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Subject: Re: [PATCH] s390: Add WARN_DYNAMIC_STACK dependencies
To:     Guenter Roeck <linux@roeck-us.net>,
        Heiko Carstens <hca@linux.ibm.com>
Cc:     Vasily Gorbik <gor@linux.ibm.com>, linux-s390@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20210915044010.640499-1-linux@roeck-us.net>
From:   Christian Borntraeger <borntraeger@de.ibm.com>
Message-ID: <80b7dbc9-0c09-197f-0f40-ab92d2e3fe3c@de.ibm.com>
Date:   Wed, 15 Sep 2021 11:02:03 +0200
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On 15.09.21 06:40, Guenter Roeck wrote:
> s390:allmodconfig fails to build with the following errors.
> 
> arch/s390/kernel/syscall.c: In function '__do_syscall':
> arch/s390/kernel/syscall.c:168:1: error:
> 	'__do_syscall' uses dynamic stack allocation
> 
> lib/test_kasan.c: In function 'kasan_alloca_oob_right':
> lib/test_kasan.c:782:1: error:
> 	'kasan_alloca_oob_right' uses dynamic stack allocation
> 
> lib/test_kasan.c: In function 'kasan_alloca_oob_left':
> lib/test_kasan.c:767:1: error:
> 	'kasan_alloca_oob_left' uses dynamic stack allocation
> 
> The first error is seen if RANDOMIZE_KSTACK_OFFSET_DEFAULT,
> WARN_DYNAMIC_STACK, and WERROR are enabled. The other problems
> are seen if KASAN_KUNIT_TEST, WARN_DYNAMIC_STACK, and WERROR
> are enabled.
> 
> It does not make sense to abort a build in that situation.
> If either RANDOMIZE_KSTACK_OFFSET_DEFAULT or KASAN_KUNIT_TEST
> is enabled, dynamic stack allocation is on purpose and should
> not fail the build. Add dependencies to reflect that situation.
> 

Thanks for the patch. I think Heiko (on vacation) has a patch to
get rid  of this config alltogether, which is probably the better
solution.


> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
>   arch/s390/Kconfig | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
> index 2bd90c51efd3..776b730e2d15 100644
> --- a/arch/s390/Kconfig
> +++ b/arch/s390/Kconfig
> @@ -688,6 +688,7 @@ config STACK_GUARD
>   config WARN_DYNAMIC_STACK
>   	def_bool n
>   	prompt "Emit compiler warnings for function with dynamic stack usage"
> +	depends on !WERROR || (!RANDOMIZE_KSTACK_OFFSET_DEFAULT && !KASAN_KUNIT_TEST)
>   	help
>   	  This option enables the compiler option -mwarn-dynamicstack. If the
>   	  compiler supports this options generates warnings for functions
>