Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/mips/mips/elf_machdep.c
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1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright 1996-1998 John D. Polstra. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * 27 * from: src/sys/i386/i386/elf_machdep.c,v 1.20 2004/08/11 02:35:05 marcel 28 */ 29 30 #include <sys/cdefs.h> 31 __FBSDID("$FreeBSD$"); 32 33 #include <sys/param.h> 34 #include <sys/kernel.h> 35 #include <sys/systm.h> 36 #include <sys/exec.h> 37 #include <sys/imgact.h> 38 #include <sys/linker.h> 39 #include <sys/sysent.h> 40 #include <sys/imgact_elf.h> 41 #include <sys/proc.h> 42 #include <sys/syscall.h> 43 #include <sys/signalvar.h> 44 #include <sys/vnode.h> 45 46 #include <vm/vm.h> 47 #include <vm/pmap.h> 48 #include <vm/vm_param.h> 49 50 #include <machine/elf.h> 51 #include <machine/md_var.h> 52 #include <machine/cache.h> 53 54 #ifdef __mips_n64 55 struct sysentvec elf64_freebsd_sysvec = { 56 .sv_size = SYS_MAXSYSCALL, 57 .sv_table = sysent, 58 .sv_mask = 0, 59 .sv_errsize = 0, 60 .sv_errtbl = NULL, 61 .sv_transtrap = NULL, 62 .sv_fixup = __elfN(freebsd_fixup), 63 .sv_sendsig = sendsig, 64 .sv_sigcode = sigcode, 65 .sv_szsigcode = &szsigcode, 66 .sv_name = "FreeBSD ELF64", 67 .sv_coredump = __elfN(coredump), 68 .sv_imgact_try = NULL, 69 .sv_minsigstksz = MINSIGSTKSZ, 70 .sv_minuser = VM_MIN_ADDRESS, 71 .sv_maxuser = VM_MAXUSER_ADDRESS, 72 .sv_usrstack = USRSTACK, 73 .sv_psstrings = PS_STRINGS, 74 .sv_stackprot = VM_PROT_ALL, 75 .sv_copyout_strings = exec_copyout_strings, 76 .sv_setregs = exec_setregs, 77 .sv_fixlimit = NULL, 78 .sv_maxssiz = NULL, 79 .sv_flags = SV_ABI_FREEBSD | SV_LP64 | SV_ASLR, 80 .sv_set_syscall_retval = cpu_set_syscall_retval, 81 .sv_fetch_syscall_args = cpu_fetch_syscall_args, 82 .sv_syscallnames = syscallnames, 83 .sv_schedtail = NULL, 84 .sv_thread_detach = NULL, 85 .sv_trap = NULL, 86 }; 87 88 static Elf64_Brandinfo freebsd_brand_info = { 89 .brand = ELFOSABI_FREEBSD, 90 .machine = EM_MIPS, 91 .compat_3_brand = "FreeBSD", 92 .emul_path = NULL, 93 .interp_path = "/libexec/ld-elf.so.1", 94 .sysvec = &elf64_freebsd_sysvec, 95 .interp_newpath = NULL, 96 .brand_note = &elf64_freebsd_brandnote, 97 .flags = BI_CAN_EXEC_DYN | BI_BRAND_NOTE 98 }; 99 100 SYSINIT(elf64, SI_SUB_EXEC, SI_ORDER_ANY, 101 (sysinit_cfunc_t) elf64_insert_brand_entry, 102 &freebsd_brand_info); 103 104 void 105 elf64_dump_thread(struct thread *td __unused, void *dst __unused, 106 size_t *off __unused) 107 { 108 } 109 #else 110 struct sysentvec elf32_freebsd_sysvec = { 111 .sv_size = SYS_MAXSYSCALL, 112 .sv_table = sysent, 113 .sv_mask = 0, 114 .sv_errsize = 0, 115 .sv_errtbl = NULL, 116 .sv_transtrap = NULL, 117 .sv_fixup = __elfN(freebsd_fixup), 118 .sv_sendsig = sendsig, 119 .sv_sigcode = sigcode, 120 .sv_szsigcode = &szsigcode, 121 .sv_name = "FreeBSD ELF32", 122 .sv_coredump = __elfN(coredump), 123 .sv_imgact_try = NULL, 124 .sv_minsigstksz = MINSIGSTKSZ, 125 .sv_minuser = VM_MIN_ADDRESS, 126 .sv_maxuser = VM_MAXUSER_ADDRESS, 127 .sv_usrstack = USRSTACK, 128 .sv_psstrings = PS_STRINGS, 129 .sv_stackprot = VM_PROT_ALL, 130 .sv_copyout_strings = exec_copyout_strings, 131 .sv_setregs = exec_setregs, 132 .sv_fixlimit = NULL, 133 .sv_maxssiz = NULL, 134 .sv_flags = SV_ABI_FREEBSD | SV_ILP32 | SV_ASLR, 135 .sv_set_syscall_retval = cpu_set_syscall_retval, 136 .sv_fetch_syscall_args = cpu_fetch_syscall_args, 137 .sv_syscallnames = syscallnames, 138 .sv_schedtail = NULL, 139 .sv_thread_detach = NULL, 140 .sv_trap = NULL, 141 }; 142 143 static Elf32_Brandinfo freebsd_brand_info = { 144 .brand = ELFOSABI_FREEBSD, 145 .machine = EM_MIPS, 146 .compat_3_brand = "FreeBSD", 147 .emul_path = NULL, 148 .interp_path = "/libexec/ld-elf.so.1", 149 .sysvec = &elf32_freebsd_sysvec, 150 .interp_newpath = NULL, 151 .brand_note = &elf32_freebsd_brandnote, 152 .flags = BI_CAN_EXEC_DYN | BI_BRAND_NOTE 153 }; 154 155 SYSINIT(elf32, SI_SUB_EXEC, SI_ORDER_FIRST, 156 (sysinit_cfunc_t) elf32_insert_brand_entry, 157 &freebsd_brand_info); 158 159 void 160 elf32_dump_thread(struct thread *td __unused, void *dst __unused, 161 size_t *off __unused) 162 { 163 } 164 #endif 165 166 /* 167 * The following MIPS relocation code for tracking multiple 168 * consecutive HI32/LO32 entries is because of the following: 169 * 170 * https://dmz-portal.mips.com/wiki/MIPS_relocation_types 171 * 172 * === 173 * 174 * + R_MIPS_HI16 175 * 176 * An R_MIPS_HI16 must be followed eventually by an associated R_MIPS_LO16 177 * relocation record in the same SHT_REL section. The contents of the two 178 * fields to be relocated are combined to form a full 32-bit addend AHL. 179 * An R_MIPS_LO16 entry which does not immediately follow a R_MIPS_HI16 is 180 * combined with the most recent one encountered, i.e. multiple R_MIPS_LO16 181 * entries may be associated with a single R_MIPS_HI16. Use of these 182 * relocation types in a SHT_REL section is discouraged and may be 183 * forbidden to avoid this complication. 184 * 185 * A GNU extension allows multiple R_MIPS_HI16 records to share the same 186 * R_MIPS_LO16 relocation record(s). The association works like this within 187 * a single relocation section: 188 * 189 * + From the beginning of the section moving to the end of the section, 190 * until R_MIPS_LO16 is not found each found R_MIPS_HI16 relocation will 191 * be associated with the first R_MIPS_LO16. 192 * 193 * + Until another R_MIPS_HI16 record is found all found R_MIPS_LO16 194 * relocations found are associated with the last R_MIPS_HI16. 195 * 196 * === 197 * 198 * This is so gcc can do dead code detection/removal without having to 199 * generate HI/LO pairs even if one of them would be deleted. 200 * 201 * So, the summary is: 202 * 203 * + A HI16 entry must occur before any LO16 entries; 204 * + Multiple consecutive HI16 RELA entries need to be buffered until the 205 * first LO16 RELA entry occurs - and then all HI16 RELA relocations use 206 * the offset in the LOW16 RELA for calculating their offsets; 207 * + The last HI16 RELA entry before a LO16 RELA entry is used (the AHL) 208 * for the first subsequent LO16 calculation; 209 * + If multiple consecutive LO16 RELA entries occur, only the first 210 * LO16 RELA entry triggers an update of buffered HI16 RELA entries; 211 * any subsequent LO16 RELA entry before another HI16 RELA entry will 212 * not cause any further updates to the HI16 RELA entries. 213 * 214 * Additionally, flush out any outstanding HI16 entries that don't have 215 * a LO16 entry in case some garbage entries are left in the file. 216 */ 217 218 struct mips_tmp_reloc; 219 struct mips_tmp_reloc { 220 struct mips_tmp_reloc *next; 221 222 Elf_Addr ahl; 223 Elf32_Addr *where_hi16; 224 }; 225 226 static struct mips_tmp_reloc *ml = NULL; 227 228 /* 229 * Add a temporary relocation (ie, a HI16 reloc type.) 230 */ 231 static int 232 mips_tmp_reloc_add(Elf_Addr ahl, Elf32_Addr *where_hi16) 233 { 234 struct mips_tmp_reloc *r; 235 236 r = malloc(sizeof(struct mips_tmp_reloc), M_TEMP, M_NOWAIT); 237 if (r == NULL) { 238 printf("%s: failed to malloc\n", __func__); 239 return (0); 240 } 241 242 r->ahl = ahl; 243 r->where_hi16 = where_hi16; 244 r->next = ml; 245 ml = r; 246 247 return (1); 248 } 249 250 /* 251 * Flush the temporary relocation list. 252 * 253 * This should be done after a file is completely loaded 254 * so no stale relocations exist to confuse the next 255 * load. 256 */ 257 static void 258 mips_tmp_reloc_flush(void) 259 { 260 struct mips_tmp_reloc *r, *rn; 261 262 r = ml; 263 ml = NULL; 264 while (r != NULL) { 265 rn = r->next; 266 free(r, M_TEMP); 267 r = rn; 268 } 269 } 270 271 /* 272 * Get an entry from the reloc list; or NULL if we've run out. 273 */ 274 static struct mips_tmp_reloc * 275 mips_tmp_reloc_get(void) 276 { 277 struct mips_tmp_reloc *r; 278 279 r = ml; 280 if (r == NULL) 281 return (NULL); 282 ml = ml->next; 283 return (r); 284 } 285 286 /* 287 * Free a relocation entry. 288 */ 289 static void 290 mips_tmp_reloc_free(struct mips_tmp_reloc *r) 291 { 292 293 free(r, M_TEMP); 294 } 295 296 bool 297 elf_is_ifunc_reloc(Elf_Size r_info __unused) 298 { 299 300 return (false); 301 } 302 303 /* Process one elf relocation with addend. */ 304 static int 305 elf_reloc_internal(linker_file_t lf, Elf_Addr relocbase, const void *data, 306 int type, int local, elf_lookup_fn lookup) 307 { 308 Elf32_Addr *where = (Elf32_Addr *)NULL; 309 Elf_Addr addr; 310 Elf_Addr addend = (Elf_Addr)0; 311 Elf_Word rtype = (Elf_Word)0, symidx; 312 struct mips_tmp_reloc *r; 313 const Elf_Rel *rel = NULL; 314 const Elf_Rela *rela = NULL; 315 int error; 316 317 /* Store the last seen ahl from a HI16 for LO16 processing */ 318 static Elf_Addr last_ahl; 319 320 switch (type) { 321 case ELF_RELOC_REL: 322 rel = (const Elf_Rel *)data; 323 where = (Elf32_Addr *) (relocbase + rel->r_offset); 324 rtype = ELF_R_TYPE(rel->r_info); 325 symidx = ELF_R_SYM(rel->r_info); 326 switch (rtype) { 327 case R_MIPS_64: 328 addend = *(Elf64_Addr *)where; 329 break; 330 default: 331 addend = *where; 332 break; 333 } 334 335 break; 336 case ELF_RELOC_RELA: 337 rela = (const Elf_Rela *)data; 338 where = (Elf32_Addr *) (relocbase + rela->r_offset); 339 addend = rela->r_addend; 340 rtype = ELF_R_TYPE(rela->r_info); 341 symidx = ELF_R_SYM(rela->r_info); 342 break; 343 default: 344 panic("unknown reloc type %d\n", type); 345 } 346 347 switch (rtype) { 348 case R_MIPS_NONE: /* none */ 349 break; 350 351 case R_MIPS_32: /* S + A */ 352 error = lookup(lf, symidx, 1, &addr); 353 if (error != 0) 354 return (-1); 355 addr += addend; 356 if (*where != addr) 357 *where = (Elf32_Addr)addr; 358 break; 359 360 case R_MIPS_26: /* ((A << 2) | (P & 0xf0000000) + S) >> 2 */ 361 error = lookup(lf, symidx, 1, &addr); 362 if (error != 0) 363 return (-1); 364 365 addend &= 0x03ffffff; 366 /* 367 * Addendum for .rela R_MIPS_26 is not shifted right 368 */ 369 if (rela == NULL) 370 addend <<= 2; 371 372 addr += ((Elf_Addr)where & 0xf0000000) | addend; 373 addr >>= 2; 374 375 *where &= ~0x03ffffff; 376 *where |= addr & 0x03ffffff; 377 break; 378 379 case R_MIPS_64: /* S + A */ 380 error = lookup(lf, symidx, 1, &addr); 381 if (error != 0) 382 return (-1); 383 addr += addend; 384 if (*(Elf64_Addr*)where != addr) 385 *(Elf64_Addr*)where = addr; 386 break; 387 388 /* 389 * Handle the two GNU extension cases: 390 * 391 * + Multiple HI16s followed by a LO16, and 392 * + A HI16 followed by multiple LO16s. 393 * 394 * The former is tricky - the HI16 relocations need 395 * to be buffered until a LO16 occurs, at which point 396 * each HI16 is replayed against the LO16 relocation entry 397 * (with the relevant overflow information.) 398 * 399 * The latter should be easy to handle - when the 400 * first LO16 is seen, write out and flush the 401 * HI16 buffer. Any subsequent LO16 entries will 402 * find a blank relocation buffer. 403 * 404 */ 405 406 case R_MIPS_HI16: /* ((AHL + S) - ((short)(AHL + S)) >> 16 */ 407 if (rela != NULL) { 408 error = lookup(lf, symidx, 1, &addr); 409 if (error != 0) 410 return (-1); 411 addr += addend; 412 *where &= 0xffff0000; 413 *where |= ((((long long) addr + 0x8000LL) >> 16) & 0xffff); 414 } else { 415 /* 416 * Add a temporary relocation to the list; 417 * will pop it off / free the list when 418 * we've found a suitable HI16. 419 */ 420 if (mips_tmp_reloc_add(addend << 16, where) == 0) 421 return (-1); 422 /* 423 * Track the last seen HI16 AHL for use by 424 * the first LO16 AHL calculation. 425 * 426 * The assumption is any intermediary deleted 427 * LO16's were optimised out, so the last 428 * HI16 before the LO16 is the "true" relocation 429 * entry to use for that LO16 write. 430 */ 431 last_ahl = addend << 16; 432 } 433 break; 434 435 case R_MIPS_LO16: /* AHL + S */ 436 if (rela != NULL) { 437 error = lookup(lf, symidx, 1, &addr); 438 if (error != 0) 439 return (-1); 440 addr += addend; 441 *where &= 0xffff0000; 442 *where |= addr & 0xffff; 443 } else { 444 Elf_Addr tmp_ahl; 445 Elf_Addr tmp_addend; 446 447 tmp_ahl = last_ahl + (int16_t) addend; 448 error = lookup(lf, symidx, 1, &addr); 449 if (error != 0) 450 return (-1); 451 452 tmp_addend = addend & 0xffff0000; 453 454 /* Use the last seen ahl for calculating addend */ 455 tmp_addend |= (uint16_t)(tmp_ahl + addr); 456 *where = tmp_addend; 457 458 /* 459 * This logic implements the "we saw multiple HI16 460 * before a LO16" assignment /and/ "we saw multiple 461 * LO16s". 462 * 463 * Multiple LO16s will be handled as a blank 464 * relocation list. 465 * 466 * Multple HI16's are iterated over here. 467 */ 468 while ((r = mips_tmp_reloc_get()) != NULL) { 469 Elf_Addr rahl; 470 471 /* 472 * We have the ahl from the HI16 entry, so 473 * offset it by the 16 bits of the low ahl. 474 */ 475 rahl = r->ahl; 476 rahl += (int16_t) addend; 477 478 tmp_addend = *(r->where_hi16); 479 tmp_addend &= 0xffff0000; 480 tmp_addend |= ((rahl + addr) - 481 (int16_t)(rahl + addr)) >> 16; 482 *(r->where_hi16) = tmp_addend; 483 mips_tmp_reloc_free(r); 484 } 485 } 486 487 break; 488 489 case R_MIPS_HIGHER: /* %higher(A+S) */ 490 error = lookup(lf, symidx, 1, &addr); 491 if (error != 0) 492 return (-1); 493 addr += addend; 494 *where &= 0xffff0000; 495 *where |= (((long long)addr + 0x80008000LL) >> 32) & 0xffff; 496 break; 497 498 case R_MIPS_HIGHEST: /* %highest(A+S) */ 499 error = lookup(lf, symidx, 1, &addr); 500 if (error != 0) 501 return (-1); 502 addr += addend; 503 *where &= 0xffff0000; 504 *where |= (((long long)addr + 0x800080008000LL) >> 48) & 0xffff; 505 break; 506 507 default: 508 printf("kldload: unexpected relocation type %d\n", 509 rtype); 510 return (-1); 511 } 512 513 return(0); 514 } 515 516 int 517 elf_reloc(linker_file_t lf, Elf_Addr relocbase, const void *data, int type, 518 elf_lookup_fn lookup) 519 { 520 521 return (elf_reloc_internal(lf, relocbase, data, type, 0, lookup)); 522 } 523 524 int 525 elf_reloc_local(linker_file_t lf, Elf_Addr relocbase, const void *data, 526 int type, elf_lookup_fn lookup) 527 { 528 529 return (elf_reloc_internal(lf, relocbase, data, type, 1, lookup)); 530 } 531 532 int 533 elf_cpu_load_file(linker_file_t lf __unused) 534 { 535 536 /* 537 * Sync the I and D caches to make sure our relocations are visible. 538 */ 539 mips_icache_sync_all(); 540 541 /* Flush outstanding relocations */ 542 mips_tmp_reloc_flush(); 543 544 return (0); 545 } 546 547 int 548 elf_cpu_unload_file(linker_file_t lf __unused) 549 { 550 551 return (0); 552 }
Cache object: f3b783371ce1ff1ec727ff1742074884
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