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From: "Theodore Ts'o" <tytso@mit.edu>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	w@1wt.edu, ewust@umich.edu, zakir@umich.edu, greg@kroah.com,
	mpm@selenic.com, nadiah@cs.ucsd.edu, jhalderm@umich.edu,
	tglx@linutronix.de, davem@davemloft.net, stable@vger.kernel.org,
	DJ Johnston <dj.johnston@intel.com>,
	"H. Peter Anvin" <hpa@linux.intel.com>
Subject: Re: [PATCH] random: mix in architectural randomness in extract_buf()
Date: Fri, 27 Jul 2012 22:39:38 -0400	[thread overview]
Message-ID: <20120728023938.GA3766@thunk.org> (raw)
In-Reply-To: <1343237822-7789-1-git-send-email-hpa@zytor.com>

Ok, I'll add this patch to the random tree.  I've modified the commit
message a bit since the speed advertisement of RDRAND is rather
pointless --- processes aren't generating session keys or long term
keys at a high rate, and programs can't count on /dev/random being
super fast and having unlimited entropy, since for most platforms and
even most x86 CPU's deployed in service today, this isn't true --- and
making your userspace program depond upon /dev/random in such a way
that it only works on Ivy Bridge CPU's might be good for Intel from a
vendor lock-in perspective, but it's really bad, non-portable
programming style.

Also, in the future arch_get_random_long() will almost certainly be
hooked up for other architectures, so putting an extended
advertisement for RDRAND really isn't appropriate.

					- Ted

commit d2e7c96af1e54b507ae2a6a7dd2baf588417a7e5
Author: H. Peter Anvin <hpa@linux.intel.com>
Date:   Fri Jul 27 22:26:08 2012 -0400

    random: mix in architectural randomness in extract_buf()
    
    Mix in any architectural randomness in extract_buf() instead of
    xfer_secondary_buf().  This allows us to mix in more architectural
    randomness, and it also makes xfer_secondary_buf() faster, moving a
    tiny bit of additional CPU overhead to process which is extracting the
    randomness.
    
    [ Commit description modified by tytso to remove an extended
      advertisement for the RDRAND instruction. ]
    
    Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
    Acked-by: Ingo Molnar <mingo@kernel.org>
    Cc: DJ Johnston <dj.johnston@intel.com>
    Signed-off-by: Theodore Ts'o <tytso@mit.edu>
    Cc: stable@vger.kernel.org

  parent reply	other threads:[~2012-07-28  2:39 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-07-05 18:12 [PATCH 00/10] /dev/random fixups Theodore Ts'o
2012-07-05 18:12 ` [PATCH 01/10] random: make 'add_interrupt_randomness()' do something sane Theodore Ts'o
2012-07-05 18:47   ` Matt Mackall
2012-07-05 18:52     ` Linus Torvalds
2012-07-05 21:39       ` Matt Mackall
2012-07-05 21:47         ` Linus Torvalds
2012-07-05 22:00           ` Theodore Ts'o
2012-07-05 22:21             ` Linus Torvalds
2012-07-05 22:31               ` Matt Mackall
2012-07-05 22:35                 ` Linus Torvalds
2012-07-05 23:21                 ` Theodore Ts'o
2012-07-06  2:59                   ` Linus Torvalds
2012-07-06 13:01                     ` Theodore Ts'o
2012-07-06 16:24                       ` Linus Torvalds
2012-07-06 16:52                         ` Theodore Ts'o
2012-07-09 19:15                           ` Matt Mackall
2012-07-25 18:43                         ` Thomas Gleixner
     [not found]   ` <CAGsuqq2MWuFnY7PMb_2ddBNNJr80xB_JW+Wryq3mhhmQuEojpg@mail.gmail.com>
2012-07-06 21:59     ` Theodore Ts'o
2012-07-05 18:12 ` [PATCH 02/10] random: use lockless techniques when mixing entropy pools Theodore Ts'o
2012-07-05 18:18   ` Linus Torvalds
2012-07-05 18:19   ` Greg KH
2012-07-05 23:09     ` Theodore Ts'o
2012-07-05 19:10   ` Matt Mackall
2012-07-05 19:47     ` Theodore Ts'o
2012-07-05 20:45       ` Matt Mackall
2012-07-05 18:12 ` [PATCH 03/10] random: create add_device_randomness() interface Theodore Ts'o
2012-07-05 18:12 ` [PATCH 04/10] usb: feed USB device information to the /dev/random driver Theodore Ts'o
2012-07-05 18:12 ` [PATCH 05/10] net: feed /dev/random with the MAC address when registering a device Theodore Ts'o
2012-07-05 18:12 ` [PATCH 06/10] random: use the arch-specific rng in xfer_secondary_pool Theodore Ts'o
2012-07-05 18:49   ` Linus Torvalds
2012-07-05 18:12 ` [PATCH 07/10] random: add new get_random_bytes_arch() function Theodore Ts'o
2012-07-05 18:35   ` Linus Torvalds
2012-07-05 19:50     ` Theodore Ts'o
2012-07-05 21:45     ` Matt Mackall
2012-07-25  3:37   ` H. Peter Anvin
2012-07-25  7:22     ` Ingo Molnar
2012-07-25 15:10     ` Theodore Ts'o
2012-07-25 15:19       ` H. Peter Anvin
2012-07-25 17:37       ` [PATCH] random: mix in architectural randomness in extract_buf() H. Peter Anvin
2012-07-25 23:50         ` Ben Hutchings
2012-07-26  0:32           ` H. Peter Anvin
2012-07-28  2:39         ` Theodore Ts'o [this message]
2012-07-28  2:48           ` H. Peter Anvin
2012-07-26  3:16       ` [PATCH 07/10] random: add new get_random_bytes_arch() function H. Peter Anvin
2012-07-26  3:24         ` H. Peter Anvin
2012-07-05 18:12 ` [PATCH 08/10] random: unify mix_pool_bytes() and mix_pool_bytes_entropy() Theodore Ts'o
2012-07-05 18:12 ` [PATCH 09/10] random: add tracepoints for easier debugging and verification Theodore Ts'o
2012-07-05 18:12 ` [PATCH 10/10] MAINTAINERS: Theodore Ts'o is taking over the random driver Theodore Ts'o
2012-07-06 11:40 ` [PATCH 00/10] /dev/random fixups Fengguang Wu
2012-07-06 12:44   ` Theodore Ts'o
2012-07-20 20:15 ` [PATCH] dmi: Feed DMI table to /dev/random driver Tony Luck
2012-07-20 21:03   ` Matt Mackall
2012-07-21  0:56   ` Theodore Ts'o
2012-07-21  1:19     ` Tony Luck
2012-07-21  2:02       ` Theodore Ts'o
2012-07-23 16:47         ` [PATCH] random: Add comment to random_initialize() Tony Luck

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