lkml.org 
[lkml]   [2015]   [May]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [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


\
 
 \ /
  Last update: 2015-05-20 21:41    [W:0.121 / U:0.560 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site