There are currently two bugs in s390x_code[]: First, the initial jump uses the wrong offset, so it was jumping to 0x10014 instead of 0x10010. Second, LHI only loads the lower 32-bit of the register. Everything worked fine as long as the s390-ccw bios code was jumping here with r3 containing zeroes in the uppermost 48 bit - which just happened to be the case so far by accident. But we can not rely on this fact, and indeed one of the recent suggested patches to jump2ipl.c cause the newer GCCs to put different values into r3. In that case the code from s390x_code[] crashes very ungracefully. Thus let's make sure to jump to the right instruction, and use LGHI instead of LHI to make sure that we always zero out the upper bits of the register. Signed-off-by: Thomas Huth <thuth@redhat.com> Message-Id: <20191217150642.27946-1-thuth@redhat.com> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Cornelia Huck <cohuck@redhat.com>
169 lines
5.1 KiB
C
169 lines
5.1 KiB
C
/*
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* QEMU boot sector testing helpers.
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*
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* Copyright (c) 2016 Red Hat Inc.
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*
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* Authors:
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* Michael S. Tsirkin <mst@redhat.com>
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* Victor Kaplansky <victork@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#include "qemu/osdep.h"
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#include "boot-sector.h"
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#include "qemu-common.h"
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#include "libqtest.h"
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#define LOW(x) ((x) & 0xff)
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#define HIGH(x) ((x) >> 8)
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#define SIGNATURE 0xdead
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#define SIGNATURE_OFFSET 0x10
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#define BOOT_SECTOR_ADDRESS 0x7c00
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#define SIGNATURE_ADDR (BOOT_SECTOR_ADDRESS + SIGNATURE_OFFSET)
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/* x86 boot sector code: write SIGNATURE into memory,
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* then halt.
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*/
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static uint8_t x86_boot_sector[512] = {
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/* The first sector will be placed at RAM address 00007C00, and
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* the BIOS transfers control to 00007C00
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*/
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/* Data Segment register should be initialized, since pxe
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* boot loader can leave it dirty.
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*/
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/* 7c00: move $0000,%ax */
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[0x00] = 0xb8,
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[0x01] = 0x00,
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[0x02] = 0x00,
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/* 7c03: move %ax,%ds */
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[0x03] = 0x8e,
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[0x04] = 0xd8,
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/* 7c05: mov $0xdead,%ax */
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[0x05] = 0xb8,
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[0x06] = LOW(SIGNATURE),
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[0x07] = HIGH(SIGNATURE),
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/* 7c08: mov %ax,0x7c10 */
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[0x08] = 0xa3,
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[0x09] = LOW(SIGNATURE_ADDR),
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[0x0a] = HIGH(SIGNATURE_ADDR),
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/* 7c0b cli */
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[0x0b] = 0xfa,
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/* 7c0c: hlt */
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[0x0c] = 0xf4,
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/* 7c0e: jmp 0x7c07=0x7c0f-3 */
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[0x0d] = 0xeb,
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[0x0e] = LOW(-3),
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/* We mov 0xdead here: set value to make debugging easier */
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[SIGNATURE_OFFSET] = LOW(0xface),
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[SIGNATURE_OFFSET + 1] = HIGH(0xface),
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/* End of boot sector marker */
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[0x1FE] = 0x55,
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[0x1FF] = 0xAA,
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};
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/* For s390x, use a mini "kernel" with the appropriate signature */
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static const uint8_t s390x_psw_and_magic[] = {
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0x00, 0x08, 0x00, 0x00, 0x80, 0x01, 0x00, 0x00, /* Program status word */
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0x02, 0x00, 0x00, 0x18, 0x60, 0x00, 0x00, 0x50, /* Magic: */
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0x02, 0x00, 0x00, 0x68, 0x60, 0x00, 0x00, 0x50, /* see linux_s390_magic */
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0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40 /* in the s390-ccw bios */
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};
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static const uint8_t s390x_code[] = {
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0xa7, 0xf4, 0x00, 0x08, /* j 0x10010 */
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0x00, 0x00, 0x00, 0x00,
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'S', '3', '9', '0',
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'E', 'P', 0x00, 0x01,
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0xa7, 0x39, HIGH(SIGNATURE_ADDR), LOW(SIGNATURE_ADDR), /* lghi r3,0x7c10 */
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0xa7, 0x48, LOW(SIGNATURE), HIGH(SIGNATURE), /* lhi r4,0xadde */
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0x40, 0x40, 0x30, 0x00, /* sth r4,0(r3) */
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0xa7, 0xf4, 0xff, 0xfa /* j 0x10010 */
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};
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/* Create boot disk file. */
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int boot_sector_init(char *fname)
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{
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int fd, ret;
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size_t len;
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char *boot_code;
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const char *arch = qtest_get_arch();
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fd = mkstemp(fname);
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if (fd < 0) {
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fprintf(stderr, "Couldn't open \"%s\": %s", fname, strerror(errno));
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return 1;
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}
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if (g_str_equal(arch, "i386") || g_str_equal(arch, "x86_64")) {
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/* Q35 requires a minimum 0x7e000 bytes disk (bug or feature?) */
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len = MAX(0x7e000, sizeof(x86_boot_sector));
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boot_code = g_malloc0(len);
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memcpy(boot_code, x86_boot_sector, sizeof(x86_boot_sector));
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} else if (g_str_equal(arch, "ppc64")) {
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/* For Open Firmware based system, use a Forth script */
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boot_code = g_strdup_printf("\\ Bootscript\n%x %x c! %x %x c!\n",
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LOW(SIGNATURE), SIGNATURE_ADDR,
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HIGH(SIGNATURE), SIGNATURE_ADDR + 1);
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len = strlen(boot_code);
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} else if (g_str_equal(arch, "s390x")) {
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len = 0x10000 + sizeof(s390x_code);
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boot_code = g_malloc0(len);
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memcpy(boot_code, s390x_psw_and_magic, sizeof(s390x_psw_and_magic));
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memcpy(&boot_code[0x10000], s390x_code, sizeof(s390x_code));
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} else {
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g_assert_not_reached();
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}
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ret = write(fd, boot_code, len);
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close(fd);
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g_free(boot_code);
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if (ret != len) {
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fprintf(stderr, "Could not write \"%s\"", fname);
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return 1;
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}
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return 0;
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}
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/* Loop until signature in memory is OK. */
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void boot_sector_test(QTestState *qts)
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{
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uint8_t signature_low;
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uint8_t signature_high;
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uint16_t signature;
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int i;
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/* Wait at most 600 seconds (test is slow with TCI and --enable-debug) */
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#define TEST_DELAY (1 * G_USEC_PER_SEC / 10)
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#define TEST_CYCLES MAX((600 * G_USEC_PER_SEC / TEST_DELAY), 1)
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/* Poll until code has run and modified memory. Once it has we know BIOS
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* initialization is done. TODO: check that IP reached the halt
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* instruction.
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*/
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for (i = 0; i < TEST_CYCLES; ++i) {
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signature_low = qtest_readb(qts, SIGNATURE_ADDR);
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signature_high = qtest_readb(qts, SIGNATURE_ADDR + 1);
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signature = (signature_high << 8) | signature_low;
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if (signature == SIGNATURE) {
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break;
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}
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g_usleep(TEST_DELAY);
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}
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g_assert_cmphex(signature, ==, SIGNATURE);
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}
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/* unlink boot disk file. */
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void boot_sector_cleanup(const char *fname)
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{
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unlink(fname);
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}
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