linux-kernel - Re: [for-next][PATCH 08/20] tracing: Warn if a tracepoint is not set via debugfs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140313031501.GW22728@two.firstfloor.org>
Date:	Thu, 13 Mar 2014 04:15:01 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	"Frank Ch. Eigler" <fche@...hat.com>, linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...nel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Johannes Berg <johannes.berg@...el.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	lttng-dev <lttng-dev@...ts.lttng.org>,
	Rusty Russell <rusty@...tcorp.com.au>
Subject: Re: [for-next][PATCH 08/20] tracing: Warn if a tracepoint is not
 set via debugfs

On Wed, Mar 12, 2014 at 08:47:07PM +0000, Mathieu Desnoyers wrote:
> ----- Original Message -----
> > From: "Andi Kleen" <andi@...stfloor.org>
> > To: "Mathieu Desnoyers" <mathieu.desnoyers@...icios.com>
> > Cc: "Steven Rostedt" <rostedt@...dmis.org>, "Frank Ch. Eigler" <fche@...hat.com>, linux-kernel@...r.kernel.org, "Ingo
> > Molnar" <mingo@...nel.org>, "Frederic Weisbecker" <fweisbec@...il.com>, "Andrew Morton" <akpm@...ux-foundation.org>,
> > "Johannes Berg" <johannes.berg@...el.com>, "Linus Torvalds" <torvalds@...ux-foundation.org>, "Peter Zijlstra"
> > <peterz@...radead.org>, "Thomas Gleixner" <tglx@...utronix.de>, "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
> > "lttng-dev" <lttng-dev@...ts.lttng.org>, "Rusty Russell" <rusty@...tcorp.com.au>, "Andi Kleen" <andi@...stfloor.org>
> > Sent: Wednesday, March 12, 2014 4:35:15 PM
> > Subject: Re: [for-next][PATCH 08/20] tracing: Warn if a tracepoint is not set via debugfs
> > 
> > > So I understand that you wish to banish tracepoints from static inline
> > > functions within headers to ensure they only appear within a single module.
> > > This seems to be a step backward, but let's assume we stick to that rule.
> > > Then how do you envision dealing with Link-Time Optimisations (LTO) ?
> > 
> > I assume it uses the file name defines set by Kbuild?
> 
> Just to make sure I understand your question: I understand that you are asking
> whether tracepoints use file name defines at all in the naming of a tracepoint.
> The answer to this question is: No, they do not.

Ok. It uses kallsyms? That can change of course.
> 
> > These don't change with
> > LTO. It's whatever was specified at compile time. Also LTO doesn't
> > inline over module boundaries (if the module is not built in)
> 
> Good to know. Can it inline core kernel functions into a module ?

Each module and the main kernel are currently LTO'ed separately.

In theory it would be possible to change this, but likely at some
compile time cost.

-Andi
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/