linux-kernel - Re: [PATCH v2 06/11] x86/unwind/orc: Convert global variables to static

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Date: Wed, 28 Feb 2024 19:14:06 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Josh Poimboeuf <jpoimboe@...nel.org>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org,
 linux-kernel@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>, Vince
 Weaver <vincent.weaver@...ne.edu>, Dave Jones <dsj@...com>, Jann Horn
 <jannh@...gle.com>, Miroslav Benes <mbenes@...e.cz>, Andy Lutomirski
 <luto@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, Masami Hiramatsu
 <mhiramat@...nel.org>, Nilay Vaish <nilayvaish@...gle.com>
Subject: Re: [PATCH v2 06/11] x86/unwind/orc: Convert global variables to
 static

On Wed, 28 Feb 2024 16:03:09 -0800
Josh Poimboeuf <jpoimboe@...nel.org> wrote:

> On Wed, Feb 28, 2024 at 06:35:07PM -0500, Steven Rostedt wrote:
> > On Sat, 25 Apr 2020 05:03:05 -0500
> > Josh Poimboeuf <jpoimboe@...hat.com> wrote:
> >   
> > > These variables aren't used outside of unwind_orc.c, make them static.
> > > 
> > > Also annotate some of them with '__ro_after_init', as applicable.  
> > 
> > So it appears that crash uses "lookup_num_blocks" to be able to do
> > back-traces with the ORC unwinder. But because it's now static, crash can no
> > longer do that.  
> 
> Hm, but why?  Even a static variable has a known address.
> 

I'm guessing because we don't have the full dwarf info?

-- Steve