Re: [PATCH 7/7] clone3: ensure copy_thread_tls is implemented

From: Christian Brauner
Date: Thu Jan 02 2020 - 13:09:10 EST

On Thu, Jan 02, 2020 at 06:24:13PM +0100, Amanieu d'Antras wrote:
> copy_thread implementations handle CLONE_SETTLS by reading the TLS
> value from the registers containing the syscall arguments for
> clone. This doesn't work with clone3 since the TLS value is passed
> in clone_args instead.
> Signed-off-by: Amanieu d'Antras <amanieu@xxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # 5.3.x

I'm in favor of this change. But we need to make sure that any arch
which now has ARCH_WANTS_SYS_CLONE3 set but doesn't implement
copy_thread_tls() is fixed.

Once all architectures have clone3() support - and there are
just a few by now (IA64 comes to mind) this means we should also be able
to get rid of of copy_thread() completely. That seems desirable to me as
it makes the codepaths easier to follow.

Reviewed-by: Christian Brauner <christian.brauner@xxxxxxxxxx>