[U-Boot] [PATCH v2 5/6] rename GPT partitions to detect boot failure

[Lukasz Majewski <lukma@denx.de>]

Hi Alison,

> From: Alison Chaiken <alison@she-devel.com>
> 
> This patch provides support in u-boot for renaming GPT
> partitions.  The renaming is accomplished via a new 'gpt flip'
> command which is enabled via a CONFIG_CMD_GPT_FLIP option.
> 
> The concept for the bootloader state machine is the following:
> 
> -- u-boot renames ‘primary’ partitions as ‘candidate’ and tries
>    to boot them.
> -- Linux, at boot, will rename ‘candidate’ partitions as
>    ‘primary’.
> -- If u-boot sees a ‘candidate’ partition after a boot attempt,
>    it renames it failed’ and renames the ‘backup’ partition as
>    ‘candidate’.
> 
> Logic:
> -- Partitions can go to ‘failed’ only from ‘candidate’ and only
>    via u-boot.  Partitions can go to ‘backup’ only from ‘primary’
>    and vice-versa, only via Linux.  Partitions go to ‘candidate’
>    from ‘primary’ or ‘backup’ only via u-boot.  Only system
>    update software will rename 'failed' partitions.
> 
> Rewriting the partition table has the side-effect that all partitions
> end up with "msftdata" flag set.  The reason is that partition type
> PARTITION_BASIC_DATA_GUID is hard-coded in the gpt_fill_pte()
> function.  This does not appear to cause any harm.
> 
> Signed-off-by: Alison Chaiken <alison@peloton-tech.com>
> ---
>  cmd/Kconfig    |   7 ++
>  cmd/gpt.c      | 199
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++--
> doc/README.gpt |  13 ++++ 3 files changed, 215 insertions(+), 4
> deletions(-)
> 
> diff --git a/cmd/Kconfig b/cmd/Kconfig
> index 5ee52f6..a8f7716 100644
> --- a/cmd/Kconfig
> +++ b/cmd/Kconfig
> @@ -575,6 +575,13 @@ config CMD_GPT
>  	  Enable the 'gpt' command to ready and write GPT style
> partition tables.
>  
> +config CMD_GPT_FLIP
> +	bool "GPT flip-partitions command"
> +	depends on CMD_GPT
> +	help
> +	  Enables the 'gpt' command to write modified GPT partition
> +	  tables via the 'gpt flip' command.
> +
>  config CMD_ARMFLASH
>  	#depends on FLASH_CFI_DRIVER
>  	bool "armflash"
> diff --git a/cmd/gpt.c b/cmd/gpt.c
> index c61d2b1..6a0b70f 100644
> --- a/cmd/gpt.c
> +++ b/cmd/gpt.c
> @@ -20,6 +20,7 @@
>  #include <div64.h>
>  #include <memalign.h>
>  #include <linux/compat.h>
> +#include <linux/sizes.h>
>  
>  static LIST_HEAD(disk_partitions);
>  
> @@ -190,16 +191,33 @@ static struct disk_part
> *allocate_disk_part(disk_partition_t *info, int partnum) return
> newpart; }
>  
> +static void prettyprint_part_size(char *sizestr, unsigned long
> partsize,
> +				  unsigned long blksize)
> +{
> +	unsigned long long partbytes;
> +	unsigned long partmegabytes;
> +
> +	partbytes = partsize * blksize;
> +	partmegabytes = lldiv(partbytes, SZ_1M);
> +	snprintf(sizestr, 16, "%luMiB", partmegabytes);
> +}
> +
>  static void print_gpt_info(void)
>  {
>  	struct list_head *pos;
>  	struct disk_part *curr;
> +	char partstartstr[16];
> +	char partsizestr[16];
>  
>  	list_for_each(pos, &disk_partitions) {
>  		curr = list_entry(pos, struct disk_part, list);
> +		prettyprint_part_size(partstartstr, (unsigned
> long)curr->gpt_part_info.start,
> +				      (unsigned long)
> curr->gpt_part_info.blksz);
> +		prettyprint_part_size(partsizestr, (unsigned
> long)curr->gpt_part_info.size,
> +				      (unsigned long)
> curr->gpt_part_info.blksz); +
>  		printf("Partition %d:\n", curr->partnum);
> -		printf("1st block %x, size %x\n",
> (unsigned)curr->gpt_part_info.start,
> -		       (unsigned)curr->gpt_part_info.size);
> +		printf("Start %s, size %s\n", partstartstr,
> partsizestr); printf("Block size %lu, name %s\n",
> curr->gpt_part_info.blksz, curr->gpt_part_info.name);
>  		printf("Type %s, bootable %d\n",
> curr->gpt_part_info.type, @@ -211,6 +229,85 @@ static void
> print_gpt_info(void) }
>  }
>  
> +#ifdef CONFIG_CMD_GPT_FLIP
> +static int calc_parts_list_len(int numparts)
> +{
> +	/*
> +	 * prefatory string:
> +	 * doc/README.GPT, suggests that
> +	 * int partlistlen = UUID_STR_LEN + 1 +
> strlen("partitions=uuid_disk=");
> +	 * is correct, but extract_val() expects "uuid_disk" first.
> +	 */
> +	int partlistlen = UUID_STR_LEN + 1 + strlen("uuid_disk=");
> +	/* for the comma */
> +	partlistlen++;
> +
> +	/* per-partition additions; numparts starts at 1, so this
> should be correct */
> +	partlistlen += numparts * (strlen("name=,") + PART_NAME_LEN
> + 1);
> +	/* 17 because partstr in create_gpt_partitions_list() is 16
> chars */
> +	partlistlen += numparts * (strlen("start=MiB,") + 17);
> +	partlistlen += numparts * (strlen("size=MiB,") + 17);
> +	partlistlen += numparts * (strlen("uuid=;") + UUID_STR_LEN +
> 1);
> +	/* for the terminating null */
> +	partlistlen++;
> +	debug("Length of partitions_list is %d for %d partitions\n",
> partlistlen,
> +	       numparts);
> +	return partlistlen;
> +}
> +
> +/*
> + * create the string that upstream 'gpt write' command will accept
> as an
> + * argument
> + *
> + * From doc/README.gpt, Format of partitions layout:
> + *    "partitions=uuid_disk=...;name=u-boot,size=60MiB,uuid=...;
> + *	name=kernel,size=60MiB,uuid=...;"
> + * The fields 'name' and 'size' are mandatory for every partition.
> + * The field 'start' is optional. The fields 'uuid' and 'uuid_disk'
> + * are optional if CONFIG_RANDOM_UUID is enabled.
> + */
> +static int create_gpt_partitions_list(int numparts, const char
> *guid, char *partitions_list) +{
> +	struct list_head *pos;
> +	struct disk_part *curr;
> +	char partstr[PART_NAME_LEN + 1];
> +
> +	if (!partitions_list)
> +		return -1;
> +
> +	/*
> +	 * README.gpt specifies starting with "partitions=" like so:
> +	 *      strcpy(partitions_list, "partitions=uuid_disk=");
> +	 * but that breaks extract_val, which doesn't skip over
> 'partitions='.
> +	 */
> +	strcpy(partitions_list, "uuid_disk=");
> +	strncat(partitions_list, guid, UUID_STR_LEN + 1);
> +	strcat(partitions_list, ";");
> +
> +	list_for_each(pos, &disk_partitions) {
> +		curr = list_entry(pos, struct disk_part, list);
> +		strcat(partitions_list, "name=");
> +		strncat(partitions_list, (const char
> *)curr->gpt_part_info.name, PART_NAME_LEN + 1);
> +		strcat(partitions_list, ",start=");
> +		prettyprint_part_size(partstr, (unsigned
> long)curr->gpt_part_info.start,
> +				      (unsigned long)
> curr->gpt_part_info.blksz);
> +		/* one extra byte for NULL */
> +		strncat(partitions_list, partstr, PART_NAME_LEN + 1);
> +		strcat(partitions_list, ",size=");
> +		/* lbaint_t is unsigned long, per include/ide.h */
> +		prettyprint_part_size(partstr, (unsigned
> long)curr->gpt_part_info.size,
> +				      (unsigned long)
> curr->gpt_part_info.blksz);
> +		strncat(partitions_list, partstr, PART_NAME_LEN + 1);
> +
> +		strcat(partitions_list, ",uuid=");
> +		strncat(partitions_list, (const char
> *)curr->gpt_part_info.uuid,
> +			UUID_STR_LEN + 1);
> +		strcat(partitions_list, ";");
> +	}
> +	return 0;
> +}
> +#endif
> +
>  /*
>   * read partition info into disk_partitions list where
>   * it can be printed or modified
> @@ -222,8 +319,11 @@ static int get_gpt_info(struct blk_desc
> *dev_desc) disk_partition_t info;
>  	struct disk_part *new_disk_part;
>  
> -	if (disk_partitions.next == NULL)
> -		INIT_LIST_HEAD(&disk_partitions);
> +	/*
> +	 * Always re-read partition info from device, in case
> +	 * it has changed
> +	 */
> +	INIT_LIST_HEAD(&disk_partitions);
>  
>  	for (p = 1; p <= MAX_SEARCH_PARTITIONS; p++) {
>  		ret = part_get_info(dev_desc, p, &info);
> @@ -294,6 +394,8 @@ static int set_gpt_info(struct blk_desc *dev_desc,
>  		return -1;
>  
>  	str = strdup(str_part);
> +	if (str == NULL)
> +		return -ENOMEM;
>  
>  	/* extract disk guid */
>  	s = str;
> @@ -523,6 +625,86 @@ static int do_disk_guid(struct blk_desc
> *dev_desc, char * const namestr) return 0;
>  }
>  
> +#ifdef CONFIG_CMD_GPT_FLIP
> +static int do_flip_gpt_parts(struct blk_desc *dev_desc)
> +{
> +	struct list_head *pos;
> +	struct disk_part *curr;
> +	disk_partition_t *new_partitions = NULL;
> +	char disk_guid[UUID_STR_LEN + 1];
> +	char *partitions_list, *str_disk_guid;
> +	u8 part_count = 0;
> +	int partlistlen, ret, numparts = 0;
> +
> +	ret = get_disk_guid(dev_desc, disk_guid);
> +	if (ret < 0)
> +		return ret;
> +
> +	numparts = get_gpt_info(dev_desc);
> +	if (numparts <  0)
> +		return numparts;
> +	printf("Current partition table with %d partitions is:\n",
> numparts);
> +	print_gpt_info();
> +
> +	partlistlen = calc_parts_list_len(numparts);
> +	partitions_list = (char *)malloc(partlistlen);
> +	memset(partitions_list, '\0', partlistlen);
> +
> +	ret = create_gpt_partitions_list(numparts, (const char *)
> disk_guid,
> +					 partitions_list);
> +	if (ret < 0)
> +		return ret;
> +	debug("OLD partitions_list is %s with %d chars\n",
> partitions_list, strlen(partitions_list)); +
> +	ret = set_gpt_info(dev_desc, (const char *)partitions_list,
> &str_disk_guid,
> +			   &new_partitions, &part_count);
> +	if (ret < 0)
> +		return ret;
> +
> +	list_for_each(pos, &disk_partitions) {
> +		curr = list_entry(pos, struct disk_part, list);
> +		if (!strcmp((char *)curr->gpt_part_info.name,
> "backup_kernel"))
> +			strcpy((char *)curr->gpt_part_info.name,
> "candidate_kernel");
> +		if (!strcmp((char *)curr->gpt_part_info.name,
> "primary_kernel"))
> +			strcpy((char *)curr->gpt_part_info.name,
> "backup_kernel");
> +		if (!strcmp((char *)curr->gpt_part_info.name,
> "backup_rootfs"))
> +			strcpy((char *)curr->gpt_part_info.name,
> "candidate_rootfs");
> +		if (!strcmp((char *)curr->gpt_part_info.name,
> "primary_rootfs"))
> +			strcpy((char *)curr->gpt_part_info.name,
> "backup_rootfs");
> +	}
> +
> +	ret = create_gpt_partitions_list(numparts, (const char *)
> disk_guid, partitions_list);
> +	if (ret < 0)
> +		return ret;
> +	debug("NEW partitions_list is %s with %d chars\n",
> partitions_list, strlen(partitions_list)); +
> +	ret = set_gpt_info(dev_desc, (const char *)partitions_list,
> &str_disk_guid,
> +			   &new_partitions, &part_count);
> +	if (ret < 0)
> +		return ret;
> +
> +	debug("Writing new partition table\n");
> +	ret = gpt_restore(dev_desc, disk_guid, new_partitions,
> numparts);
> +	if (ret < 0) {
> +		printf("Writing new partition table failed\n");
> +		return ret;
> +	}
> +
> +	debug("Reading back new partition table\n");
> +	numparts = get_gpt_info(dev_desc);
> +	if (numparts <  0)
> +		return numparts;
> +	printf("new partition table with %d partitions is:\n",
> numparts);
> +	print_gpt_info();
> +
> +	del_gpt_info();
> +	free(partitions_list);
> +	free(str_disk_guid);
> +	free(new_partitions);
> +	return ret;
> +}
> +#endif
> +
>  /**
>   * do_gpt(): Perform GPT operations
>   *
> @@ -567,6 +749,10 @@ static int do_gpt(cmd_tbl_t *cmdtp, int flag,
> int argc, char * const argv[]) return do_disk_guid(blk_dev_desc,
> varname); } else if (strcmp(argv[1], "read") == 0) {
>  		return do_get_gpt_info(blk_dev_desc);
> +#ifdef CONFIG_CMD_GPT_FLIP
> +	} else if (strcmp(argv[1], "flip") == 0) {
> +		return do_flip_gpt_parts(blk_dev_desc);
> +#endif
>  	} else {
>  		return CMD_RET_USAGE;
>  	}
> @@ -598,4 +784,9 @@ U_BOOT_CMD(gpt, CONFIG_SYS_MAXARGS, 1, do_gpt,
>  	" Example usage:\n"
>  	" gpt guid mmc 0\n"
>  	" gpt guid mmc 0 varname\n"
> +#ifdef CONFIG_CMD_GPT_FLIP
> +	"gpt partition-flip command\n"
> +	"gpt flip <interface> <dev>\n"
> +	"    - exchange device's 'primary' and 'backup' partition
> names\n" +#endif
>  );
> diff --git a/doc/README.gpt b/doc/README.gpt
> index c0779a4..e29b188 100644
> --- a/doc/README.gpt
> +++ b/doc/README.gpt
> @@ -210,6 +210,19 @@ Following line can be used to assess if GPT
> verification has succeed: U-BOOT> gpt verify mmc 0 $partitions
>  U-BOOT> if test $? = 0; then echo "GPT OK"; else echo "GPT ERR"; fi
>  
> +Renaming GPT partitions from U-Boot:
> +====================================
> +
> +GPT partition names are a mechanism via which userspace and U-Boot
> can +communicate about software updates and boot failure.  The 'gpt
> guid', +'gpt read' and 'gpt flip' commands facilitate programmatic
> renaming of +partitions from bootscripts by generating and modifying
> the partitions +layout string.  The code in gpt_flip() illustrates
> the case of +swapping 'primary' and 'backup' partitions via:
> +
> +U-BOOT> gpt flip mmc 0

Maybe it would be better to have 

gpt flip mmc 0 <optional parameter 'name'>

(By default we have "primary" and "backup")

In that way we could set other names to GPT partitions without the
need to modify the code.





And another request -> Could you consider adding tests for those new
gpt commands to the 'sandbox' (sandbox_defconfig) ?

Then you can 'mount' some gpt test image ('host' command) and use it
with:
gpt <command> host X .....


Despite above comments - you did a great job :-)

Reviewed-by: Lukasz Majewski <lukma@denx.de>

> +
> +Choose different partition names by modifying these strings in gpt.c.
>  
>  Partition type GUID:
>  ====================




Best regards,

Lukasz Majewski

--

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