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/*
* This file is part of the libpayload project.
*
* Copyright (C) 2008 Advanced Micro Devices, Inc.
*
* 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. 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 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.
*/
.global _entry, _leave
.text
.align 4
/*
* Our entry point - assume that the CPU is in 32 bit protected mode and
* all segments are in a flat model. That's our operating mode, so we won't
* change anything.
*/
_entry:
call _init
/* We're back - go back to the bootloader. */
ret
/*
* This function saves off the previous stack and switches us to our
* own execution environment.
*/
_init:
/* No interrupts, please. */
cli
/* Store current stack pointer. */
movl %esp, %esi
/* Setup new stack. */
movl _istack, %ebx
movl (%ebx), %esp
/* Save old stack pointer. */
pushl %esi
/* Let's rock. */
call start_main
_leave:
/* Get old stack pointer. */
popl %ebx
/* Restore old stack. */
movl %esp, %ebx
/* Return to the original context. */
lret
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