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("$FreeBSD$");
   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 Elf_Addr elf_lookup(linker_file_t, Elf_Size, int);
  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 #if 0   /* this will be more trouble than it's worth for now */
  706         for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
  707                 if (dp->d_tag != DT_NEEDED)
  708                         continue;
  709                 modname = ef->strtab + dp->d_un.d_val;
  710                 error = linker_load_module(modname, lf);
  711                 if (error != 0)
  712                         goto out;
  713     }
  714 #endif
  715         error = relocate_file(ef);
  716         if (error != 0)
  717                 return (error);
  718         (void)link_elf_preload_parse_symbols(ef);
  719 
  720         return (link_elf_link_common_finish(lf));
  721 }
  722 
  723 static int
  724 link_elf_load_file(linker_class_t cls, const char* filename,
  725     linker_file_t* result)
  726 {
  727         struct nameidata nd;
  728         struct thread* td = curthread;  /* XXX */
  729         Elf_Ehdr *hdr;
  730         caddr_t firstpage;
  731         int nbytes, i;
  732         Elf_Phdr *phdr;
  733         Elf_Phdr *phlimit;
  734         Elf_Phdr *segs[MAXSEGS];
  735         int nsegs;
  736         Elf_Phdr *phdyn;
  737         Elf_Phdr *phphdr;
  738         caddr_t mapbase;
  739         size_t mapsize;
  740         Elf_Off base_offset;
  741         Elf_Addr base_vaddr;
  742         Elf_Addr base_vlimit;
  743         int error = 0;
  744         ssize_t resid;
  745         int flags;
  746         elf_file_t ef;
  747         linker_file_t lf;
  748         Elf_Shdr *shdr;
  749         int symtabindex;
  750         int symstrindex;
  751         int symcnt;
  752         int strcnt;
  753         int vfslocked;
  754 
  755         shdr = NULL;
  756         lf = NULL;
  757 
  758         NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, filename, td);
  759         flags = FREAD;
  760         error = vn_open(&nd, &flags, 0, NULL);
  761         if (error != 0)
  762                 return (error);
  763         vfslocked = NDHASGIANT(&nd);
  764         NDFREE(&nd, NDF_ONLY_PNBUF);
  765         if (nd.ni_vp->v_type != VREG) {
  766                 error = ENOEXEC;
  767                 firstpage = NULL;
  768                 goto out;
  769         }
  770 #ifdef MAC
  771         error = mac_kld_check_load(curthread->td_ucred, nd.ni_vp);
  772         if (error != 0) {
  773                 firstpage = NULL;
  774                 goto out;
  775         }
  776 #endif
  777 
  778         /*
  779          * Read the elf header from the file.
  780          */
  781         firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK);
  782         hdr = (Elf_Ehdr *)firstpage;
  783         error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0,
  784             UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
  785             &resid, td);
  786         nbytes = PAGE_SIZE - resid;
  787         if (error != 0)
  788                 goto out;
  789 
  790         if (!IS_ELF(*hdr)) {
  791                 error = ENOEXEC;
  792                 goto out;
  793         }
  794 
  795         if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
  796             hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
  797                 link_elf_error(filename, "Unsupported file layout");
  798                 error = ENOEXEC;
  799                 goto out;
  800         }
  801         if (hdr->e_ident[EI_VERSION] != EV_CURRENT ||
  802             hdr->e_version != EV_CURRENT) {
  803                 link_elf_error(filename, "Unsupported file version");
  804                 error = ENOEXEC;
  805                 goto out;
  806         }
  807         if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
  808                 error = ENOSYS;
  809                 goto out;
  810         }
  811         if (hdr->e_machine != ELF_TARG_MACH) {
  812                 link_elf_error(filename, "Unsupported machine");
  813                 error = ENOEXEC;
  814                 goto out;
  815         }
  816 
  817         /*
  818          * We rely on the program header being in the first page.
  819          * This is not strictly required by the ABI specification, but
  820          * it seems to always true in practice.  And, it simplifies
  821          * things considerably.
  822          */
  823         if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
  824               (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
  825               (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
  826                 link_elf_error(filename, "Unreadable program headers");
  827 
  828         /*
  829          * Scan the program header entries, and save key information.
  830          *
  831          * We rely on there being exactly two load segments, text and data,
  832          * in that order.
  833          */
  834         phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
  835         phlimit = phdr + hdr->e_phnum;
  836         nsegs = 0;
  837         phdyn = NULL;
  838         phphdr = NULL;
  839         while (phdr < phlimit) {
  840                 switch (phdr->p_type) {
  841                 case PT_LOAD:
  842                         if (nsegs == MAXSEGS) {
  843                                 link_elf_error(filename, "Too many sections");
  844                                 error = ENOEXEC;
  845                                 goto out;
  846                         }
  847                         /*
  848                          * XXX: We just trust they come in right order ??
  849                          */
  850                         segs[nsegs] = phdr;
  851                         ++nsegs;
  852                         break;
  853 
  854                 case PT_PHDR:
  855                         phphdr = phdr;
  856                         break;
  857 
  858                 case PT_DYNAMIC:
  859                         phdyn = phdr;
  860                         break;
  861 
  862                 case PT_INTERP:
  863                         error = ENOSYS;
  864                         goto out;
  865                 }
  866 
  867                 ++phdr;
  868         }
  869         if (phdyn == NULL) {
  870                 link_elf_error(filename, "Object is not dynamically-linked");
  871                 error = ENOEXEC;
  872                 goto out;
  873         }
  874         if (nsegs == 0) {
  875                 link_elf_error(filename, "No sections");
  876                 error = ENOEXEC;
  877                 goto out;
  878         }
  879 
  880         /*
  881          * Allocate the entire address space of the object, to stake
  882          * out our contiguous region, and to establish the base
  883          * address for relocation.
  884          */
  885         base_offset = trunc_page(segs[0]->p_offset);
  886         base_vaddr = trunc_page(segs[0]->p_vaddr);
  887         base_vlimit = round_page(segs[nsegs - 1]->p_vaddr +
  888             segs[nsegs - 1]->p_memsz);
  889         mapsize = base_vlimit - base_vaddr;
  890 
  891         lf = linker_make_file(filename, &link_elf_class);
  892         if (lf == NULL) {
  893                 error = ENOMEM;
  894                 goto out;
  895         }
  896 
  897         ef = (elf_file_t) lf;
  898 #ifdef SPARSE_MAPPING
  899         ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
  900         if (ef->object == NULL) {
  901                 error = ENOMEM;
  902                 goto out;
  903         }
  904         ef->address = (caddr_t) vm_map_min(kernel_map);
  905         error = vm_map_find(kernel_map, ef->object, 0,
  906             (vm_offset_t *) &ef->address, mapsize, 1,
  907             VM_PROT_ALL, VM_PROT_ALL, 0);
  908         if (error != 0) {
  909                 vm_object_deallocate(ef->object);
  910                 ef->object = 0;
  911                 goto out;
  912         }
  913 #else
  914         ef->address = malloc(mapsize, M_LINKER, M_WAITOK);
  915 #endif
  916         mapbase = ef->address;
  917 
  918         /*
  919          * Read the text and data sections and zero the bss.
  920          */
  921         for (i = 0; i < nsegs; i++) {
  922                 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
  923                 error = vn_rdwr(UIO_READ, nd.ni_vp,
  924                     segbase, segs[i]->p_filesz, segs[i]->p_offset,
  925                     UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
  926                     &resid, td);
  927                 if (error != 0)
  928                         goto out;
  929                 bzero(segbase + segs[i]->p_filesz,
  930                     segs[i]->p_memsz - segs[i]->p_filesz);
  931 
  932 #ifdef SPARSE_MAPPING
  933                 /*
  934                  * Wire down the pages
  935                  */
  936                 error = vm_map_wire(kernel_map,
  937                     (vm_offset_t) segbase,
  938                     (vm_offset_t) segbase + segs[i]->p_memsz,
  939                     VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
  940                 if (error != KERN_SUCCESS) {
  941                         error = ENOMEM;
  942                         goto out;
  943                 }
  944 #endif
  945         }
  946 
  947 #ifdef GPROF
  948         /* Update profiling information with the new text segment. */
  949         mtx_lock(&Giant);
  950         kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr +
  951             segs[0]->p_memsz));
  952         mtx_unlock(&Giant);
  953 #endif
  954 
  955         ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
  956 
  957         lf->address = ef->address;
  958         lf->size = mapsize;
  959 
  960         error = parse_dynamic(ef);
  961         if (error != 0)
  962                 goto out;
  963         error = parse_dpcpu(ef);
  964         if (error != 0)
  965                 goto out;
  966 #ifdef VIMAGE
  967         error = parse_vnet(ef);
  968         if (error != 0)
  969                 goto out;
  970 #endif
  971         link_elf_reloc_local(lf);
  972 
  973         VOP_UNLOCK(nd.ni_vp, 0);
  974         error = linker_load_dependencies(lf);
  975         vn_lock(nd.ni_vp, LK_EXCLUSIVE | LK_RETRY);
  976         if (error != 0)
  977                 goto out;
  978 #if 0   /* this will be more trouble than it's worth for now */
  979         for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
  980                 if (dp->d_tag != DT_NEEDED)
  981                         continue;
  982                 modname = ef->strtab + dp->d_un.d_val;
  983                 error = linker_load_module(modname, lf);
  984                 if (error != 0)
  985                         goto out;
  986     }
  987 #endif
  988         error = relocate_file(ef);
  989         if (error != 0)
  990                 goto out;
  991 
  992         /*
  993          * Try and load the symbol table if it's present.  (you can
  994          * strip it!)
  995          */
  996         nbytes = hdr->e_shnum * hdr->e_shentsize;
  997         if (nbytes == 0 || hdr->e_shoff == 0)
  998                 goto nosyms;
  999         shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
 1000         error = vn_rdwr(UIO_READ, nd.ni_vp,
 1001             (caddr_t)shdr, nbytes, hdr->e_shoff,
 1002             UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
 1003             &resid, td);
 1004         if (error != 0)
 1005                 goto out;
 1006         symtabindex = -1;
 1007         symstrindex = -1;
 1008         for (i = 0; i < hdr->e_shnum; i++) {
 1009                 if (shdr[i].sh_type == SHT_SYMTAB) {
 1010                         symtabindex = i;
 1011                         symstrindex = shdr[i].sh_link;
 1012                 }
 1013         }
 1014         if (symtabindex < 0 || symstrindex < 0)
 1015                 goto nosyms;
 1016 
 1017         symcnt = shdr[symtabindex].sh_size;
 1018         ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK);
 1019         strcnt = shdr[symstrindex].sh_size;
 1020         ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK);
 1021 
 1022         error = vn_rdwr(UIO_READ, nd.ni_vp,
 1023             ef->symbase, symcnt, shdr[symtabindex].sh_offset,
 1024             UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
 1025             &resid, td);
 1026         if (error != 0)
 1027                 goto out;
 1028         error = vn_rdwr(UIO_READ, nd.ni_vp,
 1029             ef->strbase, strcnt, shdr[symstrindex].sh_offset,
 1030             UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
 1031             &resid, td);
 1032         if (error != 0)
 1033                 goto out;
 1034 
 1035         ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
 1036         ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
 1037         ef->ddbstrcnt = strcnt;
 1038         ef->ddbstrtab = ef->strbase;
 1039 
 1040 nosyms:
 1041         error = link_elf_link_common_finish(lf);
 1042         if (error != 0)
 1043                 goto out;
 1044 
 1045         *result = lf;
 1046 
 1047 out:
 1048         VOP_UNLOCK(nd.ni_vp, 0);
 1049         vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
 1050         VFS_UNLOCK_GIANT(vfslocked);
 1051         if (error != 0 && lf != NULL)
 1052                 linker_file_unload(lf, LINKER_UNLOAD_FORCE);
 1053         if (shdr != NULL)
 1054                 free(shdr, M_LINKER);
 1055         if (firstpage != NULL)
 1056                 free(firstpage, M_LINKER);
 1057 
 1058         return (error);
 1059 }
 1060 
 1061 Elf_Addr
 1062 elf_relocaddr(linker_file_t lf, Elf_Addr x)
 1063 {
 1064         elf_file_t ef;
 1065 
 1066         ef = (elf_file_t)lf;
 1067         if (x >= ef->pcpu_start && x < ef->pcpu_stop)
 1068                 return ((x - ef->pcpu_start) + ef->pcpu_base);
 1069 #ifdef VIMAGE
 1070         if (x >= ef->vnet_start && x < ef->vnet_stop)
 1071                 return ((x - ef->vnet_start) + ef->vnet_base);
 1072 #endif
 1073         return (x);
 1074 }
 1075 
 1076 
 1077 static void
 1078 link_elf_unload_file(linker_file_t file)
 1079 {
 1080         elf_file_t ef = (elf_file_t) file;
 1081 
 1082         if (ef->pcpu_base != 0) {
 1083                 dpcpu_free((void *)ef->pcpu_base,
 1084                     ef->pcpu_stop - ef->pcpu_start);
 1085                 elf_set_delete(&set_pcpu_list, ef->pcpu_start);
 1086         }
 1087 #ifdef VIMAGE
 1088         if (ef->vnet_base != 0) {
 1089                 vnet_data_free((void *)ef->vnet_base,
 1090                     ef->vnet_stop - ef->vnet_start);
 1091                 elf_set_delete(&set_vnet_list, ef->vnet_start);
 1092         }
 1093 #endif
 1094 #ifdef GDB
 1095         if (ef->gdb.l_ld != NULL) {
 1096                 GDB_STATE(RT_DELETE);
 1097                 free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER);
 1098                 link_elf_delete_gdb(&ef->gdb);
 1099                 GDB_STATE(RT_CONSISTENT);
 1100         }
 1101 #endif
 1102 
 1103         /* Notify MD code that a module is being unloaded. */
 1104         elf_cpu_unload_file(file);
 1105 
 1106         if (ef->preloaded) {
 1107                 link_elf_unload_preload(file);
 1108                 return;
 1109         }
 1110 
 1111 #ifdef SPARSE_MAPPING
 1112         if (ef->object != NULL) {
 1113                 vm_map_remove(kernel_map, (vm_offset_t) ef->address,
 1114                     (vm_offset_t) ef->address
 1115                     + (ef->object->size << PAGE_SHIFT));
 1116         }
 1117 #else
 1118         if (ef->address != NULL)
 1119                 free(ef->address, M_LINKER);
 1120 #endif
 1121         if (ef->symbase != NULL)
 1122                 free(ef->symbase, M_LINKER);
 1123         if (ef->strbase != NULL)
 1124                 free(ef->strbase, M_LINKER);
 1125         if (ef->ctftab != NULL)
 1126                 free(ef->ctftab, M_LINKER);
 1127         if (ef->ctfoff != NULL)
 1128                 free(ef->ctfoff, M_LINKER);
 1129         if (ef->typoff != NULL)
 1130                 free(ef->typoff, M_LINKER);
 1131 }
 1132 
 1133 static void
 1134 link_elf_unload_preload(linker_file_t file)
 1135 {
 1136         if (file->filename != NULL)
 1137                 preload_delete_name(file->filename);
 1138 }
 1139 
 1140 static const char *
 1141 symbol_name(elf_file_t ef, Elf_Size r_info)
 1142 {
 1143         const Elf_Sym *ref;
 1144 
 1145         if (ELF_R_SYM(r_info)) {
 1146                 ref = ef->symtab + ELF_R_SYM(r_info);
 1147                 return (ef->strtab + ref->st_name);
 1148         }
 1149         return (NULL);
 1150 }
 1151 
 1152 static int
 1153 relocate_file(elf_file_t ef)
 1154 {
 1155         const Elf_Rel *rellim;
 1156         const Elf_Rel *rel;
 1157         const Elf_Rela *relalim;
 1158         const Elf_Rela *rela;
 1159         const char *symname;
 1160 
 1161         /* Perform relocations without addend if there are any: */
 1162         rel = ef->rel;
 1163         if (rel != NULL) {
 1164                 rellim = (const Elf_Rel *)
 1165                     ((const char *)ef->rel + ef->relsize);
 1166                 while (rel < rellim) {
 1167                         if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel,
 1168                             ELF_RELOC_REL, elf_lookup)) {
 1169                                 symname = symbol_name(ef, rel->r_info);
 1170                                 printf("link_elf: symbol %s undefined\n", symname);
 1171                                 return (ENOENT);
 1172                         }
 1173                         rel++;
 1174                 }
 1175         }
 1176 
 1177         /* Perform relocations with addend if there are any: */
 1178         rela = ef->rela;
 1179         if (rela != NULL) {
 1180                 relalim = (const Elf_Rela *)
 1181                     ((const char *)ef->rela + ef->relasize);
 1182                 while (rela < relalim) {
 1183                         if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela,
 1184                             ELF_RELOC_RELA, elf_lookup)) {
 1185                                 symname = symbol_name(ef, rela->r_info);
 1186                                 printf("link_elf: symbol %s undefined\n",
 1187                                     symname);
 1188                                 return (ENOENT);
 1189                         }
 1190                         rela++;
 1191                 }
 1192         }
 1193 
 1194         /* Perform PLT relocations without addend if there are any: */
 1195         rel = ef->pltrel;
 1196         if (rel != NULL) {
 1197                 rellim = (const Elf_Rel *)
 1198                     ((const char *)ef->pltrel + ef->pltrelsize);
 1199                 while (rel < rellim) {
 1200                         if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel,
 1201                             ELF_RELOC_REL, elf_lookup)) {
 1202                                 symname = symbol_name(ef, rel->r_info);
 1203                                 printf("link_elf: symbol %s undefined\n",
 1204                                     symname);
 1205                                 return (ENOENT);
 1206                         }
 1207                         rel++;
 1208                 }
 1209         }
 1210 
 1211         /* Perform relocations with addend if there are any: */
 1212         rela = ef->pltrela;
 1213         if (rela != NULL) {
 1214                 relalim = (const Elf_Rela *)
 1215                     ((const char *)ef->pltrela + ef->pltrelasize);
 1216                 while (rela < relalim) {
 1217                         if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela,
 1218                             ELF_RELOC_RELA, elf_lookup)) {
 1219                                 symname = symbol_name(ef, rela->r_info);
 1220                                 printf("link_elf: symbol %s undefined\n",
 1221                                     symname);
 1222                                 return (ENOENT);
 1223                         }
 1224                         rela++;
 1225                 }
 1226         }
 1227 
 1228         return (0);
 1229 }
 1230 
 1231 /*
 1232  * Hash function for symbol table lookup.  Don't even think about changing
 1233  * this.  It is specified by the System V ABI.
 1234  */
 1235 static unsigned long
 1236 elf_hash(const char *name)
 1237 {
 1238         const unsigned char *p = (const unsigned char *) name;
 1239         unsigned long h = 0;
 1240         unsigned long g;
 1241 
 1242         while (*p != '\0') {
 1243                 h = (h << 4) + *p++;
 1244                 if ((g = h & 0xf0000000) != 0)
 1245                         h ^= g >> 24;
 1246                 h &= ~g;
 1247         }
 1248         return (h);
 1249 }
 1250 
 1251 static int
 1252 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym)
 1253 {
 1254         elf_file_t ef = (elf_file_t) lf;
 1255         unsigned long symnum;
 1256         const Elf_Sym* symp;
 1257         const char *strp;
 1258         unsigned long hash;
 1259         int i;
 1260 
 1261         /* If we don't have a hash, bail. */
 1262         if (ef->buckets == NULL || ef->nbuckets == 0) {
 1263                 printf("link_elf_lookup_symbol: missing symbol hash table\n");
 1264                 return (ENOENT);
 1265         }
 1266 
 1267         /* First, search hashed global symbols */
 1268         hash = elf_hash(name);
 1269         symnum = ef->buckets[hash % ef->nbuckets];
 1270 
 1271         while (symnum != STN_UNDEF) {
 1272                 if (symnum >= ef->nchains) {
 1273                         printf("%s: corrupt symbol table\n", __func__);
 1274                         return (ENOENT);
 1275                 }
 1276 
 1277                 symp = ef->symtab + symnum;
 1278                 if (symp->st_name == 0) {
 1279                         printf("%s: corrupt symbol table\n", __func__);
 1280                         return (ENOENT);
 1281                 }
 1282 
 1283                 strp = ef->strtab + symp->st_name;
 1284 
 1285                 if (strcmp(name, strp) == 0) {
 1286                         if (symp->st_shndx != SHN_UNDEF ||
 1287                             (symp->st_value != 0 &&
 1288                              ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
 1289                                 *sym = (c_linker_sym_t) symp;
 1290                                 return (0);
 1291                         }
 1292                         return (ENOENT);
 1293                 }
 1294 
 1295                 symnum = ef->chains[symnum];
 1296         }
 1297 
 1298         /* If we have not found it, look at the full table (if loaded) */
 1299         if (ef->symtab == ef->ddbsymtab)
 1300                 return (ENOENT);
 1301 
 1302         /* Exhaustive search */
 1303         for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
 1304                 strp = ef->ddbstrtab + symp->st_name;
 1305                 if (strcmp(name, strp) == 0) {
 1306                         if (symp->st_shndx != SHN_UNDEF ||
 1307                             (symp->st_value != 0 &&
 1308                              ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
 1309                                 *sym = (c_linker_sym_t) symp;
 1310                                 return (0);
 1311                         }
 1312                         return (ENOENT);
 1313                 }
 1314         }
 1315 
 1316         return (ENOENT);
 1317 }
 1318 
 1319 static int
 1320 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym,
 1321     linker_symval_t *symval)
 1322 {
 1323         elf_file_t ef = (elf_file_t) lf;
 1324         const Elf_Sym* es = (const Elf_Sym*) sym;
 1325 
 1326         if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) {
 1327                 symval->name = ef->strtab + es->st_name;
 1328                 symval->value = (caddr_t) ef->address + es->st_value;
 1329                 symval->size = es->st_size;
 1330                 return (0);
 1331         }
 1332         if (ef->symtab == ef->ddbsymtab)
 1333                 return (ENOENT);
 1334         if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
 1335                 symval->name = ef->ddbstrtab + es->st_name;
 1336                 symval->value = (caddr_t) ef->address + es->st_value;
 1337                 symval->size = es->st_size;
 1338                 return (0);
 1339         }
 1340         return (ENOENT);
 1341 }
 1342 
 1343 static int
 1344 link_elf_search_symbol(linker_file_t lf, caddr_t value,
 1345     c_linker_sym_t *sym, long *diffp)
 1346 {
 1347         elf_file_t ef = (elf_file_t) lf;
 1348         u_long off = (uintptr_t) (void *) value;
 1349         u_long diff = off;
 1350         u_long st_value;
 1351         const Elf_Sym* es;
 1352         const Elf_Sym* best = 0;
 1353         int i;
 1354 
 1355         for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
 1356                 if (es->st_name == 0)
 1357                         continue;
 1358                 st_value = es->st_value + (uintptr_t) (void *) ef->address;
 1359                 if (off >= st_value) {
 1360                         if (off - st_value < diff) {
 1361                                 diff = off - st_value;
 1362                                 best = es;
 1363                                 if (diff == 0)
 1364                                         break;
 1365                         } else if (off - st_value == diff) {
 1366                                 best = es;
 1367                         }
 1368                 }
 1369         }
 1370         if (best == 0)
 1371                 *diffp = off;
 1372         else
 1373                 *diffp = diff;
 1374         *sym = (c_linker_sym_t) best;
 1375 
 1376         return (0);
 1377 }
 1378 
 1379 /*
 1380  * Look up a linker set on an ELF system.
 1381  */
 1382 static int
 1383 link_elf_lookup_set(linker_file_t lf, const char *name,
 1384     void ***startp, void ***stopp, int *countp)
 1385 {
 1386         c_linker_sym_t sym;
 1387         linker_symval_t symval;
 1388         char *setsym;
 1389         void **start, **stop;
 1390         int len, error = 0, count;
 1391 
 1392         len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
 1393         setsym = malloc(len, M_LINKER, M_WAITOK);
 1394 
 1395         /* get address of first entry */
 1396         snprintf(setsym, len, "%s%s", "__start_set_", name);
 1397         error = link_elf_lookup_symbol(lf, setsym, &sym);
 1398         if (error != 0)
 1399                 goto out;
 1400         link_elf_symbol_values(lf, sym, &symval);
 1401         if (symval.value == 0) {
 1402                 error = ESRCH;
 1403                 goto out;
 1404         }
 1405         start = (void **)symval.value;
 1406 
 1407         /* get address of last entry */
 1408         snprintf(setsym, len, "%s%s", "__stop_set_", name);
 1409         error = link_elf_lookup_symbol(lf, setsym, &sym);
 1410         if (error != 0)
 1411                 goto out;
 1412         link_elf_symbol_values(lf, sym, &symval);
 1413         if (symval.value == 0) {
 1414                 error = ESRCH;
 1415                 goto out;
 1416         }
 1417         stop = (void **)symval.value;
 1418 
 1419         /* and the number of entries */
 1420         count = stop - start;
 1421 
 1422         /* and copy out */
 1423         if (startp != NULL)
 1424                 *startp = start;
 1425         if (stopp != NULL)
 1426                 *stopp = stop;
 1427         if (countp != NULL)
 1428                 *countp = count;
 1429 
 1430 out:
 1431         free(setsym, M_LINKER);
 1432         return (error);
 1433 }
 1434 
 1435 static int
 1436 link_elf_each_function_name(linker_file_t file,
 1437   int (*callback)(const char *, void *), void *opaque)
 1438 {
 1439         elf_file_t ef = (elf_file_t)file;
 1440         const Elf_Sym *symp;
 1441         int i, error;
 1442 
 1443         /* Exhaustive search */
 1444         for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
 1445                 if (symp->st_value != 0 &&
 1446                     ELF_ST_TYPE(symp->st_info) == STT_FUNC) {
 1447                         error = callback(ef->ddbstrtab + symp->st_name, opaque);
 1448                         if (error != 0)
 1449                                 return (error);
 1450                 }
 1451         }
 1452         return (0);
 1453 }
 1454 
 1455 static int
 1456 link_elf_each_function_nameval(linker_file_t file,
 1457     linker_function_nameval_callback_t callback, void *opaque)
 1458 {
 1459         linker_symval_t symval;
 1460         elf_file_t ef = (elf_file_t)file;
 1461         const Elf_Sym* symp;
 1462         int i, error;
 1463 
 1464         /* Exhaustive search */
 1465         for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
 1466                 if (symp->st_value != 0 &&
 1467                     ELF_ST_TYPE(symp->st_info) == STT_FUNC) {
 1468                         error = link_elf_symbol_values(file,
 1469                             (c_linker_sym_t) symp, &symval);
 1470                         if (error != 0)
 1471                                 return (error);
 1472                         error = callback(file, i, &symval, opaque);
 1473                         if (error != 0)
 1474                                 return (error);
 1475                 }
 1476         }
 1477         return (0);
 1478 }
 1479 
 1480 #ifdef __ia64__
 1481 /*
 1482  * Each KLD has its own GP. The GP value for each load module is given by
 1483  * DT_PLTGOT on ia64. We need GP to construct function descriptors, but
 1484  * don't have direct access to the ELF file structure. The link_elf_get_gp()
 1485  * function returns the GP given a pointer to a generic linker file struct.
 1486  */
 1487 Elf_Addr
 1488 link_elf_get_gp(linker_file_t lf)
 1489 {
 1490         elf_file_t ef = (elf_file_t)lf;
 1491         return ((Elf_Addr)ef->got);
 1492 }
 1493 #endif
 1494 
 1495 const Elf_Sym *
 1496 elf_get_sym(linker_file_t lf, Elf_Size symidx)
 1497 {
 1498         elf_file_t ef = (elf_file_t)lf;
 1499 
 1500         if (symidx >= ef->nchains)
 1501                 return (NULL);
 1502         return (ef->symtab + symidx);
 1503 }
 1504 
 1505 const char *
 1506 elf_get_symname(linker_file_t lf, Elf_Size symidx)
 1507 {
 1508         elf_file_t ef = (elf_file_t)lf;
 1509         const Elf_Sym *sym;
 1510 
 1511         if (symidx >= ef->nchains)
 1512                 return (NULL);
 1513         sym = ef->symtab + symidx;
 1514         return (ef->strtab + sym->st_name);
 1515 }
 1516 
 1517 /*
 1518  * Symbol lookup function that can be used when the symbol index is known (ie
 1519  * in relocations). It uses the symbol index instead of doing a fully fledged
 1520  * hash table based lookup when such is valid. For example for local symbols.
 1521  * This is not only more efficient, it's also more correct. It's not always
 1522  * the case that the symbol can be found through the hash table.
 1523  */
 1524 static Elf_Addr
 1525 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps)
 1526 {
 1527         elf_file_t ef = (elf_file_t)lf;
 1528         const Elf_Sym *sym;
 1529         const char *symbol;
 1530         Elf_Addr addr, start, base;
 1531 
 1532         /* Don't even try to lookup the symbol if the index is bogus. */
 1533         if (symidx >= ef->nchains)
 1534                 return (0);
 1535 
 1536         sym = ef->symtab + symidx;
 1537 
 1538         /*
 1539          * Don't do a full lookup when the symbol is local. It may even
 1540          * fail because it may not be found through the hash table.
 1541          */
 1542         if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
 1543                 /* Force lookup failure when we have an insanity. */
 1544                 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0)
 1545                         return (0);
 1546                 return ((Elf_Addr)ef->address + sym->st_value);
 1547         }
 1548 
 1549         /*
 1550          * XXX we can avoid doing a hash table based lookup for global
 1551          * symbols as well. This however is not always valid, so we'll
 1552          * just do it the hard way for now. Performance tweaks can
 1553          * always be added.
 1554          */
 1555 
 1556         symbol = ef->strtab + sym->st_name;
 1557 
 1558         /* Force a lookup failure if the symbol name is bogus. */
 1559         if (*symbol == 0)
 1560                 return (0);
 1561 
 1562         addr = ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
 1563 
 1564         if (elf_set_find(&set_pcpu_list, addr, &start, &base))
 1565                 addr = addr - start + base;
 1566 #ifdef VIMAGE
 1567         else if (elf_set_find(&set_vnet_list, addr, &start, &base))
 1568                 addr = addr - start + base;
 1569 #endif
 1570         return addr;
 1571 }
 1572 
 1573 static void
 1574 link_elf_reloc_local(linker_file_t lf)
 1575 {
 1576         const Elf_Rel *rellim;
 1577         const Elf_Rel *rel;
 1578         const Elf_Rela *relalim;
 1579         const Elf_Rela *rela;
 1580         elf_file_t ef = (elf_file_t)lf;
 1581 
 1582         /* Perform relocations without addend if there are any: */
 1583         if ((rel = ef->rel) != NULL) {
 1584                 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
 1585                 while (rel < rellim) {
 1586                         elf_reloc_local(lf, (Elf_Addr)ef->address, rel,
 1587                             ELF_RELOC_REL, elf_lookup);
 1588                         rel++;
 1589                 }
 1590         }
 1591 
 1592         /* Perform relocations with addend if there are any: */
 1593         if ((rela = ef->rela) != NULL) {
 1594                 relalim = (const Elf_Rela *)
 1595                     ((const char *)ef->rela + ef->relasize);
 1596                 while (rela < relalim) {
 1597                         elf_reloc_local(lf, (Elf_Addr)ef->address, rela,
 1598                             ELF_RELOC_RELA, elf_lookup);
 1599                         rela++;
 1600                 }
 1601         }
 1602 }
 1603 
 1604 static long
 1605 link_elf_symtab_get(linker_file_t lf, const Elf_Sym **symtab)
 1606 {
 1607         elf_file_t ef = (elf_file_t)lf;
 1608 
 1609         *symtab = ef->ddbsymtab;
 1610 
 1611         if (*symtab == NULL)
 1612                 return (0);
 1613 
 1614         return (ef->ddbsymcnt);
 1615 }
 1616 
 1617 static long
 1618 link_elf_strtab_get(linker_file_t lf, caddr_t *strtab)
 1619 {
 1620         elf_file_t ef = (elf_file_t)lf;
 1621 
 1622         *strtab = ef->ddbstrtab;
 1623 
 1624         if (*strtab == NULL)
 1625                 return (0);
 1626 
 1627         return (ef->ddbstrcnt);
 1628 }

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