arch/riscv/kernel/module.c

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