linux-kernel - Re: [PATCH] ARM: dont specify STACKPROTECTOR in defconfigs

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Date:	Thu, 21 Jul 2016 14:04:37 -0400
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	Joel Stanley <joel@....id.au>
CC:	<linux-kernel@...r.kernel.org>,
	Russell King <linux@...linux.org.uk>,
	Florian Fainelli <f.fainelli@...il.com>,
	Ray Jui <rjui@...adcom.com>,
	Scott Branden <sbranden@...adcom.com>,
	Stephen Warren <swarren@...dotorg.org>,
	Lee Jones <lee@...nel.org>, Eric Anholt <eric@...olt.net>,
	<linux-arm-kernel@...ts.infradead.org>,
	<bcm-kernel-feedback-list@...adcom.com>
Subject: Re: [PATCH] ARM: dont specify STACKPROTECTOR in defconfigs

[Re: [PATCH] ARM: dont specify STACKPROTECTOR in defconfigs] On 22/07/2016 (Fri 01:40) Joel Stanley wrote:

> Hi Paul,
> 
> On Fri, Jul 22, 2016 at 12:41 AM, Paul Gortmaker
> <paul.gortmaker@...driver.com> wrote:
> > Note the output from the following:
> >
> >    $ git grep STACKPROTECTOR arch/arm/configs/
> >    arch/arm/configs/aspeed_g4_defconfig:CONFIG_CC_STACKPROTECTOR_STRONG=y
> >    arch/arm/configs/aspeed_g5_defconfig:CONFIG_CC_STACKPROTECTOR_STRONG=y
> >    arch/arm/configs/bcm2835_defconfig:CONFIG_CC_STACKPROTECTOR_REGULAR=y
> >    $
> >
> > Only three defconfigs specify a value.  And two of the three ask for
> > the strong variant, which isn't supported by older toolchains.
> >
> > Due to the nature of ARM having more platform specific code than say
> > x86, the allyesconfig and allmodconfig aren't as effective for build
> > coverage.  So, in addition, I like to use a trivial script to walk all
> > the defconfigs and build each one.
> >
> > However I will get false positives on unsupported stackprotector values
> > with an older toolchain like gcc-4.6.3.  As in this instance I am just
> > using the compiler as a glorified syntax checker on a machine where I
> > build a bunch of other arch for the same reason, there is no real
> > motivation to get a newer toolchain for improved optimization etc.
> 
> I'm happy to remove it from the Aspeed configurations as I'm not sure
> why it was enabled in the first place.
> 
> However, I do not agree with the reasoning here. If you're building to
> check syntax a modern GCC will certainly pick up on more than one from
> four years ago.

Just to clarify, syntax in this case is just for fat fingered typos and
ensuring functions resolve with the appropriate header includes.  If I
was coding new stuff specifically for ARM, then that would be different.

> 
> > Since there are only three of them, and there is nothing about these
> > settings that are board/platform specific, I propose we just eliminate
> > the three existing instances and take the default.
> 
> This makes sense to me.
> 
> Acked-by: Joel Stanley <joel@....id.au>

Thanks,
Paul.
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