firmware/2lib/2ec_sync.c - third_party/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.
  *
  * EC software sync routines for vboot
  */

 #include "2api.h"
 #include "2common.h"
 #include "2misc.h"
 #include "2nvstorage.h"
 #include "2sysincludes.h"
 #include "vboot_api.h"
 #include "vboot_display.h"
 #include "vboot_kernel.h"

 #define SYNC_FLAG(select)					\
 	((select) == VB_SELECT_FIRMWARE_READONLY ?		\
 	 VB2_SD_FLAG_ECSYNC_EC_RO : VB2_SD_FLAG_ECSYNC_EC_RW)

 /**
  * If no display is available, set DISPLAY_REQUEST in NV space
  */
 static int check_reboot_for_display(struct vb2_context *ctx)
 {
 	if (!(vb2_get_sd(ctx)->flags & VB2_SD_FLAG_DISPLAY_AVAILABLE)) {
 		VB2_DEBUG("Reboot to initialize display\n");
 		vb2_nv_set(ctx, VB2_NV_DISPLAY_REQUEST, 1);
 		return 1;
 	}
 	return 0;
 }

 /**
  * Display the WAIT screen
  */
 static void display_wait_screen(struct vb2_context *ctx)
 {
 	VB2_DEBUG("EC FW update is slow. Show WAIT screen.\n");
 	VbDisplayScreen(ctx, VB_SCREEN_WAIT, 0, NULL);
 }

 /**
  * Set the RECOVERY_REQUEST flag in NV space
  */
 static void request_recovery(struct vb2_context *ctx, uint32_t recovery_request)
 {
 	VB2_DEBUG("request_recovery(%u)\n", recovery_request);

 	vb2_nv_set(ctx, VB2_NV_RECOVERY_REQUEST, recovery_request);
 }

 /**
  * Wrapper around vb2ex_ec_protect() which sets recovery reason on error.
  */
 static vb2_error_t protect_ec(struct vb2_context *ctx,
 			      enum vb2_firmware_selection select)
 {
 	vb2_error_t rv = vb2ex_ec_protect(select);

 	if (rv == VBERROR_EC_REBOOT_TO_RO_REQUIRED) {
 		VB2_DEBUG("vb2ex_ec_protect() needs reboot\n");
 	} else if (rv != VB2_SUCCESS) {
 		VB2_DEBUG("vb2ex_ec_protect() returned %#x\n", rv);
 		request_recovery(ctx, VB2_RECOVERY_EC_PROTECT);
 	}
 	return rv;
 }

 /**
  * Print a hash to debug output
  *
  * @param hash		Pointer to the hash
  * @param hash_size	Size of the hash in bytes
  * @param desc		Description of what's being hashed
  */
 static void print_hash(const uint8_t *hash, uint32_t hash_size,
 		       const char *desc)
 {
 	int i;

 	VB2_DEBUG("%s hash: ", desc);
 	for (i = 0; i < hash_size; i++)
 		VB2_DEBUG_RAW("%02x", hash[i]);
 	VB2_DEBUG_RAW("\n");
 }

 static const char *image_name_to_string(enum vb2_firmware_selection select)
 {
 	switch (select) {
 	case VB_SELECT_FIRMWARE_READONLY:
 		return "RO";
 	case VB_SELECT_FIRMWARE_EC_ACTIVE:
 		return "RW(active)";
 	case VB_SELECT_FIRMWARE_EC_UPDATE:
 		return "RW(update)";
 	default:
 		return "UNKNOWN";
 	}
 }

 /**
  * Check if the hash of the EC code matches the expected hash.
  *
  * @param ctx		Vboot2 context
  * @param select	Which firmware image to check
  * @return VB2_SUCCESS, or non-zero error code.
  */
 static vb2_error_t check_ec_hash(struct vb2_context *ctx,
 				 enum vb2_firmware_selection select)
 {
 	struct vb2_shared_data *sd = vb2_get_sd(ctx);

 	/* Get current EC hash. */
 	const uint8_t *ec_hash = NULL;
 	int ec_hash_size;
 	vb2_error_t rv = vb2ex_ec_hash_image(select, &ec_hash, &ec_hash_size);
 	if (rv) {
 		VB2_DEBUG("vb2ex_ec_hash_image() returned %#x\n", rv);
 		request_recovery(ctx, VB2_RECOVERY_EC_HASH_FAILED);
 		return VB2_ERROR_EC_HASH_IMAGE;
 	}
 	print_hash(ec_hash, ec_hash_size, image_name_to_string(select));

 	/* Get expected EC hash. */
 	const uint8_t *hash = NULL;
 	int hash_size;
 	rv = vb2ex_ec_get_expected_image_hash(select, &hash, &hash_size);
 	if (rv) {
 		VB2_DEBUG("vb2ex_ec_get_expected_image_hash() returned %#x\n", rv);
 		request_recovery(ctx, VB2_RECOVERY_EC_EXPECTED_HASH);
 		return VB2_ERROR_EC_HASH_EXPECTED;
 	}
 	if (ec_hash_size != hash_size) {
 		VB2_DEBUG("EC uses %d-byte hash, but AP-RW contains %d bytes\n",
 			  ec_hash_size, hash_size);
 		request_recovery(ctx, VB2_RECOVERY_EC_HASH_SIZE);
 		return VB2_ERROR_EC_HASH_SIZE;
 	}

 	if (vb2_safe_memcmp(ec_hash, hash, hash_size)) {
 		print_hash(hash, hash_size, "Expected");
 		sd->flags |= SYNC_FLAG(select);
 	}

 	return VB2_SUCCESS;
 }

 /**
  * Update the specified EC and verify the update succeeded
  *
  * @param ctx		Vboot2 context
  * @param select	Which firmware image to check
  * @return VB2_SUCCESS, or non-zero error code.
  */
 static vb2_error_t update_ec(struct vb2_context *ctx,
 			     enum vb2_firmware_selection select)
 {
 	struct vb2_shared_data *sd = vb2_get_sd(ctx);
 	vb2_error_t rv;

 	VB2_DEBUG("Updating %s...\n", image_name_to_string(select));

 	rv = vb2ex_ec_update_image(select);
 	if (rv != VB2_SUCCESS) {
 		VB2_DEBUG("vb2ex_ec_update_image() returned %#x\n", rv);

 		/*
 		 * The EC may know it needs a reboot.  It may need to
 		 * unprotect the region before updating, or may need to
 		 * reboot after updating.  Either way, it's not an error
 		 * requiring recovery mode.
 		 *
 		 * If we fail for any other reason, trigger recovery
 		 * mode.
 		 */
 		if (rv != VBERROR_EC_REBOOT_TO_RO_REQUIRED)
 			request_recovery(ctx, VB2_RECOVERY_EC_UPDATE);

 		return rv;
 	}

 	/* Verify the EC was updated properly */
 	sd->flags &= ~SYNC_FLAG(select);
 	if (check_ec_hash(ctx, select) != VB2_SUCCESS)
 		return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
 	if (sd->flags & SYNC_FLAG(select)) {
 		VB2_DEBUG("Failed to update\n");
 		request_recovery(ctx, VB2_RECOVERY_EC_UPDATE);
 		return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
 	}

 	return VB2_SUCCESS;
 }

 /**
  * Set VB2_SD_FLAG_ECSYNC_EC_IN_RW flag for the EC
  *
  * @param ctx		Vboot2 context
  * @return VB2_SUCCESS, or non-zero if error.
  */
 static vb2_error_t check_ec_active(struct vb2_context *ctx)
 {
 	struct vb2_shared_data *sd = vb2_get_sd(ctx);
 	int in_rw = 0;
 	/*
 	 * We don't use vb2ex_ec_trusted, which checks EC_IN_RW. It is
 	 * controlled by cr50 but on some platforms, cr50 can't know when a EC
 	 * resets. So, we trust what EC-RW says. If it lies it's in RO, we'll
 	 * flash RW while it's in RW.
 	 */
 	vb2_error_t rv = vb2ex_ec_running_rw(&in_rw);
 	/* If we couldn't determine where the EC was, reboot to recovery. */
 	if (rv != VB2_SUCCESS) {
 		VB2_DEBUG("vb2ex_ec_running_rw() returned %#x\n", rv);
 		request_recovery(ctx, VB2_RECOVERY_EC_UNKNOWN_IMAGE);
 		return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
 	}

 	if (in_rw)
 		sd->flags |= VB2_SD_FLAG_ECSYNC_EC_IN_RW;

 	return VB2_SUCCESS;
 }

 #define RO_RETRIES 2  /* Maximum times to retry flashing RO */

 /**
  * Sync, jump, and protect EC device
  *
  * @param ctx		Vboot2 context
  * @return VB2_SUCCESS, or non-zero if error.
  */
 static vb2_error_t sync_ec(struct vb2_context *ctx)
 {
 	struct vb2_shared_data *sd = vb2_get_sd(ctx);
 	int is_rw_ab = ctx->flags & VB2_CONTEXT_EC_EFS;
 	vb2_error_t rv;

 	const enum vb2_firmware_selection select_rw = is_rw_ab ?
 		VB_SELECT_FIRMWARE_EC_UPDATE :
 		VB_SELECT_FIRMWARE_EC_ACTIVE;
 	VB2_DEBUG("select_rw=%d\n", select_rw);

 	/* Update the RW Image */
 	if (sd->flags & SYNC_FLAG(select_rw)) {
 		if (VB2_SUCCESS != update_ec(ctx, select_rw))
 			return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
 		/* Updated successfully. Cold reboot to switch to the new RW.
 		 * TODO: Switch slot and proceed if EC is still in RO. */
 		if (is_rw_ab) {
 			VB2_DEBUG("Rebooting to jump to new EC-RW\n");
 			return VBERROR_EC_REBOOT_TO_SWITCH_RW;
 		}
 	}

 	/* Tell EC to jump to its RW image */
 	if (!(sd->flags & VB2_SD_FLAG_ECSYNC_EC_IN_RW)) {
 		VB2_DEBUG("jumping to EC-RW\n");
 		rv = vb2ex_ec_jump_to_rw();
 		if (rv != VB2_SUCCESS) {
 			VB2_DEBUG("vb2ex_ec_jump_to_rw() returned %x\n", rv);

 			/*
 			 * If a previous AP boot has called
 			 * vb2ex_ec_disable_jump(), we need to reboot the EC to
 			 * unlock the ability to jump to the RW firmware.
 			 *
 			 * All other errors trigger recovery mode.
 			 */
 			if (rv != VBERROR_EC_REBOOT_TO_RO_REQUIRED)
 				request_recovery(ctx, VB2_RECOVERY_EC_JUMP_RW);

 			return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
 		}
 	}

 	/* Might need to update EC-RO */
 	if (sd->flags & VB2_SD_FLAG_ECSYNC_EC_RO) {
 		VB2_DEBUG("RO Software Sync\n");

 		/* Reset RO Software Sync NV flag */
 		vb2_nv_set(ctx, VB2_NV_TRY_RO_SYNC, 0);

 		/*
 		 * Get the current recovery request (if any).  This gets
 		 * overwritten by a failed try.  If a later try succeeds, we'll
 		 * need to restore this request (or the lack of a request), or
 		 * else we'll end up in recovery mode even though RO software
 		 * sync did eventually succeed.
 		 */
 		uint32_t recovery_request =
 			vb2_nv_get(ctx, VB2_NV_RECOVERY_REQUEST);

 		/* Update the RO Image. */
 		int num_tries;
 		for (num_tries = 0; num_tries < RO_RETRIES; num_tries++) {
 			if (VB2_SUCCESS ==
 			    update_ec(ctx, VB_SELECT_FIRMWARE_READONLY))
 				break;
 		}
 		if (num_tries == RO_RETRIES) {
 			/* Ran out of tries */
 			return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
 		} else if (num_tries) {
 			/*
 			 * Update succeeded after a failure, so we've polluted
 			 * the recovery request.  Restore it.
 			 */
 			request_recovery(ctx, recovery_request);
 		}
 	}

 	/* Protect RO flash */
 	rv = protect_ec(ctx, VB_SELECT_FIRMWARE_READONLY);
 	if (rv != VB2_SUCCESS)
 		return rv;

 	/* Protect RW flash */
 	rv = protect_ec(ctx, select_rw);
 	if (rv != VB2_SUCCESS)
 		return rv;

 	/* Disable further sysjumps */
 	rv = vb2ex_ec_disable_jump();
 	if (rv != VB2_SUCCESS) {
 		VB2_DEBUG("vb2ex_ec_disable_jump() returned %#x\n", rv);
 		request_recovery(ctx, VB2_RECOVERY_EC_SOFTWARE_SYNC);
 		return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
 	}

 	return rv;
 }

 /**
  * EC sync, phase 1
  *
  * This checks whether the EC is running the correct image to do EC sync, and
  * whether any updates are necessary.
  *
  * @param ctx		Vboot2 context
  * @return VB2_SUCCESS, VBERROR_EC_REBOOT_TO_RO_REQUIRED if the EC must
  * reboot back to its RO code to continue EC sync, or other non-zero error
  * code.
  */
 static vb2_error_t ec_sync_phase1(struct vb2_context *ctx)
 {
 	struct vb2_shared_data *sd = vb2_get_sd(ctx);
 	struct vb2_gbb_header *gbb = vb2_get_gbb(ctx);

 	/* Reasons not to do sync at all */
 	if (!(ctx->flags & VB2_CONTEXT_EC_SYNC_SUPPORTED))
 		return VB2_SUCCESS;
 	if (gbb->flags & VB2_GBB_FLAG_DISABLE_EC_SOFTWARE_SYNC)
 		return VB2_SUCCESS;

 	/* Set VB2_SD_FLAG_ECSYNC_EC_IN_RW flag */
 	if (check_ec_active(ctx))
 		return VBERROR_EC_REBOOT_TO_RO_REQUIRED;

 	/* Check if we need to update RW.  Failures trigger recovery mode. */
 	if (check_ec_hash(ctx, VB_SELECT_FIRMWARE_EC_ACTIVE))
 		return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
 	/* See if we need to update EC-RO. */
 	if (vb2_nv_get(ctx, VB2_NV_TRY_RO_SYNC) &&
 	    check_ec_hash(ctx, VB_SELECT_FIRMWARE_READONLY)) {
 		return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
 	}

 	/*
 	 * If we're in RW, we need to reboot back to RO because RW can't be
 	 * updated while we're running it.
 	 *
 	 * If EC supports RW-A/B slots, we can proceed but we need
 	 * to jump to the new RW version later.
 	 */
 	if ((sd->flags & VB2_SD_FLAG_ECSYNC_EC_RW) &&
 	    (sd->flags & VB2_SD_FLAG_ECSYNC_EC_IN_RW) &&
 	    !(ctx->flags & VB2_CONTEXT_EC_EFS)) {
 		return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
 	}

 	return VB2_SUCCESS;
 }

 /**
  * Returns non-zero if the EC will perform a slow update.
  *
  * This is only valid after calling ec_sync_phase1(), before calling
  * sync_ec().
  *
  * @param ctx		Vboot2 context
  * @return non-zero if a slow update will be done; zero if no update or a
  * fast update.
  */
 static int ec_will_update_slowly(struct vb2_context *ctx)
 {
 	struct vb2_shared_data *sd = vb2_get_sd(ctx);

 	return (((sd->flags & VB2_SD_FLAG_ECSYNC_EC_RO) ||
 		 (sd->flags & VB2_SD_FLAG_ECSYNC_EC_RW)) &&
 		(ctx->flags & VB2_CONTEXT_EC_SYNC_SLOW));
 }

 /**
  * determine if we can update the EC
  *
  * @param ctx		Vboot2 context
  * @return boolean (true iff we can update the EC)
  */

 static int ec_sync_allowed(struct vb2_context *ctx)
 {
 	struct vb2_shared_data *sd = vb2_get_sd(ctx);
 	struct vb2_gbb_header *gbb = vb2_get_gbb(ctx);

 	/* Reasons not to do sync at all */
 	if (!(ctx->flags & VB2_CONTEXT_EC_SYNC_SUPPORTED))
 		return 0;
 	if (gbb->flags & VB2_GBB_FLAG_DISABLE_EC_SOFTWARE_SYNC)
 		return 0;
 	if (sd->recovery_reason)
 		return 0;
 	return 1;
 }

 /**
  * EC sync, phase 2
  *
  * This updates the EC if necessary, makes sure it has protected its image(s),
  * and makes sure it has jumped to the correct image.
  *
  * If ec_will_update_slowly(), it is suggested that the caller display a
  * warning screen before calling phase 2.
  *
  * @param ctx		Vboot2 context
  * @return VB2_SUCCESS, VBERROR_EC_REBOOT_TO_RO_REQUIRED if the EC must
  * reboot back to its RO code to continue EC sync, or other non-zero error
  * code.
  */
 static vb2_error_t ec_sync_phase2(struct vb2_context *ctx)
 {
 	if (!ec_sync_allowed(ctx))
 		return VB2_SUCCESS;

 	/* Handle updates and jumps for EC */
 	return sync_ec(ctx);
 }

 vb2_error_t vb2api_ec_sync(struct vb2_context *ctx)
 {
 	struct vb2_shared_data *sd = vb2_get_sd(ctx);
 	vb2_error_t rv;

 	/*
 	 * If the status indicates that the EC has already gone through
 	 * software sync this boot, then don't do it again.
 	 */
 	if (sd->status & VB2_SD_STATUS_EC_SYNC_COMPLETE) {
 		VB2_DEBUG("EC software sync already performed this boot, skipping\n");
 		return VB2_SUCCESS;
 	}

 	/*
 	 * If the device is in recovery mode, then EC sync should
 	 * not be performed.
 	 */
 	if (ctx->flags & VB2_CONTEXT_RECOVERY_MODE) {
 		VB2_DEBUG("In recovery mode, skipping EC sync\n");
 		return VB2_SUCCESS;
 	}

 	/* Phase 1; this determines if we need an update */
 	vb2_error_t phase1_rv = ec_sync_phase1(ctx);
 	int need_wait_screen = ec_will_update_slowly(ctx);

 	if (need_wait_screen && check_reboot_for_display(ctx))
 		return VBERROR_REBOOT_REQUIRED;

 	if (phase1_rv)
 		return phase1_rv;

 	if (need_wait_screen)
 		display_wait_screen(ctx);

 	/* Phase 2; Applies update and/or jumps to the correct EC image */
 	rv = ec_sync_phase2(ctx);
 	if (rv)
 		return rv;

 	/* Phase 3; Let the platform know that EC software sync is now done */
 	rv = vb2ex_ec_vboot_done(ctx);
 	if (rv)
 		return rv;

 	/* Establish that EC software sync is complete and successful */
 	sd->status |= VB2_SD_STATUS_EC_SYNC_COMPLETE;

 	return VB2_SUCCESS;
 }
	/* 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.
	*
	* EC software sync routines for vboot
	*/

	#include "2api.h"
	#include "2common.h"
	#include "2misc.h"
	#include "2nvstorage.h"
	#include "2sysincludes.h"
	#include "vboot_api.h"
	#include "vboot_display.h"
	#include "vboot_kernel.h"

	#define SYNC_FLAG(select) \
	((select) == VB_SELECT_FIRMWARE_READONLY ? \
	VB2_SD_FLAG_ECSYNC_EC_RO : VB2_SD_FLAG_ECSYNC_EC_RW)

	/**
	* If no display is available, set DISPLAY_REQUEST in NV space
	*/
	static int check_reboot_for_display(struct vb2_context *ctx)
	{
	if (!(vb2_get_sd(ctx)->flags & VB2_SD_FLAG_DISPLAY_AVAILABLE)) {
	VB2_DEBUG("Reboot to initialize display\n");
	vb2_nv_set(ctx, VB2_NV_DISPLAY_REQUEST, 1);
	return 1;
	}
	return 0;
	}

	/**
	* Display the WAIT screen
	*/
	static void display_wait_screen(struct vb2_context *ctx)
	{
	VB2_DEBUG("EC FW update is slow. Show WAIT screen.\n");
	VbDisplayScreen(ctx, VB_SCREEN_WAIT, 0, NULL);
	}

	/**
	* Set the RECOVERY_REQUEST flag in NV space
	*/
	static void request_recovery(struct vb2_context *ctx, uint32_t recovery_request)
	{
	VB2_DEBUG("request_recovery(%u)\n", recovery_request);

	vb2_nv_set(ctx, VB2_NV_RECOVERY_REQUEST, recovery_request);
	}

	/**
	* Wrapper around vb2ex_ec_protect() which sets recovery reason on error.
	*/
	static vb2_error_t protect_ec(struct vb2_context *ctx,
	enum vb2_firmware_selection select)
	{
	vb2_error_t rv = vb2ex_ec_protect(select);

	if (rv == VBERROR_EC_REBOOT_TO_RO_REQUIRED) {
	VB2_DEBUG("vb2ex_ec_protect() needs reboot\n");
	} else if (rv != VB2_SUCCESS) {
	VB2_DEBUG("vb2ex_ec_protect() returned %#x\n", rv);
	request_recovery(ctx, VB2_RECOVERY_EC_PROTECT);
	}
	return rv;
	}

	/**
	* Print a hash to debug output
	*
	* @param hash Pointer to the hash
	* @param hash_size Size of the hash in bytes
	* @param desc Description of what's being hashed
	*/
	static void print_hash(const uint8_t *hash, uint32_t hash_size,
	const char *desc)
	{
	int i;

	VB2_DEBUG("%s hash: ", desc);
	for (i = 0; i < hash_size; i++)
	VB2_DEBUG_RAW("%02x", hash[i]);
	VB2_DEBUG_RAW("\n");
	}

	static const char *image_name_to_string(enum vb2_firmware_selection select)
	{
	switch (select) {
	case VB_SELECT_FIRMWARE_READONLY:
	return "RO";
	case VB_SELECT_FIRMWARE_EC_ACTIVE:
	return "RW(active)";
	case VB_SELECT_FIRMWARE_EC_UPDATE:
	return "RW(update)";
	default:
	return "UNKNOWN";
	}
	}

	/**
	* Check if the hash of the EC code matches the expected hash.
	*
	* @param ctx Vboot2 context
	* @param select Which firmware image to check
	* @return VB2_SUCCESS, or non-zero error code.
	*/
	static vb2_error_t check_ec_hash(struct vb2_context *ctx,
	enum vb2_firmware_selection select)
	{
	struct vb2_shared_data *sd = vb2_get_sd(ctx);

	/* Get current EC hash. */
	const uint8_t *ec_hash = NULL;
	int ec_hash_size;
	vb2_error_t rv = vb2ex_ec_hash_image(select, &ec_hash, &ec_hash_size);
	if (rv) {
	VB2_DEBUG("vb2ex_ec_hash_image() returned %#x\n", rv);
	request_recovery(ctx, VB2_RECOVERY_EC_HASH_FAILED);
	return VB2_ERROR_EC_HASH_IMAGE;
	}
	print_hash(ec_hash, ec_hash_size, image_name_to_string(select));

	/* Get expected EC hash. */
	const uint8_t *hash = NULL;
	int hash_size;
	rv = vb2ex_ec_get_expected_image_hash(select, &hash, &hash_size);
	if (rv) {
	VB2_DEBUG("vb2ex_ec_get_expected_image_hash() returned %#x\n", rv);
	request_recovery(ctx, VB2_RECOVERY_EC_EXPECTED_HASH);
	return VB2_ERROR_EC_HASH_EXPECTED;
	}
	if (ec_hash_size != hash_size) {
	VB2_DEBUG("EC uses %d-byte hash, but AP-RW contains %d bytes\n",
	ec_hash_size, hash_size);
	request_recovery(ctx, VB2_RECOVERY_EC_HASH_SIZE);
	return VB2_ERROR_EC_HASH_SIZE;
	}

	if (vb2_safe_memcmp(ec_hash, hash, hash_size)) {
	print_hash(hash, hash_size, "Expected");
	sd->flags \|= SYNC_FLAG(select);
	}

	return VB2_SUCCESS;
	}

	/**
	* Update the specified EC and verify the update succeeded
	*
	* @param ctx Vboot2 context
	* @param select Which firmware image to check
	* @return VB2_SUCCESS, or non-zero error code.
	*/
	static vb2_error_t update_ec(struct vb2_context *ctx,
	enum vb2_firmware_selection select)
	{
	struct vb2_shared_data *sd = vb2_get_sd(ctx);
	vb2_error_t rv;

	VB2_DEBUG("Updating %s...\n", image_name_to_string(select));

	rv = vb2ex_ec_update_image(select);
	if (rv != VB2_SUCCESS) {
	VB2_DEBUG("vb2ex_ec_update_image() returned %#x\n", rv);

	/*
	* The EC may know it needs a reboot. It may need to
	* unprotect the region before updating, or may need to
	* reboot after updating. Either way, it's not an error
	* requiring recovery mode.
	*
	* If we fail for any other reason, trigger recovery
	* mode.
	*/
	if (rv != VBERROR_EC_REBOOT_TO_RO_REQUIRED)
	request_recovery(ctx, VB2_RECOVERY_EC_UPDATE);

	return rv;
	}

	/* Verify the EC was updated properly */
	sd->flags &= ~SYNC_FLAG(select);
	if (check_ec_hash(ctx, select) != VB2_SUCCESS)
	return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
	if (sd->flags & SYNC_FLAG(select)) {
	VB2_DEBUG("Failed to update\n");
	request_recovery(ctx, VB2_RECOVERY_EC_UPDATE);
	return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
	}

	return VB2_SUCCESS;
	}

	/**
	* Set VB2_SD_FLAG_ECSYNC_EC_IN_RW flag for the EC
	*
	* @param ctx Vboot2 context
	* @return VB2_SUCCESS, or non-zero if error.
	*/
	static vb2_error_t check_ec_active(struct vb2_context *ctx)
	{
	struct vb2_shared_data *sd = vb2_get_sd(ctx);
	int in_rw = 0;
	/*
	* We don't use vb2ex_ec_trusted, which checks EC_IN_RW. It is
	* controlled by cr50 but on some platforms, cr50 can't know when a EC
	* resets. So, we trust what EC-RW says. If it lies it's in RO, we'll
	* flash RW while it's in RW.
	*/
	vb2_error_t rv = vb2ex_ec_running_rw(&in_rw);
	/* If we couldn't determine where the EC was, reboot to recovery. */
	if (rv != VB2_SUCCESS) {
	VB2_DEBUG("vb2ex_ec_running_rw() returned %#x\n", rv);
	request_recovery(ctx, VB2_RECOVERY_EC_UNKNOWN_IMAGE);
	return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
	}

	if (in_rw)
	sd->flags \|= VB2_SD_FLAG_ECSYNC_EC_IN_RW;

	return VB2_SUCCESS;
	}

	#define RO_RETRIES 2 /* Maximum times to retry flashing RO */

	/**
	* Sync, jump, and protect EC device
	*
	* @param ctx Vboot2 context
	* @return VB2_SUCCESS, or non-zero if error.
	*/
	static vb2_error_t sync_ec(struct vb2_context *ctx)
	{
	struct vb2_shared_data *sd = vb2_get_sd(ctx);
	int is_rw_ab = ctx->flags & VB2_CONTEXT_EC_EFS;
	vb2_error_t rv;

	const enum vb2_firmware_selection select_rw = is_rw_ab ?
	VB_SELECT_FIRMWARE_EC_UPDATE :
	VB_SELECT_FIRMWARE_EC_ACTIVE;
	VB2_DEBUG("select_rw=%d\n", select_rw);

	/* Update the RW Image */
	if (sd->flags & SYNC_FLAG(select_rw)) {
	if (VB2_SUCCESS != update_ec(ctx, select_rw))
	return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
	/* Updated successfully. Cold reboot to switch to the new RW.
	* TODO: Switch slot and proceed if EC is still in RO. */
	if (is_rw_ab) {
	VB2_DEBUG("Rebooting to jump to new EC-RW\n");
	return VBERROR_EC_REBOOT_TO_SWITCH_RW;
	}
	}

	/* Tell EC to jump to its RW image */
	if (!(sd->flags & VB2_SD_FLAG_ECSYNC_EC_IN_RW)) {
	VB2_DEBUG("jumping to EC-RW\n");
	rv = vb2ex_ec_jump_to_rw();
	if (rv != VB2_SUCCESS) {
	VB2_DEBUG("vb2ex_ec_jump_to_rw() returned %x\n", rv);

	/*
	* If a previous AP boot has called
	* vb2ex_ec_disable_jump(), we need to reboot the EC to
	* unlock the ability to jump to the RW firmware.
	*
	* All other errors trigger recovery mode.
	*/
	if (rv != VBERROR_EC_REBOOT_TO_RO_REQUIRED)
	request_recovery(ctx, VB2_RECOVERY_EC_JUMP_RW);

	return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
	}
	}

	/* Might need to update EC-RO */
	if (sd->flags & VB2_SD_FLAG_ECSYNC_EC_RO) {
	VB2_DEBUG("RO Software Sync\n");

	/* Reset RO Software Sync NV flag */
	vb2_nv_set(ctx, VB2_NV_TRY_RO_SYNC, 0);

	/*
	* Get the current recovery request (if any). This gets
	* overwritten by a failed try. If a later try succeeds, we'll
	* need to restore this request (or the lack of a request), or
	* else we'll end up in recovery mode even though RO software
	* sync did eventually succeed.
	*/
	uint32_t recovery_request =
	vb2_nv_get(ctx, VB2_NV_RECOVERY_REQUEST);

	/* Update the RO Image. */
	int num_tries;
	for (num_tries = 0; num_tries < RO_RETRIES; num_tries++) {
	if (VB2_SUCCESS ==
	update_ec(ctx, VB_SELECT_FIRMWARE_READONLY))
	break;
	}
	if (num_tries == RO_RETRIES) {
	/* Ran out of tries */
	return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
	} else if (num_tries) {
	/*
	* Update succeeded after a failure, so we've polluted
	* the recovery request. Restore it.
	*/
	request_recovery(ctx, recovery_request);
	}
	}

	/* Protect RO flash */
	rv = protect_ec(ctx, VB_SELECT_FIRMWARE_READONLY);
	if (rv != VB2_SUCCESS)
	return rv;

	/* Protect RW flash */
	rv = protect_ec(ctx, select_rw);
	if (rv != VB2_SUCCESS)
	return rv;

	/* Disable further sysjumps */
	rv = vb2ex_ec_disable_jump();
	if (rv != VB2_SUCCESS) {
	VB2_DEBUG("vb2ex_ec_disable_jump() returned %#x\n", rv);
	request_recovery(ctx, VB2_RECOVERY_EC_SOFTWARE_SYNC);
	return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
	}

	return rv;
	}

	/**
	* EC sync, phase 1
	*
	* This checks whether the EC is running the correct image to do EC sync, and
	* whether any updates are necessary.
	*
	* @param ctx Vboot2 context
	* @return VB2_SUCCESS, VBERROR_EC_REBOOT_TO_RO_REQUIRED if the EC must
	* reboot back to its RO code to continue EC sync, or other non-zero error
	* code.
	*/
	static vb2_error_t ec_sync_phase1(struct vb2_context *ctx)
	{
	struct vb2_shared_data *sd = vb2_get_sd(ctx);
	struct vb2_gbb_header *gbb = vb2_get_gbb(ctx);

	/* Reasons not to do sync at all */
	if (!(ctx->flags & VB2_CONTEXT_EC_SYNC_SUPPORTED))
	return VB2_SUCCESS;
	if (gbb->flags & VB2_GBB_FLAG_DISABLE_EC_SOFTWARE_SYNC)
	return VB2_SUCCESS;

	/* Set VB2_SD_FLAG_ECSYNC_EC_IN_RW flag */
	if (check_ec_active(ctx))
	return VBERROR_EC_REBOOT_TO_RO_REQUIRED;

	/* Check if we need to update RW. Failures trigger recovery mode. */
	if (check_ec_hash(ctx, VB_SELECT_FIRMWARE_EC_ACTIVE))
	return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
	/* See if we need to update EC-RO. */
	if (vb2_nv_get(ctx, VB2_NV_TRY_RO_SYNC) &&
	check_ec_hash(ctx, VB_SELECT_FIRMWARE_READONLY)) {
	return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
	}

	/*
	* If we're in RW, we need to reboot back to RO because RW can't be
	* updated while we're running it.
	*
	* If EC supports RW-A/B slots, we can proceed but we need
	* to jump to the new RW version later.
	*/
	if ((sd->flags & VB2_SD_FLAG_ECSYNC_EC_RW) &&
	(sd->flags & VB2_SD_FLAG_ECSYNC_EC_IN_RW) &&
	!(ctx->flags & VB2_CONTEXT_EC_EFS)) {
	return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
	}

	return VB2_SUCCESS;
	}

	/**
	* Returns non-zero if the EC will perform a slow update.
	*
	* This is only valid after calling ec_sync_phase1(), before calling
	* sync_ec().
	*
	* @param ctx Vboot2 context
	* @return non-zero if a slow update will be done; zero if no update or a
	* fast update.
	*/
	static int ec_will_update_slowly(struct vb2_context *ctx)
	{
	struct vb2_shared_data *sd = vb2_get_sd(ctx);

	return (((sd->flags & VB2_SD_FLAG_ECSYNC_EC_RO) \|\|
	(sd->flags & VB2_SD_FLAG_ECSYNC_EC_RW)) &&
	(ctx->flags & VB2_CONTEXT_EC_SYNC_SLOW));
	}

	/**
	* determine if we can update the EC
	*
	* @param ctx Vboot2 context
	* @return boolean (true iff we can update the EC)
	*/

	static int ec_sync_allowed(struct vb2_context *ctx)
	{
	struct vb2_shared_data *sd = vb2_get_sd(ctx);
	struct vb2_gbb_header *gbb = vb2_get_gbb(ctx);

	/* Reasons not to do sync at all */
	if (!(ctx->flags & VB2_CONTEXT_EC_SYNC_SUPPORTED))
	return 0;
	if (gbb->flags & VB2_GBB_FLAG_DISABLE_EC_SOFTWARE_SYNC)
	return 0;
	if (sd->recovery_reason)
	return 0;
	return 1;
	}

	/**
	* EC sync, phase 2
	*
	* This updates the EC if necessary, makes sure it has protected its image(s),
	* and makes sure it has jumped to the correct image.
	*
	* If ec_will_update_slowly(), it is suggested that the caller display a
	* warning screen before calling phase 2.
	*
	* @param ctx Vboot2 context
	* @return VB2_SUCCESS, VBERROR_EC_REBOOT_TO_RO_REQUIRED if the EC must
	* reboot back to its RO code to continue EC sync, or other non-zero error
	* code.
	*/
	static vb2_error_t ec_sync_phase2(struct vb2_context *ctx)
	{
	if (!ec_sync_allowed(ctx))
	return VB2_SUCCESS;

	/* Handle updates and jumps for EC */
	return sync_ec(ctx);
	}

	vb2_error_t vb2api_ec_sync(struct vb2_context *ctx)
	{
	struct vb2_shared_data *sd = vb2_get_sd(ctx);
	vb2_error_t rv;

	/*
	* If the status indicates that the EC has already gone through
	* software sync this boot, then don't do it again.
	*/
	if (sd->status & VB2_SD_STATUS_EC_SYNC_COMPLETE) {
	VB2_DEBUG("EC software sync already performed this boot, skipping\n");
	return VB2_SUCCESS;
	}

	/*
	* If the device is in recovery mode, then EC sync should
	* not be performed.
	*/
	if (ctx->flags & VB2_CONTEXT_RECOVERY_MODE) {
	VB2_DEBUG("In recovery mode, skipping EC sync\n");
	return VB2_SUCCESS;
	}

	/* Phase 1; this determines if we need an update */
	vb2_error_t phase1_rv = ec_sync_phase1(ctx);
	int need_wait_screen = ec_will_update_slowly(ctx);

	if (need_wait_screen && check_reboot_for_display(ctx))
	return VBERROR_REBOOT_REQUIRED;

	if (phase1_rv)
	return phase1_rv;

	if (need_wait_screen)
	display_wait_screen(ctx);

	/* Phase 2; Applies update and/or jumps to the correct EC image */
	rv = ec_sync_phase2(ctx);
	if (rv)
	return rv;

	/* Phase 3; Let the platform know that EC software sync is now done */
	rv = vb2ex_ec_vboot_done(ctx);
	if (rv)
	return rv;

	/* Establish that EC software sync is complete and successful */
	sd->status \|= VB2_SD_STATUS_EC_SYNC_COMPLETE;

	return VB2_SUCCESS;
	}