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