tests/boot-sector.c

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