[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <alpine.LNX.2.00.1505202105580.8186@pobox.suse.cz>
Date: Wed, 20 May 2015 21:10:16 +0200 (CEST)
From: Jiri Kosina <jkosina@...e.cz>
To: Peter Zijlstra <peterz@...radead.org>
cc: Andy Lutomirski <luto@...capital.net>,
Ingo Molnar <mingo@...nel.org>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, Michal Marek <mmarek@...e.cz>,
X86 ML <x86@...nel.org>, live-patching@...r.kernel.org,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Andy Lutomirski <luto@...nel.org>,
Denys Vlasenko <dvlasenk@...hat.com>,
Brian Gerst <brgerst@...il.com>,
Borislav Petkov <bp@...en8.de>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v4 0/3] Compile-time stack frame pointer validation
On Wed, 20 May 2015, Peter Zijlstra wrote:
> > I think it would be nice to have full DWARF unwind support for
> > everything at some point. Unfortunately, I don't see any easy path to
> > getting there. It doesn't help that AFAIK no one has ever proposed a
> > usable in-kernel DWARF unwinder.
>
> There's a bit of history here; SuSE (iirc) actually has one, however:
>
> https://lkml.org/lkml/2012/2/10/356
Oh absolutely, there are stories behind this :)
Just for the sake of completness -- the current implementation can be
found in our public GIT repository, for not-really-complete picture see
[1] [2] [3] [4].
It turned out to be rather useful on many ocasions when debugging customer
reports, but I of course also understand what Linus is saying above. The
bugs in unwinder can be *really* painful. Our experience so far has been
that it did pay off at the end of the day (and of course analyzing
stacktraces is our daily bread).
[1] http://kernel.suse.com/cgit/kernel-source/tree/patches.suse/stack-unwind?h=SLE12
[2] http://kernel.suse.com/cgit/kernel-source/tree/patches.suse/no-frame-pointer-select?h=SLE12
[3] http://kernel.suse.com/cgit/kernel-source/tree/patches.arch/stack-unwind-cfi_ignore-takes-more-arguments?h=SLE12
[4] http://kernel.suse.com/cgit/kernel-source/tree/patches.arch/x86_64-unwind-annotations?h=SLE12
--
Jiri Kosina
SUSE Labs
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists