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From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
To: Kees Cook <keescook@chromium.org>, Miroslav Benes <mbenes@suse.cz>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: Re: sparse warnings in overflow.h
Date: Thu, 7 Jun 2018 21:25:09 +0200	[thread overview]
Message-ID: <4d2aaa98-1655-3ab8-8ce8-bf4b9c7d2dbc@rasmusvillemoes.dk> (raw)
In-Reply-To: <CAGXu5j+XFR7BtYPU6G4CeLFREWevN+GC1FPX1hPAYA1LRBM9Bg@mail.gmail.com>

On 2018-06-07 20:35, Kees Cook wrote:
> On Thu, Jun 7, 2018 at 4:01 AM, Miroslav Benes <mbenes@suse.cz> wrote:
>>
>> Hi Kees,
>>
>> sparse (make C=1) gives me this warnings today...
>>
>> ./include/linux/overflow.h:254:13: error: undefined identifier '__builtin_mul_overflow'
>> ./include/linux/overflow.h:254:13: error: incorrect type in conditional
>> ./include/linux/overflow.h:254:13:    got void
>> ./include/linux/overflow.h:256:13: error: undefined identifier '__builtin_add_overflow'
>> ./include/linux/overflow.h:256:13: error: incorrect type in conditional
>> ./include/linux/overflow.h:256:13:    got void
>>
>> This hunk obviously fixes it, but I'm really not sure if it is a proper
>> fix.
>>
>> diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
>> index f1a7492a5cc8..15e55b89e952 100644
>> --- a/include/linux/compiler-gcc.h
>> +++ b/include/linux/compiler-gcc.h
>> @@ -344,6 +344,6 @@
>>   */
>>  #define uninitialized_var(x) x = x
>>
>> -#if GCC_VERSION >= 50100
>> +#if GCC_VERSION >= 50100 && !defined(__CHECKER__)
>>  #define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
>>  #endif
>>
>> Any idea?
> 
> Hi! Yeah, that's probably the correct approach. If the checker doesn't
> have it, the builtins need to be disabled. :)

IIRC, the problem is that sparse pretends to be the gcc sparse itself
was built with, which is obviously entirely unrelated to the C dialect
that that particular sparse version groks. Sigh. Ack to the fix above.

Rasmus

  reply	other threads:[~2018-06-07 19:25 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-07 11:01 Miroslav Benes
2018-06-07 18:35 ` Kees Cook
2018-06-07 19:25   ` Rasmus Villemoes [this message]
2018-06-07 23:45     ` Luc Van Oostenryck
2018-06-08  6:34   ` [PATCH] compiler-gcc.h: don't set COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW for sparse Miroslav Benes

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