Re: [PATCH v4 2/7] x86/fsgsbase/64: Make ptrace read FS/GS base accurately

[Thomas Gleixner]

On Wed, 20 Jun 2018, Chang S. Bae wrote:

> From: Andy Lutomirski <luto@xxxxxxxxxx>
> 
> ptrace can read FS/GS base using the register access API
> (PTRACE_PEEKUSER, etc) or PTRACE_ARCH_PRCTL.  Make both of these
> mechanisms return the actual FS/GS base.

That's the 'BUG' fix, right? Ok, not something which needs to be urgently
backported it seems. It's surely a correctness issue, which improved
debugability, but surely not something crucial.

So the right ordering of the patches is:

   1) Introduce task_seg_base() as a standalong patch w/o using it.

   2) Add the new fsgs helpers and use task_seg_base() right away instead
      of adding this misleading 'preserve bug' comment just to remove it
      one patch later.

   .....

Thanks,

	tglx