xref: /freebsd-11-stable/stand/userboot/userboot/elf32_freebsd.c

/*-
 * Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: stable/11/stand/userboot/userboot/elf32_freebsd.c 261504 2014-02-05 04:39:03Z jhb $");

#include <sys/param.h>
#include <sys/exec.h>
#include <sys/linker.h>
#include <string.h>
#define	_MACHINE_ELF_WANT_32BIT
#include <i386/include/bootinfo.h>
#include <i386/include/elf.h>
#include <stand.h>

#include "bootstrap.h"
#include "libuserboot.h"

static int	elf32_exec(struct preloaded_file *amp);
static int	elf32_obj_exec(struct preloaded_file *amp);

struct file_format i386_elf = { elf32_loadfile, elf32_exec };
struct file_format i386_elf_obj = { elf32_obj_loadfile, elf32_obj_exec };

#define	GUEST_STACK	0x1000		/* Initial stack base */
#define	GUEST_GDT	0x3000		/* Address of initial GDT */

/*
 * There is an ELF kernel and one or more ELF modules loaded.
 * We wish to start executing the kernel image, so make such
 * preparations as are required, and do so.
 */
static int
elf32_exec(struct preloaded_file *fp)
{
	struct file_metadata	*md;
	Elf_Ehdr 		*ehdr;
	vm_offset_t		entry, bootinfop, modulep, kernend;
	int			boothowto, err, bootdev;
	uint32_t		stack[1024], *sp;


	if ((md = file_findmetadata(fp, MODINFOMD_ELFHDR)) == NULL)
		return(EFTYPE);
	ehdr = (Elf_Ehdr *)&(md->md_data);

	err = bi_load32(fp->f_args, &boothowto, &bootdev, &bootinfop, &modulep, &kernend);
	if (err != 0)
		return(err);
	entry = ehdr->e_entry & 0xffffff;

#ifdef DEBUG
	printf("Start @ 0x%lx ...\n", entry);
#endif

	dev_cleanup();

	/*
	 * Build a scratch stack at physical 0x1000
	 */
	memset(stack, 0, sizeof(stack));
	sp = (uint32_t *)((char *)stack + sizeof(stack));
	*--sp = kernend;
	*--sp = modulep;
	*--sp = bootinfop;
	*--sp = 0;
	*--sp = 0;
	*--sp = 0;
	*--sp = bootdev;
	*--sp = boothowto;

	/*
	 * Fake return address to mimic "new" boot blocks.  For more
	 * details see recover_bootinfo in locore.S.
	 */
	*--sp = 0xbeefface;
	CALLBACK(copyin, stack, GUEST_STACK, sizeof(stack));
	CALLBACK(setreg, 4, (char *)sp - (char *)stack + GUEST_STACK);

	CALLBACK(setgdt, GUEST_GDT, 8 * 4 - 1);

        CALLBACK(exec, entry);

	panic("exec returned");
}

static int
elf32_obj_exec(struct preloaded_file *fp)
{
	return (EFTYPE);
}