Re: Getting offset of inital-exec TLS variables on GNU/Linux

[Florian Weimer <fweimer@redhat.com>]

* Simon Marchi:

> On 2019-05-17 6:21 a.m., Florian Weimer wrote:
>> Is it possible to obtain the offset of initial-exec TLS variable on
>> GNU/Linux?
>> 
>> It doesn't seem so because GDB executes the DWARF to access the TLS
>> variable, so the offset is an implementation detail.  Although it is
>> often visible at the ELF layer.
>> 
>> Thanks,
>> Florian
>
> Can you clarify a little bit?
>
> You are looking for the offset the variable from which point of reference:
>
> - The start of the TLS area of this module?
> - The start of the TLS area of the current thread?

The offset from something related to the thread pointer to the variable,
for cases where this is constant (specifically, initial-exec TLS
variables).

> Also, are you looking for something you can find statically, with just the
> executable, or are you working in the context of the live process?

I have a live process, and it would be best if the information matched
that process (even if it uses different libraries than those currently
installed in the file system).

Thanks,
Florian