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Date: Wed, 6 Nov 2013 07:07:37 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
        Ananth N Mavinakayanahalli <ananth@in.ibm.com>, x86@kernel.org,
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	<u.kleine-koenig@pengutronix.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Borislav Petkov <bp@suse.de>
Subject: Re: [PATCH -tip v2 3/3] [BUGFIX] kprobes: Prohibit probing on
 func_ptr_is_kernel_text
Message-ID: <20131106060737.GC24044@gmail.com>
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* Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> wrote:

> >> [...] I hope to build the list when the kernel build time if 
> >> possible... Would you have any idea to classify some annotated(but no 
> >> side-effect) functions?
> > 
> > The macro magic I can think of would need to change the syntax of the 
> > function definition - for example that is how the SYSCALL_DEFINE*() 
> > macros work.
> 
> Would you mean something like the below macro? :)
> 
> NOKPROBE_SYMBOL(int, func_ptr_is_kernel_text)(void *ptr)

I think this is rather ugly and harder to maintain. The whole _point_ of 
such annotations is to make them 'easy on the eyes', to make it easy to 
skip a 'noinline', 'noprobe' or 'notrace' tag.

Using something like NOKPROBE_SYMBOL() makes the whole construct ugly and 
attention seeking.

So until compilers get smarter (or there's some compiler trick I haven't 
noticed) lets stay with the separate section - it's not the end of the 
world, the (effective) 'noinline' aspect of noprobes changes code 
generation anyway.

Thanks,

	Ingo