linux-kernel - Re: [PATCH -tip RFC v2 01/22] kprobes: Prohibit probing on .entry.text code

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Date:	Fri, 15 Nov 2013 18:46:40 +0100
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Ingo Molnar <mingo@...nel.org>,
	Linux-Arch <linux-arch@...r.kernel.org>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	"the arch/x86 maintainers" <x86@...nel.org>,
	lkml <linux-kernel@...r.kernel.org>,
	virtualization@...ts.linux-foundation.org,
	Ingo Molnar <mingo@...hat.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Seiji Aguchi <seiji.aguchi@....com>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH -tip RFC v2 01/22] kprobes: Prohibit probing on
 .entry.text code

On Fri, Nov 15, 2013 at 5:43 PM, Steven Rostedt <rostedt@...dmis.org> wrote:
> On Fri, 15 Nov 2013 04:53:18 +0000
> Masami Hiramatsu <masami.hiramatsu.pt@...achi.com> wrote:
>
>> .entry.text is a code area which is used for interrupt/syscall
>> entries, and there are many sensitive codes.
>> Thus, it is better to prohibit probing on all of such codes
>> instead of a part of that.
>> Since some symbols are already registered on kprobe blacklist,
>> this also removes them from the blacklist.
>
> This change only works with x86. On other archs, I get this:
>
> kernel/built-in.o: In function `register_kprobe':
> (.kprobes.text+0x9f4): undefined reference to `__entry_text_start'
> kernel/built-in.o: In function `register_kprobe':
> (.kprobes.text+0x9f8): undefined reference to `__entry_text_end'
> make[1]: *** [vmlinux] Error 1
> make: *** [sub-make] Error 2

X86 is the sole architecture that has ENTRY_TEXT in its
arch/*/kernel/vmlinux.lds.S.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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