Supporting emulated tls

[Martin Nowak]

On Mon, 19 Mar 2012 10:40:25 +0100, Jacob Carlborg <doob at me.com> wrote:

> As I understand it, in the native ELF implementation, assembly is used  
> to access the current module id, this is for FreeBSD:
>  http://people.freebsd.org/~marcel/tls.html
>  This is how ___tls_get_addr is implemented on FreeBSD ELF i386:
>   
> https://bitbucket.org/freebsd/freebsd-head/src/4e8f50fe2f05/libexec/rtld-elf/i386/reloc.c#cl-355

Not quite.
Access to the static image is done through %fs relative addressing
which is super-fast and requires no runtime linking.
The general dynamic addressing needs one tls_index
struct in the GOT for every variable and a call to  
_tls_get_addr(tls_index*).
The module index and the offset are filled by the runtime linker.