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  */
  30 static 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.  */
  72 int 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.  */
  86 void 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.  */
 115 void boot_sector_cleanup(const char *fname)
 116 {
 117     unlink(fname);
 118 }