freebsd-skq/sys/i386/boot/biosboot/boot2.S
rgrimes 93f6cc5abd >From Charles Hannum
Change movl %es: -2(reg) to use a subl $2,reg when fixing up the IDT
entries for bdb.  This seems to be the best way to go.

Some day soon #ifdef BDB all of Bruces debugger code.
1993-11-13 04:43:25 +00:00

170 lines
3.8 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 11:35:26 rpd
* $Id: boot2.S,v 1.2 1993/10/16 19:11:33 rgrimes Exp $
*/
#include "asm.h"
/* Conventional GDT indexes. */
#define BOOT_CS_INDEX 3
#define BOOT_CS16_INDEX 5
#define BOOT_DS_INDEX 4
#define DB_CS_INDEX 14
#define DB_CS16_INDEX 15
#define DB_DS_INDEX 16
#define GDT_INDEX 17
/* Vector numbers. */
#define BREAKPOINT_VECTOR 3
#define DEBUG_VECTOR 1
/*
* boot2() -- second stage boot
*/
.globl EXT(ouraddr)
ENTRY(boot2)
data32
subl %eax, %eax
mov %cs, %ax
mov %ax, %ds
mov %ax, %es
data32
shll $4, %eax
addr32
data32
movl %eax, EXT(ouraddr)
/* fix up GDT entries for bootstrap */
#define FIXUP(gdt_index) \
addr32; \
movl %eax, EXT(Gdt)+(8*gdt_index)+2; /* actually movw %ax */ \
addr32; \
movb %bl, EXT(Gdt)+(8*gdt_index)+4
data32
shld $16, %eax, %ebx
FIXUP(BOOT_CS_INDEX)
FIXUP(BOOT_CS16_INDEX)
FIXUP(BOOT_DS_INDEX)
/* fix up GDT entry for GDT, and GDT and IDT pointers */
data32
movl %eax, %ecx
data32
addl $ EXT(Gdt), %eax
data32
shld $16, %eax, %ebx
FIXUP(GDT_INDEX)
addr32
data32
movl %eax, EXT(Gdtr)+2
data32
addl $ EXT(Idt), %ecx
addr32
data32
movl %ecx, EXT(Idtr_prot)+2
/* %es = vector table segment for a while */
push %es
data32
subl %eax, %eax
mov %ax, %es
/* fix up GDT entries for bdb */
data32
movl $4*DEBUG_VECTOR, %esi
addr32
movl %es: 2(%esi), %eax /* actually movw to %ax */
data32
shll $4, %eax
data32
shld $16, %eax, %ebx
FIXUP(DB_CS_INDEX)
FIXUP(DB_CS16_INDEX)
FIXUP(DB_DS_INDEX)
/* Fetch entry points of bdb's protected mode trap handlers. These
* are stored at 2 before the corresponding entry points for real mode.
*/
data32
subl %ebx, %ebx
addr32
movl %es: (%esi), %ebx /* actually movw to %bx */
data32
subl %ecx, %ecx
addr32
movl %es: 4*(BREAKPOINT_VECTOR-DEBUG_VECTOR)(%esi), %ecx
/* actually movw to %cx */
/* %es = bdb segment for a while */
data32
shrl $4, %eax
mov %ax, %es
/* fix up IDT entries for bdb */
subl $2, %ebx
movl %es: (%ebx), %eax /* actually movw to %ax */
addr32
movl %eax, EXT(Idt)+8*DEBUG_VECTOR /* actually movw %ax */
subl $2, %ecx
movl %es: (%ecx), %eax /* actually movw to %ax */
addr32
movl %eax, EXT(Idt)+8*BREAKPOINT_VECTOR /* actually movw %ax */
/* finished with groping in real mode segments */
pop %es
/* change to protected mode */
data32
call EXT(real_to_prot)
/* clear the bss */
movl $ EXT(edata), %edi /* no EXT(_edata) - krufty ld */
movl $ EXT(end), %ecx /* or EXT(_end) */
subl %edi, %ecx
subb %al, %al
rep
stosb
movzbl %dl, %edx /* discard head (%dh) and random high bits */
pushl %edx
call EXT(boot)
oops:
hlt
jmp oops
.data
.align 2
#if 0 /* XXX this would give losing "_ouraddr :". Better declared in C */
EXT(ouraddr):
#else
_ouraddr:
#endif
.long 0