android_ab: Try backup booloader_message
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>
diff --git a/boot/android_ab.c b/boot/android_ab.c
index 60ae002..73b55c1 100644
--- a/boot/android_ab.c
+++ b/boot/android_ab.c
@@ -85,11 +85,13 @@
*/
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_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 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 @@
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 @@
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 @@
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)