This patch allows the ramoops to read previous logs from an
AES encrypted location while still allowing writes to the
current log.
This is used to allow the backing store to be encrypted and
then written to disk by the bootloader. The keys to decrypt
are loaded by userspace and then pstore is remounted to
force a reload of the now decrypted backing store.
4ddab9af ANDROID: fs/pstore/ramoops: Use vmalloc() for old buffer
f122f327 fs/pstore/ramoops: Allocate decryption buffer with vmalloc
2b946394 fs/pstore: Don't reset update flag until close and use io memcpy
b71d0123 fs/pstore/ramoops: add alternate encrypted buffer support
Bug: 128936886
Bug: 141911711
Test: Encrypt and decrypt ramoops successfully
Change-Id: I84bdaa01d54b2ba6c06686726bbdcf90da49042e
Signed-off-by: Chungjui Fan <chungjuifan@google.com>
b1383d2f9f