[U-Boot] [PATCH 3/3] rename GPT partitions to detect boot failure

Lothar Waßmann
2017-05-29T09:25:28Z

alison at peloton-tech.com wrote:

> 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.
>
> 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/gpt.c | 207 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 201 insertions(+), 6 deletions(-)
>
> diff --git a/cmd/gpt.c b/cmd/gpt.c
> index 128c895..f2c32ae 100644
> --- a/cmd/gpt.c
> +++ b/cmd/gpt.c
> @@ -21,6 +21,9 @@
> #include <memalign.h>
> #include <linux/compat.h>
>
> +/* ONEMIB is 2**20 */
> +#define ONEMIB 1024*1024
>
'()' are missing around the expression!
But anyway, there is no need to reinvent the wheel, since SZ_1M exists
in include/linux/sizes.h.

> +
> static LIST_HEAD(disk_partitions);
>
> /**
> @@ -114,7 +117,6 @@ static char *extract_val(const char *str, const char *key)
> break;
> }
> }
> -
> free(strcopy);
>
> return new;
> @@ -158,6 +160,7 @@ static void del_gpt_info(void)
> {
> struct list_head *pos = &disk_partitions;
> struct disk_part *curr;
> +
> while (!list_empty(pos)) {
> curr = list_entry(pos->next, struct disk_part, list);
> list_del(pos->next);
> @@ -165,6 +168,11 @@ static void del_gpt_info(void)
> }
> }
>
> +/*
> + * The number '33' comes from the '32' in the definition of disk_partition_t
> + * in include/part.h. That file has '37' rather than UUID_STR_LEN + 1, from
> + * include/uuid.h
> + */
> static struct disk_part *allocate_disk_part(disk_partition_t *info, int partnum)
> {
> struct disk_part *newpart;
> @@ -191,16 +199,33 @@ 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, ONEMIB);
> + 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,
> @@ -212,6 +237,89 @@ static void print_gpt_info(void)
> }
> }
>
> +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=,") + 33);
> + /* 17 because partstr below 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 ++;
>
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[16];
> +
> + 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=");
> + /*
> + * name is 32 chars long, per definition of disk_partition_t in part.h,
> + * plus one extra byte for NULL
> + */
> + strncat(partitions_list, (const char *)curr->gpt_part_info.name, 33);
>
unnecessary cast. The same holds for all the other (const char *) casts
in this patch.

> +
> + strcat(partitions_list, ",start=");
> + prettyprint_part_size(partstr, (unsigned long)curr->gpt_part_info.start,
> + (unsigned long) curr->gpt_part_info.blksz);
> + strncat(partitions_list, partstr, 17);
> +
> + 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);
> + /* one extra byte for NULL */
> + strncat(partitions_list, partstr, 17);
> +
> + strcat(partitions_list, ",uuid=");
> + strncat(partitions_list, (const char *)curr->gpt_part_info.uuid,
> + UUID_STR_LEN + 1);
> + strcat(partitions_list, ";");
> + }
> + return 0;
> +}
> +
> /*
> * read partition info into disk_partitions list where
> * it can be printed or modified
> @@ -223,8 +331,11 @@ 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);
> @@ -241,7 +352,6 @@ static int get_gpt_info(struct blk_desc *dev_desc)
> if (!valid_parts) {
> printf("** No valid partitions found **\n");
> del_gpt_info();
> - return -1;
> }
> return --valid_parts;
> }
> @@ -295,10 +405,13 @@ 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;
> val = extract_val(str, "uuid_disk");
> +
> if (!val) {
> #ifdef CONFIG_RANDOM_UUID
> *str_disk_guid = malloc(UUID_STR_LEN + 1);
> @@ -312,6 +425,7 @@ static int set_gpt_info(struct blk_desc *dev_desc,
> if (extract_env(val, &p))
> p = val;
> *str_disk_guid = strdup(p);
> +
> free(val);
> /* Move s to first partition */
> strsep(&s, ";");
> @@ -524,6 +638,83 @@ static int do_disk_guid(struct blk_desc *dev_desc, char * const namestr)
> return 0;
> }
>
> +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);
>
Useless cast.

Lothar Waßmann
--
___________________________________________________________

Ka-Ro electronics GmbH | Pascalstraße 22 | D - 52076 Aachen
Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10
Geschäftsführer: Matthias Kaussen
Handelsregistereintrag: Amtsgericht Aachen, HRB 4996

www.karo-electronics.de | info at karo-electronics.de
___________________________________________________________

--
___________________________________________________________

Ka-Ro electronics GmbH | Pascalstraße 22 | D - 52076 Aachen
Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10
Geschäftsführer: Matthias Kaussen
Handelsregistereintrag: Amtsgericht Aachen, HRB 4996

www.karo-electronics.de | info at karo-electronics.de
___________________________________________________________

--
___________________________________________________________

Ka-Ro electronics GmbH | Pascalstraße 22 | D - 52076 Aachen
Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10
Geschäftsführer: Matthias Kaussen
Handelsregistereintrag: Amtsgericht Aachen, HRB 4996

www.karo-electronics.de | info at karo-electronics.de
___________________________________________________________