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 1.28 2008/02/06 22:37:46 nth 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 = kmalloc(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_BOOT2_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         kprintf("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         kprintf("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     kprintf("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 = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO);
 351     ef->modptr = modptr;
 352     ef->address = *(caddr_t *)baseptr;
 353 #ifdef SPARSE_MAPPING
 354     ef->object = 0;
 355 #endif
 356     dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
 357     ef->dynamic = (Elf_Dyn *)dp;
 358     lf = linker_make_file(filename, ef, &link_elf_module_ops);
 359     if (lf == NULL) {
 360         kfree(ef, M_LINKER);
 361         return ENOMEM;
 362     }
 363     lf->address = ef->address;
 364     lf->size = *(size_t *)sizeptr;
 365
 366     error = parse_dynamic(lf);
 367     if (error) {
 368         linker_file_unload(lf);
 369         return error;
 370     }
 371     error = load_dependancies(lf);
 372     if (error) {
 373         linker_file_unload(lf);
 374         return error;
 375     }
 376     error = relocate_file(lf);
 377     if (error) {
 378         linker_file_unload(lf);
 379         return error;
 380     }
 381     parse_module_symbols(lf);
 382     lf->flags |= LINKER_FILE_LINKED;
 383     *result = lf;
 384     return (0);
 385 }
 386
 387 static int
 388 link_elf_load_file(const char* filename, linker_file_t* result)
 389 {
 390     struct nlookupdata nd;
 391     struct thread *td = curthread;      /* XXX */
 392     struct proc *p = td->td_proc;
 393     struct vnode *vp;
 394     Elf_Ehdr *hdr;
 395     caddr_t firstpage;
 396     int nbytes, i;
 397     Elf_Phdr *phdr;
 398     Elf_Phdr *phlimit;
 399     Elf_Phdr *segs[2];
 400     int nsegs;
 401     Elf_Phdr *phdyn;
 402     Elf_Phdr *phphdr;
 403     caddr_t mapbase;
 404     size_t mapsize;
 405     Elf_Off base_offset;
 406     Elf_Addr base_vaddr;
 407     Elf_Addr base_vlimit;
 408     int error = 0;
 409     int resid;
 410     elf_file_t ef;
 411     linker_file_t lf;
 412     char *pathname;
 413     Elf_Shdr *shdr;
 414     int symtabindex;
 415     int symstrindex;
 416     int symcnt;
 417     int strcnt;
 418
 419     KKASSERT(p != NULL);
 420     if (p->p_ucred == NULL) {
 421         kprintf("link_elf_load_file: cannot load '%s' from filesystem"
 422                 " this early\n", filename);
 423         return ENOENT;
 424     }
 425     shdr = NULL;
 426     lf = NULL;
 427     pathname = linker_search_path(filename);
 428     if (pathname == NULL)
 429         return ENOENT;
 430
 431     error = nlookup_init(&nd, pathname, UIO_SYSSPACE, NLC_FOLLOW|NLC_LOCKVP);
 432     if (error == 0)
 433         error = vn_open(&nd, NULL, FREAD, 0);
 434     kfree(pathname, M_LINKER);
 435     if (error) {
 436         nlookup_done(&nd);
 437         return error;
 438     }
 439     vp = nd.nl_open_vp;
 440     nd.nl_open_vp = NULL;
 441     nlookup_done(&nd);
 442
 443     /*
 444      * Read the elf header from the file.
 445      */
 446     firstpage = kmalloc(PAGE_SIZE, M_LINKER, M_WAITOK);
 447     hdr = (Elf_Ehdr *)firstpage;
 448     error = vn_rdwr(UIO_READ, vp, firstpage, PAGE_SIZE, 0,
 449                     UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid);
 450     nbytes = PAGE_SIZE - resid;
 451     if (error)
 452         goto out;
 453
 454     if (!IS_ELF(*hdr)) {
 455         error = ENOEXEC;
 456         goto out;
 457     }
 458
 459     if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS
 460       || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
 461         link_elf_error("Unsupported file layout");
 462         error = ENOEXEC;
 463         goto out;
 464     }
 465     if (hdr->e_ident[EI_VERSION] != EV_CURRENT
 466       || hdr->e_version != EV_CURRENT) {
 467         link_elf_error("Unsupported file version");
 468         error = ENOEXEC;
 469         goto out;
 470     }
 471     if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
 472         link_elf_error("Unsupported file type");
 473         error = ENOEXEC;
 474         goto out;
 475     }
 476     if (hdr->e_machine != ELF_TARG_MACH) {
 477         link_elf_error("Unsupported machine");
 478         error = ENOEXEC;
 479         goto out;
 480     }
 481
 482     /*
 483      * We rely on the program header being in the first page.  This is
 484      * not strictly required by the ABI specification, but it seems to
 485      * always true in practice.  And, it simplifies things considerably.
 486      */
 487     if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
 488           (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
 489           (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
 490         link_elf_error("Unreadable program headers");
 491
 492     /*
 493      * Scan the program header entries, and save key information.
 494      *
 495      * We rely on there being exactly two load segments, text and data,
 496      * in that order.
 497      */
 498     phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
 499     phlimit = phdr + hdr->e_phnum;
 500     nsegs = 0;
 501     phdyn = NULL;
 502     phphdr = NULL;
 503     while (phdr < phlimit) {
 504         switch (phdr->p_type) {
 505
 506         case PT_LOAD:
 507             if (nsegs == 2) {
 508                 link_elf_error("Too many sections");
 509                 error = ENOEXEC;
 510                 goto out;
 511             }
 512             segs[nsegs] = phdr;
 513             ++nsegs;
 514             break;
 515
 516         case PT_PHDR:
 517             phphdr = phdr;
 518             break;
 519
 520         case PT_DYNAMIC:
 521             phdyn = phdr;
 522             break;
 523         }
 524
 525         ++phdr;
 526     }
 527     if (phdyn == NULL) {
 528         link_elf_error("Object is not dynamically-linked");
 529         error = ENOEXEC;
 530         goto out;
 531     }
 532
 533     /*
 534      * Allocate the entire address space of the object, to stake out our
 535      * contiguous region, and to establish the base address for relocation.
 536      */
 537     base_offset = trunc_page(segs[0]->p_offset);
 538     base_vaddr = trunc_page(segs[0]->p_vaddr);
 539     base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz);
 540     mapsize = base_vlimit - base_vaddr;
 541
 542     ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO);
 543 #ifdef SPARSE_MAPPING
 544     ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
 545     if (ef->object == NULL) {
 546         kfree(ef, M_LINKER);
 547         error = ENOMEM;
 548         goto out;
 549     }
 550     vm_object_reference(ef->object);
 551     ef->address = (caddr_t)vm_map_min(&kernel_map);
 552     error = vm_map_find(&kernel_map, ef->object, 0,
 553                         (vm_offset_t *)&ef->address, mapsize,
 554                         1,
 555                         VM_MAPTYPE_NORMAL,
 556                         VM_PROT_ALL, VM_PROT_ALL,
 557                         0);
 558     if (error) {
 559         vm_object_deallocate(ef->object);
 560         kfree(ef, M_LINKER);
 561         goto out;
 562     }
 563 #else
 564     ef->address = kmalloc(mapsize, M_LINKER, M_WAITOK);
 565 #endif
 566     mapbase = ef->address;
 567
 568     /*
 569      * Read the text and data sections and zero the bss.
 570      */
 571     for (i = 0; i < 2; i++) {
 572         caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
 573         error = vn_rdwr(UIO_READ, vp,
 574                         segbase, segs[i]->p_filesz, segs[i]->p_offset,
 575                         UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid);
 576         if (error) {
 577 #ifdef SPARSE_MAPPING
 578             vm_map_remove(&kernel_map, (vm_offset_t) ef->address,
 579                           (vm_offset_t) ef->address
 580                           + (ef->object->size << PAGE_SHIFT));
 581             vm_object_deallocate(ef->object);
 582 #else
 583             kfree(ef->address, M_LINKER);
 584 #endif
 585             kfree(ef, M_LINKER);
 586             goto out;
 587         }
 588         bzero(segbase + segs[i]->p_filesz,
 589               segs[i]->p_memsz - segs[i]->p_filesz);
 590
 591 #ifdef SPARSE_MAPPING
 592         /*
 593          * Wire down the pages
 594          */
 595         vm_map_wire(&kernel_map,
 596                     (vm_offset_t) segbase,
 597                     (vm_offset_t) segbase + segs[i]->p_memsz,
 598                     0);
 599 #endif
 600     }
 601
 602     ef->dynamic = (const Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
 603
 604     lf = linker_make_file(filename, ef, &link_elf_file_ops);
 605     if (lf == NULL) {
 606 #ifdef SPARSE_MAPPING
 607         vm_map_remove(&kernel_map, (vm_offset_t) ef->address,
 608                       (vm_offset_t) ef->address
 609                       + (ef->object->size << PAGE_SHIFT));
 610         vm_object_deallocate(ef->object);
 611 #else
 612         kfree(ef->address, M_LINKER);
 613 #endif
 614         kfree(ef, M_LINKER);
 615         error = ENOMEM;
 616         goto out;
 617     }
 618     lf->address = ef->address;
 619     lf->size = mapsize;
 620
 621     error = parse_dynamic(lf);
 622     if (error)
 623         goto out;
 624     error = load_dependancies(lf);
 625     if (error)
 626         goto out;
 627     error = relocate_file(lf);
 628     if (error)
 629         goto out;
 630
 631     /* Try and load the symbol table if it's present.  (you can strip it!) */
 632     nbytes = hdr->e_shnum * hdr->e_shentsize;
 633     if (nbytes == 0 || hdr->e_shoff == 0)
 634         goto nosyms;
 635     shdr = kmalloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
 636     error = vn_rdwr(UIO_READ, vp,
 637                     (caddr_t)shdr, nbytes, hdr->e_shoff,
 638                     UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid);
 639     if (error)
 640         goto out;
 641     symtabindex = -1;
 642     symstrindex = -1;
 643     for (i = 0; i < hdr->e_shnum; i++) {
 644         if (shdr[i].sh_type == SHT_SYMTAB) {
 645             symtabindex = i;
 646             symstrindex = shdr[i].sh_link;
 647         }
 648     }
 649     if (symtabindex < 0 || symstrindex < 0)
 650         goto nosyms;
 651
 652     symcnt = shdr[symtabindex].sh_size;
 653     ef->symbase = kmalloc(symcnt, M_LINKER, M_WAITOK);
 654     strcnt = shdr[symstrindex].sh_size;
 655     ef->strbase = kmalloc(strcnt, M_LINKER, M_WAITOK);
 656     error = vn_rdwr(UIO_READ, vp,
 657                     ef->symbase, symcnt, shdr[symtabindex].sh_offset,
 658                     UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid);
 659     if (error)
 660         goto out;
 661     error = vn_rdwr(UIO_READ, vp,
 662                     ef->strbase, strcnt, shdr[symstrindex].sh_offset,
 663                     UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid);
 664     if (error)
 665         goto out;
 666
 667     ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
 668     ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
 669     ef->ddbstrcnt = strcnt;
 670     ef->ddbstrtab = ef->strbase;
 671
 672     lf->flags |= LINKER_FILE_LINKED;
 673
 674 nosyms:
 675
 676     *result = lf;
 677
 678 out:
 679     if (error && lf)
 680         linker_file_unload(lf);
 681     if (shdr)
 682         kfree(shdr, M_LINKER);
 683     if (firstpage)
 684         kfree(firstpage, M_LINKER);
 685     vn_unlock(vp);
 686     vn_close(vp, FREAD);
 687
 688     return error;
 689 }
 690
 691 static void
 692 link_elf_unload_file(linker_file_t file)
 693 {
 694     elf_file_t ef = file->priv;
 695
 696     if (ef) {
 697 #ifdef SPARSE_MAPPING
 698         if (ef->object) {
 699             vm_map_remove(&kernel_map, (vm_offset_t) ef->address,
 700                           (vm_offset_t) ef->address
 701                           + (ef->object->size << PAGE_SHIFT));
 702             vm_object_deallocate(ef->object);
 703         }
 704 #else
 705         if (ef->address)
 706             kfree(ef->address, M_LINKER);
 707 #endif
 708         if (ef->symbase)
 709             kfree(ef->symbase, M_LINKER);
 710         if (ef->strbase)
 711             kfree(ef->strbase, M_LINKER);
 712         kfree(ef, M_LINKER);
 713     }
 714 }
 715
 716 static void
 717 link_elf_unload_module(linker_file_t file)
 718 {
 719     elf_file_t ef = file->priv;
 720
 721     if (ef)
 722         kfree(ef, M_LINKER);
 723     if (file->filename)
 724         preload_delete_name(file->filename);
 725 }
 726
 727 static int
 728 load_dependancies(linker_file_t lf)
 729 {
 730     elf_file_t ef = lf->priv;
 731     linker_file_t lfdep;
 732     char* name;
 733     const Elf_Dyn *dp;
 734     int error = 0;
 735
 736     /*
 737      * All files are dependant on /kernel.
 738      */
 739     if (linker_kernel_file) {
 740         linker_kernel_file->refs++;
 741         linker_file_add_dependancy(lf, linker_kernel_file);
 742     }
 743
 744     for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
 745         if (dp->d_tag == DT_NEEDED) {
 746             name = ef->strtab + dp->d_un.d_val;
 747
 748             error = linker_load_file(name, &lfdep);
 749             if (error)
 750                 goto out;
 751             linker_file_add_dependancy(lf, lfdep);
 752         }
 753     }
 754
 755 out:
 756     return error;
 757 }
 758
 759 static const char *
 760 symbol_name(elf_file_t ef, Elf_Word r_info)
 761 {
 762     const Elf_Sym *ref;
 763
 764     if (ELF_R_SYM(r_info)) {
 765         ref = ef->symtab + ELF_R_SYM(r_info);
 766         return ef->strtab + ref->st_name;
 767     } else
 768         return NULL;
 769 }
 770
 771 static int
 772 relocate_file(linker_file_t lf)
 773 {
 774     elf_file_t ef = lf->priv;
 775     const Elf_Rel *rellim;
 776     const Elf_Rel *rel;
 777     const Elf_Rela *relalim;
 778     const Elf_Rela *rela;
 779     const char *symname;
 780
 781     /* Perform relocations without addend if there are any: */
 782     rel = ef->rel;
 783     if (rel) {
 784         rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
 785         while (rel < rellim) {
 786             symname = symbol_name(ef, rel->r_info);
 787             if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) {
 788                 kprintf("link_elf: symbol %s undefined\n", symname);
 789                 return ENOENT;
 790             }
 791             rel++;
 792         }
 793     }
 794
 795     /* Perform relocations with addend if there are any: */
 796     rela = ef->rela;
 797     if (rela) {
 798         relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
 799         while (rela < relalim) {
 800             symname = symbol_name(ef, rela->r_info);
 801             if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) {
 802                 kprintf("link_elf: symbol %s undefined\n", symname);
 803                 return ENOENT;
 804             }
 805             rela++;
 806         }
 807     }
 808
 809     /* Perform PLT relocations without addend if there are any: */
 810     rel = ef->pltrel;
 811     if (rel) {
 812         rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize);
 813         while (rel < rellim) {
 814             symname = symbol_name(ef, rel->r_info);
 815             if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) {
 816                 kprintf("link_elf: symbol %s undefined\n", symname);
 817                 return ENOENT;
 818             }
 819             rel++;
 820         }
 821     }
 822
 823     /* Perform relocations with addend if there are any: */
 824     rela = ef->pltrela;
 825     if (rela) {
 826         relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize);
 827         while (rela < relalim) {
 828             symname = symbol_name(ef, rela->r_info);
 829             if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) {
 830                 kprintf("link_elf: symbol %s undefined\n", symname);
 831                 return ENOENT;
 832             }
 833             rela++;
 834         }
 835     }
 836
 837     return 0;
 838 }
 839
 840 /*
 841  * Hash function for symbol table lookup.  Don't even think about changing
 842  * this.  It is specified by the System V ABI.
 843  */
 844 static unsigned long
 845 elf_hash(const char *name)
 846 {
 847     const unsigned char *p = (const unsigned char *) name;
 848     unsigned long h = 0;
 849     unsigned long g;
 850
 851     while (*p != '\0') {
 852         h = (h << 4) + *p++;
 853         if ((g = h & 0xf0000000) != 0)
 854             h ^= g >> 24;
 855         h &= ~g;
 856     }
 857     return h;
 858 }
 859
 860 int
 861 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym)
 862 {
 863     elf_file_t ef = lf->priv;
 864     unsigned long symnum;
 865     const Elf_Sym* symp;
 866     const char *strp;
 867     unsigned long hash;
 868     int i;
 869
 870     /* First, search hashed global symbols */
 871     hash = elf_hash(name);
 872     symnum = ef->buckets[hash % ef->nbuckets];
 873
 874     while (symnum != STN_UNDEF) {
 875         if (symnum >= ef->nchains) {
 876             kprintf("link_elf_lookup_symbol: corrupt symbol table\n");
 877             return ENOENT;
 878         }
 879
 880         symp = ef->symtab + symnum;
 881         if (symp->st_name == 0) {
 882             kprintf("link_elf_lookup_symbol: corrupt symbol table\n");
 883             return ENOENT;
 884         }
 885
 886         strp = ef->strtab + symp->st_name;
 887
 888         if (strcmp(name, strp) == 0) {
 889             if (symp->st_shndx != SHN_UNDEF ||
 890                 (symp->st_value != 0 &&
 891                  ELF_ST_TYPE(symp->st_info) == STT_FUNC)
 892              ) {
 893                 *sym = (c_linker_sym_t) symp;
 894                 return 0;
 895             } else {
 896                 return ENOENT;
 897             }
 898         }
 899
 900         symnum = ef->chains[symnum];
 901     }
 902
 903     /* If we have not found it, look at the full table (if loaded) */
 904     if (ef->symtab == ef->ddbsymtab)
 905         return ENOENT;
 906
 907     /* Exhaustive search */
 908     for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
 909         strp = ef->ddbstrtab + symp->st_name;
 910         if (strcmp(name, strp) == 0) {
 911             if (symp->st_shndx != SHN_UNDEF ||
 912                 (symp->st_value != 0 &&
 913                  ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
 914                 *sym = (c_linker_sym_t) symp;
 915                 return 0;
 916             } else {
 917                 return ENOENT;
 918             }
 919         }
 920     }
 921     return ENOENT;
 922 }
 923
 924 static int
 925 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval)
 926 {
 927         elf_file_t ef = lf->priv;
 928         const Elf_Sym* es = (const Elf_Sym*) sym;
 929
 930         if (es >= ef->symtab && ((es - ef->symtab) < ef->nchains)) {
 931             symval->name = ef->strtab + es->st_name;
 932             symval->value = (caddr_t) ef->address + es->st_value;
 933             symval->size = es->st_size;
 934             return 0;
 935         }
 936         if (ef->symtab == ef->ddbsymtab)
 937             return ENOENT;
 938         if (es >= ef->ddbsymtab && ((es - ef->ddbsymtab) < ef->ddbsymcnt)) {
 939             symval->name = ef->ddbstrtab + es->st_name;
 940             symval->value = (caddr_t) ef->address + es->st_value;
 941             symval->size = es->st_size;
 942             return 0;
 943         }
 944         return ENOENT;
 945 }
 946
 947 static int
 948 link_elf_search_symbol(linker_file_t lf, caddr_t value,
 949                        c_linker_sym_t* sym, long* diffp)
 950 {
 951         elf_file_t ef = lf->priv;
 952         u_long off = (uintptr_t) (void *) value;
 953         u_long diff = off;
 954         u_long st_value;
 955         const Elf_Sym* es;
 956         const Elf_Sym* best = 0;
 957         int i;
 958
 959         for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
 960                 if (es->st_name == 0)
 961                         continue;
 962                 st_value = es->st_value + (uintptr_t) (void *) ef->address;
 963                 if (off >= st_value) {
 964                         if (off - st_value < diff) {
 965                                 diff = off - st_value;
 966                                 best = es;
 967                                 if (diff == 0)
 968                                         break;
 969                         } else if (off - st_value == diff) {
 970                                 best = es;
 971                         }
 972                 }
 973         }
 974         if (best == 0)
 975                 *diffp = off;
 976         else
 977                 *diffp = diff;
 978         *sym = (c_linker_sym_t) best;
 979
 980         return 0;
 981 }
 982
 983 /*
 984  * Look up a linker set on an ELF system.
 985  */
 986 static int
 987 link_elf_lookup_set(linker_file_t lf, const char *name,
 988                 void ***startp, void ***stopp, int *countp)
 989 {
 990         c_linker_sym_t sym;
 991         linker_symval_t symval;
 992         char *setsym;
 993         void **start, **stop;
 994         int len, error = 0, count;
 995
 996         len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
 997         setsym = kmalloc(len, M_LINKER, M_WAITOK);
 998
 999         /* get address of first entry */
1000         ksnprintf(setsym, len, "%s%s", "__start_set_", name);
1001         error = link_elf_lookup_symbol(lf, setsym, &sym);
1002         if (error)
1003                goto out;
1004         link_elf_symbol_values(lf, sym, &symval);
1005         if (symval.value == 0) {
1006                error = ESRCH;
1007                goto out;
1008         }
1009         start = (void **)symval.value;
1010
1011         /* get address of last entry */
1012         ksnprintf(setsym, len, "%s%s", "__stop_set_", name);
1013         error = link_elf_lookup_symbol(lf, setsym, &sym);
1014         if (error)
1015                goto out;
1016         link_elf_symbol_values(lf, sym, &symval);
1017         if (symval.value == 0) {
1018                error = ESRCH;
1019                goto out;
1020         }
1021         stop = (void **)symval.value;
1022
1023         /* and the number of entries */
1024         count = stop - start;
1025
1026         /* and copy out */
1027         if (startp)
1028                *startp = start;
1029         if (stopp)
1030                *stopp = stop;
1031         if (countp)
1032                *countp = count;
1033
1034         out:
1035         kfree(setsym, M_LINKER);
1036         return error;
1037 }
1038