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From: Namhyung Kim <namhyung@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>, Namhyung Kim <namhyung.kim@lge.com>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        Hyeoncheol Lee <cheol.lee@lge.com>,
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        "zhangwei\(Jovi\)" <jovi.zhangwei@huawei.com>,
        Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Subject: Re: [PATCHSET 00/13] tracing/uprobes: Add support for more fetch methods (v6)
References: <20131104155131.GD4440@redhat.com>
	<20131104162229.GA8921@redhat.com> <20131104184741.GA15945@redhat.com>
	<87sivbz65t.fsf@sejong.aot.lge.com> <20131105174535.GA6385@redhat.com>
	<20131105192401.GA772@redhat.com> <87vc05x5zf.fsf@sejong.aot.lge.com>
	<20131106173754.GA11299@redhat.com>
	<20131106182408.GA12922@redhat.com>
	<8761s4wprj.fsf@sejong.aot.lge.com>
	<20131108170017.GB28753@redhat.com>
Date: Tue, 12 Nov 2013 16:49:30 +0900
In-Reply-To: <20131108170017.GB28753@redhat.com> (Oleg Nesterov's message of
	"Fri, 8 Nov 2013 18:00:17 +0100")
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Hi Oleg,

On Fri, 8 Nov 2013 18:00:17 +0100, Oleg Nesterov wrote:
> On 11/07, Namhyung Kim wrote:
>>
>> On Wed, 6 Nov 2013 19:24:08 +0100, Oleg Nesterov wrote:
>> >
>> > Note that instruction_pointer_set() is not really nice in any case,
>> > this can obviously confuse FETCH_MTD_reg("ip").
>>
>> Yes.
>>
>> >
>> > But lets ignore this. The solution is simple, we can pass/use this
>> > info via current->utask. We can either add the new member, or add
>> > a union. Or simply reuse xol_vaddr. Doesn't matter.
>>
>> Okay, I'll take a look.
>
> I guess we need the union in uprobe_task anyway... I'll send the patch
> soon.
>
> Until we have the new members in uprobe_task, you can reuse utask->vaddr,
> this is safe.
>
> IOW, you can use current->utask->vaddr instead of regs->ip (as we did
> in the previous discussin) to pass the necessary info to ->fetch().

Thanks for the info!
Namhyung