freebsd-dev/sys/i386/boot/asm.S
Rodney W. Grimes 12fafb2d5a 1. Completely rewritten Makefile that uses bsd.prog.mk more effectively.
2.  Clean up the .S files to use /* */ style comments.

This is a totally cosmetic change, not one byte of the resulting boot
code changes.  But at least it is installed with correct owners and in
the right places, and gets recompiled correctly when things change!
1994-10-02 05:18:26 +00:00

269 lines
5.4 KiB
ArmAsm

/*
* 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 1.3 1994/08/30 01:38:02 bde 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.
*/
.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 */
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
*/
mov $0x20, %eax
movw %ax, %ds
movw %ax, %ss
movw %ax, %es
#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)
/* 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 $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
#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
*/
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 /* was 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