linux-kernel - Re: [RFC PATCH 10/10] x86/unwind: add undwarf unwinder

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Message-ID: <20170601150339.q3yalx5kshuligaj@treble>
Date:   Thu, 1 Jun 2017 10:03:39 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        live-patching@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>, Jiri Slaby <jslaby@...e.cz>,
        Ingo Molnar <mingo@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [RFC PATCH 10/10] x86/unwind: add undwarf unwinder

On Thu, Jun 01, 2017 at 03:12:04PM +0200, Peter Zijlstra wrote:
> > Based on your previous comment I was thinking I would disable preemption
> > for the entire unwind_next_frame() step, but not *between* steps.  I
> > suppose we could require the unwind caller to disable preemption but I'd
> > like to avoid that if possible.
> 
> Right, keeping it disabled across a frame should be ok I suppose.

But then we'd either have to require the unwind user to explicitly
disable preemption, or we'd need to add a new unwind_end() interface
which the caller would be required to use when they're done unwinding.
Neither is ideal.

-- 
Josh