Received-SPF: pass (google.com: domain of linux-kernel+bounces-166386-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
Date: Thu, 2 May 2024 12:21:28 +0100
From: Will Deacon <will@kernel.org>
To: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Boqun Feng <boqun.feng@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	Jakub Kicinski <kuba@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Arnd Bergmann <arnd@arndb.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	"David S. Miller" <davem@davemloft.net>,
	David Ahern <dsahern@kernel.org>,
	Eric Dumazet <edumazet@google.com>, Paolo Abeni <pabeni@redhat.com>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Uros Bizjak <ubizjak@gmail.com>, linux-kernel@vger.kernel.org,
	x86@kernel.org, linux-arch@vger.kernel.org, netdev@vger.kernel.org,
	linux-hardening@vger.kernel.org
Subject: Re: [PATCH 2/4] arm64: atomics: lse: Silence intentional wrapping
 addition
Message-ID: <20240502112127.GA17013@willie-the-truck>
References: <20240424191225.work.780-kees@kernel.org>
 <20240424191740.3088894-2-keescook@chromium.org>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20240424191740.3088894-2-keescook@chromium.org>
User-Agent: Mutt/1.10.1 (2018-07-13)

On Wed, Apr 24, 2024 at 12:17:35PM -0700, Kees Cook wrote:
> Annotate atomic_add_return() and atomic_sub_return() to avoid signed
> overflow instrumentation. They are expected to wrap around.
> 
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> Cc: Will Deacon <will@kernel.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Boqun Feng <boqun.feng@gmail.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: linux-arm-kernel@lists.infradead.org
> ---
>  arch/arm64/include/asm/atomic_lse.h | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)

How come the ll/sc routines (in atomic_ll_sc.h) don't need the same
treatment? If that's just an oversight, then maybe it's better to
instrument the higher-level wrappers in asm/atomic.h?

Will