Re: [PATCH v3 2/7] x86/arch_prctl: Fix ARCH_GET_FS and ARCH_GET_GS

[Ingo Molnar]

* Andy Lutomirski <luto@xxxxxxxxxx> wrote:

> ARCH_GET_FS and ARCH_GET_GS attempted to figure out the fsbase and
> gsbase respectively from saved thread state.  This was wrong: fsbase
> and gsbase live in registers while a thread is running, not in
> memory.

So I'm wondering, the current code looks totally broken,what user-space code can 
possibly use this? I checked glibc and Wine, and neither of them does. Wine uses 
ARCH_SET_GS and glibc uses ARCH_SET_FS, but that's all - neither actually tries to 
use the ARCH_GET_* reading APIs.

So for backporting purposes I'd be much happier about simply returning -EINVAL or 
-ENOSYS, and we could re-introduce this code in v4.7.

Thanks,

	Ingo