| 摘要 |
A data processing apparatus comprises a processing element having associated memory storage and one or more registers, the processing element being configured to perform processing activities in two or more security modes so as to inhibit a processing activity performed in one of the security modes from accessing at least some information associated with a processing activity performed in another of the security modes; in which the processing element is configured, in response to a function call causing a branch from a processing activity in a first security mode to a processing activity in a second security mode, to store the contents of one or more of the registers in the memory storage and, in response to a branch return to the first security mode, to retrieve the register contents from the memory storage; and trace apparatus configured to generate items of trace data indicative of processing activities of the processing element; in which the trace apparatus is configured to detect a branch return operation by the processing element and to generate one or more items of trace data relating to the branch return operation; and in which the trace apparatus is configured to detect the processing element retrieving register contents from the memory storage in response to a branch return to the first security mode and to generate one or more further items of trace data relating to the retrieval of the register contents from the memory storage. |
