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/*
* 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.
*
* from: Mach, Revision 2.2 92/04/04 11:34:13 rpd
* $FreeBSD$
*/
/*
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
.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 */
addr32
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 protected mode segment registers : DS, SS, ES, FS
*/
movw $0x20, %ax /* data segment */
mov %ax, %ds /* gas would waste a prefix byte for movw */
mov %ax, %ss
mov %ax, %es
movw $0x10, %ax /* flat segment */
mov %ax, %fs
#ifdef BDE_DEBUGGER
/* load idtr so we can debug */
lidt EXT(Idtr_prot)
#endif
ret
/*
*
* prot_to_real()
* transfer from protected mode to real mode
*
*/
ENTRY(prot_to_real)
/* Prepare %ax while we're still in a mode that gas understands. */
movw $0x30, %ax
/* Change to use16 mode. */
ljmp $0x28, $x16
x16:
mov %ax, %ds
mov %ax, %ss
mov %ax, %es
mov %ax, %fs
/* 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
* and reload CS register
*/
data32
ljmp $BOOTSEG, $xreal
xreal:
/*
* we are in real mode now
* set up the real mode segment registers : DS, SS, ES, FS
*/
mov %cs, %ax
mov %ax, %ds
mov %ax, %ss
mov %ax, %es
mov %ax, %fs
#ifdef BDE_DEBUGGER
/* load idtr so we can debug */
addr32
data32
lidt EXT(Idtr_real)
#endif
data32
ret
/*
* startprog(phyaddr)
* start the program on protected mode where phyaddr is the entry point
*
* XXX This whole mess should go away and we should run the boot code in
* flat 32 bit mode with it linked -T BOOTSEG. See the netboot code for
* how this is done.
*/
ENTRY(startprog)
push %ebp
mov %esp, %ebp
movl %esp, %eax /* Use eax as the old stack pointer */
/* convert the current stack to a 32 bit flat model */
movw $0x10, %bx
mov %bx, %ss
addl $(BOOTSEG<<4),%esp
/* copy the arguments from the old stack to the new stack */
pushl 0x14(%eax) /* &bootinfo */
pushl $0 /* was &nfsdiskless */
pushl $0 /* was esym */
pushl $0 /* was cyloffset */
pushl 0x10(%eax) /* bootdev */
pushl 0x0C(%eax) /* howto */
movl $(ourreturn),%ebx
addl $(BOOTSEG<<4),%ebx /* Fix it up for flat segments */
pushl %ebx /* our return address */
/* push on our entry address */
pushl $0x08 /* segment selector */
pushl 0x08(%eax) /* kernel entry address */
/* convert over the other data segs */
movw $0x10, %bx
mov %bx, %ds
mov %bx, %es
/* convert the PC (and code seg) */
lret
ourreturn:
/* For now there is not much we can do, just lock in a loop */
jmp ourreturn
/*
* 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 */
movw $0x10, %ax
mov %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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