linux-kernel - Re: RFC: How to handle function tracing, frame pointers and -mfentry?

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]

Date:	Sat, 28 Apr 2012 10:36:03 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	linux-kbuild <linux-kbuild@...r.kernel.org>,
	Michal Marek <mmarek@...e.cz>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>, Ingo Molnar <mingo@...e.hu>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: RFC: How to handle function tracing, frame pointers and -mfentry?

> 1) Have kconfig detect if -mfentry is supported with the current
> compiler. If it is, then enable a "auto" config called
> CONFIG_CC_HAS_FENTRY, and allow function tracer be able to select
> FRAME_POINTER if that's not defined.
> 
> I actually got this to work, but it only works if the host compiler is
> the same as the compiler building the kernel. Which in lots of cases is
> not (my default setup does not have this).

Kconfig just needs to learn how to run the target compiler

I think that's the right direction. Right now our main
Makefiles get polluted more and more with "test compiles", each
of which makes a "null make" slower and slower. 

I just measured and a null compile (nothing changes) of a current
tree calls "gcc" 141 times.

All this stuff should be cached in the Kconfig instead.

It may break some obscure setups (that can be probably fixed without
too much effort), but the development turnaround improvement
for everyone else would be worth it.

-Andi
-- 
ak@...ux.intel.com -- Speaking for myself only.
--
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/