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From: Daniel Axtens <dja@axtens.net>
To: Dmitry Vyukov <dvyukov@google.com>,
	Christophe Leroy <christophe.leroy@c-s.fr>
Cc: linux-s390 <linux-s390@vger.kernel.org>,
	linux-xtensa@linux-xtensa.org,
	the arch/x86 maintainers <x86@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	kasan-dev <kasan-dev@googlegroups.com>,
	Linux-MM <linux-mm@kvack.org>,
	Daniel Micay <danielmicay@gmail.com>,
	Alexander Potapenko <glider@google.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 1/2] kasan: stop tests being eliminated as dead code with FORTIFY_SOURCE
Date: Thu, 16 Jan 2020 16:34:23 +1100	[thread overview]
Message-ID: <87zheoj76o.fsf@dja-thinkpad.axtens.net> (raw)
In-Reply-To: <CACT4Y+Y-qPLzn2sur5QnS2h4=Qb2B_5rFxwMKuzhe-hwsReGqg@mail.gmail.com>

>> >> +/*
>> >> + * We assign some test results to these globals to make sure the tests
>> >> + * are not eliminated as dead code.
>> >> + */
>> >> +
>> >> +int int_result;
>> >> +void *ptr_result;
>> >
>> > These are globals, but are not static and don't have kasan_ prefix.
>> > But I guess this does not matter for modules?
>> > Otherwise:
>> >
>> > Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
>> >
>>
>> I think if you make them static, GCC will see they aren't used and will
>> eliminate everything still ?
>
> static volatile? :)

Yeah so these are module globals. They'd be accessible from any other
files you linked into the module (currently there are no such
files). They're not visible outside the module because they're not
EXPORTed.

Making them static does lead to them getting eliminated, and 'static
volatile' seems both gross and like something checkpatch would complain
about. I'll leave them as they are but stick a kasan_ prefix on them
just for the additional tidiness.

Regards,
Daniel

  reply	other threads:[~2020-01-16  5:34 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-15  6:37 [PATCH 0/2] Fix some incompatibilites between KASAN and FORTIFY_SOURCE Daniel Axtens
2020-01-15  6:37 ` [PATCH 1/2] kasan: stop tests being eliminated as dead code with FORTIFY_SOURCE Daniel Axtens
2020-01-15 14:43   ` Dmitry Vyukov
2020-01-15 14:47     ` Christophe Leroy
2020-01-15 14:57       ` Dmitry Vyukov
2020-01-16  5:34         ` Daniel Axtens [this message]
2020-01-15  6:37 ` [PATCH 2/2] string.h: fix incompatibility between FORTIFY_SOURCE and KASAN Daniel Axtens
2020-01-15 14:56   ` Dmitry Vyukov
2020-01-16  4:59     ` Daniel Axtens
2020-01-16  5:47       ` Dmitry Vyukov
2020-01-16 23:52   ` kbuild test robot

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