linux-kernel - Re: [PATCH v4 06/14] x86: Add support for suppressing warning backtraces

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: <rkuxvq6pkha6pixz5rtu327ujt7ism5f4wgrak7egcecuxwe42@qkn5ewdzwhvo>
Date: Tue, 1 Apr 2025 13:00:55 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: Guenter Roeck <linux@...ck-us.net>
Cc: Peter Zijlstra <peterz@...radead.org>, 
	Alessandro Carminati <acarmina@...hat.com>, linux-kselftest@...r.kernel.org, 
	David Airlie <airlied@...il.com>, Arnd Bergmann <arnd@...db.de>, 
	Maíra Canal <mcanal@...lia.com>, Dan Carpenter <dan.carpenter@...aro.org>, 
	Kees Cook <keescook@...omium.org>, Daniel Diaz <daniel.diaz@...aro.org>, 
	David Gow <davidgow@...gle.com>, Arthur Grillo <arthurgrillo@...eup.net>, 
	Brendan Higgins <brendan.higgins@...ux.dev>, Naresh Kamboju <naresh.kamboju@...aro.org>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Andrew Morton <akpm@...ux-foundation.org>, 
	Maxime Ripard <mripard@...nel.org>, Ville Syrjälä <ville.syrjala@...ux.intel.com>, 
	Daniel Vetter <daniel@...ll.ch>, Thomas Zimmermann <tzimmermann@...e.de>, 
	Alessandro Carminati <alessandro.carminati@...il.com>, Jani Nikula <jani.nikula@...el.com>, 
	dri-devel@...ts.freedesktop.org, kunit-dev@...glegroups.com, linux-arch@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, linux-riscv@...ts.infradead.org, 
	linux-s390@...r.kernel.org, linux-sh@...r.kernel.org, loongarch@...ts.linux.dev, 
	x86@...nel.org, Linux Kernel Functional Testing <lkft@...aro.org>, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH v4 06/14] x86: Add support for suppressing warning
 backtraces

On Tue, Apr 01, 2025 at 10:53:46AM -0700, Guenter Roeck wrote:
> On 4/1/25 10:08, Peter Zijlstra wrote:
> > > +	if (!KUNIT_IS_SUPPRESSED_WARNING(__func__))			\
> > > +		_BUG_FLAGS(ASM_UD2, __flags, ANNOTATE_REACHABLE(1b));	\
> > >   	instrumentation_end();					\
> > >   } while (0)
> > 
> > NAK, this grows the BUG site for now appreciable reason.
> 
> Only if CONFIG_KUNIT_SUPPRESS_BACKTRACE is enabled. Why does that
> warrant a NACK ?

I agree with Peter, this bloats the code around thousands of UD2 sites.

It would be much better to do the checking after the exception.  In fact
it looks like you're already doing that in report_bug()?

	if (warning && KUNIT_IS_SUPPRESSED_WARNING(function))
		return BUG_TRAP_TYPE_WARN;

Why check it twice?

-- 
Josh