firmware/lib/vboot_nvstorage.c - mirrors/cros/chromiumos/platform/vboot_reference - Git at Google

 /* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 /* Non-volatile storage routines.
  */
 #include "sysincludes.h"

 #include "2crc8.h"
 #include "utility.h"
 #include "vboot_common.h"
 #include "vboot_nvstorage.h"

 /*
  * Constants for NV storage.  We use this rather than structs and bitfields so
  * the data format is consistent across platforms and compilers.
  *
  * These constants must match the equivalent constants in 2lib/2nvstorage.c.
  * (We currently don't share a common header file because we're tring to keep
  * the two libs independent, and we hope to deprecate this one.)
  */
 #define HEADER_OFFSET                0
 #define HEADER_MASK                     0xC0
 #define HEADER_SIGNATURE                0x40
 #define HEADER_FIRMWARE_SETTINGS_RESET  0x20
 #define HEADER_KERNEL_SETTINGS_RESET    0x10
 #define HEADER_WIPEOUT			0x08

 #define BOOT_OFFSET                  1
 #define BOOT_DEBUG_RESET_MODE           0x80
 #define BOOT_DISABLE_DEV_REQUEST        0x40
 #define BOOT_OPROM_NEEDED               0x20
 #define BOOT_BACKUP_NVRAM               0x10
 #define BOOT_TRY_B_COUNT_MASK           0x0F

 #define RECOVERY_OFFSET              2
 #define LOCALIZATION_OFFSET          3

 #define DEV_FLAGS_OFFSET             4
 #define DEV_BOOT_USB_MASK               0x01
 #define DEV_BOOT_SIGNED_ONLY_MASK       0x02
 #define DEV_BOOT_LEGACY_MASK            0x04
 #define DEV_BOOT_FASTBOOT_FULL_CAP_MASK 0x08
 #define DEV_DEFAULT_BOOT_MASK           0x30
 #define DEV_DEFAULT_BOOT_SHIFT 4  /* Number of bits to shift */

 #define TPM_FLAGS_OFFSET             5
 #define TPM_CLEAR_OWNER_REQUEST         0x01
 #define TPM_CLEAR_OWNER_DONE            0x02
 #define TPM_REBOOTED                    0x04

 #define RECOVERY_SUBCODE_OFFSET      6

 #define BOOT2_OFFSET                 7
 #define BOOT2_RESULT_MASK               0x03
 #define BOOT2_TRIED                     0x04
 #define BOOT2_TRY_NEXT                  0x08
 #define BOOT2_PREV_RESULT_MASK          0x30
 #define BOOT2_PREV_RESULT_SHIFT 4  /* Number of bits to shift result */
 #define BOOT2_PREV_TRIED                0x40

 #define MISC_OFFSET                        8
 #define MISC_UNLOCK_FASTBOOT            0x01
 #define MISC_BOOT_ON_AC_DETECT          0x02
 #define MISC_TRY_RO_SYNC		0x04
 #define MISC_BATTERY_CUTOFF_REQUEST	0x08

 #define KERNEL_MAX_ROLLFORWARD1_OFFSET     9 /* Low bits */
 #define KERNEL_MAX_ROLLFORWARD2_OFFSET    10
 #define KERNEL_MAX_ROLLFORWARD3_OFFSET    13
 #define KERNEL_MAX_ROLLFORWARD4_OFFSET    14 /* High bits */

 #define KERNEL_FIELD1_OFFSET         11 /* Low bits */
 #define KERNEL_FIELD2_OFFSET         12 /* Low bits */

 #define CRC_OFFSET                  15

 int VbNvSetup(VbNvContext *context)
 {
 	uint8_t *raw = context->raw;

 	/* Nothing has changed yet. */
 	context->raw_changed = 0;
 	context->regenerate_crc = 0;

 	/* Check data for consistency */
 	if ((HEADER_SIGNATURE != (raw[HEADER_OFFSET] & HEADER_MASK))
 	    || (vb2_crc8(raw, CRC_OFFSET) != raw[CRC_OFFSET])) {
 		/* Data is inconsistent (bad CRC or header); reset defaults */
 		memset(raw, 0, VBNV_BLOCK_SIZE);
 		raw[HEADER_OFFSET] = (HEADER_SIGNATURE |
 				      HEADER_FIRMWARE_SETTINGS_RESET |
 				      HEADER_KERNEL_SETTINGS_RESET);

 		/* Regenerate CRC on exit */
 		context->regenerate_crc = 1;
 	}

 	return 0;
 }

 int VbNvTeardown(VbNvContext *context)
 {
 	if (context->regenerate_crc) {
 		context->raw[CRC_OFFSET] = vb2_crc8(context->raw, CRC_OFFSET);
 		context->regenerate_crc = 0;
 		context->raw_changed = 1;
 	}

 	return 0;
 }

 int VbNvGet(VbNvContext *context, VbNvParam param, uint32_t *dest)
 {
 	const uint8_t *raw = context->raw;

 	switch (param) {
 	case VBNV_FIRMWARE_SETTINGS_RESET:
 		*dest = (raw[HEADER_OFFSET] & HEADER_FIRMWARE_SETTINGS_RESET ?
 			 1 : 0);
 		return 0;

 	case VBNV_KERNEL_SETTINGS_RESET:
 		*dest = (raw[HEADER_OFFSET] & HEADER_KERNEL_SETTINGS_RESET ?
 			 1 : 0);
 		return 0;

 	case VBNV_DEBUG_RESET_MODE:
 		*dest = (raw[BOOT_OFFSET] & BOOT_DEBUG_RESET_MODE ? 1 : 0);
 		return 0;

 	case VBNV_TRY_B_COUNT:
 	case VBNV_FW_TRY_COUNT:
 		*dest = raw[BOOT_OFFSET] & BOOT_TRY_B_COUNT_MASK;
 		return 0;

 	case VBNV_RECOVERY_REQUEST:
 		*dest = raw[RECOVERY_OFFSET];
 		return 0;

 	case VBNV_RECOVERY_SUBCODE:
 		*dest = raw[RECOVERY_SUBCODE_OFFSET];
 		return 0;

 	case VBNV_LOCALIZATION_INDEX:
 		*dest = raw[LOCALIZATION_OFFSET];
 		return 0;

 	case VBNV_KERNEL_FIELD:
 		*dest = (raw[KERNEL_FIELD1_OFFSET]
 			 | (raw[KERNEL_FIELD2_OFFSET] << 8));
 		return 0;

 	case VBNV_DEV_BOOT_USB:
 		*dest = (raw[DEV_FLAGS_OFFSET] & DEV_BOOT_USB_MASK ? 1 : 0);
 		return 0;

 	case VBNV_DEV_BOOT_LEGACY:
 		*dest = (raw[DEV_FLAGS_OFFSET] & DEV_BOOT_LEGACY_MASK ? 1 : 0);
 		return 0;

 	case VBNV_DEV_DEFAULT_BOOT:
 		*dest = (raw[DEV_FLAGS_OFFSET] & DEV_DEFAULT_BOOT_MASK)
 			>> DEV_DEFAULT_BOOT_SHIFT;
 		return 0;

 	case VBNV_DEV_BOOT_SIGNED_ONLY:
 		*dest = (raw[DEV_FLAGS_OFFSET] & DEV_BOOT_SIGNED_ONLY_MASK ?
 			 1 : 0);
 		return 0;

 	case VBNV_DEV_BOOT_FASTBOOT_FULL_CAP:
 		*dest = (raw[DEV_FLAGS_OFFSET] & DEV_BOOT_FASTBOOT_FULL_CAP_MASK
 			 ? 1 : 0);
 		return 0;

 	case VBNV_DISABLE_DEV_REQUEST:
 		*dest = (raw[BOOT_OFFSET] & BOOT_DISABLE_DEV_REQUEST ? 1 : 0);
 		return 0;

 	case VBNV_OPROM_NEEDED:
 		*dest = (raw[BOOT_OFFSET] & BOOT_OPROM_NEEDED ? 1 : 0);
 		return 0;

 	case VBNV_CLEAR_TPM_OWNER_REQUEST:
 		*dest = (raw[TPM_FLAGS_OFFSET] & TPM_CLEAR_OWNER_REQUEST ?
 			 1 : 0);
 		return 0;

 	case VBNV_CLEAR_TPM_OWNER_DONE:
 		*dest = (raw[TPM_FLAGS_OFFSET] & TPM_CLEAR_OWNER_DONE ? 1 : 0);
 		return 0;

 	case VBNV_TPM_REQUESTED_REBOOT:
 		*dest = (raw[TPM_FLAGS_OFFSET] & TPM_REBOOTED ? 1 : 0);
 		return 0;

 	case VBNV_BACKUP_NVRAM_REQUEST:
 		*dest = (raw[BOOT_OFFSET] & BOOT_BACKUP_NVRAM ? 1 : 0);
 		return 0;

 	case VBNV_FW_TRY_NEXT:
 		*dest = (raw[BOOT2_OFFSET] & BOOT2_TRY_NEXT ? 1 : 0);
 		return 0;

 	case VBNV_FW_TRIED:
 		*dest = (raw[BOOT2_OFFSET] & BOOT2_TRIED ? 1 : 0);
 		return 0;

 	case VBNV_FW_RESULT:
 		*dest = raw[BOOT2_OFFSET] & BOOT2_RESULT_MASK;
 		return 0;

 	case VBNV_FW_PREV_TRIED:
 		*dest = (raw[BOOT2_OFFSET] & BOOT2_PREV_TRIED ? 1 : 0);
 		return 0;

 	case VBNV_FW_PREV_RESULT:
 		*dest = (raw[BOOT2_OFFSET] & BOOT2_PREV_RESULT_MASK)
 			>> BOOT2_PREV_RESULT_SHIFT;
 		return 0;

 	case VBNV_FW_REQ_WIPEOUT:
 		*dest = (raw[HEADER_OFFSET] & HEADER_WIPEOUT) ? 1 : 0;
 		return 0;

 	case VBNV_FASTBOOT_UNLOCK_IN_FW:
 		*dest = (raw[MISC_OFFSET] & MISC_UNLOCK_FASTBOOT) ? 1 : 0;
 		return 0;

 	case VBNV_BOOT_ON_AC_DETECT:
 		*dest = (raw[MISC_OFFSET] & MISC_BOOT_ON_AC_DETECT) ? 1 : 0;
 		return 0;

 	case VBNV_TRY_RO_SYNC:
 		*dest = (raw[MISC_OFFSET] & MISC_TRY_RO_SYNC) ? 1 : 0;
 		return 0;

 	case VBNV_BATTERY_CUTOFF_REQUEST:
 		*dest = (raw[MISC_OFFSET] & MISC_BATTERY_CUTOFF_REQUEST)
 			 ?  1 : 0;
 		return 0;

 	case VBNV_KERNEL_MAX_ROLLFORWARD:
 		*dest = (raw[KERNEL_MAX_ROLLFORWARD1_OFFSET]
 			 | (raw[KERNEL_MAX_ROLLFORWARD2_OFFSET] << 8)
 			 | (raw[KERNEL_MAX_ROLLFORWARD3_OFFSET] << 16)
 			 | (raw[KERNEL_MAX_ROLLFORWARD4_OFFSET] << 24));
 		return 0;

 	default:
 		return 1;
 	}
 }

 int VbNvSet(VbNvContext *context, VbNvParam param, uint32_t value)
 {
 	uint8_t *raw = context->raw;
 	uint32_t current;

 	/* If not changing the value, don't regenerate the CRC. */
 	if (0 == VbNvGet(context, param, &current) && current == value)
 		return 0;

 	switch (param) {
 	case VBNV_FIRMWARE_SETTINGS_RESET:
 		if (value)
 			raw[HEADER_OFFSET] |= HEADER_FIRMWARE_SETTINGS_RESET;
 		else
 			raw[HEADER_OFFSET] &= ~HEADER_FIRMWARE_SETTINGS_RESET;
 		break;

 	case VBNV_KERNEL_SETTINGS_RESET:
 		if (value)
 			raw[HEADER_OFFSET] |= HEADER_KERNEL_SETTINGS_RESET;
 		else
 			raw[HEADER_OFFSET] &= ~HEADER_KERNEL_SETTINGS_RESET;
 		break;

 	case VBNV_DEBUG_RESET_MODE:
 		if (value)
 			raw[BOOT_OFFSET] |= BOOT_DEBUG_RESET_MODE;
 		else
 			raw[BOOT_OFFSET] &= ~BOOT_DEBUG_RESET_MODE;
 		break;

 	case VBNV_TRY_B_COUNT:
 	case VBNV_FW_TRY_COUNT:
 		/* Clip to valid range. */
 		if (value > BOOT_TRY_B_COUNT_MASK)
 			value = BOOT_TRY_B_COUNT_MASK;

 		raw[BOOT_OFFSET] &= ~BOOT_TRY_B_COUNT_MASK;
 		raw[BOOT_OFFSET] |= (uint8_t)value;
 		break;

 	case VBNV_RECOVERY_REQUEST:
 		/*
 		 * Map values outside the valid range to the legacy reason,
 		 * since we can't determine if we're called from kernel or user
 		 * mode.
 		 */
 		if (value > 0xFF)
 			value = VBNV_RECOVERY_LEGACY;
 		raw[RECOVERY_OFFSET] = (uint8_t)value;
 		break;

 	case VBNV_RECOVERY_SUBCODE:
 		raw[RECOVERY_SUBCODE_OFFSET] = (uint8_t)value;
 		break;

 	case VBNV_LOCALIZATION_INDEX:
 		/* Map values outside the valid range to the default index. */
 		if (value > 0xFF)
 			value = 0;
 		raw[LOCALIZATION_OFFSET] = (uint8_t)value;
 		break;

 	case VBNV_KERNEL_FIELD:
 		raw[KERNEL_FIELD1_OFFSET] = (uint8_t)(value);
 		raw[KERNEL_FIELD2_OFFSET] = (uint8_t)(value >> 8);
 		break;

 	case VBNV_DEV_BOOT_USB:
 		if (value)
 			raw[DEV_FLAGS_OFFSET] |= DEV_BOOT_USB_MASK;
 		else
 			raw[DEV_FLAGS_OFFSET] &= ~DEV_BOOT_USB_MASK;
 		break;

 	case VBNV_DEV_BOOT_LEGACY:
 		if (value)
 			raw[DEV_FLAGS_OFFSET] |= DEV_BOOT_LEGACY_MASK;
 		else
 			raw[DEV_FLAGS_OFFSET] &= ~DEV_BOOT_LEGACY_MASK;
 		break;

 	case VBNV_DEV_DEFAULT_BOOT:
 		/* Map out of range values to boot disk */
 		if (value > (DEV_DEFAULT_BOOT_MASK >>
 			     DEV_DEFAULT_BOOT_SHIFT))
 			value = VBNV_DEV_DEFAULT_BOOT_DISK;

 		raw[DEV_FLAGS_OFFSET] &= ~DEV_DEFAULT_BOOT_MASK;
 		raw[DEV_FLAGS_OFFSET] |= (uint8_t)value <<
 			DEV_DEFAULT_BOOT_SHIFT;
 		break;

 	case VBNV_DEV_BOOT_SIGNED_ONLY:
 		if (value)
 			raw[DEV_FLAGS_OFFSET] |= DEV_BOOT_SIGNED_ONLY_MASK;
 		else
 			raw[DEV_FLAGS_OFFSET] &= ~DEV_BOOT_SIGNED_ONLY_MASK;
 		break;

 	case VBNV_DEV_BOOT_FASTBOOT_FULL_CAP:
 		if (value)
 			raw[DEV_FLAGS_OFFSET] |=
 				DEV_BOOT_FASTBOOT_FULL_CAP_MASK;
 		else
 			raw[DEV_FLAGS_OFFSET] &=
 				~DEV_BOOT_FASTBOOT_FULL_CAP_MASK;
 		break;

 	case VBNV_DISABLE_DEV_REQUEST:
 		if (value)
 			raw[BOOT_OFFSET] |= BOOT_DISABLE_DEV_REQUEST;
 		else
 			raw[BOOT_OFFSET] &= ~BOOT_DISABLE_DEV_REQUEST;
 		break;

 	case VBNV_OPROM_NEEDED:
 		if (value)
 			raw[BOOT_OFFSET] |= BOOT_OPROM_NEEDED;
 		else
 			raw[BOOT_OFFSET] &= ~BOOT_OPROM_NEEDED;
 		break;

 	case VBNV_CLEAR_TPM_OWNER_REQUEST:
 		if (value)
 			raw[TPM_FLAGS_OFFSET] |= TPM_CLEAR_OWNER_REQUEST;
 		else
 			raw[TPM_FLAGS_OFFSET] &= ~TPM_CLEAR_OWNER_REQUEST;
 		break;

 	case VBNV_CLEAR_TPM_OWNER_DONE:
 		if (value)
 			raw[TPM_FLAGS_OFFSET] |= TPM_CLEAR_OWNER_DONE;
 		else
 			raw[TPM_FLAGS_OFFSET] &= ~TPM_CLEAR_OWNER_DONE;
 		break;

 	case VBNV_TPM_REQUESTED_REBOOT:
 		if (value)
 			raw[TPM_FLAGS_OFFSET] |= TPM_REBOOTED;
 		else
 			raw[TPM_FLAGS_OFFSET] &= ~TPM_REBOOTED;
 		break;

 	case VBNV_BACKUP_NVRAM_REQUEST:
 		if (value)
 			raw[BOOT_OFFSET] |= BOOT_BACKUP_NVRAM;
 		else
 			raw[BOOT_OFFSET] &= ~BOOT_BACKUP_NVRAM;
 		break;

 	case VBNV_FW_TRY_NEXT:
 		if (value)
 			raw[BOOT2_OFFSET] |= BOOT2_TRY_NEXT;
 		else
 			raw[BOOT2_OFFSET] &= ~BOOT2_TRY_NEXT;
 		break;

 	case VBNV_FW_TRIED:
 		if (value)
 			raw[BOOT2_OFFSET] |= BOOT2_TRIED;
 		else
 			raw[BOOT2_OFFSET] &= ~BOOT2_TRIED;
 		break;

 	case VBNV_FW_RESULT:
 		/* Map out of range values to unknown */
 		if (value > BOOT2_RESULT_MASK)
 			value = VBNV_FW_RESULT_UNKNOWN;

 		raw[BOOT2_OFFSET] &= ~BOOT2_RESULT_MASK;
 		raw[BOOT2_OFFSET] |= (uint8_t)value;
 		break;

 	case VBNV_FW_PREV_TRIED:
 		if (value)
 			raw[BOOT2_OFFSET] |= BOOT2_PREV_TRIED;
 		else
 			raw[BOOT2_OFFSET] &= ~BOOT2_PREV_TRIED;
 		break;

 	case VBNV_FW_PREV_RESULT:
 		/* Map out of range values to unknown */
 		if (value > BOOT2_RESULT_MASK)
 			value = VBNV_FW_RESULT_UNKNOWN;

 		raw[BOOT2_OFFSET] &= ~BOOT2_PREV_RESULT_MASK;
 		raw[BOOT2_OFFSET] |= (uint8_t)value << BOOT2_PREV_RESULT_SHIFT;
 		break;

 	case VBNV_FW_REQ_WIPEOUT:
 		if (value)
 			raw[HEADER_OFFSET] |= HEADER_WIPEOUT;
 		else
 			raw[HEADER_OFFSET] &= ~HEADER_WIPEOUT;
 		break;

 	case VBNV_FASTBOOT_UNLOCK_IN_FW:
 		if (value)
 			raw[MISC_OFFSET] |= MISC_UNLOCK_FASTBOOT;
 		else
 			raw[MISC_OFFSET] &= ~MISC_UNLOCK_FASTBOOT;
 		break;

 	case VBNV_BOOT_ON_AC_DETECT:
 		if (value)
 			raw[MISC_OFFSET] |= MISC_BOOT_ON_AC_DETECT;
 		else
 			raw[MISC_OFFSET] &= ~MISC_BOOT_ON_AC_DETECT;
 		break;

 	case VBNV_TRY_RO_SYNC:
 		if (value)
 			raw[MISC_OFFSET] |= MISC_TRY_RO_SYNC;
 		else
 			raw[MISC_OFFSET] &= ~MISC_TRY_RO_SYNC;
 		break;

 	case VBNV_BATTERY_CUTOFF_REQUEST:
 		if (value)
 			raw[MISC_OFFSET] |= MISC_BATTERY_CUTOFF_REQUEST;
 		else
 			raw[MISC_OFFSET] &= ~MISC_BATTERY_CUTOFF_REQUEST;
 		break;

 	case VBNV_KERNEL_MAX_ROLLFORWARD:
 		raw[KERNEL_MAX_ROLLFORWARD1_OFFSET] = (uint8_t)(value);
 		raw[KERNEL_MAX_ROLLFORWARD2_OFFSET] = (uint8_t)(value >> 8);
 		raw[KERNEL_MAX_ROLLFORWARD3_OFFSET] = (uint8_t)(value >> 16);
 		raw[KERNEL_MAX_ROLLFORWARD4_OFFSET] = (uint8_t)(value >> 24);
 		break;

 	default:
 		return 1;
 	}

 	/* Need to regenerate CRC, since the value changed. */
 	context->regenerate_crc = 1;
 	return 0;
 }
	/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	/* Non-volatile storage routines.
	*/
	#include "sysincludes.h"

	#include "2crc8.h"
	#include "utility.h"
	#include "vboot_common.h"
	#include "vboot_nvstorage.h"

	/*
	* Constants for NV storage. We use this rather than structs and bitfields so
	* the data format is consistent across platforms and compilers.
	*
	* These constants must match the equivalent constants in 2lib/2nvstorage.c.
	* (We currently don't share a common header file because we're tring to keep
	* the two libs independent, and we hope to deprecate this one.)
	*/
	#define HEADER_OFFSET 0
	#define HEADER_MASK 0xC0
	#define HEADER_SIGNATURE 0x40
	#define HEADER_FIRMWARE_SETTINGS_RESET 0x20
	#define HEADER_KERNEL_SETTINGS_RESET 0x10
	#define HEADER_WIPEOUT 0x08

	#define BOOT_OFFSET 1
	#define BOOT_DEBUG_RESET_MODE 0x80
	#define BOOT_DISABLE_DEV_REQUEST 0x40
	#define BOOT_OPROM_NEEDED 0x20
	#define BOOT_BACKUP_NVRAM 0x10
	#define BOOT_TRY_B_COUNT_MASK 0x0F

	#define RECOVERY_OFFSET 2
	#define LOCALIZATION_OFFSET 3

	#define DEV_FLAGS_OFFSET 4
	#define DEV_BOOT_USB_MASK 0x01
	#define DEV_BOOT_SIGNED_ONLY_MASK 0x02
	#define DEV_BOOT_LEGACY_MASK 0x04
	#define DEV_BOOT_FASTBOOT_FULL_CAP_MASK 0x08
	#define DEV_DEFAULT_BOOT_MASK 0x30
	#define DEV_DEFAULT_BOOT_SHIFT 4 /* Number of bits to shift */

	#define TPM_FLAGS_OFFSET 5
	#define TPM_CLEAR_OWNER_REQUEST 0x01
	#define TPM_CLEAR_OWNER_DONE 0x02
	#define TPM_REBOOTED 0x04

	#define RECOVERY_SUBCODE_OFFSET 6

	#define BOOT2_OFFSET 7
	#define BOOT2_RESULT_MASK 0x03
	#define BOOT2_TRIED 0x04
	#define BOOT2_TRY_NEXT 0x08
	#define BOOT2_PREV_RESULT_MASK 0x30
	#define BOOT2_PREV_RESULT_SHIFT 4 /* Number of bits to shift result */
	#define BOOT2_PREV_TRIED 0x40

	#define MISC_OFFSET 8
	#define MISC_UNLOCK_FASTBOOT 0x01
	#define MISC_BOOT_ON_AC_DETECT 0x02
	#define MISC_TRY_RO_SYNC 0x04
	#define MISC_BATTERY_CUTOFF_REQUEST 0x08

	#define KERNEL_MAX_ROLLFORWARD1_OFFSET 9 /* Low bits */
	#define KERNEL_MAX_ROLLFORWARD2_OFFSET 10
	#define KERNEL_MAX_ROLLFORWARD3_OFFSET 13
	#define KERNEL_MAX_ROLLFORWARD4_OFFSET 14 /* High bits */

	#define KERNEL_FIELD1_OFFSET 11 /* Low bits */
	#define KERNEL_FIELD2_OFFSET 12 /* Low bits */

	#define CRC_OFFSET 15

	int VbNvSetup(VbNvContext *context)
	{
	uint8_t *raw = context->raw;

	/* Nothing has changed yet. */
	context->raw_changed = 0;
	context->regenerate_crc = 0;

	/* Check data for consistency */
	if ((HEADER_SIGNATURE != (raw[HEADER_OFFSET] & HEADER_MASK))
	\|\| (vb2_crc8(raw, CRC_OFFSET) != raw[CRC_OFFSET])) {
	/* Data is inconsistent (bad CRC or header); reset defaults */
	memset(raw, 0, VBNV_BLOCK_SIZE);
	raw[HEADER_OFFSET] = (HEADER_SIGNATURE \|
	HEADER_FIRMWARE_SETTINGS_RESET \|
	HEADER_KERNEL_SETTINGS_RESET);

	/* Regenerate CRC on exit */
	context->regenerate_crc = 1;
	}

	return 0;
	}

	int VbNvTeardown(VbNvContext *context)
	{
	if (context->regenerate_crc) {
	context->raw[CRC_OFFSET] = vb2_crc8(context->raw, CRC_OFFSET);
	context->regenerate_crc = 0;
	context->raw_changed = 1;
	}

	return 0;
	}

	int VbNvGet(VbNvContext context, VbNvParam param, uint32_t dest)
	{
	const uint8_t *raw = context->raw;

	switch (param) {
	case VBNV_FIRMWARE_SETTINGS_RESET:
	*dest = (raw[HEADER_OFFSET] & HEADER_FIRMWARE_SETTINGS_RESET ?
	1 : 0);
	return 0;

	case VBNV_KERNEL_SETTINGS_RESET:
	*dest = (raw[HEADER_OFFSET] & HEADER_KERNEL_SETTINGS_RESET ?
	1 : 0);
	return 0;

	case VBNV_DEBUG_RESET_MODE:
	*dest = (raw[BOOT_OFFSET] & BOOT_DEBUG_RESET_MODE ? 1 : 0);
	return 0;

	case VBNV_TRY_B_COUNT:
	case VBNV_FW_TRY_COUNT:
	*dest = raw[BOOT_OFFSET] & BOOT_TRY_B_COUNT_MASK;
	return 0;

	case VBNV_RECOVERY_REQUEST:
	*dest = raw[RECOVERY_OFFSET];
	return 0;

	case VBNV_RECOVERY_SUBCODE:
	*dest = raw[RECOVERY_SUBCODE_OFFSET];
	return 0;

	case VBNV_LOCALIZATION_INDEX:
	*dest = raw[LOCALIZATION_OFFSET];
	return 0;

	case VBNV_KERNEL_FIELD:
	*dest = (raw[KERNEL_FIELD1_OFFSET]
	\| (raw[KERNEL_FIELD2_OFFSET] << 8));
	return 0;

	case VBNV_DEV_BOOT_USB:
	*dest = (raw[DEV_FLAGS_OFFSET] & DEV_BOOT_USB_MASK ? 1 : 0);
	return 0;

	case VBNV_DEV_BOOT_LEGACY:
	*dest = (raw[DEV_FLAGS_OFFSET] & DEV_BOOT_LEGACY_MASK ? 1 : 0);
	return 0;

	case VBNV_DEV_DEFAULT_BOOT:
	*dest = (raw[DEV_FLAGS_OFFSET] & DEV_DEFAULT_BOOT_MASK)
	>> DEV_DEFAULT_BOOT_SHIFT;
	return 0;

	case VBNV_DEV_BOOT_SIGNED_ONLY:
	*dest = (raw[DEV_FLAGS_OFFSET] & DEV_BOOT_SIGNED_ONLY_MASK ?
	1 : 0);
	return 0;

	case VBNV_DEV_BOOT_FASTBOOT_FULL_CAP:
	*dest = (raw[DEV_FLAGS_OFFSET] & DEV_BOOT_FASTBOOT_FULL_CAP_MASK
	? 1 : 0);
	return 0;

	case VBNV_DISABLE_DEV_REQUEST:
	*dest = (raw[BOOT_OFFSET] & BOOT_DISABLE_DEV_REQUEST ? 1 : 0);
	return 0;

	case VBNV_OPROM_NEEDED:
	*dest = (raw[BOOT_OFFSET] & BOOT_OPROM_NEEDED ? 1 : 0);
	return 0;

	case VBNV_CLEAR_TPM_OWNER_REQUEST:
	*dest = (raw[TPM_FLAGS_OFFSET] & TPM_CLEAR_OWNER_REQUEST ?
	1 : 0);
	return 0;

	case VBNV_CLEAR_TPM_OWNER_DONE:
	*dest = (raw[TPM_FLAGS_OFFSET] & TPM_CLEAR_OWNER_DONE ? 1 : 0);
	return 0;

	case VBNV_TPM_REQUESTED_REBOOT:
	*dest = (raw[TPM_FLAGS_OFFSET] & TPM_REBOOTED ? 1 : 0);
	return 0;

	case VBNV_BACKUP_NVRAM_REQUEST:
	*dest = (raw[BOOT_OFFSET] & BOOT_BACKUP_NVRAM ? 1 : 0);
	return 0;

	case VBNV_FW_TRY_NEXT:
	*dest = (raw[BOOT2_OFFSET] & BOOT2_TRY_NEXT ? 1 : 0);
	return 0;

	case VBNV_FW_TRIED:
	*dest = (raw[BOOT2_OFFSET] & BOOT2_TRIED ? 1 : 0);
	return 0;

	case VBNV_FW_RESULT:
	*dest = raw[BOOT2_OFFSET] & BOOT2_RESULT_MASK;
	return 0;

	case VBNV_FW_PREV_TRIED:
	*dest = (raw[BOOT2_OFFSET] & BOOT2_PREV_TRIED ? 1 : 0);
	return 0;

	case VBNV_FW_PREV_RESULT:
	*dest = (raw[BOOT2_OFFSET] & BOOT2_PREV_RESULT_MASK)
	>> BOOT2_PREV_RESULT_SHIFT;
	return 0;

	case VBNV_FW_REQ_WIPEOUT:
	*dest = (raw[HEADER_OFFSET] & HEADER_WIPEOUT) ? 1 : 0;
	return 0;

	case VBNV_FASTBOOT_UNLOCK_IN_FW:
	*dest = (raw[MISC_OFFSET] & MISC_UNLOCK_FASTBOOT) ? 1 : 0;
	return 0;

	case VBNV_BOOT_ON_AC_DETECT:
	*dest = (raw[MISC_OFFSET] & MISC_BOOT_ON_AC_DETECT) ? 1 : 0;
	return 0;

	case VBNV_TRY_RO_SYNC:
	*dest = (raw[MISC_OFFSET] & MISC_TRY_RO_SYNC) ? 1 : 0;
	return 0;

	case VBNV_BATTERY_CUTOFF_REQUEST:
	*dest = (raw[MISC_OFFSET] & MISC_BATTERY_CUTOFF_REQUEST)
	? 1 : 0;
	return 0;

	case VBNV_KERNEL_MAX_ROLLFORWARD:
	*dest = (raw[KERNEL_MAX_ROLLFORWARD1_OFFSET]
	\| (raw[KERNEL_MAX_ROLLFORWARD2_OFFSET] << 8)
	\| (raw[KERNEL_MAX_ROLLFORWARD3_OFFSET] << 16)
	\| (raw[KERNEL_MAX_ROLLFORWARD4_OFFSET] << 24));
	return 0;

	default:
	return 1;
	}
	}

	int VbNvSet(VbNvContext *context, VbNvParam param, uint32_t value)
	{
	uint8_t *raw = context->raw;
	uint32_t current;

	/* If not changing the value, don't regenerate the CRC. */
	if (0 == VbNvGet(context, param, &current) && current == value)
	return 0;

	switch (param) {
	case VBNV_FIRMWARE_SETTINGS_RESET:
	if (value)
	raw[HEADER_OFFSET] \|= HEADER_FIRMWARE_SETTINGS_RESET;
	else
	raw[HEADER_OFFSET] &= ~HEADER_FIRMWARE_SETTINGS_RESET;
	break;

	case VBNV_KERNEL_SETTINGS_RESET:
	if (value)
	raw[HEADER_OFFSET] \|= HEADER_KERNEL_SETTINGS_RESET;
	else
	raw[HEADER_OFFSET] &= ~HEADER_KERNEL_SETTINGS_RESET;
	break;

	case VBNV_DEBUG_RESET_MODE:
	if (value)
	raw[BOOT_OFFSET] \|= BOOT_DEBUG_RESET_MODE;
	else
	raw[BOOT_OFFSET] &= ~BOOT_DEBUG_RESET_MODE;
	break;

	case VBNV_TRY_B_COUNT:
	case VBNV_FW_TRY_COUNT:
	/* Clip to valid range. */
	if (value > BOOT_TRY_B_COUNT_MASK)
	value = BOOT_TRY_B_COUNT_MASK;

	raw[BOOT_OFFSET] &= ~BOOT_TRY_B_COUNT_MASK;
	raw[BOOT_OFFSET] \|= (uint8_t)value;
	break;

	case VBNV_RECOVERY_REQUEST:
	/*
	* Map values outside the valid range to the legacy reason,
	* since we can't determine if we're called from kernel or user
	* mode.
	*/
	if (value > 0xFF)
	value = VBNV_RECOVERY_LEGACY;
	raw[RECOVERY_OFFSET] = (uint8_t)value;
	break;

	case VBNV_RECOVERY_SUBCODE:
	raw[RECOVERY_SUBCODE_OFFSET] = (uint8_t)value;
	break;

	case VBNV_LOCALIZATION_INDEX:
	/* Map values outside the valid range to the default index. */
	if (value > 0xFF)
	value = 0;
	raw[LOCALIZATION_OFFSET] = (uint8_t)value;
	break;

	case VBNV_KERNEL_FIELD:
	raw[KERNEL_FIELD1_OFFSET] = (uint8_t)(value);
	raw[KERNEL_FIELD2_OFFSET] = (uint8_t)(value >> 8);
	break;

	case VBNV_DEV_BOOT_USB:
	if (value)
	raw[DEV_FLAGS_OFFSET] \|= DEV_BOOT_USB_MASK;
	else
	raw[DEV_FLAGS_OFFSET] &= ~DEV_BOOT_USB_MASK;
	break;

	case VBNV_DEV_BOOT_LEGACY:
	if (value)
	raw[DEV_FLAGS_OFFSET] \|= DEV_BOOT_LEGACY_MASK;
	else
	raw[DEV_FLAGS_OFFSET] &= ~DEV_BOOT_LEGACY_MASK;
	break;

	case VBNV_DEV_DEFAULT_BOOT:
	/* Map out of range values to boot disk */
	if (value > (DEV_DEFAULT_BOOT_MASK >>
	DEV_DEFAULT_BOOT_SHIFT))
	value = VBNV_DEV_DEFAULT_BOOT_DISK;

	raw[DEV_FLAGS_OFFSET] &= ~DEV_DEFAULT_BOOT_MASK;
	raw[DEV_FLAGS_OFFSET] \|= (uint8_t)value <<
	DEV_DEFAULT_BOOT_SHIFT;
	break;

	case VBNV_DEV_BOOT_SIGNED_ONLY:
	if (value)
	raw[DEV_FLAGS_OFFSET] \|= DEV_BOOT_SIGNED_ONLY_MASK;
	else
	raw[DEV_FLAGS_OFFSET] &= ~DEV_BOOT_SIGNED_ONLY_MASK;
	break;

	case VBNV_DEV_BOOT_FASTBOOT_FULL_CAP:
	if (value)
	raw[DEV_FLAGS_OFFSET] \|=
	DEV_BOOT_FASTBOOT_FULL_CAP_MASK;
	else
	raw[DEV_FLAGS_OFFSET] &=
	~DEV_BOOT_FASTBOOT_FULL_CAP_MASK;
	break;

	case VBNV_DISABLE_DEV_REQUEST:
	if (value)
	raw[BOOT_OFFSET] \|= BOOT_DISABLE_DEV_REQUEST;
	else
	raw[BOOT_OFFSET] &= ~BOOT_DISABLE_DEV_REQUEST;
	break;

	case VBNV_OPROM_NEEDED:
	if (value)
	raw[BOOT_OFFSET] \|= BOOT_OPROM_NEEDED;
	else
	raw[BOOT_OFFSET] &= ~BOOT_OPROM_NEEDED;
	break;

	case VBNV_CLEAR_TPM_OWNER_REQUEST:
	if (value)
	raw[TPM_FLAGS_OFFSET] \|= TPM_CLEAR_OWNER_REQUEST;
	else
	raw[TPM_FLAGS_OFFSET] &= ~TPM_CLEAR_OWNER_REQUEST;
	break;

	case VBNV_CLEAR_TPM_OWNER_DONE:
	if (value)
	raw[TPM_FLAGS_OFFSET] \|= TPM_CLEAR_OWNER_DONE;
	else
	raw[TPM_FLAGS_OFFSET] &= ~TPM_CLEAR_OWNER_DONE;
	break;

	case VBNV_TPM_REQUESTED_REBOOT:
	if (value)
	raw[TPM_FLAGS_OFFSET] \|= TPM_REBOOTED;
	else
	raw[TPM_FLAGS_OFFSET] &= ~TPM_REBOOTED;
	break;

	case VBNV_BACKUP_NVRAM_REQUEST:
	if (value)
	raw[BOOT_OFFSET] \|= BOOT_BACKUP_NVRAM;
	else
	raw[BOOT_OFFSET] &= ~BOOT_BACKUP_NVRAM;
	break;

	case VBNV_FW_TRY_NEXT:
	if (value)
	raw[BOOT2_OFFSET] \|= BOOT2_TRY_NEXT;
	else
	raw[BOOT2_OFFSET] &= ~BOOT2_TRY_NEXT;
	break;

	case VBNV_FW_TRIED:
	if (value)
	raw[BOOT2_OFFSET] \|= BOOT2_TRIED;
	else
	raw[BOOT2_OFFSET] &= ~BOOT2_TRIED;
	break;

	case VBNV_FW_RESULT:
	/* Map out of range values to unknown */
	if (value > BOOT2_RESULT_MASK)
	value = VBNV_FW_RESULT_UNKNOWN;

	raw[BOOT2_OFFSET] &= ~BOOT2_RESULT_MASK;
	raw[BOOT2_OFFSET] \|= (uint8_t)value;
	break;

	case VBNV_FW_PREV_TRIED:
	if (value)
	raw[BOOT2_OFFSET] \|= BOOT2_PREV_TRIED;
	else
	raw[BOOT2_OFFSET] &= ~BOOT2_PREV_TRIED;
	break;

	case VBNV_FW_PREV_RESULT:
	/* Map out of range values to unknown */
	if (value > BOOT2_RESULT_MASK)
	value = VBNV_FW_RESULT_UNKNOWN;

	raw[BOOT2_OFFSET] &= ~BOOT2_PREV_RESULT_MASK;
	raw[BOOT2_OFFSET] \|= (uint8_t)value << BOOT2_PREV_RESULT_SHIFT;
	break;

	case VBNV_FW_REQ_WIPEOUT:
	if (value)
	raw[HEADER_OFFSET] \|= HEADER_WIPEOUT;
	else
	raw[HEADER_OFFSET] &= ~HEADER_WIPEOUT;
	break;

	case VBNV_FASTBOOT_UNLOCK_IN_FW:
	if (value)
	raw[MISC_OFFSET] \|= MISC_UNLOCK_FASTBOOT;
	else
	raw[MISC_OFFSET] &= ~MISC_UNLOCK_FASTBOOT;
	break;

	case VBNV_BOOT_ON_AC_DETECT:
	if (value)
	raw[MISC_OFFSET] \|= MISC_BOOT_ON_AC_DETECT;
	else
	raw[MISC_OFFSET] &= ~MISC_BOOT_ON_AC_DETECT;
	break;

	case VBNV_TRY_RO_SYNC:
	if (value)
	raw[MISC_OFFSET] \|= MISC_TRY_RO_SYNC;
	else
	raw[MISC_OFFSET] &= ~MISC_TRY_RO_SYNC;
	break;

	case VBNV_BATTERY_CUTOFF_REQUEST:
	if (value)
	raw[MISC_OFFSET] \|= MISC_BATTERY_CUTOFF_REQUEST;
	else
	raw[MISC_OFFSET] &= ~MISC_BATTERY_CUTOFF_REQUEST;
	break;

	case VBNV_KERNEL_MAX_ROLLFORWARD:
	raw[KERNEL_MAX_ROLLFORWARD1_OFFSET] = (uint8_t)(value);
	raw[KERNEL_MAX_ROLLFORWARD2_OFFSET] = (uint8_t)(value >> 8);
	raw[KERNEL_MAX_ROLLFORWARD3_OFFSET] = (uint8_t)(value >> 16);
	raw[KERNEL_MAX_ROLLFORWARD4_OFFSET] = (uint8_t)(value >> 24);
	break;

	default:
	return 1;
	}

	/* Need to regenerate CRC, since the value changed. */
	context->regenerate_crc = 1;
	return 0;
	}