/*      $NetBSD: vax1k_exec.c,v 1.20 2024/09/08 09:36:50 rillig Exp $   */

/*
* Copyright (c) 1993, 1994 Christopher G. Demetriou
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
*    must display the following acknowledgement:
*      This product includes software developed by Christopher G. Demetriou.
* 4. 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.
*/

/*
* Exec glue to provide compatibility with older NetBSD vax1k exectuables.
*
* Because NetBSD/vax now uses 4k page size, older binaries (that started
* on an 1k boundary) cannot be mmap'ed. Therefore they are read in
* (via vn_rdwr) as OMAGIC binaries and executed. This will use a little
* bit more memory, but otherwise won't affect the execution speed.
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vax1k_exec.c,v 1.20 2024/09/08 09:36:50 rillig Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/vnode.h>
#include <sys/exec.h>
#include <sys/resourcevar.h>
#include <sys/module.h>

#include <compat/vax1k/vax1k_exec.h>

#if defined(_KERNEL_OPT)
#include "opt_compat_43.h"
#else
#define COMPAT_43       /* enable 4.3BSD binaries for lkm */
#endif

MODULE(MODULE_CLASS_EXEC, exec_vax1k, NULL);

int     exec_vax1k_prep_anymagic(struct lwp *, struct exec_package *,
           size_t, bool);

static struct execsw exec_vax1k_execsw = {
       /* NetBSD vax1k a.out */
       .es_hdrsz = sizeof(struct exec),
       .es_makecmds = exec_vax1k_makecmds,
       .u = {
               .elf_probe_func = NULL,
       },
       .es_emul = &emul_netbsd,
       .es_prio = EXECSW_PRIO_ANY,
       .es_arglen = 0,
       .es_copyargs = copyargs,
       .es_setregs = NULL,
       .es_coredump = coredump_netbsd,
       .es_setup_stack = exec_setup_stack,
};

static int
exec_vax1k_modcmd(modcmd_t cmd, void *arg)
{

       switch (cmd) {
       case MODULE_CMD_INIT:
               return exec_add(&exec_vax1k_execsw, 1);

       case MODULE_CMD_FINI:
               return exec_remove(&exec_vax1k_execsw, 1);

       default:
               return ENOTTY;
       }
}

/*
* exec_vax1k_makecmds(): Check if it's an a.out-format executable
* with a vax1k magic number.
*
* Given a proc pointer and an exec package pointer, see if the referent
* of the epp is in a.out format.  Just check 'standard' magic numbers for
* this architecture.
*
* This function, in the former case, or the hook, in the latter, is
* responsible for creating a set of vmcmds which can be used to build
* the process's vm space and inserting them into the exec package.
*/

int
exec_vax1k_makecmds(struct lwp *l, struct exec_package *epp)
{
       u_long midmag, magic;
       u_short mid;
       int error;
       struct exec *execp = epp->ep_hdr;

       if (epp->ep_hdrvalid < sizeof(struct exec))
               return ENOEXEC;

       midmag = ntohl(execp->a_midmag);
       mid = (midmag >> 16) & 0x3ff;
       magic = midmag & 0xffff;

       midmag = mid << 16 | magic;

       switch (midmag) {
       case (MID_VAX1K << 16) | ZMAGIC:
               error = exec_vax1k_prep_anymagic(l, epp, 0, false);
               goto done;

       case (MID_VAX1K << 16) | NMAGIC:
               error = exec_vax1k_prep_anymagic(l, epp,
                                                sizeof(struct exec), true);
               goto done;

       case (MID_VAX1K << 16) | OMAGIC:
               error = exec_vax1k_prep_anymagic(l, epp,
                                                sizeof(struct exec), false);
               goto done;
       }

#ifdef COMPAT_43
       /*
        * 4.3BSD pre-dates CPU midmag (e.g. MID_VAX1K).   instead, we
        * expect a magic number in native byte order.
        */
       switch (execp->a_midmag) {
       case ZMAGIC:
               error = exec_vax1k_prep_anymagic(l, epp, VAX1K_LDPGSZ, false);
               goto done;

       case NMAGIC:
               error = exec_vax1k_prep_anymagic(l, epp,
                                               sizeof(struct exec), true);
               goto done;

       case OMAGIC:
               error = exec_vax1k_prep_anymagic(l, epp,
                                               sizeof(struct exec), false);
               goto done;
       }
#endif

       /* failed... */
       error = ENOEXEC;

done:
       if (error)
               kill_vmcmds(&epp->ep_vmcmds);

       return error;
}

/*
* exec_vax1k_prep_anymagic(): Prepare a vax1k ?MAGIC binary's exec package
*
* First, set of the various offsets/lengths in the exec package.
* Note that all code is mapped RW; no protection, but because it is
* only used for compatibility it won't hurt.
*
*/
int
exec_vax1k_prep_anymagic(struct lwp *l, struct exec_package *epp,
       size_t text_foffset, bool textpad)
{
       struct exec *execp = epp->ep_hdr;

       epp->ep_taddr = execp->a_entry & ~(VAX1K_USRTEXT - 1);
       epp->ep_tsize = execp->a_text;
       epp->ep_daddr = epp->ep_taddr + epp->ep_tsize;
       if (textpad)                    /* pad for NMAGIC? */
               epp->ep_daddr = (epp->ep_daddr + (VAX1K_LDPGSZ - 1)) &
                                               ~(VAX1K_LDPGSZ - 1);
       epp->ep_dsize = execp->a_data;
       epp->ep_entry = execp->a_entry;

       /* first allocate memory for text+data+bss */
       NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_zero,
               round_page(epp->ep_daddr + epp->ep_dsize + execp->a_bss) -
                       trunc_page(epp->ep_taddr),      /* size */
               trunc_page(epp->ep_taddr), NULLVP,      /* addr, vnode */
               0, VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);

       /* then read the text in the area we just allocated */
       NEW_VMCMD(&epp->ep_vmcmds, vmcmd_readvn,
               epp->ep_tsize, epp->ep_taddr, epp->ep_vp, text_foffset,
       VM_PROT_WRITE|VM_PROT_READ|VM_PROT_EXECUTE);

       /* next read the data */
       if (epp->ep_dsize) {
               NEW_VMCMD(&epp->ep_vmcmds, vmcmd_readvn,
                       epp->ep_dsize, epp->ep_daddr, epp->ep_vp,
                       text_foffset + epp->ep_tsize,
                       VM_PROT_WRITE|VM_PROT_READ|VM_PROT_EXECUTE);
       }

       /* now bump up the dsize to include the bss so that sbrk works */
       epp->ep_dsize += execp->a_bss;

       /* finally, setup the stack ... */
       return (*epp->ep_esch->es_setup_stack)(l, epp);
}

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