asm - novice question

[Senti]

In i386.h machine description file there are 3 
lines as follows :
 

fprintf (FILE, "\tleal %sP%d@GOTOFF(%%ebx),%%edx\n", \
                
LPREFIX, (LABELNO)); \
fprintf (FILE, "\tcall *_mcount@GOT(%%ebx)\n"); \
 
1.) Can anyone help telling me what @GOTOFF(%%ebx) and @GOT(%%ebx) means 
?
2.) Or the "*" in front of _mcount .
I've built the gcc without these and i didn't 
saw anything going wild .
If someone can translate that to me or tell me where 
i can find some docs about it i would be grateful.
Thanks , Adrian