linux-kernel - Re: [PATCH 5/6] x86/ptrace: down with test_thread_flag(TIF

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Date:	Tue, 14 Jun 2016 16:34:22 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Dmitry Safonov <dsafonov@...tuozzo.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Dmitry Safonov <0x7f454c46@...il.com>, khorenko@...tuozzo.com,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Cyrill Gorcunov <gorcunov@...nvz.org>, xemul@...tuozzo.com,
	X86 ML <x86@...nel.org>, Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH 5/6] x86/ptrace: down with test_thread_flag(TIF_IA32)

On 06/13, Andy Lutomirski wrote:
>
> On Mon, Jun 13, 2016 at 6:50 AM, Oleg Nesterov <oleg@...hat.com> wrote:
> >
> > Well, I can't resist but to me SA_IA32_ABI/SA_X32_ABI looks like a hack
> > too.  We actually shift TIF_*32 into k_sigaction->flags, and the fact
> > that we do this per-signal looks, well, interesting ;)
>
> Is anything actually wrong with this, though?

No, I think the patch is correct... It adds the user-visible change, but
I do not think it can break something.

Well, perhaps we should also remove SA_IA32_ABI|SA_X32_ABI from
oact->sa.sa_flags in do_sigaction() to ensure that these non-uapi flags won't
leak to user-space, but probably we do not really care.

Oleg.