linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Tony Luck <tony.luck@gmail.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	kernel-hardening@lists.openwall.com,
	Peter Zijlstra <peterz@infradead.org>,
	Alan Cox <alan.cox@intel.com>, Will Deacon <will.deacon@arm.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Solomon Peachy <pizza@shaftnet.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Christian Lamparter <chunkeey@googlemail.com>,
	Elena Reshetova <elena.reshetova@intel.com>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	Andi Kleen <ak@linux.intel.com>,
	"James E.J. Bottomley" <jejb@linux.vnet.ibm.com>,
	Linux SCSI List <linux-scsi@vger.kernel.org>,
	Jonathan Corbet <corbet@lwn.net>,
	"the arch/x86 maintainers" <x86@kernel.org>,
	Russell King <linux@armlinux.org.uk>,
	Ingo Molnar <mingo@redhat.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
	Linux Media Mailing List <linux-media@vger.kernel.org>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Kees Cook <keescook@chromium.org>, Jan Kara <jack@suse.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	qla2xxx-upstream@qlogic.com, Thomas Gleixner <tglx@linutronix.de>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Kalle Valo <kvalo@codeaurora.org>,
	Alan Cox <alan@linux.intel.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	Greg KH <gregkh@linuxfoundation.org>,
	Linux Wireless List <linux-wireless@vger.kernel.org>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Network Development <netdev@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"David S. Miller" <davem@davemloft.net>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Subject: Re: [PATCH v2 00/19] prevent bounds-check bypass via speculative execution
Date: Tue, 16 Jan 2018 11:21:19 -0800	[thread overview]
Message-ID: <CA+8MBbL-ZJhTT7jTKVffS5r_7Qq6b-Af96YiNLrMs7Ndo45WhA@mail.gmail.com> (raw)
In-Reply-To: <CA+55aFwUspY8DG3hRxZqQaf_n_0OZxGCd=pELc8ZVuBu+058cA@mail.gmail.com>

On Sat, Jan 13, 2018 at 10:51 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
> On Fri, Jan 12, 2018 at 4:15 PM, Tony Luck <tony.luck@gmail.com> wrote:
> So your argument depends on "the uarch will actually run the code in
> order if there are no events that block the pipeline".

And might be bogus ... I'm a software person not a u-arch expert. That
sounded good in my head, but the level of parallelism may be greater
than I can imagine.

> Or at least it depends on a certain latency of the killing of any OoO
> execution being low enough that the cache access doesn't even begin.
>
> I realize that that is very much a particular microarchitectural
> detail, but it's actually a *big* deal. Do we have a set of rules for
> what is not a worry, simply because the speculated accesses get killed
> early enough?
>
> Apparently "test a register value against a constant" is good enough,
> assuming that register is also needed for the address of the access.

People who do understand this are working on what can be guaranteed.
For now don't make big plans based on my ramblings.

-Tony

  reply	other threads:[~2018-01-16 19:21 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-12  0:46 [PATCH v2 00/19] prevent bounds-check bypass via speculative execution Dan Williams
2018-01-12  0:46 ` [PATCH v2 01/19] Documentation: document array_ptr Dan Williams
2018-01-12 10:38   ` Geert Uytterhoeven
2018-01-16 21:01   ` Kees Cook
2018-01-12  0:46 ` [PATCH v2 02/19] arm64: implement ifence_array_ptr() Dan Williams
2018-01-12  0:46 ` [PATCH v2 03/19] arm: " Dan Williams
2018-01-12  0:46 ` [PATCH v2 04/19] x86: implement ifence() Dan Williams
2018-01-12  2:27   ` Eric W. Biederman
2018-01-12  3:39     ` Dan Williams
2018-01-12  0:46 ` [PATCH v2 05/19] x86: implement ifence_array_ptr() and array_ptr_mask() Dan Williams
2018-01-12  0:46 ` [PATCH v2 06/19] asm-generic/barrier: mask speculative execution flows Dan Williams
2018-01-12  2:42   ` Eric W. Biederman
2018-01-12  9:12   ` Peter Zijlstra
2018-01-13  0:41     ` Dan Williams
2018-01-15  8:46       ` Peter Zijlstra
2018-01-12  0:47 ` [PATCH v2 07/19] x86: introduce __uaccess_begin_nospec and ASM_IFENCE Dan Williams
2018-01-12 17:51   ` Josh Poimboeuf
2018-01-12 18:21     ` Dan Williams
2018-01-12 18:58       ` Josh Poimboeuf
2018-01-12 19:26         ` Dan Williams
2018-01-12 20:01           ` Linus Torvalds
2018-01-12 20:41             ` Josh Poimboeuf
2018-01-12  0:47 ` [PATCH v2 08/19] x86: use __uaccess_begin_nospec and ASM_IFENCE in get_user paths Dan Williams
2018-01-12  1:11   ` Linus Torvalds
2018-01-12  1:14     ` Dan Williams
2018-01-12  0:47 ` [PATCH v2 09/19] ipv6: prevent bounds-check bypass via speculative execution Dan Williams
2018-01-12  0:47 ` [PATCH v2 10/19] ipv4: " Dan Williams
2018-01-12  7:59   ` Greg KH
2018-01-12 18:47     ` Dan Williams
2018-01-13  8:56       ` Greg KH
2018-01-12  0:47 ` [PATCH v2 11/19] vfs, fdtable: " Dan Williams
2018-01-12  0:47 ` [PATCH v2 12/19] userns: " Dan Williams
2018-01-12  0:47 ` [PATCH v2 13/19] udf: " Dan Williams
2018-01-15 10:32   ` Jan Kara
2018-01-15 17:49     ` Dan Williams
2018-01-12  0:47 ` [PATCH v2 14/19] [media] uvcvideo: " Dan Williams
2018-08-06 21:40   ` Laurent Pinchart
2018-01-12  0:47 ` [PATCH v2 15/19] carl9170: " Dan Williams
2018-01-12 14:42   ` Christian Lamparter
2018-01-12 18:39     ` Dan Williams
2018-01-12 20:01       ` Christian Lamparter
2018-01-12 23:05         ` Dan Williams
2018-01-12  0:47 ` [PATCH v2 16/19] p54: " Dan Williams
2018-01-12  0:47 ` [PATCH v2 17/19] qla2xxx: " Dan Williams
2018-01-12  1:19   ` James Bottomley
2018-01-12  5:38     ` Dan Williams
2018-01-12  6:05       ` James Bottomley
2018-01-12  0:48 ` [PATCH v2 18/19] cw1200: " Dan Williams
2018-01-12  0:48 ` [PATCH v2 19/19] net: mpls: " Dan Williams
2018-01-12  1:19 ` [PATCH v2 00/19] " Linus Torvalds
2018-01-12  1:41   ` Dan Williams
2018-01-18 13:18     ` Will Deacon
2018-01-18 16:58       ` Dan Williams
2018-01-18 17:05         ` Will Deacon
2018-01-18 21:41           ` Laurent Pinchart
2018-01-13  0:15   ` Tony Luck
2018-01-13 18:51     ` Linus Torvalds
2018-01-16 19:21       ` Tony Luck [this message]
2018-01-12 10:02 ` Russell King - ARM Linux

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CA+8MBbL-ZJhTT7jTKVffS5r_7Qq6b-Af96YiNLrMs7Ndo45WhA@mail.gmail.com \
    --to=tony.luck@gmail.com \
    --cc=ak@linux.intel.com \
    --cc=akpm@linux-foundation.org \
    --cc=alan.cox@intel.com \
    --cc=alan@linux.intel.com \
    --cc=ast@kernel.org \
    --cc=catalin.marinas@arm.com \
    --cc=chunkeey@googlemail.com \
    --cc=corbet@lwn.net \
    --cc=dan.j.williams@intel.com \
    --cc=davem@davemloft.net \
    --cc=ebiederm@xmission.com \
    --cc=elena.reshetova@intel.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=hpa@zytor.com \
    --cc=jack@suse.com \
    --cc=jejb@linux.vnet.ibm.com \
    --cc=keescook@chromium.org \
    --cc=kernel-hardening@lists.openwall.com \
    --cc=kuznet@ms2.inr.ac.ru \
    --cc=kvalo@codeaurora.org \
    --cc=laurent.pinchart@ideasonboard.com \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-media@vger.kernel.org \
    --cc=linux-scsi@vger.kernel.org \
    --cc=linux-wireless@vger.kernel.org \
    --cc=linux@armlinux.org.uk \
    --cc=mark.rutland@arm.com \
    --cc=martin.petersen@oracle.com \
    --cc=mchehab@kernel.org \
    --cc=mingo@redhat.com \
    --cc=netdev@vger.kernel.org \
    --cc=peterz@infradead.org \
    --cc=pizza@shaftnet.org \
    --cc=qla2xxx-upstream@qlogic.com \
    --cc=tglx@linutronix.de \
    --cc=thomas.lendacky@amd.com \
    --cc=torvalds@linux-foundation.org \
    --cc=viro@zeniv.linux.org.uk \
    --cc=will.deacon@arm.com \
    --cc=x86@kernel.org \
    --cc=yoshfuji@linux-ipv6.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).