| 1 | /* Linux bpf specific support for 64-bit ELF |
| 2 | Copyright (C) 2019 Free Software Foundation, Inc. |
| 3 | Contributed by Oracle Inc. |
| 4 | |
| 5 | This file is part of BFD, the Binary File Descriptor library. |
| 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 as published by |
| 9 | the Free Software Foundation; either version 3 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program; if not, write to the Free Software |
| 19 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| 20 | MA 02110-1301, USA. */ |
| 21 | |
| 22 | #include "sysdep.h" |
| 23 | #include "bfd.h" |
| 24 | #include "libbfd.h" |
| 25 | #include "elf-bfd.h" |
| 26 | #include "elf/bpf.h" |
| 27 | #include "libiberty.h" |
| 28 | |
| 29 | /* In case we're on a 32-bit machine, construct a 64-bit "-1" value. */ |
| 30 | #define MINUS_ONE (~ (bfd_vma) 0) |
| 31 | |
| 32 | #define BASEADDR(SEC) ((SEC)->output_section->vma + (SEC)->output_offset) |
| 33 | |
| 34 | /* Handler for PC-relative relocations, which must be handled in |
| 35 | 64-bit words. */ |
| 36 | |
| 37 | static bfd_reloc_status_type |
| 38 | bpf_elf_insn_disp_reloc (bfd *abfd, |
| 39 | arelent *reloc_entry, |
| 40 | asymbol *symbol, |
| 41 | void *data, |
| 42 | asection *input_section, |
| 43 | bfd *output_bfd, |
| 44 | char **error_message ATTRIBUTE_UNUSED) |
| 45 | { |
| 46 | bfd_signed_vma relocation; |
| 47 | bfd_signed_vma addend; |
| 48 | reloc_howto_type *howto = reloc_entry->howto; |
| 49 | |
| 50 | /* This part is from bfd_elf_generic_reloc. */ |
| 51 | if (output_bfd != NULL |
| 52 | && (symbol->flags & BSF_SECTION_SYM) == 0 |
| 53 | && (! reloc_entry->howto->partial_inplace |
| 54 | || reloc_entry->addend == 0)) |
| 55 | { |
| 56 | reloc_entry->address += input_section->output_offset; |
| 57 | return bfd_reloc_ok; |
| 58 | } |
| 59 | |
| 60 | /* This works because partial_inplace is FALSE. */ |
| 61 | if (output_bfd != NULL) |
| 62 | return bfd_reloc_continue; |
| 63 | |
| 64 | if (reloc_entry->address > bfd_get_section_limit (abfd, input_section)) |
| 65 | return bfd_reloc_outofrange; |
| 66 | |
| 67 | relocation = (symbol->value |
| 68 | + symbol->section->output_section->vma |
| 69 | + symbol->section->output_offset); |
| 70 | /* Make it PC relative. */ |
| 71 | relocation -= (input_section->output_section->vma |
| 72 | + input_section->output_offset); |
| 73 | relocation -= reloc_entry->address; |
| 74 | /* Make it 64-bit words. */ |
| 75 | relocation = relocation / 8; |
| 76 | |
| 77 | /* Get the addend from the instruction and apply it. */ |
| 78 | switch (howto->bitsize) |
| 79 | { |
| 80 | default: |
| 81 | abort (); |
| 82 | break; |
| 83 | case 16: |
| 84 | addend = bfd_get_16 (abfd, (bfd_byte *) data + reloc_entry->address + 2); |
| 85 | break; |
| 86 | case 32: |
| 87 | addend = bfd_get_32 (abfd, (bfd_byte *) data + reloc_entry->address + 4); |
| 88 | break; |
| 89 | } |
| 90 | |
| 91 | if ((addend & (((~howto->src_mask) >> 1) & howto->src_mask)) != 0) |
| 92 | addend -= (((~howto->src_mask) >> 1) & howto->src_mask) << 1; |
| 93 | relocation += addend; |
| 94 | |
| 95 | /* Write out the relocated value. */ |
| 96 | switch (howto->bitsize) |
| 97 | { |
| 98 | default: |
| 99 | abort (); |
| 100 | break; |
| 101 | case 16: |
| 102 | bfd_put_16 (abfd, relocation, (bfd_byte *) data + reloc_entry->address + 2); |
| 103 | break; |
| 104 | case 32: |
| 105 | bfd_put_32 (abfd, relocation, (bfd_byte *) data + reloc_entry->address + 4); |
| 106 | break; |
| 107 | } |
| 108 | |
| 109 | /* Check for overflow. */ |
| 110 | if (howto->complain_on_overflow == complain_overflow_signed) |
| 111 | { |
| 112 | bfd_signed_vma reloc_signed_max = (1 << (howto->bitsize - 1)) - 1; |
| 113 | bfd_signed_vma reloc_signed_min = ~reloc_signed_max; |
| 114 | |
| 115 | if (relocation > reloc_signed_max || relocation < reloc_signed_min) |
| 116 | return bfd_reloc_overflow; |
| 117 | } |
| 118 | else |
| 119 | abort(); |
| 120 | |
| 121 | return bfd_reloc_ok; |
| 122 | } |
| 123 | |
| 124 | /* Relocation tables. */ |
| 125 | static reloc_howto_type bpf_elf_howto_table [] = |
| 126 | { |
| 127 | /* This reloc does nothing. */ |
| 128 | HOWTO (R_BPF_NONE, /* type */ |
| 129 | 0, /* rightshift */ |
| 130 | 3, /* size (0 = byte, 1 = short, 2 = long) */ |
| 131 | 0, /* bitsize */ |
| 132 | FALSE, /* pc_relative */ |
| 133 | 0, /* bitpos */ |
| 134 | complain_overflow_dont, /* complain_on_overflow */ |
| 135 | bfd_elf_generic_reloc, /* special_function */ |
| 136 | "R_BPF_NONE", /* name */ |
| 137 | FALSE, /* partial_inplace */ |
| 138 | 0, /* src_mask */ |
| 139 | 0, /* dst_mask */ |
| 140 | FALSE), /* pcrel_offset */ |
| 141 | |
| 142 | /* 64-immediate in LDDW instruction. */ |
| 143 | HOWTO (R_BPF_INSN_64, /* type */ |
| 144 | 0, /* rightshift */ |
| 145 | 4, /* size (0 = byte, 1 = short, 2 = long) */ |
| 146 | 64, /* bitsize */ |
| 147 | FALSE, /* pc_relative */ |
| 148 | 0, /* bitpos */ |
| 149 | complain_overflow_signed, /* complain_on_overflow */ |
| 150 | bfd_elf_generic_reloc, /* special_function */ |
| 151 | "R_BPF_INSN_64", /* name */ |
| 152 | FALSE, /* partial_inplace */ |
| 153 | 0, /* src_mask */ |
| 154 | MINUS_ONE, /* dst_mask */ |
| 155 | TRUE), /* pcrel_offset */ |
| 156 | |
| 157 | /* 32-immediate in LDDW instruction. */ |
| 158 | HOWTO (R_BPF_INSN_32, /* type */ |
| 159 | 0, /* rightshift */ |
| 160 | 2, /* size (0 = byte, 1 = short, 2 = long) */ |
| 161 | 32, /* bitsize */ |
| 162 | FALSE, /* pc_relative */ |
| 163 | 0, /* bitpos */ |
| 164 | complain_overflow_signed, /* complain_on_overflow */ |
| 165 | bfd_elf_generic_reloc, /* special_function */ |
| 166 | "R_BPF_INSN_32", /* name */ |
| 167 | FALSE, /* partial_inplace */ |
| 168 | 0, /* src_mask */ |
| 169 | 0xffffffff, /* dst_mask */ |
| 170 | TRUE), /* pcrel_offset */ |
| 171 | |
| 172 | /* 16-bit offsets in instructions. */ |
| 173 | HOWTO (R_BPF_INSN_16, /* type */ |
| 174 | 0, /* rightshift */ |
| 175 | 1, /* size (0 = byte, 1 = short, 2 = long) */ |
| 176 | 16, /* bitsize */ |
| 177 | FALSE, /* pc_relative */ |
| 178 | 0, /* bitpos */ |
| 179 | complain_overflow_signed, /* complain_on_overflow */ |
| 180 | bfd_elf_generic_reloc, /* special_function */ |
| 181 | "R_BPF_INSN_16", /* name */ |
| 182 | FALSE, /* partial_inplace */ |
| 183 | 0, /* src_mask */ |
| 184 | 0x0000ffff, /* dst_mask */ |
| 185 | TRUE), /* pcrel_offset */ |
| 186 | |
| 187 | /* 16-bit PC-relative address in jump instructions. */ |
| 188 | HOWTO (R_BPF_INSN_DISP16, /* type */ |
| 189 | 0, /* rightshift */ |
| 190 | 1, /* size (0 = byte, 1 = short, 2 = long) */ |
| 191 | 16, /* bitsize */ |
| 192 | TRUE, /* pc_relative */ |
| 193 | 32, /* bitpos */ |
| 194 | complain_overflow_signed, /* complain_on_overflow */ |
| 195 | bpf_elf_insn_disp_reloc, /* special_function */ |
| 196 | "R_BPF_INSN_DISP16", /* name */ |
| 197 | FALSE, /* partial_inplace */ |
| 198 | 0xffff, /* src_mask */ |
| 199 | 0xffff, /* dst_mask */ |
| 200 | TRUE), /* pcrel_offset */ |
| 201 | |
| 202 | HOWTO (R_BPF_DATA_8_PCREL, |
| 203 | 0, /* rightshift */ |
| 204 | 0, /* size (0 = byte, 1 = short, 2 = long) */ |
| 205 | 8, /* bitsize */ |
| 206 | TRUE, /* pc_relative */ |
| 207 | 0, /* bitpos */ |
| 208 | complain_overflow_signed, /* complain_on_overflow */ |
| 209 | bfd_elf_generic_reloc, /* special_function */ |
| 210 | "R_BPF_8_PCREL", /* name */ |
| 211 | FALSE, /* partial_inplace */ |
| 212 | 0, /* src_mask */ |
| 213 | 0xff, /* dst_mask */ |
| 214 | TRUE), /* pcrel_offset */ |
| 215 | |
| 216 | HOWTO (R_BPF_DATA_16_PCREL, |
| 217 | 0, /* rightshift */ |
| 218 | 1, /* size (0 = byte, 1 = short, 2 = long) */ |
| 219 | 16, /* bitsize */ |
| 220 | TRUE, /* pc_relative */ |
| 221 | 0, /* bitpos */ |
| 222 | complain_overflow_signed, /* complain_on_overflow */ |
| 223 | bfd_elf_generic_reloc, /* special_function */ |
| 224 | "R_BPF_16_PCREL", /* name */ |
| 225 | FALSE, /* partial_inplace */ |
| 226 | 0, /* src_mask */ |
| 227 | 0xffff, /* dst_mask */ |
| 228 | TRUE), /* pcrel_offset */ |
| 229 | |
| 230 | HOWTO (R_BPF_DATA_32_PCREL, |
| 231 | 0, /* rightshift */ |
| 232 | 2, /* size (0 = byte, 1 = short, 2 = long) */ |
| 233 | 32, /* bitsize */ |
| 234 | TRUE, /* pc_relative */ |
| 235 | 0, /* bitpos */ |
| 236 | complain_overflow_signed, /* complain_on_overflow */ |
| 237 | bfd_elf_generic_reloc, /* special_function */ |
| 238 | "R_BPF_32_PCREL", /* name */ |
| 239 | FALSE, /* partial_inplace */ |
| 240 | 0, /* src_mask */ |
| 241 | 0xffffffff, /* dst_mask */ |
| 242 | TRUE), /* pcrel_offset */ |
| 243 | |
| 244 | HOWTO (R_BPF_DATA_8, |
| 245 | 0, /* rightshift */ |
| 246 | 0, /* size (0 = byte, 1 = short, 2 = long) */ |
| 247 | 8, /* bitsize */ |
| 248 | FALSE, /* pc_relative */ |
| 249 | 0, /* bitpos */ |
| 250 | complain_overflow_unsigned, /* complain_on_overflow */ |
| 251 | bfd_elf_generic_reloc, /* special_function */ |
| 252 | "R_BPF_DATA_8", /* name */ |
| 253 | FALSE, /* partial_inplace */ |
| 254 | 0, /* src_mask */ |
| 255 | 0xff, /* dst_mask */ |
| 256 | FALSE), /* pcrel_offset */ |
| 257 | |
| 258 | HOWTO (R_BPF_DATA_16, |
| 259 | 0, /* rightshift */ |
| 260 | 1, /* size (0 = byte, 1 = short, 2 = long) */ |
| 261 | 16, /* bitsize */ |
| 262 | FALSE, /* pc_relative */ |
| 263 | 0, /* bitpos */ |
| 264 | complain_overflow_unsigned, /* complain_on_overflow */ |
| 265 | bfd_elf_generic_reloc, /* special_function */ |
| 266 | "R_BPF_DATA_16", /* name */ |
| 267 | FALSE, /* partial_inplace */ |
| 268 | 0, /* src_mask */ |
| 269 | 0xffff, /* dst_mask */ |
| 270 | FALSE), /* pcrel_offset */ |
| 271 | |
| 272 | /* 32-bit PC-relative address in call instructions. */ |
| 273 | HOWTO (R_BPF_INSN_DISP32, /* type */ |
| 274 | 0, /* rightshift */ |
| 275 | 2, /* size (0 = byte, 1 = short, 2 = long) */ |
| 276 | 32, /* bitsize */ |
| 277 | TRUE, /* pc_relative */ |
| 278 | 0, /* bitpos */ |
| 279 | complain_overflow_signed, /* complain_on_overflow */ |
| 280 | bpf_elf_insn_disp_reloc, /* special_function */ |
| 281 | "R_BPF_INSN_DISP32", /* name */ |
| 282 | FALSE, /* partial_inplace */ |
| 283 | 0xffffffff, /* src_mask */ |
| 284 | 0xffffffff, /* dst_mask */ |
| 285 | TRUE), /* pcrel_offset */ |
| 286 | |
| 287 | /* 32-bit data. */ |
| 288 | HOWTO (R_BPF_DATA_32, /* type */ |
| 289 | 0, /* rightshift */ |
| 290 | 2, /* size (0 = byte, 1 = short, 2 = long) */ |
| 291 | 32, /* bitsize */ |
| 292 | FALSE, /* pc_relative */ |
| 293 | 0, /* bitpos */ |
| 294 | complain_overflow_bitfield, /* complain_on_overflow */ |
| 295 | bfd_elf_generic_reloc, /* special_function */ |
| 296 | "R_BPF_DATA_32", /* name */ |
| 297 | FALSE, /* partial_inplace */ |
| 298 | 0, /* src_mask */ |
| 299 | 0xffffffff, /* dst_mask */ |
| 300 | TRUE), /* pcrel_offset */ |
| 301 | |
| 302 | /* 64-bit data. */ |
| 303 | HOWTO (R_BPF_DATA_64, /* type */ |
| 304 | 0, /* rightshift */ |
| 305 | 4, /* size (0 = byte, 1 = short, 2 = long) */ |
| 306 | 64, /* bitsize */ |
| 307 | FALSE, /* pc_relative */ |
| 308 | 0, /* bitpos */ |
| 309 | complain_overflow_bitfield, /* complain_on_overflow */ |
| 310 | bfd_elf_generic_reloc, /* special_function */ |
| 311 | "R_BPF_DATA_64", /* name */ |
| 312 | FALSE, /* partial_inplace */ |
| 313 | 0, /* src_mask */ |
| 314 | MINUS_ONE, /* dst_mask */ |
| 315 | TRUE), /* pcrel_offset */ |
| 316 | |
| 317 | HOWTO (R_BPF_DATA_64_PCREL, |
| 318 | 0, /* rightshift */ |
| 319 | 4, /* size (0 = byte, 1 = short, 2 = long) */ |
| 320 | 64, /* bitsize */ |
| 321 | TRUE, /* pc_relative */ |
| 322 | 0, /* bitpos */ |
| 323 | complain_overflow_signed, /* complain_on_overflow */ |
| 324 | bfd_elf_generic_reloc, /* special_function */ |
| 325 | "R_BPF_64_PCREL", /* name */ |
| 326 | FALSE, /* partial_inplace */ |
| 327 | 0, /* src_mask */ |
| 328 | MINUS_ONE, /* dst_mask */ |
| 329 | TRUE), /* pcrel_offset */ |
| 330 | }; |
| 331 | #undef AHOW |
| 332 | |
| 333 | /* Map BFD reloc types to bpf ELF reloc types. */ |
| 334 | |
| 335 | static reloc_howto_type * |
| 336 | bpf_reloc_type_lookup (bfd * abfd ATTRIBUTE_UNUSED, |
| 337 | bfd_reloc_code_real_type code) |
| 338 | { |
| 339 | /* Note that the bpf_elf_howto_table is indxed by the R_ |
| 340 | constants. Thus, the order that the howto records appear in the |
| 341 | table *must* match the order of the relocation types defined in |
| 342 | include/elf/bpf.h. */ |
| 343 | |
| 344 | switch (code) |
| 345 | { |
| 346 | case BFD_RELOC_NONE: |
| 347 | return &bpf_elf_howto_table[ (int) R_BPF_NONE]; |
| 348 | |
| 349 | case BFD_RELOC_8_PCREL: |
| 350 | return &bpf_elf_howto_table[ (int) R_BPF_DATA_8_PCREL]; |
| 351 | case BFD_RELOC_16_PCREL: |
| 352 | return &bpf_elf_howto_table[ (int) R_BPF_DATA_16_PCREL]; |
| 353 | case BFD_RELOC_32_PCREL: |
| 354 | return &bpf_elf_howto_table[ (int) R_BPF_DATA_32_PCREL]; |
| 355 | case BFD_RELOC_64_PCREL: |
| 356 | return &bpf_elf_howto_table[ (int) R_BPF_DATA_64_PCREL]; |
| 357 | |
| 358 | case BFD_RELOC_8: |
| 359 | return &bpf_elf_howto_table[ (int) R_BPF_DATA_8]; |
| 360 | case BFD_RELOC_16: |
| 361 | return &bpf_elf_howto_table[ (int) R_BPF_DATA_16]; |
| 362 | case BFD_RELOC_32: |
| 363 | return &bpf_elf_howto_table[ (int) R_BPF_DATA_32]; |
| 364 | case BFD_RELOC_64: |
| 365 | return &bpf_elf_howto_table[ (int) R_BPF_DATA_64]; |
| 366 | |
| 367 | case BFD_RELOC_BPF_64: |
| 368 | return &bpf_elf_howto_table[ (int) R_BPF_INSN_64]; |
| 369 | case BFD_RELOC_BPF_32: |
| 370 | return &bpf_elf_howto_table[ (int) R_BPF_INSN_32]; |
| 371 | case BFD_RELOC_BPF_16: |
| 372 | return &bpf_elf_howto_table[ (int) R_BPF_INSN_16]; |
| 373 | case BFD_RELOC_BPF_DISP16: |
| 374 | return &bpf_elf_howto_table[ (int) R_BPF_INSN_DISP16]; |
| 375 | case BFD_RELOC_BPF_DISP32: |
| 376 | return &bpf_elf_howto_table[ (int) R_BPF_INSN_DISP32]; |
| 377 | |
| 378 | default: |
| 379 | /* Pacify gcc -Wall. */ |
| 380 | return NULL; |
| 381 | } |
| 382 | return NULL; |
| 383 | } |
| 384 | |
| 385 | /* Map BFD reloc names to bpf ELF reloc names. */ |
| 386 | |
| 387 | static reloc_howto_type * |
| 388 | bpf_reloc_name_lookup (bfd *abfd ATTRIBUTE_UNUSED, const char *r_name) |
| 389 | { |
| 390 | unsigned int i; |
| 391 | |
| 392 | for (i = 0; i < ARRAY_SIZE (bpf_elf_howto_table); i++) |
| 393 | if (bpf_elf_howto_table[i].name != NULL |
| 394 | && strcasecmp (bpf_elf_howto_table[i].name, r_name) == 0) |
| 395 | return &bpf_elf_howto_table[i]; |
| 396 | |
| 397 | return NULL; |
| 398 | } |
| 399 | |
| 400 | /* Set the howto pointer for a bpf reloc. */ |
| 401 | |
| 402 | static bfd_boolean |
| 403 | bpf_info_to_howto (bfd *abfd, arelent *bfd_reloc, |
| 404 | Elf_Internal_Rela *elf_reloc) |
| 405 | { |
| 406 | unsigned int r_type; |
| 407 | |
| 408 | r_type = ELF64_R_TYPE (elf_reloc->r_info); |
| 409 | if (r_type >= (unsigned int) R_BPF_max) |
| 410 | { |
| 411 | /* xgettext:c-format */ |
| 412 | _bfd_error_handler (_("%pB: unsupported relocation type %#x"), |
| 413 | abfd, r_type); |
| 414 | bfd_set_error (bfd_error_bad_value); |
| 415 | return FALSE; |
| 416 | } |
| 417 | |
| 418 | bfd_reloc->howto = &bpf_elf_howto_table [r_type]; |
| 419 | return TRUE; |
| 420 | } |
| 421 | |
| 422 | /* Merge backend specific data from an object file to the output |
| 423 | object file when linking. */ |
| 424 | |
| 425 | static bfd_boolean |
| 426 | elf64_bpf_merge_private_bfd_data (bfd *ibfd, struct bfd_link_info *info) |
| 427 | { |
| 428 | /* Check if we have the same endianness. */ |
| 429 | if (! _bfd_generic_verify_endian_match (ibfd, info)) |
| 430 | return FALSE; |
| 431 | |
| 432 | return TRUE; |
| 433 | } |
| 434 | |
| 435 | /* The macros below configure the architecture. */ |
| 436 | |
| 437 | #define TARGET_LITTLE_SYM bpf_elf64_le_vec |
| 438 | #define TARGET_LITTLE_NAME "elf64-bpfle" |
| 439 | |
| 440 | #define TARGET_BIG_SYM bpf_elf64_be_vec |
| 441 | #define TARGET_BIG_NAME "elf64-bpfbe" |
| 442 | |
| 443 | #define ELF_ARCH bfd_arch_bpf |
| 444 | #define ELF_MACHINE_CODE EM_BPF |
| 445 | |
| 446 | #define ELF_MAXPAGESIZE 0x100000 |
| 447 | |
| 448 | #define elf_info_to_howto_rel bpf_info_to_howto |
| 449 | #define elf_info_to_howto bpf_info_to_howto |
| 450 | |
| 451 | #define elf_backend_may_use_rel_p 1 |
| 452 | #define elf_backend_may_use_rela_p 0 |
| 453 | #define elf_backend_default_use_rela_p 0 |
| 454 | |
| 455 | #define elf_backend_can_gc_sections 0 |
| 456 | |
| 457 | #define elf_symbol_leading_char '_' |
| 458 | #define bfd_elf64_bfd_reloc_type_lookup bpf_reloc_type_lookup |
| 459 | #define bfd_elf64_bfd_reloc_name_lookup bpf_reloc_name_lookup |
| 460 | |
| 461 | #define bfd_elf64_bfd_merge_private_bfd_data elf64_bpf_merge_private_bfd_data |
| 462 | |
| 463 | #include "elf64-target.h" |