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