Add powerfail during final sector erase #354
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jpbland1
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danielinux
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Sep 7, 2023
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investigate a way to avoid erasing the key until wolfBoot_success |
the problems of losing the encryption key when the power fails before the key can be written back, failing to select the correct NVM_FLASH_WRITEONCE sector when a sector is corrupt, and losing the testing state when the power fails before the partition state can be set. these issues are addressed in the next commit
repeatable steps so that power failure wont erase the encryption key and wont cause skipping the testing phase of boot. this is done by marking the update partition as final swap when erasing the final sector and backing up the key in boot sector 0 after swaping the real boot sector 0 to swap. then when a power failure occurs the encryption key will be available in either boot sector 0 or the normal location. the intermediate phase also prevents skipping the testing phase since the last sector, which holds the boot state, is erased and then set repeatably, since the final swap state is set on the update partition
leave the encryption key for wolfBoot_success to erase. FINAL_SWAP was also stopping the case where the partition was put into testing before the update sector status flags could be erased. now, don't erase the update sector flags. instead put the update partition in IMG_STATE_FINAL_FLAGS state before putting the boot partition in IMG_STATE_TESTING. Then only erase the update sector flags on wolfBoot_update_trigger. under this scheme, the sector flags are intact if the power failed before we could set IMG_STATE_TESTING but are wiped if we do need to swap over after after wolfBoot_success fails to be called
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NVM_FLASH_WRITEONCE can powerfail after FLAGS_FINAL and TESTING partition states have been set
danielinux
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danielinux
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Oct 13, 2023
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Add powerfail during final sector erase, exposing the problems of losing the encryption key when the power fails before the key can be written back, failing to select the correct NVM_FLASH_WRITEONCE sector when a sector is corrupt, and losing the testing state when the power fails before the partition state can be set. these issues are addressed in the next commit
ZD 15415