From: "H. Peter Anvin" <hpa@zytor.com>
To: Andrew Lutomirski <amluto@gmail.com>
Cc: "H. Peter Anvin" <hpa@linux.intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.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>,
Borislav Petkov <bp@alien8.de>,
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: Mon, 21 Apr 2014 18:14:54 -0700 [thread overview]
Message-ID: <a035392c-f332-4b3f-b851-13b0c7a0fc68@email.android.com> (raw)
In-Reply-To: <CAObL_7FUDpV9md+UnDbXxWw=trrXLFLNNJMNegdezrQt7rm6TA@mail.gmail.com>
I wanted to avoid the "another cpu made this allocation, now I have to free" crap, but I also didn't want to grab the lock if there was no work needed.
On April 21, 2014 6:06:19 PM PDT, Andrew Lutomirski <amluto@gmail.com> wrote:
>On Mon, Apr 21, 2014 at 5:53 PM, H. Peter Anvin <hpa@zytor.com> wrote:
>> Well, if 2^17 CPUs are allocated we might 2K pages allocated. We
>could easily do a bitmap here, of course. NR_CPUS/64 is a small
>number, and would reduce the code complexity.
>>
>
>Even simpler: just get rid of the check entirely. That is, break out
>of the higher level loops once one of them is set (this should be a
>big speedup regardless) and don't allocate the page if the first PTE
>is already pointing at something.
>
>After all, espfix_already_there is mostly a duplicate of
>init_espfix_cpu.
>
>--Andy
--
Sent from my mobile phone. Please pardon brevity and lack of formatting.
next prev parent reply other threads:[~2014-04-22 1:15 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 [this message]
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
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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