From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: Martin Bligh <mbligh@google.com>,
prasanna@in.ibm.com, Andrew Morton <akpm@osdl.org>,
"Frank Ch. Eigler" <fche@redhat.com>, Ingo Molnar <mingo@elte.hu>,
Paul Mundt <lethal@linux-sh.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Jes Sorensen <jes@sgi.com>, Tom Zanussi <zanussi@us.ibm.com>,
Richard J Moore <richardj_moore@uk.ibm.com>,
Michel Dagenais <michel.dagenais@polymtl.ca>,
Christoph Hellwig <hch@infradead.org>,
Greg Kroah-Hartman <gregkh@suse.de>,
Thomas Gleixner <tglx@linutronix.de>,
William Cohen <wcohen@redhat.com>,
ltt-dev@shafik.org, systemtap@sources.redhat.com
Subject: Re: [PATCH] Linux Kernel Markers
Date: Wed, 20 Sep 2006 01:08:45 +0100 [thread overview]
Message-ID: <1158710925.32598.120.camel@localhost.localdomain> (raw)
In-Reply-To: <20060919175405.GC26339@Krystal>
Ar Maw, 2006-09-19 am 13:54 -0400, ysgrifennodd Mathieu Desnoyers:
> Very good idea.. However, overwriting the second instruction with a jump could
> be dangerous on preemptible and SMP kernels, because we never know if a thread
> has an IP in any of its contexts that would return exactly at the middle of the
> jump.
No: on x86 it is the *same* case for all of these even writing an int3.
One byte or a megabyte,
You MUST ensure that every CPU executes a serializing instruction before
it hits code that was modified by another processor. Otherwise you get
CPU errata and the CPU produces results which vendors like to describe
as "undefined".
Thus you have to serialize, and if you are serializing it really doesn't
matter if you write a byte, a paragraph or a page.
Alan
next prev parent reply other threads:[~2006-09-19 23:46 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-18 23:45 Mathieu Desnoyers
2006-09-19 0:41 ` Alan Cox
2006-09-19 1:10 ` Dave Jones
2006-09-19 8:11 ` Ingo Molnar
2006-09-19 8:13 ` Ingo Molnar
2006-09-19 15:11 ` Martin J. Bligh
2006-09-19 15:31 ` Ingo Molnar
2006-09-20 11:19 ` Andi Kleen
2006-09-19 15:46 ` Frank Ch. Eigler
2006-09-19 16:04 ` Martin Bligh
2006-09-19 16:39 ` Andrew Morton
2006-09-19 16:41 ` Martin Bligh
2006-09-19 6:38 ` S. P. Prasanna
2006-09-19 17:17 ` Martin Bligh
2006-09-19 7:05 ` S. P. Prasanna
2006-09-19 18:02 ` Martin Bligh
2006-09-19 21:04 ` Karim Yaghmour
2006-09-20 13:27 ` Masami Hiramatsu
2006-09-20 17:21 ` Karim Yaghmour
2006-09-20 17:15 ` Mathieu Desnoyers
2006-09-20 17:35 ` Karim Yaghmour
2006-09-20 18:08 ` Frank Ch. Eigler
2006-09-20 18:22 ` Martin Bligh
2006-09-20 18:50 ` Karim Yaghmour
2006-09-20 19:22 ` Martin Bligh
2006-09-20 19:43 ` Karim Yaghmour
2006-09-20 19:40 ` Martin Bligh
2006-09-20 19:58 ` Karim Yaghmour
2006-09-20 18:25 ` Karim Yaghmour
2006-09-20 17:41 ` Karim Yaghmour
2006-09-19 17:54 ` Mathieu Desnoyers
2006-09-19 18:01 ` Martin Bligh
2006-09-19 18:11 ` Mathieu Desnoyers
2006-09-20 0:08 ` Alan Cox [this message]
2006-09-20 0:52 ` Karim Yaghmour
2006-09-20 10:44 ` Alan Cox
2006-09-20 23:00 ` Richard J Moore
2006-09-23 15:34 ` score-boarding [was Re: [PATCH] Linux Kernel Markers] Hugh Dickins
2006-09-26 8:43 ` Richard J Moore
2006-09-20 1:08 ` [PATCH] Linux Kernel Markers S. P. Prasanna
2006-09-20 8:18 ` Richard J Moore
2006-09-20 10:32 ` Alan Cox
2006-09-20 11:50 ` Andi Kleen
2006-09-20 13:45 ` Richard J Moore
2006-09-22 12:33 ` Pavel Machek
2006-09-20 1:09 ` Mathieu Desnoyers
2006-09-19 19:13 ` Vara Prasad
2006-09-19 19:16 ` Mathieu Desnoyers
2006-09-19 19:24 ` Martin Bligh
2006-09-19 22:27 ` Satoshi Oshima
2006-09-19 19:26 ` Martin Bligh
2006-09-19 9:30 ` S. P. Prasanna
2006-09-19 20:12 ` Mathieu Desnoyers
2006-09-20 11:00 ` Masami Hiramatsu
2006-09-20 9:39 ` Helge Hafting
2006-09-20 10:30 ` Alan Cox
2006-09-20 13:23 ` Masami Hiramatsu
2006-09-19 16:36 ` Ingo Molnar
2006-09-19 16:41 ` Richard J Moore
2006-09-19 16:49 ` Frank Ch. Eigler
2006-09-19 16:52 ` Martin Bligh
2006-09-19 17:02 ` Frank Ch. Eigler
2006-09-19 16:06 ` Vara Prasad
2006-09-19 16:14 ` Martin Bligh
2006-09-19 17:43 ` Mathieu Desnoyers
2006-09-19 16:23 ` Karim Yaghmour
2006-09-19 16:17 ` Martin Bligh
2006-09-19 16:29 ` Karim Yaghmour
2006-09-19 16:55 ` Karim Yaghmour
2006-09-19 17:41 ` Mathieu Desnoyers
2006-09-20 17:33 ` Karim Yaghmour
2006-09-19 15:21 ` Frank Ch. Eigler
2006-09-20 13:20 ` Masami Hiramatsu
2006-09-20 13:32 ` Mathieu Desnoyers
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