arch/riscv/kernel/module.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *
   4  *  Copyright (C) 2017 Zihao Yu
   5  */
   6
   7 #include <linux/elf.h>
   8 #include <linux/err.h>
   9 #include <linux/errno.h>
  10 #include <linux/moduleloader.h>
  11 #include <linux/vmalloc.h>
  12 #include <linux/sizes.h>
  13 #include <asm/pgtable.h>
  14 #include <asm/sections.h>
  15
  16 /*
  17  * The auipc+jalr instruction pair can reach any PC-relative offset
  18  * in the range [-2^31 - 2^11, 2^31 - 2^11)
  19  */
  20 static bool riscv_insn_valid_32bit_offset(ptrdiff_t val)
  21 {
  22 #ifdef CONFIG_32BIT
  23         return true;
  24 #else
  25         return (-(1L << 31) - (1L << 11)) <= val && val < ((1L << 31) - (1L << 11));
  26 #endif
  27 }
  28
  29 static int apply_r_riscv_32_rela(struct module *me, u32 *location, Elf_Addr v)
  30 {
  31         if (v != (u32)v) {
  32                 pr_err("%s: value %016llx out of range for 32-bit field\n",
  33                        me->name, (long long)v);
  34                 return -EINVAL;
  35         }
  36         *location = v;
  37         return 0;
  38 }
  39
  40 static int apply_r_riscv_64_rela(struct module *me, u32 *location, Elf_Addr v)
  41 {
  42         *(u64 *)location = v;
  43         return 0;
  44 }
  45
  46 static int apply_r_riscv_branch_rela(struct module *me, u32 *location,
  47                                      Elf_Addr v)
  48 {
  49         ptrdiff_t offset = (void *)v - (void *)location;
  50         u32 imm12 = (offset & 0x1000) << (31 - 12);
  51         u32 imm11 = (offset & 0x800) >> (11 - 7);
  52         u32 imm10_5 = (offset & 0x7e0) << (30 - 10);
  53         u32 imm4_1 = (offset & 0x1e) << (11 - 4);
  54
  55         *location = (*location & 0x1fff07f) | imm12 | imm11 | imm10_5 | imm4_1;
  56         return 0;
  57 }
  58
  59 static int apply_r_riscv_jal_rela(struct module *me, u32 *location,
  60                                   Elf_Addr v)
  61 {
  62         ptrdiff_t offset = (void *)v - (void *)location;
  63         u32 imm20 = (offset & 0x100000) << (31 - 20);
  64         u32 imm19_12 = (offset & 0xff000);
  65         u32 imm11 = (offset & 0x800) << (20 - 11);
  66         u32 imm10_1 = (offset & 0x7fe) << (30 - 10);
  67
  68         *location = (*location & 0xfff) | imm20 | imm19_12 | imm11 | imm10_1;
  69         return 0;
  70 }
  71
  72 static int apply_r_riscv_rcv_branch_rela(struct module *me, u32 *location,
  73                                          Elf_Addr v)
  74 {
  75         ptrdiff_t offset = (void *)v - (void *)location;
  76         u16 imm8 = (offset & 0x100) << (12 - 8);
  77         u16 imm7_6 = (offset & 0xc0) >> (6 - 5);
  78         u16 imm5 = (offset & 0x20) >> (5 - 2);
  79         u16 imm4_3 = (offset & 0x18) << (12 - 5);
  80         u16 imm2_1 = (offset & 0x6) << (12 - 10);
  81
  82         *(u16 *)location = (*(u16 *)location & 0xe383) |
  83                     imm8 | imm7_6 | imm5 | imm4_3 | imm2_1;
  84         return 0;
  85 }
  86
  87 static int apply_r_riscv_rvc_jump_rela(struct module *me, u32 *location,
  88                                        Elf_Addr v)
  89 {
  90         ptrdiff_t offset = (void *)v - (void *)location;
  91         u16 imm11 = (offset & 0x800) << (12 - 11);
  92         u16 imm10 = (offset & 0x400) >> (10 - 8);
  93         u16 imm9_8 = (offset & 0x300) << (12 - 11);
  94         u16 imm7 = (offset & 0x80) >> (7 - 6);
  95         u16 imm6 = (offset & 0x40) << (12 - 11);
  96         u16 imm5 = (offset & 0x20) >> (5 - 2);
  97         u16 imm4 = (offset & 0x10) << (12 - 5);
  98         u16 imm3_1 = (offset & 0xe) << (12 - 10);
  99
 100         *(u16 *)location = (*(u16 *)location & 0xe003) |
 101                     imm11 | imm10 | imm9_8 | imm7 | imm6 | imm5 | imm4 | imm3_1;
 102         return 0;
 103 }
 104
 105 static int apply_r_riscv_pcrel_hi20_rela(struct module *me, u32 *location,
 106                                          Elf_Addr v)
 107 {
 108         ptrdiff_t offset = (void *)v - (void *)location;
 109         s32 hi20;
 110
 111         if (!riscv_insn_valid_32bit_offset(offset)) {
 112                 pr_err(
 113                   "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
 114                   me->name, (long long)v, location);
 115                 return -EINVAL;
 116         }
 117
 118         hi20 = (offset + 0x800) & 0xfffff000;
 119         *location = (*location & 0xfff) | hi20;
 120         return 0;
 121 }
 122
 123 static int apply_r_riscv_pcrel_lo12_i_rela(struct module *me, u32 *location,
 124                                            Elf_Addr v)
 125 {
 126         /*
 127          * v is the lo12 value to fill. It is calculated before calling this
 128          * handler.
 129          */
 130         *location = (*location & 0xfffff) | ((v & 0xfff) << 20);
 131         return 0;
 132 }
 133
 134 static int apply_r_riscv_pcrel_lo12_s_rela(struct module *me, u32 *location,
 135                                            Elf_Addr v)
 136 {
 137         /*
 138          * v is the lo12 value to fill. It is calculated before calling this
 139          * handler.
 140          */
 141         u32 imm11_5 = (v & 0xfe0) << (31 - 11);
 142         u32 imm4_0 = (v & 0x1f) << (11 - 4);
 143
 144         *location = (*location & 0x1fff07f) | imm11_5 | imm4_0;
 145         return 0;
 146 }
 147
 148 static int apply_r_riscv_hi20_rela(struct module *me, u32 *location,
 149                                    Elf_Addr v)
 150 {
 151         s32 hi20;
 152
 153         if (IS_ENABLED(CONFIG_CMODEL_MEDLOW)) {
 154                 pr_err(
 155                   "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
 156                   me->name, (long long)v, location);
 157                 return -EINVAL;
 158         }
 159
 160         hi20 = ((s32)v + 0x800) & 0xfffff000;
 161         *location = (*location & 0xfff) | hi20;
 162         return 0;
 163 }
 164
 165 static int apply_r_riscv_lo12_i_rela(struct module *me, u32 *location,
 166                                      Elf_Addr v)
 167 {
 168         /* Skip medlow checking because of filtering by HI20 already */
 169         s32 hi20 = ((s32)v + 0x800) & 0xfffff000;
 170         s32 lo12 = ((s32)v - hi20);
 171         *location = (*location & 0xfffff) | ((lo12 & 0xfff) << 20);
 172         return 0;
 173 }
 174
 175 static int apply_r_riscv_lo12_s_rela(struct module *me, u32 *location,
 176                                      Elf_Addr v)
 177 {
 178         /* Skip medlow checking because of filtering by HI20 already */
 179         s32 hi20 = ((s32)v + 0x800) & 0xfffff000;
 180         s32 lo12 = ((s32)v - hi20);
 181         u32 imm11_5 = (lo12 & 0xfe0) << (31 - 11);
 182         u32 imm4_0 = (lo12 & 0x1f) << (11 - 4);
 183         *location = (*location & 0x1fff07f) | imm11_5 | imm4_0;
 184         return 0;
 185 }
 186
 187 static int apply_r_riscv_got_hi20_rela(struct module *me, u32 *location,
 188                                        Elf_Addr v)
 189 {
 190         ptrdiff_t offset = (void *)v - (void *)location;
 191         s32 hi20;
 192
 193         /* Always emit the got entry */
 194         if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) {
 195                 offset = module_emit_got_entry(me, v);
 196                 offset = (void *)offset - (void *)location;
 197         } else {
 198                 pr_err(
 199                   "%s: can not generate the GOT entry for symbol = %016llx from PC = %p\n",
 200                   me->name, (long long)v, location);
 201                 return -EINVAL;
 202         }
 203
 204         hi20 = (offset + 0x800) & 0xfffff000;
 205         *location = (*location & 0xfff) | hi20;
 206         return 0;
 207 }
 208
 209 static int apply_r_riscv_call_plt_rela(struct module *me, u32 *location,
 210                                        Elf_Addr v)
 211 {
 212         ptrdiff_t offset = (void *)v - (void *)location;
 213         u32 hi20, lo12;
 214
 215         if (!riscv_insn_valid_32bit_offset(offset)) {
 216                 /* Only emit the plt entry if offset over 32-bit range */
 217                 if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) {
 218                         offset = module_emit_plt_entry(me, v);
 219                         offset = (void *)offset - (void *)location;
 220                 } else {
 221                         pr_err(
 222                           "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
 223                           me->name, (long long)v, location);
 224                         return -EINVAL;
 225                 }
 226         }
 227
 228         hi20 = (offset + 0x800) & 0xfffff000;
 229         lo12 = (offset - hi20) & 0xfff;
 230         *location = (*location & 0xfff) | hi20;
 231         *(location + 1) = (*(location + 1) & 0xfffff) | (lo12 << 20);
 232         return 0;
 233 }
 234
 235 static int apply_r_riscv_call_rela(struct module *me, u32 *location,
 236                                    Elf_Addr v)
 237 {
 238         ptrdiff_t offset = (void *)v - (void *)location;
 239         u32 hi20, lo12;
 240
 241         if (!riscv_insn_valid_32bit_offset(offset)) {
 242                 pr_err(
 243                   "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
 244                   me->name, (long long)v, location);
 245                 return -EINVAL;
 246         }
 247
 248         hi20 = (offset + 0x800) & 0xfffff000;
 249         lo12 = (offset - hi20) & 0xfff;
 250         *location = (*location & 0xfff) | hi20;
 251         *(location + 1) = (*(location + 1) & 0xfffff) | (lo12 << 20);
 252         return 0;
 253 }
 254
 255 static int apply_r_riscv_relax_rela(struct module *me, u32 *location,
 256                                     Elf_Addr v)
 257 {
 258         return 0;
 259 }
 260
 261 static int apply_r_riscv_align_rela(struct module *me, u32 *location,
 262                                     Elf_Addr v)
 263 {
 264         pr_err(
 265           "%s: The unexpected relocation type 'R_RISCV_ALIGN' from PC = %p\n",
 266           me->name, location);
 267         return -EINVAL;
 268 }
 269
 270 static int apply_r_riscv_add32_rela(struct module *me, u32 *location,
 271                                     Elf_Addr v)
 272 {
 273         *(u32 *)location += (u32)v;
 274         return 0;
 275 }
 276
 277 static int apply_r_riscv_sub32_rela(struct module *me, u32 *location,
 278                                     Elf_Addr v)
 279 {
 280         *(u32 *)location -= (u32)v;
 281         return 0;
 282 }
 283
 284 static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
 285                                 Elf_Addr v) = {
 286         [R_RISCV_32]                    = apply_r_riscv_32_rela,
 287         [R_RISCV_64]                    = apply_r_riscv_64_rela,
 288         [R_RISCV_BRANCH]                = apply_r_riscv_branch_rela,
 289         [R_RISCV_JAL]                   = apply_r_riscv_jal_rela,
 290         [R_RISCV_RVC_BRANCH]            = apply_r_riscv_rcv_branch_rela,
 291         [R_RISCV_RVC_JUMP]              = apply_r_riscv_rvc_jump_rela,
 292         [R_RISCV_PCREL_HI20]            = apply_r_riscv_pcrel_hi20_rela,
 293         [R_RISCV_PCREL_LO12_I]          = apply_r_riscv_pcrel_lo12_i_rela,
 294         [R_RISCV_PCREL_LO12_S]          = apply_r_riscv_pcrel_lo12_s_rela,
 295         [R_RISCV_HI20]                  = apply_r_riscv_hi20_rela,
 296         [R_RISCV_LO12_I]                = apply_r_riscv_lo12_i_rela,
 297         [R_RISCV_LO12_S]                = apply_r_riscv_lo12_s_rela,
 298         [R_RISCV_GOT_HI20]              = apply_r_riscv_got_hi20_rela,
 299         [R_RISCV_CALL_PLT]              = apply_r_riscv_call_plt_rela,
 300         [R_RISCV_CALL]                  = apply_r_riscv_call_rela,
 301         [R_RISCV_RELAX]                 = apply_r_riscv_relax_rela,
 302         [R_RISCV_ALIGN]                 = apply_r_riscv_align_rela,
 303         [R_RISCV_ADD32]                 = apply_r_riscv_add32_rela,
 304         [R_RISCV_SUB32]                 = apply_r_riscv_sub32_rela,
 305 };
 306
 307 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
 308                        unsigned int symindex, unsigned int relsec,
 309                        struct module *me)
 310 {
 311         Elf_Rela *rel = (void *) sechdrs[relsec].sh_addr;
 312         int (*handler)(struct module *me, u32 *location, Elf_Addr v);
 313         Elf_Sym *sym;
 314         u32 *location;
 315         unsigned int i, type;
 316         Elf_Addr v;
 317         int res;
 318
 319         pr_debug("Applying relocate section %u to %u\n", relsec,
 320                sechdrs[relsec].sh_info);
 321
 322         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 323                 /* This is where to make the change */
 324                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 325                         + rel[i].r_offset;
 326                 /* This is the symbol it is referring to */
 327                 sym = (Elf_Sym *)sechdrs[symindex].sh_addr
 328                         + ELF_RISCV_R_SYM(rel[i].r_info);
 329                 if (IS_ERR_VALUE(sym->st_value)) {
 330                         /* Ignore unresolved weak symbol */
 331                         if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
 332                                 continue;
 333                         pr_warning("%s: Unknown symbol %s\n",
 334                                    me->name, strtab + sym->st_name);
 335                         return -ENOENT;
 336                 }
 337
 338                 type = ELF_RISCV_R_TYPE(rel[i].r_info);
 339
 340                 if (type < ARRAY_SIZE(reloc_handlers_rela))
 341                         handler = reloc_handlers_rela[type];
 342                 else
 343                         handler = NULL;
 344
 345                 if (!handler) {
 346                         pr_err("%s: Unknown relocation type %u\n",
 347                                me->name, type);
 348                         return -EINVAL;
 349                 }
 350
 351                 v = sym->st_value + rel[i].r_addend;
 352
 353                 if (type == R_RISCV_PCREL_LO12_I || type == R_RISCV_PCREL_LO12_S) {
 354                         unsigned int j;
 355
 356                         for (j = 0; j < sechdrs[relsec].sh_size / sizeof(*rel); j++) {
 357                                 unsigned long hi20_loc =
 358                                         sechdrs[sechdrs[relsec].sh_info].sh_addr
 359                                         + rel[j].r_offset;
 360                                 u32 hi20_type = ELF_RISCV_R_TYPE(rel[j].r_info);
 361
 362                                 /* Find the corresponding HI20 relocation entry */
 363                                 if (hi20_loc == sym->st_value
 364                                     && (hi20_type == R_RISCV_PCREL_HI20
 365                                         || hi20_type == R_RISCV_GOT_HI20)) {
 366                                         s32 hi20, lo12;
 367                                         Elf_Sym *hi20_sym =
 368                                                 (Elf_Sym *)sechdrs[symindex].sh_addr
 369                                                 + ELF_RISCV_R_SYM(rel[j].r_info);
 370                                         unsigned long hi20_sym_val =
 371                                                 hi20_sym->st_value
 372                                                 + rel[j].r_addend;
 373
 374                                         /* Calculate lo12 */
 375                                         size_t offset = hi20_sym_val - hi20_loc;
 376                                         if (IS_ENABLED(CONFIG_MODULE_SECTIONS)
 377                                             && hi20_type == R_RISCV_GOT_HI20) {
 378                                                 offset = module_emit_got_entry(
 379                                                          me, hi20_sym_val);
 380                                                 offset = offset - hi20_loc;
 381                                         }
 382                                         hi20 = (offset + 0x800) & 0xfffff000;
 383                                         lo12 = offset - hi20;
 384                                         v = lo12;
 385
 386                                         break;
 387                                 }
 388                         }
 389                         if (j == sechdrs[relsec].sh_size / sizeof(*rel)) {
 390                                 pr_err(
 391                                   "%s: Can not find HI20 relocation information\n",
 392                                   me->name);
 393                                 return -EINVAL;
 394                         }
 395                 }
 396
 397                 res = handler(me, location, v);
 398                 if (res)
 399                         return res;
 400         }
 401
 402         return 0;
 403 }
 404
 405 #if defined(CONFIG_MMU) && defined(CONFIG_64BIT)
 406 #define VMALLOC_MODULE_START \
 407          max(PFN_ALIGN((unsigned long)&_end - SZ_2G), VMALLOC_START)
 408 void *module_alloc(unsigned long size)
 409 {
 410         return __vmalloc_node_range(size, 1, VMALLOC_MODULE_START,
 411                                     VMALLOC_END, GFP_KERNEL,
 412                                     PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
 413                                     __builtin_return_address(0));
 414 }
 415 #endif