linux-kernel - Re: [PATCH] ubsan: don't mark __ubsan_handle_builtin

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Message-ID: <cca8985f-8279-7bd8-3ebe-f2f79cd98b91@virtuozzo.com>
Date:   Wed, 7 Nov 2018 17:44:27 +0300
From:   Andrey Ryabinin <aryabinin@...tuozzo.com>
To:     Olof Johansson <olof@...om.net>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Nicolas Pitre <nico@...aro.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ubsan: don't mark __ubsan_handle_builtin_unreachable as
 noreturn



On 11/03/2018 12:27 AM, Olof Johansson wrote:
> On Mon, Feb 5, 2018 at 2:31 AM Andrey Ryabinin <aryabinin@...tuozzo.com> wrote:
>>
>> On 02/05/2018 01:15 PM, Arnd Bergmann wrote:
>>> On Mon, Feb 5, 2018 at 10:02 AM, Andrey Ryabinin
>>> <aryabinin@...tuozzo.com> wrote:
>>>>
>>>>
>>>> On 02/02/2018 06:47 PM, Arnd Bergmann wrote:
>>>>> gcc-8 complains about the prototype for this function:
>>>>>
>>>>> lib/ubsan.c:432:1: error: ignoring attribute 'noreturn' in declaration of a built-in function '__ubsan_handle_builtin_unreachable' because it conflicts with attribute 'const' [-Werror=attributes]
>>>>>
>>>>
>>>> That's actually a bug in GCC. In GCC __ubsan_handle_builtin_unreachable declared
>>>> with 'noreturn' and 'const' attributes:
>>>>
>>>> DEF_SANITIZER_BUILTIN(BUILT_IN_UBSAN_HANDLE_BUILTIN_UNREACHABLE,
>>>>                       "__ubsan_handle_builtin_unreachable",
>>>>                       BT_FN_VOID_PTR,
>>>>                       ATTR_COLD_CONST_NORETURN_NOTHROW_LEAF_LIST)
>>>>
>>>>
>>>> But const attribute doesn't make any sense for function that returns void or doesn't return at all.
>>>> Given that gcc-8 has not released yet, it would be better to fix this bug there.
>>>
>>> Ok. Should I open a gcc bug, or will you take care of it?
>>>
>>
>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84210
> 
> 8.2.0 still shows this, and there's been no movement on that bug. How
> about we pick up this patch until it's been resolved?
> 

Sure, I'll add info about GCC bug in changelog and resend the patch.

> 
> -Olof
>