xref: /freebsd/stand/i386/libi386/multiboot_tramp.S (revision b3e7694832e81d7a904a10f525f8797b753bf0d3)
1/*-
2 * Copyright (c) 2014  Roger Pau Monné <royger@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#define ASM_FILE
28#include "multiboot.h"
29
30/*
31 * The multiboot specification requires the executable to be launched
32 * with %cs set to a flat read/execute segment with offset 0 and limit
33 * 0xFFFFFFFF, and the rest of the segment registers (%ds, %es, %fs,
34 * %gs, %ss) to flat read/write segments with the same offset and limit.
35 * This is already done by the BTX code before calling multiboot_tramp,
36 * so there is no need to do anything here.
37 */
38
39	.globl	multiboot_tramp
40multiboot_tramp:
41	/* Be sure that interrupts are disabled. */
42	cli
43
44	movl    $MULTIBOOT_BOOTLOADER_MAGIC, %eax
45	/* Get the entry point and address of the multiboot_info parameter. */
46	movl	8(%esp), %ebx
47	movl	4(%esp), %ecx
48
49	call    *%ecx
50