2 * This file is part of the libpayload project.
4 * Copyright (C) 2008 Advanced Micro Devices, Inc.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 .global _entry, _leave
36 * Our entry point - assume that the CPU is in 32 bit protected mode and
37 * all segments are in a flat model. That's our operating mode, so we won't
43 /* We're back - go back to the bootloader. */
48 #define MB_MAGIC 0x1BADB002
49 #define MB_FLAGS 0x00010003
54 .long -(MB_MAGIC + MB_FLAGS)
62 * This function saves off the previous stack and switches us to our
63 * own execution environment.
66 /* No interrupts, please. */
69 /* Store current stack pointer. */
72 /* Store EAX and EBX */
84 /* Setup new stack. */
89 /* Save old stack pointer. */
95 /* %eax has the return value - pass it on unmolested */
97 /* Get old stack pointer. */
100 /* Restore old stack. */
103 /* Return to the original context. */