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From: Namhyung Kim <namhyung@kernel.org>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>,
        Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@kernel.org>,
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Subject: Re: [RFC PATCH tip 0/5] tracing filters with BPF
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Date: Mon, 09 Dec 2013 16:29:48 +0900
In-Reply-To: <529E81C1.2070208@hitachi.com> (Masami Hiramatsu's message of
	"Wed, 04 Dec 2013 10:13:37 +0900")
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Hi Masami,

On Wed, 04 Dec 2013 10:13:37 +0900, Masami Hiramatsu wrote:
> (2013/12/04 3:26), Alexei Starovoitov wrote:
>> the only inconvenience so far is to know how parameters are getting
>> into registers.
>> on x86-64, arg1 is in rdi, arg2 is in rsi,... I want to improve that
>> after first step is done.
>
> Actually, that part is done by the perf-probe and ftrace dynamic events
> (kernel/trace/trace_probe.c). I think this generic BPF is good for
> re-implementing fetch methods. :)

For implementing patch method, it seems that it needs to access to user
memory, stack and/or current (task_struct - for utask or vma later) from
the BPF VM as well.  Isn't it OK from the security perspective?

Anyway, I'll take a look at it later if I have time, but I want to get
the existing/pending implementation merged first. :)

Thanks,
Namhyung