crypto: inside-secure - Prevent missing of processing errors

On systems with coherence issues, packet processed could succeed while
it should have failed, e.g. because of an authentication fail.
This is because the driver would read stale status information that had
all error bits initialised to zero = no error.
Since this is potential a security risk, we want to prevent it from being
a possibility at all. So initialize all error bits to error state, so
that reading stale status information will always result in errors.
Signed-off-by: Pascal van Leeuwen <pvanleeuwen@rambus.com>
Acked-by: Antoine Tenart <antoine.tenart@bootlin.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/inside-secure/safexcel_ring.c

@@ -236,8 +236,8 @@ struct safexcel_result_desc *safexcel_add_rdesc(struct safexcel_crypto_priv *pri
 
 	rdesc->particle_size = len;
 	rdesc->rsvd0 = 0;
-	rdesc->descriptor_overflow = 0;
-	rdesc->buffer_overflow = 0;
+	rdesc->descriptor_overflow = 1; /* assume error */
+	rdesc->buffer_overflow = 1;     /* assume error */
 	rdesc->last_seg = last;
 	rdesc->first_seg = first;
 	rdesc->result_size = EIP197_RD64_RESULT_SIZE;
@@ -245,9 +245,10 @@ struct safexcel_result_desc *safexcel_add_rdesc(struct safexcel_crypto_priv *pri
 	rdesc->data_lo = lower_32_bits(data);
 	rdesc->data_hi = upper_32_bits(data);
 
-	/* Clear length & error code in result token */
+	/* Clear length in result token */
 	rtoken->packet_length = 0;
-	rtoken->error_code = 0;
+	/* Assume errors - HW will clear if not the case */
+	rtoken->error_code = 0x7fff;
 
 	return rdesc;
 }