[thirdparty/u-boot.git] / boot / android_ab.c

// SPDX-License-Identifier: BSD-2-Clause
/*
 * Copyright (C) 2017 The Android Open Source Project
 */
#include <common.h>
#include <android_ab.h>
#include <android_bootloader_message.h>
#include <blk.h>
#include <log.h>
#include <malloc.h>
#include <part.h>
#include <memalign.h>
#include <linux/err.h>
#include <u-boot/crc.h>

/**
 * Compute the CRC-32 of the bootloader control struct.
 *
 * Only the bytes up to the crc32_le field are considered for the CRC-32
 * calculation.
 *
 * @param[in] abc bootloader control block
 *
 * Return: crc32 sum
 */
static uint32_t ab_control_compute_crc(struct bootloader_control *abc)
{
	return crc32(0, (void *)abc, offsetof(typeof(*abc), crc32_le));
}

/**
 * Initialize bootloader_control to the default value.
 *
 * It allows us to boot all slots in order from the first one. This value
 * should be used when the bootloader message is corrupted, but not when
 * a valid message indicates that all slots are unbootable.
 *
 * @param[in] abc bootloader control block
 *
 * Return: 0 on success and a negative on error
 */
static int ab_control_default(struct bootloader_control *abc)
{
	int i;
	const struct slot_metadata metadata = {
		.priority = 15,
		.tries_remaining = 7,
		.successful_boot = 0,
		.verity_corrupted = 0,
		.reserved = 0
	};

	if (!abc)
		return -EFAULT;

	memcpy(abc->slot_suffix, "a\0\0\0", 4);
	abc->magic = BOOT_CTRL_MAGIC;
	abc->version = BOOT_CTRL_VERSION;
	abc->nb_slot = NUM_SLOTS;
	memset(abc->reserved0, 0, sizeof(abc->reserved0));
	for (i = 0; i < abc->nb_slot; ++i)
		abc->slot_info[i] = metadata;

	memset(abc->reserved1, 0, sizeof(abc->reserved1));
	abc->crc32_le = ab_control_compute_crc(abc);

	return 0;
}

/**
 * Load the boot_control struct from disk into newly allocated memory.
 *
 * This function allocates and returns an integer number of disk blocks,
 * based on the block size of the passed device to help performing a
 * read-modify-write operation on the boot_control struct.
 * The boot_control struct offset (2 KiB) must be a multiple of the device
 * block size, for simplicity.
 *
 * @param[in] dev_desc Device where to read the boot_control struct from
 * @param[in] part_info Partition in 'dev_desc' where to read from, normally
 *			the "misc" partition should be used
 * @param[out] pointer to pointer to bootloader_control data
 * Return: 0 on success and a negative on error
 */
static int ab_control_create_from_disk(struct blk_desc *dev_desc,
				       const struct disk_partition *part_info,
				       struct bootloader_control **abc,
				       ulong offset)
{
	ulong abc_offset, abc_blocks, ret;

	abc_offset = offset +
		     offsetof(struct bootloader_message_ab, slot_suffix);
	if (abc_offset % part_info->blksz) {
		log_err("ANDROID: Boot control block not block aligned.\n");
		return -EINVAL;
	}
	abc_offset /= part_info->blksz;

	abc_blocks = DIV_ROUND_UP(sizeof(struct bootloader_control),
				  part_info->blksz);
	if (abc_offset + abc_blocks > part_info->size) {
		log_err("ANDROID: boot control partition too small. Need at");
		log_err(" least %lu blocks but have %lu blocks.\n",
			abc_offset + abc_blocks, part_info->size);
		return -EINVAL;
	}
	*abc = malloc_cache_aligned(abc_blocks * part_info->blksz);
	if (!*abc)
		return -ENOMEM;

	ret = blk_dread(dev_desc, part_info->start + abc_offset, abc_blocks,
			*abc);
	if (IS_ERR_VALUE(ret)) {
		log_err("ANDROID: Could not read from boot ctrl partition\n");
		free(*abc);
		return -EIO;
	}

	log_debug("ANDROID: Loaded ABC, %lu blocks\n", abc_blocks);

	return 0;
}

/**
 * Store the loaded boot_control block.
 *
 * Store back to the same location it was read from with
 * ab_control_create_from_misc().
 *
 * @param[in] dev_desc Device where we should write the boot_control struct
 * @param[in] part_info Partition on the 'dev_desc' where to write
 * @param[in] abc Pointer to the boot control struct and the extra bytes after
 *                it up to the nearest block boundary
 * Return: 0 on success and a negative on error
 */
static int ab_control_store(struct blk_desc *dev_desc,
			    const struct disk_partition *part_info,
			    struct bootloader_control *abc, ulong offset)
{
	ulong abc_offset, abc_blocks, ret;

	abc_offset = offset +
		     offsetof(struct bootloader_message_ab, slot_suffix) /
		     part_info->blksz;
	abc_blocks = DIV_ROUND_UP(sizeof(struct bootloader_control),
				  part_info->blksz);
	ret = blk_dwrite(dev_desc, part_info->start + abc_offset, abc_blocks,
			 abc);
	if (IS_ERR_VALUE(ret)) {
		log_err("ANDROID: Could not write back the misc partition\n");
		return -EIO;
	}

	return 0;
}

/**
 * Compare two slots.
 *
 * The function determines slot which is should we boot from among the two.
 *
 * @param[in] a The first bootable slot metadata
 * @param[in] b The second bootable slot metadata
 * Return: Negative if the slot "a" is better, positive of the slot "b" is
 *         better or 0 if they are equally good.
 */
static int ab_compare_slots(const struct slot_metadata *a,
			    const struct slot_metadata *b)
{
	/* Higher priority is better */
	if (a->priority != b->priority)
		return b->priority - a->priority;

	/* Higher successful_boot value is better, in case of same priority */
	if (a->successful_boot != b->successful_boot)
		return b->successful_boot - a->successful_boot;

	/* Higher tries_remaining is better to ensure round-robin */
	if (a->tries_remaining != b->tries_remaining)
		return b->tries_remaining - a->tries_remaining;

	return 0;
}

int ab_select_slot(struct blk_desc *dev_desc, struct disk_partition *part_info,
		   bool dec_tries)
{
	struct bootloader_control *abc = NULL;
	struct bootloader_control *backup_abc = NULL;
	u32 crc32_le;
	int slot, i, ret;
	bool store_needed = false;
	bool valid_backup = false;
	char slot_suffix[4];

	ret = ab_control_create_from_disk(dev_desc, part_info, &abc, 0);
	if (ret < 0) {
		/*
		 * This condition represents an actual problem with the code or
		 * the board setup, like an invalid partition information.
		 * Signal a repair mode and do not try to boot from either slot.
		 */
		return ret;
	}

	if (CONFIG_ANDROID_AB_BACKUP_OFFSET) {
		ret = ab_control_create_from_disk(dev_desc, part_info, &backup_abc,
						  CONFIG_ANDROID_AB_BACKUP_OFFSET);
		if (ret < 0) {
			free(abc);
			return ret;
		}
	}

	crc32_le = ab_control_compute_crc(abc);
	if (abc->crc32_le != crc32_le) {
		log_err("ANDROID: Invalid CRC-32 (expected %.8x, found %.8x),",
			crc32_le, abc->crc32_le);
		if (CONFIG_ANDROID_AB_BACKUP_OFFSET) {
			crc32_le = ab_control_compute_crc(backup_abc);
			if (backup_abc->crc32_le != crc32_le) {
				log_err(" ANDROID: Invalid backup CRC-32 ");
				log_err("(expected %.8x, found %.8x),",
					crc32_le, backup_abc->crc32_le);
			} else {
				valid_backup = true;
				log_info(" copying A/B metadata from backup.\n");
				memcpy(abc, backup_abc, sizeof(*abc));
			}
		}

		if (!valid_backup) {
			log_err(" re-initializing A/B metadata.\n");
			ret = ab_control_default(abc);
			if (ret < 0) {
				if (CONFIG_ANDROID_AB_BACKUP_OFFSET)
					free(backup_abc);
				free(abc);
				return -ENODATA;
			}
		}
		store_needed = true;
	}

	if (abc->magic != BOOT_CTRL_MAGIC) {
		log_err("ANDROID: Unknown A/B metadata: %.8x\n", abc->magic);
		if (CONFIG_ANDROID_AB_BACKUP_OFFSET)
			free(backup_abc);
		free(abc);
		return -ENODATA;
	}

	if (abc->version > BOOT_CTRL_VERSION) {
		log_err("ANDROID: Unsupported A/B metadata version: %.8x\n",
			abc->version);
		if (CONFIG_ANDROID_AB_BACKUP_OFFSET)
			free(backup_abc);
		free(abc);
		return -ENODATA;
	}

	/*
	 * At this point a valid boot control metadata is stored in abc,
	 * followed by other reserved data in the same block. We select a with
	 * the higher priority slot that
	 *  - is not marked as corrupted and
	 *  - either has tries_remaining > 0 or successful_boot is true.
	 * If the selected slot has a false successful_boot, we also decrement
	 * the tries_remaining until it eventually becomes unbootable because
	 * tries_remaining reaches 0. This mechanism produces a bootloader
	 * induced rollback, typically right after a failed update.
	 */

	/* Safety check: limit the number of slots. */
	if (abc->nb_slot > ARRAY_SIZE(abc->slot_info)) {
		abc->nb_slot = ARRAY_SIZE(abc->slot_info);
		store_needed = true;
	}

	slot = -1;
	for (i = 0; i < abc->nb_slot; ++i) {
		if (abc->slot_info[i].verity_corrupted ||
		    !abc->slot_info[i].tries_remaining) {
			log_debug("ANDROID: unbootable slot %d tries: %d, ",
				  i, abc->slot_info[i].tries_remaining);
			log_debug("corrupt: %d\n",
				  abc->slot_info[i].verity_corrupted);
			continue;
		}
		log_debug("ANDROID: bootable slot %d pri: %d, tries: %d, ",
			  i, abc->slot_info[i].priority,
			  abc->slot_info[i].tries_remaining);
		log_debug("corrupt: %d, successful: %d\n",
			  abc->slot_info[i].verity_corrupted,
			  abc->slot_info[i].successful_boot);

		if (slot < 0 ||
		    ab_compare_slots(&abc->slot_info[i],
				     &abc->slot_info[slot]) < 0) {
			slot = i;
		}
	}

	if (slot >= 0 && !abc->slot_info[slot].successful_boot) {
		log_err("ANDROID: Attempting slot %c, tries remaining %d\n",
			BOOT_SLOT_NAME(slot),
			abc->slot_info[slot].tries_remaining);
		if (dec_tries) {
			abc->slot_info[slot].tries_remaining--;
			store_needed = true;
		}
	}

	if (slot >= 0) {
		/*
		 * Legacy user-space requires this field to be set in the BCB.
		 * Newer releases load this slot suffix from the command line
		 * or the device tree.
		 */
		memset(slot_suffix, 0, sizeof(slot_suffix));
		slot_suffix[0] = BOOT_SLOT_NAME(slot);
		if (memcmp(abc->slot_suffix, slot_suffix,
			   sizeof(slot_suffix))) {
			memcpy(abc->slot_suffix, slot_suffix,
			       sizeof(slot_suffix));
			store_needed = true;
		}
	}

	if (store_needed) {
		abc->crc32_le = ab_control_compute_crc(abc);
		ret = ab_control_store(dev_desc, part_info, abc, 0);
		if (ret < 0) {
			if (CONFIG_ANDROID_AB_BACKUP_OFFSET)
				free(backup_abc);
			free(abc);
			return ret;
		}
	}

	if (CONFIG_ANDROID_AB_BACKUP_OFFSET) {
		/*
		 * If the backup doesn't match the primary, write the primary
		 * to the backup offset
		 */
		if (memcmp(backup_abc, abc, sizeof(*abc)) != 0) {
			ret = ab_control_store(dev_desc, part_info, abc,
					       CONFIG_ANDROID_AB_BACKUP_OFFSET);
			if (ret < 0) {
				free(backup_abc);
				free(abc);
				return ret;
			}
		}
		free(backup_abc);
	}

	free(abc);

	if (slot < 0)
		return -EINVAL;

	return slot;
}
Commit	Line	Data
d65e8da9 RT	1	// SPDX-License-Identifier: BSD-2-Clause
	2	/*
	3	* Copyright (C) 2017 The Android Open Source Project
	4	*/
d678a59d	5	#include <common.h>
d65e8da9 RT	6	#include <android_ab.h>
d65e8da9 RT	7	#include <android_bootloader_message.h>
e6f6f9e6	8	#include <blk.h>
f7ae49fc	9	#include <log.h>
336d4615	10	#include <malloc.h>
e6f6f9e6	11	#include <part.h>
d65e8da9	12	#include <memalign.h>
e6f6f9e6	13	#include <linux/err.h>
d65e8da9 RT	14	#include <u-boot/crc.h>
	15
	16	/**
	17	* Compute the CRC-32 of the bootloader control struct.
	18	*
	19	* Only the bytes up to the crc32_le field are considered for the CRC-32
	20	* calculation.
	21	*
	22	* @param[in] abc bootloader control block
	23	*
185f812c	24	* Return: crc32 sum
d65e8da9 RT	25	*/
	26	static uint32_t ab_control_compute_crc(struct bootloader_control *abc)
	27	{
	28	return crc32(0, (void )abc, offsetof(typeof(abc), crc32_le));
	29	}
	30
	31	/**
	32	* Initialize bootloader_control to the default value.
	33	*
	34	* It allows us to boot all slots in order from the first one. This value
	35	* should be used when the bootloader message is corrupted, but not when
	36	* a valid message indicates that all slots are unbootable.
	37	*
	38	* @param[in] abc bootloader control block
	39	*
185f812c	40	* Return: 0 on success and a negative on error
d65e8da9 RT	41	*/
	42	static int ab_control_default(struct bootloader_control *abc)
	43	{
	44	int i;
	45	const struct slot_metadata metadata = {
	46	.priority = 15,
	47	.tries_remaining = 7,
	48	.successful_boot = 0,
	49	.verity_corrupted = 0,
	50	.reserved = 0
	51	};
	52
	53	if (!abc)
	54	return -EFAULT;
	55
	56	memcpy(abc->slot_suffix, "a\0\0\0", 4);
	57	abc->magic = BOOT_CTRL_MAGIC;
	58	abc->version = BOOT_CTRL_VERSION;
	59	abc->nb_slot = NUM_SLOTS;
	60	memset(abc->reserved0, 0, sizeof(abc->reserved0));
	61	for (i = 0; i < abc->nb_slot; ++i)
	62	abc->slot_info[i] = metadata;
	63
	64	memset(abc->reserved1, 0, sizeof(abc->reserved1));
	65	abc->crc32_le = ab_control_compute_crc(abc);
	66
	67	return 0;
	68	}
	69
	70	/**
	71	* Load the boot_control struct from disk into newly allocated memory.
	72	*
	73	* This function allocates and returns an integer number of disk blocks,
	74	* based on the block size of the passed device to help performing a
	75	* read-modify-write operation on the boot_control struct.
	76	* The boot_control struct offset (2 KiB) must be a multiple of the device
	77	* block size, for simplicity.
	78	*
	79	* @param[in] dev_desc Device where to read the boot_control struct from
	80	* @param[in] part_info Partition in 'dev_desc' where to read from, normally
	81	* the "misc" partition should be used
	82	* @param[out] pointer to pointer to bootloader_control data
185f812c	83	* Return: 0 on success and a negative on error
d65e8da9 RT	84	*/
d65e8da9 RT	85	static int ab_control_create_from_disk(struct blk_desc *dev_desc,
0528979f	86	const struct disk_partition *part_info,
3430f24b JW	87	struct bootloader_control **abc,
3430f24b JW	88	ulong offset)
d65e8da9 RT	89	{
	90	ulong abc_offset, abc_blocks, ret;
	91
3430f24b JW	92	abc_offset = offset +
3430f24b JW	93	offsetof(struct bootloader_message_ab, slot_suffix);
d65e8da9 RT	94	if (abc_offset % part_info->blksz) {
	95	log_err("ANDROID: Boot control block not block aligned.\n");
	96	return -EINVAL;
	97	}
	98	abc_offset /= part_info->blksz;
	99
	100	abc_blocks = DIV_ROUND_UP(sizeof(struct bootloader_control),
	101	part_info->blksz);
	102	if (abc_offset + abc_blocks > part_info->size) {
	103	log_err("ANDROID: boot control partition too small. Need at");
	104	log_err(" least %lu blocks but have %lu blocks.\n",
	105	abc_offset + abc_blocks, part_info->size);
	106	return -EINVAL;
	107	}
	108	abc = malloc_cache_aligned(abc_blocks part_info->blksz);
	109	if (!*abc)
	110	return -ENOMEM;
	111
	112	ret = blk_dread(dev_desc, part_info->start + abc_offset, abc_blocks,
	113	*abc);
	114	if (IS_ERR_VALUE(ret)) {
	115	log_err("ANDROID: Could not read from boot ctrl partition\n");
	116	free(*abc);
	117	return -EIO;
	118	}
	119
	120	log_debug("ANDROID: Loaded ABC, %lu blocks\n", abc_blocks);
	121
	122	return 0;
	123	}
	124
	125	/**
	126	* Store the loaded boot_control block.
	127	*
	128	* Store back to the same location it was read from with
	129	* ab_control_create_from_misc().
	130	*
	131	* @param[in] dev_desc Device where we should write the boot_control struct
	132	* @param[in] part_info Partition on the 'dev_desc' where to write
	133	* @param[in] abc Pointer to the boot control struct and the extra bytes after
	134	* it up to the nearest block boundary
185f812c	135	* Return: 0 on success and a negative on error
d65e8da9 RT	136	*/
d65e8da9 RT	137	static int ab_control_store(struct blk_desc *dev_desc,
0528979f	138	const struct disk_partition *part_info,
3430f24b	139	struct bootloader_control *abc, ulong offset)
d65e8da9 RT	140	{
	141	ulong abc_offset, abc_blocks, ret;
	142
3430f24b JW	143	abc_offset = offset +
3430f24b JW	144	offsetof(struct bootloader_message_ab, slot_suffix) /
d65e8da9 RT	145	part_info->blksz;
	146	abc_blocks = DIV_ROUND_UP(sizeof(struct bootloader_control),
	147	part_info->blksz);
	148	ret = blk_dwrite(dev_desc, part_info->start + abc_offset, abc_blocks,
	149	abc);
	150	if (IS_ERR_VALUE(ret)) {
	151	log_err("ANDROID: Could not write back the misc partition\n");
	152	return -EIO;
	153	}
	154
	155	return 0;
	156	}
	157
	158	/**
	159	* Compare two slots.
	160	*
	161	* The function determines slot which is should we boot from among the two.
	162	*
	163	* @param[in] a The first bootable slot metadata
	164	* @param[in] b The second bootable slot metadata
185f812c	165	* Return: Negative if the slot "a" is better, positive of the slot "b" is
d65e8da9 RT	166	* better or 0 if they are equally good.
	167	*/
	168	static int ab_compare_slots(const struct slot_metadata *a,
	169	const struct slot_metadata *b)
	170	{
	171	/* Higher priority is better */
	172	if (a->priority != b->priority)
	173	return b->priority - a->priority;
	174
	175	/* Higher successful_boot value is better, in case of same priority */
	176	if (a->successful_boot != b->successful_boot)
	177	return b->successful_boot - a->successful_boot;
	178
	179	/* Higher tries_remaining is better to ensure round-robin */
	180	if (a->tries_remaining != b->tries_remaining)
	181	return b->tries_remaining - a->tries_remaining;
	182
	183	return 0;
	184	}
	185
22cdb3f0 JW	186	int ab_select_slot(struct blk_desc dev_desc, struct disk_partition part_info,
22cdb3f0 JW	187	bool dec_tries)
d65e8da9 RT	188	{
d65e8da9 RT	189	struct bootloader_control *abc = NULL;
7a0cfb87	190	struct bootloader_control *backup_abc = NULL;
d65e8da9 RT	191	u32 crc32_le;
	192	int slot, i, ret;
	193	bool store_needed = false;
7a0cfb87	194	bool valid_backup = false;
d65e8da9 RT	195	char slot_suffix[4];
d65e8da9 RT	196
3430f24b	197	ret = ab_control_create_from_disk(dev_desc, part_info, &abc, 0);
d65e8da9 RT	198	if (ret < 0) {
	199	/*
	200	* This condition represents an actual problem with the code or
	201	* the board setup, like an invalid partition information.
	202	* Signal a repair mode and do not try to boot from either slot.
	203	*/
	204	return ret;
	205	}
	206
7a0cfb87 CM	207	if (CONFIG_ANDROID_AB_BACKUP_OFFSET) {
	208	ret = ab_control_create_from_disk(dev_desc, part_info, &backup_abc,
	209	CONFIG_ANDROID_AB_BACKUP_OFFSET);
	210	if (ret < 0) {
	211	free(abc);
	212	return ret;
	213	}
3430f24b	214	}
3430f24b	215
d65e8da9 RT	216	crc32_le = ab_control_compute_crc(abc);
	217	if (abc->crc32_le != crc32_le) {
	218	log_err("ANDROID: Invalid CRC-32 (expected %.8x, found %.8x),",
	219	crc32_le, abc->crc32_le);
7a0cfb87 CM	220	if (CONFIG_ANDROID_AB_BACKUP_OFFSET) {
	221	crc32_le = ab_control_compute_crc(backup_abc);
	222	if (backup_abc->crc32_le != crc32_le) {
	223	log_err(" ANDROID: Invalid backup CRC-32 ");
	224	log_err("(expected %.8x, found %.8x),",
	225	crc32_le, backup_abc->crc32_le);
	226	} else {
	227	valid_backup = true;
	228	log_info(" copying A/B metadata from backup.\n");
	229	memcpy(abc, backup_abc, sizeof(*abc));
	230	}
	231	}
3430f24b	232
7a0cfb87 CM	233	if (!valid_backup) {
7a0cfb87 CM	234	log_err(" re-initializing A/B metadata.\n");
3430f24b JW	235	ret = ab_control_default(abc);
3430f24b JW	236	if (ret < 0) {
7a0cfb87 CM	237	if (CONFIG_ANDROID_AB_BACKUP_OFFSET)
7a0cfb87 CM	238	free(backup_abc);
3430f24b JW	239	free(abc);
	240	return -ENODATA;
	241	}
d65e8da9 RT	242	}
	243	store_needed = true;
	244	}
	245
	246	if (abc->magic != BOOT_CTRL_MAGIC) {
	247	log_err("ANDROID: Unknown A/B metadata: %.8x\n", abc->magic);
7a0cfb87 CM	248	if (CONFIG_ANDROID_AB_BACKUP_OFFSET)
7a0cfb87 CM	249	free(backup_abc);
d65e8da9 RT	250	free(abc);
	251	return -ENODATA;
	252	}
	253
	254	if (abc->version > BOOT_CTRL_VERSION) {
	255	log_err("ANDROID: Unsupported A/B metadata version: %.8x\n",
	256	abc->version);
7a0cfb87 CM	257	if (CONFIG_ANDROID_AB_BACKUP_OFFSET)
7a0cfb87 CM	258	free(backup_abc);
d65e8da9 RT	259	free(abc);
	260	return -ENODATA;
	261	}
	262
	263	/*
	264	* At this point a valid boot control metadata is stored in abc,
	265	* followed by other reserved data in the same block. We select a with
	266	* the higher priority slot that
	267	* - is not marked as corrupted and
	268	* - either has tries_remaining > 0 or successful_boot is true.
	269	* If the selected slot has a false successful_boot, we also decrement
	270	* the tries_remaining until it eventually becomes unbootable because
	271	* tries_remaining reaches 0. This mechanism produces a bootloader
	272	* induced rollback, typically right after a failed update.
	273	*/
	274
	275	/* Safety check: limit the number of slots. */
	276	if (abc->nb_slot > ARRAY_SIZE(abc->slot_info)) {
	277	abc->nb_slot = ARRAY_SIZE(abc->slot_info);
	278	store_needed = true;
	279	}
	280
	281	slot = -1;
	282	for (i = 0; i < abc->nb_slot; ++i) {
	283	if (abc->slot_info[i].verity_corrupted \|\|
	284	!abc->slot_info[i].tries_remaining) {
	285	log_debug("ANDROID: unbootable slot %d tries: %d, ",
	286	i, abc->slot_info[i].tries_remaining);
	287	log_debug("corrupt: %d\n",
	288	abc->slot_info[i].verity_corrupted);
	289	continue;
	290	}
	291	log_debug("ANDROID: bootable slot %d pri: %d, tries: %d, ",
	292	i, abc->slot_info[i].priority,
	293	abc->slot_info[i].tries_remaining);
	294	log_debug("corrupt: %d, successful: %d\n",
	295	abc->slot_info[i].verity_corrupted,
	296	abc->slot_info[i].successful_boot);
	297
	298	if (slot < 0 \|\|
	299	ab_compare_slots(&abc->slot_info[i],
	300	&abc->slot_info[slot]) < 0) {
	301	slot = i;
	302	}
	303	}
	304
	305	if (slot >= 0 && !abc->slot_info[slot].successful_boot) {
	306	log_err("ANDROID: Attempting slot %c, tries remaining %d\n",
	307	BOOT_SLOT_NAME(slot),
	308	abc->slot_info[slot].tries_remaining);
22cdb3f0 JW	309	if (dec_tries) {
	310	abc->slot_info[slot].tries_remaining--;
	311	store_needed = true;
	312	}
d65e8da9 RT	313	}
	314
	315	if (slot >= 0) {
	316	/*
	317	* Legacy user-space requires this field to be set in the BCB.
	318	* Newer releases load this slot suffix from the command line
	319	* or the device tree.
	320	*/
	321	memset(slot_suffix, 0, sizeof(slot_suffix));
	322	slot_suffix[0] = BOOT_SLOT_NAME(slot);
	323	if (memcmp(abc->slot_suffix, slot_suffix,
	324	sizeof(slot_suffix))) {
	325	memcpy(abc->slot_suffix, slot_suffix,
	326	sizeof(slot_suffix));
	327	store_needed = true;
	328	}
	329	}
	330
	331	if (store_needed) {
	332	abc->crc32_le = ab_control_compute_crc(abc);
bf2df680 AR	333	ret = ab_control_store(dev_desc, part_info, abc, 0);
bf2df680 AR	334	if (ret < 0) {
7a0cfb87 CM	335	if (CONFIG_ANDROID_AB_BACKUP_OFFSET)
7a0cfb87 CM	336	free(backup_abc);
bf2df680 AR	337	free(abc);
	338	return ret;
	339	}
d65e8da9	340	}
3430f24b	341
7a0cfb87 CM	342	if (CONFIG_ANDROID_AB_BACKUP_OFFSET) {
	343	/*
	344	* If the backup doesn't match the primary, write the primary
	345	* to the backup offset
	346	*/
	347	if (memcmp(backup_abc, abc, sizeof(*abc)) != 0) {
	348	ret = ab_control_store(dev_desc, part_info, abc,
	349	CONFIG_ANDROID_AB_BACKUP_OFFSET);
	350	if (ret < 0) {
	351	free(backup_abc);
	352	free(abc);
	353	return ret;
	354	}
bf2df680	355	}
7a0cfb87	356	free(backup_abc);
3430f24b	357	}
3430f24b	358
d65e8da9 RT	359	free(abc);
	360
	361	if (slot < 0)
	362	return -EINVAL;
	363
	364	return slot;
	365	}