The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*      $NetBSD: exec_aout.c,v 1.41 2019/11/20 19:37:53 pgoyette Exp $  */
    2 
    3 /*
    4  * Copyright (c) 1993, 1994 Christopher G. Demetriou
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  * 3. All advertising materials mentioning features or use of this software
   16  *    must display the following acknowledgement:
   17  *      This product includes software developed by Christopher G. Demetriou.
   18  * 4. The name of the author may not be used to endorse or promote products
   19  *    derived from this software without specific prior written permission
   20  *
   21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   24  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   26  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   30  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   31  */
   32 
   33 #include <sys/cdefs.h>
   34 __KERNEL_RCSID(0, "$NetBSD: exec_aout.c,v 1.41 2019/11/20 19:37:53 pgoyette Exp $");
   35 
   36 #include <sys/param.h>
   37 #include <sys/systm.h>
   38 #include <sys/proc.h>
   39 #include <sys/vnode.h>
   40 #include <sys/exec.h>
   41 #include <sys/exec_aout.h>
   42 #include <sys/resourcevar.h>
   43 #include <sys/module.h>
   44 
   45 #include <uvm/uvm_extern.h>
   46 
   47 MODULE(MODULE_CLASS_EXEC, exec_aout, NULL);
   48 
   49 static struct execsw exec_aout_execsw = {
   50         .es_hdrsz = sizeof(struct exec),
   51         .es_makecmds = exec_aout_makecmds,
   52         .u = {
   53                 .elf_probe_func = NULL,
   54         },
   55         .es_emul = &emul_netbsd,
   56         .es_prio = EXECSW_PRIO_ANY,
   57         .es_arglen = 0,
   58         .es_copyargs = copyargs,
   59         .es_setregs = NULL,
   60         .es_coredump = coredump_netbsd,
   61         .es_setup_stack = exec_setup_stack,
   62 };
   63 
   64 static int
   65 exec_aout_modcmd(modcmd_t cmd, void *arg)
   66 {
   67 
   68         switch (cmd) {
   69         case MODULE_CMD_INIT:
   70                 return exec_add(&exec_aout_execsw, 1);
   71 
   72         case MODULE_CMD_FINI:
   73                 return exec_remove(&exec_aout_execsw, 1);
   74 
   75         default:
   76                 return ENOTTY;
   77         }
   78 }
   79 
   80 /*
   81  * exec_aout_makecmds(): Check if it's an a.out-format executable.
   82  *
   83  * Given a lwp pointer and an exec package pointer, see if the referent
   84  * of the epp is in a.out format.  First check 'standard' magic numbers for
   85  * this architecture.  If that fails, try a CPU-dependent hook.
   86  *
   87  * This function, in the former case, or the hook, in the latter, is
   88  * responsible for creating a set of vmcmds which can be used to build
   89  * the process's vm space and inserting them into the exec package.
   90  */
   91 
   92 int
   93 exec_aout_makecmds(struct lwp *l, struct exec_package *epp)
   94 {
   95         u_long midmag, magic;
   96         u_short mid;
   97         int error;
   98         struct exec *execp = epp->ep_hdr;
   99 
  100         if (epp->ep_hdrvalid < sizeof(struct exec))
  101                 return ENOEXEC;
  102 
  103         midmag = ntohl(execp->a_midmag);
  104         mid = (midmag >> 16) & 0x3ff;
  105         magic = midmag & 0xffff;
  106 
  107         midmag = mid << 16 | magic;
  108 
  109         switch (midmag) {
  110         case (MID_MACHINE << 16) | ZMAGIC:
  111                 error = exec_aout_prep_zmagic(l, epp);
  112                 break;
  113         case (MID_MACHINE << 16) | NMAGIC:
  114                 error = exec_aout_prep_nmagic(l, epp);
  115                 break;
  116         case (MID_MACHINE << 16) | OMAGIC:
  117                 error = exec_aout_prep_omagic(l, epp);
  118                 break;
  119         default:
  120                 error = cpu_exec_aout_makecmds(l, epp);
  121         }
  122 
  123         if (error)
  124                 kill_vmcmds(&epp->ep_vmcmds);
  125         else
  126                 epp->ep_flags &= ~EXEC_TOPDOWN_VM;
  127 
  128         return error;
  129 }
  130 
  131 /*
  132  * exec_aout_prep_zmagic(): Prepare a 'native' ZMAGIC binary's exec package
  133  *
  134  * First, set of the various offsets/lengths in the exec package.
  135  *
  136  * Then, mark the text image busy (so it can be demand paged) or error
  137  * out if this is not possible.  Finally, set up vmcmds for the
  138  * text, data, bss, and stack segments.
  139  */
  140 
  141 int
  142 exec_aout_prep_zmagic(struct lwp *l, struct exec_package *epp)
  143 {
  144         struct exec *execp = epp->ep_hdr;
  145         int error;
  146 
  147         epp->ep_taddr = AOUT_LDPGSZ;
  148         epp->ep_tsize = execp->a_text;
  149         epp->ep_daddr = epp->ep_taddr + execp->a_text;
  150         epp->ep_dsize = execp->a_data + execp->a_bss;
  151         epp->ep_entry = execp->a_entry;
  152 
  153         error = vn_marktext(epp->ep_vp);
  154         if (error)
  155                 return (error);
  156 
  157         /* set up command for text segment */
  158         NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_pagedvn, round_page(execp->a_text),
  159             epp->ep_taddr, epp->ep_vp, 0, VM_PROT_READ|VM_PROT_EXECUTE);
  160 
  161         /* set up command for data segment */
  162         NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_pagedvn, round_page(execp->a_data),
  163             epp->ep_daddr, epp->ep_vp, execp->a_text,
  164             VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);
  165 
  166         /* set up command for bss segment */
  167         if (execp->a_bss > 0)
  168                 NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_zero, execp->a_bss,
  169                     epp->ep_daddr + execp->a_data, NULLVP, 0,
  170                     VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);
  171 
  172         return (*epp->ep_esch->es_setup_stack)(l, epp);
  173 }
  174 
  175 /*
  176  * exec_aout_prep_nmagic(): Prepare a 'native' NMAGIC binary's exec package
  177  */
  178 
  179 int
  180 exec_aout_prep_nmagic(struct lwp *l, struct exec_package *epp)
  181 {
  182         struct exec *execp = epp->ep_hdr;
  183         long bsize, baddr;
  184 
  185         epp->ep_taddr = AOUT_LDPGSZ;
  186         epp->ep_tsize = execp->a_text;
  187         epp->ep_daddr = roundup(epp->ep_taddr + execp->a_text, AOUT_LDPGSZ);
  188         epp->ep_dsize = execp->a_data + execp->a_bss;
  189         epp->ep_entry = execp->a_entry;
  190 
  191         /* set up command for text segment */
  192         NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, execp->a_text,
  193             epp->ep_taddr, epp->ep_vp, sizeof(struct exec),
  194             VM_PROT_READ|VM_PROT_EXECUTE);
  195 
  196         /* set up command for data segment */
  197         NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, execp->a_data,
  198             epp->ep_daddr, epp->ep_vp, execp->a_text + sizeof(struct exec),
  199             VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);
  200 
  201         /* set up command for bss segment */
  202         baddr = round_page(epp->ep_daddr + execp->a_data);
  203         bsize = epp->ep_daddr + epp->ep_dsize - baddr;
  204         if (bsize > 0)
  205                 NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_zero, bsize, baddr,
  206                     NULLVP, 0, VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);
  207 
  208         return (*epp->ep_esch->es_setup_stack)(l, epp);
  209 }
  210 
  211 /*
  212  * exec_aout_prep_omagic(): Prepare a 'native' OMAGIC binary's exec package
  213  */
  214 
  215 int
  216 exec_aout_prep_omagic(struct lwp *l, struct exec_package *epp)
  217 {
  218         struct exec *execp = epp->ep_hdr;
  219         long dsize, bsize, baddr;
  220 
  221         epp->ep_taddr = AOUT_LDPGSZ;
  222         epp->ep_tsize = execp->a_text;
  223         epp->ep_daddr = epp->ep_taddr + execp->a_text;
  224         epp->ep_dsize = execp->a_data + execp->a_bss;
  225         epp->ep_entry = execp->a_entry;
  226 
  227         /* set up command for text and data segments */
  228         NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn,
  229             execp->a_text + execp->a_data, epp->ep_taddr, epp->ep_vp,
  230             sizeof(struct exec), VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);
  231 
  232         /* set up command for bss segment */
  233         baddr = round_page(epp->ep_daddr + execp->a_data);
  234         bsize = epp->ep_daddr + epp->ep_dsize - baddr;
  235         if (bsize > 0)
  236                 NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_zero, bsize, baddr,
  237                     NULLVP, 0, VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);
  238 
  239         /*
  240          * Make sure (# of pages) mapped above equals (vm_tsize + vm_dsize);
  241          * obreak(2) relies on this fact. Both `vm_tsize' and `vm_dsize' are
  242          * computed (in execve(2)) by rounding *up* `ep_tsize' and `ep_dsize'
  243          * respectively to page boundaries.
  244          * Compensate `ep_dsize' for the amount of data covered by the last
  245          * text page.
  246          */
  247         dsize = epp->ep_dsize + execp->a_text - round_page(execp->a_text);
  248         epp->ep_dsize = (dsize > 0) ? dsize : 0;
  249         return (*epp->ep_esch->es_setup_stack)(l, epp);
  250 }

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