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 static struct sysentvec elf_freebsd_sysvec = { 55 .sv_size = SYS_MAXSYSCALL, 56 .sv_table = sysent, 57 .sv_transtrap = NULL, 58 .sv_fixup = __elfN(freebsd_fixup), 59 .sv_sendsig = sendsig, 60 .sv_sigcode = sigcode, 61 .sv_szsigcode = &szsigcode, 62 #ifdef __mips_n64 63 .sv_name = "FreeBSD ELF64", 64 #else 65 .sv_name = "FreeBSD ELF32", 66 #endif 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_auxargs = __elfN(freebsd_copyout_auxargs), 76 .sv_copyout_strings = exec_copyout_strings, 77 .sv_setregs = exec_setregs, 78 .sv_fixlimit = NULL, 79 .sv_maxssiz = NULL, 80 .sv_flags = SV_ABI_FREEBSD | SV_ASLR | SV_RNG_SEED_VER | 81 #ifdef __mips_n64 82 SV_LP64, 83 #else 84 SV_ILP32, 85 #endif 86 .sv_set_syscall_retval = cpu_set_syscall_retval, 87 .sv_fetch_syscall_args = cpu_fetch_syscall_args, 88 .sv_syscallnames = syscallnames, 89 .sv_schedtail = NULL, 90 .sv_thread_detach = NULL, 91 .sv_trap = NULL, 92 }; 93 94 static __ElfN(Brandinfo) freebsd_brand_info = { 95 .brand = ELFOSABI_FREEBSD, 96 .machine = EM_MIPS, 97 .compat_3_brand = "FreeBSD", 98 .emul_path = NULL, 99 .interp_path = "/libexec/ld-elf.so.1", 100 .sysvec = &elf_freebsd_sysvec, 101 .interp_newpath = NULL, 102 .brand_note = &__elfN(freebsd_brandnote), 103 .flags = BI_CAN_EXEC_DYN | BI_BRAND_NOTE 104 }; 105 106 SYSINIT(elf, SI_SUB_EXEC, SI_ORDER_ANY, 107 (sysinit_cfunc_t) __elfN(insert_brand_entry), 108 &freebsd_brand_info); 109 110 void 111 __elfN(dump_thread)(struct thread *td __unused, void *dst __unused, 112 size_t *off __unused) 113 { 114 } 115 116 /* 117 * The following MIPS relocation code for tracking multiple 118 * consecutive HI32/LO32 entries is because of the following: 119 * 120 * https://dmz-portal.mips.com/wiki/MIPS_relocation_types 121 * 122 * === 123 * 124 * + R_MIPS_HI16 125 * 126 * An R_MIPS_HI16 must be followed eventually by an associated R_MIPS_LO16 127 * relocation record in the same SHT_REL section. The contents of the two 128 * fields to be relocated are combined to form a full 32-bit addend AHL. 129 * An R_MIPS_LO16 entry which does not immediately follow a R_MIPS_HI16 is 130 * combined with the most recent one encountered, i.e. multiple R_MIPS_LO16 131 * entries may be associated with a single R_MIPS_HI16. Use of these 132 * relocation types in a SHT_REL section is discouraged and may be 133 * forbidden to avoid this complication. 134 * 135 * A GNU extension allows multiple R_MIPS_HI16 records to share the same 136 * R_MIPS_LO16 relocation record(s). The association works like this within 137 * a single relocation section: 138 * 139 * + From the beginning of the section moving to the end of the section, 140 * until R_MIPS_LO16 is not found each found R_MIPS_HI16 relocation will 141 * be associated with the first R_MIPS_LO16. 142 * 143 * + Until another R_MIPS_HI16 record is found all found R_MIPS_LO16 144 * relocations found are associated with the last R_MIPS_HI16. 145 * 146 * === 147 * 148 * This is so gcc can do dead code detection/removal without having to 149 * generate HI/LO pairs even if one of them would be deleted. 150 * 151 * So, the summary is: 152 * 153 * + A HI16 entry must occur before any LO16 entries; 154 * + Multiple consecutive HI16 RELA entries need to be buffered until the 155 * first LO16 RELA entry occurs - and then all HI16 RELA relocations use 156 * the offset in the LOW16 RELA for calculating their offsets; 157 * + The last HI16 RELA entry before a LO16 RELA entry is used (the AHL) 158 * for the first subsequent LO16 calculation; 159 * + If multiple consecutive LO16 RELA entries occur, only the first 160 * LO16 RELA entry triggers an update of buffered HI16 RELA entries; 161 * any subsequent LO16 RELA entry before another HI16 RELA entry will 162 * not cause any further updates to the HI16 RELA entries. 163 * 164 * Additionally, flush out any outstanding HI16 entries that don't have 165 * a LO16 entry in case some garbage entries are left in the file. 166 */ 167 168 struct mips_tmp_reloc; 169 struct mips_tmp_reloc { 170 struct mips_tmp_reloc *next; 171 172 Elf_Addr ahl; 173 Elf32_Addr *where_hi16; 174 }; 175 176 static struct mips_tmp_reloc *ml = NULL; 177 178 /* 179 * Add a temporary relocation (ie, a HI16 reloc type.) 180 */ 181 static int 182 mips_tmp_reloc_add(Elf_Addr ahl, Elf32_Addr *where_hi16) 183 { 184 struct mips_tmp_reloc *r; 185 186 r = malloc(sizeof(struct mips_tmp_reloc), M_TEMP, M_NOWAIT); 187 if (r == NULL) { 188 printf("%s: failed to malloc\n", __func__); 189 return (0); 190 } 191 192 r->ahl = ahl; 193 r->where_hi16 = where_hi16; 194 r->next = ml; 195 ml = r; 196 197 return (1); 198 } 199 200 /* 201 * Flush the temporary relocation list. 202 * 203 * This should be done after a file is completely loaded 204 * so no stale relocations exist to confuse the next 205 * load. 206 */ 207 static void 208 mips_tmp_reloc_flush(void) 209 { 210 struct mips_tmp_reloc *r, *rn; 211 212 r = ml; 213 ml = NULL; 214 while (r != NULL) { 215 rn = r->next; 216 free(r, M_TEMP); 217 r = rn; 218 } 219 } 220 221 /* 222 * Get an entry from the reloc list; or NULL if we've run out. 223 */ 224 static struct mips_tmp_reloc * 225 mips_tmp_reloc_get(void) 226 { 227 struct mips_tmp_reloc *r; 228 229 r = ml; 230 if (r == NULL) 231 return (NULL); 232 ml = ml->next; 233 return (r); 234 } 235 236 /* 237 * Free a relocation entry. 238 */ 239 static void 240 mips_tmp_reloc_free(struct mips_tmp_reloc *r) 241 { 242 243 free(r, M_TEMP); 244 } 245 246 bool 247 elf_is_ifunc_reloc(Elf_Size r_info __unused) 248 { 249 250 return (false); 251 } 252 253 /* Process one elf relocation with addend. */ 254 static int 255 elf_reloc_internal(linker_file_t lf, Elf_Addr relocbase, const void *data, 256 int type, int local, elf_lookup_fn lookup) 257 { 258 Elf32_Addr *where = (Elf32_Addr *)NULL; 259 Elf_Addr addr; 260 Elf_Addr addend = (Elf_Addr)0; 261 Elf_Word rtype = (Elf_Word)0, symidx; 262 struct mips_tmp_reloc *r; 263 const Elf_Rel *rel = NULL; 264 const Elf_Rela *rela = NULL; 265 int error; 266 267 /* Store the last seen ahl from a HI16 for LO16 processing */ 268 static Elf_Addr last_ahl; 269 270 switch (type) { 271 case ELF_RELOC_REL: 272 rel = (const Elf_Rel *)data; 273 where = (Elf32_Addr *) (relocbase + rel->r_offset); 274 rtype = ELF_R_TYPE(rel->r_info); 275 symidx = ELF_R_SYM(rel->r_info); 276 switch (rtype) { 277 case R_MIPS_64: 278 addend = *(Elf64_Addr *)where; 279 break; 280 default: 281 addend = *where; 282 break; 283 } 284 285 break; 286 case ELF_RELOC_RELA: 287 rela = (const Elf_Rela *)data; 288 where = (Elf32_Addr *) (relocbase + rela->r_offset); 289 addend = rela->r_addend; 290 rtype = ELF_R_TYPE(rela->r_info); 291 symidx = ELF_R_SYM(rela->r_info); 292 break; 293 default: 294 panic("unknown reloc type %d\n", type); 295 } 296 297 switch (rtype) { 298 case R_MIPS_NONE: /* none */ 299 break; 300 301 case R_MIPS_32: /* S + A */ 302 error = lookup(lf, symidx, 1, &addr); 303 if (error != 0) 304 return (-1); 305 addr += addend; 306 if (*where != addr) 307 *where = (Elf32_Addr)addr; 308 break; 309 310 case R_MIPS_26: /* ((A << 2) | (P & 0xf0000000) + S) >> 2 */ 311 error = lookup(lf, symidx, 1, &addr); 312 if (error != 0) 313 return (-1); 314 315 addend &= 0x03ffffff; 316 /* 317 * Addendum for .rela R_MIPS_26 is not shifted right 318 */ 319 if (rela == NULL) 320 addend <<= 2; 321 322 addr += ((Elf_Addr)where & 0xf0000000) | addend; 323 addr >>= 2; 324 325 *where &= ~0x03ffffff; 326 *where |= addr & 0x03ffffff; 327 break; 328 329 case R_MIPS_64: /* S + A */ 330 error = lookup(lf, symidx, 1, &addr); 331 if (error != 0) 332 return (-1); 333 addr += addend; 334 if (*(Elf64_Addr*)where != addr) 335 *(Elf64_Addr*)where = addr; 336 break; 337 338 /* 339 * Handle the two GNU extension cases: 340 * 341 * + Multiple HI16s followed by a LO16, and 342 * + A HI16 followed by multiple LO16s. 343 * 344 * The former is tricky - the HI16 relocations need 345 * to be buffered until a LO16 occurs, at which point 346 * each HI16 is replayed against the LO16 relocation entry 347 * (with the relevant overflow information.) 348 * 349 * The latter should be easy to handle - when the 350 * first LO16 is seen, write out and flush the 351 * HI16 buffer. Any subsequent LO16 entries will 352 * find a blank relocation buffer. 353 * 354 */ 355 356 case R_MIPS_HI16: /* ((AHL + S) - ((short)(AHL + S)) >> 16 */ 357 if (rela != NULL) { 358 error = lookup(lf, symidx, 1, &addr); 359 if (error != 0) 360 return (-1); 361 addr += addend; 362 *where &= 0xffff0000; 363 *where |= ((((long long) addr + 0x8000LL) >> 16) & 0xffff); 364 } else { 365 /* 366 * Add a temporary relocation to the list; 367 * will pop it off / free the list when 368 * we've found a suitable HI16. 369 */ 370 if (mips_tmp_reloc_add(addend << 16, where) == 0) 371 return (-1); 372 /* 373 * Track the last seen HI16 AHL for use by 374 * the first LO16 AHL calculation. 375 * 376 * The assumption is any intermediary deleted 377 * LO16's were optimised out, so the last 378 * HI16 before the LO16 is the "true" relocation 379 * entry to use for that LO16 write. 380 */ 381 last_ahl = addend << 16; 382 } 383 break; 384 385 case R_MIPS_LO16: /* AHL + S */ 386 if (rela != NULL) { 387 error = lookup(lf, symidx, 1, &addr); 388 if (error != 0) 389 return (-1); 390 addr += addend; 391 *where &= 0xffff0000; 392 *where |= addr & 0xffff; 393 } else { 394 Elf_Addr tmp_ahl; 395 Elf_Addr tmp_addend; 396 397 tmp_ahl = last_ahl + (int16_t) addend; 398 error = lookup(lf, symidx, 1, &addr); 399 if (error != 0) 400 return (-1); 401 402 tmp_addend = addend & 0xffff0000; 403 404 /* Use the last seen ahl for calculating addend */ 405 tmp_addend |= (uint16_t)(tmp_ahl + addr); 406 *where = tmp_addend; 407 408 /* 409 * This logic implements the "we saw multiple HI16 410 * before a LO16" assignment /and/ "we saw multiple 411 * LO16s". 412 * 413 * Multiple LO16s will be handled as a blank 414 * relocation list. 415 * 416 * Multple HI16's are iterated over here. 417 */ 418 while ((r = mips_tmp_reloc_get()) != NULL) { 419 Elf_Addr rahl; 420 421 /* 422 * We have the ahl from the HI16 entry, so 423 * offset it by the 16 bits of the low ahl. 424 */ 425 rahl = r->ahl; 426 rahl += (int16_t) addend; 427 428 tmp_addend = *(r->where_hi16); 429 tmp_addend &= 0xffff0000; 430 tmp_addend |= ((rahl + addr) - 431 (int16_t)(rahl + addr)) >> 16; 432 *(r->where_hi16) = tmp_addend; 433 mips_tmp_reloc_free(r); 434 } 435 } 436 437 break; 438 439 case R_MIPS_HIGHER: /* %higher(A+S) */ 440 error = lookup(lf, symidx, 1, &addr); 441 if (error != 0) 442 return (-1); 443 addr += addend; 444 *where &= 0xffff0000; 445 *where |= (((long long)addr + 0x80008000LL) >> 32) & 0xffff; 446 break; 447 448 case R_MIPS_HIGHEST: /* %highest(A+S) */ 449 error = lookup(lf, symidx, 1, &addr); 450 if (error != 0) 451 return (-1); 452 addr += addend; 453 *where &= 0xffff0000; 454 *where |= (((long long)addr + 0x800080008000LL) >> 48) & 0xffff; 455 break; 456 457 default: 458 printf("kldload: unexpected relocation type %d, " 459 "symbol index %d\n", rtype, symidx); 460 return (-1); 461 } 462 463 return (0); 464 } 465 466 int 467 elf_reloc(linker_file_t lf, Elf_Addr relocbase, const void *data, int type, 468 elf_lookup_fn lookup) 469 { 470 471 return (elf_reloc_internal(lf, relocbase, data, type, 0, lookup)); 472 } 473 474 int 475 elf_reloc_local(linker_file_t lf, Elf_Addr relocbase, const void *data, 476 int type, elf_lookup_fn lookup) 477 { 478 479 return (elf_reloc_internal(lf, relocbase, data, type, 1, lookup)); 480 } 481 482 int 483 elf_cpu_load_file(linker_file_t lf __unused) 484 { 485 486 /* 487 * Sync the I and D caches to make sure our relocations are visible. 488 */ 489 mips_icache_sync_all(); 490 491 /* Flush outstanding relocations */ 492 mips_tmp_reloc_flush(); 493 494 return (0); 495 } 496 497 int 498 elf_cpu_unload_file(linker_file_t lf __unused) 499 { 500 501 return (0); 502 } 503 504 int 505 elf_cpu_parse_dynamic(caddr_t loadbase __unused, Elf_Dyn *dynamic __unused) 506 { 507 508 return (0); 509 }
Cache object: 41a069ba8b7fa8d805bd59727000ce37
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