refactor(rmmd): plat token requests in pieces
Until now, the attestation token size was limited by the size of the
shared buffer between RMM and TF-A. With this change, RMM can now
request the token in pieces, so they fit in the shared buffer. A new
output parameter was added to the SMC call, which will return (along
with the size of bytes copied into the buffer) the number of bytes
of the token that remain to be retrieved.
TF-A will keep an offset variable that will indicate the position in
the token where the next call will retrieve bytes from. This offset
will be increased on every call by adding the number number of bytes
copied. If the received hash size is not 0, TF-A will reset the
offset to 0 and copy from that position on.
The SMC call will now return at most the size of the shared buffer
in bytes on every call. Therefore, from now on, multiple SMC calls
may be needed to be issued if the token size exceeds the shared
buffer size.
Change-Id: I591f7013d06f64e98afaf9535dbea6f815799723
Signed-off-by: Juan Pablo Conde <juanpablo.conde@arm.com>
9 files changed