From: Peter Zijlstra <peterz@infradead.org>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Willy Tarreau <w@1wt.eu>,
linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de,
gnomes@lxorguk.ukuu.org.uk, torvalds@linux-foundation.org,
Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH RFC 3/4] x86/pti: don't mark the user PGD with _PAGE_NX.
Date: Mon, 8 Jan 2018 18:30:32 +0100 [thread overview]
Message-ID: <20180108173032.GD6176@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <407b4328-4447-38a5-15c1-0170741e3d14@intel.com>
On Mon, Jan 08, 2018 at 09:23:49AM -0800, Dave Hansen wrote:
> On 01/08/2018 09:17 AM, Willy Tarreau wrote:
> >> I think the prctl() should apply to an entire process, not to a thread.
> >
> > As I mentionned in another mail, I didn't know how to do it, even less
> > how to do it fast enough so that we didn't add more cycles to the syscall
> > code.
>
> You can _implement_ it with a task thread if you want. Just spray it
> across all threads at the prctl()-time instead of a single thread.
> It'll take a wee bit of locking.
>
> I just don't think the API should apply to a single thread.
It is surprisingly hard to find all tasks that share an mm. Finding all
threads in a threadgroup is easy, but we have CLONE_THREAD and CLONE_VM
as separate bits.
In any case, aside from that, setting this remotely is indeed
'intersting'.
next prev parent reply other threads:[~2018-01-08 17:30 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-08 16:12 [PATCH RFC 0/4] Per-task PTI activation Willy Tarreau
2018-01-08 16:12 ` [PATCH RFC 1/4] x86/thread_info: add TIF_NOPTI to disable PTI per task Willy Tarreau
2018-01-08 16:57 ` Thomas Gleixner
2018-01-08 17:03 ` Willy Tarreau
2018-01-08 17:14 ` Ingo Molnar
2018-01-08 16:12 ` [PATCH RFC 2/4] x86/arch_prctl: add ARCH_GET_NOPTI and ARCH_SET_NOPTI to enable/disable PTI Willy Tarreau
2018-01-08 16:49 ` Peter Zijlstra
2018-01-08 16:56 ` Willy Tarreau
2018-01-08 17:02 ` Thomas Gleixner
2018-01-08 17:10 ` Willy Tarreau
2018-01-08 17:17 ` Ingo Molnar
2018-01-08 17:26 ` Thomas Gleixner
2018-01-08 17:46 ` Ingo Molnar
2018-01-08 17:05 ` Ingo Molnar
2018-01-08 17:19 ` Peter Zijlstra
2018-01-08 17:26 ` Ingo Molnar
2018-01-08 17:50 ` Borislav Petkov
2018-01-08 17:54 ` Linus Torvalds
2018-01-08 18:22 ` Willy Tarreau
2018-01-08 20:49 ` Thomas Gleixner
2018-01-08 21:03 ` Willy Tarreau
2018-01-08 20:35 ` Willy Tarreau
2018-01-08 16:12 ` [PATCH RFC 3/4] x86/pti: don't mark the user PGD with _PAGE_NX Willy Tarreau
2018-01-08 17:03 ` Dave Hansen
2018-01-08 17:17 ` Willy Tarreau
2018-01-08 17:23 ` Dave Hansen
2018-01-08 17:30 ` Peter Zijlstra [this message]
2018-01-08 17:49 ` Willy Tarreau
2018-01-08 17:21 ` Ingo Molnar
2018-01-08 23:05 ` Andy Lutomirski
2018-01-08 23:09 ` Kees Cook
2018-01-09 4:22 ` Willy Tarreau
2018-01-08 17:05 ` Thomas Gleixner
2018-01-08 17:28 ` Dave Hansen
2018-01-08 17:50 ` Ingo Molnar
2018-01-08 18:25 ` Alan Cox
2018-01-08 18:35 ` Ingo Molnar
2018-01-08 18:35 ` Linus Torvalds
2018-01-08 18:44 ` Dave Hansen
2018-01-08 16:12 ` [PATCH RFC 4/4] x86/entry/pti: don't switch PGD on tasks holding flag TIF_NOPTI Willy Tarreau
2018-01-08 17:11 ` Ingo Molnar
2018-01-08 17:20 ` Dave Hansen
2018-01-08 18:12 ` Willy Tarreau
2018-01-08 23:01 ` Andy Lutomirski
2018-01-08 16:59 ` [PATCH RFC 0/4] Per-task PTI activation Dave Hansen
2018-01-08 17:06 ` Willy Tarreau
2018-01-08 17:17 ` Dave Hansen
2018-01-08 17:13 ` Ingo Molnar
2018-01-09 15:31 ` Eric W. Biederman
2018-01-09 16:02 ` Willy Tarreau
2018-01-09 18:11 ` Zhi Wang
2018-01-09 21:07 ` Eric W. Biederman
2018-01-09 21:57 ` Willy Tarreau
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