Linux doesn’t have (AFAIK) an open-source equivalent to IDA Pro, although there is a nice graphic debugger for i386/amd64 called EDB
Fortunately you can disassemble your binary manually using free and open source GNU tools as explained here:
http://chdk.wikia.com/wiki/GPL_Disassembling
Update: There is also Bokken disassembler interface: http://inguma.eu/projects/bokken Thanks Antonio Ospite for show me it!