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

     /*-
      * Copyright (c) 1998-2000 Doug Rabson
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD: releng/5.1/sys/kern/link_elf.c 114946 2003-05-12 15:08:10Z phk $
     */
    
    #include "opt_ddb.h"
    #include "opt_mac.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/mac.h>
    #include <sys/malloc.h>
    #include <sys/mutex.h>
    #include <sys/proc.h>
    #include <sys/namei.h>
    #include <sys/fcntl.h>
    #include <sys/vnode.h>
    #include <sys/linker.h>
    
    #include <machine/elf.h>
    #ifdef GPROF
    #include <machine/profile.h>
    #endif
    
    #include <vm/vm.h>
    #include <vm/vm_param.h>
    #ifdef SPARSE_MAPPING
    #include <vm/vm_object.h>
    #include <vm/vm_kern.h>
    #include <vm/vm_extern.h>
    #endif
    #include <vm/pmap.h>
    #include <vm/vm_map.h>
    
    #include <sys/link_elf.h>
    
    #include "linker_if.h"
    
    typedef struct elf_file {
        struct linker_file  lf;             /* Common fields */
        int                 preloaded;      /* Was file pre-loaded */
        caddr_t             address;        /* Relocation address */
    #ifdef SPARSE_MAPPING
        vm_object_t         object;         /* VM object to hold file pages */
    #endif
        Elf_Dyn*            dynamic;        /* Symbol table etc. */
        Elf_Hashelt         nbuckets;       /* DT_HASH info */
        Elf_Hashelt         nchains;
        const Elf_Hashelt*  buckets;
        const Elf_Hashelt*  chains;
        caddr_t             hash;
        caddr_t             strtab;         /* DT_STRTAB */
        int                 strsz;          /* DT_STRSZ */
        const Elf_Sym*      symtab;         /* DT_SYMTAB */
        Elf_Addr*           got;            /* DT_PLTGOT */
        const Elf_Rel*      pltrel;         /* DT_JMPREL */
        int                 pltrelsize;     /* DT_PLTRELSZ */
        const Elf_Rela*     pltrela;        /* DT_JMPREL */
        int                 pltrelasize;    /* DT_PLTRELSZ */
        const Elf_Rel*      rel;            /* DT_REL */
        int                 relsize;        /* DT_RELSZ */
        const Elf_Rela*     rela;           /* DT_RELA */
        int                 relasize;       /* DT_RELASZ */
        caddr_t             modptr;
        const Elf_Sym*      ddbsymtab;      /* The symbol table we are using */
        long                ddbsymcnt;      /* Number of symbols */
        caddr_t             ddbstrtab;      /* String table */
        long                ddbstrcnt;      /* number of bytes in string table */
        caddr_t             symbase;        /* malloc'ed symbold base */
        caddr_t             strbase;        /* malloc'ed string base */
    #ifdef DDB
        struct link_map     gdb;            /* hooks for gdb */
    #endif
    } *elf_file_t;
   
   static int      link_elf_link_common_finish(linker_file_t);
   static int      link_elf_link_preload(linker_class_t cls,
                                         const char*, linker_file_t*);
   static int      link_elf_link_preload_finish(linker_file_t);
   static int      link_elf_load_file(linker_class_t, const char*, linker_file_t*);
   static int      link_elf_lookup_symbol(linker_file_t, const char*,
                                          c_linker_sym_t*);
   static int      link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*);
   static int      link_elf_search_symbol(linker_file_t, caddr_t value,
                                          c_linker_sym_t* sym, long* diffp);
   
   static void     link_elf_unload_file(linker_file_t);
   static void     link_elf_unload_preload(linker_file_t);
   static int      link_elf_lookup_set(linker_file_t, const char *,
                                       void ***, void ***, int *);
   static int      link_elf_each_function_name(linker_file_t,
                                   int (*)(const char *, void *),
                                   void *);
   static void     link_elf_reloc_local(linker_file_t);
   
   static kobj_method_t link_elf_methods[] = {
       KOBJMETHOD(linker_lookup_symbol,    link_elf_lookup_symbol),
       KOBJMETHOD(linker_symbol_values,    link_elf_symbol_values),
       KOBJMETHOD(linker_search_symbol,    link_elf_search_symbol),
       KOBJMETHOD(linker_unload,           link_elf_unload_file),
       KOBJMETHOD(linker_load_file,        link_elf_load_file),
       KOBJMETHOD(linker_link_preload,     link_elf_link_preload),
       KOBJMETHOD(linker_link_preload_finish, link_elf_link_preload_finish),
       KOBJMETHOD(linker_lookup_set,       link_elf_lookup_set),
       KOBJMETHOD(linker_each_function_name, link_elf_each_function_name),
       { 0, 0 }
   };
   
   static struct linker_class link_elf_class = {
   #if ELF_TARG_CLASS == ELFCLASS32
       "elf32",
   #else
       "elf64",
   #endif
       link_elf_methods, sizeof(struct elf_file)
   };
   
   static int              parse_dynamic(elf_file_t ef);
   static int              relocate_file(elf_file_t ef);
   static int              link_elf_preload_parse_symbols(elf_file_t ef);
   
   #ifdef DDB
   static void             r_debug_state(struct r_debug *dummy_one,
                                         struct link_map *dummy_two);
   
   /*
    * A list of loaded modules for GDB to use for loading symbols.
    */
   struct r_debug r_debug;
   
   #define GDB_STATE(s)    r_debug.r_state = s; r_debug_state(NULL, NULL);
   
   /*
    * Function for the debugger to set a breakpoint on to gain control.
    */
   static void
   r_debug_state(struct r_debug *dummy_one __unused,
                 struct link_map *dummy_two __unused)
   {
   }
   
   static void
   link_elf_add_gdb(struct link_map *l)
   {
       struct link_map *prev;
   
       l->l_next = NULL;
   
       if (r_debug.r_map == NULL) {
           /* Add first. */
           l->l_prev = NULL;
           r_debug.r_map = l;
       } else {
           /* Append to list. */
           for (prev = r_debug.r_map; prev->l_next != NULL; prev = prev->l_next)
               ;
           l->l_prev = prev;
           prev->l_next = l;
       }
   }
   
   static void
   link_elf_delete_gdb(struct link_map *l)
   {
       if (l->l_prev == NULL) {
           /* Remove first. */
           if ((r_debug.r_map = l->l_next) != NULL)
               l->l_next->l_prev = NULL;
       } else {
           /* Remove any but first. */
           if ((l->l_prev->l_next = l->l_next) != NULL)
               l->l_next->l_prev = l->l_prev;
       }
   }
   #endif /* DDB */
   
   #ifdef __ia64__
   Elf_Addr link_elf_get_gp(linker_file_t);
   #endif
   
   /*
    * The kernel symbol table starts here.
    */
   extern struct _dynamic _DYNAMIC;
   
   static void
   link_elf_error(const char *s)
   {
       printf("kldload: %s\n", s);
   }
   
   /*
    * Actions performed after linking/loading both the preloaded kernel and any
    * modules; whether preloaded or dynamicly loaded.
    */
   static int
   link_elf_link_common_finish(linker_file_t lf)
   {
   #ifdef DDB
       elf_file_t ef = (elf_file_t)lf;
       char *newfilename;
   #endif
       int error;
   
       /* Notify MD code that a module is being loaded. */
       error = elf_cpu_load_file(lf);
       if (error)
           return (error);
   
   #ifdef DDB
       GDB_STATE(RT_ADD);
       ef->gdb.l_addr = lf->address;
       newfilename = malloc(strlen(lf->filename) + 1, M_LINKER, M_WAITOK);
       strcpy(newfilename, lf->filename);
       ef->gdb.l_name = newfilename;
       ef->gdb.l_ld = ef->dynamic;
       link_elf_add_gdb(&ef->gdb);
       GDB_STATE(RT_CONSISTENT);
   #endif
   
       return (0);
   }
   
   static void
   link_elf_init(void* arg)
   {
       Elf_Dyn     *dp;
       caddr_t     modptr, baseptr, sizeptr;
       elf_file_t  ef;
       char        *modname;
   
       linker_add_class(&link_elf_class);
   
       dp = (Elf_Dyn*) &_DYNAMIC;
       modname = NULL;
       modptr = preload_search_by_type("elf" __XSTRING(__ELF_WORD_SIZE) " kernel");
       if (modptr == NULL)
           modptr = preload_search_by_type("elf kernel");
       if (modptr)
           modname = (char *)preload_search_info(modptr, MODINFO_NAME);
       if (modname == NULL)
           modname = "kernel";
       linker_kernel_file = linker_make_file(modname, &link_elf_class);
       if (linker_kernel_file == NULL)
           panic("link_elf_init: Can't create linker structures for kernel");
   
       ef = (elf_file_t) linker_kernel_file;
       ef->preloaded = 1;
       ef->address = 0;
   #ifdef SPARSE_MAPPING
       ef->object = 0;
   #endif
       ef->dynamic = dp;
   
       if (dp)
           parse_dynamic(ef);
       linker_kernel_file->address = (caddr_t) KERNBASE;
       linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;
   
       if (modptr) {
           ef->modptr = modptr;
           baseptr = preload_search_info(modptr, MODINFO_ADDR);
           if (baseptr)
               linker_kernel_file->address = *(caddr_t *)baseptr;
           sizeptr = preload_search_info(modptr, MODINFO_SIZE);
           if (sizeptr)
               linker_kernel_file->size = *(size_t *)sizeptr;
       }
       (void)link_elf_preload_parse_symbols(ef);
   
   #ifdef DDB
       r_debug.r_map = NULL;
       r_debug.r_brk = r_debug_state;
       r_debug.r_state = RT_CONSISTENT;
   #endif
   
       (void)link_elf_link_common_finish(linker_kernel_file);
   }
   
   SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0);
   
   static int
   link_elf_preload_parse_symbols(elf_file_t ef)
   {
       caddr_t     pointer;
       caddr_t     ssym, esym, base;
       caddr_t     strtab;
       int         strcnt;
       Elf_Sym*    symtab;
       int         symcnt;
   
       if (ef->modptr == NULL)
           return 0;
       pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM);
       if (pointer == NULL)
           return 0;
       ssym = *(caddr_t *)pointer;
       pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM);
       if (pointer == NULL)
           return 0;
       esym = *(caddr_t *)pointer;
   
       base = ssym;
   
       symcnt = *(long *)base;
       base += sizeof(long);
       symtab = (Elf_Sym *)base;
       base += roundup(symcnt, sizeof(long));
   
       if (base > esym || base < ssym) {
           printf("Symbols are corrupt!\n");
           return EINVAL;
       }
   
       strcnt = *(long *)base;
       base += sizeof(long);
       strtab = base;
       base += roundup(strcnt, sizeof(long));
   
       if (base > esym || base < ssym) {
           printf("Symbols are corrupt!\n");
           return EINVAL;
       }
   
       ef->ddbsymtab = symtab;
       ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
       ef->ddbstrtab = strtab;
       ef->ddbstrcnt = strcnt;
   
       return 0;
   }
   
   static int
   parse_dynamic(elf_file_t ef)
   {
       Elf_Dyn *dp;
       int plttype = DT_REL;
   
       for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
           switch (dp->d_tag) {
           case DT_HASH:
           {
               /* From src/libexec/rtld-elf/rtld.c */
               const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
                   (ef->address + dp->d_un.d_ptr);
               ef->nbuckets = hashtab[0];
               ef->nchains = hashtab[1];
               ef->buckets = hashtab + 2;
               ef->chains = ef->buckets + ef->nbuckets;
               break;
           }
           case DT_STRTAB:
               ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr);
               break;
           case DT_STRSZ:
               ef->strsz = dp->d_un.d_val;
               break;
           case DT_SYMTAB:
               ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr);
               break;
           case DT_SYMENT:
               if (dp->d_un.d_val != sizeof(Elf_Sym))
                   return ENOEXEC;
               break;
           case DT_PLTGOT:
               ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr);
               break;
           case DT_REL:
               ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
               break;
           case DT_RELSZ:
               ef->relsize = dp->d_un.d_val;
               break;
           case DT_RELENT:
               if (dp->d_un.d_val != sizeof(Elf_Rel))
                   return ENOEXEC;
               break;
           case DT_JMPREL:
               ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
               break;
           case DT_PLTRELSZ:
               ef->pltrelsize = dp->d_un.d_val;
               break;
           case DT_RELA:
               ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr);
               break;
           case DT_RELASZ:
               ef->relasize = dp->d_un.d_val;
               break;
           case DT_RELAENT:
               if (dp->d_un.d_val != sizeof(Elf_Rela))
                   return ENOEXEC;
               break;
           case DT_PLTREL:
               plttype = dp->d_un.d_val;
               if (plttype != DT_REL && plttype != DT_RELA)
                   return ENOEXEC;
               break;
   #ifdef DDB
           case DT_DEBUG:
               dp->d_un.d_ptr = (Elf_Addr) &r_debug;
               break;
   #endif
           }
       }
   
       if (plttype == DT_RELA) {
           ef->pltrela = (const Elf_Rela *) ef->pltrel;
           ef->pltrel = NULL;
           ef->pltrelasize = ef->pltrelsize;
           ef->pltrelsize = 0;
       }
   
       ef->ddbsymtab = ef->symtab;
       ef->ddbsymcnt = ef->nchains;
       ef->ddbstrtab = ef->strtab;
       ef->ddbstrcnt = ef->strsz;
   
       return 0;
   }
   
   static int
   link_elf_link_preload(linker_class_t cls,
                         const char* filename, linker_file_t *result)
   {
       caddr_t             modptr, baseptr, sizeptr, dynptr;
       char                *type;
       elf_file_t          ef;
       linker_file_t       lf;
       int                 error;
       vm_offset_t         dp;
   
       /* Look to see if we have the file preloaded */
       modptr = preload_search_by_name(filename);
       if (modptr == NULL)
           return ENOENT;
   
       type = (char *)preload_search_info(modptr, MODINFO_TYPE);
       baseptr = preload_search_info(modptr, MODINFO_ADDR);
       sizeptr = preload_search_info(modptr, MODINFO_SIZE);
       dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC);
       if (type == NULL ||
           (strcmp(type, "elf" __XSTRING(__ELF_WORD_SIZE) " module") != 0 &&
            strcmp(type, "elf module") != 0))
           return (EFTYPE);
       if (baseptr == NULL || sizeptr == NULL || dynptr == NULL)
           return (EINVAL);
   
       lf = linker_make_file(filename, &link_elf_class);
       if (lf == NULL) {
           return ENOMEM;
       }
   
       ef = (elf_file_t) lf;
       ef->preloaded = 1;
       ef->modptr = modptr;
       ef->address = *(caddr_t *)baseptr;
   #ifdef SPARSE_MAPPING
       ef->object = 0;
   #endif
       dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
       ef->dynamic = (Elf_Dyn *)dp;
       lf->address = ef->address;
       lf->size = *(size_t *)sizeptr;
   
       error = parse_dynamic(ef);
       if (error) {
           linker_file_unload(lf);
           return error;
       }
       link_elf_reloc_local(lf);
       *result = lf;
       return (0);
   }
   
   static int
   link_elf_link_preload_finish(linker_file_t lf)
   {
       elf_file_t          ef;
       int error;
   
       ef = (elf_file_t) lf;
   #if 0   /* this will be more trouble than it's worth for now */
       for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
           if (dp->d_tag != DT_NEEDED)
               continue;
           modname = ef->strtab + dp->d_un.d_val;
           error = linker_load_module(modname, lf);
           if (error)
               goto out;
       }
   #endif
       error = relocate_file(ef);
       if (error)
           return error;
       (void)link_elf_preload_parse_symbols(ef);
   
       return (link_elf_link_common_finish(lf));
   }
   
   static int
   link_elf_load_file(linker_class_t cls, const char* filename,
           linker_file_t* result)
   {
       struct nameidata nd;
       struct thread* td = curthread;      /* XXX */
       Elf_Ehdr *hdr;
       caddr_t firstpage;
       int nbytes, i;
       Elf_Phdr *phdr;
       Elf_Phdr *phlimit;
       Elf_Phdr *segs[2];
       int nsegs;
       Elf_Phdr *phdyn;
       Elf_Phdr *phphdr;
       caddr_t mapbase;
       size_t mapsize;
       Elf_Off base_offset;
       Elf_Addr base_vaddr;
       Elf_Addr base_vlimit;
       int error = 0;
       int resid, flags;
       elf_file_t ef;
       linker_file_t lf;
       Elf_Shdr *shdr;
       int symtabindex;
       int symstrindex;
       int symcnt;
       int strcnt;
   
       GIANT_REQUIRED;
   
       shdr = NULL;
       lf = NULL;
   
       NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, td);
       flags = FREAD;
       error = vn_open(&nd, &flags, 0);
       if (error)
           return error;
       NDFREE(&nd, NDF_ONLY_PNBUF);
   #ifdef MAC
       error = mac_check_kld_load(curthread->td_ucred, nd.ni_vp);
       if (error) {
           firstpage = NULL;
           goto out;
       }
   #endif
   
       /*
        * Read the elf header from the file.
        */
       firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK);
       if (firstpage == NULL) {
           error = ENOMEM;
           goto out;
       }
       hdr = (Elf_Ehdr *)firstpage;
       error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0,
                       UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
                       &resid, td);
       nbytes = PAGE_SIZE - resid;
       if (error)
           goto out;
   
       if (!IS_ELF(*hdr)) {
           error = ENOEXEC;
           goto out;
       }
   
       if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS
         || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
           link_elf_error("Unsupported file layout");
           error = ENOEXEC;
           goto out;
       }
       if (hdr->e_ident[EI_VERSION] != EV_CURRENT
         || hdr->e_version != EV_CURRENT) {
           link_elf_error("Unsupported file version");
           error = ENOEXEC;
           goto out;
       }
       if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
           link_elf_error("Unsupported file type");
           error = ENOEXEC;
           goto out;
       }
       if (hdr->e_machine != ELF_TARG_MACH) {
           link_elf_error("Unsupported machine");
           error = ENOEXEC;
           goto out;
       }
   
       /*
        * We rely on the program header being in the first page.  This is
        * not strictly required by the ABI specification, but it seems to
        * always true in practice.  And, it simplifies things considerably.
        */
       if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
             (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
             (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
           link_elf_error("Unreadable program headers");
   
       /*
        * Scan the program header entries, and save key information.
        *
        * We rely on there being exactly two load segments, text and data,
        * in that order.
        */
       phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
       phlimit = phdr + hdr->e_phnum;
       nsegs = 0;
       phdyn = NULL;
       phphdr = NULL;
       while (phdr < phlimit) {
           switch (phdr->p_type) {
   
           case PT_LOAD:
               if (nsegs == 2) {
                   link_elf_error("Too many sections");
                   error = ENOEXEC;
                   goto out;
               }
               /*
                * XXX: We just trust they come in right order ??
                */
               segs[nsegs] = phdr;
               ++nsegs;
               break;
   
           case PT_PHDR:
               phphdr = phdr;
               break;
   
           case PT_DYNAMIC:
               phdyn = phdr;
               break;
   
           case PT_INTERP:
               link_elf_error("Unsupported file type");
               error = ENOEXEC;
               goto out;
           }
   
           ++phdr;
       }
       if (phdyn == NULL) {
           link_elf_error("Object is not dynamically-linked");
           error = ENOEXEC;
           goto out;
       }
       if (nsegs != 2) {
           link_elf_error("Too few sections");
           error = ENOEXEC;
           goto out;
       }
   
       /*
        * Allocate the entire address space of the object, to stake out our
        * contiguous region, and to establish the base address for relocation.
        */
       base_offset = trunc_page(segs[0]->p_offset);
       base_vaddr = trunc_page(segs[0]->p_vaddr);
       base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz);
       mapsize = base_vlimit - base_vaddr;
   
       lf = linker_make_file(filename, &link_elf_class);
       if (!lf) {
           error = ENOMEM;
           goto out;
       }
   
       ef = (elf_file_t) lf;
   #ifdef SPARSE_MAPPING
       ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
       if (ef->object == NULL) {
           error = ENOMEM;
           goto out;
       }
       vm_object_reference(ef->object);
       ef->address = (caddr_t) vm_map_min(kernel_map);
       error = vm_map_find(kernel_map, ef->object, 0,
                           (vm_offset_t *) &ef->address,
                           mapsize, 1,
                           VM_PROT_ALL, VM_PROT_ALL, 0);
       if (error) {
           vm_object_deallocate(ef->object);
           ef->object = 0;
           goto out;
       }
   #else
       ef->address = malloc(mapsize, M_LINKER, M_WAITOK);
       if (!ef->address) {
           error = ENOMEM;
           goto out;
       }
   #endif
       mapbase = ef->address;
   
       /*
        * Read the text and data sections and zero the bss.
        */
       for (i = 0; i < 2; i++) {
           caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
           error = vn_rdwr(UIO_READ, nd.ni_vp,
                           segbase, segs[i]->p_filesz, segs[i]->p_offset,
                           UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
                           &resid, td);
           if (error) {
               goto out;
           }
           bzero(segbase + segs[i]->p_filesz,
                 segs[i]->p_memsz - segs[i]->p_filesz);
   
   #ifdef SPARSE_MAPPING
           /*
            * Wire down the pages
            */
           vm_map_wire(kernel_map,
                       (vm_offset_t) segbase,
                       (vm_offset_t) segbase + segs[i]->p_memsz,
                       FALSE);
   #endif
       }
   
   #ifdef GPROF
       /* Update profiling information with the new text segment. */
       kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr +
           segs[0]->p_memsz));
   #endif
   
       ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
   
       lf->address = ef->address;
       lf->size = mapsize;
   
       error = parse_dynamic(ef);
       if (error)
           goto out;
       link_elf_reloc_local(lf);
   
       error = linker_load_dependencies(lf);
       if (error)
           goto out;
   #if 0   /* this will be more trouble than it's worth for now */
       for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
           if (dp->d_tag != DT_NEEDED)
               continue;
           modname = ef->strtab + dp->d_un.d_val;
           error = linker_load_module(modname, lf);
           if (error)
               goto out;
       }
   #endif
       error = relocate_file(ef);
       if (error)
           goto out;
   
       /* Try and load the symbol table if it's present.  (you can strip it!) */
       nbytes = hdr->e_shnum * hdr->e_shentsize;
       if (nbytes == 0 || hdr->e_shoff == 0)
           goto nosyms;
       shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
       if (shdr == NULL) {
           error = ENOMEM;
           goto out;
       }
       error = vn_rdwr(UIO_READ, nd.ni_vp,
                       (caddr_t)shdr, nbytes, hdr->e_shoff,
                       UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
                       &resid, td);
       if (error)
           goto out;
       symtabindex = -1;
       symstrindex = -1;
       for (i = 0; i < hdr->e_shnum; i++) {
           if (shdr[i].sh_type == SHT_SYMTAB) {
               symtabindex = i;
               symstrindex = shdr[i].sh_link;
           }
       }
       if (symtabindex < 0 || symstrindex < 0)
           goto nosyms;
   
       symcnt = shdr[symtabindex].sh_size;
       ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK);
       strcnt = shdr[symstrindex].sh_size;
       ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK);
   
       if (ef->symbase == NULL || ef->strbase == NULL) {
           error = ENOMEM;
           goto out;
       }
       error = vn_rdwr(UIO_READ, nd.ni_vp,
                       ef->symbase, symcnt, shdr[symtabindex].sh_offset,
                       UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
                       &resid, td);
       if (error)
           goto out;
       error = vn_rdwr(UIO_READ, nd.ni_vp,
                       ef->strbase, strcnt, shdr[symstrindex].sh_offset,
                       UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
                       &resid, td);
       if (error)
           goto out;
   
       ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
       ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
       ef->ddbstrcnt = strcnt;
       ef->ddbstrtab = ef->strbase;
   
       error = link_elf_link_common_finish(lf);
       if (error)
           goto out;
   
   nosyms:
   
       *result = lf;
   
   out:
       if (error && lf)
           linker_file_unload(lf);
       if (shdr)
           free(shdr, M_LINKER);
       if (firstpage)
           free(firstpage, M_LINKER);
       VOP_UNLOCK(nd.ni_vp, 0, td);
       vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
   
       return error;
   }
   
   static void
   link_elf_unload_file(linker_file_t file)
   {
       elf_file_t ef = (elf_file_t) file;
   
   #ifdef DDB
       if (ef->gdb.l_ld) {
           GDB_STATE(RT_DELETE);
           free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER);
           link_elf_delete_gdb(&ef->gdb);
           GDB_STATE(RT_CONSISTENT);
       }
   #endif
   
       /* Notify MD code that a module is being unloaded. */
       elf_cpu_unload_file(file);
   
       if (ef->preloaded) {
           link_elf_unload_preload(file);
           return;
       }
   
   #ifdef SPARSE_MAPPING
       if (ef->object) {
           vm_map_remove(kernel_map, (vm_offset_t) ef->address,
                         (vm_offset_t) ef->address
                         + (ef->object->size << PAGE_SHIFT));
           vm_object_deallocate(ef->object);
       }
   #else
       if (ef->address)
           free(ef->address, M_LINKER);
   #endif
       if (ef->symbase)
           free(ef->symbase, M_LINKER);
       if (ef->strbase)
           free(ef->strbase, M_LINKER);
   }
   
   static void
   link_elf_unload_preload(linker_file_t file)
   {
       if (file->filename)
           preload_delete_name(file->filename);
   }
   
   static const char *
   symbol_name(elf_file_t ef, Elf_Word r_info)
   {
       const Elf_Sym *ref;
   
       if (ELF_R_SYM(r_info)) {
           ref = ef->symtab + ELF_R_SYM(r_info);
           return ef->strtab + ref->st_name;
       } else
           return NULL;
   }
   
   static int
   relocate_file(elf_file_t ef)
   {
       const Elf_Rel *rellim;
       const Elf_Rel *rel;
       const Elf_Rela *relalim;
       const Elf_Rela *rela;
       const char *symname;
   
       /* Perform relocations without addend if there are any: */
       rel = ef->rel;
       if (rel) {
           rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
           while (rel < rellim) {
               if (elf_reloc(&ef->lf, rel, ELF_RELOC_REL)) {
                   symname = symbol_name(ef, rel->r_info);
                   printf("link_elf: symbol %s undefined\n", symname);
                   return ENOENT;
               }
               rel++;
           }
       }
   
       /* Perform relocations with addend if there are any: */
       rela = ef->rela;
       if (rela) {
           relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
           while (rela < relalim) {
               if (elf_reloc(&ef->lf, rela, ELF_RELOC_RELA)) {
                   symname = symbol_name(ef, rela->r_info);
                   printf("link_elf: symbol %s undefined\n", symname);
                   return ENOENT;
               }
               rela++;
           }
       }
   
       /* Perform PLT relocations without addend if there are any: */
       rel = ef->pltrel;
       if (rel) {
           rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize);
           while (rel < rellim) {
               if (elf_reloc(&ef->lf, rel, ELF_RELOC_REL)) {
                   symname = symbol_name(ef, rel->r_info);
                   printf("link_elf: symbol %s undefined\n", symname);
                   return ENOENT;
               }
               rel++;
           }
       }
   
       /* Perform relocations with addend if there are any: */
       rela = ef->pltrela;
       if (rela) {
           relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize);
           while (rela < relalim) {
               if (elf_reloc(&ef->lf, rela, ELF_RELOC_RELA)) {
                   symname = symbol_name(ef, rela->r_info);
                   printf("link_elf: symbol %s undefined\n", symname);
                   return ENOENT;
               }
               rela++;
           }
       }
   
       return 0;
   }
   
   /*
    * Hash function for symbol table lookup.  Don't even think about changing
    * this.  It is specified by the System V ABI.
    */
   static unsigned long
   elf_hash(const char *name)
   {
       const unsigned char *p = (const unsigned char *) name;
       unsigned long h = 0;
       unsigned long g;
   
       while (*p != '\0') {
           h = (h << 4) + *p++;
           if ((g = h & 0xf0000000) != 0)
               h ^= g >> 24;
           h &= ~g;
      }
      return h;
  }
  
  static int
  link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym)
  {
      elf_file_t ef = (elf_file_t) lf;
      unsigned long symnum;
      const Elf_Sym* symp;
      const char *strp;
      unsigned long hash;
      int i;
  
      /* First, search hashed global symbols */
      hash = elf_hash(name);
      symnum = ef->buckets[hash % ef->nbuckets];
  
      while (symnum != STN_UNDEF) {
          if (symnum >= ef->nchains) {
              printf("link_elf_lookup_symbol: corrupt symbol table\n");
              return ENOENT;
          }
  
          symp = ef->symtab + symnum;
          if (symp->st_name == 0) {
              printf("link_elf_lookup_symbol: corrupt symbol table\n");
              return ENOENT;
          }
  
          strp = ef->strtab + symp->st_name;
  
          if (strcmp(name, strp) == 0) {
              if (symp->st_shndx != SHN_UNDEF ||
                  (symp->st_value != 0 &&
                   ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
                  *sym = (c_linker_sym_t) symp;
                  return 0;
              } else
                  return ENOENT;
          }
  
          symnum = ef->chains[symnum];
      }
  
      /* If we have not found it, look at the full table (if loaded) */
      if (ef->symtab == ef->ddbsymtab)
          return ENOENT;
  
      /* Exhaustive search */
      for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
          strp = ef->ddbstrtab + symp->st_name;
          if (strcmp(name, strp) == 0) {
              if (symp->st_shndx != SHN_UNDEF ||
                  (symp->st_value != 0 &&
                   ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
                  *sym = (c_linker_sym_t) symp;
                  return 0;
              } else
                  return ENOENT;
          }
      }
  
      return ENOENT;
  }
  
  static int
  link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval)
  {
          elf_file_t ef = (elf_file_t) lf;
          const Elf_Sym* es = (const Elf_Sym*) sym;
  
          if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) {
              symval->name = ef->strtab + es->st_name;
              symval->value = (caddr_t) ef->address + es->st_value;
              symval->size = es->st_size;
              return 0;
          }
          if (ef->symtab == ef->ddbsymtab)
              return ENOENT;
          if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
              symval->name = ef->ddbstrtab + es->st_name;
              symval->value = (caddr_t) ef->address + es->st_value;
              symval->size = es->st_size;
              return 0;
          }
          return ENOENT;
  }
  
  static int
  link_elf_search_symbol(linker_file_t lf, caddr_t value,
                         c_linker_sym_t* sym, long* diffp)
  {
          elf_file_t ef = (elf_file_t) lf;
          u_long off = (uintptr_t) (void *) value;
          u_long diff = off;
          u_long st_value;
          const Elf_Sym* es;
          const Elf_Sym* best = 0;
          int i;
  
          for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
                  if (es->st_name == 0)
                          continue;
                  st_value = es->st_value + (uintptr_t) (void *) ef->address;
                  if (off >= st_value) {
                          if (off - st_value < diff) {
                                  diff = off - st_value;
                                  best = es;
                                  if (diff == 0)
                                          break;
                          } else if (off - st_value == diff) {
                                  best = es;
                          }
                  }
          }
          if (best == 0)
                  *diffp = off;
          else
                  *diffp = diff;
          *sym = (c_linker_sym_t) best;
  
          return 0;
  }
  
  /*
   * Look up a linker set on an ELF system.
   */
  static int
  link_elf_lookup_set(linker_file_t lf, const char *name,
                      void ***startp, void ***stopp, int *countp)
  {
          c_linker_sym_t sym;
          linker_symval_t symval;
          char *setsym;
          void **start, **stop;
          int len, error = 0, count;
  
          len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
          setsym = malloc(len, M_LINKER, M_WAITOK);
          if (setsym == NULL)
                  return ENOMEM;
  
          /* get address of first entry */
          snprintf(setsym, len, "%s%s", "__start_set_", name);
          error = link_elf_lookup_symbol(lf, setsym, &sym);
          if (error)
                  goto out;
          link_elf_symbol_values(lf, sym, &symval);
          if (symval.value == 0) {
                  error = ESRCH;
                  goto out;
          }
          start = (void **)symval.value;
  
          /* get address of last entry */
          snprintf(setsym, len, "%s%s", "__stop_set_", name);
          error = link_elf_lookup_symbol(lf, setsym, &sym);
          if (error)
                  goto out;
          link_elf_symbol_values(lf, sym, &symval);
          if (symval.value == 0) {
                  error = ESRCH;
                  goto out;
          }
          stop = (void **)symval.value;
  
          /* and the number of entries */
          count = stop - start;
  
          /* and copy out */
          if (startp)
                  *startp = start;
          if (stopp)
                  *stopp = stop;
          if (countp)
                  *countp = count;
  
  out:
          free(setsym, M_LINKER);
          return error;
  }
  
  static int
  link_elf_each_function_name(linker_file_t file,
    int (*callback)(const char *, void *), void *opaque) {
      elf_file_t ef = (elf_file_t)file;
      const Elf_Sym* symp;
      int i, error;
          
      /* Exhaustive search */
      for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
          if (symp->st_value != 0 &&
              ELF_ST_TYPE(symp->st_info) == STT_FUNC) {
                  error = callback(ef->ddbstrtab + symp->st_name, opaque);
                  if (error)
                      return (error);
          }
      }
      return (0);
  }
  
  #ifdef __ia64__
  /*
   * Each KLD has its own GP. The GP value for each load module is given by
   * DT_PLTGOT on ia64. We need GP to construct function descriptors, but
   * don't have direct access to the ELF file structure. The link_elf_get_gp()
   * function returns the GP given a pointer to a generic linker file struct.
   */
  Elf_Addr
  link_elf_get_gp(linker_file_t lf)
  {
          elf_file_t ef = (elf_file_t)lf;
          return (Elf_Addr)ef->got;
  }
  #endif
  
  const Elf_Sym *
  elf_get_sym(linker_file_t lf, Elf_Word symidx)
  {
          elf_file_t ef = (elf_file_t)lf;
  
          if (symidx >= ef->nchains)
                  return (NULL);
          return (ef->symtab + symidx);
  }
  
  const char *
  elf_get_symname(linker_file_t lf, Elf_Word symidx)
  {
          elf_file_t ef = (elf_file_t)lf;
          const Elf_Sym *sym;
  
          if (symidx >= ef->nchains)
                  return (NULL);
          sym = ef->symtab + symidx;
          return (ef->strtab + sym->st_name);
  }
  
  /*
   * Symbol lookup function that can be used when the symbol index is known (ie
   * in relocations). It uses the symbol index instead of doing a fully fledged
   * hash table based lookup when such is valid. For example for local symbols.
   * This is not only more efficient, it's also more correct. It's not always
   * the case that the symbol can be found through the hash table.
   */
  Elf_Addr
  elf_lookup(linker_file_t lf, Elf_Word symidx, int deps)
  {
          elf_file_t ef = (elf_file_t)lf;
          const Elf_Sym *sym;
          const char *symbol;
  
          /* Don't even try to lookup the symbol if the index is bogus. */
          if (symidx >= ef->nchains)
                  return (0);
  
          sym = ef->symtab + symidx;
  
          /*
           * Don't do a full lookup when the symbol is local. It may even
           * fail because it may not be found through the hash table.
           */
          if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
                  /* Force lookup failure when we have an insanity. */
                  if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0)
                          return (0);
                  return ((Elf_Addr)ef->address + sym->st_value);
          }
  
          /*
           * XXX we can avoid doing a hash table based lookup for global
           * symbols as well. This however is not always valid, so we'll
           * just do it the hard way for now. Performance tweaks can
           * always be added.
           */
  
          symbol = ef->strtab + sym->st_name;
  
          /* Force a lookup failure if the symbol name is bogus. */
          if (*symbol == 0)
                  return (0);
  
          return ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
  }
  
  static void
  link_elf_reloc_local(linker_file_t lf)
  {
      const Elf_Rel *rellim;
      const Elf_Rel *rel;
      const Elf_Rela *relalim;
      const Elf_Rela *rela;
      elf_file_t ef = (elf_file_t)lf;
  
      /* Perform relocations without addend if there are any: */
      if ((rel = ef->rel) != NULL) {
          rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
          while (rel < rellim) {
              elf_reloc_local(lf, rel, ELF_RELOC_REL);
              rel++;
          }
      }
  
      /* Perform relocations with addend if there are any: */
      if ((rela = ef->rela) != NULL) {
          relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
          while (rela < relalim) {
              elf_reloc_local(lf, rela, ELF_RELOC_RELA);
              rela++;
          }
      }
  }

Cache object: bc3122d397b131df261df86fddd4b2d4