arch/arm/kernel/module.c

   1 /*
   2  *  linux/arch/arm/kernel/module.c
   3  *
   4  *  Copyright (C) 2002 Russell King.
   5  *  Modified for nommu by Hyok S. Choi
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * Module allocation method suggested by Andi Kleen.
  12  */
  13 #include <linux/module.h>
  14 #include <linux/moduleloader.h>
  15 #include <linux/kernel.h>
  16 #include <linux/mm.h>
  17 #include <linux/elf.h>
  18 #include <linux/vmalloc.h>
  19 #include <linux/fs.h>
  20 #include <linux/string.h>
  21 #include <linux/gfp.h>
  22
  23 #include <asm/pgtable.h>
  24 #include <asm/sections.h>
  25 #include <asm/smp_plat.h>
  26 #include <asm/unwind.h>
  27 #include <asm/opcodes.h>
  28
  29 #ifdef CONFIG_XIP_KERNEL
  30 /*
  31  * The XIP kernel text is mapped in the module area for modules and
  32  * some other stuff to work without any indirect relocations.
  33  * MODULES_VADDR is redefined here and not in asm/memory.h to avoid
  34  * recompiling the whole kernel when CONFIG_XIP_KERNEL is turned on/off.
  35  */
  36 #undef MODULES_VADDR
  37 #define MODULES_VADDR   (((unsigned long)_exiprom + ~PMD_MASK) & PMD_MASK)
  38 #endif
  39
  40 #ifdef CONFIG_MMU
  41 void *module_alloc(unsigned long size)
  42 {
  43         void *p = __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
  44                                 GFP_KERNEL, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
  45                                 __builtin_return_address(0));
  46         if (!IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || p)
  47                 return p;
  48         return __vmalloc_node_range(size, 1,  VMALLOC_START, VMALLOC_END,
  49                                 GFP_KERNEL, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
  50                                 __builtin_return_address(0));
  51 }
  52 #endif
  53
  54 int
  55 apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
  56                unsigned int relindex, struct module *module)
  57 {
  58         Elf32_Shdr *symsec = sechdrs + symindex;
  59         Elf32_Shdr *relsec = sechdrs + relindex;
  60         Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
  61         Elf32_Rel *rel = (void *)relsec->sh_addr;
  62         unsigned int i;
  63
  64         for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++, rel++) {
  65                 unsigned long loc;
  66                 Elf32_Sym *sym;
  67                 const char *symname;
  68                 s32 offset;
  69                 u32 tmp;
  70 #ifdef CONFIG_THUMB2_KERNEL
  71                 u32 upper, lower, sign, j1, j2;
  72 #endif
  73
  74                 offset = ELF32_R_SYM(rel->r_info);
  75                 if (offset < 0 || offset > (symsec->sh_size / sizeof(Elf32_Sym))) {
  76                         pr_err("%s: section %u reloc %u: bad relocation sym offset\n",
  77                                 module->name, relindex, i);
  78                         return -ENOEXEC;
  79                 }
  80
  81                 sym = ((Elf32_Sym *)symsec->sh_addr) + offset;
  82                 symname = strtab + sym->st_name;
  83
  84                 if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(u32)) {
  85                         pr_err("%s: section %u reloc %u sym '%s': out of bounds relocation, offset %d size %u\n",
  86                                module->name, relindex, i, symname,
  87                                rel->r_offset, dstsec->sh_size);
  88                         return -ENOEXEC;
  89                 }
  90
  91                 loc = dstsec->sh_addr + rel->r_offset;
  92
  93                 switch (ELF32_R_TYPE(rel->r_info)) {
  94                 case R_ARM_NONE:
  95                         /* ignore */
  96                         break;
  97
  98                 case R_ARM_ABS32:
  99                 case R_ARM_TARGET1:
 100                         *(u32 *)loc += sym->st_value;
 101                         break;
 102
 103                 case R_ARM_PC24:
 104                 case R_ARM_CALL:
 105                 case R_ARM_JUMP24:
 106                         if (sym->st_value & 3) {
 107                                 pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (ARM -> Thumb)\n",
 108                                        module->name, relindex, i, symname);
 109                                 return -ENOEXEC;
 110                         }
 111
 112                         offset = __mem_to_opcode_arm(*(u32 *)loc);
 113                         offset = (offset & 0x00ffffff) << 2;
 114                         if (offset & 0x02000000)
 115                                 offset -= 0x04000000;
 116
 117                         offset += sym->st_value - loc;
 118
 119                         /*
 120                          * Route through a PLT entry if 'offset' exceeds the
 121                          * supported range. Note that 'offset + loc + 8'
 122                          * contains the absolute jump target, i.e.,
 123                          * @sym + addend, corrected for the +8 PC bias.
 124                          */
 125                         if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) &&
 126                             (offset <= (s32)0xfe000000 ||
 127                              offset >= (s32)0x02000000))
 128                                 offset = get_module_plt(module, loc,
 129                                                         offset + loc + 8)
 130                                          - loc - 8;
 131
 132                         if (offset <= (s32)0xfe000000 ||
 133                             offset >= (s32)0x02000000) {
 134                                 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
 135                                        module->name, relindex, i, symname,
 136                                        ELF32_R_TYPE(rel->r_info), loc,
 137                                        sym->st_value);
 138                                 return -ENOEXEC;
 139                         }
 140
 141                         offset >>= 2;
 142                         offset &= 0x00ffffff;
 143
 144                         *(u32 *)loc &= __opcode_to_mem_arm(0xff000000);
 145                         *(u32 *)loc |= __opcode_to_mem_arm(offset);
 146                         break;
 147
 148                case R_ARM_V4BX:
 149                        /* Preserve Rm and the condition code. Alter
 150                         * other bits to re-code instruction as
 151                         * MOV PC,Rm.
 152                         */
 153                        *(u32 *)loc &= __opcode_to_mem_arm(0xf000000f);
 154                        *(u32 *)loc |= __opcode_to_mem_arm(0x01a0f000);
 155                        break;
 156
 157                 case R_ARM_PREL31:
 158                         offset = (*(s32 *)loc << 1) >> 1; /* sign extend */
 159                         offset += sym->st_value - loc;
 160                         if (offset >= 0x40000000 || offset < -0x40000000) {
 161                                 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
 162                                        module->name, relindex, i, symname,
 163                                        ELF32_R_TYPE(rel->r_info), loc,
 164                                        sym->st_value);
 165                                 return -ENOEXEC;
 166                         }
 167                         *(u32 *)loc &= 0x80000000;
 168                         *(u32 *)loc |= offset & 0x7fffffff;
 169                         break;
 170
 171                 case R_ARM_MOVW_ABS_NC:
 172                 case R_ARM_MOVT_ABS:
 173                         offset = tmp = __mem_to_opcode_arm(*(u32 *)loc);
 174                         offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
 175                         offset = (offset ^ 0x8000) - 0x8000;
 176
 177                         offset += sym->st_value;
 178                         if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS)
 179                                 offset >>= 16;
 180
 181                         tmp &= 0xfff0f000;
 182                         tmp |= ((offset & 0xf000) << 4) |
 183                                 (offset & 0x0fff);
 184
 185                         *(u32 *)loc = __opcode_to_mem_arm(tmp);
 186                         break;
 187
 188 #ifdef CONFIG_THUMB2_KERNEL
 189                 case R_ARM_THM_CALL:
 190                 case R_ARM_THM_JUMP24:
 191                         /*
 192                          * For function symbols, only Thumb addresses are
 193                          * allowed (no interworking).
 194                          *
 195                          * For non-function symbols, the destination
 196                          * has no specific ARM/Thumb disposition, so
 197                          * the branch is resolved under the assumption
 198                          * that interworking is not required.
 199                          */
 200                         if (ELF32_ST_TYPE(sym->st_info) == STT_FUNC &&
 201                             !(sym->st_value & 1)) {
 202                                 pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (Thumb -> ARM)\n",
 203                                        module->name, relindex, i, symname);
 204                                 return -ENOEXEC;
 205                         }
 206
 207                         upper = __mem_to_opcode_thumb16(*(u16 *)loc);
 208                         lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));
 209
 210                         /*
 211                          * 25 bit signed address range (Thumb-2 BL and B.W
 212                          * instructions):
 213                          *   S:I1:I2:imm10:imm11:0
 214                          * where:
 215                          *   S     = upper[10]   = offset[24]
 216                          *   I1    = ~(J1 ^ S)   = offset[23]
 217                          *   I2    = ~(J2 ^ S)   = offset[22]
 218                          *   imm10 = upper[9:0]  = offset[21:12]
 219                          *   imm11 = lower[10:0] = offset[11:1]
 220                          *   J1    = lower[13]
 221                          *   J2    = lower[11]
 222                          */
 223                         sign = (upper >> 10) & 1;
 224                         j1 = (lower >> 13) & 1;
 225                         j2 = (lower >> 11) & 1;
 226                         offset = (sign << 24) | ((~(j1 ^ sign) & 1) << 23) |
 227                                 ((~(j2 ^ sign) & 1) << 22) |
 228                                 ((upper & 0x03ff) << 12) |
 229                                 ((lower & 0x07ff) << 1);
 230                         if (offset & 0x01000000)
 231                                 offset -= 0x02000000;
 232                         offset += sym->st_value - loc;
 233
 234                         /*
 235                          * Route through a PLT entry if 'offset' exceeds the
 236                          * supported range.
 237                          */
 238                         if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) &&
 239                             (offset <= (s32)0xff000000 ||
 240                              offset >= (s32)0x01000000))
 241                                 offset = get_module_plt(module, loc,
 242                                                         offset + loc + 4)
 243                                          - loc - 4;
 244
 245                         if (offset <= (s32)0xff000000 ||
 246                             offset >= (s32)0x01000000) {
 247                                 pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
 248                                        module->name, relindex, i, symname,
 249                                        ELF32_R_TYPE(rel->r_info), loc,
 250                                        sym->st_value);
 251                                 return -ENOEXEC;
 252                         }
 253
 254                         sign = (offset >> 24) & 1;
 255                         j1 = sign ^ (~(offset >> 23) & 1);
 256                         j2 = sign ^ (~(offset >> 22) & 1);
 257                         upper = (u16)((upper & 0xf800) | (sign << 10) |
 258                                             ((offset >> 12) & 0x03ff));
 259                         lower = (u16)((lower & 0xd000) |
 260                                       (j1 << 13) | (j2 << 11) |
 261                                       ((offset >> 1) & 0x07ff));
 262
 263                         *(u16 *)loc = __opcode_to_mem_thumb16(upper);
 264                         *(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
 265                         break;
 266
 267                 case R_ARM_THM_MOVW_ABS_NC:
 268                 case R_ARM_THM_MOVT_ABS:
 269                         upper = __mem_to_opcode_thumb16(*(u16 *)loc);
 270                         lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));
 271
 272                         /*
 273                          * MOVT/MOVW instructions encoding in Thumb-2:
 274                          *
 275                          * i    = upper[10]
 276                          * imm4 = upper[3:0]
 277                          * imm3 = lower[14:12]
 278                          * imm8 = lower[7:0]
 279                          *
 280                          * imm16 = imm4:i:imm3:imm8
 281                          */
 282                         offset = ((upper & 0x000f) << 12) |
 283                                 ((upper & 0x0400) << 1) |
 284                                 ((lower & 0x7000) >> 4) | (lower & 0x00ff);
 285                         offset = (offset ^ 0x8000) - 0x8000;
 286                         offset += sym->st_value;
 287
 288                         if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS)
 289                                 offset >>= 16;
 290
 291                         upper = (u16)((upper & 0xfbf0) |
 292                                       ((offset & 0xf000) >> 12) |
 293                                       ((offset & 0x0800) >> 1));
 294                         lower = (u16)((lower & 0x8f00) |
 295                                       ((offset & 0x0700) << 4) |
 296                                       (offset & 0x00ff));
 297                         *(u16 *)loc = __opcode_to_mem_thumb16(upper);
 298                         *(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
 299                         break;
 300 #endif
 301
 302                 default:
 303                         pr_err("%s: unknown relocation: %u\n",
 304                                module->name, ELF32_R_TYPE(rel->r_info));
 305                         return -ENOEXEC;
 306                 }
 307         }
 308         return 0;
 309 }
 310
 311 struct mod_unwind_map {
 312         const Elf_Shdr *unw_sec;
 313         const Elf_Shdr *txt_sec;
 314 };
 315
 316 static const Elf_Shdr *find_mod_section(const Elf32_Ehdr *hdr,
 317         const Elf_Shdr *sechdrs, const char *name)
 318 {
 319         const Elf_Shdr *s, *se;
 320         const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 321
 322         for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++)
 323                 if (strcmp(name, secstrs + s->sh_name) == 0)
 324                         return s;
 325
 326         return NULL;
 327 }
 328
 329 extern void fixup_pv_table(const void *, unsigned long);
 330 extern void fixup_smp(const void *, unsigned long);
 331
 332 int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
 333                     struct module *mod)
 334 {
 335         const Elf_Shdr *s = NULL;
 336 #ifdef CONFIG_ARM_UNWIND
 337         const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 338         const Elf_Shdr *sechdrs_end = sechdrs + hdr->e_shnum;
 339         struct mod_unwind_map maps[ARM_SEC_MAX];
 340         int i;
 341
 342         memset(maps, 0, sizeof(maps));
 343
 344         for (s = sechdrs; s < sechdrs_end; s++) {
 345                 const char *secname = secstrs + s->sh_name;
 346
 347                 if (!(s->sh_flags & SHF_ALLOC))
 348                         continue;
 349
 350                 if (strcmp(".ARM.exidx.init.text", secname) == 0)
 351                         maps[ARM_SEC_INIT].unw_sec = s;
 352                 else if (strcmp(".ARM.exidx", secname) == 0)
 353                         maps[ARM_SEC_CORE].unw_sec = s;
 354                 else if (strcmp(".ARM.exidx.exit.text", secname) == 0)
 355                         maps[ARM_SEC_EXIT].unw_sec = s;
 356                 else if (strcmp(".ARM.exidx.text.unlikely", secname) == 0)
 357                         maps[ARM_SEC_UNLIKELY].unw_sec = s;
 358                 else if (strcmp(".ARM.exidx.text.hot", secname) == 0)
 359                         maps[ARM_SEC_HOT].unw_sec = s;
 360                 else if (strcmp(".init.text", secname) == 0)
 361                         maps[ARM_SEC_INIT].txt_sec = s;
 362                 else if (strcmp(".text", secname) == 0)
 363                         maps[ARM_SEC_CORE].txt_sec = s;
 364                 else if (strcmp(".exit.text", secname) == 0)
 365                         maps[ARM_SEC_EXIT].txt_sec = s;
 366                 else if (strcmp(".text.unlikely", secname) == 0)
 367                         maps[ARM_SEC_UNLIKELY].txt_sec = s;
 368                 else if (strcmp(".text.hot", secname) == 0)
 369                         maps[ARM_SEC_HOT].txt_sec = s;
 370         }
 371
 372         for (i = 0; i < ARM_SEC_MAX; i++)
 373                 if (maps[i].unw_sec && maps[i].txt_sec)
 374                         mod->arch.unwind[i] =
 375                                 unwind_table_add(maps[i].unw_sec->sh_addr,
 376                                                  maps[i].unw_sec->sh_size,
 377                                                  maps[i].txt_sec->sh_addr,
 378                                                  maps[i].txt_sec->sh_size);
 379 #endif
 380 #ifdef CONFIG_ARM_PATCH_PHYS_VIRT
 381         s = find_mod_section(hdr, sechdrs, ".pv_table");
 382         if (s)
 383                 fixup_pv_table((void *)s->sh_addr, s->sh_size);
 384 #endif
 385         s = find_mod_section(hdr, sechdrs, ".alt.smp.init");
 386         if (s && !is_smp())
 387 #ifdef CONFIG_SMP_ON_UP
 388                 fixup_smp((void *)s->sh_addr, s->sh_size);
 389 #else
 390                 return -EINVAL;
 391 #endif
 392         return 0;
 393 }
 394
 395 void
 396 module_arch_cleanup(struct module *mod)
 397 {
 398 #ifdef CONFIG_ARM_UNWIND
 399         int i;
 400
 401         for (i = 0; i < ARM_SEC_MAX; i++)
 402                 if (mod->arch.unwind[i])
 403                         unwind_table_del(mod->arch.unwind[i]);
 404 #endif
 405 }