377                 else if (strcmp(".text.unlikely", secname) == 0)
 378                         maps[ARM_SEC_UNLIKELY].txt_sec = s;
 379                 else if (strcmp(".text.hot", secname) == 0)
 380                         maps[ARM_SEC_HOT].txt_sec = s;
 381         }
 382
 383         for (i = 0; i < ARM_SEC_MAX; i++)
 384                 if (maps[i].unw_sec && maps[i].txt_sec)
 385                         mod->arch.unwind[i] =
 386                                 unwind_table_add(maps[i].unw_sec->sh_addr,
 387                                                  maps[i].unw_sec->sh_size,
 388                                                  maps[i].txt_sec->sh_addr,
 389                                                  maps[i].txt_sec->sh_size);
 390 #endif
 391 #ifdef CONFIG_ARM_PATCH_PHYS_VIRT
 392         s = find_mod_section(hdr, sechdrs, ".pv_table");
 393         if (s)
 394                 fixup_pv_table((void *)s->sh_addr, s->sh_size);
 395 #endif
 396         s = find_mod_section(hdr, sechdrs, ".alt.smp.init");
 397         if (s && !is_smp())
 398 #ifdef CONFIG_SMP_ON_UP
 399                 fixup_smp((void *)s->sh_addr, s->sh_size);
 400 #else
 401                 return -EINVAL;
 402 #endif
 403         return 0;
 404 }
 405
 406 void
 407 module_arch_cleanup(struct module *mod)
 408 {
 409 #ifdef CONFIG_ARM_UNWIND
 410         int i;
 411
 412         for (i = 0; i < ARM_SEC_MAX; i++)
 413                 if (mod->arch.unwind[i])
 414                         unwind_table_del(mod->arch.unwind[i]);
 415 #endif
 416 }