linux-kernel - Re: [RFC][PATCH 0/3] ftrace: Add dynamically allocated trampolines

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Message-ID: <20140710220137.GB19858@treble.redhat.com>
Date:	Thu, 10 Jul 2014 17:01:37 -0500
From:	Josh Poimboeuf <jpoimboe@...hat.com>
To:	Jiri Kosina <jkosina@...e.cz>
Cc:	Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Namhyung Kim <namhyung@...nel.org>,
	"H. Peter Anvin" <hpa@...or.com>, Oleg Nesterov <oleg@...hat.com>,
	Seth Jennings <sjenning@...hat.com>,
	Jiri Slaby <jslaby@...e.cz>
Subject: Re: [RFC][PATCH 0/3] ftrace: Add dynamically allocated trampolines

On Thu, Jul 10, 2014 at 11:44:43PM +0200, Jiri Kosina wrote:
> On Thu, 10 Jul 2014, Josh Poimboeuf wrote:
> 
> > I did some testing with kpatch and I found one minor issue.  The dynamically
> > allocated trampoline seems to confuse dump_stack() somewhat.
> > 
> > I added a dump_stack() call in my ftrace_ops callback function
> > (kpatch_ftrace_handler) which had a filter on meminfo_proc_show().
> 
> Interesting. Are you using dwarf2 unwinder for stack dumping by any 
> chance?

I think so (but not sure).  How can I check?  I do see the following
macros being defined in my kernel build:

  -DCONFIG_AS_CFI=1 -DCONFIG_AS_CFI_SIGNAL_FRAME=1 -DCONFIG_AS_CFI_SECTIONS=1

> It seems to get things right here. Will look into it more tomorrow.

Thanks, please let me know what you find...

-- 
Josh
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