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

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 2017 Dell EMC
      * Copyright (c) 2000-2001, 2003 David O'Brien
      * Copyright (c) 1995-1996 Søren Schmidt
      * Copyright (c) 1996 Peter Wemm
      * 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
     *    in this position and unchanged.
     * 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.
     * 3. The name of the author may not be used to endorse or promote products
     *    derived from this software without specific prior written permission
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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_capsicum.h"
    
    #include <sys/param.h>
    #include <sys/capsicum.h>
    #include <sys/compressor.h>
    #include <sys/exec.h>
    #include <sys/fcntl.h>
    #include <sys/imgact.h>
    #include <sys/imgact_elf.h>
    #include <sys/jail.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/mount.h>
    #include <sys/mman.h>
    #include <sys/namei.h>
    #include <sys/pioctl.h>
    #include <sys/proc.h>
    #include <sys/procfs.h>
    #include <sys/ptrace.h>
    #include <sys/racct.h>
    #include <sys/resourcevar.h>
    #include <sys/rwlock.h>
    #include <sys/sbuf.h>
    #include <sys/sf_buf.h>
    #include <sys/smp.h>
    #include <sys/systm.h>
    #include <sys/signalvar.h>
    #include <sys/stat.h>
    #include <sys/sx.h>
    #include <sys/syscall.h>
    #include <sys/sysctl.h>
    #include <sys/sysent.h>
    #include <sys/vnode.h>
    #include <sys/syslog.h>
    #include <sys/eventhandler.h>
    #include <sys/user.h>
    
    #include <vm/vm.h>
    #include <vm/vm_kern.h>
    #include <vm/vm_param.h>
    #include <vm/pmap.h>
    #include <vm/vm_map.h>
    #include <vm/vm_object.h>
    #include <vm/vm_extern.h>
    
    #include <machine/elf.h>
    #include <machine/md_var.h>
    
    #define ELF_NOTE_ROUNDSIZE      4
    #define OLD_EI_BRAND    8
    
    static int __elfN(check_header)(const Elf_Ehdr *hdr);
    static Elf_Brandinfo *__elfN(get_brandinfo)(struct image_params *imgp,
        const char *interp, int32_t *osrel, uint32_t *fctl0);
    static int __elfN(load_file)(struct proc *p, const char *file, u_long *addr,
        u_long *entry);
    static int __elfN(load_section)(struct image_params *imgp, vm_ooffset_t offset,
        caddr_t vmaddr, size_t memsz, size_t filsz, vm_prot_t prot);
    static int __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp);
    static bool __elfN(freebsd_trans_osrel)(const Elf_Note *note,
        int32_t *osrel);
    static bool kfreebsd_trans_osrel(const Elf_Note *note, int32_t *osrel);
   static boolean_t __elfN(check_note)(struct image_params *imgp,
       Elf_Brandnote *checknote, int32_t *osrel, uint32_t *fctl0);
   static vm_prot_t __elfN(trans_prot)(Elf_Word);
   static Elf_Word __elfN(untrans_prot)(vm_prot_t);
   
   SYSCTL_NODE(_kern, OID_AUTO, __CONCAT(elf, __ELF_WORD_SIZE), CTLFLAG_RW, 0,
       "");
   
   #define CORE_BUF_SIZE   (16 * 1024)
   
   int __elfN(fallback_brand) = -1;
   SYSCTL_INT(__CONCAT(_kern_elf, __ELF_WORD_SIZE), OID_AUTO,
       fallback_brand, CTLFLAG_RWTUN, &__elfN(fallback_brand), 0,
       __XSTRING(__CONCAT(ELF, __ELF_WORD_SIZE)) " brand of last resort");
   
   static int elf_legacy_coredump = 0;
   SYSCTL_INT(_debug, OID_AUTO, __elfN(legacy_coredump), CTLFLAG_RW, 
       &elf_legacy_coredump, 0,
       "include all and only RW pages in core dumps");
   
   int __elfN(nxstack) =
   #if defined(__amd64__) || defined(__powerpc64__) /* both 64 and 32 bit */ || \
       (defined(__arm__) && __ARM_ARCH >= 7) || defined(__aarch64__) || \
       defined(__riscv)
           1;
   #else
           0;
   #endif
   SYSCTL_INT(__CONCAT(_kern_elf, __ELF_WORD_SIZE), OID_AUTO,
       nxstack, CTLFLAG_RW, &__elfN(nxstack), 0,
       __XSTRING(__CONCAT(ELF, __ELF_WORD_SIZE)) ": enable non-executable stack");
   
   #if __ELF_WORD_SIZE == 32
   #if defined(__amd64__)
   int i386_read_exec = 0;
   SYSCTL_INT(_kern_elf32, OID_AUTO, read_exec, CTLFLAG_RW, &i386_read_exec, 0,
       "enable execution from readable segments");
   #endif
   #endif
   
   static u_long __elfN(pie_base) = ET_DYN_LOAD_ADDR;
   static int
   sysctl_pie_base(SYSCTL_HANDLER_ARGS)
   {
           u_long val;
           int error;
   
           val = __elfN(pie_base);
           error = sysctl_handle_long(oidp, &val, 0, req);
           if (error != 0 || req->newptr == NULL)
                   return (error);
           if ((val & PAGE_MASK) != 0)
                   return (EINVAL);
           __elfN(pie_base) = val;
           return (0);
   }
   SYSCTL_PROC(__CONCAT(_kern_elf, __ELF_WORD_SIZE), OID_AUTO, pie_base,
       CTLTYPE_ULONG | CTLFLAG_MPSAFE | CTLFLAG_RW, NULL, 0,
       sysctl_pie_base, "LU",
       "PIE load base without randomization");
   
   SYSCTL_NODE(__CONCAT(_kern_elf, __ELF_WORD_SIZE), OID_AUTO, aslr, CTLFLAG_RW, 0,
       "");
   #define ASLR_NODE_OID   __CONCAT(__CONCAT(_kern_elf, __ELF_WORD_SIZE), _aslr)
   
   static int __elfN(aslr_enabled) = 0;
   SYSCTL_INT(ASLR_NODE_OID, OID_AUTO, enable, CTLFLAG_RWTUN,
       &__elfN(aslr_enabled), 0,
       __XSTRING(__CONCAT(ELF, __ELF_WORD_SIZE))
       ": enable address map randomization");
   
   static int __elfN(pie_aslr_enabled) = 0;
   SYSCTL_INT(ASLR_NODE_OID, OID_AUTO, pie_enable, CTLFLAG_RWTUN,
       &__elfN(pie_aslr_enabled), 0,
       __XSTRING(__CONCAT(ELF, __ELF_WORD_SIZE))
       ": enable address map randomization for PIE binaries");
   
   static int __elfN(aslr_honor_sbrk) = 1;
   SYSCTL_INT(ASLR_NODE_OID, OID_AUTO, honor_sbrk, CTLFLAG_RW,
       &__elfN(aslr_honor_sbrk), 0,
       __XSTRING(__CONCAT(ELF, __ELF_WORD_SIZE)) ": assume sbrk is used");
   
   static int __elfN(aslr_stack_gap) = 3;
   SYSCTL_INT(ASLR_NODE_OID, OID_AUTO, stack_gap, CTLFLAG_RW,
       &__elfN(aslr_stack_gap), 0,
       __XSTRING(__CONCAT(ELF, __ELF_WORD_SIZE))
       ": maximum percentage of main stack to waste on a random gap");
   
   static Elf_Brandinfo *elf_brand_list[MAX_BRANDS];
   
   #define aligned(a, t)   (rounddown2((u_long)(a), sizeof(t)) == (u_long)(a))
   
   static const char FREEBSD_ABI_VENDOR[] = "FreeBSD";
   
   Elf_Brandnote __elfN(freebsd_brandnote) = {
           .hdr.n_namesz   = sizeof(FREEBSD_ABI_VENDOR),
           .hdr.n_descsz   = sizeof(int32_t),
           .hdr.n_type     = NT_FREEBSD_ABI_TAG,
           .vendor         = FREEBSD_ABI_VENDOR,
           .flags          = BN_TRANSLATE_OSREL,
           .trans_osrel    = __elfN(freebsd_trans_osrel)
   };
   
   static bool
   __elfN(freebsd_trans_osrel)(const Elf_Note *note, int32_t *osrel)
   {
           uintptr_t p;
   
           p = (uintptr_t)(note + 1);
           p += roundup2(note->n_namesz, ELF_NOTE_ROUNDSIZE);
           *osrel = *(const int32_t *)(p);
   
           return (true);
   }
   
   static const char GNU_ABI_VENDOR[] = "GNU";
   static int GNU_KFREEBSD_ABI_DESC = 3;
   
   Elf_Brandnote __elfN(kfreebsd_brandnote) = {
           .hdr.n_namesz   = sizeof(GNU_ABI_VENDOR),
           .hdr.n_descsz   = 16,   /* XXX at least 16 */
           .hdr.n_type     = 1,
           .vendor         = GNU_ABI_VENDOR,
           .flags          = BN_TRANSLATE_OSREL,
           .trans_osrel    = kfreebsd_trans_osrel
   };
   
   static bool
   kfreebsd_trans_osrel(const Elf_Note *note, int32_t *osrel)
   {
           const Elf32_Word *desc;
           uintptr_t p;
   
           p = (uintptr_t)(note + 1);
           p += roundup2(note->n_namesz, ELF_NOTE_ROUNDSIZE);
   
           desc = (const Elf32_Word *)p;
           if (desc[0] != GNU_KFREEBSD_ABI_DESC)
                   return (false);
   
           /*
            * Debian GNU/kFreeBSD embed the earliest compatible kernel version
            * (__FreeBSD_version: <major><two digit minor>Rxx) in the LSB way.
            */
           *osrel = desc[1] * 100000 + desc[2] * 1000 + desc[3];
   
           return (true);
   }
   
   int
   __elfN(insert_brand_entry)(Elf_Brandinfo *entry)
   {
           int i;
   
           for (i = 0; i < MAX_BRANDS; i++) {
                   if (elf_brand_list[i] == NULL) {
                           elf_brand_list[i] = entry;
                           break;
                   }
           }
           if (i == MAX_BRANDS) {
                   printf("WARNING: %s: could not insert brandinfo entry: %p\n",
                           __func__, entry);
                   return (-1);
           }
           return (0);
   }
   
   int
   __elfN(remove_brand_entry)(Elf_Brandinfo *entry)
   {
           int i;
   
           for (i = 0; i < MAX_BRANDS; i++) {
                   if (elf_brand_list[i] == entry) {
                           elf_brand_list[i] = NULL;
                           break;
                   }
           }
           if (i == MAX_BRANDS)
                   return (-1);
           return (0);
   }
   
   int
   __elfN(brand_inuse)(Elf_Brandinfo *entry)
   {
           struct proc *p;
           int rval = FALSE;
   
           sx_slock(&allproc_lock);
           FOREACH_PROC_IN_SYSTEM(p) {
                   if (p->p_sysent == entry->sysvec) {
                           rval = TRUE;
                           break;
                   }
           }
           sx_sunlock(&allproc_lock);
   
           return (rval);
   }
   
   static Elf_Brandinfo *
   __elfN(get_brandinfo)(struct image_params *imgp, const char *interp,
       int32_t *osrel, uint32_t *fctl0)
   {
           const Elf_Ehdr *hdr = (const Elf_Ehdr *)imgp->image_header;
           Elf_Brandinfo *bi, *bi_m;
           boolean_t ret;
           int i, interp_name_len;
   
           interp_name_len = interp != NULL ? strlen(interp) + 1 : 0;
   
           /*
            * We support four types of branding -- (1) the ELF EI_OSABI field
            * that SCO added to the ELF spec, (2) FreeBSD 3.x's traditional string
            * branding w/in the ELF header, (3) path of the `interp_path'
            * field, and (4) the ".note.ABI-tag" ELF section.
            */
   
           /* Look for an ".note.ABI-tag" ELF section */
           bi_m = NULL;
           for (i = 0; i < MAX_BRANDS; i++) {
                   bi = elf_brand_list[i];
                   if (bi == NULL)
                           continue;
                   if (interp != NULL && (bi->flags & BI_BRAND_ONLY_STATIC) != 0)
                           continue;
                   if (hdr->e_machine == bi->machine && (bi->flags &
                       (BI_BRAND_NOTE|BI_BRAND_NOTE_MANDATORY)) != 0) {
                           ret = __elfN(check_note)(imgp, bi->brand_note, osrel,
                               fctl0);
                           /* Give brand a chance to veto check_note's guess */
                           if (ret && bi->header_supported)
                                   ret = bi->header_supported(imgp);
                           /*
                            * If note checker claimed the binary, but the
                            * interpreter path in the image does not
                            * match default one for the brand, try to
                            * search for other brands with the same
                            * interpreter.  Either there is better brand
                            * with the right interpreter, or, failing
                            * this, we return first brand which accepted
                            * our note and, optionally, header.
                            */
                           if (ret && bi_m == NULL && interp != NULL &&
                               (bi->interp_path == NULL ||
                               (strlen(bi->interp_path) + 1 != interp_name_len ||
                               strncmp(interp, bi->interp_path, interp_name_len)
                               != 0))) {
                                   bi_m = bi;
                                   ret = 0;
                           }
                           if (ret)
                                   return (bi);
                   }
           }
           if (bi_m != NULL)
                   return (bi_m);
   
           /* If the executable has a brand, search for it in the brand list. */
           for (i = 0; i < MAX_BRANDS; i++) {
                   bi = elf_brand_list[i];
                   if (bi == NULL || (bi->flags & BI_BRAND_NOTE_MANDATORY) != 0 ||
                       (interp != NULL && (bi->flags & BI_BRAND_ONLY_STATIC) != 0))
                           continue;
                   if (hdr->e_machine == bi->machine &&
                       (hdr->e_ident[EI_OSABI] == bi->brand ||
                       (bi->compat_3_brand != NULL &&
                       strcmp((const char *)&hdr->e_ident[OLD_EI_BRAND],
                       bi->compat_3_brand) == 0))) {
                           /* Looks good, but give brand a chance to veto */
                           if (bi->header_supported == NULL ||
                               bi->header_supported(imgp)) {
                                   /*
                                    * Again, prefer strictly matching
                                    * interpreter path.
                                    */
                                   if (interp_name_len == 0 &&
                                       bi->interp_path == NULL)
                                           return (bi);
                                   if (bi->interp_path != NULL &&
                                       strlen(bi->interp_path) + 1 ==
                                       interp_name_len && strncmp(interp,
                                       bi->interp_path, interp_name_len) == 0)
                                           return (bi);
                                   if (bi_m == NULL)
                                           bi_m = bi;
                           }
                   }
           }
           if (bi_m != NULL)
                   return (bi_m);
   
           /* No known brand, see if the header is recognized by any brand */
           for (i = 0; i < MAX_BRANDS; i++) {
                   bi = elf_brand_list[i];
                   if (bi == NULL || bi->flags & BI_BRAND_NOTE_MANDATORY ||
                       bi->header_supported == NULL)
                           continue;
                   if (hdr->e_machine == bi->machine) {
                           ret = bi->header_supported(imgp);
                           if (ret)
                                   return (bi);
                   }
           }
   
           /* Lacking a known brand, search for a recognized interpreter. */
           if (interp != NULL) {
                   for (i = 0; i < MAX_BRANDS; i++) {
                           bi = elf_brand_list[i];
                           if (bi == NULL || (bi->flags &
                               (BI_BRAND_NOTE_MANDATORY | BI_BRAND_ONLY_STATIC))
                               != 0)
                                   continue;
                           if (hdr->e_machine == bi->machine &&
                               bi->interp_path != NULL &&
                               /* ELF image p_filesz includes terminating zero */
                               strlen(bi->interp_path) + 1 == interp_name_len &&
                               strncmp(interp, bi->interp_path, interp_name_len)
                               == 0 && (bi->header_supported == NULL ||
                               bi->header_supported(imgp)))
                                   return (bi);
                   }
           }
   
           /* Lacking a recognized interpreter, try the default brand */
           for (i = 0; i < MAX_BRANDS; i++) {
                   bi = elf_brand_list[i];
                   if (bi == NULL || (bi->flags & BI_BRAND_NOTE_MANDATORY) != 0 ||
                       (interp != NULL && (bi->flags & BI_BRAND_ONLY_STATIC) != 0))
                           continue;
                   if (hdr->e_machine == bi->machine &&
                       __elfN(fallback_brand) == bi->brand &&
                       (bi->header_supported == NULL ||
                       bi->header_supported(imgp)))
                           return (bi);
           }
           return (NULL);
   }
   
   static bool
   __elfN(phdr_in_zero_page)(const Elf_Ehdr *hdr)
   {
           return (hdr->e_phoff <= PAGE_SIZE &&
               (u_int)hdr->e_phentsize * hdr->e_phnum <= PAGE_SIZE - hdr->e_phoff);
   }
   
   static int
   __elfN(check_header)(const Elf_Ehdr *hdr)
   {
           Elf_Brandinfo *bi;
           int i;
   
           if (!IS_ELF(*hdr) ||
               hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
               hdr->e_ident[EI_DATA] != ELF_TARG_DATA ||
               hdr->e_ident[EI_VERSION] != EV_CURRENT ||
               hdr->e_phentsize != sizeof(Elf_Phdr) ||
               hdr->e_version != ELF_TARG_VER)
                   return (ENOEXEC);
   
           /*
            * Make sure we have at least one brand for this machine.
            */
   
           for (i = 0; i < MAX_BRANDS; i++) {
                   bi = elf_brand_list[i];
                   if (bi != NULL && bi->machine == hdr->e_machine)
                           break;
           }
           if (i == MAX_BRANDS)
                   return (ENOEXEC);
   
           return (0);
   }
   
   static int
   __elfN(map_partial)(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
       vm_offset_t start, vm_offset_t end, vm_prot_t prot)
   {
           struct sf_buf *sf;
           int error;
           vm_offset_t off;
   
           /*
            * Create the page if it doesn't exist yet. Ignore errors.
            */
           vm_map_fixed(map, NULL, 0, trunc_page(start), round_page(end) -
               trunc_page(start), VM_PROT_ALL, VM_PROT_ALL, MAP_CHECK_EXCL);
   
           /*
            * Find the page from the underlying object.
            */
           if (object != NULL) {
                   sf = vm_imgact_map_page(object, offset);
                   if (sf == NULL)
                           return (KERN_FAILURE);
                   off = offset - trunc_page(offset);
                   error = copyout((caddr_t)sf_buf_kva(sf) + off, (caddr_t)start,
                       end - start);
                   vm_imgact_unmap_page(sf);
                   if (error != 0)
                           return (KERN_FAILURE);
           }
   
           return (KERN_SUCCESS);
   }
   
   static int
   __elfN(map_insert)(struct image_params *imgp, vm_map_t map, vm_object_t object,
       vm_ooffset_t offset, vm_offset_t start, vm_offset_t end, vm_prot_t prot,
       int cow)
   {
           struct sf_buf *sf;
           vm_offset_t off;
           vm_size_t sz;
           int error, locked, rv;
   
           if (start != trunc_page(start)) {
                   rv = __elfN(map_partial)(map, object, offset, start,
                       round_page(start), prot);
                   if (rv != KERN_SUCCESS)
                           return (rv);
                   offset += round_page(start) - start;
                   start = round_page(start);
           }
           if (end != round_page(end)) {
                   rv = __elfN(map_partial)(map, object, offset +
                       trunc_page(end) - start, trunc_page(end), end, prot);
                   if (rv != KERN_SUCCESS)
                           return (rv);
                   end = trunc_page(end);
           }
           if (start >= end)
                   return (KERN_SUCCESS);
           if ((offset & PAGE_MASK) != 0) {
                   /*
                    * The mapping is not page aligned.  This means that we have
                    * to copy the data.
                    */
                   rv = vm_map_fixed(map, NULL, 0, start, end - start,
                       prot | VM_PROT_WRITE, VM_PROT_ALL, MAP_CHECK_EXCL);
                   if (rv != KERN_SUCCESS)
                           return (rv);
                   if (object == NULL)
                           return (KERN_SUCCESS);
                   for (; start < end; start += sz) {
                           sf = vm_imgact_map_page(object, offset);
                           if (sf == NULL)
                                   return (KERN_FAILURE);
                           off = offset - trunc_page(offset);
                           sz = end - start;
                           if (sz > PAGE_SIZE - off)
                                   sz = PAGE_SIZE - off;
                           error = copyout((caddr_t)sf_buf_kva(sf) + off,
                               (caddr_t)start, sz);
                           vm_imgact_unmap_page(sf);
                           if (error != 0)
                                   return (KERN_FAILURE);
                           offset += sz;
                   }
           } else {
                   vm_object_reference(object);
                   rv = vm_map_fixed(map, object, offset, start, end - start,
                       prot, VM_PROT_ALL, cow | MAP_CHECK_EXCL |
                       (object != NULL ? MAP_VN_EXEC : 0));
                   if (rv != KERN_SUCCESS) {
                           locked = VOP_ISLOCKED(imgp->vp);
                           VOP_UNLOCK(imgp->vp, 0);
                           vm_object_deallocate(object);
                           vn_lock(imgp->vp, locked | LK_RETRY);
                           return (rv);
                   } else if (object != NULL) {
                           MPASS(imgp->vp->v_object == object);
                           VOP_SET_TEXT_CHECKED(imgp->vp);
                   }
           }
           return (KERN_SUCCESS);
   }
   
   static int
   __elfN(load_section)(struct image_params *imgp, vm_ooffset_t offset,
       caddr_t vmaddr, size_t memsz, size_t filsz, vm_prot_t prot)
   {
           struct sf_buf *sf;
           size_t map_len;
           vm_map_t map;
           vm_object_t object;
           vm_offset_t off, map_addr;
           int error, rv, cow;
           size_t copy_len;
           vm_ooffset_t file_addr;
   
           /*
            * It's necessary to fail if the filsz + offset taken from the
            * header is greater than the actual file pager object's size.
            * If we were to allow this, then the vm_map_find() below would
            * walk right off the end of the file object and into the ether.
            *
            * While I'm here, might as well check for something else that
            * is invalid: filsz cannot be greater than memsz.
            */
           if ((filsz != 0 && (off_t)filsz + offset > imgp->attr->va_size) ||
               filsz > memsz) {
                   uprintf("elf_load_section: truncated ELF file\n");
                   return (ENOEXEC);
           }
   
           object = imgp->object;
           map = &imgp->proc->p_vmspace->vm_map;
           map_addr = trunc_page((vm_offset_t)vmaddr);
           file_addr = trunc_page(offset);
   
           /*
            * We have two choices.  We can either clear the data in the last page
            * of an oversized mapping, or we can start the anon mapping a page
            * early and copy the initialized data into that first page.  We
            * choose the second.
            */
           if (filsz == 0)
                   map_len = 0;
           else if (memsz > filsz)
                   map_len = trunc_page(offset + filsz) - file_addr;
           else
                   map_len = round_page(offset + filsz) - file_addr;
   
           if (map_len != 0) {
                   /* cow flags: don't dump readonly sections in core */
                   cow = MAP_COPY_ON_WRITE | MAP_PREFAULT |
                       (prot & VM_PROT_WRITE ? 0 : MAP_DISABLE_COREDUMP);
   
                   rv = __elfN(map_insert)(imgp, map, object, file_addr,
                       map_addr, map_addr + map_len, prot, cow);
                   if (rv != KERN_SUCCESS)
                           return (EINVAL);
   
                   /* we can stop now if we've covered it all */
                   if (memsz == filsz)
                           return (0);
           }
   
   
           /*
            * We have to get the remaining bit of the file into the first part
            * of the oversized map segment.  This is normally because the .data
            * segment in the file is extended to provide bss.  It's a neat idea
            * to try and save a page, but it's a pain in the behind to implement.
            */
           copy_len = filsz == 0 ? 0 : (offset + filsz) - trunc_page(offset +
               filsz);
           map_addr = trunc_page((vm_offset_t)vmaddr + filsz);
           map_len = round_page((vm_offset_t)vmaddr + memsz) - map_addr;
   
           /* This had damn well better be true! */
           if (map_len != 0) {
                   rv = __elfN(map_insert)(imgp, map, NULL, 0, map_addr,
                       map_addr + map_len, prot, 0);
                   if (rv != KERN_SUCCESS)
                           return (EINVAL);
           }
   
           if (copy_len != 0) {
                   sf = vm_imgact_map_page(object, offset + filsz);
                   if (sf == NULL)
                           return (EIO);
   
                   /* send the page fragment to user space */
                   off = trunc_page(offset + filsz) - trunc_page(offset + filsz);
                   error = copyout((caddr_t)sf_buf_kva(sf) + off,
                       (caddr_t)map_addr, copy_len);
                   vm_imgact_unmap_page(sf);
                   if (error != 0)
                           return (error);
           }
   
           /*
            * Remove write access to the page if it was only granted by map_insert
            * to allow copyout.
            */
           if ((prot & VM_PROT_WRITE) == 0)
                   vm_map_protect(map, trunc_page(map_addr), round_page(map_addr +
                       map_len), prot, FALSE);
   
           return (0);
   }
   
   static int
   __elfN(load_sections)(struct image_params *imgp, const Elf_Ehdr *hdr,
       const Elf_Phdr *phdr, u_long rbase, u_long *base_addrp)
   {
           vm_prot_t prot;
           u_long base_addr;
           bool first;
           int error, i;
   
           ASSERT_VOP_LOCKED(imgp->vp, __func__);
   
           base_addr = 0;
           first = true;
   
           for (i = 0; i < hdr->e_phnum; i++) {
                   if (phdr[i].p_type != PT_LOAD || phdr[i].p_memsz == 0)
                           continue;
   
                   /* Loadable segment */
                   prot = __elfN(trans_prot)(phdr[i].p_flags);
                   error = __elfN(load_section)(imgp, phdr[i].p_offset,
                       (caddr_t)(uintptr_t)phdr[i].p_vaddr + rbase,
                       phdr[i].p_memsz, phdr[i].p_filesz, prot);
                   if (error != 0)
                           return (error);
   
                   /*
                    * Establish the base address if this is the first segment.
                    */
                   if (first) {
                           base_addr = trunc_page(phdr[i].p_vaddr + rbase);
                           first = false;
                   }
           }
   
           if (base_addrp != NULL)
                   *base_addrp = base_addr;
   
           return (0);
   }
   
   /*
    * Load the file "file" into memory.  It may be either a shared object
    * or an executable.
    *
    * The "addr" reference parameter is in/out.  On entry, it specifies
    * the address where a shared object should be loaded.  If the file is
    * an executable, this value is ignored.  On exit, "addr" specifies
    * where the file was actually loaded.
    *
    * The "entry" reference parameter is out only.  On exit, it specifies
    * the entry point for the loaded file.
    */
   static int
   __elfN(load_file)(struct proc *p, const char *file, u_long *addr,
           u_long *entry)
   {
           struct {
                   struct nameidata nd;
                   struct vattr attr;
                   struct image_params image_params;
           } *tempdata;
           const Elf_Ehdr *hdr = NULL;
           const Elf_Phdr *phdr = NULL;
           struct nameidata *nd;
           struct vattr *attr;
           struct image_params *imgp;
           u_long rbase;
           u_long base_addr = 0;
           int error;
   
   #ifdef CAPABILITY_MODE
           /*
            * XXXJA: This check can go away once we are sufficiently confident
            * that the checks in namei() are correct.
            */
           if (IN_CAPABILITY_MODE(curthread))
                   return (ECAPMODE);
   #endif
   
           tempdata = malloc(sizeof(*tempdata), M_TEMP, M_WAITOK | M_ZERO);
           nd = &tempdata->nd;
           attr = &tempdata->attr;
           imgp = &tempdata->image_params;
   
           /*
            * Initialize part of the common data
            */
           imgp->proc = p;
           imgp->attr = attr;
   
           NDINIT(nd, LOOKUP, ISOPEN | FOLLOW | LOCKSHARED | LOCKLEAF,
               UIO_SYSSPACE, file, curthread);
           if ((error = namei(nd)) != 0) {
                   nd->ni_vp = NULL;
                   goto fail;
           }
           NDFREE(nd, NDF_ONLY_PNBUF);
           imgp->vp = nd->ni_vp;
   
           /*
            * Check permissions, modes, uid, etc on the file, and "open" it.
            */
           error = exec_check_permissions(imgp);
           if (error)
                   goto fail;
   
           error = exec_map_first_page(imgp);
           if (error)
                   goto fail;
   
           imgp->object = nd->ni_vp->v_object;
   
           hdr = (const Elf_Ehdr *)imgp->image_header;
           if ((error = __elfN(check_header)(hdr)) != 0)
                   goto fail;
           if (hdr->e_type == ET_DYN)
                   rbase = *addr;
           else if (hdr->e_type == ET_EXEC)
                   rbase = 0;
           else {
                   error = ENOEXEC;
                   goto fail;
           }
   
           /* Only support headers that fit within first page for now      */
           if (!__elfN(phdr_in_zero_page)(hdr)) {
                   error = ENOEXEC;
                   goto fail;
           }
   
           phdr = (const Elf_Phdr *)(imgp->image_header + hdr->e_phoff);
           if (!aligned(phdr, Elf_Addr)) {
                   error = ENOEXEC;
                   goto fail;
           }
   
           error = __elfN(load_sections)(imgp, hdr, phdr, rbase, &base_addr);
           if (error != 0)
                   goto fail;
   
           *addr = base_addr;
           *entry = (unsigned long)hdr->e_entry + rbase;
   
   fail:
           if (imgp->firstpage)
                   exec_unmap_first_page(imgp);
   
           if (nd->ni_vp) {
                   if (imgp->textset)
                           VOP_UNSET_TEXT_CHECKED(nd->ni_vp);
                   vput(nd->ni_vp);
           }
           free(tempdata, M_TEMP);
   
           return (error);
   }
   
   static u_long
   __CONCAT(rnd_, __elfN(base))(vm_map_t map __unused, u_long minv, u_long maxv,
       u_int align)
   {
           u_long rbase, res;
   
           MPASS(vm_map_min(map) <= minv);
           MPASS(maxv <= vm_map_max(map));
           MPASS(minv < maxv);
           MPASS(minv + align < maxv);
           arc4rand(&rbase, sizeof(rbase), 0);
           res = roundup(minv, (u_long)align) + rbase % (maxv - minv);
           res &= ~((u_long)align - 1);
           if (res >= maxv)
                   res -= align;
           KASSERT(res >= minv,
               ("res %#lx < minv %#lx, maxv %#lx rbase %#lx",
               res, minv, maxv, rbase));
           KASSERT(res < maxv,
               ("res %#lx > maxv %#lx, minv %#lx rbase %#lx",
               res, maxv, minv, rbase));
           return (res);
   }
   
   static int
   __elfN(enforce_limits)(struct image_params *imgp, const Elf_Ehdr *hdr,
       const Elf_Phdr *phdr, u_long et_dyn_addr)
   {
           struct vmspace *vmspace;
           const char *err_str;
           u_long text_size, data_size, total_size, text_addr, data_addr;
           u_long seg_size, seg_addr;
           int i;
   
           err_str = NULL;
           text_size = data_size = total_size = text_addr = data_addr = 0;
   
           for (i = 0; i < hdr->e_phnum; i++) {
                   if (phdr[i].p_type != PT_LOAD || phdr[i].p_memsz == 0)
                           continue;
   
                   seg_addr = trunc_page(phdr[i].p_vaddr + et_dyn_addr);
                   seg_size = round_page(phdr[i].p_memsz +
                       phdr[i].p_vaddr + et_dyn_addr - seg_addr);
   
                   /*
                    * Make the largest executable segment the official
                    * text segment and all others data.
                    *
                    * Note that obreak() assumes that data_addr + data_size == end
                    * of data load area, and the ELF file format expects segments
                    * to be sorted by address.  If multiple data segments exist,
                    * the last one will be used.
                    */
   
                   if ((phdr[i].p_flags & PF_X) != 0 && text_size < seg_size) {
                           text_size = seg_size;
                           text_addr = seg_addr;
                   } else {
                           data_size = seg_size;
                           data_addr = seg_addr;
                   }
                   total_size += seg_size;
           }
           
           if (data_addr == 0 && data_size == 0) {
                   data_addr = text_addr;
                   data_size = text_size;
           }
   
           /*
            * Check limits.  It should be safe to check the
            * limits after loading the segments since we do
            * not actually fault in all the segments pages.
            */
           PROC_LOCK(imgp->proc);
           if (data_size > lim_cur_proc(imgp->proc, RLIMIT_DATA))
                   err_str = "Data segment size exceeds process limit";
           else if (text_size > maxtsiz)
                   err_str = "Text segment size exceeds system limit";
           else if (total_size > lim_cur_proc(imgp->proc, RLIMIT_VMEM))
                   err_str = "Total segment size exceeds process limit";
           else if (racct_set(imgp->proc, RACCT_DATA, data_size) != 0)
                   err_str = "Data segment size exceeds resource limit";
           else if (racct_set(imgp->proc, RACCT_VMEM, total_size) != 0)
                   err_str = "Total segment size exceeds resource limit";
           PROC_UNLOCK(imgp->proc);
           if (err_str != NULL) {
                   uprintf("%s\n", err_str);
                   return (ENOMEM);
           }
   
           vmspace = imgp->proc->p_vmspace;
           vmspace->vm_tsize = text_size >> PAGE_SHIFT;
           vmspace->vm_taddr = (caddr_t)(uintptr_t)text_addr;
           vmspace->vm_dsize = data_size >> PAGE_SHIFT;
           vmspace->vm_daddr = (caddr_t)(uintptr_t)data_addr;
   
           return (0);
   }
   
   static int
   __elfN(get_interp)(struct image_params *imgp, const Elf_Phdr *phdr,
       char **interpp, bool *free_interpp)
   {
           struct thread *td;
           char *interp;
           int error, interp_name_len;
   
           KASSERT(phdr->p_type == PT_INTERP,
               ("%s: p_type %u != PT_INTERP", __func__, phdr->p_type));
           ASSERT_VOP_LOCKED(imgp->vp, __func__);
   
           td = curthread;
   
           /* Path to interpreter */
           if (phdr->p_filesz < 2 || phdr->p_filesz > MAXPATHLEN) {
                   uprintf("Invalid PT_INTERP\n");
                   return (ENOEXEC);
           }
   
           interp_name_len = phdr->p_filesz;
           if (phdr->p_offset > PAGE_SIZE ||
               interp_name_len > PAGE_SIZE - phdr->p_offset) {
                   /*
                    * The vnode lock might be needed by the pagedaemon to
                    * clean pages owned by the vnode.  Do not allow sleep
                    * waiting for memory with the vnode locked, instead
                    * try non-sleepable allocation first, and if it
                    * fails, go to the slow path were we drop the lock
                    * and do M_WAITOK.  A text reference prevents
                    * modifications to the vnode content.
                    */
                   interp = malloc(interp_name_len + 1, M_TEMP, M_NOWAIT);
                   if (interp == NULL) {
                           VOP_UNLOCK(imgp->vp, 0);
                           interp = malloc(interp_name_len + 1, M_TEMP, M_WAITOK);
                           vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
                   }
   
                   error = vn_rdwr(UIO_READ, imgp->vp, interp,
                       interp_name_len, phdr->p_offset,
                       UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred,
                       NOCRED, NULL, td);
                   if (error != 0) {
                           free(interp, M_TEMP);
                           uprintf("i/o error PT_INTERP %d\n", error);
                           return (error);
                   }
                   interp[interp_name_len] = '\0';
   
                   *interpp = interp;
                   *free_interpp = true;
                   return (0);
           }
  
          interp = __DECONST(char *, imgp->image_header) + phdr->p_offset;
          if (interp[interp_name_len - 1] != '\0') {
                  uprintf("Invalid PT_INTERP\n");
                  return (ENOEXEC);
          }
  
          *interpp = interp;
          *free_interpp = false;
          return (0);
  }
  
  static int
  __elfN(load_interp)(struct image_params *imgp, const Elf_Brandinfo *brand_info,
      const char *interp, u_long *addr, u_long *entry)
  {
          char *path;
          int error;
  
          if (brand_info->emul_path != NULL &&
              brand_info->emul_path[0] != '\0') {
                  path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
                  snprintf(path, MAXPATHLEN, "%s%s",
                      brand_info->emul_path, interp);
                  error = __elfN(load_file)(imgp->proc, path, addr, entry);
                  free(path, M_TEMP);
                  if (error == 0)
                          return (0);
          }
  
          if (brand_info->interp_newpath != NULL &&
              (brand_info->interp_path == NULL ||
              strcmp(interp, brand_info->interp_path) == 0)) {
                  error = __elfN(load_file)(imgp->proc,
                      brand_info->interp_newpath, addr, entry);
                  if (error == 0)
                          return (0);
          }
  
          error = __elfN(load_file)(imgp->proc, interp, addr, entry);
          if (error == 0)
                  return (0);
  
          uprintf("ELF interpreter %s not found, error %d\n", interp, error);
          return (error);
  }
  
  /*
   * Impossible et_dyn_addr initial value indicating that the real base
   * must be calculated later with some randomization applied.
   */
  #define ET_DYN_ADDR_RAND        1
  
  static int
  __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
  {
          struct thread *td;
          const Elf_Ehdr *hdr;
          const Elf_Phdr *phdr;
          Elf_Auxargs *elf_auxargs;
          struct vmspace *vmspace;
          vm_map_t map;
          char *interp;
          Elf_Brandinfo *brand_info;
          struct sysentvec *sv;
          u_long addr, baddr, et_dyn_addr, entry, proghdr;
          u_long maxalign, mapsz, maxv, maxv1;
          uint32_t fctl0;
          int32_t osrel;
          bool free_interp;
          int error, i, n;
  
          hdr = (const Elf_Ehdr *)imgp->image_header;
  
          /*
           * Do we have a valid ELF header ?
           *
           * Only allow ET_EXEC & ET_DYN here, reject ET_DYN later
           * if particular brand doesn't support it.
           */
          if (__elfN(check_header)(hdr) != 0 ||
              (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN))
                  return (-1);
  
          /*
           * From here on down, we return an errno, not -1, as we've
           * detected an ELF file.
           */
  
          if (!__elfN(phdr_in_zero_page)(hdr)) {
                  uprintf("Program headers not in the first page\n");
                  return (ENOEXEC);
          }
          phdr = (const Elf_Phdr *)(imgp->image_header + hdr->e_phoff); 
          if (!aligned(phdr, Elf_Addr)) {
                  uprintf("Unaligned program headers\n");
                  return (ENOEXEC);
          }
  
          n = error = 0;
          baddr = 0;
          osrel = 0;
          fctl0 = 0;
          entry = proghdr = 0;
          interp = NULL;
          free_interp = false;
          td = curthread;
          maxalign = PAGE_SIZE;
          mapsz = 0;
  
          for (i = 0; i < hdr->e_phnum; i++) {
                  switch (phdr[i].p_type) {
                  case PT_LOAD:
                          if (n == 0)
                                  baddr = phdr[i].p_vaddr;
                          if (phdr[i].p_align > maxalign)
                                  maxalign = phdr[i].p_align;
                          mapsz += phdr[i].p_memsz;
                          n++;
  
                          /*
                           * If this segment contains the program headers,
                           * remember their virtual address for the AT_PHDR
                           * aux entry. Static binaries don't usually include
                           * a PT_PHDR entry.
                           */
                          if (phdr[i].p_offset == 0 &&
                              hdr->e_phoff + hdr->e_phnum * hdr->e_phentsize
                                  <= phdr[i].p_filesz)
                                  proghdr = phdr[i].p_vaddr + hdr->e_phoff;
                          break;
                  case PT_INTERP:
                          /* Path to interpreter */
                          if (interp != NULL) {
                                  uprintf("Multiple PT_INTERP headers\n");
                                  error = ENOEXEC;
                                  goto ret;
                          }
                          error = __elfN(get_interp)(imgp, &phdr[i], &interp,
                              &free_interp);
                          if (error != 0)
                                  goto ret;
                          break;
                  case PT_GNU_STACK:
                          if (__elfN(nxstack)) {
                                  imgp->stack_prot =
                                      __elfN(trans_prot)(phdr[i].p_flags);
                                  if ((imgp->stack_prot & VM_PROT_RW) !=
                                      VM_PROT_RW) {
                                          uprintf("Invalid PT_GNU_STACK\n");
                                          error = ENOEXEC;
                                          goto ret;
                                  }
                          }
                          imgp->stack_sz = phdr[i].p_memsz;
                          break;
                  case PT_PHDR:   /* Program header table info */
                          proghdr = phdr[i].p_vaddr;
                          break;
                  }
          }
  
          brand_info = __elfN(get_brandinfo)(imgp, interp, &osrel, &fctl0);
          if (brand_info == NULL) {
                  uprintf("ELF binary type \"%u\" not known.\n",
                      hdr->e_ident[EI_OSABI]);
                  error = ENOEXEC;
                  goto ret;
          }
          sv = brand_info->sysvec;
          et_dyn_addr = 0;
          if (hdr->e_type == ET_DYN) {
                  if ((brand_info->flags & BI_CAN_EXEC_DYN) == 0) {
                          uprintf("Cannot execute shared object\n");
                          error = ENOEXEC;
                          goto ret;
                  }
                  /*
                   * Honour the base load address from the dso if it is
                   * non-zero for some reason.
                   */
                  if (baddr == 0) {
                          if ((sv->sv_flags & SV_ASLR) == 0 ||
                              (fctl0 & NT_FREEBSD_FCTL_ASLR_DISABLE) != 0)
                                  et_dyn_addr = __elfN(pie_base);
                          else if ((__elfN(pie_aslr_enabled) &&
                              (imgp->proc->p_flag2 & P2_ASLR_DISABLE) == 0) ||
                              (imgp->proc->p_flag2 & P2_ASLR_ENABLE) != 0)
                                  et_dyn_addr = ET_DYN_ADDR_RAND;
                          else
                                  et_dyn_addr = __elfN(pie_base);
                  }
          }
  
          /*
           * Avoid a possible deadlock if the current address space is destroyed
           * and that address space maps the locked vnode.  In the common case,
           * the locked vnode's v_usecount is decremented but remains greater
           * than zero.  Consequently, the vnode lock is not needed by vrele().
           * However, in cases where the vnode lock is external, such as nullfs,
           * v_usecount may become zero.
           *
           * The VV_TEXT flag prevents modifications to the executable while
           * the vnode is unlocked.
           */
          VOP_UNLOCK(imgp->vp, 0);
  
          /*
           * Decide whether to enable randomization of user mappings.
           * First, reset user preferences for the setid binaries.
           * Then, account for the support of the randomization by the
           * ABI, by user preferences, and make special treatment for
           * PIE binaries.
           */
          if (imgp->credential_setid) {
                  PROC_LOCK(imgp->proc);
                  imgp->proc->p_flag2 &= ~(P2_ASLR_ENABLE | P2_ASLR_DISABLE);
                  PROC_UNLOCK(imgp->proc);
          }
          if ((sv->sv_flags & SV_ASLR) == 0 ||
              (imgp->proc->p_flag2 & P2_ASLR_DISABLE) != 0 ||
              (fctl0 & NT_FREEBSD_FCTL_ASLR_DISABLE) != 0) {
                  KASSERT(et_dyn_addr != ET_DYN_ADDR_RAND,
                      ("et_dyn_addr == RAND and !ASLR"));
          } else if ((imgp->proc->p_flag2 & P2_ASLR_ENABLE) != 0 ||
              (__elfN(aslr_enabled) && hdr->e_type == ET_EXEC) ||
              et_dyn_addr == ET_DYN_ADDR_RAND) {
                  imgp->map_flags |= MAP_ASLR;
                  /*
                   * If user does not care about sbrk, utilize the bss
                   * grow region for mappings as well.  We can select
                   * the base for the image anywere and still not suffer
                   * from the fragmentation.
                   */
                  if (!__elfN(aslr_honor_sbrk) ||
                      (imgp->proc->p_flag2 & P2_ASLR_IGNSTART) != 0)
                          imgp->map_flags |= MAP_ASLR_IGNSTART;
          }
  
          error = exec_new_vmspace(imgp, sv);
          vmspace = imgp->proc->p_vmspace;
          map = &vmspace->vm_map;
  
          imgp->proc->p_sysent = sv;
  
          maxv = vm_map_max(map) - lim_max(td, RLIMIT_STACK);
          if (et_dyn_addr == ET_DYN_ADDR_RAND) {
                  KASSERT((map->flags & MAP_ASLR) != 0,
                      ("ET_DYN_ADDR_RAND but !MAP_ASLR"));
                  et_dyn_addr = __CONCAT(rnd_, __elfN(base))(map,
                      vm_map_min(map) + mapsz + lim_max(td, RLIMIT_DATA),
                      /* reserve half of the address space to interpreter */
                      maxv / 2, 1UL << flsl(maxalign));
          }
  
          vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
          if (error != 0)
                  goto ret;
  
          error = __elfN(load_sections)(imgp, hdr, phdr, et_dyn_addr, NULL);
          if (error != 0)
                  goto ret;
  
          error = __elfN(enforce_limits)(imgp, hdr, phdr, et_dyn_addr);
          if (error != 0)
                  goto ret;
  
          entry = (u_long)hdr->e_entry + et_dyn_addr;
  
          /*
           * We load the dynamic linker where a userland call
           * to mmap(0, ...) would put it.  The rationale behind this
           * calculation is that it leaves room for the heap to grow to
           * its maximum allowed size.
           */
          addr = round_page((vm_offset_t)vmspace->vm_daddr + lim_max(td,
              RLIMIT_DATA));
          if ((map->flags & MAP_ASLR) != 0) {
                  maxv1 = maxv / 2 + addr / 2;
                  MPASS(maxv1 >= addr);   /* No overflow */
                  map->anon_loc = __CONCAT(rnd_, __elfN(base))(map, addr, maxv1,
                      (MAXPAGESIZES > 1 && pagesizes[1] != 0) ?
                      pagesizes[1] : pagesizes[0]);
          } else {
                  map->anon_loc = addr;
          }
  
          imgp->entry_addr = entry;
  
          if (interp != NULL) {
                  VOP_UNLOCK(imgp->vp, 0);
                  if ((map->flags & MAP_ASLR) != 0) {
                          /* Assume that interpreter fits into 1/4 of AS */
                          maxv1 = maxv / 2 + addr / 2;
                          MPASS(maxv1 >= addr);   /* No overflow */
                          addr = __CONCAT(rnd_, __elfN(base))(map, addr,
                              maxv1, PAGE_SIZE);
                  }
                  error = __elfN(load_interp)(imgp, brand_info, interp, &addr,
                      &imgp->entry_addr);
                  vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
                  if (error != 0)
                          goto ret;
          } else
                  addr = et_dyn_addr;
  
          /*
           * Construct auxargs table (used by the fixup routine)
           */
          elf_auxargs = malloc(sizeof(Elf_Auxargs), M_TEMP, M_NOWAIT);
          if (elf_auxargs == NULL) {
                  VOP_UNLOCK(imgp->vp, 0);
                  elf_auxargs = malloc(sizeof(Elf_Auxargs), M_TEMP, M_WAITOK);
                  vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
          }
          elf_auxargs->execfd = -1;
          elf_auxargs->phdr = proghdr + et_dyn_addr;
          elf_auxargs->phent = hdr->e_phentsize;
          elf_auxargs->phnum = hdr->e_phnum;
          elf_auxargs->pagesz = PAGE_SIZE;
          elf_auxargs->base = addr;
          elf_auxargs->flags = 0;
          elf_auxargs->entry = entry;
          elf_auxargs->hdr_eflags = hdr->e_flags;
  
          imgp->auxargs = elf_auxargs;
          imgp->interpreted = 0;
          imgp->reloc_base = addr;
          imgp->proc->p_osrel = osrel;
          imgp->proc->p_fctl0 = fctl0;
          imgp->proc->p_elf_machine = hdr->e_machine;
          imgp->proc->p_elf_flags = hdr->e_flags;
  
  ret:
          if (free_interp)
                  free(interp, M_TEMP);
          return (error);
  }
  
  #define suword __CONCAT(suword, __ELF_WORD_SIZE)
  
  int
  __elfN(freebsd_fixup)(register_t **stack_base, struct image_params *imgp)
  {
          Elf_Auxargs *args = (Elf_Auxargs *)imgp->auxargs;
          Elf_Auxinfo *argarray, *pos;
          Elf_Addr *base, *auxbase;
          int error;
  
          base = (Elf_Addr *)*stack_base;
          auxbase = base + imgp->args->argc + 1 + imgp->args->envc + 1;
          argarray = pos = malloc(AT_COUNT * sizeof(*pos), M_TEMP,
              M_WAITOK | M_ZERO);
  
          if (args->execfd != -1)
                  AUXARGS_ENTRY(pos, AT_EXECFD, args->execfd);
          AUXARGS_ENTRY(pos, AT_PHDR, args->phdr);
          AUXARGS_ENTRY(pos, AT_PHENT, args->phent);
          AUXARGS_ENTRY(pos, AT_PHNUM, args->phnum);
          AUXARGS_ENTRY(pos, AT_PAGESZ, args->pagesz);
          AUXARGS_ENTRY(pos, AT_FLAGS, args->flags);
          AUXARGS_ENTRY(pos, AT_ENTRY, args->entry);
          AUXARGS_ENTRY(pos, AT_BASE, args->base);
          AUXARGS_ENTRY(pos, AT_EHDRFLAGS, args->hdr_eflags);
          if (imgp->execpathp != 0)
                  AUXARGS_ENTRY(pos, AT_EXECPATH, imgp->execpathp);
          AUXARGS_ENTRY(pos, AT_OSRELDATE,
              imgp->proc->p_ucred->cr_prison->pr_osreldate);
          if (imgp->canary != 0) {
                  AUXARGS_ENTRY(pos, AT_CANARY, imgp->canary);
                  AUXARGS_ENTRY(pos, AT_CANARYLEN, imgp->canarylen);
          }
          AUXARGS_ENTRY(pos, AT_NCPUS, mp_ncpus);
          if (imgp->pagesizes != 0) {
                  AUXARGS_ENTRY(pos, AT_PAGESIZES, imgp->pagesizes);
                  AUXARGS_ENTRY(pos, AT_PAGESIZESLEN, imgp->pagesizeslen);
          }
          if (imgp->sysent->sv_timekeep_base != 0) {
                  AUXARGS_ENTRY(pos, AT_TIMEKEEP,
                      imgp->sysent->sv_timekeep_base);
          }
          AUXARGS_ENTRY(pos, AT_STACKPROT, imgp->sysent->sv_shared_page_obj
              != NULL && imgp->stack_prot != 0 ? imgp->stack_prot :
              imgp->sysent->sv_stackprot);
          if (imgp->sysent->sv_hwcap != NULL)
                  AUXARGS_ENTRY(pos, AT_HWCAP, *imgp->sysent->sv_hwcap);
          if (imgp->sysent->sv_hwcap2 != NULL)
                  AUXARGS_ENTRY(pos, AT_HWCAP2, *imgp->sysent->sv_hwcap2);
          AUXARGS_ENTRY(pos, AT_NULL, 0);
  
          free(imgp->auxargs, M_TEMP);
          imgp->auxargs = NULL;
          KASSERT(pos - argarray <= AT_COUNT, ("Too many auxargs"));
  
          error = copyout(argarray, auxbase, sizeof(*argarray) * AT_COUNT);
          free(argarray, M_TEMP);
          if (error != 0)
                  return (error);
  
          base--;
          if (suword(base, imgp->args->argc) == -1)
                  return (EFAULT);
          *stack_base = (register_t *)base;
          return (0);
  }
  
  /*
   * Code for generating ELF core dumps.
   */
  
  typedef void (*segment_callback)(vm_map_entry_t, void *);
  
  /* Closure for cb_put_phdr(). */
  struct phdr_closure {
          Elf_Phdr *phdr;         /* Program header to fill in */
          Elf_Off offset;         /* Offset of segment in core file */
  };
  
  /* Closure for cb_size_segment(). */
  struct sseg_closure {
          int count;              /* Count of writable segments. */
          size_t size;            /* Total size of all writable segments. */
  };
  
  typedef void (*outfunc_t)(void *, struct sbuf *, size_t *);
  
  struct note_info {
          int             type;           /* Note type. */
          outfunc_t       outfunc;        /* Output function. */
          void            *outarg;        /* Argument for the output function. */
          size_t          outsize;        /* Output size. */
          TAILQ_ENTRY(note_info) link;    /* Link to the next note info. */
  };
  
  TAILQ_HEAD(note_info_list, note_info);
  
  /* Coredump output parameters. */
  struct coredump_params {
          off_t           offset;
          struct ucred    *active_cred;
          struct ucred    *file_cred;
          struct thread   *td;
          struct vnode    *vp;
          struct compressor *comp;
  };
  
  extern int compress_user_cores;
  extern int compress_user_cores_level;
  
  static void cb_put_phdr(vm_map_entry_t, void *);
  static void cb_size_segment(vm_map_entry_t, void *);
  static int core_write(struct coredump_params *, const void *, size_t, off_t,
      enum uio_seg);
  static void each_dumpable_segment(struct thread *, segment_callback, void *);
  static int __elfN(corehdr)(struct coredump_params *, int, void *, size_t,
      struct note_info_list *, size_t);
  static void __elfN(prepare_notes)(struct thread *, struct note_info_list *,
      size_t *);
  static void __elfN(puthdr)(struct thread *, void *, size_t, int, size_t);
  static void __elfN(putnote)(struct note_info *, struct sbuf *);
  static size_t register_note(struct note_info_list *, int, outfunc_t, void *);
  static int sbuf_drain_core_output(void *, const char *, int);
  
  static void __elfN(note_fpregset)(void *, struct sbuf *, size_t *);
  static void __elfN(note_prpsinfo)(void *, struct sbuf *, size_t *);
  static void __elfN(note_prstatus)(void *, struct sbuf *, size_t *);
  static void __elfN(note_threadmd)(void *, struct sbuf *, size_t *);
  static void __elfN(note_thrmisc)(void *, struct sbuf *, size_t *);
  static void __elfN(note_ptlwpinfo)(void *, struct sbuf *, size_t *);
  static void __elfN(note_procstat_auxv)(void *, struct sbuf *, size_t *);
  static void __elfN(note_procstat_proc)(void *, struct sbuf *, size_t *);
  static void __elfN(note_procstat_psstrings)(void *, struct sbuf *, size_t *);
  static void note_procstat_files(void *, struct sbuf *, size_t *);
  static void note_procstat_groups(void *, struct sbuf *, size_t *);
  static void note_procstat_osrel(void *, struct sbuf *, size_t *);
  static void note_procstat_rlimit(void *, struct sbuf *, size_t *);
  static void note_procstat_umask(void *, struct sbuf *, size_t *);
  static void note_procstat_vmmap(void *, struct sbuf *, size_t *);
  
  /*
   * Write out a core segment to the compression stream.
   */
  static int
  compress_chunk(struct coredump_params *p, char *base, char *buf, size_t len)
  {
          size_t chunk_len;
          int error;
  
          while (len > 0) {
                  chunk_len = MIN(len, CORE_BUF_SIZE);
  
                  /*
                   * We can get EFAULT error here.
                   * In that case zero out the current chunk of the segment.
                   */
                  error = copyin(base, buf, chunk_len);
                  if (error != 0)
                          bzero(buf, chunk_len);
                  error = compressor_write(p->comp, buf, chunk_len);
                  if (error != 0)
                          break;
                  base += chunk_len;
                  len -= chunk_len;
          }
          return (error);
  }
  
  static int
  core_compressed_write(void *base, size_t len, off_t offset, void *arg)
  {
  
          return (core_write((struct coredump_params *)arg, base, len, offset,
              UIO_SYSSPACE));
  }
  
  static int
  core_write(struct coredump_params *p, const void *base, size_t len,
      off_t offset, enum uio_seg seg)
  {
  
          return (vn_rdwr_inchunks(UIO_WRITE, p->vp, __DECONST(void *, base),
              len, offset, seg, IO_UNIT | IO_DIRECT | IO_RANGELOCKED,
              p->active_cred, p->file_cred, NULL, p->td));
  }
  
  static int
  core_output(void *base, size_t len, off_t offset, struct coredump_params *p,
      void *tmpbuf)
  {
          int error;
  
          if (p->comp != NULL)
                  return (compress_chunk(p, base, tmpbuf, len));
  
          /*
           * EFAULT is a non-fatal error that we can get, for example,
           * if the segment is backed by a file but extends beyond its
           * end.
           */
          error = core_write(p, base, len, offset, UIO_USERSPACE);
          if (error == EFAULT) {
                  log(LOG_WARNING, "Failed to fully fault in a core file segment "
                      "at VA %p with size 0x%zx to be written at offset 0x%jx "
                      "for process %s\n", base, len, offset, curproc->p_comm);
  
                  /*
                   * Write a "real" zero byte at the end of the target region
                   * in the case this is the last segment.
                   * The intermediate space will be implicitly zero-filled.
                   */
                  error = core_write(p, zero_region, 1, offset + len - 1,
                      UIO_SYSSPACE);
          }
          return (error);
  }
  
  /*
   * Drain into a core file.
   */
  static int
  sbuf_drain_core_output(void *arg, const char *data, int len)
  {
          struct coredump_params *p;
          int error, locked;
  
          p = (struct coredump_params *)arg;
  
          /*
           * Some kern_proc out routines that print to this sbuf may
           * call us with the process lock held. Draining with the
           * non-sleepable lock held is unsafe. The lock is needed for
           * those routines when dumping a live process. In our case we
           * can safely release the lock before draining and acquire
           * again after.
           */
          locked = PROC_LOCKED(p->td->td_proc);
          if (locked)
                  PROC_UNLOCK(p->td->td_proc);
          if (p->comp != NULL)
                  error = compressor_write(p->comp, __DECONST(char *, data), len);
          else
                  error = core_write(p, __DECONST(void *, data), len, p->offset,
                      UIO_SYSSPACE);
          if (locked)
                  PROC_LOCK(p->td->td_proc);
          if (error != 0)
                  return (-error);
          p->offset += len;
          return (len);
  }
  
  int
  __elfN(coredump)(struct thread *td, struct vnode *vp, off_t limit, int flags)
  {
          struct ucred *cred = td->td_ucred;
          int error = 0;
          struct sseg_closure seginfo;
          struct note_info_list notelst;
          struct coredump_params params;
          struct note_info *ninfo;
          void *hdr, *tmpbuf;
          size_t hdrsize, notesz, coresize;
  
          hdr = NULL;
          tmpbuf = NULL;
          TAILQ_INIT(&notelst);
  
          /* Size the program segments. */
          seginfo.count = 0;
          seginfo.size = 0;
          each_dumpable_segment(td, cb_size_segment, &seginfo);
  
          /*
           * Collect info about the core file header area.
           */
          hdrsize = sizeof(Elf_Ehdr) + sizeof(Elf_Phdr) * (1 + seginfo.count);
          if (seginfo.count + 1 >= PN_XNUM)
                  hdrsize += sizeof(Elf_Shdr);
          __elfN(prepare_notes)(td, &notelst, &notesz);
          coresize = round_page(hdrsize + notesz) + seginfo.size;
  
          /* Set up core dump parameters. */
          params.offset = 0;
          params.active_cred = cred;
          params.file_cred = NOCRED;
          params.td = td;
          params.vp = vp;
          params.comp = NULL;
  
  #ifdef RACCT
          if (racct_enable) {
                  PROC_LOCK(td->td_proc);
                  error = racct_add(td->td_proc, RACCT_CORE, coresize);
                  PROC_UNLOCK(td->td_proc);
                  if (error != 0) {
                          error = EFAULT;
                          goto done;
                  }
          }
  #endif
          if (coresize >= limit) {
                  error = EFAULT;
                  goto done;
          }
  
          /* Create a compression stream if necessary. */
          if (compress_user_cores != 0) {
                  params.comp = compressor_init(core_compressed_write,
                      compress_user_cores, CORE_BUF_SIZE,
                      compress_user_cores_level, &params);
                  if (params.comp == NULL) {
                          error = EFAULT;
                          goto done;
                  }
                  tmpbuf = malloc(CORE_BUF_SIZE, M_TEMP, M_WAITOK | M_ZERO);
          }
  
          /*
           * Allocate memory for building the header, fill it up,
           * and write it out following the notes.
           */
          hdr = malloc(hdrsize, M_TEMP, M_WAITOK);
          error = __elfN(corehdr)(&params, seginfo.count, hdr, hdrsize, &notelst,
              notesz);
  
          /* Write the contents of all of the writable segments. */
          if (error == 0) {
                  Elf_Phdr *php;
                  off_t offset;
                  int i;
  
                  php = (Elf_Phdr *)((char *)hdr + sizeof(Elf_Ehdr)) + 1;
                  offset = round_page(hdrsize + notesz);
                  for (i = 0; i < seginfo.count; i++) {
                          error = core_output((caddr_t)(uintptr_t)php->p_vaddr,
                              php->p_filesz, offset, &params, tmpbuf);
                          if (error != 0)
                                  break;
                          offset += php->p_filesz;
                          php++;
                  }
                  if (error == 0 && params.comp != NULL)
                          error = compressor_flush(params.comp);
          }
          if (error) {
                  log(LOG_WARNING,
                      "Failed to write core file for process %s (error %d)\n",
                      curproc->p_comm, error);
          }
  
  done:
          free(tmpbuf, M_TEMP);
          if (params.comp != NULL)
                  compressor_fini(params.comp);
          while ((ninfo = TAILQ_FIRST(&notelst)) != NULL) {
                  TAILQ_REMOVE(&notelst, ninfo, link);
                  free(ninfo, M_TEMP);
          }
          if (hdr != NULL)
                  free(hdr, M_TEMP);
  
          return (error);
  }
  
  /*
   * A callback for each_dumpable_segment() to write out the segment's
   * program header entry.
   */
  static void
  cb_put_phdr(vm_map_entry_t entry, void *closure)
  {
          struct phdr_closure *phc = (struct phdr_closure *)closure;
          Elf_Phdr *phdr = phc->phdr;
  
          phc->offset = round_page(phc->offset);
  
          phdr->p_type = PT_LOAD;
          phdr->p_offset = phc->offset;
          phdr->p_vaddr = entry->start;
          phdr->p_paddr = 0;
          phdr->p_filesz = phdr->p_memsz = entry->end - entry->start;
          phdr->p_align = PAGE_SIZE;
          phdr->p_flags = __elfN(untrans_prot)(entry->protection);
  
          phc->offset += phdr->p_filesz;
          phc->phdr++;
  }
  
  /*
   * A callback for each_dumpable_segment() to gather information about
   * the number of segments and their total size.
   */
  static void
  cb_size_segment(vm_map_entry_t entry, void *closure)
  {
          struct sseg_closure *ssc = (struct sseg_closure *)closure;
  
          ssc->count++;
          ssc->size += entry->end - entry->start;
  }
  
  /*
   * For each writable segment in the process's memory map, call the given
   * function with a pointer to the map entry and some arbitrary
   * caller-supplied data.
   */
  static void
  each_dumpable_segment(struct thread *td, segment_callback func, void *closure)
  {
          struct proc *p = td->td_proc;
          vm_map_t map = &p->p_vmspace->vm_map;
          vm_map_entry_t entry;
          vm_object_t backing_object, object;
          bool ignore_entry;
  
          vm_map_lock_read(map);
          for (entry = map->header.next; entry != &map->header;
              entry = entry->next) {
                  /*
                   * Don't dump inaccessible mappings, deal with legacy
                   * coredump mode.
                   *
                   * Note that read-only segments related to the elf binary
                   * are marked MAP_ENTRY_NOCOREDUMP now so we no longer
                   * need to arbitrarily ignore such segments.
                   */
                  if (elf_legacy_coredump) {
                          if ((entry->protection & VM_PROT_RW) != VM_PROT_RW)
                                  continue;
                  } else {
                          if ((entry->protection & VM_PROT_ALL) == 0)
                                  continue;
                  }
  
                  /*
                   * Dont include memory segment in the coredump if
                   * MAP_NOCORE is set in mmap(2) or MADV_NOCORE in
                   * madvise(2).  Do not dump submaps (i.e. parts of the
                   * kernel map).
                   */
                  if (entry->eflags & (MAP_ENTRY_NOCOREDUMP|MAP_ENTRY_IS_SUB_MAP))
                          continue;
  
                  if ((object = entry->object.vm_object) == NULL)
                          continue;
  
                  /* Ignore memory-mapped devices and such things. */
                  VM_OBJECT_RLOCK(object);
                  while ((backing_object = object->backing_object) != NULL) {
                          VM_OBJECT_RLOCK(backing_object);
                          VM_OBJECT_RUNLOCK(object);
                          object = backing_object;
                  }
                  ignore_entry = (object->flags & OBJ_FICTITIOUS) != 0;
                  VM_OBJECT_RUNLOCK(object);
                  if (ignore_entry)
                          continue;
  
                  (*func)(entry, closure);
          }
          vm_map_unlock_read(map);
  }
  
  /*
   * Write the core file header to the file, including padding up to
   * the page boundary.
   */
  static int
  __elfN(corehdr)(struct coredump_params *p, int numsegs, void *hdr,
      size_t hdrsize, struct note_info_list *notelst, size_t notesz)
  {
          struct note_info *ninfo;
          struct sbuf *sb;
          int error;
  
          /* Fill in the header. */
          bzero(hdr, hdrsize);
          __elfN(puthdr)(p->td, hdr, hdrsize, numsegs, notesz);
  
          sb = sbuf_new(NULL, NULL, CORE_BUF_SIZE, SBUF_FIXEDLEN);
          sbuf_set_drain(sb, sbuf_drain_core_output, p);
          sbuf_start_section(sb, NULL);
          sbuf_bcat(sb, hdr, hdrsize);
          TAILQ_FOREACH(ninfo, notelst, link)
              __elfN(putnote)(ninfo, sb);
          /* Align up to a page boundary for the program segments. */
          sbuf_end_section(sb, -1, PAGE_SIZE, 0);
          error = sbuf_finish(sb);
          sbuf_delete(sb);
  
          return (error);
  }
  
  static void
  __elfN(prepare_notes)(struct thread *td, struct note_info_list *list,
      size_t *sizep)
  {
          struct proc *p;
          struct thread *thr;
          size_t size;
  
          p = td->td_proc;
          size = 0;
  
          size += register_note(list, NT_PRPSINFO, __elfN(note_prpsinfo), p);
  
          /*
           * To have the debugger select the right thread (LWP) as the initial
           * thread, we dump the state of the thread passed to us in td first.
           * This is the thread that causes the core dump and thus likely to
           * be the right thread one wants to have selected in the debugger.
           */
          thr = td;
          while (thr != NULL) {
                  size += register_note(list, NT_PRSTATUS,
                      __elfN(note_prstatus), thr);
                  size += register_note(list, NT_FPREGSET,
                      __elfN(note_fpregset), thr);
                  size += register_note(list, NT_THRMISC,
                      __elfN(note_thrmisc), thr);
                  size += register_note(list, NT_PTLWPINFO,
                      __elfN(note_ptlwpinfo), thr);
                  size += register_note(list, -1,
                      __elfN(note_threadmd), thr);
  
                  thr = (thr == td) ? TAILQ_FIRST(&p->p_threads) :
                      TAILQ_NEXT(thr, td_plist);
                  if (thr == td)
                          thr = TAILQ_NEXT(thr, td_plist);
          }
  
          size += register_note(list, NT_PROCSTAT_PROC,
              __elfN(note_procstat_proc), p);
          size += register_note(list, NT_PROCSTAT_FILES,
              note_procstat_files, p);
          size += register_note(list, NT_PROCSTAT_VMMAP,
              note_procstat_vmmap, p);
          size += register_note(list, NT_PROCSTAT_GROUPS,
              note_procstat_groups, p);
          size += register_note(list, NT_PROCSTAT_UMASK,
              note_procstat_umask, p);
          size += register_note(list, NT_PROCSTAT_RLIMIT,
              note_procstat_rlimit, p);
          size += register_note(list, NT_PROCSTAT_OSREL,
              note_procstat_osrel, p);
          size += register_note(list, NT_PROCSTAT_PSSTRINGS,
              __elfN(note_procstat_psstrings), p);
          size += register_note(list, NT_PROCSTAT_AUXV,
              __elfN(note_procstat_auxv), p);
  
          *sizep = size;
  }
  
  static void
  __elfN(puthdr)(struct thread *td, void *hdr, size_t hdrsize, int numsegs,
      size_t notesz)
  {
          Elf_Ehdr *ehdr;
          Elf_Phdr *phdr;
          Elf_Shdr *shdr;
          struct phdr_closure phc;
  
          ehdr = (Elf_Ehdr *)hdr;
  
          ehdr->e_ident[EI_MAG0] = ELFMAG0;
          ehdr->e_ident[EI_MAG1] = ELFMAG1;
          ehdr->e_ident[EI_MAG2] = ELFMAG2;
          ehdr->e_ident[EI_MAG3] = ELFMAG3;
          ehdr->e_ident[EI_CLASS] = ELF_CLASS;
          ehdr->e_ident[EI_DATA] = ELF_DATA;
          ehdr->e_ident[EI_VERSION] = EV_CURRENT;
          ehdr->e_ident[EI_OSABI] = ELFOSABI_FREEBSD;
          ehdr->e_ident[EI_ABIVERSION] = 0;
          ehdr->e_ident[EI_PAD] = 0;
          ehdr->e_type = ET_CORE;
          ehdr->e_machine = td->td_proc->p_elf_machine;
          ehdr->e_version = EV_CURRENT;
          ehdr->e_entry = 0;
          ehdr->e_phoff = sizeof(Elf_Ehdr);
          ehdr->e_flags = td->td_proc->p_elf_flags;
          ehdr->e_ehsize = sizeof(Elf_Ehdr);
          ehdr->e_phentsize = sizeof(Elf_Phdr);
          ehdr->e_shentsize = sizeof(Elf_Shdr);
          ehdr->e_shstrndx = SHN_UNDEF;
          if (numsegs + 1 < PN_XNUM) {
                  ehdr->e_phnum = numsegs + 1;
                  ehdr->e_shnum = 0;
          } else {
                  ehdr->e_phnum = PN_XNUM;
                  ehdr->e_shnum = 1;
  
                  ehdr->e_shoff = ehdr->e_phoff +
                      (numsegs + 1) * ehdr->e_phentsize;
                  KASSERT(ehdr->e_shoff == hdrsize - sizeof(Elf_Shdr),
                      ("e_shoff: %zu, hdrsize - shdr: %zu",
                       (size_t)ehdr->e_shoff, hdrsize - sizeof(Elf_Shdr)));
  
                  shdr = (Elf_Shdr *)((char *)hdr + ehdr->e_shoff);
                  memset(shdr, 0, sizeof(*shdr));
                  /*
                   * A special first section is used to hold large segment and
                   * section counts.  This was proposed by Sun Microsystems in
                   * Solaris and has been adopted by Linux; the standard ELF
                   * tools are already familiar with the technique.
                   *
                   * See table 7-7 of the Solaris "Linker and Libraries Guide"
                   * (or 12-7 depending on the version of the document) for more
                   * details.
                   */
                  shdr->sh_type = SHT_NULL;
                  shdr->sh_size = ehdr->e_shnum;
                  shdr->sh_link = ehdr->e_shstrndx;
                  shdr->sh_info = numsegs + 1;
          }
  
          /*
           * Fill in the program header entries.
           */
          phdr = (Elf_Phdr *)((char *)hdr + ehdr->e_phoff);
  
          /* The note segement. */
          phdr->p_type = PT_NOTE;
          phdr->p_offset = hdrsize;
          phdr->p_vaddr = 0;
          phdr->p_paddr = 0;
          phdr->p_filesz = notesz;
          phdr->p_memsz = 0;
          phdr->p_flags = PF_R;
          phdr->p_align = ELF_NOTE_ROUNDSIZE;
          phdr++;
  
          /* All the writable segments from the program. */
          phc.phdr = phdr;
          phc.offset = round_page(hdrsize + notesz);
          each_dumpable_segment(td, cb_put_phdr, &phc);
  }
  
  static size_t
  register_note(struct note_info_list *list, int type, outfunc_t out, void *arg)
  {
          struct note_info *ninfo;
          size_t size, notesize;
  
          size = 0;
          out(arg, NULL, &size);
          ninfo = malloc(sizeof(*ninfo), M_TEMP, M_ZERO | M_WAITOK);
          ninfo->type = type;
          ninfo->outfunc = out;
          ninfo->outarg = arg;
          ninfo->outsize = size;
          TAILQ_INSERT_TAIL(list, ninfo, link);
  
          if (type == -1)
                  return (size);
  
          notesize = sizeof(Elf_Note) +           /* note header */
              roundup2(sizeof(FREEBSD_ABI_VENDOR), ELF_NOTE_ROUNDSIZE) +
                                                  /* note name */
              roundup2(size, ELF_NOTE_ROUNDSIZE); /* note description */
  
          return (notesize);
  }
  
  static size_t
  append_note_data(const void *src, void *dst, size_t len)
  {
          size_t padded_len;
  
          padded_len = roundup2(len, ELF_NOTE_ROUNDSIZE);
          if (dst != NULL) {
                  bcopy(src, dst, len);
                  bzero((char *)dst + len, padded_len - len);
          }
          return (padded_len);
  }
  
  size_t
  __elfN(populate_note)(int type, void *src, void *dst, size_t size, void **descp)
  {
          Elf_Note *note;
          char *buf;
          size_t notesize;
  
          buf = dst;
          if (buf != NULL) {
                  note = (Elf_Note *)buf;
                  note->n_namesz = sizeof(FREEBSD_ABI_VENDOR);
                  note->n_descsz = size;
                  note->n_type = type;
                  buf += sizeof(*note);
                  buf += append_note_data(FREEBSD_ABI_VENDOR, buf,
                      sizeof(FREEBSD_ABI_VENDOR));
                  append_note_data(src, buf, size);
                  if (descp != NULL)
                          *descp = buf;
          }
  
          notesize = sizeof(Elf_Note) +           /* note header */
              roundup2(sizeof(FREEBSD_ABI_VENDOR), ELF_NOTE_ROUNDSIZE) +
                                                  /* note name */
              roundup2(size, ELF_NOTE_ROUNDSIZE); /* note description */
  
          return (notesize);
  }
  
  static void
  __elfN(putnote)(struct note_info *ninfo, struct sbuf *sb)
  {
          Elf_Note note;
          ssize_t old_len, sect_len;
          size_t new_len, descsz, i;
  
          if (ninfo->type == -1) {
                  ninfo->outfunc(ninfo->outarg, sb, &ninfo->outsize);
                  return;
          }
  
          note.n_namesz = sizeof(FREEBSD_ABI_VENDOR);
          note.n_descsz = ninfo->outsize;
          note.n_type = ninfo->type;
  
          sbuf_bcat(sb, &note, sizeof(note));
          sbuf_start_section(sb, &old_len);
          sbuf_bcat(sb, FREEBSD_ABI_VENDOR, sizeof(FREEBSD_ABI_VENDOR));
          sbuf_end_section(sb, old_len, ELF_NOTE_ROUNDSIZE, 0);
          if (note.n_descsz == 0)
                  return;
          sbuf_start_section(sb, &old_len);
          ninfo->outfunc(ninfo->outarg, sb, &ninfo->outsize);
          sect_len = sbuf_end_section(sb, old_len, ELF_NOTE_ROUNDSIZE, 0);
          if (sect_len < 0)
                  return;
  
          new_len = (size_t)sect_len;
          descsz = roundup(note.n_descsz, ELF_NOTE_ROUNDSIZE);
          if (new_len < descsz) {
                  /*
                   * It is expected that individual note emitters will correctly
                   * predict their expected output size and fill up to that size
                   * themselves, padding in a format-specific way if needed.
                   * However, in case they don't, just do it here with zeros.
                   */
                  for (i = 0; i < descsz - new_len; i++)
                          sbuf_putc(sb, 0);
          } else if (new_len > descsz) {
                  /*
                   * We can't always truncate sb -- we may have drained some
                   * of it already.
                   */
                  KASSERT(new_len == descsz, ("%s: Note type %u changed as we "
                      "read it (%zu > %zu).  Since it is longer than "
                      "expected, this coredump's notes are corrupt.  THIS "
                      "IS A BUG in the note_procstat routine for type %u.\n",
                      __func__, (unsigned)note.n_type, new_len, descsz,
                      (unsigned)note.n_type));
          }
  }
  
  /*
   * Miscellaneous note out functions.
   */
  
  #if defined(COMPAT_FREEBSD32) && __ELF_WORD_SIZE == 32
  #include <compat/freebsd32/freebsd32.h>
  #include <compat/freebsd32/freebsd32_signal.h>
  
  typedef struct prstatus32 elf_prstatus_t;
  typedef struct prpsinfo32 elf_prpsinfo_t;
  typedef struct fpreg32 elf_prfpregset_t;
  typedef struct fpreg32 elf_fpregset_t;
  typedef struct reg32 elf_gregset_t;
  typedef struct thrmisc32 elf_thrmisc_t;
  #define ELF_KERN_PROC_MASK      KERN_PROC_MASK32
  typedef struct kinfo_proc32 elf_kinfo_proc_t;
  typedef uint32_t elf_ps_strings_t;
  #else
  typedef prstatus_t elf_prstatus_t;
  typedef prpsinfo_t elf_prpsinfo_t;
  typedef prfpregset_t elf_prfpregset_t;
  typedef prfpregset_t elf_fpregset_t;
  typedef gregset_t elf_gregset_t;
  typedef thrmisc_t elf_thrmisc_t;
  #define ELF_KERN_PROC_MASK      0
  typedef struct kinfo_proc elf_kinfo_proc_t;
  typedef vm_offset_t elf_ps_strings_t;
  #endif
  
  static void
  __elfN(note_prpsinfo)(void *arg, struct sbuf *sb, size_t *sizep)
  {
          struct sbuf sbarg;
          size_t len;
          char *cp, *end;
          struct proc *p;
          elf_prpsinfo_t *psinfo;
          int error;
  
          p = (struct proc *)arg;
          if (sb != NULL) {
                  KASSERT(*sizep == sizeof(*psinfo), ("invalid size"));
                  psinfo = malloc(sizeof(*psinfo), M_TEMP, M_ZERO | M_WAITOK);
                  psinfo->pr_version = PRPSINFO_VERSION;
                  psinfo->pr_psinfosz = sizeof(elf_prpsinfo_t);
                  strlcpy(psinfo->pr_fname, p->p_comm, sizeof(psinfo->pr_fname));
                  PROC_LOCK(p);
                  if (p->p_args != NULL) {
                          len = sizeof(psinfo->pr_psargs) - 1;
                          if (len > p->p_args->ar_length)
                                  len = p->p_args->ar_length;
                          memcpy(psinfo->pr_psargs, p->p_args->ar_args, len);
                          PROC_UNLOCK(p);
                          error = 0;
                  } else {
                          _PHOLD(p);
                          PROC_UNLOCK(p);
                          sbuf_new(&sbarg, psinfo->pr_psargs,
                              sizeof(psinfo->pr_psargs), SBUF_FIXEDLEN);
                          error = proc_getargv(curthread, p, &sbarg);
                          PRELE(p);
                          if (sbuf_finish(&sbarg) == 0) {
                                  len = sbuf_len(&sbarg);
                                  if (len > 0)
                                          len--;
                          } else {
                                  len = sizeof(psinfo->pr_psargs) - 1;
                          }
                          sbuf_delete(&sbarg);
                  }
                  if (error != 0 || len == 0 || (ssize_t)len == -1)
                          strlcpy(psinfo->pr_psargs, p->p_comm,
                              sizeof(psinfo->pr_psargs));
                  else {
                          KASSERT(len < sizeof(psinfo->pr_psargs),
                              ("len is too long: %zu vs %zu", len,
                              sizeof(psinfo->pr_psargs)));
                          cp = psinfo->pr_psargs;
                          end = cp + len - 1;
                          for (;;) {
                                  cp = memchr(cp, '\0', end - cp);
                                  if (cp == NULL)
                                          break;
                                  *cp = ' ';
                          }
                  }
                  psinfo->pr_pid = p->p_pid;
                  sbuf_bcat(sb, psinfo, sizeof(*psinfo));
                  free(psinfo, M_TEMP);
          }
          *sizep = sizeof(*psinfo);
  }
  
  static void
  __elfN(note_prstatus)(void *arg, struct sbuf *sb, size_t *sizep)
  {
          struct thread *td;
          elf_prstatus_t *status;
  
          td = (struct thread *)arg;
          if (sb != NULL) {
                  KASSERT(*sizep == sizeof(*status), ("invalid size"));
                  status = malloc(sizeof(*status), M_TEMP, M_ZERO | M_WAITOK);
                  status->pr_version = PRSTATUS_VERSION;
                  status->pr_statussz = sizeof(elf_prstatus_t);
                  status->pr_gregsetsz = sizeof(elf_gregset_t);
                  status->pr_fpregsetsz = sizeof(elf_fpregset_t);
                  status->pr_osreldate = osreldate;
                  status->pr_cursig = td->td_proc->p_sig;
                  status->pr_pid = td->td_tid;
  #if defined(COMPAT_FREEBSD32) && __ELF_WORD_SIZE == 32
                  fill_regs32(td, &status->pr_reg);
  #else
                  fill_regs(td, &status->pr_reg);
  #endif
                  sbuf_bcat(sb, status, sizeof(*status));
                  free(status, M_TEMP);
          }
          *sizep = sizeof(*status);
  }
  
  static void
  __elfN(note_fpregset)(void *arg, struct sbuf *sb, size_t *sizep)
  {
          struct thread *td;
          elf_prfpregset_t *fpregset;
  
          td = (struct thread *)arg;
          if (sb != NULL) {
                  KASSERT(*sizep == sizeof(*fpregset), ("invalid size"));
                  fpregset = malloc(sizeof(*fpregset), M_TEMP, M_ZERO | M_WAITOK);
  #if defined(COMPAT_FREEBSD32) && __ELF_WORD_SIZE == 32
                  fill_fpregs32(td, fpregset);
  #else
                  fill_fpregs(td, fpregset);
  #endif
                  sbuf_bcat(sb, fpregset, sizeof(*fpregset));
                  free(fpregset, M_TEMP);
          }
          *sizep = sizeof(*fpregset);
  }
  
  static void
  __elfN(note_thrmisc)(void *arg, struct sbuf *sb, size_t *sizep)
  {
          struct thread *td;
          elf_thrmisc_t thrmisc;
  
          td = (struct thread *)arg;
          if (sb != NULL) {
                  KASSERT(*sizep == sizeof(thrmisc), ("invalid size"));
                  bzero(&thrmisc, sizeof(thrmisc));
                  strcpy(thrmisc.pr_tname, td->td_name);
                  sbuf_bcat(sb, &thrmisc, sizeof(thrmisc));
          }
          *sizep = sizeof(thrmisc);
  }
  
  static void
  __elfN(note_ptlwpinfo)(void *arg, struct sbuf *sb, size_t *sizep)
  {
          struct thread *td;
          size_t size;
          int structsize;
  #if defined(COMPAT_FREEBSD32) && __ELF_WORD_SIZE == 32
          struct ptrace_lwpinfo32 pl;
  #else
          struct ptrace_lwpinfo pl;
  #endif
  
          td = (struct thread *)arg;
          size = sizeof(structsize) + sizeof(pl);
          if (sb != NULL) {
                  KASSERT(*sizep == size, ("invalid size"));
                  structsize = sizeof(pl);
                  sbuf_bcat(sb, &structsize, sizeof(structsize));
                  bzero(&pl, sizeof(pl));
                  pl.pl_lwpid = td->td_tid;
                  pl.pl_event = PL_EVENT_NONE;
                  pl.pl_sigmask = td->td_sigmask;
                  pl.pl_siglist = td->td_siglist;
                  if (td->td_si.si_signo != 0) {
                          pl.pl_event = PL_EVENT_SIGNAL;
                          pl.pl_flags |= PL_FLAG_SI;
  #if defined(COMPAT_FREEBSD32) && __ELF_WORD_SIZE == 32
                          siginfo_to_siginfo32(&td->td_si, &pl.pl_siginfo);
  #else
                          pl.pl_siginfo = td->td_si;
  #endif
                  }
                  strcpy(pl.pl_tdname, td->td_name);
                  /* XXX TODO: supply more information in struct ptrace_lwpinfo*/
                  sbuf_bcat(sb, &pl, sizeof(pl));
          }
          *sizep = size;
  }
  
  /*
   * Allow for MD specific notes, as well as any MD
   * specific preparations for writing MI notes.
   */
  static void
  __elfN(note_threadmd)(void *arg, struct sbuf *sb, size_t *sizep)
  {
          struct thread *td;
          void *buf;
          size_t size;
  
          td = (struct thread *)arg;
          size = *sizep;
          if (size != 0 && sb != NULL)
                  buf = malloc(size, M_TEMP, M_ZERO | M_WAITOK);
          else
                  buf = NULL;
          size = 0;
          __elfN(dump_thread)(td, buf, &size);
          KASSERT(sb == NULL || *sizep == size, ("invalid size"));
          if (size != 0 && sb != NULL)
                  sbuf_bcat(sb, buf, size);
          free(buf, M_TEMP);
          *sizep = size;
  }
  
  #ifdef KINFO_PROC_SIZE
  CTASSERT(sizeof(struct kinfo_proc) == KINFO_PROC_SIZE);
  #endif
  
  static void
  __elfN(note_procstat_proc)(void *arg, struct sbuf *sb, size_t *sizep)
  {
          struct proc *p;
          size_t size;
          int structsize;
  
          p = (struct proc *)arg;
          size = sizeof(structsize) + p->p_numthreads *
              sizeof(elf_kinfo_proc_t);
  
          if (sb != NULL) {
                  KASSERT(*sizep == size, ("invalid size"));
                  structsize = sizeof(elf_kinfo_proc_t);
                  sbuf_bcat(sb, &structsize, sizeof(structsize));
                  sx_slock(&proctree_lock);
                  PROC_LOCK(p);
                  kern_proc_out(p, sb, ELF_KERN_PROC_MASK);
                  sx_sunlock(&proctree_lock);
          }
          *sizep = size;
  }
  
  #ifdef KINFO_FILE_SIZE
  CTASSERT(sizeof(struct kinfo_file) == KINFO_FILE_SIZE);
  #endif
  
  static void
  note_procstat_files(void *arg, struct sbuf *sb, size_t *sizep)
  {
          struct proc *p;
          size_t size, sect_sz, i;
          ssize_t start_len, sect_len;
          int structsize, filedesc_flags;
  
          if (coredump_pack_fileinfo)
                  filedesc_flags = KERN_FILEDESC_PACK_KINFO;
          else
                  filedesc_flags = 0;
  
          p = (struct proc *)arg;
          structsize = sizeof(struct kinfo_file);
          if (sb == NULL) {
                  size = 0;
                  sb = sbuf_new(NULL, NULL, 128, SBUF_FIXEDLEN);
                  sbuf_set_drain(sb, sbuf_count_drain, &size);
                  sbuf_bcat(sb, &structsize, sizeof(structsize));
                  PROC_LOCK(p);
                  kern_proc_filedesc_out(p, sb, -1, filedesc_flags);
                  sbuf_finish(sb);
                  sbuf_delete(sb);
                  *sizep = size;
          } else {
                  sbuf_start_section(sb, &start_len);
  
                  sbuf_bcat(sb, &structsize, sizeof(structsize));
                  PROC_LOCK(p);
                  kern_proc_filedesc_out(p, sb, *sizep - sizeof(structsize),
                      filedesc_flags);
  
                  sect_len = sbuf_end_section(sb, start_len, 0, 0);
                  if (sect_len < 0)
                          return;
                  sect_sz = sect_len;
  
                  KASSERT(sect_sz <= *sizep,
                      ("kern_proc_filedesc_out did not respect maxlen; "
                       "requested %zu, got %zu", *sizep - sizeof(structsize),
                       sect_sz - sizeof(structsize)));
  
                  for (i = 0; i < *sizep - sect_sz && sb->s_error == 0; i++)
                          sbuf_putc(sb, 0);
          }
  }
  
  #ifdef KINFO_VMENTRY_SIZE
  CTASSERT(sizeof(struct kinfo_vmentry) == KINFO_VMENTRY_SIZE);
  #endif
  
  static void
  note_procstat_vmmap(void *arg, struct sbuf *sb, size_t *sizep)
  {
          struct proc *p;
          size_t size;
          int structsize, vmmap_flags;
  
          if (coredump_pack_vmmapinfo)
                  vmmap_flags = KERN_VMMAP_PACK_KINFO;
          else
                  vmmap_flags = 0;
  
          p = (struct proc *)arg;
          structsize = sizeof(struct kinfo_vmentry);
          if (sb == NULL) {
                  size = 0;
                  sb = sbuf_new(NULL, NULL, 128, SBUF_FIXEDLEN);
                  sbuf_set_drain(sb, sbuf_count_drain, &size);
                  sbuf_bcat(sb, &structsize, sizeof(structsize));
                  PROC_LOCK(p);
                  kern_proc_vmmap_out(p, sb, -1, vmmap_flags);
                  sbuf_finish(sb);
                  sbuf_delete(sb);
                  *sizep = size;
          } else {
                  sbuf_bcat(sb, &structsize, sizeof(structsize));
                  PROC_LOCK(p);
                  kern_proc_vmmap_out(p, sb, *sizep - sizeof(structsize),
                      vmmap_flags);
          }
  }
  
  static void
  note_procstat_groups(void *arg, struct sbuf *sb, size_t *sizep)
  {
          struct proc *p;
          size_t size;
          int structsize;
  
          p = (struct proc *)arg;
          size = sizeof(structsize) + p->p_ucred->cr_ngroups * sizeof(gid_t);
          if (sb != NULL) {
                  KASSERT(*sizep == size, ("invalid size"));
                  structsize = sizeof(gid_t);
                  sbuf_bcat(sb, &structsize, sizeof(structsize));
                  sbuf_bcat(sb, p->p_ucred->cr_groups, p->p_ucred->cr_ngroups *
                      sizeof(gid_t));
          }
          *sizep = size;
  }
  
  static void
  note_procstat_umask(void *arg, struct sbuf *sb, size_t *sizep)
  {
          struct proc *p;
          size_t size;
          int structsize;
  
          p = (struct proc *)arg;
          size = sizeof(structsize) + sizeof(p->p_fd->fd_cmask);
          if (sb != NULL) {
                  KASSERT(*sizep == size, ("invalid size"));
                  structsize = sizeof(p->p_fd->fd_cmask);
                  sbuf_bcat(sb, &structsize, sizeof(structsize));
                  sbuf_bcat(sb, &p->p_fd->fd_cmask, sizeof(p->p_fd->fd_cmask));
          }
          *sizep = size;
  }
  
  static void
  note_procstat_rlimit(void *arg, struct sbuf *sb, size_t *sizep)
  {
          struct proc *p;
          struct rlimit rlim[RLIM_NLIMITS];
          size_t size;
          int structsize, i;
  
          p = (struct proc *)arg;
          size = sizeof(structsize) + sizeof(rlim);
          if (sb != NULL) {
                  KASSERT(*sizep == size, ("invalid size"));
                  structsize = sizeof(rlim);
                  sbuf_bcat(sb, &structsize, sizeof(structsize));
                  PROC_LOCK(p);
                  for (i = 0; i < RLIM_NLIMITS; i++)
                          lim_rlimit_proc(p, i, &rlim[i]);
                  PROC_UNLOCK(p);
                  sbuf_bcat(sb, rlim, sizeof(rlim));
          }
          *sizep = size;
  }
  
  static void
  note_procstat_osrel(void *arg, struct sbuf *sb, size_t *sizep)
  {
          struct proc *p;
          size_t size;
          int structsize;
  
          p = (struct proc *)arg;
          size = sizeof(structsize) + sizeof(p->p_osrel);
          if (sb != NULL) {
                  KASSERT(*sizep == size, ("invalid size"));
                  structsize = sizeof(p->p_osrel);
                  sbuf_bcat(sb, &structsize, sizeof(structsize));
                  sbuf_bcat(sb, &p->p_osrel, sizeof(p->p_osrel));
          }
          *sizep = size;
  }
  
  static void
  __elfN(note_procstat_psstrings)(void *arg, struct sbuf *sb, size_t *sizep)
  {
          struct proc *p;
          elf_ps_strings_t ps_strings;
          size_t size;
          int structsize;
  
          p = (struct proc *)arg;
          size = sizeof(structsize) + sizeof(ps_strings);
          if (sb != NULL) {
                  KASSERT(*sizep == size, ("invalid size"));
                  structsize = sizeof(ps_strings);
  #if defined(COMPAT_FREEBSD32) && __ELF_WORD_SIZE == 32
                  ps_strings = PTROUT(p->p_sysent->sv_psstrings);
  #else
                  ps_strings = p->p_sysent->sv_psstrings;
  #endif
                  sbuf_bcat(sb, &structsize, sizeof(structsize));
                  sbuf_bcat(sb, &ps_strings, sizeof(ps_strings));
          }
          *sizep = size;
  }
  
  static void
  __elfN(note_procstat_auxv)(void *arg, struct sbuf *sb, size_t *sizep)
  {
          struct proc *p;
          size_t size;
          int structsize;
  
          p = (struct proc *)arg;
          if (sb == NULL) {
                  size = 0;
                  sb = sbuf_new(NULL, NULL, 128, SBUF_FIXEDLEN);
                  sbuf_set_drain(sb, sbuf_count_drain, &size);
                  sbuf_bcat(sb, &structsize, sizeof(structsize));
                  PHOLD(p);
                  proc_getauxv(curthread, p, sb);
                  PRELE(p);
                  sbuf_finish(sb);
                  sbuf_delete(sb);
                  *sizep = size;
          } else {
                  structsize = sizeof(Elf_Auxinfo);
                  sbuf_bcat(sb, &structsize, sizeof(structsize));
                  PHOLD(p);
                  proc_getauxv(curthread, p, sb);
                  PRELE(p);
          }
  }
  
  static boolean_t
  __elfN(parse_notes)(struct image_params *imgp, Elf_Note *checknote,
      const char *note_vendor, const Elf_Phdr *pnote,
      boolean_t (*cb)(const Elf_Note *, void *, boolean_t *), void *cb_arg)
  {
          const Elf_Note *note, *note0, *note_end;
          const char *note_name;
          char *buf;
          int i, error;
          boolean_t res;
  
          /* We need some limit, might as well use PAGE_SIZE. */
          if (pnote == NULL || pnote->p_filesz > PAGE_SIZE)
                  return (FALSE);
          ASSERT_VOP_LOCKED(imgp->vp, "parse_notes");
          if (pnote->p_offset > PAGE_SIZE ||
              pnote->p_filesz > PAGE_SIZE - pnote->p_offset) {
                  buf = malloc(pnote->p_filesz, M_TEMP, M_NOWAIT);
                  if (buf == NULL) {
                          VOP_UNLOCK(imgp->vp, 0);
                          buf = malloc(pnote->p_filesz, M_TEMP, M_WAITOK);
                          vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
                  }
                  error = vn_rdwr(UIO_READ, imgp->vp, buf, pnote->p_filesz,
                      pnote->p_offset, UIO_SYSSPACE, IO_NODELOCKED,
                      curthread->td_ucred, NOCRED, NULL, curthread);
                  if (error != 0) {
                          uprintf("i/o error PT_NOTE\n");
                          goto retf;
                  }
                  note = note0 = (const Elf_Note *)buf;
                  note_end = (const Elf_Note *)(buf + pnote->p_filesz);
          } else {
                  note = note0 = (const Elf_Note *)(imgp->image_header +
                      pnote->p_offset);
                  note_end = (const Elf_Note *)(imgp->image_header +
                      pnote->p_offset + pnote->p_filesz);
                  buf = NULL;
          }
          for (i = 0; i < 100 && note >= note0 && note < note_end; i++) {
                  if (!aligned(note, Elf32_Addr) || (const char *)note_end -
                      (const char *)note < sizeof(Elf_Note)) {
                          goto retf;
                  }
                  if (note->n_namesz != checknote->n_namesz ||
                      note->n_descsz != checknote->n_descsz ||
                      note->n_type != checknote->n_type)
                          goto nextnote;
                  note_name = (const char *)(note + 1);
                  if (note_name + checknote->n_namesz >=
                      (const char *)note_end || strncmp(note_vendor,
                      note_name, checknote->n_namesz) != 0)
                          goto nextnote;
  
                  if (cb(note, cb_arg, &res))
                          goto ret;
  nextnote:
                  note = (const Elf_Note *)((const char *)(note + 1) +
                      roundup2(note->n_namesz, ELF_NOTE_ROUNDSIZE) +
                      roundup2(note->n_descsz, ELF_NOTE_ROUNDSIZE));
          }
  retf:
          res = FALSE;
  ret:
          free(buf, M_TEMP);
          return (res);
  }
  
  struct brandnote_cb_arg {
          Elf_Brandnote *brandnote;
          int32_t *osrel;
  };
  
  static boolean_t
  brandnote_cb(const Elf_Note *note, void *arg0, boolean_t *res)
  {
          struct brandnote_cb_arg *arg;
  
          arg = arg0;
  
          /*
           * Fetch the osreldate for binary from the ELF OSABI-note if
           * necessary.
           */
          *res = (arg->brandnote->flags & BN_TRANSLATE_OSREL) != 0 &&
              arg->brandnote->trans_osrel != NULL ?
              arg->brandnote->trans_osrel(note, arg->osrel) : TRUE;
  
          return (TRUE);
  }
  
  static Elf_Note fctl_note = {
          .n_namesz = sizeof(FREEBSD_ABI_VENDOR),
          .n_descsz = sizeof(uint32_t),
          .n_type = NT_FREEBSD_FEATURE_CTL,
  };
  
  struct fctl_cb_arg {
          uint32_t *fctl0;
  };
  
  static boolean_t
  note_fctl_cb(const Elf_Note *note, void *arg0, boolean_t *res)
  {
          struct fctl_cb_arg *arg;
          const Elf32_Word *desc;
          uintptr_t p;
  
          arg = arg0;
          p = (uintptr_t)(note + 1);
          p += roundup2(note->n_namesz, ELF_NOTE_ROUNDSIZE);
          desc = (const Elf32_Word *)p;
          *arg->fctl0 = desc[0];
          *res = TRUE;
          return (TRUE);
  }
  
  /*
   * Try to find the appropriate ABI-note section for checknote, fetch
   * the osreldate and feature control flags for binary from the ELF
   * OSABI-note.  Only the first page of the image is searched, the same
   * as for headers.
   */
  static boolean_t
  __elfN(check_note)(struct image_params *imgp, Elf_Brandnote *brandnote,
      int32_t *osrel, uint32_t *fctl0)
  {
          const Elf_Phdr *phdr;
          const Elf_Ehdr *hdr;
          struct brandnote_cb_arg b_arg;
          struct fctl_cb_arg f_arg;
          int i, j;
  
          hdr = (const Elf_Ehdr *)imgp->image_header;
          phdr = (const Elf_Phdr *)(imgp->image_header + hdr->e_phoff);
          b_arg.brandnote = brandnote;
          b_arg.osrel = osrel;
          f_arg.fctl0 = fctl0;
  
          for (i = 0; i < hdr->e_phnum; i++) {
                  if (phdr[i].p_type == PT_NOTE && __elfN(parse_notes)(imgp,
                      &brandnote->hdr, brandnote->vendor, &phdr[i], brandnote_cb,
                      &b_arg)) {
                          for (j = 0; j < hdr->e_phnum; j++) {
                                  if (phdr[j].p_type == PT_NOTE &&
                                      __elfN(parse_notes)(imgp, &fctl_note,
                                      FREEBSD_ABI_VENDOR, &phdr[j],
                                      note_fctl_cb, &f_arg))
                                          break;
                          }
                          return (TRUE);
                  }
          }
          return (FALSE);
  
  }
  
  /*
   * Tell kern_execve.c about it, with a little help from the linker.
   */
  static struct execsw __elfN(execsw) = {
          .ex_imgact = __CONCAT(exec_, __elfN(imgact)),
          .ex_name = __XSTRING(__CONCAT(ELF, __ELF_WORD_SIZE))
  };
  EXEC_SET(__CONCAT(elf, __ELF_WORD_SIZE), __elfN(execsw));
  
  static vm_prot_t
  __elfN(trans_prot)(Elf_Word flags)
  {
          vm_prot_t prot;
  
          prot = 0;
          if (flags & PF_X)
                  prot |= VM_PROT_EXECUTE;
          if (flags & PF_W)
                  prot |= VM_PROT_WRITE;
          if (flags & PF_R)
                  prot |= VM_PROT_READ;
  #if __ELF_WORD_SIZE == 32
  #if defined(__amd64__)
          if (i386_read_exec && (flags & PF_R))
                  prot |= VM_PROT_EXECUTE;
  #endif
  #endif
          return (prot);
  }
  
  static Elf_Word
  __elfN(untrans_prot)(vm_prot_t prot)
  {
          Elf_Word flags;
  
          flags = 0;
          if (prot & VM_PROT_EXECUTE)
                  flags |= PF_X;
          if (prot & VM_PROT_READ)
                  flags |= PF_R;
          if (prot & VM_PROT_WRITE)
                  flags |= PF_W;
          return (flags);
  }
  
  void
  __elfN(stackgap)(struct image_params *imgp, u_long *stack_base)
  {
          u_long range, rbase, gap;
          int pct;
  
          pct = __elfN(aslr_stack_gap);
          if (pct == 0)
                  return;
          if (pct > 50)
                  pct = 50;
          range = imgp->eff_stack_sz * pct / 100;
          arc4rand(&rbase, sizeof(rbase), 0);
          gap = rbase % range;
          gap &= ~(sizeof(u_long) - 1);
          *stack_base -= gap;
  }

Cache object: 5c7cd53f5490bd49d00f099efb5b1d9b