Re: [PATCH] locking/atomics: don't alias ____ptr

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Ingo Molnar <mingo@kernel.org>
Cc: Dmitry Vyukov <dvyukov@google.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Will Deacon <will.deacon@arm.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	kasan-dev <kasan-dev@googlegroups.com>,
	"x86@kernel.org" <x86@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] locking/atomics: don't alias ____ptr
Date: Wed, 28 Jun 2017 14:12:52 +0200	[thread overview]
Message-ID: <20170628121246.qnk2csgzbgpqrmw3@linutronix.de> (raw)
In-Reply-To: <1c1cbbfb-8e34-dd33-0e73-bbb2a758e962@virtuozzo.com>

On 2017-06-28 14:15:18 [+0300], Andrey Ryabinin wrote:
> The main problem here is that arch_cmpxchg64_local() calls cmpxhg_local() instead of using arch_cmpxchg_local().
> 
> So, the patch bellow should fix the problem, also this will fix double instrumentation of cmpcxchg64[_local]().
> But I haven't tested this patch yet.

tested, works. Next step?

> ---
>  arch/x86/include/asm/cmpxchg_64.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/include/asm/cmpxchg_64.h b/arch/x86/include/asm/cmpxchg_64.h
> index fafaebacca2d..7046a3cc2493 100644
> --- a/arch/x86/include/asm/cmpxchg_64.h
> +++ b/arch/x86/include/asm/cmpxchg_64.h
> @@ -9,13 +9,13 @@ static inline void set_64bit(volatile u64 *ptr, u64 val)
>  #define arch_cmpxchg64(ptr, o, n)					\
>  ({									\
>  	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\
> -	cmpxchg((ptr), (o), (n));					\
> +	arch_cmpxchg((ptr), (o), (n));					\
>  })
>  
>  #define arch_cmpxchg64_local(ptr, o, n)					\
>  ({									\
>  	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\
> -	cmpxchg_local((ptr), (o), (n));					\
> +	arch_cmpxchg_local((ptr), (o), (n));					\
>  })
>  
>  #define system_has_cmpxchg_double() boot_cpu_has(X86_FEATURE_CX16)

Sebastian