lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Tue, 02 Mar 2010 19:35:54 -0500
From:	Masami Hiramatsu <mhiramat@...hat.com>
To:	Mathieu Desnoyers <compudj@...stal.dyndns.org>
CC:	Ingo Molnar <mingo@...e.hu>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	lkml <linux-kernel@...r.kernel.org>,
	systemtap <systemtap@...rces.redhat.com>,
	DLE <dle-develop@...ts.sourceforge.net>,
	Jim Keniston <jkenisto@...ibm.com>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Christoph Hellwig <hch@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Anders Kaseorg <andersk@...lice.com>,
	Tim Abbott <tabbott@...lice.com>,
	Andi Kleen <andi@...stfloor.org>,
	Jason Baron <jbaron@...hat.com>
Subject: Re: [PATCH -tip v3&10 02/18] kprobes: Introduce generic insn_slot
 framework

Mathieu Desnoyers wrote:
> * Masami Hiramatsu (mhiramat@...hat.com) wrote:
>> Masami Hiramatsu wrote:
>>> Mathieu Desnoyers wrote:
>>>> * Masami Hiramatsu (mhiramat@...hat.com) wrote:
>>>>> Make insn_slot framework support various size slots.
>>>>> Current insn_slot just supports one-size instruction buffer slot. However,
>>>>> kprobes jump optimization needs larger size buffers.
>>>>
>>>> OK, so you end up having one insn slot cache for kprobes and one insn
>>>> slot (eventually) for the static jump patching (which needs larger
>>>> instruction slots than kprobes). That seems like a good way to ensure
>>>> you do not use more memory than necessary.
>>>>
>>>> We could possibly go even further and automatically use the right insn
>>>> slot cache given the size of the instruction entry that must be added (a
>>>> bit like the memory allocator which have different pools for each
>>>> allocation order).
>>>
>>> Sure, that will be simpler interface.
>>>
>>>> Possibly that using the terminology of "memory pools" rather than
>>>> "cache" could be a better fit too. So what this really becomes is an
>>>> instruction slot allocator and garbage collector.
>>>
>>> Ah, right. It would be better to rename kprobe_insn_pool() :)
>>
>> Hmm, I tried it. And finally, I found that this doesn't help
>> to simplify code... Maybe it is better to postpone it until
>> another user needs this feature.
> 
> I guess it's a tradeoff between the genericity of the API you provide
> and the complexity of the code that provides this API. So as you say,
> maybe it's better to wait until more users appears before improving the
> API.

OK, I'll hold that generalizing patch until that. :)

Thank you,
-- 
Masami Hiramatsu
e-mail: mhiramat@...hat.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists