From: Joel Fernandes <joel@joelfernandes.org>
To: rcu <rcu@vger.kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Rushikesh S Kadam <rushikesh.s.kadam@intel.com>,
"Uladzislau Rezki (Sony)" <urezki@gmail.com>,
Neeraj upadhyay <neeraj.iitr10@gmail.com>,
Frederic Weisbecker <frederic@kernel.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
vineeth@bitbyteword.org, Marco Elver <elver@google.com>
Subject: Re: [PATCH v2 1/1] context_tracking: Use arch_atomic_read() in __ct_state for KASAN
Date: Wed, 22 Jun 2022 18:58:26 -0400 [thread overview]
Message-ID: <CAEXW_YQaXGmwmFbfSPAEG9SpfuSy3muhWhTFeuxSY4OwUWeHdA@mail.gmail.com> (raw)
In-Reply-To: <20220622225102.2112026-2-joel@joelfernandes.org>
Apologies, I accidentally picked this specific commit up in my recent
git format-patch which ended up sending it out. Totally unintended.
On Wed, Jun 22, 2022 at 6:51 PM Joel Fernandes (Google)
<joel@joelfernandes.org> wrote:
>
> From: "Paul E. McKenney" <paulmck@kernel.org>
>
> Context tracking's __ct_state() function can be invoked from noinstr state
> where RCU is not watching. This means that its use of atomic_read()
> causes KASAN to invoke the non-noinstr __kasan_check_read() function
> from the noinstr function __ct_state(). This is problematic because
> someone tracing the __kasan_check_read() function could get a nasty
> surprise because of RCU not watching.
>
> This commit therefore replaces the __ct_state() function's use of
> atomic_read() with arch_atomic_read(), which KASAN does not attempt to
> add instrumention to.
>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> Cc: Frederic Weisbecker <frederic@kernel.org>
> Cc: Marco Elver <elver@google.com>
> Reviewed-by: Marco Elver <elver@google.com>
> ---
> include/linux/context_tracking_state.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h
> index 0aecc07fb4f5..81c51e5f0314 100644
> --- a/include/linux/context_tracking_state.h
> +++ b/include/linux/context_tracking_state.h
> @@ -49,7 +49,7 @@ DECLARE_PER_CPU(struct context_tracking, context_tracking);
>
> static __always_inline int __ct_state(void)
> {
> - return atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_STATE_MASK;
> + return arch_atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_STATE_MASK;
> }
> #endif
>
> --
> 2.37.0.rc0.104.g0611611a94-goog
>
next prev parent reply other threads:[~2022-06-22 22:58 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-22 22:50 [PATCH v2 0/8] Implement call_rcu_lazy() and miscellaneous fixes Joel Fernandes (Google)
2022-06-22 22:50 ` [PATCH v2 1/1] context_tracking: Use arch_atomic_read() in __ct_state for KASAN Joel Fernandes (Google)
2022-06-22 22:58 ` Joel Fernandes [this message]
2022-06-22 22:50 ` [PATCH v2 1/8] rcu: Introduce call_rcu_lazy() API implementation Joel Fernandes (Google)
2022-06-22 23:18 ` Joel Fernandes
2022-06-26 4:00 ` Paul E. McKenney
2022-06-23 1:38 ` kernel test robot
2022-06-26 4:00 ` Paul E. McKenney
2022-07-08 18:43 ` Joel Fernandes
2022-07-08 23:10 ` Paul E. McKenney
2022-07-10 2:26 ` Joel Fernandes
2022-07-10 16:03 ` Paul E. McKenney
2022-07-12 20:53 ` Joel Fernandes
2022-07-12 21:04 ` Paul E. McKenney
2022-07-12 21:10 ` Joel Fernandes
2022-07-12 22:41 ` Paul E. McKenney
2022-06-29 11:53 ` Frederic Weisbecker
2022-06-29 17:05 ` Paul E. McKenney
2022-06-29 20:29 ` Joel Fernandes
2022-06-29 22:01 ` Frederic Weisbecker
2022-06-30 14:08 ` Joel Fernandes
2022-06-22 22:50 ` [PATCH v2 2/8] rcu: shrinker for lazy rcu Joel Fernandes (Google)
2022-06-22 22:50 ` [PATCH v2 3/8] fs: Move call_rcu() to call_rcu_lazy() in some paths Joel Fernandes (Google)
2022-06-22 22:50 ` [PATCH v2 4/8] rcu/nocb: Add option to force all call_rcu() to lazy Joel Fernandes (Google)
2022-06-22 22:50 ` [PATCH v2 5/8] rcu/nocb: Wake up gp thread when flushing Joel Fernandes (Google)
2022-06-26 4:06 ` Paul E. McKenney
2022-06-26 13:45 ` Joel Fernandes
2022-06-26 13:52 ` Paul E. McKenney
2022-06-26 14:37 ` Joel Fernandes
2022-06-22 22:51 ` [PATCH v2 6/8] rcuscale: Add test for using call_rcu_lazy() to emulate kfree_rcu() Joel Fernandes (Google)
2022-06-23 2:09 ` kernel test robot
2022-06-23 3:00 ` kernel test robot
2022-06-23 8:10 ` kernel test robot
2022-06-26 4:13 ` Paul E. McKenney
2022-07-08 4:25 ` Joel Fernandes
2022-07-08 23:06 ` Paul E. McKenney
2022-07-12 20:27 ` Joel Fernandes
2022-07-12 20:58 ` Paul E. McKenney
2022-07-12 21:15 ` Joel Fernandes
2022-07-12 22:41 ` Paul E. McKenney
2022-06-22 22:51 ` [PATCH v2 7/8] rcu/nocb: Rewrite deferred wake up logic to be more clean Joel Fernandes (Google)
2022-06-22 22:51 ` [PATCH v2 8/8] rcu/kfree: Fix kfree_rcu_shrink_count() return value Joel Fernandes (Google)
2022-06-26 4:17 ` Paul E. McKenney
2022-06-27 18:56 ` Uladzislau Rezki
2022-06-27 20:59 ` Paul E. McKenney
2022-06-27 21:18 ` Joel Fernandes
2022-06-27 21:43 ` Paul E. McKenney
2022-06-28 16:56 ` Joel Fernandes
2022-06-28 21:13 ` Joel Fernandes
2022-06-29 16:56 ` Paul E. McKenney
2022-06-29 19:47 ` Joel Fernandes
2022-06-29 21:07 ` Paul E. McKenney
2022-06-30 14:25 ` Joel Fernandes
2022-06-30 15:29 ` Paul E. McKenney
2022-06-29 16:52 ` Paul E. McKenney
2022-06-26 3:12 ` [PATCH v2 0/8] Implement call_rcu_lazy() and miscellaneous fixes Paul E. McKenney
2022-07-08 4:17 ` Joel Fernandes
2022-07-08 22:45 ` Paul E. McKenney
2022-07-10 1:38 ` Joel Fernandes
2022-07-10 15:47 ` Paul E. McKenney
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