path: root/firmware/lib/ec_sync.c

/* 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 "2sysincludes.h"
#include "2common.h"
#include "2misc.h"
#include "2nvstorage.h"

#include "ec_sync.h"
#include "vboot_api.h"
#include "vboot_common.h"
#include "vboot_kernel.h"

#define VB2_SD_FLAG_ECSYNC_RW					\
	(VB2_SD_FLAG_ECSYNC_EC_RW | VB2_SD_FLAG_ECSYNC_PD_RW)
#define VB2_SD_FLAG_ECSYNC_ANY					\
	(VB2_SD_FLAG_ECSYNC_EC_RO | VB2_SD_FLAG_ECSYNC_RW)
#define VB2_SD_FLAG_ECSYNC_IN_RW					\
	(VB2_SD_FLAG_ECSYNC_EC_IN_RW | VB2_SD_FLAG_ECSYNC_PD_IN_RW)

#define IN_RW(devidx)							\
	((devidx) ? VB2_SD_FLAG_ECSYNC_PD_IN_RW : VB2_SD_FLAG_ECSYNC_EC_IN_RW)

#define WHICH_EC(devidx, select) \
	((select) == VB_SELECT_FIRMWARE_READONLY ? VB2_SD_FLAG_ECSYNC_EC_RO : \
	 ((devidx) ? VB2_SD_FLAG_ECSYNC_PD_RW : VB2_SD_FLAG_ECSYNC_EC_RW))

/* PD doesn't support RW A/B */
#define RW_AB(devidx) ((devidx) ? 0 : VB2_CONTEXT_EC_EFS)

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 VbExEcProtect() which sets recovery reason on error.
 */
static vb2_error_t protect_ec(struct vb2_context *ctx, int devidx,
			      enum VbSelectFirmware_t select)
{
	vb2_error_t rv = VbExEcProtect(devidx, select);

	if (rv == VBERROR_EC_REBOOT_TO_RO_REQUIRED) {
		VB2_DEBUG("VbExEcProtect() needs reboot\n");
	} else if (rv != VB2_SUCCESS) {
		VB2_DEBUG("VbExEcProtect() returned %d\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 VbSelectFirmware_t 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 devidx	Index of EC device to check
 * @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, int devidx,
				 enum VbSelectFirmware_t 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 = VbExEcHashImage(devidx, select, &ec_hash,
					 &ec_hash_size);
	if (rv) {
		VB2_DEBUG("VbExEcHashImage() returned %d\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 = VbExEcGetExpectedImageHash(devidx, select, &hash, &hash_size);
	if (rv) {
		VB2_DEBUG("VbExEcGetExpectedImageHash() returned %d\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 |= WHICH_EC(devidx, select);
	}

	return VB2_SUCCESS;
}

/**
 * Update the specified EC and verify the update succeeded
 *
 * @param ctx		Vboot2 context
 * @param devidx	Index of EC device to check
 * @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, int devidx,
			     enum VbSelectFirmware_t select)
{
	struct vb2_shared_data *sd = vb2_get_sd(ctx);

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

	/* Get expected EC image */
	const uint8_t *want = NULL;
	int want_size;
	vb2_error_t rv = VbExEcGetExpectedImage(devidx, select, &want,
						&want_size);
	if (rv) {
		VB2_DEBUG("VbExEcGetExpectedImage() returned %d\n", rv);
		request_recovery(ctx, VB2_RECOVERY_EC_EXPECTED_IMAGE);
		return rv;
	}
	VB2_DEBUG("image len = %d\n", want_size);

	rv = VbExEcUpdateImage(devidx, select, want, want_size);
	if (rv != VB2_SUCCESS) {
		VB2_DEBUG("VbExEcUpdateImage() returned %d\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 &= ~WHICH_EC(devidx, select);
	if (check_ec_hash(ctx, devidx, select) != VB2_SUCCESS)
		return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
	if (sd->flags & WHICH_EC(devidx, 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 IN_RW flag for a EC
 *
 * @param ctx		Vboot2 context
 * @param devidx	Which device (EC=0, PD=1)
 */
static vb2_error_t check_ec_active(struct vb2_context *ctx, int devidx)
{
	struct vb2_shared_data *sd = vb2_get_sd(ctx);
	int in_rw = 0;
	/*
	 * We don't use VbExTrustEC, 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 = VbExEcRunningRW(devidx, &in_rw);

	/* If we couldn't determine where the EC was, reboot to recovery. */
	if (rv != VB2_SUCCESS) {
		VB2_DEBUG("VbExEcRunningRW() returned %d\n", rv);
		request_recovery(ctx, VB2_RECOVERY_EC_UNKNOWN_IMAGE);
		return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
	}

	if (in_rw)
		sd->flags |= IN_RW(devidx);

	return VB2_SUCCESS;
}

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

/**
 * Sync, jump, and protect one EC device
 *
 * @param ctx		Vboot2 context
 * @param devidx	Which device (EC=0, PD=1)
 * @return VB2_SUCCESS, or non-zero if error.
 */
static vb2_error_t sync_one_ec(struct vb2_context *ctx, int devidx)
{
	struct vb2_shared_data *sd = vb2_get_sd(ctx);
	int is_rw_ab = ctx->flags & RW_AB(devidx);
	vb2_error_t rv;

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

	/* Update the RW Image */
	if (sd->flags & WHICH_EC(devidx, select_rw)) {
		if (VB2_SUCCESS != update_ec(ctx, devidx, 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 & IN_RW(devidx))) {
		VB2_DEBUG("jumping to EC-RW\n");
		rv = VbExEcJumpToRW(devidx);
		if (rv != VB2_SUCCESS) {
			VB2_DEBUG("VbExEcJumpToRW() returned %x\n", rv);

			/*
			 * If a previous AP boot has called VbExEcStayInRO(),
			 * 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 (but not PD-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, devidx, 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, devidx, VB_SELECT_FIRMWARE_READONLY);
	if (rv != VB2_SUCCESS)
		return rv;

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

	rv = VbExEcDisableJump(devidx);
	if (rv != VB2_SUCCESS) {
		VB2_DEBUG("VbExEcDisableJump() returned %d\n", rv);
		request_recovery(ctx, VB2_RECOVERY_EC_SOFTWARE_SYNC);
		return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
	}

	return rv;
}

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;

#ifdef PD_SYNC
	const int do_pd_sync = !(gbb->flags &
				 VB2_GBB_FLAG_DISABLE_PD_SOFTWARE_SYNC);
#else
	const int do_pd_sync = 0;
#endif

	/* Set IN_RW flags */
	if (check_ec_active(ctx, 0))
		return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
	if (do_pd_sync && check_ec_active(ctx, 1))
		return VBERROR_EC_REBOOT_TO_RO_REQUIRED;

	/* Check if we need to update RW.  Failures trigger recovery mode. */
	if (check_ec_hash(ctx, 0, VB_SELECT_FIRMWARE_EC_ACTIVE))
		return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
	if (do_pd_sync && check_ec_hash(ctx, 1, VB_SELECT_FIRMWARE_EC_ACTIVE))
		return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
	/*
	 * See if we need to update EC-RO (devidx=0).
	 *
	 * If we want to extend this in the future to update PD-RO, we'll use a
	 * different NV flag so we can track EC-RO and PD-RO updates
	 * separately.
	 */
	if (vb2_nv_get(ctx, VB2_NV_TRY_RO_SYNC) &&
	    check_ec_hash(ctx, 0, 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_RW) &&
	    (sd->flags & VB2_SD_FLAG_ECSYNC_IN_RW) &&
	    !(ctx->flags & VB2_CONTEXT_EC_EFS)) {
		return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
	}

	return VB2_SUCCESS;
}

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_ANY) &&
		(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;
}

vb2_error_t ec_sync_check_aux_fw(struct vb2_context *ctx,
				 VbAuxFwUpdateSeverity_t *severity)
{
	struct vb2_gbb_header *gbb = vb2_get_gbb(ctx);

	/* If we're not updating the EC, skip aux fw syncs as well */
	if (!ec_sync_allowed(ctx) ||
	    (gbb->flags & VB2_GBB_FLAG_DISABLE_PD_SOFTWARE_SYNC)) {
		*severity = VB_AUX_FW_NO_UPDATE;
		return VB2_SUCCESS;
	}
	return VbExCheckAuxFw(severity);
}

vb2_error_t ec_sync_update_aux_fw(struct vb2_context *ctx)
{
	vb2_error_t rv = VbExUpdateAuxFw();
	if (rv) {
		if (rv == VBERROR_EC_REBOOT_TO_RO_REQUIRED) {
			VB2_DEBUG("AUX firmware update requires RO reboot.\n");
		} else {
			VB2_DEBUG("AUX firmware update/protect failed.\n");
			request_recovery(ctx, VB2_RECOVERY_AUX_FW_UPDATE);
		}
	}
	return rv;
}

vb2_error_t ec_sync_phase2(struct vb2_context *ctx)
{
	if (!ec_sync_allowed(ctx))
		return VB2_SUCCESS;

	/* Handle updates and jumps for EC */
	vb2_error_t retval = sync_one_ec(ctx, 0);
	if (retval != VB2_SUCCESS)
		return retval;

#ifdef PD_SYNC
	/* Handle updates and jumps for PD */
	struct vb2_gbb_header *gbb = vb2_get_gbb(ctx);
	if (!(gbb->flags & VB2_GBB_FLAG_DISABLE_PD_SOFTWARE_SYNC)) {
		retval = sync_one_ec(ctx, 1);
		if (retval != VB2_SUCCESS)
			return retval;
	}
#endif

	return VB2_SUCCESS;
}

vb2_error_t ec_sync_phase3(struct vb2_context *ctx)
{
	struct vb2_shared_data *sd = vb2_get_sd(ctx);

	/* EC verification (and possibly updating / jumping) is done */
	vb2_error_t rv = VbExEcVbootDone(!!sd->recovery_reason);
	if (rv)
		return rv;

	/* Check if we need to cut-off battery. This must be done after EC
	 * firmware updating and before kernel started. */
	if (vb2_nv_get(ctx, VB2_NV_BATTERY_CUTOFF_REQUEST)) {
		VB2_DEBUG("Request to cut-off battery\n");
		vb2_nv_set(ctx, VB2_NV_BATTERY_CUTOFF_REQUEST, 0);
		/* May lose power immediately, so commit our update now. */
		vb2_nv_commit(ctx);
		VbExEcBatteryCutOff();
		return VBERROR_SHUTDOWN_REQUESTED;
	}

	return VB2_SUCCESS;
}