From: Borislav Petkov <bp@alien8.de>
To: Ingo Molnar <mingo@kernel.org>
Cc: Hector Marco-Gisbert <hecmargi@upv.es>,
linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Alexander Viro <viro@zeniv.linux.org.uk>,
Jan-Simon <dl9pf@gmx.de>,
linux-fsdevel@vger.kernel.org, kees Cook <keescook@chromium.org>,
Ismael Ripoll <iripoll@disca.upv.es>
Subject: Re: [PATCH] mm/x86: AMD Bulldozer ASLR fix
Date: Fri, 27 Mar 2015 13:35:38 +0100 [thread overview]
Message-ID: <20150327123537.GB18912@pd.tnic> (raw)
In-Reply-To: <20150327121448.GB15631@gmail.com>
On Fri, Mar 27, 2015 at 01:14:48PM +0100, Ingo Molnar wrote:
> It's not a bug, it's a feature: to work around a Bulldozer cache
> aliasing performance problem we have to keep bits 12,13,14 equal for
> all mappings in the system.
>
> Your patch improves upon that fix: by per-boot randomizing the
> constant portion of the randomized range.
I have this one on the TODO list for today, I'll take care of those
formulations when applying.
> Btw., does anyone know how relevant the performance fix is these days?
> A simpler improvement would be to remove the workaround altogether and
> recover proper randomization of bits 12,13,14.
Nothing has changed with that respect in F15h, i.e. Bulldozer uarch. I
think we still need this workaround in place.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
--
next prev parent reply other threads:[~2015-03-27 12:37 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-24 18:00 Hector Marco-Gisbert
2015-03-24 19:15 ` Borislav Petkov
2015-03-25 18:29 ` Hector Marco
2015-03-25 18:36 ` Hector Marco-Gisbert
2015-03-26 19:08 ` Borislav Petkov
2015-03-27 11:38 ` Hector Marco-Gisbert
2015-03-27 12:14 ` Ingo Molnar
2015-03-27 12:35 ` Borislav Petkov [this message]
2015-03-27 14:44 ` Borislav Petkov
2015-03-27 15:06 ` Hector Marco-Gisbert
2015-03-28 13:10 ` Kees Cook
2015-03-29 8:51 ` Ingo Molnar
2015-03-29 9:53 ` Borislav Petkov
2015-03-31 7:59 ` Ingo Molnar
2015-03-31 12:37 ` [tip:x86/mm] x86/mm: Improve AMD Bulldozer ASLR workaround tip-bot for Hector Marco-Gisbert
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