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/* SPDX-License-Identifier: GPL-2.0-only */
/* This file is part of the coreboot project. */
#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 (!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 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
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