sys/kern/link_elf.c

   1 /*-
   2  * Copyright (c) 1998 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_elf.c,v 1.24 1999/12/24 15:33:36 bde Exp $
  27  * $DragonFly: src/sys/kern/link_elf.c,v 1.17 2005/03/04 00:01:30 dillon Exp $
  28  */
  29
  30 #include <sys/param.h>
  31 #include <sys/kernel.h>
  32 #include <sys/systm.h>
  33 #include <sys/malloc.h>
  34 #include <sys/proc.h>
  35 #include <sys/nlookup.h>
  36 #include <sys/fcntl.h>
  37 #include <sys/vnode.h>
  38 #include <sys/linker.h>
  39 #include <machine/elf.h>
  40
  41 #include <vm/vm.h>
  42 #include <vm/vm_param.h>
  43 #include <vm/vm_zone.h>
  44 #include <sys/lock.h>
  45 #ifdef SPARSE_MAPPING
  46 #include <vm/vm_object.h>
  47 #include <vm/vm_kern.h>
  48 #include <vm/vm_extern.h>
  49 #endif
  50 #include <vm/pmap.h>
  51 #include <vm/vm_map.h>
  52
  53 static int      link_elf_load_module(const char*, linker_file_t*);
  54 static int      link_elf_load_file(const char*, linker_file_t*);
  55 static int      link_elf_lookup_symbol(linker_file_t, const char*,
  56                                        c_linker_sym_t*);
  57 static int      link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*);
  58 static int      link_elf_search_symbol(linker_file_t, caddr_t value,
  59                                        c_linker_sym_t* sym, long* diffp);
  60
  61 static void     link_elf_unload_file(linker_file_t);
  62 static void     link_elf_unload_module(linker_file_t);
  63 static int      link_elf_lookup_set(linker_file_t, const char *,
  64                         void ***, void ***, int *);
  65
  66 static struct linker_class_ops link_elf_class_ops = {
  67     link_elf_load_module,
  68 };
  69
  70 static struct linker_file_ops link_elf_file_ops = {
  71     link_elf_lookup_symbol,
  72     link_elf_symbol_values,
  73     link_elf_search_symbol,
  74     link_elf_unload_file,
  75     link_elf_lookup_set
  76 };
  77
  78 static struct linker_file_ops link_elf_module_ops = {
  79     link_elf_lookup_symbol,
  80     link_elf_symbol_values,
  81     link_elf_search_symbol,
  82     link_elf_unload_module,
  83     link_elf_lookup_set
  84 };
  85
  86 typedef struct elf_file {
  87     caddr_t             address;        /* Relocation address */
  88 #ifdef SPARSE_MAPPING
  89     vm_object_t         object;         /* VM object to hold file pages */
  90 #endif
  91     const Elf_Dyn*      dynamic;        /* Symbol table etc. */
  92     Elf_Off             nbuckets;       /* DT_HASH info */
  93     Elf_Off             nchains;
  94     const Elf_Off*      buckets;
  95     const Elf_Off*      chains;
  96     caddr_t             hash;
  97     caddr_t             strtab;         /* DT_STRTAB */
  98     int                 strsz;          /* DT_STRSZ */
  99     const Elf_Sym*      symtab;         /* DT_SYMTAB */
 100     Elf_Addr*           got;            /* DT_PLTGOT */
 101     const Elf_Rel*      pltrel;         /* DT_JMPREL */
 102     int                 pltrelsize;     /* DT_PLTRELSZ */
 103     const Elf_Rela*     pltrela;        /* DT_JMPREL */
 104     int                 pltrelasize;    /* DT_PLTRELSZ */
 105     const Elf_Rel*      rel;            /* DT_REL */
 106     int                 relsize;        /* DT_RELSZ */
 107     const Elf_Rela*     rela;           /* DT_RELA */
 108     int                 relasize;       /* DT_RELASZ */
 109     caddr_t             modptr;
 110     const Elf_Sym*      ddbsymtab;      /* The symbol table we are using */
 111     long                ddbsymcnt;      /* Number of symbols */
 112     caddr_t             ddbstrtab;      /* String table */
 113     long                ddbstrcnt;      /* number of bytes in string table */
 114     caddr_t             symbase;        /* malloc'ed symbold base */
 115     caddr_t             strbase;        /* malloc'ed string base */
 116 } *elf_file_t;
 117
 118 static int              parse_dynamic(linker_file_t lf);
 119 static int              load_dependancies(linker_file_t lf);
 120 static int              relocate_file(linker_file_t lf);
 121 static int              parse_module_symbols(linker_file_t lf);
 122
 123 /*
 124  * The kernel symbol table starts here.
 125  */
 126 extern struct _dynamic _DYNAMIC;
 127
 128 static void
 129 link_elf_init(void* arg)
 130 {
 131     Elf_Dyn     *dp;
 132     caddr_t     modptr, baseptr, sizeptr;
 133     elf_file_t  ef;
 134     char        *modname;
 135
 136 #if ELF_TARG_CLASS == ELFCLASS32
 137     linker_add_class("elf32", NULL, &link_elf_class_ops);
 138 #else
 139     linker_add_class("elf64", NULL, &link_elf_class_ops);
 140 #endif
 141
 142     dp = (Elf_Dyn*) &_DYNAMIC;
 143     if (dp) {
 144         ef = malloc(sizeof(struct elf_file), M_LINKER, M_INTWAIT | M_ZERO);
 145         ef->address = 0;
 146 #ifdef SPARSE_MAPPING
 147         ef->object = 0;
 148 #endif
 149         ef->dynamic = dp;
 150         modname = NULL;
 151         modptr = preload_search_by_type("elf kernel");
 152         if (modptr)
 153             modname = (char *)preload_search_info(modptr, MODINFO_NAME);
 154         if (modname == NULL)
 155             modname = "kernel";
 156         linker_kernel_file = linker_make_file(modname, ef, &link_elf_file_ops);
 157         if (linker_kernel_file == NULL)
 158             panic("link_elf_init: Can't create linker structures for kernel");
 159         parse_dynamic(linker_kernel_file);
 160         linker_kernel_file->address = (caddr_t) KERNBASE;
 161         linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;
 162
 163         if (modptr) {
 164             ef->modptr = modptr;
 165             baseptr = preload_search_info(modptr, MODINFO_ADDR);
 166             if (baseptr)
 167                 linker_kernel_file->address = *(caddr_t *)baseptr;
 168             sizeptr = preload_search_info(modptr, MODINFO_SIZE);
 169             if (sizeptr)
 170                 linker_kernel_file->size = *(size_t *)sizeptr;
 171         }
 172         parse_module_symbols(linker_kernel_file);
 173         linker_current_file = linker_kernel_file;
 174         linker_kernel_file->flags |= LINKER_FILE_LINKED;
 175     }
 176 }
 177
 178 SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0);
 179
 180 static int
 181 parse_module_symbols(linker_file_t lf)
 182 {
 183     elf_file_t ef = lf->priv;
 184     caddr_t     pointer;
 185     caddr_t     ssym, esym, base;
 186     caddr_t     strtab;
 187     int         strcnt;
 188     Elf_Sym*    symtab;
 189     int         symcnt;
 190
 191     if (ef->modptr == NULL)
 192         return 0;
 193     pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM);
 194     if (pointer == NULL)
 195         return 0;
 196     ssym = *(caddr_t *)pointer;
 197     pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM);
 198     if (pointer == NULL)
 199         return 0;
 200     esym = *(caddr_t *)pointer;
 201
 202     base = ssym;
 203
 204     symcnt = *(long *)base;
 205     base += sizeof(long);
 206     symtab = (Elf_Sym *)base;
 207     base += roundup(symcnt, sizeof(long));
 208
 209     if (base > esym || base < ssym) {
 210         printf("Symbols are corrupt!\n");
 211         return EINVAL;
 212     }
 213
 214     strcnt = *(long *)base;
 215     base += sizeof(long);
 216     strtab = base;
 217     base += roundup(strcnt, sizeof(long));
 218
 219     if (base > esym || base < ssym) {
 220         printf("Symbols are corrupt!\n");
 221         return EINVAL;
 222     }
 223
 224     ef->ddbsymtab = symtab;
 225     ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
 226     ef->ddbstrtab = strtab;
 227     ef->ddbstrcnt = strcnt;
 228
 229     return 0;
 230 }
 231
 232 static int
 233 parse_dynamic(linker_file_t lf)
 234 {
 235     elf_file_t ef = lf->priv;
 236     const Elf_Dyn *dp;
 237     int plttype = DT_REL;
 238
 239     for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
 240         switch (dp->d_tag) {
 241         case DT_HASH:
 242         {
 243             /* From src/libexec/rtld-elf/rtld.c */
 244             const Elf_Off *hashtab = (const Elf_Off *)
 245                 (ef->address + dp->d_un.d_ptr);
 246             ef->nbuckets = hashtab[0];
 247             ef->nchains = hashtab[1];
 248             ef->buckets = hashtab + 2;
 249             ef->chains = ef->buckets + ef->nbuckets;
 250             break;
 251         }
 252         case DT_STRTAB:
 253             ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr);
 254             break;
 255         case DT_STRSZ:
 256             ef->strsz = dp->d_un.d_val;
 257             break;
 258         case DT_SYMTAB:
 259             ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr);
 260             break;
 261         case DT_SYMENT:
 262             if (dp->d_un.d_val != sizeof(Elf_Sym))
 263                 return ENOEXEC;
 264             break;
 265         case DT_PLTGOT:
 266             ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr);
 267             break;
 268         case DT_REL:
 269             ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
 270             break;
 271         case DT_RELSZ:
 272             ef->relsize = dp->d_un.d_val;
 273             break;
 274         case DT_RELENT:
 275             if (dp->d_un.d_val != sizeof(Elf_Rel))
 276                 return ENOEXEC;
 277             break;
 278         case DT_JMPREL:
 279             ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
 280             break;
 281         case DT_PLTRELSZ:
 282             ef->pltrelsize = dp->d_un.d_val;
 283             break;
 284         case DT_RELA:
 285             ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr);
 286             break;
 287         case DT_RELASZ:
 288             ef->relasize = dp->d_un.d_val;
 289             break;
 290         case DT_RELAENT:
 291             if (dp->d_un.d_val != sizeof(Elf_Rela))
 292                 return ENOEXEC;
 293             break;
 294         case DT_PLTREL:
 295             plttype = dp->d_un.d_val;
 296             if (plttype != DT_REL && plttype != DT_RELA)
 297                 return ENOEXEC;
 298             break;
 299         }
 300     }
 301
 302     if (plttype == DT_RELA) {
 303         ef->pltrela = (const Elf_Rela *) ef->pltrel;
 304         ef->pltrel = NULL;
 305         ef->pltrelasize = ef->pltrelsize;
 306         ef->pltrelsize = 0;
 307     }
 308
 309     ef->ddbsymtab = ef->symtab;
 310     ef->ddbsymcnt = ef->nchains;
 311     ef->ddbstrtab = ef->strtab;
 312     ef->ddbstrcnt = ef->strsz;
 313
 314     return 0;
 315 }
 316
 317 static void
 318 link_elf_error(const char *s)
 319 {
 320     printf("kldload: %s\n", s);
 321 }
 322
 323 static int
 324 link_elf_load_module(const char *filename, linker_file_t *result)
 325 {
 326     caddr_t             modptr, baseptr, sizeptr, dynptr;
 327     char                *type;
 328     elf_file_t          ef;
 329     linker_file_t       lf;
 330     int                 error;
 331     vm_offset_t         dp;
 332
 333     /*
 334      * Look to see if we have the module preloaded.
 335      */
 336     modptr = preload_search_by_name(filename);
 337     if (modptr == NULL)
 338         return (link_elf_load_file(filename, result));
 339
 340     /* It's preloaded, check we can handle it and collect information */
 341     type = (char *)preload_search_info(modptr, MODINFO_TYPE);
 342     baseptr = preload_search_info(modptr, MODINFO_ADDR);
 343     sizeptr = preload_search_info(modptr, MODINFO_SIZE);
 344     dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC);
 345     if (type == NULL || strcmp(type, "elf module") != 0)
 346         return (EFTYPE);
 347     if (baseptr == NULL || sizeptr == NULL || dynptr == NULL)
 348         return (EINVAL);
 349
 350     ef = malloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO);
 351     if (ef == NULL)
 352         return (ENOMEM);
 353     ef->modptr = modptr;
 354     ef->address = *(caddr_t *)baseptr;
 355 #ifdef SPARSE_MAPPING
 356     ef->object = 0;
 357 #endif
 358     dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
 359     ef->dynamic = (Elf_Dyn *)dp;
 360     lf = linker_make_file(filename, ef, &link_elf_module_ops);
 361     if (lf == NULL) {
 362         free(ef, M_LINKER);
 363         return ENOMEM;
 364     }
 365     lf->address = ef->address;
 366     lf->size = *(size_t *)sizeptr;
 367
 368     error = parse_dynamic(lf);
 369     if (error) {
 370         linker_file_unload(lf);
 371         return error;
 372     }
 373     error = load_dependancies(lf);
 374     if (error) {
 375         linker_file_unload(lf);
 376         return error;
 377     }
 378     error = relocate_file(lf);
 379     if (error) {
 380         linker_file_unload(lf);
 381         return error;
 382     }
 383     parse_module_symbols(lf);
 384     lf->flags |= LINKER_FILE_LINKED;
 385     *result = lf;
 386     return (0);
 387 }
 388
 389 static int
 390 link_elf_load_file(const char* filename, linker_file_t* result)
 391 {
 392     struct nlookupdata nd;
 393     struct thread *td = curthread;      /* XXX */
 394     struct proc *p = td->td_proc;
 395     struct vnode *vp;
 396     Elf_Ehdr *hdr;
 397     caddr_t firstpage;
 398     int nbytes, i;
 399     Elf_Phdr *phdr;
 400     Elf_Phdr *phlimit;
 401     Elf_Phdr *segs[2];
 402     int nsegs;
 403     Elf_Phdr *phdyn;
 404     Elf_Phdr *phphdr;
 405     caddr_t mapbase;
 406     size_t mapsize;
 407     Elf_Off base_offset;
 408     Elf_Addr base_vaddr;
 409     Elf_Addr base_vlimit;
 410     int error = 0;
 411     int resid;
 412     elf_file_t ef;
 413     linker_file_t lf;
 414     char *pathname;
 415     Elf_Shdr *shdr;
 416     int symtabindex;
 417     int symstrindex;
 418     int symcnt;
 419     int strcnt;
 420
 421     KKASSERT(p != NULL);
 422     if (p->p_ucred == NULL) {
 423         printf("link_elf_load_file: cannot load '%s' from filesystem"
 424                 " this early\n", filename);
 425         return ENOENT;
 426     }
 427     shdr = NULL;
 428     lf = NULL;
 429     pathname = linker_search_path(filename);
 430     if (pathname == NULL)
 431         return ENOENT;
 432
 433     error = nlookup_init(&nd, pathname, UIO_SYSSPACE, NLC_FOLLOW|NLC_LOCKVP);
 434     if (error == 0)
 435         error = vn_open(&nd, NULL, FREAD, 0);
 436     free(pathname, M_LINKER);
 437     if (error) {
 438         nlookup_done(&nd);
 439         return error;
 440     }
 441     vp = nd.nl_open_vp;
 442     nd.nl_open_vp = NULL;
 443     nlookup_done(&nd);
 444
 445     /*
 446      * Read the elf header from the file.
 447      */
 448     firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK);
 449     if (firstpage == NULL) {
 450         error = ENOMEM;
 451         goto out;
 452     }
 453     hdr = (Elf_Ehdr *)firstpage;
 454     error = vn_rdwr(UIO_READ, vp, firstpage, PAGE_SIZE, 0,
 455                     UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, td);
 456     nbytes = PAGE_SIZE - resid;
 457     if (error)
 458         goto out;
 459
 460     if (!IS_ELF(*hdr)) {
 461         error = ENOEXEC;
 462         goto out;
 463     }
 464
 465     if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS
 466       || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
 467         link_elf_error("Unsupported file layout");
 468         error = ENOEXEC;
 469         goto out;
 470     }
 471     if (hdr->e_ident[EI_VERSION] != EV_CURRENT
 472       || hdr->e_version != EV_CURRENT) {
 473         link_elf_error("Unsupported file version");
 474         error = ENOEXEC;
 475         goto out;
 476     }
 477     if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
 478         link_elf_error("Unsupported file type");
 479         error = ENOEXEC;
 480         goto out;
 481     }
 482     if (hdr->e_machine != ELF_TARG_MACH) {
 483         link_elf_error("Unsupported machine");
 484         error = ENOEXEC;
 485         goto out;
 486     }
 487
 488     /*
 489      * We rely on the program header being in the first page.  This is
 490      * not strictly required by the ABI specification, but it seems to
 491      * always true in practice.  And, it simplifies things considerably.
 492      */
 493     if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
 494           (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
 495           (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
 496         link_elf_error("Unreadable program headers");
 497
 498     /*
 499      * Scan the program header entries, and save key information.
 500      *
 501      * We rely on there being exactly two load segments, text and data,
 502      * in that order.
 503      */
 504     phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
 505     phlimit = phdr + hdr->e_phnum;
 506     nsegs = 0;
 507     phdyn = NULL;
 508     phphdr = NULL;
 509     while (phdr < phlimit) {
 510         switch (phdr->p_type) {
 511
 512         case PT_LOAD:
 513             if (nsegs == 2) {
 514                 link_elf_error("Too many sections");
 515                 error = ENOEXEC;
 516                 goto out;
 517             }
 518             segs[nsegs] = phdr;
 519             ++nsegs;
 520             break;
 521
 522         case PT_PHDR:
 523             phphdr = phdr;
 524             break;
 525
 526         case PT_DYNAMIC:
 527             phdyn = phdr;
 528             break;
 529         }
 530
 531         ++phdr;
 532     }
 533     if (phdyn == NULL) {
 534         link_elf_error("Object is not dynamically-linked");
 535         error = ENOEXEC;
 536         goto out;
 537     }
 538
 539     /*
 540      * Allocate the entire address space of the object, to stake out our
 541      * contiguous region, and to establish the base address for relocation.
 542      */
 543     base_offset = trunc_page(segs[0]->p_offset);
 544     base_vaddr = trunc_page(segs[0]->p_vaddr);
 545     base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz);
 546     mapsize = base_vlimit - base_vaddr;
 547
 548     ef = malloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO);
 549 #ifdef SPARSE_MAPPING
 550     ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
 551     if (ef->object == NULL) {
 552         free(ef, M_LINKER);
 553         error = ENOMEM;
 554         goto out;
 555     }
 556     vm_object_reference(ef->object);
 557     ef->address = (caddr_t) vm_map_min(kernel_map);
 558     error = vm_map_find(kernel_map, ef->object, 0,
 559                         (vm_offset_t *) &ef->address,
 560                         mapsize, 1,
 561                         VM_PROT_ALL, VM_PROT_ALL, 0);
 562     if (error) {
 563         vm_object_deallocate(ef->object);
 564         free(ef, M_LINKER);
 565         goto out;
 566     }
 567 #else
 568     ef->address = malloc(mapsize, M_LINKER, M_WAITOK);
 569 #endif
 570     mapbase = ef->address;
 571
 572     /*
 573      * Read the text and data sections and zero the bss.
 574      */
 575     for (i = 0; i < 2; i++) {
 576         caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
 577         error = vn_rdwr(UIO_READ, vp,
 578                         segbase, segs[i]->p_filesz, segs[i]->p_offset,
 579                         UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, td);
 580         if (error) {
 581 #ifdef SPARSE_MAPPING
 582             vm_map_remove(kernel_map, (vm_offset_t) ef->address,
 583                           (vm_offset_t) ef->address
 584                           + (ef->object->size << PAGE_SHIFT));
 585             vm_object_deallocate(ef->object);
 586 #else
 587             free(ef->address, M_LINKER);
 588 #endif
 589             free(ef, M_LINKER);
 590             goto out;
 591         }
 592         bzero(segbase + segs[i]->p_filesz,
 593               segs[i]->p_memsz - segs[i]->p_filesz);
 594
 595 #ifdef SPARSE_MAPPING
 596         /*
 597          * Wire down the pages
 598          */
 599         vm_map_wire(kernel_map,
 600                         (vm_offset_t) segbase,
 601                         (vm_offset_t) segbase + segs[i]->p_memsz,
 602                         0);
 603 #endif
 604     }
 605
 606     ef->dynamic = (const Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
 607
 608     lf = linker_make_file(filename, ef, &link_elf_file_ops);
 609     if (lf == NULL) {
 610 #ifdef SPARSE_MAPPING
 611         vm_map_remove(kernel_map, (vm_offset_t) ef->address,
 612                       (vm_offset_t) ef->address
 613                       + (ef->object->size << PAGE_SHIFT));
 614         vm_object_deallocate(ef->object);
 615 #else
 616         free(ef->address, M_LINKER);
 617 #endif
 618         free(ef, M_LINKER);
 619         error = ENOMEM;
 620         goto out;
 621     }
 622     lf->address = ef->address;
 623     lf->size = mapsize;
 624
 625     error = parse_dynamic(lf);
 626     if (error)
 627         goto out;
 628     error = load_dependancies(lf);
 629     if (error)
 630         goto out;
 631     error = relocate_file(lf);
 632     if (error)
 633         goto out;
 634
 635     /* Try and load the symbol table if it's present.  (you can strip it!) */
 636     nbytes = hdr->e_shnum * hdr->e_shentsize;
 637     if (nbytes == 0 || hdr->e_shoff == 0)
 638         goto nosyms;
 639     shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
 640     if (shdr == NULL) {
 641         error = ENOMEM;
 642         goto out;
 643     }
 644     error = vn_rdwr(UIO_READ, vp,
 645                     (caddr_t)shdr, nbytes, hdr->e_shoff,
 646                     UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, td);
 647     if (error)
 648         goto out;
 649     symtabindex = -1;
 650     symstrindex = -1;
 651     for (i = 0; i < hdr->e_shnum; i++) {
 652         if (shdr[i].sh_type == SHT_SYMTAB) {
 653             symtabindex = i;
 654             symstrindex = shdr[i].sh_link;
 655         }
 656     }
 657     if (symtabindex < 0 || symstrindex < 0)
 658         goto nosyms;
 659
 660     symcnt = shdr[symtabindex].sh_size;
 661     ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK);
 662     strcnt = shdr[symstrindex].sh_size;
 663     ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK);
 664
 665     if (ef->symbase == NULL || ef->strbase == NULL) {
 666         error = ENOMEM;
 667         goto out;
 668     }
 669     error = vn_rdwr(UIO_READ, vp,
 670                     ef->symbase, symcnt, shdr[symtabindex].sh_offset,
 671                     UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, td);
 672     if (error)
 673         goto out;
 674     error = vn_rdwr(UIO_READ, vp,
 675                     ef->strbase, strcnt, shdr[symstrindex].sh_offset,
 676                     UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, td);
 677     if (error)
 678         goto out;
 679
 680     ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
 681     ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
 682     ef->ddbstrcnt = strcnt;
 683     ef->ddbstrtab = ef->strbase;
 684
 685     lf->flags |= LINKER_FILE_LINKED;
 686
 687 nosyms:
 688
 689     *result = lf;
 690
 691 out:
 692     if (error && lf)
 693         linker_file_unload(lf);
 694     if (shdr)
 695         free(shdr, M_LINKER);
 696     if (firstpage)
 697         free(firstpage, M_LINKER);
 698     VOP_UNLOCK(vp, 0, td);
 699     vn_close(vp, FREAD, td);
 700
 701     return error;
 702 }
 703
 704 static void
 705 link_elf_unload_file(linker_file_t file)
 706 {
 707     elf_file_t ef = file->priv;
 708
 709     if (ef) {
 710 #ifdef SPARSE_MAPPING
 711         if (ef->object) {
 712             vm_map_remove(kernel_map, (vm_offset_t) ef->address,
 713                           (vm_offset_t) ef->address
 714                           + (ef->object->size << PAGE_SHIFT));
 715             vm_object_deallocate(ef->object);
 716         }
 717 #else
 718         if (ef->address)
 719             free(ef->address, M_LINKER);
 720 #endif
 721         if (ef->symbase)
 722             free(ef->symbase, M_LINKER);
 723         if (ef->strbase)
 724             free(ef->strbase, M_LINKER);
 725         free(ef, M_LINKER);
 726     }
 727 }
 728
 729 static void
 730 link_elf_unload_module(linker_file_t file)
 731 {
 732     elf_file_t ef = file->priv;
 733
 734     if (ef)
 735         free(ef, M_LINKER);
 736     if (file->filename)
 737         preload_delete_name(file->filename);
 738 }
 739
 740 static int
 741 load_dependancies(linker_file_t lf)
 742 {
 743     elf_file_t ef = lf->priv;
 744     linker_file_t lfdep;
 745     char* name;
 746     const Elf_Dyn *dp;
 747     int error = 0;
 748
 749     /*
 750      * All files are dependant on /kernel.
 751      */
 752     if (linker_kernel_file) {
 753         linker_kernel_file->refs++;
 754         linker_file_add_dependancy(lf, linker_kernel_file);
 755     }
 756
 757     for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
 758         if (dp->d_tag == DT_NEEDED) {
 759             name = ef->strtab + dp->d_un.d_val;
 760
 761             error = linker_load_file(name, &lfdep);
 762             if (error)
 763                 goto out;
 764             error = linker_file_add_dependancy(lf, lfdep);
 765             if (error)
 766                 goto out;
 767         }
 768     }
 769
 770 out:
 771     return error;
 772 }
 773
 774 static const char *
 775 symbol_name(elf_file_t ef, Elf_Word r_info)
 776 {
 777     const Elf_Sym *ref;
 778
 779     if (ELF_R_SYM(r_info)) {
 780         ref = ef->symtab + ELF_R_SYM(r_info);
 781         return ef->strtab + ref->st_name;
 782     } else
 783         return NULL;
 784 }
 785
 786 static int
 787 relocate_file(linker_file_t lf)
 788 {
 789     elf_file_t ef = lf->priv;
 790     const Elf_Rel *rellim;
 791     const Elf_Rel *rel;
 792     const Elf_Rela *relalim;
 793     const Elf_Rela *rela;
 794     const char *symname;
 795
 796     /* Perform relocations without addend if there are any: */
 797     rel = ef->rel;
 798     if (rel) {
 799         rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
 800         while (rel < rellim) {
 801             symname = symbol_name(ef, rel->r_info);
 802             if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) {
 803                 printf("link_elf: symbol %s undefined\n", symname);
 804                 return ENOENT;
 805             }
 806             rel++;
 807         }
 808     }
 809
 810     /* Perform relocations with addend if there are any: */
 811     rela = ef->rela;
 812     if (rela) {
 813         relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
 814         while (rela < relalim) {
 815             symname = symbol_name(ef, rela->r_info);
 816             if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) {
 817                 printf("link_elf: symbol %s undefined\n", symname);
 818                 return ENOENT;
 819             }
 820             rela++;
 821         }
 822     }
 823
 824     /* Perform PLT relocations without addend if there are any: */
 825     rel = ef->pltrel;
 826     if (rel) {
 827         rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize);
 828         while (rel < rellim) {
 829             symname = symbol_name(ef, rel->r_info);
 830             if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) {
 831                 printf("link_elf: symbol %s undefined\n", symname);
 832                 return ENOENT;
 833             }
 834             rel++;
 835         }
 836     }
 837
 838     /* Perform relocations with addend if there are any: */
 839     rela = ef->pltrela;
 840     if (rela) {
 841         relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize);
 842         while (rela < relalim) {
 843             symname = symbol_name(ef, rela->r_info);
 844             if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) {
 845                 printf("link_elf: symbol %s undefined\n", symname);
 846                 return ENOENT;
 847             }
 848             rela++;
 849         }
 850     }
 851
 852     return 0;
 853 }
 854
 855 /*
 856  * Hash function for symbol table lookup.  Don't even think about changing
 857  * this.  It is specified by the System V ABI.
 858  */
 859 static unsigned long
 860 elf_hash(const char *name)
 861 {
 862     const unsigned char *p = (const unsigned char *) name;
 863     unsigned long h = 0;
 864     unsigned long g;
 865
 866     while (*p != '\0') {
 867         h = (h << 4) + *p++;
 868         if ((g = h & 0xf0000000) != 0)
 869             h ^= g >> 24;
 870         h &= ~g;
 871     }
 872     return h;
 873 }
 874
 875 int
 876 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym)
 877 {
 878     elf_file_t ef = lf->priv;
 879     unsigned long symnum;
 880     const Elf_Sym* symp;
 881     const char *strp;
 882     unsigned long hash;
 883     int i;
 884
 885     /* First, search hashed global symbols */
 886     hash = elf_hash(name);
 887     symnum = ef->buckets[hash % ef->nbuckets];
 888
 889     while (symnum != STN_UNDEF) {
 890         if (symnum >= ef->nchains) {
 891             printf("link_elf_lookup_symbol: corrupt symbol table\n");
 892             return ENOENT;
 893         }
 894
 895         symp = ef->symtab + symnum;
 896         if (symp->st_name == 0) {
 897             printf("link_elf_lookup_symbol: corrupt symbol table\n");
 898             return ENOENT;
 899         }
 900
 901         strp = ef->strtab + symp->st_name;
 902
 903         if (strcmp(name, strp) == 0) {
 904             if (symp->st_shndx != SHN_UNDEF ||
 905                 (symp->st_value != 0 &&
 906                  ELF_ST_TYPE(symp->st_info) == STT_FUNC)
 907              ) {
 908                 *sym = (c_linker_sym_t) symp;
 909                 return 0;
 910             } else {
 911                 return ENOENT;
 912             }
 913         }
 914
 915         symnum = ef->chains[symnum];
 916     }
 917
 918     /* If we have not found it, look at the full table (if loaded) */
 919     if (ef->symtab == ef->ddbsymtab)
 920         return ENOENT;
 921
 922     /* Exhaustive search */
 923     for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
 924         strp = ef->ddbstrtab + symp->st_name;
 925         if (strcmp(name, strp) == 0) {
 926             if (symp->st_shndx != SHN_UNDEF ||
 927                 (symp->st_value != 0 &&
 928                  ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
 929                 *sym = (c_linker_sym_t) symp;
 930                 return 0;
 931             } else {
 932                 return ENOENT;
 933             }
 934         }
 935     }
 936     return ENOENT;
 937 }
 938
 939 static int
 940 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval)
 941 {
 942         elf_file_t ef = lf->priv;
 943         const Elf_Sym* es = (const Elf_Sym*) sym;
 944
 945         if (es >= ef->symtab && ((es - ef->symtab) < ef->nchains)) {
 946             symval->name = ef->strtab + es->st_name;
 947             symval->value = (caddr_t) ef->address + es->st_value;
 948             symval->size = es->st_size;
 949             return 0;
 950         }
 951         if (ef->symtab == ef->ddbsymtab)
 952             return ENOENT;
 953         if (es >= ef->ddbsymtab && ((es - ef->ddbsymtab) < ef->ddbsymcnt)) {
 954             symval->name = ef->ddbstrtab + es->st_name;
 955             symval->value = (caddr_t) ef->address + es->st_value;
 956             symval->size = es->st_size;
 957             return 0;
 958         }
 959         return ENOENT;
 960 }
 961
 962 static int
 963 link_elf_search_symbol(linker_file_t lf, caddr_t value,
 964                        c_linker_sym_t* sym, long* diffp)
 965 {
 966         elf_file_t ef = lf->priv;
 967         u_long off = (uintptr_t) (void *) value;
 968         u_long diff = off;
 969         u_long st_value;
 970         const Elf_Sym* es;
 971         const Elf_Sym* best = 0;
 972         int i;
 973
 974         for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
 975                 if (es->st_name == 0)
 976                         continue;
 977                 st_value = es->st_value + (uintptr_t) (void *) ef->address;
 978                 if (off >= st_value) {
 979                         if (off - st_value < diff) {
 980                                 diff = off - st_value;
 981                                 best = es;
 982                                 if (diff == 0)
 983                                         break;
 984                         } else if (off - st_value == diff) {
 985                                 best = es;
 986                         }
 987                 }
 988         }
 989         if (best == 0)
 990                 *diffp = off;
 991         else
 992                 *diffp = diff;
 993         *sym = (c_linker_sym_t) best;
 994
 995         return 0;
 996 }
 997
 998 /*
 999  * Look up a linker set on an ELF system.
1000  */
1001 static int
1002 link_elf_lookup_set(linker_file_t lf, const char *name,
1003                 void ***startp, void ***stopp, int *countp)
1004 {
1005         c_linker_sym_t sym;
1006         linker_symval_t symval;
1007         char *setsym;
1008         void **start, **stop;
1009         int len, error = 0, count;
1010
1011         len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
1012         setsym = malloc(len, M_LINKER, M_WAITOK);
1013         if (setsym == NULL)
1014                return ENOMEM;
1015
1016         /* get address of first entry */
1017         snprintf(setsym, len, "%s%s", "__start_set_", name);
1018         error = link_elf_lookup_symbol(lf, setsym, &sym);
1019         if (error)
1020                goto out;
1021         link_elf_symbol_values(lf, sym, &symval);
1022         if (symval.value == 0) {
1023                error = ESRCH;
1024                goto out;
1025         }
1026         start = (void **)symval.value;
1027
1028         /* get address of last entry */
1029         snprintf(setsym, len, "%s%s", "__stop_set_", name);
1030         error = link_elf_lookup_symbol(lf, setsym, &sym);
1031         if (error)
1032                goto out;
1033         link_elf_symbol_values(lf, sym, &symval);
1034         if (symval.value == 0) {
1035                error = ESRCH;
1036                goto out;
1037         }
1038         stop = (void **)symval.value;
1039
1040         /* and the number of entries */
1041         count = stop - start;
1042
1043         /* and copy out */
1044         if (startp)
1045                *startp = start;
1046         if (stopp)
1047                *stopp = stop;
1048         if (countp)
1049                *countp = count;
1050
1051         out:
1052         free(setsym, M_LINKER);
1053         return error;
1054 }
1055