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Date: Tue, 15 Aug 2006 12:47:09 +0200
From: Andi Kleen <ak@muc.de>
To: "Jan Beulich" <jbeulich@novell.com>
Cc: "Andi Kleen" <ak@suse.de>, "Chuck Ebbert" <76306.1226@compuserve.com>,
       "Jesper Juhl" <jesper.juhl@gmail.com>, "Andrew Morton" <akpm@osdl.org>,
       "Dave Jones" <davej@redhat.com>,
       "linux-kernel" <linux-kernel@vger.kernel.org>
Subject: Re: [patch] i386: fix one case of stuck dwarf2 unwinder II
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On Tue, 15 Aug 2006 12:33:59 +0200
"Jan Beulich" <jbeulich@novell.com> wrote:

> >> So it would seem to me. Nevertheless, in my opinion the proper fix is
> to annotate the call site
> >> (in head.S) to specify a zero EIP as return address (which denotes
> the bottom of a frame).
> >
> >Can you please send a patch to do that?
> >
> >That seems to be missing in some other places too, e.g. i386 sysenter
> path, x86-64 kernel_thread,
> >more?
> 
> Attaching both an i386 version (boot/idle thread only, you did
> kernel_thread already)
> and an x86-64 one (boot/idle and kernel_thread). The i386 sysenter path
> is a different
> thing,

Ok added thanks.

Re One open question: Should this added push perhaps be made conditional
upon CONFIG_STACK_UNWIND or CONFIG_UNWIND_INFO?

I don't think that's needed because they are all slow paths.

 there we have an actual caller (though outside of the kernel),
> which I'd like to
> continue to reflect/catch through arch_unw_user_mode().

Ok, but does it work now? I thought it didn't.
I've also seen a stuck on the x86-64 sysenter path on x86-64.

-Andi