1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
|
/*
* QEMU boot sector testing helpers.
*
* Copyright (c) 2016 Red Hat Inc.
*
* Authors:
* Michael S. Tsirkin <mst@redhat.com>
* Victor Kaplansky <victork@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "boot-sector.h"
#include <string.h>
#include <stdio.h>
#include "qemu-common.h"
#include "libqtest.h"
#define LOW(x) ((x) & 0xff)
#define HIGH(x) ((x) >> 8)
#define SIGNATURE 0xdead
#define SIGNATURE_OFFSET 0x10
#define BOOT_SECTOR_ADDRESS 0x7c00
/* Boot sector code: write SIGNATURE into memory,
* then halt.
* Q35 machine requires a minimum 0x7e000 bytes disk.
* (bug or feature?)
*/
static uint8_t boot_sector[0x7e000] = {
/* The first sector will be placed at RAM address 00007C00, and
* the BIOS transfers control to 00007C00
*/
/* Data Segment register should be initialized, since pxe
* boot loader can leave it dirty.
*/
/* 7c00: move $0000,%ax */
[0x00] = 0xb8,
[0x01] = 0x00,
[0x02] = 0x00,
/* 7c03: move %ax,%ds */
[0x03] = 0x8e,
[0x04] = 0xd8,
/* 7c05: mov $0xdead,%ax */
[0x05] = 0xb8,
[0x06] = LOW(SIGNATURE),
[0x07] = HIGH(SIGNATURE),
/* 7c08: mov %ax,0x7c10 */
[0x08] = 0xa3,
[0x09] = LOW(BOOT_SECTOR_ADDRESS + SIGNATURE_OFFSET),
[0x0a] = HIGH(BOOT_SECTOR_ADDRESS + SIGNATURE_OFFSET),
/* 7c0b cli */
[0x0b] = 0xfa,
/* 7c0c: hlt */
[0x0c] = 0xf4,
/* 7c0e: jmp 0x7c07=0x7c0f-3 */
[0x0d] = 0xeb,
[0x0e] = LOW(-3),
/* We mov 0xdead here: set value to make debugging easier */
[SIGNATURE_OFFSET] = LOW(0xface),
[SIGNATURE_OFFSET + 1] = HIGH(0xface),
/* End of boot sector marker */
[0x1FE] = 0x55,
[0x1FF] = 0xAA,
};
/* Create boot disk file. */
int boot_sector_init(const char *fname)
{
FILE *f = fopen(fname, "w");
if (!f) {
fprintf(stderr, "Couldn't open \"%s\": %s", fname, strerror(errno));
return 1;
}
fwrite(boot_sector, 1, sizeof boot_sector, f);
fclose(f);
return 0;
}
/* Loop until signature in memory is OK. */
void boot_sector_test(void)
{
uint8_t signature_low;
uint8_t signature_high;
uint16_t signature;
int i;
/* Wait at most 1 minute */
#define TEST_DELAY (1 * G_USEC_PER_SEC / 10)
#define TEST_CYCLES MAX((60 * G_USEC_PER_SEC / TEST_DELAY), 1)
/* Poll until code has run and modified memory. Once it has we know BIOS
* initialization is done. TODO: check that IP reached the halt
* instruction.
*/
for (i = 0; i < TEST_CYCLES; ++i) {
signature_low = readb(BOOT_SECTOR_ADDRESS + SIGNATURE_OFFSET);
signature_high = readb(BOOT_SECTOR_ADDRESS + SIGNATURE_OFFSET + 1);
signature = (signature_high << 8) | signature_low;
if (signature == SIGNATURE) {
break;
}
g_usleep(TEST_DELAY);
}
g_assert_cmphex(signature, ==, SIGNATURE);
}
/* unlink boot disk file. */
void boot_sector_cleanup(const char *fname)
{
unlink(fname);
}
|
