The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/link_elf.c

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    1 /*-
    2  * Copyright (c) 1998-2000 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 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD: releng/8.3/sys/kern/link_elf.c 222880 2011-06-08 21:36:36Z dchagin $");
   29 
   30 #include "opt_ddb.h"
   31 #include "opt_gdb.h"
   32 
   33 #include <sys/param.h>
   34 #include <sys/systm.h>
   35 #ifdef GPROF
   36 #include <sys/gmon.h>
   37 #endif
   38 #include <sys/kernel.h>
   39 #include <sys/lock.h>
   40 #include <sys/malloc.h>
   41 #include <sys/mutex.h>
   42 #include <sys/mount.h>
   43 #include <sys/pcpu.h>
   44 #include <sys/proc.h>
   45 #include <sys/namei.h>
   46 #include <sys/fcntl.h>
   47 #include <sys/vnode.h>
   48 #include <sys/linker.h>
   49 
   50 #include <machine/elf.h>
   51 
   52 #include <net/vnet.h>
   53 
   54 #include <security/mac/mac_framework.h>
   55 
   56 #include <vm/vm.h>
   57 #include <vm/vm_param.h>
   58 #ifdef SPARSE_MAPPING
   59 #include <vm/vm_object.h>
   60 #include <vm/vm_kern.h>
   61 #include <vm/vm_extern.h>
   62 #endif
   63 #include <vm/pmap.h>
   64 #include <vm/vm_map.h>
   65 
   66 #include <sys/link_elf.h>
   67 
   68 #ifdef DDB_CTF
   69 #include <net/zlib.h>
   70 #endif
   71 
   72 #include "linker_if.h"
   73 
   74 #define MAXSEGS 4
   75 
   76 typedef struct elf_file {
   77         struct linker_file lf;          /* Common fields */
   78         int             preloaded;      /* Was file pre-loaded */
   79         caddr_t         address;        /* Relocation address */
   80 #ifdef SPARSE_MAPPING
   81         vm_object_t     object;         /* VM object to hold file pages */
   82 #endif
   83         Elf_Dyn         *dynamic;       /* Symbol table etc. */
   84         Elf_Hashelt     nbuckets;       /* DT_HASH info */
   85         Elf_Hashelt     nchains;
   86         const Elf_Hashelt *buckets;
   87         const Elf_Hashelt *chains;
   88         caddr_t         hash;
   89         caddr_t         strtab;         /* DT_STRTAB */
   90         int             strsz;          /* DT_STRSZ */
   91         const Elf_Sym   *symtab;                /* DT_SYMTAB */
   92         Elf_Addr        *got;           /* DT_PLTGOT */
   93         const Elf_Rel   *pltrel;        /* DT_JMPREL */
   94         int             pltrelsize;     /* DT_PLTRELSZ */
   95         const Elf_Rela  *pltrela;       /* DT_JMPREL */
   96         int             pltrelasize;    /* DT_PLTRELSZ */
   97         const Elf_Rel   *rel;           /* DT_REL */
   98         int             relsize;        /* DT_RELSZ */
   99         const Elf_Rela  *rela;          /* DT_RELA */
  100         int             relasize;       /* DT_RELASZ */
  101         caddr_t         modptr;
  102         const Elf_Sym   *ddbsymtab;     /* The symbol table we are using */
  103         long            ddbsymcnt;      /* Number of symbols */
  104         caddr_t         ddbstrtab;      /* String table */
  105         long            ddbstrcnt;      /* number of bytes in string table */
  106         caddr_t         symbase;        /* malloc'ed symbold base */
  107         caddr_t         strbase;        /* malloc'ed string base */
  108         caddr_t         ctftab;         /* CTF table */
  109         long            ctfcnt;         /* number of bytes in CTF table */
  110         caddr_t         ctfoff;         /* CTF offset table */
  111         caddr_t         typoff;         /* Type offset table */
  112         long            typlen;         /* Number of type entries. */
  113         Elf_Addr        pcpu_start;     /* Pre-relocation pcpu set start. */
  114         Elf_Addr        pcpu_stop;      /* Pre-relocation pcpu set stop. */
  115         Elf_Addr        pcpu_base;      /* Relocated pcpu set address. */
  116 #ifdef VIMAGE
  117         Elf_Addr        vnet_start;     /* Pre-relocation vnet set start. */
  118         Elf_Addr        vnet_stop;      /* Pre-relocation vnet set stop. */
  119         Elf_Addr        vnet_base;      /* Relocated vnet set address. */
  120 #endif
  121 #ifdef GDB
  122         struct link_map gdb;            /* hooks for gdb */
  123 #endif
  124 } *elf_file_t;
  125 
  126 #include <kern/kern_ctf.c>
  127 
  128 static int      link_elf_link_common_finish(linker_file_t);
  129 static int      link_elf_link_preload(linker_class_t cls,
  130                                       const char *, linker_file_t *);
  131 static int      link_elf_link_preload_finish(linker_file_t);
  132 static int      link_elf_load_file(linker_class_t, const char *,
  133                     linker_file_t *);
  134 static int      link_elf_lookup_symbol(linker_file_t, const char *,
  135                     c_linker_sym_t *);
  136 static int      link_elf_symbol_values(linker_file_t, c_linker_sym_t,
  137                     linker_symval_t *);
  138 static int      link_elf_search_symbol(linker_file_t, caddr_t,
  139                     c_linker_sym_t *, long *);
  140 
  141 static void     link_elf_unload_file(linker_file_t);
  142 static void     link_elf_unload_preload(linker_file_t);
  143 static int      link_elf_lookup_set(linker_file_t, const char *,
  144                     void ***, void ***, int *);
  145 static int      link_elf_each_function_name(linker_file_t,
  146                     int (*)(const char *, void *), void *);
  147 static int      link_elf_each_function_nameval(linker_file_t,
  148                     linker_function_nameval_callback_t, void *);
  149 static void     link_elf_reloc_local(linker_file_t);
  150 static long     link_elf_symtab_get(linker_file_t, const Elf_Sym **);
  151 static long     link_elf_strtab_get(linker_file_t, caddr_t *);
  152 static Elf_Addr elf_lookup(linker_file_t, Elf_Size, int);
  153 
  154 static kobj_method_t link_elf_methods[] = {
  155         KOBJMETHOD(linker_lookup_symbol,        link_elf_lookup_symbol),
  156         KOBJMETHOD(linker_symbol_values,        link_elf_symbol_values),
  157         KOBJMETHOD(linker_search_symbol,        link_elf_search_symbol),
  158         KOBJMETHOD(linker_unload,               link_elf_unload_file),
  159         KOBJMETHOD(linker_load_file,            link_elf_load_file),
  160         KOBJMETHOD(linker_link_preload,         link_elf_link_preload),
  161         KOBJMETHOD(linker_link_preload_finish,  link_elf_link_preload_finish),
  162         KOBJMETHOD(linker_lookup_set,           link_elf_lookup_set),
  163         KOBJMETHOD(linker_each_function_name,   link_elf_each_function_name),
  164         KOBJMETHOD(linker_each_function_nameval, link_elf_each_function_nameval),
  165         KOBJMETHOD(linker_ctf_get,              link_elf_ctf_get),
  166         KOBJMETHOD(linker_symtab_get,           link_elf_symtab_get),
  167         KOBJMETHOD(linker_strtab_get,           link_elf_strtab_get),
  168         { 0, 0 }
  169 };
  170 
  171 static struct linker_class link_elf_class = {
  172 #if ELF_TARG_CLASS == ELFCLASS32
  173         "elf32",
  174 #else
  175         "elf64",
  176 #endif
  177         link_elf_methods, sizeof(struct elf_file)
  178 };
  179 
  180 static int      parse_dynamic(elf_file_t);
  181 static int      relocate_file(elf_file_t);
  182 static int      link_elf_preload_parse_symbols(elf_file_t);
  183 
  184 #ifdef GDB
  185 static void     r_debug_state(struct r_debug *, struct link_map *);
  186 
  187 /*
  188  * A list of loaded modules for GDB to use for loading symbols.
  189  */
  190 struct r_debug r_debug;
  191 
  192 #define GDB_STATE(s) do {                               \
  193         r_debug.r_state = s; r_debug_state(NULL, NULL); \
  194 } while (0)
  195 
  196 /*
  197  * Function for the debugger to set a breakpoint on to gain control.
  198  */
  199 static void
  200 r_debug_state(struct r_debug *dummy_one __unused,
  201               struct link_map *dummy_two __unused)
  202 {
  203 }
  204 
  205 static void
  206 link_elf_add_gdb(struct link_map *l)
  207 {
  208         struct link_map *prev;
  209 
  210         l->l_next = NULL;
  211 
  212         if (r_debug.r_map == NULL) {
  213                 /* Add first. */
  214                 l->l_prev = NULL;
  215                 r_debug.r_map = l;
  216         } else {
  217                 /* Append to list. */
  218                 for (prev = r_debug.r_map;
  219                     prev->l_next != NULL;
  220                     prev = prev->l_next)
  221                         ;
  222                 l->l_prev = prev;
  223                 prev->l_next = l;
  224         }
  225 }
  226 
  227 static void
  228 link_elf_delete_gdb(struct link_map *l)
  229 {
  230         if (l->l_prev == NULL) {
  231                 /* Remove first. */
  232                 if ((r_debug.r_map = l->l_next) != NULL)
  233                         l->l_next->l_prev = NULL;
  234         } else {
  235                 /* Remove any but first. */
  236                 if ((l->l_prev->l_next = l->l_next) != NULL)
  237                         l->l_next->l_prev = l->l_prev;
  238         }
  239 }
  240 #endif /* GDB */
  241 
  242 #ifdef __ia64__
  243 Elf_Addr link_elf_get_gp(linker_file_t);
  244 #endif
  245 
  246 /*
  247  * The kernel symbol table starts here.
  248  */
  249 extern struct _dynamic _DYNAMIC;
  250 
  251 static void
  252 link_elf_error(const char *filename, const char *s)
  253 {
  254         if (filename == NULL)
  255                 printf("kldload: %s\n", s);
  256         else
  257                 printf("kldload: %s: %s\n", filename, s);
  258 }
  259 
  260 /*
  261  * Actions performed after linking/loading both the preloaded kernel and any
  262  * modules; whether preloaded or dynamicly loaded.
  263  */
  264 static int
  265 link_elf_link_common_finish(linker_file_t lf)
  266 {
  267 #ifdef GDB
  268         elf_file_t ef = (elf_file_t)lf;
  269         char *newfilename;
  270 #endif
  271         int error;
  272 
  273         /* Notify MD code that a module is being loaded. */
  274         error = elf_cpu_load_file(lf);
  275         if (error != 0)
  276                 return (error);
  277 
  278 #ifdef GDB
  279         GDB_STATE(RT_ADD);
  280         ef->gdb.l_addr = lf->address;
  281         newfilename = malloc(strlen(lf->filename) + 1, M_LINKER, M_WAITOK);
  282         strcpy(newfilename, lf->filename);
  283         ef->gdb.l_name = newfilename;
  284         ef->gdb.l_ld = ef->dynamic;
  285         link_elf_add_gdb(&ef->gdb);
  286         GDB_STATE(RT_CONSISTENT);
  287 #endif
  288 
  289         return (0);
  290 }
  291 
  292 static void
  293 link_elf_init(void* arg)
  294 {
  295         Elf_Dyn *dp;
  296         caddr_t modptr, baseptr, sizeptr;
  297         elf_file_t ef;
  298         char *modname;
  299 
  300         linker_add_class(&link_elf_class);
  301 
  302         dp = (Elf_Dyn *)&_DYNAMIC;
  303         modname = NULL;
  304         modptr = preload_search_by_type("elf" __XSTRING(__ELF_WORD_SIZE) " kernel");
  305         if (modptr == NULL)
  306                 modptr = preload_search_by_type("elf kernel");
  307         if (modptr != NULL)
  308                 modname = (char *)preload_search_info(modptr, MODINFO_NAME);
  309         if (modname == NULL)
  310                 modname = "kernel";
  311         linker_kernel_file = linker_make_file(modname, &link_elf_class);
  312         if (linker_kernel_file == NULL)
  313                 panic("%s: Can't create linker structures for kernel",
  314                     __func__);
  315 
  316         ef = (elf_file_t) linker_kernel_file;
  317         ef->preloaded = 1;
  318         ef->address = 0;
  319 #ifdef SPARSE_MAPPING
  320         ef->object = 0;
  321 #endif
  322         ef->dynamic = dp;
  323 
  324         if (dp != NULL)
  325                 parse_dynamic(ef);
  326         linker_kernel_file->address = (caddr_t) KERNBASE;
  327         linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;
  328 
  329         if (modptr != NULL) {
  330                 ef->modptr = modptr;
  331                 baseptr = preload_search_info(modptr, MODINFO_ADDR);
  332                 if (baseptr != NULL)
  333                         linker_kernel_file->address = *(caddr_t *)baseptr;
  334                 sizeptr = preload_search_info(modptr, MODINFO_SIZE);
  335                 if (sizeptr != NULL)
  336                         linker_kernel_file->size = *(size_t *)sizeptr;
  337         }
  338         (void)link_elf_preload_parse_symbols(ef);
  339 
  340 #ifdef GDB
  341         r_debug.r_map = NULL;
  342         r_debug.r_brk = r_debug_state;
  343         r_debug.r_state = RT_CONSISTENT;
  344 #endif
  345 
  346         (void)link_elf_link_common_finish(linker_kernel_file);
  347         linker_kernel_file->flags |= LINKER_FILE_LINKED;
  348 }
  349 
  350 SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_THIRD, link_elf_init, 0);
  351 
  352 static int
  353 link_elf_preload_parse_symbols(elf_file_t ef)
  354 {
  355         caddr_t pointer;
  356         caddr_t ssym, esym, base;
  357         caddr_t strtab;
  358         int strcnt;
  359         Elf_Sym *symtab;
  360         int symcnt;
  361 
  362         if (ef->modptr == NULL)
  363                 return (0);
  364         pointer = preload_search_info(ef->modptr,
  365             MODINFO_METADATA | MODINFOMD_SSYM);
  366         if (pointer == NULL)
  367                 return (0);
  368         ssym = *(caddr_t *)pointer;
  369         pointer = preload_search_info(ef->modptr,
  370             MODINFO_METADATA | MODINFOMD_ESYM);
  371         if (pointer == NULL)
  372                 return (0);
  373         esym = *(caddr_t *)pointer;
  374 
  375         base = ssym;
  376 
  377         symcnt = *(long *)base;
  378         base += sizeof(long);
  379         symtab = (Elf_Sym *)base;
  380         base += roundup(symcnt, sizeof(long));
  381 
  382         if (base > esym || base < ssym) {
  383                 printf("Symbols are corrupt!\n");
  384                 return (EINVAL);
  385         }
  386 
  387         strcnt = *(long *)base;
  388         base += sizeof(long);
  389         strtab = base;
  390         base += roundup(strcnt, sizeof(long));
  391 
  392         if (base > esym || base < ssym) {
  393                 printf("Symbols are corrupt!\n");
  394                 return (EINVAL);
  395         }
  396 
  397         ef->ddbsymtab = symtab;
  398         ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
  399         ef->ddbstrtab = strtab;
  400         ef->ddbstrcnt = strcnt;
  401 
  402         return (0);
  403 }
  404 
  405 static int
  406 parse_dynamic(elf_file_t ef)
  407 {
  408         Elf_Dyn *dp;
  409         int plttype = DT_REL;
  410 
  411         for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
  412                 switch (dp->d_tag) {
  413                 case DT_HASH:
  414                 {
  415                         /* From src/libexec/rtld-elf/rtld.c */
  416                         const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
  417                             (ef->address + dp->d_un.d_ptr);
  418                         ef->nbuckets = hashtab[0];
  419                         ef->nchains = hashtab[1];
  420                         ef->buckets = hashtab + 2;
  421                         ef->chains = ef->buckets + ef->nbuckets;
  422                         break;
  423                 }
  424                 case DT_STRTAB:
  425                         ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr);
  426                         break;
  427                 case DT_STRSZ:
  428                         ef->strsz = dp->d_un.d_val;
  429                         break;
  430                 case DT_SYMTAB:
  431                         ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr);
  432                         break;
  433                 case DT_SYMENT:
  434                         if (dp->d_un.d_val != sizeof(Elf_Sym))
  435                                 return (ENOEXEC);
  436                         break;
  437                 case DT_PLTGOT:
  438                         ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr);
  439                         break;
  440                 case DT_REL:
  441                         ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
  442                         break;
  443                 case DT_RELSZ:
  444                         ef->relsize = dp->d_un.d_val;
  445                         break;
  446                 case DT_RELENT:
  447                         if (dp->d_un.d_val != sizeof(Elf_Rel))
  448                                 return (ENOEXEC);
  449                         break;
  450                 case DT_JMPREL:
  451                         ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
  452                         break;
  453                 case DT_PLTRELSZ:
  454                         ef->pltrelsize = dp->d_un.d_val;
  455                         break;
  456                 case DT_RELA:
  457                         ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr);
  458                         break;
  459                 case DT_RELASZ:
  460                         ef->relasize = dp->d_un.d_val;
  461                         break;
  462                 case DT_RELAENT:
  463                         if (dp->d_un.d_val != sizeof(Elf_Rela))
  464                                 return (ENOEXEC);
  465                         break;
  466                 case DT_PLTREL:
  467                         plttype = dp->d_un.d_val;
  468                         if (plttype != DT_REL && plttype != DT_RELA)
  469                                 return (ENOEXEC);
  470                         break;
  471 #ifdef GDB
  472                 case DT_DEBUG:
  473                         dp->d_un.d_ptr = (Elf_Addr)&r_debug;
  474                         break;
  475 #endif
  476                 }
  477         }
  478 
  479         if (plttype == DT_RELA) {
  480                 ef->pltrela = (const Elf_Rela *)ef->pltrel;
  481                 ef->pltrel = NULL;
  482                 ef->pltrelasize = ef->pltrelsize;
  483                 ef->pltrelsize = 0;
  484         }
  485 
  486         ef->ddbsymtab = ef->symtab;
  487         ef->ddbsymcnt = ef->nchains;
  488         ef->ddbstrtab = ef->strtab;
  489         ef->ddbstrcnt = ef->strsz;
  490 
  491         return (0);
  492 }
  493 
  494 static int
  495 parse_dpcpu(elf_file_t ef)
  496 { 
  497         int count;
  498         int error;
  499 
  500         ef->pcpu_start = 0;
  501         ef->pcpu_stop = 0;
  502         error = link_elf_lookup_set(&ef->lf, "pcpu", (void ***)&ef->pcpu_start,
  503             (void ***)&ef->pcpu_stop, &count);
  504         /* Error just means there is no pcpu set to relocate. */
  505         if (error != 0)
  506                 return (0);
  507         count *= sizeof(void *);
  508         /*
  509          * Allocate space in the primary pcpu area.  Copy in our
  510          * initialization from the data section and then initialize
  511          * all per-cpu storage from that.
  512          */
  513         ef->pcpu_base = (Elf_Addr)(uintptr_t)dpcpu_alloc(count);
  514         if (ef->pcpu_base == 0)
  515                 return (ENOSPC);
  516         memcpy((void *)ef->pcpu_base, (void *)ef->pcpu_start, count);
  517         dpcpu_copy((void *)ef->pcpu_base, count);
  518 
  519         return (0);
  520 }
  521 
  522 #ifdef VIMAGE
  523 static int
  524 parse_vnet(elf_file_t ef)
  525 { 
  526         int count;
  527         int error;
  528 
  529         ef->vnet_start = 0;
  530         ef->vnet_stop = 0;
  531         error = link_elf_lookup_set(&ef->lf, "vnet", (void ***)&ef->vnet_start,
  532             (void ***)&ef->vnet_stop, &count);
  533         /* Error just means there is no vnet data set to relocate. */
  534         if (error != 0)
  535                 return (0);
  536         count *= sizeof(void *);
  537         /*
  538          * Allocate space in the primary vnet area.  Copy in our
  539          * initialization from the data section and then initialize
  540          * all per-vnet storage from that.
  541          */
  542         ef->vnet_base = (Elf_Addr)(uintptr_t)vnet_data_alloc(count);
  543         if (ef->vnet_base == 0)
  544                 return (ENOSPC);
  545         memcpy((void *)ef->vnet_base, (void *)ef->vnet_start, count);
  546         vnet_data_copy((void *)ef->vnet_base, count);
  547 
  548         return (0);
  549 }
  550 #endif
  551 
  552 static int
  553 link_elf_link_preload(linker_class_t cls,
  554     const char* filename, linker_file_t *result)
  555 {
  556         caddr_t modptr, baseptr, sizeptr, dynptr;
  557         char *type;
  558         elf_file_t ef;
  559         linker_file_t lf;
  560         int error;
  561         vm_offset_t dp;
  562 
  563         /* Look to see if we have the file preloaded */
  564         modptr = preload_search_by_name(filename);
  565         if (modptr == NULL)
  566                 return (ENOENT);
  567 
  568         type = (char *)preload_search_info(modptr, MODINFO_TYPE);
  569         baseptr = preload_search_info(modptr, MODINFO_ADDR);
  570         sizeptr = preload_search_info(modptr, MODINFO_SIZE);
  571         dynptr = preload_search_info(modptr,
  572             MODINFO_METADATA | MODINFOMD_DYNAMIC);
  573         if (type == NULL ||
  574             (strcmp(type, "elf" __XSTRING(__ELF_WORD_SIZE) " module") != 0 &&
  575              strcmp(type, "elf module") != 0))
  576                 return (EFTYPE);
  577         if (baseptr == NULL || sizeptr == NULL || dynptr == NULL)
  578                 return (EINVAL);
  579 
  580         lf = linker_make_file(filename, &link_elf_class);
  581         if (lf == NULL)
  582                 return (ENOMEM);
  583 
  584         ef = (elf_file_t) lf;
  585         ef->preloaded = 1;
  586         ef->modptr = modptr;
  587         ef->address = *(caddr_t *)baseptr;
  588 #ifdef SPARSE_MAPPING
  589         ef->object = 0;
  590 #endif
  591         dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
  592         ef->dynamic = (Elf_Dyn *)dp;
  593         lf->address = ef->address;
  594         lf->size = *(size_t *)sizeptr;
  595 
  596         error = parse_dynamic(ef);
  597         if (error == 0)
  598                 error = parse_dpcpu(ef);
  599 #ifdef VIMAGE
  600         if (error == 0)
  601                 error = parse_vnet(ef);
  602 #endif
  603         if (error != 0) {
  604                 linker_file_unload(lf, LINKER_UNLOAD_FORCE);
  605                 return (error);
  606         }
  607         link_elf_reloc_local(lf);
  608         *result = lf;
  609         return (0);
  610 }
  611 
  612 static int
  613 link_elf_link_preload_finish(linker_file_t lf)
  614 {
  615         elf_file_t ef;
  616         int error;
  617 
  618         ef = (elf_file_t) lf;
  619 #if 0   /* this will be more trouble than it's worth for now */
  620         for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
  621                 if (dp->d_tag != DT_NEEDED)
  622                         continue;
  623                 modname = ef->strtab + dp->d_un.d_val;
  624                 error = linker_load_module(modname, lf);
  625                 if (error != 0)
  626                         goto out;
  627     }
  628 #endif
  629         error = relocate_file(ef);
  630         if (error != 0)
  631                 return (error);
  632         (void)link_elf_preload_parse_symbols(ef);
  633 
  634         return (link_elf_link_common_finish(lf));
  635 }
  636 
  637 static int
  638 link_elf_load_file(linker_class_t cls, const char* filename,
  639     linker_file_t* result)
  640 {
  641         struct nameidata nd;
  642         struct thread* td = curthread;  /* XXX */
  643         Elf_Ehdr *hdr;
  644         caddr_t firstpage;
  645         int nbytes, i;
  646         Elf_Phdr *phdr;
  647         Elf_Phdr *phlimit;
  648         Elf_Phdr *segs[MAXSEGS];
  649         int nsegs;
  650         Elf_Phdr *phdyn;
  651         Elf_Phdr *phphdr;
  652         caddr_t mapbase;
  653         size_t mapsize;
  654         Elf_Off base_offset;
  655         Elf_Addr base_vaddr;
  656         Elf_Addr base_vlimit;
  657         int error = 0;
  658         int resid, flags;
  659         elf_file_t ef;
  660         linker_file_t lf;
  661         Elf_Shdr *shdr;
  662         int symtabindex;
  663         int symstrindex;
  664         int symcnt;
  665         int strcnt;
  666         int vfslocked;
  667 
  668         shdr = NULL;
  669         lf = NULL;
  670 
  671         NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, filename, td);
  672         flags = FREAD;
  673         error = vn_open(&nd, &flags, 0, NULL);
  674         if (error != 0)
  675                 return (error);
  676         vfslocked = NDHASGIANT(&nd);
  677         NDFREE(&nd, NDF_ONLY_PNBUF);
  678         if (nd.ni_vp->v_type != VREG) {
  679                 error = ENOEXEC;
  680                 firstpage = NULL;
  681                 goto out;
  682         }
  683 #ifdef MAC
  684         error = mac_kld_check_load(curthread->td_ucred, nd.ni_vp);
  685         if (error != 0) {
  686                 firstpage = NULL;
  687                 goto out;
  688         }
  689 #endif
  690 
  691         /*
  692          * Read the elf header from the file.
  693          */
  694         firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK);
  695         hdr = (Elf_Ehdr *)firstpage;
  696         error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0,
  697             UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
  698             &resid, td);
  699         nbytes = PAGE_SIZE - resid;
  700         if (error != 0)
  701                 goto out;
  702 
  703         if (!IS_ELF(*hdr)) {
  704                 error = ENOEXEC;
  705                 goto out;
  706         }
  707 
  708         if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
  709             hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
  710                 link_elf_error(filename, "Unsupported file layout");
  711                 error = ENOEXEC;
  712                 goto out;
  713         }
  714         if (hdr->e_ident[EI_VERSION] != EV_CURRENT ||
  715             hdr->e_version != EV_CURRENT) {
  716                 link_elf_error(filename, "Unsupported file version");
  717                 error = ENOEXEC;
  718                 goto out;
  719         }
  720         if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
  721                 error = ENOSYS;
  722                 goto out;
  723         }
  724         if (hdr->e_machine != ELF_TARG_MACH) {
  725                 link_elf_error(filename, "Unsupported machine");
  726                 error = ENOEXEC;
  727                 goto out;
  728         }
  729 
  730         /*
  731          * We rely on the program header being in the first page.
  732          * This is not strictly required by the ABI specification, but
  733          * it seems to always true in practice.  And, it simplifies
  734          * things considerably.
  735          */
  736         if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
  737               (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
  738               (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
  739                 link_elf_error(filename, "Unreadable program headers");
  740 
  741         /*
  742          * Scan the program header entries, and save key information.
  743          *
  744          * We rely on there being exactly two load segments, text and data,
  745          * in that order.
  746          */
  747         phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
  748         phlimit = phdr + hdr->e_phnum;
  749         nsegs = 0;
  750         phdyn = NULL;
  751         phphdr = NULL;
  752         while (phdr < phlimit) {
  753                 switch (phdr->p_type) {
  754                 case PT_LOAD:
  755                         if (nsegs == MAXSEGS) {
  756                                 link_elf_error(filename, "Too many sections");
  757                                 error = ENOEXEC;
  758                                 goto out;
  759                         }
  760                         /*
  761                          * XXX: We just trust they come in right order ??
  762                          */
  763                         segs[nsegs] = phdr;
  764                         ++nsegs;
  765                         break;
  766 
  767                 case PT_PHDR:
  768                         phphdr = phdr;
  769                         break;
  770 
  771                 case PT_DYNAMIC:
  772                         phdyn = phdr;
  773                         break;
  774 
  775                 case PT_INTERP:
  776                         error = ENOSYS;
  777                         goto out;
  778                 }
  779 
  780                 ++phdr;
  781         }
  782         if (phdyn == NULL) {
  783                 link_elf_error(filename, "Object is not dynamically-linked");
  784                 error = ENOEXEC;
  785                 goto out;
  786         }
  787         if (nsegs == 0) {
  788                 link_elf_error(filename, "No sections");
  789                 error = ENOEXEC;
  790                 goto out;
  791         }
  792 
  793         /*
  794          * Allocate the entire address space of the object, to stake
  795          * out our contiguous region, and to establish the base
  796          * address for relocation.
  797          */
  798         base_offset = trunc_page(segs[0]->p_offset);
  799         base_vaddr = trunc_page(segs[0]->p_vaddr);
  800         base_vlimit = round_page(segs[nsegs - 1]->p_vaddr + 
  801             segs[nsegs - 1]->p_memsz);
  802         mapsize = base_vlimit - base_vaddr;
  803 
  804         lf = linker_make_file(filename, &link_elf_class);
  805         if (lf == NULL) {
  806                 error = ENOMEM;
  807                 goto out;
  808         }
  809 
  810         ef = (elf_file_t) lf;
  811 #ifdef SPARSE_MAPPING
  812         ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
  813         if (ef->object == NULL) {
  814                 error = ENOMEM;
  815                 goto out;
  816         }
  817         ef->address = (caddr_t) vm_map_min(kernel_map);
  818         error = vm_map_find(kernel_map, ef->object, 0,
  819             (vm_offset_t *) &ef->address, mapsize, 1,
  820             VM_PROT_ALL, VM_PROT_ALL, 0);
  821         if (error != 0) {
  822                 vm_object_deallocate(ef->object);
  823                 ef->object = 0;
  824                 goto out;
  825         }
  826 #else
  827         ef->address = malloc(mapsize, M_LINKER, M_WAITOK);
  828 #endif
  829         mapbase = ef->address;
  830 
  831         /*
  832          * Read the text and data sections and zero the bss.
  833          */
  834         for (i = 0; i < nsegs; i++) {
  835                 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
  836                 error = vn_rdwr(UIO_READ, nd.ni_vp,
  837                     segbase, segs[i]->p_filesz, segs[i]->p_offset,
  838                     UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
  839                     &resid, td);
  840                 if (error != 0)
  841                         goto out;
  842                 bzero(segbase + segs[i]->p_filesz,
  843                     segs[i]->p_memsz - segs[i]->p_filesz);
  844 
  845 #ifdef SPARSE_MAPPING
  846                 /*
  847                  * Wire down the pages
  848                  */
  849                 error = vm_map_wire(kernel_map,
  850                     (vm_offset_t) segbase,
  851                     (vm_offset_t) segbase + segs[i]->p_memsz,
  852                     VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
  853                 if (error != KERN_SUCCESS) {
  854                         error = ENOMEM;
  855                         goto out;
  856                 }
  857 #endif
  858         }
  859 
  860 #ifdef GPROF
  861         /* Update profiling information with the new text segment. */
  862         mtx_lock(&Giant);
  863         kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr +
  864             segs[0]->p_memsz));
  865         mtx_unlock(&Giant);
  866 #endif
  867 
  868         ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
  869 
  870         lf->address = ef->address;
  871         lf->size = mapsize;
  872 
  873         error = parse_dynamic(ef);
  874         if (error != 0)
  875                 goto out;
  876         error = parse_dpcpu(ef);
  877         if (error != 0)
  878                 goto out;
  879 #ifdef VIMAGE
  880         error = parse_vnet(ef);
  881         if (error != 0)
  882                 goto out;
  883 #endif
  884         link_elf_reloc_local(lf);
  885 
  886         VOP_UNLOCK(nd.ni_vp, 0);
  887         error = linker_load_dependencies(lf);
  888         vn_lock(nd.ni_vp, LK_EXCLUSIVE | LK_RETRY);
  889         if (error != 0)
  890                 goto out;
  891 #if 0   /* this will be more trouble than it's worth for now */
  892         for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
  893                 if (dp->d_tag != DT_NEEDED)
  894                         continue;
  895                 modname = ef->strtab + dp->d_un.d_val;
  896                 error = linker_load_module(modname, lf);
  897                 if (error != 0)
  898                         goto out;
  899     }
  900 #endif
  901         error = relocate_file(ef);
  902         if (error != 0)
  903                 goto out;
  904 
  905         /*
  906          * Try and load the symbol table if it's present.  (you can
  907          * strip it!)
  908          */
  909         nbytes = hdr->e_shnum * hdr->e_shentsize;
  910         if (nbytes == 0 || hdr->e_shoff == 0)
  911                 goto nosyms;
  912         shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
  913         error = vn_rdwr(UIO_READ, nd.ni_vp,
  914             (caddr_t)shdr, nbytes, hdr->e_shoff,
  915             UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
  916             &resid, td);
  917         if (error != 0)
  918                 goto out;
  919         symtabindex = -1;
  920         symstrindex = -1;
  921         for (i = 0; i < hdr->e_shnum; i++) {
  922                 if (shdr[i].sh_type == SHT_SYMTAB) {
  923                         symtabindex = i;
  924                         symstrindex = shdr[i].sh_link;
  925                 }
  926         }
  927         if (symtabindex < 0 || symstrindex < 0)
  928                 goto nosyms;
  929 
  930         symcnt = shdr[symtabindex].sh_size;
  931         ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK);
  932         strcnt = shdr[symstrindex].sh_size;
  933         ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK);
  934 
  935         error = vn_rdwr(UIO_READ, nd.ni_vp,
  936             ef->symbase, symcnt, shdr[symtabindex].sh_offset,
  937             UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
  938             &resid, td);
  939         if (error != 0)
  940                 goto out;
  941         error = vn_rdwr(UIO_READ, nd.ni_vp,
  942             ef->strbase, strcnt, shdr[symstrindex].sh_offset,
  943             UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
  944             &resid, td);
  945         if (error != 0)
  946                 goto out;
  947 
  948         ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
  949         ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
  950         ef->ddbstrcnt = strcnt;
  951         ef->ddbstrtab = ef->strbase;
  952 
  953         error = link_elf_link_common_finish(lf);
  954         if (error != 0)
  955                 goto out;
  956 
  957 nosyms:
  958         *result = lf;
  959 
  960 out:
  961         VOP_UNLOCK(nd.ni_vp, 0);
  962         vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
  963         VFS_UNLOCK_GIANT(vfslocked);
  964         if (error != 0 && lf != NULL)
  965                 linker_file_unload(lf, LINKER_UNLOAD_FORCE);
  966         if (shdr != NULL)
  967                 free(shdr, M_LINKER);
  968         if (firstpage != NULL)
  969                 free(firstpage, M_LINKER);
  970 
  971         return (error);
  972 }
  973 
  974 Elf_Addr
  975 elf_relocaddr(linker_file_t lf, Elf_Addr x)
  976 {
  977         elf_file_t ef;
  978 
  979         ef = (elf_file_t)lf;
  980         if (x >= ef->pcpu_start && x < ef->pcpu_stop)
  981                 return ((x - ef->pcpu_start) + ef->pcpu_base);
  982 #ifdef VIMAGE
  983         if (x >= ef->vnet_start && x < ef->vnet_stop)
  984                 return ((x - ef->vnet_start) + ef->vnet_base);
  985 #endif
  986         return (x);
  987 }
  988 
  989 
  990 static void
  991 link_elf_unload_file(linker_file_t file)
  992 {
  993         elf_file_t ef = (elf_file_t) file;
  994 
  995         if (ef->pcpu_base != 0) {
  996                 dpcpu_free((void *)ef->pcpu_base,
  997                     ef->pcpu_stop - ef->pcpu_start);
  998         }
  999 #ifdef VIMAGE
 1000         if (ef->vnet_base != 0) {
 1001                 vnet_data_free((void *)ef->vnet_base,
 1002                     ef->vnet_stop - ef->vnet_start);
 1003         }
 1004 #endif
 1005 #ifdef GDB
 1006         if (ef->gdb.l_ld != NULL) {
 1007                 GDB_STATE(RT_DELETE);
 1008                 free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER);
 1009                 link_elf_delete_gdb(&ef->gdb);
 1010                 GDB_STATE(RT_CONSISTENT);
 1011         }
 1012 #endif
 1013 
 1014         /* Notify MD code that a module is being unloaded. */
 1015         elf_cpu_unload_file(file);
 1016 
 1017         if (ef->preloaded) {
 1018                 link_elf_unload_preload(file);
 1019                 return;
 1020         }
 1021 
 1022 #ifdef SPARSE_MAPPING
 1023         if (ef->object != NULL) {
 1024                 vm_map_remove(kernel_map, (vm_offset_t) ef->address,
 1025                     (vm_offset_t) ef->address
 1026                     + (ef->object->size << PAGE_SHIFT));
 1027         }
 1028 #else
 1029         if (ef->address != NULL)
 1030                 free(ef->address, M_LINKER);
 1031 #endif
 1032         if (ef->symbase != NULL)
 1033                 free(ef->symbase, M_LINKER);
 1034         if (ef->strbase != NULL)
 1035                 free(ef->strbase, M_LINKER);
 1036         if (ef->ctftab != NULL)
 1037                 free(ef->ctftab, M_LINKER);
 1038         if (ef->ctfoff != NULL)
 1039                 free(ef->ctfoff, M_LINKER);
 1040         if (ef->typoff != NULL)
 1041                 free(ef->typoff, M_LINKER);
 1042 }
 1043 
 1044 static void
 1045 link_elf_unload_preload(linker_file_t file)
 1046 {
 1047         if (file->filename != NULL)
 1048                 preload_delete_name(file->filename);
 1049 }
 1050 
 1051 static const char *
 1052 symbol_name(elf_file_t ef, Elf_Size r_info)
 1053 {
 1054         const Elf_Sym *ref;
 1055 
 1056         if (ELF_R_SYM(r_info)) {
 1057                 ref = ef->symtab + ELF_R_SYM(r_info);
 1058                 return (ef->strtab + ref->st_name);
 1059         }
 1060         return (NULL);
 1061 }
 1062 
 1063 static int
 1064 relocate_file(elf_file_t ef)
 1065 {
 1066         const Elf_Rel *rellim;
 1067         const Elf_Rel *rel;
 1068         const Elf_Rela *relalim;
 1069         const Elf_Rela *rela;
 1070         const char *symname;
 1071 
 1072         /* Perform relocations without addend if there are any: */
 1073         rel = ef->rel;
 1074         if (rel != NULL) {
 1075                 rellim = (const Elf_Rel *)
 1076                     ((const char *)ef->rel + ef->relsize);
 1077                 while (rel < rellim) {
 1078                         if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel,
 1079                             ELF_RELOC_REL, elf_lookup)) {
 1080                                 symname = symbol_name(ef, rel->r_info);
 1081                                 printf("link_elf: symbol %s undefined\n", symname);
 1082                                 return (ENOENT);
 1083                         }
 1084                         rel++;
 1085                 }
 1086         }
 1087 
 1088         /* Perform relocations with addend if there are any: */
 1089         rela = ef->rela;
 1090         if (rela != NULL) {
 1091                 relalim = (const Elf_Rela *)
 1092                     ((const char *)ef->rela + ef->relasize);
 1093                 while (rela < relalim) {
 1094                         if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela,
 1095                             ELF_RELOC_RELA, elf_lookup)) {
 1096                                 symname = symbol_name(ef, rela->r_info);
 1097                                 printf("link_elf: symbol %s undefined\n",
 1098                                     symname);
 1099                                 return (ENOENT);
 1100                         }
 1101                         rela++;
 1102                 }
 1103         }
 1104 
 1105         /* Perform PLT relocations without addend if there are any: */
 1106         rel = ef->pltrel;
 1107         if (rel != NULL) {
 1108                 rellim = (const Elf_Rel *)
 1109                     ((const char *)ef->pltrel + ef->pltrelsize);
 1110                 while (rel < rellim) {
 1111                         if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel,
 1112                             ELF_RELOC_REL, elf_lookup)) {
 1113                                 symname = symbol_name(ef, rel->r_info);
 1114                                 printf("link_elf: symbol %s undefined\n",
 1115                                     symname);
 1116                                 return (ENOENT);
 1117                         }
 1118                         rel++;
 1119                 }
 1120         }
 1121 
 1122         /* Perform relocations with addend if there are any: */
 1123         rela = ef->pltrela;
 1124         if (rela != NULL) {
 1125                 relalim = (const Elf_Rela *)
 1126                     ((const char *)ef->pltrela + ef->pltrelasize);
 1127                 while (rela < relalim) {
 1128                         if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela,
 1129                             ELF_RELOC_RELA, elf_lookup)) {
 1130                                 symname = symbol_name(ef, rela->r_info);
 1131                                 printf("link_elf: symbol %s undefined\n",
 1132                                     symname);
 1133                                 return (ENOENT);
 1134                         }
 1135                         rela++;
 1136                 }
 1137         }
 1138 
 1139         return (0);
 1140 }
 1141 
 1142 /*
 1143  * Hash function for symbol table lookup.  Don't even think about changing
 1144  * this.  It is specified by the System V ABI.
 1145  */
 1146 static unsigned long
 1147 elf_hash(const char *name)
 1148 {
 1149         const unsigned char *p = (const unsigned char *) name;
 1150         unsigned long h = 0;
 1151         unsigned long g;
 1152 
 1153         while (*p != '\0') {
 1154                 h = (h << 4) + *p++;
 1155                 if ((g = h & 0xf0000000) != 0)
 1156                         h ^= g >> 24;
 1157                 h &= ~g;
 1158         }
 1159         return (h);
 1160 }
 1161 
 1162 static int
 1163 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym)
 1164 {
 1165         elf_file_t ef = (elf_file_t) lf;
 1166         unsigned long symnum;
 1167         const Elf_Sym* symp;
 1168         const char *strp;
 1169         unsigned long hash;
 1170         int i;
 1171 
 1172         /* If we don't have a hash, bail. */
 1173         if (ef->buckets == NULL || ef->nbuckets == 0) {
 1174                 printf("link_elf_lookup_symbol: missing symbol hash table\n");
 1175                 return (ENOENT);
 1176         }
 1177 
 1178         /* First, search hashed global symbols */
 1179         hash = elf_hash(name);
 1180         symnum = ef->buckets[hash % ef->nbuckets];
 1181 
 1182         while (symnum != STN_UNDEF) {
 1183                 if (symnum >= ef->nchains) {
 1184                         printf("%s: corrupt symbol table\n", __func__);
 1185                         return (ENOENT);
 1186                 }
 1187 
 1188                 symp = ef->symtab + symnum;
 1189                 if (symp->st_name == 0) {
 1190                         printf("%s: corrupt symbol table\n", __func__);
 1191                         return (ENOENT);
 1192                 }
 1193 
 1194                 strp = ef->strtab + symp->st_name;
 1195 
 1196                 if (strcmp(name, strp) == 0) {
 1197                         if (symp->st_shndx != SHN_UNDEF ||
 1198                             (symp->st_value != 0 &&
 1199                              ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
 1200                                 *sym = (c_linker_sym_t) symp;
 1201                                 return (0);
 1202                         }
 1203                         return (ENOENT);
 1204                 }
 1205 
 1206                 symnum = ef->chains[symnum];
 1207         }
 1208 
 1209         /* If we have not found it, look at the full table (if loaded) */
 1210         if (ef->symtab == ef->ddbsymtab)
 1211                 return (ENOENT);
 1212 
 1213         /* Exhaustive search */
 1214         for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
 1215                 strp = ef->ddbstrtab + symp->st_name;
 1216                 if (strcmp(name, strp) == 0) {
 1217                         if (symp->st_shndx != SHN_UNDEF ||
 1218                             (symp->st_value != 0 &&
 1219                              ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
 1220                                 *sym = (c_linker_sym_t) symp;
 1221                                 return (0);
 1222                         }
 1223                         return (ENOENT);
 1224                 }
 1225         }
 1226 
 1227         return (ENOENT);
 1228 }
 1229 
 1230 static int
 1231 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym,
 1232     linker_symval_t *symval)
 1233 {
 1234         elf_file_t ef = (elf_file_t) lf;
 1235         const Elf_Sym* es = (const Elf_Sym*) sym;
 1236 
 1237         if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) {
 1238                 symval->name = ef->strtab + es->st_name;
 1239                 symval->value = (caddr_t) ef->address + es->st_value;
 1240                 symval->size = es->st_size;
 1241                 return (0);
 1242         }
 1243         if (ef->symtab == ef->ddbsymtab)
 1244                 return (ENOENT);
 1245         if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
 1246                 symval->name = ef->ddbstrtab + es->st_name;
 1247                 symval->value = (caddr_t) ef->address + es->st_value;
 1248                 symval->size = es->st_size;
 1249                 return (0);
 1250         }
 1251         return (ENOENT);
 1252 }
 1253 
 1254 static int
 1255 link_elf_search_symbol(linker_file_t lf, caddr_t value,
 1256     c_linker_sym_t *sym, long *diffp)
 1257 {
 1258         elf_file_t ef = (elf_file_t) lf;
 1259         u_long off = (uintptr_t) (void *) value;
 1260         u_long diff = off;
 1261         u_long st_value;
 1262         const Elf_Sym* es;
 1263         const Elf_Sym* best = 0;
 1264         int i;
 1265 
 1266         for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
 1267                 if (es->st_name == 0)
 1268                         continue;
 1269                 st_value = es->st_value + (uintptr_t) (void *) ef->address;
 1270                 if (off >= st_value) {
 1271                         if (off - st_value < diff) {
 1272                                 diff = off - st_value;
 1273                                 best = es;
 1274                                 if (diff == 0)
 1275                                         break;
 1276                         } else if (off - st_value == diff) {
 1277                                 best = es;
 1278                         }
 1279                 }
 1280         }
 1281         if (best == 0)
 1282                 *diffp = off;
 1283         else
 1284                 *diffp = diff;
 1285         *sym = (c_linker_sym_t) best;
 1286 
 1287         return (0);
 1288 }
 1289 
 1290 /*
 1291  * Look up a linker set on an ELF system.
 1292  */
 1293 static int
 1294 link_elf_lookup_set(linker_file_t lf, const char *name,
 1295     void ***startp, void ***stopp, int *countp)
 1296 {
 1297         c_linker_sym_t sym;
 1298         linker_symval_t symval;
 1299         char *setsym;
 1300         void **start, **stop;
 1301         int len, error = 0, count;
 1302 
 1303         len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
 1304         setsym = malloc(len, M_LINKER, M_WAITOK);
 1305 
 1306         /* get address of first entry */
 1307         snprintf(setsym, len, "%s%s", "__start_set_", name);
 1308         error = link_elf_lookup_symbol(lf, setsym, &sym);
 1309         if (error != 0)
 1310                 goto out;
 1311         link_elf_symbol_values(lf, sym, &symval);
 1312         if (symval.value == 0) {
 1313                 error = ESRCH;
 1314                 goto out;
 1315         }
 1316         start = (void **)symval.value;
 1317 
 1318         /* get address of last entry */
 1319         snprintf(setsym, len, "%s%s", "__stop_set_", name);
 1320         error = link_elf_lookup_symbol(lf, setsym, &sym);
 1321         if (error != 0)
 1322                 goto out;
 1323         link_elf_symbol_values(lf, sym, &symval);
 1324         if (symval.value == 0) {
 1325                 error = ESRCH;
 1326                 goto out;
 1327         }
 1328         stop = (void **)symval.value;
 1329 
 1330         /* and the number of entries */
 1331         count = stop - start;
 1332 
 1333         /* and copy out */
 1334         if (startp != NULL)
 1335                 *startp = start;
 1336         if (stopp != NULL)
 1337                 *stopp = stop;
 1338         if (countp != NULL)
 1339                 *countp = count;
 1340 
 1341 out:
 1342         free(setsym, M_LINKER);
 1343         return (error);
 1344 }
 1345 
 1346 static int
 1347 link_elf_each_function_name(linker_file_t file,
 1348   int (*callback)(const char *, void *), void *opaque)
 1349 {
 1350         elf_file_t ef = (elf_file_t)file;
 1351         const Elf_Sym *symp;
 1352         int i, error;
 1353         
 1354         /* Exhaustive search */
 1355         for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
 1356                 if (symp->st_value != 0 &&
 1357                     ELF_ST_TYPE(symp->st_info) == STT_FUNC) {
 1358                         error = callback(ef->ddbstrtab + symp->st_name, opaque);
 1359                         if (error != 0)
 1360                                 return (error);
 1361                 }
 1362         }
 1363         return (0);
 1364 }
 1365 
 1366 static int
 1367 link_elf_each_function_nameval(linker_file_t file,
 1368     linker_function_nameval_callback_t callback, void *opaque)
 1369 {
 1370         linker_symval_t symval;
 1371         elf_file_t ef = (elf_file_t)file;
 1372         const Elf_Sym* symp;
 1373         int i, error;
 1374 
 1375         /* Exhaustive search */
 1376         for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
 1377                 if (symp->st_value != 0 &&
 1378                     ELF_ST_TYPE(symp->st_info) == STT_FUNC) {
 1379                         error = link_elf_symbol_values(file,
 1380                             (c_linker_sym_t) symp, &symval);
 1381                         if (error != 0)
 1382                                 return (error);
 1383                         error = callback(file, i, &symval, opaque);
 1384                         if (error != 0)
 1385                                 return (error);
 1386                 }
 1387         }
 1388         return (0);
 1389 }
 1390 
 1391 #ifdef __ia64__
 1392 /*
 1393  * Each KLD has its own GP. The GP value for each load module is given by
 1394  * DT_PLTGOT on ia64. We need GP to construct function descriptors, but
 1395  * don't have direct access to the ELF file structure. The link_elf_get_gp()
 1396  * function returns the GP given a pointer to a generic linker file struct.
 1397  */
 1398 Elf_Addr
 1399 link_elf_get_gp(linker_file_t lf)
 1400 {
 1401         elf_file_t ef = (elf_file_t)lf;
 1402         return ((Elf_Addr)ef->got);
 1403 }
 1404 #endif
 1405 
 1406 const Elf_Sym *
 1407 elf_get_sym(linker_file_t lf, Elf_Size symidx)
 1408 {
 1409         elf_file_t ef = (elf_file_t)lf;
 1410 
 1411         if (symidx >= ef->nchains)
 1412                 return (NULL);
 1413         return (ef->symtab + symidx);
 1414 }
 1415 
 1416 const char *
 1417 elf_get_symname(linker_file_t lf, Elf_Size symidx)
 1418 {
 1419         elf_file_t ef = (elf_file_t)lf;
 1420         const Elf_Sym *sym;
 1421 
 1422         if (symidx >= ef->nchains)
 1423                 return (NULL);
 1424         sym = ef->symtab + symidx;
 1425         return (ef->strtab + sym->st_name);
 1426 }
 1427 
 1428 /*
 1429  * Symbol lookup function that can be used when the symbol index is known (ie
 1430  * in relocations). It uses the symbol index instead of doing a fully fledged
 1431  * hash table based lookup when such is valid. For example for local symbols.
 1432  * This is not only more efficient, it's also more correct. It's not always
 1433  * the case that the symbol can be found through the hash table.
 1434  */
 1435 static Elf_Addr
 1436 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps)
 1437 {
 1438         elf_file_t ef = (elf_file_t)lf;
 1439         const Elf_Sym *sym;
 1440         const char *symbol;
 1441 
 1442         /* Don't even try to lookup the symbol if the index is bogus. */
 1443         if (symidx >= ef->nchains)
 1444                 return (0);
 1445 
 1446         sym = ef->symtab + symidx;
 1447 
 1448         /*
 1449          * Don't do a full lookup when the symbol is local. It may even
 1450          * fail because it may not be found through the hash table.
 1451          */
 1452         if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
 1453                 /* Force lookup failure when we have an insanity. */
 1454                 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0)
 1455                         return (0);
 1456                 return ((Elf_Addr)ef->address + sym->st_value);
 1457         }
 1458 
 1459         /*
 1460          * XXX we can avoid doing a hash table based lookup for global
 1461          * symbols as well. This however is not always valid, so we'll
 1462          * just do it the hard way for now. Performance tweaks can
 1463          * always be added.
 1464          */
 1465 
 1466         symbol = ef->strtab + sym->st_name;
 1467 
 1468         /* Force a lookup failure if the symbol name is bogus. */
 1469         if (*symbol == 0)
 1470                 return (0);
 1471 
 1472         return ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
 1473 }
 1474 
 1475 static void
 1476 link_elf_reloc_local(linker_file_t lf)
 1477 {
 1478         const Elf_Rel *rellim;
 1479         const Elf_Rel *rel;
 1480         const Elf_Rela *relalim;
 1481         const Elf_Rela *rela;
 1482         elf_file_t ef = (elf_file_t)lf;
 1483 
 1484         /* Perform relocations without addend if there are any: */
 1485         if ((rel = ef->rel) != NULL) {
 1486                 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
 1487                 while (rel < rellim) {
 1488                         elf_reloc_local(lf, (Elf_Addr)ef->address, rel,
 1489                             ELF_RELOC_REL, elf_lookup);
 1490                         rel++;
 1491                 }
 1492         }
 1493 
 1494         /* Perform relocations with addend if there are any: */
 1495         if ((rela = ef->rela) != NULL) {
 1496                 relalim = (const Elf_Rela *)
 1497                     ((const char *)ef->rela + ef->relasize);
 1498                 while (rela < relalim) {
 1499                         elf_reloc_local(lf, (Elf_Addr)ef->address, rela,
 1500                             ELF_RELOC_RELA, elf_lookup);
 1501                         rela++;
 1502                 }
 1503         }
 1504 }
 1505 
 1506 static long
 1507 link_elf_symtab_get(linker_file_t lf, const Elf_Sym **symtab)
 1508 {
 1509         elf_file_t ef = (elf_file_t)lf;
 1510 
 1511         *symtab = ef->ddbsymtab;
 1512 
 1513         if (*symtab == NULL)
 1514                 return (0);
 1515 
 1516         return (ef->ddbsymcnt);
 1517 }
 1518     
 1519 static long
 1520 link_elf_strtab_get(linker_file_t lf, caddr_t *strtab)
 1521 {
 1522         elf_file_t ef = (elf_file_t)lf;
 1523 
 1524         *strtab = ef->ddbstrtab;
 1525 
 1526         if (*strtab == NULL)
 1527                 return (0);
 1528 
 1529         return (ef->ddbstrcnt);
 1530 }

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