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/* $NetBSD: asm.S,v 1.12 1995/03/12 00:10:53 mycroft Exp $ */
/*
* 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.
*/
/*
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.
*/
#include <machine/asm.h>
#define addr32 .byte 0x67
#define data32 .byte 0x66
CR0_PE = 0x1
.data
.globl _ourseg
_ourseg:
.long 0
/*
* 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 _C_LABEL(Gdtr)
# set the PE bit of CR0
movl %cr0, %eax
data32
orl $CR0_PE, %eax
movl %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
movl $0x20, %eax
movl %ax, %ds
movl %ax, %ss
movl %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 _ourseg, %eax
pushw %ax
movl $xreal, %eax # gas botches pushw $xreal - extra bytes 0, 0
pushw %ax # decode to add %al, (%eax) (%al usually 0)
# Change to use16 mode.
ljmp $0x28, $x16
x16:
# clear the PE bit of CR0
movl %cr0, %eax
data32
andl $~CR0_PE, %eax
movl %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
movl %cs, %ax
movl %ax, %ds
movl %ax, %ss
movl %ax, %es
sti
data32
ret
/*
* startprog(phyaddr)
* start the program on protected mode where phyaddr is the entry point
*/
ENTRY(startprog)
pushl %ebp
movl %esp, %ebp
# get things we need into registers
movl 8(%ebp), %ecx # entry offset
movl 12(%ebp), %eax # &argv
# make a new stack at 0:0x90000 (big segs)
movl $0x10, %ebx
movw %bx, %ss
movl $0x90000, %ebx
movl %ebx, %esp
# push some number of args onto the stack
pushl 28(%eax) # argv[7] = cnvmem
pushl 32(%eax) # argv[8] = extmem
pushl 16(%eax) # argv[4] = esym
pushl $0 # nominally a cyl offset in the boot.
pushl 8(%eax) # argv[2] = bootdev
pushl 4(%eax) # argv[1] = howto
pushl $0 # dummy 'return' address
# push on our entry address
movl $0x8, %ebx # segment
pushl %ebx
pushl %ecx
# convert over the other data segs
movl $0x10, %ebx
movl %bx, %ds
movl %bx, %es
# convert the PC (and code seg)
lret
/*
* pbzero(dst, cnt)
* where dst is a virtual address and cnt is the length
*/
ENTRY(pbzero)
pushl %ebp
movl %esp, %ebp
pushl %es
pushl %edi
cld
# set %es to point at the flat segment
movl $0x10, %eax
movl %ax, %es
movl 8(%ebp), %edi # destination
movl 12(%ebp), %ecx # count
xorl %eax, %eax # value
rep
stosb
popl %edi
popl %es
popl %ebp
ret
/*
* pcpy(src, dst, cnt)
* where src is a virtual address and dst is a physical address
*/
ENTRY(pcpy)
pushl %ebp
movl %esp, %ebp
pushl %es
pushl %esi
pushl %edi
cld
# set %es to point at the flat segment
movl $0x10, %eax
movl %ax, %es
movl 8(%ebp), %esi # source
movl 12(%ebp), %edi # destination
movl 16(%ebp), %ecx # count
rep
movsb
popl %edi
popl %esi
popl %es
popl %ebp
ret
#ifdef CHECKSUM
/*
* cksum(src, cnt)
* where src is a virtual address and cnt is the length
*/
ENTRY(cksum)
pushl %ebp
movl %esp, %ebp
pushl %es
pushl %edi
cld
# set %es to point at the flat segment
movl $0x10, %eax
movl %ax, %es
movl 8(%ebp), %edi # destination
movl 12(%ebp), %ecx # count
shrl $2, %ecx
xorl %edx, %edx # value
1: es
lodsl
xorl %eax, %edx
loop 1b
movl %edx, %eax
popl %edi
popl %es
popl %ebp
ret
#endif
#if 0
ENTRY(getword)
pushl %ebp
movl %esp, %ebp
pushl %es
# set %es to point at the flat segment
movl $0x10, %eax
movl %ax, %es
movl 8(%ebp), %eax
es
movl (%eax), %edx
movl %edx, %eax
popl %es
popl %ebp
ret
#endif
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