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/*
* This file is part of the libpayload project.
*
* Copyright (C) 2008 Advanced Micro Devices, Inc.
* Copyright (C) 2017 Patrick Rudolph <siro@das-labor.org>
*
* 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.
*/
.code32
.global _entry
.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:
jmp _init
.align 4
#define MB_MAGIC 0x1BADB002
#define MB_FLAGS 0x00010003
mb_header:
.long MB_MAGIC
.long MB_FLAGS
.long -(MB_MAGIC + MB_FLAGS)
.long mb_header
.long _start
.long _edata
.long _end
.long _init
#define CB_MAGIC_VALUE 0x12345678
#define CB_MAGIC 0x04
#define CB_ARGV 0x08
#define CB_ARGC 0x10
/*
* This function saves off the previous stack and switches us to our
* own execution environment.
*/
_init:
/* No interrupts, please. */
cli
/* Store EAX and EBX */
movl %eax, loader_eax
movl %ebx, loader_ebx
/* Copy argv[] and argc as demanded by the Payload API,
* see https://www.coreboot.org/Payload_API and exec.S.
*/
cmpl $CB_MAGIC_VALUE, CB_MAGIC(%esp)
jne 1f
movl CB_ARGV(%esp), %eax
movl %eax, main_argv
movl CB_ARGC(%esp), %eax
movl %eax, main_argc
1:
/* Store current stack pointer and set up new stack. */
movl %esp, %eax
movl $_stack, %esp
pushl %eax
/* Enable special x86 functions if present. */
pushl %eax
pushl %ebx
pushl %ecx
pushl %edx
movl $0, %eax
cpuid
/* Test if CPUID(eax=1) is available. */
test %eax, %eax
je cpuid_done
/* Get CPU features. */
movl $1, %eax
cpuid
cpuid_fpu:
/* Test if x87 FPU is present */
test $1, %edx
je cpuid_sse
fninit
movl %cr0, %eax
andl $0xFFFFFFFB, %eax /* clear EM */
orl $0x00000022, %eax /* set MP, NE */
movl %eax, %cr0
cpuid_sse:
/* Test if SSE is available */
test $0x02000000, %edx
je cpuid_done
movl %cr4, %eax
orl $0x00000600, %eax /* set OSFXSR, OSXMMEXCPT */
movl %eax, %cr4
cpuid_done:
popl %edx
popl %ecx
popl %ebx
popl %eax
/* Let's rock. */
call start_main
/* %eax has the return value - pass it on unmolested */
_leave:
/* Restore old stack. */
popl %esp
/* Return to the original context. */
ret
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