firmware: tpm2_lite: propagate actual errors

Propagate the actual error - a non-successful response
code from the tpm or communication/serializing failure -
to the caller of the Tlcl functions in TPM 2.0 case.

Currently, the callers only have special processing for
the error codes from TCG TPM 1.2 range, which are never
returned in case of communication or serialization failures
or from the actual TPM 2.0. (The only case of mapping
TPM 2.0 error codes to TPM_E_BADINDEX is preserved in this CL.)
Thus, changing the actual values returned from the functions
won't change any current behavior in the calling layers.

This CL is a preparatory work for adding special processing
for communication errors in mount-encrypted.

BUG=chromium:702724
BRANCH=none
TEST=build; test that tpmc getvf, tpmc read still work.

Change-Id: I96b20e7285e83f0038abc01e4b7175c938867e7d
Signed-off-by: Andrey Pronin <apronin@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/977225
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>

1 files changed, 7 insertions, 7 deletions

diff --git a/firmware/include/tpm2_marshaling.h b/firmware/include/tpm2_marshaling.h
index cbfded11..3ebea388 100644
--- a/firmware/include/tpm2_marshaling.h
+++ b/firmware/include/tpm2_marshaling.h
@@ -33,18 +33,18 @@ int tpm_marshal_command(TPM_CC command, void *tpm_command_body,
  * Given a buffer received from the TPM in response to a certain command,
  * deserialize the buffer into the expeced response structure.
  *
- * struct tpm2_response is a union of all possible responses.
- *
  * @command: code of the TPM2 command for which a response is unmarshaled
  * @response_body: buffer containing the serialized response.
  * @response_size: number of bytes in the buffer containing response
+ * @response: structure to be filled with deserialized response,
+ *            struct tpm2_response is a union of all possible responses.
  *
- * Returns a pointer to the deserialized response or NULL in case of
- * unmarshaling problems.
+ * Returns 0 on success, or -1 on error.
  */
-struct tpm2_response *tpm_unmarshal_response(TPM_CC command,
-					     void *response_body,
-					     int response_size);
+int tpm_unmarshal_response(TPM_CC command,
+			   void *response_body,
+			   int response_size,
+			   struct tpm2_response *response);
 
 /**
  * tpm_get_packet_size