linux/arch/arm/kernel/module.c
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   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
  37void *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
  57bool 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
  64bool 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
  71int
  72apply_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
 344struct mod_unwind_map {
 345        const Elf_Shdr *unw_sec;
 346        const Elf_Shdr *txt_sec;
 347};
 348
 349static 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
 362extern void fixup_pv_table(const void *, unsigned long);
 363extern void fixup_smp(const void *, unsigned long);
 364
 365int 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
 428void
 429module_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
 441void __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}
 448
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