Efficient Ways of Verifying ROM Code?

Hello !

Is there an efficient way of verifying the ROM - firmware code ?

Have a scenario where a block A executes some instructions loaded up into its ROM using backdoor process.

a. Is it ok to load up the same .hex content into our checkers and verify the output generated by block A against the ROM content read inside the checker ?

Is there an efficient way to validate the same? Share in your inputs.