More on %gs:0x0

[Amittai Aviram]

Here is a follow-up to my previous query.  My question remains this:   
how do values get into %gs:0x0?  Suppose I have a simple C program  
called prog, with source prog.c.  Suppose I perform the following steps:

gcc -Wall -static -o prog prog.c

objdump -D prog > prog_obj.txt

grep "%gs:0x0" prog_obj.txt | more

The final step will show me zillions of instances of moving data from  
location %gs:0x0 to a general purpose register, but not a single  
instance of moving data _into_ location %gs:0x0.  How does anything  
except 0 ever get into %gs:0x0?  This is a glibc question because all  
the routines that have these instructions and depend on them are glibc  
routines.  Thanks!





Amittai Aviram
Graduate Student in Computer Science
Yale University
646 483 2639
amittai.aviram@yale.edu
http://www.amittai.com