src/security/vboot/vboot_logic.c - mirrors/cros/chromiumos/third_party/coreboot - Git at Google

 /* SPDX-License-Identifier: GPL-2.0-only */

 #include <arch/exception.h>
 #include <assert.h>
 #include <console/console.h>
 #include <bootmode.h>
 #include <ec/google/chromeec/ec.h>
 #include <fmap.h>
 #include <security/tpm/tspi/crtm.h>
 #include <security/tpm/tss/vendor/cr50/cr50.h>
 #include <security/tpm/tss_errors.h>
 #include <security/vboot/misc.h>
 #include <security/vboot/vbnv.h>
 #include <security/vboot/tpm_common.h>
 #include <string.h>
 #include <timestamp.h>
 #include <vb2_api.h>
 #include <boot_device.h>

 #include "antirollback.h"

 /* The max hash size to expect is for SHA512. */
 #define VBOOT_MAX_HASH_SIZE VB2_SHA512_DIGEST_SIZE

 /* exports */

 vb2_error_t vb2ex_read_resource(struct vb2_context *ctx,
 				enum vb2_resource_index index,
 				uint32_t offset,
 				void *buf,
 				uint32_t size)
 {
 	struct region_device rdev;
 	const char *name;

 	switch (index) {
 	case VB2_RES_GBB:
 		name = "GBB";
 		break;
 	case VB2_RES_FW_VBLOCK:
 		if (vboot_is_firmware_slot_a(ctx))
 			name = "VBLOCK_A";
 		else
 			name = "VBLOCK_B";
 		break;
 	default:
 		return VB2_ERROR_EX_READ_RESOURCE_INDEX;
 	}

 	if (fmap_locate_area_as_rdev(name, &rdev))
 		return VB2_ERROR_EX_READ_RESOURCE_SIZE;

 	if (rdev_readat(&rdev, buf, offset, size) != size)
 		return VB2_ERROR_EX_READ_RESOURCE_SIZE;

 	return VB2_SUCCESS;
 }

 static vb2_error_t handle_digest_result(void *slot_hash, size_t slot_hash_sz)
 {
 	int is_resume;

 	/*
 	 * Chrome EC is the only support for vboot_save_hash() &
 	 * vboot_retrieve_hash(), if Chrome EC is not enabled then return.
 	 */
 	if (!CONFIG(EC_GOOGLE_CHROMEEC))
 		return VB2_SUCCESS;

 	/*
 	 * Nothing to do since resuming on the platform doesn't require
 	 * vboot verification again.
 	 */
 	if (!CONFIG(RESUME_PATH_SAME_AS_BOOT))
 		return VB2_SUCCESS;

 	/*
 	 * Assume that if vboot doesn't start in bootblock verified
 	 * RW memory init code is not employed. i.e. memory init code
 	 * lives in RO CBFS.
 	 */
 	if (!CONFIG(VBOOT_STARTS_IN_BOOTBLOCK))
 		return VB2_SUCCESS;

 	is_resume = platform_is_resuming();

 	if (is_resume > 0) {
 		uint8_t saved_hash[VBOOT_MAX_HASH_SIZE];
 		const size_t saved_hash_sz = sizeof(saved_hash);

 		assert(slot_hash_sz <= saved_hash_sz);

 		printk(BIOS_DEBUG, "Platform is resuming.\n");

 		if (vboot_retrieve_hash(saved_hash, saved_hash_sz)) {
 			printk(BIOS_ERR, "Couldn't retrieve saved hash.\n");
 			return VB2_ERROR_UNKNOWN;
 		}

 		if (memcmp(saved_hash, slot_hash, slot_hash_sz)) {
 			printk(BIOS_ERR, "Hash mismatch on resume.\n");
 			return VB2_ERROR_UNKNOWN;
 		}
 	} else if (is_resume < 0)
 		printk(BIOS_ERR, "Unable to determine if platform resuming.\n");

 	printk(BIOS_DEBUG, "Saving vboot hash.\n");

 	/* Always save the hash for the current boot. */
 	if (vboot_save_hash(slot_hash, slot_hash_sz)) {
 		printk(BIOS_ERR, "Error saving vboot hash.\n");
 		/* Though this is an error don't report it up since it could
 		 * lead to a reboot loop. The consequence of this is that
 		 * we will most likely fail resuming because of EC issues or
 		 * the hash digest not matching. */
 		return VB2_SUCCESS;
 	}

 	return VB2_SUCCESS;
 }

 static vb2_error_t hash_body(struct vb2_context *ctx,
 			     struct region_device *fw_body)
 {
 	uint64_t load_ts;
 	uint32_t remaining;
 	uint8_t block[CONFIG_VBOOT_HASH_BLOCK_SIZE];
 	uint8_t hash_digest[VBOOT_MAX_HASH_SIZE];
 	const size_t hash_digest_sz = sizeof(hash_digest);
 	size_t block_size = sizeof(block);
 	size_t offset;
 	vb2_error_t rc;

 	/* Clear the full digest so that any hash digests less than the
 	 * max have trailing zeros. */
 	memset(hash_digest, 0, hash_digest_sz);

 	/*
 	 * Since loading the firmware and calculating its hash is intertwined,
 	 * we use this little trick to measure them separately and pretend it
 	 * was first loaded and then hashed in one piece with the timestamps.
 	 * (This split won't make sense with memory-mapped media like on x86.)
 	 */
 	load_ts = timestamp_get();
 	timestamp_add(TS_HASH_BODY_START, load_ts);

 	remaining = region_device_sz(fw_body);
 	offset = 0;

 	/* Start the body hash */
 	rc = vb2api_init_hash(ctx, VB2_HASH_TAG_FW_BODY);
 	if (rc)
 		return rc;

 	/* Extend over the body */
 	while (remaining) {
 		uint64_t temp_ts;
 		if (block_size > remaining)
 			block_size = remaining;

 		temp_ts = timestamp_get();
 		if (rdev_readat(fw_body, block, offset, block_size) < 0)
 			return VB2_ERROR_UNKNOWN;
 		load_ts += timestamp_get() - temp_ts;

 		rc = vb2api_extend_hash(ctx, block, block_size);
 		if (rc)
 			return rc;

 		remaining -= block_size;
 		offset += block_size;
 	}

 	timestamp_add(TS_LOADING_END, load_ts);
 	timestamp_add_now(TS_HASHING_END);

 	/* Check the result (with RSA signature verification) */
 	rc = vb2api_check_hash_get_digest(ctx, hash_digest, hash_digest_sz);
 	if (rc)
 		return rc;

 	timestamp_add_now(TS_HASH_BODY_END);

 	return handle_digest_result(hash_digest, hash_digest_sz);
 }

 static tpm_result_t extend_pcrs(struct vb2_context *ctx)
 {
 	tpm_result_t rc;
 	rc = vboot_extend_pcr(ctx, CONFIG_PCR_BOOT_MODE, BOOT_MODE_PCR);
 	if (rc)
 		return rc;
 	return vboot_extend_pcr(ctx, CONFIG_PCR_HWID, HWID_DIGEST_PCR);
 }

 #define EC_EFS_BOOT_MODE_VERIFIED_RW	0x00
 #define EC_EFS_BOOT_MODE_UNTRUSTED_RO	0x01
 #define EC_EFS_BOOT_MODE_TRUSTED_RO	0x02

 static const char *get_boot_mode_string(uint8_t boot_mode)
 {
 	if (boot_mode == EC_EFS_BOOT_MODE_TRUSTED_RO)
 		return "TRUSTED_RO";
 	else if (boot_mode == EC_EFS_BOOT_MODE_UNTRUSTED_RO)
 		return "UNTRUSTED_RO";
 	else if (boot_mode == EC_EFS_BOOT_MODE_VERIFIED_RW)
 		return "VERIFIED_RW";
 	else
 		return "UNDEFINED";
 }

 static void check_boot_mode(struct vb2_context *ctx)
 {
 	uint8_t boot_mode;
 	tpm_result_t rc;

 	rc = tlcl_cr50_get_boot_mode(&boot_mode);
 	switch (rc) {
 	case TPM_CB_NO_SUCH_COMMAND:
 		printk(BIOS_WARNING, "GSC does not support GET_BOOT_MODE.\n");
 		/* Proceed to legacy boot model. */
 		return;
 	case TPM_SUCCESS:
 		break;
 	default:
 		printk(BIOS_ERR,
 		       "Communication error(%#x) in getting GSC boot mode.\n", rc);
 		vb2api_fail(ctx, VB2_RECOVERY_GSC_BOOT_MODE, rc);
 		return;
 	}

 	printk(BIOS_INFO, "GSC says boot_mode is %s(0x%02x).\n",
 	       get_boot_mode_string(boot_mode), boot_mode);

 	if (boot_mode == EC_EFS_BOOT_MODE_UNTRUSTED_RO)
 		ctx->flags |= VB2_CONTEXT_NO_BOOT;
 	else if (boot_mode == EC_EFS_BOOT_MODE_TRUSTED_RO)
 		ctx->flags |= VB2_CONTEXT_EC_TRUSTED;
 }

 /* Verify and select the firmware in the RW image */
 void verstage_main(void)
 {
 	struct vb2_context *ctx;
 	tpm_result_t tpm_rc;
 	vb2_error_t rv;

 	timestamp_add_now(TS_VBOOT_START);

 	/* Lockdown SPI flash controller if required */
 	if (CONFIG(BOOTMEDIA_LOCK_IN_VERSTAGE))
 		boot_device_security_lockdown();

 	/* Set up context and work buffer */
 	ctx = vboot_get_context();

 	/* Initialize and read nvdata from non-volatile storage. */
 	vbnv_init();

 	/* Set S3 resume flag if vboot should behave differently when selecting
 	 * which slot to boot.  This is only relevant to vboot if the platform
 	 * does verification of memory init and thus must ensure it resumes with
 	 * the same slot that it booted from. */
 	if (CONFIG(RESUME_PATH_SAME_AS_BOOT) &&
 		platform_is_resuming())
 		ctx->flags |= VB2_CONTEXT_S3_RESUME;

 	if (!CONFIG(VBOOT_SLOTS_RW_AB))
 		ctx->flags |= VB2_CONTEXT_SLOT_A_ONLY;

 	/* Read secdata from TPM. Initialize TPM if secdata not found. We don't
 	 * check the return value here because vb2api_fw_phase1 will catch
 	 * invalid secdata and tell us what to do (=reboot). */
 	timestamp_add_now(TS_TPMINIT_START);
 	rv = vboot_setup_tpm(ctx);
 	if (rv == TPM_SUCCESS) {
 		antirollback_read_space_firmware(ctx);
 		antirollback_read_space_kernel(ctx);
 	} else {
 		vb2api_fail(ctx, VB2_RECOVERY_RO_TPM_S_ERROR, rv);
 		if (CONFIG(TPM_SETUP_HIBERNATE_ON_ERR) &&
 				rv == TPM_CB_COMMUNICATION_ERROR) {
 			printk(BIOS_ERR, "Failed to communicate with TPM\n"
 					"Next reboot will hibernate to reset TPM");
 			/* Command the EC to hibernate on next AP shutdown */
 			if (google_chromeec_reboot(
 					EC_REBOOT_HIBERNATE,
 					EC_REBOOT_FLAG_ON_AP_SHUTDOWN)) {
 				printk(BIOS_ERR, "Failed to get EC to schedule hibernate");
 			}
 		}
 	}
 	timestamp_add_now(TS_TPMINIT_END);

 	if (get_recovery_mode_switch()) {
 		ctx->flags |= VB2_CONTEXT_FORCE_RECOVERY_MODE;
 		if (CONFIG(VBOOT_DISABLE_DEV_ON_RECOVERY))
 			ctx->flags |= VB2_CONTEXT_DISABLE_DEVELOPER_MODE;
 	}

 	if (CONFIG(VBOOT_WIPEOUT_SUPPORTED) &&
 		get_wipeout_mode_switch())
 		ctx->flags |= VB2_CONTEXT_FORCE_WIPEOUT_MODE;

 	if (CONFIG(VBOOT_LID_SWITCH) && !get_lid_switch())
 		ctx->flags |= VB2_CONTEXT_NOFAIL_BOOT;

 	/* Mainboard/SoC always initializes display. */
 	if (!CONFIG(VBOOT_MUST_REQUEST_DISPLAY) || CONFIG(VBOOT_ALWAYS_ENABLE_DISPLAY))
 		ctx->flags |= VB2_CONTEXT_DISPLAY_INIT;

 	/*
 	 * Get boot mode from GSC. This allows us to refuse to boot OS
 	 * (with VB2_CONTEXT_NO_BOOT) or to switch to developer mode (with
 	 * !VB2_CONTEXT_EC_TRUSTED).
 	 *
 	 * If there is an communication error, a recovery reason will be set and
 	 * vb2api_fw_phase1 will route us to recovery mode.
 	 */
 	if (CONFIG(TPM_GOOGLE))
 		check_boot_mode(ctx);

 	if (get_ec_is_trusted())
 		ctx->flags |= VB2_CONTEXT_EC_TRUSTED;

 	/* Do early init (set up secdata and NVRAM, load GBB) */
 	printk(BIOS_INFO, "Phase 1\n");
 	rv = vb2api_fw_phase1(ctx);

 	if (rv) {
 		/*
 		 * If vb2api_fw_phase1 fails, check for return value.
 		 * If it is set to VB2_ERROR_API_PHASE1_RECOVERY, then continue
 		 * into recovery mode.
 		 * For any other error code, save context if needed and reboot.
 		 */
 		if (rv == VB2_ERROR_API_PHASE1_RECOVERY) {
 			printk(BIOS_INFO, "Recovery requested (%#x)\n", rv);
 			vboot_save_data(ctx);
 			extend_pcrs(ctx); /* ignore failures */
 			goto verstage_main_exit;
 		}
 		vboot_save_and_reboot(ctx, rv);
 	}

 	/* Determine which firmware slot to boot (based on NVRAM) */
 	printk(BIOS_INFO, "Phase 2\n");
 	rv = vb2api_fw_phase2(ctx);
 	if (rv)
 		vboot_save_and_reboot(ctx, rv);

 	/* Try that slot (verify its keyblock and preamble) */
 	printk(BIOS_INFO, "Phase 3\n");
 	timestamp_add_now(TS_VERIFY_SLOT_START);
 	rv = vb2api_fw_phase3(ctx);
 	timestamp_add_now(TS_VERIFY_SLOT_END);
 	if (rv)
 		vboot_save_and_reboot(ctx, rv);

 	printk(BIOS_INFO, "Phase 4\n");
 	if (CONFIG(VBOOT_CBFS_INTEGRATION)) {
 		struct vb2_hash *metadata_hash;
 		rv = vb2api_get_metadata_hash(ctx, &metadata_hash);
 		if (rv == VB2_SUCCESS)
 			rv = handle_digest_result(metadata_hash->raw,
 						  vb2_digest_size(metadata_hash->algo));
 	} else {
 		struct region_device fw_body;
 		if (vboot_locate_firmware(ctx, &fw_body))
 			die_with_post_code(POSTCODE_INVALID_ROM,
 					   "Failed to read FMAP to locate firmware");

 		rv = hash_body(ctx, &fw_body);
 	}

 	if (rv)
 		vboot_save_and_reboot(ctx, rv);
 	vboot_save_data(ctx);

 	/* Only extend PCRs once on boot. */
 	if (!(ctx->flags & VB2_CONTEXT_S3_RESUME)) {
 		timestamp_add_now(TS_TPMPCR_START);
 		tpm_rc = extend_pcrs(ctx);
 		if (tpm_rc) {
 			printk(BIOS_WARNING, "Failed to extend TPM PCRs (%#x)\n",
 				tpm_rc);
 			vboot_fail_and_reboot(ctx,
 				VB2_RECOVERY_RO_TPM_U_ERROR,
 				tpm_rc);
 		}
 		timestamp_add_now(TS_TPMPCR_END);
 	}

 	/* Lock TPM */

 	timestamp_add_now(TS_TPMLOCK_START);
 	tpm_rc = antirollback_lock_space_firmware();
 	if (tpm_rc) {
 		printk(BIOS_INFO, "Failed to lock TPM (%#x)\n", tpm_rc);
 		vboot_fail_and_reboot(ctx, VB2_RECOVERY_RO_TPM_L_ERROR, 0);
 	}
 	timestamp_add_now(TS_TPMLOCK_END);

 	/* Lock rec hash space if available. */
 	if (CONFIG(VBOOT_HAS_REC_HASH_SPACE)) {
 		tpm_rc = antirollback_lock_space_mrc_hash(
 				MRC_REC_HASH_NV_INDEX);
 		if (tpm_rc) {
 			printk(BIOS_INFO, "Failed to lock rec hash space(%#x)\n",
 				tpm_rc);
 			vboot_fail_and_reboot(ctx, VB2_RECOVERY_RO_TPM_REC_HASH_L_ERROR, tpm_rc);
 		}
 	}

 	printk(BIOS_INFO, "Slot %c is selected\n",
 	       vboot_is_firmware_slot_a(ctx) ? 'A' : 'B');

  verstage_main_exit:
 	timestamp_add_now(TS_VBOOT_END);
 }
	/* SPDX-License-Identifier: GPL-2.0-only */

	#include <arch/exception.h>
	#include <assert.h>
	#include <console/console.h>
	#include <bootmode.h>
	#include <ec/google/chromeec/ec.h>
	#include <fmap.h>
	#include <security/tpm/tspi/crtm.h>
	#include <security/tpm/tss/vendor/cr50/cr50.h>
	#include <security/tpm/tss_errors.h>
	#include <security/vboot/misc.h>
	#include <security/vboot/vbnv.h>
	#include <security/vboot/tpm_common.h>
	#include <string.h>
	#include <timestamp.h>
	#include <vb2_api.h>
	#include <boot_device.h>

	#include "antirollback.h"

	/* The max hash size to expect is for SHA512. */
	#define VBOOT_MAX_HASH_SIZE VB2_SHA512_DIGEST_SIZE

	/* exports */

	vb2_error_t vb2ex_read_resource(struct vb2_context *ctx,
	enum vb2_resource_index index,
	uint32_t offset,
	void *buf,
	uint32_t size)
	{
	struct region_device rdev;
	const char *name;

	switch (index) {
	case VB2_RES_GBB:
	name = "GBB";
	break;
	case VB2_RES_FW_VBLOCK:
	if (vboot_is_firmware_slot_a(ctx))
	name = "VBLOCK_A";
	else
	name = "VBLOCK_B";
	break;
	default:
	return VB2_ERROR_EX_READ_RESOURCE_INDEX;
	}

	if (fmap_locate_area_as_rdev(name, &rdev))
	return VB2_ERROR_EX_READ_RESOURCE_SIZE;

	if (rdev_readat(&rdev, buf, offset, size) != size)
	return VB2_ERROR_EX_READ_RESOURCE_SIZE;

	return VB2_SUCCESS;
	}

	static vb2_error_t handle_digest_result(void *slot_hash, size_t slot_hash_sz)
	{
	int is_resume;

	/*
	* Chrome EC is the only support for vboot_save_hash() &
	* vboot_retrieve_hash(), if Chrome EC is not enabled then return.
	*/
	if (!CONFIG(EC_GOOGLE_CHROMEEC))
	return VB2_SUCCESS;

	/*
	* Nothing to do since resuming on the platform doesn't require
	* vboot verification again.
	*/
	if (!CONFIG(RESUME_PATH_SAME_AS_BOOT))
	return VB2_SUCCESS;

	/*
	* Assume that if vboot doesn't start in bootblock verified
	* RW memory init code is not employed. i.e. memory init code
	* lives in RO CBFS.
	*/
	if (!CONFIG(VBOOT_STARTS_IN_BOOTBLOCK))
	return VB2_SUCCESS;

	is_resume = platform_is_resuming();

	if (is_resume > 0) {
	uint8_t saved_hash[VBOOT_MAX_HASH_SIZE];
	const size_t saved_hash_sz = sizeof(saved_hash);

	assert(slot_hash_sz <= saved_hash_sz);

	printk(BIOS_DEBUG, "Platform is resuming.\n");

	if (vboot_retrieve_hash(saved_hash, saved_hash_sz)) {
	printk(BIOS_ERR, "Couldn't retrieve saved hash.\n");
	return VB2_ERROR_UNKNOWN;
	}

	if (memcmp(saved_hash, slot_hash, slot_hash_sz)) {
	printk(BIOS_ERR, "Hash mismatch on resume.\n");
	return VB2_ERROR_UNKNOWN;
	}
	} else if (is_resume < 0)
	printk(BIOS_ERR, "Unable to determine if platform resuming.\n");

	printk(BIOS_DEBUG, "Saving vboot hash.\n");

	/* Always save the hash for the current boot. */
	if (vboot_save_hash(slot_hash, slot_hash_sz)) {
	printk(BIOS_ERR, "Error saving vboot hash.\n");
	/* Though this is an error don't report it up since it could
	* lead to a reboot loop. The consequence of this is that
	* we will most likely fail resuming because of EC issues or
	* the hash digest not matching. */
	return VB2_SUCCESS;
	}

	return VB2_SUCCESS;
	}

	static vb2_error_t hash_body(struct vb2_context *ctx,
	struct region_device *fw_body)
	{
	uint64_t load_ts;
	uint32_t remaining;
	uint8_t block[CONFIG_VBOOT_HASH_BLOCK_SIZE];
	uint8_t hash_digest[VBOOT_MAX_HASH_SIZE];
	const size_t hash_digest_sz = sizeof(hash_digest);
	size_t block_size = sizeof(block);
	size_t offset;
	vb2_error_t rc;

	/* Clear the full digest so that any hash digests less than the
	* max have trailing zeros. */
	memset(hash_digest, 0, hash_digest_sz);

	/*
	* Since loading the firmware and calculating its hash is intertwined,
	* we use this little trick to measure them separately and pretend it
	* was first loaded and then hashed in one piece with the timestamps.
	* (This split won't make sense with memory-mapped media like on x86.)
	*/
	load_ts = timestamp_get();
	timestamp_add(TS_HASH_BODY_START, load_ts);

	remaining = region_device_sz(fw_body);
	offset = 0;

	/* Start the body hash */
	rc = vb2api_init_hash(ctx, VB2_HASH_TAG_FW_BODY);
	if (rc)
	return rc;

	/* Extend over the body */
	while (remaining) {
	uint64_t temp_ts;
	if (block_size > remaining)
	block_size = remaining;

	temp_ts = timestamp_get();
	if (rdev_readat(fw_body, block, offset, block_size) < 0)
	return VB2_ERROR_UNKNOWN;
	load_ts += timestamp_get() - temp_ts;

	rc = vb2api_extend_hash(ctx, block, block_size);
	if (rc)
	return rc;

	remaining -= block_size;
	offset += block_size;
	}

	timestamp_add(TS_LOADING_END, load_ts);
	timestamp_add_now(TS_HASHING_END);

	/* Check the result (with RSA signature verification) */
	rc = vb2api_check_hash_get_digest(ctx, hash_digest, hash_digest_sz);
	if (rc)
	return rc;

	timestamp_add_now(TS_HASH_BODY_END);

	return handle_digest_result(hash_digest, hash_digest_sz);
	}

	static tpm_result_t extend_pcrs(struct vb2_context *ctx)
	{
	tpm_result_t rc;
	rc = vboot_extend_pcr(ctx, CONFIG_PCR_BOOT_MODE, BOOT_MODE_PCR);
	if (rc)
	return rc;
	return vboot_extend_pcr(ctx, CONFIG_PCR_HWID, HWID_DIGEST_PCR);
	}

	#define EC_EFS_BOOT_MODE_VERIFIED_RW 0x00
	#define EC_EFS_BOOT_MODE_UNTRUSTED_RO 0x01
	#define EC_EFS_BOOT_MODE_TRUSTED_RO 0x02

	static const char *get_boot_mode_string(uint8_t boot_mode)
	{
	if (boot_mode == EC_EFS_BOOT_MODE_TRUSTED_RO)
	return "TRUSTED_RO";
	else if (boot_mode == EC_EFS_BOOT_MODE_UNTRUSTED_RO)
	return "UNTRUSTED_RO";
	else if (boot_mode == EC_EFS_BOOT_MODE_VERIFIED_RW)
	return "VERIFIED_RW";
	else
	return "UNDEFINED";
	}

	static void check_boot_mode(struct vb2_context *ctx)
	{
	uint8_t boot_mode;
	tpm_result_t rc;

	rc = tlcl_cr50_get_boot_mode(&boot_mode);
	switch (rc) {
	case TPM_CB_NO_SUCH_COMMAND:
	printk(BIOS_WARNING, "GSC does not support GET_BOOT_MODE.\n");
	/* Proceed to legacy boot model. */
	return;
	case TPM_SUCCESS:
	break;
	default:
	printk(BIOS_ERR,
	"Communication error(%#x) in getting GSC boot mode.\n", rc);
	vb2api_fail(ctx, VB2_RECOVERY_GSC_BOOT_MODE, rc);
	return;
	}

	printk(BIOS_INFO, "GSC says boot_mode is %s(0x%02x).\n",
	get_boot_mode_string(boot_mode), boot_mode);

	if (boot_mode == EC_EFS_BOOT_MODE_UNTRUSTED_RO)
	ctx->flags \|= VB2_CONTEXT_NO_BOOT;
	else if (boot_mode == EC_EFS_BOOT_MODE_TRUSTED_RO)
	ctx->flags \|= VB2_CONTEXT_EC_TRUSTED;
	}

	/* Verify and select the firmware in the RW image */
	void verstage_main(void)
	{
	struct vb2_context *ctx;
	tpm_result_t tpm_rc;
	vb2_error_t rv;

	timestamp_add_now(TS_VBOOT_START);

	/* Lockdown SPI flash controller if required */
	if (CONFIG(BOOTMEDIA_LOCK_IN_VERSTAGE))
	boot_device_security_lockdown();

	/* Set up context and work buffer */
	ctx = vboot_get_context();

	/* Initialize and read nvdata from non-volatile storage. */
	vbnv_init();

	/* Set S3 resume flag if vboot should behave differently when selecting
	* which slot to boot. This is only relevant to vboot if the platform
	* does verification of memory init and thus must ensure it resumes with
	* the same slot that it booted from. */
	if (CONFIG(RESUME_PATH_SAME_AS_BOOT) &&
	platform_is_resuming())
	ctx->flags \|= VB2_CONTEXT_S3_RESUME;

	if (!CONFIG(VBOOT_SLOTS_RW_AB))
	ctx->flags \|= VB2_CONTEXT_SLOT_A_ONLY;

	/* Read secdata from TPM. Initialize TPM if secdata not found. We don't
	* check the return value here because vb2api_fw_phase1 will catch
	* invalid secdata and tell us what to do (=reboot). */
	timestamp_add_now(TS_TPMINIT_START);
	rv = vboot_setup_tpm(ctx);
	if (rv == TPM_SUCCESS) {
	antirollback_read_space_firmware(ctx);
	antirollback_read_space_kernel(ctx);
	} else {
	vb2api_fail(ctx, VB2_RECOVERY_RO_TPM_S_ERROR, rv);
	if (CONFIG(TPM_SETUP_HIBERNATE_ON_ERR) &&
	rv == TPM_CB_COMMUNICATION_ERROR) {
	printk(BIOS_ERR, "Failed to communicate with TPM\n"
	"Next reboot will hibernate to reset TPM");
	/* Command the EC to hibernate on next AP shutdown */
	if (google_chromeec_reboot(
	EC_REBOOT_HIBERNATE,
	EC_REBOOT_FLAG_ON_AP_SHUTDOWN)) {
	printk(BIOS_ERR, "Failed to get EC to schedule hibernate");
	}
	}
	}
	timestamp_add_now(TS_TPMINIT_END);

	if (get_recovery_mode_switch()) {
	ctx->flags \|= VB2_CONTEXT_FORCE_RECOVERY_MODE;
	if (CONFIG(VBOOT_DISABLE_DEV_ON_RECOVERY))
	ctx->flags \|= VB2_CONTEXT_DISABLE_DEVELOPER_MODE;
	}

	if (CONFIG(VBOOT_WIPEOUT_SUPPORTED) &&
	get_wipeout_mode_switch())
	ctx->flags \|= VB2_CONTEXT_FORCE_WIPEOUT_MODE;

	if (CONFIG(VBOOT_LID_SWITCH) && !get_lid_switch())
	ctx->flags \|= VB2_CONTEXT_NOFAIL_BOOT;

	/* Mainboard/SoC always initializes display. */
	if (!CONFIG(VBOOT_MUST_REQUEST_DISPLAY) \|\| CONFIG(VBOOT_ALWAYS_ENABLE_DISPLAY))
	ctx->flags \|= VB2_CONTEXT_DISPLAY_INIT;

	/*
	* Get boot mode from GSC. This allows us to refuse to boot OS
	* (with VB2_CONTEXT_NO_BOOT) or to switch to developer mode (with
	* !VB2_CONTEXT_EC_TRUSTED).
	*
	* If there is an communication error, a recovery reason will be set and
	* vb2api_fw_phase1 will route us to recovery mode.
	*/
	if (CONFIG(TPM_GOOGLE))
	check_boot_mode(ctx);

	if (get_ec_is_trusted())
	ctx->flags \|= VB2_CONTEXT_EC_TRUSTED;

	/* Do early init (set up secdata and NVRAM, load GBB) */
	printk(BIOS_INFO, "Phase 1\n");
	rv = vb2api_fw_phase1(ctx);

	if (rv) {
	/*
	* If vb2api_fw_phase1 fails, check for return value.
	* If it is set to VB2_ERROR_API_PHASE1_RECOVERY, then continue
	* into recovery mode.
	* For any other error code, save context if needed and reboot.
	*/
	if (rv == VB2_ERROR_API_PHASE1_RECOVERY) {
	printk(BIOS_INFO, "Recovery requested (%#x)\n", rv);
	vboot_save_data(ctx);
	extend_pcrs(ctx); /* ignore failures */
	goto verstage_main_exit;
	}
	vboot_save_and_reboot(ctx, rv);
	}

	/* Determine which firmware slot to boot (based on NVRAM) */
	printk(BIOS_INFO, "Phase 2\n");
	rv = vb2api_fw_phase2(ctx);
	if (rv)
	vboot_save_and_reboot(ctx, rv);

	/* Try that slot (verify its keyblock and preamble) */
	printk(BIOS_INFO, "Phase 3\n");
	timestamp_add_now(TS_VERIFY_SLOT_START);
	rv = vb2api_fw_phase3(ctx);
	timestamp_add_now(TS_VERIFY_SLOT_END);
	if (rv)
	vboot_save_and_reboot(ctx, rv);

	printk(BIOS_INFO, "Phase 4\n");
	if (CONFIG(VBOOT_CBFS_INTEGRATION)) {
	struct vb2_hash *metadata_hash;
	rv = vb2api_get_metadata_hash(ctx, &metadata_hash);
	if (rv == VB2_SUCCESS)
	rv = handle_digest_result(metadata_hash->raw,
	vb2_digest_size(metadata_hash->algo));
	} else {
	struct region_device fw_body;
	if (vboot_locate_firmware(ctx, &fw_body))
	die_with_post_code(POSTCODE_INVALID_ROM,
	"Failed to read FMAP to locate firmware");

	rv = hash_body(ctx, &fw_body);
	}

	if (rv)
	vboot_save_and_reboot(ctx, rv);
	vboot_save_data(ctx);

	/* Only extend PCRs once on boot. */
	if (!(ctx->flags & VB2_CONTEXT_S3_RESUME)) {
	timestamp_add_now(TS_TPMPCR_START);
	tpm_rc = extend_pcrs(ctx);
	if (tpm_rc) {
	printk(BIOS_WARNING, "Failed to extend TPM PCRs (%#x)\n",
	tpm_rc);
	vboot_fail_and_reboot(ctx,
	VB2_RECOVERY_RO_TPM_U_ERROR,
	tpm_rc);
	}
	timestamp_add_now(TS_TPMPCR_END);
	}

	/* Lock TPM */

	timestamp_add_now(TS_TPMLOCK_START);
	tpm_rc = antirollback_lock_space_firmware();
	if (tpm_rc) {
	printk(BIOS_INFO, "Failed to lock TPM (%#x)\n", tpm_rc);
	vboot_fail_and_reboot(ctx, VB2_RECOVERY_RO_TPM_L_ERROR, 0);
	}
	timestamp_add_now(TS_TPMLOCK_END);

	/* Lock rec hash space if available. */
	if (CONFIG(VBOOT_HAS_REC_HASH_SPACE)) {
	tpm_rc = antirollback_lock_space_mrc_hash(
	MRC_REC_HASH_NV_INDEX);
	if (tpm_rc) {
	printk(BIOS_INFO, "Failed to lock rec hash space(%#x)\n",
	tpm_rc);
	vboot_fail_and_reboot(ctx, VB2_RECOVERY_RO_TPM_REC_HASH_L_ERROR, tpm_rc);
	}
	}

	printk(BIOS_INFO, "Slot %c is selected\n",
	vboot_is_firmware_slot_a(ctx) ? 'A' : 'B');

	verstage_main_exit:
	timestamp_add_now(TS_VBOOT_END);
	}