linux-kernel - Re: [PATCH -tip v2 3/3] [BUGFIX] kprobes: Prohibit probing on func_ptr_is_kernel

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Date:	Tue, 5 Nov 2013 08:13:10 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	x86@...nel.org, lkml <linux-kernel@...r.kernel.org>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Borislav Petkov <bp@...e.de>
Subject: Re: [PATCH -tip v2 3/3] [BUGFIX] kprobes: Prohibit probing on
 func_ptr_is_kernel_text

On Tue, 5 Nov 2013 08:05:37 +0100
Ingo Molnar <mingo@...nel.org> wrote:

> 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.

Or something like the EXPORT_SYMBOL(), but that wouldn't include the
size of the function. But using the name we could use kallsyms to see
if a probe is placed in a function that is blacklisted. Not very pretty
to do though.

> 
> It would be nice if there was a GCC extension that marked a function 
> noinline and allowed the emitting of the function's address (and size) 
> into a special section - but I'm not aware of any such compiler feature 
> today.

Yeah, I was wishing the same thing. Maybe I'll try to talk with the gcc
folks about adding such a feature. Something like

void  __attribute__((save_loc_and_size(".section"))) function(void)
{
}

-- Steve


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