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/* $OpenBSD: mbr.S,v 1.1 2006/10/06 21:48:50 mickey Exp $ */
/* $NetBSD: mbr.S,v 1.1 2006/09/01 21:26:19 uwe Exp $ */
/*-
* Copyright (c) 2005 NONAKA Kimihiro
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <machine/asm.h>
ENTRY(start)
mova mbr_end, r0
mov r0, r11 /* r11: relocate address */
mov.w mbr_size, r2
sub r2, r0
mov r0, r10 /* r10: loaded address */
mov.w stack_offset, r1
add r1, r0
mov r0, r15 /* r15: stack pointer */
/* relocate code */
mova jmp_start, r0
mov r0, r13
add r2, r13 /* calc jump address */
mov r10, r0
mov r11, r1
1: mov.b @r0+, r3
dt r2
mov.b r3, @r1
bf/s 1b
add #1, r1
jmp @r13
nop
.align 2
jmp_start:
/* enable cache */
mov #0, r4
mov #6, r0
trapa #0x3f
/* print banner */
mova banner, r0
bsr message
mov r0, r4
/* search bootable partition */
mov.w part_offset, r12
add r11, r12 /* r12: pointer to partition entry */
mov #4, r8 /* r8: partition loop counter */
loop_part:
mov.b @(4, r12), r0
cmp/eq #0x00, r0
bt next_part
/* check active partition */
mov.b @(0, r12), r0
cmp/eq #0x80, r0
bf next_part
/* found bootable partition */
mov.w @(8, r12), r0 /* load unaligned 32bit data */
mov r0, r1
mov.w @(10, r12), r0
extu.w r1, r1
shll16 r0
or r1, r0
mov r0, r3
mova found_sector, r0
bra boot_lba
mov.l r3, @r0
next_part:
dt r8
bf/s loop_part
add #16, r12
noos_error:
/* Not found bootable partition */
mova ERR_NOOS, r0
error:
bsr message
mov r0, r4
99: bra 99b
nop
read_error:
bra error
mova ERR_READ, r0
message:
mov #32, r0
trapa #0x3f
rts
nop
read_sector_lba:
mov #1, r7
mov #2, r0
trapa #0x3f
tst r0, r0
bf read_error
rts
nop
boot_lba:
/* read PBR sector */
mova found_sector, r0
mov #0x40, r4
mov.l @r0, r5
bsr read_sector_lba
mov r10, r6
/* flush cache */
mov #0, r4
mov #6, r0
trapa #0x3f
/* check signature */
mov.b @(0, r10), r0
tst r0, r0
bt noos_error /* first byte non-zero */
mov.w magic_offset, r0
mov.w @(r0, r10), r1
mov.w magic, r2
cmp/eq r1, r2
bf noos_error /* magic */
/* now jump to PBR */
mov r10, r0
jmp @r10
nop
.align 1
mbr_size: .word mbr_end - _C_LABEL(start)
.align 1
stack_offset: .word 0x1000
.align 1
part_offset: .word 0x1be
.align 1
magic_offset: .word 0x1fe
.align 2
found_sector: .long 0
.align 2
banner: .asciz "\r\nOpenBSD MBR\r\n"
.align 2
ERR_INVPART: .asciz "No active partition\r\n"
.align 2
ERR_READ: .asciz "Read error\r\n"
.align 2
ERR_NOOS: .asciz "No O/S\r\n"
/* space for mbr_dsn */
. = _C_LABEL(start) + 0x1b4
.long 0
/* mbr_bootsel_magic */
. = _C_LABEL(start) + 0x1b8
.word 0
/*
* MBR partition table
*/
. = _C_LABEL(start) + 0x1be
_pbr_part0:
.byte 0, 0, 0, 0, 0, 0, 0, 0
.byte 0, 0, 0, 0, 0, 0, 0, 0
_pbr_part1:
.byte 0, 0, 0, 0, 0, 0, 0, 0
.byte 0, 0, 0, 0, 0, 0, 0, 0
_pbr_part2:
.byte 0, 0, 0, 0, 0, 0, 0, 0
.byte 0, 0, 0, 0, 0, 0, 0, 0
_pbr_part3:
.byte 0x80, 0, 1, 0, 0xa6, 255, 255, 255
.word 0, 0, 0xffff, 0x7fff
. = _C_LABEL(start) + 0x1fe
magic:
.word 0xaa55
mbr_end:
|
