linux-kernel - Re: [PATCH 1/2] x86/stacktrace: do not fail when regs on stack for ORC

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Message-ID: <20171220174544.g34v2lkjrz2r6kh7@treble>
Date:   Wed, 20 Dec 2017 11:45:44 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Jiri Slaby <jslaby@...e.cz>
Cc:     mingo@...hat.com, linux-kernel@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Subject: Re: [PATCH 1/2] x86/stacktrace: do not fail when regs on stack for
 ORC

On Sun, Dec 17, 2017 at 09:37:49PM -0600, Josh Poimboeuf wrote:
> > 
> > So making it:
> >         if (!(task->flags & (PF_KTHREAD | PF_IDLE)))
> >                 return -EINVAL;
> > 
> > works, but is not reliable now. So I believe, we cannot live without
> > unwind->error to differentiate between "unwind_done() == true" because:
> > * full stack unwound and the stack type is set to UNKNOWN
> > * unwinding failed and the stack type is set to UNKNOWN
> > 
> > Or perhaps introduce stack type BOTTOM, NONE, or NOMORE meaning the
> > bottom of the stacks reached?
> 
> Yeah, we'll need something... I need to think about it a little more.

I can update the ORC unwinder to set unwind->error in case it runs into
an issue or it doesn't reach the "end", like the FP unwinder does.

It might not be until 2018 though.  But in the meantime you can go ahead
and update your patches accordingly and then we can combine them for
testing next year.

-- 
Josh