link_elf.c

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/*-
 * 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.
 */

#include <sys/cdefs.h>
__FBSDID("$BSDSUniX$");

#include "opt_ddb.h"
#include "opt_gdb.h"

#include <sys/param.h>
#include <sys/systm.h>
#ifdef GPROF
#include <sys/gmon.h>
#endif
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/mount.h>
#include <sys/pcpu.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>

#include <net/vnet.h>

#include <security/mac/mac_framework.h>

#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>

#ifdef DDB_CTF
#include <net/zlib.h>
#endif

#include "linker_if.h"

#define MAXSEGS 4

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 */
        caddr_t         ctftab;         /* CTF table */
        long            ctfcnt;         /* number of bytes in CTF table */
        caddr_t         ctfoff;         /* CTF offset table */
        caddr_t         typoff;         /* Type offset table */
        long            typlen;         /* Number of type entries. */
        Elf_Addr        pcpu_start;     /* Pre-relocation pcpu set start. */
        Elf_Addr        pcpu_stop;      /* Pre-relocation pcpu set stop. */
        Elf_Addr        pcpu_base;      /* Relocated pcpu set address. */
#ifdef VIMAGE
        Elf_Addr        vnet_start;     /* Pre-relocation vnet set start. */
        Elf_Addr        vnet_stop;      /* Pre-relocation vnet set stop. */
        Elf_Addr        vnet_base;      /* Relocated vnet set address. */
#endif
#ifdef GDB
        struct link_map gdb;            /* hooks for gdb */
#endif
} *elf_file_t;

struct elf_set {
        Elf_Addr        es_start;
        Elf_Addr        es_stop;
        Elf_Addr        es_base;
        TAILQ_ENTRY(elf_set)    es_link;
};

TAILQ_HEAD(elf_set_head, elf_set);

#include <kern/kern_ctf.c>

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,
                    c_linker_sym_t *, long *);

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 int      link_elf_each_function_nameval(linker_file_t,
                    linker_function_nameval_callback_t, void *);
static void     link_elf_reloc_local(linker_file_t);
static long     link_elf_symtab_get(linker_file_t, const Elf_Sym **);
static long     link_elf_strtab_get(linker_file_t, caddr_t *);
static Elf_Addr elf_lookup(linker_file_t, Elf_Size, int);

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),
        KOBJMETHOD(linker_each_function_nameval, link_elf_each_function_nameval),
        KOBJMETHOD(linker_ctf_get,              link_elf_ctf_get),
        KOBJMETHOD(linker_symtab_get,           link_elf_symtab_get),
        KOBJMETHOD(linker_strtab_get,           link_elf_strtab_get),
        { 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);
static int      relocate_file(elf_file_t);
static int      link_elf_preload_parse_symbols(elf_file_t);

static struct elf_set_head set_pcpu_list;
#ifdef VIMAGE
static struct elf_set_head set_vnet_list;
#endif

static void
elf_set_add(struct elf_set_head *list, Elf_Addr start, Elf_Addr stop, Elf_Addr base)
{
        struct elf_set *set, *iter;

        set = malloc(sizeof(*set), M_LINKER, M_WAITOK);
        set->es_start = start;
        set->es_stop = stop;
        set->es_base = base;

        TAILQ_FOREACH(iter, list, es_link) {

                KASSERT((set->es_start < iter->es_start && set->es_stop < iter->es_stop) ||
                    (set->es_start > iter->es_start && set->es_stop > iter->es_stop),
                    ("linker sets intersection: to insert: 0x%jx-0x%jx; inserted: 0x%jx-0x%jx",
                    (uintmax_t)set->es_start, (uintmax_t)set->es_stop,
                    (uintmax_t)iter->es_start, (uintmax_t)iter->es_stop));

                if (iter->es_start > set->es_start) {
                        TAILQ_INSERT_BEFORE(iter, set, es_link);
                        break;
                }
        }

        if (iter == NULL)
                TAILQ_INSERT_TAIL(list, set, es_link);
}

static int
elf_set_find(struct elf_set_head *list, Elf_Addr addr, Elf_Addr *start, Elf_Addr *base)
{
        struct elf_set *set;

        TAILQ_FOREACH(set, list, es_link) {
                if (addr < set->es_start)
                        return (0);
                if (addr < set->es_stop) {
                        *start = set->es_start;
                        *base = set->es_base;
                        return (1);
                }
        }

        return (0);
}

static void
elf_set_delete(struct elf_set_head *list, Elf_Addr start)
{
        struct elf_set *set;

        TAILQ_FOREACH(set, list, es_link) {
                if (start < set->es_start)
                        break;
                if (start == set->es_start) {
                        TAILQ_REMOVE(list, set, es_link);
                        free(set, M_LINKER);
                        return;
                }
        }
        KASSERT(0, ("deleting unknown linker set (start = 0x%jx)",
            (uintmax_t)start));
}

#ifdef GDB
static void     r_debug_state(struct r_debug *, struct link_map *);

/*
 * A list of loaded modules for GDB to use for loading symbols.
 */
struct r_debug r_debug;

#define GDB_STATE(s) do {                               \
        r_debug.r_state = s; r_debug_state(NULL, NULL); \
} while (0)

/*
 * 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 /* GDB */

#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 *filename, const char *s)
{
        if (filename == NULL)
                printf("kldload: %s\n", s);
        else
                printf("kldload: %s: %s\n", filename, 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 GDB
        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 != 0)
                return (error);

#ifdef GDB
        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 != NULL)
                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("%s: Can't create linker structures for kernel",
                    __func__);

        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 != NULL)
                parse_dynamic(ef);
        linker_kernel_file->address = (caddr_t) KERNBASE;
        linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;

        if (modptr != NULL) {
                ef->modptr = modptr;
                baseptr = preload_search_info(modptr, MODINFO_ADDR);
                if (baseptr != NULL)
                        linker_kernel_file->address = *(caddr_t *)baseptr;
                sizeptr = preload_search_info(modptr, MODINFO_SIZE);
                if (sizeptr != NULL)
                        linker_kernel_file->size = *(size_t *)sizeptr;
        }
        (void)link_elf_preload_parse_symbols(ef);

#ifdef GDB
        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);
        linker_kernel_file->flags |= LINKER_FILE_LINKED;
        TAILQ_INIT(&set_pcpu_list);
#ifdef VIMAGE
        TAILQ_INIT(&set_vnet_list);
#endif
}

SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_THIRD, 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 GDB
                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
parse_dpcpu(elf_file_t ef)
{
        int count;
        int error;

        ef->pcpu_start = 0;
        ef->pcpu_stop = 0;
        error = link_elf_lookup_set(&ef->lf, "pcpu", (void ***)&ef->pcpu_start,
            (void ***)&ef->pcpu_stop, &count);
        /* Error just means there is no pcpu set to relocate. */
        if (error != 0)
                return (0);
        count *= sizeof(void *);
        /*
         * Allocate space in the primary pcpu area.  Copy in our
         * initialization from the data section and then initialize
         * all per-cpu storage from that.
         */
        ef->pcpu_base = (Elf_Addr)(uintptr_t)dpcpu_alloc(count);
        if (ef->pcpu_base == 0)
                return (ENOSPC);
        memcpy((void *)ef->pcpu_base, (void *)ef->pcpu_start, count);
        dpcpu_copy((void *)ef->pcpu_base, count);
        elf_set_add(&set_pcpu_list, ef->pcpu_start, ef->pcpu_stop,
            ef->pcpu_base);

        return (0);
}

#ifdef VIMAGE
static int
parse_vnet(elf_file_t ef)
{
        int count;
        int error;

        ef->vnet_start = 0;
        ef->vnet_stop = 0;
        error = link_elf_lookup_set(&ef->lf, "vnet", (void ***)&ef->vnet_start,
            (void ***)&ef->vnet_stop, &count);
        /* Error just means there is no vnet data set to relocate. */
        if (error != 0)
                return (0);
        count *= sizeof(void *);
        /*
         * Allocate space in the primary vnet area.  Copy in our
         * initialization from the data section and then initialize
         * all per-vnet storage from that.
         */
        ef->vnet_base = (Elf_Addr)(uintptr_t)vnet_data_alloc(count);
        if (ef->vnet_base == 0)
                return (ENOSPC);
        memcpy((void *)ef->vnet_base, (void *)ef->vnet_start, count);
        vnet_data_copy((void *)ef->vnet_base, count);
        elf_set_add(&set_vnet_list, ef->vnet_start, ef->vnet_stop,
            ef->vnet_base);

        return (0);
}
#endif

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 == 0)
                error = parse_dpcpu(ef);
#ifdef VIMAGE
        if (error == 0)
                error = parse_vnet(ef);
#endif
        if (error != 0) {
                linker_file_unload(lf, LINKER_UNLOAD_FORCE);
                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 != 0)
                        goto out;
    }
#endif
        error = relocate_file(ef);
        if (error != 0)
                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[MAXSEGS];
        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;
        ssize_t resid;
        int flags;
        elf_file_t ef;
        linker_file_t lf;
        Elf_Shdr *shdr;
        int symtabindex;
        int symstrindex;
        int symcnt;
        int strcnt;
        int vfslocked;

        shdr = NULL;
        lf = NULL;

        NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, filename, td);
        flags = FREAD;
        error = vn_open(&nd, &flags, 0, NULL);
        if (error != 0)
                return (error);
        vfslocked = NDHASGIANT(&nd);
        NDFREE(&nd, NDF_ONLY_PNBUF);
        if (nd.ni_vp->v_type != VREG) {
                error = ENOEXEC;
                firstpage = NULL;
                goto out;
        }
#ifdef MAC
        error = mac_kld_check_load(curthread->td_ucred, nd.ni_vp);
        if (error != 0) {
                firstpage = NULL;
                goto out;
        }
#endif

        /*
         * Read the elf header from the file.
         */
        firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK);
        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 != 0)
                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(filename, "Unsupported file layout");
                error = ENOEXEC;
                goto out;
        }
        if (hdr->e_ident[EI_VERSION] != EV_CURRENT ||
            hdr->e_version != EV_CURRENT) {
                link_elf_error(filename, "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(filename, "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(filename, "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 == MAXSEGS) {
                                link_elf_error(filename, "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:
                        error = ENOSYS;
                        goto out;
                }

                ++phdr;
        }
        if (phdyn == NULL) {
                link_elf_error(filename, "Object is not dynamically-linked");
                error = ENOEXEC;
                goto out;
        }
        if (nsegs == 0) {
                link_elf_error(filename, "No 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[nsegs - 1]->p_vaddr +
            segs[nsegs - 1]->p_memsz);
        mapsize = base_vlimit - base_vaddr;

        lf = linker_make_file(filename, &link_elf_class);
        if (lf == NULL) {
                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;
        }
        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 != 0) {
                vm_object_deallocate(ef->object);
                ef->object = 0;
                goto out;
        }
#else
        ef->address = malloc(mapsize, M_LINKER, M_WAITOK);
#endif
        mapbase = ef->address;

        /*
         * Read the text and data sections and zero the bss.
         */
        for (i = 0; i < nsegs; 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 != 0)
                        goto out;
                bzero(segbase + segs[i]->p_filesz,
                    segs[i]->p_memsz - segs[i]->p_filesz);

#ifdef SPARSE_MAPPING
                /*
                 * Wire down the pages
                 */
                error = vm_map_wire(kernel_map,
                    (vm_offset_t) segbase,
                    (vm_offset_t) segbase + segs[i]->p_memsz,
                    VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
                if (error != KERN_SUCCESS) {
                        error = ENOMEM;
                        goto out;
                }
#endif
        }

#ifdef GPROF
        /* Update profiling information with the new text segment. */
        mtx_lock(&Giant);
        kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr +
            segs[0]->p_memsz));
        mtx_unlock(&Giant);
#endif

        ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);

        lf->address = ef->address;
        lf->size = mapsize;

        error = parse_dynamic(ef);
        if (error != 0)
                goto out;
        error = parse_dpcpu(ef);
        if (error != 0)
                goto out;
#ifdef VIMAGE
        error = parse_vnet(ef);
        if (error != 0)
                goto out;
#endif
        link_elf_reloc_local(lf);

        VOP_UNLOCK(nd.ni_vp, 0);
        error = linker_load_dependencies(lf);
        vn_lock(nd.ni_vp, LK_EXCLUSIVE | LK_RETRY);
        if (error != 0)
                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 != 0)
                        goto out;
    }
#endif
        error = relocate_file(ef);
        if (error != 0)
                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);
        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 != 0)
                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);

        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 != 0)
                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 != 0)
                goto out;

        ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
        ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
        ef->ddbstrcnt = strcnt;
        ef->ddbstrtab = ef->strbase;

nosyms:
        error = link_elf_link_common_finish(lf);
        if (error != 0)
                goto out;

        *result = lf;

out:
        VOP_UNLOCK(nd.ni_vp, 0);
        vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
        VFS_UNLOCK_GIANT(vfslocked);
        if (error != 0 && lf != NULL)
                linker_file_unload(lf, LINKER_UNLOAD_FORCE);
        if (shdr != NULL)
                free(shdr, M_LINKER);
        if (firstpage != NULL)
                free(firstpage, M_LINKER);

        return (error);
}

Elf_Addr
elf_relocaddr(linker_file_t lf, Elf_Addr x)
{
        elf_file_t ef;

        ef = (elf_file_t)lf;
        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
        return (x);
}


static void
link_elf_unload_file(linker_file_t file)
{
        elf_file_t ef = (elf_file_t) file;

        if (ef->pcpu_base != 0) {
                dpcpu_free((void *)ef->pcpu_base,
                    ef->pcpu_stop - ef->pcpu_start);
                elf_set_delete(&set_pcpu_list, ef->pcpu_start);
        }
#ifdef VIMAGE
        if (ef->vnet_base != 0) {
                vnet_data_free((void *)ef->vnet_base,
                    ef->vnet_stop - ef->vnet_start);
                elf_set_delete(&set_vnet_list, ef->vnet_start);
        }
#endif
#ifdef GDB
        if (ef->gdb.l_ld != NULL) {
                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 != NULL) {
                vm_map_remove(kernel_map, (vm_offset_t) ef->address,
                    (vm_offset_t) ef->address
                    + (ef->object->size << PAGE_SHIFT));
        }
#else
        if (ef->address != NULL)
                free(ef->address, M_LINKER);
#endif
        if (ef->symbase != NULL)
                free(ef->symbase, M_LINKER);
        if (ef->strbase != NULL)
                free(ef->strbase, M_LINKER);
        if (ef->ctftab != NULL)
                free(ef->ctftab, M_LINKER);
        if (ef->ctfoff != NULL)
                free(ef->ctfoff, M_LINKER);
        if (ef->typoff != NULL)
                free(ef->typoff, M_LINKER);
}

static void
link_elf_unload_preload(linker_file_t file)
{
        if (file->filename != NULL)
                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);
        }
        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 != NULL) {
                rellim = (const Elf_Rel *)
                    ((const char *)ef->rel + ef->relsize);
                while (rel < rellim) {
                        if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel,
                            ELF_RELOC_REL, elf_lookup)) {
                                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 != NULL) {
                relalim = (const Elf_Rela *)
                    ((const char *)ef->rela + ef->relasize);
                while (rela < relalim) {
                        if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela,
                            ELF_RELOC_RELA, elf_lookup)) {
                                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 != NULL) {
                rellim = (const Elf_Rel *)
                    ((const char *)ef->pltrel + ef->pltrelsize);
                while (rel < rellim) {
                        if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel,
                            ELF_RELOC_REL, elf_lookup)) {
                                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 != NULL) {
                relalim = (const Elf_Rela *)
                    ((const char *)ef->pltrela + ef->pltrelasize);
                while (rela < relalim) {
                        if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela,
                            ELF_RELOC_RELA, elf_lookup)) {
                                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;

        /* If we don't have a hash, bail. */
        if (ef->buckets == NULL || ef->nbuckets == 0) {
                printf("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) {
                        printf("%s: corrupt symbol table\n", __func__);
                        return (ENOENT);
                }

                symp = ef->symtab + symnum;
                if (symp->st_name == 0) {
                        printf("%s: corrupt symbol table\n", __func__);
                        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);
                        }
                        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);
                        }
                        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);

        /* get address of first entry */
        snprintf(setsym, len, "%s%s", "__start_set_", name);
        error = link_elf_lookup_symbol(lf, setsym, &sym);
        if (error != 0)
                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 != 0)
                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 != NULL)
                *startp = start;
        if (stopp != NULL)
                *stopp = stop;
        if (countp != NULL)
                *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 != 0)
                                return (error);
                }
        }
        return (0);
}

static int
link_elf_each_function_nameval(linker_file_t file,
    linker_function_nameval_callback_t callback, void *opaque)
{
        linker_symval_t symval;
        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 = link_elf_symbol_values(file,
                            (c_linker_sym_t) symp, &symval);
                        if (error != 0)
                                return (error);
                        error = callback(file, i, &symval, opaque);
                        if (error != 0)
                                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_Size 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_Size 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.
 */
static Elf_Addr
elf_lookup(linker_file_t lf, Elf_Size symidx, int deps)
{
        elf_file_t ef = (elf_file_t)lf;
        const Elf_Sym *sym;
        const char *symbol;
        Elf_Addr addr, start, base;

        /* 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);

        addr = ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));

        if (elf_set_find(&set_pcpu_list, addr, &start, &base))
                addr = addr - start + base;
#ifdef VIMAGE
        else if (elf_set_find(&set_vnet_list, addr, &start, &base))
                addr = addr - start + base;
#endif
        return addr;
}

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, (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++;
                }
        }
}

static long
link_elf_symtab_get(linker_file_t lf, const Elf_Sym **symtab)
{
        elf_file_t ef = (elf_file_t)lf;

        *symtab = ef->ddbsymtab;

        if (*symtab == NULL)
                return (0);

        return (ef->ddbsymcnt);
}

static long
link_elf_strtab_get(linker_file_t lf, caddr_t *strtab)
{
        elf_file_t ef = (elf_file_t)lf;

        *strtab = ef->ddbstrtab;

        if (*strtab == NULL)
                return (0);

        return (ef->ddbstrcnt);
}