MySQL: list users which have been granted EXECUTE permission on a given procedure

I would like to audit my database to check which users have been granted individual EXECUTE permission to which procedure. I would like to use this information to be able to save GRANTs when changing (DROP+CREATE) the definition of some procedure in order to restore them after. How can I query the INFORMATION_SCHEMA or MYSQL schemas to retrieve that information? **Update** I'm interested in a solution working on MySQL 5.6+. For granular security, users of our datase are not granted an EXECUTE permission on the whole schema but on specific stored procedures. Answers on schema-level permissions are irrelevant.