diff options
Diffstat (limited to 'sys/i386/apm/apm_init/real_prot.S')
| -rw-r--r-- | sys/i386/apm/apm_init/real_prot.S | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/sys/i386/apm/apm_init/real_prot.S b/sys/i386/apm/apm_init/real_prot.S new file mode 100644 index 0000000..d61a394 --- /dev/null +++ b/sys/i386/apm/apm_init/real_prot.S @@ -0,0 +1,185 @@ +/* + * 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 + * $Id: asm.S,v 1.2 1993/10/16 19:11:27 rgrimes Exp $ + */ + + +/* + 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. +*/ + +/* + * LP (Laptop Package) + * + * Copyright (C) 1994 by HOSOKAWA, Tatsumi <hosokawa@mt.cs.keio.ac.jp> + * + * This software may be used, modified, copied, and distributed, in + * both source and binary form provided that the above copyright and + * these terms are retained. Under no circumstances is the author + * responsible for the proper functioning of this software, nor does + * the author assume any responsibility for damages incurred with its + * use. + * + * Sep., 1994 Implemented on FreeBSD 1.1.5.1R (Toshiba AVS001WD) + */ + +/* + * Modified for APM BIOS initializer by HOSOKAWA Tatsumi + * + * See also locore.s. It supports these functions works correctly. + */ + + .file "real_prot.S" + +#include "real_prot.h" +#include "apm_segments.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 + + /* + * deleted for APM initializer by HOSOKAWA Tatsumi + * <hosoakwa@mt.cs.keio.ac.jp> + */ +#if 0 + /* load the gdtr */ + addr32 + data32 + lgdt EXT(Gdtr) +#endif + + /* 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 $(APM_INIT_CS_SEL), $xprot + +xprot: + /* + * we are in USE32 mode now + * set up the protected mode segment registers : DS, SS, ES + */ + mov $(APM_INIT_DS_SEL), %eax + movw %ax, %ds + movw %ax, %ss + movw %ax, %es + + /* load idtr so we can debug */ + lidt EXT(Idtr_prot) + + 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 + movw $xreal, %ax /* gas botches pushw $xreal - extra bytes 0, 0*/ + pushw %ax /* decode to add %al, (%eax) (%al usually 0) */ + + /* Change to use16 mode. */ + ljmp $(APM_INIT_CS16_SEL), $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 + + /* load idtr so we can debug */ + addr32 + data32 + lidt EXT(Idtr_real) + + data32 + ret |
