src/security/vboot/vboot_logic.c - coreboot - Gitiles

 /*
  * This file is part of the coreboot project.
  *
  * Copyright 2014 Google Inc.
  *
  * 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 <arch/exception.h>
 #include <assert.h>
 #include <bootmode.h>
 #include <cbmem.h>
 #include <console/console.h>
 #include <console/vtxprintf.h>
 #include <fmap.h>
 #include <string.h>
 #include <timestamp.h>
 #include <vb2_api.h>
 #include <security/vboot/misc.h>
 #include <security/vboot/vbnv.h>
 #include <security/vboot/vboot_crtm.h>
 #include <security/vboot/tpm_common.h>

 #include "antirollback.h"

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

 #define TODO_BLOCK_SIZE 1024

 /* exports */

 void vb2ex_printf(const char *func, const char *fmt, ...)
 {
 	va_list args;

 	if (func)
 		printk(BIOS_INFO, "VB2:%s() ", func);

 	va_start(args, fmt);
 	vprintk(BIOS_INFO, fmt, args);
 	va_end(args);

 	return;
 }

 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;
 }

 void vb2ex_abort(void)
 {
 	die("vboot has aborted execution; exit\n");
 }

 /* No-op stubs that can be overridden by SoCs with hardware crypto support. */
 __weak vb2_error_t vb2ex_hwcrypto_digest_init(enum vb2_hash_algorithm hash_alg,
 					      uint32_t data_size)
 {
 	return VB2_ERROR_EX_HWCRYPTO_UNSUPPORTED;
 }

 __weak vb2_error_t vb2ex_hwcrypto_digest_extend(const uint8_t *buf,
 						uint32_t size)
 {
 	BUG(); /* Should never get called if init() returned an error. */
 	return VB2_ERROR_UNKNOWN;
 }

 __weak vb2_error_t vb2ex_hwcrypto_digest_finalize(uint8_t *digest,
 						  uint32_t digest_size)
 {
 	BUG(); /* Should never get called if init() returned an error. */
 	return VB2_ERROR_UNKNOWN;
 }

 static int 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 0;

 	/*
 	 * Nothing to do since resuming on the platform doesn't require
 	 * vboot verification again.
 	 */
 	if (!CONFIG(RESUME_PATH_SAME_AS_BOOT))
 		return 0;

 	/*
 	 * 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 0;

 	is_resume = vboot_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 -1;
 		}

 		if (memcmp(saved_hash, slot_hash, slot_hash_sz)) {
 			printk(BIOS_ERR, "Hash mismatch on resume.\n");
 			return -1;
 		}
 	} 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 0;
 	}

 	return 0;
 }

 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[TODO_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 rv;

 	/* 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_START_HASH_BODY, load_ts);

 	remaining = region_device_sz(fw_body);
 	offset = 0;

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

 	/* 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;

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

 		remaining -= block_size;
 		offset += block_size;
 	}

 	timestamp_add(TS_DONE_LOADING, load_ts);
 	timestamp_add_now(TS_DONE_HASHING);

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

 	timestamp_add_now(TS_END_HASH_BODY);

 	if (handle_digest_result(hash_digest, hash_digest_sz))
 		return VB2_ERROR_UNKNOWN;

 	return VB2_SUCCESS;
 }

 void vboot_save_nvdata_only(struct vb2_context *ctx)
 {
 	assert(!(ctx->flags & (VB2_CONTEXT_SECDATA_FIRMWARE_CHANGED |
 			       VB2_CONTEXT_SECDATA_KERNEL_CHANGED)));

 	if (ctx->flags & VB2_CONTEXT_NVDATA_CHANGED) {
 		printk(BIOS_INFO, "Saving nvdata\n");
 		save_vbnv(ctx->nvdata);
 		ctx->flags &= ~VB2_CONTEXT_NVDATA_CHANGED;
 	}
 }

 void vboot_save_data(struct vb2_context *ctx)
 {
 	if (ctx->flags & VB2_CONTEXT_SECDATA_FIRMWARE_CHANGED) {
 		printk(BIOS_INFO, "Saving secdata\n");
 		antirollback_write_space_firmware(ctx);
 		ctx->flags &= ~VB2_CONTEXT_SECDATA_FIRMWARE_CHANGED;
 	}

 	vboot_save_nvdata_only(ctx);
 }

 static uint32_t extend_pcrs(struct vb2_context *ctx)
 {
 	return vboot_extend_pcr(ctx, 0, BOOT_MODE_PCR) ||
 		   vboot_extend_pcr(ctx, 1, HWID_DIGEST_PCR);
 }

 static void vboot_log_and_clear_recovery_mode_switch(int unused)
 {
 	/* Log the recovery mode switches if required, before clearing them. */
 	log_recovery_mode_switch();

 	/*
 	 * The recovery mode switch is cleared (typically backed by EC) here
 	 * to allow multiple queries to get_recovery_mode_switch() and have
 	 * them return consistent results during the verified boot path as well
 	 * as dram initialization. x86 systems ignore the saved dram settings
 	 * in the recovery path in order to start from a clean slate. Therefore
 	 * clear the state here since this function is called when memory
 	 * is known to be up.
 	 */
 	clear_recovery_mode_switch();
 }
 #if !CONFIG(VBOOT_STARTS_IN_ROMSTAGE)
 ROMSTAGE_CBMEM_INIT_HOOK(vboot_log_and_clear_recovery_mode_switch)
 #endif

 /**
  * Verify and select the firmware in the RW image
  *
  * TODO: Avoid loading a stage twice (once in hash_body & again in load_stage).
  * when per-stage verification is ready.
  */
 void verstage_main(void)
 {
 	struct vb2_context *ctx;
 	struct region_device fw_body;
 	vb2_error_t rv;

 	timestamp_add_now(TS_START_VBOOT);

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

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

 	/* 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) &&
 		vboot_platform_is_resuming())
 		ctx->flags |= VB2_CONTEXT_S3_RESUME;

 	/* 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_START_TPMINIT);
 	if (vboot_setup_tpm(ctx) == TPM_SUCCESS)
 		antirollback_read_space_firmware(ctx);
 	timestamp_add_now(TS_END_TPMINIT);

 	/* Enable measured boot mode */
 	if (CONFIG(VBOOT_MEASURED_BOOT) &&
 		!(ctx->flags & VB2_CONTEXT_S3_RESUME)) {
 		if (vboot_init_crtm() != VB2_SUCCESS)
 			die_with_post_code(POST_INVALID_ROM,
 				"Initializing measured boot mode failed!");
 	}

 	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;

 	/* 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;
 		}

 		printk(BIOS_INFO, "Reboot requested (%x)\n", rv);
 		vboot_save_data(ctx);
 		vboot_reboot();
 	}

 	/* Determine which firmware slot to boot (based on NVRAM) */
 	printk(BIOS_INFO, "Phase 2\n");
 	rv = vb2api_fw_phase2(ctx);
 	if (rv) {
 		printk(BIOS_INFO, "Reboot requested (%x)\n", rv);
 		vboot_save_data(ctx);
 		vboot_reboot();
 	}

 	/* Try that slot (verify its keyblock and preamble) */
 	printk(BIOS_INFO, "Phase 3\n");
 	timestamp_add_now(TS_START_VERIFY_SLOT);
 	rv = vb2api_fw_phase3(ctx);
 	timestamp_add_now(TS_END_VERIFY_SLOT);
 	if (rv) {
 		printk(BIOS_INFO, "Reboot requested (%x)\n", rv);
 		vboot_save_data(ctx);
 		vboot_reboot();
 	}

 	printk(BIOS_INFO, "Phase 4\n");
 	rv = vboot_locate_firmware(ctx, &fw_body);
 	if (rv)
 		die_with_post_code(POST_INVALID_ROM,
 			"Failed to read FMAP to locate firmware");

 	rv = hash_body(ctx, &fw_body);
 	vboot_save_data(ctx);
 	if (rv) {
 		printk(BIOS_INFO, "Reboot requested (%x)\n", rv);
 		vboot_reboot();
 	}

 	/* Only extend PCRs once on boot. */
 	if (!(ctx->flags & VB2_CONTEXT_S3_RESUME)) {
 		timestamp_add_now(TS_START_TPMPCR);
 		rv = extend_pcrs(ctx);
 		if (rv) {
 			printk(BIOS_WARNING,
 			       "Failed to extend TPM PCRs (%#x)\n", rv);
 			vb2api_fail(ctx, VB2_RECOVERY_RO_TPM_U_ERROR, rv);
 			vboot_save_data(ctx);
 			vboot_reboot();
 		}
 		timestamp_add_now(TS_END_TPMPCR);
 	}

 	/* Lock TPM */

 	timestamp_add_now(TS_START_TPMLOCK);
 	rv = antirollback_lock_space_firmware();
 	if (rv) {
 		printk(BIOS_INFO, "Failed to lock TPM (%x)\n", rv);
 		vb2api_fail(ctx, VB2_RECOVERY_RO_TPM_L_ERROR, 0);
 		vboot_save_data(ctx);
 		vboot_reboot();
 	}
 	timestamp_add_now(TS_END_TPMLOCK);

 	/* Lock rec hash space if available. */
 	if (CONFIG(VBOOT_HAS_REC_HASH_SPACE)) {
 		rv = antirollback_lock_space_rec_hash();
 		if (rv) {
 			printk(BIOS_INFO, "Failed to lock rec hash space(%x)\n",
 			       rv);
 			vb2api_fail(ctx, VB2_RECOVERY_RO_TPM_REC_HASH_L_ERROR,
 				    0);
 			vboot_save_data(ctx);
 			vboot_reboot();
 		}
 	}

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

  verstage_main_exit:
 	/* If CBMEM is not up yet, let the ROMSTAGE_CBMEM_INIT_HOOK take care
 	   of running this function. */
 	if (ENV_ROMSTAGE && CONFIG(VBOOT_STARTS_IN_ROMSTAGE))
 		vboot_log_and_clear_recovery_mode_switch(0);

 	/* Save recovery reason in case of unexpected reboots on x86. */
 	vboot_save_recovery_reason_vbnv();

 	timestamp_add_now(TS_END_VBOOT);
 }
	/*
	* This file is part of the coreboot project.
	*
	* Copyright 2014 Google Inc.
	*
	* 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 <arch/exception.h>
	#include <assert.h>
	#include <bootmode.h>
	#include <cbmem.h>
	#include <console/console.h>
	#include <console/vtxprintf.h>
	#include <fmap.h>
	#include <string.h>
	#include <timestamp.h>
	#include <vb2_api.h>
	#include <security/vboot/misc.h>
	#include <security/vboot/vbnv.h>
	#include <security/vboot/vboot_crtm.h>
	#include <security/vboot/tpm_common.h>

	#include "antirollback.h"

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

	#define TODO_BLOCK_SIZE 1024

	/* exports */

	void vb2ex_printf(const char func, const char fmt, ...)
	{
	va_list args;

	if (func)
	printk(BIOS_INFO, "VB2:%s() ", func);

	va_start(args, fmt);
	vprintk(BIOS_INFO, fmt, args);
	va_end(args);

	return;
	}

	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;
	}

	void vb2ex_abort(void)
	{
	die("vboot has aborted execution; exit\n");
	}

	/* No-op stubs that can be overridden by SoCs with hardware crypto support. */
	__weak vb2_error_t vb2ex_hwcrypto_digest_init(enum vb2_hash_algorithm hash_alg,
	uint32_t data_size)
	{
	return VB2_ERROR_EX_HWCRYPTO_UNSUPPORTED;
	}

	__weak vb2_error_t vb2ex_hwcrypto_digest_extend(const uint8_t *buf,
	uint32_t size)
	{
	BUG(); /* Should never get called if init() returned an error. */
	return VB2_ERROR_UNKNOWN;
	}

	__weak vb2_error_t vb2ex_hwcrypto_digest_finalize(uint8_t *digest,
	uint32_t digest_size)
	{
	BUG(); /* Should never get called if init() returned an error. */
	return VB2_ERROR_UNKNOWN;
	}

	static int 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 0;

	/*
	* Nothing to do since resuming on the platform doesn't require
	* vboot verification again.
	*/
	if (!CONFIG(RESUME_PATH_SAME_AS_BOOT))
	return 0;

	/*
	* 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 0;

	is_resume = vboot_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 -1;
	}

	if (memcmp(saved_hash, slot_hash, slot_hash_sz)) {
	printk(BIOS_ERR, "Hash mismatch on resume.\n");
	return -1;
	}
	} 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 0;
	}

	return 0;
	}

	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[TODO_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 rv;

	/* 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_START_HASH_BODY, load_ts);

	remaining = region_device_sz(fw_body);
	offset = 0;

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

	/* 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;

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

	remaining -= block_size;
	offset += block_size;
	}

	timestamp_add(TS_DONE_LOADING, load_ts);
	timestamp_add_now(TS_DONE_HASHING);

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

	timestamp_add_now(TS_END_HASH_BODY);

	if (handle_digest_result(hash_digest, hash_digest_sz))
	return VB2_ERROR_UNKNOWN;

	return VB2_SUCCESS;
	}

	void vboot_save_nvdata_only(struct vb2_context *ctx)
	{
	assert(!(ctx->flags & (VB2_CONTEXT_SECDATA_FIRMWARE_CHANGED \|
	VB2_CONTEXT_SECDATA_KERNEL_CHANGED)));

	if (ctx->flags & VB2_CONTEXT_NVDATA_CHANGED) {
	printk(BIOS_INFO, "Saving nvdata\n");
	save_vbnv(ctx->nvdata);
	ctx->flags &= ~VB2_CONTEXT_NVDATA_CHANGED;
	}
	}

	void vboot_save_data(struct vb2_context *ctx)
	{
	if (ctx->flags & VB2_CONTEXT_SECDATA_FIRMWARE_CHANGED) {
	printk(BIOS_INFO, "Saving secdata\n");
	antirollback_write_space_firmware(ctx);
	ctx->flags &= ~VB2_CONTEXT_SECDATA_FIRMWARE_CHANGED;
	}

	vboot_save_nvdata_only(ctx);
	}

	static uint32_t extend_pcrs(struct vb2_context *ctx)
	{
	return vboot_extend_pcr(ctx, 0, BOOT_MODE_PCR) \|\|
	vboot_extend_pcr(ctx, 1, HWID_DIGEST_PCR);
	}

	static void vboot_log_and_clear_recovery_mode_switch(int unused)
	{
	/* Log the recovery mode switches if required, before clearing them. */
	log_recovery_mode_switch();

	/*
	* The recovery mode switch is cleared (typically backed by EC) here
	* to allow multiple queries to get_recovery_mode_switch() and have
	* them return consistent results during the verified boot path as well
	* as dram initialization. x86 systems ignore the saved dram settings
	* in the recovery path in order to start from a clean slate. Therefore
	* clear the state here since this function is called when memory
	* is known to be up.
	*/
	clear_recovery_mode_switch();
	}
	#if !CONFIG(VBOOT_STARTS_IN_ROMSTAGE)
	ROMSTAGE_CBMEM_INIT_HOOK(vboot_log_and_clear_recovery_mode_switch)
	#endif

	/**
	* Verify and select the firmware in the RW image
	*
	* TODO: Avoid loading a stage twice (once in hash_body & again in load_stage).
	* when per-stage verification is ready.
	*/
	void verstage_main(void)
	{
	struct vb2_context *ctx;
	struct region_device fw_body;
	vb2_error_t rv;

	timestamp_add_now(TS_START_VBOOT);

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

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

	/* 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) &&
	vboot_platform_is_resuming())
	ctx->flags \|= VB2_CONTEXT_S3_RESUME;

	/* 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_START_TPMINIT);
	if (vboot_setup_tpm(ctx) == TPM_SUCCESS)
	antirollback_read_space_firmware(ctx);
	timestamp_add_now(TS_END_TPMINIT);

	/* Enable measured boot mode */
	if (CONFIG(VBOOT_MEASURED_BOOT) &&
	!(ctx->flags & VB2_CONTEXT_S3_RESUME)) {
	if (vboot_init_crtm() != VB2_SUCCESS)
	die_with_post_code(POST_INVALID_ROM,
	"Initializing measured boot mode failed!");
	}

	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;

	/* 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;
	}

	printk(BIOS_INFO, "Reboot requested (%x)\n", rv);
	vboot_save_data(ctx);
	vboot_reboot();
	}

	/* Determine which firmware slot to boot (based on NVRAM) */
	printk(BIOS_INFO, "Phase 2\n");
	rv = vb2api_fw_phase2(ctx);
	if (rv) {
	printk(BIOS_INFO, "Reboot requested (%x)\n", rv);
	vboot_save_data(ctx);
	vboot_reboot();
	}

	/* Try that slot (verify its keyblock and preamble) */
	printk(BIOS_INFO, "Phase 3\n");
	timestamp_add_now(TS_START_VERIFY_SLOT);
	rv = vb2api_fw_phase3(ctx);
	timestamp_add_now(TS_END_VERIFY_SLOT);
	if (rv) {
	printk(BIOS_INFO, "Reboot requested (%x)\n", rv);
	vboot_save_data(ctx);
	vboot_reboot();
	}

	printk(BIOS_INFO, "Phase 4\n");
	rv = vboot_locate_firmware(ctx, &fw_body);
	if (rv)
	die_with_post_code(POST_INVALID_ROM,
	"Failed to read FMAP to locate firmware");

	rv = hash_body(ctx, &fw_body);
	vboot_save_data(ctx);
	if (rv) {
	printk(BIOS_INFO, "Reboot requested (%x)\n", rv);
	vboot_reboot();
	}

	/* Only extend PCRs once on boot. */
	if (!(ctx->flags & VB2_CONTEXT_S3_RESUME)) {
	timestamp_add_now(TS_START_TPMPCR);
	rv = extend_pcrs(ctx);
	if (rv) {
	printk(BIOS_WARNING,
	"Failed to extend TPM PCRs (%#x)\n", rv);
	vb2api_fail(ctx, VB2_RECOVERY_RO_TPM_U_ERROR, rv);
	vboot_save_data(ctx);
	vboot_reboot();
	}
	timestamp_add_now(TS_END_TPMPCR);
	}

	/* Lock TPM */

	timestamp_add_now(TS_START_TPMLOCK);
	rv = antirollback_lock_space_firmware();
	if (rv) {
	printk(BIOS_INFO, "Failed to lock TPM (%x)\n", rv);
	vb2api_fail(ctx, VB2_RECOVERY_RO_TPM_L_ERROR, 0);
	vboot_save_data(ctx);
	vboot_reboot();
	}
	timestamp_add_now(TS_END_TPMLOCK);

	/* Lock rec hash space if available. */
	if (CONFIG(VBOOT_HAS_REC_HASH_SPACE)) {
	rv = antirollback_lock_space_rec_hash();
	if (rv) {
	printk(BIOS_INFO, "Failed to lock rec hash space(%x)\n",
	rv);
	vb2api_fail(ctx, VB2_RECOVERY_RO_TPM_REC_HASH_L_ERROR,
	0);
	vboot_save_data(ctx);
	vboot_reboot();
	}
	}

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

	verstage_main_exit:
	/* If CBMEM is not up yet, let the ROMSTAGE_CBMEM_INIT_HOOK take care
	of running this function. */
	if (ENV_ROMSTAGE && CONFIG(VBOOT_STARTS_IN_ROMSTAGE))
	vboot_log_and_clear_recovery_mode_switch(0);

	/* Save recovery reason in case of unexpected reboots on x86. */
	vboot_save_recovery_reason_vbnv();

	timestamp_add_now(TS_END_VBOOT);
	}