How to get the base addresses of segment descriptors

Hi,

Are there any ways for a user-mode program to obtain the base addresses of the segment descriptors? I have been able to get the segment limits via the "LSL" instruction, but I couldn't find any instructions to obtain the segment base address.

The Global Descriptor Table cannot be directly accessed, since it resides within the kernel memory . However, OllyDbg does be able to display the segment information in the register window. Therefore, I guess the segment base addresses should be accessible from User Mode applications. Can anyone provide any suggestions?

Thanks,