sys/kern/link_aout.c

   1 /*-
   2  * Copyright (c) 1997 Doug Rabson
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD: src/sys/kern/link_aout.c,v 1.26 1999/12/24 15:33:36 bde Exp $
  27  * $DragonFly: src/sys/kern/link_aout.c,v 1.24 2008/02/06 22:37:46 nth Exp $
  28  */
  29
  30 #define FREEBSD_AOUT    1
  31
  32 #include <sys/param.h>
  33 #include <sys/kernel.h>
  34 #include <sys/systm.h>
  35 #include <sys/types.h>
  36 #include <sys/malloc.h>
  37 #include <sys/proc.h>
  38 #include <sys/nlookup.h>
  39 #include <sys/fcntl.h>
  40 #include <sys/vnode.h>
  41 #include <sys/linker.h>
  42
  43 #include <vm/vm_zone.h>
  44
  45 #ifndef __ELF__
  46 #include <vm/vm.h>
  47 #include <vm/pmap.h>
  48 #include <machine/vmparam.h>
  49 #endif
  50
  51 #include <machine/exec.h>
  52 #include <sys/imgact_aout.h>
  53 #include <machine/reloc.h>
  54 #define _AOUT_INCLUDE_
  55 #include <sys/nlist_aout.h>
  56 #include <sys/link_aout.h>
  57
  58 static int              link_aout_load_module(const char*, linker_file_t*,int);
  59
  60 static int              link_aout_load_file(const char*, linker_file_t*,int);
  61
  62 static int              link_aout_lookup_symbol(linker_file_t, const char*,
  63                                                 c_linker_sym_t*);
  64 static int              link_aout_symbol_values(linker_file_t file, c_linker_sym_t sym,
  65                                                 linker_symval_t* symval);
  66 static int              link_aout_search_symbol(linker_file_t lf, caddr_t value,
  67                                                 c_linker_sym_t* sym, long* diffp);
  68 static void             link_aout_unload_file(linker_file_t);
  69 static void             link_aout_unload_module(linker_file_t);
  70 static int              link_aout_lookup_set(linker_file_t lf, const char *name,
  71                                 void ***startp, void ***stopp, int *countp);
  72
  73 static struct linker_class_ops link_aout_class_ops = {
  74     link_aout_load_module,
  75 };
  76
  77 static struct linker_file_ops link_aout_file_ops = {
  78     link_aout_lookup_symbol,
  79     link_aout_symbol_values,
  80     link_aout_search_symbol,
  81     link_aout_unload_file,
  82     link_aout_lookup_set
  83 };
  84 static struct linker_file_ops link_aout_module_ops = {
  85     link_aout_lookup_symbol,
  86     link_aout_symbol_values,
  87     link_aout_search_symbol,
  88     link_aout_unload_module,
  89     link_aout_lookup_set
  90 };
  91
  92 typedef struct aout_file {
  93     char*               address;        /* Load address */
  94     struct _dynamic*    dynamic;        /* Symbol table etc. */
  95 } *aout_file_t;
  96
  97 static int              load_dependancies(linker_file_t lf, int load_flags);
  98 static int              relocate_file(linker_file_t lf);
  99
 100 /*
 101  * The kernel symbol table starts here.
 102  */
 103 extern struct _dynamic _DYNAMIC;
 104
 105 static void
 106 link_aout_init(void* arg)
 107 {
 108 #ifndef __ELF__
 109     struct _dynamic* dp = &_DYNAMIC;
 110 #endif
 111
 112     linker_add_class("a.out", NULL, &link_aout_class_ops);
 113
 114 #ifndef __ELF__
 115     if (dp) {
 116         aout_file_t af;
 117
 118         af = kmalloc(sizeof(struct aout_file), M_LINKER, M_NOWAIT | M_ZERO);
 119         if (af == NULL)
 120             panic("link_aout_init: Can't create linker structures for kernel");
 121
 122         af->address = 0;
 123         af->dynamic = dp;
 124         linker_kernel_file =
 125             linker_make_file(kernelname, af, &link_aout_file_ops);
 126         if (linker_kernel_file == NULL)
 127             panic("link_aout_init: Can't create linker structures for kernel");
 128         linker_kernel_file->address = (caddr_t) KERNBASE;
 129         linker_kernel_file->size = -(long)linker_kernel_file->address;
 130         linker_current_file = linker_kernel_file;
 131         linker_kernel_file->flags |= LINKER_FILE_LINKED;
 132     }
 133 #endif
 134 }
 135
 136 SYSINIT(link_aout, SI_BOOT2_KLD, SI_ORDER_THIRD, link_aout_init, 0);
 137
 138 static int
 139 link_aout_load_module(const char *filename, linker_file_t *result,
 140                       int load_flags)
 141 {
 142     caddr_t             modptr, baseptr;
 143     char                *type;
 144     struct exec         *ehdr;
 145     aout_file_t         af;
 146     linker_file_t       lf;
 147     int                 error;
 148
 149     /* Look to see if we have the module preloaded. */
 150     if ((modptr = preload_search_by_name(filename)) == NULL)
 151         return(link_aout_load_file(filename, result, load_flags));
 152
 153     /* It's preloaded, check we can handle it and collect information. */
 154     if (((type = (char *)preload_search_info(modptr, MODINFO_TYPE)) == NULL) ||
 155         strcmp(type, "a.out module") ||
 156         ((baseptr = preload_search_info(modptr, MODINFO_ADDR)) == NULL) ||
 157         ((ehdr = (struct exec *)preload_search_info(modptr, MODINFO_METADATA | MODINFOMD_AOUTEXEC)) == NULL))
 158         return(0);                      /* we can't handle this */
 159
 160     /* Looks like we can handle this one */
 161     af = kmalloc(sizeof(struct aout_file), M_LINKER, M_WAITOK | M_ZERO);
 162     af->address = baseptr;
 163
 164     /* Assume _DYNAMIC is the first data item. */
 165     af->dynamic = (struct _dynamic*)(af->address + ehdr->a_text);
 166     if (af->dynamic->d_version != LD_VERSION_BSD) {
 167         kfree(af, M_LINKER);
 168         return(0);                      /* we can't handle this */
 169     }
 170     af->dynamic->d_un.d_sdt = (struct section_dispatch_table *)
 171         ((char *)af->dynamic->d_un.d_sdt + (vm_offset_t)af->address);
 172
 173     /* Register with kld */
 174     lf = linker_make_file(filename, af, &link_aout_module_ops);
 175     if (lf == NULL) {
 176         kfree(af, M_LINKER);
 177         return(ENOMEM);
 178     }
 179     lf->address = af->address;
 180     lf->size = ehdr->a_text + ehdr->a_data + ehdr->a_bss;
 181
 182     /* Try to load dependancies */
 183     if (((error = load_dependancies(lf, load_flags)) != 0) ||
 184         ((error = relocate_file(lf)) != 0)) {
 185         linker_file_unload(lf);
 186         return(error);
 187     }
 188     lf->flags |= LINKER_FILE_LINKED;
 189     *result = lf;
 190     return(0);
 191 }
 192
 193 static int
 194 link_aout_load_file(const char *filename, linker_file_t *result, int load_flags)
 195 {
 196     struct nlookupdata nd;
 197     struct thread *td = curthread;
 198     struct proc *p = td->td_proc;
 199     struct vnode *vp;
 200     int error = 0;
 201     int resid;
 202     struct exec header;
 203     aout_file_t af;
 204     linker_file_t lf;
 205     char *pathname;
 206
 207     KKASSERT(p != NULL);
 208
 209     if (p->p_ucred == NULL) {
 210         kprintf("link_aout_load_file: cannot load '%s' from filesystem"
 211                 " this early\n", filename);
 212         return ENOENT;
 213     }
 214
 215     pathname = linker_search_path(filename);
 216     if (pathname == NULL)
 217         return ENOENT;
 218     error = nlookup_init(&nd, pathname, UIO_SYSSPACE, NLC_FOLLOW|NLC_LOCKVP);
 219     if (error == 0)
 220         error = vn_open(&nd, NULL, FREAD, 0);
 221     kfree(pathname, M_LINKER);
 222     if (error) {
 223         nlookup_done(&nd);
 224         return error;
 225     }
 226     vp = nd.nl_open_vp;
 227     nd.nl_open_vp = NULL;
 228     nlookup_done(&nd);
 229
 230     /*
 231      * Read the a.out header from the file.
 232      */
 233     error = vn_rdwr(UIO_READ, vp, (void*) &header, sizeof header, 0,
 234                     UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid);
 235     if (error)
 236         goto out;
 237
 238     if (N_BADMAG(header) || !(N_GETFLAG(header) & EX_DYNAMIC))
 239         goto out;
 240
 241     /*
 242      * We have an a.out file, so make some space to read it in.
 243      */
 244     af = kmalloc(sizeof(struct aout_file), M_LINKER, M_WAITOK | M_ZERO);
 245     af->address = kmalloc(header.a_text + header.a_data + header.a_bss,
 246                          M_LINKER, M_WAITOK);
 247
 248     /*
 249      * Read the text and data sections and zero the bss.
 250      */
 251     error = vn_rdwr(UIO_READ, vp, (void*) af->address,
 252                     header.a_text + header.a_data, 0,
 253                     UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid);
 254     if (error)
 255         goto out;
 256     bzero(af->address + header.a_text + header.a_data, header.a_bss);
 257
 258     /*
 259      * Assume _DYNAMIC is the first data item.
 260      */
 261     af->dynamic = (struct _dynamic*) (af->address + header.a_text);
 262     if (af->dynamic->d_version != LD_VERSION_BSD) {
 263         kfree(af->address, M_LINKER);
 264         kfree(af, M_LINKER);
 265         goto out;
 266     }
 267     af->dynamic->d_un.d_sdt = (struct section_dispatch_table *)
 268         ((char *)af->dynamic->d_un.d_sdt + (vm_offset_t)af->address);
 269
 270     lf = linker_make_file(filename, af, &link_aout_file_ops);
 271     if (lf == NULL) {
 272         kfree(af->address, M_LINKER);
 273         kfree(af, M_LINKER);
 274         error = ENOMEM;
 275         goto out;
 276     }
 277     lf->address = af->address;
 278     lf->size = header.a_text + header.a_data + header.a_bss;
 279
 280     if ((error = load_dependancies(lf, load_flags)) != 0
 281         || (error = relocate_file(lf)) != 0) {
 282         linker_file_unload(lf);
 283         goto out;
 284     }
 285
 286     lf->flags |= LINKER_FILE_LINKED;
 287     *result = lf;
 288
 289 out:
 290     vn_unlock(vp);
 291     vn_close(vp, FREAD);
 292
 293     return error;
 294 }
 295
 296 static void
 297 link_aout_unload_file(linker_file_t file)
 298 {
 299     aout_file_t af = file->priv;
 300
 301     if (af) {
 302         if (af->address)
 303             kfree(af->address, M_LINKER);
 304         kfree(af, M_LINKER);
 305     }
 306 }
 307
 308 static void
 309 link_aout_unload_module(linker_file_t file)
 310 {
 311     aout_file_t af = file->priv;
 312
 313     if (af)
 314         kfree(af, M_LINKER);
 315     if (file->filename)
 316         preload_delete_name(file->filename);
 317 }
 318
 319 #define AOUT_RELOC(af, type, off) (type*) ((af)->address + (off))
 320
 321 static int
 322 load_dependancies(linker_file_t lf, int load_flags)
 323 {
 324     aout_file_t af = lf->priv;
 325     linker_file_t lfdep;
 326     long off;
 327     struct sod* sodp;
 328     char* name;
 329     char* filename = 0;
 330     int error = 0;
 331
 332     /*
 333      * All files are dependant on /kernel.
 334      */
 335     if (linker_kernel_file) {
 336         linker_kernel_file->refs++;
 337         linker_file_add_dependancy(lf, linker_kernel_file);
 338     }
 339
 340     off = LD_NEED(af->dynamic);
 341
 342     /*
 343      * Load the dependancies.
 344      */
 345     while (off != 0) {
 346         sodp = AOUT_RELOC(af, struct sod, off);
 347         name = AOUT_RELOC(af, char, sodp->sod_name);
 348
 349         error = linker_load_file(name, &lfdep, load_flags);
 350         if (error)
 351             goto out;
 352         linker_file_add_dependancy(lf, lfdep);
 353         off = sodp->sod_next;
 354     }
 355
 356 out:
 357     if (filename)
 358         kfree(filename, M_TEMP);
 359     return error;
 360 }
 361
 362 /*
 363  * XXX i386 dependant.
 364  */
 365 static long
 366 read_relocation(struct relocation_info* r, char* addr)
 367 {
 368     int length = r->r_length;
 369     if (length == 0)
 370         return *(u_char*) addr;
 371     else if (length == 1)
 372         return *(u_short*) addr;
 373     else if (length == 2)
 374         return *(u_int*) addr;
 375     else
 376         kprintf("link_aout: unsupported relocation size %d\n", r->r_length);
 377     return 0;
 378 }
 379
 380 static void
 381 write_relocation(struct relocation_info* r, char* addr, long value)
 382 {
 383     int length = r->r_length;
 384     if (length == 0)
 385         *(u_char*) addr = value;
 386     else if (length == 1)
 387         *(u_short*) addr = value;
 388     else if (length == 2)
 389         *(u_int*) addr = value;
 390     else
 391         kprintf("link_aout: unsupported relocation size %d\n", r->r_length);
 392 }
 393
 394 static int
 395 relocate_file(linker_file_t lf)
 396 {
 397     aout_file_t af = lf->priv;
 398     struct relocation_info* rel;
 399     struct relocation_info* erel;
 400     struct relocation_info* r;
 401     struct nzlist* symbolbase;
 402     char* stringbase;
 403     struct nzlist* np;
 404     char* sym;
 405     long relocation;
 406
 407     rel = AOUT_RELOC(af, struct relocation_info, LD_REL(af->dynamic));
 408     erel = AOUT_RELOC(af, struct relocation_info,
 409                       LD_REL(af->dynamic) + LD_RELSZ(af->dynamic));
 410     symbolbase = AOUT_RELOC(af, struct nzlist, LD_SYMBOL(af->dynamic));
 411     stringbase = AOUT_RELOC(af, char, LD_STRINGS(af->dynamic));
 412
 413     for (r = rel; r < erel; r++) {
 414         char* addr;
 415
 416         if (r->r_address == 0)
 417             break;
 418
 419         addr = AOUT_RELOC(af, char, r->r_address);
 420         if (r->r_extern) {
 421             np = &symbolbase[r->r_symbolnum];
 422             sym = &stringbase[np->nz_strx];
 423
 424             if (sym[0] != '_') {
 425                 kprintf("link_aout: bad symbol name %s\n", sym);
 426                 kprintf("link_aout: symbol %s not found\n", sym);
 427                 return ENOENT;
 428             } else {
 429                 if (linker_file_lookup_symbol(lf, sym + 1,
 430                     (np->nz_type != (N_SETV+N_EXT)), (caddr_t *)&relocation)) {
 431                         kprintf("link_aout: symbol %s not found\n", sym);
 432                         return ENOENT;
 433                 }
 434             }
 435
 436             relocation += read_relocation(r, addr);
 437
 438             if (r->r_jmptable) {
 439                 kprintf("link_aout: can't cope with jump table relocations\n");
 440                 continue;
 441             }
 442
 443             if (r->r_pcrel)
 444                 relocation -= (intptr_t) af->address;
 445
 446             if (r->r_copy) {
 447                 kprintf("link_aout: can't cope with copy relocations\n");
 448                 continue;
 449             }
 450
 451             write_relocation(r, addr, relocation);
 452         } else {
 453             write_relocation(r, addr,
 454                              (intptr_t)(read_relocation(r, addr) + af->address));
 455         }
 456
 457     }
 458
 459     return 0;
 460 }
 461
 462 static long
 463 symbol_hash_value(aout_file_t af, const char* name)
 464 {
 465     long hashval;
 466     const char* p;
 467
 468     hashval = '_';              /* fake a starting '_' for C symbols */
 469     for (p = name; *p; p++)
 470         hashval = (hashval << 1) + *p;
 471
 472     return (hashval & 0x7fffffff) % LD_BUCKETS(af->dynamic);
 473 }
 474
 475 int
 476 link_aout_lookup_symbol(linker_file_t file, const char* name,
 477                         c_linker_sym_t* sym)
 478 {
 479     aout_file_t af = file->priv;
 480     long hashval;
 481     struct rrs_hash* hashbase;
 482     struct nzlist* symbolbase;
 483     char* stringbase;
 484     struct rrs_hash* hp;
 485     struct nzlist* np;
 486     char* cp;
 487
 488     if (LD_BUCKETS(af->dynamic) == 0)
 489         return 0;
 490
 491     hashbase = AOUT_RELOC(af, struct rrs_hash, LD_HASH(af->dynamic));
 492     symbolbase = AOUT_RELOC(af, struct nzlist, LD_SYMBOL(af->dynamic));
 493     stringbase = AOUT_RELOC(af, char, LD_STRINGS(af->dynamic));
 494
 495 restart:
 496     hashval = symbol_hash_value(af, name);
 497     hp = &hashbase[hashval];
 498     if (hp->rh_symbolnum == -1)
 499         return ENOENT;
 500
 501     while (hp) {
 502         np = (struct nzlist *) &symbolbase[hp->rh_symbolnum];
 503         cp = stringbase + np->nz_strx;
 504         /*
 505          * Note: we fake the leading '_' for C symbols.
 506          */
 507         if (cp[0] == '_' && !strcmp(cp + 1, name))
 508             break;
 509
 510         if (hp->rh_next == 0)
 511             hp = NULL;
 512         else
 513             hp = &hashbase[hp->rh_next];
 514     }
 515
 516     if (hp == NULL)
 517         /*
 518          * Not found.
 519          */
 520         return ENOENT;
 521
 522     /*
 523      * Check for an aliased symbol, whatever that is.
 524      */
 525     if (np->nz_type == N_INDR+N_EXT) {
 526         name = stringbase + (++np)->nz_strx + 1; /* +1 for '_' */
 527         goto restart;
 528     }
 529
 530     /*
 531      * Check this is an actual definition of the symbol.
 532      */
 533     if (np->nz_value == 0)
 534         return ENOENT;
 535
 536     if (np->nz_type == N_UNDF+N_EXT && np->nz_value != 0) {
 537         if (np->nz_other == AUX_FUNC)
 538             /* weak function */
 539             return ENOENT;
 540     }
 541
 542     *sym = (linker_sym_t) np;
 543
 544     return 0;
 545 }
 546
 547
 548 static int
 549 link_aout_symbol_values(linker_file_t file, c_linker_sym_t sym,
 550                         linker_symval_t* symval)
 551 {
 552     aout_file_t af = file->priv;
 553     const struct nzlist* np = (const struct nzlist*) sym;
 554     char* stringbase;
 555     long numsym = LD_STABSZ(af->dynamic) / sizeof(struct nzlist);
 556     struct nzlist *symbase;
 557
 558     /* Is it one of ours?  It could be another module... */
 559     symbase = AOUT_RELOC(af, struct nzlist, LD_SYMBOL(af->dynamic));
 560     if (np < symbase)
 561         return ENOENT;
 562     if ((np - symbase) > numsym)
 563         return ENOENT;
 564
 565     stringbase = AOUT_RELOC(af, char, LD_STRINGS(af->dynamic));
 566
 567     symval->name = stringbase + np->nz_strx + 1; /* +1 for '_' */
 568     if (np->nz_type == N_UNDF+N_EXT && np->nz_value != 0) {
 569         symval->value = 0;
 570         symval->size = np->nz_value;
 571     } else {
 572         symval->value = AOUT_RELOC(af, char, np->nz_value);
 573         symval->size = np->nz_size;
 574     }
 575     return 0;
 576 }
 577
 578 static int
 579 link_aout_search_symbol(linker_file_t lf, caddr_t value,
 580                         c_linker_sym_t* sym, long* diffp)
 581 {
 582         aout_file_t af = lf->priv;
 583         u_long off = (uintptr_t) (void *) value;
 584         u_long diff = off;
 585         u_long sp_nz_value;
 586         struct nzlist* sp;
 587         struct nzlist* ep;
 588         struct nzlist* best = 0;
 589
 590         for (sp = AOUT_RELOC(af, struct nzlist, LD_SYMBOL(af->dynamic)),
 591                  ep = (struct nzlist *) ((caddr_t) sp + LD_STABSZ(af->dynamic));
 592              sp < ep; sp++) {
 593                 if (sp->nz_name == 0)
 594                         continue;
 595                 sp_nz_value = sp->nz_value + (uintptr_t) (void *) af->address;
 596                 if (off >= sp_nz_value) {
 597                         if (off - sp_nz_value < diff) {
 598                                 diff = off - sp_nz_value;
 599                                 best = sp;
 600                                 if (diff == 0)
 601                                         break;
 602                         } else if (off - sp_nz_value == diff) {
 603                                 best = sp;
 604                         }
 605                 }
 606         }
 607         if (best == 0)
 608                 *diffp = off;
 609         else
 610                 *diffp = diff;
 611         *sym = (linker_sym_t) best;
 612
 613         return 0;
 614 }
 615
 616 /*
 617  * Look up a linker set on an a.out + gnu LD system.
 618  */
 619
 620 struct generic_linker_set {
 621         int     ls_length;
 622         void    *ls_items[1];
 623 };
 624
 625 static int
 626 link_aout_lookup_set(linker_file_t lf, const char *name,
 627                     void ***startp, void ***stopp, int *countp)
 628 {
 629         c_linker_sym_t sym;
 630         linker_symval_t symval;
 631         void **start, **stop;
 632         int error, count;
 633         struct generic_linker_set *setp;
 634
 635         error = link_aout_lookup_symbol(lf, name, &sym);
 636         if (error)
 637                return error;
 638         link_aout_symbol_values(lf, sym, &symval);
 639         if (symval.value == 0)
 640                return ESRCH;
 641         setp = (struct generic_linker_set *)symval.value;
 642         count = setp->ls_length;
 643         start = &setp->ls_items[0];
 644         stop = &setp->ls_items[count];
 645         if (startp)
 646                *startp = start;
 647         if (stopp)
 648                *stopp = stop;
 649         if (countp)
 650                *countp = count;
 651         return 0;
 652 }