IDC: fix message cache handling

When an IDC message is received from another core, the receiver core
doesn't have any useful data for it in cache. Writing back the cache
can corrupt the message data. Cache has to be invalidated instead.

Signed-off-by: Guennadi Liakhovetski <[email protected]>

src/idc/zephyr_idc.c

@@ -63,7 +63,8 @@ static void idc_handler(struct k_p4wq_work *work)
 	int payload = -1;
 	k_spinlock_key_t key;
 
-	sys_cache_data_flush_range(msg, sizeof(*msg));
+	/* A message is received from another core, invalidate local cache */
+	sys_cache_data_invd_range(msg, sizeof(*msg));
 
 	if (msg->size == sizeof(int)) {
 		const int idc_handler_memcpy_err __unused =
@@ -123,12 +124,14 @@ int idc_send_msg(struct idc_msg *msg, uint32_t mode)
 					       msg->payload, msg->size);
 		assert(!idc_send_memcpy_err);
 
+		/* Sending a message to another core, write back local payload cache */
 		sys_cache_data_flush_range(payload->data, MIN(sizeof(payload->data), msg->size));
 	}
 
 	/* Temporarily store sender core ID */
 	msg_cp->core = cpu_get_id();
 
+	/* Sending a message to another core, write back local message cache */
 	sys_cache_data_flush_range(msg_cp, sizeof(*msg_cp));
 	k_p4wq_submit(q_zephyr_idc + target_cpu, work);