From: Masami Hiramatsu <mhiramat@redhat.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
Ingo Molnar <mingo@elte.hu>,
Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
lkml <linux-kernel@vger.kernel.org>,
systemtap <systemtap@sources.redhat.com>,
DLE <dle-develop@lists.sourceforge.net>,
Jim Keniston <jkenisto@us.ibm.com>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Christoph Hellwig <hch@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Anders Kaseorg <andersk@ksplice.com>,
Tim Abbott <tabbott@ksplice.com>,
Andi Kleen <andi@firstfloor.org>,
Jason Baron <jbaron@redhat.com>,
Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Subject: Re: [PATCH -tip v5 07/10] kprobes/x86: Support kprobes jump optimization on x86
Date: Tue, 24 Nov 2009 17:01:00 -0000 [thread overview]
Message-ID: <4B0C1141.3070807@redhat.com> (raw)
In-Reply-To: <4B0C0B50.6000907@zytor.com>
Hi Peter,
H. Peter Anvin wrote:
> On 11/23/2009 03:22 PM, Masami Hiramatsu wrote:
>>
>> This uses stop_machine() for corss modifying code from int3 to jump.
>> It doesn't allow us to modify code on NMI/SMI path. However, since
>> kprobes itself doesn't support NMI/SMI code probing, it's not a
>> problem.
>>
>
> I'm a bit confused by the above statement... does that mean you're
> poking int3 and *then* do stop_machine()?
Yes, as I said in http://lkml.org/lkml/2009/11/24/310,
there are two separated issues.
----
We have to separate below issues:
- int3-based multi-bytes code replacement
- multi-instruction replacement with int3-detour code
The former is implemented on patch 9/10 and 10/10. As you can see,
these patches are RFC status, because I'd like to wait for official
reply of safeness from processor architects.
And it may be able to use a dummy IPI for 2nd IPI because it
just for waiting int3 interrupts. But again, it is just estimated that
replacing with/recovering from int3 is automatically synchronized...
However, at least stop_machine() method is officially described
at "7.1.3 Handling Self- and Cross-Modifying Code" on the intel's
software developer's manual 3A . So currently we can use it.
For the latter issue, as I explained on previous reply, we need
to wait all running interrupts including hardware interrupts.
Thus I used synchronize_sched().
----
So that the previous "x86 generic jump patching" patch is
basically for single-instruction replacement. For multi-instructions
replacement, we need to make detour code and wait for all running
interruption. (of course, there are other static code limitations,
as I described at "Safety check" section in patch 0/10.)
Thank you,
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com
next prev parent reply other threads:[~2009-11-24 17:01 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-23 23:18 [PATCH -tip v5 00/10] kprobes: Kprobes jump optimization support Masami Hiramatsu
2009-11-23 23:18 ` [PATCH -tip v5 02/10] kprobes: Introduce generic insn_slot framework Masami Hiramatsu
2009-11-23 23:18 ` [PATCH -tip v5 01/10] kprobes/x86: Cleanup RELATIVEJUMP_INSTRUCTION to RELATIVEJUMP_OPCODE Masami Hiramatsu
2009-11-23 23:19 ` [PATCH -tip v5 06/10] kprobes/x86: Cleanup save/restore registers Masami Hiramatsu
2009-11-24 2:51 ` Frederic Weisbecker
2009-11-24 15:36 ` Masami Hiramatsu
2009-11-24 20:19 ` Frederic Weisbecker
2009-11-24 15:40 ` Frank Ch. Eigler
2009-11-24 20:20 ` Frederic Weisbecker
2009-11-23 23:19 ` [PATCH -tip v5 04/10] kprobes: Jump optimization sysctl interface Masami Hiramatsu
2009-11-23 23:19 ` [PATCH -tip v5 03/10] kprobes: Introduce kprobes jump optimization Masami Hiramatsu
2009-11-24 2:44 ` Frederic Weisbecker
2009-11-24 3:31 ` Frederic Weisbecker
2009-11-24 15:32 ` Masami Hiramatsu
2009-11-24 20:14 ` Frederic Weisbecker
2009-11-24 20:59 ` Masami Hiramatsu
2009-11-25 21:09 ` Steven Rostedt
2009-11-25 21:30 ` Masami Hiramatsu
2009-11-24 21:12 ` H. Peter Anvin
2009-11-24 15:31 ` Masami Hiramatsu
2009-11-24 19:45 ` Frederic Weisbecker
2009-11-24 21:15 ` Masami Hiramatsu
2009-11-23 23:19 ` [PATCH -tip v5 07/10] kprobes/x86: Support kprobes jump optimization on x86 Masami Hiramatsu
2009-11-24 3:15 ` Frederic Weisbecker
2009-11-24 16:27 ` Jason Baron
2009-11-24 17:46 ` Masami Hiramatsu
2009-11-25 16:12 ` Masami Hiramatsu
2009-11-24 16:42 ` H. Peter Anvin
2009-11-24 17:01 ` Masami Hiramatsu [this message]
2009-11-23 23:19 ` [PATCH -tip v5 05/10] kprobes/x86: Boost probes when reentering Masami Hiramatsu
2009-11-23 23:19 ` [PATCH -tip v5 08/10] kprobes: Add documents of jump optimization Masami Hiramatsu
2009-11-23 23:19 ` [PATCH -tip v5 09/10] [RFC] x86: Introduce generic jump patching without stop_machine Masami Hiramatsu
2009-11-23 23:19 ` [PATCH -tip v5 10/10] [RFC] kprobes/x86: Use text_poke_fixup() for jump optimization Masami Hiramatsu
2009-11-24 2:03 ` [PATCH -tip v5 00/10] kprobes: Kprobes jump optimization support Frederic Weisbecker
2009-11-24 3:20 ` Frederic Weisbecker
2009-11-24 7:53 ` Ingo Molnar
2009-11-24 16:03 ` Masami Hiramatsu
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