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android_ab: Try backup booloader_message

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Some devices keep 2 copies of the bootloader_message in the misc
partition and write each in sequence when updating. This ensures that
there is always one valid copy of the bootloader_message. Teach u-boot
to optionally try a backup bootloader_message from a specified offset if
the primary one fails its CRC check.

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
This commit is contained in:
Joshua Watt 2023-07-03 10:07:13 -05:00 committed by Tom Rini
parent 55a4244372
commit 3430f24bc6
3 changed files with 79 additions and 11 deletions
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75
boot/android_ab.c
View file

@ -85,11 +85,13 @@ static int ab_control_default(struct bootloader_control *abc)
*/
static int ab_control_create_from_disk(struct blk_desc *dev_desc,
const struct disk_partition *part_info,
struct bootloader_control **abc)
struct bootloader_control **abc,
ulong offset)
{
ulong abc_offset, abc_blocks, ret;
abc_offset = offsetof(struct bootloader_message_ab, slot_suffix);
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;
@ -135,11 +137,12 @@ static int ab_control_create_from_disk(struct blk_desc *dev_desc,
*/
static int ab_control_store(struct blk_desc *dev_desc,
const struct disk_partition *part_info,
struct bootloader_control *abc)
struct bootloader_control *abc, ulong offset)
{
ulong abc_offset, abc_blocks, ret;
abc_offset = offsetof(struct bootloader_message_ab, slot_suffix) /
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);
@ -189,8 +192,11 @@ int ab_select_slot(struct blk_desc *dev_desc, struct disk_partition *part_info,
int slot, i, ret;
bool store_needed = false;
char slot_suffix[4];
#if ANDROID_AB_BACKUP_OFFSET
struct bootloader_control *backup_abc = NULL;
#endif
ret = ab_control_create_from_disk(dev_desc, part_info, &abc);
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
@ -200,22 +206,53 @@ int ab_select_slot(struct blk_desc *dev_desc, struct disk_partition *part_info,
return ret;
}
#if ANDROID_AB_BACKUP_OFFSET
ret = ab_control_create_from_disk(dev_desc, part_info, &backup_abc,
ANDROID_AB_BACKUP_OFFSET);
if (ret < 0) {
free(abc);
return ret;
}
#endif
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);
log_err("re-initializing A/B metadata.\n");
#if 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);
#endif
ret = ab_control_default(abc);
if (ret < 0) {
free(abc);
return -ENODATA;
log_err("re-initializing A/B metadata.\n");
ret = ab_control_default(abc);
if (ret < 0) {
#if ANDROID_AB_BACKUP_OFFSET
free(backup_abc);
#endif
free(abc);
return -ENODATA;
}
#if ANDROID_AB_BACKUP_OFFSET
} else {
/*
* Backup is valid. Copy it to the primary
*/
memcpy(abc, backup_abc, sizeof(*abc));
}
#endif
store_needed = true;
}
if (abc->magic != BOOT_CTRL_MAGIC) {
log_err("ANDROID: Unknown A/B metadata: %.8x\n", abc->magic);
#if ANDROID_AB_BACKUP_OFFSET
free(backup_abc);
#endif
free(abc);
return -ENODATA;
}
@ -223,6 +260,9 @@ int ab_select_slot(struct blk_desc *dev_desc, struct disk_partition *part_info,
if (abc->version > BOOT_CTRL_VERSION) {
log_err("ANDROID: Unsupported A/B metadata version: %.8x\n",
abc->version);
#if ANDROID_AB_BACKUP_OFFSET
free(backup_abc);
#endif
free(abc);
return -ENODATA;
}
@ -297,8 +337,21 @@ int ab_select_slot(struct blk_desc *dev_desc, struct disk_partition *part_info,
if (store_needed) {
abc->crc32_le = ab_control_compute_crc(abc);
ab_control_store(dev_desc, part_info, abc);
ab_control_store(dev_desc, part_info, abc, 0);
}
#if 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) {
ab_control_store(dev_desc, part_info, abc,
ANDROID_AB_BACKUP_OFFSET);
}
free(backup_abc);
#endif
free(abc);
if (slot < 0)

9
common/Kconfig
View file

@ -936,6 +936,15 @@ config ANDROID_AB
allows a bootloader to try a new version of the system but roll back
to previous version if the new one didn't boot all the way.
config ANDROID_AB_BACKUP_OFFSET
hex "Offset of backup bootloader control"
depends on ANDROID_AB
default 0x0
help
If non-zero, a backup bootloader message starting at this offset in
the partition will tried in the event that the primary one (starting
at offset 0) fails its checksum.
endmenu
menu "Blob list"

6
doc/android/ab.rst
View file

@ -31,6 +31,12 @@ boot script. This command analyzes and processes A/B metadata stored on a
special partition (e.g. ``misc``) and determines which slot should be used for
booting up.
If the A/B metadata partition has a backup bootloader_message block that is used
to ensure one is always valid even in the event of interruption when writing, it
can be enabled in your board configuration file::
CONFIG_ANDROID_AB_BACKUP_OFFSET=0x1000
Command usage
-------------