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: stable/10/sys/kern/link_elf.c 296729 2016-03-12 17:23:15Z kib $");
   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 struct elf_set {
  127         Elf_Addr        es_start;
  128         Elf_Addr        es_stop;
  129         Elf_Addr        es_base;
  130         TAILQ_ENTRY(elf_set)    es_link;
  131 };
  132 
  133 TAILQ_HEAD(elf_set_head, elf_set);
  134 
  135 #include <kern/kern_ctf.c>
  136 
  137 static int      link_elf_link_common_finish(linker_file_t);
  138 static int      link_elf_link_preload(linker_class_t cls,
  139                                       const char *, linker_file_t *);
  140 static int      link_elf_link_preload_finish(linker_file_t);
  141 static int      link_elf_load_file(linker_class_t, const char *,
  142                     linker_file_t *);
  143 static int      link_elf_lookup_symbol(linker_file_t, const char *,
  144                     c_linker_sym_t *);
  145 static int      link_elf_symbol_values(linker_file_t, c_linker_sym_t,
  146                     linker_symval_t *);
  147 static int      link_elf_search_symbol(linker_file_t, caddr_t,
  148                     c_linker_sym_t *, long *);
  149 
  150 static void     link_elf_unload_file(linker_file_t);
  151 static void     link_elf_unload_preload(linker_file_t);
  152 static int      link_elf_lookup_set(linker_file_t, const char *,
  153                     void ***, void ***, int *);
  154 static int      link_elf_each_function_name(linker_file_t,
  155                     int (*)(const char *, void *), void *);
  156 static int      link_elf_each_function_nameval(linker_file_t,
  157                     linker_function_nameval_callback_t, void *);
  158 static void     link_elf_reloc_local(linker_file_t);
  159 static long     link_elf_symtab_get(linker_file_t, const Elf_Sym **);
  160 static long     link_elf_strtab_get(linker_file_t, caddr_t *);
  161 static int      elf_lookup(linker_file_t, Elf_Size, int, Elf_Addr *);
  162 
  163 static kobj_method_t link_elf_methods[] = {
  164         KOBJMETHOD(linker_lookup_symbol,        link_elf_lookup_symbol),
  165         KOBJMETHOD(linker_symbol_values,        link_elf_symbol_values),
  166         KOBJMETHOD(linker_search_symbol,        link_elf_search_symbol),
  167         KOBJMETHOD(linker_unload,               link_elf_unload_file),
  168         KOBJMETHOD(linker_load_file,            link_elf_load_file),
  169         KOBJMETHOD(linker_link_preload,         link_elf_link_preload),
  170         KOBJMETHOD(linker_link_preload_finish,  link_elf_link_preload_finish),
  171         KOBJMETHOD(linker_lookup_set,           link_elf_lookup_set),
  172         KOBJMETHOD(linker_each_function_name,   link_elf_each_function_name),
  173         KOBJMETHOD(linker_each_function_nameval, link_elf_each_function_nameval),
  174         KOBJMETHOD(linker_ctf_get,              link_elf_ctf_get),
  175         KOBJMETHOD(linker_symtab_get,           link_elf_symtab_get),
  176         KOBJMETHOD(linker_strtab_get,           link_elf_strtab_get),
  177         { 0, 0 }
  178 };
  179 
  180 static struct linker_class link_elf_class = {
  181 #if ELF_TARG_CLASS == ELFCLASS32
  182         "elf32",
  183 #else
  184         "elf64",
  185 #endif
  186         link_elf_methods, sizeof(struct elf_file)
  187 };
  188 
  189 static int      parse_dynamic(elf_file_t);
  190 static int      relocate_file(elf_file_t);
  191 static int      link_elf_preload_parse_symbols(elf_file_t);
  192 
  193 static struct elf_set_head set_pcpu_list;
  194 #ifdef VIMAGE
  195 static struct elf_set_head set_vnet_list;
  196 #endif
  197 
  198 static void
  199 elf_set_add(struct elf_set_head *list, Elf_Addr start, Elf_Addr stop, Elf_Addr base)
  200 {
  201         struct elf_set *set, *iter;
  202 
  203         set = malloc(sizeof(*set), M_LINKER, M_WAITOK);
  204         set->es_start = start;
  205         set->es_stop = stop;
  206         set->es_base = base;
  207 
  208         TAILQ_FOREACH(iter, list, es_link) {
  209 
  210                 KASSERT((set->es_start < iter->es_start && set->es_stop < iter->es_stop) ||
  211                     (set->es_start > iter->es_start && set->es_stop > iter->es_stop),
  212                     ("linker sets intersection: to insert: 0x%jx-0x%jx; inserted: 0x%jx-0x%jx",
  213                     (uintmax_t)set->es_start, (uintmax_t)set->es_stop,
  214                     (uintmax_t)iter->es_start, (uintmax_t)iter->es_stop));
  215 
  216                 if (iter->es_start > set->es_start) {
  217                         TAILQ_INSERT_BEFORE(iter, set, es_link);
  218                         break;
  219                 }
  220         }
  221 
  222         if (iter == NULL)
  223                 TAILQ_INSERT_TAIL(list, set, es_link);
  224 }
  225 
  226 static int
  227 elf_set_find(struct elf_set_head *list, Elf_Addr addr, Elf_Addr *start, Elf_Addr *base)
  228 {
  229         struct elf_set *set;
  230 
  231         TAILQ_FOREACH(set, list, es_link) {
  232                 if (addr < set->es_start)
  233                         return (0);
  234                 if (addr < set->es_stop) {
  235                         *start = set->es_start;
  236                         *base = set->es_base;
  237                         return (1);
  238                 }
  239         }
  240 
  241         return (0);
  242 }
  243 
  244 static void
  245 elf_set_delete(struct elf_set_head *list, Elf_Addr start)
  246 {
  247         struct elf_set *set;
  248 
  249         TAILQ_FOREACH(set, list, es_link) {
  250                 if (start < set->es_start)
  251                         break;
  252                 if (start == set->es_start) {
  253                         TAILQ_REMOVE(list, set, es_link);
  254                         free(set, M_LINKER);
  255                         return;
  256                 }
  257         }
  258         KASSERT(0, ("deleting unknown linker set (start = 0x%jx)",
  259             (uintmax_t)start));
  260 }
  261 
  262 #ifdef GDB
  263 static void     r_debug_state(struct r_debug *, struct link_map *);
  264 
  265 /*
  266  * A list of loaded modules for GDB to use for loading symbols.
  267  */
  268 struct r_debug r_debug;
  269 
  270 #define GDB_STATE(s) do {                               \
  271         r_debug.r_state = s; r_debug_state(NULL, NULL); \
  272 } while (0)
  273 
  274 /*
  275  * Function for the debugger to set a breakpoint on to gain control.
  276  */
  277 static void
  278 r_debug_state(struct r_debug *dummy_one __unused,
  279               struct link_map *dummy_two __unused)
  280 {
  281 }
  282 
  283 static void
  284 link_elf_add_gdb(struct link_map *l)
  285 {
  286         struct link_map *prev;
  287 
  288         l->l_next = NULL;
  289 
  290         if (r_debug.r_map == NULL) {
  291                 /* Add first. */
  292                 l->l_prev = NULL;
  293                 r_debug.r_map = l;
  294         } else {
  295                 /* Append to list. */
  296                 for (prev = r_debug.r_map;
  297                     prev->l_next != NULL;
  298                     prev = prev->l_next)
  299                         ;
  300                 l->l_prev = prev;
  301                 prev->l_next = l;
  302         }
  303 }
  304 
  305 static void
  306 link_elf_delete_gdb(struct link_map *l)
  307 {
  308         if (l->l_prev == NULL) {
  309                 /* Remove first. */
  310                 if ((r_debug.r_map = l->l_next) != NULL)
  311                         l->l_next->l_prev = NULL;
  312         } else {
  313                 /* Remove any but first. */
  314                 if ((l->l_prev->l_next = l->l_next) != NULL)
  315                         l->l_next->l_prev = l->l_prev;
  316         }
  317 }
  318 #endif /* GDB */
  319 
  320 #ifdef __ia64__
  321 Elf_Addr link_elf_get_gp(linker_file_t);
  322 #endif
  323 
  324 /*
  325  * The kernel symbol table starts here.
  326  */
  327 extern struct _dynamic _DYNAMIC;
  328 
  329 static void
  330 link_elf_error(const char *filename, const char *s)
  331 {
  332         if (filename == NULL)
  333                 printf("kldload: %s\n", s);
  334         else
  335                 printf("kldload: %s: %s\n", filename, s);
  336 }
  337 
  338 /*
  339  * Actions performed after linking/loading both the preloaded kernel and any
  340  * modules; whether preloaded or dynamicly loaded.
  341  */
  342 static int
  343 link_elf_link_common_finish(linker_file_t lf)
  344 {
  345 #ifdef GDB
  346         elf_file_t ef = (elf_file_t)lf;
  347         char *newfilename;
  348 #endif
  349         int error;
  350 
  351         /* Notify MD code that a module is being loaded. */
  352         error = elf_cpu_load_file(lf);
  353         if (error != 0)
  354                 return (error);
  355 
  356 #ifdef GDB
  357         GDB_STATE(RT_ADD);
  358         ef->gdb.l_addr = lf->address;
  359         newfilename = malloc(strlen(lf->filename) + 1, M_LINKER, M_WAITOK);
  360         strcpy(newfilename, lf->filename);
  361         ef->gdb.l_name = newfilename;
  362         ef->gdb.l_ld = ef->dynamic;
  363         link_elf_add_gdb(&ef->gdb);
  364         GDB_STATE(RT_CONSISTENT);
  365 #endif
  366 
  367         return (0);
  368 }
  369 
  370 static void
  371 link_elf_init(void* arg)
  372 {
  373         Elf_Dyn *dp;
  374         caddr_t modptr, baseptr, sizeptr;
  375         elf_file_t ef;
  376         char *modname;
  377 
  378         linker_add_class(&link_elf_class);
  379 
  380         dp = (Elf_Dyn *)&_DYNAMIC;
  381         modname = NULL;
  382         modptr = preload_search_by_type("elf" __XSTRING(__ELF_WORD_SIZE) " kernel");
  383         if (modptr == NULL)
  384                 modptr = preload_search_by_type("elf kernel");
  385         if (modptr != NULL)
  386                 modname = (char *)preload_search_info(modptr, MODINFO_NAME);
  387         if (modname == NULL)
  388                 modname = "kernel";
  389         linker_kernel_file = linker_make_file(modname, &link_elf_class);
  390         if (linker_kernel_file == NULL)
  391                 panic("%s: Can't create linker structures for kernel",
  392                     __func__);
  393 
  394         ef = (elf_file_t) linker_kernel_file;
  395         ef->preloaded = 1;
  396         ef->address = 0;
  397 #ifdef SPARSE_MAPPING
  398         ef->object = 0;
  399 #endif
  400         ef->dynamic = dp;
  401 
  402         if (dp != NULL)
  403                 parse_dynamic(ef);
  404         linker_kernel_file->address = (caddr_t) KERNBASE;
  405         linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;
  406 
  407         if (modptr != NULL) {
  408                 ef->modptr = modptr;
  409                 baseptr = preload_search_info(modptr, MODINFO_ADDR);
  410                 if (baseptr != NULL)
  411                         linker_kernel_file->address = *(caddr_t *)baseptr;
  412                 sizeptr = preload_search_info(modptr, MODINFO_SIZE);
  413                 if (sizeptr != NULL)
  414                         linker_kernel_file->size = *(size_t *)sizeptr;
  415         }
  416         (void)link_elf_preload_parse_symbols(ef);
  417 
  418 #ifdef GDB
  419         r_debug.r_map = NULL;
  420         r_debug.r_brk = r_debug_state;
  421         r_debug.r_state = RT_CONSISTENT;
  422 #endif
  423 
  424         (void)link_elf_link_common_finish(linker_kernel_file);
  425         linker_kernel_file->flags |= LINKER_FILE_LINKED;
  426         TAILQ_INIT(&set_pcpu_list);
  427 #ifdef VIMAGE
  428         TAILQ_INIT(&set_vnet_list);
  429 #endif
  430 }
  431 
  432 SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_THIRD, link_elf_init, 0);
  433 
  434 static int
  435 link_elf_preload_parse_symbols(elf_file_t ef)
  436 {
  437         caddr_t pointer;
  438         caddr_t ssym, esym, base;
  439         caddr_t strtab;
  440         int strcnt;
  441         Elf_Sym *symtab;
  442         int symcnt;
  443 
  444         if (ef->modptr == NULL)
  445                 return (0);
  446         pointer = preload_search_info(ef->modptr,
  447             MODINFO_METADATA | MODINFOMD_SSYM);
  448         if (pointer == NULL)
  449                 return (0);
  450         ssym = *(caddr_t *)pointer;
  451         pointer = preload_search_info(ef->modptr,
  452             MODINFO_METADATA | MODINFOMD_ESYM);
  453         if (pointer == NULL)
  454                 return (0);
  455         esym = *(caddr_t *)pointer;
  456 
  457         base = ssym;
  458 
  459         symcnt = *(long *)base;
  460         base += sizeof(long);
  461         symtab = (Elf_Sym *)base;
  462         base += roundup(symcnt, sizeof(long));
  463 
  464         if (base > esym || base < ssym) {
  465                 printf("Symbols are corrupt!\n");
  466                 return (EINVAL);
  467         }
  468 
  469         strcnt = *(long *)base;
  470         base += sizeof(long);
  471         strtab = base;
  472         base += roundup(strcnt, sizeof(long));
  473 
  474         if (base > esym || base < ssym) {
  475                 printf("Symbols are corrupt!\n");
  476                 return (EINVAL);
  477         }
  478 
  479         ef->ddbsymtab = symtab;
  480         ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
  481         ef->ddbstrtab = strtab;
  482         ef->ddbstrcnt = strcnt;
  483 
  484         return (0);
  485 }
  486 
  487 static int
  488 parse_dynamic(elf_file_t ef)
  489 {
  490         Elf_Dyn *dp;
  491         int plttype = DT_REL;
  492 
  493         for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
  494                 switch (dp->d_tag) {
  495                 case DT_HASH:
  496                 {
  497                         /* From src/libexec/rtld-elf/rtld.c */
  498                         const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
  499                             (ef->address + dp->d_un.d_ptr);
  500                         ef->nbuckets = hashtab[0];
  501                         ef->nchains = hashtab[1];
  502                         ef->buckets = hashtab + 2;
  503                         ef->chains = ef->buckets + ef->nbuckets;
  504                         break;
  505                 }
  506                 case DT_STRTAB:
  507                         ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr);
  508                         break;
  509                 case DT_STRSZ:
  510                         ef->strsz = dp->d_un.d_val;
  511                         break;
  512                 case DT_SYMTAB:
  513                         ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr);
  514                         break;
  515                 case DT_SYMENT:
  516                         if (dp->d_un.d_val != sizeof(Elf_Sym))
  517                                 return (ENOEXEC);
  518                         break;
  519                 case DT_PLTGOT:
  520                         ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr);
  521                         break;
  522                 case DT_REL:
  523                         ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
  524                         break;
  525                 case DT_RELSZ:
  526                         ef->relsize = dp->d_un.d_val;
  527                         break;
  528                 case DT_RELENT:
  529                         if (dp->d_un.d_val != sizeof(Elf_Rel))
  530                                 return (ENOEXEC);
  531                         break;
  532                 case DT_JMPREL:
  533                         ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
  534                         break;
  535                 case DT_PLTRELSZ:
  536                         ef->pltrelsize = dp->d_un.d_val;
  537                         break;
  538                 case DT_RELA:
  539                         ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr);
  540                         break;
  541                 case DT_RELASZ:
  542                         ef->relasize = dp->d_un.d_val;
  543                         break;
  544                 case DT_RELAENT:
  545                         if (dp->d_un.d_val != sizeof(Elf_Rela))
  546                                 return (ENOEXEC);
  547                         break;
  548                 case DT_PLTREL:
  549                         plttype = dp->d_un.d_val;
  550                         if (plttype != DT_REL && plttype != DT_RELA)
  551                                 return (ENOEXEC);
  552                         break;
  553 #ifdef GDB
  554                 case DT_DEBUG:
  555                         dp->d_un.d_ptr = (Elf_Addr)&r_debug;
  556                         break;
  557 #endif
  558                 }
  559         }
  560 
  561         if (plttype == DT_RELA) {
  562                 ef->pltrela = (const Elf_Rela *)ef->pltrel;
  563                 ef->pltrel = NULL;
  564                 ef->pltrelasize = ef->pltrelsize;
  565                 ef->pltrelsize = 0;
  566         }
  567 
  568         ef->ddbsymtab = ef->symtab;
  569         ef->ddbsymcnt = ef->nchains;
  570         ef->ddbstrtab = ef->strtab;
  571         ef->ddbstrcnt = ef->strsz;
  572 
  573         return (0);
  574 }
  575 
  576 static int
  577 parse_dpcpu(elf_file_t ef)
  578 {
  579         int count;
  580         int error;
  581 
  582         ef->pcpu_start = 0;
  583         ef->pcpu_stop = 0;
  584         error = link_elf_lookup_set(&ef->lf, "pcpu", (void ***)&ef->pcpu_start,
  585             (void ***)&ef->pcpu_stop, &count);
  586         /* Error just means there is no pcpu set to relocate. */
  587         if (error != 0)
  588                 return (0);
  589         count *= sizeof(void *);
  590         /*
  591          * Allocate space in the primary pcpu area.  Copy in our
  592          * initialization from the data section and then initialize
  593          * all per-cpu storage from that.
  594          */
  595         ef->pcpu_base = (Elf_Addr)(uintptr_t)dpcpu_alloc(count);
  596         if (ef->pcpu_base == 0)
  597                 return (ENOSPC);
  598         memcpy((void *)ef->pcpu_base, (void *)ef->pcpu_start, count);
  599         dpcpu_copy((void *)ef->pcpu_base, count);
  600         elf_set_add(&set_pcpu_list, ef->pcpu_start, ef->pcpu_stop,
  601             ef->pcpu_base);
  602 
  603         return (0);
  604 }
  605 
  606 #ifdef VIMAGE
  607 static int
  608 parse_vnet(elf_file_t ef)
  609 {
  610         int count;
  611         int error;
  612 
  613         ef->vnet_start = 0;
  614         ef->vnet_stop = 0;
  615         error = link_elf_lookup_set(&ef->lf, "vnet", (void ***)&ef->vnet_start,
  616             (void ***)&ef->vnet_stop, &count);
  617         /* Error just means there is no vnet data set to relocate. */
  618         if (error != 0)
  619                 return (0);
  620         count *= sizeof(void *);
  621         /*
  622          * Allocate space in the primary vnet area.  Copy in our
  623          * initialization from the data section and then initialize
  624          * all per-vnet storage from that.
  625          */
  626         ef->vnet_base = (Elf_Addr)(uintptr_t)vnet_data_alloc(count);
  627         if (ef->vnet_base == 0)
  628                 return (ENOSPC);
  629         memcpy((void *)ef->vnet_base, (void *)ef->vnet_start, count);
  630         vnet_data_copy((void *)ef->vnet_base, count);
  631         elf_set_add(&set_vnet_list, ef->vnet_start, ef->vnet_stop,
  632             ef->vnet_base);
  633 
  634         return (0);
  635 }
  636 #endif
  637 
  638 static int
  639 link_elf_link_preload(linker_class_t cls,
  640     const char* filename, linker_file_t *result)
  641 {
  642         caddr_t modptr, baseptr, sizeptr, dynptr;
  643         char *type;
  644         elf_file_t ef;
  645         linker_file_t lf;
  646         int error;
  647         vm_offset_t dp;
  648 
  649         /* Look to see if we have the file preloaded */
  650         modptr = preload_search_by_name(filename);
  651         if (modptr == NULL)
  652                 return (ENOENT);
  653 
  654         type = (char *)preload_search_info(modptr, MODINFO_TYPE);
  655         baseptr = preload_search_info(modptr, MODINFO_ADDR);
  656         sizeptr = preload_search_info(modptr, MODINFO_SIZE);
  657         dynptr = preload_search_info(modptr,
  658             MODINFO_METADATA | MODINFOMD_DYNAMIC);
  659         if (type == NULL ||
  660             (strcmp(type, "elf" __XSTRING(__ELF_WORD_SIZE) " module") != 0 &&
  661              strcmp(type, "elf module") != 0))
  662                 return (EFTYPE);
  663         if (baseptr == NULL || sizeptr == NULL || dynptr == NULL)
  664                 return (EINVAL);
  665 
  666         lf = linker_make_file(filename, &link_elf_class);
  667         if (lf == NULL)
  668                 return (ENOMEM);
  669 
  670         ef = (elf_file_t) lf;
  671         ef->preloaded = 1;
  672         ef->modptr = modptr;
  673         ef->address = *(caddr_t *)baseptr;
  674 #ifdef SPARSE_MAPPING
  675         ef->object = 0;
  676 #endif
  677         dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
  678         ef->dynamic = (Elf_Dyn *)dp;
  679         lf->address = ef->address;
  680         lf->size = *(size_t *)sizeptr;
  681 
  682         error = parse_dynamic(ef);
  683         if (error == 0)
  684                 error = parse_dpcpu(ef);
  685 #ifdef VIMAGE
  686         if (error == 0)
  687                 error = parse_vnet(ef);
  688 #endif
  689         if (error != 0) {
  690                 linker_file_unload(lf, LINKER_UNLOAD_FORCE);
  691                 return (error);
  692         }
  693         link_elf_reloc_local(lf);
  694         *result = lf;
  695         return (0);
  696 }
  697 
  698 static int
  699 link_elf_link_preload_finish(linker_file_t lf)
  700 {
  701         elf_file_t ef;
  702         int error;
  703 
  704         ef = (elf_file_t) lf;
  705         error = relocate_file(ef);
  706         if (error != 0)
  707                 return (error);
  708         (void)link_elf_preload_parse_symbols(ef);
  709 
  710         return (link_elf_link_common_finish(lf));
  711 }
  712 
  713 static int
  714 link_elf_load_file(linker_class_t cls, const char* filename,
  715     linker_file_t* result)
  716 {
  717         struct nameidata nd;
  718         struct thread* td = curthread;  /* XXX */
  719         Elf_Ehdr *hdr;
  720         caddr_t firstpage;
  721         int nbytes, i;
  722         Elf_Phdr *phdr;
  723         Elf_Phdr *phlimit;
  724         Elf_Phdr *segs[MAXSEGS];
  725         int nsegs;
  726         Elf_Phdr *phdyn;
  727         Elf_Phdr *phphdr;
  728         caddr_t mapbase;
  729         size_t mapsize;
  730         Elf_Off base_offset;
  731         Elf_Addr base_vaddr;
  732         Elf_Addr base_vlimit;
  733         int error = 0;
  734         ssize_t resid;
  735         int flags;
  736         elf_file_t ef;
  737         linker_file_t lf;
  738         Elf_Shdr *shdr;
  739         int symtabindex;
  740         int symstrindex;
  741         int symcnt;
  742         int strcnt;
  743 
  744         shdr = NULL;
  745         lf = NULL;
  746 
  747         NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, td);
  748         flags = FREAD;
  749         error = vn_open(&nd, &flags, 0, NULL);
  750         if (error != 0)
  751                 return (error);
  752         NDFREE(&nd, NDF_ONLY_PNBUF);
  753         if (nd.ni_vp->v_type != VREG) {
  754                 error = ENOEXEC;
  755                 firstpage = NULL;
  756                 goto out;
  757         }
  758 #ifdef MAC
  759         error = mac_kld_check_load(curthread->td_ucred, nd.ni_vp);
  760         if (error != 0) {
  761                 firstpage = NULL;
  762                 goto out;
  763         }
  764 #endif
  765 
  766         /*
  767          * Read the elf header from the file.
  768          */
  769         firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK);
  770         hdr = (Elf_Ehdr *)firstpage;
  771         error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0,
  772             UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
  773             &resid, td);
  774         nbytes = PAGE_SIZE - resid;
  775         if (error != 0)
  776                 goto out;
  777 
  778         if (!IS_ELF(*hdr)) {
  779                 error = ENOEXEC;
  780                 goto out;
  781         }
  782 
  783         if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
  784             hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
  785                 link_elf_error(filename, "Unsupported file layout");
  786                 error = ENOEXEC;
  787                 goto out;
  788         }
  789         if (hdr->e_ident[EI_VERSION] != EV_CURRENT ||
  790             hdr->e_version != EV_CURRENT) {
  791                 link_elf_error(filename, "Unsupported file version");
  792                 error = ENOEXEC;
  793                 goto out;
  794         }
  795         if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
  796                 error = ENOSYS;
  797                 goto out;
  798         }
  799         if (hdr->e_machine != ELF_TARG_MACH) {
  800                 link_elf_error(filename, "Unsupported machine");
  801                 error = ENOEXEC;
  802                 goto out;
  803         }
  804 
  805         /*
  806          * We rely on the program header being in the first page.
  807          * This is not strictly required by the ABI specification, but
  808          * it seems to always true in practice.  And, it simplifies
  809          * things considerably.
  810          */
  811         if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
  812               (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
  813               (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
  814                 link_elf_error(filename, "Unreadable program headers");
  815 
  816         /*
  817          * Scan the program header entries, and save key information.
  818          *
  819          * We rely on there being exactly two load segments, text and data,
  820          * in that order.
  821          */
  822         phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
  823         phlimit = phdr + hdr->e_phnum;
  824         nsegs = 0;
  825         phdyn = NULL;
  826         phphdr = NULL;
  827         while (phdr < phlimit) {
  828                 switch (phdr->p_type) {
  829                 case PT_LOAD:
  830                         if (nsegs == MAXSEGS) {
  831                                 link_elf_error(filename, "Too many sections");
  832                                 error = ENOEXEC;
  833                                 goto out;
  834                         }
  835                         /*
  836                          * XXX: We just trust they come in right order ??
  837                          */
  838                         segs[nsegs] = phdr;
  839                         ++nsegs;
  840                         break;
  841 
  842                 case PT_PHDR:
  843                         phphdr = phdr;
  844                         break;
  845 
  846                 case PT_DYNAMIC:
  847                         phdyn = phdr;
  848                         break;
  849 
  850                 case PT_INTERP:
  851                         error = ENOSYS;
  852                         goto out;
  853                 }
  854 
  855                 ++phdr;
  856         }
  857         if (phdyn == NULL) {
  858                 link_elf_error(filename, "Object is not dynamically-linked");
  859                 error = ENOEXEC;
  860                 goto out;
  861         }
  862         if (nsegs == 0) {
  863                 link_elf_error(filename, "No sections");
  864                 error = ENOEXEC;
  865                 goto out;
  866         }
  867 
  868         /*
  869          * Allocate the entire address space of the object, to stake
  870          * out our contiguous region, and to establish the base
  871          * address for relocation.
  872          */
  873         base_offset = trunc_page(segs[0]->p_offset);
  874         base_vaddr = trunc_page(segs[0]->p_vaddr);
  875         base_vlimit = round_page(segs[nsegs - 1]->p_vaddr +
  876             segs[nsegs - 1]->p_memsz);
  877         mapsize = base_vlimit - base_vaddr;
  878 
  879         lf = linker_make_file(filename, &link_elf_class);
  880         if (lf == NULL) {
  881                 error = ENOMEM;
  882                 goto out;
  883         }
  884 
  885         ef = (elf_file_t) lf;
  886 #ifdef SPARSE_MAPPING
  887         ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
  888         if (ef->object == NULL) {
  889                 error = ENOMEM;
  890                 goto out;
  891         }
  892         ef->address = (caddr_t) vm_map_min(kernel_map);
  893         error = vm_map_find(kernel_map, ef->object, 0,
  894             (vm_offset_t *) &ef->address, mapsize, 0, VMFS_OPTIMAL_SPACE,
  895             VM_PROT_ALL, VM_PROT_ALL, 0);
  896         if (error != 0) {
  897                 vm_object_deallocate(ef->object);
  898                 ef->object = 0;
  899                 goto out;
  900         }
  901 #else
  902         ef->address = malloc(mapsize, M_LINKER, M_WAITOK);
  903 #endif
  904         mapbase = ef->address;
  905 
  906         /*
  907          * Read the text and data sections and zero the bss.
  908          */
  909         for (i = 0; i < nsegs; i++) {
  910                 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
  911                 error = vn_rdwr(UIO_READ, nd.ni_vp,
  912                     segbase, segs[i]->p_filesz, segs[i]->p_offset,
  913                     UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
  914                     &resid, td);
  915                 if (error != 0)
  916                         goto out;
  917                 bzero(segbase + segs[i]->p_filesz,
  918                     segs[i]->p_memsz - segs[i]->p_filesz);
  919 
  920 #ifdef SPARSE_MAPPING
  921                 /*
  922                  * Wire down the pages
  923                  */
  924                 error = vm_map_wire(kernel_map,
  925                     (vm_offset_t) segbase,
  926                     (vm_offset_t) segbase + segs[i]->p_memsz,
  927                     VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
  928                 if (error != KERN_SUCCESS) {
  929                         error = ENOMEM;
  930                         goto out;
  931                 }
  932 #endif
  933         }
  934 
  935 #ifdef GPROF
  936         /* Update profiling information with the new text segment. */
  937         mtx_lock(&Giant);
  938         kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr +
  939             segs[0]->p_memsz));
  940         mtx_unlock(&Giant);
  941 #endif
  942 
  943         ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
  944 
  945         lf->address = ef->address;
  946         lf->size = mapsize;
  947 
  948         error = parse_dynamic(ef);
  949         if (error != 0)
  950                 goto out;
  951         error = parse_dpcpu(ef);
  952         if (error != 0)
  953                 goto out;
  954 #ifdef VIMAGE
  955         error = parse_vnet(ef);
  956         if (error != 0)
  957                 goto out;
  958 #endif
  959         link_elf_reloc_local(lf);
  960 
  961         VOP_UNLOCK(nd.ni_vp, 0);
  962         error = linker_load_dependencies(lf);
  963         vn_lock(nd.ni_vp, LK_EXCLUSIVE | LK_RETRY);
  964         if (error != 0)
  965                 goto out;
  966         error = relocate_file(ef);
  967         if (error != 0)
  968                 goto out;
  969 
  970         /*
  971          * Try and load the symbol table if it's present.  (you can
  972          * strip it!)
  973          */
  974         nbytes = hdr->e_shnum * hdr->e_shentsize;
  975         if (nbytes == 0 || hdr->e_shoff == 0)
  976                 goto nosyms;
  977         shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
  978         error = vn_rdwr(UIO_READ, nd.ni_vp,
  979             (caddr_t)shdr, nbytes, hdr->e_shoff,
  980             UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
  981             &resid, td);
  982         if (error != 0)
  983                 goto out;
  984         symtabindex = -1;
  985         symstrindex = -1;
  986         for (i = 0; i < hdr->e_shnum; i++) {
  987                 if (shdr[i].sh_type == SHT_SYMTAB) {
  988                         symtabindex = i;
  989                         symstrindex = shdr[i].sh_link;
  990                 }
  991         }
  992         if (symtabindex < 0 || symstrindex < 0)
  993                 goto nosyms;
  994 
  995         symcnt = shdr[symtabindex].sh_size;
  996         ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK);
  997         strcnt = shdr[symstrindex].sh_size;
  998         ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK);
  999 
 1000         error = vn_rdwr(UIO_READ, nd.ni_vp,
 1001             ef->symbase, symcnt, shdr[symtabindex].sh_offset,
 1002             UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
 1003             &resid, td);
 1004         if (error != 0)
 1005                 goto out;
 1006         error = vn_rdwr(UIO_READ, nd.ni_vp,
 1007             ef->strbase, strcnt, shdr[symstrindex].sh_offset,
 1008             UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
 1009             &resid, td);
 1010         if (error != 0)
 1011                 goto out;
 1012 
 1013         ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
 1014         ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
 1015         ef->ddbstrcnt = strcnt;
 1016         ef->ddbstrtab = ef->strbase;
 1017 
 1018 nosyms:
 1019         error = link_elf_link_common_finish(lf);
 1020         if (error != 0)
 1021                 goto out;
 1022 
 1023         *result = lf;
 1024 
 1025 out:
 1026         VOP_UNLOCK(nd.ni_vp, 0);
 1027         vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
 1028         if (error != 0 && lf != NULL)
 1029                 linker_file_unload(lf, LINKER_UNLOAD_FORCE);
 1030         free(shdr, M_LINKER);
 1031         free(firstpage, M_LINKER);
 1032 
 1033         return (error);
 1034 }
 1035 
 1036 Elf_Addr
 1037 elf_relocaddr(linker_file_t lf, Elf_Addr x)
 1038 {
 1039         elf_file_t ef;
 1040 
 1041         ef = (elf_file_t)lf;
 1042         if (x >= ef->pcpu_start && x < ef->pcpu_stop)
 1043                 return ((x - ef->pcpu_start) + ef->pcpu_base);
 1044 #ifdef VIMAGE
 1045         if (x >= ef->vnet_start && x < ef->vnet_stop)
 1046                 return ((x - ef->vnet_start) + ef->vnet_base);
 1047 #endif
 1048         return (x);
 1049 }
 1050 
 1051 
 1052 static void
 1053 link_elf_unload_file(linker_file_t file)
 1054 {
 1055         elf_file_t ef = (elf_file_t) file;
 1056 
 1057         if (ef->pcpu_base != 0) {
 1058                 dpcpu_free((void *)ef->pcpu_base,
 1059                     ef->pcpu_stop - ef->pcpu_start);
 1060                 elf_set_delete(&set_pcpu_list, ef->pcpu_start);
 1061         }
 1062 #ifdef VIMAGE
 1063         if (ef->vnet_base != 0) {
 1064                 vnet_data_free((void *)ef->vnet_base,
 1065                     ef->vnet_stop - ef->vnet_start);
 1066                 elf_set_delete(&set_vnet_list, ef->vnet_start);
 1067         }
 1068 #endif
 1069 #ifdef GDB
 1070         if (ef->gdb.l_ld != NULL) {
 1071                 GDB_STATE(RT_DELETE);
 1072                 free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER);
 1073                 link_elf_delete_gdb(&ef->gdb);
 1074                 GDB_STATE(RT_CONSISTENT);
 1075         }
 1076 #endif
 1077 
 1078         /* Notify MD code that a module is being unloaded. */
 1079         elf_cpu_unload_file(file);
 1080 
 1081         if (ef->preloaded) {
 1082                 link_elf_unload_preload(file);
 1083                 return;
 1084         }
 1085 
 1086 #ifdef SPARSE_MAPPING
 1087         if (ef->object != NULL) {
 1088                 vm_map_remove(kernel_map, (vm_offset_t) ef->address,
 1089                     (vm_offset_t) ef->address
 1090                     + (ef->object->size << PAGE_SHIFT));
 1091         }
 1092 #else
 1093         free(ef->address, M_LINKER);
 1094 #endif
 1095         free(ef->symbase, M_LINKER);
 1096         free(ef->strbase, M_LINKER);
 1097         free(ef->ctftab, M_LINKER);
 1098         free(ef->ctfoff, M_LINKER);
 1099         free(ef->typoff, M_LINKER);
 1100 }
 1101 
 1102 static void
 1103 link_elf_unload_preload(linker_file_t file)
 1104 {
 1105         if (file->filename != NULL)
 1106                 preload_delete_name(file->filename);
 1107 }
 1108 
 1109 static const char *
 1110 symbol_name(elf_file_t ef, Elf_Size r_info)
 1111 {
 1112         const Elf_Sym *ref;
 1113 
 1114         if (ELF_R_SYM(r_info)) {
 1115                 ref = ef->symtab + ELF_R_SYM(r_info);
 1116                 return (ef->strtab + ref->st_name);
 1117         }
 1118         return (NULL);
 1119 }
 1120 
 1121 static int
 1122 relocate_file(elf_file_t ef)
 1123 {
 1124         const Elf_Rel *rellim;
 1125         const Elf_Rel *rel;
 1126         const Elf_Rela *relalim;
 1127         const Elf_Rela *rela;
 1128         const char *symname;
 1129 
 1130         /* Perform relocations without addend if there are any: */
 1131         rel = ef->rel;
 1132         if (rel != NULL) {
 1133                 rellim = (const Elf_Rel *)
 1134                     ((const char *)ef->rel + ef->relsize);
 1135                 while (rel < rellim) {
 1136                         if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel,
 1137                             ELF_RELOC_REL, elf_lookup)) {
 1138                                 symname = symbol_name(ef, rel->r_info);
 1139                                 printf("link_elf: symbol %s undefined\n", symname);
 1140                                 return (ENOENT);
 1141                         }
 1142                         rel++;
 1143                 }
 1144         }
 1145 
 1146         /* Perform relocations with addend if there are any: */
 1147         rela = ef->rela;
 1148         if (rela != NULL) {
 1149                 relalim = (const Elf_Rela *)
 1150                     ((const char *)ef->rela + ef->relasize);
 1151                 while (rela < relalim) {
 1152                         if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela,
 1153                             ELF_RELOC_RELA, elf_lookup)) {
 1154                                 symname = symbol_name(ef, rela->r_info);
 1155                                 printf("link_elf: symbol %s undefined\n",
 1156                                     symname);
 1157                                 return (ENOENT);
 1158                         }
 1159                         rela++;
 1160                 }
 1161         }
 1162 
 1163         /* Perform PLT relocations without addend if there are any: */
 1164         rel = ef->pltrel;
 1165         if (rel != NULL) {
 1166                 rellim = (const Elf_Rel *)
 1167                     ((const char *)ef->pltrel + ef->pltrelsize);
 1168                 while (rel < rellim) {
 1169                         if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel,
 1170                             ELF_RELOC_REL, elf_lookup)) {
 1171                                 symname = symbol_name(ef, rel->r_info);
 1172                                 printf("link_elf: symbol %s undefined\n",
 1173                                     symname);
 1174                                 return (ENOENT);
 1175                         }
 1176                         rel++;
 1177                 }
 1178         }
 1179 
 1180         /* Perform relocations with addend if there are any: */
 1181         rela = ef->pltrela;
 1182         if (rela != NULL) {
 1183                 relalim = (const Elf_Rela *)
 1184                     ((const char *)ef->pltrela + ef->pltrelasize);
 1185                 while (rela < relalim) {
 1186                         if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela,
 1187                             ELF_RELOC_RELA, elf_lookup)) {
 1188                                 symname = symbol_name(ef, rela->r_info);
 1189                                 printf("link_elf: symbol %s undefined\n",
 1190                                     symname);
 1191                                 return (ENOENT);
 1192                         }
 1193                         rela++;
 1194                 }
 1195         }
 1196 
 1197         return (0);
 1198 }
 1199 
 1200 /*
 1201  * Hash function for symbol table lookup.  Don't even think about changing
 1202  * this.  It is specified by the System V ABI.
 1203  */
 1204 static unsigned long
 1205 elf_hash(const char *name)
 1206 {
 1207         const unsigned char *p = (const unsigned char *) name;
 1208         unsigned long h = 0;
 1209         unsigned long g;
 1210 
 1211         while (*p != '\0') {
 1212                 h = (h << 4) + *p++;
 1213                 if ((g = h & 0xf0000000) != 0)
 1214                         h ^= g >> 24;
 1215                 h &= ~g;
 1216         }
 1217         return (h);
 1218 }
 1219 
 1220 static int
 1221 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym)
 1222 {
 1223         elf_file_t ef = (elf_file_t) lf;
 1224         unsigned long symnum;
 1225         const Elf_Sym* symp;
 1226         const char *strp;
 1227         unsigned long hash;
 1228         int i;
 1229 
 1230         /* If we don't have a hash, bail. */
 1231         if (ef->buckets == NULL || ef->nbuckets == 0) {
 1232                 printf("link_elf_lookup_symbol: missing symbol hash table\n");
 1233                 return (ENOENT);
 1234         }
 1235 
 1236         /* First, search hashed global symbols */
 1237         hash = elf_hash(name);
 1238         symnum = ef->buckets[hash % ef->nbuckets];
 1239 
 1240         while (symnum != STN_UNDEF) {
 1241                 if (symnum >= ef->nchains) {
 1242                         printf("%s: corrupt symbol table\n", __func__);
 1243                         return (ENOENT);
 1244                 }
 1245 
 1246                 symp = ef->symtab + symnum;
 1247                 if (symp->st_name == 0) {
 1248                         printf("%s: corrupt symbol table\n", __func__);
 1249                         return (ENOENT);
 1250                 }
 1251 
 1252                 strp = ef->strtab + symp->st_name;
 1253 
 1254                 if (strcmp(name, strp) == 0) {
 1255                         if (symp->st_shndx != SHN_UNDEF ||
 1256                             (symp->st_value != 0 &&
 1257                              ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
 1258                                 *sym = (c_linker_sym_t) symp;
 1259                                 return (0);
 1260                         }
 1261                         return (ENOENT);
 1262                 }
 1263 
 1264                 symnum = ef->chains[symnum];
 1265         }
 1266 
 1267         /* If we have not found it, look at the full table (if loaded) */
 1268         if (ef->symtab == ef->ddbsymtab)
 1269                 return (ENOENT);
 1270 
 1271         /* Exhaustive search */
 1272         for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
 1273                 strp = ef->ddbstrtab + symp->st_name;
 1274                 if (strcmp(name, strp) == 0) {
 1275                         if (symp->st_shndx != SHN_UNDEF ||
 1276                             (symp->st_value != 0 &&
 1277                              ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
 1278                                 *sym = (c_linker_sym_t) symp;
 1279                                 return (0);
 1280                         }
 1281                         return (ENOENT);
 1282                 }
 1283         }
 1284 
 1285         return (ENOENT);
 1286 }
 1287 
 1288 static int
 1289 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym,
 1290     linker_symval_t *symval)
 1291 {
 1292         elf_file_t ef = (elf_file_t) lf;
 1293         const Elf_Sym* es = (const Elf_Sym*) sym;
 1294 
 1295         if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) {
 1296                 symval->name = ef->strtab + es->st_name;
 1297                 symval->value = (caddr_t) ef->address + es->st_value;
 1298                 symval->size = es->st_size;
 1299                 return (0);
 1300         }
 1301         if (ef->symtab == ef->ddbsymtab)
 1302                 return (ENOENT);
 1303         if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
 1304                 symval->name = ef->ddbstrtab + es->st_name;
 1305                 symval->value = (caddr_t) ef->address + es->st_value;
 1306                 symval->size = es->st_size;
 1307                 return (0);
 1308         }
 1309         return (ENOENT);
 1310 }
 1311 
 1312 static int
 1313 link_elf_search_symbol(linker_file_t lf, caddr_t value,
 1314     c_linker_sym_t *sym, long *diffp)
 1315 {
 1316         elf_file_t ef = (elf_file_t) lf;
 1317         u_long off = (uintptr_t) (void *) value;
 1318         u_long diff = off;
 1319         u_long st_value;
 1320         const Elf_Sym* es;
 1321         const Elf_Sym* best = 0;
 1322         int i;
 1323 
 1324         for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
 1325                 if (es->st_name == 0)
 1326                         continue;
 1327                 st_value = es->st_value + (uintptr_t) (void *) ef->address;
 1328                 if (off >= st_value) {
 1329                         if (off - st_value < diff) {
 1330                                 diff = off - st_value;
 1331                                 best = es;
 1332                                 if (diff == 0)
 1333                                         break;
 1334                         } else if (off - st_value == diff) {
 1335                                 best = es;
 1336                         }
 1337                 }
 1338         }
 1339         if (best == 0)
 1340                 *diffp = off;
 1341         else
 1342                 *diffp = diff;
 1343         *sym = (c_linker_sym_t) best;
 1344 
 1345         return (0);
 1346 }
 1347 
 1348 /*
 1349  * Look up a linker set on an ELF system.
 1350  */
 1351 static int
 1352 link_elf_lookup_set(linker_file_t lf, const char *name,
 1353     void ***startp, void ***stopp, int *countp)
 1354 {
 1355         c_linker_sym_t sym;
 1356         linker_symval_t symval;
 1357         char *setsym;
 1358         void **start, **stop;
 1359         int len, error = 0, count;
 1360 
 1361         len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
 1362         setsym = malloc(len, M_LINKER, M_WAITOK);
 1363 
 1364         /* get address of first entry */
 1365         snprintf(setsym, len, "%s%s", "__start_set_", name);
 1366         error = link_elf_lookup_symbol(lf, setsym, &sym);
 1367         if (error != 0)
 1368                 goto out;
 1369         link_elf_symbol_values(lf, sym, &symval);
 1370         if (symval.value == 0) {
 1371                 error = ESRCH;
 1372                 goto out;
 1373         }
 1374         start = (void **)symval.value;
 1375 
 1376         /* get address of last entry */
 1377         snprintf(setsym, len, "%s%s", "__stop_set_", name);
 1378         error = link_elf_lookup_symbol(lf, setsym, &sym);
 1379         if (error != 0)
 1380                 goto out;
 1381         link_elf_symbol_values(lf, sym, &symval);
 1382         if (symval.value == 0) {
 1383                 error = ESRCH;
 1384                 goto out;
 1385         }
 1386         stop = (void **)symval.value;
 1387 
 1388         /* and the number of entries */
 1389         count = stop - start;
 1390 
 1391         /* and copy out */
 1392         if (startp != NULL)
 1393                 *startp = start;
 1394         if (stopp != NULL)
 1395                 *stopp = stop;
 1396         if (countp != NULL)
 1397                 *countp = count;
 1398 
 1399 out:
 1400         free(setsym, M_LINKER);
 1401         return (error);
 1402 }
 1403 
 1404 static int
 1405 link_elf_each_function_name(linker_file_t file,
 1406   int (*callback)(const char *, void *), void *opaque)
 1407 {
 1408         elf_file_t ef = (elf_file_t)file;
 1409         const Elf_Sym *symp;
 1410         int i, error;
 1411 
 1412         /* Exhaustive search */
 1413         for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
 1414                 if (symp->st_value != 0 &&
 1415                     ELF_ST_TYPE(symp->st_info) == STT_FUNC) {
 1416                         error = callback(ef->ddbstrtab + symp->st_name, opaque);
 1417                         if (error != 0)
 1418                                 return (error);
 1419                 }
 1420         }
 1421         return (0);
 1422 }
 1423 
 1424 static int
 1425 link_elf_each_function_nameval(linker_file_t file,
 1426     linker_function_nameval_callback_t callback, void *opaque)
 1427 {
 1428         linker_symval_t symval;
 1429         elf_file_t ef = (elf_file_t)file;
 1430         const Elf_Sym* symp;
 1431         int i, error;
 1432 
 1433         /* Exhaustive search */
 1434         for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
 1435                 if (symp->st_value != 0 &&
 1436                     ELF_ST_TYPE(symp->st_info) == STT_FUNC) {
 1437                         error = link_elf_symbol_values(file,
 1438                             (c_linker_sym_t) symp, &symval);
 1439                         if (error != 0)
 1440                                 return (error);
 1441                         error = callback(file, i, &symval, opaque);
 1442                         if (error != 0)
 1443                                 return (error);
 1444                 }
 1445         }
 1446         return (0);
 1447 }
 1448 
 1449 #ifdef __ia64__
 1450 /*
 1451  * Each KLD has its own GP. The GP value for each load module is given by
 1452  * DT_PLTGOT on ia64. We need GP to construct function descriptors, but
 1453  * don't have direct access to the ELF file structure. The link_elf_get_gp()
 1454  * function returns the GP given a pointer to a generic linker file struct.
 1455  */
 1456 Elf_Addr
 1457 link_elf_get_gp(linker_file_t lf)
 1458 {
 1459         elf_file_t ef = (elf_file_t)lf;
 1460         return ((Elf_Addr)ef->got);
 1461 }
 1462 #endif
 1463 
 1464 const Elf_Sym *
 1465 elf_get_sym(linker_file_t lf, Elf_Size symidx)
 1466 {
 1467         elf_file_t ef = (elf_file_t)lf;
 1468 
 1469         if (symidx >= ef->nchains)
 1470                 return (NULL);
 1471         return (ef->symtab + symidx);
 1472 }
 1473 
 1474 const char *
 1475 elf_get_symname(linker_file_t lf, Elf_Size symidx)
 1476 {
 1477         elf_file_t ef = (elf_file_t)lf;
 1478         const Elf_Sym *sym;
 1479 
 1480         if (symidx >= ef->nchains)
 1481                 return (NULL);
 1482         sym = ef->symtab + symidx;
 1483         return (ef->strtab + sym->st_name);
 1484 }
 1485 
 1486 /*
 1487  * Symbol lookup function that can be used when the symbol index is known (ie
 1488  * in relocations). It uses the symbol index instead of doing a fully fledged
 1489  * hash table based lookup when such is valid. For example for local symbols.
 1490  * This is not only more efficient, it's also more correct. It's not always
 1491  * the case that the symbol can be found through the hash table.
 1492  */
 1493 static int
 1494 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *res)
 1495 {
 1496         elf_file_t ef = (elf_file_t)lf;
 1497         const Elf_Sym *sym;
 1498         const char *symbol;
 1499         Elf_Addr addr, start, base;
 1500 
 1501         /* Don't even try to lookup the symbol if the index is bogus. */
 1502         if (symidx >= ef->nchains) {
 1503                 *res = 0;
 1504                 return (EINVAL);
 1505         }
 1506 
 1507         sym = ef->symtab + symidx;
 1508 
 1509         /*
 1510          * Don't do a full lookup when the symbol is local. It may even
 1511          * fail because it may not be found through the hash table.
 1512          */
 1513         if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
 1514                 /* Force lookup failure when we have an insanity. */
 1515                 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0) {
 1516                         *res = 0;
 1517                         return (EINVAL);
 1518                 }
 1519                 *res = ((Elf_Addr)ef->address + sym->st_value);
 1520                 return (0);
 1521         }
 1522 
 1523         /*
 1524          * XXX we can avoid doing a hash table based lookup for global
 1525          * symbols as well. This however is not always valid, so we'll
 1526          * just do it the hard way for now. Performance tweaks can
 1527          * always be added.
 1528          */
 1529 
 1530         symbol = ef->strtab + sym->st_name;
 1531 
 1532         /* Force a lookup failure if the symbol name is bogus. */
 1533         if (*symbol == 0) {
 1534                 *res = 0;
 1535                 return (EINVAL);
 1536         }
 1537 
 1538         addr = ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
 1539         if (addr == 0 && ELF_ST_BIND(sym->st_info) != STB_WEAK) {
 1540                 *res = 0;
 1541                 return (EINVAL);
 1542         }
 1543 
 1544         if (elf_set_find(&set_pcpu_list, addr, &start, &base))
 1545                 addr = addr - start + base;
 1546 #ifdef VIMAGE
 1547         else if (elf_set_find(&set_vnet_list, addr, &start, &base))
 1548                 addr = addr - start + base;
 1549 #endif
 1550         *res = addr;
 1551         return (0);
 1552 }
 1553 
 1554 static void
 1555 link_elf_reloc_local(linker_file_t lf)
 1556 {
 1557         const Elf_Rel *rellim;
 1558         const Elf_Rel *rel;
 1559         const Elf_Rela *relalim;
 1560         const Elf_Rela *rela;
 1561         elf_file_t ef = (elf_file_t)lf;
 1562 
 1563         /* Perform relocations without addend if there are any: */
 1564         if ((rel = ef->rel) != NULL) {
 1565                 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
 1566                 while (rel < rellim) {
 1567                         elf_reloc_local(lf, (Elf_Addr)ef->address, rel,
 1568                             ELF_RELOC_REL, elf_lookup);
 1569                         rel++;
 1570                 }
 1571         }
 1572 
 1573         /* Perform relocations with addend if there are any: */
 1574         if ((rela = ef->rela) != NULL) {
 1575                 relalim = (const Elf_Rela *)
 1576                     ((const char *)ef->rela + ef->relasize);
 1577                 while (rela < relalim) {
 1578                         elf_reloc_local(lf, (Elf_Addr)ef->address, rela,
 1579                             ELF_RELOC_RELA, elf_lookup);
 1580                         rela++;
 1581                 }
 1582         }
 1583 }
 1584 
 1585 static long
 1586 link_elf_symtab_get(linker_file_t lf, const Elf_Sym **symtab)
 1587 {
 1588         elf_file_t ef = (elf_file_t)lf;
 1589 
 1590         *symtab = ef->ddbsymtab;
 1591 
 1592         if (*symtab == NULL)
 1593                 return (0);
 1594 
 1595         return (ef->ddbsymcnt);
 1596 }
 1597 
 1598 static long
 1599 link_elf_strtab_get(linker_file_t lf, caddr_t *strtab)
 1600 {
 1601         elf_file_t ef = (elf_file_t)lf;
 1602 
 1603         *strtab = ef->ddbstrtab;
 1604 
 1605         if (*strtab == NULL)
 1606                 return (0);
 1607 
 1608         return (ef->ddbstrcnt);
 1609 }

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