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/*
* Ported to boot 386BSD by Julian Elischer (julian@tfs.com) Sept 1992
*
* Mach Operating System
* Copyright (c) 1992, 1991 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie Mellon
* the rights to redistribute these changes.
*/
/*
* HISTORY
* $Log: asm.s,v $
* Revision 2.2 92/04/04 11:34:13 rpd
* Fix Intel Copyright as per B. Davies authorization.
* [92/04/03 rvb]
* From 2.5 boot: pruned inb(), outb(), and pzero().
* [92/03/30 rvb]
*
* Revision 2.2 91/04/02 14:35:10 mbj
* Added _sp() => where is the stack at. [kupfer]
* Add Intel copyright
* [90/02/09 rvb]
*
*/
/*
Copyright 1988, 1989, 1990, 1991, 1992
by Intel Corporation, Santa Clara, California.
All Rights Reserved
Permission to use, copy, modify, and distribute this software and
its documentation for any purpose and without fee is hereby
granted, provided that the above copyright notice appears in all
copies and that both the copyright notice and this permission notice
appear in supporting documentation, and that the name of Intel
not be used in advertising or publicity pertaining to distribution
of the software without specific, written prior permission.
INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS,
IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
.file "asm.s"
#include "asm.h"
CR0_PE_ON = 0x1
CR0_PE_OFF = 0xfffffffe
.globl _ouraddr
.text
/*
#
# real_to_prot()
# transfer from real mode to protected mode.
*/
ENTRY(real_to_prot)
# guarantee that interrupt is disabled when in prot mode
cli
# load the gdtr
addr16
data32
lgdt EXT(Gdtr)
# set the PE bit of CR0
mov %cr0, %eax
data32
or $CR0_PE_ON, %eax
mov %eax, %cr0
# make intrasegment jump to flush the processor pipeline and
# reload CS register
data32
ljmp $0x18, $xprot
xprot:
# we are in USE32 mode now
# set up the protective mode segment registers : DS, SS, ES
mov $0x20, %eax
movw %ax, %ds
movw %ax, %ss
movw %ax, %es
ret
/*
#
# prot_to_real()
# transfer from protected mode to real mode
#
*/
ENTRY(prot_to_real)
# set up a dummy stack frame for the second seg change.
movl _ouraddr, %eax
sarl $4, %eax
pushw %ax
pushw $xreal
# Change to use16 mode.
ljmp $0x28, $x16
x16:
# clear the PE bit of CR0
mov %cr0, %eax
data32
and $CR0_PE_OFF, %eax
mov %eax, %cr0
# make intersegment jmp to flush the processor pipeline
# using the fake stack frame set up earlier
# and reload CS register
lret
xreal:
# we are in real mode now
# set up the real mode segment registers : DS, SS, ES
movw %cs, %ax
movw %ax, %ds
movw %ax, %ss
movw %ax, %es
data32
ret
/*
#
# startprog(phyaddr)
# start the program on protected mode where phyaddr is the entry point
#
*/
ENTRY(startprog)
push %ebp
mov %esp, %ebp
# get things we need into registers
movl 0x8(%ebp), %ecx # entry offset
movl 0x0c(%ebp), %eax # &argv
# make a new stack at 0:0xa0000 (big segs)
mov $0x10, %ebx
movw %bx, %ss
movl $0xa0000,%ebx
movl %ebx,%esp
# push some number of args onto the stack
pushl $0 # nominally a cyl offset in the boot.
pushl 0x8(%eax) # argv[2] = bootdev
pushl 0x4(%eax) # argv[1] = howto
pushl $0 # dummy 'return' address
# push on our entry address
mov $0x08, %ebx # segment
pushl %ebx
pushl %ecx
# convert over the other data segs
mov $0x10, %ebx
movw %bx, %ds
movw %bx, %es
# convert the PC (and code seg)
lret
/*
#
# pbzero( dst, cnt)
# where src is a virtual address and dst is a physical address
*/
ENTRY(pbzero)
push %ebp
mov %esp, %ebp
push %es
push %esi
push %edi
push %ecx
cld
# set %es to point at the flat segment
mov $0x10, %eax
movw %ax, %es
mov 0x8(%ebp), %edi # destination
mov 0xc(%ebp), %ecx # count
mov $0x0,%eax # value
rep
stosb
pop %ecx
pop %edi
pop %esi
pop %es
pop %ebp
ret
/*
#
# pcpy(src, dst, cnt)
# where src is a virtual address and dst is a physical address
#
*/
ENTRY(pcpy)
push %ebp
mov %esp, %ebp
push %es
push %esi
push %edi
push %ecx
cld
# set %es to point at the flat segment
mov $0x10, %eax
movw %ax, %es
mov 0x8(%ebp), %esi # source
mov 0xc(%ebp), %edi # destination
mov 0x10(%ebp), %ecx # count
rep
movsb
pop %ecx
pop %edi
pop %esi
pop %es
pop %ebp
ret
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