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

     /*-
      * Copyright (c) 1998 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: src/sys/kern/link_elf.c,v 1.24 1999/12/24 15:33:36 bde Exp $
     */
    
    #include <sys/param.h>
    #include <sys/kernel.h>
    #include <sys/systm.h>
    #include <sys/malloc.h>
    #include <sys/proc.h>
    #include <sys/nlookup.h>
    #include <sys/fcntl.h>
    #include <sys/vnode.h>
    #include <sys/linker.h>
    #include <machine/elf.h>
    
    #include <vm/vm.h>
    #include <vm/vm_param.h>
    #include <vm/vm_zone.h>
    #include <sys/lock.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>
    
    #if defined(__x86_64__) && defined(_KERNEL_VIRTUAL)
    #include <stdio.h>
    #endif
    
    static int      link_elf_preload_file(const char *, linker_file_t *);
    static int      link_elf_preload_finish(linker_file_t);
    static int      link_elf_load_file(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_module(linker_file_t);
    static int      link_elf_lookup_set(linker_file_t, const char *,
                            void ***, void ***, int *);
    static int      elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *);
    static void link_elf_reloc_local(linker_file_t lf);
    
    static struct linker_class_ops link_elf_class_ops = {
        link_elf_load_file,
        link_elf_preload_file,
    };
    
    static struct linker_file_ops link_elf_file_ops = {
        .lookup_symbol = link_elf_lookup_symbol,
        .symbol_values = link_elf_symbol_values,
        .search_symbol = link_elf_search_symbol,
        .unload = link_elf_unload_file,
        .lookup_set = link_elf_lookup_set
    };
    
    static struct linker_file_ops link_elf_module_ops = {
        .lookup_symbol = link_elf_lookup_symbol,
        .symbol_values = link_elf_symbol_values,
        .search_symbol = link_elf_search_symbol,
        .preload_finish = link_elf_preload_finish,
        .unload = link_elf_unload_module,
        .lookup_set = link_elf_lookup_set,
    };
    
    typedef struct elf_file {
        caddr_t             address;        /* Relocation address */
    #ifdef SPARSE_MAPPING
        vm_object_t         object;         /* VM object to hold file pages */
    #endif
        const 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 */
   } *elf_file_t;
   
   static int              parse_dynamic(linker_file_t lf);
   static int              relocate_file(linker_file_t lf);
   static int              parse_module_symbols(linker_file_t lf);
   
   /*
    * The kernel symbol table starts here.
    */
   extern struct _dynamic _DYNAMIC;
   
   static void
   link_elf_init(void* arg)
   {
       Elf_Dyn     *dp;
       caddr_t     modptr, baseptr, sizeptr;
       elf_file_t  ef;
       char        *modname;
   
   #if ELF_TARG_CLASS == ELFCLASS32
       linker_add_class("elf32", NULL, &link_elf_class_ops);
   #else
       linker_add_class("elf64", NULL, &link_elf_class_ops);
   #endif
   
       dp = (Elf_Dyn*) &_DYNAMIC;
       if (dp) {
           ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_INTWAIT | M_ZERO);
           ef->address = NULL;
   #ifdef SPARSE_MAPPING
           ef->object = NULL;
   #endif
           ef->dynamic = dp;
           modname = 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, ef, &link_elf_file_ops);
           if (linker_kernel_file == NULL)
               panic("link_elf_init: Can't create linker structures for kernel");
           parse_dynamic(linker_kernel_file);
   #if defined(__x86_64__) && defined(_KERNEL_VIRTUAL)
           fprintf(stderr, "WARNING: KERNBASE being used\n");
   #endif
           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;
           }
           parse_module_symbols(linker_kernel_file);
           linker_current_file = linker_kernel_file;
           linker_kernel_file->flags |= LINKER_FILE_LINKED;
       }
   }
   
   SYSINIT(link_elf, SI_BOOT2_KLD, SI_ORDER_SECOND, link_elf_init, 0);
   
   static int
   parse_module_symbols(linker_file_t lf)
   {
       elf_file_t ef = lf->priv;
       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) {
           kprintf("Symbols are corrupt!\n");
           return EINVAL;
       }
   
       strcnt = *(long *)base;
       base += sizeof(long);
       strtab = base;
       base += roundup(strcnt, sizeof(long));
   
       if (base > esym || base < ssym) {
           kprintf("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(linker_file_t lf)
   {
       elf_file_t ef = lf->priv;
       const 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;
           }
       }
   
       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 void
   link_elf_error(const char *s)
   {
       kprintf("kldload: %s\n", s);
   }
   
   static int
   link_elf_preload_file(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 module preloaded.
        */
       modptr = preload_search_by_name(filename);
       if (modptr == NULL)
           return ENOENT;
   
       /* It's preloaded, check we can handle it and collect information */
       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);
   
       ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO);
       ef->modptr = modptr;
       ef->address = *(caddr_t *)baseptr;
   #ifdef SPARSE_MAPPING
       ef->object = NULL;
   #endif
       dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
       ef->dynamic = (Elf_Dyn *)dp;
       lf = linker_make_file(filename, ef, &link_elf_module_ops);
       if (lf == NULL) {
           kfree(ef, M_LINKER);
           return ENOMEM;
       }
       lf->address = ef->address;
       lf->size = *(size_t *)sizeptr;
   
       error = parse_dynamic(lf);
       if (error) {
           linker_file_unload(lf);
           return error;
       }
       link_elf_reloc_local(lf);
       *result = lf;
       return (0);
   }
   
   static int
   link_elf_preload_finish(linker_file_t lf)
   {
       int                 error;
   
       error = relocate_file(lf);
       if (error)
           return error;
       parse_module_symbols(lf);
   
       return (0);
   }
   
   static int
   link_elf_load_file(const char* filename, linker_file_t* result)
   {
       struct nlookupdata nd;
       struct thread *td = curthread;      /* XXX */
       struct proc *p = td->td_proc;
       struct vnode *vp;
       Elf_Ehdr *hdr;
       caddr_t firstpage;
       int nbytes, i;
       Elf_Phdr *phdr;
       Elf_Phdr *phlimit;
       Elf_Phdr *segs[2];
       int nsegs;
       Elf_Phdr *phdyn;
       caddr_t mapbase;
       size_t mapsize;
       Elf_Addr base_vaddr;
       Elf_Addr base_vlimit;
       int error = 0;
       int resid;
       elf_file_t ef;
       linker_file_t lf;
       char *pathname;
       Elf_Shdr *shdr;
       int symtabindex;
       int symstrindex;
       int symcnt;
       int strcnt;
   
       /* XXX Hack for firmware loading where p == NULL */
       if (p == NULL) {
           p = &proc0;
       }
   
       KKASSERT(p != NULL);
       if (p->p_ucred == NULL) {
           kprintf("link_elf_load_file: cannot load '%s' from filesystem"
                   " this early\n", filename);
           return ENOENT;
       }
       shdr = NULL;
       lf = NULL;
       pathname = linker_search_path(filename);
       if (pathname == NULL)
           return ENOENT;
   
       error = nlookup_init(&nd, pathname, UIO_SYSSPACE, NLC_FOLLOW|NLC_LOCKVP);
       if (error == 0)
           error = vn_open(&nd, NULL, FREAD, 0);
       kfree(pathname, M_LINKER);
       if (error) {
           nlookup_done(&nd);
           return error;
       }
       vp = nd.nl_open_vp;
       nd.nl_open_vp = NULL;
       nlookup_done(&nd);
   
       /*
        * Read the elf header from the file.
        */
       firstpage = kmalloc(PAGE_SIZE, M_LINKER, M_WAITOK);
       hdr = (Elf_Ehdr *)firstpage;
       error = vn_rdwr(UIO_READ, vp, firstpage, PAGE_SIZE, 0,
                       UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid);
       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) {
           error = ENOSYS;
           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;
       while (phdr < phlimit) {
           switch (phdr->p_type) {
   
           case PT_LOAD:
               if (nsegs == 2) {
                   link_elf_error("Too many sections");
                   error = ENOEXEC;
                   goto out;
               }
               segs[nsegs] = phdr;
               ++nsegs;
               break;
   
           case PT_PHDR:
               break;
   
           case PT_DYNAMIC:
               phdyn = phdr;
               break;
   
           case PT_INTERP:
               error = ENOSYS;
               goto out;
           }
   
           ++phdr;
       }
       if (phdyn == NULL) {
           link_elf_error("Object is not dynamically-linked");
           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_vaddr = trunc_page(segs[0]->p_vaddr);
       base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz);
       mapsize = base_vlimit - base_vaddr;
   
       ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO);
   #ifdef SPARSE_MAPPING
       ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
       if (ef->object == NULL) {
           kfree(ef, M_LINKER);
           error = ENOMEM;
           goto out;
       }
       vm_object_hold(ef->object);
       vm_object_reference_locked(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, PAGE_SIZE,
                           1, VM_MAPTYPE_NORMAL,
                           VM_PROT_ALL, VM_PROT_ALL,
                           0);
       vm_object_drop(ef->object);
       if (error) {
           vm_object_deallocate(ef->object);
           kfree(ef, M_LINKER);
           goto out;
       }
   #else
       ef->address = kmalloc(mapsize, M_LINKER, M_WAITOK);
   #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, vp,
                           segbase, segs[i]->p_filesz, segs[i]->p_offset,
                           UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid);
           if (error) {
   #ifdef SPARSE_MAPPING
               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
               kfree(ef->address, M_LINKER);
   #endif
               kfree(ef, M_LINKER);
               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,
                       0);
   #endif
       }
   
       ef->dynamic = (const Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
   
       lf = linker_make_file(filename, ef, &link_elf_file_ops);
       if (lf == NULL) {
   #ifdef SPARSE_MAPPING
           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
           kfree(ef->address, M_LINKER);
   #endif
           kfree(ef, M_LINKER);
           error = ENOMEM;
           goto out;
       }
       lf->address = ef->address;
       lf->size = mapsize;
   
       error = parse_dynamic(lf);
       if (error)
           goto out;
       link_elf_reloc_local(lf);
       error = linker_load_dependencies(lf);
       if (error)
           goto out;
       error = relocate_file(lf);
       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 = kmalloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
       error = vn_rdwr(UIO_READ, vp,
                       (caddr_t)shdr, nbytes, hdr->e_shoff,
                       UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid);
       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 = kmalloc(symcnt, M_LINKER, M_WAITOK);
       strcnt = shdr[symstrindex].sh_size;
       ef->strbase = kmalloc(strcnt, M_LINKER, M_WAITOK);
       error = vn_rdwr(UIO_READ, vp,
                       ef->symbase, symcnt, shdr[symtabindex].sh_offset,
                       UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid);
       if (error)
           goto out;
       error = vn_rdwr(UIO_READ, vp,
                       ef->strbase, strcnt, shdr[symstrindex].sh_offset,
                       UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid);
       if (error)
           goto out;
   
       ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
       ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
       ef->ddbstrcnt = strcnt;
       ef->ddbstrtab = ef->strbase;
   
   nosyms:
   
       *result = lf;
   
   out:
       if (error && lf)
           linker_file_unload(lf);
       if (shdr)
           kfree(shdr, M_LINKER);
       if (firstpage)
           kfree(firstpage, M_LINKER);
       vn_unlock(vp);
       vn_close(vp, FREAD);
   
       return error;
   }
   
   Elf_Addr
   elf_relocaddr(linker_file_t lf, Elf_Addr x)
   {
   #if 0
       elf_file_t ef;
   
       ef = lf->priv;
       if (x >= ef->pcpu_start && x < ef->pcpu_stop)
           return ((x - ef->pcpu_start) + ef->pcpu_base);
   #ifdef VIMAGE
       if (x >= ef->vnet_start && x < ef->vnet_stop)
           return ((x - ef->vnet_start) + ef->vnet_base);
   #endif
   #endif
       return (x);
   }
   
   static void
   link_elf_unload_file(linker_file_t file)
   {
       elf_file_t ef = file->priv;
   
       if (ef) {
   #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)
               kfree(ef->address, M_LINKER);
   #endif
           if (ef->symbase)
               kfree(ef->symbase, M_LINKER);
           if (ef->strbase)
               kfree(ef->strbase, M_LINKER);
           kfree(ef, M_LINKER);
       }
   }
   
   static void
   link_elf_unload_module(linker_file_t file)
   {
       elf_file_t ef = file->priv;
   
       if (ef)
           kfree(ef, M_LINKER);
       if (file->filename)
           preload_delete_name(file->filename);
   }
   
   static const char *
   symbol_name(elf_file_t ef, Elf_Size 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(linker_file_t lf)
   {
       elf_file_t ef = lf->priv;
       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(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, elf_lookup)) {
                   symname = symbol_name(ef, rel->r_info);
                   kprintf("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(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, elf_lookup)) {
                   symname = symbol_name(ef, rela->r_info);
                   kprintf("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(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, elf_lookup)) {
                   symname = symbol_name(ef, rel->r_info);
                   kprintf("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) {
               symname = symbol_name(ef, rela->r_info);
               if (elf_reloc(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, elf_lookup)) {
                   kprintf("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;
   }
   
   int
   link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym)
   {
       elf_file_t ef = lf->priv;
       unsigned long symnum;
       const Elf_Sym* symp;
       const char *strp;
       unsigned long hash;
       int i;
   
       /* If we don't have a hash, bail. */
       if (ef->buckets == NULL || ef->nbuckets == 0) {
           kprintf("link_elf_lookup_symbol: missing symbol hash table\n");
           return ENOENT;
       }
   
       /* First, search hashed global symbols */
       hash = elf_hash(name);
       symnum = ef->buckets[hash % ef->nbuckets];
   
       while (symnum != STN_UNDEF) {
           if (symnum >= ef->nchains) {
               kprintf("link_elf_lookup_symbol: corrupt symbol table\n");
               return ENOENT;
           }
   
           symp = ef->symtab + symnum;
           if (symp->st_name == 0) {
               kprintf("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 = lf->priv;
       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 = 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 = 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 = lf->priv;
       u_long          off = (uintptr_t)(void *)value;
       u_long          diff = off;
       u_long          st_value;
       const Elf_Sym  *es;
       const Elf_Sym  *best = NULL;
       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 == NULL)
           *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 = kmalloc(len, M_LINKER, M_WAITOK);
  
      /* get address of first entry */
      ksnprintf(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 == NULL) {
          error = ESRCH;
          goto out;
      }
      start = (void **)symval.value;
  
      /* get address of last entry */
      ksnprintf(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 == NULL) {
          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:
      kfree(setsym, M_LINKER);
      return error;
  }
  
  /*
   * 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.
   */
  static int
  elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *result)
  {
      elf_file_t      ef = lf->priv;
      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 (ENOENT);
  
      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 (ENOENT);
          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 (ENOENT);
  
      return (linker_file_lookup_symbol(lf, symbol, deps, (caddr_t *)result));
  }
  static void
  link_elf_reloc_local(linker_file_t lf)
  {
      elf_file_t ef = lf->priv;
      const Elf_Rel *rellim;
      const Elf_Rel *rel;
      const Elf_Rela *relalim;
      const Elf_Rela *rela;
  
      /* 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, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
                              elf_lookup);
              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, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
                              elf_lookup);
              rela++;
          }
      }
  }

Cache object: a6653a82d8cb61333bbce31930e2eb66