From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andrew Lutomirski <amluto@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@linux.intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Alexander van Heukelum <heukelum@fastmail.fm>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Arjan van de Ven <arjan.van.de.ven@intel.com>,
Brian Gerst <brgerst@gmail.com>,
Alexandre Julliard <julliard@winehq.com>,
Andi Kleen <andi@firstfloor.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] x86-64: espfix for 64-bit mode *PROTOTYPE*
Date: Tue, 22 Apr 2014 10:19:46 -0700 [thread overview]
Message-ID: <CA+55aFwuKTQGHzi-cFkHrkLgkS-kFptajFt4=ginxOgwDcJLrA@mail.gmail.com> (raw)
In-Reply-To: <CAObL_7EL8P0jgnjxkngqso47eFpYXHStNkvpzxSG_xCYgnaHng@mail.gmail.com>
On Tue, Apr 22, 2014 at 10:11 AM, Andrew Lutomirski <amluto@gmail.com> wrote:
>
>>
>> Anyway, if done correctly, this whole espfix should be totally free
>> for normal processes, since it should only trigger if SS is a LDT
>> entry (bit #2 set in the segment descriptor). So the normal fast-path
>> should just have a simple test for that.
>
> How? Doesn't something still need to check whether SS is funny before
> doing iret?
Just test bit #2. Don't do anything else if it's clear, because you
should be done. You don't need to do anything special if it's clear,
because I don't *think* we have any 16-bit data segments in the GDT on
x86-64.
Linus
next prev parent reply other threads:[~2014-04-22 17:19 UTC|newest]
Thread overview: 136+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-11 17:36 [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels tip-bot for H. Peter Anvin
2014-04-11 18:12 ` Andy Lutomirski
2014-04-11 18:20 ` H. Peter Anvin
2014-04-11 18:27 ` Brian Gerst
2014-04-11 18:29 ` H. Peter Anvin
2014-04-11 18:35 ` Brian Gerst
2014-04-11 21:16 ` Andy Lutomirski
2014-04-11 21:24 ` H. Peter Anvin
2014-04-11 21:53 ` Andy Lutomirski
2014-04-11 21:59 ` H. Peter Anvin
2014-04-11 22:15 ` Andy Lutomirski
2014-04-11 22:18 ` H. Peter Anvin
2014-04-13 4:20 ` H. Peter Anvin
2014-04-12 23:26 ` Alexander van Heukelum
2014-04-12 23:31 ` H. Peter Anvin
2014-04-12 23:49 ` Alexander van Heukelum
2014-04-13 0:03 ` H. Peter Anvin
2014-04-13 1:25 ` Andy Lutomirski
2014-04-13 1:29 ` Andy Lutomirski
2014-04-13 3:00 ` H. Peter Anvin
2014-04-11 21:34 ` Linus Torvalds
2014-04-11 18:41 ` Linus Torvalds
2014-04-11 18:45 ` Brian Gerst
2014-04-11 18:50 ` Linus Torvalds
2014-04-12 4:44 ` Brian Gerst
2014-04-12 17:18 ` H. Peter Anvin
2014-04-12 19:35 ` Borislav Petkov
2014-04-12 19:44 ` H. Peter Anvin
2014-04-12 20:11 ` Borislav Petkov
2014-04-12 20:34 ` Brian Gerst
2014-04-12 20:59 ` Borislav Petkov
2014-04-12 21:13 ` Brian Gerst
2014-04-12 21:40 ` Borislav Petkov
2014-04-14 7:21 ` Ingo Molnar
2014-04-14 9:44 ` Borislav Petkov
2014-04-14 9:47 ` Ingo Molnar
2014-04-12 21:53 ` Linus Torvalds
2014-04-12 22:25 ` H. Peter Anvin
2014-04-13 2:56 ` Andi Kleen
2014-04-13 3:02 ` H. Peter Anvin
2014-04-13 3:13 ` Linus Torvalds
2014-04-12 20:29 ` Brian Gerst
2014-04-14 7:48 ` Alexandre Julliard
2014-05-07 9:18 ` Sven Joachim
2014-05-07 10:18 ` Borislav Petkov
2014-05-07 16:57 ` Linus Torvalds
2014-05-07 17:09 ` H. Peter Anvin
2014-05-07 17:50 ` Alexandre Julliard
2014-05-08 6:43 ` Sven Joachim
2014-05-08 13:50 ` H. Peter Anvin
2014-05-08 20:13 ` H. Peter Anvin
2014-05-08 20:40 ` H. Peter Anvin
2014-05-12 13:16 ` Josh Boyer
2014-05-12 16:52 ` H. Peter Anvin
2014-05-14 23:43 ` [tip:x86/urgent] x86-64, modify_ldt: Make support for 16-bit segments a runtime option tip-bot for Linus Torvalds
2014-04-11 18:46 ` [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels H. Peter Anvin
2014-04-14 7:27 ` Ingo Molnar
2014-04-14 15:45 ` H. Peter Anvin
2014-04-13 2:54 ` Andi Kleen
2014-04-21 22:47 ` [PATCH] x86-64: espfix for 64-bit mode *PROTOTYPE* H. Peter Anvin
2014-04-21 23:19 ` Andrew Lutomirski
2014-04-21 23:29 ` H. Peter Anvin
2014-04-22 0:37 ` Andrew Lutomirski
2014-04-22 0:53 ` H. Peter Anvin
2014-04-22 1:06 ` Andrew Lutomirski
2014-04-22 1:14 ` H. Peter Anvin
2014-04-22 1:28 ` Andrew Lutomirski
2014-04-22 1:47 ` H. Peter Anvin
2014-04-22 1:53 ` Andrew Lutomirski
2014-04-22 11:23 ` Borislav Petkov
2014-04-22 14:46 ` Borislav Petkov
2014-04-22 16:03 ` Andrew Lutomirski
2014-04-22 16:10 ` H. Peter Anvin
2014-04-22 16:33 ` Andrew Lutomirski
2014-04-22 16:43 ` Linus Torvalds
2014-04-22 17:00 ` Andrew Lutomirski
2014-04-22 17:04 ` Linus Torvalds
2014-04-22 17:11 ` Andrew Lutomirski
2014-04-22 17:15 ` H. Peter Anvin
2014-04-23 9:54 ` One Thousand Gnomes
2014-04-23 15:53 ` H. Peter Anvin
2014-04-23 17:08 ` Andrew Lutomirski
2014-04-23 17:16 ` H. Peter Anvin
2014-04-23 17:25 ` Andrew Lutomirski
2014-04-23 17:28 ` H. Peter Anvin
2014-04-23 17:45 ` Andrew Lutomirski
2014-04-22 17:19 ` Linus Torvalds [this message]
2014-04-22 17:29 ` H. Peter Anvin
2014-04-22 17:46 ` Andrew Lutomirski
2014-04-22 17:59 ` H. Peter Anvin
2014-04-22 18:03 ` Brian Gerst
2014-04-22 18:06 ` H. Peter Anvin
2014-04-22 18:17 ` Brian Gerst
2014-04-22 18:51 ` H. Peter Anvin
2014-04-22 19:55 ` Brian Gerst
2014-04-22 20:17 ` H. Peter Anvin
2014-04-22 23:08 ` Brian Gerst
2014-04-22 23:39 ` Andi Kleen
2014-04-22 23:40 ` H. Peter Anvin
2014-04-22 17:11 ` H. Peter Anvin
2014-04-22 17:26 ` Borislav Petkov
2014-04-22 17:29 ` Andrew Lutomirski
2014-04-22 19:27 ` Borislav Petkov
2014-04-23 6:24 ` H. Peter Anvin
2014-04-23 8:57 ` Alexandre Julliard
2014-04-22 17:09 ` H. Peter Anvin
2014-04-22 17:20 ` Andrew Lutomirski
2014-04-22 17:24 ` H. Peter Anvin
2014-04-22 11:25 ` Borislav Petkov
2014-04-23 1:17 ` H. Peter Anvin
2014-04-23 1:23 ` Andrew Lutomirski
2014-04-23 1:42 ` H. Peter Anvin
2014-04-23 14:24 ` Boris Ostrovsky
2014-04-23 16:56 ` H. Peter Anvin
2014-04-28 13:04 ` Konrad Rzeszutek Wilk
2014-04-25 21:02 ` Konrad Rzeszutek Wilk
2014-04-25 21:16 ` H. Peter Anvin
2014-04-24 4:13 ` comex
2014-04-24 4:53 ` Andrew Lutomirski
2014-04-24 22:24 ` H. Peter Anvin
2014-04-24 22:31 ` Andrew Lutomirski
2014-04-24 22:37 ` H. Peter Anvin
2014-04-24 22:43 ` Andrew Lutomirski
2014-04-28 23:05 ` H. Peter Anvin
2014-04-28 23:08 ` H. Peter Anvin
2014-04-29 0:02 ` Andrew Lutomirski
2014-04-29 0:15 ` H. Peter Anvin
2014-04-29 0:20 ` Andrew Lutomirski
2014-04-29 2:38 ` H. Peter Anvin
2014-04-29 2:44 ` H. Peter Anvin
2014-04-29 3:45 ` H. Peter Anvin
2014-04-29 3:47 ` H. Peter Anvin
2014-04-29 4:36 ` H. Peter Anvin
2014-04-29 7:14 ` H. Peter Anvin
2014-04-25 12:02 ` Pavel Machek
2014-04-25 21:20 ` H. Peter Anvin
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