diff options
Diffstat (limited to 'src/security/vboot/vbnv_cmos.c')
| -rw-r--r-- | src/security/vboot/vbnv_cmos.c | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/src/security/vboot/vbnv_cmos.c b/src/security/vboot/vbnv_cmos.c new file mode 100644 index 0000000000..9c801d84fe --- /dev/null +++ b/src/security/vboot/vbnv_cmos.c @@ -0,0 +1,114 @@ +/* + * This file is part of the coreboot project. + * + * Copyright (C) 2011 The ChromiumOS Authors. All rights reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <bootstate.h> +#include <console/console.h> +#include <types.h> +#include <pc80/mc146818rtc.h> +#include <security/vboot/vbnv.h> +#include <security/vboot/vbnv_layout.h> + +static void clear_vbnv_battery_cutoff_flag(uint8_t *vbnv_copy) +{ + /* + * Currently battery cutoff is done in payload stage, which does not + * update backup VBNV. And doing battery cutoff will invalidate CMOS. + * This means for every reboot after cutoff, read_vbnv_cmos will reload + * backup VBNV and try to cutoff again, causing endless reboot loop. + * So we should always clear battery cutoff flag from loaded backup. + */ + if (vbnv_copy[MISC_FLAGS_OFFSET] & MISC_FLAGS_BATTERY_CUTOFF_MASK) { + printk(BIOS_INFO, "VBNV: Remove battery cut-off request.\n"); + vbnv_copy[MISC_FLAGS_OFFSET] &= ~MISC_FLAGS_BATTERY_CUTOFF_MASK; + regen_vbnv_crc(vbnv_copy); + } +} + +/* Return non-zero if backup was used. */ +static int restore_from_backup(uint8_t *vbnv_copy) +{ + if (!IS_ENABLED(CONFIG_VBOOT_VBNV_CMOS_BACKUP_TO_FLASH)) + return 0; + + printk(BIOS_INFO, "VBNV: CMOS invalid, restoring from flash\n"); + read_vbnv_flash(vbnv_copy); + + if (verify_vbnv(vbnv_copy)) { + clear_vbnv_battery_cutoff_flag(vbnv_copy); + save_vbnv_cmos(vbnv_copy); + printk(BIOS_INFO, "VBNV: Flash backup restored\n"); + return 1; + } + + printk(BIOS_INFO, "VBNV: Restore from flash failed\n"); + + return 0; +} + +void read_vbnv_cmos(uint8_t *vbnv_copy) +{ + int i; + + for (i = 0; i < VBOOT_VBNV_BLOCK_SIZE; i++) + vbnv_copy[i] = cmos_read(CONFIG_VBOOT_VBNV_OFFSET + 14 + i); + + /* Verify contents before attempting a restore from backup storage. */ + if (verify_vbnv(vbnv_copy)) + return; + + restore_from_backup(vbnv_copy); +} + +void save_vbnv_cmos(const uint8_t *vbnv_copy) +{ + int i; + + for (i = 0; i < VBOOT_VBNV_BLOCK_SIZE; i++) + cmos_write(vbnv_copy[i], CONFIG_VBOOT_VBNV_OFFSET + 14 + i); +} + +void vbnv_init_cmos(uint8_t *vbnv_copy) +{ + /* If no cmos failure just defer to the normal read path for checking + vbnv contents' integrity. */ + if (!vbnv_cmos_failed()) + return; + + /* In the case of cmos failure force the backup. If backup wasn't used + force the vbnv cmos to be reset. */ + if (!restore_from_backup(vbnv_copy)) { + vbnv_reset(vbnv_copy); + /* This parallels the vboot_reference implementation. */ + vbnv_copy[HEADER_OFFSET] = HEADER_SIGNATURE | + HEADER_FIRMWARE_SETTINGS_RESET | + HEADER_KERNEL_SETTINGS_RESET; + regen_vbnv_crc(vbnv_copy); + save_vbnv_cmos(vbnv_copy); + } +} + +#if IS_ENABLED(CONFIG_VBOOT_VBNV_CMOS_BACKUP_TO_FLASH) +static void back_up_vbnv_cmos(void *unused) +{ + uint8_t vbnv_cmos[VBOOT_VBNV_BLOCK_SIZE]; + + /* Read current VBNV from CMOS. */ + read_vbnv_cmos(vbnv_cmos); + + /* Save to flash, will only be saved if different. */ + save_vbnv_flash(vbnv_cmos); +} +BOOT_STATE_INIT_ENTRY(BS_POST_DEVICE, BS_ON_EXIT, back_up_vbnv_cmos, NULL); +#endif |