Archive for January 15th, 2010

Getting the IP in Gcc, OSX vs. Linux

Gcc on Linux uses thunks to find the current IP address when generating PIC code.
So, while Gcc on Mac OS X might generate:
0:       call   5
5:       pop    %ebx
6:       add    $(GOT - 5),%ebx
Gcc on Linux would generate:
0:       call   16 <__i686.get_pc_thunk.bx>
5:       add    $(GOT - 5),%ebx
00000016 <__i686.get_pc_thunk.bx>:
16:       mov    (%esp),%ebx
19:       ret
Why???

Posted by dperchik on January 15th, 2010 under Uncategorized | Comment now »