link_elf.c

Go to the documentation of this file.

/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * 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("$FreeBSD$");
 
#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>
#ifdef SPARSE_MAPPING
#include <sys/mman.h>
#endif
#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 <sys/sysctl.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>
 
#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_lookup_debug_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_debug_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 int      elf_lookup(linker_file_t, Elf_Size, int, Elf_Addr *);
 
static kobj_method_t link_elf_methods[] = {
        KOBJMETHOD(linker_lookup_symbol,        link_elf_lookup_symbol),
        KOBJMETHOD(linker_lookup_debug_symbol,  link_elf_lookup_debug_symbol),
        KOBJMETHOD(linker_symbol_values,        link_elf_symbol_values),
        KOBJMETHOD(linker_debug_symbol_values,  link_elf_debug_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),
        KOBJMETHOD_END
};
 
static struct linker_class link_elf_class = {
#if ELF_TARG_CLASS == ELFCLASS32
        "elf32",
#else
        "elf64",
#endif
        link_elf_methods, sizeof(struct elf_file)
};
 
static bool link_elf_leak_locals = true;
SYSCTL_BOOL(_debug, OID_AUTO, link_elf_leak_locals,
    CTLFLAG_RWTUN, &link_elf_leak_locals, 0,
    "Allow local symbols to participate in global module symbol resolution");
 
typedef int (*elf_reloc_fn)(linker_file_t lf, Elf_Addr relocbase,
    const void *data, int type, elf_lookup_fn lookup);
 
static int      parse_dynamic(elf_file_t);
static int      relocate_file(elf_file_t);
static int      relocate_file1(elf_file_t ef, elf_lookup_fn lookup,
                    elf_reloc_fn reloc, bool ifuncs);
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 */
 
/*
 * 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);
}
 
static void
link_elf_invoke_ctors(caddr_t addr, size_t size)
{
        void (**ctor)(void);
        size_t i, cnt;
 
        if (addr == NULL || size == 0)
                return;
        cnt = size / sizeof(*ctor);
        ctor = (void *)addr;
        for (i = 0; i < cnt; i++) {
                if (ctor[i] != NULL)
                        (*ctor[i])();
        }
}
 
/*
 * 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
 
        /* Invoke .ctors */
        link_elf_invoke_ctors(lf->ctors_addr, lf->ctors_size);
        return (0);
}
 
#ifdef RELOCATABLE_KERNEL
/*
 * __startkernel and __endkernel are symbols set up as relocation canaries.
 *
 * They are defined in locore to reference linker script symbols at the
 * beginning and end of the LOAD area. This has the desired side effect of
 * giving us variables that have relative relocations pointing at them, so
 * relocation of the kernel object will cause the variables to be updated
 * automatically by the runtime linker when we initialize.
 *
 * There are two main reasons to relocate the kernel:
 * 1) If the loader needed to load the kernel at an alternate load address.
 * 2) If the kernel is switching address spaces on machines like POWER9
 *    under Radix where the high bits of the effective address are used to
 *    differentiate between hypervisor, host, guest, and problem state.
 */
extern vm_offset_t __startkernel, __endkernel;
#endif
 
static unsigned long kern_relbase = KERNBASE;
 
SYSCTL_ULONG(_kern, OID_AUTO, base_address, CTLFLAG_RD,
        SYSCTL_NULL_ULONG_PTR, KERNBASE, "Kernel base address");
SYSCTL_ULONG(_kern, OID_AUTO, relbase_address, CTLFLAG_RD,
        &kern_relbase, 0, "Kernel relocated base address");
 
static void
link_elf_init(void* arg)
{
        Elf_Dyn *dp;
        Elf_Addr *ctors_addrp;
        Elf_Size *ctors_sizep;
        caddr_t modptr, baseptr, sizeptr;
        elf_file_t ef;
        const 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");
        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;
#ifdef RELOCATABLE_KERNEL
        /* Compute relative displacement */
        ef->address = (caddr_t) (__startkernel - KERNBASE);
#else
        ef->address = 0;
#endif
#ifdef SPARSE_MAPPING
        ef->object = NULL;
#endif
        ef->dynamic = dp;
 
        if (dp != NULL)
                parse_dynamic(ef);
#ifdef RELOCATABLE_KERNEL
        linker_kernel_file->address = (caddr_t)__startkernel;
        linker_kernel_file->size = (intptr_t)(__endkernel - __startkernel);
        kern_relbase = (unsigned long)__startkernel;
#else
        linker_kernel_file->address += KERNBASE;
        linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;
#endif
 
        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;
                ctors_addrp = (Elf_Addr *)preload_search_info(modptr,
                        MODINFO_METADATA | MODINFOMD_CTORS_ADDR);
                ctors_sizep = (Elf_Size *)preload_search_info(modptr,
                        MODINFO_METADATA | MODINFOMD_CTORS_SIZE);
                if (ctors_addrp != NULL && ctors_sizep != NULL) {
                        linker_kernel_file->ctors_addr = ef->address +
                            *ctors_addrp;
                        linker_kernel_file->ctors_size = *ctors_sizep;
                }
        }
        (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, NULL);
 
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 elf_cpu_parse_dynamic(ef->address, ef->dynamic);
}
 
#define LS_PADDING      0x90909090
static int
parse_dpcpu(elf_file_t ef)
{
        int error, size;
#if defined(__i386__)
        uint32_t pad;
#endif
 
        ef->pcpu_start = 0;
        ef->pcpu_stop = 0;
        error = link_elf_lookup_set(&ef->lf, "pcpu", (void ***)&ef->pcpu_start,
            (void ***)&ef->pcpu_stop, NULL);
        /* Error just means there is no pcpu set to relocate. */
        if (error != 0)
                return (0);
        size = (uintptr_t)ef->pcpu_stop - (uintptr_t)ef->pcpu_start;
        /* Empty set? */
        if (size < 1)
                return (0);
#if defined(__i386__)
        /* In case we do find __start/stop_set_ symbols double-check. */
        if (size < 4) {
                uprintf("Kernel module '%s' must be recompiled with "
                    "linker script\n", ef->lf.pathname);
                return (ENOEXEC);
        }
 
        /* Padding from linker-script correct? */
        pad = *(uint32_t *)((uintptr_t)ef->pcpu_stop - sizeof(pad));
        if (pad != LS_PADDING) {
                uprintf("Kernel module '%s' must be recompiled with "
                    "linker script, invalid padding %#04x (%#04x)\n",
                    ef->lf.pathname, pad, LS_PADDING);
                return (ENOEXEC);
        }
        /* If we only have valid padding, nothing to do. */
        if (size == 4)
                return (0);
#endif
        /*
         * 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(size);
        if (ef->pcpu_base == 0) {
                printf("%s: pcpu module space is out of space; "
                    "cannot allocate %d for %s\n",
                    __func__, size, ef->lf.pathname);
                return (ENOSPC);
        }
        memcpy((void *)ef->pcpu_base, (void *)ef->pcpu_start, size);
        dpcpu_copy((void *)ef->pcpu_base, size);
        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 error, size;
#if defined(__i386__)
        uint32_t pad;
#endif
 
        ef->vnet_start = 0;
        ef->vnet_stop = 0;
        error = link_elf_lookup_set(&ef->lf, "vnet", (void ***)&ef->vnet_start,
            (void ***)&ef->vnet_stop, NULL);
        /* Error just means there is no vnet data set to relocate. */
        if (error != 0)
                return (0);
        size = (uintptr_t)ef->vnet_stop - (uintptr_t)ef->vnet_start;
        /* Empty set? */
        if (size < 1)
                return (0);
#if defined(__i386__)
        /* In case we do find __start/stop_set_ symbols double-check. */
        if (size < 4) {
                uprintf("Kernel module '%s' must be recompiled with "
                    "linker script\n", ef->lf.pathname);
                return (ENOEXEC);
        }
 
        /* Padding from linker-script correct? */
        pad = *(uint32_t *)((uintptr_t)ef->vnet_stop - sizeof(pad));
        if (pad != LS_PADDING) {
                uprintf("Kernel module '%s' must be recompiled with "
                    "linker script, invalid padding %#04x (%#04x)\n",
                    ef->lf.pathname, pad, LS_PADDING);
                return (ENOEXEC);
        }
        /* If we only have valid padding, nothing to do. */
        if (size == 4)
                return (0);
#endif
        /*
         * 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(size);
        if (ef->vnet_base == 0) {
                printf("%s: vnet module space is out of space; "
                    "cannot allocate %d for %s\n",
                    __func__, size, ef->lf.pathname);
                return (ENOSPC);
        }
        memcpy((void *)ef->vnet_base, (void *)ef->vnet_start, size);
        vnet_data_copy((void *)ef->vnet_base, size);
        elf_set_add(&set_vnet_list, ef->vnet_start, ef->vnet_stop,
            ef->vnet_base);
 
        return (0);
}
#endif
#undef LS_PADDING
 
/*
 * Apply the specified protection to the loadable segments of a preloaded linker
 * file.
 */
static int
preload_protect(elf_file_t ef, vm_prot_t prot)
{
#if defined(__aarch64__) || defined(__amd64__)
        Elf_Ehdr *hdr;
        Elf_Phdr *phdr, *phlimit;
        vm_prot_t nprot;
        int error;
 
        error = 0;
        hdr = (Elf_Ehdr *)ef->address;
        phdr = (Elf_Phdr *)(ef->address + hdr->e_phoff);
        phlimit = phdr + hdr->e_phnum;
        for (; phdr < phlimit; phdr++) {
                if (phdr->p_type != PT_LOAD)
                        continue;
 
                nprot = prot | VM_PROT_READ;
                if ((phdr->p_flags & PF_W) != 0)
                        nprot |= VM_PROT_WRITE;
                if ((phdr->p_flags & PF_X) != 0)
                        nprot |= VM_PROT_EXECUTE;
                error = pmap_change_prot((vm_offset_t)ef->address +
                    phdr->p_vaddr, round_page(phdr->p_memsz), nprot);
                if (error != 0)
                        break;
        }
        return (error);
#else
        return (0);
#endif
}
 
#ifdef __arm__
/*
 * Locate the ARM exception/unwind table info for DDB and stack(9) use by
 * searching for the section header that describes it.  There may be no unwind
 * info, for example in a module containing only data.
 */
static void
link_elf_locate_exidx(linker_file_t lf, Elf_Shdr *shdr, int nhdr)
{
        int i;
 
        for (i = 0; i < nhdr; i++) {
                if (shdr[i].sh_type == SHT_ARM_EXIDX) {
                        lf->exidx_addr = shdr[i].sh_addr + lf->address;
                        lf->exidx_size = shdr[i].sh_size;
                        break;
                }
        }
}
 
/*
 * Locate the section headers metadata in a preloaded module, then use it to
 * locate the exception/unwind table in the module.  The size of the metadata
 * block is stored in a uint32 word immediately before the data itself, and a
 * comment in preload_search_info() says it is safe to rely on that.
 */
static void
link_elf_locate_exidx_preload(struct linker_file *lf, caddr_t modptr)
{
        uint32_t *modinfo;
        Elf_Shdr *shdr;
        uint32_t  nhdr;
 
        modinfo = (uint32_t *)preload_search_info(modptr,
            MODINFO_METADATA | MODINFOMD_SHDR);
        if (modinfo != NULL) {
                shdr = (Elf_Shdr *)modinfo;
                nhdr = modinfo[-1] / sizeof(Elf_Shdr);
                link_elf_locate_exidx(lf, shdr, nhdr);
        }
}
 
#endif /* __arm__ */
 
static int
link_elf_link_preload(linker_class_t cls, const char *filename,
    linker_file_t *result)
{
        Elf_Addr *ctors_addrp;
        Elf_Size *ctors_sizep;
        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 = NULL;
#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;
 
        ctors_addrp = (Elf_Addr *)preload_search_info(modptr,
            MODINFO_METADATA | MODINFOMD_CTORS_ADDR);
        ctors_sizep = (Elf_Size *)preload_search_info(modptr,
            MODINFO_METADATA | MODINFOMD_CTORS_SIZE);
        if (ctors_addrp != NULL && ctors_sizep != NULL) {
                lf->ctors_addr = ef->address + *ctors_addrp;
                lf->ctors_size = *ctors_sizep;
        }
 
#ifdef __arm__
        link_elf_locate_exidx_preload(lf, modptr);
#endif
 
        error = parse_dynamic(ef);
        if (error == 0)
                error = parse_dpcpu(ef);
#ifdef VIMAGE
        if (error == 0)
                error = parse_vnet(ef);
#endif
        if (error == 0)
                error = preload_protect(ef, VM_PROT_ALL);
        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;
        error = relocate_file(ef);
        if (error == 0)
                error = preload_protect(ef, VM_PROT_NONE);
        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, segbase;
        int nbytes, i;
        Elf_Phdr *phdr;
        Elf_Phdr *phlimit;
        Elf_Phdr *segs[MAXSEGS];
        int nsegs;
        Elf_Phdr *phdyn;
        caddr_t mapbase;
        size_t mapsize;
        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 shstrindex;
        int symcnt;
        int strcnt;
        char *shstrs;
 
        shdr = NULL;
        lf = NULL;
        shstrs = NULL;
 
        NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename);
        flags = FREAD;
        error = vn_open(&nd, &flags, 0, NULL);
        if (error != 0)
                return (error);
        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;
        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_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_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_pager_allocate(OBJT_PHYS, NULL, mapsize, VM_PROT_ALL,
            0, thread0.td_ucred);
        if (ef->object == NULL) {
                error = ENOMEM;
                goto out;
        }
#ifdef __amd64__
        mapbase = (caddr_t)KERNBASE;
#else
        mapbase = (caddr_t)vm_map_min(kernel_map);
#endif
        /*
         * Mapping protections are downgraded after relocation processing.
         */
        error = vm_map_find(kernel_map, ef->object, 0,
            (vm_offset_t *)&mapbase, mapsize, 0, VMFS_OPTIMAL_SPACE,
            VM_PROT_ALL, VM_PROT_ALL, 0);
        if (error != 0) {
                vm_object_deallocate(ef->object);
                ef->object = NULL;
                goto out;
        }
#else
        mapbase = malloc_exec(mapsize, M_LINKER, M_WAITOK);
#endif
        ef->address = mapbase;
 
        /*
         * Read the text and data sections and zero the bss.
         */
        for (i = 0; i < nsegs; i++) {
                segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
 
#ifdef SPARSE_MAPPING
                /*
                 * Consecutive segments may have different mapping permissions,
                 * so be strict and verify that their mappings do not overlap.
                 */
                if (((vm_offset_t)segbase & PAGE_MASK) != 0) {
                        error = EINVAL;
                        goto out;
                }
 
                error = vm_map_wire(kernel_map,
                    (vm_offset_t)segbase,
                    (vm_offset_t)segbase + round_page(segs[i]->p_memsz),
                    VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
                if (error != KERN_SUCCESS) {
                        error = ENOMEM;
                        goto out;
                }
#endif
 
                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 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);
        error = linker_load_dependencies(lf);
        vn_lock(nd.ni_vp, LK_EXCLUSIVE | LK_RETRY);
        if (error != 0)
                goto out;
        error = relocate_file(ef);
        if (error != 0)
                goto out;
 
#ifdef SPARSE_MAPPING
        /*
         * Downgrade permissions on text segment mappings now that relocation
         * processing is complete.  Restrict permissions on read-only segments.
         */
        for (i = 0; i < nsegs; i++) {
                vm_prot_t prot;
 
                if (segs[i]->p_type != PT_LOAD)
                        continue;
 
                prot = VM_PROT_READ;
                if ((segs[i]->p_flags & PF_W) != 0)
                        prot |= VM_PROT_WRITE;
                if ((segs[i]->p_flags & PF_X) != 0)
                        prot |= VM_PROT_EXECUTE;
                segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
                error = vm_map_protect(kernel_map,
                    (vm_offset_t)segbase,
                    (vm_offset_t)segbase + round_page(segs[i]->p_memsz),
                    prot, 0, VM_MAP_PROTECT_SET_PROT);
                if (error != KERN_SUCCESS) {
                        error = ENOMEM;
                        goto out;
                }
        }
#endif
 
        /*
         * 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;
 
        /* Read section string table */
        shstrindex = hdr->e_shstrndx;
        if (shstrindex != 0 && shdr[shstrindex].sh_type == SHT_STRTAB &&
            shdr[shstrindex].sh_size != 0) {
                nbytes = shdr[shstrindex].sh_size;
                shstrs = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
                error = vn_rdwr(UIO_READ, nd.ni_vp, (caddr_t)shstrs, nbytes,
                    shdr[shstrindex].sh_offset, 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;
                } else if (shstrs != NULL && shdr[i].sh_name != 0 &&
                    strcmp(shstrs + shdr[i].sh_name, ".ctors") == 0) {
                        /* Record relocated address and size of .ctors. */
                        lf->ctors_addr = mapbase + shdr[i].sh_addr - base_vaddr;
                        lf->ctors_size = shdr[i].sh_size;
                }
        }
        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:
 
#ifdef __arm__
        link_elf_locate_exidx(lf, shdr, hdr->e_shnum);
#endif
 
        error = link_elf_link_common_finish(lf);
        if (error != 0)
                goto out;
 
        *result = lf;
 
out:
        VOP_UNLOCK(nd.ni_vp);
        vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
        if (error != 0 && lf != NULL)
                linker_file_unload(lf, LINKER_UNLOAD_FORCE);
        free(shdr, M_LINKER);
        free(firstpage, M_LINKER);
        free(shstrs, M_LINKER);
 
        return (error);
}
 
Elf_Addr
elf_relocaddr(linker_file_t lf, Elf_Addr x)
{
        elf_file_t ef;
 
        KASSERT(lf->ops->cls == (kobj_class_t)&link_elf_class,
            ("elf_relocaddr: unexpected linker file %p", lf));
 
        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
        free(ef->address, M_LINKER);
#endif
        free(ef->symbase, M_LINKER);
        free(ef->strbase, M_LINKER);
        free(ef->ctftab, M_LINKER);
        free(ef->ctfoff, M_LINKER);
        free(ef->typoff, M_LINKER);
}
 
static void
link_elf_unload_preload(linker_file_t file)
{
 
        if (file->pathname != NULL)
                preload_delete_name(file->pathname);
}
 
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
symbol_type(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 (ELF_ST_TYPE(ref->st_info));
        }
        return (STT_NOTYPE);
}
 
static int
relocate_file1(elf_file_t ef, elf_lookup_fn lookup, elf_reloc_fn reloc,
    bool ifuncs)
{
        const Elf_Rel *rel;
        const Elf_Rela *rela;
        const char *symname;
 
#define APPLY_RELOCS(iter, tbl, tblsize, type) do {                     \
        for ((iter) = (tbl); (iter) != NULL &&                          \
            (iter) < (tbl) + (tblsize) / sizeof(*(iter)); (iter)++) {   \
                if ((symbol_type(ef, (iter)->r_info) ==                 \
                    STT_GNU_IFUNC ||                                    \
                    elf_is_ifunc_reloc((iter)->r_info)) != ifuncs)      \
                        continue;                                       \
                if (reloc(&ef->lf, (Elf_Addr)ef->address,               \
                    (iter), (type), lookup)) {                          \
                        symname = symbol_name(ef, (iter)->r_info);      \
                        printf("link_elf: symbol %s undefined\n",       \
                            symname);                                   \
                        return (ENOENT);                                \
                }                                                       \
        }                                                               \
} while (0)
 
        APPLY_RELOCS(rel, ef->rel, ef->relsize, ELF_RELOC_REL);
        APPLY_RELOCS(rela, ef->rela, ef->relasize, ELF_RELOC_RELA);
        APPLY_RELOCS(rel, ef->pltrel, ef->pltrelsize, ELF_RELOC_REL);
        APPLY_RELOCS(rela, ef->pltrela, ef->pltrelasize, ELF_RELOC_RELA);
 
#undef APPLY_RELOCS
 
        return (0);
}
 
static int
relocate_file(elf_file_t ef)
{
        int error;
 
        error = relocate_file1(ef, elf_lookup, elf_reloc, false);
        if (error == 0)
                error = relocate_file1(ef, elf_lookup, elf_reloc, true);
        return (error);
}
 
/*
 * 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_symbol1(linker_file_t lf, const char *name, c_linker_sym_t *sym,
    bool see_local)
{
        elf_file_t ef = (elf_file_t) lf;
        unsigned long symnum;
        const Elf_Sym* symp;
        const char *strp;
        unsigned long hash;
 
        /* 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 ||
                            ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC))) {
                                if (see_local ||
                                    ELF_ST_BIND(symp->st_info) != STB_LOCAL) {
                                        *sym = (c_linker_sym_t) symp;
                                        return (0);
                                }
                        }
                        return (ENOENT);
                }
 
                symnum = ef->chains[symnum];
        }
 
        return (ENOENT);
}
 
static int
link_elf_lookup_symbol(linker_file_t lf, const char *name, c_linker_sym_t *sym)
{
        if (link_elf_leak_locals)
                return (link_elf_lookup_debug_symbol(lf, name, sym));
        return (link_elf_lookup_symbol1(lf, name, sym, false));
}
 
static int
link_elf_lookup_debug_symbol(linker_file_t lf, const char *name,
    c_linker_sym_t *sym)
{
        elf_file_t ef = (elf_file_t)lf;
        const Elf_Sym* symp;
        const char *strp;
        int i;
 
        if (link_elf_lookup_symbol1(lf, name, sym, true) == 0)
                return (0);
 
        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 ||
                            ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC))) {
                                *sym = (c_linker_sym_t) symp;
                                return (0);
                        }
                        return (ENOENT);
                }
        }
 
        return (ENOENT);
}
 
static int
link_elf_symbol_values1(linker_file_t lf, c_linker_sym_t sym,
    linker_symval_t *symval, bool see_local)
{
        elf_file_t ef;
        const Elf_Sym *es;
        caddr_t val;
 
        ef = (elf_file_t)lf;
        es = (const Elf_Sym *)sym;
        if (es >= ef->symtab && es < ef->symtab + ef->nchains) {
                if (!see_local && ELF_ST_BIND(es->st_info) == STB_LOCAL)
                        return (ENOENT);
                symval->name = ef->strtab + es->st_name;
                val = (caddr_t)ef->address + es->st_value;
                if (ELF_ST_TYPE(es->st_info) == STT_GNU_IFUNC)
                        val = ((caddr_t (*)(void))val)();
                symval->value = val;
                symval->size = es->st_size;
                return (0);
        }
        return (ENOENT);
}
 
static int
link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym,
    linker_symval_t *symval)
{
        if (link_elf_leak_locals)
                return (link_elf_debug_symbol_values(lf, sym, symval));
        return (link_elf_symbol_values1(lf, sym, symval, false));
}
 
static int
link_elf_debug_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;
        caddr_t val;
 
        if (link_elf_symbol_values1(lf, sym, symval, true) == 0)
                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;
                val = (caddr_t)ef->address + es->st_value;
                if (ELF_ST_TYPE(es->st_info) == STT_GNU_IFUNC)
                        val = ((caddr_t (*)(void))val)();
                symval->value = val;
                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 = 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 = 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 ||
                    ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC)) {
                        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 ||
                    ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC)) {
                        error = link_elf_debug_symbol_values(file,
                            (c_linker_sym_t) symp, &symval);
                        if (error == 0)
                                error = callback(file, i, &symval, opaque);
                        if (error != 0)
                                return (error);
                }
        }
        return (0);
}
 
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 int
elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *res)
{
        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) {
                *res = 0;
                return (EINVAL);
        }
 
        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) {
                        *res = 0;
                        return (EINVAL);
                }
                *res = ((Elf_Addr)ef->address + sym->st_value);
                return (0);
        }
 
        /*
         * 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) {
                *res = 0;
                return (EINVAL);
        }
 
        addr = ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
        if (addr == 0 && ELF_ST_BIND(sym->st_info) != STB_WEAK) {
                *res = 0;
                return (EINVAL);
        }
 
        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
        *res = addr;
        return (0);
}
 
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);
}
 
#if defined(__i386__) || defined(__amd64__) || defined(__aarch64__) || defined(__powerpc__)
/*
 * Use this lookup routine when performing relocations early during boot.
 * The generic lookup routine depends on kobj, which is not initialized
 * at that point.
 */
static int
elf_lookup_ifunc(linker_file_t lf, Elf_Size symidx, int deps __unused,
    Elf_Addr *res)
{
        elf_file_t ef;
        const Elf_Sym *symp;
        caddr_t val;
 
        ef = (elf_file_t)lf;
        symp = ef->symtab + symidx;
        if (ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC) {
                val = (caddr_t)ef->address + symp->st_value;
                *res = ((Elf_Addr (*)(void))val)();
                return (0);
        }
        return (ENOENT);
}
 
void
link_elf_ireloc(caddr_t kmdp)
{
        struct elf_file eff;
        elf_file_t ef;
 
        ef = &eff;
 
        bzero_early(ef, sizeof(*ef));
 
        ef->modptr = kmdp;
        ef->dynamic = (Elf_Dyn *)&_DYNAMIC;
 
#ifdef RELOCATABLE_KERNEL
        ef->address = (caddr_t) (__startkernel - KERNBASE);
#else
        ef->address = 0;
#endif
        parse_dynamic(ef);
 
        link_elf_preload_parse_symbols(ef);
        relocate_file1(ef, elf_lookup_ifunc, elf_reloc, true);
}
 
#if defined(__aarch64__) || defined(__amd64__)
void
link_elf_late_ireloc(void)
{
        elf_file_t ef;
 
        KASSERT(linker_kernel_file != NULL,
            ("link_elf_late_ireloc: No kernel linker file found"));
        ef = (elf_file_t)linker_kernel_file;
 
        relocate_file1(ef, elf_lookup_ifunc, elf_reloc_late, true);
}
#endif
#endif