The backup offset is in bytes, but was incorrectly be interpreted as
blocks, leading to it being written to the wrong location. Fix the
calculation, clarify that ANDROID_AB_BACKUP_OFFSET is in bytes and must
be a multiple of the block size, and add a runtime check to validate the
offset.
Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Fixes: 3430f24bc69d ("android_ab: Try backup booloader_message")
Link: https://lore.kernel.org/r/20240828143924.3987331-1-JPEWhacker@gmail.com
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
cc2f60c13f