From: "H. Peter Anvin" <hpa@zytor.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
Andi Kleen <andi@firstfloor.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
Steven Rostedt <srostedt@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
David Miller <davem@davemloft.net>,
Roland McGrath <roland@redhat.com>,
Ulrich Drepper <drepper@redhat.com>,
Rusty Russell <rusty@rustcorp.com.au>,
Gregory Haskins <ghaskins@novell.com>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
"Luis Claudio R. Goncalves" <lclaudio@uudg.org>,
Clark Williams <williams@redhat.com>,
Christoph Lameter <cl@linux-foundation.org>
Subject: Re: [RFC PATCH] x86 alternatives : fix LOCK_PREFIX race with preemptible kernel and CPU hotplug
Date: Thu, 14 Aug 2008 11:37:55 -0700 [thread overview]
Message-ID: <48A47B83.3090408@zytor.com> (raw)
In-Reply-To: <48A46EC2.1010301@goop.org>
Jeremy Fitzhardinge wrote:
>
> Ah, OK. I'd thought we started unlocked, but given that I've just been
> disassembling the kernel and looking at the lock prefixes, that's a bit
> of a braino on my part.
>
> BTW, using the ds prefix allows us to undo the hack of dealing with
> locked instructions with exception handlers. There was a bug where if
> we do lock->nop, then the address of a faulting instruction changes, so
> we need exception records for both the locked and unlocked forms. Using
> ds means the instruction size doesn't change, so we only need one
> exception record. I don't remember off hand where that happens.
>
Using %ds: rather than nop really seems to solve a whole lot of
problems, and might even be faster to boot. It really sounds like a
no-brainer.
-hpa
next prev parent reply other threads:[~2008-08-14 18:46 UTC|newest]
Thread overview: 100+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-08-07 18:20 [PATCH 0/5] ftrace: to kill a daemon Steven Rostedt
2008-08-07 18:20 ` [PATCH 1/5] ftrace: create __mcount_loc section Steven Rostedt
2008-08-07 18:20 ` [PATCH 2/5] ftrace: mcount call site on boot nops core Steven Rostedt
2008-08-07 18:20 ` [PATCH 3/5] ftrace: enable mcount recording for modules Steven Rostedt
2008-08-08 6:43 ` Rusty Russell
2008-08-08 12:51 ` Steven Rostedt
2008-08-07 18:20 ` [PATCH 4/5] ftrace: rebuild everything on change to FTRACE_MCOUNT_RECORD Steven Rostedt
2008-08-07 18:20 ` [PATCH 5/5] ftrace: enable using mcount recording on x86 Steven Rostedt
2008-08-07 18:47 ` [PATCH 0/5] ftrace: to kill a daemon Mathieu Desnoyers
2008-08-07 20:42 ` Steven Rostedt
2008-08-08 17:22 ` Mathieu Desnoyers
2008-08-08 17:36 ` Steven Rostedt
2008-08-08 17:46 ` Mathieu Desnoyers
2008-08-08 18:13 ` Steven Rostedt
2008-08-08 18:15 ` Peter Zijlstra
2008-08-08 18:21 ` Mathieu Desnoyers
2008-08-08 18:41 ` Steven Rostedt
2008-08-08 19:04 ` Linus Torvalds
2008-08-08 19:05 ` Mathieu Desnoyers
2008-08-08 23:38 ` Steven Rostedt
2008-08-09 0:23 ` Andi Kleen
2008-08-09 0:36 ` Steven Rostedt
2008-08-09 0:47 ` Jeremy Fitzhardinge
2008-08-09 0:51 ` Linus Torvalds
2008-08-09 1:25 ` Steven Rostedt
2008-08-13 6:31 ` Mathieu Desnoyers
2008-08-13 15:38 ` Mathieu Desnoyers
2008-08-13 17:52 ` Efficient x86 and x86_64 NOP microbenchmarks Mathieu Desnoyers
2008-08-13 18:27 ` Linus Torvalds
2008-08-13 18:41 ` Andi Kleen
2008-08-13 18:45 ` Avi Kivity
2008-08-13 18:51 ` Andi Kleen
2008-08-13 18:56 ` Avi Kivity
2008-08-13 19:30 ` Mathieu Desnoyers
2008-08-13 19:37 ` Andi Kleen
2008-08-13 20:01 ` Mathieu Desnoyers
2008-08-13 23:41 ` [RFC PATCH] x86 alternatives : fix LOCK_PREFIX race with preemptible kernel and CPU hotplug Mathieu Desnoyers
2008-08-14 0:01 ` H. Peter Anvin
2008-08-14 1:13 ` Mathieu Desnoyers
2008-08-14 1:22 ` Jeremy Fitzhardinge
2008-08-14 1:26 ` Roland McGrath
2008-08-14 1:49 ` Mathieu Desnoyers
2008-08-14 3:35 ` Jeremy Fitzhardinge
2008-08-14 15:18 ` Mathieu Desnoyers
2008-08-14 16:10 ` Linus Torvalds
2008-08-14 16:13 ` H. Peter Anvin
2008-08-14 16:58 ` Mathieu Desnoyers
2008-08-14 17:05 ` Jeremy Fitzhardinge
2008-08-14 17:30 ` Mathieu Desnoyers
2008-08-14 17:43 ` Jeremy Fitzhardinge
2008-08-14 18:37 ` H. Peter Anvin [this message]
2008-08-14 18:53 ` Mathieu Desnoyers
2008-08-14 19:29 ` Jeremy Fitzhardinge
2008-08-14 20:31 ` Mathieu Desnoyers
2008-08-14 20:39 ` H. Peter Anvin
2008-08-14 21:46 ` Jeremy Fitzhardinge
2008-08-14 22:26 ` H. Peter Anvin
2008-08-14 17:17 ` H. Peter Anvin
2008-08-14 18:09 ` Mathieu Desnoyers
2008-08-14 19:49 ` Mathieu Desnoyers
2008-08-14 17:04 ` Jeremy Fitzhardinge
2008-08-14 17:18 ` H. Peter Anvin
2008-08-14 17:28 ` Jeremy Fitzhardinge
2008-08-14 17:31 ` H. Peter Anvin
2008-08-14 17:46 ` Mathieu Desnoyers
2008-08-14 17:49 ` Jeremy Fitzhardinge
2008-08-14 17:55 ` Mathieu Desnoyers
2008-08-14 18:59 ` Gregory Haskins
2008-08-15 21:34 ` Efficient x86 and x86_64 NOP microbenchmarks Steven Rostedt
2008-08-15 21:51 ` Andi Kleen
2008-08-13 19:16 ` Mathieu Desnoyers
2008-08-09 0:51 ` [PATCH 0/5] ftrace: to kill a daemon Steven Rostedt
2008-08-09 0:53 ` Roland McGrath
2008-08-09 1:13 ` Andi Kleen
2008-08-09 1:19 ` Andi Kleen
2008-08-09 1:30 ` Steven Rostedt
2008-08-09 1:55 ` Andi Kleen
2008-08-09 2:03 ` Steven Rostedt
2008-08-09 2:23 ` Andi Kleen
2008-08-09 4:12 ` Steven Rostedt
2008-08-09 0:30 ` Steven Rostedt
2008-08-11 18:21 ` Mathieu Desnoyers
2008-08-11 19:28 ` Steven Rostedt
2008-08-08 19:08 ` Jeremy Fitzhardinge
2008-08-11 2:41 ` Rusty Russell
2008-08-11 12:33 ` Steven Rostedt
2008-08-07 21:11 ` Jeremy Fitzhardinge
2008-08-07 21:29 ` Steven Rostedt
2008-08-07 22:26 ` Roland McGrath
2008-08-08 1:21 ` Steven Rostedt
2008-08-08 1:24 ` Steven Rostedt
2008-08-08 1:56 ` Steven Rostedt
2008-08-08 7:22 ` Peter Zijlstra
2008-08-08 11:31 ` Steven Rostedt
2008-08-08 4:54 ` Sam Ravnborg
2008-08-09 9:48 ` Abhishek Sagar
2008-08-09 13:01 ` Steven Rostedt
2008-08-09 15:01 ` Abhishek Sagar
2008-08-09 15:37 ` Steven Rostedt
2008-08-09 17:14 ` Abhishek Sagar
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