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From: Borislav Petkov <bp@alien8.de>
To: "H. Peter Anvin" <hpa@linux.intel.com>
Cc: Jiri Kosina <jkosina@suse.cz>,
	Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Jason Baron <jbaron@redhat.com>,
	Borislav Petkov <bpetkov@suse.de>,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC] [PATCH 1/2 v2] x86: introduce int3-based instruction patching
Date: Wed, 10 Jul 2013 23:48:48 +0200	[thread overview]
Message-ID: <20130710214848.GB14879@pd.tnic> (raw)
In-Reply-To: <51DDD3E9.6090601@linux.intel.com>

On Wed, Jul 10, 2013 at 02:36:41PM -0700, H. Peter Anvin wrote:
> I'm wondering if it would be easier/more general to just return to the
> instruction. The "more general" bit would allow this to be used for
> other things, like alternatives, and perhaps eventually dynamic call
> patching.

Well, the aspect of not using stop_machine in alternatives is a don't
care because there we do text_poke_early on the BSP anyway. However,
there we toggle interrupts so it would probably be interesting to see
whether a non-interrupt-disabling variant would be faster.

> Returning to the instruction will, in effect, be a busy-wait for
> the faulted CPU until the patch is complete; more or less what
> stop_machine would do, but only for a CPU which actually strays into
> the affected region.

Oh, something like we patch in a two-byte jump first:

1:
	jmp 1b

until we finish patching the rest? Ha, interesting :).

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
--

  reply	other threads:[~2013-07-10 21:49 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-10 20:25 [RFC] [PATCH 0/2] x86: make jump labels use int3-based breakpoint instead of stop_machine() Jiri Kosina
2013-07-10 20:25 ` [RFC] [PATCH 1/2] x86: introduce int3-based instruction patching Jiri Kosina
2013-07-10 21:31   ` [RFC] [PATCH 1/2 v2] " Jiri Kosina
2013-07-10 21:36     ` H. Peter Anvin
2013-07-10 21:48       ` Borislav Petkov [this message]
2013-07-10 21:56         ` H. Peter Anvin
2013-07-10 22:14           ` Borislav Petkov
2013-07-10 22:39       ` Jiri Kosina
2013-07-11  3:29       ` Masami Hiramatsu
2013-07-11 10:09       ` Jiri Kosina
2013-07-11 10:54         ` Jiri Kosina
2013-07-11 16:31         ` H. Peter Anvin
2013-07-11 16:46           ` Steven Rostedt
2013-07-11 19:21             ` Jiri Kosina
2013-07-12  1:00             ` Masami Hiramatsu
2013-07-11 14:35       ` Steven Rostedt
2013-07-11 14:47         ` Jason Baron
2013-07-10 21:46     ` Joe Perches
2013-07-11 10:23     ` Masami Hiramatsu
2013-07-11 10:51       ` Jiri Kosina
2013-07-12  0:50         ` Masami Hiramatsu
2013-07-11 16:10       ` H. Peter Anvin
2013-07-11 19:29         ` Jiri Kosina
2013-07-11 20:49           ` H. Peter Anvin
2013-07-11 20:51           ` H. Peter Anvin
2013-07-11 15:57     ` Steven Rostedt
2013-07-11 19:43       ` Jiri Kosina
2013-07-11 19:52         ` Steven Rostedt
2013-07-10 20:25 ` [RFC] [PATCH 2/2] x86: make jump_label use int3-based patching Jiri Kosina
2013-07-10 22:26 ` [RFC] [PATCH 0/2] x86: make jump labels use int3-based breakpoint instead of stop_machine() Jason Baron
2013-07-11  0:04   ` Jiri Kosina
2013-07-11 16:42     ` Steven Rostedt
2013-07-11 19:23       ` Jiri Kosina
2013-07-11 19:54         ` Steven Rostedt
2013-07-11  2:21 ` Masami Hiramatsu
2013-07-11 20:26 ` [PATCH 2/2 v3] x86: make jump_label use int3-based patching Jiri Kosina
2013-07-12  2:12   ` Steven Rostedt
2013-07-12  5:44   ` Masami Hiramatsu
2013-07-11 20:26 ` [PATCH 1/2 v3] x86: introduce int3-based instruction patching Jiri Kosina
2013-07-11 20:53   ` H. Peter Anvin
2013-07-11 21:04     ` Borislav Petkov
2013-07-11 21:36       ` H. Peter Anvin
2013-07-12  7:57         ` Borislav Petkov
2013-07-17  3:59           ` H. Peter Anvin
2013-07-11 22:31     ` Jiri Kosina
2013-07-12  2:09       ` Steven Rostedt
2013-07-11 23:01   ` Joe Perches
2013-07-12  2:07   ` Steven Rostedt
2013-07-12  2:40   ` Masami Hiramatsu
2013-07-12  9:21 ` [PATCH 1/2 v4] " Jiri Kosina
2013-07-17  1:18   ` [tip:x86/jumplabel] x86: Introduce int3 (breakpoint) -based " tip-bot for Jiri Kosina
2013-07-12  9:22 ` [PATCH 2/2 v4] x86: make jump_label use int3-based patching Jiri Kosina
2013-07-17  1:18   ` [tip:x86/jumplabel] x86: Make " tip-bot for Jiri Kosina

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