From: "H. Peter Anvin" <hpa@zytor.com>
To: Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>
Cc: "security@kernel.org" <security@kernel.org>,
X86 ML <x86@kernel.org>, Borislav Petkov <bp@alien8.de>,
Sasha Levin <sasha.levin@oracle.com>,
linux-kernel@vger.kernel.org,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Jan Beulich <jbeulich@suse.com>,
xen-devel <xen-devel@lists.xen.org>,
stable@vger.kernel.org
Subject: Re: [PATCH v5 2/4] x86/ldt: Make modify_ldt synchronous
Date: Thu, 13 Aug 2015 14:05:40 -0700 [thread overview]
Message-ID: <55CD06A4.2090100@zytor.com> (raw)
In-Reply-To: <1f1e8e0367408585694132a0e8693d157959ce30.1438061139.git.luto@kernel.org>
On 07/27/2015 10:29 PM, Andy Lutomirski wrote:
> modify_ldt has questionable locking and does not synchronize
> threads. Improve it: redesign the locking and synchronize all
> threads' LDTs using an IPI on all modifications.
>
> This will dramatically slow down modify_ldt in multithreaded
> programs, but there shouldn't be any multithreaded programs that
> care about modify_ldt's performance in the first place.
>
<nitpick>
... except 32-bit programs compiled with one specific version of glibc.
Do we care? I don't think so.
</nitpick>
next prev parent reply other threads:[~2015-08-13 21:07 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-28 5:29 [PATCH v5 0/4] x86: modify_ldt improvement, test, and config option Andy Lutomirski
2015-07-28 5:29 ` [PATCH v5 1/4] x86/xen: Unmap aliases in xen_alloc_ldt and xen_free_ldt Andy Lutomirski
2015-07-28 5:29 ` [PATCH v5 2/4] x86/ldt: Make modify_ldt synchronous Andy Lutomirski
2015-07-30 7:49 ` Borislav Petkov
2015-07-30 17:56 ` Boris Ostrovsky
2015-07-30 18:14 ` Andy Lutomirski
2015-07-30 18:35 ` Boris Ostrovsky
2015-07-30 19:25 ` Andy Lutomirski
2015-07-31 16:51 ` Boris Ostrovsky
2015-08-13 21:05 ` H. Peter Anvin [this message]
2015-07-28 5:29 ` [PATCH v5 3/4] selftests/x86, x86/ldt: Add a selftest for modify_ldt Andy Lutomirski
2015-07-28 16:53 ` Kees Cook
2015-07-28 5:29 ` [PATCH v5 4/4] x86/ldt: Make modify_ldt optional Andy Lutomirski
2015-07-28 16:56 ` Kees Cook
2015-07-28 20:03 ` Willy Tarreau
2015-07-28 20:42 ` Kees Cook
2015-07-28 20:51 ` Willy Tarreau
2015-07-30 15:53 ` [PATCH v5 0/4] x86: modify_ldt improvement, test, and config option Boris Ostrovsky
2015-07-30 16:05 ` Borislav Petkov
2015-07-30 16:12 ` [Xen-devel] " Andrew Cooper
2015-07-30 16:31 ` Boris Ostrovsky
2015-07-30 17:06 ` Andrew Cooper
2015-07-30 17:18 ` Boris Ostrovsky
2015-07-31 8:43 ` Borislav Petkov
2015-07-31 13:42 ` Boris Ostrovsky
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