fe2fc83936
When CONFIG_VBOOT_VBNV_CMOS_BACKUP_TO_FLASH is set, vbnv_cmos will try to load VBNV from flash if the VBNV in CMOS is invalid. This is usually correct, except the case of battery cut-off. CMOS will always be invalid after battery cut-off if there is no RTC battery (or if that is dead). However, in current implementation the backup in flash is only updated in coreboot, while the real battery cutoff (and the clearing of cutoff flags in VBNV) is done in payload (Depthcharge) stage. This will create an endless reboot loop that: 1. crossystem sets battery cutoff flag in VBNV_CMOS then reboot. 2. coreboot backs-up VBNV_CMOS to VBNV_flash. 3. Depthcharge sees cutoff flag in VBNV_CMOS. 4. Depthcharge clears cutoff flag in VBNV_CMOS. 5. Depthcharge performs battery cutoff (CMOS data is lost). 6. (Plug AC adapter) Reboot. 7. Coreboot sees invalid VBNV_CMOS, load backup from VBNV_flash. 8. Jump to 3. As a result, we should always clear battery cutoff flags when loading backups from VBNV_flash. BRANCH=glados,reef BUG=chrome-os-partner:61365,chrome-os-partner:59615 TEST=emerge-reef coreboot bootimage; Change-Id: I3250a3a179a7b0de9c6e401e4a94dcd23920e473 Signed-off-by: Hung-Te Lin <hungte@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/423460 Reviewed-by: Duncan Laurie <dlaurie@google.com> Reviewed-on: https://review.coreboot.org/18008 Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> Tested-by: build bot (Jenkins) Reviewed-by: Martin Roth <martinroth@google.com>
96 lines
2.7 KiB
C
96 lines
2.7 KiB
C
/*
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* This file is part of the coreboot project.
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*
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* Copyright (C) 2011 The ChromiumOS Authors. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <bootstate.h>
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#include <console/console.h>
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#include <types.h>
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#include <pc80/mc146818rtc.h>
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#include <vboot/vbnv.h>
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#include <vboot/vbnv_layout.h>
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static void clear_vbnv_battery_cutoff_flag(uint8_t *vbnv_copy)
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{
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/*
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* Currently battery cutoff is done in payload stage, which does not
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* update backup VBNV. And doing battery cutoff will invalidate CMOS.
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* This means for every reboot after cutoff, read_vbnv_cmos will reload
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* backup VBNV and try to cutoff again, causing endless reboot loop.
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* So we should always clear battery cutoff flag from loaded backup.
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*/
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if (vbnv_copy[MISC_FLAGS_OFFSET] & MISC_FLAGS_BATTERY_CUTOFF_MASK) {
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printk(BIOS_INFO, "VBNV: Remove battery cut-off request.\n");
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vbnv_copy[MISC_FLAGS_OFFSET] &= ~MISC_FLAGS_BATTERY_CUTOFF_MASK;
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regen_vbnv_crc(vbnv_copy);
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}
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}
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void read_vbnv_cmos(uint8_t *vbnv_copy)
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{
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int i;
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for (i = 0; i < VBOOT_VBNV_BLOCK_SIZE; i++)
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vbnv_copy[i] = cmos_read(CONFIG_VBOOT_VBNV_OFFSET + 14 + i);
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if (IS_ENABLED(CONFIG_VBOOT_VBNV_CMOS_BACKUP_TO_FLASH)) {
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if (verify_vbnv(vbnv_copy))
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return;
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printk(BIOS_INFO, "VBNV: CMOS invalid, restoring from flash\n");
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read_vbnv_flash(vbnv_copy);
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if (verify_vbnv(vbnv_copy)) {
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clear_vbnv_battery_cutoff_flag(vbnv_copy);
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save_vbnv_cmos(vbnv_copy);
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printk(BIOS_INFO, "VBNV: Flash backup restored\n");
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} else {
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printk(BIOS_INFO, "VBNV: Restore from flash failed\n");
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}
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}
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}
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void save_vbnv_cmos(const uint8_t *vbnv_copy)
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{
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int i;
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for (i = 0; i < VBOOT_VBNV_BLOCK_SIZE; i++)
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cmos_write(vbnv_copy[i], CONFIG_VBOOT_VBNV_OFFSET + 14 + i);
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}
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void init_vbnv_cmos(int rtc_fail)
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{
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uint8_t vbnv[VBOOT_VBNV_BLOCK_SIZE];
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if (rtc_fail)
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read_vbnv_cmos(vbnv);
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cmos_init(rtc_fail);
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if (rtc_fail)
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save_vbnv_cmos(vbnv);
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}
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#if IS_ENABLED(CONFIG_VBOOT_VBNV_CMOS_BACKUP_TO_FLASH)
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static void back_up_vbnv_cmos(void *unused)
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{
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uint8_t vbnv_cmos[VBOOT_VBNV_BLOCK_SIZE];
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/* Read current VBNV from CMOS. */
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read_vbnv_cmos(vbnv_cmos);
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/* Save to flash, will only be saved if different. */
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save_vbnv_flash(vbnv_cmos);
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}
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BOOT_STATE_INIT_ENTRY(BS_POST_DEVICE, BS_ON_EXIT, back_up_vbnv_cmos, NULL);
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#endif
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